85 research outputs found
Examining a reduced jet-medium coupling in Pb+Pb collisions at the Large Hadron Collider
Recent data on the nuclear modification factor of jet fragments in
2.76 ATeV Pb+Pb collisions at the Large Hadron Collider (LHC) indicate that the
jet-medium coupling in a Quark-Gluon Plasma (QGP) is reduced at LHC energies
and not compatible with the coupling deduced from data at the Relativistic
Hadron Collider (RHIC). We estimate the reduction factor from a combined fit to
the available data on and the elliptic flow
at ATeV over a transverse momentum
range 10-100 GeV and a broad impact parameter, b, range. We use a simple
analytic "polytrope" model () to investigate
the dynamical jet-energy loss model dependence. Varying a=0-1 interpolates
between weakly-coupled and strongly-coupled models of jet-energy dependence
while z=0-2 covers a wide range of possible jet-path dependencies from elastic
and radiative to holographic string mechanisms. Our fit to LHC data indicates
an approximate 40% reduction of the coupling from RHIC to LHC and
excludes energy-loss models characterized by a jet-energy exponent with a>1/3.
In particular, the rapid rise of with >10 GeV combined with the
slow variation of the asymptotic at the LHC rules out popular
exponential geometric optics models (a=1). The LHC data are compatible with
pQCD-like energy-loss models where the jet-medium coupling is
reduced by approximately 10% between RHIC and LHC.Comment: 10 pages, 7 figures, version published in Physical Review
Fourier Harmonics of High-pT Particles Probing the Fluctuating Intitial Condition Geometries in Heavy-Ion Collisions
Second Fourier harmonics of jet quenching have been thoroughly explored in
the literature and shown to be sensitive to the underlying jet path-length
dependence of energy loss and the differences between the mean eccentricity
predicted by Glauber and CGC/KLN models of initial conditions. We compute the
jet path-length dependence of energy-loss for higher azimuthal harmonics of
jet-fragments in a generalized model of energy-loss for RHIC energies and find,
however, that even the high- second moment is most sensitive to the poorly
known early-time evolution during the first fm/c. Moreover, we demonstrate that
higher-jet harmonics are remarkably insensitive to the initial conditions,
while the different vs. correlations
between the moments of monojet and dijet nuclear modifications factors remain a
most sensitive probe to differentiate between Glauber and CGC/KLN initial state
sQGP geometries.Comment: 6 pages, 7 figures, updated figures, version accepted for publication
in Phys. Rev.
Mini black holes at the LHC : discovery through di-jet suppression, mono-jet emission and a supersonic boom in the quark-gluon plasma in ALICE, ATLAS and CMS
We examine experimental signatures of TeV-mass black hole formation in heavy ion collisions at the LHC. We find that the black hole production results in a complete disappearance of all very high p_T (> 500 GeV) back-to-back correlated di-jets of total mass M > M_f ~ 1 TeV. We show that the subsequent Hawking-decay produces multiple hard mono-jets and discuss their detection. We study the possibility of cold black hole remnant (BHR) formation of mass ~ M_f and the experimental distinguishability of scenarios with BHRs and those with complete black hole decay. Finally we point out that a Heckler-Kapusta-Hawking plasma may form from the emitted mono-jets. In this context we present new simulation data of Mach shocks and of the evolution of initial conditions until the freeze-out
Universal Flow-Driven Conical Emission in Ultrarelativistic Heavy-Ion Collisions
The double-peak structure observed in soft-hard hadron correlations is
commonly interpreted as a signature for a Mach cone generated by a supersonic
jet interacting with the hot and dense medium created in ultrarelativistic
heavy-ion collisions. We show that it can also arise due to averaging over many
jet events in a transversally expanding background. We find that the
jet-induced away-side yield does not depend on the details of the
energy-momentum deposition in the plasma, the jet velocity, or the system size.
