Evaluation of future climate scenario by means of global and local scale models: impacts and adaptation actions

Climate change is now a irrefutable reality. The last IPCC report of September 2013 showed again how Climate has already changed in the past at the global and local scales, and as this trend could continue in the future, in a more or less marked way, depending of the scenarios of emission of greenhouse gases, caused by different future scenarios of society development. For the assessment of future climate scenarios, the use of ocean-atmosphere global climate models (AOGCM), of regional climate models (RCMs) and of statistical downscaling of AOGCM outputs is now consolidated. This modeling chain is able to produce climatic scenarios at local scales, from which it is possible to evaluate impacts on ecosystems and the human activities as, for example, agriculture, health, tourism, hydrological risk, water resources etc. In order to mitigate these impacts it is necessary to operate in two directions: 1) reduce the "causes" of climate change, i.e. reduce the greenhouse gas emissions. At the same time, 2), it is necessary also to devise adaptation actions in order to reduce the damages produced by the impacts of climate change. In this seminar I will make a brief review of the state of the art of climate modeling at global and regional scales, highlighting the now irrefutable certainties and, on the contrary, where and why uncertainties still exist. Finally, the main impacts of climate change will be described for the mediterranean area and some "hard" and "soft" adaptation actions and policies will be described for the different sectors.

Friday, 17 July 2015, ore 14:30 — Sala Wataghin

Jefferson-Lab Science: Present and Future

The continuous electron beam accelerator facility at Jefferson Lab, built with advanced superconducting radiofrequency (SRF) technology, provides opportunities to discover fundamental new aspects of the structure of visible matter, protons, neutrons and other bound states, and of the strong interaction, described by the gauge theory Quantum Chromodynamics. Jefferson Lab's accelerator, in operation since 1995, is unique in the world and is currently undergoing a major upgrade to double its energy. The upgrade will bring new opportunities, not only in the study of hadronic matter, but also in searches for new physics, such as a suite of experiments to search for massive `dark photons'. For the future, we are developing a plan for a new facility, an Electron Ion Collider.

Tuesday, 23 June 2015, ore 14:30 — Sala Wataghin

Manipulating the flavours of real and artificial graphene

In this talk I will first discuss some general aspects of the electronic and mechanical properties of graphene membranes. I will present different strain- induced effects in mono- and bi-layer graphene, describing how elastic deformations in the lattice translate into fictitious vector potentials that affect the electronic degrees of freedom. I will analyse the consequences on quantum transport in ballistic devices and extend this concept to artificial graphene systems, such as honeycomb plasmonic arrays of metallic nanoparticles. In the latter metasurfaces I will show that plasmons behave as massless Dirac particles with a highly tunable bandstructure.

Monday, 15 June 2015, ore 14:30 — Sala Wataghin

Dalle disuguaglianze di Bell alla crittografia quantistica

La meccanica quantistica è una delle più sorprendenti e rivoluzionarie scoperte del secolo scorso. Tra le sue controintuitive predizioni si possono ricordare la funziona d'onda, il principio di indeterminazione, il dualismo onda-particella, la sovrapposizione di stati quantistici, l'entanglement e le disuguaglianze di Bell. Tali predizioni sono state verificate in innumerevoli esperimenti e sono oggi alla base dell'Informazione Quantistica (QI), che studia la possibilità di manipolare e trasmettere l'informazione in maniera totalmente innovativa rispetto alle tecniche concesse dalla fisica classica. Dopo una breve introduzione ai concetti fondamentali della meccanica quantistica, saranno presentate alcune delle sue applicazioni nella QI, come la crittografia quantistica (Quantum Key Distribution), la generazione di numeri casuali genuini e il teletrasporto quantistico.

