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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Construction of a library of the plasmids of Bacillus thuringiensis subsp. israelensis and identification of a lameda clone encoding the 135 kDa mosquitocida polypeptide

Litz, Sara Leandra January 1990 (has links)
Bacillus thuringiensis subsp. israelensis (B.t.i.) produces a plasmid encoded parasporal crystalline protein which is larvacidal to mosquitoes carrying parasites for malaria and other infectious diseases. The purpose of this study was to construct a library of random fragments from the nine plasmids of wild type B.t.i. strain 402. The library was to be utilized in order to clone a 135kDa mosquitocidal polypeptide carried on a 108 kb B.t.i. plasmid.The library construction involved isolation of plasmid DNA by equilibrium density centrifugation, generation of random fragments of the nine plasmids by a partial Sau3A restriction digest, and ligation of these fragments into XbaI-BamHI restricted Lambda GEM-11 vector. Escherichia coli strain LE392 was infected by the packaged recombinant lambda and over 1000plaques were pooled to comprise the library. In order to verify construction of the library, both plaque screens of the library and Southern Analysis of restricted clones subjected to agarose gel electrophoresis were performed with labeled probes. The labeled probes were included: 1) radioactive end-labeled oligonucleotides constructed from published sequences of the B.t.i. 135 kDa toxic protein, 2) radioactive end-labeled random fragments from all nine plasmids of B.t.i., 3) radiolabeled entire plasmids of all nine plasmids of B.t.i., and 4) dioxigenin-labeled oligonucleotides. No homology between the lambda library digested DNA and the B.t.i. plasmid was observed. The results suggested that no lambda library of B.t.i. was constructed and, therefore, a lambda clone encoding the 135 kDa mosquitocidal polypeptide was not isolated. / Department of Biology

The treatment of rusted steel with mimosa tannin

Francis, R. A. January 1976 (has links)
No description available.

Critical analysis of the existing food sampling programmes

Wong, Raymond Y. P. January 2000 (has links)
Existing food sampling programmes used by the local authorities, if they exist, operate in a 'hit or miss' fashion, and the use of small sample size is common in the programmes. Although the U.K. food co-ordination network is well developed, the complexity of the three-way systems creates many complications and duplications. Also, compliance with the European legislation generates extra burdens to the U.K. governments. A national survey was undertaken in 1998 to investigate the purpose and effectiveness on local authonty food sampling. Although only half of the returns believed that local food programmes contributed significantly to the prevention of foodborne illness, over three-quarters agreed that the programmes could be improved upon. It was clearly shown that U.K. local authorities were eager to advance their sampling regime, but were handicapped by resource constraints. The local authorities stated that improvement could be achieved if sampling activities were increased. Because sampling involves errors due to uncertainties and variations, a statistically validated sampling model was developed in an attempt to determine suitable sample sizes under various sample proportions that would also satisfy good normal approximation in order to reduce margin of error to a minimum. However, the model illustrated that current sampling regimes were far from reaching the minimum requirement. In the main, if sampling has a part in food safety activities, then central government support towards sampling and analysis cost is vital. Routine sampling can be undertaken collectively at a regional basis, and such high cost may be split among local authorities. Alternatively, a requirement can be placed upon food premises to undertake their own sampling, and officers will then carry out local audits. Finally, further investigations should be extended to the determination of many contaminants' limits and the cost benefit analysis along the chain of causality.

The evolution of regional counterterrorism centers within a national counterterrorism network : is it time to fuse more than information?

