Investigation of relative humidity and induced-vortex effects on aircraft icing

Aircraft icing is an area of research that has drawn attention since the early times of powered flight at high altitudes. Since World War II, aircraft icing research has gained a great deal of momentum, and several branches of research have developed as a result. These branches include the experimental, analytical and computational methods. With the advent of high-speed computers, the computational methods are becoming the leading icing research area due to their low cost requirements. However, a significant hindrance is the lack of a complete understanding of the icing phenomena, which leads to discrepancies between the predictions and the experiments. In recent years, there have been efforts to improve this situation by accounting for several mechanisms within the computational models. These mechanisms include the droplet splash and re-impingement, water film dynamics, and different heat transfer mechanisms. In support of enhancing the understanding of the aircraft icing process, this Ph.D. study focuses on the relative humidity effects and the interaction of the induced vortices with the droplets and the surface water.;Currently the relative humidity effects are neglected in the icing prediction codes with the assumption that it can at best be a second-order effect. This Ph.D. study looks at the conditions in which the relative humidity effects can pose significant impact on the accreted ice shape. It was seen that the flow around the airfoil suction surfaces and the vortices, which have low-pressure cores, shed from the existing ice shape are highly supersaturated. Therefore, the suction surfaces and the aft regions of the main ice shape are exposed to condensation/deposition due to relative humidity effects. The time scales involved in the relative humidity effects were also investigated by using a numerical droplet growth experiment. In the particular case considered in this study, the required time to re-establish equilibrium, i.e. recover saturation conditions, varied from 12 milliseconds for droplets with 1 micron diameter to 5 seconds for droplets with 20 micron diameter. In an actual flight scenario, the direct impingement region mostly overlaps with the stagnation region, where the local flow is subsaturated. (Abstract shortened by UMI.)

A comparison of attitudes towards stuttering of non-stuttering preschoolers in the United States and Turkey

Background and objectives: Extensive research documents ubiquitous negative attitudes towards stuttering, but when and how they develop is unclear. This non-experimental, comparative study examined US and Turkish preschoolers to explore the origin of stuttering attitudes cross-culturally. Method: The authors compared stuttering attitudes of 28 US and 31 Turkish non-stuttering preschoolers on English and Turkish versions of experimental prototypes of the newly developed Public Opinion Survey on Human Attributes–Stuttering/Child (POSHA–S/Child). Children first watched a short video of two stuttering avatar characters and then answered oral questions about stuttering. Parents completed a demographic questionnaire. Differences in the US and Turkish POSHA–S/Child means were calculated using the Mann–Whitney U test. Results: Attitudes of the US and Turkish children were remarkably similar. Children rated most of the items negatively but also rated some items as neutral or positive. They held relatively more negative attitudes towards traits and personalities of children who stutter yet relatively more positive attitudes towards stuttering children’s potential. Conclusion: Stuttering attitudes in children appear to be partly independent of culture

Global Perspectives on Task Shifting and Task Sharing in Neurosurgery.

BACKGROUND: Neurosurgical task shifting and task sharing (TS/S), delegating clinical care to non-neurosurgeons, is ongoing in many hospital systems in which neurosurgeons are scarce. Although TS/S can increase access to treatment, it remains highly controversial. This survey investigated perceptions of neurosurgical TS/S to elucidate whether it is a permissible temporary solution to the global workforce deficit. METHODS: The survey was distributed to a convenience sample of individuals providing neurosurgical care. A digital survey link was distributed through electronic mailing lists of continental neurosurgical societies and various collectives, conference announcements, and social media platforms (July 2018-January 2019). Data were analyzed by descriptive statistics and univariate regression of Likert Scale scores. RESULTS: Survey respondents represented 105 of 194 World Health Organization member countries (54.1%; 391 respondents, 162 from high-income countries and 229 from low- and middle-income countries [LMICs]). The most agreed on statement was that task sharing is preferred to task shifting. There was broad consensus that both task shifting and task sharing should require competency-based evaluation, standardized training endorsed by governing organizations, and maintenance of certification. When perspectives were stratified by income class, LMICs were significantly more likely to agree that task shifting is professionally disruptive to traditional training, task sharing should be a priority where human resources are scarce, and to call for additional TS/S regulation, such as certification and formal consultation with a neurosurgeon (in person or electronic/telemedicine). CONCLUSIONS: Both LMIC and high-income countries agreed that task sharing should be prioritized over task shifting and that additional recommendations and regulations could enhance care. These data invite future discussions on policy and training programs

