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), van Dokkum (2001), Pych (2004) 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 detection of cosmic ray events, however, the popular van Dokkum algorithm exhibits the highest overall performance in terms of detection and cleaning.Comment: 12 pages, 4 figures, accepted for publication in PAS

Spring Hydrology of Colorado Bend State Park, Central Texas

Karst development in Ellenburger carbonates near Colorado Bend State Park in central Texas exhibits complex polygenetic origins, with porosity development dominated by an early hypogene phase that has subsequently been overprinted to varying degrees by epigene processes. Quarterly physicochemical and continuous thermal monitoring analyses of eight springs in the study area indicate that modern groundwater flow paths are highly variable. Springs exhibit patterns that range from shallow, distributed recharge into diffuse-flow dominated systems, to focused recharge into well-connected conduit systems, to deep-circulation systems that equilibrate with bedrock. All springs, except Sulphur Spring, exhibit physicochemical characteristics indicative of proximal epigenic groundwater flow through Ellenburger carbonates, while Sulphur Spring shows elevated temperature and dissolved-ion concentrations indicative of longer groundwater flow paths through deeper strata. The polygenetic nature of karst development in the Colorado Bend State Park has created an enhanced porosity structure which forms a complex modern groundwater flow network

Food Safety Posters for Safe Handling of Leafy Greens

This article describes food safety educational tools depicting safe handling of leafy greens that are available as downloadable posters to Extension educators and practitioners (www.extension.iastate.edu). Nine visual-based minimal-text colored posters in English, Chinese, and Spanish were developed for use when formally or informally educating foodservice workers about safely handling leafy greens. A three-phase methodology included the use of expert knowledge, microbial sampling, and observational study in Iowa and Kansas foodservice operations. Use of the posters was shown to have positive impacts on both microbial levels and food safety behaviors, suggesting that the posters can be useful tools for Extension personnel

Organic-Vapor-Liquid-Solid Deposition with an Impinging Gas Jet

A method for rapid, mass-efficient deposition of highly crystalline organic films under near ambient conditions of pressure and temperature is reported based on delivery of an organic precursor via an impinging gas jet to a substrate coated by a thin liquid solvent layer. Films of the organic semiconductor tetracene were deposited by sublimation into a flow of argon carrier gas directed at an indium-tin-oxide/glass substrate coated by a thin layer of bis(2-ethylhexyl)sebecate, and growth was followed in situ with optical microscopy. A fluid dynamics model is applied to account for the gas phase transport and aggregation, and the results compared to experiment. The combination of gas jet delivery with an organic-vapor-liquid-solid growth mechanism leads to larger crystals and lower nucleation densities than on bare surfaces, with markedly different nucleation and growth kinetics. An explanation based on enhanced solution-phase diffusivity and a larger critical nucleus size in the liquid layer is proposed to account for the differences

Accredited qualifications for capacity development in disaster risk reduction and climate change adaptation

Increasingly practitioners and policy makers working across the globe are recognising the importance of bringing together disaster risk reduction and climate change adaptation. From studies across 15 Pacific island nations, a key barrier to improving national resilience to disaster risks and climate change impacts has been identified as a lack of capacity and expertise resulting from the absence of sustainable accredited and quality assured formal training programmes in the disaster risk reduction and climate change adaptation sectors. In the 2016 UNISDR Science and Technology Conference on the Implementation of the Sendai Framework for Disaster Risk Reduction 2015–2030, it was raised that most of the training material available are not reviewed either through a peer-to-peer mechanism or by the scientific community and are, thus, not following quality assurance standards. In response to these identified barriers, this paper focuses on a call for accredited formal qualifications for capacity development identified in the 2015 United Nations landmark agreements in DRR and CCA and uses the Pacific Islands Region of where this is now being implemented with the launch of the Pacific Regional Federation of Resilience Professionals, for DRR and CCA. A key issue is providing an accreditation and quality assurance mechanism that is shared across boundaries. This paper argues that by using the United Nations landmark agreements of 2015, support for a regionally accredited capacity development that ensures all countries can produce, access and effectively use scientific information for disaster risk reduction and climate change adaptation. The newly launched Pacific Regional Federation of Resilience Professionals who work in disaster risk reduction and climate change adaptation may offer a model that can be used more widely