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Simulation technology: a comparison of experiential and visual learning for undergraduate medical students.

BACKGROUND: The availability of simulator technology at the University of Toronto (Toronto, Ontario, Canada) provided the opportunity to compare the efficacy of video-assisted and simulator-assisted learning. METHODS: After ethics approval from the University of Toronto, all final-year medical students were invited to participate in the current randomized trial comparing video-based to simulator-based education using three scenarios. After an introduction to the simulator environment, a 5-min performance-based pretest was administered in the simulator operating room requiring management of a critical event. A posttest was administered after students had participated in either a faculty-facilitated video or simulator teaching session. Standardized 12-point checklist performance protocols were used for assessment purposes. As well, students answered focused questions related to the educational sessions on a final examination. Student opinions regarding the value of the teaching sessions were obtained. RESULTS: One hundred forty-four medical students participated in the study (scenario 1, n = 43; scenario 2, n = 48; scenario 3, n = 53). There was a significant improvement in posttest scores over pretest scores in all scenarios. There was no statistically significant difference in scores between simulator or video teaching methods. There were no differences in final examination marks when the two educational methods were compared. Student opinions indicated that the experiential simulator sessions were more enjoyable and valuable than the video teaching sessions. CONCLUSIONS: Both simulator and video types of faculty-facilitated education offer a valuable learning experience. Future work is needed that addresses the long-term effects of experiential learning in the retention of knowledge and acquired skills.

Adult↗

Viewpoint: power and communication: why simulation training ought to be complemented by experiential and humanist learning.

The authors present an analysis of communication training for medical students using simulation patients, and its possible influence on later doctor-patient relationships. Many empirical studies have shown the various benefits of using simulation patients to teach communication skills, but theoretical sociology and humanistic reflection shed light on some fundamental differences between the student-doctor/actor-patient interactions practiced in simulation encounters and real doctor-patient relationships. In contrast to the usual power dynamics of a doctor-patient relation, those of simulation encounters are inverted and overwritten by an entirely different set of power relations, namely, those of the evaluator-student relationship. Since the power dynamics of real doctor-patient relations are generally overlooked, the altered dynamics of the simulation encounter are not readily perceived, and simulation encounters are thus often mistaken as accurate representations of clinical reality. Exclusive reliance on this pedagogic approach of simulation training may be encouraging students to become "simulation doctors" who act out a good relationship to their patients but have no authentic connection with them. The authors propose that liberal-arts learning and encounters with real patients should be used to cultivate students' abilities to create good doctor-patient relationships, as a compliment to the pedagogic benefits of simulation encounters.

Communication↗

Simulation training and resident performance of singleton vaginal breech delivery.

OBJECTIVE: To determine whether simulation training improves resident competency in the management of a simulated vaginal breech delivery. METHODS: Without advance notice or training, residents from 2 obstetrics and gynecology residency programs participated in a standardized simulation scenario of management of an imminent term vaginal breech delivery. The scenario used an obstetric birth simulator and human actors, with the encounters digitally recorded. Residents then received a training session with the simulator on the proper techniques for vaginal breech delivery. Two weeks later they were retested using a similar simulation scenario. A physician, blinded to training status, graded the residents' performance using a standardized evaluation sheet. Statistical analysis included the Wilcoxon signed rank test, McNemar chi2, regression analysis, and paired t test as appropriate with a P value of less than .05 considered significant. RESULTS: Twenty residents from 2 institutions completed all parts of the study protocol. Trained residents had significantly higher scores in 8 of 12 critical delivery components (P < .05). Overall performance of the delivery and safety in performing the delivery also improved significantly (P = .001 for both). CONCLUSION: Simulation training improved resident performance in the management of a simulated vaginal breech delivery. Performance of a term breech vaginal delivery is well suited for simulation training, because it is uncommon and inevitable, and improper technique may result in significant injury. LEVEL OF EVIDENCE: II-2.

Adult↗

Surgical simulation: a systematic review.

