789 research outputs found

    Quasi-two-body decays Bηc(1S,2S)  [ρ(770),ρ(1450),ρ(1700)]  ππB \to \eta_c {(1S ,2S)}\;[\rho(770),\rho(1450),\rho(1700) \to ]\; \pi\pi in the perturbative QCD approach

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    In this paper, we calculated the branching ratios of the quasi-two-body decays Bηc(1S,2S)B \to \eta_c (1S ,2S) [ρ(770),ρ(1450),ρ(1700)]ππ[\rho(770), \rho(1450),\rho(1700)\to ] \pi\pi by employing the perturbative QCD (PQCD) approach. The contributions from the PP-wave resonances ρ(770)\rho(770), ρ(1450)\rho(1450) and ρ(1700)\rho(1700) were taken into account. The two-pion distribution amplitude ΦππP\Phi_{\pi\pi}^{\rm P} is parameterized by the vector current time-like form factor FπF_{\pi} to study the considered decay modes. We found that (a) the PQCD predictions for the branching ratios of the considered quasi-two-body decays are in the order of 10710610^{-7} \sim 10^{-6}, while the two-body decay rates B(Bηc(1S,2S)(ρ(1450),ρ(1700))){\cal B}(B \to \eta_c{(1S,2S)} (\rho(1450),\rho(1700))) are extracted from those for the corresponding quasi-two-body decays; (b) the whole pattern of the pion form factor-squared Fπ2|F_\pi|^2 measured by the BABAR Collaboration could be understood based on our theoretical results; (c) the general expectation based on the similarity between BηcππB \to \eta_c \pi\pi and BJ/ψππB \to J/\psi \pi\pi decays are confirmed: R2(ηc)0.45R_2(\eta_c)\approx 0.45 is consistent with the measured R2(J/ψ)0.56±0.09R_2(J/\psi)\approx 0.56\pm 0.09 within errors; and (d) new ratios R3(ηc(1S))R_3(\eta_c(1S)) and R4(ηc(2S))R_4(\eta_c(2S)) among the branching ratios of the considered decay modes are defined and could be tested by future experiments.Comment: 10 pages, 3 figure

    Quasi-two-body decays BDK(892)DKπB \to D K^*(892) \to D K \pi in the perturbative QCD approach

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    We study the quasi-two-body decays BDK(892)DKπB\to D K^*(892) \to D K\pi by employing the perturbative QCD approach. The two-meson distribution amplitudes \Phi_{K\pi}^{\text{P-wave}} are adopted to describe the final state interactions of the kaon-pion pair in the resonance region. The resonance line shape for the PP-wave KπK\pi component K(892)K^*(892) in the time-like form factor FKπ(s)F_{K\pi}(s) is parameterized by the relativistic Breit-Wigner function. For most considered decay modes, the theoretical predictions for their branching ratios are consistent with currently available experimental measurements within errors. We also disscuss some ratios of the branching fractions of the concerned decay processes. More precise data from LHCb and Belle-II are expected to test our predictions.Comment: 10 pages, 3 figures and 2 tables.To be published in EPJ

    Fasciolopsis buski (Digenea: Fasciolidae) from China and India may represent distinct taxa based on mitochondrial and nuclear ribosomal DNA sequences

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    Sequences of primers used to amplify fragments of Fasciolopsis buski mitochondrial genome. (DOCX 17 kb

    Blood Pressure Reduction Combining Baroreflex Restoration for Stroke Prevention in Hypertension in Rats

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    Blood pressure reduction is an important and effective strategy in stroke prevention in hypertensives. Recently, we found that baroreflex restoration was also crucial in stroke prevention. The present work was designed to test the hypothesis that a combination of blood pressure reduction and baroreflex restoration may be a new strategy for stroke prevention. In Experiment 1, the effects of ketanserin (0.3, 1, 3, 10 mg/kg), amlodipine (0.3, 1, 2, 3 mg/kg) and their combination (1 + 0.3, 1 + 1, 1 + 2, 1 + 3 mg/kg) on blood pressure and baroreflex sensitivity (BRS) of stroke-prone spontaneously hypertensive rats (SHR-SP) were determined under conscious state. It was found that both amlodipine and ketanserin decreased blood pressure dose-dependently. Ketanserin enfanced BRS from a very small dose but amlodipine enfanced BRS only at largest dose used. At the dose of 1 + 2 mg/kg (ketanserin + amlodipine), the combination possessed the largest synergism on blood pressure reduction. In Experiments 2 and 3, SHR-SP and two-kidney, two-clip (2K2C) renovascular hypertensive rats received life-long treatments with ketanserin (1 mg/kg) and amlodipine (2 mg/kg) or their combination (0.5 + 1, 1 + 2, 2 + 4 mg/kg). The survival time was recorded and the brain lesion was examined. It was found that all kinds of treatments prolonged the survival time of SHR-SP and 2K2C rats. The combination possessed a significantly better effect on stroke prevention than mono-therapies. In conclusion, combination of blood pressure reduction and baroreflex restoration may be a new strategy for the prevention of stroke in hypertension

    Genetic variations of the porcine PRKAG3 gene in Chinese indigenous pig breeds

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    Four missense substitutions (T30N, G52S, V199I and R200Q) in the porcine PRKAG3 gene were considered as the likely candidate loci affecting meat quality. In this study, the R200Q substitution was investigated in a sample of 62 individuals from Hampshire, Chinese Min and Erhualian pigs, and the genetic variations of T30N, G52S and V199I substitutions were detected in 1505 individuals from 21 Chinese indigenous breeds, 5 Western commercial pig breeds, and the wild pig. Allele 200R was fixed in Chinese Min and Erhualian pigs. Haplotypes II-QQ and IV-QQ were not observed in the Hampshire population, supporting the hypothesis that allele 200Q is tightly linked with allele 199V. Significant differences in allele frequencies of the three substitutions (T30N, G52S and V199I) between Chinese indigenous pigs and Western commercial pigs were observed. Obvious high frequencies of the "favorable" alleles 30T and 52G in terms of meat quality were detected in Chinese indigenous pigs, which are well known for high meat quality. However, the frequency of the "favorable" allele 199I, which was reported to have a greater effect on meat quality in comparison with 30T and 52G, was very low in all of the Chinese indigenous pigs except for the Min pig. The reasons accounting for this discrepancy remain to be addressed. The presence of the three substitutions in purebred Chinese Tibetan pigs indicates that the three substitutions were ancestral mutations. A novel A/G substitution at position 51 in exon 1 was identified. The results suggest that further studies are required to investigate the associations of these substitutions in the PRKAG3 gene with meat quality of Chinese indigenous pigs, and to uncover other polymorphisms in the PRKAG3 gene with potential effects on meat quality in Chinese indigenous pigs
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