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Descrição variacional de sistemas formados por átomos de 4He; Variational description of systems made of 4He atoms

Vinicius Zampronio Pedroso
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/08/2014 Português
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We present a trial wave function to describe systems formed from 4He atoms. This function is able to describe the system in the liquid and solid phases, it is translationally invariant and satisfies the Bose-Einstein statistics. This wave function depends on a set of auxiliary variables integrated all over the space and favors the exchange between particles, mainly at higher densities where it is more important. We also calculated the equation of state and the pair distribution function of the liquid and solid phases of the system and results are in good agreement with the experimental data; Apresentamos uma função de onda tentativa para descrever sistemas de átomos de 4He. Esta função é capaz de descrever o sistema nas fases sólida e liquida, é translacionalmente invariante e satisfaz a estatística de Bose-Einstein. A função proposta depende de um conjunto de variáveis auxiliares integradas em todo o espaço e favorece os processos de troca de partículas, principalmente para densidades mais altas onde ela é importante. Calculamos a equação de estado e a função de distribuição radial das fases liquida e sólida do sistema e obtivemos um ótimo acordo com dados experimentais

O ajudante de acção directa na medida de rendimento social de inserção: um estudo de caso

Ribeiro, Ana Cláudia Dias
Fonte: Instituto Superior de Ciências Sociais e Políticas Publicador: Instituto Superior de Ciências Sociais e Políticas
Tipo: Dissertação de Mestrado
Publicado em 26/03/2010 Português
Relevância na Pesquisa
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Dissertação de Mestrado em Política Social; A prevenção de situações de pobreza e exclusão bem como a promoção da autonomia e integração pessoal, social e comunitária constituem o objectivo primordial da Medida de Política Social de Rendimento Social de Inserção. Este trabalho avalia o papel do Ajudante de Acção Directa na execução da Medida acima referida nos protocolos de acompanhamento de indivíduos e famílias estabelecidos entre o Instituto da Segurança Social e Instituições do Distrito de Setúbal, ao nível do seu desempenho profissional, enquanto interventor social integrado em equipas multidisciplinares, na relação com o Gestor de Caso e na relação com o sistema cliente. Para a sua concretização, recolhemos dados por via da observação e da aplicação de inquéritos por questionário aplicados a 73 Ajudantes de Acção Directa e 43 Gestores de Caso, e por entrevista realizada a 34 Ajudantes de Acção Directa. Foi possível identificar o grau de adequabilidade entre o descritivo funcional e a prática verificada, bem como elencar as potencialidades, constrangimentos e formas de superação dos mesmos referentes ao Ajudante de Acção Directa na execução da Medida RSI. Percebemos que este interventor social representa uma figura de proximidade determinante na prossecução dos objectivos e metodologias de intervenção definidas para esta Medida; The prevention of poverty situations...

Auditoria às fichas de descrições de funções da empresa Carmona,S.A. como preparação de um processo de avaliação de desempenho

Lobita, Vera Sofia Antunes Carmona
Fonte: Último nome, Primeiro nome. data de publicação. "Título". Dissertação de Mestrado. Universidade de Lisboa. Instituto Superior de Economia e Gestão. Publicador: Último nome, Primeiro nome. data de publicação. "Título". Dissertação de Mestrado. Universidade de Lisboa. Instituto Superior de Economia e Gestão.
Tipo: Dissertação de Mestrado
Publicado em //2013 Português
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Mestrado em Gestão de Recursos Humanos; O presente trabalho teve como objetivo auditar as fichas de descrição de funções da Carmona, S.A. e, desta forma, criar condições para o desenvolvimento de um sistema de avaliação de desempenho que permita medir o contributo de cada colaborador no âmbito das suas tarefas diárias: obter classificações objetivas, com o menor erro possível, assente em critérios claros e rigorosos, de forma a reconhecer e premiar o desempenho de cada colaborador e, ao mesmo tempo, ajudá-lo no seu alinhamento com os seus objetivos concretos. Em termos metodológicos, o projeto, assente numa revisão bibliográfica pertinente, procurou encontrar o modelo mais adequado à realidade da Carmona, S.A.. Foi feito um estudo documental no que respeita à análise e descrição de funções, para se perceber o que se podia adequar a este projeto e quais as necessidades de melhoria para que este fosse desenvolvido da forma mais adequada à realidade desta empresa e do mercado em que se insere.; This study aimed to audit Carmona, S.A.’s function description records, and create the necessary conditions to develop a performance evaluation system. This system shall measure each collaborator’s contribution...

