bluuebunny/crossref_metadata_2025 huggingface dataset:
Consideration of Air Bubble Dynamics in 1D Hydraulic Pipeline Simulation – Source Term Development and Verification Utilizing Transmission Line Theory
Authors: Guse Fabian , Pasquini Enrico , Schmitz Katharina
Published: December 2021

In fluid power systems, the presence of undissolved air greatly influences the properties of the liquid-gas mixture. Even marginal amounts of undissolved air may drastically reduce the apparent bulk modulus of the mixture. In current state-of-the-art 1D simulation tools, the estimation of the apparent bulk modulus of the mixture is based on the assumption that both liquid and gas fractions act as springs. However, the so-called Rayleigh-Plesset equation frequently used for cavitation analysis shows that the gas bubbles should rather be regarded as non-linear mass-spring-damper systems, implicating a frequency-dependent stiffness of the gas phase. In the present paper, these dynamic effects are investigated by considering monodisperse as well as polydisperse mixtures. For the polydisperse case, a log-normal bubble size distribution is used. First, a frequency domain solution for the bubble dynamics is developed by linearizing the Rayleigh-Plesset equation. An expression of the mixture bulk modulus is derived, which is complex-valued and frequency-dependent. Based on the bulk modulus, a theoretical solution for the dynamics of a whole pipeline is developed by utilizing transmission line theory. It is shown that the dynamics of the bubbles leads to a significant shift of the system’s natural frequencies towards lower values — a phenomenon that needs to be accounted for during the design phase of a fluid power system. After the development of this analytical solution, by introducing a bubble dynamics source term, an established numerical scheme for 1D pipe simulation based on the method of characteristics is expanded. Finally, the newly developed numerical approach is compared with the analytical solution in order to determine its accuracy. The findings and simulation approaches in this work will enable fluid power system engineers to predict dynamic system behavior more precisely during early stages of system layout.
Measurement of Step Responses of Flowrate in a Pipe Using a Kalman-Filtering Laminar Flowmeter
Authors: Sanada Kazushi
Published: December 2021

The aim of our research project is to develop a Kalman filter system which estimates unsteady flowrate of a pipe using a laminar flowmeter. In this study, incompressible flow is assumed as working fluid. When the flow becomes turbulent, it is difficult to establish flow model for turbulent friction. In this study, a laminar flowmeter is constructed in which thirty-two narrow pipes of 1mm in inner diameter are bundled and inserted in main flow path. When fluid flow in the narrow pipe is laminar flow, the Kalman filter theory can be applied to the flow of the narrow pipe. Kalman filter is applied to one of narrow pipes of laminar flowmeter. Both upstream and downstream pressure signals of the targeted narrow pipe are input to the Kalman filter. Midpoint pressure measured by a pressure sensor is compared with midpoint pressure signal which is estimated by the Kalman filter. When flow is laminar flow or the system has linear characteristics, an error signal between estimated pressure and measured pressure decreases according to Kalman filter principle. As a result, because the state variables of the Kalman filter converge to real variables, unsteady flowrate is estimated from the state variables of the Kalman filter. Experimental calibration of the Kalman-filtering laminar flowmeter under steady-state flow condition has been performed. In this study, experiments of step response of flowrate in a pipe are conducted by constructing an experimental circuit using solenoid valves. The purpose of experiment is confirmation of a response time of the Kalman-filtering laminar flowmeter. As a result of experiments, it was shown that the response time is 0.05s.
Numerical Study of a Weight-Adjustable Buoy for Efficient Wave Energy Conversion
Authors: Tian Hao , Zhou Boyang , Zhang Zengmeng , Gong Yongjun
Published: December 2021

Heaving motion of ocean wave is a promising renewable energy source but challenging to capture with consistent conversion efficiencies. Main issue of the varying energy extraction efficiency of wave energy converters (WEC’s) is primarily caused by the variation of incident wave frequency and amplitude. Traditional design of the WEC has to account for the extreme sea conditions, leaving the WEC to work at suboptimal regions for most of the time. Due to the loss characteristics of the fluid power components, the performance and efficiency drop rapidly when moved away from the optimal working condition. In order to improve the efficiency of WEC, the buoy needs to operate at maximum amplitude most of the time. To do so, a new buoy structure based on actively controlled fluid-air ratio is proposed. Contrast to the traditional buoy for WEC’s, which has fixed density and weight, the proposed structure is capable of weight manipulation, resulting adjustable system natural frequency. MATLAB/Simulink simulation analysis is carried out to verify the feasibility of adjusting the gas-liquid ratio inside the buoy with a water hydraulic system. To resonate with the unknown incident wave, maximum power point tracking (MPPT) algorithm is proposed to control the buoy mass with trial steps for maximizing the resonating amplitude of the buoy. Initial simulation results have shown that the proposed system is capable of adjusting the natural frequency and the MPPT algorithm can increase the amplitude of the buoy motion.
Incorporating Valve Switching Losses Into a Static Optimal Control Algorithm for the Hybrid Hydraulic-Electric Architecture (HHEA)
Authors: Khandekar Aditya , Wills Jackson , Wang Meng (Rachel) , Li Perry Y.
Published: December 2021

