bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Model-Based Steering Control for Hydra-Power Articulated Steering Vehicles
Authors: Gao Lulu , Jin Chun , Liu Yuchao , Ma Fei , Feng Zhipeng
Published: October 2020

The hydra-power articulated steering vehicles possess brilliant maneuverability and efficiency, and they were widely applied in mining, construction, agriculture, and forestry. However, the steering characteristic also deduced a serious handling stability problem of this type of vehicle, i.e., oscillation in yaw motion. Previous research only analyzed the stability of the vehicle dynamical system or provided a passive structural method to suppress the oscillation of articulated vehicles. This work presents a novel model-based steering control of articulated steering vehicles. A coupled nonlinear dynamic model was established firstly, in which nonlinear models of the hydraulic system and dynamic model of articulated frames were included. Then the coupled model was validated in time and frequency domain by a field test. The susceptibility of different factors of the system oscillation was investigated by simulation based on the validated model. On this foundation, an optimized scheme of the hydraulic steering system was provided. Further a novel control strategy, in which the articulation angle and corresponding angular velocity were considered together as the control variables of the system, was embedded into the optimized system. Comparing results in dynamic responses of articulated frames, ripples in the hydraulic steering system shown the effectiveness and superiority of the presented method.
Analogy Between Hydraulic Transformers and Variable-Speed Pumps
Authors: Schmidt Lasse , Ketelsen Søren , Mommers Robin , Achten Peter
Published: October 2020

The increasing focus on energy efficient systems and energy recuperation functionalities calls for multi actuator hydraulic systems to be tightly integrated with regards to energy distribution. Such systems need to allow power to pass back and forth between loads and the supply, while also enabling the ability to store energy. Here two approaches are obvious; namely the usage of hydraulic transformers interconnected via common pressure rails containing accumulators, and variable-speed pumps interconnected via a common electric dc-bus containing capacitors and/or batteries, both having the potential for energy storage and power sharing. A main question is when to apply which of these technologies, when considering specific requirements to actuator dynamics and control features. This paper presents an investigation into the analogy between hydraulic transformers and variable-speed pumps. The investigation takes offset in model based analyses of these technologies regarding their actuation dynamics related to torque generation, input-to-output pressure dynamics with and without a cylinder load. Finally a numerical study is presented, verifying and comparing their transient characteristics and energy losses. It is found that, disregarding the conventional speed control loop in variable-speed pumps, these are in fact equivalent with hydraulic transformers regarding secondary control abilities, dynamics and energy recovery, wheres hydraulic transformers generally must be expected to be more efficient than variable-speed pumps.
Tribotronics in Electro-Hydraulic Actuator Technology: Improving Durability by Control
Authors: Grønkær Nikolaj , Johansen Per , Hansen Kenneth Vorbøl , Schmidt Lasse
Published: October 2020

A trend in industry and academia is the design of variable-speed pump drives for use in hydraulic supply units, actuation of hydraulic cylinders and so forth, due to the potential of highly limited throttling. A main drawback in existing variable-speed pump drives is the operation of pumps at high loads and low shaft speeds, potentially increasing wear in pump bearings, especially in pumps with journal bearings. Such journal bearings rely on hydrodynamic lubrication films created by the rotation of the pump, which is minimised or removed completely when the pump shaft speed is in the lower range with a high load. The purpose of the study presented is to investigate how these conditions limit the operation of variable-speed pump drives, and how these challenges may be overcome. The study takes offset in the establishment of a wear rate constructed from a risk factor in the form of the Ocvirk number and an impact factor developed from Archard’s wear law. With this wear rate, a novel control method targeting the best possible operating conditions for the pump bearings is proposed, when applied to a simple variable-speed drive. Lastly, the consequence of applying the proposed control method on the energy efficiency is investigated. Numerical results demonstrate that the proposed control method reduces the wear rate and hereby the risk of an early pump failure, however, on the cost of a generally reduced energy efficiency.
Underwater Flexible Manipulator Double-Loop Feedback Control Based on Built-in Binocular Vision and Displacement Sensor
Authors: Yang Chen , Xu He , Li Xin , Wang Haihang , Yu Fengshu
Published: October 2020

A real-time and effective double-loop feedback control system for underwater flexible manipulators is raised in this paper. The research object is a kind of underwater flexible manipulator driven by McKibben water hydraulic artificial muscle (WHAM) that can grasp, swallow, and disgorge target objects in its interior space. To make up for the lack of flexibility, an underwater flexible manipulator collaborative working strategy is proposed. A more flexible and smaller flexible manipulator is placed inside the flexible manipulator to assist it in performing difficult underwater works. The control system feeds back the position of internal objects through a built-in binocular camera and the working state of the manipulator through displacement sensors. The control system setups including underwater flexible manipulator subsystem, hydraulic drive subsystem, PLC control subsystem, displacement sensor subsystem, built-in binocular vision subsystem, and upper computer subsystem is built. PYTHON-based built-in binocular vision software and C++-based underwater flexible manipulator control software are also developed to facilitate observation and recording. The underwater flexible manipulator collaborative experiment is designed to verify the performance of the control system and the control algorithm.
Review of Gear Pump Development at NRL
Authors: Williams Logan T.
Published: October 2020

