126 research outputs found

    Relativistically extended Blanchard recurrence relation for hydrogenic matrix elements

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    General recurrence relations for arbitrary non-diagonal, radial hydrogenic matrix elements are derived in Dirac relativistic quantum mechanics. Our approach is based on a generalization of the second hypervirial method previously employed in the non-relativistic Schr\"odinger case. A relativistic version of the Pasternack-Sternheimer relation is thence obtained in the diagonal (i.e. total angular momentum and parity the same) case, from such relation an expression for the relativistic virial theorem is deduced. To contribute to the utility of the relations, explicit expressions for the radial matrix elements of functions of the form rλr^\lambda and βrλ\beta r^\lambda ---where β\beta is a Dirac matrix--- are presented.Comment: 21 pages, to be published in J. Phys. B: At. Mol. Opt. Phys. in Apri

    Dimensionalities of Weak Solutions in Hydrogenic Systems

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    A close inspection on the 3D hydrogen atom Hamiltonian revealed formal eigenvectors often discarded in the literature. Although not in its domain, such eigenvectors belong to the Hilbert space, and so their time evolution is well defined. They are then related to the 1D and 2D hydrogen atoms and it is numerically found that they have continuous components, so that ionization can take place

    Co‐occurrence and clustering of sedentary behaviors, diet, sugar‐sweetened beverages, and alcohol intake among adolescents and adults: The latin american nutrition and health study (elans)

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    Poor diet, sedentary behaviors, sugar‐sweetened beverages (SSB) and alcohol intake seem to co‐exist in complex ways that are not well understood. The aim of this study was to provide an understanding of the extent to which unhealthy behaviors cluster in eight Latin America countries. A secondary aim was to identify socio‐demographic characteristics associated with these behaviors by country. Data from adolescents and adults from the “Latin American Health and Nutrition Study” was used and the prevalence of screen‐time, occupational and transportation–sedentary time, socializing with friends, poor diet, SSB and alcohol intake, alone and in combination, were identified. The eight Latin America (LA) countries added to analyses were: Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Peru, and Venezuela. Logistic regression was used to estimate associations between ≥2 behaviors clustering, socio‐demographics and weight status. Among 9218 individuals, the most prevalent behaviors were transportation and occupation–sedentary time, SSB and alcohol intake. Younger, female, married/living with a partner, low and middle‐income and obese individuals had higher chances for these clustering behaviors. These results provide a multi-country level of understanding of the extent to which behaviors co‐occur in the LA population.University of San FranciscoRevisión por pare

    Costos y viabilidad económica de la producción y comercialización de la conserva de trucha (Oncorhynchus mykiss) en escabeche

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    Puno is the first rainbow trout producing region in Peru. The objective of the study was to study the feasibility of giving added value to trout. The cost analysis and financial viability of the production of six types of canned pickled trout preserves were considered. The fillets were obtained from trout fed with three commercial foods (Salmofood®, Naltech® and Tomasino®) and the preserves had two presentations (can vs. glass). The production costs were calculated through a documented record of data at market prices. The general theory of production costs was applied and through the cash flow financial tool the profitability indicators were found. The financial net present value (NPVf) was positive for all six presentations. The internal rate of return (IRR), both for canning (34.5, 37.5 and 42.8%) and for glass canning (34.7, 38.2 and 44.3%) was higher than the opportunity cost of capital (COK) and in both cases, the benefit-cost ratio (B/C) was similar and greater than one (1.05, 1.06 and 1.07) for the three commercial foods, respectively. The capital recovery period was between 5 and 6 years for the two types of preserves. In conclusion, the pickled trout canning project is profitable and, therefore, its investment is recommended to contribute to the sustainability of production and improve the income of producers in the region.Puno es la primera región productora de truchas arcoíris en el Perú. El estudio tuvo como objetivo estudiar la factibilidad de dar valor agregado a la trucha. Se consideró el análisis de costos y la viabilidad financiera de la producción de seis tipos de conservas de trucha en escabeche. Los filetes fueron obtenidos de truchas alimentadas con tres alimentos comerciales (Salmofood®, Naltech® y Tomasino®) y las conservas tuvieron dos presentaciones (lata vs. vidrio). Los costos de producción se calcularon mediante un registro documentado de datos a precios de mercado. Se aplicó la teoría general de costos de producción y mediante la herramienta financiera de flujo de caja se hallaron los indicadores de rentabilidad. El valor actual neto financiero (VANf) fue positivo para las seis presentaciones. La tasa interna de retorno (TIR), tanto para la conserva de lata (34.5, 37.5 y 42.8%) como para la conserva en vidrio (34.7, 38.2 y 44.3%) fue mayor al costo de oportunidad del capital (COK) y en ambos casos la ratio beneficio-costo (B/C) fue similar y mayor a uno (1.05, 1.06 y 1.07) para los tres alimentos comerciales, respectivamente. El periodo de recuperación del capital estuvo entre 5 y 6 años para los dos tipos de conservas. En conclusión, el proyecto de elaboración de conservas de trucha en escabeche es rentable y, por tanto, es recomendable su inversión para contribuir con la sostenibilidad de la producción y mejorar los ingresos de los productores de la región