The Hybrid Hydraulic-Electric Architecture (HHEA) has, in recent years, been proposed as an energy efficient alternative to conventional load-sensing architectures in mobile machines such as excavators and wheel-loaders. HHEA leverages the advantages of hydraulic power and electric power to eliminate throttling valves while also improving the energy and control performance of the system. The architecture utilizes a set of common pressure rails to provide a majority of power and and a small electric motor driven pump to modulate this power to meet the exact demand. Previous work has developed a computationally efficient Lagrange Multiplier approach for determining the optimal pressure rail selections that minimizes the energy losses in the system. The static model used considers only the energy use for each pressure rail selection but not the losses associated with the valves during the transition. This paper presents an approach to include the switching losses in the model and in the optimization procedure. To capture the switching losses, switching events between different rails and at various input and output flow rates were simulated with consideration of valve spool dynamics. A parameterized model that summarizes the losses is then obtained, allowing switching losses to be added to the previous energy analysis. The performance of the switching loss model was compared with reference data obtained from a high-fidelity simulation model. To incorporate the switching losses into optimal control algorithm, an efficient dynamic programming approach that prevents frequent switching is adopted in place of the Lagrange multiplier approach. The overall effect of switching losses on the energy consumption and optimal control decisions is presented. In general, switching losses contribute to about 9–10% of input energy.
Prediction, Control and Energy Analyses of Hydraulic Transformer Based Heave Compensator
Authors: Yu Huan , Fang Jinhui , Wei Jianhua , Li Shizhen , Zhang Hangjun
Published: December 2021

Heave compensators are widely used in offshore equipments to decouple the load motion from the wave induced ship motion. Hydraulic transformer based heave compensator (HTHC) can better compensate the ship’s heave in comparison with passive heave compensators (PHC) under changing sea conditions, meanwhile the accumulators’ volume is decreased significantly. Here in this paper, some further discussions about HTHC are given on the aspects of prediction, controller design and energy saving through simulation. Results turn out that heave prediction based on sliding mode observer is better than the Luenberger observer based one; chattering can be reduced through back-stepping method. The controller is robust when the load is perturbed by uncertain forces, and energy consumption of HTHC is about 56% of the one in an equal-sized hybrid active heave compensator (HAHC) meanwhile its total installed power can be reduced by 70%.
The Effect of Slotted Hole on Minimum Oil Film Thickness of Piston in Radial Piston Hydraulic Motor
Authors: Zhang Xiaolong , Zhang Junhui , Xu Bing , Yang Zhixian , Zhao Qi , Zhang Hongjuan
Published: December 2021

The cam-lobe radial-piston hydraulic motor, a multistroke low-speed high-torque motor, is widely used in large rotating machines such as winches, shield machines, and shredders, etc. There is a slotted hole on its pistons to reduce inertial force, which can simultaneously affect piston deformation. Unfortunately, piston deformation will also have an obvious impact on the oil film characteristics of the interface between pistons and cam rollers. Accordingly, in this paper, a coupled model, which combines the unsteady elastohydrodynamic lubrication model and a structural mechanics model, is established. Based on the model, the effect of the slotted hole on the minimum oil film thickness is analyzed through the dynamic simulation. The simulation results show that the slotted hole alters the oil film shape and pressure distribution. As a result, the minimum oil film thickness increases. This study could provide valuable guidance for further optimizing the piston of radial piston hydraulic motor.
Investigating the Filtration Characteristics of Direct Driven Hydraulics
Authors: Han Xu , Välimaa Jussi , Orifjonov Abdullokh , Padovani Damiano , Minav Tatiana
Published: December 2021

Direct driven hydraulics (DDH) is receiving increasing attention due to its advantages such as high energy efficiency, easy maintenance, and compactness. However, its oil contamination management has not been surveyed in detail, whereas uncontrolled oil contamination might result in extra maintenance efforts or even downtime. Therefore, this research paper analyzes the oil filtration in direct driven hydraulics through modeling and simulation to predict the filtration effects and support the filtration design. Firstly, model blocks of the filtration characteristics are built to be added to the basic DDH dynamic model. The model can hereby include the coupling effects between fluid degradation and component wear, the filtering process, and the time-varying filter performance. Secondly, the proposed model is applied to a DDH that incorporates filtration and simulated under a duty cycle for 960 hours. The DDH efficiency and control performance when considering the contaminant are revealed. Thirdly, the results are compared between different filter selections and a filtration solution is finally proposed. In conclusion, this paper illustrates the filtration effects on the efficiency, control performance, and oil contaminant level of DDH by simulation, which can hereby support the design of the DDH filtration solution. According to the simulations, the filtered DDH resulted in 96% degradation of the pump’s volumetric efficiency after 960-hour running compared to 92% when not using any filters. The extra pressure drop introduced by the filter is below 2 bar, suggesting that the introduction of a filter with 6 μm filtration level is beneficial.
Coaching Through a “Gender Lens” May Reveal Myths That Hinder Female Athletes: A Multistudy Investigation
Authors: Gosai Jyoti , Jowett Sophia , Rhind Daniel J.A.
Published: December 2021

