scholarly journals Foot Strike Patterns Differ Between Children and Adolescents Growing up Barefoot vs. Shod

2017 ◽  
Vol 39 (02) ◽  
pp. 97-103 ◽  
Author(s):  
Karsten Hollander ◽  
Johanna de Villiers ◽  
Ranel Venter ◽  
Susanne Sehner ◽  
Karl Wegscheider ◽  
...  
Keyword(s):  
South Africa ◽  
Logistic Regression ◽  
Children And Adolescents ◽  
High Speed ◽  
Mixed Effects ◽  
High Speed Camera ◽  
Growing Up ◽  
Barefoot Running ◽  
Age Dependent ◽  
Foot Strike

AbstractEffects of early and permanent footwear use are not well understood. The aim of this study was to investigate the effects of habituation to footwear on foot strike patterns of children and adolescents. Healthy habitually barefoot and shod participants (aged 6–18 years) from South Africa (n=288) and Germany (n=390) performed multiple 20-m jogging and running trials with and without shoes. Each foot strike was captured using a high-speed camera to determine a rearfoot or non-rearfoot strike. The probability of a rearfoot strike in both cohorts and each age was analyzed by using a mixed-effects logistic regression adjusted for possible confounders. Habitually barefoot children showed a higher probability of using rearfoot strikes than habitually shod children (p<0.001). The probability was age-dependent and decreased in habitually barefoot children with age (ORbarefoot-jogging=0.82, 95% CI, 0.71 to 0.96, p=0.014; ORbarefoot-running=0.58, 95% CI, 0.50 to 0.67, p<0.001 and ORshod-running=0.68, 95% CI, 0.59 to 0.79, p<0.001). In habitually shod children, the probability increased significantly for shod jogging (OR=1.19, 95% CI, 1.05 to 1.35, p=0.006). To conclude, foot strike patterns of children are influenced by habituation to footwear. Younger habitually barefoot children show higher rates of rearfoot strikes for shod and barefoot running, and it converges in later adolescence.

scholarly journals Kinematic characteristics of barefoot sprinting in habitually shod children

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5188
Author(s):  
Jun Mizushima ◽  
Keitaro Seki ◽  
Justin W.L. Keogh ◽  
Kei Maeda ◽  
Atsushi Shibata ◽  
...  
Keyword(s):  
High Speed ◽  
Sagittal Plane ◽  
Step Length ◽  
Standing Position ◽  
Future Research ◽  
Step Frequency ◽  
Barefoot Running ◽  
Foot Strike ◽  
Spatio Temporal ◽  
The Right

Background Anecdotally, a wide variety of benefits of barefoot running have been advocated by numerous individuals. The influence of the alterations in the properties of the shoe on the running movement has been demonstrated in adults at submaximal jogging speeds. However, the biomechanical differences between shod and barefoot running in children at sprinting speeds and the potential developmental implications of these differences are still less examined. The purpose was to determine the potential differences in habitually shod children’s sprint kinematics between shod and barefoot conditions. Methods Ninety-four children (51 boys and 43 girls; 6–12 years-old; height, 135.0 ± 0.12 m; body mass, 29.0 ± 6.9 kg) performed 30 m maximal sprints from standing position for each of two conditions (shod and barefoot). To analyze sprint kinematics within sagittal plane sprint kinematics, a high-speed camera (300 fps) was set perpendicular to the runway. In addition, sagittal foot landing and take-off images were recorded for multiple angles by using five high-speed cameras (300 fps). Spatio-temporal variables, the kinematics of the right leg (support leg) and the left leg (recovery leg), and foot strike patterns: rear-foot strike (RFS), mid-foot strike (MFS), and fore-foot strike (FFS) were investigated. The paired t-test was used to test difference between shod and barefoot condition. Results Barefoot sprinting in habitually shod children was mainly characterized by significantly lower sprint speed, higher step frequency, shorter step length and stance time. In shod running, 82% of children showed RFS, whereas it decreased to 29% in barefoot condition. The touch down state and the subsequent joint movements of both support and recovery legs during stance phase were significantly altered when running in condition with barefoot. Discussion The acute effects of barefoot sprinting was demonstrated by significantly slower sprinting speeds that appear to reflect changes in a variety of spatiotemporal parameters as well as lower limb kinematics. It is currently unknown whether such differences would be observed in children who typically run in bare feet and what developmental benefits and risks may emerge from increasing the proportion of barefoot running and sprinting in children. Future research should therefore investigate potential benefits that barefoot sprinting may have on the development of key physical fitness such as nerve conduction velocity, muscular speed, power, and sprinting technique and on ways to minimize the risk of any acute or chronic injuries associated with this activity.

scholarly journals Impact of digitally acquired peer diagnostic input on diagnostic confidence in outpatient cases: A pragmatic randomized trial

