Parametric Power Spectral Density Analysis of Noise from Instrumentation in MALDI TOF Mass Spectrometry

Noise in mass spectrometry can interfere with identification of the biochemical substances in the sample. For example, the electric motors and circuits inside the mass spectrometer or in nearby equipment generate random noise that may distort the true shape of mass spectra. This paper presents a stochastic signal processing approach to analyzing noise from electrical noise sources (i.e., noise from instrumentation) in MALDI TOF mass spectrometry. Noise from instrumentation was hypothesized to be a mixture of thermal noise, 1/f noise, and electric or magnetic interference in the instrument. Parametric power spectral density estimation was conducted to derive the power distribution of noise from instrumentation with respect to frequencies. As expected, the experimental results show that noise from instrumentation contains 1/f noise and prominent periodic components in addition to thermal noise. These periodic components imply that the mass spectrometers used in this study may not be completely shielded from the internal or external electrical noise sources. However, according to a simulation study of human plasma mass spectra, noise from instrumentation does not seem to affect mass spectra significantly. In conclusion, analysis of noise from instrumentation using stochastic signal processing here provides an intuitive perspective on how to quantify noise in mass spectrometry through spectral modeling

Comparative evaluation of postoperative pain intensity after single-visit and multiple-visit retreatment cases: a prospective randomized clinical trial

Objective: This study was designed to evaluate postoperative pain after endodontic retreatment. Material and Methods: Asymptomatic, multi-rooted molar & premolar teeth requiring retreatment with 2–5 mm periapical lesions were included. Seventy-eight teeth were randomly placed in four groups (n=20): single-visit (control, group 1), Ledermix (group 2), metronidazole, ciprofloxacin, minocycline mixture (group 3), calcium hydroxide (group 4). The postoperative pain was recorded using a VAS at 6, 12, 24, and 48 h after retreatment. Statistical evaluation was performed using Two-Way Repeated Measures ANOVA and Tukey test. Results: Mild pain occurred in 67.5%, moderate in 30%, and flare-ups in 2.5%, and there was a significant difference between the groups (p<0.01). Significantly lower postoperative pain was observed in TAP and CaOH2 groups(p<0.05). In the 6, 12, and 24 h intervals, there was a significant difference in the pain levels (p<0.05). Conclusion: TAP and CaOH2 are effective for reducing postoperative pain after retreatment

QuaLe: A Quantum-Leap Inspired Model for Non-Stationary Analysis of NoC Traffic in Chip Multi-Processors

This paper identifies non-stationary effects in grid like Network-on-Chip (NoC) traffic and proposes QuaLe, a novel statistical physics-inspired model, that can account for non-stationarity observed in packet arrival processes. Using a wide set of real application traces, we demonstrate the need for a multi-fractal approach and analyze various packet arrival properties accordingly. As a case study, we show the benefits of our multifractal approach in estimating the probability of missing deadlines in packet scheduling for chip multiprocessors (CMPs).</p