The purpose of this multistudy paper was to explore (a) the coaching behaviors of male coaches when coaching either male or female teams through a systematic observation (Study 1) and (b) male and female coaches’ reasons for employing certain behaviors and practices when coaching female athletes through semistructured interviews (Study 2). Collectively, the findings of these two studies highlighted that coaches, either consciously or unconsciously, use a “gender lens” to coach their athletes. Study 1 findings showed that male coaches organize practice sessions (e.g., longer sessions for female than male athletes) and manifest coaching behaviors (e.g., more reinforcement for female than male athletes) that are different depending on whether they coach teams that comprise male or female athletes. Study 2 findings revealed gender biases in the approaches and styles coaches employed to coach their female and male athletes, suggesting that such methods could be limiting female athletes’ physical, social-emotional, and psychological development. This multistudy paper discusses how coaches’ good intentions to coach effectively can fall short and into a trap of gender stereotypes, leading to coaching the gender of the athletes as opposed to coaching each one athlete as an individual. The implications of these findings for practice are discussed.
Speed Improves With Eccentric Hamstring Training in Athletes of Different Maturity Status
Authors: Hammami Raouf , Gene-Morales Javier , Nebigh Ammar , Rebai Haithem , Colado Juan C.
Published: December 2021

Purpose: To investigate the effects of an eccentric hamstring strength training program (EHT) on sprint performance (10-, 20-, and 30-m sprint times) and change of direction speed (4 × 5-m shuttle run and T-Half test) in male European handball athletes at 2 maturity statuses (prepeak and postpeak height velocity [PHV]). Methods: Forty-five participants (12.68 [1.58] y) were divided into pre-PHV and post-PHV and randomly allocated to a control or intervention group, which performed a guided 2 day per week 6-week EHT of 5 exercises. A mixed-model (within- and between-factor) analysis of variance was conducted. Results: A significant effect (P < .05) of the interaction time × maturity × training was observed in the T-Half, 10, and 30 m tests. Both intervention groups significantly improved in all the tests, except in the 20 m sprint and the post-PHV in the 10 m sprint. Improvements ranged between 0.93% and 5.74% (effect size: 0.07–0.79). Both control groups yielded no improvements in almost all the tests. The improvements of both groups undergoing the intervention (pre-PHV and post-PHV) were not significantly different (only a tendency in the 10 m sprint). Conclusion: An EHT program combined with European-handball training improve change of direction and sprint performance in pre-PHV and post-PHV male players. Professionals training European handball and similar team-sport athletes should consider including EHT regardless of athlete’s maturity.
Antivirulence Bispecific Monoclonal Antibody-Mediated Protection against Pseudomonas aeruginosa Ventilator-Associated Pneumonia in a Rabbit Model
Authors: Aguiar-Alves Fábio , Le Hoan N. , Tran Vuvi G. , Gras Emmanuelle , Vu Trang T. T. , Dong Oliver X. , Quetz Josiane Silva , Cheng Lily I. , Yu Li , Sellman Bret R. , Stover Charles K. , DiGiandomenico Antonio , Diep Binh An
Published: December 2021

Ventilator-associated pneumonia is an important clinical manifestation of the nosocomial pathogen
Pseudomonas aeruginosa
. We characterized the correlates of protection with MEDI3902, a bispecific human IgG1 monoclonal antibody that targets the
P. aeruginosa
type 3 secretion system PcrV protein and the Psl exopolysaccharide, in a rabbit model of ventilator-associated pneumonia using lung-protective, low-tidal-volume mechanical ventilation.
Cefepime Precision Dosing Tool: from Standard to Precise Dose Using Nonparametric Population Pharmacokinetics
Authors: Alshaer Mohammad H. , Goutelle Sylvain , Santevecchi Barbara A. , Shoulders Bethany R. , Venugopalan Veena , Cherabuddi Kartikeya , Liu Jiajun , Kiel Patrick J. , Roberts Jason A. , Sime Fekade Bruck , Scheetz Marc H. , Neely Michael N. , Peloquin Charles A.
Published: December 2021

Cefepime is the second most common cephalosporin used in U.S. hospitals. We aim to develop and validate a cefepime population pharmacokinetic (PK) model and integrate it into a precision dosing tool for implementation.
Transcriptional Profiling of Early and Late Phases of Bovine Tuberculosis
Authors: Abdelaal Hazem F. M. , Thacker Tyler C. , Wadie Bishoy , Palmer Mitchell V. , Talaat Adel M.
Published: December 2021

Bovine tuberculosis, caused byMycobacterium tuberculosisvar.bovis(M. bovis), is an important enzootic disease affecting mainly cattle, worldwide. Despite the implementation of national campaigns to eliminate the disease, bovine tuberculosis remains recalcitrant to eradication in several countries.
HprSR Is a Reactive Chlorine Species-Sensing, Two-Component System in Escherichia coli
Authors: El Hajj Sara , Henry Camille , Andrieu Camille , Vergnes Alexandra , Loiseau Laurent , Brasseur Gaël , Barré Romain , Aussel Laurent , Ezraty Benjamin
Published: December 2021

Understanding how bacteria respond to oxidative stress at the molecular level is crucial in the fight against pathogens. HOCl is one of the most potent industrial and physiological microbicidal oxidants.
Concomitant health benefits package design and research prioritisation: development of a new approach and an application to Malawi
Authors: Schmitt Laetitia , Ochalek Jessica , Claxton Karl , Revill Paul , Nkhoma Dominic , Woods Beth
Published: December 2021

