Using torsion to manipulate spin currents

We address the problem of quantum particles moving on a manifold characterised by the presence of torsion along a preferential axis. In fact, such a torsion may be taylored by the presence of a single screw dislocation, whose Burgers vector measures the torsion amplitude. The problem, first treated in the relativistic limit describing fermions that couple minimally to torsion, is then analysed in the Pauli limit We show that torsion induces a geometric potential and also that it couples generically to the phase of the wave function, giving rise to the possibility of using torsion to manipulate spin currents in the case of spinor wave functions. These results emerge as an alternative strategy for using screw dislocations in the design of spintronic-based devices

XMM-Newton EPIC and OM observation of Nova Centauri 1986 (V842 Cen)

We report the results from the temporal and spectral analysis of an XMM-Newton observation of Nova Centauri 1986 (V842 Cen). We detect a period at 3.51$\pm$0.4 h in the EPIC data and at 4.0$\pm$0.8 h in the OM data. The X-ray spectrum is consistent with the emission from an absorbed thin thermal plasma with a temperature distribution given by an isobaric cooling flow. The maximum temperature of the cooling flow model is $kT_{max}=43_{-12}^{+23}$ keV. Such a high temperature can be reached in a shocked region and, given the periodicity detected, most likely arises in a magnetically-channelled accretion flow characteristic of intermediate polars. The pulsed fraction of the 3.51 h modulation decreases with energy as observed in the X-ray light curves of magnetic CVs, possibly due either to occultation of the accretion column by the white dwarf body or phase-dependent to absorption. We do not find the 57 s white dwarf spin period, with a pulse amplitude of 4 mmag, reported by Woudt et al. (2009) either in the Optical Monitor (OM) data, which are sensitive to pulse amplitudes $\gtrsim$ 0.03 magnitudes, or the EPIC data, sensitive to pulse fractions $p \gtrsim$ 14 $\pm$2%.Comment: 5 pages, 3 figures; MNRAS, accepte

Building Socially Responsive Curricula through Emancipatory Action Research: International Contexts

"Two educators – one in USA and the other in Brazil – explore the possibilities and challenges for building socially responsive curricula through emancipatory action research. Habermas’ works on Theory of Communicative Action and Knowledge and Human Interests provide the theoretical framework for understanding curriculum and educational research. Explorations of the impact of local and national policies on the authors’ professional practices and research activities allowed them to compare the possibilities and challenges (in each country) for building socially responsive curricula. Right now, Brazil shows greater possibilities than the US, despite its limited material resources and personnel prepared to take advantage of those possibilities. In the US, the takeover of the education system by the corporatocracy with its market fundamentalism and assault to democracy has become a major obstacle for building socially responsive curricula in schools. The teacher / action research movement, though still marginal, is helping to counteract this trend." (author's abstract

Shotgun Mitogenomics Provides a Reference Phylogenetic Framework and Timescale for Living Xenarthrans

Xenarthra (armadillos, sloths, and anteaters) constitutes one of the four major clades of placental mammals. Despite their phylogenetic distinctiveness in mammals, a reference phylogeny is still lacking for the 31 described species. Here we used Illumina shotgun sequencing to assemble 33 new complete mitochondrial genomes, establishing Xenarthra as the first major placental clade to be fully sequenced at the species level for mitogenomes. The resulting data set allowed the reconstruction of a robust phylogenetic framework and timescale that are consistent with previous studies conducted at the genus level using nuclear genes. Incorporating the full species diversity of extant xenarthrans points to a number of inconsistencies in xenarthran systematics and species definition. We propose to split armadillos in two distinct families Dasypodidae (dasypodines) and Chlamyphoridae (euphractines, chlamyphorines, and tolypeutines) to better reflect their ancient divergence, estimated around 42 million years ago. Species delimitation within long-nosed armadillos (genus Dasypus) appeared more complex than anticipated, with the discovery of a divergent lineage in French Guiana. Diversification analyses showed Xenarthra to be an ancient clade with a constant diversification rate through time with a species turnover driven by high but constant extinction. We also detected a significant negative correlation between speciation rate and past temperature fluctuations with an increase in speciation rate corresponding to the general cooling observed during the last 15 million years. Biogeographic reconstructions identified the tropical rainforest biome of Amazonia and the Guianan shield as the cradle of xenarthran evolutionary history with subsequent dispersions into more open and dry habitats.Fil: Gibb, Gillian C.. Universite de Montpellier; Francia. Massey Universit; Nueva ZelandaFil: Condamine, Fabien L.. University of Gothenburg; Suecia. Universite de Montpellier; Francia. University of Alberta; CanadáFil: Kuch, Melanie. McMaster University; CanadáFil: Enk, Jacob. McMaster University; CanadáFil: Moraes Barros, Nadia. Universidade Do Porto; Portugal. Universidade de Sao Paulo; BrasilFil: Superina, Mariella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Poinar, Hendrik N.. McMaster University; CanadáFil: Delsuc, Frederic. Universite de Montpellier; Franci

A first appraisal of the landing and mechanism of the Santos fishery

This paper summarizes and analyses the landing data collected at Santos, Brazil, during the 12 months period, July 1958-June 1959. These data are given in terms of weight landed of the more important fish and shrimp and also in terms of value. The distribution of the landings of each of the more important species is shown both according to the type of fishing gear used and fishing area. The fishing area is given in the form of statistical rectangles of 60 miles square. The landings are broken down to obtain a figure for the landing per hour of fishing for each species, for each gear and for each rectangle fished. This figure of landing per unit fishing time is used to compare one area with another, one gear with another, and one month with another for each of the important species. In this way, comparisons of the available density of a species by time, area and fishing gear are made.Êste trabalho sintetiza e analisa os dados coletados em Santos, Brasil, sobre o desembarque de pescado durante o período de 12 meses, de julho de 1958 a junho de 1959. Estes dados são apresentados em termos de peso desembarcado, para as espécies de peixes mais importantes e camarões e, também, em termos de valor econômico. A distribuição dos desembarques de cada uma das espécies mais importantes é apresentada tanto em relação ao tipo de aparelho de pesca usado, como em relação à área de pesca. Essa área é dada sob forma de retângulos estatísticos de 60 milhas quadradas. Os desembarques são classificados para se obter o valor do desembarque por hora de pesca para cada espécie, para cada aparelho e para cada retângulo pescado. Este valor do desembarque por unidade de tempo de captura é usado para comparar as áreas entre si, os aparelhos de captura entre si e os meses do ano entre si, em relação a cada espécie importante. Deste modo são feitas as comparações da densidade disponível de uma espécie no tempo, na área de pesca e por aparelho de pesca

Utilização de bioestimulantes na cultura da cana-de-açúcar (Saccharum officinarum L.).

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