In this work we present an advanced computational pipeline for the approximation and prediction of the lift coefficient of a parametrized airfoil profile. The non-intrusive reduced order method is based on dynamic mode decomposition (DMD) and it is coupled with dynamic active subspaces (DyAS) to enhance the future state prediction of the target function and reduce the parameter space dimensionality. The pipeline is based on high-fidelity simulations carried out by the application of finite volume method for turbulent flows, and automatic mesh morphing through radial basis functions interpolation technique. The proposed pipeline is able to save 1/3 of the overall computational resources thanks to the application of DMD. Moreover exploiting DyAS and performing the regression on a lower dimensional space results in the reduction of the relative error in the approximation of the time-varying lift coefficient by a factor 2 with respect to using only the DMD.

}, url = {https://arxiv.org/abs/2001.05237}, author = {Marco Tezzele and Nicola Demo and Giovanni Stabile and Andrea Mola and Gianluigi Rozza} } @article {mine-02-02-011, title = {MicroMotility: State of the art, recent accomplishments and perspectives on the mathematical modeling of bio-motility at microscopic scales}, journal = {Mathematics in Engineering}, volume = {2}, number = {mine-02-02-01}, year = {2020}, pages = {230}, type = {Perspective}, abstract = {Mathematical modeling and quantitative study of biological motility (in particular, of motility at microscopic scales) is producing new biophysical insight and is offering opportunities for new discoveries at the level of both fundamental science and technology. These range from the explanation of how complex behavior at the level of a single organism emerges from body architecture, to the understanding of collective phenomena in groups of organisms and tissues, and of how these forms of swarm intelligence can be controlled and harnessed in engineering applications, to the elucidation of processes of fundamental biological relevance at the cellular and sub-cellular level. In this paper, some of the most exciting new developments in the fields of locomotion of unicellular organisms, of soft adhesive locomotion across scales, of the study of pore translocation properties of knotted DNA, of the development of synthetic active solid sheets, of the mechanics of the unjamming transition in dense cell collectives, of the mechanics of cell sheet folding in volvocalean algae, and of the self-propulsion of topological defects in active matter are discussed. For each of these topics, we provide a brief state of the art, an example of recent achievements, and some directions for future research.

}, keywords = {active matter, adhesive locomotion, cell motility, cell sheet folding, knotted DNA, topological defects, unicellular swimmers, unjamming transition}, issn = {2640-3501}, doi = {10.3934/mine.2020011}, url = {http://dx.doi.org/10.3934/mine.2020011}, author = {Daniele Agostinelli and Roberto Cerbino and Del Alamo, Juan C and Antonio DeSimone and Stephanie H{\"o}hn and Cristian Micheletti and Giovanni Noselli and Eran Sharon and Julia Yeomans} } @article {Dal-MasoHeltai-2020-a, title = {A numerical study of the jerky crack growth in elastoplastic materials with localized plasticity}, journal = {Journal of Convex Analysis}, year = {2020}, note = {To appear}, url = {https://arxiv.org/abs/2004.12705}, author = {Gianni Dal Maso and Luca Heltai} } @article {Agostinelli2020.07.06.188987, title = {Nutations in plant shoots: endogenous and exogenous factors in the presence of mechanical deformations}, year = {2020}, institution = {Cold Spring Harbor Laboratory}, type = {preprint}, abstract = {We present a three-dimensional morphoelastic rod model capable to describe the morphogenesis of growing plant shoots, as driven by differential growth at the tip. We discuss the evolution laws for endogenous oscillators, straightening mechanisms and reorientations to directional cues, such as phototropic responses to a far light source and gravitropic reactions governed by the statoliths avalanche dynamics. We use this model to investigate the role of elastic deflections due to gravity loading in circumnutating plant shoots. We show that, in the absence of endogenous cues, pendular and circular oscillations arise as a critical length is attained, thus suggesting the occurrence of a Hopf bifurcation reminiscent of flutter instabilities exhibited by structural systems under nonconservative loads. When also oscillations due to endogenous cues are present, their weight relative to those associated with the Hopf instability varies in time as the shoot length and other biomechanical properties change. Thanks to the simultaneous occurrence of these two oscillatory mechanisms, we are able to reproduce a variety of complex behaviors, including trochoid-like patterns, which evolve into circular orbits as the shoot length increases, and the amplitude of the flutter induced oscillations becomes dominant. Our findings suggest that the relative importance of the two mechanisms is an emergent property of the system that is affected by the amplitude of elastic deformations, and highlight the crucial role of elasticity in the analysis of circumnutations.Competing Interest StatementThe authors have declared no competing interest.

}, doi = {10.1101/2020.07.06.188987}, url = {https://www.biorxiv.org/content/early/2020/07/06/2020.07.06.188987}, author = {Daniele Agostinelli and Antonio DeSimone and Giovanni Noselli} } @unpublished {2020, title = {A POD-Galerkin reduced order model of a turbulent convective buoyant flow of sodium over a backward-facing step}, year = {2020}, abstract = {A Finite-Volume based POD-Galerkin reduced order modeling strategy for steady-state Reynolds averaged Navier{\textendash}Stokes (RANS) simulation is extended for low-Prandtl number flow. The reduced order model is based on a full order model for which the effects of buoyancy on the flow and heat transfer are characterized by varying the Richardson number. The Reynolds stresses are computed with a linear eddy viscosity model. A single gradient diffusion hypothesis, together with a local correlation for the evaluation of the turbulent Prandtl number, is used to model the turbulent heat fluxes. The contribution of the eddy viscosity and turbulent thermal diffusivity fields are considered in the reduced order model with an interpolation based data-driven method. The reduced order model is tested for buoyancy-aided turbulent liquid sodium flow over a vertical backward-facing step with a uniform heat flux applied on the wall downstream of the step. The wall heat flux is incorporated with a Neumann boundary condition in both the full order model and the reduced order model. The velocity and temperature profiles predicted with the reduced order model for the same and new Richardson numbers inside the range of parameter values are in good agreement with the RANS simulations. Also, the local Stanton number and skin friction distribution at the heated wall are qualitatively well captured. Finally, the reduced order simulations, performed on a single core, are about $10^5$ times faster than the RANS simulations that are performed on eight cores.

}, url = {https://arxiv.org/abs/2003.01114}, author = {Kelbij Star and Giovanni Stabile and Gianluigi Rozza and Joris Degroote} } @unpublished {2020, title = {A supervised learning approach involving active subspaces for an efficient genetic algorithm in high-dimensional optimization problems}, year = {2020}, abstract = {In this work, we present an extension of the genetic algorithm (GA) which exploits the active subspaces (AS) property to evolve the individuals on a lower dimensional space. In many cases, GA requires in fact more function evaluations than others optimization method to converge to the optimum. Thus, complex and high-dimensional functions may result intractable with the standard algorithm. To address this issue, we propose to linearly map the input parameter space of the original function onto its AS before the evolution, performing the mutation and mate processes in a lower dimensional space. In this contribution, we describe the novel method called ASGA, presenting differences and similarities with the standard GA method. We test the proposed method over n-dimensional benchmark functions {\textendash} Rosenbrock, Ackley, Bohachevsky, Rastrigin, Schaffer N. 7, and Zakharov {\textendash} and finally we apply it to an aeronautical shape optimization problem.

}, url = {https://arxiv.org/abs/2006.07282}, author = {Nicola Demo and Marco Tezzele and Gianluigi Rozza} } @conference {2019, title = {A complete data-driven framework for the efficient solution of parametric shape design and optimisation in naval engineering problems}, booktitle = {VIII International Conference on Computational Methods in Marine Engineering}, year = {2019}, abstract = {In the reduced order modeling (ROM) framework, the solution of a parametric partial differential equation is approximated by combining the high-fidelity solutions of the problem at hand for several properly chosen configurations. Examples of the ROM application, in the naval field, can be found in [31, 24]. Mandatory ingredient for the ROM methods is the relation between the high-fidelity solutions and the parameters. Dealing with geometrical parameters, especially in the industrial context, this relation may be unknown and not trivial (simulations over hand morphed geometries) or very complex (high number of parameters or many nested morphing techniques). To overcome these scenarios, we propose in this contribution an efficient and complete data-driven framework involving ROM techniques for shape design and optimization, extending the pipeline presented in [7]. By applying the singular value decomposition (SVD) to the points coordinates defining the hull geometry {\textendash}- assuming the topology is inaltered by the deformation {\textendash}-, we are able to compute the optimal space which the deformed geometries belong to, hence using the modal coefficients as the new parameters we can reconstruct the parametric formulation of the domain. Finally the output of interest is approximated using the proper orthogonal decomposition with interpolation technique. To conclude, we apply this framework to a naval shape design problem where the bulbous bow is morphed to reduce the total resistance of the ship advancing in calm water.

}, url = {https://arxiv.org/abs/1905.05982}, author = {Demo, Nicola and Tezzele, Marco and Mola, Andrea and Rozza, Gianluigi} } @article {ArndtBangerthClevenger-2019-a, title = {The deal.II Library, Version 9.1}, journal = {Journal of Numerical Mathematics}, year = {2019}, abstract = {This paper provides an overview of the new features of the finite element library deal.II, version 9.1.}, issn = {15702820}, doi = {10.1515/jnma-2019-0064}, author = {Arndt, Daniel and Bangerth, Wolfgang and Clevenger, Thomas C. and Davydov, Denis and Fehling, Marc and Garcia-Sanchez, Daniel and Harper, Graham and Heister, Timo and Heltai, Luca and Kronbichler, Martin and Maguire Kynch, Ross and Maier, Matthias and Pelteret, Jean Paul and Turcksin, Bruno and Wells, David} } @article {cotti2019, title = {Isomonodromy deformations at an irregular singularity with coalescing eigenvalues}, journal = {Duke Math. J.}, volume = {168}, number = {6}, year = {2019}, month = {04}, pages = {967{\textendash}1108}, publisher = {Duke University Press}, abstract = {We consider an n{\texttimes}n linear system of ODEs with an irregular singularity of Poincar\'e rank 1 at z=$\infty$, holomorphically depending on parameter t within a polydisc in Cn centred at t=0. The eigenvalues of the leading matrix at z=$\infty$ coalesce along a locus Δ contained in the polydisc, passing through t=0. Namely, z=$\infty$ is a resonant irregular singularity for t∈Δ. We analyse the case when the leading matrix remains diagonalisable at Δ. We discuss the existence of fundamental matrix solutions, their asymptotics, Stokes phenomenon and monodromy data as t varies in the polydisc, and their limits for t tending to points of Δ. When the deformation is isomonodromic away from Δ, it is well known that a fundamental matrix solution has singularities at Δ. When the system also has a Fuchsian singularity at z=0, we show under minimal vanishing conditions on the residue matrix at z=0 that isomonodromic deformations can be extended to the whole polydisc, including Δ, in such a way that the fundamental matrix solutions and the constant monodromy data are well defined in the whole polydisc. These data can be computed just by considering the system at fixed t=0. Conversely, if the t-dependent system is isomonodromic in a small domain contained in the polydisc not intersecting Δ, if the entries of the Stokes matrices with indices corresponding to coalescing eigenvalues vanish, then we show that Δ is not a branching locus for the fundamental matrix solutions. The importance of these results for the analytic theory of Frobenius Manifolds is explained. An application to Painlev\'e equations is discussed.

}, doi = {10.1215/00127094-2018-0059}, url = {https://doi.org/10.1215/00127094-2018-0059}, author = {Giordano Cotti and Boris Dubrovin and Davide Guzzetti} } @article {AGOSTINELLI2019103702, title = {Nutations in growing plant shoots: The role of elastic deformations due to gravity loading}, journal = {Journal of the Mechanics and Physics of Solids}, year = {2019}, pages = {103702}, abstract = {The effect of elastic deformations induced by gravity loading on the active circumnutation movements of growing plant shoots is investigated. We consider first a discrete model (a gravitropic spring-pendulum system) and then a continuous rod model which is analyzed both analytically (under the assumption of small deformations) and numerically (in the large deformation regime). We find that, for a choice of material parameters consistent with values reported in the available literature on plant shoots, rods of sufficient length may exhibit lateral oscillations of increasing amplitude, which eventually converge to limit cycles. This behavior strongly suggests the occurrence of a Hopf bifurcation, just as for the gravitropic spring-pendulum system, for which this result is rigorously established. At least in this restricted set of material parameters, our analysis supports a view of Darwin{\textquoteright}s circumnutations as a biological analogue to structural systems exhibiting flutter instabilities, i.e., spontaneous oscillations away from equilibrium configurations driven by non-conservative loads. Here, in the context of nutation movements of growing plant shoots, the energy needed to sustain oscillations is continuously supplied to the system by the internal biochemical machinery presiding the capability of plants to maintain a vertical pose.

}, keywords = {Circumnutations, Flutter instability, Gravitropism, Hopf bifurcation}, issn = {0022-5096}, doi = {10.1016/j.jmps.2019.103702}, url = {https://doi.org/10.1016/j.jmps.2019.103702}, author = {Daniele Agostinelli and Alessandro Lucantonio and Giovanni Noselli and Antonio DeSimone} } @article {1903.04302, title = {Quasi-continuous vector fields on RCD spaces}, year = {2019}, author = {Cl{\'e}ment Debin and Nicola Gigli and Enrico Pasqualetto} } @conference {2019, title = {Shape optimization through proper orthogonal decomposition with interpolation and dynamic mode decomposition enhanced by active subspaces}, booktitle = {VIII International Conference on Computational Methods in Marine Engineering}, year = {2019}, abstract = {We propose a numerical pipeline for shape optimization in naval engineering involving two different non-intrusive reduced order method (ROM) techniques. Such methods are proper orthogonal decomposition with interpolation (PODI) and dynamic mode decomposition (DMD). The ROM proposed will be enhanced by active subspaces (AS) as a pre-processing tool that reduce the parameter space dimension and suggest better sampling of the input space. We will focus on geometrical parameters describing the perturbation of a reference bulbous bow through the free form deformation (FFD) technique. The ROM are based on a finite volume method (FV) to simulate the multi-phase incompressible flow around the deformed hulls. In previous works we studied the reduction of the parameter space in naval engineering through AS [38, 10] focusing on different parts of the hull. PODI and DMD have been employed for the study of fast and reliable shape optimization cycles on a bulbous bow in [9]. The novelty of this work is the simultaneous reduction of both the input parameter space and the output fields of interest. In particular AS will be trained computing the total drag resistance of a hull advancing in calm water and its gradients with respect to the input parameters. DMD will improve the performance of each simulation of the campaign using only few snapshots of the solution fields in order to predict the regime state of the system. Finally PODI will interpolate the coefficients of the POD decomposition of the output fields for a fast approximation of all the fields at new untried parameters given by the optimization algorithm. This will result in a non-intrusive data-driven numerical optimization pipeline completely independent with respect to the full order solver used and it can be easily incorporated into existing numerical pipelines, from the reference CAD to the optimal shape.

}, url = {https://arxiv.org/abs/1905.05483}, author = {Tezzele, Marco and Demo, Nicola and Rozza, Gianluigi} } @article {de2019sharp, title = {The sharp quantitative isocapacitary inequality}, year = {2019}, author = {Guido De Philippis and Michele Marini and Ekaterina Mukoseeva} } @article {2018, title = {On the Cauchy problem for the wave equation on time-dependent domains}, number = {SISSA;19/2018/MATE}, year = {2018}, institution = {SISSA}, abstract = {We introduce a notion of solution to the wave equation on a suitable class of time-dependent domains and compare it with a previous de nition. We prove an existence result for the solution of the Cauchy problem and present some additional conditions which imply uniqueness.}, url = {http://preprints.sissa.it/handle/1963/35314}, author = {Gianni Dal Maso and Rodica Toader} } @article {20.500.11767_81694, title = {The deal.II Library, Version 9.0}, journal = {JOURNAL OF NUMERICAL MATHEMATICS}, year = {2018}, doi = {10.1515/jnma-2018-0054}, url = {https://doi.org/10.1515/jnma-2018-0054}, author = {Giovanni Alzetta and Arndt, Daniel and W. Bangerth and Boddu, Vishal and Brands, Benjamin and Denis Davydov and Gassm{\"o}ller, Rene and Timo Heister and Luca Heltai and Kormann, Katharina and Martin Kronbichler and Matthias Maier and Pelteret, Jean-Paul and B. Turcksin and David Wells} } @proceedings {demo2018efficient, title = {An efficient shape parametrisation by free-form deformation enhanced by active subspace for hull hydrodynamic ship design problems in open source environment}, year = {2018}, publisher = {International Society of Offshore and Polar Engineers}, address = {Sapporo, Japan}, abstract = {In this contribution, we present the results of the application of a parameter space reduction methodology based on active subspaces to the hull hydrodynamic design problem. Several parametric deformations of an initial hull shape are considered to assess the influence of the shape parameters considered on the hull total drag. The hull resistance is typically computed by means of numerical simulations of the hydrodynamic flow past the ship. Given the high number of parameters involved - which might result in a high number of time consuming hydrodynamic simulations - assessing whether the parameters space can be reduced would lead to considerable computational cost reduction. Thus, the main idea of this work is to employ the active subspaces to identify possible lower dimensional structures in the parameter space, or to verify the parameter distribution in the position of the control points. To this end, a fully automated procedure has been implemented to produce several small shape perturbations of an original hull CAD geometry which are then used to carry out high-fidelity flow simulations and collect data for the active subspaces analysis. To achieve full automation of the open source pipeline described, both the free form deformation methodology employed for the hull perturbations and the solver based on unsteady potential flow theory, with fully nonlinear free surface treatment, are directly interfaced with CAD data structures and operate using IGES vendor-neutral file formats as input files. The computational cost of the fluid dynamic simulations is further reduced through the application of dynamic mode decomposition to reconstruct the steady state total drag value given only few initial snapshots of the simulation. The active subspaces analysis is here applied to the geometry of the DTMB-5415 naval combatant hull, which is which is a common benchmark in ship hydrodynamics simulations.}, keywords = {Active subspaces, Boundary element method, Dynamic mode decomposition, Fluid structure interaction, Free form deformation, Fully nonlinear potential, Numerical towing tank}, issn = {978-1-880653-87-6}, url = {https://www.onepetro.org/conference-paper/ISOPE-I-18-481}, author = {Nicola Demo and Marco Tezzele and Andrea Mola and Gianluigi Rozza} } @article {2018, title = {Existence for elastodynamic Griffith fracture with a weak maximal dissipation condition}, number = {SISSA;04/2018/MATE}, year = {2018}, abstract = {We consider a model of elastodynamics with fracture evolution, based on energy-dissipation balance and a maximal dissipation condition. We prove an existence result in the case of planar elasticity with a free crack path, where the maximal dissipation condition is satisfied among suitably regular competitor cracks.}, url = {http://preprints.sissa.it/handle/1963/35308}, author = {Gianni Dal Maso and Cristopher J. Larsen and Rodica Toader} } @article {demo2018ezyrb, title = {EZyRB: Easy Reduced Basis method}, journal = {The Journal of Open Source Software}, volume = {3}, number = {24}, year = {2018}, pages = {661}, doi = {10.21105/joss.00661}, url = {https://joss.theoj.org/papers/10.21105/joss.00661}, author = {Nicola Demo and Marco Tezzele and Gianluigi Rozza} } @article {agostiniani2018foldable, title = {Foldable structures made of hydrogel bilayers}, year = {2018}, author = {Virginia Agostiniani and Antonio DeSimone and Alessandro Lucantonio and Danka Lu{\v c}i{\'c}} } @article {2018, title = {Local moduli of semisimple Frobenius coalescent structures}, number = {arXiv;1712.08575}, year = {2018}, institution = {SISSA}, abstract = {There is a conjectural relation, formulated by the second author, between the enumerative geometry of a wide class of smooth projective varieties and their derived category of coherent sheaves. In particular, there is an increasing interest for an explicit description of certain local invariants, called monodromy data, of semisimple quantum cohomologies in terms of characteristic classes of exceptional collections in the derived categories. Being intentioned to address this problem, which, to our opinion, is still not well understood, we have realized that some issues in the theory of Frobenius manifolds need to be preliminarily clarified, and that an extension of the theory itself is necessary, in view of the fact that quantum cohomologies of certain classes of homogeneous spaces may show a coalescence phenomenon.

}, url = {http://preprints.sissa.it/handle/1963/35304}, author = {Giordano Cotti and Boris Dubrovin and Davide Guzzetti} } @article {Dell{\textquoteright}Antonio2018, title = {Lp-Boundedness of Wave Operators for the Three-Dimensional Multi-Centre Point Interaction}, journal = {Annales Henri Poincar{\'e}}, volume = {19}, number = {1}, year = {2018}, month = {Jan}, pages = {283{\textendash}322}, abstract = {We prove that, for arbitrary centres and strengths, the wave operators for three-dimensional Schr{\"o}dinger operators with multi-centre local point interactions are bounded in Lp(R3)for 1\<p\<3 and unbounded otherwise.

}, issn = {1424-0661}, doi = {10.1007/s00023-017-0628-4}, url = {https://doi.org/10.1007/s00023-017-0628-4}, author = {Gianfausto Dell{\textquoteright}Antonio and Alessandro Michelangeli and Raffaele Scandone and Kenji Yajima} } @article {2018, title = {A minimization approach to the wave equation on time-dependent domains}, number = {SISSA;21/2018/MATE}, year = {2018}, institution = {SISSA}, abstract = {We prove the existence of weak solutions to the homogeneous wave equation on a suitable class of time-dependent domains. Using the approach suggested by De Giorgi and developed by Serra and Tilli, such solutions are approximated by minimizers of suitable functionals in space-time.}, url = {http://preprints.sissa.it/handle/1963/35318}, author = {Gianni Dal Maso and Lucia De Luca} } @conference {tezzele2018model, title = {Model Order Reduction by means of Active Subspaces and Dynamic Mode Decomposition for Parametric Hull Shape Design Hydrodynamics}, booktitle = {Technology and Science for the Ships of the Future: Proceedings of NAV 2018: 19th International Conference on Ship \& Maritime Research}, year = {2018}, publisher = {IOS Press}, organization = {IOS Press}, address = {Trieste, Italy}, abstract = {We present the results of the application of a parameter space reduction methodology based on active subspaces (AS) to the hull hydrodynamic design problem. Several parametric deformations of an initial hull shape are considered to assess the influence of the shape parameters on the hull wave resistance. Such problem is relevant at the preliminary stages of the ship design, when several flow simulations are carried out by the engineers to establish a certain sensibility with respect to the parameters, which might result in a high number of time consuming hydrodynamic simulations. The main idea of this work is to employ the AS to identify possible lower dimensional structures in the parameter space. The complete pipeline involves the use of free form deformation to parametrize and deform the hull shape, the full order solver based on unsteady potential flow theory with fully nonlinear free surface treatment directly interfaced with CAD, the use of dynamic mode decomposition to reconstruct the final steady state given only few snapshots of the simulation, and the reduction of the parameter space by AS, and shared subspace. Response surface method is used to minimize the total drag.}, doi = {10.3233/978-1-61499-870-9-569}, url = {http://ebooks.iospress.nl/publication/49270}, author = {Marco Tezzele and Nicola Demo and Mahmoud Gadalla and Andrea Mola and Gianluigi Rozza} } @article {2018, title = {Peristaltic Waves as Optimal Gaits in Metameric Bio-Inspired Robots}, journal = {Frontiers in Robotics and AI}, volume = {5}, year = {2018}, month = {09/2018}, abstract = {*Peristalsis*, i.e., a motion pattern arising from the propagation of muscle contraction and expansion waves along the body, is a common locomotion strategy for limbless animals. Mimicking peristalsis in bio-inspired robots has attracted considerable attention in the literature. It has recently been observed that maximal velocity in a metameric earthworm-like robot is achieved by actuating the segments using a {\textquotedblleft}phase coordination{\textquotedblright} principle. This paper shows that, in fact, peristalsis (which requires not only phase coordination, but also that all segments oscillate at same frequency and amplitude) emerges from optimization principles. More precisely, basing our analysis on the assumption of small deformations, we show that peristaltic waves provide the optimal actuation solution in the ideal case of a periodic infinite system, and that this is approximately true, modulo edge effects, for the real, finite length system. Therefore, this paper confirms the effectiveness of mimicking peristalsis in bio-inspired robots, at least in the small-deformation regime. Further research will be required to test the effectiveness of this strategy if large deformations are allowed.

In this work we apply reduced basis methods for parametric PDEs to an isogeometric formulation based on

NURBS. The motivation for this work is an integrated and complete work pipeline from CAD to parametrization

of domain geometry, then from full order to certified reduced basis solution. IsoGeometric Analysis

\ (IGA) is a growing research theme in scientic computing and computational mechanics, as well as reduced

basis methods for parametric PDEs. Their combination enhances the solution of some class of problems,

especially the ones characterized by parametrized geometries we introduced in this work. For a general

overview on Reduced Basis (RB) methods we recall [7, 15] and on IGA [3]. This work wants to demonstrate

that it is also possible for some class of problems to deal with ane geometrical parametrization combined

with a NURBS IGA formulation. This is what this work brings as original ingredients with respect to other

works dealing with reduced order methods and IGA (set in a non-affine formulation, and using a POD [2]\

sampling without certication: see for example for potential\ flows [12] and for Stokes\ flows [17]). In this work

we show a certication of accuracy and a complete integration between IGA formulation and parametric

certified greedy RB formulation. Section 2 recalls the abstract setting for parametrized PDEs, Section 3

recalls IGA setting, Section 4 deals with RB formulation, and Section 5 illustrates two numerical examples in heat transfer with different parametrization.

}, isbn = {978-3-319-65869-8}, author = {Denis Devaud and Gianluigi Rozza} } @article {Dassi2017, title = {Curvature-adapted remeshing of {CAD} surfaces}, journal = {Engineering with Computers}, volume = {34}, number = {3}, year = {2017}, month = {dec}, pages = {565{\textendash}576}, publisher = {Springer Nature}, doi = {10.1007/s00366-017-0558-2}, url = {https://doi.org/10.1007/s00366-017-0558-2}, author = {Franco Dassi and Andrea Mola and Hang Si} } @article {20.500.11767_47950, title = {The deal.II Library, Version 8.5}, journal = {JOURNAL OF NUMERICAL MATHEMATICS}, volume = {25}, year = {2017}, pages = {137{\textendash}145}, doi = {10.1515/jnma-2017-0058}, url = {https://www.dealii.org/deal85-preprint.pdf}, author = {Arndt, Daniel and W. Bangerth and Denis Davydov and Timo Heister and Luca Heltai and Martin Kronbichler and Matthias Maier and Pelteret, Jean-Paul and B. Turcksin and David Wells} } @inbook {Iandoli2017, title = {Dispersive Estimates for Schr{\"o}dinger Operators with Point Interactions in ℝ3}, booktitle = {Advances in Quantum Mechanics: Contemporary Trends and Open Problems}, year = {2017}, pages = {187{\textendash}199}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {The study of dispersive properties of Schr{\"o}dinger operators with point interactions is a fundamental tool for understanding the behavior of many body quantum systems interacting with very short range potential, whose dynamics can be approximated by non linear Schr{\"o}dinger equations with singular interactions. In this work we proved that, in the case of one point interaction in $\mathbb{R}^3$, the perturbed Laplacian satisfies the same $L^p$-$L^q$ estimates of the free Laplacian in the smaller regime $q \in [2,3)$. These estimates are implied by a recent result concerning the Lpboundedness of the wave operators for the perturbed Laplacian. Our approach, however, is more direct and relatively simple, and could potentially be useful to prove optimal weighted estimates also in the regime $q \geq 3$.

}, isbn = {978-3-319-58904-6}, doi = {10.1007/978-3-319-58904-6_11}, url = {https://doi.org/10.1007/978-3-319-58904-6_11}, author = {Felice Iandoli and Raffaele Scandone}, editor = {Alessandro Michelangeli and Gianfausto Dell{\textquoteright}Antonio} } @inbook {Olgiati2017, title = {Effective Non-linear Dynamics of Binary Condensates and Open Problems}, booktitle = {Advances in Quantum Mechanics: Contemporary Trends and Open Problems}, year = {2017}, pages = {239{\textendash}256}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {We report on a recent result concerning the effective dynamics for a mixture of Bose-Einstein condensates, a class of systems much studied in physics and receiving a large amount of attention in the recent literature in mathematical physics; for such models, the effective dynamics is described by a coupled system of non-linear Sch{\"o}dinger equations. After reviewing and commenting our proof in the mean-field regime from a previous paper, we collect the main details needed to obtain the rigorous derivation of the effective dynamics in the Gross-Pitaevskii scaling limit.

}, isbn = {978-3-319-58904-6}, doi = {10.1007/978-3-319-58904-6_14}, url = {https://doi.org/10.1007/978-3-319-58904-6_14}, author = {Alessandro Olgiati}, editor = {Alessandro Michelangeli and Gianfausto Dell{\textquoteright}Antonio} } @article {2017, title = {Gamma-Convergence of Free-discontinuity problems}, number = {SISSA;18/2017/MATE}, year = {2017}, institution = {SISSA}, abstract = {We study the Gamma-convergence of sequences of free-discontinuity functionals depending on vector-valued functions u which can be discontinuous across hypersurfaces whose shape and location are not known a priori. The main novelty of our result is that we work under very general assumptions on the integrands which, in particular, are not required to be periodic in the space variable. Further, we consider the case of surface integrands which are not bounded from below by the amplitude of the jump of u. We obtain three main results: compactness with respect to Gamma-convergence, representation of the Gamma-limit in an integral form and identification of its integrands, and homogenisation formulas without periodicity assumptions. In particular, the classical case of periodic homogenisation follows as a by-product of our analysis. Moreover, our result covers also the case of stochastic homogenisation, as we will show in a forthcoming paper.}, url = {http://preprints.sissa.it/handle/1963/35276}, author = {Filippo Cagnetti and Gianni Dal Maso and Lucia Scardia and Caterina Ida Zeppieri} } @article { refId0, title = {On the genesis of directional friction through bristle-like mediating elements}, journal = {ESAIM: COCV}, volume = {23}, number = {3}, year = {2017}, pages = {1023-1046}, abstract = {We propose an explanation of the genesis of directional dry friction, as emergent property of the oscillations produced in a bristle-like mediating element by the interaction with microscale fluctuations on the surface. Mathematically, we extend a convergence result by Mielke, for Prandtl{\textendash}Tomlinson-like systems, considering also non-homothetic scalings of a wiggly potential. This allows us to apply the result to some simple mechanical models, that exemplify the interaction of a bristle with a surface having small fluctuations. We find that the resulting friction is the product of two factors: a geometric one, depending on the bristle angle and on the fluctuation profile, and a energetic one, proportional to the normal force exchanged between the bristle-like element and the surface. Finally, we apply our result to discuss the with the nap/against the nap asymmetry.

}, doi = {10.1051/cocv/2017030}, url = {https://doi.org/10.1051/cocv/2017030}, author = {Paolo Gidoni and Antonio DeSimone} } @article {2017arXiv170707595A, title = {The injectivity radius of Lie manifolds}, journal = {ArXiv e-prints}, year = {2017}, abstract = {We prove in a direct, geometric way that for any compatible Riemannian metric on a Lie manifold the injectivity radius is positive

}, keywords = {(58J40), 53C21, Mathematics - Differential Geometry}, url = {https://arxiv.org/pdf/1707.07595.pdf}, author = {Paolo Antonini and Guido De Philippis and Nicola Gigli} } @article {2017, title = {Linearisation of multiwell energies}, number = {SISSA;31/2017/MATE}, year = {2017}, abstract = {Linear elasticity can be rigorously derived from finite elasticity under the assumption of small loadings in terms of Gamma-convergence. This was first done in the case of one-well energies with super-quadratic growth and later generalised to different settings, in particular to the case of multi-well energies where the distance between the wells is very small (comparable to the size of the load). In this paper we study the case when the distance between the wells is independent of the size of the load. In this context linear elasticity can be derived by adding to the multi-well energy a singular higher order term which penalises jumps from one well to another. The size of the singular term has to satisfy certain scaling assumptions whose optimality is shown in most of the cases. Finally, the derivation of linear elasticty from a two-well discrete model is provided, showing that the role of the singular perturbation term is played in this setting by interactions beyond nearest neighbours.}, url = {http://preprints.sissa.it/handle/1963/35288}, author = {Roberto Alicandro and Gianni Dal Maso and Giuliano Lazzaroni and Mariapia Palombaro} } @article {dal2017lower, title = {Lower semicontinuity of a class of integral functionals on the space of functions of bounded deformation}, journal = {Advances in Calculus of Variations}, volume = {10}, number = {2}, year = {2017}, pages = {183{\textendash}207}, publisher = {De Gruyter}, abstract = {We study the lower semicontinuity of some free discontinuity functionals with linear growth defined on the space of functions with bounded deformation. The volume term is convex and depends only on the Euclidean norm of the symmetrized gradient. We introduce a suitable class of surface terms, which make the functional lower semicontinuous with respect to $L^1$ convergence.

}, doi = {10.1515/acv-2015-0036}, author = {Gianni Dal Maso and Gianluca Orlando and Rodica Toader} } @article {2015, title = {A lower semicontinuity result for a free discontinuity functional with a boundary term}, journal = {Journal de Math{\'e}matiques Pures et Appliqu{\'e}es}, volume = {108}, year = {2017}, pages = {952-990}, chapter = {952}, abstract = {We study the lower semicontinuity in $GSBV^{p}(\Omega;\mathbb{R}^{m})$ of a free discontinuity functional $\mathcal{F}(u)$ that can be written as the sum of a crack term, depending only on the jump set $S_{u}$, and of a boundary term, depending on the trace of $u$ on $\partial\Omega$. We give sufficient conditions on the integrands for the lower semicontinuity of $\mathcal{F}$. Moreover, we prove a relaxation result, which shows that, if these conditions are not satisfied, the lower semicontinuous envelope of $\mathcal{F}$ can be represented by the sum of two integrals on $S_{u}$ and $\partial\Omega$, respectively.

}, doi = {10.1016/j.matpur.2017.05.018}, url = {http://hdl.handle.net/20.500.11767/15979}, author = {Stefano Almi and Gianni Dal Maso and Rodica Toader} } @article {20.500.11767_11953, title = {A natural framework for isogeometric fluid-structure interaction based on BEM-shell coupling}, journal = {COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING}, volume = {316}, year = {2017}, pages = {522{\textendash}546}, doi = {10.1016/j.cma.2016.08.008}, url = {http://cdsads.u-strasbg.fr/abs/2017CMAME.316..522H}, author = {Luca Heltai and Kiendl, J. and Antonio DeSimone and Alessandro Reali} } @inbook {Olgiati2017, title = {Remarks on the Derivation of Gross-Pitaevskii Equation with Magnetic Laplacian}, booktitle = {Advances in Quantum Mechanics: Contemporary Trends and Open Problems}, year = {2017}, pages = {257{\textendash}266}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {The effective dynamics for a Bose-Einstein condensate in the regime of high dilution and subject to an external magnetic field is governed by a magnetic Gross-Pitaevskii equation. We elucidate the steps needed to adapt to the magnetic case the proof of the derivation of the Gross-Pitaevskii equation within the {\textquoteleft}{\textquoteleft}projection counting{\textquoteright}{\textquoteright} scheme.

}, isbn = {978-3-319-58904-6}, doi = {10.1007/978-3-319-58904-6_15}, url = {https://doi.org/10.1007/978-3-319-58904-6_15}, author = {Alessandro Olgiati}, editor = {Alessandro Michelangeli and Gianfausto Dell{\textquoteright}Antonio} } @article {Gidoni2017, title = {Stasis domains and slip surfaces in the locomotion of a bio-inspired two-segment crawler}, journal = {Meccanica}, volume = {52}, number = {3}, year = {2017}, month = {Feb}, pages = {587{\textendash}601}, abstract = {We formulate and solve the locomotion problem for a bio-inspired crawler consisting of two active elastic segments (i.e., capable of changing their rest lengths), resting on three supports providing directional frictional interactions. The problem consists in finding the motion produced by a given, slow actuation history. By focusing on the tensions in the elastic segments, we show that the evolution laws for the system are entirely analogous to the flow rules of elasto-plasticity. In particular, sliding of the supports and hence motion cannot occur when the tensions are in the interior of certain convex regions (stasis domains), while support sliding (and hence motion) can only take place when the tensions are on the boundary of such regions (slip surfaces). We solve the locomotion problem explicitly in a few interesting examples. In particular, we show that, for a suitable range of the friction parameters, specific choices of the actuation strategy can lead to net displacements also in the direction of higher friction.

