154 research outputs found
A Qualitative Evaluation of Volunteers' Experiences in a Phase I/II HIV Vaccine Trial in Tanzania.
No full textEvaluating experiences of volunteers in an HIV vaccine trial will be useful for the conduct of future trials. The purpose of this study among volunteers who participated in a phase I/II HIV vaccine trial in Dar es Salaam, Tanzania was to assess what characterized their experiences during the trial. We conducted four focus group discussions with 35 out of the 60 individuals (women and men) after the five scheduled vaccinations. An interpretive description approach was applied to data analysis. As a result of the trial interventions, both men and women gained confidence in their own abilities to have safer, less risky sexual behaviour. The participants experienced the trial as a way of accessing free [insured] medical services. Most of the men said they had gone from self-medication to professional medical consultation. Despite these benefits, the participants faced various challenges during the trial. Such challenges included mistrust of the trial shown by health care providers who were not connected to the trial and discouragement from friends, colleagues and family members who questioned the safety of the trial. However, they managed to cope with these doubts by using both personal and trial related interventions. We found that during the phase I/II HIV vaccine trial, participants had both the opportunities and the ability to cope with the doubts from the surrounding community. Follow up visits enhanced the opportunities and individuals' abilities to cope with the doubts during the trial. Understanding this discourse may be useful for the trial implementers when designing future trials.\ud
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Motivations and deterrents to take part in an HIV vaccine trial : experiences from study participants in Dar es Salaam, Tanzania
No full textBackground: As HIV infection continues to be a public health problem, development of an effective preventive HIV vaccine is a priority. For the ultimate development of an AIDS vaccine, clinical trials are being conducted throughout the world. However, the process of developing the vaccine does not only depend on identification of suitable trial candidates, but also requires knowledge of incentives to participate in the community where the trial is being conducted. Therefore, the studies presented in this thesis are components of a HIV/AIDS and HIV vaccine trial project in Dar es Salaam, Tanzania to address motivations and deterrents of participating in an HIV vaccine trial.Aim: To examine the motivations and deterrents for participating in preventive HIV vaccine trials.Methods: Data were collected from participants and volunteers who were considered for participation or participated in a phase I/II HIV vaccine trial. Four studies with different designs were conducted. In Study I, a semi-structured interview administered questionnaire was used to assess willingness to volunteer for a phase I/II HIV vaccine trial. A convenience sample of 329 individuals from the police force cohort was recruited for the study in 2005-2006. In Study II, focus group discussions were conducted to explore factors that would influence participation in an HIV vaccine trial among members of the police force in 2006-2007. In Study III, face-to-face interviews were used to identify reasons for declining to enrol in an HIV vaccine trial among those who agreed to enrol at the start and were randomized for the trial in 2007-2009. In Study IV, we used focus group discussions to evaluate the experiences of those who participated in the phase I/II trial in 2009.Results: Willingness to volunteer for an HIV vaccine trial was associated with intention to tell others, positive outcome of the trial, personal decision and expectation of obtaining protection against HIV infection. Participation in an HIV vaccine trial would be negatively influenced by sexual partners, friends, family members, relatives or parents (significant others) and fear of vaccine side-effects. Personal fears and negative influences from significant others were the main reasons for declining to enrol in an HIV vaccine trial. Despite the negative comments from significant others, volunteers in the HIV vaccine trial managed to stay on until the end of the trial as a result of personal decision and trial-related interventions.Conclusion: Personal decision is both a motivation to participate in an HIV vaccine trial and a reason to stay on until the end of trial. On the contrary, significant others are the deterrents to participation in the HIV vaccine trial and the reason for declining to enrol in the HIV vaccine trial. Awareness of these issues before trial implementation may help to maximize resource use and enhance retention of those who volunteer in the HIV vaccine trials.List of scientific papersI. Tarimo, EAM., Thorson, A., Bakari, M., Mwami, J., Sandstrom, E., and Kulane, A. Willingness to volunteer in a phase I/II HIV vaccine trial: a study among police officers in Dar es Salaam, Tanzania. Global Health Action. 