4,401 research outputs found
Evaluation of the Beacon Community Centers Middle School Initiative: Report on the First Year
Evaluates the first year of an initiative to provide structured after-school and summer programs for fifth- through eighth-graders. Examines the centers' adaptation to the new focus, enrollment and participation levels, and implementation of core goals
Shrinking binary and planetary orbits by Kozai cycles with tidal friction
At least two arguments suggest that the orbits of a large fraction of binary
stars and extrasolar planets shrank by 1-2 orders of magnitude after formation:
(i) the physical radius of a star shrinks by a large factor from birth to the
main sequence, yet many main-sequence stars have companions orbiting only a few
stellar radii away, and (ii) in current theories of planet formation, the
region within ~0.1 AU of a protostar is too hot and rarefied for a Jupiter-mass
planet to form, yet many "hot Jupiters" are observed at such distances. We
investigate orbital shrinkage by the combined effects of secular perturbations
from a distant companion star (Kozai oscillations) and tidal friction. We
integrate the relevant equations of motion to predict the distribution of
orbital elements produced by this process. Binary stars with orbital periods of
0.1 to 10 days, with a median of ~2 d, are produced from binaries with much
longer periods (10 d to 10^5 d), consistent with observations indicating that
most or all short-period binaries have distant companions (tertiaries). We also
make two new testable predictions: (1) For periods between 3 and 10 d, the
distribution of the mutual inclination between the inner binary and the
tertiary orbit should peak strongly near 40 deg and 140 deg. (2) Extrasolar
planets whose host stars have a distant binary companion may also undergo this
process, in which case the orbit of the resulting hot Jupiter will typically be
misaligned with the equator of its host star.Comment: Submitted to ApJ; 18 pages, 10 figure
Use and Management of Medications for Children Diagnosed with Attention Deficit Hyperactivity Disorder (ADHD)
Numerical Prediction and Wind Tunnel Experiment for a Pitching Unmanned Combat Air Vehicle
The low-speed flowfield for a generic unmanned combat air vehicle (UCAV) is investigated both experimentally and numerically. A wind tunnel experiment was conducted with the Boeing 1301 UCAV at a variety of angles of attack up to 70 degrees, both statically and with various frequencies of pitch oscillation (0.5, 1.0, and 2.0 Hz). In addition, pitching was performed about three longitudinal locations on the configuration (the nose, 35% MAC, and the tail). Solutions to the unsteady, laminar, compressible Navier–Stokes equations were obtained on an unstructured mesh to match results from the static and dynamic experiments. The computational results are compared with experimental results for both static and pitching cases. Details about the flowfield, including vortex formation and interaction, are shown and discussed, including the non-linear aerodynamic characteristics of the vehicle
False discovery rate smoothing
We present false discovery rate smoothing, an empirical-Bayes method for
exploiting spatial structure in large multiple-testing problems. FDR smoothing
automatically finds spatially localized regions of significant test statistics.
It then relaxes the threshold of statistical significance within these regions,
and tightens it elsewhere, in a manner that controls the overall
false-discovery rate at a given level. This results in increased power and
cleaner spatial separation of signals from noise. The approach requires solving
a non-standard high-dimensional optimization problem, for which an efficient
augmented-Lagrangian algorithm is presented. In simulation studies, FDR
smoothing exhibits state-of-the-art performance at modest computational cost.
In particular, it is shown to be far more robust than existing methods for
spatially dependent multiple testing. We also apply the method to a data set
from an fMRI experiment on spatial working memory, where it detects patterns
that are much more biologically plausible than those detected by standard
FDR-controlling methods. All code for FDR smoothing is publicly available in
Python and R.Comment: Added misspecification analysis, added pathological scenario
discussions, additional comparisons, new graph fused lasso algorith
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Buildout density projections for the West Corvallis Growth Management Project
Benton County, Oregon has been experiencing relatively high growth and
development during the last five years. This new growth has put a strain on urban and
rural development in the county. To cope with this growth, comprehensive plans,
zoning, and many other planning issues must be assessed and revised according to the
needs of the community. In 1992, the West Corvallis Growth Management Project
was established and intended to be the focus of new urban development in the county.
The incorporation of a planning tool, such as buildout density projections, will permit
better land use decisions to be made in the West Corvallis Project area. The buildout
density projections demonstrate how low, medium, or high growth and development
could affect the project area according to its current infrastructure limitations. As a
planning tool, density projection information will be important information for
determining how to re-delimit the zoning districts in the project area
The Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS): survey design, data catalogue and GAMA/WiggleZ spectroscopy
© 2016 The Authors. We present the Large Area Radio Galaxy Evolution Spectroscopic Survey (LARGESS), a spectroscopic catalogue of radio sources designed to include the full range of radio AGN populations out to redshift z ~ 0.8. The catalogue covers ~800 deg 2 of sky, and provides optical identifications for 19 179 radio sources from the 1.4 GHz Faint Images of the Radio Sky at Twenty-cm (FIRST) survey down to an optical magnitude limit of i mod < 20.5 in Sloan Digital Sky Survey (SDSS) images. Both galaxies and point-like objects are included, and no colour cuts are applied. In collaboration with the WiggleZ and Galaxy And Mass Assembly (GAMA) spectroscopic survey teams, we have obtained new spectra for over 5000 objects in the LARGESS sample. Combining these new spectra with data from earlier surveys provides spectroscopic data for 12 329 radio sources in the survey area, of which 10 856 have reliable redshifts. 85 per cent of the LARGESS spectroscopic sample are radio AGN (median redshift z = 0.44), and 15 per cent are nearby star-forming galaxies (median z = 0.08). Low-excitation radio galaxies (LERGs) comprise the majority (83 per cent) of LARGESS radio AGN at z < 0.8, with 12 per cent being high-excitation radio galaxies (HERGs) and 5 per cent radioloud QSOs. Unlike the more homogeneous LERG and QSO sub-populations, HERGs are a heterogeneous class of objects with relatively blue optical colours and a wide dispersion in mid-infrared colours. This is consistent with a picture in which most HERGs are hosted by galaxies with recent or ongoing star formation as well as a classical accretion disc
Leg weld fatigue cracks in anhydrous ammonia nurse tanks
In an accident in southwest Iowa, USA in 2012, an anhydrous ammonia nurse tank vented its entire cargo of 5500 L (1500 gallons) of liquid ammonia to the atmosphere. Follow-up study of the failed tank revealed a through-crack along a weld used to connect the tank to its running gear. Side-angle ultrasound examinations were performed on 532 used anhydrous ammonia nurse tanks to measure the locations, sizes, and orientations of flaw indications. The tanks examined had manufacture dates ranging from 1952 to 2011. A total of 83 indications were found in or near the leg welds of 50 of these 532 tanks. Several factors suggest that these indications are fatigue cracks, not the stress corrosion cracks more commonly detected in nurse tanks. These findings suggest that roughly 9% of the 200,000 nurse tanks in the U.S. nurse tank fleet may contain leg-weld fatigue cracks. Nurse tanks are the only large, pressurized packages for hazardous cargo that do not contain manways; thus, their interior walls cannot be inspected for flaws with magnetic particle or fluorescent dye penetrant methods. Since the tank interior is inaccessible, side-angle ultrasound is the only detection method capable of detecting cracks in nurse tanks initiating at both interior and exterior tank surfaces. For this reason, the authors recommend that side-angle ultrasound be considered for use in periodic nurse tank inspections
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