Background:A previous study has reported a 50% reduction in disuse atrophy of the quadriceps during the first 14 days after anterior cruciate ligament(ACL) reconstruction.A follow-up trial is needed to confirm these p...Background:A previous study has reported a 50% reduction in disuse atrophy of the quadriceps during the first 14 days after anterior cruciate ligament(ACL) reconstruction.A follow-up trial is needed to confirm these promising results.The present study aims to investigate the effect of an occlusion stimulus on quadriceps atrophy after ACL reconstruction.Methods:A total of 24 subjects participated in the study.They were randomized into two groups.Starting the 2nd day after surgery,the occlusion group received an occlusion stimulus for 5 min,followed by removal of the occlusive pressure for 3 min.This was repeated five times in one training session,twice daily.During the period of occlusive stimulus,the subjects performed 20 low load exercises for the quadriceps.The control group followed the same exercise protocol,but without the occlusion stimulus.Changes in quadriceps anatomical cross section area(ACSA) were measured using axial magnetic resonance(MR) images at 40% and 50% of the length of the femur.Results:Both groups had a significant reduction of quadriceps ACSA from 2 days before surgery to 16 days after surgery.During the intervention period,the occlusion group lost 13.8% ± 1.1%(mean ± SEM) and the control group lost 13.1% ± 1.0% of their quadriceps ACSA,respectively.There was no significant difference between the occlusion and control groups with regards to atrophy of the quadriceps muscles.Conclusion:In conflict with other studies using a similar protocol,application of blood flow restriction the first 14 days after ACL reconstruction did not reduce quadriceps ACSA muscle atrophy measured by MR in a population of athletes.展开更多
The vehicle-track-bridge(VTB)element was used to investigate how a high-speed railway bridge reacted when it was subjected to near-fault directivity pulse-like ground motions.Based on the PEER NAG Strong Ground Motion...The vehicle-track-bridge(VTB)element was used to investigate how a high-speed railway bridge reacted when it was subjected to near-fault directivity pulse-like ground motions.Based on the PEER NAG Strong Ground Motion Database,the spatial analysis model of a vehicle-bridge system was developed,the VTB element was derived to simulate the interaction of train and bridge,and the elasto-plastic seismic responses of the bridge were calculated.The calculation results show that girder and pier top displacement,and bending moment of the pier base increase subjected to near-fault directivity pulse-like ground motion compared to far-field earthquakes,and the greater deformation responses in near-fault shaking are associated with fewer reversed cycles of loading.The hysteretic characteristics of the pier subjected to a near-fault directivity pulse-like earthquake should be explicitly expressed as the bending moment-rotation relationship of the pier base,which is characterized by the centrally strengthened hysteretic cycles at some point of the loading time-history curve.The results show that there is an amplification of the vertical deflection in the girder's mid-span owing to the high vertical ground motion.In light of these findings,the effect of the vertical ground motion should be used to adjust the unconservative amplification constant 2/3 of the vertical-to-horizontal peak ground motion ratio in the seismic design of bridge.展开更多
Purpose： The purpose of this study was to examine the effects of landing kinematics and electromyographic （EMG） activities of medial gastrocnemius on a combined inversion and plantarflexion surface on the ankle （M...Purpose： The purpose of this study was to examine the effects of landing kinematics and electromyographic （EMG） activities of medial gastrocnemius on a combined inversion and plantarflexion surface on the ankle （MG）, peroneus longus （PL）, and tibialis anterior （TA） muscles. Methods： Twelve recreational athletes performed five drop landings from an overhead bar of 30 cm height on to three surfaces： a flat surface, a 25° inversion surface, and a combined surface of 25° inversion and 25° plantarflexion. The kinematic variables and integrated EMG （IEMG） of the three muscles were assessed using a one-way repeated measures ANOVA and a 3 × 3 （surface × muscle） ANOVA, respectively （p 〈 0.05）. Results： The IEMG results showed a significant muscle by surface interaction. The flat surface induced higher TA activity than the two tilted surfaces. The inverted surface produced significantly higher inversion peak angle and velocity than the flat surface, but similar PL activity across the surfaces. The MG IEMG, ankle plantarflexion angle, and inversion range of motion were significantly higher for the combined surface compared to the inverted surface. Conclusion： These findings suggest that compared to the inversion surface, the combined plantarflexion and inversion surface seems to provide a more unstable surface condition for lateral ankle sprains during landing.展开更多
Group-invariant solutions to certain plane curve motions in Euclidean and centro-affine geometries areobtained. The behavior of some solutions is also presented.
