The Fundamental Concepts of Classical Equilibrium Statistical Mechanics

A critical examination of some basic conceptual issues in classical statistical mechanics is attempted, with a view to understanding the origins, structure and statuts of that discipline. Due attention is given to the interplay between physical and mathematical aspects, particularly regarding the role of probability theory. The focus is on the equilibrium case, which is currently better understood, serving also as a prelude for a further discussion of non-equilibrium statistical mechanics.Comment: 33 pages, overview, conceptual discussio

Driven Tracer Particle and Einstein Relation in One Dimensional Symmetric Simple Exclusion Process

We investigate the behavior of a tagged particle under the action of an external constant driving force in an infinite system of particles evolving in a one dimensional lattice according to symmetric random walks with hard core interaction

Cidade e memória

Cidade e Memória é um curta-documentário que busca resgatar um pouco da história da cidade do Rio de Janeiro através das memórias de um homem. Guiado por sua filha, refazemos com ele o caminho que costumava trilhar de sua casa no bairro do Maracanã até sua escola em São Cristóvão e levados por suas palavras, embarcamos em uma viagem no tempo

Emotional and attitudinal evaluation of tobacco health warnings among youngsters and adults in Argentina

Objective. To evaluate variables of tobacco health warnings associated with their emotional impact, the perception of smoking risks and the perceived effectiveness to avoid tobacco use. Materials and methods. Teenagers (151) andadults (168) evaluated 27 tobacco health warnings selected from the sets used on tobacco packages in Argentina and in other countries. A standardized affective rating-scale system and a structured questionnaire measured respectively the emotional impact (hedonic valence and emotional arousal), and the cognitive-behavioral attributions. The correlation between emotional and cognitive-behavioral evaluations was analyzed by age, sex, education level, smoker status, stage of quitting and susceptibility of non-smokers teenagers. Results. Strong significant correlations between cognitivebehavioral and emotional assessments were observed. The warnings depicting graphic images of tobacco-related injuries and suffering were considered more valuable for tobacco control, helping quitting and preventing initiation. Conclusions. Using graphic images with high emotional arousal is recommended for both adults and teenagers

Decoding negative affect personality trait from patterns of brain activation to threat stimuli

INTRODUCTION: Pattern recognition analysis (PRA) applied to functional magnetic resonance imaging (fMRI) has been used to decode cognitive processes and identify possible biomarkers for mental illness. In the present study, we investigated whether the positive affect (PA) or negative affect (NA) personality traits could be decoded from patterns of brain activation in response to a human threat using a healthy sample. METHODS: fMRI data from 34 volunteers (15 women) were acquired during a simple motor task while the volunteers viewed a set of threat stimuli that were directed either toward them or away from them and matched neutral pictures. For each participant, contrast images from a General Linear Model (GLM) between the threat versus neutral stimuli defined the spatial patterns used as input to the regression model. We applied a multiple kernel learning (MKL) regression combining information from different brain regions hierarchically in a whole brain model to decode the NA and PA from patterns of brain activation in response to threat stimuli. RESULTS: The MKL model was able to decode NA but not PA from the contrast images between threat stimuli directed away versus neutral with a significance above chance. The correlation and the mean squared error (MSE) between predicted and actual NA were 0.52 (p-value=0.01) and 24.43 (p-value=0.01), respectively. The MKL pattern regression model identified a network with 37 regions that contributed to the predictions. Some of the regions were related to perception (e.g., occipital and temporal regions) while others were related to emotional evaluation (e.g., caudate and prefrontal regions). CONCLUSION: These results suggest that there was an interaction between the individuals' NA and the brain response to the threat stimuli directed away, which enabled the MKL model to decode NA from the brain patterns. To our knowledge, this is the first evidence that PRA can be used to decode a personality trait from patterns of brain activation during emotional contexts

Impact of Cognitive Behavioral Therapy on Resting Cardiac Parameters and Cortisol in Patients with Post-Traumatic Stress Disorder: A Pilot Randomized Clinical Trial

Post-Traumatic Stress Disorder (PTSD) has been associated with changes in psychophysiological and neuroendocrinal parameters. Cognitive Behavioral Therapy (CBT) is considered the treatment of choice for PTSD and is able to regularize altered neurobiological parameters; however, little is known about its effects on these parameters when measured during the therapeutic process. This pilot study aimed to evaluate the impact of CBT on cortisol and cardiac parameters measured at rest during the treatment of PTSD with comorbid major depression. 14 patients were randomized to four months of CBT or a waiting list. As expected, the experimental group had a greater reduction in PTSD symptoms and a large effect size. There was a reduction in the low frequency component of heart rate variability, which achieved borderline statistical significance and a large effect size. Salivary cortisol tended to track the progress of therapy, rising in the period of exposure and decreasing by the end of treatment. Despite the small sample size, this study opens the way for further research into the impact of CBT on the different biological markers of PTSD during the therapeutic process. This can hopefully help to optimize and personalize therapeutic studies while providing clues about modifications in bio behavioral pathological manifestations

Vulnerability and Protective Factors for PTSD and Depression Symptoms Among Healthcare Workers During COVID-19: A Machine Learning Approach

Background: Healthcare workers are at high risk for developing mental health problems during the COVID-19 pandemic. There is an urgent need to identify vulnerability and protective factors related to the severity of psychiatric symptoms among healthcare workers to implement targeted prevention and intervention programs to reduce the mental health burden worldwide during COVID-19. // Objective: The present study aimed to apply a machine learning approach to predict depression and PTSD symptoms based on psychometric questions that assessed: (1) the level of stress due to being isolated from one's family; (2) professional recognition before and during the pandemic; and (3) altruistic acceptance of risk during the COVID-19 pandemic among healthcare workers. // Methods: A total of 437 healthcare workers who experienced some level of isolation at the time of the pandemic participated in the study. Data were collected using a web survey conducted between June 12, 2020, and September 19, 2020. We trained two regression models to predict PTSD and depression symptoms. Pattern regression analyses consisted of a linear epsilon-insensitive support vector machine (ε-SVM). Predicted and actual clinical scores were compared using Pearson's correlation coefficient (r), the coefficient of determination (r2), and the normalized mean squared error (NMSE) to evaluate the model performance. A permutation test was applied to estimate significance levels. // Results: Results were significant using two different cross-validation strategies to significantly decode both PTSD and depression symptoms. For all of the models, the stress due to social isolation and professional recognition were the variables with the greatest contributions to the predictive function. Interestingly, professional recognition had a negative predictive value, indicating an inverse relationship with PTSD and depression symptoms. // Conclusions: Our findings emphasize the protective role of professional recognition and the vulnerability role of the level of stress due to social isolation in the severity of posttraumatic stress and depression symptoms. The insights gleaned from the current study will advance efforts in terms of intervention programs and public health messaging