Periodic variations of warp tension during a weaving cycle result in corresponding change of back rest position, and the oscillation of back rest affects the fluctuation of warp yarn in return. A mechanical model of b...Periodic variations of warp tension during a weaving cycle result in corresponding change of back rest position, and the oscillation of back rest affects the fluctuation of warp yarn in return. A mechanical model of back rest system of looms is presented on basis of auto control theory, and the factors affecting the dynamic performance of the back rest are analyzed. In the model, warp yarn is regarded as a viscoelastic medium, and the adjustable parameters and the adjusting range of the back rest system are increased, so the loom's applicability for the fabric's variety is enhanced. Finally, the methods of designing and adjusting the back rest are discussed, and a trend of back rest system development is given.展开更多
Periodic variations of warp tension during a weaving cycle results in corresponding variationsof back rest position.However,the oscillation of back rest,in turn,shows effect on the variation ofdynamic warp tension.As ...Periodic variations of warp tension during a weaving cycle results in corresponding variationsof back rest position.However,the oscillation of back rest,in turn,shows effect on the variation ofdynamic warp tension.As a force transfer medium,warp yarn,with specific dynamic performances,is certainly one of the factors influencing the movement of back rest.In this paper,warp yarn istreated as a viscoelastic medium in studying the dynamic behaviours of back rest.A mathematicalmodel of a back rest system is developed based on the automatic control theory.Several factors arelisted,which show influences on the performances of the back rest system.Analytical work is car-ried out to identify the effects on the frequency response of the back rest systen resulting from vari-ations of such parameters as the modulus of elasticity,of both fast-elastic and slow-elasticdeformations,and viscosity coefficient.展开更多
Functional magnetic resonance imaging studies have shown that the insular cortex has a signif- icant role in pain identification and information integration, while the default mode network is associated with cognitive...Functional magnetic resonance imaging studies have shown that the insular cortex has a signif- icant role in pain identification and information integration, while the default mode network is associated with cognitive and memory-related aspects of pain perception. However, changes in the functional connectivity between the defauk mode network and insula during pain remain unclear. This study used 3.0 T functional magnetic resonance imaging scans in 12 healthy sub- jects aged 24.8 ± 3.3 years to compare the differences in the functional activity and connectivity of the insula and default mode network between the baseline and pain condition induced by intramuscular injection of hypertonic saline. Compared with the baseline, the insula was more functionally connected with the medial prefrontal and lateral temporal cortices, whereas there was lower connectivity with the posterior cingulate cortex, precuneus and inferior parietal lobule in the pain condition. In addition, compared with baseline, the anterior cingulate cortex exhibited greater connectivity with the posterior insula, but lower connectivity with the anterior insula, during the pain condition. These data indicate that experimental low back pain led to dysfunction in the connectivity between the insula and default mode network resulting from an impairment of the regions of the brain related to cognition and emotion, suggesting the impor- tance of the interaction between these regions in pain processing.展开更多
目的采用静息态功能磁共振成像(resting state functional magnetic resonance imaging,rs⁃fMRI)技术探究电针治疗原发性骨质疏松症腰背痛的临床疗效和中枢机制。方法纳入25例原发性骨质疏松症腰背痛患者作为观察组,招募性别、年龄相匹...目的采用静息态功能磁共振成像(resting state functional magnetic resonance imaging,rs⁃fMRI)技术探究电针治疗原发性骨质疏松症腰背痛的临床疗效和中枢机制。方法纳入25例原发性骨质疏松症腰背痛患者作为观察组,招募性别、年龄相匹配的20名健康志愿者作为健康对照组。观察组予电针治疗,每周3次,共治疗4周。比较治疗前后视觉模拟评分(visual analogue scale,VAS)、简式McGill疼痛问卷(short⁃form of McGill pain questionnaire,SF⁃MPQ)、腰椎功能障碍指数(oswestry disability index,ODI)。观察组治疗前后及健康对照组入组时均接受rs⁃fMRI扫描,比较观察组与健康受试者脑功能活动局部一致性值(regional homogeneity,ReHo)的差异;观察电针治疗前后观察组ReHo值的变化;并将ReHo变化值与VAS改善值进行相关性分析。结果与治疗前比较,观察组治疗后VAS、SF⁃MPQ、ODI评分降低(P<0.01)。观察组治疗前与健康对照组相比,共有7个脑区ReHo值发生改变,降低的脑区包括右侧楔前叶、右侧额下回、右侧角回、左侧角回、枕下小叶,增强的脑区有左侧颞上回和右侧脑干。与治疗前比较,治疗后上述7个脑区的ReHo值中,左侧颞上回、右侧脑干明显下降(P<0.05),右侧楔前叶和右侧额下回明显增强(P<0.05)。相关性分析显示,治疗前后右侧楔前叶ReHo变化值与VAS改善差值呈负相关(r=-0.548,P=0.015)。结论电针治疗可改善原发性骨质疏松症患者腰背部疼痛,右侧楔前叶脑区自发性脑活动改变可能是电针起效的中枢机制之一。展开更多
文摘Periodic variations of warp tension during a weaving cycle result in corresponding change of back rest position, and the oscillation of back rest affects the fluctuation of warp yarn in return. A mechanical model of back rest system of looms is presented on basis of auto control theory, and the factors affecting the dynamic performance of the back rest are analyzed. In the model, warp yarn is regarded as a viscoelastic medium, and the adjustable parameters and the adjusting range of the back rest system are increased, so the loom's applicability for the fabric's variety is enhanced. Finally, the methods of designing and adjusting the back rest are discussed, and a trend of back rest system development is given.
