Analysis of stable isotope data: a K nearest-neighbors randomization test
Article Abstract:
Stable isotope analysis is increasingly being used in wildlife and ecological studies, including the dietary composition of animals. The mixing models used for such studies assume that each animal eats all possible food types and that prey types are different in bivariate space. Analyzing data of stable isotope ratios is problematical for such models because most sample sizes are small and randomly distributed. A new randomization test of data collected on the prey of American martens uses the K nearest-neighbors approach, which is shown to have high power, despite small sample sizes and low displacements.
Publication Name: The Journal of Wildlife Management
Subject: Zoology and wildlife conservation
ISSN: 0022-541X
Year: 1998
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High-strength alkali-resistant sintered SiC fibre stable to 2,200 deg C
Article Abstract:
SiC-based ceramics have been used in high-temperature composites and structural materials because they are stable at high temperatures. Silicon-carbide fiber can by produced through a sintering method, using an amorphous Si-Al-C-O precursor and a temperature of 1,800 deg C. The fibers possess a high tensile strength and better creep resistance at high temperatures than Hi-Niaclon and other commercial fibers based on SiC. The fibers also retain their mechanical peoperties following exposure to a solution of slat, and then being heated in air.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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Bracken ptaquiloside in milk
Article Abstract:
The bracken-fed cows produce milk containing ptaquiloside, a potent carcinogen binding covalently to nucleotides. The carcinogen splits uncoiled DNA, leading to tumours. The rate of bracken ingestion and the amount of ptaquiloside excreted are linearly correlated. Cattle exposed sporadically to bracken feeding produce pulses of ptaquiloside in milk. Therefore, ingestion of ptaquiloside milk by humans may cause tumors, which is supported by the fact that farmers in Costa Rica and other places with dense bracken develop gastric cancer.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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