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No description available.

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No description available.

Oestrogen receptors (ER) have classically been described as ligand-inducible nuclear transcription factors. The pleiotrophic effects of ER function have a predominant role in the direct regulation of the growth, differentiation and development of tissues of the human reproductive system. There are two ER subtypes, ER and ER which differ in their specificity for ligand and the consequent actions they orchestrate. Moreover, the latter exists in multiple splice variants of which ER is the only fully functional homologue. Research into the underlying differences in subtype responses to ligand has involved examination of the intranuclear dynamics of individual receptor subtypes. Studies into the mobility of ER in response to ligand have exclusively focused on studies of full length ER and ER independently in transfected cell lines. The studies described in this thesis have investigated the kinetics of ER using Fluorescence Recovery After Photobleaching (FRAP) in infected cell lines which lends itself to more precise expression of the subtype of interest. The morphological impact of natural oestrogenic and synthetic ligands on ERs was examined and the influence on the intranuclear dynamics assessed. Further to this, the effect of co-expression of different ER subtype combinations was examined. Studies on the intranuclear mobility of ER have confirmed and extended the findings of others. Previous work on the development of ER agonists and antagonists has been to target specific overexpressing ER subtypes in a physiological setting. In this study, we demonstrated for the first time an overwhelming ER -selective effect in slowing the rate of mobility within the nucleus, suggesting the study of intranuclear dynamics is an important parameter for the examination of efficacy of a compound. Differential responses to ligand based on co-infected partnerships indicate that heterodimerisation has a profound effect in augmenting ligand-dependent regulation and activity.

We start by analysing the effect of random perturbations on non-hyperbolic scattering dynamics.  We show that, under small random fluctuations of the field, trajectories starting inside KAM islands, not only escape but also gain hyperbolic-like time decay.  We show a random walk modelling this distribution to the amplitude of noise, what is expected to be a universal quadratic power law.  Due to the effect of the random perturbations, we show that the typical dimension of invariant sets is that which is obtained for hyperbolic dynamics. For dissipative systems, we show that when the dissipation is decreased, the number of periodic attractors increase.  Furthermore, we show that the dynamics is then better described by invariants that are time and length scale dependent. Employing random maps we described the escape of a random orbit from an attractor in terms of a dynamical system with a chosen “hole”. We show that the mean escape time depends on the measure of this hole, and we analytically obtain one universal power law describing such dependence.  Once we have described the escape from one attractor, we tackle dynamics of a system having finitely many coexisting attractors in terms of conditional invariant measures.  We study conditions for the hopping process to happen and the sojourn time distribution, according to hyperbolic properties. In the second part of this thesis, we study random dynamical systems from a mathematical perspective. Using set dynamic, we prove the existence of a finite number of random attractors.

This thesis explores the role of terrestrial vegetation in the global climate system in a series of modelling studies using the University of Victoria Earth System Climate Model (UVic ESCM). The ways that vegetation affects climate, as well as the feedbacks that operate between changing climate and vegetation distributions, are investigated within the framework of three foci: 1) historical land cover changes that have resulted from human modification of natural vegetation cover; 2) historical land cover change and the dynamics of terrestrial vegetation in the context of anthropogenic and natural climate change; and 3) the role of terrestrial vegetation in the global carbon cycle. First, the radiative effect of changing human land-use patterns on the climate of the past 300 years is discussed through analysis of a series of equilibrium and transient climate simulations using the UVic ESCM. These experiments highlight the biogeophysical effects of historical land cover change on climate: those that result from physical changes to the land surface under altered vegetation cover. Results show a global cooling in the range of -0.06 to -0.22 "C, though this effect is not found to be detectable in observed temperature trends. Using a global carbon cycle the climatic effects of land cover change emissions (the biogeochemical effect of historical land cover change) are assessed. The resultant warming is found to exceed the biogeophysical cooling by 0.15 "C. Second, the effect of historical land cover change is compared with the effects of natural forcings (volcanic aerosols, solar insolation variability and orbital changes) and other anthropogenic forcings (greenhouse gases and sulphate aerosols). Transient model runs from the year 1700 to 2000 are presented for each forcing individually as well as for combinations of forcings. I find that the UVic model reproduces well the global temperature data when all forcings are included. In the context of these anthropogenic and natural climate influences, the response of vegetation distributions to changing climate is explored through the use of a dynamic global vegetation model coupled interactively to the UVic ESCM. Transient simulations of the past 300 years are repeated using this new model so as to isolate the biogeophysical feedbacks that operate between vegetation and climate. Dynamic vegetation is found to act as a positive feedback to climate, amplifying both warming and cooling climate trends. Third, the development of a global carbon cycle model allows for investigation of the role of terrestrial carbon cycle dynamics under past and future climate change. When forced by historical emissions of C02 from fossil fuels and land-use change, the coupled carbon cycle model accurately reproduces historical atmospheric C02 trends, as well as terrestrial and oceanic uptake for the past two decades. Under six 21St century C02 emissions scenarios, both terrestrial and oceanic carbon sinks continue to increase, though terrestrial uptake slows in the latter half of the century. The modelled positive feedback between the carbon cycle and climate is relatively small, resulting in an increase in simulated C02 of 60 ppmv at the year 2100. Including non- C02 greenhouse gas forcing and increasing the model's climate sensitivity increases the effect of this feedback to 140 ppmv. The UVic model does not, however, simulate a switch from a terrestrial carbon sink to a source during the 2lSt century, as earlier studies have suggested. This can be explained by a lack of substantial reductions in simulated vegetation productivity due to climate changes.

