2,717 research outputs found
Nitrogen Abundances and the Distance Moduli of the Pleiades and Hyades
Recent reanalyses of HIPPARCOS parallax data confirm a previously noted
discrepancy with the Pleiades distance modulus estimated from main-sequence
fitting in the color-magnitude diagram. One proposed explanation of this
distance modulus discrepancy is a Pleiades He abundance that is significantly
larger than the Hyades value. We suggest that, based on our theoretical and
observational understanding of Galactic chemical evolution, nitrogen abundances
may serve as a proxy for helium abundances of disk stars. Utilizing
high-resolution near-UV Keck/HIRES spectroscopy, we determine N abundances in
the Pleiades and Hyades dwarfs from NH features in the 3330 Ang region. While
our Hyades N abundances show a modest 0.2 dex trend over a 800 K Teff range, we
find the Pleiades N abundance (by number) is 0.13+/-0.05 dex lower than in the
Hyades for stars in a smaller overlapping Teff range around 6000 K; possible
systematic errors in the lower Pleiades N abundance result are estimated to be
at the <0.10 dex level. Our results indicate [N/Fe]=0 for both the Pleiades and
Hyades, consistent with the ratios exhibited by local Galactic disk field stars
in other studies. If N production is a reliable tracer of He production in the
disk, then our results suggest the Pleiades He abundance is no larger than that
in the Hyades. This finding is supported by the relative Pleiades-Hyades C, O,
and Fe abundances interpreted in the current context of Galactic chemical
evolution, and is resistant to the effects on our derived N abundances of a He
abundance difference like that needed to explain the Pleiades distance modulus
discrepancy. A physical explanation of the Pleiades distance modulus
discrepancy does not appear to be related to He abundance.Comment: Accepted for publication in the Publications of the Astronomical
Society of the Pacifi
Text Messaging in the Patient-Centered Medical Home to Improve Glucose Control and Retinopathy Screening.
Purpose: To evaluate the effectiveness of a text messaging program (TMP) to improve glucose control, retinopathy screening (RS) rates, and self-care behaviors in patients with uncontrolled type 2 diabetes.
Methods: A single-group design with a quasi-systematic random sample (n=20) received educational/exhortational text messages on their cellular phones for 3 months. Subjects, 12 of whom identified as a minority ethnicity, were mostly male, aged 27-73 years.
Results: Glucose control and RS rates improved significantly. Subjects (\u3e70%) reported changes in self-care behaviors.
Conclusion: Leveraging ubiquitous technology, a TMP for patients with limited access to healthcare education, holds promis
Like Day and NIght: On Becoming a Teacher in Two Distinct Professional Cultures in Rural Saskatchewan
Framed within ecological and institutional ethnography perspectives, and situated within a larger study of beginning teachers in the Canadian province of Saskatchewan, this paper focuses on the dramatically different experiences of one beginning teacher who happened to secure half-time contracts in two rural schools within commuting distance of one another. His account of these experiences and how he makes sense of them orient researchers to the broad social, economic, and material conditions that organize the mutually dependent work of parents and teachers. This analysis contributes to beginning teacher research by affirming the value of personal stories of learning to teach, moving beyond studies of individual adaptation to fixed notions of professional success, and opening to scrutiny the shared conditions of early and later career teachers as they are institutionally and discursively organized, thus promoting appreciation of the complexities of learning to teach attuned to variation in local rural circumstances
Assessing the Risk of 100-year Freshwater Floods in the Lamprey River Watershed of New Hampshire Resulting from Changes in Climate and Land Use
Blueprint for Iteratively Hardening Power Grids Employing Unified Power Flow Controllers
A stable electricity supply is vital for modern society. However, many parts of our power transmission grid are operating near their operational limits. Such stressed systems are vulnerable to cascading failures, where a few small faults can induce a cascade of failures potentially leading to a major blackout The unified power flow controller (UPFC), the most powerful highspeed, semi-conductor based power flow device, can be used as a theoretical model to study how these devices can be used to improve power grid resilience. The blueprint presented here can be used to iteratively identify critical weaknesses in power grids and to recommend a means of fixing these weaknesses via the installation of UPFCs. This approach to hardening the power transmission grid will make it less prone to blackouts and better able to forestall or reduce the severity of unavoidable blackouts
A swarm in July : Beekeeping perspectives on the Old English Wid Ymbe charm
Inscribed in the margins of an eleventh-century manuscript1 of Bede's Ecclesiastical History of the English People and crowded beneath a Latin prayer is a brief bit of advice for beekeepers in the event of a swarm (ymbe), a natural phenomenon in which a substantial portion of an older bee colony migrates en masse with a queen to establish a new colony. The following analysis of this enigmatic text has been inspired largely by three features central to John Miles Foley's vast body of work: interdisciplinarity, collaboration, and comparative research. While the eight lines of alliterative verse that constitute the greater portion of this swarm charm have assured its standing within canonical Old English literature, its insights into traditional apiary practices of Anglo-Saxon England make it equally appropriate subject matter for studies in folklore or even animal science. It is precisely such unlikely intersections that have long served as foci for the transdisciplinary work of John Foley, and it is thus that we now choose it as the subject of analysis for a volume in his honor.2Issue title: Festschrift for John Miles Foley. This article belongs to a special issue of Oral Tradition published in honor of John Miles Foley's 65th birthday and 2011 retirement. The surprise Festschrift, guest-edited by Lori and Scott Garner entirely without his knowledge, celebrates John's tremendous impact on studies in oral tradition through a series of essays contributed by his students from the University of Missouri-Columbia (1979-present) and from NEH Summer Seminars that he has directed (1987-1996). Quotation marks removed to ensure alphabetical order. Title difference as follows; "A Swarm in July" : Beekeeping Perspectives on the Old English Wid Ymbe Char
Is Social Media a Threat or Can It Be a Trusted Agent?
There is a prevailing belief within the United States Department of Defense (DOD) that social media is a threat to national security, leading to restrictions in workplace use of social-media applications. However, instead of dismissing social media as a threat, leaders should be asking whether or not the information received via social media can be trusted, thus leveraging the information-sharing capabilities of social media. This article presents a theoretical case for quantifying social media trustworthiness by exploring the factors that influence trust in social media and proposing a trust framework to be used to quantify trustworthiness
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Reactions of C+ + Cl-, Br-, and I--A comparison of theory and experiment.
Rate constants for the reactions of C+ + Cl-, Br-, and I- were measured at 300 K using the variable electron and neutral density electron attachment mass spectrometry technique in a flowing afterglow Langmuir probe apparatus. Upper bounds of <10-8 cm3 s-1 were found for the reaction of C+ with Br- and I-, and a rate constant of 4.2 ± 1.1 × 10-9 cm3 s-1 was measured for the reaction with Cl-. The C+ + Cl- mutual neutralization reaction was studied theoretically from first principles, and a rate constant of 3.9 × 10-10 cm3 s-1, an order of magnitude smaller than experiment, was obtained with spin-orbit interactions included using a semiempirical model. The discrepancy between the measured and calculated rate constants could be explained by the fact that in the experiment, the total loss of C+ ions was measured, while the theoretical treatment did not include the associative ionization channel. The charge transfer was found to take place at small internuclear distances, and the spin-orbit interaction was found to have a minor effect on the rate constant
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