Woven (also known as textile) composites are one class of polymer matrix composites with increasing market share in aerospace, autmobile, civil infrastructure applications mostly due to their lightweight, their flexibility to form into desired shape, their mechanical properties and toughness. Due to the viscoelasticity of the polymer matrix, time-dependent degradation in modulus (creep) and strength (creep rupture) are two of the major mechanical properties required by engineers to design a structure reliably when using these materials. Unfortunately, creep and creep rupture of woven composites have received little attention by the research community and thus, there is a dire need to generate additional knowledge and prediction models, given the increasing market share of woven composites in load bearing structural applications. In this thesis, an analytical creep model, namely the Modified Equivalent Laminate Model (MELM), was developed to predict tensile creep of plain weave composites for any orientation of the load with respect to the orientation of the fill and warp fibers, using creep of unidirectional composites. The model was validated using an extensive experimental involving the tensile creep of plain weave composites under varying loading orientation and service conditions. Plain weave epoxy (F263)/ carbon fiber (T300) composite, currently used in aerospace applications, was procured as fabrics from Hexcel Corporation. Creep tests were conducted under two loading conditions: on-axis loading (00) and off-axis loading (450). Constant load creep, in the temperature range of 80–2400C and stress range of 1-70% UTS of the composites, was experimentally evaluated for time periods ranging from 1–120 hours under both loading conditions. The composite showed increase in creep with increase in temperature and stress. Creep of composite increased with increase in angle of loading, from 1% under on-axis loading to 31% under off-axis loading, within the tested time window. The experimental creep data for plain weave composites were superposed using TTSP (Time Temperature Superposition Principle) to obtain a master curve of experimental data extending to several years and was compared with model predictions to validate the model. The experimental and model results were found in good agreement within an error range of +1-3% under both loading conditions. A parametric study was also conducted to understand the effect of microstructure of plain weave composites on its on-axis and off-axis creep. Additionally, this thesis generated knowledge on time-dependent damage in woven composites and its effect on creep and tensile properties and their prediction.

Since the seminal works of Wegener and Darwin the notion that things evolve, and the how and the why of it, has generated intense debate. The surface of the Earth, and the creatures that live on it, are not static entities. Landscapes evolve. Organisms evolve. Understanding the how and the why requires a firm understanding of a myriad of interdependent and complex variables such as (but not limited to) climate, ecology, and tectonics. Unravelling the complexities though which landscapes and ecosystems evolve requires a broad interdisciplinary approach, where multiple investigative tools are simultaneously brought to bear on a given question. The study of old lake sediments, or paleolimnology, is a marquee example of a powerful interdisciplinary methodology that has been used extensively in reconstructing the Earth's past. This work showcases two examples where the discipline of paleolimnology advances our understanding of evolution on a landscape scale and on a human scale. In the southwestern United States, a record of the processes involved during the late Miocene and early Pliocene (~ 5 Ma) evolution of a major continental river drainage - the Colorado River – is partially preserved along the southern border of Arizona and California as the enigmatic Bouse Formation. And in southern Kenya, nearly 170 meters of lake and wetland sediments that have accumulated in the Koora Plain preserve a one-million-year long record of the environmental conditions against which our species, Homo sapiens, evolved. My research allows me to conclude that the depositional environment of the Bouse Formation was lacustrine; a fully marine interpretation that has been previously proposed is untenable. I also demonstrate that over the past 1.0 Ma, Homo sapiens in southern Kenya evolved against a backdrop of increasing regional aridity.

Libya as many other regions under arid climates suffer from inadequate water resources to cover all the needs of this rapidly developing country. Increasing water amounts for population supply, agricultural irrigation and use for industry are needed. As groundwater is the main water source in the country it represents a natural resource of the highest economic and social importance. Conceptual and numerical models were implemented in a regional scale to show how the natural situation has been changed after heavy groundwater abstraction having occurred in the last decades in the northwestern part of Libya. Results of the numerical model indicated that the current zones of depression in piezometric surface could have been caused by smaller withdrawn amounts than previously estimated. Indicated differences in assessed withdrawn groundwater volumes seem to be quite high and might influence considerably the future possibilities of groundwater use in the study region. 6

