bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a Multi-Cable-Driven Continuum Robot Controlled by Parallel Platforms
Authors: Chen Xinbo , Yao Jiantao , Li Tong , Li Haili , Zhou Pan , Xu Yundou , Zhao Yongsheng 
Published: October 2020

Abstract
Cable-driven continuum robots exhibit excellent capabilities in the unstructured environment due to their inherent compliance and dexterity. To improve the reliability and load capacity of continuum robots, increasing the number of cables is often used in the control of continuum robots. However, the number of actuators will increase with the cables. To tackle this challenge, this work proposes a method for increasing the number of cables without increasing actuators in a continuum robot through parallel platforms. The parallel platforms are used to control all the cables in the continuum robot and can be separated from the continuum robot to enable the remote drive of a manipulation arm by using the cable-tube structure. The manipulation arm is composed of several independent bending modules in series, which can be configured freely according to the demand of degrees-of-freedom. Further, each bending module is controlled independently by a parallel platform, which can avoid the mutual interference between the cables of one bending module and another one, improve the position accuracy and simplify the control difficulty of the manipulation arm. To evaluate the proposed method, this work develops a prototype of six-cable-driven continuum robot controlled by 3RPS parallel platforms and presents some basic kinematic models to describe its function, and then an experimental work characterizing its performance. Experimental results illustrated the importance of increasing the number of cables, the rationality of kinematic models of the continuum robot, and the feasibility of controlling multiple cables by a parallel platform.
Analysis of Burnett Stresses and Entropy Generation for Pressure-Driven Plane Poiseuille Flow
Authors: Yadav Upendra , Agrawal Amit 
Published: October 2020

Abstract
In this paper, we undertake an analytical study of stresses (augmented and Onsager–Burnett) and entropy generation for the plane Poiseuille flow problem, and their variation with Knudsen number. The gas flow is assumed to be 2D laminar, fully developed, compressible, and isothermal; these assumptions make the problem amenable to analytical treatment. The variation of stresses and entropy generation has been analyzed over a large range of Knudsen number. The magnitude of stresses and entropy generation at a particular position in the channel has been considered. It is found that the augmented and OBurnett normal stresses are of opposite signs to the corresponding Navier–Stokes stresses, while the magnitude of the net normal stress increases with Knudsen number. The magnitude of the augmented Burnett shear stress is insignificant as compared to the augmented Burnett normal stresses. A close match between the augmented and OBurnett normal stresses has been found at low Knudsen number. However, an opposite variation has been observed between the augmented and Onsager shear stresses at high Knudsen number. A good comparison of the normalized mass flow rate with the reported value in the literature helps to validate our analysis. A minimum in the variation of normalized entropy generation against the Knudsen number (Kn) is observed at Kn close to unity, and is being reported for the first time. The magnitude of net entropy generation from the summation of Navier–Stokes and augmented Burnett stresses is found to be positive, even in the transition regime of gas flow. Further, an appearance of minimum or maximum in normalized net shear stress versus Knudsen number, depending upon the lateral position in the microchannel, has also been observed. Altogether, this analysis supports the validity of the Navier–Stokes equation with modified constitutive expression, even for higher Knudsen numbers. Moreover, the significant terms of Burnett stress are pointed out by the analysis, which can help in developing reduced-order model for these equations.
Experimental and Numerical Analysis of Gas Premix Turbulent Flames Stabilized in a Swirl Burner With Central Bluff Body
Authors: Biagioli Fernando , Innocenti Alessandro , Terhaar Steffen , Marchione Teresa 
Published: October 2020

