Algorithmically detectable directional changes in upper extremity motion indicate substantial myoelectric shoulder muscle fatigue during a repetitive manual task

Repetitive workplace tasks are associated with fatigue-induced changes to shoulder muscular strategies, potentially altering kinematics and elevating susceptibility to tissue overexposures. Accessible and reliable methods to detect shoulder muscle fatigue in the workplace are therefore valuable. Detectable changes in joint motion may provide a plausible fatigue identification method. In this investigation, the onset of the first kinematic changes, as identified by a symbolic motion representation (SMSR) algorithm, and the onset of substantial surface electromyography (sEMG) mean power frequency (MPF) fatigue were not significantly different, both occurring around 10% of task duration. This highlights the potential utility of SMSR identified directional changes in joint motion during repetitive tasks as a cue of substantial muscle fatigue, enabling ergonomics responses that can mitigate shoulder muscular fatigue accumulation and its associated deleterious physical effects.

Practitioner Summary: The onset of substantial muscle fatigue during a repetitive dynamic task was assessed using kinematics and myoelectric-based techniques. Algorithmically detectable directional changes in upper extremity joint motion occurred with the onset of substantial muscle fatigue, highlighting the potential of this as a useful approach for workplace fatigue identification.     

Result sequences

Expression evaluation in conventional programming languages may be viewed as a simplification of expression evaluation in the Icon programming language. The evaluation of an expression in Icon may yield a sequence of results. Goal-directed evaluation causes expressions to produce these results in an attempt to produce the successful evaluation of an enclosing expression. There are control operations that operate on result sequences. The study of expression evaluation in Icon therefore is more interesting than it is in most programming languages. This paper introduces a notation for result sequences and shows how it can be used to describe the static aspects of expression evaluation. Equivalences among control operations and expressions are demonstrated.     

Address sequences

A problem of generating modified address sequences is considered. The use of the Euclidean distance as a disparity measure for address sequences is substantiated. Numerical values of the Euclidean metric for modified address sequences are given. The efficiency of using the Euclidean metric to choose address sequences in case of the multiple run testing of modern memory devices is shown. Experimental results that support the utility of the Euclidean distance are provided.     

The relation between preset distinguishing sequences and synchronizing sequences

We study the relation between synchronizing sequences and preset distinguishing sequences which are some special sequences used in finite state machine based testing. We show that the problems related to preset distinguishing sequences can be converted into related problems of synchronizing sequences. Using the results existing in the literature for synchronizing sequences, we offer several reflections of these results for preset distinguishing sequences. Although computing a preset distinguishing sequence is PSPACE-hard , we do identify a class of machines for which computing a preset distinguishing sequence can be performed in polynomial time and argue that this class is practically relevant. We also present an experimental study to compare the performance of exponential brute-force and polynomial heuristic algorithms to compute a preset distinguishing sequence.     

Computing spectral sequences

John McCleary insisted in his interesting textbook entitled “User’s guide to spectral sequences” on the fact that the tool “spectral sequence” is not in the general situation an algorithm allowing its user to compute the looked-for homology groups. The present article explains how the notion of “Object with Effective Homology” on the contrary allows the user to recursively obtain all the components of the Serre and Eilenberg–Moore spectral sequences, when the data are objects with effective homology. In particular the computability problem of the higher differentials is solved, the extension problem at abutment is also recursively solved. Furthermore, these methods have been concretely implemented as an extension of the Kenzo computer program. Two typical examples of spectral sequence computations are reported.     

Weakly useful sequences

An infinite binary sequence x is defined to be

(i) strongly useful if there is a computable time bound within which every decidable sequence is Turing reducible to x; and

(ii) weakly useful if there is a computable time bound within which all the sequences in a non-measure 0 subset of the set of decidable sequences are Turing reducible to x.

Juedes, Lathrop, and Lutz [Theorectical Computer Science 132 (1994) 37] proved that every weakly useful sequence is strongly deep in the sense of Bennett [The Universal Turing Machine: A Half-Century Survey, 1988, 227] and asked whether there are sequences that are weakly useful but not strongly useful. The present paper answers this question affirmatively. The proof is a direct construction that combines the martingale diagonalization technique of Lutz [SIAM Journal on Computing 24 (1995) 1170] with a new technique, namely, the construction of a sequence that is “computably deep” with respect to an arbitrary, given uniform reducibility. The abundance of such computably deep sequences is also proven and used to show that every weakly useful sequence is computably deep with respect to every uniform reducibility.

Uniform tag sequences

Structural properties, local and asymptotic, of members of a class of simple, realtime generable sequences are analyzed.     

Decoding asynchronous sequences

The problem of decoding the input actions of a logical circuit with elements of vennjunction is solved. As the input action we will consider not individual suites of input signals, but instead sequences of such signals. These sequences are asynchronous in nature. A method of constructing a decoder based on a cascade connection of conjunctors is presented.     

