39 research outputs found
ECONOMICS OF MANAGING INVASIVE PEST SPECIES: EXCLUSION AND CONTROL
An important policy decision in managing invasive species is how to allocate resources between activities aimed at preventing the arrival of new pests - including additional arrivals of existing pests - and activities aimed at reducing the damages done by species that are already here. We develop a dynamic model for managing a generic invasive pest with an uncertain arrival date. The optimal conditions reveal that it is generally more efficient to spend a larger share of outlays for exclusion activities before a species arrives than after it is known to be here. They also show that outlays should be allocated such that the marginal costs of control measures equal the benefits from the marginal reduction of the species' population growth rate, and the marginal costs of exclusion measures equal the benefits from the marginal reduction of the rate of subsequent arrivals.Environmental Economics and Policy,
Induced-Innovation and Invasive Species Management
Public policy for managing invasive species has largely focused on preventive measures prior to detection (stage 1) and on the use of chemical/mechanical or biological control measures after the establishment and dispersion of the invasive species (stage 2). Optimal management policy depends both on the initial stock of the invasive species and on the costs associated with conventional control measures. However, little attention has focused on how an induced technology such as Bt corn and Bt cotton is developed and adopted by farmers (stage 3), or how it affects the manageability of economic and ecological damages from an invasive species. This analysis evaluates the optimal allocation of management resources between preventive and control measures for invasive species by incorporating induced technology under uncertainty into a conventional dynamic model of invasive species management.Invasive species, preventive measures, control measures, induced technology, hazard function, optimal control, comparative dynamic analysis, Environmental Economics and Policy, Production Economics,
World Agriculture and Climate Change: Economic Adaptations
Recent studies suggest that possible global increases in temperature and changes in precipitation patterns during the next century will affect world agriculture. Because of the ability of farmers to adapt , however, these changes are not likely to imperil world food production. Nevertheless, world production of all goods and services may decline, if climate change is severe enough or if cropland expansion is hindered. Impacts are not equally distributed around the world.climate change, world agriculture, Environmental Economics and Policy,
Permanence of Carbon Sequestered in Forests under Uncertainty
In this paper we examine the issue of permanence in the context of sequestering carbon through afforestation. We develop a dynamic nested optimal control model of carbon sequestration associated with the decision to afforest a tract of land given there are uncertainties associated with fire and insect/disease hazards. Conceptually, these potential hazards are similar in that their occurrence at any time t is uncertain and landowners can take specific actions – although generally different actions - in any time period t to reduce the probability of sustaining losses related to them. The hazards differ, however, in that fire represents a large loss in carbon at a moment in time, while insect/disease infestations are more likely to be reflected in a period of significant slowing of the rate of carbon accumulation than was anticipated followed by a sustained period of slowly decreasing carbon losses. The nature of these losses will influence the design of incentives under GHG mitigation frameworks that require carbon losses to be replaced as well as the strategies farmers adopt to deal with the uncertainties associated with these events occurring.carbon sequestration, uncertainty, optimal control, hazard function, forestry, permanence, Environmental Economics and Policy, Land Economics/Use,
Prevention or Control: Optimal Government Policies for Invasive Species Management
We present a conceptual, but empirically applicable, model for determining the optimal allocation of resources between exclusion and control activities for managing an invasive species with an uncertain discovery time. This model is used to investigate how to allocate limited resources between activities before and after the first discovery of an invasive species and the effects of the characteristics of an invasive species on limited resource allocation. The optimality conditions show that it is economically efficient to spend a larger share of outlays for exclusion activities before, rather than after, a species is first discovered, up to a threshold point. We also find that, after discovery, more exclusionary measures and fewer control measures are optimal, when the pest population is less than a threshold. As the pest population increases beyond this threshold, the exclusionary measures are no longer optimal. Finally, a comparative dynamic analysis indicates that the efficient level of total expenditures on preventive and control measures decreases with the level of the invasive species stock and increases with the intrinsic population growth rate, the rate of additional discoveries avoided, and the maximum possible pest population.invasive species, exclusion, control, eradication, public expenditures, Environmental Economics and Policy, Resource /Energy Economics and Policy,
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Toward a new methodology for estimating the marginal social rate of return to public investments in higher education
The United States invests tens of billions of dollars in higher
education each year. This had led many researchers to estimate the
marginal and average rates of return to these expenditures. Past
works, however, have been partial in scope. That is, they have
counted only the benefits of higher education which result from the
increased earnings of college graduates over people with only a high
school diploma. Additional benefits, such as lower consumer prices
which result from a more productive work force, have not been considered
previously and empirically estimated.