Abstract
Lean premixed gas turbulent flames stabilized in the flow generated by an industrial swirl burner with a central bluff body are experimentally found to behave bistable. This bistable behavior, which can be triggered via a small change in some of the controlling parameters, for example, the bulk equivalence ratio, consists in a rather sudden transition of the flame from completely lifted to well attached to the bluff body. This has impact on combustion dynamics, emissions, and pressure losses. While several experimental investigations exist on this topic, numerical analysis is limited. This work is therefore also of numerical nature, with a twofold scope: (a) simulation and validation with experiments of the bistable flame behavior via computational fluid dynamics (CFD) in the form of large eddy simulation (LES) and (b) analysis of CFD results to shed light on the flame stabilization properties. LES results, in case of the lifted flame, show that the vortex core is sharply precessing at a given frequency. Phase averaging these results at the frequency of precession clearly indicates a counterintuitive and unexpected presence of reverse flow going all the way through the flame apex and the bluff body tip. The counterintuitive presence of a lifted flame is explained here in terms of the phase averaged data, which show that the flame apex is not placed at the center of the spinning reverse flow region. It is instead slightly shifted radially outward where the axial velocity recovers to low positive values of the order of the turbulent burning rate. A simple one-dimensional flame stabilization model is applied to explain this peculiar flame behavior. This model provides first an estimation of the flame radius of curvature in terms of axial velocity and turbulence quantities. This radius is therefore used to determine the total flux of reactants into the flame, given by an axial convection and radial diffusion contributions. Subsequently, the possibility of the flame positioned at the center of the vortex is excluded based on the balance between this flux and the turbulent burning rate. A clear explanation of the mechanism leading to the sudden flame jump has instead not been identified and only some hypotheses are provided.
Aero Engine Concepts Beyond 2030: Part 1—The Steam Injecting and Recovering Aero Engine
Authors: Schmitz Oliver , Klingels Hermann , Kufner Petra 
Published: October 2020

Abstract
Recognizing the attention currently devoted to the environmental impact of aviation, this three-part publication series introduces two new aircraft propulsion concepts for the timeframe beyond 2030. This first part focuses on the steam injecting and recovering aero engine (SIRA) concept. Exhaust heat generated steam is injected into the combustion chamber. By use of a condenser, installed behind the steam generator, the water is recovered from the exhaust gas–steam mixture. Both lead to a noticeable increase in specific power compared to a conventional gas turbine and, foremost, to a significant increase in thermodynamic efficiency. The proposed concept is expected to reduce fuel burn and carbon dioxide (CO2) emissions by about 15% and nitrogen oxides (NOx) formation can be almost completely avoided compared to state-of-the-art engines of the same technology level. Moreover, the described concept has the potential to drastically reduce or even avoid the formation of condensation trails. Thus, the SIRA concept operated with sustainable aviation fuels offers the potential for climate-neutral aviation. Based on consistent thermodynamic descriptions, preliminary designs and initial performance studies, the potentials of the concepts are analyzed. Complementarily, a detailed discussion on concrete engineering solutions considers the implementation into aircraft. Finally, the impact on emissions is outlined.
Reliability of Change-of-Direction Economy in Soccer Players
Authors: Dolci Filippo , Kilding Andrew E. , Spiteri Tania , Chivers Paola , Piggott Ben , Maiorana Andrew , Hart Nicolas H. 
Published: October 2020

Purpose: To evaluate the reliability of new change-of-direction-economy tests (assessing energetic efficiency when performing continuous shuttle runs) compared with common running-economy tests in soccer players Methods: Sixteen subelite, male soccer players were recruited to perform a testing battery involving running economy (RE), 10-m shuttle-running economy (SRE10), and 20-m shuttle-running economy (SRE20) at 8.4 km·h−1 mean speed on 2 different days within 48 hours. SRE10 and SRE20 consisted of continuous shuttle runs interspersed with 180° directional changes. During the RE, SRE20, and SRE10 tests, respiratory exchange ratio and oxygen uptake were collected and used to calculate the movement-economy values over any running condition as oxygen cost and energetic cost. The secondary variables (carbon dioxide production, heart rate, minute ventilation, and blood lactate) were also monitored during all tests. Results: Depending on expression (oxygen cost or energetic cost), reliability was established for RE (CV: 5.5%–5.8%; ICC = .77–.88), SRE10 (CV: 3.5%–3.8%; ICC = .78–.96), and SRE20 (CV: 3.5%–3.8%; ICC = .66–.94). All secondary physiological variables reported good reliability (CV < 10%), except for blood lactate (CV < 35.8). The RE, SRE10, and SRE20 tests show good reliability in soccer players, whereas blood lactate has the highest variability among physiological variables during the economy tests. Conclusion: The assessment of change-of-direction economy through performing 20- and 10-m shuttle runs is reliable and can be applied to evaluate soccer players’ energetic movement efficiency under more soccer-specific running conditions.
Is There a Decrease in the Acromiohumeral Distance Among Recreational Overhead Athletes With Rotator Cuff–Related Shoulder Pain?
Authors: de Oliveira Fábio Carlos Lucas , Ager Amanda L. , Roy Jean-Sébastien 
Published: October 2020

