1,090 research outputs found
Event-by-Event Fluctuations of Particle Ratios in Heavy-Ion Collisions
We study event-by-event dynamical fluctuations of various particle ratios at
different energies. We assume that particle production in final state is due to
chemical equilibrium processes. We compare results from resonance gas model
with available experimental data. At SPS energies, the model can very well
reproduce the experimentally measured fluctuations. We make predictions for
dynamical fluctuations of strangeness and non-strangeness particle ratios. We
found that the energy-dependence is non-monotonic. Furthermore, we found that
fluctuations strongly depend on particle ratios.Comment: 6 pages, 2 figure, 1 tabl
QCD thermodynamics and magnetization in nonzero magnetic field
In nonzero magnetic field, the magnetic properties and thermodynamics of the
quantum-chromodynamic (QCD) matter is studied in the hadron resonance gas and
the Polyakov linear-sigma models and compared with recent lattice calculations.
Both models are fairly suited to describe the degrees of freedom in the
hadronic phase. The partonic ones are only accessible by the second model. It
is found that the QCD matter has paramagnetic properties, which monotonically
depend on the temperature and are not affected by the hadron-quark
phase-transition. Furthermore, raising the magnetic field strength increases
the thermodynamic quantities, especially in the hadronic phase but reduces the
critical temperature, i.e. inverse magnetic catalysis.Comment: 14 pages, 3 figures accepted for publication in AHE
On dynamical net-charge fluctuations within a hadron resonance gas approach
The dynamical net-charge fluctuations () in different particle
ratios , , and are calculated from the hadron resonance
gas (HRG) model and compared with STAR central Au+Au collisions at
GeV and NA49 central Pb+Pb collisions at
GeV. The three charged-particle ratios (,
, and ) are determined as total and average of opposite and
average of same charges. We find an excellent agreement between the HRG
calculations and the experimental measurements, especially from STAR beam
energy scan (BES) program, while the strange particles in the NA49 experiment
at lower Super Proton Synchrotron (SPS) energies are not reproduced by the HRG
approach. We conclude that the utilized HRG version seems to take into
consideration various types of correlations including strong interactions
through the heavy resonances and their decays especially at BES energies.Comment: 8 pages, 1 figure, accepted for publication in Advances in High
Energy Physic
Nurse telephone triage for same day appointments in general practice: multiple interrupted time series trial of effect on workload and costs
OBJECTIVE: To compare the workloads of general practitioners and nurses and costs of patient care for nurse telephone triage and standard management of requests for same day appointments in routine primary care. DESIGN: Multiple interrupted time series using sequential introduction of experimental triage system in different sites with repeated measures taken one week in every month for 12 months. SETTING: Three primary care sites in York. Participants: 4685 patients: 1233 in standard management, 3452 in the triage system. All patients requesting same day appointments during study weeks were included in the trial. MAIN OUTCOME MEASURES: Type of consultation (telephone, appointment, or visit), time taken for consultation, presenting complaints, use of services during the month after same day contact, and costs of drugs and same day, follow up, and emergency care. RESULTS: The triage system reduced appointments with general practitioner by 29-44%. Compared with standard management, the triage system had a relative risk (95% confidence interval) of 0.85 (0.72 to 1.00) for home visits, 2.41 (2.08 to 2.80) for telephone care, and 3.79 (3.21 to 4.48) for nurse care. Mean overall time in the triage system was 1.70 minutes longer, but mean general practitioner time was reduced by 2.45 minutes. Routine appointments and nursing time increased, as did out of hours and accident and emergency attendance. Costs did not differ significantly between standard management and triage: mean difference £1.48 more per patient for triage (95% confidence interval -0.19 to 3.15). CONCLUSIONS: Triage reduced the number of same day appointments with general practitioners but resulted in busier routine surgeries, increased nursing time, and a small but significant increase in out of hours and accident and emergency attendance. Consequently, triage does not reduce overall costs per patient for managing same day appointments
Matter-Antimatter Asymmetry in the Large Hadron Collider
The matter-antimatter asymmetry is one of the greatest challenges in the
modern physics. The universe including this paper and even the reader
him(her)self seems to be built up of ordinary matter only. Theoretically, the
well-known Sakharov's conditions remain the solid framework explaining the
circumstances that matter became dominant against the antimatter while the
universe cools down and/or expands. On the other hand, the standard model for
elementary particles apparently prevents at least two conditions out of them.
In this work, we introduce a systematic study of the antiparticle-to-particle
ratios measured in various and collisions over the last three
decades. It is obvious that the available experimental facilities turn to be
able to perform nuclear collisions, in which the matter-antimatter asymmetry
raises from at AGS to at LHC. Assuming that the final
state of hadronization in the nuclear collisions takes place along the
freezeout line, which is defined by a constant entropy density, various
antiparticle-to-particle ratios are studied in framework of the hadron
resonance gas (HRG) model. Implementing modified phase space and distribution
function in the grand-canonical ensemble and taking into account the
experimental acceptance, the ratios of antiparticle-to-particle over the whole
range of center-of-mass-energies are very well reproduced by the HRG model.
