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41.
ABSTRACT. Deforestation caused by concession logging is often the result of harvest decisions which focus on short-run profits rather than on long-run sustainable harvest yields. A sequential-decision model of this type of behavior is here developed which focuses on a logger's annual decisions of whether or not to remain in compliance with the terms of a concession contract. The contract stipulates harvesting procedures for a sustained forest yield, and noncompliance is taken to result in deforestation. An optimal decision policy for the concession logger is characterized in terms of optimal-stopping theory, and is employed to construct payoff incentives which encourage compliance. In particular, a forest management problem is formulated which focuses on the effectiveness of partial inspection policies in deterring noncompliant behavior. General necessary and sufficient conditions for the effectiveness of such policies are established, and are given a more operational form for the Markov case. A numerical example based on actual concession-contract data is also developed which suggests certain policy implications. 相似文献
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Tony Waldron 《International Journal of Osteoarchaeology》1997,7(3):241-247
A case of prostatic carcinoma is described in the skeleton of a named individual who died in 1834. The tumour was recognized from widespread periosteal new bone throughout the skeleton and by the presence of sclerosing metastases in many bones, including the pelvis and all the vertebrae. A number of features of the disease present here are said to be uncommon in modern patients, including spiculated periosteal new bone and some degree of spinal stenosis. In two previous cases of prostatic carcinoma described in the literature, periosteal new bone was a prominent feature and was probably responsible for the disease being recognized. It is likely that if skeletons from mature males were routinely X-rayed, considerably more cases would be noted and a more accurate estimate of the prevalence of this disease in the past would thus be ascertained. © 1997 John Wiley & Sons, Ltd. 相似文献
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Tony Waldron 《International Journal of Osteoarchaeology》1993,3(3):213-218
The distribution of osteoarthritis of the hands was studied in 101 skeletons from archaeological sites in England. The results are similar to those found in epidemiological studies of modern populations. Osteoarthritis of the hands was more common in females than in males, and in females tended to involve a greater number of joints. The distal and proximal interphalangeal joints were commonly affected, the former more frequently than the latter, but otherwise the disease was largely confined to the first ray of the hand, centred on the trapezium. It is concluded that the pattern of osteoarthritis in the hand has probably not changed greatly over several hundred years. 相似文献
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This article proposes a new method of mapping domestic preferences and their effect on Australian foreign policy from the perspective of three distinct ‘currents of thought’s flowing through Australian society and policy makers about Australia and the world. Traditionalism prioritises security relationships with ‘great and powerful friends’s; Seclusionism stresses autarky and minimal international involvement; Internationalism advocates a creative, multilateralist role in building international stability and prosperity. A currents of thought approach, by looking for an underlying motivation for Australian foreign policy actions, assists in understanding the policy's intent, identifying its supporters and detractors, and in anticipating what types of policy responses will be motivated by different international stimuli. It is also useful for further understanding the underlying processes behind the broad changes of direction in Australian foreign policy. 相似文献
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This paper seeks to place policy research undertaken in the Yorkshire and East London regions of the UK within the broader context of regional innovation system building. In particular, it attempts to draw out the releasing factors and conditions that shaped stakeholder relationships in these two EU Objective Two regions during the 1990s. This is undertaken with a view to drawing out conclusions about the extent of autonomy, institutional lock-in and compatibility within regional governance. The extent to which such EU stimulated influences are relevant to the practice of regional technological development is explored in areas which have experienced industrial restructuring. 相似文献
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Tony Banks 《Development and change》2001,32(4):717-740
It is widely perceived that the degradation of China’s rangelands has accelerated since the introduction of rural reforms in the late 1970s. The popular explanation for this phenomenon has been that a ‘tragedy of the commons’ exists, as privately‐owned livestock are being grazed on ‘common’ land. Since the passing of the Rangeland Law in 1985, Chinese pastoral tenure policy has emphasized the establishment of individual household tenure as a necessary condition for improving incentives for sustainable rangeland management. Yet household tenure has yet to be effectively established in many pastoral regions. The first objective of this article is to describe pastoral tenure arrangements in northern Xinjiang‐Uygur Autonomous Region. Its second objective is to explain pastoral tenure arrangements, particularly the observed persistence of collective action. It is argued that there is no ‘tragedy of the commons’ and that it is characteristics of rangeland resources and the social environment that give rise to the particular types of institutional arrangements found. 相似文献