Evaluation of cosmic ray rejection algorithms on single-shot exposures

To maximise data output from single-shot astronomical images, the rejection of cosmic rays is important. We present the results of a benchmark trial comparing various cosmic ray rejection algorithms. The procedures assess relative performances and characteristics of the processes in cosmic ray detection, rates of false detections of true objects, and the quality of image cleaning and reconstruction. The cosmic ray rejection algorithms developed by Rhoads (2000, PASP, 112, 703), van Dokkum (2001, PASP, 113, 1420), Pych (2004, PASP, 116, 148), and the IRAF task xzap by Dickinson are tested using both simulated and real data. It is found that detection efficiency is independent of the density of cosmic rays in an image, being more strongly affected by the density of real objects in the field. As expected, spurious detections and alterations to real data in the cleaning process are also significantly increased by high object densities. We find the Rhoads' linear filtering method to produce the best performance in the detection of cosmic ray events; however, the popular van Dokkum algorithm exhibits the highest overall performance in terms of detection and cleaning.

'Putting up your Dukes': Statues, social memory and Duke Paoa Kahanamoku

Public statues that commemorate the lives and achievements of athletes are pervasive and influential forms of social memory in Western societies. Despite this important nexus between cultural practice and history making, there is a relative void of critical studies of statuary dedicated to athletes. This article will attempt to contribute to a broader understanding in this area by considering a bronze statue of Duke Paoa Kahanamoku, the Hawaiian Olympian, swimmer and surfer, at Waikīkī, Hawaii. This prominent monument demonstrates the processes of remembering and forgetting that are integral to acts of social memory. In this case, Kahanamoku's identity as a surfer is foregrounded over his legacy as a swimmer. The distillation and use of Kahanamoku's memory in this representation is enmeshed in deeper cultural forces about Hawaii's identity. Competing meanings of the statue's symbolism indicate its role as a 'hollow icon', and illustrate the way that apparently static objects representing the sporting past are in fact objects of the present.

Evaluation of different models to describe egg and pupal development of Xyleborus fornicatus Eichh. (Coleoptera: Scolytidae), the shot-hole borer of tea in Sri Lanka

Abstract Development data of eggs and pupae of Xyleborus fornicatus Eichh. (Coleoptera: Scolytidae), the shot-hole borer of tea in Sri Lanka, at constant temperatures were used to evaluate a linear and seven nonlinear models for insect development. Model evaluation was based on fit to data (residual sum of squares and coefficient of determination or coefficient of nonlinear regression), number of measurable parameters, the biological value of the fitted coefficients and accuracy in the estimation of thresholds. Of the nonlinear models, the Lactin model fitted experimental data well and along with the linear model, can be used to describe the temperature-dependent development of this species.