2,860 research outputs found
E_{10} Symmetry in One-dimensional Supergravity
We consider dimensional reduction of the eleven-dimensional supergravity to
less than four dimensions. The three-dimensional nonlinear
sigma model is derived by direct dimensional reduction from eleven dimensions.
In two dimensions we explicitly check that the Matzner-Misner-type
symmetry, together with the , satisfies the generating relations of
under the generalized Geroch compatibility (hypersurface-orthogonality)
condition. We further show that an extra symmetry, which is newly
present upon reduction to one dimension, extends the symmetry algebra to a real
form of . The new acts on certain plane wave solutions
propagating at the speed of light. To show that this cannot be
expressed in terms of the old but truly enlarges the symmetry, we
compactify the final two dimensions on a two-torus and confirm that it changes
the conformal structure of this two-torus.Comment: 33 pages, 3 figures. The action of the Chevalley generators of
SL(2,R)_8 is corrected. Commutativity of SL(2,R)_0 and SL(2,R)_8 is checked
in detail. The generalized Geroch compatibility (hypersurface-orthogonality)
condition is derive
The pleiotropic transcriptional regulator NlpR contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci
The regulatory mechanisms involved in lipogenesis and triacylglycerol (TAG) accumulation are largely unknown in oleaginous rhodococci. In this study a regulatory protein (here called NlpR: Nitrogen lipid Regulator), which contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci was identified. Under nitrogen deprivation conditions, in which TAG accumulation is stimulated, the nlpR gene was significantly upregulated, whereas a significant decrease of its expression and TAG accumulation occurred when cerulenin was added. The nlpR disruption negatively affected the nitrate/nitrite reduction as well as lipid biosynthesis under nitrogen-limiting conditions. In contrast, its overexpression increased TAG production during cultivation of cells in nitrogen-rich media. A putative ‘NlpR-binding motif’ upstream of several genes related to nitrogen and lipid metabolisms was found. The nlpR disruption in RHA1 strain led to a reduced transcription of genes involved in nitrate/nitrite assimilation, as well as in fatty acid and TAG biosynthesis. Purified NlpR was able to bind to narK, nirD, fasI, plsC and atf3 promoter regions. It was suggested that NlpR acts as a pleiotropic transcriptional regulator by activating of nitrate/nitrite assimilation genes and others genes involved in fatty acid and TAG biosynthesis, in response to nitrogen deprivation.Fil: Hernández, Martín Alejandro. Universidad Nacional de la Patagonia "san Juan Bosco". Instituto de Biociencias de la Patagonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biociencias de la Patagonia; ArgentinaFil: Lara, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gago, Gabriela Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gramajo, Hugo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Alvarez, Hector Manuel. Universidad Nacional de la Patagonia "san Juan Bosco". Instituto de Biociencias de la Patagonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biociencias de la Patagonia; Argentin
A Simulation Approach to Solve Power System Transmission Problems
The cost of electricity is an indicator of a country´s level of development. This industry involves billions of dollars. Hence, the operation of Electric Power Systems constitutes a real problem that consists of a set of stages related to distinct components. In this paper, we propose a novel simulation model to study the state of transmission line systems due to scheduled and unscheduled maintenances. The simulation model is founded in an extension of the Discrete Event System Specification formalism called Routed DEVS. The transmission line system is modeled with a set of discrete-event simulation models that provide a complete state description of components. Such a simulation model can be adapted to describe any transmission line system through a network topology. A case study is presented with aims to show who the simulation works. Our proposal is the starting point to study real-life operations of Electric Power Systems from generation to transmission stages.Fil: Blas, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; ArgentinaFil: Alvarez, Gonzalo Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentin
Evaluating New Voting Technologies in Latin America
Having remained virtually unchanged since the enactment of universal and secret suffrage at the end of the nineteenth century, voting procedures are undergoing a radical transformation in many countries through the introduction of electronic methods of voting. Almost 30 countries around the world are currently in process of testing or implementing electronic voting, and in at least 10 countries e-voting is the main method used to elect national representatives (Alvarez and Hall 2008; Pomares 2009). Although it might be assumed that electronic voting would be more likely to arise in established democracies, e-voting has disseminated rapidly and extensively in the developing world. Two of the most populous democracies in the world, Brazil and India, are among the pioneers in switching to electronic voting (e.g., Rodrigues-Filho et al. 2006; Kumar 2008). Furthermore, one third of the countries testing electronic voting are in Latin America. What explains both of these trends?Carnegie Corporation of New York; John S. and James L. Knight Foundation; Pew Charitable Trust
