H2 filter design for discrete‐time Markov jump linear systems with partly unknown transition probabilities

The H₂ filter design problem for discrete‐time Markov jump linear systems with partly unknown transition probabilities is addressed in this paper. The so‐called partly unknown transition probabilities cover two cases: one is that some unknown elements have known lower and upper bounds, the other is that some unknown elements have no information available. By employing Finsler's lemma and linear matrix inequality (LMI) technique, sufficient conditions are developed in the LMI setting to design an H₂ filter such that the filtering error system is mean‐square stable and at the same time satisfies a prescribed H₂ performance index. Numerical examples are presented to illustrate the effectiveness of the developed theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.     

Delay‐dependent robust H ∞ control for uncertain singular time‐delay system with Markovian jumping parameters

The problem of robust H _∞ control for a class of uncertain singular time‐delay systems with Markovian jumping parameters is addressed in this paper. The considered Markovian jump singular systems involve constant time delay and norm‐bounded uncertainties. On the basis of LMI approach, a delay‐dependent condition is proposed, which ensures the nominal Markovian jump singular system to be regular, impulse‐free and stochastically stable. From the delay‐dependent condition, a sufficient condition leading to the existence of a state feedback controller that guarantees the robust admissibility and the H _∞ performance is also given. A numerical example is given to demonstrate the applicability of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.     

Improved approach for passive stability of discrete‐time Markovian jump linear systems via mode‐dependent time‐delayed controllers

In this paper, we investigate the problem of passive stability for discrete‐time Markovian jump linear systems via mode‐dependent time‐delayed controllers by employing an improved free‐weighting matrix approach. A Markov process as discrete‐time, discrete‐state Markov process is considered. First, a new result of mode‐dependent stability analysis is first established for error systems without ignoring any terms in the derivative of Lyapunov–Krasovskii function by considering the relationship between the time‐varying delay and its upper bound. Then, the delay‐dependent passivity criterion is provided and a mode‐dependent time‐delayed controller is designed in terms of linear matrix inequalities. Finally, two numerical examples are given to illustrate the effectiveness and less conservativeness of our proposed method. Copyright © 2011 John Wiley & Sons, Ltd.     

Motor learning of a dynamic balance task: Influence of lower limb power and prior balance practice

Objectives

We wanted to verify if the “learning to learn” effect observed in the learning of visuomotor tasks is also present when learning a balance task, i.e., whether the learning rate of a balance task is improved by prior practice of similar balance tasks.

Robust delay‐range‐dependent stabilization for Markovian jump systems with mode‐dependent time delays and nonlinearities

This paper discusses the robust stabilization problem for a class of Markovian jump systems with nonlinear disturbances and time delays, which are time‐varying in intervals and depend on system mode. By exploiting a new Lyapunov–Krasovskii functional, which takes into account the range of delay and by making use of novel techniques, mean‐square exponential stability result is proposed. Based on the obtained stability condition, a sufficient condition for state feedback controller, which stabilizes system and maximizes the bound on nonlinear perturbations is derived in terms of linear matrix inequalities involving a convex optimization. Finally, illustrative examples are presented to show the benefits and effectiveness of the proposed approaches. Copyright © 2009 John Wiley & Sons, Ltd.     

Reliability of fitness tests using methods and time periods common in sport and occupational management

Context:

Fitness testing is used frequently in many areas of physical activity, but the reliability of these measurements under real-world, practical conditions is unknown.

Objective:

To evaluate the reliability of specific fitness tests using the methods and time periods used in the context of real-world sport and occupational management.

Design:

Cohort study.

Setting:

Eighteen different Cirque du Soleil shows.

Patients or Other Participants:

Cirque du Soleil physical performers who completed 4 consecutive tests (6-month intervals) and were free of injury or illness at each session (n = 238 of 701 physical performers).

Intervention(s):

Performers completed 6 fitness tests on each assessment date: dynamic balance, Harvard step test, handgrip, vertical jump, pull-ups, and 60-second jump test.

