Spectral Properties of Prompt Emission of Four Short Gamma-Ray Bursts Observed by the Suzaku-WAM and the Konus-Wind

We have performed a joint analysis of prompt emission from four bright short gamma-ray bursts (GRBs) with the Suzaku-WAM and the Konus-Wind experiments. This joint analysis allows us to investigate the spectral properties of short-duration bursts over a wider energy band with a higher accuracy. We find that these bursts have a high E$_{\rm peak}$, around 1 MeV and have a harder power-law component than that of long GRBs. However, we can not determine whether these spectra follow the cut-off power-law model or the Band model. We also investigated the spectral lag, hardness ratio, inferred isotropic radiation energy and existence of a soft emission hump, in order to classify them into short or long GRBs using several criteria, in addition to the burst duration. We find that all criteria, except for the existence of the soft hump, support the fact that our four GRB samples are correctly classified as belonging to the short class. In addition, our broad-band analysis revealed that there is no evidence of GRBs with a very large hardness ratio, as seen in the BATSE short GRB sample, and that the spectral lag of our four short GRBs is consistent with zero, even in the MeV energy band, unlike long GRBs. Although our short GRB samples are still limited, these results suggest that the spectral hardness of short GRBs might not differ significantly from that of long GRBs, and also that the spectral lag at high energies could be a strong criterion for burst classification.Comment: 23 pages, 6 figures, accepted for Publications of the Astronomical Society of Japa

Cysteine string protein 1 (CSP1) modulates insulin sensitivity by attenuating glucose transporter 4 (GLUT4) vesicle docking with the plasma membrane

Insulin stimulates glucose transporter 4 (GLUT4) vesicle recruitment from its intracellular storage site to the plasma membrane. Cysteine string protein 1 (CSP1) is a SNARE-binding protein involved in the vesicular trafficking of neurotransmitters and other exocytic processes. In this study, we investigated the involvement of CSP1 in insulin-dependent GLUT4 recruitment in 3T3-L1 adipocytes. Over-expression of wild-type CSP1 led to attenuated insulin-stimulated glucose uptake without any change in GLUT4 content in the plasma membrane, rather it inhibits docking by blocking the association of VAMP2 with syntaxin 4. In contrast, knockdown of CSP1 enhanced insulin-stimulated glucose uptake. The mRNA and protein expression of CSP1 was elevated in 3T3-L1 adipocytes in insulin resistant states caused by high levels of palmitate and chronic insulin exposure. Taken together, the results of this study suggest that CSP1 is involved in insulin resistance by interrupting GLUT4 vesicle docking with the plasma membrane

Characteristics of optical CT for gel dosimeters- distortion and its calibration and resolution -

放射線の照射量を ３ 次元的に測定することを目指し、ゲル線量計用の光学 CT 装置の開発を行っている。本研究では、性能評価の 1 つである MTF を調べた。また試料を水中で測定することも検討されているが、水中での測定では像が拡大し歪むことがわかった。このため、最初にこの影響と補正方法について検討をおこなった。その結果、水中での測定では拡大率は画像の中心で 1３0% であった。歪み率は画像中心から 5 cm の場所で 15%であった。この歪みは、OpenCV を用いて補正することが可能である。OpenCV は様々な画像処理が含まれたライブラリであり、オープンソースである。この OpenCV を用いた補正後は画像中心から 5 cm の場所では歪み率が 5 ％以下に改善された。MTF の測定にはワイヤ法（直径 0.２6mm）を用いて測定を行ったところ、水中で測定したほうが、良いMTF を得られることがわかった。これは試料が拡大されて撮影されるからである。We have developed and evaluated a prototype optical computed tomography (CT) for polymer gel dosimetry that measures the amount of irradiation in three dimensions. We investigated the modulation transfer function (MTF) to evaluate performance. The sample was placed underwater and measured. The image of the sample underwater was shown to be distorted. First, we studied the influence of this distortion and developed a calibration method. The magnification power was 1３0% at the center of the image when the sample was underwater. The image distortion was 15% at a point 5 cm from the center of the image. We corrected for this distortion using OpenCV, an open source computer vision and machine learning software library. After calibration using OpenCV, the rate of distortion improved and became ≤ 5% at the point 5 cm from the center of the image. Next, we measured MTF of the prototype optical CT using a wire 0.２6 mm in diameter. The results indicated that MTF became more visible when the sample was placed underwater, because the sample looked larger

Effect of oxidative stress on expression and function of human and rat organic anion transporting polypeptides in the liver

