4,055 research outputs found

    Responses of seasonal indicators to extreme droughts in southwest China

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    Significant impact of extreme droughts on human society and ecosystem has occurred in many places of the world, for example, Southwest China (SWC). Considerable research concentrated on analyzing causes and effects of droughts in SWC, but few studies have examined seasonal indicators, such as variations of surface water and vegetation phenology. With the ongoing satellite missions, more and more earth observation data become available to environmental studies. Exploring the responses of seasonal indicators from satellite data to drought is helpful for the future drought forecast and management. This study analyzed the seasonal responses of surface water and vegetation phenology to drought in SWC using the multi-source data including Seasonal Water Area (SWA), Permanent Water Area (PWA), Start of Season (SOS), End of Season (EOS), Length of Season (LOS), precipitation, temperature, solar radiation, evapotranspiration, the Palmer Drought Severity Index (PDSI), the Normalized Difference Vegetation Index (NDVI), the Enhanced Vegetation Index (EVI), Gross Primary Productivity (GPP) and data from water conservancy construction. The results showed that SWA and LOS effectively revealed the development and recovery of droughts. There were two obvious drought periods from 2000 to 2017. In the first period (from August 2003 to June 2007), SWA decreased by 11.81% and LOS shortened by 5 days. They reduced by 21.04% and 9 days respectively in the second period (from September 2009 to June 2014), which indicated that there are more severe droughts in the second period. The SOS during two drought periods delayed by 3~6 days in spring, while the EOS advanced 1~3 days in autumn. All of PDSI, SWA and LOS could reflect the period of droughts in SWC, but the LOS and PDSI were very sensitive to the meteorological events, such as precipitation and temperature, while the SWA performed a more stable reaction to drought and could be a good indicator for the drought periodicity. This made it possible for using SWA in drought forecast because of the strong correlation between SWA and drought. Our results improved the understanding of seasonal responses to extreme droughts in SWC, which will be helpful to the drought monitoring and mitigation for different seasons in this ecologically fragile region

    Magnetic properties of undoped Cu2O fine powders with magnetic impurities and/or cation vacancies

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    Fine powders of micron- and submicron-sized particles of undoped Cu2O semiconductor, with three different sizes and morphologies have been synthesized by different chemical processes. These samples include nanospheres 200 nm in diameter, octahedra of size 1 micron, and polyhedra of size 800 nm. They exhibit a wide spectrum of magnetic properties. At low temperature, T = 5 K, the octahedron sample is diamagnetic. The nanosphere is paramagnetic. The other two polyhedron samples synthesized in different runs by the same process are found to show different magnetic properties. One of them exhibits weak ferromagnetism with T_C = 455 K and saturation magnetization, M_S = 0.19 emu/g at T = 5 K, while the other is paramagnetic. The total magnetic moment estimated from the detected impurity concentration of Fe, Co, and Ni, is too small to account for the observed magnetism by one to two orders of magnitude. Calculations by the density functional theory (DFT) reveal that cation vacancies in the Cu2O lattice are one of the possible causes of induced magnetic moments. The results further predict that the defect-induced magnetic moments favour a ferromagnetically coupled ground state if the local concentration of cation vacancies, n_C, exceeds 12.5%. This offers a possible scenario to explain the observed magnetic properties. The limitations of the investigations in the present work, in particular in the theoretical calculations, are discussed and possible areas for further study are suggested.Comment: 20 pages, 5 figures 2 tables, submitted to J Phys Condense Matte

    Family, Community, and a Life of Politics

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    A first-person narrative about life in Dayton, Ohio, composed as part of the Facing Project, a nationwide storytelling initiative

    Identification of New Delhi Metallo-β-lactamase 1 in Acinetobacter lwoffii of Food Animal Origin

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    Background To investigate the presence of metallo-β-lactamase (MBL) genes and the genetic environment of the New Delhi metallo-β-lactamase gene blaNDM-1 in bacteria of food animal origin. Methodology/Principal Findings Gram-negative bacteria with low susceptibility to imipenem (MIC\u3e8 µg/mL) were isolated from swab samples collected from 15 animal farms and one slaughterhouse in eastern China. These bacteria were selected for phenotypic and molecular detection of known MBL genes and antimicrobial susceptibility testing. For the blaNDM-1 positive isolate, conjugation and transformation experiments were carried out to assess plasmid transfer. Southern blotting was conducted to localize the blaNDM-1 genes, and DNA sequencing was performed to determine the sequences of blaNDM-1 and the flanking genes. In total, nine Gram-negative bacteria of four different species presented a MBL phenotype. blaNDM-1 was identified on a mobile plasmid named pAL-01 in an Acinetobacter lwoffii isolate of chicken origin. Transfer of pAL-01 from this isolate to E. coli J53 and JM109 resulted in resistance to multiple β-lactams. Sequence analysis revealed that the blaNDM-1 gene is attached to an intact insertion element ISAba125, whose right inverted repeat (IR-R) overlaps with the promoter sequence of blaNDM-1. Thus, insertion of ISAba125 likely enhances the expression of blaNDM-1. Conclusion The identification of a blaNDM-1- carrying strain of A. lwoffii in chickens suggests the potential for zoonotic transmission of blaNDM-1 and has important implications for food safety

