A new model for gravitational potential perturbations in disks of spiral galaxies. An application to our Galaxy

We propose a new, more realistic, description of the perturbed gravitational potential of spiral galaxies, with spiral arms having Gaussian-shaped groove profiles. We investigate the stable stellar orbits in galactic disks, using the new perturbed potential. The influence of the bulge mass on the stellar orbits in the inner regions of a disk is also investigated. The new description offers the advantage of easy control of the parameters of the Gaussian profile of its potential. We find a range of values for the perturbation amplitude from 400 to 800 km^2 s^{-2} kpc^{-1} which implies a maximum ratio of the tangential force to the axisymmetric force between 3% and 6%, approximately. Good self-consistency of arm shapes is obtained between the Inner Lindblad resonance (ILR) and the 4:1 resonance. Near the 4:1 resonance the response density starts to deviate from the imposed logarithmic spiral form. This creates bifurcations that appear as short arms. Therefore the deviation from a perfect logarithmic spiral in galaxies can be understood as a natural effect of the 4:1 resonance. Beyond the 4:1 resonance we find closed orbits which have similarities with the arms observed in our Galaxy. In regions near the center, in the presence of a massive bulge, elongated stellar orbits appear naturally, without imposing any bar-shaped potential, but only extending the spiral perturbation a little inward of the ILR. This suggests that a bar is formed with a half-size around 3 kpc by a mechanism similar to that of the spiral arms. The potential energy perturbation that we adopted represents an important step in the direction of self-consistency, compared to previous sine function descriptions of the potential. Our model produces a realistic description of the spiral structure, able to explain several details that were not yet understood.Comment: 12 pag., 11 fig. Accepted for publication in A&A, 2012 December 1

Management of von Willebrand disease type 3 during pregnancy - 2 cases reports.

BACKGROUND: von Willebrand disease type 3, is an extremely rare condition. It can be severe and potentially life-threatening, particularly in pregnant women during labor and subsequently during early puerperium. Due to its rarity, there is no optimal treatment/management during pregnancy. CASE: We describe two cases of pregnant women with von Willebrand disease type 3, and its successful surveillance and treatment with Haemate P FVIII (human plasma-derived von Willebrand Factor-ristocetin co-factor associated with human coagulation factor VIII), during pregnancy, partum and puerperium. CONCLUSIONS: Daily prophylaxis with Haemate P FVIII in women with von Willebrand disease type 3, starting 2 hours before caesarean section until the 7th day of puerperium, associated with close analytical and clinical surveillance seems to be a safe clinical option

Theoretical study of molecular electronic excitations and optical transitions of C60

We report results on ab initio calculations of excited states of the fullerene molecule by using configuration interaction (CI) approach with singly excited determinants (SCI). We have used both the experimental geometry and the one optimized by the density functional method and worked with basis sets at the cc-pVTZ and aug-cc-pVTZ level. Contrary to the early SCI semiempirical calculations, we find that two lowest $^1 T_{1u} \leftarrow {}^1 A_g$ electron optical lines are situated at relatively high energies of ~5.8 eV (214 nm) and ~6.3 eV (197 nm). These two lines originate from two $^1 T_{1u} \leftarrow {}^1 A_g$ transitions: from HOMO to (LUMO+1) ($6h_u \to 3t_{1g}$) and from (HOMO--1) to LUMO ($10h_g \to 7t_{1u}$). The lowest molecular excitation, which is the $1 ^3 T_{2g}$ level, is found at ~2.5 eV. Inclusion of doubly excited determinants (SDCI) leads only to minor corrections to this picture. We discuss possible assignment of absorption bands at energies smaller than 5.8 eV (or $\lambda$ larger than 214 nm).Comment: 6 pages, 1 figure, 9 Table

Avaliação do uso de fibra e mucilagem de curauá na produção de papel reciclado para embalagens.

O curauá (Ananas erectifolius L. B. Smith) é uma planta fibrosa da família das broméliceas cuja fibra pode ser utilizada na indústria automobilística, têxtil, farmacêutica, celulose e papel. O trabalho teve objetivo de avaliar o uso da fibra e mucilagem de curauá na produção de papel reciclado com a finalidade de produzir embalagens. O papel foi testado através das características aparência, textura e resistência no Núcleo de Responsabilidade Socioambiental da Embrapa Amazônia Oriental - NURES, localizado em Belém-PA. Os resultados preliminares mostraram que a associação de fibras e mucilagem de curauá com sobras e aparas de papel não compromete a aparência e textura do papel reciclado. O acréscimo da fibra do curauá na mistura proporcionou uma qualidade superior, no que tange a aparência visual, textura e resistência do papel. A polpa produzida nas proporções de 45% de fibra, 5% de mucilagem e 50% de sobras e aparas de papel, resultou em um papel reciclado com melhor qualidade. O papel reciclado obtido mostrou-se viável técnica e economicamente viável para produção de embalagens, porém há necessidade de melhoria do processo de produção quanto a um melhor aproveitamento da mucilagem, à medida que este resíduo representa uma quantidade expressiva e de baixo custo.Resumo expandido

Efeito do extrato vegetal no desenvolvimento de plantas de curauá (Ananas erectifolius l.B. Smith) em plantio florestal.