2009, 2. https://doi.org/10.3402/gha.v2i0.1953 II. Tarimo, EAM., Thorson, A., Kohi, TW., Mwami, J., Bakari, M., Sandstrom, E., and Kulane, A. Balancing collective responsibility, individual opportunities and risks: A qualitative study on how police officers reason around volunteering in an HIV vaccine trial in Dar es Salaam, Tanzania. BMC Public Health. 2010.10: 292. https://doi.org/10.1186/1471-2458-10-292 III. Tarimo, EAM., Thorson, A., Kohi, TW., Bakari, M., Mhalu, F., and Kulane, A. Reasons for declining to enrol in a phase I and II HIV vaccine trial after randomization among eligible volunteers in Dar es Salaam, Tanzania. PLoS One. 2011.6(2): e14619. https://doi.org/10.1371/journal.pone.0014619 IV. Tarimo, EAM., Thorson, A., Kohi, TW., Bakari, M., Mhalu, F., Sandstrom, E., and Kulane, A. A qualitative evaluation of volunteers' experiences in a phase I/II HIV vaccine trial in Tanzania. [Manuscript]</p
Motivations and deterrents to take part in an HIV vaccine trial : experiences from study participants in Dar es Salaam, Tanzania [Elektronisk resurs]
No full textBackground: As HIV infection continues to be a public health problem, development of an effective preventive HIV vaccine is a priority. For the ultimate development of an AIDS vaccine, clinical trials are being conducted throughout the world. However, the process of developing the vaccine does not only depend on identification of suitable trial candidates, but also requires knowledge of incentives to participate in the community where the trial is being conducted. Therefore, the studies presented in this thesis are components of a HIV/AIDS and HIV vaccine trial project in Dar es Salaam, Tanzania to address motivations and deterrents of participating in an HIV vaccine trial. Aim: To examine the motivations and deterrents for participating in preventive HIV vaccine trials. Methods: Data were collected from participants and volunteers who were considered for participation or participated in a phase I/II HIV vaccine trial. Four studies with different designs were conducted. In Study I, a semi-structured interview administered questionnaire was used to assess willingness to volunteer for a phase I/II HIV vaccine trial. A convenience sample of 329 individuals from the police force cohort was recruited for the study in 2005-2006. In Study II, focus group discussions were conducted to explore factors that would influence participation in an HIV vaccine trial among members of the police force in 2006-2007. In Study III, face-to-face interviews were used to identify reasons for declining to enrol in an HIV vaccine trial among those who agreed to enrol at the start and were randomized for the trial in 2007-2009. In Study IV, we used focus group discussions to evaluate the experiences of those who participated in the phase I/II trial in 2009. Results: Willingness to volunteer for an HIV vaccine trial was associated with intention to tell others, positive outcome of the trial, personal decision and expectation of obtaining protection against HIV infection. Participation in an HIV vaccine trial would be negatively influenced by sexual partners, friends, family members, relatives or parents (significant others) and fear of vaccine side-effects. Personal fears and negative influences from significant others were the main reasons for declining to enrol in an HIV vaccine trial. Despite the negative comments from significant others, volunteers in the HIV vaccine trial managed to stay on until the end of the trial as a result of personal decision and trial-related interventions. Conclusion: Personal decision is both a motivation to participate in an HIV vaccine trial and a reason to stay on until the end of trial. On the contrary, significant others are the deterrents to participation in the HIV vaccine trial and the reason for declining to enrol in the HIV vaccine trial. Awareness of these issues before trial implementation may help to maximize resource use and enhance retention of those who volunteer in the HIV vaccine trials
Molecule Statistical Thermodynamics Simulation of Nanoindentation of Single Crystal Copper with EAM Potential
No full textThe quasistatic nanoindentation process of a spherical indenter in a single crystal copper is investigated with the molecular statistical thermodynamics (MST) method based on the embedded atom method (EAM) potential. The indentation modulus obtained in the MST simulation is 129.9GPa, which agrees well with the theoretical prediction (129GPa). In the elastic regime, the obtained maximum displacement of the indenter is two times the contact depth and the contact area is qualitatively proportional to the contact depth, which agrees well with Hertzian elastic theory of contact. The MST simulation can reproduce the nucleation of dislocation as well. Moreover, the efficiency of the MST method is about 8 times higher than that of traditional MD simulations
The Perceptions on Male Circumcision as a Preventive Measure Against HIV Infection and Considerations in Scaling up of the Services: A Qualitative Study Among Police Officers in Dar es Salaam, Tanzania.
