Correlated long-range mixed-harmonic fluctuations measured in pp, p+Pb and low-multiplicity Pb+Pb collisions with the ATLAS detector

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Performance of top-quark and W -boson tagging with ATLAS in Run 2 of the LHC

The performance of identification algorithms (“taggers”) for hadronically decaying top quarks and W bosons in pp collisions at √s=13 TeV recorded by the ATLAS experiment at the Large Hadron Collider is presented. A set of techniques based on jet shape observables are studied to determine a set of optimal cut-based taggers for use in physics analyses. The studies are extended to assess the utility of combinations of substructure observables as a multivariate tagger using boosted decision trees or deep neural networks in comparison with taggers based on two-variable combinations. In addition, for highly boosted top-quark tagging, a deep neural network based on jet constituent inputs as well as a re-optimisation of the shower deconstruction technique is presented. The performance of these taggers is studied in data collected during 2015 and 2016 corresponding to 36.1 fb −1 for the tt ¯ and γ+jet and 36.7 fb −1 −1 for the dijet event topologies

In situ calibration of large-radius jet energy and mass in 13 TeV proton–proton collisions with the ATLAS detector

The response of the ATLAS detector to largeradius jets is measured in situ using 36.2 fb−1 of √s = 13 TeV proton–proton collisions provided by the LHC and recorded by the ATLAS experiment during 2015 and 2016. The jet energy scale is measured in events where the jet recoils against a reference object, which can be either a calibrated photon, a reconstructed Z boson, or a system of well-measured small-radius jets. The jet energy resolution and a calibration of forward jets are derived using dijet balance measurements. The jet mass response is measured with two methods: using mass peaks formed by W bosons and top quarks with large transverse momenta and by comparing the jet mass measured using the energy deposited in the calorimeter with that using the momenta of charged-particle tracks. The transversemomentum and mass responses in simulations are found to be about 2–3% higher than in data. This difference is adjusted for with a correction factor. The results of the different methods are combined to yield a calibration over a large range of transverse momenta (pT). The precision of the relative jet energy scale is 1–2% for 200 GeV < pT < 2 TeV, while that of the mass scale is 2–10%. The ratio of the energy resolutions in data and simulation is measured to a precision of 10–15% over the same pT range

Measurement of the photon identification efficiencies with the ATLAS detector using LHC Run 2 data collected in 2015 and 2016

The efficiency of the photon identification criteria in the ATLAS detector is measured using 36.1 fb1 to 36.7 fb1 of pp collision data at s√=13 TeV collected in 2015 and 2016. The efficiencies are measured separately for converted and unconverted isolated photons, in four different pseudorapidity regions, for transverse momenta between 10 GeV and 1.5 TeV. The results from the combination of three data-driven techniques are compared with the predictions from simulation after correcting the variables describing the shape of electromagnetic showers in simulation for the average differences observed relative to data. Data-to-simulation efficiency ratios are determined to account for the small residual efficiency differences. These factors are measured with uncertainties between 0.5% and 5% depending on the photon transverse momentum and pseudorapidity. The impact of the isolation criteria on the photon identification efficiency, and that of additional soft pp interactions, are also discussed. The probability of reconstructing an electron as a photon candidate is measured in data, and compared with the predictions from simulation. The efficiency of the reconstruction of photon conversions is measured using a sample of photon candidates from Z→μμγ events, exploiting the properties of the ratio of the energies deposited in the first and second longitudinal layers of the ATLAS electromagnetic calorimeter

Transgenic expression and activation of PGC-1\u3b1 protect dopaminergic neurons in the MPTP mouse model of Parkinson's disease