Friday, 5 June 2015, ore 14:30 — Sala Wataghin

Beam Physics Research-and-Development for Future Particle Accelerators

The latest challenges and achievements in particle accelerator R&D will be presented: high-gradient acceleration, impedance control, beam-based optimization, luminosity performance are some of the challenges that particle accelerators for the post-LHC era must address. The talk will start from a description of the Compact Linear Collider (CLIC) Study at CERN to illustrate these concepts. CLIC is an electron-positron linear collider with a centre-of-mass energy of 3 TeV under development at CERN to allow precise measurements of the Higgs boson, as well as a multitude of searches for New Physics. A summary of the concept, progress and status of the corresponding studies in Accelerator R&D will be given, as well as an outline of the preparation work toward the implementation.

Friday, 22 May 2015, ore 14:30 — Sala Wataghin

Enrico Fermi and the birth of non-linear physics

In the early fifties in Los Alamos E. Fermi in collaboration with J. Pasta and S. Ulam started investigating what they assumed would be a very simple nonlinear mechanical system, i.e. a one dimensional chain of equal masses connected by a weakly nonlinear spring. The key question was related to the understanding of the phenomenon of conduction in solids; in particular they wanted to estimate the time needed to reach a statistical equilibrium state characterized by the equipartition of energy among the normal modes. They approached the problem numerically using the MANIAC I computer; however, the system did not thermailize and they observed a recurrence to the initial condition (this is known as the FPU-recurrence). This unexpected (and unexplained) result has lead to the development of the modern nonlinear physics (discovery of solitons and integrability). In this colloquium, I will give an historical overview of the subject and present the different approaches that have been proposed in the last 60 years for explaining this paradox. Very recent results on the estimation of the time scale and on the mechanism of equipartition will also be reported and discussed.

Friday, 8 May 2015, ore 14:30 — Sala Wataghin

Latching dynamics and the glassy nature of linguistic representations

In our group we have explored latching dynamics in Potts neural networks as a simplified model of spontaneous production, for example of sentences. In departing from the simplest network realization towards approaching the complexity of real languages, however, we have encountered the major effect of correlations and of the resulting disorder-dominated dynamics, which call for the refinement and application of statistical physics tools to linguistic data.

Friday, 24 April 2015, ore 14:30 — Sala Wataghin

QCD and collider physics

Physics at hadron colliders, and in particular at the LHC, requires a rather detailed understanding of strong interactions at high energies. In this seminar I will review the physics of large transverse momentum processes at colliders, the methods used to compute cross sections and simulate collision events, and the current theoretical developments and perspectives.

Friday, 17 April 2015, ore 14:30 — Sala Wataghin

How well can we describe properties of the Quark-Gluon plasma?

In the first part of the colloquium I will present two concepts of the quark-gluon plasma: first as an asymptotic state of strong interactions (achieved at extreme temperatures and/or densities), second as a new state of matter established experimentally in heavy-ion collisions. Then, I will turn to the discussion of relativistic hydrodynamics and its role in the determination of properties of that new phase. Finally, I will present recent developments of dissipative relativistic hydrodynamics, comparing various computational schemes with the predictions of the underlying kinetic theory.

Friday, 27 March 2015, ore 14:30 — Sala Wataghin

Indirect searches for WIMP dark matter: a few signal candidates and many constraints

Despite the enormous success of astrophysical and cosmological research over the last decades, about 85% of the matter content in the Universe remains unknown. The currently leading hypothesis for this so-called dark matter are Weakly Interacting Massive Particles (WIMPs). Strategies for the identification of WIMPs range from searches with particle colliders to searches with underground low-background experiments. I will here focus on a third approach: Indirect searches for self-annihilation products of WIMPs in the gamma-ray and cosmic-ray sky. I will review existing constraints and signal candidates that were discussed in the recent literature. Emphasize will be given to a diffuse extended excess emission that is seen from the Galactic center in gamma-ray bservations with the Fermi Large Area Telescope. It has all the properties expected for a dark matter annihilation signal. Although it would be too premature to claim a discovery yet, it is an excellent example for the challenges and techniques, but also opportunities, of indirect dark matter searches in the near future.

Friday, 13 March 2015, ore 14:30 — Sala Wataghin