Using non-experimental descriptive exploratory survey, this study sought to find out factors associated with delayed entry into HIV medical care among HIV positive people who are aware of their status. A quantitative design was used and a structured questionnaire was used as the data collection instrument. Respondents were patients in a hospital’s Opportunistic Infection Department whose hospital records indicated that they were HIV positive during the time of the study. The study found out that as much as 71.6% (n =43) first entered HIV medical care more than 12 months after testing HIV positive while 40% (n = 24) did so as a result of illness. Low education levels, unemployment and being single are associated with delayed entry into HIV medical care. A percentage of the population uses and trusts non-biomedical approaches to dealing with HIV/AIDS. Being diagnosed HIV positive is therefore not necessarily a strong reason enough for one to immediately enter into medical care. Intensive health education needs to be done at work places, health facilities, schools, through print and electronic media, churches and other community settings to equip the population with knowledge of the advantages of early entry into HIV care. / Health Studies / M.A. (Public Health)

Made available in DSpace on 2016-04-29T13:17:50Z (GMT). No. of bitstreams: 1 Aline de Carvalho Abdelnur.pdf: 1525676 bytes, checksum: 7ac17f7946c4f9d21776abe2bdcead58 (MD5) Previous issue date: 2013-11-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Skinner (1969/1980) described rules as contingency specifying stimuli with discriminative stimulus function. Based on this assumption, behavior analysts led much experimental research on rule-governed behavior and other possible behavioral functions of rules have not been investigated. Nevertheless a conceptual debate has started within Behavior Analysis about other functions of rules. This work is an experimental investigation on the function-altering effects of rules proposed in this conceptual debate. Another objective of this study was to investigate the effects of the statement of deadlines and consequences, alone or combined, on the behavior of Kindergarten children, when the opportunity to respond was immediate or delayed. Twenty children, aged from 4 to 5 years, were assigned into two experimental groups, following baseline. The study had two Parts. In Part I, rules with either a deadline OR a consequence for the specified response (or compliance) were studied. Group I was exposed to a sequence of experimental conditions that always started with immediate opportunity to respond. Group II was exposed to the same conditions, but always starting with delayed opportunity to respond. In Part II, attended 12 children, and rules specified both deadlines and consequences, always with immediate opportunity for the Group I and delayed opportunity for the Group II. The results demonstrate the function-altering function exerted by rules that specify deadlines and consequences, as well as extend other researchers data quantity and generality. Significant results were also obtained in terms of compliance with rules, under conditions of deadlines and / or consequences not previously investigated / Regras foram descritas por Skinner (1969/1980) como estímulos especificadores de contingências com função de estímulo discriminativo. A partir desta formulação, os analistas do comportamento conduziram muitas pesquisas experimentais sobre comportamento governado por regras, mas outras possíveis funções comportamentais de regras não foram investigadas. No entanto, foi iniciado um debate conceitual acerca de outras funções que as regras poderiam exercer. Este estudo caracteriza-se como uma investigação experimental dos efeitos alteradores de função de outros estímulos que as regras podem exercer. Outro objetivo deste estudo foi investigar os efeitos da declaração de prazos e consequências, isolados ou em combinação, sobre o comportamento de crianças da pré-escola, quando a oportunidade para seguir a regra era imediata ou atrasada. Participaram 20 crianças com idade entre 4 e 5 anos, que foram divididas em dois grupos experimentais, após a fase de linha-de-base. O estudo teve duas partes. Na Parte I, eram declaradas regras que especificavam apenas um prazo ou apenas uma consequência para a emissão da resposta especificada. O Grupo I foi exposto a uma sequência de condições experimentais que se iniciava sempre com oportunidade imediata para responder. O Grupo II foi exposto às mesmas condições, mas sempre iniciando com oportunidade atrasada para responder. Na Parte II, da qual participaram 12 crianças, eram declaradas regras que especificavam tanto um prazo como uma consequência, sempre com oportunidade imediata para responder para o Grupo I e oportunidade atrasada para o Grupo II. Os resultados obtidos atestam a função alteradora de função exercida por regras que especificam prazos e consequências, assim como permitem ampliar a quantidade e a generalidade de dados obtidos por outros pesquisadores. Resultados significativos em termos de seguimento, em condições de prazo e /ou consequência não investigadas anteriormente também foram obtidos