Research into hydraulic quadrupeds at the US Naval Research Laboratory (NRL) has created the demand for in-house development of miniaturized hydraulic components, including pumps. As part of this effort to develop a miniaturized hydraulic powertrain, external gear pumps were examined, designed, and iterated upon to create an efficient pump package with a small form factor (1.5 × 1.6 × 1.8 inches). The evolution of the pump design has touched every component of the pump and has resulted in many practical design guidelines, novel pump components, and improved pump analysis tools. The original goal of developing the capability for integrated hydraulic powertrain components, such as embedding the pump into the quadruped’s hydraulic manifold, was to enable further compaction and streamlined system development. An additional result of the project was the accumulation of gear pump design fundamentals and lessons learned that can benefit any pump designer.
Demonstration of Efficient Energy Recovery Systems Using Digital Displacement® Hydraulics
Authors: Hutcheson John , Abrahams Daniel , Macpherson Jill , Caldwell Niall , Rampen Win
Published: October 2020

Heavy off-road vehicles using conventional hydraulic systems waste significant energy through the throttling of fluid to control the motion of their actuators. This paper demonstrates how Digital Displacement® Pump Motors (DDPMs) can be used to enable efficient hydraulic energy recovery systems for these vehicles by controlling the motion of actuators directly without the need of throttling.

Experiments were carried out on a test rig consisting of a 10 tonne boom supported by a hydraulic ram designed to mimic the setup of a heavy off-road vehicle. In order to demonstrate the DDPM’s potential for energy recovery systems the round-trip efficiency was measured by lifting and lowering the boom. The round-trip efficiency was taken to be the ratio of the mechanical energy output from the DDPM, when motoring to lower the boom, to the mechanical energy input to the DDPM, when pumping to raise the boom, over a known ram extension. The results showed measured round-trip efficiencies of between 63% and 87% over a range of pressures, shaft speeds and displacement fractions.

Measured data obtained during the test was used to simulate the test using different system architectures and components to determine the energy efficiency. Both load sense and displacement controlled systems were simulated using both swashplate and Digital Displacement pumps. Comparison showed that the Digital Displacement systems used between 1.1 and 10.8 times less energy than the equivalent swashplate based systems. This work forms the basis for further development of energy recovery system architectures using DDPMs. Future challenges include development of the actuator control valves and transformers required to implement such systems.
Energy Efficient Excavator Hydraulic Systems With Digital Displacement® Pump-Motors and Digital Flow Distribution
Authors: Macpherson Jill , Williamson Christopher , Green Matthew , Caldwell Niall
Published: October 2020

Environmental and economic factors are driving the development of more fuel efficient off-highway vehicles. The pathway to fuel savings of greater than 50% in an excavator application through utilisation of system architectures unlocked by Digital Displacement technology is presented.

Pump flow distribution using digital valves instead of traditional proportional control valves is demonstrated experimentally. The “Workbus” power distribution scheme is demonstrated on a small scale backhoe arm on a laboratory test rig. These tests do not include hydraulic energy recovery.

A backward-facing simulation of an 18 tonne excavator is described. The simulation uses input data collected from grading and lorry loading duty cycles. Applying the workbus system architecture to the excavator in simulation, fuel savings of 31% to 48% are realized. With the addition of energy recovery capability via Digital Displacement Pump-Motors, simulated fuel savings are 53% to 58% compared to the original excavator hydraulic system.
Optimal Control and Energy-Saving Analysis of Common Pressure Rail Architectures: HHEA and STEAM
Authors: Siefert Jacob , Li Perry Y.
Published: October 2020

In recent years several novel hydraulic architectures have been proposed with the intention of significantly increasing system efficiency. Two of these architectures, Steigerung der Energieefflzienz in der Arbeitshydraulik mobiler Arbeitsmaschinen (STEAM), and the Hybrid Hydraulic-Electric Architecture (HHEA), use a system of multiple common pressure rails (CPRs) to serve the multiple degrees-of-freedom of the machine. The key difference is that STEAM throttles hydraulic power from these rails while HHEA combines electric and hydraulic power to meet actuator demands. As a throttle-less architecture, HHEA is expected to save more energy than STEAM at the expense of added complexity. Therefore, it is useful to quantify this additional energy saving.

Both systems have discrete operational choices corresponding to how the CPRs are utilized for each actuator. It is necessary to determine optimal operation for each of these architectures for analysis and fair comparison. Techniques for optimal operation of the HHEA have been developed previously from the Langrange multiplier method. Applying the same optimal control method to STEAM encountered some technical challenge leading to the optimal control algorithm not being able to satisfy certain constraints. The issue is analyzed and solved by adding noise to the optimization.

Using this proposed algorithm, case studies are performed to compare the energy-saving potentials of STEAM and HHEA for two sizes of excavators and a wheel-loader performing representative duty cycles. The baseline is a standard load-sensing architecture. Results show that STEAM and HHEA can reduce energy consumption between 35–65% and 50–80% respectively.
Hydraulic Effort and the Efficiencies of Pump and Motors With Compressible Fluid
Authors: Li Perry Y. , Barkei Jonathan (Hans)
Published: October 2020

When hydraulic fluid is compressible, the usual formula of hydraulic power being the product of pressure (p) and volumetric flow Q, which accounts only for the flow work, is not sufficient. By deriving an explicit formula for the stored compressible energy in accordance with the possibly pressure-dependent bulk modulus, a hydraulic effort (with symbol Φ) is defined to be the sum of the fluid pressure and the compressible energy density at that pressure. It is shown that Φ is the conjugate variable to volumetric flow (Q) such that that the compressible hydraulic power flow is the product Φ(p)Q.

