995 resultados para SOLAR-TYPE STARS


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The effects of type of grain (wheat vs. sorghum) and oil supplement/kg diet [0, 20g olive oil (OL), 20g safflower oil (SO), 10 g OL plus 10 g SO (OLSO)], over a 12-week period on the performance, plasma and lipoproteins lipids [cholesterol (C), triglycerides (TG), phospholipid (P)], and yolk C and fatty acids concentrations of laying hens were studied. Hens fed on the sorghum diet had significantly (P

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Development of a granular sludge with high strength, high biological activity and a narrow settling distribution is necessary for optimal operation of high-rate upflow anaerobic treatment systems. Several studies have compared granules produced from different wastewaters but these have largely been from laboratory-fed reactors or compared granules from full-scale reactors fed similar wastewater types. Though two authors have commented on the inferiority of granules produced by a protein-based feed, the properties of these granules have not been characterised. In this paper, granules from full-scale reactors treating fruit and vegetable cannery effluent, two brewery effluents and a pig abattoir (slaughterhouse) were compared in terms of basic composition, size distribution, density, settling velocity, shear strength, and EPS content. The results supported previous qualitative observations by other researchers that indicate granule properties depend more on wastewater type rather than reactor design or operating conditions such as pre-acidification level. The cannery-fed granules bad excellent shear strength, settling distribution and density. Granules from the two brewery-fed reactors had statistically the same bulk properties, which were still acceptable for upflow applications. The protein-grown granule had poor strength and settling velocity. (C) 2001 Elsevier Science Ltd. All rights reserved.

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We have isolated a cDNA clone from the honeybee brain encoding a dopamine receptor, AmDop2, which is positively coupled to adenylyl cyclase. The transmembrane domains of this receptor are 88% identical to the orthologous Drosophila D2 dopamine receptor, DmDop2, though phylogenetic analysis and sequence homology both indicate that invertebrate and vertebrate D2 receptors are quite distinct. In situ hybridization to mRNA in whole-mount preparations of honeybee brains reveals gene expression in the mushroom bodies, a primary site of associative learning. Furthermore, two anatomically distinct cell types in the mushroom bodies exhibit differential regulation of AmDop2 expression. In all nonreproductive females (worker caste) and reproductive males (drones) the receptor gene is strongly and constitutively expressed in all mushroom body interneurons with small cell bodies. In contrast, the large cell-bodied interneurons exhibit dramatic plasticity of AmDop2 gene expression. In newly emerged worker bees (cell-cleaning specialists) and newly emerged drones, no AmDop2 transcript is observed in the large interneurons whereas this transcript is abundant in these cells in the oldest worker bees (resource foragers) and older drones. Differentiation of the mushroom body interneurons into two distinct classes (i.e., plastic or nonplastic with respect to AmDop2 gene expression) indicates that this receptor contributes to the differential regulation of distinct neural circuits. Moreover, the plasticity of expression observed in the large cells implicates this receptor in the behavioral maturation of the bee.

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Early pregnancy factor (EPF) is a secreted protein, present in serum during early pregnancy and essential for maintaining viability of the embryo. It is a homologue of chaperonin 10 (Cpn10) but, unlike Cpn10, it has an extracellular role. EPF has immunosuppressive and growth regulatory properties. Previously we have reported the preparation of recombinant EPF (rEPF) and shown that treatment with rEPF will suppress clinical signs of MBP-EAE in Lewis rats and PLP-EAE in SJL/J mice. In the present study, these findings have been extended to investigate possible mechanisms involved in the action of EPF. Following treatment of mice with rEPF from the day of inoculation, there were fewer infiltrating CD3+ and CD4+ cells in the parenchyma of the spinal cord during the onset of disease and after the initial episode, compared with mice treated with vehicle. Expression of the integrins LFA-1, VLA-4 and Mac-1 and of members of the immunoglobulin superfamily of adhesion molecules ICAM-1 and VCAM-1 was suppressed in the central nervous system (CNS) following rEPF treatment. The expression of PECAM-1 was not affected. To determine if rEPF suppressed T cell activation in the periphery, the delayed-type hypersensitivity (DTH) reaction of normal BALB/c mice to trinitrochlorobenzene (TNCB) following treatment with rEPF was studied. The results showed that treatment with rEPF suppressed the DTH reaction, demonstrating the ability of EPF to downregulate the cell-mediated immune response. These results indicate that suppression of immunological mechanisms by rEPF plays a major role in the reduction of clinical signs of disease in experimental autoimmune encephalomyelitis (EAE). (C) 2003 Elsevier Science B.V. All rights reserved.

