471 research outputs found

    Multi-particle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider

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    Measurements of multi-particle azimuthal correlations (cumulants) for charged particles in p-Pb and Pb-Pb collisions are presented. They help address the question of whether there is evidence for global, flow-like, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a Δη|\Delta \eta| gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high-multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of v2{4}v_{2}\{4\} to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find v2{4}v2{6}0v_{2}\{4\} \simeq v_{2}\{6\}\neq 0 which is indicative of a Bessel-Gaussian function for the v2v_{2} distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a Δη>1.4|\Delta\eta| > 1.4 gap is placed.Comment: 25 pages, 11 captioned figures, 3 tables, authors from page 20, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/87

    Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

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    Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 <pT,assoc<pT,trig< < p_{\rm{T}, assoc} < p_{\rm{T}, trig} < 5.0 GeV/cc is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range η<0.9|\eta|<0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

    ϕ-Meson production at forward rapidity in p–Pb collisions at √sNN = 5.02 TeV and in pp collisions at √s = 2.76 TeV

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    The first measurement of phiphi-meson production in p-Pb collisions at a nucleon-nucleon centre-of-mass energy sqrtsrmNNsqrt{s_{rm NN}} = 5.02 TeV has been performed with the ALICE apparatus at the LHC. The phiphi-mesons have been identified in the dimuon decay channel in the transverse momentum (prmTp_{rm T}) range 1<prmT<71 < p_{rm T} < 7 GeV/cc, both in the p-going (2.03<y<3.532.03 < y < 3.53) and the Pb-going (4.46<y<2.96-4.46 < y < -2.96) directions, where yy stands for the rapidity in the nucleon-nucleon centre-of-mass. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward-backward asymmetry for phiphi-meson production is measured for 2.96<y<3.532.96< y <3.53, resulting in a factor sim0.5sim 0.5 with no significant prmTp_{rm T} dependence within the uncertainties. The prmTp_{rm T} dependence of the phiphi nuclear modification factor RrmpPbR_{rm pPb} exhibits an enhancement up to a factor 1.6 at prmTp_{rm T} = 3-4 GeV/cc in the Pb-going direction. The prmTp_{rm T} dependence of the phiphi-meson cross section in pp collisions at sqrtssqrt{s} = 2.76 TeV, which is used to determine a reference for the p-Pb results, is also presented here for 1<prmT<51 < p_{rm T} < 5 GeV/cc and 2.5<y<42.5 <y < 4

    Impact of the Covid-19 pandemic on perinatal mental health (Riseup-PPD-COVID-19): protocol for an international prospective cohort study

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    Background: Corona Virus Disease 19 (COVID-19) is a new pandemic, declared a public health emergency by the World Health Organization, which could have negative consequences for pregnant and postpartum women. The scarce evidence published to date suggests that perinatal mental health has deteriorated since the COVID-19 outbreak. However, the few studies published so far have some limitations, such as a cross-sectional design and the omission of important factors for the understanding of perinatal mental health, including governmental restriction measures and healthcare practices implemented at the maternity hospitals. Within the Riseup-PPD COST Action, a study is underway to assess the impact of COVID-19 in perinatal mental health. The primary objectives are to (1) evaluate changes in perinatal mental health outcomes; and (2) determine the risk and protective factors for perinatal mental health during the COVID-19 pandemic. Additionally, we will compare the results between the countries participating in the study. Methods: This is an international prospective cohort study, with a baseline and three follow-up assessments over a six-month period. It is being carried out in 11 European countries (Albania, Bulgaria, Cyprus, France, Greece, Israel, Malta, Portugal, Spain, Turkey, and the United Kingdom), Argentina, Brazil and Chile. The sample consists of adult pregnant and postpartum women (with infants up to 6 months of age). The assessment includes measures on COVID-19 epidemiology and public health measures (Oxford COVID-19 Government Response Tracker dataset), Coronavirus Perinatal Experiences (COPE questionnaires), psychological distress (BSI-18), depression (EPDS), anxiety (GAD-7) and post-traumatic stress symptoms (PTSD checklist for DSM-V). Discussion: This study will provide important information for understanding the impact of the COVID-19 pandemic on perinatal mental health and well-being, including the identification of potential risk and protective factors by implementing predictive models using machine learning techniques. The findings will help policymakers develop suitable guidelines and prevention strategies for perinatal mental health and contribute to designing tailored mental health interventions. Trial registration: ClinicalTrials.gov Identifier: NCT04595123.The project is part of the COST Action Riseup-PPD CA 18138 and was supported by COST under COST Action Riseup-PPD CA18138; also, by the Spanish Ministry of Health, the Institute of Health Carlos III, and the European Regional Development Fund «Una manera de hacer Europa» by the Prevention and Health Promotion Research Network ‘redIAPP’ (RD16/0007). Raquel Costa is supported by the FSE and FCT under an individual Post-Doctoral Grant SFRH/BPD/117597/2016. Rena Bina and Drorit Levy received funding from the Bar-Ilan Dangoor Centre for Personalized Medicine, Israel. Ana Mesquita is supported from the Portuguese Foundation for Science and Technology (FCT) and from EU through the European Social Fund and from the Human Potential Operational Program - IF/00750/2015. Ana Osório received financial support from CAPES/Proex no. 0653/2018 and CAPES/PrInt grant no. 88887.310343/2018-00.The funders of the study had no role in the study design or the writing the protocol. The corresponding author had final responsibility for the decision to submit for publication

