Pion condensation in a dense neutrino gas

We argue that using an equilibrated gas of neutrinos it is possible to probe the phase diagram of QCD for finite isospin and small baryon chemical potentials. We discuss this region of the phase diagram in detail and demonstrate that for large enough neutrino densities a Bose-Einstein condensate of positively charged pions arises. Moreover, we show that for nonzero neutrino density the degeneracy in the lifetimes and masses of the charged pions is lifted.Comment: 10 pages, 7 figures. Modifications to Section II, IIIc, and I

The Superspace of Geometrodynamics

Wheeler's Superspace is the arena in which Geometrodynamics takes place. I review some aspects of its geometrical and topological structure that Wheeler urged us to take seriously in the context of canonical quantum gravity.Comment: 29 pages, 8 figures. To appear in the Wheeler memorial volume of General Relativity and Gravitatio

Orca Reduction and ContrAction Graph Clustering

During the last years, a wide range of huge networks has been made available to researchers. The discovery of natural groups, a task called graph clustering, in such datasets is a challenge arising in many applications such as the analysis of neural, social, and communication networks. We here present Orca, a new graph clustering algorithm, which operates locally and hierarchically contracts the input. In contrast to most existing graph clustering algorithms, which operate globally, Orca is able to cluster inputs with hundreds of millions of edges in less than 2.5 hours, identifying clusterings with measurably high quality. Our approach explicitly avoids maximizing any single index value such as modularity, but instead relies on simple and sound structural operations. We present and discuss the Orca algorithm and evaluate its performance with respect to both clustering quality and running time, compared to other graph clustering algorithms

Parâmetros genéticos para escore de umbigo e características de produção em bovinos da raça Nelore Genetics parameters for umbilicus score and production characteristics in Nellore breed beef cattle

Utilizaram-se 11.310 medidas de escore visual da característica umbigo, medida aos 18 meses em bovinos, para estimar os componentes de variância, a herdabilidade e as correlações genéticas entre escore do umbigo e peso à desmama (PD) e ganho de peso da desmama ao sobreano (GP345), utilizando-se modelo animal bi-característica Os escores de umbigo (EU) variaram de 1 (mais pendulosos) a 5 (mais curtos). Os valores de herdabilidade foram 0,31 (PD), 0,14 (GP345) e 0,29 (EU), e as correlações genéticas foram -0,05 (EU×PD) e 0,14 (EU×GP345). A correlação entre avaliação do umbigo de machos e fêmeas foi de 0,80. Conclui-se que a característica umbigo é passível de seleção e que ela não compromete a seleção para melhores PD e GP345.<br>In this study 11,310 visual score measurements of navel characteristic, collected from bovines, were used. Visual scores for navel (NS), ranged from 1 (the longest) to 5 (the shortest). Variance components, genetic parameters and genetic correlations between navel characteristic of 18-month old animals and growth characteristics (weaning weight -WW and weight gain from weaning to over year -WG345) were estimated using a two-traits animal model. Heritability estimates were 0.31 (NS) abd 0.14 (WG345), and the genetic correlation estimates were: -0.05 (NS×WW) and 0.14 (WW×WG345) and the estimated correlation between navel (female) ´ navel (male) was 0.80. Score navel can be object of selection and selection for shorter navel does not apparently significantly affect animal performance for WW and WG345