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B-type natriuretic peptide (BNP) levels increase in systolic heart failure (HF). However, the value of BNP in hypertensive patients with suspected diastolic HF (symptoms suggestive of HF but normal ejection fraction) and its relation to myocardial function in these patients is unclear. We prospectively studied 72 ambulatory hypertensive subjects (40 women, mean age 58 +/- 8 years) with exertional dyspnea and ejection fraction greater than or equal to50%. Diastolic function was evaluated with transmitral and pulmonary venous Doppler, mitral annular velocities (pulsed-wave tissue Doppler), and flow propagation velocity (color M-mode). Systolic function was assessed with strain and strain rate derived from color tissue Doppler imaging. BNP was related to myocardial function and the presence or absence of global diastolic dysfunction. By conventional Doppler criteria, 34 patients had normal left ventricular diastolic function and 38 had isolated diastolic dysfunction. BNP values were higher in patients with diastolic dysfunction (46 +/- 48 vs 20 +/- 20 pg/ml, p = 0.004) and were related independently to blood pressure, systolic strain rate, left atrial function (p < 0.01 for all), and age (p = 0.015). Patients with diastolic dysfunction and pseudonormal filling had higher BNP levels compared with impaired relaxation (89 +/- 47 vs 35 +/- 42 pg/ml, p = 0.001). However, 79% of patients with diastolic dysfunction had BNP levels within the normal range. We conclude that in ambulatory hypertensive patients with symptoms suggestive of mild HF and normal ejection fraction, BNP is related to atrial and ventricular systolic parameters, blood pressure, and age. Although elevated in the presence of diastolic dysfunction, the BNP level mostly is in the normal range and, therefore, has limited diagnostic value in stable patients with suspected diastolic HF. (C) 2003 by Excerpta Medica, Inc.

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The HERG K+ channel has very unusual kinetic behavior that includes slow activation but rapid inactivation. These features are critical for normal cardiac repolarization as well as in preventing lethal ventricular arrhythmias. Mutagenesis studies have shown that the extracellular peptide linker joining the fifth transmembrane domain to the pore helix is critical for rapid inactivation of the HERG K+ channel. This peptide linker is also considerably longer in HERG K+ channels, 40 amino acids, than in most other voltage-gated K+ channels. In this study we show that a synthetic 42-residue peptide corresponding to this linker region of the HERG K+ channel does not have defined structural elements in aqueous solution; however, it displays two well defined helical regions when in the presence of SDS micelles. The helices correspond to Trp(585)-Ile(593) and Gly(604)-Tyr(611) of the channel. The Trp(585)-Ile(593) helix has distinct hydrophilic and hydrophobic surfaces. The Gly(604)-Tyr(611) helix corresponds to an N-terminal extension of the pore helix. Electrophysiological studies of HERG currents following application of exogenous S5P peptides show that the amphipathic helix in the S5P linker interacts with the pore region of the channel in a voltage-dependent manner.

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This study reports on a block clinical trial of two types of central venous catheters (CVCs): antiseptic-impregnated catheters (AIC) and non-impregnated catheters (non-AIC), on catheter tip colonization and bacteraemia. In total, 500 catheters were inserted in 390 patients over the 18 month study period, 260 (52.0%) AIC and 240 (48.0%) non-AIC. Of these, 460 (92.0%) tips (237 AIC and 223 non-AIC) were collected. While significantly fewer AIC, 14 (5.9%), than non-AIC, 30 (13.5%), catheters were colonized (P < 0.01), there was no difference in the rates of bacteraemias in the two groups (0.8% vs. 2.7%, respectively, P = 0.16). There were 6.87 (95% CI 3.38-14.26) and 16.92 (95% CI 10.61-27.12) colonized AIC and non-AIC catheters, respectively, per 1000 catheter days, a difference that was significant (P < 0.01). However, no difference emerged between bacteraemias in AIC and non-AIC catheters per 1000 catheter days measured at 0.98 (95% CI 0.24-5.54) and 3.38 (95% CI 1.29-9.34), respectively (P = 0.10). Of the 444 CVCs that were sited in the subclavian or jugular veins and had tips collected, significantly more catheters were colonized in the jugular group, 19 (20%), compared with the subclavian group, 24 (6.9%; P less than or equal to 0.01). Overall, the low rates of colonization and bacteraemia may be explained by the population studied, the policies used and the employment of a clinical nurse dedicated to CVC management. (C) 2003 The Hospital Infection Society. Published by Elsevier Science Ltd. All rights reserved.

