Student experiences of virtual reality - a case study in learning special relativity

We present a study of student learning through the use of virtual reality. A software package is used to introduce concepts of special relativity to students in a game-like environment where users experience the effects of travelling at near light speeds. From this new perspective, space and time are significantly different to that experienced in everyday life. The study explores how students have worked with this environment and how these students have used this experience in their study of special relativity. A mixed method approach has been taken to evaluate the outcomes of separate implementations of the package at two universities. Students found the simulation to be a positive learning experience and described the subject area as being less abstract after its use. Also, students were more capable of correctly answering concept questions relating to special relativity, and a small but measurable improvement was observed in the final exam

Family planning methods among women in a vaginal microbicide feasibility study in rural KwaZulu-Natal, South Africa

This study investigated contraceptive use among women in rural KwaZulu-Natal, South Africa. Of 866 sexually active women not intending pregnancy and screened for a microbicide feasibility study, 466 (54%) reported currently using modern contraceptives: injectables (31%), condoms (12%), sterilization (60%) and pills (4%). Multivariable logistic regression analyses revealed statistically significantly higher odds of current contraceptive use among married vs. engaged/unmarried women (aOR 1.64), multiparous vs. nulliparous (aOR 4.45) and women who completed secondary education or above vs. primary or less (aOR 1.64). Significantly lower odds of use were observed among women aged 40+ vs. age 15-19 (aOR 0.38). Age, marital status, education level and parity were associated with different contraceptive method choices. Among 195 women followed longitudinally for 9 months, contraceptive use increased significantly from 56% to 70%, largely due to increased condom use (15% to 28%). Results highlight the importance of integrating family planning and HIV/STI prevention counseling and informing promotion of further contraceptive uptake among women not intending pregnancy

Informed consent comprehension in African research settings

ObjectivePrevious reviews on participants' comprehension of informed consent information have focused on developed countries. Experience has shown that ethical standards developed on Western values may not be appropriate for African settings where research concepts are unfamiliar. We undertook this review to describe how informed consent comprehension is defined and measured in African research settings.MethodsWe conducted a comprehensive search involving five electronic databases: Medline, Embase, Global Health, EthxWeb and Bioethics Literature Database (BELIT). We also examined African Index Medicus and Google Scholar for relevant publications on informed consent comprehension in clinical studies conducted in sub-Saharan Africa. 29 studies satisfied the inclusion criteria; meta-analysis was possible in 21 studies. We further conducted a direct comparison of participants' comprehension on domains of informed consent in all eligible studies.ResultsComprehension of key concepts of informed consent varies considerably from country to country and depends on the nature and complexity of the study. Meta-analysis showed that 47% of a total of 1633 participants across four studies demonstrated comprehension about randomisation (95% CI 13.9–80.9%). Similarly, 48% of 3946 participants in six studies had understanding about placebo (95% CI 19.0–77.5%), while only 30% of 753 participants in five studies understood the concept of therapeutic misconception (95% CI 4.6–66.7%). Measurement tools for informed consent comprehension were developed with little or no validation. Assessment of comprehension was carried out at variable times after disclosure of study information. No uniform definition of informed consent comprehension exists to form the basis for development of an appropriate tool to measure comprehension in African participants.ConclusionsComprehension of key concepts of informed consent is poor among study participants across Africa. There is a vital need to develop a uniform definition for informed consent comprehension in low literacy research settings in Africa. This will be an essential step towards developing appropriate tools that can adequately measure informed consent comprehension. This may consequently suggest adequate measures to improve the informed consent procedure.ObjectifLes normes éthiques élaborées selon les valeurs occidentales ne sont peut-être pas appropriées au contexte africain où les concepts de recherche ne sont pas familiers. Cette revue décrit comment la compréhension du consentement éclairé est définie et mesurée dans les cadres de recherche africains.MéthodesDes recherches ont été effectuées sur Medline, Embase, Global Health, EthxWeb, base de données de la Bioéthique Littérature, Index Medicus African et Google Scholar pour des publications pertinentes sur la compréhension du consentement éclairé dans les études cliniques menées en Afrique sub-saharienne. 29 études répondaient aux critères d'inclusion; une méta-analyse a été possible pour 21 études. La compréhension des participants sur les domaines du consentement éclairé dans toutes les études admissibles a été comparée directement.RésultatsLa compréhension des concepts clés du consentement éclairé varie considérablement selon les pays et dépend de la nature et de la complexité de l’étude. La méta-analyse a montré que 47% des participants ont compris la randomisation (IC95%: 13,9 - 80,9%), 48% ont compris le placebo (IC95%: 19,0 - 77,5%), 30% ont compris le concept de méprise thérapeutique (IC95%: 4,6 - 66,7%). Les outils de mesure de la compréhension du consentement éclairé étaient développés avec peu ou pas de validation.ConclusionsLa compréhension des concepts clés du consentement éclairé est faible en Afrique. Il y a une nécessité vitale d’élaborer une définition uniforme pour la compréhension du consentement éclairé dans les cadres de recherche avec un faible niveau d'alphabétisation en Afrique.ObjetivoLos estándares éticos desarrollados basándose en valores occidentales podrían no ser apropiados para emplazamientos Africanos en donde los conceptos de investigación no son familiares. En esta revisión se describe como la comprensión del consentimiento informado se define y mide en un centro de investigación Africano.MétodosSe buscaron publicaciones relevantes sobre la comprensión del consentimiento informado en estudios clínicos en África subsahariana en Medline, Embase, Global Health, EthxWeb, Bioethics Literature Database, African Index Medicus y Google Scholar. 29 estudios satisfacían los criterios de inclusión y el metaanálisis era posible para 21. La comprensión del consentimiento informado por parte de los participantes se comparó directamente en todos los estudios elegibles.ResultadosLa comprensión de conceptos claves del consentimiento informado varió de forma considerable entre países, y dependía de la naturaleza y de la complejidad del estudio. El meta-análisis mostró que un 47% entendía la aleatorización (IC 95% 13.9-80.9%); un 48% entendía el placebo (IC 95% 19.0-77.5%); y un 30% entendió el concepto terapéutico errado (IC 95% 4.6-66.7%). Las herramientas para medir la comprensión del consentimiento informado se desarrollaron con poca o ninguna validación.ConclusionesEn África, la comprensión de conceptos claves del consentimiento informado es pobre. Existe una necesidad vital de desarrollar una definición uniforme para la comprensión del consentimiento informado en lugares con bajos niveles de alfabetización en África