Context:Recreational overhead athletes are exposed to high overload, which increases the risk of shoulder injuries. Reduction of the acromiohumeral distance (AHD) is often associated with rotator cuff–related shoulder pain (RCRSP) among the general population. However, the AHD of symptomatic shoulders of recreational athletes has not yet been compared with their asymptomatic shoulders.Objective:To compare the AHD of a symptomatic to asymptomatic shoulder at rest (0°) and 60° abduction. To establish the relationship between AHD, pain, and functional limitations of recreational athletes with RCRSP.Design:Cross-sectional study.Setting:University laboratory.Participants:A total of 45 recreational overhead athletes with RCRSP were examined.Main Outcome Measures:The AHD was measured by ultrasonography at 0° and 60° abduction (angles). Shoulder pain was assessed using a numeric pain scale, whereas functional limitations were assessed using the The Disabilities of the Arm, Shoulder, and Hand questionnaire. Differences in the between-shoulders condition (symptomatic and asymptomatic) were determined using 2-way analysis of variance for repeated measures. A Pearson correlation established the relationship between AHD, pain, and functional limitations.Results:No angles × shoulder condition interactions (P = .776) nor shoulder condition effects (P = .087) were detected, suggesting no significant differences (P > .05) between asymptomatic and symptomatic shoulders in the AHD at 0° or 60°. The AHD at 60° reduced significantly compared with 0° (3.05 [1.36] mm [2.77–3.33], angle effects:P < .001). The AHD at 0° and 60° was not correlated with pain or functional limitations (−.205 ≤ r ≤ .210, .167 ≤ P ≤ .585).Conclusions:The AHD of recreational athletes is not decreased in symptomatic shoulders compared with asymptomatic shoulders. Reduction of the AHD in symptomatic shoulders is not associated with an increase in pain or functional limitations of recreational athletes with RCRSP.
A complex phenotype in salmon controlled by a simple change in migratory timing
Authors: Thompson Neil F. , Anderson Eric C. , Clemento Anthony J. , Campbell Matthew A. , Pearse Devon E. , Hearsey James W. , Kinziger Andrew P. , Garza John Carlos 
Published: October 2020

Unexpectedly simpleChinook salmon are known to return to spawn at two distinct times of the year: spring and fall. Individuals that return during these times have generally been referred to as parts of distinct groups, or ecotypes, with traits specific to their timing and presumed divergence being caused by the lack of interbreeding. By looking at genomes across fish from both runs, Thompsonet al.found that a single genomic region of interest was nearly perfectly associated with run timing but not with other traits such as maturity and fat reserves (see the Perspective by McKinney). Further, they conclude that the region operates as a Mendelian trait, with assortment dictating run timing and associated phenotypes being caused by the migration environment rather than genetics.Science, this issue p.609; see also p.526
Clumped isotope thermometry of modern and fossil snail shells from the Himalayan-Tibetan Plateau: Implications for paleoclimate and paleoelevation reconstructions
Authors: Wang Yang , Passey Benjamin , Roy Rupsa , Deng Tao , Jiang Shijun , Hannold Chance , Wang Xiaoming , Lochner Eric , Tripati Aradhna 
Published: October 2020

