14,564 research outputs found
The Deep SWIRE Field III. WIYN Spectroscopy
We present the results of spectroscopy using HYDRA on the WIYN 3.5m telescope
of objects in the deep SWIRE radio field. The goal of the project was to
determine spectroscopic redshifts for as many of the brighter objects in the
field as possible, especially those detected in the radio and at 24 microns.
These redshifts are primarily being used in studies of galaxy evolution and the
connection of that evolution to AGN and star-formation. Redshifts measured for
365 individual objects are reported. The redshifts range from 0.03 to 2.5,
mostly with z < 0.9. The sources were selected to be within the WIYN HYDRA
field of approximately 30' in radius from the center of the SWIRE deep field,
10h46m00s, 59d 01'00" (J2000). Optical sources for spectroscopic observation
were selected from a r-band image of the field. A priority list of
spectroscopic targets was established in the following order: 20cm detections,
24 micron detections, galaxies with r < 20 and the balance made up of fainter
galaxies in the field. We provide a table listing the galaxy positions,
measured redshift and error, and note any emission lines that were visible in
the spectrum. In practice almost all the galaxies with r < 19 were observed
including all of the radio sources and most of the 24 microns sources with r <
20 and a sample of radio sources which had fainter optical counterparts on the
r-band image.Comment: 6 pages, 3 tables, 2 figures, full electronic tables at
http://www.aoc.nrao.edu/~fowen/papers/SWIRE/WIYNpaper3/, accepted ApJ Suppl
Serie
A Five-year Spectroscopic and Photometric Campaign on the Prototypical alpha Cygni Variable and A-type Supergiant Star Deneb
Deneb is often considered the prototypical A-type supergiant, and is one of
the visually most luminous stars in the Galaxy. A-type supergiants are
potential extragalactic distance indicators, but the variability of these stars
needs to be better characterized before this technique can be considered
reliable. We analyzed 339 high resolution echelle spectra of Deneb obtained
over the five-year span of 1997 through 2001 as well as 370 Stromgren
photometric measurements obtained during the same time frame. Our spectroscopic
analysis included dynamical spectra of the H-alpha profile, H-alpha equivalent
widths, and radial velocities measured from Si II 6347, 6371. Time-series
analysis reveals no obvious cyclic behavior that proceeds through multiple
observing seasons, although we found a suspected 40 day period in two,
non-consecutive observing seasons. Some correlations are found between
photometric and radial velocity data sets, and suggest radial pulsations at two
epochs. No correlation is found between the variability of the H-alpha profiles
and that of the radial velocities or the photometry. Lucy (1976) found evidence
that Deneb was a long period single-lined spectroscopic binary star, but our
data set shows no evidence for radial velocity variations caused by a binary
companion.Comment: 49 pages, 9 figures, 5 tables, accepted for publication in the
Astronomical Journa
VLA 1.4GHz observations of the GOODS-North Field: Data Reduction and Analysis
We describe deep, new, wide-field radio continuum observations of the Great
Observatories Origins Deep Survey -- North (GOODS-N) field. The resulting map
has a synthesized beamsize of ~1.7" and an r.m.s. noise level of ~3.9uJy/bm
near its center and ~8uJy/bm at 15', from phase center. We have cataloged 1,230
discrete radio emitters, within a 40' x 40' region, above a 5-sigma detection
threshold of ~20uJy at the field center. New techniques, pioneered by Owen &
Morrison (2008), have enabled us to achieve a dynamic range of 6800:1 in a
field that has significantly strong confusing sources. We compare the 1.4-GHz
(20-cm) source counts with those from other published radio surveys. Our
differential counts are nearly Euclidean below 100uJy with a median source
diameter of ~1.2". This adds to the evidence presented by Owen & Morrison
(2008) that the natural confusion limit may lie near ~1uJy. If the Euclidean
slope of the counts continues down to the natural confusion limit as an
extrapolation of our log N - log S, this indicates that the cutoff must be
fairly sharp below 1uJy else the cosmic microwave background temperature would
increase above 2.7K at 1.4 GHz.Comment: Accepted for publication in ApJS. 16 pages, 19 figures. Radio data
and source list can be found at http://www.ifa.hawaii.edu/~morrison/GOODSN
