Plasma and testicular testosterone levels, volume density and number of Leydig cells and spermatogenic efficiency of rabbits

Plasma and tissue testosterone concentrations were determined by radioimmunoassay in 12 eight-month-old sexually mature New Zealand White rabbits and evaluated for possible associations with spermatogenic efficiency as well as with volume density and number of Leydig cells. Testicular tissue was processed histologically and histometry was performed in order to quantify germ cells, Sertoli cells and Leydig cells. Spermatogenic efficiency, reported as the ratios among germ cells (spermatogonia, primary spermatocytes and round spermatids) and by the ratio of germ cells to Sertoli cells, was not associated with testosterone levels. However, Leydig cell parameters such as number of Leydig cells per gram of testis, total number of Leydig cells per testis and percent cell volume of Leydig cell nuclei were correlated significantly with testosterone levels. The statistically significant correlation (r = 0.82, P\u3c0.05) observed between testosterone levels and the number of Leydig cells per gram of testis suggests that, in the rabbit, the latter parameter can serve as a criterion for monitoring testosterone levels in this species under normal conditions

A necrópole tardo-romana e medieval de Talaíde (Cascais) : caracterização e integração cultural: análises não destrutivas do espólio metálico

International audienc

Localization properties of a tight-binding electronic model on the Apollonian network

An investigation on the properties of electronic states of a tight-binding Hamiltonian on the Apollonian network is presented. This structure, which is defined based on the Apollonian packing problem, has been explored both as a complex network, and as a substrate, on the top of which physical models can defined. The Schrodinger equation of the model, which includes only nearest neighbor interactions, is written in a matrix formulation. In the uniform case, the resulting Hamiltonian is proportional to the adjacency matrix of the Apollonian network. The characterization of the electronic eigenstates is based on the properties of the spectrum, which is characterized by a very large degeneracy. The $2\pi /3$ rotation symmetry of the network and large number of equivalent sites are reflected in all eigenstates, which are classified according to their parity. Extended and localized states are identified by evaluating the participation rate. Results for other two non-uniform models on the Apollonian network are also presented. In one case, interaction is considered to be dependent of the node degree, while in the other one, random on-site energies are considered.Comment: 7pages, 7 figure

The pros and cons of using SDL for creation of distributed services

In a competitive market for the creation of complex distributed services, time to market, development cost, maintenance and flexibility are key issues. Optimizing the development process is very much a matter of optimizing the technologies used during service creation. This paper reports on the experience gained in the Service Creation projects SCREEN and TOSCA on use of the language SDL for efficient service creation

Electromagnetic radiation from collisions at almost the speed of light: an extremely relativistic charged particle falling into a Schwarzschild black hole

We investigate the electromagnetic radiation released during the high energy collision of a charged point particle with a four-dimensional Schwarzschild black hole. We show that the spectra is flat, and well described by a classical calculation. We also compare the total electromagnetic and gravitational energies emitted, and find that the former is supressed in relation to the latter for very high energies. These results could apply to the astrophysical world in the case charged stars and small charged black holes are out there colliding into large black holes, and to a very high energy collision experiment in a four-dimensional world. In this latter scenario the calculation is to be used for the moments just after the black hole formation, when the collision of charged debris with the newly formed black hole is certainly expected. Since the calculation is four-dimensional, it does not directly apply to Tev-scale gravity black holes, as these inhabit a world of six to eleven dimensions, although our results should qualitatively hold when extrapolated with some care to higher dimensions.Comment: 6 pages, 2 figure

Extreme vortex pinning in the non-centrosymmetric superconductor CePt3_{3}Si

We report on the vortex dynamics of a single crystal of the non-centrosymmetric heavy-fermion superconductor CePt$_{3}$Si. Decays of the remnant magnetization display a clean logarithmic time dependence with rates that follow the temperature dependence expected from the Kim-Anderson theory. The creep rates are lower than observed in any other centrosymmetric superconductor and are not caused by high critical currents. On the contrary, the critical current in CePt$_{3}$Si is considerably lower than in other superconductors with strong vortex pinning indicating that an alternative impediment on the flux line motion might be at work in this superconductor.Comment: 4 pages, 5 figure

Estudo da interação genótipo-ambiente para a característica peso ao sobreano de bovinos da raça Canchim.

O objetivo deste trabalho foi estudar a presença de interação genótipo-ambiente (IGA) em bovinos Canchim, por meio de correlações genéticas, pela abordagem bayesiana e por um modelo animal, entre os pesos ao sobreano (PS) de 4 regiões distintas do Brasil. O modelo de análise estatística multicaracterística incluiu os efeitos de grupo de contemporâneos, idade do animal ao sobreano, como covariável, além dos efeitos genéticos aditivos diretos e residuais. As herdabilidades nas 4 regiões foram de baixas a moderadas magnitudes, no intervalo [0,21-0,29]. As correlações genéticas entre as 4 regiões variaram de baixa a moderada magnitude, sugerindo a presença da IGA. Os resultados evidenciaram que a expressão fenotípica do PS dependeu do ambiente em que foi medido e que os genótipos dos animais foram reordenados nas diferentes regiões.Resumos na seguinte fonte: Archivos Latinoamericano de Produccion Animal, v. 15, (Supl.1), p. 343, 2007

Doses de NPK, produção de massa seca e nutrição em feijão-de-metro.

Este trabalho objetivou estudar os teores de nutrientes na folha e a produção de massa seca da parte aérea do feijão-de-metro submetido a diferentes doses de NPK (4-14-8), em um solo representativo de terra firme, visando gerar subsídios úteis para seu manejo

Cartilha de educação ambiental da embrapa florestas: os seis gigantes do planeta.

EVINCI. Resumo 013