Ground substrates classification and adaptive walking through interaction dynamics for legged robots

Adaptive locomotion in different types of surfaces is of critical importance for legged robots.The knowledge of various ground substrates,especially some geological properties,plays an essential role in ensuring the legged robots'safety.In this paper,the interaction between the robots and the environments is investigated through interaction dynamics with the closed-loop system model,the compliant contact model,and the friction model,which unveil the influence of environment's geological characteristics for legged robots'locomotion.The proposed method to classify substrates is based on the interaction dynamics and the sensory-motor coordination.The foot contact forces,joint position errors,and joint motor currents,which reflect body dynamics,are measured as the sensing variables.We train and classify the features extracted from the raw data with a multilevel weighted k-Nearest Neighbor(kNN) algorithm.According to the interaction dynamics,the strategy of adaptive walking is developed by adjusting the touchdown angles and foot trajectories while lifting up and dropping down the foot.Experiments are conducted on five different substrates with quadruped robot FROG-I.The comparison with other classification methods and adaptive walking between different substrates demonstrate the effectiveness of our approach.

Surgical intervention combined with weight-bearing walking training promotes recovery in patients with chronic spinal cord injury:a randomized controlled study

For patients with chronic spinal cord injury,the co nventional treatment is rehabilitation and treatment of spinal cord injury complications such as urinary tract infection,pressure sores,osteoporosis,and deep vein thrombosis.Surgery is rarely perfo rmed on spinal co rd injury in the chronic phase,and few treatments have been proven effective in chronic spinal cord injury patients.Development of effective therapies fo r chronic spinal co rd injury patients is needed.We conducted a randomized controlled clinical trial in patients with chronic complete thoracic spinal co rd injury to compare intensive rehabilitation(weight-bearing walking training)alone with surgical intervention plus intensive rehabilitation.This clinical trial was registered at ClinicalTrials.gov(NCT02663310).The goal of surgical intervention was spinal cord detethering,restoration of cerebrospinal fluid flow,and elimination of residual spinal cord compression.We found that surgical intervention plus weight-bearing walking training was associated with a higher incidence of American Spinal Injury Association Impairment Scale improvement,reduced spasticity,and more rapid bowel and bladder functional recovery than weight-bearing walking training alone.Overall,the surgical procedures and intensive rehabilitation were safe.American Spinal Injury Association Impairment Scale improvement was more common in T7-T11 injuries than in T2-T6 injuries.Surgery combined with rehabilitation appears to have a role in treatment of chronic spinal cord injury patients.

Effect of Brisk Walking on Self-Care Agency or Care Dependency among Colorectal Cancer Patients with Permanent Stoma

Objective:The purpose of this study was to determine the effectiveness of brisk walking as an intervention for self-care agency and care dependency in patients with permanent colorectal cancer stoma.Method:This study adopted a quasi-experimental research design,specifically a non-equivalent control group pre-test and post-test design.Utilizing the Exercise of Self-Care Agency Scale(ESCA)and Care Dependency Scale(CDS),a survey was administered to 64 patients from a hospital in Shandong Province.The statistical methods used for analyzing data included frequency,mean,standard deviation(SD),independent t-test,P-value calculation,and dependent t-test.Result:After two months of a brisk walking exercise program,participants in the experimental group had a higher level of self-care agency than before the experiment(P<0.05),and their level of care dependency was significantly reduced(P<0.05).Participants in the control group also showed higher levels of self-care agency(P<0.05)and lower levels of care dependency(P<0.05)after two months compared to their levels before the two months.Conclusion:The brisk walking program had a positive impact on patients’self-care agency and reduced their care dependency.

A Wire-Driven Series Elastic Mechanism Based on Ultrasonic Motor for Walking Assistive System

