Oat growth under different nitrogen doses in an eucalyptus alley cropping system in subtropical Brazil.

Foi realizada uma análise de crescimento para verificar como a aveia (Avena sativa L. cv. IPR 126) cultivada para grãos responde a um sistema agroflorestal (SAF) com eucaliptos (Eucalyptus dunnii Maiden) no subtrópico brasileiro. A hipótese deste trabalho é que a resposta de crescimento da aveia não é modificada pelo nitrogênio em distâncias relativas a faixas de eucaliptos. O objetivo deste estudo foi determinar como o crescimento da aveia é influenciado por níveis de nitrogênio (12 e 80 kg ha-1 de N) em cinco posições equidistantes entre faixas de linhas duplas de eucaliptos [20 m (4 m x 3 m)] em SAF e em agricultura tradicional de plantio direto. O experimento foi em faixas no delineamento de blocos ao acaso com quatro repetições. Foram avaliadas as taxas de crescimento relativo e de assimilação líquida, fração de massa foliar e taxa de enchimento relativo da panícula. O nitrogênio alterou a resposta do crescimento diferentemente em posições relativas às faixas de árvores, portanto diferentes doses de nitrogênio devem ser utilizadas nestas posições para aumentar o crescimento da aveia

Hydrous Phase Relations and Trace Element Partitioning Behaviour in Calcareous Sediments at Subduction-Zone Conditions

We report the results of experiments on two natural marine sediments with different carbonate contents (calcareous clay: CO2 = 6·1 wt %; marl: CO2 = 16·2 wt %) at subduction-zone conditions (3 GPa, 750-1200°C). Water (7-15 wt %) was added to the starting materials to simulate the effects of external water addition from within the subducting slab. The onset of melting is at 760°C in water-rich experiments; melt becomes abundant by 800°C. In contrast, the onset of melting in published, water-poor experiments occurs at variable temperatures with the production of significant melt fractions being restricted to more than 900°C (phengite-out). The different solidus temperatures (Tsolidus) can be ascribed to variable fluid XH2O [H2O/(CO2 + H2O)], which, in turn, depends on bulk K2O, H2O and CO2. Partial melts in equilibrium with residual garnet, carbonate, quartz/coesite, epidote, rutile, kyanite, phengite, and clinopyroxene are granitic in composition, with substantial dissolved volatiles. Supersolidus runs always contain both silicate melt and solute-rich fluid, indicating that experimental conditions lie below the second critical endpoint in the granite-H2O-CO2 system. Carbonatite melt coexists with silicate melt and solute-rich fluid above 1100°C in the marl. The persistence of carbonate to high temperature, in equilibrium with CO2-rich hydrous melts, provides a mechanism to both supply CO2 to arc magmas and recycle carbon into the deep Earth. The trace element compositions of the experimental glasses constrain the potential contribution of calcareous sediment to arc magmas. The presence of residual epidote and carbonate confers different trace element characteristics when compared with the trace element signal of Ca-poor marine sediments (e.g. pelagic clays). Notably, epidote retains Th and light rare earth elements, such that some melts derived from calcareous sediments have elevated Ba/Th and U/Th, and low La/SmPUM, thereby resembling fluids conventionally ascribed to altered oceanic crust. Our results emphasize the importance of residual mineralogy, rather than source lithology, in controlling the trace element characteristics of slab-derived fluid

Latin American platform comparative critical analysis. Learning from the KASSA platforms' reports.

1 CD-ROM. Projeto DG-Research - Contract nº GOCE-CT-2004-505582

Plantio direto, adubação verde e suplementação com esterco de aves na produção orgânica de berinjela.

Sob manejo orgânico, foram avaliados, em Seropédica, RJ, os sistemas de plantio direto da berinjela(Solanum melongena) nas palhadas de Crotalaria juncea (crotalária), Pennisetum glaucum (milheto, cv. BRS 1501)e vegetação espontânea (pousio), em comparação com o plantio convencional (aração e gradagem ou enxada rotativa). Simultaneamente, foram avaliados três tipos de cultivo: berinjela em monocultura, em consórcio com crotalária e em consórcio com caupi (Vigna unguiculata, cv. Mauá). Não houve diferença entre os sistemas de plantio direto e convencional quanto à produção comercial da berinjela. A palhada da crotalária foi mais eficiente que a do milheto e do pousio para cobertura morta do solo e conseqüentemente o controle de plantas espontâneas foi maior. O cultivo simultâneo com as leguminosas não acarretou redução da produtividade da berinjela.Em um segundo estudo, foram comparados plantio direto (palhadas de crotalária e da vegetação espontânea) e plantio convencional, combinados com doses crescentes de cama de aviário (0, 100, 200 e 400 kg ha-1 de N)aplicada em cobertura. Em termos de aporte de biomassa, a crotalária foi novamente superior à vegetação espontânea.A berinjela respondeu à adubação orgânica, com produtividade máxima de 50,6 t ha-1 , correspondendo à maior dose empregada, contra 36,9 t ha-1 referentes ao controle

The Protein Data Bank: Present status and future plans

The Protein Data Bank (PDB) archival database of dimensional structures of biological macromolecules, an international resource facility, contains information on protein, DNA, RNA, virus and carbohydrate structures. While the vast majority of PDB entries represent crystal structures, results from NMR and theoretical modeling strudies also are included. PDB, which in July 1992 contained 957 atomic coordinate entries, currently is experiencing a time of explosive growth. The present deposition rate is ca. 50 structures per month, doubling in less than two years. Responding to the challenge posed by this. rising data flow, over the past 18 months PDB has attracted increased funding to implement important enhancements of the resource. A rapid pre-release of entries pending for input was inaugurated in April 1992, and a substantial fraction of the accumulated backlog of pending entries is now available via FTP and e-mail in prerelease form. Extrapolation of current data rates suggests that by the year 2000 PDB may contain over 25,000 structures. PDB`s plans, to manage this voluminous amount of data, include the development of PDB-AUTHORIN software to allow depositors to do most of the preparation and validation of their own entries, and a comprehensive upgrade of PDB contents to add new data items and convert the current interchange format to the Crystallographic Information File (CIF) standard established by the International Union of Crystallography (IUCr)

Subduction factory: 4. Depth‐dependent flux of H 2 O from subducting slabs worldwide

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95328/1/jgrb16727.pd

Oxygen-sensing neurons reciprocally regulate peripheral lipid metabolism via neuropeptide signaling in <i>Caenorhabditis elegans</i>

<div><p>The mechanisms by which the sensory environment influences metabolic homeostasis remains poorly understood. In this report, we show that oxygen, a potent environmental signal, is an important regulator of whole body lipid metabolism. <i>C</i>. <i>elegans</i> oxygen-sensing neurons reciprocally regulate peripheral lipid metabolism under normoxia in the following way: under high oxygen and food absence, URX sensory neurons are activated, and stimulate fat loss in the intestine, the major metabolic organ for <i>C</i>. <i>elegans</i>. Under lower oxygen conditions or when food is present, the BAG sensory neurons respond by repressing the resting properties of the URX neurons. A genetic screen to identify modulators of this effect led to the identification of a BAG-neuron-specific neuropeptide called FLP-17, whose cognate receptor EGL-6 functions in URX neurons. Thus, BAG sensory neurons counterbalance the metabolic effect of tonically active URX neurons via neuropeptide communication. The combined regulatory actions of these neurons serve to precisely tune the rate and extent of fat loss to the availability of food and oxygen, and provides an interesting example of the myriad mechanisms underlying homeostatic control.</p></div