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Correction of drop foot in hemiplegic gait is achieved by electrical stimulation of the common peroneal nerve with a series of pulses at a fixed frequency. However, during normal gait, the electromyographic signals from the tibialis anterior muscle indicate that muscle force is not constant but varies during the swing phase. The application of double pulses for the correction of drop foot may enhance the gait by generating greater torque at the ankle and thereby increase the efficiency of the stimulation with reduced fatigue. A flexible controller has been designed around the Odstock Drop Foot Stimulator to deliver different profiles of pulses implementing doublets and optimum series. A peripheral interface controller (PIC) microcontroller with some external circuits has been designed and tested to accommodate six profiles. Preliminary results of the measurements from a normal subject seated in a multi-moment chair (an isometric torque measurement device) indicate that profiles containing doublets and optimum spaced pulses look favourable for clinical use.

Purpose: To review and characterise biomechanical approaches for the measurement of spasticity as one component of the upper motor neurone syndrome. Method: Systematic literature searches based on defined constructs and a four-step review process of approaches used or described to measure spasticity, its association with function or associated phenomena. Most approaches were limited to individual joints and therefore, to reflect this trend, references were grouped according to which body joint(s) were investigated or whether it addressed a functional activity. For each joint, references were further sub-divided into the types of measurement method described. Results: A database of 335 references was established for the review process. The knee, ankle and elbow joints were the most popular, perhaps reflecting the assumption that they are mono-planar in movement and therefore simpler to assess. Seven measurement methods were identified: five involving passive movement (manual, controlled displacement, controlled torque, gravitational and tendon tap) and two involving active movement (voluntary and functional). Generally, the equipment described was in an experimental stage and there was a lack of information on system properties, such as accuracy or reliability. Patient testing was either by cohort or case studies. The review also conveyed the myriad of interpretations of the concept of spasticity. Conclusions: Though biomechanical approaches provide quantitative data, the review highlighted several limitations that have prevented them being established as an appropriate method for clinical application to measure spasticity.

Purpose: To discuss the measurement of spasticity in the clinical and research environments, make recommendations based on the SPASM reviews of biomechanical, neurophysiological and clinical methods of measuring spasticity and indicate future developments of measurement tools. Method: Using the results of the systematic reviews of the biomechanical, neurophysiological and clinical approaches, methods were evaluated across three dimensions: (1) validity, reliability and sensitivity to change; (2) practical quality such as ease of use and (3) qualities specific to the measurement of spasticity, for example ability to be applied to different muscle groups. Methods were considered in terms of applicability to research and clinical applications. Results: A hierarchy of measurement approaches was identified from highly controlled and more objective (but unrelated to function) to ecologically valid, but less objective and subject to contamination from other variables. The lack of a precise definition of spasticity may account for the problem of developing a valid, reliable and sensitive method of measurement. The reviews have identified that some tests measure spasticity per se, some phenomena associated with spasticity or consequential to it and others the effect of spasticity on activity and participation and independence. Conclusions: Methods appropriate for use in research, particularly into the mechanism of spasticity did not satisfy the needs of the clinician and the need for an objective but clinically applicable tool was identified. A clinical assessment may need to generate more than one ‘value’ and should include evaluation of other components of the upper motor neurone syndrome. There is therefore a need for standardized protocols for ‘best practice’ in application of spasticity measurement tools and scales.