OBJECTIVE: To evaluate the effectiveness of surgical simulation compared with other methods of surgical training. SUMMARY BACKGROUND DATA: Surgical simulation (with or without computers) is attractive because it avoids the use of patients for skills practice and provides relevant technical training for trainees before they operate on humans. METHODS: Studies were identified through searches of MEDLINE, EMBASE, the Cochrane Library, and other databases until April 2005. Included studies must have been randomized controlled trials (RCTs) assessing any training technique using at least some elements of surgical simulation, which reported measures of surgical task performance. RESULTS: Thirty RCTs with 760 participants were able to be included, although the quality of the RCTs was often poor. Computer simulation generally showed better results than no training at all (and than physical trainer/model training in one RCT), but was not convincingly superior to standard training (such as surgical drills) or video simulation (particularly when assessed by operative performance). Video simulation did not show consistently better results than groups with no training at all, and there were not enough data to determine if video simulation was better than standard training or the use of models. Model simulation may have been better than standard training, and cadaver training may have been better than model training. CONCLUSIONS: While there may be compelling reasons to reduce reliance on patients, cadavers, and animals for surgical training, none of the methods of simulated training has yet been shown to be better than other forms of surgical training.

Computer Simulation↗

Cutting on triangle mesh: local model-based haptic display for dental preparation surgery simulation.

A new method to realize stable and realistic cutting simulation using an impedance display haptic device and microcomputer is presented in this paper. Material removal or cutting simulation is a critical task in dental preparation surgery simulation. In this paper, a piecewise contact force model is proposed to approximately describe the cutting process. Challenging issues of minimizing the difference between the cutting simulation and haptic contact simulation are analyzed. The proposed contact-based simulation method is developed for a one-dimensional cutting task and can be expanded to three-dimensional cases. Local model-based multirate simulation cutting architecture is proposed and force control of the haptic device is decoupled from the cutting simulation loop, which can both ensure high fidelity of dynamical simulation as well as maintain stability of the haptic device. The cutting operation is realized using spherical and cylindrical shaped tools. An experiment based on the Phantom desktop proves that fidelity in one-dimensional cutting can be realized and stability in three-dimensional cutting can be ensured using the force-filtering method.

Computer Simulation↗

Sensitivity to simulated directional sound motion in the rat primary auditory cortex.

Sensitivity to simulated directional sound motion in the rat primary auditory cortex. This paper examines neuron responses in rat primary auditory cortex (AI) during sound stimulation of the two ears designed to simulate sound motion in the horizontal plane. The simulated sound motion was synthesized from mathematical equations that generated dynamic changes in interaural phase, intensity, and Doppler shifts at the two ears. The simulated sounds were based on moving sources in the right frontal horizontal quadrant. Stimuli consisted of three circumferential segments between 0 and 30 degrees, 30 and 60 degrees, and 60 and 90 degrees and four radial segments at 0, 30, 60, and 90 degrees. The constant velocity portion of each segment was 0.84 m long. The circumferential segments and center of the radial segments were calculated to simulate a distance of 2 m from the head. Each segment had two trajectories that simulated motion in both directions, and each trajectory was presented at two velocities. Young adult rats were anesthetized, the left primary auditory cortex was exposed, and microelectrode recordings were obtained from sound responsive cells in AI. All testing took place at a tonal frequency that most closely approximated the best frequency of the unit at a level 20 dB above the tuning curve threshold. The results were presented on polar plots that emphasized the two directions of simulated motion for each segment rather than the location of sound in space. The trajectory exhibiting a "maximum motion response" could be identified from these plots. "Neuron discharge profiles" within these trajectories were used to demonstrate neuron activity for the two motion directions. Cells were identified that clearly responded to simulated uni- or multidirectional sound motion (39%), that were sensitive to sound location only (19%), or that were sound driven but insensitive to our location or sound motion stimuli (42%). The results demonstrated the capacity of neurons in rat auditory cortex to selectively process dynamic stimulus conditions representing simulated motion on the horizontal plane. Our data further show that some cells were responsive to location along the horizontal plane but not sensitive to motion. Cells sensitive to motion, however, also responded best to the moving sound at a particular location within the trajectory. It would seem that the mechanisms underlying sensitivity to sound location as well as direction of motion converge on the same cell.