A novel method to infer the finger flexing motions of various arm postures is proposed. From the gyroscope signal, the authors recognized forearm posture using K-means clustering method. Then finger motion inferred. F...A novel method to infer the finger flexing motions of various arm postures is proposed. From the gyroscope signal, the authors recognized forearm posture using K-means clustering method. Then finger motion inferred. For finger motion inference, Gaussian model of information entropy and maximum likelibood method was utilized. Experimentally it is obtained that the average recognition rate with the forearm posture inference is much higher than those without the inference by 30.7%.展开更多
This paper aims at investigating the efficacy of different state-of-art damage detection methods when applied to real worm structures subjected to ground motion excitations, for which the literature contributions are,...This paper aims at investigating the efficacy of different state-of-art damage detection methods when applied to real worm structures subjected to ground motion excitations, for which the literature contributions are, at present, still not fully comprehensive. To this purpose the paper analyses two test structures： （1） a four-story scaled steel frame tested on a shake table in a controlled laboratory conditions, and （2） a seven-story reinforced concrete building monitored during the seismic excitations of the 1999 Chi-Chi （Taiwan） Earthquake main shock and numerous fore and afiershocks. Some model based damage approaches and statistics based damage indexes are reviewed. The different methodologies and indexes are, then, applied to the two test structures with the final aim of analysing their performance and validity within the case of a laboratory scaled model and a real world structure subjected to input ground motion.展开更多
文摘Background:A previous study has reported a 50% reduction in disuse atrophy of the quadriceps during the first 14 days after anterior cruciate ligament(ACL) reconstruction.A follow-up trial is needed to confirm these promising results.The present study aims to investigate the effect of an occlusion stimulus on quadriceps atrophy after ACL reconstruction.Methods:A total of 24 subjects participated in the study.They were randomized into two groups.Starting the 2nd day after surgery,the occlusion group received an occlusion stimulus for 5 min,followed by removal of the occlusive pressure for 3 min.This was repeated five times in one training session,twice daily.During the period of occlusive stimulus,the subjects performed 20 low load exercises for the quadriceps.The control group followed the same exercise protocol,but without the occlusion stimulus.Changes in quadriceps anatomical cross section area(ACSA) were measured using axial magnetic resonance(MR) images at 40% and 50% of the length of the femur.Results:Both groups had a significant reduction of quadriceps ACSA from 2 days before surgery to 16 days after surgery.During the intervention period,the occlusion group lost 13.8% ± 1.1%(mean ± SEM) and the control group lost 13.1% ± 1.0% of their quadriceps ACSA,respectively.There was no significant difference between the occlusion and control groups with regards to atrophy of the quadriceps muscles.Conclusion:In conflict with other studies using a similar protocol,application of blood flow restriction the first 14 days after ACL reconstruction did not reduce quadriceps ACSA muscle atrophy measured by MR in a population of athletes.
