Notiziario Scientifico
Settimana dal 24 al 30 marzo 2014
Lunedì 24 marzo 2014
Lunedì 24 marzo 2014
Lunedì 24 marzo 2014
Martedì 25 marzo 2014
Martedì 25 marzo 2014
Martedì 25 marzo 2014
Martedì 25 marzo 2014
Martedì 25 marzo 2014
Mercoledì 26 marzo 2014
Mercoledì 26 marzo 2014
Mercoledì 26 marzo 2014
Giovedì 27 marzo 2014
Giovedì 27 marzo 2014
Giovedì 27 marzo 2014
Giovedì 27 marzo 2014
Venerdì 28 marzo 2014
Tutte le informazioni relative a questo notiziario devono pervenire
all'indirizzo di posta elettronica
seminari@mat.uniroma1.it
entro le ore 9 del venerdì precedente la settimana di pubblicazione.
Aula INdAM
09.00 Enrico Valdinoci
Nonlocal diffusion and applications I
11.00 Luca Rossi
Population dynamics in the presence of a line with fast diffusion I
14.00 Andrea Malchiodi
Variational aspects of Liouville equations I
Ore 14:00, Aula C
Seminario di Geometria Algebrica
Dimostrerò (seguendo Beauville) che l'anello di Chow di una varietà abeliana si
decompone nella somma diretta diretta degli autospazi (simultanei) per l'azione indotta dalla
moltiplicazione per n, e discuterò la relazione con le congetture di Bloch-Beilinson.
Esporrò le congetture formulate da Beauville e Voisin sull'anelli di Chow delle
varietà hyperkaehler e darò la dimostrazione (seguendo Beauville e Voisin) per le
superfici K3.
Ore 15:00, Aula Grassano, Università di Roma II
Conferenze del Master in Scienza e Tecnologia Spaziale
Control theory is a branch of mathematics focusing on the problem of controlling, guiding systems on
which one may act by means of a control, like a car, a space shuttle, or a chemical reaction or in
more general any process that we aim at steering to a certain final desired target state. I will
overview several potential applications of that theory and in particular I will focus on aerospace
problems like the orbit transfer or interplanetary space mission design
Aula INdAM
09.00 Stefan Le Coz
Multi-solitons in Nonlinear Schrodinger Equations I
11.00 Enrico Valdinoci
Nonlocal diffusion and applications II
14.00 Andrea Malchiodi
Variational aspects of Liouville equations II
Ore 14:30, Aula 311, Università di Roma III
Seminario di Fisica Matematica
In his seminal 1949 paper, L. Onsager laid the groundwork for the investigation of nematic phases in
systems of long rod-like molecules, which served as a stepping stone in the study of liquid
crystals. He considered a simple model of long thin cylinders interacting via a hard core repulsion,
in which by truncating the virial expansion for the free energy at second order, one can compute the
free energy quite explicitly, and find that there is a first order phase transition from an
isotropic phase to an anisotropic one. This result is not rigorous, since a number of approximations
are made, chief among which the truncating of the virial expansion. From a mathematical physics
perspective, a rigorous adaptation of Onsager's work could prove extremely interesting, since it
would provide an example of a spontaneous breaking of a continuous symmetry. This seems, however, to
be a substantial challenge. This informal seminar's aim is a more modest one. I will describe
Onsager's 1949 paper in some detail, and show how he proved the existence of a nematic transition in
the context of Onsager's approximation, i.e. the truncation of the virial expansion.
Ore 15:30, Aula di Consiglio
Seminario di Modellistica differenziale numerica
Maneuvering of low Earth orbiting small spacecraft can be executed without propellant via
atmospheric differential drag. This talk introduces analytical guidance solutions for short distance
spacecraft re-phasing in circular or low eccentricity orbits, based on input shaping, linearized
equations of motion, and use of differential drag. A Lyapunov based on-off controller is proposed to
track the guidance in the case of a real flight. Simulation results show good promise for future
onboard implementation.
