479 research outputs found

    Cyclotron Resonance in the Layered Perovskite Superconductor Sr2RuO4

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    We have measured the cyclotron masses in Sr2RuO4 through the observation of periodic-orbit-resonances - a magnetic resonance technique closely related to cyclotron resonance. We obtain values for the alpha, beta and gamma Fermi surfaces of (4.33+/-0.05)me, (5.81+/-0.03)me and (9.71+/-0.11)me respectively. The appreciable differences between these results and those obtained from de Haas- van Alphen measurements are attributable to strong electron-electron interactions in this system. Our findings appear to be consistent with predictions for a strongly interacting Fermi liquid; indeed, semi-quantitative agreement is obtained for the electron pockets beta and gamma.Comment: 4 pages + 3 figure

    Frustrated kinetic energy, the optical sum rule, and the mechanism of superconductivity

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    The theory that the change of the electronic kinetic energy in a direction perpendicular to the CuO-planes in high-temperature superconductors is a substantial fraction of the condensation energy is examined. It is argued that the consequences of this theory based on a rigorous cc-axis conductivity sum rule are consistent with recent optical and penetration depth measurements.Comment: 4 pages (RevTeX) and 2 eps figure

    The treatment of achalasia patients with esophageal varices: an international study

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    Background: Treatment options for achalasia include endoscopic and surgical techniques that carry the risk of esophageal bleeding and perforation. The rare coexistence of esophageal varices has only been anecdotally described and treatment is presumed to carry additional risk. Methods: Experience from physicians/surgeons treating this rare combination of disorders was sought through the International Manometry Working Group. Results: Fourteen patients with achalasia and varices from seven international centers were collected (mean age 61 9 years). Five patients were treated with botulinum toxin injections (BTI), four had dilation, three received peroral endoscopic myotomy (POEM), one had POEM then dilation, and one patient underwent BTI followed by Heller’s myotomy. Variceal eradication preceded achalasia treatment in three patients. All patients experienced a significant symptomatic improvement (median Eckardt score 7 vs 1; p < 0.0001) at 6 months follow-up, with treatment outcomes resembling those of 20 non- cirrhotic achalasia patients who underwent similar therapy. No patients had recorded complications of bleeding or perforation. Conclusion: This study shows an excellent short-term symptomatic response in patients with esophageal achalasia and varices and demonstrates that the therapeutic outcomes and complications, other than transient encephalopathy in both patients who had a portosystemic shunt, did not differ to disease-matched patients without varices

    Critical fluctuation conductivity in layered superconductors in strong electric field

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    The paraconductivity, originating from critical superconducting order-parameter fluctuations in the vicinity of the critical temperature in a layered superconductor is calculated in the frame of the self-consistent Hartree approximation, for an arbitrarily strong electric field and zero magnetic field. The paraconductivity diverges less steep towards the critical temperature in the Hartree approximation than in the Gaussian one and it shows a distinctly enhanced variation with the electric field. Our results indicate that high electric fields can be effectively used to suppress order-parameter fluctuations in high-temperature superconductors.Comment: 11 pages, 2 figures, to be published in Phys. Rev.

    Global longitudinal strain and biomarkers of cardiac damage and stress as predictors of outcomes after transcatheter aortic valve implantation

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    Background Global longitudinal strain (GLS) is a sensitive measure of left ventricular function and a risk marker in severe aortic stenosis. We sought to determine whether biomarkers of cardiac damage (cardiac troponin) and stress (NT-proBNP [N-terminal pro-B-type natriuretic peptide]) could complement GLS to identify patients with severe aortic stenosis at highest risk. Methods and Results From a multicenter prospective cohort of patients with symptomatic severe aortic stenosis who underwent transcatheter aortic valve implantation, we measured absolute GLS (aGLS), cardiac troponin, and NT-proBNP at baseline in 499 patients. Left ventricular ejection fraction \u3c50% was observed in 19% and impaired GLS (aGLS \u3c15%) in 38%. Elevations in cardiac troponin and NT-proBNP were present in 79% and 89% of those with impaired GLS, respectively, as compared with 63% and 60% of those with normal GLS, respectively

    Metabolic signatures of cardiac dysfunction, multimorbidity, and post-transcatheter aortic valve implantation death

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    Background Studies in mice and small patient subsets implicate metabolic dysfunction in cardiac remodeling in aortic stenosis, but no large comprehensive studies of human metabolism in aortic stenosis with long-term follow-up and characterization currently exist. Methods and Results Within a multicenter prospective cohort study, we used principal components analysis to summarize 12 echocardiographic measures of left ventricular structure and function pre-transcatheter aortic valve implantation in 519 subjects (derivation). We used least absolute shrinkage and selection operator regression across 221 metabolites to define metabolic signatures for each structural pattern and measured their relation to death and multimorbidity in the original cohort and up to 2 validation cohorts (N=543 for overall validation). In the derivation cohort (519 individuals; median age, 84 years, 45% women, 95% White individuals), we identified 3 axes of left ventricular remodeling, broadly specifying systolic function, diastolic function, and chamber volumes. Metabolite signatures of each axis specified both known and novel pathways in hypertrophy and cardiac dysfunction. Over a median of 3.1 years (205 deaths), a metabolite score for diastolic function was independently associated with post-transcatheter aortic valve implantation death (adjusted hazard ratio per 1 SD increase in score, 1.54 [95% CI, 1.25-1.90]

    Bioresponsive polymers for nanomedicine: expectations and reality!

