Perioperative Complications in Percutaneous Nephrolithotomy: Predictive Risk Factors and Hemodynamic Alterations.

Background Percutaneous nephrolithotomy (PCNL) is one of the most frequently used methods of treating large and/or complex kidney stones. Despite the growing interest in this area, there are relatively few papers that report studies of the changes in hemodynamics in the perioperative period and the potential factors that might influence the patient's condition. This aspect, however, has not been well described in the current literature, although fluctuations in blood pressure, temperature, and electrolyte balance during surgery may also lead to development of complications.

Distribution of the ratio of two consecutive level spacings in orthogonal to unitary crossover ensembles.

The ratio of two consecutive level spacings has emerged as a very useful metric in investigating universal features exhibited by complex spectra. It does not require the knowledge of density of states and is therefore quite convenient to compute in analyzing the spectrum of a general system. The Wigner-surmise-like results for the ratio distribution are known for the invariant classes of Gaussian random matrices.

Measurement of large discontinuities using single white light interferogram.

White light interferometry is a widely used tool to extend the unambiguous measurement range of a monochromatic interferometer. In this work, we discuss Hilbert transformation analysis of a single white light interferogram acquired with a single-chip color CCD camera for step height measurement which lies beyond the unambiguous range of the monochromatic interferometry. The color interferogram is decomposed and phase maps for red, green, and blue components are calculated independently using Hilbert transformation.

Spectrally resolved phase-shifting interference microscopy: technique based on optical coherence tomography for profiling a transparent film on a patterned substrate.

Spectrally resolved white-light phase-shifting interference microscopy has been used for measurements of the thickness profile of a transparent thin-film layer deposited upon a patterned structure exhibiting steps and discontinuities. We describe a simple technique, using an approach based on spectrally resolved optical coherence tomography, that makes it possible to obtain directly a thickness profile along a line by inverse Fourier transformation of the complex spectral interference function.

Time average vibration fringe analysis using Hilbert transformation.

Quantitative phase information from a single interferogram can be obtained using the Hilbert transform (HT). We have applied the HT method for quantitative evaluation of Bessel fringes obtained in time average TV holography. The method requires only one fringe pattern for the extraction of vibration amplitude and reduces the complexity in quantifying the data experienced in the time average reference bias modulation method, which uses multiple fringe frames.