Work hardening behavior in a steel with multiple TRIP mechanisms

Transformation induced plasticity (TRIP) behavior was studied in steel with composition Fe-0.07C-2.85Si-15.3Mn-2.4Al-0.017N that exhibited two TRIP mechanisms. The initial microstructure consisted of both {\epsilon}- and {\alpha}-martensites with 27% retained austenite. TRIP behavior in the first 5% strain was predominately austenite transforming to {\epsilon}-martensite (Stage I), but upon saturation of Stage I, the {\epsilon}-martensite transformed to {\alpha}-martensite (Stage II). Alloy segregation also affected the TRIP behavior with alloy rich regions producing TRIP just prior to necking. This behavior was explained by first principle calculations that revealed aluminum significantly affected the stacking fault energy in Fe-Mn-Al-C steels by decreasing the unstable stacking fault energy and promoting easy nucleation of {\epsilon}-martensite. The addition of aluminum also raised the intrinsic stacking fault energy and caused the {\epsilon}-martensite to be unstable and transform to {\alpha}-martensite under further deformation. The two stage TRIP behavior produced a high strain hardening exponent of 1.4 and led to ultimate tensile strength of 1165 MPa and elongation to failure of 35%.Comment: submitted to Met. Mater. Trans. A manuscript E-TP-12-953-

Paper Session III-C - A Portable MBA Guide to the Commercialization of Space

This paper adopts reputable analytical techniques for identifying near and long term strategic success factors in the space telecommunications industry. Main conclusions of an industry analysis point to leverage attainable through moving quickly and massively, establishing large market share and production volumes, and getting unit costs down. However, limitations in the efficiency of launch vehicles, and the capacity of the global launch infrastructure, will continue to pace progress. It is then proffered that launch costs per pound might not be the best strategic metric of progress; rather, that more strategically important cost-reduction opportunities might lie in improving the overall characteristics of whole value chains viewed as systems, aimed at reducing the cost per service delivered over whole life cycles

General perturbation method for satellite constellation deployment using nodal precession

The dawn of "New Space" in recent years is changing the landscape of the space industry. In particular, the shift to smaller satellites, requiring shorter development time s and using off-the-shelf-components and standardized buses, has led to a continuing reduction in spacecraft cost. However, launch costs remain extremely high and frequently dominate the total mission cost. Additionally, many small satellites are designed to operate as part of a larger constellation, but traditional launch methods require a difference dedicated launch for each orbit plane to be populated. This need for multiple costly launches can stifle, and even prohibit, some missions requiring numerous orbit planes as the launch cost increases beyond what can be justified for the mission. As of 2014, most smallsats, including CubeSats, have been launched on opportunistic ‘rideshare’ or ‘piggy-back’ launches, in which the spacecraft shares its launch with other craft, often as a secondary payload. This has the advantage of providing a cheaper launch but restricts the operator’s choice of orbit, which will affect the system performance

