911 resultados para quasars: emission lines


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During recent years, the theory of differential inequalities has been extensively used to discuss singular perturbation problems and method of lines to partial differential equations. The present thesis deals with some differential inequality theorems and their applications to singularly perturbed initial value problems, boundary value problems for ordinary differential equations in Banach space and initial boundary value problems for parabolic differential equations. The method of lines to parabolic and elliptic differential equations are also dealt The thesis is organised into nine chapters

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Two-sided flux decoration experiments indicate that threading dislocation lines (TDLs), which cross the entire film, are sometimes trapped in metastable states. We calculate the elastic energy associated with the meanderings of a TDL. The TDL behaves as an anisotropic and dispersive string with thermal fluctuations largely along its Burgers vector. These fluctuations also modify the structure factor of the vortex solid. Both effects can, in principle, be used to estimate the elastic moduli of the material.

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Developments in laser technology over the past few years have made it possible to do experiments with focused intensities of IO"-102' Wcm'z. Short-pulse high-intensity lasers are able to accelerate protons and heavier ions to multi-MeV energies during their interaction with solid targets, gas jets and clusters. When such a laser radiation is focused at the intensity above 10” Wcm'2, local electric field strength will be almost equivalent to that within an atom. Hence, new nonlinear optical phenomena will be expected in the field of light matter interaction. Most of the research in the material interaction using high power lasers, especially related to plasma interaction, has been directed to the short pulse x-ray generation- Nanosecond laser interactions with solid targets also generate plasmas which emit radiation mainly in the optical region, the understanding of which is far from satisfactory. This thesis deals with a detailed study of some of the dynamical processes in plasmas generated by nanosecond and femtosecond lasers

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Development of continuous shrimp cell lines for effective investigation on shrimp viruses remains elusive with an arduous history of over 25 years. Despite presenting challenges to researchers in developing a cell line, the billion dollar aquaculture industry is under viral threat. Advances in molecular biology and various gene transfer technologies for immortalization of cells have resulted in the development of hundreds of cell lines from insects and mammals, but yet not a single cell line has been developed from shrimp and other marine invertebrates. Though improved growth and longevity of shrimp cells in vitro could be achieved by using modified growth media this did not make any leap to spontaneous transformation; probably due to the fact that shrimp cells inhibited neoplastic transformations. Oncogenic induction and immortalization are considered as the possible ways, and an exclusive medium for shrimp cell culture and an appropriate mode of transformation are crucial. In this review status of shrimp cell line development and its future orientation are discussed

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ZnO nanoflowers were synthesized by the hydrothermal process at an optimized growth temperature of 200 ◦C and a growth/reaction time of 3 h. As-prepared ZnO nanoflowers were characterized by x-ray diffraction, scanning electron microscopy, UV–visible and Raman spectroscopy. X-ray diffraction and Raman studies reveal that the as-synthesized flower-like ZnO nanostructures are highly crystalline with a hexagonal wurtzite phase preferentially oriented along the (1 0 1 1) plane. The average length (234–347 nm) and diameter (77–106 nm) of the nanorods constituting the flower-like structure are estimated using scanning electron microscopy studies. The band gap of ZnO nanoflowers is estimated as 3.23 eV, the lowering of band gap is attributed to the flower-like surface morphology and microstructure of ZnO. Room temperature photoluminescence spectrum shows a strong UV emission peak at 392 nm, with a suppressed visible emission related to the defect states, indicating the defect free formation of ZnO nanoflowers that can be potentially used for UV light-emitting devices. The suppressed Raman bands at 541 and 583 cm−1 related to defect states in ZnO confirms that the ZnO nanoflowers here obtained have a reduced presence of defects

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Relatively oxygen-free mesoporous cubic ZnS particles were synthesised via a facile solvo-hydrothermal route using a water–acetonitrile combination. Boosted UV emission at 349 nm is observed from the ZnS prepared by the solvo-hydrothermal route. The increased intensity of this UV emission is attributed to activation of whispering gallery modes of almost elliptical microstructures made of porous nanostructures.

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We have measured prompt and delayed emission spectra of electrons from foilexcited Be, B^+, and Be^2+ ions at 300 keV. On the basis of recently calculated eigenvalues we identified two lines in the prompt Be^+ spectrum as transitions from 2s^22p and 2s2p^2. The delayed Be spectrum indicates that transitions from highly excited quintet states occur. We propose radiationless deexcitation with one excited spectator electron not involved in the transition.

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Augerelectron emission from foil-excited Ne-ions (6 to 10 MeV beam energy) has been measured. The beam-foil time-of-flight technique has been applied to study electronic transitions of metastable states (delayed spectra) and to determine their lifetimes. To achieve a line identification for the complex structure observed in the prompt spectrum, the spectrum is separated into its isoelectronic parts by an Augerelectron-ion coincidence correlating the emitted electrons and the emitting projectiles of well defined final charge states q_f. Well resolved spectra were obtained and the lines could be identified using intermediate coupling Dirac-Fock multiconfiguration calculations. From the total KLL-Augerelectron transition probabilities observed in the electronion coincidence experiment for Ne (10 MeV) the amount of projectiles with one K-hole just behind a C-target can be estimated. For foil-excited Ne-projectiles in contrast to single collision results the comparison of transition intensities for individual lines with calculated transition probabilities yields a statistical population of Li- and Be-like configurations.

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This study covers an area of great importance in the research of breast cancer, related to the study of the effects of both estrogens (E2) and anti-estrogens (Tamoxifen) on chromosomes and of modulation of gene expression. Considering that breast cancer is a very heterogeneous disease and that patients respond differently to treatment, the identification of chromosomal abnormalities as well as genes responsive to 17β-estradiol (E2) and Tamoxifen (TAM) could provide the necessary framework to understand the complex effects of this hormone in target cells and could explain, at least in part, the development of cellular resistance to TAM treatment and the subsequent best therapeutic option. In this order of ideas, we determined the effects of E2 and TAM on the chromosomes and on the modulation of gene expression in four breast cancer cell lines, which represent three of the five subtypes of breast cancer known at present. The results are presented in six chapters - each one has a group of the results achieved around the cytogenetic characteristics and gene expression profiles of four cell lines and the effects of E2 and TAM incubation on those. The first chapter describes the main features of breast cancer, furthering the use and effects of E2 and TAM treatment.

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Con la finalidad de concienciar e involucrar a los estudiantes de secundaria en los problemas mundiales,la Cruz Roja Británica ha desarrollado este recurso que introduce a los alumnos en el concepto de ciudadania del mundo, y les ayuda a comprender mejor el mundo que les rodea y su lugar en él. También, conocen el significado de conceptos como la diversidad, los derechos humanos, la democracia, la justicia social y la participación activa. Las actividades propuestas exploran algunas de las dificultades y los dilemas morales a los que se enfrentan personas en situaciónes violentas y de conflicto, y estudian la respuesta a estas crisis por parte de organizaciones como la Cruz Roja y la Media Luna Roja. Se estudian, en concreto, los casos de Bosnia-Herzegovina, Ruanda e Irlanda del Norte.

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