569 research outputs found

    Room temperature near-ultraviolet emission from In-rich InGaN/GaN multiple quantum wells

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    We grew In-rich InGaNGaN multiple quantum wells (MQWs) using growth interruption (GI) by metalorganic chemical vapor deposition. The quality of overgrown InGaNGaN QW layers in MQWs was largely affected by the crystalline quality and interfacial abruptness of the underlying QW layer. Introduction of 10 s GI was very effective in improving the crystalline quality and interfacial abruptness of InGaN QW layers, and we grew a ten periods of 1-nm -thick In-rich InGaNGaN MQW with 10 s GI and obtained a strong near-ultraviolet (UV) emission (~390 nm) at room temperature. We believe that use of less than 1-nm -thick In-rich InGaN MQW can be a candidate for near-UV source, which might replace the conventional low-indium content (<10%), thicker InGaN QW layer.open313

    Effect of growth interruption on optical properties of In-rich InGaN/GaN single quantum well structures

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    In-rich InGaN/GaN single quantum well (SQW) structures with and without growth interruption (GI) were successfully grown on sapphire substrates by metal-organic chemical vapor deposition. The optical properties were systematically investigated by photoluminescence (PL), selectively excited PL, PL excitation (PLE), and cathodoluminescence (CL) techniques. The integrated PL intensity of the main In-rich InGaN emissions for the sample grown without GI decreased only by a factor of 15.5 when the temperature increased from 11 to 300 K, while that of the sample with GI decreased by about 1040, showing very good quantum efficiency for the sample without GI. The In-rich InGaN SQW emissions have been verified by selectively excited PL spectra and by the different PLE absorption edges. CL observations showed that the epilayer of the sample without GI agglomerated together to form clusters due to the large lattice and thermal mismatches with GaN, which confine the carriers in the clusters and ensure the relatively high quantum efficiency of the sample. The sample with GI showed relatively smooth surface with cluster structures jointed together, which gives two-dimensional QW environment in its energy band structure, and its optical emission is more sensitive to temperatures than that of the sample grown without GI.open7

    Distributed functions of detection and discrimination of vibrotactile stimuli in the hierarchical human somatosensory system

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    According to the hierarchical view of human somatosensory network, somatic sensory information is relayed from the thalamus to primary somatosensory cortex (Si), and then distributed to adjacent cortical regions to perform further perceptual and cognitive functions. Although a number of neuroirnaging studies have examined neuronal activity correlated with tactile stimuli, comparatively less attention has been devoted toward understanding how vibrotactile stimulus information is processed in the hierarchical somatosensory cortical network. To explore the hierarchical perspective of tactile information processing, we studied two cases: (a) discrimination between the locations of finger stimulation; and (b) detection of stimulation against no stimulation on individual fingers, using both standard general linear model (GLM) and searchlight multi-voxel pattern analysis (MVPA) techniques. These two cases were studied on the same data set resulting from a passive vibrotactile stimulation experiment. Our results showed that vibrotactile stimulus locations on fingers could be discriminated from measurements of human functional magnetic resonance imaging (fMRI). In particular, it was in case (a) we observed activity in contralateral posterior parietal cortex (PPC) and supramarginal gyrus (SMG) but not in Si, while in case; (b) we found significant cortical activations in Si but not in PPC and SMG. These discrepant observations suggest the functional specialization with regard to vibrotactile stimulus locations, especially, the hierarchical information processing in the human somatosensory cortical areas. Our findings moreover support the general understanding that Si is the main sensory receptive area for the sense of touch, and adjacent cortical regions (i.e., PPC and SMG) are in charge of a higher level of processing and may thus contribute most for the successful classification between stimulated finger locations.open0

    Data Assimilation of AOD and Estimation of Surface Particulate Matters over the Arctic

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    In this study, more accurate information on the levels of aerosol optical depth (AOD) was calculated from the assimilation of the modeled AOD based on the optimal interpolation method. Additionally, more realistic levels of surface particulate matters over the Arctic were estimated using the assimilated AOD based on the linear relationship between the particulate matters and AODs. In comparison to the MODIS observation, the assimilated AOD was much improved compared with the modeled AOD (e.g., increase in correlation coefficients from −0.15–0.26 to 0.17–0.76 over the Arctic). The newly inferred monthly averages of PM10 and PM2.5 for April–September 2008 were 2.18–3.70 μg m−3 and 0.85–1.68 μg m−3 over the Arctic, respectively. These corresponded to an increase of 140–180%, compared with the modeled PMs. In comparison to in-situ observation, the inferred PMs showed better performances than those from the simulations, particularly at Hyytiala station. Therefore, combining the model simulation and data assimilation provided more accurate concentrations of AOD, PM10, and PM2.5 than those only calculated from the model simulations

