705 research outputs found

    Captura-recaptura: um estudo de simulação para avaliar a performance de estimadores do tipo Lincoln-Petersen

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    Os modelos de captura-recaptura têm sido amplamente utilizados para estimar a dimensão de populações naturais. A forma mais simples de um estudo de captura-recaptura consiste em tirar, primeiro, uma amostra de indivíduos de dimens ão n1. Estes indivíduos são marcados e identi cados de forma única e devolvidos à área de estudo para que se integrem novamente à população de interesse. Posteriormente, uma amostra aleatória de dimensão n2 é também tirada da população. Na segunda amostra encontramos que n11 dos n2 animais capturados foram previamente marcados. Uma simples relação entre as proporções dos indivíduos marcados na popula ção e os indivíduos marcados na segunda amostra gera um estimador do tamanho da população de interesse. O estimador resultante é conhecido como o estimador de Lincoln-Petersen. Vários modelos probabilísticos associados a este estimador formam as bases para a teoria de amostragem em populações animais conhecida como capturarecaptura. Neste trabalho, apresentam-se e comparam-se as performances de quatro estimadores do tipo de Lincoln-Petersen propostos na literatura

    Parálisis del plexo braquial por pseudoaneurisma de la arteria axilar tras luxación de hombro

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    Las lesiones del plexo braquial y de las arterias subclavia y axilar son complicaciones poco frecuentes, pero importantes, de los traumatismos dé la cintura escapular. Las lesiones neurovasculares son más frecuentes en heridas penetrantes, pero son raras en traumatismos cerrados. Cuando la sintomatología neurológica se desarrolla insidiosamente, días o semanas después del traumatismo, hay que pensar en una lesión vascular. Presentamos un caso de parálisis del plexo braquial tardía, en un paciente varón de 39 años, que sufrió una luxación gleno-humeral anterior diez días antes. La angiografía mostró un pseudoaneurisma de la arteria axilar y el electromiograma confirmó la parálisis del plexo braquial. El tratamiento consistió en la reparación del defecto vascular. Al año de la intervención la evolución tanto clínica, como electrofisiológica fue satisfactoria, aunque no completa.Injuries to the brachial plexus and subclavian and axillary arteries are uncommon and serious complications of shoulder girdle trauma, due to the close anatomical relationship between them. Neurovascular injuries are most frequent in penetrant lesions, but are are after a closed trauma. When neurological symptoms develop insidiously, some days to weeks after trauma, that should lead to the suspicion of a vascular injury. We report a delayed brachial plexus paralysis in a 39 years old male, who sustained an anterior dislocation of the shoulder ten days before. The DIVAS showed a pseudoaneurysm of the axillary artery and the EMG confirmed the brachial plexus palsy. Treatment consisted in surgical release repair of the vascular defect. One year follow-up show good clinical result

    Numerical study of pattern formation following a convective instability in non-Boussinesq fluids

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    We present a numerical study of a model of pattern formation following a convective instability in a non-Boussinesq fluid. It is shown that many of the features observed in convection experiments conducted on CO2CO_{2} gas can be reproduced by using a generalized two-dimensional Swift-Hohenberg equation. The formation of hexagonal patterns, rolls and spirals is studied, as well as the transitions and competition among them. We also study nucleation and growth of hexagonal patterns and find that the front velocity in this two dimensional model is consistent with the prediction of marginal stability theory for one dimensional fronts.Comment: 9 pages, report FSU-SCRI-92-6

    Limits on excited tau leptons masses from leptonic tau decays

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    We study the effects induced by excited leptons on the leptonic tau decay at one loop level. Using a general effective lagrangian approach to describe the couplings of the excited leptons, we compute their contributions to the leptonic decays and use the current experimental values of the branching ratios to put limits on the mass of excited states and the substructure scale.Comment: 10 pages, 6 figures, to be published in Phys. Rev.

    Revisión crítica de la estimulación subtalámica en la enfermedad de Parkinson

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    The authors critically review subthalamic nucleus (STN) stimulation for Parkinson's disease (PD) at long follow-up (3-5 years). Subthalamic stimulation induce a significant improvement during the "off" medication in the assessment motor score UPDRS (Unified Parkinson Disease Rating Scale) 3-5 years after surgery. Results show that the benefits obtained in tremor, rigidity, bradykinesia, dyskinesias induced by medication and levodopa reduction are significantly maintained during long term. The improvement in other clinical signs as gait and postural stability at long follow-up are not maintained comparing with the benefits obtained one year after surgery. A high percentage of patients show a cognitive disturbance during the follow-up period that may be correlated with the disease progression. The conclusion is that bilateral STN stimulation is an effective treatment for PD patients at long term but it should be considered earlier in the course of P

