Shear and extensional flows of dilute polymer solutions were studied experimentally in an attempt to understand the mechanism of polymer-induced drag reduction. A flowcell capable of simulating the dynamics of a turbulent boundary layer, involving the motion of counter-rotating vortices, was designed and fabricated. The pressure drop across the flowcell was measured for different flow arrangements, first with a Newtonian fluid and then with drag reducing, dilute polymer solutions. The pressure drop in excess of the Newtonian baseline, after accounting for viscous effects, was used as a measure of elastic effects. With the dilute polymer solutions, elastic effects were observed both in shear, extensional, as well as presheared extensional flows. These effects can be attributed to additional normal stresses generated by shearing. For extensional flows, the observed effects were independent of elongation rates, indicating that a conclusion regarding the mechanism of drag reduction cannot be made from the flowfield investigated.

Mushrooms are one of the protein rich foods, however they have a short pro-harvest life (2 to 3 days) compared to most vegetables. The aim of this study was to evaluate whether applying an anti-browning solution using vacuum impregnation and then electron beam irradiation can be used to extend the shelf life of fresh-cut mushrooms (Agaricus bisporus). Solutions made with (a) 2% ascorbic acid + 1% calcium lactate, (b) 2% citric acid + 1% calcium lactate, (c) 1% chitosan + 1% calcium lactate, and (d) 1% calcium lactate were used to impregnate mushroom slices at different vacuum pressures, vacuum pressure times, and atmospheric restoration times. Mushrooms were also irradiated at a dose of 1 kGy using a 1.35 MeV e-beam accelerator and their quality was evaluated in terms of color, texture, and microbial growth during 15 days storage at 4 degrees C. The best vacuum impregnation treatment was the 2% ascorbic acid and 1% calcium lactate solution using a vacuum pressure of 50 mmHg for 5 minutes and an atmospheric restoration time of 5 minutes. The control (not treated) and impregnated samples lost their structure (softening) during storage. The irradiated samples lost their firmness by day 4 of storage. The addition of calcium lactate to the samples during the treatment helped to keep the product’s texture during the 15 days storage time. Color of the mushrooms changed during storage for all the control and impregnated samples and only the irradiated samples showed an acceptable color by the end of day 15. Aerobics and psychrotrophics counts were significantly reduced by irradiation; while yeast and molds population increased by day 9 and were not completely inactivated with a dose of 1 kGy. Sensory panelists preferred the treated samples over the controls. The best treatment was the combination of vacuum impregnation with irradiation according to the consumer studies.

Quadriceps muscle weakness is a condition that can result from a wide variety of causes, from diseases like polio and multiple sclerosis to injuries of the head and spine. Individuals with weakened quadriceps often have difficulty supplying the knee-extension moments required during common mobility tasks. Existing powered orthoses that provide an assistive knee-extension moment are large and heavy, with power supplies that generally last less than two hours. A new device that provides a knee-extension-assist moment was designed to aid an individual with quadriceps muscle weakness to stand up from a seated position, sit from a standing position, and walk up and down an inclined surface. The knee-extension-assist (KEA) was designed as a modular component to be incorporated into existing knee-ankle-foot-orthoses (KAFO). The KEA consists of three springs that are compressed, as the knee is flexed under bodyweight, by cables that wrap around a sheave at the knee. The KEA returns the stored energy from knee flexion as an extension moment during knee extension. During swing or other non-weight bearing activities, the device is disengaged from the KAFO by decoupling the sheave from the KAFO knee joint, allowing free knee joint motion. A prototype was built and mechanically tested to determine KEA behaviour during loading and extension and to ensure proper KEA function. For biomechanical evaluation, able-bodied subjects used the prototype KEA while performing sit-to-stand, stand-to-sit, ramp ascent, and ramp descent tasks. The KEA facilitated sitting and standing, providing an average of 53 % of the required extension moment for the two participants, which allowed one participant to reduce quadriceps usage by 38 % and the other to perform sit-to-stand in a slower and more controlled manner that was not possible without the KEA. KEA use during ramp gait caused an overall increase in quadriceps activation by 76 %, on average, with use. Future efforts will be made to modify the design to improve functionality, especially for ramp gait, and to reduce device size and weight.

