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PubMed1976

Untrained paraprofessionals' verbal helping behavior. Description and implications for training.

The verbal behavior of untrained paraprofessionals in simulated initial helping interactions was studied. Taped interviews conducted by 131 helpers-in-training were evaluated on the Helping Skills Verbal Response System, a category system consisting of continuing, leading, and self-referent responses. Helpers were found to vary considerably in number and types of responses given. Leading responses were twice as frequent as continuing responses. The most often used response was the closed question. Few responses focusing on helpees' feelings were given. The implications for training were discussed in terms of the facilitative role of helpers in initial helping interactions.

Adult↗

PubMed2001

[Virtual reality in ophthalmological education].

We present a computer-based medical training workstation for the simulation of intraocular eye surgery. The surgeon manipulates two original instruments inside a mechanical model of the eye. The instrument positions are tracked by CCD cameras and monitored by a PC which renders the scenery using a computer-graphic model of the eye and the instruments. The simulator incorporates a model of the operation table, a mechanical eye, three CCD cameras for the position tracking, the stereo display, and a computer. The three cameras are mounted under the operation table from where they can observe the interior of the mechanical eye. Using small markers the cameras recognize the instruments and the eye. Their position and orientation in space is determined by stereoscopic back projection. The simulation runs with more than 20 frames per second and provides a realistic impression of the surgery. It includes the cold light source which can be moved inside the eye and the shadow of the instruments on the retina which is important for navigational purposes.

Computer Graphics↗

PubMed2001

Automated high-frequency posture sampling for ergonomic assessment of laparoscopic surgery.

BACKGROUND: Despite widespread acknowledgement that strain injuries do occur to surgeons, ergonomic assessments in minimally invasive surgery are comparatively rare. Current assessment techniques rely on labor-intensive manual recording techniques, so there is a need for an automated system. METHODS: We used an optoelectronic measurement system to make postural measurements at frequencies of ~5 Hz and then converted these measurements to ergonomic stress scores using a modified Rapid Upper Limb Assessment (RULA) method. RESULTS: We successfully recorded postures at least once per second during 96% of the time the surgeon was performing tissue manipulation tasks. We found that the ergonomic stress scores were comparatively high throughout the procedure, particularly for the wrist. CONCLUSION: An automated high-frequency postural measurement system is feasible for making ergonomic assessments in an intraoperative setting. Such a system will also be a critical component in validating surgical simulations for use in training and credentialing surgeons and in designing and evaluating equipment.

Biomechanical Phenomena↗

PubMed1993

Answering the connectionist challenge: a symbolic model of learning the past tenses of English verbs.

Supporters of eliminative connectionism have argued for a pattern association-based explanation of language learning and language processing. They deny that explicit rules and symbolic representations play any role in language processing and cognition in general. Their argument is based to a large extent on two artificial neural network (ANN) models that are claimed to be able to learn the past tenses of English verbs (Rumelhart & McClelland, 1986, Parallel distributed processing, Vol. 2, Cambridge, MA: MIT Press; MacWhinney & Leinbach, 1991, Cognition, 40, 121-157). In this article we critically review Rumelhart and McClelland's as well as MacWhinney and Leinbach's ANN models and conclude that they do not succeed in the assigned task of learning the past tenses of English verbs. In order to answer their challenge to the symbolic processing approach, we present our symbolic pattern associator (SPA)-a general-purpose pattern associator that can learn to associate arbitrary discrete patterns. We carried out several experiments with the SPA using the same set of verbs that was used in MacWhinney and Leinbach's simulation with more realistic training and testing procedures. The SPA outperformed the connectionist models by a wide margin in the accuracy of learning, and successful inductive generalizations to unseen verbs. Our SPA has very natural and psychologically realistic explanations to many psychological effects such as U-shaped learning curve, and is much closer to human subjects in predicting past tense of the pseudo-verbs. In contrast to ANNs, whose internal representations are entirely opaque, the SPA can represent the acquired knowledge in the form of production rules that allow for further higher-level processing and integration, resulting in linguistically realistic associative templates for irregular verbs and production rules for regular verbs. In the light of these findings, we conclude that eliminative connectionists' vision of cognition as simple pattern association and pattern recognition without symbolic representation is inadequate. Pattern association as such does not imply rule-less or cue-based models of language acquisition or of human learning in general.

Cognition↗

PubMed1975

An EEG simulator-a means of objective clinical interpretation of EEG.