Paper Session I-B - The Competitive Advantage of Florida Firms in Aerospace

This paper provides an analysis of the sustainable competitive advantage of Florida firms as they compete in the aviation/aerospace sector, with special emphasis on the space industry. First, the theory of comparative advantage is reviewed, as well as its relevance to the theory of firm-level competitive advantage. Next, after a brief review of local history, recent actions taken by Florida policy makers will be reviewed to serve as “grist for the mill” of economic theory. Florida’s actions in light of theory will then be framed and implications offere

Ethnic coalitions and the logic of political survival in authoritarian regimes

Why do authoritarian governments exclude ethnic groups if this jeopardizes their regime survival? We generalize existing arguments that attribute exclusion dynamics to ethnic coalition formation. We argue that a mutual commitment problem, between the ethnic ruling group and potential coalition members, leads to power-balanced ethnic coalitions. However, authoritarian regimes with institutions that mitigate credible commitment problems facilitate the formation of coalitions that are less balanced in power. We test our arguments with a k-adic conditional logit approach, using data on ethnic groups and their power status. We demonstrate that in autocracies, the ruling ethnic group is more likely to form and maintain coalitions that balance population sizes among all coalition members. Furthermore, we provide evidence that the extent to which balancing occurs is conditional on authoritarian regime type

Time to eligibility for antiretroviral therapy in adults with CD4+ cell count >500 cells/µl in rural KwaZulu-Natal, South Africa

ObjectivesUnderstanding of progression to antiretroviral therapy (ART) eligibility and associated factors remains limited. The objectives of this analysis were to determine the time to ART eligibility and to explore factors associated with disease progression in adults with early HIV infection.MethodsHIV-infected adults (??18 years old) with CD4 cell count >?500 cells/?l were enrolled in the study at three primary health care clinics, and a sociodemographic, behavioural and partnership-level questionnaire was administered. Participants were followed 6-monthly and ART eligibility was determined using a CD4 cell count threshold of 350 cells/?l. Kaplan???Meier and Cox proportional hazard regression modelling were used in the analysis.ResultsA total of 206 adults contributed 381 years of follow-up; 79 (38%) reached the ART eligibility threshold. Median time to ART eligibility was shorter for male patients (12.0 months) than for female patients (33.9 months). Male sex [adjusted hazard ratio (aHR) 3.13; 95% confidence interval (CI) 1.82–5.39], residing in a household with food shortage in the previous year (aHR 1.58; 95% CI 0.99–2.54), and taking nutritional supplements in the first 6 months after enrolment (aHR 2.06; 95% CI 1.11–3.83) were associated with shorter time to ART eligibility. Compared with reference CD4 cell count????559 cells/?l, higher CD4 cell count was associated with longer time to ART eligibility [aHR 0.46 (95% CI 0.25–0.83) for CD4 cell count 560–632 cells/?l; aHR 0.30 (95% CI 0.16–0.57) for CD4 cell count 633–768 cells/?l; and aHR 0.17 (95% CI 0.08–0.38) for CD4 cell count?>?768 cells/?l].ConclusionsOver one in three adults with CD4 cell count?>?500 cells/?l became eligible for ART at a CD4 cell count threshold of 350 cells/?l over a median of 2 years. The shorter time to ART eligibility in male patients suggests a possible need for sex-specific pre-ART care and monitoring strategies

Recurrent child mortality risks and parity transition in Nigeria

BackgroundFertility rates remain persistently high in Nigeria, with little difference across socioeconomic groups. While the desire for large family size is culturally rooted, there is little understanding of how repeated child mortality experiences influence fertility behaviour and parity transition in Nigeria.MethodsUsing birth history data from the 2013 Nigeria Demographic and Health Survey (NDHS), we applied life table techniques and proportional-hazard regression model to explore the effect of child survival experience on parity transitions. We hypothesize that a woman with one or more child death experience is at elevated risk of progressing towards higher parities.ResultsOur findings show that child mortality is concentrated among mothers living in deprived conditions especially in rural areas of the northern part of Nigeria and among those with little or no education and, among those belonging to Hausa/Fulani ethnicity and Islam religion. Mothers with repeated experience of child deaths were significantly at a higher rate of progressing to higher parities than their counterparts (HR: 1.45; 95% CI: 1.31–1.61), when adjusted for relevant biological and socio-demographic characteristics.ConclusionRecurrent experience of child deaths exacerbates the risks to higher parity transition. Interventions aimed at reducing fertility in Nigeria should target promoting child survival and family planning concurrently