Johnson CA, Burridge JH, Strike PW, Wood DE, Swain ID. The effect of combined use of botulinum toxin type A and functional electric stimulation in the treatment of spastic drop foot after stroke: a preliminary investigation. Arch Phys Med Rehabil 2004;85:902–9. Objective To investigate the effect of combined botulinum toxin type A (BTX) and functional electric stimulation (FES) treatment on spastic drop foot in stroke. Design Nonblinded randomized controlled trial. Setting Hospitals. Participants Consecutive sample of 21 ambulant adults within 1 year after stroke with a spastic drop foot, of whom 18 completed the study. Interventions The treatment group received BTX injections (Dysport) on 1 occasion into the medial and lateral heads of the gastrocnemius (200U each) and tibialis posterior (400U each) muscles and FES, used on a daily basis for 16 weeks to assist walking. Both groups continued with physiotherapy at the same rate. Main outcome measures Walking speed, Physiological Cost Index, Modified Ashworth Scale, Rivermead Motor Assessment, and Medical Outcomes Study 36-Item Short-Form Health Survey. Results Walking speed increased over 12 weeks in both control ( P =.020) and treatment groups (nonstimulated, P =.004; stimulated, P =.042). The baseline corrected (analysis of covariance) increase in mean walking speed at 12 weeks, relative to controls, was .04m/s (95% confidence interval [CI], .003–.090) without stimulation, and .09m/s (95% CI, .031–.150) with stimulation. Conclusions Combined treatment effectively improved walking and function. A larger study is needed to quantify the treatment effect and to investigate its impact on quality of life.

The aim of this study was to implement a new approach to feedback control of unsupported standing and to evaluate it in tests with an intact and a paraplegic subject. In our setup, all joints above the ankles are braced and stabilizing torque at the ankle is generated by electrical stimulation of the plantarflexor muscles. A previous study showed that short periods of unsupported standing with a paraplegic subject could be achieved. In order to improve consistency and reliability and to prolong the duration of standing, we have implemented several modifications to the control strategy. These include a simplified control structure and a different controller design method. While the reliability of standing is mainly limited by the muscle characteristics such as reduced strength and progressive fatigue, the results presented here show that the new strategy allows much longer periods (up to several minutes) of unsupported standing in paraplegia.

We have measured some oscillatory properties of severe lower limb spasms experienced by a low-thoracic complete paraplegic during assisted standing. Electromyograms (EMG) were recorded from the leg muscles while the patient stood passively in a standing frame. The patient also stood using functional electrical stimulation (FES) while ground and handle reaction force vectors were measured together with EMG activity. During passive standing, spasms appeared simultaneously in all leg muscle groups on one side. The interval between spasms varied between 3 and 30 seconds. Within the spasms, there was a tendency of repetitive grouped discharge of motor units as well as a strong 10-Hz component in the EMG that was coherent across ipsilateral muscle groups. Thus, the spasms were inherently oscillatory. During FES-assisted standing, clinically similar spasms were observed. However, the interspasm interval became relatively fixed at around 16 seconds, which may indicate entraining of the spasm cycle by FES. There are similarities between this patient's spasms and the pathological motor activities seen in other movement disorders that may also be of spinal origin.

The objective was to inform sample size calculations for a full randomized controlled trial (RCT). The design included an RCT pilot trial with a 16 week study period, including a 4 week baseline phase. The subjects were adults within 1 year of first stroke, ambulant with a spastic dropped foot. Twenty-one participants were recruited from the stroke services of 4 centers. For intervention all participants received physiotherapy; the treatment group also received botulinum neurotoxin Type A (BoNTA) intramuscular injections to triceps surae (800 U Dysport) and functional electrical stimulation (FES) of the common peroneal nerve to assist walking. The main outcome measure was walking speed. The result was a significant upward trend in median walking speed for both the control (p = 0.02) and treatment groups (nonstimulated p = 0.004, stimulated p = 0.042). Trend lines were different in location (p = 0.04 and p = 0.009, respectively). In conclusion, there is evidence of an additional, beneficial effect of BoNTA and FES. Sufficient information has been gained on the variability of the primary outcome measure to inform sample size calculations for a full RCT to quantify the treatment effect with precision.

