2,043 research outputs found

    On the Habitat and Isolation of Gymnocharacinus-Bergi (Osteichthyes, Characidae)

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    Fil: Menni, Roberto Carlos. División Zoología Vertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Gómez, Sergio E.. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

    Cauchy-characteristic Evolution of Einstein-Klein-Gordon Systems

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    A Cauchy-characteristic initial value problem for the Einstein-Klein-Gordon system with spherical symmetry is presented. Initial data are specified on the union of a space-like and null hypersurface. The development of the data is obtained with the combination of a constrained Cauchy evolution in the interior domain and a characteristic evolution in the exterior, asymptotically flat region. The matching interface between the space-like and characteristic foliations is constructed by imposing continuity conditions on metric, extrinsic curvature and scalar field variables, ensuring smoothness across the matching surface. The accuracy of the method is established for all ranges of M/RM/R, most notably, with a detailed comparison of invariant observables against reference solutions obtained with a calibrated, global, null algorithm.Comment: Submitted to Phys. Rev. D, 16 pages, revtex, 7 figures available at http://nr.astro.psu.edu:8080/preprints.htm

    Los registros más australes de Dromiciops gliroides: extendiendo su distribución más allá del bosque lluvioso valdiviano

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    The geographic range of a species is often limited by sampling approaches, underestimating the actual distribution. This is likely the case of Dromiciops gliroides (Microbiotheria), an endemic marsupial from southern South America. We used camera-traps to record D. gliroides for the first time in Chaitén and Futaleufú (southern Chile), expanding its known distribution 100 km to the south. Climate and forest composition in this area differs from the typical Valdivian rainforest. Activity assessments show a narrow activity patterns compared to northern populations.El rango geográfico de una especie usualmente está limitado por el muestreo, subestimando su distribución. Este sería el caso de Dromiciops gliroides (Microbiotheria), un marsupial endémico de Sudamérica austral. Usamos cámaras-trampa para registrar a D. gliroides por primera vez en Chaitén y Futaleufú (al sur de Chile), expandiendo su distribución 100 km al sur. El clima y la composición del bosque de esta área difieren del bosque valdiviano. Los patrones de actividad encontrados son más estrechos que los de las poblaciones más al norte

    Einstein boundary conditions for the 3+1 Einstein equations

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    In the 3+1 framework of the Einstein equations for the case of vanishing shift vector and arbitrary lapse, we calculate explicitly the four boundary equations arising from the vanishing of the projection of the Einstein tensor along the normal to the boundary surface of the initial-boundary value problem. Such conditions take the form of evolution equations along (as opposed to across) the boundary for certain components of the extrinsic curvature and for certain space-derivatives of the intrinsic metric. We argue that, in general, such boundary conditions do not follow necessarily from the evolution equations and the initial data, but need to be imposed on the boundary values of the fundamental variables. Using the Einstein-Christoffel formulation, which is strongly hyperbolic, we show how three of the boundary equations should be used to prescribe the values of some incoming characteristic fields. Additionally, we show that the fourth one imposes conditions on some outgoing fields.Comment: Revtex 4, 6 pages, text and references added, typos corrected, to appear in Phys. Rev.

    High-powered Gravitational News

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    We describe the computation of the Bondi news for gravitational radiation. We have implemented a computer code for this problem. We discuss the theory behind it as well as the results of validation tests. Our approach uses the compactified null cone formalism, with the computational domain extending to future null infinity and with a worldtube as inner boundary. We calculate the appropriate full Einstein equations in computational eth form in (a) the interior of the computational domain and (b) on the inner boundary. At future null infinity, we transform the computed data into standard Bondi coordinates and so are able to express the news in terms of its standard N+N_{+} and N×N_{\times} polarization components. The resulting code is stable and second-order convergent. It runs successfully even in the highly nonlinear case, and has been tested with the news as high as 400, which represents a gravitational radiation power of about 1013M/sec10^{13}M_{\odot}/sec.Comment: 24 pages, 4 figures. To appear in Phys. Rev.

    Non-Linear Models for Growth, Development, and Posture of L-33 White Leghorn Hens, according to Economic Indicators

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    The Zootechnical Factors established by the main indicators of bioeconomic behavior were determined for the pro-ductive-commercial cycle of L-33 White Leghorn hens in the province of Ciego de Ávila, Cuba. A number of 55 cycles were analyzed for validation of mathematical models between 2002 and 2014; other 18 cycles were studied between 2014 and 2016. Descriptive statistics, generalized mixed models (GLIMMIX), and five-function modelling were used. SAS 9.3 for Windows was also used. The productive cycles were similar to the standard set up for the breed and line in Cuba. Laying was 293 eggs/poultry, with a conversion of 1.40 feed kg/10 eggs, and a cost of $ 0.36 CUP an egg. The starting sheds and year had effects on live weight, tarsus length, uniformity, and daily weight gain up to 175 days. Sexual maturity, conversion, egg production, egg cost, and net income were influenced by farm, whereas each farm´s starting shed and the years, had negative effects on most biological indicators. Low, but significant effects of combined climate variables were observed in the bioeconomic indicators. The Gompertz´s model for growth, and Mc Nally´s for laying, were the best predicting tools for production. Along with GLIMMIX, they will contribute with suitable criteria for better decision making to increase egg production