With proper understanding of compressible hydraulic power flow, the ideal relationships of pumps and motors with compressible fluid are then derived. These differ from incompressible formulae by replacing p by Φ and identifying an appropriate displacement. From these, definitions for mechanical efficiency, volumetric efficiency, and power efficiency are obtained. Unlike the previous attempts, these definitions are mutually consistent in that the product of mechanical and volumetric efficiencies is indeed the power efficiency. Furthermore, they are exact and are suitable even if the bulk modulus is pressure dependent.

To gain insights into these new efficiency definitions, various modes of non-ideal effects in a piston pump/motor with variable valve timing are modeled and their effects on the mechanical, volumetric and power efficiencies are obtained. These non-ideal effects include piston-bore friction, leakage, valve throttling, and non-ideal valve timing.
Analog implementation of a Hodgkin–Huxley model neuron
Authors: Rutherford George H. , Mobille Zach D. , Brandt-Trainer Jordan , Follmann Rosangela , Rosa Epaminondas
Published: October 2020

We construct an electronic circuit for mimicking a single neuron's behavior in connection with the dynamics of the Hodgkin–Huxley mathematical model. Our results show that the electronic neuron, even though it contains binary-state circuitry components, displays a timing interplay between the ion channels, which is consistent with the corresponding timing encountered in the model equations. This is at the core of the mechanism determining not only the creation of action potentials but also the neuronal firing rate output. This work is suitable for educational purposes in physics, mathematical modeling, electronics, and neurophysiology and can be extended for implementation in networked neurons for more advanced studies of neuronal behaviors.
Exploring delay dynamics with a programmable electronic delay
circuit
Authors: Perez Edgar , Werkheiser Colleen , Striff Alex , Illing Lucas
Published: October 2020

Delay dynamics occur in a wide variety of natural and man-made systems. Even simple delay systems can generate complex dynamics whose exploration is rewarding. To allow such exploration as part of advanced undergraduate laboratory courses and be able to utilize systems that operate at convenient timescales, it is necessary to delay analog signals by several milliseconds. In this paper, we describe an implementation of a programmable digital circuit capable of delaying DC-coupled analog signals up to 262 ms at a 1 MHz sampling rate. The initial history of the system may also be arbitrarily programmed, enabling the study of transient behavior. As an application, we discuss the use of this programmable delay in a feedback circuit that produces period-four triangular solutions, in complete agreement with theoretical predictions.
A completely algebraic solution of the simple harmonic oscillator
Authors: Rushka M. , Freericks J. K.
Published: October 2020

We present a full algebraic derivation of the wavefunctions of a simple harmonic oscillator. This derivation illustrates the abstract approach to the simple harmonic oscillator by completing the derivation of the coordinate-space or momentum-space wavefunctions from the energy eigenvectors. It is simple to incorporate into the undergraduate and graduate curricula. We provide a summary of the history of operator-based methods as they are applied to the simple harmonic oscillator. We present the derivation of the energy eigenvectors along the lines of the standard approach that was first presented by Dirac in 1947 (and is modified slightly here in the spirit of the Schrödinger factorization method). We supplement it by employing the appropriate translation operator to determine the coordinate-space and momentum-space wavefunctions algebraically, without any derivatives.
Integrated proteomics reveals brain-based cerebrospinal fluid biomarkers in asymptomatic and symptomatic Alzheimer’s disease
Authors: Higginbotham Lenora , Ping Lingyan , Dammer Eric B. , Duong Duc M. , Zhou Maotian , Gearing Marla , Hurst Cheyenne , Glass Jonathan D. , Factor Stewart A. , Johnson Erik C. B. , Hajjar Ihab , Lah James J. , Levey Allan I. , Seyfried Nicholas T.
Published: October 2020

Integrative proteomic analysis identifies CSF biomarker panels linked to brain-based pathophysiologies in Alzheimer’s disease.
The structural basis for Z α
1
-antitrypsin polymerization in the liver
Authors: Faull Sarah V. , Elliston Emma L. K. , Gooptu Bibek , Jagger Alistair M. , Aldobiyan Ibrahim , Redzej Adam , Badaoui Magd , Heyer-Chauhan Nina , Rashid S. Tamir , Reynolds Gary M. , Adams David H. , Miranda Elena , Orlova Elena V. , Irving James A. , Lomas David A.
Published: October 2020

α
1
-Antitrypsin polymers from human tissue have a structure most consistent with an intermolecular C-terminal domain swap.
Endogenous retroviruses drive KRAB zinc-finger protein family expression for tumor suppression
Authors: Ito Jumpei , Kimura Izumi , Soper Andrew , Coudray Alexandre , Koyanagi Yoshio , Nakaoka Hirofumi , Inoue Ituro , Turelli Priscilla , Trono Didier , Sato Kei
Published: October 2020

The derepression of HERVs in tumors leads to the up-regulation of hundreds of KZFPs, which are potential tumor suppressors.
Diamond microscope unlocks ancient rocks' magnetic secrets
Authors: Voosen Paul
Published: October 2020

Quantum sensor reveals clues about plate tectonics, planet formation, and climate change with exquisite resolution.
A rampage through the body
Authors: Wadman Meredith , Couzin-Frankel Jennifer , Kaiser Jocelyn , Matacic Catherine
Published: October 2020

