bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of metabolic rate on longevity in the nematode Caenorhabditis elegans*
Authors: Van Voorhies Wayne A. 
Published: March 2003

SummaryMuch of the recent interest in aging research is due to the discovery of genes in a variety of model organisms that appear to modulate aging. A large amount of research has focused on the use of such long‐lived mutants to examine the fundamental causes of aging. While model organisms do offer many advantages for studying aging, it also critical to consider the limitations of these systems. In particular, ectothermic (poikilothermic) organisms can tolerate a much larger metabolic depression than humans. Thus, considering only chronological longevity when assaying for long‐lived mutants provides a limited perspective on the mechanisms by which longevity is increased. In order to provide true insight into the aging process additional physiological processes, such as metabolic rate, must also be assayed. This is especially true in the nematode Caenorhabditis elegans, which can naturally enter into a metabolically reduced state in which it survives many times longer than its usual lifetime. Currently it is seen as controversial if long‐lived C. elegans mutants retain normal metabolic function. Resolving this issue requires accurately measuring the metabolic rate of C. elegans under conditions that minimize environmental stress. Additionally, the relatively small size of C. elegans requires the use of sensitive methodologies when determining metabolic rates. Several studies indicating that long‐lived C. elegans mutants have normal metabolic rates may be flawed due to the use of inappropriate measurement conditions and techniques. Comparisons of metabolic rate between long‐lived and wild‐type C. elegans under more optimized conditions indicate that the extended longevity of at least some long‐lived C. elegans mutants may be due to a reduction in metabolic rate, rather than an alteration of a metabolically independent genetic mechanism specific to aging.
Neural control of aging skeletal muscle
Authors: Delbono Osvaldo 
Published: March 2003

SummaryFunctional and structural decline in the neuromuscular system with aging has been recognized as a cause of impairment in physical performance and loss of independence in the elderly. Alterations in spinal cord motor neurones and at the neuromuscular junction have been identified as evidence of denervation in skeletal muscles from aging mammals, including humans. However, the reciprocal influences of neurones on gene expression in muscle and of muscle on age‐related neurodegeneration are poorly understood, and, as a result, interventions aimed at delaying or preventing degeneration of the neural component in aging muscle have been largely unsuccessful. The present article discusses the evidence for neural influence on age‐related impairments of skeletal muscle, including a role in excitation–contraction uncoupling. The role of nerves in regulating the trophic actions of insulin‐like growth factor‐1 (IGF‐1) and other neurotrophic factors is considered as a novel influence on the effects of aging on the neuromuscular junction. A better understanding of nerve–muscle interactions will allow for more rational interventions in the aging neuromuscular system.
Are gonadal steroid hormones involved in disorders of brain aging?
Authors: Azcoitia Iñigo , DonCarlos Lydia L. , Garcia‐Segura Luis M. 
Published: March 2003

SummaryHuman aging is associated with a decrease of circulating gonadal steroid hormones. Since these hormones act as trophic factors for neurones and glia, it is possible that the decrease in sex steroid levels may contribute to the increased risk of neurodegenerative disorders with advanced age. Sex steroids are neuroprotective in several animal models of central and peripheral neurodegenerative diseases, and clinical data suggest that these hormones may reduce the risk of neural pathology in aged humans. Potential therapeutic approaches for aged‐associated neural disorders may emerge from studies conducted to understand the mechanisms of action of sex steroids in the nervous system of aged animals. Alterations in the endogenous capacity of the aged brain to synthesize and metabolize sex steroids, as well as possible aged‐associated modifications in the signalling of sex steroid receptors in the nervous system, are important areas for future investigation.
Rent Sharing in Multi‐Site Hog Production
Authors: Cozzarin Brian P. , Westgren Randall E. 
Published: March 2003

AbstractA firm‐level model of three‐site hog production is used compare a franchise organizational structure to a three‐firm alliance. The results of the simulations imply that the franchise system is better equipped to mitigate underproduction in the nursery and finishing units, the nursery and finishing units lose relatively more profit than they otherwise would in an alliance. The pig‐space guatantee does little to offset the financial risk for the nursery and finishing units when underproduction occurs upstream (breeding, gestation, and farrowing unit).
Unilateral Resource Management in a Two‐Country General Equilibrium Model of Trade in a Renewable Fishery Resource
Authors: Emami Ali , Johnston Richard S. 
Published: March 2003

AbstractWe explore the effects of free trade in a renewable natural resource between two countries in the presence of incomplete property rights. While resource management by one country may benefit one or both trading partners, we demonstrate that resource management by only one of the partners may reduce welfare for both, when compared to the case in which neither manages its resource sector. These trade‐induced losses may be reduced through import tariffs and production subsidies on the resource good or by permitting harvest beyond the rent‐maximizing level. Our preliminary work suggests that the World Trade Organization (WTO) and North American Free Trade Agreement (NAFTA) policy makers should not always insist on free trade and resource management. Rather, they must pay careful attention to the particular relationships between trade conditions and natural resource policies among trading nations.
The Impact of the Canada‐United States Free Trade Agreement on U.S. Wine Exports
Authors: Heien Dale , Sims Eric N. 
Published: March 2003

