4,117 research outputs found

    Eigenvalue estimates for submanifolds of warped product spaces

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    We give lower bounds for the fundamental tone of open sets in minimal submanifolds immersed into warped product spaces of type Nn×fQqN^n \times_f Q^q, where f∈C∞(N)f \in C^\infty(N). We also study the essential spectrum of these minimal submanifolds.Comment: 17 page

    The critical behavior of 3D Ising glass models: universality and scaling corrections

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    We perform high-statistics Monte Carlo simulations of three three-dimensional Ising spin-glass models: the +-J Ising model for two values of the disorder parameter p, p=1/2 and p=0.7, and the bond-diluted +-J model for bond-occupation probability p_b = 0.45. A finite-size scaling analysis of the quartic cumulants at the critical point shows conclusively that these models belong to the same universality class and allows us to estimate the scaling-correction exponent omega related to the leading irrelevant operator, omega=1.0(1). We also determine the critical exponents nu and eta. Taking into account the scaling corrections, we obtain nu=2.53(8) and eta=-0.384(9).Comment: 9 pages, published versio

    Aditivos químicos e biológicos na ensilagem de cana-de-açúcar. 1. Composição química das silagens, ingestão, digestibilidade e comportamento ingestivo.

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    Avaliou-se o efeito da inclusão de aditivos na ensilagem de cana-de-açúcar (Saccharum officinarum L.) sobre a composição químico-bromatológica das silagens, o Comportamento ingestivo, o consumo voluntário e a digestibilidade em bovinos de corte. Utilizaram-se cinco novilhos da raça Nelore providos de cânula ruminal, alocados em delineamento quadrado latino 5 × 5 e alimentados com dietas com 65% de volumoso na MS. Foram avaliadas cinco silagens (base úmida): controle - cana-de-açúcar sem aditivos; uréia - cana-de-açúcar + 0,5% uréia; benzoato - cana-de-açúcar + 0,1% de benzoato de sódio; LP - cana-de-açúcar inoculada com Lactobacillus plantarum (1 × 106 ufc/g MV); LB - cana-de-açúcar inoculada com L. buchneri (3,6 × 105 ufc/g forragem). A forragem foi armazenada em silos do tipo poço por 90 dias antes do fornecimento aos animais. A composição químico-bromatológica da cana-de-açúcar foi alterada após a ensilagem, em relação à cana-de-açúcar original, com redução no teor de carboidratos solúveis e na digestibilidade in vitro e elevação relativa nos teores de FDN e FDA. Os teores de etanol (0,30% da MS) e ácidos orgânicos (0,99% de ácido lático e 2,31% de acético) foram baixos e semelhantes entre as silagens. Os aditivos aplicados na ensilagem não promoveram alterações no consumo e na digestibilidade aparente da MS (7,2 kg/dia e 63,6%, respectivamente). O comportamento ingestivo dos animais também não foi alterado, com tempos médios de 230,6; 519,6 e 672,8 minutos/dia despendidos com ingestão de ração, ruminação e ócio, respectivamente. Os aditivos acrescidos à cana-de-açúcar promoveram pequenas alterações na maioria das variáveis avaliadas

    Osteopontin Expression during Early Cerebral Ischemia-Reperfusion in Rats: Enhanced Expression in the Right Cortex Is Suppressed by Acetaminophen

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    Osteopontin (OPN) is a pleiotropic protein implicated in various inflammatory responses including ischemia-reperfusion (I-R) injury. Two distinct forms of the protein have been identified: an extensively studied secreted form (sOPN) and a less-well-known intracellular form (iOPN). Studies have shown that increased OPN expression parallels the time course of macrophage infiltration into injured tissue, a late event in the development of cerebral infarcts. sOPN has been suggested to promote remodeling of the extracellular matrix in the brain; the function of iOPN may be to facilitate certain signal transduction processes. Here, we studied OPN expression in adult male Sprague-Dawley rats subjected to global forebrain I-R injury. We found iOPN in the cytoplasm of both cortices and the hippocampus, but unexpectedly only the right cortex exhibited a marked increase in the iOPN level after 45 min of reperfusion. Acetaminophen, a drug recently shown to decrease apoptotic incidence, caspase-9 activation, and mitochondrial dysfunction during global I-R, significantly inhibited the increase in iOPN protein in the right cortex, suggesting a role for iOPN in the response to I-R injury in the right cortex

    Influência do teor de matéria seca e do inoculante bacteriano nas características físicas e químicas da silagem de capim Tanzânia.

