GROWTH AND SURVIVAL IN WHEAT FARMING: THE IMPACT OF LAND EXPANSION AND BORROWING RESTRAINTS

Simulation is used to examine impacts of land expansion strategies and self-imposed borrowing limits upon growth and survival odds of a dryland wheat farm over a 15-year period. Compared to share-rent expansion, purchasing land shows only marginally great growth at best, with substantially higher odds of firm failure. A tradeoff of enhanced survival at the expense of reduced growth results from more conservative borrowing for land. The marginal value of liquidity (for assisting survival) is relatively high at lower levels of credit reserves.Agricultural Finance, Crop Production/Industries, Land Economics/Use,

COMPARISON OF LIVESTOCK PRICE FORECASTING USING SIMPLE TECHNIQUES, FORWARD PRICING AND OUTLOOK INFORMATION

Demand and Price Analysis,

The influence of temperature dynamics and dynamic finite ion Larmor radius effects on seeded high amplitude plasma blobs

Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic finite Larmor radius effects. We find that the maximal radial blob velocity increases with the square root of the initial pressure perturbation and that a finite Larmor radius contributes to highly compact blob structures that propagate in the poloidal direction. An extensive parameter study reveals that a smooth transition to this compact blob regime occurs when the finite Larmor radius effect strength, defined by the ratio of the magnetic field aligned component of the ion diamagnetic to the $\vec{E}\times\vec{B}$ vorticity, exceeds unity. The maximal radial blob velocities agree excellently with the inertial velocity scaling law over more than an order of magnitude. We show that the finite Larmor radius effect strength affects the poloidal and total particle transport and present an empirical scaling law for the poloidal and total blob velocities. Distinctions to the blob behaviour in the isothermal limit with constant finite Larmor radius effects are highlighted

INCORPORATING SAFETY-FIRST CONSTRAINTS IN LINEAR PROGRAMMING PRODUCTION MODELS

A recent survey indicated that many procedures view risk in a safety-first context. Traditional methods used to impose safety-first constraints in optimization models have often been difficult to implement. This is particularly true when endogenous decisions affect the distribution of the chance-constrained random variable. This paper presents a method whereby probabilistic constraints can be easily imposed upon finitely discrete random variables. The procedure uses a linear version of the lower partial moment stochastic inequality. The resulting solutions are somewhat conservative but are less so than the results using the previously published mean income-absolute deviation stochastic inequality.Production Economics, Research Methods/ Statistical Methods,

PERFORMANCE OF RISK-INCOME MODELS OUTSIDE THE ORIGINAL DATA SET

Selected risk programming solutions (i.e., profit maximization, Target-MOTAD, and MOTAD) are tested in an economic environment outside the data set from which they were developed. Specifically, solutions are derived from either a longer 10-year (1965-74) or shorter 6-year estimation period (1969-74), and then, they are tested for consistent risk-income characteristics over a later 10-year period (1975-84). Risk solutions estimated from earlier periods perform well in the later test period in spite of different economic conditions between time periods. However, favorable performance may be related to the specific example used in this analysis. Further testing for other farm situations is needed before general conclusions can be reached.Risk and Uncertainty,

A Case Study of Fall versus Spring Calving for the Rocky Mountain West

Feeder cattle prices are generally lower in the fall, when the volume of calves for sale is highest. Most ranches in the Rocky Mountains calve in March or April, which results in the sale of weaned calves in October, when feeder cattle prices tend to be lowest. This study was initiated with the idea that a rancher might improve profitability by switching to fall calving, which would enable them to sell calves in April at a higher price. In this study, fall calving generated both higher and less variable profit, but mainly because of cost savings.Livestock Production/Industries,

Imaging radar polarimetry from wave synthesis

It was shown that it is possible to measure the complete scattering matrix of an object using data acquired on a single aircraft pass, and can combine the signals later in the data processor to generate radar images corresponding to any desired combination of transmit and receive polarization. Various scattering models predict different dependence on polarization state of received power from an object. The imaging polarimeter permits determination of this dependence, which is called the polarization signature, of each point in a radar image. Comparison of the theoretical predictions and observational data yield identification of possible scattering mechanisms for each area of interest. It was found that backscatter from the ocean is highly polarized and well-modeled by Bragg scattering, while scattering from trees in a city park possesses a considerable unpolarized component. Urban regions exhibit the characteristics expected from dihedral corner reflectors and their polarization signatures are quite different from the one-bounce Bragg model

Absence of orbital-selective Mott transition in Ca_2-xSr_xRuO4

Quasi-particle spectra of the layer perovskite Sr$_2$RuO$_4$ are calculated within Dynamical Mean Field Theory for increasing values of the on-site Coulomb energy $U$. At small $U$ the planar geometry splits the $t_{2g}$ bands near $E_F$ into a wide, two-dimensional $d_{xy}$ band and two narrow, nearly one-dimensional $d_{xz,yz}$ bands. At larger $U$, however, the spectral distribution of these states exhibit similar correlation features, suggesting a common metal-insulator transition for all $t_{2g}$ bands at the same critical $U$.Comment: 4 pages, 4 figure