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Direttore Vicario: Prof. Gabriele Grillo
Responsabile Gestionale: Dr.ssa Franca Di Censo

 Seminari

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Prossimi Seminari

  • Laser "su misura" per il trattamento di tumori
    Paola Saccomandi, Politecnico di Milano
    mercoledì 27 marzo 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Some remarks on the forces exerted by a viscous fluid on a bluff body
    Gianmarco Sperone, Politecnico di Milano
    giovedì 28 marzo 2019 alle ore 15:15, Aula seminari 3° piano
  • Simplicial splines for representation of density functions
    Karel Hron e Jitka Machalova, Palacky University di Olomouc
    martedì 2 aprile 2019 alle ore 15:00 precise, Aula Seminari 'Saleri' VI Piano MOX-Dipartimento di Matematica, Politecnico di Milano - Edificio 14
  • Stima del valore aggiunto di scuola: stato dell'arte del modello INVALSI e prospettive. Quali implicazioni di policy?
    Tommaso Agasisti, Politecnico di Milano
    mercoledì 3 aprile 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • On the modelling of particle and pedestrian motion with Fokker-Planck equations
    Alfio Borzì, University of Wuerzburg -Germania-
    giovedì 4 aprile 2019 alle ore 14:00, Aula Consiglio VII Piano - Edificio 14, Dipartimento di Matematica POLITECNICO DI MILANO
  • Problemi di frontiera libera nelle scienze applicate
    Sandro Salsa, Politecnico di Milano
    mercoledì 10 aprile 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Errori sistematici e confondimento degli studi osservazionali basati sui dati dal mondo reale
    Giovanni Corrao, Università degli Studi di Milano-Bicocca
    mercoledì 8 maggio 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Inverse Problems in Adaptive Optics
    Ronny Ramlau, RICAM, Austrian Academy of Sciences, Linz, Austria
    mercoledì 8 maggio 2019 alle ore 14:00, Aula Consiglio VII Piano - Edificio 14, Dipartimento di Matematica POLITECNICO DI MILANO
  • Forma e complessità in Natura: perché il mondo è matematico?
    Pasquale Ciarletta, Politecnico di Milano
    mercoledì 15 maggio 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Matematica, società, economia e sviluppo
    Giulia di Nunno, University di Oslo
    mercoledì 22 maggio 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Comunicare il progetto. Storytelling e tecniche di rappresentazione
    Francesca Piredda, Politecnico di Milano
    mercoledì 29 maggio 2019 alle ore 12:15, Politecnico di Milano Campus Bonardi Edificio14 aula B21
  • Semi-implicit finite-volume integrators for all-scale atmospheric dynamics
    Piotr Smolarkiewicz, European Centre for Medium-Range Weather Forecasts, Reading, Berkshire, United Kingdom
    giovedì 30 maggio 2019 alle ore 14:00, Aula Consiglio VII Piano - Edificio 14, Dipartimento di Matematica POLITECNICO DI MILANO

Seminari Passati

  • Waring loci and decompositions of low rank symmetric tensors
    Alessandro Oneto , Barcelona Graduate School of Mathematics
    mercoledì 5 dicembre 2018 alle ore 12:00 precise, Aula seminari III piano
    ABSTRACT
    Given a symmetric tensor, i.e., a homogeneous polynomial, a Waring decomposition is an expression as sum of symmetric decomposable tensors, i.e., powers of linear forms. We call Waring rank of a homogenous polynomial the smallest length of such a Waring decomposition. Apolarity theory provides a very powerful algebraic tool to study Waring decompositions of a homogeneous polynomial by studying sets of points apolar to the polynomial, i.e., sets of points whose defining ideal is contained in the so-called apolar ideal of the polynomial. In this talk, I want to introduce the concept of Waring locus of a homogeneous polynomial, i.e., the locus of linear forms which may appear in a minimal Waring decomposition. Then, after showing some example on how Waring loci can be computed in specific cases via apolarity theory. I explain how they may be used to construct minimal Waring decompositions. These results are from recent joint works with E. Carlini, M.V. Catalisano, and B. Mourrain.
  • Turbulence versus Mathematics and vice versa
    Arkady Tsinober, Tel Aviv University
    martedì 4 dicembre 2018 alle ore 16:00, Aula 3015 del Dipartimento di Matematica e Applicazioni dell'Università di Milano - Bicocca
    ABSTRACT
    It is much easier to present nice rational linear analysis than it is to wade into the morass that is our understanding of turbulence dynamics. With the analysis, professor and students feel more comfortable; even the reputation of turbulence may be improved, since the students will find it not as bad as they had expected. A discussion of turbulence dynamics would create only anxiety and a perception that the field is put together out of folklore and arm waving.” John Lumley, 1987.

