162 research outputs found

    One-Electron Singular Branch Lines of the Hubbard Chain

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    The momentum and energy dependence of the weight distribution in the vicinity of the one-electron spectral-function singular branch lines of the 1D Hubbard model is studied for all values of the electronic density and on-site repulsion UU. To achieve this goal we use the recently introduced pseudofermion dynamical theory. Our predictions agree quantitatively for the whole momentum and energy bandwidth with the peak dispersions observed by angle-resolved photoelectron spectroscopy in the quasi-1D organic conductor TTF-TCNQ.Comment: Replaced with shortened version; 4 figure

    The Low-Energy Limiting Behavior of the Pseudofermion Dynamical Theory

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    In this paper we show that the general finite-energy spectral-function expressions provided by the pseudofermion dynamical theory for the one-dimensional Hubbard model lead to the expected low-energy Tomonaga-Luttinger liquid correlation function expressions. Moreover, we use the former general expressions to derive correlation-function asymptotic expansions in space and time which go beyond those obtained by conformal-field theory and bosonization: we derive explicit expressions for the pre-factors of all terms of such expansions and find that they have an universal form, as the corresponding critical exponents. Our results refer to all finite values of the on-site repulsion U and to a chain of length L very large and with periodic boundary conditions for the above model, but are of general nature for many integrable interacting models. The studies of this paper clarify the relation of the low-energy Tomonaga-Luttinger liquid behavior to the scattering mechanisms which control the spectral properties at all energy scales and provide a broader understanding of the unusual properties of quasi-one-dimensional nanostructures, organic conductors, and optical lattices of ultracold fermionic atoms. Furthermore, our results reveal the microscopic mechanisms which are behind the similarities and differences of the low-energy and finite-energy spectral properties of the model metallic phas

    Psychologist’s role in a Psychogeriatric Day Care Center

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    [Resumen] La progresiva implantación de centros asistenciales para la tercera edad, junto con la interdisciplinareidad de la actuación en valoración y posterior actuación frente a la persona mayor, hacen que el psicólogo desempeñe un papel claramente definido, y que en lo que respecta a los Centros de día psicogeriátricos, papel más importante si cabe, por las características del usuario, cada vez se beneficia más de una actuación altamente cualificada. Mediante el presente trabajo pretendemos realizar una descripción de las distintas funciones del psicólogo en un Centro de día específico para pacientes con demencia, revisando y proponiendo las diferentes actuaciones de acuerdo a sus áreas de investigación.[Abstract] The progressive establishment of assistant centers for the third age, together with the interdisciplinary of the performance in the valuation and later performance dealing with the elderly people, make psychologist plays a clearly defined part, and in what concerns to the Psychogeriatric Day Care centers, a more important role, if possible for the user’s characteristics that benefits more and more of a highly qualified performance. By means of the present work we seek to carry out a description of the psychologist’s different functions in a day care center, specific for Alzheimer’s disease patients, revising and proposing the different performances according to the intervention areas

    Helping the family carers of Alzheimer's patients: from theory... to practice: a preliminary study

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    [Abstract] Alzheimer's disease (AD) represents one of the most important health issues in the western world. The ongoing care that the AD patient requires typically causes high stress levels, fatigue, irritation and depression in the caregiver, as well as socio-economical problems. The current study aimed to introduce a support program for carers of AD patients, in order to improve their quality of life. A Questionnaire for Carers and an Anxiety State Feature Questionnaire (STAI) was used to assess the carers. Results showed an overall improvement in the carers' health. Their subjective wellbeing increased, and though their situation had not changed, they nevertheless described feeling les s trapped. It can be concluded that possibly the mere fact that the carers feel that they have help available is enough to endorse the value of the program
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