2,594 research outputs found

    Solutions of Several Coupled Discrete Models in terms of Lame Polynomials of Order One and Two

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    Coupled discrete models abound in several areas of physics. Here we provide an extensive set of exact quasiperiodic solutions of a number of coupled discrete models in terms of Lame polynomials of order one and two. Some of the models discussed are (i) coupled Salerno model, (ii) coupled Ablowitz-Ladik model, (iii) coupled saturated discrete nonlinear Schrodinger equation, (iv) coupled phi4 model, and (v) coupled phi6 model. Furthermore, we show that most of these coupled models in fact also possess an even broader class of exact solutions.Comment: 31 pages, to appear in Pramana (Journal of Physics) 201

    Isotopic variation of parity violation in atomic ytterbium

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    We report on measurements of atomic parity violation, made on a chain of ytterbium isotopes with mass numbers A=170, 172, 174, and 176. In the experiment, we optically excite the 6s2 1S0 -> 5d6s 3D1 transition in a region of crossed electric and magnetic fields, and observe the interference between the Stark- and weak-interaction-induced transition amplitudes, by making field reversals that change the handedness of the coordinate system. This allows us to determine the ratio of the weak-interaction-induced electric-dipole (E1) transition moment and the Stark-induced E1 moment. Our measurements, which are at the 0.5% level of accuracy for three of the four isotopes measured, allow a definitive observation of the isotopic variation of the weak-interaction effects in an atom, which is found to be consistent with the prediction of the Standard Model. In addition, our measurements provide information about an additional Z' boson.Comment: 19 pages, 4 figures, 2 table

    Two loop electroweak corrections to BˉXsγ\bar B\rightarrow X_s\gamma and Bs0μ+μB_s^0\rightarrow \mu^+\mu^- in the B-LSSM

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    The rare decays BˉXsγ\bar B\rightarrow X_s\gamma and Bs0μ+μB_s^0\rightarrow \mu^+\mu^- are important to research new physics beyond standard model. In this work, we investigate two loop electroweak corrections to BˉXsγ\bar B\rightarrow X_s\gamma and Bs0μ+μB_s^0\rightarrow \mu^+\mu^- in the minimal supersymmetric extension of the SM with local BLB-L gauge symmetry (B-LSSM), under a minimal flavor violating assumption for the soft breaking terms. In this framework, new particles and new definition of squarks can affect the theoretical predictions of these two processes, with respect to the MSSM. Considering the constraints from updated experimental data, the numerical results show that the B-LSSM can fit the experimental data for the branching ratios of BˉXsγ\bar B\rightarrow X_s\gamma and Bs0μ+μB_s^0\rightarrow \mu^+\mu^-. The results of the rare decays also further constrain the parameter space of the B-LSSM.Comment: 33 pages, 9 figures, Published in EPJ

    Schoolgirls’ experience and appraisal of menstrual absorbents in rural Uganda: a cross-sectional evaluation of reusable sanitary pads

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    BACKGROUND: Governments, multinational organisations, and charities have commenced the distribution of sanitary products to address current deficits in girls’ menstrual management. The few effectiveness studies conducted have focused on health and education outcomes but have failed to provide quantitative assessment of girls’ preferences, experiences of absorbents, and comfort. Objectives of the study were, first, to quantitatively describe girls’ experiences with, and ratings of reliability and acceptability of different menstrual absorbents. Second, to compare ratings of freely-provided reusable pads (AFRIpads) to other existing methods of menstrual management. Finally, to assess differences in self-reported freedom of activity during menses according to menstrual absorbent. // METHODS: Cross-sectional, secondary analysis of data from the final survey of a controlled trial of reusable sanitary padand puberty education provision was undertaken. Participants were 205 menstruating schoolgirls from eight schools in rural Uganda. 72 girls who reported using the intervention-provided reusable pads were compared to those using existing improvised methods (predominately new or old cloth). // RESULTS: Schoolgirls using reusable pads provided significantly higher ratings of perceived absorbent reliability across activities, less difficulties changing absorbents, and less disgust with cleaning absorbents. There were no significant differences in reports of outside garment soiling (OR 1.00 95%CI 0.51–1.99), or odour (0.84 95%CI 0.40–1.74) during the last menstrual period. When girls were asked if menstruation caused them to miss daily activities there were no differences between those using reusable pads and those using other existing methods. However, when asked about activities avoided during menstruation, those using reusable pads participated less in physical sports, working in the field, fetching water, and cooking. // CONCLUSIONS: Reusable pads were rated favourably. This translated into some benefits for self-reported involvement in daily activities, although reports of actual soiling and missing activities due to menstruation did not differ. More research is needed comparing the impact of menstrual absorbents on girls’ daily activities, and validating outcome measures for menstrual management research

