Heat flux sensor research and development: The cool film calorimeter

The goal was to meet the measurement requirement of the NASP program for a gauge capable of measuring heat flux into a 'typical' structure in a 'typical' hypersonic flight environment. A device is conceptually described that has fast response times and is small enough to fit in leading edge or cowl lip structures. The device relies heavily on thin film technology. The main conclusion is the description of the limitations of thin film technology both in the art of fabrication and in the assumption that thin films have the same material properties as the original bulk material. Three gauges were designed and fabricated. Thin film deposition processes were evaluated. The effect of different thin film materials on the performance and fabrication of the gauge was studied. The gauges were tested in an arcjet facility. Survivability and accuracy were determined under various hostile environment conditions

On the Performance of Passivr TMDs in Reducing the Damage in 2-D Concrete Structural Models

AbstractPozzolanic materials, either naturally occurring or artificially made, have long been in practice since the early civilization. In recent years, the utilisation of pozzolanic materials in concrete construction has become increasingly widespread, and this trend is expected to continue in the years ahead because of technological, economical and ecological advantages of the materials. One of the latest additions to the ash family is palm oil fuel ash, a waste material obtained on burning of palm oil husk and palm kernel shell as fuel in palm oil mill boilers, which has been identified as a good pozzolanic material. This paper highlights test results on the performance behavior of palm oil fuel ash (POFA) in reducing the heat of hydration of concrete. Two concrete mixes namely OPC concrete i.e. concrete with 100% OPC as control, and POFA concrete i.e. concrete with 30% POFA and 70% OPC were prepared, and the temperature rise due to heat of hydration in both the mixes was recorded. It has been found that palm oil fuel ash not only reduced the total temperature rise but also delayed the time at which the peak temperature occurred. The results obtained and the observation made clearly demonstrate that the partial replacement of cement by palm oil fuel ash is advantageous, particularly for mass concrete where thermal cracking due to excessive heat rise is of great concern

Individual differences in embodied distance estimation in virtual reality

There are important individual differences when experiencing VR setups. We ran a study with 20 participants who got a scale-matched avatar and were asked to blind-walk to a VR target placed 2.5 meters away. In such setups, people typically underestimate distances by approximately 10% when virtual environments are viewed through head mounted displays. Consistent with previous studies we found that the underestimation was significantly reduced the more embodied the participants were. However, not all participants developed the same level of embodiment when exposed to the exact same conditions

Multiple sclerosis epidemiology in Middle East and North Africa: A systematic review and meta-analysis

Background: Multiple sclerosis (MS) is one of the most common neurological disorders and a leading cause of nontraumatic disability in young adults in many countries. Recent reports from the Middle East and North Africa have suggested a moderate to high risk of MS in these countries. Methods: A literature search was performed in August 2014 in MEDLINE, EMBASE, and IMEMR to retrieve original population-based studies on MS epidemiology in the Middle East and North African countries published between 1st January 1985 and 1st August 2014. We designed search strategies using the key words: MS, prevalence, incidence, and epidemiology. According to the inclusion criteria, 52 studies were included in this systematic review. Results: McDonald's criteria were the most widely used diagnostic criteria in the studies. Most studies were conducted in single hospitalbased centers with a defined catchment area. The female/male ratio ranged from 0.8 in Oman to 4.3 in Saudi Arabia. MS prevalence ranged from 14.77/100,000 population in Kuwait (2000) to 101.4/100,000 in Turkey (2006). The overall MS prevalence in the region was 51.52/100,000. The mean age at disease onset ranged from 25.2 years in Kuwait to 32.5 years in Northeastern Iran, with an overall estimate of 28.54 years. Conclusions: Recent advances in MS registries will allow nation-wide studies and temporal comparisons between countries, provided that age- and sex-standardized estimates are available. © 2015 S. Karger AG, Basel

I'm a Giant: Walking in Large Virtual Environments at High Speed Gains

Advances in tracking technology and wireless headsets enable walking as a means of locomotion in Virtual Reality. When exploring virtual environments larger than room-scale, it is often desirable to increase users' perceived walking speed, for which we investigate three methods. (1) Ground-Level Scaling increases users' avatar size, allowing them to walk farther. (2) Eye-Level Scaling enables users to walk through a World in Miniature, while maintaining a street-level view. (3) Seven-League Boots amplifies users' movements along their walking path. We conduct a study comparing these methods and find that users feel most embodied using Ground-Level Scaling and consequently increase their stride length. Using Seven-League Boots, unlike the other two methods, diminishes positional accuracy at high gains, and users modify their walking behavior to compensate for the lack of control. We conclude with a discussion on each technique's strength and weaknesses and the types of situation they might be appropriate for

