997 resultados para Nonlinear structures
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A branching random motion on a line, with abrupt changes of direction, is studied. The branching mechanism, being independient of random motion, and intensities of reverses are defined by a particle's current direction. A soluton of a certain hyperbolic system of coupled non-linear equations (Kolmogorov type backward equation) have a so-called McKean representation via such processes. Commonly this system possesses traveling-wave solutions. The convergence of solutions with Heaviside terminal data to the travelling waves is discussed.This Paper realizes the McKean programme for the Kolmogorov-Petrovskii-Piskunov equation in this case. The Feynman-Kac formula plays a key role.
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Resumen en español. Resumen basado en el de la publicación
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Hipótesis: ¿la inversión es tomada en consideración por los sujetos vascófonos? ¿en qué momento su influencia es perceptible? ¿hay otros caracteres pragmáticos que ejercen una influencia en la comprensión de frases simples vascas?. ¿En qué momento las flexiones casuales comienzan a ser tomadas en consideración, y cuando son dominadas? ¿la categorización flexional de las funciones casuales es adquirida antes de la categorización posicional? ¿Las reglas de orden que han sido sacadas de experiencias efectuadas en inglés y francés, se aplican al tratamiento del vasco?, y en caso afirmativo, ¿cuál es la naturaleza de estos tratamientos?. 480 sujetos vasco parlantes entre 3 años y 11 años pertenecientes a ikastolas de Rentería y Oyarzun, y 80 adultos. Estudia la organización y evolución de los procedimientos de tratamiento relativos a las funciones casuales fundamentales de la frase simple, sin tener en cuenta los parámetros discursivos implicados. Cuestionario realizado ad hoc sobre aspectos familiares. Seis enunciados: los cinco primeros contienen dos lexemas nominales y un verbo, y el sexto contiene tres nombres y un verbo (A,B,C,D,E,F). Prueba de Chi cuadrado. Índice descriptivo de dependencia: coeficiente de Crámer. Coeficiente de contingencia. Para los lexemas nominales de los enunciados de tipo D (hija-perro-invertir), el perro es elegido tres veces más como agente que la hija. Entre la hija y el muchacho de los enunciados de tipo A, el muchacho es muchas más veces considerado como agente que la hija. De los tres lexemas animales de los enunciados F, el hombre es también interpretado más como agente que el perro y el pájaro. En los enunciados C (coche-camión-entrar-introducir), se constata que la atribución del rol depende de la interpretación transitiva o intransitiva del verbo. En Euskera la utilización apropiada de signos morfológicos casuales es muy tardía: los sujetos no se refieren a ellos antes de los 10 años y medio. Los tratamientos de tipo posicional tienen una presencia limitada pero netamente perceptible, sobre todo en el caso de los enunciados de procesos transitivo y reversible.
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Se repasan las grandes construcciones del mundo desde la antigüedad hasta la actualidad, desde las siete maravillas del mundo antiguo, castillos, palacios y puentes hasta las Torres Petronas, el Metro de Moscú, los rascacielos, los edificios actuales y futuros más extraños y los puertos espaciales.
