Activation reduction following an eccentric contraction impairs torque steadiness in the isometric steady-state

Background:The isometric steady-state following active lengthening is associated with greater torque production and lower activation,as measured by electromyographic activity(EMG),in comparison with a purely isometric contraction(ISO)at the same joint angle.This phenomenon is termed residual force enhancement(RFE).While there has been a great deal of research investigating the basic mechanisms of RFE,little work has been performed to understand the everyday relevance of RFE.The purpose of this study was to investigate whether neuromuscular control strategies differ between ISO and RFE by measuring torque steadiness of the human ankle plantar flexors.Methods:Following ISO maximal voluntary contractions in 12 males(25±4 years),an active lengthening contraction was performed at 15°/s over a 30°ankle excursion,ending at the same joint angle as ISO(5°dorsiflexion;RFE).Surface EMG of the tibialis anterior and soleus muscles was recorded during all tasks.Torque steadiness was determined as the standard deviation(SD)and coefficient of variation(CV)of the torque trace in the ISO and RFE condition during activation-matching(20%and 60%integrated EMG)and torque-matching(20%and 60%maximal voluntary contraction)experiments.Two-tailed,paired t tests were used,within subjects,to determine the presence of RFE/activation reduction(AR)and whether there was a difference in torque steadiness between ISO and RFE conditions.Results:During the maximal and submaximal conditions,there was 5%-9%RFE with a 9%-11%AR(p<0.05),respectively,with no difference in antagonist coactivation between RFE and ISO(p>0.05).There were no differences in SD and CV of the torque trace for the 20%and60%activation-matching or the 60%and maximal torque-matching trials in either the RFE or ISO condition(p>0.05).During the 20%torquematching trial,there were～37%higher values for SD and CV in the RFE as compared with the ISO condition(p<0.05).A significant moderate-to-strong negative relationship was identified between the reduction in torque steadiness following active lengthening and the accompanying AR(p<0.05).Conclusion:It appears that while the RFE-associated AR provides some improved neuromuscular economy,this comes at the cost of increased torque fluctuations in the isometric steady-state following active lengthening during submaximal contractions.

A Study on the Transmission Dynamics of the Omicron Variant of COVID-19 Using Nonlinear Mathematical Models

This research examines the transmission dynamics of the Omicron variant of COVID-19 using SEIQIcRVW and SQIRV models,considering the delay in converting susceptible individuals into infected ones.The significant delays eventually resulted in the pandemic’s containment.To ensure the safety of the host population,this concept integrates quarantine and the COVID-19 vaccine.We investigate the stability of the proposed models.The fundamental reproduction number influences stability conditions.According to our findings,asymptomatic cases considerably impact the prevalence of Omicron infection in the community.The real data of the Omicron variant from Chennai,Tamil Nadu,India,is used to validate the outputs.

Averaged Dynamics of Fluids near the Oscillating Interface in a Hele-Shaw Cell

The steady flow in a Hele-Shaw cell filled with fluids with a high viscosity contrast in the presence of fluid oscillations is experimentally studied.The control of oscillatory dynamics of multiphase systems with interfaces is a challenging technological problem.We consider miscible(water and glycerol)and immiscible(water and high-viscosity silicone oil PMS-1000)fluids under subsonic oscillations perpendicular to the interface.Observations show that the interface shape depends on the amplitude and frequency of oscillations.The interface is undisturbed only in the absence of oscillations.Under small amplitudes,the interface between water and glycerol widens due to mixing.When the critical amplitude is reached,the interface becomes unstable to the fingering instability:Aqueous fingers penetrate the high-viscosity glycerol and induce intensive mixing of miscible fluids and associated decay of the instability.After the disappearance of the fingers,the interface takes a U-shape in the central part of the cell.A similar effect is observed for immiscible fluids:The oscillating interface tends to bend to the side of a high-viscosity fluid.Again,when the critical amplitude is reached,the fingering instability arises at the convex interface.This paper focuses on the causes of bending of the initially undisturbed interface between miscible or immiscible fluids.For this purpose,we measure the steady flow velocity near the interface and in the bulk of a high-viscosity fluid using Particle Image Velocimetry(PIV).

