Renormalization Group Analysis of a Gursey Model Inspired Field Theory II

Recently a model, which is equivalent to the scalar form of Gursey model, is shown to be a nontrivial field theoretical model when it is gauged with a SU(N) field. In this paper we study another model that is equivalent to the vector form of the Gursey model. We get a trivial theory when it is coupled with a scalar field. This result changes drastically when it is coupled with an additional SU(N) field. We find a nontrivial field theoretical model under certain conditions.Comment: 10 pages, 10 figures, revtex4, typos corrected, published versio

Do CAPM results hold in a dynamic economy. A Numerical analysis

Cataloged from PDF version of article.In this research we use the projection method (reported by Judd) to find numerical solutions to the Euler equations of a stochastic dynamic growth model. The mode1 that we solve is Brock’s asset pricing model for a variety of parameterizations of the production functions. Using simulated data from the model, conjectures (which are not analytically tractable) can be verified. We show that the market portfolio is mean-variance efficient in this dynamic context. We also show a result that is not available from the static CAPM theory: the efficient frontier shifts up and down over the business cycle

The Equity Premium in Brock's Asset Pricing Model

Cataloged from PDF version of article.In this paper we combine dynamic programming methods with projection methods for solving stochastic growth models. As an application of these methods, we solve Brock’s asset pricing model with a variety of parameterizations. We focused on finding parameterizations that result in an equity premium that is high relative to the variation in consumption. We show (both analytically and numerically) that the equity premium can be higher in a production based asset pricing model than it is in the consumption based asset pricing model, even when the real output level is the same in both models. r 2006 Elsevier B.V. All rights reserved

Stability Evaluation of Simulated Plant and Animal Composts Utilizing Respiration Rates and VOC Emissions

Composting livestock carcasses is an economically and biologically safe method to convert carcasses into odorless, humus like material useful as a soil amendment. One of the key factors to determine the quality of the end product is stability. In this study, mortality composting is simulated using a laboratory set-up operating under aerobic and anaerobic conditions. 85 µm Carboxen/PDMS SPME fiber coating and 10 minutes sampling time are used to sample headspace of decaying plant (corn silage) and animal (shredded whole pig body) tissues. Compounds are separated and identified on a multidimensional gas chromatography-mass spectrometry-olfactometry (MDGC-MS-O) system. Sulfur containing compounds (methyl mercaptan, carbondisulfide, dimethyl disulfide, dimethyl trisulfide, 1,4-dimethyl tetra sulfide) and 1-H-indole and 3-methyl-1H-indole are found as indicators of decaying animal tissue. Peak area counts of these compounds show a decrease after eight week composting time. This trend in VOC emissions can be explained by decrease in the microbial activity and stabilization of the composts. These results are also supported with respirometric measurements. The measured respiration rates of aerobically composted animal tissues during 60 days are half of the respiration rates of fresh animal tissues. Also, a significant difference is observed in VOC emissions from plant and animal materials composted under aerobic and anaerobic conditions. The number of detected compounds during anaerobic decomposition is twice as much as the ones detected under aerobic decomposition. It can be concluded that monitoring VOC emissions can be a useful tool to estimate aeration status and completion of real life mortality composts

Air Sampling and Analysis Method for Volatile Organic Compounds (VOCs) Related to Field-Scale Mortality Composting Operations

In biosecure composting, animal mortalities are so completely isolated during the degradation process that visual inspection cannot be used to monitor progress or the process status. One novel approach is to monitor the volatile organic compounds (VOCs) released by decaying mortalities and to use them as biomarkers of the process status. A new method was developed to quantitatively analyze potential biomarkers—dimethyl disulfide, dimethyl trisulfide, pyrimidine, acetic acid, propanoic acid, 3-methylbutanoic acid, pentanoic acid, and hexanoic acid—from field-scale biosecure mortality composting units. This method was based on collection of air samples from the inside of biosecure composting units using portable pumps and solid phase microextraction (SPME). Among four SPME fiber coatings, 85 μm CAR/PDMS was shown to extract the greatest amount of target analytes during a 1 h sampling time. The calibration curves had high correlation coefficients, ranging from 96 to 99%. Differences between the theoretical concentrations and those estimated from the calibration curves ranged from 1.47 to 20.96%. Method detection limits of the biomarkers were between 11 pptv and 572 ppbv. The applicability of the prepared calibration curves was tested for air samples drawn from field-scale swine mortality composting test units. Results show that the prepared calibration curves were applicable to the concentration ranges of potential biomaker compounds in a biosecure animal mortality composting unit

Performance Evaluation of a Passively-Aerated Plastic-Wrapped Composting System Designed for Emergency Disposal of Swine Mortalities

Monitoring of a passively-aerated plastic-wrapped mortality composting system designed for emergency disposal of diseased swine highlighted the importance of the physical characteristics of materials used to envelop the carcasses. Inadequate moisture was a problem when using envelope materials such as ground cornstalks or straw having low density and high air-filled porosity. High O2 concentrations throughout these materials, and significantly higher moisture levels in the top layers than in the materials surrounding the carcasses, suggested significant air movement and transport of carcass moisture away from the carcasses, resulting in carcass desiccation and incomplete decay. Although internal temperatures and moisture levels in test units constructed with corn silage were much more favorable than in those constructed with cornstalks or straw, less carcass decomposition occurred. Settling and compaction, resulting in high bulk density and low air-filled porosity, caused low O2 concentrations that appeared to impair carcass decay in the silage test units