404 research outputs found

    Tau functions as Widom constants

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    We define a tau function for a generic Riemann-Hilbert problem posed on a union of non-intersecting smooth closed curves with jump matrices analytic in their neighborhood. The tau function depends on parameters of the jumps and is expressed as the Fredholm determinant of an integral operator with block integrable kernel constructed in terms of elementary parametrices. Its logarithmic derivatives with respect to parameters are given by contour integrals involving these parametrices and the solution of the Riemann-Hilbert problem. In the case of one circle, the tau function coincides with Widom's determinant arising in the asymptotics of block Toeplitz matrices. Our construction gives the Jimbo-Miwa-Ueno tau function for Riemann-Hilbert problems of isomonodromic origin (Painlev\'e VI, V, III, Garnier system, etc) and the Sato-Segal-Wilson tau function for integrable hierarchies such as Gelfand-Dickey and Drinfeld-Sokolov.Comment: 26 pages, 6 figure

    Clinical Approach to the Standardization of Oriental Medical Diagnostic Pattern Identification in Stroke Patients

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    In Korea, many stroke patients receive oriental medical care, in which pattern-identification plays a major role. Pattern-identification is Oriental Medicine's unique diagnostic system. This study attempted to standardize oriental medical pattern-identification for stroke patients. This was a community-based multicenter study that enrolled stroke patients within 30 days after their ictus. We assessed the patients' general characteristics and symptoms related to pattern-identification. Each patient's pattern was determined when two doctors had the same opinion. To determine which variables affect the pattern-identification, binary logistic regression analysis was used with the backward method. A total of 806 stroke patients were enrolled. Among 480 patients who were identified as having a certain pattern, 100 patients exhibited the Fire Heat Pattern, 210 patients the Phlegm Dampness Pattern, nine patients the Blood Stasis Pattern, 110 patients the Qi Deficiency Pattern, and 51 patients the Yin Deficiency Pattern. After the regression analysis, the predictive logistic equations for the Fire Heat, Phlegm Dampness, Qi Deficiency, and Yin Deficiency patterns were determined. The Blood Stasis Pattern was omitted because the sample size was too small. Predictive logistic equations were suggested for four of the patterns. These criteria would be useful in determining each stroke patient's pattern in clinics. However, further studies with large samples are necessary to validate and confirm these criteria

    Defect states in hybrid solar cells consisting of Sb2S3 quantum dots and TiO2 nanoparticles

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    We have studied defect states in an organic-inorganic hybrid solar cell containing Sb2S3 quantum dots (QDs) and TiO2 nanoparticles (NPs) by using deep level transient spectroscopy (DLTS). An Au electrode was deposited as a Schottky contact on the sample, where the Sb2S3 QDs were distributed on the surface of TiO2 NPs by chemical synthesis. The activation energy and capture-cross section of an interface state between the Sb2S3 QDs and the TiO2 NPs were found to be about 0.78 eV and 2.21 x 10(-9) cm(-2), respectively. Also, the densities of this interface trap under a measurement voltage of -1 V were approximately 2.5 x 10(17) cm(-3). Based on these results, the interface trap was positioned around E-c - 1.03 eV below the conduction band edge of Sb2S3 QD. Thus, the external quantum efficiency of the solar cell was affected because of its role as a recombination center for carriers generated from Sb2S3 QDs. (C) 2013 AIP Publishing LLCclos

    Spatio-Temporal Variability of Aerosol Optical Depth, Total Ozone and NO(2)Over East Asia: Strategy for the Validation to the GEMS Scientific Products

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    In this study, the spatio-temporal variability of aerosol optical depth (AOD), total column ozone (TCO), and total column NO2(TCN) was identified over East Asia using long-term datasets from ground-based and satellite observations. Based on the statistical results, optimized spatio-temporal ranges for the validation study were determined with respect to the target materials. To determine both spatial and temporal ranges for the validation study, we confirmed that the observed datasets can be statistically considered as the same quantity within the ranges. Based on the thresholds of R-2>0.95 (temporal) and R>0.95 (spatial), the basic ranges for spatial and temporal scales for AOD validation was within 30 km and 30 min, respectively. Furthermore, the spatial scales for AOD validation showed seasonal variation, which expanded the range to 40 km in summer and autumn. Because of the seasonal change of latitudinal gradient of the TCO, the seasonal variation of the north-south range is a considerable point. For the TCO validation, the north-south range is varied from 0.87 degrees in spring to 1.05 degrees in summer. The spatio-temporal range for TCN validation was 20 min (temporal) and 20-50 km (spatial). However, the nearest value of satellite data was used in the validation because the spatio-temporal variation of TCN is large in summer and autumn. Estimation of the spatio-temporal variability for respective pollutants may contribute to improving the validation of satellite products