Health benefits packages (HBPs) are increasingly used in many countries to guide spending priorities on the path towards universal health coverage. Their design is, however, informed by an uncertain evidence base but research funds available to address this are limited. This gives rise to the question of which piece of research relating to the cost-effectiveness of interventions would most contribute to improving resource allocation. We propose to incorporate research prioritisation as an integral part of HBP design. We have, therefore, developed a framework and a freely available companion stand-alone tool, to quantify in terms of net disability-adjusted life-years (DALYs) averted, the value of research for the interventions considered for inclusion in a package. Using the tool, the framework can be implemented using sensitivity analysis results typically reported in cost-effectiveness studies. To illustrate the framework, we applied the tool to the evidence base that informed the Malawi Health Sector Strategic Plan 2017–2022. Out of 21 interventions considered, 8 investment decisions were found to be uncertain and three showed strong potential for research to generate large health gains: ‘male circumcision’, ‘community-management of acute malnutrition in children’ and ‘isoniazid preventive therapy in HIV +individuals’, with a potential to avert up to 65 762, 36 438 and 20 132 net DALYs, respectively. Our work can help set research priorities in resource-constrained settings so that research funds are invested where they have the largest potential to impact on the population health generated via HBPs.
Child nutritional status as screening tool for identifying undernourished mothers: an observational study of mother–child dyads in Mogadishu, Somalia, from November 2019 to March 2020
Authors: Zacks Rachael , Ververs Mija , Hwang Cindy , Mahdi Adan , Leidman Eva
Published: December 2021

Background

Active screening of only pregnant and lactating mothers (PLMs) excludes other mothers of reproductive age susceptible to undernutrition. Our analysis evaluated if mothers presenting with wasted children were more likely to be undernourished themselves.

Methods

The observational study enrolled mother and child dyads presenting to an outpatient facility in Mogadishu, Somalia, between November 2019 and March 2020. Trained nurses recorded lower extremity oedema for children aged 6–59 months, parity and gestational status for women aged 19–50 years and age, access to care, height/length, mid-upper arm circumference (MUAC) and weight for both. Weight-for-height z-score (WHZ) for children and body mass index (BMI) for mothers were calculated using standard procedures. Wasting was defined as WHZ <−2, MUAC <12.5 cm and/or presence of oedema for children. Undernutrition was defined as MUAC <23 cm for PLMs and BMI <18.5 kg/m2for neither pregnant nor lactating mothers (non-PLMs). Four multivariable linear regression models were fit to evaluate maternal anthropometric indicators (BMI or MUAC) given child anthropometric indicators (MUAC or WHZ), adjusting for maternal age, parity and gestational status.

Results

A total of 93.6% (2142/2288) of enrolled dyads met inclusion criteria. Wasting was observed among 57.5% of children; 20.2% of pregnant mothers, 20.0% of lactating mothers and 7.95% of non-PLMs were undernourished. Models suggest significant, positive associations between child and maternal anthropometrics; a one-unit increase in WHZ and a 1 cm increase in child MUAC were associated with 0.22 kg/m2(95% CI 0.22 to 0.24) and 0.19 kg/m2(95% CI 0.16 to 0.21) increases in maternal BMI, respectively, and 0.20 cm (95% CI 0.18 to 0.22) and 0.24 cm (95% CI 0.23 to 0.25) increases in maternal MUAC, respectively. Adjusted R2values were low (range 0.06–0.10).

Conclusions

Undernutrition among non-PLMs illustrates the importance of expanding screening. However, while significant, the strength of association between mother and child anthropometrics does not support child nutritional status as a screening tool for identifying at-risk mothers.
Risk assessment of metabolic syndrome prevalence involving sedentary occupations and socioeconomic status
Authors: Chen Ming-Shu , Chiu Chi-Hao , Chen Shih-Hsin
Published: December 2021

Objectives

To determine whether occupation type, distinguished by socioeconomic status (SES) and sedentary status, is associated with metabolic syndrome (MetS) risk.

Methods

We analysed two data sets covering 73 506 individuals. MetS was identified according to the criteria of the modified Adult Treatment Panel III. Eight occupational categories were considered: professionals, technical workers, managers, salespeople, service staff, administrative staff, manual labourers and taxi drivers; occupations were grouped into non-sedentary; sedentary, high-SES; and sedentary, non-high-SES occupations. A multiple logistic regression was used to determine significant risk factors for MetS in three age-stratified subgroups. R software for Windows (V.3.5.1) was used for all statistical analyses.

Results

MetS prevalence increased with age. Among participants aged ≤40 years, where MetS prevalence was low at 6.23%, having a non-sedentary occupation reduced MetS risk (OR=0.88, p<0.0295). Among participants aged >60 years, having a sedentary, high-SES occupation significantly increased (OR=1.39, p<0.0247) MetS risk.

Conclusions

The influence of occupation type on MetS risk differs among age groups. Non-sedentary occupations and sedentary, high-SES occupations decrease and increase MetS risk, respectively, among younger and older adults, respectively. Authorities should focus on individuals in sedentary, high-SES occupations.
Structural equation model of physical activity in Turkish schoolchildren: an application of the integrated behavioural model
Authors: Mirzayi Chloe , Ferris Emily , Ozcebe Hilal , Swierad Ewelina , Arslan Umut , Ünlü Hande , Araz Ozgur , Yardim Mahmut Saadi , Üner Sarp , Bilir Nazmi , Huang Terry T
Published: December 2021

Objectives

Childhood obesity is increasingly prevalent in the developing world including Turkey. This study examined constructs of the integrated behavioural model associated with physical activity in a sample of schoolchildren in Ankara, Turkey using structural equation modelling.