Acoustic Stimulation↗

Anaesthetists' attitudes towards an anaesthesia simulator. A comparative survey: U.S.A. and Australia.

Anaesthesia simulation has been suggested as a method to enhance the training of clinicians without exposing patient to risk. Recently, two anaesthesia simulators have become commercially available in the U.S.A. Attitudes towards anaesthesia simulators have not been previously surveyed. With institutional approval, a survey questionnaire was given to 1. all clinical staff of the Department of Anesthesiology, University of Pittsburgh Medical Center, and 2. all anaesthetists attending the Annual General Meeting of the Australian Society of Anaesthetists. An information sheet containing details about anaesthesia simulation in general and the special capabilities of a particular commercial anaesthesia simulator was included with the survey instrument. The survey was anonymous and contained 15 questions. Attitudinal responses were recorded using an anchored visual analog 100 mm scale. We surveyed anaesthetists during September-October 1993. Completed forms were returned by 183 anaesthetists. Respondents were aged 25-67 years (mean age 41 +/- 10 yr) and were grouped by staff position (78% faculty, 22% trainees), sex (79% male; 21% female), country of practice (44% Aust, 56% U.S.A.) and years in practice. Seventy-three per cent staff were in favour (VAS > 60) of departmental purchase of a simulator (with no significant difference between countries) and 76% expressed willingness (VAS > 60) to undergo testing in their own time (with Australian anaesthetists significantly more willing to do so). However, 65% were not in favour (VAS < 40) of the compulsory use of a simulator for re-certification or re-accreditation of anaesthesia practitioners, with American anaesthetists (anesthesiologists) significantly more opposed to it. The most frequent comment related to the cost. There is majority support for the purchase of an anaesthesia simulator but there is widespread concern for its high cost. In general, anaesthesia simulation is perceived more as an education tool rather than an instrument for (re)certification.

Accreditation↗

Multiscale Hy3S: hybrid stochastic simulation for supercomputers.

BACKGROUND: Stochastic simulation has become a useful tool to both study natural biological systems and design new synthetic ones. By capturing the intrinsic molecular fluctuations of "small" systems, these simulations produce a more accurate picture of single cell dynamics, including interesting phenomena missed by deterministic methods, such as noise-induced oscillations and transitions between stable states. However, the computational cost of the original stochastic simulation algorithm can be high, motivating the use of hybrid stochastic methods. Hybrid stochastic methods partition the system into multiple subsets and describe each subset as a different representation, such as a jump Markov, Poisson, continuous Markov, or deterministic process. By applying valid approximations and self-consistently merging disparate descriptions, a method can be considerably faster, while retaining accuracy. In this paper, we describe Hy3S, a collection of multiscale simulation programs. RESULTS: Building on our previous work on developing novel hybrid stochastic algorithms, we have created the Hy3S software package to enable scientists and engineers to both study and design extremely large well-mixed biological systems with many thousands of reactions and chemical species. We have added adaptive stochastic numerical integrators to permit the robust simulation of dynamically stiff biological systems. In addition, Hy3S has many useful features, including embarrassingly parallelized simulations with MPI; special discrete events, such as transcriptional and translation elongation and cell division; mid-simulation perturbations in both the number of molecules of species and reaction kinetic parameters; combinatorial variation of both initial conditions and kinetic parameters to enable sensitivity analysis; use of NetCDF optimized binary format to quickly read and write large datasets; and a simple graphical user interface, written in Matlab, to help users create biological systems and analyze data. We demonstrate the accuracy and efficiency of Hy3S with examples, including a large-scale system benchmark and a complex bistable biochemical network with positive feedback. The software itself is open-sourced under the GPL license and is modular, allowing users to modify it for their own purposes. CONCLUSION: Hy3S is a powerful suite of simulation programs for simulating the stochastic dynamics of networks of biochemical reactions. Its first public version enables computational biologists to more efficiently investigate the dynamics of realistic biological systems.

Cell Physiological Phenomena↗

Molecular simulations of cotranslational protein folding: fragment stabilities, folding cooperativity, and trapping in the ribosome.

