Avaliação da diversidade genética do banco de germoplasma de pinhão-manso por marcadores moleculares.

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Gravitational wave background from rotating neutron stars

The background of gravitational waves produced by the ensemble of rotating neutron stars (which includes pulsars, magnetars and gravitars) is investigated. A formula for \Omega(f) (commonly used to quantify the background) is derived, properly taking into account the time evolution of the systems since their formation until the present day. Moreover, the formula allows one to distinguish the different parts of the background: the unresolvable (which forms a stochastic background) and the resolvable. Several estimations of the background are obtained, for different assumptions on the parameters that characterize neutron stars and their population. In particular, different initial spin period distributions lead to very different results. For one of the models, with slow initial spins, the detection of the background can be rejected. However, other models do predict the detection of the background by the future ground-based gravitational wave detector ET. A robust upper limit for the background of rotating neutron stars is obtained; it does not exceed the detection threshold of two cross-correlated Advanced LIGO interferometers. If gravitars exist and constitute more than a few percent of the neutron star population, then they produce an unresolvable background that could be detected by ET. Under the most reasonable assumptions on the parameters characterizing a neutron star, the background is too faint. Previous papers have suggested neutron star models in which large magnetic fields (like the ones that characterize magnetars) induce big deformations in the star, which produce a stronger emission of gravitational radiation. Considering the most optimistic (in terms of the detection of gravitational waves) of these models, an upper limit for the background produced by magnetars is obtained; it could be detected by ET, but not by BBO or DECIGO.Comment: 25 pages, 15 figure

Calibration of Nebular Emission-Line Diagnostics: I. Stellar Effective Temperatures

We present a detailed comparison of optical H II region spectra to photoionization models based on modern stellar atmosphere models. We examine both spatially resolved and integrated emission-line spectra of the HII regions DEM L323, DEM L243, DEM L199, and DEM L301 in the Large Magellanic Cloud. The published spectral classifications of the dominant stars range from O7 to WN3, and morphologies range from Stromgren sphere to shell structure. Two of the objects include SNR contamination. The overall agreement with the predictions is generally within 0.2 dex for major diagnostic line ratios. An apparent pattern in the remaining discrepancies is that the predicted T_e is ~1000 K hotter than observed. (Abridged) Our analysis of the complex DEM L199 allows a nebular emission-line test of unprecedented detail for WR atmospheres. Surprisingly, we find no nebular He II 4686 emission, despite the fact that both of the dominant WN3 stars should be hot enough to fully ionize He I in their atmospheres. We confirm that the \eta-prime emission-line parameter is not as useful as hoped for determining the ionizing stellar effective temperature, T*. Both empirically and theoretically, we find that it is insensitive for T* >40 kK, and that it also varies spatially. The shock-contaminated objects show that \eta-prime will also yield a spuriously high T* in the presence of shocks. It is furthermore sensitive to shell morphology. We suggest [Ne III]/Hb as an additional probe of T*. Although it is abundance-dependent, [Ne III]/Hb has higher sensitivity to T*, is independent of morphology, and is insensitive to shocks in our objects. We attempt a first empirical calibration of these nebular diagnostics of T*.Comment: Accepted to ApJS. 37 pages, 14 figures, including 12 jpeg files. Uses emulateapj Latex style file. Single PS file preprint available at http://www.stsci.edu/~oey, along with unabridged abstrac

Sugarcane trash levels in soil affects the fungi but not bacteria in a short-term field experiment.

The sugarcane in Brazil is passing through a management transition that is leading to the abolition of pre-harvest burning. Without burning, large amounts of sugarcane trash is generated, and there is a discussion regarding the utilization of this biomass in the industry versus keeping it in the field to improve soil quality. To study the effects of the trash removal on soil quality, we established an experimental sugarcane plantation with different levels of trash over the soil (0%, 50% and 100% of the original trash deposition) and analyzed the structure of the bacterial and fungal community as the bioindicators of impacts. The soil DNA was extracted, and the microbial community was screened by denaturing gradient gel electrophoresis in two different seasons. Our results suggest that there are no effects from the different levels of trash on the soil chemistry and soil bacterial community. However, the fungal community was significantly impacted, and after twelve months, the community presented different structures among the treatments

Estimativas de coeficientes de repetibilidade e número mínimo de medições para predição do valor genético em pinhão-manso.

