To explore the mechanisms underlying exercise-induced local muscle fatigue in patients with idiopathic Parkinson＇s disease （PD）,we used surface electromyography to record myoelectric signals from the tibialis anter...To explore the mechanisms underlying exercise-induced local muscle fatigue in patients with idiopathic Parkinson＇s disease （PD）,we used surface electromyography to record myoelectric signals from the tibialis anterior muscle during isometric contraction-induced fatigue until exhaustion.The results revealed no significant differences between patients with idiopathic PD and healthy controls in maximum voluntary contraction of the tibialis anterior muscle.The basic characteristics of surface electromyography were also similar between the two groups.The duration of isometric contraction at 50% maximum voluntary contraction was shortened in PD patients.In addition,PD patients exhibited a stronger increase in mean square amplitude,but a weaker decrease in median frequency and mean power frequency compared with healthy controls during isometric contraction.The skeletal muscles of PD patients revealed specificity of surface electromyography findings,indicating increased fatigability compared with healthy controls.展开更多
With the rapid development of the offshore oil industries, submarine oil / gas pipelines have been widely used. Under the complicated submarine environmental conditions, the dynamic characteristics of pipelines show s...With the rapid development of the offshore oil industries, submarine oil / gas pipelines have been widely used. Under the complicated submarine environmental conditions, the dynamic characteristics of pipelines show some new features due to the existence of both internal and external flows. The paper is intended to investigate the vortex-induced vibration of the suspended pipeline span exposed to submarine steady flow. Especially, the effects of the flow inside the pipeline are taken into account. Its influences on the amplitude of pipeline response, and then on the fatigue life, are given in terms of the velocity of the internal flow.展开更多
BACKGROUND Fibromyalgia(FM)and myalgic encephalomyelitis/chronic fatigue syndrome(ME/CFS)are devastating metabolic neuroimmune diseases that are difficult to diagnose because of the presence of numerous symptoms and a...BACKGROUND Fibromyalgia(FM)and myalgic encephalomyelitis/chronic fatigue syndrome(ME/CFS)are devastating metabolic neuroimmune diseases that are difficult to diagnose because of the presence of numerous symptoms and a lack of specific biomarkers.Despite patient heterogeneity linked to patient subgroups and variation in disease severity,anomalies are found in the blood and plasma of these patients when compared with healthy control groups.The seeming specificity of these“plasma factors”,as recently reported by Ron Davis and his group at Stanford University,CA,United States,and observations by our group,have led to the proposal that induced pluripotent stem cells(iPSCs)may be used as metabolic sensors for FM and ME/CFS,a hypothesis that is the basis for this indepth review.AIM To identify metabolic signatures in FM and/or ME/CFS supporting the existence of disease-associated plasma factors to be sensed by iPSCs.METHODS A PRISMA(Preferred Reported Items for Systematic Reviews and Meta-analysis)-based systematic review of the literature was used to select original studies evaluating the metabolite profiles of FM and ME/CFS body fluids.The MeSH terms“metabolomic”or“metabolites”in combination with FM and ME/CFS disease terms were screened against the PubMed database.Only original studies applying omics technologies,published in English,were included.The data obtained were tabulated according to the disease and type of body fluid analyzed.Coincidences across studies were searched and P-values reported by the original studies were gathered to document significant differences found in the disease groups.RESULTS Eighteen previous studies show that some metabolites are commonly altered in ME/CFS and FM body fluids.In vitro cell-based assays have the potential to be developed as screening platforms,providing evidence for the existence of factors in patient body fluids capable of altering morphology,differentiation state and/or growth patterns.Moreover,they can be further developed using approaches aimed at blocking or reversing the effects of specific plasma/serum factors seen in patients.The documented high sensitivity and effective responses of iPSCs to environmental cues suggests that these pluripotent cells could form robust,reproducible reporter systems of metabolic diseases,including ME/CFS and FM.Furthermore,culturing iPSCs,or their mesenchymal stem cell counterparts,in patient-conditioned medium may provide valuable information to predict individual outcomes to stem-cell therapy in the context of precision medicine studies.CONCLUSION This opinion review explains our hypothesis that iPSCs could be developed as a screening platform to provide evidence of a metabolic imbalance in FM and ME/CFS.展开更多