This study was concerned with individuals who were unable to effectively dorsiflex their ankle when walking, as a result of a lesion of the central nervous system (CNS). Indices that categorise and quantify different patterns of calf and anterior tibial muscle activation patterns during treadmill walking have been derived from a sample of fifteen individuals with established hemiplegia following stroke and twelve age-matched individuals without impairment. As subjects walked on a treadmill, force sensitive foot-switches under the heel and first metatarsal head allowed EMG signals from the calf and anterior tibial muscles to be related to phases of the gait cycle. Normal activation periods for each muscle group were identified as percentiles of the gait cycle and indices for muscle activation periods were derived using ratios of integrated EMG during selected periods. Indices were derived that identified statistically significant differences, between normal and hemiplegic subjects, in calf activation during both push-off phase (P

Study design: The bone mineral density (BMD) in 22 male subjects with complete lesion paraplegia sustained 1.8 to 27 years previously was measured. The measurements were used in screening each subject for a research programme investigating the restoration of standing using functional electrical stimulation (FES). Objectives: To assess the extent of bone loss in this group of subjects and correlation to age, time post-injury and level of lesion. Setting: District General Hospital in the UK. Methods: BMD was measured by dual energy X-ray absorptiometry (DEXA) in the lumbar spine and femoral neck and expressed as an indirect index to an age matched `normal' population. Fracture risk was described from this score using published data indicating that the risk increased with each standard deviation difference from the `normal' mean. Results: The bone density in the lumbar spine was better preserved than in the femoral neck. BMD in the lumbar spine was found to be greater than the mean from the age matched population in 57.1% of subjects. Bone loss at the femoral neck suggested that 81.8% of the subjects were at increased risk of fracture, but only 22.7% were at a high risk. No correlation was found between BMD at the lumbar spine or the femoral neck and age, lesion level or time post-injury. Conclusion: The study indicates that further investigation into baseline BMD values for the SCI population is required to improve information provided to patients and assessment of fracture risk on an individual basis. Sponsorship: U.K. Medical Research Council and the Wellcome Trust. Spinal Cord (2001) 39, 145–148.

To assess the clinical effectiveness of the Odstock dropped foot stimulator by analysis of its effect on physiological cost index (PCI) and speed of walking. This functional electrical stimulation (FES) device stimulates the common peroneal nerve during the swing phase of gait.A retrospective study of patients who had used the device for 4 1/2 months.One hundred fifty-one patients with a dropped foot resulting from an upper motor neuron lesion.A medical physics and biomedical engineering department of a district general hospital specializing in the clinical application of FES and a neurophysiotherapy department at a separate hospital.Changes in walking speed and effort of walking, as measured by PCI over a 10-meter course.There was a 92.7% compliance with treatment. Stroke patients showed a mean increase in walking speed of 27% (p.01) and reduction in PCI of 31% (p.01) with stimulation, and changes of 14% (p.01) and 19% (p.01), respectively, while not using the stimulator. Multiple sclerosis patients gained similar orthotic benefit but no "carry-over."The measured differences in walking with and without stimulation were statistically significant in the stroke and multiple sclerosis groups. In this study use of the stimulator improved walking. Those with stroke demonstrated a short-term "carry-over" effect.

Objective: To determine the perceived benefit, pattern and problems of use of the Odstock Dropped Foot Stimulator (ODFS) and the users' opinion of the service provided. Design: Questionnaire sent in a single mailshot to current and past users of the ODFS. Returns were sent anonymously. Setting: Outpatient-based clinical service. Subjects: One hundred and sixty-eight current and 123 past users with diagnoses of stroke (CVA), multiple sclerosis (MS), incomplete spinal cord injury (SCI), traumatic brain injury (TBI) and cerebral palsy (CP). Intervention: Functional electrical stimulation (FES) to correct dropped foot in subjects with an upper motor neuron lesion, using the ODFS. Main outcome measures: Purpose-designed questionnaire. Results:• Return rate 64% current users (mean duration of use 19.5 months) and 43% past users (mean duration of use 10.7 months). • Principal reason cited for using equipment was a reduction in the effort of walking. • Principal reasons identified for discontinuing were an improvement in mobility, electrode positioning difficulties and deteriorating mobility. • There were some problems with reliability of equipment. • Level of service provided was thought to be good. Conclusion: The ODFS was perceived by the users to be of considerable benefit. A comprehensive clinical follow-up service is essential to achieve the maximum continuing benefit from FES-based orthoses.

