
4pm. Marcel Clerc (DFI, U. de Chile)Title: Liquidsolid and liquidliquid like transition in driven granular media
Abstract : The theory of nonideal gases at thermodynamic equilibrium, for instance the van der Waals gas model, has played a central role in our understanding of coexisting phases, as well as the transitions between them. In contrast, the theory fails with granular matter because collisions between the grains dissipate energy, and their macroscopic size renders thermal fluctuations negligible. When a mass of grains is subjected to mechanical vibration, it can make a transition to a fluid state. In this state, granular matter exhibits patterns and instabilities that resemble those of molecular fluids. Here, we report a granular solid–liquid phase transition in a vibrating granular monolayer. Unexpectedly, the transition is mediated by waves and is triggered by a negative compressibility, as for van der Waals phase coexistence, although the system does not satisfy the hypotheses used to understand atomic systems. The dynamic behaviour that we observe—coalescence, coagulation and wave propagation—is common to a wide class of phase transitions. We have combined experimental, numerical and theoretical studies to build a theoretical framework for this transition.
 5 pm. Norelys Aguila Camacho (Department of Electrical Engineering, University of Chile)
Title: Stability analysis of fractional adaptive systems: Motivation, advances and main challenges.
Monday, May 29, 2017
 4pm.: Felipe Poblete (Universidad Austral de Chile, Valdivia, Chile)
L^pMaximal Regularity of Second Order Evolution Equations on the Line. Abstract (pdf)
 5 pm.: Juan Carlos Pozo (Universidad de La Frontera, Temuco, Chile)
Fundamental Solutions of Fully Nonlocal Diffusion Problems. Abstract (pdf)
Monday, May 8, 2017
Sala 2, Facultad de Matemáticas PUC.
 4.pm: Maria Medina (Pontificia Universidad Católica de Chile)
 5.10 pm: Erwin Topp (USACH)
Title: Parabolic equations with Caputo time derivative. Abstract (Pdf)
 4.pm: Alexander Quaas (Universidad Técnica Federico Santa María)
 5.10 pm: Cristobal Quiñinao (Instituto de Ciencias de la Ingeniera – Universidad de O’Higgins)
Some results on largescale dynamics for FitzHughNagumo neurons: the effects of coupling on the fully excitatory case. Abstract (Pdf)
Monday, April 10, 2017
Auditorio Ninoslav Bralic de la Facultad de Matemáticas de la PUC.
 4 pm. : Roberto Cortez (U. Valparaíso y CMM)
Abstract
 5pm,: Fernando Cortez (Escuela Politécnica de Quito, Ecuador)
We consider the Cauchy problem for a particular equation posed on the circle $S^1$. In the literature, this equation represents the compressible hyperelastic rod equation. We prove that a breakdown will occur as soon as a quantity is strictly negative in at least one point of the circle. Our analysis relies on the application of new localinspace blowup criteria for periodic solutions, which involves the computation of several best constants in convolution estimates and weighted Poincaré inequalities. We will also discuss about the impact of this result in other Cauchy problems.
Monday, March 27, 2017
Sala de seminarios del 5to. piso del DIM, U. de Chile.
 4:00pm.: Tetsu Mizumachi (Hiroshima University, Japan)
In the case where the surface tension is weak or negligible, we find a curve of
resonant continuous eigenvalues near 0. Time evolution of these resonant modes
is described by a 1D damped wave equation in the transverse variable and it gives a
linear approximation of the local phase shifts of modulating line solitary waves.
 4:00pm: Serena Dipierro(University of Melbourne)
Title: Nonlinear free boundary problems
Abstract:
This type of problems presents some severe instability: namely, minimizers may not exist; when they exist,they may show a lack of regularity; and minimizers vary in general from scale to scale. We discuss these instability properties and present some regularity results.
 5:10pm: Enrico Valdinoci (U. Melbourne)
We present some recent results on a nonlocal version of the AllenCahn equation, which is also related, at a large scale, to surfaces which minimize a nonlocal perimeter functional. We discuss some features, such as symmetry property, regularity and rigidity results.