2020 ◽  
Author(s):  
Elaine C Khoong ◽  
Valy Fontil ◽  
Natalie A Rivadeneira ◽  
Mekhala Hoskote ◽  
Shantanu Nundy ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Randomized Trial ◽  
Odds Ratio ◽  
Primary Outcome ◽  
Mixed Effects ◽  
Regression Analyses ◽  
Diagnostic Confidence ◽  
Diagnostic Uncertainty ◽  
Intervention Impact ◽  
High Uncertainty

Abstract Objective The study sought to evaluate if peer input on outpatient cases impacted diagnostic confidence. Materials and Methods This randomized trial of a peer input intervention occurred among 28 clinicians with case-level randomization. Encounters with diagnostic uncertainty were entered onto a digital platform to collect input from ≥5 clinicians. The primary outcome was diagnostic confidence. We used mixed-effects logistic regression analyses to assess for intervention impact on diagnostic confidence. Results Among the 509 cases (255 control; 254 intervention), the intervention did not impact confidence (odds ratio [OR], 1.46; 95% confidence interval [CI], 0.999-2.12), but after adjusting for clinician and case traits, the intervention was associated with higher confidence (OR, 1.53; 95% CI, 1.01-2.32). The intervention impact was greater in cases with high uncertainty (OR, 3.23; 95% CI, 1.09- 9.52). Conclusions Peer input increased diagnostic confidence primarily in high-uncertainty cases, consistent with findings that clinicians desire input primarily in cases with continued uncertainty.

scholarly journals Tracking by Deblatting

2021 ◽  
Author(s):  
Denys Rozumnyi ◽  
Jan Kotera ◽  
Filip Šroubek ◽  
Jiří Matas
Keyword(s):  
High Speed ◽  
High Performance ◽  
Motion Blur ◽  
Velocity Estimation ◽  
High Speed Camera ◽  
Trajectory Function ◽  
Novel Approach ◽  
Blind Deblurring ◽  
Object Trajectories ◽  
Complex Trajectories

AbstractObjects moving at high speed along complex trajectories often appear in videos, especially videos of sports. Such objects travel a considerable distance during exposure time of a single frame, and therefore, their position in the frame is not well defined. They appear as semi-transparent streaks due to the motion blur and cannot be reliably tracked by general trackers. We propose a novel approach called Tracking by Deblatting based on the observation that motion blur is directly related to the intra-frame trajectory of an object. Blur is estimated by solving two intertwined inverse problems, blind deblurring and image matting, which we call deblatting. By postprocessing, non-causal Tracking by Deblatting estimates continuous, complete, and accurate object trajectories for the whole sequence. Tracked objects are precisely localized with higher temporal resolution than by conventional trackers. Energy minimization by dynamic programming is used to detect abrupt changes of motion, called bounces. High-order polynomials are then fitted to smooth trajectory segments between bounces. The output is a continuous trajectory function that assigns location for every real-valued time stamp from zero to the number of frames. The proposed algorithm was evaluated on a newly created dataset of videos from a high-speed camera using a novel Trajectory-IoU metric that generalizes the traditional Intersection over Union and measures the accuracy of the intra-frame trajectory. The proposed method outperforms the baselines both in recall and trajectory accuracy. Additionally, we show that from the trajectory function precise physical calculations are possible, such as radius, gravity, and sub-frame object velocity. Velocity estimation is compared to the high-speed camera measurements and radars. Results show high performance of the proposed method in terms of Trajectory-IoU, recall, and velocity estimation.

Influence of Main Swirler Vane Angle on the Ignition Performance of TeLESS-II Combustor

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Bo Wang ◽  
Chi Zhang ◽  
Yuzhen Lin ◽  
Xin Hui ◽  
Jibao Li
Keyword(s):  
High Speed ◽  
Inlet Temperature ◽  
Main Stage ◽  
Ignition Process ◽  
High Speed Camera ◽  
Fuel Distribution ◽  
Fuel Droplets ◽  
Planar Laser ◽  
Cfd Method ◽  
Vane Angle

