100,171 research outputs found
The Directional Dependence of Apertures, Limits and Sensitivity of the Lunar Cherenkov Technique to a UHE Neutrino Flux
We use computer simulations to obtain the directional-dependence of the lunar
Cherenkov technique for ultra-high energy (UHE) neutrino detection. We
calculate the instantaneous effective area of past lunar Cherenkov experiments
as a function of neutrino arrival direction, and hence the
directional-dependence of the combined limit imposed by GLUE and the experiment
at Parkes.
We also determine the directional dependence of the aperture of future
planned experiments with ATCA, ASKAP and the SKA to a UHE neutrino flux, and
calculate the potential annual exposure to astronomical objects as a function
of angular distance from the lunar trajectory through celestial coordinates.Comment: 17 pages, 7 figures; Submitted to Astroparticle Physic
Physical Transport and Chemical Behavior of Dispersed Oil
During response operations, scientific information is provided to decision makers, such as the Federal On-Scene Coordinator (FOSC), state and federal trustees, and the public. The decision to use chemical dispersants during a response is made among all these parties, and during the Deepwater Horizon (DWH) oil spill the dispersant discussion included both surface and subsurface application of chemical dispersants. This paper is intended to provide perspective on research needs considered pre- and post-DWH oil spill related to response modeling and data collection needs for decision support of dispersant application and its potential effects. Given time constraints for implementing models and sampling strategies for response, requirements for data and types of questions to be addressed may be significantly different than requirements for research or damage assessment activities. At the time of this writing, just over a year after the successful response operations to cap the well, many studies are still in progress, and data are still being collected and evaluated to assess dispersant effectiveness and possible impacts. More information and research results will become available over the next months to years. Thus these research needs, as summarized for this workshop, should be evaluated again at a later time
Flight test to determine feasibility of a proposed airborne wake vortex detection concept
This investigation was conducted to determine the radial extent at which aircraft mounted flow vanes or roll rate gyros can sense the circulatory flow field that exists around the lift induced vortex system generated by an aircraft in flight. The probe aircraft was equipped with wingtip sensors for measuring angle of attack and angle of sideslip, and with a fuselage mounted gyroscope for measuring roll rate. Analysis of flight test data indicated that the vortex was detectable at a lateral distance of about 105 feet (best results) using unsophisticated equipment. Measurements were made from the centerline of the probe aircraft to the center of the nearest vortex with the probe aircraft flying between one half and one and one half miles behind the vortex generating aircraft
Probing the environment of emerin by Enhanced ascorbate peroxidase 2 (APEX2)-mediated proximity labeling.
Emerin is one of the best characterized proteins of the inner nuclear membrane, but can also occur at the level of the endoplasmic reticulum. We now use enhanced ascorbate peroxidase 2 (APEX2) to probe the environment of emerin. APEX2 can be used as a genetic tag that produces short-lived yet highly reactive biotin species, allowing the modification of proteins that interact with or are in very close proximity to the tagged protein. Biotinylated proteins can be isolated using immobilized streptavidin and analyzed by mass spectrometry. As an alternative to the standard approach with a genetic fusion of APEX2 to emerin, we also used RAPIDS (rapamycin- and APEX-dependent identification of proteins by SILAC), a method with improved specificity, where the peroxidase interacts with the protein of interest (i.e., emerin) only upon addition of rapamycin to the cells. We compare these different approaches, which, together, identify well-known interaction partners of emerin like lamin A and the lamina associated polypeptide 1 (LAP1), as well as novel proximity partners
How relative prices affect fuel use patterns in manufacturing : plant - level evidence from Chile
Some economists have urged reliance on fuel taxes and other fiscal incentives to reduce air pollution in semi-industrialized countries. They argue that policies that act on relative prices are easier to enforce than those based on emission monitoring, create less misallocation of resources, and are relatively free of the rent-seeking and corruption that accompany regulations administered at the plant level. To be effective, however, fuel specific taxes and subsidies must inspire manufacturers to significantly adjust their input use as relative prices change. Moreover, these policies must not create politically unacceptable income redistribution. The authors shed light on both issues by analyzing detailed panel data on Chilean manufacturing plants. Overall, their estimates suggest that there is substantial scope for fuel taxes to encourage fuel substitution, but that the response will be very uneven - not only across sectors but across producers of different sizes. Although others may be correct in arguing that fiscal incentives are easier to implement that are direct emission controls, the costs of adjustment are likely to be concentrated fairly narrowly for some fuels. The authors found bakeries, for example, to be very responsive to changes in the relative prices of alternative fuels. By contrast, energy demand in metal products plants appears to be very insensitive to relative prices, no matterwhat estimates are used. Meatpackers fall somewhere between the two - with little price responsiveness in electricity demand, but more in the demand for energy from other sources, especially if coherency-constrained figures are used. It seems that the effects of fuel taxes would depend in significant measure on the sectoral composition varies and some sectors have little flexibility.Energy and Environment,Economic Theory&Research,Transport and Environment,Access to Markets,Environmental Economics&Policies
