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Bothell, WA, United States

Worthey G.,Washington State University | Tang B.,Washington State University | Serven J.,Bellevue College
Astrophysical Journal

Spectral data on early-type galaxies are analyzed for chemical abundance with an emphasis on obtaining detailed abundances for the elements O and Si in addition to C, N, Na, Mg, Ca, Fe, and Ba. The abundance trends with velocity dispersion fit preconceptions based upon previous Mg conclusions, namely, that larger galaxies have a higher alpha element to iron peak ratio indicative of a higher ratio of Type II to Type Ia supernova products. The heaviest alpha elements, Ca and Ti, do not participate in this trend, although this fact does not necessarily alter the basic picture given the uncertainties in nucleosynthetic yields. Elements that likely have significant contributions from intermediate-mass stars, namely, C, N, and Ba, also gain ground relative to Fe in massive galaxies at a modest level, with the Ba conclusion uncertain from our data alone. After the velocity dispersion trend is subtracted, [M/H], [N/Fe], [Na/Fe], [Mg/Fe], and [Ca/Fe] probably have cosmic scatter, and no quantity can be shown to not have cosmic scatter. © 2014. The American Astronomical Society. All rights reserved. Source

Gupta M.K.,Bhabha Atomic Research Center | Goel P.,Bhabha Atomic Research Center | Mittal R.,Bhabha Atomic Research Center | Choudhury N.,Bhabha Atomic Research Center | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics

We report studies on the vibrational and elastic behavior of lithium oxide, Li 2O, around its superionic transition temperature. Phonon frequencies calculated using the local density approximation and generalized gradient approximation schemes of ab initio density functional theory are in excellent agreement with the reported experimental data. Further, volume dependence of phonon dispersion relation was calculated, which indicated softening of zone boundary transverse acoustic phonon mode along [110] at the volume corresponding to the superionic transition in Li 2O. This instability of phonon mode could be a precursor leading to the dynamic disorder of the lithium sublattice. Empirical potential model calculations were carried out to deduce the probable direction of vacancy-assisted lithium movement by constructing a supercell consisting of 12000 atoms. The energy profile for lithium ion movement was computed at volumes corresponding to ambient and superionic regimes. The energy considerations along various symmetry directions indicated that [001] was the most favorable direction for lithium movement in the fast ion phase. This result corroborated our observation of dynamic instability in the transverse phonon mode along the (110) wave vector. Using molecular dynamics simulations, we studied the temperature variation of elastic constants, which showed a large decrease in C 11, consistent with known experimental observation. © 2012 American Physical Society. Source

Prekeges J.,Bellevue College
Journal of Nuclear Medicine Technology

Breast cancer has long been a significant cause of morbidity and mortality. Mammography is the first-line imaging examination used to detect breast cancer; it has high sensitivity but only moderate specificity. The currently used secondary imaging modalities, sonography and MRI, cannot weed out all the falsepositive lesions that mammography identifies as potentially malignant. Further, many patients do not image well on mammography so there is a significant need for alternative imaging methods. Recently, technologies using small-field, pixelated detectors optimized for breast imaging have become available for both single-photon-emitting and positron-emitting radiopharmaceuticals. This article addresses the construction and functionality of several detector types and their application to imaging of the breast. Technical aspects of nuclear breast imaging will be discussed briefly. The article concludes with an assessment of the position of nuclear medicine imaging of the breast within the overall diagnostic scheme for breast cancer detection. © by the Society of Nuclear Medicine, Inc. Source

Cultivated by non-professionals, do-it-yourself (DIY) interventions in urban space are gaining serious credibility in the professional design fields. But as these professionals take up the flag of small-scale and social justice-inspired action in design handbooks and art exhibits, what happens to the struggles that informed the tactics? This article presents the DIY urban tactics of Food Not Bombs as a counter case study that problematizes the recent professional attention given to DIY, tactical or spontaneous urbanism. Forged in a struggle against the structural violence of capitalism, and based in the use of public space for community meals, Food Not Bombs challenges de-politicized notions of tactical or DIY urbanism. © 2015 Taylor & Francis Source

Prekeges J.L.,Bellevue College
Journal of Nuclear Medicine Technology

Nuclear medicine technologists use nonimaging radiation detection instruments on a daily basis and routinely assess their performance in several ways. These instruments are simple to operate compared with imaging instruments but are also susceptible to misuse. After reviewing the theoretic basis for common mistakes and the importance of routine quality control, this continuing education article discusses pitfalls in the operation of dose calibrators, survey meters, scintillation detectors, and semiconductors. The article also reviews quality control procedures and ways in which these can be performed incorrectly. The goal of the article is to help technologists to spot and correct problems before they lead to errant results. © 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc. Source

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