An apparatus has been developed that measures isometrically the 14 lower limb joint moments corresponding to the degrees of freedom of the hips, knees and ankles. This is the second of two papers describing the development of the multi-moment chair system (MMCS). It presents the overall design and changes that were implemented to compensate for problems. These were primarily to improve the accuracy of hip joint moments; a compromise between accuracy and practicalities, because of force-moment responses being measured at the ankles. All joint moment errors have been calculated to be of the order of a few newton metres. Since these represent errors of less than 10% when considering peak joint moment responses, this is considered sufficiently accurate for the proposed application. The MMCS is being used in a programme to investigate the restoration of lower limb functions, principally standing, in paraplegics by electrical stimulation of the lumbosacral anterior roots.

Summary Contemporary physiotherapy for neurologically impaired patients puts emphasis on the management of spasticity. A randomised controlled trial of the Odstock dropped foot stimulator (ODFS), a common peroneal stimulator used to correct drop-foot during walking, showed a reduction in spasticity of the quadriceps muscles in a sample of 32 chronic hemiplegic subjects. Both treatment (FES) and control groups received a course of ten physiotherapy sessions during the first four weeks of the trial period. The treatment group used the stimulator as part of the physiotherapy sessions and independently each day as they found useful. Both groups received the same amount of therapy contact time. The treatment group continued to use the stimulator for the 12-week period. Assessments also included measurement of walking speed and effort of walking, gait analysis and mobility and quality of life questionnaires. Results of these tests are not presented in this paper but are referred to in relation to changes in spasticity. Spasticity of the quadriceps muscles was measured using the Wartenberg pendulum test. Results showed that during the first four-week period both groups had a reduction in spasticity which was statistically significant in the control group; measured by both the relaxation index (p = 0.005) and the area beneath the curve (p = 0.036) and in the FES group only as the area beneath the curve (p = 0.028) At 12 weeks, reduction in spasticity in the control group was no longer statistically significant in either of these parameters, whereas in the treatment group reduction measured as area beneath the curve was statistically significant (p = 0.001). There was no statistically significant difference between the two groups. These results are discussed in relation to the subject of measurement of spasticity, the effect of physiotherapy on spasticity and observations made on changes in speed and effort of walking.

Systematic reviews are used to inform practice, and develop guidelines and protocols. A questionnaire to quantify the risk of bias in systematic reviews, the review paper assessment (RPA) tool, was developed and tested. A search of electronic databases provided a data set of review articles that were then independently reviewed by two assessors using the RPA. The inter-rater reliability was between moderate and good (κ scores 0.46-0.95). Many reviews did not describe the purpose in terms of population, intervention, comparator and outcome measure (i.e. PICO format), making inter-rater agreement on this question difficult. The RPA discriminated between high-quality reviews and those with a risk of bias (e.g. inadequate reporting of search terms, lack of independent reviewing or inclusion of non-randomized-controlled trials). The RPA questionnaire was revised to ensure that questions (on the basis of clarity of purpose, extent of search, independence of reviewers, randomized-controlled trial inclusion and availability of data) had dichotomous answers so that the positive responses scored one. The risk of bias increases as the score reduces.

Study design: Single subject pilot. Objectives: (i) To see whether strength and endurance for recreational cycling by functional electrical stimulation (FES) are possible following spinal cord injury (SCI). (ii) To develop the equipment for FES-cycling. Setting: England. Methods: Near-isometric or cycling exercise was performed by the incomplete SCI subject at home. Results: After training for an average of 21 min per day for 16 months, the stimulated muscles increased in size and the subject was able to cycle for 12 km on the level. Surprisingly, there was a substantial increase in the measured voluntary strength of the knee extensors and the subject reports improved leg function. Conclusion: FES-cycling may promote recovery after incomplete spinal cord injury. If so, it offers the possibility of being a convenient method for widespread use. Sponsorship: Spinal Injuries Unit, Royal National Orthopaedic Hospital, Stanmore.

