479 research outputs found
Enhanced surface acceleration of fast electrons by using sub-wavelength grating targets
Surface acceleration of fast electrons in intense laser-plasma interaction is
improved by using sub-wavelength grating targets. The fast electron beam
emitted along the target surface was enhanced by more than three times relative
to that by using planar target. The total number of the fast electrons ejected
from the front side of target was also increased by about one time. The method
to enhance the surface acceleration of fast electron is effective for various
targets with sub-wavelength structured surface, and can be applied widely in
the cone-guided fast ignition, energetic ion acceleration, plasma device, and
other high energy density physics experiments.Comment: 14 pages, 4figure
Corrigendum: Dauricine attenuates vascular endothelial inflammation through inhibiting NF-ÎșB pathway
Renewal management framework for urban rail transit assets
Decision-making surrounding asset renewal is essential for the efficient use of renewal resources and safe operation of urban rail transit. In this study, major problems in the current management of urban rail industries in countries with the same problems as those in China were analysed, and in response, a renewal management framework based on service life estimation was proposed to provide adequate decision-making support for urban rail transit assets. In this framework, the cumulative failure frequency of an asset is used to indicate its health condition, and considering the uncertainties and heterogeneities in the deterioration process of assets, a PoissonâWeibull process model-based methodology was developed to estimate the service and residual lives of each asset, which are then employed in analysing its renewal demand and renewal period. Finally, the model is validated through an empirical study of rail renewal in the Beijing Metro. Our evaluation demonstrates that the proposed framework can estimate each assetâs service life accurately and can be used by asset management personnel to establish reasonable renewal plans and provide decision-making support for a scientifically informed resource allocation, thus mitigating major problems in current management practices
Dauricine Attenuates Vascular Endothelial Inflammation Through Inhibiting NF-ÎșB Pathway
Endothelial cells are the fundamental components of blood vessels that regulate several physiological processes including immune responses, angiogenesis, and vascular tone. Endothelial dysfunction contributes to the development of various diseases such as acute lung injury, and endothelial inflammation is a vital part of endothelial dysfunction. Dauricine is an extract isolated from Menispermum dauricum DC, a traditional Chinese medical plant that can be used for pharyngitis. In this work, we found that IL-1ÎČ-induced overexpression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin was inhibited by dauricine in primary human umbilical vein endothelial cells (HUVECs). Correspondingly, adhesion of human acute monocytic leukemia cell line (THP-1) to HUVECs was decreased by dauricine. Further studies showed that dauricine inhibited the activation of nuclear factor-ÎșB (NF-ÎșB) pathway in HUVECs stimulated with IL-1ÎČ. In vivo, dauricine protected mice from lipopolysaccharide (LPS)-induced acute lung injury. In lung tissues, the activation of NF-ÎșB pathway and the expression of its downstream genes (ICAM-1, VCAM-1, and E-selectin) were decreased by dauricine, consistent with what was found in vitro. In summary, we concluded that dauricine could alleviate endothelial inflammation by suppressing NF-ÎșB pathway, which might serve as an effective candidate for diseases related with endothelial inflammation
Climatology and Change of Extreme Precipitation Events in Taiwan Based on Weather Types