    Effects of Hyul-Bu-Chuke-Tang on Erythrocyte Deformability and Cerebrovascular CO2 Reactivity in Normal Subjects

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    Aim. Hyul-bu-chuke-tang (HCEt) is a well-known traditional herbal medicine that is used for the treatment of ischemic cerebrovascular disorders. We investigated the acute effects of HCEt on erythrocyte deformability and cerebrovascular CO2 reactivity (CVR) in healthy male subjects. Materials and Methods. We examined erythrocyte deformability in an HCEt group (n = 14) and a control group (n = 10). CVR was measured using hyperventilation-induced CO2 reactivity of the middle cerebral artery and transcranial Doppler (TCD) in the HCEt group (n = 11). A historical control group (n = 10) of CVR measurements was also created from our previous study. All measurements were performed prior to and 1, 2, and 3 hours after HCEt administration. Results. HCEt significantly improved erythrocyte deformability 1 hour after administration compared to the control group (2.9 ± 1.1% versus −0.6 ± 1.0%, P = 0.034). HCEt significantly improved the CVR 2 hours after administration compared to the historical control group (9.1 ± 4.0% versus −8.1 ± 4.1%, P = 0.007). The mean blood pressure and pulse rate did not vary from baseline values in either group. Conclusions. We demonstrated that HCEt improved erythrocyte deformability and CVR. Our findings suggest that an improvement in erythrocyte deformability contributes to HCEt's effect on cerebral microcirculation

    predictive factors for longer operative times for thyroidectomy

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    Background/Objective: Conventional open thyroidectomy is considered as a safe surgery nowadays. However, surgeons sometimes encounter unexpected difficulty when performing thyroidectomies. The aim of this paper was to identify the predictors of a difficult thyroidectomy for the management of patients with papillary thyroid carcinoma. Methods: A database of patients who underwent open conventional thyroidectomy with cervical lymph node dissection after diagnosed papillary thyroid carcinoma between July 2008 and June 2013 was examined. In addition, the patients were subgrouped by difficult thyroidectomy (DT) and nondifficult thyroidectomy to determine the predictors of DT according to operation time. Clinicopathologic characteristics, surgical outcomes, and postoperative morbidities were investigated. Results: No between-group differences in clinicopathologic factors and postoperative complications, except for male sex (p < 0.001) and tumor size (p = 0.039), were noted. Male sex [odds ratio (OR) 4.158, 95% confidence interval (CI) 2.020–8.559, p = 0.043] and age < 45 years (OR 2.239, 95% CI 1.304–3.843, p = 0.003) were independent factors associated with DT in a multivariate logistic regression model. Elevated antithyroglobulin antibody (OR 1.004, 95% CI 1.000–1.008, p = 0.030) was a variable which is statistically significant, but not clinically significant. Discussion: Young age and male sex might be regarded as predictors of DT. Expecting DT before surgery might help surgeons, especially beginners, prevent troublesome situations

    The Impact of Korean Medicine Treatment on the Incidence of Parkinson&apos;s Disease in Patients with Inflammatory Bowel Disease: A Nationwide Population-Based Cohort Study in South Korea

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    We aimed to investigate the association between Korean medicine (KM) treatment and the risk of Parkinson&apos;s Disease (PD) in patients with inflammatory bowel disease (IBD) in South Korea. This study analyzed data from the National Health Insurance Service-Senior cohort in South Korea. The 1816 IBD patients enrolled in the analysis comprised 411 who received only conventional treatment (monotherapy group) and 1405 who received both conventional and KM treatments (integrative therapy group). The risk of PD in patients with IBD was significantly lower in the integrative therapy group than in the monotherapy group after adjusting for confounding variables (adjusted hazard ratio (HR), 0.56; 95% confidence interval (CI) = 0.34-0.92). In the mild Charlson Comorbidity Index (CCI) group, the risk of PD in patients with IBD in the integrative therapy group was 0.39 times lower (adjusted HR, 95% CI = 0.20-0.77) than that in the monotherapy group. However, there was no significant difference in the risk of PD in patients with IBD between the integrative therapy and monotherapy groups among individuals with severe CCI (adjusted HR, 0.90; 95% CI = 0.41-1.96). IBD patients are at a decreased risk of PD when they receive integrative therapy. KM treatment may prevent PD in IBD patients.Y
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