The Odstock dropped foot stimulator (ODFS) is a foot switch controlled single channel neuromuscular stimulator for correction of dropped foot. Following a randomized controlled trial, the ODFS was recommended for use in the United Kingdom's National Health Service and a clinical service established. The patient performance was assessed by measurement of walking speed over 10 m, physiological cost index (PCI), and by questionnaire. After 4.5 months stroke patients (n = 111) showed a mean increase in walking speed of 27% and reduction in PCI of 31% with stimulation and changes of 14% and 19%, respectively, unassisted. Multiple sclerosis patients (n = 21) gained similar orthotic benefit but no carry over. The principal reason cited for using the equipment was that it reduced the effort of walking. The principal reasons identified for discontinuing were an improvement in mobility, electrode positioning difficulties, and deteriorating mobility. A comprehensive clinical follow-up service is essential to achieve the maximum continuing benefit from FES based orthosis.

Power distribution interconnects have become subject of stringent constraints on the electrical and mechanical performance as microprocessor speeds and their number of transistors keep rising. This increases the power/current draw dramatically both in magnitude and slew-rate. This paper describes a new power distribution interconnect device that addresses these needs.

Primary orthostatic tremor is characterized by 16-Hz motor activity that is coherent between muscles. It has been suggested that this tremor originates in the brain. This view is questioned by findings from a patient with complete paraplegia who experiences intermittent leg spasms at rest. The EMG activity within the spasms showed a 16-Hz component that was coherent between muscles unilaterally and bilaterally. This raises the possibility that the spinal cord could be the source of orthostatic tremor.

Three paraplegics have been implanted with stimulators of the lumbar anterior roots. Twelve roots were trapped in slots, each with three electrodes, a central cathode and two anodes, but the anodes in all the slots were connected together to reduce the number of wires. Cross-talk between roots was observed at lower levels than expected. Cross-talk was assessed from the ratio of the root's threshold to the threshold of the contralateral response (expected ratio: 72). Two hypothetical reasons for this low ratio were: that the cathode current was not equally shared by the anodes; or that the contralateral responses were reflex. Experiments showed that neither explanation was valid. The ratio of the contralateral to ipsilateral threshold for individual slots (K(1)) was sometimes low because the ipsilateral threshold was high. By taking the ratio of the lowest contralateral response to lowest ipsilateral response, for all roots in each subject (K(2)), the ratio should approach the theoretical value. However, for the two subjects with small slots, it was 7.9 and 15.3, much less than 72, suggesting that the original theory was incorrect. Approximate calculations of the activation function suggest that the reason may be that roots which run close to a slot, but not through it, may pass through a virtual anode region outside the ends of the slots, and that anodal break stimulation in those regions causes the cross-talk. Our estimate is that this cross-talk would be expected to occur at intensities above 5.3 times the cathodal threshold. If the roots are stimulated in pairs, below the levels of cross-talk, experimental results show that the moments obtained in response are additive to within 5%.

Using electrical stimulation of lower limb muscles to assist paraplegics to stand has many advantages over conventional passive standing techniques. However, stability and balance needs to be maintained, in response to muscle spasms and fatigue, postural changes and external perturbations, if the system is to be safe for a subject to take one hand off to perform tasks. The authors' system monitors the stand by measuring the knee angles and uses a closed-loop design, based on a PID (proportional-integral-derivative) type, to respond to deviations by adjusting the stimulation to the quadriceps. With this system the authors have stood 24 paraplegics, with 14 using it at home. The authors report their experience from one of their subjects who started retraining his quadriceps with electrical stimulation in October 1998 and first stood three months later. During sessions over the next three months, he was instructed in standing techniques and the closed-loop algorithm was implemented. The authors found that during standing, if the stimulation increased too quickly then strong stomach spasms resulted. This was improved by removing the controller's derivative term and low-level stimulation of the abdominal muscles as a daily exercise routine.

