The effects of accumulated experience on radiofrequency ablation of accessory pathways

Increasing experience in radiofrequency ablation for accessory pathways appears to reduce the procedure time, radiation time and radiofrequency pulse number, and results in a higher success rate. However, the effect of a learning curve on this procedure from the perspective of location and conduction direction of accessory pathways has not been reported before. The purpose of this study was to determine the effect of accumulated experience on the outcomes of radiofrequency ablation for accessory pathways and on the duration of the procedure parameters by analyzing the results of a dedicated ablation team. The first 512 patients with a single accessory pathway treated in this laboratory were included for analysis of the procedure parameters with respect to locations and conduction directions of accessory pathways. The results showed that the average procedure time, radiation time, and radiofrequency pulse number differed significantly among the different subgroups (left free wall, right free wall, posteroseptal and anteromidseptal location; manifest or concealed conduction). All subgroups except the anteromidseptal pathways showed a significant improvement of the procedure parameters with increased ablation experience. Although the initial rate of improvement was similar among the different subgroups, the rate of improvement in left free wall pathways nearly reached a plateau after 120 ablation procedures. Thus it was concluded that a certain number of ablation procedures was necessary before achievement of a high success rate with shorter procedure and radiation times and a lower radiofrequency pulse number.     

Shrinkage estimation of scale parameter of the extreme-valuedistribution

The author studies the usual preliminary test estimator of the scale parameter of the extreme-value distribution in censored samples. The optimum levels of significance and their corresponding critical values for the preliminary test are obtained based on the minimax regret criterion. A preliminary test shrinkage estimator that is smoother than the usual preliminary test estimator is proposed as well. The optimum values of shrinkage coefficients for the preliminary test shrinkage estimator are obtained, and are also based on the minimax regret criterion. Comparison of these two estimators shows that if the mean square error is a criterion of goodness of estimation then the preliminary test shrinkage estimator is better than the usual preliminary test estimator     

Investigating the shape memory properties of 4D printed polylactic acid (PLA) and the concept of 4D printing onto nylon fabrics for the creation of smart textiles

3D printing is an ever growing industry that provides many benefits to the advanced manufacturing and design industry. However, parts tend to be static, rigid, and lack multi-purpose use. Recently, a new technology has emerged that uses 3D printing to print parts with the ability to change shape over time when exposed to different external stimuli. This new technology has been called 4D printing. Creation of a new material that is capable of changing shape when exposed to different stimuli and possess the ability to be 3D printed can be a difficult and a long process. Due to this strenuous process, the potential of a common fused deposition modelling material, poly(lactic) acid (PLA), for use in 4D printing is investigated and the concept of combining PLA with nylon fabric for the creation of smart textiles is explored. PLA possesses thermal shape memory behaviour and maintains these abilities when combined with nylon fabric that can be thermomechanically trained into temporary shapes and return to their permanent shapes when heated.     

Improving the sampling resolution of periodic signals by using controlled sampling interval method

A simple and reliable controlled sampling interval (CSI) method is proposed for improving the sampling resolution of periodic signals of analog-to-digital converters (ADC). The proposed CSI method uses K periods to obtain P sampling points. By combining these P sampling points into one period interval, the period is virtually sampled with a high number of samples. This new technique includes two main stages: (i) determining the values of P and K, and (ii) performing the sampling and signal recombination process. Experimental results show that the proposed CSI method, which requires no additional hardware, improves the sampling resolution of periodic signals.