bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reverse Thrust Aerodynamics of Variable Pitch Fans
Authors: Williams Tim S. , Hall Cesare A. 
Published: March 2019

Abstract
Variable pitch fans are of interest for future low-pressure ratio fan systems since they provide improved operability relative to fixed pitch fans. If they can also be re-pitched such that they generate sufficient reverse thrust they could eliminate the engine drag and weight penalty associated with bypass duct thrust reversers. This paper sets out to understand the details of the 3D fan stage flow field in reverse thrust operation. This study uses the Advanced Ducted Propulsor variable pitch fan test case, which has a design fan pressure ratio of 1.29. Comparison with spanwise probe measurements show that the computational approach is valid for examining the variation of loss and work in the rotor in forward thrust. The method is then extended to a reverse thrust configuration using an extended domain and appropriate boundary conditions. Computations, run at two rotor stagger settings, show that the spanwise variation in relative flow angle onto the rotor aligns poorly to the rotor inlet metal angle. This leads to two dominant rotor loss sources: one at the tip associated with positive incidence and the second caused by negative incidence at lower span fractions. The second loss is reduced by opening the rotor stagger setting, and the first increases with rotor suction surface Mach number. The higher mass flow at more open rotor settings provide higher gross thrust, up to 49% of the forward take-off value, but is limited by the increased loss at high speed.
Modification of the Infinite-Dimensional Neutral-Type Time-Delay Dynamic Model for the Coupled Axial–Torsional Vibrations in Drill Strings With a Drag Bit
Authors: Tashakori Shabnam , Vossoughi Gholamreza , Zohoor Hassan , Yazdi Ehsan Azadi 
Published: March 2019

Abstract
Drill strings are subjected to complex coupled dynamics. Therefore, accurate dynamic modeling, which can represent the physical behavior of real drill strings, is of great importance for system analysis and control. The most widely used dynamic models for such systems are the lumped element models, which neglect the system distributed feature. In this paper, a dynamic model called neutral-type time delay model is modified to investigate the coupled axial–torsional vibrations in drill strings. This model is derived directly from the distributed parameter model by employing the d'Alembert method. Coupling of axial and torsional vibration modes occurs in the bit–rock interface. For the first time, the neutral-type time delay model is combined with a bit–rock interaction model that regards cutting process in addition to frictional contact. Moreover, mistakes made in some of the related previous studies are corrected. The resulting equations of motion are in terms of neutral-type delay differential equations with two constant delays, related to the oscillatory behavior of the system, and a state-dependent delay, induced by the bit–rock interaction. Illustrative simulation results are presented for a representative drill string, which demonstrates intense axial and torsional vibrations that may lead to system failure without a controller.
Negligible Effects of β-Hydroxy-β-Methylbutyrate Free Acid and Calcium Salt on Strength and Hypertrophic Responses to Resistance Training: A Randomized, Placebo-Controlled Study
Authors: Tritto Aline C. , Bueno Salomão , Rodrigues Rosa M.P. , Gualano Bruno , Roschel Hamilton , Artioli Guilherme G. 
Published: March 2019

