1000 resultados para Y(4260)


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Using the QCD sum rule approach we study the Y(4260) state assuming that it can be described by a mixed charmonium-tetraquark current with J(PC) = 1(--) quantum numbers. For the mixing angle around theta approximate to (53.0 +/- 0.5)degrees, we obtain a value for the mass which is in good agreement with the experimental mass of the Y(4260). For the decay width into the channel Y -> J/psi pi pi we find the value Gamma(Y -> J/psi pi pi) approximate to (4.1 +/- 0.6) MeV, which is much smaller than the total experimental width Gamma approximate to (95 +/- 14) MeV. However, considering the experimental upper limits for the decay of the Y(4260) into open charm, we conclude that we cannot rule out the possibility of describing this state as a mixed charmonium-tetraquark state. DOI: 10.1103/PhysRevD.86.116012

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We use QCD sum rules to test the nature of the recently observed mesons Y(4260), Y(4350) and Y(4660), assumed to be exotic four-quark (c (c) over barq (q) over bar) or (c (c) over bars (s) over bar) states with J(PC)= 1(--). We work at leading order in alpha(s), consider the contributions of higher dimension condensates and keep terms which are linear in the strange quark mass m(s). We find for the (c (c) over bars (s) over bar) state a mass in m(Y) = (4.65 +/- 0.10) GeV which is compatible with the experimental candidate Y (4660), while for the (c (c) over barq (q) over bar) state we find a mass in m(Y) = (4.49 +/- 0.11) GeV, which is still consistent with the mass of the experimental candidate Y(4350). With the tetraquark structure we are working we cannot explain the Y(4260) as a tetraquark state. We also consider molecular D(s0)(D) over bar (s)* and D(0)(D) over bar* states. For the D(s0)(D) over bar (s)* molecular state we get m(Ds0 (D) over bars*) = (4.42 +/- 0.10) GeV which is consistent, considering the errors, with the mass of the meson Y(4350) and for the D(0)(D) over bar* molecular state we get m(D0 (D) over bar*) = (4.27 +/- 0.10) GeV in excellent agreement with the mass of the meson Y(4260). (C) 2008 Elsevier B.V. All rights reserved.

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Tesis ( Maestría en Administración con Especialidad en Recursos Humanos) U.A.N.L.

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Resumen tomado de la publicaci??n

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Presentar un marco teórico más amplio del bilingüismo y de su importancia en la realidad española. Evaluar algunos programas internacionales en educación bilingüe y revisar las investigaciones que en materia de bilingüismo se han realizado en la red INCIE-ICEs. Revisión de la bibliografía y trabajos relacionados con el bilingüismo y análisis del caso concreto de España como país multilingüe. Estudio a nivel teórico del fenómeno del bilingüismo en sus implicaciones sociolingüísticas, psicológicas y educativas. Análisis de la situación multilingüe del Estado español y de la problemática del bilingüismo en España. Revisión de investigaciones realizadas por los ICEs. Bibliografía. Investigaciones de la red INCIE-ICEs. Revisión teórica y crítica. Se establecen diferencias entre el bilingüismo macrosocial e individual. En la realidad miltilingüe del Estado español existen claras muestras de ambos tipos de bilingüismo. Dado un programa de inversión bilingüe adecuado, con unos recursos didácticos activos, con un profesorado preparado, el bilingüismo no sólo no es un retraso sino un potenciador de un mejor dominio de las lenguas, en comprensión, vocabulario y fluidez verbal. Las investigacions realizadas por la red INCIE-ICEs sobre el bilingüismo se limitan a Santiago, Bilbao y Barcelona y representan un primer intento serio de abordar la investigación en este área. En general se evalúan positivamente. Es necesario potenciar la investigación en el área del bilingüismo como base real sobre la que tomar orientaciones educativas dentro de la realidad multilingüe del Estado español. Se proponen tres áreas de estudio: 1. Área de la Sociolingüística, 2. Área de la educación bilingüe, 3. Área de la Lingüística.

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La negociación, antes que ser una herramienta de trabajo dirigida a la resolución de conflictos y a la consecución de acuerdos, se caracteriza por una componente fundamental, a veces desestimada o del todo ignorada: el hecho que obliga a un previo proceso de introspección y de autoanálisis, lo que finalmente facilita el proceso de comunicación con nuestro entorno.

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Antecedentes El manejo de este tema es parte integral del trabajo del IICA (Instituto Interamericano de Cooperacion para la Agricultura) realiza por medio de la Secretaria Técnica del Comité de Desarrollo Sostenible (CODES). En la actualidad, el desarrollo sostenible del medio rural ha pasado a ocupar un primer plano en la agenda política mundial. Esta situación no es obra de la casualidad: es el resultado de un claro entendimiento de la vinculación existente entre el potenciamiento de ese sector y el proceso de desarrollo nacional; es producto, también, de la comprensión del impacto que las actividades económicas gestadas en ese medio tiene sobre la base de los recursos naturales…

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The aim of this cephalometric study was to evaluate the influence of the sagittal skeletal pattern on the 'Y-axis of growth' measurement in patients with different malocclusions. Lateral head films from 59 patients (mean age 16y 7m, ranging from 11 to 25 years) were selected after a subjective analysis of 1630 cases. Sample was grouped as follows: Group 1 - class I facial pattern; group 2 - class II facial pattern; and Group 3 - class III facial pattern. Two angular measurements, SNGoGn and SNGn, were taken in order to determine skeletal vertical facial pattern. A logistic regression with errors distributed according to a binomial distribution was used to test the influence of the sagittal relationship (Class I, II, III facial patterns) on vertical diagnostic measurement congruence (SNGoGn and SNGn). RESULTS show that the probability of congruence between the patterns SNGn and SNGoGn was relatively high (70%) for group 1, but for groups II (46%) and III (37%) this congruence was relatively low. The use of SNGn appears to be inappropriate to determine the vertical facial skeletal pattern of patients, due to Gn point shifting throughout sagittal discrepancies. Clinical Significance: Facial pattern determined by SNGn must be considered carefully, especially when severe sagittal discrepancies are present.

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Nonalcoholic fatty liver disease (NAFLD) is common among subjects who undergo bariatric surgery and its postsurgical improvement has been reported. This study aimed to determine the evolution of liver disease evaluated through NAFLD fibrosis score 12 months after surgery. It is a prospective cohort study which evaluated patients immediately before and 12 months following Roux-en-Y gastric bypass (RYGB). Mean score decreased from 1.142 to 0.066; surgery led to a resolution rate of advanced fibrosis of 55 %. Resolution was statistically associated with female gender, percentage of excess weight loss, postsurgical body mass index, postsurgical platelet count, and diabetes resolution. As previously reported by studies in which postsurgical biopsies were performed, RYGB leads to a great resolution rate of liver fibrosis. Since postsurgical biopsy is not widely available and has a significant risk, calculation of NAFLD fibrosis score is a simple tool to evaluate this evolution through a noninvasive approach.

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Weight loss failure is a widely recognized occurrence following Roux-en-Y gastric bypass. This study aims to identify predictors associated with weight loss failure. It is a retrospective cohort which enrolled 187 subjects who underwent RYGB. Comparisons were made between patients' features at baseline and 24 months after surgery. A weight loss failure rate of 11.2% was found. Advanced age and diabetes were statistically associated with failure. The results found were close to previous reports. As weight loss failure represents an important concern, there is the possibility to perform revisional surgeries, which may emphasize the restrictive or malabsorptive characteristics of RYGB, leading to varied results. It is reinforced that weight loss cannot be used as the unique outcome to evaluate the success of surgery.