A series of experiments was performed with the Texas A&M University Nuclear Science Center Reactor (NSCR) to verify ²³⁵U delayed neutron emission rates. A custom device was created to accurately measure a sample's pneumatic flight time and the Nuclear Science Center's (NSC's) pneumatic transfer system (PTS) was redesigned to reduce a sample's pneumatic flight time from over 1,600 milliseconds to less than 450 milliseconds. Four saturation irradiations were performed at reactor powers of 100 and 200 kW for 300 seconds and one burst irradiation was performed using a $1.61 pulse producing 19.11 MW-s of energy. Experimental results agreed extremely well with those of Keepin. By comparing the first ten seconds of collected data, the first saturation irradiation deviated ~1.869% with a dead time of 2 microseconds, while the burst irradiation deviated ~0.303% with a dead time of 5 microseconds. Saturation irradiations one, three and four were normalized to the initial count rate of saturation irradiation two to determine the system reproducibility, and deviated ~0.449%, ~0.343% and ~0.389%, respectively.

CMOS technology scaling is bringing new challenges to the designers in the form of new failure modes. The challenges include long term reliability failures and particle strike induced random failures. Studies have shown that increasingly, the largest contributor to the device reliability failures will be soft errors. Due to reliability concerns, the adoption of soft error mitigation techniques is on the increase. As the soft error mitigation techniques are increasingly adopted, the area and performance overhead incurred in their implementation also becomes pertinent. This thesis addresses the problem of providing low cost soft error mitigation. The main contributions of this thesis include, (i) proposal of a new delayed capture methodology for low overhead soft error detection, (ii) adopting Error Control Coding (ECC) for delayed capture methodology for correction of single event upsets, (iii) analyzing the impact of different derating factors to reduce the hardware overhead incurred by the above implementations, and (iv) proposal for hardware software co-design for reliability based upon critical component identification determined by the application executing on the hardware (as against standalone hardware analysis). This thesis first surveys existing soft error mitigation techniques and their associated limitations. It proposes a new delayed capture methodology as a low overhead soft error detection technique. Delayed capture methodology is an enhancement of the Razor flip-flop methodology. In the delayed capture methodology, the parity for a set of flip-flops is calculated at their inputs and outputs. The input parity is latched on a second clock, which is delayed with respect to the functional clock by more than the soft error pulse width. It requires an extra flip-flop for each set of flip-flops. On the other hand, in the Razor flip-flop methodology an additional flip-flop is required for every functional flip-flop. Due to the skew in the clocks, either the parity flip-flop or the functional flip-flop will capture the effect of transient, and hence by comparing the output parity and latched input parity an error can be detected. Fault injection experiments are performed to evaluate the bneefits and limitations of the proposed approach. The limitations include soft error detection escapes and lack of error correction capability. Different cases of soft error detection escapes are analyzed. They are attributed mainly to a Single Event Upset (SEU) causing multiple flip-flops within a group to be in error. The error space due to SEUs is analyzed and an intelligent flip-flop grouping method using graph theoretic formulations is proposed such that no SEU can cause multiple flip-flops within a group to be in error. Once the error occurs, leaving the correction aspects to the application may not be desirable. The proposed delayed capture methodology is extended to replace parity codes with codes having higher redundancy to enable correction. The hardware overhead due to the proposed methodology is analyzed and an area savings of about 15% is obtained when compared to an existing soft error mitigation methodology with equivalent coverage. The impact of different derating factors in determining the hardware overhead due to the soft error mitigation methodology is then analyzed. We have considered electrical derating and timing derating information for the evaluation purpose. The area overhead of the circuit with implementation of delayed capture methodology, considering different derating factors standalone and in combination is then analyzed. Results indicate that in different circuits, either a combination of these derating factors yield optimal results, or each of them considered standalone. This is due to the dependency of the solution on the heuristic nature of the algorithms used. About 23% area savings are obtained by employing these derating factors for a more optimal grouping of flip-flops. A new paradigm of hardware software co-design for reliability is finally proposed. This is based on application derating in which the application / firmware code is profiled to identify the critical components which must be guarded from soft errors. This identification is based on the ability of the application software to tolerate certain errors in hardware. An algorithm to identify critical components in the control logic based on fault injection is developed. Experimental results indicated that for a safety critical automotive application, only 12% of the sequential logic elements were found to be critical. This approach provides a framework for investigating how software methods can complement hardware methods, to provide a reduced hardware solution for soft error mitigation.

