Single-subject analysis reveals varied knee mechanics during step landing in response to isokinetic fatigue of the quadriceps

Introduction: The ability to regulate joint stiffness and coordinate movement during landing when impaired by muscle fatigue has important implications for knee function. Unfortunately, the literature examining fatigue effects on landing mechanics suffers from a lack of consensus. Inconsistent results can be attributed to variable fatigue models, as well as grouping variable responses between individuals when statistically detecting differences between conditions. There remains a need to examine fatigue effects on knee function during landing with attention to these methodological limitations. Aim: The purpose of this study therefore, was to examine the effects of isokinetic fatigue on pre-impact muscle activity and post-impact knee mechanics during landing using singlesubject analysis. Methodology: Sixteen male university students (22.6+3.2 yrs; 1.78+0.07 m; 75.7+6.3 kg) performed maximal concentric and eccentric knee extensions in a reciprocal manner on an isokinetic dynamometer and step-landing trials on 2 occasions. On the first occasion each participant performed 20 step-landing trials from a knee-high platform followed by 75 maximal contractions on the isokinetic dynamometer. The isokinetic data was used to calculate the operational definition of fatigue. On the second occasion, with a minimum rest of 14 days, participants performed 2 sets of 20 step landing trials, followed by isokinetic exercise until the operational definition of fatigue was met and a final post-fatigue set of 20 step-landing trials. Results: Single-subject analyses revealed that isokinetic fatigue of the quadriceps induced variable responses in pre impact activation of knee extensors and flexors (frequency, onset timing and amplitude) and post-impact knee mechanics(stiffness and coordination). In general however, isokinetic fatigue induced sig nificant (p<0.05) reductions in quadriceps activation frequency, delayed onset and increased amplitude. In addition, knee stiffness was significantly (p<0.05) increased in some individuals, as well as impaired sagittal coordination. Conclusions: Pre impact activation and post-impact mechanics were adjusted in patterns that were unique to the individual, which could not be identified using traditional group-based statistical analysis. The results suggested that individuals optimised knee function differently to satisfy competing demands, such as minimising energy expenditure, as well as maximising joint stability and sensory information.

Assessing the representativeness of a groundwater quality monitoring network

The monitoring sites comprising a state of the environment (SOE) network must be carefully selected to ensure that they will be representative of the broader resource. Hierarchical cluster analysis (HCA) is a data-driven technique that can potentially be employed to assess the representativeness of a SOE monitoring network. The objective of this paper is to explore the use of HCA as an approach for assessing the representativeness of the New Zealand National Groundwater Monitoring Programme (NGMP), which is comprised of 110 monitoring sites across the country.

Neural network-based detection of virtual environment anomalies

The increasingly widespread use of large-scale 3D virtual environments has translated into an increasing effort required from designers, developers and testers. While considerable research has been conducted into assisting the design of virtual world content and mechanics, to date, only limited contributions have been made regarding the automatic testing of the underpinning graphics software and hardware. In the work presented in this paper, two novel neural network-based approaches are presented to predict the correct visualization of 3D content. Multilayer perceptrons and self-organizing maps are trained to learn the normal geometric and color appearance of objects from validated frames and then used to detect novel or anomalous renderings in new images. Our approach is general, for the appearance of the object is learned rather than explicitly represented. Experiments were conducted on a game engine to determine the applicability and effectiveness of our algorithms. The results show that the neural network technology can be effectively used to address the problem of automatic and reliable visual testing of 3D virtual environments.

Smart grid-demand side response model for optimization air conditioning

The growing demand of air-conditioning is one of the largest contributors to Australia’s overall electricity consumption. This has started to create peak load supply problems for some electricity utilities particularly in Queensland. This research aimed to develop consumer demand side response model to assist electricity consumers to mitigate peak demand on the electrical network. The model developed demand side response model to allow consumers to manage and control air conditioning for every period, it is called intelligent control. This research investigates optimal response of end-user toward electricity price for several cases in the near future, such as: no spike, spike and probability spike price cases. The results indicate the potential of the scheme to achieve energy savings, reducing electricity bills (costs) to the consumer and targeting best economic performance for electrical generation distribution and transmission.

Development of network-level project screening methods supporting the 4-Year pavement management plan in Texas

The Texas Department of Transportation (TxDOT) is concerned about the widening gap between pavement preservation needs and available funding. Thus, the TxDOT Austin District Pavement Engineer (DPE) has investigated methods to strategically allocate available pavement funding to potential projects that improve the overall performance of the District and Texas highway systems. The primary objective of the study presented in this paper is to develop a network-level project screening and ranking method that supports the Austin District 4-year pavement management plan development. The study developed candidate project selection and ranking algorithms that evaluated pavement conditions of each project candidate using data contained in the Pavement Management Information system (PMIS) database and incorporated insights from Austin District pavement experts; and implemented the developed method and supporting algorithm. This process previously required weeks to complete, but now requires about 10 minutes including data preparation and running the analysis algorithm, which enables the Austin DPE to devote more time and resources to conducting field visits, performing project-level evaluation and testing candidate projects. The case study results showed that the proposed method assisted the DPE in evaluating and prioritizing projects and allocating funds to the right projects at the right time.

