606 research outputs found
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
Biomarker-indicated extent of oxidation of plant-derived organic carbon (OC) in relation to geomorphology in an arsenic contaminated Holocene aquifer, Cambodia
The poisoning of rural populations in South and Southeast Asia due to high groundwater arsenic concentrations is one of the world’s largest ongoing natural disasters. It is important to consider environmental processes related to the release of geogenic arsenic, including geomorphological and organic geochemical processes. Arsenic is released from sediments when iron-oxide minerals, onto which arsenic is adsorbed or incorporated, react with organic carbon (OC) and the OC is oxidised. In this study we build a new geomorphological framework for Kandal Province, a highly studied arsenic affected region of Cambodia, and tie this into wider regional environmental change throughout the Holocene. Analyses shows that the concentration of OC in the sediments is strongly inversely correlated to grainsize. Furthermore, the type of OC is also related to grain size with the clay containing mostly (immature) plant derived OC and sand containing mostly thermally mature derived OC. Finally, analyses indicate that within the plant derived OC relative oxidation is strongly grouped by stratigraphy with the older bound OC more oxidised than younger OC
Retardation of arsenic transport through a Pleistocene aquifer
Groundwater drawn daily from shallow alluvial sands by millions of wells over large areas of south and southeast Asia exposes an estimated population of over a hundred million people to toxic levels of arsenic1. Holocene aquifers are the source of widespread arsenic poisoning across the region2, 3. In contrast, Pleistocene sands deposited in this region more than 12,000 years ago mostly do not host groundwater with high levels of arsenic. Pleistocene aquifers are increasingly used as a safe source of drinking water4 and it is therefore important to understand under what conditions low levels of arsenic can be maintained. Here we reconstruct the initial phase of contamination of a Pleistocene aquifer near Hanoi, Vietnam. We demonstrate that changes in groundwater flow conditions and the redox state of the aquifer sands induced by groundwater pumping caused the lateral intrusion of arsenic contamination more than 120 metres from a Holocene aquifer into a previously uncontaminated Pleistocene aquifer. We also find that arsenic adsorbs onto the aquifer sands and that there is a 16–20-fold retardation in the extent of the contamination relative to the reconstructed lateral movement of groundwater over the same period. Our findings suggest that arsenic contamination of Pleistocene aquifers in south and southeast Asia as a consequence of increasing levels of groundwater pumping may have been delayed by the retardation of arsenic transport.National Science Foundation (U.S.) (NSF grant EAR09-11557)Swiss Agency for Development and Cooperation (Grant NAFOSTED 105-09-59-09 to CETASD, the Centre for Environmental Technology and Sustainable Development (Vietnam))National Institute of Environmental Health Sciences (NIEHS grant P42 ES010349)National Institute of Environmental Health Sciences (NIEHS grant P42 ES016454
Causal Pathways from Enteropathogens to Environmental Enteropathy: Findings from the MAL-ED Birth Cohort Study
Background
Environmental enteropathy (EE), the adverse impact of frequent and numerous enteric infections on the gut resulting in a state of persistent immune activation and altered permeability, has been proposed as a key determinant of growth failure in children in low- and middle-income populations. A theory-driven systems model to critically evaluate pathways through which enteropathogens, gut permeability, and intestinal and systemic inflammation affect child growth was conducted within the framework of the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) birth cohort study that included children from eight countries.
Methods
Non-diarrheal stool samples (N = 22,846) from 1253 children from multiple sites were evaluated for a panel of 40 enteropathogens and fecal concentrations of myeloperoxidase, alpha-1-antitrypsin, and neopterin. Among these same children, urinary lactulose:mannitol (L:M) (N = 6363) and plasma alpha-1-acid glycoprotein (AGP) (N = 2797) were also measured. The temporal sampling design was used to create a directed acyclic graph of proposed mechanistic pathways between enteropathogen detection in non-diarrheal stools, biomarkers of intestinal permeability and inflammation, systemic inflammation and change in length- and weight- for age in children 0–2 years of age.
Findings
Children in these populations had frequent enteric infections and high levels of both intestinal and systemic inflammation. Higher burdens of enteropathogens, especially those categorized as being enteroinvasive or causing mucosal disruption, were associated with elevated biomarker concentrations of gut and systemic inflammation and, via these associations, indirectly associated with both reduced linear and ponderal growth. Evidence for the association with reduced linear growth was stronger for systemic inflammation than for gut inflammation; the opposite was true of reduced ponderal growth. Although Giardia was associated with reduced growth, the association was not mediated by any of the biomarkers evaluated.
