1,707 research outputs found

    Nitrogen release kinetics of organic nutrient sources in two benchmark soils of Indo-Gangetic plains

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    An understanding of the mineralization process of organic amendments in soil is required to synchronize N release with crop demand and protect the environment from excess N accumulation. Therefore, we conducted a laboratory incubation experiment to assess nitrogen mineralization potential of crop residues (rice and wheat straw) and organic manures (poultry manure, farmyard manure, cowpea and sesbania) in two benchmark soils (Typic Haplustept and Typic Ustifluvents) of semi-arid region of Punjab, India, varying in textureat field capacity moisture level at a constant temperature of 331°C. Mineralization was faster during first 7 days of incubation in Typic Haplustept and upto 14 days in Typic Ustifluvents which subsequently declined over time. In both soils, net N mineralization continued to increase with increasing period of incubation (expect with crop residues) and was significantly higher in Typic Ustifluvents (54-231µg g-1) than Typic Haplustept (33-203 µg g-1). Compared to unamended soils, percent N mineralized was highest is sesbania (35-40 %) followed by cowpea (32-37 %) and least in wheat (10-11 %) after 42 days of incubation. Thus, sesbania and cowpea may preferably be used to meetthe large N demand during early period of plant growth. Further, mineralization rate constants (k) also indicated that availability of mineral N was significantly higher with application of organic amendments than unamended control treatments in both soils. Therefore, it may be concluded that considerable economy in the use of inorganic N fertilizer can be employed if N mineralization potential of organic inputs is taken into consideration

    Trans-cerebral HCO3- and PCO2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans

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    This study investigated trans-cerebral internal jugular venous-arterial bicarbonate ([HCO(3)(−)]) and carbon dioxide tension (PCO(2)) exchange utilizing two separate interventions to induce acidosis: 1) acute respiratory acidosis via elevations in arterial PCO(2) (PaCO(2)) (n = 39); and 2) metabolic acidosis via incremental cycling exercise to exhaustion (n = 24). During respiratory acidosis, arterial [HCO(3)(−)] increased by 0.15 ± 0.05 mmol ⋅ l(−1) per mmHg elevation in PaCO(2) across a wide physiological range (35 to 60 mmHg PaCO(2); P < 0.001). The narrowing of the venous-arterial [HCO(3)(−)] and PCO(2) differences with respiratory acidosis were both related to the hypercapnia-induced elevations in cerebral blood flow (CBF) (both P < 0.001; subset n = 27); thus, trans-cerebral [HCO(3)(−)] exchange (CBF × venous-arterial [HCO(3)(−)] difference) was reduced indicating a shift from net release toward net uptake of [HCO(3)(−)] (P = 0.004). Arterial [HCO(3)(−)] was reduced by −0.48 ± 0.15 mmol ⋅ l(−1) per nmol ⋅ l(−1) increase in arterial [H(+)] with exercise-induced acidosis (P < 0.001). There was no relationship between the venous-arterial [HCO(3)(−)] difference and arterial [H(+)] with exercise-induced acidosis or CBF; therefore, trans-cerebral [HCO(3)(−)] exchange was unaltered throughout exercise when indexed against arterial [H(+)] or pH (P = 0.933 and P = 0.896, respectively). These results indicate that increases and decreases in systemic [HCO(3)(−)] – during acute respiratory/exercise-induced metabolic acidosis, respectively – differentially affect cerebrovascular acid-base balance (via trans-cerebral [HCO(3)(−)] exchange)

    An Introduction to Propensity Score Methods for Reducing the Effects of Confounding in Observational Studies

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    The propensity score is the probability of treatment assignment conditional on observed baseline characteristics. The propensity score allows one to design and analyze an observational (nonrandomized) study so that it mimics some of the particular characteristics of a randomized controlled trial. In particular, the propensity score is a balancing score: conditional on the propensity score, the distribution of observed baseline covariates will be similar between treated and untreated subjects. I describe 4 different propensity score methods: matching on the propensity score, stratification on the propensity score, inverse probability of treatment weighting using the propensity score, and covariate adjustment using the propensity score. I describe balance diagnostics for examining whether the propensity score model has been adequately specified. Furthermore, I discuss differences between regression-based methods and propensity score-based methods for the analysis of observational data. I describe different causal average treatment effects and their relationship with propensity score analyses

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

    Methods for specifying the target difference in a randomised controlled trial : the Difference ELicitation in TriAls (DELTA) systematic review

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    Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

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    A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino
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