481 research outputs found

    Effects of Renal Denervation on Sympathetic Activation, Blood Pressure, and Glucose Metabolism in Patients with Resistant Hypertension

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    Increased central sympathetic drive is a hallmark of several important clinical conditions including essential hypertension, heart failure, chronic kidney disease, and insulin resistance. Afferent signaling from the kidneys has been identified as an important contributor to elevated central sympathetic drive and increased sympathetic outflow to the kidney and other organs is crucially involved in cardiovascular control. While the resultant effects on renal hemodynamic parameters, sodium and water retention, and renin release are particularly relevant for both acute and long term regulation of blood pressure, increased sympathetic outflow to other vascular beds may facilitate further adverse consequences of sustained sympathetic activation such as insulin resistance, which is commonly associated with hypertension. Recent clinical studies using catheter-based radiofrequency ablation technology to achieve functional renal denervation in patients with resistant hypertension have identified the renal nerves as therapeutic target and have helped to further expose the sympathetic link between hypertension and insulin resistance. Initial data from two clinical trials and several smaller mechanistic clinical studies indicate that this novel approach may indeed provide a safe and effective treatment alternative for resistant hypertension and some of its adverse consequences

    Change in Sympathetic Nerve Firing Pattern Associated with Dietary Weight Loss in the Metabolic Syndrome

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    Sympathetic activation in subjects with the metabolic syndrome (MS) plays a role in the pathogenesis of cardiovascular disease development. Diet-induced weight loss decreases sympathetic outflow. However the mechanisms that account for sympathetic inhibition are not known. We sought to provide a detailed description of the sympathetic response to diet by analyzing the firing behavior of single-unit sympathetic nerve fibers. Fourteen subjects (57 ± 2 years, nine men, five females) fulfilling ATP III criteria for the MS underwent a 3-month low calorie diet. Metabolic profile, hemodynamic parameters, and multi-unit and single-unit muscle sympathetic nerve activity (MSNA, microneurography) were assessed prior to and at the end of the diet. Patients’ weight dropped from 96 ± 4 to 88 ± 3 kg (P < 0.001). This was associated with a decrease in systolic and diastolic blood pressure (−12 ± 3 and −5 ± 2 mmHg, P < 0.05), and in heart rate (−7 ± 2 bpm, P < 0.01) and an improvement in all metabolic parameters (fasting glucose: −0.302.1 ± 0.118 mmol/l, total cholesterol: −0.564 ± 0.164 mmol/l, triglycerides: −0.414 ± 0.137 mmol/l, P < 0.05). Multi-unit MSNA decreased from 68 ± 4 to 59 ± 5 bursts/100 heartbeats (P < 0.05). Single-unit MSNA indicated that the firing rate of individual vasoconstrictor fibers decreased from 59 ± 10 to 32 ± 4 spikes/100 heart beats (P < 0.05). The probability of firing decreased from 34 ± 5 to 23 ± 3% of heartbeats (P < 0.05), and the incidence of multiple firing decreased from 14 ± 4 to 6 ± 1% of heartbeats (P < 0.05). Cardiac and sympathetic baroreflex function were significantly improved (cardiac slope: 6.57 ± 0.69 to 9.57 ± 1.20 ms·mmHg−1; sympathetic slope: −3.86 ± 0.34 to −5.05 ± 0.47 bursts/100 heartbeats·mmHg−1, P < 0.05 for both). Hypocaloric diet decreased sympathetic activity and improved hemodynamic and metabolic parameters. The sympathoinhibition associated with weight loss involves marked changes, not only in the rate but also in the firing pattern of active vasoconstrictive fibers

    11.1: Invited Paper : Advances in Blue Phosphorescent Organic Light‐Emitting Devices

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    This paper discusses the latest developments towards a commercial blue phosphorescent organic light emitting device (PHOLED™) technology. Progress towards achieving a high efficiency, long‐lived saturated blue PHOLED is discussed. First, a high efficiency (20% EQE, 45 cd/A), light blue (0.17, 0.39) PHOLED is presented. Next, long‐lived blue PHOLEDs having chromaticity co‐ordinates (0.17, 0.38) and (0.16, 0.29) are estimated to degrade to half their initial luminance of 200cd/m 2 after >100,000 hrs and 17,500 hrs, respectively. Finally, results from PHOLEDs designed to increase blue color saturation and lifetime are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92011/1/1.2433213.pd

    Interpolated wave functions for nonadiabatic simulations with the fixed-node quantum Monte Carlo method

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    Simulating nonadiabatic effects with many-body wave function approaches is an open field with many challenges. Recent interest has been driven by new algorithmic developments and improved theoretical understanding of properties unique to electron-ion wave functions. Fixed-node diffusion Monte Caro is one technique that has shown promising results for simulating electron-ion systems. In particular, we focus on the CH molecule for which previous results suggested a relatively significant contribution to the energy from nonadiabatic effects. We propose a new wave function ansatz for diatomic systems which involves interpolating the determinant coefficients calculated from configuration interaction methods. We find this to be an improvement beyond previous wave function forms that have been considered. The calculated nonadiabatic contribution to the energy in the CH molecule is reduced compared to our previous results, but still remains the largest among the molecules under consideration.Comment: 7 pages, 3 figure

    Computational Physics on Graphics Processing Units

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    The use of graphics processing units for scientific computations is an emerging strategy that can significantly speed up various different algorithms. In this review, we discuss advances made in the field of computational physics, focusing on classical molecular dynamics, and on quantum simulations for electronic structure calculations using the density functional theory, wave function techniques, and quantum field theory.Comment: Proceedings of the 11th International Conference, PARA 2012, Helsinki, Finland, June 10-13, 201

    Are Socioeconomic Benefits of Restoration Adequately Quantified? A Meta-analysis of Recent Papers (2000–2008) in Restoration Ecology and 12 Other Scientific Journals. Restoration Ecology

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    Many ecosystems have been transformed, or degraded by human use, and restoration offers an opportunity to recover services and benefits, not to mention intrinsic values. We assessed whether restoration scientists and practitioners use their projects to demonstrate the benefits restoration can provide in their peer-reviewed publications. We evaluated a sample of the academic literature to determine whether links are made explicit between ecological restoration, society, and public policy related to natural capital. We analyzed 1,582 peer-reviewed papers dealing with ecological restoration published between 1 January 2000 and 30 September 2008 in 13 leading scientific journals. As selection criterion, we considered papers that contained either “restoration” or “rehabilitation” in their title, abstract, or keywords. Furthermore, as one-third of the papers were published in Restoration Ecology, we used that journal as a reference for comparison with all the other journals. We readily acknowledge that aquatic ecosystems are under-represented, and that the largely inaccessible gray literature was ignored. Within these constraints, we found clear evidence that restoration practitioners are failing to signal links between ecological restoration, society, and policy, and are underselling the evidence of benefits of restoration as a worthwhile investment for society. We discuss this assertion and illustrate it with samples of our findings—with regards to (1) the geographical and institutional affiliations of authors; (2) the choice of ecosystems studied, methods employed, monitoring schemes applied, and the spatial scale of studies; and (3) weak links to payments for ecosystem service setups, agriculture, and ramifications for public policy.The authors thank the South African Water Research Commission which provided financial support for this study, under contract K5/1803, The impact of reestablishing indigenous plants and restoring the natural landscape on sustainable rural employment and land productivity through payment for environmental services, awarded to ASSET Research (Pretoria)
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