Underwater depth imaging using time-correlated single-photon counting.

A depth imaging system, based on the time-of-flight approach and the time-correlated single-photon counting (TCSPC) technique, was investigated for use in highly scattering underwater environments. The system comprised a pulsed supercontinuum laser source, a monostatic scanning transceiver, with a silicon single-photon avalanche diode (SPAD) used for detection of the returned optical signal. Depth images were acquired in the laboratory at stand-off distances of up to 8 attenuation lengths, using per-pixel acquisition times in the range 0.5 to 100 ms, at average optical powers in the range 0.8 nW to 950 µW. In parallel, a LiDAR model was developed and validated using experimental data. The model can be used to estimate the performance of the system under a variety of scattering conditions and system parameters.

Polymorph driven diversification of photosalient responses in a zinc(II) coordination complex.

A novel crystallographic form of a Zn(II) coordination complex [Zn(4-ohbz)2(4-nvp)2] (1-Form-III) (H4-ohbz = 4-hydroxybenzoic acid and 4-nvp = (E)-4-(1-naphthylvinyl)pyridine), undergoes a solid-state photochemical [2+2] cycloaddition reaction accompanied by a moderate photosalient effect, whereby single-crystals show cracking and splitting. This UV-induced cycloaddition accompanies a single-crystal to single-crystal transformation, allowing for continuous monitoring of the unit cell parameters. The new polymorph represents an intermediate form of the two previously reported crystallographic forms of [Zn(4-ohbz)2(4-nvp)2], and provides novel insight into moderating the magnitude of photosalient responses across polymorphic materials.

Predictors of chronic trauma-related symptoms in a community sample of New Zealand motor vehicle accident survivors.

This study examined 1,500 New Zealand community-residing adults for involvement in serious motor vehicle accident (MVA) and the development of trauma-related symptomatology. The incidence of MVA was 11 %. More than 50 % of the accident victim sub-sample reported hyperarousal, with exaggerated startle, intrusive recollections, situational avoidance, emotional reactivity, and cognitive avoidance. The high incidence of trauma-related symptoms is noteworthy given 59 % of victims reported sustaining no or mild accident injury, and only 27 % were admitted to hospital for severe injury. Trauma-related symptoms were related to measures of injury severity, psychological and social functioning, and persistent medical problems. Pre- and post-accident factors, that is, experience of additional trauma, experience of stressful life events and post-accident social contact were the most important predictors of trauma-related symptoms severity. This study discusses the importance of examining trauma-related symptoms rather than using categorical diagnostic criteria (i.e., post-traumatic stress disorder, PTSD) as a sole means of characterizing the psychological impact of MVA.

Edge detection of the radiation field in double exposure portal images using a curve propagation algorithm.

An accurate detection of the radiation field is crucial to 3D conformal radiotherapy (3D-CRT). Automated techniques to detect the field edges on double exposure portal images have previously focused on thresholding techniques. In this paper, we present a new approach based on a curve propagation technique (the Fast Marching method) which proves to be more effective at detecting the radiation field than its thresholding counterpart. The comparison of both techniques in terms of computational speed and effectiveness of the detection is presented using complex images with non-homogeneous intensity levels inside the radiation field, and gradual variations in intensity level at the field boundaries. Results show that our Fast Marching method is easier to automate, and converges faster to the boundaries of the segmented radiation field. The computation time of the Fast Marching technique is five times faster in typical portal images.

Art of war hidden in Kolmogorov's equations.

Here we discuss how Kolmogorov's work on turbulence can be used as the inspiration for a new description of battlefield dynamics. The method presented may also represent a new way of describing self-organizing dynamical systems, in place of conventional differential equation approaches. The key finding is that the rate of attrition in a battle appears to be a function of the fractal dimension of the opposing forces. It is suggested that, this being the case, the fractal dimension could be used as a surrogate to represent the organizational efficiency of one force relative to another, commonly called Command and Control.