Fatigue cracks that develop in civil infrastructure such as steel bridges due to repetitive loads pose a major threat to structural integrity.Despite being the most common practice for fatigue crack detection,human vi...Fatigue cracks that develop in civil infrastructure such as steel bridges due to repetitive loads pose a major threat to structural integrity.Despite being the most common practice for fatigue crack detection,human visual inspection is known to be labor intensive,time-consuming,and prone to error.In this study,a computer vision-based fatigue crack detection approach using a short video recorded under live loads by a moving consumer-grade camera is presented.The method detects fatigue crack by tracking surface motion and identifies the differential motion pattern caused by opening and closing of the fatigue crack.However,the global motion introduced by a moving camera in the recorded video is typically far greater than the actual motion associated with fatigue crack opening/closing,leading to false detection results.To overcome the challenge,global motion compensation(GMC)techniques are introduced to compensate for camera-induced movement.In particular,hierarchical model-based motion estimation is adopted for 2D videos with simple geometry and a new method is developed by extending the bundled camera paths approach for 3D videos with complex geometry.The proposed methodology is validated using two laboratory test setups for both in-plane and out-of-plane fatigue cracks.The results confirm the importance of motion compensation for both 2D and 3D videos and demonstrate the effectiveness of the proposed GMC methods as well as the subsequent crack detection algorithm.展开更多
Accumulative damage during early stage of fatigue in AISI 321 steel was investigated by eddy current test, atomic force microscopy, X-ray diffraction and transmission electron microscopy. Surface slip, dislocation, an...Accumulative damage during early stage of fatigue in AISI 321 steel was investigated by eddy current test, atomic force microscopy, X-ray diffraction and transmission electron microscopy. Surface slip, dislocation, and strain-induced martensite were determined as the main damage types. Moreover, damage during the fatigue was found to be increased with the increasing fatigue cycles and load amplitude. The contribution of strain-induced martensite to the total eddy current amplitude （V） was enhanced with the increase in its volume fraction. Finally, a linear relationship between V I~, and the height of surface slip was established.展开更多
The morphology of the retained austenite in the carburized case of 20CrNiMo steel and its transformation during fatigue crack propagation through the case were investigated by using X-ray and TEM analysis.In the carbu...The morphology of the retained austenite in the carburized case of 20CrNiMo steel and its transformation during fatigue crack propagation through the case were investigated by using X-ray and TEM analysis.In the carburized case both film and block shaped retained austenite were found.Due to the crystallographic orientation relationship at the interface,the fatigue crack is inclined to pass through the block shaped retained austenite and thereby stim- ulates its strain-induced martensitie transformation.During the process of the fatigue frac- ture,most of the retained austenite structures on the crack path are transformed into the martensite,and the untranaformed parts on the fracture surface remain less than 6%.The transformation of the retained austenite,which is restrieted mainly within the plastic zone,oc- curs only during the proeess of fracture,and is independent of the magnitudes of the external stress,stress ratio and cyclic number.The volume expansion accompanying the transforma- tion creates an additional residual displacement of about 0.44μm on fracture surfaces,which is equivalent to the magnitude of the plasticity-induced residual displacement.The phase transformation induced fatigue crack closure is believed to be an important factor affecting the fatigue crack behaviors in the high carbon laver of the carburized case.展开更多
Owing to the complex environmental conditions, suspension could induce complicated forces on submarine pipelines and even cause vortex-induced vibration, resulting in fatigue damage of pipelines. Through aiming at the...Owing to the complex environmental conditions, suspension could induce complicated forces on submarine pipelines and even cause vortex-induced vibration, resulting in fatigue damage of pipelines. Through aiming at the 28-inch submarine pipeline in the East China Sea, the pipeline was segmented according to the similarity, considering the factors of pipe assembly, typhoon, current, wave and seabed topography. The effects of span length on natural frequency in each section of submarine pipeline were analyzed by finite element model. The maximum safe span length allowed by each pipeline section was verified by fatigue cumulative damage theory, and the fatigue life of each pipeline section were predicted. The results showed that each order natural frequency of the pipeline decreased with the increase of span length. The calculated results of empirical formulas were much smaller than those of the FEM analysis. The increase of the gap between the suspended pipeline and the seabed was beneficial to enhance the fatigue life of the suspended pipeline.展开更多