The purpose of the present study was to use the techniques of
applied welfare analysis to develop a new approach to estimating the
marginal social rate of return to investments in higher education.
The annual economic benefits to society from increased levels of
public support for higher education are estimated by changes in areas
of consumer and producer surplus associated with the general equilibrium
supply and demand curves for college educated labor. These
benefits are then equated with the increased expenditures using a
standard discount formula, and a marginal social rate of return is
calculated.
Data for this study come from the Bureau of the Census and the
National Center for Educational Statistics. The supply and demand
curves for the labor of college graduates are estimated by ordinary
least squares regression treating each state as a separate labor
market.
Our analysis suggests that further increases in the level of
public expenditures for higher education may not be justified using
cost benefit analysis techniques. The weakness of the statistical
properties associated with our empirical results, however, indicates
considerable additional research is necessary prior to making a
policy recommendation on the issue
ECONOMICS OF SEQUESTERING CARBON IN THE U.S. AGRICULTURAL SECTOR
Atmospheric concentrations of greenhouse gases can be reduced by withdrawing carbon from the atmosphere and sequestering it in soils and biomass. This report analyzes the performance of alternative incentive designs and payment levels if farmers were paid to adopt land uses and management practices that raise soil carbon levels. At payment levels below $10 per metric ton for permanently sequestered carbon, analysis suggests landowners would find it more cost effective to adopt changes in rotations and tillage practices. At higher payment levels, afforestation dominates sequestration activities, mostly through conversion of pastureland. Across payment levels, the economic potential to sequester carbon is much lower than the technical potential reported in soil science studies. The most cost-effective payment design adjusts payment levels to account both for the length of time farmers are willing to commit to sequestration activities and for net sequestration. A 50-percent cost-share for cropland conversion to forestry or grasslands would increase sequestration at low carbon payment levels but not at high payment levels.Carbon sequestration, greenhouse gas mitigation, afforestation, conservation tillage, no-till, incentive design, leakage, carbon stock, permanence, Environmental Economics and Policy,
Proteome changes in platelets activated by arachidonic acid, collagen, and thrombin
<p>Abstract</p> <p>Background</p> <p>Platelets are small anucleated blood particles that play a key role in the control of bleeding. Platelets need to be activated to perform their functions and participate in hemostasis. The process of activation is accompanied by vast protein reorganization and posttranslational modifications. The goal of this study was to identify changes in proteins in platelets activated by different agonists. Platelets were activated by three different agonists - arachidonic acid, collagen, and thrombin. 2D SDS-PAGE (pI 4-7) was used to separate platelet proteins. Proteomes of activated and resting platelets were compared with each other by Progenesis SameSpots statistical software; and proteins were identified by nanoLC-MS/MS.</p> <p>Results</p> <p>190 spots were found to be significantly different. Of these, 180 spots were successfully identified and correspond to 144 different proteins. Five proteins were found that had not previously been identified in platelets: protein CDV3 homolog, protein ETHE1, protein LZIC, FGFR1 oncogene partner 2, and guanine nucleotide-binding protein subunit beta-5. Using spot expression profile analysis, we found two proteins (WD repeat-containing protein 1 and mitochondrial glycerol-3-phosphate dehydrogenase) that may be part of thrombin specific activation or signal transduction pathway(s).</p> <p>Conclusions</p> <p>Our results, characterizing the differences within proteins in both activated (by various agonists) and resting platelets, can thus contribute to the basic knowledge of platelets and to the understanding of the function and development of new antiplatelet drugs.</p
An Ultrasound Assisted Anchoring Technique (BoneWelding® Technology) for Fixation of Implants to Bone – A Histological Pilot Study in Sheep
The BoneWelding® Technology offers new opportunities to anchor implants within bone. The technology melted the surface of biodegradable polymer pins by means of ultrasound energy to mould material into the structures of the predrilled bone. Temperature changes were measured at the sites of implantation in an in vitro experiment. In the in vivo part of the study two types of implants were implanted in the limb of sheep to investigate the biocompatibility of the method. One implant type was made of PL-DL-lactide (PLA), the second one was a titanium core partially covered with PLA. Healing period was 2 and 6 months, with 3 sheep per group. Bone samples were evaluated radiologically, histologically and histomorphometrically for bone remodeling and inflammatory reactions. Results demonstrated mild and short temperature increase during insertion. New bone formed at the implant without evidence of inflammatory reaction. The amount of adjacent bone was increased compared to normal cancellous bone. It was concluded that the BoneWelding® Technology proved to be a biocompatible technology to anchor biodegradable as well as titanium-PLA implants in bone