Categoria: seminari

SEMINARIO MATEMATICO E FISICO DI MILANO

AVVISO DI CONFERENZA

Martedi 14 giugno 2011, alle ore 14:30 presso l’aula seminari 3014 del Dipartimento di Matematica e Applicazioni, Università di Milano Bicocca in Via Cozzi 53

Prof. De Witt Sumners Department of Mathematics Florida State University

terra’ la conferenza

“DNA Topology”

Abstract: This lecture will give an introduction to the topology and geometry of DNA. Cellular DNA is a long, thread-like molecule with remarkably complex topology. Enzymes that manipulate and carefully control the geometry and topology of cellular DNA perform many important cellular processes (including segregation of daughter chromosomes, gene regulation, DNA repair, and generation of antibody diversity). Some enzymes pass DNA through itself via enzyme-bridged transient breaks in the DNA; other enzymes break the DNA apart and reconnect it to different ends. In the topological approach to enzymology, circular DNA is incubated with an enzyme, producing an enzyme signature in the form of DNA knots and links. By observing the changes in DNA geometry (supercoiling) and topology (knotting and linking) due to enzyme action, the enzyme binding and mechanism can often be characterized. This talk is intended for a general scientific audience, and will discuss topological models for DNA strand passage and exchange, including the analysis of topoisomerase experiments on circular DNA using knot theory.

Tutti gli interessati sono invitati a partecipare.

Il Direttore del Seminario Franco Tomarelli

Per ulteriori informazioni sulla attivita’ del seminario: http://www.mate.polimi.it/smf

SEMINARIO DI GEOMETRIA ALGEBRICA

Martedì 7 Giugno 2011 alle ore 15

presso l’aula C del Dipartimento di Matematica dell’Università  di Milano

Stefano Urbinati

(University of Utah)

terrà un seminario dal titolo

Divisorial models on non-Q-Gorenstein varieties

Abstract: Based on the construction of de Fernex and Hacon, we study the behavior of the singularities on non-Q-Gorenstein varieties, in particular for which the canonical ring is not a finitely generated O_X-algebra. We give an example of a non Q-Gorenstein variety whose canonical divisor has an irrational valuation and example of a non Q-Gorenstein variety which is canonical but not klt. We also give an example of an irrational jumping number and we prove that there are no accumulation points for the jumping numbers of normal non-Q-Gorenstein varieties with isolated singularities.We also prove that Canonical singularities are equivalent to the finite generation of the canonical ring.Finally, we are trying to introduce a notion of nefness in this new setting, with studying the behavior of the new feature.

Nell’ambito delle attività del Dottorato in Matematica, il Prof EYAL GOREN dell’Università McGill, Montreal – Canada terrà un seminario su “Recent developments in the theory of complex multiplication” presso il Dipartimento di Matematica dell’Università degli Studi di Milano Via C. Saldini n.50 – Milano

Abstract Our story begins more than a century ago with Kronecker’s Jugendtraum and Hilbert’s 12th problem, where complex multiplication appears as a way to understand Galois extensions of number fields – a problem still at the heart of number theory. Our lecture will have a strong historical flavour; we shall attempt to survey the development of the theory of complex multiplication and the philosophy behind it. On this background, we will present some exciting recent results, some of which build in an essential way on Borcherds’ theory. Finally, we shall sketch some of the key challenges of the theory of complex multiplication today and future directions.

Calendario Lunedì 27 giugno 2011, dalle ore 17.00 alle 19.00, presso la Sala di Rappresentanza

Locandina_Goren.pdf

Lezioni LEONARDESCHE

Martedi’ 7 giugno 2011, ore 16.30, in Aula Chisini, via Saldini 50,

il Professore JUAN LUIS VAZQUEZ Universidad Autonoma de Madrid

parlera’ su

NONLINEAR DIFFUSION, FROM POROUS MEDIA TO FRACTIONAL DIFFUSION. EVOLUTIONS, FREE BOUNDARIES AND ASYMPTOTICS

Abstract: In the talk we will make a presentation of the theory of Nonlinear Diffusion centered on one of the popular models, the porous medium equation and its close relative, the fast diffusion equation. The existence of free boundaries is one of the most peculiar properties of the former equation. Related models and literature will be mentioned. In the final section, I will present recent work that combines degenerate nonlinear diffusion with nonlocal operators of fractional Laplacian type. Apart from the unexpected existence of free boundaries, the model admits mass preserving self-similar solutions that are found by solving an elliptic fractional-Laplacian obstacle problem. We use entropy methods to show that the asymptotic behaviour is described after renormalization by these self-similar solutions. This is intended to give an idea of the variety of topics and techniques in the area.

ABOUT THE SPEAKER: Juan Luis Vazquez is a leading expert in the fields of nonlinear partial differential equations and their applications. He is well known for his numerous contributions such as strong maximum principles and blow up analysis for non linear elliptic and parabolic problems and the analysis of diffusion processes such as those and their applications, especially for porous media. Vazquez has recieved the Spanish National Prize for Research in Mathematics in 2003, has delived a plenary address at the 2006 International congress of Mathematicians, and has served as President of the Spanish Society for Applied Mathematics. Vazquez is currently Full Professor of Mathematics at Universidad Autonoma de Madrid in Spain.