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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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This thesis describes the experimental study of electron scattering processes from laser-excited barium and ytterbium atoms. These include the electron-impact ionization-excitation from Ba (...6s6p) 1P1 and Ba (...6s5d) 1,3D1,2 to Ba+ (...6p) 2P3/2, the elastic electron scattering from Ba (...6s6p) 1P1 and Ba (...6s5d) 1,3D1,2, and the electron-impact excitation from Yb (...6s6p) 3P1 to Yb (...6s7s) 3S1, Yb (...6s6p) 1P1, and Yb (...6s5d) 3D1,2,3. The experiments utilized electron impact energies in the range of 5 eV to 50 eV. Differential and integral scattering cross sections were determined, and are presented both on absolute and relative scales. By controlling the laser polarization, alignment and orientation parameters characterizing the scattering processes were determined. Additionally, the barium ionization-excitation study observed polarization dependencies of ion line emission fluorescence for radiative decay from Ba+ (...6p) 2P3/2 to Ba+ (...6s) 2S1/2, providing information about the final ionic state composition. Along with experimental measurements of electron-atom collisions, this thesis describes the design and development of a computer-controlled data acquisition system and a laser frequency stabilization system.

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I present the measurements, analysis and results obtained with the NA34 experiment at the CERN European laboratory, on the global characteristics of particle production in ultra-relativistic oxygen-nucleus collisions, at incident energies of 60 and 200 GeV/nucleon. The observed properties of the particle flow are analysed in the framework of phenomenological models inspired by quantum chromodynamics. From this analysis, novel information emerges concerning the mechanisms and space-time evolution of the soft-hadronic processes in short-lived extended volumes of matter at extreme densities and temperature. We consequently study the parameters and critical conditions under which nuclear collisions could allow the observation of a phase transition from hadronic matter towards a new state of deconfined quark-gluon plasma matter.