The Boltzmann equation is the basic equation to describe rarefied gas flows. Some kinetic models with simple expressions for the collision term have been proposed to reduce the mathematical complexity of the Boltzmann equation. All macroscopic continuum equations can be derived from the Boltzmann equation or kinetic models through the Chapman-Enskog method, Grad's moment method, etc. This thesis is divided into three parts. In the first part, existing kinetic models (BGK model, ES-BGK model, v(C) -BGK model, S model, and Liu model), and two newly proposed v(C)-ES-BGK type kinetic models are described and compared, based on properties that need to be satisfied for a kinetic model. In the new models a meaningful expression for the collision frequency is used, while the important properties for a kinetic model are retained at the same time. In the second part of this work, the kinetic models (BGK, ES-BGK, v(C) -BGK, and two new kinetic models) are tested numerically for one-dimensional shock waves and one-dimensional Couette flow. The numerical scheme used here is based on Mieussens's discrete velocity model (DVM). Computational results from the kinetic models are compared to results obtained from the Direct Simulation Monte Carlo method (DSMC). It is found that for hard sphere molecules the results obtained from the two new kinetic models are very similar, and located in between the results from the ES-BGK and the v(C)-BGK models, while for Maxwell molecules the two new kinetic models are identical to the ES-BGK model. For one-dimensional shock waves, results from the new kinetic model II fit best with results from DSMC; while for one-dimensional Couette flow, the ES-BGK model is suggested. Also in the second part of the work, a modified numerical scheme is developed from Mieussens's original DVM. The basic idea is to use a linearized expression of the reference distribution function, instead of its exact expression, in the numerical scheme. Results from the modified scheme are very similar to the results from the original scheme for almost all done tests, while 20-40 percent of the computational time can be saved. In the third part, several sets of macroscopic continuum equations are examined for one-dimensional steady state Couette flow. For not too large Knudsen numbers (Knc=O.l) in the transition regime, it is found that the original and slightly linearized regularized 13 moment equations give better results than Grad's original 13 moment equations, which, however, give better results than the Burnett equations, while the Navier-Stokes-Fourier equations give the worst results, which is in agreement with the expectation. For large Knudsen number situations (Kn>O.l), it turns out that all macroscopic continuum equations tested fail in the accurate description of flows, while the Grad's 13 moment equations can still give better results than the Burnett equations.

Identifying the influence of eastern boundary current (EBC) dynamical processes on sound speed structure can provide better ocean models for acoustic predictions in littoral regions. This study will explore the effects of currents, wind and eddies on the sound speed structure of two different EBC models, the North Canary Current System (NCCS) and the Leeuwin Current System (LCS). These systems represent classical features of EBCs as well as regional anomalies. This study seeks to introduce sound speed analysis to the sigma coordinate primitive equation models and determine which regions of EBCs experience the largest changes in sound speed and most intense gradients. Results of model runs show that the dynamics of EBCs lead to large changes in sound speed and distort the vertical sound speed profile. The greatest change in sound speed in either region is caused by upwelling in the NCCS. Surface and associated subsurface eddies in the LCS are the largest scale feature in the study. The undercurrent of the NCCS and Meddies present the most intense (horizontal and vertical) gradients of sound speed change. / US Navy (USN) author.