Although molecular simulation methods have yielded valuable insights into mechanistic aspects of protein refolding in vitro, they have up to now not been used to model the folding of proteins as they are actually synthesized by the ribosome. To address this issue, we report here simulation studies of three model proteins: chymotrypsin inhibitor 2 (CI2), barnase, and Semliki forest virus protein (SFVP), and directly compare their folding during ribosome-mediated synthesis with their refolding from random, denatured conformations. To calibrate the methodology, simulations are first compared with in vitro data on the folding stabilities of N-terminal fragments of CI2 and barnase; the simulations reproduce the fact that both the stability and thermal folding cooperativity increase as fragments increase in length. Coupled simulations of synthesis and folding for the same two proteins are then described, showing that both fold essentially post-translationally, with mechanisms effectively identical to those for refolding. In both cases, confinement of the nascent polypeptide chain within the ribosome tunnel does not appear to promote significant formation of native structure during synthesis; there are however clear indications that the formation of structure within the nascent chain is sensitive to location within the ribosome tunnel, being subject to both gain and loss as the chain lengthens. Interestingly, simulations in which CI2 is artificially stabilized show a pronounced tendency to become trapped within the tunnel in partially folded conformations: non-cooperative folding, therefore, appears in the simulations to exert a detrimental effect on the rate at which fully folded conformations are formed. Finally, simulations of the two-domain protease module of SFVP, which experimentally folds cotranslationally, indicate that for multi-domain proteins, ribosome-mediated folding may follow different pathways from those taken during refolding. Taken together, these studies provide a first step toward developing more realistic methods for simulating protein folding as it occurs in vivo.

Binding Sites↗

Computational simulations of interactions of scorpion toxins with the voltage-gated potassium ion channel.

Based on a homology model of the Kv1.3 potassium channel, the recognitions of the six scorpion toxins, viz. agitoxin2, charybdotoxin, kaliotoxin, margatoxin, noxiustoxin, and Pandinus toxin, to the human Kv1.3 potassium channel have been investigated by using an approach of the Brownian dynamics (BD) simulation integrating molecular dynamics (MD) simulation. Reasonable three-dimensional structures of the toxin-channel complexes have been obtained employing BD simulations and triplet contact analyses. All of the available structures of the six scorpion toxins in the Research Collaboratory for Structural Bioinformatics Protein Data Bank determined by NMR were considered during the simulation, which indicated that the conformations of the toxin significantly affect both the molecular recognition and binding energy between the two proteins. BD simulations predicted that all the six scorpion toxins in this study use their beta-sheets to bind to the extracellular entryway of the Kv1.3 channel, which is in line with the primary clues from the electrostatic interaction calculations and mutagenesis results. Additionally, the electrostatic interaction energies between the toxins and Kv1.3 channel correlate well with the binding affinities (-logK(d)s), R(2) = 0.603, suggesting that the electrostatic interaction is a dominant component for toxin-channel binding specificity. Most importantly, recognition residues and interaction contacts for the binding were identified. Lys-27 or Lys-28, residues Arg-24 or Arg-25 in the separate six toxins, and residues Tyr-400, Asp-402, His-404, Asp-386, and Gly-380 in each subunit of the Kv1.3 potassium channel, are the key residues for the toxin-channel recognitions. This is in agreement with the mutation results. MD simulations lasting 5 ns for the individual proteins and the toxin-channel complexes in a solvated lipid bilayer environment confirmed that the toxins are flexible and the channel is not flexible in the binding. The consistency between the results of the simulations and the experimental data indicated that our three-dimensional models of the toxin-channel complex are reasonable and can be used as a guide for future biological studies, such as the rational design of the blocking agents of the Kv1.3 channel and mutagenesis in both toxins and the Kv1.3 channel. Moreover, the simulation result demonstrates that the electrostatic interaction energies combined with the distribution frequencies from BD simulations might be used as criteria in ranking the binding configuration of a scorpion toxin to the Kv1.3 channel.

Amino Acid Sequence↗

Training in carotid artery stenting: do carotid simulation systems really help?

