Finite-size, magnetic and chemical-potential effects on first-order phase transitions

We perform a study about effects of an applied magnetic field and a finite chemical potential on the size-dependent phase structure of a first-order transition. These effects are introduced by using methods of quantum fields defined on toroidal spaces, and we study in particular the case of two compactified dimensions, imaginary time and a spatial one (a heated film). It is found that for any value of the applied field, there is a minimal size of the system, independent of the chemical potential, below which the transition disappears.Comment: 19 pages, 3 figures, version accepted for publication in Phys. Lett.

Modelo de argumentação na análise da qualidade de apresentações orais de alunos de química sobre o tema

Este trabalho trata de uma atividade didática aplicada no ensino de Química na qual os alunos solucionaram casos investigativos e argumentaram a favor do uso de ligas e de revestimentos protetores aplicáveis em determinados materiais de forma a evitar a sua corrosão. As apresentações orais dos alunos sobre as soluções encontradas para um dos casos foram analisadas tendo em vista a determinação da qualidade dos argumentos usados nas mesmas. Apenas parte dos alunos desenvolveu argumentos fortes nas justificativas das soluções escolhidas para o caso e o Modelo de Argumentação de Takao e Kelly, adotado como referencial teórico, mostrou-se adequado para aplicação em disciplinas de Química nas quais se deseje avaliar a capacidade argumentativa dos alunos

Modelo de argumentação na análise da qualidade de apresentações orais de alunos de química sobre o tema

Este trabalho trata de uma atividade didática aplicada no ensino de Química na qual os alunos solucionaram casos investigativos e argumentaram a favor do uso de ligas e de revestimentos protetores aplicáveis em determinados materiais de forma a evitar a sua corrosão. As apresentações orais dos alunos sobre as soluções encontradas para um dos casos foram analisadas tendo em vista a determinação da qualidade dos argumentos usados nas mesmas. Apenas parte dos alunos desenvolveu argumentos fortes nas justificativas das soluções escolhidas para o caso e o Modelo de Argumentação de Takao e Kelly, adotado como referencial teórico, mostrou-se adequado para aplicação em disciplinas de Química nas quais se deseje avaliar a capacidade argumentativa dos alunos

An analysis of landscape fragmentation in the Brazilian Amazon based on deforestation data derived from Landsat imagery.

Deforestation in the Brazilian Amazon has produced fragmentation of the largest tropical rain forest in the planet resulting in impacts over biodiversity and the functioning of ecosystems. Most of the deforestation is known to be concentrated near major roads and areas of pioneer colonization, but few studies have quantitatively analyzed patterns and processes of landscape fragmentation associated with this spatial dynamics. In this paper we evaluate the effect of forest clearing based on two landscape metrics - percent cleared and percolation - for areas in the states of Mato Grosso, Pará, and Rondônia where the largest rates of deforestation have been observed. Deforestation data included one data set derived from Landsat MSS imagery for the 1970?s and one based on Landsat TM imagery for 2006. Forest fragments in 2006 within 25-km of areas deforested since 1978 - where a large majority of recent deforestation has been concentrated - were analyzed to assess how landscape fragmentation has evolved following the diffusion of forest clearing within a relatively close neighborhood of the 1978 deforestation. The distribution of deforestation for regular ¼-degree grid cells with different values of percent cleared was estimated as a proxy for the distribution of the equivalent metric based on actual farm limits. The fractions of deforestation for larger categories of percent cleared have increased during the diffusion of forest clearing and a majority of the total 2006 deforestation belonged to areas with less than 50% of forest remnants, taking as reference the Brazilian forest regulations. The diffusion of deforestation has resulted in different patterns of landscape fragmentation based on estimated percolation and we propose an analysis of such patterns based on geographic differences

Effect of age and anatomic site on likelihood of detecting S. aureus in pigs

Intensive sampling of two swine farms in Minnesota was conducted to obtain basic information about the ecology and epidemiology of S. aureus in modern multiple site swine production. The farms were selected by convenience, and two cohorts of animals were sampled in each system