We investigated leg-powered cycling in a recumbent tricycle for a paraplegic using functional electrical stimulation (FES) with the lumbo-sacral anterior root stimulator implant (LARSI). A female complete T9 paraplegic had a stimulator for the anterior L2 to S2 spinal roots (bilaterally) implanted in 1994. She was provided with equipment for daily FES cycling exercise at home. The cycling controller applies a pattern of stimulation in each of 16 crank angle phases. A 7-bit shaft encoder measures the crank angle with adequate precision. Each pattern was originally chosen to give the greatest propulsive force in that position when there was no motion. However, dynamically, some reduction in co-contraction is needed; also the patterns are applied with a preset advance time. Maximal power is obtained with an advance of 250 ms, which compensates for muscle response delay and accommodates changes in cadence (from about 25 to 85 rpm). With this system, she has cycled 1.2 km at a time on gently undulating road. We found that spinal root stimulation gives sufficient control over the muscles in the legs to produce a fluid cycling gait. We propose that root stimulation for leg cycling exercise may be a practicable and valuable function for paraplegics following spinal cord injury.

An apparatus has been developed for making isometric measurements of the joint moments corresponding to the 14 degrees of freedom of the legs, in postures ranging between sitting and near full extension. The apparatus is called the multi-moment chair system (MMCS) and is described in the companion paper. This paper describes the most critical components of the MMCS, which are the six-axis transducers for measuring the force and moment components on the plantar-flexion axis of each ankle while the feet are laced into fixed shoes. The transducers are made of steel bars, on which strain gauges are mounted, joined by clamps. The design of the transducer and methods of calibration and error estimation are described. The RMS errors are less than 2 N for the forces and 1 Nm for the moments, but these may be correlated. A method for error reduction that compensates for the finite compliance of the transducer does not reduce the measured errors.

Objective: To measure the effect of the Odstock Dropped Foot Stimulator (ODFS), a common peroneal stimulator, on the effort and speed of walking. Design: A randomized controlled trial. Subjects: Hemiplegic patients who had suffered a single stroke at least six months prior to the start of the trial whose walking was impaired by a drop-foot. Interventions: The treatment, functional electrical stimulation (FES) group, used the stimulator and received a course of physiotherapy; the control group received physiotherapy alone. Main outcome measures: Changes in walking speed measured over 10 m and the effort of walking measured by physiological cost index (PCI). Results: Thirty-two subjects completed the trial, 16 in the FES group and 16 in the control group. Mean increase in walking speed between the beginning and end of the trial was 20.5% in the FES group (when the stimulator was used), and 5.2% in the control group. Improvement was also measured in PCI with a reduction of 24.9% in the FES group (when the stimulator was used) and 1 % in the control group. No improvement in these parameters was measured in the FES group when the stimulator was not used. Conclusion: Walking was statistically significantly improved when the ODFS was worn but no 'carry-over' was measured. Physiotherapy alone, in this group of subjects with established stroke, did not improve walking.

The authors' involvement in functional electrical stimulation (FES) began 13 years ago when they began investigation into the development of a standing system for complete paraplegics. This work was funded by the Medical Devices Agency of the Department of Health. During the course of this work the authors perceived that there were a number of incomplete paraplegics whose mobility could be improved by the provision of simple FES systems to dorsiflex the foot. At that time there did not appear to be a reliable, commercially available device in the UK. The subsequent grant further developed the stimulator, the Odstock Drop Foot Stimulator (ODFS) and established treatment protocols to improve walking function for patients with a variety of different neurological conditions such as CVA, MS and cerebral palsy as well as incomplete SCI. After the completion of the randomised controlled trial the authors obtain the approval of the South and West Development and Evaluation Committee in early 1996 which has made funding easier in certain areas. This trial showed that in the treatment group walking speed was increased by 21%, the effort involved in walking measured by the Physiological Cost index, PCI, was reduced by 25 %, that reduction in spasticity was more sustained and that patients anxiety and depression levels were reduced. All of these findings were statistically significant. The service has now been running for 5 years. The authors take referrals from both G.P.'s and Consultants and then apply to the patient's local Health Authority or to the G.P. if they are a member of a fund holding practice. (2 pages)

