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The objective of this paper is to present and validate an efficient guided wave absorber for increased sensitivity of structural health monitoring systems based on guided wave, and especially for inspection close to structure boundaries. Such an absorber would also help with systematic characterization of guided waves interaction with defects in aerospace structures. A complete numerical parametric study is undertaken using the power flow in the structure to determine the reflection and transmission coefficients and thus the dissipated energy by the absorber. Starting with the determination of the geometry and dimensions using Finite Element Modelling (FEM), and following with an investigation on the influence of the absorber's mechanical properties, a practical and efficient absorber is identified. The dimensions of the developed absorber are minimized to provide optimal results for frequencies ranging from 50kHz to 500kHz for an incident A0 mode. The resulting right triangle cross section absorber of Teflon has been machined and tested experimentally using a piezoelectric wave generator on one side of the absorber, and a tri-dimensional laser Doppler vibrometer (3D-LDV) to measure the transmitted wave on the other side. Using a spatial Fourier transform approach for the determination of the experimental reflection and transmission coefficients, the numerical results have been successfully validated. [ABSTRACT FROM AUTHOR]

Abstract: The Möbius transformation of probability cells in a multi-way contingency table is used to partition the Pearson chi-square test of mutual independence into A-dependence statistics. A similar partition is proposed for a universal and consistent test of serial independence in a stationary sequence of a categorical variable. The partition proposed can be adapted whether using estimated or theoretical marginal probabilities. With the aim of detecting a dependence of high order in a long sequence, A-dependence terms of the partition measuring increasing lagged dependences can be combined in a Box–Pierce type test of serial independence. A real data analysis of a nucleotides sequence using the Box–Pierce type test is provided. [Copyright &y& Elsevier]

The purpose of this study was to determine the effect of gender on changes in electromyographic (EMG) signal characteristics of the quadriceps muscles with increasing force and with fatigue. A total of fourteen healthy adults (seven men, seven women) participated in the study. Subjects had to perform isometric ramp contractions in knee extension with the force gradually increasing from 0 to 100% of the maximal voluntary contraction (MVC) in a 6-s period. Subjects then performed a fatigue task, consisting of a sustained maximum isometric knee extension contraction held until force decreased below 50% of the pre-fatigue MVC. Subjects also performed a single ramp contraction immediately after the fatigue task. The Root Mean Square (RMS) amplitude, mean power frequency (MPF) and median frequency (MF) of EMG signals obtained from the vastus lateralis, vastus medialis and rectus femoris were calculated at nine different force levels from the ramp contractions (10, 20, 30, 40, 50, 60, 70, 80 and 90% MVC), as well as every 5 s during the fatigue task. The main results were a more pronounced increase in EMG RMS amplitude for the three muscles and in MPF for the VL muscle with force in men compared with women. No significant effect of gender was found with regards to fatigue. These observations most likely reflect a moderately greater type II fiber content and/or area in the VL muscle of men compared to that of women. [Copyright &y& Elsevier]

Abstract: Liver transplantation is associated with a number of neurological complications. We herein report a case of chronic inflammatory demyelinating polyneuropathy associated with the use of sirolimus-based immunosuppression. The patient was treated by converting the immunosuppression from sirolimus to cyclosporine and by a short course of oral steroids. Following this, we observed almost complete clinical and electrophysiologic resolution of this syndrome. We believe that this is the first described case of such a complication occurring in association with sirolimus. This immunosuppressive agent can, therefore, lead to neurological complications similar to the ones that have been observed with calcineurin inhibitors. [Copyright &y& Elsevier]