This study evaluated the effects of β-hydroxy-β-methylbutyrate free acid (HMB-FA) and calcium salt (HMB-Ca) on strength, hypertrophy, and markers of muscle damage. In this randomized, double-blind, placebo-controlled study, 44 resistance-trained men (age: 26 ± 4 years; body mass: 84.9 ± 12.0 kg) consuming ≥1.7 g·kg−1·day−1 of protein received HMB-FA (3 g/day; n = 14), HMB-Ca (3 g/day; n = 15), or placebo (PL; cornstarch, 3 g/day; n = 15) for 12 weeks, while performing a periodized resistance training program. Before and after intervention, lean body mass (measured with dual X-ray absorptiometry), maximal dynamic strength (one-repetition maximum), knee extension maximal isometric strength (maximal voluntary isometric contraction [MVIC]), cross-sectional area (measured with ultrasound), and muscle soreness were assessed. MVIC was also measured 48 hr after the first and the last training sessions. All groups increased lean body mass (main time effect: p < .0001; HMB-FA: 1.8 ± 1.8 kg; HMB-Ca: 0.8 ± 1.4 kg; PL: 0.9 ± 1.4 kg), cross-sectional area (main time effect: p < .0001; HMB-FA: 6.6 ± 3.8%; HMB-Ca: 4.7 ± 4.4%; PL: 6.9 ± 3.8%), one-repetition maximum bench press (main time effect: p < .0001; HMB-FA: 14.8 ± 8.4 kg; HMB-Ca: 11.8 ± 7.4 kg; PL: 11.2 ± 6.6 kg), MVIC (main time effect: p < .0001; HMB-FA: 34.4 ± 39.3%; HMB-Ca: 32.3 ± 27.4%; PL: 17.7 ± 20.9%) after the intervention, but no differences between groups were shown. HMB-FA group showed greater leg press strength after the intervention than HMB-Ca and PL groups (Group × Time interaction: p < .05; HMB-FA: 47.7 ± 31.2 kg; HMB-Ca: 43.8 ± 31.7 kg; PL: 30.2 ± 20.9 kg). MVIC measured 48 hr after the first and the last sessions showed no attenuation of force decline with supplementation. Muscle soreness following the first and last sessions was not different between groups. The authors concluded that neither HMB-Ca nor HMB-FA improved hypertrophy or reduced muscle damage in resistance-trained men undergoing resistance training ingesting optimal amounts of protein. HMB-FA but not HMB-Ca resulted in a statistically significant yet minor improvement on leg press one-repetition maximum.
The Effects of Long Sprint Ability–Oriented Small-Sided Games Using Different Ratios of Players to Pitch Area on Internal and External Load in Soccer Players
Authors: Castagna Carlo , D’Ottavio Stefano , Cappelli Stefano , Araújo Póvoas Susana Cristina 
Published: March 2019

Purpose: To examine the internal and external load imposed by long sprint ability–oriented small-sided games (SSG) using different ratios of players to pitch area (densities) in soccer players. Methods: A total of 19 professional soccer players from the same soccer club (age = 17.1 [0.3] y, height = 1.76 [0.69] m, and body mass = 69.7 [9.4] kg) participated in this study. Players performed 4 × 30-s (150 s recovery) all-out 1-vs-1 SSG considering 300, 200, and 100 m2 per player (48 h apart). Players’ external loads were tracked with global positioning technology (20 Hz). Heart rate, blood lactate concentration (BLc), and rating of perceived exertion characterized players’ internal load. Peak BLc was assessed with a 30-s all-out test on a nonmotorized treadmill (NMT). Results: SSG300 produced higher BLc than SSG200 (moderate) and SSG100 (large). The SSG300, SSG200, and SSG100 BLc were 97.8% (34.8%), trivial; 74.7% (24.9%), moderate; and 43.4% (15.7%), large, of the NMT30s peak BLc, respectively. Players covered more distance at high intensity during the SSG300 than in other SSG conditions (huge to very large differences). High-intensity deceleration distance was largely lower in SSG200 than in SSG300. SSG100 elicited very large to huge and large to very large lower external load values than SSG300 and SSG200, respectively. Conclusions: The main finding of this study showed an inverse association between ball-drill density and internal/external loads in long sprint ability–oriented SSG. The SSG300 provided BLc closer to individual maximal, thus satisfying the all-out construct assumed for the development of long sprint ability. Further studies using the SSG300 as a training intervention and/or investigating other different SSG formats using the same density are warranted.
Turn Characteristics During Gait Differ With and Without a Cognitive Demand Among College Athletes
Authors: Brown Lauren A. , Hall Eric E. , Ketcham Caroline J. , Patel Kirtida , Buckley Thomas A. , Howell David R. , Vallabhajosula Srikant 
Published: March 2019

