Quantificação do carbono das substâncias húmicas em diferentes sistemas de uso do solo e épocas de avaliação.

A quantificação do carbono nas diferentes frações da matéria orgânica do solo (MOS) torna-se necessária devido ao interesse de se conhecer o potencial de captura e armazenamento do carbono nos diferentes sistemas de uso do solo. O objetivo deste trabalho foi quantificar o carbono das substâncias húmicas em diferentes sistemas de uso do solo e épocas de avaliação e correlacioná-lo com algumas propriedades químicas e físicas do solo. Os sistemas selecionados foram: preparo convencional (PC-milho/feijão), plantio direto (PD-berinjela/milho), consórcio maracujá/Desmodium sp, cultivo com figo e sistema agroflorestal. As amostras de solo foram coletadas em duas profundidades (0-5 e 5-10 cm) e épocas (17/11/2005–verão e 23/6/2006-inverno). Foi determinado o carbono orgânico total (COT) e realizado o fracionamento químico da MOS, quantificando-se o carbono da fração humina (C-HUM), fração ácido húmico (C-FAH) e fração ácido fúlvico (C-FAF). O C-HUM constituiu a maior parte do COT, havendo correlação significativa com o COT em todos os sistemas avaliados e estações. Analisando o C-FAH foi possível identificar alterações no solo relacionadas aos sistemas de uso, na profundidade de 0-5 cm e no verão, destacando-se o PD com os maiores teores. Com o C-FAF ocorreu este mesmo comportamento, mas na profundidade de 5-10 cm e no inverno, destacando-se o PC com maiores valores. Foram verificadas correlações significativas entre Valor S, Valor T e DMP em todos os sistemas, com exceção da área de PC. O PD aumenta os teores de C-FAH, nas duas profundidades e nas duas estações, quando comparado ao PC do solo

CORRELAÇÃO GENÉTICA, FENOTÍPICA E AMBIENTAL EM CARACTERÍSTICAS DE CRESCIMENTO DE BOVINOS DA RAÇA NELORE VARIEDADE MOCHA

The objective of this work was estimate the genetic correlations, environmental and phenotypic on the birth weight (WB) and on the 205 (W205), 365 (W365) and 550 (W550) days of age, in animals of the polled nellore breed from Bahia state. The analyses were carried out by software MTDFREML. The genetic correlations were 0.08 (WB and W205), 0.00 (WB and W365), - 0.14 (WB and W550), 0.90 (W205 and W365), 0.81 (W205 and W550) and 0.97 (W205 and W550). The environmental correlations were 0.12 (WB and W205), 0.11 (WB and W365) and 0.16 (WB and W550), 0.35 (W205 and W365), 0.13 (W205 and W550) and 0.54 (W365 and W550). The phenotypic correlations were 0.09 (WB and W205), 0.05 (WB and W365), 0.00 (WB and W550), 0.75 (W205 and W365), 0.65 (W205 and W550) and 0.87 (W365 and W550). The birth weight presented weak genetic, environmental, and phenotypic associations with the others weighting. On the other hand, the values gotten for the genetic correlations between the other weighting, indicates that the selection for weight in young ages will promote changes on the future weights of the animal.O objetivo deste trabalho foi estimar as correlações genéticas, fenotípicas e ambientais sobre os pesos ao nascimento (PN) e aos 205 (P205), 365 (P365) e 550 (P550) dias de idade, em animais da raça Nelore Mocha, criados no estado da Bahia. As análises bi-características foram realizadas através do programa MTDFREML. As correlações genéticas foram iguais a 0,08 (PN e P205), 0,00 (PN e P365), - 0,14 (PN e P550), 0,90 (P205 e P365), 0,81, (P205 e P550) e 0,97 (P365 e P550). As correlações ambientais foram 0,12 (PN e P205), 0,11 (PN e P365), 0,16 (PN e P550), 0,35 (P205 e P365), 0,13 (P205 e P550) e 0,54 (P365 e P550). Os valores obtidos para as correlações fenotípicas foram 0,09 (PN e P205), 0,05 (PN e P365), 0,00 (PN e P550), 0,75 (P205 e P365) 0,65 (P205 e P550) e 0,87 (P365 e P550). O peso ao nascimento apresentou ausência de associações genéticas, ambientais e fenotípicas com as demais pesagens. Por outro lado, os valores obtidos para as correlações genéticas entre as outras pesagens, indicam que a seleção para peso em idades jovens deverá promover mudanças nos pesos posteriores dos animais

Prospects for asteroseismology

The observational basis for asteroseismology is being dramatically strengthened, through more than two years of data from the CoRoT satellite, the flood of data coming from the Kepler mission and, in the slightly longer term, from dedicated ground-based facilities. Our ability to utilize these data depends on further development of techniques for basic data analysis, as well as on an improved understanding of the relation between the observed frequencies and the underlying properties of the stars. Also, stellar modelling must be further developed, to match the increasing diagnostic potential of the data. Here we discuss some aspects of data interpretation and modelling, focussing on the important case of stars with solar-like oscillations.Comment: Proc. HELAS Workshop on 'Synergies between solar and stellar modelling', eds M. Marconi, D. Cardini & M. P. Di Mauro, Astrophys. Space Sci., in the press Revision: correcting abscissa labels on Figs 1 and

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

Hydrothermal vents and methane seeps: rethinking the sphere of influence

Although initially viewed as oases within a barren deep ocean, hydrothermal vents and methane seep chemosynthetic communities are now recognized to interact with surrounding ecosystems on the sea floor and in the water column, and to affect global geochemical cycles. The importance of understanding these interactions is growing as the potential rises for disturbance of the systems from oil and gas extraction, seabed mining and bottom trawling. Here we synthesize current knowledge of the nature, extent and time and space scales of vent and seep interactions with background systems. We document an expanded footprint beyond the site of local venting or seepage with respect to elemental cycling and energy flux, habitat use, trophic interactions, and connectivity. Heat and energy are released, global biogeochemical and elemental cycles are modified, and particulates are transported widely in plumes. Hard and biotic substrates produced at vents and seeps are used by "benthic background" fauna for attachment substrata, shelter, and access to food via grazing or through position in the current, while particulates and fluid fluxes modify planktonic microbial communities. Chemosynthetic production provides nutrition to a host of benthic and planktonic heterotrophic background species through multiple horizontal and vertical transfer pathways assisted by flow, gamete release, animal movements, and succession, but these pathways remain poorly known. Shared species, genera and families indicate that ecological and evolutionary connectivity exists among vents, seeps, organic falls and background communities in the deep sea: the genetic linkages with inactive vents and seeps and background assemblages however, are practically unstudied. The waning of venting or seepage activity generates major transitions in space and time that create links to surrounding ecosystems, often with identifiable ecotones or successional stages. The nature of all these interactions is dependent on water depth, as well as regional oceanography and biodiversity. Many ecosystem services are associated with the interactions and transitions between chemosynthetic and background ecosystems, for example carbon cycling and sequestration, fisheries production, and a host of non-market and cultural services. The quantification of the sphere of influence of vents and seeps could be beneficial to better management of deep-sea environments in the face of growing industrialization