Probability analysis of machine angle stability with non-gaussian wind power input

The security of power transfer across a given transmission link is typically a steady state assessment. This paper develops tools to assess machine angle stability as affected by a combination of faults and uncertainty of wind power using probability analysis. The paper elaborates on the development of the theoretical assessment tool and demonstrates its efficacy using single machine infinite bus system.

National Institute for Clinical Studies Report for Phase 1, Evidence Uptake Network : Best Practice Community Care for Clients with Chronic Venous Leg Ulcers

Chronic leg ulcers cause significant pain, cost, decreased quality of life and morbidity for a considerable segment of the older population (Graham et al., 2003a). At any given time the prevalence of patients with open leg ulcers receiving treatment is between 0.11% - 0.18% (Briggs & Closs 2003). Chronic leg ulcers occur in approximately 1 - 2% of the over 60 population in the US, UK, Europe and Australia (Baker & Stacey 1994; Johnson 1995; Lees & Lambert 1992; Margolis et al. 2002). Considerable research has been undertaken to determine the best treatment practices that will aid in the management and the healing of these ulcers, and practical and effective strategies and techniques for healing venous leg ulcers have been trialled to demonstrate their beneficial effects (Nelson et al. 2004; Cullum et al. 2001)...

Larger or broader : performance implications of size and diversity of the knowledge worker's egocentric network. [更多或更广：知识员工个人中心网络大小和 多样性对绩效的影响]

Management scholars and practitioners emphasize the importance of the size and diversity of a knowledge worker's social network. Constraints on knowledge workers’ time and energy suggest that more is not always better. Further, why and how larger networks contribute to valuable outcomes deserves further understanding. In this study, we offer hypotheses to shed insight on the question of the diminishing returns of large networks and the specific form of network diversity that may contribute to innovative performance among knowledge workers. We tested our hypotheses using data collected from 93 R&D engineers in a Sino-German automobile electronics company located in China. Study findings identified an inflection point, confirming our hypothesis that the size of the knowledge worker's egocentric network has an inverted U-shaped effect on job performance. We further demonstrate that network dispersion richness (the number of cohorts that the focal employee has connections to) rather than network dispersion evenness (equal distribution of ties across the cohorts) has more influence on the knowledge worker's job performance. Additionally, we found that the curvilinear effect of network size is fully mediated by network dispersion richness. Implications for future research on social networks in China and Western contexts are discussed.

Australian Diabetes Foot Network : management of diabetes-related foot ulceration — a clinical update

Summary Appropriate assessment and management of diabetes-related foot ulcers (DRFUs) is essential to reduce amputation risk. Management requires debridement, wound dressing, pressure off-loading, good glycaemic control and potentially antibiotic therapy and vascular intervention. As a minimum, all DRFUs should be managed by a doctor and a podiatrist and/or wound care nurse. Health professionals unable to provide appropriate care for people with DRFUs should promptly refer individuals to professionals with the requisite knowledge and skills. Indicators for immediate referral to an emergency department or multidisciplinary foot care team (MFCT) include gangrene, limb-threatening ischaemia, deep ulcers (bone, joint or tendon in the wound base), ascending cellulitis, systemic symptoms of infection and abscesses. Referral to an MFCT should occur if there is lack of wound progress after 4 weeks of appropriate treatment.

The impact of fatigue caused by sprint running on the median power frequency of the hamstring muscle group

Hamstring strain injuries (HSI) are the predominant non-contact injury in many sports. Intermittent running has been shown to result in preferential reductions in eccentric hamstring strength, which increase the risk of sustaining a HSI. The eccentric specific nature of this decline in hamstring function implicates central mechanisms, as peripheral fatigue mechanisms tend to impact upon both concentric and eccentric contractions modes. However, neural function of the hamstrings, such as the median power frequency (MPF) of the surface electromyography signal has yet to be examined in the fatigued hamstring following intermittent sprint running. AIM: To determine the impact of fatigue induced by intermittent sprinting on the MPF of the medial and lateral hamstring muscles. METHODS: Fifteen recreationally active males completed 18 × 20m overground sprints. Maximal strength (concentric and eccentric knee flexor and concentric knee extensor) was determined isokinetically at the velocities of ±180.s-1 and ±60.s- while hamstring muscle activation was assessed using surface electromyography, before and 15 minutes after the running protocol. RESULTS: Overground intermittent running caused a significant reduction in eccentric knee flexor strength (27.2 Nm; 95% CI = 11.2 to 43.3; p=0.0001) but not concentric strength (9.3 Nm; 95% CI = -6.7 to 25.3; P=0.6361). Following the overground running, MPF of the lateral hamstrings showed a significant decline eccentrically (0.86; 95% CI = 0.59 to 1.54; P=0.038) and concentrically (0.76; 95%CI = 0.66 to 0.83; P=0.039). Similar declines in MPF were also noted in the medial hamstrings eccentrically (1.54; 95% CI = 0.59 to 7.9; P=0.005) and concentrically (1.18; 95% CI = 0.44 to 6.8; P=0.040). CONCLUSION: Whilst sprint running induced fatigue led to a eccentric specific reduction in knee flexor torque, MPF was suppressed across both contraction modes. This would indicate that factors associated with the decline in MPF do not appear to explain the contraction mode-specific loss of strength after intermittent sprints. This would implicate other central mechanisms, such as declines in voluntary activation, in explaining the eccentric specific decline in strength seen following sprint running.

