THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Muscle fatigue is an exercise-induced reduction in maximal voluntary muscle force. It may arise not only because of peripheral changes at the level of the muscle, but also because the central nervous system fails to drive the motoneurons adequately. Evidence for “central” fatigue and the neural mechanisms underlying it are reviewed, together with its terminology and the methods used to reveal it. Much data suggest that voluntary activation of human motoneurons and muscle fibers is suboptimal and thus maximal voluntary force is commonly less than true maximal force. Hence, maximal voluntary strength can often be below true maximal muscle force. The technique of twitch interpolation has helped to reveal the changes in drive to motoneurons during fatigue. Voluntary activation usually diminishes during maximal voluntary isometric tasks, that is central fatigue develops, and motor unit firing rates decline. Transcranial magnetic stimulation over the motor cortex during fatiguing exercise has revealed focal cha...

Spinal and Supraspinal Factors in Human Muscle Fatigue

/pdf/chapter-4-european-guidelines-for-the-management-of-chronic-4lrtve55lo.pdf

Chapter 4. European guidelines for the management of chronic nonspecific low back pain.

: This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series. Two approaches to feature selection are used. First, a subset enumeration method is used to determine which financial indicators are most useful for aiding in prediction of the S&P 500 futures daily price. The candidate indicators evaluated include RSI, Stochastics and several moving averages. Results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages. The second approach to feature selection is calculation of individual saliency metrics. A new decision boundary-based individual saliency metric, and a classifier independent saliency metric are developed and tested. Ruck's saliency metric, the decision boundary based saliency metric, and the classifier independent saliency metric are compared for a data set consisting of the RSI and Stochastics indicators as well as delayed closing price values. The decision based metric and the Ruck metric results are similar, but the classifier independent metric agrees with neither of the other metrics. The nine most salient features, determined by the decision boundary based metric, are used to train a neural network and the results are presented and compared to other published results. (AN)

/pdf/nonlinear-time-series-analysis-1j3a35n4y3.pdf

Nonlinear Time Series Analysis.

1. Introduction 2. Concepts, theories and models, and types of measurements 3. The development of a measurement instrument 4. Field testing - item reduction and data structure 5. Reliability 6. Validity 7. Responsiveness 8. Interpretation 9. Systematic reviews of measurement properties Index.

Measurement in Medicine: A Practical Guide

The articular surfaces of the tibiofemoral jointcommonly appear to have gaps in between during Arthroscopy operations. However, the same joint surfaces appear to be in contact inMR images. This discrepancy may be attributed to the pressure of the saline injected into the joint duringarthroscopy operations, insertion of cannulas, or anesthesia and the resulting absence of compressive force on the joint. This study examines the effect of these factors. Seven candidates of knee arthroscopysurgery participated in the study. The tibiofemoral joint space was observed with the arthroscope in different knee and hip flexion angles, with and without saline pressure, and with and without external compressive load. In the totally extended knee position, the joint was closed on both the lateral and medial sides. In the flexed knee positions, some of the joints showed a gap in either medial or lateral sides or both. Removing saline pressure and applying external compressive force on the knees did not affect the gaps. As this phenomenon cannot be explained with the conventional joint biomechanics, there is a need to revise the biomechanics of the knee joint, probably with the aid of the concepts laid in the theory of biotensegrity.

http://www.openaccessjournals.siftdesk.org/articles/pdf/The-Tibiofemoral-Joint-Gaps20151112000118.pdf

The Tibiofemoral Joint Gaps - An Arthroscopic Study

The effects of external resistance on the recruitment of trunk muscles in sagittal movements and the coactivation mechanism to maintain spinal stability were investigated using a simple computational model of iso-resistive spine sagittal movements. Neural excitation of muscles was attained based on inverse dynamics approach along with a stability-based optimisation. The trunk flexion and extension movements between 60° flexion and the upright posture against various resistance levels were simulated. Incorporation of the stability constraint in the optimisation algorithm required higher antagonistic activities for all resistance levels mostly close to the upright position. Extension movements showed higher coactivation with higher resistance, whereas flexion movements demonstrated lower coactivation indicating a greater stability demand in backward extension movements against higher resistance at the neighbourhood of the upright posture. Optimal extension profiles based on minimum jerk, work and power had ...

The effect of resistance level and stability demands on recruitment patterns and internal loading of spine in dynamic flexion and extension using a simple trunk model

A two-dimensional, biomechanical computer model was developed, using the software package Working Model1M, to simulate the postural control of seated individuals. Both able-bodied and spinal cord-injured subjects were represenied. The model incorporated active control of the upper body through full-state feedback. Specifically, a linear quadratic regulator scheme was implemented in the model. Nonlincaritics were included in the torque computations to mimic physiological constraints and disabiliiy. Interactions between the subject and the wheelchair were also included in the model. Simulation results were compared with those obtained from experiments in which the subjects had attempted to remain stable during the application of significant disturbance moments, similar to lhose experienced during braking in a vehicle. While subjects exhibited more complex control schemes, the model was able to simulate overall stability. Therefore, it is believed that the model could prove beneficial to future rese...

Simulation of the Seated Postural Stability of Healthy and Spinal Cord-Injured Subjects Using Optimal Feedback Control Methods.

Chapter 3 – Computational models for trunk trajectory planning and load distribution: a test-bed for studying various clinical adaptation and motor control strategies of low back pain patients

The goal of this study was to quantify the effect of experience and handrail presence on trunk muscle activities, rotational spinal stiffness and postural stability of construction workers. We evaluated spinal stability, and objective and subjective postural stability in 4 expert and 4 novice construction workers who were performing a manual task in a standing position on a scaffold, with and without a safety handrail. Center of pressure was computed using measurements taken with insole pressure transducers. Muscle activity was monitored using surface electrodes placed on 8 trunk muscles that predicted active trunk rotational stiffness. Standard deviations of the center of pressure, back muscle activity and spinal stiffness were greater in novices and in the absence of a handrail. We infer that the risk of a fall due to postural and spinal instability may be greater with a lower level of experience and in the absence of a safety handrail.

Mohamad Parnianpour

Papers

The Tibiofemoral Joint Gaps - An Arthroscopic Study

The effect of resistance level and stability demands on recruitment patterns and internal loading of spine in dynamic flexion and extension using a simple trunk model

Simulation of the Seated Postural Stability of Healthy and Spinal Cord-Injured Subjects Using Optimal Feedback Control Methods.

Chapter 3 – Computational models for trunk trajectory planning and load distribution: a test-bed for studying various clinical adaptation and motor control strategies of low back pain patients

The effects of experience and the presence of a scaffold handrail on postural and spinal stability in construction workers.