Wavelet Cycle Spinning Denoising of NDE Ultrasonic Signals Using a Random Selection of Shifts

Wavelets are a powerful tool for signal and image denoising. Most of the denoising applications in different fields were based on the thresholding of the discrete wavelet transform (DWT) coefficients. Nevertheless, DWT transform is not a time or shift invariant transform and results depend on the selected shift. Improvements on the denoising performance can be obtained using the stationary wavelet transform (SWT) (also called shift-invariant or undecimated wavelet transform). Denoising using SWT has previously shown a robust and usually better performance than denoising using DWT but with a higher computational cost. In this paper, wavelet shrinkage schemes are applied for reducing noise in synthetic and experimental non-destructive evaluation ultrasonic A-scans, using DWT and a cycle-spinning implementation of SWT. A new denoising procedure, which we call random partial cycle spinning (RPCS), is presented. It is based on a cycle-spinning over a limited number of shifts that are selected in a random way. Wavelet denoising based on DWT, SWT and RPCS have been applied to the same sets of ultrasonic A-scans and their performances in terms of SNR are compared. In all cases three well known threshold selection rules (Universal, Minimax and Sure), with decomposition level dependent selection, have been used. It is shown that the new procedure provides a good robust denoising performance, without the DWT fluctuating performance, and close to SWT but with a much lower computational cost.This work was partially supported by Spanish MCI Project DPI2011-22438San Emeterio Prieto, JL.; Rodríguez-Hernández, MA. (2015). Wavelet Cycle Spinning Denoising of NDE Ultrasonic Signals Using a Random Selection of Shifts. 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Learning Medical Pharmacology through Role-Playing Method

Background and Objective: Traditional methods of medical education, despite being easy to implement, do not have long-lasting efficiency. The main aim of this study is to use the help of the learners to teach parts of the medical pharmacology course using role-playing pedagogy. This was done for the first time in Babol University of Medical Sciences with the cooperation of medical students who entered the university in 2016. Methods: Students were divided into 5 groups and a group leader was introduced for each group. Five topics were selected and corresponding scenarios were written. There were three to seven people in each group. The physician together with the hypothetical resident or student examined the patient's problems and prescribed medicine and gave them the necessary recommendations. All participants were given a pre-test and a post-test, and then the findings were statistically analyzed. Findings: 101 students (49 girls and 52 boys) with a mean age of 21.43±1.14 years participated in the study. Except for the topic of poisoning, the mean difference in pre- and post-test scores of female students was lower than that of male students. For example, this difference was observed in the topic of Parkinsonism (p<0.0001). All students involved in the performance obtained better grades in the same topics compared to other students (88.15 vs. 59.71 out of 100). 74% of female students and 79% of male students expressed satisfaction with the implementation of this method. Conclusion: According to the findings, this method has increased the motivation to learn the medical pharmacology course and stabilize the course topics. Therefore, its implementation in difficult courses with diverse and voluminous content not only helps them to learn better, but also helps them maintain their enthusiasm and increase motivation to learn more and consolidate what they have learned