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Impacts of the fish farms on the water column nutrient concentrations and accumulation of heavy metals in the sediments in the eastern Aegean Sea (Turkey)

PubMed ID: 19242809We investigated potential effects of the fish farms on water column and sediment around Salih Island in the Gulluk Bay (Aegean Sea, Turkey) where four seasonal samplings were performed from October 2001 to August 2002. One measured physicochemical variables in water column including dissolved oxygen, nutrients (nitrite, nitrate, ammonium, phosphate and silicate), particulate organic carbon (POC) and chlorophyll a. Organic matter, total organic carbon (TOC) and heavy metals (Zn, Cu and Fe) were measured in sediment samples. Although occasional increases in ammonium and chlorophyll a concentrations were observed at the cage stations as compared to the control one, no statistically significant differences were detected among the stations in terms of nutrients, chlorophyll a and POC. On the other hand, significant differences were found in organic matter, TOC and heavy metals (Zn and Fe) of the sediments among the sampling stations. Despite these differences, our results indicate that concentrations of physicochemical variables and heavy metals were within the range of tolerable levels for the marine ecosystem, and the oligotrophic nature of the water column in the study area was able to assimilate organic and inorganic loads caused by the fish farms. © 2009 Springer Science+Business Media B.V.Acknowledgements Financial support for this work was provided by the Bodrum Aquaculture Research Institute, Turkish Ministry of Agriculture. -

A comparison of attitudes towards stuttering of non-stuttering preschoolers in the United States and Turkey

WOS: 000401198900001PubMed ID: 28470081Background and objectives: Extensive research documents ubiquitous negative attitudes towards stuttering, but when and how they develop is unclear. This non-experimental, comparative study examined US and Turkish preschoolers to explore the origin of stuttering attitudes cross-culturally. Method: The authors compared stuttering attitudes of 28 US and 31 Turkish non-stuttering preschoolers on English and Turkish versions of experimental prototypes of the newly developed Public Opinion Survey on Human Attributes-Stuttering/Child (POSHA-S/Child). Children first watched a short video of two stuttering avatar characters and then answered oral questions about stuttering. Parents completed a demographic questionnaire. Differences in the US and Turkish POSHA-S/Child means were calculated using the Mann-Whitney U test. Results: Attitudes of the US and Turkish children were remarkably similar. Children rated most of the items negatively but also rated some items as neutral or positive. They held relatively more negative attitudes towards traits and personalities of children who stutter yet relatively more positive attitudes towards stuttering children's potential. Conclusion: Stuttering attitudes in children appear to be partly independent of culture

Optimization of the snowflake divertor for power and particle exhaust on NSTX–U

In this paper, simple analytical modeling and numerical simulations performed with the multi-fluid edge transport code UEDGE are used to identify optimal snowflake divertor (SFD) configurations for heat flux mitigation and sufficient cryopumping performance on the National Spherical Torus eXperiment Upgrade (NSTX–U). A model is presented that describes the partitioning of sheath-limited SOL power and particle exhaust in the SFD as a result of diffusive transport to multiple activated strike points. The model is validated against UEDGE predictions and used to analyze a database of 70 SFD-minus equilibria. The optimal location for the entrance to a divertor cryopumping system on NSTX–U is computed for enabling sufficient pumping performance with acceptable power loading in a variety of SFD-minus configurations. UEDGE simulations of one promising equilibrium from the database indicate that a significant redistribution of power to the divertor legs occurs as a result of neutral particle removal near one of the SFD-minus strike points in the outboard scrape-off layer. It is concluded that pump placement at the optimal location is advantageous as the large number of compatible equilibria reduces the precision required of real-time SFD configuration control systems and enables acceptable divertor solutions even if UEDGE-predicted power redistribution slightly reduces the achievable pumping performance

A decision making tool considering risk assessment of sub-contracting agents for an air cargo shipment planning problem

Development of an efficient shipment plan for air cargo forwarders is a critical to obtaining considerable integration and consolidation savings and to meeting competitive requirements such as target costs. In this paper, we propose a decision making tool to solve a deterministic air cargo shipment planning problem with risk assessment of sub-contracting agents evaluating possible consolidations and integrations. The decision making tool consists of a risk assessment module based on historical data and a shipment planning module that includes a genetic algorithm (GA). Various benchmark instances are generated based on real life data obtained from a worldwide air cargo company to investigate the performance of the proposed methodology. In conclusion, the proposed methodology provide effective solutions in terms of solution quality and computational time. © 2018 Elsevier Ltd