In order to improve the elderly people's quality of life,supporting their walking behaviors is a promising technology.Therefore,based on one ultrasonic motor,a wire-driven series elastic mechanism for walking assistive system is proposed and investigated in this research.In contrast to tradition,it innovatively utilizes an ultrasonic motor and a wire-driven series elastic mechanism to achieve superior system performances in aspects of simple structure,high torque/weight ratio,quiet operation,quick response,favorable electromagnetic compatibility,strong shock resistance,better safety,and accurately stable force control.The proposed device is mainly composed of an ultrasonic motor,a linear spring,a steel wire,four pulleys and one rotating part.To overcome the ultrasonic motor's insufficient output torque,a steel wire and pulleys are smartly combined to directly magnify the torque instead of using a conventional gear reducer.Among the pulleys,there is one tailored pulley playing an important role to keep the reduction ratio as 4.5 constantly.Meanwhile,the prototype is manufactured and its actual performance is verified by experimental results.In a one-second operating cycle,it only takes 86 ms for this mechanism to output an assistive torque of 1.6 N·m.At this torque,the ultrasonic motor's speed is around 4.1 rad/s.Moreover,experiments with different operation periods have been conducted for different application scenarios.This study provides a useful idea for the application of ultrasonic motor in walking assistance system.

Theoretical and Numerical Studies on the Coupling Deformation of Global Lateral Buckling and Walking of Submarine Pipeline

Buckling initiation devices/techniques,including sleepers,distributed buoyancy,snake lay,and residual curvature method(RCM),have recently been widely applied in engineering.These initiated buckles may induce a long pipeline to transform into multiple short pipeline segments,which promote the occurrence of pipeline walking.Thus,a pipeline,which is designed to buckle laterally,may laterally and axially displace over time when subjected to repeated heating and cooling cycles.This study aims to reveal the coupling mechanism of pipeline walking and global lateral buckling.First,an analytic solution is proposed to estimate the walking of pipeline segments between two adjacent buckles.Then,the sensitivity of this method to heating and cooling cycles is analyzed.Results show the applicability of the proposed walking analytical solution of buckling pipelines.Subsequently,an influence analysis of walking on global buckling,including the capacity of buckling initiation,buckling amplitude,buckling mode,and failure assessment of the buckling pipeline,is performed.The results reveal that the effect of walking on the buckling axial force is negligible.However,pipeline walking will aggravate the asymmetry of the pipeline buckling and the failure parameters of the pipeline during the post-buckling.

A new passive transfemoral prosthesis mechanism based on 3R36 knee and ESAR foot providing walking and squatting

Researchers have proposed various linkage mechanisms to connect knee and ankle joints for above-knee prosthe-ses,but most of them only offer natural walking.However,studies have shown that people assume a squatting posture during daily activities.This paper introduces a novel mechanism that connects the knee joint with the foot-ankle joint to enable both squatting and walking.The prosthetic knee used is the well-known 3R36,while the energy storing and return(ESAR)prosthetic foot is used for the ankle-foot joint.To coordinate knee and ankle joint movements,a six-bar linkage mechanism structure is proposed.Simulation results demonstrate that the proposed modular transfemoral prosthesis accurately mimics the motion patterns of a natural human leg during walking and squatting.For instance,the prosthesis allows a total knee flexion of more than 140°during squatting.The new prosthesis design also incorporates energy-storing mechanisms to reduce energy expenditure during walking for amputees.

城市漫步体验中的移动端导识系统设计探索

目的城市漫步活动作为一种新型的旅游活动正在受到越来越多人的关注和参与,导识系统在旅游活动中非常重要,而应用在传统旅游活动中的导识系统并不适用于城市漫步体验,应当针对城市漫步活动的特征,构建适用于城市漫步的导识系统设计策略。方法基于城市漫步的特点和游客的体验需求,结合普适性的城市导识系统设计策略,从路线、标识、信息、体验四个方面得出适用于城市漫步的导识系统设计策略,并应用在城市漫步活动“悠栽逛中轴”中。结论基于移动端的城市漫步导识系统的功能不仅限于协助到达目的地,更应当提供丰富的文化信息和趣味性体验,让游客充分体验到漫步的乐趣和城市文化魅力。

ON THE EMPTY BALLS OF A CRITICAL OR SUBCRITICAL BRANCHING RANDOM WALK

Let{Z_(n)}_(n)≥0 be a critical or subcritical d-dimensional branching random walk started from a Poisson random measure whose intensity measure is the Lebesugue measure onℝ^(d).Denote by R_(n):=sup{u>0:Z_(n)({x∈ℝ^(d):∣x∣<u})=0}the radius of the largest empty ball centered at the origin of Zn.In this work,we prove that after suitable renormalization,Rn converges in law to some non-degenerate distribution as n→∈.Furthermore,our work shows that the renormalization scales depend on the offspring law and the dimension of the branching random walk.This completes the results of Révész[13]for the critical binary branching Wiener process.

