14,062 research outputs found

    Características das cultivares de arroz recomendadas para Rondônia.

    Get PDF
    A EMBRAPA/Centro de Pesquisa Agroflorestal de Rondônia (CPAF-Rondônia) vem conduzindo, anualmente, em colaboração com a EMBRAPA Centro Nacional de Pesquisa de Arroz e Feijão (CNPAF), um Programa de Melhoramento Genético do Arroz, onde procura avaliar e selecionar genótipos agronomicamente superiores, com o objetivo de recomendar aos produtores rondonienses, novas cultivares que apresentam alto potencial produtivo, além de resistência a doenças e ao acamamento, e boa qualidade de grãos.bitstream/item/112982/1/CPAFRO-Documentos-29.pd

    An X-ray Atlas of Groups of Galaxies

    Full text link
    A search was conducted for a hot intragroup medium in 109 low-redshift galaxy groups observed with the ROSAT PSPC. Evidence for diffuse, extended X-ray emission is found in at least 61 groups. Approximately one-third of these detections have not been previously reported in the literature. Most of the groups are detected out to less than half of the virial radius with ROSAT. Although some spiral-rich groups do contain an intragroup medium, diffuse emission is restricted to groups that contain at least one early-type galaxy.Comment: 39 pages, 12 figures, to appear in The Astrophysical Journal Sup

    Probing dipolar effects with condensate shape oscillation

    Full text link
    We discuss the low energy shape oscillations of a magnetic trapped atomic condensate including the spin dipole interaction. When the nominal isotropic s-wave interaction strength becomes tunable through a Feshbach resonance (e.g. as for 85^{85}Rb atoms), anisotropic dipolar effects are shown to be detectable under current experimental conditions [E. A. Donley {\it et al.}, Nature {\bf 412}, 295 (2001)].Comment: revised version, submitte

    Carbon Nitrogen, and Oxygen Galactic Gradients: A Solution to the Carbon Enrichment Problem

    Full text link
    Eleven models of Galactic chemical evolution, differing in the carbon, nitrogen,and oxygen yields adopted, have been computed to reproduce the Galactic O/H values obtained from H II regions. All the models fit the oxygen gradient, but only two models fit also the carbon gradient, those based on carbon yields that increase with metallicity due to stellar winds in massive stars (MS) and decrease with metallicity due to stellar winds in low and intermediate mass stars (LIMS). The successful models also fit the C/O versus O/H evolution history of the solar vicinity obtained from stellar observations. We also compare the present day N/H gradient and the N/O versus O/H and the C/Fe, N/Fe, O/Fe versus Fe/H evolution histories of the solar vicinity predicted by our two best models with those derived from H II regions and from stellar observations. While our two best models fit the C/H and O/H gradients as well as the C/O versus O/H history, only Model 1 fits well the N/H gradient and the N/O values for metal poor stars but fails to fit the N/H values for metal rich stars. Therefore we conclude that our two best models solve the C enrichment problem, but that further work needs to be done on the N enrichment problem. By adding the C and O production since the Sun was formed predicted by Models 1 and 2 to the observed solar values we find an excellent agreement with the O/H and C/H values of the solar vicinity derived from H II regions O and C recombination lines. One of the most important results of this paper is that the fraction of carbon due to MS and LIMS in the interstellar medium is strongly dependent on time and on the galactocentric distance; at present about half of the carbon in the interstellar medium of the solar vicinity has been produced by MS and half by LIMS.Comment: 34 pages, 6 tables, 7 figures. Accepted for publication in Ap

    Sensitivity of the marine benthic copepod Tisbe biminiensis (copepoda, harpacticoida) to potassium dichromate and sediment particle size

