965 resultados para Gelfand-Dickey formalism
Resumo:
Este estudio analiza la existencia de conceptos y estrategias comunitarias en relación de cómo una empresa en el sector de servicios sociales y salud entienden las estrategias de mercadeo y la influencia en el desempeño que pueden tener en su relación con el entorno. Para esto, se utilizo un enfoque de estudio de caso seleccionando un caso representativo con una empresa dentro del sector. Se definieron proposiciones y protocolos. Varias fuentes de evidencia fueron utilizadas como documentos, reportes de desempeño financiero y otra información de diferentes sectores relacionados; los mismos fueron analizados en el marco de la evidencia lógica. Se concluye que la empresa en el sector de servicios sociales y salud no utilizan conceptos ni estrategias comunitarias y que se podrían beneficiar del uso apropiado de estrategias comunitarias en su relación con la comunidad.
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Revisión crítica de la ‘versión heredada’ sobre el resurgir del pragmatismo norteamericano. Aquí sostengo que ésta es una narrativa sobre la historia de la filosofía que puede ser usada para “reivindicar” la continuidad o para “añorar” la pérdida de esa tradición. Presento tres argumentos a favor de mi tesis sobre la versión heredada: i) es insuficiente para explicar el surgimiento del pragmatismo; ii) es un tipo de narrativa que hace plausible una imagen de la filosofía; iii) impide apreciar que la formación del canon obedece a los propósitos de los seguidores del movimiento.
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El documento examina el efecto de filtros de ajuste en el tamaño y poder de prueba de cointegración que usan los residuales como pruebas ADF y PP, mediante procedimientos MonteCarlo y una aplicación empírica. Nuestros resultados indican que el uso de filtros distorsiona el tamaño y reduce el poder de estas pruebas.
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Two common methods of accounting for electric-field-induced perturbations to molecular vibration are analyzed and compared. The first method is based on a perturbation-theoretic treatment and the second on a finite-field treatment. The relationship between the two, which is not immediately apparent, is made by developing an algebraic formalism for the latter. Some of the higher-order terms in this development are documented here for the first time. As well as considering vibrational dipole polarizabilities and hyperpolarizabilities, we also make mention of the vibrational Stark effec
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Les restriccions reals quantificades (QRC) formen un formalisme matemàtic utilitzat per modelar un gran nombre de problemes físics dins els quals intervenen sistemes d'equacions no-lineals sobre variables reals, algunes de les quals podent ésser quantificades. Els QRCs apareixen en nombrosos contextos, com l'Enginyeria de Control o la Biologia. La resolució de QRCs és un domini de recerca molt actiu dins el qual es proposen dos enfocaments diferents: l'eliminació simbòlica de quantificadors i els mètodes aproximatius. Tot i això, la resolució de problemes de grans dimensions i del cas general, resten encara problemes oberts. Aquesta tesi proposa una nova metodologia aproximativa basada en l'Anàlisi Intervalar Modal, una teoria matemàtica que permet resoldre problemes en els quals intervenen quantificadors lògics sobre variables reals. Finalment, dues aplicacions a l'Enginyeria de Control són presentades. La primera fa referència al problema de detecció de fallades i la segona consisteix en un controlador per a un vaixell a vela.
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We consider boundary value problems for the N-wave interaction equations in one and two space dimensions, posed for x [greater-or-equal, slanted] 0 and x,y [greater-or-equal, slanted] 0, respectively. Following the recent work of Fokas, we develop an inverse scattering formalism to solve these problems by considering the simultaneous spectral analysis of the two ordinary differential equations in the associated Lax pair. The solution of the boundary value problems is obtained through the solution of a local Riemann–Hilbert problem in the one-dimensional case, and a nonlocal Riemann–Hilbert problem in the two-dimensional case.
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The brace notation, introduced by Allen and Csaszar (1993, J. chem. Phys., 98, 2983), provides a simple and compact way to deal with derivatives of arbitrary non-tensorial quantities. One of its main advantages is that it builds the permutational symmetry of the derivatives directly into the formalism. The brace notation is applied to formulate the general nth-order Cartesian derivatives of internal coordinates, and to provide closed forms for general, nth-order transformation equations of anharmonic force fields, expressed as Taylor series, from internal to Cartesian or normal coordinate spaces.
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Formulas are derived for the quartic anharmonic resonance coefficients observed to be important between C–H stretching and the combination of one quantum of C≡C stretching and two quanta of H–C≡C bending in a number of acetylene molecules. Examples of this resonance are ν3 with ν2+ν4+ν5 in 12C2H2, ν1 with ν2+2ν5 in 13C2H2, and ν1 with ν2+2ν4 in monofluoroacetylene and monochloroacetylene. The coefficients characterizing the resonances in these examples, which we denote K3,245, K1,255, and K1,244, arise from cubic and quartic terms in the anharmonic force field, in the normal coordinate representation, through second order and first order perturbation treatments respectively, where the second order resonances are calculated by a Van Vleck resonance formalism. The experimentally determined values of these coefficients are compared with values calculated from model anharmonic force fields.