    Data Assimilation of AOD and Estimation of Surface Particulate Matters over the Arctic

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    In this study, more accurate information on the levels of aerosol optical depth (AOD) was calculated from the assimilation of the modeled AOD based on the optimal interpolation method. Additionally, more realistic levels of surface particulate matters over the Arctic were estimated using the assimilated AOD based on the linear relationship between the particulate matters and AODs. In comparison to the MODIS observation, the assimilated AOD was much improved compared with the modeled AOD (e.g., increase in correlation coefficients from −0.15–0.26 to 0.17–0.76 over the Arctic). The newly inferred monthly averages of PM10 and PM2.5 for April–September 2008 were 2.18–3.70 μg m−3 and 0.85–1.68 μg m−3 over the Arctic, respectively. These corresponded to an increase of 140–180%, compared with the modeled PMs. In comparison to in-situ observation, the inferred PMs showed better performances than those from the simulations, particularly at Hyytiala station. Therefore, combining the model simulation and data assimilation provided more accurate concentrations of AOD, PM10, and PM2.5 than those only calculated from the model simulations

    Prognostic role of computed tomography-based, artificial intelligence-driven waist skeletal muscle volume in uterine endometrial carcinoma

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    Abstract Objectives To investigate the impact of computed tomography (CT)-based, artificial intelligence-driven waist skeletal muscle volume on survival outcomes in patients with endometrial cancer. Methods We retrospectively identified endometrial cancer patients who received primary surgical treatment between 2014 and 2018 and whose pre-treatment CT scans were available (n = 385). Using an artificial intelligence-based tool, the skeletal muscle area (cm2) at the third lumbar vertebra (L3) and the skeletal muscle volume (cm3) at the waist level were measured. These values were converted to the L3 skeletal muscle index (SMI) and volumetric SMI by normalisation with body height. The relationships between L3, volumetric SMIs, and survival outcomes were evaluated. Results Setting 39.0 cm2/m2 of L3 SMI as cut-off value for sarcopenia, sarcopenia (< 39.0 cm2/m2, n = 177) and non-sarcopenia (≥ 39.0 cm2/m2, n = 208) groups showed similar progression-free survival (PFS; p = 0.335) and overall survival (OS; p = 0.241). Using the median value, the low-volumetric SMI group (< 206.0 cm3/m3, n = 192) showed significantly worse PFS (3-year survival rate, 77.3% vs. 88.8%; p = 0.004) and OS (3-year survival rate, 92.8% vs. 99.4%; p = 0.003) than the high-volumetric SMI group (≥ 206.0 cm3/m3, n = 193). In multivariate analyses adjusted for baseline body mass index and other factors, low-volumetric SMI was identified as an independent poor prognostic factor for PFS (adjusted HR, 1.762; 95% CI, 1.051–2.953; p = 0.032) and OS (adjusted HR, 5.964; 95% CI, 1.296–27.448; p = 0.022). Conclusions Waist skeletal muscle volume might be a novel prognostic biomarker in patients with endometrial cancer. Assessing body composition before treatment can provide important prognostic information for such patients

    Improved ground-state modulation characteristics in 1.3 μm InAs/GaAs quantum dot lasers by rapid thermal annealing

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    We investigated the ground-state (GS) modulation characteristics of 1.3 μm InAs/GaAs quantum dot (QD) lasers that consist of either as-grown or annealed QDs. The choice of annealing conditions was determined from our recently reported results. With reference to the as-grown QD lasers, one obtains approximately 18% improvement in the modulation bandwidth from the annealed QD lasers. In addition, the modulation efficiency of the annealed QD lasers improves by approximately 45% as compared to the as-grown ones. The observed improvements are due to (1) the removal of defects which act as nonradiative recombination centers in the QD structure and (2) the reduction in the Auger-related recombination processes upon annealing

    Ell3 Enhances Differentiation of Mouse Embryonic Stem Cells by Regulating Epithelial-Mesenchymal Transition and Apoptosis