    Dopamine Induced Neurodegeneration in a PINK1 Model of Parkinson's Disease

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    Parkinson's disease is a common neurodegenerative disease characterised by progressive loss of dopaminergic neurons, leading to dopamine depletion in the striatum. Mutations in the PINK1 gene cause an autosomal recessive form of Parkinson's disease. Loss of PINK1 function causes mitochondrial dysfunction, increased reactive oxygen species production and calcium dysregulation, which increases susceptibility to neuronal death in Parkinson's disease. The basis of neuronal vulnerability to dopamine in Parkinson's disease is not well understood

    Successful bone marrow transplantation in a patient with Diamond-Blackfan anemia with co-existing Duchenne muscular dystrophy: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Diamond-Blackfan anemia and Duchenne muscular dystrophy are two rare congenital anomalies. Both anomalies occurring in the same child is extremely rare. Allogeneic hematopoietic stem cell transplantation is a well-established therapy for Diamond-Blackfan anemia. However, in patients with Duchenne muscular dystrophy, stem cell therapy still remains experimental.</p> <p>Case presentation</p> <p>We report the case of a nine-year-old boy of north Indian descent with Diamond-Blackfan anemia and Duchenne muscular dystrophy who underwent successful allogeneic hematopoietic stem cell transplantation. He is transfusion-independent, and his Duchenne muscular dystrophy has shown no clinical deterioration over the past 45 months. His creatine phosphokinase levels have significantly decreased to 300 U/L from 14,000 U/L pre-transplant. The patient is 100% donor chimera in the hematopoietic system, and his muscle tissue has shown 8% to 10.4% cells of donor origin.</p> <p>Conclusion</p> <p>Our patient's Diamond-Blackfan anemia was cured by allogeneic hematopoietic stem cell transplantation. The interesting clinical observation of a possible benefit in Duchenne muscular dystrophy cannot be ruled out. However, further clinical follow-up with serial muscle biopsies and molecular studies are needed to establish this finding.</p

    Insecticide Susceptibility of Phlebotomus argentipes in Visceral Leishmaniasis Endemic Districts in India and Nepal

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    Visceral leishmaniasis (VL), also know as kala azar, is one of the major public health concerns India, Nepal and Bangladesh. In the Indian subcontinent, VL is caused by Leishmania donovani which is transmitted by Phlebotomus argentipes. To date, Indoor Residual Spraying (IRS) campaigns have been unable to control the disease. Vector resistance to the insecticides used has been postulated as one of the possible reasons explaining this failure. A number of studies in the region have shown a variable degree of resistance to DDT in areas where this insecticide has been widely used for IRS (mainly India). However there is no coordinated and standardized program to monitor resistance to insecticides in the region. In this study we tested P. argentipes susceptibility to DDT and deltamethrin in VL endemic villages in India and Nepal. The results confirmed the DDT resistance in India and in a border village of Nepal. P. argentipes from both countries were in general susceptible to deltamethrin, an insecticide used in some long lasting insecticidal nets

    A Primer on Regression Methods for Decoding cis-Regulatory Logic

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    The rapidly emerging field of systems biology is helping us to understand the molecular determinants of phenotype on a genomic scale [1]. Cis-regulatory elements are major sequence-based determinants of biological processes in cells and tissues [2]. For instance, during transcriptional regulation, transcription factors (TFs) bind to very specific regions on the promoter DNA [2,3] and recruit the basal transcriptional machinery, which ultimately initiates mRNA transcription (Figure 1A). Learning cis-Regulatory Elements from Omics Data A vast amount of work over the past decade has shown that omics data can be used to learn cis-regulatory logic on a genome-wide scale [4-6]--in particular, by integrating sequence data with mRNA expression profiles. The most popular approach has been to identify over-represented motifs in promoters of genes that are coexpressed [4,7,8]. Though widely used, such an approach can be limiting for a variety of reasons. First, the combinatorial nature of gene regulation is difficult to explicitly model in this framework. Moreover, in many applications of this approach, expression data from multiple conditions are necessary to obtain reliable predictions. This can potentially limit the use of this method to only large data sets [9]. Although these methods can be adapted to analyze mRNA expression data from a pair of biological conditions, such comparisons are often confounded by the fact that primary and secondary response genes are clustered together--whereas only the primary response genes are expected to contain the functional motifs [10]. A set of approaches based on regression has been developed to overcome the above limitations [11-32]. These approaches have their foundations in certain biophysical aspects of gene regulation [26,33-35]. That is, the models are motivated by the expected transcriptional response of genes due to the binding of TFs to their promoters. While such methods have gathered popularity in the computational domain, they remain largely obscure to the broader biology community. The purpose of this tutorial is to bridge this gap. We will focus on transcriptional regulation to introduce the concepts. However, these techniques may be applied to other regulatory processes. We will consider only eukaryotes in this tutorial
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