Numerical investigation of the energy performance of a guideless irregular heat and mass exchanger with corrugated heat transfer surface for dew point cooling

© 2016 The Author(s) The paper presents an investigation into the energy performance of a novel irregular heat and mass exchanger for dew point cooling which, compared to the existing flat-plate heat exchangers, removed the use of the channel supporting guides and implemented the corrugated heat transfer surface, thus expecting to achieve the reduced air flow resistance, increased heat transfer area, and improved energy efficiency (i.e. Coefficient of Performance (COP)) of the air cooling process. CFD simulation was carried out to determine the flow resistance (K) factors of various elements within the dry and wet channels of the exchanger, while the ‘finite-element’ based ‘Newton-iteration’ numerical simulation was undertaken to investigate its cooling capacity, cooling effectiveness and COP at various geometrical and operational conditions. Compared to the existing flat-plate heat and mass exchangers with the same geometrical dimensions and operational conditions, the new irregular exchanger could achieve 32.9%–37% higher cooling capacity, dew-point and wet-bulb effectiveness, 29.7%–33.3% higher COP, and 55.8%–56.2% lower pressure drop. While undertaking dew point air cooling, the irregular heat and mass exchanger had the optimum air velocity of 1 m/s within the flow channels and working-to-intake air ratio of 0.3, which allowed the highest cooling capacity and COP to be achieved. In terms of the exchanger dimensions, the optimum height of the channel was 5 mm while its length was in the range 1–2 m. Overall, the proposed irregular heat and mass exchanger could lead to significant enhanced energy performance compared to the existing flat-plate dew point cooling heat exchanger of the same geometrical dimensions. To achieve the same amount cooling output, the irregular heat and mass exchanger had the reduced size and cost against the flat-plate ones

Hybrid MBE-CBE Growth and Characterization of Al 0.48 In 0.52 As on InP(100) for avalanche photodiode applications Motivation

International audienceIn this work, we demonstrate the epitaxial growth of high quality, low strain and low background doping of Al0.48In0.52As at 500°C on Fe-doped semi-insulating InP(100) substrate by using hybrid MBE-CBE technique. The precursors that were used are: solid aluminum, solid indium, TriMethylIndium (TMIn) and thermally cracked arsine. Using Nomarski, we observed smooth surfaces for the as grown layers. High-Resolution X-ray Diffraction (HR-XRD) in the vicinity of the (004) reflexion shows a lattice mismatch in the range -137 to 127ppm. The carrier density of undoped layers, obtained by Hall measurement at room temperature, is as low as 3E+15 cm-3 which is three orders of magnitude lower than the identical layers grown by organometallics sources. Photoluminescence (PL) for Al0.48In0.52As at low temperature (LT) shows a good optical quality. The quality and purity of the alloys grown here are compatible with high performance APD for optical communication

Obstetric emergencies in the maternity ward of the Ignace Deen national hospital CHU of Conakry: sociodemographic, therapeutic and maternal fetal prognosis aspects

Background: Despite government efforts to reduce maternal mortality, the risk of a woman dying from obstetric complications is about one in six in the poorest regions of the world compared to one in thirty thousand in North Europe. The objective was therefore to describe the clinical socio-demographic aspects and to establish the maternal and fetal prognosis of obstetric emergencies.Methods: This was a descriptive cross-sectional prospective study over a 6-month period from January 1 to June 30, 2020 carried out at the maternity ward of the Ignace Deen national hospital (Conakry university hospital) in Guinea. The study looked at a continuous series of 662 obstetric emergency cases.Results: The frequency of admission of obstetric emergencies was 22.62%. They concerned young women (29.5 years old) on average, first-time mothers (53.32%), with low income professional activities, evacuated from a peripheral maternity unit (63.14%), no schooling (44.9%), married (92.3%), using the more often a means of public transport (66.5%) and whose pregnancies were poorly monitored (63.9%). Fetal emergencies were dominated by acute fetal distress (91.3%) and maternal emergencies were dominated by hypertensive emergencies (pre-eclampsia and eclampsia 37.44%) followed by hemorrhagic emergencies (last trimester hemorrhage and postpartum hemorrhage 34.34%). Pregnant and parturient women were more frequently admitted to labor (62.7%) and gave birth more frequently by caesarean section (86.70%). the staff reacted promptly to make a treatment decision in 75.5% of cases within fifteen minutes. emergency procedures were performed in less than fifteen minutes in almost all cases (97.4%), specific treatment was carried out in less than an hour in the majority of cases (68.3%). The maternal case fatality rate was 4.1% with the main cause of death being hemorrhagic shock of 51.8%. The stillbirth rate was 17.4%.Conclusions: The anticipation of emergency obstetric care (SOU) and close collaboration between the obstetrician, the anesthesiologist-resuscitator are essential in the management of obstetric emergencies