The lungs are ground zero, but COVID-19 also tears through organ systems from brain to blood vessels.
Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances
Authors: van Klink Roel , Bowler Diana E. , Gongalsky Konstantin B. , Swengel Ann B. , Gentile Alessandro , Chase Jonathan M.
Published: October 2020

Local drivers of decline matter

Recent studies have reported alarming declines in insect populations, but questions persist about the breadth and pattern of such declines. van Klink
et al.
compiled data from 166 long-term surveys across 1676 globally distributed sites and confirmed declines in terrestrial insects, albeit at lower rates than some other studies have reported (see the Perspective by Dornelas and Daskalova). However, they found that freshwater insect populations have increased overall, perhaps owing to clean water efforts and climate change. Patterns of variation suggest that local-scale drivers are likely responsible for many changes in population trends, providing hope for directed conservation actions.

Science
, this issue p.
417
; see also p.
368
Structural basis of ER-associated protein degradation mediated by the Hrd1 ubiquitin ligase complex
Authors: Wu Xudong , Siggel Marc , Ovchinnikov Sergey , Mi Wei , Svetlov Vladimir , Nudler Evgeny , Liao Maofu , Hummer Gerhard , Rapoport Tom A.
Published: October 2020

A close-up view of the retrotranslocon

Misfolded endoplasmic reticulum (ER) proteins are retrotranslocated into the cytosol, polyubiquitinated, and degraded by the proteasome in a process known as ER-associated protein degradation (ERAD). ERAD of misfolded luminal ER proteins (ERAD-L) is mediated by the Hrd1 complex, composed of the ubiquitin ligase Hrd1 and four additional proteins (Hrd3, Der1, Usa1, and Yos9). Wu
et al.
report a cryo–electron microscopy structure of the active Hrd1 complex from yeast and, based on this structure, developed a model for how substrates are recognized and retrotranslocated. They propose that Hrd3 and Yos9 jointly create a luminal binding site for misfolded glycoproteins. Hrd1 and Der1 form “half-channels” juxtaposed in a thinned section of the ER membrane, which allows a polypeptide loop of an ERAD-L substrate to move through it.

Science
, this issue p.
eaaz2449
Structural basis for transcriptional start site control of HIV-1 RNA fate
Authors: Brown Joshua D. , Kharytonchyk Siarhei , Chaudry Issac , Iyer Aishwarya S. , Carter Hannah , Becker Ghazal , Desai Yash , Glang Lindsay , Choi Seung H. , Singh Karndeep , Lopresti Michael W. , Orellana Matthew , Rodriguez Tatiana , Oboh Ubiomo , Hijji Jana , Ghinger Frances Grace , Stewart Kailan , Francis Dillion , Edwards Bryce , Chen Patrick , Case David A. , Telesnitsky Alice , Summers Michael F.
Published: October 2020

One guanosine determines transcript fate

Transcripts of the HIV-1 RNA genome can be either spliced and translated into viral proteins or packaged into new virions as a progeny genome. The path taken depends on whether the transcript contains one guanosine at the 5′ terminus (1G) rather than two or three (2G or 3G). Brown
et al.
used nuclear magnetic resonance spectroscopy to show that 1G transcripts adopt a dimeric structure that sequesters a terminal cap required for translation and splicing but exposes sites that bind to the HIV-1 Gag protein, which recruits the genome during viral assembly. Conversely, 2G or 3G transcripts have the cap accessible, but Gag-binding sites are sequestered. Therefore, a single guanosine acts as a conformational switch to determine the fate of HIV-1 transcripts.

Science
, this issue p.
413
Next-generation epigenetic inhibitors
Authors: Filippakopoulos Panagis , Knapp Stefan
Published: October 2020

Selective bromodomain inhibitors provide new opportunities to modulate transcription
Down-regulation of Beclin1 promotes direct cardiac reprogramming
Authors: Wang Li , Ma Hong , Huang Peisen , Xie Yifang , Near David , Wang Haofei , Xu Jun , Yang Yuchen , Xu Yangxi , Garbutt Tiffany , Zhou Yang , Liu Ziqing , Yin Chaoying , Bressan Michael , Taylor Joan M. , Liu Jiandong , Qian Li
Published: October 2020

Beclin1 suppresses induced cardiomyocyte reprogramming through an autophagy-independent, Wnt signaling–dependent pathway.
Role of OB-Fold Protein YdeI in Stress Response and Virulence of Salmonella enterica Serovar Enteritidis
Authors: Arunima Aryashree , Swain Sunil Kumar , Patra Saumya Darshana , Das Susmita , Mohakud Nirmal Kumar , Misra Namrata , Suar Mrutyunjay
Published: October 2020

S
. Enteritidis during its life cycle encounters diverse stress factors inside the host. These intracellular conditions allow activation of specialized secretion systems to cause infection. We report a conserved membrane protein, YdeI, and elucidate its role in protection against various intracellular stress conditions. A key aspect of the study of a pathogen’s stress response mechanism is its clinical relevance during host-pathogen interaction. Bacterial adaptation to stress plays a vital role in evolution of a pathogen’s resistance to therapeutic agents. Therefore, investigation of the role of YdeI is vital for understanding the molecular basis of regulation of
Salmonella
pathogenesis. In conclusion, our findings may contribute to finding potential targets to develop new intervention strategies for treatment and prevention of enteric diseases.
Draft Whole-Genome Sequence of the Anthracene-Degrading Strain Mycolicibacterium frederiksbergense LB501T, Isolated from a Polycyclic Aromatic Hydrocarbon-Contaminated Soil
Authors: Augelletti Floriana , Tremblay Julien , Agathos Spiros N. , Jousset Alexandre , Stenuit Ben
Published: October 2020