Leavell, Ron 03 1900 (has links)
CHDS State/Local / There is widespread consensus among both policymakers and intelligence professionals that domestic counterterrorism efforts remain hampered by the lack of an effective national intelligence network that fully integrates the Homeland's entire intelligence assets and other related Homeland Security capabilities into one national counterterrorism system. The failure to unify our domestic counterterrorism efforts inhibits timely and complete information sharing and the evolution of a more robust Homeland Security prevention and response capacity. To achieve counterterrorism synergy we need a holistic approach that removes the intelligence element from its vacuum and fuses it in the counterterrorism crucible, along with the investigations element and related Homeland Security prevention and response operational elements, in Regional All-Hazards, Disaster and Anti-Terrorism Resource (R.A.D.A.R.) centers. These regional and super-regional R.A.D.A.R. centers can then be united into a National Counterterrorism Network under the auspices of the National Counterterrorism Center and the National Operations Center. Fusing this multi-government level, multi-disciplinary collaboration of intelligence, investigative and operational assets, along with the resources of key private sector groups into one unified organism would eliminate information sharing barriers, and will ensure the most efficient and effective use of Homeland Security resources to prevent and respond to terrorist attacks and natural disasters. / Seattle Police Department (author)civilian.

Crime prevention in urban areas in Nigeria: a historical perspective

Osula, Philip O 01 December 1983 (has links)
No description available.

Coming Together : Mechanisms behind attitude change regarding gender based violence

Piiroinen, Nadja January 2017 (has links)
In the field of gender based violence prevention more and more emphasis is being put on preventative efforts through attitude change. This study is the result of a minor field study in Rwanda and analyzes the mechanisms that are present during the process of attitude change. The purpose of this study is to isolate the mechanisms within this process. The study applies feminist theory and process tracing though elite interviewing. The analysis is built on 14 interviews with field officers working for the organization Rwanda Men's Resource Center as instructors on a gender based violence prevention program. It was found that attitude change is more likely when participants feel equal and not threatened, as well as when they were able to draw their own conclusions and be agents of their own ideas. Furthermore, when exposed to new ideas concretely through their personal relationship with a trainer, to their spouses, and through take-home exercises, participants gained new insights. To be successful the program required a long term commitment to the subject at hand. Ultimately, this signals that attitude change is a long and continuous process- of which lasting results can be achieved through continued reinforcement.

Complications and failures of secondary prevention in acute ischaemic stroke

Geraghty, Olivia January 2011 (has links)
Stroke is a leading cause of death and the most common cause of disability in adults in the United Kingdom. Several treatments are effective in preventing stroke in the long term after TIA and minor ischaemic stroke, including aspirin, other antiplatelet agents, and blood pressure lowering drugs, statins and anticoagulation in atrial fibrillation. However, failure of secondary prevention to prevent recurrent vascular events is still a major clinical problem, as is the risk of bleeding associated with antiplatelet agents and anticoagulants. This thesis determines the risks associated with urgent secondary prevention in the acute phase after TIA and minor stroke, particularly the reduction in risk of early recurrent stroke, the risk of bleeding with combination of aspirin and clopidogrel in the acute phase and whether or not there is a rebound increase risk of ischaemic stroke or recurrent TIA after withdrawal of a short course of clopidogrel. I have shown that urgent and early treatment of ischaemic stroke with secondary prevention leads to an 80% reduction in recurrent stroke. I have also shown that an increased bleeding risk exists among aspirin naïve patients treated with combination antiplatelet medications compared to those already treated with aspirin. My work has also shown that discontinuation of clopidogrel following treatment for 30 days or more does not lead to a rebound increase in ischaemic stroke. Bleeding events are a frequent complication of antiplatelet treatment in TIA and ischaemic stroke. I have shown that the long term risk of bleeding in a population study treated with antiplatelets is 6% per 100 person years. Using this information I identified risk factors for bleeding to develop a clinical baseline bleeding model to identify those at higher risk of bleeding. Age was identified as a significnant risk factor for both bleeding and recurrent ischaemic risk. In addition, bleeding events are associated with higher rates of fatality and disability in the older population. Finally, I have shown that the time trends in stroke recurrence differ depending on the presenting event i.e TIA or stroke. Stroke recurrence risk after minor stroke is delayed compared with TIA, and remains high during the late phase despite current best medical treatment. Blood pressure control and atrial fibrillation are risk factors for late stroke recurrence identifying the unmet need for better detection and treatment potentials to reduce late recurrent stroke.