文摘Periodic variations of warp tension during a weaving cycle results in corresponding variationsof back rest position.However,the oscillation of back rest,in turn,shows effect on the variation ofdynamic warp tension.As a force transfer medium,warp yarn,with specific dynamic performances,is certainly one of the factors influencing the movement of back rest.In this paper,warp yarn istreated as a viscoelastic medium in studying the dynamic behaviours of back rest.A mathematicalmodel of a back rest system is developed based on the automatic control theory.Several factors arelisted,which show influences on the performances of the back rest system.Analytical work is car-ried out to identify the effects on the frequency response of the back rest systen resulting from vari-ations of such parameters as the modulus of elasticity,of both fast-elastic and slow-elasticdeformations,and viscosity coefficient.
基金supported by the Science and Technology Foundation of Guangdong Province of China,No.2012B031800305
文摘Functional magnetic resonance imaging studies have shown that the insular cortex has a signif- icant role in pain identification and information integration, while the default mode network is associated with cognitive and memory-related aspects of pain perception. However, changes in the functional connectivity between the defauk mode network and insula during pain remain unclear. This study used 3.0 T functional magnetic resonance imaging scans in 12 healthy sub- jects aged 24.8 ± 3.3 years to compare the differences in the functional activity and connectivity of the insula and default mode network between the baseline and pain condition induced by intramuscular injection of hypertonic saline. Compared with the baseline, the insula was more functionally connected with the medial prefrontal and lateral temporal cortices, whereas there was lower connectivity with the posterior cingulate cortex, precuneus and inferior parietal lobule in the pain condition. In addition, compared with baseline, the anterior cingulate cortex exhibited greater connectivity with the posterior insula, but lower connectivity with the anterior insula, during the pain condition. These data indicate that experimental low back pain led to dysfunction in the connectivity between the insula and default mode network resulting from an impairment of the regions of the brain related to cognition and emotion, suggesting the impor- tance of the interaction between these regions in pain processing.
文摘目的采用静息态功能磁共振成像(resting state functional magnetic resonance imaging,rs⁃fMRI)技术探究电针治疗原发性骨质疏松症腰背痛的临床疗效和中枢机制。方法纳入25例原发性骨质疏松症腰背痛患者作为观察组,招募性别、年龄相匹配的20名健康志愿者作为健康对照组。观察组予电针治疗,每周3次,共治疗4周。比较治疗前后视觉模拟评分(visual analogue scale,VAS)、简式McGill疼痛问卷(short⁃form of McGill pain questionnaire,SF⁃MPQ)、腰椎功能障碍指数(oswestry disability index,ODI)。观察组治疗前后及健康对照组入组时均接受rs⁃fMRI扫描,比较观察组与健康受试者脑功能活动局部一致性值(regional homogeneity,ReHo)的差异;观察电针治疗前后观察组ReHo值的变化;并将ReHo变化值与VAS改善值进行相关性分析。结果与治疗前比较,观察组治疗后VAS、SF⁃MPQ、ODI评分降低(P<0.01)。观察组治疗前与健康对照组相比,共有7个脑区ReHo值发生改变,降低的脑区包括右侧楔前叶、右侧额下回、右侧角回、左侧角回、枕下小叶,增强的脑区有左侧颞上回和右侧脑干。与治疗前比较,治疗后上述7个脑区的ReHo值中,左侧颞上回、右侧脑干明显下降(P<0.05),右侧楔前叶和右侧额下回明显增强(P<0.05)。相关性分析显示,治疗前后右侧楔前叶ReHo变化值与VAS改善差值呈负相关(r=-0.548,P=0.015)。结论电针治疗可改善原发性骨质疏松症患者腰背部疼痛,右侧楔前叶脑区自发性脑活动改变可能是电针起效的中枢机制之一。
