In an attempt to study the relationship between sleep postures and sleep parameters assessed by actigraphy, we applied the newly developed Activity Monitoring and Evaluation System (A-MES) and actigraphy at the same t...In an attempt to study the relationship between sleep postures and sleep parameters assessed by actigraphy, we applied the newly developed Activity Monitoring and Evaluation System (A-MES) and actigraphy at the same time to younger and senior Japanese volunteer groups. It was found that sleep postures and diurnal activity determines, to some extent, sleep parameters including activity mean score (AMS), activity index (ACTX), waking episodes (WEP) and sleep fragmentation index (SFX). It was also found that sleep properties are different in younger and senior Japanese. For example, increase in the proportion of time in the supine position resulted in enhancement and deterioration of the sleep in the younger and senior groups, respectively. Furthermore, there were correlations between supine posture and AMS, ACTX, SFX, total minutes scored as awake (TMSA) and WEP obtained by actigraphy in the younger group, but only AMS and ACTX in senior group. In addition, we also assessed sleep parameters by use of questionnaires, and found that objective sleep quality was rather poor but subjective sleep quality was better in the senior group. In the younger group, in contrast, objective sleep quality was better but subjective sleep quality was poor. On the other hand, there was no correlation between sleep parameters assessed by actigraphy and self-report at all. The present study with A-MES and actigraphy provides the first evidence that sleep posture affects sleep quality and is a convenient, inexpensive and home-based method for studying sleep.展开更多
We report recent advances in the experimental and theoretical study of grain size(GS)effects on the thermal and mechanical properties of nanostructured NiTi polycrystalline shape memory alloy(SMA).It is shown that whe...We report recent advances in the experimental and theoretical study of grain size(GS)effects on the thermal and mechanical properties of nanostructured NiTi polycrystalline shape memory alloy(SMA).It is shown that when GS<60 nm,the superelastic stress-strain hysteresis loop area(H)of the polycrystal decreases rapidly with GS and tends to vanish as GS approaches 10 nanometers.At the same time,the temperature dependence of the transition stress also decreases with GS and eventually approaches zero,leading to a wide superelastic temperature window and breakdown of the Clausius-Claperyon relationship.Rate dependence of the stress-strain responses is significantly reduced and the cyclic stability of the material is improved by the nanocrystallization.It is proposed that the emergence of such significant changes in the behavior of the material with GS reduction originate from the large increase in the area-to-volume ratios of the nanometer-thick interfaces(grain boundary and Austenite-Martensite(A-M)interface)in the polycrystal.In particular,with GS reduction,interfacial energy terms will gradually become dominant over the bulk energy of the crystallite,eventually bring fundamental changes in the phase transition responses of the material.Modelling strategy leading to the establishment of quantitative relationships among GS,grain boundary,A-M interfaces and the macroscopic responses of the material are outlined.展开更多
文摘In an attempt to study the relationship between sleep postures and sleep parameters assessed by actigraphy, we applied the newly developed Activity Monitoring and Evaluation System (A-MES) and actigraphy at the same time to younger and senior Japanese volunteer groups. It was found that sleep postures and diurnal activity determines, to some extent, sleep parameters including activity mean score (AMS), activity index (ACTX), waking episodes (WEP) and sleep fragmentation index (SFX). It was also found that sleep properties are different in younger and senior Japanese. For example, increase in the proportion of time in the supine position resulted in enhancement and deterioration of the sleep in the younger and senior groups, respectively. Furthermore, there were correlations between supine posture and AMS, ACTX, SFX, total minutes scored as awake (TMSA) and WEP obtained by actigraphy in the younger group, but only AMS and ACTX in senior group. In addition, we also assessed sleep parameters by use of questionnaires, and found that objective sleep quality was rather poor but subjective sleep quality was better in the senior group. In the younger group, in contrast, objective sleep quality was better but subjective sleep quality was poor. On the other hand, there was no correlation between sleep parameters assessed by actigraphy and self-report at all. The present study with A-MES and actigraphy provides the first evidence that sleep posture affects sleep quality and is a convenient, inexpensive and home-based method for studying sleep.
基金supported by the Hong Kong Research Grant Council(RGC)(Grant No.619113)the National Natural Science Foundation of China(Grant No.11128204)the State Key Lab of Water Resources and Hydropower Engineering of WHU,China
文摘We report recent advances in the experimental and theoretical study of grain size(GS)effects on the thermal and mechanical properties of nanostructured NiTi polycrystalline shape memory alloy(SMA).It is shown that when GS<60 nm,the superelastic stress-strain hysteresis loop area(H)of the polycrystal decreases rapidly with GS and tends to vanish as GS approaches 10 nanometers.At the same time,the temperature dependence of the transition stress also decreases with GS and eventually approaches zero,leading to a wide superelastic temperature window and breakdown of the Clausius-Claperyon relationship.Rate dependence of the stress-strain responses is significantly reduced and the cyclic stability of the material is improved by the nanocrystallization.It is proposed that the emergence of such significant changes in the behavior of the material with GS reduction originate from the large increase in the area-to-volume ratios of the nanometer-thick interfaces(grain boundary and Austenite-Martensite(A-M)interface)in the polycrystal.In particular,with GS reduction,interfacial energy terms will gradually become dominant over the bulk energy of the crystallite,eventually bring fundamental changes in the phase transition responses of the material.Modelling strategy leading to the establishment of quantitative relationships among GS,grain boundary,A-M interfaces and the macroscopic responses of the material are outlined.
