Pathogenic variation of Phakopsora pachyrhizi populations in Brazil.

The obligate basidiomycete Phakopsora pachyrhizi is the causal agent of soybean rust that has potential to reduce the yield of soybean drastically. Soybean production in Brazil has been threatened by the rust since the pathogen was first discovered in 2001. To understand pathogenic variation of the rust populations in South America, an evaluation system for soybean rust resistance has been constructed using a set of 16 differential varieties. In this study, the evaluation system was used to investigate pathogenic variation among the P. pachyrhizi populations in Brazil. Samples of P. pachyrhizi were collected from the diseased soybeans in Brazil in the 2007-2008 and 2008-2009 soybean cultivation seasons. In the first season, two rust samples showed similar pattern of the infection types on the differential set, suggesting that the same or similar pathogen population was present in the two locations. The other samples were likely different pathogenic populations. In the second season, different patterns of the infection types were found among the samples. Comparison of the evaluation data from the two seasons demonstrated that pathogenic variation between the seasons was detected in the populations from Rio Grande do Sul and Paraná but was not remarkable in those from Rondônia. This study provides useful knowledge about P. pachyrhizi populations in Brazil to identify the resistant soybean genotypes and target effective cultivars against certain pathogen populations.Edição do Proceedings of the National Soybean Rust Symposium, New Orleans, 2009

A Preservação Digital de Documentos Governamentais: Um Problema de Interoperabilidade?

Prover à sociedade o acesso à informação governamental é um assunto em evidência. A disponibilização dos dados na internet visando a transparência das ações do governo e o reuso da informação, têm sido os principais focos. No entanto, prover o acesso à informação digital ao longo do tempo é um assunto que ainda carece da necessária atenção. Este trabalho apresenta os conceitos e fundamentos desenvolvidos para a preservação de longo prazo da informação codificada em objetos digitais. O estudo teve como objetivo relacionar os conceitos do modelo Open Archives Information System à estrutura do Open Document Format, no contexto da preservação digital de longo prazo. Visa, com isso, contribuir para o processo de sedimentação dos conceitos de interoperabilidade temporal e de preservação dos documentos digitais do governo, ambos ainda ausentes nas arquiteturas de interoperabilidade dos programas de governo eletrônico.Sociedad Argentina de Informática e Investigación Operativ

A Preservação Digital de Documentos Governamentais: Um Problema de Interoperabilidade?

Prover à sociedade o acesso à informação governamental é um assunto em evidência. A disponibilização dos dados na internet visando a transparência das ações do governo e o reuso da informação, têm sido os principais focos. No entanto, prover o acesso à informação digital ao longo do tempo é um assunto que ainda carece da necessária atenção. Este trabalho apresenta os conceitos e fundamentos desenvolvidos para a preservação de longo prazo da informação codificada em objetos digitais. O estudo teve como objetivo relacionar os conceitos do modelo Open Archives Information System à estrutura do Open Document Format, no contexto da preservação digital de longo prazo. Visa, com isso, contribuir para o processo de sedimentação dos conceitos de interoperabilidade temporal e de preservação dos documentos digitais do governo, ambos ainda ausentes nas arquiteturas de interoperabilidade dos programas de governo eletrônico.Sociedad Argentina de Informática e Investigación Operativ

A Preservação Digital de Documentos Governamentais: Um Problema de Interoperabilidade?

Prover à sociedade o acesso à informação governamental é um assunto em evidência. A disponibilização dos dados na internet visando a transparência das ações do governo e o reuso da informação, têm sido os principais focos. No entanto, prover o acesso à informação digital ao longo do tempo é um assunto que ainda carece da necessária atenção. Este trabalho apresenta os conceitos e fundamentos desenvolvidos para a preservação de longo prazo da informação codificada em objetos digitais. O estudo teve como objetivo relacionar os conceitos do modelo Open Archives Information System à estrutura do Open Document Format, no contexto da preservação digital de longo prazo. Visa, com isso, contribuir para o processo de sedimentação dos conceitos de interoperabilidade temporal e de preservação dos documentos digitais do governo, ambos ainda ausentes nas arquiteturas de interoperabilidade dos programas de governo eletrônico.Sociedad Argentina de Informática e Investigación Operativ

The late stages of evolution of helium star-neutron star binaries and the formation of double neutron star systems

