328 research outputs found

    Early Carnian conodont fauna at Yongyue, Zhenfeng area and its implication for Ladinian-Carnian subdivision in Guizhou, South China

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    The subdivision of Ladinian and Carnian strata in Guizhou, South China has been a matter of intense debate because of the paucity of age-diagnostic faunas. Here we have carried out a detailed conodont biostratigraphic investigation on the Yangliujing, Zhuganpo and Wayao formations in the Yongyue section of western Guizhou Province. Conodonts are only prolific in the Zhuganpo and Wayao formations. Three genera and twenty species are identified, including two new species Quadralella wanlanensis n. sp. and Quadralella yongyueensis n. sp. They represent a rather endemic fauna of latest Ladinian to early Carnian age. Four conodont zones are established. They are, in the ascending order, the Paragondolella foliata, Quadralella polygnathiformis, Quadralella tadpole, and Quadralella aff. praelindae zones. Thus in the study area, the Zhuganpo Formation is generally of early Carnian (Julian 1) age whilst the Wayao Formation probably extends from the Julian 2 into the late Carnian (Tuvalian substage). The Ladinian–Carnian boundary (LCB) cannot be precisely defined due to the absence of the ammonoid Daxatina Canadensis and the paucity of conodonts. However, the LCB is unlikely lower than the Yangliujing–Zhuganpo formation contact. The Julian 1–Julian 2 (early Carnian) substages boundary is defined in the uppermost Zhuganpo Formation by the occurrence of basal Julian 2 ammonoid Austrotrachyceras ex gr. A. austriacum and is also evidenced by the disappearance of most short-range Julian 1 conodonts in the overlying Wayao Formation

    Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

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    Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization

    Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

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    We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

    Saethre-Chotzen syndrome : cranofacial anomalies caused by genetic changes in the TWIST gene

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    In this thesis, one of the most frequently occurring and most variable craniosynostosis syndromes was investigated; Saethre-Chotzen syndrome. Craniosynostosis is the premature obliteration of cranial sutures in the developing embryo. It can also occur in the first few months of life. Saethre-Chotzen syndrome is, besides craniosynostosis, characterized by specific facial and limb abnormalities, of which the most frequently reported are ptosis, prominent crus helicis, cutaneous syndactyly of digit 2 and 3 on both hands and feet, and broad halluces. Saethre-Chotzen syndrome has been linked to the TWIST gene on chromosome 7p21.1. Mutations in and variably sized deletions of this gene can be found in patients with clinical features of Saethre-Chotzen syndrome. The latter, TWIST deletions, often also include part of the surrounding chromosome 7p and are reported to be associated with mental retardation. In Saethre-Chotzen patients, in whom neither a mutation nor a deletion of TWIST had been found, the FGFR3 P250R mutation was in some cases detected. This mutation has specifically been linked to Muenke syndrome that is characterized by unior bicoronal synostosis and slight facial dysmorphology. However, a Saethre-Chotzen like phenotype can also result from this mutation. Because of the possible overlap of Saethre-Chotzen with Muenke syndrome, these syndromes were studied in order to provide clinical criteria that discriminate between the two (chapter 4). Many phenotypic features occur in both syndromes. In addition, although unicoronal synostosis occurs slightly more frequently in Muenke syndrome, unicoronal and bicoronal synostosis are seen in both syndromes. The discrimination between Saethre-Chotzen and Muenke is often not made easily and the associated genes, TWIST and FGFR3, respectively, are simultaneously tested for pathogenic m

    Measurement of the Bs Lifetime in Fully and Partially Reconstructed Bs -> Ds- (phi pi-)X Decays in pbar-p Collisions at sqrt(s) = 1.96 TeV

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    We present a measurement of the Bs lifetime in fully and partially reconstructed Bs -> Ds(phi pi)X decays in 1.3 fb-1 of pbar-p collisions at sqrt(s) = 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron. We measure tau(Bs) = 1.518 +/- 0.041 (stat.) +/- 0.027 (syst.) ps. The ratio of this result and the world average B0 lifetime yields tau(Bs)/tau(B0) = 0.99 +/-0.03, which is in agreement with recent theoretical predictions.Comment: submitted to Phys. Rev. Let