 4pm.: Dominique Spehner, Institut Fourier and LPMMC, Universite Grenoble Alpes, France
We study the ground state of a large bosonic system trapped in a symmetric doublewell potential, letting the distance between the two wells increase to infinity with the number of particles. In this context, one expects an interactiondriven transition between a delocalized state (the particles are independent and live in both wells) and a localized state (half of the particles live in each well). We start from the full manybody Schroedinger Hamiltonian in a largefilling situation where the onsite interactions and kinetic energies are comparable. When tunneling is negligible against the interaction energy, we prove a localization estimate showing that the particle number fluctuations in each well are strongly reduced. The modes in which the particles condense are minimizers of nonlinear Schroedingertype functionals.
 5:10pm: Nicolás Torres (DIM U. Chile)
Chulkwang Kwak
Title: Fifthorder modified KdV equation
4:55
Coffee break
5:10pm
Nikola Kamburov
Title: The space of onephase free boundary solutions in the plane
Abstract: In joint work with David Jerison we study the compactness of the space of solutions to the onephase free boundary problem in the disk, whose positive phase is of a fixed genus. We describe the local structure of the free boundary and obtain rigidity estimates on its shape. Via a correspondence due to Traizet, our results are direct counterparts to theorems by Colding and Minicozzi for minimal surfaces.
Abstract:
Monday October 17, 2016
Sala del 7mo. piso del Centro Modelamiento Matemático, U. de Chile.
3pm
Serena Dipierro (The University of Melbourne)
Title: Chaotic orbits for systems of nonlocal equations
Abstract:
We consider a system of nonlocal equations driven by a perturbed periodic potential. We construct multibump solutions that connect one integer point to another one in a prescribed way. In particular, heteroclinc, homoclinic and chaotic trajectories are constructed. This is a joint work with S. Patrizi and E. Valdinoci.
3:50pm
Pausa Café
4:05pm
Matthew Gursky (University of Notre Dame)
Title: Some geometric variational problems and associated Riemannian structures
Abstract:
In this talk I want to describe two problems from geometric analysis that can be reinterpreted as variational problems in an infinitedimensional Riemannian space. The first problem is the well known uniformization theorem for surfaces, and the associated Riemannian structure turns out to be equivalent to the MabuchiSemmesDonaldson metric on the natural Kahler class. In four dimensions the problem I will describe is a special case of the k–Yamabe
problem, a fully nonlinear version of the Yamabe problem. I will explain how the Riemannian interpretation gives unexpected information about the variational properties of this equation.
5pm
Enrico Valdinoci (The University of Melbourne)
Title: Quantitative regularity results for nonlocal minimal surfaces
Abstract:
We present some quantitative properties of minimizers and stable sets for nonlocal interaction functionals, including the nonlocal perimeter as a particular case. These results include BVestimates in every dimension for stable sets
and flatness estimates for local minimizers in dimension 2 and 3. The detailed results have been given in a recent paper joint with
Eleonora Cinti and Joaquim Serra https://arxiv.org/abs/1602.00540
Thursday October 13, 2016
Sala del 5to. piso del Departamento de Ingeniería Matemática DIM, U. de Chile
5pm
Martín de Borbón (Universidad de San Luis)
Title: Blowup limits of KahlerEinstein mettrics with cone singularities
Abstract:
In Geometric Analysis it is often the case where one is interested in solutions to an elliptic equation which have a notion of scale invariant energy. Under suitable assuptions the only way in which solutions can degenerate is by accumulating energy at a finite number of points. Scaling the solutions at these points gives rise to the socalled blowup limits or `bubbles’. These blowup limits are then useful to model the degenration of solutions and to understand the cooresponding compactification of the moduli space of solutions. This general framework arises in the study of Harmonic maps, Jholomorphic curves, YangMills theory and Einstein metrics on fourmanifolds, among others. I will talk about this blowup analysis in the context of KahlerEinstein metrics on a complex surface with cone singularities along a smooth complex curve.