AbstractOn 1 January 1989 the Canada‐United States Free Trade Agreement went into effect. The agreement reduced the restrictions on the importation and marketing of wine produced in the United States. This article analyzes the impact of this lessening on United States wine exports to Canada. A demand relation for United States exports to Canada is estimated and then used to decompose the effects into their proximate causes. These causes are (a) own‐price and exchange rate effects, (b) substitute price and exchange rate effects, (c) changes in real income in Canada, (d) tariff removal effects, and (e) removal of nontariff trade barriers by Canada.
Trade Liberalization and Agricultural Chemical Use: United States and Mexico
Authors: Williams Shon P. , Shumway C. Richard 
Published: March 2003

AbstractTo anticipate the likely effects of recent trade agreements with Mexico on the environment and food safety, this paper examines changes in agricultural chemical use. Econometric estimation and simulation suggest that the combined effects of the North American Free Trade Agreement (NAFTA), economic growth, research investment, and farm policy are expected to increase chemical usage substantially in the United States and undoubtedly lead to greater groundwater contamination. In Mexico, the expected effects are a substantial increase in fertilizer use but a decrease in pesticide use. Increases in private research investment are expected to increase the use of both types of chemicals, but increases in public research investment in the United States are not.
Aggregation without Separability: Tests of the United States and Mexican Agricultural Production Data
Authors: Davis George C. , Lin Ni , Shumway C. Richard 
Published: March 2003

AbstractThe generalized composite commodity theorem (GCCT) and testing procedure is extended to test for consistent aggregation of the United States and Mexican agricultural production data in each category for which earlier tests rejected homothetic separability. Nonrejected GCCT and separability hypotheses provide empirical support for aggregating all the United States agricultural outputs into as few as two categories: crops and livestock. Mexican agricultural outputs also can be aggregated into as few as two categories. Support for aggregating all outputs into a single category is ambiguous in both countries and is only provided by the GCCT.
Optimal Temporal Policies in Fluid Milk Advertising
Authors: Vande Kamp Philip R. , Kaiser Harry M. 
Published: March 2003

AbstractThis study develops an approach to obtain optimal temporal advertising strategies when consumers' response to advertising is asymmetric. Using this approach, optimal strategies for generic fluid milk advertising in New York City are determined. Results indicate that pulsed advertising policies are significantly more effective in increasing demand than a uniform advertising policy. Sensitivity analyses show that the optimal advertising policies are insensitive to reasonable variations in interest rates and the inclusion of milk demand seasonality in the model. Also less asymmetric responses to advertising are found to result in shorter optimal pulsing cycles and reduced intensity of advertising pulses.
No Such Thing as a Free Safe Lunch: The Cost of Food Safety Regulation in the Meat Industry
Authors: Antle John M. 
Published: March 2003

AbstractThis study develops theoretical and econometric cost function models for the meat industry to test the hypothesis of safety exogeneity, i.e., that product safety does not affect productive efficiency. Using plant‐level data from the Census of Manufactures, this hypothesis is rejected. Estimates of the impacts of food safety regulation on variable cost of production in the beef, pork, and poultry industries show that the efficiency costs of food safety regulations could plausibly exceed benefits estimated by the U.S. Department of Agriculture. Costs of regulation per pound of meat are found to be size neutral for all but the smallest plants.
Scale Economies and Consolidation in Hog Slaughter
Authors: MacDonald James M. , Ollinger Michael E. 
Published: March 2003

AbstractWe use establishment based panel data to estimate a cost function which identifies the role of scale economies in hog slaughter consolidation. We find modest but extensive technological scale economies in the 1990s, and they became more important over time. But wages rose sharply with plant size through the 1970s, and those wage premiums generated a pecuniary scale diseconomy that largely offset the effects of technological scale economies. The size‐wage relation disappeared in the 1980s; with growing technological scale economies and disappearing pecuniary diseconomies, large plants realized growing cost advantages over smaller plants, and production shifted to larger plants.
Efficient Redistribution Using Quotas and Subsidies in the Presence of Misrepresentation and Cheating
Authors: Giannakas Konstantinos , Fulton Murray 
Published: March 2003

