13,773 research outputs found

    Combining exclusive semi-leptonic and hadronic B decays to measure |V_ub|

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    The Cabibbo-Kobayashi-Maskawa matrix element |V_ub| can be extracted from the rate for the semi-leptonic decay B -> pi + l + antineutrino_l, with little theoretical uncertainty, provided the hadronic form factor for the B -> pi transition can be measured from some other B decay. In here, we suggest using the decay B -> pi J\psi. This is a color suppressed decay, and it cannot be properly described within the usual factorization approximation; we use instead a simple and very general phenomenological model for the b d J\psi vertex. In order to relate the hadronic form factors in the B -> pi J\psi and B -> pi + l + antineutrino_l decays, we use form factor relations that hold for heavy-to-light transitions at large recoil.Comment: Latex, 7 pages, no figure

    Rearranjos Subteloméricos: Apresentação de 21 Probandos, com Ênfase nos Casos Familiares

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    Intellectual disability affects 2% - 3% of the general population, with a chromosomal abnormality being found in 4% - 28% of these patients and a cryptic subtelomeric abnormality in 3% - 16%. In most cases, these subtelomeric rearrangements are submicroscopic, requiring techniques other than conventional karyotype for detection. They may be de novo or inherited from an affected parent or from a healthy carrier of a balanced chromosomal abnormality. The aim of this study was to characterize patients from our medical genetics center, in whom both a deletion and duplication in subtelomeric regions were found.Introdução:O défice intelectual afeta 2% – 3% da população geral, sendo encontrada uma alteração cromossómica em 4% – 28% dos casos e uma alteração subtelomérica em 3% – 16%. Estas alterações subteloméricas são, na maioria dos casos, submicroscópicas, não sendo detetadas no cariótipo convencional. Podem ser de novoou herdadas de um progenitor afetado ou de um progenitor saudável portador de um rearranjo equilibrado. O objetivo deste estudo foi caracterizar os doentes seguidos no nosso centro de genética médica com uma deleção e uma duplicação nas regiões subteloméricas. Material e Métodos:Caracterização clínica e citogenética de 21 probandos com alterações subteloméricas seguidos no nosso centro entre 1998 e 2017. Resultados:Foram caracterizados 21 probandos que apresentavam défice intelectual e dismorfia facial, pertencentes a 19 famílias. Sete tinham alterações do comportamento, cinco epilepsia e 14 outro sinal ou sintoma. Quatro tinham alterações no cariótipo e quatro foram diagnosticados por array-comparative genomic hybridization. Em quatro famílias não foi possível o estudo dos progenitores. Quando um dos fenótipos era dominante (síndrome de deleção ou duplicação), foi atribuída a classificação online mendelian inheritance in man. Discussão:Foi realizada classificação dos doentes e das famílias. As alterações nas regiões subteloméricas são, apesar de raras, uma causa substancial para défice intelectual sindrómico com repercussões familiares importantes. É essencial lembrar que um arraycomparative genomic hybridizationnormal não exclui um rearranjo equilibrado familiar. Conclusão:O estudo dos progenitores é essencial não só para caracterização completa do rearranjo mas também para um aconselhamento genético preciso e identificação de familiares em risco de recorrência. Palavras-chave:Deficiência Intelectual/genética; Rearranjo Génico/genética; Telómero/genéticainfo:eu-repo/semantics/publishedVersio

    Nonfactorization in Hadronic Two-body Cabibbo-favored decays of D^0 and D^+

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    With the inclusion of nonfactorized amplitudes in a scheme with Nc=3N_c=3, we have studied Cabibbo-favored decays of D0D^0 and D+D^+ into two-body hadronic states involving two isospins in the final state. We have shown that it is possible to understand the measured branching ratios and determined the sizes and signs of nonfactorized amplitudes required.Comment: 15 pages, Late

    Exact Nonequilibrium Work Generating Function for a Small Classical System

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    We obtain the exact nonequilibrium work generating function (NEWGF), for a small system consisting of a massive Brownian particle connected to internal and external springs. The external work is provided to the system for a finite time interval. The Jarzynski equality (JE), obtained in this case directly from the NEWGF, is shown to be valid for the present model, in an exact way regardless of the rate of external work

    Nonfactorization and Color-Suppressed Bψ(ψ(2S))+K(K)B \to \psi (\psi(2S))+K(K^*) Decays

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    Using Nc=3N_c=3 value of the parameter a2=0.09a_2=0.09 but including a modest nonfactorized amplitude, we show that it is possible to understand all data, including polarization, for color-suppressed Bψ(ψ(2S))+K(K)B\to\psi(\psi(2S))+K(K^*) decays in all commonly used models of form factors. We show that for Bψ+KB\to\psi +K decay one can define an effective a2 a_2, which is process-dependent and, in general, complex; but it is not possible to define an effective a2a_2 for Bψ+KB\to\psi +K^* decay. We also explain why nonfactorized amplitudes do not play a significant role in color-favored B decays.Comment: 13 pages, Latex, one figure (not included

    Avaliação, seleção e recomendação de cutlivares de arroz de várzeas em Minas Gerais de 1997 a 2002.

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    A fim de tornar a orizicultura irrigada uma atividade mais atrativa, a EPAMIG desenvolve, em parceria com a EMBRAPA Arroz e Feijão, pesquisas de melhoramento genético de arroz de várzeas com o objetivo de obter cultivares superiores às já recomendadas, tanto em produtividade como em aceitação comercial

    Comment on ``BCS to Bose-Einstein crossover phase diagram at zero temperature for a d_{x^2-y^2} order parameter superconductor: Dependence on the tight-binding structure''

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    The work by Soares et al. [Phys. Rev. B 65, 174506 (2002)] investigates the BCS-BE crossover for d-wave pairing in the 2-dimensional attractive Hubbard model. Contrary to their claims, we found that a non-pairing region does not exist in the density vs coupling phase diagram. The gap parameter at T=0, as obtained by solving analytically as well as numerically the BCS equations, is in fact finite for any non-zero density and coupling, even in the weak-coupling regime.Comment: 7 pages, 1 figur

    Groove Pancreatitis with Biliary and Duodenal Stricture: An Unusual Cause of Obstructive Jaundice

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    INTRODUCTION: Groove pancreatitis is an uncommon cause of chronic pancreatitis that affects the groove anatomical area between the head of the pancreas, duodenum, and common bile duct. CLINICAL CASE: A 67-year-old man with frequent biliary colic and an alcohol consumption of 30-40 g/day was admitted to the hospital complaining of jaundice and pruritus. Laboratory analysis revealed cholestasis and the ultrasound scan showed intra-hepatic biliary ducts dilatation, middle third cystic dilatation of common bile duct, enlarged Wirsung and pancreatic atrophy. The magnetic resonance cholangiopancreatography showed imaging findings compatible with groove pancreatitis. An esophagogastroduodenoscopy later excluded duodenal neoplasia. He was submitted to a Roux-en-Y cholangiojejunostomy because of common bile duct stricture. Five months later a gastrojejunostomy was performed due to a duodenal stricture. The patient remains asymptomatic during follow-up. DISCUSSION: Groove pancreatitis is a benign cause of obstructive jaundice, whose main differential diagnosis is duodenal or pancreatic neoplasia. When this condition causes duodenal or biliary stricture, surgical treatment can be necessary.info:eu-repo/semantics/publishedVersio
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