Spatial search weighting information contained in cell velocity distribution

Cell migration plays a significant role in physiological and pathological processes.Understanding the characteristics of cell movement is crucial for comprehending biological processes such as cell functionality,cell migration,and cell–cell interactions.One of the fundamental characteristics of cell movement is the specific distribution of cell speed,containing valuable information that still requires comprehensive understanding.This article investigates the distribution of mean velocities along cell trajectories,with a focus on optimizing the efficiency of cell food search in the context of the entire colony.We confirm that the specific velocity distribution in the experiments corresponds to an optimal search efficiency when spatial weighting is considered.The simulation results indicate that the distribution of average velocity does not align with the optimal search efficiency when employing average spatial weighting.However,when considering the distribution of central spatial weighting,the specific velocity distribution in the experiment is shown to correspond to the optimal search efficiency.Our simulations reveal that for any given distribution of average velocity,a specific central spatial weighting can be identified among the possible central spatial weighting that aligns with the optimal search strategy.Additionally,our work presents a method for determining the spatial weights embedded in the velocity distribution of cell movement.Our results have provided new avenues for further investigation of significant topics,such as relationship between cell behavior and environmental conditions throughout their evolutionary history,and how cells achieve collective cooperation through cell-cell communication.

Characteristics of cell motility during cell collision

Quantitative examination of cellular motion and intercellullar interactions possesses substantial relevance for both biology and medicine.However,the effects of intercellular interactions during cellular locomotion remain under-explored in experimental research.As such,this study seeks to bridge this research gap,adopting Dictyostelium discoideum(Dicty)cells as a paradigm to investigate variations in cellular motion during reciprocal collisions.We aim to attain a comprehensive understanding of how cell interactions influence cell motion.By observing and processing the motion trajectories of colliding cells under diverse chemical environments,we calculated the diffusion coefficient(D)and the persistence time(τ),using mean square displacement.Our analysis of the relationship dynamics between D andτprior to the collisions reveals intricate and non-monotonic alterations in cell movements during collisions.By quantitatively scrutinizing theτtrend,we were able to categorize the cellular responses to interactions under different conditions.Importantly,we ascertained that the effect of cell interactions during collisions in Dicty cells emulates a classical sigmoid function.This discovery suggests that cellular responses might comply with a pattern akin to the Weber–Fechner law.

Mobility edges and localization characteristics in one-dimensional quasiperiodic quantum walk

We construct a one-dimensional quasiperiodic quantum walk to investigate the localization–delocalization transition.The inverse participation ratio and Lyapunov exponent are employed as two indexes to determine the mobility edge, a critical energy to distinguish the energy regions of extended and localized states. The analytical solution of mobility edge is obtained by the Lyapunov exponents in global theory, and the consistency of the two indexes is confirmed. We further study the dynamic characteristics of the quantum walk and show that the probabilities are localized to some specific lattice sites with time evolution. This phenomenon is explained by the effective potential of the Hamiltonian which corresponds to the phase in the coin operator of the quantum walk.

Effectiveness of the A3 robot on lower extremity motor function in stroke patients:A prospective,randomized controlled trial

BACKGROUND The results of existing lower extremity robotics studies are conflicting,and few relevant clinical trials have examined short-term efficacy.In addition,most of the outcome indicators in existing studies are scales,which are not objective enough.We used the combination of objective instrument measurement and scale to explore the short-term efficacy of the lower limb A3 robot,to provide a clinical reference.AIM To investigate the improvement of lower limb walking ability and balance in stroke treated by A3 lower limb robot.METHODS Sixty stroke patients were recruited prospectively in a hospital and randomized into the A3 group and the control group.They received 30 min of A3 robotics training and 30 min of floor walking training in addition to 30 min of regular rehabilitation training.The training was performed five times a week,once a day,for 2 wk.The t-test or non-parametric test was used to compare the threedimensional gait parameters and balance between the two groups before and after treatment.RESULTS The scores of basic activities of daily living,Stroke-Specific Quality of Life Scale,FM balance meter,Fugl-Meyer Assessment scores,Rivermead Mobility Index,Stride speed,Stride length,and Time Up and Go test in the two groups were significantly better than before treatment(19.29±12.15 vs 3.52±4.34;22.57±17.99 vs 4.07±2.51;1.21±0.83 vs 0.18±0.40;3.50±3.80 vs 0.96±2.08;2.07±1.21 vs 0.41±0.57;0.89±0.63 vs 0.11±0.32;12.38±9.00 vs 2.80±3.43;18.84±11.24 vs 3.80±10.83;45.12±69.41 vs 8.41±10.20;29.45±16.62 vs 8.68±10.74;P<0.05).All outcome indicators were significantly better in the A3 group than in the control group,except the area of the balance parameter.CONCLUSION For the short-term treatment of patients with subacute stroke,the addition of A3 robotic walking training to conventional physiotherapy appears to be more effective than the addition of ground-based walking training.

