1,221 research outputs found

    Combining visible and infrared radiometry and lidar data to test simulations in clear and ice cloud conditions

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    Measurements taken during the 2003 Pacific THORPEX Observing System Test (P-TOST) by the MODIS Airborne Simulator (MAS), the Scanning High-resolution Interferometer Sounder (S-HIS) and the Cloud Physics Lidar (CPL) are compared to simulations performed with a line-by-line and multiple scattering modeling methodology (LBLMS). Formerly used for infrared hyper-spectral data analysis, LBLMS has been extended to the visible and near infrared with the inclusion of surface bi-directional reflectance properties. A number of scenes are evaluated: two clear scenes, one with nadir geometry and one cross-track encompassing sun glint, and three cloudy scenes, all with nadir geometry. <br><br> CPL data is used to estimate the particulate optical depth at 532 nm for the clear and cloudy scenes and cloud upper and lower boundaries. Cloud optical depth is retrieved from S-HIS infrared window radiances, and it agrees with CPL values, to within natural variability. MAS data are simulated convolving high resolution radiances. The paper discusses the results of the comparisons for the clear and cloudy cases. LBLMS clear simulations agree with MAS data to within 20% in the shortwave (SW) and near infrared (NIR) spectrum and within 2 K in the infrared (IR) range. It is shown that cloudy sky simulations using cloud parameters retrieved from IR radiances systematically underestimate the measured radiance in the SW and NIR by nearly 50%, although the IR retrieved optical thickness agree with same measured by CPL. <br><br> MODIS radiances measured from Terra are also compared to LBLMS simulations in cloudy conditions, using retrieved cloud optical depth and effective radius from MODIS, to understand the origin for the observed discrepancies. It is shown that the simulations agree, to within natural variability, with measurements in selected MODIS SW bands. <br><br> The impact of the assumed particles size distribution and vertical profile of ice content on results is evaluated. Sensitivity is much smaller than differences between measured and simulated radiances in the SW and NIR. <br><br> The paper dwells on a possible explanation of these contradictory results, involving the phase function of ice particles in the shortwave

    Leave-one-out prediction error of systolic arterial pressure time series under paced breathing

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    In this paper we show that different physiological states and pathological conditions may be characterized in terms of predictability of time series signals from the underlying biological system. In particular we consider systolic arterial pressure time series from healthy subjects and Chronic Heart Failure patients, undergoing paced respiration. We model time series by the regularized least squares approach and quantify predictability by the leave-one-out error. We find that the entrainment mechanism connected to paced breath, that renders the arterial blood pressure signal more regular, thus more predictable, is less effective in patients, and this effect correlates with the seriousness of the heart failure. The leave-one-out error separates controls from patients and, when all orders of nonlinearity are taken into account, alive patients from patients for which cardiac death occurred

    Interação de genótipos de Pinus taeda L. com locais no sul-sudeste do Brasil.

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    A importância da resposta relativa diferenciada de progênies e de árvores por locais em Pinus taeda L. na perda de potencial genético pela seleção foi estudada no caráter volume de madeira total do tronco, em 46 progênies de meio-irmãos, em quatro locais no sul-sudeste do Brasil. As progê-nies foram dispostas em nove parcelas lineares, com seis plantas espaçadas em 3 m x 2 m. As análises de variância foram realizadas por local, em conjunto e por locais, dois a dois. As componentes de vari-ância foram estimadas a partir dessas análises e por máxima verossimilhança restrita (REML). Nesse método, foram ajustados modelos estatísticos mistos para a interação das progênies x locais e preditos os valores genéticos aditivos (VG's) pela “melhor predição linear não viciada” (BLUP). A interação foi significativa nas análises de variância conjunta e por locais, dois a dois. O ajuste de modelos mis-tos também foi significativo pelo teste da razão de verossimilhança. A perda do potencial genético na seleção de progênies com base nas estimativas por REML foi de 3,2%. Na seleção de genitores, a per-da na resposta média, pela seleção por VG’s médios, em vez de VG’s por locais, foi de 2,3%. Na sele-ção de árvores para pomares de sementes por mudas não ocorreu redução na resposta média. Para po-mar clonal de dez árvores, a interação superestimou a resposta média esperada em 2%. Nessa ação de melhoramento, a seleção pelo VG médio incrementou a resposta média em 3%. Esse valor foi conside-rado, como a perda de potencial genético, pela não seleção pelo VG médio, quando a interação progê-nies x locais e/ou, o ajuste de modelos são significativos. Sugere-se, o uso do valor genético médio na seleção individual, para maximizar a resposta média esperada

    Computational Fluid Dynamics of Reacting Flows at Surfaces: Methodologies and Applications

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    This review presents the numerical algorithms and speed-up strategies developed to couple continuum macroscopic simulations and detailed microkinetic models in the context of multiscale approaches to chemical reactions engineering. CFD simulations and hierarchical approaches are discussed both for fixed and fluidized systems. The foundations of the methodologies are reviewed together with specific examples to show the applicability of the methods. These concepts play a pivotal role to enable the first-principles multiscale approach to systems of technological relevance

    Efeitos do sítio e de cenários de custos e preços na análise de regimes de manejo com e sem desbaste em Pinus taeda L.

