Hydroxyurea-induced synchronisation of bloodstream stage Trypanosoma brucei

Synchronisation of the <i>Trypanosoma brucei</i> cell cycle proved elusive for many years. A recent report demonstrated that synchronisation of procyclic form cells was possible following treatment with hydroxyurea. Here, that work is extended to the disease-relevant, mammalian-infective bloodstream stage trypanosome. Treatment of bloodstream stage Lister 427 <i>T. Brucei</i> cells growing <i>in vitro</i> with 10 μg ml<sup>−1</sup> hydroxyurea for 6 h led to an enrichment of cells in S phase. Following removal of the drug, cells proceeded uniformly through one round of the cell cycle, providing a much needed tool to enrich for specific cell cycle stages, in a manner similar to hydroxyurea treatment of procyclic form <i>T. brucei.</i&gt

Orbiter structural design and verification

The space shuttle development program provided the opportunity to challenge many of the established practices and approaches used in prior manned space flight programs. The most significant accomplishments and resulting precedents which emerged during the structural development of the space shuttle and the space shuttle orbiter are reviewed. Innovations in criteria, design solutions, and certification are highlighted, and brief comments on the lessons learned are included. Thermal stress, graphite epoxy moisture, window structure, and structural inspection are discussed under lessons learned

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

Data for the paper on "Early school failure predicts teenage pregnancy and marriage: a large population-based cohort study in Northern Malawi"

The data originate from a demographic surveillance site (DSS) in Karonga district in northern Malawi covering a population of >35,000 individuals from approx. 8000 households since 2002. This is run by MEIRU (Malawi Epidemiology and Intervention Research Unit). Annual individual and household-level socio-demographic and schooling data were combined with data on participants’ sexual behaviour, including age at sexual debut, pregnancy and marriage to examine the relationship between school progression (drop-out and age-for-grade) and sexual debut, pregnancy and marriage

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,

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,

U.S. Meat Demand: Household Dynamics and Media Information Impacts

This article uses national, quarterly data to examine U.S. meat demand using the Rotterdam model. We investigate the effect of multiple information indices linking different health concerns with diet, changes in household dynamics, and meat recall information. Medical journal articles linking iron, zinc, and protein with health and diet increase beef and poultry demand, whereas articles dealing with fat, cholesterol, and diet concerns reduce beef demand. Increasing consumption of food away from home enhances pork and poultry demand while reducing beef demand. Combined, these results provide a more complete and current understanding of the impact of multiple information factors faced by U.S. consumers.Atkins diet, female workforce, food away from home, food safety, health concerns, meat recalls, U.S. meat demand, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries,

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,