Thesis (M.S.)--University of Nevada, Reno, 2006. / "May, 2006." Includes bibliographical references (leaves 44-48). Online version available on the World Wide Web.

Thesis (Ph.D.)--York University, 2008. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 123-130). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR45983

The present study combines modern jet reconstruction algorithms and particle identification (PID) techniques in order to study the enhancement of proton/pion ratio at mid transverse momentum ([mathematical symbols] 1.5 - 4.0 GeV/c) observed in central Au + Au collisions at [mathematical symbols] = 200 GeV. The ratio enhancement is thought to be caused by recombination processes and/or parton fragmentation modification of jets in relativistic heavy ion collisions. The fragmentation modification hypothesis is tested in this analysis by reconstructing and selecting energetic jets presumably biased to fragment outside of the medium created in Au + Au collisions and comparing their particle composition to the recoiling (medium-traversing) jets. The bias assumption is confirmed by comparing jets in central collisions, where the effect of proton/pion enhancement is present, with peripheral ones where no medium effects are expected. The selected jets are reconstructed by using the anti-k[subscript T] algorithm from the modern FASTJET package. The PID in the p[subscript T] region of interest is possible by combining measurements of the particles' energy deposition and velocity from the Time Projection Chamber and the recently installed (2009-2010) Time of Flight detectors at STAR. The acceptance of these detectors, [eta] < 1.0 and full azimuth, make them extraordinary tools for correlation studies. These features allow for the measurement of relative azimuth ([phi] [subscript jet] - [phi] [subscript pion,proton]) distributions by using the selected jet axis in order to disentangle the uncorrelated background present in the high multiplicity heavy ion collisions. The proton/pion ratios in two different centrality bins and p[subscript T] = 1.2 - 3.0 GeV/c are presented for biased (vacuum fragmenting) jets and their recoiling counterparts / text

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The competition between two molecules of similar polarity for adsorption sites on the stationary phase is discussed in light of rapid kinetics of adsorption and desorption, and of the effects of temperature, acetonitrile, surfactant (cyclohexylaminopropane sulfonic acid, CAPS) and salt concentrations on the retention of the thyroid hormones (3,5-diiodothyronine, T2; 3,3',5-triiodothyronine, T3 and thyroxine, T4). A three parameter equation relates the surfactant concentration and ionic strength to the retention of the hormones and is analyzed in terms of the Stern-Gouy-Chapman theory. A second order polynomial describes the temperature dependency and permits the evaluation of the enthalpy, entropy and heat capacity, demonstrating a reduction in the molecular motion of the analyte with increasing surfactant and acetonitrile concentrations. The equation parameters for linear or non-linear equations, using data sets with or without homogeneous variances, are evaluated using a Simplex optimization procedure that uses one of two proposed optimization criteria. The construction and operation of a computer based gradient programmer for HPLC is described. A surfactant mediated gradient elution with electrochemical detection is examined for the analysis of serum thyroid hormones.

In this dissertation, the phenomenology of electromagnetic radiation and high transverse momentum jets in relativistic heavy ion collisions is investigated. These are two very important probes to study the strongly interacting matter at extreme temperatures and/or densities and to investigate the possibility of a phase transition between hadronic matter and quark-gluon plasma (QGP). First, a new channel of direct photon production from a charge-asymmetric QGP is explored in the effective theory of quantum chromodynamics (QCD) at high temperature. The photon production from this new channel is found to be suppressed compared to QCD annihilation process and Compton scattering at low baryon density, but might assume significance in baryon-rich matter. Second, the radiative jet energy loss in a three-dimensional ideal hydrodynamical medium is studied for Au+Au collisions at Relativistic Heavy Ion Collider (RHIC). A systematic analysis of the nuclear modification factor RAA is presented for pi0 production at high pT in central and non-central collisions, at mid and forward rapidity. Third, jet energy loss by elastic collisions is consistently incorporated in the same formalism and applied to the study of jet quenching at RHIC. It is found that the nuclear modification factor RAA for pi0 in relativistic heavy ion collisions is sensitive to both collisional and radiative energy loss, while the average energy loss is less affected by the inclusion of collisional energy loss. Last, the nuclear suppression of photon-tagged jets at high pT is studied by incorporating not only direct photons, but the additional sources from fragmentation and jet-plasma interaction. We find that these additional sources are very important for a complete study of the correlations between hard photons and hadrons and even dominate in some kinetic regime.

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