Ore 16:00, Aula D'Antoni, Università di Roma II
Seminario di Analisi Complessa
In 1977 P. Yang asked whether there exist complete immersed complex sub-manifolds f: M -- > C with
bounded image. A positive answer is known for holomorphic curves (k = 1) and partial answers are
known for the case when k > 1. In the talk we will describe how to construct a holomorphic function
on the open unit ball B^N of C , N greater or equal to 2, whose real part is unbounded on every path
in B^N of finite length that ends on the boundary of B^N. This implies the existence of a complete,
closed complex hypersurface in B^N, and gives a positive answer to Yang's question in all dimensions
k, N, 1 < k < N, by providing properly embedded complete complex manifolds.
Ore 17:00, Aula 16, Scuola di Lettere, Filosofia e Lingue, via Ostiense 234
Seminario di Logica Matematica
Aula INdAM
09.00 Luca Rossi
Population dynamics in the presence of a line with fast diffusion II
11.00 Stefan Le Coz
Multi-solitons in Nonlinear Schrodinger Equations II
14.00 Enrico Valdinoci
Nonlocal diffusion and applications III
Ore 14:30, Aula di Consiglio
Seminario di Geometria Algebrica
Hyperkaehler varieties are higher-dimensional generalizations of K3 surfaces, consisting of
fundamental building blocks of varieties with trivial canonical bundles. According to the work of
Beauville and Voisin, the intersection theory of projective K3 surfaces has some particular
degeneracy property. Its generalization to hyperkaehler varieties, namely the Beauville-Voisin
conjecture, says that the cycle class map restricted to the sub-algebra in the Chow ring (with
rational coefficients) generated by the Chern classes of line bundles and the tangent bundle is
injective. I will talk about my result verifying this conjecture for the generalized Kummer
varieties.
Ore 16:00, Aula F, Università di Roma III
Colloquium di Matematica
A classical problem in geometry is the so-called "Uniformization Problem": deform the metric on a
given surface in order to obtain a "best possible "metric", i.e. with constant Gaussian
curvature. We will explore other curvature quantities in geometry: their origin, their role, as well
as the problem of "uniformizing them". We will see how nonlinear PDEs (especially of high order)
play a crucial role in this subject.
Aula INdAM
09.00 Andrea Malchiodi
Variational aspects of Liouville equations III
11.00 Luca Rossi
Population dynamics in the presence of a line with fast diffusion III
14.00 Stefan Le Coz
Multi-solitons in Nonlinear Schrodinger Equations III
Ore 10:00, Aula 1B1, Dipartimento SBAI
Seminario di Geometria
When the Brownian motion does not run off from the space in a finite time, we say that conservation
property holds true. For example, every Euclidean space and all compact Riemannian manifolds are
conservative; however, a Riemannian manifold having a rapid volume growth may fail to be
conservative. In this talk, we will consider this problem for a more general Markov process than a
Brownian motion, and discuss about some recent developments in this topic.
Ore 11:15, Aula 1B1, Dipartimento SBAI
Seminario di Geometria
I will first recall a few known results about the spectrum of the Steklov operator on surfaces, and,
in parallel, about the Laplace spectrum. In the second part, I will present a recent result (in
collaboration with A. Girouard) about the construction of large first nonzero eigenvalue for the
Steklov operator. For the proof, we adapt classical methods of discretization coming from the
classical Laplacian that I will explain.
Ore 14:30, Aula 211, Università di Roma III
Seminario di Geometria
In the first part of this talk we will discuss the existence and uniqueness of Riemannian
submersions from 3-manifolds to surfaces, whose fibers are the integral curves of a unit Killing
vector field. This will be accomplished by considering a geometric function called bundle curvature.
The second part of the talk will be devoted to study surfaces in the total space of such a
submersion which are transverse to the Killing vector field. We will focus on a generalization to
this spaces of the classical Calabi correspondence between minimal surfaces in the Euclidean 3-space
and maximal surfaces in the Minkowski 3-space. Indeed we shall see that the correspondence swaps the
mean curvature of the graph and the bundle curvature of the space, and we will give some
applications.
Ore 12:00, Aula Dal Passo, Università di Roma II
We consider a coupled system of Liouville equations motivated by the study of non-abelian
Chern-Simons vortices, which also describe holomorphic curves in projective spaces. We use improved
versions of Moser-Trudinger inequalities combined with topological arguments to derive general
existence results. These are joint works with L.Battaglia, A.Jevnikar, C.Ndiaye and D.Ruiz.
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