983 research outputs found

    Gravity is controlled by cosmological constant

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    We discuss a Randall-Sundrum-type two D-braneworld model in which D-branes possess different values of the tensions from those of the charges, and derive an effective gravitational equation on the branes. As a consequence, the Einstein-Maxwell theory is realized together with the non-zero cosmological constant. Here an interesting point is that the effective gravitational constant is proportional to the cosmological constant. If the distance between two D-branes is appropriately tuned, the cosmological constant can have a consistent value with the current observations. From this result we see that, in our model, the presence of the cosmological constant is naturally explained by the presence of the effective gravitational coupling of the Maxwell field on the D-brane.Comment: 10 page

    Band-theoretical prediction of magnetic anisotropy in uranium monochalcogenides

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    Magnetic anisotropy of uranium monochalcogenides, US, USe and UTe, is studied by means of fully-relativistic spin-polarized band structure calculations within the local spin-density approximation. It is found that the size of the magnetic anisotropy is fairly large (about 10 meV/unit formula), which is comparable with experiment. This strong anisotropy is discussed in view of a pseudo-gap formation, of which crucial ingredients are the exchange splitting of U 5f states and their hybridization with chalcogen p states (f-p hybridization). An anomalous trend in the anisotropy is found in the series (US>>USe<UTe) and interpreted in terms of competition between localization of the U 5f states and the f-p hybridization. It is the spin-orbit interaction on the chalcogen p states that plays an essential role in enlarging the strength of the f-p hybridization in UTe, leading to an anomalous systematic trend in the magnetic anisotropy.Comment: 4 pages, 5 figure

    Microbiological quality of fresh local fish: coagulase-positive Staphylococci analysis.

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    The aim of this research was to evaluate and quantify the presence of Staphylococci in fresh local fish at a fish processing plant monitored by the Brazilian Federal Inspection Service (Serviço de Inspeção Federal - SIF) located in the North Region of Brazil

    Prospecção para parcerias e negócios em pesquisa, desenvolvimento e inovação.

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    O Trabalho objetiva ofertar subsídios para a gestão dos ativos tecnológicos pela Embrapa, bem como induzir a estruturação e manutenção das novas parcerias, com base no conceito de melhoria contínua de processos de apoio à inovação. Oferece um método customizado, para que o leitor possa ir se familiarizando com a prospecção dos ambientes de negócios, a segmentação de parceiros e a priorização de ativos tecnológicos, assimilando seus conceitos, métodos e ferramentas aplicáveis aos diversos níveis do planejamento para o negócio; quando se trata de captar parceiros para a atividade de pesquisa, desenvolvimento e inovação (PD&I). O texto contempla temas específicos, mas não pretende aprofundá-los. O leitor poderá fazê-lo por meio das referências apresentadas, e, para isso, citam-se documentos técnicos e referências acadêmicas

    Myeloid progenitors with PTPN11 and nonRAS pathway gene mutations are refractory to treatment with 6-mercaptopurine in juvenile myelomonocytic leukemia

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    advance online publication, February 25, 2014Juvenile myelomonocytic leukemia (JMML) is a fatal, mixed myeloproliferative and myelodysplastic disorder occurring in infancy and early childhood. Children with JMML have mutually exclusive genetic abnormalities in granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling pathways, inactivation of the NF1 or mutations in PTPN11, NRAS, KRAS and CBL. A whole-exome sequencing study, performed by Sakaguchi et al.,3 has recently demonstrated that in addition to the high frequency of RAS pathway mutations, mutations in SETBP1 and JAK3 are common recurrent secondary events, and that these events may be involved in tumor progression, and are associated with poor clinical outcomes.ArticleLEUKEMIA. 28(7):1545-1548 (2014)journal articl

    Restructuring of colloidal aggregates in shear flow: Coupling interparticle contact models with Stokesian dynamics

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    A method to couple interparticle contact models with Stokesian dynamics (SD) is introduced to simulate colloidal aggregates under flow conditions. The contact model mimics both the elastic and plastic behavior of the cohesive connections between particles within clusters. Owing to this, clusters can maintain their structures under low stress while restructuring or even breakage may occur under sufficiently high stress conditions. SD is an efficient method to deal with the long-ranged and many-body nature of hydrodynamic interactions for low Reynolds number flows. By using such a coupled model, the restructuring of colloidal aggregates under stepwise increasing shear flows was studied. Irreversible compaction occurs due to the increase of hydrodynamic stress on clusters. Results show that the greater part of the fractal clusters are compacted to rod-shaped packed structures, while the others show isotropic compaction.Comment: A simulation movie be found at http://www-levich.engr.ccny.cuny.edu/~seto/sites/colloidal_aggregates_shearflow.htm
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