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Does synaesthesia age? Changes in the quality and consistency of synaesthetic associations
Developmental grapheme-colour synaesthesia is a rare condition in which colours become automatically paired with letters or digits in the minds of certain individuals during childhood, and remain paired into adulthood. Although synaesthesia is well understood in younger adults almost nothing is known about synaesthesia in aging. We present the first evidence that aging desaturates synaesthetic colours in the minds of older synaesthetes, and we show for the first time that aging affects the key diagnostic measure of synaesthesia (consistency of colours over time). We screened ~4000 members of the general population to identify grapheme-colour synaesthetes, targeting both younger and older adults. We found proportionally fewer older than younger synaesthetes, not only because fewer older people self-reported the condition, but because fewer also passed the objective diagnostic test. We examined the roots of this apparent decline in grapheme-colour synaesthesia, finding that the internal mental colours of synaesthetes become less saturated in older subjects, and importantly, that low-saturated colours are linked with test-failure. We discuss what these findings mean for a novel field of aging and synaesthesia research, in terms of the lifespan development of synaesthesia and how best to diagnose synaesthesia in later life
New Linear Systems for 2D Poincare Supergravities
A new linear system is constructed for Poincar\'e supergravities in two
dimensions. In contrast to previous results, which were based on the conformal
gauge, this linear system involves the topological world sheet degrees of
freedom (the Beltrami and super-Beltrami differentials). The associated
spectral parameter likewise depends on these and is itself subject to a pair of
differential equations, whose integrability condition yields one of the
equations of motion. These results suggest the existence of an extension of the
Geroch group mixing propagating and topological degrees of freedom on the world
sheet. We also develop a chiral tensor formalism for arbitrary Beltrami
differentials, in which the factorization of diffeomorphisms is always
manifest.Comment: 26 pages, report DESY93-12
“Venericardia” patagonica é uma das espécies de bivalves mais comuns presentes no Oligoceno superior–Mioceno médio da Patagônia
‘Venericardia’ patagonica is one of the most common bivalve species represented in the late Oligocene–middle Miocene of Patagonia. Previous authors recognized two contrasting morphologies within this species based on sculpture and outline. An Elliptic Fourier Analysis was performed, using the anterior view of 95 specimens. A Principal Component Analysis was carried out with the Fourier coefficients. The results show two well differentiated groups, based on development of the convexity, each of which could correspond to the mature male and female, as is proposed for other carditids. The females have more bulky shells, with maximum convexity at the centre of valves. The males have less bulky shells, with a sharp ventral edge. These differences correlate with sculpture (more pronounced in males) and size of specimens (larger in females).Autores prévios reconheceram duas diferentes morfologias dentro dessa espécie a partir de sua ornamentação externa e contorno em vista lateral. Realizaram-se análises de morfometria geométrica, utilizando Contornos Elípticos de Fourier, capturando o contorno da vista anterior das valvas de 95 espécimes e de Componentes Principais dos Coeficientes de Fourier. Os resultados mostraram dois grupos bem diferenciados, baseados na convexidade das valvas, os quais corresponderiam a machos e fêmeas, como é proposto para outros carditídeos. As fêmeas teriam conchas mais volumosas, com sua convexidade máxima próxima ao centro das valvas, enquanto os machos possuem conchas menos abauladas, com a convexidade máxima próxima à margem ventral. Estas diferenças se correlacionam com outras na ornamentação externa (mais pronunciada nos machos) e no tamanho dos exemplares (maior nas fêmeas).Fil: Perez, Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Alvarez, Maximiliano Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: del Río, Claudia Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin
AAPOR Report on Big Data
In recent years we have seen an increase in the amount of statistics in society describing different phenomena based on so called Big Data. The term Big Data is used for a variety of data as explained in the report, many of them characterized not just by their large volume, but also by their variety and velocity, the organic way in which they are created, and the new types of processes needed to analyze them and make inference from them. The change in the nature of the new types of data, their availability, the way in which they are collected, and disseminated are fundamental. The change constitutes a paradigm shift for survey research.There is a great potential in Big Data but there are some fundamental challenges that have to be resolved before its full potential can be realized. In this report we give examples of different types of Big Data and their potential for survey research. We also describe the Big Data process and discuss its main challenges
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