Here, we report the draft whole-genome sequence of an anthracene-degrading bacterium,
Mycolicibacterium frederiksbergense
strain LB501T, using the PacBio and Illumina sequencing platforms. The complete genome sequence of strain LB501T consists of 6,713,618 bp and provides new insights into its metabolic capabilities, including aromatic conversion pathways with promiscuous activities.
Complete Coding Sequence of a Lumpy Skin Disease Virus from an Outbreak in Bulgaria in 2016
Authors: Mathijs Elisabeth , Vandenbussche Frank , Ivanova Emiliya , Haegeman Andy , Aerts Laetitia , De Leeuw Ilse , Van Borm Steven , De Clercq Kris
Published: October 2020

Lumpy skin disease (LSD) is an emerging cattle disease with serious economic consequences. We report the complete coding sequence of LSD virus 210LSD-249/BUL/16, detected in a blood sample from a diseased cow during an outbreak in Bulgaria (Kabile Village, Yambol Region) in June 2016.
Sex differences in circulating leptin as a marker of adiposity in obese or overweight adolescents with type 1 diabetes
Authors: Redondo Maria J , Siller Alejandro F , Gu Xiangjun , Tosur Mustafa , Bondy Melissa , Devaraj Sridevi , Sisley Stephanie
Published: October 2020

Introduction

We aimed to test whether the serum adipokines leptin and adiponectin are more strongly associated with body fat percentage (BF%) than body mass index (BMI) in adolescents with type 1 diabetes (T1D) and overweight/obesity.

Research design and methods

We studied all participants in the T1D Exchange Metformin Study (n=122, median age 12.9 years, range 12–19.5; 32% males; 77% non-Hispanic whites, 100% overweight or obesity; median diabetes duration 6.7 years, range 1.4–15) with a baseline serum sample where we measured leptin and adiponectin concentrations. Anthropometric, clinical, laboratory and dual-energy X-ray absorptiometry (DEXA) scan measurements were analyzed. We compared correlation coefficients between variables of interest.

Results

BF% by DEXA was significantly correlated with BMI Z-score (r=0.38, p<0.0001), BMI per cent of the 95th percentile (BMI%95) (r=0.45, p<0.0001), waist circumference (r=0.46, p<0.0001), leptin (r=0.58, p<0.00001) and leptin/adiponectin ratio (r=0.36, p<0.0001), while it was not significantly correlated with absolute body weight, adiponectin or insulin dose (total or basal). BF% was significantly more strongly correlated with leptin than with BMI Z-score in the overall group (p=0.022). However, there were sex-based differences. Among the significant correlations in the overall group, BF% was most strongly associated with leptin (r=0.75) in boys (n=39) but with waist circumference (r=0.58) in girls (n=83) (all p<0.0001).

Conclusions

Serum leptin could be used as a surrogate convenient marker of adiposity in overweight/obese adolescent boys with T1D, equivalent to BMI Z-score or BMI%95. In girls, waist circumference was the best performing marker overall, and was also strongly correlated with %BF in boys.
Not just money: what mothers value in conditional cash transfer programs in India
Authors: Rao Krishna D , Kachwaha Shivani , Kaplan Avril , Bishai David
Published: October 2020

Introduction

Conditional cash transfers (CCTs) have become an important policy tool for increasing demand for key maternal and child health services in low/middle-income countries. Yet, these programs have had variable success in increasing service use. Understanding beneficiary preferences for design features of CCTs can increase program effectiveness.

Methods

We conducted a Discrete choice experiment in two districts of Uttar Pradesh, India in 2018 with 405 mothers with young children (<3 years). Respondents were asked to choose between hypothetical CCT programme profiles described in terms of five attribute levels (cash, antenatal care visits, growth-monitoring and immunisation visits, visit duration and health benefit received) and responses were analysed using mixed logit regression.

Results

Mothers most valued the cash transfer amount, followed by the health benefit received from services. Mothers did not have a strong preference for conditionalities related to the number of health centre visits or for time spent seeking care; however, service delivery points were in close proximity to households. Mothers were willing to accept lower cash rewards for better perceived health benefits—they were willing to accept 2854 Indian rupees ($41) less for a programme that produced good health, which is about half the amount currently offered by India’s Maternal Benefits Program. Mothers who had low utilisation of health services, and those from poor households, valued the cash transfer and the health benefit significantly more than others.

Conclusion

Both cash transfers and the perceived health benefit from services are highly valued, particularly by infrequent service users. In CCTs, this highlights the importance of communicating value of services to beneficiaries by informing about health benefits of services and providing quality care. Conditionalities requiring frequent health centre visits or time taken for seeking care may not have large negative effects on CCT participation in contexts of good service coverage.
Expanding access to non-communicable disease care in rural Malawi: outcomes from a retrospective cohort in an integrated NCD–HIV model
Authors: Wroe Emily B , Kalanga Noel , Dunbar Elizabeth L , Nazimera Lawrence , Price Natalie F , Shah Adarsh , Dullie Luckson , Mailosi Bright , Gonani Grant , Ndarama Enoch P L , Talama George C , Bukhman Gene , Kerr Lila , Connolly Emilia , Kachimanga Chiyembekezo
Published: October 2020

Objectives

Non-communicable diseases (NCDs) account for one-third of disability-adjusted life years in Malawi, and access to care is exceptionally limited. Integrated services with HIV are widely recommended, but few examples exist globally. We report descriptive outcomes from an Integrated Chronic Care Clinic (IC3).