}, issn = {1572-9648}, doi = {10.1007/s11012-016-0408-0}, url = {https://doi.org/10.1007/s11012-016-0408-0}, author = {Paolo Gidoni and Antonio DeSimone} } @article {PhysRevLett.119.033901, title = {Universality of the Peregrine Soliton in the Focusing Dynamics of the Cubic Nonlinear Schr{\"o}dinger Equation}, journal = {Phys. Rev. Lett.}, volume = {119}, year = {2017}, month = {Jul}, pages = {033901}, publisher = {American Physical Society}, doi = {10.1103/PhysRevLett.119.033901}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.119.033901}, author = {Tikan, Alexey and Billet, Cyril and Gennady El and Alexander Tovbis and Marco Bertola and Sylvestre, Thibaut and Gustave, Francois and Randoux, Stephane and Genty, Go{\"e}ry and Suret, Pierre and Dudley, John M.} } @article {MolaHeltaiDeSimone2017, title = {Wet and Dry Transom Stern Treatment for Unsteady and Nonlinear Potential Flow Model for Naval Hydrodynamics Simulations}, journal = {Journal of Ship Research}, volume = {61}, number = {1}, year = {2017}, pages = {1{\textendash}14}, abstract = {We present a model for the fast evaluation of the total drag of ship hulls operating in both wet and dry transom stern conditions, in calm or wavy water, based on the combination of an unsteady semi-Lagrangian potential flow formulation with fully nonlinear free-surface treatment, experimental correlations, and simplified viscous drag modeling. The implementation is entirely based on open source libraries. The spatial discretization is solved using a streamline upwind Petrov-Galerkin stabilization of an iso-parametric, collocation based, boundary element method, implemented using the open source library deal.II. The resulting nonlinear differential-algebraic system is integrated in time using implicit backward differentiation formulas, implemented in the open source library SUNDIALS. The Open CASCADE library is used to interface the model directly with computer-aided design data structures. The model accounts automatically for hulls with a transom stern, both in wet and dry regimes, by using a specific treatment of the free-surface nodes on the stern edge that automatically detects when the hull advances at low speeds. In this case, the transom stern is partially immersed, and a pressure patch is applied on the water surface detaching from the transom stern, to recover the gravity effect of the recirculating water on the underlying irrotational flow domain. The parameters of the model used to impose the pressure patch are approximated from experimental relations found in the literature. The test cases considered are those of the U.S. Navy Combatant DTMB-5415 and the National Physical Laboratory hull. Comparisons with experimental data on quasi-steady test cases for both water elevation and total hull drag are presented and discussed. The quality of the results obtained on quasi-steady simulations suggests that this model can represent a promising alternative to current unsteady solvers for simulations with Froude numbers below 0.35.

}, doi = {https://doi.org/10.5957/JOSR.61.1.160016}, author = {Andrea Mola and Luca Heltai and Antonio DeSimone} } @article {MR3505204, title = {Correlation functions of the KdV hierarchy and applications to intersection numbers over $\overline\CalM_g,n$}, journal = {Phys. D}, volume = {327}, year = {2016}, pages = {30{\textendash}57}, issn = {0167-2789}, doi = {10.1016/j.physd.2016.04.008}, url = {http://dx.doi.org/10.1016/j.physd.2016.04.008}, author = {Marco Bertola and Boris Dubrovin and Di Yang} } @article {20.500.11767_14498, title = {The deal.II library, Version 8.4}, journal = {JOURNAL OF NUMERICAL MATHEMATICS}, volume = {24}, year = {2016}, pages = {135{\textendash}141}, doi = {10.1515/jnma-2016-1045}, url = {https://www.math.clemson.edu/ heister/preprints/deal84-preprint.pdf}, author = {W. Bangerth and Denis Davydov and Timo Heister and Luca Heltai and G. Kanschat and Martin Kronbichler and Matthias Maier and B. Turcksin and David Wells} } @article {DALMASO20164897, title = {Existence and uniqueness of dynamic evolutions for a peeling test in dimension one}, journal = {Journal of Differential Equations}, volume = {261}, number = {9}, year = {2016}, pages = {4897 - 4923}, abstract = {In this paper we present a one-dimensional model of a dynamic peeling test for a thin film, where the wave equation is coupled with a Griffith criterion for the propagation of the debonding front. Our main results provide existence and uniqueness for the solution to this coupled problem under different assumptions on the data.

}, keywords = {Dynamic debonding, Dynamic energy release rate, Dynamic fracture, Griffith{\textquoteright}s criterion, Maximum dissipation principle, Wave equation in time-dependent domains}, issn = {0022-0396}, doi = {https://doi.org/10.1016/j.jde.2016.07.012}, url = {http://www.sciencedirect.com/science/article/pii/S0022039616301772}, author = {Gianni Dal Maso and Giuliano Lazzaroni and Lorenzo Nardini} } @article {DalMaso2016, title = {Fracture models for elasto-plastic materials as limits of gradient damage models coupled with plasticity: the antiplane case}, journal = {Calculus of Variations and Partial Differential Equations}, volume = {55}, number = {3}, year = {2016}, month = {Apr}, pages = {45}, abstract = {We study the asymptotic behavior of a variational model for damaged elasto-plastic materials in the case of antiplane shear. The energy functionals we consider depend on a small parameter $\varepsilon$, which forces damage concentration on regions of codimension one. We determine the $\Gamma$-limit as $\varepsilon$ tends to zero and show that it contains an energy term involving the crack opening.

}, issn = {1432-0835}, doi = {10.1007/s00526-016-0981-z}, url = {https://doi.org/10.1007/s00526-016-0981-z}, author = {Gianni Dal Maso and Gianluca Orlando and Rodica Toader} } @article {2016, title = {A model for the quasistatic growth of cracks with fractional dimension}, number = {SISSA;10/2016/MATE}, year = {2016}, abstract = {We study a variational model for the quasistatic growth of cracks with fractional dimension in brittle materials. We give a minimal set of properties of the collection of admissible cracks which ensure the existence of a quasistatic evolution. Both the antiplane and the planar cases are treated.}, url = {http://urania.sissa.it/xmlui/handle/1963/35175}, author = {Gianni Dal Maso and Marco Morandotti} } @article {Cicconofri2016, title = {Motion planning and motility maps for flagellar microswimmers}, journal = {The European Physical Journal E}, volume = {39}, number = {7}, year = {2016}, month = {Jul}, pages = {72}, abstract = {We study two microswimmers consisting of a spherical rigid head and a passive elastic tail. In the first one the tail is clamped to the head, and the system oscillates under the action of an external torque. In the second one, head and tail are connected by a joint allowing the angle between them to vary periodically, as a result of an oscillating internal torque. Previous studies on these models were restricted to sinusoidal actuations, showing that the swimmers can propel while moving on average along a straight line, in the direction given by the symmetry axis around which beating takes place. We extend these results to motions produced by generic (non-sinusoidal) periodic actuations within the regime of small compliance of the tail. We find that modulation in the velocity of actuation can provide a mechanism to select different directions of motion. With velocity-modulated inputs, the externally actuated swimmer can translate laterally with respect to the symmetry axis of beating, while the internally actuated one is able to move along curved trajectories. The governing equations are analysed with an asymptotic perturbation scheme, providing explicit formulas, whose results are expressed through motility maps. Asymptotic approximations are further validated by numerical simulations.

}, issn = {1292-895X}, doi = {10.1140/epje/i2016-16072-y}, url = {https://doi.org/10.1140/epje/i2016-16072-y}, author = {Giancarlo Cicconofri and Antonio DeSimone} } @inbook {Arici2016, title = {Pimsner Algebras and Circle Bundles}, booktitle = {Noncommutative Analysis, Operator Theory and Applications}, year = {2016}, pages = {1{\textendash}25}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {We report on the connections between noncommutative principal circle bundles, Pimsner algebras and strongly graded algebras. We illustrate several results with examples of quantum weighted projective and lens spaces and θ-deformations.

}, isbn = {978-3-319-29116-1}, doi = {10.1007/978-3-319-29116-1_1}, url = {https://doi.org/10.1007/978-3-319-29116-1_1}, author = {Francesca Arici and Francesco D{\textquoteright}Andrea and Giovanni Landi}, editor = {Alpay, Daniel and Cipriani, Fabio and Colombo, Fabrizio and Guido, Daniele and Sabadini, Irene and Sauvageot, Jean-Luc} } @conference {mola2016ship, title = {Ship Sinkage and Trim Predictions Based on a CAD Interfaced Fully Nonlinear Potential Model}, booktitle = {The 26th International Ocean and Polar Engineering Conference}, volume = {3}, year = {2016}, pages = {511{\textendash}518}, publisher = {International Society of Offshore and Polar Engineers}, organization = {International Society of Offshore and Polar Engineers}, author = {Andrea Mola and Luca Heltai and Antonio DeSimone and Massimiliano Berti} } @article {BertoDiDub, title = {Simple Lie Algebras and Topological ODEs}, journal = {Int. Math. Res. Not.}, volume = {2016}, number = {rnw285}, year = {2016}, author = {Marco Bertola and Boris Dubrovin and Di Yang} } @article {2016, title = {On the third critical speed for rotating Bose-Einstein condensates}, journal = {Correggi, M., Dimonte, D., 2016. On the third critical speed for rotating Bose-Einstein condensates. J. Math. Phys. 57, 71901}, number = {Journal of Mathematical Physics;57}, year = {2016}, publisher = {AIP Publisher}, abstract = {We study a two-dimensional rotating Bose-Einstein condensate confined by an anharmonic trap in the framework of the Gross-Pitaevskii theory. We consider a rapid rotation regime close to the transition to a giant vortex state. It was proven in Correggi et al. [J. Math. Phys. 53, 095203 (2012)] that such a transition occurs when the angular velocity is of order ε-4, with ε-2 denoting the coefficient of the nonlinear term in the Gross-Pitaevskii functional and ε << 1 (Thomas-Fermi regime). In this paper, we identify a finite value Ωc such that if Ω = Ω0/ε4 with Ω0 > Ωc, the condensate is in the giant vortex phase. Under the same condition, we prove a refined energy asymptotics and an estimate of the winding number of any Gross-Pitaevskii minimizer.}, doi = {10.1063/1.4954805}, url = {http://urania.sissa.it/xmlui/handle/1963/35246}, author = {Daniele Dimonte and Michele Correggi} } @article {2015, title = {A class of Hamiltonians for a three-particle fermionic system at unitarity}, year = {2015}, note = {This SISSA preprint is composed of 29 pages and is recorded in PDF format}, abstract = {We consider a quantum mechanical three-particle system made of two identical fermions of mass one and a different particle of mass $m$, where each fermion interacts via a zero-range force with the different particle. In particular we study the unitary regime, i.e., the case of infinite two-body scattering length. The Hamiltonians describing the system are, by definition, self-adjoint extensions of the free Hamiltonian restricted on smooth functions vanishing at the two-body coincidence planes, i.e., where the positions of two interacting particles coincide. It is known that for $m$ larger than a critical value $m^* \simeq (13.607)^{-1}$ a self-adjoint and lower bounded Hamiltonian $H_0$ can be constructed, whose domain is characterized in terms of the standard point-interaction boundary condition at each coincidence plane. Here we prove that for $m\in(m^*,m^{**})$, where $m^{**}\simeq (8.62)^{-1}$, there is a further family of self-adjoint and lower bounded Hamiltonians $H_{0,\beta}$, $\beta \in \mathbb{R}$, describing the system. Using a quadratic form method, we give a rigorous construction of such Hamiltonians and we show that the elements of their domains satisfy a further boundary condition, characterizing the singular behavior when the positions of all the three particles coincide.}, url = {http://urania.sissa.it/xmlui/handle/1963/34469}, author = {Michele Correggi and Gianfausto Dell{\textquoteright}Antonio and Domenico Finco and Alessandro Michelangeli and Alessandro Teta} } @article {2015, title = {Existence for constrained dynamic Griffith fracture with a weak maximal dissipation condition}, year = {2015}, abstract = {There are very few existence results for fracture evolution, outside of globally minimizing quasi-static evolutions. Dynamic evolutions are particularly problematic, due to the difficulty of showing energy balance, as well as of showing that solutions obey a maximal dissipation condition, or some similar condition that prevents stationary cracks from always being solutions. Here we introduce a new weak maximal dissipation condition and show that it is compatible with cracks constrained to grow smoothly on a smooth curve. In particular, we show existence of dynamic fracture evolutions satisfying this maximal dissipation condition, subject to the above smoothness constraints, and exhibit explicit examples to show that this maximal dissipation principle can indeed rule out stationary cracks as solutions.}, url = {http://urania.sissa.it/xmlui/handle/1963/35045}, author = {Gianni Dal Maso and Cristopher J. Larsen and Rodica Toader} } @conference {calore2015experience, title = {Experience on vectorizing lattice Boltzmann kernels for multi-and many-core architectures}, booktitle = {International Conference on Parallel Processing and Applied Mathematics}, year = {2015}, pages = {53{\textendash}62}, publisher = {Springer}, organization = {Springer}, author = {Calore, Enrico and Nicola Demo and Schifano, Sebastiano Fabio and Tripiccione, Raffaele} } @article {2015, title = {Extended affine Weyl groups of BCD type, Frobenius manifolds and their Landau-Ginzburg superpotentials}, year = {2015}, institution = {SISSA}, abstract = {For the root systems of type Bl, Cl and Dl, we generalize the result of [7] by showing the existence of Frobenius manifold structures on the orbit spaces of the extended affine Weyl groups that correspond to any vertex of the Dynkin diagram instead of a particular choice made in [7]. It also depends on certain additional data. We also construct LG superpotentials for these Frobenius manifold structures.}, url = {http://preprints.sissa.it/handle/1963/35316}, author = {Boris Dubrovin and Ian A.B. Strachan and Youjin Zhang and Dafeng Zuo} } @article {DESIMONE2015254, title = {Liquid crystal elastomer strips as soft crawlers}, journal = {Journal of the Mechanics and Physics of Solids}, volume = {84}, year = {2015}, pages = {254 - 272}, abstract = {In this paper, we speculate on a possible application of Liquid Crystal Elastomers to the field of soft robotics. In particular, we study a concept for limbless locomotion that is amenable to miniaturisation. For this purpose, we formulate and solve the evolution equations for a strip of nematic elastomer, subject to directional frictional interactions with a flat solid substrate, and cyclically actuated by a spatially uniform, time-periodic stimulus (e.g., temperature change). The presence of frictional forces that are sensitive to the direction of sliding transforms reciprocal, {\textquoteleft}breathing-like{\textquoteright} deformations into directed forward motion. We derive formulas quantifying this motion in the case of distributed friction, by solving a differential inclusion for the displacement field. The simpler case of concentrated frictional interactions at the two ends of the strip is also solved, in order to provide a benchmark to compare the continuously distributed case with a finite-dimensional benchmark. We also provide explicit formulas for the axial force along the crawler body.

}, keywords = {Crawling motility, Directional surfaces, Frictional interactions, Liquid crystal elastomers, Soft biomimetic robots}, issn = {0022-5096}, doi = {https://doi.org/10.1016/j.jmps.2015.07.017}, url = {http://www.sciencedirect.com/science/article/pii/S0022509615300430}, author = {Antonio DeSimone and Paolo Gidoni and Giovanni Noselli} } @article {CICCONOFRI2015233, title = {Motility of a model bristle-bot: A theoretical analysis}, journal = {International Journal of Non-Linear Mechanics}, volume = {76}, year = {2015}, pages = {233 - 239}, abstract = {Bristle-bots are legged robots that can be easily made out of a toothbrush head and a small vibrating engine. Despite their simple appearance, the mechanism enabling them to propel themselves by exploiting friction with the substrate is far from trivial. Numerical experiments on a model bristle-bot have been able to reproduce such a mechanism revealing, in addition, the ability to switch direction of motion by varying the vibration frequency. This paper provides a detailed account of these phenomena through a fully analytical treatment of the model. The equations of motion are solved through an expansion in terms of a properly chosen small parameter. The convergence of the expansion is rigorously proven. In addition, the analysis delivers formulas for the average velocity of the robot and for the frequency at which the direction switch takes place. A quantitative description of the mechanism for the friction modulation underlying the motility of the bristle-bot is also provided.

}, keywords = {Bristle-robots, Crawling motility, Frictional interactions}, issn = {0020-7462}, doi = {https://doi.org/10.1016/j.ijnonlinmec.2014.12.010}, url = {http://www.sciencedirect.com/science/article/pii/S0020746215000025}, author = {Giancarlo Cicconofri and Antonio DeSimone} } @article {2015, title = {The phototransduction machinery in the rod outer segment has a strong efficacy gradient}, number = {Proceedings of the National Academy of Sciences of the United States of America;Volume 112, issue 20; pp. E2715-E2724}, year = {2015}, note = {Open Access article}, publisher = {National Academy of Sciences}, doi = {10.1073/pnas.1423162112}, url = {http://urania.sissa.it/xmlui/handle/1963/35157}, author = {Monica Mazzolini and Giuseppe Facchetti and L. Andolfi and R. Proietti Zaccaria and S. Tuccio and J. Treud and Claudio Altafini and Enzo M. Di Fabrizio and Marco Lazzarino and G. Rapp and Vincent Torre} } @article {2015, title = {Sch{\"o}dinger operators on half-line with shrinking potentials at the origin}, number = {SISSA;06/2015/MATE}, year = {2015}, institution = {SISSA}, abstract = {We discuss the general model of a Schr{\"o}dinger quantum particle constrained on a straight half-line with given self-adjoint boundary condition at the origin and an interaction potential supported around the origin. We study the limit when the range of the potential scales to zero and its magnitude blows up. We show that in the limit the dynamics is generated by a self-adjoint negative Laplacian on the half-line, with a possible preservation or modification of the boundary condition at the origin, depending on the magnitude of the scaling and of the strength of the potential.}, url = {http://urania.sissa.it/xmlui/handle/1963/34439}, author = {Gianfausto Dell{\textquoteright}Antonio and Alessandro Michelangeli} } @article {doi:10.1098/rspa.2015.0054, title = {A study of snake-like locomotion through the analysis of a flexible robot model}, journal = {Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences}, volume = {471}, number = {2184}, year = {2015}, pages = {20150054}, abstract = {We examine the problem of snake-like locomotion by studying a system consisting of a planar inextensible elastic rod with adjustable spontaneous curvature, which provides an internal actuation mechanism that mimics muscular action in a snake. Using a Cosserat model, we derive the equations of motion in two special cases: one in which the rod can only move along a prescribed curve, and one in which the rod is constrained to slide longitudinally without slipping laterally, but the path is not fixed a priori (free-path case). The second setting is inspired by undulatory locomotion of snakes on flat surfaces. The presence of constraints leads in both cases to non-standard boundary conditions that allow us to close and solve the equations of motion. The kinematics and dynamics of the system can be recovered from a one-dimensional equation, without any restrictive assumption on the followed trajectory or the actuation. We derive explicit formulae highlighting the role of spontaneous curvature in providing the driving force (and the steering, in the free-path case) needed for locomotion. We also provide analytical solutions for a special class of serpentine motions, which enable us to discuss the connection between observed trajectories, internal actuation and forces exchanged with the environment.

}, doi = {10.1098/rspa.2015.0054}, url = {https://royalsocietypublishing.org/doi/abs/10.1098/rspa.2015.0054}, author = {Giancarlo Cicconofri and Antonio DeSimone} } @article {2015, title = {Three-sphere low-Reynolds-number swimmer with a passive elastic arm}, number = {European Physical Journal E; Volume 38; Issue 5; Article number 42}, year = {2015}, publisher = {Springer}, abstract = {One of the simplest model swimmers at low Reynolds number is the three-sphere swimmer by Najafi and Golestanian. It consists of three spheres connected by two rods which change their lengths periodically in non-reciprocal fashion. Here we investigate a variant of this model in which one rod is periodically actuated while the other is replaced by an elastic spring. We show that the competition between the elastic restoring force and the hydrodynamic drag produces a delay in the response of the passive elastic arm with respect to the active one. This leads to non-reciprocal shape changes and self-propulsion. After formulating the equations of motion, we study their solutions qualitatively and numerically. The leading-order term of the solution is computed analytically. We then address questions of optimization with respect to both actuation frequency and swimmer{\textquoteright}s geometry. Our results can provide valuable conceptual guidance in the engineering of robotic microswimmers.}, doi = {10.1140/epje/i2015-15042-3}, url = {http://urania.sissa.it/xmlui/handle/1963/34530}, author = {Alessandro Montino and Antonio DeSimone} } @article {2015, title = {The wave equation on domains with cracks growing on a prescribed path: existence, uniqueness, and continuous dependence on the data}, number = {SISSA;47/2015/MATE}, year = {2015}, abstract = {Given a bounded open set $\Omega \subset \mathbb R^d$ with Lipschitz boundary and an increasing family $\Gamma_t$, $t\in [0,T]$, of closed subsets of $\Omega$, we analyze the scalar wave equation $\ddot{u} - div (A \nabla u) = f$ in the time varying cracked domains $\Omega\setminus\Gamma_t$. Here we assume that the sets $\Gamma_t$ are contained into a prescribed $(d-1)$-manifold of class $C^2$. Our approach relies on a change of variables: recasting the problem on the reference configuration $\Omega\setminus \Gamma_0$, we are led to consider a hyperbolic problem of the form $\ddot{v} - div (B\nabla v) + a \cdot \nabla v - 2 b \cdot \nabla \dot{v} = g$ in $\Omega \setminus \Gamma_0$. Under suitable assumptions on the regularity of the change of variables that transforms $\Omega\setminus \Gamma_t$ into $\Omega\setminus \Gamma_0$, we prove existence and uniqueness of weak solutions for both formulations. Moreover, we provide an energy equality, which gives, as a by-product, the continuous dependence of the solutions with respect to the cracks.}, url = {http://urania.sissa.it/xmlui/handle/1963/34629}, author = {Gianni Dal Maso and Ilaria Lucardesi} } @article {2014, title = {Adler-Gelfand-Dickey approach to classical W-algebras within the theory of Poisson vertex algebras}, number = {arXiv:1401.2082}, year = {2014}, note = {45 pages}, publisher = {SISSA}, abstract = {We put the Adler-Gelfand-Dickey approach to classical W-algebras in the framework of Poisson vertex algebras. We show how to recover the bi-Poisson structure of the KP hierarchy, together with its generalizations and reduction to the N-th KdV hierarchy, using the formal distribution calculus and the lambda-bracket formalism. We apply the Lenard-Magri scheme to prove integrability of the corresponding hierarchies. We also give a simple proof of a theorem of Kupershmidt and Wilson in this framework. Based on this approach, we generalize all these results to the matrix case. In particular, we find (non-local) bi-Poisson structures of the matrix KP and the matrix N-th KdV hierarchies, and we prove integrability of the N-th matrix KdV hierarchy.}, url = {http://hdl.handle.net/1963/7242}, author = {Alberto De Sole and Victor G. Kac and Daniele Valeri} } @article {2013, title = {Classical W-algebras and generalized Drinfeld-Sokolov hierarchies for minimal and short nilpotents}, journal = {Communications in Mathematical Physics 331, nr. 2 (2014) 623-676}, number = {arXiv:1306.1684;}, year = {2014}, note = {46 pages}, publisher = {SISSA}, abstract = {We derive explicit formulas for lambda-brackets of the affine classical W-algebras attached to the minimal and short nilpotent elements of any simple Lie algebra g. This is used to compute explicitly the first non-trivial PDE of the corresponding intgerable generalized Drinfeld-Sokolov hierarchies. It turns out that a reduction of the equation corresponding to a short nilpotent is Svinolupov{\textquoteright}s equation attached to a simple Jordan algebra, while a reduction of the equation corresponding to a minimal nilpotent is an integrable Hamiltonian equation on 2h-3 functions, where h is the dual Coxeter number of g. In the case when g is sl_2 both these equations coincide with the KdV equation. In the case when g is not of type C_n, we associate to the minimal nilpotent element of g yet another generalized Drinfeld-Sokolov hierarchy.}, doi = {10.1007/s00220-014-2049-2}, url = {http://hdl.handle.net/1963/6979}, author = {Alberto De Sole and Victor G. Kac and Daniele Valeri} } @article {GIDONI201465, title = {Crawling on directional surfaces}, journal = {International Journal of Non-Linear Mechanics}, volume = {61}, year = {2014}, pages = {65 - 73}, abstract = {In this paper we study crawling locomotion based on directional frictional interactions, namely, frictional forces that are sensitive to the sign of the sliding velocity. Surface interactions of this type are common in biology, where they arise from the presence of inclined hairs or scales at the crawler/substrate interface, leading to low resistance when sliding {\textquoteleft}along the grain{\textquoteright}, and high resistance when sliding {\textquoteleft}against the grain{\textquoteright}. This asymmetry can be exploited for locomotion, in a way analogous to what is done in cross-country skiing (classic style, diagonal stride). We focus on a model system, namely, a continuous one-dimensional crawler and provide a detailed study of the motion resulting from several strategies of shape change. In particular, we provide explicit formulae for the displacements attainable with reciprocal extensions and contractions (breathing), or through the propagation of extension or contraction waves. We believe that our results will prove particularly helpful for the study of biological crawling motility and for the design of bio-mimetic crawling robots.

}, keywords = {Bio-mimetic micro-robots, Cell migration, Crawling motility, Directional surfaces, Self-propulsion}, issn = {0020-7462}, doi = {https://doi.org/10.1016/j.ijnonlinmec.2014.01.012}, url = {http://www.sciencedirect.com/science/article/pii/S0020746214000213}, author = {Paolo Gidoni and Giovanni Noselli and Antonio DeSimone} } @article {2014, title = {Curvature-adapted remeshing of CAD surfaces}, journal = {Procedia Engineering}, volume = {82}, number = {Procedia Engineering;volume 82; issue C; pages 253-265;}, year = {2014}, note = {This is an open access article under the CC BY-NC-ND license}, pages = {253{\textendash}265}, publisher = {Elsevier}, abstract = {A common representation of surfaces with complicated topology and geometry is through composite parametric surfaces as is the case for most CAD modelers. A challenging problem is how to generate a mesh of such a surface that well approximates the geometry of the surface, preserves its topology and important geometric features, and contains nicely shaped elements. In this work, we present an optimization-based surface remeshing method that is able to satisfy many of these requirements simultaneously. This method is inspired by the recent work of L{\'e}vy and Bonneel (Proc. 21th International Meshing Roundtable, October 2012), which embeds a smooth surface into a high-dimensional space and remesh it uniformly in that embedding space. Our method works directly in the 3d spaces and uses an embedding space in R6 to evaluate mesh size and mesh quality. It generates a curvatureadapted anisotropic surface mesh that well represents the geometry of the surface with a low number of elements. We illustrate our approach through various examples.

}, doi = {10.1016/j.proeng.2014.10.388}, url = {https://doi.org/10.1016/j.proeng.2014.10.388}, author = {Franco Dassi and Andrea Mola and Hang Si} } @article {2014, title = {Dirac operators on noncommutative principal circle bundles}, number = {International Journal of Geometric Methods in Modern Physics;volume 11; issue 1; article number 1450012;}, year = {2014}, publisher = {World Scientific Publishing}, abstract = {We study spectral triples over noncommutative principal U(1)-bundles of arbitrary dimension and a compatibility condition between the connection and the Dirac operator on the total space and on the base space of the bundle. Examples of low-dimensional noncommutative tori are analyzed in more detail and all connections found that are compatible with an admissible Dirac operator. Conversely, a family of new Dirac operators on the noncommutative tori, which arise from the base-space Dirac operator and a suitable connection is exhibited. These examples are extended to the theta-deformed principal U(1)-bundle S 3 θ {\textrightarrow} S2.}, doi = {10.1142/S0219887814500121}, url = {http://urania.sissa.it/xmlui/handle/1963/35125}, author = {Andrzej Sitarz and Alessandro Zucca and Ludwik Dabrowski} } @article {2013, title = {Dirac reduction for Poisson vertex algebras}, journal = {Communications in Mathematical Physics 331, nr. 3 (2014) 1155-1190}, number = {arXiv:1306.6589;}, year = {2014}, note = {31 pages}, publisher = {SISSA}, abstract = {We construct an analogue of Dirac{\textquoteright}s reduction for an arbitrary local or non-local Poisson bracket in the general setup of non-local Poisson vertex algebras. This leads to Dirac{\textquoteright}s reduction of an arbitrary non-local Poisson structure. We apply this construction to an example of a generalized Drinfeld-Sokolov hierarchy.}, doi = {10.1007/s00220-014-2103-0}, url = {http://hdl.handle.net/1963/6980}, author = {Alberto De Sole and Victor G. Kac and Daniele Valeri} } @article {2014, title = {Discrete one-dimensional crawlers on viscous substrates: achievable net displacements and their energy cost}, number = {Mechanics Research Communications}, year = {2014}, publisher = {Elsevier}, abstract = {We study model one-dimensional crawlers, namely, model mechanical systems that can achieve self-propulsion by controlled shape changes of their body (extension or contraction of portions of the body), thanks to frictional interactions with a rigid substrate. We evaluate the achievable net displacement and the related energetic cost for self-propulsion by discrete crawlers (i.e., whose body is made of a discrete number of contractile or extensile segments) moving on substrates with either a Newtonian (linear) or a Bingham-type (stick-slip) rheology. Our analysis is aimed at constructing the basic building blocks towards an integrative, multi-scale description of crawling cell motility.}, keywords = {Cell migration}, doi = {10.1016/j.mechrescom.2013.10.023}, url = {http://urania.sissa.it/xmlui/handle/1963/34449}, author = {Giovanni Noselli and Amabile Tatone and Antonio DeSimone} } @article {2014, title = {Donagi{\textendash}Markman cubic for the generalised Hitchin system}, year = {2014}, abstract = {Donagi and Markman (1993) have shown that the infinitesimal period map for an algebraic completely integrable Hamiltonian system (ACIHS) is encoded in a section of the third symmetric power of the cotangent bundle to the base of the system. For the ordinary Hitchin system the cubic is given by a formula of Balduzzi and Pantev. We show that the Balduzzi{\textendash}Pantev formula holds on maximal rank symplectic leaves of the G-generalised Hitchin system.}, keywords = {Generalized Hitchin system, Donagi-Markman cubic, algebraically completely integrable systems, moduli space of Higgs G-bundles}, url = {http://hdl.handle.net/1963/7253}, author = {Ugo Bruzzo and Peter Dalakov} } @article {2014, title = {Dynamics on a graph as the limit of the dynamics on a "fat graph"}, number = {SISSA;69/2014/MATE}, year = {2014}, institution = {SISSA}, abstract = {We discuss how the vertex boundary conditions for the dynamics of a quantum particle constrained on a graph emerge in the limit of the dynamics of a particle in a tubular region around the graph (\fat graph") when the transversal section of this region shrinks to zero. We give evidence of the fact that if the limit dynamics exists and is induced by the Laplacian on the graph with certain self-adjoint boundary conditions, such conditions are determined by the possible presence of a zero energy resonance on the fat graph. Pictorially, one may say that in the shrinking limit the resonance acts as a bridge connecting the boundary values at the vertex along the different rays.}, url = {http://urania.sissa.it/xmlui/handle/1963/7485}, author = {Gianfausto Dell{\textquoteright}Antonio and Alessandro Michelangeli} } @article {2014, title = {Editorial}, number = {Rendiconti del circolo matematico di Palermo;volume 63; issue 3; pages 317-318;}, year = {2014}, publisher = {Springer}, doi = {10.1007/s12215-014-0172-8}, url = {http://urania.sissa.it/xmlui/handle/1963/34712}, author = {Ciro Ciliberto and Gianni Dal Maso and Pasquale Vetro} } @article {2014, title = {An effective model for nematic liquid crystal composites with ferromagnetic inclusions}, number = {SIAM Journal on Applied Mathematics;volume 74; issue 2; pages 237-262;}, year = {2014}, publisher = {Society for Industrial and Applied Mathematics Publications}, abstract = {Molecules of a nematic liquid crystal respond to an applied magnetic field by reorienting themselves in the direction of the field. Since the dielectric anisotropy of a nematic is small, it takes relatively large fields to elicit a significant liquid crystal response. The interaction may be enhanced in colloidal suspensions of ferromagnetic particles in a liquid crystalline matrix- ferronematics-as proposed by Brochard and de Gennes in 1970. The ability of these particles to align with the field and simultaneously cause reorientation of the nematic molecules greatly increases the magnetic response of the mixture. Essentially the particles provide an easy axis of magnetization that interacts with the liquid crystal via surface anchoring. We derive an expression for the effective energy of ferronematic in the dilute limit, that is, when the number of particles tends to infinity while their total volume fraction tends to zero. The total energy of the mixture is assumed to be the sum of the bulk elastic liquid crystal contribution, the anchoring energy of the liquid crystal on the surfaces of the particles, and the magnetic energy of interaction between the particles and the applied magnetic field. The homogenized limiting ferronematic energy is obtained rigorously using a variational approach. It generalizes formal expressions previously reported in the physical literature.}, doi = {10.1137/130910348}, url = {http://urania.sissa.it/xmlui/handle/1963/34940}, author = {Maria Carme Calderer and Antonio DeSimone and Dmitry Golovaty and Alexander Panchenko} } @article {2014, title = {Existence and uniqueness of the gradient flow of the Entropy in the space of probability measures}, number = {Rendiconti dell{\textquoteright}Istituto di Matematica dell{\textquoteright}Universita di Trieste;Volume 46; issue 1; pp. 43-70;}, year = {2014}, note = {This paper resumes the main part of the Bachelor thesis of the second author, discussed in 2013 at the University of Trieste.}, publisher = {EUT Edizioni Universita di Trieste}, abstract = {After a brief introduction on gradient flows in metric spaces and on geodesically convex functionals, we give an account of the proof (following the outline of [3, 7]) of the existence and uniqueness of the gradient flow of the Entropy in the space of Borel probability measures over a compact geodesic metric space with Ricci curvature bounded from below.}, url = {http://urania.sissa.it/xmlui/handle/1963/34693}, author = {Stefano Bianchini and Alexander Dabrowski} } @proceedings {2014, title = {A fully nonlinear potential model for ship hydrodynamics directly interfaced with CAD data structures}, year = {2014}, publisher = {SISSA}, abstract = {We present a model for ship hydrodynamics simulations currently under development at SISSA. The model employs potential flow theory and fully nonlinear free surface boundary conditions. The spatial discretization of the equations is performed by means of a collocation BEM. This gives rise to a Differential Algbraic Equations (DAE) system, solved using an implicit BDF scheme to time advance the solution. The model has been implemented into a C++ software able to automatically generate the computational grids from the CAD geometry of the hull. Numerical results on Kriso KCS and KVLCC2 hulls are presented and discussed.}, keywords = {ship hydrodynamics}, author = {Andrea Mola and Luca Heltai and Antonio DeSimone} } @article {2014, title = {Integrability of Dirac reduced bi-Hamiltonian equations}, number = {arXiv:1401.6006;}, year = {2014}, note = {15 pages}, institution = {SISSA}, abstract = {First, we give a brief review of the theory of the Lenard-Magri scheme for a non-local bi-Poisson structure and of the theory of Dirac reduction. These theories are used in the remainder of the paper to prove integrability of three hierarchies of bi-Hamiltonian PDE{\textquoteright}s, obtained by Dirac reduction from some generalized Drinfeld-Sokolov hierarchies.}, url = {http://hdl.handle.net/1963/7247}, author = {Alberto De Sole and Victor G. Kac and Daniele Valeri} } @article {2013, title = {On an isomonodromy deformation equation without the Painlev{\'e} property}, number = {Russian Journal of Mathematical Physics}, year = {2014}, note = {34 pages, 8 figures, references added}, publisher = {Maik Nauka-Interperiodica Publishing}, abstract = {We show that the fourth order nonlinear ODE which controls the pole dynamics in the general solution of equation $P_I^2$ compatible with the KdV equation exhibits two remarkable properties: 1) it governs the isomonodromy deformations of a $2\times2$ matrix linear ODE with polynomial coefficients, and 2) it does not possesses the Painlev\'e property. We also study the properties of the Riemann--Hilbert problem associated to this ODE and find its large $t$ asymptotic solution for the physically interesting initial data.}, doi = {10.1134/S1061920814010026}, url = {http://hdl.handle.net/1963/6466}, author = {Boris Dubrovin and Andrey Kapaev} } @article {2014, title = {Laplace equation in a domain with a rectilinear crack: higher order derivatives of the energy with respect to the crack length}, number = {Nonlinear Differential Equations and Applications}, year = {2014}, publisher = {SISSA}, abstract = {We consider the weak solution of the Laplace equation in a planar domain with a straight crack, prescribing a homogeneous Neumann condition on the crack and a nonhomogeneous Dirichlet condition on the rest of the boundary. For every k we express the k-th derivative of the energy with respect to the crack length in terms of a finite number of coefficients of the asymptotic expansion of the solution near the crack tip and of a finite number of other parameters, which only depend on the shape of the domain.

