Implications for the design of experimental and observational studies

AXA Research Fun

The presence of White students and the emergence of Black-White within-school inequalities: two interaction-based mechanisms

This article investigates mechanism-based explanations for a well-known empirical pattern in sociology of education, namely, that Black-White unequal access to school resources -- defined as advanced coursework -- is the highest in racially diverse and majority-White schools. Through an empirically calibrated and validated agent-based model, this study explores the dynamics of two qualitatively informed mechanisms, showing (1) that we have reason to believe that the presence of White students in school can influence the emergence of Black-White advanced enrollment disparities and (2) that such influence can represent another possible explanation for the macro-level pattern of interest. Results contribute to current scholarly accounts of within-school inequalities, shedding light into policy strategies to improve the educational experiences of Black students in racially integrated settings

A construçao das redes sociais de operadores e ONG’s : os mecanismos de recrutamento a partir das relés sociais

Pretendemos, neste artigo, investigar os processos subjacentes às trajetórias os operadores de ONGs: como são recrutados, quais seus campos de filiação institucional mais freqüentes, que características mais significativas podem ser destacadas neste processo. Trata-se, de um lado, de desvelar o mecanismo de formação das redes sociais destes atores; de outro, investigar as suas diversas inserções em campos de sociabilidade. A partir de um estudo empírico de operadores de Organizações Não Governamentais que atuam na área de Educação na Região Metropolitana do Recife procedemos à reconstrução de suas trajetórias de sociabilidade.The following article investigates certain processes that undergo the professional trajectory of NGOs officials: how they are recruited, what are their most common institutional fields of affiliation, what significant features could be identified in these processes. Our aim here is twofold: on the one hand, to reveal the mechanisms which account for the formation of these actors social networks. On the other hand, we investigate their different insertions in fields of sociability. The concept of social relais – here understood as a mechanism that produces and disseminates the mobilization of individuals from constituted to new networks, creating networks of networks – is used in the analysis of information about NGOs officials working in the field of education in the Metropolitan Region of Recife

Method for semi-automated image segmentation of blood vessels in MRI images

INTRODUCTION Atherosclerosis is considered the main pathological process responsible for ischemic stroke [1]. It consists in the accumulation of fatty materials (plaque) in the wall of blood vessels. This phenomenon leads the vessel to thicken, which, consequently, results in less expansion of the vessel within a cardiac cycle. Also, the vessel tends to expand unevenly in the different directions. Medical imaging techniques such as Magnetic Resonance Imaging have been greatly used for diagnosis of atherosclerosis through visual evaluation of the images. However, due to the qualitative nature of these procedures, one can lead to ambiguous results depending on the quality of the obtained images and on the accuracy of the operator. Also, this procedure is very time-consuming, taking about 7-9 minutes per sequence of 16 phases. This project proposes a method for segmentation of vessels in MRI images with the use of image processing techniques coded in MATLAB, in order to solve time and accuracy issues. METHODS The developed program consists in five main parts: Data Input, User Input, Analysis and Correction, Radial Segmentation and Data Output. Data Input gathers all the necessary data such as the MRI scans and its parameters. The images are resized and have the contrast increased., User Input prompts the user to click in specific spots on the desired vessel, which is being shown as a figure. They are used as references for setting threshold values in respect to each direction from the center of the vessel. Then, the program runs by itself in Analysis and Correction by evaluating intensity values as a function of the angle from the center of the vessel (where zero degrees is east), interpolating it and then calculating intensity threshold as a function of the angle. In Radial Segmentation, sets of vectors are grown radially from the center of the vessel. They will stop growing once the threshold value in the current direction is reached in its extremity. Each vector length is recorded in an array that is used to calculate an average area of the vessel for each phase. Finally, in Data Output, the boundaries of the vessel are shown in a set of images (Figure 1), and the area values and dilation percentage are printed on the screen.   Figure 1. Final plots. Each frame corresponds to one cardiac phase. The segmented boundaries are shown as green lines. RESULTS AND CONCLUSIONS Manual measurements made by 3 individuals on 1400 images of 10 volunteers, have been compared to the same measurements made by the program. It has been obtained a p-value of approximately 0.94, consequently showing that there is no significant statistical difference between manual and the semi-automated measurements. The time consumed in the process was reduced by a factor of 24, from about 8m per about 20s per sequence of 16 phase slides. Furthermore, one can use the sharp and accurate segmented borders of the vessel in order to qualitatively analyse the patient’s vessel

Networks, sociabilities and health: the role of mental health support in Brazil

The occidental model of mental health support, dominant in Brazil, cannot be understood without considering nonprofessional curative practices and social representations of health and sickness. Here I summarize my research of the past several years on mental health and sociabilities, based on observation in institutions for mental health support in Brazilian cities

Adjusting for academic preparedness when estimating enrollment disparities in advanced high school coursework

