Exact results of a mixed spin-1/2 and spin-S Ising model on a bathroom tile (4-8) lattice: effect of uniaxial single-ion anisotropy

Effect of uniaxial single-ion anisotropy upon magnetic properties of a mixed spin-1/2 and spin-S (S>=1) Ising model on a bathroom tile (4-8) lattice is examined within the framework of an exact star-triangle mapping transformation. The particular attention is focused on the phase diagrams established for several values of the quantum spin number S. It is shown that the mixed-spin bathroom tile lattice exhibits very similar phase boundaries as the mixed-spin honeycomb lattice whose critical points are merely slightly enhanced with respect to the former ones. The influence of uniaxial single-ion anisotropy upon the total magnetization vs. temperature dependence is particularly investigated as well.Comment: 12 pages, 4 figure

A comparative study of the dynamic critical behavior of the four-state Potts like models

We investigate the short-time critical dynamics of the Baxter-Wu (BW) and $n=3$ Turban (3TU) models to estimate their global persistence exponent $\theta _{g}$. We conclude that this new dynamical exponent can be useful in detecting differences between the critical behavior of these models which are very difficult to obtain in usual simulations. In addition, we estimate again the dynamical exponents of the four-state Potts (FSP) model in order to compare them with results previously obtained for the BW and 3TU models and to decide between two sets of estimates presented in the current literature. We also revisit the short-time dynamics of the 3TU model in order to check if, as already found for the FSP model, the anomalous dimension of the initial magnetization $x_{0}$ could be equal to zero

An alternative order parameter for the 4-state Potts model

We have investigated the dynamic critical behavior of the two-dimensional 4-state Potts model using an alternative order parameter first used by Vanderzande [J. Phys. A: Math. Gen. \textbf{20}, L549 (1987)] in the study of the Z(5) model. We have estimated the global persistence exponent $\theta_g$ by following the time evolution of the probability $P(t)$ that the considered order parameter does not change its sign up to time $t$. We have also obtained the critical exponents $\theta$, $z$, $\nu$, and $\beta$ using this alternative definition of the order parameter and our results are in complete agreement with available values found in literature.Comment: 6 pages, 6 figure

Correlated edge overlaps in multiplex networks

This work was partially supported by the FET proactive IP project MULTIPLEX 317532. G.J.B. was supported by the FCT Grant No. SFRH/BPD/74040/2010

The drugs misuse related harm reduction in the health promoting schools

The goal of this paper is to review the school-based drugs misuse prevention programs, and to establish a connection with the health promotion and health promoting school concepts, in an attempt to create a new proposal. There are several models of preventive intervention, but the results of its evaluations show little improvement. The most hopeful programs imply in giving up the restrict focus of prevention (of a specific disease) to adopt the health promotion concept. The application of the health promotion concept in the school environment resulted in the health promoting school concept, which can be defined as a school that has an organized set of policies, procedures, activities, and structures, designed to protect and promote the health and well-being of all school community members. The harm reduction proposal, as a prevention strategy, come together the health promoting school proposal, and in this way our proposal is a set of health promotion actions that includes: wider and progressive goals; breaking the manichaeism; inclusive actions; community partnerships including many sectors of society; youth autonomy; and the focus on the person in all its complexity, not only on the substance use or misuse. This proposal aims all students, regardless if they had or not already tried or they still are using any psychoactive substance.Este trabalho tem por objetivo revisar os modelos de prevenção do uso indevido de drogas em ambiente escolar, relacionando-os aos conceitos de promoção de saúde e escola promotora de saúde, e propor um modelo de intervenção. Os modelos de intervenção são múltiplos, os resultados provenientes das avaliações de impacto são modestos. As abordagens preventivas mais promissoras ampliam o campo de intervenções para o ambiente físico e social, enfocando a saúde como um todo, aproximando-se do conceito de promoção de saúde. A aplicação deste no âmbito escolar resultou no conceito de escola promotora de saúde. Esta pode ser definida como a escola com políticas, procedimentos, atividades e estrutura que resultem na proteção e promoção à saúde e ao bem-estar de todos os membros da comunidade escolar. A proposta da redução de danos, pensada como estratégia de prevenção, converge para a da escola promotora de saúde, e neste sentido propomos ações de promoção de saúde pautadas por: objetivos amplos e escalonados; ruptura com o maniqueísmo; ações inclusivas; parcerias intersetoriais; incentivo à autonomia dos alunos; abordagem do indivíduo em toda a sua complexidade. Esta proposta amplia a abrangência da intervenção para todos os alunos, independentemente se estes já experimentaram, já fizeram ou fazem algum uso de substâncias psicoativas.Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Departamento de PsiquiatriaUnisantos Departamento de PsiquiatriaUNIFESP, EPM, Depto. de PsiquiatriaSciEL

