Probability techniques for reliability analysis of composite materials

Traditional design approaches for composite materials have employed deterministic criteria for failure analysis. New approaches are required to predict the reliability of composite structures since strengths and stresses may be random variables. This report will examine and compare methods used to evaluate the reliability of composite laminae. The two types of methods that will be evaluated are fast probability integration (FPI) methods and Monte Carlo methods. In these methods, reliability is formulated as the probability that an explicit function of random variables is less than a given constant. Using failure criteria developed for composite materials, a function of design variables can be generated which defines a 'failure surface' in probability space. A number of methods are available to evaluate the integration over the probability space bounded by this surface; this integration delivers the required reliability. The methods which will be evaluated are: the first order, second moment FPI methods; second order, second moment FPI methods; the simple Monte Carlo; and an advanced Monte Carlo technique which utilizes importance sampling. The methods are compared for accuracy, efficiency, and for the conservativism of the reliability estimation. The methodology involved in determining the sensitivity of the reliability estimate to the design variables (strength distributions) and importance factors is also presented

Can exhaled carbon monoxide be used as a marker of exposure? A cross-sectional study in young adults

Carbon monoxide (CO) poisoning is a major public health issue worldwide. People are exposed to CO in their daily lives, with one of the common sources of CO being cigarette smoking. Inhalation of CO leads to elevated carboxyhaemoglobin (COHb) levels in the blood and also in exhaled CO concentration. Several factors have been shown to affect COHb concentration and COHb half-life. However, factors affecting exhaled CO concentration and exhaled CO half-life are not well understood. The present study aimed to investigate the potential factors related to baseline exhaled CO concentration and exhaled CO half-life among smokers. A cross-sectional study was conducted between 26 January and 30 June 2019, and young adults were recruited into the study. A total of 74 participants (mean age: 27.1 years, 71.6% males and 28.4% females) attended the study. They were invited to complete a questionnaire, including demographic, physiological, and behavioural factors. Then, exhaled CO measurements were taken. These measurements were taken before and after smoking a single cigarette for smokers and only once for non-smokers. The average baseline exhaled CO concentration was 6.9 ± 4.9 ppm for smokers and 1.9 ± 0.5 ppm for non-smokers. The mean of exhaled CO half-life was around 273.3 min (4.6 h) for smokers. No difference was seen in exhaled CO half-life between light smokers and heavy smokers in the smoking group. Gender and cigarettes smoked weekly affected baseline exhaled CO in smokers. Even though height seemed to positively associate with exhaled CO half-life, the relationship disappeared when adjusting by gender and weight. Therefore, exhaled CO could be used as a marker of CO exposure, but we cannot ignore the factors mentioned in the study. For future study, considering factors related to smoking habits and smoking style are recommended as these may affect total inhaled CO

Effects of elevated carbon dioxide levels on response speed in cognitive test

To explore the associations of exposure to carbon dioxide with adults' response speed, 69 participants were invited to participate in the experiment conducted in an environmentally controlled chamber. Participants were exposed alone in three separate sessions, each lasting one hour, with a fixed ventilation rate, temperature and relative humidity level and the CO2 levels fixed at 600ppm, 1500ppm and 2100ppm, respectively. A validated neurobehavioral test battery, the Behavioural Assessment and Research System (BARS) was used to assess participants' cognitive performance, and response times were collected. Response speed was assessed in ten different tests. After adjusting for potential confounders (age, gender, and education), results showed no significant differences in eight out of the ten neurobehavioral tests. For the Selective Attention test, participants responded faster (lower response time) under CO2 levels of 2100ppm compared to 600ppm (adj.β-coef. -17.57, 95% CI (-29.45, -5.68), p-value=0.004). For the Progressive Ratio Test, participants' response times significantly decreased with CO2 levels increased. Results indicate no statistical link between CO2 levels and response speed, with only two out of ten comparisons being significant

Barriers to Optimal Health for Under 5s Experiencing Homelessness and Living In Temporary Accommodation in High-Income Countries: A Scoping Review

