bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient Thermo-Diffuso-Capillary Convection Around a Bubble in a Surfactant Solution: A Numerical Investigation Using the Volume-of-Fluid Technique
Authors: Kalaikadal D. S. , Manglik R. M. , Jog M. A. 
Published: December 2019

Abstract
Marangoni Convection occurs when a surface tension gradient is established at a liquid-gas interface. The variation in surface tension could be driven by an interface temperature gradient, resulting in Thermocapillary Convection, or by an interface concentration gradient, giving rise to Diffuso-Capillary Convection, or a combination of both. Such flows are found to be of interest in microgravity (and otherwise), as they are known to significantly contribute to heat and mass transfer enhancement at the interface. This paper deals with the computational study of bubble induced thermo-diffuso capillary convection in the presence of surfactants and a stratified thermal field.
Bubble induced thermo-capillary convection in a pure liquid has been substantially studied and the effects of various parameters like liquid properties, wettability, bubble size, channel depth, and temperature gradients on the strength of thermo-capillary currents and the associated heat transfer enhancement at the bubble interface are well established.
In this study the physico-chemical properties of an aqueous solution of Sodium-Dodecyl-Sulphate (SDS), a surfactant, were used to introduce the effects of surfactant concentration-induced surface-tension gradients in addition to the temperature induced gradients. Unlike in purely thermo-capillary flows, where the interface sees a near-constant surface-tension gradient from base to apex, the presence of surfactant molecules at the interface results in gradients that vary significantly along the interface with maximum gradients at the bubble base and the apex, resulting in a pair opposing vortices anchored to the bubble interface. The presence of the opposing vortices, results in weaker capillary-flows at higher thermal Marangoni numbers. This is in contrast with purely thermal Marangoni convection, where a larger Marangoni number yields a stronger capillary flow.
It was also observed that while the Marangoni number may provide an accurate estimation of heat-transfer enhancement under steady-state conditions, it may not be possible in the case of a transiently developing Marangoni-flow. The heat transfer enhancement is maximum near the time of bubble introduction and then diminishes to a lower, stable value. Also, the capillary flows and the associated heat transfer is found to significantly vary with the wetting behavior at the liquid-solid-vapor interface, even for the same set of Marangoni numbers.
Transient Subcooled Flow Boiling Phenomena in a Vertical Small Tube
Authors: Nakamura Yuji , Liu Qiusheng , Shibahara Makoto , Hata Koichi , Fukuda Katsuya 
Published: December 2019

Abstract
In this research, the transient heat transfer due to exponentially increasing heat input was experimentally measured for upward water flowing in a vertical small tube. The heat generation rate was increased exponentially with a function of Qoexp (t/τ), where, Qo is an initial heat generation rate, t represents time and τ is e-folding time. The heat generation rate was controlled by high speed computer system. The test tube was heated with exponentially increasing heat input by direct current. The average temperature of test tube was measured by resistance thermometry using a double bridge circuit. The experimental apparatus consists of a test section, a cooler, a heater, a pump, a tank and a pressurizer. The working fluid was distilled and deionized water. The inlet fluid temperature of test tube was controlled by the cooler and the heater. The system pressure was up to 800 kPa. The test tube was 0.7 mm in inner diameter and 12.0 mm in heated length respectively. The ratio of heated length to inner diameter was 17.1. The test tube was electrically isolated from experimental loop by Bakelite plates. The experimental data were compared with previous correlations of nucleate boiling. It was obtained that the experimented data agree well with full-developed flow boiling correlation by Rohsenow. Moreover, the transient critical heat flux (CHF) and nucleate boiling with onset of nucleate boiling (ONB) values increased with the increase in flow velocity. The transient CHFs and ONBs increased with a decrease in e-folding time at τ &lt; 1 s, and they approached steady-state value at τ &gt; 1 s. It was understood that the heat transfer is in steady-state at τ &gt; 1 s, and it is in transient state at τ &lt; 1 s.
On the Stefan Problem With Internal Heat Generation and Prescribed Heat Flux Conditions at the Boundary
Authors: Barannyk Lyudmyla , Williams Sidney D. V. , Ogidan Olufolahan Irene , Crepeau John C. , Sakhnov Alexey 
Published: December 2019