Using non-experimental descriptive exploratory survey, this study sought to find out factors associated with delayed entry into HIV medical care among HIV positive people who are aware of their status. A quantitative design was used and a structured questionnaire was used as the data collection instrument. Respondents were patients in a hospital’s Opportunistic Infection Department whose hospital records indicated that they were HIV positive during the time of the study. The study found out that as much as 71.6% (n =43) first entered HIV medical care more than 12 months after testing HIV positive while 40% (n = 24) did so as a result of illness. Low education levels, unemployment and being single are associated with delayed entry into HIV medical care. A percentage of the population uses and trusts non-biomedical approaches to dealing with HIV/AIDS. Being diagnosed HIV positive is therefore not necessarily a strong reason enough for one to immediately enter into medical care. Intensive health education needs to be done at work places, health facilities, schools, through print and electronic media, churches and other community settings to equip the population with knowledge of the advantages of early entry into HIV care. / Health Studies / M.A. (Public Health)

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Please see fulltext for abstract. / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming.

Premature concrete deterioration due to alkali-silica reaction (ASR) and delayed ettringite formation (DEF) is a significant problem all over the world. In cases where these mechanisms were not initially prevented, mitigation is critical to halt expansion and cracking. The main objectives of the research presented herein were to study the effect of ambient relative humidity (RH) on rates of concrete expansion, to determine RH thresholds below which expansion due to ASR and/or DEF may be suppressed, and to evaluate coatings intended to lower the internal RH of concrete and thus minimize future potential for damage. Results from testing showed that the RH threshold for ASR was below 82%, the RH threshold for DEF was below 92%, and the RH threshold for combined ASR and DEF could be about 83% for the materials tested. Furthermore, it was shown that some coatings are effective in reducing ASR- and DEF-related expansion by lowering the internal RH of concrete. / text

The thesis describes theoretical and experimental studies on the chaotic behaviour of a peak current-mode controlled boost converter, a parallel two-module peak current-mode controlled DC-DC boost converter, and a peak current-mode controlled power factor correction (PFC) boost converter. The research concentrates on converters which do not have voltage control loops, since the main interest is in the intrinsic mechanism of chaotic behaviour. These converters produce sub-harmonics of the clock frequency at certain values of the reference current I[ref] and input voltage V[in], and may behave in a chaotic manner, whereby the frequency spectrum of the inductor becomes continuous. Non-linear maps for each of the converters are derived using discrete time modelling and numerical iteration of the maps produce bifurcation diagrams which indicate the presence of subharmonics and chaotic operation. In order to check the validity of the analysis, MATLAB/SIMULINK models for the converters are developed. A comparison is made between waveforms obtained from experimental converters, with those produced by the MATLAB/SIMULINK models of the converters. The experimental and theoretical results are also compared with the bifurcation points predicted by the bifurcation diagrams. The simulated waveforms show excellent agreement, with both the experimental waveforms and the transitions predicted by the bifurcation diagrams. The thesis presents the first application of a delayed feedback control scheme for eliminating chaotic behaviour in both the DC-DC boost converter and the PFC boost converter. Experimental results and FORTRAN simulations show the effectiveness and robustness of the scheme. FORTRAN simulations are found to be in close agreement with experimental results and the bifurcation diagrams. A theoretical comparison is made between the above converters controlled using delayed feedback control and the popular slope compensation method. It is shown that delayed feedback control is a simpler scheme and has a better performance than that for slope compensation.