}, keywords = {cracked domains, energy release rate, higher order derivatives, asymptotic expansion of solutions}, doi = {10.1007/s00030-014-0291-0}, url = {http://hdl.handle.net/1963/7271}, author = {Gianni Dal Maso and Gianluca Orlando and Rodica Toader} } @inbook {2014, title = {Lecture notes on gradient flows and optimal transport}, number = {London Mathematical Society Lecture Note Series;volume 413; pages 100-144;}, year = {2014}, note = {Book title: Optimal transportation}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, abstract = {We present a short overview on the strongest variational formulation for gradient flows of geodesically λ-convex functionals in metric spaces, with applications to diffusion equations in Wasserstein spaces of probability measures. These notes are based on a series of lectures given by the second author for the Summer School "Optimal transportation: Theory and applications" in Grenoble during the week of June 22-26, 2009.}, doi = {10.1017/CBO9781107297296}, url = {http://urania.sissa.it/xmlui/handle/1963/35093}, author = {Sara Daneri and Giuseppe Savar{\`e}} } @article {davoli_2014, title = {Linearized plastic plate models as Γ-limits of 3D finite elastoplasticity}, journal = {ESAIM: Control, Optimisation and Calculus of Variations}, volume = {20}, number = {3}, year = {2014}, pages = {725{\textendash}747}, publisher = {EDP Sciences}, abstract = {The subject of this paper is the rigorous derivation of reduced models for a thin plate by means of $\Gamma$-convergence, in the framework of finite plasticity. Denoting by $\epsilon$ the thickness of the plate, we analyse the case where the scaling factor of the elasto-plastic energy per unit volume is of order $\epsilon^{2 \alpha -2}$, with $\alpha \geq 3$. According to the value of $\alpha$, partially or fully linearized models are deduced, which correspond, in the absence of plastic deformation, to the Von K{\'a}rm{\'a}n plate theory and the linearized plate theory.

}, doi = {10.1051/cocv/2013081}, author = {Elisa Davoli} } @article {11062, title = {Local behavior of fractional p-minimizers}, number = {SISSA preprint;10/2014/MATE}, year = {2014}, publisher = {SISSA}, abstract = {We extend the De Giorgi-Nash Moser theory to nonlocal, possibly degerate integro-differential operators

}, keywords = {fractional Sobolev spaces}, author = {Agnese Di Castro and Tuomo Kuusi and Giampiero Palatucci} } @article {2014, title = {Minimal Liouville gravity correlation numbers from Douglas string equation}, number = {Journal of high energy physics;volume 2014; issue 1; article number 156;}, year = {2014}, publisher = {Springer}, abstract = {We continue the study of $(q,p)$ Minimal Liouville Gravity with the help of Douglas string equation. We generalize the results of \cite{Moore:1991ir}, \cite{Belavin:2008kv}, where Lee-Yang series $(2,2s+1)$ was studied, to $(3,3s+p_0)$ Minimal Liouville Gravity, where $p_0=1,2$. We demonstrate that there exist such coordinates $\tau_{m,n}$ on the space of the perturbed Minimal Liouville Gravity theories, in which the partition function of the theory is determined by the Douglas string equation. The coordinates $\tau_{m,n}$ are related in a non-linear fashion to the natural coupling constants $\lambda_{m,n}$ of the perturbations of Minimal Lioville Gravity by the physical operators $O_{m,n}$. We find this relation from the requirement that the correlation numbers in Minimal Liouville Gravity must satisfy the conformal and fusion selection rules. After fixing this relation we compute three- and four-point correlation numbers when they are not zero. The results are in agreement with the direct calculations in Minimal Liouville Gravity available in the literature \cite{Goulian:1990qr}, \cite{Zamolodchikov:2005sj}, \cite{Belavin:2006ex}.}, doi = {10.1007/JHEP01(2014)156}, url = {http://urania.sissa.it/xmlui/handle/1963/34588}, author = {Alexander Belavin and Boris Dubrovin and Baur Mukhametzhanov} } @article {2012, title = {New results on Gamma-limits of integral functionals}, number = {Annales de l{\textquoteright}Institut Henri Poincare. Analyse Non Lineaire}, year = {2014}, publisher = {Elsevier}, keywords = {Gamma-convergence}, doi = {10.1016/j.anihpc.2013.02.005}, url = {http://hdl.handle.net/1963/5880}, author = {Nadia Ansini and Gianni Dal Maso and Caterina Ida Zeppieri} } @article {2012, title = {Nonsingular Isogeometric Boundary Element Method for Stokes Flows in 3D}, number = {Computer Methods in Applied Mechanics and Engineering}, year = {2014}, publisher = {Elsevier}, abstract = {Isogeometric analysis (IGA) is emerging as a technology bridging Computer Aided Geometric Design (CAGD), most commonly based on Non-Uniform Rational B-Splines (NURBS) surfaces, and engineering analysis. In finite element and boundary element isogeometric methods (FE-IGA and IGA-BEM), the NURBS basis functions that de- scribe the geometry define also the approximation spaces. In the FE-IGA approach, the surfaces generated by the CAGD tools need to be extended to volumetric descriptions, a major open problem in 3D. This additional passage can be avoided in principle when the partial differential equations to be solved admit a formulation in terms of bound- ary integral equations, leading to Boundary Element Isogeometric Analysis (IGA-BEM). The main advantages of such an approach are given by the dimensionality reduction of the problem (from volumetric-based to surface-based), by the fact that the interface with CAGD tools is direct, and by the possibility to treat exterior problems, where the computational domain is infinite. By contrast, these methods produce system matrices which are full, and require the integration of singular kernels. In this paper we address the second point and propose a nonsingular formulation of IGA-BEM for 3D Stokes flows, whose convergence is carefully tested numerically. Standard Gaussian quadrature rules suffice to integrate the boundary integral equations, and carefully chosen known exact solutions of the interior Stokes problem are used to correct the resulting matrices, extending the work by Klaseboer et al. [27] to IGA-BEM.}, keywords = {Isogeometric Analysis}, doi = {10.1016/j.cma.2013.09.017}, url = {http://hdl.handle.net/1963/6326}, author = {Luca Heltai and Marino Arroyo and Antonio DeSimone} } @conference {mola2014ship, title = {Potential Model for Ship Hydrodynamics Simulations Directly Interfaced with CAD Data Structures}, booktitle = {The 24th International Ocean and Polar Engineering Conference}, volume = {4}, year = {2014}, pages = {815{\textendash}822}, publisher = {International Society of Offshore and Polar Engineers}, organization = {International Society of Offshore and Polar Engineers}, author = {Andrea Mola and Luca Heltai and Antonio DeSimone and Massimiliano Berti} } @article {2014, title = {Quantum gauge symmetries in noncommutative geometry}, number = {Journal of Noncommutative Geometry;volume 8; issue 2; pages 433-471;}, year = {2014}, publisher = {European Mathematical Society Publishing House}, abstract = {We discuss generalizations of the notion of i) the group of unitary elements of a (real or complex) finite-dimensional C*-algebra, ii) gauge transformations and iii) (real) automorphisms in the framework of compact quantum group theory and spectral triples. The quantum analogue of these groups are defined as universal (initial) objects in some natural categories. After proving the existence of the universal objects, we discuss several examples that are of interest to physics, as they appear in the noncommutative geometry approach to particle physics: in particular, the C*-algebras M n(R), Mn(C) and Mn(H), describing the finite noncommutative space of the Einstein-Yang-Mills systems, and the algebras A F = C H M3 (C) and Aev = H H M4(C), that appear in Chamseddine-Connes derivation of the Standard Model of particle physics coupled to gravity. As a byproduct, we identify a "free" version of the symplectic group Sp.n/ (quaternionic unitary group).}, doi = {10.4171/JNCG/161}, url = {http://urania.sissa.it/xmlui/handle/1963/34897}, author = {Jyotishman Bhowmick and Francesco D{\textquoteright}Andrea and Biswarup Krishna Das and Ludwik Dabrowski} } @article {2014, title = {Quasi-static crack growth in hydraulic fracture}, journal = {Nonlinear Analysis}, volume = {109}, number = {Nonlinear Analysis, Theory, Methods and Applications;109}, year = {2014}, pages = {301-318}, publisher = {Elsevier}, type = {Journal article}, chapter = {301}, abstract = {We present a variational model for the quasi-static crack growth in hydraulic fracture in the framework of the energy formulation of rate-independent processes. The cracks are assumed to lie on a prescribed plane and to satisfy a very weak regularity assumption.

}, doi = {10.1016/j.na.2014.07.009}, url = {http://hdl.handle.net/20.500.11767/17350}, author = {Stefano Almi and Gianni Dal Maso and Rodica Toader} } @article {Maso2014, title = {Quasistatic Evolution in Perfect Plasticity as Limit of Dynamic Processes}, journal = {Journal of Dynamics and Differential Equations}, volume = {26}, number = {4}, year = {2014}, month = {Dec}, pages = {915{\textendash}954}, abstract = {We introduce a model of dynamic visco-elasto-plastic evolution in the linearly elastic regime and prove an existence and uniqueness result. Then we study the limit of (a rescaled version of) the solutions when the data vary slowly. We prove that they converge, up to a subsequence, to a quasistatic evolution in perfect plasticity.

}, issn = {1572-9222}, doi = {10.1007/s10884-014-9409-7}, url = {https://doi.org/10.1007/s10884-014-9409-7}, author = {Gianni Dal Maso and Riccardo Scala} } @article {doi:10.1142/S021820251450016X, title = {Quasistatic evolution models for thin plates arising as low energy Γ-limits of finite plasticity}, journal = {Mathematical Models and Methods in Applied Sciences}, volume = {24}, number = {10}, year = {2014}, pages = {2085-2153}, abstract = {In this paper we deduce by $\Gamma$-convergence some partially and fully linearized quasistatic evolution models for thin plates, in the framework of finite plasticity. Denoting by $\epsilon$ the thickness of the plate, we study the case where the scaling factor of the elasto-plastic energy is of order $\epsilon^{2 \alpha -2}$, with $\alpha\geq 3$. These scalings of the energy lead, in the absence of plastic dissipation, to the Von K{\'a}rm{\'a}n and linearized Von K{\'a}rm{\'a}n functionals for thin plates. We show that solutions to the three-dimensional quasistatic evolution problems converge, as the thickness of the plate tends to zero, to a quasistatic evolution associated to a suitable reduced model depending on $\alpha$.

}, doi = {10.1142/S021820251450016X}, url = {https://doi.org/10.1142/S021820251450016X}, author = {Elisa Davoli} } @article {2014, title = {A robotic crawler exploiting directional frictional interactions: experiments, numerics, and derivation of a reduced model}, journal = {Proceedings of the Royal Society A 470, 20140333 (2014)}, year = {2014}, publisher = {Royal Society Publishing}, abstract = {We present experimental and numerical results for a model crawler which is able to extract net positional changes from reciprocal shape changes, i.e. {\textquoteleft}breathing-like{\textquoteright} deformations, thanks to directional, frictional interactions with a textured solid substrate, mediated by flexible inclined feet. We also present a simple reduced model that captures the essential features of the kinematics and energetics of the gait, and compare its predictions with the results from experiments and from numerical simulations.}, doi = {10.1098/rspa.2014.0333}, author = {Giovanni Noselli and Antonio DeSimone} } @article {2014, title = {Second Order Asymptotic Development for the Anisotropic Cahn-Hilliard Functional}, year = {2014}, note = {This article is composed if 33 pages and recorded in PDF format}, publisher = {SISSA}, abstract = {The asymptotic behavior of an anisotropic Cahn-Hilliard functional with prescribed mass and Dirichlet boundary condition is studied when the parameter $\varepsilon$ that determines the width of the transition layers tends to zero. The double-well potential is assumed to be even and equal to $|s-1|^\beta$ near $s=1$, with $1<\beta<2$. The first order term in the asymptotic development by $\Gamma$-convergence is well-known, and is related to a suitable anisotropic perimeter of the interface. Here it is shown that, under these assumptions, the second order term is zero, which gives an estimate on the rate of convergence of the minimum values.}, keywords = {Gamma-convergence, Cahn-Hilliard functional, phase transitions}, url = {http://hdl.handle.net/1963/7390}, author = {Gianni Dal Maso and Irene Fonseca and Giovanni Leoni} } @article {2014, title = {Shape control of active surfaces inspired by the movement of euglenids}, number = {Journal of the Mechanics and Physics of Solids;volume 62; issue 1; pages 99-112;}, year = {2014}, publisher = {Elsevier}, abstract = {We examine a novel mechanism for active surface morphing inspired by the cell body deformations of euglenids. Actuation is accomplished through in-plane simple shear along prescribed slip lines decorating the surface. Under general non-uniform actuation, such local deformation produces Gaussian curvature, and therefore leads to shape changes. Geometrically, a deformation that realizes the prescribed local shear is an isometric embedding. We explore the possibilities and limitations of this bio-inspired shape morphing mechanism, by first characterizing isometric embeddings under axisymmetry, understanding the limits of embeddability, and studying in detail the accessibility of surfaces of zero and constant curvature. Modeling mechanically the active surface as a non-Euclidean plate (NEP), we further examine the mechanism beyond the geometric singularities arising from embeddability, where mechanics and buckling play a decisive role. We also propose a non-axisymmetric actuation strategy to accomplish large amplitude bending and twisting motions of elongated cylindrical surfaces. Besides helping understand how euglenids delicately control their shape, our results may provide the background to engineer soft machines.}, doi = {10.1016/j.jmps.2013.09.017}, url = {http://urania.sissa.it/xmlui/handle/1963/35118}, author = {Marino Arroyo and Antonio DeSimone} } @article {DANERI2014567, title = {Smooth approximation of bi-Lipschitz orientation-preserving homeomorphisms}, journal = {Annales de l{\textquoteright}Institut Henri Poincare (C) Non Linear Analysis}, volume = {31}, number = {3}, year = {2014}, pages = {567 - 589}, abstract = {We show that a planar bi-Lipschitz orientation-preserving homeomorphism can be approximated in the W1,p norm, together with its inverse, with an orientation-preserving homeomorphism which is piecewise affine or smooth.

}, issn = {0294-1449}, doi = {https://doi.org/10.1016/j.anihpc.2013.04.007}, url = {http://www.sciencedirect.com/science/article/pii/S0294144913000711}, author = {Sara Daneri and Aldo Pratelli} } @article {2014, title = {Some remarks on the seismic behaviour of embedded cantilevered retaining walls}, number = {Geotechnique;volume 64; issue 1; pages 40-50;}, year = {2014}, publisher = {Thomas Telford}, abstract = {This paper is a numerical investigation of the physical phenomena that control the dynamic behaviour of embedded cantilevered retaining walls. Recent experimental observations obtained from centrifuge tests have shown that embedded cantilevered retaining walls experience permanent displacements even before the acceleration reaches its critical value, corresponding to full mobilisation of the soil strength. The motivation for this work stems from the need to incorporate these observations in simplified design procedures. A parametric study was carried out on a pair of embedded cantilevered walls in dry sand, subjected to real earthquakes scaled at different values of the maximum acceleration. The results of these analyses indicate that, for the geotechnical design of the wall, the equivalent acceleration to be used in pseudo-static calculations can be related to the maximum displacement that the structure can sustain, and can be larger than the maximum acceleration expected at the site. For the structural design of the wall, it is suggested that the maximum bending moments of the wall can be computed using a realistic distribution of contact stress and a conservative value of the pseudo-static acceleration, taking into account two-dimensional amplification effects near the walls.}, doi = {10.1680/geot.13.P.031}, url = {http://urania.sissa.it/xmlui/handle/1963/35073}, author = {Riccardo Conti and F. Burali D{\textquoteright}Arezzo and Giulia M.B. Viggiani} } @article {2014, title = {Spontaneous division and motility in active nematic droplets}, number = {Physical review letters;volume 112; issue 14; article number 147802;}, year = {2014}, publisher = {American Physical Society}, abstract = {We investigate the mechanics of an active droplet endowed with internal nematic order and surrounded by an isotropic Newtonian fluid. Using numerical simulations we demonstrate that, due to the interplay between the active stresses and the defective geometry of the nematic director, this system exhibits two of the fundamental functions of living cells: spontaneous division and motility, by means of self-generated hydrodynamic flows. These behaviors can be selectively activated by controlling a single physical parameter, namely, an active variant of the capillary number.}, doi = {10.1103/PhysRevLett.112.147802}, url = {http://urania.sissa.it/xmlui/handle/1963/34902}, author = {Luca Giomi and Antonio DeSimone} } @article {2014, title = {Structure of classical (finite and affine) W-algebras}, number = {arXiv:1404.0715;}, year = {2014}, note = {40 pages}, institution = {SISSA}, abstract = {First, we derive an explicit formula for the Poisson bracket of the classical finite W-algebra W^{fin}(g,f), the algebra of polynomial functions on the Slodowy slice associated to a simple Lie algebra g and its nilpotent element f. On the other hand, we produce an explicit set of generators and we derive an explicit formula for the Poisson vertex algebra structure of the classical affine W-algebra W(g,f). As an immediate consequence, we obtain a Poisson algebra isomorphism between W^{fin}(g,f) and the Zhu algebra of W(g,f). We also study the generalized Miura map for classical W-algebras.}, url = {http://hdl.handle.net/1963/7314}, author = {Alberto De Sole and Victor G. Kac and Daniele Valeri} } @article {2013, title = {Analytical validation of a continuum model for epitaxial growth with elasticity on vicinal surfaces}, number = {Archive for Rational Mechanics and Analysis}, year = {2013}, publisher = {Springer}, abstract = {In this paper it is shown existence of weak solutions of a variational inequality derived from the continuum model introduced by Xiang [7, formula (3.62)] (see also the work of Xiang and E [8] and Xu and Xiang [9]) to describe the self-organization of terraces and steps driven by misfit elasticity between a film and a substrate in heteroepitaxial growth. This model is obtained as a continuum limit of discrete theories of Duport, Politi, and Villain [3] and Tersoff, Phang, Zhang, and Lagally[6].}, keywords = {singular nonlinear parabolic equations, Hilbert transform, thin films}, doi = {10.1007/s00205-014-0730-4}, url = {http://hdl.handle.net/1963/7245}, author = {Gianni Dal Maso and Irene Fonseca and Giovanni Leoni} } @article {2013, title = {Attainment results for nematic elastomers}, year = {2013}, institution = {SISSA}, abstract = {We consider a class of non-quasiconvex frame indifferent energy densities which includes Ogden-type energy densities for nematic elastomers. For the corresponding geometrically linear problem we provide an explicit minimizer of the energy functional satisfying a nontrivial boundary condition. Other attainment results, both for the nonlinear and the linearized model, are obtained by using the theory of convex integration introduced by Mueller and Sverak in the context of crystalline solids.}, url = {http://hdl.handle.net/1963/7174}, author = {Virginia Agostiniani and Gianni Dal Maso and Antonio DeSimone} } @article {2012, title = {Classical W-algebras and generalized Drinfeld-Sokolov bi-Hamiltonian systems within the theory of Poisson vertex algebras}, journal = {Communications in Mathematical Physics 323, nr. 2 (2013) 663-711}, number = {arXiv:1207.6286;}, year = {2013}, note = {43 pages. Second version with minor editing and corrections}, publisher = {Springer}, abstract = {We provide a description of the Drinfeld-Sokolov Hamiltonian reduction for the construction of classical W-algebras within the framework of Poisson vertex algebras. In this context, the gauge group action on the phase space is translated in terms of (the exponential of) a Lie conformal algebra action on the space of functions. Following the ideas of Drinfeld and Sokolov, we then establish under certain sufficient conditions the applicability of the Lenard-Magri scheme of integrability and the existence of the corresponding integrable hierarchy of bi-Hamiltonian equations.}, doi = {10.1007/s00220-013-1785-z}, url = {http://hdl.handle.net/1963/6978}, author = {Alberto De Sole and Victor G. Kac and Daniele Valeri} } @article {2013, title = {A combination between the reduced basis method and the ANOVA expansion: On the computation of sensitivity indices}, journal = {Comptes Rendus Mathematique. Volume 351, Issue 15-16, August 2013, Pages 593-598}, year = {2013}, publisher = {Elsevier}, abstract = {We consider a method to efficiently evaluate in a real-time context an output based on the numerical solution of a partial differential equation depending on a large number of parameters. We state a result allowing to improve the computational performance of a three-step RB-ANOVA-RB method. This is a combination of the reduced basis (RB) method and the analysis of variations (ANOVA) expansion, aiming at compressing the parameter space without affecting the accuracy of the output. The idea of this method is to compute a first (coarse) RB approximation of the output of interest involving all the parameter components, but with a large tolerance on the a posteriori error estimate; then, we evaluate the ANOVA expansion of the output and freeze the least important parameter components; finally, considering a restricted model involving just the retained parameter components, we compute a second (fine) RB approximation with a smaller tolerance on the a posteriori error estimate. The fine RB approximation entails lower computational costs than the coarse one, because of the reduction of parameter dimensionality. Our result provides a criterion to avoid the computation of those terms in the ANOVA expansion that are related to the interaction between parameters in the bilinear form, thus making the RB-ANOVA-RB procedure computationally more feasible.

}, keywords = {Partial differential equations}, doi = {10.1016/j.crma.2013.07.023}, url = {http://hdl.handle.net/1963/7389}, author = {Denis Devaud and Andrea Manzoni and Gianluigi Rozza} } @article {2013, title = {Common dynamical features of sensory adaptation in photoreceptors and olfactory sensory neurons.}, journal = {Nature. Scientific Reports 3, Article number: 1251, Published : 13 February 2013}, year = {2013}, publisher = {SISSA}, abstract = {Sensory systems adapt, i.e., they adjust their sensitivity to external stimuli according to the ambient level. In this paper we show that single cell electrophysiological responses of vertebrate olfactory receptors and of photoreceptors to different input protocols exhibit several common features related to adaptation, and that these features can be used to investigate the dynamical structure of the feedback regulation responsible for the adaptation. In particular, we point out that two different forms of adaptation can be observed, in response to steps and to pairs of pulses. These two forms of adaptation appear to be in a dynamical trade-off: the more adaptation to a step is close to perfect, the slower is the recovery in adaptation to pulse pairs and viceversa. Neither of the two forms is explained by the dynamical models currently used to describe adaptation, such as the integral feedback model.

}, doi = {10.1038/srep01251}, author = {Giovanna De Palo and Giuseppe Facchetti and Monica Mazzolini and Anna Menini and Vincent Torre and Claudio Altafini} } @article {DIPIERRO201330, title = {Concentration of solutions for a singularly perturbed mixed problem in non-smooth domains}, journal = {Journal of Differential Equations}, volume = {254}, number = {1}, year = {2013}, pages = {30 - 66}, abstract = {We consider a singularly perturbed problem with mixed Dirichlet and Neumann boundary conditions in a bounded domain $\Omega \subset \mathbb{R}^n$ whose boundary has an $(n-2)$-dimensional singularity. Assuming $1\<p\<\frac{n+2}{n-2}$, we prove that, under suitable geometric conditions on the boundary of the domain, there exist solutions which approach the intersection of the Neumann and the Dirichlet parts as the singular perturbation parameter tends to zero.

}, keywords = {Finite-dimensional reductions, Local inversion, Singularly perturbed elliptic problems}, issn = {0022-0396}, doi = {https://doi.org/10.1016/j.jde.2012.08.017}, url = {http://www.sciencedirect.com/science/article/pii/S0022039612003312}, author = {Serena Dipierro} } @article {2013, title = {Crawlers in viscous environments: linear vs nonlinear rheology}, journal = {International Journal of Non-Linear Mechanics 56, 142-147 (2013)}, year = {2013}, publisher = {Elsevier}, abstract = {We study model self-propelled crawlers which derive their propulsive capabilities from the tangential resistance to motion offered by the environment. Two types of relationships between tangential forces and slip velocities are considered: a linear, Newtonian one and a nonlinear one of Bingham-type. Different behaviors result from the two different rheologies. These differences and their implications in terms of motility performance are discussed. Our aim is to develop new tools and insight for future studies of cell motility by crawling.}, doi = {10.1016/j.ijnonlinmec.2013.02.007}, author = {Antonio DeSimone and Federica Guarnieri and Giovanni Noselli and Amabile Tatone} } @article {10978, title = {On critical behaviour in systems of Hamiltonian partial differential equations}, year = {2013}, institution = {SISSA}, abstract = {We study the critical behaviour of solutions to weakly dispersive Hamiltonian systems considered as perturbations of elliptic and hyperbolic systems of hydrodynamic type with two components. We argue that near the critical point of gradient catastrophe of the dispersionless system, the solutions to a suitable initial value problem for the perturbed equations are approximately described by particular solutions to the Painlev\'e-I (P$_I$) equation or its fourth order analogue P$_I^2$. As concrete examples we discuss nonlinear Schr\"odinger equations in the semiclassical limit. A numerical study of these cases provides strong evidence in support of the conjecture.

}, author = {Boris Dubrovin and Tamara Grava and Christian Klein and Antonio Moro} } @article {2013, title = {Curved noncommutative torus and Gauss--Bonnet}, journal = {Journal of Mathematical Physics. Volume 54, Issue 1, 22 January 2013, Article number 013518}, number = {arXiv:1204.0420v1;}, year = {2013}, note = {The article is composed of 13 pages and is recorded in PDF format}, publisher = {American Institute of Physics}, abstract = {We study perturbations of the flat geometry of the noncommutative two-dimensional torus T^2_\theta (with irrational \theta). They are described by spectral triples (A_\theta, \H, D), with the Dirac operator D, which is a differential operator with coefficients in the commutant of the (smooth) algebra A_\theta of T_\theta. We show, up to the second order in perturbation, that the zeta-function at 0 vanishes and so the Gauss-Bonnet theorem holds. We also calculate first two terms of the perturbative expansion of the corresponding local scalar curvature.}, keywords = {Geometry}, doi = {10.1063/1.4776202}, url = {http://hdl.handle.net/1963/7376}, author = {Ludwik Dabrowski and Andrzej Sitarz} } @article {2013, title = {Dirac operator on spinors and diffeomorphisms}, journal = {Classical and Quantum Gravity. Volume 30, Issue 1, 7 January 2013, Article number 015006}, number = {arXiv:1209.2021v1;}, year = {2013}, note = {This article is composed of 13 pages and is recorded in PDF format}, publisher = {IOP Publishing}, abstract = {The issue of general covariance of spinors and related objects is reconsidered. Given an oriented manifold $M$, to each spin structure $\sigma$ and Riemannian metric $g$ there is associated a space $S_{\sigma, g}$ of spinor fields on $M$ and a Hilbert space $\HH_{\sigma, g}= L^2(S_{\sigma, g},\vol{M}{g})$ of $L^2$-spinors of $S_{\sigma, g}$. The group $\diff{M}$ of orientation-preserving diffeomorphisms of $M$ acts both on $g$ (by pullback) and on $[\sigma]$ (by a suitably defined pullback $f^*\sigma$). Any $f\in \diff{M}$ lifts in exactly two ways to a unitary operator $U$ from $\HH_{\sigma, g} $ to $\HH_{f^*\sigma,f^*g}$. The canonically defined Dirac operator is shown to be equivariant with respect to the action of $U$, so in particular its spectrum is invariant under the diffeomorphisms.}, keywords = {gravity}, doi = {10.1088/0264-9381/30/1/015006}, url = {http://hdl.handle.net/1963/7377}, author = {Ludwik Dabrowski and Giacomo Dossena} } @article {2013, title = {Dislocation dynamics in crystals: a macroscopic theory in a fractional Laplace setting}, number = {SISSA preprint;43/2013/MATE}, year = {2013}, institution = {SISSA}, abstract = {We consider an evolution equation arising in the Peierls-Nabarro model for crystal dislocation. We study the evolution of such dislocation function and show that, at a macroscopic scale, the dislocations have the tendency to concentrate at single points of the crystal, where the size of the slip coincides with the natural periodicity of the medium. These dislocation points evolve according to the external stress and an interior repulsive potential.}, keywords = {nonlocal Allen-Cahn equation}, url = {http://hdl.handle.net/1963/7124}, author = {Serena Dipierro and Giampiero Palatucci and Enrico Valdinoci} } @article {2013, title = {Existence and symmetry results for a Schrodinger type problem involving the fractional Laplacian}, journal = {Le Matematiche (Catania), Vol. 68 (2013), no. 1: 201-216}, number = {arXiv:1202.0576v1;}, year = {2013}, publisher = {University of Catania}, abstract = {This paper deals with the following class of nonlocal Schr\"odinger equations $$ \displaystyle (-\Delta)^s u + u = |u|^{p-1}u \ \ \text{in} \ \mathbb{R}^N, \quad \text{for} \ s\in (0,1). $$ We prove existence and symmetry results for the solutions $u$ in the fractional Sobolev space $H^s(\mathbb{R}^N)$. Our results are in clear accordance with those for the classical local counterpart, that is when $s=1$.

}, author = {Serena Dipierro and Giampiero Palatucci and Enrico Valdinoci} } @article {2013, title = {Fracture models as Gamma-limits of damage models}, journal = {Communications on Pure and Applied Analysis 12 (2013) 1657-1686}, number = {SISSA;25/2011/M}, year = {2013}, publisher = {American Institute of Mathematical Sciences}, abstract = {We analyze the asymptotic behavior of a variational model for damaged elastic materials. This model depends on two small parameters, which govern the width of the damaged regions and the minimum elasticity constant attained in the damaged regions. When these parameters tend to zero, we find that the corresponding functionals Gamma-converge to a functional related to fracture mechanics. The corresponding problem is brittle or cohesive, depending on the asymptotic ratio of the two parameters.

}, doi = {10.3934/cpaa.2013.12.1657}, url = {http://hdl.handle.net/1963/4225}, author = {Gianni Dal Maso and Flaviana Iurlano} } @article {cacace_chambolle_desimone_fedeli_2013, title = {Macroscopic contact angle and liquid drops on rough solid surfaces via homogenization and numerical simulations}, journal = {ESAIM: Mathematical Modelling and Numerical Analysis}, volume = {47}, number = {3}, year = {2013}, pages = {837{\textendash}858}, publisher = {EDP Sciences}, doi = {10.1051/m2an/2012048}, author = {Cacace, S. and Antonin Chambolle and Antonio DeSimone and Livio Fedeli} } @article {2013, title = {Noncommutative circle bundles and new Dirac operators}, journal = {Communications in Mathematical Physics. Volume 318, Issue 1, 2013, Pages 111-130}, number = {arXiv:1012.3055v2;}, year = {2013}, note = {This article is composed of 25 pages and is recorded in PDF format}, publisher = {Springer}, abstract = {We study spectral triples over noncommutative principal U(1) bundles. Basing on the classical situation and the abstract algebraic approach, we propose an operatorial definition for a connection and compatibility between the connection and the Dirac operator on the total space and on the base space of the bundle. We analyze in details the example of the noncommutative three-torus viewed as a U(1) bundle over the noncommutative two-torus and find all connections compatible with an admissible Dirac operator. Conversely, we find a family of new Dirac operators on the noncommutative tori, which arise from the base-space Dirac operator and a suitable connection.}, keywords = {Quantum principal bundles}, doi = {10.1007/s00220-012-1550-8}, url = {http://hdl.handle.net/1963/7384}, author = {Ludwik Dabrowski and Andrzej Sitarz} } @article {2013, title = {One-dimensional swimmers in viscous fluids: dynamics, controllability, and existence of optimal controls}, number = {arXiv:1302.0901;}, year = {2013}, publisher = {SISSA}, abstract = {In this paper we study a mathematical model of one-dimensional swimmers performing a planar motion while fully immersed in a viscous fluid. The swimmers are assumed to be of small size, and all inertial effects are neglected. Hydrodynamic interactions are treated in a simplified way, using the local drag approximation of resistive force theory. We prove existence and uniqueness of the solution of the equations of motion driven by shape changes of the swimmer. Moreover, we prove a controllability result showing that given any pair of initial and final states, there exists a history of shape changes such that the resulting motion takes the swimmer from the initial to the final state. We give a constructive proof, based on the composition of elementary maneuvers (straightening and its inverse, rotation, translation), each of which represents the solution of an interesting motion planning problem. Finally, we prove the existence of solutions for the optimal control problem of finding, among the histories of shape changes taking the swimmer from an initial to a final state, the one of minimal energetic cost.

}, url = {http://hdl.handle.net/1963/6467}, author = {Gianni Dal Maso and Antonio DeSimone and Marco Morandotti} } @article {DAVOLI2013615, title = {A quasistatic evolution model for perfectly plastic plates derived by Γ-convergence}, journal = {Annales de l{\textquoteright}Institut Henri Poincare (C) Non Linear Analysis}, volume = {30}, number = {4}, year = {2013}, pages = {615 - 660}, abstract = {The subject of this paper is the rigorous derivation of a quasistatic evolution model for a linearly elastic{\textendash}perfectly plastic thin plate. As the thickness of the plate tends to zero, we prove via Γ-convergence techniques that solutions to the three-dimensional quasistatic evolution problem of Prandtl{\textendash}Reuss elastoplasticity converge to a quasistatic evolution of a suitable reduced model. In this limiting model the admissible displacements are of Kirchhoff{\textendash}Love type and the stretching and bending components of the stress are coupled through a plastic flow rule. Some equivalent formulations of the limiting problem in rate form are derived, together with some two-dimensional characterizations for suitable choices of the data.

}, keywords = {-convergence, Perfect plasticity, Prandtl{\textendash}Reuss plasticity, Quasistatic evolution, Rate-independent processes, Thin plates}, issn = {0294-1449}, doi = {https://doi.org/10.1016/j.anihpc.2012.11.001}, url = {http://www.sciencedirect.com/science/article/pii/S0294144912001035}, author = {Elisa Davoli and Maria Giovanna Mora} } @inbook {2015, title = {Reduced Basis Approximation for the Structural-Acoustic Design based on Energy Finite Element Analysis (RB-EFEA)}, booktitle = {CEMRACS 2013 - Modelling and simulation of complex systems: stochastic and deterministic approaches}, volume = {48}, number = {ESAIM Proceedings}, year = {2013}, pages = {98-115}, doi = { http://dx.doi.org/10.1051/proc/201448004}, author = {Denis Devaud and Gianluigi Rozza} } @article {2012, title = {A stable and adaptive semi-Lagrangian potential model for unsteady and nonlinear ship-wave interactions}, journal = {Engineering Analysis with Boundary Elements, 37(1):128 {\textendash} 143, 2013.}, number = {SISSA;06/2012/M}, year = {2013}, publisher = {SISSA}, abstract = {We present an innovative numerical discretization of the equations of inviscid potential flow for the simulation of three dimensional unsteady and nonlinear water waves generated by a ship hull advancing in water. The equations of motion are written in a semi-Lagrangian framework, and the resulting integro-diff erential equations are discretized in space via an adaptive iso-parametric collocation Boundary Element Method, and in time via adaptive implicit Backward Di erentiation Formulas (BDF) with variable step and variable order. When the velocity of the advancing ship hull is non-negligible, the semi-Lagrangian formulation (also known as Arbitrary Lagrangian Eulerian formulation, or ALE) of the free surface equations contains dominant transport terms which are stabilized with a Streamwise Upwind Petrov-Galerkin (SUPG) method. The SUPG stabilization allows automatic and robust adaptation of the spatial discretization with unstructured quadrilateral grids. Preliminary results are presented where we compare our numerical model with experimental results on the case of a Wigley hull advancing in calm water with fi xed sink and trim.

