Artificial exomuscle investigations for applications--metal hydride.

In pursuing the development of bionic devices, Victhom identified a need for technologies that could replace current motorized systems and be better integrated into the human body motion. The actuators used to obtain large displacements are noisy, heavy, and do not adequately reproduce human muscle behavior. Subsequently, a project at Victhom was devoted to the development of active materials to obtain an artificial exomuscle actuator. An exhaustive literature review was done at Victhom to identify promising active materials for the development of artificial muscles. According to this review, metal hydrides were identified as a promising technology for artificial muscle development. Victhom's investigations focused on determining metal hydride actuator potential in the context of bionics technology. Based on metal hydride properties and artificial muscle requirements such as force, displacement and rise time, an exomuscle was built. In addition, a finite element model, including heat and mass transfer in the metal hydride, was developed and implemented in FEMLAB software.

A neural network model for reconstructing EMG signals from eight shoulder muscles: consequences for rehabilitation robotics and biofeedback.

This paper demonstrates the ability of a fully connected feed forward neural network (FFNN) using the backpropagation training algorithm to predict the electromyography (EMG) signal from eight muscles of the shoulder for both exercises not used for training and EMG signals from subjects not used for training. The network showed a good predictive ability for subjects not used for training (r(2) between 0.33 and 0.84) and for activities not used for training (r(2) between 0.56 and 0.89). This may have applications for patients, physical therapists and doctors to monitor patient performance by reviewing the level of agreement between the patient EMG and the predicted EMG. Coupled with traditional methods of evaluation, EMG can provide an excellent measure of how well a patient has responded or is responding to treatment. Incorporating robotic technology could facilitate the use of EMG as an input to an intelligent decision making algorithm used to increase or decrease the level of difficulty according to patient performance.

Calibration of a Hall effect displacement measurement system for complex motion analysis using a neural network.

Biomechanics studies often require the analysis of position and orientation. Although a variety of transducer and camera systems can be utilized, a common inexpensive alternative is the Hall effect sensor. Hall effect sensors have been used extensively for one-dimensional position analysis but their non-linear behavior and cross-talk effects make them difficult to calibrate for effective and accurate two- and three-dimensional position and orientation analysis. The aim of this study was to develop and calibrate a displacement measurement system for a hydraulic-actuation joystick used for repetitive motion analysis of heavy equipment operators. The system utilizes an array of four Hall effect sensors that are all active during any joystick movement. This built-in redundancy allows the calibration to utilize fully connected feed forward neural networks in conjunction with a Microscribe 3D digitizer. A fully connected feed forward neural network with one hidden layer containing five neurons was developed. Results indicate that the ability of the neural network to accurately predict the x, y and z coordinates of the joystick handle was good with r(2) values of 0.98 and higher. The calibration technique was found to be equally as accurate when used on data collected 5 days after the initial calibration, indicating the system is robust and stable enough to not require calibration every time the joystick is used. This calibration system allowed an infinite number of joystick orientations and positions to be found within the range of joystick motion.

The reovirus project: an application of distributed visualization.

This paper describes a distributed visualization of the operation of a reovirus. This visualization allows several groups of users at different locations to view how the virus behaves in normal and cancer cells. The users at each location can interact with the visualization and the other users. The techniques used to produce this visualization include the reduction of geometrical complexity, user representation and interaction with the visualization. Future work includes improving the explanations of the reovirus and providing users with different views of the animation highlighting various aspects of the virus's behaviour.

Laryngotracheal morphology of Afro-Madagascan geckos: a comparative survey.

The structural variation of the gekkonid larynx and trachea is examined within a representative subset of 17 species of Afro-Madagascan gekkonines to determine if there are underlying morphological correlates of vocalization. The documented morphology is compared to that of the tokay (Gekko gecko), which has previously been described. Data were obtained from gross anatomical observations, scanning electron microscopy, histological examinations and computer-generated, three-dimensional, skeletal reconstructions. Although there is limited variation among most Afro-Malagasy gekkonids, the larynges of Ptenopus garrulus and Uroplatus fimbriatus exhibit marked degrees of differentiation, suggesting that laryngeal and tracheal morphology may account for the documented vocal variability of gekkonid lizards. Cladistic analyses indicated that parallel adaptive trends characterize the laryngeal morphology of the examined taxa. Alternate designs and refinements to a model of gekkonid phonation are presented, and the evolution of acoustic communication in the Gekkonidae is considered.

An unusual presentation of emphysematous cystitis.

Emphysematous cystitis is a rare disorder most commonly seen in women and associated with urinary tract infections and poorly controlled diabetes mellitus. We report the case of a 76-year-old woman who presented with diarrhea and abdominal discomfort, and emphysematous cystitis was revealed on the abdominal X-ray series. This case is unique in that the patient had no evidence of urinary tract infection, diabetes, or recent instrumentation. As the patient was treated for emphysematous cystitis (bladder irrigation and intravenous antibiotics), the diarrhea rapidly resolved and the radiographic abnormalities of the emphysematous cystitis also resolved. This may suggest a causal relationship, although a specific mechanism is unknown.

Morphological modeling via isosurfacing: the laryngeal skeleton of gekkonid lizards as a test case.

