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Abstract  

A procedure has been developed for the determination of 39 elements in a single sample of rock or mineral by neutron activation analysis. After the sample has been irradiated with neutrons, it is separated chemically into 12 groups for radioassay with one NaI(Tl) and two Ge(Li) detectors. Three chemists can complete the separations and sample preparations within 7 hrs after the end of the neutron irradiation. Carrier is added and a chemical yield is determined for each element. About two months are required to obtain complete data for a particular sample, but several samples can be analyzed concurrently. In a sample of typical igneous material weighing 0.5 g, half of the elements can be determined to better than ±5 per cent precision and accuracy, and fewer than a fifth with precision and accuracy poorer than ±25 per cent.

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Abstract  

The use of depleted uranium in military ordinance has led to an increasing need to determine isotope-specific uranium concentrations in environmental matrices. To this end, gamma-ray spectrometry, ICP-MS and INAA methods have been validated, in accordance with the ISO 17025 standard. Reporting limits of 0.21 (U-235) and 0.91 (U-238) ng/L were obtained by ICP-MS analysis of water. Higher reporting limits were obtained for INAA (U-238 only) validations of water and gamma-ray spectrometric validations of soil and water. Accredited methods have been used to determine uranium concentration and isotope ratio of samples obtained from the Defence Research and Development Canada Valcartier, Quebec.

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Community Ecology
Authors: M. L. Allen, M. J. Farmer, J. D. J Clare, E. R. Olson, J. Van Stappen, and T. R. Van Deelen

Carnivores are important components of ecological communities with wide-ranging effects that vary with carnivore size, natural history, and hunting tactics. Researchers and managers should strive to understand both the presence and distribution of carnivores within their local environment. We studied the carnivore guild in the Apostle Islands, where the distribution and occupancy of carnivores was largely unknown. We monitored 19 islands with 160 functioning camera traps from 2014-2017, from which we collected 203,385 photographs across 49,280 trap nights. We documented 7,291 total wildlife events with 1,970 carnivore events, and detected 10 of the 12 terrestrial carnivores found in Wisconsin. Detection rates for species were generally higher in summer than winter, except for coyotes (Canis latrans) and red foxes (Vulpes vulpes). Finitesample occupancy estimates for carnivores varied across islands, with mean estimated occupancy across islands varying from a high of 0.73 for black bears to a low of 0.21 for gray wolves. Of the potential island biogeography explanatory variables for carnivore occupancy we considered, island size was the most important, followed by distance to the mainland, and then interisland distance. We estimated that terrestrial carnivore species varied in the number of islands they were detected on from 1 island for gray wolves to 13 islands for black bears. Estimated carnivore richness across islands (i.e., the number of carnivores occupying an island) also varied substantively from 1 species on Michigan Island to 10 species on Stockton Island. Island size and connectivity between islands appear important for the persistence of the carnivore community in the Apostle Islands.

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