Methods for point source analysis in high energy neutrino telescopes

Neutrino telescopes are moving steadily toward the goal of detecting astrophysical neutrinos from the most powerful galactic and extragalactic sources. Here we describe analysis methods to search for high energy point-like neutrino sources using detectors deep in the ice or sea. We simulate an ideal cubic kilometer detector based on real world performance of existing detectors such as AMANDA, IceCube, and ANTARES. An unbinned likelihood ratio method is applied, making use of the point spread function and energy distribution of simulated neutrino signal events to separate them from the background of atmospheric neutrinos produced by cosmic ray showers. The unbinned point source analyses are shown to perform better than binned searches and, depending on the source spectral index, the use of energy information is shown to improve discovery potential by almost a factor of two.     

Impact of lunar cycle and swell on the daily catch rate of western rock lobster (Panulirus cygnus) using time series modelling

The western rock lobster fishery is one of the most valuable single‐species fisheries in Australia, valued at AU$300 million per year. The impact of environmental factors such as lunar cycle and swell on the daily catch rate of the western rock lobster (Panulirus cynus) is of particular interest in the stock assessment and management of the fishery. The variation in daily catch rates was examined for two periods (migrating period November‐January, non‐migrating period February‐June), at different depths in three management zones for three categories of lobster (undersize, legal size, and setose). Regression and transfer function models for relationships between catch rates and environmental data were considered and compared. The lunar cycle has a significant impact on the daily catch rates with c. 30% lower catch rate during the full moon and c. 20% higher catches near the new moon. This impact occurs mainly during the non‐migrating period both in deep water (40–100 m) and shallow water (<40 m). The swell on the day before fishing was also shown to be significantly related to the catch rate with an increase of c. 10–15% for an increase in swell from light to moderate or moderate to high. These environmental factors can be used to standardise catch rates to provide an improved abundance index for stock assessment. Also, management closures are being considered for 3–5 days over the low catch rate, full moon period to reduce fishing costs and lower fishing effort.     

Astronomy at sea: Jim Wild's Cunard diary

When I saw an item on the RAS website seeking speakers for Cunard's Insights Lecture Programme, I was interested immediately. A chance to travel on some of the most famous ocean liners in the world and talk about my science to an enthusiastic audience? It seemed churlish not to apply!     

High spatial resolution data acquisition for the geosciences: kite aerial photography

This paper highlights the requirement for very high resolution (<0·25 m) elevation data for quantitative and qualitative morphometric analyses. Traditional techniques for high resolution data capture (e.g. airborne, heliborne) are prohibitively expensive for small studies and therefore a kite‐based platform was developed, in conjunction with a consumer non‐metric digital camera, for data capture. The combination of kite and digital camera is more generally termed kite aerial photography (KAP). The accuracy of data derived by digital photogrammetry and imagery acquired using a kite based non‐metric camera is assessed by three experiments: one on smooth terrain, one on tor terrain and one on a glaciofluvial esker. Ground control targets were surveyed at all three sites, with the imagery subsequently processed using the Leica Photogrammetry Suite. The results demonstrate that the method can extract a high number of sampling points at high accuracy, provided that there is suitable image texture across the site. However, final judgment concerning the suitability of derived data is dependent upon an understanding of measurement variability and user quantification of acceptable accuracy. Copyright © 2008 John Wiley & Sons, Ltd.     

