105 research outputs found

    Three-dimensional diving behavior of ringed seals

    Get PDF
    Thesis (Ph.D.) University of Alaska Fairbanks, 2000The three-dimensional movements of 13 freely diving ringed seals were recorded during the spring of 1990, 1991, 1992, 1996, and 1997 in the Canadian Arctic near Resolute Bay, Nunavut. These data were used to investigate the diving behavior of ringed seals more fully than was possible using previous data, which only recorded the vertical movements of diving animals (time-depth data). During a third of all dives, ringed seals focused much of their effort within a reduced volume, suggesting local search behavior within patches of prey. Local search occurred during descent, ascent, and bottom phases (time spent at depth between the end of descent and the beginning of ascent) of dives, but local search most commonly occurred during bottom phases. Location data from five seals were detailed enough to allow analysis of three-dimensional movements within individual dives. Behaviors were defined for the dives of these five seals based on the character of movements within the dives. Ringed seal dives included horizontally convoluted, travel, and exploration dives, but vertically convoluted, rest, and sit-and-wait foraging dives were not observed. Horizontally convoluted (presumed foraging), travel, and exploration dive behaviors were defined with similar frequency for V-shaped dives (dives with only descent and ascent phases) and U-shaped dives (dives with descent, bottom, and ascent phases). The lack of behavioral differences between dives with distinct time-depth profiles suggested that time-depth profiles were not a reliable means of classifying behavioral dive types for ringed seals

    Comparison of survey methods for estimating abundance of harbor seals (Phoca vitulina) in glacial fjords

    Get PDF
    The importance of glacial ice habitats to harbor seals (Phoca vitulina) in Alaska has become increasingly apparent. However, enumerating harbor seals hauled out on ice in glacial fjords has been difficult. At Johns Hopkins Inlet in Glacier Bay, Alaska, we compared a shore-based counting method to a large-format aerial photography method to estimate seal abundance. During each aerial survey, shore-based observers simultaneously counted seals from an observation post. Both survey methods incurred errors in double-counting and missing seals, especially when ice movements caused seals to drift between survey zones. Advantages of shore-based counts included the ability to obtain multiple counts for relatively little cost, distinguish pups from adults, and to distinguish mobile seals from shadows or glacial debris of similar size. Aerial photography provided a permanent record of each survey, allowing both a reconciliation of counts in overlapping zones and the documentation of the spatial distribution of seals and ice within the fjord

    Adaptation-Based Programming in Haskell

    Full text link
    We present an embedded DSL to support adaptation-based programming (ABP) in Haskell. ABP is an abstract model for defining adaptive values, called adaptives, which adapt in response to some associated feedback. We show how our design choices in Haskell motivate higher-level combinators and constructs and help us derive more complicated compositional adaptives. We also show an important specialization of ABP is in support of reinforcement learning constructs, which optimize adaptive values based on a programmer-specified objective function. This permits ABP users to easily define adaptive values that express uncertainty anywhere in their programs. Over repeated executions, these adaptive values adjust to more efficient ones and enable the user's programs to self optimize. The design of our DSL depends significantly on the use of type classes. We will illustrate, along with presenting our DSL, how the use of type classes can support the gradual evolution of DSLs.Comment: In Proceedings DSL 2011, arXiv:1109.032

    Longer lifespan in male mice treated with a weakly estrogenic agonist, an antioxidant, an α-glucosidase inhibitor or a Nrf2-inducer