Abstract
We study the evolution of the solid-liquid interface during melting and solidification of a material with constant internal heat generation and prescribed heat flux at the boundary for a plane wall and a cylinder. The equations are solved by splitting them into transient and steady-state components and then using separation of variables. This results in an ordinary differential equation for the interface that involves infinite series. The initial value problem is solved numerically, and solutions are compared to the previously published quasi-static solutions. We show that when the internal heat generation and the heat flux at the boundary are close in value to each other, the motion of the phase change front takes longer to reach steady-state than when the values are farther apart. As the difference between the internal heat generation and the heat flux increases, the transient solutions become more dominant and the numerical solution of the phase change front does not reach steady-state before the outer boundary or centerline is reached. The difference between the internal heat generation and the heat flux at the boundary can be used to control the motion and speed of the interface. The problem has applications for a nuclear fuel rod during meltdown.
A Hybrid Absorption System With Generator Level Optical Control and Variable Flow Rate
Authors: Souza Gleidson , Vargas José V. C. , Balmant Wellington , Campos Marcos C. , Martinez Leonardo C. , Ordóñez Juan C. , Mariano André B. 
Published: December 2019

Abstract
Current refrigeration and air conditioning systems are mostly based on the vapor compression cycle, which require electrical energy input. Absorption systems have gained new interest due to the possibility of utilizing waste heat as energy input. In addition, the environmental impact generated by such systems is recognized as much smaller than vapor compression systems. Therefore, this work developed and characterized an absorption refrigeration system with an innovative generator level optical control and variable working fluid mass flow rate, with potential for use in industrial, commercial and residential heating, ventilation, air conditioning, and refrigeration (HVAC & R) systems. The system is hybrid, since it was designed to be fed with heat from the burning of different fuels and/or waste heat sources in complementary fashion. The system consists of: a condenser, an evaporator, two expansion valves, two absorbers, a centrifugal pump, a regenerative heat exchanger, a generator, a rectifier, a generator level optical control system, and two liquid accumulators. The developed level control system consists of 3 light Dependent Resistors (LDR) positioned inside a box built around a transparent level meter, and illuminated internally by a low power light bulb. A frequency inverter and a centrifugal pump allow for the working fluid solution inside the generator to be within a safe range for efficient cooling cycle operation. The system measured refrigeration capacity rate was 2.3 TR, which qualifies as a good performance, since the equipment was originally designed for 1 TR.
Thermal Mixing Downstream of a 90-Degree T-Junction: Laminar and Turbulent Flows
Authors: Farouk Bakhtier 
Published: December 2019

Abstract
A three-dimensional time dependent computational fluid dynamic (CFD) study of laminar and turbulent thermal mixing of two flows entering a 90° T-junction pipe is presented. The two incoming flows (both liquids) in the T-junction enter the flow domain with different inlet velocities, and temperatures. Water flow is considered in both the horizontal pipe and the vertical pipe. Inlet temperature differences and temperature dependent thermophysical properties are considered. Large eddy simulations (LES) with sub-grid scale (SGS) modeling were considered for the simulation of the turbulent cases. The flow characteristics, and thermal mixing behaviors and detailed mixing structures were simulated, and they showed that thermal mixing of the two streams are closely affected by the inlet conditions of the two streams and the inlet thermophysical properties of the two streams.
Diurnal Profiles of Physical Activity and Postures Derived From Wrist-Worn Accelerometry in UK Adults
Authors: Perez-Pozuelo Ignacio , White Thomas , Westgate Kate , Wijndaele Katrien , Wareham Nicholas J. , Brage Soren 
Published: December 2019