Taiwan\u27s most significant natural hazards are caused by hydrological extremes resulting from excessive precipitation. The threat of extreme precipitation is posed by several different types of weather patterns that affect Taiwan. This study examined the biâdecadal changes in rainfall by defining an extreme precipitation occurrence (EPO) for a range of event durations from 1 to 24âhr. Three major weather types affecting EPO in Taiwan were identified from 1993 to 2015: the front type consisting of either a frontal zone or convective systems developing with an apparent Meiyu cloudband, diurnal rainfall events when no apparent synoptic features are present, and a tropical cyclone (TC) type according to the maximum sustained wind radius of a TC. Results show that TCâtype events have the greatest overall contribution to EPO at longer (\u3e6 hr) durations. Diurnal/afternoon convection events contribute most to the shorter (\u3c3 hr) duration EPO, while frontal/Meiyu systems prevail in the medium (3â6 hr) duration. EPO of almost all durations have experienced an increase, with the 3â and 12âhr EPO having increased by 4.6 days each over the 23âyears. However, apparent decadalâscale variability exists in these EPO associated with the decreasing tendency of EPO after the midâ2000s, particularly the longer duration (\u3e6 hr) EPO associated with the TCâtype events in summer. The distinction between EPO trends for the entire island of Taiwan and for the Taipei metropolitan area alone (northern Taiwan, population of 7 million) were compared, and an intriguing interannual variation is reported in the TCâtype EPO associated with the TC season 1âyear to a year and half just before an El NiñoâSouthern Oscillation event. The analysis here provides refined statistical distributions of extreme rainfall, and these can contribute to the revision of governmental definitions for weather disasters that are used in mitigation and response strategies
Effects of isospin and momentum dependent interactions on liquid-gas phase transition in hot asymmetric nuclear matter
The liquid-gas phase transition in hot neutron-rich nuclear matter is
investigated within a self-consistent thermal model using an isospin and
momentum dependent interaction (MDI) constrained by the isospin diffusion data
in heavy-ion collisions, a momentum-independent interaction (MID), and an
isoscalar momentum-dependent interaction (eMDYI). The boundary of the
phase-coexistence region is shown to be sensitive to the density dependence of
the nuclear symmetry energy with a softer symmetry energy giving a higher
critical pressure and a larger area of phase-coexistence region. Compared with
the momentum-independent MID interaction, the isospin and momentum-dependent
MDI interaction is found to increase the critical pressure and enlarge the area
of phase-coexistence region. For the isoscalar momentum-dependent eMDYI
interaction, a limiting pressure above which the liquid-gas phase transition
cannot take place has been found and it is shown to be sensitive to the
stiffness of the symmetry energy.Comment: 6 pages, 4 figures, revised version, to appear in PL
18F-FDG PET/CT-based gross tumor volume definition for radiotherapy in head and neck Cancer: a correlation study between suitable uptake value threshold and tumor parameters
<p>Abstract</p> <p>Background</p> <p>To define a suitable threshold setting for gross tumor volume (GTV) when using <sup>18</sup>Fluoro-deoxyglucose positron emission tomography and computed tomogram (PET/CT) for radiotherapy planning in head and neck cancer (HNC).</p> <p>Methods</p> <p>Fifteen HNC patients prospectively received PET/CT simulation for their radiation treatment planning. Biological target volume (BTV) was derived from PET/CT-based GTV of the primary tumor. The BTVs were defined as the isodensity volumes when adjusting different percentage of the maximal standardized uptake value (SUVmax), excluding any artifact from surrounding normal tissues. CT-based primary GTV (C-pGTV) that had been previously defined by radiation oncologists was compared with the BTV. Suitable threshold level (sTL) could be determined when BTV value and its morphology using a certain threshold level was observed to be the best fitness of the C-pGTV. Suitable standardized uptake value (sSUV) was calculated as the sTL multiplied by the SUVmax.</p> <p>Results</p> <p>Our result demonstrated no single sTL or sSUV method could achieve an optimized volumetric match with the C-pGTV. The sTL was 13% to 27% (mean, 19%), whereas the sSUV was 1.64 to 3.98 (mean, 2.46). The sTL was inversely correlated with the SUVmax [sTL = -0.1004 Ln (SUVmax) + 0.4464; R<sup>2 </sup>= 0.81]. The sSUV showed a linear correlation with the SUVmax (sSUV = 0.0842 SUVmax + 1.248; R<sup>2 </sup>= 0.89). The sTL was not associated with the value of C-pGTVs.</p> <p>Conclusion</p> <p>In PET/CT-based BTV for HNC, a suitable threshold or SUV level can be established by correlating with SUVmax rather than using a fixed threshold.</p
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