• Size distribution of the run-of-mine ore was measured in a rock quarry with a 3D free fall rock-sizing sensor. • Free fall speed of the rock is measured from the spectral analysis of a line-scan image of the rock flow. • 3D free fall rock-sizing sensor measures the volume and characterized the shape of rock particles. • Volumetric rock size distribution was coherent to size distribution measured by sieving and unbiased. The energy efficiency of the grinding process is less than 1%, and it consumes about 40% of the energy in a typical open-pit mine operation (CIPEC, 2005). One of the causes of this low energy efficiency is the high variability of the run-of-mine ore hardness and size distribution, which must be measured accurately in order to develop process control strategies that will minimise their impact on mill efficiency. On-line rock hardness sensors are still unavailable and 2D rock size sensors show important limitations under uncontrolled outside lighting conditions. A rock hardness sensor based on primary crusher data analysis has provided interesting results but it requires a more accurate size measurement of the run-of-mine ore, which is a key information for evaluating the reduction ratio and compute the rock hardness index accordingly. Recently, laser 3D profiler has been identified as an interesting technology for measuring rock size distribution over a conveyor belt and they are now commercially available. This paper discusses the extension of this application to the measurement of ore size distribution as it is dumped into the primary crusher. The objectives are (1) to provide an accurate evaluation of the reduction ratio at the primary crushing stage and to allow the development of a rock hardness sensor, (2) to quantify the quality of the blast before any crushing size reduction, and (3) to address the measurement error of the fines associated with the conveyor belt system. A first prototype of the 3D rock sizing technology was evaluated in a rock quarry environment. The prototype was then improved based on the findings. The most important upgrade is a free fall rock- speed evaluation technique, which is based on the spectral analysis of a line-scan image of the rock flow. Despite some accuracy enhancement over existing 2D technologies, the 3D free fall rock-sizing sensor is still, in its industrial arrangement, limited to the measurement of a surface based rock size distribution. This limitation is due to the intrinsic depth sampling error of the 3D sensor, which sees only the front layer of the rock flow and, as a result, overestimates the percentage of coarser rocks. A full volumetric 3D free fall rock-sizing sensor was built in parallel at laboratory scale to overcome this limitation: it measures the entire volume of each piece of rock as they fall in a monolayer flow between two facing laser scanners. The resulting volumetric rock size distribution was found to be coherent to the size distribution measured by sieving, unbiased and, therefore, more accurate than any surface based rock size distribution. The volumetric 3D free fall rock-sizing sensor is proposed for upgrading commercial 2D imaging technologies, which are now used as an alternative to rock sieving in laboratory. A few industrial application scenarios, including its potential integration into an ore-sorting process, are also being investigated. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess differences in fatigue-related changes in variables related to structures within the neuromuscular system, between the dominant and non-dominant elbow flexor muscles of right-handed individuals. Two experimental sessions were performed on the right arm and one on the left arm. For each session, maximum voluntary torque, level of voluntary activation, M-wave amplitude, twitch/train or twitch/doublet torque ratio and EMG median frequency were obtained before and up to 20 min after a sustained maximum isometric fatigue task. Our main results were: 1) reproducible fatigue-induced changes in all variables of interest between the two sessions performed with the right arm, 2) significantly greater failure in voluntary activation and neuromuscular propagation with sustained activity for the non-dominant compared with dominant side, and 3) no effect of dominance on MVC torque, endurance time, and fatigue-induced changes in EMG median frequency and elicited torques. These results suggest that the preferential use of elbow flexor muscles with the dominant arm leads to more fatigue resistance in certain structures/mechanisms of the neuromuscular system, but not in others. [Copyright &y& Elsevier]

Abstract: Recruitment patterns of the superficial and deep abdominal muscles have been well documented in the general population, but not in a group of individuals with a chronic cough, such as individuals with cystic fibrosis (CF), which may alter the recruitment patterns between the abdominal muscles. Therefore the two objectives of this study were (1) to identify whether recruitment of the superficial and deep abdominal muscles during abdominal hollowing (AH) and unilateral leg load (ULL) tasks differed between individuals with CF and a non-CF control group (C); and (2) to compare the muscle activity between the superficial and deep abdominal muscles across these tasks. Methods: Twenty-eight participants (14 with CF and 14 controls) performed (i) AH in supine at three target pressures of a pressure biofeedback unit (PBU) and (ii) a right-sided ULL. Surface electromyography (EMG) of the abdominal muscles was recorded and the amplitude of the signal was normalized to a maximum value (% max). Results: A 3-way repeated measures ANOVA showed a muscle×task interaction during the AH, but no between group differences. Bonferonni post hoc tests on pooled data showed the deep abdominal muscles to be significantly more active than the superficial muscles. A 2-way repeated measure ANOVA indicated no group differences during the ULL. Discussion: The results of this study demonstrate that adults with stable CF do not recruit their abdominal muscles differently from healthy control subjects during the AH and the ULL tasks. This suggests that coughing is not a risk factor for developing abdominal muscles imbalances in adults with cystic fibrosis. [Copyright &y& Elsevier]