321 research outputs found
Spin alignment measurements using vector mesons with ALICE detector at the LHC
We present new measurements related to spin alignment of K*(0) vector
mesons at mid-rapidity for Pb-Pb collisions at root s(NN) = 2.76 and
5.02 TeV. The spin alignment measurements are carried out with respect
to production plane and 2nd order event plane. At low p(T) the spin
density matrix element rho(00) for K*(0) is found to have values
slightly below 1/3, while it is consistent with 1/3, i.e. no spin
alignment, at high p(T). Similar values of rho(00) are observed with
respect to both production plane and event plane. Within statistical and
systematic uncertainties, rho(00) values are also found to be
independent of root s(NN). rho(00) also shows centrality dependence with
maximum deviation from 1/3 for mid-central collisions with respect to
both the kinematic planes. The measurements for K*(0) in pp collisions
at root s = 13 TeV and for K-s(0) (a spin 0 hadron) in 20-40\% central
Pb-Pb collisions at root s(NN) = 2.76 TeV are consistent with no spin
alignment
Muon physics at forward rapidity with the ALICE detector upgrade
ALICE is the experiment specifically designed to study the Quark-Gluon
Plasma (QGP) in heavy-ion collisions at the CERN LHC. The ALICE detector
will be upgraded during the Long Shutdown 2, planned for 2019-2020, in
order to cope with the maximum interaction rate of 50 kHz of Pb-Pb
collisions foreseen for Runs 3 and 4. The ambitious programme of
high-precision measurements, expected for muon physics after 2020,
requires an upgrade of the front-end and readout electronics of the
existing Muon Spectrometer. This concerns the Cathode Pad Chambers (CPC)
used for tracking and the Resistive Plate Chambers (RPC) used for
triggering and for muon identification. The Muon Forward Tracker (MFT),
an internal tracker added in front of the front absorber of the existing
Muon Spectrometer, is also part of the ALICE detector upgrade programme.
It is based on an assembly of circular planes made of Monolithic Active
Pixel Sensors (MAPS), covering the pseudorapidity range 2.5 < eta < 3.6.
The MFT will improve present measurements and enable new ones. A
selection of results from physics performance studies will be presented,
together with an overview of the technical aspects of the upgrade
project
Higher moment fluctuations of identified particle distributions from ALICE
Cumulants of conserved charges fluctuations are regarded as a potential tool
to study the criticality in the QCD phase diagram and to determine the
freeze-out parameters in a model-independent way. At LHC energies, the
measurements of the ratio of the net-baryon (net-proton) cumulants can be used
to test the lattice QCD predictions. In this work, we present the first
measurements of cumulants of the net-proton number distributions up to
order in Pb--Pb collisions at = 2.76 and 5.02 TeV as a
function of collision centrality. We compare our cumulant ratios results with
the STAR experiment net-proton results measured in the first phase of the Beam
Energy Scan program at RHIC. The results can be used to obtain the chemical
freeze-out parameters at LHC.Comment: 4 pages, 3 figures, Proceedings of XXVIIth International Conference
on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018
Direct photon elliptic flow in Pb-Pb collisions at root s(NN)=2.76 TeV
The elliptic flow of inclusive and direct photons was measured at mid-rapidity in two centrality classes 0-20% and 20-40% in Pb-Pb collisions at root s(NN) = 2.76 TeV by ALICE. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the detector material with the e(broken vertical bar)e pairs reconstructed in the central tracking system. The results of the two methods were combined and the direct-photon elliptic flow was extracted in the transverse momentum range 0.9 < p(T) < 6.2 GeV/c. A comparison to RHIC data shows a similar magnitude of the measured direct-photon elliptic flow. Hydrodynamic and transport model calculations are systematically lower than the data, but are found to be compatible. (C) 2018 The Author. Published by Elsevier B.V.Peer reviewe
Measuring (KSK +/-)-K-0 interactions using pp collisions at root s=7 TeV
We present the first measurements of femtoscopic correlations between the K-S(0) and K-+/- particles in pp collisions at root s = 7 TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding solely via the a(0)(980) resonance. The extracted kaon source radius and correlation strength parameters for (KSK-)-K-0 are found to be equal within the experimental uncertainties to those for (KSK+)-K-0. Results of the present study are compared with those from identical-kaon femtoscopic studies also performed with pp collisions at root s = 7 TeV by ALICE and with a (KSK +/-)-K-0 measurement in Pb-Pb collisions at root s(NN) = 2.76 TeV. Combined with the Pb-Pb results, our pp analysis is found to be compatible with the interpretation of the a (980) having a tetraquark structure instead of that of a diquark. (C) 2018 Published by Elsevier B.V.Peer reviewe
Light (anti-)nuclei production and elliptic flow at the LHC with ALICE
Results on the production of stable light nuclei, including deuterons,
He-3, He-4 and the corresponding anti-nuclei, in Pb-Pb collisions at
root s(NN) = 2.76 TeV and root s(NN) = 5.02 TeV are presented and
compared with theoretical predictions and with the results in small
systems to provide insight into the production mechanisms of
(anti-)nuclei at colliders.