AbstractThis paper introduces misrepresentation and cheating into the policy analysis of output quotas and subsidies. Analytical results show that when cheating occurs output quotas are a less efficient means of income redistribution than is traditionally believed. As well, cheating increases the transfer efficiency of output subsidies. The result is that an all‐or‐nothing choice between quotas and subsidies will generally favor the use of subsidies. A combination of quotas and subsidies, however, usually remains the most efficient means of income redistribution through market intervention.
Surplus Distribution from the Introduction of a Biotechnology Innovation
Authors: Falck‐Zepeda José Benjamin , Traxler Greg , Nelson Robert G. 
Published: March 2003

AbstractWe examine the distribution of welfare from the introduction of Bt cotton in the United States in 1996. The welfare framework explicitly recognizes that research protected by intellectual property rights generates monopoly profits, and makes it possible to partition these rents among consumers, farmers, and the innovating input firms. We calculate a total increase in world surplus of $@@‐@@240.3 million for 1996. Of this total, the largest share (59%) went to U.S. farmers. The gene developer, Monsanto, received the next largest share (21%), followed by U.S. consumers (9%), the rest of the world (6%), and the germplasm supplier, Delta and Pine Land Company (5%).
Convergence in U.S. Productivity Growth for Agriculture: Implications of Interstate Research Spillovers for Funding Agricultural Research
Authors: McCunn Alan , Huffman Wallace E. 
Published: March 2003

AbstractState crop, livestock,and aggregate agricultural total factor productivity (TFP) data, 1950–82, are examined for evidence of convergence to a single TFP level (σ‐convergence) or to a steady state rate of growth (β‐ or conditional convergence). Our empirical results do not support σ‐convergence but do support β‐convergence. The rate of β ‐convergence is variable and depends on research and development (R…D) spillins from other states,private R…D, and farmers' schooling. The finding of strong positive interstate spillover effects implies that independent state planning of agricultural research is inefficient and cooperation across states boundaries including establishment of new political jurisdictions for financing public agricultural research can enhance efficiency.
Foreign Transfers and Tropical Deforestation: What Terms of Conditionality?
Authors: van Soest Daan , Lensink Robert 
Published: March 2003

AbstractThe international community considers the possibility of using aid as an instrument to improve natural resource conservation in developing countries. By making the amount of transfers dependent on the efforts of the recipient countries to improve conservation, appropriate incentives can be given. We propose a transfer function in which developing countries are linearly rewarded for having a positive stock of forest, andwhere the amount of donations is negatively relatedto the rate of deforestation. This transfer function enables the international community to improve long‐term forest conservation as well as the rate of deforestation during the adjustment period.
Joint Production and Averting Expenditure Measures of Willingness to Pay: Do Water Expenditures Really Measure Avoidance Costs?
Authors: Abrahams Nii Adote , Hubbell Bryan J. , Jordan Jeffrey L. 
Published: March 2003

AbstractA multinomial selection model of averting behavior in response to water contamination risks is estimatedfor Georgia residents. Measures of non‐health related water quality (taste, odor, and appearance) are incorporated into the model to account for joint production of utility and health. The model examines the choice between bottled, filtered tap, and unfiltered tap water. Results of the estimation indicated that perceived risk from tap water, concern about water quality (taste, odor, and appearance of tap water), race, and age are the most important determinants of bottled water selection. Information regarding current or prior problems with tap water, perceived risk from tap water, and income are the most important determinants of water filter selection. Adjusting for quality differences between tap and bottled water, we show that averting costs estimates using bottled water expenditures would lead to an overstatement of avoidance costs by about 12%.
A Semiparametric Distribution for Willingness to Pay and Statistical Inference with Dichotomous Choice Contingent Valuation Data
Authors: An Mark Yuying 
Published: March 2003

AbstractThis paper proposes a semiparametric willingness to pay distribution and discusses several aspects of statistical inference with dichotomous choice contingent valuation data. We study likelihood‐based estimation of the model parameters with and without controlling for unobserved heterogeneity, estimation of the mean and median willingness to pay, and specification tests. These statistical procedures are implemented using a data set. In this application we find that a parametric model is rejected in favor of our semiparametric model, that the heterogeneity can be adequately controlled using a simple density, and that the semiparametric model offers more robust mean willingness to pay estimates.
The Composition of Rural Employment Growth in the “New Economy”
Authors: Wojan Timothy R. 
Published: March 2003

AbstractThis article examines changes in the patterns of occupational employment in urban and rural labor markets in seven southern states between 1970 and 1990. A method is developed for assessing whether occupational employment patterns are becoming more differentiated over time. The analysis identifies a process of increasing similarity across all occupational groups between 1970 and 1980. In contrast, the 1980–90 period is characterized by increasing rural specialization in Operator (low‐skill) occupations amid increasing similarity in four of nine inclusive occupational categories. These results provide partial support for conjectures regarding greater differentiation of tasks performed in rural and urban labor markets.
Broiler Production Contracts as a Multi‐Agent Problem: Common Risk, Incentives and Heterogeneity
Authors: Goodhue Rachael E. 
Published: March 2003

