Influence of correlations on the velocity statistics of scalar granular gases

The free evolution of inelastic particles in one dimension is studied by means of Molecular Dynamics (MD), of an inelastic pseudo-Maxwell model and of a lattice model, with emphasis on the role of spatial correlations. We present an exact solution of the 1d granular pseudo-Maxwell model for the scaling distribution of velocities and discuss how this model fails to describe correctly the homogeneous cooling stage of the 1d granular gas. Embedding the pseudo-Maxwell gas on a lattice (hence allowing for the onset of spatial correlations), we find a much better agreement with the MD simulations even in the inhomogeneous regime. This is seen by comparing the velocity distributions, the velocity profiles and the structure factors of the velocity field.Comment: Latex file: 6 pages, 5 figures (.eps). See also http://axtnt3.phys.uniroma1.it/Maxwel

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

Distant Supervised Construction and Evaluation of a Novel Dataset of Emotion-Tagged Social Media Comments in Spanish

Tagged language resources are an essential requirement for developing machine-learning text-based classifiers. However, manual tagging is extremely time consuming and the resulting datasets are rather small, containing only a few thousand samples. Basic emotion datasets are particularly difficult to classify manually because categorization is prone to subjectivity, and thus, redundant classification is required to validate the assigned tag. Even though, in recent years, the amount of emotion-tagged text datasets in Spanish has been growing, it cannot be compared with the number, size, and quality of the datasets in English. Quality is a particularly concerning issue, as not many datasets in Spanish included a validation step in the construction process. In this article, a dataset of social media comments in Spanish is compiled, selected, filtered, and presented. A sample of the dataset is reclassified by a group of psychologists and validated using the Fleiss Kappa interrater agreement measure. Error analysis is performed by using the Sentic Computing tool BabelSenticNet. Results indicate that the agreement between the human raters and the automatically acquired tag is moderate, similar to other manually tagged datasets, with the advantages that the presented dataset contains several hundreds of thousands of tagged comments and it does not require extensive manual tagging. The agreement measured between human raters is very similar to the one between human raters and the original tag. Every measure presented is in the moderate agreement zone and, as such, suitable for training classification algorithms in sentiment analysis field

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

Toward emotional interactive videogames for children with autism spectrum disorder

Technology and videogames have been proven as motivating tools for working attention and complex communication skills, especially in children with autism spectrum disorder (ASD). In this work, we present two experiences that used interactive games for promoting communication and attention. The first game considers emotions in order to measure children’s attention, concentration and satisfaction, while the second uses tangible tabletops for fostering cognitive planning. The analysis of the results obtained allows to propose a new study integrating both, in which the tangible interactive game is complemented with the emotional trainer in a way that allows identifying and classifying children’s emotion with ASD when they collaborate to solve cognitively significant and contextualized challenges. The first application proposed is an emotional trainer application in which the child can work out the seven basic emotions (happiness, sadness, fear, disgust, anger, surprise and neutral). Further, a serious videogame is proposed: a 3D maze where the emotions can be captured. The second case study was carried out in a Special Education Center, where a set of activities for working cognitive planning was proposed. In this case, a tangible interactive tabletop was used to analyze, in students with ASD, how the communication processes with these interfaces affect to the attention, memory, successive and simultaneous processing that compose cognitive planning from the PASS model. The results of the first study, suggest that the autistic children did not act with previous planning, but they used their perception to adjust their actions a posteriori (that explains the higher number of collisions). On the second case study, the successive processing was not explored. The inclusion of the mazes of case study 1 to a semantic rich scenario could allow us to measure the prior planning and the emotions involved in the maze game. The new physiological sensors will also help to validate the emotions felt by the children. The first study has as objective the capability to imitate emotions and resolve a maze without semantic context. The second study organized all the actions from a semantic context close to users. The attention results presented by the second study are coherent with the first study and complement it showing that attention can be receptive or selective. In the first study case, the receptive attention was the focus of analysis. In the second case, both contributed to explain and understand how it can be developed from a videogame

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 high energy tails in inelastic gases

We study the formation of high energy tails in a one-dimensional kinetic model for granular gases, the so-called Inelastic Maxwell Model. We introduce a time- discretized version of the stochastic process, and show that continuous time implies larger fluctuations of the particles energies. This is due to a statistical relation between the number of inelastic collisions undergone by a particle and its average energy. This feature is responsible for the high energy tails in the model, as shown by computer simulations and by analytical calculations on a linear Lorentz model.Comment: 8 pages, 2 figures, submitted to physica

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

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.

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