654 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

    Retrograde Tempofilter II™ Placement within the Superior Vena Cava in a Patient with Acute Upper Extremity Deep Venous Thrombosis: the Filter Stands on Its Head

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    The Tempofilter II is a widely used temporary vena cava filter. Its unique design, which includes a long tethering catheter with a subcutaneous anchor, facilitates the deployment and retrieval of the device. Despite this, the Tempofilter II has been used only in the inferior vena cava of patients with lower extremity deep venous thrombosis. In this article, we present a case of superior vena cava filtering using the Tempofilter II in patients with upper extremity deep venous thrombosis

    Physical properties and biological effects of mineral trioxide aggregate mixed with methylcellulose and calcium chloride

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    Objectives: Methylcellulose (MC) is a chemical compound derived from cellulose. MTA mixed with MC reduces setting time and increases plasticity. This study assessed the influence of MC as an anti-washout ingredient and CaCl2 as a setting time accelerator on the physical and biological properties of MTA. Material and Methods: Test materials were divided into 3 groups; Group 1(control): distilled water; Group 2: 1% MC/CaCl2; Group 3: 2% MC/CaCl2. Compressive strength, pH, flowability and cell viability were tested. The gene expression of bone sialoprotein (BSP) was detected by RT-PCR and real­ time PCR. The expression of alkaline phosphatase (ALP) and mineralization behavior were evaluated using an ALP staining and an alizarin red staining. Results: Compressive strength, pH, and cell viability of MTA mixed with MC/CaCl2 were not significantly different compared to the control group. The flowability of MTA with MC/CaCI2 has decreased significantly when compared to the control (

    Effect of a multi-layer infection control barrier on the micro-hardness of a composite resin

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    OBJECTIVE: The aim of this study was to evaluate the effect of multiple layers of an infection control barrier on the micro-hardness of a composite resin. MATERIAL AND METHODS: One, two, four, and eight layers of an infection control barrier were used to cover the light guides of a high-power light emitting diode (LeD) light curing unit (LCU) and a low-power halogen LCU. The composite specimens were photopolymerized with the LCUs and the barriers, and the micro-hardness of the upper and lower surfaces was measured (n=10). The hardness ratio was calculated by dividing the bottom surface hardness of the experimental groups by the irradiated surface hardness of the control groups. The data was analyzed by two-way ANOVA and Tukey's HSD test. RESULTS: The micro-hardness of the composite specimens photopolymerized with the LED LCU decreased significantly in the four- and eight-layer groups of the upper surface and in the two-, four-, and eight-layer groups of the lower surface. The hardness ratio of the composite specimens wa

    Ginseng total saponin attenuates myocardial injury via anti-oxidative and anti-inflammatory properties

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    AbstractBackgroundGinseng total saponin (GTS) contains various ginsenosides. These ginsenosides are widely used for treating cardiovascular diseases in Asian communities. The aim of this study was to study the effects of GTS on cardiac injury after global ischemia and reperfusion (I/R) in isolated guinea pig hearts.MethodsAnimals were subjected to normothermic ischemia for 60 minutes, followed by 120 minutes of reperfusion. GTS significantly increased aortic flow, coronary flow, and cardiac output. Moreover, GTS significantly increased left ventricular systolic pressure and the maximal rate of contraction (+dP/dtmax) and relaxation (−dP/dtmax). In addition, GTS has been shown to ameliorate electrocardiographic changes such as the QRS complex, QT interval, and RR interval.ResultsGTS significantly suppressed the biochemical parameters (i.e., lactate dehydrogenase, creatine kinase-MB fraction, and cardiac troponin I levels) and normalized the oxidative stress markers (i.e., malondialdehyde, glutathione, and nitrite). In addition, GTS also markedly inhibits the expression of interleukin-1β (IL-1β), IL-6, and nuclear factor-κB, and improves the expression of IL-10 in cardiac tissue.ConclusionThese data indicate that GTS mitigates myocardial damage by modulating the biochemical and oxidative stress related to cardiac I/R injury

    Impact of gate direct tunneling current on circuit performance: a simulation study

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    Height Restoration after Balloon Kyphoplasty in Rheumatoid Patients with Osteoporotic Vertebral Compression Fracture

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    Study DesignRetrospective study.PurposeThis study was conducted to compare vertebral body height restoration rate in rheumatoid arthritis (RA) patients who had undergone percutaneous balloon kyphoplasty (KP) with that of control group who had matched age, sex, body mass index, and bone mineral density.Overview of LiteratureThere is no report on result of KP in RA patients.MethodsPostoperative height restoration rate of RA group consisting of 15 patients (18 vertebral bodies) who had undergone KP due to osteoporotic vertebral compression fracture with a 30% or higher vertebral compression rate between May 2005 and January 2013 were compared to control group consisting of 38 patients (39 vertebral bodies) who had matched age, sex, body mass index, and bone mineral density.ResultsNo statically significant difference in age (p=0.846), sex (p=0.366), body mass index (p=0.826), bone mineral density (p=0.349), time to surgery (p=0.528), polymethylmethacrylate injection time (p=0.298), or amount (p=0.830) was found between the RA group and the control group. However, preoperative compression rate in the RA group was significantly (p=0.025) higher compared to that in the control group. In addition, postoperative height restoration rate showed significant correlation with the RA group (p=0.008). Although higher incidence of recollapse occurred in the RA group compared to that in the control group, the difference was not statistically significant (p=0.305).ConclusionsCompared to the control group, RA patients showed higher compression rate and higher vertebral restoration rate after KP, indirectly indicating weaker bone quality in patients with RA. Higher incidence of recollapse occurred in the RA group compared to that in the control group, although it was not statistically significant

    Comparison of Measurement and Prediction of ITU-R Recommendation P.1546

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    This paper compares measurement with prediction of ITU-R Recommendation P.1546. This recommendation mainly depends on propagation curves which are based on the measurement result. The basic field strength is derived from the curve corresponding to transmitting antenna height, frequency and required distance and then correction factor is added to this. There are two important correction values in this recommendation. First factor is the correction for receiving/mobile antenna height and second factor is the terrain clearance angle (TCA) correction. This paper specially focuses on first correction factor with regard to R which is representative of the height of the ground cover surrounding receiving/mobile antenna. We propose several considerations to enhance the prediction accuracy of ITU-R Recommendation P.1546

    Performance of Channel Prediction Using 3D Ray-tracing Scheme Compared to Conventional 2D Scheme

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    Channel prediction tools using ray-tracing scheme can be used to get information of communication channel instead of channel measurement. Three dimensional (3D) ray-tracing technique is known for the better accuracy compared to two dimensional (2D) ray-tracing. But it requires a lot of calculations, thus 2D simulation has been generally performed. This paper shows how precious 3D ray-tracing predicts the received power indoors compared to 2D one. For this work, wave propagation phenomena are analyzed using Finite Difference Time Domain (FDTD) method and the channel measurement data also will be offered as a standard of comparison
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