22,435 research outputs found
Multispectral data analysis Final report
Contour maps and prediction lines demonstrating existence of water depth information in multispectral dat
Investigating the source – pathway – receptor – consequence framework for coastal flood system analyses
Extragalactic Foreground Contamination in Temperature-based CMB Lens Reconstruction
We discuss the effect of unresolved point source contamination on estimates
of the CMB lensing potential, from components such as the thermal
Sunyaev-Zel'dovich effect, radio point sources, and the Cosmic Infrared
Background. We classify the possible trispectra associated with such source
populations, and construct estimators for the amplitude and scale-dependence of
several of the major trispectra. We show how to propagate analytical models for
these source trispectra to biases for lensing. We also construct a
"source-hardened" lensing estimator which experiences significantly smaller
biases when exposed to unresolved point sources than the standard quadratic
lensing estimator. We demonstrate these ideas in practice using the sky
simulations of Sehgal et. al., for cosmic-variance limited experiments designed
to mimic ACT, SPT, and Planck
Enhanced Acoustic Emission in Relation to the Acoustic Halo Surrounding Active Region 11429
The use of acoustic holography in the high-frequency -mode spectrum can
resolve the source distributions of enhanced acoustic emissions within halo
structures surrounding active regions. In doing so, statistical methods can
then be applied to ascertain relationships with the magnetic field. This is the
focus of this study. The mechanism responsible for the detected enhancement of
acoustic sources around solar active regions has not yet been explained.
Furthermore the relationship between the magnetic field and enhanced acoustic
emission has not yet been comprehensively examined. We have used vector
magnetograms from the \Helioseismic and Magnetic Imager (HMI) on-board the
Solar Dynamics Observatory (SDO) to image the magnetic-field properties in the
halo. We have studied the acoustic morphology of an active region, with a
complex halo and "glories," and we have linked some acoustic properties to the
magnetic-field configuration. In particular, we find that acoustic sources are
significantly enhanced in regions of intermediate field strength with
inclinations no different from the distributions found in the quiet Sun.
Additionally we have identified a transition region between the active region
and the halo, in which the acoustic source power is hindered by inclined fields
of intermediate field strength. Finally, we have compared the results of
acoustic emission maps, calculated from holography, and the commonly used local
acoustic maps, finding that the two types of maps have similar properties with
respect to the magnetic field but lack spatial correlation when examining the
highest-powered regions.Comment: 19 pages, 8 figures, Accepted by Solar Physic
Aquatic Vegetation, Largemouth Bass and Water Quality Responses to Low-Dose Fluridone Two Years Post Treatment
Whole-lake techniques are increasingly being used to selectively
remove exotic plants, including Eurasian watermilfoil
(
Myriophyllum spicatum
L.). Fluridone (1-methyl-3-phenyl-
5-[3-(trifluoromethyl)phenyl]-4(1
H
)-pyridinone), a systemic
whole-lake herbicide, is selective for Eurasian watermilfoil
within a narrow low concentration range. Because fluridone
applications have the potential for large effects on plant assemblages
and lake food webs, they should be evaluated at
the whole-lake scale. We examined effects of low-dose (5 to 8
ppb) fluridone applications by comparing submersed plant
assemblages, water quality and largemouth bass (
Micropterus
salmoides
) growth rates and diets between three reference
lakes and three treatment lakes one- and two-years post treatment.
In the treatment lakes, fluridone reduced Eurasian watermilfoil
cover without reducing native plant cover, although
the duration of Eurasian watermilfoil reduction varied among
treatment lakes. (PDF has 11 pages.
Plasma measurements with the retarding potential analyser on OGO 6
Plasma measurements with retarding potential analyzer on OGO
Planar ion trap (retarding potential analyzer) experiment for atmosphere explorer
The retarding potential analyzer and drift meter were carried aboard all three Atmosphere Explorer spacecraft. These instruments measure the total thermal ion concentration and temperature, the bulk thermal ion velocity vector and some limited properties of the relative abundance of H(+), He(+), O(+) and molecular ions. These instruments functioned with no internal failures on all the spacecraft. On AE-E there existed some evidence for external surface contamination that damaged the integrity of the RPA sweep grids. This led to some difficulties in data reduction and interpretation that did not prove to be a disastrous problem. The AE-D spacecraft functioned for only a few months before it re-entered. During this time the satellite suffered from a nutation about the spin axis of about + or - 2 deg. This 2 deg modulation was superimposed upon the ion drift meter horizontal ion arrival angle output requiring the employment of filtering techniques to retrieve the real data
Two-way time transfers between NRC/NBS and NRC/USNO via the Hermes (CTS) satellite
At each station the differences were measured between the local UTC seconds pulse and the remote UTC pulse received by satellite. The difference between the readings, if station delays are assumed to be symmetrical, is two times the difference between the clocks at the two ground station sites. Over a 20-minute period, the precision over the satellite is better than 1 ns. The time transfer from NRC to the CRC satellite terminal near Ottawa and from NBS to the Denver HEW terminal was examined
Quenching Spin Decoherence in Diamond through Spin Bath Polarization
We experimentally demonstrate that the decoherence of a spin by a spin bath
can be completely eliminated by fully polarizing the spin bath. We use electron
paramagnetic resonance at 240 gigahertz and 8 Tesla to study the spin coherence
time of nitrogen-vacancy centers and nitrogen impurities in diamond from
room temperature down to 1.3 K. A sharp increase of is observed below the
Zeeman energy (11.5 K). The data are well described by a suppression of the
flip-flop induced spin bath fluctuations due to thermal spin polarization.
saturates at below 2 K, where the spin bath polarization
is 99.4 %.Comment: 5 pages and 3 figure
The hydrology of prehistoric farming systems in a central Arizona ecotone
The prehistoric land use and water management in the semi-arid Southwest was examined. Remote sensing data, geology, hydrology and biology are discussed along with an evaluation of remote sensing contributions, recommendations for applications, and proposed future remote sensing studies
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