Post-Traumatic Stress Disorder and Urban Violence: An Anthropological Study

The study aimed to understand how distress is experienced by patients with Post-Traumatic Stress Disorder (PTSD) in the social-cultural context of São Paulo, Brazil, an urban environment marked by social inequality and high levels of violence. A qualitative study was conducted between 2008 and 2010 with PTSD patients (F43.1, ICD-10, 1997) who had been victims of robberies and kidnappings in São Paulo. Dense ethnographic observations were carried out, as well as in-depth semi-structured interviews with ten adult patients. the analysis method used was based on anthropology. the results show that it is particularly important to distinguish between perceptions of different forms of the experience of social suffering and perceptions of health and illness held by victims and biomedical experts. the cause of PTSD is more often associated with the personal problems of the victim than with the specific traumatic event. the distress described in terms of what is considered a normal reaction to violence and what is considered a symptom of PTSD. the findings indicate that the diagnostic of PTSD can be understood in relation to the different contexts within a culture. the ethnographic approach serves not only to illuminate individual suffering but also the social suffering experienced by the residents of São Paulo.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Paulo, BR-04038020 São Paulo, BrazilUniversidade Federal de São Paulo, BR-04038020 São Paulo, BrazilWeb of Scienc

The anisotropic Ashkin-Teller model: a renormalization group study

The two-dimensional ferromagnetic anisotropic Ashkin-Teller model is investigated through a real-space renormalization-group approach. The critical frontier, separating five distinct phases, recover all the known exacts results for the square lattice. The correlation length $(\nu_T)$ and crossover $(\phi)$ critical exponents are also calculated. With the only exception of the four-state Potts critical point, the entire phase diagram belongs to the Ising universality class.Comment: 3 ps figures, accepted for publication in Physica

Machine learning approach for computing optical properties of a photonic crystal fiber

Photonic crystal fibers (PCFs) are the specialized optical waveguides that led to many interesting applications ranging from nonlinear optical signal processing to high-power fiber amplifiers. In this paper, machine learning techniques are used to compute various optical properties including effective index, effective mode area, dispersion and confinement loss for a solid-core PCF. These machine learning algorithms based on artificial neural networks are able to make accurate predictions of above-mentioned optical properties for usual parameter space of wavelength ranging from 0.5-1.8 µm, pitch from 0.8-2.0 µm, diameter by pitch from 0.6-0.9 and number of rings as 4 or 5 in a silica solid-core PCF. We demonstrate the use of simple and fast-training feed-forward artificial neural networks that predicts the output for unknown device parameters faster than conventional numerical simulation techniques. Computation runtimes required with neural networks (for training and testing) and Lumerical MODE solutions are also compared

The Ferromagnetic Potts model under an external magnetic field: an exact renormalization group approach

The q-state ferromagnetic Potts model under a non-zero magnetic field coupled with the 0^th Potts state was investigated by an exact real-space renormalization group approach. The model was defined on a family of diamond hierarchical lattices of several fractal dimensions d_F. On these lattices, the renormalization group transformations became exact for such a model when a correlation coupling that singles out the 0^th Potts state was included in the Hamiltonian. The rich criticality presented by the model with q=3 and d_F=2 was fully analyzed. Apart from the Potts criticality for the zero field, an Ising-like phase transition was found whenever the system was submitted to a strong reverse magnetic field. Unusual characteristics such as cusps and dimensional reduction were observed on the critical surface.Comment: 8 pages, 6 figures. Accepted to be published in Phys. Rev B (2006

Exact relations between damage spreading and thermodynamic functions for the N-color Ashkin-Teller model

Exact results are derived relating quantities computable by the so-called damage spreading method and thermodynamic functions for the N-color Ashkin-Teller model. The results are valid for any ergodic dynamics. Since we restrict our analysis to the ferromagnetic case the results are also valid for any translational invariant lattice. The derived relations should be used in order to determine numerically the N-color Ashkin-Teller critical exponents with better accuracy and less computational efforts than standard Monte Carlo simulations.Comment: 6 pages, to be published in JSTAT (Journal of Statistical Mechanics: Theory and Experiment). The results of a computer simulation were included for N=3 as an example on how to use the analytical relations derived in the paper as a guide to obtain the critical temperature and critical exponent