}, keywords = {Unsteady ship-wave interaction}, url = {http://hdl.handle.net/1963/5669}, author = {Andrea Mola and Luca Heltai and Antonio DeSimone} } @article {2013, title = {On Sudakov{\textquoteright}s type decomposition of transference plans with norm costs}, number = {SISSA;51/2013/MATE}, year = {2013}, institution = {SISSA}, url = {http://hdl.handle.net/1963/7206}, author = {Stefano Bianchini and Sara Daneri} } @article {2012, title = {Asymptotics of the s-perimeter as s {\textrightarrow}0 }, journal = {Discrete Contin. Dyn. Syst. 33, nr.7 (2012): 2777-2790}, number = {arXiv:1204.0750v2;}, year = {2012}, publisher = {American Institute of Mathematical Sciences}, abstract = {We deal with the asymptotic behavior of the $s$-perimeter of a set $E$ inside a domain $\Omega$ as $s\searrow0$. We prove necessary and sufficient conditions for the existence of such limit, by also providing an explicit formulation in terms of the Lebesgue measure of $E$ and $\Omega$. Moreover, we construct examples of sets for which the limit does not exist.

}, doi = {10.3934/dcds.2013.33.2777}, author = {Serena Dipierro and Alessio Figalli and Giampiero Palatucci and Enrico Valdinoci} } @article {2012, title = {Classical double, R-operators, and negative flows of integrable hierarchies}, journal = {Theoretical and Mathematical Physics. Volume 172, Issue 1, July 2012, Pages 911-931}, year = {2012}, publisher = {SISSA}, abstract = {Using the classical double G of a Lie algebra g equipped with the classical R-operator, we define two sets of functions commuting with respect to the initial Lie{\textendash}Poisson bracket on g and its extensions. We consider examples of Lie algebras g with the {\textquotedblleft}Adler{\textendash}Kostant{\textendash}Symes{\textquotedblright} R-operators and the two corresponding sets of mutually commuting functions in detail. Using the constructed commutative Hamiltonian flows on different extensions of g, we obtain zero-curvature equations with g-valued U{\textendash}V pairs. The so-called negative flows of soliton hierarchies are among such equations. We illustrate the proposed approach with examples of two-dimensional Abelian and non-Abelian Toda field equations.}, doi = {10.1007/s11232-012-0086-6}, url = {http://hdl.handle.net/1963/6468}, author = {Boris Dubrovin and Taras V. Skrypnyk} } @inbook {9897, title = {Computing optimal strokes for low reynolds number swimmers}, booktitle = {Natural locomotion in fluids and on surfaces : swimming, flying, and sliding / editors Stephen Childress, Anette Hosoi, William W. Schultz, and Z. Jane Wang, editors,}, number = {The IMA volumes in mathematics and its applications;155}, year = {2012}, publisher = {Springer}, organization = {Springer}, abstract = {We discuss connections between low-Reynolds-number swimming and geometric control theory, and present a general algorithm for the numerical computation of energetically optimal strokes. As an illustration of our approach, we show computed motility maps and optimal strokes for two model swimmers.

}, keywords = {Numerical analysis.}, isbn = {9781461439967}, doi = {10.1007/978-1-4614-3997-4_13}, url = {http://hdl.handle.net/1963/6445}, author = {Antonio DeSimone and Luca Heltai and Fran{\c c}ois Alouges and Lefebvre-Lepot Aline} } @article {bonheure2012concentration, title = {Concentration on circles for nonlinear Schr{\"o}dinger{\textendash}Poisson systems with unbounded potentials vanishing at infinity}, journal = {Communications in Contemporary Mathematics}, volume = {14}, number = {02}, year = {2012}, pages = {1250009}, publisher = {World Scientific}, abstract = {The present paper is devoted to weighted nonlinear Schr{\"o}dinger{\textendash}Poisson systems with potentials possibly unbounded and vanishing at infinity. Using a purely variational approach, we prove the existence of solutions concentrating on a circle.

}, doi = {10.1142/S0219199712500095}, url = {https://doi.org/10.1142/S0219199712500095}, author = {Bonheure, Denis and Di Cosmo, Jonathan and Mercuri, Carlo} } @article {2012, title = {Crawling motility through the analysis of model locomotors: two case studies}, journal = {The European Physical Journal E, Volume 35, Issue 9, September 2012, Article number85}, number = {PMID:22972227;}, year = {2012}, publisher = {Springer}, abstract = {We study model locomotors on a substrate, which derive their propulsive capabilities from the tangential (viscous or frictional) resistance offered by the substrate. Our aim is to develop new tools and insight for future studies of cellular motility by crawling and of collective bacterial motion. The purely viscous case (worm) is relevant for cellular motility by crawling of individual cells. We re-examine some recent results on snail locomotion in order to assess the role of finely regulated adhesion mechanisms in crawling motility. Our main conclusion is that such regulation, although well documented in several biological systems, is not indispensable to accomplish locomotion driven by internal deformations, provided that the crawler may execute sufficiently large body deformations. Thus, there is no snail theorem. Namely, the crawling analog of the scallop theorem of low Reynolds number hydrodynamics does not hold for snail-like crawlers. The frictional case is obtained by assuming that the viscous coefficient governing tangential resistance forces, which act parallel and in the direction opposite to the velocity of the point to which they are applied, depends on the normal force acting at that point. We combine these surface interactions with inertial effects in order to investigate the mechanisms governing the motility of a bristle-robot. This model locomotor is easily manufactured and has been proposed as an effective tool to replicate and study collective bacterial motility.}, doi = {10.1140/epje/i2012-12085-x}, url = {http://hdl.handle.net/1963/7017}, author = {Antonio DeSimone and Amabile Tatone} } @article {2012, title = {On the critical behavior in nonlinear evolutionary PDEs with small viscocity}, journal = {Russian Journal of Mathematical Physics. Volume 19, Issue 4, December 2012, Pages 449-460}, year = {2012}, publisher = {SISSA}, abstract = {We address the problem of general dissipative regularization of the quasilinear transport equation. We argue that the local behavior of solutions to the regularized equation near the point of gradient catastrophe for the transport equation is described by the logarithmic derivative of the Pearcey function, a statement generalizing the result of A.M.Il\\\'in \\\\cite{ilin}. We provide some analytic arguments supporting such conjecture and test it numerically.}, doi = {10.1134/S106192081204005X}, url = {http://hdl.handle.net/1963/6465}, author = {Boris Dubrovin and Maria Elaeva} } @article {2012, title = {A dynamical feedback model for adaptation in the olfactory transduction pathway}, journal = {Biophysical Journal. Volume 102, Issue 12, 20 June 2012, Pages 2677-2686}, number = {PMID:22735517;}, year = {2012}, publisher = {Biophysical Society, Elsevier}, abstract = {Olfactory transduction exhibits two distinct types of adaptation, which we denote multipulse and step adaptation. In terms of measured transduction current, multipulse adaptation appears as a decrease in the amplitude of the second of two consecutive responses when the olfactory neuron is stimulated with two brief pulses. Step adaptation occurs in response to a sustained steplike stimulation and is characterized by a return to a steady-state current amplitude close to the prestimulus value, after a transient peak. In this article, we formulate a dynamical model of the olfactory transduction pathway, which includes the kinetics of the CNG channels, the concentration of Ca ions flowing through them, and the Ca-complexes responsible for the regulation. Based on this model, a common dynamical explanation for the two types of adaptation is suggested. We show that both forms of adaptation can be well described using different time constants for the kinetics of Ca ions (faster) and the kinetics of the feedback mechanisms (slower). The model is validated on experimental data collected in voltage-clamp conditions using different techniques and animal species.}, doi = {10.1016/j.bpj.2012.04.040}, url = {http://hdl.handle.net/1963/7019}, author = {Giovanna De Palo and Anna Boccaccio and Andrew Miri and Anna Menini and Claudio Altafini} } @article {2012, title = {Gamma-convergence and H-convergence of linear elliptic operators}, journal = {Journal de Math{\'e}matiques Pures et Appliqu{\'e}es, Available online 12 September 2012}, number = {SISSA;04/2012/M}, year = {2012}, publisher = {Elsevier}, keywords = {Linear elliptic operators}, doi = {10.1016/j.matpur.2012.09.004}, url = {http://hdl.handle.net/1963/5878}, author = {Nadia Ansini and Gianni Dal Maso and Caterina Ida Zeppieri} } @article {2012, title = {On the genus two free energies for semisimple Frobenius manifolds}, journal = {Russian Journal of Mathematical Physics. Volume 19, Issue 3, September 2012, Pages 273-298}, number = {arXiv:1205.5990;}, year = {2012}, note = {36 pages, 3 figures}, publisher = {SISSA}, abstract = {We represent the genus two free energy of an arbitrary semisimple Frobenius\\r\\nmanifold as a sum of contributions associated with dual graphs of certain\\r\\nstable algebraic curves of genus two plus the so-called \\\"genus two G-function\\\".\\r\\nConjecturally the genus two G-function vanishes for a series of important\\r\\nexamples of Frobenius manifolds associated with simple singularities as well as\\r\\nfor ${\\\\bf P}^1$-orbifolds with positive Euler characteristics. We explain the\\r\\nreasons for such Conjecture and prove it in certain particular cases.}, doi = {10.1134/S1061920812030028}, url = {http://hdl.handle.net/1963/6464}, author = {Boris Dubrovin and Si-Qi Liu and Youjin Zhang} } @article {2012, title = {Hybridization in nanostructured DNA monolayers probed by AFM: theory versus experiment}, journal = {Nanoscale. 2012 Mar; 4(5):1734-41}, number = {PMID:22301788;}, year = {2012}, publisher = {Royal Society of Chemistry}, abstract = {Nanografted monolayers (NAMs) of DNA show novel physico-chemical properties that make them ideally suited for advanced biosensing applications. In comparison with alternative solid-phase techniques for diagnostic DNA detection, NAMs have the advantage of combining a small size with a high homogeneity of the DNA surface coverage. These two properties favour the extreme miniaturization and ultrasensitivity in high-throughput biosensing devices. The systematic use of NAMs for quantitative DNA (and protein) detection has so far suffered from the lack of a control on key fabrication parameters, such as the ss- or ds-DNA surface coverage. Here we report on a combined experimental-computational study that allows us to estimate the surface density of the grafted DNA by analyzing the sample mechanical response, that is the DNA patch height vs. applied tip load curves. It is shown that the same analysis scheme can be used to detect the occurrence of hybridization with complementary strands in solution and estimate its efficiency. Thanks to these quantitative relationships it is possible to use a single AFM-based setup to: (i) fabricate a DNA NAM, (ii) control the DNA surface coverage, and (iii) characterize its level of hybridization helping the design of NAMs with pre-determined fabrication parameters.}, doi = {10.1039/c2nr11662f}, author = {Alessandro Bosco and Fouzia Bano and Pietro Parisse and Loredana Casalis and Antonio DeSimone and Cristian Micheletti} } @article {2012, title = {Linear elasticity obtained from finite elasticity by Gamma-convergence under weak coerciveness conditions}, journal = {Ann. Inst. H. Poincare Anal. Non Lineaire}, volume = {29}, number = {SISSA;30/2011/M}, year = {2012}, pages = {715-735}, publisher = {Gauthier-Villars;Elsevier}, abstract = {The energy functional of linear elasticity is obtained as G-limit of suitable rescalings of the energies of finite elasticity...

}, keywords = {Nonlinear elasticity}, doi = {10.1016/j.anihpc.2012.04.001}, url = {http://hdl.handle.net/1963/4267}, author = {Virginia Agostiniani and Gianni Dal Maso and Antonio DeSimone} } @proceedings {2012, title = {Mathematical and numerical modeling of liquid crystal elastomer phase transition and deformation}, year = {2012}, publisher = {Cambridge University Press}, abstract = {Liquid crystal (in particular, nematic) elastomers consist of cross-linked flexible polymer chains with embedded stiff rod molecules that allow them to behave as a rubber and a liquid crystal. Nematic elastomers are characterized by a phase transition from isotropic to nematic past a temperature threshold. They behave as rubber at high temperature and show nematic behavior below the temperature threshold. Such transition is reversible. While in the nematic phase, the rod molecules are aligned along the direction of the "nematic director". This molecular rearrangement induces a stretch in the polymer chains and hence macroscopic spontaneous deformations. The coupling between nematic order parameter and deformation gives rise to interesting phenomena with a potential for new interesting applications. In the biological field, the ability to considerably change their length makes them very promising as artificial muscles actuators. Their tunable optical properties make them suitable, for example, as lenses for new imaging systems. We present a mathematical model able to describe the behavior of nematic elastomers and numerical simulations reproducing such peculiar behavior. We use a geometrically linear version of the Warner and Terentjev model [1] and consider cooling experiments and stretching experiments in the direction perpendicular to the one of the director at cross-linking.}, keywords = {Artificial muscle}, isbn = {9781605113807}, doi = {10.1557/opl.2012.249}, url = {http://hdl.handle.net/1963/7020}, author = {Mariarita De Luca and Antonio DeSimone} } @article {2012, title = {Numerical modelling of installation effects for diaphragm walls in sand}, journal = {Acta Geotechnica, Volume 7, Issue 3, September 2012, Pages 219-237}, year = {2012}, publisher = {Springer}, abstract = {The scopes of this work are to study the mechanisms of load transfer and the deformations of the ground during slurry trenching and concreting in dry sand and to evaluate their effects on service structural loads, wall deflections and ground displacements behind the wall caused by subsequent excavation. A series of three-dimensional finite element analyses was carried out modelling the installation of diaphragm walls consisting of panels of different length. The soil was modelled as either linearly elastic-perfectly plastic or incrementally non-linear (hypoplastic) with elastic strain range. Plane strain analyses of diaphragm walls of identical cross section were also carried out in which wall installation was either modelled or the wall was wished in place (WIP). The analyses predict ground movements consistent with the experimental observations both in magnitude and trend. The results also show that the maximum horizontal wall deflections and structural loads reduce with increasing panel aspect ratio towards a minimum which is about twice the value computed for WIP analyses. Panel aspect ratios should be larger than about three to take advantage of the three-dimensional effects. The pattern and magnitude of surface vertical displacements obtained from linearly elastic-perfectly plastic analyses, no matter whether three- or two-dimensional, are unrealistic.}, keywords = {Constitutive relations}, doi = {10.1007/s11440-011-0157-0}, url = {http://hdl.handle.net/1963/6934}, author = {Riccardo Conti and Luca de Sanctis and Giulia M.B. Viggiani} } @article {2012, title = {Ogden-type energies for nematic elastomers}, journal = {International Journal of Non-Linear mechanics }, volume = {47}, year = {2012}, pages = {402-412}, publisher = {Elsevier}, abstract = {Ogden-type extensions of the free-energy densities currently used to model the mechanical behavior of nematic elastomers are proposed and analyzed. Based on a multiplicative decomposition of the deformation gradient into an elastic and a spontaneous or remanent part, they provide a suitable framework to study the stiffening response at high imposed stretches. Geometrically linear versions of the models (Taylor expansions at order two) are provided and discussed. These small strain theories provide a clear illustration of the geometric structure of the underlying energy landscape (the energy grows quadratically with the distance from a non-convex set of spontaneous strains or energy wells). The comparison between small strain and finite deformation theories may also be useful in the opposite direction, inspiring finite deformation generalizations of small strain theories currently used in the mechanics of active and phase-transforming materials. The energy well structure makes the free-energy densities non-convex. Explicit quasi-convex envelopes are provided, and applied to compute the stiffening response of a specimen tested in plane strain extension experiments (pure shear).

}, keywords = {Nonlinear elasticity}, doi = {10.1016/j.ijnonlinmec.2011.10.001}, author = {Virginia Agostiniani and Antonio DeSimone} } @article {2012, title = {Quasistatic evolution for Cam-Clay plasticity: properties of the viscosity solution}, journal = {Calculus of variations and partial differential equations 44 (2012) 495-541}, number = {SISSA;46/2010/M}, year = {2012}, publisher = {Springer}, abstract = {Cam-Clay plasticity is a well established model for the description of the mechanics of fine grained soils. As solutions can develop discontinuities in time, a weak notion of solution, in terms of a rescaled time s , has been proposed in [8] to give a meaning to this discontinuous evolution. In this paper we first prove that this rescaled evolution satisfies the flow-rule for the rate of plastic strain, in a suitable measure-theoretical sense. In the second part of the paper we consider the behavior of the evolution in terms of the original time variable t . We prove that the unrescaled solution satisfies an energy-dissipation balance and an evolution law for the internal variable, which can be expressed in terms of integrals depending only on the original time. Both these integral identities contain terms concentrated on the jump times, whose size can only be determined by looking at the rescaled formulation.

}, doi = {10.1007/s00526-011-0443-6}, url = {http://hdl.handle.net/1963/3900}, author = {Gianni Dal Maso and Antonio DeSimone and Francesco Solombrino} } @article {2012, title = {Reverse engineering the euglenoid movement}, journal = {Proceedings of the National Academy of Sciences of the United States of America. Volume 109, Issue 44, 30 October 2012, Pages 17874-17879}, year = {2012}, abstract = {Euglenids exhibit an unconventional motility strategy amongst unicellular eukaryotes, consisting of large-amplitude highly concerted deformations of the entire body (euglenoid movement or metaboly). A plastic cell envelope called pellicle mediates these deformations. Unlike ciliary or flagellar motility, the biophysics of this mode is not well understood, including its efficiency and molecular machinery. We quantitatively examine video recordings of four euglenids executing such motions with statistical learning methods. This analysis reveals strokes of high uniformity in shape and pace. We then interpret the observations in the light of a theory for the pellicle kinematics, providing a precise understanding of the link between local actuation by pellicle shear and shape control. We systematically understand common observations, such as the helical conformations of the pellicle, and identify previously unnoticed features of metaboly. While two of our euglenids execute their stroke at constant body volume, the other two exhibit deviations of about 20\% from their average volume, challenging current models of low Reynolds number locomotion. We find that the active pellicle shear deformations causing shape changes can reach 340\%, and estimate the velocity of the molecular motors. Moreover, we find that metaboly accomplishes locomotion at hydrodynamic efficiencies comparable to those of ciliates and flagellates. Our results suggest new quantitative experiments, provide insight into the evolutionary history of euglenids, and suggest that the pellicle may serve as a model for engineered active surfaces with applications in microfluidics.}, keywords = {microswimmers}, doi = {10.1073/pnas.1213977109}, url = {http://hdl.handle.net/1963/6444}, author = {Marino Arroyo and Luca Heltai and Daniel Mill{\'a}n and Antonio DeSimone} } @mastersthesis {2012, title = {Some aspects of spinors {\textendash} classical and noncommutative}, year = {2012}, school = {SISSA}, url = {http://hdl.handle.net/1963/6317}, author = {Giacomo Dossena} } @article {2012, title = {Some remarks on quantum mechanics}, journal = {International Journal of Geometric Methods in Modern Physics, Volume 9, Issue 2, March 2012, Article number1260018}, year = {2012}, publisher = {World Scientific Publishing}, abstract = {We discuss the similarities and differences between the formalism of Hamiltonian Classical Mechanics and of Quantum Mechanics and exemplify the differences through an analysis of tracks in a cloud chamber.}, keywords = {Quantum mechanics}, doi = {10.1142/S0219887812600183}, url = {http://hdl.handle.net/1963/7018}, author = {Gianfausto Dell{\textquoteright}Antonio} } @article {2012, title = {Stability for a System of N Fermions Plus a Different Particle with Zero-Range Interactions}, journal = {Rev. Math. Phys. 24 (2012), 1250017}, number = {arXiv:1201.5740;}, year = {2012}, publisher = {World Scientific}, abstract = {We study the stability problem for a non-relativistic quantum system in\\r\\ndimension three composed by $ N \\\\geq 2 $ identical fermions, with unit mass,\\r\\ninteracting with a different particle, with mass $ m $, via a zero-range\\r\\ninteraction of strength $ \\\\alpha \\\\in \\\\R $. We construct the corresponding\\r\\nrenormalised quadratic (or energy) form $ \\\\form $ and the so-called\\r\\nSkornyakov-Ter-Martirosyan symmetric extension $ H_{\\\\alpha} $, which is the\\r\\nnatural candidate as Hamiltonian of the system. We find a value of the mass $\\r\\nm^*(N) $ such that for $ m > m^*(N)$ the form $ \\\\form $ is closed and bounded from below. As a consequence, $ \\\\form $ defines a unique self-adjoint and bounded from below extension of $ H_{\\\\alpha}$ and therefore the system is stable. On the other hand, we also show that the form $ \\\\form $ is unbounded from below for $ m < m^*(2)$. In analogy with the well-known bosonic case, this suggests that the system is unstable for $ m < m^*(2)$ and the so-called Thomas effect occurs.}, doi = {10.1142/S0129055X12500171}, url = {http://hdl.handle.net/1963/6069}, author = {Michele Correggi and Gianfausto Dell{\textquoteright}Antonio and Domenico Finco and Alessandro Michelangeli and Alessandro Teta} } @conference {Mola2012, title = {A stable semi-lagrangian potential method for the simulation of ship interaction with unsteady and nonlinear waves}, booktitle = {17th Int. Conf. Ships Shipp. Res.}, year = {2012}, author = {Andrea Mola and Luca Heltai and Antonio DeSimone} } @article {2012, title = {Thermodynamic phase transitions and shock singularities}, journal = {Proc. R. Soc. A 8 March 2012 vol. 468 no. 2139 701-719}, number = {arXiv:1107.0394;}, year = {2012}, publisher = {The Royal Society}, abstract = {We show that under rather general assumptions on the form of the entropy\\r\\nfunction, the energy balance equation for a system in thermodynamic equilibrium is equivalent to a set of nonlinear equations of hydrodynamic type. This set of equations is integrable via the method of the characteristics and it provides the equation of state for the gas. The shock wave catastrophe set identifies the phase transition. A family of explicitly solvable models of\\r\\nnon-hydrodynamic type such as the classical plasma and the ideal Bose gas are\\r\\nalso discussed.}, doi = {10.1098/rspa.2011.0459}, url = {http://hdl.handle.net/1963/6090}, author = {Giuseppe De Nittis and Antonio Moro} } @article {2011, title = {Adaptation as a genome-wide autoregulatory principle in the stress response of yeast.}, journal = {IET systems biology. 2011 Jul; 5(4):269-79}, number = {PMID:21823758;}, year = {2011}, publisher = {The Institution of Engineering and Technology}, abstract = {The gene expression response of yeast to various types of stresses/perturbations shows a common functional and dynamical pattern for the vast majority of genes, characterised by a quick transient peak (affecting primarily short genes) followed by a return to the pre-stimulus level. Kinetically, this process of adaptation following the transient excursion can be modelled using a genome-wide autoregulatory mechanism by means of which yeast aims at maintaining a preferential concentration in its mRNA levels. The resulting feedback system explains well the different time constants observable in the transient response, while being in agreement with all the known experimental dynamical features. For example, it suggests that a very rapid transient can be induced also by a slowly varying concentration of the gene products.}, doi = {10.1049/iet-syb.2009.0050}, url = {http://hdl.handle.net/1963/5106}, author = {F Eduati and B Di Camillo and G Toffolo and Claudio Altafini and Giovanna De Palo and Mattia Zampieri} } @article {AIHPC_2011__28_1_107_0, title = {Concentration of solutions for a singularly perturbed Neumann problem in non-smooth domains}, journal = {Annales de l{\textquoteright}I.H.P. Analyse non lin{\'e}aire}, volume = {28}, number = {1}, year = {2011}, pages = {107-126}, publisher = {Elsevier}, doi = {10.1016/j.anihpc.2010.11.003}, url = {http://www.numdam.org/item/AIHPC_2011__28_1_107_0}, author = {Serena Dipierro} } @article {10654, title = {Cones of divisors of blow-ups of projective spaces}, journal = {Le Matematiche (Catania), volume 66, Issue no.2, (2011), pages : 153-187}, year = {2011}, publisher = {Universit{\`a} degli Studi di Catania. Dipartimento di matematica}, abstract = {We investigate Mori dream spaces obtained by blowing-up the n-dimensional complex projective space at n+1, n+2 or n+3 points in very general position. Using toric techniques we study the movable cone of the blow-up of Pn at n+1 points, its decomposition into nef chambers and the action of theWeyl group on the set of chambers. Moreover, using different methods, we explicitly write down the equations of the movable cone also for Pn blown-up at n+2 points.}, keywords = {Mori dream space}, doi = {10.4418/2011.66.2.13}, url = {http://hdl.handle.net/1963/6613}, author = {Alessio Lo Giudice and Salvatore Cacciola and M. Donten-Bury and O. Dumitrescu and J. Park} } @article {2011, title = {Crack growth with non-interpenetration : a simplified proof for the pure Neumann problem}, journal = {Discrete and Continuous Dynamical Systems - Series A 31 (2011) 1219-1231}, number = {SISSA;70/2009/M}, year = {2011}, publisher = {American Institute of Mathematical Sciences}, abstract = {We present a recent existence result concerning the quasi-static evolution of cracks in hyperelastic brittle materials, in the frame-work of finite elasticity with non-interpenetration. In particular, here we consider the problem where no Dirichlet conditions are imposed, the boundary is traction-free, and the body is subject only to time-dependent volume forces. This allows us to present the main ideas of the proof in a simpler way, avoiding some of the technicalities needed in the general case, studied in.}, doi = {10.3934/dcds.2011.31.1219}, url = {http://hdl.handle.net/1963/3801}, author = {Gianni Dal Maso and Giuliano Lazzaroni} } @article {2011, title = {Critical points of the Moser-Trudinger functional}, number = {SISSA;46/2011/M}, year = {2011}, institution = {SISSA}, keywords = {Moser-Trudinger inequality}, url = {http://hdl.handle.net/1963/4592}, author = {Francesca De Marchis and Andrea Malchiodi and Luca Martinazzi} } @article {2011, title = {Cytoskeletal actin networks in motile cells are critically self-organized systems synchronized by mechanical interactions}, journal = {PNAS 108 (2011) 13978}, year = {2011}, publisher = {National Academy of Sciences}, doi = {10.1073/pnas.1100549108}, url = {http://hdl.handle.net/1963/4358}, author = {Luca Cardamone and Alessandro Laio and Rajesh Shahapure and Antonio DeSimone} } @article {2011, title = {D-branes, surface operators, and ADHM quiver representations}, number = {SISSA;01/2011/FM}, year = {2011}, note = {45 pages, v2: minor corrections}, institution = {SISSA}, abstract = {A supersymmetric quantum mechanical model is constructed for BPS states bound to surface operators in five dimensional SU(r) gauge theories using D-brane engineering. This model represents the effective action of a certain D2-brane configuration, and is naturally obtained by dimensional reduction of a quiver $(0,2)$ gauged linear sigma model. In a special stability chamber, the resulting moduli space of quiver representations is shown to be smooth and isomorphic to a moduli space of framed quotients on the projective plane. A precise conjecture relating a K-theoretic partition function of this moduli space to refined open string invariants of toric lagrangian branes is formulated for conifold and local P^1 x P^1 geometries.}, url = {http://hdl.handle.net/1963/4133}, author = {Ugo Bruzzo and Duiliu-Emanuel Diaconescu and M. Yardim and G. Pan and Yi Zhang and Chuang Wu-yen} } @mastersthesis {2011, title = {Dimensional Reduction and Approximation of Measures and Weakly Differentiable Homeomorphisms}, year = {2011}, school = {SISSA}, abstract = {This thesis is devoted to the study of two different problems: the properties of the disintegration of the Lebesgue measure on the faces of a convex function and the existence of smooth approximations of bi-Lipschitz orientation-preserving homeomorphisms in the plane.}, url = {http://hdl.handle.net/1963/5348}, author = {Sara Daneri} } @article {2011, title = {Ennio De Giorgi and Γ-convergence}, journal = {Discrete and Continuous Dynamical Systems - Series A 31 (2011) 1017-1021}, year = {2011}, publisher = {American Institute of Mathematical Sciences}, abstract = {Γ-convergence was introduced by Ennio De Giorgi in a series of papers published between 1975 and 1983. In the same years he developed many applications of this tool to a great variety of asymptotic problems in the calculus of variations and in the theory of partial differential equations.}, doi = {10.3934/dcds.2011.31.1017}, url = {http://hdl.handle.net/1963/5308}, author = {Gianni Dal Maso} } @article {2011, title = {An Existence and Uniqueness Result for the Motion of Self-Propelled Microswimmers}, journal = {SIAM J. Math. Anal.}, volume = { 43}, number = {SISSA;44/2010/M}, year = {2011}, pages = {1345-1368}, publisher = {Society for Industrial and Applied Mathematics}, abstract = {We present an analytical framework to study the motion of micro-swimmers in a viscous fluid. Our main result is that, under very mild regularity assumptions, the change of shape determines uniquely the motion of the swimmer. We assume that the Reynolds number is very small, so that the velocity field of the surrounding, infinite fluid is governed by the Stokes system and all inertial effects can be neglected. Moreover, we enforce the self propulsion constraint (no external forces and torques). Therefore, Newton\\\'s equations of motion reduce to the vanishing of the viscous drag force and torque acting on the body. By exploiting an integral representation of viscous force and torque, the equations of motion can be reduced to a system of six ordinary differential equations. Variational techniques are used to prove the boundedness and measurability of its coefficients, so that classical results on ordinary differential equations can be invoked to prove existence and uniqueness of the solution.

}, doi = {10.1137/10080083X}, url = {http://hdl.handle.net/1963/3894}, author = {Gianni Dal Maso and Antonio DeSimone and Marco Morandotti} } @article {2011, title = {Existence for wave equations on domains with arbitrary growing cracks}, journal = {Rend. Lincei Mat. Appl. 22 (2011) 387-408}, number = {SISSA;32/2011/M}, year = {2011}, publisher = {European Mathematical Society}, abstract = {In this paper we formulate and study scalar wave equations on domains with arbitrary growing cracks. This includes a zero Neumann condition on the crack sets, and the only assumptions on these sets are that they have bounded surface measure and are growing in the sense of set inclusion. In particular, they may be dense, so the weak formulations must fall outside of the usual weak formulations using Sobolev spaces. We study both damped and undamped equations, showing existence and, for the damped equation, uniqueness and energy conservation.}, keywords = {Wave equation}, doi = {10.4171/RLM/606}, url = {http://hdl.handle.net/1963/4284}, author = {Gianni Dal Maso and Cristopher J. Larsen} } @article {2011, title = {Gamma-convergence of energies for nematic elastomers in the small strain limit}, journal = {Continuum. Mech. Therm.}, volume = { 23}, number = {SISSA;07/2011/M}, year = {2011}, publisher = {Springer}, chapter = {257}, abstract = {We study two variational models recently proposed in the literature to describe the mechanical behaviour of nematic elastomers either in the fully nonlinear regime or in the framework of a geometrically linear theory. We show that, in the small strain limit, the energy functional of the first one I\\\"-converges to the relaxation of the second one, a functional for which an explicit representation formula is available.

}, keywords = {Liquid crystals}, doi = {10.1007/s00161-011-0180-2}, url = {http://hdl.handle.net/1963/4141}, author = {Virginia Agostiniani and Antonio DeSimone} } @article {9991, title = {Generalised functions of bounded deformation}, journal = {J. Eur. Math. Soc. (JEMS), to appear}, year = {2011}, publisher = {SISSA}, abstract = {We introduce the space GBD of generalized functions of bounded deformation and study the structure properties of these functions: the rectifiability and the slicing properties of their jump sets, and the existence of their approximate symmetric gradients. We conclude by proving a compactness results for GBD, which leads to a compactness result for the space GSBD of generalized special functions of bounded deformation. The latter is connected to the existence of solutions to a weak formulation of some variational problems arising in fracture mechanics in the framework of linearized elasticity.

}, keywords = {free discontinuity problems, special functions of bounded deformation, jump set, rec- tifiability, slicing, approximate differentiability}, url = {http://hdl.handle.net/1963/6374}, author = {Gianni Dal Maso} } @article {2011, title = {Infinite-dimensional Frobenius manifolds for 2 + 1 integrable systems}, journal = {Matematische Annalen 349 (2011) 75-115}, number = {SISSA;12/2009/FM}, year = {2011}, publisher = {Springer}, abstract = {We introduce a structure of an infinite-dimensional Frobenius manifold on a subspace in the space of pairs of functions analytic inside/outside the unit circle with simple poles at 0/infinity respectively. The dispersionless 2D Toda equations are embedded into a bigger integrable hierarchy associated with this Frobenius manifold.}, doi = {10.1007/s00208-010-0509-3}, url = {http://hdl.handle.net/1963/3584}, author = {Guido Carlet and Boris Dubrovin and Luca Philippe Mertens} } @article {DAVENIA20115705, title = {Infinitely many positive solutions for a Schr{\"o}dinger{\textendash}Poisson system}, journal = {Nonlinear Analysis: Theory, Methods \& Applications}, volume = {74}, number = {16}, year = {2011}, pages = {5705 - 5721}, abstract = {We are interested in the existence of infinitely many positive solutions of the Schr{\"o}dinger{\textendash}Poisson system -Δu+u+V(|x|)ϕu=|u|p-1u,x∈R3,-Δϕ=V(|x|)u2,x∈R3, where V(|x|) is a positive bounded function, 1\<p\<5 and V(r

}, keywords = {Non-autonomous Schr{\"o}dinger{\textendash}Poisson system, Perturbation method}, issn = {0362-546X}, doi = {https://doi.org/10.1016/j.na.2011.05.057}, url = {http://www.sciencedirect.com/science/article/pii/S0362546X11003518}, author = {Pietro d{\textquoteright}Avenia and Alessio Pomponio and Giusi Vaira} } @article {2011, title = {Linearly degenerate Hamiltonian PDEs and a new class of solutions to the WDVV associativity equations}, journal = {Functional Analysis and Its Applications. Volume 45, Issue 4, December 2011, Pages 278-290}, year = {2011}, publisher = {Springer}, abstract = {We define a new class of solutions to the WDVV associativity equations. This class is determined by the property that one of the commuting PDEs associated with such a WDVV solution is linearly degenerate. We reduce the problem of classifying such solutions of the WDVV equations to the particular case of the so-called algebraic Riccati equation and, in this way, arrive at a complete classification of irreducible solutions.}, keywords = {Frobenius manifold}, doi = {10.1007/s10688-011-0030-9}, url = {http://hdl.handle.net/1963/6430}, author = {Boris Dubrovin and M.V. Pavlov and Sergei A. Zykov} } @article {Fedeli2011, title = {Metastable equilibria of capillary drops on solid surfaces: a phase field approach}, journal = {Continuum Mechanics and Thermodynamics}, volume = {23}, number = {5}, year = {2011}, month = {Sep}, pages = {453{\textendash}471}, abstract = {We discuss a phase field model for the numerical simulation of metastable equilibria of capillary drops resting on rough solid surfaces and for the description of contact angle hysteresis phenomena in wetting. The model is able to reproduce observed transitions of drops on micropillars from Cassie{\textendash}Baxter to Wenzel states. When supplemented with a dissipation potential which describes energy losses due to frictional forces resisting the motion of the contact line, the model can describe metastable states such as drops in equilibrium on vertical glass plates. The reliability of the model is assessed by a detailed comparison of its predictions with experimental data on the maximal size of water drops that can stick on vertical glass plates which have undergone different surface treatments.