    Regional mitochondrial DNA and cell-type changes in post-mortem brains of non-diabetic Alzheimer’s disease are not present in diabetic Alzheimer’s disease

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    Background: Mitochondrial dysfunction is implicated in both diabetes and Alzheimer’s disease (AD), and diabetes also increases the risk of AD, however the combined impact of AD and diabetes on brain mitochondria is unknown. The purpose of this study was to test the hypothesis that the combination of both diabetes and AD exacerbates mitochondrial dysfunction. Methods: Post-mortem human brains (n=74), were used to determine mitochondrial DNA (mtDNA) content of cerebellum, frontal cortex and parietal cortex by quantifying absolute mtDNA copy number/cell using real time qPCR. mtDNA content was compared between diabetic and non-diabetic cases representing non-cognitively impaired controls (NCI), mildly cognitively impaired (MCI) and AD. A subset of parietal cortex samples was used to quantify mRNAs corresponding to cell types and mitochondrial function. Immune-staining of parietal cortex sections followed by semi-automated stereological assessment was performed to assess cell types. Results. Using mtDNA as an indicator of mitochondrial content, we observed significant regional variation, being highest in the parietal cortex, and lowest in the cerebellum. In the absence of diabetes, AD cases had decreased parietal cortex mtDNA, reduced MAP2 (neuronal) mRNA and increased GFAP (astrocyte) mRNA, relative to NCI. However, in the presence of both diabetes and AD, we did not observe these changes in the parietal cortex. Irrespective of cognitive status, all 3 brain regions in diabetic cases had significantly higher mtDNA than the non-diabetic cases. Conclusion. Our data show that the parietal cortex has the highest mitochondrial content but is also the most vulnerable to changes in AD, as shown by reduced mtDNA and neurones in this region. In contrast, when patients have both diabetes and AD, the AD associated parietal cortex changes are no longer seen, suggesting that the pathology observed in diabetic AD may be different to that seen in non-diabetic AD. The lack of clear functional changes in mitochondrial parameters in diabetic AD suggest that there may be different mechanisms contributing to cognitive impairment in diabetes and their impact on the respective disease neuro-pathologies remain to be fully understood

    Learning with a network of competing synapses

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    Competition between synapses arises in some forms of correlation-based plasticity. Here we propose a game theory-inspired model of synaptic interactions whose dynamics is driven by competition between synapses in their weak and strong states, which are characterized by different timescales. The learning of inputs and memory are meaningfully definable in an effective description of networked synaptic populations. We study, numerically and analytically, the dynamic responses of the effective system to various signal types, particularly with reference to an existing empirical motor adaptation model. The dependence of the system-level behavior on the synaptic parameters, and the signal strength, is brought out in a clear manner, thus illuminating issues such as those of optimal performance, and the functional role of multiple timescales.Comment: 16 pages, 9 figures; published in PLoS ON

    Measurements of π± differential yields from the surface of the T2K replica target for incoming 31 GeV/c protons with the NA61/SHINE spectrometer at the CERN SPS

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    Measurements of particle emission from a replica of the T2K 90 cm-long carbon target were performed in the NA61/SHINE experiment at CERN SPS, using data collected during a high-statistics run in 2009. An efficient use of the long-target measurements for neutrino flux predictions in T2K requires dedicated reconstruction and analysis techniques. Fully-corrected differential yields of π ± -mesons from the surface of the T2K replica target for incoming 31 GeV/c protons are presented. A possible strategy to implement these results into the T2K neutrino beam predictions is discussed and the propagation of the uncertainties of these results to the final neutrino flux is performed

    K0S and Λ production in Pb-Pb collisions at sNN−−−−√=2.76  TeV

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    The ALICE measurement of K0S and Λ production at midrapidity in Pb-Pb collisions at sNN−−−√=2.76  TeV is presented. The transverse momentum (pT) spectra are shown for several collision centrality intervals and in the pT range from 0.4  GeV/c (0.6  GeV/c for Λ) to 12  GeV/c. The pT dependence of the Λ/K0S ratios exhibits maxima in the vicinity of 3  GeV/c, and the positions of the maxima shift towards higher pT with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate pT is not observed in pp interactions at s√=0.9  TeV and at s√=7  TeV. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured pT spectra above 2  GeV/c progressively decouple from hydrodynamical-model calculations. For higher values of pT, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the pT dependence of the Λ/K0S ratio

    Addendum: Centrality dependence of high-p(T) D-meson suppression in Pb-Pb collisions at root s(NN) = 2.7 6 TeV

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    Sem informaçãoThis is an addendum to the article JHEP 11 (2015) 205 [1]. The figures 3 (right), 4 (right) and 5 are updated with published results on non-prompt J/psi-meson production from the CMS collaboration [2].6111Sem informaçãoSem informaçãoSem informaçã
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