4,563 research outputs found

    Large diameter astromast development, phase 1

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    Coilable-longeron lattice columns called Astromasts (trademark) were manufactured for a variety of spacecraft missions. These flight structures varied in diameter from 0.2 to 0.5 meter (9 to 19 in.), and the longest Astromast of this type deploys to a length of 30 meters (100 feet). A double-laced diagonal Astromast design referred to as the Supermast (trademark) which, because it has shorter baylengths than an Astromast, is approximately four times as strong. The longeron cross section and composite material selection for these structures are limited by the maximum strain associated with stowage and deployment. As a result, future requirements for deployable columns with high stiffness and strength require the development of both structures in larger diameters. The design, development, and manufacture of a 6.1-m-long (20-ft), 0.75-m-diameter (30-in.), double-laced diagonal version of the Astromast is described

    Alien Registration- Finley, William K. (Shirley, Piscataquis County)

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    https://digitalmaine.com/alien_docs/8492/thumbnail.jp

    Hybridism and the Rate of Change

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    Offshore Flight of Buffleheads, Bucephala albeola, After Twilight in Winter: An Anti-Predation Tactic?

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    In winter, on Vancouver Island, Buffleheads depart from coastal marine feeding habitat shortly after the onset of civil twilight. This precisely-timed phenomenon may have evolved in response to predation pressure from Peregrine Falcons, Falco peregrinus. The dual habitat requirements of Buffleheads in Shoal Harbour Migratory Bird Sanctuary (1931) and Sidney Channel Important Bird Area are to be included within the proposed Gulf Islands National Marine Conservation Area

    The Punctual Bufflehead, Bucephala albeola: Autumn Arrivals in Shoal Harbour Sanctuary, Vancouver Island, in Relation to Freeze-up

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    Buffleheads are punctual in their return to wintering grounds on the Pacific coast. First arrivals appeared in Shoal Harbour Migratory Bird Sanctuary, southeastern Vancouver Island, on the 288th day of the year on average (± S.D. 2.3; n = 10), that is, 15 October. This vanguard preceded the first peak influx by about 15–20 days, and a second influx by about 24–26 days. First arrivals usually appeared by mid-morning, and included singles (females on two occasions) and small flocks of up to eight. First arrivals may represent a photoperiodic threshold, whereas subsequent peak influxes represent climatic thresholds associated with freeze-up. The phenology of Bufflehead autumn migrations is a good proxy indicator of the advance of the zero degree isotherm, and thus of climatic variability. The timing of their autumn migrations does not appear to have changed in the last half of the twentieth century, consistent with evidence that freeze-up has not advanced. Monitoring of their migrations, in conjunction with shore-based observations of freeze-up, would validate one-dimensional thermodynamic models of freeze-up, and provide a more ecologically meaningful index of climate change, at minimal cost

    Development and Application of Operational Techniques for the Inventory and Monitoring of Resources and Uses for the Texas Coastal Zone

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    The author has identified the followed significant results. Techniques for interpretation of LANDSAT images were developed, along with a modified land use classification scheme

    Interspecific Mate Choice and Hybridism in the Bufflehead, Bucephala albeola

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    Observations of a male Bufflehead (Bucephela albeola) paired with a female Common Goldeneye (Bucephela clangula) in northern Alberta in 1995 and of a hybrid male Common Goldeneye × Bufflehead photographed near Victoria, British Columbia, in March 2009 provide the first combined evidence of interspecific mate choice and out-crossing in Bucephala albeola. Since 1999, there have been at least 10 unofficial records, including photographs, of Common Goldeneye × Bufflehead hybrids posted on the Internet, as well as 6 records of hybridization with Hooded Mergansers (Lophodytes cucullatus). In all cases, where evident in Common Goldeneye × Buffleheads, gold eyes and pink feet were expressed and social affiliation was with Common Goldeneyes, suggesting matrilineage with that species. Because most attention is given to the hybrid - and to male hybrids at that - rather than to the progenitors, the theory of mate attraction, through sexual imprinting of males, is biased toward the paternal viewpoint. It appears that there is more plasticity in mate choice, particularly by the female. The opportunity to observe mate choice is much rarer than the hybrid outcome, while the odds of the latter have increased many fold in the last decade due to advances in Internet communication and digital photography. This exercise illustrates the ability of the Internet to amplify the prevalence of rare phenomena many fold over historical records
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