Context: Sports often involve complex movement patterns, such as turning. Although cognitive load effects on gait patterns are well known, little is known on how it affects biomechanics of turning gait among athletes. Such information could help evaluate how concussion affects turning gait required for daily living and sports. Objective: To determine the effect of a dual task on biomechanics of turning while walking among college athletes. Design: Cross-sectional study. Setting: University laboratory. Participants: Fifty-three participants performed 5 trials of a 20-m walk under single- and dual-task conditions at self-selected speed with a 180° turn at 10-m mark. The cognitive load included subtraction, spelling words backward, or reciting the months backward. Interventions: Not applicable. Main Outcome Measures: Turn duration, turning velocity, number of steps, SD of turn duration and velocity, and coefficient of variation of turn duration and velocity. Results: Participants turned significantly slower (155.99 [3.71] cm/s vs 183.52 [4.17] cm/s; P < .001) and took longer time to complete the turn (2.63 [0.05] s vs 2.33 [0.04] s; P < .001) while dual tasking, albeit taking similar number of steps to complete the turn. Participants also showed more variability in turning time under the dual-task condition (SD of turn duration = 0.39 vs 0.31 s; P = .004). Conclusions: Overall, college athletes turned slower and showed more variability during turning gait while performing a concurrent cognitive dual-task turning compared with single-task turning. The slower velocity increased variability may be representative of specific strategy of turning gait while dual tasking, which may be a result of the split attention to perform the cognitive task. The current study provides descriptive values of absolute and variability turning gait parameters for sports medicine personnel to use while they perform their concussion assessments on their college athletes.
Sex-Specific Dependence of Linear and Nonlinear Postural Control Metrics on Anthropometrics During Clinical Balance Tests in Healthy Young Adults
Authors: Glass Stephen M. , Cone Brian L. , Rhea Christopher K. , Duffy Donna M. , Ross Scott E. 
Published: March 2019

Context:Previous work suggests that balance behavior is a sex-dependent, complex process that can be characterized by linear and nonlinear metrics. Although a certain degree of center of pressure variability may be expected based on sexual dimorphism, there is evidence to suggest that these effects are obscured by potential interactions between sex and anthropometric factors. To date, no study has accounted for such interactive effects using both linear and nonlinear measures.Objective:This investigation sought to analyze interactive models featuring sex, height, and weight as predictors of linear and nonlinear aspects of postural control.Design:Cross-sectional study.Setting:Controlled laboratory.Participants:A total of 26 males (23.80 [3.44] y, 177.87 [6.44] cm, 81.70 [10.80] kg) and 28 females (21.14 [2.03] y, 169.57 [8.80] cm, 64.48 [8.86] kg) were sampled from a healthy university population.MainOutcomeMeasures:Linear (range [RNG], velocity [VEL], and SD) and nonlinear (detrended fluctuation analysis scaling exponent, multivariate multiscale sample entropy [MMSECI]) summary metrics of center of pressure time series.Procedure:Participants stood on a force plate for 20 seconds in 3 conditions: double (D), single (S), and tandem (T) stance. Data for each stance condition were analyzed using regression models with interaction terms for sex × height and sex × weight. In D, weight had a positive, significant main effect on VELy, MMSECId, and MMSECIv. In men, height was observed to have a positive effect on SDy (S), RNGy (S), and RNGx (T) and a negative effect on MMSECIv (T). In women, weight was observed to have a positive effect on SDy and VELx (both T).Conclusions:Our findings suggest that men and women differ with respect to certain linear and nonlinear aspects of balance behavior, and that these differences may reflect sex-specific behavioral patterns in addition to effects related to sexual dimorphism.
The Relationship Between the Golf-Specific Movement Screen and Golf Performance
Authors: Speariett Sophie , Armstrong Ross 
Published: March 2019

Context: Golf requires effective movement patterns to produce an effective swing and performance. Objective: To determine the relationship between the Titleist Performance Institute golf-specific functional movement screening (GSFMS) composite and individual element scores and golf performance by assessing a player’s handicap, clubhead speed, side accuracy, ball speed, peak pelvis rotation speed, swing sequence, and common swing faults. Design: Cohort study, clinical measurement. Setting: English golf club. Participants: A total of 11 amateur golfers: 5 males (age: 37.2 [18.7] y, height: 184.4 [9.6] cm, body mass: 89.5 [13.4] kg, and handicap: 9 [6.6]) and 6 females (age: 53.7 [15.0] y, height: 166.8 [5.5] cm, body mass: 67.9 [16.6] kg, and handicap: 13 [6.1]). Main Outcome Measures: GSFMS composite and individual element scores and golf performance variables. Results: Significant relationships existed between GSFMS composite scores and handicap (r = −.779, P = .01); clubhead speed (r = .701, P = .02); ball speed (r = .674, P = .02); and peak pelvis rotation speed (r = .687, P = .02). Significant relationships existed between 90°/90° golf position and clubhead speed (r = .716, P = .01); ball speed (r = .777, P = .01); seated trunk rotation and peak pelvis rotation speed (r = .606, P = .048); single-leg balance and handicap (r = −.722, P = .01); torso rotation and handicap (r = −.637,P = .04); and torso rotation and peak pelvis rotation speed (r = .741, P = .01). Single-leg balance, overhead deep squat, and pelvic tilt were the GSFMS tests which participants had most difficulty in performing. The most common swing faults identified included loss of posture, slide, chicken winging, and early hip extension. Conclusions: The GSFMS may be used to identify movement limitations that relate to golfing performance. These findings may potentially allow intervention to correct movement patterns and potentially improve golf performance.
Associations of nicotine dependence and fat distribution in Chinese male adults: a cross-sectional study in Lanxi, China
Authors: Wei Chen , Ye Sunyue , Sheng Jessica Ruolin , Ma Xiaoguang , Ru Yuan , Zhang Liang , Guo Huilan , Zhu Shankuan 
Published: March 2019

