10:0010:40  Umberto Marini Bettolo Marconi  Università di Camerino & INFN
Dynamics of Fluids in Nanospaces
By combining methods of kinetic and density functional theory,
we present a description of molecular fluids
which accounts for their microscopic structure and thermodynamic
properties as well as for the hydrodynamic behavior.
We focus on the evolution of the one particle phase space
distribution, $f(r,v,t)$ rather than on the evolution of the average
particle density, $\rho(r,t)$,
which features in dynamic density functional theory
often employed to describe colloidal systems. In order to describe with sufficient accuracy the fluid structure at length scales comparable with the size of the particles we shall resort to methods similar to those of density functional theory (DFT) employed in the study of equilibrium and non equilibrium properties. In the case of hardcore fluids, DFT and its dynamical extension give excellent results and can be extended to more realistic fluids by using the van der Waals picture of decomposing the total interparticle potential into a shortrange repulsive potential and a longrange attractive potential tail. The first is treated by means of a reference hardsphere system whilst the second is considered within the random phase approximation (RPA). A simple analysis of the equations is used to derive explicit expressions both for equilibrium thermodynamic quantities, such as pressure, compressibility etc., and for non equilibrium transport coefficients. In the second part of our presentation we shall introduce a a multicomponent extension of our theory and describe miscible and immiscible liquid mixtures under inhomogeneous, non steady conditions typical of confined fluid flows. We first derive from a microscopic level the evolution equations of the phase space distribution function of each component in terms of a set of self consistent fields, representing both body forces and viscous forces. Secondly, we solve numerically the resulting governing equations by means of the Lattice Boltzmann method whose implementation contains novel features with respect to existing approaches. Our model incorporates hydrodynamic flow, diffusion, surface tension,and the possibility for global and local viscosity variations. We validate our model by studying the bulk viscosity dependence of the mixture on concentration, packing fraction and size ratio. Finally we consider inhomogeneous systems and study the dynamics of mixtures in slits of molecular thickness and relate structural and flow properties. The resulting equation for $f(r,v,t)$ is studied in two different physical limits: diffusive dynamics, typical of colloidal fluids without hydrodynamic interaction, where particles are subject to overdamped motion resulting from the coupling with a solvent at rest, and inertial dynamics, typical of molecular fluids . 
10:4011:00  Cesare Nardini  Università di Firenze e ENS Lyon
STOCHASTICALLY PERTURBED LONGRANGE INTERACTING SYSTEMS AND 2D FLUID
MODELS
Longrange interacting systems include neutral plasma, gravitational
systems, twodimensional and geophysical fluid models. We consider
longrange interacting systems perturbed by external stochastic forces.
Unlike the case of shortrange systems, where stochastic forces usually
act locally on each particle, here we consider perturbations by external
stochastic fields. The system reaches stationary states where the external
forces balance the dissipation on average. These states do not respect
detailed balance and support nonvanishing fluxes of conserved quantities.
I will discuss how the classical tools of kinetic theory can be extended
to describe these systems when the large structures evolve slowly.
Comparisons with numerical simulations in a case of a particularly simple
system, show an excellent agreement between the theory and simulations. I
will also discuss some results on nonequilibrium phase transitions that
we numerically observed in these systems.

11:0011:20  Aurelio Patelli, Università di Firenze
Linear response theory for long range interacting systems
Longrange interacting systems, while relaxing to equilibrium, often get
trapped in long
lived quasistationary states which have lifetimes that diverge with the
system size. In this
work, we address the question of how a longrange system in a
quasistationary state (QSS)
responds to an external perturbation. We consider a longrange system that
evolves under
deterministic Hamilton dynamics. The perturbation is taken to couple to
the canonical
coordinates of the individual constituents. Our study is based on
analyzing the Vlasov
equation for the singleparticle phase space distribution. The QSS
represents stable sta
tionary solution of the Vlasov equation in the absence of the external
perturbation. In
the presence of small perturbation, we linearize the perturbed Vlasov
equation about the
QSS to obtain a formal expression for the response observed in a
singleparticle dynami
cal quantity. We apply our analysis to a paradigmatic model, the
Hamiltonian meanﬁeld
model, that involves particles moving on a circle under Hamilton dynamics.
Our prediction
for the response of some representative QSSs in this model (the waterbag
QSS and the
Gaussian QSS) is found to be in good agreement with Nparticle simulations
for large N.

