Velocity Tails for Inelastic Maxwell Models

We study the velocity distribution function for inelastic Maxwell models, characterized by a Boltzmann equation with constant collision rate, independent of the energy of the colliding particles. By means of a nonlinear analysis of the Boltzmann equation, we find that the velocity distribution function decays algebraically for large velocities, with exponents that are analytically calculated.Comment: 4 pages, 2 figure

Velocity fluctuations in a one dimensional Inelastic Maxwell model

We consider the velocity fluctuations of a system of particles described by the Inelastic Maxwell Model. The present work extends the methods, previously employed to obtain the one-particle velocity distribution function, to the study of the two particle correlations. Results regarding both the homogeneous cooling process and the steady state driven regime are presented. In particular we obtain the form of the pair correlation function in the scaling region of the homogeneous cooling process and show that some of its moments diverge. This fact has repercussions on the behavior of the energy fluctuations of the model.Comment: 16 pages, 1 figure, to be published on Journal of Statistical Mechanics: Theory and Experiment

The Role of Trauma in Early Onset Borderline Personality Disorder: A Biopsychosocial Perspective

The role of childhood trauma in the development of borderline personality disorder (BPD) in young age has long been studied. The most accurate theoretical models are multifactorial, taking into account a range of factors, including early trauma, to explain evolutionary pathways of BPD. We reviewed studies published on PubMed in the last 20 years to evaluate whether different types of childhood trauma, like sexual and physical abuse and neglect, increase the risk and shape the clinical picture of BPD. BPD as a sequela of childhood traumas often occurs with multiple comorbidities (e.g. mood, anxiety, obsessive-compulsive, eating, dissociative, addictive, psychotic, and somatoform disorders). In such cases it tends to have a prolonged course, to be severe, and treatment-refractory. In comparison with subjects who suffer from other personality disorders, patients with BPD experience childhood abuse more frequently. Adverse childhood experiences affect different biological systems (HPA axis, neurotransmission mechanisms, endogenous opioid systems, gray matter volume, white matter connectivity), with changes persisting into adulthood. A growing body of evidence is emerging about interaction between genes (e.g. FKBP5 polymorphisms and CRHR2 variants) and environment (physical and sexual abuse, emotional neglect)

On the out of equilibrium order parameters in long-range spin-glases

We show that the dynamical order parameters can be reexpressed in terms of the distribution of the staggered auto-correlation and response functions. We calculate these distributions for the out of equilibrium dynamics of the Sherrington-Kirpatrick model at long times. The results suggest that the landscape this model visits at different long times in an out of equilibrium relaxation process is, in a sense, self-similar. Furthermore, there is a similarity between the landscape seen out of equilibrium at long times and the equilibrium landscape. The calculation is greatly simplified by making use of the superspace notation in the dynamical approach. This notation also highlights the rather mysterious formal connection between the dynamical and replica approaches.Comment: 25 pages, Univ. di Roma I preprint #1049 (we replaced the file by the RevTex file, figures available upon request

Analytical results for generalized persistence properties of smooth processes

We present a general scheme to calculate within the independent interval approximation generalized (level-dependent) persistence properties for processes having a finite density of zero-crossings. Our results are especially relevant for the diffusion equation evolving from random initial conditions, one of the simplest coarsening systems. Exact results are obtained in certain limits, and rely on a new method to deal with constrained multiplicative processes. An excellent agreement of our analytical predictions with direct numerical simulations of the diffusion equation is found.Comment: 21 pages, 4 figures, to appear in Journal of Physics

Characteristics of neonatal GBS disease during a multicentre study (2007-2010) and in the year 2012

iNTRODUCTION: The characteristics of Group B Streptococcal (GBS) early onset (EOD) and late onset (LOD) neonatal infections in Italy were analyzed. Two periods were considered, a first 3-years period (2007-2010), when notification of GBS infections was enforced under the auspices of the Italian Ministry of Health, and a second 1 year period (2012) when reporting on neonatal GBS disease continued on voluntary basis. METHODS: A standardized form was used to collect data on cases of neonatal GBS disease. They included both maternal and neonatal data. RESULTS AND DISCUSSION: The two surveys underlined that preterm deliveries, precipitous labor and negatively GBS screened mothers are common causes of EOD occurrence, possibly explained by inadequate, or lack of, intrapartum antibiotic prophylaxis. Nevertheless, measures for reducing prevention failures and EOD incidence by an higher adherence to prevention strategies, as the Centre for Disease Control recommendations, are still possible and should be encouraged

Average trajectory of returning walks

We compute the average shape of trajectories of some one--dimensional stochastic processes x(t) in the (t,x) plane during an excursion, i.e. between two successive returns to a reference value, finding that it obeys a scaling form. For uncorrelated random walks the average shape is semicircular, independently from the single increments distribution, as long as it is symmetric. Such universality extends to biased random walks and Levy flights, with the exception of a particular class of biased Levy flights. Adding a linear damping term destroys scaling and leads asymptotically to flat excursions. The introduction of short and long ranged noise correlations induces non trivial asymmetric shapes, which are studied numerically.Comment: 16 pages, 16 figures; accepted for publication in Phys. Rev.

Steady state properties of a mean field model of driven inelastic mixtures

We investigate a Maxwell model of inelastic granular mixture under the influence of a stochastic driving and obtain its steady state properties in the context of classical kinetic theory. The model is studied analytically by computing the moments up to the eighth order and approximating the distributions by means of a Sonine polynomial expansion method. The main findings concern the existence of two different granular temperatures, one for each species, and the characterization of the distribution functions, whose tails are in general more populated than those of an elastic system. These analytical results are tested against Monte Carlo numerical simulations of the model and are in general in good agreement. The simulations, however, reveal the presence of pronounced non-gaussian tails in the case of an infinite temperature bath, which are not well reproduced by the Sonine method.Comment: 23 pages, 10 figures, submitted for publicatio

Guidelines to design tangible tabletop activities for children with attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder is one of the most frequent neurodevelopmental disorders among children. In spite of this, there is a lack of HCI research specifically devoted to these children. This paper describes efforts to transfer previous experience with other neurodiverse children in the field of tangible tabletops to ADHD children. The results of evaluation sessions carried out in conjunction with an ADHD association, complemented with an in-depth study of their special characteristics and needs, have led to a set of guidelines oriented to the design of tangible tabletop activities. These guidelines are mostly general and applicable to the design of any interactive application oriented to ADHD children. They are also appropriate for applications for other neurodiverse children or, in fact, any child from a more inclusive perspective

Web-gis storico-archeologico della Val di Vara

The “Tra Monti” project concerns a set of Municipalities in “Val di Vara” (La Spezia, IT). The goal is to collect archeological and architectural data about the area of study, as well as to build a sort of “oral memory” in order to promote the cultural heritage of the area and for scientific purposes. The director of the project is the University of Pisa which has promoted a collaboration between historical, archeological and IT experts. A devasting flood just during the activity, which destroyed cultural goods documented some days before, stressed the goal of the project. We designed and build a web site to manage and publish the information we collected. The web site uses only OS and Free SW components; some web 2.0 functions are available and an important GIS part is present. The spirit of the project is sympathetic to the actual technological context, whose opportunities suggest to consider the territory as a mix of “objects” and “people”. Both experts in the universities and local people on the territory can give a contribution in enriching the DataBase with new data and a knowledge contribution with their different particular skills