A novel imaging modality is introduced, using Radio-Frequency Longitudinally Detected Electron Spin Resonance (RF-LODESR), capable of providing qualitative and semi-quantitative information on a variety of parameters reflecting physiological function, the most significant being tissue oxygenation. Effective spin-lattice (T_1e*) and spin-spin (T_2e*) electronic relaxation time maps of the abdomen of living 200 g rats were generated after intravenous administration of a triarylmethyl free radical (TAM). These maps were used to evaluate oxygen distribution. Differences between the liver, kidneys and bladder were noted. Conclusions were made regarding distribution, perfusion and excretion rate of the contrast medium. Ligature induced anoxia in the kidney was also visualised. LODESR involves transverse ESR irradiation with a modulated excitation and observing oscillations in the spin magnetisation parallel to the main magnetic field. The T_1e* and T_2e* maps were calculated from a set of LODESR signal phase images collected at different detection frequencies. Each phase image also provides qualitative information on tissue oxygen level without any further processing. Additionally, a new method is introduced for measuring T_1e, valid for inhomogeneous spectra, based on measuring the spectral area as a function of detection frequency. These methods present alternatives to the conventional transverse ESR linewidth-based oximetry methods, particularly for animal whole body imaging applications.

Baryons are considered in the Nonrelativistic Quark Model (NQM) to be bound states of three valence quarks. Each quark has two possible spin eigenstates in the restframe of the baryon whose spin is fully carried by quarks. The baryon wavefunctions are connected through SU(6) symmetry rotations. For a long time, the measured magnetic moments of the baryons appeared to be in agreement with the NQM predictions. However, recent experiments which are examining the spin structure of the baryons show the failure of several NQM predictions. The so-called 'spin crisis' arose from the interpretation of the EMC deep inelastic scattering measurement of ∫ g^p₁ that the quark spins in the proton appeared to sum up to (almost) zero. In this thesis it will be demonstrated that the spin problem is not a phenomenon restricted to quasi-massless current quarks in the high energy limit. Symmetry arguments are used to examine the baryon magnetic moments and reveal that we can observe massive but pointhke constituent quarks, with a characteristic mass ratio m_u = m_d ≃ ²andfrasl;₃m_s. Surprisingly they do not contribute much to the baryon spin either. This analysis is free of the ambiguity arising from the UA(1} gluon anomaly which makes it impossible to calculate precisely the spin sum of the current quarks. One important finding in our analysis is the observation that the effects of SU(6) breaking hyperfine spin-spin interactions (which cause well-known splittings in the baryon masses) can be seen in the environment dependence of the constituent quark masses. The effective mass of a quark cannot be independent of its surrounding energy since the mass of the baryon is distributed amongst its constituents. Consistent with the hypothesis that different quark masses do not impose SU(3) breaking on the baryon wavefunctions is the observation of induced 'second class' form factors. The way in which SU(3) breaking alters the ^g_Aandfrasl;_{g_V} ratios in semileptonic hyperon decays will be discussed and strong evidence for a new value of F/D is given, which is close to its SU(6) value. This value is derived independently from the baryon β-decays <strong>and</strong> from their magnetic moments. Dynamical models are discussed which might explain the observed polarised strangeness 'inside' the proton, and the almost vanishing quark spin sum.

Zugl.: Berlin, Freie Univ., Diss., 2007

Thesis (Ph.D.)--Virginia Commonwealth University, 2008. / Prepared for: Dept. of Electrical Engineering. Title from thesis description page. Includes bibliographical references.

Zugl.: Berlin, Freie Univ., Diss., 2007

Zugl.: Kiel, Universiẗat, Diss., 2007.

Zugl.: Kiel, Univ., Diss., 2007

Würzburg, Univ., Diss., 2008

Thesis (Ph. D. in Physics)--University of California, Berkeley, March 1960. / TID-4500 (15th ed.). Includes bibliographical references (p. 112-115).

Thesis (Ph.D.)--University of California, Berkeley, 1961. / "UC-34 Physics" -t.p. "TID-4500 (16th Ed.)" -t.p. Includes bibliographical references (p. 111-114).