How do perceptions of risk associated with driving while fatigued and perceptions of effectiveness of countermeasures effect willingness to engage in fatigue reducing countermeasures?

Sleep-related and fatigue-related driving is an important contributory factor in fatal and serious injury crashes - Accounts for approx 19% - Similar in magnitude to drink driving

A longitudinal study of health-related quality of life, fatigue and physical activity in chronic kidney disease patients

This study assessed the health-related quality of life (HRQoL), fatigue and physical activity levels of 28 persons with chronic kidney disease (CKD) on initial administration of an erythropoietin stimulating agent, and at 3 months, 6 months and 12 months. The sample comprised of 15 females and 13 males whose ages ranged from 31 to 84 years. Physical activity was measured using the Human Activity Profile (HAP): Self-care, Personal/Household work, Entertainment/Social, Independent exercise. Quality of life was measured using the SF-36 which gives scores on physical health (physical functioning, role-physical, bodily pain and general health) and mental health (vitality, social functioning, role-emotional and emotional well-being). Fatigue was measured by the Fatigue Severity Scale (FSS). Across all time points the renal sample engaged in considerably less HAP personal/household work activities and entertainment/social activities compared to healthy adults. The normative sample engaged in three times more independent/exercise activities compared to renal patients. One-way Repeated measures ANOVAs indicated a significant change over time for SF-36 scales of role physical, vitality, emotional well-being and overall mental health. There was a significant difference in fatigue levels over time [F(3,11) = 3.78, p<.05]. Fatigue was highest at baseline and lowest at 6 months. The more breathlessness the CKD patient reported, the fewer activities undertaken and the greater the reported level of fatigue. There were no significant age differences over time for fatigue or physical activity. Age differences were only found for SF-36 mental health at 3 months (t=-2.41, df=14, p<.05). Those younger than 65 years had lower emotional well-being compared to those aged over 65. Males had poorer physical health compared to females at 12 months. There were no significant gender differences on mental health at any time point. In the management of chronic kidney disease, early detection of a person’s inability to engage in routine activities due to fatigue is necessary. Early detection would enable timely interventions to optimise HRQoL and independent exercise.

Estimating the probability of an invalid match for matching using the rank transform

A fundamental problem faced by stereo matching algorithms is the matching or correspondence problem. A wide range of algorithms have been proposed for the correspondence problem. For all matching algorithms, it would be useful to be able to compute a measure of the probability of correctness, or reliability of a match. This paper focuses in particular on one class for matching algorithms, which are based on the rank transform. The interest in these algorithms for stereo matching stems from their invariance to radiometric distortion, and their amenability to fast hardware implementation. This work differs from previous work in that it derives, from first principles, an expression for the probability of a correct match. This method was based on an enumeration of all possible symbols for matching. The theoretical results for disparity error prediction, obtained using this method, were found to agree well with experimental results. However, disadvantages of the technique developed in this chapter are that it is not easily applicable to real images, and also that it is too computationally expensive for practical window sizes. Nevertheless, the exercise provides an interesting and novel analysis of match reliability.

Network interactions and performance of a multi-function IEC 61850 process bus

New substation technology, such as non-conventional instrument transformers,and a need to reduce design and construction costs, are driving the adoption of Ethernet based digital process bus networks for high voltage substations. Protection and control applications can share a process bus, making more efficient use of the network infrastructure. This paper classifies and defines performance requirements for the protocols used in a process bus on the basis of application. These include GOOSE, SNMP and IEC 61850-9-2 sampled values. A method, based on the Multiple Spanning Tree Protocol (MSTP) and virtual local area networks, is presented that separates management and monitoring traffic from the rest of the process bus. A quantitative investigation of the interaction between various protocols used in a process bus is described. These tests also validate the effectiveness of the MSTP based traffic segregation method. While this paper focusses on a substation automation network, the results are applicable to other real-time industrial networks that implement multiple protocols. High volume sampled value data and time-critical circuit breaker tripping commands do not interact on a full duplex switched Ethernet network, even under very high network load conditions. This enables an efficient digital network to replace a large number of conventional analog connections between control rooms and high voltage switchyards.