}, issn = {1432-0959}, doi = {10.1007/s00161-011-0189-6}, url = {https://doi.org/10.1007/s00161-011-0189-6}, author = {Livio Fedeli and Turco, Alessandro and Antonio DeSimone} } @article {de2011multiplicity, title = {Multiplicity of solutions for a mean field equation on compact surfaces}, journal = {Boll. Unione Mat. Ital.(9)}, volume = {4}, year = {2011}, pages = {245{\textendash}257}, abstract = {We consider a scalar field equation on compact surfaces which has variational structure. When the surface is a torus and a physical parameter ρ belongs to $(8\pi, 4\pi^2 )$ we show under some extra assumptions that, as conjectured in [9], the functional admits at least three saddle points other than a local minimum.

}, author = {Francesca De Marchis} } @article {2011, title = {On the number of eigenvalues of a model operator related to a system of three particles on lattices}, journal = {J. Phys. A 44 (2011) 315302}, year = {2011}, publisher = {IOP Publishing}, doi = {10.1088/1751-8113/44/31/315302}, url = {http://hdl.handle.net/1963/5496}, author = {Gianfausto Dell{\textquoteright}Antonio and Zahriddin I. Muminov and Y.M. Shermatova} } @article {2011, title = {Numerical Strategies for Stroke Optimization of Axisymmetric Microswimmers}, journal = {Mathematical Models and Methods in Applied Sciences 21 (2011) 361-387}, number = {SISSA;33/2009/M}, year = {2011}, publisher = {World Scientific}, abstract = {We propose a computational method to solve optimal swimming problems, based on the boundary integral formulation of the hydrodynamic interaction between swimmer and surrounding fluid and direct constrained minimization of the energy consumed by the swimmer. We apply our method to axisymmetric model examples. We consider a classical model swimmer (the three-sphere swimmer of Golestanian et al.) as well as a novel axisymmetric swimmer inspired by the observation of biological micro-organisms.}, keywords = {Optimal swimming}, doi = {10.1142/S0218202511005088}, url = {http://hdl.handle.net/1963/3657}, author = {Fran{\c c}ois Alouges and Antonio DeSimone and Luca Heltai} } @article {2011, title = {Numerical Study of breakup in generalized Korteweg-de Vries and Kawahara equations}, journal = {SIAM J. Appl. Math. 71 (2011) 983-1008}, number = {arXiv:1101.0268;}, year = {2011}, publisher = {SIAM}, abstract = {This article is concerned with a conjecture in [B. Dubrovin, Comm. Math. Phys., 267 (2006), pp. 117{\textendash}139] on the formation of dispersive shocks in a class of Hamiltonian dispersive regularizations of the quasi-linear transport equation. The regularizations are characterized by two arbitrary functions of one variable, where the condition of integrability implies that one of these functions must not vanish. It is shown numerically for a large class of equations that the local behavior of their solution near the point of gradient catastrophe for the transport equation is described by a special solution of a Painlev{\'e}-type equation. This local description holds also for solutions to equations where blowup can occur in finite time. Furthermore, it is shown that a solution of the dispersive equations away from the point of gradient catastrophe is approximated by a solution of the transport equation with the same initial data, modulo terms of order $\\\\epsilon^2$, where $\\\\epsilon^2$ is the small dispersion parameter. Corrections up to order $\\\\epsilon^4$ are obtained and tested numerically.}, doi = {10.1137/100819783}, url = {http://hdl.handle.net/1963/4951}, author = {Boris Dubrovin and Tamara Grava and Christian Klein} } @article {1110.6124, title = {A planar bi-Lipschitz extension Theorem}, year = {2011}, url = {http://arxiv.org/abs/1110.6124}, author = {Sara Daneri and Aldo Pratelli} } @article {2011, title = {Poincar{\'e} covariance and κ-Minkowski spacetime}, journal = {Physics Letters A 375 (2011) 3496-3498}, number = {SISSA;43/2010/FM}, year = {2011}, publisher = {Elsevier}, abstract = {A fully Poincar{\'e} covariant model is constructed out of the k-Minkowski spacetime. Covariance is implemented by a unitary representation of the Poincar{\'e} group, and thus complies with the original Wigner approach to quantum symmetries. This provides yet another example (besides the DFR model), where Poincar{\'e} covariance is realised {\'a} la Wigner in the presence of two characteristic dimensionful parameters: the light speed and the Planck length. In other words, a Doubly Special Relativity (DSR) framework may well be realised without deforming the meaning of \\\"Poincar{\'e} covariance\\\".}, doi = {10.1016/j.physleta.2011.08.011}, url = {http://hdl.handle.net/1963/3893}, author = {Ludwik Dabrowski and Gherardo Piacitelli} } @article {2011, title = {Product of real spectral triples}, journal = {International Journal of Geometric Methods in Modern Physics 8 (2011) 1833-1848}, number = {arXiv:1011.4456;}, year = {2011}, note = {Based on the talk given at the conference \\\"Noncommutative Geometry and Quantum Physics, Vietri sul Mare, Aug 31 - Sept 5, 2009\\\"}, publisher = {World Scientific}, abstract = {We construct the product of real spectral triples of arbitrary finite dimension (and arbitrary parity) taking into account the fact that in the even case there are two possible real structures, in the odd case there are two inequivalent representations of the gamma matrices (Clifford algebra), and in the even-even case there are two natural candidates for the Dirac operator of the product triple.}, doi = {10.1142/S021988781100597X}, url = {http://hdl.handle.net/1963/5510}, author = {Ludwik Dabrowski and Giacomo Dossena} } @article {2011, title = {Quantum Geometry on Quantum Spacetime: Distance, Area and Volume Operators}, journal = {Commun. Math. Phys. 308 (2011) 567-589}, number = {arXiv:1005.2130;}, year = {2011}, publisher = {Springer}, abstract = {We develop the first steps towards an analysis of geometry on the quantum\\r\\nspacetime proposed in Doplicher et al. (Commun Math Phys 172:187{\textendash}220, 1995). The homogeneous elements of the universal differential algebra are naturally identified with operators living in tensor powers of Quantum Spacetime; this allows us to compute their spectra. In particular, we consider operators that can be interpreted as distances, areas, 3- and 4-volumes. The Minkowski distance operator between two independent events is shown to have pure Lebesgue spectrum with infinite multiplicity. The Euclidean distance operator is shown to have spectrum bounded below by a constant of the order of the Planck length. The corresponding statement is proved also for both the space-space and space-time area operators, as well as for the Euclidean length of the vector representing the 3-volume operators. However, the space 3-volume operator (the time component of that vector) is shown to have spectrum equal to the whole complex plane. All these operators are normal, while the distance operators are also selfadjoint. The Lorentz invariant spacetime volume operator, representing the 4- volume spanned by five\\r\\nindependent events, is shown to be normal. Its spectrum is pure point with a\\r\\nfinite distance (of the order of the fourth power of the Planck length) away\\r\\nfrom the origin. The mathematical formalism apt to these problems is developed and its relation to a general formulation of Gauge Theories on Quantum Spaces is outlined. As a byproduct, a Hodge Duality between the absolute differential and the Hochschild boundary is pointed out.}, doi = {10.1007/s00220-011-1358-y}, url = {http://hdl.handle.net/1963/5203}, author = {Dorothea Bahns and Sergio Doplicher and Klaus Fredenhagen and Gherardo Piacitelli} } @article {2011, title = {Quantum Isometries of the finite noncommutative geometry of the Standard Model}, journal = {Commun. Math. Phys. 307:101-131, 2011}, number = {arXiv:1009.2850;}, year = {2011}, publisher = {Springer}, abstract = {We compute the quantum isometry group of the finite noncommutative geometry F describing the internal degrees of freedom in the Standard Model of particle physics. We show that this provides genuine quantum symmetries of the spectral triple corresponding to M x F where M is a compact spin manifold. We also prove that the bosonic and fermionic part of the spectral action are preserved by these symmetries.}, doi = {10.1007/s00220-011-1301-2}, url = {http://hdl.handle.net/1963/4906}, author = {Jyotishman Bhowmick and Francesco D{\textquoteright}Andrea and Ludwik Dabrowski} } @article {2011, title = {Quasiconvex envelopes of energies for nematic elastomers in the small strain regime and applications}, journal = {Journal of the Mechanics and Physics of Solids 59 (2011) 787-803}, number = {SISSA;62/2010/M}, year = {2011}, abstract = {We provide some explicit formulas for the quasiconvex envelope of energy densities for nematic elastomers in the small strain regime and plane strain conditions. We then demonstrate their use as a powerful tool for the interpretation of mechanical experiments.}, url = {http://hdl.handle.net/1963/4065}, author = {Pierluigi Cesana and Antonio DeSimone} } @article {2011, title = {Quasistatic evolution for Cam-Clay plasticity: a weak formulation via viscoplastic regularization and time rescaling}, journal = {Calculus of Variations and Partial Differential Equations 40 (2011) 125-181}, number = {SISSA;36/2009/M}, year = {2011}, publisher = {Springer}, abstract = {Cam-Clay nonassociative plasticity exhibits both hardening and softening behaviour, depending on the loading. For many initial data the classical formulation of the quasistatic evolution problem has no smooth solution. We propose here a notion of generalized solution, based on a viscoplastic approximation. To study the limit of the viscoplastic evolutions we rescale time, in such a way that the plastic strain is uniformly Lipschitz with respect to the rescaled time. The limit of these rescaled solutions, as the viscosity parameter tends to zero, is characterized through an energy-dissipation balance, that can be written in a natural way using the rescaled time. As shown in [4] and [6], the proposed solution may be discontinuous with respect to the original time. Our formulation allows to compute the amount of viscous dissipation occurring instantaneously at each discontinuity time.

}, keywords = {Cam-Clay plasticity}, doi = {10.1007/s00526-010-0336-0}, url = {http://hdl.handle.net/1963/3670}, author = {Gianni Dal Maso and Antonio DeSimone and Francesco Solombrino} } @article {2011, title = {Quasistatic evolution of sessile drops and contact angle hysteresis}, journal = {Arch. Rational Mech. Anal. 202 (2011) 295-348}, year = {2011}, publisher = {Springer}, abstract = {We consider the classical model of capillarity coupled with a rate-independent dissipation mechanism due to frictional forces acting on the contact line, and prove the existence of quasistatic evolutions with prescribed initial configuration. We also discuss in detail some explicit solutions to show that the model does account for contact angle hysteresis, and to compare its predictions with experimental observations.}, doi = {10.1007/s00205-011-0427-x}, url = {http://hdl.handle.net/1963/4912}, author = {Giovanni Alberti and Antonio DeSimone} } @article {2011, title = {SBV regularity for Hamilton-Jacobi equations in R^n}, journal = {Arch. Rational Mech. Anal. 200 (2011) 1003-1021}, number = {arXiv:1002.4087;}, year = {2011}, publisher = {Springer}, abstract = {In this paper we study the regularity of viscosity solutions to the following Hamilton-Jacobi equations $$ \partial_t u + H(D_{x} u)=0 \qquad \textrm{in}\quad \Omega\subset \mathbb{R}\times \mathbb{R}^{n} . $$ In particular, under the assumption that the Hamiltonian $H\in C^2(\mathbb{R}^n)$ is uniformly convex, we prove that $D_{x}u$ and $\partial_t u$ belong to the class $SBV_{loc}(\Omega)$.

}, doi = {10.1007/s00205-010-0381-z}, url = {http://hdl.handle.net/1963/4911}, author = {Stefano Bianchini and Camillo De Lellis and Roger Robyr} } @article {2011, title = {Singular perturbation models in phase transitions for second order materials}, journal = {Indiana Univ. Math. J. 60 (2011) 367-409}, number = {SISSA;20/2010/M}, year = {2011}, publisher = {Indiana University}, abstract = {A variational model proposed in the physics literature to describe the onset of pattern formation in two-component bilayer membranes and amphiphilic monolayers leads to the analysis of a Ginzburg-Landau type energy with a negative term depending on the first derivative of the phase function. Scaling arguments motivate the study of the family of second order singular perturbed energies Fe having a negative term depending on the first derivative of the phase function. Here, the asymptotic behavior of {Fe} is studied using G-convergence techniques. In particular, compactness results and an integral representation of the limit energy are obtained.}, doi = {10.1512/iumj.2011.60.4346}, url = {http://hdl.handle.net/1963/3858}, author = {Milena Chermisi and Gianni Dal Maso and Irene Fonseca and Giovanni Leoni} } @article {2011, title = {Supercritical conformal metrics on surfaces with conical singularities}, journal = {Int Math Res Notices (2011) 2011 (24): 5625-5643}, number = {SISSA;56/2010/M}, year = {2011}, publisher = {Oxford University Press}, abstract = {We study the problem of prescribing the Gaussian curvature on surfaces with conical singularities in supercritical regimes. Using a Morse-theoretical approach we prove a general existence theorem on surfaces with positive genus, with a generic multiplicity result.

}, doi = {10.1093/imrn/rnq285}, url = {http://hdl.handle.net/1963/4095}, author = {Mauro Bardelloni and Francesca De Marchis and Andrea Malchiodi} } @article {1106.6245, title = {Thin-walled beams with a cross-section of arbitrary geometry: derivation of linear theories starting from 3D nonlinear elasticity}, year = {2011}, abstract = {The subject of this paper is the rigorous derivation of lower dimensional models for a nonlinearly elastic thin-walled beam whose cross-section is given by a thin tubular neighbourhood of a smooth curve. Denoting by h and δ_h, respectively, the diameter and the thickness of the cross-section, we analyse the case where the scaling factor of the elastic energy is of order ε_h^2, with ε_h/δ_h^2 \rightarrow l \in [0, +\infty). Different linearized models are deduced according to the relative order of magnitude of δ_h with respect to h.

}, author = {Elisa Davoli} } @article {DANCHIN2011253, title = {The well-posedness issue for the density-dependent Euler equations in endpoint Besov spaces}, journal = {Journal de Math{\'e}matiques Pures et Appliqu{\'e}es}, volume = {96}, number = {3}, year = {2011}, pages = {253 - 278}, abstract = {This work is the continuation of the recent paper (Danchin, 2010) [9] devoted to the density-dependent incompressible Euler equations. Here we concentrate on the well-posedness issue in Besov spaces of type B$\infty$,rs embedded in the set of Lipschitz continuous functions, a functional framework which contains the particular case of H{\"o}lder spaces C1,α and of the endpoint Besov space B$\infty$,11. For such data and under the non-vacuum assumption, we establish the local well-posedness and a continuation criterion in the spirit of that of Beale, Kato and Majda (1984) [2]. In the last part of the paper, we give lower bounds for the lifespan of a solution. In dimension two, we point out that the lifespan tends to infinity when the initial density tends to be a constant. This is, to our knowledge, the first result of this kind for the density-dependent incompressible Euler equations. R{\'e}sum{\'e} Ce travail compl{\`e}te l'article r{\'e}cent (Danchin, 2010) [9] consacr{\'e} au syst{\`e}me d'Euler incompressible {\`a} densit{\'e} variable. Lorsque l'{\'e}tat initial ne comporte pas de vide, on montre ici que le syst{\`e}me est bien pos{\'e} dans tous les espaces de Besov B$\infty$,rs inclus dans l'ensemble des fonctions lipschitziennes. Ce cadre fonctionnel contient en particulier les espaces de H{\"o}lder C1,α et l'espace de Besov limite B$\infty$,11. On {\'e}tablit {\'e}galement un crit{\`e}re de prolongement dans l'esprit de celui de Beale, Kato et Majda (1984) [2] pour le cas homog{\`e}ne. Dans la derni{\`e}re partie de l'article, on donne des minorations pour le temps de vie des solutions du syst{\`e}me. En dimension deux, on montre que ce temps de vie tend vers l'infini lorsque la densit{\'e} tend {\`a} {\^e}tre homog{\`e}ne. {\`A} notre connaissance, il s'agit du premier r{\'e}sultat de ce type pour le syst{\`e}me d'Euler incompressible {\`a} densit{\'e} variable.

}, keywords = {Blow-up criterion, Critical regularity, Incompressible Euler equations, Lifespan, Nonhomogeneous inviscid fluids}, issn = {0021-7824}, doi = {https://doi.org/10.1016/j.matpur.2011.04.005}, url = {http://www.sciencedirect.com/science/article/pii/S0021782411000511}, author = {Rapha{\"e}l Danchin and Francesco Fanelli} } @article {2010, title = {Canonical k-Minkowski Spacetime}, number = {SISSA;26/2010/FM}, year = {2010}, abstract = {A complete classification of the regular representations of the relations [T,X_j] = (i/k)X_j, j=1,...,d, is given. The quantisation of RxR^d canonically (in the sense of Weyl) associated with the universal representation of the above relations is intrinsically \\\"radial\\\", this meaning that it only involves the time variable and the distance from the origin; angle variables remain classical. The time axis through the origin is a spectral singularity of the model: in the large scale limit it is topologically disjoint from the rest. The symbolic calculus is developed; in particular there is a trace functional on symbols. For suitable choices of states localised very close to the origin, the uncertainties of all spacetime coordinates can be made simultaneously small at wish. On the contrary, uncertainty relations become important at \\\"large\\\" distances: Planck scale effects should be visible at LHC energies, if processes are spread in a region of size 1mm (order of peak nominal beam size) around the origin of spacetime.}, url = {http://hdl.handle.net/1963/3863}, author = {Gherardo Piacitelli and Ludwik Dabrowski} } @article {2010, title = {Convergence of equilibria of thin elastic rods under physical growth conditions for the energy density}, number = {SISSA;67/2010/M}, year = {2010}, abstract = {The subject of this paper is the study of the asymptotic behaviour of the equilibrium configurations of a nonlinearly elastic thin rod, as the diameter of the cross-section tends to zero. Convergence results are established assuming physical growth conditions for the elastic energy density and suitable scalings of the applied loads, that correspond at the limit to different rod models: the constrained linear theory, the analogous of von K{\'a}rm{\'a}n plate theory for rods, and the linear theory.}, url = {http://hdl.handle.net/1963/4086}, author = {Elisa Davoli and Maria Giovanna Mora} } @article {2010, title = {Dirac Operators on Quantum Projective Spaces}, journal = {Comm. Math. Phys. 295 (2010) 731-790}, number = {SISSA;17/2009/FM}, year = {2010}, note = {Quantum Algebra}, abstract = {We construct a family of self-adjoint operators D_N which have compact resolvent and bounded commutators with the coordinate algebra of the quantum projective space CP_q(l), for any l>1 and 0We consider the disintegration of the Lebesgue measure on the graph of a convex function f:\\\\Rn-\> \\\\R w.r.t. the partition into its faces, which are convex sets and therefore have a well defined linear dimension, and we prove that each conditional measure is equivalent to the k-dimensional Hausdorff measure of the k-dimensional face on which it is concentrated. The remarkable fact is that a priori the directions of the faces are just Borel and no Lipschitz regularity is known. Notwithstanding that, we also prove that a Green-Gauss formula for these directions holds on special sets.}, doi = {10.1016/j.jfa.2010.01.024}, url = {http://hdl.handle.net/1963/3622}, author = {Laura Caravenna and Sara Daneri} } @article {2010, title = {Effective Schroedinger dynamics on $ ε$-thin Dirichlet waveguides via Quantum Graphs I: star-shaped graphs}, journal = {J. Phys. A 43 (2010) 474014}, number = {arXiv.org;1004.4750v2}, year = {2010}, publisher = {IOP Publishing}, abstract = {We describe the boundary conditions at the vertex that one must choose to obtain a dynamical system that best describes the low-energy part of the evolution of a quantum system confined to a very small neighbourhood of a star-shaped metric graph.}, doi = {10.1088/1751-8113/43/47/474014}, url = {http://hdl.handle.net/1963/4106}, author = {Gianfausto Dell{\textquoteright}Antonio and Emanuele Costa} } @article {DEMARCHIS20102165, title = {Generic multiplicity for a scalar field equation on compact surfaces}, journal = {Journal of Functional Analysis}, volume = {259}, number = {8}, year = {2010}, pages = {2165 - 2192}, abstract = {We prove generic multiplicity of solutions for a scalar field equation on compact surfaces via Morse inequalities. In particular our result improves significantly the multiplicity estimate which can be deduced from the degree-counting formula in Chen and Lin (2003) [12]. Related results are derived for the prescribed Q-curvature equation.

}, keywords = {Generic multiplicity, Geometric PDE{\textquoteright}s, Morse inequalities, Scalar field equations}, issn = {0022-1236}, doi = {https://doi.org/10.1016/j.jfa.2010.07.003}, url = {http://www.sciencedirect.com/science/article/pii/S0022123610002697}, author = {Francesca De Marchis} } @article {2010, title = {The geometry emerging from the symmetries of a quantum system}, number = {SISSA;72/2009/FM}, year = {2010}, abstract = {We investigate the relation between the symmetries of a quantum system and its topological quantum numbers, in a general C*-algebraic framework. We prove that, under suitable assumptions on the symmetry algebra, there exists a generalization of the Bloch-Floquet transform which induces a direct-integral decomposition of the algebra of observables. Such generalized transform selects uniquely the set of \\\"continuous sections\\\" in the direct integral, thus yielding a Hilbert bundle. The emerging geometric structure provides some topological invariants of the quantum system. Two running examples provide an Ariadne\\\'s thread through the paper. For the sake of completeness, we review two related theorems by von Neumann and Maurin and compare them with our result.}, url = {http://hdl.handle.net/1963/3834}, author = {Giuseppe De Nittis and Gianluca Panati} } @article {2010, title = {Hamiltonian PDEs: deformations, integrability, solutions}, journal = {Journal of Physics A: Mathematical and Theoretical. Volume 43, Issue 43, 29 October 2010, Article number 434002}, year = {2010}, publisher = {SISSA}, abstract = {We review recent classification results on the theory of systems of nonlinear\\r\\nHamiltonian partial differential equations with one spatial dimension, including\\r\\na perturbative approach to the integrability theory of such systems, and discuss\\r\\nuniversality conjectures describing critical behaviour of solutions to such\\r\\nsystems.}, doi = {10.1088/1751-8113/43/43/434002}, url = {http://hdl.handle.net/1963/6469}, author = {Boris Dubrovin} } @article {2010, title = {Homogenization of fiber reinforced brittle material: the intermediate case}, journal = {Adv. Calc. Var. 3 (2010) 345-370}, number = {SISSA;14/2009/M}, year = {2010}, publisher = {Walter de Gruyter}, abstract = {We derive a cohesive fracture model by homogenizing a periodic composite material whose microstructure is characterized by the presence of brittle inclusions in a reticulated unbreakable elastic structure.}, doi = {10.1515/ACV.2010.011}, url = {http://hdl.handle.net/1963/3607}, author = {Gianni Dal Maso and Caterina Ida Zeppieri} } @article {2010, title = {Lorentz Covariant k-Minkowski Spacetime}, journal = {Phys. Rev. D 81 (2010) 125024}, number = {SISSA;04/2010/FM}, year = {2010}, abstract = {In recent years, different views on the interpretation of Lorentz covariance of non commuting coordinates were discussed. Here, by a general procedure, we construct the minimal canonical central covariantisation of the k-Minkowski spacetime. We then show that, though the usual k-Minkowski spacetime is covariant under deformed (or twisted) Lorentz action, the resulting framework is equivalent to taking a non covariant restriction of the covariantised model. We conclude with some general comments on the approach of deformed covariance.}, doi = {10.1103/PhysRevD.81.125024}, url = {http://hdl.handle.net/1963/3829}, author = {Ludwik Dabrowski and Michal Godlinski and Gherardo Piacitelli} } @article {2010, title = {Nonlocal character of the reduced theory of thin films with higher order perturbations}, journal = {Adv. Calc. Var. 3 (2010) 287-319}, number = {SISSA;57/2009/M}, year = {2010}, doi = {10.1515/ACV.2010.012, /July/2010}, url = {http://hdl.handle.net/1963/3754}, author = {Gianni Dal Maso and Irene Fonseca and Giovanni Leoni} } @article {2010, title = {Optimally swimming Stokesian Robots}, number = {SISSA;54/2010/M}, year = {2010}, abstract = {We study self propelled stokesian robots composed of assemblies of balls, in dimen-\\nsions 2 and 3, and prove that they are able to control their position and orientation. This is a result of controllability, and its proof relies on applying Chow\\\'s theorem in an analytic framework, similarly to what has been done in [3] for an axisymmetric system swimming along the axis of symmetry. However, we simplify drastically\\nthe analyticity result given in [3] and apply it to a situation where more complex swimmers move either in a plane or in three-dimensional space, hence experiencing also rotations. We then focus our attention on energetically optimal strokes, which we are able to compute numerically. Some examples of computed optimal strokes are discussed in detail.}, url = {http://hdl.handle.net/1963/3929}, author = {Fran{\c c}ois Alouges and Antonio DeSimone and Luca Heltai and Aline Lefebvre and Benoit Merlet} } @conference {10.1007/978-90-481-9195-6_4, title = {A Phase Field Approach to Wetting and Contact Angle Hysteresis Phenomena}, booktitle = {IUTAM Symposium on Variational Concepts with Applications to the Mechanics of Materials}, year = {2010}, pages = {51{\textendash}63}, publisher = {Springer Netherlands}, organization = {Springer Netherlands}, address = {Dordrecht}, abstract = {We discuss a phase field model for the numerical simulation of contact angle hysteresis phenomena in wetting. The performance of the model is assessed by comparing its predictions with experimental data on the critical size of drops that can stick on a vertical glass plate.

}, isbn = {978-90-481-9195-6}, author = {Antonio DeSimone and Livio Fedeli and Turco, Alessandro}, editor = {Hackl, Klaus} } @article {2010, title = {Quasistatic crack growth in elasto-plastic materials: the two-dimensional case}, journal = {Arch. Ration. Mech. Anal. 196 (2010) 867-906}, number = {SISSA;62/2008/M}, year = {2010}, abstract = {We study a variational model for the quasistatic evolution of elasto-plastic materials with cracks in the case of planar small strain associative elasto-plasticity.}, doi = {10.1007/s00205-009-0258-1}, url = {http://hdl.handle.net/1963/2964}, author = {Gianni Dal Maso and Rodica Toader} } @article {2010, title = {Quasistatic crack growth in finite elasticity with non-interpenetration}, journal = {Ann. Inst. H. Poincare Anal. Non Lineaire 27 (2010) 257-290}, number = {SISSA;80/2008/M}, year = {2010}, abstract = {We present a variational model to study the quasistatic growth of brittle cracks in hyperelastic materials, in the framework of finite elasticity, taking\\ninto account the non-interpenetration condition.

}, doi = {10.1016/j.anihpc.2009.09.006}, url = {http://hdl.handle.net/1963/3397}, author = {Gianni Dal Maso and Giuliano Lazzaroni} } @article {2010, title = {Quasistatic evolution for Cam-Clay plasticity: the spatially homogeneous case}, journal = {Netw. Heterog. Media 5 (2010) 97-132}, number = {SISSA;39/2009/M}, year = {2010}, abstract = {We study the spatially uniform case of the problem of quasistatic evolution in small strain nonassociative elastoplasticity (Cam-Clay model). Through the introdution of a viscous approximation, the problem reduces to determine the limit behavior of the solutions of a singularly perturbed system of ODE\\\'s in a finite dimensional Banach space. Depending on the sign of two explicit scalar indicators, we see that the limit dynamics presents, under quite generic assumptions, the alternation of three possible regimes: the elastic regime, when the limit equation is just the equation of linearized elasticity, the slow dynamics, when the strain evolves smoothly on the yield surface and plastic flow is produced, and the fast dynamics, which may happen only in the softening regime, where\\nviscous solutions exhibit a jump across a heteroclinic orbit of an auxiliary system.