Background: Wrist-worn accelerometry is the commonest objective method for measuring physical activity in large-scale epidemiological studies. Research-grade devices capture raw triaxial acceleration which, in addition to quantifying movement, facilitates assessment of orientation relative to gravity. No population-based study has yet described the interrelationship and variation of these features by time and personal characteristics. Methods: 2,043 United Kingdom adults (35–65 years) wore an accelerometer on the non-dominant wrist and a chest-mounted combined heart-rate-and-movement sensor for 7 days free-living. From raw (60 Hz) wrist acceleration, we derived movement (non-gravity acceleration) and pitch and roll (forearm) angles relative to gravity. We inferred physical activity energy expenditure (PAEE) from combined sensing and sedentary time from approximate horizontal arm angle coupled with low movement. Results: Movement differences by time-of-day and day-of-week were associated with forearm angles; more movement in downward forearm positions. Mean (SD) movement was similar between sexes ∼31 (42) mg, despite higher PAEE in men. Women spent longer with the forearm pitched >0°, above horizontal (53% vs 36%), and less time at <0° (37% vs 53%). Diurnal pitch was 2.5–5° above and 0–7.5°below horizontal during night and daytime, respectively; corresponding roll angles were ∼0° (hand flat) and ∼20° (thumb-up). Differences were more pronounced in younger participants. All diurnal profiles indicated later wake-times on weekends. Daytime pitch was closer to horizontal on weekdays; roll was similar. Sedentary time was higher (17 vs 15 hours/day) in obese vs normal-weight individuals. Conclusions: More movement occurred in forearm positions below horizontal, commensurate with activities including walking. Findings suggest time-specific population differences in behaviors by age, sex, and BMI.
Association between age-related macular degeneration and subjective cognitive complaints
Authors: Zhu Zhuoting , Liao Huan , Wang Wei , Scheetz Jane , Zhang Jian , He Mingguang 
Published: December 2019

Purpose
To investigate the association between age-related macular degeneration (AMD) and subjective cognitive complaints (SCCs) in the USA.

Methods
A total of 5604 participants aged 40 years and older from the 2005–2008 National Health and Nutrition Examination Survey were included. Retinal photography was graded into no AMD, early and late AMD based on the modification of the Wisconsin Age-Related Maculopathy Grading System. SCCs were based on the self-reported difficulty in remembering or confusion. Sample weights were used to generate nationally representative data. Multivariate regression analyses were used to assess the association between AMD severity and SCCs, controlling for potential confounders.

Results
Participants with any AMD had higher prevalence of SCCs relative to participants without AMD (6.8% vs 13.6%, p<0.001). After adjusting for potential confounding factors, presence of any AMD was significantly associated with 1.62-fold higher odds of having SCCs (95% CI 1.16 to 2.27, p=0.007). Similarly, participants with early (OR 1.58; 95% CI 1.14 to 2.17, p=0.007) and late AMD (OR 2.02; 95% CI 1.08 to 3.79, p=0.030) were also associated with elevated odds of reporting SCCs after controlling for confounders.

Conclusions
We found significant associations between AMD severity and SCCs in this US population. More attention should be paid on the subjective memory function and potential risk of cognitive decline among patients with AMD.
Has Gavi lived up to its promise? Quasi-experimental evidence on country immunisation rates and child mortality
Authors: Jaupart Pascal , Dipple Lizzie , Dercon Stefan 
Published: December 2019