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In recent randomized controlled trials, male circumcision has been proven to complement the available biomedical interventions in decreasing HIV transmission from infected women to uninfected men. Consequently, Tanzania is striving to scale-up safe medical male circumcision to reduce HIV transmission. However, there is a need to investigate the perceptions of male circumcision in Tanzania using specific populations. The purpose of the present study was to assess the perceptions of male circumcision in a cohort of police officers that also served as a source of volunteers for a phase I/II HIV vaccine (HIVIS-03) trial in Dar es Salaam, Tanzania. In-depth interviews with 24 men and 10 women were conducted. Content analysis informed by the socio-ecological model was used to analyze the data. Informants perceived male circumcision as a health-promoting practice that may prevent HIV transmission and other sexually transmitted infections. They reported male circumcision promotes sexual pleasure, confidence and hygiene or sexual cleanliness. They added that it is a religious ritual and a cultural practice that enhances the recognition of manhood in the community. However, informants were concerned about the cost involved in male circumcision and cleanliness of instruments used in medical and traditional male circumcision. They also expressed confusion about the shame of undergoing circumcision at an advanced age and pain that could emanate after circumcision. The participants advocated for health policies that promote medical male circumcision at childhood, specifically along with the vaccination program. The perceived benefit of male circumcision as a preventive strategy to HIV and other sexually transmitted infections is important. However, there is a need to ensure that male circumcision is conducted under hygienic conditions. Integrating male circumcision service in the routine childhood vaccination program may increase its coverage at early childhood. The findings from this investigation provide contextual understanding that may assist in scaling-up male circumcision in Tanzania.\u
Balancing Collective Responsibility, Individual Opportunities and Risks: A Qualitative Study on How Police Officers Reason Around Volunteering in an HIV Vaccine Trial in Dar es Salaam, Tanzania.
No full textResults from HIV vaccine trials on potential volunteers will contribute to global efforts to develop an HIV vaccine. The purpose of this study among police officers in Dar es Salaam, Tanzania, was to explore the underlying reasons that induce people to enrol in an HIV vaccine trial.\ud
We conducted discussions with eight focus groups, containing a total of 66 police officers. The information collected was analyzed using interpretive description. The results showed that participants were motivated to participate in the trial by altruism, and that the participants experienced some concerns about their participation. They stated that altruism in the fight against HIV infection was the main reason for enrolling in the trial. However, young participants were seriously concerned about a possible loss of close relationships if they enrolled in the HIV vaccine trial. Both men and women feared the effect of the trial on their reproductive biology, and they feared interference with pregnancy norms. They were unsure about risks such as the risks of acquiring HIV infection and of suffering physical harm, and they were unsure of the intentions of the researchers conducting the trial. Further, enrolling in the trial required medical examination, and this led some participants to fear that unknown diseases would be revealed. Other participants, however, saw an opportunity to obtain free health services.\ud
We have shown that specific fears are important concerns when recruiting volunteers to an HIV vaccine trial. More knowledge is needed to determine participants' views and to ensure that they understand the conduct of the trial and the reasons it is being carried out
A Qualitative Study of Perceived Risk for HIV Transmission among Police Officers in Dar es Salaam, Tanzania.
