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Results for “Simulation Training”

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At least 1,027 records · Page 57Linked to original sources

PubMed2000

Pitch matches between unresolved complex tones differing by a single interpulse interval.

The experiment compared the pitches of complex tones consisting of unresolved harmonics. The fundamental frequency (F0) of the tones was 250 Hz and the harmonics were bandpass filtered between 5500 and 7500 Hz. Two 20-ms complex-tone bursts were presented, separated by a brief gap. The gap was an integer number of periods of the waveform: 0, 4, or 8 ms. The envelope phase of the second tone burst was shifted, such that the interpulse interval (IPI) across the gap was reduced or increased by 0.25 or 0.75 periods (1 or 3 ms). A "no shift" control was also included, where the IPI was held at an integer number of periods. Pitch matches were obtained by varying the F0 of a comparison tone with the same temporal parameters as the standard but without the shift. Relative to the no-shift control, the variations in IPI produced substantial pitch shifts when there was no gap between the bursts, but little effect was seen for gaps of 4 or 8 ms. However, for some conditions with the same IPI in the shifted interval, an increase in the IPI of the comparison interval from 4 to 8 ms (gap increased from 0 to 4 ms) changed the pitch match. The presence of a pitch shift suggests that the pitch mechanism is integrating information across the two tone bursts. It is argued that the results are consistent with a pitch mechanism employing a long integration time for continuous stimuli that is reset in response to temporal discontinuities. For a 250-Hz F0, an 8-ms IPI may be sufficient for resetting. Pitch models based on a spectral analysis of the simulated neural spike train, on an autocorrelation of the spike train, and on the mean rate of pitch pulses, all failed to account for the observed pitch matches.

Adult↗

PubMed2005

Crises in clinical care: an approach to management.

A "crisis" in health care is "the point in the course of a disease at which a decisive change occurs, leading either to recovery or to death". The daunting challenges faced by clinicians when confronted with a crisis are illustrated by a tragic case in which a teenage boy died after a minor surgical procedure. Crises are challenging for reasons which include: presentation with non-specific signs or symptoms, interaction of complex factors, progressive evolution, new situations, "revenge effects", inadequate assistance, and time constraints. In crises, clinicians often experience anxiety- and overload-induced performance degradation, tend to use "frequency gambling", run out of "rules" and have to work from first principles, and are prone to "confirmation bias". The effective management of crises requires formal training, usually simulator-based, and ideally in the inter-professional groups who will need to function as a team. "COVER ABCD-A SWIFT CHECK" is a pre-compiled algorithm which can be applied quickly and effectively to facilitate a systematic and effective response to the wide range of potentially lethal problems which may occur suddenly in anaesthesia. A set of 25 articles describing additional pre-compiled responses collated into a manual for the management of any crisis under anaesthesia has been published electronically as companion papers to this article. This approach to crisis management should be applied to other areas of clinical medicine as well as anaesthesia.

Algorithms↗

PubMed2006

Self-wiring in neural nets of point-like cortical neurons fails to reproduce cytoarchitectural differences.

We propose a model for description of activity-dependent evolution and self-wiring between binary neurons. Specifically, this model can be used for investigation of growth of neuronal connectivity in the developing neocortex. By using computational simulations with appropriate training pattern sequences, we show that long-term memory can be encoded in neuronal connectivity and that the external stimulations form part of the functioning neocortical circuit. It is proposed that such binary neuron representations of point-like cortical neurons fail to reproduce cytoarchitectural differences of the neocortical organization, which has implications for inadequacies of compartmental models.

Action Potentials↗

PubMed2001

Impact of pulsatility on the ensemble orderliness (approximate entropy) of neurohormone secretion.

Regular patterns of neurohormone secretion are driven by underlying pulsatile and subordinate (feedback sensitive) dynamics. Measures of time-series orderliness, e.g., the approximate entropy (ApEn) statistic (Pincus SM. Proc Natl Acad Sci 88: 2297-2301, 1991), vividly discriminate pathological and physiological patterns of hormone release. To investigate how specific pulsatility features impact regularity estimates, we have examined the sensitivity of the ApEn metric to systematic variations in the frequency, amplitude, and half-life of simulated neurohormone pulse trains (Veldhuis JD, Carlson ML, and Johnson ML. Proc Natl Acad Sci 84: 7686-7690, 1987) and compared the impact of a high vs. low baseline luteinizing hormone (LH) pattern regularity state mimicking the normal female luteal phase and the young male, respectively. Shortening the interpulse interval length elevated ApEn in both pulsatility models, thereby signifying greater ensemble series irregularity. The frequency sensitivity of ApEn was robust to several complementary renditions of ApEn and to variations in experimental uncertainty, basal (nonpulsatile) LH secretion, and secretory burst amplitude. ApEn rose with increasing hormone half-life, especially in the face of low baseline variability emulated by midluteal LH secretion profiles. High variability of secretory burst amplitude, pulse duration, or interpeak intervals increased ApEn in the more orderly femalelike construct; in the highly irregular malelike LH pulse model, these variability changes had little effect on ApEn. In summary, the ensemble regularity statistic, ApEn, quantifies unequal pattern orderliness in neurohormone pulse trains with minimal dependence on mean pulse amplitude, interpulse baseline, or (subthreshold) sample uncertainty. Thus ApEn monitors changing secretory event frequency and interpulse variability with sensitivity to starting pattern regularity, providing a mechanistic linkage between model evolution and statistical change.

