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Large single crystals, as nearly perfect as possible, are required for magnetic resonance studies of the solid state. A limited number of substances occur naturally in crystals of sufficient size or purity for this type of experiment. Most of the nuclear magnetic resonance work done to date on single crystals has been performed using naturally occurring crystals. Section I of this thesis describes methods used to grow suitable crystals artificially, thus extending the scope of the magnetic resonance experiments. The orthorhombic sodium dihydrogen orthophosphate dehydrate has been produced in large single crystals which were used subsequently in the study of the nuclear magnetic resonance absorption spectrum of Na-23 in this crystal. The spectrum was observed as the crystal was rotated about the three crystallographic axes which are mutually perpendicular for the orthorhombic case. A maximum of twelve lines were observed when neither of the crystallographic axes were perpendicular to the external magnetic field. The number of lines was reduced to six when one of the axes was made perpendicular to the field, while only three lines were observed when two crystallographic axes were made perpendicular to the external magnetic field. These observed numbers of lines were interpreted by assuming four Na-23 sites, possessing identical eigenvalues and differing only in their orientation. These four sites are related by three mutually perpendicular two-fold rotation axes, each of which must be parallel to one of the three crystallographic axes. This interpretation is in complete accord with the space group P222 assigned to NaH2PO42H2O from morphological data. The complete set of properties of the quadruple coupling tensor was determined at each of the Na-23 sites. The value of the quadruple coupling constant (eQ Φzz)/h where Q is the nuclear quadruple moment and Φzz is the largest principle value of the electric field gradient tensor is: 1179.0 ± 0.5 kc/sec. The value of the asymmetry parameter η defined as (Φxx – Φyy)/Φzz is: 0.466 ± 0.005. The table of the direction cosines of the principle axes of the electric field gradient tensor with respect to the crystallographic axes appear in Table VII. / Thesis / Master of Science (MSc)

Patients with autonomic dysfunction have benefited from balancing of parasympathetic and sympathetic activity through the practice of slow breathing exercises. In preliminary studies, patients with various autonomic dysfunctions used biofeedback of respiratory activity to slow breathing to a cadence of six cycles per minute, a frequency known as the resonant frequency (Vaschillo, Vaschillo, & Lehrer, 2006). Breathing at this rate produces cardiovascular resonance (large oscillations in heart rate and blood pressure), forcing the autonomic nervous system to continuously regulate these changes, thereby exercising, and eventually strengthening autonomic control over hemodynamic events. The present study examined several methodologies, such as slow breathing exercises, which are believed to strengthen autonomic control by inducing cardiovascular resonance. Specifically, the current experiment compared different methods of inducing cardiovascular resonance, such as paced breathing and biofeedback assisted protocols. The utility of positive emotion inductions to attenuate respiratory discomfort during slow breathing exercises was also examined. Accurate estimation of the resonant frequency using respiratory methods was largely unsuccessful. However, all respiratory methods produced profound effects in the cardiovascular system, with some differences in the magnitude of effect. In addition, the utility of an emotion induction during slow paced breathing was also demonstrated. The results of this study also support the notion that slow breathing improves pulmonary gas exchange efficiency, in addition to strengthening the baroreflex, by increasing heart rate variability. / Master of Science