In order to balance the low emission and wide stabilization for lean premixed prevaporized (LPP) combustion, the centrally staged layout is preferred in advanced aero-engine combustors. However, compared with the conventional combustor, it is more difficult for the centrally staged combustor to light up as the main stage air layer will prevent the pilot fuel droplets arriving at igniter tip. The goal of the present paper is to study the effect of the main stage air on the ignition of the centrally staged combustor. Two cases of the main swirler vane angle of the TeLESS-II combustor, 20 deg and 30 deg are researched. The ignition results at room inlet temperature and pressure show that the ignition performance of the 30 deg vane angle case is better than that of the 20 deg vane angle case. High-speed camera, planar laser induced fluorescence (PLIF), and computational fluids dynamics (CFD) are used to better understand the ignition results. The high-speed camera has recorded the ignition process, indicated that an initial kernel forms just adjacent the liner wall after the igniter is turned on, the kernel propagates along the radial direction to the combustor center and begins to grow into a big flame, and then it spreads to the exit of the pilot stage, and eventually stabilizes the flame. CFD of the cold flow field coupled with spray field is conducted. A verification of the CFD method has been applied with PLIF measurement, and the simulation results can qualitatively represent the experimental data in terms of fuel distribution. The CFD results show that the radial dimensions of the primary recirculation zone of the two cases are very similar, and the dominant cause of the different ignition results is the vapor distribution of the fuel. The concentration of kerosene vapor of the 30 deg vane angle case is much larger than that of the 20 deg vane angle case close to the igniter tip and along the propagation route of the kernel, therefore, the 30 deg vane angle case has a better ignition performance. For the consideration of the ignition performance, a larger main swirler vane angle of 30 deg is suggested for the better fuel distribution when designing a centrally staged combustor.

scholarly journals Leader-chasing behavior in negative artificial triggered lightning flashes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fukun Wang ◽  
Jianguo Wang ◽  
Li Cai ◽  
Rui Su ◽  
Wenhan Ding ◽  
...  
Keyword(s):  
High Speed ◽  
The Other ◽  
Lightning Flash ◽  
High Speed Camera ◽  
Return Stroke ◽  
Catching Up ◽  
Special Cases ◽  
Triggered Lightning

AbstractTwo special cases of dart leader propagation were observed by the high-speed camera in the leader/return stroke sequences of a classical triggered lightning flash and an altitude-triggered lightning flash, respectively. Different from most of the subsequent return strokes preceded by only one leader, the return stroke in each case was preceded by two leaders occurring successively and competing in the same channel, which herein is named leader-chasing behavior. In one case, the polarity of the latter leader was opposite to that of the former leader and these two combined together to form a new leader, which shared the same polarity with the former leader. In the other case, the latter leader shared the same polarity with the former leader and disappeared after catching up with the former leader. The propagation of the former leader in this case seems not to be significantly influenced by the existence of the latter leader.

scholarly journals Surgical Site Infection Trend Analysis Following Abdominal Hysterectomy, National Healthcare Safety Network, 2009–2018

2020 ◽  
Vol 41 (S1) ◽  
pp. s396-s397
Author(s):  
Qunna Li ◽  
Minn Soe ◽  
Allan Nkwata ◽  
Victoria Russo ◽  
Margaret Dudeck ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Trend Analysis ◽  
Primary Closure ◽  
Abdominal Hysterectomy ◽  
Incidence Rates ◽  
Mixed Effects ◽  
Mandatory Reporting ◽  
Hospital Inpatient ◽  
Quality Reporting ◽  
Reporting Requirement

Background: Surveillance data for surgical site infections (SSIs) following abdominal hysterectomy (HYST) have been reported to the CDC NHSN since 2005. Beginning in 2012, HYST SSI surveillance coverage expanded substantially as a result of a CMS mandatory reporting requirement as part of the Hospital Inpatient Quality Reporting Program. A trend analysis of HYST SSI using data submitted to the NHSN has not been previously reported. To estimate the overall trend of HYST SSI incidence rates, we analyzed data reported from acute-care hospitals with surgery performed between January 1, 2009, and December 31, 2018. Methods: We analyzed inpatient adult HYST procedures with primary closure resulting deep incisional primary and organ-space SSIs detected during the same hospitalization or rehospitalization to the same hospital. SSIs reported as infection present at time of surgery (PATOS) were included in the analysis. Due to the surveillance definition changes for primary closure in 2013 and 2015, these were tested separately as interruptions to HYST SSI outcome using an interrupted time-series model with a mixed-effects logistic regression. Because the previously described changes were not significantly associated with changes in HYST SSI risk, mixed-effects logistic regression was used to estimate the annual change in the log odds of HYST SSI. The estimates were adjusted for the following covariates: hospital bed size, general anesthesia, scope, ASA score, wound classification, medical school affiliation type, procedure duration and age. Results: The number of hospitals and procedures reported to NHSN for HYST increased and then stabilized after 2012 (Table 1). The unadjusted annual SSI incidence rates ranged from 0.60% to 0.81%. Based on the model, we estimate a 2.58% decrease in the odds of having a HYST SSI annually after controlling for variables mentioned above (Table 2). Conclusions: The volume of hospitals and procedures for HYST reported to NHSN increased substantially because of the CMS reporting requirement implemented in 2012. The overall adjusted HYST SSI odds ratio decreased annually over 2009–2018, which indicates progress in preventing HYST SSIs.Funding: NoneDisclosures: None

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