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)

Aspectos biológicos de Quesada gigas (Olivier, 1790) (Hemiptera: Cicadidae) em cafeeiro

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

Distribuição espacial de Quesada gigas (Oliver, 1790) (Hemiptera: Cicadidae) na cultura do café

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

O Conselho de Estado e o princípio da divisão de poderes (1828-1834)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Os socorros públicos no Império do Brasil 1822 a 1834

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

Revisão taxonômica do gênero Mustelus Link, 1790 do Brasil (Chondrichthyes, Carcharhiniformes, Triakidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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)