Computers and biomedical research, an international journal
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Comput. Biomed. Res. · Feb 2000
Augmented reality simulator for training in two-dimensional echocardiography.
In two-dimensional echocardiography the sonographer must synthesize multiple tomographic slices into a mental three-dimensional (3D) model of the heart. Computer graphics and virtual reality environments are ideal to visualize complex 3D spatial relationships. In augmented reality (AR) applications, real and virtual image data are linked, to increase the information content. ⋯ Modifications of the cutting plane within the echocardiographic data are transferred and visualized simultaneously and in real time within the reference scenario. The trainee can interactively explore the 3D heart model and the registered 3D echocardiographic data sets by an animated ultrasound probe, whose position is controlled by an electromagnetic tracking system. The tracking system is attached to a dummy transducer and placed on a plastic puppet to give a realistic impression of a two-dimensional echocardiographic examination.
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Comput. Biomed. Res. · Jun 1999
Comparative StudySelf-learning fuzzy control with temporal knowledge for atracurium-induced neuromuscular block during surgery.
Self-learning fuzzy logic control has the important property of accommodating uncertain, nonlinear, and time-varying process characteristics. This intelligent control scheme starts with no fuzzy control rules and learns how to control each process presented to it in real time without the need for detailed process modeling. In this study we utilize temporal knowledge of generated rules to improve control performance. ⋯ We developed a computer control system utilizing Relaxograph (Datex) measurements to assess the clinical performance of a self-learning fuzzy controller in this application. Using a T1 setpoint of 10% of baseline in 10 patients undergoing general surgery, we found a mean T1 error of 0.28% (SD = 0.39%) while accommodating a 0.25 to 0.38 mg/kg/h range in the mean atracurium infusion rate. This result compares favorably with more complex and computationally intensive model-based control strategies for atracurium infusion.
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Comput. Biomed. Res. · Apr 1999
Comparative StudyAn algebraic solution to dead space determination according to Fowler's graphical method.
According to Fowler's method, anatomical dead space (VD) can be determined graphically or computer-aided by iteration procedures by which phase III of a fraction-volume expirogram F(V) is back-extrapolated by a straight line R(V). Whereas Fowler visually partitioned phase II into two equal areas bordered by F(V), R(V), and VD, in the present paper the area between F(V) and R(V) is set equal to the area of a trapezoid, one side of which is the unknown VD to be determined. ⋯ The derived equations were tested in experimental situations, showing equality between values of dead space determined by using the algebraic solution and the graphical method. Their major advantage is facilitating and speeding up computer-aided on-line determinations of VD.
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Comput. Biomed. Res. · Oct 1998
Multigrid solution of the potential field in modeling electrical nerve stimulation.
In this paper, multilevel techniques are introduced as a fast numerical method to compute 3-D potential field in nerve stimulation configurations. It is shown that with these techniques the computing time is reduced significantly compared to conventional methods. ⋯ Subsequently, some essential elements for successful application are discussed. Finally, results are presented for the potential field in a nerve bundle induced by tripolar stimulation with a cuff electrode surrounding part of the nerve.
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Comput. Biomed. Res. · Aug 1998
Enhancing the power of record linkage involving low quality personal identifiers: use of the best link principle and cause of death prior likelihoods.
The Heartstart Scotland study collects details of all resuscitation attempts carried out by the Scottish Ambulance Service. The linkage between records for Heartstart study subjects who died before admission to a hospital and the national file of death records maintained by the Registrar General for Scotland is described. ⋯ In addition, although no cause of death information was recorded on the Heartstart records, a priori expectations of the distribution of causes of death among linked death records were used. Despite these enhancements, however, clerical resolution of a proportion of the potential links generated by the automatic algorithm significantly improved the accuracy of the linkage.