Our claim can be experimentally tested by comparing soft-hard correlations
induced by heavy-flavor jets with those generated by light-flavor jets.Comment: 4 pages, 3 figure
Sensitivity of Azimuthal Jet Tomography to Early Time Energy-Loss at RHIC and LHC
We compute the jet path-length dependence of energy-loss for higher azimuthal
harmonics of jet-fragments in a generalized model of energy-loss that can
interpolate between pQCD and AdS/CFT limits and compare results with Glauber
and CGC/KLN initial conditions. We find, however, that even the high-pT second
moment is most sensitive to the poorly known early-time evolution during the
first fm/c. Moreover, we demonstrate that quite generally the energy and
density-dependence leads to an overquenching jet fragments relative to the
first LHC -data, once the parameters of the energy-loss model are fixed
from -data at RHIC.Comment: 4 pages, 2 figures, version accepted for publication in J. Phys. G:
Nucl. Part. Phys. as conference proceedings for Quark Matter 2011, May 23 -
May 28, Annecy, Franc
Are there plasminos in superconductors?
Hot and/or dense, normal-conducting systems of relativistic fermions exhibit
a particular collective excitation, the so-called plasmino. We compute the
one-loop self-energy, the dispersion relation and the spectral density for
fermions interacting via attractive boson exchange. It is shown that plasminos
also exist in superconductors.Comment: 15 pages, 14 figures, revte
Universality of the Diffusion Wake from Stopped and Punch-Through Jets in Heavy-Ion Collisions
We solve (3+1)-dimensional ideal hydrodynamical equations with source terms
that describe punch-through and fully stopped jets in order to compare their
final away-side angular correlations in a static medium. For fully stopped
jets, the backreaction of the medium is described by a simple Bethe-Bloch-like
model which leads to an explosive burst of energy and momentum (Bragg peak)
close to the end of the jet's evolution through the medium. Surprisingly
enough, we find that the medium's response and the corresponding away-side
angular correlations are largely insensitive to whether the jet punches through
or stops inside the medium. This result is also independent of whether momentum
deposition is longitudinal (as generally occurs in pQCD energy loss models) or
transverse (as the Bethe-Bloch formula implies). The existence of the diffusion
wake is therefore shown to be universal to all scenarios where momentum as well
as energy is deposited into the medium, which can readily be understood in
ideal hydrodynamics through vorticity conservation. The particle yield coming
from the strong forward moving diffusion wake that is formed in the wake of
both punch-through and stopped jets largely overwhelms their weak Mach cone
signal after freeze-out.Comment: 9 pages, 6 figures, revised version, main results unchange
Thrombolytic removal of intraventricular haemorrhage in treatment of severe stroke: results of the randomised, multicentre, multiregion, placebo-controlled CLEAR III trial
Background:
Intraventricular haemorrhage is a subtype of intracerebral haemorrhage, with 50% mortality and serious disability for survivors. We aimed to test whether attempting to remove intraventricular haemorrhage with alteplase versus saline irrigation improved functional outcome.
Methods:
In this randomised, double-blinded, placebo-controlled, multiregional trial (CLEAR III), participants with a routinely placed extraventricular drain, in the intensive care unit with stable, non-traumatic intracerebral haemorrhage volume less than 30 mL, intraventricular haemorrhage obstructing the 3rd or 4th ventricles, and no underlying pathology were adaptively randomly assigned (1:1), via a web-based system to receive up to 12 doses, 8 h apart of 1 mg of alteplase or 0·9% saline via the extraventricular drain. The treating physician, clinical research staff, and participants were masked to treatment assignment. CT scans were obtained every 24 h throughout dosing. The primary efficacy outcome was good functional outcome, defined as a modified Rankin Scale score (mRS) of 3 or less at 180 days per central adjudication by blinded evaluators. This study is registered with ClinicalTrials.gov, NCT00784134.
Findings:
Between Sept 18, 2009, and Jan 13, 2015, 500 patients were randomised: 249 to the alteplase group and 251 to the saline group. 180-day follow-up data were available for analysis from 246 of 249 participants in the alteplase group and 245 of 251 participants in the placebo group. The primary efficacy outcome was similar in each group (good outcome in alteplase group 48% vs saline 45%; risk ratio [RR] 1·06 [95% CI 0·88–1·28; p=0·554]). A difference of 3·5% (RR 1·08 [95% CI 0·90–1·29], p=0·420) was found after adjustment for intraventricular haemorrhage size and thalamic intracerebral haemorrhage. At 180 days, the treatment group had lower case fatality (46 [18%] vs saline 73 [29%], hazard ratio 0·60 [95% CI 0·41–0·86], p=0·006), but a greater proportion with mRS 5 (42 [17%] vs 21 [9%]; RR 1·99 [95% CI 1·22–3·26], p=0·007). Ventriculitis (17 [7%] alteplase vs 31 [12%] saline; RR 0·55 [95% CI 0·31–0·97], p=0·048) and serious adverse events (114 [46%] alteplase vs 151 [60%] saline; RR 0·76 [95% CI 0·64–0·90], p=0·002) were less frequent with alteplase treatment. Symptomatic bleeding (six [2%] in the alteplase group vs five [2%] in the saline group; RR 1·21 [95% CI 0·37–3·91], p=0·771) was similar.
