Why Intelligent People Live Longer

Numerous studies find a positive relationship between cognitive ability, IQ as measured in childhood or youth, and subsequent survival. Explanations range from the idea that low ability is an indicator of adverse systemic events in early life to the idea that high cognitive functioning is required continuously to maintain health and reduce threats to survival. The Wisconsin Longitudinal Study (WLS) has followed a large cohort of Wisconsin high school seniors from ages 18 to 69. As expected, in the WLS survival varies positively with adolescent IQ. However, rank in high school class accounts completely for the relationship between IQ and survival, and it has a much larger effect on survival. These findings suggest that cognitive functioning improves survival by promoting behaviours that boost health status, minimize exposure to known risks and optimize returns to health producing inputs, and that such behaviours are firmly in place by late adolescence

Atomic discreteness and the nature of structural equilibrium in conductance histograms of electromigrated Cu-nanocontacts

We investigate the histograms of conductance values obtained during controlled electromigration thinning of Cu thin films. We focus on the question whether the most frequently observed conductance values, apparent as peaks in conductance histograms, can be attributed to the atomic structure of the wire. To this end we calculate the Fourier transform of the conductance histograms. We find all the frequencies matching the highly symmetric crystallographic directions of fcc-Cu. In addition, there are other frequencies explainable by oxidation and possibly formation of hcp-Cu. With these structures we can explain all peaks occurring in the Fourier transform within the relevant range. The results remain the same if only a third of the samples are included. By comparing our results to the ones available in the literature on work-hardened nanowires we find indications that even at low temperatures of the environment, metallic nanocontacts could show enhanced electromigration at low current densities due to defects enhancing electron scattering

Crop Yield and Price Distributional Effects on Revenue Hedging

The use of crop yield futures contracts is examined. The expectation being modeled here reflects that of an Illinois corn and soybeans producer at planting, of revenue realized at harvest. The effects of using price and crop yield contracts are measured by comparing the results of the expected distribution to the expected distribution found under five general alternatives: 1) a revenue hedge using just price futures, 2) a revenue hedge using crop yield futures, 3) an unhedged scenario where revenue is determined by realized prices and yields, 4) an unhedged scenario where revenue is determined by realized prices and yields and by participation in government support programs with deficiency payments, and 5) a no hedge scenario where revenue is determined by realized prices and yields and by participation in a proposed revenue-assurance program. We draw four major conclusions from the results. First, hedging effectiveness using the new crop yield contract depends critically on yield basis risk which presumably can be reduced considerably by covering large geographical areas. Second, crop yield futures can be used in conjunction with price futures to derive risk management benefits significantly higher than using either of the two alone. Third, hedging using price and crop yield futures has a potential to offer benefits larger than those from the simulated revenue assurance program. However, the robustness of the findings depends largely on whether yield basis risk varies significantly across regions. Finally, the qualitative results described by the above three conclusions do not change depending on whether yields are distributed according to the beta or lognormal distribution.published or submitted for publicationnot peer reviewe

THE USE OF MEAN-VARIANCE FOR COMMODITY FUTURES AND OPTIONS HEDGING DECISIONS

This study provides additional evidence of the usefulness of mean-variance procedures in the presence of options which can truncate and skew the returns distribution. Using a simulation analysis, price hedging decisions are examined for hog producers when options are available. Mean-variance results are contrasted with optimal decisions based on negative exponential and Cox-Rubinstein utility functions over 56 ending price scenarios and two levels of risk aversion. The findings from our simulation, which considers discrete contracts, basis risk, lognormality in prices, transactions costs, and alternative utility specifications, affirm the usefulness of mean-variance framework.Marketing,

CROP YIELD AND PRICE DISTRIBUTIONAL EFFECTS ON REVENUE HEDGING

The use of crop yield futures contracts is examined. The expectation being modeled here reflects that of an Illinois corn and soybeans producer at planting, of revenue realized at harvest. The effects of using price and crop yield contracts are measured by comparing the results of the expected distribution to the expected distribution found under five general alternatives: 1) a revenue hedge using just price futures, 2) a revenue hedge using crop yield futures, 3) an unhedged scenario where revenue is determined by realized prices and yields, 4) an unhedged scenario where revenue is determined by realized prices and yields and by participation in government support programs with deficiency payments, and 5) a no hedge scenario where revenue is determined by realized prices and yields and by participation in a proposed revenue-assurance program. We draw four major conclusions from the results. First, hedging effectiveness using the new crop yield contract depends critically on yield basis risk which presumably can be reduced considerably by covering large geographical areas. Second, crop yield futures can be used in conjunction with price futures to derive risk management benefits significantly higher than using either of the two alone. Third, hedging using price and crop yield futures has a potential to offer benefits larger than those from the simulated revenue assurance program. However, the robustness of the findings depends largely on whether yield basis risk varies significantly across regions. Finally, the qualitative results described by the above three conclusions do not change depending on whether yields are distributed according to the beta or lognormal distribution.Marketing,

