60 research outputs found

    Neutron Energy Spectrum Measurements with a Compact Liquid Scintillation Detector on EAST

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    A neutron detector based on EJ301 liquid scintillator has been employed at EAST to measure the neutron energy spectrum for D-D fusion plasma. The detector was carefully characterized in different quasi-monoenergetic neutron fields generated by a 4.5 MV Van de Graaff accelerator. In recent experimental campaigns, due to the low neutron yield at EAST, a new shielding device was designed and located as close as possible to the tokamak to enhance the count rate of the spectrometer. The fluence of neutrons and gamma-rays was measured with the liquid neutron spectrometer and was consistent with 3He proportional counter and NaI (Tl) gamma-ray spectrometer measurements. Plasma ion temperature values were deduced from the neutron spectrum in discharges with lower hybrid wave injection and ion cyclotron resonance heating. Scattered neutron spectra were simulated by the Monte Carlo transport Code, and they were well verified by the pulse height measurements at low energies.Comment: 19 pages,10 figures, 1 tabl

    Estimating continental river basin discharges using multiple remote sensing data sets

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    AbstractRivers act as a source of fresh water for terrestrial life, yet the discharges are poorly documented since the existing direct observations are inadequate and some observation stations have been interrupted or discontinued. Discharge estimates using remote sensing thus have a great potential to supplement ground observations. There are remote sensing methods established to estimate discharge based on single parameter derived relationships; however, they are limited to specific sections due to their empirical nature. In this study, we propose an innovative method to estimate daily discharges for continental rivers (with river channel widths >800m (Birkett and Beckley, 2010)) using two satellite derived parameters. Multiple satellite altimetry data and Moderate Resolution Imaging Spectroradiometer (MODIS) data are used to provide a time series of river stages and effective river width. The derived MODIS and altimetry data are then used to optimize unknown parameters in a modified Manning's equation. In situ measurements are used to derive rating curves and to provide assessments of the estimated results. The Nash–Sutcliffe efficiency values for the estimates are between 0.60 and 0.97, indicating the power of the method and accuracy of the estimations. A comparison with a previously developed empirical multivariate equation for estimating river discharge shows that our method produces superior results, especially for large rivers. Furthermore, we found that discharge estimates using both effective river width and stage information consistently outperform those that only use stage data

    BRG1 and BRM SWI/SNF ATPases redundantly maintain cardiomyocyte homeostasis by regulating cardiomyocyte mitophagy and mitochondrial dynamics in vivo

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    There has been an increasing recognition that mitochondrial perturbations play a central role in human heart failure. Discovery of mitochondrial networks, whose function is to maintain the regulation of mitochondrial biogenesis, autophagy (‘mitophagy’) and mitochondrial fusion/fission, are new potential therapeutic targets. Yet our understanding of how the molecular underpinning of these processes is just emerging. We recently identified a role of the SWI/SNF ATP-dependent chromatin remodeling complexes in the metabolic homeostasis of the adult cardiomyocyte using cardiomyocyte-specific and inducible deletion of the SWI/SNF ATPases BRG1 and BRM in adult mice (Brg1/Brm double mutant mice). To build upon these observations in early alterated metabolism, the present study looks at the subsequent alterations in mitochondrial quality control mechanisms in the impaired adult cardiomyocyte. We identified that Brg1/Brm double-mutant mice exhibited an increased mitochondrial biogenesis, increases in ‘mitophagy’, and alterations in mitochondrial fission and fusion that led to small, fragmented mitochondria. Mechanistically, increases in the autophagy and mitophagy-regulated proteins Beclin1 and Bnip3 were identified, paralleling changes seen in human heart failure. Cardiac mitochondrial dynamics were perturbed including decreased mitochondria size, reduced number, and altered expression of genes regulating fusion (Mfn1, Opa1) and fission (Drp1). We also identified cardiac protein amyloid accumulation (aggregated fibrils) during disease progression along with an increase in pre-amyloid oligomers and an upregulated unfolded protein response including increased GRP78, CHOP, and IRE-1 signaling. Together, these findings described a role for BRG1 and BRM in mitochondrial quality control, by regulating mitochondrial number, mitophagy, and mitochondrial dynamics not previously recognized in the adult cardiomyocyte. As epigenetic mechanisms are critical to the pathogenesis of heart failure, these novel pathways identified indicate that SWI/SNF chromatin remodeling functions are closely linked to mitochondrial quality control mechanisms

    Human Papillomavirus Type 18 E6 and E7 Genes Integrate into Human Hepatoma Derived Cell Line Hep G2

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    Background and Objectives: Human papillomaviruses have been linked causally to some human cancers such as cervical carcinoma, but there is very little research addressing the effect of HPV infection on human liver cells. We chose the human hepatoma derived cell line Hep G2 to investigate whether HPV gene integration took place in liver cells as well. Methods: We applied PCR to detect the possible integration of HPV genes in Hep G2 cells. We also investigated the expression of the integrated E6 and E7 genes by using RT-PCR and Western blotting. Then, we silenced E6 and E7 expression and checked the cell proliferation and apoptosis in Hep G2 cells. Furthermore, we analyzed the potential genes involved in cell cycle and apoptosis regulatory pathways. Finally, we used in situ hybridization to detect HPV 16/18 in hepatocellular carcinoma samples. Results: Hep G2 cell line contains integrated HPV 18 DNA, leading to the expression of the E6 and E7 oncogenic proteins. Knockdown of the E7 and E6 genes expression reduced cell proliferation, caused the cell cycle arrest at the S phase, and increased apoptosis. The human cell cycle and apoptosis real-time PCR arrays analysis demonstrated E6 and E7-mediated regulation of some genes such as Cyclin H, UBA1, E2F4, p53, p107, FASLG, NOL3 and CASP14. HPV16/18 was found in only 9% (9/100) of patients with hepatocellular carcinoma. Conclusion: Our investigations showed that HPV 18 E6 and E7 genes can be integrated into the Hep G2, and we observed a low prevalence of HPV 16/18 in hepatocellular carcinoma samples. However, the precise risk of HPV as causative agent of hepatocellular carcinoma needs further study

    Surgical removal of submacular perfluorocarbon liquid with a 38-gauge flexible cannula combined with internal limiting membrane peeling and intravitreal air tamponade: a case series

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    Abstract Background To report a case series in which a modified technique was used to remove retained submacular perfluorocarbon liquid (PFCL) secondary to vitreoretinal surgery for rhegmatogenous retinal detachment. Case presentation Four patients who had undergone pars plana vitrectomy for rhegmatogenous retinal detachment were further treated with surgical intervention because of retained submacular PFCL. With a three-port pars plana approach, after the internal limiting membrane peeling with indocyanine green staining, a 38-gauge flexible cannula was used to aspirate the submacular perfluorocarbon bubble, followed by fluid-air exchange and air injection into vitreous cavity. Submacular perfluorocarbon liquid was removed successfully and visual acuity had an improvement in all cases. Conclusion The surgical removal of retained submacular PFCL using a 38-gauge flexible cannula combined with internal limiting membrane peeling and intravitreal air tamponade may provide anatomical and visual satisfactory outcomes