Furthermore, the antiproton-to-proton ratios measured by ALICE in
collisions is also very well described by the HRG model. It is likely to
conclude that the LHC heavy-ion program will produce the same particle ratios
as the program implying the dynamics and evolution of the system would not
depend on the initial conditions. The ratios of bosons and baryons get very
close to unity indicating that the matter-antimatter asymmetry nearly vanishes
at LHC.Comment: 9 pages, 5 eps-figures, revtex4-styl
Particle production and chemical freezeout from the hybrid UrQMD approach at NICA energies
The energy dependence of various particle ratios is calculated within the
Ultra-Relativistic Quantum Molecular Dynamics approach and compared with the
hadron resonance gas (HRG) model and measurements from various experiments,
including RHIC-BES, SPS and AGS. It is found that the UrQMD particle ratios
agree well with the experimental results at the RHIC-BES energies. Thus, we
have utilized UrQMD in simulating particle ratios at other beam energies down
to 3 GeV, which will be accessed at NICA and FAIR future facilities. We observe
that the particle ratios for crossover and first-order phase transition,
implemented in the hybrid UrQMD v3.4, are nearly indistinguishable, especially
at low energies (at large baryon chemical potentials or high density).Comment: 13 pages, 5 figures, 2 tables, one reference is added and one
paragraph is rephrased. To appear in EPJ
Fluctuations of Particle Yield Ratios in Heavy-Ion Collisions
We study the dynamical fluctuations of various particle yield ratios at
different incident energies. Assuming that the particle production yields in
the hydronic final state are due to equilibrium chemical processes
(), the experimental results available so far are compared with the
hadron resonance gas model (HRG) taking into account the limited momentum
acceptance in heavy-ion collisions experiments. Degenerated light and conserved
strange quarks are presumed at all incident energies. At the SPS energies, the
HRG with provides a good description for the measured dynamical
fluctuations in . To reproduce the RHIC results,
should be larger than one. We also studied the dynamical fluctuations
of . It is obvious that the energy-dependence of
these dynamical fluctuations is non-monotonic.Comment: 8 pages, 2 eps figures and 1 tabl
Effects of quantum gravity on the inflationary parameters and thermodynamics of the early universe
The effects of generalized uncertainty principle (GUP) on the inflationary
dynamics and the thermodynamics of the early universe are studied. Using the
GUP approach, the tensorial and scalar density fluctuations in the inflation
era are evaluated and compared with the standard case. We find a good agreement
with the Wilkinson Microwave Anisotropy Probe data. Assuming that a quantum gas
of scalar particles is confined within a thin layer near the apparent horizon
of the Friedmann-Lemaitre-Robertson-Walker universe which satisfies the
boundary condition, the number and entropy densities and the free energy
arising form the quantum states are calculated using the GUP approach. A
qualitative estimation for effects of the quantum gravity on all these
thermodynamic quantities is introduced.Comment: 15 graghes, 7 figures with 17 eps graph
De Novo Evolutionary Emergence of a Symmetrical Protein Is Shaped by Folding Constraints.
Molecular evolution has focused on the divergence of molecular functions, yet we know little about how structurally distinct protein folds emerge de novo. We characterized the evolutionary trajectories and selection forces underlying emergence of β-propeller proteins, a globular and symmetric fold group with diverse functions. The identification of short propeller-like motifs (<50 amino acids) in natural genomes indicated that they expanded via tandem duplications to form extant propellers. We phylogenetically reconstructed 47-residue ancestral motifs that form five-bladed lectin propellers via oligomeric assembly. We demonstrate a functional trajectory of tandem duplications of these motifs leading to monomeric lectins. Foldability, i.e., higher efficiency of folding, was the main parameter leading to improved functionality along the entire evolutionary trajectory. However, folding constraints changed along the trajectory: initially, conflicts between monomer folding and oligomer assembly dominated, whereas subsequently, upon tandem duplication, tradeoffs between monomer stability and foldability took precedence.We thank Michael Gurevitz (Tel Aviv University), John Finnerty (Boston University) and Adam Reitzel (Woodshole Oceanographic Institute) for providing N. vectensis cDNA, and Joseph Rogers (University of Cambridge) for discussion and assistance. We thank Liam Longo, Ron Milo and Balaji Santhanam for insightful comments on this manuscript. This work was supported by the Israel Science Foundation grant 980/14 (DST), the Weizmann - UK Joint Research Program (DST and JC), the Weizmann Koshland and Dean of Faculty fellowships (RGS) and an EMBO short-term fellowship (RGS). JC is a Wellcome Trust Fellow (WT 095195).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.cell.2015.12.02
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