The global polarization of Λ hyperons along the total orbital angular momentum of a relativistic heavy-ion collision is presented based on the high statistics data samples collected in Au+Au ...collisions at sNN=2.4 GeV and Ag+Ag at 2.55 GeV with the High-Acceptance Di-Electron Spectrometer (HADES) at GSI, Darmstadt. This is the first measurement below the strangeness production threshold in nucleon-nucleon collisions. Results are reported as a function of the collision centrality as well as a function of the hyperon's transverse momentum (pT) and rapidity (yCM) for the range of centrality 0–40%. We observe a strong centrality dependence of the polarization with an increasing signal towards peripheral collisions. For mid-central (20 – 40%) collisions the polarization magnitudes are 〈PΛ〉(%)=6.8±1.3(stat.)±2.1(syst.) for Au+Au and 〈PΛ〉(%)=6.2±0.4(stat.)±0.6(syst.) for Ag+Ag, which are the largest values observed so far. This observation thus provides a continuation of the increasing trend previously observed by STAR and contrasts expectations from recent theoretical calculations predicting a maximum in the region of collision energies about 3 GeV. The observed polarization is of a similar magnitude as predicted by 3D-fluid-dynamics and the UrQMD plus thermal vorticity model and significantly above results from the AMPT model.
J/ψ suppression has long been considered a sensitive signature of the formation of the Quark-Gluon Plasma (QGP) in relativistic heavy-ion collisions. In this letter, we present the first measurement ...of inclusive J/ψ production at mid-rapidity through the dimuon decay channel in Au+Au collisions at sNN=200 GeV with the STAR experiment. These measurements became possible after the installation of the Muon Telescope Detector was completed in 2014. The J/ψ yields are measured in a wide transverse momentum (pT) range of 0.15 GeV/c to 12 GeV/c from central to peripheral collisions. They extend the kinematic reach of previous measurements at RHIC with improved precision. In the 0-10% most central collisions, the J/ψ yield is suppressed by a factor of approximately 3 for pT>5 GeV/c relative to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The J/ψ nuclear modification factor displays little dependence on pT in all centrality bins. Model calculations can qualitatively describe the data, providing further evidence for the color-screening effect experienced by J/ψ mesons in the QGP.
Quark interactions with topological gluon configurations can induce chirality imbalance and local parity violation in quantum chromodynamics. This can lead to electric charge separation along the ...strong magnetic field in relativistic heavy-ion collisions – the chiral magnetic effect (CME). We report measurements by the STAR collaboration of a CME-sensitive observable in p+Au and d+Au collisions at 200 GeV, where the CME is not expected, using charge-dependent pair correlations relative to a third particle. We observe strong charge-dependent correlations similar to those measured in heavy-ion collisions. This bears important implications for the interpretation of the heavy-ion data.
Here, we report a measurement of cumulants and correlation functions of event-by-event proton multiplicity distributions from fixed-target Au+Au collisions at $\sqrt{s_\text{NN}}$ = 3 GeV measured by ...the STAR experiment. Protons are identified within the rapidity (y) and transverse momentum ($p_T$) region –0:9 < $\textit{y}$ < 0 and 0:4 < pT < 2:0 GeV/c in the center-of-mass frame. A systematic analysis of the proton cumulants and correlation functions up to sixth-order as well as the corresponding ratios as a function of the collision centrality, $p_T$, and $\textit{y}$ are presented. The effect of pileup and initial volume fluctuations on these observables and the respective corrections are discussed in detail. The results are compared to calculations from the hadronic transport UrQMD model as well as a hydrodynamic model. In the most central 5% collisions, the value of proton cumulant ratio $C_4 = C_2$ is negative, drastically different from the values observed in Au+Au collisions at higher energies. Compared to model calculations including Lattice QCD, a hadronic transport model, and a hydrodynamic model, the strong suppression in the ratio of $C_4/C_2$ at 3 GeV Au+Au collisions indicates an energy regime dominated by hadronic interactions.
We report systematic measurements of bulk properties of the system created in Au+Au collisions at √sNN = 14.5 GeV recorded by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The ...transverse momentum spectra of π±, K± and p(p¯) are studied at mid-rapidity (|y| < 0.1) for nine centrality intervals. The centrality, transverse momentum (pT), and pseudorapidity (η) 3 dependence of inclusive charged particle elliptic flow (v2), and rapidity-odd charged particles directed flow (v1) results near mid-rapidity are also presented. These measurements are compared with the published results from Au+Au collisions at other energies, and from Pb+Pb collisions at √sNN =2.76 TeV. The results at √sNN = 14.5 GeV show similar behavior as established at other energies and fit well in the energy dependence trend. These results are important as the 14.5 GeV energy fills the gap in μB, which is of the order of 100 MeV, between √sNN =11.5 and 19.6 GeV. Comparisons of the data with UrQMD and AMPT models show poor agreement in general.
ABSTRACT We investigate the effects of auditor-wrongdoer reputations for performance and likeability on fellow auditors' intentions to take action in response to a questionable audit act. We also use ...this context to explore auditor selection of reporting outlets, when they do choose to take action. In an experiment with 181 auditors, main effects suggest that likeability reputation is a significant determinant of intention to take action, while performance reputation is marginally significant. As expected, interaction results indicate that auditors have the greatest intention to take action against less likeable, poor performers. Contrary to expectations, intention to take action against a more likeable, good performer is no lower than the mixed conditions. Thus, the influence of the two dimensions of reputation is complex. Additionally, we find auditors are more likely to whistle-blow internally than externally, and through non-anonymous outlets than anonymous outlets. Our contributions include exploring the impact of reputation on the actions of third parties, and advancing prior literature by considering the influence of wrongdoer attributes on reporting decisions and auditors' reporting channel preferences. Data Availability: Data are available from the first author upon request.