一个新的极大独立集算法及独立数的界

最大独立集问题是图论中典型的组合优化问题,有着广泛的实际应用价值。分析了现有独立数的界公式后给出了新的上界公式,并通过分析贪婪算法和独立集自身的特征,给出了新的求解极大独立集的算法,并证明了其确定性。然后用实例验证了该算法的有效性。     

The independent policy evaluation

Abstract This article is based on the proposal for evaluation submitted to the ESRC by the authors. The proposal offered an independent policy evaluation which would help people outside the Programme to know and judge what is going on, and those taking part in the programme to take into better account the impact on others of their activities and findings. The thrust of the proposal is formative, and focuses on the communication of research knowledge both within the programme, and between the programme and various interest groups and policy-making bodies. The major concern of the evaluation is to understand and represent — through formative evaluation — the potential impact of the Programme on its intended audiences and users. This implies a focus on the research activities themselves (in so far as these emphases are separable). The relationship between the ESRC InTER Programme and the policy evaluation is an independent one. That is to say, the evaluation is sponsored by the ESRC, but is committed to independent internal and public reporting.
The methods favoured by this evaluation are known by the term 'naturalistic', so-called because they are like the ways in which people generally come to understand social life — looking, listening, and talking to people whose actions, experience and reasoning we have to represent and report in a useful form, and the article ends with a brief methodological justification for such an approach to policy evaluation.     

Interference between independent processes

The first time independent, parallel processes consisting of two alternating renewal functions, say function zero and one, will be in phase zero together under equilibrium and non-equilibrium starting conditions is found. With function one an exponential distribution and function zero a non-lattice type, the distribution of the aforementioned time is found by taking advantage of a point of renewal. Further results are derived when both functions are exponential with the same parameter value by likening the situation to an Ehrenfest model

The results are applicable to many situations. Examples taken from machine interference, reliability with redundancy, queueing at parallel stations, ‘ channel ’ interference in computer systems and communications nets are included.     

Principal independent component analysis

Conventional blind signal separation algorithms do not adopt any asymmetric information of the input sources, thus the convergence point of a single output is always unpredictable. However, in most of the applications, we are usually interested in only one or two of the source signals and prior information is almost always available. In this paper, a principal independent component analysis (PICA) concept is proposed. We try to extract the objective independent component directly without separating all the signals. A cumulant-based globally convergent algorithm is presented and simulation results are given to show the hopeful applicability of the PICA ideas.     

Least-squares independent component analysis

Accurately evaluating statistical independence among random variables is a key element of independent component analysis (ICA). In this letter, we employ a squared-loss variant of mutual information as an independence measure and give its estimation method. Our basic idea is to estimate the ratio of probability densities directly without going through density estimation, thereby avoiding the difficult task of density estimation. In this density ratio approach, a natural cross-validation procedure is available for hyperparameter selection. Thus, all tuning parameters such as the kernel width or the regularization parameter can be objectively optimized. This is an advantage over recently developed kernel-based independence measures and is a highly useful property in unsupervised learning problems such as ICA. Based on this novel independence measure, we develop an ICA algorithm, named least-squares independent component analysis.     

Implementing location independent invocation

The problems of finding objects in large and wide-area networks where objects may change their location in volatile memory as well as on stable storage are presented. The authors discuss possible solutions and describe those adopted in the Hermes system (a corporate wide, real life office application). They have designed and developed a location-independent-invocation (LII) mechanism that combines finding with invocation, using temporal location information. The mechanism also updates the system's knowledge of an object's location as a side-effect of invocation and object migration. Assumptions about object mobility indicate that objects are likely to be found within a few propagations of an invocation. If they cannot be found in this way, stable-storage and name services are used to locate the object. The major contribution of this work is to show how LII can be achieved in a large and dynamic environment in which objects are supported by neither are operating system nor the programming language     

Weakly independent database schemes

Independent database schemes are best known to have constraints enforced globally by enforcing them locally in individual relations, and therefore are highly desirable in an updates-busy and distributed environment. However, independence excludes all database schemes with interrelational functional dependencies and therefore is too strong a condition. In this paper, a natural generalization of independent schemes along this line, called weakly independent schemes, is defined. A database scheme is weakly independent with respect to a set of embedded functional dependencies if the constraints can be enforced globally by enforcing local as well as interrelational functional dependencies. (a) A characterization of the weak independence and an exponential time test (in the number of functional dependencies) are presented. (b) Two polynomial time conditions are also presented, one is necessary and the other is sufficient for a database scheme to be weakly independent. (c) It is shown that a certain acyclicity of the database scheme implies weak independence. Extension to the case of embedded functional dependencies plus the join dependency is also considered. Received: 18 July 1991 / 28 September 1995