347 research outputs found

    Scrutinizing the η-η′ mixing, masses and pseudoscalar decay constants in the framework of U(3) chiral effective field theory

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    Journal of High Energy Physics 2015.6 (2015): 175 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)We study the η-η′ mixing up to next-to-next-to-leading-order in U(3) chiral perturbation theory in the light of recent lattice simulations and phenomenological inputs. A general treatment for the η-η′ mixing at higher orders, with the higher-derivative, kinematic and mass mixing terms, is addressed. The connections between the four mixing parameters in the two-mixing-angle scheme and the low energy constants in the U(3) chiral effective theory are provided both for the singlet-octet and the quark-flavor bases. The axial-vector decay constants of pion and kaon are studied in the same order and confronted with the lattice simulation data as well. The quark-mass dependences of mη, mη ′ and mK are found to be well described at next-to-leading order. Nonetheless, in order to simultaneously describe the lattice data and phenomenological determinations for the properties of light pseudoscalars π, K, η and η′, the next-to-next-to-leading order study is essential. Furthermore, the lattice and phenomenological inputs are well reproduced for reasonable values of low the energy constants, compatible with previous bibliographyWe thank Shao-Zhou Jiang for communication on the updated values of the O(p6)LECs. This work is supported in part by the National Natural Science Foundation of China (NSFC) under Grant No. 11105038, the Natural Science Foundation of Hebei Province with contract No. A2015205205, the grants from the Education Department of Hebei Province under contract No. YQ2014034, the grants from the Department of Human Resources and Social Security of Hebei Province with contract No. C201400323, and the Doctor Foundation of Hebei Normal University under Contract No. L2010B04, the Spanish Government (MINECO) and the European Commission (ERDF) [FPA2010-17747, FPA2013-44773-P, FPA2013-40483-P, SEV-2012-0249 (Severo Ochoa Program), CSD2007-00042 (Consolider Project CPAN)], the grants with contract No. FIS2014-57026-REDT from MINECO (Spain), and EPOS network of the European Community Research Infrastructure Integrating Activity “Study of Strongly Interacting Matter” (HadronPhysics3, Grant No. 283286

    A THEORETICAL ANALYSIS ON THE MODEL OF POROUS GAS DIFFUSION ELECTRODE

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    A theoretical discussion on the polarization of porous gas diffusion electrode considering the flooded catalytic agglomerates covered with nonuniform liquid film is presented. Electrochemical reaction, diffusion in gaseous phase, diffusion through liquid film and diffusion in agglomerates are considered simultaneously.The performances of the electrode can be predicted as functions of measurable electrode parameters—characteristic transport currents. Analytical solutions and digital simulations are given and compared with experimental results

    China’s urban methane emissions from municipal wastewater treatment plant

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    The increased number and capacity of municipal wastewater treatment plants (WWTPs) in China has driven the emission of methane (CH4). Few studies have focused on quantification of CH4 emissions from municipal WWTPs of different cities and analysis of socioeconomic factors influencing the quantity of emissions. Here we estimated CH4 emissions from WWTPs in China for 229 prefectural‐level cities, based on data from 2,019 working municipal WWTPs. The results show the total CH4 emissions to be 1,169.8 thousand tons (29.2 MtCO2e) in 2014, which is over three times that of the municipal WWTPs in the United States in 2016. Large cities along the east coast regions had larger CH4 emissions in absolute and per capita terms. Correlation analysis shows that cities with higher gross domestic product, household food consumption expenditure, or household consumption expenditure produced more degradable organics in wastewater, thus more CH4 emissions. Measures to control the sources of degradable organics and regulate WWTP processes with less emission factor are key to mitigate CH4 emissions. In addition to aerobic or anaerobic wastewater treatment systems, factors such as wastewater temperature, length of sewer, and the addition of nitrate that influencing emission factor are suggested to be involved in CH4 emission modeling

    Predicted Disappearance of Cephalantheropsis obcordata in Luofu Mountain Due to Changes in Rainfall Patterns

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    <div><h3>Background</h3><p>In the past century, the global average temperature has increased by approximately 0.74°C and extreme weather events have become prevalent. Recent studies have shown that species have shifted from high-elevation areas to low ones because the rise in temperature has increased rainfall. These outcomes challenge the existing hypothesis about the responses of species to climate change.</p> <h3>Methodology/Principal Findings</h3><p>With the use of data on the biological characteristics and reproductive behavior of <em>Cephalantheropsis obcordata</em> in Luofu Mountain, Guangdong, China, trends in the population size of the species were predicted based on several factors. The response of <em>C. obcordata</em> to climate change was verified by integrating it with analytical findings on meteorological data and an artificially simulated environment of water change. The results showed that <em>C. obcordata</em> can grow only in waterlogged streams. The species can produce fruit with many seeds by insect pollination; however, very few seeds can burgeon to become seedlings, with most of those seedlings not maturing into the sexually reproductive phase, and grass plants will die after reproduction. The current population's age pyramid is kettle-shaped; it has a Deevey type I survival curve; and its net reproductive rate, intrinsic rate of increase, as well as finite rate of increase are all very low. The population used in the artificial simulation perished due to seasonal drought.</p> <h3>Conclusions</h3><p>The change in rainfall patterns caused by climate warming has altered the water environment of <em>C. obcordata</em> in Luofu Mountain, thereby restricting seed burgeoning as well as seedling growth and shortening the life span of the plant. The growth rate of the <em>C. obcordata</em> population is in descending order, and models of population trend predict that the population in Luofu Mountain will disappear in 23 years.</p> </div