No full textUnderstanding people's views about HIV transmission by investigating a specific population may help to design effective HIV prevention strategies. In addition, knowing the inherent sexual practices of such a population, as well as the risky circumstances that may facilitate HIV transmission, is crucial for the said strategies to become effective. In this article, we report how police officers in Dar es Salaam, Tanzania, perceived the problem of HIV and AIDS in their local context, particularly in relation to unsafe sexual practices. The study was done with the view to recommending ways by which HIV transmission could be minimised within the police force. The study was conducted among members of the police force in Dar es Salaam, Tanzania. Eight focus group discussions (FGDs) were conducted, with a total of 66 participants who were mixed in terms of age, gender, and marital status. Some of these were caregivers to patients with AIDS. Data were analysed using the interpretive description approach. The participants believed that both individual sexual behaviour and work-related circumstances were sources of HIV infection. They also admitted that they were being tempted to engage in risky sexual practices because of the institutional rules that prohibit officers from getting married during their training and for three years after. Nevertheless, as members of the Police Force, they stressed the fact that the risky sexual behaviour that exposes them to HIV is not limited to the force; it is rather a common problem that is faced by the general population. However, they complained, the nature of their job exposes them to road accident victims, subjecting them further to possible infection, especially when they have to handle these road accident casualties without proper protective gear. Individual sexual behaviour and job-related circumstances are worth investigating if proper advice is to be given to the police regarding HIV prevention strategies. In order to improve the lives of these police officers, there is a need to review the existing institutional rules and practices to accommodate individual sexual needs. In addition, improving their working environment may minimize the risk of HIV transmission from handling casualties in emergency situations
Functional and field performance of epoxy asphalt technology-state-of-the-art
No full textThere is an increasing demand for high strength and more durable materials in the asphalt technology market. In response to the demand, epoxy asphalt mixture (EAM) is one relatively new technology for use as a paving material in flexible pavements. There are various research works carried out on the laboratory and field performance of EAM. However, comprehensive research covering functional and field (F&F) performance of EAM is lacking. The main purpose of this review is to bridge this gap via the analysis of the functional properties of EAM. Consequently, the field performance of EAM in different case studies is reviewed and the serviceability of EAM in various transportation infrastructure is investigated. This paper also reviews the life cycle cost and maintenance of EAM. The major findings indicate that EAM shows superior F&F performance compared to the traditional hot and warm asphalt mixture. Additionally, the use of EAM is beneficial in the structure of pavements in tunnels and on bridge decks. In conclusion, the higher F&F performance of EAM supports the development of better performing pavements for various applications
Open Data in Engineering Asset Management: A Case Study into the possibilities and challenges of using Open Data in Engineering Asset Management
No full textThe use of Open Data (OD) in an Engineering Asset Management (EAM) context is largely unexplored. Even though research into OD is moving forward, this knowledge is not fully usable in EAM because of the complexity and the specific characteristics of EAM. The research is centred around the case study that has taken place. As input for the case study, a literature review has been conducted to summarize and analyse the existing knowledge of OD and EAM. This created a starting point for the case study. A case about the traffic situation around the IJsselbruggen and the VIA15 project (A12) has been selected to research the possibilities to use OD with the goal to evaluate the current traffic measures and investigate the possibilities for Data-Driven Decision Making (DDDM). The combined results of the literature review and the case study have been reviewed by a group of experts in an expert workshop session. Besides there critical opinion about the research, the experts where also asked about their view on the use of OD in the EAM sector.Engineering and Policy Analysi
GeSn/SiGeSn Multiple-Quantum-Well Electroabsorption Modulator With Taper Coupler for Mid-Infrared Ge-on-Si Platform
No full textWe propose a taper coupler electroabsorption modulator (EAM) composed of GeSn/SiCeSn multiple-quantum-well (MQW) on Ge-on-Si platform for mid-infrared (2 mu m) integrated optical active devices. The epitaxial design is performed by calculating the absorption spectra of GeSn/SiGeSn MQW using many-body theory to investigate the extinction characteristics of GeSn MQW waveguides. Two types of taper couplers are considered for connecting Ge-rib waveguide and GeSn-MQW-highmesa waveguide efficiently. One is an adiabatic taper coupler (ATC) type EAM and it is useful for thin Ge-buffer structure in terms of the extinction ratio. Another is a resonant taper coupler (RTC) type EAM and it is superior to ATC type EAM for thick Ge-buffer. It is confirmed that RTC type EAM can obtain the high extinction characteristics with low-loss and shorter device length (6.87 dB, -3.97 dB, and 215 mu m) compared with conventional ATC type EAM for thick Ge-buffer (5.67 dB, -4.9 dB, and 340 mu m)
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