11,539 research outputs found

    Density-functionals not based on the electron gas: Local-density approximation for a Luttinger liquid

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    By shifting the reference system for the local-density approximation (LDA) from the electron gas to other model systems one obtains a new class of density functionals, which by design account for the correlations present in the chosen reference system. This strategy is illustrated by constructing an explicit LDA for the one-dimensional Hubbard model. While the traditional {\it ab initio} LDA is based on a Fermi liquid (the electron gas), this one is based on a Luttinger liquid. First applications to inhomogeneous Hubbard models, including one containing a localized impurity, are reported.Comment: 4 pages, 4 figures (final version, contains additional applications and discussion; accepted by Phys. Rev. Lett.

    Análise quantitativa de crescimento em leguminosas para adubação verde na savana de Roraima.

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    Objetivou-se descrever o crescimento, a partir da produtividade da matéria seca da parte área, do índice de área foliar (IAF), da taxa de assimilação líquida (TAL), taxa de crescimento da cultura (TCC) e da taxa de crescimento relativo (TCR), das leguminosas Crotalaria juncea L., Crotalaria spectabilis Roth, Cajanus cajan (L.) Millsp. (cv. anão Iapar 43aratã e cv. IAC favalarga), Canavalia ensiformis (L.) D.C. na savana de Roraima. Os experimentos foram conduzidos no campo experimental Água Boa da EMBRAPA/RR, em Boa Vista, durante as estações das chuvas (inverno local) dos anos 2014 e 2015. O delineamento experimental adotado foi o de blocos ao acaso, aproveitando as parcelas onde uma das estirpes padrão, BR 2003, foi utilizada como inoculante. As coletas das plantas foram realizadas, em intervalos de 7 a 21 dias, entre a data da semeadura e o florescimento, variando o número de coletas de acordo com a espécie, duração de seu ciclo e ano de cultivo. Nas avaliações dos parâmetros fisiológicos, verificou-se que as maiores taxas iniciais de crescimento foram apresentadas pelo feijão-de-porco seguido pela Crotalaria juncea e as maiores produtividades de matéria seca, na floração, foram proporcionadas pelo guandu fava-larga e Crotalaria juncea, e que as maiores áreas foliares por unidade de área (IAF) foram constatadas para a Crotalaria spectabilis

    Seasonality of net radiation in two sub-basins of Paractu by the use of modis sensor products.

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    The net radiation (Rn) represents the main source of energy for physical and chemical processes that occur in the surface-atmosphere interface, and it is used for air and soil heating, water transfer, in the form of vapor from the surface to the atmosphere, and for the metabolism of plants, especially photosynthesis. If there is no record of net radiation in certain areas, the use of information is important to help determine it. Among them we can highlight those provided by remote sensing. In this context, this work aims to estimate the net radiation, with the use of products of MODIS sensor, in the sub-basins of Entre Ribeiros creek and Preto River, located between the Brazilian states of Goiás and Minas Gerais. The SEBAL (Surface Energy Balance Algorithm for Land) was used to obtain the Rn in four different days in the period of July to October, 2007. The Rn results obtained were consistent with others cited in the literature and are important because the orbital information can help determine the Rn in areas where there are not automatic weather stations to record the net radiation

    Aceitabilidade de dez cultivares e uma linhagem de feijão-caupi (Vigna unguiculata (L.) Walp) crus e processados.

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    Este trabalho teve como objetivo avaliar sensorialmente onze cultivares de feijões-caupi (BRS Aracê; BRS Cauamé; BRS Guariba; BRS Itaim; BRS Juruá; BRS Novaera; BRS Potengi; BRS Tracuateua; BRS Tumucumaque; BRS Xiquexique e uma linhagem MNCO5?828C- 3-15) crus e processados. Os grãos crus foram apresentados em sacos de polietileno e os grãos processados tipo conserva em frascos de vidro e avaliados quanto aos atributos cor do grão, cor do anel do hilo, tamanho, formato, aceitação global e intenção de compra. Para feijões crus, os avaliadores preferiram os grãos de cor branca, pois apesar de apresentarem diferenças significativas a cultivar BRS Potengi, mostrou média que em termos práticos acarretou em maior aceitação dos provadores, confirmado pela intenção de compra. Nos feijões processados constatou-se que com relação às características da cor do grão, aceitação global e intenção de compra o tratamento BRS Tracuateua apresentou p<0,05; com relação ao formato e o tamanho as amostras significativas foram, respectivamente, BRS Aracê e BRS Juruá. No entanto, a cor do anel do hilo para as cultivares analisadas não houve diferença significativa. De acordo com os resultados obtidos pode-se verificar que os feijões crus obtiveram maior preferência dos avaliadores para os feijões de cor branca, porém, nos processados essa aceitação incluiu os grãos verdes, confirmando potencial mercado para estes grãos.CONAC 2012. Disponível em: http://www.conac2012.org/resumos/pdf/195a.pdf. Acesso em: 06 ago. 2013