POSITIVE CLASSICAL SOLUTIONS OF DIRICHLET PROBLEM FOR THE STEADY RELATIVISTIC HEAT EQUATION

In this paper,for a bounded C2 domain,we prove the existence and uniqueness of positive classical solutions to the Dirichlet problem for the steady relativistic heat equation with a class of restricted positive C2 boundary data.We have a non-existence result,which is the justification for taking into account the restricted boundary data.There is a smooth positive boundary datum that precludes the existence of the positive classical solution.

Fourier neural operator with boundary conditions for efficient prediction of steady airfoil flows

An efficient data-driven approach for predicting steady airfoil flows is proposed based on the Fourier neural operator(FNO),which is a new framework of neural networks.Theoretical reasons and experimental results are provided to support the necessity and effectiveness of the improvements made to the FNO,which involve using an additional branch neural operator to approximate the contribution of boundary conditions to steady solutions.The proposed approach runs several orders of magnitude faster than the traditional numerical methods.The predictions for flows around airfoils and ellipses demonstrate the superior accuracy and impressive speed of this novel approach.Furthermore,the property of zero-shot super-resolution enables the proposed approach to overcome the limitations of predicting airfoil flows with Cartesian grids,thereby improving the accuracy in the near-wall region.There is no doubt that the unprecedented speed and accuracy in forecasting steady airfoil flows have massive benefits for airfoil design and optimization.

A Fixed-Point Fast Sweeping WENO Method with Inverse Lax-Wendroff Boundary Treatment for Steady State of Hyperbolic Conservation Laws

Fixed-point fast sweeping WENO methods are a class of efficient high-order numerical methods to solve steady-state solutions of hyperbolic partial differential equations(PDEs).The Gauss-Seidel iterations and alternating sweeping strategy are used to cover characteristics of hyperbolic PDEs in each sweeping order to achieve fast convergence rate to steady-state solutions.A nice property of fixed-point fast sweeping WENO methods which distinguishes them from other fast sweeping methods is that they are explicit and do not require inverse operation of nonlinear local systems.Hence,they are easy to be applied to a general hyperbolic system.To deal with the difficulties associated with numerical boundary treatment when high-order finite difference methods on a Cartesian mesh are used to solve hyperbolic PDEs on complex domains,inverse Lax-Wendroff(ILW)procedures were developed as a very effective approach in the literature.In this paper,we combine a fifthorder fixed-point fast sweeping WENO method with an ILW procedure to solve steadystate solution of hyperbolic conservation laws on complex computing regions.Numerical experiments are performed to test the method in solving various problems including the cases with the physical boundary not aligned with the grids.Numerical results show highorder accuracy and good performance of the method.Furthermore,the method is compared with the popular third-order total variation diminishing Runge-Kutta(TVD-RK3)time-marching method for steady-state computations.Numerical examples show that for most of examples,the fixed-point fast sweeping method saves more than half CPU time costs than TVD-RK3 to converge to steady-state solutions.

A Fourth-Order Unstructured NURBS-Enhanced Finite Volume WENO Scheme for Steady Euler Equations in Curved Geometries

In Li and Ren(Int.J.Numer.Methods Fluids 70:742–763,2012),a high-order k-exact WENO finite volume scheme based on secondary reconstructions was proposed to solve the two-dimensional time-dependent Euler equations in a polygonal domain,in which the high-order numerical accuracy and the oscillations-free property can be achieved.In this paper,the method is extended to solve steady state problems imposed in a curved physical domain.The numerical framework consists of a Newton type finite volume method to linearize the nonlinear governing equations,and a geometrical multigrid method to solve the derived linear system.To achieve high-order non-oscillatory numerical solutions,the classical k-exact reconstruction with k=3 and the efficient secondary reconstructions are used to perform the WENO reconstruction for the conservative variables.The non-uniform rational B-splines(NURBS)curve is used to provide an exact or a high-order representation of the curved wall boundary.Furthermore,an enlarged reconstruction patch is constructed for every element of mesh to significantly improve the convergence to steady state.A variety of numerical examples are presented to show the effectiveness and robustness of the proposed method.

