1,409 research outputs found

    Comparative analysis of the ΛbΛ+\Lambda_b \rightarrow \Lambda \ell^+ \ell^- decay in the SM, SUSY and RS model with custodial protection

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    We comparatively analyze the rare ΛbΛ+\Lambda _b\rightarrow \Lambda \ell^+ \ell^- channel in standard model, supersymmetry and Randall-Sundrum model with custodial protection (RSc_c). Using the parametrization of the matrix elements entering the low energy effective Hamiltonian in terms of form factors, we calculate the corresponding differential decay width and lepton forward-backward asymmetry in these models. We compare the results obtained with the most recent data from LHCb as well as lattice QCD results on the considered quantities. It is obtained that the standard model, with the form factors calculated in light-cone QCD sum rules, can not reproduce some experimental data on the physical quantities under consideration but the supersymmetry can do it. The RSc_c model predictions are roughly the same as the standard model and there are no considerable differences between the predictions of these two models. In the case of differential decay rate, the data in the range 44 GeV2/^2/c4^4\leq q26q^2 \leq 6 GeV2/^2/c4^4 can not be described by any of the considered models.Comment: 28 Pages, 12 Figures and 3 Table

    Analysis of the semileptonic ΛbΛ+\Lambda_b\rightarrow \Lambda \ell^+ \ell^- transition in topcolor-assisted technicolor (TC2) model

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    We comparatively analyze the flavor changing neutral current process of the ΛbΛ+\Lambda_b \rightarrow \Lambda \ell^+ \ell^- in the standard model as well as topcolor-assisted technicolor model using the form factors calculated via light cone QCD sum rules in full theory. In particular, we calculate the decay width, branching ratio and lepton forward-backward asymmetry related to this decay channel. We compare the results of the topcolor-assisted technicolor model with those of the standard model and debate how the results of the topcolor-assisted technicolor model depart from the standard model predictions. We also compare our results on the differential branching ratio with recent experimental data provided by CDF and LHCb Collaborations.Comment: 29 Pages, 16 Figures and 8 Table

    A sham-controlled trial of acupressure on the quality of sleep and life in haemodialysis patients

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    Background Sleep disorder in haemodialysis patients can lead to disturbance in their psychosocial function and interpersonal relations, and reduced quality of life. The aim of the present study was to investigate the effect of acupressure on the quality of sleep of haemodialysis patients. Methods In a randomised controlled trial, 108 haemodialysis patients were randomly divided into three groups: true acupressure, placebo acupressure, and no treatment. The two acupressure groups received treatment three times a week for 4 weeks during dialysis. Routine care only was provided for the no treatment group. The main study outcome was sleep quality. Results The total Pittsburgh Sleep Quality Index score decreased significantly from 11.9±3.13 to 6.2±1.93 in the true acupressure group, from 11.3±3.69 to 10.6±3.82 in the sham acupressure group, and from 10.9±4.10 to 10.7±3.94 in the no treatment group. There was a significant difference between groups (p<0.001). Conclusions Acupressure seems to have a positive effect on the sleep quality in haemodialysis patients. Clinical trial registration IRCT201106145864N2

    Environmental awareness and attitude among Iranian students in Malaysian universities

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    This study focuses on environmental awareness and attitude among Iranian students in Malaysian universities. It evaluates the awareness and attitude of a group of 541 from 14 universities. The figure to 541 is considered the representative of these students and the selection was based on Stratified Random sampling method and G-power soft ware. A set of questionnaire which comprised of 25 questions was applied as instrument for data collection. The results revealed that environmental awareness was overall moderate while environmental attitude was high. The study also found that there was no significant difference observed between sex groups while environmental awareness results indicated that there were significant difference among different levels of education. This trend was in contrast with observation for environment alattitude status. The age groups analysis results revealed significant difference in environmental awareness and attitude. It was also found that the media positively affected the level of environmental awareness and attitude among students. The study concluded that increase on age and level of education would improve the level of awareness and attitude regarding to environmental issues

    Immune and bioinformatics identification of T cell and B cell epitopes in the protein structure of SARS-CoV-2: A systematic review

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    The beginning of 2020 was marked as the emergence of a COVID-19 outbreak caused by a new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, there is no vaccine or approved treatment for this infectious virus so the invention of an efficient vaccine is certainly a high priority. Some studies have employed several techniques to facilitate the combination of the immunoinformatics approach and comparative genomic approach in order to determine the potential peptides for designing the T-cell epitope-based peptide vaccine using the 2019-nCoV envelope protein as a target. Via screening the bioimmunoinformatic SARS-CoV2 derived B-cell and T-cell epitopes within the basic immunogenic of SARS-CoV2 proteins, we presented a set of inferred B-cell and T-cell epitopes from the spike (S) and nucleocapsid (N) proteins with high antigenicity and without allergenic property or toxic effects. Our findings provide a screened set of epitopes that can be introduced as potential targets for developing peptide vaccines against the SARS-CoV-2 virus