Objective：To review and assess the effect of single moxibustion for exercise-induced fatigue（EIF）.Methods：Computer-search for 8 medical databases and 5 clinical trail registries were conducted for randomized contr...Objective：To review and assess the effect of single moxibustion for exercise-induced fatigue（EIF）.Methods：Computer-search for 8 medical databases and 5 clinical trail registries were conducted for randomized controlled trials（RCTs）,added with hand-search for 10 Chinese acupuncture-moxibustion journals and additional references.Data from included RCTs were pooled by RevMan5.1.Methodology quality of RCTs was judged by Cochrane Collaboration assessment tool while quality of primary outcomes was evaluated by GRADE3.2.Results：Five RCTs were finally included,all reported in small sample size with high risk of bias.Comparisons on single moxibustion and rest relief（without treatment） were studied.Six outcomes were reported,all favored moxibustion to rest relief for EIF.Primary outcomes showed as rating of perceived exertion（RPE） with mean difference（MD）=-0.49,95%confidence interval（CI）[-0.80,-0.19],800-m race performance with MD=^-2.21,95%CI[-3.57,-0.85],and Harvard Step Index（HSI） with MD=14.75,95%CI[8.35,21.15].Moreover,all primary outcomes as RPE,800-m race performance and HSI were rated low quality.Conclusions：Single moxibustion might be considered effective for EIF.However,due to small samples of included RCTs,high risk of bias among studies and poor quality of primary outcomes and subjects restricted to Chinese athletes only,these results present limitation,and should be taken with caution for practice.More large-size studies with rigorous design are warranted to further test effectiveness of moxibustion for EIF.展开更多
文摘To explore the mechanisms underlying exercise-induced local muscle fatigue in patients with idiopathic Parkinson＇s disease （PD）,we used surface electromyography to record myoelectric signals from the tibialis anterior muscle during isometric contraction-induced fatigue until exhaustion.The results revealed no significant differences between patients with idiopathic PD and healthy controls in maximum voluntary contraction of the tibialis anterior muscle.The basic characteristics of surface electromyography were also similar between the two groups.The duration of isometric contraction at 50% maximum voluntary contraction was shortened in PD patients.In addition,PD patients exhibited a stronger increase in mean square amplitude,but a weaker decrease in median frequency and mean power frequency compared with healthy controls during isometric contraction.The skeletal muscles of PD patients revealed specificity of surface electromyography findings,indicating increased fatigability compared with healthy controls.
文摘With the rapid development of the offshore oil industries, submarine oil / gas pipelines have been widely used. Under the complicated submarine environmental conditions, the dynamic characteristics of pipelines show some new features due to the existence of both internal and external flows. The paper is intended to investigate the vortex-induced vibration of the suspended pipeline span exposed to submarine steady flow. Especially, the effects of the flow inside the pipeline are taken into account. Its influences on the amplitude of pipeline response, and then on the fatigue life, are given in terms of the velocity of the internal flow.
文摘BACKGROUND Fibromyalgia(FM)and myalgic encephalomyelitis/chronic fatigue syndrome(ME/CFS)are devastating metabolic neuroimmune diseases that are difficult to diagnose because of the presence of numerous symptoms and a lack of specific biomarkers.Despite patient heterogeneity linked to patient subgroups and variation in disease severity,anomalies are found in the blood and plasma of these patients when compared with healthy control groups.The seeming specificity of these“plasma factors”,as recently reported by Ron Davis and his group at Stanford University,CA,United States,and observations by our group,have led to the proposal that induced pluripotent stem cells(iPSCs)may be used as metabolic sensors for FM and ME/CFS,a hypothesis that is the basis for this indepth review.AIM To identify metabolic signatures in FM and/or ME/CFS supporting the existence of disease-associated plasma factors to be sensed by iPSCs.METHODS A PRISMA(Preferred Reported Items for Systematic Reviews and Meta-analysis)-based systematic review of the literature was used to select original studies evaluating the metabolite profiles of FM and ME/CFS body fluids.The MeSH terms“metabolomic”or“metabolites”in combination with FM and ME/CFS disease terms were screened against the PubMed database.Only original studies applying omics technologies,published in English,were included.The data obtained were tabulated according to the disease and type of body fluid analyzed.Coincidences across studies were searched and P-values reported by the original studies were gathered to document significant differences found in the disease groups.RESULTS Eighteen previous studies show that some metabolites are commonly altered in ME/CFS and FM body fluids.In vitro cell-based assays have the potential to be developed as screening platforms,providing evidence for the existence of factors in patient body fluids capable of altering morphology,differentiation state and/or growth patterns.Moreover,they can be further developed using approaches aimed at blocking or reversing the effects of specific plasma/serum factors seen in patients.The documented high sensitivity and effective responses of iPSCs to environmental cues suggests that these pluripotent cells could form robust,reproducible reporter systems of metabolic diseases,including ME/CFS and FM.Furthermore,culturing iPSCs,or their mesenchymal stem cell counterparts,in patient-conditioned medium may provide valuable information to predict individual outcomes to stem-cell therapy in the context of precision medicine studies.CONCLUSION This opinion review explains our hypothesis that iPSCs could be developed as a screening platform to provide evidence of a metabolic imbalance in FM and ME/CFS.
