To improve the accuracy of dynamic stability analysis of gait across obstacles. The conventional kinematics parameters and temporal dynamic parameters were calculated and compared. The dynamic stability control ability of the young group, the old group, and the fall group was analyzed when crossing obstacles of random height. The kinematic parameters can express the difference in dynamic stability caused by aging, and the temporal dynamic stability parameters can express the subtle differences between the fall group and the elderly group, and the two-dimensional ROSa Shannon entropy is more sensitive. This paper analyzes the performance of different parameters in analyzing the difference in dynamic stability when crossing obstacles of random height, which improves the accuracy of the dynamic stability analysis method for crossing obstacles

To compare the differences between the single-time dynamic stability analysis parameters and the time series dynamic stability parameters in distinguishing the dynamic stability of the elderly's gait across obstacles. The conventional kinematics parameters, such as toe-obstacle distance, heel-obstacle distance, and toe-obstacle clearance, the single temporal parameters of dynamic stability, two-dimensional region of velocity stability, were calculated, the Fréchet distance method was introduced to calculate the temporal parameters of dynamic stability. There was no statistically significant difference between the elderly group and the fall group in the kinematics parameters. The temporal parameters of dynamic stability not only reflected the decline of dynamic stability caused by aging and the occurrence of tripping history but also could significantly distinguish the differences between the elderly group and the fall group. This study improves the accuracy of the dynamic stability of the single limb support phase, which can provide a reference for the assessment and intervention of the fall risk of the elderly.

The purpose of this study was to investigate the environment risk factors of fall during the past year in community-dwelling elderly in Beijing. A random sampling combined with quota sampling questionnaire survey was conducted to collect data in 9 districts in Beijing. A total of 1509 persons aged 60+ were surveyed. Information related to demographic, home security environment situation, and fall consequence in the past year. It was found that 416 elderly had falling 525 times respectively, with the incidence rate of single fall as 27.57%, slip (39.42%) and trip(30.05%) are the most high frequency. In the home environment, fall 356 times, the ground and corridor, bathroom installation will significantly affect the occurrence of falls. Demographic characteristics such as gender, pre-retirement occupation, physical health self-reporting, and whether or not to continue working were also significantly different and were included in the fall regression equation. The incidence of falls among the elderly in communities in Beijing is relatively high, and the incidence of falls is related to environmental factors at home, measures should be taken to intervene.

To calculate the threshold of obstacle height that could ensure the safe crossing of the elderly. The conventional kinematics parameters, TO moment, and temporal dynamic parameters were involved. The dynamic stability parameters of the young group, the elderly group, and the fall group were calculated under the 5m-25cm obstacle gait. Both kinematic and dynamic stability parameters can reflect the changes in dynamic stability with aging. Still, only the temporal dynamic stability parameter can significantly distinguish the detailed differences between the elderly group and the fall group, and this difference occurred only when the height of the obstacle reached 20cm. This study calculates the height threshold for the elderly to safely cross obstacles, which can guide the aging adaptation of related facilities.

Background: Falls are a major health problem for older adults, accounting for about one-third to one-half of them. It is of great significance to study the gait stability of the elderly over obstacles for the prevention of falls. Objective: The dynamic stability parameters, which can distinguish the difference between the fall and control groups, were analyzed and extracted under single obstacle crossing gait. Methods: The subjects were included in the youth health group, the elderly health group, and the elderly fall group. A 3D motion capture system was used to collect the subject’s motion data. The conventional kinematic parameters such as toe-obstacle distance, heel-obstacle distance, toe-obstacle clearance, the center of mass velocity and acceleration, as well as the dynamic stability parameters in the sagittal plane, coronal plane, and two-dimensional velocity stability domain were calculated when crossing 20cm single obstacle gait. Results: The toe-obstacle distance and clearance gradually decreased with the increase of age and the occurrence of fall history, but there was no statistically significant difference between groups. In the sagittal plane and two-dimensional plane, the center of mass acceleration of the elderly fall group was significantly slower. Compared with the young healthy group and the elderly healthy group, the elderly fall group placed their center of mass in the front position at the moment of toe-off, resulting in their center of the mass position-velocity combination being within the speed stability boundary and showing a greater stability margin. Significance: The center of mass dynamic stability parameter can be used to quantitatively describe the difference in dynamic stability during walking between the young healthy group, the old healthy group, and the old fall group. Quantitative studies show that the dynamic stability of the subjects gradually decreases with the increase of age or the influence of previous fall history. Compared with sagittal plane or coronal plane parameters, two-dimensional parameters can more sensitively reflect the difference in dynamic stability between the fall group and the elderly group, which may be related to its more comprehensive reflection of human gait information, thus improving the accuracy of walking gait dynamic stability analysis.