    High-dimensional decoy-state quantum key distribution over 0.3 km of multicore telecommunication optical fibers

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    Multiplexing is a strategy to augment the transmission capacity of a communication system. It consists of combining multiple signals over the same data channel and it has been very successful in classical communications. However, the use of enhanced channels has only reached limited practicality in quantum communications (QC) as it requires the complex manipulation of quantum systems of higher dimensions. Considerable effort is being made towards QC using high-dimensional quantum systems encoded into the transverse momentum of single photons but, so far, no approach has been proven to be fully compatible with the existing telecommunication infrastructure. Here, we overcome such a technological challenge and demonstrate a stable and secure high-dimensional decoy-state quantum key distribution session over a 0.3 km long multicore optical fiber. The high-dimensional quantum states are defined in terms of the multiple core modes available for the photon transmission over the fiber, and the decoy-state analysis demonstrates that our technique enables a positive secret key generation rate up to 25 km of fiber propagation. Finally, we show how our results build up towards a high-dimensional quantum network composed of free-space and fiber based linksComment: Please see the complementary work arXiv:1610.01812 (2016

    Human cachexia induces changes in mitochondria, autophagy and apoptosis in the skeletal muscle

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    Cachexia is a wasting syndrome characterized by the continuous loss of skeletal muscle mass due to imbalance between protein synthesis and degradation, which is related with poor prognosis and compromised quality of life. Dysfunctional mitochondria are associated with lower muscle strength and muscle atrophy in cancer patients, yet poorly described in human cachexia. We herein investigated mitochondrial morphology, autophagy and apoptosis in the skeletal muscle of patients with gastrointestinal cancer-associated cachexia (CC), as compared with a weight-stable cancer group (WSC). CC showed prominent weight loss and increased circulating levels of serum C-reactive protein, lower body mass index and decreased circulating hemoglobin, when compared to WSC. Electron microscopy analysis revealed an increase in intermyofibrillar mitochondrial area in CC, as compared to WSC. Relative gene expression of Fission 1, a protein related to mitochondrial fission, was increased in CC, as compared to WSC. LC3 II, autophagy-related (ATG) 5 and 7 essential proteins for autophagosome formation, presented higher content in the cachectic group. Protein levels of phosphorylated p53 (Ser46), activated caspase 8 (Asp384) and 9 (Asp315) were also increased in the skeletal muscle of CC. Overall, our results demonstrate that human cancer-associated cachexia leads to exacerbated muscle-stress response that may culminate in muscle loss, which is in part due to disruption of mitochondrial morphology, dysfunctional autophagy and increased apoptosis. To the best of our knowledge, this is the first report showing quantitative morphological alterations in skeletal muscle mitochondria in cachectic patients

    Qualidade de frutos de híbridos de mangueira gerados a partir das variedades Van Dyke, Haden e Tommy atkins

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    O objetivo deste trabalho foi avaliar a qualidade dos frutos de 18 híbridos de mangueira gerados a partir das variedades Van Dyke e Haden com Tommy Atkins, nas condições do Semiárido Brasileiro

    Qualidade e conservação pós-colheita dos frutos de acessos de mangueira Eespada ouro, Juazeiro VII e Ômega do Banco Ativo de Germoplasma da Embrapa Semiárido .

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    O presente trabalho teve por objetivo avaliar a qualidade e a conservação pós-colheita de manga dos acessos Espada Ouro, Juazeiro VII e Ômega, durante o armazenamento refrigerado, visando novas opções de cultivares para o mercado

    Qualidade e conservação pós-colheita dos frutos de acessos de mangueira H2E2, Heidi e Celebration do Banco Ativo de Germoplasma da Embrapa Semiárido.

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    O presente trabalho teve por objetivo avaliar a qualidade e a conservação pós-colheita de manga dos acessos H2E2, Heidi e Celebration, durante o armazenamento refrigerado
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