    Movimientos indígenas y respuestas estatales frente a la pandemia en México, Ecuador y Brasil

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    La pandemia de la covid-19 puso de manifiesto el rol del Estado y de los Gobiernos en la gestión de esta situación de emergencia, así como la capacidad de los movimientos sociales para proponer formas de acción colectiva, de autonomía y de solidaridad. Con base en la observación de medios digitales pertenecientes a movimientos indígenas en México, Ecuador y Brasil –entre marzo de 2020 y julio de 2021– se analiza cómo estos movimientos han reorganizado sus formas de resistencia y han llevado a cabo acciones basadas en sus demandas, al visibilizar la ausencia y negligencia del Estado y establecer alianzas o asumir el reto de manera autónoma. Los casos abordados en el presente artículo permiten ampliar la comprensión sobre la potencia e importancia del accionar de los movimientos sociales, y, a la vez, proponer un entendimiento de la pandemia que atraviesa múltiples dimensiones sociales y ambientales, más allá de la cuestión sanitaria.

    Relativistic Kramers-Pasternack Recurrence Relations

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    Recently we have evaluated the matrix elements ,where where O ={1,\beta, i\mathbf{\alpha n}\beta} arethestandardDiracmatrixoperatorsandtheangularbracketsdenotethequantummechanicalaveragefortherelativisticCoulombproblem,intermsofgeneralizedhypergeometricfunctions are the standard Dirac matrix operators and the angular brackets denote the quantum-mechanical average for the relativistic Coulomb problem, in terms of generalized hypergeometric functions _{3}F_{2}(1) $ for all suitable powers and established two sets of Pasternack-type matrix identities for these integrals. The corresponding Kramers--Pasternack three-term vector recurrence relations are derived here.Comment: 12 pages, no figures Will appear as it is in Journal of Physics B: Atomic, Molecular and Optical Physics, Special Issue on Hight Presicion Atomic Physic

    Pashto Border Literature as Geopolitical Knowledge

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    In this article I read a selection of Pashto literatures as critical thought about geopolitics. Drawing on Michael Shapiro’s concept of aesthetic subjects, as well as on border theory, I argue that the authors, the content, and the literary networks of these works all comment on global relations of power, ranging from the local bordering effects of geopolitics, to systems of knowledge embedded in the spatiality and temporality of empire. I argue that past and current imperial processes have led to fragmenting effects in Afghan society, and literature both reflects and analyzes this. Beyond that, I argue—through the examples of authors’ lives as well as their work—that literary activity in Pashto has actively negotiated such processes throughout its history, and offers strategies for countervailing notions of global connectivity in action as well as thought. The decentralized and multiperspective images of life in these works sit in counterpoint not only to the systems-oriented views that drive military and other policy in Afghanistan during the ongoing US moment, but also to universalist perspectives upon which disciplines like world history and geopolitics traditionally rely. Additionally, though, Pashto literary networks themselves also produce alternative structures. This contributes to the aesthetic turn in IR by arguing that it is not only the aesthetic vision in works that challenges dominant knowledge; the shape of the Pashto literary formation itself, organic with its content, is an alternate form of knowledge-in-practice about the contemporary world

