3,312 research outputs found
p-Branes from Generalized Yang-Mills Theory
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
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
Recommended from our members
Effectiveness of Insecticide Spraying and Culling of Dogs on the Incidence of Leishmania infantum Infection in Humans: A Cluster Randomized Trial in Teresina, Brazil
Background: To evaluate the effect of insecticide spraying for vector control and elimination of infected dogs on the incidence of human infection with L. infantum, a randomized community intervention trial was carried out in the city of Teresina, Brazil. Methods/Principal Findings Within each of ten localities in the city, four blocks were selected and randomized to 4 interventions: 1) spraying houses and animal pens with insecticide; 2) eliminating infected dogs; 3) combination of spraying and eliminating dogs, and 4) nothing. The main outcome is the incidence of infection assessed by the conversion of the Montenegro skin test (MST) after 18 months of follow-up in residents aged ≥1 year with no previous history of visceral leishmaniasis (VL). Reactions were measured at 48–72 h, induration of ≥5 mm considered positive. Interventions were executed after the baseline interview and repeated 6 and 12 months later. The effects of each type of intervention scheme on the incidence of infection were assessed by calculating relative risks and 95% confidence intervals using Poisson population-averaged regression models with robust variance. Among the 1105 participants, 408 (37%) were MST positive at baseline. Of the 697 negatives, only 423 (61%) were reexamined at the end of the follow-up; 151 (36%) of them converted to a positive MST. Only dog culling had some statistically significant effect on reducing the incidence of infection, with estimates of effectiveness varying between 27% and 52%, depending on the type of analysis performed. Conclusions/Significance: In light of the continuous spread of VL in Brazil despite the large scale deployment of insecticide spraying and dog culling, the relatively low to moderate effectiveness of dog culling and the non-significant effect of insecticide spraying on the incidence of human infection, we conclude that there is an urgent need for revision of the Brazilian VL control program
Protecting a quantum state from environmental noise by an incompatible finite-time measurement
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
[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
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?
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
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
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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