Cross-classified random effects models (CCREMs) are used in the analyses of cross-sectional and longitudinal multilevel data that are not strictly hierarchical. Because of the complexity of this technique, many researchers simply ignore the cross-classified structures of their data and use hierarchical linear models. The study simulated crosssectional and longitudinal multilevel data with cross-classified structures and examined the impact of misspecifying CCREMs on parameter and standard error estimates in these data. The dissertation consists of two studies. Study One examines cross-sectional multilevel data and Study Two examines longitudinal multilevel data. In Study One, three-level cross-classified data were generated. Two random factors were crossed at either the top level or the intermediate level. It was found that ignoring a crossed random factor causes the variance of the remaining crossed factor and the adjacent levels to be overestimated. The fixed effects themselves are unbiased; however, the standard errors associated with the fixed effects are biased. When the ignored crossed factor is at the top level, the standard error of the intercept is underestimated whereas the standard error of the regression coefficients associated with the covariate of the intermediate level and the remaining crossed factor are overestimated. When the ignored crossed factor is at the intermediate level, only the standard error of the regression coefficients associated with the covariate of the bottom level is overestimated. In Study Two, longitudinal multilevel data were generated mirroring studies in which students are measured repeatedly and change schools over time. It was found that when the school level is modeled hierarchically above the student level rather than as a crossed factor, part of the variance at the school level is added to the student level, causing underestimation of the school-level variance and overestimation of the studentlevel variance and covariance. The standard errors of the intercept and the regression coefficients associated with the school-level predictors are underestimated, which may cause spurious significance for results. The findings of the dissertation enhanced our understanding of the functioning of CCREMs in both cross-sectional and longitudinal multilevel data. The findings can help researchers to determine when CCREMs should be used and to interpret their results with caution when they misspecify CCREMs.

Conventional investigations into the performance of piston-rings in internal combustion engines are performed at relatively low speeds and consider only steady state operation conditions. Loss of power in internal combustion (IC) engines is becoming an increasing issue when they are operated at high engine speeds. This project is directed at developing technology to establish whether this phenomenon is influenced by a lubricant related effect. In a normal operating environment automotive engines typically operate under transient operating conditions. These rapid changes in operation conditions may influence the thickness of the hydrodynamic film which lubricates the interfaces between the piston-ring and liner. During this project two capacitance methods were employed in a fired compression ignition engine, an amplitude modulated (AM) system originally developed by Grice and a new "high speed" capacitance technique based on a frequency modulated principle. The first part of this thesis is concerned with the development and implementation of a new apparatus suitable for measuring the thickness and extent of the hydrodynamic oil film which lubricates the piston-rings and liner. The nature of the working principle of the high speed capacitance measurement system required the design, manufacture, assembly and commissioning of a novel dynamic calibration apparatus. The new system can also be used for static calibration (AM system) of capacitance based distance measuring systems. It uses a manufacturer calibrated closed loop controlled piezo-actuator to present a target relative to the sensor face. Some previous investigations concluded a stable oil film thickness. However, this work shows that there are cyclic variations of the oil film thickness OFT on a stroke to stroke and cycle to cycle basis. A series of measurements was conducted under various fixed speed load points. The effects of using lubricants of different viscosity on the minimum (OFT) between liner and piston ring have been little studied and this work shows that it was possible to speciate measurements of different lubricants. This thesis also describes a measurement of the oil film thickness during abrupt changes in engine operating conditions.

The present study investigated estimation of the variance of the cross-classified factors’ random effects’ interaction for cross-classified data structures. Results for two different three-level cross-classified random effects model (CCREM) were compared: Model 1 included the estimation of this variance component and Model 2 assumed the value of this variance component was zero and did not estimate it. The second model is the model most commonly assumed by researchers utilizing a CCREM to estimate cross-classified data structures. These two models were first applied to a real world data set. Parameter estimates for both estimating models were compared. The results for this analysis served as a guide to provide generating parameter values for the Monte Carlo simulation that followed. The Monte Carlo simulation was conducted to compare the two estimating models under several manipulated conditions and assess their impact on parameter recovery. The manipulated conditions included: classroom sample size, the structure of the cross-classification, the intra-unit correlation coefficient (IUCC), and the cross-classified factors’ variance component values. Relative parameter and standard error bias were calculated for fixed effect coefficient estimates, random effects’ variance components, and the associated standard errors for both. When Model 1 was used to estimate the simulated data, no substantial bias was found for any of the parameter estimates or their associated standard errors. Further, no substantial bias was found for conditions with the smallest average within-cell sample size (4 students). When Model 2 was used to estimate the simulated data, substantial bias occurred for the level-1 and level-2 variance components. Several of the manipulated conditions in the study impacted the magnitude of the bias for these variance estimates. Given that level-1 and level-2 variance components can often be used to inform researchers’ decisions about factors of interest, like classroom effects, assessment of possible bias in these estimates is important. The results are discussed, followed by implications and recommendations for applied researchers who are using a CCREM to estimate cross-classified data structures. / text