11:2011:50  pausa caffè 
11:5012:10  Samir Suweis  Università di Padova
Emerging patterns in Ecology:
the species persistencetime distributions
Natural ecosystems are characterized by striking diversity of form
and functions and yet exhibit deep symmetries emerging across
scales of space, time and organizational complexity. Speciesarea
relationships and speciesabundance distributions are examples
of emerging patterns irrespective of the details of the underlying
ecosystem functions. We present empirical and theoretical evidence
for a new macroecological pattern related to the distributions of
local species persistence times, defined as the timespans between
local colonization and extinctions in a given geographic region, and
empirically estimated from local observations of species' presence
absence time series. Empirical distributions exhibit powerlaw scaling
limited by a cutoff determined by the rate of emergence of new
species. The scaling exponents depend solely on the structure of the
spatial interaction network, regardless of the details of the ecological
interactions, suggesting similarities between ecosystem dynamics
and critical systems in physics. We also present generalize and solve
analytically a related sampling problem. The framework developed
here also allows to link the cutoff timescale with the spatial scale
of analysis, and the persistencetime distribution to the speciesarea
relationship. We conclude that the inherent coherence obtained
between spatial and temporal macroecological patterns points at a
seemingly general feature of the dynamical evolution of ecosystems.

12:1012:30  Jacopo Grilli  Università di Padova
Spatial distribution of species across scales as an emerging pattern
There has been a considerable effort to understand and quantify the
spatial distribution of species across different ecosystems. The Species
Area Relationship (SAR), which relates the area with the number of species
that it supports, is probably one of the most studied quantity in ecology.
We introduce a simple phenomenological model based on Poisson cluster
processes which allows us to derive an analytical expression for the SAR
which reproduces the empirical behavior as sample area increases from
local to continental scales, explaining how it can be understood in terms
of simple geometric arguments. Within our framework we also obtain
interesting prediction for other spatial ecological quantities.

12:3012:50  Lucia Pettinato, Università di Firenze
Spectral methods for DNA promoter analysis
Joining two different spectral methods, we are allowed to arrange the
promoters of a given species in equivalence classes, each of which is
found to be characterized by particular regular subsequences.

12:5014:40  pausa pranzo 
14:4015:20  Bernardo Spagnolo, Università di Palermo
Fluctuations and nonlinearity in classical and quantum systems
The role of interplay between noise sources and nonlinearity is
investigated in three different
classical and quantum systems.
(i) The role of a nonGaussian Lévy noise on the nonlinear
transient
dynamics of a short
overdamped Josephson junction is analyzed. The mean escape time of the
junction is investigated
considering Gaussian, CauchyLorentz and
LévySmirnov probability
distributions of the noise
signals. In these conditions we find resonant activation and the first
evidence of noise enhanced
stability in a metastable system in the presence of
Lévy
noise. For
CauchyLorentz noise source,
trapping phenomena and power law dependence on the noise intensity are
observed.
(ii) The phenomena of dissonance and consonance in a simple auditory
sensory model composed
of three neurons are considered. Two of them, here socalled sensory
neurons, are driven by noise
and subthreshold periodic signals with different ratio of frequencies, and
its outputs plus noise are
applied synaptically to a third neuron, socalled interneuron. We propose
a theoretical analysis
with a probabilistic approach to investigate the interspike intervals
(ISI) statistics of the spike train
generated by the interneuron. We find that at the output of the
interneuron, inharmonious signals
give rise to blurry spike trains, while the harmonious signals produce
more regular, less noisy, spike
trains. Theoretical results are compared with numerical simulations.
(iii) Finally the dynamics of a quantum particle subject to an asymmetric
bistable potential and
interacting with a thermal reservoir is investigated. We obtain the time
evolution of the population
distributions in the position eigenstates of the particle, for different
values of the coupling strength
with the thermal bath. The calculation is carried out by using the
FeynmanVernon functional under
the discrete variable representation.

15:2015:40  Giuseppe Luca Celardo, Università Cattolica di Brescia
Superradiance Transition in Photosynthetic LightHarvesting Complexes
We investigate the role of longlasting quantum coherence in the
efficiency of energy transport at room temperature in
FennaMatthewsOlson photosynthetic complexes. The dissipation due to
the coupling of the complex to a reaction center is analyzed using an
effective nonHermitian Hamiltonian. We show that, as the coupling to
the reaction center is varied, the maximum efficiency in energy
transport is achieved at the superradiance transition, characterized
by a segregation of the imaginary parts of the eigenvalues of the
effective nonHermitian Hamiltonian. This approach allows one to study
various couplings to the reaction center. We show that the maximal
efficiency at room temperature is sensitive to the coupling of the
system to the reaction center.

