martedi' 28-11-2006 (16:30) - Aula Magna
Nils Dencker (Universita' di Lund) :
Colloquium di Dipartimento -Solvability and the Nirenberg-Treves Conjecture
In the 50's, the consensus was that all linear partial differential equations were solvable. Therefore, it came as a surprise 1957 when Hans Lewy found a non-solvable complex vector field. The vector field is a natural one, it is the Cauchy-Riemann operator on the boundary of a strictly pseudo-convex domain. The fact is that almost all linear PDE's are unsolvable, because of the Hörmander bracket condition. A rapid development in the 60's lead to the conjecture by Nirenberg and Treves in 1969: condition ($\Psi$) is necessary and sufficient for the solvability of partial differential equations of principal type. This is a condition which involves only the sign changes of the imaginary part of the highest order term of the operator along the bicharacteristics of the real part. The Nirenberg-Treves conjecture has recently been proved, see Annals of Mathematics, 163:2, 2006. We shall present the background and the ideas of the proof.
*********************************************
Giulia Curciarello
Segreteria Didattica
tel-050-2213219
email: curciare(a)dm.unipi.it
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mercoledi' 29-11-2006 (16:00) - aula P1, I piano Polo Fibonacci
Alberto D'Onofrio (IEO-Milano) :
Immunoterapia dei tumori e competizione tumore-sistema immune: oncologia matematica e applicazioni cliniche
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Mercoledi' 22 novembre 2006, ore 15.00, Sala Seminari
Gianluca Pacienza (IRMA - Strasbourg)
"La congettura di Green per curve eccezionali su superfici K3"
Abstract: In un lavoro in collaborazione con Marian Aprodu dimostriamo lacongettura di Green per curve eccezionali su superfici K3. Tali curve figurano tra i pochi esempi di curve aventi dimensione di Clifford superiore o uguale a 3.
Nel seminario presentero' le idee principali della dimostrazione, che si basa su un approccio infinitesimale introdotto da Pareschi,unito alla versione per curve nodali di un teorema di Hirschowitz-Ramanan-Voisin.
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Giovedi' 30 Novembre
Aula magna del Dipartimento L.Tonelli
GIORNATA IN RICORDO DI ENNIO DE GIORGI
10.00 Interventi di benvenuto
10.45 Giorgio Letta
Introduzione
11.00 Sergio Spagnolo
I classici teoremi di De Giorgi sulle equazioni differenziali
11.45 pausa
12.15 Antonio Marino
"Anche la scienza ha bisogno di sognare"
13.00 intervallo
14.15 Marco Forti
Le teorie fondazionali di Ennio De Giorgi
15.00 Luigi Ambrosio
De Giorgi e la moderna Teoria Geometrica della Misura
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mercoledi' 22-11-2006 (17:00) - Sala delle Riunioni
Vicentiu Radulescu (University of Craiova, Romania) :
Combined effects in the study of the Lane-Emden-Fowler equation
Abstract. We study the Lane-Emden-Fowler equation with singular nonlinearity and convection term. We establish various existence, non-existence and uniqueness results. Our analysis takes into account the "competition" between the singular, smooth and convection terms, as well as the growth of the gradient term. Related bifurcation results and open problems are also given in this talk.
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mercoledi' 29-11-2006 (15:00) - aula P1, I piano Polo Fibonacci
Generoso Bevilacqua (Dip. di Oncologia- Divisione di Anatomia Patologica) :
Ciclo cellulare e cancro
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mercoledi' 29-11-2006 (18:00) - aula P1, I piano Polo Fibonacci
Alberto D'Onofrio (IEO-Milano) :
Immunoterapia dei tumori e competizione tumore-sistema immune: oncologia matematica e applicazioni cliniche
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>
>
> Istituto di Scienza e Tecnologie dell'Informazione "A. Faedo"
> Consiglio Nazionale delle Ricerche
> Area della Ricerca di Pisa
>
>
> AVVISO DI SEMINARIO
>
> Data: Mercoledi' 15 novembre 2006, ore 14.30
> Relatore: Dr. Thomas Schildknecht
> Affiliazione: Astronomical Institute, University of Bern
> Titolo: Optical Observations of Space Debris in High-Altitude
> Orbits
> Luogo: ISTI - Aula C34 (Ingresso 19 dell'Area di Ricerca)
> Riferimento: Alessandro Rossi e-mail: Alessandro.Rossi(a)isti.cnr.it
> ABSTRACT
>
>
> In the framework of its space debris research activities ESA established
> an optical survey program to study the space debris environment at high
> altitudes, in particular in the geostationary ring and in the
> geostationary
> transfer orbit region. The Astronomical Institute of the University of
> Bern
> (AIUB) performs these surveys on behalf of ESA using ESA's 1-meter
> Telescope
> in Tenerife. We will briefly summarize this program and the main results.
