4,662 research outputs found

    Cosmological scaling solutions of minimally coupled scalar fields in three dimensions

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    We examine Friedmann-Robertson-Walker models in three spacetime dimensions. The matter content of the models is composed of a perfect fluid, with a γ\gamma-law equation of state, and a homogeneous scalar field minimally coupled to gravity with a self-interacting potential whose energy density red-shifts as a2νa^{-2 \nu}, where a denotes the scale factor. Cosmological solutions are presented for different range of values of γ\gamma and ν\nu. The potential required to agree with the above red-shift for the scalar field energy density is also calculated.Comment: LaTeX2e, 11 pages, 4 figures. To be published in Classical and Quantum Gravit

    Fracturas patológicas en la región de la cadera

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    Entre 1973 y 1992, fueron tratados en nuestra institución 20 casos de fracturas patológicas a nivel de la cadera, secundarias a metástasis esqueléticas. Se realizó tratamiento quirúrgico mediante osteosíntesis o artroplastias según la localización y la extensión de la lesión. En 8 casos, la fractura fué subcapital, en 6 fué pertrocantérea y en otros 6 casos fué subtrocantérea. En el tratamiento quirúrgico, se recalca la importancia de la fijación interna inmediata con la adición de metilmetacrilato y el uso de la radioterapia postoperatoria. Siempre se obtuvo la mejoría del dolor y un resultado funcional bueno en el 70% de los casos. En 7 casos, aparecieron complicaciones locales. El tratamiento quirúrgico debe ser agresivo en estos pacientes, ya que la rehabilitación inmediata es primordial en su calidad de vida.From 1973 to 1992, 20 cases of pathological fractures around the hip secondary to skeletal metastases were treated in our institution. The surgical treatment was performed by internal fixation or arthroplasty according the location and extension of the lesion. In 8 cases the fracture was located in the femoral neck, 6 cases were intertrochanteric fractures and 6 cases were subtrochanteric fractures. In the surgical management the importance of inmediately internal fixation, with the use of methylnietacrilate and post surgical radiotherapy are justified. Always the pain was relieved and the functional result was good in 70%. In 7 cases were local complications. The surgical treatment should be more agresive in these special patients, because the inmediately rehabilitation is essential in your quality lifes

    Musical Heritage as a Means of Sustainable Development: Perceptions in Students Studying for a Degree in Primary Education

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    Education is an essential vehicle for valuing cultural legacy, and musical heritage is a part of that cultural legacy that we must protect as it is one of the main areas of intangible cultural heritage, a reflection of cultural diversity, and a conveyor of meaning, and social, cultural, and economic values contributing to sustainable development. The purpose of this study, therefore, is to evaluate the perception students studying for the Degree in Primary Education at the University of Zaragoza and the Autonomous University of Madrid have of the value, significance, and importance of the sustainability of musical cultural heritage. This non-experimental and descriptive research is based on the statistical descriptive method, with a sample of n = 202 preservice teachers. A questionnaire consisting of fifteen items was designed and validated as a data collection instrument. The data analysis shows differences in the analyzed categories and points to the need to take action to solve them. It also reveals the importance students attach to musical cultural heritage, to including it in the curricula of the various educational stages, and to the need to protect it as an essential requirement for sustainable development

    Integrable models and degenerate horizons in two-dimensional gravity

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    We analyse an integrable model of two-dimensional gravity which can be reduced to a pair of Liouville fields in conformal gauge. Its general solution represents a pair of ``mirror'' black holes with the same temperature. The ground state is a degenerate constant dilaton configuration similar to the Nariai solution of the Schwarzschild-de Sitter case. The existence of ϕ=const.\phi=const. solutions and their relation with the solution given by the 2D Birkhoff's theorem is then investigated in a more general context. We also point out some interesting features of the semiclassical theory of our model and the similarity with the behaviour of AdS2_2 black holes.Comment: Latex, 16 pages, 1 figur

    Testing Gaussianity on Archeops Data

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    A Gaussianity analysis using a goodness-of-fit test and the Minkowski functionals on the sphere has been performed to study the measured Archeops Cosmic Microwave Background (CMB) temperature anisotropy data for a 143 GHz Archeops bolometer. We consider large angular scales, greater than 1.8 degrees, and a large fraction of the North Galactic hemisphere, around 16%, with a galactic latitude b > 15 degrees. The considered goodness-of-fit test, first proposed by Rayner & Best (1989), has been applied to the data after a signal-to-noise decomposition. The three Minkowski functionals on the sphere have been used to construct a chi-square statistic using different thresholds. The first method has been calibrated using simulations of Archeops data containing the CMB signal and instrumental noise in order to check its asymptotic convergence. Two kind of maps produced with two different map-making techniques (coaddition and Mirage) have been analysed. Archeops maps for both Mirage and coaddition map-making, have been found to be compatible with Gaussianity. From these results we can exclude a dust and atmospheric contamination larger than 7.8% (90% CL). Also the non-linear coupling parameter f_{nl} can be constrained to be -800 < f_{nl} < 1100 at the 95% CL and on angular scales of 1.8 degrees. For comparison, the same method has been applied to data from the NASA WMAP satellite in the same region of sky. The 1-year and 3-year releases have been used. Results are compatible with those obtained with Archeops, implying in particular an upper limit for f_{nl} on degree angular scales.Comment: A&A accepted. The limits on the contamination and the fnl parameter have been improve