Design

This is a retrospective cohort study.

Setting

The study includes an HIV–NCD clinic across 14 primary care facilities in the rural district of Neno, Malawi.

Participants

All new patients, including 6233 HIV–NCD diagnoses, enrolled between January 2015 and December 2017 were included. This included 3334 patients with HIV (59.7% women) and 2990 patients with NCD (67.3% women), 10% overall under age 15 years.

Interventions

Patients were seen at their nearest health centre, with a hospital team visiting routinely to reinforce staffing. Data were collected on paper forms and entered into an electronic medical record.

Primary and secondary outcome measures

Routine clinical measurements are reported at 1-year post-enrolment for patients with more than one visit. One-year retention is reported by diagnosis.

Results

NCD diagnoses were 1693 hypertension, 668 asthma, 486 epilepsy, 149 diabetes and 109 severe mental illness. By December 2018, 8.3% of patients with NCD over 15 years were also on HIV treatment. One-year retention was 85% for HIV and 72% for NCDs, with default in 8.4% and 25.5% and deaths in 4.0% and 1.4%, respectively. Clinical outcomes showed statistically significant improvement for hypertension, diabetes, asthma and epilepsy. Of the 1807 (80%) of patients with HIV with viral load results, 85% had undetectable viral load.

Conclusions

The IC3 model, built on an HIV platform, facilitated rapid decentralisation and access to NCD services in rural Malawi. Clinical outcomes and retention in care are favourable, suggesting that integration of chronic disease care at the primary care level poses a way forward for the large dual burden of HIV and chronic NCDs.
Living with a left ventricular assist device: psychological burden and coping: protocol for a cross-sectional and longitudinal qualitative study
Authors: Levelink Michael , Eichstaedt Harald Christian , Meyer Sven , Brütt Anna Levke
Published: October 2020

Introduction

Due to technological progress and persistent shortage of donor hearts, left ventricular assist devices (LVADs) have become established in the treatment of advanced heart failure. Accordingly, more patients live with LVADs for prolonged periods. Related research focused primarily on clinical issues and little is known about psychosocial aspects of living with an LVAD. This study aims to explore psychological burden and coping following LVAD implantation.

Methods and analysis

An exploratory qualitative study with cross-sectional and longitudinal elements will be carried out. At least 18 patients with LVAD who have the device implanted from a few weeks to more than 3 years will be interviewed in the cross-sectional component using an interview guide. A subsample of patients who live with the LVAD for up to 3 months when recruited will be interviewed two additional times in the following year. The cross-sectional interviews will be analysed using an inductive qualitative content analysis to describe psychological burden, coping resources and behaviour from the patient’s perspective. Based on the findings, the longitudinal interviews will be analysed with a deductive content analysis to explore psychological adjustment during the first year after implantation. The findings will provide a deeper understanding of the complex and specific situation of patients with LVAD and of psychological adjustment to living with a life-sustaining implant. This can help clinicians in considering individual aspects to promote patient outcomes and is the basis for further research on healthcare interventions or technical solutions to reduce burden and for developing rehabilitation measures to promote psychosocial outcomes.

Ethics and dissemination

Ethical approval was obtained from the ethics committee of the School of Medicine and Health Sciences at the University of Oldenburg (2019-023). Study findings will be disseminated at national and international conferences and through peer-reviewed journals.

Trial registration number

German Clinical Trials Register (DRKS00016883).
Patients’ perceptions of safety in emergency medical services: an interview study
Authors: Venesoja Anu , Castrén Maaret , Tella Susanna , Lindström Veronica
Published: October 2020

Background

Research on patient safety in emergency medical services (EMS) has mainly focused on the organisation’s and/or the EMS personnel’s perspective. Little is known about how patients perceive safety in EMS. This study aims to describe the patients’ experiences of their sense of safety in EMS.

Methods

A qualitative design with individual interviews of EMS patients (n=21) and an inductive qualitative content analysis were used.

Results

Patients’ experiences of EMS personnel’s ability or inability to show or use their medical, technical and driving skills affected the patients’ sense of safety. When they perceived a lack of professionalism and knowledge among EMS personnel, they felt unsafe. Patients highlighted equality in the encounter, the quality of the information given by EMS personnel and the opportunity to participate in their care as important factors creating a sense of safety during the EMS encounter. Altogether, patients’ perceptions of safety in EMS were connected to their confidence in the EMS personnel.

Conclusions

Overall, patients felt safe during their EMS encounter, but the EMS personnel’s professional competence alone is not enough for them to feel safe. Lack of communication or professionalism may compromise their sense of safety. Further work is needed to explore how patients’ perceptions of safety can be used in improving safety in EMS.
Effect of concussion on salary and employment: a population-based event time study using a quasi-experimental design
Authors: Fallesen Peter , Campos Benito
Published: October 2020

Objective

Concussions are the most frequent traumatic brain injuries. Yet, the socioeconomic impact of concussions remains unclear. Socioeconomic effects of concussions on working-age adults were studied on a population scale.