The study of Kahler metrics with cone singularities has been a very active area of research after a fundamental work of Donaldson in 2011 which laid the foundations for the relevant linear theory. These metrics play a key role in the recent proof of the Calabi conjecture for Fano manifolds by ChenDonaldsonSun and Tian. Besides that, KahlerEinstein metrics with cone singularities have intrinsic interest; as they interact with the study of pairs of complex manifolds together with a divisor in Algebraic Geometry.
Monday September 4, 2016
Sala de seminarios del 5to. piso del Departamento de Ingeniería Matemática DIM, U. de Chile
4:00pm
Karina Vilches (U. Católica del Maule)
Title: Simultaneous Blowup for two species PatlackKellerSegel System in $\mathbb R^2$.
Abstract: See the PDF.
4:55 Pausa Café
5:10pm
Gianmarco Sperone (DIM U. Chile)
Title: Further remarks on the LuoHou’s ansatz for a selfsimilar solution to the 3D Euler equations
Abstract:
It is shown that the selfsimilar ansatz proposed by T. Hou and G. Luo to describe a blowup solution of the 3D axisymmetric Euler equations leads, without assuming any asymptotic condition on the selfsimilar profiles, to an overdetermined system of partial differential equations that produces two families of solutions: a class of trivial solutions in which the vorticity field is identically zero, and a family of solutions that blowup immediately, where the vorticity field is governed by a stationary regime. In any case, the analytical properties of these solutions are not consisent with the numerical observations reported by T. Hou and G. Luo. Therefore, this result is a refinement of the previous work published by D. Chae and T.P. Tsai on this matter, where the authors find the trivial class of solutions under a rather unjustified decay condition of the blowup profiles.
Monday August 22, 2016
Sala de Seminarios del 5to piso DIM U. de Chile
4:00pm.
Boumediene Abdellaoui (Tlemcen University)
Title: Towards a deterministic KPZ equation with fractional diffusion: the stationary case
Abstract: see the PDF.
Monday August 8, 2016
Sala 5, Facultad de Matemáticas PUC
4pm
Mariel Sáez (Pontificia Universidad Católica de Chile)
Title: Fractional Laplacians and extension problems: the higher rank case (joint with M.M. Gonzalez)
Abstract:
In previous work by A.Chang and M.M. Gonzalez the authors studied the connection between the fractional laplacian defined via the extension problem proposed in work of Caffarelli and Silvestre and a class of conformally covariant operators in conformal geometry.
In this talk I will describe a new family of fractional operators that arise from extending the work of A.Chang and M.M. Gonzalez to products of manifolds. These fractional operators can be understood from the view point of L.Caffarelli and L.Silvestre as considering extensions into two different directions and studying a Dirichlet to Neumann map type of problem associated to a degenerate elliptic pde system.
5pm
Duvan Henao (Pontificia Universidad Católica de Chile)
Title: Existence theorems for geometrically nonlinear models of nematic elastomers
Abstract:
We will discuss recent models for nematic elastomers by Barchiesi & DeSimone and by Calderer, Garavito, & Yan, which involve simultaneously an elastic energy defined in the reference configuration and an energy that penalizes spatial variations of the nematic orientation in the deformed configuration. A local invertibility property for orientationpreserving Sobolev maps is used in order to establish the existence of minima. We present a refinement of the theories in which the hypotheses on the coercivity of the energy functions are slightly weakened. This is made possible by the results on the regularity of the inverses of Sobolev maps obtained by Henao & MoraCorral in the analysis of cavitation and fracture in nonlinear elasticity.