Ecology of breeding sites and insecticide resistance of the potential malaria vectors in Mpumalanga Province, South Africa

Mbokazi, Manzane Frans 28 May 2015 (has links)
Thesis (M.Sc.(Med.))--University of the Witwatersrand, Faculty of Health Sciences, 2013.

Characterisation of Southern African strains of the malarial parasite plasmodium falciparum

Freese, Janet Anne January 1993 (has links)
A Thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg for the Degree of Doctor of Philosophy / This thesis describes the characterisation of southern African isolates of Plasmodium falciparum according to isoenzyme type, antigen variants and drug sensitivity. Nineteen southern African isolates and a Gambian reference isolate were cultured in vitro in gassed tissue culture flasks. Polyacrylamide gel electrophoresis with use of 5 enzymes revealed little variation amongst the isolates and the frequencies of enzyme forms were similar to those of isolates from other parts of the world. Antigenic diversity was demonstrated using a panel of 9 monoclonal antibodies in the indirect fluorescent antibody test. The antigenic composition of 70% of isolates was markedly different to any obtained in other geographical areas. Both characterisation techniques revealed a mixture of parasite types in some isolates. However I the characteristics of most of these heterogeneous isolates were not stable with time in culture. Most isolates proved to be resistant to chloroquine in a 48-hour growth inhibition test. A wide range in Pyrimethamine susceptibilities was detected although most isolates exhibited a low level of resistance to this drug. In the radioisotope uptake assay, the halofantrine IC50 values obtained were comparable with those of West African isolates but were higher than the TC50s of south-East Asian isolates. All of the isolates resistant to chloroquine in the 48-hour test were resistant in the radioisotope assay. However, 1 isolate shown to be sensitive to chloroquine in the first test was found to be resistant in the 3Hhypoxanthine incorporation method. This was assumed to be the result of selection of resistant clones. Southern African isolates were shown to be fully susceptible to mefloquine, but had reduced susceptibility to quinine and sulphadoxine/ pyrimethaInine. Most isolates were sensitive to amodiaquine. A field study of 31 KwaZulu isolates of P. falciparum obtained in 1987 and 1988 showed 29 to be resistant to chloroquine in the 24-hour microtechnique, with the majority being highly resistant. Chloroquine resistance was confirmed in this area in a field study carried out in 1989 but in 1990 all 4 isolates tested were sensitive to the drug. In 1989, 12 out of 13 KwaZulu isolates were resistant to amodiaquine and most isolates showed reduced susceptibility to quinine and sulphadoxine/ pyrimethamine. / Andrew Chakane 2018

Reformation of international judicial institutions as key to global conflict prevention

Nyuykonge, Wiykiynyuy Charles 19 March 2010 (has links)
MA, Faculty of Humanities, School of Social Sciences, University of the Witwatersrand, 2007 / The settlement of international disputes by peaceful means has been described as one of the principles basic to the whole structure of the international system. It has been contended that this principle is the natural corollary for the prohibition of the use of force in settlement of international disputes enshrined in Art. 24 of the United Nations Charter, and embodied in Art. 2 (3). The UN’s organ assigned this mediation role is the International Court of Justice (ICJ) for matters with respect to state responsibility. The International Criminal Court (ICC), the International Criminal Tribunal for Yugoslavia (ICTY), the International Criminal Tribunal for Rwanda (ICTR), and the Special Court of Sierra Leone are international tribunals with jurisdiction to try matters relating to individual criminal responsibility. At continental as well as at regional levels, some states have set up their own institutions to peacefully manage conflict amongst them and in the broader region. Nevertheless, the question—in a world where dispute settlement institutions and processes are supernumerary relative to conflicts, can they effectively serve as key to conflict prevention? remains a major concern. Based on critical research, this report inquires whether conflict prevention is mythical or an attainable objective and whether the international judiciary which is prima facie a conflict mediation body can catalyze conflict prevention. In attempting to answer these questions, an understanding of the concepts of free and fair trial is preponderant; coupled with understanding current debates about the undermining of international justice by the states.

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