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A further progress has been made in defining the ionosonde deduced equator (IDE) which characterises a latitudinal transition from the northern to southern hemisphere. It is now possible to define the global IDE location as the locus of the average position between geographic and geomagnetic equators. A more complete insight to the phenomenon of the third equator (i.e. after geographic and geomagnetic equators) was made possible due to availability of ionospheric height (h'F) data from three stations positioned close to the IDE in the American and the far-east sectors. The IDE ionospheric signature (or E-type signature), detected at these stations, consists of bi-annual h'F height increases. This signature however is not consistently observed during solar cycle and at times, particularly at sunspot minimum, a weak hemispheric signature is observed (i.e. the northern or southern hemisphere signature). In general, the height increase at the IDE are considerably smaller (by a factor of 4) than at other equatorial locations, indicating that the ionosphere at the IDE location becomes less disturbed. It is suggested that the equatorial longitudinal regions which can be associated with more consistent E-type signature are located in the central Pacific and at the east coast of America, close to the intersection points of the geographic and geomagnetic equators. (C) 2003 Elsevier Ltd. All rights reserved.

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A luminosidade desponta como um dos fatores abióticos de maior importância no estabelecimento das plantas, podendo ocasionar alterações a nível fisiológico e anatômico, interferindo diretamente no desenvolvimento das mesmas e consequentemente, sua produtividade. O cacaueiro (Theobroma cacao – Malvaceae) possui grande interesse econômico devido à utilização de suas sementes para produção de manteiga de cacau e chocolate. Neste sentido, o objetivo deste trabalho foi comparar características fisiológicas e anatômicas de dois genótipos de cacaueiro (PH 16 e IPIRANGA 01), submetidos a diferentes condições de radiação solar de modo a inferir a respeito das condições de luminosidade mais favoráveis ao desenvolvimento dos mesmos. Foram realizadas análises de crescimento, teor de pigmentos, trocas gasosas e anatômicas caulinares e foliares. O delineamento experimental foi em Blocos casualizados (DBC), com 4 repetições em arranjo fatorial 2 x 5, constituído de dois genótipos e 5 níveis de luminosidade (0% - pleno sol -, 18%, 30%, 50% e 80% de sombreamento), totalizando 40 parcelas com 10 plantas cada. Os dados obtidos foram submetidos à análise de variância e regressão. Os resultados de crescimento indicam maior adaptação, de ambos os genótipos, em condições de irradiância alta a moderada. O índice de qualidade de Dickson demonstrou maior capacidade de sobrevivência em condições de campo a níveis altos de irradiância para o genótipo PH 16 e a níveis de irradiância moderada para IPIRANGA 01. Os teores de pigmentos fotossintetizantes de IPIRANGA 01 mostram-se mais elevados na condição de 30% de sombreamento, enquanto que, para PH 16 os maiores teores foram observados em 50% de sombreamento. Ambos os genótipos demonstraram altas taxas de A, Ci, E, A/E, A/Gs e A/Ci, sob elevadas irradiâncias, assim como adaptações anatômicas caulinares e foliares a maiores luminosidades, tais como, maior espessamento do limbo foliar, parênquima paliçádico, esponjoso, limbo foliar, epiderme adaxial e densidade estomática, além de maior densidade e frequência de elementos de vaso e espessura do xilema secundário. Os genótipos PH 16 e IPIRANGA 01 apresentaram uma grande plasticidade em relação aos diferentes níveis de irradiância, no entanto, constatou-se que PH 16 apresentou melhor desempenho sob condições de alta irradiância, como as obtidas nos tratamentos a pleno sol e 18% de sombreamento, enquanto que, IPIRANGA 01 mostrou-se mais adaptado sob sombreamento moderado, a 30% de sombra.