    From the outset I have to confess that I find myself 99% in agreement with John Lumley’s concern on “theories of turbulence”. This includes the first premise – i.e. the absence of a theory based on first principles. The second aspect concerns the importance of experiments and observations (both physical and numerical), below referred to as evidence. This lecture is intended to be, first and foremost, a critical presentation and examination of some fundamentally important issues.

    * What do we really mean by ‘conventionally defined inertial range’ (CDIR)? Are its properties really independent of (the nature of) dissipation and/or large-scale forcing? Thus, is the inertial range a well defined concept or is it a mis-conception? Who is the guilty party for dissipation anomaly in turbulent flows? And what about the role of the self-amplification processes of vorticity, strain and super-helicity? Also, how well-defined and meaningful is the so-called ‘decomposition’ of energy in inertial and dissipative ranges?

    * Is the ‘anomalous scaling’ an attribute of the inertial range? And of passive turbulence?

    * Is the ‘4/5 law’ a purely inertial relation?

    * Why should one expect that in the CDIR at very high Reynolds numbers the Navier–Stokes equations (NS) are invariant under infinitely many scaling groups (like the Euler equations), in the statistical sense of K41 labeled by an arbitrary real scaling exponent h? And more generally, should one expect to restore in some sense all the symmetries of Euler equations in the CDIR? And why necessarily Euler?

    * Are weak solutions of Euler equations going to describe adequately a turbulent flow? Is the inviscid limit of NS always independent of the nature of dissipation and viscosity? Is it possible that the Reynolds dependence differs, but the limit (in distributional sense) remains the same? What does it happen to the solenoidal part of the acceleration as viscosity goes to zero? Could the ‘real’ inertial range of turbulence be adequately described by a suitable singular solution of some sort of Euler-like equations?

    * About the concept of ‘non-locality’ of turbulence: is ‘cascade’ a well defined concept and is there a cascade in physical space? Is ‘cascade’ Eulerian, Lagrangian or what? These and other related questions will be briefly touched upon depending on the discussion and interest.