Whether racial disparities in enrollment in advanced high school coursework can be attributed to differences in prior academic preparation is a central empirical question in sociological research, with important implications for education policy. However, the regression-based approaches to this question that are predominant in the literature suffer significant methodological limitations by implicitly assuming that students are similarly prepared if and only if they have similar values on a selected set of academic background measures. Here, we provide a general technique to estimate enrollment disparities in advanced coursework between similarly-prepared students of different races that is less vulnerable to these limitations. We introduce a novel measure of academic preparedness, a student's ex-ante probability of "success" in the course, directly adjust for this single measure in a regression model of enrollment on race, and assess the robustness of estimated disparities to potential unmeasured confounding. We illustrate this approach by analyzing Black-White disparities in AP mathematics enrollment in a large, urban, public school system in the United States. We find that preexisting differences in academic preparation do not fully explain the under-representation of Black students relative to White students in AP mathematics, and contrast our results with those from traditional approaches

Enquadramentos da confissão da homossexualidade masculina durante a epidemia de aids no Brasil (1985-1995)

This article analyzes the speeches of confession of male homosexuality at the time of the appearance of aids in Brazil. With an epidemic crisis and a choice of homosexuals as one of the groups accused of spreading a disease, there was a great effort in the media and Brazilian cinema to stimulate HIV-positive homosexuals to publicly assume themselves. In this sense, the homosexual press of the 1980s minimized the speeches of confession of homosexuality. The gay press of the 1990s, in turn, resisted the stigmatizing discourse, decided to publicly declare themselves homosexual despite the aid. Gathering a set of sources, showing ways and meanings to publicly frame homosexual cis men during the aids context.Neste artigo analiso os discursos de confissão da homossexualidade masculina na época do surgimento da aids no Brasil. Com a emergência da epidemia e da eleição dos homossexuais como um dos grupos acusados de disseminar a doença, houve um esforço da grande mídia e do cinema brasileiro em incentivar que homossexuais soropositivos se assumissem publicamente. Nesse sentido, a imprensa homossexual dos anos 1980 minimizou discursos de confissão das homossexualidades. A imprensa gay dos anos 1990, por sua vez, resistindo ao discurso estigmatizante e apesar da aids, resolveu se afirmar publicamente homossexual. Reunindo um conjunto de fontes, apresento maneiras e sentidos de enquadrar publicamente homens homossexuais cis durante o contexto da aids

Política social: desafíos históricos y contemporáneos en América Latina

El trabajo presenta las reflexiones acerca de la trayectoria de las políticas sociales en América Latina, destacándose el carácter contradictorio de su desarrollo y los desafíos pendientes por lograr en términos de la ampliación de los derechos sociales y ciudadanía, agravados por el contexto de político actual

Regulação hormonal na ingestão alimentar: um breve relato

The purpose of a literature review was to explain about the hormonal regulation and neural control of thefood intake and body weight. The ingestion of macronutrients, the energy cost of food and hormonesynthesis that increases the activity of the orexygenic and anorexygenic neurons are determinative factors in the regulation of the food intake and body weight. The leptin, insulin and peptide YY increaseactivity of the anorexygenic neurons POMC/CART. However, the ghrelin increases activity of the orexygenicneurons NPY/AgRP. These hormones crossing the barrier hematoencephalic and binds to specificsreceptors in the hypothalamic arcuate nucleus. These mechanisms show to the complexity of the foodintake control and all the involved centers in the search for the energy homeostasis.O objetivo deste trabalho de revisão foi dissertar sobre a regulação hormonal da ingestão alimentar e dopeso corporal. A ingestão de macronutrientes, o gasto energético e o balanço entre a síntese de hormô-nios que aumentam a atividade dos neurônios orexígenos e anorexígenos são fatores determinantesna regulação da ingestão alimentar e no controle do peso corporal. Os hormônios leptina, insulina e opeptídeo YY são grandes potenciadores da atividade dos neurônios anorexígenos POMC/CART. Poroutro lado, a ação da grelina aumenta a atividade dos neurônios orexígenos NPY/AgRP. Estes hormônios sintetizados perifericamente atravessam a barreira-hemato-encefálica e se ligam aos seus receptores no núcleo arqueado hipotalâmico com o objetivo de regular a ingestão alimentar e controlar obalanço energético. Estes mecanismos revelam a complexidade do controle do balanço energético etodos os centros envolvidos na busca pela homeostase energétic

Cuidado intergeneracional como estrategia de sobrevivencia en contextos de desigualdad social

This work aims to debate the centrality of intergenerational care, represented by female care networks, in which grandmothers have a primary role, to ensure social reproduction in the current Brazilian context. The limits of the living and working conditions faced by poor urban families make it very difficult for them to cope with job insecurity, unemployment, low wages, together with the absence or precariousness of services and benefits aimed at supporting families in guaranteeing the care necessary for the well-being of their members. It is important to analyze the importance of these intergenerational networks in the context of social protection, highlighting their contradictions in terms of gender, class, race and ethnic relations.Este trabajo busca debatir la centralidad del cuidado intergeneracional, representado por las redes femeninas de cuidado, en las cuales las abuelas tienen un rol primordial, para garantizar la reproducción social en el contexto brasileño actual. Los límites de las condiciones de vida y de trabajo que enfrentan las familias urbanas pobres les impone grandes dificultades para hacer frente a la inseguridad laboral, el desempleo, los bajos salarios, unido a la ausencia o precariedad de servicios y beneficios dirigidos al apoyo a las familias en lo que se refiere a garantizar cuidados necesarios para el bienestar de sus miembros. Es importante analizar la importancia de estas redes intergeneracionales en el contexto de la protección social, destacando sus contradicciones en lo que se refiere a relaciones de género, clase, raza y etnia