43,291 research outputs found
ECONOMETRIC INVESTIGATION OF THE DYNAMIC EFFECTS OF THE 1983 PAYMENT-IN-KIND PROGRAM ON THE WHEAT ECONOMY
A stochastic, dynamic, and control-system econometric model of the wheat sector is developed to assess the effects of the Payment-in Kind program. Empirical results the complex dynamics of the responses. Reduced storage costs and deficiency payments for the U.S. government and increased income for wheat farmers are benefits from the PIK program in the short-run. Increased direct government transfers from the public to support the program were required. The long-run economic implications are not clearly desirable. This is due primarily to the highly sensitive international wheat market.Agricultural and Food Policy, Crop Production/Industries,
Investigating Multiple Solutions in the Constrained Minimal Supersymmetric Standard Model
Recent work has shown that the Constrained Minimal Supersymmetric Standard
Model (CMSSM) can possess several distinct solutions for certain values of its
parameters. The extra solutions were not previously found by public
supersymmetric spectrum generators because fixed point iteration (the algorithm
used by the generators) is unstable in the neighbourhood of these solutions.
The existence of the additional solutions calls into question the robustness of
exclusion limits derived from collider experiments and cosmological
observations upon the CMSSM, because limits were only placed on one of the
solutions. Here, we map the CMSSM by exploring its multi-dimensional parameter
space using the shooting method, which is not subject to the stability issues
which can plague fixed point iteration. We are able to find multiple solutions
where in all previous literature only one was found. The multiple solutions are
of two distinct classes. One class, close to the border of bad electroweak
symmetry breaking, is disfavoured by LEP2 searches for neutralinos and
charginos. The other class has sparticles that are heavy enough to evade the
LEP2 bounds. Chargino masses may differ by up to around 10% between the
different solutions, whereas other sparticle masses differ at the sub-percent
level. The prediction for the dark matter relic density can vary by a hundred
percent or more between the different solutions, so analyses employing the dark
matter constraint are incomplete without their inclusion.Comment: 30 pages, 12 figures, 2 tables; v2: added discussion on speed of
shooting method, fixed typos, matches published versio
PC programs for the prediction of the linear stability behavior of liquid propellant propulsion systems and application to current MSFC rocket engine test programs, volume 1
Research on propulsion stability (chugging and acoustic modes), and propellant valve control was investigated. As part of the activation of the new liquid propulsion test facilities, it is necessary to analyze total propulsion system stability. To accomplish this, several codes were built to run on desktop 386 machines. These codes enable one to analyze the stability question associated with the propellant feed systems. In addition, further work was adapted to this computing environment and furnished along with other codes. This latter inclusion furnishes those interested in high frequency oscillatory combustion behavior (that does not couple to the feed system) a set of codes for study of proposed liquid rocket engines
Checklist of the Ants of Michigan (Hymenoptera: Formicidae)
A total of 113 species of ants is recorded by county from the state of Michigan. The list is based upon literature records and specimens in the authors\u27 collections and those of the University of Michigan Museum of Zoology and the Michigan State University Department of Entomology. The list includes 3 species in Ponerinae, 44 in Myrnucinae, 6 in Dolichoderinae, and 60 in Formicinae. Ten species represent new state records. Five distribution pat- terns are evident: statewide (39 species), southern counties only (5), southern 3/4th of Lower Peninsula (10), Lower Peninsula (17), and Upper Peninsula (2). Forty species have been collected too infrequently to determine the distribution within the state
Low-frequency absorption cross section of the electromagnetic waves for the extreme Reissner-Nordstrom black holes in higher dimensions
We investigate the low-frequency absorption cross section of the
electromagnetic waves for the extreme Reissner-Nordstrom black holes in higher
dimensions. We first construct the exact solutions to the relevant wave
equations in the zero-frequency limit. In most cases it is possible to use
these solutions to find the transmission coefficients of partial waves in the
low-frequency limit. We use these transmission coefficients to calculate the
low-frequency absorption cross section in five and six spacetime dimensions. We
find that this cross section is dominated by the modes with l=2 in the
spherical-harmonic expansion rather than those with l=1, as might have been
expected, because of the mixing between the electromagnetic and gravitational
waves. We also find an upper limit for the low-frequency absorption cross
section in dimensions higher than six.Comment: 7 pages, 1 figure, Phys. Rev. D (to appear
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