BACKGROUND: The first 5 years of life are crucial for optimising growth, health, and cognitive development. However, many children do not reach their full cognitive and developmental potential because of multilevel barriers, including those resulting from poverty and homelessness. This review summarises the evidence characterising the barriers to achieving optimal health and cognitive outcomes, and to accessing health services for homeless children younger than 5 years of age (U5s)-one of the most vulnerable populations in High Income Countries (HICs). METHODS: For this scoping review, we followed the PRISMA-ScR checklist and CATS framework. We searched Medline, PubMed, Embase, CINAHL, Web of Science, OVID Maternity and Infant Care, and The Cochrane Library (publications dates from Jan 1, 1980, to Jun 23, 2020) using the key words “homelessness”, “housing”, “paediatrics”, “interpersonal relations”, “social exclusion”, “toddler”, “children under 5”, “engagement”, and “communication and insecurity”. The search strategy yielded 3253 articles. Retrieved articles were organised by study design. Because of the considerable heterogeneity of methods and outcomes, we used a narrative synthesis analytic approach. Our outcome of interest was barriers to optimal health and accessing health services, focusing on U5s living in HICs. FINDINGS: Twenty-nine full texts were selected in the final synthesis, including primary research studies and systematic or narrative reviews of primary research studies from HICs. There was limited evidence describing links among housing insecurity, health, and cognitive outcomes in U5s. This age group was rarely studied as a discrete group and often combined with older ages (eg, ≤25 years). The quality of articles varied greatly because of the heterogeneity in study design. Nevertheless, important themes were identified: barriers were described at the individual and family level (eg, ethnicity, immigration status, and fear), system level (eg, policies, poor access to medication, absence of care plan, and no insurance) and community level (eg, transportation limitations and poor housing conditions). INTERPRETATION: Although evidence is sparse, further methodologically rigorous research is needed to identify what barriers exist for U5s and their parents in accessing health services, and how this affects the child’s health. The multi-level nature of these barriers implies a system’s approach may be required. However, more evidence is needed including cross-sector studies and tailored interventions to address these barriers by working directly with experts with experience of social exclusion and their children

School Flexible Learning Spaces, Student Movement Behavior and Educational Outcomes among Adolescents: A Mixed-Methods Systematic Review

BACKGROUND: To achieve sustainability, we must consider scalable improvements in student movement behavior in the classroom setting, educational priorities. Flexible learning spaces that employ student‐centered pedagogy and contain a range of furniture and layout options, implemented to improve educational outcomes, may enable unintended health benefits. In this review, we summarize the evidence on the effects of flexible learning spaces on adolescent student movement behaviors and educational outcomes. METHODS: We searched 5 databases, retrieving 5 quantitative and one qualitative article meeting the review criteria. RESULTS: Students in flexible learning spaces spent less time sitting, and more time standing and moving. Students were also more engaged, on‐task, and collaborated and interacted more. Academic results for English, Mathematics and Humanities for those in flexible learning spaces were higher than peers in traditional classrooms. CONCLUSION: Evidence from the reviewed studies suggests that there may be beneficial outcomes across some movement behaviors as well as learning outcomes in classrooms that employ student‐centered pedagogy and use a built environment that facilitates autonomy and choice around where and how to learn. These learning environments present an opportunity for an interdisciplinary approach to address sedentary behavior in classrooms

Indoor PM2.5 exposure in London's domestic stock: Modelling current and future exposures following energy efficient refurbishment

Simulations using CONTAM (a validated multi-zone indoor air quality (IAQ) model) are employed to predict indoor exposure to PM2.5 in London dwellings in both the present day housing stock and the same stock following energy efficient refurbishments to meet greenhouse gas emissions reduction targets for 2050. We modelled interventions that would contribute to the achievement of these targets by reducing the permeability of the dwellings to 3 m3 m−2 h−1 at 50 Pa, combined with the introduction of mechanical ventilation and heat recovery (MVHR) systems. It is assumed that the current mean outdoor PM2.5 concentration of 13 μg m−3 decreased to 9 μg m−3 by 2050 due to emission control policies. Our primary finding was that installation of (assumed perfectly functioning) MVHR systems with permeability reduction are associated with appreciable reductions in PM2.5 exposure in both smoking and non-smoking dwellings. Modelling of the future scenario for non-smoking dwellings show a reduction in annual average indoor exposure to PM2.5 of 18.8 μg m−3 (from 28.4 to 9.6 μg m−3) for a typical household member. Also of interest is that a larger reduction of 42.6 μg m−3 (from 60.5 to 17.9 μg m−3) was shown for members exposed primarily to cooking-related particle emissions in the kitchen (cooks). Reductions in envelope permeability without mechanical ventilation produced increases in indoor PM2.5 concentrations; 5.4 μg m−3 for typical household members and 9.8 μg m−3 for cooks. These estimates of changes in PM2.5 exposure are sensitive to assumptions about occupant behaviour, ventilation system usage and the distributions of input variables (±72% for non-smoking and ±107% in smoking residences). However, if realised, they would result in significant health benefits

Autophagy modulation in lymphocytes from COVID-19 patients. new therapeutic target in SARS-COV-2 infection

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the novel coronavirus, causing coronavirus disease 2019 (COVID-19). During virus infection, several pro-inflammatory cytokines are produced, leading to the “cytokine storm.” Among these, interleukin (IL)-6, tumor necrosis factor‐α (TNF‐α), and IL-1β seem to have a central role in the progression and exacerbation of the disease, leading to the recruitment of immune cells to infection sites. Autophagy is an evolutionarily conserved lysosomal degradation pathway involved in different aspects of lymphocytes functionality. The involvement of IL-6, TNF‐α, and IL-1β in autophagy modulation has recently been demonstrated. Moreover, preliminary studies showed that SARS-CoV-2 could infect lymphocytes, playing a role in the modulation of autophagy. Several anti-rheumatic drugs, now proposed for the treatment of COVID-19, could modulate autophagy in lymphocytes, highlighting the therapeutic potential of targeting autophagy in SARS-CoV-2 infection