160 research outputs found

    Design and Robustness Evaluation of Valley Topological Elastic Wave Propagation in a Thin Plate with Phononic Structure

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    Based on the concept of band topology in phonon dispersion, we designed a topological phononic crystal in a thin plate for developing an efficient elastic waveguide. Despite that various topological phononic structures have been actively proposed, a quantitative design strategy of the phononic band and its robustness assessment in an elastic regime are still missing, hampering the realization of topological acoustic devices. We adopted a snowflake-like structure for the crystal unit cell and determined the optimal structure that exhibited the topological phase transition of the planar phononic crystal by changing the unit cell structure. The bandgap width could be adjusted by varying the length of the snow-side branch, and a topological phase transition occurred in the unit cell structure with threefold rotational symmetry. Elastic waveguides based on edge modes appearing at interfaces between crystals with different band topologies were designed, and their transmission efficiencies were evaluated numerically and experimentally. The results demonstrate the robustness of the elastic wave propagation in thin plates. Moreover, we experimentally estimated the backscattering length, which measures the robustness of the topologically protected propagating states against structural inhomogeneities. The results quantitatively indicated that degradation of the immunization against the backscattering occurs predominantly at the corners in the waveguides, indicating that the edge mode observed is a relatively weak topological state

    Inhibitory Effects of Prior Low-dose X-irradiation on Cold-induced Brain Injury in Mouse

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    We examined the inhibitory effects of low-dose X-irradiation on mouse brain tissue with cold-induced injury by comparing tissue samples from three groups of mice: control, sham-irradiated cold-exposed, and X-ray-irradiated (0.5 Gy) cold-exposed mice. The water content in brain increased significantly in the sham-irradiated group following the cold-induced injury relative to the control group. However, water content in brain tissue from the X-ray-irradiated group was significantly lower than that from the sham-irradiated group. Levels of antioxidants, such as superoxide dismutase and glutathione, in brain tissue from the X-ray-irradiated group were higher than those from the sham-irradiated group. Moreover, the cold injury-induced cell death, particularly apoptosis, while low-dose irradiation inhibited cell death, especially among glial cells, but not numeral cells. These findings suggest that prior low-dose X-irradiation activated antioxidant function and inhibited cold-induced brain injury

    Temporal and Spectral Variabilities of High Energy Emission from Blazars Using Synchrotron Self-Compton Models

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    Multiwavelength observations of blazars such as Mrk 421 and Mrk 501 show that they exhibit strong short time variabilities in flare-like phenomena. Based on the homogeneous synchrotron self-Compton (SSC) model and assuming that time variability of the emission is initiated by changes in the injection of nonthermal electrons, we perform detailed temporal and spectral studies of a purely cooling plasma system. One important parameter is the total injected energy E and we show how the synchrotron and Compton components respond as E varies. We discuss in detail how one could infer important physical parameters using the observed spectra. In particular, we could infer the size of the emission region by looking for exponential decay in the light curves. We could also test the basic assumption of SSC by measuring the difference in the rate of peak energy changes of synchrotron and SSC peaks. We also show that the trajectory in the photon-index and flux plane evolves clockwise or counter-clockwise depending on the value of E and observed energy bands.Comment: 35 pages, 18 figures, accepted by the Astrophysical Journa

    Reactivity of CA19-9 and CA125 in Histological Subtypes of Epithelial Ovarian Tumors and Ovarian Endometriosis

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    Previous reports have shown that some ovarian endometrioid adenocarcinomas and ovarian clear cell adenocarcinomas derive from ovarian endometriosis (OE), and that endocervical-like mucinous borderline ovarian tumors are associated with OE. We examined the relationship between the staging and histological subtypes of OE or epithelial ovarian tumors (EOT) and the serum levels of carbohydrate antigen 19-9 (CA19-9) and carbohydrate antigen 125 (CA125) to evaluate the potential of these markers for preoperative diagnosis. First, we analyzed the preoperative serum levels of CA19-9 and CA125 in 195 patients who were histopathologically diagnosed with OE or EOT. We then performed a case-control study in which 308 women were enrolled, the 195 women described above and 113 healthy women as control subjects. Serum CA19-9 and CA125 levels were found to be useful in differentiating between OE and serous adenocarcinoma, but not between OE and other EOT. Moreover, serum CA19-9 levels were useful for preoperative assessment between OE and stage I mucinous borderline ovarian tumors, with or without the interstitial infiltration. In addition, considering that the serum CA19-9 levels in stage I mucinous borderline ovarian tumors were elevated via the interstitial infiltration of leukocytes and that precancerous lesions are associated with a cancerous glycosylation disorder in the process of inflammatory carcinogenesis, the CA19-9 level may be considered a suitable biomarker for estimating drug susceptibility

    Efficacy and Safety of Three-dimensional Conformal Radiotherapy for Macroscopic Vascular Invasion of Hepatocellular Carcinoma