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The purpose of this thesis is to increase understanding and contribute to knowledge about the attitudes and behaviour of men in contemporary France and Britain. The thesis has three main aims: firstly, to provide the first cross-national comparison of French and British writing and research on the place of men in contemporary society; secondly, to identify similarities and differences in the roles of men in France and Britain; and thirdly, to determine to what extent and in what way such similarities and differences are linked to the social structures and cultural background of each country. The thesis focusses on two main facets of the male experience: the relationship between men and women and the interaction between fathers and their children. Men's attitudes and behaviour are examined in relation to issues such as the division of household tasks and child care within the family, parental roles, female employment, role reversal, gender stereotyping and changes towards a new image of masculinity in society. Particular consideration is given to differences in governmental attitudes in France and Britain towards the introduction of family policy measures for men as fathers. The thesis ends with a discussion of legislative, social and educational measures which could be introduced in France and Britain in order to promote greater flexibility in men's roles and consequently improve gender equality in each country. The data analysed in the thesis are derived from a questionnaire-based empirical study involving 101 men in Britain and seventy-five men in France. The respondents' experience of and attitudes towards their roles in society are analysed and interpreted in the light of profile data relating to their family circumstances and with reference to knowledge about the broader socio-cultural context.

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The work described in this thesis is concerned with mechanisms of contact lens lubrication. There are three major driving forces in contact lens design and development; cost, convenience, and comfort. Lubrication, as reflected in the coefficient of friction, is becoming recognised as one of the major factors affecting the comfort of the current generation of contact lenses, which have benefited from several decades of design and production improvements. This work started with the study of the in-eye release of soluble macromolecules from a contact lens matrix. The vehicle for the study was the family of CIBA Vision Focus® DAILIES® daily disposable contact lenses which is based on polyvinyl alcohol (PVA). The effective release of linear soluble PVA from DAILIES on the surface of the lens was shown to be beneficial in terms of patient comfort. There was a need to develop a novel characterisation technique in order to study these effects at surfaces; this led to the study of a novel tribological technique, which allowed the friction coefficients of different types of contact lenses to be measured reproducibly at genuinely low values. The tribometer needed the ability to accommodate the following features: (a) an approximation to eye lid load, (b) both new and ex-vivo lenses, (c) variations in substrate, (d) different ocular lubricants (including tears). The tribometer and measuring technique developed in this way was used to examine the surface friction and lubrication mechanisms of two different types of contact lenses: daily disposables and silicone hydrogels. The results from the tribometer in terms of both mean friction coefficient and the friction profiles obtained allowed various mechanisms used for surface enhancement now seen in the daily disposable contact lens sector to be evaluated. The three major methods used are: release of soluble macromolecules (such as PVA) from the lens matrix, irreversible surface binding of a macromolecule (such as polyvinyl pyrrolidone) by charge transfer and the simple polymer adsorption (e.g. Pluoronic) at the lens surface. The tribological technique was also used to examine the trends in the development of silicone hydrogel contact lenses. The focus of the principles in the design of silicone hydrogels has now shifted from oxygen permeability, to the improvement of surface properties. Presently, tribological studies reflect the most effective in vitro method of surface evaluation in relation to the in-eye comfort.

Over the last twenty years the situation of women in the German Democratic Republic has been the subject of a considerable number of studies. The approach has generally been of a sociological or socio-political nature. In this thesis I propose to go one step further by examining the information that may be gained from literary sources. In a state where the media are subject to censorship, and thus controlled, one can refer to literature as an acknowledged source of inside information. Literary works often provide a forum for the formulation and discussion of ideas, which could not be aired elsewhere. Chapter 1 shows why literature, which had always been allocated a special role by the GDR's leading party, the SED, may be regarded as a reliable indicator of everyday life in that country. In this thesis I compare the findings of an analysis of women's literature with sociological data on the one hand and the portrayal of the "ideal" women in GDR media and official writings on the other. The thesis takes an interdisciplinary approach and draws on sources in political, legal, sociological, and cultural fields alike. This constellation of sources allows me to show that the views that female writers expressed in their works frequently coincide with sociological findings. Both of these sources were frequently found to be at odds with statements made in official writings and the media. Such insights could not have been provided by a study conducted from within one discipline.