Reactive oxygen species (ROS) have physiological function and involve alteration of physical state. However, it is not clear effect of oxidative stress on pharmacokinetics. Organic anion transporting polypeptides (human: OATPs, rodent: Oatps) are important for uptake of endogenous and exogenous compounds into hepatocytes. Thus, alteration of OATPs/Oatps expression level may affect pharmacokinetics of various drugs. In this study, we investigated the alteration of OATPs/Oatps expression levels and function by oxidative stress, and the effect of alteration of those on pharmacokinetics of a typical OATPs/Oatps substrate pravastatin. OATPs/Oatps expression levels and function were altered by H2O2-induced oxidative stress in in vitro experiments. The alteration of Oatps expression by oxidative stress also occurred in in vivo experiments. Oatp1a1, Oatp1a4 and Oatp1b2 expression in the liver were decreased in rats fed powdery diet containing 2% inosine, which induces oxidative stress through activation of xanthine oxidase, for 1 day. The decrease in Oatps expression levels by oxidative stress caused the suppression of pravastatin uptake to the liver, and resulted in high plasma concentration of pravastatin and low biliary excretion. In conclusion, oxidative stress induces alteration of OATPs/Oatps expression and function in hepatocytes, resulting in alteration of pharmacokinetics of their substrates. (C) 2013 Elsevier B.V. All rights reserved

Intestinal P-glycoprotein Expression is Multimodally Regulated by Intestinal Ischemia-Reperfusion

Purpose. Reactive oxygen species (ROS) have multiple physiological effects that are amount-dependent. ROS are one of the causes of intestinal ischemia-reperfusion (I/R) injury. In this study, we investigated whether the amount of ROS and the degree of intestinal I/R injury affect the expression level of P-glycoprotein (P-gp). Methods. We used hydrogen peroxide (H2O2) as ROS in in vitro experiments. Intestinal I/R model rats, which were subjected 15-min ischemia (I/R-15), were used in in vivo experiments. Results. P-gp expression in Caco-2 cells was increased in response to 1 mu M of H2O2 but decreased upon exposure to 10 mM of H2O2. We previously reported that P-gp expression is decreased after intestinal I/R with 30-min ischemia (I/R-30), which time a large amount of ROS is generated. I/R-15 induced slightly less mucosal and oxidative injury than did I/R-30. P-gp expression in the jejunum was increased at 1 h after I/R-15, and ileal paracellular permeability was increased. The blood concentration of tacrolimus, a P-gp substrate, was lower during 0-20 min but was higher during 40-90 min post-administration compared with that in the sham-operated rats. P-gp expression in the ileum was decreased at 6 h after I/R-15, due to abnormal localization of P-gp, resulting in a high blood tacrolimus concentration in rats reperfused for 6 h. Conclusions. ROS multimodally regulate P-gp expression depending on its amount. This is important for understanding the pattern of P-gp expression after intestinal I/R

A full-particle Martian upper thermosphere-exosphere model using the DSMC method

International audienceA one-dimensional full-particle model of the Martian upper thermosphere-exosphere has been developed, where the Direct Simulation Monte Carlo (DSMC) method is applied to both thermal and non-thermal components. Our full-particle model can self-consistently solve the transition from collisional to collisionless domains in the upper thermosphere, so that the energy deposition from non-thermal energetic components to thermal components in the transition region is properly described. For the solar EUV condition during the Viking-1 measurement (1 EUV case), computed density profiles are in good agreement with those observed by Viking 1 and with the conventional model. For a solar EUV flux six times the Viking-1 condition (6 EUV case), the computed heating efficiency is essentially the same as 1 EUV case but slightly increases by about 10 % below the exobase, and temperature deviates from the conventional model in and above the transition region. This result suggests that the conventional heating efficiency of 0.18 is a good approximation for low (1 EUV case) to moderately strong (6 EUV case) solar EUV conditions but would be inappropriate for an extremely strong solar EUV (up to ~100 times stronger flux) environment. We also find that applying different models of the CO2-O collisional energy transfer rate results in a difference in the calculated exobase temperature by 150 K for 6 EUV case

Photochemical and RadiatiOn Transport model for Extensive USe (PROTEUS)

We introduce a new flexible one-dimensional photochemical model named Photochemical and RadiatiOn Transport model for Extensive USe (PROTEUS), which consists of a Python graphical user interface (GUI) program and Fortran 90 modules. PROTEUS is designed for adaptability to many planetary atmospheres, for flexibility to deal with thousands of or more chemical reactions with high efficiency, and for intuitive operation with GUI. Chemical reactions can be easily implemented into the Python GUI program in a simple string format, and users can intuitively select a planet and chemical reactions on GUI. Chemical reactions selected on GUI are automatically analyzed by string parsing functions in the Python GUI program, then applied to the Fortran 90 modules to simulate with the selected chemical reactions on a selected planet. PROTEUS can significantly save the time for those who need to develop a new photochemical model; users just need to write chemical reactions in the Python GUI program and just select them on GUI to run a new photochemical model