Probing Gluon Spin-Momentum Correlations in Transversely Polarized Protons through Midrapidity Isolated Direct Photons in p

Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in p^{↑}+p collisions at sqrt[s]=200 GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a 50-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.

Experimental Demonstration of Hadron Beam Cooling Using Radio-Frequency Accelerated Electron Bunches.

Cooling of beams of gold ions using electron bunches accelerated with radio-frequency systems was recently experimentally demonstrated in the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Such an approach is new and opens the possibility of using this technique at higher energies than possible with electrostatic acceleration of electron beams. The challenges of this approach include generation of electron beams suitable for cooling, delivery of electron bunches of the required quality to the cooling sections without degradation of beam angular divergence and energy spread, achieving the required small angles between electron and ion trajectories in the cooling sections, precise velocity matching between the two beams, high-current operation of the electron accelerator, as well as several physics effects related to bunched-beam cooling. Here we report on the first demonstration of cooling hadron beams using this new approach.

Nuclear Dependence of the Transverse Single-Spin Asymmetry in the Production of Charged Hadrons at Forward Rapidity in Polarized p+p, p+Al, and p+Au Collisions at sqrt[s_{NN}]=200 GeV.

We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively charged hadrons in polarized p^{↑}+p, p^{↑}+Al, and p^{↑}+Au collisions at sqrt[s_{NN}]=200 GeV. The measurements have been performed at forward rapidity (1.4<η<2.4) over the range of transverse momentum (1.8

Measurements of Multiparticle Correlations in d+Au Collisions at 200, 62.4, 39, and 19.6 GeV and p+Au Collisions at 200 GeV and Implications for Collective Behavior.

Recently, multiparticle-correlation measurements of relativistic p/d/^{3}He+Au, p+Pb, and even p+p collisions show surprising collective signatures. Here, we present beam-energy-scan measurements of two-, four-, and six-particle angular correlations in d+Au collisions at sqrt[s_{NN}]=200, 62.4, 39, and 19.6 GeV. We also present measurements of two- and four-particle angular correlations in p+Au collisions at sqrt[s_{NN}]=200 GeV. We find the four-particle cumulant to be real valued for d+Au collisions at all four energies. We also find that the four-particle cumulant in p+Au has the opposite sign as that in d+Au. Further, we find that the six-particle cumulant agrees with the four-particle cumulant in d+Au collisions at 200 GeV, indicating that nonflow effects are subdominant. These observations provide strong evidence that the correlations originate from the initial geometric configuration, which is then translated into the momentum distribution for all particles, commonly referred to as collectivity.

Nuclear Dependence of the Transverse-Single-Spin Asymmetry for Forward Neutron Production in Polarized p+A Collisions at sqrt[s_{NN}]=200 GeV.

During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p+p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p+p collisions predicts only a moderate atomic-mass-number (A) dependence. In contrast, the asymmetries observed at RHIC in p+A collisions showed a surprisingly strong A dependence in inclusive forward neutron production. The observed asymmetry in p+Al collisions is much smaller, while the asymmetry in p+Au collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed A dependence.

Determinants of vitamin D deficiency among undergraduate medical students in Saudi Arabia.