School physical activity intervention effect on adolescents' performance in mathematics

Purpose: The primary aim of this study was to test the effect of a school-based physical activity intervention on adolescents’ performance in mathematics. A secondary aim was to explore potential mechanisms that might explain the intervention effect. Methods: The Activity and Motivation in Physical EDucation intervention was evaluated using a two-arm cluster randomized controlled trial in 14 secondary schools located in low socioeconomic areas of Western Sydney, Australia. Study participants (n = 1173) were grade 8 students (mean age = 12.94 yr, SD = 0.54). The multicomponent intervention was designed to help teachers maximize students’ opportunities for moderate-to-vigorous physical activity (MVPA) during physical education (PE) and enhance students’ motivation toward PE. Mathematics performance was assessed as part of national testing in grade 7, which was the year before the trial began and then again in grade 9. Potential mediators were: (i) proportion of PE lesson time that students spent in MVPA and leisure time MVPA (%), measured using Actigraph GT3X+ accelerometers, and (ii) students’ self-reported engagement (behavioral, emotional, and cognitive) during mathematics lessons. Mediators were assessed at baseline (grade 8) and follow-up (grade 9, 14–15 months after baseline). Results: The effect of the intervention on mathematics performance was small-to-medium (β = 0.16, P < 0.001). An intervention effect was observed for MVPA% in PE (β = 0.59, P < 0.001), but not for leisure time MVPA or any of the engagement mediators. There were no significant associations between changes in potential mediators and mathematics performance. Conclusions: The Activity and Motivation in Physical EDucation intervention had a significant positive effect on mathematics performance in adolescents. However, findings should be interpreted with caution as the effect was small and not associated with changes in hypothesized mediators

Understanding Varied Attitudes Towards Muslims

The focus of this research was to determine the prevalence and type of Islamophobia in the Victorian population. Islamophobia sentiment feeds the actions of right-wing extremist attacks on Muslim communities. But it has also become widespread in Australian society, and normalised in everyday settings, such as our mainstream media. Islamophobia cannot be treated with a singular approach or mode of intervention. Our study comes at a critical time; it provides empirical evidence on the extent of the problem, as well as documenting the varied manifestations of Islamophobic sentiment, with the view to developing potential action points and policy. In November 2019 we undertook a survey of 4019 Victorians. We asked questions on their attitudes towards cultural diversity, racial equality and privilege; trust and fairness; Muslims and Islam; and other ethno-cultural groups in Australian society; their experiences of racism and discrimination; their contact with Muslims and knowledge of Islam; and their political affiliation. To our knowledge, this was the largest survey undertaken in Victoria with the purpose of solely measuring Victorians perceptions of Muslims and Islam. Based on respondents’ answers, we used latent class analysis to segment the Victorian population. Five groups were generated: Islamophobic, Islamophobic with assimilationist tendencies, Undecided, Progressive with concerns about Islam, and Progressive. We then distilled the demographic and attitudinal attributes of these groups, with the view to identifying roles and drivers to help guide policy and intervention. We tested this five group segmentation with community organisations in Victoria working in the broad areas of diversity and multiculturalism, and with a particular emphasis on Muslim and non-Muslim relations. The groupings made sense on-the-ground, and they provided a strong pathway forward for program and policy design

Fistula recurrence, pregnancy, and childbirth following successful closure of female genital fistula in Guinea : a longitudinal study