AbstractThe broiler industry presents two puzzles regarding production contracts: why do processors control growers' inputs, and why do they use a statistically insufficient estimator to calculate growers' compensation? This paper provides an agency theoretic framework that explains these puzzles in terms of processors' response to grower heterogeneity and production risk and to grower risk aversion. Processors control inputs to reduce the information rents paid to agents. By forcing agents to bear additional income risk through the use of an imprecise estimator, processors can increase profits, due to the combined moral hazard‐adverse selection nature of the informational problem.
Setting Efficient Incentives for Agricultural Research: Lessons from Principal‐Agent Theory
Authors: Huffman Wallace E. , Just Richard E. 
Published: March 2003

AbstractA conceptual analysis of important issues in the organization and management of academic research is presented. Principal‐agent theory is applied to derive optimal compensation schemes for scientists when they differ in ability, risk aversion, cost of effort, and reservation utility, and to show the optimal trade‐off between institutional risk and scientists' abilities. Implications for an efficient organization of research are derived, including how scientists' incentives should be structured to elicit optimal research efforts and direction, whether research direction should be centralized or decentralized, and whether the organization of research should be through external competitive grantsor program and institutional funding.
Size and Productivity in the U.S. Milling and Baking Industries
Authors: Buccola Steven , Yoko Fujii , Yin Xia 
Published: March 2003

AbstractFrom the late 1950s through mid‐1990s, productivity growth in U.S. grain milling and feed manufacturing has been consistently strong and positive. In grain milling, approximately 15% of the growth is due to size economies. Technical change has been capital‐using, increasingly material‐saving, and, in recent years, decreasingly labor‐saving or increasingly labor‐using. The quality of capital has risen relative to that of labor and materials. In all but the baking industry, capital intensification and incentives for plant size growth remain unabated.
Hedging Multiple Price Uncertainty in International Grain Trade
Authors: Haigh Michael S. , Holt Matthew T. 
Published: March 2003

AbstractCommodity and freight futures contracts are analyzed for their effectiveness in reducing uncertainty for international traders. A theoretical model is developed for a trader exposed to several types of risk. OLS hedge ratio estimation is compared to the SUR and the multivariate GARCH methodologies. Explicit modeling of the time‐variation in hedge ratios via the multivariate GARCH methodology, using all derivatives, and taking into account dependencies between prices, results in reductions in risk, even after accounting for transaction costs. Results confirm that while the commodity futures contracts are important for hedging risk, freight futures are a useful mechanism for reducing risk.
The Demand for Hedging and the Value of Hedging Opportunities
Authors: Frechette Darren L. 
Published: March 2003

AbstractHedging strategies typically assume that hedging is costless and that only one futures market exists. When these assumptions are dropped, the demand for hedging is shown to depend on basis risk, price risk, and the hedger's risk preference. The marginal and incremental value of hedging opportunities are computed for the general cases of one and two markets and applied to the specific case of Pennsylvania dairy input hedging.
A Strong Test of the von Liebig Hypothesis
Authors: Berck Peter , Geoghegan Jacqueline , Stohs Stephen 
Published: March 2003

AbstractAn implication of the von Liebig hypothesis is that crop‐production functions have right‐angle isoquants. This article presents a nonparametric estimation of right‐angle isoquant production functions. It then describes a new test for right‐angle isoquants. The procedures are used to test experimental data on corn and wheat.
Investment under Uncertainty and Dynamic Adjustment in the Finnish Pork Industry
Authors: Pietola Kyösti S. , Myers Robert J. 
Published: March 2003

AbstractA stochastic dual model of investment under uncertainty is used to investigate structural adjustment in the Finnish hog industry. Value function restrictions are found to be comparable to those in existing dual models assuming deterministic state variables. The model also allows for an asymmetry in investment response during capital expansion and contraction phases. Empirical results show that investments respond negatively to increased uncertainty and that labor adjusts more slowly during contraction phases than during expansions. Results on economies of size, uncertainty effects, and adjustment rigidities have important implications for hog industry response to Finland's entry into the EU.
Land Tenure and the Adoption of Conservation Practices
Authors: Soule Meredith J. , Tegene Abebayehu , Wiebe Keith D. 
Published: March 2003

AbstractWe use a logit adoption model with data on 941 U.S. corn producers from the 1996 Agricultural Resource Management Study to analyze the influence of land tenure on the adoption of conservation practices. We extend previous analyses by distinguishing renters according to lease type and by distinguishing practices according to the timing of costs and returns. We find that cash‐renters are less likely than owner‐operators to use conservation tillage, but share‐renters are not. Both cash‐renters and share‐renters are less likely than owner‐operators to adopt practices that provide benefits only over the longer term (grassed waterways, stripcropping, and contour farming).