The aim of this thesis is to study the energy fluctuations (leading to thermal fluctuations) during thermal and enzymatic denaturation of biological molecules and to study the variation in fluctuations between simple molecules like the DNA (which have only a secondary structure) to molecules with higher order structures and packaging. We have developed a new technique - Thermal Fluctuation Spectroscopy (TFS) to study these fluctuations. The technique of Thermal Fluctuation Spectroscopy (TFS) is a combination of microcalorimetry and noise measurement techniques. The combination of these two powerful techniques has never been exploited before. In this technique any energy exchange between sample and the substrate is reflected as a thermal fluctuation of the substrate. The system resolution is few parts per billion (ppb) and fluctuations in energy ~ 100nJ (which correspond to temperature fluctuations ~ K) can be measured. Chromatin is the basic building block of chromosome and this thesis focuses on the constituents this fundamental building block - DNA, histones and nucleosomes. Heteropolymeric dsDNA shows extremely large non-Gaussian fluctuation around its melting temperature. For homopolymeric DNA the fluctuations during denaturation are smaller. The thermal fluctuation during denaturation of a heteropolymer in buffer is several orders larger than when the DNA is on a substrate while that for a homopolymer is comparable in both cases. Our measurements established that heteropolymeric dsDNA denaturation occurs in two stages. Initially, at around 330 K, bubbles are formed in the AT rich regions. At higher temperatures, the GC rich regions binding them denature in a cooperative transition causing extremely large fluctuations. TFS on histone monomers showed that H1 monomer shows an increase in thermal fluctuation in the temperature range studied, while the core histones did not. We infer that this is due to the fact that the core histones may not be properly folded when they exist as monomers. It was seen that H1 crosses an energy barrier of 17 kcal/mol to go from its native to denatured state. The transition was kinetically driven with a fixed barrier till 352 K. At 352K, the barrier softened by ~ 1 kcal/mol leading to faster denaturation. The core histones when assembled as dimers/oligomers showed an increase in fluctuation at temperatures below 350 K. The assembling of these histones and DNA into a mononucleosome causes a very large increase in fluctuation over the entire temperature range studied. TFS showed that the fluctuation during mononucleosome denaturation was much larger than a simple sum of the fluctuations of its constituents. From the data we were able to identify that the denaturation starts with dissociation and unfolding of the core histones and the denaturation of AT rich regions of the DNA which leads to the breaking of some of the histone-DNA contacts. At higher temperatures the linker histone H1 and the GC rich regions of the DNA denature, leading to a collapse of the entire nucleosome structure. The broadness of the transition region (the fact that the fluctuation is large over the entire temperature range) was attributed to the presence of different types of contacts and interactions (with different energies) stabilizing the nucleosome structure. The nucleosome was found to favour large energy jumps over smaller ones indicating that the denaturation has an element of cooperativity involved. Using TFS we have been able to determine the fluctuations involved in the denaturation of biomolecules like DNA, histones and nucleosomes. The energy barriers to denaturation have been determined. We have also been able to give models for the denaturation of these biomolecules. We have also shown that it is possible to study enzymatic digestion using TFS. Thus, the technique of TFS is a viable tool for the study of fluctuations in reactions, in biomolecules, during transitions and in any process where there is an energy exchange involved.

Variability in daily relationship satisfaction has been shown to undermine future relationship well-being. The current study suggests that the relationship climate may moderate this effect. Namely, and in light of prior work showing that ignoring relationship issues can be detrimental for long-term relationship well-being, it is argued that when the relationship is characterized by more negative relationship experiences, variability in daily satisfaction may actually represent an adaptive acknowledgement of those experiences. Seventy-eight newly-married couples completed a 10-day daily diary task which assessed the variability of daily marital satisfaction, the positive and negative marital events taking place each day, and the daily coping strategies used to manage negative marital events. Spouses then reported on their global marital happiness as well as the severity of their marital problems every six months over the first two and a half years of marriage. Results revealed that when the marriage was characterized by more negative than positive marital events (i.e., a more negative marital climate), greater variability in daily satisfaction predicted initially lower levels of global marital happiness and more severe marital problems. However, greater variability in a more negative marital climate also was associated with less steep declines in global marital happiness and fewer increases in marital problems over time compared to low variability. Together, these findings suggest that variability in daily relationship satisfaction may temporarily feel unpleasant but over time may allow couples to address important relationship issues. / text

