Effects of Single-Dose Dietary Nitrate on Oxygen Consumption During and After Maximal and Submaximal Exercise in Healthy Humans

International Journal of Exercise Science 11(3): 214-225, 2018. Dietary nitrate (NO3-) has been shown to reduce oxygen consumption (VO2) during moderate to high-intensity (e.g. time to fatigue, time trials) exercise and often in trained athletes. However, less is known regarding prolonged exercise and the potential impact of NO3- on post-exercise excess oxygen consumption (EPOC), particularly in untrained individuals, who may have different metabolic goals during exercise than trained individuals. We tested the hypothesis that acute nitrate supplementation in the form of beet root juice will significantly decrease both VO2 during maximal exercise and EPOC in both maximal and submaximal exercise trials. Eight young, moderately active, healthy males (age: 24.8±1.4 years, body mass index: 23.7±0.4 kg/m2; VO2max: 34.2±3.9 ml/kg/min) performed step-wise maximal cycle exercise (n=4) and prolonged submaximal cycle exercise (n=6) (45 min; 38±2% of max work rate) in control (anti-bacterial mouthwash) and acute NO3– supplemented conditions [70ml concentrated beet root juice (0.4g NO3-), 2 hrs prior to exercise] on separate occasions. Measurements of VO2 (indirect calorimetry), arterial blood pressure (MAP; sphygmomanometry), and heart rate (HR; ECG) were made before, during, and following exercise bouts. NO3- reduced MAP at rest ~1-3mmHg. However, NO3- had no impact on VO2 during maximal (VO2max, Ctrl: 34.2±3.9 ml/kg/min vs NO3-: 31.7±4.4 ml/kg/min), submaximal exercise (average of min 25-45, Ctrl: 24.6±2.4 ml/kg/min vs NO3-: 26.8±3.3 ml/kg/min) or EPOC (area under the curve, Ctrl: 0.57±0.24 L vs NO3-: 0.66±0.16 L). Thus, while NO3- supplementation may have performance benefits in elite athletes exercising at high intensities, in recreationally active males, there appears to be little impact on changes in VO2 due to maximal or submaximal prolonged exercise

Recent STAR results in high-energy polarized proton-proton collisions at RHIC

The STAR experiment at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is carrying out a spin physics program in high-energy polarized $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=200-500\,$GeV to gain a deeper insight into the spin structure and dynamics of the proton. One of the main objectives of the spin physics program at RHIC is the extraction of the polarized gluon distribution function based on measurements of gluon initiated processes, such as hadron and jet production. The STAR detector is well suited for the reconstruction of various final states involving jets, $\pi^{0}$, $\pi^{\pm}$, e$^{\pm}$ and $\gamma$, which allows to measure several different processes. Recent results will be shown on the measurement of jet production and hadron production at $\sqrt{s}=200\,$GeV. The RHIC spin physics program has recently completed the first data taking period in 2009 of polarized $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=500\,$GeV. This opens a new era in the study of the spin-flavor structure of the proton based on the production of $W^{-(+)}$ bosons. Recent STAR results on the first measurement of $W$ boson production in polarized $\vec{p}+\vec{p}$ collisions will be shown.Comment: 10 pages, 9 figures, Talk presented at the 26th Winter Workshop on Nuclear Dynamics, Ocho Rios, Jamaica, January 2-9, 2010 to be published in Journal of Physics: Conference Series (JPCS) The author may be contacted via: [email protected]

Recent results from the STAR spin program at RHIC

The STAR experiment uses polarized p+p collisions at RHIC to determine the contributions to the spin of the proton from gluon spin and from orbital angular momentum of the quarks and gluons. Selective STAR measurements of the longitudinal double spin asymmetry for inclusive jet and inclusive hadron production are presented here. In addition, we report measurements of the transverse spin asymmetry for di-jet production at mid-rapidity and the transverse single-spin asymmetry for forward pi0 productionComment: 4 pages, 5 figures, presented at GHP06 conferenc