Projected 1985 impacts of alternative inland waterway user fees on corn, soybean, and wheat transport

The Inland Waterway Revenue Act of 1978 (Public Law 95-502) established a barge-fuel tax of four cents per gallon that became effective in October of 1980. The tax rate will increase to ten cents per gallon by 1985. The tax revenue is used to recover part of the cost of governmental provision of a navigable river system;This study examines the effects of various taxing methods at rates that are estimated to recover all of the costs of providing an inland waterway system for commercial navigation. Impacts of the alternative waterway user fees on transport modal shares and revenues, relationships between origins and destinations, tax revenue generation, and transport costs of corn, wheat, and soybean haulage in 1985 are projected;A linear programming model that specifies alternative transport mode, crop, origin, destination, and time period combinations is developed. A model solution is that combination which minimizes the total annual cost of transporting and handling grain from U.S. grain-surplus regions to domestic and foreign grain-deficit regions. Six solutions are found under six different user fee scenarios. No user fees exist in one scenario. A fuel tax, ton-mile tax, and a combination of fuel and ton-mile tax are used as three alternative scenarios of user fee imposition. Rail rate increases, in response to a ton-mile tax, are incorporated in the last two scenarios;The solution results indicate that up to 255 million bushels of corn, wheat, and soybeans will be diverted from barge transport to rail and truck after user fees are imposed. Most of this diversion is Iowa- and Minnesota-produced grain. Each crop has around 15 percent of its respective barge traffic diverted when taxes are imposed. Total user fees collected on grain shipments range from 50 million to 61.2 million and, based on the grain that moves by barge after tax imposition, the tax revenues represent a per bushel average that ranges from 2.65 to 3.27 cents

The Growing Mismatch Between Patient Longevity and the Service Life of Implantable Cardioverter-Defibrillators

Implantable cardioverter-defibrillators (ICDs) are lifesaving devices. Over 100,000 patients received ICDs in 2004 at a cost of $2 billion for the pulse generators alone. Because of expanded indications and coverage by Medicare, the number of ICD implantations and replacements is expected to increase dramatically during the next decade. The average ICD patient at our institution now lives nearly 10 years after the procedure. However, the service life of pulse generators has decreased from 4.7 ± 1 year for single-chamber units to 4.0 ± 1 year for dual-chamber devices. This mismatch between patient longevity and the service life of ICDs poses a significant clinical and economic burden that must be addressed. One near-term solution is for manufacturers to provide devices with larger batteries so that most patients can have an ICD pulse generator that lasts a lifetime. For the long-term, more robust or renewable energy sources are needed

Assessing Policy Changes on the Cost of Husbanding Services for Navy Ships

Excerpt from the Proceedings of the Nineteenth Annual Acquisition Research SymposiumIn the wake of a major corruption conspiracy, the U.S. Navy reformed husbanding services procedures to increase competition, auditability, and accountability with the end goal of reducing expenditures. The first policy change, Off-Ship Bill Pay (OSBP), formalized a process for procuring, rendering, and paying for husbanding services to increase oversight. The second policy change increased the use of multiple award contracts (MACs) in which multiple vendors are awarded a contract over a region, increasing competition for individual port visits. The purpose of this paper is to analyze the effects of these policy changes on the cost of husbanding services. Multiple regression was used to account for port visit characteristics that affect cost such as ship type and the number of days in port. MACs demonstrated a reduction effect on the cost of port visits. Further, OSBP appears to have a negligible effect on port visit cost after the initial learning curve for both Navy personnel and vendors.Approved for public release; distribution is unlimited

Assessing Policy Changes on the Cost of Husbanding Services for Navy Ships

Excerpt from the Proceedings of the Nineteenth Annual Acquisition Research SymposiumIn the wake of a major corruption conspiracy, the U.S. Navy reformed husbanding services procedures to increase competition, auditability, and accountability with the end goal of reducing expenditures. The first policy change, Off-Ship Bill Pay (OSBP), formalized a process for procuring, rendering, and paying for husbanding services to increase oversight. The second policy change increased the use of multiple award contracts (MACs) in which multiple vendors are awarded a contract over a region, increasing competition for individual port visits. The purpose of this paper is to analyze the effects of these policy changes on the cost of husbanding services. Multiple regression was used to account for port visit characteristics that affect cost such as ship type and the number of days in port. MACs demonstrated a reduction effect on the cost of port visits. Further, OSBP appears to have a negligible effect on port visit cost after the initial learning curve for both Navy personnel and vendors.Approved for public release; distribution is unlimited