1,518 research outputs found
MCSTHAR++, a Monte Carlo code for the microcanonical hadronization
MCSTHAR++ is a new Monte Carlo code implementing the Statistical
Hadronization Model. This model assumes that hadronization proceeds through the
microcanonical decay of massive extended clusters. Unlike other hadronization
models, in this approach very few free parameters are needed, as has been
demonstrated in previous studies. The tuning of the model and the comparison
with the data is ongoing.Comment: 3 pages; To appear in the proceedings of the conference IFAE 2010,
Roma, Italy, 7-9 April 201
A Monte-Carlo generator for statistical hadronization in high energy e+e- collisions
We present a Monte-Carlo implementation of the Statistical Hadronization
Model in e+e- collisions. The physical scheme is based on the statistical
hadronization of massive clusters produced by the event generator Herwig within
the microcanonical ensemble. We present a preliminary comparison of several
observables with measurements in e+e- collisions at the Z peak. Although a fine
tuning of the model parameters is not carried out, a general good agreement
between its predictions and data is found.Comment: 19 pages, 28 figures, 6 tables. v2: added sections on comparison
between the Statistical Hadronization Model and the Cluster Model and on the
interplay between Herwig cluster splitting algorithm and Statistical
Hadronization Model predictions. Fixed typos and references added. Version
accepted for publication in EPJ
Strangeness counting in high energy collisions
The estimates of overall strange quark production in high energy e+e-, pp and
ppbar collisions by using the statistical-thermal model of hadronisation are
presented and compared with previous works. The parametrization of strangeness
suppression within the model is discussed. Interesting regularities emerge in
the strange/non-strange produced quark ratio which turns out to be fairly
constant in elementary collisions while it is twice as large in SPS heavy ion
collision.Comment: talk given at Strangeness in Quark Matter 98, submitted to J. Phys.
System Size Dependence of Particle Production at the SPS
Recent results on the system size dependence of net-baryon and hyperon
production as measured at the CERN SPS are discussed. The observed Npart
dependences of yields, but also of dynamical properties, such as average
transverse momenta, can be described in the context of the core corona
approach. Other observables, such as antiproton yields and net-protons at
forward rapidities, do not follow the predictions of this model. Possible
implications for a search for a critical point in the QCD phase diagram are
discussed. Event-by-event fluctuations of the relative core to corona source
contributions might influence fluctuation observables (e.g. multiplicity
fluctuations). The magnitude of this effect is investigated.Comment: 10 pages, 4 figurs. Proceedings of the 6th International Workshop on
Critical Point and Onset of Deconfinement in Dubna, Aug. 201
Possible Resolutions of the D-Paradox
We propose possible ways of explaining the net charge event-by-event
fluctuations in Au+Au collisions at the Relativistic Heavy Ion Collider within
a quark recombination model. We discuss various methods of estimating the
number of quarks at recombination and their implications for the predicted net
charge fluctuations. We also discuss the possibility of diquark and
quark-antiquark clustering above the deconfinement temperature.Comment: 5 pages, 2 figure
Role of heparin prophylaxis at different doses in patients with COVID-19 and respiratory failure: a systematic review and meta-analysis
Abstract
Background
Venous thromboembolism (VTE) is common in patients with coronavirus disease-2019 (COVID-19). The use of heparin at higher doses than prophylactic is advocated, but the optimal regimens remain unknown due to the balance between prevention of thromboembolic events and bleeding risks.
Objective
To systematically review and perform a meta-analysis aimed at evaluating the risk of VTE and of major bleeding (MB) in patients with respiratory failure due to COVID-19 according to heparin doses.
Methods
We performed a systematic search in MEDLINE up until 22 March 2021. Studies on patients with respiratory failure due to COVID-19 were included if reported on study outcomes according to standard prophylactic and to higher heparin doses and included more than 10 patients. Study primary outcome was VTE; secondary outcomes were MB, all-cause death, fatal bleeding and fatal pulmonary embolism (PE).
Results
Overall, 2 randomized and 16 observational studies were selected (3458 patients). In 13 studies (2492 patients) VTE events were similar in patients receiving standard prophylaxis or higher heparin doses (RR 1.06, 95% CI 0.58–1.95, I2 87%; only randomized studies RR 1.72, 95% CI 0.78–3.81, I2 54%). 16 studies (3174) reporting on MB and showed a significant reduction in favor of standard heparin prophylaxis (RR 0.39, 95% CI 0.28–0.53, I2 8%). No differences were observed for overall mortality according to heparin doses (RR 1.11, 95% CI 0.88–1.40, I2 68%; in 8 studies, 2448 patients). Similarly, no differences were observed for fatal bleedings and fatal PEs.
In the subanalysis of studies reporting only on intensive care unit patients (ICU) an increase in the risk of VTE (RR 1.86, 95% CI 1.28–2.72, I2 18%) and a reduction on the risk of MB (RR 0.60, 95% CI 0.40–0.90, I2 0%) were observed in patients receiving standard heparin doses compared to higher doses. Overall mortality was similar (RR 1.09, 95% CI 0.86–1.39, I2 64%).
Conclusion
Different doses of heparin prophylaxis seem to not affect the risk of VTE in the overall patients with COVID-19 and respiratory failure. In studies reporting only on ICU patients the risk of VTE was lower when higher heparin doses were used compared to standard doses, but with no advantage in overall death and with an increase of MBs.
Funding Acknowledgement
Type of funding sources: None
The QCD confinement transition: hadron formation
We review the foundations and the applications of the statistical and the
quark recombination model as hadronization models.Comment: 45 pages, 16 figures, accepted for publication in Landolt-Boernstein
Volume 1-23
The canonical partition function for relativistic hadron gases
Particle production in high-energy collisions is often addressed within the
framework of the thermal (statistical) model. We present a method to calculate
the canonical partition function for the hadron resonance gas with exact
conservation of the baryon number, strangeness, electric charge, charmness and
bottomness. We derive an analytical expression for the partition function which
is represented as series of Bessel functions. Our results can be used directly
to analyze particle production yields in elementary and in heavy ion
collisions. We also quantify the importance of quantum statistics in the
calculations of the light particle multiplicities in the canonical thermal
model of the hadron resonance gas.Comment: 10 pages, 2 figures; submitted for publication in EPJ
Multiplicity Distributions in Canonical and Microcanonical Statistical Ensembles
The aim of this paper is to introduce a new technique for calculation of
observables, in particular multiplicity distributions, in various statistical
ensembles at finite volume. The method is based on Fourier analysis of the
grand canonical partition function. Taylor expansion of the generating function
is used to separate contributions to the partition function in their power in
volume. We employ Laplace's asymptotic expansion to show that any equilibrium
distribution of multiplicity, charge, energy, etc. tends to a multivariate
normal distribution in the thermodynamic limit. Gram-Charlier expansion allows
additionally for calculation of finite volume corrections. Analytical formulas
are presented for inclusion of resonance decay and finite acceptance effects
directly into the system partition function. This paper consolidates and
extends previously published results of current investigation into properties
of statistical ensembles.Comment: 53 pages, 7 figure
Unified Description of Freeze-Out Parameters in Relativistic Heavy Ion Collisions
It is shown that the chemical freeze-out parameters obtained at CERN/SPS,
BNL/AGS and GSI/SIS energies all correspond to a unique value of 1 GeV per
hadron in the local rest frame of the system, independent of the beam energy
and of the target and beam particles.Comment: revtex, 1 figur
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