Female↗

PubMed2001

Assessment of respiratory system mechanics by artificial neural networks: an exploratory study.

We evaluated 1) the performance of an artificial neural network (ANN)-based technology in assessing the respiratory system resistance (Rrs) and compliance (Crs) in a porcine model of acute lung injury and 2) the possibility of using, for ANN training, signals coming from an electrical analog (EA) of the lung. Two differently experienced ANNs were compared. One ANN (ANN(BIO)) was trained on tracings recorded at different time points after the administration of oleic acid in 10 anesthetized and paralyzed pigs during constant-flow mechanical ventilation. A second ANN (ANN(MOD)) was trained on EA simulations. Both ANNs were evaluated prospectively on data coming from four different pigs. Linear regression between ANN output and manually computed mechanics showed a regression coefficient (R) of 0.98 for both ANNs in assessing Crs. On Rrs, ANN(BIO) showed a performance expressed by R = 0.40 and ANN(MOD) by R = 0.61. These results suggest that ANNs can learn to assess the respiratory system mechanics during mechanical ventilation but that the assessment of resistance and compliance by ANNs may require different approaches.

Animals↗

PubMed1992

Respiratory-related neural assemblies in the brain stem midline.

1. The initial objective of this study was to determine whether respiratory-related neural assemblies exist in the brain stem midline. A second goal was to seek evidence for concurrent relationships among the neurons that could generate the detected synchrony. 2. Experiments were conducted on anesthetized, paralyzed, bilaterally vagotomized, artificially ventilated cats. Spike trains of four to nine simultaneously monitored neurons were recorded in the regions of n. raphe obscurus-n. raphe pallidus and n. raphe magnus. 3. Data were analyzed with cycle-triggered histograms, cross-correlograms, snowflakes, and the gravitational representation. A significance test for the gravity method was developed and tested with spike trains generated by simulated networks with defined connections. 4. Ninety-three groups of neurons from 24 cats were studied. Thirty-nine groups from 19 cats included neurons that discharged synchronously on a millisecond time scale; less than or equal to 19 pairs of synchronously discharging neurons were found in one group. Twenty-seven of these 39 groups included neurons that had respiratory-modulated firing rates and discharged synchronously with other group members. Synchronous assemblies included cells monitored at rostral or caudal locations, or both. 5. Six classes of relationships were inferred from groups of neurons with multiple correlations: divergence (n = 11); convergence (n = 7); connections with opposite actions between neurons (n = 5); projections of synchronous neurons to separate targets (n = 5); projections to one neuron in a synchronous group (n = 4); and projections between two synchronous groups with common elements (n = 6). 6. The results document the existence of assemblies of synchronously discharging respiratory-related neurons in midline regions of the brain stem and suggest that divergent excitatory and inhibitory connections within the midline participate in the generation of that synchrony. Links between assemblies may operate to stabilize their collective activity in a particular state.

Afferent Pathways↗

PubMed2006

Novices in surgery are the target group of a virtual reality training laboratory.

BACKGROUND: This study aims to establish which physicians represent the suitable target group of a virtual training laboratory. METHODS: Novices (48 physicians with fewer than 10 laparoscopic operations) and intermediate trainees (19 physicians who performed 30-50 laparoscopic operations) participated in this study. Each participant performed the basic module 'clip application' at the beginning and after a 1-hour short training course on the LapSim. The course consisted of the tasks coordination, lift and grasp, clip application, cutting with diathermy and fine dissection at increasing difficulty levels. The time taken to complete the tasks, number of errors, and economy of motion parameters (path length and angular path) were analyzed. RESULTS: Following training with the simulator, novices completed the task significantly faster (p = 0.001), demonstrated a greater economy of motion [path length (p = 0.04) and angular path (p = 0.01)]. In contrast, the intermediate trainees showed a reduction of their errors, but without reaching statistical significance. They showed no improvement in economy of motion and completed the task significantly slower (p = 0.03). CONCLUSION: Novices, in comparison to intermediate trainees, tend to benefit most during their first exposure to a laparoscopy simulator.

Adult↗

PubMed2002

Unitary events in multiple single-neuron spiking activity: I. Detection and significance.