    A Gene Expression Signature of Acquired Chemoresistance to Cisplatin and Fluorouracil Combination Chemotherapy in Gastric Cancer Patients

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    We initiated a prospective trial to identify transcriptional alterations associated with acquired chemotherapy resistance from pre- and post-biopsy samples from the same patient and uncover potential molecular pathways involved in treatment failure to help guide therapeutic alternatives.A prospective, high-throughput transcriptional profiling study was performed using endoscopic biopsy samples from 123 metastatic gastric cancer patients prior to cisplatin and fluorouracil (CF) combination chemotherapy. 22 patients who initially responded to CF were re-biopsied after they developed resistance to CF. An acquired chemotherapy resistance signature was identified by analyzing the gene expression profiles from the matched pre- and post-CF treated samples. The acquired resistance signature was able to segregate a separate cohort of 101 newly-diagnosed gastric cancer patients according to the time to progression after CF. Hierarchical clustering using a 633-gene acquired resistance signature (feature selection at P<0.01) separated the 101 pretreatment patient samples into two groups with significantly different times to progression (2.5 vs. 4.7 months). This 633-gene signature included the upregulation of AKT1, EIF4B, and RPS6 (mTOR pathway), DNA repair and drug metabolism genes, and was enriched for genes overexpressed in embryonic stem cell signatures. A 72-gene acquired resistance signature (a subset of the 633 gene signature also identified in ES cell-related gene sets) was an independent predictor for time to progression (adjusted P = 0.011) and survival (adjusted P = 0.034) of these 101 patients.This signature may offer new insights into identifying new targets and therapies required to overcome the acquired resistance of gastric cancer to CF

    Cutting improves the productivity of lucerne-rich stands used in the revegetation of degraded arable land in a semi-arid environment

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    Understanding the relationships between vegetative and environmental variables is important for revegetation and ecosystem management on the Loess Plateau, China. Lucerne (Medicago sativa L.) has been widely used in the region to improve revegetation, soil and water conservation, and to enhance livestock production. However, there is little information on how environmental factors influence long-term succession in lucerne-rich vegetation. Our objective was to identify the main environmental variables controlling the succession process in lucerne-rich vegetation such that native species are not suppressed after sowing on the Loess Plateau. Vegetation and soil surveys were performed in 31 lucerne fields (three lucerne fields without any management from 2003-2013 and 28 fields containing 11-year-old lucerne with one cutting each year). Time after planting was the most important factor affecting plant species succession. Cutting significantly affected revegetation characteristics, such as aboveground biomass, plant density and diversity. Soil moisture content, soil organic carbon, soil available phosphorus and slope aspect were key environmental factors affecting plant species composition and aboveground biomass, density and diversity. Long-term cutting can cause self-thinning in lucerne, maintain the stability of lucerne production and slow its degradation. For effective management of lucerne fields, phosphate fertilizer should be applied and cutting performed

    Three-gene predictor of clinical outcome for gastric cancer patients treated with chemotherapy

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    To identify transcriptional profiles predictive of the clinical benefit of cisplatin and fluorouracil (CF) chemotherapy to gastric cancer patients, endoscopic biopsy samples from 96 CF-treated metastatic gastric cancer patients were prospectively collected before therapy and analyzed using high-throughput transcriptional profiling and array comparative genomic hybridization. Transcriptional profiling identified 917 genes that are correlated with poor patient survival after CF at P<0.05 (poor prognosis signature), in which protein synthesis and DNA replication/recombination/repair functional categories are enriched. A survival risk predictor was then constructed using genes, which are included in the poor prognosis signature and are contained within identified genomic amplicons. The combined expression of three genes—MYC, EGFR and FGFR2—was an independent predictor for overall survival of 27 CF-treated patients in the validation set (adjusted P=0.017), and also for survival of 40 chemotherapy-treated gastric cancer patients in a published data set (adjusted P=0.026). Thus, combined expression of MYC, EGFR and FGFR2 is predictive of poor survival in CF-treated metastatic gastric cancer patients

    An Inhibitory Effect of Extracellular Ca2+ on Ca2+-Dependent Exocytosis

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    Aim: Neurotransmitter release is elicited by an elevation of intracellular Ca 2+ concentration ([Ca 2+] i). The action potential triggers Ca 2+ influx through Ca 2+ channels which causes local changes of [Ca 2+] i for vesicle release. However, any direct role of extracellular Ca 2+ (besides Ca 2+ influx) on Ca 2+-dependent exocytosis remains elusive. Here we set out to investigate this possibility on rat dorsal root ganglion (DRG) neurons and chromaffin cells, widely used models for studying vesicle exocytosis. Results: Using photolysis of caged Ca 2+ and caffeine-induced release of stored Ca 2+, we found that extracellular Ca 2+ inhibited exocytosis following moderate [Ca 2+]i rises (2–3 mM). The IC50 for extracellular Ca 2+ inhibition of exocytosis (ECIE) was 1.38 mM and a physiological reduction (,30%) of extracellular Ca 2+ concentration ([Ca 2+]o) significantly increased the evoked exocytosis. At the single vesicle level, quantal size and release frequency were also altered by physiological [Ca 2+] o. The calcimimetics Mg 2+,Cd 2+, G418, and neomycin all inhibited exocytosis. The extracellular Ca 2+-sensing receptor (CaSR) was not involved because specific drugs and knockdown of CaSR in DRG neurons did not affect ECIE. Conclusion/Significance: As an extension of the classic Ca 2+ hypothesis of synaptic release, physiological levels of extracellular Ca 2+ play dual roles in evoked exocytosis by providing a source of Ca 2+ influx, and by directly regulatin
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