Psychological predictors of pain during dental hygiene treatment

This study examined the role of catastrophizing (i.e. a tendency to exaggerate the threat value of potentially painful situations) in predicting pain experience during dental hygiene treatment. Participants in the research were 100 patients undergoing scaling and/or root planing procedures at Dalhousie University's Dental Clinic. Following treatment, participants completed the Pain Catastrophizing Scale, a measure of emotional distress, a pain scale, and the Dental Anxiety Scale-Revised. Participants who scored above the median on the Pain Catastrophizing Scale were classified as catastrophizers, participants who scored below the median were classified as noncatastrophizers. Results showed that catastrophizers reported significantly more dental anxiety, emotional distress and pain than noncatastrophizers; and that distress reactions were more pronounced in men that in women. Discussion focuses on the importance of addressing psychological factors in dental hygiene practice, particularly as they relate to reactions to dental hygiene procedures, and avoidance of dental care.     

Experimental realization of ‘universal homodyne tomography’ with a single local oscillator

We report preliminary experimental measurement of the twin-beam quantum state via optical homodyne tomography using a single local oscillator. The experiment is a realization of the recently reported ‘universal homodyne tomography’ technique. The results agree well with theoretical predictions and reveal the non-classical photon-number correlation between the signal and idler photons of the twin-beam state.     

A fast analog mean-timer

A circuit is described that determines the average of the transit time of light from an event in a scintillation counter to the two ends of that counter. The design offers superior time resolution and a novel gating scheme that significantly reduces circuit dead-time.     

Comments on PMS BDD generation in 'A BDD-based algorithm for Reliability Analysis of phased-mission systems'

This paper discusses some of the difficulties in the paper: "A BDD-based algorithm for reliability analysis of phased-mission systems" by X. Zang, H. Sun, and K. S. Trivedi.     

Lateral Migration Radiography

Lateral migration radiography (LMR) is a new form of Compton backscatter imaging (CBI) that utilizes both multiple-scatter and single-scatter photons. The LMR imaging modality uses two pairs of detectors. Each set has a detector that is uncollimated to predominantly image single-scatter photons and the other collimated to image predominantly multiple-scattered photons. This allows generation of two separate images, one containing primarily surface features and the other containing primarily subsurface features. These two images make LMR useful for imaging and identifying objects to a depth of several X-ray photon mean free paths even in the presence of unknown surface clutter or surface imperfections. The principles of LMR are demonstrated through Monte Carlo simulation of the photon transport. The Monte Carlo simulation results are verified with experimental measurements from an LMR system used for landmine detection. The presented research demonstrates the methodology for designing an LMR system, identifies methods for restoring and enhancing LMR images, and lays the foundation for the development of other applications of LMR, including, for example, the nondestructive examination of welds, castings, and composites.