基金NCHRP Project,IDEA 223:Fatigue Crack Inspection using Computer Vision and Augmented Reality。
文摘Fatigue cracks that develop in civil infrastructure such as steel bridges due to repetitive loads pose a major threat to structural integrity.Despite being the most common practice for fatigue crack detection,human visual inspection is known to be labor intensive,time-consuming,and prone to error.In this study,a computer vision-based fatigue crack detection approach using a short video recorded under live loads by a moving consumer-grade camera is presented.The method detects fatigue crack by tracking surface motion and identifies the differential motion pattern caused by opening and closing of the fatigue crack.However,the global motion introduced by a moving camera in the recorded video is typically far greater than the actual motion associated with fatigue crack opening/closing,leading to false detection results.To overcome the challenge,global motion compensation(GMC)techniques are introduced to compensate for camera-induced movement.In particular,hierarchical model-based motion estimation is adopted for 2D videos with simple geometry and a new method is developed by extending the bundled camera paths approach for 3D videos with complex geometry.The proposed methodology is validated using two laboratory test setups for both in-plane and out-of-plane fatigue cracks.The results confirm the importance of motion compensation for both 2D and 3D videos and demonstrate the effectiveness of the proposed GMC methods as well as the subsequent crack detection algorithm.
文摘Accumulative damage during early stage of fatigue in AISI 321 steel was investigated by eddy current test, atomic force microscopy, X-ray diffraction and transmission electron microscopy. Surface slip, dislocation, and strain-induced martensite were determined as the main damage types. Moreover, damage during the fatigue was found to be increased with the increasing fatigue cycles and load amplitude. The contribution of strain-induced martensite to the total eddy current amplitude （V） was enhanced with the increase in its volume fraction. Finally, a linear relationship between V I~, and the height of surface slip was established.
文摘The morphology of the retained austenite in the carburized case of 20CrNiMo steel and its transformation during fatigue crack propagation through the case were investigated by using X-ray and TEM analysis.In the carburized case both film and block shaped retained austenite were found.Due to the crystallographic orientation relationship at the interface,the fatigue crack is inclined to pass through the block shaped retained austenite and thereby stim- ulates its strain-induced martensitie transformation.During the process of the fatigue frac- ture,most of the retained austenite structures on the crack path are transformed into the martensite,and the untranaformed parts on the fracture surface remain less than 6%.The transformation of the retained austenite,which is restrieted mainly within the plastic zone,oc- curs only during the proeess of fracture,and is independent of the magnitudes of the external stress,stress ratio and cyclic number.The volume expansion accompanying the transforma- tion creates an additional residual displacement of about 0.44μm on fracture surfaces,which is equivalent to the magnitude of the plasticity-induced residual displacement.The phase transformation induced fatigue crack closure is believed to be an important factor affecting the fatigue crack behaviors in the high carbon laver of the carburized case.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.11802168 and 51575331)project funded by China Postdoctoral Science Foundation(No.2019M661458)
文摘Owing to the complex environmental conditions, suspension could induce complicated forces on submarine pipelines and even cause vortex-induced vibration, resulting in fatigue damage of pipelines. Through aiming at the 28-inch submarine pipeline in the East China Sea, the pipeline was segmented according to the similarity, considering the factors of pipe assembly, typhoon, current, wave and seabed topography. The effects of span length on natural frequency in each section of submarine pipeline were analyzed by finite element model. The maximum safe span length allowed by each pipeline section was verified by fatigue cumulative damage theory, and the fatigue life of each pipeline section were predicted. The results showed that each order natural frequency of the pipeline decreased with the increase of span length. The calculated results of empirical formulas were much smaller than those of the FEM analysis. The increase of the gap between the suspended pipeline and the seabed was beneficial to enhance the fatigue life of the suspended pipeline.
文摘Objective：To review and assess the effect of single moxibustion for exercise-induced fatigue（EIF）.Methods：Computer-search for 8 medical databases and 5 clinical trail registries were conducted for randomized controlled trials（RCTs）,added with hand-search for 10 Chinese acupuncture-moxibustion journals and additional references.Data from included RCTs were pooled by RevMan5.1.Methodology quality of RCTs was judged by Cochrane Collaboration assessment tool while quality of primary outcomes was evaluated by GRADE3.2.Results：Five RCTs were finally included,all reported in small sample size with high risk of bias.Comparisons on single moxibustion and rest relief（without treatment） were studied.Six outcomes were reported,all favored moxibustion to rest relief for EIF.Primary outcomes showed as rating of perceived exertion（RPE） with mean difference（MD）=-0.49,95%confidence interval（CI）[-0.80,-0.19],800-m race performance with MD=^-2.21,95%CI[-3.57,-0.85],and Harvard Step Index（HSI） with MD=14.75,95%CI[8.35,21.15].Moreover,all primary outcomes as RPE,800-m race performance and HSI were rated low quality.Conclusions：Single moxibustion might be considered effective for EIF.However,due to small samples of included RCTs,high risk of bias among studies and poor quality of primary outcomes and subjects restricted to Chinese athletes only,these results present limitation,and should be taken with caution for practice.More large-size studies with rigorous design are warranted to further test effectiveness of moxibustion for EIF.
