INVESTIGATING PREFERENCE HETEROGENEITY IN A REPEATED DISCRETE-CHOICE RECREATION DEMAND MODEL OF ATLANTIC SALMON FISHING

Estimating a demand system under the assumption that preferences are homogeneous may lead to biased estimates of parameters for any specific individual and significantly different expected consumer surplus estimates. This paper investigates several different parametric methods to incorporate heterogeneity in the context of a repeated discrete-choice model. The first is the classic method of assuming utility to be a function of individual characteristics. Second, a random parameters method is proposed, where preference parameters have some known distribution. Random parameters logit causes the random components to be correlated across choice occasions and, in a sense, eliminates IIA. Simulation noise is discussed. Finally, methods are proposed to relax the assumption that the unobserved stochastic component of utility is identically distributed across individuals. For example, randomization of the logit scale, which is a new method, allows noise levels to vary across individuals without the added burden of explaining the source using covariates. The application is to Atlantic salmon fishing, and expected compensating variations and changes in trip patterns are compared across the models for three policy-relevant changes in fishing conditions at the Penobscot River, the best salmon fishing site in Maine.Resource /Energy Economics and Policy,

A Corn Stover Supply Logistics System

Published in Applied Engineering in Agriculture, Vol. 26(3): 455‐461, 2010. American Society of Agricultural and Biological EngineersCorn stover, Economics, GHG emission, Logistics, Roll press compaction, Tub grinding, Agribusiness, Crop Production/Industries,

An assessment and validation study of nuclear reactors for low power space applications

The feasibility and safety of six conceptual small, low power nuclear reactor designs was evaluated. Feasibility evaluations included the determination of sufficient reactivity margins for seven years of full power operation and safe shutdown as well as handling during pre-launch assembly phases. Safety evaluations were concerned with the potential for maintaining subcritical conditions in the event of launch or transportation accidents. These included water immersion accident scenarios both with and without water flooding the core. Results show that most of the concepts can potentially meet the feasibility and safety requirements; however, due to the preliminary nature of the designs considered, more detailed designs will be necessary to enable these concepts to fully meet the safety requirements

The temporal response of bone to unloading

Rats were suspended by their tails with the forelimbs bearing the weight load to simulate the weightlessness of space flight. Growth in bone mass ceased by 1 week in the hindlimbs and lumbar vertebrae in growing rats, while growth in the forelimbs and cervical vertebrae remained unaffected. The effects of selective skeletal unloading on bone formation during 2 weeks of suspension was investigated using radio iostope incorporation (with Ca-45 and H-3 proline) and histomorphometry (with tetracycline labeling). The results of these studies were confirmed by histomorphometric measurements of bone formation using triple tetracycline labeling. This model of simulated weightlessness results in an initial inhibition of bone formation in the unloaded bones. This temporary cessation of bone formation is followed in the accretion of bone mass, which then resumes at a normal rate by 14 days, despite continued skeletal unloading. This cycle of inhibition and resumption of bone formation has profound implication for understanding bone dynamics durng space flight, immobilization, or bed rest and offers an opportunity to study the hormonal and mechanical factors that regulate bone formation

BIOMASS FOR ELECTRICITY AND PROCESS HEAT AT ETHANOL PLANTS

Published in: Applied Engineering in Agriculture, Vol. 22(5): 723-728Biomass, Process heat, Ethanol production, Electricity, Combined heat and power, Resource /Energy Economics and Policy,

INTEGRATING BIOMASS TO PRODUCE HEAT AND POWER AT ETHANOL PLANTS

Published in: Applied Engineering in Agriculture, Vol. 25(2): 227‐244Biomass, Renewable, Sustainable, Model, Gasification, Combustion, Emissions, Ethanol production, Combined heat and power, Resource /Energy Economics and Policy,

ECONOMICS OF BIOMASS GASIFICATION/COMBUSTION AT FUEL ETHANOL PLANTS

Published in Applied Engineering in Agriculture, Vol. 25(3): 391‐400Ethanol, Biomass, Economics, CHP, Emissions, Process heat, Electricity production, Resource /Energy Economics and Policy,

Indian Meal Moth Survivability in Stored Corn With Different Levels of Broken Kernels

Survivability of Indian meal moth, Plodia interpunctella (Hübner) (Lepi-doptera: Pyralidae), larvae fed a standard laboratory diet and whole corn with 0, 5 to 7, and 100% broken corn kernels, was assessed under laboratory conditions at 28o C, 65% relative humidity, and 14:10 h (L:D) photoperiod. A conventional yellow dent corn hybrid (about 3.9% oil content, dry basis) and a high-oil corn hybrid (about 7.7% oil content, dry basis) were tested. Survivability was measured as the percentage of pre-pupae, pupae, and adults observed at the end of the rearing period. For the standard laboratory diet, a mean of 97.5% larvae survived. Percentage of larval survival increased as the percentage of broken corn increased. Mean percentages of larval survival for the conventional yellow dent corn were 6.7, 63.8, and 80.0 for 0, 7, and 100% broken kernels, respectively. The mean percentages of larval survival for the high-oil corn hybrid were 28.3, 81.3, and 100.0 for 0, 5, and 100% broken kernels, respectively. Larval growth rate for high-oil corn was faster than for conventional corn. Results indicate that cleaning corn before storage could reduce P. interpunctella problems