Monday June 18, 2016
Sala de Seminarios DIM U. de Chile 5º piso, Beauchef 851, Edificio Norte
5pm
Andrés Zúñiga (Indiana University, http://pages.iu.edu/~ajzuniga/)
Title: On the heteroclinic connection problem for multiwell gradient systems
Abstract:
In this talk we revisit the existence problem of vectorvalued heteroclinic connections associated with Hamiltonian systems involving potentials W having several global minima in R^N. First we will review the standard results on this problem. Secondly, we present a simple variational approach to first find geodesics minimizing length of curves joining any two of the potential wells, where length is computed with respect to a degenerate metric having conformal factor W^(1/2). Then we show that when such a minimizing geodesic avoids passing through other wells of the potential at intermediate times, it gives rise to a heteroclinic connection between the two wells. This work improves upon the approach of P. Sternberg and represents a more geometric alternative to the approaches of e.g. N.D. AlikakosG. Fusco and J. Byeon P. Montecchiari P. Rabinowitz, for finding such connections.
Monday June 6, 2016
Sala 5 Facultad de Matemáticas, Pontificia Universidad Católica de Chile
5:00pm
Gyula Csató (Universidad de Concepción)
Title: About HardySobolev, MoserTrudinger and isoperimetric inequalities with densities
Abstract:
The standard isoperimetric inequality states that among all sets with a given fixed volume (or area in dimension 2) the ball has the smallest perimeter. [See the attached pdf version of the abstract for a more precise statement.] The isoperimetric problem with density is a generalization of this question: given two positive functions f and g from R^2 to R, one studies the existence of minimizers of $\int_{\partial \Omega} g(x)$ among all domains $\Omega$ such that $\int_\Omega f(x)$ equals a fixed given constant. I will talk about some results when f(x)=x^q and g(x)=x^p, where p,q are real numbers. This is a rich problem with strong variations in difficulties depending on the values of p and q. I will first give an overview on Sobolev, HardySobolev and MoserTrudinger inequalities and establish a different kind of connections to isoperimetric inequalities with densities. Finally I will present some of the results appearing in the following references:
 Csató G., An isoperimetric problem with density and the HardySobolev inequality in R^2, Differential Integral Equations, 28, Number 9/10 (2015), 971988.
 Csató G. and Roy P., Extremal functions for the singular MoserTrudinger inequality in 2 dimensions, Calc. Var. Partial Differential Equations, 54, Issue 2 (2015), 23412366.
 Csató G. and Roy P., The singular MoserTrudinger inequality on simply connected domains, Comm. Partial Differential Equations, to appear.
Monday May 2, 2016
Sala 2 Facultad de Matemáticas, P.U.C.
5:00 pm
María Medina (Pontificia Universidad Católica de Chile)
Title: The effect of the Hardy potential in some CalderónZygmund properties for the fractional Laplacian
Abstract:
In this talk we will consider a nonautonomous problem (see attached pdf) involving the fractional Laplacian, a source term f(x), and a homogeneous Dirichlet condition outside a bounded domain. We will study its solvability, and the summability of the corresponding solution, according to the integrability of f(x), in the spirit of the classical results of Stampacchia. In particular, we will try to find the optimal conditions on f(x) and a parameter lambda (of eigenvalue type) in order to obtain a solution, seeing that the techniques applied in BoccardoOrsinaPeral’ 06, where the authors study the problem for the classical Laplacian, do not provide optimality in this setting.
This work can be found in [AbdellaouiMedinaPrimoPeral, JDE 260 (2016) 81608206].
Monday April 25, 2016
Sala de seminarios D.I.M. (5to piso), U. de Chile
5:00 pm
Carlos Román (Université Pierre et Marie Curie – Paris VI,
https://www.ljll.math.upmc.fr/~roman/)
Title: On the first critical magnetic field in the threedimensional GinzburgLandau model of superconductivity
Abstract:
In this talk I will describe the behavior of global minimizers, close to the first critical field, of the GinzburgLandau energy with external magnetic field, for extreme typeII superconductors. I will present results by Sylvia Serfaty and Etienne Sandier in a twodimensional reduced problem and new results concerning the full threedimensional GLfunctional.