基金Project(2013CB036203)supported by the National Basic Research Program of ChinaProject(2013M530022)supported by China Postdoctoral Science Foundation+4 种基金Project(2013-K5-31)supported by Science and Technology Plan of Ministry of Housing and Urban-Rural Development of ChinaProject supported by High-level Scientific Research Foundation for the Introduction of Talent of Yangzhou University,ChinaProject supported by the Open Fund of the National Engineering Laboratory for High Speed Railway Construction,ChinaProject(IRT1296)supported by the Program for Changjiang Scholars and Innovative Research Team in University,ChinaProject(50908236)supported by the National Natural Science Foundation of China
文摘The vehicle-track-bridge(VTB)element was used to investigate how a high-speed railway bridge reacted when it was subjected to near-fault directivity pulse-like ground motions.Based on the PEER NAG Strong Ground Motion Database,the spatial analysis model of a vehicle-bridge system was developed,the VTB element was derived to simulate the interaction of train and bridge,and the elasto-plastic seismic responses of the bridge were calculated.The calculation results show that girder and pier top displacement,and bending moment of the pier base increase subjected to near-fault directivity pulse-like ground motion compared to far-field earthquakes,and the greater deformation responses in near-fault shaking are associated with fewer reversed cycles of loading.The hysteretic characteristics of the pier subjected to a near-fault directivity pulse-like earthquake should be explicitly expressed as the bending moment-rotation relationship of the pier base,which is characterized by the centrally strengthened hysteretic cycles at some point of the loading time-history curve.The results show that there is an amplification of the vertical deflection in the girder's mid-span owing to the high vertical ground motion.In light of these findings,the effect of the vertical ground motion should be used to adjust the unconservative amplification constant 2/3 of the vertical-to-horizontal peak ground motion ratio in the seismic design of bridge.
文摘Purpose： The purpose of this study was to examine the effects of landing kinematics and electromyographic （EMG） activities of medial gastrocnemius on a combined inversion and plantarflexion surface on the ankle （MG）, peroneus longus （PL）, and tibialis anterior （TA） muscles. Methods： Twelve recreational athletes performed five drop landings from an overhead bar of 30 cm height on to three surfaces： a flat surface, a 25° inversion surface, and a combined surface of 25° inversion and 25° plantarflexion. The kinematic variables and integrated EMG （IEMG） of the three muscles were assessed using a one-way repeated measures ANOVA and a 3 × 3 （surface × muscle） ANOVA, respectively （p 〈 0.05）. Results： The IEMG results showed a significant muscle by surface interaction. The flat surface induced higher TA activity than the two tilted surfaces. The inverted surface produced significantly higher inversion peak angle and velocity than the flat surface, but similar PL activity across the surfaces. The MG IEMG, ankle plantarflexion angle, and inversion range of motion were significantly higher for the combined surface compared to the inverted surface. Conclusion： These findings suggest that compared to the inversion surface, the combined plantarflexion and inversion surface seems to provide a more unstable surface condition for lateral ankle sprains during landing.
文摘Group-invariant solutions to certain plane curve motions in Euclidean and centro-affine geometries areobtained. The behavior of some solutions is also presented.
基金supported by the MKE(The Ministry of Knowledge Economy),Koreathe ITRC(Information Technology Research Center)support program(NIPA-2010-C1090-1021-0010)
文摘A novel method to infer the finger flexing motions of various arm postures is proposed. From the gyroscope signal, the authors recognized forearm posture using K-means clustering method. Then finger motion inferred. For finger motion inference, Gaussian model of information entropy and maximum likelibood method was utilized. Experimentally it is obtained that the average recognition rate with the forearm posture inference is much higher than those without the inference by 30.7%.
文摘This paper aims at investigating the efficacy of different state-of-art damage detection methods when applied to real worm structures subjected to ground motion excitations, for which the literature contributions are, at present, still not fully comprehensive. To this purpose the paper analyses two test structures： （1） a four-story scaled steel frame tested on a shake table in a controlled laboratory conditions, and （2） a seven-story reinforced concrete building monitored during the seismic excitations of the 1999 Chi-Chi （Taiwan） Earthquake main shock and numerous fore and afiershocks. Some model based damage approaches and statistics based damage indexes are reviewed. The different methodologies and indexes are, then, applied to the two test structures with the final aim of analysing their performance and validity within the case of a laboratory scaled model and a real world structure subjected to input ground motion.