In 1969 Zetterberg presented a method for describing the spectral properties of an EEG signal, starting from the assumption that the signal is essentially stationary during the analysis epoch. The method involves determination of the parameters for a model consisting of a lenear filter with the ability to produce a signal with the same spectral properties as the EEG signal. Zetterberg and Ahlin described in 1975 an analogue simulator based on this model theory. With this simulator it is possible to reproduce practically all types of stationary, as well as a number of non-stationary, EEG signals. We have used this simulator to demonstrate in an illustrative manner the relation between the properties of a signal in the spectral domain and in the time domain. We have also endeavoured to anser the question: if one starts from the frequency spectrum, what does the EEG signal corresponding to this spectrum look like? We also draw attention to the usefulness of the simulator in connection with training and as an instrument for testing computer and other systems of EEG analysis.

Computers↗

PubMed1992

Effects of exercise and inactivity on intravascular volume and cardiovascular control mechanisms.

Exercise, inactivity and confinement have been used as effective tools to assess the contributions of vascular volume and baroreflexes to orthostatic hypotension associated with exposure to microgravity. Prolonged exposure to bedrest, physical inactivity, or wheelchair confinement removes baroreceptor unloading caused by regular upright standing and induces attenuation of cardiovascular baroreflex responses. The magnitude of reduced baroreflex sensitivity following bedrest or wheelchair confinement is related to the degree of orthostatic hypotension. Reduction in vascular volume caused by bedrest or progressive hypovolemia does not affect carotid-cardiac baroreflex function. In contrast, intense exercise that increases arterial baroreceptor loading causes an acute increase in carotid baroreceptor sensitivity and has been associated with enhanced orthostatic stability following exposure to simulated microgravity. Endurance exercise training designed to enhance orthostatic stability was associated with increased blood volume and vasoconstrictive reserve, but no change in the carotid baroreflex response. Therefore, using models of exercise, inactivity and confinement, integrated and redundant roles for vascular volume and cardiovascular baroreflexes have been demonstrated as probable underlying mechanisms that contribute independently to the development of orthostatic hypotension following spaceflight. These data suggest that loading of arterial baroreceptors may be necessary to maintain baroreflex function.

Animals↗

PubMed1994

Principle approaches to selection of the short-arm centrifuge regimens for extended space flight.

Eight +Gz regimens on the SAC varying in their values (within 0.8 to 1.6 G), exposures, schedules, etc. were analyzed. Some regimens were combined with water-salt supplements (WSS) or veloergometer training (VE). Weightlessness was simulated by 3- to 28-day water immersion. +3 Gz loads on the centrifuge with the radius of 7.5 m were applied prior to and post immersion. Regimens for human runs on the SAC as a novel, perspective countermeasure for interplanetary expeditions should be selected with due regard of the human tolerance, their efficiency, and subsequent verification and specification in orbital flights. These approaches showed that 3 days of exposure to 1.2 G combined with WSS and 6 days of exposure to G-loads from 0.8 to 1.6 G together with VE were most optimal.

Acceleration↗

PubMed2005

Multi-tasking in practice: coordinated activities in the computer supported doctor-patient consultation.

UNLABELLED: The paper provides detailed descriptions of general practitioners (GPs') interactions, both with their computers and their patients, with the aim of facilitating the detailed understanding of how GPs use their computers while in consultation with patients. The focus is on the coordinated activities of the doctor and patient and the multitasking that is required during consultation. The data consists of primary care doctor-patient consultations for asthma and angina where clinical scenarios, supported by dummy electronic and paper records for use by the doctor, were played out. Although not 'naturally occurring', the mock scenario is a traditional medical training technique. OBJECTIVE AND METHODS: This paper describes and demonstrates a data transcription methodology, involving seven discrete levels of activities, developed to account for the intricate multitasking that occurs in a GP consultation. The transcription method, developed to support the evaluation of a prototype medical prescribing decision support system (Prodigy) for use by general practitioners in consultation with patients, builds on data description techniques from conversation analysis (CA) and video analysis (VA). CONCLUSIONS: It is suggested that the methodology described could also be applicable to other scenarios involving the observation of human-computer-human interaction.

Decision Support Systems, Clinical↗

PubMed2006

Comparison of global positioning and computer-based tracking systems for measuring player movement distance during Australian football.