From fold predictions to function predictions: automation of functional site conservation analysis for functional genome predictions.

Zhang, B.; Rychlewski, L.; Pawłowski, K.; Fetrow, J. S.; Skolnick, J.; Godzik, A.
Fonte: Cold Spring Harbor Laboratory Press Publicador: Cold Spring Harbor Laboratory Press
Tipo: Artigo de Revista Científica
Publicado em /05/1999 Português
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A database of functional sites for proteins with known structures, SITE, is constructed and used in conjunction with a simple pattern matching program SiteMatch to evaluate possible function conservation in a recently constructed database of fold predictions for Escherichia coli proteins (Rychlewski L et al., 1999, Protein Sci 8:614-624). In this and other prediction databases, fold predictions are based on algorithms that can recognize weak sequence similarities and putatively assign new proteins into already characterized protein families. It is not clear whether such sequence similarities arise from distant homologies or general similarity of physicochemical features along the sequence. Leaving aside the important question of nature of relations within fold superfamilies, it is possible to assess possible function conservation by looking at the pattern of conservation of crucial functional residues. SITE consists of a multilevel function description based on structure annotations and structure analyses. In particular, active site residues, ligand binding residues, and patterns of hydrophobic residues on the protein surface are used to describe different functional features. SiteMatch, a simple pattern matching program, is designed to check the conservation of residues involved in protein activity in alignments generated by any alignment method. Here...

A Steady-State Transfer Function Analysis of Portions of the Circulatory System Using Indicator Dilution Techniques*

Coulam, Craig M.; Warner, Homer R.; Marshall, Hiram W.; Bassingthwaighte, James B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1967 Português
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A digital computer program has been developed whereby the distribution of dye-particle transit times across circulatory pathways can be found from recordings of upstream and downstream indicator-dilution curves. This distribution or transfer function is computed from Fourier-series representations of the upstream and downstream indicator curves and makes possible, for the first time, the calculation of transit-time distributions independent of the effects of recirculating dye. Since a discontinuity is introduced into the tails of the upstream and downstream curves at the end of sampling, the method requires an iterative approach in the termination of the upstream and downstream curves. The accuracy of the calculated distribution pattern is determined by comparison of the recorded downstream curve with the results of the convolution of the recorded upstream curve and computed transfer function. Effects of noise, bandwidth and sampling rate have been investigated through the use of analog computer models of the circulatory pathways. These studies show that the transfer-function description is limited by the bandwidth of the upstream (input) curve. Noise, or variations in magnitude and phase angle of input- and output-curve frequencies...

The force-interval relationship of the left ventricle: a quantitative description in patients with ischemic heart disease

Ritchie, R.; Wuttke, R.; Hii, J.; Jarrett, R.; Carey, A.; Horowitz, J.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Artigo de Revista Científica
Publicado em //1995 Português
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Quantitative descriptions of the mechanical restitution curve as a description of variability in ventricular performance with coupling interval in isolated tissue preparations are widely available. In humans, however, in vivo examination of the force-interval relationship is restricted to test pulse intervals shorter than the sinus cycle length (i.e., incomplete mechanical restitution). The primary objectives in this investigation were therefore to examine this aspect of mechanical restitution in patients with ischemic heart disease and to develop a quantitative description of the phenomenon. Mechanical restitution curves were constructed in 40 patients, most of whom had well-preserved left ventricular (LV) systolic function, undergoing diagnostic cardiac catheterization for the investigation of chest pain, using a single premature test pulse interval during baseline atrial pacing. The mechanical restitution curve, the relationship between LV + dP/dtmax and test pulse interval, was fitted to a rectangular hyperbolic function. From this, the parameter c, the calculated proportional decrease in LV + dP/dtmax at 60% of the resting cycle length, was derived. The mechanical restitution curve-fitting model (involving determination of c) satisfactorily described the force-interval relationship in 37 of the 40 patients studied (as a rectangular hyperbola in 31 and with simple linear regression in 6 patients). The refractory period of the atria/atrioventricular node limited accurate use of the model in the remaining three patients. The parameter c was inversely proportional to both baseline atrial pacing cycle length (P < .001) and LV ejection fraction (P < .02) In patients with normal LV ejection fractions...