On October 13, 2010, President Barack Obama signed the Plain Writing Act of 2010 into law. It requires federal government agencies to use plain writing in all "covered" documents "the agency issues or substantially revises" (Sec. 4 (b)). The goal of the Plain Writing Act is to "enhance citizen access to Government information" (Introduction) and improve government operations and accountability "by promoting clear Government communication the public can understand and use (Sec. 2). This dissertation examines what plain language, as the Act defines it and the U.S. federal government (USG) is implementing it, means and does at the various levels of language policy -- institutional, writer, and user. I argue that "real" plain language policy differs from the policy documented by the Plain Writing Act of 2010. While plain bureaucratic writing can help to make government documents more understandable for users, plain writing alone cannot achieve the Act's goals. Plain writing is a style of writing. As such, it is not only contingent, but it is also subjective and based on preference, which is impossible to legislate. Hence, plain bureaucratic writing is and does different things at different levels of language policy. Moreover, institutional- and writer-level representations of plain bureaucratic writing are at odds with user representations in many respects. Plain bureaucratic writing for USG agencies and federal writers is another way to describe good writing in the tradition of Edited American English and "fixes" the problem of bad government writing. At the user level, understandable writing is plain writing, regardless of whether it adheres to the principles of standard written English or the plain style. Plain language legislation does not affect the work of most writers in the study or their ability to do it. Nonetheless, user participants generally prefer plain language, reporting that they are more inclined to do what a government document intends for them to do when they understand it. Efforts to enhance government communication should focus on usability instead of plain language since usability is a better measure of the extent to which plain bureaucratic writing impacts the textual government-citizen interaction. / Ph. D.

The objectives of this paper are to raise awareness of the methodological standards that can affect the quality of radiographer plain-film reading performance studies and to determine the frequency with which these standards are fulfilled. Multiple search methods identified 30 such studies from between 1971 and the end of June 1999. The percentage of studies that fulfilled criteria for the 10 methodological standards were as follows. (1) Performance of a sample size calculation, 3%; (2) definition of a normal and abnormal report, 97%; (3) description of the sequence of events through which films passed before reporting, 94%; (4) analysis of individual groups of observers within a combination of groups, 50% (5) appropriate choice of reference standard, 80%; (6) appropriate choice of arbiter, 57%; (7) appropriate use of a control, 22%; (8) analysis of pertinent clinical subgroups, e.g. body areas, patient type, 44%; (9) availability of data for re-calculation, 59%; and (10) presentation of indeterminate results, 69%. These findings indicate variation in the application of the methodological standards to studies of radiographer's film reading performance. Careful consideration of these standards is an essential component of study quality and hence the validity of the evidence base used to underpin radiographic reporting policy.

No / The immobilisation and restraint of children to facilitate radiographic examination is a controversial issue that has been relatively ignored by radiography research. The aim of this study was to begin to fill this gap by providing a description of restraint used in a limited number of clinical sites in order to highlight any perceived need for training, policies or guidelines in the use of child immobilisation and restraint. Methods: A cross-sectional survey design using a postal questionnaire was adopted. One hundred and sixty-seven questionnaires were distributed to radiographers employed within six hospital Trusts. Results: A response rate of 83.2% (n=139/167) was achieved. Ninety-three percent (93.5%, n=130/139) of respondents indicated that restraining techniques were used although only 19.2% (n=25/130) had received specific training in safe restraining techniques and 7.9% (n=11/139) in distraction techniques as an alternative to restraint. A need for further guidance and support for clinical staff was evident with 73.3% (n=74/101) of respondents identifying a need for specific guidelines and 84.6% (n=110/130) indicating that further training opportunities were required. Conclusions: The use of restraint in paediatric plain film radiography is an apparently widespread practice and support for clinical radiographers through the development of training opportunities and practice guidelines are seen as essential in order to promote high quality paediatric radiography practices.

Astragalus oniciformis Barneby is a xerophyte of the sagebrush deserts of central Idaho. It is a narrow endemic of the upper Snake River Plains where it inhabits stabilized, aeolian sand deposits over Quaternary basalt flows. The objective of this study was to determine the levels and distribution of genetic differentiation within and among populations of Astragalus oniciformis. Fifteen individuals from each of eight populations, chosen from throughout the range of the species, were selected for their accessibility, density of individuals, and large population size. Two disjunct eastern populations selected for this study have been separated from the continuous western populations for 3600 years by an eight-mile wide, inhospitable lava flow. Inter-simple sequence repeats (ISSR) were chosen as the marker to assess genetic differentiation. Two primers were selected that yielded 40 loci, all of which were polymorphic in A. oniciformis. In an analysis of molecular variance (AMOVA), 88.69 percent of the variation was significantly attributed to variation within populations. The differentiation between the two disjunct populations and the western populations was insignificant. High gene flow (Nm=3.91-3.93) and a low percent deviation from Hardy-Weinberg equilibrium due to population subdivision (G[subscript st]=0.113-0.1134) were found among populations of A. oniciformis. These results suggest that current threats to this species, ranging from plant community changes due to changing fire patterns, habitat alteration from livestock grazing, and habitat loss from agricultural development have not yet affected the genetic diversity of this species. Preservation of the numerous, large populations and the high gene flow will help insure that the levels of genetic diversity found in Astragalus oniciformis will not decrease. / Graduation date: 2002

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