356 research outputs found

    Management Implications of Molt Migration by the Atlantic Flyway Resident Population of Canada Geese, Branta canadensis

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    We used satellite-tracked transmitters in 2001 and 2003 to document the timing, location, and extent of molt migrations by female Canada Geese (Branta canadensis) affiliated with the Atlantic Flyway Resident Population (AFRP) of Canada Geese that breed in the temperate region of eastern North America. Twenty-seven adult females were captured during the nesting period in late May and fitted with a satellite transmitter mounted either on a plastic neck collar or backpack harness. Nests of 24 birds were destroyed late in incubation to prevent renesting and ensure nest failure; three females did not have nests. Twelve of the 27 birds (44%) made a northward migration to molt in northern Quebec, Canada: seven to the eastern coast of Hudson Bay (58°12'N, 76°60'W), three to lowland areas east of James Bay (53°30'N, 79°02'W), and two to interior locations south of Ungava Bay (55°54'N, 68°24'W). Molt migrants were present in northern Quebec from June to September, a period that coincides with breeding ground aerial surveys and banding operations conducted for Atlantic Population (AP) Canada Geese that breed in this same region of northern Quebec. With >1 million AFRP geese estimated in the Atlantic Flyway, the potential exists for substantial numbers of yearling, sub-adult, and nest-failed or non-breeding adults to molt migrate to northern breeding areas and bias efforts to survey and mark AP geese. Within AFRP breeding areas, many local flocks have reached nuisance levels. We hypothesized that by inducing molt migration in breeding adults, through destruction of nests late in incubation, we would lessen recruitment, reduce numbers of summer resident adults with young, and increase adult mortality from hunting. However, molt migration behavior was not uniform throughout our study area. Molt migrants were from rural areas in New York, Pennsylvania, and Vermont, whereas marked birds that did not make molt migrations were from more coastal regions of the flyway. The 14 birds that did not make a molt migration remained within 60 km of their banding site. A genetic comparison of these two groups revealed no detectable differences. We conclude that failure to undergo a molt migration is likely attributed to the historical origin of captive-reared birds of mixed subspecies that comprise AFRP flocks in the eastern regions of the flyway and the availability of quality local habitat, distinct from brood-rearing areas, for molting

    Shock formation and the ideal shape of ramp compression waves

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    We derive expressions for shock formation based on the local curvature of the flow characteristics during dynamic compression. Given a specific ramp adiabat, calculated for instance from the equation of state for a substance, the ideal nonlinear shape for an applied ramp loading history can be determined. We discuss the region affected by lateral release, which can be presented in compact form for the ideal loading history. Example calculations are given for representative metals and plastic ablators. Continuum dynamics (hydrocode) simulations were in good agreement with the algebraic forms. Example applications are presented for several classes of laser-loading experiment, identifying conditions where shocks are desired but not formed, and where long duration ramps are desired

    Confrontation and the Utility of Rules

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    There is a good reason why evidence scholars continue to be fascinated and perplexed, and some courts continue at least to be perplexed, by the types of evidence that tend to be lumped together misleadingly under the headings nonassertive conduct or implied assertions. Evidence of this sort highlights a paradox of the prevailing law of hearsay. I believe that this paradox cannot be resolved without fundamentally transforming the structure of that law. Thus, while I agree - within the current framework - with many of the insights so ably stated in this Symposium, I think evidence scholars must devote their efforts to construction of a better structure

    Miniature exoplanet radial velocity array I: design, commissioning, and early photometric results

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    The MINiature Exoplanet Radial Velocity Array (MINERVA) is a US-based observational facility dedicated to the discovery and characterization of exoplanets around a nearby sample of bright stars. MINERVA employs a robotic array of four 0.7 m telescopes outfitted for both high-resolution spec- troscopy and photometry, and is designed for completely autonomous operation. The primary science program is a dedicated radial velocity survey and the secondary science objective is to obtain high precision transit light curves. The modular design of the facility and the flexibility of our hardware allows for both science programs to be pursued simultaneously, while the robotic control software provides a robust and efficient means to carry out nightly observations. In this article, we describe the design of MINERVA including major hardware components, software, and science goals. The telescopes and photometry cameras are characterized at our test facility on the Caltech campus in Pasadena, CA, and their on-sky performance is validated. New observations from our test facility demonstrate sub-mmag photometric precision of one of our radial velocity survey targets, and we present new transit observations and fits of WASP-52b—a known hot-Jupiter with an inflated radius and misaligned orbit. The process of relocating the MINERVA hardware to its final destination at the Fred Lawrence Whipple Observatory in southern Arizona has begun, and science operations are expected to commence within 2015

    Theoretical and experimental investigation of the equation of state of boron plasmas

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    We report a theoretical equation of state (EOS) table for boron across a wide range of temperatures (5.1×\times104^4-5.2×\times108^8 K) and densities (0.25-49 g/cm3^3), and experimental shock Hugoniot data at unprecedented high pressures (5608±\pm118 GPa). The calculations are performed with full, first-principles methods combining path integral Monte Carlo (PIMC) at high temperatures and density functional theory molecular dynamics (DFT-MD) methods at lower temperatures. PIMC and DFT-MD cross-validate each other by providing coherent EOS (difference <<1.5 Hartree/boron in energy and <<5% in pressure) at 5.1×\times105^5 K. The Hugoniot measurement is conducted at the National Ignition Facility using a planar shock platform. The pressure-density relation found in our shock experiment is on top of the shock Hugoniot profile predicted with our first-principles EOS and a semi-empirical EOS table (LEOS 50). We investigate the self diffusivity and the effect of thermal and pressure-driven ionization on the EOS and shock compression behavior in high pressure and temperature conditions We study the performance sensitivity of a polar direct-drive exploding pusher platform to pressure variations based on comparison of the first-principles calculations with LEOS 50 via 1D hydrodynamic simulations. The results are valuable for future theoretical and experimental studies and engineering design in high energy density research. (LLNL-JRNL-748227)Comment: 12 pages, 9 figures, 2 table

    Concentration and origin of lead (Pb) in liver and bone of Eurasian buzzards (Buteo buteo) in the United Kingdom.

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    Ingestion of lead (Pb) derived from ammunition used in the hunting of game animals is recognised to be a significant potential source of Pb exposure of wild birds, including birds of prey. However, there are only limited data for birds of prey in Europe regarding tissue concentrations and origins of Pb. Eurasian buzzards (Buteo buteo) found dead in the United Kingdom during an 11-year period were collected and the concentrations of Pb in the liver and femur were measured. Concentrations in the liver consistent with acute exposure to Pb were found in 2.7% of birds and concentration in the femur consistent with exposure to lethal levels were found in 4.0% of individuals. Pb concentration in the femur showed no evidence of consistent variation among or within years, but was greater for old than for young birds. The Pb concentration in the liver showed no effect of the birds' age, but varied markedly among years and showed a consistent tendency to increase substantially within years throughout the UK hunting season for gamebirds. The resemblance of the stable isotope composition of Pb from buzzard livers to that of Pb from the types of shotgun ammunition most widely-used in the UK increased markedly with increasing Pb concentration in the liver. Stable isotope results were consistent with 57% of the mass of Pb in livers of all of the buzzards sampled being derived from shotgun pellets, with this proportion being 89% for the birds with concentrations indicating acute exposure to Pb. Hence, most of the Pb acquired by Eurasian buzzards which have liver concentrations likely to be associated with lethal and sublethal effects is probably obtained when they prey upon or scavenge gamebirds and mammals shot using Pb shotgun pellets
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