The experimental results are presented giving a critical view of their
comparison to the expectations from coalescence and hydrodynamic models
that aim at describing both the p(T)-spectra and the elliptic flow
Open heavy-flavour production and elliptic flow in p-Pb collisions at the LHC with ALICE
Measurements of open heavy flavour production in p-A collisions allow
the investigation of Cold Nuclear Matter effects. In addition, they are
an important tool for a complementary investigation of the long-range
correlations found in small systems in the light flavour sector. In this
work, production measurements of D mesons at mid-rapidity in p-Pb
collisions at root S-NN = 5.02 TeV are reported. Production yields are
also reported for the heavy-flavour hadron decay electrons at central
rapidity at root(SNN) = 5.02 and 8.16 TeV. The elliptic flow (nu(2)) of
heavy-flavour hadron decay electrons in high multiplicity p-Pb
collisions at root(SNN) = 5.02 TeV is found to be positive with a
significance larger than 5 sigma
Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study
Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research
Measuring performance on the Healthcare Access and Quality Index for 195 countries and territories and selected subnational locations: A systematic analysis from the Global Burden of Disease Study 2016
Background A key component of achieving universal health coverage is ensuring that all populations have access to
quality health care. Examining where gains have occurred or progress has faltered across and within countries is
crucial to guiding decisions and strategies for future improvement. We used the Global Burden of Diseases, Injuries,
and Risk Factors Study 2016 (GBD 2016) to assess personal health-care access and quality with the Healthcare Access
and Quality (HAQ) Index for 195 countries and territories, as well as subnational locations in seven countries, from
1990 to 2016.
Methods Drawing from established methods and updated estimates from GBD 2016, we used 32 causes from which
death should not occur in the presence of effective care to approximate personal health-care access and quality by
location and over time. To better isolate potential effects of personal health-care access and quality from underlying
risk factor patterns, we risk-standardised cause-specific deaths due to non-cancers by location-year, replacing the local
joint exposure of environmental and behavioural risks with the global level of exposure. Supported by the expansion
of cancer registry data in GBD 2016, we used mortality-to-incidence ratios for cancers instead of risk-standardised
death rates to provide a stronger signal of the effects of personal health care and access on cancer survival. We
transformed each cause to a scale of 0–100, with 0 as the first percentile (worst) observed between 1990 and 2016, and
100 as the 99th percentile (best); we set these thresholds at the country level, and then applied them to subnational
locations. We applied a principal components analysis to construct the HAQ Index using all scaled cause values,
providing an overall score of 0–100 of personal health-care access and quality by location over time. We then compared
HAQ Index levels and trends by quintiles on the Socio-demographic Index (SDI), a summary measure of overall
development. As derived from the broader GBD study and other data sources, we examined relationships between
national HAQ Index scores and potential correlates of performance, such as total health spending per capita.