Background: Female genital fistula is a devastating maternal complication of delivery in developing countries. We sought to analyse the incidence and proportion of fistula recurrence, residual urinary incontinence, and pregnancy after successful fistula closure in Guinea, and describe the delivery-associated maternal and child health outcomes. Methods: We did a longitudinal study in women discharged with a closed fistula from three repair hospitals supported by Engender Health in Guinea. We recruited women retrospectively (via medical record review) and prospectively at hospital discharge. We used Kaplan-Meier methods to analyse the cumulative incidence, incidence proportion, and incidence ratio of fistula recurrence, associated outcomes, and pregnancy after successful fistula closure. The primary outcome was recurrence of fistula following discharge from repair hospital in all eligible women who consented to inclusion and could provide follow-up data. Findings: 481 women eligible for analysis were identified retrospectively (from Jan 1, 2012, to Dec 31, 2014; 348 women) or prospectively (Jan 1 to June 20, 2015; 133 women), and followed up until June 30, 2016. Median follow-up was 28.0 months (IQR 14.6-36.6). 73 recurrent fistulas occurred, corresponding to a cumulative incidence of 71 per 1000 person-years (95% CI 56.5-89.3) and an incidence proportion of 18.4% (14.8-22.8). In 447 women who were continent at hospital discharge, we recorded 24 cases of post-repair residual urinary incontinence, equivalent to a cumulative incidence of 23.1 per 1000 person-years (14.0-36.2), and corresponding to 10.3% (5.2-19.6). In 305 women at risk of pregnancy, the cumulative incidence of pregnancy was 106.0 per 1000 person-years, corresponding to 28.4% (22.8-35.0) of these women. Of 50 women who had delivered by the time of follow-up, only nine delivered by elective caesarean section. There were 12 stillbirths, seven delivery-related fistula recurrences, and one maternal death. Interpretation: Recurrence of female genital fistula and adverse pregnancy-related maternal and child health outcomes were frequent in women after fistula repair in Guinea. Interventions are needed to safeguard the health of women after fistula repair

Ring vaccination with rVSV-ZEBOV under expanded access in response to an outbreak of Ebola virus disease in Guinea, 2016: an operational and vaccine safety report.

BACKGROUND: In March, 2016, a flare-up of Ebola virus disease was reported in Guinea, and in response ring vaccination with the unlicensed rVSV-ZEBOV vaccine was introduced under expanded access, the first time that an Ebola vaccine has been used in an outbreak setting outside a clinical trial. Here we describe the safety of rVSV-ZEBOV candidate vaccine and operational feasibility of ring vaccination as a reactive strategy in a resource-limited rural setting. METHODS: Approval for expanded access and compassionate use was rapidly sought and obtained from relevant authorities. Vaccination teams and frozen vaccine were flown to the outbreak settings. Rings of contacts and contacts of contacts were defined and eligible individuals, who had given informed consent, were vaccinated and followed up for 21 days under good clinical practice conditions. FINDINGS: Between March 17 and April 21, 2016, 1510 individuals were vaccinated in four rings in Guinea, including 303 individuals aged between 6 years and 17 years and 307 front-line workers. It took 10 days to vaccinate the first participant following the confirmation of the first case of Ebola virus disease. No secondary cases of Ebola virus disease occurred among the vaccinees. Adverse events following vaccination were reported in 47 (17%) 6-17 year olds (all mild) and 412 (36%) adults (individuals older than 18 years; 98% were mild). Children reported fewer arthralgia events than adults (one [<1%] of 303 children vs 81 [7%] of 1207 adults). No severe vaccine-related adverse events were reported. INTERPRETATION: The results show that a ring vaccination strategy can be rapidly and safely implemented at scale in response to Ebola virus disease outbreaks in rural settings. FUNDING: WHO, Gavi, and the World Food Programme

Quantifying the value of viral genomics when inferring who infected whom in the 2014–16 Ebola virus outbreak in Guinea

Transmission trees can be established through detailed contact histories, statistical or phylogenetic inference, or a combination of methods. Each approach has its limitations, and the extent to which they succeed in revealing a 'true' transmission history remains unclear. In this study, we compared the transmission trees obtained through contact tracing investigations and various inference methods to identify the contribution and value of each approach. We studied eighty-six sequenced cases reported in Guinea between March and November 2015. Contact tracing investigations classified these cases into eight independent transmission chains. We inferred the transmission history from the genetic sequences of the cases (phylogenetic approach), their onset date (epidemiological approach), and a combination of both (combined approach). The inferred transmission trees were then compared to those from the contact tracing investigations. Inference methods using individual data sources (i.e. the phylogenetic analysis and the epidemiological approach) were insufficiently informative to accurately reconstruct the transmission trees and the direction of transmission. The combined approach was able to identify a reduced pool of infectors for each case and highlight likely connections among chains classified as independent by the contact tracing investigations. Overall, the transmissions identified by the contact tracing investigations agreed with the evolutionary history of the viral genomes, even though some cases appeared to be misclassified. Therefore, collecting genetic sequences during outbreak is key to supplement the information contained in contact tracing investigations. Although none of the methods we used could identify one unique infector per case, the combined approach highlighted the added value of mixing epidemiological and genetic information to reconstruct who infected whom