Design

This population-based, event time study uses administrative data as well as hospital and emergency room records for the population of Denmark.

Setting

We study all Danish patients, aged 20–59 years, who were treated at a public hospital or at an emergency room between 2003 and 2017 after suffering a concussion without other intracranial or extracranial injuries (n=55 424 unique individuals). None of the patients had a prior diagnosis of intracranial or extracranial injuries within the past 10 years leading up to the incident.

Primary and secondary outcome measures

As primary endpoint, we investigate the mean effect of concussion on annual salaried income within a 5-year period after trauma. In an exploratory analysis, we study whether the potential impact of concussion on annual salaried income is driven by patient age, education or economic cycle.

Results

Concussion was associated with an average change in annual salary income of −€1223 (95% CI: −€1540 to −905, p<0.001) corresponding to a salary change of −4.2% (95% CI: −5.2% to −3.1 %). People between 30 and 39 years and those without high school degrees suffered the largest salary decreases. Affected individuals leaving the workforce drove the main part of the decrease. Absolute annual effect sizes were countercyclical to the unemployment rate.

Conclusions

Concussions have a large and long-lasting impact on salary and employment of working-age adults on a nationwide scale.
Valuation study for a preference-based quality of life measure for dental caries (Dental Caries Utility Index - DCUI) among Australian adolescents - study protocol
Authors: Hettiarachchi Ruvini , Kularatna Sanjeewa , Byrnes Joshua , Mulhern Brendan , Chen Gang , Scuffham Paul A
Published: October 2020

Introduction

A new health state classification system has been developed for dental caries - Dental Caries Utility Index (DCUI) to facilitate the assessment of oral health interventions in the cost-utility analysis (CUA). This paper reports the protocol for a valuation study, which aims to generate a preference-based algorithm for the classification system for the DCUI.

Methods and analysis

Discrete choice experiments (DCEs) will be conducted to value health states generated by the DCUI classification system and preferences for these health states will be modelled to develop a utility algorithm. DCEs produce utility values on a latent scale and these values will be anchored into the full health-dead scale to calculate the quality-adjusted life years in CUA. There is no previous evidence for the most suitable anchoring method for dental caries health state valuation. Hence, we will first conduct pilot studies with two anchoring approaches; DCE including duration attribute and DCE anchoring to worst heath state in Visual Analogue Scale. Based on the pilot studies, the most suitable anchoring method among two approaches will be used in the main valuation survey, which will be conducted as an online survey among a representative sample of 2000 adults from the Australian general population. Participants will be asked to complete a set of DCE choice tasks along with anchoring tasks, basic social-demographic questions, DCUI, a generic preference-based measure and oral health quality of life instrument.

Ethics and dissemination

Ethical approval for this study was obtained from the Human Research Ethics Committee, Griffith University (reference number HREC/2019/550). The generated algorithm will facilitate the use of the new dental caries preference-based measure in economic evaluations of oral health interventions. The results will be disseminated through journal articles and professional conferences.
Cross-sectional analysis of bibliometrics and altmetrics: comparing the impact of qualitative and quantitative articles in the British Medical Journal
Authors: Retrouvey Helene , Webster Fiona , Zhong Toni , Gagliardi Anna R , Baxter Nancy N
Published: October 2020

Objectives

In comparison to quantitative research, the impact of qualitative articles in the medical literature has been questioned by the BMJ; to explore this, we compared the impact of quantitative and qualitative articles published in BMJ.

Design

Cross-sectional survey.

Setting

Articles published in the BMJ between 2007 and 2017.

Main outcome measures

Bibliometric and altmetric measures of research impact were collected using Web of Science, Google Scholar, Scopus, Plum Analytics and ProQuest Altmetric. Bibliometric measures consisted of citation numbers, field weighted citation impact and citation percentile. Altmetric measures consisted of article usage, captures, mentions, readers, altmetric attention score and score percentile. Scores were compared using the Wilcoxon Rank-sum test.

Results

We screened a total of 7777 articles and identified 42 qualitative articles. Each qualitative article was matched to 3 quantitative articles published during the same year (126 quantitative articles). Citation numbers were not statistically different between the two research types; the median number of citations (google scholar) per quantitative article was 62 (IQR 38–111) versus 58 (IQR 36–85) per qualitative article (p=0.47). Using Plum Analytics, qualitative articles were found to have a significantly higher usage, with a median of 984 (IQR 581–1351) versus 379 (IQR 177–763) for quantitative (p<0.001). The Altmetric Attention Score was higher for quantitative articles at 16 (IQR 7–37) versus qualitative articles at 9 (IQR 5–23, p=0.05), as was the Altmetric Score percentile 93 (IQR 87–96) versus 88 (IQR 76–95; p=0.02).

Conclusion

Qualitative and quantitative articles published in the BMJ between 2007 and 2017 both have a high impact. No article type was consistently superior in terms of bibliometric or altmetric measures, suggesting that type of article is not the major driver of impact.
Faecal immunochemical test is superior to symptoms in predicting pathology in patients with suspected colorectal cancer symptoms referred on a 2WW pathway: a diagnostic accuracy study
Authors: D'Souza Nigel , Georgiou Delisle Theo , Chen Michelle , Benton Sally , Abulafi Muti
Published: October 2020

Objective

To assess whether a faecal immunochemical test (FIT) could be used to select patients with suspected colorectal cancer (CRC) symptoms for urgent investigation.