}, keywords = {Cam-Clay plasticity}, doi = {10.3934/nhm.2010.5.97}, url = {http://hdl.handle.net/1963/3671}, author = {Gianni Dal Maso and Francesco Solombrino} } @article {2010, title = {The role of membrane viscosity in the dynamics of fluid membranes}, number = {SISSA;55/2010/M}, year = {2010}, abstract = {Fluid membranes made out of lipid bilayers are the fundamental separation structure in eukaryotic cells. Many physiological processes rely on dramatic shape and topological changes (e.g. fusion, fission) of fluid membrane systems. Fluidity is key to the versatility and constant reorganization of lipid bilayers. Here, we study the role of the membrane intrinsic viscosity, arising from the friction of the lipid molecules as they rearrange to accommodate shape changes, in the dynamics of morphological changes of fluid vesicles. In particular, we analyze the competition between the membrane viscosity and the viscosity of the bulk fluid surrounding the vesicle as the dominant dissipative mechanism. We consider the relaxation dynamics of fluid vesicles put in an out-of-equilibrium state, but conclusions can be drawn regarding the kinetics or power consumption in regulated shape changes in the cell. On the basis of numerical calculations, we find that the dynamics arising from the membrane viscosity are qualitatively different from the dynamics arising from the bulk viscosity. When these two dissipation mechanisms are put in competition, we find that for small vesicles the membrane dissipation dominates, with a relaxation time that scales as the size of the vesicle to the power 2. For large vesicles, the bulk dissipation dominates, and the exponent in the relaxation time vs. size relation is 3.}, url = {http://hdl.handle.net/1963/3930}, author = {Marino Arroyo and Antonio DeSimone and Luca Heltai} } @article {2010, title = {A time-dependent perturbative analysis for a quantum particle in a cloud chamber}, journal = {Annales Henri Poincare 11 (2010) 539-564}, number = {arXiv.org;0907.5503v1}, year = {2010}, publisher = {Springer}, abstract = {We consider a simple model of a cloud chamber consisting of a test particle (the alpha-particle) interacting with two other particles (the atoms of the vapour) subject to attractive potentials centered in $a_1, a_2 \\\\in \\\\mathbb{R}^3$. At time zero the alpha-particle is described by an outgoing spherical wave centered in the origin and the atoms are in their ground state. We show that, under suitable assumptions on the physical parameters of the system and up to second order in perturbation theory, the probability that both atoms are ionized is negligible unless $a_2$ lies on the line joining the origin with $a_1$. The work is a fully time-dependent version of the original analysis proposed by Mott in 1929.}, doi = {10.1007/s00023-010-0037-4}, url = {http://hdl.handle.net/1963/3969}, author = {Gianfausto Dell{\textquoteright}Antonio and Rodolfo Figari and Alessandro Teta} } @inbook {2009, title = {Biological Fluid Dynamics, Non-linear Partial Differential Equations}, booktitle = {Encyclopedia of Complexity and Systems Science / Robert A. Meyers (ed.). - Springer, 2009, 548-554}, number = {SISSA;21/2008/M}, year = {2009}, url = {http://hdl.handle.net/1963/2630}, author = {Antonio DeSimone and Fran{\c c}ois Alouges and Aline Lefebvre} } @article {2009, title = {On the convergence of viscous approximations after shock interactions}, journal = {Discrete Contin. Dyn. Syst. 23 (2009) 29-48}, year = {2009}, publisher = {American Institute of Mathematical Sciences}, abstract = {We consider a piecewise smooth solution to a scalar conservation law, with possibly interacting shocks. We show that, after the interactions have taken place, vanishing viscosity approximations can still be represented by a regular expansion on smooth regions and by a singular perturbation expansion near the shocks, in terms of powers of the viscosity coefficient.}, doi = {10.3934/dcds.2009.23.29}, url = {http://hdl.handle.net/1963/3412}, author = {Alberto Bressan and Carlotta Donadello} } @article {2009, title = {Discrete-to-continuum limits for strain-alignment-coupled systems: Magnetostrictive solids, ferroelectric crystals and nematic elastomers}, journal = {Netw. Heterog. Media 4 (2009) 667-708}, year = {2009}, publisher = {American Institute of Mathematical Sciences}, abstract = {In the framework of linear elasticity, we study the limit of a class of discrete free energies modeling strain-alignment-coupled systems by a rigorous coarse-graining procedure, as the number of molecules diverges. We focus on three paradigmatic examples: magnetostrictive solids, ferroelectric crystals and nematic elastomers, obtaining in the limit three continuum models consistent with those commonly employed in the current literature. We also derive the correspondent macroscopic energies in the presence of displacement boundary conditions and of various kinds of applied external fields.}, doi = {10.3934/nhm.2009.4.667}, url = {http://hdl.handle.net/1963/3788}, author = {Marco Cicalese and Antonio DeSimone and Caterina Ida Zeppieri} } @inbook {2009, title = {Hamiltonian perturbations of hyperbolic PDEs: from classification results to the properties of solutions}, booktitle = {New Trends in Mathematical Physics : Selected contributions of the XVth International Congress on Mathematical Physics, Springer Netherlands, 2009, pp. 231-276.}, year = {2009}, publisher = {SISSA}, organization = {SISSA}, abstract = {We begin with presentation of classi cation results in the theory of Hamiltonian\\r\\nPDEs with one spatial dimension depending on a small parameter. Special\\r\\nattention is paid to the deformation theory of integrable hierarchies, including an\\r\\nimportant subclass of the so-called integrable hierarchies of the topological type\\r\\nassociated with semisimple Frobenius manifolds. Many well known equations of\\r\\nmathematical physics, such as KdV, NLS, Toda, Boussinesq etc., belong to this\\r\\nsubclass, but there are many new integrable PDEs, some of them being of interest\\r\\nfor applications. Connections with the theory of Gromov{Witten invariants\\r\\nand random matrices are outlined. We then address the problem of comparative\\r\\nstudy of singularities of solutions to the systems of first order quasilinear\\r\\nPDEs and their Hamiltonian perturbations containing higher derivatives. We\\r\\nformulate Universality Conjectures describing different types of critical behavior\\r\\nof perturbed solutions near the point of gradient catastrophe of the unperturbed\\r\\none.}, isbn = {978-90-481-2810-5}, url = {http://hdl.handle.net/1963/6470}, author = {Boris Dubrovin} } @article {2009, title = {A higher order model for image restoration: the one dimensional case}, journal = {SIAM J. Math. Anal. 40 (2009) 2351-2391}, number = {SISSA;66/2008/M}, year = {2009}, abstract = {The higher order total variation-based model for image restoration proposed by Chan, Marquina, and Mulet in [6] is analyzed in one dimension. A suitable functional framework in which the minimization problem is well posed is being proposed and it is proved analytically that the\\nhigher order regularizing term prevents the occurrence of the staircase effect. The generalized version of the model considered here includes, as particular cases, some curvature dependent functionals.}, doi = {10.1137/070697823}, url = {http://hdl.handle.net/1963/3174}, author = {Gianni Dal Maso and Irene Fonseca and Giovanni Leoni and Massimiliano Morini} } @article {2009, title = {Homogenization of fiber reinforced brittle materials: the extremal cases}, journal = {SIAM J. Math. Anal. 41 (2009) 1874-1889}, number = {SISSA;49/2008/M}, year = {2009}, publisher = {SIAM}, abstract = {We analyze the behavior of a fragile material reinforced by a reticulated elastic unbreakable structure in the case of antiplane shear. The microscopic geometry of this material is described by means of two small parameters: the period $\\\\varepsilon$ of the grid and the ratio $\\\\delta$ between the thickness of the fibers and the period $\\\\varepsilon$. We show that the asymptotic behavior as $\\\\varepsilon\\\\to0^+$ and $\\\\delta\\\\to0^+$ depends dramatically on the relative size of these parameters. Indeed, in the two cases considered, i.e., $\\\\varepsilon\\\\ll\\\\delta$ and $\\\\varepsilon\\\\gg\\\\delta$, we obtain two different limit models: a perfectly elastic model and an elastic model with macroscopic cracks, respectively.}, url = {http://hdl.handle.net/1963/2705}, author = {Marco Barchiesi and Gianni Dal Maso} } @article {2009, title = {Quasistatic evolution for Cam-Clay plasticity: examples of spatially homogeneous solutions}, journal = {Math. Models Methods Appl. Sci. 19 (2009) 1643-1711}, number = {SISSA;78/2008/M}, year = {2009}, abstract = {We study a quasistatic evolution problem for Cam-Clay plasticity under a special loading program which leads to spatially homogeneous solutions. Under some initial conditions, the solutions exhibit a softening behaviour and time discontinuities.\\nThe behavior of the solutions at the jump times is studied by a viscous approximation.}, doi = {10.1142/S0218202509003942}, url = {http://hdl.handle.net/1963/3395}, author = {Gianni Dal Maso and Antonio DeSimone} } @article {2009, title = {Relaxation dynamics of fluid membranes}, journal = {Phys. Rev. E 79 (2009) 031915}, year = {2009}, publisher = {American Physical Society}, abstract = {We study the effect of membrane viscosity in the dynamics of liquid membranes-possibly with free or internal boundaries-driven by conservative forces (curvature elasticity and line tension) and dragged by the bulk dissipation of the ambient fluid and the friction occurring when the amphiphilic molecules move relative to each other. To this end, we formulate a continuum model which includes a form of the governing equations for a two-dimensional viscous fluid moving on a curved, time-evolving surface. The effect of membrane viscosity has received very limited attention in previous continuum studies of the dynamics of fluid membranes, although recent coarse-grained discrete simulations suggest its importance. By applying our model to the study of vesiculation and membrane fusion in a simplified geometry, we conclude that membrane viscosity plays a dominant role in the relaxation dynamics of fluid membranes of sizes comparable to those found in eukaryotic cells, and is not negligible in many large synthetic systems of current interest.}, doi = {10.1103/PhysRevE.79.031915}, url = {http://hdl.handle.net/1963/3618}, author = {Marino Arroyo and Antonio DeSimone} } @article {2009, title = {Strain-order coupling in nematic elastomers: equilibrium configurations}, journal = {Math. Models Methods Appl. Sci. 19 (2009) 601-630}, number = {SISSA;24/2008/M}, year = {2009}, abstract = {We consider models that describe liquid crystal elastomers either in a biaxial or in a uniaxial phase and in the framework of Frank\\\'s director theory. We prove existence of static equilibrium solutions in the presence of frustrations due to electro-mechanical boundary conditions and to applied loads and fields. We find explicit solutions arising in connection with special boundary conditions and the corresponding phase diagrams, leading to significant implications on possible experimental observations.}, url = {http://hdl.handle.net/1963/2700}, author = {Pierluigi Cesana and Antonio DeSimone} } @article {2009, title = {Stratos: a code for 3D free surface flows with floating constraints}, number = {SISSA;41/2009/M}, year = {2009}, abstract = {This report presents a brief discussion of the theoretical aspects and practical implementation of STRATOS . STRATOS is a 3D code for the simulation\\nof hydrodynamic flows for incompressible fluids, in the presence of a free surface, capable of simulating the interaction between the free surface and a\\nfloating object via Lagrange multipliers......}, url = {http://hdl.handle.net/1963/3701}, author = {Antonio DeSimone and B. Bianchi and Luca Heltai} } @article {2009, title = {Tools for the Solution of PDEs Defined on Curved Manifolds with deal.II}, number = {SISSA;42/2009/M}, year = {2009}, abstract = {The deal.II finite element library was originally designed to solve partial differential equations defined on one, two or three space dimensions, mostly\\nvia the Finite Element Method. In its versions prior to version 6.2, the user could not solve problems defined on curved manifolds embedded in two or\\nthree spacial dimensions. This infrastructure is needed if one wants to solve, for example, Boundary Integral Equations.}, url = {http://hdl.handle.net/1963/3700}, author = {Antonio DeSimone and Luca Heltai and Cataldo Manigrasso} } @article {2009, title = {On universality of critical behaviour in the focusing nonlinear Schr{\"o}dinger equation, elliptic umbilic catastrophe and the {\\\\it tritronqu{\'e}e} solution to the Painlev{\'e}-I equation}, journal = {J. Nonlinear Sci. 19 (2009) 57-94}, number = {arXiv.org;0704.0501}, year = {2009}, abstract = {We argue that the critical behaviour near the point of {\textquoteleft}{\textquoteleft}gradient catastrophe\\\" of the solution to the Cauchy problem for the focusing nonlinear Schr\\\\\\\"odinger equation $ i\\\\epsilon \\\\psi_t +\\\\frac{\\\\epsilon^2}2\\\\psi_{xx}+ |\\\\psi|^2 \\\\psi =0$ with analytic initial data of the form $\\\\psi(x,0;\\\\epsilon) =A(x) e^{\\\\frac{i}{\\\\epsilon} S(x)}$ is approximately described by a particular solution to the Painlev\\\\\\\'e-I equation.}, doi = {10.1007/s00332-008-9025-y}, url = {http://hdl.handle.net/1963/2525}, author = {Boris Dubrovin and Tamara Grava and Christian Klein} } @article {2009, title = {A variational model for quasistatic crack growth in nonlinear elasticity: some qualitative properties of the solutions}, journal = {Boll. Unione Mat. Ital. (9) 2 (2009) 371-390}, number = {SISSA;41/2008/M}, year = {2009}, url = {http://hdl.handle.net/1963/2675}, author = {Gianni Dal Maso and Alessandro Giacomini and Marcello Ponsiglione} } @article {2008, title = {Decomposition results for functions with bounded variation}, journal = {Boll. Unione Mat. Ital. (9) 1 (2008) 497-505}, year = {2008}, publisher = {Unione Matematica Italiana}, url = {http://hdl.handle.net/1963/3535}, author = {Gianni Dal Maso and Rodica Toader} } @article {2008, title = {Eulerian calculus for the displacement convexity in the Wasserstein distance}, journal = {SIAM J. Math. Anal. 40 (2008) 1104-1122}, number = {arXiv.org;0801.2455v1}, year = {2008}, publisher = {SIAM}, abstract = {In this paper we give a new proof of the (strong) displacement convexity of a class of integral functionals defined on a compact Riemannian manifold satisfying a lower Ricci curvature bound. Our approach does not rely on existence and regularity results for optimal transport maps on Riemannian manifolds, but it is based on the Eulerian point of view recently introduced by Otto and Westdickenberg [SIAM J. Math. Anal., 37 (2005), pp. 1227-1255] and on the metric characterization of the gradient flows generated by the functionals in the Wasserstein space.}, doi = {10.1137/08071346X}, url = {http://hdl.handle.net/1963/3413}, author = {Sara Daneri and Giuseppe Savar{\`e}} } @article {2008, title = {Existence of conformal metrics with constant $Q$-curvature}, journal = {Ann. of Math. 168 (2008) 813-858}, number = {SISSA;70/2004/M}, year = {2008}, abstract = {Given a compact four dimensional manifold, we prove existence of conformal metrics with constant $Q$-curvature under generic assumptions. The problem amounts to solving a fourth-order nonlinear elliptic equation with variational structure. Since the corresponding Euler functional is in general unbounded from above and from below, we employ topological methods and minimax schemes, jointly with a compactness result by the second author.}, url = {http://hdl.handle.net/1963/2308}, author = {Zindine Djadli and Andrea Malchiodi} } @article {2008, title = {Frobenius Manifolds and Central Invariants for the Drinfeld - Sokolov Bihamiltonian Structures}, journal = {Adv. Math. 219 (2008) 780-837}, number = {arXiv.org;0710.3115}, year = {2008}, abstract = {The Drinfeld - Sokolov construction associates a hierarchy of bihamiltonian integrable systems with every untwisted affine Lie algebra. We compute the complete set of invariants of the related bihamiltonian structures with respect to the group of Miura type transformations.}, doi = {10.1016/j.aim.2008.06.009}, url = {http://hdl.handle.net/1963/2523}, author = {Boris Dubrovin and Liu Si-Qi and Zhang Youjin} } @article {2008, title = {Globally stable quasistatic evolution in plasticity with softening}, journal = {Netw. Heterog. Media 3 (2008) 567-614}, number = {SISSA;23/2007/M}, year = {2008}, abstract = {We study a relaxed formulation of the quasistatic evolution problem in the context of small strain associative elastoplasticity with softening. The relaxation takes place in spaces of generalized Young measures. The notion of solution is characterized by the following properties: global stability at each time and energy balance on each\\ntime interval. An example developed in detail compares the solutions obtained by this method with the ones provided by a vanishing viscosity approximation, and shows that only the latter capture a decreasing branch in the stress-strain response.}, url = {http://hdl.handle.net/1963/1965}, author = {Gianni Dal Maso and Antonio DeSimone and Maria Giovanna Mora and Massimiliano Morini} } @article {2008, title = {Gradient bounds for minimizers of free discontinuity problems related to cohesive zone models in fracture mechanics}, journal = {Calc. Var. Partial Differential Equations 31 (2008) 137-145}, number = {SISSA;50/2005/M}, year = {2008}, abstract = {In this note we consider a free discontinuity problem for a scalar function, whose energy depends also on the size of the jump. We prove that the gradient of every smooth local minimizer never exceeds a constant, determined only by the data of the problem.}, doi = {10.1007/s00526-006-0084-3}, url = {http://hdl.handle.net/1963/1723}, author = {Gianni Dal Maso and Adriana Garroni} } @article {2008, title = {Hamiltonian partial differential equations and Frobenius manifolds}, journal = {Russian Mathematical Surveys. Volume 63, Issue 6, 2008, Pages 999-1010}, year = {2008}, publisher = {SISSA}, abstract = {In the first part of this paper the theory of Frobenius manifolds\\r\\nis applied to the problem of classification of Hamiltonian systems of partial\\r\\ndifferential equations depending on a small parameter. Also developed is\\r\\na deformation theory of integrable hierarchies including the subclass of\\r\\nintegrable hierarchies of topological type. Many well-known examples\\r\\nof integrable hierarchies, such as the Korteweg{\textendash}de Vries, non-linear\\r\\nSchr{\textasciidieresis}odinger, Toda, Boussinesq equations, and so on, belong to this\\r\\nsubclass that also contains new integrable hierarchies. Some of these new\\r\\nintegrable hierarchies may be important for applications. Properties of the\\r\\nsolutions to these equations are studied in the second part. Consideration\\r\\nis given to the comparative study of the local properties of perturbed and\\r\\nunperturbed solutions near a point of gradient catastrophe. A Universality\\r\\nConjecture is formulated describing the various types of critical behaviour\\r\\nof solutions to perturbed Hamiltonian systems near the point of gradient\\r\\ncatastrophe of the unperturbed solution.}, doi = {10.1070/RM2008v063n06ABEH004575}, url = {http://hdl.handle.net/1963/6471}, author = {Boris Dubrovin} } @article {2008, title = {The Isospectral Dirac Operator on the 4-dimensional Orthogonal Quantum Sphere}, journal = {Comm. Math. Phys. 279 (2008) 77-116}, number = {SISSA;95/2007/MP}, year = {2008}, abstract = {Equivariance under the action of Uq(so(5)) is used to compute the left regular and (chiral) spinorial representations of the algebra of the quantum Euclidean 4-sphere S^4_q. These representations are the constituents of a spectral triple on this sphere with a Dirac operator which is isospectral to the canonical one of the spin structure of the round undeformed four-sphere and which gives metric dimension four for the noncommutative geometry. Non-triviality of the geometry is proved by pairing the associated Fredholm module with an {\textquoteleft}instanton\\\' projection. A real structure which satisfies all required properties modulo a suitable ideal of {\textquoteleft}infinitesimals\\\' is also introduced.}, doi = {10.1007/s00220-008-0420-x}, url = {http://hdl.handle.net/1963/2567}, author = {Francesco D{\textquoteright}Andrea and Ludwik Dabrowski and Giovanni Landi} } @article {2008, title = {The Noncommutative Geometry of the Quantum Projective Plane}, journal = {Rev. Math. Phys. 20 (2008) 979-1006}, number = {SISSA;100/2007/MP}, year = {2008}, abstract = {We study the spectral geometry of the quantum projective plane CP^2_q. In particular, we construct a Dirac operator which gives a 0^+ summable triple, equivariant under U_q(su(3)).}, doi = {10.1142/S0129055X08003493}, url = {http://hdl.handle.net/1963/2548}, author = {Francesco D{\textquoteright}Andrea and Ludwik Dabrowski and Giovanni Landi} } @article {2008, title = {Optimal Strokes for Low Reynolds Number Swimmers: An Example}, journal = {J. Nonlinear Sci. 18 (2008) 277-302}, year = {2008}, publisher = {Springer}, abstract = {Swimming, i.e., being able to advance in the absence of external forces by performing cyclic shape changes, is particularly demanding at low Reynolds numbers. This is the regime of interest for micro-organisms and micro- or nano-robots. We focus in this paper on a simple yet representative example: the three-sphere swimmer of Najafi and Golestanian (Phys. Rev. E, 69, 062901-062904, 2004). For this system, we show how to cast the problem of swimming in the language of control theory, prove global controllability (which implies that the three-sphere swimmer can indeed swim), and propose a numerical algorithm to compute optimal strokes (which turn out to be suitably defined sub-Riemannian geodesics).}, doi = {10.1007/s00332-007-9013-7}, url = {http://hdl.handle.net/1963/4006}, author = {Fran{\c c}ois Alouges and Antonio DeSimone and Aline Lefebvre} } @article {2008, title = {Relaxation of some transversally isotropic energies and applications to smectic A elastomers}, journal = {Math. Models Methods Appl. Sci. 18 (2008) 1-20}, number = {SISSA;01/2007/M}, year = {2008}, doi = {10.1142/S0218202508002693}, url = {http://hdl.handle.net/1963/1912}, author = {James Adams and Sergio Conti and Antonio DeSimone and Georg Dolzmann} } @article {2008, title = {A vanishing viscosity approach to quasistatic evolution in plasticity with softening}, journal = {Arch. Ration. Mech. Anal. 189 (2008) 469-544}, number = {SISSA;38/2006/M}, year = {2008}, abstract = {We deal with quasistatic evolution problems in plasticity with softening, in the framework of small strain associative elastoplasticity. The presence of a nonconvex term due to the softening phenomenon requires a nontrivial extension of the variational framework for rate-independent problems to the case of a nonconvex energy functional. We argue that, in this case, the use of global minimizers in the corresponding incremental problems is not justified from the mechanical point of view. Thus, we analize a different selection criterion for the solutions of the quasistatic evolution problem, based on a viscous approximation. This leads to a generalized formulation in terms of Young measures, developed in the first part of the paper. In the second part we apply our approach to some concrete examples.}, doi = {10.1007/s00205-008-0117-5}, url = {http://hdl.handle.net/1963/1844}, author = {Gianni Dal Maso and Antonio DeSimone and Maria Giovanna Mora and Massimiliano Morini} } @article {2007, title = {Canonical structure and symmetries of the Schlesinger equations}, journal = {Comm. Math. Phys. 271 (2007) 289-373}, number = {arXiv.org;math/0311261v4}, year = {2007}, abstract = {The Schlesinger equations S (n,m) describe monodromy preserving deformations of order m Fuchsian systems with n+1 poles. They can be considered as a family of commuting time-dependent Hamiltonian systems on the direct product of n copies of m{\texttimes}m matrix algebras equipped with the standard linear Poisson bracket. In this paper we present a new canonical Hamiltonian formulation ofthe general Schlesinger equations S (n,m) for all n, m and we compute the action of the symmetries of the Schlesinger equations in these coordinates.}, doi = {10.1007/s00220-006-0165-3}, url = {http://hdl.handle.net/1963/1997}, author = {Boris Dubrovin and Marta Mazzocco} } @article {2007, title = {The complete one-loop spin chain for N=2 Super-Yang-Mills}, number = {SISSA;99/2004/FM}, year = {2007}, note = {Contributed to NATO Advanced Study Institute and EC Summer School on String Theory: From Gauge Interactions to Cosmology, Cargese, France, 7-19 Jun 2004.}, abstract = {We show that the complete planar one-loop mixing matrix of the N=2 Super Yang--Mills theory can be obtained from a reduction of that of the N=4 theory. For composite operators of scalar fields, this yields an anisotropic XXZ spin chain, whose spectrum of excitations displays a mass gap.}, url = {http://hdl.handle.net/1963/2309}, author = {Paolo Di Vecchia and Alessandro Tanzini} } @article {2007, title = {Critical voltages and blocking stresses in nematic gels}, journal = {Eur. Phys. J. E 24 (2007) 303-310}, number = {SISSA;31/2007/M}, year = {2007}, abstract = {We use a recently proposed model to study the dynamics of director remodeling in nematic gels under combined electro-mechanical loading. Focusing on a model specimen, we describe the critical volt-ages that must be exceeded to achieve mesogen reorientation, and the blocking stresses that prevent alignment of the nematic mesogens with the electric field. The corresponding phase diagram shows that the dynamic thresholds defined above are different from those predicted on the sole basis of energetics. Multistep loading programs are used to explore the energy landscape of our model specimen, showing the existence of multiple local minima under the same voltage and applied stress. This leads us to conclude that hysteresis should be expected in the electro-mechanical response of nematic gels.}, doi = {10.1140/epje/i2007-10240-2}, url = {http://hdl.handle.net/1963/2553}, author = {Antonio DeSimone and Antonio Di Carlo and Luciano Teresi} } @article {2007, title = {Dirac operators on all Podles quantum spheres}, journal = {J. Noncomm. Geom. 1 (2007) 213-239}, number = {arXiv.org;math/0606480v2}, year = {2007}, abstract = {We construct spectral triples on all Podles quantum spheres. These noncommutative geometries are equivariant for a left action of $U_q(su(2))$ and are regular, even and of metric dimension 2. They are all isospectral to the undeformed round geometry of the 2-sphere. There is also an equivariant real structure for which both the commutant property and the first order condition for the Dirac operators are valid up to infinitesimals of arbitrary order.}, doi = {10.4171/JNCG/5}, url = {http://hdl.handle.net/1963/2177}, author = {Francesco D{\textquoteright}Andrea and Ludwik Dabrowski and Giovanni Landi and Elmar Wagner} } @article {2007, title = {A new model for contact angle hysteresis}, number = {SISSA;37/2006/M}, year = {2007}, abstract = {We present a model which explains several experimental observations relating contact angle hysteresis with surface roughness. The model is based on the balance between released energy and dissipation, and it describes the stick-slip behavior of drops on a rough surface using ideas similar to those employed in dry friction, elasto-plasticity and fracture mechanics. The main results of our analysis are formulas giving the interval of stable contact angles as a function of the surface roughness. These formulas show that the difference between advancing and receding angles is much larger for a drop in complete contact with the substrate (Wenzel drop) than for one whose cavities are filled with air (Cassie-Baxter drop). This fact is used as the key tool to interpret the experimental evidence.}, url = {http://hdl.handle.net/1963/1848}, author = {Antonio DeSimone and Natalie Gruenewald and Felix Otto} } @mastersthesis {2007, title = {Noncommutative geometry and quantum group symmetries}, year = {2007}, school = {SISSA}, abstract = {It is a widespread belief that mathematics originates from the desire to understand (and eventually to formalize) some aspects of the real world. Quoting [Man07], {\guillemotleft}we are doing mathematics in order to understand, create, and handle things, and perhaps this understanding is mathematics{\guillemotright} . Let me thus begin with a brief discussion of the physical ideas that motivated the development of Noncommutative Geometry and Quantum Group Theory - the areas of mathematics to which this dissertation belongs. Some physicists believe, and Einstein himself expressed this view in [Ein98a], that physics progresses in stages: there is no {\textquoteleft}final\\\' theory of Nature, but simply a sequence of theories which provide more and more accurate descriptions of the real world...}, keywords = {Noncommutative geometry}, url = {http://hdl.handle.net/1963/5269}, author = {Francesco D{\textquoteright}Andrea} } @article {2007, title = {On a notion of unilateral slope for the Mumford-Shah functional}, journal = {NoDEA 13 (2007) 713-734}, number = {SISSA;78/2004/M}, year = {2007}, abstract = {In this paper we introduce a notion of unilateral slope for the Mumford-Shah functional, and provide an explicit formula in the case of smooth cracks. We show that the slope is not lower semicontinuous and study the corresponding relaxed functional.}, doi = {10.1007/s00030-006-4054-4}, url = {http://hdl.handle.net/1963/2059}, author = {Gianni Dal Maso and Rodica Toader} } @article {2007, title = {The number of eigenvalues of three-particle Schr{\"o}dinger operators on lattices}, journal = {J. Phys. A 40 (2007) 14819-14842}, number = {arXiv.org;math/0703191v1}, year = {2007}, abstract = {We consider the Hamiltonian of a system of three quantum mechanical particles (two identical fermions and boson)on the three-dimensional lattice $\\\\Z^3$ and interacting by means of zero-range attractive potentials. We describe the location and structure of the essential spectrum of the three-particle discrete Schr\\\\\\\"{o}dinger operator $H_{\\\\gamma}(K),$ $K$ being the total quasi-momentum and $\\\\gamma>0$ the ratio of the mass of fermion and boson.\\nWe choose for $\\\\gamma>0$ the interaction $v(\\\\gamma)$ in such a way the system consisting of one fermion and one boson has a zero energy resonance.\\nWe prove for any $\\\\gamma> 0$ the existence infinitely many eigenvalues of the operator $H_{\\\\gamma}(0).$ We establish for the number $N(0,\\\\gamma; z;)$ of eigenvalues lying below $z<0$ the following asymptotics $$ \\\\lim_{z\\\\to 0-}\\\\frac{N(0,\\\\gamma;z)}{\\\\mid \\\\log \\\\mid z\\\\mid \\\\mid}={U} (\\\\gamma) .$$ Moreover, for all nonzero values of the quasi-momentum $K \\\\in T^3 $ we establish the finiteness of the number $ N(K,\\\\gamma;\\\\tau_{ess}(K))$ of eigenvalues of $H(K)$ below the bottom of the essential spectrum and we give an asymptotics for the number $N(K,\\\\gamma;0)$ of eigenvalues below zero.}, doi = {10.1088/1751-8113/40/49/015}, url = {http://hdl.handle.net/1963/2576}, author = {Sergio Albeverio and Gianfausto Dell{\textquoteright}Antonio and Saidakhmat N. Lakaev} } @article {2007, title = {Quasistatic crack growth for a cohesive zone model with prescribed crack path}, number = {SISSA;44/2005/M}, year = {2007}, abstract = {In this paper we study the quasistatic crack growth for a cohesive zone model. We assume that the crack path is prescribed and we study the time evolution of the crack in the framework of the variational theory of rate-independent processes.}, doi = {10.1017/S030821050500079X}, url = {http://hdl.handle.net/1963/1686}, author = {Gianni Dal Maso and Chiara Zanini} } @article {2007, title = {Quasistatic evolution problems for pressure-sensitive plastic materials}, journal = {Milan J. Math. 75 (2007) 117-134}, number = {SISSA;27/2007/M}, year = {2007}, abstract = {We study quasistatic evolution problems for pressure-sensitive plastic materials in the context of small strain associative perfect plasticity.}, doi = {10.1007/s00032-007-0071-y}, url = {http://hdl.handle.net/1963/1962}, author = {Gianni Dal Maso and Alexey Demyanov and Antonio DeSimone} } @article {2007, title = {On the reductions and classical solutions of the Schlesinger equations}, journal = {Differential equations and quantum groups, IRMA Lect. Math. Theor. Phys. 9 (2007) 157-187}, year = {2007}, publisher = {SISSA}, abstract = {The Schlesinger equations S(n,m) describe monodromy preserving\\r\\ndeformations of order m Fuchsian systems with n+1 poles. They\\r\\ncan be considered as a family of commuting time-dependent Hamiltonian\\r\\nsystems on the direct product of n copies of m{\texttimes}m matrix algebras\\r\\nequipped with the standard linear Poisson bracket. In this paper we address\\r\\nthe problem of reduction of particular solutions of {\textquotedblleft}more complicated{\textquotedblright}\\r\\nSchlesinger equations S(n,m) to {\textquotedblleft}simpler{\textquotedblright} S(n',m') having n' < n\\r\\nor m' < m.}, url = {http://hdl.handle.net/1963/6472}, author = {Boris Dubrovin and Marta Mazzocco} } @article {2007, title = {Soft elasticity and microstructure in smectic C elastomers}, number = {SISSA;05/2006/M}, year = {2007}, abstract = {Smectic C elastomers are layered materials exhibiting a solid-like elastic response along the layer normal and a rubbery one in the plane. The set of strains minimizing the elastic energy contains a one-parameter family of simple stretches associated with an internal degree of freedom, coming from the in-plane component of the director. We investigate soft elasticity and the corresponding microstructure by determining the quasiconvex hull of the set , and use this to propose experimental tests that should make the predicted soft response observable.}, doi = {10.1007/s00161-006-0031-8}, url = {http://hdl.handle.net/1963/1811}, author = {Antonio DeSimone and James Adams and Sergio Conti} } @article {2007, title = {Stability of front tracking solutions to the initial and boundary value problem for systems of conservation laws}, journal = {NoDEA Nonlinear Differential Equations Appl. 14 (2007) 569-592}, number = {SISSA;68/2005/M}, year = {2007}, doi = {10.1007/s00030-007-5010-7}, url = {http://hdl.handle.net/1963/1769}, author = {Andrea Marson and Carlotta Donadello} } @article {2007, title = {Time-dependent systems of generalized Young measures}, number = {SISSA;98/2005/M}, year = {2007}, abstract = {In this paper some new tools for the study of evolution problems in the framework of Young measures are introduced. A suitable notion of time-dependent system of generalized Young measures is defined, which allows to extend the classical notions of total variation and absolute continuity with respect to time, as well as the notion of time derivative. The main results are a Helly type theorem for sequences of systems of generalized Young measures and a theorem about the existence of the time derivative for systems with bounded variation with respect to time.}, url = {http://hdl.handle.net/1963/1795}, author = {Gianni Dal Maso and Antonio DeSimone and Maria Giovanna Mora and Massimiliano Morini} } @article {2006, title = {2-d stability of the N{\'e}el wall}, journal = {Calc. Var. Partial Differential Equations 27 (2006) 233-253}, year = {2006}, abstract = {We are interested in thin-film samples in micromagnetism, where the magnetization m is a 2-d unit-length vector field. More precisely we are interested in transition layers which connect two opposite magnetizations, so called N{\'e}el walls.}, doi = {10.1007/s00526-006-0019-z}, url = {http://hdl.handle.net/1963/2194}, author = {Antonio DeSimone and Hans Knuepfer and Felix Otto} } @article {2006, title = {A Canonical Frame for Nonholonomic Rank Two Distributions of Maximal Class}, number = {SISSA;25/2005/M}, year = {2006}, abstract = {In 1910 E. Cartan constructed the canonical frame and found the most symmetric case for maximally nonholonomic rank 2 distributions in R5. We solve the analogous problems for rank 2 distributions in Rn for arbitrary n > 5. Our method is a kind of symplectification of the problem and it is completely different from the Cartan method of equivalence.}, doi = {10.1016/j.crma.2006.02.010}, url = {http://hdl.handle.net/1963/1712}, author = {Boris Doubrov and Igor Zelenko} } @article {2006, title = {A cyclic integral on k-Minkowski noncommutative space-time}, journal = {Int. J. Mod. Phys. A 21 (2006) 3133-3150}, number = {arXiv.org;hep-th/0407227v1}, year = {2006}, abstract = {We examine some alternative possibilities for an action functional for $\\\\kappa$-Minkowski noncommutative spacetime, with an approach which should be applicable to other spacetimes with coordinate-dependent commutators of the spacetime coordinates ($[x_\\\\mu,x_\\\\nu]=f_{\\\\mu,\\\\nu}(x)$). Early works on $\\\\kappa$-Minkowski focused on $\\\\kappa$-Poincar\\\\\\\'e covariance and the dependence of the action functional on the choice of Weyl map, renouncing to invariance under cyclic permutations of the factors composing the argument of the action functional. A recent paper (hep-th/0307149), by Dimitrijevic, Jonke, Moller, Tsouchnika, Wess and Wohlgenannt, focused on a specific choice of Weyl map and, setting aside the issue of $\\\\kappa$-Poincar\\\\\\\'e covariance of the action functional, introduced in implicit form a cyclicity-inducing measure. We provide an explicit formula for (and derivation of) a choice of measure which indeed ensures cyclicity of the action functional, and we show that the same choice of measure is applicable to all the most used choices of Weyl map. We find that this {\textquoteleft}{\textquoteleft}cyclicity-inducing measure\\\'\\\' is not covariant under $\\\\kappa$-Poincar\\\\\\\'e transformations. We also notice that the cyclicity-inducing measure can be straightforwardly derived using a map which connects the $\\\\kappa$-Minkowski spacetime coordinates and the spacetime coordinates of a {\textquoteleft}{\textquoteleft}canonical\\\'\\\' noncommutative spacetime, with coordinate-independent commutators.}, doi = {10.1142/S0217751X06031077}, url = {http://hdl.handle.net/1963/2158}, author = {Alessandra Agostini and Giovanni Amelino-Camelia and Michele Arzano and Francesco D{\textquoteright}Andrea} } @article {2006, title = {Extended affine Weyl groups and Frobenius manifolds -- II}, number = {SISSA;90/2005/FM}, year = {2006}, abstract = {For the root system of type $B_l$ and $C_l$, we generalize the result of \\\\cite{DZ1998} by showing the existence of a Frobenius manifold structure on the orbit space of the extended affine Weyl group that corresponds to any vertex of the Dynkin diagram instead of a particular choice of \\\\cite{DZ1998}.}, url = {http://hdl.handle.net/1963/1787}, author = {Boris Dubrovin and Zhang Youjin and Zuo Dafeng} } @article {2006, title = {On Hamiltonian perturbations of hyperbolic systems of conservation laws, II: universality of critical behaviour}, number = {SISSA;89/2005/FM}, year = {2006}, abstract = {Hamiltonian perturbations of the simplest hyperbolic equation $u_t + a(u) u_x=0$ are studied. We argue that the behaviour of solutions to the perturbed equation near the point of gradient catastrophe of the unperturbed one should be essentially independent on the choice of generic perturbation neither on the choice of generic solution. Moreover, this behaviour is described by a special solution to an integrable fourth order ODE.}, doi = {10.1007/s00220-006-0021-5}, url = {http://hdl.handle.net/1963/1786}, author = {Boris Dubrovin} } @article {2006, title = {On Hamiltonian perturbations of hyperbolic systems of conservation laws I: quasitriviality of bihamiltonian perturbations}, journal = {Comm. Pure Appl. Math. 59 (2006) 559-615}, number = {arXiv.org;math/0410027}, year = {2006}, abstract = {We study the general structure of formal perturbative solutions to the Hamiltonian perturbations of spatially one-dimensional systems of hyperbolic PDEs. Under certain genericity assumptions it is proved that any bihamiltonian perturbation can be eliminated in all orders of the perturbative expansion by a change of coordinates on the infinite jet space depending rationally on the derivatives. The main tools is in constructing of the so-called quasi-Miura transformation of jet coordinates eliminating an arbitrary deformation of a semisimple bihamiltonian structure of hydrodynamic type (the quasitriviality theorem). We also describe, following \\\\cite{LZ1}, the invariants of such bihamiltonian structures with respect to the group of Miura-type transformations depending polynomially on the derivatives.}, doi = {10.1002/cpa.20111}, url = {http://hdl.handle.net/1963/2535}, author = {Boris Dubrovin and Liu Si-Qi and Zhang Youjin} } @article {2006, title = {Local Index Formula on the Equatorial Podles Sphere}, number = {SISSA;85/2005/FM}, year = {2006}, abstract = {We discuss spectral properties of the equatorial Podles sphere. As a preparation we also study the {\textquoteleft}degenerate\\\' (i.e. $q=0$) case (related to the quantum disk). We consider two different spectral triples: one related to the Fock representation of the Toeplitz algebra and the isopectral one....}, doi = {10.1007/s11005-005-0047-1}, url = {http://hdl.handle.net/1963/1782}, author = {Francesco D{\textquoteright}Andrea and Ludwik Dabrowski} } @article {2006, title = {Quasistatic evolution problems for linearly elastic-perfectly plastic materials}, journal = {Arch. Ration. Mech. Anal. 180 (2006) 237-291}, number = {arXiv.org;math/0412212v1}, year = {2006}, abstract = {The problem of quasistatic evolution in small strain associative elastoplasticity is studied in the framework of the variational theory for rate-independent processes. Existence of solutions is proved through the use of incremental variational problems in spaces of functions with bounded deformation. This provides a new approximation result for the solutions of the quasistatic evolution problem, which are shown to be absolutely continuous in time. Four equivalent formulations of the problem in rate form are derived. A strong formulation of the flow rule is obtained by introducing a precise definition of the stress on the singular set of the plastic strain.}, doi = {10.1007/s00205-005-0407-0}, url = {http://hdl.handle.net/1963/2129}, author = {Gianni Dal Maso and Antonio DeSimone and Maria Giovanna Mora} } @inbook {2006, title = {Recent analytical developments in micromagnetics}, booktitle = {The science of hysteresis / eds. Giorgio Bertotti, Isaak D. Mayergoyz. - Amsterdam: Elsevier, 2006. Vol.2, 269-381.}, number = {SISSA;76/2004/M}, year = {2006}, isbn = {978-0-12-480874-4}, url = {http://hdl.handle.net/1963/2230}, author = {Antonio DeSimone and Robert V. Kohn and Stefan M{\"u}ller and Felix Otto} } @article {2006, title = {Spectral geometry of k-Minkowski space}, journal = {J. Math. Phys. 47 (2006) 062105}, number = {arXiv.org;hep-th/0503012v4}, year = {2006}, abstract = {After recalling Snyder{\textquoteright}s idea of using vector fields over a smooth manifold as "coordinates on a noncommutative space", we discuss a two dimensional toy-model whose "dual" noncommutative coordinates form a Lie algebra: this is the well known $\kappa$-Minkowski space. We show how to improve Snyder{\textquoteright}s idea using the tools of quantum groups and noncommutative geometry. We find a natural representation of the coordinate algebra of $\kappa$-Minkowski as linear operators on an Hilbert space study its "spectral properties" and discuss how to obtain a Dirac operator for this space. We describe two Dirac operators. The first is associated with a spectral triple. We prove that the cyclic integral of M. Dimitrijevic et al. can be obtained as Dixmier trace associated to this triple. The second Dirac operator is equivariant for the action of the quantum Euclidean group, but it has unbounded commutators with the algebra.

