2,973 research outputs found
Using Text Analysis Tools to Improve Reference FAQs
A team of WSU reference librarians regularly reviews email reference questions and creates online FAQs as an aid to patrons and librarians. In the current project, text analysis tools were used to supplement the traditional process in an attempt to better understand the frequency and context of email reference queries. The presentation provides information on the text analysis tools used in the project, and presents several Q&A pairs developed using this process
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Visual Characterisation of Temporal Occupancy for Movement Ecology
Movement ecologists study aspects of animals' movement, behaviour, and the factors that might drive these. Temporal patterns of local occupancy often reveal the type of usage at a location. We present and apply temporal tile-maps that embed temporal visual encodings into cartographic representations, and do so in an interactive visual analysis context. This reveals spatial variation in temporal occupancy that allows places to be identified and distinguished according to their use by animals. We apply these to GPS data from tracking gulls and illustrate the application to movement ecology. The tool that implements this and data are available to download and use
Library inventory using a RFID wand: contribution of tag and book specific factors on the read rate
The Prompt Gamma-Ray and Afterglow Energies of Short-Duration Gamma-Ray Bursts
I present an analysis of the gamma-ray and afterglow energies of the complete
sample of 17 short duration GRBs with prompt X-ray follow-up. I find that 80%
of the bursts exhibit a linear correlation between their gamma-ray fluence and
the afterglow X-ray flux normalized to t=1 d, a proxy for the kinetic energy of
the blast wave ($F_{X,1}~F_{gamma}^1.01). An even tighter correlation is
evident between E_{gamma,iso} and L_{X,1} for the subset of 13 bursts with
measured or constrained redshifts. The remaining 20% of the bursts have values
of F_{X,1}/F_{gamma} that are suppressed by about three orders of magnitude,
likely because of low circumburst densities (Nakar 2007). These results have
several important implications: (i) The X-ray luminosity is generally a robust
proxy for the blast wave kinetic energy, indicating nu_X>nu_c and hence a
circumburst density n>0.05 cm^{-3}; (ii) most short GRBs have a narrow range of
gamma-ray efficiency, with ~0.85 and a spread of 0.14 dex; and
(iii) the isotropic-equivalent energies span 10^{48}-10^{52} erg. Furthermore,
I find tentative evidence for jet collimation in the two bursts with the
highest E_{gamma,iso}, perhaps indicative of the same inverse correlation that
leads to a narrow distribution of true energies in long GRBs. I find no clear
evidence for a relation between the overall energy release and host galaxy
type, but a positive correlation with duration may be present, albeit with a
large scatter. Finally, I note that the outlier fraction of 20% is similar to
the proposed fraction of short GRBs from dynamically-formed neutron star
binaries in globular clusters. This scenario may naturally explain the
bimodality of the F_{X,1}/F_{gamma} distribution and the low circumburst
densities without invoking speculative kick velocities of several hundred km/s.Comment: Submitted to ApJ; 9 pages, 2 figures, 1 tabl
The M33 Variable Star Population Revealed by Spitzer
We analyze five epochs of Spitzer Space Telescope/Infrared Array Camera
(IRAC) observations of the nearby spiral galaxy M33. Each epoch covered nearly
a square degree at 3.6, 4.5, and 8.0 microns. The point source catalog from the
full dataset contains 37,650 stars. The stars have luminosities characteristic
of the asymptotic giant branch and can be separated into oxygen-rich and
carbon-rich populations by their [3.6] - [4.5] colors. The [3.6] - [8.0] colors
indicate that over 80% of the stars detected at 8.0 microns have dust shells.
Photometric comparison of epochs using conservative criteria yields a catalog
of 2,923 variable stars. These variables are most likely long-period variables
amidst an evolved stellar population. At least one-third of the identified
carbon stars are variable.Comment: Accepted for publication in ApJ. See published article for full
resolution figures and electronic table
Mapping atomic and diffuse interstellar band absorption across the Magellanic Clouds and the Milky Way
Diffuse interstellar bands (DIBs) trace warm neutral and weakly-ionized
diffuse interstellar medium (ISM). Here we present a dedicated, high
signal-to-noise spectroscopic study of two of the strongest DIBs, at 5780 and
5797 \AA, in optical spectra of 666 early-type stars in the Small and Large
Magellanic Clouds, along with measurements of the atomic Na\,{\sc i}\,D and
Ca\,{\sc ii}\,K lines. The resulting maps show for the first time the
distribution of DIB carriers across large swathes of galaxies, as well as the
foreground Milky Way ISM. We confirm the association of the 5797 \AA\ DIB with
neutral gas, and the 5780 \AA\ DIB with more translucent gas, generally tracing
the star-forming regions within the Magellanic Clouds. Likewise, the Na\,{\sc
i}\,D line traces the denser ISM whereas the Ca\,{\sc ii}\,K line traces the
more diffuse, warmer gas. The Ca\,{\sc ii}\,K line has an additional component
at --220 km s seen towards both Magellanic Clouds; this may be
associated with a pan-Magellanic halo. Both the atomic lines and DIBs show
sub-pc-scale structure in the Galactic foreground absorption; the 5780 and 5797
\AA\ DIBs show very little correlation on these small scales, as do the
Ca\,{\sc ii}\,K and Na\,{\sc i}\,D lines. This suggests that good correlations
between the 5780 and 5797 \AA\ DIBs, or between Ca\,{\sc ii}\,K and Na\,{\sc
i}\,D, arise from the superposition of multiple interstellar structures.
Similarity in behaviour between DIBs and Na\,{\sc i} in the SMC, LMC and Milky
Way suggests the abundance of DIB carriers scales in proportion to metallicity.Comment: Accepted for publication in MNRA
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