Virtual reality (VR) simulations have long been used for training in aviation and other professions. High-fidelity endovascular procedure simulators are now available, providing procedure simulations with real-time interactions; two-dimensional graphic displays of angiographic anatomy; mechanical interfaces with guidewires, sheaths, and catheters that provide some degree of haptic feedback; modeling of physiologic and pharmacology responses; and other features. Simulators have been incorporated into training programs for physicians learning carotid artery stenting (CAS). For the first time, US Food and Drug Administration approval of a new device (CAS systems) has included a requirement for physician training that incorporates the use of VR simulators. Early experience has shown that simulation is well accepted by trainees, performance on simulators improves with training and practice, and simulation prior to first performing endovascular procedures can improve clinical performance. Specific to CAS, the value of education programs using simulators appears to be tangible as trained but inexperienced CAS operators have clinical results comparable to those of physicians with extensive CAS experience.

Carotid Stenosis↗

Simulation of minimally invasive vascular interventions for training purposes.

OBJECTIVE: To master the skills required to perform minimally invasive vascular interventions, proper training is essential. A computer simulation environment has been developed to provide such training. The simulation is based on an algorithm specifically developed to simulate the motion of a guide wire--the main instrument used during these interventions--in the human vasculature. In this paper, the design and model of the computer simulation environment is described and first results obtained with phantom and patient data are presented. MATERIALS AND METHODS: To simulate minimally invasive vascular interventions, a discrete representation of a guide wire is used which allows modeling of guide wires with different physical properties. An algorithm for simulating the propagation of a guide wire within a vascular system, on the basis of the principle of minimization of energy, has been developed. Both longitudinal translation and rotation are incorporated as possibilities for manipulating the guide wire. The simulation is based on quasi-static mechanics. Two types of energy are introduced: internal energy related to the bending of the guide wire, and external energy resulting from the elastic deformation of the vessel wall. RESULTS: A series of experiments were performed on phantom and patient data. Simulation results are qualitatively compared with 3D rotational angiography data. CONCLUSIONS: The results indicate plausible behavior of the simulation.

Algorithms↗

Virtual reality flexible sigmoidoscopy simulator training: impact on resident performance.

BACKGROUND: Flexible sigmoidoscopy, a core skill for the primary care physician, requires learned hand-eye skills that can be difficult to master during residency training. With recent advances in virtual reality simulation technology, simulated flexible sigmoidoscopes are available to family medicine residents for training before their initial and subsequent live patient examinations. The purpose of the study was to determine whether a virtual reality flexible sigmoidoscope simulator would improve the hand-eye skills and various performance parameters in a live patient. METHODS: Residents were assigned to a control (n = 5) or experimental group (n = 5) in which the experimental group trained on a virtual reality sigmoidoscopy simulator before their first sigmoidoscopies on live patient volunteers. After the initial live patient sigmoidoscopies, both control and experimental groups trained on the simulator so that it was possible to evaluate presimulator and postsimulator training effects on live patient performance and to compare speed and skill between the groups at different levels of training. RESULTS: Training on the virtual reality simulator produced substantial improvements in examination times and hand-eye skill measures. After 6 to 10 hours of training on the simulator, the experimental group achieved significantly faster insertion times to 30 cm (119 versus 357 sec, P = 0.03), 40 cm (211 versus 518 sec, P = 0.03), and a shorter mean length of examination (323 versus 654 sec, P = 0.01). There was also significant improvement of hand-eye skill measures of the experimental group in directional errors (1.6 versus. 8.6, P < 0.01), percentage of colon visualized (79 versus 45 percent, P = 0.02), and viewing quality of examination when compared with the control group's initial performance on live patients. Resident survey findings after the study confirmed the trainee's perception of the benefit of the simulator training. CONCLUSIONS: This study shows the value of virtual reality simulator training for accelerating the development of the hand-eye skills to perform adequate sigmoidoscopy.

Clinical Competence↗

Programming of a flexible computer simulation to visualize pharmacokinetic-pharmacodynamic models.

