3,140 research outputs found

    p-Branes from Generalized Yang-Mills Theory

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    We consider the reduced, quenched version of a generalized Yang-Mills action in 4k-dimensional spacetime. This is a new kind of matrix theory which is mapped through the Weyl-Wigner-Moyal correspondence into a field theory over a non-commutative phase space. We show that the ``classical'' limit of this field theory is encoded into the effective action of an open, (4k-1)-dimensional, bulk brane enclosed by a dynamical, Chern-Simons type, (4k-2)-dimensional, boundary brane. The bulk action is a pure volume term, while the boundary action carries all the dynamical degrees of freedom.Comment: 8 pages, LaTeX 2e, no figure

    Responsabilidade social da empresa - motor de eficiência empresarial e desenvolvimento local – o caso Banco Alimentar Contra a Fome Península Setúbal

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    Nesta comunicação serão comentadas as vantagens de inserir na estratégia da empresa práticas de responsabilidade social motoras da eficiência empresarial, as quais serão também importantes como elementos dinamizadores do desenvolvimento da comunidade local. Neste sentido será utilizado a metodologia estudo de caso – aplicada ao Banco Alimentar Contra a Fome Península de Setúbal. Esta instituição congrega esforços quer empresariais quer de organizações locais de apoio ao cidadão e trabalho voluntário. Com esta Organização é dinamizado o “mercado social” complementar ao “mercado de consumo”. O Estado deverá participar neste “sistema solidário” por via da política fiscal.En esta comunicación serán comentadas las ventajas de insertar en la estrategia de la empresa, prácticas de responsabilidad social, motor de la eficiencia de la empresa, que será también un elemento importante para el desarrollo de la comunidad local. La metodología usada será estudio de caso - aplicado al banco alimenticio contra la hambre de la península de Setúbal. Esta institución junta esfuerzos de las empresas, las organizaciones locales para la ayuda al ciudadano y el trabajo voluntario. Esta organización desarrolló el "mercado social" complementar al "mercado de consumo". El Estado tiene un papel importante en este "sistema solidario" por via del diseño de la política de impuesto.In this communication will be commented the advantages to insert in the business strategy, practices of social responsibility, motor of the enterprise efficiency, which will be also an important element for the development of the local community. The methodology used will be case study - applied to the Alimentary Bank Against Hunger Peninsula of Setúbal. This institution congregates efforts from enterprises, local organizations for citizen support and voluntary work. This Organization developed the "social market" complementary to the "market of consumption". The State has an important role in this "solidary system" in what concerns the tax policy design

    Protecting a quantum state from environmental noise by an incompatible finite-time measurement

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    We show that measurements of finite duration performed on an open two-state system can protect the initial state from a phase-noisy environment, provided the measured observable does not commute with the perturbing interaction. When the measured observable commutes with the environmental interaction, the finite-duration measurement accelerates the rate of decoherence induced by the phase noise. For the description of the measurement of an observable that is incompatible with the interaction between system and environment, we have found an approximate analytical expression, valid at zero temperature and weak coupling with the measuring device. We have tested the validity of the analytical predictions against an exact numerical approach, based on the superoperator-splitting method, that confirms the protection of the initial state of the system. When the coupling between the system and the measuring apparatus increases beyond the range of validity of the analytical approximation, the initial state is still protected by the finite-time measurement, according with the exact numerical calculations.Comment: REVISED VERSION: 37 pages, 3 figure

    From the simplest equations of Hydrodynamics to science and engineeringmodeling skills