Assistência pré-natal no Sul do Brasil: cobertura, tendência e disparidades

OBJECTIVE: To estimate coverage, examine trend and assess the disparity reduction regarding household income during prenatal care between mothers living in Rio Grande, state of Rio Grande do Sul, in 2007, 2010, 2013 and 2016. METHODS: This study included all recent mothers living in this municipality, between 1/1 and 12/31 of those years, who had a child weighing more than 500 grams or 20 weeks of gestational age in one of the only two local maternity hospitals. Trained interviewers applied, still in the hospital and up to 48 hours after delivery, a unique and standardized questionnaire, seeking to investigate maternal demographic and reproductive characteristics, the socioeconomic conditions of the family and the assistance received during pregnancy and childbirth. To assess the adequacy of prenatal care, the criteria proposed by Takeda were used, which considers only the number of prenatal appointments and gestational age at initiation, and by Silveira et al., who in addition to these two variables, considers the achievement of some laboratory tests. Chi-square tests were used to compare proportions and assess the linear trend. RESULTS: The total of 10,669 recent mothers were included in this survey (96.8% of the total). Prenatal coverage substantially increased between 2007 and 2016. According to Takeda, it rose from 69% to 80%, while for Silveira et al., it increased from 21% to 55%. This improvement occurred for all income groups (p < 0.01). The disparity between the extreme categories of income reduced, according to Takeda, and increased according to Silveira et al. CONCLUSIONS: The provision of prenatal care, considering only the number of appointments and the early start, occurred in greater proportion among the poorest. However, only the richest recent mothers were contemplated with more elaborate care, such as laboratory tests, which increased the disparities in the provision of prenatal care.OBJETIVO: Estimar a cobertura, examinar a tendência e avaliar se houve redução da disparidade em relação à renda familiar na realização de pré-natal adequado entre puérperas residentes em Rio Grande, RS, nos anos de 2007, 2010, 2013 e 2016. MÉTODOS: Foram incluídas neste estudo todas as puérperas residentes nesse município que, entre 1/1 a 31/12 desses anos, tiveram filho com peso superior a 500 gramas ou 20 semanas de idade gestacional em alguma das duas únicas maternidades locais. Entrevistadoras treinadas aplicaram, ainda no hospital e em até 48 horas após o parto, questionário único e padronizado, buscando investigar as características demográficas e reprodutivas maternas, as condições socioeconômicas da família e a assistência recebida durante a gestação e parto. Para avaliação da adequação do pré-natal, foram utilizados os critérios propostos por Takeda, que considera apenas o número de consultas pré-natais e a idade gestacional de início, e de Silveira et al., que além dessas duas variáveis, leva em conta a realização de alguns testes laboratoriais. Foram utilizados os testes qui-quadrado para comparar proporções e avaliar tendência linear. RESULTADOS: Foram incluídas neste inquérito 10.669 puérperas (96,8% do total). Verificou-se substancial aumento na cobertura de pré-natal adequado entre 2007 e 2016. Segundo Takeda, passou de 69% para 80%, enquanto para Silveira et al. aumentou de 21% para 55%. Essa melhora no período ocorreu para todos os grupos de renda (p < 0,01). Houve redução na disparidade entre as categorias extremas de renda segundo Takeda e aumento acentuado segundo Silveira et al. CONCLUSÕES: A oferta de pré-natal, considerando apenas o número de consultas e o início precoce, ocorreu em maior proporção entre as mais pobres. No entanto, ao oferecer cuidados mais elaborados, como exames laboratoriais, estes alcançaram principalmente as puérperas mais ricas, aumentando assim as disparidades na oferta da assistência pré-natal

Detection of the human 70-kD and 60-kD heat shock proteins in the vagina: relation to microbial flora, vaginal pH, and method of contraception.

The expression of the 60-kD and 70-kD heat shock proteins (hsp60 and hsp70) in the vaginas of 43 asymptomatic women of reproductive age with or without a history of recurrent vulvovaginitis (RVV) were compared. Vaginal wash samples were obtained and assayed by enzyme-linked immunosorbent assay (ELISA) for human hsp60 and hsp70. Heat shock protein 70 was not detected in any of the 19 women with no history of RVV, and hsp60 was present in only one woman in this group. In contrast, in the RVV group, 11 (45.8%) were hsp60-positive and eight (33.3%) were hsp70-positive. The presence of either heat shock protein in the vagina was associated with an elevated vaginal pH (>4.5). Bacterial vaginosis or Candida was identified in some of the asymptomatic subjects; their occurrence was significantly higher in women with vaginal hsp70 than in women with no heat shock proteins. Oral contraceptives were used by 35.7% of subjects who were negative for vaginal heat shock proteins, as opposed to only 12.5% of women who were positive for hsp70 and 8.3% who were positive for hsp60. Expression of heat shock proteins in the vagina may indicate an altered vaginal environment and a susceptibility to vulvovaginal symptoms

Functional Bosonization of Non-Relativistic Fermions in (2+1)(2+1) Dimensions

We analyze the universality of the bosonization rules in non-relativistic fermionic systems in $(2+1)d$. We show that, in the case of linear fermionic dispersion relations, a general fermionic theory can be mapped into a gauge theory in such a way that the fermionic density maps into a magnetic flux and the fermionic current maps into a transverse electric field. These are universal rules in the sense that they remain valid whatever the interaction considered. We also show that these rules are universal in the case of non-linear dispersion relations provided we consider only density-density interactions. We apply the functional bosonization formalism to a non-relativistic and non-local massive Thirring-like model and evaluate the spectrum of collective excitations in several limits. In the large mass limit, we are able to exactly calculate this spectrum for arbitrary density-density and current-current interactions. We also analyze the massless case and show that it has no collective excitations for any density-density potential in the Gaussian approximation. Moreover, the presence of current interactions may induce a gapless mode with a linear dispersion relation.Comment: 26 Pages, LaTeX, Final version to appear in International Journal of Modern Physics