359 research outputs found

    Zero modes and charged Skyrmions in graphene bilayer

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    We show that the electric charge of the Skyrmion in the vector order parameters that characterize the quantum anomalous spin Hall state and the layer-antiferromagnet in a graphene bilayer is four and zero, respectively. The result is based on the demonstration that a vortex configuration in two broken symmetry states in bilayer graphene with the quadratic band crossing has the number of zero modes doubled relative to the single layer. The doubling can be understood as a result of Kramers' theorem implied by the "pseudo time reversal" symmetry of the vortex Hamiltonian. Disordering the quantum anomalous spin Hall state by Skyrmion condensation should produce a superconductor of an elementary charge 4e.Comment: 4+ pages, one table, one figure; (v2) improved pedagogy, new expression for the Pontryagin index derived, additional explanations; (v3) new and updated references, minor typos corrected, published versio

    Gemifloxacin use in the treatment of acute bacterial exacerbation of chronic bronchitis

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    The newest generation of fluoroquinolones have proven efficacy against bacterial organisms associated with acute exacerbation of chronic bronchitis (AECB). Gemifloxacin, as one of the quinolones in this class, exhibits many of the pharmacokinetic and pharmacodynamic characteristics of the class with a few notable differences. Against Streptococccus pneumoniae it has a lower minimal inhibitory concentration (MIC) than the other respiratory fluoroquinolones and it has activity against both bacterial DNA gyrase and topoisomerase IV. The increased activity of gemifloxacin against both enzymes may be associated with decreased rates of resistance. Clinically, gemifloxacin has been shown to have positive effects on length of hospitalization and increased success at long-term follow-up in AECB patients. These associations were observed in noninferiority comparison studies. Although an advantage with the use of gemifloxacin in AECB is suggested, there are no comparison data is available to conclude that gemifloxacin is superior to the other respiratory fluoroquinolones. Gemifloxacin is generally well tolerated, but is associated with a characteristic rash and gastrointestinal upset as its most common observed side effects

    Supersymmetric Runge-Lenz-Pauli vector for Dirac vortex in topological insulators and graphene

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    The Dirac mass-vortex at the surface of a topological insulator or in graphene is considered. Within the linear approximation for the vortex amplitude's radial dependence, the spectrum is a series of degenerate bound states, which can be classified by a set of accidental SU(2) and supersymmetry generators (I. F. Herbut and C.-K. Lu, Phys. Rev. B 83 125412 (2011)). Here we discuss further the properties and manifestations of the supersymmetry of the vortex Hamiltonian, and point out some interesting analogies to the Runge-Lenz-Pauli vector in the non-relativistic hydrogen atom. Symmetry breaking effects due to a finite chemical potential, and the Zeeman field are also analyzed. We find that a residual accidental degeneracy remains only in the special case of equal magnitudes of both terms, whereas otherwise it becomes removed entirely.Comment: revised version with added reference and a new paragraph on interpretation of two-velocity Weyl fermions realized in 2D optical lattice; to appear in J Phys

    Professional newsletter production : the case of community economic development newsletter

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    The Community Economic Development Newsletter is one of the projects undertaken by students of the MSc CED Programme. It involves collecting articles, looking for printers, producing the newsletter, and carrying out a survey to get information for improving the newsletter and finally writing a final report. This final report of the Community Economic Development Newsletter covers the period from September 2003 to March 2005. The report is divided into five chapters. Chapter one deals with, among others, the background to the study, vision, mission and objectives of the CED Newsletter, activities in the Newsletter project, various challenges and the assignment. Chapter two is concerned with literature review. It discusses an overview of the evolution of newsletters including newsletter production process concentrating on best practices. The chapter also discusses how to write an editorial column and also includes a section on empirical review that highlights various experiences from people who have been dealing with newsletter production. This chapter ends with a review of CED newsletter related policies with a view of finding what they say about community economic development. Chapter three is a discussion of research methodology used in this study, sampling techniques, data collection and analysis. Chapter four focuses on research findings and recommendations. The major findings of the study generally indicate that the CED Newsletter is a useful tool for promoting Community Economic Development and it is good in educating people about community economic development. Another finding is that, students would like to be associated with the newsletter even after graduating by contributing articles and receiving copies of the newsletter. Major recommendations include; the need of involving students, NGOs and government institutions in contributing articles, which discuss issues related to their projects. This chapter also discusses findings and recommendations on various issues of the Newsletter such as sale of the Newsletter, impression of readers on the Newsletter, relevance of the articles, reader friendliness, shortcomings in the Newsletter and interest in contributing articles and receiving the newsletter. There are also recommendations to facilitate continuity of the newsletter by the next Newsletter group. Chapter five contains highlights on the implementation of the recommendations. These include, taking on board all the possible recommendations and professional guidance, improving the design of the front page, having more articles from students and alumni that are up to date and well selected. (Author abstract)Hassan, S. S., Mnzava, R. A. D., Muthoni, C. W., Mvugalo, R., Sangana, G. P. (2005). Professional newsletter production: the case of community economic development newsletter. Retrieved from http://academicarchive.snhu.eduMaster of Science (M.S.)School of Community Economic Developmen