Management Tools for Random Demand Inventory and Supply

A mathematical management model’s added value is obtained only after the design and implementation of a user-friendly operating and usage tool. Fol-lowing work on developing an automated inventory management system and/or supplies, a dynamic model for the rational management of product stocks was established. Its implementation aims to limit or eliminate over-stocking and/or stock depletion. The orderable quantity prediction tool based on a settable and preset time period demonstrates the added value of incorporating probabilistic mathematical principles into supply management processes. In this context, this article discusses aspects of the design and implementation of random demand management algorithms based on Mar-kov chains. The goal is to forecast the state or behavior of goods marketing company’s product stocks and to develop a user supply management inter-face. The latter’s functional application will ultimately demonstrate the ac-curacy of the model. This paper also looks at how to use Markov chains to predict the reliability of any technical device, as well as how to implement an automated system with the desired technical specifications.

The Black Hole Spray and the Cosmic Web

We propose that the trapped antimatter in super massive black hole ergoregions acts as detonators that triggers black hole to white hole transitions creating huge BHs explosions that generate BH spray that acts as seeds for new galaxies creation. We propose that by mapping and simulating the cosmic web structure, it may be possible to learn if the universe was created in a single big bang that started a single chain of BH explosions mini-creation event cycles, or alternatively, the BH explosions mini-creation event cycles are uncorrelated spacelike events, and the universe had no single primeval atom beginning. .

A Method of SSVEP Signal Identification Based on Improved eCAA

Brain-computer interfaces(BCI)based on steady-state visual evoked potentials(SSVEP)have attracted great interest because of their higher signal-to-noise ratio,less training,and faster information transfer.However,the existing signal recognition methods for SSVEP do not fully pay attention to the important role of signal phase characteristics in the recognition process.Therefore,an improved method based on extended Canonical Correlation Analysis(eCCA)is proposed.The phase parameters are added from the stimulus paradigm encoded by joint frequency phase modulation to the reference signal constructed from the training data of the subjects to achieve phase constraints on eCCA,thereby improving the recognition performance of the eCCA method for SSVEP signals,and transmit the collected signals to the robotic arm system to achieve control of the robotic arm.In order to verify the effectiveness and advantages of the proposed method,this paper evaluated the method using SSVEP signals from 35 subjects.The research shows that the proposed algorithm improves the average recognition rate of SSVEP signals to 82.76%,and the information transmission rate to 116.18 bits/min,which is superior to TRCA and traditional eCAA-based methods in terms of information transmission speed and accuracy,and has better stability.

STEADI跌倒风险自评量表在社区老年人中的应用研究

目的应用STEADI跌倒风险自评量表筛查社区老年人跌倒风险,并了解其对老年人远期跌倒的预测效能。方法采用多阶段整群随机抽样,选取重庆市社区老年人1 168人,运用汉化版STEADI跌倒风险自评量表筛查其跌倒风险。6个月后电话随访老年人跌倒发生情况。结果 321人(27.5%)自评有跌倒风险。6个月后有效电话随访825人,64人发生跌倒,跌倒发生率为7.8%(64/825),跌伤率为71.9%(46/64)。汉化版预测6个月后社区老年人发生跌倒的灵敏度为45.3%,特异性为75.4%,AUC为0.604,约登指数为0.208。71.6%的老年人认为跌倒风险自我评估对其有意义,69.9%的老年人评估后实施了预防跌倒的相关措施。结论大多数老年人认可跌倒风险自评的意义并采取相关措施预防跌倒,但汉化版预测社区老年人6个月后发生跌倒的效能欠佳,建议结合步态、力量和平衡的评估结果来预测老年人跌倒风险。

基于STEADI工具包筛查重庆市社区老人跌倒情况

目的:应用STEADI工具包筛查社区老人跌倒情况并分析影响因素。方法:2019年1月-4月采取多阶段整群抽样的方法,抽取重庆市某社区内符合纳入标准的老人为研究对象,运用汉化版STEADI工具包对其进行跌倒筛查。结果:共纳入1168名老人,其中跌倒低风险老人896人(76.71%),中风险老人251人(21.49%),高风险老人21人(1.80%);跌倒总发生率为14.98%,其中高风险、中风险、低风险组老人跌倒发生率分别为100.00%、18.33%、12.05%。3组老人在受教育程度、是否独居、生活照料情况、跌倒史、步态或平衡异常等项目得分差异有统计学意义(P<0.05)。结论:老人的跌倒受多种因素影响,应根据其跌倒风险等级制定分层干预策略。

