Thesis (M. Phil.)--University of Hong Kong, 1981.

published_or_final_version / Chemistry / Master / Master of Philosophy

The role of the hypothalamic paraventricular nucleus (PVN) in cardiovascular and neuroendocrine regulation has been well documented. Much remains unknown however about the integration of synaptic signals within this nucleus and the neuronal subtypes and chemical messengers governing these processes. Angiotensin II (ANG) has been demonstrated to act as a neurotransmitter in PVN where it exerts considerable influence on neuronal excitability. The studies within this thesis were undertaken to delineate the actions of ANG on the membrane properties of PVN neurons and its effect on synaptic transmission within this nucleus. We report that ANG activates a nitric oxide mediated negative feedback loop in the PVN. The magnitude of the depolarizing response to ANG appears to be dependant on this GABAergic inhibitory input demonstrating there exists within PVN an intrinsic negative feedback loop which modulates neuronal excitability in response to peptidergic excitation. We also demonstrate that the depolarizing response to ANG in magnocellular neurons is in part dependent upon increases in glutamatergic excitatory synaptic input. These data in combination highlight the multiple levels of synaptic integration controlling the output of magnocellular neurons in PVN. PVN also contains significant populations of neurosecretory parvocellular neurons which exercise considerable influence over the adenohypophysis and therefore neuroendocrine regulation. ANG caused an AT1 receptor mediated depolarization of these neurosecretory neurons. Voltage-clamp analysis revealed that ANG activated a non-selective cationic current and reduced a sustained potassium current characteristic of IK. These studies identify multiple post-synaptic modulatory sites through which ANG can influence the excitability of neurosecretory parvocellular PVN neurons. The findings in this thesis provide the framework for a cellular model of action of ANG within PVN to regulate the activity of this nucleus not only through direct cellular mediated ion channel interactions but also through modulation of synaptic input within the magnocellular system of PVN. / Thesis (Ph.D, Physiology) -- Queen's University, 2008-01-18 14:10:22.319

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Objective: To determine the magnitude of the skeletal and dental movements in subjects with different facial patterns following Class II correction using the XbowTM appliance. Materials and Methods: A retrospective sample of 134 subjects exhibiting Class II malocclusions was used. Subjects were categorized into three growth types according to pre-treatment cephalometric variables (MPA and Y-axis), which yielded 27 brachycephalic, 70 mesocephalic, and 37 dolichocephalic subjects. A ANOVA test statistic was used to investigate the differences between the three facial groups at pre and post-treatment time points. Results: Dental changes induced by the XbowTM appliance included: proclination of the lower incisors (L1-MP 7.3-12.3o±1.0o), protrusion of the lower incisors (L1-APo 2.1-3.8mm±0.3mm), mesial movement of the mandibular first molar (5.5-6.9mm±0.7mm) and retrusion of the maxillary incisor (2.4-3.1mm±0.4mm). Retroclination of the maxillary incisor (U1-PP 0.2-0.8o±0.7o) and distal movement of the maxillary molar (0.4-0.7mm±0.3mm) were not significantly influenced by XbowTM treatment. Reduction of the skeletal Class II relationship was represented by a significant decrease of the Wits value (2.4-4.5mm±0.5mm) in all three groups. The p value was considered significant at <0.05. Conclusions: Class II correction with the XbowTM appliance is the result of mesial movement of the mandibular molar, proclination/protrusion of the lower incisor and retrusion of the upper incisor. Skeletal correction must be validated by more than one cephalometric variable. Facial growth pattern appears to be unrelated to the amount of dental movement and there is a trend for pronounced dental movements of the lower incisor in brachycephalic patients.

Surface downward far-infrared (far-IR) spectra were collected from NASA’s Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument from August to October 2009 at an altitude of 5.4 km near the summit of Cerro Toco, Chile. This region is known for its dry, cold, and dominantly clear atmosphere, which is optimal for studying the effects, that water vapor and cirrus clouds have on the far-IR. Comparisons with Line-By-Line Discrete Ordinants Radiative Transfer model, LBLDIS, show that FIRST observes the very fine spectral structure in the far-IR with differences as small as +/- 0.7% for both clear-sky and cloudy-sky simulations. Clear sky model analysis demonstrated the greatest sensitivity to atmospheric conditions is between 300 and 500 cm-1. The cloudy-sky simulations demonstrated that the far-IR radiation has minimal sensitivity to cloud particle effective radius, yet is very sensitive to cloud optical thickness at wavenumbers between 400 - 600 cm-1. In fact, cirrus optical thickness found to be inferred from the brightness temperature differences at 250 and 559.5 cm-1. Aerosols proved to reduce downwelling radiance by half that a clear-sky would emit, but had little effect on the total far-IR radiative forcing. Furthermore, these far-IR measurements open a new window to understanding the radiative impacts of various atmospheric constituents such as water vapor and clouds, and to understanding and modeling the Earth’s climate and energy budget.