    Mode coupling in the nonlinear response of black holes

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    We study the properties of the outgoing gravitational wave produced when a non-spinning black hole is excited by an ingoing gravitational wave. Simulations using a numerical code for solving Einstein's equations allow the study to be extended from the linearized approximation, where the system is treated as a perturbed Schwarzschild black hole, to the fully nonlinear regime. Several nonlinear features are found which bear importance to the data analysis of gravitational waves. When compared to the results obtained in the linearized approximation, we observe large phase shifts, a stronger than linear generation of gravitational wave output and considerable generation of radiation in polarization states which are not found in the linearized approximation. In terms of a spherical harmonic decomposition, the nonlinear properties of the harmonic amplitudes have simple scaling properties which offer an economical way to catalog the details of the waves produced in such black hole processes.Comment: 17 pages, 20 figures, abstract and introduction re-writte

    The close limit from a null point of view: the advanced solution

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    We present a characteristic algorithm for computing the perturbation of a Schwarzschild spacetime by means of solving the Teukolsky equation. We implement the algorithm as a characteristic evolution code and apply it to compute the advanced solution to a black hole collision in the close approximation. The code successfully tracks the initial burst and quasinormal decay of a black hole perturbation through 10 orders of magnitude and tracks the final power law decay through an additional 6 orders of magnitude. Determination of the advanced solution, in which ingoing radiation is absorbed by the black hole but no outgoing radiation is emitted, is the first stage of a two stage approach to determining the retarded solution, which provides the close approximation waveform with the physically appropriate boundary condition of no ingoing radiation.Comment: Revised version, published in Phys. Rev. D, 34 pages, 13 figures, RevTe

    Sensitivity of tumor cells towards CIGB-300 anticancer peptide relies on its nucleolar localization

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    CIGB-300 is a novel anticancer peptide that impairs the casein kinase 2-mediated phosphorylation by direct binding to the conserved phosphoacceptor site on their substrates. Previous findings indicated that CIGB-300 inhibits tumor cell proliferation in vitro and induces tumor growth delay in vivo in cancer animal models. Interestingly, we had previously demonstrated that the putative oncogene B23/nucleophosmin (NPM) is the major intracellular target for CIGB-300 in a sensitive human lung cancer cell line. However, the ability of this peptide to target B23/NPM in cancer cells with differential CIGB-300 response phenotype remained to be determined. Interestingly, in this work, we evidenced that CIGB-300's antiproliferative activity on tumor cells strongly correlates with its nucleolar localization, the main subcellular localization of the previously identified B23/NPM target. Likewise, using CIGB-300 equipotent doses (concentration that inhibits 50% of proliferation), we demonstrated that this peptide interacts and inhibits B23/NPM phosphorylation in different cancer cell lines as evidenced by in vivo pull-down and metabolic labeling experiments. Moreover, such inhibition was followed by a fast apoptosis on CIGB-300-treated cells and also an impairment of cell cycle progression mainly after 5 h of treatment. Altogether, our data not only validates B23/NPM as a main target for CIGB-300 in cancer cells but also provides the first experimental clues to explain their differential antiproliferative response. Importantly, our findings suggest that further improvements to this cell penetrating peptide-based drug should entail its more efficient intracellular delivery at such subcellular localization.Fil: Perera, Yasser. Centro de Ingeniería Genética y Biotecnología; CubaFil: Costales, Heydi C.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Diaz, Yakelin. Centro de Ingeniería Genética y Biotecnología; CubaFil: Reyes, Osvaldo. Centro de Ingeniería Genética y Biotecnología; CubaFil: Farina, Hernán Gabriel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mendez, Lissandra. Centro de Ingeniería Genética y Biotecnología; CubaFil: Gómez, Roberto E.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Acevedo, Boris E.. Centro de Ingeniería Genética y Biotecnología; CubaFil: Gomez, Daniel Eduardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Daniel Fernando. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Oncología Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Perea, Silvio E.. Centro de Ingeniería Genética y Biotecnología; Cub

    High Temperature Pulsed and DC Performance of AlInN/GaN HEMTs

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    The AlGaN/GaN high-electron mobility transistors (HEMTs) have been considered as promising candidates for the next generation of high temperature, high frequency, high-power devices. The potential of GaN-based HEMTs may be improved using an AlInN barrier because of its better lattice match to GaN, resulting in higher sheet carrier densities without piezoelectric polarization [1]. This work has been focused on the study of AlInN HEMTs pulse and DC mode characterization at high temperature
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