284 research outputs found

    A relativistically covariant stochastic model for systems with a fluctuating number of particles

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    We construct a relativistically covariant stochastic model for systems of non-interacting spinless particles whose number undergoes random fluctuations. The model is compared with the canonical quantization of the free scalar field in the limit of infinite volume.Comment: 5 Pages; no figures; Plain REVTeX style. To be published in Phys. Lett.

    Comfort and energy consumption in a hybrid tunnel-type broiler barn in different bioclimatic zones of Brazil

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    La producción avícola está influenciada directamente por sus condiciones ambientales, y por ende, las condiciones de confort, bienestar animal y consumo energético de las instalaciones. El objetivo de este estudio fue realizar una evaluación de las necesidades de climatización para un galpón de presión negativa en modo túnel (hibrido), en 12 ciudades brasileras ubicadas en las 8 zonas bioclimáticas del país. Se encontró que las ciudades ubicadas en las zonas bioclimáticas 1 y 2 requieren mayor consumo de energía para la calefacción durante la primera fase (0-21 días), mientras que las zonas 7 y 8, requieren más energía para enfriamiento durante la segunda fase (22-42 días). Las ciudades ubicadas en las zonas 3, 4, 5 y 6 presentan las mejores condiciones de confort y el mayor ahorro energético para las dos fases

    Can Education Reduce Political Polarization?: Fostering Open-Minded Political Engagement during the Legislative Semester

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    Background: In the United States, elected leaders and the general public have become more politically polarized during the past several decades, making bipartisan compromise difficult. Political scientists and educational scholars have argued that generating productive political cooperation requires preparing members of democratic societies to productively negotiate their political disagreements. Numerous prior studies on civic learning have focused on fostering youth political engagement, but little research has examined how educators can support both political engagement and political open-mindedness. Purpose: The study described in this paper explores how students’ experiences in a unique high school government course may help to foster their open-minded political engagement (OMPE) which we define as an individual’s propensity to explore and participate in political affairs while maintaining a willingness to adjust one’s political views. Research Design: Using quantitative and qualitative methods, we examined the development of adolescents’ OMPE during their participation in high school government courses at three schools. Whereas participants at Standard High (N=87) completed a traditional government course, students at Green High (N=224) and Gomez High (N=94) were enrolled in the Legislative Semester course, an extended political simulation that required students to research, discuss, debate, and mock-vote on controversial public issues. At each research site, we gathered data through student surveys, teacher and student interviews, and classroom observations during the fall 2014-15 semester. We analyzed survey data using principal component analysis, t-tests, and OLS regression, and we conducted constant comparative analysis with our qualitative data. Findings: Students in the LS program became more politically engaged and open-minded than students in the traditional government course. Whereas studying and exploring various political issues was especially helpful for the development of political engagement, considering diverse political perspectives in an open classroom environment was helpful for the development of political open-mindedness. However, if students in the LS were encouraged to be partisan, they were less likely to develop greater political open-mindedness. Conclusions: Repeated opportunities to examine diverse political ideas with peers can foster the development of open-minded political engagement. Educators can support such exchanges not only through structuring substantive sharing of diverse political perspectives but also through creating emotionally “safe” classroom environments, encouraging the expression of minority viewpoints, and de-emphasizing partisan uniformity. Encouraging careful listening – rather than polite hearing – may be central for the development of political open-mindedness

    Thermal environment in two broiler barns during the first three weeks of age

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    The objective of this research was to evaluate the internal thermal environment of two broiler barns featuring different ventilation systems representative of Brazilian and South American poultry production industry: (a) a negative-pressure tunnel and (b) a positive- pressure lateral ventilation system. Environmental parameters such as dry bulb temperature, relative humidity and temperature-humidity index were assessed; temperature maps for day and night average conditions were determined for the first three weeks of life. Better uniformity of the thermal environment and comfort conditions inside the negative-pressure tunnel were found

    Social capital and factors associated with the caries experience in adults : a population-based study in Brazil

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    The objective of this study was to investigate the experience of caries related to social capital and associated factors in adults in large-scale population-based study. A Cross-sectional study was performed in 163 municipalities in the State of São Paulo, Brazil (SBSP-2015). 17,560 people were evaluated, of which 6051 were adults aged 35-44 years. Hierarchical logistic regression analysis was proposed. Outcome variables (decayed teeth, missing teeth and DMFT) and independent variables were included in the model, considering the distal (income and schooling); intermediate (social capital) and proximal levels (sex and ethnicity). Results showed that income up to 1,500 reais - US$ 367.6 in 11/11/2019 - (OR = 1.91;1.75-2.08), schooling up to 8 years (OR = 1.32;1.12-1.56) and non-white ethnicity (OR = 1.54;1.35-1.76) were more likely to have decayed teeth. Income up to 1500 reais (OR = 1.29;1.15-1.44), schooling up to 8 years (OR = 2.13;1.90-2.38), low social capital (OR = 1.84;1.65-2.04), medium social capital (OR = 1.15;1.01-1.30) and females were more likely to have lost teeth (OR = 1.13;1.03-1.23). Schooling up to 8 years (OR = 1.51;1.35-1.69), low social capital (OR = 1.25; 1.14-1.37) and female (OR = 1.40,1.19-1.53) were associated with DMFT. It was concluded that sociodemographic factors and low social capital were associated with the experience of caries, which should be taken into account in the formulation of public policies3