Sports scientists require a thorough understanding of the energy demands of sports and physical activities so that optimal training strategies and game simulations can be constructed. A range of techniques has been used to both directly assess and estimate the physiological and biochemical changes during competition. A fundamental approach to understanding the contribution of the energy systems in physical activity has involved the use of time-motion studies. A number of tools have been used from simple pen and paper methods, the use of video recordings, to sophisticated electronic tracking devices. Depending on the sport, there may be difficulties in using electronic tracking devices because of concerns of player safety. This paper assesses two methods currently used to measure player movement patterns during competition: (1) global positioning technology (GPS) and (2) a computer-based tracking (CBT) system that relies on a calibrated miniaturised playing field and mechanical movements of the tracker. A range of ways was used to determine the validity and reliability of these methods for tracking Australian footballers for distance covered during games. Comparisons were also made between these methods. The results indicate distances measured using CBT overestimated the actual values (measured with a calibrated trundle wheel) by an average of about 5.8%. The GPS system overestimated the actual values by about 4.8%. Distances measured using CBT in experienced hands were as accurate as the GPS technology. Both systems showed relatively small errors in true distances.

Australia↗

PubMed2003

Incorporating robotics into an open-heart program.

The above described clinical series show that after a careful and thorough training program and stepwise introduction of surgical telemanipulation systems, application of telemanipulations is safe and shows acceptable results. Still, OR times are longer than for conventional procedures, and the operation is demanding, and expensive. The main shortcoming is that the procedure is only suitable for a highly selected patient population. However, despite all the clinical experience gathered in various centers, this technique is still evolving and in its beginning. There are some very promising developments that will improve the benefit of telemanipulators. For the first time, the separation of the surgeon from the surgical field facilitates training of surgeons on simulators. This might lead to a higher standard of surgical performance. Progress in sensor technology will make tactile-force feedback available, and new 3 D-visualization systems are designed to provide a better depth perception and higher resolution of the endoscopic image. Virtual stabilizing systems will enable robotic systems to operate on a virtual arrested heart without the need for CPB or mechanical stabilizers. These and other research topics summarized under the term augmented reality will enhance the natural senses and abilities of the surgeon. More and more, automatization will find its way into the OR. Preoperatively collected data about the patient's anatomy will be used to create safety margins, the robotic system will allow for the surgeon's movements, and instruments will be able to find their way to the surgical site without remote control. Because a stepwise approach has led to the clinical results that we and others have now achieved, it is the basis for further step-by-step development of the application of telemanipulation systems in coronary artery bypass grafting, and possibly other endoscopic procedures in cardiac surgery.

Animals↗

PubMed2001

Advances in camera, video, and imaging technologies in laparoscopy.

The introduction of technological advances, such as HDTV, three-dimensional laparoscopy, and further miniaturization of high-resolution digital video cameras, will allow significantly enhanced opportunities for laparoscopic surgical proficiency and further broadening of laparoscopic applications in urology. These enhancements, coupled with the recent advances in telemedicine and surgical simulation, will improve laparoscopic training and skill acquisition, decrease operative times and costs, minimize morbidity, and improve overall patient care.

Equipment Design↗

PubMed1999

The importance of fluorescein angiography in planning laser treatment of diabetic macular edema.

OBJECTIVE: To test the hypothesis that pretreatment fluorescein angiography (FA) is not necessary for effective laser treatment of patients with clinically significant diabetic macular edema (CSME). DESIGN: Prospective, randomized, controlled treatment simulation. PARTICIPANTS: Six fellowship trained retina specialists. INTERVENTION: The authors compared the ability of four retina specialists (observers) to plan laser treatment with and without the use of FA. One hundred consecutive cases of CSME were selected, each case consisting of a stereo pair of color photographs and a corresponding fluorescein angiogram. These cases were first read by two retina specialists who reached consensus on a treatment plan for each case (standard map). Each of the 4 observers reviewed 50 of these cases on 2 occasions and plotted 2 sets of treatment maps, 1 set created with and 1 without the aid of FA. Each observer's 100 treatment maps were graded for accuracy by comparing them to the corresponding standard maps. The role of FA in improving the accuracy of treatment maps was evaluated using logistic regression analysis to control for different observers, different cases, and different posterior pole characteristics. MAIN OUTCOME MEASURES: Accuracy was defined as the proportion of standard treatment correctly treated by the observer. RESULTS: For the observers as a group, the use of FA improved treatment planning accuracy from 49% to 54.5% (P = 0.02); however, there was significant interobserver variation in performance (P < 0.001). Treatment planning accuracy without and with FA was as follows: observer 1, 40.8% and 40.2%; observer 2, 49.8% and 72%; observer 3, 56.1% and 59.5%; and observer 4, 49.2% and 46.4%. CONCLUSION: The use of FA improves the accuracy of treatment planning for CSME. The authors' study supports the use of FA in laser treatment of patients with CSME.