Electronic Structure Description of the cis-MoOS Unit in Models for Molybdenum Hydroxylases

Doonan, C.; Rubie, N.; Peariso, K.; Harris, H.; Knottenbelt, S.; George, G.; Young, C.; Kirk, M.
Fonte: Amer Chemical Soc Publicador: Amer Chemical Soc
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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The molybdenum hydroxylases catalyze the oxidation of numerous aromatic heterocycles and simple organics and, unlike other hydroxylases, utilize water as the source of oxygen incorporated into the product. The electronic structures of the cis-MoOS units in CoCp2[TpiPrMoVOS(OPh)] and TpiPrMoVIOS(OPh) (TpiPr = hydrotris(3-isopropylpyrazol-1-yl)borate), new models for molybdenum hydroxylases, have been studied in detail using S K-edge X-ray absorption spectroscopy, vibrational spectroscopy, and detailed bonding calculations. The results show a highly delocalized Mo=S pi* LUMO redox orbital that is formally Mo(dxy) with approximately 35% sulfido ligand character. Vibrational spectroscopy has been used to quantitate Mo-Ssulfido bond order changes in the cis-MoOS units as a function of redox state. Results support a redox active molecular orbital that has a profound influence on MoOS bonding through changes to the relative electro/nucleophilicity of the terminal sulfido ligand accompanying oxidation state changes. The bonding description for these model cis-MoOS systems supports enzyme mechanisms that are under orbital control and dominantly influenced by the unique electronic structure of the cis-MoOS site. The electronic structure of the oxidized enzyme site is postulated to play a role in polarizing a substrate carbon center for nucleophilic attack by metal activated water and acting as an electron sink in the two-electron oxidation of substrates.; Christian J. Doonan...

Star formation rate distributions: Inadequacy of the Schechter function

Salim, S.; Lee, J.C.
Fonte: The American Astronomical Society Publicador: The American Astronomical Society
Tipo: Artigo de Revista Científica
Português
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In this paper, we posit that galaxy luminosity functions (LFs) come in two fundamentally different types depending on whether the luminosity traces galaxy stellar mass or its current star formation rate (SFR). $ extit{Mass function types}$ reflect the older stars and therefore the stellar mass distribution, while $ extit{SFR function types}$ arise from the young stars and hence the distribution of SFRs. Optical and near-infrared LFs are of the mass function type and are well fit by a Schechter function (power law with an exponential cutoff at the bright end). In contrast, LFs of the SFR function type are of a different form, one that cannot be adequately described by a Schechter function. We demonstrate this difference by generating SFR distributions for mock samples of galaxies drawn from a Schechter stellar mass distribution along with established empirical relations between the SFR and stellar mass. Compared with the Schechter function, SFR distributions have a shallower decline at the bright end, which can be traced to the large intrinsic scatter of SFRs at any given stellar mass. A superior description of SFR distributions is given by the "Saunders" function, which combines a power law with a Gaussian at the high end. We show that the Schechter-like appearance of UV and Hα LFs...