Spin alignment measurements of the K∗0(892)K^{*0}(892) and ϕ(1020)\phi(1020) vector mesons at RHIC

We present the first spin alignment measurements for the $K^{*0}(892)$ and $\phi(1020)$ vector mesons produced at mid-rapidity with transverse momenta up to 5 GeV/c at $\sqrt{s_{NN}}$ = 200 GeV at RHIC. The diagonal spin density matrix elements with respect to the reaction plane in Au+Au collisions are $\rho_{00}$ = 0.32 $\pm$ 0.04 (stat) $\pm$ 0.09 (syst) for the $K^{*0}$ ($0.8<p_T<5.0$ GeV/c) and $\rho_{00}$ = 0.34 $\pm$ 0.02 (stat) $\pm$ 0.03 (syst) for the $\phi$ ($0.4<p_T<5.0$ GeV/c), and are constant with transverse momentum and collision centrality. The data are consistent with the unpolarized expectation of 1/3 and thus no evidence is found for the transfer of the orbital angular momentum of the colliding system to the vector meson spins. Spin alignments for $K^{*0}$ and $\phi$ in Au+Au collisions were also measured with respect to the particle's production plane. The $\phi$ result, $\rho_{00}$ = 0.41 $\pm$ 0.02 (stat) $\pm$ 0.04 (syst), is consistent with that in p+p collisions, $\rho_{00}$ = 0.39 $\pm$ 0.03 (stat) $\pm$ 0.06 (syst), also measured in this work. The measurements thus constrain the possible size of polarization phenomena in the production dynamics of vector mesons.Comment: 7 pages, 4 figures. fig.1 updated; one more reference added, one typo corrected, published in PRC.77.06190

System-Size Independence of Directed Flow Measured at the BNL Relativistic Heavy-Ion Collider

We measure directed flow (ν_1) for charged particles in Au+Au and Cu+Cu collisions at √S_(NN)=200 and 62.4 GeV, as a function of pseudorapidity (η), transverse momentum (p_t), and collision centrality, based on data from the STAR experiment. We find that the directed flow depends on the incident energy but, contrary to all available model implementations, not on the size of the colliding system at a given centrality. We extend the validity of the limiting fragmentation concept to ν_1 in different collision systems, and investigate possible explanations for the observed sign change in ν_1(p_t)

Longitudinal double-spin asymmetry for inclusive jet production in p+p collisions at sqrt(s)=200 GeV

We report a new STAR measurement of the longitudinal double-spin asymmetry A_LL for inclusive jet production at mid-rapidity in polarized p+p collisions at a center-of-mass energy of sqrt(s) = 200 GeV. The data, which cover jet transverse momenta 5 < p_T < 30 GeV/c, are substantially more precise than previous measurements. They provide significant new constraints on the gluon spin contribution to the nucleon spin through the comparison to predictions derived from one global fit of polarized deep-inelastic scattering measurements.Comment: 7 pages, 4 figures + 1 tabl

Measurements of ϕ\phi meson production in relativistic heavy-ion collisions at RHIC