Apesar do crescente interesse no plantio de Pinhão Manso, esforços de melhoramento ainda estão em fase inicial. Neste contexto, um importante recurso foi estabelecido visando embasar trabalhos de melhoramento: a montagem de um banco de germoplasma com cerca de 200 acessos. O objetivo deste estudo foi estimar o coeficiente de repetibilidade de sete características, mensuradas em 110 acessos (famílias de irmãos completos) deste banco de germoplasma em diferentes estágios de desenvolvimento. Os resultados demonstram que maiores valores relativos de variância aditiva foram encontrados apenas para produção e altura, e a existência de baixa variância ambiental (tanto de natureza temporária quanto permanente) entre plantas de um mesmo bloco. Devido aos altos valores de repetibilidade encontrados para todas as características, cerca de três mensurações são necessárias para predizer, acurada e eficientemente, o real valor de melhoramento de um dado individuo

Impacto da cana na comunidade de desnitrificantes, fluxo de N20 e potencial de desnitrificação do solo de cerrado.

O Cerrado é um importante componente do bioma brasileiro, possui enorme diversidade e endemismo de espécies, e vem perdendo espaço para o plantio de cana de açúcar. A mudança no uso do solo altera a qualidade, composição e a estrutura das comunidades microbianas do solo. Este trabalho relacionou o plantio e manejo da cana de açúcar no solo de Cerrado com as alterações na estrutura da comunidade bacteriana desnitrificante e a relação destas com a desnitrificação potencial e fluxo de óxido nitroso do solo. Foram selecionadas uma área de Cerrado Nativo e duas áreas sob plantio de cana com diferentes manejos, uma de Cana Crua e outra de Cana Queimada. Foram feitas análises da estrutura da comunidade de bactérias desnitrificantes por PCR/DGGE, das taxas de desnitrificação potencial, do teor de nitrato e cálculo de WFP. A mudança no uso do solo provocou alterações marcantes na estrutura das comunidades bacterianas, e no potencial de desnitrificação do solo, mas produziu reflexos não significativos no fluxo de N2O do solo

Gas Emission Spectrum in the Irr Galaxy IC 10

Spectroscopic long-slit observations of the dwarf Irr galaxy IC 10 were conducted at the 6-m Special Astrophysical Observatory telescope with the SCORPIO focal reducer. The ionized-gas emission spectra in the regions of intense current star formation were obtained for a large number of regions in IC 10. The relative abundances of oxygen, N+, and S+ in about twenty HII regions and in the synchrotron superbubble were estimated. We found that the galaxy-averaged oxygen abundance is 12 + log(O/H) = 8.17 +- 0.35 and the metallicity is Z = 0.18 +- 0.14 Z_sun. Our abundances estimated from the strong emission lines are found to be more reliable than those obtained by comparing diagnostic diagrams with photoionization models.Comment: Abridged; accepted in Astronomy Letter

Estrutura da comunidade bacteriana e agregação do solo sob cerrado e cana-de-açúcar, em Goiás.

O objetivo desse trabalho é estudar de que forma o uso e manejo do solo sob cultivo de cana de açúcar alteram o estado de agregação do solo e a estrutura da comunidade bacteriana de classes representativas de macro e de microagregados

Polycyclic aromatic hydrocarbons in the dwarf galaxy IC 10

Infrared observations from the Spitzer Space Telescope archive are used to study the dust component of the interstellar medium in the IC~10 irregular galaxy. Dust distribution in the galaxy is compared to the distributions of H$\alpha$ and [SII] emission, neutral hydrogen and CO clouds, and ionizing radiation sources. The distribution of polycyclic aromatic hydrocarbons (PAH) in the galaxy is shown to be highly non-uniform with the mass fraction of these particles in the total dust mass reaching 4%. PAHs tend to avoid bright HII regions and correlate well with atomic and molecular gas. This pattern suggests that PAHs form in the dense interstellar gas. We propose that the significant decrease of the PAH abundance at low metallicity is observed not only globally (at the level of entire galaxies), but also locally (at least, at the level of individual HII regions). We compare the distribution of the PAH mass fraction to the distribution of high-velocity features, that we have detected earlier in wings of H$\alpha$ and SII lines, over the entire available galaxy area. No conclusive evidence for shock destruction of PAHs in the IC~10 galaxy could be found.Comment: Accepted for publication in Astronomy Report