Examining a reduced jet-medium coupling in Pb+Pb collisions at the Large Hadron Collider

Recent data on the nuclear modification factor $R_{AA}$ 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 $R_{AA}(\sqrt{s},p_T,b)$ and the elliptic flow $v_2(\sqrt{s},p_T,b)$ at $\sqrt{s}=0.2,2.76$ ATeV over a transverse momentum range $p_T$ 10-100 GeV and a broad impact parameter, b, range. We use a simple analytic "polytrope" model ($dE/dx=- \kappa E^{a} x^z T^{c}$) 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 $\kappa$ 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 $R_{AA}$ with $p_T$>10 GeV combined with the slow variation of the asymptotic $v_2(p_T)$ at the LHC rules out popular exponential geometric optics models (a=1). The LHC data are compatible with $0\leq a\leq 1/3$ 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-$p_T$ 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 $v_n(N_{part})$ vs. $v_n^{I_{AA}}(N_{part})$ 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 $R_{AA}$-data, once the parameters of the energy-loss model are fixed from $R_{AA}$-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

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