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The morphology and reproductive structures of Mediterranean species of the genus Nemastoma J. Agardh, nom. cons. (Nemastomataceae, Nemastomatales): Nemastoma dichotomum and N. dumontioides
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Three conjugated organic molecules that span a range of polarity and valence-bond/charge transfer characteristics were studied. It was found that dispersion can be insignificant, and that adequate treatment can be achieved with frequency-dependent field-induced vibrational coordinates (FD-FICs)
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Electrical property derivative expressions are presented for the nuclear relaxation contribution to static and dynamic (infinite frequency approximation) nonlinear optical properties. For CF4 and SF6, as opposed to HF and CH4, a term that is quadratic in the vibrational anharmonicity (and not previously evaluated for any molecule) makes an important contribution to the static second vibrational hyperpolarizability of CF4 and SF6. A comparison between calculated and experimental values for the difference between the (anisotropic) Kerr effect and electric field induced second-harmonic generation shows that, at the Hartree-Fock level, the nuclear relaxation/infinite frequency approximation gives the correct trend (in the series CH4, CF4, SF6) but is of the order of 50% too small
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A general reduced dimensionality finite field nuclear relaxation method for calculating vibrational nonlinear optical properties of molecules with large contributions due to anharmonic motions is introduced. In an initial application to the umbrella (inversion) motion of NH3 it is found that difficulties associated with a conventional single well treatment are overcome and that the particular definition of the inversion coordinate is not important. Future applications are described
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The vibrational configuration interaction method used to obtain static vibrational (hyper)polarizabilities is extended to dynamic nonlinear optical properties in the infinite optical frequency approximation. Illustrative calculations are carried out on H2 O and N H3. The former molecule is weakly anharmonic while the latter contains a strongly anharmonic umbrella mode. The effect on vibrational (hyper)polarizabilities due to various truncations of the potential energy and property surfaces involved in the calculation are examined
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A variational approach for reliably calculating vibrational linear and nonlinear optical properties of molecules with large electrical and/or mechanical anharmonicity is introduced. This approach utilizes a self-consistent solution of the vibrational Schrödinger equation for the complete field-dependent potential-energy surface and, then, adds higher-level vibrational correlation corrections as desired. An initial application is made to static properties for three molecules of widely varying anharmonicity using the lowest-level vibrational correlation treatment (i.e., vibrational Møller-Plesset perturbation theory). Our results indicate when the conventional Bishop-Kirtman perturbation method can be expected to break down and when high-level vibrational correlation methods are likely to be required. Future improvements and extensions are discussed
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The level of ab initio theory which is necessary to compute reliable values for the static and dynamic (hyper)polarizabilities of three medium size π-conjugated organic nonlinear optical (NLO) molecules is investigated. With the employment of field-induced coordinates in combination with a finite field procedure, the calculations were made possible. It is stated that to obtain reasonable values for the various individual contributions to the (hyper)polarizability, it is necessary to include electron correlation. Based on the results, the convergence of the usual perturbation treatment for vibrational anharmonicity was examined
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Initial convergence of the perturbation series expansion for vibrational nonlinear optical (NLO) properties was analyzed. The zero-point vibrational average (ZPVA) was obtained through first-order in mechanical plus electrical anharmonicity. Results indicated that higher-order terms in electrical and mechanical anharmonicity can make substantial contributions to the pure vibrational polarizibility of typical NLO molecules
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The problem of stability analysis for a class of neutral systems with mixed time-varying neutral, discrete and distributed delays and nonlinear parameter perturbations is addressed. By introducing a novel Lyapunov-Krasovskii functional and combining the descriptor model transformation, the Leibniz-Newton formula, some free-weighting matrices, and a suitable change of variables, new sufficient conditions are established for the stability of the considered system, which are neutral-delay-dependent, discrete-delay-range dependent, and distributeddelay-dependent. The conditions are presented in terms of linear matrix inequalities (LMIs) and can be efficiently solved using convex programming techniques. Two numerical examples are given to illustrate the efficiency of the proposed method
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En aquesta tesi s'ha caracteritzat la ruta d'internalització de l'onconasa, una RNasa citotòxica. Els resultats indiquen que l'onconasa entra a les cèl·lules per la via dependent de clatrina i del complex AP-2. Seguidament es dirigeix als endosomes de reciclatge i es a través d'aquesta ruta que la proteïna exerceix la citotoxicitat. Per altra banda, els resultats d'aquest treball demostren que PE5, una variant citotòxica de la ribonucleasa pancreàtica humana (HP-RNasa), interacciona amb la importina mitjançant diferents residus que tot i que no són seqüencials, es troben propers en l'estructura tridimensional d'aquesta proteïna. PM8 és una HP-RNasa amb estructura cristal·logràfica dimèrica constituïda per intercanvi de dominis N-terminals. En aquesta tesi s'han establert les condicions per estabilitzar aquest dimer en solució i també es proposa un mecanisme per la dimerització.
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In this brief essay I shall obviously draw from my reflections which I shared over the past three decades and to which I have provided some bibliographical references. It is clear from them that I had several opportunities to share my views beyond the Anglo-Saxon world, and some of them in events organized by K. Koschorke himself in the German academic circles as Munich-Freising Conferences. It is important that we do not get misled by words. We also need clarity of the concepts involved. Koschorke’s emphasis on “ploycentric structures” requires to be discussed and analysed critically to sort out its geographic components and its political-cultural implications, in order to be clear where lie the priorities. Without such exercise we will run the risk of hiding behind the ambiguity of words and concepts. My gut feelings make me believe that “polycentric structures” is just what the West needs in the postcolonial era to replace the control it has lost with decolonization.