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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.

The Fourier harmonics,$$v_2$$v 2 and$$v_3$$v 3 of negative pions are measured at center-of-mass energy per nucleon pair of$$\\sqrt{s_{\\textrm{NN}}}$$s NN = 17.3 GeV around midrapidity by the CERES/NA45 experiment at the CERN SPS in 0–30% central PbAu collisions with a mean centrality of 5.5%. The analysis is performed in two centrality bins as a function of the transverse momentum$$\\mathrm {p_{\\textrm{T}}}$$p T from 0.05 GeV/ c to more than 2 GeV/ c . This is the first measurement of the$$v^{1/3}_{3}/v^{1/2}_{2}$$v 3 1 / 3 / v 2 1 / 2 ratio as a function of transverse momentum at SPS energies, that reveals, independently of the hydrodynamic models, hydrodynamic behavior of the formed system. For$$\\mathrm {p_{\\textrm{T}}}$$p T above 0.5 GeV/ c , the ratio is nearly flat in accordance with the hydrodynamic prediction and as previously observed by the ATLAS and ALICE experiments at the much higher LHC energies. The results are also compared with the SMASH-vHLLE hybrid model predictions, as well as with the SMASH model applied alone.

The Fourier harmonics, v 2 and v 3 of negative pions are measured at center-of-mass energy per nucleon pair of s NN = 17.3 GeV around midrapidity by the CERES/NA45 experiment at the CERN SPS in 0–30% central PbAu collisions with a mean centrality of 5.5%. The analysis is performed in two centrality bins as a function of the transverse momentum p T from 0.05 GeV/ c to more than 2 GeV/ c . This is the first measurement of the v 3 1 / 3 / v 2 1 / 2 ratio as a function of transverse momentum at SPS energies, that reveals, independently of the hydrodynamic models, hydrodynamic behavior of the formed system. For p T above 0.5 GeV/ c , the ratio is nearly flat in accordance with the hydrodynamic prediction and as previously observed by the ATLAS and ALICE experiments at the much higher LHC energies. The results are also compared with the SMASH-vHLLE hybrid model predictions, as well as with the SMASH model applied alone.

The Beam Energy Scan phase II (BES-II), performed in the Relativistic Heavy Ion Collider (RHIC) from 2019 to 2021, explored the phase transition between quark-gluon plasma and hadronic gas. BES-II exceeded the goal of a fourfold increase in the average luminosity over that achieved during Beam Energy Scan phase I (BES-I), at five gold beam energies: 9.8, 7.3, 5.75, 4.59, and3.85GeV/nucleon. This was accomplished by addressing several beam dynamics effects, including intrabeam scattering, beam-beam, space charge, beam instability, and field errors induced by superconducting magnet persistent currents. Some of these effects are especially detrimental at low energies. BES-II achievements are presented, and the measures taken to improve RHIC performance are described. These measures span the whole RHIC complex, including ion beam sources, injectors, beam lifetime improvements in RHIC, and operation with the world’s first bunched beam Low Energy RHIC electron Cooler (LEReC).

A hollow electron beam has been proposed as an active control tool to remove the beam halo from high-energy, high-current hadron or ion machines (such as the High-Luminosity Large Hadron Collider). To study the halo removal rate and assess the effect on the ion beam core, one of the two electron lenses in the Relativistic Heavy Ion Collider was changed from a Gaussian beam profile to a hollow profile. We describe the design and verification of the hollow electron beam parameters as well as the methods to minimize the hollow beam profile distortions, which can result in an ion beam emittance increase. The hollow beam alignment with the ion beam by using a backscattered electron detector has been demonstrated. Furthermore, experiments were carried out to explore the efficiency of the halo removal by scanning the current and inner radius of the hollow electron beam, which is pulsed either every turn or every nth turn. The effects of the hollow electron beam on the ion beam emittance and luminosity were also assessed experimentally by scanning the inner radius of the electron beam.

The first electron cooling with rf-accelerated electron bunches was recently demonstrated at the low energy RHIC electron cooler (LEReC) at BNL. Successful cooling requires that the electrons in the cooling section have a small angular spread and are well aligned with respect to the copropagating ions. LEReC puts into practice a nonmagnetized cooling of the ions at Lorentz factors ofγ=4.1and 4.9. Hence, unlike in previous coolers, in which the transverse electron dynamics is constrained by longitudinal solenoid fields, the ion-electron focusing and steering strongly contribute to the average angular spread of the electron beam. In this paper we discuss the factors that affect the electron angles and describe the process of tuning the electron beam to maximize the cooling of ion bunches in RHIC.

The world’s first electron cooling based on the rf acceleration of electron bunches was experimentally demonstrated at the Low Energy RHIC Electron Cooler (LEReC) at Brookhaven National Laboratory. The critical step in obtaining cooling of the Au ions in the collider with this new approach was matching the electron and ion relativisticγ-factors with a relative error of less than5×10−4. Since the electron beam kinetic energy was just 1.6 MeV, it was required to set the absolute energy of electrons with an accuracy better than 0.8 keV. The method of setting electron energy in conventional coolers was unsuitable for LEReC and a new technique had to be developed. In this paper we describe our experience with measuring the electron beam energy at LEReC and precisely matching electron and ionγ-factors, which resulted in demonstration of the cooling.

A head-on beam-beam compensation scheme was implemented for operation in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory [Phys. Rev. Lett. 115, 264801 (2015)]. The compensation consists of electron lenses for the reduction of the beam-beam induced tune spread, and a lattice for the minimization of beam-beam generated resonance driving terms. We describe the implementations of the lattice and electron lenses, and report on measurements of lattice properties and the effect of the electron lenses on the hadron beam.

After a number of years of sparse results from electromagnetic probes we have seen a revitalization of this field at this conference. Exciting first results obtained by NA60 at CERN, HADES at GSI, as well as PHENIX at RHIC, cover a broad range of initial conditions created in heavy-ion collisions. These experiments hold the promise to provide accurate new data, which will certainly furnish qualitatively new insights into matter at high temperature and density. In this paper I review the status of the field today and the perspectives for the future.

We present the combined results on electron-pair production in 158 GeV/n Pb-Au (\\(\\sqrt{s}\\) = 17.2 GeV) collisions taken at the CERN SPS in 1995 and 1996, and give a detailed account of the data analysis. The enhancement over the reference of neutral meson decays amounts to a factor of 2.31 \\(\\pm0.19 (stat.)\\pm0.55 (syst.)\\pm0.69 (decays)\\) for semi-central collisions (28\\(\\%\\)\\(\\sigma/\\sigma_{geo}\\)) when yields are integrated over m > 200 MeV/c2 in invariant mass. The measured yield, its stronger-than-linear scaling with \\(N_{\\rm ch}\\), and the dominance of low pair pt strongly suggest an interpretation as thermal radiation from pion annihilation in the hadronic fireball. The shape of the excess centring at \\(m\\approx\\) 500 MeV/c2, however, cannot be described without strong medium modifications of the \\(\\rho\\) meson. The results are put into perspective by comparison to predictions from Brown-Rho scaling governed by chiral symmetry restoration, and from the spectral-function many-body treatment in which the approach to the phase boundary is less explicit.