7,941 research outputs found

    Active rc filter permits easy trade-off of amplifier gain and sensitivity to gain

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    Passive RC network was designed with zeros of transmission in the right half of the complex frequency plane in the feedback loop of a simple negative-gain amplifier. The proper positioning provides any desired trade-off between amplifier gain and sensitivity to amplifier gain

    Perihelion

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    A thesis presented to the faculty of the Caudill College of Humanities at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Arts in English by C. Lynn Shaffer in April of 1995

    Corticosterone and foraging behaviour in a pelagic seabird

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    Because endocrine mechanisms are thought to mediate behavioral responses to changes in the environment, examining these mechanisms is essential for understanding how long-lived seabirds adjust their foraging decisions to contrasting environmental conditions in order to maximize their fitness. In this context, the hormone corticosterone (CORT) deserves specific attention because of its major connections with locomotor activities. We examined for the first time the relationships between individual CORT levels and measurements of foraging success and behavior using satellite tracking and blood sampling from wandering albatrosses (Diomedea exulans) before (pretrip CORT levels) and after (posttrip CORT levels) foraging trips during the incubation period. Plasma CORT levels decreased after a foraging trip, and the level of posttrip CORT was negatively correlated with individual foraging success, calculated as total mass gain over a foraging trip. Pretrip CORT levels were not linked to time spent at sea but were positively correlated with daily distance traveled and maximum range at sea. In this study, we were able to highlight the sensitivity of CORT levels to variation in energy intake, and we showed for the first time that individual CORT levels can be explained by variation in foraging success. Relationships between pretrip CORT levels and daily distance traveled and maximum range were independent of pretrip body mass, suggesting that slight elevations in pretrip CORT levels might facilitate locomotor activity. However, because both foraging behavior and pretrip CORT levels could be affected by individual quality, future experimental studies including manipulation of CORT levels are needed to test whether CORT can mediate foraging decisions according to foraging conditions

    An Investigation to Remotely Sense Mineral Leeching Through Soils

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    Satellite data on Earth\u27s surface provide a wealth of information on landscape conditions. I use Landsat data to determine an important geologic process that influences the composition of the soils. My project focusses on the experimental hypothesis that we can use plant vigor as a proxy to document mineral washing downslopes through soils. I constructed a Normalized Difference Vegetation Index (NDVI) composite image from Landsat data to help assess vegetation heath in my target location - a national park south of Mount St. Helens. This location was selected because of its steep inclines, dense undisturbed vegetation, and fertile soils. It is my hypothesis that as water trickles down through the soil it picks up and moves the dissolvable minerals downslope, therefore providing more minerals that aid vegetation growth and vigor at the bottom of the slopes. The NDVI analysis presented here provides data that can be used in a more detailed analysis of the same
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