An Injectable Apatite Permeable Reactive Barrier for In Situ 90Sr Immobilization

An injectable permeable reactive barrier (PRB) technology was developed to sequester ⁹⁰Sr in groundwater through the in situ formation of calcium‐phosphate mineral phases, specifically apatite that incorporates ⁹⁰Sr into the chemical structure. This injectable barrier technology extends the PRB concept to sites where groundwater contaminants are too deep or where site conditions otherwise preclude the application of more traditional trench‐emplaced barriers. An integrated, multiscale development and testing approach was used that included laboratory bench‐scale experiments, an initial pilot‐scale field test, and the emplacement and evaluation of a 300‐feet‐long treatability‐test‐scale PRB. The apatite amendment formulation uses two separate precursor solutions, one containing a Ca‐citrate complex and the other a Na‐phosphate solution, to form apatite precipitate in situ. Citrate is needed to keep calcium in solution long enough to achieve a more uniform and areally extensive distribution of precipitate formation. In the summer of 2008, the apatite PRB technology was applied as a 91‐m‐long (300 feet) PRB on the downgradient edge of a ⁹⁰Sr plume beneath the Hanford Site in Washington State. The technology was deployed to reduce ⁹⁰Sr flux discharging to the Columbia River. Performance assessment monitoring data collected to date indicate that the barrier is meeting treatment objectives (i.e., 90% reduction in ⁹⁰Sr concentration). The average reduction in ⁹⁰Sr concentrations at four downgradient compliance monitoring locations was 95% relative to the high end of the baseline range approximately 1 year after treatment, and continues to meet remedial objectives more than 4 years after treatment.     

Effect of the soil–pile–structure interaction in seismic analysis: case of liquefiable soils

The design of earthquake-resistant structures depends greatly on the soil–foundation–structure interaction. This interaction is more complex in the presence of liquefiable soils. Pile and rigid inclusion systems represent a useful practice to support structures in the presence of liquefiable soils in seismic zones. Both systems increase the bearing capacity of soil and allow reducing the settlements in the structure. Numerical models with a 3-storey reinforced concrete frame founded on inclusions systems (soil–inclusion–platform–structure) and pile systems (soil–pile–structure) were analyzed. Finite difference numerical models were developed using Flac 3D. Two different soil profiles were considered. A simple constitutive model for liquefaction analysis that relates the volumetric strain increment to the cyclic shear strain amplitude was utilized to represent the behavior of the sand, and the linear elastic perfectly plastic constitutive model with a Mohr–Coulomb failure criterion was used to represent the behavior of the earth platform. Two earthquakes were used to study the influence of the different frequency of excitation in the systems. The results were presented in terms of maximum shear forces distribution in the superstructure and spectrum response of each system. The efforts and displacements in the rigid elements (piles or rigid inclusions) were compared for the different systems. The bending and buckling failure modes of the pile were examined. The results show that the pile system, the soil profile and the frequency of excitation have a great influence on the magnitude and location of efforts and displacements in the rigid elements.

     

Geographic media literacy: an introduction

In a media saturated world of globalization, information flow and knowledge economies, an interesting paradox exists: geographic literacy appears to be on the decline while geographic information is on the rise. In this introduction to a collection of essays on geographies of the media, we explore this paradox and use Baudrillard’s (1994) work on Simulacra and Simulation to argue that increased mediated information does not produce more meaning, but rather leads to a catastrophe of meaning and the medium. Drawing from McLuhan’s axiom, “the medium is the message,” we posit that with more mediated information there is less meaningful information and as such we need to address geographic media literacy as a primary mode through which to address geographic literacy.

Mine tailings influencing soil contamination by potentially toxic elements

The potentially hazardous contents of mine tailings can pose a serious threat to the environment. Tailings dispersed around the abandoned Monica mine (Bustarviejo) in the Autonomous Region of Madrid (Central Spain) were studied to determine the concentration of several potential toxic elements and their geochemical impact in the surrounding soils. A total of 17 surface soil samples were collected from both mixed sulfide mine tailings sites and unmined soils, within a radius of 1900 m from the mine entrance. The processing of minerals (basically arsenopyrite, matildite and sphalerite) produced tailings with a pH as low as 2.9. Elements such as As, Cu, Zn, Cd, Pb, W, Ag, Fe were found in very high concentrations, contaminating the soil to varying degrees (these elements were sometimes 10- to 20-times higher in the tailings than in the unmined soils). Given its short distance and accessibility from such a large city as Madrid, it is of undeniable environmental and educational interest. Among other factors, there is a need for improvements to tailings management strategies.