3,358 research outputs found
Evaluating the Dynamic Nature of Market Risk
This study examines the systematic risk present in major crops for the United States and three corn-belt states. An index of commodities is used in conjunction with cash receipts to generate dynamic estimates of the systematic risk for each crop and state. In our study, we find that beta estimates from a time varying parameter model (FLS) and OLS formulation are substantially different. From our graphs of betas over time, one gains insight into the changing nature of risk and the impact of institutional and macroeconomic events. Systematic risk is shown to increase for most crops over the analyzed period with significant changes in volatility after the collapse of the Bretton Woods Accord.Systematic risk, flexible least squares, single index model, farm policy, macroeconomics, Agribusiness, Agricultural Finance, Consumer/Household Economics, Demand and Price Analysis, Farm Management, Financial Economics, Institutional and Behavioral Economics, Marketing, Risk and Uncertainty,
Performance of a Brief Assessment Tool for Identifying Substance Use Disorders
Objective: Evaluation of the performance of a brief assessment tool for identifying substance use disorders. The Triage Assessment for Addictive Disorders (TAAD) is a triage instrument that provides professionals with a tool to evaluate indications of current substance use disorders in accordance with the DSM-IV diagnostic criteria. The TAAD is a 31-item structured interview that addresses both alcohol and other drug issues to discriminate among those with no clear indications of a diagnosis, those with definite, current indications of abuse or dependence, and those with inconclusive diagnostic indications.
Methods: Employing a sample of 1325 women between the ages of 18 and 60, reliability estimates and problem profiles produced by the TAAD were evaluated.
Results: The Cronbach alpha coefficients for internal consistency for both the alcohol and drug dependence scales were .92. The alpha coefficients for the alcohol and drug abuse scales were .83 and .84 respectively. The diagnostic profiles elicited from the TAAD indicate that alcohol and drug dependences are the more definitive and distinct syndromes compared with the abuse syndromes.
Conclusions: The diagnostic profiles from this sample are consistent with previous research. The Cronbach alpha coefficients suggest that the TAAD provides an internally consistent index for alcohol and drug dependence and abuse. Implications for use in clinical practice and the need for further research regarding the psychometric properties of the TAAD are discussed
The Probability of Winning at Solitaire: A Preliminary Description of a State-Transition Approach
This paper is the very beginning of a proposal of an approach that may offer a method for solving a currently unsolved problem - calculating the probability of winning at Solitaire. We describe the game as a series of state transitions, from an initial state to a winning state. The state variables and allowable transitions are described, and a list of ânext stepsâ is given. It is hoped that this approach may prove fruitful
Scientific Visualization Using the Flow Analysis Software Toolkit (FAST)
Over the past few years the Flow Analysis Software Toolkit (FAST) has matured into a useful tool for visualizing and analyzing scientific data on high-performance graphics workstations. Originally designed for visualizing the results of fluid dynamics research, FAST has demonstrated its flexibility by being used in several other areas of scientific research. These research areas include earth and space sciences, acid rain and ozone modelling, and automotive design, just to name a few. This paper describes the current status of FAST, including the basic concepts, architecture, existing functionality and features, and some of the known applications for which FAST is being used. A few of the applications, by both NASA and non-NASA agencies, are outlined in more detail. Described in the Outlines are the goals of each visualization project, the techniques or 'tricks' used lo produce the desired results, and custom modifications to FAST, if any, done to further enhance the analysis. Some of the future directions for FAST are also described
Ongoing Formation of Bulges and Black Holes in the Local Universe: New Insights from GALEX
We analyze a volume-limited sample of massive bulge-dominated galaxies with
data from both the Sloan Digital Sky Survey and the Galaxy Evolution Explorer
(GALEX) satellite. The galaxies have central velocity dispersions greater than
100 km/s and stellar surface mass densities that lie above the value where
galaxies transition from actively star forming to passive systems. The sample
is limited to redshifts 0.03<z<0.07. At these distances, the SDSS spectra
sample the light from the bulge-dominated central regions of the galaxies. The
GALEX NUV data provide high sensitivity to low rates of global star formation
in these systems. Our sample of bulge-dominated galaxies exhibits a much larger
dispersion in NUV-r colour than in optical g-r colour. Nearly all of the
galaxies with bluer NUV-r colours are AGN. Both GALEX images and SDSS colour
profiles demonstrate that the excess UV light is associated with an extended
disk. We find that galaxies with red outer regions almost never have a young
bulge or a strong AGN. Galaxies with blue outer regions have bulges and black
holes that span a wide range in age and accretion rate. Galaxies with young
bulges and strongly accreting black holes almost always have blue outer disks.