A novel technique for modeling microscopic anatomical structures in three dimensions was developed as part of a survey of gekkonid laryngeal skeletal morphology (Reptilia: Gekkonidae). Excised larynges were transversely sectioned at 10 microns and stained using standard procedures. With a projection microscope, outline drawings of the sectioned laryngeal cartilages were made at regular intervals, depending on the rate and degree of structural change observed while sampling. The drawing set was digitized with a flatbed scanner, and aligned using 'NIH Image' for Macintosh computers. Physical connectivity between successive outlines was provided by inserting one or more artificial slices between those that had been digitized, and draping a skin of rendered contours over all of the interstitial spaces present in the template. The Application Visualization System, a general purpose visualization package for UNIX-based computer systems, was used to visualize and render the resulting 'isosurfaces', which appear as solid three-dimensional objects and can be viewed from any perspective. Since isosurfaced reconstructions can be based on as little as 20% of the cross-sections available, this procedure has the potential to be a valuable research tool for future morphological work at the microscopic level.

Evaluation of interceed(TC7) for reduction of postoperative adhesions in rabbits.

OBJECTIVE: To evaluate the effectiveness of Interceed(TC7) (Johnson and Johnson, New Brunswick, NJ) in the prevention of postoperative adhesions in a rabbit uterine horn model. Interceed(TC7) was tested in the presence and absence of absorbable suture. DESIGN, SETTING, PARTICIPANTS: Forty-one New Zealand white rabbits had lesions created on bilateral uterine horns at laparotomy. Lesions were randomly allocated to treatment with Interceed(TC7) or control. The effect of Interceed(TC7) was evaluated on sutured lesions (4-0 polyglactin 910; Ethicon, Inc., Somerville, NJ) as well as on open cut lesions (no sutures applied). MAIN OUTCOME MEASURES: Adhesion formation, using a grading system ranging from 0 to 3. RESULTS: Interceed(TC7)-treated animals in the sutured group (average adhesion score +/- SD = 2.15 +/- 1.3) did not differ from controls (average score +/- SD = 2.35 +/- 0.93) in adhesion formation, P = 0.47. Rabbits with open cut lesions treated with Interceed(TC7) (average adhesion score +/- SD = 1.89 +/- 1.1) did not differ from control animals (average score +/- SD = 1.83 +/- 1.2), P = 0.88. CONCLUSIONS: Interceed(TC7) was not an effective adhesioprophylactic agent in the presence or absence of nonreactive absorbable suture.

A comparison of TC7 and 32% dextran 70 for prevention of postoperative adhesions in hamsters.

Prevention of postoperative adhesion formation has received considerable attention by infertility specialists. Barrier methods and hydroflotation solutions are currently used for adhesion prevention. The present study compared the efficacy of TC7 and 32% dextran 70 in a hamster model. At laparotomy, 90 golden hamsters had a lesion created on the left uterine horn and repaired with absorbable suture. The first experiment used 3-0 chromic catgut suture in 43 hamsters; the second experiment used 5-0 polyglactin 910 suture in 47 hamsters. The animals were randomly divided into a control group (N = 25) which received no treatment, a TC7-treated group (N = 33), and a 32% dextran 70-treated group (N = 32). The animals were sacrificed between 10-14 days after laparotomy and adhesions were graded (0 = no adhesions; 3 = severe adhesions). TC7 had average adhesion scores of 1.91 for chromic catgut and 2.25 for polyglactin 910; 32% dextran 70 had average adhesion scores of 1.53 and 2.00, respectively. These scores were not different from the control average adhesion score of 1.80 for both chromic catgut and polyglactin 910. We conclude that TC7 and 32% dextran 70 do not appear to be effective agents for preventing postoperative adhesions in this animal model.

Effect of posture on arterial baroreflex control of heart rate in humans.

Altered baroreflex function may contribute to the cardiovascular changes associated with weightlessness. Since central blood volume (CBV) increases during simulated weightlessness we have examined the possibility that acute changes in CBV may modify baroreceptor function. We used graded head-up tilt (HUT) and head-down tilt (HDT) to induce changes in CBV, and neck suction to stimulate carotid baroreceptors, in 6 subjects. The increase in pulse interval induced by a negative pressure of 8.2 kPa (62 mm Hg) imposed for 10 s while supine was compared with the increase while tilted for 8 min at +/- 15 degrees, +/- 30 degrees and +/- 45 degrees. During HDT at 15 degrees the pulse interval over the first 5 cardiac cycles following suction onset was 51 +/- (SEM) 18 ms longer (p less than 0.05), at 30 degrees it was 61 +/- 20 ms longer (p less than 0.05), and at 45 degrees it was 74 +/- 35 ms longer (p less than 0.01), compared with supine. During HUT at 15 degrees the pulse interval was 25 +/- 9 ms shorter (p less than 0.05) than when supine, but was not significantly different at 30 degrees and 45 degrees. These responses occurred independently of changes in brachial blood pressure. Attenuation was also observed after 5 min (56 +/- 17 ms; less than 0.05), and after 40 min (25 +/- 9 ms; p less than 0.05) of 60 degrees HUT compared with supine. We conclude that posture does modify arterial baroreflex control of heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)