DTD level authorization in XML documents with usage control

[Summary]: In recent years an increasing amount of semi-structured data has become important to humans and programs. XML promoted by the World Wide Web Consortium (W3C) is rapidly emerging as the new standard language for semi-structured data representation and exchange on the Internet. XML documents may contain private information that cannot be shared by all user communities. So securing XML data is becoming increasingly important and several approaches have been designed to protect information in a website. However, these approaches typically are used at file system level, rather than for the data in XML documents. Usage control has been considered as the next generation access control model with distinguishing properties of decision continuity. Usage control enables finer-grained control over usage of digital objects than that of traditional access control policies and models. In this paper, we present a usage control model to protect information distributed on the web, which allows the access restrictions directly at DTD-level and XML document-level. Finally, comparisons with related works are analysed

Authorization algorithms for permission-role assignments

Permission-role assignments (PRA) is one important process in Role-based access control (RBAC) which has been proven to be a flexible and useful access model for information sharing in distributed collaborative environments. However, problems may arise during the procedures of PRA. Conflicting permissions may assign to one role, and as a result, the role with the permissions can derive unexpected access capabilities. This paper aims to analyze the problems during the procedures of permission-role assignments in distributed collaborative environments and to develop authorization allocation algorithms to address the problems within permission-role assignments. The algorithms are extended to the case of PRA with the mobility of permission-role relationship. Finally, comparisons with other related work are discussed to demonstrate the effective work of the paper

Demand for Wildlife Hunting in British Columbia

We present estimates of the demand for hunting licenses by residents and non residents in British Columbia for the period 1971–2000. We obtain estimates of both short-run and long- run price elasticities and discuss their revenue implications for future fee increases. We find the demand by non residents to be strongly correlated with U.S. income variation over the business cycle, but find no such role for cyclical income variation for resident hunters. The ability of the government to increase revenues from resident hunters turns out to be limited, particularly in the long run, while greater opportunities exist to raise revenues from U.S. hunters as short- and long-run price elasticities of demand are quite inelastic. We argue that conservation surcharges on foreign hunters are one way to capture more of the resource rent.recreation demand, resource revenues and rent capture, conservation surcharges

Demand for Wildlife Hunting in British Columbia

We present estimates of the demand for hunting licenses by residents and non residents in British Columbia for the period 1971–2000. We obtain estimates of both short-run and long-run price elasticities and discuss their revenue implications for future fee increases. We further find the demand by non residents to be strongly correlated with U.S. income variation over the business cycle; however, we find no such role for cyclical income variation for resident hunters. Finally, we demonstrate that hunters respond differently to conservation surcharges on hunting licenses relative to direct licensing charges, which has implications for policy makers introducing environmental surcharges in various contexts.recreation demand, environmental surcharges, resource revenues and rent capture

Divergence between WTA and WTP Revisited: Livestock Grazing on Public Range

The research reported here provides further empirical support for the contention that there is a divergence between WTA and WTP. The conclusion is based on results from a 2002 survey of Nevada ranchers that asked about willingness to pay for public forage and WTA compensation to part with grazing rights. WTP and WTA are estimated simultaneously, with the estimators used to demonstrate a statistically significant divergence between WTP and WTA. The simultaneous estimation allows us to identify ranch characteristics that influence the discrepancy in valuations. Ranch size, public grazing allotment, financial distress, and long term commitment to ranching are all significant influences on the disparity. We interpret these results both with respect to general differences in welfare measures and with respect to ranch policy.contingent valuation methods, dichotomous choice surveys, WTA versus WTP, grazing rights and public forage

The Effect of Uncertainty on Contingent Valuation Estimates: A Comparison

We examine the impact of uncertainty on contingent valuation responses using (1) a survey of Canadian landowners about willingness to accept compensation for converting cropland to forestry and (2) a survey of Swedish residents about willingness to pay for forest conservation. Five approaches from the literature for incorporating respondent uncertainty are used and compared to the traditional RUM model with assumed certainty. The results indicate that incorporating uncertainty has the potential to increase fit, but could introduce additional variance. While some methods for uncertainty are an improvement over traditional approaches, we caution against systematic judgments about the effect of uncertainty on contingent valuation responses.respondent uncertainty, willingness to accept, contingent valuation

Are Agricultural Values a Reliable Guide in Determining Landowners’ Decisions to Create Carbon Forest Sinks?

This research examines the effects of various factors on farmer participation in agricultural tree plantations for economic, environmental, social and carbon-uptake purposes, and potential costs of sequestering carbon through afforestation in western Canada. Using data from a survey of landowners, a discrete choice random utility model is used to determine the probability of landowners’ participation and corresponding mean willingness to accept (WTA) compensation for a tree-planting program. WTA includes positive and negative benefits to landowners from planting trees, benefits not captured by foregone returns from agricultural activities on marginal land. Estimates of WTA are less than foregone returns, but even so average costs of creating carbon credits still exceed their projected value under a CO2-emissions trading scheme.Willingness to accept compensation for tree planting, afforestation, climate change

Does Inclusion of Landowners’ Non-Market Values Lower Costs of Creating Carbon Forest Sinks?

This research examines effects of various factors on farmer participation in agricultural tree plantations for economic, environmental, social and carbon-uptake purposes. Using data from a survey of Canadian agricultural landowners, a discrete choice random utility model is used to determine the probability of farmers’ participation and corresponding mean willingness to accept (WTA) compensation for a tree-planting program. WTA includes positive and negative nonmarket benefits to landowners from planting trees. Estimates of WTA are less than foregone agricultural rents, but average costs of creating carbon credits still exceed their projected value under a CO2-emissions trading scheme.Willingness to accept compensation for tree planting, afforestation, climate change