    Conformally dressed black hole in 2+1 dimensions

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    A three dimensional black hole solution of Einstein equations with negative cosmological constant coupled to a conformal scalar field is given. The solution is static, circularly symmetric, asymptotically anti-de Sitter and nonperturbative in the conformal field. The curvature tensor is singular at the origin while the scalar field is regular everywhere. The condition that the Euclidean geometry be regular at the horizon fixes the temperature to be T=9r+16πl2T=\frac{9\, r_+}{16\pi l^2}. Using the Hamiltonian formulation including boundary terms of the Euclidean action, the entropy is found to be 23\frac{2}{3} of the standard value (14A\frac{1}{4} A), and in agreement with the first law of thermodynamics.Comment: LaTeX ,RevTeX, 13pages, no figure

    Chromomagnetic Dipole Moment of the Top Quark Revisited

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    We study the complete one-loop contributions to the chromagnetic dipole moment Δκ\Delta\kappa of the top quark in the Standard Model, two Higgs doublet models, topcolor assited technicolor models (TC2), 331 models and extended models with a single extra dimension. We find that the SM predicts Δκ=0.056\Delta\kappa = - 0.056 and that the predictions of the other models are also consitent with the constraints imposed on Δκ\Delta\kappa by low-energy precision measurements.Comment: 20 pages, 5 figures, Updat

    Scanning Electron Microscope Study of Wohlfahrtia magnifica (Schiner, 1862) (Diptera: Sarcophagidae) I. Structures with Parasitic and Possible Taxonomic Meaning

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    The larval development of Wohlfahrtia magnifica (the most important dipteran causing sheep myiasis in the Palearctic region) has been studied by means of scanning electron microscopy. The ultrastructure of mouth-hooks, oral ridges, labial lobes, body spines and anterior and posterior peritremes is described for the first time. Their possible adaptations to a parasitic lifeway are also discussed. Thus, the use of new structures in the Sarcophagidae taxonomy is proposed from the point of view of their ultrastructure and adaptative morphology

    Resposta fotossintética de citros a isolados de Citrus tristeza virus com potencial para proteção cruzada

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    The objective of this work was to evaluate the photosynthetic response of citrus varieties to the inoculation of isolates T30 and T3 of Citrus tristeza virus (CTV) characterized as having potential to provide cross‑protection against severe CTV isolates in citrus. Citrus plants of 'Campbell' orange, 'Persian' lime, and 'Key' lime were subjected to inoculations by both isolates by patch. Noninoculated plants were used as the control. Symptom expression, photosynthetic and transpiration rates, and stomatal conductance were evaluated by IRGA. Stomatal density and size were evaluated by epidermal impressions. The CTV isolates were also evaluated and molecularly characterized by RT-PCR and Sanger sequencing. 'Campbell' orange and 'Persian' lime plants remained asymptomatic after the inoculations. The inoculation treatments with both CTV isolates did not reduce photosynthetic capacity, transpiration rate, and stomatal conductance, in comparison with the control. Stomatal density and size varied according to the citrus species. T30 and T3 do not affect the photosynthetic responses of 'Campbell' orange and 'Persian' lime; therefore, these isolates have the potential to provide cross-protection to citrus varieties against severe isolates of CTV.O objetivo deste trabalho foi avaliar a resposta fotossintética de variedades de citros submetidas à inoculação dos isolados T30 e T3 de Citrus tristeza virus (CTV) caracterizados como tendo potencial para conferir proteção cruzada a citros contra isolados severos de CTV. Plantas de citros de laranja 'Campbell', limão 'Tahiti' e limão 'Galego' foram submetidas à inoculação de ambos os isolados por “patch”. Plantas não inoculadas foram utilizadas como controle. A expressão dos sintomas,  as taxas fotossintética e de transpiração, e a condutância estomática foram avaliadas por IRGA. A densidade e o tamanho estomáticos foram avaliados por impressões epidérmicas. Os isolados de CTV também foram avaliados e caracterizados molecularmente por RT-PCR e sequenciamento de Sanger. As plantas de laranja 'Campbell' e limão 'Tahiti' permaneceram assintomáticas após as inoculações. Os tratamentos de inoculação com ambos os isolados de CTV não reduziram capacidade fotossintética, taxas de transpiração e condutância estomática, em comparação ao controle. A densidade e o tamanho estomáticos variaram de acordo com a espécie. T30 e T3 não afetam as respostas fotossintéticas de laranja 'Campbell' e limão 'Tahiti'; portanto, estes isolados têm potencial para promover proteção cruzada a variedades de citros contra isolados severos de CTV
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