    W boson polarization measurement in the ttbar dilepton channel using the CDF II Detector

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    We present a measurement of WW boson polarization in top-quark decays in ttˉt\bar{t} events with decays to dilepton final states using 5.1fb−15.1 {\rm fb^{-1}} of integrated luminosity in ppˉp\bar{p} collisions collected by the CDF II detector at the Tevatron. A simultaneous measurement of the fractions of longitudinal (f0f_0) and right-handed (f+f_+) WW bosons yields the results f0=0.71−0.17+0.18(stat)±0.06(syst)f_0 = 0.71 ^{+0.18}_{-0.17} {\rm (stat)} \pm 0.06 {\rm (syst)} and f+=−0.07±0.09(stat)±0.03(syst)f_+ = -0.07 \pm 0.09 {\rm (stat)} \pm 0.03 {\rm (syst)}. Combining this measurement with our previous result based on single lepton final states, we obtain f0=0.84±0.09(stat)±0.05(syst)f_0 = 0.84 \pm 0.09 {\rm (stat)} \pm 0.05 {\rm (syst)} and f+=−0.16±0.05(stat)±0.04(syst)f_{+} = -0.16 \pm 0.05 {\rm (stat)} \pm 0.04 {\rm (syst)}. The results are consistent with standard model expectation.Comment: Published in Phys. Lett.

    Observation of the Y(4140)Y(4140) structure in the J/ψ ϕJ/\psi\,\phi Mass Spectrum in B±→J/ψ ϕKB^\pm\to J/\psi\,\phi K cays

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    The observation of the Y(4140)Y(4140) structure in B±→J/ψ ϕK±B^\pm\rightarrow J/\psi\,\phi K^\pm decays produced in pˉp\bar{p} p collisions at \sqrt{s}=1.96~\TeV is reported with a statistical significance greater than 5 standard deviations. A fit to the J/ψ ϕJ/\psi\,\phi mass spectrum is performed assuming the presence of a Breit-Wigner resonance. The fit yields a signal of 19−5+619^{+6}_{-5} resonance events, and resonance mass and width of 4143.4^{+2.9}_{-3.0}(\mathrm{stat})\pm0.6(\mathrm{syst})~\MeVcc and 15.3^{+10.4}_{-6.1}(\mathrm{stat})\pm2.5(\mathrm{syst})~\MeVcc respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis.Comment: 7 pages, 2 figures, submited to Phys. Rev. Let

    Global burden and strength of evidence for 88 risk factors in 204 countries and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