    Depression Among Type 2 Diabetes Rural Appalachian Clinic Attendees

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    The prevalence and impact of type 2 diabetes in Appalachia is understudied despite the presence of high-risk socioeconomic conditions (e.g., low levels of education and income). Appalachian counties experience greater burdens of poverty, income inequality, unemployment (1), and diabetes compared with non-Appalachian counties (2–5). Rates of comorbid depression have not been documented in this region. Patients with type 2 diabetes are two times more likely to experience depressive symptoms than their peers without diabetes (6). Depression prevalence in studies using self-report depression inventories was found to be 32.9%, with lower rates (28.5%) observed in studies using diagnostic interview schedules (6,7). Depressive symptoms are associated with worsened blood glucose levels (8), diabetes complications (9), increased functional disability (10), worsened adherence to diabetes regimen (11), higher ambulatory care costs (12), and increased mortality (13). The current study was conducted to identify rates of self-reported depression and to identify the socioeconomic and medical correlates of depression among type 2 diabetic patients attending family medicine and endocrinology appointments from rural Appalachian counties of southeastern Ohio and West Virginia. It was hypothesized that poverty would increase the risk of comorbid depression in this region

    Effect ofMTHFR genotypes and hyperhomocysteinemia on patient and graft survival in kidney transplant recipients

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    Effect ofMTHFRgenotypes and hyperhomocysteinemia on patient and graft survival in kidney transplant recipients.BackgroundThe total homocysteine (tHcy) plasma level, which is partly determined by theMTHFR 677C→T genotype, may be associated with vascular disease. We prospectively examined the influence ofMTHFR genotypes (677C→T, 1298A→C) and tHcy plasma concentration on all cause mortality and graft outcomes of renal transplant recipients.MethodsBaseline tHcy plasma levels of 189 patients (three groups with either theMTHFR 677CC, CT or TT genotype, including 63 patients in each group, were matched for age, gender, body mass index and creatinine clearance at baseline), were obtained between September 1996 and May 1997. Follow-up data (time until return to dialysis therapy, time and cause of death) were collected from April to June 1999. Kaplan-Meier survival estimations were calculated and plotted, the groups (threeMTHFR 677C→T genotype groups, or threeMTHFR 1298A→C genotype groups, or two groups with tHcy plasma levels above/below 15 μmol/L) were compared by log-rank test. Age, gender, body mass index (BMI), time since transplantation, serum creatinine, creatinine clearance, combinedMTHFR 677C→T/1298A→C genotypes, tHcy, folate and vitamin B12 plasma levels were evaluated with regard to graft and patient survival in a multivariate Cox-proportional hazard regression model.ResultsDuring the follow-up period of 2.26 ± 0.66 years, 9 patients died (5 in the TT, 2 in the CT and 2 in the CC genotype group;P = 0.34) and 22 returned to dialysis treatment (7 in the TT, 9 in the CT and 6 in the CC genotype group;P = 0.65). There was also no influnce ofMTHFR 1298A→C genotypes (AA genotype, 114 patients; AC genotype, 64 patients; CC genotype, 11 patients) on patient or graft survival (P = 0.7087 andP = 0.1633, respectively). Two of 93 patients with a tHcy plasma level ≤15 μmol/L died, in contrast to 7 of 96 patients in the low tHcy > 15 μmol/L group,P = 0.0778. Two patients in the low tHcy group had to return to dialysis, in contrast to 20 patients in the high tHcy group (P = 0.0001). In the multivariate model there was no significant predictor of patient survival, and the serum creatinine was the only predictor of graft survival (P < 0.0001).ConclusionsIn summary, our study shows that neitherMTHFR 677C→T/1298A→C genotypes nor hyperhomocysteinemia are independently associated with patient or graft survival following kidney transplantation