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    Foram avaliados os efeitos do teor de matéria seca c da adição de inoculantes bacteriano sobre a composição químico-bromatológica e perdas em silagens do capim Tanzânia. O uso do inoculante não foi efetivo em preservar a PB. Os índices de recuperação de matéria seca e as perdas de MS, na forma de efluente e gases, foram respectivamente de 90,6%; 53,7 kg (I MV e 6,4% da MS nas silagcns não-emurchecidas, 93,6%; 16,8 kg ri MV e 5,0% com adição de milheto grão e 92,2%; 3,6 kg (I MVe 6,2% naquelas emurchecidas. As densidades de massa verde/matéria seca foram 346/105,455/145 c 442/97 kg m-3 nas silagens emurchecidas, adicionadas com milheto e com umidade original, respectivamente. Como a elevação no teor de MS não alterou o índice de recuperação de MS, apesar de promover algumas modificações na composição química das silagens, a opção pelos tratamentos vai depender da ponderação de fatores que facilitem a operacionalidadc e reduzam os custos na confecção da silagem

    Measuring degree-degree association in networks

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    The Pearson correlation coefficient is commonly used for quantifying the global level of degree-degree association in complex networks. Here, we use a probabilistic representation of the underlying network structure for assessing the applicability of different association measures to heavy-tailed degree distributions. Theoretical arguments together with our numerical study indicate that Pearson's coefficient often depends on the size of networks with equal association structure, impeding a systematic comparison of real-world networks. In contrast, Kendall-Gibbons' Ï„b\tau_{b} is a considerably more robust measure of the degree-degree association

    Combination of ozone and activated carbon for Pharmaceuticals and Personal Care Products (PPCPs) removal in drinking water: influence of compounds characteristics and organic matter competition

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    The presence of Pharmaceuticals and Personal Care Products (PPCPs) in drinking water is raising concern for potential negative effects on human health. Ozonation and adsorption on activated carbon (AC) are the most promising processes for PPCPs removal among those usually present in drinking water treatment plants (DWTPs). To evaluate the performance of these processes, both individually and in combination, adsorption isotherms were determined on real matrices collected in a DWTP before and after ozonation, focusing on 10 PPCPs identified as the most critical for the analysed DWTP. AC showed higher PPCPs removals than ozonation, but the combination of the two processes was beneficial. However, the effect of ozone on adsorption depends on PPCPs reactivity with ozone. A competitive effect of organic matter on PPCPs adsorption was observed. Finally, the removal of absorbance at 254 nm is a good proxy variable for PPCPs removal

    N-(Anilinoethyl)amide Melatonergic Ligands with Improved Water Solubility and Metabolic Stability

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    The MT2-selective melatonin receptor ligand UCM765 (N-(2-((3-methoxyphenyl)(phenyl)amino)ethyl)acetamide), showed interesting sleep inducing, analgesic and anxiolytic properties in rodents, but suffers from low water solubility and modest metabolic stability. To overcome these limitations, different strategies were investigated, including modification of metabolically liable sites, introduction of hydrophilic substituents and design of more basic derivatives. Thermodynamic solubility, microsomal stability and lipophilicity of new compounds were experimentally evaluated, together with their MT1 and MT2 binding affinities. Introduction of a m-hydroxymethyl substituent on the phenyl ring of UCM765 and replacement of the replacement of the N,N-diphenyl-amino scaffold with a N-methyl-N-phenyl-amino one led to highly soluble compounds with good microsomal stability and receptor binding affinity. Docking studies into the receptor crystal structure provided a rationale for their binding affinity. Pharmacokinetic characterization in rats highlighted higher plasma concentrations for the N-methyl-N-phenyl-amino derivative, consistent with its improved microsomal stability and makes this compound worthy of consideration for further pharmacological investigation

    A KNOWLEDGE BASED APPROACH FOR RESOURCE MANAGEMENT

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    This paper discusses the applicability of a knowledge based system to resource management in the context of information centers. The Information Center Expert (ICE) system has been developed in the MIS Department of the University of Arizona to support the consultation process of information center personnel. The system determines the (software) resource requirements of the end-users and makes appropriate recommendations. ICE further aids the management of the IC software resources by keeping track of user consultations and the recommendations made. Issues of knowledge requirements, acquisition, representation and implementation of ICE are discussed. ICE is currently being tested at IBM/Endicott (New York), IBM/Tucson (Arizona) and the Center for the Management of Information at the University of Arizona. Preliminary feedback from users has confirmed the applicability of the knowledge based approach to resource management. The implications of this approach for future research are discussed
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