    Idosos institucionalizados no concelho de Viseu: Hábitos alimentares

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    O envelhecimento da população, bem como a alteração da dinâmica da família, têm contribuído diretamente para o aumento do número de idosos institucionalizados. A incidência da desnutrição alcança níveis elevados nestes idosos, sendo essencial o seu diagnóstico precoce para a melhoria da sua qualidade de vida. Constitui objetivo primordial do estudo a avaliação do estado nutricional de idosos institucionalizados no concelho de Viseu, Portugal. A amostra (n=120) é constituída por idosos de ambos os sexos, institucionalizados, com idade igual ou superior a 65 anos, com capacidade para se colocar de pé, sem demência e que não sejam portadores de patologia passível de afetar a digestão, absorção ou utilização dos nutrientes. A avaliação do estado nutricional é determinada tendo em conta parâmetros antropométricos e dietéticos, através da avaliação da ingestão alimentar (registo de 3 dias) e Mini Nutricional Assessment (MNA). Os questionários aplicados estão validados para a população portuguesa idosa e foram aplicados após consentimento informado. Considerou-se um nível de confiança de 95%. A amostra estudada é maioritariamente feminina (70,0%), com uma idade média de 82,4±6,4 anos. A determinação do IMC mostrou que 12,5% dos idosos avaliados têm baixo peso (IMC 17,7±1,3); 46,7% são eutróficos (IMC 19,9±0,5); 11,7% apresentam excesso de peso (IMC 22,1±0,7), sendo 29,1% classificados como obesos (IMC 28,8±4,2). O MNA mostra que 65% dos idosos apresenta estado nutricional normal, estando sob risco de desnutrição 33,3%, verificando-se, este risco de desnutrição ser superior nos idosos ≥ 75 anos e na população feminina (3:1). A ingestão energética média por dia é significativamente inferior à recomendada (p≤0,05), sendo a ingesta de proteína e hidratos de carbono superior aos valores recomendados para a população (p≤0,05). O consumo lipídico é maioritariamente normolipídico (54,1%), devendo-se a um consumo reduzido de ácidos gordos monosaturados vs. polinsaturados.info:eu-repo/semantics/publishedVersio

    Multiple strain-induced phase transitions in LaNiO3 thin films

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    Weber, M.C. et al.Strain effects on epitaxial thin films of LaNiO3 grown on different single crystalline substrates are studied by Raman scattering and first-principles simulation. New Raman modes, not present in bulk or fully-relaxed films, appear under both compressive and tensile strains, indicating symmetry reductions. Interestingly, the Raman spectra and the underlying crystal symmetry for tensile and compressively strained films are different. Extensive mapping of LaNiO3 phase stability is addressed by simulations, showing that a variety of crystalline phases are indeed stabilized under strain which may impact the electronic orbital hierarchy. The calculated Raman frequencies reproduce the principal features of the experimental spectra, supporting the validity of the multiple strain-driven structural transitions predicted by the simulations.J.K., M.W., M.G., and J.I. acknowledge support from the National Research Fund, Luxembourg through a Pearl grant (Grant No. FNR/P12/4853155). ICMAB-CSIC authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015- 0496) and the MAT2014-56063-C2-1-R and MAT2013- 40581-P projects, and from Generalitat de Catalunya (2014 SGR 734). UB authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness, project MAT2013-41506-P and from Generalitat de Catalunya (2014 SGR 672).Peer reviewe

    Square Patterns and Quasi-patterns in Weakly Damped Faraday Waves

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    Pattern formation in parametric surface waves is studied in the limit of weak viscous dissipation. A set of quasi-potential equations (QPEs) is introduced that admits a closed representation in terms of surface variables alone. A multiscale expansion of the QPEs reveals the importance of triad resonant interactions, and the saturating effect of the driving force leading to a gradient amplitude equation. Minimization of the associated Lyapunov function yields standing wave patterns of square symmetry for capillary waves, and hexagonal patterns and a sequence of quasi-patterns for mixed capillary-gravity waves. Numerical integration of the QPEs reveals a quasi-pattern of eight-fold symmetry in the range of parameters predicted by the multiscale expansion.Comment: RevTeX, 11 pages, 8 figure

    Aggregation of Cyclodextrins: Fundamental Issues and Applications

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    The aggregation of cyclodextrins (CD) in aqueous solution is an old, yet still vastly unexplored topic that has been studied at least since the 1980s. At that time, few authors took into consideration the possibility of formation of aggregates for the interpretation of thermodynamic and thermophysical properties of CDs in aqueous solution. The aggregates appear at quite low CD concentrations and seem to encompass only a small number of CD molecules. They also occur in water in the presence of hydrophobic or amphiphilic moieties, including surfactants, assuming a preassembled state with the hydrophobic chains threading through one or two CDs. After a long period in which it has been neglected, CD aggregation is now a hot topic and one far from gathering consensus. In this chapter, a timely and critical review on the phenomenon of CD aggregation and the respective supramolecular properties, including some computational rationales, will be presented. A comprehensive summary of CD aggregates studied to date, indicating the formation conditions, characterization techniques, and applications, is also provided

    Nutritional and Health Profile of Goat Products: Focus on Health Benefits of Goat Milk

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    Goat (Capra hircus) is one of the main sources of milk and meat products for human consumption. Goat milk differs from cow and human milk in both composition and nutritional properties. Goat milk and other goat-derived products contain several bioactive compounds that might be useful in patients suffering from a variety of chronic diseases. Several peptides, fats, and oligosaccharides present in goat’s milk can be potentially useful in cardiovascular disease, metabolic disorders, neurological degeneration, or in promoting intestinal health. They have also shown chemopreventive properties in cancer. In addition, the oligosaccharides present in goat’s milk have immunomodulatory properties, prevent adhesion of pathogenic bacteria, and have prebiotic, probifidogenic effects. Due to its potential health benefits, goat milk is particularly recommended for infants, older adults, and convalescing people. This chapter gives an overview of the biological activities of goat products and the effects of peptides, fats, and oligosaccharides present in goat milk on pathogenic bacteria, as well as their ability to regulate immunological, gastrointestinal, hormonal, and neurological responses in humans
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