Non-minimally coupled tachyon field with Noether symmetry under the Palatini approach

A model for a homogeneous, isotropic, flat Universe composed by dark energy and matter is investigated. Dark energy is considered to behave as a tachyon field, which is non-minimally coupled to gravity. The connection is treated as metric independent when varying the action, providing an extra term to the Lagrangian density. The self-interaction potential and coupling are naturally found by imposing a Noether symmetry to the system. We analyze the evolution of the density parameters and we compare the results obtained for the deceleration parameter, luminosity distance and Hubble parameter with those found in literature from observational data.Comment: 6 pages, 4 figures to be published in the AIP Conference Proceeding

Survey of detection techniques, mathematical models and simulation software in pedestrian dynamics

The study of pedestrian dynamics has become in the latest years an increasing field of research. A relevant number of technicians have been looking for improving technologies able to detect walking people in various conditions. Several researchers have dedicated their works to model walking dynamics and general laws. Many studiers have developed interesting software to simulate pedestrian behavior in all sorts of situations and environments. Nevertheless, till nowadays, no research has been carried out to analyze all the three over-mentioned aspects. The remarked lack in literature of a complete research, pointing out the fundamental features of pedestrian detection techniques, pedestrian modelling and simulation and their tight relationships, motivates the draft of this paper. Aim of the paper is, first, to provide a schematic summary of each topic. Secondly, a more detailed description of the subjects is displayed, pointing out the advantages and disadvantages of each detection technology, the working logic of each model, outlining the inputs and the provided outputs, and the main features of the simulation software. Finally, the obtained results are summarized and discussed, in order to outline the correlation among the three explained themes

MacArthur and Frozen Chosin: An Analysis of the Press Coverage of Douglas MacArthur during the Battle of Chosin Reservoir

The Korean war included the rapid deterioration of the military career of one of America\u27s most decorated generals. During the cold Korean November of 1950, General Douglas MacArthur’s 8th Army and X Corps army units were in a race along the Korean coasts toward the border with China. Unlike previous endeavors, MacArthur’s “Home by Christmas” offensive ended in defeat, with the United Nation’s forces retreating back over the 38th Parallel after a Chinese counter attack. The Battle of Chosin Reservoir took place during this offensive and lasted from 27 November to 13 December, 1950. Most scholars agree that in retrospect MacArthur’s advance was overzealous, while some maintain that it was the only move, which would have brought the war to a swift and decisive conclusion. The goal of this paper was to investigate how the major press in the United States was writing about General MacArthur during the Battle of Chosin Reservoir. The press coverage during the Battle of Chosin Reservoir helped to ensure that MacArthur’s legacy included debate and polarization rather than his unanimous admiration as a war hero

Evaluation of the brain-derived neurotrophic factor, nerve growth factor and memory in adult rats survivors of the neonatal meningitis by Streptococcus agalactiae

AbstractStreptococcus agalactiae (GBS) is a major cause of severe morbidity and mortality in neonates and young infants, causing sepsis, pneumonia and meningitis. The survivors from this meningitis can suffer serious long-term neurological consequences, such as, seizures, hearing loss, learning and memory impairments. Neurotrophins, such as nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) control the neuronal cell death during the brain development and play an important role in neuronal differentiation, survival and growth of neurons. Neonate Wistar rats, received either 10μL of sterile saline as a placebo or an equivalent volume of GBS suspension at a concentration of 1×106cfu/mL. Sixty days after induction of meningitis, the animals underwent behavioral tests, after were killed and the hippocampus and cortex were retired for analyze of the BDNF and NGF levels. In the open-field demonstrated no difference in motor, exploratory activity and habituation memory between the groups. The step-down inhibitory avoidance, when we evaluated the long-term memory at 24h after training session, we found that the meningitis group had a decrease in aversive memory when compared with the long-term memory test of the sham group. BDNF levels decreased in hippocampus and cortex; however the NGF levels decreased only in hippocampus. These findings suggest that the meningitis model could be a good research tool for the study of the biological mechanisms involved in the behavioral alterations secondary to GBS meningitis

Cognitive and affective factors affecting task difficulty in efl reading

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e ExpressãoO presente estudo tem por objetivo investigar, através de atividades, quatro diferentes tipos de operações mentais - Identificar, Deduzir, Definir e Reordenar, em três categorias da taxionomia de Bloom, com o propósito de: (1) descobrir a ordem de dificuldade destas operações no contexto do ensino de língua estrangeira, (2) verificar o que os alunos fazem enquanto trabalham em um exercício, e (3) avaliar o esforço cognitivo destes alunos. Todos as unidades de exercícios eram de padrão semelhante, consistindo de três elementos básicos: o Pré-exercício feito por toda a classe sob a orientação da pesquisadora, o Exercício I feito em duplas pelos participantes da pesquisa, e o Exercício II feito pelos alunos em duplas. O Pré- exercício e o Exercício I eram semelhantes, envolvendo a mesma situação, os mesmos fatos/tópicos e o mesmo processo cognitivo. Os Exercícios II mantiveram a mesma estrutura, porém apresentaram um tópico novo. O objetivo do Pré-exercício era providenciar um contexto onde os alunos pudessem trabalhar as dificuldades do Exercício I previamente, e assim permitir à pesquisadora reduzir o nível de difficuldade dos exercícios e dar assistência apropriada aos sujeitos para a execução do Exercício I. Ao término dos Exercícios I e II, foi passado um questionário para obter a opinião dos alunos sobre as dificuldades relacionadas a fatores tais como: Vocabulário, Familiaridade, Pré-Exercício e Português, uma tentativa de separar as dificuldades lingüísticas das dificuldades relacionadas às operações mentais. Como não foi possível estabelecer nenhuma hierarquia quanto ao grau de dificuldade dos exercícios e foram poucas as correlações obtidas entre as variáveis do questionário, estes fatos são, então, atribuídos a três principais fatores: a) várias operações mentais ocorrendo ao mesmo tempo, b) fatores inerentes a cada exercício e c) fatores afetivos

Cosmological models with interacting components and mass-varying neutrinos

A model for a homogeneous and isotropic spatially flat Universe, composed of baryons, radiation, neutrinos, dark matter and dark energy is analyzed. We infer that dark energy (considered to behave as a scalar field) interacts with dark matter (either by the Wetterich model, or by the Anderson and Carroll model) and with neutrinos by a model proposed by Brookfield et al.. The latter is understood to have a mass-varying behavior. We show that for a very-softly varying field, both interacting models for dark matter give the same results. The models reproduce the expected red-shift performances of the present behavior of the Universe.Comment: 8 pages, 5 figures, to be published in Gravitation and Cosmolog