Teaching pharmacokinetic-pharmacodynamic (PK/PD) models can be made more effective using computer simulations. We propose the programming of educational PK or PK/PD computer simulations as an alternative to the use of pre-built simulation software. This approach has the advantage of adaptability to non-standard or complicated PK or PK/PD models. Simplicity of the programming procedure was achieved by selecting the LabVIEW programming environment. An intuitive user interface to visualize the time courses of drug concentrations or effects can be obtained with pre-built elements. The environment uses a wiring analogy that resembles electrical circuit diagrams rather than abstract programming code. The goal of high interactivity of the simulation was attained by allowing the program to run in continuously repeating loops. This makes the program behave flexibly to the user input. The programming is described with the aid of a 2-compartment PK simulation. Examples of more sophisticated simulation programs are also given where the PK/PD simulation shows drug input, concentrations in plasma, and at effect site and the effects themselves as a function of time. A multi-compartmental model of morphine, including metabolite kinetics and effects is also included. The programs are available for download from the World Wide Web at http:// www. klinik.uni-frankfurt.de/zpharm/klin/ PKPDsimulation/content.html. For pharmacokineticists who only program occasionally, there is the possibility of building the computer simulation, together with the flexible interactive simulation algorithm for clinical pharmacological teaching in the field of PK/PD models.

Algorithms↗

Visual neglect: occurrence and patterns in pilots in a simulated overnight flight.

INTRODUCTION: Visual neglect is the unconscious inability to recognize or acknowledge some visual information in the presence of a structurally intact visual system, and was hypothesized to occur with less than 24 h of continuous wakefulness. Visual perception was evaluated in military pilots during a simulated overnight flight to explore for the possible occurrence of visual neglect. METHODS: There were eight military pilots (male, 31-52 yr of age, mean 37 yr) on flight status who were recruited to perform the primary task of flying a simulated 12.5 h overnight mission after a day of continuous wakefulness and the secondary task of responding to repeated 20 min presentations of single- and double-light stimuli displayed in random sequence at 15 degrees intervals across the cockpit instrument panel. In addition to the visual performance task, simulator shutdowns occurring when the tolerances of the simulator were exceeded were measured and simple reaction time on the psychomotor vigilance task was assessed. Total continuous wakefulness was 26.5 h. RESULTS: Combined performance on the visual perception task showed response omissions increasing at 19 h of continuous wakefulness. Patterns included omissions at all stimulus locations, of primarily peripherally located stimuli, and of one of two simultaneously presented stimuli. Simulator shutdowns began at 21.5 h of continuous wakefulness. Correlation of visual task response omissions with simulator shutdowns was r = 0.95, p < 0.0001. CONCLUSIONS: Significant neglect of visual stimuli occurred in pilots beginning at 19 h of continuous wakefulness in a simulated overnight fixed wing aircraft flight, preceded simulator shutdowns, and correlated at 0.95 with simulator shutdowns.

Aircraft↗

Transatlantic medical education: preliminary data on distance-based high-fidelity human patient simulation training.

Advanced training using Human Patient Simulators (HPS) is, for the large part, unavailable for the majority of healthcare providers in rural, remote, and less developed regions of the world--either due to their separation from the major medical education centers or significant fiscal austerity. Remote access to HPS based on the Applications Software Provider principles may provide the solution to this problem. The medical ASP (MED-ASP) concept proposed and developed by MedSMART has been subjected to an extensive qualitative and quantitative international test conducted among France, Italy, and USA. Two SimMan HPSs (Laerdal, Norway) were used, with one unit based in Ann Arbor, MI, USA, and one in Laval, France. While the French site had both remote and hands-on access to the simulator, the Italian site could access the HPS only remotely. Simulator visualization was provided by 4 remotely operated cameras (Sony, zoom, pan, tilt) at each HPS site. HPS-generated vital signs were transmitted to each site together with the interactive simulator control panel using a communications hub at the MedSMART facility in Ann Arbor. All remote interactions were performed via the Internet (TCP/IP) using ISDN and/or ADSL connections at minimum 128 Kbps. During the course of training, the trainees were exposed to 3 emergency scenarios with the remote expert providing instruction. Interventions were performed either remotely (Italy) or remotely and hands-on (France). Quantitative measurement of the efficiency of training was performed at the Italian site based on the evaluation of video recordings of each session and the assessment of several performance measures. At the end of the training program, a Likert scale-based assessment test was also given. The trainees showed statistically significant (p<0.03 - 0.05) improvement in all testing measures. The Likert scale questionnaire revealed overwhelming satisfaction with the simulation-based distance training even when the access to the simulator was only remote (Italy). Confidence was also significantly improved. The trainees indicated the optimal frequency of distance training as one 2 hour-long session twice a month. In conclusion, simulation-based distance medical training proved to be a highly effective tool in improving emergency medical skills of junior physician trainees and, despite initial reservations, neither distance nor language and cultural differences posed significant obstacles. The present and historical data from our previous work confirm the concept of MED-ASP as a highly efficient tool in both national and international medical education and training. Moreover, we now validate for the first time the concept of simulation-based, fully interactive transatlantic medical ADL that we have proposed in our previous theoretical papers. The present experiments prove that training based on advanced technologies transcends barriers of distance, time, and national medical guidelines. Hence, international simulation-based distance training may ultimately provide the most realistic platform for a large-scale training of emergency medical personnel in less developed countries and in rural/remote regions of the globe.

