The hydrostatic equilibrium and Tsallis equilibrium for self-gravitating systems

Self-gravitating systems are generally thought to behavior non-extensively due to the long-range nature of gravitational forces. We obtain a relation between the nonextensive parameter q of Tsallis statistics, the temperature gradient and the gravitational potential based on the equation of hydrostatic equilibrium of self-gravitating systems. It is suggested that the nonextensive parameter in Tsallis statistics has a clear physical meaning with regard to the non-isothermal nature of the systems with long-range interactions and Tsallis equilibrium distribution for the self-gravitating systems describes the property of hydrostatic equilibrium of the systems.Comment: 7 pages, 9 Reference

Scaffolds of calcium phosphate cement containing chitosan and gelatin

Calcium phosphate cements (CPCs) have potential to be used on repairing damaged bones due to their moldability, bioactivity and bioresorbability. These materials combine calcium orthophosphate powders with a liquid leading to a paste that hardens spontaneously at low temperatures. Hence, CPCs could be applied as scaffolds to support cell/tissue growth. This paper studies CPC scaffolds processing by foaming cement's liquid phase in which was added gelatin and chitosan. The former acted to increase the foam stability while the ladder acted as a foaming agent. Moreover, these polymers would enhance scaffold's biological properties by controlling material's total porosity and in vivo resorption. The method proposed led to scaffolds with 58.71% porosity with sizes ranging from 160 to 760 µm and compressive strength of 0.70MPa. After foaming, pores' size, distribution and interconnectivity changed significantly leading to a material that could be applied on bone regeneration since it would allow nutrient's transport, cell attachment and an increase in material degradation rate.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Federal University of São Paulo Institute of Science and Technology Bioceramics LaboratoryUniversity of Campinas Institute of Chemistry Physical Chemistry DepartmentUNIFESP, Institute of Science and Technology Bioceramics LaboratoryFAPESP: 2011/09240-9SciEL

Failure of sexing by developmental arrest of bovine embryos in vitro produced with H-Y antisera

Embriões bovinos produzidos in vitro, em estádio de mórula, foram cultivados em meio contendo anticorpos anti H-Y de alto título proveniente de ratos por 24h e, após este tempo, classificados em dois grupos: 1) embriões inibidos em estádio de mórula (classificados como machos) e 2) embriões que se desenvolveram e formaram a blastocele (classificados como fêmeas). O sexo de 311 embriões, distribuídos em três grupos de concentração dos anticorpos, 3%, 5% ou 7%, foi identificado pela reação em cadeia da polimerase. Não houve desvio da proporção entre machos e fêmeas (P>0,05) nos grupos em que se utilizaram os anticorpos anti H-Y, quando comparadas ao grupo-controle, sem adição de anticorpos anti H-Y. Diferentemente dos resultados obtidos utilizando-se embriões bovinos produzidos in vivo, a sexagem com anticorpos anti H-Y de alto título em embriões produzidos in vitro não propiciou sucesso.In vitro produced bovine embryos at morula stage were cultured in medium containing high titer of rat H-Y antisera for 24h. The embryos were classified in two groups: 1) embryos arrested at morula stage (classified as males); and 2) embryos that developed and formed a blastocoele (classified as female). The sex of 311 embryos, divided in three groups of concentration of H-Y antisera, 3%, 5% or 7%, was identified by polimerase chain reaction. The results showed no difference (P>0.05) on sexual deviation in groups in which the H-Y antisera was added, in relation to control group, in which no H-Y antisera was added. In contrast with results obtained with in vivo produced bovine embryos, the sexing of in vitro produced bovine embryos with high H-Y antisera titer did not succed.CNP

Environmental control on water vapour and energy exchanges over grasslands in semiarid region of Brazil

A micrometeorological experiment was conducted over grasslands in a semi-arid region of north-eastern Brazil (São João, Pernambuco) from January to December 2011, using the Bowen ratio energy balance method, to improve the current understanding of energy partitioning and water vapour exchange over this ecosystem in this region. The objectives of the present study were to quantify the seasonal and diurnal variations in energy and water vapour exchanges over grasslands and understand the biotic and abiotic factors controlling the energy partitioning of this ecosystem. In the dry period, the low stored soil water limited the grass production and leaf area index, and as a consequence of these conditions, most of the annual net radiation (58%) was consumed in sensible heat flux. During the course of the study the evaporative fraction was linearly related to the leaf area index. The total annual evapotranspiration and its daily maximum were 543.8 mm and 3.14 mm d-1. The seasonal and diurnal variations in energy partitioning and evapotranspiration were controlled by soil water availability and leaf area index

Transport in Coupled Quantum Dots: Kondo Effect Versus Anti-Ferromagnetic Correlation

The interplay between the Kondo effect and the inter-dot magnetic interaction in a coupled-dot system is studied. An exact result for the transport properties at zero temperature is obtained by diagonalizing a cluster, composed by the double-dot and its vicinity, which is connected to leads. It is shown that the system goes continuously from the Kondo regime to an anti-ferromagnetic state as the inter-dot interaction is increased. The conductance, the charge at the dots and the spin-spin correlation are obtained as a function of the gate potential.Comment: 4 pages, 3 postscript figures. Submitted to PR

Analysis of a spatial Lotka-Volterra model with a finite range predator-prey interaction

We perform an analysis of a recent spatial version of the classical Lotka-Volterra model, where a finite scale controls individuals' interaction. We study the behavior of the predator-prey dynamics in physical spaces higher than one, showing how spatial patterns can emerge for some values of the interaction range and of the diffusion parameter.Comment: 7 pages, 7 figure

Viabilidade de uso do híbrido Hawaii 7996 como porta-enxerto de cultuvares comerciais de tomate.

A técnica de enxertia é utilizada em algumas hortaliças, principalmente em áreas infestadas, para atribuir resistência a patógenos do solo, minimizando as perdas de produção de cultivares suscetíveis. Este trabalho teve como objetivo avaliar o desenvolvimento e a produtividade de plantas de tomateiro enxertadas em híbrido, tido como resistente a Ralstonia solanacearum, em comparação a pés-francos. O experimento foi desenvolvido em viveiro (produção de mudas e enxertia) e em céu aberto, no município de Cruz das Almas, Bahia, no período de outubro de 2003 a fevereiro de 2004. Utilizou-se o método de enxertia de fenda cheia, com o híbrido ‘Hawaii 7996’ como porta-enxerto e as cultivares Santa Clara, Santa Cruz Kada e Débora Plus, suscetíveis a R. solanacearum, como enxerto. O delineamento experimental foi em blocos ao acaso, com seis tratamentos (3 enxertados e 3 pés-francos), 5 repetições e 6 plantas por parcela útil. Avaliaram-se os caracteres: diâmetro do caule, altura da planta e da primeira inflorescência, distância entre inflorescências e produtividade comercial de frutos. O desenvolvimento das plantas, a produção total e a massa média dos frutos foram semelhantes para os tratamentos enxertados em relação a seus respectivos pés-francos e não houve incompatibilidade entre porta-enxerto e enxerto. A cultivar Santa Cruz Kada foi mais sensível às condições agroecológicas do município de Cruz das Almas, refletindo negativamente na produção e no peso médio dos frutos. Observou-se na enxertia com o híbrido ‘Hawaii 7996’ potencial para viabilizar a produção de tomateiros comerciais suscetíveis à murcha bacteriana, em áreas infestadas com R. solanacearum

Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization.

The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis)to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation.C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun