Variabilidade temporal da produtividade da soja após conversão do preparo convencional para o sistema plantio direto.

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Qualidade física do solo em um sistema de integração lavoura-pécuaria com diferentes pressões de pastejo.

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Relação entre a resistência do solo à penetração determinada por dois métodos e a pressão de pastejo, em um sistema de integração lavoura-pecuária.

Em pastagens constituídas por forrageiras tropicais perenes, o impacto das pressões de pastejo sobre o grau de compactação do solo tem sido pouco estudado. Com o objetivo de avaliar o efeito da pressão de pastejo sobre a resistência a penetração (RP), determinada por dois métodos, em um sistema de iLP, implantou-se um experimento sobre um Latossolo Vermelho distroférrico. As pressões de pastejo equivaleram a 6,88; 9,38; e 16,47 unidades animais por hectare, aplicadas numa pastagem de Brachiaria brizantha durante 19 dias. Esses tratamentos foram comparados a uma testemunha sem pastejo. Amostras indeformadas de solo, coletadas nas camadas de 0,0-0,05; 0,05-0,1; 0,1-0,2; e 0,2-0,3 m e equilibradas a uma tensão de 100 kPa, foram utilizadas para a determinação da RP em laboratório, por meio de um penetrômetro estático de bancada. Nessas mesmas profundidades, determinou-se a RP a campo, mediante o uso de um penetrômetro de impacto modelo IAA/Planalsucar- Stolf. Independentemente da pressão de pastejo, o pisoteio bovino aumentou a RP na camada de 0,0- 0,1 m. Na maior pressão de pastejo (16,47 UA ha-1), o pisoteio aumentou a RP a maiores profundidades (0,1-0,2 m). A magnitude dos valores de RP, assim como a resposta dos mesmos às pressões de pastejo, variaram em função do penetrômetro utilizado (dinâmico ou estático de bancada)

Designing hollow nano gold golf balls.

Hollow/porous nanoparticles, including nanocarriers, nanoshells, and mesoporous materials have applications in catalysis, photonics, biosensing, and delivery of theranostic agents. Using a hierarchical template synthesis scheme, we have synthesized a nanocarrier mimicking a golf ball, consisting of (i) solid silica core with a pitted gold surface and (ii) a hollow/porous gold shell without silica. The template consisted of 100 nm polystyrene beads attached to a larger silica core. Selective gold plating of the core followed by removal of the polystyrene beads produced a golf ball-like nanostructure with 100 nm pits. Dissolution of the silica core produced a hollow/porous golf ball-like nanostructure

Variabilidade de cevada (Hordeum vulgare L.) em relação à tolerância ao alumínio.

Orientadora: Carla Andrea Delatorre, Coorientador: Jorge Fernando Pereira

Habitability Assessment at Gale Crater: Implications from Initial Results

Mars Science Laboratory has made measurements that contribute to our assessment of habitability potential at Gale Crater. Campaign organization into a consistent set of measurable parameters allows us to rank the relative habitability potential of sites we study, ultimately laying a foundation for a global context inclusive of past and future Mars mission observations. Chemical, physical, geological and geographic attributes shape environments. Isolated measurements of these factors may be insufficient to deem an environment habitable, but the sum of measurements can help predict locations with greater or lesser habitability potential. Metrics for habitability assessment based on field work at sites sharing features analogous to Mars have previously been suggested. Grouping these metrics helps us to develop an index for their application to habitability assessment. The index is comprised of the weighted values for four groups of parameters, the habitability threshold for each is to be determined

Proviral Quasispecies Diversity Is Not Associated With Virologic Breakthrough or CD4+ T Cell Loss in HIV-1 Elite Controllers

Elite controllers (EC) are able to control HIV-1 replication to extremely low levels (<50 HIV-1 RNA copies/mL) in the absence of antiretroviral therapy. However, some EC experience CD4+ T cell loss and/or lose their ability to control HIV-1 over the course of infection. High levels of HIV-1 env proviral diversity, activated T cells and proinflammatory cytokines were pointed out as relevant biomarkers for detection of EC at risk of virologic/immunologic progression. The aim of this study was to assess the importance of proviral diversity as a prognostic marker of virologic and/or immunologic progression in EC. To this end, we analyzed plasma viremia, total HIV DNA levels, T cells dynamics, and activation/inflammatory biomarkers in EC with low (ECLD = 4) and high (ECHD = 6) HIV-1 env diversity. None of ECLD and ECHD subjects displayed evidence of immunologic progression (decrease in absolute and percentage of CD4+ T cells) and only one ECHD subject presented virologic progression (≥2 consecutive viral loads measurements above the detection limit) 2–5 years after determination of proviral env diversity. Despite differences in proviral genetic diversity, the ECLD and ECHD subgroups displayed comparable levels of total cell-associated HIV DNA, activated CD8+ T (CD38+HLA-DR+) cells and plasmatic inflammatory biomarkers (IP-10, IL-18, RANTES, PDGF-AA, and CTACK). These results indicate that the genetic diversity of the HIV-1 proviral reservoir is not a surrogate marker of residual viral replication, immune activation or inflammation, nor an accurate biomarker for the prediction of virologic breakthrough or CD4+ T cells loss in EC

Evaluation of ACCMIP Outgoing Longwave Radiation from Tropospheric Ozone Using TES Satellite Observations.

We use simultaneous observations of tropospheric ozone and outgoing longwave radiation (OLR) sensitivity to tropospheric ozone from the Tropospheric Emission Spectrometer (TES) to evaluate model tropospheric ozone and its effect on OLR simulated by a suite of chemistry-climate models that participated in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The ensemble mean of ACCMIP models show a persistent but modest tropospheric ozone low bias (5-20 ppb) in the Southern Hemisphere (SH) and modest high bias (5-10 ppb) in the Northern Hemisphere (NH) relative to TES ozone for 2005-2010. These ozone biases have a significant impact on the OLR. Using TES instantaneous radiative kernels (IRK), we show that the ACCMIP ensemble mean tropospheric ozone low bias leads up to 120mW/ sq. m OLR high bias locally but zonally compensating errors reduce the global OLR high bias to 39+/- 41mW/ sq. m relative to TES data. We show that there is a correlation (Sq. R = 0.59) between the magnitude of the ACCMIP OLR bias and the deviation of the ACCMIP preindustrial to present day (1750-2010) ozone radiative forcing (RF) from the ensemble ozone RF mean. However, this correlation is driven primarily by models whose absolute OLR bias from tropospheric ozone exceeds 100mW/ sq. m. Removing these models leads to a mean ozone radiative forcing of 394+/- 42mW/ sq. m. The mean is about the same and the standard deviation is about 30% lower than an ensemble ozone RF of 384 +/- 60mW/ sq. m derived from 14 of the 16 ACCMIP models reported in a companion ACCMIP study. These results point towards a profitable direction of combining satellite observations and chemistry-climate model simulations to reduce uncertainty in ozone radiative forcing