    References
    TSINOBER, A. 2009 An Informal Conceptual Introduction to Turbulence, Springer-Verlag.
    TSINOBER, A. 2018 The Essence of Turbulence as a Physical Phenomenon. II edition (in press), Springer-Verlag.
  • Emodinamica della circolazione epatica: problemi e nuove acquisizioni
    Massimiliano Tuveri, Azienda Ospedaliera Universitaria Integrata, Verona, Italy
    giovedì 29 novembre 2018 alle ore 11:30, aula consiglio VII piano
    ABSTRACT
    : Il fegato ha una vascolarizzazione peculiare comparata con gli altri organi. Ha infatti afferente vascolari di tipo arterioso (arteria epatica) e venoso (vena porta) che confluiscono nel sistema sinusoidale del fegato. Da qui si diparte una efferenza unica venosa rappresentata dalle vene sovraepatiche. La vascolarizzazione intraparenchimale ha una struttura complessa: si divide in due lobi distinti e autonomi ognuno dei quali presenta dei segmenti (8 in tutto) che sono perfusi indipendentemente. Questo riveste una particolare importanza dal punto di vista clinico, specialmente chirurgico, quando si tratta di rimuovere parte del fegato. La quantità di fegato necessaria per la sopravvivenza del paziente, quando per motivi oncologici debba essere asportata ampia parte del fegato, è difficile da predire. Il rischio di insufficienza epatica acuta è infatti molto alto. Il paziente inoltre sviluppa un particolare quadro emodinamico rappresentato da uno stato circolator!
    io ipercinetico con aumento della gittata cardiaca e basse pressioni periferiche, aumento delle resistenze intraparenchimali epatiche e aumento della pressione portale con sviluppo di vie collaterali portosistemiche. I meccanismi alla base della rigenerazione epatica, che permettono al restante parenchima di rimanere vitale e assicurare le funzioni vitali, sono fondamentalmente regolati dallo shear stress arterioso ma sopratutto venoso. Il severo aumento della shear stress è stato posto anche in relazione al danno sinusoidale per l’espressione patologica di sostanze vasoattive.
    Un fattore chiave appare la comprensione dell’entità e del comportamento dello shear stress nel sistema portale. Vi è come detto una correlazione diretta tra la variazione e il gradiente dello shear stress e la modificazione della microcircolazione epatica e la secrezione endoteliale di sostanze vasoattive. La modellazione del fegato e delle sue componenti emodinamiche appare quindi un fattore cruciale per comprendere il funzionamento e eventuali fattori correttivi da apportare in sede clinica. Un fegato computazionale paziente-specifico appare quindi uno strumento estremamente utile per predire le modificazioni emodinamiche e pianificare nel futuro possibili strategie terapeutiche.
  • Characterization of Attraction Domains for Generic Quantum Semigroups
    Damiano Poletti, Politecnico di Milano
    giovedì 29 novembre 2018 alle ore 14:30 precise, Aula Seminari III piano
    ABSTRACT
    In my talk I will present the topics covered during my theses work, concerning problems linked to decoherence and asymptotic evolution of Quantum Markov Semigroups. More precisely I will introduce the subclass of Generic Quantum Semigroups and show existing results characterizing their decoherence-free subalgebra and their invariant states. Eventually I will show the results we obtained regarding attraction domains of invariant states, a topic closely related to the asymptotic behaviour of any state undergoing system evolution.
  • The Quantitative Alexandrov Theorem in Space forms
    Luigi Vezzoni, Università degli Studi di Torino
    martedì 27 novembre 2018 alle ore 15:15, Aula seminari 3° piano
    ABSTRACT
    The talk focuses on a recent generalization of a classical result of Alexandrov. The celebrated Alexandrov's Soap Bubble Theorem states that the spheres are the only closed (i.e. compact and without boundary) constant mean curvature hypersurfaces embedded in the Euclidean space. The theorem has been generalized to the hyperbolic space and to the hemisphere and to a large class of curvature operators. The main result of the talk is a quantitative version of Alexandrov's theorem which I've obtained in collaboration with Giulio Ciraolo and Alberto Roncoroni by using a quantitative study of the method of the moving planes. The theorem implies a new pinching Theorem for hypersurfaces in space forms.
  • First Principles Determination of Reaction Rates
    Carlo Cavallotti, Dipartimento di Chimica, Materiali e Ingegneria Chimica, “G. Natta”, Politecnico di Milano
    martedì 27 novembre 2018 alle ore 10:30, aula Saleri VI piano
    ABSTRACT
    The central focus of chemical kinetics is the determination of the rate at which one or more molecules react to transform into new molecules through the rearrangements of chemical bonds.
    Theoretically, chemical kinetics lies at the interface between quantum and classical mechanics, with the explicit formulation of rate laws requiring an extensive use of statistical thermodynamics.
    In the last years a priori rate calculations for gas phase reactions have undergone a gradual but dramatic transformation, with current predictions often rivaling the accuracy of the best available experimental data.
    In this seminar I will talk about the current status of ab initio chemical kinetics and of the challenges that must still be met in order to transform this branch of physical chemistry from a qualitative to a quantitative predictive science. A few example of research areas were contributions are necessary are the following: 1) the efficient determination of absolute and relative minima as well as first order saddle points on multidimensional potential energy surfaces for which gradient and, if necessary, Hessian information is available; 2) the determination of the number of energy states for a collection of non harmonic quantum oscillators; 3) the determination of a large number of eigenvalues for the quantum Hamiltonian of multidimensional rotors; 4) efficient approaches for the integration of the energy and momentum resolved master equation for chemically reactive systems.
  • Geometry and epithelial repair
    Luis Almeida , Laboratoire J-L Lions, CNRS and Sorbonne University
    martedì 27 novembre 2018 alle ore 14:00, aula Saleri VI piano
    ABSTRACT
    We will present work on the mechanisms used for establishing or restoring epithelial integrity which are motivated by experimental work on development and wound healing in Zebrafish and drosophila and on gap closure in monolayers of MDCK cells or keratinocytes. These works concern mathematical modeling of the dynamics of epithelial tissues pulled by lamellipodal crawling or the contraction of actomyosin cables at the gap boundary. We are particularly interested in the influence of the wound/gap geometry on the closure mechanism.
  • BIRATIONAL EQUIVALENCE OF ALGEBRAIC VARIETIES
    Shigefumi Mori, Kyoto University Institute of Advanced Study
    lunedì 26 novembre 2018 alle ore 16:30, Aula Chisini, Diparimento di Matematica, Via C. Saldini 50