    The role of basic health insurance on depression: an epidemiological cohort study of a randomized community sample in Northwest China

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    BACKGROUND: Little research has focused on the relationship between health insurance and mental health in the community. The objective of this study is to determine how the basic health insurance system influences depression in Northwest China. METHODS: Participants were selected from 32 communities in two northwestern Chinese cities through a three-stage random sampling. Three waves of interviews were completed in April 2006, December 2006, and January 2008. The baseline survey was completed by 4,079 participants. Subsequently, 2,220 participants completed the first follow-up, and 1,888 completed the second follow-up. Depression symptoms were measured by the Center for Epidemiologic Studies Depression Scale (CES-D). RESULTS: A total of 40.0% of participants had at least one form of health insurance. The percentages of participants with severe depressive symptoms in the three waves were 21.7%, 22.0%, and 17.6%. Depressive symptoms were found to be more severe among participants without health insurance in the follow-up surveys. After adjusting for confounders, participants without health insurance were found to experience a higher risk of developing severe depressive symptoms than participants with health insurance (7 months: OR, 1.40; 95% CI, 1.09-1.82; p = 0.01; 20 months: OR, 1.89; 95% CI, 1.37-2.61; p < 0.001). CONCLUSION: A lack of basic health insurance can dramatically increase the risk of depression based on northwestern Chinese community samples

    Study on the effect and mechanism of Lacticaseibacillus rhamnosus AFY06 on inflammation-associated colorectal cancer induced by AOM/DSS in mice

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    IntroductionLacticaseibacillus rhamnosus AFY06 (LR-AFY06) is a microorganism isolated from naturally fermented yogurt in Xinjiang, China.MethodsIn this study, we investigated the effects and mechanisms of LR-AFY06 in a mouse model of inflammation-associated colon cancer. The mouse model was established by azoxymethane/dextran sulfate sodium (AOM/DSS) induction. The tumor number in intestinal tissues was counted, and the histopathological analysis was performed on colon tissues. Enzyme-linked immunosorbent assay and real-time quantitative polymerase chain reaction were performed to measure relevant protein levels in colon tissues.ResultsLR-AFY06 treatment alleviated weight loss, increased organ index, reduced intestinal tumor incidence, improved histopathological damage, decreased the levels of inflammatory cytokines such as interleukin-6 (IL-6), interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), nuclear factor κB (NF-κB), and inducible nitric oxide synthase (iNOS) in the serum and colon tissue, downregulated the mRNA expression of inhibitor of NF-κB beta (IκBβ), p65, p50, p52, B-cell lymphoma-2 (Bcl-2), and B-cell lymphoma-extra large (Bcl-xL) in colon tissues, and increased the mRNA expression of Bid and caspase-8. The high concentration of LR-AFY06 exerted a better effect than the low concentration; however, the effect was slightly inferior to that of aspirin. Moreover, LR-AFY06 mitigated the intestinal inflammatory process and inhibited intestinal tumor development by regulating the NF-κB and apoptosis pathways.DiscussionThe present study indicates the regulatory potential of LR-AFY06 in inflammation-associated colorectal cancer in mice, providing a valuable basis for further research

    Ultrabroadband mid-infrared emission from Cr 2+ -doped infrared transparent chalcogenide glass ceramics embedded with thermally grown ZnS nanorods

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    We report, for the first time to our knowledge, an ultrabroadband mid-infrared (MIR) emission in the range of 1800–2800 nm at room temperature from a Cr2+-doped chalcogenide glass ceramic embedded with pure hexagonal (wurtzite) β-ZnS nanorods and study the emission-dependent properties on the doping concentration of Cr2+. A new family of chalcogenide glasses based on (100 − x) Ge1.5As2S6.5 – x ZnSe (in mol.%) was prepared by melt-quenching method. The Cr2+: β-ZnS nanorods of ˜150 nm in diameter and ˜1 μm in length were grown in the Cr2+-doped glass after thermal annealing. The compositional variations of glass structures and optical properties were studied. The crystalline phase, morphology of the thermally grown nanorods, and the microscopic elemental distributions were characterized using advanced nanoscale transmission electron microscopy analyses

    Tunnel Portal Construction using Sequential Excavation Method: A Case Study

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    Portal excavation in soft rock is one of the most challenging tasks in the construction of underground facilities. Significant convergence, collapses and surface settlement are usually associated with portal construction. Alluvium is loose unconsolidated material and most often tunnels constructed through tend to destabilize. In this study, portal excavation design has been analyzed using the finite element based computer program known as Phase2. The method of top heading and benching was not a suitable approach, keeping in view the previous experience. Subsequently, a different design of sequential excavation method (SEM) was proposed. Minimum convergence, minimum surface settlement, and machinery constraints were considered to be the vital importance for selection of final design. The results of finite element method (FEM) analysis showed that the finally selected SEM design has a roof convergence of 4 mm for the heading and full face excavation has 25 mm. These values were comparable with the ones obtained from a 5-pin convergence station, installed during the portal excavation (0.5 m inside from the portal). No or very little surface settlement was shown by the numerical model and actual field observation. Consequently, a proper SEM design based on numerical modeling allowed a successful construction of a large portal in alluvial deposits
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