Interpretation:
In patients with intraventricular haemorrhage and a routine extraventricular drain, irrigation with alteplase did not substantially improve functional outcomes at the mRS 3 cutoff compared with irrigation with saline. Protocol-based use of alteplase with extraventricular drain seems safe. Future investigation is needed to determine whether a greater frequency of complete intraventricular haemorrhage removal via alteplase produces gains in functional status
Bioarchaeology of Neolithic Çatalhöyük Reveals Fundamental Transitions in Health, Mobility, and Lifestyle in Early Farmers
The transition from a human diet based exclusively on wild plants and animals to one involving dependence on domesticated plants and animals beginning 10,000 to 11,000 y ago in Southwest Asia set into motion a series of profound health, lifestyle, social, and economic changes affecting human populations throughout most of the world. However, the social, cultural, behavioral, and other factors surrounding health and lifestyle associated with the foraging-to-farming transition are vague, owing to an incomplete or poorly understood contextual archaeological record of living conditions. Bioarchaeological investigation of the extraordinary record of human remains and their context from Neolithic Çatalhöyük (7100–5950 cal BCE), a massive archaeological site in south-central Anatolia (Turkey), provides important perspectives on population dynamics, health outcomes, behavioral adaptations, interpersonal conflict, and a record of community resilience over the life of this single early farming settlement having the attributes of a protocity. Study of Çatalhöyük human biology reveals increasing costs to members of the settlement, including elevated exposure to disease and labor demands in response to community dependence on and production of domesticated plant carbohydrates, growing population size and density fueled by elevated fertility, and increasing stresses due to heightened workload and greater mobility required for caprine herding and other resource acquisition activities over the nearly 12 centuries of settlement occupation. These changes in life conditions foreshadow developments that would take place worldwide over the millennia following the abandonment of Neolithic Çatalhöyük, including health challenges, adaptive patterns, physical activity, and emerging social behaviors involving interpersonal violence
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Prevalence of Potentially Inappropriate Medication use in older drivers
Background
Potentially Inappropriate Medication (PIM) use has been studied in a variety of older adult populations across the world. We sought to examine the prevalence and correlates of PIM use in older drivers.
Methods
We applied the American Geriatrics Society 2015 Beers Criteria to baseline data collected from the “brown-bag” review of medications for participants of the Longitudinal Research on Aging Drivers (LongROAD) study to examine the prevalence and correlates of PIM use in a geographically diverse, community-dwelling sample of older drivers (n = 2949). Proportions of participants who used one or more PIMs according to the American Geriatrics Society 2015 Beers Criteria, and estimated odds ratios (ORs) and 95% confidence intervals (CIs) of PIM use associated with participant characteristics were calculated.
Results
Overall, 18.5% of the older drivers studied used one or more PIM. The most commonly used therapeutic category of PIM was benzodiazepines (accounting for 16.6% of the total PIMs identified), followed by nonbenzodiazepine hypnotics (15.2%), antidepressants (15.2%), and first-generation antihistamines (10.5%). Compared to older drivers on four or fewer medications, the adjusted ORs of PIM use were 2.43 (95% CI 1.68–3.51) for those on 5–7 medications, 4.19 (95% CI 2.95–5.93) for those on 8–11 medications, and 8.01 (95% CI 5.71–11.23) for those on ≥12 medications. Older drivers who were female, white, or living in urban areas were at significantly heightened risk of PIM use.
Conclusion
About one in five older drivers uses PIMs. Commonly used PIMs are medications known to impair driving ability and increase crash risk. Implementation of evidence-based interventions to reduce PIM use in older drivers may confer both health and safety benefits.
Trial registration
Not applicable
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