Diabetic Retinopathy↗

PubMed1996

Measure and statistical test for cross-correlation between paired neuronal spike trains with small sample size.

Recent development of multi-unit recording techniques such as optical recording and multi-electrode arrays makes it possible to record neuronal activities from tens or hundreds of neurons simultaneously. To analyze functional connections between these neurons, cross-correlation analysis has been most commonly applied to the hundreds to thousands of pairs of these neurons. However, conventional cross-correlation data needs statistical tests for significance especially when the sample size of recorded spike trains is small. Here, a multiple hypergeometric model based on a transformation of the cross-correlogram data to a 2 x J table has been suggested. The exact p value for significance can be obtained by the generalized Fisher's method with small sample size and a cross-correlation coefficient for the strength of cross-correlation can be obtained based on the R-square analogue for nominal data. For large sample size, chi 2 test can be applied based on the same transformation. Examples of real spike train data set and simulation show that the methods are applicable to the data of multi-unit activity with only tens of spikes. These methods are especially useful when thousands of cross-correlograms need to be screened quickly and automatically.

Action Potentials↗

PubMed1984

Functional characteristics of retrograde conduction in a pacing model of "endless loop tachycardia".

A pacing model was designed that stimulated "endless loop tachycardia," a complication found in the new generation of DDD (atrioventricular [AV] universal) pacemakers. The functional characteristics of the train of ventricular impulses simulating endless loop tachycardia were studied during both AV sequential pacing and basic ventricular drive. AV sequential pacing, by causing a decrease in ventriculoatrial (VA) conduction time of the first beat of the endless loop tachycardia, was associated with a decrease in the cycle length at which VA block occurred in 9 of 12 patients. The site of block was the His-Purkinje system in 4 of these 12 patients and the AV node in the remaining 8. At a cycle length with 1:1 VA conduction, a steady state VA conduction time was achieved in 2 to 4 beats (VA conduction time accommodation). The pattern of such accommodation depended on the site (His-Purkinje system versus AV node) of the maximal conduction delay. The steady state VA conduction time itself was altered with AV sequential pacing in patients showing His-Purkinje system delay, but not in patients with AV nodal delay. The results suggest that in most patients, the cycle length of VA block and the longest steady state VA conduction time will depend on the retrograde conduction time of the first beat of the tachycardia. In addition, pharmacologic measures to prevent or terminate endless loop tachycardia will have to take into account the fact that both the His-Purkinje system and the AV node can be the site of initial block.

Atrioventricular Node↗

PubMed2001

Plantar pressure and EMG activity of simulated and actual ski jumping take-off.

Plantar pressures and activation of the four muscles (VL - vastus lateralis, GL - gluteus, TA - tibialis anterior and GA - lat. gastrocnemius) were measured from ten ski jumpers under simulated laboratory conditions with training shoes (Lab TS) and with jumping boots (Lab JB) as well as in actual hill jumping conditions (Hill). The most significant differences between measured conditions were found in muscle activation patterns and plantar pressures prior to take-off. The centrifugal force due to the curvature of the inrun under actual hill jumping conditions caused extra pressure under the fore and rear parts of the feet (P<0.001) and therefore higher activation in all muscles (P<0.001 for VL, TA and GA and P<0.01 for GL). The actual take-off was characterized by high pressure under the toes during the early phase and high pressure under the heel during the latter phase of take-off. However, this should probably he interpreted as a commonly used improper technique where the balance during take-off is not well maintained to allow effective force production. Activation of GA, especially with regard to anteroposterior pressure distribution under the feet, differed significantly between the measured conditions. The role of GA for explosive force production during ski jumping take-off is much smaller as compared to that of the knee and hip extensor muscles.

Electromyography↗

PubMed1994

Visual field interpretation with a personal computer based neural network.