15:4016:00  Luca Guido Molinari  Università di Milano
Identities and inequalities for Transfer Matrices
General properties are presented for transfer matrices
originating from the eigenvalue equation of Hamiltonian matrices
with band structure (for example: tight binding model for crystals,
Anderson model for localization). Their eigenvalues are linked by
a spectral identity. A general statement by Demko, Moss and Smith
on the exponential decay of matrix elements of the inverse of a
band matrix, translates into statements on the matrix elements
and singular values of transfer matrices.

16:0016:20  Ettore Vitali Università degli Studi di Milano
Novel Quantum Monte Carlo techniques for the study of dynamical properties of manybody Fermi systems
Quantum Monte Carlo (QMC) techniques have become very powerful tools providing deep
insight into the
physical behaviour of strongly correlated systems. As far as equilibrium properties
of bosonic
systems are concerned, nowadays QMC simulations are able to provide "exact"
predictions.
Ordinary matter is made of fermions and dynamical properties hide plenty of physical
informations:
if one could ever achieve the accuracy that is now currently available for the
equilibrium
behavior of bosonic models, the importance for Condensed Matter Physics would be
outstanding.
For Fermi systems, it is very interesting to study approaches different from the
traditional ones
(fixed node), which may hopefully help in facing the severe challenge due to the
famous sign problem.
Here we address two novel methodologies to study dynamical properties of Fermi systems.
One relies on bosonic imaginarytime correlation functions, providing fermionic
eigenstates
as excitations over the bosonic ground state in a bigger Hilbert space, not imposing
quantum statistics [1,2]; such approach requires to pay the fee of inverting Laplace
transform in illposed
conditions. We have faced such a problem via the GIFT methodology [3]. Within this
approach,
we have studied the equation of state, the magnetic properties and the low energy
excitations of
twodimensional 3He [2,4]. We have been able to extract for the first time the zero
sound mode from
abinitio calculations, finding good agreement with experiments [5]. In principle
this methodology
provides "exact" results for energies and their derivatives; it gives access also to
a variational
estimation of dynamic structure factors. The main difficulty concernes the
extrapolation to the
thermodynamic limit.
The second approach relies on a phaseless fermionic AuxiliaryFields QMC algorithm [6].
This method is based on a random walk taking place in the Slater Determinants space,
authomatically taking into account Fermi statistics; in a "Diffusion Monte Carlo"
strategy,
the sign approximation is translated into a nonlocal and somehow weaker condition,
involving only
the overlap of one Determinant on a given guiding function, resembling the typical
importance sampling
recypes. From a formal point of view the method relies on the HubbardStratonovich
transformation.
We have preliminary results for dynamical properties of a threedimensional jellium
model.
References: [1] G. Carleo, S. Moroni, F. Becca, and S. Baroni, Phys. Rev. B 83, 060411 (2011). [2] M. Nava, E. Vitali, A. Motta, D.E. Galli, and S. Moroni, arXiv:1103.0915. [3] E. Vitali, M. Rossi, L. Reatto, and D.E. Galli, Phys. Rev. B 82, 174510 (2010). [4] M. Nava, D.E. Galli, S. Moroni, and E. Vitali, in preparation. [5] H. Godfrin, M. Meschke, H.J. Lauter, A. Sultan, H.M. Bohm, E. Krotscheck, and M. Panholzer, Nature 483, 576 (2012). [6] M. Suewattana, W. Purwanto, S. Zhang, H. Krakauer, and E.J. Walter, Phys. Rev. B 75, 245123 (2007). 
16:2016:40  Stefano Mostarda  Freiburg Institute of Advanced Studies
Complex network analysis of quantum transport
Quantum transport is deeply influenced by interference. When considering
excitation propagation through a quantum multibody system, interference
is determined by the spatial
disposition of the components.
Notwithstanding, a clear link between structure and fast, efficient transport is still missing. Here, we present a complex network analysis of quantum transport to elucidate the relationship between efficiency and structural organisation. Our analysis reveals a well defined classification related to the dynamical behaviour. 