Education, Distance↗

[Effects of high +Gx during simulated spaceship emergency return on learning and memory in rats].

OBJECTIVE: To observe the effects of high +Gx during simulated spaceship emergency return on learning and memory in rats. METHOD: Thirty two male SD rats were randomly divided into control group, 7 d simulated weightlessness group, +15 Gx/180 s group and +15 Gx/180 s exposure after 7 d simulated weightlessness group, with 8 rats in each group. The changes of learning and memory in rats were measured after stresses by means of Y-maze test and step-through test. RESULT: In Y-maze test, as compared with control group, percentage of correct reactions decreased significantly (P<0.01) and reaction time increased significantly (P<0.01) in hypergravity after simulated weightlessness group at all time after stress; as compared with +15 Gx group or simulated weightlessness group, percentage of correct reactions decreased significantly (P< 0.05) and reaction time increased significantly (P< 0.05) immediately after stress. In step-through test, as compared with control group, total time increased significantly (P<0.01) in hypergravity after simulated weightlessness group at 1 d after stress; latent time decreased significantly (P<0.01) and number of errors increased significantly (P< 0.01) at all the time after stress. As compared with +15 Gx group, total time increased significantly (P<0.05) immediately, 1 d after stress. As compared with simulated weightlessness group, total time and number of errors increased significantly (P<0.05) immediately after stress. CONCLUSION: It is suggested that +15 Gx/180 s and simulated weightlessness may affect the ability of learning and memory of rats. Simulated weightlessness for 7 d can aggravate the effect of +Gx on learning and memory ability in rats.

Animals↗

[Study on the simulation in planning for orthognathic surgery by using a personal computer].

This study was made in order to develop and evaluate three-dimensional simulation programs in planning for orthognathic surgery by using microcomputer system. Microcomputer system is composed of CPU (NEC, PC-9801), high resolutional color display, color printer, image scanner, and MOUSE. This simulation is composed of four procedures. 1. Data input Three-dimensional coordinate data on tracing obtained from CT films is inputted. One data file is made from one outline of structures. 2. Three dimensional reconstruction A control file is made to arrange data files constructing structures. 3. Simulation This procedure is composed of cutting and movement. The horizontal projection of mandible is displayed. After cutting simulated orthognathic surgery is designed, new data files and new control file are made. A movement consists of parallel translation and rotation. A movement data is combined with movements designed on each of three projections. 4. Three-dimensional graphic display Three-dimensional graphics of the mandible before and after a simulation for orthognathic surgery are displayed by perspective views with treated hidden lines and accurate pictures (COSMOZONE 2SA, NIKON). These simulation programs were carried out with the asymmetrical patient. The simulation was supposed that the operation was combined with sagittal splitting osteotomy of the right mandibular ramus and body ostectomy of the left lower first premolar part. Three-dimensional graphics of the mandible before and after the simulation were presented. Its three-dimensional mandibular position and form after orthognathic surgery were predicted. These three-dimensional simulation programs may be important procedure, when a treatment planning in asymmetrical prognathic case is discussed.

Computer Graphics↗