Combining exclusive semi-leptonic and hadronic B decays to measure |V_ub|

The Cabibbo-Kobayashi-Maskawa matrix element |V_ub| can be extracted from the rate for the semi-leptonic decay B -> pi + l + antineutrino_l, with little theoretical uncertainty, provided the hadronic form factor for the B -> pi transition can be measured from some other B decay. In here, we suggest using the decay B -> pi J\psi. This is a color suppressed decay, and it cannot be properly described within the usual factorization approximation; we use instead a simple and very general phenomenological model for the b d J\psi vertex. In order to relate the hadronic form factors in the B -> pi J\psi and B -> pi + l + antineutrino_l decays, we use form factor relations that hold for heavy-to-light transitions at large recoil.Comment: Latex, 7 pages, no figure

The Mass-to-Light Ratio of Binary Galaxies

We report on the mass-to-light ratio determination based on a newly selected binary galaxy sample, which includes a large number of pairs whose separations exceed a few hundred kpc. The probability distributions of the projected separation and the velocity difference have been calculated considering the contamination of optical pairs, and the mass-to-light ratio has been determined based on the maximum likelihood method. The best estimate of $M/L$ in the B band for 57 pairs is found to be 28 $\sim$ 36 depending on the orbital parameters and the distribution of optical pairs (solar unit, $H_0=50$ km s$^{-1}$ Mpc$^{-1}$). The best estimate of $M/L$ for 30 pure spiral pairs is found to be 12 $\sim$ 16. These results are relatively smaller than those obtained in previous studies, but consistent with each other within the errors. Although the number of pairs with large separation is significantly increased compared to previous samples, $M/L$ does not show any tendency of increase, but found to be almost independent of the separation of pairs beyond 100 kpc. The constancy of $M/L$ beyond 100 kpc may indicate that the typical halo size of spiral galaxies is less than $\sim 100$ kpc.Comment: 18 pages + 8 figures, to appear in ApJ Vol. 516 (May 10

Group Theory analysis of phonons in two-dimensional Transition Metal Dichalcogenides

Transition metal dichalcogenides (TMDCs) have emerged as a new two dimensional materials field since the monolayer and few-layer limits show different properties when compared to each other and to their respective bulk materials. For example, in some cases when the bulk material is exfoliated down to a monolayer, an indirect-to-direct band gap in the visible range is observed. The number of layers $N$ ($N$ even or odd) drives changes in space group symmetry that are reflected in the optical properties. The understanding of the space group symmetry as a function of the number of layers is therefore important for the correct interpretation of the experimental data. Here we present a thorough group theory study of the symmetry aspects relevant to optical and spectroscopic analysis, for the most common polytypes of TMDCs, i.e. $2Ha$, $2Hc$ and $1T$, as a function of the number of layers. Real space symmetries, the group of the wave vectors, the relevance of inversion symmetry, irreducible representations of the vibrational modes, optical selection rules and Raman tensors are discussed.Comment: 32 pages, 4 figure

Detrended Fluctuation Analysis of Systolic Blood Pressure Control Loop

We use detrended fluctuation analysis (DFA) to study the dynamics of blood pressure oscillations and its feedback control in rats by analyzing systolic pressure time series before and after a surgical procedure that interrupts its control loop. We found, for each situation, a crossover between two scaling regions characterized by exponents that reflect the nature of the feedback control and its range of operation. In addition, we found evidences of adaptation in the dynamics of blood pressure regulation a few days after surgical disruption of its main feedback circuit. Based on the paradigm of antagonistic, bipartite (vagal and sympathetic) action of the central nerve system, we propose a simple model for pressure homeostasis as the balance between two nonlinear opposing forces, successfully reproducing the crossover observed in the DFA of actual pressure signals

Balanço iônico em dietas para ruminantes na prevenção da febre do leite.

Equações de BCAD e importância de alguns íons; Suplementação da dieta com sais aniônicos; Emprego do balanço cátion-aniônico: efeito na prevenção da febre do leite; BCAD e produção de leite; BCAD e aceitabilidade da dieta; BCAD e estresse térmico.bitstream/item/81985/1/Balanco-ionico-em-dietas.pd

Efeito de fungicidas para controle de mofo branco em sementes de feijão para o controle de Sclerotinia sclerotiorum.

O objetivo deste trabalho foi avaliar diferentes fungicidas utilizados no tratamento de sementes, para controle de S. sclerotiorum em sementes de feijão comum

Aderência à legislação brasileira de produção orgânica: o caso dos produtores do Assentamento Chapadinha - DF.

Resumo A pesquisa teve como objetivo determinar o grau de aderência dos produtores familiares do Assentamento Chapadinha às leis e normas da produção orgânica vigentes no Brasil. Foram realizadas entrevistas abertas semiestruturadas para avaliação da percepção e conhecimento dos produtores sobre as normas mais importantes para a produção orgânica no Brasil: Lei 10.831/2003; Decreto 6.323/2007 e a IN 64/2008. As normas foram integradas em três unidades de análise: diretrizes dos sistemas e produção, processo de comercialização e métodos de certificação. Verificou-se que a documentação e registro constituem nos maiores entraves no processo de certificação de pequenos produtores. Em relação ao processo de comercialização e métodos de certificação verificou-se que os produtores apresentaram um grau de conhecimento mediano e aplicam alguns dos parâmetros preconizados na legislação, na comercialização e certificação. Abstract: This article aims to determine the adherence of Chapadinha?s organic small farmers to the production rules established in Brazil. The research methodology used was composed of open and semi-structured interviews, that intended to assess the perceptions and knowledge of growers on the most important regulations for organic production in Brazil: Law 10.831/2003; 6.323/2007 Decree, and IN 64/2008. The rules have been integrated into three units of analysis: guidelines and production systems, marketing process and certification methods. The work showed that the documentation constitutes the biggest obstacle in the process of certification of small farmers. Considering commercialization and certification it was observed that producers showed certain knowledge and apply some of the parameters of regulations related to the last two aspects mentioned