160 research outputs found

    Effective Holographic Theories for low-temperature condensed matter systems

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    The IR dynamics of effective holographic theories capturing the interplay between charge density and the leading relevant scalar operator at strong coupling are analyzed. Such theories are parameterized by two real exponents (γ,δ)(\gamma,\delta) that control the IR dynamics. By studying the thermodynamics, spectra and conductivities of several classes of charged dilatonic black hole solutions that include the charge density back reaction fully, the landscape of such theories in view of condensed matter applications is characterized. Several regions of the (γ,δ)(\gamma,\delta) plane can be excluded as the extremal solutions have unacceptable singularities. The classical solutions have generically zero entropy at zero temperature, except when γ=δ\gamma=\delta where the entropy at extremality is finite. The general scaling of DC resistivity with temperature at low temperature, and AC conductivity at low frequency and temperature across the whole (γ,δ)(\gamma,\delta) plane, is found. There is a codimension-one region where the DC resistivity is linear in the temperature. For massive carriers, it is shown that when the scalar operator is not the dilaton, the DC resistivity scales as the heat capacity (and entropy) for planar (3d) systems. Regions are identified where the theory at finite density is a Mott-like insulator at T=0. We also find that at low enough temperatures the entropy due to the charge carriers is generically larger than at zero charge density.Comment: (v3): Added discussion on the UV completion of the solutions, and on extremal spectra in the charged case. Expanded discusion on insulating extremal solutions. Many other refinements and corrections. 126 pages. 48 figure

    Cardiac Transcription Factor Nkx2.5 Is Downregulated under Excessive O-GlcNAcylation Condition

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    Post-translational modification of proteins with O-linked N-acetylglucosamine (O-GlcNAc) is linked the development of diabetic cardiomyopathy. We investigated whether Nkx2.5 protein, a cardiac transcription factor, is regulated by O-GlcNAc. Recombinant Nkx2.5 (myc-Nkx2.5) proteins were reduced by treatment with the O-GlcNAcase inhibitors STZ and O-(2-acetamido-2-deoxy-D-glucopyroanosylidene)-amino-N-phenylcarbamate; PUGNAC) as well as the overexpression of recombinant O-GlcNAc transferase (OGT-flag). Co-immunoprecipitation analysis revealed that myc-Nkx2.5 and OGT-flag proteins interacted and myc-Nkx2.5 proteins were modified by O-GlcNAc. In addition, Nkx2.5 proteins were reduced in the heart tissue of streptozotocin (STZ)-induced diabetic mice and O-GlcNAc modification of Nkx2.5 protein increased in diabetic heart tissue compared with non-diabetic heart. Thus, excessive O-GlcNAcylation causes downregulation of Nkx2.5, which may be an underlying contributing factor for the development of diabetic cardiomyopathy

    Efficacies of the new Paclitaxel-eluting Coroflex Please™ Stent in percutaneous coronary intervention; comparison of efficacy between Coroflex Please™ and Taxus™ (ECO-PLEASANT) trial: study rationale and design

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    <p>Abstract</p> <p>Background</p> <p>Previous randomized trials have showed the superiority of Paclitaxel-eluting stent over bare metal stent in angiographic and clinical outcomes. Coroflex Please™ stent is a newly developed drug eluting stent using the Coroflex™ stent platform combined with the drug paclitaxel contained in a polymer coating. PECOPS I trial, one-arm observational study, showed that the clinical and angiographic outcomes of Coroflex Please™ stent were within the range of those of Taxus, the 1<sup>st </sup>generation paclitaxel-eluting stent (PES). However, there have been no studies directly comparing the Coroflex Please™ stent with the Taxus Liberte™ stent that is the newest version of Taxus. Therefore, prospective, randomized trial is required to demonstrate the non-inferiority of Coroflex Please™ stent compared with Taxus Liberte™ stent in a head-to-head manner.</p> <p>Methods</p> <p>In the comparison of Efficacy between COroflex PLEASe™ ANd Taxus™ stent(ECO-PLEASANT) trial, approximately 900 patients are being prospectively and randomly assigned to the either type of Coroflex Please™ stent and Taxus Liberte™ stent via web-based randomization. The primary endpoint is clinically driven target vessel revascularization at 9 months. The secondary endpoints include major cardiac adverse events, target vessel failure, stent thrombosis and angiographic efficacy endpoints.</p> <p>Discussion</p> <p>The ECO-PLEASANT trial is the study not yet performed to directly compare the efficacy and safety of the Coroflex Please™ versus Taxus Liberte™ stent. On the basis of this trial, we will be able to find out whether the Coroflex Please™ stent is non-inferior to Taxus Liberte™ stent or not.</p> <p>Trial registration</p> <p>ClinicalTrials.gov number, NCT00699543.</p