Design

Cross-sectional survey by probability sampling.

Setting

Fifteen schools of different socioeconomic strata in Ankara, Turkey with grade 4 students.

Participants

2066 (969 girls and 1097 boys) grade 4 schoolchildren and their parents selected using a probability-based sampling frame.

Primary outcome measures

Three primary outcomes were used: moderate-to-vigorous physical activity, team sport participation, sedentary behaviour.

Results

Data were collected from 2066 fourth-grade children from schools of three socioeconomic strata. Missing data were imputed using multiple imputation. To examine the integrated behavioural model, a structural equation model containing latent constructs for physical activity outcome expectancies, self-efficacy, home environment and social norms were fitted with the three outcomes above. Adequate model fit was achieved in the structural equation model (χ2=1821.97, df=872, p<0.001, Comparative Fit Index=0.91, Tucker Lewis Index=0.91, root mean square error of approximation=0.02, standardised root mean square residual=0.04). All scale items were significantly associated with their respective latent constructs (all p<0.001). Several significant pathways between latent constructs and outcomes of interest were observed (p<0.05). Self-efficacy was positively associated with moderate-to-vigorous physical activity (p<0.001) and team sport participation (p<0.001) and negatively associated with sedentary behaviour (p<0.001). Negative outcome expectancies were negatively associated with moderate-to-vigorous physical activity (p<0.01) and sedentary behaviour (p<0.01) while positive outcome expectancies were positively associated with team sport behaviour (p<0.001) and negatively associated with sedentary behaviour (p<0.05). Home support was positively associated with moderate-to-vigorous physical activity (p<0.01) and team sport participation (p<0.05). Finally, physical activity social norms were negatively associated with sedentary behaviour only (p<0.05).

Conclusions

This study supported the extension to Turkish children of the integrated behavioural model in relation to physical activity behaviours. Results illustrate multiple targets for interventions to increase physical activity.
Population-based study of the association between asthma and exogenous female sex hormone use
Authors: Jung Won Jai , Lee Sang Yeub , Choi Sue In , Kim Byung-Keun , Lee Eun Joo , Choi Jimi
Published: December 2021

Objectives

Several studies have suggested the influence of exogenous hormones on asthma, but the results are still conflicting. Moreover, there has been little associated research on Asian population. This study aimed to assess the association between use of exogenous female sex hormones and asthma in Korean women.

Design

Korea National Health and Nutrition Examination Survey (KNHANES) is a nationwide programme to assess national health and nutritional status in Korea. A population-based study was conducted to analyse the relationship between self-reported asthma and exogenous hormones using the KNHANES between 2007 and 2012.

Participants

The study sample included 6874 premenopausal and 4912 postmenopausal women aged 30–65.

Outcome measures

KNHANES data comprised health interviews and physical examinations. Questionnaires regarding asthma, reproductive factors and exogenous hormones were included.

Results

Among postmenopausal women, 3.4% reported doctor-diagnosed asthma. Hormone replacement therapy (HRT) was associated with increased odds of doctor-diagnosed asthma (OR 1.56; 95% CI 1.04 to 2.35), while the association between HRT and wheeze in the last 1 year was not significant (OR 1.37; 95% CI 0.95 to 1.96). In premenopausal women, the prevalence of asthma was 2.3%. Use of oral contraceptives (OCs) was associated with an increased odds of doctor-diagnosed asthma (OR 1.67; 95% CI 1.01 to 2.76) and wheeze in the last 1 year (OR 1.88; 95% CI 1.31 to 2.69). These associations were dominant among non-obese women (body mass index <25 kg/m2; OR 2.36; 95% CI 1.34 to 4.17 for asthma and OR 2.15; 95% CI 1.43 to 3.23 for wheeze).

Conclusions

HRT and OCs were associated with increased asthma in postmenopausal and premenopausal women, respectively. The association between OC use and asthma was strong in non-obese premenopausal women.
Prevalence, classification, risk factors and outcome impact of delirium in patients with COVID-19: a meta-analysis protocol for systematic review
Authors: Lou Baohui , Guo Jingfei , Liu Yue , Xiong Chao , Shi Jia , Zhou Chenghui
Published: December 2021

Introduction

Previous studies have shown mixed results that delirium may result in a high risk of adverse clinical outcomes in patients with COVID-19. The aim of this meta-analysis is to summarise the evidence of prevalence, classification, risk factors and outcomes impact of delirium in adult patients with COVID-19.

Methods

A systematic search will be performed in PubMed, EMBase, ISI Knowledge via Web of Science and preprint databases (MedRxiv and BioRxiv) (from inception until June 2021) to identify all cohort studies concerning delirium in adult patients with COVID-19. The primary outcome will be the prevalence of delirium with different classifications (hyperactive, hypoactive or mixed type). The secondary outcomes will include the association of risk factors and the association with all-cause mortality during hospitalisation. Univariable or multivariable meta-regression and subgroup analyses will be conducted for the study design and patient characteristics. Sensitivity analyses were used to assess the robustness of our results by removing each included study at one time to obtain and evaluate the remaining overall estimates of primary and secondary outcomes.