Five humans were exposed to a matching to sample task in which the delay (range = 0 to 32 seconds) between sample stimulus offset and comparison onset was manipulated across conditions. Auditory stimuli (1” tone) and arbitrary symbols served as sample stimuli for three (S1, S2, S3) and two (S4 and S5) subjects, respectively. Uppercase English letters (S, M, and N) served as comparison stimuli for all subjects. Results show small but systematic effects of the retention interval on accuracy and latency to selection of comparison stimuli. The results fail to show a difference between subjects exposed to auditory and visual sample stimuli. Some reasons for the failure to note a difference are discussed.

La Réaction Sulfatique Interne (RSI) est une pathologie du béton pouvant affecter les matériaux soumis à un échauffement au-delà de 65°C. Elle consiste en une formation d'ettringite dans le matériau durci et conduit à son gonflement. Il s'en suit une fissuration et une dégradation des performances mécaniques pouvant poser des problèmes d'intégrité structurelle à l'instar de la Réaction Alcali-Granulat (RAG) à laquelle elle est fréquemment couplée in situ. Lorsqu'un ouvrage est atteint, il convient de poser un diagnostic, évaluer son aptitude au service, prédire son évolution et mettre en uvre des méthodes de réparation. Ceci nécessite une compréhension fine des effets de la RSI à l'échelle microscopique et à l'échelle de l'ouvrage. De nombreuses études expérimentales et théoriques ont été menées pour déterminer les mécanismes mis en uvre et les paramètres influençant la RSI. Toutefois, la complexité des phénomènes rend délicate la transposition de ces connaissances à l'échelle de la structure. Les approches macroscopiques semblent donc plus adaptées à ce type de problème. Pour mettre au point ces approches, il est nécessaire de comprendre en détail les effets de la pathologie à l'échelle du matériau et de la structure. Cette thèse décrit les résultats d'une étude de laboratoire basée sur des essais sur éprouvettes pour caractériser les couplages entre les gonflements et l'humidité, la température et l'état de contraintes. Ces travaux ont également été l'occasion d'étudier les couplages entre RAG et RSI. En parallèle, des suivis dimensionnels et hydriques de poutres soumises à des conditions d'exposition à l'humidité contrôlées ont permis de constituer une base de données des effets structurels de la RSI. La confrontation de ces essais menés conjointement à l'échelle du matériau et de la structure fournit des données permettant de mettre au point des méthodes de re-calcul des ouvrages et de les valider en confrontant leurs prédictions aux résultats expérimentaux / Delayed Ettringite Formation (DEF) is a reaction that can affect concretes exposed to temperatures higher than 65°C. The corresponding formation of ettringite in the hardened material leads to swellings, cracking and decrease of the mechanical properties. Thus it gives serious concern in terms of structural integrity and serviceability. DEF is often coupled with Alkali-Aggregate Reaction (AAR) in the field. For a structure manager, it is necessary to be able to diagnose the reaction, to assess the serviceability of the structure, to predict its evolution and to repair it. To reach these objectives, it is necessary to understand DEF effects both at the microscopic scale and the structure scale. In the literature, a lot of theoretical and experimental researches have been reported and deal mainly with the chemo-physical mechanisms. These results emphasize the complexity of the microscopic features of DEF and thus can hardly be used to model its structural effects. Thus, macroscopic approaches seem to be more adapted. To develop such approaches, it is necessary to understand the effect of the deleterious process at the scale of the material and of the structure. In this context, this research proposes to quantify the couplings between DEF-induced swellings and moisture, temperature and mechanical loadings thanks to material tests on concrete cylinders. The couplings between DEF and AAR are as well investigated. Moreover the monitoring of dimensions and water content of concrete beams is also performed while being exposed to various controlled water supply conditions. The corresponding results provide a database useful to analyse quantitatively the mechanical effects of DEF (for the material and for the structures) and to validate the numerical models by comparing their predictions to the experimental behaviour