    5-dim Superconformal Index with Enhanced En Global Symmetry

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    The five-dimensional N=1\mathcal{N}=1 supersymmetric gauge theory with Sp(N) gauge group and SO(2N_f) flavor symmetry describes the physics on N D4-branes with NfN_f D8-branes on top of a single O8 orientifold plane in Type I' theory. This theory is known to be superconformal at the strong coupling limit with the enhanced global symmetry ENf+1E_{N_f+1} for Nf7N_f\le 7. In this work we calculate the superconformal index on S1×S4S^1\times S^4 for the Sp(1) gauge theory by the localization method and confirm such enhancement of the global symmetry at the superconformal limit for Nf5N_f\le 5 to a few leading orders in the chemical potential. Both perturbative and (anti)instanton contributions are present in this calculation. For Nf=6,7N_f=6,7 cases some issues related the pole structure of the instanton calculation could not be resolved and here we could provide only some suggestive answer for the leading contributions to the index. For the Sp(N) case, similar issues related to the pole structure appear.Comment: 70 pages, references added, published versio

    Viral population estimation using pyrosequencing

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    The diversity of virus populations within single infected hosts presents a major difficulty for the natural immune response as well as for vaccine design and antiviral drug therapy. Recently developed pyrophosphate based sequencing technologies (pyrosequencing) can be used for quantifying this diversity by ultra-deep sequencing of virus samples. We present computational methods for the analysis of such sequence data and apply these techniques to pyrosequencing data obtained from HIV populations within patients harboring drug resistant virus strains. Our main result is the estimation of the population structure of the sample from the pyrosequencing reads. This inference is based on a statistical approach to error correction, followed by a combinatorial algorithm for constructing a minimal set of haplotypes that explain the data. Using this set of explaining haplotypes, we apply a statistical model to infer the frequencies of the haplotypes in the population via an EM algorithm. We demonstrate that pyrosequencing reads allow for effective population reconstruction by extensive simulations and by comparison to 165 sequences obtained directly from clonal sequencing of four independent, diverse HIV populations. Thus, pyrosequencing can be used for cost-effective estimation of the structure of virus populations, promising new insights into viral evolutionary dynamics and disease control strategies.Comment: 23 pages, 13 figure

    Why do women not use antenatal services in low and middle income countries? A metasynthesis of qualitative studies

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    Background: Almost 50% of women in low & middle income countries (LMIC’s) don’t receive adequate antenatal care. Women’s views can offer important insights into this problem. Qualitative studies exploring inadequate use of antenatal services have been undertaken in a range of countries, but the findings are not easily transferable. We aimed to inform the development of future antenatal care programmes through a synthesis of findings in all relevant qualitative studies. Methods and Findings: Using a pre-determined search strategy, we identified robust qualitative studies reporting on the views and experiences of women in LMIC’s who received inadequate antenatal care. We used meta-ethnographic techniques to generate themes and a line of argument synthesis. We derived policy relevant hypotheses from the findings. We included 21 papers representing the views of more than 1230 women from 15 countries. Three key themes were identified: ‘Pregnancy as socially risky and physiologically healthy’; ‘Resource use and survival in conditions of extreme poverty’and ‘Not getting it right first time’. The line of argument synthesis describes a dissonance between programme design and cultural contexts that may restrict access and discourage return visits. We hypothesize that centralized, risk-focused antenatal care programmes may be at odds with the resources, beliefs and experiences of pregnant women who underuse antenatal services. Conclusions: Our findings suggest that there may be a mis-alignment between current antenatal provision and the social and cultural context of some women in LMIC’s. Antenatal care provision that is theoretically and contextually at odds with local contextual beliefs and experiences are likely to be underused, especially when attendance generates increased personal risks of lost family resource or physical danger during travel; when the promised care is not delivered due to resource constraints; and when women experience covert or overt abuse in care settings

