Formulação não-linear geométrica para análise de cascas usando elementos finitos tridimensionais degenerados

Apresenta-se neste trabalho uma formulas50 Lagrangeana total para análise nao-linear geométrica de estruturas de cascas utilizando-se elementos'finitos tridimensionais degenerados. A geometria do elemento é representada pelas normais e coordenadas dos nós da superficie média. O campo de deslocamentos permite a considerasáo de grandes rotasoes, e é descrito a partir das transla~oesd os nós da superficie média e de duas rotasoes das normais em torno de eixos locais. Emprega-se um esquema de transformacáo seletiva destas rotasoes para o sistema global de referencia, o que possibilita a análise de estruturas definidas por superficies poliédricas.A total Lagrangian formulation for geometrically non-linear analysis of sheli structures using three-dimensional degenerated elements is presented. The geometric definition of the element is given by the normais and coordinates of the mid-surface nodes. The displacement field allows the consideration of large rotations and, is described by the translations of the midsurface nodes and two rotations of the normais about local axes. A selective transformation scheme of the rotation, from local to global axes, is employed in order to extend this procedure to the case of sheii structures defined by folded surfaces.Peer Reviewe

Parallel structurally-symmetric sparse matrix-vector products on multi-core processors

We consider the problem of developing an efficient multi-threaded implementation of the matrix-vector multiplication algorithm for sparse matrices with structural symmetry. Matrices are stored using the compressed sparse row-column format (CSRC), designed for profiting from the symmetric non-zero pattern observed in global finite element matrices. Unlike classical compressed storage formats, performing the sparse matrix-vector product using the CSRC requires thread-safe access to the destination vector. To avoid race conditions, we have implemented two partitioning strategies. In the first one, each thread allocates an array for storing its contributions, which are later combined in an accumulation step. We analyze how to perform this accumulation in four different ways. The second strategy employs a coloring algorithm for grouping rows that can be concurrently processed by threads. Our results indicate that, although incurring an increase in the working set size, the former approach leads to the best performance improvements for most matrices.Comment: 17 pages, 17 figures, reviewed related work section, fixed typo

Estratégia h-adaptativa para a análise elasto-plástica bidimensional

Neste trabalho apresenta-se uma estratégia h-adaptativa para problemas de elasticidade bidimensional, discretizados por elementos finitos triangulares lineares, considerando a nao linearidade do material. Esta estratégia é baseada na técnica de remalhamento (remeshing) onde, através de estimativa de erro a posteriori, se prediz o tamanho do elemento necessário para atingir um nível de precisao pré-especificado. O comportamento nao linear do material é tratado através do modelo de subcamadas, nao se limitando portanto a modelos bilineares.Peer Reviewe

Estratégia h-adaptativa para a análise elasto-plástica bidimensional

Neste trabalho apresenta-se uma estratégia h-adaptativa para problemas de elasticidade bidimensional, discretizados por elementos finitos triangulares lineares, considerando a nao linearidade do material. Esta estratégia é baseada na técnica de remalhamento (remeshing) onde, através de estimativa de erro a posteriori, se prediz o tamanho do elemento necessário para atingir um nível de precisao pré-especificado. O comportamento nao linear do material é tratado através do modelo de subcamadas, nao se limitando portanto a modelos bilineares.Peer Reviewe

The RNA-binding protein, ZFP36L2, influences ovulation and oocyte maturation

ZFP36L2 protein destabilizes AU-rich element-containing transcripts and has been implicated in female fertility. In the C57BL/6NTac mouse, a mutation in Zfp36l2 that results in the decreased expression of a form of ZFP36L2 in which the 29 N-terminal amino acid residues have been deleted, ΔN-ZFP36L2, leads to fertilized eggs that arrest at the two-cell stage. Interestingly, homozygous ΔN-Zfp36l2 females in the C57BL/6NTac strain release 40% fewer eggs than the WT littermates (Ramos et al., 2004), suggesting an additional defect in ovulation and/or oocyte maturation. Curiously, the same ΔN-Zfp36l2 mutation into the SV129 strain resulted in anovulation, prompting us to investigate a potential problem in ovulation and oocyte maturation. Remarkably, only 20% of ΔN-Zfp36l2 oocytes in the 129S6/SvEvTac strain matured ex vivo, suggesting a defect on the oocyte meiotic maturation process. Treatment of ΔN-Zfp36l2 oocytes with a PKA inhibitor partially rescued the meiotic arrested oocytes. Furthermore, cAMP levels were increased in ΔN-Zfp36l2 oocytes, linking the cAMP/PKA pathway and ΔN-Zfp36l2 with meiotic arrest. Since ovulation and oocyte maturation are both triggered by LHR signaling, the downstream pathway was investigated. Adenylyl cyclase activity was increased in ΔN-Zfp36l2 ovaries only upon LH stimulation. Moreover, we discovered that ZFP36L2 interacts with the 3′UTR of LHR mRNA and that decreased expression levels of Zfp36l2 correlates with higher levels of LHR mRNA in synchronized ovaries. Furthermore, overexpression of ZFP36L2 decreases the endogenous expression of LHR mRNA in a cell line. Therefore, we propose that lack of the physiological down regulation of LHR mRNA levels by ZFP36L2 in the ovaries is associated with anovulation and oocyte meiotic arrest.Fil: Ball, Christopher B.. University of North Carolina; Estados UnidosFil: Rodriguez, Karina F.. National Institutes of Health; Estados UnidosFil: Stumpo, Deborah J.. National Institutes of Health; Estados UnidosFil: Ribeiro Neto, Fernando. National Institutes of Health; Estados UnidosFil: Korach, Kenneth S.. National Institutes of Health; Estados UnidosFil: Blackshear, Perry J.. University of Duke; Estados Unidos. National Institutes of Health; Estados UnidosFil: Birnbaumer, Lutz. National Institutes of Health; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ramos, Silvia B. V.. University of North Carolina; Estados Unido