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The variation of the physical properties of four differ- ent carbon nanofibers (CNFs), based-polymer nano- composites incorporated in the same polypropylene (PP) matrix by twin-screw extrusion process was investigated. Nanocomposites fabricated with CNFs with highly graphitic outer layer revealed electrical isolation-to-conducting behaviors as function of CNF’s content. Nanocomposites fabricated with CNFs with an outer layer consisting on a disordered pyro- litically stripped layer, in contrast, revealed better mechanical performance and enhanced thermal sta- bility. Further, CNF’s incorporation into the polymer increased the thermal stability and the degree of crystallinity of the polymer, independently on the filler content and type. In addition, dispersion of the CNFs’ clusters in PP was analyzed by transmitted light opti- cal microscopy, and grayscale analysis (GSA). The results showed a correlation between the filler concentration and the variance, a parameter which measures quantitatively the dispersion, for all composites. This method indicated a value of 1.4 vol% above which large clusters of CNFs cannot be dispersed effectively and as a consequence only slight changes in mechanical performance are observed. Finally, this study establishes that for tailoring the physical properties of CNF based-polymer nanocomposites, both adequate CNFs structure and content have to be chosen.

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Cryptographic software development is a challenging eld: high performance must be achieved, while ensuring correctness and com- pliance with low-level security policies. CAO is a domain speci c language designed to assist development of cryptographic software. An important feature of this language is the design of a novel type system introducing native types such as prede ned sized vectors, matrices and bit strings, residue classes modulo an integer, nite elds and nite eld extensions, allowing for extensive static validation of source code. We present the formalisation, validation and implementation of this type system

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O presente estudo pretende avaliar o desempenho energético dos vários sistemas de preparação de águas quentes sanitárias (AQS) em edifícios de habitação. Segundo o RCCTE, decreto de lei nº 80/2006 de 4 de Abril, o recurso a sistemas de colectores solares térmicos é obrigatório sempre que haja uma exposição solar adequada. O RCCTE indica parâmetros de referência para o dimensionamento e cálculo do desempenho do sistema solar térmico. Indica nomeadamente um consumo de AQS a 60º C médio de referência de 40 l por pessoa e exige uma área mínima de captação na base de lm2 de colector padrão por ocupante convencional previsto. Existe no mercado a tendência para dimensionar o sistema para o mínimo exigido pela lei. Este relatório mostra que os parâmetros de referência do RCCTE estão desajustados à realidade portuguesa. Segundo este estudo, o consumo médio diário é o dobro do referido, resultando na redução muito significativa do desempenho energético do sistema solar, dado que existe um subdimensionamento da área de captação. Nestas condições, conclui-se que um sistema tradicional de esquentador a gás é mais eficiente que um sistema de colectores solares térmicos com apoio por efeito de Joule. Em Portugal, cerca de 35% dos sistemas solares em edifícios de habitação, utilizam esta energia de apoio. Este estudo apresenta fortes fundamentos para se rever os parâmetros de referência do RCCTE e permite concluir que o apoio por efeito de Joule, nas actuais condições, não deve ser permitido.

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Neste trabalho referiremos em particular a tecnologia do arrefecimento evaporativo com desumidificação prévia por exsicantes e far-se-á a apresentação da Unidade de Demonstração instalada no INETI (Instituto Nacional de Engenharia Tecnologia e Inovação) que faz uso dessa tecnologia que recorre a um sistema de captação de energia solar do tipo CPC (Colectores Parabólicos Compostos). Em funcionamento desde 1999, este sistema já sofreu várias alterações que serão referidas, realçando-se as que tiveram lugar mais recentemente, e serão apresentados alguns resultados entretanto obtidos. O funcionamento de todo o sistema foi acompanhado de perto, possibilitando assim, uma melhor compreensão do funcionamento do mesmo e, no caso de surgirem anomalias, actuar de imediato na tentativa de resolução. Para além da descrição dos componentes principais, modos de operação e alterações introduzidas, neste trabalho são apresentados e analisados os resultados obtidos nesta nova fase de funcionamento da UTA, após introdução de um humidificador na conduta de insuflação. Concluí-se que para períodos que antecedem e procedem o pico do Verão, esta unidade executa a sua função na perfeição apresentando valores de eficiência energética bastante favoráveis. Ao longo da estação fria, a captação de energia por parte dos colectores solares, possibilita o aquecimento dos espaços a climatizar.

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We review the stability of magnetized strange quark matter (MSQM) within the phenomenological MIT bag model, taking into account the variation of the relevant input parameters, namely, the strange quark mass, baryon density, magnetic field and bag parameter. A comparison with magnetized asymmetric quark matter in beta-equilibrium as well as with strange quark matter (SQM) is presented. We obtain that the energy per baryon for MSQM decreases as the magnetic field increases, and its minimum value at vanishing pressure is lower than the value found for SQM, which implies that MSQM is more stable than non-magnetized SQM. The mass-radius relation for magnetized strange quark stars is also obtained in this framework.