STEADI工具包特点及其在预防老年人跌倒中的应用进展

本文综述了STEADI工具包的特点、应用现状及应用前景,为我国防范老年人跌倒提供新思路。

1980年代“文化热”的知识谱系与意识形态(下)

四、"文化"的位置认为这三个核心文本提供了三种叙事,并不是要强调彼此之间的差异有多大,相反,这些叙事之所以能够成立并以"文化热"的形式产生广泛的社会影响,正因为它们分享着统一的话语逻辑和历史想象,其核心在"文化"与"现代化"及其相互关系的理解。在很长的时间当中,人们对这两个80年代的关键词一直保持着与历史当事人同样的理解方式。

S_Schema及其关系映射方法

本文根据 W3C最新提出的 XML Schema规范,提出了一种等价于 XML Schema的数据模型S-Schema,并实现了S-Schema到关系模式的生成算法和XML文档到关系数据库的加载算法。实验证明,S-Schema方法在数据转储过程中的信息保持、映射后的查询更新操作等方面的综合性能要优于文本、Xparent方法。

STEADI工具包对我国住院患者跌倒预防的启示

该文综述了STEADI工具包的研发背景,工具包内容及目前在住院患者跌倒防范的应用研究,阐述了我国住院患者跌倒预防现状,包括国家对跌倒防范工作的重视程度,目前住院患者跌倒主要研究内容为我国跌倒防范预防主要工具及跌倒防范工作中存在的不足,同时提出了STEADI工具包对我国住院患者跌倒防范的启示,旨在为我国住院患者跌倒防范提供新工具,打开新思路。

List流上梯度Steady Solitons的位势函数

利用比较定理,研究了List流上梯度Steady Solitons的位势函数下确界的退化率,并得到了如下结论:如果位势函数是有界的,则梯度Steady Solitons一定是平凡的;梯度Steady Solitons的广义数量曲率不具有一致正下界.

社区老年人STEADI跌倒防范策略的实施

目的降低社区老年人跌倒发生率。方法采取多阶段整群抽样的方法,应用STEADI相关工具和自制的老年人足问题图册,筛查894名社区老年人跌倒风险和足问题,在此基础上根据STEADI跌倒风险分级干预策略,对社区老年人跌倒危险因素进行分层级、跨学科干预6个月。结果社区老年人跌倒低风险705人(78.9%),中风险175人(19.6%),高风险14人(1.6%)。老年人存在足部问题790人,其中存在与跌倒密切相关的足部疼痛和足部结构问题者333人(42.2%)。干预前发生跌倒135人(15.1%),干预后发生跌倒51人(6.2%,随访818人),跌倒发生率显著低于干预前(P<0.01)。结论STEADI跌倒防范策略有利于降低社区老年人跌倒发生率,可用于社区老年人跌倒的防范。

美国STEADI工具介绍及其对我国跌倒防范的启示

介绍美国疾病预防控制中心(CDC)2015年9月发布的预防老年人意外、死亡、伤害工具(Stopping Elderly Accidents,Deaths&Injuries Tool Kit,STEADI),旨在为我国老年人的跌倒防范提供参考和借鉴。

Effect of cooling rate during quenching on the microstructure and creep property of nickel-based superalloy FGH96

The effect of cooling rate during quenching on the microstructure and creep property of nickel-based superalloy FGH96 was investigated. Three groups of samples were quenched continuously with three fixed cooling rates, respectively, then subjected to a creep test under a constant load of 690 MPa at 700℃. Clear differences in size of secondary γ′ precipitates, creep properties and substructure of creep-tested samples were observed. The quantitative relationship among cooling rate, the size of secondary γ′ precipitates, and steady creep rate was constructed. It was found that with increasing cooling rate, the size of secondary γ′ precipitates decreases gradually, showing that the relationship between the size of secondary γ′ precipitates and the cooling rate obeys a power law, with an exponent of about –0.6, and the creep rate of steady state follows a good parabola relationship with cooling γ′ precipitate size. For 235℃/min, FGH96 alloy exhibited very small steady creep rate. The density of dislocation was low, and the isolated stacking fault was the dominant deformation mechanism. With decreasing cooling rates, the density of dislocation increased remarkably, and deformation microtwinning was the dominant deformation process. Detailed mechanisms for different cooling rate were discussed.