    Malocclusion and dental appearance in underprivileged brazilian adolescents

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    Satisfaction with dental aesthetics is a subjective indicator used in epidemiological studies and is related to health behaviours. Little is known about the factors that influence this indicator, particularly among adolescents who live in a situation of social vulnerability. The aim of this study was to investigate the relationship between malocclusion and dental appearance in underprivileged Brazilian adolescents. This analytical cross-sectional study was conducted in Piracicaba, Brazil, and evaluated 884 adolescents from 13 to 19 years of age. The dependent variable was satisfaction with dental appearance, and the independent variables were classified as individual (components of the Dental Aesthetic Index - DAI, sex and age) and contextual (social exclusion index). For statistical analysis, multilevel regression models were estimated. The individual variables were considered Level 1, and the contextual variable was considered Level 2, with a level of significance of 5%. The mean age of the adolescents was 15.3 years. Female adolescents more frequently affirmed that they were satisfied with their dental appearance than did male individuals. There was an increase in dissatisfaction with oral health with the increase in anterior maxillary overjet, midline diastema, larger anterior irregularity in the maxilla, larger anterior irregularity in the mandible, anterior open bite and antero-posterior molar relation. Satisfaction with dental appearance was associated with individual factors such as sex and DAI components33CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ141654/2013-

    Anti-Advanced glycation end-product and free radical scavenging activity of plants from the yucatecan flora

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    Background: Formation and accumulation of advanced glycation end-products (AGE) is recognized as a major pathogenic process in diabetic complications, atherosclerosis and cardiovascular diseases. In addition, reactive oxygen species and free radicals have also been reported to participate in AGE formation and in cell damage. Natural products with antioxidant and antiAGE activity have great therapeutic potential in the treatment of diabetes, hypertension and related complications. Objective: to test ethanolic extracts and aqueous-traditional preparations of plants used to treat diabetes, hypertension and obesity in Yucatecan traditional medicine for their anti-AGE and free radical scavenging activities. Materials and Methods: ethanolic extracts of leaves, stems and roots of nine medicinal plants, together with their traditional preparations, were prepared and tested for their anti-AGE and antioxidant activities using the inhibition of advanced glycation end products and DPPH radical scavenging assays, respectively. Results: the root extract of C. fistula (IC50= 0.1 mg/mL) and the leaf extract of P. auritum (IC50= 0.35 mg/mL) presented significant activity against vesperlysine and pentosidine-like AGE. Although none of the aqueous traditional preparations showed significant activity in the anti-AGE assay, both the traditional preparations and the ethanolic extracts of E. tinifolia, M. zapota, O. campechianum and P. auritum showed significant activity in the DPPH reduction assay. <65Conclusions: the results suggest that the metabolites responsible for the detected radical-scavenging activity are different to those involved in inhibiting AGE formation; however, the extracts with antioxidant activity may contain other metabolites which are able to prevent AGE formation through a different mechanism

    The nuclear energy density functional formalism

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    The present document focuses on the theoretical foundations of the nuclear energy density functional (EDF) method. As such, it does not aim at reviewing the status of the field, at covering all possible ramifications of the approach or at presenting recent achievements and applications. The objective is to provide a modern account of the nuclear EDF formalism that is at variance with traditional presentations that rely, at one point or another, on a {\it Hamiltonian-based} picture. The latter is not general enough to encompass what the nuclear EDF method represents as of today. Specifically, the traditional Hamiltonian-based picture does not allow one to grasp the difficulties associated with the fact that currently available parametrizations of the energy kernel E[g,g]E[g',g] at play in the method do not derive from a genuine Hamilton operator, would the latter be effective. The method is formulated from the outset through the most general multi-reference, i.e. beyond mean-field, implementation such that the single-reference, i.e. "mean-field", derives as a particular case. As such, a key point of the presentation provided here is to demonstrate that the multi-reference EDF method can indeed be formulated in a {\it mathematically} meaningful fashion even if E[g,g]E[g',g] does {\it not} derive from a genuine Hamilton operator. In particular, the restoration of symmetries can be entirely formulated without making {\it any} reference to a projected state, i.e. within a genuine EDF framework. However, and as is illustrated in the present document, a mathematically meaningful formulation does not guarantee that the formalism is sound from a {\it physical} standpoint. The price at which the latter can be enforced as well in the future is eventually alluded to.Comment: 64 pages, 8 figures, submitted to Euroschool Lecture Notes in Physics Vol.IV, Christoph Scheidenberger and Marek Pfutzner editor
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