The Association of Oral Bisphosphonate Use With Mortality Risk Following a Major Osteoporotic Fracture in the United Kingdom:Population-Based Cohort Study

OBJECTIVES: Bisphosphonates (BPs) might have extra benefits in reducing mortality because of their anti-atherosclerotic effects, but studies reported conflicting results. We investigated the association between oral BP use and mortality risk following a major osteoporotic fracture (MOF) in the United Kingdom. DESIGN: This was a population-based cohort study. SETTING AND PARTICIPANTS: In total, 163,273 adults aged 50 years and older with an MOF between 2000 and 2018 from the Clinical Practice Research Datalink in the United Kingdom. METHODS: Cox proportional hazards models were used to estimate the risk of all-cause mortality in current (0‒6 months), recent (7‒12 months), and past (>1 year) exposures to oral BPs after nonhip MOF and hip fracture. In addition, stratification by sex, BP type, and duration of follow-up was performed. RESULTS: Compared with never users of oral BPs, current BP use was associated with a 7% higher all-cause mortality risk after nonhip MOF, whereas a 28% lower all-cause mortality risk was observed after hip fracture. Past BP exposure was associated with a 14% and 42% lower risk after nonhip MOF and hip fracture, respectively. When considering only the first 5 years of follow-up, mortality risk associated with current BP use was significantly lower for both fracture groups, and the greatest reduction in mortality risk was observed within the first year. Women had slightly lower risk compared with men. CONCLUSIONS AND IMPLICATIONS: We found a slight increased risk of all-cause mortality with current BP exposure after a nonhip MOF; however, a protective effect was observed following a hip fracture. Both the timing and the effect size of an association based on the anti-atherosclerotic hypothesis of BPs are not supported by our results. The decreasing trend of the mortality risk with shorter durations of follow-up suggests that the observed association is likely due to unknown distortion or unknown pleiotropic properties of BPs

Оценка насыщения кислородом как показателя для интубации трахеи у пациентов с COVID-19: проспективное когортное исследование

   Background. Since the beginning of COVID-19 pandemic, the importance of clinical criteria for tracheal intubation in critically ill patients with respiratory failure became more noteworthy, especially in resource limitations. The objective was to evaluate the importance of hemoglobin oxygen saturation as a criterion for tracheal intubation in patients with COVID-19.   Materials and methods. This is a multi-center, prospective, observational cohort study. We included 117 patients with COVID-19 who needed respiratory support between March to June 2021. Patients were intubated by the protocol of each institution participating in the study and the anesthesiologist’s clinical judgement. Signs of respiratory failure, methods of respiratory support and patient outcome were recorded.   Results. Among 117 studied cases, 100 patients had hemoglobin oxygen saturation of 60–90 % in whom 58 were intubated. During hospitalization, 56 intubated patients and 14 non-intubated patients died (96.6 % Vs. 33.3 %).   Conclusion. Arterial blood hemoglobin oxygen saturation of 60–90 could not be the correct key to unlock the problem of intubation decision in patients with COVID-19. Therefore, hemoglobin oxygen saturation should not be solely regarded as an indication for intubation in COVID-19.    Введение. С началом пандемии COVID-19 возросла значимость клинических критериев для интубации трахеи у тяжелобольных пациентов с дыхательной недостаточностью, особенно в условиях ограниченных ресурсов.   Цель – оценить важность показателя насыщения гемоглобина кислородом как критерия для интубации трахеи у пациентов с COVID-19.   Материалы и методы. Многоцентровое проспективное обсервационное когортное исследование, включившее 117 пациентов с COVID-19, которые нуждались в респираторной поддержке в период с марта по июнь 2021 г. Пациенты были интубированы в соответствии с протоколом каждого участвовавшего в исследовании учреждения и клиническим заключением анестезиолога. Регистрировали признаки дыхательной недостаточности, методы респираторной поддержки и результаты лечения пациентов.   Результаты. Из 117 случаев у 100 пациентов насыщение гемоглобина кислородом составило 60–90 %, 58 из них были интубированы. Во время госпитализации 56 интубированных пациентов и 14 неинтубированных пациентов умерли (96,6 % против 33,3 %).   Заключение. Насыщение гемоглобина артериальной крови кислородом в пределах 60–90 % не может быть ключом к решению проблемы интубации у пациентов с COVID-19 и, следовательно, само по себе не может быть подходящим критерием для принятия решения об интубации