    Get PDF
    For the future use of the marine benthic copepod Tisbe biminiensis in solid-phase sediment toxicological bioassays, the present study investigated the effect of muddy sediment from the Maracaípe estuary (northeastern Brazil), sediment particle size and the reference toxicant potassium dichromate on the species. Muddy sediment from Maracaípe can be used as control sediment, since it does not interfere in the copepod life-cycle and has metal contamination levels that are unlikely to produce any detrimental biological effects on benthic invertebrates. Neither survival nor fecundity was affected by grain size, suggesting that this species can be used with any kind of sediment from muddy to sandy. The sensitivity of T. biminiensis to K2Cr2O7 in acute tests was similar to that of other organisms. The LC50 (lethal concentration to 50% of the test organisms) medium values for T. biminiensis were 7.51, 4.68 and 3.19 mg L-1 for Cr in 48, 72 and 96 h, respectively. These results suggest that T. biminiensis is a promising organism for use in solid-phase sediment toxicity assessments.Visando o uso futuro do copépodo marinho bentônico Tisbe biminiensis em bioensaios toxicológicos de sedimentos na fase sólida, o presente estudo investigou o efeito do sedimento lamoso do estuário de Maracaípe (Nordeste do Brasil). Foram considerados a granolometria e o tóxico de referência dicromato de potássio sobre a espécie. O sedimento lamoso de Maracaípe pode ser usado como controle, uma vez que não interfere no ciclo de vida do copépodo e possui níveis de contaminação de metais que não causariam efeitos biológicos em invertebrados bentônicos. Nem a sobrevivência ou fecundidade foi afetada pelo tamanho do grão, sugerindo que esta espécie pode ser usada com qualquer tipo de sedimento, de lama a areia. A sensibilidade de T. biminiensis ao K2Cr2O7 em testes agudos foi similar a de outros organismos. Os valores de CL50 (concentração letal a 50% dos organismos) para T. biminiensis foram em média 7,51, 4,68 e 3,19 mg L-1 para o Cr em 48, 72 e 96h, respectivamente. Estes resultados sugerem que T. biminiensis é um organismo promissor para uso em avaliações de toxicidade com a fase sólida do sedimento

    Identification of a novel deletion in SURF1 gene: Heterogeneity in Leigh syndrome with COX deficiency

    Get PDF
    Leigh syndrome (LS) is a rare, progressive neurodegenerative mitochondrial disorder of infancy. It is a genetically heterogeneous disease. The mutations in SURF1 gene are the most frequently known cause. Here two cases of LS likely caused by SURF1 gene variants are reported: a 39-year-old male patient with a novel homozygous deletion (c.-11_13del), and a case of a 6-year-old boy with the same deletion and a nonsense mutation (c.868dupT), both in heterozygosity. Blue native PAGE showed absence of assembled complex IV. This is the first report of a variant that may abolish the SURF1 gene initiation codon in two LS patients.info:eu-repo/semantics/publishedVersio

    Heat Treated NiP–SiC Composite Coatings: Elaboration and Tribocorrosion Behaviour in NaCl Solution

    Get PDF
    Tribocorrosion behaviour of heat-treated NiP and NiP–SiC composite coatings was investigated in a 0.6 M NaCl solution. The tribocorrosion tests were performed in a linear sliding tribometer with an electrochemical cell interface. It was analyzed the influence of SiC particles dispersion in the NiP matrix on current density developed, on coefficient of friction and on wear volume loss. The results showed that NiP–SiC composite coatings had a lower wear volume loss compared to NiP coatings. However, the incorporation of SiC particles into the metallic matrix affects the current density developed by the system during the tribocorrosion test. It was verified that not only the volume of co-deposited particles (SiC vol.%) but also the number of SiC particles per coating area unit (and consequently the SiC particles size) have made influence on the tribocorrosion behaviour of NiP–SiC composite coatings

    Comportamento diferencial do estado nutricional de cultivares de mamoeiros avaliados por meio das análises de macronutrientes em limbos e pecíolos foliares em condições edafoclimáticas do Amazonas.

    Get PDF
    Iniciou-se este trabalho com o objetivo geral de introduzir, avaliar e identificar cultivares adaptadas às condições de clima e solo do Estado do Amazonas, portadoras de elevado potencial produtivo e de características agronômicas favoráveis à qualidade, para futuras recomendações aos produtores. Nesta etapa, o objetivo específico foi avaliar o comportamento diferencial de quinze cultivares de mamoeiros em relação aos teores de macronutrientes nos tecidos do limbo foliar e do pecíolo, bem como comparar os teores entre essas duas partes da folha amostradas
    corecore