To analyze the differences in dynamic stability between different populations in flat walking and obstacle-crossing gait. Two-dimensional Center of Mass (COM) velocity peak, two-dimensional COM acceleration peak, two-dimensional Region of Velocity Stability (ROS) velocity at Toe-off, two-dimensional ROS velocity Frechet distance, and two-dimensional ROS acceleration Shannon entropy were involved. The dynamic stability parameters of the young group, the elderly group, and the faller group were calculated on flat ground and over 15cm obstacles gait. A decrease in dynamic stability when crossing obstacles with increasing age or the effect of a trip history. Moreover, the sensitivity of dynamic stability parameters is different for different conditions. This paper analyzes the differences in dynamic stability between different groups of subjects during flat walking and across obstacles, which can provide a reference for the prevention of tripping.

男性,69岁.2007年(53岁)体检时眼压21 mmHg,眼底照相示双眼视杯较大但视网膜神经纤维层(RNLF)正常(左上图为右眼,左下图为左眼)而可疑青光眼.随后多次随诊,结论仍为可疑青光眼.2023年1月再次随诊,视力右眼0.8,左眼1.0,眼压右眼18 mmHg,左眼 19 mmHg.

Falling is an important public health issue, and predicting the fall risk can reduce the incidence of injury events in the elderly. However, most of the existing studies may have additional human and financial costs for community workers and doctors. Therefore, it is socially important to identify elderly people who are at high fall risk through a reasonable and cost-effective method. We evaluated the potential of multifractal, machine learning algorithms to identify the elderly at high fall risk. We developed a 42-point calibration model of the human body and recorded the three-dimensional coordinate datasets. The stability of the motion trajectory is calculated by the multifractal algorithm and used as an input dimension to compare the performance of the six classifiers. The results showed that the instability of the faller group was significantly greater than that of the no-faller group in the male and female cohorts (p < 0.005), and the Gradient Boosting Decision Tree classifier showed the best performance. The findings could help elderly people at high fall risk to identify individualized risk factors and facilitate tailored fall interventions.

为提高应急志愿宣教水平,建立提高应急志愿宣教活动满意概率的规划路径,通过构建应急志愿服务活动流程图,以贝叶斯网络为基础,分析满意概率较高的活动规划,并估计规划因素权重.在224条规划路径中,有66条路径的活动满意概率为100％,满意概率92％以上的活动规划路径仅占32％,宣传方式、活动类型、活动内容、活动结束4个因素具有近似的分配权重.应急志愿组织开展宣教活动的效果差异性较大,通过有效规划,可减少无效投入,提高受众满意率.

In order to improve the ability of community governance and reduce the occurrence of accidents, based on the entropy and self-organization theory, this paper first analyzes the influencing factors of community resilience, analyzes the process of emergency and the key factors of response from the change of entropy value of community security system, constructs the mathematical expression of community resilience and entropy value, extracts the evolution law of community resilience, and then constructs the decision theory of building entropy effect and improving community resilience from the perspective of input-output benefit. The results show that the community resilience is positively correlated with the absolute value of negative entropy; the community resilience is negatively correlated with the absolute value of positive entropy; the system resilience can be improved by allocating the limited degree and quantity value according to the importance of the impact on the correlation of each subsystem in the community system.