Abstract
Carbonate clumped isotope thermometry has been applied to fossil mollusk shells from Tibet to reconstruct the paleoclimate and paleoelevation of the region. However, inferred paleoelevation and climatic conditions from this proxy are inconsistent with paleontological evidence. Here, we report new clumped isotope data from both modern and fossil (5–4 Ma) freshwater mollusk shells with the results of X-ray diffraction (XRD) analyses of fossil shells from the Himalayan-Tibetan Plateau. Although all of the fossil shells analyzed in this study appeared pristine based on visual inspection, XRD data reveal that more than half of these apparently “pristine” fossil shells contain trace amounts of calcite. Clumped isotope temperatures derived from the fossil shells display a large range of variation (&gt;22 °C). Among the fossil shells analyzed, those containing traces of calcite have yielded temperatures that are on average ∼10 °C lower than those with no detectable calcite from the same strata. These observations suggest that clumped isotope alteration can occur in aragonite shells in low-temperature environments and even in shells with no visible signs of alteration that contain only traces of calcite. The temperatures derived from fossil shells with no detectable calcite are on average 4 °C higher than those derived from modern shells, indicating that southwest Tibet was warmer 4–5 Ma than today. After accounting for temperature change due to global cooling, the difference in clumped isotope temperatures between pristine fossil shells and modern shells suggests that the paleoelevation of the southwestern Tibetan Plateau in the Pliocene was similar to its present-day elevation.
Treatments and outcomes of untreated cerebral cavernous malformations in China: study protocol of a nationwide multicentre prospective cohort study
Authors: Lin Fuxin , He Qiu , Gao Zhuyu , Yu Lianghong , Wang Dengliang , Zheng Shufa , Lin Yuanxiang , Kang Dezhi 
Published: October 2020

IntroductionThe treatment decision and long-term outcomes of previously untreated cerebral cavernous malformation (U-CCM) are still controversial. Therefore, we are conducting a nationwide multicentre prospective registry study in China to determine the natural history and effect of surgical treatment on long-term outcomes in Chinese people with U-CCM.Methods and analysisThis study was started on 1 January 2018 and is currently ongoing. It is a cohort follow-up study across a 5-year period. Patients will be followed up for at least 3 years after inception. Patients with U-CCM will be enrolled from 24 Grade III, level A hospitals distributed all over China. The cohort size is estimated to be 1200 patients. Patients are registered in surgically treated group and conservatively treated group. Clinical characteristics, radiology information and laboratory data are prospectively collected using an electronic case report form through an electronic data capture system. The primary outcome of this study is poor clinical outcome at the last follow-up (modified Rankin Scale score >2 lasting at least 1 year). The secondary outcome includes symptomatic haemorrhage, drug refractory epilepsy, focal neurological deficits, morbidity and all-cause mortality during follow-up. Univariate and multivariate regression analysis will be performed to determine the risk factors for poor outcomes in all patients, and to estimate the effect of surgery. Life tables, Kaplan-Meier estimates, log-rank test and proportional hazards Cox regression will be used to analyse the follow-up data of conservatively treated patients to determine the natural history of U-CCM. Initial presentation and location of U-CCM are prespecified subgroup factors.Ethics and disseminationThe study protocol and informed consent form have been reviewed and approved by the Research Ethical Committee of First Affiliated Hospital of Fujian Medical University (FAHFMU-2018-003).Written informed consent will be obtained from each adult participant or from the guardian of each paediatric participant. The final results will be published in peer-reviewed journals.Trial registration numberNCT03467295.
Standard echocardiography versus handheld echocardiography for the detection of subclinical rheumatic heart disease: a systematic review and meta-analysis of diagnostic accuracy
Authors: Telford Lisa Helen , Abdullahi Leila Hussein , Ochodo Eleanor Atieno , Zuhlke Liesl Joanna , Engel Mark Emmanuel 
Published: October 2020