    Phenotypic and genotypic characteristics of tetracycline resistant Acinetobacter baumannii isolates from nosocomial infections at Tehran hospitals

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    Objective(s): To date, the most important genes responsible for tetracycline resistance among Acinetobacter baumannii isolates have been identified as tet A and tet B. This study was carried out to determine the rate of resistance to tetracycline and related antibiotics, and mechanisms of resistance. Materials and Methods: During the years 2010 and 2011, a total of 100 A. baumannii isolates were recovered from patients in different hospitals of Tehran, Iran. Antimicrobial susceptibility to tetracycline, minocycline, doxicycline and tigecycline was evaluated by E-test. Polymerase chain reaction (PCR) of the tet A and tet B genes was performed using specific primers, after which the isolates were subjected to Repetitive Extragenic Palindromic-PCR (PCR) to identify the major genotypes. Results: Of all isolates, 89 were resistant to tetracycline (MIC50 = 32 mu g/ml, MIC90 = 512 mu g/ml). Minocycline with the resistant rate of 35 (MIC50 = 16 mu g/ml, MIC90 = 32 mu g/ml) and doxicycline with the resistant rate of 25 (MIC50 = 16 mu g/ml, MIC90= 32 mu g/ml) have a good activity against A. baumannii isolates. All isolates were sensitive to tigecycline. Frequencies of tet B and tet A genes and coexistence of tet A and tet B among the isolates resistant to tetracycline, were 87.6, 2.2 and 1.1, respectively. Distribution of REP-types among A. baumannii isolates was types A (40), B (30), C (10), D (5) and E (5). Conclusion: It seems that tet A and tet B genes play an important role in the induction of resistance towards tetracyclines used in this study. It is suggested that further studies focus on other antimicrobial drugs and combinations in order to achieve a successful therapy against multi drug resistance (MDR) A. baumannii strains in Iran

    Rare B Decays with a HyperCP Particle of Spin One

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    In light of recent experimental information from the CLEO, BaBar, KTeV, and Belle collaborations, we investigate some consequences of the possibility that a light spin-one particle is responsible for the three Sigma^+ -> p mu^+ mu^- events observed by the HyperCP experiment. In particular, allowing the new particle to have both vector and axial-vector couplings to ordinary fermions, we systematically study its contributions to various processes involving b-flavored mesons, including B-Bbar mixing as well as leptonic, inclusive, and exclusive B decays. Using the latest experimental data, we extract bounds on its couplings and subsequently estimate upper limits for the branching ratios of a number of B decays with the new particle. This can serve to guide experimental searches for the particle in order to help confirm or refute its existence.Comment: 17 pages, 3 figures; discussion on spin-0 case modified, few errors corrected, main conclusions unchange

    The BcB_c Decays to PP-wave Charmonium by Improved Bethe-Salpeter Approach

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    We re-calculate the exclusive semileptonic and nonleptonic decays of BcB_c meson to a PP-wave charmonium in terms of the improved Bethe-Salpeter (B-S) approach, which is developed recently. Here the widths for the exclusive semileptonic and nonleptonic decays, the form factors, and the charged lepton spectrums for the semileptonic decays are precisely calculated. To test the concerned approach by comparing with experimental measurements when the experimental data are available, and to have comparisons with the other approaches the results obtained by the approach and those by some approaches else as well as the original B-S approach, which appeared in literature, are comparatively presented and discussed.Comment: 33 pages, 5 figures, 3 table

    Gravitational form factors of Δ\Delta baryon via QCD sum rules

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    The gravitational form factors of a hadron are defined through the matrix elements of the energy-momentum tensor current, which can be decomposed into the quark and gluonic parts, between the hadronic states. These form factors provide important information for answering fundamental questions about the distribution of the energy, the spin, the pressure and the shear forces inside the hadrons. Theoretical and experimental studies of these form factors provide exciting insights on the inner structure and geometric shapes of hadrons. Inspired by this, the gravitational form factors of Δ\Delta resonance are calculated by employing the QCD sum rule approach. The acquired gravitational form factors are used to calculate the composite gravitational form factors like the energy and angular momentum multipole form factors, D-terms related to the mechanical properties like the internal pressure and shear forces as well as the mass radius of the system. The predictions are compared with the existing results in the literature.Comment: 18 Pages, 3Figures and 3 Table
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