This thesis is concerned with the response of multi-story prestressed concrete frames to seismic loading, and the ductility demands of the constituent members. In that regard, an idealized model for the end moment-plastic rotation relationship of prestressed concrete members was developed based on a published moment-curvature idealization for prestressed concrete. The idealized moment-rotation model, which included stiffness and strength degradation, was used to introduce all post-elastic action In a beam-column element, which consisted of an elastic beam connecting concentrated hinges modeled as nonlinear rotational springs. The subsequent use of the element in the nonlinear analysis of a typical multi-story prestressed concrete frame indicated that both the lateral displacements, and the girder end rotational and hinge curvature ductilities would be somewhat higher for a prestressed concrete frame than for a reinforced concrete frame with the same initial stiffness and strength. As an effort to limit deflections, and minimize member damage under moderate seismic loading the use of a higher base shear for a prestressed concrete structure than for a comparable reinforced concrete structure appears warranted. / Applied Science, Faculty of / Civil Engineering, Department of / Unknown

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Vincristine and vinblastine, two closely related alkaloids are extracted from the Madagaskar Periwinkle, Vinca rosea Linn. They have been shown to be effective oncolytic agents and cause arrest of mitosis at the metaphase stage, similar to that of colchicine andcolcimid. Clinically, vincristine has been found to produce a complete remission in patients with acute leukaemia. Tumour regression in patients with Hodgkin's disease, lymphosarcoma and certain childhood solid tumours have also been reported.

The focus of the study was the University of Dallas’ Rome Program, a mid-length study abroad program on the university’s campus in Rome, Italy. The program is designed to provide participants with the opportunity to encounter firsthand Western tradition by integrating the core curriculum through classroom teachings and class excursions, thus solidifying the foundation of the participants’ undergraduate education. Beyond this purpose, the Rome Program does not operate from established goals and objectives for student experience. I consulted relevant research literature to construct a schema of domains of development appropriate to this qualitative study. These domains were intellectual development, global perspective, career development, and spiritual development. I interviewed 20 University of Dallas seniors who participated in the mid-length study abroad program between fall 2009 and spring 2011, using an extended, semi-structured interview protocol. The participants included 11 females and 9 males; 19 White and 1 Hispanic. The findings were supported by subsequent review by 4 of the interviewed students. I found generally strong but inconsistent support for student development in each of the domains. A number of sub-themes are reported. Through the interviews, an additional theme of personal development emerged and is reported. Although the findings generally support the conclusion that the Rome Program is successful, good education practice leads to a recommendation of more explicit setting of goals by higher education program planners and administrators. Such goal setting provides rationale for program construction, provides students with their own goal framework, and establishes a tangible framework for ongoing program evaluation.

Vicia faba and investigating the effects of ionizing radiation on its root system. In particular, species such as Tradescantia, Pisum, Allium and Mordeum vulgare have been extensively studied. Nevertheless an ever-increasing number of workers have used Vicia faba for explaining the basic problems of radio biology. One of the reasons is the small number of large chromosomes contained in the root meristem cells, which are particularly conducive to simple cytological analysis. The seedlings also have other attractive features.

The interaction between sublesions produced by neutrons [p(66)/Be and d(16)/Be] and ⁶⁰Co γ-rays was investigated using mammalian cells, meristematic cells and human lymphocytes. The quality of each radiation source was quantified in terms of molecular yield per unit dose absorbed in a ferrous sulphate xylenol orange solution and was found to vary inversely with the mean LET of the radiation field. Inactivation parameters determined for mammalian and meristematic cells were not significantly different following simultaneous or sequential exposures to d(16)/Be neutrons and ⁶⁰Co γ-rays. Synergistic interaction was observed to be most pronounced in a radiation mixture consisting of about one part neutrons and three parts photons and appeared to be optimal at approximately 5 Gy. This phenomenon led to dose enhancement ratios that increase with radioresistance. Multi-target parameters indicated that on a per gray basis, priming doses of p(66)/Be neutrons and ⁶⁰Co γ-rays induce comparative levels of sublethal damage. However, non-parametric analysis of the survival data showed that mammalian cells regard a priming dose of neutrons as somewhat less effective than an iso-effective photon dose. A greater measure of synergy was observed between photons and priming doses of neutrons with less build-up. This is however mainly due to higher levels of biological damage induced with a more potent configuration of secondary charged particles. Interaction factors compared at levels of iso-effect tend to be smaller when the LET of the priming dose was increased. Split-doses of neutrons in the absence of build-up resulted in "negative" repair. The validity of proposed biophysical models was tested using meristematic cells, as the response of these cells show an apparent absence of intertrack damage. Contrary to expectations, synergistic interaction was observed for both growth delay measurements and micronuclear formations. Chromosome aberrations showed synergy between neutron and photon damage in human lymphocytes, as predicted by interaction functi ons. However, the synergistic interaction noted with micronuclear formation in binucleate cells was at variance with predictions based on biophysical models.