Ensinar: "então, é função de quem?" Atuação do professor interlocutor na educação de surdos da rede estadual paulista; Teaching: "then, whose function is this?" Interlocutor teacher performance in deaf education of São Paulo state public schools

Lopes, Mara Aparecida de Castilho
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/04/2015 Português
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A contratação de professores interlocutores na rede estadual de ensino de São Paulo tem gerado dúvidas sobre sua função no processo educacional de estudantes surdos, pois os documentos estaduais não delimitam sua atuação de forma explícita. Políticas federais estabelecem que surdos inseridos no ensino regular sejam acompanhados por intérpretes de língua de sinais, o que induz à compreensão de que o professor interlocutor deve assumir tal função. A partir dos pressupostos teórico-metodológicos da Psicologia Histórico-Cultural, o presente trabalho tem o objetivo de identificar a função social do professor interlocutor. A tese é composta por dois estudos: no Estudo 1 analisa-se um material em vídeo, disponibilizado pela Secretaria de Educação para reflexão coletiva da função do professor interlocutor, a fim de identificar o significado social da atividade desse profissional. No Estudo 2 analisamos o processo de atribuição de sentido pessoal à atividade de professor interlocutor, em profissionais atuantes em um município do interior paulista. Foram entrevistados 21 professores interlocutores, individualmente, com apoio de roteiro semiestruturado; os participantes também foram submetidos a uma avaliação de fluência na Língua Brasileira de Sinais. Para a análise dos dados...

Multiple Description Coding : proposed methods and video application

Moradi, Saeed
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 731005 bytes; application/pdf
Português
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Multiple description coding (MDC) has received a lot of attention recently, and has been studied widely and extended to many demanding applications such as speech and video. MDC is a coding technique that generates correlated descriptions of the source stream for transmitting over a diversity system with several channels. The objective of this diversity system is to overcome channel impairments and provide more reliability. In the context of lossy source coding and quantization, a multiple description quantization system usually consists of multiple channels, side encoders to quantize the source samples and send over different channels, and side and central decoders to reconstruct the source. We propose two multiple description quantization schemes in order to design the codebooks and partitions of side and central quantizers of a multiple description system with two channels. The applied framework originated in the multiple description quantization via Gram-Schmidt orthogonalization approach. The basic idea of our proposed schemes is to minimize a Lagrangian cost function by an iterative technique which jointly designs side codebooks and partitions. Our proposed methods perform very closely to the optimum MD quantizer with considerably less complexity. We also propose a multiple description video coding technique motivated by human visual perception. We employ two simple parameters as a measure of the perceptual tolerance of discrete cosine transform (DCT) blocks against visual distortion. We duplicate the essential information such as motion vectors and some low-frequency DCT coefficients of prediction errors into each description...

Über den bau und die funktion der valvula vaginalis der bienenkönigin (Apis mellifica L.); On structure and function of the valvula vaginalis of the queen honeybee (Apis mellifera L.); Sur la structure et la fonction de la valve vaginale de la reine des abeilles (Apis mellifeca L.); Sulla struttura e la funzione della valvula vaginalis della regina d'ape (Apis mellifica L.)

Fyg, Werner
Fonte: INRA - Instituto Nacional de Investigação Agronômica da França Publicador: INRA - Instituto Nacional de Investigação Agronômica da França
Tipo: Journal Article-postprint
Português
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The valve-fold of the queen honeybee is an epithe1ian fold of the ventral vaginal wall which is interlaced with ascending muscle fibres. The valve-fold projects into the lumen of the vagina like a tongue-shaped roll just behind the caudal end of the median oviduct and directly above the sternal antecosta of the VII. segment. Opinions about the function of this fold are dlsagreeing. A short description of the histological structure of the valve-fold is given. Furthermore, reference is made to a premature, progressive degeneration and calcification of the valve-fold's musculature in most of the queen honeybees, dependent on age. In discussions concerning the function of the valve-fold, these causally not clarified degeneration processes must be considered.

