1,078 research outputs found

    Tensor Perturbations in Quantum Cosmological Backgrounds

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    In the description of the dynamics of tensor perturbations on a homogeneous and isotropic background cosmological model, it is well known that a simple Hamiltonian can be obtained if one assumes that the background metric satisfies Einstein classical field equations. This makes it possible to analyze the quantum evolution of the perturbations since their dynamics depends only on this classical background. In this paper, we show that this simple Hamiltonian can also be obtained from the Einstein-Hilbert lagrangian without making use of any assumption about the dynamics of the background metric. In particular, it can be used in situations where the background metric is also quantized, hence providing a substantial simplification over the direct approach originally developed by Halliwell and Hawking.Comment: 24 pages, JHEP forma

    Mitochondrial dynamics and quality control in Huntington's disease

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    Huntington's disease (HD) is an inherited neurodegenerative disorder caused by polyglutamine expansion mutations in the huntingtin protein. Despite its ubiquitous distribution, expression of mutant huntingtin (mHtt) is particularly detrimental to medium spiny neurons within the striatum. Mitochondrial dysfunction has been associated with HD pathogenesis. Here we review the current evidence for mHtt-induced abnormalities in mitochondrial dynamics and quality control, with a particular focus on brain and neuronal data pertaining to striatal vulnerability. We address mHtt effects on mitochondrial biogenesis, protein import, complex assembly, fission and fusion, mitochondrial transport, and on the degradation of damaged mitochondria via autophagy (mitophagy). For an integrated perspective on potentially converging pathogenic mechanisms, we also address impaired autophagosomal transport and abnormal mHtt proteostasis in HD

    Varietal thiols in white wines from portuguese grape varieties

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    Wines from Antão Vaz, Arinto, Fernão Pires, Verdelho da Madeira and Viosinho grape cultivars, from 2009 and 2010 vintages, were studied in order to characterize the volatile thiols profile, namely 4-mercapto-4-methyl-pentan-2-one (4MMP), 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA). Volatile thiols profile of these wines was also compared to a Sauvignon blanc wine produced in Portugal. Besides sensory analysis, all wines were analyzed using GC coupled to different detectors, namely FID, FPD, MS and Olfactometry (GC-O). In all wines, GC-O analyses showed the existence of two olfactory zones related to the presence of 4MMP and 3MH. A third olfactory zone for 3MHA was only observed for the youngest wines. The wines produced from Portuguese cultivars presented aromatic intensities comparable or even higher than those obtained in the Sauvignon blanc wine. Indeed, 3MH was found in all wines and the highest amounts were observed in Antão Vaz, Arinto and Viosinho wines. In general, these findings are in agreement with those obtained by sensory analysis

    Adaptabilidade do feijão-caupi para a produtividade de grãos no Ceará.

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    O objetivo deste trabalho foi avaliar a adaptabilidade de feijão-caupi e a produtividade de grãos no Ceará

    Local character of magnetic coupling in ionic solids

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    Magnetic interactions in ionic solids are studied using parameter-free methods designed to provide accurate energy differences associated with quantum states defining the Heisenberg constant J. For a series of ionic solids including KNiF3, K2NiF4, KCuF3, K2CuF4, and high- Tc parent compound La2CuO4, the J experimental value is quantitatively reproduced. This result has fundamental implications because J values have been calculated from a finite cluster model whereas experiments refer to infinite solids. The present study permits us to firmly establish that in these wide-gap insulators, J is determined from strongly local electronic interactions involving two magnetic centers only thus providing an ab initio support to commonly used model Hamiltonians

    Lesiones faciales en niños y adolescentes víctimas de agresiones

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    Child maltreatment may occur as the intentional use of power, effective or attempted, against children under 18 years old, that results or may result in actual or potential harm. It affects a vulnerable population, causing physical and/or emotional consequences persisting throughout their lives. This study aimed to characterize episodes of child maltreatment, with focus on facial injuries, in a Brazilian city (Teresina, PI). This is a retrospective study with a quantitative approach, carried out in the database at the Institute of Forensic MedicineinTeresina, between the years 2017 and 2019. All reports of bodily injury of children from 0 to 18 years were collected and statistically analyzed (SPSS 22.0). During the period analysis, 811 reports of bodily injury were identified. There was a predominance of female victims aged between 12 and 18 years old, the involvement of men with some family relationship with the victim was highly associated. Facial injuries represented 35.8% of the whole sample and 98.6% of those found in the head and neck region (41,6% of the total). The orbital (29.0%) was the most affected site, followed by the frontal (25.9%), malar (23.4%), labial (17.6%) and cheek area (11.4%). There is a high prevalence of injuries to the head and neck region, this factemphasizes the importance of a trained professional, especially a dental surgeon, in the analysis and interpretation of these injuries during forensic examination.info:eu-repo/semantics/publishedVersio

    Adaptabilidade e estabilidade de cultivares de milho para produtividade de matéria seca e degradabilidade ruminal da silagem.

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    Estudaram-se os fatores de adaptabilidade e estabilidade de cultivares de milho para caracteres associados a qualidade da silagem, em diferentes condições ambientais. Foram avaliados dez cultivares em diferentes locais e safras agrícolas (Capinópolis, Janaúba, Lavras e Sete Lagoas, nas safras de 1997/98, 1998/99 e 1999/00, e Coronel Pacheco, nas safras de 1997/98 e 1998/99). Em todos os ambientes, o delineamento experimental utilizado foi o de blocos casualizados, com três repetições. No estádio farináceo-duro, procedeu-se à colheita das plantas da parcela, que foram cortadas e pesadas, para a determinação do peso da amostra seca ao ar. Em seguida, a matéria seca das amostras das repetições de cada cultivar foi misturada, moída e passada em peneira de 5 mm, para a avaliação de degradabilidade in situ da matéria seca, após 24 horas de incubação no rúmen de bovino. As análises de adaptabilidade e estabilidade foram realizadas utilizando os procedimentos de Eberhart e Russel (1966) e Annicchiarico (1992). Foi estimado também um índice para seleção das cultivares obtido a partir da multiplicação do carácter produção de matéria seca pela degradabilidade, utilizando as médias de cada ambiente. Observou-se que a interação cultivares e ambientes foi significativa apenas para o carácter produtividade de matéria seca. As cultivares avaliadas diferem quanto à adaptabilidade e à estabilidade de produtividade de matéria seca. A metodologia de Annicchiarico(1992) discriminou as cultivares superiores quanto à produtividade de matéria seca, em que as cultivares CO9621, DINA 1000 e DINA 657 foram as que apresentaram menor risco de baixa produtividade de matéria seca. essas cultivares forma também as que apresentaram melhor desempenho, desempenho, de acordo com o índice utilizado
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