On Useful Conformal Tranformations In General Relativity

Local conformal transformations are known as a useful tool in various applications of the gravitational theory, especially in cosmology. We describe some new aspects of these transformations, in particular using them for derivation of Einstein equations for the cosmological and Schwarzschild metrics. Furthermore, the conformal transformation is applied for the dimensional reduction of the Gauss-Bonnet topological invariant in $d=4$ to the spaces of lower dimensions.Comment: 17 pages, LaTeX. The paper is intended mainly for pedagogical purposes and represents a collection of exercises concerning local conformal transformations and dimensional reduction. To be published in "Gravitation and Cosmology

Effect size and statistical power in the rodent fear conditioning literature - A systematic review

<div><p>Proposals to increase research reproducibility frequently call for focusing on effect sizes instead of p values, as well as for increasing the statistical power of experiments. However, it is unclear to what extent these two concepts are indeed taken into account in basic biomedical science. To study this in a real-case scenario, we performed a systematic review of effect sizes and statistical power in studies on learning of rodent fear conditioning, a widely used behavioral task to evaluate memory. Our search criteria yielded 410 experiments comparing control and treated groups in 122 articles. Interventions had a mean effect size of 29.5%, and amnesia caused by memory-impairing interventions was nearly always partial. Mean statistical power to detect the average effect size observed in well-powered experiments with significant differences (37.2%) was 65%, and was lower among studies with non-significant results. Only one article reported a sample size calculation, and our estimated sample size to achieve 80% power considering typical effect sizes and variances (15 animals per group) was reached in only 12.2% of experiments. Actual effect sizes correlated with effect size inferences made by readers on the basis of textual descriptions of results only when findings were non-significant, and neither effect size nor power correlated with study quality indicators, number of citations or impact factor of the publishing journal. In summary, effect sizes and statistical power have a wide distribution in the rodent fear conditioning literature, but do not seem to have a large influence on how results are described or cited. Failure to take these concepts into consideration might limit attempts to improve reproducibility in this field of science.</p></div

Failure mechanisms and surface roughness statistics of fractured Fontainebleau sandstone

In an effort to investigate the link between failure mechanisms and the geometry of fractures of compacted grains materials, a detailed statistical analysis of the surfaces of fractured Fontainebleau sandstones has been achieved. The roughness of samples of different widths W is shown to be self affine with an exponent zeta=0.46 +- 0.05 over a range of length scales ranging from the grain size d up to an upper cut-off length \xi = 0.15 W. This low zeta value is in agreement with measurements on other sandstones and on sintered materials. The probability distributions P(delta z,delta h) of the variations of height over different distances delta z > d can be collapsed onto a single Gaussian distribution with a suitable normalisation and do not display multifractal features. The roughness amplitude, as characterized by the height-height correlation over fixed distances delta z, does not depend on the sample width, implying that no anomalous scaling of the type reported for other materials is present. It is suggested, in agreement with recent theoretical work, to explain these results by the occurence of brittle fracture (instead of damage failure in materials displaying a higher value of zeta = 0.8).Comment: 7 page

Efeitos do ambiente sobre o peso a desmama de bezerros Nelore nos municípios de Rio Branco e Boca do Acre.

O objetivo deste trabalho foi analisar os efeitos de ambiente sobre o peso ao desmame de bezerros Nelore, nascidos em três fazendas no Estado do Acre, nos anos de 2007 e 2008. Avaliaram-se os efeitos de sexo, fazenda, ano e mês de nascimento. A analise estatística foi realizada utilizando-se o método dos quadrados mínimos, procedimento GLM (SAS, 2000), com um modelo estatístico contendo como fonte de variação os efeitos fixos de sexo, fazenda, ano e mês de nascimento. Todas as fontes de variação do modelo foram significativas. A importância desses efeitos não genéticos sobre o peso a desmama, evidenciam a necessidade de se fazer ajustes para os mesmos, visando uma maior acurácia nos estudos referentes a avaliação genética, seleção e comparação entre pesos dos animais, visto que estes influenciam sobre a característica estudada

Pollen mixture, a recombination alternative in common bean breeding.

Recombination can be a limiting factor in recurrent selection programs, especially in species such as common bean where artificial hybridization reduces seed setting. Therefore, the development of new techniques to improve recombination efficiency is important. Experiments were conduted in two sowing periods, July (autumn-winter season) and February (dry growing season), using the ESAL 686 and Small White cultivars as the female parents and the Carioca, Ouro Negro and ESAL 686 or Small While cutivars as male parents, depending ot the female parent. Five technicians with different hybridization experience and two hybridization methods (with and without emasculation) were tested. A mixture of pollen from the three male parents was used in the pollinations, which were made in greenhouse. The resulting F1 seeds were sown in the field and the male parent identified by morphological markers. The greatest pollination success (68%) occurred in the autumn-winter season without emasculation. It was also observed that the technicians differed in efficiency, but no method x technician interaction was detected. The pollen mixture was efficient to improve recombination

Densidade e volume total de poros do solo cultivado com adubos verdes perenes consorciados com a bananeira em um sistema sob transição agroecológica em Mato Grosso do Sul.

bitstream/item/68859/1/041-carneiro-densidade.pdfPublicado também no Cadernos de Agroecologia, v. 7, n.2, 2012

Macro e microporosidade do solo cultivado com adubos verdes perenes consorciados com a bananeira em um sistema sob transição agroecológica em Mato Grosso do Sul.

bitstream/item/69053/1/066-carneiro-macro.pdfPublicado também no Cadernos de Agroecologia, v. 7, n.2, 2012