The Computer Assisted Touch Screen (CATS) and Computer Assisted Moving Eye Campimeter (CAMEC) are personal computer (PC)-based video-campimeters which employ multiple and single static stimuli on a cathode ray tube respectively. Clinical studies show that CATS and CAMEC provide comparable results to more expensive conventional visual field test devices. A neural network has been designed to classify visual field data from PC-based video-campimeters to facilitate diagnostic interpretation of visual field test results by non-experts. A three-layer back propagation network was designed, with 110 units in the input layer (each unit corresponding to a test point on the visual field test grid), a hidden layer of 40 processing units, and an output layer of 27 units (each one corresponding to a particular type of visual field pattern). The network was trained by a training set of 540 simulated visual field test result patterns, including normal, glaucomatous and neuro-ophthalmic defects, for up to 20,000 cycles. The classification accuracy of the network was initially measured with a previously unseen test set of 135 simulated fields and further tested with a genuine test result set of 100 neurological and 200 glaucomatous fields. A classification accuracy of 91-97% with simulated field results and 65-100% with genuine field results were achieved. This suggests that neural networks incorporated into PC-based video-campimeters may enable correct interpretation of results in non-specialist clinics or in the community.

Diagnosis, Computer-Assisted↗

PubMed2006

In vitro evaluation of forces exerted by a new computer-assisted colonoscope (the NeoGuide Endoscopy System).

BACKGROUND: The NeoGuide Endoscopy System (NES) utilizes a fully articulated, computer-controlled insertion tube that allows proximal segments of the colonoscope to follow the path taken by the tip as it is manually advanced through the colon. The system was designed to eliminate looping and scope displacement during colonoscopy. MATERIAL AND METHODS: Using in vitro testing, an inanimate flexible model of the colon incorporating four force transducers located at the key flexure points was employed to measure the axial forces on the colon wall during colonoscopy. In the second part of the study, 10 gastroenterologists performed colonoscopies, using a training latex-based simulator, with the NES and with a standard colonoscope. Colonic displacement was independently assessed by six gastroenterologists, with each evaluating endoscopist assigning a score between 0 and 5 corresponding to the maximum colonic displacement observed at any location. RESULTS: The average measured forces (in lbs) at three of the four flexure points were significantly lower ( P < 0.05) when the NES was used. The mean colonic displacement was significantly lower for procedures performed with the NES compared with the standard colonoscope (2.36 vs. 4.26, P < 0.001). Interobserver agreement regarding the degree of colonic displacement due to looping was moderate (weighted kappa = 0.45, P < 0.01). CONCLUSIONS: Colonoscopy with the NES was associated with significantly less looping and lateral force required for advancement than procedures with a standard colonoscope. The reduced amount of looping suggests that use of the NES in patients might be associated with less discomfort and thus require less sedation.

Biomechanical Phenomena↗

PubMedDate not supplied

Effects of intermittent hypoxic training on aerobic and anaerobic performance.

The aim of the present study was to determine whether short-term intermittent hypoxic training would enhance sea level aerobic and anaerobic performance over and above that occurring with equivalent sea level training. Over a 4-week period, two groups of eight moderately trained team sports players performed 30 min of cycling exercise three times per week. One group trained in normobaric hypoxia at a simulated altitude of 2750 m (F(I)O2= 0.15), the other group trained in a laboratory under sea level conditions. Each training session consisted of ten 1-min bouts at 80% maximum workload maintained for 2 min (Wmax) during the incremental exercise test at sea level separated by 2-min active recovery at 50% Wmax. Training intensities were increased by 5% after six training sessions and by a further 5% (of original Wmax) after nine sessions. Pre-training assessments of VO(2max), power output at onset of 4 mM blood lactate accumulation (OBLA), Wmax and Wingate anaerobic performance were performed on a cycle ergometer at sea level and repeated 4-7 d following the training intervention. Following training there were significant increases (p < 0.01) in VO(2max) (7.2 vs. 8.0%), Wmax (15.5 vs. 17.8%), OBLA (11.1 vs. 11.9%), mean power (8.0 vs. 6.5%) and peak power (2.9 vs. 9.3%) in both the hypoxic and normoxic groups respectively. There were no significant differences between the increases in any of the above-mentioned performance parameters in either training environment (p > 0.05). In addition, neither haemoglobin concentration nor haematocrit were significantly changed in either group (p > 0.05). It is concluded that acute exposure of moderately trained subjects to normobaric hypoxia during a short-term training programme consisting of moderate- to high-intensity intermittent exercise has no enhanced effect on the degree of improvement in either aerobic or anaerobic performance. These data suggest that if there are any advantages to training in hypoxia for sea level performance, they would not arise from the short-term protocol employed in the present study.

Adult↗