Evaluation of installed performance of a wing-tip-mounted pusher turboprop on a semispan wing

An exploratory investigation has been conducted at the Langley Research Center to determine the effect of a wing-tip-mounted pusher turboprop on the aerodynamic characteristics of a semispan wing. Tests were conducted on a semispan model with an upswept, untapered wing and an airdriven motor that powered an SR-2 high-speed propeller located on the tip of the wing as a pusher propeller. All tests were conducted at a Mach number of 0.70 over an angle-of-attack range from approximately -2 to 4 deg at a Reynolds number of 3.82 x 10 to the 6th based on the wing reference chord of 13 in. The data indicate that, as a result of locating the propeller behind the wing trailing edge at the wing tip in the crossflow of the wing-tip vortex, it is possible to improve propeller performance and simultaneously reduce the lift-induced drag

CALENDAR VS. WEEKS TO EXPIRATION LIVESTOCK BASIS FORECASTS: WHICH IS BETTER?

The ability to accurately forecast basis is crucial to risk management strategies employed by many agribusiness firms. Previous research has examined how to effectively use basis forecasts and what factors affect basis, but literature focusing on forecasting basis is sparse. This research evaluates the impact of adopting a time-to-expiration approach, as compared to the more common calendar approach, when forecasting feeder cattle, live cattle, and hog basis. Furthermore, the optimal number of past year's basis levels to include in making basis predictions is evaluated in an out-of-sample framework. Absolute basis forecasts errors are generated for all three commodities and evaluated to determine the signifcance of the two issues mentioned above. Results indicate that basis forecasters should consider using three-year historical averages for feeder cattle and four-year historical averages for live cattle and lean hogs when making basis forecasts. Furthermore, the use of a time-to-expiration method of calculating historical average basis results in very little improvement in basis prediction accuracy compared to the calendar approach.livestock prices, basis, hedging, basis forecasts, Livestock Production/Industries, Marketing,

Acoustic calibration and bathymetric processing with a Klein 5410 sidescan sonar

In 2001, NOAA acquired an L-3 Communications Klein 5410 bathymetric sidescan sonar system that simultaneously provided high resolution multibeam acoustic imagery and wide swath bathymetry. The sonar\u27s inability to produce matching bathymetry in overlapping swaths motivated the detailed acoustic and signal processing analyses described in this thesis. Results of this research include specific corrections for phase distortions introduced by the sonar\u27s transmit pulses, receiver electronics, and transducer elements, which are implemented in a newly-developed full vector bathymetric processing algorithm to estimate accurate acoustic arrival angles for each sample of the seafloor echo acquired by the Klein 5410 sonar. Performance of this algorithm was verified during a survey conducted in New York Harbor during October of 2006. The resulting bathymetry matches bathymetry obtained independently over the same survey area with a Reson SeaBat 8125 focused multibeam echo-sounder operating at the same acoustic frequency

LIVESTOCK BASIS FORECASTS: HOW BENEFICIAL IS THE INCLUSION OF CURRENT INFORMATION?

Successful risk management strategies for agribusiness firms are contingent on the ability to accurately forecast basis. There has been substantial research on the actual use of basis forecasts, yet little research has been conducted on actually forecasting basis. This study evaluates the effect incorporating current basis information into a historical-average-based-forecast has on forecasting accuracy when forecasting live cattle and feeder cattle basis. Furthermore, the optimal weight to place on this current information is evaluated in an out-of-sample framework. Root mean squared errors are generated for both commodities and evaluated to determine the significance of these issues. Results suggest that livestock basis forecasters should consider incorporating a proportion of the difference in current basis and the historical average of the current week when making their projections. The optimal amount of current information to include declines as the time interval between the week the forecast is being made and the week being forecasted increases.livestock prices, hedging, basis forecasts, current information, Livestock Production/Industries, Marketing,

Improving Cattle Basis Forecasting

Successful risk management strategies for agribusiness firms based on futures and options contracts are contingent on their ability to accurately forecast basis. This research addresses three primary questions as they relate to basis forecasting accuracy: (a) What is the impact of adopting a time-to-expiration approach, as compared to the more common calendar-date approach? (b) What is the optimal number of years to include in calculations when forecasting livestock basis using historical averages? and (c) What is the effect of incorporating current basis information into a historical-average-based forecast? Results indicate that use of the time-to-expiration approach has little impact on forecast accuracy compared to using a simple calendar approach, but forecast accuracy is improved by incorporating at least a portion of current basis information into basis forecasts.basis, basis forecasts, cattle prices, current information, hedging, Livestock Production/Industries,

Isolation, characterisation and experimental evolution of phage that infect the horse chestnut tree pathogen, Pseudomonas syringae pv. aesculi

