Global Free-Energy Landscapes as a Smoothly Joined Collection of Local Maps.

Enhanced sampling techniques have become an essential tool in computational chemistry and physics, where they are applied to sample activated processes that occur on a time scale that is inaccessible to conventional simulations. Despite their popularity, it is well known that they have constraints that hinder their application to complex problems. The core issue lies in the need to describe the system using a small number of collective variables (CVs). Any slow degree of freedom that is not properly described by the chosen CVs will hinder sampling efficiency. However, the exploration of configuration space is also hampered by including variables that are not relevant for the activated process under study. This paper presents the Adaptive Topography of Landscape for Accelerated Sampling (ATLAS), a new biasing method capable of working with many CVs. The root idea of ATLAS is to apply a divide-and-conquer strategy, where the high-dimensional CVs space is divided into basins, each of which is described by an automatically determined, low-dimensional set of variables. A well-tempered metadynamics-like bias is constructed as a function of these local variables. Indicator functions associated with the basins switch on and off the local biases so that the sampling is performed on a collection of low-dimensional CV spaces that are smoothly combined to generate an effectively high-dimensional bias. The unbiased Boltzmann distribution is recovered through reweighing, making the evaluation of conformational and thermodynamic properties straightforward. The decomposition of the free-energy landscape in local basins can be updated iteratively as the simulation discovers new (meta)stable states.

Iterative Unbiasing of Quasi-Equilibrium Sampling.

Atomistic modeling of phase transitions, chemical reactions, or other rare events that involve overcoming high free energy barriers usually entails prohibitively long simulation times. Introducing a bias potential as a function of an appropriately chosen set of collective variables can significantly accelerate the exploration of phase space, albeit at the price of distorting the distribution of microstates. Efficient reweighting to recover the unbiased distribution can be nontrivial when employing adaptive sampling techniques such as metadynamics, variationally enhanced sampling, or parallel bias metadynamics, in which the system evolves in a quasi-equilibrium manner under a time-dependent bias. We introduce an iterative unbiasing scheme that makes efficient use of all the trajectory data and that does not require the distribution to be evaluated on a grid. The method can thus be used even when the bias has a high dimensionality. We benchmark this approach against some of the existing schemes on model systems with different complexity and dimensionality.

Cross validation of the factor structure of the 20-item Toronto Alexithymia Scale: an Italian multicenter study.

The 20-item Toronto Alexithymia Scale (TAS-20) has been shown in previous research to measure a general dimension of alexithymia with three intercorrelated factors. This study evaluated the reliability and factorial validity of an Italian translation of the TAS-20 in a group of normal adults (N = 206) and in a mixed group of medical and psychiatric outpatients (N = 642). Using confirmatory factor analyses, the previously established three-factor model of the TAS-20 was found to be replicable in both groups. In addition, the Italian TAS-20 demonstrated adequate estimates of internal reliability and test-retest reliability. Although evaluation of the convergent, discriminant, and concurrent validity of the TAS-20 is required in Italian populations, the present results support the use of the Italian translation of the scale for clinical and research purposes.

[Medical students and psychiatry. A survey of students' opinion]. / Studenti di medicina e psichiatria. Osservazioni da un sondaggio di opinione.

In the last years research on the didactics of Psychiatry and opinions of medical students on Psychiatry has gained great interest. The authors think that this research could be useful for the improvement of didactics, for better understanding the meanings of professional choice, the identity of psychiatrist and their relationship with colleagues in other medical field. The goal of this research work was a preliminary survey of Genoese University Medical Student's opinions about psychiatry didactics, and choice of specialization. A questionnaire was submitted to all the students who passed Clinical Psychiatry examination in the period from November 1987 to December 1988. The students were divided in two randomized groups: the first group of students (224) was submitted to the questionnaire immediately after Clinical Psychiatry examination; while to the second group of students (66) the questionnaire was mailed. The aim of the questions was to assess the student's opinions on psychiatry, psychoanalysis, psychotherapy, the career they wanted to take up, and the difficulties of studying psychiatry: 69% of the students of the first group and 42% of the students of the second group answered the questionnaire. Female students answered that they preferred psychiatric specialization more than their male colleagues did, but the difference has no statistical importance. In most cases, the students who answered that they have taken into account psychiatry as a choice of specialisation, are more interested in medical specialties (primary care, etc.) than in surgical specialties. Most of the medical students declare some emotional troubles (anxiety, sleeplessness, problem in social relations).(ABSTRACT TRUNCATED AT 250 WORDS)

[Psychiatric (psychodynamic and psychotherapeutic) aspects of obesity]. / Aspetti psichiatrici (psicodinamici e psicoterapeutici) dell'obesità.

An account is given for non-psychiatric physicians of the psychodynamic, psychiatric, and psychoterapeutic aspects of obesity. A primarily psychoanalytic explanation is presented of the unconscious meanings that the words involved assume in children and "fixed" obese subjects with regression to the "oral stage" of their libido development. The meanings associated with food and feeding are examined in an interpersonal, familial, social and environmental context. A summary psychopathological classification is made of obesity, together with an evaluation of what appears to be the direct opposite of obesity, i. e. mental anorexia. Lastly, the relevant prognostic and therapeutic criteria are considered. The latter are mainly centred on the various forms of psychotherapeutic intervention (individual, group, analytical and inspiration therapy, etc.).