Strong invariance principle for a counterbalanced random walk

We study a counterbalanced random walkS_(n)=X_(1)+…+X_(n),which is a discrete time non-Markovian process andX_(n) are given recursively as follows.For n≥2,X_(n) is a new independent sample from some fixed law̸=0 with a fixed probability p,andX_(n)=−X_(v(n))with probability 1−p,where v(n)is a uniform random variable on{1;…;n−1}.We apply martingale method to obtain a strong invariance principle forS_(n).

Enhancing personalized exercise recommendation with student and exercise portraits

The exercise recommendation system is emerging as a promising application in online learning scenarios,providing personalized recommendations to assist students with explicit learning directions.Existing solutions generally follow a collaborative filtering paradigm,while the implicit connections between students(exercises)have been largely ignored.In this study,we aim to propose an exercise recommendation paradigm that can reveal the latent connections between student-student(exercise-exercise).Specifically,a new framework was proposed,namely personalized exercise recommendation with student and exercise portraits(PERP).It consists of three sequential and interdependent modules:Collaborative student exercise graph(CSEG)construction,joint random walk,and recommendation list optimization.Technically,CSEG is created as a unified heterogeneous graph with students’response behaviors and student(exercise)relationships.Then,a joint random walk to take full advantage of the spectral properties of nearly uncoupled Markov chains is performed on CSEG,which allows for full exploration of both similar exercises that students have finished and connections between students(exercises)with similar portraits.Finally,we propose to optimize the recommendation list to obtain different exercise suggestions.After analyses of two public datasets,the results demonstrated that PERP can satisfy novelty,accuracy,and diversity.

Functional Capacity of Patients with Venous Thromboembolic Disease Six to Twelve Months after Treatment

Background: Venous thromboembolism (VTE) is among the leading causes of hospital-related disability-adjusted life years lost. We aimed to determine the prevalence and determinants of functional capacity impairment six to twelve months after an acute VTE event. Methods: This was a cross-sectional study conducted between January and April 2021 in two referral hospitals of Yaoundé, including consenting adult patients admitted to these hospitals six to twelve months ago for VTE. We excluded dead patients and those with any comorbidity or symptoms limiting physical activity. The functional outcome was assessed with the six-minute walk test. Functional capacity impairment was defined as walking distance lower than the expected value. Results: We included 27 cases in this study with a mean age of 53.2 ± 14.4 years. The prevalence of functional capacity impairment was 29.6% (95% CI: 14.8 - 48.1). Factors associated with poor functional outcome were obesity (OR: 59.5;95% CI: 4.6 - 767.2;p - 207.4;p = 0.017), massive PE (OR: 30;95% CI: 2.5 - 354;p = 0.004), and poor adherence to treatment (OR: 30.3;95% CI: 2.5 - 333.3;p = 0.004). Conclusion: Functional capacity impairment is common in the medium-term after VTE and factors associated with this poor outcome are obesity, the severity of the VTE, and poor adherence to treatment.