Demonstrations that ageing and life-span can be manipulated in model animal species have increased hopes that the length of the human life-span may also be dramatically extended. The possibility of human life-span extension has provoked debate amongst bioethicists. Proponents of life-extension cite the benefits of a longer and healthier life. Opponents argue that these technologies: violate human nature; may not necessarily increase the quality of life; and, they will lead to overpopulation and social strife that outweighs any benefits to individuals. Others see problems of equity and justice in access to any potential life-extension technologies. The attitudes of members of the public have largely been neglected in ethical and policy discussions of human life-extension. In the absence of empirical evidence on public attitudes, proponents and opponents have assumed either widespread public enthusiasm for life-extension or strong opposition because of concerns about its moral acceptability or its adverse social consequences. All agree that public attitudes could be a powerful facilitator or a major obstacle to the development of life-extending technologies. The goal of this thesis is to characterise public attitudes towards life-extension and describe factors that influence these views. It examines the following questions: (1) What is the prevalence of public support for (or opposition to) life-extension research? (2) How much interest is there among the public in using a technology that could increase life-span by slowing ageing? (3) What issues are important to members of the public in forming their attitudes? (4) What ethical issues, if any, do members of the public identify? (5) Are these ethical and moral issues the same ones expressed by ethicists and social scientists? (6) How do these ethical attitudes affect their overall interest in, or support for, life-extension? (7) How are attitudes towards life-extension related to demographic characteristics such as age, gender, education, and religious beliefs? Three empirical studies were designed using a mixed methodology to answer these questions. Study 1 (focus groups) and Study 2 (individual interviews) were qualitative investigations of public attitudes towards life-extension. The results of these two studies informed the design of Study 3 - a quantitative survey of attitudes towards life-extension via telephone interviews with 605 adult members of the Australian public. Participants in Study 3 were presented with a vignette outlining the prospect of a life-extension pharmaceutical that could increase life-span to 150 years by slowing the ageing process. They were then asked to express their level of agreement with a series of statements about ethical, social and personal implications of life-extension, and their overall support and interest in using such a technology. All three studies found mixed public attitudes towards the development and use of life-extension technologies. Participants in Studies 1 and 2 were concerned about whether life-extension would be accompanied by good quality of life. Studies 1 and 2 also suggested that participants were concerned about social and ethical issues that included: the potential impact on society; whether life-extension was “natural”; and whether access to life-extension technologies would be fair and equitable. Study 3 confirmed the diversity of public views identified in the qualitative phase. While 65% supported such research, only 35% said that they would use a life-extension technology if one became available. Men were more supportive of research and more disposed to use life-extension technologies than women. 58% of participants expressed ethical or moral concerns about life-extension technologies. When asked to weigh up the potential benefits and negatives that they identified as important, almost half (48%) said that life-extension technologies would do more harm than good to society, and 40% thought that taking a life-extension pharmaceutical would do them more harm than good personally. Study 3 also showed that valid scales could be constructed to assess the strength of concerns about social and ethical issues. These scales were: personal benefits/negatives; social benefits/negatives; and natural concerns. Higher levels of support for using and developing life-extension technologies were associated with higher levels of perceived personal and societal benefits from life-extension. Participants who had more ethical concerns, and perceived more personal and social negatives were less likely to support or express an interest in using life-extension technologies. Perceptions of personal and social benefits, and having concerns about the “naturalness” of life-extension were the best predictors of support or interest in using life-extension technologies. This thesis shows that public attitudes towards life-extension are more varied than some ethicists have assumed. While there are substantial minorities who were clearly “pro” or “con”, many members of the public are concerned about ethical and social issues. It would be unwise for researchers of life-extension not to take account of public attitudes and concerns if they hope to foster public support for their work.

Thesis (Ed.D.)--Georgia Southern University, 2007. / "A dissertation submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Doctor of Education." Education Administration, under the direction of Walter S. Polka. ETD. Electronic version approved: December 2007. Includes bibliographical references (p. 128-149) and appendices.

Zugl.: München, Techn. Univ., Diss., 2007

Thesis (Ed.D.)--Teachers College, Columbia University, 1964. / Typescript; issued also on microfilm. Sponsor: Paul L. Essert. Dissertation Committee: Walter E. Sindlinger. Includes bibliographical references.

Thesis (M.S.P.H.)--University of Michigan, 1944.

Thesis (M.S.P.H.)--University of Michigan, 1944.

Thesis (Ph. D.)--University of Wisconsin, 1976. / Extension Repository Collection. Typescript (photocopy). Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 145-150).