IntroductionPrevious studies have showed association between smoking and central fat distribution. However, the impact of smoking on whole body fat distribution, particularly peripheral fat distribution remains unclear.MethodsNicotine dependence was assessed in a total of 1264 male adults aged 18–80 years using the Fagerström Test for Nicotine Dependence (FTND). Smoking status was categorised as non-smokers, former and current smokers with very low, low/moderate, or high FTND scores. Body fat distribution was determined using the dual energy X-ray absorptiometry and anthropometric measurements. Multivariable linear regression models were applied to examine the adjusted associations between body fat distribution and smoking in all participants, and its association with FTND scores in the current smokers.ResultsGreater waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), trunk fat percentage (%TF), android fat percentage (%AF) and android-to-gynoid fat mass ratio (AOI); but lower legs fat percentage (%LegF), limb fat percentage (%LimbF) and gynoid fat percentage (%GF) were found in current smokers with high FTND scores compared with non-smokers. In current smokers aged 60 years or older, FTND scores had positive associations with WC, WHR, WHtR, %TF, %AF and AOI, and negative associations with %LegF, %LimbF and %GF.ConclusionsNicotine dependence was positively associated with central fat distribution and negatively associated with peripheral fat distribution in Chinese male adults, particularly in those older or heavy smokers, and these associations were independent from body mass index, which might be due to long exposure to smoking.
Relationship between serum osteocalcin/undercarboxylated osteocalcin and type 2 diabetes: a systematic review/meta-analysis study protocol
Authors: Liu Yihui , Liu Xiaoying , R Lewis Joshua , Brock Kaye , C Brennan-Speranza Tara , Teixeira-Pinto Armando 
Published: March 2019

IntroductionThe global burden of type 2 diabetes (T2DM) is steadily increasing. Experimental studies have demonstrated that a novel hormone secreted by bone cells, osteocalcin (OC), can stimulate beta-cell proliferation and improve insulin sensitivity in mice. Observational studies in humans have investigated the relationship between OC and metabolic parameters, and T2DM. Importantly, few studies have reported on the undercarboxylated form of OC (ucOC), which is the putative active form of OC suggested to affect glucose metabolism.ObjectivesWe will conduct a systematic review and meta-analysis to: (1) compare the levels of serum OC and ucOC between T2DM and normal glucose-tolerant controls (NGC); (2) investigate the risk ratios between serum OC and ucOC, and T2DM; (3) determine the correlation coefficient between OC and ucOC and fasting insulin levels, homeostatic model assessment-insulin resistance, haemoglobin A1c and fasting glucose levels and (4) explore potential sources of between-study heterogeneity. The secondary objective is to compare the serum OC and ucOC between pre-diabetes (PD) and NGC and between T2DM and PD.hods and analysisThis study will report items in line with the guidelines outlined in preferred reporting items for systematic reviews and meta-analysis of observational studies in epidemiology. We will include observational studies (cohort, case-control and cross-sectional studies) and intervention studies with baseline data. Three databases (MEDLINE, EMBASE and SCOPUS) will be searched from inception until July 2018 without language restrictions. Two reviewers will independently screen the titles and abstracts and conduct a full-text assessment to identify eligible studies. Discrepancies will be resolved by consensus with a third reviewer. The risk of bias assessment will be conducted by two reviewers independently based on the Newcastle-Ottawa Scale. Potential sources of between-study heterogeneity will be tested using meta-regression/subgroup analyses. Contour-enhanced funnel plots and Egger’s test will be used to identify potential publication bias.Ethics and disseminationFormal ethical approval is not required. We will disseminate the results to a peer-reviewed publication and conference presentation.PROSPERO registration numberCRD42017073127.
Capturing the experience of the hospital-stay journey from admission to discharge using diaries completed by patients in their own words: a qualitative study
Authors: Webster Craig S , Jowsey Tanisha , Lu Lucy M , Henning Marcus A , Verstappen Antonia , Wearn Andy , Reid Papaarangi M , Merry Alan F , Weller Jennifer M 
Published: March 2019