Bleeding canker of horse chestnut trees is a bacterial disease, caused by the bacterium Pseudomonas syringae pv. aesculi, estimated to be present in ~ 50% of UK horse chestnut trees. Currently, the disease has no cure and tree removal can be a common method of reducing inoculum and preventing spread. One potential method of control could be achieved using naturally occurring bacteriophages infective to the causative bacterium. Bacteriophages were isolated from symptomatic and asymptomatic horse chestnut trees in three locations in the South East of England. The phages were found to be belonging to both the Myoviridae and Podoviridae families by RAPD PCR and transmission electron microscopy. Experimental coevolution was carried out to understand the dynamics of bacterial resistance and phage infection and to determine whether new infective phage genotypes would emerge. The phages exhibited different coevolution patterns with their bacterial hosts across time. This approach could be used to generate novel phages for use in biocontrol cocktails in an effort to reduce the potential emergence of bacterial resistance

Consumers Valuations and Choice Processes of Food Safety Enhancement Attributes: An International Study of Beef Consumers

Food safety concerns have had dramatic impacts on food and livestock markets in recent years. Here we examine consumer preferences for various beef food safety assurances. In particular, we evaluate the extent to which such preferences are heterogeneous within and across country-of-residence defined groups and examine the distributional nature of these preferences with respect to marginal improvements in food safety. We collected data from over 4,000 U.S., Canada, Japan, and Mexican consumers. Using mixed logit models we find that Japanese and Mexican consumers have WTP preferences that are nonlinear in the level of food safety risk reduction. Conversely, U.S .and Canadian consumers appear to possess linear preferences. These results suggest that optimal food safety investment strategies hinge critically upon consumer perception of actual food safety improvements, the distributional relationship describing the targeted consumer segment's tradeoff function between WTP premiums and risk reduction levels, and the cost structure of these investments.consumer beef preference, food safety, investment decision, mixed logit, willingness-to-pay, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,

The Role of Consumer Risk Perceptions and Attitudes in Cross Cultural Beef Consumption Changes

Beef food safety events have contributed to considerable market volatility, produced varied consumer reactions, created policy debates, sparked heated trade disputes, and generally contributed to beef industry frustrations. Better understanding of the forces causing observed consumer reactions in light of beef food safety events is critical for policy makers and industry participants. We examine whether consumers altered their beef consumption behavior because of their risk aversion and risk perceptions stemming from information about beef food safety in recent years. We use data from a total of 4,000 consumers in the U.S., Canada, Mexico and Japan to estimate a two-stage Probit/double-bounded Tobit modeling framework. Results reveal there are stark differences in risk perceptions and risk aversion regarding beef food safety across consumers in the four countries and that these differences are revealed through different beef consumption behavior. An improved understanding of food safety perceptions and attitudes will enable policy makers and agricultural industries to better anticipate consumers changing consumption behavior, if a food safety event occurs. Consumers from the four countries examined exhibited heterogeneous food safety perceptions and attitudes. Results suggest that food safety management strategies should vary across countries because of identified differences in food safety risk attitudes and risk perceptions.Cross-culture, risk attitude, risk perception, food safety, beef, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries,

Response to Teladorsagia circumcincta infection in Scottish Blackface lambs with divergent phenotypes for nematode resistance

peer-reviewedThe objective of this study was to identify Scottish Blackface lambs that were at the extremes of the spectrum of resistance to gastrointestinal nematodes and characterise their response to an experimental nematode challenge. Lambs (n = 90) were monitored for faecal egg count (FEC) (2 samples from each of 2 independent natural infections). The most resistant (n = 10) and susceptible (n = 10) individuals were selected and challenged with 30,000 Teladorsagia circumcincta larvae (L3) at 9 months of age. Response to infection was monitored by measuring FEC, plasma pepsinogen, serum antibodies against nematode larval antigens and haematology profile, until necropsy at 71 days post infection. Worm burden, worm fecundity and the level of anti-nematode antibodies in abomasal mucosa were determined at necropsy. FEC was consistently higher in susceptible animals (P < 0.05), validating the selection method. Worm fecundity was significantly reduced in resistant animals (P = 0.03). There was also a significant correlation (r = 0.88; P < 0.001) between the number of adult worms and FEC at slaughter. There was no effect of phenotype (resistance/susceptibility) on plasma pepsinogen or on haematology profile. Phenotype had a significant effect on the level of anti-nematode IgA antibodies in serum (P < 0.01), reflecting a higher peak in resistant animals at day 7 post infection. It is concluded that significant variation in the response to gastrointestinal nematode challenge exists within the Scottish Blackface population with resistant animals displaying significantly lower FEC, lower worm fecundity and higher concentration of anti-nematode IgA antibodies in serum.Kathryn McRae was supported by a Teagasc Walsh fellowship and the Allan and Grace Kay Overseas Scholarship