It has been proposed that cortical neurons organize dynamically into functional groups (cell assemblies) by the temporal structure of their joint spiking activity. Here, we describe a novel method to detect conspicuous patterns of coincident joint spike activity among simultaneously recorded single neurons. The statistical significance of these unitary events of coincident joint spike activity is evaluated by the joint-surprise. The method is tested and calibrated on the basis of simulated, stationary spike trains of independently firing neurons, into which coincident joint spike events were inserted under controlled conditions. The sensitivity and specificity of the method are investigated for their dependence on physiological parameters (firing rate, coincidence precision, coincidence pattern complexity) and temporal resolution of the analysis. In the companion article in this issue, we describe an extension of the method, designed to deal with nonstationary firing rates.

Action Potentials↗

PubMed2003

Visual development and the acquisition of motion velocity sensitivities.

We consider the hypothesis that systems learning aspects of visual perception may benefit from the use of suitably designed developmental progressions during training. Four models were trained to estimate motion velocities in sequences of visual images. Three of the models were developmental models in the sense that the nature of their visual input changed during the course of training. These models received a relatively impoverished visual input early in training, and the quality of this input improved as training progressed. One model used a coarse-to-multiscale developmental progression (it received coarse-scale motion features early in training and finer-scale features were added to its input as training progressed), another model used a fine-to-multiscale progression, and the third model used a random progression. The final model was nondevelopmental in the sense that the nature of its input remained the same throughout the training period. The simulation results show that the coarse-to-multiscale model performed best. Hypotheses are offered to account for this model's superior performance, and simulation results evaluating these hypotheses are reported. We conclude that suitably designed developmental sequences can be useful to systems learning to estimate motion velocities. The idea that visual development can aid visual learning is a viable hypothesis in need of further study.

Artifacts↗

PubMed2005

Theory of the snowflake plot and its relations to higher-order analysis methods.

The snowflake plot is a scatter plot that displays relative timings of three neurons. It has had rather limited use since its introduction by Perkel, Gerstein, Smith, and Tatton (1975), in part because its triangular coordinates are unfamiliar and its theoretical properties are not well studied. In this letter, we study certain quantitative properties of this plot: we use projections to relate the snowflake plot to the cross-correlation histogram and the spike-triggered joint histogram, study the sampling properties of the plot for the null case of independent spike trains, study a simulation of a coincidence detector, and describe the extension of this plot to more than three neurons.

Computer Simulation↗

PubMed1986

The acute effects of exercise on prolactin and growth hormone secretion: comparison between sedentary women and women runners with normal and abnormal menstrual cycles.

Acute exercise may stimulate PRL secretion, which, in turn, may contribute to exercise-associated menstrual dysfunction. We compared the response of PRL secretion in sedentary women and women runners with normal and abnormal menstrual cycles. We also studied the GH response to acute exercise, as GH may bind to lactogenic receptors. Five nonrunning women, 5 eumenorrheic running women, four oligomenorrheic running women, and six amenorrheic running women were studied on 2 consecutive days. On day 1, the women cycled on a bicycle ergometer against an increasing workload until total exhaustion. Serum PRL and GH increased several-fold in response to acute exercise in all three groups of running women. On day 2, the women simulated a daily training run by enduring a designed submaximal exercise regimen. In response to submaximal exercise, no group had a significant elevation of PRL or GH. Therefore, a threshold of exercise intensity exists that must be achieved before a significant increase in PRL or GH secretion occurs in women runners; serum PRL and GH in the nonrunning group did not increase significantly even in response to acute maximal exercise. The transient elevations in PRL and GH in women runners probably do not contribute to their menstrual dysfunction unless individual hypersensitivity of the hypothalamic-pituitary-ovarian axis to such intermittent elevations is present.

Adult↗

PubMed2004

Limitations of ordinary least squares models in analyzing repeated measures data.

PURPOSE: To a) introduce and present the advantages of linear mixed models using generalized least squares (GLS) when analyzing repeated measures data; and b) show how model misspecification and an inappropriate analysis using repeated measures ANOVA with ordinary least squares (OLS) methodology can negatively impact the probability of occurrence of Type I error. METHODS: The effects of three strength-training groups were simulated. Strength gains had two slope conditions: null (no gain), and moderate (moderate gain). Ten subjects were hypothetically measured at five time points, and the correlation between measurements within a subject was modeled as compound symmetric (CS), autoregressive lag 1 (AR(1)), and random coefficients (RC). A thousand data sets were generated for each correlation structure. Then, each was analyzed four times--once using OLS, and three times using GLS, assuming the following variance/covariance structures: CS, AR(1), and RC. RESULTS: OLS produced substantially inflated probabilities of Type I errors when the variance/covariance structure of the data set was not CS. The RC model was less affected by the actual variance/covariance structure of the data set, and gave good estimates across all conditions. CONCLUSIONS: Using OLS to analyze repeated measures data is inappropriate when the covariance structure is not known to be CS. Random coefficients growth curve models may be useful when the variance/covariance structure of the data set is unknown.