We present results for the measurement of $\phi$ meson production via its charged kaon decay channel $\phi \to K^+K^-$ in Au+Au collisions at $\sqrt{s_{_{NN}}}=62.4$, 130, and 200 GeV, and in $p+p$ and $d$+Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV from the STAR experiment at the BNL Relativistic Heavy Ion Collider (RHIC). The midrapidity ($|y|<0.5$) $\phi$ meson transverse momentum ($p_{T}$) spectra in central Au+Au collisions are found to be well described by a single exponential distribution. On the other hand, the $p_{T}$ spectra from $p+p$, $d$+Au and peripheral Au+Au collisions show power-law tails at intermediate and high $p_{T}$ and are described better by Levy distributions. The constant $\phi/K^-$ yield ratio vs beam species, collision centrality and colliding energy is in contradiction with expectations from models having kaon coalescence as the dominant mechanism for $\phi$ production at RHIC. The $\Omega/\phi$ yield ratio as a function of $p_{T}$ is consistent with a model based on the recombination of thermal $s$ quarks up to $p_{T}\sim 4$ GeV/$c$, but disagrees at higher transverse momenta. The measured nuclear modification factor, $R_{dAu}$, for the $\phi$ meson increases above unity at intermediate $p_{T}$, similar to that for pions and protons, while $R_{AA}$ is suppressed due to the energy loss effect in central Au+Au collisions. Number of constituent quark scaling of both $R_{cp}$ and $v_{2}$ for the $\phi$ meson with respect to other hadrons in Au+Au collisions at $\sqrt{s_{_{NN}}}$=200 GeV at intermediate $p_{T}$ is observed. These observations support quark coalescence as being the dominant mechanism of hadronization in the intermediate $p_{T}$ region at RHIC.Comment: 22 pages, 21 figures, 4 table

Enhanced strange baryon production in Au+Au collisions compared to p+p at sqrts = 200 GeV

We report on the observed differences in production rates of strange and multi-strange baryons in Au+Au collisions at sqrts = 200 GeV compared to pp interactions at the same energy. The strange baryon yields in Au+Au collisions, then scaled down by the number of participating nucleons, are enhanced relative to those measured in pp reactions. The enhancement observed increases with the strangeness content of the baryon, and increases for all strange baryons with collision centrality. The enhancement is qualitatively similar to that observed at lower collision energy sqrts =17.3 GeV. The previous observations are for the bulk production, while at intermediate pT, 1 < pT< 4 GeV/c, the strange baryons even exceed binary scaling from pp yields.Comment: 7 pages, 4 figures. Printed in PR

Growth of Long Range Forward-Backward Multiplicity Correlations with Centrality in Au+Au Collisions at sNN\sqrt{s_{NN}} = 200 GeV

Forward-backward multiplicity correlation strengths have been measured with the STAR detector for Au+Au and $\textit{p+p}$ collisions at $\sqrt{s_{NN}}$ = 200 GeV. Strong short and long range correlations (LRC) are seen in central Au+Au collisions. The magnitude of these correlations decrease with decreasing centrality until only short range correlations are observed in peripheral Au+Au collisions. Both the Dual Parton Model (DPM) and the Color Glass Condensate (CGC) predict the existence of the long range correlations. In the DPM the fluctuation in the number of elementary (parton) inelastic collisions produces the LRC. In the CGC longitudinal color flux tubes generate the LRC. The data is in qualitative agreement with the predictions from the DPM and indicates the presence of multiple parton interactions.Comment: 6 pages, 3 figures The abstract has been slightly modifie

Identified baryon and meson distributions at large transverse momenta from Au+Au collisions at sNN=200\sqrt{s_{_{NN}}} = 200 GeV

Transverse momentum spectra of $\pi^{\pm}$, $p$ and $\bar{p}$ up to 12 GeV/c at mid-rapidity in centrality selected Au+Au collisions at $\sqrt{s_{_{NN}}} = 200$ GeV are presented. In central Au+Au collisions, both $\pi^{\pm}$ and $p(\bar{p})$ show significant suppression with respect to binary scaling at $p_T >$ 4 GeV/c. Protons and anti-protons are less suppressed than $\pi^{\pm}$, in the range 1.5 $< p_{T} <$6 GeV/c. The $\pi^-/\pi^+$ and $\bar{p}/p$ ratios show at most a weak $p_T$ dependence and no significant centrality dependence. The $p/\pi$ ratios in central Au+Au collisions approach the values in p+p and d+Au collisions at $p_T >$ 5 GeV/c. The results at high $p_T$ indicate that the partonic sources of $\pi^{\pm}$, $p$ and $\bar{p}$ have similar energy loss when traversing the nuclear medium.Comment: 6 pages, 4 figure