Design

Multicentre, double-blinded diagnostic accuracy study in 50 National Health Service (NHS) hospitals across England between October 2017 and December 2019. Patients referred to secondary care with suspected CRC symptoms meeting NHS England criteria for urgent 2 weeks wait referral and triaged to investigation with colonoscopy were invited to perform a quantitative FIT. The sensitivity of FIT for CRC, and effect of relevant variables on its diagnostic accuracy was assessed.

Results

9822 patients were included in the final analysis. The prevalence of CRC at colonoscopy was 3.3%. The FIT positivity decreased from 37.2% to 19.0% and 7.6%, respectively, at cut-offs of 2, 10 and 150 µg haemoglobin/g faeces (µg/g). The positive predictive values of FIT for CRC at these cut-offs were 8.7% (95% CI, 7.8% to 9.7%), 16.1% (95% CI 14.4% to 17.8%) and 31.1% (95% CI 27.8% to 34.6%), respectively, and the negative predictive values were 99.8% (95% CI 99.7% to 99.9%), 99.6% (95% CI 99.5% to 99.7%) and 98.9% (95% CI 98.7% to 99.1%), respectively. The sensitivity of FIT for CRC decreased at the same cut-offs from 97.0% (95% CI 94.5% to 98.5%) to 90.9% (95% CI 87.2% to 93.8%) and 70.8% (95% CI 65.6% to 75.7%), respectively, while the specificity increased from 64.9% (95% CI 63.9% to 65.8%) to 83.5% (95% CI 82.8% to 84.3%) and 94.6% (95% CI 94.1% to 95.0%), respectively. The area under the receiver operating characteristic curve was 0.93 (95% CI 0.92 to 0.95).

Conclusion

FIT sensitivity is maximised to 97.0% at the lowest cut-off (2 µg/g); a negative FIT result at this cut-off can effectively rule out CRC and a positive FIT result is better than symptoms to select patients for urgent investigations.

Trial registration number

ISRCTN49676259.
D-dimer blood concentrations to exclude left atrial thrombus in patients with atrial fibrillation
Authors: Almorad Alexandre , Ohanyan Anush , Pintea Bentea Georgiana , Wielandts Jean-yves , El Haddad Milad , Lycke Michelle , O’Neill Louisa , Morissens Marielle , De Keyzer Eva , Nguyen Thomas , Anghel Laura , Samyn Sophie , Berdaoui Brahim , Tavernier Rene , Vandekerckhove Yves , Duytschaever Mattias , Verbeet Thierry , Knecht Sebastien , Castro Rodriguez José
Published: October 2020

Objective

Left atrial (LA) thrombus is routinely excluded by transoesophageal echocardiography (TOE) before cardioversion for non-valvular atrial fibrillation (AF). In the D-dimer blood concentrations to exclude LA thrombus in patients with AF study, two D-dimer cut-offs were compared to exclude LA thrombus prior to cardioversion. One was fixed to 500 ng/mL (DD500), based on clinical practice where such values are commonly accepted to exclude a thrombus. The other cut-off was adjusted to 10 times the patient’s age (DDAge), based on the cut-off used to exclude pulmonary embolism.

Methods

142 consecutive patients with non-valvular AF aged 69.7±11.4 years (52% with paroxysmal AF) referred for precardioversion TOE to exclude LA thrombus were prospectively enrolled. D-dimers were measured at the time of TOE by an ELISA test.

Results

LA thrombus was excluded with TOE in 129 (91%) and confirmed in 13 (9%) patients. D-dimers were significantly lower in patients without LA thrombus (729±611 vs 2376±1081 ng/L; p<0.05). DDAge indicated absence of LA thrombus with higher specificity than DD500 (66.4% vs 50.4%; p<0.05). Both cut-offs were able to identify all 13 patients with LA thrombus (false negative 0%). Patients with D-dimers <DDAge and without LA thrombus (true negative) represented 60.6% of the population and could have safely avoided TOE (flow chart).

Conclusions

This study demonstrates the efficacy of D-dimer cut-offs to exclude LA thrombus in patients with AF. Age adjustment greatly increases the proportion of patients in whom LA thrombus can be safely excluded and consequently avoid precardioversion TOE.
Mental health impairment triggered by the COVID-19 pandemic in a sample population of German students
Authors: Schlichtiger Jenny , Brunner Stefan , Steffen Julius , Huber Bruno C
Published: October 2020

Due to the rapid spread of the COVID-19 pandemic, a lockdown including limitation of activity and restrictions of non-essential travel was imposed on March 21, 2020 in the State of Bavaria, Germany. The implementation of activity restrictions not only strongly affects the economy but will possibly also impact the mental and physical health status of the general population. Therefore, the present study aimed to explore psychological effects of the COVID-19 crisis on a sample of Bavarian students. In this cross-sectional study, we enrolled 1943 voluntary subjects from Bavarian universities. All subjects completed an online questionnaire asking for mental health stress, as well as potential factors, influencing the state of mental stress during pandemic lockdown. In our study cohort, 17.3% (n=336) of the students indicated that they experienced less mental stress through COVID-19 pandemic, while 39.6% (n=770) stated that they had an increased psychological burden. The bivariate analysis identified sex and the level of physical activity as potential risk factors for the level of mental stress during the COVID-19 pandemic. Further research is necessary to investigate specific symptoms of mental stress and the overall long-term impact on mental health.