Sputtering and the annealing of radiation damage in single crystal semiconductors

Single crystals of germanium, silicon and indium antimonide were bombarded with medium energy (5, 10, 15 keV) rare gas ions and the effects arising from the interaction of these ions with target atoms studied. Incidence of energetic ions in the crystal is followed by ejection of lattice atoms from their normal positions. The ejection of atoms from the bombarded surface was studied with two methods, namely the sputtered atom ejection pattern technique and monitoring of the sputtering yields using a mass spectrometrie technique. Ejection patterns were collected from (111) and (100) surfaces of silicon, (111), (110) and (100) surfaces of germanium and (ill), (110) and (100) surfaces of indium antimonide. The patterns were examined as functions of ion mass, ion energy, target temperature and species, and target orientation. Major ejection directions of target species were determined. In addition the ejection patterns from the elemental semiconductors were compared with those from compound semiconductors and significant differences were found. The results were analyzed on the basis of current models of anisotropic ejection from semiconductors. For quantitative evaluation of the sputtering process a mass spectrometric technique was developed. This technique, which is reported in detail, was employed in following the variation of relative sputtering yields with ion beam incidence direction as the target was rotated about the normal. Critical angles for channelling were determined from the data, and the results compared with the models of Onderdelinden (1968) and with the transparency model. In addition both techniques were used to study the production and insitu annealing of i o n bombardment induced damage. The rate of production was observed to depend on ion energy , ion mass, target species and orientation , target temperature and dose rate , Activation energies for the annealing processes were calculated . The thesis commences with a review of relevant experimental and theoretical aspects of ion -crystal interaction

Study of the effectiveness of informatics policy instruments in Africa

French version available in IDRC Digital Library: Etude de l'efficacité des instruments politiques dans l'informatique en Afriqu

Zimbabwe : status of informatics

Meeting: Regional Seminar on National Information and Informatics Policies for Africa, 28 Nov.-Dec. 1988, Addis Ababa, ETIn IDL-393

Étude de l'efficacité des instruments politiques dans l'informatique en Afrique

Version anglaise disponible dans la Bibliothèque numérique du CRDI: Study of the effectiveness of informatics policy instruments in Afric

National informatics policies in Sub-Saharan Africa

Meeting: Regional Seminar on National Information and Informatics Policies for Africa, 28 Nov.-Dec. 1988, Addis Ababa, ETIn IDL-393

Key barriers and enablers associated with uptake and continuation of oral pre-exposure prophylaxis (PrEP) in the public sector in Zimbabwe: Qualitative perspectives of general population clients at high risk for HIV.

BACKGROUND:Understanding the perspectives and preferences of clients eligible for pre-exposure prophylaxis (PrEP) is essential to designing programs that meet clients' needs. To date, most PrEP programs in limited-resource settings have been implemented by partner organizations for specific target populations, but the government of Zimbabwe aims to make PrEP available to the broader population at substantial risk in public sector clinics. However, there is limited information on general population perspectives about PrEP in Zimbabwe. METHODS:A qualitative study was conducted to explore clients' motivation to take or decline PrEP and continue or discontinue PrEP. Through a PrEP pilot in one urban family planning clinic and one rural youth center in Zimbabwe, 150 HIV-negative clients screened as being at high risk of HIV and were offered PrEP between January and June 2018. Sixty semi-structured interviews were conducted with clients who agreed to follow-up (including 5 decliners, all from the rural youth center, and 55 accepters, with 42 from the rural youth center and 13 from the urban family planning clinic). Interviews were conducted after either the first or second PrEP follow-up appointment or after the client declined PrEP. Interviews were audio recorded, de-identified, transcribed, and coded thematically. RESULTS:PrEP uptake was driven by risk perception for HIV, and in many cases, that risk was introduced by the unsafe behavior or HIV-positive status of a partner. Among sero-discordant couples (SDCs), the desire to safely conceive a child was also cited as a factor in taking PrEP. Clients who opted for PrEP preferred it to other forms of HIV prevention. SDCs reported decreased condom use after PrEP initiation and in some cases were using PrEP while trying to conceive a child. After initiating PrEP, clients had more confidence in their sexual relationships and less stress associated with negotiating condom use. Family and partner support was critical to starting and continuing PrEP, but some clients stopped PrEP or missed appointments due to side effects or logistical challenges such as transportation. CONCLUSIONS:Results of this study can be used to provide operational guidance for national public sector roll-out of PrEP as part of combination HIV prevention in Zimbabwe. Based on feedback and experiences of clients, the training materials for health workers can be refined to ensure that health workers are prepared to counsel clients on the decision to start and/or continue PrEP and answer common client questions. Program advertisements should also be targeted with key messages that speak to client experiences. TRIAL REGISTRATION:Clinical Trial Registry Number: PACTR201710002651160

‘Out of place’? An auto-ethnography of refuge and postcolonial exile

The nature of postcolonial exile has changed considerably over the last two or three decades. The demography of migrants has shifted from intellectual dissidents and the participants in brain drain exoduses to all kinds of refugees and asylum seekers. Scholarship on this subject is vast but there is one group that is emerging and scarcely understood – the African-Australians of refugee background. This article seeks to contribute a part of that story using autobiographical or auto-ethnographical insight. My choice of this approach is predicated on the belief that it exploits personal experiences as units within the collective experience of a people. As a refugee from Sudan with some years in Kenya, I have found by experience and in autobiographies of others that blackness trumps African-ness in Diasporic identity constructions in the Western world. This, I argue, masks the ways in which African-Australians are generally understood as reflected in public discourse