> The main part of the presentation will be dedicated to a discussion of the
> observation techniques used, including the survey scenarios, the object
> detection techniques and the correlation procedures.
>
>
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Come da precedente annuncio:
Oggi pomeriggio alle 15 e alle 16.30, in aula seminari, si terrano i
seminari
A. Suciu (Northeastern, Boston) ,
"Some combinatorial constructions in topology and group theory"
e
S. Papadima (Accademy of Science, Bucharest)
"Cohomology jumping loci and fundamental groups of algebraic varieties"
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SEMINARI DI SISTEMI DINAMICI OLOMORFI (e dintorni)
Mercoledi' 15 novembre ore 14.00
Centro di Ricerca Matematica De Giorgi - Sala Conferenze
David Sauzin (IMCCE)
"Ergodicity and convergence to a Brownian motion in
examples of Arnold ì diffusion."
Abstract:
In the same line of research as [Marco-Sauzin, ETDS 2004],
I construct
examples of near-integrable Hamiltonian systems with
$N+1/2$ degrees of freedom ($N\ge2$), which are as smooth as possible and
as
``unstable'' as possible. They are generated by Hamiltonian functions of
the form $\frac{1}{2}(I_12+\cdots+I_N2) + f(\theta,I,t)$ with Gevrey
functions $f$ which are $1$-periodic in time and arbitrarily small.
The Nekhoroshev theorem [Marco-Sauzin, IHES 2002] forces exponential
stability. Still, for these particular $f$, one can find probability
measures in the phase space such that the first $N-1$ action variables
satisfy a
functional central limit theorem: when properly rescaled, they converge in
law to a Brownian motion (with an exponentially small coefficient of
diffusion, as should be). These probability measures are related to the
product
of the $2(N-1)$-fold Lebesgue measure by a measure supported on a
horseshoe on
the last degree of freedom. There is a related invariant measure $m$ for
the time-$1$ map, which is
$\sigma$-finite but not finite. One can show that, when $N=1$ or $N=2$,
the time-$1$ map is $m$-ergodic. For $N\ge3$, $m$-almost orbit is
biasymptotic to infinity and the system is not ergodic (but there still
exist orbits which are dense in the support of $m$, which is the product
of the first $N-1$ degrees of freedom by the horseshoe).
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> The archive of this list may be retrieved from the web:
> https://mail.sns.it/Lists/dynlist/List.html
> Le lezioni del corso del Prof. David Sauzin proseguiranno in Aula Bianchi
> col seguente orario
>
> dalle 10:30 alle 12:30 del VENERDI'
>
> La prossima lezione sara' quindi la settimana *prossima*,
> ----> venerdi' 17 novembre.<--------
>
> PS: sono disponibili sul sito di David delle dispense (ampliate) che
> possono essere utili per il corso: "Resurgent functions and splitting
> problems" primo link sulla pagina
> http://www.imcce.fr/Equipes/ASD/person/Sauzin/sauz_preprint.php
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> The archive of this list may be retrieved from the web:
> https://mail.sns.it/Lists/dynlist/List.html
>
>
> Le lezioni del corso del Prof. David Sauzin proseguiranno in Aula Bianchi
> col seguente orario
>
> dalle 10:30 alle 12:30 del VENERDI'
>
> La prossima lezione sara' quindi la settimana *prossima*,
> ----> venerdi' 17 novembre.<--------
>
> PS: sono disponibili sul sito di David delle dispense (ampliate) che
> possono essere utili per il corso: "Resurgent functions and splitting
> problems" primo link sulla pagina
> http://www.imcce.fr/Equipes/ASD/person/Sauzin/sauz_preprint.php
>
>
>
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