With a view to understanding the formation of double neutron-stars (DNS), we investigate the late stages of evolution of helium stars with masses of 2.8 - 6.4 Msun in binary systems with a 1.4 Msun neutron-star companion. We found that mass transfer from 2.8 - 3.3 Msun helium stars and from 3.3 - 3.8 Msun in very close orbits (P_orb > 0.25d) will end up in a common-envelope (CE) and spiral-in phase due to the development of a convective helium envelope. If the neutron star has sufficient time to complete the spiraling-in process before the core collapses, the system will produce very tight DNSs (P_orb ~ 0.01d) with a merger timescale of the order of 1 Myr or less. These systems would have important consequences for the detection rate of GWR and for the understanding of GRB progenitors. On the other hand, if the time left until the explosion is shorter than the orbital-decay timescale, the system will undergo a SN explosion during the CE phase. Helium stars with masses 3.3 - 3.8 Msun in wider orbits (P_orb > 0.25d) and those more massive than 3.8 Msun do not go through CE evolution. The remnants of these massive helium stars are DNSs with periods in the range of 0.1 - 1 d. This suggests that this range of mass includes the progenitors of the galactic DNSs with close orbits (B1913+16 and B1534+12). A minimum kick velocity of 70 km/s and 0 km/s (for B1913+16 and B1534+12, respectively) must have been imparted at the birth of the pulsar's companion. The DNSs with wider orbits (J1518+4904 and probably J1811-1736) are produced from helium star-neutron star binaries which avoid RLOF, with the helium star more massive than 2.5 Msun. For these systems the minimum kick velocities are 50 km/s and 10 km/s (for J1518+4904 and J1811-1736, respectively).Comment: 16 pages, latex, 12 figures, accepted for publication in MNRA

Cosmic ray tests of a GEM-based TPC prototype operated in Ar-CF4-isobutane gas mixtures

Argon with an admixture of CF4 is expected to be a good candidate for the gas mixture to be used for a time projection chamber (TPC) in the future linear collider experiment because of its small transverse diffusion of drift electrons especially under a strong magnetic field. In order to confirm the superiority of this gas mixture over conventional TPC gases we carried out cosmic ray tests using a GEM-based TPC operated mostly in Ar-CF4-isobutane mixtures under 0 - 1 T axial magnetic fields. The measured gas properties such as gas gain and transverse diffusion constant as well as the observed spatial resolution are presented.Comment: 22 pages, 18 figures. Published in Nuclear Instruments and Methods in Physics Research A. Fig. 3 in the introduction was corrected since it had not been properly normalized. Minor corrections and no changes in the conclusio

Ultraviolet, Optical, and X-Ray Observations of the Type Ia Supernova 2005am with Swift

We present ultraviolet and optical light curves in six broadband filters and grism spectra obtained by Swift's Ultraviolet/Optical Telescope for the Type Ia supernova SN2005am. The data were collected beginning about four days before the B-band maximum, with excellent coverage of the rapid decline phase and later observations extending out to 69 days after the peak. The optical and near UV light curve match well those of SN1992A. The other UV observations constitute the first set of light curves shorter than 2500 Angstroms and allow us to compare the light curve evolution in three UV bands. The UV behavior of this and other low redshift supernovae can be used to constrain theories of progenitor evolution or to interpret optical light curves of high redshift supernovae. Using Swift's X-Ray Telescope, we also report the upper limit to SN2005am's X-ray luminosity to be 1.77 x 10^40 erg s^-1 in the 0.3--10 keV range from 58,117 s of exposure time.Comment: 15 pages, including 3 figures and 2 tables, submitted to Astrophysical Journa

Niche divergence facilitated by fine-scale ecological partitioning in a recent cichlid fish adaptive radiation

Ecomorphological differentiation is a key feature of adaptive radiations, with a general trend for specialization and niche expansion following divergence. Ecological opportunity afforded by invasion of a new habitat is thought to act as an ecological release, facilitating divergence, and speciation. Here, we investigate trophic adaptive morphology and ecology of an endemic clade of oreochromine cichlid fishes (Alcolapia) that radiated along a herbivorous trophic axis following colonization of an isolated lacustrine environment, and demonstrate phenotype-environment correlation. Ecological and morphological divergence of the Alcolapia species flock are examined in a phylogenomic context, to infer ecological niche occupation within the radiation. Species divergence is observed in both ecology and morphology, supporting the importance of ecological speciation within the radiation. Comparison with an outgroup taxon reveals large-scale ecomorphological divergence but shallow genomic differentiation within the Alcolapia adaptive radiation. Ancestral morphological reconstruction suggests lake colonization by a generalist oreochromine phenotype that diverged in Lake Natron to varied herbivorous morphologies akin to specialist herbivores in Lakes Tanganyika and Malawi

Nova light curves from the Solar Mass Ejection Imager (SMEI) - II. The extended catalogue

We present the results from observing nine Galactic novae in eruption with the Solar Mass Ejection Imager (SMEI) between 2004 and 2009. While many of these novae reached peak magnitudes that were either at or approaching the detection limits of SMEI, we were still able to produce light curves that in many cases contained more data at and around the initial rise, peak, and decline than those found in other variable star catalogs. For each nova, we obtained a peak time, maximum magnitude, and for several an estimate of the decline time (t2). Interestingly, although of lower quality than those found in Hounsell et al. (2010a), two of the light curves may indicate the presence of a pre-maximum halt. In addition the high cadence of the SMEI instrument has allowed the detection of low amplitude variations in at least one of the nova light curves