ObjectiveTo capture and better understand patients’ experience during their healthcare journey from hospital admission to discharge, and to identify patient suggestions for improvement.DesignProspective, exploratory, qualitative study. Patients were asked to complete an unstructured written diary expressed in their own words, recording negative and positive experiences or anything else they considered noteworthy.Participants and settingPatients undergoing vascular surgery in a metropolitan hospital.Primary outcome measuresComplete diary transcripts underwent a general inductive thematic analysis, and opportunities to improve the experience of care were identified and collated.ResultsWe recruited 113 patients in order to collect 80 completed diaries from 78 participants (a participant response rate of 69%), recording patients’ experiences of their hospital-stay journey. Participating patients were a median (range) age of 69 (21–99) years and diaries contained a median (range) of 197 (26–1672) words each. Study participants with a tertiary education wrote more in their diaries than those without—a median (range) of 353.5 (48–1672) vs 163 (26–1599) words, respectively (Mann-Whitney U test, p=0.001). Three primary and eight secondary themes emerged from analysis of diary transcripts—primary themes being: (1) communication as central to care; (2) importance of feeling cared for and (3) environmental factors shaping experiences. In the great majority, participants reported positive experiences on the hospital ward. However, a set of 12 patient suggestions for improvement were identified, the majority of which could be addressed with little cost but result in substantial improvements in patient experience. Half of the 12 suggestions for improvement fell into primary theme 1, concerning opportunities to improve communication between healthcare providers and patients.ConclusionsUnstructured diaries completed in a patient’s own words appear to be an effective and simple approach to capture the hospital-stay experience from the patient’s own perspective, and to identify opportunities for improvement.
Canadian neurosurgeons’ views on medical assistance in dying (MAID): a cross-sectional survey of Canadian Neurosurgical Society (CNSS) members
Authors: Althagafi Alwalaa , Ekong Chris , Wheelock Brian W , Moulton Richard , Gorman Peter , Reddy Kesh , Christie Sean , Fleetwood Ian , Barry Sean 
Published: March 2019

BackgroundThe Supreme Court of Canada removed the prohibition on physicians assisting in patients dying on 6 February 2015. Bill C-14, legalising medical assistance in dying (MAID) in Canada, was subsequently passed by the House of Commons and the Senate on 17 June 2016. As this remains a divisive issue for physicians, the Canadian Neurosurgical Society (CNSS) has recently published a position statement on MAID.MethodsWe conducted a cross-sectional survey to understand the views and perceptions among CNSS members regarding MAID to inform its position statement on the issue. Data was collected from May to June 2016.ResultsOf the 300 active membes of the CNSS who recevied the survey, 89 respondents completed the survey, 71% of whom were attending neurosurgeons and 29% were neurosurgery residents. Most respondents,74.2%, supported the right of physicians to participate in MAID with 7.8% opposing. 37% had current patients in their practice fitting the criteria for MAID. 23.6% had been asked by patients to assist with MAID, but only 11% would consider personally providing it. 84% of neurosurgeons surveyed supported the physicians’ right to conscientious objection to MAID while 21% thought attending surgeons should be removed from the inquiry and decision-making process. 43.8% agreed that the requirment to refer a patient to a MAID service should be mandatory. Glioblastoma multiforme (65%), quadriplegia/quadriparesis secondary to spinal tumour/trauma (54%) and Parkinson’s disease (24%) were the most common suggested potential indications for MAID among the neurosurgical population.ConclusionsOur results demonstrate that most neurosurgeons in Canada are generally supportive of MAID in select patients. However, they also strongly support the physicians’ right to conscientious objection.