    Get PDF
    The National Institute on Aging Interventions Testing Program (ITP) evaluates agents hypothesized to increase healthy lifespan in genetically heterogeneous mice. Each compound is tested in parallel at three sites, and all results are published. We report the effects of lifelong treatment of mice with four agents not previously tested: Protandim, fish oil, ursodeoxycholic acid (UDCA) and metformin – the latter with and without rapamycin, and two drugs previously examined: 17-α-estradiol and nordihydroguaiaretic acid (NDGA), at doses greater and less than used previously. 17-α-estradiol at a threefold higher dose robustly extended both median and maximal lifespan, but still only in males. The male-specific extension of median lifespan by NDGA was replicated at the original dose, and using doses threefold lower and higher. The effects of NDGA were dose dependent and male specific but without an effect on maximal lifespan. Protandim, a mixture of botanical extracts that activate Nrf2, extended median lifespan in males only. Metformin alone, at a dose of 0.1% in the diet, did not significantly extend lifespan. Metformin (0.1%) combined with rapamycin (14 ppm) robustly extended lifespan, suggestive of an added benefit, based on historical comparison with earlier studies of rapamycin given alone. The α-glucosidase inhibitor, acarbose, at a concentration previously tested (1000 ppm), significantly increased median longevity in males and 90th percentile lifespan in both sexes, even when treatment was started at 16 months. Neither fish oil nor UDCA extended lifespan. These results underscore the reproducibility of ITP longevity studies and illustrate the importance of identifying optimal doses in lifespan studies

    Ringed and bearded seal densities in the eastern Chukchi Sea, 1999–2000

    Get PDF
    Aerial surveys were conducted in 1999 and 2000 to estimate the densities of ringed (Phoca hispida) and bearded (Erignathus barbatus) seals in the eastern Chukchi Sea. Survey lines were focused mainly on the coastal zone within 37 km of the shoreline, with additional lines flown 148–185 km offshore to assess how densities of seals changed as a function of distance from shore. Satellite-linked time-depth recorders were attached to ringed seals in both years to evaluate the time spent basking on the ice surface. Haulout patterns indicated that ringed seals transitioned to basking behavior in late May and early June, and that the largest proportion of seals (60–68%) was hauled out between 0830 and 1530 local solar time. Ringed seals were relatively common in nearshore fast ice and pack ice, with lower densities in offshore pack ice. The average density of ringed seals was 1.91 seals km-2 in 1999 (range 0.37– 16.32) and 1.62 seals km-2 in 2000 (range 0.42–19.4), with the highest densities of ringed seals found in coastal waters south of Kivalina and near Kotzebue Sound. The estimated abundance of ringed seals for the entire study area was similar in 1999 (252,488 seals, SE=47,204) and 2000 (208,857 seals, SE=25,502). Bearded seals were generally more common in offshore pack ice, with the exception of high bearded seal numbers observed near the shore south of Kivalina. Bearded seal densities were not adjusted for haulout behavior, and therefore, abundance was not estimated. Unadjusted average bearded seal density was 0.07 seals km-2 in 1999 (range 0.011–0.393) and 0.14 seals km-2 in 2000 (range 0.009– 0.652). Levels of primary productivity, benthic biomass, and fast ice distribution may influence the distributions of ringed and bearded seals in the Chukchi Sea. Information on movement and haulout behavior of ringed and bearded seals would be very useful for designing future surveys

    Ecological Requirements for Pallid Sturgeon Reproduction and Recruitment in the Lower Missouri River: A Research Synthesis 2005–08

    Get PDF
    This report provides a synthesis of results obtained between 2005 and 2008 from the Comprehensive Sturgeon Research Program, an interagency collaboration between the U.S. Geological Survey, Nebraska Game and Parks Commission, U.S. Fish and Wildlife Service, and the U.S. Army Corps of Engineers’ Missouri River Recovery―Integrated Science Program. The goal of the Comprehensive Sturgeon Research Program is to improve fundamental understanding of reproductive ecology of the pallid sturgeon with the intent that improved understanding will inform river and species management decisions. Specific objectives include: • Determining movement, habitat-use, and reproductive behavior of pallid sturgeon; • Understanding reproductive physiology of pallid sturgeon and relations to environmental conditions; • Determining origin, transport, and fate of drifting pallid sturgeon larvae, and evaluating bottlenecks for recruitment of early life stages; • Quantifying availability and dynamics of aquatic habitats needed by pallid sturgeon for all life stages; and • Managing databases, integrating understanding, and publishing relevant information into the public domain
    • …
    corecore