We previously analyzed UNOS data from patients (pts) having lung transplant (LTX) with the 4 most common diagnoses to identify risk factors (RF) for death after LTX, limiting the analysis to 11 yrs should be grouped with adults. Analysis of waitlist and post-LTX survival for other diagnoses resulted in 4 adult diagnostic groups and a 5th pediatric group. RF associated with increased risk of death while waitig were identified by another analysis. All pts having LTX from Jan.1/97 to Dec. 31/98 were studied. Group A(n=863): COPD and other obstructive diseases including sarcoid, mean PA 30, BOOP. Group E(n=59): pts

The U.S. Department of Energy (DOE) Headquarters EM-35, established a Performance Assessment Task Team (referred to as the Team) to integrate the activities of the sites that are preparing performance assessments (PAs) for disposal of new low-level waste, as required by Chapter III of DOE Order 5820.2A, {open_quotes}Low-Level Waste Management{close_quotes}. The intent of the Team is to achieve a degree of consistency among these PAs as the analyses proceed at the disposal sites. The Team`s purpose is to recommend policy and guidance to the DOE on issues that impact the PAs, including release scenarios and parameters, so that the approaches are as consistent as possible across the DOE complex. The Team has identified issues requiring attention and developed discussion papers for those issues. Some issues have been completed, and the recommendations are provided in this document. Other issues are still being discussed, and the status summaries are provided in this document. A major initiative was to establish a subteam to develop a set of test scenarios and parameters for benchmarking codes in use at the various sites. The activities of the Team are reported here through December 1993.

31/98 were studied. Group A(n 863): COPD and other obstructive diseases including sarcoid, mean PA 30. Group B(n 216): PPH and pulmonary vascular disease (1995-1998). Group C(n 294): CF, Group D(n 401): all pulmonary fibrosis, sarcoid, mean PA 30, BOOP. Group E(n 59): pts 12 years. To investigate if RF associated with increased risk of death on the waitlist were associated with risk of deatrh after LTX, group-specific Cox regression models were fitted with post LTX death as the outcome. Variables collected at listing or LTX were included in the models: demographic (age, height, weight, body mass index), hemodynamic (PA systolic, diastolic, mean, CO, wedge), pulmonary function (% FVC, FEV-1) or clinical (in hospital or ICU, functional status). One-year estimated survival was: Group A:81.6%, Group B:57.7%, Group C:81.7%, Group D:69%, (p 0.000). Death occurred in 466 pts. Group A:151 deaths, RF: increasing age, in ICU, CMV mismatch. Group B:104 deaths, RF: on ventilator. Group C:62 deaths, RF: previous transfusions, creatinine. Group D:136 deaths, RF: increasing PA systolic. Group E: only 13 deaths, RF incalculable. No variable associated with poor pulmonary function predicted increased risk of death after LTX. Hazard ratios for post-LTX death may be useful to develop a donor distribution algorithm that incorporates risk of death on the waiting list.

The challenge in the next decade for laboratory medicine is to accomplish major changes in organization to meet fiscal restraint and shortage of laboratory physicians. Collaborative networks, constructive use of black box devices, and the development of rapport between laboratories and their clients leading to cost effective utilization of limited resources, are some of the strategies that will maximize patient benefit.

Previous attempts to apply Halstead's software metrics to APL have led to inconsistent and counter-intuitive results. This work is a further investigation into the application of software metrics to APL to try to resolve some of the inconsistency. The effect of variations in the counting rules on values calculated for the software metrics was studied. These rules were used to analyze a set of programs from a previous study. In addition, a large number of APL programs from a university environment were analyzed. Evidence is presented that verifies that APL has a higher language level than any other common programming language previously studied. Counting monadic and dyadic uses of the same APL symbol as an instance of a different operator was found to have a significant effect on the language level calculated for APL. However, decomposing derived APL functions into separate operators did not seem to have a significant effect on language level.

The microstructure grain characteristics of single-layer CoCrTa films for perpendicular recording were correlated with the ability to support high density recording using thin film heads. Substrate temperature was identified as the critical sputtering parameter affecting grain. VSM measurements were found to be an unreliable indicator of read-write performance.