    The 'Harmonizing Optimal Strategy for Treatment of coronary artery stenosis - sAfety & effectiveneSS of drug-elUting stents & antiplatelet REgimen' (HOST-ASSURE) trial: study protocol for a randomized controlled trial

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    <p>Abstract</p> <p>Background</p> <p>Second-generation drug-eluting stents (DES) have raised the bar of clinical performance. These stents are mostly made from cobalt chromium alloy. A newer generation DES has been developed from platinum chromium alloy, but clinical data regarding the efficacy and safety of the platinum chromium-based everolimus-eluting stent (PtCr-EES) is limited, with no comparison data against the cobalt chromium-based zotarolimus-eluting stent (CoCr-ZES). In addition, an antiplatelet regimen is an integral component of medical therapy after percutaneous coronary intervention (PCI). A 1-week duration of doubling the dose of clopidogrel (double-dose antiplatelet therapy (DDAT)) was shown to improve outcome at 1 month compared with conventional dose in acute coronary syndrome (ACS) patients undergoing PCI. However in Asia, including Korea, the addition of cilostazol (triplet antiplatelet therapy (TAT)) is used more commonly than doubling the dose of clopidogrel in high-risk patients.</p> <p>Methods</p> <p>In the 'Harmonizing Optimal Strategy for Treatment of coronary artery stenosis - sAfety & effectiveneSS of drug-elUting stents & antiplatelet REgimen' (HOST-ASSURE) trial, approximately 3,750 patients are being prospectively and randomly assigned in a 2 × 2 factorial design according to the type of stent (PtCr-EES vs CoCr-ZES) and antiplatelet regimen (TAT vs DDAT). The first primary endpoint is target lesion failure at 1 year for the stent comparison, and the second primary endpoint is net clinical outcome at 1 month for comparison of antiplatelet therapy regimen.</p> <p>Discussion</p> <p>The HOST-ASSURE trial is the largest study yet performed to directly compare the efficacy and safety of the PtCr-EES versus CoCr-ZES in an 'all-comers' population. In addition, this study will also compare the clinical outcome of TAT versus DDAT for 1-month post PCI.</p> <p>Trial registration</p> <p>ClincalTrials.gov number <a href="http://www.clinicaltrials.gov/ct2/show/NCT01267734">NCT01267734</a>.</p

    Risk factors for bone mineral density at the calcaneus in 40–59 year-old male workers: A cross-sectional study in Korea

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    <p>Abstract</p> <p>Background</p> <p>Few epidemiologic studies have attempted to investigate the prevalence and risk factors for osteopenia and osteoporosis in middle-aged Asian men. We performed this study to determine the prevalence and risk factors of osteopenia and osteoporosis in this population.</p> <p>Methods</p> <p>This cross-sectional study was conducted from March to July, 2004. The subjects were 2,073 males aged from 40 to 59 years in the KHNP (Korea Hydro & Nuclear Power) workplace-based cohort. Bone mineral density (BMD) was measured by peripheral, dual-energy, X-ray absorptiometry (DXA) at the calcaneus. Anthropometric and lifestyle factors were investigated using a standard, self-reported questionnaire.</p> <p>Results</p> <p>BMD was 0.60 ± 0.09 g/cm<sup>2 </sup>(mean ± standard deviation) and was negatively correlated with age (r = -0.18, <it>P </it>< 0.001), but positively correlated with waist-to-hip ratio (WHR; r = 0.15, <it>P </it>< 0.001), body fat (r = 0.10, <it>P </it>< 0.001), BMI (r = 0.35, <it>P </it>< 0.001), height (r = 0.26, <it>P </it>< 0.001), and weight (r = 0.43, <it>P </it>< 0.001).</p> <p>In multiple linear regression analysis, the independent determinants associated with BMD were increasing age (coefficient = -0.002, <it>P </it>< 0.001), physical activity (≤ 2/week vs. ≥ 3/week; coefficient = 0.017, <it>P </it>< 0.001), WHR (coefficient = -0.796, <it>P </it>< 0.001), body mass index (BMI; coefficient = 0.023, <it>P </it>< 0.001) and smoking status (never vs. ever; coefficient = -0.018, <it>P </it>< 0.001).</p> <p>Conclusion</p> <p>We suggest that BMD of the calcaneus is correlated negatively with exposure to smoke and increased WHR, but positively with regular exercise and increased BMI.</p
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