Findings In 2016, HAQ Index performance spanned from a high of 97·1 (95% UI 95·8–98·1) in Iceland, followed by
96·6 (94·9–97·9) in Norway and 96·1 (94·5–97·3) in the Netherlands, to values as low as 18·6 (13·1–24·4) in
the Central African Republic, 19·0 (14·3–23·7) in Somalia, and 23·4 (20·2–26·8) in Guinea-Bissau. The pace of
progress achieved between 1990 and 2016 varied, with markedly faster improvements occurring between 2000 and
2016 for many countries in sub-Saharan Africa and southeast Asia, whereas several countries in Latin America and
elsewhere saw progress stagnate after experiencing considerable advances in the HAQ Index between 1990 and 2000.
Striking subnational disparities emerged in personal health-care access and quality, with China and India having
particularly large gaps between locations with the highest and lowest scores in 2016. In China, performance ranged
from 91·5 (89·1–93·6) in Beijing to 48·0 (43·4–53·2) in Tibet (a 43·5-point difference), while India saw a 30·8-point
disparity, from 64·8 (59·6–68·8) in Goa to 34·0 (30·3–38·1) in Assam. Japan recorded the smallest range in
subnational HAQ performance in 2016 (a 4·8-point difference), whereas differences between subnational locations
with the highest and lowest HAQ Index values were more than two times as high for the USA and three times as high
for England. State-level gaps in the HAQ Index in Mexico somewhat narrowed from 1990 to 2016 (from a 20·9-point
to 17·0-point difference), whereas in Brazil, disparities slightly increased across states during this time (a 17·2-point
to 20·4-point difference). Performance on the HAQ Index showed strong linkages to overall development, with high
and high-middle SDI countries generally having higher scores and faster gains for non-communicable diseases.
Nonetheless, countries across the development spectrum saw substantial gains in some key health service areas from
2000 to 2016, most notably vaccine-preventable diseases. Overall, national performance on the HAQ Index was
positively associated with higher levels of total health spending per capita, as well as health systems inputs, but these
relationships were quite heterogeneous, particularly among low-to-middle SDI countries.
Interpretation GBD 2016 provides a more detailed understanding of past success and current challenges in improving
personal health-care access and quality worldwide. Despite substantial gains since 2000, many low-SDI and middle-
SDI countries face considerable challenges unless heightened policy action and investments focus on advancing access to and quality of health care across key health services, especially non-communicable diseases. Stagnating or
minimal improvements experienced by several low-middle to high-middle SDI countries could reflect the complexities
of re-orienting both primary and secondary health-care services beyond the more limited foci of the Millennium
Development Goals. Alongside initiatives to strengthen public health programmes, the pursuit of universal health
coverage hinges upon improving both access and quality worldwide, and thus requires adopting a more comprehensive
view—and subsequent provision—of quality health care for all populations.info:eu-repo/semantics/publishedVersio
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Development of design and simulation model and safety study of large-scale hydrogen production using nuclear power.
Before this LDRD research, no single tool could simulate a very high temperature reactor (VHTR) that is coupled to a secondary system and the sulfur iodine (SI) thermochemistry. Furthermore, the SI chemistry could only be modeled in steady state, typically via flow sheets. Additionally, the MELCOR nuclear reactor analysis code was suitable only for the modeling of light water reactors, not gas-cooled reactors. We extended MELCOR in order to address the above deficiencies. In particular, we developed three VHTR input models, added generalized, modular secondary system components, developed reactor point kinetics, included transient thermochemistry for the most important cycles [SI and the Westinghouse hybrid sulfur], and developed an interactive graphical user interface for full plant visualization. The new tool is called MELCOR-H2, and it allows users to maximize hydrogen and electrical production, as well as enhance overall plant safety. We conducted validation and verification studies on the key models, and showed that the MELCOR-H2 results typically compared to within less than 5% from experimental data, code-to-code comparisons, and/or analytical solutions
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