RESUMEN
Classical Empirical Mode Decomposition (EMD) is a data-driven method used to analyze non-linear and non-stationary time series data. Besides being an adaptable method by its nature, EMD assumes that every data consists of oscillations of the intrinsic mode functions (IMF). EMD also requires the condition that IMFs which represent the characteristic structures in the data should show only a unique sub-characteristic of the data. However, in some cases, depending on the way the sub-characteristics which make up a sophisticated data coexist, the IMFs are able to be not unique. This is called the mode-mixing problem. Although there are many studies and successful methods (such as EEMD, CEEMDAN) for eliminating the mode-mixing problem, a limited number of studies exist on determining the presence of the aforementioned problem. In this study, a method for the determination of the mode-mixing problem is proposed. In the suggested method, the Itakura-Saito distance, which is a measurement of the similarity of stationary signals and based on Fourier spectrums, is modified by applying Kaiser filter onto short-time signals. The performance of the method is tested via various applications with simulated and real data, and the results show successful detection of the mode-mixing if it exists in time series.
RESUMEN
PURPOSE: Many complications during Le Fort I osteotomy are encountered during pterygomaxillary separation. The study aimed to evaluate the pterygomaxillary region in regards to the Le Fort I osteotomy using cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS: The CBCT images of 200 patients (100 males, 100 females) aged 18-78 years were evaluated measuring the thickness and width of the pterygomaxillary region, the location of the descending palatine artery, and the length of the pterygoid plates on the axial section. RESULTS: It has been determined that the distance between the descending palatine canal and the priform rim is longer in males (P=0.037). Medial plate was longer on the right (P=0.0001) and left (P=0.025) in females. The thickness of the pterygomaxillary region was longer in females (P=0.000). The distance between the pterygomaxillary fissure and the descending palatine canal was longer on the right (P=0.001). CONCLUSION: The pterygomaxillary region may have different anatomies that predispose to specific complications associated with Le Fort I osteotomy. Therefore, before surgery, the pterygomaxillary region should be examined with CBCT, and necessary precautions should be taken preoperatively considering the possible complications.