Our suggested scenario is one in which the source of gas that builds the bulge
and black hole is a low mass reservoir of cold gas in the disk.The presence of
this gas is a necessary, but not sufficient condition for bulge and black hole
growth. Some mechanism must transport this gas inwards in a time variable way.
As the gas in the disk is converted into stars, the galaxies will turn red, but
further gas infall can bring them back into the blue NUV-r sequence.(Abridged)Comment: 34 pages, 16 figures. Accepted for the GALEX special issue of ApJ
The UV-Optical Galaxy Color-Magnitude Diagram. I. Basic Properties
We have analyzed the bivariate distribution of galaxies as a function of ultraviolet-optical colors and absolute magnitudes in the local universe. The sample consists of galaxies with redshifts and optical photometry from the Sloan Digital Sky Survey (SDSS) main galaxy sample matched with detections in the near-ultraviolet (NUV) and far-ultraviolet (FUV) bands in the Medium Imaging Survey being carried out by the Galaxy Evolution Explorer (GALEX) satellite. In the (NUV â r)_(0.1) versus M_(r,0.1) galaxy color-magnitude diagram, the galaxies separate into two well-defined blue and red sequences. The (NUV â r)_(0.1) color distribution at each M_(r,0.1) is not well fit by the sum of two Gaussians due to an excess of galaxies in between the two sequences. The peaks of both sequences become redder with increasing luminosity, with a distinct blue peak visible up to M_(r,0.1) ~ â 23. The r_(0.1)-band luminosity functions vary systematically with color, with the faint-end slope and characteristic luminosity gradually increasing with color. After correcting for attenuation due to dust, we find that approximately one-quarter of the color variation along the blue sequence is due to dust, with the remainder due to star formation history and metallicity. Finally, we present the distribution of galaxies as a function of specific star formation rate and stellar mass. The specific star formation rates imply that galaxies along the blue sequence progress from low-mass galaxies with star formation rates that increase somewhat with time to more massive galaxies with a more or less constant star formation rate. Above a stellar mass of ~10^(10.5) M_â, galaxies with low ratios of current to past averaged star formation rate begin to dominate
The Calibration and Data Products of the Galaxy Evolution Explorer
We describe the calibration status and data products pertaining to the GR2
and GR3 data releases of the Galaxy Evolution Explorer (GALEX). These releases
have identical pipeline calibrations that are significantly improved over the
GR1 data release. GALEX continues to survey the sky in the Far Ultraviolet
(FUV, ~154 nm) and Near Ultraviolet (NUV, ~232 nm) bands, providing
simultaneous imaging with a pair of photon counting, microchannel plate, delay
line readout detectors. These 1.25 degree field-of-view detectors are
well-suited to ultraviolet observations because of their excellent red
rejection and negligible background. A dithered mode of observing and photon
list output pose complex requirements on the data processing pipeline,
entangling detector calibrations and aspect reconstruction algorithms. Recent
improvements have achieved photometric repeatability of 0.05 and 0.03 mAB in
the FUV and NUV, respectively. We have detected a long term drift of order 1%
FUV and 6% NUV over the mission. Astrometric precision is of order 0.5" RMS in
both bands. In this paper we provide the GALEX user with a broad overview of
the calibration issues likely to be confronted in the current release.
Improvements are likely as the GALEX mission continues into an extended phase
with a healthy instrument, no consumables, and increased opportunities for
guest investigations.Comment: Accepted to the ApJS (a special GALEX issue
How U.S. Ocean Policy and Market Power Can Reform the Coral Reef Wildlife Trade
As the worldâs largest importer of marine ornamental species for the aquaria, curio, home dĂ©cor, and jewelry industries, the United States has an opportunity to leverage its considerable market power to promote more sustainable trade and reduce the effects of ornamental trade stress on coral reefs worldwide. Evidence indicates that collection of some coral reef animals for these trades has caused virtual elimination of local populations, major changes in age structure, and promotion of collection practices that destroy reef habitats. Management and enforcement of collection activities in major source countries such as Indonesia and the Philippines remain weak. Strengthening US trade laws and enforcement capabilities combined with increasing consumer and industry demand for responsible conservation can create strong incentives for improving management in source countries. This is particularly important in light of the March 2010 failure of the parties to the Convention on International Trade in Endangered Species (CITES) to take action on key groups of corals
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