“具身化”理论下青年城市漫游现象兴起的社会学透视

城市漫游(City Walk)是当下流行的一种青年文化,其本质是在行走中同自我、他者与城市进行互动,积极地连接微观的身体与宏观的城市。以“具身化”为理论视角,运用参与式观察与深入访谈的方法进行研究。分别从具身节奏、具身情感与具身体验三个维度进行分析,发现青年在City Walk的实践中具有松弛感、放空感与真实感。对于现代社会中的青年来说,City Walk有三个很重要的价值:逃离技术规训、寻求自我认同和追寻生活意义。总之,City Walk是当下青年在城市诗意栖居的一场具身实践,其背后有着丰富的社会性隐喻,可以促使我们思考城市、身体与现代性的关系。

Supervised vs home-based exercise program in kidney transplant recipients: A pilot pragmatic non-randomized study

BACKGROUND Although the benefits of exercise for kidney transplant recipients(KTRs)have been widely demonstrated,these patients experience several barriers in undertaking a structured exercise program in hospital and non-hospital facilities.AIM To compare the effects of a supervised moderate-intensity gym-based intervention with a home-based low-intensity walking program on exercise capacity in KTRs.METHODS KTRs were asked to choose between two six-month programs.The first group performed a low-intensity interval walking intervention at home-based exercise intervention (HBex). The second group performed a supervised training program at an adapted physical activitygym (Sgym), including aerobic and resistance training. The outcomes, collected at baseline and at the end of theprograms, included the 6-minute walking test, the peak oxygen consumption (VO_(2)peak) during a treadmill test,the 5-time sit-to-stand test, and blood pressure.RESULTSSeventeen patients agreed to participate and self-selected into the HBex (n = 9) and Sgym (n = 8) groups. Twopatients in the Sgym group dropped out because of familial problems. At baseline, patients in the HBex group weresignificantly older and had lower walking distance, VO_(2)peak, and lower limb strength. Primary outcome changeswere significantly greater in the HBex group than in the Sgym group (52 ± 23 m vs 8 ± 34;P = 0.005). No othersignificant differences between groups were observed. Both groups improved most of the outcomes in the withingroupcomparisons, with significant variations in VO_(2) peak.CONCLUSIONSix-month moderate-intensity supervised or low-intensity home-based training programs effectively improvedexercise capacity in KTRs. Gym-based programs combine aerobic and resistance training;however, in-homewalking may be proposed for frail KTRs.

从“走向自然”到“走向城市”:休闲美学视域下的City Walk

“如何休闲”之问具有“顶天立地”的双重品格,既关乎具体可感的现实生活样态,又牵涉本己本真的存在与生命之思。以往,人们通过践履山水自然而追寻人性自然。而今,“走向自然”的休闲难以与日常生活相协调,亟待思考的是如何另辟蹊径。City Walk是一种时兴的、以徒步为主要方式来探索城市空间、感受别样趣味的休闲活动,其低成本、慢节奏、益身心等特点极大地推动了休闲的开展,其“反叛技术”“背离秩序”的超越性品格规避了休闲异化的风险,其维持身心健康、促进友好交往、建构和谐关系及回归诗意栖居的美学价值助力人们属人地生存与属人地休闲。研究其活动特质与美学价值,既可为休闲美学添砖加瓦,又可为城市生活建言献策。

A Bayesian Mixture Model Approach to Disparity Testing

The topic of this article is one-sided hypothesis testing for disparity, i.e., the mean of one group is larger than that of another when there is uncertainty as to which group a datum is drawn. For each datum, the uncertainty is captured with a given discrete probability distribution over the groups. Such situations arise, for example, in the use of Bayesian imputation methods to assess race and ethnicity disparities with certain insurance, health, and financial data. A widely used method to implement this assessment is the Bayesian Improved Surname Geocoding (BISG) method which assigns a discrete probability over six race/ethnicity groups to an individual given the individual’s surname and address location. Using a Bayesian framework and Markov Chain Monte Carlo sampling from the joint posterior distribution of the group means, the probability of a disparity hypothesis is estimated. Four methods are developed and compared with an illustrative data set. Three of these methods are implemented in an R-code and one method in WinBUGS. These methods are programed for any number of groups between two and six inclusive. All the codes are provided in the appendices.

The Master of Tea

His second method is more direct:“Come to my house,let’s have tea.”With this method,you are destined to follow him.Needless to say,Cha Ye’s great prestige and seniority on Old Street makes you feel it is a great privilege if he asks you to tea.It was a sultry day in July.As Cha Ye strolled down the street,he noticed a noise.It was Mr.Hu,boss of the Heshengzhai Antique Shop.Cha Ye walked into the antique shop,where he saw Hu holding onto a strong man’s arm,not letting him go.