The magnetoresistance and Hall coefficient of two single crystals of bismuth have been measured at liquid helium temperatures. The purpose of the work was to investigate the non-linearities which had previously been observed in the longitudinal and Hall voltages as a function of current. In addition to continuous current measurements, a pulsed DC technique was used in an attempt to discriminate between the non-linear effects due to heating and a possible intrinsic current dependence of the magnetoresistance and Hall coefficient. The time dependence of both of these galvanomagnetic effects indicates that the rate of heat dissipation from the crystal into the normal helium increases suddenly about 50 rns after the current is applied. For example, at 4.2 K, 15 kG, and 50 mA, the sample temperature first rises to a value 0.2 K above the bath temperature, and then falls to a steady state value 0.06 K above the bath temperature. The resistance using a continuous current correlates with the steady state value of the time dependent resistance. A possible indication of gravitational dependence of the lambda transition was seen. Both above and below the lambda point the results of the low duty cycle pulsed DC measurements indicate the existence of an intrinsic non-ohmic effect when heating is minimized. The change in the resistance is of the order of I part per thousand per mA. In the normal fluid, the total current dependence of the magnetoresistance and the Hall coefficient is expressible as the sum of the intrinsic current dependence and that due to heating.

A research report submitted to the School of Public Health, Faculty of Health Sciences, University of Witwatersrand in partial fulfillment of the requirements for the degree of Master of Public Health. 20 October 2014 / Background: Health experts are calling sugar the new tobacco (Action on Sugar, 2014). The WHO recently revised its recommendations for a maximum daily limit on sugar intake of 25 grams. Yet a 2012 study showed that South African children and adolescents are consuming up to 50 grams and 100 grams per day respectively (Steyn et al., 2003). Sugar is now recognized for its role, not only in promoting caries, obesity and diabetes, but also in the development of cancers. The World Cancer Report 2014, warns of a ‘cancer tidal wave’ over the next 20 years (IARC, 2014) Health promotion alone is insufficient; drawing on the example of tobacco control, such as advertising restrictions, legislation is the key to prevention. The sugar-sweetened beverage (SSB) industry is the leader among all sectors in marketing to young people (Arredondo et al., 2009), thus a similar approach is recommended for restricting SSB advertising to reduce chronic disease risk. There is no data regarding SSB advertising and obesogenic environments in South Africa. This pilot study is the first to describe the location, content and characteristics of outdoor print advertisements for SSBs and fast foods in South Africa. Methodology: This is a secondary analysis of data collected as part of a larger 2013 study investigating the obesogenic environment in Soweto, South Africa. All visible outdoor advertising and branding of SSBs and fast food in a five-square kilometer demarcated area were included. Data on content, quantity, location, size and type of advertisements was collected in the field and a photograph was taken for further analysis. Comparisons were drawn to photographs of alcohol advertising in the same area. Data was captured using a coding sheet and was analysed descriptively and using inferential statistics. The advertisements included billboards, banners, posters, pole advertisements, painted signs, branded school signs, branded shop signs, directional signs and branded umbrellas and fridges. A total of 237 photographs were included in the study. Results: The main findings of this study indicate a significant presence of advertising and branding for sugar-sweetened beverages in Soweto. SSB and fast food advertising and branding accounted for 62.86% of all advertising in the area under study. Of all SSB and fast food brands available in South Africa, Coca-Cola accounted for 86.58% of this advertising and branding. Unlike alcohol advertising, which is restricted to the locations in which alcohol is sold, advertising for SSBs is pervasive throughout the community, seen everywhere from shops and schools to transit stops and on street sides. Most SSB advertising and branding signage is medium or large in size. Images of people were only present in a small number of the adverts. However when people were present, they were consistently young people under the age of 35. The race of people in the adverts consistently represented the black African demographic of Soweto. While the main goal of the adverts appears to be product and brand recognition, there is a trend across the SSB adverts to convey messages of happiness, positivity, friendship, fun and well-being, suggesting that consumption of these products would lend to such outcomes for the consumer. A small percentage also promoted special deals to encourage product purchase. Conclusion: SSB advertising in Soweto is extensive, far surpassing advertising for junk food or alcohol. The government should consider implementing legislation, to restrict SSB advertising. The country should also urgently move to adopt WHO’s new guidelines on the daily upper limit for sugar intake (Mann, 2012), and to limit SSB intake specifically, which should be reflected in revisions to South Africa’s food-based dietary guidelines. Further research should focus on the association between the high rate of exposure to SSB advertising in Soweto and the level of consumption of SSBs and on the understanding of the advertising environment and how this affects the health literacy of South African children and adolescents.

Boundary-layer flow over bodies such as aircraft wings or turbine blades is characterized by a pressure gradient due to the curved surface of the body. The boundary layer may experience modal and non-modal instability, and the type of dominant instability depends on whether the body is swept with respect to the oncoming flow or not. The growth of these disturbances causes transition of the boundary-layer flow to turbulence. Provided that they are convective in nature, the instabilities will only arise and persist if the boundary layer is continuously exposed to a perturbation environment. This may for example consist of turbulent fluctuations or sound waves in the free stream or of non-uniformities on the surface of the body. In engineering, it is of relevance to understand how susceptive to such perturbations the boundary layer is, and this issue is subject of receptivity analysis.   In this thesis, receptivity of simplified prototypes for flow past a wing is studied. In particular, the three-dimensional swept-plate boundary layer and the boundary layer forming on a flat plate with elliptic leading edge are considered. The response of the boundary layer to vortical free-stream disturbances and surface roughness is analyzed, receptivity mechanisms are identified and their efficiency is quantified. / QC 20101022 / 76218 VR Receptivity

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