Métodos Monte Carlo Quântico e Outer Valence Green's function aplicados na obtenção de energias de ionização de sistemas atômicos e moleculares e na construção e interpretação de diagramas de correlação; Quantum Monte Carlo and Outer Valence Green's function methods applied to obtain ionization energies of atomic and molecular systems and to construction and interpretation of correlation diagrams

Leandro de Abreu
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/03/2011 Português
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Este trabalho avaliou o cálculo de energias de ionização verticais e as possibilidades de construção e interpretação de diagramas de correlação através do uso dos métodos Monte Carlo Quântico (MCQ) e Outer Valence Green¿s Function (OVGF). O trabalho foi dividido em quatro partes: Energias de ionização simples: Avaliou-se a capacidade dos métodos MCQ e OVGF em descrever os valores de energia de ionização de valência e de caroço e testou-se o uso de funções de onda relaxadas. A faixa dos desvios observados obtidas com o método Monte Carlo Quântico de Difusão (MCQD), em relação aos valores experimentais, é comparável a de outros métodos, como DFT (Teoria do Funcional de Densidade - Density Functional Theory) e CCGF (Funções de Green com Pares Acoplados - Coupled-Cluster Green¿s Function), 0,01 a 2 eV, e verificou-se que uso das funções de onda relaxadas é importante na descrição das ionizações de caroço. Energias de ionização sucessivas: Estimou-se as energias de ionização sucessivas dos elementos do 2º período a partir das energias orbitais do sistema neutro e comparou-se com resultados obtidos através dos métodos MCQ utilizando-se a função de onda do sistema não-ionizado. Pode-se demonstrar a falha das energias orbitais em descrever as energias de ionização sucessivas e obter correções com o uso dos métodos MCQ. Diagramas de correlação: Construíram-se diagramas de energia eletrônica total e de correlação quantitativos utilizando energia de ionização como binding energy para moléculas do tipo BAB (H2O e Li2O) através do uso dos métodos MCQ. Foram construídos diagramas de cargas parciais de Bader através das distribuições discretas de carga obtidas com os métodos MCQ para tentar interpretar os diagramas de correlação...

Estimação não-parametrica para função de covariancia de processos gaussianos espaciais; Nonparametric estimation for covariance function of spatial gaussian processes

Jose Clelto Barros Gomes
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/04/2009 Português
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O desafio na modelagem de processos espaciais está na descrição da estrutura de covariância do fenômeno sob estudo. Um estimador não-paramétrico da função de covariância foi construído de forma a usar combinações lineares de funções B-splines. Estas bases são usadas com muita frequência na literatura graças ao seu suporte compacto e a computação tão rápida quanto a habilidade de criar aproximações suaves e apropriadas. Verificouse que a função de covariância estimada era definida positiva por meio do teorema de Bochner. Para a estimação da função de covariância foi implementado um algoritmo que fornece um procedimento completamente automático baseado no número de funções bases. Então foram realizados estudos numéricos que evidenciaram que assintoticamente o procedimento é consistente, enquanto que para pequenas amostras deve-se considerar as restrições das funções de covariância. As funções de covariâncias usadas na estimação foram as de exponencial potência, gaussiana, cúbica, esférica, quadrática racional, ondular e família de Matérn. Foram estimadas ainda covariâncias encaixadas. Simulações foram realizadas também a fim de verificar o comportamento da distribuição da afinidade. As estimativas apresentaram-se satisfatórias; The challenge in modeling of spatials processes is in description of the framework of covariance of the phenomenon about study. The estimation of covariance functions was done using a nonparametric linear combinations of basis functions B-splines. These bases are used frequently in literature thanks to its compact support and fast computing as the ability to create smooth and appropriate approaches There was positive definiteness of the estimator proposed by the Bochner's theorem. For the estimation of the covariance functions was implemented an algorithm that provides a fully automated procedure based on the number of basis functions. Then numerical studies were performed that showed that the procedure is consistent assynthotically. While for small samples should consider the restrictions of the covariance functions...

Assessment of longitudinal myocardial stiffness is not enough to evaluate diastolic function.