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    Chemotherapy is insufficient to treat macroscopic vascular invasion (MVI) of hepatocellular carcinoma (HCC). We retrospectively investigated the treatment outcomes of patients who underwent three-dimensional conformal radiotherapy (3D-CRT) for HCC MVI and analyzed prognostic factors by multivariate analysis using a Cox proportional hazard model. Sixty-five patients were studied. MVI sites were the portal vein (n=48 patients), portal and hepatic veins (n=8), and hepatic vein (n=9). The median irradiation dose was 50 Gy. The median survival time (MST) was 7.5 months. Performance status 2 or 3, modified albumin-bilirubin grade 2b or 3, and massive/diffuse type were poor prognostic factors. Nineteen patients (29%) with a treatment effect of 3 or 4 (≥ 50% of tumor necrosis or regression) at the irradiation sites according to the Response Evaluation Criteria in Cancer of the Liver showed longer survival than those with an effect of 1 or 2 (MST 18.7 vs. 5.9 months, p<0.001). No treatment-related death occurred. The hepatic function reserve was preserved in more than 70% of patients. 3D-CRT controlled HCC MVI safely and was suggested to be a good treatment option

    Low-dose X-irradiation inhibits brain injury 1 Regular Paper Inhibitory effects of prior low-dose X-irradiation on cold-induced brain injury in mouse

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    Running title: Low-dose X-irradiation inhibits brain injury ABBREVIATIONS: BBB, blood-brain barrier; ROS, reactive oxygen species; SOD, superoxide dismtase; GPx, glutathione peroxidase; GR, glutathione reductase; total GSH, total glutathione; EDTA, ethylendiaminetetraacetic acid; NBT, nitroblue tetrazolium; H 2 O 2 , hydrogen peroxide; MDA, malondialdehyde; HE, hematoxylin-eosin; KB, Kluver-Barrera; TUNEL, Terminal dUTP in situ nick-end labeling; PBS, phosphate-buffered saline; DAB, 3,39-diaminobenzidine; SEM, standard error of the mean; MCA, middle cerebral artery Low-dose X-irradiation inhibits brain injury 2 Abstract We examined the inhibitory effects of low-dose X-irradiation on mouse brain tissue with cold-induced injury by comparing tissue samples from three groups of mice: control, sham-irradiated cold-exposed, and X-ray-irradiated (0.5 Gy) cold-exposed mice. The water content in brain increased significantly in the sham-irradiated group following the cold-induced injury relative to the control group. However, water content in brain tissue from the X-ray-irradiated group was significantly lower than that from the sham-irradiated group. Levels of antioxidants, such as superoxide dismutase and glutathione, in brain tissue from the X-ray-irradiated group were higher than those from the sham-irradiated group. Moreover, the cold injury induced cell death, particularly apoptosis, while low-dose irradiation inhibited cell death, especially among glial cells, but not numeral cells. These findings suggest that prior low-dose X-irradiation activated antioxidant function and inhibited cold-induced brain injury

    Usefulness of helical computed tomography in diagnosing pulmonary vein stenosis in infants.

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    We investigated the usefulness of helical computed tomography(CT)in the morphological diagnosis of pulmonary vein stenosis, particularly that in infants and small children. In total, 20 helical CT examinations were performed in 10 post-operative cases of Total Anomalous Pulmonary Venous Drainage(TAPVD), 3 cases of single right ventricle, and 1 case of single left ventricle. In all cases, distinct morphological imaging was possible. Pulmonary vein stenosis could be categorized into three types: (1)stenosis from the anastomosis of the common pulmonary vein (CPV)-the left atrium (LA) to the peripheral pulmonary vein; (2) stenosis only at the anastomosis of CPV-LA; and (3) stenosis due to compression by nearby organs. Coronal views by multiplanar reconstruction (MPR) provided morphological information along the up-down direction of the body axis. Morphological diagnosis of pulmonary vein stenosis is important in deciding prognosis and therapeutic regimens, and helical CT was considered useful for such diagnosis in our 14 young patients.</p

    No Different Sensitivity in Terms of Whole-Body Irradiation between Normal and Acatalasemic Mice

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    To elucidate the radiosensitivity of an acatalasemic mouse, we examined the time and dose-dependency in the survival rates, the lymphocytes and the intestinal epithelial cells, and the antioxidant function after 3.0 to 12.0 Gy whole body irradiation. Results showed that no significant differences between acatalasemic mice and normal mice were observed in the survival rates and the histological changes in spleens and small intestine after each irradiation. The catalase activities in livers and spleens of acatalasemic mice were significantly lower than those of normal mice and the glutathione peroxidase activity in livers of acatalasemic mice was significantly higher than that of normal mice. At 10 days after 6.0 Gy irradiation, the catalase activities in livers of acatalasemic and normal mice and that in spleens of normal mice significantly decreased compared with no-irradiation control, and there were no differences between those catalase activities. The total glutathione content in acatalasemic mice was significantly higher than that in normal mice at 10 days after 6.0 Gy irradiation. These findings suggested that the radiosensitivity of acatalasemic mice in terms of whole body irradiation doesn’t significantly differ from that of normal mice, probably due to compensated sufficient contents of glutathione peroxidase and total glutathione in acatalasemic mice
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