Combination of the top-quark mass measurements from the Tevatron collider

The top quark is the heaviest known elementary particle, with a mass about 40 times larger than the mass of its isospin partner, the bottom quark. It decays almost 100% of the time to a W boson and a bottom quark. Using top-antitop pairs at the Tevatron proton-antiproton collider, the CDF and D0 Collaborations have measured the top quark's mass in different final states for integrated luminosities of up to 5.8fb -1. This paper reports on a combination of these measurements that results in a more precise value of the mass than any individual decay channel can provide. It describes the treatment of the systematic uncertainties and their correlations. The mass value determined is 173.18±0.56(stat)±0.75(syst)GeV or 173.18±0.94GeV, which has a precision of ±0.54%, making this the most precise determination of the top-quark mass. © 2012 American Physical Society.

One-dimensional Fermi accelerator model with moving wall described by a nonlinear van der Pol oscillator

A modification of the one-dimensional Fermi accelerator model is considered in this work. The dynamics of a classical particle of mass m, confined to bounce elastically between two rigid walls where one is described by a nonlinear van der Pol type oscillator while the other one is fixed, working as a reinjection mechanism of the particle for a next collision, is carefully made by the use of a two-dimensional nonlinear mapping. Two cases are considered: (i) the situation where the particle has mass negligible as compared to the mass of the moving wall and does not affect the motion of it; and (ii) the case where collisions of the particle do affect the movement of the moving wall. For case (i) the phase space is of mixed type leading us to observe a scaling of the average velocity as a function of the parameter (χ) controlling the nonlinearity of the moving wall. For large χ, a diffusion on the velocity is observed leading to the conclusion that Fermi acceleration is taking place. On the other hand, for case (ii), the motion of the moving wall is affected by collisions with the particle. However, due to the properties of the van der Pol oscillator, the moving wall relaxes again to a limit cycle. Such kind of motion absorbs part of the energy of the particle leading to a suppression of the unlimited energy gain as observed in case (i). The phase space shows a set of attractors of different periods whose basin of attraction has a complicated organization. © 2013 American Physical Society.

Biological notes on the parasitism of apoica flavissima Van der Vecht (Hymenoptera: Vespidae) by Seminota marginata (Westwood) (Hymenoptera: Trigonalidae): Are social paper wasps primary or secundary hosts of trigonalidae?

Hosts of Trigonalidae include larvae of social paper wasps, which have been considered secondary hosts, supposedly following predation of the primary host (usually caterpillars) by adult wasps. This study provides observations on biological aspects of the parasitism of Apoica flavissima Van der Vecht by Seminota marginata (Westwood), and suggests that social wasps may be both primary and secondary hosts, whereas they extract and chew vegetable fiber.

Chile: ¿hacia dónde van los partidos?

Incluye Bibliografía

As relações entre a Matemática e a Astronomia no século XVI: tradução e comentários da obra Ouranographia de Adriaan van Roomen

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ciclos limites e a equação de van der Pol

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ensino e aprendizagem de poliedros regulares via a teoria de Van Hiele com origami

Pós-graduação em Matemática em Rede Nacional - IBILCE

Fragmento e montagem em Mauricio Kagel: uma análise de Ludwig Van

Pós-graduação em Música - IA

Neotomismo e educação em Leonardo Van Acker: uma aproximação entre católicos e escolanovistas nos anos 30

Pós-graduação em Educação - FFC

Identificação e análise das áreas domicilares do boto-cinza, Sotalia guianensis (Van Bénéden, 1864), no estuário de Cananéia, São Paulo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aplicações da equação de Van Der Waals no estudo de colisões entre átomos e moléculas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The collections of Lauraceae in the Herbarium of Henri Van Heurck (AWH)

Background and aims - The collections of Lauraceae in the Van Heurck Herbarium (AWH), which is currently on permanent loan to BR, have remained unknown by most of the specialists and by the general public up until the present. The taxonomic status of its one hundred and forty nine specimens of Lauraceae is here presented.Methods - Standard herbarium taxonomy practices were used in conjunction with the literature available. Specimens from fifty eight different herbaria were studied personally, or by checking their holdings available in the internet, or from digital images received from the curators.Key results - The specimens of Lauraceae from AWH are distributed in twenty four genera and seventy eight species with taxonomic status resolved, excepting for three specimens pertaining to species name of status uncertain (one), or to unresolved determination (two). From them, fifty three specimens are nomenclatural types of any sort, which corroborate the relevance of exsiccates acquired by Van Heurck, even for this relatively small set of specimens for the family. Fifteen lectotypifications and one neotypification of species names are proposed here.

Arte e resistência: Vincent Willem Van Gogh

Esta tese apresenta uma proposta interdisciplinar para abordar o objeto artístico, almejando demonstrar como a Psicologia pode enfocar a leitura e a interpretação das produções artísticas visuais. Foram aplicados métodos psicológicos considerados eficazes para entender o fenômeno artístico e, assim, interpretar o trabalho do artista. O instrumental teórico foi o da apreensão fenomenológica e o conhecimento psicanalítoco. Trinta e nove telas de Van Gogh (produzidas em Arles, 1888; no asilo de Saint Rémy, Provence, 1889; e em Auvers Sur Oise, 1890) foram selecionadas para análise. Foram Observados os aspectos da visualidade da obra, segundo a ótica fenomenológica, e as imagens foram investigadas em sua disposição em um espaço simbólico do espaço pessoal do artista, dos elementos configurados que compõem a foma, da iluminação e cor empregadas no trabalho e da dinâmica e expressão dos conteúdos manifestos. A tese constitui-se de quatro capítulos. O primeiro apresenta a história do artista; o segundo, a teoria para abordar a percepção fenomenológica, definindo elementos utilizados para interpretar o objeto artístico; o terceiro analisa as imagens produzidas por Van Gogh no período estudado; o quarto diagnostica, analisa e interpreta a expressão das imagens. Foi também analisada a temática explorada pelo artista, de acordo com sua manifestação simbólica. A trajetória deste trabalho assemelhase ao psicodiagnóstico, que levanta hipóteses e verifica se elas são verdadeiras ou falsas. Assim foi levantada a hipótese de que a arte atuava na existência do artista como um procedimento terapêutico e mantenedor do seu equilibrio. A maior êncase da literatura recai na loucura de Van Gogh como propulsora de sua obra, visão oposta à desta tese... (Resumo completo, clicar acesso eletrônico abaixo)

Benefits of soil carbon: report on the outcomes of an international scientific committee on problems of the environment rapid assessment workshop

A Scientific Committee on Problems of the Environment Rapid Assessment (SCOPE-RAP) workshop was held on 18-22 March 2013. This workshop was hosted by the European Commission, JRC Centre at Ispra, Italy, and brought together 40 leading experts from Africa, Asia, Europe and North and South America to create four synthesis chapters aimed at identifying knowledge gaps, research requirements, and policy innovations. Given the forthcoming publication by CABI of a book volume of the outcomes of the SCOPE-RAP in 2014, this workshop report provides an update on the global societal challenge of soil carbon management and some of the main issues and solutions that were identified in the four working sessions.