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    Bioresponsive polymers in nanomedicine have been widely perceived to selectively activate the therapeutic function of nanomedicine at diseased or pathological sites, while sparing their healthy counterparts. This idea can be described as an advanced version of Paul Ehrlich's magic bullet concept. From that perspective, the inherent anomalies or malfunction of the pathological sites are generally targeted to allow the selective activation or sensory function of nanomedicine. Nonetheless, while the primary goals and expectations in developing bioresponsive polymers are to elicit exclusive selectivity of therapeutic action at diseased sites, this remains difficult to achieve in practice. Numerous research efforts have been undertaken, and are ongoing, to tackle this fine-tuning. This review provides a brief introduction to key stimuli with biological relevance commonly featured in the design of bioresponsive polymers, which serves as a platform for critical discussion, and identifies the gap between expectations and current reality.Drug Delivery Technolog

    Thermal Power Emission and Its Impact on Betel Vine (Piper betel): A Participatory Action Research in West Bengal

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    Thermal power stations are now considered as the foremost global concern as these are responsible to produce detrimental effects on the environment. Environmental Impact Assessment (EIA) is a process of evaluating the likely environmental impact so proposed project or development, taking into account inter-related socio-economic, cultural and human-health impacts, both beneficial and adverse. In this study, the perception of certain(60)farmers in 5 villages of Kolaghat block of Purba Medinipur, West Bengal, India are recorded and analyzed on the basis of their knowledge and views about thermal power, environment and about their individual enterprises. There are 10 independent variables-ages (x1), education (x2), family Member (x3), income (x4), homestead land (x5), total Land (x6), land under Boroj (x7), input cost (x8), and livestock number (x9), distance of villages from Kolaghat thermal power plant (x10) and 1 dependable variables- 1) perceived impacts of Kolaghat thermal power plant on betel vine(y2). From this empirical study, it has been found to be concluded that the common perception among the betel growers is that the Kolaghat thermal power plant produces huge amount of flu ash which reduces their level of income on betel vine. Thick layer of fly ash reduces the quality of leaves and bronzing occurred which affect production. It affects betel vine borojes. It is found from the result that villages which are nearly placed at Kolaghat thermal power plant side are mostly affected

    Evidence for the interaction of Endophilin A3 with endogenous K(Ca)2.3 channels in PC12 cells

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    Background/Aims: Small-conductance calcium-activated (SK) channels play an important role by controlling the after-hyperpolarization of excitable cells. The level of expression and density of these channels is an essential factor for controlling different cellular functions. Several studies showed a co-localization of KCa2.3 channels and Endophilin A3 in different tissues. Endophilin A3 belongs to a family of BAR- and SH3 domain containing proteins that bind to dynamin and are involved in the process of vesicle scission in clathrin-mediated endocytosis. Methods: Using the yeast two-hybrid system and the GST pull down assay we demonstrated that Endophilin A3 interacts with the N-terminal part of KCa2.3 channels. In addition, we studied the impact of this interaction on channel activity by patch clamp measurements in PC12 cells expressing endogenous KCa2.3 channels. KCa2.3 currents were activated by using pipette solutions containing 1 µM free Ca(2+). Results: Whole-cell measurements of PC12 cells transfected with Endophilin A3 showed a reduction of KCa2.3 specifc Cs(+) currents indicating that the interaction of Endophilin A3 with KCa2.3 channels also occurs in mammalian cells and that this interaction has functional consequences for current flowing through KCa2.3 channels. Since KCa2.3 specific currents could be increased in PC12 cells transfected with Endophilin A3 with DC-EBIO (30 µM), a known SK-channel activator, these data also implicate that Endophilin A3 did not significantly remove KCa2.3 channels from the membrane but changed the sensitivity of the channels to Ca(2+) which could be overcome by DC-EBIO. Conclusion: This interaction seems to be important for the function of KCa2.3 channels and might therefore play a significant role in situations where channel activation is pivotal for cellular function

    Trends in Prevalence of Advanced HIV Disease at Antiretroviral Therapy Enrollment - 10 Countries, 2004-2015.

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    Monitoring prevalence of advanced human immunodeficiency virus (HIV) disease (i.e., CD4+ T-cell count <200 cells/μL) among persons starting antiretroviral therapy (ART) is important to understand ART program outcomes, inform HIV prevention strategy, and forecast need for adjunctive therapies.*,†,§ To assess trends in prevalence of advanced disease at ART initiation in 10 high-burden countries during 2004-2015, records of 694,138 ART enrollees aged ≥15 years from 797 ART facilities were analyzed. Availability of national electronic medical record systems allowed up-to-date evaluation of trends in Haiti (2004-2015), Mozambique (2004-2014), and Namibia (2004-2012), where prevalence of advanced disease at ART initiation declined from 75% to 34% (p<0.001), 73% to 37% (p<0.001), and 80% to 41% (p<0.001), respectively. Significant declines in prevalence of advanced disease during 2004-2011 were observed in Nigeria, Swaziland, Uganda, Vietnam, and Zimbabwe. The encouraging declines in prevalence of advanced disease at ART enrollment are likely due to scale-up of testing and treatment services and ART-eligibility guidelines encouraging earlier ART initiation. However, in 2015, approximately a third of new ART patients still initiated ART with advanced HIV disease. To reduce prevalence of advanced disease at ART initiation, adoption of World Health Organization (WHO)-recommended "treat-all" guidelines and strategies to facilitate earlier HIV testing and treatment are needed to reduce HIV-related mortality and HIV incidence
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