    Does lumbar spinal degeneration begin with the anterior structures? A study of the observed epidemiology in a community-based population

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    <p>Abstract</p> <p>Background-</p> <p>Prior studies that have concluded that disk degeneration uniformly precedes facet degeneration have been based on convenience samples of individuals with low back pain. We conducted a study to examine whether the view that spinal degeneration begins with the anterior spinal structures is supported by epidemiologic observations of degeneration in a community-based population.</p> <p>Methods-</p> <p>361 participants from the Framingham Heart Study were included in this study. The prevalences of anterior vertebral structure degeneration (disk height loss) and posterior vertebral structure degeneration (facet joint osteoarthritis) were characterized by CT imaging. The cohort was divided into the structural subgroups of participants with 1) no degeneration, 2) isolated anterior degeneration (without posterior degeneration), 3) combined anterior and posterior degeneration, and 4) isolated posterior degeneration (without anterior structure degeneration). We determined the prevalence of each degeneration pattern by age group < 45, 45-54, 55-64, ≥65. In multivariate analyses we examined the association between disk height loss and the response variable of facet joint osteoarthritis, while adjusting for age, sex, BMI, and smoking.</p> <p>Results-</p> <p>As the prevalence of the no degeneration and isolated anterior degeneration patterns decreased with increasing age group, the prevalence of the combined anterior/posterior degeneration pattern increased. 22% of individuals demonstrated isolated posterior degeneration, without an increase in prevalence by age group. Isolated posterior degeneration was most common at the L5-S1 and L4-L5 spinal levels. In multivariate analyses, disk height loss was independently associated with facet joint osteoarthritis, as were increased age (years), female sex, and increased BMI (kg/m<sup>2</sup>), but not smoking.</p> <p>Conclusions-</p> <p>The observed epidemiology of lumbar spinal degeneration in the community-based population is consistent with an ordered progression beginning in the anterior structures, for the majority of individuals. However, some individuals demonstrate atypical patterns of degeneration, beginning in the posterior joints. Increased age and BMI, and female sex may be related to the occurrence of isolated posterior degeneration in these individuals.</p

    Diagnostic Value of Lumbar Facet Joint Injection: A Prospective Triple Cross-Over Study

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    The diagnosis “lumbar facet syndrome” is common and often indicates severe lumbar spine surgery procedures. It is doubtful whether a painful facet joint (FJ) can be identified by a single FJ block. The aim of this study was to clarify the validity of a single and placebo controlled bilateral FJ blocks using local anesthetics. A prospective single blinded triple cross-over study was performed. 60 patients (31 f, 29 m, mean age 53.2 yrs (22–73)) with chronic low back pain (mean pain persistance 31 months, 6 months of conservative treatment without success) admitted to a local orthopaedic department for surgical or conservative therapy of chronic LBP, were included in the study. Effect on pain reduction (10 point rating scale) was measured. The 60 subjects were divided into six groups with three defined sequences of fluoroscopically guided bilateral monosegmental lumbar FJ test injections in “oblique needle” technique: verum-(local anaesthetic-), placebo-(sodium chloride-) and sham-injection. Carry-over and periodic effects were evaluated and a descriptive and statistical analysis regarding the effectiveness, difference and equality of the FJ injections and the different responses was performed. The results show a high rate of non-response, which documents the lack of reliable and valid predictors for a positive response towards FJ blocks. There was a high rate of placebo reactions noted, including subjects who previously or later reacted positively to verum injections. Equivalence was shown among verum vs. placebo and partly vs. sham also. With regard to test validity criteria, a single intraarticular FJ block with local anesthetics is not useful to detect the pain-responsible FJ and therefore is no valid and reliable diagostic tool to specify indication of lumbar spine surgery. Comparative FJ blocks with local anesthetics and placebo-controls have to be interpretated carefully also, because they solely give no proper diagnosis on FJ being main pain generator

    Macrolides for chronic asthma.