    Perceived urban environment attributes and obesity indices in adults: an 8-nation study from Latin America

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    © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.This study examines the associations between perceived urban environment attributes and obesity indices by country using data from an eight-nation study from Latin America. The data were collected from 8185 adults. The Neighbourhood Environment Walkability-abbreviated scale was used to assess perceived urban environment attributes. Obesity indices considered were body mass index, waist circumference, neck circumference, a body shape index and waist-to-height ratio. The perception of a more and better land use mix-diversity (β - 0.44; 95% CI - 0.59, - 0.28), traffic safety (- 0.39; - 0.66, - 0.12), and safety from crime (- 0.36; - 0.57, - 0.15) was associated with lower body mass index across the entire sample. Land use mix-diversity (- 1.21; - 1.60, - 0.82), street connectivity (- 0.26; - 0.37, - 0.15), and traffic safety (- 0.79; - 1.47, - 0.12) were negatively associated with waist circumference. Land use mix-diversity (- 0.11; - 0.20, - 0.03), land use mix-access (- 0.23; - 0.34, 0.12), walking/cycling facilities (- 0.22; - 0.37, - 0.08), and safety from crime (- 0.27; - 0.42, - 0.12) were negatively associated with neck circumference. No associations between perceived urban environment attributes and a body shape index were found. Land use mix-diversity (- 0.01; - 0.02, - 0.01), aesthetics (- 0.02; - 0.03, - 0.01), and safety from crime (- 0.02; - 0.04, - 0.01) were associated with waist-to-height ratio. Environmental interventions involving urban environment attributes are associated with obesity indices and, therefore, may help decrease the prevalence of overweight and obesity.info:eu-repo/semantics/publishedVersio

    Association between Active Transportation and Public Transport with an Objectively Measured Meeting of Moderate-To-Vigorous Physical Activity and Daily Steps Guidelines in Adults by Sex from Eight Latin American Countries

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    This study aimed to examine the associations between active transportation and public transport and the objectively measured meeting of moderate-to-vigorous physical activity (MVPA) and steps per day guidelines in adults by sex from eight Latin American countries. As part of the Latin American Study of Nutrition and Health (ELANS), data were collected from 2524 participants aged 18–65 years. MVPA and steps per day were evaluated using Actigraph GT3X accelerometers. The mode of transportation, its frequency and duration were collected using a self-reported questionnaire. The average time dedicated to active transportation was 12.8 min/day in men (IQR: 2.8–30.0) and 12.9 min/day in women (IQR: 4.3–25.7). A logistic regression analysis was conducted, showing that active transportation (≥10 min) was associated with higher odds of meeting MVPA guidelines (men: OR: 2.01; 95%CI: 1.58–2.54; women: OR: 1.57; 95%CI: 1.25–1.96). These results show a greater association when considering active transportation plus public transport (men: OR: 2.98; 95%CI: 2.31–3.91; women: OR: 1.82; 95%CI: 1.45–2.29). Active transportation plus public transport was positively associated with meeting steps per day guidelines only in men (OR: 1.55; 95%CI: 1.15–2.10). This study supports the suggestion that active transportation plus public transport is significantly associated with meeting the MVPA and daily steps recommendations.Fieldwork and data analysis formulated in the ELANS protocol was supported by a scientific grant from the Coca Cola Company (2014/24168-6), and by grant and/or support from Instituto Pensi/Hospital Infantil Sabara, International Life Science Institute of Argentina, Universidad de Costa Rica, Pontificia Universidad Católica de Chile, Pontificia Universidad Javeriana, Universidad Central de Venezuela (CENDES-UCV)/Fundación Bengoa, Universidad San Francisco de Quito, and Instituto de Investigación Nutricional de Peru. The funding sponsors had no role in study design; the collection, analyses, or interpretation of data; writing of the manuscript; or in the decision to publish the results
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