Ethics and dissemination

Ethical approval is not an essential element for the systematic review protocol in accordance with the Institutional Review Board /Independent Ethics Committee of Beijing Hospital. This meta-analysis will be disseminated through a peer-reviewed journal for publication.

PROSPERO registration number

CRD42020224871.
Epidemiological characteristics and risk factors of biliary atresia: a case–control study
Authors: Jiang Jingying , Wan Rou , He Shiwei , Wu Ying , Shen Zhen , Chen Gong , Sun Song , Yan Weili , Zheng Shan
Published: December 2021

Objectives

Biliary atresia (BA) is regarded as a serious neonatal hepatobiliary disease, and its aetiology and pathogenesis remain unclear. Epidemiological studies are limited, especially for the data from China. This study aims to explore risk factors of BA and provide new evidence to improve understanding of its aetiology.

Design

This is a case–control study from 1 January 2015 to 31 December 2016.

Setting

Cases were consecutively recruited from an urban tertiary care academic children’s hospital in Shanghai, China, while the controls were recruited from a community hospital in Shanghai through a random sampling system.

Participants

721 patients suspected for BA who planned to take the diagnostic surgery were enrolled preoperatively. 613 were diagnosed with BA and recruited into the case group. Meanwhile, 688 infants without any observed major congenital anomalies or jaundice were enrolled. Finally, 594 valid questionnaires from the case group and 681 from the control group were obtained.

Primary and secondary outcome measures

Standardised questionnaires were used for data collection. Multivariate logistic regression analysis was performed to evaluate associations reported as ORs and precision, by adjusting covariates.

Results

Anxiety or stress during pregnancy was strongly associated with increased risk of BA (OR 8.36 (95% CI: 4.08 to 17.15); p<0.001), respectively. Lower birth weight, fathers from ethnic minorities of China, older age of fathers, lower income of parents, and exposure to infection, diseases and medication during pregnancy all made differences.

Conclusions

Social factors including the educational and economic background and its related anxiety and stress during pregnancy might be noticed in the occurrence of BA. Maternal infections during pregnancy in the prevalence of BA were demonstrated.

Trial registration number

ChiCTR-IPR-15005885.
Chlorhexidine oral rinses for symptomatic COPD: a randomised, blind, placebo-controlled preliminary study
Authors: Pragman Alexa A , Fieberg Ann M , Reilly Cavan S , Wendt Christine
Published: December 2021

Objectives

Determine the effect of twice-daily chlorhexidine oral rinses on oral and lung microbiota biomass and respiratory symptoms.

Setting

Single centre.

Participants

Participants were aged 40–85 with chronic obstructive pulmonary disease (COPD) and chronic productive cough or COPD exacerbation within the last year. Exclusions included antibiotics in the previous 2 months and/or those with less than four teeth. Forty-four participants were recruited and 40 completed the study.

Intervention

Participants were randomised 1:1 to twice-daily 0.12% chlorhexidine oral rinses versus placebo for 2 months along with daily diaries. St. George’s Respiratory Questionnaire (SGRQ), blood tests, oral rinse and induced sputum were collected at randomisation and the final visit.

Primary and secondary outcomes

Primary outcome was a change in oral and sputum microbiota biomass. Secondary outcomes included: sputum and oral microbiota Shannon and Simpson diversity and taxonomy; inflammatory markers; Breathlessness, Cough and Sputum Scale and SGRQ scores.

Results

Neither the oral microbiota nor the sputum microbiota biomass decreased significantly in those using chlorhexidine compared with placebo (oral microbiota mean log10difference (SE)=−0.103 (0.23), 95% CI −0.59 to 0.38, p=0.665; sputum microbiota 0.80 (0.46), 95% CI −0.15 to 1.75, p=0.096). Chlorhexidine decreased both oral and sputum microbiota alpha (Shannon) diversity (linear regression estimate (SE) oral: −0.349 (0.091), p=0.001; sputum −0.622 (0.169), p=0.001). Chlorhexidine use did not decrease systemic inflammatory markers compared with placebo (C reactive protein (chlorhexidine 1.8±7.5 vs placebo 0.4±6.8, p=0.467), fibrinogen (22.5±77.8 vs 10.0±77.0, p=0.406) or leucocytes (0.2±1.8 vs 0.5±1.8, p=0.560)). Chlorhexidine use decreased SGRQ scores compared with placebo (chlorhexidine −4.7±8.0 vs placebo 1.7±8.9, p=0.032).

Conclusions

We did not detect a significant difference in microbiota biomass due to chlorhexidine use. Chlorhexidine decreased oral and sputum microbiota alpha diversity and improved respiratory health-related quality of life compared with placebo.