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    Background: Understanding the health consequences associated with exposure to risk factors is necessary to inform public health policy and practice. To systematically quantify the contributions of risk factor exposures to specific health outcomes, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 aims to provide comprehensive estimates of exposure levels, relative health risks, and attributable burden of disease for 88 risk factors in 204 countries and territories and 811 subnational locations, from 1990 to 2021. Methods: The GBD 2021 risk factor analysis used data from 54 561 total distinct sources to produce epidemiological estimates for 88 risk factors and their associated health outcomes for a total of 631 risk–outcome pairs. Pairs were included on the basis of data-driven determination of a risk–outcome association. Age-sex-location-year-specific estimates were generated at global, regional, and national levels. Our approach followed the comparative risk assessment framework predicated on a causal web of hierarchically organised, potentially combinative, modifiable risks. Relative risks (RRs) of a given outcome occurring as a function of risk factor exposure were estimated separately for each risk–outcome pair, and summary exposure values (SEVs), representing risk-weighted exposure prevalence, and theoretical minimum risk exposure levels (TMRELs) were estimated for each risk factor. These estimates were used to calculate the population attributable fraction (PAF; ie, the proportional change in health risk that would occur if exposure to a risk factor were reduced to the TMREL). The product of PAFs and disease burden associated with a given outcome, measured in disability-adjusted life-years (DALYs), yielded measures of attributable burden (ie, the proportion of total disease burden attributable to a particular risk factor or combination of risk factors). Adjustments for mediation were applied to account for relationships involving risk factors that act indirectly on outcomes via intermediate risks. Attributable burden estimates were stratified by Socio-demographic Index (SDI) quintile and presented as counts, age-standardised rates, and rankings. To complement estimates of RR and attributable burden, newly developed burden of proof risk function (BPRF) methods were applied to yield supplementary, conservative interpretations of risk–outcome associations based on the consistency of underlying evidence, accounting for unexplained heterogeneity between input data from different studies. Estimates reported represent the mean value across 500 draws from the estimate's distribution, with 95% uncertainty intervals (UIs) calculated as the 2·5th and 97·5th percentile values across the draws. Findings: Among the specific risk factors analysed for this study, particulate matter air pollution was the leading contributor to the global disease burden in 2021, contributing 8·0% (95% UI 6·7–9·4) of total DALYs, followed by high systolic blood pressure (SBP; 7·8% [6·4–9·2]), smoking (5·7% [4·7–6·8]), low birthweight and short gestation (5·6% [4·8–6·3]), and high fasting plasma glucose (FPG; 5·4% [4·8–6·0]). For younger demographics (ie, those aged 0–4 years and 5–14 years), risks such as low birthweight and short gestation and unsafe water, sanitation, and handwashing (WaSH) were among the leading risk factors, while for older age groups, metabolic risks such as high SBP, high body-mass index (BMI), high FPG, and high LDL cholesterol had a greater impact. From 2000 to 2021, there was an observable shift in global health challenges, marked by a decline in the number of all-age DALYs broadly attributable to behavioural risks (decrease of 20·7% [13·9–27·7]) and environmental and occupational risks (decrease of 22·0% [15·5–28·8]), coupled with a 49·4% (42·3–56·9) increase in DALYs attributable to metabolic risks, all reflecting ageing populations and changing lifestyles on a global scale. Age-standardised global DALY rates attributable to high BMI and high FPG rose considerably (15·7% [9·9–21·7] for high BMI and 7·9% [3·3–12·9] for high FPG) over this period, with exposure to these risks increasing annually at rates of 1·8% (1·6–1·9) for high BMI and 1·3% (1·1–1·5) for high FPG. By contrast, the global risk-attributable burden and exposure to many other risk factors declined, notably for risks such as child growth failure and unsafe water source, with age-standardised attributable DALYs decreasing by 71·5% (64·4–78·8) for child growth failure and 66·3% (60·2–72·0) for unsafe water source. We separated risk factors into three groups according to trajectory over time: those with a decreasing attributable burden, due largely to declining risk exposure (eg, diet high in trans-fat and household air pollution) but also to proportionally smaller child and youth populations (eg, child and maternal malnutrition); those for which the burden increased moderately in spite of declining risk exposure, due largely to population ageing (eg, smoking); and those for which the burden increased considerably due to both increasing risk exposure and population ageing (eg, ambient particulate matter air pollution, high BMI, high FPG, and high SBP). Interpretation: Substantial progress has been made in reducing the global disease burden attributable to a range of risk factors, particularly those related to maternal and child health, WaSH, and household air pollution. Maintaining efforts to minimise the impact of these risk factors, especially in low SDI locations, is necessary to sustain progress. Successes in moderating the smoking-related burden by reducing risk exposure highlight the need to advance policies that reduce exposure to other leading risk factors such as ambient particulate matter air pollution and high SBP. Troubling increases in high FPG, high BMI, and other risk factors related to obesity and metabolic syndrome indicate an urgent need to identify and implement interventions. Funding: Bill & Melinda Gates Foundation

    Search for long-lived neutral particles in pp collisions at s√=13 TeV that decay into displaced hadronic jets in the ATLAS calorimeter

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    This paper describes a search for pairs of neutral, long-lived particles decaying in the ATLAS calorimeter. Long-lived particles occur in many extensions to the Standard Model and may elude searches for new promptly decaying particles. The analysis considers neutral, long-lived scalars with masses between 5 and 400 GeV, produced from decays of heavy bosons with masses between 125 and 1000 GeV, where the long-lived scalars decay into Standard Model fermions. The analysis uses either 10.8 fb−1 or 33.0 fb−1 of data (depending on the trigger) recorded in 2016 at the LHC with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of 13 TeV. No significant excess is observed, and limits are reported on the production cross section times branching ratio as a function of the proper decay length of the long-lived particles
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