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    [EN] The development of modeling skills is a very important issue in Science teaching nowadays. The present workillustrates how, from the simplest equations of hydrodynamics, it is possible to contribute to this end. Bernoulliand continuity equations are included in Physics syllabi of secondary and university levels, and can be seen as alinking between general and professional education. By means of the proposed project, students are taken throughgeneral stages which are usually present in any engineering project or research work based on modeling and simu-lation. such as the formulation of the problem, the statement of the Physics model, a computational simulationand the comparison between theory and experiments. This kind of project allows for the development of modelingskills and also to some other typical skills of the scientist's and engineer's pro les nowadays, such as tting andgraphing analysis. It is common to see that secondary and rst year university courses do not contribute muchto the formation of modeling skills, instead they rather contribute to particular skills from the perspective of thedi erent subjects. On the other hand, students are usually more motivated for the modeling of real world situationsthan for idealized ones.[ES] El desarrollo de habilidades relacionadas con la modelación es un aspecto esencial en la enseñanza de las ciencias hoy en día. El presente trabajo ilustra una propuesta de cómo desarrollar habilidades de modelación físico-matemáticas desde las ecuaciones más simples de la hidrodinámica, es decir, la ecuación de Bernoulli y la ecuación de continuidad. Estas ecuaciones representan la conservación de la energía y de la masa, respectivamente, y están presentes comúnmente en los programas de Física para la Enseñanza Secundaria y Universidad. A través del proyecto propuesto, el estudiante transita a través de etapas generales usualmente presentes en los proyectos de innovación ingenieril o de investigación, es decir, el surgimiento de la idea inicial, el planteamiento del modelo físico, la exploración computacional del mismo, y la comparación con medidas experimentales. El proyecto presentado hace uso directo de habilidades tales como la realización de ajustes y análisis gráficos, típicas en los perfiles de ingenieros e investigadores en la actualidad. Por otro lado, los estudiantes presentan más motivación por aquellas situaciones más cercanas a la realidad que por las muy idealizadas.This work has been partially supported by funds of the Interdisciplinar Modeling Group InterTech from the Universitat Politècnica de València, Spain.Castro-Palacio, JC.; Velázquez-Abad, L.; Perea, MH.; Navarro-Pardo, E.; Acosta-Iglesias, D.; Fernández-De-Córdoba-Castellá, P. (2017). Desarrollo de habilidades de modelación desde las ecuaciones más simples de la Hidrodinámica. Modelling in Science Education and Learning. 10(2):211-222. doi:10.4995/msel.2017.7143SWORD211222102Mendonça, P. C. C., & Justi, R. (2013). The Relationships Between Modelling and Argumentation from the Perspective of the Model of Modelling Diagram. International Journal of Science Education, 35(14), 2407-2434. doi:10.1080/09500693.2013.811615Chapman S.J. (2003). Fortran 90/95 for Scientists and Engineers, 2nd Ed. McGraw-Hill Series in General Engineering.Fishbane P.M., Gasiorowicz, S. & Thornton S. (1996). Physics for scientists and engineers. Prentice Hall.Justi, R. S., & Gilbert, J. K. (2002). Science teachers’ knowledge about and attitudes towards the use of models and modelling in learning science. International Journal of Science Education, 24(12), 1273-1292. doi:10.1080/09500690210163198Nair, C. S., Patil, A., & Mertova, P. (2009). Re-engineering graduate skills – a case study. European Journal of Engineering Education, 34(2), 131-139. doi:10.1080/03043790902829281Patil A.S. (2005). The global engineering criteria for the development of a global engineering profession. World Transaction on Engineering Education 4(1), 49-52.Radcliffe D.F. (2005). Innovation as a meta attribute for graduate engineers. International Journal of Engineering Education 21(2), 194-199.Resnick R., Halliday D., & Krane K. (1999). Physics. 4th Ed. Mexico: CECSA.Wedelin, D., Adawi, T., Jahan, T., & Andersson, S. (2015). Investigating and developing engineering students’ mathematical modelling and problem-solving skills. European Journal of Engineering Education, 40(5), 557-572. doi:10.1080/03043797.2014.987648Wellington P., Thomas I., Powell I., & Clarke B. (2002). Authentic assessment applied to engineering and business undergraduate consulting teams. International Journal of Engineering Education 18(2), 168-179

    Total Plasma Homocysteine and Depressive Symptoms in Older Hispanics

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    Background: Very few studies have investigated the association between total plasma homocysteine (tHcy) and depressive symptoms in older Hispanics. Objective: To test the hypothesis that high tHcy associates with depressive symptoms in older Hispanics. Methods: A total of 1,418 participants .55 years old from the Maracaibo Aging Study (MAS) underwent standardized neurological, neuropsychiatric, and cardiovascular assessments. The Neuropsychiatric Inventory Depression Subscale (NPId) was used to assess the burden of depressive symptoms. The tHcy levels and other biochemical parameters in blood samples were measured. Univariate and multivariate logistic regression models were applied. Results: Participants with depressive symptoms had higher levels of tHcy than those without (15.1 versus 13.9 µmol/L; p = 0.009). Elevated tHcy levels were associated with depressive symptoms after adjusting for age, sex, education, smoking, diabetes, hypertension, alcohol intake, stroke, and dementia (OR = 1.58; 95% CI, 1.18-2.12). Conclusion: Elevated levels of tHcy were associated with depressive symptoms in older Hispanics living under the nutritional and environmental conditions of a developing country

    How much time does a measurement take?

