Effects of anteriorly-loaded treadmill walking on dynamic gait stability in young adults

BackgroundAnteriorly-loaded walking is common in many occupations and may increase fall risk. Dynamic gait stability, defined by the Feasible Stability Region (FSR) theory, quantifies the kinematic relationship between the body’s center of mass (COM) and base of support (BOS). FSR-based dynamic gait stability has been used to evaluate the fall risk.Research questionHow does front load carriage affect dynamic gait stability, step length, and trunk angle among young adults during treadmill walking?MethodsIn this between-subject design study, 30 healthy young adults were evenly randomized into three load groups (0%, 10%, or 20% of body weight). Participants carried their assigned load while walking on a treadmill at a speed of 1.2 m/s. Body kinematics were collected during treadmill walking. Dynamic gait stability (the primary variable) was calculated for two gait events: touchdown and liftoff. Step length and trunk angle were measured as secondary variables. One-way analysis of variance was conducted to detect any group-related differences for all variables. Post-hoc analysis with Bonferroni correction was performed when main group differences were found.ResultsNo significant differences but medium to large effect sizes were found between groups for dynamic gait stability at touchdown (p = 0.194, η² = 0.114) and liftoff (p = 0.122, η² = 0.139). Trunk angle significantly increased (indicating backward lean) with the front load at touchdown (p < 0.001, η² = 0.648) and liftoff (p < 0.001, η² = 0.543). No significant between-group difference was found related to the step length (p = 0.344, η² = 0.076).SignificanceCarrying a front load during walking significantly alters the trunk orientation and may change the COM-BOS kinematic relationship and, therefore, fall risk. The findings could inform the design of future studies focusing on the impact of anterior load carriage on fall risk during different locomotion.     

Directional tuning of motion-sensitive cells in the anterior superior temporal polysensory area of the macaque

An investigation was made into the directional sensitivity of cells in the macaque anterior superior temporal polysensory region (STPa) to the motion of objects. The cells studied were sensitive to the presence of motion but showed little or no selectivity for the form of the stimulus. Directional tuning was not continuously distributed about all possible directions. The majority of cells were most responsive to motion in a direction within 15° of one of the three cartesian axes (up/down, left/right, towards/away). Tuning to direction varied in sharpness. For most (34/37) cells the angular change in direction required to reduce response to half maximal was between 45 and 70° (for 3/37 cells it was > 90°). The estimates of the directionality (median I _d = 0.97) of STPa cells was similar to that reported for posterior motion processing areas (the middle temporal area, MT, and the medial superior temporal area, MST). The tuning for direction (sharpness, distribution and discrimination) of the motion-sensitive STPa cells were found to be similar to the tuning for perspective view of STPa cells selective for static form of the head and body. On average the STPa responses showed a 100- to 300-ms transient burst of activity followed by a tonic discharge maintained at approximately 20% of the peak firing rate for the duration of stimulation. The responses of motion-sensitive STPa cells occurred at an earlier latency (mean 91 ms) than responses of cells selective for static form (mean 119 ms), but the time course of responses of the two classes of cell were similar in many other respects. The early response latency and directional selectivity indicate that motion sensitivity in STPa cells derives from the dorsal visual pathway via MT/MST. The similarity of tuning for direction and perspective view within STPa may facilitate the integration of motion and form processing within this high-level brain area.     

Causality Between the Amplitude and Frequency of Cardiac Oscillations

Using an information-theoretic approach, causality between the systolic amplitude in blood pressure and the frequency of the heart beat was analyzed. Blood pressure and ECG were noninvasively recorded in young, healthy subjects. Three successive measurements were performed: during spontaneous breathing and during paced respiration—at frequencies both higher and lower than that of spontaneous respiration. We demonstrate that the amplitude and frequency of the cardiac rhythm are synchronized for most of the time. The synchronization is stronger during paced respiration at a frequency lower than that of spontaneous breathing. Episodes where the cardiac frequency was driven by the systolic pressure were also detected during slow, paced respiration.     

Motor cortical activity in a memorized delay task

Summary Two rhesus monkeys were trained to move a handle on a two-dimensional (2D) working surface in directions specified by a light at the plane. They first captured with the handle a light on the center of the plane and then moved the handle in the direction indicated by a peripheral light (cue signal). The signal to move (go signal) was given by turning off the center light. The following tasks were used: (a) In the non-delay task the peripheral light was turned on at the same time as the center light went off. (b) In the memorized delay task the peripheral light stayed on for 300 ms and the center light was turned off 450–750 ms later. Finally, (c) in the non-memorized delay task the peripheral light stayed on continuously whereas the center light went off 750–1050 ms after the peripheral light came on. Recordings in the arm area of the motor cortex (N= 171 cells) showed changes in single cell activity in all tasks. In both delay tasks, the neuronal population vector calculated every 20 ms after the onset of the peripheral light pointed in the direction of the upcoming movement, which was instructed by the cue light. Moreover, the strength of the population signal showed an initial peak shortly after the cue onset in both the memorized and non-memorized delay tasks but it maintained a higher level during the memorized delay period, as compared to the non-memorized task. These results indicate that the motor cortex is involved in encoding and holding in memory directional information concerning a visually cued arm movement and that these processes can be visualized using neuronal population vector analysis.     