Este trabalho foi conduzido no campo experimental Tramontina localizado no município de Aurora do Para#PA com o objetivo de avaliar o efeito do extrato vegetal no desenvolvimento de plantas de curauá (Ananas erectifolius L. B. Smith) em plantio florestal. O extrato vegetal (soro) proveniente do desfibramento das folhas foram recolhidos em balde e em seguida diluído em água formando os tratamentos 100% de soro; 75% de soro e 25% água; 50% de soro e 50% água; 25% de soro e 75% água e um testemunha com 4 repetições cada em delineamento inteiramente casualizado. O extrato vegetal foi aplicado a cada 4 meses e a avaliação realizada em julho de 2010 através das variáveis do número e comprimento de folhas e número de rebentos. Os dados foram analisados por meio de análise de variância, e os valores médios dos parâmetros avaliados foram comparados através do teste SNK utilizando-se o nível de significância de 5%. Resultados parciais indicam um possível efeito do extrato vegetal no crescimento das plantas. Novos ensaios estão em andamento para verificação desses possíveis feitos

Genomic distance under gene substitutions

Dias Vieira Braga M, Machado R, Ribeiro LC, Stoye J. Genomic distance under gene substitutions. BMC Bioinformatics. 2011;12(Suppl 9: Proc. of RECOMB-CG 2011): S8.Background: The distance between two genomes is often computed by comparing only the common markers between them. Some approaches are also able to deal with non-common markers, allowing the insertion or the deletion of such markers. In these models, a deletion and a subsequent insertion that occur at the same position of the genome count for two sorting steps. Results: Here we propose a new model that sorts non-common markers with substitutions, which are more powerful operations that comprehend insertions and deletions. A deletion and an insertion that occur at the same position of the genome can be modeled as a substitution, counting for a single sorting step. Conclusions: Comparing genomes with unequal content, but without duplicated markers, we give a linear time algorithm to compute the genomic distance considering substitutions and double-cut-and-join (DCJ) operations. This model provides a parsimonious genomic distance to handle genomes free of duplicated markers, that is in practice a lower bound to the real genomic distances. The method could also be used to refine orthology assignments, since in some cases a substitution could actually correspond to an unannotated orthology

Cultivo e produção agroambiental sustentável de curauá (Ananas comosus var. erectifolius (L.B.Sm.) Coppens & F.Leal, Bromeliaceae) no Nordeste paraense-PA.

Os produtos florestais não-madeireiros provenientes de sistemas de cultivo com a espécie agronômica curauá estão sendo considerados uma das alternativas de renda para empresas, agricultores e comunidades do Estado do Pará-PA. O estudo do curauá vem sendo desenvolvido a partir de uma parceria entre empresa Tramontina, Universidade Federal Rural de Amazônia, Embrapa Amazônia Oriental com apoio da Fundação de Amparo a Pesquisa do Estado do Pará com objetivo de descrever o cultivo e a produção agroambiental sustentável do curauá (Ananas comosus var. erectifolius (L.B.Sm.) Coppens & F.Leal, Bromeliaceae), no Nordeste Paraense. A uma unidade produtiva fica localizada no campo experimental da empresa Tramontina (2°10?00? latitude sul e 47°32?00 de longitude w) no município de Aurora do Pará-PA. Trimestralmente foram realizados levantamentos do número, comprimento de folhas e número de rebentos de curauá; peso fresco de folhas; rendimento de fibra, produção de soro e mucilagem. Esses dados possibilitaram descrever e indicar condições de cultivo, beneficiamento, rendimento, uso e coeficientes técnicos dos sistemas de cultivo. Essa bromélia possui grande plasticidade e se adapta a diferentes condições ambientais, apresenta diferentes usos e pode ser utilizada para recuperação de áreas degradadas

Factors controlling spatio-temporal variation in carbon dioxide efflux from surface litter, roots, and soil organic matter at four rain forest sites in the eastern Amazon

[1] This study explored biotic and abiotic causes for spatio-temporal variation in soil respiration from surface litter, roots, and soil organic matter over one year at four rain forest sites with different vegetation structures and soil types in the eastern Amazon, Brazil. Estimated mean annual soil respiration varied between 13-17 t C ha(-1) yr(-1), which was partitioned into 0-2 t C ha(-1) yr(-1) from litter, 6-9 t C ha(-1) yr(-1) from roots, and 5-6 t C ha(-1) yr(-1) from soil organic matter. Litter contribution showed no clear seasonal change, though experimental precipitation exclusion over a one-hectare area was associated with a ten-fold reduction in litter respiration relative to unmodified sites. The estimated mean contribution of soil organic matter respiration fell from 49% during the wet season to 32% in the dry season, while root respiration contribution increased from 42% in the wet season to 61% during the dry season. Spatial variation in respiration from soil, litter, roots, and soil organic matter was not explained by volumetric soil moisture or temperature. Instead, spatial heterogeneity in litter and root mass accounted for 44% of observed spatial variation in soil respiration (p < 0.001). In particular, variation in litter respiration per unit mass and root mass accounted for much of the observed variation in respiration from litter and roots, respectively, and hence total soil respiration. This information about patterns of, and underlying controls on, respiration from different soil components should assist attempts to accurately model soil carbon dioxide fluxes over space and time