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    BACKGROUND: Asthma is a chronic disease in which inflammation of the airways causes symptomatic coughing, wheezing, and difficult breathing. The inflammation may have different underlying causes, including a reaction to infection in the lungs. Macrolides are antibiotics with antimicrobial and antiinflammatory activities that have been used long-term to control asthma symptoms. OBJECTIVES: To assess the effects of macrolides for managing chronic asthma. SEARCH METHODS: We searched the Cochrane Airways Group Specialised Register up to April 2015. We also manually searched bibliographies of previously published reviews and conference proceedings and contacted study authors. We included records published in any language in the search. SELECTION CRITERIA: Randomised controlled clinical trials involving both children and adults with chronic asthma treated with macrolides versus placebo for more than four weeks . DATA COLLECTION AND ANALYSIS: Two reviewers independently examined all records identified in the searches then reviewed the full text of all potentially relevant articles before extracting data in duplicate from all included studies. MAIN RESULTS: Twenty-three studies met the inclusion criteria, randomising a total of 1513 participants to receive macrolide or placebo. The quality of evidence was generally very low due to incomplete reporting of study methodology and clinical data, suspected publication bias, indirectness of study populations, risk of bias and imprecision (because of small numbers of patients and events). Most of the included studies reported data from patients with persistent or severe asthma, but inclusion criteria, interventions and outcomes were highly variable.Macrolides were not found to be better than placebo for the majority of clinical outcomes including exacerbations requiring hospital admission (odds ratio (OR) 0.98, 95% confidence interval (CI) 0.13 to 7.23; participants = 143; studies = 2; I(2) = 0%) or at least treatment with oral steroids (OR 0.82, 95% CI 0.43 to 1.57; participants = 290; studies = 5; I(2) = 0%). The evidence on symptom scales (standard mean difference (SMD) -0.04, 95% CI -0.36 to 0.28), asthma control (SMD -0.05, 95% CI -0.26 to 0.15), quality of life (mean difference (MD) 0.06, 95% CI -0.12 to 0.24) and rescue medication use (MD -0.26, 95% CI -0.65 to 0.12) was all of very low quality and did not show a benefit of macrolide treatment. There was some evidence that macrolides led to some improvement in lung function (forced expiratory volume in one second (FEV1): MD 0.08, 95% CI 0.02 to 0.14), although not on all the measures we assessed. Measures of bronchial hyperresponsiveness were too varied to pool, but most studies showed no clear benefit of macrolide over placebo. Two studies recruiting people taking regular oral corticosteroids suggested macrolides may have a steroid-sparing effect in this population. Macrolides were well tolerated with respect to severe adverse events, although less than half of the studies reported the outcome (OR 0.80, 95% CI 0.24 to 2.68; participants = 434; studies = 7; I(2) = 0%). Reporting of specific side effects was too patchy across studies to analyse meaningfully. As already reported in the previous versions of the systematic review, biomarkers of asthma activity, such as sputum and serum level of eosinophil cationic protein (ECP) or sputum and serum eosinophils, were lower in patients treated with macrolides, but this was not associated with clinical benefits.Two within-study subgroup analyses showed a possible benefit of macrolides for non-eosinophilic asthma, but it was not possible to investigate this further using the data available for this review. AUTHORS' CONCLUSIONS: Existing evidence does not show macrolides to be better than placebo for the majority of clinical outcomes. However, they may have a benefit on some measures of lung function, and we cannot rule out the possibility of other benefits or harms because the evidence is of very low quality due to heterogeneity among patients and interventions, imprecision and reporting biases.The review highlights the need for researchers to report clinically relevant outcomes accurately and completely using guideline definitions of exacerbations and validated scales. The possible benefit of macrolides in patients with non-eosinophilic asthma based on subgroup analyses in two of the included studies may require further investigation
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