Trial registration

NCT02252588.
Effectiveness and cost-effectiveness of a structured social coaching intervention for people with psychosis (SCENE): protocol for a randomised controlled trial
Authors: Giacco Domenico , Chevalier Agnes , Patterson Megan , Hamborg Thomas , Mortimer Rianna , Feng Yan , Webber Martin , Xanthopoulou Penny , Priebe Stefan
Published: December 2021

Introduction

People with psychosis tend to have smaller social networks than both people in the general population and other people with long-term health conditions. Small social networks are associated with poor quality of life. Preliminary evidence suggests that coaching patients to increase their social contacts may be effective. In this study, we assessed whether structured social coaching improves the quality of life of patients with psychosis (primary outcome) compared with an active control group, receiving information on local social activities.

Methods and analysis

A structured social coaching intervention was developed based on the literature and refined through stakeholder involvement. It draws on principles from motivational interviewing, solution focused therapy and structured information giving. It is provided over a 6-month period and can be delivered by a range of different mental health professionals. Its effectiveness and cost-effectiveness are assessed in a randomised controlled trial, compared with an active control group, in which participants are given an information booklet on local social activities. Participants are aged 18 or over, have a primary diagnosis of a psychotic disorder (International Classification of Disease: F20–29) and capacity to provide informed consent. Participants are assessed at baseline and at 6, 12 and 18 months after individual randomisation. The primary outcome is quality of life at 6 months (Manchester Short Assessment of Quality of Life). We hypothesise that the effects on quality of life are mediated by an increase in social contacts. Secondary outcomes are symptoms, social situation and time spent in social activities. Costs and cost-effectiveness analyses will consider service use and health-related quality of life.

Ethics and dissemination

National Health Service REC London Hampstead (19/LO/0088) provided a favourable opinion. Findings will be disseminated through a website, social media, scientific papers and user-friendly reports, in collaboration with a lived experience advisory panel.

Trial registration number

ISRCTN15815862.
Differences in risk factors associated with single and multiple concurrent forms of undernutrition (stunting, wasting or underweight) among children under 5 in Bangladesh: a nationally representative cross-sectional study
Authors: Chowdhury Mohammad Rocky Khan , Khan Hafiz T A , Rashid Mamunur , Kabir Russell , Islam Sazin , Shariful Islam Md , Kader Manzur
Published: December 2021

Objectives

The study aims to differentiate the risk factors of single and multiple concurrent forms of undernutrition among children under 5 in Bangladesh.

Design

A nationally representative cross-sectional study.

Setting

Bangladesh.

Respondents

Children age under 5 years of age.

Outcome measure

This study considered two dichotomous outcomes: single form (children without single form and with single form) and multiple concurrent forms (children without multiple forms and with multiple forms) of undernutrition.

Statistical analysis

Adjusted OR (AOR) and CI of potential risk factors were calculated using logistic regression analysis.

Results

Around 38.2% of children under 5 in Bangladesh are suffering from undernutrition. The prevalence of multiple concurrent forms and single form of child undernutrition was 19.3% and 18.9%, respectively. The key risk factors of multiple concurrent forms of undernutrition were children born with low birth weight (AOR 3.76, 95% CI 2.78 to 5.10); children in the age group 24–35 months (AOR 2.70, 95% CI 2.20 to 3.30) and in the lowest socioeconomic quintile (AOR 2.57, 95% CI 2.05 to 3.23). In contrast, those children in the age group 24–35 months (AOR 1.94, 95% CI 1.61 to 2.34), in the lowest socioeconomic quintile (AOR 1.79, 95% CI 1.45 to 2.21) and born with low birth weight (AOR 1.52, 95% CI 1.11 to 2.08) were significantly associated with a single form of undernutrition. Parental education, father’s occupation, children’s age and birth order were the differentiating risk factors for multiple concurrent forms and single form of undernutrition.

Conclusion

One-fifth of children under 5 years of age are suffering multiple concurrent forms of undernutrition, which is similar to the numbers suffering the single form. Parental education, father’s occupation, children’s age and birth order disproportionately affect the multiple concurrent forms and single form of undernutrition, which should be considered to formulate an evidence-based strategy for reducing undernutrition among these children.
Analysis ofCYP2C19genetic variants with ischaemic events in UK patients prescribed clopidogrel in primary care: a retrospective cohort study
Authors: Pilling Luke C , Türkmen Deniz , Fullalove Hannah , Atkins Janice L , Delgado Joao , Kuo Chia-Ling , Kuchel George A , Ferrucci Luigi , Bowden Jack , Masoli Jane A H , Melzer David
Published: December 2021

Objective

To determine whetherCYP2C19loss-of-function (LoF) alleles increase risk of ischaemic stroke and myocardial infarction (MI) in UK primary care patients prescribed clopidogrel.

Design

Retrospective cohort analysis.

Setting

Primary care practices in the UK from January 1999 to September 2017.

Participants

7483 European-ancestry adults from the UK Biobank study with genetic and linked primary care data, aged 36–79 years at time of first clopidogrel prescription.

Interventions

Clopidogrel prescription in primary care, mean duration 2.6 years (range 2 months to 18 years).

Main outcome measure

Hospital inpatient-diagnosed ischaemic stroke, MI or angina while treated with clopidogrel.