Tuesday April 19, 2016
Sala de seminarios del Departamento de Ingeniería Matemática de la Universidad de Chile
5º piso, Beauchef 851, Edificio Norte
3:00 pm
Michel Chipot (Universität Zürich, http://user.math.uzh.ch/chipot/)
Title: Nonhomogeneous boundary value problems for the stationary NavierStokes equations in twodimensional domains with semiinfinite outlets
Abstract:
We would like to present existence results for stationary nonhomogeneous NavierStokes systems (see attached pdf). The boundary value for the fluid velocity is assumed to have compact support and the domain occupied by the fluid is supposed to be unbounded and having outlets to infinity. The core of the technique is the construction of solenoidal extensions of the boundary value satisfying the socalled LerayHopf condition.
Tuesday April 12, 2016
Sala de seminarios del Departamento de Ingeniería Matemática de la Universidad de Chile 5º piso, Beauchef 851, Edificio Norte
3:00 pm
Miguel Ángel Alejo (Universidade Federal de Santa Catarina, https://sites.google.com/site/miguelalejo/)
Title: Stability of mKdV breathers and numerical results
Abstract:
In this talk I will show some recent results about the stability of breather solutions of mKdV. I will also present some numerical results about the study of the spectra of linearized operators around breather solutions of other nonlinear PDEs bearing this kind of solution.
Monday March 14, 2016
Sala de seminarios del Departamento de Ingeniería Matemática de la Universidad de Chile
5º piso, Beauchef 851, Edificio Norte
5:00pm
Marek Fila (Comenius University, http://www.iam.fmph.uniba.sk/institute/fila/)
Title: Extinction of solutions of the fast diffusion equation with critical and subcritical exponents
Abstract:
We discuss the asymptotic behaviour near extinction of positive solutions of the fast diffusion equation with critical and subcritical exponents. By a suitable rescaling, the equation is transformed to a nonlinear FokkerPlanck equation. Among other things, we show that the rate of convergence to regular and singular steady states of the transformed equation can be arbitrarily slow for suitable initial data. Our results reveal the difference in the rates occurring in the critical and the subcritical case. They also yield new classes of extinction rates for the fast diffusion equation.
Wednesday January 13, 2016
Sala de seminarios del Departamento de Ingeniería Matemática de la Universidad de Chile
4:00pm
Sylvain Ervedoza (U. Toulouse)
Title: Local exact controllability for compressible NavierStokes equations
around constant trajectories
Abstract:
In this talk, I will present a recent result obtained on the local
exact controllability of the 3d compressible NavierStokes equation
around a constant trajectory with nonzero velocity, when the control
is exerted on the whole boundary of the domain. The proof of this
result is based on an observability inequality for the adjoint of the
linearized system. The main ingredient to obtain this inequality is
the tricky combination of the equations to reduce the problem to a
closed subsystem easier to deal with, and obtained by the introduction
of a new quantity corresponding to the effective viscous flux for the
adjoint equations. This subsystem will allow to understand
independently the hyperbolic and parabolic effects of the system. We
will then introduce Carleman estimates with weight functions following
the characteristics allowing to handle the nonlinearity of the model
using a fixed point argument. This result has been obtained in
collaboration with Olivier Glass (Univ. Paris Dauphine) and Sergio
Guerrero (Univ. Pierre et Marie Curie).
4:50pm
Pausa Café
5:05pm
André de Laire (U. Lille)
Title: Global wellposedness for a nonlocal GrossPitaevskii equation with
nonzero condition at infinity
Abstract:
In this talk we consider the GrossPitaevskii equation involving a nonlocal
interaction potential. Our aim is to give sufficient conditions that cover
a variety of nonlocal interactions such that the associated Cauchy problem
is globally wellposed with nonzero boundary condition at infinity, in
any dimension. We focus on even potentials that are positive definite or
positive tempered distributions.
We also discuss some nonexistence results for traveling waves solutions
to this equation.