Mitochondrial dysfunction and oxidative stress occur in Parkinson\u2019s disease (PD), but little is known about the molecular mechanisms controlling these events. Peroxisome proliferator-activated receptor-gamma coactivator-1\u3b1 (PGC-1\u3b1) is a transcriptional coactivator that is a master regulator of oxidative stress and mitochondrial metabolism. We show here that transgenic mice overexpressing PGC-1\u3b1 in dopaminergic neurons are resistant against cell degeneration induced by the neurotoxin MPTP. The increase in neuronal viability was accompanied by elevated levels of mitochondrial antioxidants SOD2 and Trx2 in the substantia nigra of transgenic mice. PGC-1\u3b1 overexpression also protected against MPTP-induced striatal loss of dopamine, and mitochondria from PGC-1\u3b1 transgenic mice showed an increased respiratory control ratio compared with wild-type animals. To modulate PGC-1\u3b1, we employed the small molecular compound, resveratrol (RSV) that protected dopaminergic neurons against the MPTP-induced cell degeneration almost to the same extent as after PGC-1\u3b1 overexpression. As studied in vitro, RSV activated PGC-1\u3b1 in dopaminergic SN4741 cells via the deacetylase SIRT1, and enhanced PGC-1\u3b1 gene transcription with increases in SOD2 and Trx2. Taken together, the results reveal an important function of PGC-1\u3b1 in dopaminergic neurons to combat oxidative stress and increase neuronal viability. RSV and other compounds acting via SIRT1/PGC-1\u3b1 may prove useful as neuroprotective agents in PD and possibly in other neurological disorders

Estimating the reproducibility of psychological science

One of the central goals in any scientific endeavor is to understand causality. Experiments that seek to demonstrate a cause/effect relation most often manipulate the postulated causal factor. Aarts et al. describe the replication of 100 experiments reported in papers published in 2008 in three high-ranking psychology journals. Assessing whether the replication and the original experiment yielded the same result according to several criteria, they find that about one-third to one-half of the original findings were also observed in the replication study

Prospective multicenter study of HX575 (biosimilar epoetin-\u3b1) in patients with chronic kidney disease applying a target hemoglobin of 10--12 g/dl

HX575 was approved in the European Union in August 2007 as the first-ever biosimilar epoetin-\u3b1 product. The present study extended the safety database on HX575 by monitoring adverse events (AEs) in clinical practice. Hemoglobin (Hb) levels and HX575 doses were recorded for the assessment of efficacy. This open, 6-month single-arm study was conducted in 10 European countries with a target enrollment of 1,500 patients with anemia due to chronic kidney disease (CKD). HX575 was intravenously (i.v.) administered aiming at an Hb target of 10 - 12 g/dl. Most patients (92.3%) had already received erythropoiesis stimulating agents (ESAs) treatment before enrolment into this study; the recorded treatments mainly comprised i.v. or subcutaneous (s.c.) administration of epoetin-\u3b1, epoetin-\u3b2 or darbepoetin. The study period covered 770 patient years. The observed AE profile was in line with expectations for this patient population. Thrombotic vascular events (TVEs) were reported in 11.9% of patients (0.2612 per patient year). Tumor incidence was 1.4% (0.0299 per patient year). No subject developed anti-epoetin antibodies. Mean Hb levels were effectively maintained between 11.2 and 11.3 g/dl following the conversion from a broad spectrum of pre-study ESA treatments with stable overall mean i.v. HX575 doses. The proportion of patients within the Hb target range increased from 57.5% at baseline to 66.8% at study end

Observation of Light-by-Light Scattering in Ultraperipheral Pb plus Pb Collisions with the ATLAS Detector

This letter describes the observation of the light-by-light scattering process, $\gamma\gamma\rightarrow\gamma\gamma$, in Pb+Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb$^{-1}$, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy $E_{\textrm{T}}^{\gamma} > 3$ GeV and pseudorapidity $|\eta_{\gamma}| < 2.37$, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12 $\pm$ 3 events. The observed excess of events over the expected background has a significance of 8.2 standard deviations. The measured fiducial cross section is 78 $\pm$ 13 (stat.) $\pm$ 7 (syst.) $\pm$ 3 (lumi.) nb.Comment: 29 pages in total, author list starting page 13, 2 figures, 0 tables, final version published in PRL. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2018-1

ATLAS Collaboration

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