34,413 research outputs found
SP-100 nuclear space power systems with application to space commercialization
The purpose of this paper is to familiarize the Space Commercialization Community with the status and characteristics of the SP-100 space nuclear power system. The program is a joint undertaking by the Department of Defense, the Department of Energy and NASA. The goal of the program is to develop, validate, and demonstrate the technology for space nuclear power systems in the range of 10 to 1000 kWe electric for use in the future civilian and military space missions. Also discussed are mission applications which are enhanced and/or enabled by SP-100 technology and how this technology compares to that of more familiar solar power systems. The mission applications include earth orbiting platforms and lunar/Mars surface power
The Siricidae (Hymenoptera: Symphyta) of Florida
The six species of Siricidae (Hymenoptera: Symphyta) occurring in Florida and one species of regulatory concern introduced to North America are reviewed. Included are diagnoses of Eriotremex formosanus (Matsumura), Sirex areolatus (Cresson), Sirex nigricornis Fabricius, Tremex columba (Linnaeus), Urocerus cressoni Norton, Urocerus taxodii (Ashmead) and Sirex noctilio (Fabricius). A key to species, photographs of morphological features, biological notes and distribution data are provided. For the species T. columba, S. nigricornis, U. taxodii, and U. cressoni, a total of eight new state records are presented
Alternative financial service providers and the spatial void hypothesis
This paper examines the use of alternative financial service providers (AFSPs) such as check-cashing outlets and pawnshops in Philadelphia, Montgomery, Delaware, and Allegheny counties. Also explores whether these providers are disproportionately serving minority and low-income areas.
Alternative financial service providers and the spatial void hypothesis: the case of New Jersey and Delaware
This paper continues the use of the spatial void hypothesis methodology to analyze the location of alternative financial service providers, such as check cashing outlets and pawn shops, in New Castle County, Delaware, and Atlantic, Mercer, Monmouth, and Passaic counties in New Jersey. Also explores whether these providers are disproportionately serving minority and low-income areas.
One year of monitoring the Vela pulsar using a Phased Array Feed
We have observed the Vela pulsar for one year using a Phased Array Feed (PAF)
receiver on the 12-metre antenna of the Parkes Test-Bed Facility. These
observations have allowed us to investigate the stability of the PAF
beam-weights over time, to demonstrate that pulsars can be timed over long
periods using PAF technology and to detect and study the most recent glitch
event that occurred on 12 December 2016. The beam-weights are shown to be
stable to 1% on time scales on the order of three weeks. We discuss the
implications of this for monitoring pulsars using PAFs on single dish
telescopes.Comment: 6 pages, 4 figures, 2 tables. Accepted for publication in PAS
The Long and the Short End of the Term Structure of Policy Rules
We first document a large secular shift in the estimated response of the entire term structure of interest rates to inflation and output in the United States. The shift occurred in the early 1980s. We then derive an equation that links these responses to the coefficients of the central bank's monetary policy rule for the short-term interest rate. The equation reveals two countervailing forces that help explain and understand the nature of the link and how its sign is determined. Using this equation, we show that a shift in the policy rule in the early 1980s provides an explanation for the observed shift in the term structure. We also explore a shift in the policy rule in the 2002-2005 period and its possible effect on long-term rates.
Structured Codes Improve the Bennett-Brassard-84 Quantum Key Rate
A central goal in information theory and cryptography is finding simple characterizations of optimal communication rates under various restrictions and security requirements. Ideally, the optimal key rate for a quantum key distribution (QKD) protocol would be given by a single-letter formula involving optimization over a single use of an effective channel. We explore the possibility of such a formula for the simplest and most widely used QKD protocol, Bennnett-Brassard-84 with one-way classical postprocessing. We show that a conjectured single-letter formula is false, uncovering a deep ignorance about good private codes and exposing unfortunate complications in the theory of QKD. These complications are not without benefit—with added complexity comes better key rates than previously thought possible. The threshold for secure key generation improves from a bit error rate of 0.124 to 0.129
Choice Experiments to Assess Farmers' Willingness to Participate in a Water Quality Trading Market
Interest has grown in Water Quality Trading (WQT) as a means to achieve water quality goals, with more than 70 such programs now in operation in the United States. Substantial evidence exists that nonpoint sources can reduce nutrient loading at a much lower cost than point sources, implying the existence of gains from trade. Despite the potential gains, however, the most commonly noted feature of existing WQT markets is low trading volume, with many markets resulting in zero trades. This paper evaluates one explanation for the lack of participation from agricultural nonpoint sources. We test for and quantify the intangible costs that may deter farmers from trading even if the monetary benefits from doing so outweigh the observable out-of-pocket costs. We do so by designing and implementing a series of choice experiments to elicit WQT trading behavior of Great Plains crop producers in different situations. Attributes of the choice experiment included market rules and features (e.g., application time and effort, penalties for violations, means of monitoring compliance) that may affect farmers willingness to trade. The choice experiments were conducted with a total of 135 producers at four locations in the state of Kansas between August 2006 and January 2007. A Random Parameters Logit model is appropriate to analyze the resulting data, revealing diversity in the way that the attributes affect farmers choices.Resource /Energy Economics and Policy,
Proper motions of collimated jets from intermediate-mass protostars in the Carina Nebula
We present proper motion measurements of 37 jets and HH objects in the Carina
Nebula measured in two epochs of H images obtained yrs apart
with HST/ACS. Transverse velocities in all but one jet are faster than km s, confirming that the jet-like H features identified by
Smith et al. (2010) trace outflowing gas. Proper motions constrain the location
of the jet-driving source and provide kinematic confirmation of the
intermediate-mass protostars that we identify for 20/37 jets. Jet velocities do
not correlate with the estimated protostar mass and embedded driving sources do
not have slower jets. Instead, transverse velocities (median km
s) are similar to those in jets from low-mass stars. Assuming a constant
velocity since launch, we compute jet dynamical ages (median yr).
If continuous emission from inner jets traces the duration of the most recent
accretion bursts, then these episodes are sustained longer (median
yr) than the typical decay time of an FU Orionis outburst. These jets can carry
appreciable momentum that may be injected into the surrounding environment. The
resulting outflow force, , lies between that measured in low- and
high-mass sources, despite the very different observational tracers used.
Smooth scaling of the outflow force argues for a common physical process
underlying outflows from protostars of all masses. This latest kinematic result
adds to a growing body of evidence that intermediate-mass star formation
proceeds like a scaled-up version of the formation of low-mass stars.Comment: accepted to MNRAS, 29 pages, 30 figures, 3 table
The natural resources of Agua Hedionda Lagoon
This report has been prepared under contract to and fully funded by the Office of Biological Services of the U. S. Fish and Wildlife Service. The goals and purpose of this federal office are to review the impact on fish and wildlife resources of land, mineral and water development practices, such as offshore oil and gas exploration, development and production; construction of inshore pipeline canals and refineries; power plant construction/operation and urban development. This report, and five other southern California reports, covering Carpinteria Marsh (Santa Barbara County), Anaheim Bay-Huntington Harbor (Orange County), Mugu Lagoon (Ventura County), the Northern Santa Barbara County Coastal
Wetlands, and the Nipomo Dunes and Wetlands (San Luis Obispo County), are scheduled to be part of the Department's "Coastal Wetland Series" (see inside front cover). (154 pp.
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