Donato, Martín; Gelpi, Ricardo Jorge
Fonte: Japanese Circulation Soc Publicador: Japanese Circulation Soc
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Português
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In the 1960 s, the first studies of diastolic function appeared and from there the interest in this phase of the cardiac cycle increased. Such interest has continued to the present day, when systole and diastole are equally considered. It should be added that in the past 2 decades the prevalence of heart failure with preserved ejection fraction has increased, and the prognosis of those patients with diastolic dysfunction is poor. Detailed study of the diastolic function, not only in intact animals or in patients, but in isolated organs as well, and even at the cellular level, has enabled clear differentiation of 2 phases in the diastolic component: isovolumic relaxation, and myocardial stiffness. For several years these 2 phases were independently studied, but it was later observed that interaction between them does exist, and that it can modify not only ventricular filling, but ventricular contraction as well. More specifically, it was found that incomplete relaxation can be completed during ventricular filling, increasing myocardial stiffness. However, all of those studies have considered longitudinal myocyte changes, and did not assess modifications that could occur in the transverse axis. Consideration of changes in the longitudinal and transverse axes of the myocytes is particularly important when we address the fact that the structure of the ventricular wall and its cellular distribution is based on helicoidal muscular beams that intercross...

Wigner-function description of EPR experiment

Franco, Riccardo
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/01/2007 Português
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We provide a detailed description of the EPR paradox (in the Bohm version) for a two qubit-state in the discrete Wigner function formalism. We compare the probability distributions for two qubit relevant to simultaneously-measurable observables (computed from the Wigner function) with the probability distributions representing two perfectly-correlated classic particles in a discrete phase-space. We write in both cases the updating formulae after a measure, thus obtaining a mathematical definition of \textit{classic collapse} and \textit{quantum collapse}. We study, with the EPR experiment, the joint probability distributions of Alice's and Bob's qubit before and after the measure, analyzing the non-local effects. In particular, we give a more precise definition of locality, which we call m-locality: we show that quantum systems may violate this kind of locality, thus preserving, in an EPR-like argument, the completeness of Quantum Mechanics.; Comment: 8 pages

Limits in the characteristic function description of non-Lindblad-type open quantum systems

Maniscalco, Sabrina
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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In this paper I investigate the usability of the characteristic functions for the description of the dynamics of open quantum systems focussing on non-Lindblad-type master equations. I consider, as an example, a non-Markovian generalized master equation containing a memory kernel which may lead to nonphysical time evolutions characterized by negative values of the density matrix diagonal elements [S.M. Barnett and S. Stenholm, Phys. Rev. A {\bf 64}, 033808 (2001)]. The main result of the paper is to demonstrate that there exist situations in which the symmetrically ordered characteristic function is perfectly well defined while the corresponding density matrix loses positivity. Therefore nonphysical situations may not show up in the characteristic function. As a consequence, the characteristic function cannot be considered an {\it alternative complete} description of the non-Lindblad dynamics.; Comment: Revised version. 4 pages, 1 figure

Towards a nonequilibrium Green's function description of nuclear reactions: one-dimensional mean-field dynamics

Rios, Arnau; Barker, Brent; Buchler, Mark; Danielewicz, Pawel
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/09/2010 Português
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Nonequilibrium Green's function methods allow for an intrinsically consistent description of the evolution of quantal many-body body systems, with inclusion of different types of correlations. In this paper, we focus on the practical developments needed to build a Green's function methodology for nuclear reactions. We start out by considering symmetric collisions of slabs in one dimension within the mean-field approximation. We concentrate on two issues of importance for actual reaction simulations. First, the preparation of the initial state within the same methodology as for the reaction dynamics is demonstrated by an adiabatic switching on of the mean-field interaction, which leads to the mean-field ground state. Second, the importance of the Green's function matrix-elements far away from the spatial diagonal is analyzed by a suitable suppression process that does not significantly affect the evolution of the elements close to the diagonal. The relative lack of importance of the far-away elements is tied to system expansion. We also examine the evolution of the Wigner function and verify quantitatively that erasing of the off-diagonal elements corresponds to averaging out of the momentum-space details in the Wigner function.; Comment: 78 pages...

