12,638 research outputs found

    Microwave technique measures plasma characteristics

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    Plasma electron density and temperature distribution are measured by passing a high frequency millimeter wave through plasma. Variations in density and temperature are determined by measuring insertion loss as the plasma travels between the microwave transmitting and receiving antennas

    Differential ion pumping for vacuum deposition

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    Feasibility of differential ion pumping concept for reducing pressure during vacuum deposition of thin film

    Scattering of 42 MeV /6.7-pJ/ alpha particles from even isotopes of cadmium. Supplement 1 - Absolute cross sections

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    Absolute cross sections for scattering of 42 MeV alpha particles from even isotopes of cadmiu

    Elastic and inelastic scattering of 42-MeV alpha particles from even tellurium isotopes

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    Angular distributions of elastic and inelastic scattering of 42-MeV alpha particles measured for even tellurium isotope

    Gamma ray angular correlations following inelastic scattering of 42-MeV alpha particles from magnesium 24

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    Angular correlation between inelastically scattered alpha particles and gamma rays emitted in subsequent nuclear decay of magnesium 2

    The Role of Canids in Ritual and Domestic Contexts: New Ancient DNA Insights from Complex Hunter-Gatherer Sites in Prehistoric Central California

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    This study explores the interrelationship between the genus Canis and hunter–gatherers through a case study of prehistoric Native Americans in the San Francisco Bay-Sacramento Delta area. A distinctive aspect of the region\u27s prehistoric record is the interment of canids, variously classified as coyotes, dogs, and wolves. Since these species are difficult to distinguish based solely on morphology, ancient DNA analysis was employed to distinguish species. The DNA study results, the first on canids from archaeological sites in California, are entirely represented by domesticated dogs (including both interments and disarticulated samples from midden deposits). These results, buttressed by stable isotope analyses, provide new insight into the complex interrelationship between humans and canids in both ritual and prosaic contexts, and reveal a more prominent role for dogs than previously envisioned

    The Multiple Origin of Blue Straggler Stars: Theory vs. Observations

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    In this chapter we review the various suggested channels for the formation and evolution of blue straggler stars (BSSs) in different environments and their observational predictions. These include mass transfer during binary stellar evolution - case A/B/C and D (wind Roche-lobe overflow) mass transfer, stellar collisions during single and binary encounters in dense stellar cluster, and coupled dynamical and stellar evolution of triple systems. We also explore the importance of the BSS and binary dynamics in stellar clusters. We review the various observed properties of BSSs in different environments (halo and bulge BSSs, BSSs in globular clusters and BSSs in old open clusters), and compare the current observations with the theoretical predictions for BSS formation. We try to constrain the likely progenitors and processes that play a role in the formation of BSSs and their evolution. We find that multiple channels of BSS formation are likely to take part in producing the observed BSSs, and we point out the strengths and weaknesses of each the formation channel in respect to the observational constraints. Finally we point out directions to further explore the origin of BSS, and highlight eclipsing binary BSSs as important observational tool.Comment: Chapter 11, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe
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