Main Outcome Measure(s):

We calculated the intraclass coefficient (ICC) and limits of agreement between baseline and each time point and the ICC over all 4 time points combined.

Results:

Reliability was acceptable (ICC > 0.6) over an 18-month time period for all pairwise comparisons and all time points together for the handgrip, vertical jump, and pull-up assessments. The Harvard step test and 60-second jump test had poor reliability (ICC < 0.6) between baseline and other time points. When we excluded the baseline data and calculated the ICC for 6-month, 12-month, and 18-month time points, both the Harvard step test and 60-second jump test demonstrated acceptable reliability. Dynamic balance was unreliable in all contexts. Limit-of-agreement analysis demonstrated considerable intraindividual variability for some tests and a learning effect by administrators on others.

Conclusions:

Five of the 6 tests in this battery had acceptable reliability over an 18-month time frame, but the values for certain individuals may vary considerably from time to time for some tests. Specific tests may require a learning period for administrators.     

火针治疗对跟腱末端病大鼠跟腱区组织病理变化影响的研究

目的:通过观察跟腱末端病大鼠在1次与4次火针治疗后末端止点部位病变状况,分析探讨火针治疗末端病的机制.方法:采用88只雄性SD大鼠.以"电击跳跃法"训练8周建立大鼠跟腱末端病模型,对治疗组80只鼠施以火针治疗1-4,火针治疗后处死大鼠,取大鼠跟腱末端进行HE染色,在显微镜下观察每个样本跟腱末端、纤维软骨区、跟骨区、腱骨...     

Spatial moving average risk smoothing

This paper introduces spatial moving average risk smoothing (SMARS) as a new way of carrying out disease mapping. This proposal applies the moving average ideas of time series theory to the spatial domain, making use of a spatial moving average process of unknown order to define dependence on the risk of a disease occurring. Correlation of the risks for different locations will be a function of m values (m being unknown), providing a rich class of correlation functions that may be reproduced by SMARS. Moreover, the distance (in terms of neighborhoods) that should be covered for two units to be found to make the correlation of their risks 0 is a quantity to be fitted by the model. This way, we reproduce patterns that range from spatially independent to long‐range spatially dependent. We will also show a theoretical study of the correlation structure induced by SMARS, illustrating the wide variety of correlation functions that this proposal is able to reproduce. We will also present three applications of SMARS to both simulated and real datasets. These applications will show SMARS to be a competitive disease mapping model when compared with alternative proposals that have already appeared in the literature. Finally, the application of SMARS to the study of mortality for 21 causes of death in the Comunitat Valenciana will allow us to identify some qualitative differences in the patterns of those diseases. Copyright © 2012 John Wiley & Sons, Ltd.     

The Effects of Two Adhesive Ankle-Taping Methods on Strength,Power, and Range of Motion in Female Athletes

Background

Taping is a ubiquitous strategy to help prevent ankle sprains. The restrictive qualities of various taping methods may impair athletic performance.

Objective

The objective of the study was to compare the Gibney closed basket weave taping method with heel-locks to heel-locks and figure-eights in order to determine their effect on vertical jump performance and active range of motion (ROM) before and after exercise.

Methods

Eleven female varsity basketball athletes were subjected to three conditions of no ankle support (control), heel-locks, and figure-eights. The dependent variables of ankle active ROM, plantarflexor maximum voluntary contraction and jump height for the countermovement jump (CMJ), drop jump (DJ), and concentric only squat jump (COSJ) were randomly ordered. Following taping or control conditions, participants were pre-tested, completed a ten-minute treadmill run at 9.6 km/hr with a 3 minute cool down and then repeated the testing procedures.

Results

There were no significant differences in jump performance between taping methods or the effect of exercise. However significant differences for pre-/post-exercise for plantarflexor (p < 0.0001) and dorsiflexor (p = 0.007) active ROM and between no support and taping for plan-tarflexor ROM (p = 0.004) was found.

Conclusions

Despite plantarflexor active ROM being restricted by both taping procedures compared to the control, no effect on jump performance occurred.