489 research outputs found

    Definition of Throw-Away Detectors (TADs) and VLF antenna for the AMPS laboratory

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    A Throw Away Detector (TAD)/subsatellite to be used as an experiment platform for the test flights to map the EMI from the shuttle and during the AMPS science flights is defined. A range of instrument platforms of varying capabilities is examined with emphasis on the EMI test vehicle. The operational support requirements of TAD/subsatellites are determined. The throw away detector is envisioned as a simple instrument package for supporting specific experiments

    The Material Turn: Charles-Germain de Saint-Aubin and the Art of Embroidery in Louis XV’s France

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    This thesis examines Charles-Germain de Saint-Aubin and his prolific treatise, L’art du Brodeur— both of which elevated the status of eighteenth-century embroidery under the reign of Louis XV, as seen in the context of embroidered court dress, concepts of etiquette and the luxury guilds

    Have Lesser Scaup, Aythya affinis, Reproductive Rates Declined in Parkland Manitoba?

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    Long-term surveys indicate that the scaup populations have declined over the past 20 years, and that this is probably the result of decreases in Lesser Scaup (Aythya affinis) rather than Greater Scaup (Aythya marila) numbers. To identify factors possibly related to the decline, we estimated demographic parameters for a local population of Lesser Scaup at Erickson, Manitoba, that was well studied before declines occurred and compared these estimates to historic rates. On average, nests were initiated later than in the past, and recent estimates of nesting success and duckling survival were lower than historical estimates. Breeding-season survival of adult females was estimated as 72.6%, with most (83%) mortality occurring during nesting. Current estimates of demographic rates at Erickson are too low to maintain a stable local population, and suppressed reproductive rates might be the proximate cause of the local population decline

    Geophysical Research

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    Contains reports on two research projects.National Aeronautics and Space Administration (Grant NGR-22-009-131)National Aeronautics and Space Administration (Grant NGR-22-009-114)National Aeronautics and Space Administration (Contract NAS 12-436

    Quantifying extreme behaviour in geomagnetic activity

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    Understanding the extremes in geomagnetic activity is an important component in understanding just how severe conditions can become in the terrestrial space environment. Extreme activity also has consequences for technological systems. On the ground, extreme geomagnetic behavior has an impact on navigation and position accuracy and the operation of power grids and pipeline networks. We therefore use a number of decades of one-minute mean magnetic data from magnetic observatories in Europe, together with the technique of extreme value statistics, to provide a preliminary exploration of the extremes in magnetic field variations and their one-minute rates of change. These extremes are expressed in terms of the variations that might be observed every 100 and 200 years in the horizontal strength and in the declination of the field. We find that both measured and extrapolated extreme values generally increase with geomagnetic latitude (as might be expected), though there is a marked maximum in estimated extreme levels between about 53 and 62 degrees north. At typical midlatitude European observatories (55–60 degrees geomagnetic latitude), compass variations may reach approximately 3–8 degrees/minute, and horizontal field changes may reach 1000–4000 nT/minute, in one magnetic storm once every 100 years. For storm return periods of 200 years the equivalent figures are 4–11 degrees/minute and 1000–6000 nT/minute

    First results of material charging in the space environment

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    A satellite experiment, designed to measure potential charging of typical thermal control materials at near geosynchronous altitude, was flown as part of the SCATHA program. Direct observations of charging of typical satellite materials in a natural charging event ( 5 keV) are presented. The results show some features which differ significantly from previous laboratory simulations of the environment

    Harvest and Non-Harvest Mortality Relationships for Lesser Scaup Breeding in Southwestern Montana

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    Since the mid-to-late 1990s, lesser scaup (Aythya affinis) populations have remained more than 20% below the population goal set forth in the North American Waterfowl Management Plan.  Accordingly, considerable attention has been directed towards understanding what factors may be limiting their population, including the role of harvest.  Red Rock Lakes National Wildlife Refuge (RRL) in southwestern Montana is the site of a long-term study of lesser scaup ecology and demography.  Preliminary harvest estimates indicate that this population is harvested at rates similar to the continental population with juveniles experiencing an annual average harvest rate of 9.1% (95% CI = 7.7 - 10.7%) and adults an average annual harvest rate of 3.6% (95% CI = 2.2 - 6.1%).  Since 2005, ~1,300 female have been banded on the study site and an additional ~1,000 females have been nasal-marked.  In addition, ~1,400 resightings have been collected for nasal-marked hens on the study site and ~340 dead recoveries from our study population have been reported from Canada to Mexico.  With results obtained from multistrata models that utilize these multiple encounter types, I will present (1) estimates of harvest and natural mortality rates for female lesser scaup banded and nasal-marked at RRL from 2005-2016; (2) how non-harvest mortality varies in relation to harvest mortality over the same period; (3) an assessment of how these rates respond to changes in hunting regulations.  These results will be used to help inform lesser scaup harvest demography, a key structural uncertainty in current harvest models identified in the draft Scaup Conservation Action Plan

    Harvest and Non-Harvest Mortality Relationships for Lesser Scaup Breeding in Southwestern Montana

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    Since the mid-to-late 1990s, lesser scaup (Aythya affinis) populations have remained more than 20% below the population goal set forth in the North American Waterfowl Management Plan.  Accordingly, considerable attention has been directed towards understanding what factors may be limiting their population, including the role of harvest.  Red Rock Lakes National Wildlife Refuge (RRL) in southwestern Montana is the site of a long-term study of lesser scaup ecology and demography with data from which survival and harvest rates can be estimated using capture-mark-recapture statistical techniques.  The role of harvest in regulating duck population dynamics, including lesser scaup, is clouded with uncertainty.  Decades of research into the additive or compensatory nature of harvest mortality has yielded little consensus as to which of these hypotheses prevail in North American duck populations.  The most limiting factor to assessing these relationships stems from lacking estimates of population size during waterfowl hunting seasons.  We assessed the relationship between survival rates and harvest rates for lesser scaup females breeding at RRL for an 11 years, beginning in 2005.  Consistent with predictions of density dependence regulation of natural mortality rates during the non-breeding season, we found evidence suggesting adult female survival rates fluctuate in response to harvest regulations, an index of population size, and the total number of lesser scaup harvested in the Pacific and Central Flyways
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