Notiziario Scientifico
Settimana dal 6 al 12 ottobre 2014
Lunedì 6 ottobre 2014
Martedì 7 ottobre 2014
Martedì 7 ottobre 2014
Mercoledì 8 ottobre 2014
Mercoledì 8 ottobre 2014
Mercoledì 8 ottobre 2014
Giovedì 9 ottobre 2014
Giovedì 9 ottobre 2014
Giovedì 9 ottobre 2014
Venerdì 10 ottobre 2014
Venerdì 10 ottobre 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.
Ore 16:30, Aula C
Seminario di Probabilità e Fisica Statistica
The study of non-equilibrium systems has led to several mathematically
rigorous and general results on the statistics of entropy production
in non-equilibrium systems. These results are generally known under
the name of 'fluctuation theorems' and include the Gallavotti-Cohen
theorem or the Jarzynski equality. My research focuses on performing
experiments in which such results can be tested in real physical
systems. I am interested in assessing their range of validity but even
more interested in exploiting them to develop new measurement
techniques. I will present some recent experiments, in which focused
laser beams (optical tweezers) are used to perform thermodynamic
transformations on single DNA molecules. As a first example I will
show how to use fluctuation theorems to measure the free energy change
across the transformation. As a second example I will discuss how, in
specific cases, fluctuation theorems can be used to measure the full
entropy production in a nano-scale system starting from a partial
measurement through what we call an 'inference' procedure. This last
example provides a new and general application of fluctuation theorems
which we are only beginning to explore.
Ore 09:00, Aula Libera, Ex mattatoio, Largo G.B. Marzi
ore 9,00 Saluti
ore 9,15 "Presentazione del workshop" Paola Magrone, ricercatore di
Matematica, responsabile scientifico
ore 9,30 "Punti critici e origami" Paola Magrone
ore 10,15 "Architettura e forma" Luca Montuori, ricercatore di
Composizione architettonica e urbana
ore 11,00 "Forma e resistenza" Stefano Gabriele, ricercatore di
Scienza delle Costruzioni
ore 11,45 "Strutture pieghevoli" Giovanni Formica, ricercatore di
Scienza delle Costruzioni
ore 12,30 "Tecnologie di carta" Adolfo F. L. Baratta, ricercatore di
Tecnologia Architettura
Ore 14:30, Aula di Consiglio
Discussione di tesi di dottorato
Ore 10:00, Aula Picone
Mini-Workshop "Stochastic Processes, Orderings and Dependence"
14:30 - 15:10 Franco Pellerey (Politecnico di Torino) Stochastic
orders: a brief introduction and Bruno's contributions
15:15 - 15:45 Time for short contributions
15:45 - 16:15 Break
16:15 - 16:55 Enzo Orsingher (University of Rome La Sapienza)
Random fields and processes at finite velocity
17:00-17:40 Isaac Meilijson (Tel Aviv University) Granule membranes
play dice. The quantal nature of secretion
17:45 - 18:00 Closing remarks
Ore 14:00, Aula di Consiglio
Seminario di Algebra e Geometria
Last summer, Maryam Mirzakhani received the Fields medal for "her
outstanding contributions to the dynamics and geometry of Riemann
surfaces and their moduli spaces." We will describe one of her most
famous results, which illustrates the sentence above. This talk is
intended for non-experts.
Ore 16:00, Aula F, Universita' di Roma III
Seminario di Logica Matematica
Most philosophers won't hesitate to nominate 2+2=4 as the paragon of a
mathematical theorem: a complete misunderstanding. We can either see
2+2=4 as a computation, i.e., an activity not involving any sense, any
reasoning: analytic in the kantian acception. Or we can see 2+2=4 as
the result of a reasoning - hence synthetic - however based on
experience : everything can be checked, there is no room for doubt.
This synthetic a posteriori is not typical of mathematics, which is
naturally synthetic a priori. This means that mathematics cannot be
justified - hence the failure of the foundational programs of a
century ago. If these programs didn't succeed in alleviating our -
however, unreasonable - doubts, they however individuated, inside
mathematics, a synthetic a posteriori layer. This on a large scale,
not limited to finite computations. How is it possible to deal with
infinity and still be based on experience? And what does this mean?