目的 跌倒是导致老年人意外死亡的第二大因素,通过快捷的实验方法和步态参数来区分老年人中的易跌倒人群,加以精准干预,可以显著降低老年人跌倒发生概率,具有重要的社会意义.方法 招募54名不同跌倒史老年人参与增强的起立行走实验(Enhanced-TUG),使用三维运动捕捉系统收集三维时空数据.计算转身前、转身和转身后的整个过程中的三维步态数据加速度和速度值,并通过离散傅立叶变换将其转换为时域和频域数据,以确定不同行走阶段和不同跌倒史次数人群的步态特征差异.结果 随着跌倒次数的增加,老年人步速逐渐降低;跌倒组老年人转身速度较慢;跌倒组老年人加速度与速度信号的幅值四分位数、均值大于非跌倒组,低频高幅信号段为跌倒组的主要特征.结论 利用增强的起立行走实验结合简单的时频步态参数分析可快速的对老年人步态稳定性进行区分,识别易跌倒老年人群.

Urban community, as the basic unit of urban operation, is the direct recipient of all kinds of urban disasters. Strengthening emergency management and emergency capacity construction of urban community can effectively improve the level of urban governance, and is also the basic guarantee of building a harmonious society. This paper discusses the importance of urban community emergency management mechanism construction, and through the analysis of the characteristics of urban community disasters, it is concluded that urban community disasters have suddenness, emergency, diffusion, harm and universality of influence. In view of the problems existing in the urban community emergency management, put forward to establish a special community emergency management and coordination agency, perfecting the multi-agent collaborative management, establishing and perfecting the community emergency plan system, perfecting the community autonomous rule, giving full play to the advantages of modern science and technology, a total of five urban community disaster risk emergency management mechanism, to enhance the level of urban community emergency and thus to ensure the safety of the whole city.

More and more hybrid brain-computer interfaces (BCI) supplement traditional single-modality BCI in practical applications. Combinations based on steady-state visual evoked potential (SSVEP) and electromyography (EMG) are the widely used hybrid BCIs. The EMG of jaw clench is commonly used together with SSVEP. This article explored the interference with SSVEP from occipital electrodes by the jaw clench-related EMG so that SSVEP with specific frequency can be identified even during occlusal movements. The experiment was divided into three sets base on the jaw clench patterns (no clenches, chew, and long clench). In each set, the subjects used the same visual stimuli, which were realized by the three flashing targets at different frequencies (6.2Hz, 9.8Hz, and 14.6Hz). After collecting the SSVEP at 4 sites in the occipital region, the SSVEP response spectrum of each stimulus was observed under the three jaw clench patterns. Then, the SSVEP signal was identified by the canonical correlation analysis method for accuracy statistics. Spectrum responses showed that the interference of the jaw clench EMG on SSVEP could be avoided when the stimulation frequency is lower than 20Hz. SSVEP could be identified based on the frequency domain characteristics of these signals. During steady-state visual stimulation with jaw clenches, the recognition rate of SSVEP was still high (no clenches: 100.0%, chew: 94.7%, and long clench: 100.0%). Through reasonable frequency selecting and signal processing, the influence of the jaw clench movement on the SSVEP could be reduced and a high recognition accuracy could be achieved, even the jaw clench actions and the SSVEP stimulation occur simultaneously.

As the most influential sports event in the world, there will be many athletes and spectators from all over the world during the Olympic Games. However, the continuing severe global COVID-19 situation has a significant impact on the smooth hosting of the 2022 Beijing Winter Olympics Games (hereinafter referred to as the “Beijing Winter Olympics”). Based on above, this paper analyzed the impact of the global COVID-19 and expounded the six risks of Beijing Winter Olympic Games. Finally, it provided corresponding suggestions and countermeasures of the preparatory work transition for the change of running mode. It is expected to provide theoretical reference and decision-making support for the Beijing Winter Olympic Games to prevent and control of the COVID-19 emergency risk.

