The traditional method for studying non-stationary signals is spectrogram based on the short-time Fourier transform (STFT). The well known limitation of the STFT is the inherent trade-off between time and frequency resolution. The Wigner-Ville (WV) distribution has the best time-frequency resolution, but its draw Back is generating cross-terms. The matching pursuit (MP) distribution based on using the Gaussian atom is always positive, does not include crossterm, and has convenient resolution. In this paper, we have shown in addition to the known properties, the MP distribution can also remove the additive noise inherently. On the other words, we are able to remove the noise just by limiting the algorithm iterations and without paying any additional cost. Although the MP distribution based on using the Gaussian atoms is always positive and it has convenient resolution, according to the MP the time marginal and the frequency marginal will not be obtained accurately. In this paper, it has been shown that by implementing the minimum cross entropy (MCE) technique according to the MP distribution as a priory positive distribution, the new extracted distribution has the most similarity to the MP distribution and it also satisfies the correct time and frequency marginal.

In order to determine the effect of root canal sealer on microleakage of obturated root canals by lateral condensation technique (LCT)-with and without tug-Back (TB), seventy extracted single root canal teeth were examined. After preparation of root canal with step-Back technique, teeth were divided to six groups as follows: 5 teeth as positive control group that obturated by LCT with gutta-perch without sealer. 5 teeth as negative control group in which entire root surfaces and apical foramen coated with nail varnish, and four experimental groups (each group consisted of 15 teeth). Group I ZOE with TB, group II ZOE without TB, group III Roth sealer with TB, and group IV Roth sealer without TB. Then the teeth were immerssed in Pelikan ink for 72 hours and weparated in two peices through vertical long axis. Stereomicroscope observation showed that TB groups (I & III) have statistically less microleakage than non TB groups (II & IV) (P<0.0001). There were no significant differences between two TB groups. Results also showed no relationship between root canal sealer and apical leakage with and without TB in both type of sealers.

Background: Low Back pain (LBP) is a global public health issue. Physiotherapy is one of the most imperative conservative approaches for LBP patients. Beliefs of physiotherapists are seen to have a significant impact on treatment choices,however, beliefs that are not based on current evidence may lead to erroneous clinical decision-making. The present study explored the beliefs of physiotherapy students about low Back pain. Methods: This cross-sectional study was designed to detect the presence of myths among Indian undergraduate physiotherapy students using a predesigned survey outlining the “, myths of Back pain. ”,Bachelor of Physiotherapy students from different academic years of various colleges across India’, s north zone participated in the study. Survey questions were designed to identify the myths related to disease pathophysiology, treatment, and diagnostic tools. Results: A total of 265 physiotherapy students participated in the study. Among the participants, 31. 7% were males, and 61. 3% were females. The data revealed that most physiotherapy students hold incorrect beliefs, with major myths being (1) LBP is caused by poor posture when sitting, standing, and lifting,(2) LBP will become persistent and deteriorate in later life,and (3) LBP is caused by weak core muscles, and having a strong core protects against future LBP. There were some differences in a few myths based on academic years. Conclusion: Physiotherapy students have wrong beliefs associated with LBP. Educational programs should work towards developing courses that dispel these erroneous "beliefs. "