Endpoint Determination↗

PubMedDate not supplied

Constructing a World Wide Web site for disaster management and humanitarian assistance.

There is a huge need for access to information in the areas of disaster relief, disaster medicine, and humanitarian assistance. The extraordinarily rapid increase in the literature in these subject areas attests to this need. However, use of the printed word has substantial limitations that are even more profound in the developing world. Currently, the information available tends to be fragmented and sequestered by the specific interests of the organizations and governments involved. The evolving electronic methods for the storage, organization, and retrieval of information makes coordination between organizations concerned with disasters within our grasp. This paper discusses the Center of Excellence in Disaster Management and Humanitarian Assistance and describes the World Wide Web and the implications it has in disaster management and medicine. It describes methods for obtaining user input to the techniques used for the development of the world wide web for the areas of disaster management and disaster medicine. The implementation of an on-line Internet reference desk that will provide: 1) a list of "experts;" 2) a searchable disaster database; and 3) on-line simulation courses and training exercises also is discussed.

Disasters↗

PubMed1999

[Evaluation of the ambulatory blood pressure monitor SAVE 33 model 2].

UNLABELLED: This work tests a new ambulatory blood pressure device: Save 33 II. The evaluation is conducted according to the phases II and IV of the British Hypertension Society (BHS) protocol: the phases I and III (before and after use) are not performed as this device has received the European quality label 'CE' that guarantees a +/- 3 mmHg accuracy before and after 10,000 simulated cycles. Two trained observers (hearing test and certification done according to the BHS recommendations) have performed 7 sequential BP measurements with conventional and automatic method, at the same arm, among 85 patients. The ranges of mean blood pressure are 78-203 mmHg, for SBP and 53-130 mmHg for DBP. RESULTS: The Save 33 II monitor satisfies the grade B of BHS evaluation for both systolic and diastolic pressures. This device also satisfies the Association for the Advancement of Medical Instrumentation (AAMI) protocol: mean difference between methods and standard deviation less than 5 +/- 8 mmHg: -2.7 +/- 6.8 mmHg for SBP and -0.86 +/- 6.6 mmHg for DBP. The in-use assessment is conform to BHS criteria for 20 recordings (less than 20% invalid values during day and night); the 5 other recordings have not enough night values, due to batteries failure (2 cases), sleeping discomfort (2 cases) and a cuff withdraw. CONCLUSION: This device, in the tested configuration, agrees the B grade of BHS and can be recommended for ambulatory blood pressure measurement.

Adolescent↗

PubMed1998

[Analysis of human posture control under weightlessness].

Dynamic equations of human trunk and limbs in weightlessness were established, and the motions in 6 dimensions were resolved into 3 motions in 3 dimensions. The feasibility and operability of human posture control in weightlessness by using simple actions were described directly with analysis, calculation and dynamic simulation, and the training methods on the Earth were proposed.

Aerospace Medicine↗

PubMed2005

[Role of anesthesiologists is the education of cardiopulmonary resuscitation in local hospitals].

BACKGROUND: In Japanese local hospitals there are not many persons who can give speedy and exact medical treatment in emergency. We investigated a role of anesthesiologists in the education of cardiopulmonary resuscitation (CPR) in local hospitals. METHODS: A total of 3 doctors and 30 nurses completed the questionnaire about the education of CPR after training of advanced cardiac life support (ACLS) in a local hospital. RESULTS: It showed that all doctors and nurses have had some anxiety about the emergency treatment of patients and could understand the importance of CPR. Moreover, most of them answered that they wanted to learn ACLS more, and that the training of ACLS simulation was the most impressive. CONCLUSIONS: It is important for anesthesiologists to teach ACLS and to promote the spread of ACLS in local hospitals.

Anesthesiology↗

PubMed1990

[Education (university training in mechanical sutures)].

The advances in surgical sciences and their evolution, besides the increasing number of surgical residents and the low availability of the operating-rooms, have made clear the limits of the usual teaching methods and of the integrative theoretical learning instruments. The teaching of viscero-synthesis, particularly mechanical suture training, emphasizes such problems and encourages the development of additional training programmes, including simulation, before the admittance to operative procedures.

Education, Medical, Graduate↗

PubMed1995

Novel methods for endoscopic training.

The development of past, present, and future endoscopic training methods is described. A historical perspective of endoscopy training guidelines and devices is used to demonstrate support for the use of novel endoscopic training techniques. Computer simulation of endoscopy, interactive learning, and virtual reality applications in endoscopy and surgery are reviewed. The goals of endoscopic simulation and challenges facing investigators in this field are discussed, with an emphasis on current and future research.

Computer Simulation↗