This study was undertaken to provide a numerical measure of the impact of operator actions on the shutdown of an HTGR plant similar to Fort St. Vrain during specified accident sequences. The study also provides a similar kind of measure for the impact of current procedures and practices during normal surveillance and calibration testing on the Fort St. Vrain Plant Protection System. It is concluded that the Fort St. Vrain shutdown and Plant Protection Systems appear to be relatively safe from any significant effects due to operator error during a high stress situation. However, the amount of public exposure during any credible accident can be significantly reduced by modifying administrative procedures and/or by training the operators to develop proper reflex actions during emergencies. It is concluded that operator errors during low stress surveillance and calibration exercises contribute negligibly to overall PPS failures at Fort St. Vrain as long as specified recovery factors are able to operate.

A Reliability and Safety Program plan outline has been prepared for the operational phase of a Waste Isolation Facility. The program includes major functions of risk assessment, technical support activities, quality assurance, operational safety, configuration monitoring, reliability analysis and support and coordination meetings. Detailed activity or task descriptions are included for each function. Activities are time-phased and presented in the PERT format for scheduling and interactions. Task descriptions include manloading, travel, and computer time estimates to provide data for future costing. The program outlined here will be used to provide guidance from a reliability and safety standpoint to design, procurement, construction, and operation of repositories for nuclear waste. These repositories are to be constructed under the National Waste Terminal Storage program under the direction of the Office of Waste Isolation, Union Carbide Corp. Nuclear Division.

The GO methodology has been successfully used to provide a comprehensive risk analysis of a spent fuel receiving and storage basin. As the facility was still in the conceptual design phase, the model was developed to emphasize material flows and functions rather than hardware. The multistate and interactive capability of GO was used to provide distributions of expected releases (instead of just single point values). Material flow through locations in the facility was modeled with release distributions determined for each section of the facility. Detailed risk plots are provided for some of the more significant potential releases. The expected values of the average annual potential releases from the facility are five orders of magnitude below the EPA proposed limits for the total fuel cycle of the 100 GWe of nuclear power that could be served by this facility.

Measurements of material bucklings for graphite uranium systems are summarized. A comprehensive listing and guide to the original data sources is provided. Complete information on physical and nuclear properties of the lattice and the geometry of the exponential assembly is included, along with some of the auxiliary data taken. The fuel sizes vary from 0.925 to 2.5 in. in diameter for five different fuel geometries. The lattice spacings vary from 4 3/16 to 15 in. Over 300 measurements of material buckling are included. (auth)

A system developed for the fast neutron-activation analysis of the oxygen content of metals has been tested comparatively with the conventional vacuum fusion and carrier-gas fusion techniques. The results of these tests indicate that neutron-activation analysis is much faster (the total analysis takes only 2 min or less), and more reliable than vacuum fusion and carrier-gas fusion methods because all oxygen present is analysed. Samples can be much larger than the 0.2–3 g commonly used for the fusion methods. Furthermore, the analysis is non-destructive—the same samples can be re-analysed as often as desired. The fast neutron-analysis system includes a 14-MeV neutron generator producing 1011 neutrons/sec, a dual-tube pneumatic transfer system, a 5 × 5 inch NaI(T1)crystal, a single-channel analyser, two scalers, and timers and switch-gear. A sample, in a polyethylene bottle, and a Lucite reference are irradiated simultaneously, after which the sample is returned to a detector for counting the 16N gammas from the 16O(n,p)16 N reaction. The reference is then counted in a second detector; the ratio of the sample counts to the reference counts is proportional to the oxygen content of the sample. Samples with oxygen contents from 0.002 to 0.1 % of oxygen have been analysed by neutron activation, then cut in several pieces for hot extraction analysis of the total sample.

The EPR spectrum of 2-adamantyl radical is reported; previously published spectra are shown to result from impurities. Possible mechanisms for the unusually high selectivity of damage to impurities included in the adamantane matrix are discussed.