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This thesis contains four chapters. Each chapter constitutes an empirical exercise in which I apply econometric ideas on studying the dynamics of large cross sections of data (Random Fields). Three of them concern the empirics of convergence and the fourth analyses business cycle fluctuations. The first, "Notes on Convergence Empirics: Some Calculations for Spanish Regions," describes the econometric methods for studying the dynamics of the distributions and how to characterise convergence in this framework, explains why the standard cross-section regression analysis is misleading when testing for convergence and then performs some calculations for regions in Spain. The second chapter, "Dynamics of the Income Distribution Across OECD Countries", considers its baseline hypotheses to be those generated by the Solow growth model. Using sequential conditioning, it studies whether the convergence hypothesis implications can be shown to hold for the OECD economies. It finds that neither absolute nor conditional convergence, in the sense of economies approaching the OECD average, has taken place. The third chapter, "Cross Sectional Firm Dynamics: Theory and Empirical Results", extends ideas of distribution dynamics to a discrete choice setting, and extends the reasoning of Galton's Fallacy to the logit model. It provides evidence of the tendency of firm sizes to converge for the US chemicals sector by analysing dynamically evolving cross-section distributions. Finally, the fourth chapter, "Unemployment in Europe and Regional Labour Fluctuations" applies distribution dynamics ideas to a business cycle setting. It analyses the dynamics of employment for 51 European regions from 1960 to 1990, addressing the issue of whether regional shocks have aggregate effects on unemployment or the opposite. It uses a model for non-stationary evolving distributions to identify idiosyncratic and aggregate disturbances.

Thesis (Ph.D.)--Tufts University, 2004. / Adviser: Lawrence H. Ford. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 154-155). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph. D.)--University of Washington. / Bibliography: l. [72]-79.

Thesis (Ph.D.)--McMaster University (Canada), 1995. / Source: Dissertation Abstracts International, Volume: 56-12, Section: B, page: 6838. Adviser: J. P. Carbotte.

Thesis (M.S.)--State University of New York at Binghamton, Watson School of Engineering and Applied Science (Electrical Engineering), 2007. / Includes bibliographical references.

Resonance fluorescence from solid state devices have been motivated by the capability to obtain a bright source of antibunched and indistinguishable photons from a semiconductor chip. Such a photon source would be a strong candidate for applications in the quantum information field. In this thesis, an experimental setup to obtain high signal to noise resonance fluorescence from a single quantum dot is first presented. I then discuss the photon statistics, power spectrum, second-order correlation function and two-photon interference of the stream of resonance fluorescence. Particular emphasis is placed on a throughout investigation of spectral fluctuations caused by charge noise and Overhauser field generated by fluctuating nuclear spins in the quantum dot. In each case, it is found that noise can be overcome to generate single photons that exhibit high visibility two-photon interference. Finally, an interference effect caused by the interaction of a quantum dot and a nearby metal surface is presented. Preliminary analysis yields quantitative agreement with the data.

South African agriculture experienced rapid deregulation during the 1990s as the one channel marketing boards were dismantled. For the grains industry this meant the rapid development of a derivatives market (SAFEX). Derivative markets are surely the most intriguing and complex financial markets with the most misunderstood and riskiest instruments of all financial markets. Their complexity also caused its fair share of problems within the South African scenario with the inception of SAFEX in 1996/97. Not only is this type of market complex but it also creates huge fluctuations in the portfolio value of a derivatives linked portfolio. It is precisely this type of fluctuations and exposure that can be controlled and managed to the preferred level of risk by the correct and responsible application of these instruments. The successful application of these instruments depends greatly on the fact that the underlying market should be an efficient market which will then in turn allow for cost effective pricing of these instruments and ultimately lead to successful product structuring. The South African agricultural derivatives market was tested for efficiency by using a co-integration analysis which proved market efficiency. Once market efficiency was established it allowed for the structuring of marketing portfolios which ultimately resulted in a rule of thumb marketing strategy for maize producers. The strategy required the maize producer to fix a price during planting period for delivery in July the following year. In order for the producer to benefit from any potential upside during the season between price fixing and delivery the producer should buy a call option with an expiry date of the month of March following planting. This will save him at least four months worth of time value on the option premium. This study also acknowledged the fact that the derivatives market in South Africa is still in its fledgling phase and realises the vast potential for risk reduction through radical innovation by creating and mixing the basic positions of derivatives. This study illustrates by way of examples a few approaches in structured products. In an attempt to achieve successful product development the study applied portfolio theory as a means to quantify risk by using mean return and portfolio variance parameters. It addressed the more obvious price risk situation which is faced by all grain producers by developing a rule of thumb marketing strategy for farmers. The more complex situation of emerging agriculture was also considered where the objective was to enable a small scale producer to benefit from the risk reduction potential of these instruments. At the same time it would also allow them to access production credit without a traditional balance sheet while allowing the financier to be ring fenced from the risk of price fluctuation on the clients profit profile. A more adventures approach was followed for the dairy industry by creating a proxy price for milk based on the maize price of SAFEX in an attempt to encourage an increase in the volatility of the milk price which could then be managed very successfully through the use of derivatives which will then ultimately enable cash flow management. / Dissertation (MSc (Agricultural Economics))--University of Pretoria, 2008. / Agricultural Economics, Extension and Rural Development / unrestricted