IntroductionGavi, the Vaccine Alliance, was set up in 2000 to improve access to vaccines for children living in the poorest countries. Funding has increased significantly over time, with Gavi disbursements reaching US $1.58 billion in 2015. We assess whether Gavi’s funding programmes have indeed increased immunisation coverage in 51 recipient countries for two key vaccines for 12–23 month olds: combined diphtheria, pertussis and tetanus (DPT) and measles. Additionally, we look at effects on infant and child mortality.MethodsTaking a difference-in-differences quasi-experimental approach to observational data, we estimate the impact of Gavi eligibility on immunisation coverage and mortality rates over time, using WHO/UNICEF figures covering 1995–2016. We control for economy size and population of each country as well as running a suite of robustness checks and sensitivity tests.ResultsWe find large and significant positive effects from Gavi’s funding programmes: on average a 12.02 percentage point increase in DPT immunisation coverage (95% CI 6.56 to 17.49) and an 8.81 percentage point increase in measles immunisation coverage (95% CI 3.58 to 14.04) over the period to 2016. Our estimates show Gavi support also induced 6.22 fewer infant deaths (95% CI −10.47 to −1.97) and 12.23 fewer under-five deaths (95% CI −19.66 to −4.79) per 1000 live births.ConclusionOur findings provide evidence that Gavi has had a substantial impact on the fight against communicable diseases for improved population and child health in lower-income countries. In this case, the health policy to verticalise aid—specifically development assistance for health—via a specialised global fund has had positive outcomes.
Protocol for a scoping review on information needs and information-seeking behaviour of people with dementia and their non-professional caregivers
Authors: Au Shu Ting , Soong Aijia , Kyaw Bhone Myint , Tudor Car Lorainne 
Published: December 2019

BackgroundDementia is a debilitating disease that can lead to major changes in a patient’s behaviour and function. It is important to educate both patients with dementia and their non-professional caregivers about the disease. Yet, currently available sources do not seem to be effective for patients and caregivers, who report a need for more information and guidance. A systematic identification of the patients’ and caregivers’ needs for information and information-seeking behaviour is needed to create information resources that are relevant and beneficial to the target population.ObjectivesThis is a protocol for a scoping review aimed at gathering knowledge on the information needs and information-seeking behaviour of patients with dementia and their non-professional caregivers. Our aim was also to provide recommendations for development of future dementia information resources.MethodsThe study will commence in November 2018. Both quantitative and qualitative studies on the information needs of patients with dementia or caregivers will be examined using Arksey and O’Malley’s methodological framework for scoping studies. A comprehensive literature search will be conducted in electronic databases and grey literature sources. We will also screen reference lists of included studies and related systematic reviews for additional eligible studies. Two authors will perform screening of citations for eligibility and independently extract data from the included studies in parallel. Any discrepancies will be resolved through discussion. The findings will be presented through a narrative synthesis and reported in line with PreferredReporting Items for Systematic Reviews and Meta-Analyses reporting guidelines.Ethics and disseminationIn this review, all included data will originate from published literature. Ethics approval is therefore not a requirement. We will present our findings at relevant conferences and will submit them for publication in peer-reviewed journals.
Vitamin D prescribing in children in UK primary care practices: a population-based cohort study
Authors: Wan Mandy , Horsfall Laura J , Basatemur Emre , Patel Jignesh Prakash , Shroff Rukshana , Rait Greta 
Published: December 2019

ObjectiveTo examine temporal changes in the incidence and patterns of vitamin D supplementation prescribing by general practitioners (GPs) between 2008 and 2016.DesignPopulation-based cohort study.SettingUK general practice health records from The Health Improvement Network.ParticipantsChildren aged 0 to 17 years who were registered with their general practices for at least 3 months.Outcome measuresAnnual incidence rates of vitamin D prescriptions were calculated, and rate ratios were estimated using multivariable Poisson regression to explore differences by sociodemographic factors. Data on the type of supplementation, dose, dosing schedule, linked 25-hydroxyvitamin D (25(OH)D) laboratory test results and clinical symptoms suggestive of vitamin D deficiency were analysed.ResultsAmong 2 million children, the crude annual incidence of vitamin D prescribing increased by 26-fold between 2008 and 2016 rising from 10.8 (95% CI: 8.9 to 13.1) to 276.8 (95% CI: 264.3 to 289.9) per 100 000 person-years. Older children, non-white ethnicity and general practices in England (compared with Wales/Scotland/Northern Ireland) were independently associated with higher rates of prescribing. Analyses of incident prescriptions showed inconsistent supplementation regimens with an absence of pre-supplementation 25(OH)D concentrations in 28.7% to 56.4% of prescriptions annually. There was an increasing trend in prescribing at pharmacological doses irrespective of 25(OH)D concentrations, deviating in part from UK recommendations. Prescribing at pharmacological doses for children with deficient status increased from 3.8% to 79.4%, but the rise was also observed in children for whom guidelines recommended prevention doses (0% to 53%). Vitamin D supplementation at pharmacological doses was also prescribed in at least 40% of children with no pre-supplementation 25(OH)D concentrations annually.ConclusionsThere has been a marked and sustained increase in vitamin D supplementation prescribing in children in UK primary care. Our data suggests that national guidelines on vitamin D supplementation for children are not consistently followed by GPs.
Prevalence of bullying in the nursing workplace and determinant factors: a nationwide cross-sectional Polish study survey
Authors: Serafin Lena Izabela , Czarkowska-Pączek Bożena 
Published: December 2019