BACKGROUND/OBJECTIVES: The objectives of our study were to determine possible factors associated with low vitamin D levels in medical students. SUBJECTS/METHODS: A cross-sectional study was performed among 255 first- to fifth-year male undergraduate medical students of one of the major universities in Saudi Arabia. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using electrochemiluminiscence. Multiple logistic regression analysis was performed. RESULTS: Majority of Saudi medical students (75.2%) had 25(OH)D levels <30 nmol/l, defined as risk for deficiency by the Institute of Medicine. Multivariate analysis showed that the odds of having 25(OH)D serum levels of ⩾ 30 nmol/l were seven times higher both in students who took vitamin D (odds ratio (OR)=7.2, 95% confidence interval (CI)=1.8-29.9, P=0.006) or multivitamin supplements (OR=6.9, 95% CI=1.7-27.3, P=0.006) within 1 year. Students with a history of vitamin D testing >1 year before the study or moderate/vigorous physical activity (PA) had 4.4 (OR=4.4, 95% CI=1.7-11.4, P=0.003) and 2.7-fold (OR=2.7, 95% CI=1.3-5.3, P=0.006) higher odds of having 25(OH)D levels ⩾ 30 nmol/l, respectively. There was no significant association between 25(OH)D serum levels and average time spent outdoors per day (P=0.369) and type of clothing (long-sleeved vs short-sleeved; P=0.800). CONCLUSIONS: Vitamin D deficiency was highly prevalent in Saudi medical students. Modifiable factors such as vitamin D intake and PA could be targeted for intervention. Further studies with standardized laboratory measurements of 25(OH)D are needed to explore the role of vitamin D testing in behavioral change, which may lead to increased serum 25(OH)D levels.

Prevalence of antibodies to hepatitis C virus in Saudi and expatriate women in Riyadh, Saudi Arabia.

Six of 511 (1.17%) parturient Saudi females were positive for antibodies to hepatitis C virus (HCV), while one of 171 (0.58%) expatriate female nurses tested positive for the antibody. The prevalence of 1.17% in Saudis compares with 1.2% among pregnant women in Spain, while none of the 40 pregnant women screened in England tested positive for anti-HCV. Antibodies to hepatitis B core antigen in the same sample from Saudi women were positive in 24.6%. Judging by the low prevalence of its antibody, HCV is not as highly endemic as hepatitis B virus (HBV) in this population.

Prevalence of antibodies to hepatitis C virus in Saudi patients with chronic liver disease.

The prevalence of antibodies to hepatitis C virus (anti-HCV) has been measured in 113 Saudi patients with chronic liver diseases. Twenty-five percent of 20 patients with hepatocellular carcinoma (HCC) were positive for anti-HCV and 29.7% of 38 patients with cirrhosis and 27.3% of 33 patients with liver fibrosis, respectively, also tested positive. The positivity rate for a miscellany of liver diseases (22) was 13.6%. The differences between these prevalence rates were not statistically significant. By comparison, 45% of HCC tested positive for hepatitis B surface antigen (HBsAg) while 52.7% of cirrhosis cases were positive. There rates were statistically significant when compared with HBsAg positivity rates of 9.1% and 18.2% in the liver fibrosis and miscellaneous groups. The role of hepatitis C virus (HCV) may be secondary or additive in the causation of chronic liver disease and hepatocellular carcinoma in this environment in which hepatitis B virus (HBV) is highly endemic.

Prevalence of antibodies to hepatitis C virus in hemodialysis patients in Riyadh.

Prevalence of antibodies to hepatitis C virus (anti-HCV) was determined in 190 adults (mean age 40.4 years; range 15 to 75) with end-stage renal disease (ESRD) who are on regular hemodialysis in the Nephrology Unit, Riyadh Central Hospital. The overall prevalence rate was 53.7% (48.7% and 61.0% in Saudi's and expatriates, respectively). These figures are considerably higher than figures of 34.8% reported from hemodialysis units in Riyadh, 20% in Spain, 5.5% in Germany, and 1% in the United Kingdom. The possible reasons for the high prevalence of this marker of HCV in our hemodialysis unit are considered and suggestions made for its control.

Prevalence of antibodies to hepatitis C virus in blood donors in Riyadh.

Prevalence of antibodies to hepatitis C virus (anti-HCV) was determined in 580 voluntary blood donors in Riyadh. Among 403 Saudis screened, the prevalence was 1.24%, while among 177 expatriates screened the prevalence was 4.52%. The difference was statistically significant (P<0.02; x(2)test). The overall prevalence of 2.24% is lower than that reported in Spain (7.3%) but higher than reports from the United Kingdom (0.5 to 1%0, Italy (0.87%), or Germany (0.24 to 0.79%0. In view of reports that blood positive for anti-HCV can transmit non-A, non-B hepatitis, it is advisable to routinely screen donor blood for anti-HCV.