Interpretation
The large quantity of empirical evidence contributing to this analysis supports the conceptual model of EE. The effects of EE on growth faltering in young children were small, but multiple mechanistic pathways underlying the attribution of growth failure to asymptomatic enteric infections had statistical support in the analysis. The strongest evidence for EE was the association between enteropathogens and linear growth mediated through systemic inflammation
Efficacy of Avicennia marina (Forsk.) Vierh. leaves extracts against some atmospheric fungi
Crude ethanolic extract of Avicennia marina leaves was tested against seven allergenic fungi viz., Alternaria alternata, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Cladosporium herbarum, Penicillium notatum and Saccharomyces cerevisiae using five different solvents: dimethyl sulphoxide (DMSO), distilled water (DW), chloroform, ethanol and acetone at 2000, 4000 and 6000 ppm doses. Dose dependent tendency in the increase or decrease in the growth of fungi was observed. Two synthetic drugs miconazole and amphotericin-B were used as positive control. Miconazole was 100% effective against A. alternata, C. herbatum, P. notatum and S. cerevisiae with the concentrations of 95.00 ± 1.62, 78.00 ± 4.99, 100.00 ± 0.69 and 110.00 ± 2.33 (μg/ml of SDA medium), respectively. Amphotericin-B completely controlled the growth of A. flavus, A. fumigatus and A. niger in the concentration of 24.00 ± 17.00, 30.00 ± 15.66 and 18.00 ± 18.34 (μg/ml of SDA medium), respectively. Distilled water and DMSO were considered to be the most effective solvents preventing 83.00 ± 4.73% growth of A. niger, 80.33 ± 5.60% A. flavus, 78.58 ± 3.18% A. alternata, 72.91 ± 7.96% P. notatum, 65.25 ± 3.55% C. herbarum, 63.25 ± 4.52% A. fumigatus and 48.5 ± 7.89% S. cerevisiae. Statistically, the results were compared with negative control and found to be highly significant (p<0.01).Key words: Allergenic fungi, inhibition, dose dependent, growth control, synthetic drugs
Measurement of the t¯tZ and t¯tW cross sections in proton-proton collisions at √s=13 TeV with the ATLAS detector
A measurement of the associated production of a top-quark pair (t¯t) with a vector boson (W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented, using 36.1 fb−1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. Events are selected in channels with two same- or opposite-sign leptons (electrons or muons), three leptons or four leptons, and each channel is further divided into multiple regions to maximize the sensitivity of the measurement. The t¯tZ and t¯tW production cross sections are simultaneously measured using a combined fit to all regions. The best-fit values of the production cross sections are σt¯tZ=0.95±0.08stat±0.10syst pb and σt¯tW=0.87±0.13stat±0.14syst pb in agreement with the Standard Model predictions. The measurement of the t¯tZ cross section is used to set constraints on effective field theory operators which modify the t¯tZ vertex
Performance of missing transverse momentum reconstruction with the ATLAS detector using proton–proton collisions at √s = 13 TeV
The performance of the missing transverse momentum (EmissT) reconstruction with the ATLAS detector is evaluated using data collected in proton–proton collisions at the LHC at a centre-of-mass energy of 13 TeV in 2015. To reconstruct EmissT, fully calibrated electrons, muons, photons, hadronically decaying τ -leptons, and jets reconstructed from calorimeter energy deposits and charged-particle tracks are used. These are combined with the soft hadronic activity measured by reconstructed charged-particle tracks not associated with the hard objects. Possible double counting of contributions from reconstructed charged-particle tracks from the inner detector, energy deposits in the calorimeter, and reconstructed muons from the muon spectrometer is avoided by applying a signal ambiguity resolution procedure which rejects already used signals when combining the various EmissT contributions. The individual terms as well as the overall reconstructed EmissT are evaluated with various performance metrics for scale (linearity), resolution, and sensitivity to the data-taking conditions. The method developed to determine the systematic uncertainties of the EmissT scale and resolution is discussed. Results are shown based on the full 2015 data sample corresponding to an integrated luminosity of 3.2 fb−1
Combined measurement of differential and total cross sections in the H → γγ and the H → ZZ* → 4ℓ decay channels at s=13 TeV with the ATLAS detector
A combined measurement of differential and inclusive total cross sections of Higgs boson production is performed using 36.1 fb−1 of 13 TeV proton–proton collision data produced by the LHC and recorded by the ATLAS detector in 2015 and 2016. Cross sections are obtained from measured H→γγ and H→ZZ*(→4ℓ event yields, which are combined taking into account detector efficiencies, resolution, acceptances and branching fractions. The total Higgs boson production cross section is measured to be 57.0−5.9 +6.0 (stat.) −3.3 +4.0 (syst.) pb, in agreement with the Standard Model prediction. Differential cross-section measurements are presented for the Higgs boson transverse momentum distribution, Higgs boson rapidity, number of jets produced together with the Higgs boson, and the transverse momentum of the leading jet. The results from the two decay channels are found to be compatible, and their combination agrees with the Standard Model predictions
Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.
Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability
Characterization of Cr(VI)-reducing indigenous bacteria from a long-term tannery waste-contaminated soil
This paper investigated the Cr (VI) detoxification potential of 4 novel bacterial strains isolated from a long-term tannery waste-contaminated soil. Molecular techniques were used to identify the bacterial strains using 16 S rDNA gene sequencing. The Cr (VI) detoxification capacity of the bacteria was determined by 1,5-diphenylcarbazide (DPC) methods. The identified bacterial strains were Bacillus subterraneus MMKT-10, Klebsiella quasivariicola MMKT-15, Acinetobacter seohaensis MMKT-19, and Staphylococcus saprophyticus MMKT-25. All the strains showed maximum tolerance concentration (MTC) of Cr (VI) up to 4000 mg/L. However, in terms of Cr(VI) reduction rate, K. quasivariicola can be considered the most efficient, reducing the two preliminary Cr(VI) concentrations (10 and 20 mg/L) at 15 and 18 h, respectively, while the rest of the strains needed 30 h to reduce the same concentrations from the culture medium. The favorable temperature for Cr(VI) detoxification ranged from 30–40 °C. However, 100 % Cr (VI) reduction was achieved by all the strains at 35 0C. Interestingly, all the bacterial strains reduced a significant amount of Cr (VI) at 50 0C, indicative of their thermotolerant nature. The ideal pH for Cr (VI) reduction was 7 for B. subterraneus MMKT-10 and K. quasivariicola MMKT-15, whereas it was 8 for Acinetobacter seohaensis MMKT-19 and Staphylococcus saprophyticus MMKT-25. The indigenous bacterial strains isolated in this study could be one of the promising candidates for the detoxification of Cr (VI) contaminated sites
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