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A comparison of the models of Vitti et al. (2000, J. Anim. Sci. 78, 2706-2712) and Fernandez (1995c, Livest. Prod. Sci. 41, 255-261) was carried out using two data sets on growing pigs as input. The two models compared were based on similar basic principles, although their aims and calculations differed. The Vitti model employs the rate:state formalism and describes phosphorus (P) flow between four pools representing P content in gut, blood, bone and soft tissue in growing goats. The Fernandez model describes flow and fractional recirculation between P pools in gut, blood and bone in growing pigs. The results from both models showed similar trends for P absorption from gut to blood and net retention in bone with increasing P intake, with the exception of the 65 kg results from Date Set 2 calculated using the FernAndez model. Endogenous loss from blood back to gut increased faster with increasing P intake in the FernAndez than in the Vitti model for Data Set 1. However, for Data Set 2, endogenous loss increased with increasing P intake using the Vitti model, but decreased when calculated using the FernAndez model. Incorporation of P into bone was not influenced by intake in the FernAndez model, while in the Vitti model there was an increasing trend. The FernAndez model produced a pattern of decreasing resorption in bone with increasing P intake, with one of the data sets, which was not observed when using the Vitti model. The pigs maintained their P homeostasis in blood by regulation of P excretion in urine. (c) 2005 Elsevier Ltd. All rights reserved.
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Multiscale modeling is emerging as one of the key challenges in mathematical biology. However, the recent rapid increase in the number of modeling methodologies being used to describe cell populations has raised a number of interesting questions. For example, at the cellular scale, how can the appropriate discrete cell-level model be identified in a given context? Additionally, how can the many phenomenological assumptions used in the derivation of models at the continuum scale be related to individual cell behavior? In order to begin to address such questions, we consider a discrete one-dimensional cell-based model in which cells are assumed to interact via linear springs. From the discrete equations of motion, the continuous Rouse [P. E. Rouse, J. Chem. Phys. 21, 1272 (1953)] model is obtained. This formalism readily allows the definition of a cell number density for which a nonlinear "fast" diffusion equation is derived. Excellent agreement is demonstrated between the continuum and discrete models. Subsequently, via the incorporation of cell division, we demonstrate that the derived nonlinear diffusion model is robust to the inclusion of more realistic biological detail. In the limit of stiff springs, where cells can be considered to be incompressible, we show that cell velocity can be directly related to cell production. This assumption is frequently made in the literature but our derivation places limits on its validity. Finally, the model is compared with a model of a similar form recently derived for a different discrete cell-based model and it is shown how the different diffusion coefficients can be understood in terms of the underlying assumptions about cell behavior in the respective discrete models.
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G3B3 and G2MP2 calculations using Gaussian 03 have been carried out to investigate the protonation preferences for phenylboronic acid. All nine heavy atoms have been protonated in turn. With both methodologies, the two lowest protonation energies are obtained with the proton located either at the ipso carbon atom or at a hydroxyl oxygen atom. Within the G3B3 formalism, the lowest-energy configuration by 4.3 kcal . mol(-1) is found when the proton is located at the ipso carbon, rather than at the electronegative oxygen atom. In the resulting structure, the phenyl ring has lost a significant amount of aromaticity. By contrast, calculations with G2MP2 show that protonation at the hydroxyl oxygen atom is favored by 7.7 kcal . mol(-1). Calculations using the polarizable continuum model (PCM) solvent method also give preference to protonation at the oxygen atom when water is used as the solvent. The preference for protonation at the ipso carbon found by the more accurate G3B3 method is unexpected and its implications in Suzuki coupling are discussed. (C) 2006 Wiley Periodicals, Inc.
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This paper tackles the problem of computing smooth, optimal trajectories on the Euclidean group of motions SE(3). The problem is formulated as an optimal control problem where the cost function to be minimized is equal to the integral of the classical curvature squared. This problem is analogous to the elastic problem from differential geometry and thus the resulting rigid body motions will trace elastic curves. An application of the Maximum Principle to this optimal control problem shifts the emphasis to the language of symplectic geometry and to the associated Hamiltonian formalism. This results in a system of first order differential equations that yield coordinate free necessary conditions for optimality for these curves. From these necessary conditions we identify an integrable case and these particular set of curves are solved analytically. These analytic solutions provide interpolating curves between an initial given position and orientation and a desired position and orientation that would be useful in motion planning for systems such as robotic manipulators and autonomous-oriented vehicles.