Structure and relaxations in liquid and amorphous Selenium

We report a molecular dynamics simulation of selenium, described by a three-body interaction. The temperatures T_g and T_c and the structural properties are in agreement with experiment. The mean nearest neighbor coordination number is 2.1. A small pre-peak at about 1 AA^-1 can be explained in terms of void correlations. In the intermediate self-scattering function, i.e. the density fluctuation correlation, classical behavior, alpha- and beta-regimes, is found. We also observe the plateau in the beta-regime below T_g. In a second step, we investigated the heterogeneous and/or homogeneous behavior of the relaxations. At both short and long times the relaxations are homogeneous (or weakly heterogeneous). In the intermediate time scale, lowering the temperature increases the heterogeneity. We connect these different domains to the vibrational (ballistic), beta- and alpha-regimes. We have also shown that the increase in heterogeneity can be understood in terms of relaxations

SKI-1 and Furin Generate Multiple RGMa Fragments that Regulate Axonal Growth

SummaryThe nervous system is enormously complex, yet the number of cues that control axonal growth is surprisingly meager. Posttranslational modifications amplify diversity, but the degree to which they are employed is unclear. Here, we show that Furin and SKI-1 combine with autocatalytic cleavage and a disulfide bridge to generate four membrane-bound and three soluble forms of the repulsive guidance molecule (RGMa). We provide in vivo evidence that these proprotein convertases are involved in axonal growth and that RGMa cleavage is essential for Neogenin-mediated outgrowth inhibition. Surprisingly, despite no sequence homology, N- and C-RGMa fragments bound the same Fibronectin-like domains in Neogenin and blocked outgrowth. This represents an example in which unrelated fragments from one molecule inhibit outgrowth through a single receptor domain. RGMa is a tethered membrane-bound molecule, and proteolytic processing amplifies RGMa diversity by creating soluble versions with long-range effects as well

Distâncias genéticas em equinos (Equus caballus) por meio de marcadores microssatélites.

A raça Marajoara é bastante difundida e utilizada nas fazendas da ilha de Marajó e está sendo mantida em conservação no Banco de Germoplasma Animal da Amazônia Oriental ? BAGAM, da Embrapa Amazônia Oriental, sendo altamente adaptada às condições climáticas e ao relevo que caracterizam essa região. Foram utilizadas amostras da raça Marajoara (54), Puruca (47),Mangalarga (30), Puro Sangue Inglês (47), Árabe (25), Pantaneiro (63) coletados no Brasil e Lusitano (93), Árabe (48), Asturcon (39), Pura Raça Espanhola (60), Puro Sangue Inglês (46), Losino(59), Mallorquina (30), Menorquina (69) e Potoka (27) coletados na Espanha. Foram utilizados 22iniciadores (HTG4, AHT4, HMS7, ASB2, ASB17, HMS6, ASB23, HTG10, HMS3, LEX33, T287, T294,T297, T301, T312, T321, T325, T333, T341, T394, T343 e T344) amplificados pelo método de Reação em Cadeia da Polimerase (PCR). Os produtos da PCR foram separados em gel desnaturante de poliacrilamida 6%. Foram detectados 236 alelos, com média igual a 7,5 alelos/locus, variando entre 16 e 6 alelos. As médias de Conteúdo de Informação Polimórfica (PIC) e as heterozigosidades observadas (Ho) e esperadas (He), conforme as raças estudadas, foram respectivamente, 0,7610, 0,7873 e 0,7413. A estimativa da estatística F de Wright (1978) mostrou que a variação entre as raças foi maior (Fst 8,1%) do que dentro delas (Fis 0,78%), demonstrando que a diferenciação genética neste estudo foi maior entre as raças do que dentro de cada uma delas. Foram observados poucos desvios em relação ao equilíbrio de Hardy ? Weinberg. A menor distância genética observada foi entre a raça Marajoara e a Puruca seguida da Mangalarga. Os resultados sugerem que a raça Marajoara representa um grupo genético claramente distinto deoutras raças excetuando-se a Puruca que pode ser utilizada como reservatório de genes para esta, com razoável variabilidade genética. Medidas de conservação e manejo devem ser intensificadas nesse importante recurso genético brasileiro a fim de evitar a sua descaracterização e perda de identidade genética

Computing the first eigenpair of the p-Laplacian via inverse iteration of sublinear supersolutions

We introduce an iterative method for computing the first eigenpair $(\lambda_{p},e_{p})$ for the $p$-Laplacian operator with homogeneous Dirichlet data as the limit of $(\mu_{q,}u_{q})$ as $q\rightarrow p^{-}$, where $u_{q}$ is the positive solution of the sublinear Lane-Emden equation $-\Delta_{p}u_{q}=\mu_{q}u_{q}^{q-1}$ with same boundary data. The method is shown to work for any smooth, bounded domain. Solutions to the Lane-Emden problem are obtained through inverse iteration of a super-solution which is derived from the solution to the torsional creep problem. Convergence of $u_{q}$ to $e_{p}$ is in the $C^{1}$-norm and the rate of convergence of $\mu_{q}$ to $\lambda_{p}$ is at least $O(p-q)$. Numerical evidence is presented.Comment: Section 5 was rewritten. Jed Brown was added as autho