ObjectivesIn the present study, we aimed to investigate the prevalence of bullying among Polish nurses, and to identify the most common negative acts, as well as individual and work-related risk factors for workplace bullying.MethodsCross-sectional study designed using an online survey. The total study sample was 404 nurses, each having over 6 months of working experience. Data were collected using the Polish version of the Negative Act Questionnaire-Revised. Linear stepwise regression analysis and logistic regression analysis were performed to assess predictors of greater reporting of perceived workplace bullyingResultsBullying was experienced by 65.84% of participants. Perceived workplace bullying was associated with sex (p=0.043), age (p=0.003), seniority (p=0.006), number of working hours per week (p=0.010) and position (p=0.029). Logistic regression analysis with the dependent variable of bullying according to Leymann’s rigorous criteria revealed that the model could include four variables: age from 50 to 59, seniority of 11–15 years,>45 working hours per week and a bachelor’s degree in nursing.ConclusionsAn alarming percentage of nurses were victims of bullying. Among all variables included in the regression model, the most significant predictors of perceived workplace bullying were age, seniority, work overtime and bachelor’s degree education. Bullying prevention and improvement of well-being at work must be addressed as part of an overall strategy to deal with turnover.
Physician, heal thyself: a cross-sectional survey of doctors’ personal prescribing habits
Authors: Hartnett Yvonne , Drakeford Clive , Dunne Lisa , McLoughlin Declan M , Kennedy Noel 
Published: December 2019

BackgroundSelf-prescribing and prescribing to personal contacts is explicitly discouraged by General Medical Council guidelines.AimsThis study examines how widespread the practice of self-prescribing and prescribing to personal contacts is.MethodsA 16-item questionnaire was distributed via an online forum comprising 4445 young medical doctors (representing 20% of all Irish registered doctors), which asked respondents about previous prescribing to themselves, their families, friends and colleagues, including the class of medication prescribed. Demographic details were collected including medical grade and specialty.ResultsA total of 729 responses were obtained, the majority of which were from young non-consultant hospital doctors from a range of specialties. Two-thirds of respondents had self-prescribed, over 70% had prescribed to family, and nearly 60% had prescribed to a friend or colleague. Older doctors were more likely to self-prescribe (χ2=17.51, p<0.001). Interns being less likely to self-prescribe was not unexpected (χ2=69.55, p<0.001), while general practitioners (GPs) and paediatricians were more likely to self-prescribe (χ2=13.33, p<0.001;χ2=11.35, p<0.001). GPs, paediatricians and hospital medicine specialties were more likely to prescribe to family (χ2=5.19, p<0.05;χ2=8.38, p<0.05;χ2=6.17, p<0.05) and surgeons were more likely to prescribe to friends (χ2=15.87, p<0.001). Some 3% to 7% who had self-prescribed had prescribed an opiate, benzodiazepine or psychotropic medication. Male doctors, anaesthetists and surgeons were more likely to self-prescribe opioids (χ2=7.82, p<0.01;χ2=7.31, p<0.01;χ2=4.91, p<0.05), while those in hospital medicine were more likely to self-prescribe psychotropic medications (χ2=5.47, p<0.05).ConclusionPrescribing outside the traditional doctor-patient relationship is widespread despite clear professional guidance advising against it.