Results

28.7% of participants carried at least one CYP2C19LoF variant. LoF carriers had higher rates of incident ischaemic stroke while treated with clopidogrel compared with those without the variants (8 per 1000 person-years vs 5.2 per 1000 person-years; HR 1.53, 95% CIs 1.04 to 2.26, p=0.031). LoF carriers also had increased risk of MI (HR 1.14, 95% CI 1.04 to 1.26, p=0.008). In combined analysis LoF carriers had increased risk of any ischaemic event (stroke or MI) (HR 1.17, 95% CI 1.06 to 1.29, p=0.002). Adjustment for aspirin coprescription produced similar estimates. In lifetables using observed incidence rates, 22.5% (95% CI 14.4% to 34.0%) ofCYP2C19LoF carriers on clopidogrel were projected to develop an ischaemic stroke by age 79 (oldest age in the study), compared with 15.4% (95% CI 11.4% to 20.5%) in non-carriers, that is, 7.1% excess stroke incidence in LoF carriers by age 79.

Conclusions

A substantial proportion of the UK population carry genetic variants that reduce metabolism of clopidogrel to its active form. In family practice patients on clopidogrel,CYP2C19LoF variants are associated with substantially higher incidence of ischaemic events. Genotype-guided selection of antiplatelet medications may improve outcomes in patients carryingCYP2C19genetic variants.
Determinants of continued maternal care seeking during pregnancy, birth and postnatal and associated neonatal survival outcomes in Kenya and Uganda: analysis of cross-sectional, demographic and health surveys data
Authors: Arunda Malachi Ochieng , Agardh Anette , Asamoah Benedict Oppong
Published: December 2021

Objectives

To examine how maternal and sociodemographic factors determine continued care-seeking behaviour from pregnancy to postnatal period in Kenya and Uganda and to determine associated neonatal survival outcomes.

Design

A population-based analysis of cross-sectional data using multinomial and binary logistic regressions.

Setting

Countrywide, Kenya and Uganda.

Participants

Most recent live births of 24 502 mothers within 1–59 months prior to the 2014–2016 Demographic and Health Surveys.

Outcomes

Care-seeking continuum and neonatal mortality.

Results

Overall, 57% of the mothers had four or more antenatal care (ANC) contacts, of which 73% and 41% had facility births and postnatal care (PNC), respectively. Maternal/paternal education versus no education was associated with continued care seeking in majority of care-seeking classes; relative risk ratios (RRRs) ranged from 2.1 to 8.0 (95% CI 1.1 to 16.3). Similarly, exposure to mass media was generally associated with continued care seekin; RRRs ranged from 1.8 to 3.2 (95% CI 1.2 to 5.4). Care-seeking tendency reduced if a husband made major maternal care-seeking decisions. Transportation problems and living in rural versus urban were largely associated with lower continued care use; RRR ranged from 0.4 to 0.7 (95% CI 0.3 to 0.9). The twolowestcare-seeking categories with no ANC and no PNC indicated the highest odds for neonatal mortality (adjusted OR 4.2, 95% CI 1.6 to 10.9). 23% neonatal deaths were attributable to inadequate maternal care attendance.

Conclusion

Strategies such as mobile health specifically for promoting continued maternal care use up to postnatal could be integrated in the existing structures. Another strategy would be to develop and employ a brief standard questionnaire to determine a mother’s continued care-seeking level during the first ANC visit and to use the information to close the care-seeking gaps. Strengthening the community health workers system to be an integral part of promoting continued care seeking could enhance care seeking as a stand-alone strategy or as a component of aforementioned suggested strategies.
Health-seeking behaviours in a malaria endemic district in Lao People’s Democratic Republic: a mixed methods study
Authors: Ong Ken Ing Cherng , Khattignavong Phonepadith , Keomalaphet Sengdeuane , Iwagami Moritoshi , Brey Paul , Kano Shigeyuki , Jimba Masamine
Published: December 2021

Objectives

This mixed methods study was conducted to explore the barriers and facilitators for health-seeking behaviours in a malaria endemic district in Lao PDR.

Design

A convergent mixed methods design.

Setting

Two malaria endemic villages in Thapangthong district, Savannakhet Province, Lao PDR.

Participants

Villagers and healthcare workers in the two villages in Thapangthong district.

Methods

In the quantitative part, a pretested questionnaire was used to identify the health-seeking behaviours of the villagers. In the qualitative part, focus group discussions were employed to explore health-seeking behaviours of the villagers and in-depth interviews were used to explore the perceptions of the healthcare workers. Descriptive statistics were computed and multiple logistic regressions were used to identify the factors associated with perceived severity and perceived susceptibility. Thematic analysis was used to analyse the qualitative data. Quantitative and qualitative results were integrated in joint displays.

Results

In the quantitative part, data were collected from 313 villagers from both villages. For malaria, 96.0% and 98.2% of villagers from villages A and B, respectively, would first seek treatment at public health facilities. Villagers who have not experienced malaria before were more likely to perceive that the consequences of malaria were serious compared with those who have experienced malaria before (adjusted OR=1.69, 95% CI: 1.03 to 2.75). However, qualitative data showed that villagers faced problems such as lack of medicines and medical equipment. Healthcare workers also mentioned the lack of manpower and equipment in the in-depth interviews. Nevertheless, villagers still preferred to seek treatment at the health center as the National Health Insurance was introduced.

Conclusions

Public health facility usage was high but barriers existed. Effective policy and enabling environment such as the introduction of the National Health Insurance could help accelerate the progress towards the malaria elimination goal. Moreover, the benefits could go beyond the context of malaria.