}, doi = {10.1063/1.2204808}, url = {http://hdl.handle.net/1963/2131}, author = {Francesco D{\textquoteright}Andrea} } @inbook {2006, title = {On universality of critical behaviour in Hamiltonian PDEs}, booktitle = {Geometry, topology, and mathematical physics : S.P. Novikov\\\'s seminar : 2006-2007 / V.M. Buchstaber, I.M. Krichever, editors. - Providence, R.I. : American Mathematical Society, 2008. - pages : 59-109}, number = {American Mathematical Society translations, ISSN 0065-9290;ser. 2;v. 224}, year = {2006}, publisher = {American Mathematical Society}, organization = {American Mathematical Society}, abstract = {Our main goal is the comparative study of singularities of solutions to\\r\\nthe systems of rst order quasilinear PDEs and their perturbations containing higher\\r\\nderivatives. The study is focused on the subclass of Hamiltonian PDEs with one\\r\\nspatial dimension. For the systems of order one or two we describe the local structure\\r\\nof singularities of a generic solution to the unperturbed system near the point of\\r\\n\\\\gradient catastrophe\\\" in terms of standard objects of the classical singularity theory;\\r\\nwe argue that their perturbed companions must be given by certain special solutions\\r\\nof Painlev e equations and their generalizations.}, isbn = {978-0-8218-4674-2}, url = {http://hdl.handle.net/1963/6491}, author = {Boris Dubrovin} } @article {2006, title = {Variational problems in fracture mechanics}, number = {SISSA;10/2006/M}, year = {2006}, abstract = {We present some recent existence results for the variational model of crack growth in brittle materials proposed by Francfort and Marigo in 1998. These results, obtained in collaboration with Francfort and Toader, cover the case of arbitrary space dimension with a general quasiconvex bulk energy and with prescribed boundary deformations and applied loads.}, url = {http://hdl.handle.net/1963/1816}, author = {Gianni Dal Maso} } @inbook {2006, title = {WDVV equations and Frobenius manifolds}, booktitle = {Encyclopedia of Mathematical Physics. Vol 1 A : A-C. Oxford: Elsevier, 2006, p. 438-447}, year = {2006}, publisher = {SISSA}, organization = {SISSA}, isbn = {0125126611}, url = {http://hdl.handle.net/1963/6473}, author = {Boris Dubrovin} } @article {2005, title = {Decay of a bound state under a time-periodic perturbation: a toy case}, journal = {J. Phys. A 38 (2005) 4769-4781}, number = {SISSA;54/2004/FM}, year = {2005}, abstract = {We study the time evolution of a three dimensional quantum particle, initially in a bound state, under the action of a time-periodic zero range interaction with {\textquoteleft}{\textquoteleft}strength\\\'\\\' (\\\\alpha(t)). Under very weak generic conditions on the Fourier coefficients of (\\\\alpha(t)), we prove complete ionization as (t \\\\to \\\\infty). We prove also that, under the same conditions, all the states of the system are scattering states.}, doi = {10.1088/0305-4470/38/22/002}, url = {http://hdl.handle.net/1963/2298}, author = {Michele Correggi and Gianfausto Dell{\textquoteright}Antonio} } @article {2005, title = {The Dirac operator on SU_q(2)}, journal = {Commun. Math. Phys. 259 (2005) 729-759}, number = {arXiv:math/0411609;}, year = {2005}, note = {v2: minor changes}, publisher = {Springer}, abstract = {We construct a 3^+ summable spectral triple (A(SU_q(2)),H,D) over the quantum group SU_q(2) which is equivariant with respect to a left and a right action of U_q(su(2)). The geometry is isospectral to the classical case since the spectrum of the operator D is the same as that of the usual Dirac operator on the 3-dimensional round sphere. The presence of an equivariant real structure J demands a modification in the axiomatic framework of spectral geometry, whereby the commutant and first-order properties need be satisfied only modulo infinitesimals of arbitrary high order.}, doi = {10.1007/s00220-005-1383-9}, url = {http://hdl.handle.net/1963/4425}, author = {Ludwik Dabrowski and Giovanni Landi and Andrzej Sitarz and Walter van Suijlekom and Joseph C. Varilly} } @article {2005, title = {A fourth order uniformization theorem on some four manifolds with large total Q-curvature}, journal = {C. R. Acad. Sci. Paris, Ser. I 340 (2005) 341-346.}, year = {2005}, publisher = {Elsevier}, abstract = {Given a four-dimensional manifold (M,g), we study the existence of a conformal metric for which the Q-curvature, associated to a conformally invariant fourth-order operator (the Paneitz operator), is constant. Using a topological argument, we obtain a new result in cases which were still open.}, doi = {10.1016/j.crma.2005.01.013}, url = {http://hdl.handle.net/1963/4868}, author = {Zindine Djadli and Andrea Malchiodi} } @article {2005, title = {Ionization for Three Dimensional Time-dependent Point Interactions}, journal = {Comm. Math. Phys. 257 (2005) 169-192}, number = {SISSA;11/2004/FM}, year = {2005}, abstract = {We study the time evolution of a three dimensional quantum particle under the action of a time-dependent point interaction fixed at the origin. We assume that the {\textquoteleft}{\textquoteleft}strength\\\'\\\' of the interaction (\\\\alpha(t)) is a periodic function with an arbitrary mean. Under very weak conditions on the Fourier coefficients of (\\\\alpha(t)), we prove that there is complete ionization as (t \\\\to \\\\infty), starting from a bound state at time (t = 0). Moreover we prove also that, under the same conditions, all the states of the system are scattering states.}, doi = {10.1007/s00220-005-1293-x}, url = {http://hdl.handle.net/1963/2297}, author = {Michele Correggi and Gianfausto Dell{\textquoteright}Antonio and Rodolfo Figari and Andrea Mantile} } @article {2005, title = {The local index formula for SUq(2)}, journal = {K-Theory 35 (2005) 375-394}, number = {SISSA;01/2005/FM}, year = {2005}, abstract = {We discuss the local index formula of Connes-Moscovici for the isospectral noncommutative geometry that we have recently constructed on quantum SU(2). We work out the cosphere bundle and the dimension spectrum as well as the local cyclic cocycles yielding the index formula.}, doi = {10.1007/s10977-005-3116-4}, url = {http://hdl.handle.net/1963/1713}, author = {Walter van Suijlekom and Ludwik Dabrowski and Giovanni Landi and Andrzej Sitarz and Joseph C. Varilly} } @article {2005, title = {Quasistatic Crack Growth in Nonlinear Elasticity}, journal = {Arch. Ration. Mech. Anal. 176 (2005) 165-225}, number = {SISSA;2/2004/M}, year = {2005}, abstract = {In this paper, we prove a new existence result for a variational model of crack growth in brittle materials proposed in [15]. We consider the case of $n$-dimensional finite elasticity, for an arbitrary $n\\\\ge1$, with a quasiconvex bulk energy and with prescribed boundary deformations and applied loads, both depending on time.}, doi = {10.1007/s00205-004-0351-4}, url = {http://hdl.handle.net/1963/2293}, author = {Gianni Dal Maso and Gilles A. Francfort and Rodica Toader} } @article {2005, title = {Self-similar folding patterns and energy scaling in compressed elastic sheets}, journal = {Comput. Methods Appl. Mech. Engrg. 194 (2005) 2534-2549}, year = {2005}, publisher = {Elsevier}, abstract = {Thin elastic sheets under isotropic compression, such as for example blisters formed by thin films which debonded from the substrate, can exhibit remarkably complex folding patterns. We discuss the scaling of the elastic energy with respect to the film thickness, and show that in certain regimes the optimal energy scaling can be reached\\nby self-similar folding patterns that refine towards the boundary, in agreement with experimental observations. We then extend the analysis\\nto anisotropic compression, and discuss a simplified scalar model which suggests the presence of a transition between a regime where\\nthe deformation is governed by global properties of the domain and another one where the direction of maximal compression dominates and the scale of the folds is mainly determined by the distance to the boundary in the direction of the folds themselves.}, doi = {10.1016/j.cma.2004.07.044}, url = {http://hdl.handle.net/1963/3000}, author = {Sergio Conti and Antonio DeSimone and Stefan M{\"u}ller} } @booklet {2005, title = {Solutions of Neumann problems in domains with cracks and applications to fracture mechanics}, number = {arXiv.org;math.AP/0105132}, year = {2005}, url = {http://hdl.handle.net/1963/1684}, author = {Gianni Dal Maso} } @article {2005, title = {The spectral geometry of the equatorial Podles sphere}, journal = {C. R. Math. 340 (2005) 819-822}, number = {SISSA;71/2004/FM}, year = {2005}, abstract = {We propose a slight modification of the properties of a spectral geometry a la Connes, which allows for some of the algebraic relations to be satisfied only modulo compact operators. On the equatorial Podles sphere we construct suq2-equivariant Dirac operator and real structure which satisfy these modified properties.}, doi = {10.1016/j.crma.2005.04.003}, url = {http://hdl.handle.net/1963/2275}, author = {Ludwik Dabrowski and Giovanni Landi and Mario Paschke and Andrzej Sitarz} } @article {2005, title = {Stress-dilatancy based modelling of granular materials and extensions to soils with crushable grains}, journal = {Int. J. Numer. Anal. Met. 29 (2005) 73-101}, number = {SISSA;74/2004/M}, year = {2005}, abstract = {Stress-dilatancy relations have played a crucial role in the understanding of the mechanical behaviour of soils and in the development of realistic constitutive models for their response. Recent investigations on the mechanical behaviour of materials with crushable grains have called into question the validity of classical relations such as those used in critical state soil mechanics.\\nIn this paper, a method to construct thermodynamically consistent (isotropic, three-invariant) elasto-plastic models based on a given stress-dilatancy relation is discussed. Extensions to cover the case of granular materials with crushable grains are also presented, based on the interpretation of some classical model parameters (e.g. the stress ratio at critical state) as internal variables that evolve according to suitable hardening laws.}, doi = {10.1002/nag.405}, url = {http://hdl.handle.net/1963/2165}, author = {Antonio DeSimone and Claudio Tamagnini} } @article {2005, title = {Wetting of rough surfaces: a homogenization approach}, journal = {Proc. R. Soc. Lon. Ser. A 461 (2005) 79-97}, number = {SISSA;75/2004/M}, year = {2005}, abstract = {The contact angle of a drop in equilibrium on a solid is strongly affected by the roughness of the surface on which it rests. We study the roughness-induced enhancement of the hydrophobic or hydrophilic properties of a solid surface through homogenization theory. By relying on a variational formulation of the problem, we show that the macroscopic contact angle is associated with the solution of two cell problems, giving the minimal energy per unit macroscopic area for a transition layer between the rough solid surface and a liquid or vapor phase. Our results are valid for both chemically heterogeneous and homogeneous surfaces. In the latter case, a very transparent structure emerges from the variational\\napproach: the classical laws of Wenzel and Cassie-Baxter give bounds for the optimal energy, and configurations of minimal energy are those leading to the smallest macroscopic contact angle in the hydrophobic case, to the largest one in the hydrophilic case.}, doi = {10.1098/rspa.2004.1364}, url = {http://hdl.handle.net/1963/2253}, author = {Antonio DeSimone and Giovanni Alberti} } @article {2004, title = {On almost duality for Frobenius manifolds}, journal = {Amer. Math. Soc. Transl. 212 (2004)\\n75-132.}, number = {arXiv.org;math/0307374}, year = {2004}, abstract = {We present a universal construction of almost duality for Frobenius manifolds. The analytic setup of this construction is described in details for the case of semisimple Frobenius manifolds. We illustrate the general considerations by examples from the singularity theory, mirror symmetry, the theory of Coxeter groups and Shephard groups, from the Seiberg - Witten duality.}, url = {http://hdl.handle.net/1963/2543}, author = {Boris Dubrovin} } @article {2004, title = {On analytic families of invariant tori for PDEs}, journal = {Ast{\'e}risque. Issue 297, 2004, Pages 35-65}, year = {2004}, publisher = {SISSA}, abstract = {We propose to apply a version of the classical Stokes\\r\\nexpansion method to the perturbative construction of invariant tori for\\r\\nPDEs corresponding to solutions quasiperiodic in space and time variables.\\r\\nWe argue that, for integrable PDEs all but finite number of the\\r\\nsmall divisors arising in the perturbative analysis cancel. As an illustrative\\r\\nexample we establish such cancellations for the case of KP equation.\\r\\nIt is proved that, under mild assumptions about decay of the magnitude\\r\\nof the Fourier modes all analytic families of finite-dimensional invariant\\r\\ntori for KP are given by the Krichever construction in terms of thetafunctions\\r\\nof Riemann surfaces. We also present an explicit construction\\r\\nof infinite dimensional real theta-functions and corresponding quasiperiodic\\r\\nsolutions to KP as sums of infinite number of interacting plane\\r\\nwaves.}, url = {http://hdl.handle.net/1963/6474}, author = {Boris Dubrovin} } @article {2004, title = {Asymptotic behaviour and correctors for linear Dirichlet problems with simultaneously varying operators and domains}, journal = {Ann. Inst. H. Poincar{\'e}. Anal. Non Lin{\'e}aire 21 (2004), (4), p. 445-486.}, number = {SISSA;40/2002/M}, year = {2004}, publisher = {SISSA Library}, abstract = {We consider a sequence of Dirichlet problems in varying domains (or, more generally, of relaxed Dirichlet problems involving measures in M_0) for second order linear elliptic operators in divergence form with varying matrices of coefficients. When the matrices H-converge to a matrix A^0, we prove that there exist a subsequence and a measure mu^0 in M_0 such that the limit problem is the relaxed Dirichlet problem corresponding to A^0 and mu^0. We also prove a corrector result which provides an explicit approximation of the solutions in the H^1-norm, and which is obtained by multiplying the corrector for the H-converging matrices by some special test function which depends both on the varying matrices and on the varying domains.}, url = {http://hdl.handle.net/1963/1611}, author = {Gianni Dal Maso and Francois Murat} } @article {2004, title = {Blow-up solutions for the Schr{\"o}dinger equation in dimension three with a concentrated nonlinearity}, journal = {Ann. Inst. H. Poincare Anal. Non Lineaire 21 (2004) 121-137}, year = {2004}, publisher = {Elsevier}, abstract = {We present some results on the blow-up phenomenon for the Schroedinger equation in dimension three with a nonlinear term supported in a fixed point. We find sufficient conditions for the blow up exploiting the moment of inertia of the solution and the uncertainty principle. In the critical case, we discuss the additional symmetry of the equation and construct a family of explicit blow up solutions.}, doi = {10.1016/j.anihpc.2003.01.002}, url = {http://hdl.handle.net/1963/2998}, author = {Riccardo Adami and Gianfausto Dell{\textquoteright}Antonio and Rodolfo Figari and Alessandro Teta} } @article {2004, title = {Coarse-grained models of materials with non-convex free-energy: two case studies}, journal = {Computer methods in applied mechanics and engineering , 193 (2004) 5129-5141}, year = {2004}, publisher = {Elsevier}, abstract = {Bridging across length scales is one of the fundamental challenges in the computational modelling of material systems whose mechanical response is driven by rough energy landscapes. The typical feature of such systems is that of exhibiting fine scale microstructures. Two case studies, namely, nematic elastomers and ferromagnetic shape memory alloys, are presented to illustrate the use of modern techniques from (non-convex) calculus of variations in developing coarse-grained models of microstructure-driven material response.}, doi = {10.1016/j.cma.2003.12.064}, url = {http://hdl.handle.net/1963/4884}, author = {Antonio DeSimone} } @article {2004, title = {Energetics and switching of quasi-uniform states in small ferromagnetic particles}, journal = {M2AN Math. Model. Numer. Anal. 38 (2004) 235-248}, year = {2004}, publisher = {EDP Sciences}, abstract = {We present a numerical algorithm to solve the micromagnetic equations based on tangential-plane minimization for the magnetization update and a homothethic-layer decomposition of outer space for the computation of the demagnetization field. As a first application, detailed results on the flower-vortex transition in the cube of Micromagnetic Standard Problem number 3 are obtained, which confirm, with a different method, those already present in the literature, and validate our method and code. We then turn to switching of small cubic or almost-cubic particles, in the single-domain limit. Our data show systematic deviations from the Stoner-Wohlfarth model due to the non-ellipsoidal shape of the particle, and in particular a non-monotone dependence on the particle size.}, doi = {10.1051/m2an:2004011}, url = {http://hdl.handle.net/1963/2999}, author = {Fran{\c c}ois Alouges and Sergio Conti and Antonio DeSimone and Ivo Pokern} } @article {2004, title = {The Extended Toda Hierarchy}, journal = {Moscow Math. J. 4 (2004)\\n313-332.}, number = {arXiv.org;nlin/0306060}, year = {2004}, url = {http://hdl.handle.net/1963/2542}, author = {Guido Carlet and Boris Dubrovin and Zhang Youjin} } @article {2004, title = {Higher order quasiconvexity reduces to quasiconvexity}, journal = {Arch. Ration. Mech. Anal. 171 (2004) 55-81}, number = {SISSA;41/2003/M}, year = {2004}, publisher = {Springer}, abstract = {In this paper it is shown that higher order quasiconvex functions suitable in the variational treatment of problems involving second derivatives may be extended to the space of all matrices as classical quasiconvex functions. Precisely, it is proved that a smooth strictly 2-quasiconvex function with p-growth at infinity, p>1, is the restriction to symmetric matrices of a 1-quasiconvex function with the same growth. As a consequence, lower semicontinuity results for second-order variational problems are deduced as corollaries of well-known first order theorems.}, doi = {10.1007/s00205-003-0278-1}, url = {http://hdl.handle.net/1963/2911}, author = {Gianni Dal Maso and Irene Fonseca and Giovanni Leoni and Massimiliano Morini} } @article {2004, title = {Quasi-static evolution in brittle fracture: the case of bounded solutions}, journal = {Quad. Mat. Dip. Mat. Seconda Univ. Napoli 14 (2004) 245-266}, number = {SISSA;3/2004/M}, year = {2004}, abstract = {The main steps of the proof of the existence result for the quasi-static evolution of cracks in brittle materials, obtained in [7] in the vector case and for a general quasiconvex elastic energy, are presented here under the simplifying assumption that the minimizing sequences involved in the problem are uniformly bounded in $L^\\\\infty$.}, url = {http://hdl.handle.net/1963/2229}, author = {Gianni Dal Maso and Gilles A. Francfort and Rodica Toader} } @article {2004, title = {Rotating Singular Perturbations of the Laplacian}, journal = {Ann. Henri Poincare 5 (2004) 773-808}, number = {SISSA;66/2003/FM}, year = {2004}, publisher = {Springer}, abstract = {We study a system of a quantum particle interacting with a singular time-dependent uniformly rotating potential in 2 and 3 dimensions: in particular we consider an interaction with support on a point (rotating point interaction) and on a set of codimension 1 (rotating blade). We prove the existence of the Hamiltonians of such systems as suitable self-adjoint operators and we give an explicit expression for their unitary semigroups. Moreover we analyze the asymptotic limit of large angular velocity and we prove strong convergence of the time-dependent propagator to some one-parameter unitary group as (\\\\omega \\\\to \\\\infty).}, doi = {10.1007/s00023-004-0182-8}, url = {http://hdl.handle.net/1963/2945}, author = {Michele Correggi and Gianfausto Dell{\textquoteright}Antonio} } @article {2004, title = {Semiclassical analysis of constrained quantum systems}, journal = {J. Phys. A 37 (2004) 5605-5624}, number = {arXiv.org;math-ph/0312034v2}, year = {2004}, publisher = {IOP Publishing}, abstract = {We study the dynamics of a quantum particle in R^(n+m) constrained by a strong potential force to stay within a distance of order hbar (in suitable units) from a smooth n-dimensional submanifold M. We prove that in the semiclassical limit the evolution of the wave function is approximated in norm, up to terms of order hbar^(1/2), by the evolution of a semiclassical wave packet centred on the trajectory of the corresponding classical constrained system.}, doi = {10.1088/0305-4470/37/21/007}, url = {http://hdl.handle.net/1963/2997}, author = {Gianfausto Dell{\textquoteright}Antonio and Lucattilio Tenuta} } @article {2004, title = {Virasoro Symmetries of the Extended Toda Hierarchy}, journal = {Comm. Math.\\nPhys. 250 (2004) 161-193.}, number = {arXiv.org;math/0308152}, year = {2004}, abstract = {We prove that the extended Toda hierarchy of \\\\cite{CDZ} admits nonabelian Lie algebra of infinitesimal symmetries isomorphic to the half of the Virasoro algebra. The generators $L_m$, $m\\\\geq -1$ of the Lie algebra act by linear differential operators onto the tau function of the hierarchy. We also prove that the tau function of a generic solution to the extended Toda hierarchy is annihilated by a combination of the Virasoro operators and the flows of the hierarchy. As an application we show that the validity of the Virasoro constraints for the $CP^1$ Gromov-Witten invariants and their descendents implies that their generating function is the logarithm of a particular tau function of the extended Toda hierarchy.}, doi = {10.1007/s00220-004-1084-9}, url = {http://hdl.handle.net/1963/2544}, author = {Boris Dubrovin and Zhang Youjin} } @article {2003, title = {Autonomous integral functionals with discontinous nonconvex integrands: Lipschitz regularity of mimimizers, DuBois-Reymond necessary conditions and Hamilton-Jacobi equations}, journal = {Applied Math.Optim. 48 (2003), no.1, p.39-66}, number = {SISSA;55/2002/M}, year = {2003}, publisher = {SISSA Library}, doi = {10.1007/s00245-003-0768-4}, url = {http://hdl.handle.net/1963/1625}, author = {Gianni Dal Maso and Helene Frankowska} } @article {2003, title = {The calibration method for the Mumford-Shah functional and free-discontinuity problems}, journal = {Calc. Var. Partial Differential Equations 16 (2003) 299-333}, number = {SISSA;35/2001/M}, year = {2003}, publisher = {Springer}, abstract = {We present a minimality criterion for the Mumford-Shah functional, and more generally for non convex variational integrals on SBV which couple a surface and a bulk term. This method provides short and easy proofs for several minimality results.}, doi = {10.1007/s005260100152}, url = {http://hdl.handle.net/1963/3051}, author = {Giovanni Alberti and Guy Bouchitte and Gianni Dal Maso} } @article {2003, title = {Hybrid optimal control: case study of a car with gears}, journal = {Int. J. Control 76 (2003) 1272-1284}, year = {2003}, publisher = {Taylor and Francis}, abstract = {The purpose of this paper is to show the use of some analytical tools for hybrid optimal control. We illustrate both the hybrid maximum principle and the hybrid necessary principle at work on a simple example of a car with gears. The model is sufficiently rich to generate non-trivial optimization problems and the obtained results match with intuition. Finally, computer simulations confirm the theoretical analysis.}, doi = {10.1080/0020717031000147520}, url = {http://hdl.handle.net/1963/3022}, author = {Ciro D{\textquoteright}Apice and Mauro Garavello and Rosanna Manzo and Benedetto Piccoli} } @article {2003, title = {Non-linear sigma-models in noncommutative geometry: fields with values in finite spaces}, journal = {Mod. Phys. Lett. A 18 (2003) 2371-2379}, number = {arXiv.org;math/0309143v1}, year = {2003}, publisher = {World Scientific}, abstract = {We study sigma-models on noncommutative spaces, notably on noncommutative tori. We construct instanton solutions carrying a nontrivial topological charge q and satisfying a Belavin-Polyakov bound. The moduli space of these instantons is conjectured to consists of an ordinary torus endowed with a complex structure times a projective space $CP^{q-1}$.}, doi = {10.1142/S0217732303012593}, url = {http://hdl.handle.net/1963/3215}, author = {Ludwik Dabrowski and Thomas Krajewski and Giovanni Landi} } @article {2003, title = {Prescribing scalar and boundary mean curvature on the three dimensional half sphere}, journal = {J. Geom. Anal. 13 (2003) 255-289}, number = {SISSA;36/2001/M}, year = {2003}, publisher = {Springer}, abstract = {We consider the problem of prescribing the scalar curvature and the boundary mean curvature of the standard half three sphere, by deforming conformally its standard metric. Using blow up analysis techniques and minimax arguments, we prove some existence and compactness results.}, doi = {10.1007/BF02930697}, url = {http://hdl.handle.net/1963/3086}, author = {Zindine Djadli and Andrea Malchiodi and Mohameden Ould Ahmedou} } @article {2003, title = {Quantum spin coverings and statistics}, journal = {J. Phys. A 36 (2003), no. 13, 3829-3840}, number = {SISSA;97/2002/FM}, year = {2003}, publisher = {IOP Publishing}, abstract = {SL_q(2) at odd roots of unity q^l =1 is studied as a quantum cover of the complex rotation group SO(3,C), in terms of the associated Hopf algebras of (quantum) polynomial functions. We work out the irreducible corepresentations, the decomposition of their tensor products and a coquasitriangular structure, with the associated braiding (or statistics). As an example, the case l=3 is discussed in detail.}, doi = {10.1088/0305-4470/36/13/314}, url = {http://hdl.handle.net/1963/1667}, author = {Ludwik Dabrowski and Cesare Reina} } @article {2003, title = {A stability result for nonlinear Neumann problems under boundary variations}, journal = {J.Math. Pures Appl. (9) 82 (2003) no.5 , 503}, number = {SISSA;48/2002/M}, year = {2003}, publisher = {SISSA Library}, abstract = {In this paper we study, in dimension two, the stability of the solutions of some nonlinear elliptic equations with Neumann boundary conditions, under perturbations of the domains in the Hausdorff complementary topology.}, doi = {10.1016/S0021-7824(03)00014-X}, url = {http://hdl.handle.net/1963/1618}, author = {Gianni Dal Maso and Francois Ebobisse and Marcello Ponsiglione} } @article {Bertola:CoherentJMP, title = {Coherent state realizations of $\rm su(n+1)$ on the $n$-torus}, journal = {J. Math. Phys.}, volume = {43}, number = {7}, year = {2002}, pages = {3425{\textendash}3444}, issn = {0022-2488}, author = {de Guise, Hubert and Marco Bertola} } @article {2002, title = {Instanton algebras and quantum 4-spheres}, journal = {Differential Geom. Appl. 16 (2002) 277-284}, number = {arXiv.org;math/0101177v2}, year = {2002}, publisher = {Elsevier}, abstract = {We study some generalized instanton algebras which are required to describe {\textquoteleft}instantonic complex rank 2 bundles\\\'. The spaces on which the bundles are defined are not prescribed from the beginning but rather are obtained from some natural requirements on the instantons. They turn out to be quantum 4-spheres $S^4_q$, with $q\\\\in\\\\IC$, and the instantons are described by self-adjoint idempotents e. We shall also clarify some issues related to the vanishing of the first Chern-Connes class $ch_1(e)$ and on the use of the second Chern-Connes class $ch_2(e)$ as a volume form.}, doi = {10.1016/S0926-2245(02)00066-9}, url = {http://hdl.handle.net/1963/3134}, author = {Ludwik Dabrowski and Giovanni Landi} } @article {2002, title = {Linearized elasticity as gamma-limit of finite elasticity}, journal = {Set-Valued Anal. 10 (2002), p.165-183}, number = {SISSA;69/2001/M}, year = {2002}, publisher = {Springer}, doi = {10.1023/A:1016577431636}, url = {http://hdl.handle.net/1963/3052}, author = {Gianni Dal Maso and Matteo Negri and Danilo Percivale} } @article {2002, title = {A model for the quasi-static growth of a brittle fracture: existence and approximation results}, journal = {Math. Models Methods Appl. Sci., 12 (2002), no. 12, 1773}, number = {SISSA;115/00/M}, year = {2002}, publisher = {SISSA Library}, abstract = {We study a variant of the variational model for the quasi-static growth of brittle fractures proposed by Francfort and Marigo.9 The main feature of our model is that, in the discrete-time formulation, in each step we do not consider absolute minimizers of the energy, but, in a sense, we look for local minimizers which are sufficiently close to the approximate solution obtained in the previous step. This is done by introducing in the variational problem an additional term which penalizes the L2-distance between the approximate solutions at two consecutive times. We study the continuous-time version of this model, obtained by passing to the limit as the time step tends to zero, and show that it satisfies (for almost every time) some minimality conditions which are slightly different from those considered in Refs. 9 and 8, but are still enough to prove (under suitable regularity assumptions on the crack path) that the classical Griffith\\\'s criterion holds at the crack tips. We also prove that, if no initial crack is present and if the data of the problem are sufficiently smooth, no crack will develop in this model, provided the penalization term is large enough.}, doi = {10.1142/S0218202502002331}, url = {http://hdl.handle.net/1963/1571}, author = {Gianni Dal Maso and Rodica Toader} } @article {2002, title = {A model for the quasi-static growth of brittle fractures based on local minimization}, journal = {Math.Models Methods Appl. Sci., 12 (2002) , p.1773-1800.}, number = {SISSA;51/2002/M}, year = {2002}, publisher = {SISSA Library}, abstract = {We study a variant of the variational model for the quasi-static growth of brittle fractures proposed by Francfort and Marigo.9 The main feature of our model is that, in the discrete-time formulation, in each step we do not consider absolute minimizers of the energy, but, in a sense, we look for local minimizers which are sufficiently close to the approximate solution obtained in the previous step. This is done by introducing in the variational problem an additional term which penalizes the L2-distance between the approximate solutions at two consecutive times. We study the continuous-time version of this model, obtained by passing to the limit as the time step tends to zero, and show that it satisfies (for almost every time) some minimality conditions which are slightly different from those considered in Refs. 9 and 8, but are still enough to prove (under suitable regularity assumptions on the crack path) that the classical Griffith\\\'s criterion holds at the crack tips. We also prove that, if no initial crack is present and if the data of the problem are sufficiently smooth, no crack will develop in this model, provided the penalization term is large enough.}, doi = {10.1142/S0218202502002331}, url = {http://hdl.handle.net/1963/1621}, author = {Gianni Dal Maso and Rodica Toader} } @article {2002, title = {A Model for the Quasi-Static Growth of Brittle Fractures: Existence and Approximation Results}, journal = {Arch. Ration. Mech. Anal. 162 (2002) 101-135}, number = {SISSA;30/2001/M}, year = {2002}, publisher = {Springer}, abstract = {We give a precise mathematical formulation of a variational model for the irreversible quasi-static evolution of brittle fractures proposed by G.A. Francfort and J.-J. Marigo, and based on Griffith\\\'s theory of crack growth. In the two-dimensional case we prove an existence result for the quasi-static evolution and show that the total energy is an absolutely continuous function of time, although we can not exclude that the bulk energy and the surface energy may present some jump discontinuities. This existence result is proved by a time discretization process, where at each step a global energy minimization is performed, with the constraint that the new crack contains all cracks formed at the previous time steps. This procedure provides an effective way to approximate the continuous time evolution.}, doi = {10.1007/s002050100187}, url = {http://hdl.handle.net/1963/3056}, author = {Gianni Dal Maso and Rodica Toader} } @article {2002, title = {Prescribing a fourth oder conformal invariant on the standard sphere - Part I: a perturbation result}, journal = {Commun. Contemp. Math., 2002, 4, 375}, number = {SISSA;82/00/M}, year = {2002}, publisher = {SISSA Library}, doi = {10.1142/S0219199702000695}, url = {http://hdl.handle.net/1963/1539}, author = {Zindine Djadli and Mohameden Ould Ahmedou and Andrea Malchiodi} } @article {2002, title = {Prescribing a fourth oder conformal invariant on the standard sphere - Part II: blow up analysis and applications}, journal = {Ann. Sc. Norm. Super. Pisa Cl. Sci., 2002, 1, 387}, number = {SISSA;83/00/M}, year = {2002}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/1540}, author = {Zindine Djadli and Andrea Malchiodi and Mohameden Ould Ahmedou} } @article {2001, title = {Dirac operator on the standard Podles quantum sphere}, journal = {Noncommutative geometry and quantum groups (Warsaw 2001),49,Banach Center Publ., 61, Polish Acad.Sci., Warsaw,2003}, number = {SISSA;98/2002/FM}, year = {2001}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/1668}, author = {Ludwik Dabrowski and Andrzej Sitarz} } @article {2001, title = {Gamma-limit of periodic obstacles}, journal = {Acta Appl. Math., 2001, 65, 207-215}, number = {SISSA;37/00/M}, year = {2001}, publisher = {SISSA Library}, abstract = {We compute the Gamma-limit of a sequence obstacle functionals in the case of periodic obstacles.}, doi = {10.1023/A:1010668530972}, url = {http://hdl.handle.net/1963/1495}, author = {Gianni Dal Maso and Paola Trebeschi} } @article {2001, title = {Instantons on the Quantum 4-Spheres S^4_q}, journal = {Comm. Math. Phys. 221 (2001) 161-168}, number = {arXiv.org;math/0012103v2}, year = {2001}, publisher = {Springer}, abstract = {We introduce noncommutative algebras $A_q$ of quantum 4-spheres $S^4_q$, with $q\\\\in\\\\IR$, defined via a suspension of the quantum group $SU_q(2)$, and a quantum instanton bundle described by a selfadjoint idempotent $e\\\\in \\\\Mat_4(A_q)$, $e^2=e=e^*$. Contrary to what happens for the classical case or for the noncommutative instanton constructed in Connes-Landi, the first Chern-Connes class $ch_1(e)$ does not vanish thus signaling a dimension drop. The second Chern-Connes class $ch_2(e)$ does not vanish as well and the couple $(ch_1(e), ch_2(e))$ defines a cycle in the $(b,B)$ bicomplex of cyclic homology.}, doi = {10.1007/PL00005572}, url = {http://hdl.handle.net/1963/3135}, author = {Ludwik Dabrowski and Giovanni Landi and Tetsuya Masuda} } @article {2001, title = {A monotonicity approach to nonlinear Dirichlet problems in perforated domains}, journal = {Adv. Math. Sci. Appl. 11 (2001) 721-751}, number = {SISSA;99/00/M}, year = {2001}, publisher = {SISSA Library}, abstract = {We study the asymptotic behaviour of solutions to Dirichlet problems in perforated domains for nonlinear elliptic equations associated with monotone operators. The main difference with respect to the previous papers on this subject is that no uniformity is assumed in the monotonicity condition. Under a very general hypothesis on the holes of the domains, we construct a limit equation, which is satisfied by the weak limits of the solutions. The additional term in the limit problem depends only on the local behaviour of the holes, which can be expressed in terms of suitable nonlinear capacities associated with the monotone operator.}, url = {http://hdl.handle.net/1963/1555}, author = {Gianni Dal Maso and Igor V. Skrypnik} } @article {2001, title = {Uniqueness of solutions to Hamilton-Jacobi equations arising in the Calculus of Variations}, journal = {Optimal control and partial differential equations : in honour of professor Alain Bensoussan\\\'s 60th birthday / edited by José Luis Menaldi, Edmundo Rofman, and Agnès Sulem.,Amsterdam : IOS Press, 2001, p. 335-345}, number = {SISSA;57/00/M}, year = {2001}, publisher = {SISSA Library}, abstract = {We prove the uniqueness of the viscosity solution to the Hamilton-Jacobi equation associated with a Bolza problem of the Calculus of Variations, assuming that the Lagrangian is autonomous, continuous, superlinear, and satisfies the usual convexity hypothesis. Under the same assumptions we prove also the uniqueness, in a class of lower semicontinuous functions, of a slightly different notion of solution, where classical derivatives are replaced only by subdifferentials. These results follow from a new comparison theorem for lower semicontinuous viscosity supersolutions of the Hamilton-Jacobi equation, that is proved in the general case of lower semicontinuous Lagrangians.}, url = {http://hdl.handle.net/1963/1515}, author = {Gianni Dal Maso and Helene Frankowska} } @article {2000, title = {A(SLq(2)) at roots of unity is a free module over A(SL(2))}, journal = {Lett. Math. Phys., 2000, 52, 339}, number = {SISSA;42/00/FM}, year = {2000}, publisher = {SISSA Library}, doi = {10.1023/A:1007601131002}, url = {http://hdl.handle.net/1963/1500}, author = {Ludwik Dabrowski and Cesare Reina and Alessandro Zampa} } @article {2000, title = {The Calibration Method for Free Discontinuity Problems}, journal = {European Congress of Mathematics. Volume I : Barcelona, July 10-14, 2000 / Carles Casacuberta ... [et al.], editors. , Boston : Birkhauser, 2001, p. 317-326.}, number = {SISSA;38/00/M}, year = {2000}, publisher = {SISSA Library}, abstract = {The calibration method is used to identify some minimizers of the Mumford-Shah functional. The method is then extended to more general free discontinuity problems.}, url = {http://hdl.handle.net/1963/1496}, author = {Gianni Dal Maso} } @article {2000, title = {Local calibrations for minimizers of the Mumford-Shah functional with rectilinear discontinuity sets}, journal = {J. Math. Pures Appl. 79, 2 (2000) 141-162}, number = {SISSA;47/99/M}, year = {2000}, publisher = {SISSA Library}, doi = {10.1016/S0021-7824(99)00140-3}, url = {http://hdl.handle.net/1963/1261}, author = {Gianni Dal Maso and Maria Giovanna Mora and Massimiliano Morini} } @article {2000, title = {Monodromy of certain Painlev{\'e}-VI transcendents and reflection groups}, journal = {Invent. Math. 141 (2000) 55-147}, number = {arXiv.org;math/9806056v1}, year = {2000}, publisher = {Springer}, abstract = {We study the global analytic properties of the solutions of a particular family of Painleve\\\' VI equations with the parameters $\\\\beta=\\\\gamma=0$, $\\\\delta={1\\\\over2}$ and $\\\\alpha$ arbitrary. We introduce a class of solutions having critical behaviour of algebraic type, and completely compute the structure of the analytic continuation of these solutions in terms of an auxiliary reflection group in the three dimensional space. The analytic continuation is given in terms of an action of the braid group on the triples of generators of the reflection group. This result is used to classify all the algebraic solutions of our Painleve\\\' VI equation.}, doi = {10.1007/PL00005790}, url = {http://hdl.handle.net/1963/2882}, author = {Boris Dubrovin and Marta Mazzocco} } @article {2000, title = {A Remark on One-Dimensional Many-Body Problems with Point Interactions}, journal = {Int. J. Mod. Phys. B 14 (2000) 721-727}, number = {arXiv.org;quant-ph/0001089v1}, year = {2000}, publisher = {World Scientific}, abstract = {The integrability of one dimensional quantum mechanical many-body problems with general contact interactions is extensively studied. It is shown that besides the pure (repulsive or attractive) $\\\\delta$-function interaction there is another singular point interactions which gives rise to a new one-parameter family of integrable quantum mechanical many-body systems. The bound states and scattering matrices are calculated for both bosonic and fermionic statistics.}, doi = {10.1142/S0217979200000601}, url = {http://hdl.handle.net/1963/3214}, author = {Sergio Albeverio and Ludwik Dabrowski and Shao-Ming Fei} } @article {2000, title = {Some Properties of Non-linear sigma-Models in Noncommutative Geometry}, journal = {Int. J. Mod. Phys. B 14 (2000) 2367-2382}, number = {SISSA;158/99/FM}, year = {2000}, publisher = {SISSA Library}, abstract = {We introduce non-linear $\\\\sigma$-models in the framework of noncommutative geometry with special emphasis on models defined on the noncommutative torus. We choose as target spaces the two point space and the circle and illustrate some characteristic features of the corresponding $\\\\sigma$-models. In particular we construct a $\\\\sigma$-model instanton with topological charge equal to 1. We also define and investigate some properties of a noncommutative analogue of the Wess-Zumino-Witten model.}, doi = {10.1142/S0217979200001898}, url = {http://hdl.handle.net/1963/1373}, author = {Ludwik Dabrowski and Thomas Krajewski and Giovanni Landi} } @article {2000, title = {Value Functions for Bolza Problems with Discontinuous Lagrangians and Hamilton-Jacobi inequalities}, journal = {ESAIM Control Optim. Calc. Var., 5 (2000), n. 5, p. 369-393.}, number = {SISSA;56/00/M}, year = {2000}, publisher = {SISSA Library}, doi = {10.1051/cocv:2000114}, url = {http://hdl.handle.net/1963/1514}, author = {Gianni Dal Maso and Helene Frankowska} } @article {1999, title = {Asymptotic behaviour of nonlinear elliptic higher order equations in perforated domains}, journal = {Journal d\\\'Analyse Mathematique, Volume 79, 1999, Pages: 63-112}, year = {1999}, isbn = {1618-1891}, doi = {10.1007/BF01759365}, url = {http://hdl.handle.net/1963/6433}, author = {Gianni Dal Maso and Igor V. Skrypnik} } @article {1999, title = {The calibration method for the Mumford-Shah functional}, journal = {C. R. Acad. Sci. Paris Ser. I Math. 329 (1999), no. 3, 249-254}, number = {SISSA;21/99/M}, year = {1999}, publisher = {Elsevier}, abstract = {In this Note we adapt the calibration method to functionals of Mumford-Shah type, and provide a criterion (Theorem 1) to verify that a given function is energy minimizing. Among other applications, we use this criterion to show that certain triple-junction configurations are minimizing (Example 3).}, doi = {10.1016/S0764-4442(00)88602-4}, url = {http://hdl.handle.net/1963/1235}, author = {Giovanni Alberti and Guy Bouchitte and Gianni Dal Maso} } @article {1999, title = {Discrete approximation of the Mumford-Shah functional in dimension two}, journal = {M2AN 33 (1999) 651-672}, year = {1999}, publisher = {EDP Sciences}, doi = {10.1051/m2an:1999156}, url = {http://hdl.handle.net/1963/3588}, author = {Antonin Chambolle and Gianni Dal Maso} } @article {1999, title = {Evans-Vasilesco theorem in Dirichlet spaces}, journal = {Rendiconti di Matematica e delle sue Applicazioni. vol. 19, Issue 7, (1999), pages : 1-15}, year = {1999}, publisher = {SISSA}, url = {http://hdl.handle.net/1963/6436}, author = {Gianni Dal Maso and Virginia De Cicco} } @article {1999, title = {Frobenius manifolds and Virasoro constraints}, journal = {Selecta Math. (N.S.) 5 (1999) 423-466}, number = {SISSA;84/98/FM}, year = {1999}, publisher = {Springer}, abstract = {For an arbitrary Frobenius manifold a system of Virasoro constraints is constructed. In the semisimple case these constraints are proved to hold true in the genus one approximation. Particularly, the genus $\\\\leq 1$ Virasoro conjecture of T.Eguchi, K.Hori, M.Jinzenji, and C.-S.Xiong and of S.Katz is proved for smooth projective varieties having semisimple quantum cohomology.}, doi = {10.1007/s000290050053}, url = {http://hdl.handle.net/1963/2883}, author = {Boris Dubrovin and Zhang Youjin} } @article {1999, title = {A Lipschitz selection from the set of minimizers of a nonconvex functional of the gradient}, journal = {Nonlinear Analysis, Theory, Methods and Applications. Volume 37, Issue 6, September 1999, Pages 707-717}, year = {1999}, publisher = {SISSA}, abstract = {A constructive and improved version of the proof that there exist a continuous map that solves the convexified problem is presented. A Lipschitz continuous map is analyzed such that a map vector minimizes the functional at each vector satisfying Cellina\\\'s condition of existence of minimum. This map is explicitly given by a direct constructive algorithm.}, doi = {10.1016/S0362-546X(98)00067-4}, url = {http://hdl.handle.net/1963/6439}, author = {Gianni Dal Maso and Vladimir V. Goncharov and Antonio Ornelas} } @inbook {1999, title = {Painlev{\'e} transcendents in two-dimensional topological field theory}, booktitle = {The Painlev{\'e} property : one century later / Robert Conte ed. - New York : Springer-Verlag, 1999. - (CRM series in mathematical physics). - p. 287-412}, number = {SISSA;24/98/FM}, year = {1999}, publisher = {Springer}, organization = {Springer}, isbn = {0-387-98888-2}, url = {http://hdl.handle.net/1963/3238}, author = {Boris Dubrovin} } @article {10445, title = {Recurrent procedure for the determination of the free energy ε^2 expansion in the topological string theory}, number = {arXiv:solv-int/990400;}, year = {1999}, institution = {SISSA}, abstract = {We present here the iteration procedure for the determination of free energy ǫ2-expansion using the theory of KdV - type equations. In our approach we use the conservation laws for KdV - type equations depending explicitly on times t1, t2, . . . to find the ǫ2-expansion of u(x, t1, t2, . . .) after the infinite number of shifts of u(x, 0, 0, . . .) = x along t1, t2, . . . in recurrent form. The formulas for the free energy expansion are just obtained then as a result of quite simple integration procedure applied to un(x).

