A new technique, named Vertical Profile Indicator (VPI), which uses the vertical structure of the reflectivity profile to delineate regions most likely to have supercooled liquid water content (SCLWC) within the precipitation field, was developed. When the aircraft flew in the "active regions" (as defined by the VPI technique) it was found that 90% of the time significant amounts of SCLWC were observed. / Using Doppler and "Quasi-Doppler" radar data, high convergence cores (> 3.0 x 10('-3) s('-1)) and updraft activity were observed to occur preferentially in the "active regions". During the 1981 winter-spring period of the Precipitation Enhancement Project in the Duero Basin of Spain percentages of "active regions" in relation to the whole precipitation field, and in relation to the total radar observation area, did not exceed 47% and 18% respectively. / The VPI technique provides information which may be used to direct research aircraft to cloud regions containing SCLWC to allow measurements of the time evolution of their microphysical state. These measurements would permit a better estimation of the residence time of the SCLWC and its removal rates. This is a key parameter for better understanding the microphysical properties of clouds and consequently the possibility of artificial modification of precipitation.

Doctor of Philosophy (PhD) / The glass-transition traverses continuously from liquid to solid behaviour, yet the role of structure in this large and gradual dynamic transition is poorly understood. This thesis presents a theoretical study of the relationship between structure and dynamics in two-dimensional glass-forming alloys, and provides new tools and real-space insight into the relationship at a microscopic level. The work is divided into two parts. Part I is concerned with the role of structure in the appearance of spatially heterogeneous dynamics in a supercooled glass-forming liquid. The isoconfigurational ensemble method is introduced as a general tool for analysing the effect that a configuration has on the subsequent particle motion, and the dynamic propensity is presented as the aspect of structural relaxation that can be directly related to microscopic variations in the structure. As the temperature is reduced, the spatial distribution of dynamic propensity becomes increasingly heterogeneous. This provides the first direct evidence that the development of spatially heterogeneous dynamics in a fragile glass-former is related to spatial variations in the structure. The individual particle motion also changes from Gaussian to non- Gaussian as the temperature is reduced, i.e. the configuration expresses its character more and more intermittently. The ability of several common measures of structure and a measure of structural ‘looseness’ to predict the spatial distribution of dynamic propensity are then tested. While the local coordination environment, local potential energy, and local free volume show some correlation with propensity, they are unable to predict its spatial variation. Simple coarse-graining does not help either. These results cast doubt on the microscopic basis of theories of the glass transition that are based purely on concepts of free volume or local potential energy. In sharp contrast, a dynamic measure of structural ‘looseness’ - an isoconfigurational single-particle Debye-Waller (DW) factor - is able to predict the spatial distribution of propensity in the supercooled liquid. This provides the first microscopic evidence for previous correlations found between short- and long-time dynamics in supercooled liquids. The spatial distribution of the DW factor changes rapidly in the supercooled liquid and suggests a picture of structural relaxation that is inconsistent with simple defect diffusion. Overall, the work presented in Part I provides a real-space description of the transition from structure-independent to structure-dependent dynamics, that is complementary to the configuration-space description provided by the energy landscape picture of the glass transition. In Part II, an investigation is presented into the effect of varying the interparticle potential on the phase behaviour of the binary soft-disc model. This represents a different approach to studying the role of structure in glass-formation, and suggests many interesting directions for future work. The structural and dynamic properties of six different systems are characterised, and some comparisons are made between them. A wide range of alloy-like structures are formed, including substitutionally ordered crystals, amorphous solids, and multiphase materials. Approximate phase diagrams show that glass-formation generally occurs between competing higher symmetry structures. This work identifies two new glass-forming systems with effective chemical ordering and substantially different short- and medium-range structure compared to the glassformer studied in Part I. These represent ideal candidates for extending the study presented in Part I. There also appears to be a close connection between quasicrystal and glass-formation in 2D via random-tiling like structures. This may help explain the experimental observation that quasicrystals sometimes vitrify on heating. The alignment of asymmetric unit cells is found to be the rate-limiting step in the crystal nucleation and growth of a substitutionally ordered crystal, and another system shows amorphous-crystal coexistence and appears highly stable to complete phase separation. The generality of these results and their implications for theoretical descriptions of the glass transition are also discussed.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 48-52). Also available in electronic version.

Thesis (M.App.Sc.) - Carleton University, 2001. / Includes bibliographical references (p. 80-83). Also available in electronic format on the Internet.

Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 97-98). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references and index.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 342-347). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.)--University of Western Australia, 2007.

Thesis (M.S. in Chemical Engineering)--University of California, Berkeley, June 1955. / "Unclassified Chemistry." Errata sheet at end. Includes bibliographical references (p. 88). 12

Thesis (Ph.D.)--McMaster University, 2003. / Advisor: R. L. Judd. Includes bibliographical references (leaves 253-256). Also available via World Wide Web.