Tau functions as Widom constants

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

Delayed Presentation of Renocolic Fistula at 4 Months after Blunt Abdominal Trauma

Causes of previously reported reno-colic fistulas included primary renal and colonic pathologic states involving infectious, malignant or other inflammatory processes. However, reno-colic fistula after renal injury is extremely uncommon. We report an unusual delayed presentation of reno-colic fistula that occurred at 4 months later after blunt abdominal trauma

Development and characterization of polymeric hollow fiber membrane with high CO2 separation performance

In this study, we prepared the polyimide based hollow fiber membrane with High CO2 permeance property. In other to prepare high permeable gas separation membrane, we synthesized novel polyimide material using 6FDA, Durene and PEG monomers. And then general property of the polyimide membrane is characterized using flat sheet type of membrane. The membranes were prepared under various controlled conditions such as retention time and concentration of the polymer. And then the hollow fiber membrane is also prepared and then characterized for confirmation of their potential. The Ionic liquid mainchain polymer is also developed to investigate the gas permeability and potential for utilization to coating materials of hollow fiber membrane. Polyimide with pendant ionic liquid (Im-PpC) membrane showed the high α(CO2/N2) value and the main chain polymer prepared by UV crosslinking with PEG & ILMP crosslinker also showed high α(CO2/N2). Please click Additional Files below to see the full abstract

Interferometric Monitoring of Gamma-ray Bright AGNs: 4C +28.07 and its Synchrotron Self-absorption Spectrum

We present the analysis results of the simultaneous multifrequency observations of the blazar 4C +28.07. The observations were conducted by the Interferometric Monitoring of Gamma-ray Bright Active Galactic Nuclei (iMOGABA) program, which is a key science program of the Korean Very Long Baseline Interferometry (VLBI) Network (KVN). Observations of the iMOGABA program for 4C +28.07 were conducted from 16 January 2013 (MJD 56308) to 13 March 2020 (MJD 58921). We also used {\gamma}-ray data from the Fermi Large Array Telescope (Fermi-LAT) Light Curve Repository. We divided the iMOGABA data and the Fermi-LAT data into five periods from 0 to 4, according to the prosody of the 22 GHz data and the presence or absence of the data. In order to investigate the characteristics of each period, the light curves were plotted and compared. However, a peak was observed earlier than the period of a strong {\gamma}-ray flare at 43-86 GHz in period 3 (MJD 57400-58100). Therefore, we assumed that the minimum total CLEANed flux density for each frequency was quiescent flux (Sq), with the variable flux (Svar) obtained by subtracting Sq from the values of the total CLEANed flux density. We then compared the variability of the spectral indices ({\alpha}) between adjacent frequencies. Most notably, {\alpha}22-43 showed optically thick spectra in the absence of a strong {\gamma}-ray flare, and when the flare appeared, {\alpha}22-43 became optically thinner. In order to find out the characteristics of the magnetic field in the variable region, the magnetic field strength in the synchrotron self-absorption (BSSA) and the equipartition magnetic field strength (Beq) were obtained. We found that BSSA is largely consistent with Beq within the uncertainty, implying that the SSA region in the source is not significantly deviated from the equipartition condition in the {\gamma}-ray quiescent periods.Comment: 23 pages, accepted by JKA

Aspirin Has Antitumor Effects via Expression of Calpain Gene in Cervical Cancer Cells

Aspirin and other nonsteroidal anti-inflammatory drugs show efficacy in the prevention of cancers. It is known that they can inhibit cyclooxygenases, and some studies have shown that they can induce apoptosis. Our objective in this study was to investigate the mechanism by which aspirin exerts its apoptosis effects in human cervical cancer HeLa cells. The effect of aspirin on the gene expression was studied by differential mRNA display RT-PCR. Among the isolated genes, mu-type calpain gene was upregulated by aspirin treatment. To examine whether calpain mediates the antitumor effects, HeLa cells were stably transfected with the mammalian expression vector pCR3.1 containing mu-type calpain cDNA (pCRCAL/HeLa), and tumor formations were measured in nude mice. When tumor burden was measured by day 49, HeLa cells and pCR/HeLa cells (vector control) produced tumors of 2126 mm3 and 1638 mm3, respectively, while pCRCAL/HeLa cells produced markedly smaller tumor of 434 mm3 in volume. The caspase-3 activity was markedly elevated in pCRCAL/HeLa cells. The increased activity levels of caspase-3 in pCRCAL/HeLa cells, in parallel with the decreased tumor formation, suggest a correlation between caspase-3 activity and calpain protein. Therefore, we conclude that aspirin-induced calpain mediates an antitumor effect via caspase-3 in cervical cancer cells

Synthesis and characterization of PEEK containing imidazole moiety and effect of functional groups

Anion exchange membrane fuel cells (AEMFCs) are considered as one of the alternative power generation systems due to their high efficiency. Anion exchange membrane (AEM) is a key component in fuel cells for the transfer of anion which is effect to the performance of the fuel cell system. \Therefore, it needs to have high chemical, mechanical, and thermal stabilities, as well as excellent electrochemical properties. For these reasons, various types of novel polymeric materials have been developed for the anion exchange membrane fuel cells. Especially, hydrocarbon based polymer materials such as poly(arylene ether sulfone), poly(ether ether ketone)(PEEK), polybenzimidazole (PBI) have been fabricated for use as electrolytes in fuel cell systems. Also, a number of preparation methods have been developed to enhance the performance of fuel cell membranes. In this study, we modified the monomer by chemical modification reaction and we synthesized the PEEK based polymer with different amination degree. Also we compared the chemical stability of the PEEK based membrane with different functional groups such as ammonium and imidazolium. Finally, the effect of the contents of the anion exchange groups in the PEEK based polymer was evaluated in terms of morphology, water behavior, mechanical properties, chemical stability and ion conductivity. Please click Additional Files below to see the full abstract

Xenon excimer emission from multicapillary discharges in direct current mode

Microdischarges in xenon have been generated in a pressure range of 400–1013 mbar with a fixed flow rate of 100 sccm. These microdischarges are obtained from three metallic capillary tubes in series for excimer emission. Total discharge voltage is thrice as large as that of a single capillary discharge tube at current levels of up to 12 mA. Total spectral irradiance of vacuum ultraviolet (VUV) emission also increases significantly compared to that of the single capillary discharge. Further, the irradiance of the VUV emission is strongly dependent on pressure as well as the discharge current