Objective: To determine the magnitude of the skeletal and dental movements in subjects with different facial patterns following Class II correction using the XbowTM appliance. Materials and Methods: A retrospective sample of 134 subjects exhibiting Class II malocclusions was used. Subjects were categorized into three growth types according to pre-treatment cephalometric variables (MPA and Y-axis), which yielded 27 brachycephalic, 70 mesocephalic, and 37 dolichocephalic subjects. A ANOVA test statistic was used to investigate the differences between the three facial groups at pre and post-treatment time points. Results: Dental changes induced by the XbowTM appliance included: proclination of the lower incisors (L1-MP 7.3-12.3o±1.0o), protrusion of the lower incisors (L1-APo 2.1-3.8mm±0.3mm), mesial movement of the mandibular first molar (5.5-6.9mm±0.7mm) and retrusion of the maxillary incisor (2.4-3.1mm±0.4mm). Retroclination of the maxillary incisor (U1-PP 0.2-0.8o±0.7o) and distal movement of the maxillary molar (0.4-0.7mm±0.3mm) were not significantly influenced by XbowTM treatment. Reduction of the skeletal Class II relationship was represented by a significant decrease of the Wits value (2.4-4.5mm±0.5mm) in all three groups. The p value was considered significant at <0.05. Conclusions: Class II correction with the XbowTM appliance is the result of mesial movement of the mandibular molar, proclination/protrusion of the lower incisor and retrusion of the upper incisor. Skeletal correction must be validated by more than one cephalometric variable. Facial growth pattern appears to be unrelated to the amount of dental movement and there is a trend for pronounced dental movements of the lower incisor in brachycephalic patients.

The impact of two constitutional isomers, 2-(4-BMes2-Ph)-pyridine (p-B-ppy) and 5-BMes2-2-ph-pyridine (p-ppy-B), as N,C-chelate ligands on the structures, stabilities, electronic and photophysical properties, and Lewis acidities of Pt(II) complexes has been investigated. Six Pt(II) complexes, Pt(p-B-ppy)Ph(DMSO), Pt(p-B-ppy)Ph(Py), [Pt(p-B-ppy)Ph]2(4,4’-bipy), Pt(p-ppy-B)Ph(DMSO), Pt(p-ppy-B)Ph(Py), and [Pt(p-ppy-B)Ph]2(4,4’-bipy), have been synthesized and fully characterized. The Lewis acidity of the complexes was examined by fluoride titration experiments using UV-Vis, phosphorescence, and NMR spectroscopic methods, establishing that the p-ppy-B complexes have stronger binding constants while the p-B-ppy complexes have a much lower affinity toward F-. A diboron compound with both 3-coordinate boron and 4-coordinate boron centers, (5-BMes2-2-ph-py)BMes2 (B2ppy) has been synthesized, which is luminescent but have a high sensitivity toward light. UV and ambient light cause this compound to isomerize via the formation of a C−C bond between a mesityl and the phenyl group, accompanied by a drastic color change from yellow to dark olive green. The structure of the dark color species was established by 2D NMR experiments and geometry optimization by DFT calculations. The dark color species can thermally reverse back to (5-BMes2-2-ph-py)BMes2 via the breaking of a C−C bond. The N, C-chelate ligand was found to play a key role in promoting this unusual and reversible photo–thermal isomerization process on a tetrahedral boron center. The impact of Pt(II) on the photoisomeration of four-coordinate boron center was also studied. The free ligand four-coordinate organoboron derivative B-ppy-ppy behaved in the same way as B2ppy. The photoisomeration process in the corresponding Pt(II) coupled complex (B-ppy-ppy)PtPh(t-Bu-py) is nearly completely deactivated, which may be attributed to either the low-lying 3MLCT excited state through which the excess energy in excited state was dissipated as phosphorescence or the greater π conjugation which can stabilize the excited state. / Thesis (Master, Chemistry) -- Queen's University, 2009-09-24 14:56:32.845

Conventional interpretations regarding the role of the Political Warfare Executive during the Second World War have concentrated almost exclusively on the propaganda output of the organisation. The role of the intelligence sections working for and within the organisation have been largely disregarded or overlooked in the existing history of Executive. This thesis offers a re-evaluation of the PWE which includes this `missing dimension', specifically here the intelligence work of the German Section of the Executive. This approach widens the scope of enquiry to include an exploration of the links between intelligence and propaganda, subversion and sabotage and considers the importance of this relationship for the way in which the PWE emerged. The examination of the Weekly Reports of the German Section identifies a different `type' of intelligence which can be described as `social political' intelligence, which provided the British government with a unique view of the social and political conditions in Germany throughout the duration of the war. The thesis concentrates on the period after the announcement of Unconditional Surrender in January 1943 to the early months on 1946, when the personnel and expertise of the German Section were transferred to the Foreign Office. The analysis of the intelligence reports of the German Section is focussed on three particular issues of interest to government at the time and to historians today. These are German resistance and public opinion, British occupational rule, and the emergence of the perception of the Russian `threat' in Whitehall which signalled the beginning of the Cold War. Taken together these illustrate the way in which the PWE incrementally expanded it's activities over this period of time, and provide the basis for the re- evaluation of the Executive.