The ACS Virgo Cluster Survey. XII.Tthe Luminosity Function of Globular Clusters in Early Type Galaxies

Jordan, Andres; McLaughlin, Dean; Cote, Patrick; Ferrarese, Laura; Peng, Eric; Mei, Simona; Villegas, Daniela; Merritt, David; Tonry, John; West, Michael
Fonte: Universtiy of Chicago Press: Astrophysical Journal Supplement Series Publicador: Universtiy of Chicago Press: Astrophysical Journal Supplement Series
Tipo: Artigo de Revista Científica
Português
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We analyze the luminosity function of the globular clusters (GCs) belonging to the early-type galaxies observed in the ACS Virgo Cluster Survey. We have obtained maximum likelihood estimates for a Gaussian representation of the globular cluster luminosity function (GCLF) for 89 galaxies. We have also fit the luminosity functions with an “evolved Schechter function”, which is meant to reflect the preferential depletion of low-mass GCs, primarily by evaporation due to two-body relaxation, from an initial Schechter mass function similar to that of young massive clusters in local starbursts and mergers. We find a highly significant trend of the GCLF dispersion σ with galaxy luminosity, in the sense that the GC systems in smaller galaxies have narrower luminosity functions. The GCLF dispersions of our Galaxy and M31 are quantitatively in keeping with this trend, and thus the correlation between σ and galaxy luminosity would seem more fundamental than older notions that the GCLF dispersion depends on Hubble type. We show that this narrowing of the GCLF in a Gaussian description is driven by a steepening of the cluster mass function above the classic turnover mass, as one moves to lower-luminosity host galaxies. In a Schechter-function description...

The 2dF Galaxy Redshift Survey: the bj-band galaxy luminosity function and survey selection function

Norberg, Peder; Cole, Shaun; Baugh, Carlton M; Frenk, Carlos S; Baldry, Ivan K; Bland-Hawthorn, Joss; Bridges, Terry C; Cannon, Russell; Colless, Matthew; Collins, Chris; Couch, Warrick; Cross, Nicholas J G; Dalton, Gavin; de Propris, Roberto; Driver, Sim
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
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We use more than 110 500 galaxies from the 2dF Galaxy Redshift Survey (2dFGRS) to estimate the bJ-band galaxy luminosity function at redshift z = 0, taking account of evolution, the distribution of magnitude measurement errors and small corrections for incompleteness in the galaxy catalogue. Throughout the interval -16.5 > MbJ -5log10 h > -22, the luminosity function is accurately described by a Schechter function with M*bJ -5 log10 h = -19.66 ± 0.07, α = -1.21 ± 0.03 and Φ* = (1.61 ± 0.08) × 10-2 h3 Mpc-3, giving an integrated luminosity density of ρL = (1.82 ± 0.17) × 108 h L⊙ Mpc-3 (assuming an Ω0 = 0.3, Λ0 = 0.7 cosmology). The quoted errors have contributions from the accuracy of the photometric zero-point, from large-scale structure in the galaxy distribution and, importantly, from the uncertainty in the appropriate evolutionary corrections. Our luminosity function is in excellent agreement with, but has much smaller statistical errors than, an estimate from the Sloan Digital Sky Survey (SDSS) data when the SDSS data are accurately translated to the bJ band and the luminosity functions are normalized in the same way. We use the luminosity function, along with maps describing the redshift completeness of the current 2dFGRS catalogue...

The species description process of North and Central American Geotrupinae (Coleoptera: Scarabaeoidea: Geotrupidae)

Trotta-Moreu,Nuria; Cabrero-Sañudo,Francisco José
Fonte: Instituto de Biología Publicador: Instituto de Biología
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2010 Português
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The description process for North and Central American species of Geotrupinae was analyzed and compared with that of Western Palaearctic species. This process was fitted to an asymptotic function to explore when the curve stabilized. By means of GLMs, the influence of some variables from 3 different groups (body size, geographic range and location) was examined, taking into account both pure and combined effects on the development of the process of species description. The accumulation curve of North and Central American Geotrupinae showed that probably 84-91% of the total number of species is already known and 10-20 species remain yet to be described. Body size has not shown any influence on Geotrupinae species description for either region. The most influential elements were the pure effect of the geographic range, followed by the pure effect of the geographic location, and their combined effect. These same variables were also the most influential in the Western Palaearctic region, although with a different significance. As this species inventory remains yet to be completed, it is possible that some factors, such as distribution, could become progressively more important, as for the Geotrupinae species in the Western Palaearctic region.