}, url = {http://hdl.handle.net/1963/6489}, author = {Boris Dubrovin and Andrei Ya A Maltsev} } @article {1999, title = {Renormalized solutions of elliptic equations with general measure data}, journal = {Ann. Scuola Norm. Sup. Pisa Cl. Sci. (4) 28 (1999), no. 4, 741-808}, number = {SISSA;22/99/M}, year = {1999}, publisher = {Scuola Normale Superiore di Pisa}, url = {http://hdl.handle.net/1963/1236}, author = {Gianni Dal Maso and Francois Murat and Luigi Orsina and Alain Prignet} } @article {1999, title = {Some properties of the solutions of obstacle problems with measure data}, journal = {Ricerche Matematiche., Supplemento dedicato a Ennio De Giorgi, vol. 48 (1999), page : 99-116}, year = {1999}, url = {http://hdl.handle.net/1963/6432}, author = {Paolo Dall{\textquoteright}Aglio and Gianni Dal Maso} } @article {1999, title = {Variational formulation of softening phenomena in fracture mechanics. The one-dimensional case}, journal = {Arch. Ration. Mech. Anal. 146 (1999), no. 1, 23--58}, number = {SISSA;160/97/M}, year = {1999}, publisher = {Springer}, abstract = {Starting from experimental evidence, the authors justify a variational model for softening phenomena in fracture of one-dimensional bars where the energy is given by the contribution and interaction of two terms: a typical bulk energy term depending on elastic strain and a discrete part that depends upon the jump discontinuities that occur in fracture. A more formal, rigorous derivation of the model is presented by examining the $\\\\Gamma$-convergence of discrete energy functionals associated to an array of masses and springs. Close attention is paid to the softening and fracture regimes. \\nOnce the continuous model is derived, it is fully analyzed without losing sight of its discrete counterpart. In particular, the associated boundary value problem is studied and a detailed analysis of the stationary points under the presence of a dead load is performed. A final, interesting section on the scale effect on the model is included.}, doi = {10.1007/s002050050135}, url = {http://hdl.handle.net/1963/3371}, author = {Andrea Braides and Gianni Dal Maso and Adriana Garroni} } @article {1998, title = {Asymptotic behavior of nonlinear Dirichlet problems in perforated domains}, journal = {Ann. Mat. Pura Appl. (4) 174 (1998), 13--72}, number = {SISSA;162/95/M}, year = {1998}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/1064}, author = {Gianni Dal Maso and Igor V. Skrypnik} } @article {1998, title = {Bihamiltonian Hierarchies in 2D Topological Field Theory At One-Loop Approximation}, journal = {Comm. Math. Phys. 198 (1998) 311-361}, number = {SISSA;152/97/FM}, year = {1998}, publisher = {Springer}, abstract = {We compute the genus one correction to the integrable hierarchy describing coupling to gravity of a 2D topological field theory. The bihamiltonian structure of the hierarchy is given by a classical W-algebra; we compute the central charge of this algebra. We also express the generating function of elliptic Gromov - Witten invariants via tau-function of the isomonodromy deformation problem arising in the theory of WDVV equations of associativity.}, doi = {10.1007/s002200050480}, url = {http://hdl.handle.net/1963/3696}, author = {Boris Dubrovin and Zhang Youjin} } @article {1998, title = {Differential geometry of the space of orbits of a Coxeter group}, journal = {J. Differential Geometry Suppl.4 (1998) 181-211}, number = {SISSA;29/93/FM}, year = {1998}, publisher = {International Press}, abstract = {Differential-geometric structures on the space of orbits of a finite Coxeter group, determined by Groth\\\\\\\'endieck residues, are calculated. This gives a construction of a 2D topological field theory for an arbitrary Coxeter group.}, url = {http://hdl.handle.net/1963/3562}, author = {Boris Dubrovin} } @article {1998, title = {Diffusion of a particle in presence of N moving point sources}, journal = {Annales Poincare Phys.Theor.69:413-424,1998}, number = {SISSA;9/96/ILAS/FM}, year = {1998}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/134}, author = {Gianfausto Dell{\textquoteright}Antonio and Rodolfo Figari and Alessandro Teta} } @article {1998, title = {Extended affine Weyl groups and Frobenius manifolds}, journal = {Compositio Mathematica. Volume 111, Issue 2, 1998, Pages 167-219}, year = {1998}, publisher = {Kluwer}, doi = {10.1023/A:1000258122329}, url = {http://hdl.handle.net/1963/6486}, author = {Boris Dubrovin and Youjin Zhang} } @inbook {1998, title = {Geometry and analytic theory of Frobenius manifolds}, booktitle = {Proceedings of the International Congress of Mathematicians : Berlin 1998, August 18 - 27. II, Invited lectures. - Bielefeld : Universität Bielefeld, Fakultät für Mathematik cop. 1998. - pages : 315-326}, number = {Documenta mathematica;Extra vol.}, year = {1998}, abstract = {Main mathematical applications of Frobenius manifolds are\\r\\nin the theory of Gromov - Witten invariants, in singularity theory, in\\r\\ndifferential geometry of the orbit spaces of reflection groups and of their\\r\\nextensions, in the hamiltonian theory of integrable hierarchies. The theory\\r\\nof Frobenius manifolds establishes remarkable relationships between\\r\\nthese, sometimes rather distant, mathematical theories.}, url = {http://hdl.handle.net/1963/6488}, author = {Boris Dubrovin} } @article {1998, title = {Limits of variational problems for Dirichlet forms in varying domains}, journal = {Journal des Mathematiques Pures et Appliquees. Volume 77, Issue 1, January 1998, Pages 89-116}, year = {1998}, publisher = {SISSA}, doi = {10.1016/S0362-546X(98)00067-4}, url = {http://hdl.handle.net/1963/6440}, author = {Gianni Dal Maso and Virginia De Cicco and Lino Notarantonio and Nicoletta A. Tchou} } @article {1997, title = {Capacity theory for monotone operators}, journal = {Potential Anal. 7 (1997), no. 4, 765-803}, number = {SISSA;6/95/M}, year = {1997}, publisher = {Springer}, abstract = {If $Au=-div(a(x,Du))$ is a monotone operator defined on the Sobolev space $W^{1,p}(R^n)$, $1< p <+\\\\infty$, with $a(x,0)=0$ for a.e. $x\\\\in R^n$, the capacity $C_A(E,F)$ relative to $A$ can be defined for every pair $(E,F)$ of bounded sets in $R^n$ with $E\\\\subset F$. We prove that $C_A(E,F)$ is increasing and countably subadditive with respect to $E$ and decreasing with respect to $F$. Moreover we investigate the continuity properties of $C_A(E,F)$ with respect to $E$ and $F$.}, doi = {10.1023/A:1017987405983}, url = {http://hdl.handle.net/1963/911}, author = {Gianni Dal Maso and Igor V. Skrypnik} } @article {1997, title = {Comportamento asintotico delle soluzioni di problemi di Dirichlet}, journal = {Bollettino della Unione Matematica Italiana A. Volume 7, Issue SUPPL. 11 part 2, June 1997, Pages 253-277}, year = {1997}, note = {This is the title of the conference which was delivered by prof. Dal Maso in Padova during the XV Congress of the \\\"Unione Mathematica Italiana\\\" (Padova, 11-16 settembre 1995)}, url = {http://hdl.handle.net/1963/6438}, author = {Gianni Dal Maso} } @inbook {1997, title = {Flat pencils of metrics and Frobenius manifolds}, booktitle = {Integrable systems and algebraic geometry : proceedings of the Taniguchi symposium 1997, Kobe, June 30 - July 4, 1997 and Research Institute for Mathematical Sciences, Kyoto University, July 7 - 11, 1997 / eds. M.-H. Saito, Y. Shimizu and K. Ueno. - Sing}, number = {arXiv.org;math/9803106v1}, year = {1997}, publisher = {World Scientific}, organization = {World Scientific}, abstract = {This paper is based on the author\\\'s talk at 1997 Taniguchi Symposium \\\"Integrable Systems and Algebraic Geometry\\\". We consider an approach to the theory of Frobenius manifolds based on the geometry of flat pencils of contravariant metrics. It is shown that, under certain homogeneity assumptions, these two objects are identical. The flat pencils of contravariant metrics on a manifold $M$ appear naturally in the classification of bihamiltonian structures of hydrodynamics type on the loop space $L(M)$. This elucidates the relations between Frobenius manifolds and integrable hierarchies.}, isbn = {981-02-3266-7}, url = {http://hdl.handle.net/1963/3237}, author = {Boris Dubrovin} } @inbook {1997, title = {Functionals of the Peierls - Fr{\"o}hlich Type and the Variational Principle for the Whitham Equations}, booktitle = {Solitons, geometry, and topology : on the crossroad / V. M. Buchstaber, S. P. Novikov editors.- Providence : American Mathematical Society, 1997. - ( American mathematical society translations. Series 2. - vol. 179). - pages : 35-44}, number = {American mathematical society translations. Series 2.;v.179}, year = {1997}, publisher = {American Mathematical Society}, organization = {American Mathematical Society}, isbn = {0821806661}, url = {http://hdl.handle.net/1963/6485}, author = {Boris Dubrovin} } @article {1997, title = {Some properties of reachable solutions of nonlinear elliptic equations with measure data}, journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze. S{\'e}r. 4, 25 no. 1-2 (1997), p. 375-396}, year = {1997}, publisher = {SISSA}, url = {http://hdl.handle.net/1963/6434}, author = {Gianni Dal Maso and Annalisa Malusa} } @article {1997, title = {Statistics in space dimension two}, journal = {Lett. Math. Phys. 40 (1997), no. 3, 235-256}, number = {SISSA;5/96/ILAS/FM}, year = {1997}, publisher = {SISSA Library}, abstract = {We construct as a selfadjoint operator the Schroedinger hamiltonian for a system of $N$ identical particles on a plane, obeying the statistics defined by a representation $\\\\pi_1$ of the braid group. We use quadratic forms and potential theory, and give details only for the free case; standard arguments provide the extension of our approach to the case of potentials which are small in the sense of forms with respect to the laplacian. We also comment on the relation between the analysis given here and other approaches to the problem, and also on the connection with the description of a quantum particle on a plane under the influence of a shielded magnetic field (Aharanov-Bohm effect).}, doi = {10.1023/A:1007361832622}, url = {http://hdl.handle.net/1963/130}, author = {Gianfausto Dell{\textquoteright}Antonio and Rodolfo Figari and Alessandro Teta} } @article {1997, title = {Three-Phase Solutions of the Kadomtsev - Petviashvili Equation}, journal = {Studies in Applied Mathematics. Year : 1997 ; Volume: 99 ; Issue: 2 ; Pages: 137-203}, year = {1997}, publisher = {SISSA}, abstract = {The Kadomtsev]Petviashvili KP. equation is known to admit explicit periodic\\r\\nand quasiperiodic solutions with N independent phases, for any integer\\r\\nN, based on a Riemann theta-function of N variables. For Ns1 and 2,\\r\\nthese solutions have been used successfully in physical applications. This\\r\\narticle addresses mathematical problems that arise in the computation of\\r\\ntheta-functions of three variables and with the corresponding solutions of\\r\\nthe KP equation. We identify a set of parameters and their corresponding\\r\\nranges, such that e{\textasciidieresis}ery real-valued, smooth KP solution associated with a\\r\\nRiemann theta-function of three variables corresponds to exactly one choice\\r\\nof these parameters in the proper range. Our results are embodied in a\\r\\nprogram that computes these solutions efficiently and that is available to the\\r\\nreader. We also discuss some properties of three-phase solutions.}, doi = {10.1111/1467-9590.00059}, url = {http://hdl.handle.net/1963/6484}, author = {Boris Dubrovin and Ron Flickinger and Harvey Segur} } @article {1996, title = {A capacity method for the study of Dirichlet problems for elliptic systems in varying domains}, journal = {Rend. Sem. Mat. Univ. Padova 96 (1996), 257--277}, number = {SISSA;87/95/M}, year = {1996}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/989}, author = {Gianni Dal Maso and Rodica Toader} } @article {1995, title = {Capacity and Dirichlet problems in varying domains}, number = {SISSA;47/95/M}, year = {1995}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/950}, author = {Gianni Dal Maso} } @article {1995, title = {Classical solutions for a perturbed N-body system}, journal = {Topological nonlinear analysis, II (Frascati, 1995), 1--86, Progr. Nonlinear Differential Equations Appl., 27, Birkhauser Boston, Boston, MA, 1997}, number = {SISSA;1/96/ILAS/FM}, year = {1995}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/126}, author = {Gianfausto Dell{\textquoteright}Antonio} } @inbook {1995, title = {Geometry of 2D topological field theories}, booktitle = {Integrable systems and quantum groups : lectures given at the 1st session of the Centro internazionale matematico estivo (C.I.M.E.) held in Montecatini Terme, Italy, June 14-22, 1995 / R. Donagi, B. Dubrovin, E. Frenkel... [et al.] ; editors, M. Francavig}, year = {1995}, publisher = {SISSA}, organization = {SISSA}, abstract = {These notes are devoted to the theory of {\textquotedblleft}equations of associativity{\textquotedblright}\\r\\ndescribing geometry of moduli spaces of 2D topological field theories.}, isbn = {3-540-60542-8}, url = {http://hdl.handle.net/1963/6483}, author = {Boris Dubrovin} } @article {1995, title = {Special functions of bounded deformation}, number = {SISSA;76/95/M}, year = {1995}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/978}, author = {Giovanni Bellettini and Alessandra Coscia and Gianni Dal Maso} } @article {1994, title = {Algebraic-geometrical Darboux coordinates in R-matrix formalism}, number = {SISSA;88/1994/FM}, year = {1994}, institution = {SISSA}, url = {http://hdl.handle.net/1963/3655}, author = {P. Diener and Boris Dubrovin} } @article {10521, title = {Integrable functional equations and algebraic geometry}, journal = {Duke Mathematical Journal. Volume: 76, Issue: 2, Pages: 645-668}, year = {1994}, publisher = {SISSA}, doi = {10.1215/S0012-7094-94-07623-0}, url = {http://hdl.handle.net/1963/6482}, author = {Boris Dubrovin and A.S. Fokas and P.M. Santini} } @article {1994, title = {Limits of Dirichlet problems in perforated domains: a new formulation}, journal = {Rend. Istit. Mat. Univ. Trieste 26 (1994) 339-360}, number = {SISSA;167/1994/M}, year = {1994}, publisher = {Universit{\`a} degli Studi di Trieste, Dipartimento di Scienze Matematiche}, url = {http://hdl.handle.net/1963/3649}, author = {Gianni Dal Maso and Rodica Toader} } @inbook {1993, title = {Dispersion relations for non-linear waves and the Schottky problem}, booktitle = {Important developments in soliton theory / A. S. Fokas, V. E. Zakharov (eds.) - Berlin : Springer-Verlag, 1993. - pages : 86-98}, year = {1993}, publisher = {SISSA}, organization = {SISSA}, abstract = {An approach to the Schottky problem of specification of periods of holomorphic differentials\\r\\non Riemann surfaces (or, equivalently, specification of Jacobians among all principaly\\r\\npolarized Abelian varieties) based on the theory of Kadomtsev - Petviashvili equation,\\r\\nis discussed.}, isbn = {3540559132}, url = {http://hdl.handle.net/1963/6480}, author = {Boris Dubrovin} } @article {1993, title = {Geometry and integrability of topological-antitopological fusion}, journal = {Communications in Mathematical Physics. Volume 152, Issue 3, March 1993, Pages 539-564}, year = {1993}, publisher = {SISSA}, abstract = {Integrability of equations of topological-antitopological fusion (being proposed\\r\\nby Cecotti and Vafa) describing the ground state metric on a given 2D topological\\r\\nfield theory (TFT) model, is proved. For massive TFT models these equations\\r\\nare reduced to a universal form (being independent on the given TFT model) by\\r\\ngauge transformations. For massive perturbations of topological conformal field theory\\r\\nmodels the separatrix solutions of the equations bounded at infinity are found\\r\\nby the isomonodromy deformations method. Also it is shown that the ground state\\r\\nmetric together with some part of the underlined TFT structure can be parametrized\\r\\nby pluriharmonic maps of the coupling space to the symmetric space of real positive\\r\\ndefinite quadratic forms.}, doi = {10.1007/BF02096618}, url = {http://hdl.handle.net/1963/6481}, author = {Boris Dubrovin} } @inbook {1993, title = {Integrable systems and classification of 2D topological field theories}, booktitle = {Integrable systems : the Verdier memorial conference : actes du colloque international de Luminy / Olivier Babelon, Pierre Cartier, Yvette Kosmann-Schwarzbach editors. - Boston [etc.] : Birkhauser, c1993. - p. 313-359}, year = {1993}, publisher = {SISSA}, organization = {SISSA}, abstract = {In this paper we consider from the point of view of differential geometry and of the\\r\\ntheory of integrable systems the so-called WDVV equations as defining relations of 2-\\r\\ndimensional topological field theory. A complete classification of massive topological conformal\\r\\nfield theories (TCFT) is obtained in terms of monodromy data of an auxillary\\r\\nlinear operator with rational coefficients. Procedure of coupling of a TCFT to topological\\r\\ngravity is described (at tree level) via certain integrable bihamiltonian hierarchies of\\r\\nhydrodynamic type and their τ -functions. A possible role of bihamiltonian formalism in\\r\\ncalculation of high genus corrections is discussed. As a biproduct of this discussion new\\r\\nexamples of infinite dimensional Virasoro-type Lie algebras and their nonlinear analogues\\r\\nare constructed. As an algebro-geometrical applications it is shown that WDVV is just the\\r\\nuniversal system of integrable differential equations (high order analogue of the Painlev{\textasciiacute}e-\\r\\nVI) specifying periods of Abelian differentials on Riemann surfaces as functions on moduli\\r\\nof these surfaces.}, isbn = {0817636536}, url = {http://hdl.handle.net/1963/6478}, author = {Boris Dubrovin} } @inbook {1993, title = {Topological conformal field theory from the point of view of integrable systems}, booktitle = {Integrable quantum field theories / edited by L. Bonora ... \et al.! - New York : Plenum Press, 1993. - page : 283 - 302.}, year = {1993}, note = {NATO ASI series / B ;v. 310}, publisher = {SISSA}, organization = {SISSA}, abstract = {Recent results on classification of massive topological conformal field theories (TCFT) in terms of monodromy data of auxiliary linear operators with rational coefficients are presented. Procedure of coupling of a TCFT to topological gravity is described (at tree-level approximation) via certain integrable hierarchies of hydrodynamic type and their tau-functions. It is explained how the calculation of the ground state metric on TCFT can be interpreted in terms of harmonic maps. Also a construction of some models via Coxeter groups is described.}, isbn = {0306445344}, url = {http://hdl.handle.net/1963/6479}, author = {Boris Dubrovin} } @article {1993, title = {Workshop on point interactions, Trieste, 21-23 December 1992}, number = {SISSA;8/93/ILAS/MS}, year = {1993}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/71}, author = {Gianfausto Dell{\textquoteright}Antonio} } @article {1992, title = {Hamiltonian formalism of Whitham-type hierarchies and topological Landau - Ginsburg models}, journal = {Communications in Mathematical Physics. Volume 145, Issue 1, March 1992, Pages 195-207}, year = {1992}, publisher = {SISSA}, abstract = {We show that the bi-hamiltonian structure of the averaged Gelfand-Dikii\\r\\nhierarchy is involved in the Landau-Ginsburg topological models (for An-Series):\\r\\nthe Casimirs for the first P.B. give the correct coupling parameters for the perturbed\\r\\ntopological minimal model; the correspondence {coupling parameters} ~ {primary\\r\\nfields} is determined by the second P.B. The partition function (at the tree level) and\\r\\nthe chiral algebra for LG models are calculated for any genus g.}, doi = {10.1007/BF02099286}, url = {http://hdl.handle.net/1963/6476}, author = {Boris Dubrovin} } @article {1992, title = {Integrable systems in topological field theory}, journal = {Nuclear Physics B. Volume 379, Issue 3, 1992, pages : 627-689}, year = {1992}, publisher = {SISSA}, abstract = {Integrability of the system of PDE for dependence on coupling parameters of the (tree-level) primary partition function in massive topological field theories, being imposed by the associativity of the perturbed primary chiral algebra, is proved. In the conformal case it is shown that all the topological field theories are classified as solutions of a universal high-order Painlev{\'e}-type equation. Another integrable hierarchy (of systems of hydrodynamic type) is shown to describe coupling to gravity of the matter sector of any topological field theory. Different multicritical models with the given structure of primary correlators are identified with particular self-similar solutions of the hierarchy. The partition function of any of the models is calculated as the corresponding tau-function of the hierarchy.}, url = {http://hdl.handle.net/1963/6477}, author = {Boris Dubrovin} } @article {1992, title = {A variational method in image segmentation: existence and approximation result}, journal = {Acta Math. 168 (1992), no.1-2, p. 89-151}, number = {SISSA;48/89/M}, year = {1992}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/808}, author = {Gianni Dal Maso and Jean-Michel Morel and Sergio Solimini} } @article {1991, title = {Differential geometry of moduli spaces and its applications to soliton equations and to topological conformal field theory}, year = {1991}, institution = {Scuola Normale Superiore di Pisa}, abstract = {We construct flat Riemannian metrics on moduli spaces of algebraic curves with marked meromorphic function. This gives a new class of exact algebraic-geometry solutions to certain non-linear equations in terms of functions on the moduli spaces. We show that the Riemannian metrics on the moduli spaces coincide with two-point correlators in topological conformal field theory and calculate the partition function for A_n model for arbitrary genus. A universal method for constructing complete families of conservation laws for Whitham-type hierarchies of PDEs is also proposed.}, url = {http://hdl.handle.net/1963/6475}, author = {Boris Dubrovin} } @article {1991, title = {Shape optimization for Dirichlet problems: relaxed formulations and optimally conditions}, journal = {Appl.Math.Optim. 23 (1991), no.1, p. 17-49.}, number = {SISSA;124/89/M}, year = {1991}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/880}, author = {Giuseppe Buttazzo and Gianni Dal Maso} } @article {1991, title = {On systems of ordinary differential equations with measures as controls}, journal = {Differential Integral Equations 4 (1991), no.4, p.739-765.}, number = {SISSA;82/89/M}, year = {1991}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/840}, author = {Gianni Dal Maso and Franco Rampazzo} } @article {1990, title = {Correctors for the homogeneization of monotone operators}, journal = {Differential Integral Equations 3 (1990), no.6, p.1151-1166.}, number = {SISSA;52/89/M}, year = {1990}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/812}, author = {Gianni Dal Maso and Anneliese Defranceschi} } @article {1990, title = {G-convergence of monotone operators}, journal = {Ann. Inst. H. Poincare\\\' Anal. Non Lin{\'e}re 7 (1990), no. 3, 123-160}, number = {SISSA;84/88/M}, year = {1990}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/680}, author = {Valeria Chiad{\`o} Piat and Gianni Dal Maso and Anneliese Defranceschi} } @article {1990, title = {A general chain rule for distributional derivatives}, journal = {Proc. Amer. Math. Soc. 108 (1990), no. 3, 691-702}, number = {SISSA;54/88/M}, year = {1990}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/650}, author = {Luigi Ambrosio and Gianni Dal Maso} } @article {1990, title = {Shape optimization for Dirichlet problems: relaxed solutions and optimality conditions}, journal = {Bull. Amer. Math. Soc. (N.S.) , 23 (1990), no.2, 531-535.}, number = {SISSA;49/89/M}, year = {1990}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/809}, author = {Giuseppe Buttazzo and Gianni Dal Maso} } @article {1989, title = {An approach to the thin obstacle problem for variational functionals depending on vector}, journal = {Comm. Partial Differential Equations, 14 (1989), no.12, 1717-1743.}, number = {SISSA;41/89/M}, year = {1989}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/802}, author = {Gianni Dal Maso and Roberta Musina} } @article {1989, title = {Convergence of unilateral problems for monotone operators}, journal = {J. Analyse Math. 53 (1989), 269--289}, number = {SISSA;126/88/M}, year = {1989}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/722}, author = {Gianni Dal Maso and Anneliese Defranceschi} } @article {1989, title = {Limits of obstacle problems for the area functional.}, journal = {Partial differential equations and the calculus of variations : essays in honor of Ennio De Giorgi. - Boston : Birkhauser, 1989. - p. 285-309}, number = {SISSA;96/87/M}, year = {1989}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/577}, author = {Gianni Dal Maso and Michele Carriero and Antonio Leaci and Eduardo Pascali} } @article {1989, title = {On the number of families of periodic solutions of a Hamiltonian system near equilibrium. II. (English. Italian summary)}, journal = {Boll. Un. Mat. Ital. B (7) 3 (1989), no. 3, 579-590}, number = {SISSA;13/88/FM}, year = {1989}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/609}, author = {Gianfausto Dell{\textquoteright}Antonio and Biancamaria D{\textquoteright}Onofrio} } @article {1989, title = {A pointwise regularity theory for the two-obstacle problem}, journal = {Acta Math. 163 (1989), no. 1-2, 57-107}, number = {SISSA;47/88/M}, year = {1989}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/643}, author = {Gianni Dal Maso and Umberto Mosco and Maria Agostina Vivaldi} } @article {1988, title = {A Kellogg property for {\textmu}-capacities}, journal = {Boll. Un. Mat. Ital. A (7) 2, 1988, no. 1, 127-135}, number = {SISSA;10/87/M}, year = {1988}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/492}, author = {Gianni Dal Maso and Anneliese Defranceschi} } @article {1988, title = {Limits of nonlinear Dirichlet problems in varying domains.}, journal = {Manuscripta Math. 61 (1988), no. 3, 251-278.}, number = {SISSA;54/87/A}, year = {1988}, publisher = {SISSA Library}, abstract = {We study the general form of the limit, in the sense of gamma-convergence, of a sequence of nonlinear variational problems in varying domains with Dirichlet boudary conditions. The asymptotic problem is characterized in terms of the limit of suitable nonlinear capacities associated to the domains.}, url = {http://hdl.handle.net/1963/536}, author = {Gianni Dal Maso and Anneliese Defranceschi} } @article {1988, title = {Methods of stochastic stability and properties of the Gribov horizon in the stochastic quantization of gauge theories}, journal = {Stochastic processes, physics and geompetry (Ascona and Locarno, 1988), 302, World Sci.Publishing,NJ(1990)}, number = {SISSA;57/89/FM}, year = {1988}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/817}, author = {Gianfausto Dell{\textquoteright}Antonio} } @article {1988, title = {Some properties of a class of nonlinear variational $m$-capacities}, journal = {J.Funct.Anal. 79, 1988, no. 2, 476-492}, number = {SISSA;3/87/M}, year = {1988}, publisher = {SISSA Library}, doi = {10.1016/0022-1236(88)90022-5}, url = {http://hdl.handle.net/1963/485}, author = {Gianni Dal Maso and Anneliese Defranceschi} } @article {1988, title = {Variational inequalities for the biharmonic operator with variable obstacles.}, journal = {Ann. Mat. Pura Appl. (4) 153 (1988), 203-227 (1989)}, number = {SISSA;50/87/M}, year = {1988}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/531}, author = {Gianni Dal Maso and Gabriella Paderni} } @article {1987, title = {Integral representation of some convex local functionals.}, journal = {Ricerche Mat. 36 (1987), no. 2, 197-214}, number = {SISSA;15/87/M}, year = {1987}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/497}, author = {Gianni Dal Maso and Gabriella Paderni} } @article {1987, title = {Limits of nonlinear Dirichlet problems in varying domains. (Italian)}, journal = {Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 81, 1987, no. 2, 111-118}, number = {SISSA;4/87/M}, year = {1987}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/486}, author = {Gianni Dal Maso and Anneliese Defranceschi} } @article {1986, title = {Convergence of unilateral convex sets. Optimization and related fields (Erice, 1984)}, journal = {Berlin : Springer-Verlag, 1986, Lecture notes in mathematics, v.1190, p. 181-190}, number = {SISSA;50/84/M}, year = {1986}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/353}, author = {Gianni Dal Maso} } @article {1986, title = {Dirichlet problems for demicoercive functionals}, journal = {Nonlinear anal. 10(1986), no.6, 603-613}, number = {SISSA;03/85/M}, year = {1986}, publisher = {SISSA Library}, doi = {10.1016/0362-546X(86)90145-8}, url = {http://hdl.handle.net/1963/390}, author = {Gabriele Anzellotti and Giuseppe Buttazzo and Gianni Dal Maso} } @article {1985, title = {Flat connections for Lax hierarchies on coadjoint orbits}, journal = {Phys. Lett. A 108 (1985), no. 7, 311-314}, number = {SISSA;73/85/MP}, year = {1985}, publisher = {SISSA Library}, doi = {10.1016/0375-9601(85)90102-1}, url = {http://hdl.handle.net/1963/460}, author = {Giovanni Landi and Sergio De Filippo} } @article {1985, title = {Some necessary and sufficient conditions for the convergence of sequences of unilateral convex sets}, journal = {J. Funct. Anal. 62 (1985), no. 2, 119--159}, number = {SISSA;15/84/M}, year = {1985}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/318}, author = {Gianni Dal Maso} } @article {1985, title = {Some singular perturbation problems in the calculus of variations.}, journal = {Ennio De Giorgi Colloquium, p. 41-49, Research Notes in Mathematics, v.125, London : Pitman, 1985}, number = {SISSA;62/83/M}, year = {1985}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/297}, author = {Gianni Dal Maso} } @article {1985, title = {Weak convergence of measures on spaces of semicontinuous functions.}, journal = {Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 79 (1985), no. 5, 98-106}, number = {SISSA;76/85/MP}, year = {1985}, publisher = {SISSA Library}, url = {http://hdl.handle.net/1963/463}, author = {Gianni Dal Maso and Ennio De Giorgi and Luciano Modica} } @mastersthesis {1984, title = {Spin Structures and Global Conformal Transformations}, year = {1984}, school = {SISSA}, keywords = {Spinors}, url = {http://hdl.handle.net/1963/5854}, author = {Ludwik Dabrowski} }