504 research outputs found

    Development of a Global Model for the Analysis of Plasma in an Atmosphere-Breathing Cathode-Less Thruster

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    This study investigates the preliminary propulsive performances of a cathode-less plasma thruster with air as its propellant. The analysis is carried out through a global model and simulates a thruster over a power range of 0 to 50 W. The developed code considers a set of 177 chemical reactions involving 8 different species and includes empirical equations to account for electronegative effects. The analysis presents the steady-state values of species densities at 10 W, 30 W, and 50 W to gain insights into the key characteristics of plasma dynamics. Moreover, the study estimates the thrust and specific impulse and compares the results to data from models that employ xenon and iodine, aiming to understand the performances of air in low-power thrusters. Lastly, the study examines the effects of varying air inflow concentration on the chemistry, analyzing three different orbit altitudes (i.e., 200, 300, and 400 km)

    Retreatment with pegylated interferon plus ribavirin of chronic hepatitis C non-responders to interferon plus ribavirin: A meta-analysis.

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    BACKGROUND/AIMS: Efficacy of retreatment with pegylated interferon (PEG-IFN) plus ribavirin of non-responders to standard or pegylated IFN plus ribavirin has been assessed in various studies, but sustained virologic response (SVR) rates are variable and factors influencing efficacy and tolerability still remain incompletely defined. We aimed to focus on SVR rates and to identify factors influencing them in this meta-analysis. METHODS: MEDLINE as well as a manual search were used. Studies were included if they were controlled or uncontrolled trials, if they had been published as full-length papers and if they included non-responders to standard or pegylated IFN and ribavirin therapy. Fourteen trials were included in the meta-analysis. Data on study populations, interventions, and outcomes were extracted from trials using a random-effects model. Primary outcome was the SVR rate. RESULTS: The pooled estimate of SVR rate was 16.3% (95% Confidence Interval - 95% CI, 8.3-29.6%). There was a significant heterogeneity among studies (p<0.0001). Heterogeneity was less apparent in studies that included fewer patients with cirrhosis or overweight. By meta-regression, higher SVR rate was observed in trials with a lower prevalence of subjects with genotype 1 infection and with fewer overweight patients. The use of a 24-week retreatment stopping rule did not affect SVR rate. CONCLUSIONS: The overall modest efficacy argues against an indiscriminate retreatment with PEG-IFN and ribavirin of all non-responders. Restricting retreatment to non-overweight patients or to those with genotype 2 or 3 infection, using a 24-week retreatment stopping rule, would optimize the potential benefit with a scarce likelihood of missing a curative response

    On a Fast Solution Strategy for a Surface-Wire Integral Formulation of the Anisotropic Forward Problem in Electroencephalography

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    This work focuses on a quasi-linear-in-complexity strategy for a hybrid surface-wire integral equation solver for the electroencephalography forward problem. The scheme exploits a block diagonally dominant structure of the wire self block— that models the neuronal fibers self interactions—and of the surface self block—modeling interface potentials. This structure leads to two Neumann iteration schemes further accelerated with adaptive integral methods. The resulting algorithm is linear up to logarithmic factors. Numerical results confirm the performance of the method in biomedically relevant scenarios

    Identification of na\uefve HCV-1 patients with chronic hepatitis who may benefit from dual therapy with peg-interferon and ribavirin

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    Background & Aims The pool of HCV genotype 1 patients likely to be cured by peg-interferon and ribavirin remains to be quantified. Methods In 1045 patients treated with peg-interferon and ribavirin, two therapeutic strategies were confronted: the first one evaluated only baseline variables associated with sustained virological response (SVR), and the second one included the rapid virologic response (RVR) in addition to baseline predictors. An 80% SVR rate was the threshold to retain a strategy as clinically relevant. Results Overall, 414 patients (39.6%) attained SVR. In the first strategy, the hierarchy of features independently associated with SVR was IL28B CC genotype (OR 5.082; CI 3.637-7.101), low (80% SVR threshold. Only 26.6% of no-RVR patients attained SVR. Among the 255 RVR patients, the likelihood of SVR was 61.8% in those with unfavorable predictors, 80% in the presence of a single predictor, and 100% when both predictors were present. By using this model, 200 patients (19.1%) were predicted to have an 80% chance of being cured with dual therapy. Conclusions A consistent subset of na\uefve HCV-1 patients, identified by some baseline characteristics and RVR, may benefit from dual treatment with peg-interferon and ribavirin. \ua9 2013 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved

    Ampere Hour as a Predictor of Cardiac Resynchronization Defibrillator Pulse Generator Battery Longevity: A Multicenter Study

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122444/1/pace12831_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122444/2/pace12831.pd

    Revised theory of transient mass fluctuations

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    Abstract Several publications during the last 10 years by Woodward and colleagues have indicated a theory, based on general relativity, that has: (1) predicted transient mass fluctuations; (2) cited a specific embodiments where a net average force would be present; (3) suggested a few ways that this theory might be tested in the laboratory; and (4) have reported such test results incorporating these embodiments. In this paper we show that: (1) the average force predicted by Woodward occurred only because of a neglected term in a product derivative, and that when the neglected term is correctly returned, the average force vanishes; (2) this vanishment of the average force occurs for arbitrary forcing functions, not just the sinusoidal one considered by Woodward; (3) the transient mass fluctuation, predicted by Woodward, was developed in a theory which neglected local gravitational and electrodynamic forces which are several dozen orders of magnitude greater; (4) a less incomplete theory considering local gravitational forces produces a vastly smaller transient mass fluctuation

    A meta-analysis for the effect of prophylactic GTN on the incidence of post-ERCP pancreatitis and on the successful rate of cannulation of bile ducts

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    <p>Abstract</p> <p>Background</p> <p>Glyceryl trinitrate (GTN) has been shown to be able to relax the sphincter of Oddi (SO) both in animals and humans. Theoretically, the use of these compounds during and after endoscopic retrograde cholangiopancreatgraphy (ERCP) could relax the biliary and pancreatic sphincters, facilitating cannulation of common bile duct (CBD) during the procedure, or minimizing potential pancreatic outflow obstruction after the procedure. However, clinical trials evaluating the protective effect of GTN on the post-endoscopic retrograde cholangiopancreatgraphy pancreatitis (PEP) have yielded inconclusive results. This meta-analysis is to systematically assess the effect of prophylactic administration of glyceryl trinitrate (GTN) on the prevention of PEP and the effect on the cannulation of bile ducts.</p> <p>Methods</p> <p>By searching PubMed (1966 to September 2009), CENTRAL (Cochrane Controlled trials Register; issue 3, 2009) and EMBASE.com (1984 to September 2009), two independent reviewers systematically identified prospective randomized controlled trials (RCTs) detecting the effect of prophylactic GTN on the incidence of PEP and on the cannulation of bile ducts. A meta-analysis of these clinical trials was then performed.</p> <p>Results</p> <p>There are 55/899(6.1%) patients suffering PEP in the treatment group versus 95/915(10.4%) patients in the placebo group. The overall pooled risk of PEP was significantly lower in the GTN group than in the placebo group (OR 0.56, 95% CI: 0.40 to 0.79, p = 0.001). Subgroup analyses suggested that GTN administered by the sublingual form (OR 0.34,95% CI:0.16 to 0.75, p = 0.007) is more effective than transdermal route(OR 0.64,95% CI:0.40 to 1.01, p = 0.05), and the protective effect of GTN was far more obvious in the centers with high incidence of PEP (OR 0.40, 95% CI:0.24 to 0.67, p = 0.0006) than those centers with a low incidence of PEP (OR 0.75, 95% CI: 0.47 to 1.20, p = 0.22). Additionally, the meta-analysis suggests that GTN was not helpful for the cannulation of bile ducts.</p> <p>Conclusion</p> <p>We concluded that prophylactic administration of GTN may significantly reduce the incidence of PEP and not be helpful for the cannulation of bile ducts.</p

    Liver Parenchyma Perforation following Endoscopic Retrograde Cholangiopancreatography

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    Although endoscopic retrograde cholangiopancreatography (ERCP) is an effective modality for the diagnosis and treatment of biliary and pancreatic diseases, it is still related with several severe complications. We report on the case of a female patient who developed liver parenchyma perforation following ERCP. She underwent ERCP with sphincterotomy and extraction of a common bile duct stone. Shortly after ERCP, abdominal distension was identified. Abdominal computed tomography revealed intraabdominal air leakage and leakage of contrast dye penetrating the liver parenchyma into the space around the spleen. Since periampullary perforation related to sphincterotomy could not be denied, she was referred for immediate surgery. Obvious perforation could not be found at surgery. Cholecystectomy, insertion of a T tube into the common bile duct, placement of a duodenostomy tube and drainage of the retroperitoneum were performed. She did well postoperatively and was discharged home on postoperative day 28. In conclusion, as it is well recognized that perforation is one of the most serious complication related to ERCP, liver parenchyma perforation should be suspected as a cause
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