为获取乘客在地铁突发事件下对典型疏散行为的认知情况,以北京地区为例开展问卷调查,最终回收有效问卷397份.统计结果显示:乘客对地铁应急疏散知识存在一定程度的了解,但大多数乘客缺乏应急疏散经验和演练经历,在疏散措施选择方面与乘客年龄、学历存在相关性;超九成乘客会因地铁突发事件产生恐慌心理,且极易出现不听指挥、从众等不理性反应.在此基础上,对7种疏散行为下设的16项变量进行Spearman相关分析,发现相关系数在-0.15～0.39之间,大部分恐慌行为、自主疏散行为、从众行为、排他行为类指标相关性偏高,互助行为、返回行为、习惯行为类指标相关性较弱.进一步分析发现,不听指挥、排挤前方乘客、不帮助不适乘客、盲目跟随、失去判断、出口扎堆、通道从众、自主疏散8项变量间的相关系数在0.62～0.74之间,存在较强的正相关关系,且大多为不理性疏散行为.

Disaster preparedness is crucial for providing an effective response to, and reducing the possible impacts of, disasters. Although volunteers' participation plays an important role in disaster preparedness, their actual participation in disaster preparedness activities is still low. To find ways to encourage more volunteers to participate, this study analyzed the social background and organizational and attitudinal factors affecting the volunteers' willingness to participate. Questionnaires were distributed to 990 registered disaster volunteers across Beijing and the data were analyzed using linear regression models. Results revealed a weak willingness to participate in disaster preparedness. Only 28.08% of the respondents indicated that they were "very ready" to participate in voluntary disaster preparedness, and 14.65% showed "a little bit" of interest. The following was concluded: (1) Disaster volunteers' social background variables were related to their willingness to participate in disaster preparedness. Compared to male volunteers, female volunteers were more willing to participate. Chinese Communist Party members were more willing to participate than non-members. (2) Providing accidental life insurance for the volunteers had a positive effect on their willingness to participate in disaster preparedness. Provision of more training had a negative effect on the volunteers' willingness to participate, indicating a low quality of training. (3) Organizational identification was positively related to the volunteers' willingness to participate. According to these results, we suggest that volunteer organizations should improve their standards and procedures for disaster volunteer recruitment and selection, and gain a deeper understanding of the needs of the disaster volunteers in order to better motivate them to participate.

作为城市经济发展重要依托的综合商务楼宇在运营中仍旧存在安全风险.基于此,本文运用专家调查法,结合整体分析与比对分析,研究了综合商务楼宇安全管理现状中存在的问题,进而提出综合商务楼宇应进一步完善安全管理工作制度,加强风险监管工作力度,创新高品质安全管理方式及倡导楼宇安全管理行业化等措施,以期为楼宇从源头上进行安全管理提供科学方法和应用参考.

Objective: To define a two-dimensional (2-D) region of stability derived by center of mass (COM) velocity, and to assess the dynamic walking stability with COM position and velocity. Methods: The 2-D base of support (BOS) was determined by the intersection between the vector of the 2-D COM velocity and the envelope of the foot pressure. The region of stability for velocity (ROSv) in 2-D were determined using normalized COM position and velocity at toe off (TO). In order to exam the utility of this new parameter, fourteen elderly females with and without history of falls participated into a walking experiment. Results: The results showed that the 2-D ROSv could distinguish the coordinates difference between two groups much better than 1-D form in antero-posterior. COM position of elderly fallers demonstrated significant closer to the foot supporting boundary than that of healthy elderly adults at TO. Conclusion: The parameter of 2-D ROSv could differentiate among dynamic stability for healthy elderly adults and fallers. The results of walking experiment revealed elderly fallers tend to walk more conservatively compared to healthy subjects, to relieve the pressure of controlling their momentum.

The research scope of safety culture development in urban community is urban community. The purpose of this study is to further improve the safety atmosphere of urban communities, reduce the safety risk of urban community, and ensure the harmonious and happy life of residents. This paper discusses the content and mode of the safety culture development in urban community, and puts forward the promotion mechanism of the safety culture development in urban community. This study is of great significance to enhance the ability of urban community security and risk prevention and control, enhance the sense of access, happiness and security of residents, and ensure the safety, harmony and sustainable development of the city.