Theoretical Predictions for Surface Brightness Fluctuations and Implications for Stellar Populations of Elliptical Galaxies
(Abridged) We present new theoretical predictions for surface brightness
fluctuations (SBFs) using models optimized for this purpose. Our predictions
agree well with SBF data for globular clusters and elliptical galaxies. We
provide refined theoretical calibrations and k-corrections needed to use SBFs
as standard candles. We suggest that SBF distance measurements can be improved
by using a filter around 1 micron and calibrating I-band SBFs with the
integrated V-K galaxy color. We also show that current SBF data provide useful
constraints on population synthesis models, and we suggest SBF-based tests for
future models. The data favor specific choices of evolutionary tracks and
spectra in the models among the several choices allowed by comparisons based on
only integrated light. In addition, the tightness of the empirical I-band SBF
calibration suggests that model uncertainties in post-main sequence lifetimes
are less than +/-50% and that the IMF in ellipticals is not much steeper than
that in the solar neighborhood. Finally, we analyze the potential of SBFs for
probing unresolved stellar populations. We find that optical/near-IR SBFs are
much more sensitive to metallicity than to age. Therefore, SBF magnitudes and
colors are a valuable tool to break the age/metallicity degeneracy. Our initial
results suggest that the most luminous stellar populations of bright cluster
galaxies have roughly solar metallicities and about a factor of three spread in
age.Comment: Astrophysical Journal, in press (uses Apr 20, 2000 version of
emulateapj5.sty). Reposted version has a minor cosmetic change to Table
Crustal deformation in great California earthquake cycles
Periodic crustal deformation associated with repeated strike slip earthquakes is computed for the following model: A depth L (less than or similiar to H) extending downward from the Earth's surface at a transform boundary between uniform elastic lithospheric plates of thickness H is locked between earthquakes. It slips an amount consistent with remote plate velocity V sub pl after each lapse of earthquake cycle time T sub cy. Lower portions of the fault zone at the boundary slip continuously so as to maintain constant resistive shear stress. The plates are coupled at their base to a Maxwellian viscoelastic asthenosphere through which steady deep seated mantle motions, compatible with plate velocity, are transmitted to the surface plates. The coupling is described approximately through a generalized Elsasser model. It is argued that the model gives a more realistic physical description of tectonic loading, including the time dependence of deep slip and crustal stress build up throughout the earthquake cycle, than do simpler kinematic models in which loading is represented as imposed uniform dislocation slip on the fault below the locked zone
Broughton Archipelago Clam Terrace Survey : final report
During a 1995 aerial video survey of the coastline
of Johnstone Strait, an unusual shoreline feature
was noted and termed “clam terraces” (inset)
because of the terrace-type morphology and the
apparent association with high clam productivity
on the sandflats. Typical alongshore lengths of the
terrace ridges are 20-50m, and across-shore widths
are typically 20-40m.
An area with an especially high density of clam
terraces was noted in the Broughton Archipelago,
between Broughton and Gilford Islands of
southeastern Queen Charlotte Strait. Clam terraces
in this area were inventoried from the aerial video
imagery to quantify their distribution. The terraces accounted for over 14 km of shoreline and
365 clam terraces were documented.
A three-day field survey by a coastal geomorphologist, archeologist and marine biologist was
conducted to document the features and determine their origin. Nine clam terraces were
surveyed. The field observations confirmed that: the ridges are comprised of boulder/cobblesized
material, ridge crests are typically in the range of 1-1.5m above chart datum, sandflats are
comprised almost entirely of shell fragments (barnacles and clams) and sandflats have very high
shellfish production. There are an abundance of shell middens in the area (over 175) suggesting
that the shellfish associated with the terraces were an important food source of aboriginal
peoples.
The origin of the ridges is unknown; they appear to be a relict feature in that they are not actively
being modified by present-day processes. The ridges may be a relict sea-ice feature, although the
mechanics of ridge formation is uncertain. Sand accumulates behind the ridge because the supply
rate of the shell fragments exceeds the dispersal rate in these low energy environments.
The high density areas of clam terraces correspond to high density areas of shell middens, and it
is probable that the clam terraces were subjected to some degree of modification by aboriginal
shellfish gatherers over the thousands of years of occupation in the region. (Document contains 39 pages
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