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    Ell3 is a testis-specific RNA polymerase II elongation factor whose cellular function is not clear. The present study shows that Ell3 is activated during the differentiation of mouse embryonic stem cells (mESCs). Furthermore, Ell3 plays a critical role in stimulating lineage differentiation of mESCs by promoting epithelial-mesenchymal transition (EMT) and suppressing apoptosis. Mouse ESCs engineered to stably express Ell3 were rapidly differentiated compared with control cells either under spontaneous differentiation or neural lineage-specific differentiation conditions. Gene expression profile and quantitative RT-PCR analysis showed that the expression of EMT markers, such as Zeb1 and Zeb2, two major genes that regulate EMT, was upregulated in Ell3-overexpressing mESCs. Remarkably, knockdown of Zeb1 attenuated the enhanced differentiation capacity of Ell3-overexpressing mESCs, which indicates that Ell3 plays a role in the induction of mESC differentiation by inducing EMT. In contrast to Ell3-overexpressing mESCs, Ell3-knock down mESCs could not differentiate under differentiation conditions and, instead, underwent caspase-dependent apoptosis. In addition, apoptosis of differentiating Ell3-knock out mESCs was associated with enhanced expression of p53. The present results suggest that Ell3 promotes the differentiation of mESCs by activating the expression of EMT-related genes and by suppressing p53 expression

    High-dose clevudine impairs mitochondrial function and glucose-stimulated insulin secretion in INS-1E cells

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    <p>Abstract</p> <p>Background</p> <p>Clevudine is a nucleoside analog reverse transcriptase inhibitor that exhibits potent antiviral activity against hepatitis B virus (HBV) without serious side effects. However, mitochondrial myopathy has been observed in patients with chronic HBV infection taking clevudine. Moreover, the development of diabetes was recently reported in patients receiving long-term treatment with clevudine. In this study, we investigated the effects of clevudine on mitochondrial function and insulin release in a rat clonal β-cell line, INS-1E.</p> <p>Methods</p> <p>The mitochondrial DNA (mtDNA) copy number and the mRNA levels were measured by using quantitative PCR. MTT analysis, ATP/lactate measurements, and insulin assay were performed.</p> <p>Results</p> <p>Both INS-1E cells and HepG2 cells, which originated from human hepatoma, showed dose-dependent decreases in mtDNA copy number and cytochrome c oxidase-1 (Cox-1) mRNA level following culture with clevudine (10 μM-1 mM) for 4 weeks. INS-1E cells treated with clevudine had reduced total mitochondrial activities, lower cytosolic ATP contents, enhanced lactate production, and more lipid accumulation. Insulin release in response to glucose application was markedly decreased in clevudine-treated INS-1E cells, which might be a consequence of mitochondrial dysfunction.</p> <p>Conclusions</p> <p>Our data suggest that high-dose treatment with clevudine induces mitochondrial defects associated with mtDNA depletion and impairs glucose-stimulated insulin secretion in insulin-releasing cells. These findings partly explain the development of diabetes in patients receiving clevudine who might have a high susceptibility to mitochondrial toxicity.</p

    Search for sterile neutrino oscillation using RENO and NEOS data

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    We present a reactor model independent search for sterile neutrino oscillation using 2\,509\,days of RENO near detector data and 180 days of NEOS data. The reactor related systematic uncertainties are significantly suppressed as both detectors are located at the same reactor complex of Hanbit Nuclear Power Plant. The search is performed by electron antineutrino\,(νe\overline{\nu}_e) disappearance between six reactors and two detectors with baselines of 294\,m\,(RENO) and 24\,m\,(NEOS). A spectral comparison of the NEOS prompt-energy spectrum with a no-oscillation prediction from the RENO measurement can explore reactor νe\overline{\nu}_e oscillations to sterile neutrino. Based on the comparison, we obtain a 95\% C.L. excluded region of 0.1<Δm412<70.1<|\Delta m_{41}^2|<7\,eV2^2. We also obtain a 68\% C.L. allowed region with the best fit of Δm412=2.41±0.03|\Delta m_{41}^2|=2.41\,\pm\,0.03\,\,eV2^2 and sin22θ14\sin^2 2\theta_{14}=0.08±\,\pm\,0.03 with a p-value of 8.2\%. Comparisons of obtained reactor antineutrino spectra at reactor sources are made among RENO, NEOS, and Daya Bay to find a possible spectral variation.Comment: 6 pages, 5 figures: This manuscript has been significantly revised by the joint reanalysis by RENO and NEOS Collaborations. (In the previous edition, the RENO collaboration used publicly available NEOS data to evaluate the expected neutrino spectrum at NEOS.
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