Bubble formation at two adjacent submerged orifices in inviscid fluids

A theoretical model has been developed as an extension of single orifice bubble formation to investigate the growth and detachment of vapor/gas bubbles formed at two adjacent submerged orifices in inviscid fluids. The mathematical model treats the two bubbles as an expanding control volume moving to the line of centers above a wall. The movement of the bubbles is obtained by application of force balance acting on the bubble and accounts for surface tension, buoyancy, steam momentum and liquid inertia effects. The liquid inertia effects are determined by applying inviscid and irrotational flow assumptions to allow potential flow theory to calculate the liquid velocity field which then allows the pressure distribution to be calculated. The model is extended to include the mass and energy equations to model the steam bubble formation in sub-cooled water. The theoretical results are compared with the available experimental data of bubble formation during constant mass flow steam bubble formation at two submerged upward facing orifices in sub-cooled water. The model was validated by available experimental data for the growth and detachment processes of two adjacent 1 mm orifices at system pressures of 2 and 3 bars, flow rates of 1.2-4 g/min at sub-cooling of 3.5-35 ºC. The comparisons of theory and experiments indicate that the model successfully predicts the bubbles growth and detachment for the range of conditions studied

GRID PRICING VERSUS AVERAGE PRICING FOR SLAUGHTER CATTLE: AN EMPIRICAL ANALYSIS

The paper compares weekly producer revenue under grid pricing and average dressed weight pricing methods for 2560 cattle over a period of 102 weeks. Regression analysis is applied to identify factors affecting the revenue differential.Livestock Production/Industries,

NAFTA INTRA INDUSTRY TRADE IN AGRICULTURAL FOOD PRODUCTS

The paper focuses on NAFTA's impact on intra-industry and inter-industry trade in agricultural food products. Bilateral trade among U.S., Canada, and Mexico, as well as their trade with the rest of the world during 1990 and 1995 are investigated. U.S. trade patterns for agricultural food products are slowly changing.International Relations/Trade,

Carcass Quality Volume and Grid Pricing: An Investigation of Cause and Effect

The relationship between publicly reported weekly grid premiums and discounts for specific carcass characteristics and the percentage of those characteristics reflected in total weekly slaughter volume (i.e., proportional slaughter volume) is investigated. Granger Causality and multi-lag VAR models were used to investigate if grid premiums and discounts were efficiently transmitting market signals to producers with respect to carcass quality attributes. The empirical evidence indicates that there is little evidence to suggest that grid prices are providing efficient price signals to buyers and sellers with respect to market valuation of desirable and undesirable beef carcass characteristics.grid pricing, price discovery, price reporting, slaughter cattle

GRID PRICING FOR FED CATTLE: AN EMPIRICAL ANALYSIS

Weekly grid premium and discount price date for fed cattle have been collected over a 3-year period. The grid price data are combined with carcass data (2590 South Dakota slaughter steers) to investigate the variability in the average weekly carcass premium is affected by changes in packer-determined grid premiums and discounts on a weekly basis. The three-stage recursive model is then estimated using an autoregressive procedure. The results of the empirical analysis indicated that among all grid premiums and discounts, it is the choice-select discount that plays the dominant role in determining weekly changes in the average weekly carcass premium (discount).slaughter cattle, grid pricing, average pricing, value-based-marketing, Marketing,

Variance Risk Premiums and Predictive Power of Alternative Forward Variances in the Corn Market

We propose a fear index for corn using the variance swap rate synthesized from out-of-the-money call and put options as a measure of implied variance. Previous studies estimate implied variance based on Black (1976) model or forecast variance using the GARCH models. Our implied variance approach, based on variance swap rate, is model independent. We compute the daily 60-day variance risk premiums based on the difference between the realized variance and implied variance for the period from 1987 to 2009. We find negative and time-varying variance risk premiums in the corn market. Our results contrast with Egelkraut, Garcia, and Sherrick (2007), but are in line with the findings of Simon (2002). We conclude that our synthesized implied variance contains superior information about future realized variance relative to the implied variance estimates based on the Black (1976) model and the variance forecasted using the GARCH(1,1) model.Variance Risk Premium, Variance Swap, Model-free Variance, Implied Variance, Realized Variance, Corn VIX

Public Price Reporting in the Cash Market for Live Cattle: A Spatial Market Approach

Legislative authorization for the Livestock Mandatory Reporting Act of 1999 was renewed in October of 2006. One of the cited justifications for implementing mandatory reporting was that the voluntary reporting system for the slaughter cattle cash market was unable to provide accurate and timely market information. We extend the spatial market analysis literature by developing a methodology for detecting distortions in spatial relationships across related price series. Using spatially linked regional markets, we compare state-level mandatory price-reporting data to the U.S. Department of Agriculture voluntarily reported state data to determine if the spatial relationship between price-reporting mechanisms was disrupted by market distortions prior to implementation of federal mandatory price reporting. We found no empirical evidence of system failure; therefore, we conclude that market thinning or noncompetitive behavior had not reached the level necessary to disrupt the ability of the voluntary price-reporting system to provide timely and accurate price information.public price reporting, spatial markets, market integration, price transparency, price discovery, livestock markets, Livestock Production/Industries, Marketing,

Price Transparency in the Voluntary Price Reporting System for Live Cattle: Theory and Empirical Evidence

Interregional spatial linkages between South Dakota and Nebraska cash markets for slaughter cattle are investigated. Econometric procedures are used to test whether a thinning market effect or strategic price reporting behavior by packers has degraded market transparency under the voluntary price reporting system. Empirical evidence suggests transparency was not degraded.Demand and Price Analysis,

Inhibition of lipolysis: A novel explanation for the hypothermic actions of acetaminophen in non-febrile rodents

Acetaminophen is both widely used to treat children with fever and is also responsible for thousands being hospitalised annually. Historically the antipyretic actions of acetaminophen were attributed to the inhibition of cyclooxygenase (COX-1/2) enzymes and more recently a novel COX-1 variant (COX-3) located in the brain. However, the evidence for acetaminophen-mediated COX inhibition remains contentious. This study assesses the impact of acetaminophen and other putative COX-3 inhibitors on the release of fatty acids during lipolysis as an alternative mechanism by which antipyretics can reduce body temperature during fever. 3T3-L1 adipocytes, primary brown adipocytes and isolated mitochondria were exposed to COX-3 inhibitors and lipolysis and mitochondrial electron transport chain function assessed. Acetaminophen, aminopyrine and antipyrine at 1–10 mM caused a significant decrease (up to 70%; P < 0.01, from control) in lipolysis within 1, 3 and 24 h without affecting cell viability. The inhibition was observed regardless of where along its signalling pathway lipolysis was stimulated. All three compounds were found to significantly attenuate mitochondrial function by up to 30% for complex I and 40% for complex II (P < 0.01, from control). These novel observations combined with the known limited inhibition of the COX enzymes by acetaminophen suggest both the antipyretic and hypothermia induced by acetaminophen and related compounds could be attributed to the direct inhibition of lipolysis and mitochondrial function, rather than cyclooxygenase inhibition centrally. Further these observations could provide new drug targets for reducing fever with the added bonus of fewer individuals being hospitalized by accidental acetaminophen overdose

The Efficacy of the Grid Marketing Channel for Fed Cattle

Beef industry data suggest that carcass yield and quality grades have shown little improvement over the last six years. Trend analysis of grid market share and carcass quality suggests that grid pricing has not made sufficient progress in achieving the goals envisioned for it as a value based marketing system.grid pricing, price discovery, price reporting, slaughter cattle