Multisensory integration mechanisms in haptic space perception

It has been argued that representations of peripersonal space based on haptic input are systematically distorted by egocentric reference frames. Interestingly, a recent study has shown that noninformative vision (i.e., freely viewing the region above the haptic workspace) improves performance on the so-called haptic parallel-setting task, in which participants are instructed to rotate a test bar until it is parallel to a reference bar. In the present study, we made a start at identifying the different sensory integration mechanisms involved in haptic space perception by distinguishing the possible effects of orienting mechanisms from those of noninformative vision. We found that both the orienting direction of head and eyes and the availability of noninformative vision affect parallel-setting performance and that they do so independently: orienting towards a reference bar facilitated the parallel-setting of a test bar in both no-vision and noninformative vision conditions, and noninformative vision improved performance irrespective of orienting direction. These results suggest the effects of orienting and noninformative vision on haptic space perception to depend on distinct neurocognitive mechanisms, likely to be expressed in different modulations of neural activation in the multimodal parietofrontal network, thought to be concerned with multimodal representations of peripersonal space.     

在超声引导下行宫腔手术的临床分析

目的探讨超声引导下宫腔手术在临床中的应用。方法用超声引导完成较困难的官腔手术,并记录手术时间及出血量。结景手术成功率98．58％,无手术并发症发生。结论超声引导下完成官腔手术,提高了手术的准确性和安全性,避免了手术并发症的发生,尤其是畸形子宫的官腔手术,充分体现了超声引导下手术的优越性。     

轨迹曲面的构造与分析

根据点,线、面的运动轨迹可以形成曲面的原理,应用投影方法将空间轨迹降低为平面上的轨迹,再使平面轨迹按规律运动形成空间曲面,在此基础上获取曲面上点的主曲率和主方向。     

数字化医院建设探讨

探讨数字化医院建设问题.医院数字化是目前国家卫生信息化的重点之一,也是国内医院现代化建设新兴的热点, 数字化医院建设是随着计算机信息技术的进步而逐步兴起和发展的.本文探讨了数字化医院的概念,数字化医院 应具有的功能、数字化医院建设的可行性以及必备条件.论述了数字化医院的应用现状和发展趋势.     

对现代化中医院发展方向的思考

目前,部分中医院处境维艰,有体制因素也有观念问题.中医的传统诊疗手段已不完全适应当前医疗市场的需求,应当充分利用现代科技进行完善提高,而现代科技也将成为中医的有机组成部分.中医院的建设应当遵循医院建设的内在规律,积极发展,改善提高软、硬条件,并根据实际情况积极发展外科,引进、利用现代诊疗手段,走中西医结合之路:中医要领先,西医不落后.     

Retrospective analysis of 616 air-rescue trauma cases related to the practice of extreme sports

IntroductionExtreme sports (ESs) are increasingly popular, and accidents due to ESs sometimes require helicopter emergency medical services (HEMSs). Little is known about their epidemiology, severity, specific injuries and required rescue operations.AimOur aims were to perform an epidemiological analysis, to identify specific injuries and to describe the characteristic of prehospital procedures in ES accidents requiring HEMSs.MethodsThis is a retrospective study, reviewing all rescue missions dedicated to ESs provided by HEMS REGA Lausanne, from 1 January 1998 to 31 December 2008. ES were classified into three categories of practice, according to the type of risk at the time of the fall.ResultsAmong the 616 cases meeting inclusion criteria, 219 (36%) were clearly high-risk ES accidents; 69 (11%) and 328 (53%) were related to potential ES, but with respectively low or indeterminate risk at the time of the fall. In the high-risk ES group, the median age was 32 years and 80% were male. Mortality at 48 h was 11%, almost ten times higher than in the other two groups. The proportion of potentially life-threatening injuries (the National Advisory Committee for Aeronautics (NACA) score ≥ 4) was 39% in the high-risk ES group and 13% in the other two groups. Thirty per cent of the cases in the high-risk ES group presented an Injury Severity Score (ISS) >15, compared with 7% in the other groups. Thoracolumbar vertebral fractures were the most common injuries with 32% of all cases having at least one, involving the T12–L2 junction in 56% of cases. The other most frequent injuries were traumatic brain injuries (16%), rib fractures (9%), pneumothorax (8%) and femoral (7%), cervical (7%), ankle (5%) and pelvic (5%) fractures. Median time on site for rescue teams was higher in the confirmed high-risk ES group, with 50% of prehospital missions including at least one environmental difficulty.ConclusionsHigh-risk ESs led to high-energy accidents, characterized by a large proportion of severe injuries and axial traumas (spine, thorax, pelvis and proximal femur). We identified a considerable percentage of thoracolumbar vertebral fractures, mainly in the T12–L2 junction. HEMSs dedicated to high-risk ESs implied longer and more complex interventions.