Lifestyle and wellbeing: Exploring behavioral and demographic covariates in a large US sample

Using data from a nationally representative sample of 46,179 US adults from the Gallup-Healthways Wellbeing Index, we investigate covariates of four subjective mental wellbeing dimensions spanning evaluative (life satisfaction), positive affective (happiness), negative affective (worry), and eudaimonic wellbeing. Negative covariates were generally more strongly correlated with the four dimensions than positive covariates, with depression, poor health, and loneliness being the greatest negative correlates and excellent health and older age being the greatest positive correlates. We reproduce previous evidence for a “midlife crisis” around age 50 across the four wellbeing dimensions. Notably, although salutogenic behaviors (diet, exercise, socializing) correlated with greater wellbeing, there were diminishing benefits beyond thresholds of about four hours a day spent socializing, four days per week of consuming fruits and vegetables, and four days per week of exercising. Findings suggest that wellbeing is easier lost than gained, underscore the influence that relatively malleable lifestyle factors have on wellbeing, and stress the importance of multidimensional measurement for public policy

Bound states in the dynamics of a dipole in the presence of a conical defect

In this work we investigate the quantum dynamics of an electric dipole in a $(2+1)$-dimensional conical spacetime. For specific conditions, the Schr\"odinger equation is solved and bound states are found with the energy spectrum and eigenfunctions determined. We find that the bound states spectrum extends from minus infinity to zero with a point of accumulation at zero. This unphysical result is fixed when a finite radius for the defect is introduced.Comment: 4 page

Robótica'2001 - Festival Nacional de Robótica

O ROBÓTICA’2001 – Festival Nacional de Robótica visa promover desenvolvimentos técnicos e científicos na área da Robótica Móvel e áreas afins (electrónica, mecânica, programação, visão por computador, inteligência artificial, navegação, controlo, etc) através de um problema motivador, a ser resolvido por diferentes grupos de investigadores e estudantes. Procura-se ainda difundir a Ciência e a Tecnologia junto do público em geral e dos jovens em particular, nomeadamente motivando estes últimos para a aprendizagem experimental da Ciência. O objectivo principal dos participantes no evento deverá ser pois aprender e partilhar a sua aprendizagem com os colegas, tendo em vista a evolução da Robótica. Este evento consistiu em três actividades paralelas: uma competição de robótica móvel (em duas modalidades), um encontro científico e ainda várias demonstrações de outros robôs móveis e/ou autónomos

Mobile robot competitions: fostering advances in research, development and education in robotics

Mobile robot competitions are events well suited to experimentation, research and development in many areas concerned with science and technology, ranging from material science to artificial intelligence. Aware of this fact, and for several years now, some Portuguese Universities have been involving some of their Engineering and Computer Science students in such contests, namely those of international level. The performance has been improving both in terms of the results and prizes obtained and the increasingly elaborate technical solutions developed by the teams. The importance recognised in these events has led the authors to submit to the Portuguese Government a proposal for an annual Festival of this kind in Portugal. This paper points out the advances in research, technology and education, which result from this type of events

Effects of Resistance Exercise on Endothelial Progenitor Cell Mobilization in Women

This study aimed to determine the effect of a single bout of resistance exercise at different intensities on the mobilization of circulating EPCs over 24 hours in women. In addition, the angiogenic factors stromal cell-derived factor 1 (SDF-1α), vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1-alpha (HIF-1α) and erythropoietin (EPO) were measured as potential mechanisms for exercise-induced EPCs mobilization. Thirty-eight women performed a resistance exercise session at an intensity of 60% (n = 13), 70% (n = 12) or 80% (n = 13) of one repetition maximum. Each session was comprised of three sets of 12 repetitions of four exercises: bench press, dumbbell curl, dumbbell squat, and standing dumbbell upright row. Blood was sampled at baseline and immediately, 6 hours, and 24 hours post-exercise. Circulating EPC and levels of VEGF, HIF-1α and EPO were significantly higher after exercise (P \u3c 0.05). The change in EPCs from baseline was greatest in the 80% group (P \u3c 0.05), reaching the highest at 6 hours post-exercise. The change in EPCs from baseline to 6 hours post-exercise was correlated with the change in VEGF (r = 0.492, P = 0.002) and HIF-1α (r = 0.388, P = 0.016). In general, a dose-response relationship was observed, with the highest exercise intensities promoting the highest increases in EPCs and angiogenic factors