The colonial tunicate
Didemnum vexillum
has recently invaded the North American coast and has the potential to cause economic and ecological damage. One potential mechanism for adult
D. vexillum
...colonies to disperse is fragmentation and subsequent reattachment to another substrate. To understand the life history and ecology of
D. vexillum
and obtain a first-order estimate of dispersal potential via fragmentation, (1) the basic material properties of
D. vexillum
sampled from two locations in southern New England were measured in two growth forms (i.e., encrusting and tendril forms); (2) summer calcium concentration was measured as a proxy for spicule densities; and (3) the environmental stress factor (ESF) of tendrils under various hydrodynamic circumstances (i.e., water velocities from 0.01 to 20 m s
−1
) was determined. Results show that
D. vexillum
colonies have high tensile strengths compared to other colonial tunicates. Colonies with higher calcium concentration tended to have greater elastic modulus (resistance to deformation). Calculations of ESF suggest that tidal currents are insufficient to cause fragmentation; however, wave-generated (in rare circumstances) and mechanical forces from vessels and trawl equipment may cause fragmentation.
In relativistic heavy-ion collisions, a global spin polarization, PH, of Λ and Λ¯¯ hyperons along the direction of the system angular momentum was discovered and measured across a broad range of ...collision energies and demonstrated a trend of increasing PH with decreasing $\sqrt{s{NN}}$. A splitting between Λ and Λ¯¯ polarization may be possible due to their different magnetic moments in a late-stage magnetic field sustained by the quark-gluon plasma which is formed in the collision. The results presented in this study find no significant splitting at the collision energies of $\sqrt{s{NN}}$ = 19.6 and 27 GeV in the BNL Relativistic Heavy Ion Collisions Beam Energy Scan Phase II using the STAR detector, with an upper limit of PΛ¯¯ – PΛ < 0.24 % and PΛ¯¯ – PΛ < 0.35 %, respectively, at a 95% confidence level. We derive an upper limit on the naive extraction of the late-stage magnetic field of B < 9.4 × 1012 T and B < 1.4 × 1013 T at $\sqrt{s{NN}}$ = 19.6 and 27 GeV, respectively, although more thorough derivations are needed. Differential measurements of PH were performed with respect to collision centrality, transverse momentum, and rapidity. With our current acceptance of |y| < 1 and uncertainties, we observe no dependence on transverse momentum and rapidity in this analysis. These results challenge multiple existing model calculations following a variety of different assumptions which have each predicted a strong dependence on rapidity in this collision-energy range.
To examine the predictors of antiretroviral adherence among HIV-infected adults, with a particular focus on advancing age, neuropsychological dysfunction, and substance abuse.
: Prospective ...observational design.
Participants were 148 HIV-infected adults between the ages of 25 and 69 years, all on a self-administered antiretroviral regimen. Medication adherence was tracked over a one-month period using an electronic monitoring device (medication event monitoring system caps). All participants completed a comprehensive battery of neuropsychological tests as well as a structured psychiatric interview.
The mean adherence rate for the entire cohort was 80.7%, with older patients (> or = 50 years) demonstrating significantly better medication adherence than younger patients (87.5 versus 78.3%). Logistic regression analyses found that older patients were three times more likely to be classified as good adherers (defined as > or = 95% adherent). Neurocognitive impairment conferred a 2.5 times greater risk of poor adherence. Among the older patients, those who were classified as poor adherers performed significantly worse on neuropsychological testing, particularly on measures of executive function and psychomotor speed. Current drug abuse/dependence, but not current alcohol abuse/dependence, was also associated with sub-optimal medication adherence.
Although older age is associated with higher rates of antiretroviral adherence, older participants who were cognitively impaired showed disproportionate difficulty in adequately adhering to their medication regimen. As such, efforts to detect neuropsychological dysfunction, particularly among older patients, and a thorough assessment of substance abuse, appear to be essential for the effective treatment of HIV-infected adults.
A decisive experimental test of the Chiral Magnetic Effect (CME) is considered one of the major scientific goals at the Relativistic Heavy-Ion Collider (RHIC) towards understanding the nontrivial ...topological fluctuations of the Quantum Chromodynamics vacuum. In heavy-ion collisions, the CME is expected to result in a charge separation phenomenon across the reaction plane, whose strength could be strongly energy dependent. The previous CME searches have been focused on top RHIC energy collisions. In this Letter, we present a low energy search for the CME in Au+Au collisions at sNN=27 GeV. We measure elliptic flow scaled charge-dependent correlators relative to the event planes that are defined at both mid-rapidity |η|<1.0 and at forward rapidity 2.1<|η|<5.1. We compare the results based on the directed flow plane (Ψ1) at forward rapidity and the elliptic flow plane (Ψ2) at both central and forward rapidity. The CME scenario is expected to result in a larger correlation relative to Ψ1 than to Ψ2, while a flow driven background scenario would lead to a consistent result for both event planes. In 10-50% centrality, results using three different event planes are found to be consistent within experimental uncertainties, suggesting a flow driven background scenario dominating the measurement. We obtain an upper limit on the deviation from a flow driven background scenario at the 95% confidence level. This work opens up a possible road map towards future CME search with the high statistics data from the RHIC Beam Energy Scan Phase-II.
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