ObjectiveTo summarise the accuracy of handheld echocardiography (HAND) which, if shown to be sufficiently similar to that of standard echocardiography (STAND), could usher in a new age of rheumatic heart disease (RHD) screening in endemic areas.DesignSystematic review and meta-analysis.Data sourcesPubMed, Scopus, EBSCOHost and ISI Web of Science were initially searched on 27 September 2017 and again on 3 March 2020 for studies published from 2012 onwards.Eligibility criteriaStudies assessing the accuracy of HAND compared with STAND when performed by an experienced cardiologist in conjunction with the 2012 World Heart Federation criteria among populations of children and adolescents living in endemic areas were included.Data extraction and synthesisTwo reviewers independently extracted data and assessed the methodological quality of included studies against review-specific Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 criteria. A meta-analysis using the hierarchical summary receiver operating characteristic model was conducted to produce summary results of sensitivity and specificity. Forest plots and scatter plots in receiver operating characteristic space in combination with subgroup analyses were used to investigate heterogeneity. Publication bias was not investigated.ResultsSix studies (N=4208) were included in the analysis. For any RHD detection, the pooled results from six studies were as follows: sensitivity: 81.56% (95% CI 76.52% to 86.61%) and specificity: 89.75% (84.48% to 95.01%). Meta-analytical results from five of the six included studies were as follows: sensitivity: 91.06% (80.46% to 100%) and specificity: 91.96% (85.57% to 98.36%) for the detection of definite RHD only and sensitivity: 62.01% (31.80% to 92.22%) and specificity: 82.33% (65.15% to 99.52%) for the detection of borderline RHD only.ConclusionsHAND displayed good accuracy for detecting definite RHD only and modest accuracy for detecting any RHD but demonstrated poor accuracy for the detection of borderline RHD alone. Findings from this review provide some evidence for the potential of HAND to increase access to echocardiographic screening for RHD in resource-limited and remote settings; however, further research into feasibility and cost-effectiveness of wide-scale screening is still needed.PROSPERO registration numberCRD42016051261.
Association between medical students’ prior experiences and perceptions of formal online education developed in response to COVID-19: a cross-sectional study in China
Authors: Wang Cixiao , Xie A’na , Wang Weimin , Wu Hongbin 
Published: October 2020

Objectives(1) Understanding the characteristics of online learning experiences of Chinese undergraduate medical students; (2) Investigating students’ perceptions of ongoing online education developed in response to COVID-19 and (3) Exploring how prior online learning experiences are associated with students’ perceptions.DesignStudents’ familiarity with online learning modes and corresponding perceived usefulness (PU) according to their previous experiences were investigated using an online survey. The survey also collected data on students’ perceptions through their evaluation of and satisfaction with current online learning.SettingIn response to the educational challenges created by COVID-19, medical schools in China have adopted formal online courses for students.ParticipantsThe questionnaire was sent to 225 329 students, of whom 52.38% (118 080/225 329) replied, with valid data available for 44.18% (99 559/225 329).MethodsPearson correlations and t-tests were used to examine the relationship between familiarity and PU. Multiple linear regression and logistic regression analyses were used to determine the impact of prior learning experiences and its interactions with gender, area, learning phase and academic performance on students’ perceptions.ResultsStudents’ PU had a significant positive correlation with their familiarity with online learning modes (p<0.01). Students’ evaluation of and satisfaction with their current online education were positively associated with their familiarity (β=0.46, 95% CI 0.45 to 0.48, p<0.01; OR 1.14, 95% CI 1.13 to 1.14, p<0.01) with and PU (β=3.11, 95% CI 2.92 to 3.30, p<0.01; OR 2.55, 95% CI 2.37 to 2.75, p<0.01) of online learning. Moreover, the higher the students’ learning phases, the lower the associations between PU and students’ evaluation of and satisfaction with ongoing online education.ConclusionsMedical students in China have experiences with various online learning modes. Prior learning experiences are positively associated with students’ evaluation of and satisfaction with current online education. Higher learning phases, in which clinical practices are crucial, and high academic performance led to lower evaluation and satisfaction scores.