The formation of grain boundary precipitates of the high temperature β phase from the supersaturated ɤ phase has been examined in Ag-5.64 wt.% aluminum alloys at 688°C . Large grained samples were used and the boundary misorientations were determined by X-ray diffraction. At low angle boundaries only primary sideplates formed while above a misorientation of 17° lenticular precipitates were dominant. Precipitate growth was studied on individual grain boundaries using a statistical technique. The lengthening and thickening rates were independent of the grain boundary misorientation indicating that grain boundary diffusion was not significant under these conditions. The precipitates grew with constant shape, with both the length and thickness increasing parabolically with time. By approximating the shape of the precipitate to that of an oblate spheroid growing with constant shape, an equivalent diffusion coefficient was calculated. The value obtained was in good agreement with measurements obtained from diffusion couples. The nature of the quenched β phase was also examined using optical and electron microscopy. The βphase transformed rapidly on cooling, forming a massive [symbol omitted] product or an acicular martensite at higher quenching rates. The structures were very similar to those reported for the Cu-Ga and Cu-Al systems. Many grain boundary precipitates showed unequal growth into the two matrix grains. Measurements of the matrix habit plane suggested that a possible orientation relationship existed between the precipitate and that grain into which no development occurred. In this case the precipitate nucleated in one grain but grew into the opposite grain. Precipitates which developed equally into both grains exhibited no apparent habit relationship with either grain. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

In this work the problematic issue of price determination in economic theory is re-examined. In the first chapter a state-of-the-art survey regarding the existence of equilibrium and the structure of the equilibrium set in price-setting games is provided. In chapter two a new core concept, the Bertrand core, is introduced and characterized. In chapter three a revealed preference perspective upon the Nash equilibria in price-setting games is provided. In chapter four, the issue of Bayesian equilibrium existence is addressed when traders have incomplete information regarding each others' types. Finally, a summary of possible future avenues for research in this area is provided.

It is known that quantum strategies change the range of possible payoffs for the players in the prisoner's dilemma. In this paper, we examine the effect of the degree of entanglement in determining the payoffs. When both players play quantum strategies, we show that the payoff for both players is unaffected by the entanglement value and it leads to a new Nash equilibrium.

Values of thermodynamic stability constants at 25°C for the complexes of serine with the metal ions. Co^2+, Ni^2+, Cd^2+, Zn^2+, and Cu^2+ were obtained from pH titration data. All measurements were made in aqueous solution, and data were obtained at three different ionic strengths for each metal ion studied. It was assumed that the activity of the zwitterion is unity. The effect of metal ion hydrolysis upon the log K values was taken into account for the calculations. For all the metal ions studied, stability constants for MA^+, MA_2, and MA_3^- were reported with the exception of copper (II) which formed only MA^+ and MA_2 complexes. The stabilities of the complexes studied follow the sequence: Cd^2+ < Co^2+ < Zn^2+ < Ni^2+ < Cu^2+. The value of log K for each step of metal serine interaction, in all cases, increases in the order. K_3 < K_2 < K_1. Under the conditions studied, it was assumed that the metal ion coordinates through the amino nitrogen and the carboxyl oxygen of the serine only. There was no evidence that the hydroxyl group of serine took part in coordination with the metal ions. All calculations of stability constants were carried out using an IBM 7040 computer.

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Hepatocyte transmembrane potential (V(m)) during osmotic stress responds as an osmometer, in part because of changes in membrane K+ conductance. This may contribute to the electromotive force that drives transmembrane Cl- fluxes. To test this, double-barreled ion-sensitive microelectrodes were used to measure changes in steady-state intracellular Cl- activity (a(Cl)/(i)) during osmotic stress applied to mouse liver slices. Hyperosmotic and hyposmotic conditions were created by rapidly switching to a solution in which sucrose concentrations were increased or reduced, respectively. Hyperosmotic stress [1.4 x control osmolality (280 mosmol/kgH2O)] decreased hepatocyte V(m) 46% from -39 ± 1 to -21 ± 1 mV (SE; n = 16 animals). Corresponding a(Cl)/(i) increased twofold from 19 ± 2 to 38 ± 3 mM. This shifted the Cl- equilibrium potential (E(Cl)) 19 mV, from -38 ± 0.3 to -19 ± 2 mV. Hyposmotic stress [0.71 x control osmolality (290 mosmol/kgH2O)] increased hepatocyte V(m) 64% from -28 ± 1 to -46 ± 1 mV (SE; n = 13 animals). Corresponding a(Cl)/(i) decreased 0.53-fold from 17 ± 1 to 8 ± 1 mM. This shifted the E(Cl) 20 mV from -26 ± 2 to -46 ± 3 mV. Thus hepatocyte a(Cl)/(i) is in electrochemical equilibrium with V(m). The paired measurements above were repeated after addition of K+-channel blockers quinine or Ba2+. Ba2+ (2 mM) had no effect on either V(m) or a(Cl)/(i) during hyperosmotic stress; however, Ba2+ significantly inhibited changes in V(m) and a(Cl)/(i) during hyposmotic stress. Effects of quinine (0.5 mM) on V(m) and a(Cl)/(i) during both hyperosmotic stress and hyposmotic stress were similar to those of Ba2+. A previous report shows that inhibition of hyposmotic stress-induced V(m) changes results in loss of hepatocyte volume regulation and greater swelling. Thus osmotic stress-induced changes in a(Cl)/(i) are nowhere near those predicted by cell water volume changes based on transmembrane osmotic pressure differences. We conclude that these larger changes in a(Cl)/(i) resulted from voltage-driven transmembrane Cl- fluxes.

<p> Several concepts have been developed recently in the intraurban mobility literature. Among them the concepts of aspirations, place utility and stress are of particular importance. Nevertheless, their definition appears to be not very clear.</p> <p> This paper aims to clarify them by employing concepts from the consumer choice theory as they are used in equilibrium models in Geography. With this purpose in mind the world of a specific equilibrium model is used. The distinction between the hypothetical world of this model and the real world is continuously emphasized.</p> <p> In order to clarify further the concepts mentioned above a particular example is given. In this example a Cobb-Douglas is used as a utility function.</p> / Thesis / Master of Arts (MA)

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