Scalable squeezed light source for continuous variable quantum sampling
We propose a novel squeezed light source capable of meeting the stringent
requirements of continuous variable quantum sampling. Using the effective
interaction induced by a strong driving beam in the presence of the
response in an integrated microresonator, our device is compatible
with established nanophotonic fabrication platforms. With typical realistic
parameters, squeezed states with a mean photon number of 10 or higher can be
generated in a single consistent temporal mode at repetition rates in excess of
100MHz. Over 15dB of squeezing is achievable in existing ultra-low loss
platforms
Geophysical Methods: an Overview
Geophysics is expected to have a major role in lunar resource assessment when manned systems return to the Moon. Geophysical measurements made from a lunar rover will contribute to a number of key studies: estimating regolith thickness, detection of possible large-diameter lava tubes within maria basalts, detection of possible subsurface ice in polar regions, detection of conductive minerals that formed directly from a melt (orthomagmatic sulfides of Cu, Ni, Co), and mapping lunar geology beneath the regolith. The techniques that can be used are dictated both by objectives and by our abilities to adapt current technology to lunar conditions. Instrument size, weight, power requirements, and freedom from orientation errors are factors we have considered. Among the geophysical methods we believe to be appropriate for a lunar resource assessment are magnetics, including gradiometry, time-domain magnetic induction, ground-penetrating radar, seismic reflection, and gravimetry
Validity and practical utility of accelerometry for the measurement of in-hand physical activity in horses
Background:
Accelerometers are valid, practical and reliable tools for the measurement of habitual physical activity (PA). Quantification of PA in horses is desirable for use in research and clinical settings. The objective of this study was to evaluate a triaxial accelerometer for objective measurement of PA in the horse by assessment of their practical utility and validity.
Horses were recruited to establish both the optimal site of accelerometer attachment and questionnaire designed to explore owner acceptance. Validity and cut-off values were obtained by assessing PA at various gaits. Validation study- 20 horses wore the accelerometer while being filmed for 10Â min each of rest, walking and trotting and 5 mins of canter work. Practical utility study- five horses wore accelerometers on polls and withers for 18Â h; compliance and relative data losses were quantified.
Results:
Accelerometry output differed significantly between the four PA levels (P <0•001) for both wither and poll placement. For withers placement, ROC analyses found optimal sensitivity and specificity at a cut-off of <47 counts per minute (cpm) for rest (sensitivity 99.5 %, specificity 100 %), 967–2424 cpm for trotting (sensitivity 96.7 %, specificity 100 %) and ≥2425 cpm for cantering (sensitivity 96.0 %, specificity 97.0 %). Attachment at the poll resulted in optimal sensitivity and specificity at a cut-off of <707 counts per minute (cpm) for rest (sensitivity 97.5 %, specificity 99.6 %), 1546–2609 cpm for trotting (sensitivity 90.33 %, specificity 79.25 %) and ≥2610 cpm for cantering (sensitivity 100 %, specificity 100 %) In terms of practical utility, accelerometry was well tolerated and owner acceptance high.
Conclusion:
Accelerometry data correlated well with varying levels of in-hand equine activity. The use of accelerometers is a valid method for objective measurement of controlled PA in the horse
Quantum Deconstruction of a 5D SYM and its Moduli Space
We deconstruct the fifth dimension of the 5D SYM theory with SU(M) gauge
symmetry and Chern-Simons level k=M and show how the 5D moduli space follows
from the non-perturbative analysis of the 4D quiver theory. The 5D coupling
h=1/(g_5)^2 of the un-broken SU(M) is allowed to take any non-negative values,
but it cannot be continued to h<0 and there are no transitions to other phases
of the theory. The alternative UV completions of the same 5D SYM -- via M
theory on the C^3/Z_2M orbifold or via the dual five-brane web in type IIB
string theory -- have identical moduli spaces: h >= 0 only, and no flop
transitions. We claim these are intrinsic properties of the SU(M) SYM theory
with k=M.Comment: 46 Page
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