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    We consider the problem of measurement using the Lindblad equation, which allows the introduction of time in the interaction between the measured system and the measurement apparatus. We use analytic results, valid for weak system-environment coupling, obtained for a two-level system in contact with a measurer (Markovian interaction) and a thermal bath (non-Markovian interaction), where the measured observable may or may not commute with the system-environment interaction. Analysing the behavior of the coherence, which tends to a value asymptotically close to zero, we obtain an expression for the time of measurement which depends only on the system-measurer coupling, and which does not depend on whether the observable commutes with the system-bath interaction. The behavior of the coherences in the case of strong system-environment coupling, found numerically, indicates that an increase in this coupling decreases the measurement time, thus allowing our expression to be considered the upper limit for the duration of the process.Comment: REVISED VERSION: 17 pages, 2 figure

    Estudo clínico duplo cego comparando praziquantel com oxamniquine

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    Com objetivo de se compararem a tolerabilidade e eficácia do praziquantel e oxamniquine, procedeu-se a um estudo prospectivo duplo-cego envolvendo 120 pacientes com esquistossomose intestinal ou hepatintestinal. Os pacientes foram randomizados em dois grupos. Um foi tratado com praziquantel, na dose de 55 mg/kg de peso, o outro com oxamniquine, 15 mg/kg de peso, sempre administrados em dose única por via oral. O diagnóstico e seguimento parasitológicos basearam-se ho exame de fazes peio método de Kate Katz. Em 73 de 77 casos negativos após tratamento, executaram-se biópsias retais. Efeitos colaterais, principalmente tontura, sonolência, dores abdominais, cefaléia, náuseas e diarréia foram observados em 87% dos casos. Sua incidência, intensidade e duração foram semelhantes em ambos os grupos, mas a dor abdominal foi significativamente mais freqüente após praziquantel, havendo maior tendência para tontura intensa após oxamniquine. Observou-se aumento significante de alamina-aminotransferase e gama-glutamiltransferase após oxamniquine e de bilirrubina total após praziquantel. Um total de 48 pacientes tratados com praziquantel e 46 com oxamniquine completaram os exames de controle até o sexto mês. As percentages de cura foram de 79,2% e de 84,8% respectivamente, diferença não significativa. Os pacientes não curados mostraram redução média do número de ovos de 93,5% e de 84,1%, diferença não significativa. Cinco pacientes retratados com praziquantel curaram-se, mas somente um de três retratados com oxamniquine. Estes resultados mostram, que ambas as drogas-apesar de diferentes propriedades farmacológicas provocam reações colaterais semelhantes e apresentam eficácia terapêutica comparável.A double-blind clinical trial involving 120 patients with chronic schistosomiasis was carried out to compare the tolerability and efficacy of praziquantel and oxamniquine. The patients were randomly allocated into two groups. One was treated with praziquantel, 55 mg/kg of body weight CBWT), and the other one with oxamniquine, 15mg/kg bwt, administered in a single oral dose. The diagnosis and the parasitological follow-up was based on stool examinations by quantitative Kato-Katz method and on rectal biopsies. Side-effects mainly dizziness, sleepness, abdominal distress, headache, nausea and diarrhea were observed in 87% of the cases. Their incidence, intensity and duration were similar for both drugs but abdominal pain was significantly more frequent after praziquantel intake and severe dizziness was more commonly reported after oxamniquine. A significant increase of alanine-aminotransferase and y-glutamyltransferase was found with the latter drug and of total bilirubin with the former one. A total of 48 patients treated with praziquantel and 46 with oxamniquine completed with negative findings the required three post-treatment parasitological controls three slides of each stool sample on the first, third and sixth month. The achieved cure rates were 79.2% and 84.8%, respectively, a difference without statistical significance. The non-cured cases showed a mean reduction in the number of eggs per gram of feces of 93.5% after praziquantel and of 84.1% after oxamniquine. This diference also was not significant. Five patients retreated with praziquantel were cured but only one out of three treated a second time with oxamniquine. These findings show that both drugs despite their different chemical structures, pharmacological properties and mechanisms-of-action induce similar side-effects as well as a comparable therapeutical efficacy, in agreement with the results reported from analogous investigations

    Relaxations in Ba2BiSbO6 Double Complex Perovskite Ceramics

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    The electric properties of the complex double perovskite Ba2BiSbO6 have been investigated using impedance spectroscopy in the frequency range from 1 Hz up to 1 MHz and in the temperature range from room temperature up to 560 K. There are two contributions to the electrical properties due to the grain and grain boundary. The oxygen vacancies play an important role in the conductivity and strongly increase the dielectric constant at high temperatures. The analysis of the frequency dependence of the conductivity clearly shows the structural phase transition of this compound near 515 K
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