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    Foram analisados regimes de manejo sem desbaste e com um desbaste em Pinus taeda, com o objetivo de produzir madeira para celulose e laminação. Para tanto, foi utilizado um simulador de crescimento e produção denominado PISAPRO, implementado a partir de dados de parcelas permanentes de toda a área da Empresa PISA Florestal S.A.. Os cenários de produção simulados em regimes sem desbaste foram: (a) densidades de plantio: 2.000, 1.667, 1.333 e 1.111 plantas por hectare e (b) idades de rotação: 9 a 20 anos. Em regimes com um desbaste, foram simulados os seguintes cenários: (a) densidades de plantio: 2.000, 1.667, 1.333 e 1.111 plantas por hectare; (b) idades do desbaste: 6, 9 e 12 anos; (c) densidades após o desbaste: 400, 700 e 1.000 árvores por hectare e (d) idades de rotação: 15, 18 e 21 anos. Cada regime foi simulado em cinco classes de sítio. Os cenários de análise econômica, simulados com o uso do Software INVEST, foram: (a) taxas de desconto: 6% e 8% ao ano; (b) custos de colheita: em terreno plano e em terreno acidentado; (c) distâncias de transporte da madeira para celulose e laminação: 15 km, 50 km e 85 km e (d) preços da madeira para laminação: valor de mercado e acréscimo de 20%. A classe de produtividade e os parâmetros de custos e preços adotados provocaram influência significativa sobre o regime de manejo que produz o máximo Valor Esperado da Terra (VET). A distância de transporte da madeira para celulose exerceu efeito maior sobre a rentabilidade, em relação à distância de transporte da madeira para laminação. O melhor regime com desbaste apresentou rentabilidade superior em relação ao melhor regime sem desbaste, em todos os cenários de custos e preços simulados. Essa superioridade foi mais acentuada nos melhores sítios e nas melhores condições de custos e preços consideradas na análise de sensibilidade

    UV Raman lidar measurements of relative humidity for the characterization of cirrus cloud microphysical properties

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    Abstract. Raman lidar measurements performed in Potenza by the Raman lidar system BASIL in the presence of cirrus clouds are discussed. Measurements were performed on 6 September 2004 in the frame of the Italian phase of the EAQUATE Experiment. The major feature of BASIL is represented by its capability to perform high-resolution and accurate measurements of atmospheric temperature and water vapour, and consequently relative humidity, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV. BASIL is also capable to provide measurements of the particle backscatter and extinction coefficient, and consequently lidar ratio (at the time of these measurements, only at one wavelength), which are fundamental to infer geometrical and microphysical properties of clouds. A case study is discussed in order to assess the capability of Raman lidars to measure humidity in presence of cirrus clouds, both below and inside the cloud. While air inside the cloud layers is observed to be always under-saturated with respect to water, both ice super-saturation and under-saturation conditions are found inside these clouds. Upper tropospheric moistening is observed below the lower cloud layer. The synergic use of the data derived from the ground based Raman Lidar and of spectral radiances measured by the NAST-I Airborne Spectrometer allows the determination of the temporal evolution of the atmospheric cooling/heating rates due to the presence of the cirrus cloud. Lidar measurements beneath the cirrus cloud layer have been interpreted using a 1-D cirrus cloud model with explicit microphysics. The 1-D simulations indicate that sedimentation-moistening has contributed significantly to the moist anomaly, but other mechanisms are also contributing. This result supports the hypothesis that the observed mid-tropospheric humidification is a real feature which is strongly influenced by the sublimation of precipitating ice crystals. Results illustrated in this study demonstrate that Raman lidars, like the one used in this study, can resolve the spatial and temporal scales required for the study of cirrus cloud microphysical processes and appear sensitive enough to reveal and quantify upper tropospheric humidification associated with cirrus cloud sublimation

    Rôle d'un intermédiaire lipidique dans le transfert du mannose à des accepteurs glycoprotéiques endogènes chez Aspergillus niger

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    AbstractPrevious studies from this laboratory have shown that a particulate preparation from Aspergillus niger catalyses the incorporation of mannose, from GDP-mannose, into a lipid fraction which has been identified as polyprenyl phosphate mannose (PPM). The results of kinetic studies presented in this communication suggest that PPM serves as an intermediate in the ensymatic transfer of mannosyl unit from GDP-mannose to endogenous glycoproteins. β-elimination or Pronase treatment and subsequent dialysis result respectively in 70% or 90% release of radioactivity. The absence of passive penetration of GDP-mannose across microsome membranes and the inhibitory effect of palmityl-CoA on mannose transfer are in good agreement with the involvement of PPM in the transport of mannose across membranes

    Batchsize and topological criteria: a combined approach to safely optimize hazardous polymerization processes

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    Small and medium chemical enterprises are widely diffused in Italy. Particularly, they operate batch and semi-batch processes working on job orders and making a massive use of multipurpose reactors having an Emergency Relief System (ERS) already installed. A batchsize approach is a method focused on finding the reactor fill level that can lead to a single phase vapor flow whether an external fire occurs, so that the installed ERS can protect the reactor from overpressures. In this work, such an approach has been revised, by choosing a runaway reaction as design incidental scenario, and integrated with a suitable optimization procedure based on topological criteria. The new batchsize approach allows for computing a reactor fill level which is much more reasonable for industrial applications with respect to that one predicted by the older method, while the topological approach permits to identify the minimum dosing time capable of guaranteeing both reactor safety and high productivity. Theoretical results have been experimentally validated using data obtained by reaction calorimetry experiments, carried out in an isoperibolic RC1 equipment (1 L, Mettler Toledo), implementing the relevant case study of the solution homopolymerization of butyl acrylate
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