Ore 10:30, Aula Riunioni (secondo piano), IAC-CNR (via dei Taurini 19)
Seminario di Algebra e Geometria
Ore 14:30, Aula D'Antoni, Universita' di Roma II
We will consider a chain composed of three coupled rotors, attached to
thermal baths (with possibly different temperatures) at each
extremity. An important feature of this system is that when the middle
rotors oscillates rapidly, the energy of this rotor decreases very
slowly, due to averaging phenomena. We will construct an effective
dynamics for the middle rotor, using averaging techniques, and deduce
a family of Lyapunov functions which will allow us to prove the
ergodicity of the process with arbitrary polynomial rates. This is a
work in collaboration with N. Cuneo and J.-P. Eckmann.
Ore 16:15, Aula di Consiglio
Seminario di Fisica Matematica
Ore 11:00, Aula Verra, Universita' di Roma III
Seminario di Logica Matematica
En termes kantiens, l'objet nu et son type, c'est
analytique/synthétique. L'analytique est ce qu'il reste quand on a
évacué le sens, ie, l'engagement : tout est sur la table. Il se
décline en constatatif (incrémental) et performatif (destructif). Le
paradigme d'unification permet de représenter le performatif sans
agent extérieur. Le synthétique est ce qui donne le sens à
l'analytique ; engagé, il est soumis au doute. Il se divise en deux
branches. L'a posteriori ou format, qui donne un sens à l'analytique
constatatif, consiste à passer des sortes de tests de sortie d'usine,
comme dans les réseaux de démonstration : c'est le sens comme
question. L'a priori ou socialisation donne un sens à l'analytique
performatif, c'est ici que s'insinue le doute fondationnel: c'est le
sens comme usage. Les deux synthétiques sont les deux façons de dire «
A est A » : axiome (a posteriori) et coupure (a priori), rallonge
entre deux prises opposées vs raccordement de prises. Alors que la
rallonge n'est pas soumise au doute, le branchement est problématique,
dangereux. Y a-t-il équilibre entre les droits (la prise comme sortie)
et les devoirs (sa prise opposée comme entrée) ? Le synthétique a
posteriori est formulable à travers une sorte d'analytique non
déterministe. L'objet mathématique se présente finalement comme une
épure, une combinaison véhicule (analytique) + gabarit (synthétique).
Le synthétique a priori combine les épures selon leurs gabarits, leurs
types ; et il n'y a pas de certitude absolue, légitime, quant à ces
combinaisons. Techniquement parlant, le passage aux épures devrait
répondre à un certain nombre de questions irritantes, comme celle de
trouver des habitants au type vide: ce seraient des entités qui ne
séparent pas nettement l'objet et le sujet.
Ore 12:00, Aula di Consiglio
Seminario MoMa
Liquid Crystals (LC) are anisotropic fluids characterized by long
range orientational order and pair correlations. Mesoscale models,
based on the drastic simplification of representing molecules as
simple rigid objects such as spherocylinders or ellipsoids or even
spins on a lattice have been the cornerstone of the first generation
of liquid crystal (LC) theories and computer simulations. While these
approaches are still very valuable in obtaining the general properties
of complex LC one of the most important current challenges is to
relate a realistic molecular structure to physical observables and
predict properties such as morphologies, order parameters, and
phase-transition temperatures. Atomistic molecular dynamics (MD)
simulations, consisting in the numerical solution of Newton equations
of motion for all the atoms in the system now start to make this
possible, also allowing the test of classical theories for bulk LC
(e.g. Maier-Saupe or Onsager). However, for most practical
applications LC are not used in bulk but in thin films where the LC is
aligned with the help of surface interactions, so it is somewhat
surprising that surface effects are still described only empirically,
while little is known on their molecular origin. In the talk we shall
show that computer simulations start to shed some light on the
interfacial behavior of liquid crystals and show examples for the
prediction of the alignment and anchoring of LC at the interface with
different solid surfaces e.g. silicon or crystalline and glassy silica
with different roughness (see figure). Simulations show in various
cases that molecular organizations at the interface differ radically
from those in the bulk, showing either discontinuities or broad
distributions of orientations rather than the simple Dirichlet type
boundary conditions assumed by many continuum type theories. In the
talk an introduction to these systems and a discussion of some open
problems will be presented.
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