992 resultados para Physics, Astrophysics


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Results of relativistic (Dirac-Slater and Dirac-Fock) and nonrelativistic (Hartree-Fock-Slater) atomic and molecular calculations have been compared for the group 5 elements Nb, Ta, and Ha and their compounds MCl_5, to elucidate the influence of relativistic effects on their properties especially in going from the 5d element Ta to the 6d element Ha. The analysis of the radial distribution of the valence electrons of the metals for electronic configurations obtained as a result of the molecular calculations and their overlap with ligands show opposite trends in behavior for ns_1/2, np_l/2, and (n -1 )d_5/2 orbitals for Ta and Ha in the relativistic and nonrelativistic cases. Relativistic contraction and energetic stabilization of the ns_1/2 and np_l/2 wave functions and expansion and destabilization of the (n-1)d_5/2 orbitals make hahnium pentahalide more covalent than tantalum pentahalide and increase the bond strength. The nonrelativistic treatment of the wave functions results in an increase in ionicity of the MCl_5 molecules in going from Nb to Ha making element Ha an analog of V. Different trends for the relativistic and nonrelativistic cases are also found for ionization potentials, electronic affinities, and energies of charge-transfer transitions as well as the stability of the maximum oxidation state.

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We have simulated the behavior of several artificial flies, interacting visually with each other. Each fly is described by a simple tracking system (Poggio and Reichardt, 1973; Land and Collett, 1974) which summarizes behavioral experiments in which individual flies fixate a target. Our main finding is that the interaction of theses implemodules gives rise to a variety of relatively complex behaviors. In particular, we observe a swarm-like behavior of a group of many artificial flies for certain reasonable ranges of our tracking system parameters.

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Seleccionado en la convocatoria: Licencias por estudios destinadas a funcionarios docentes no universitarios, Gobierno de Aragón 2009-10

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Lecture notes for a course on methods of mathematical physics.

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An introduction to high quality information resources and databases in Physics and related disciplines. Refers to resources of information and methods of searching them.

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A video made by physics for the AS/A Level Science & Art Competition

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A video made by physics for the AS/A Level Science & Art Competition

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Logo for the school of Physics and Astronomy in Inkscape SVG, PDF and high-resolution PNG format

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Abstract submission form. More information available on conference website.

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resumen literal de la revista

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Introduce los diferentes aspectos de la física elemental. Incluye secciones sobre la electricidad, sonido, luz, color, magnetismo, el calor, el aire y la óptica con xperimentos sencillos, puzzles y juegos para reforzar y animar el aprendizaje teórico y el trabajo escolar.

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Obra de referencia para los estudiantes del General Certificate of Secundary Education (GCSE). Está organizada en secciones temáticas que abarcan todos los aspectos del currículo de física. Los conceptos clave y las ideas básicas se explican con un texto sencillo completado con imágenes y diagramas. Incluye una sección de gráficos, tablas y conversiones. Tiene glosario, índice y, además, enlaces a sitios web educativos para ampliar el aprendizaje de esta materia.