3,679 research outputs found

    Systematic review of birth cohort studies in South East Asia and Eastern Mediterranean regions

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    Few longitudinal studies of children have taken place in the developing world, despite child mortality being concentrated there. This review summarises the methodologies and main outcomes of longitudinal studies of pre-school children (0 to 59 months) in the World Health Organization’s South East Asia (SEA) and Eastern Mediterranean (EM) Regions

    Forestry Economics: Principles and Practice

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    This review discusses bioeconomic models of the forest and uses them to explore policy options for forest management. The main type of bioeconomic model used is based on a biomass model of the growth of the forest, similar to the biomass model widely used in fishery economics. However a more detailed model, similar to the cohort-based models of fish stocks, which simulates the growth of subsections of the forest is also referred to. The bioeconomic models are based on simple assumptions about prices and costs - mainly that the forest industry, as a small part of the economy, is a price taker in both output and input markets. The models were initially used to examine the harvesting policy which would maximise the net present value of the timber produced by the forest. However it was recognised that non-timber values are becoming increasingly important and must be accounted for in the development of an optimal forest strategy. Case Studies consider some of the issues raised in the paper in greater detail.

    Allocating Yellowfin Tuna Between the Multispecies Purse Seine and Longline Fleets

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    Yellowfin tuna in the western Pacific are harvested as juveniles by purse seiners and as adults by longliners. The study presents estimates of the multi-species harvest technology of these two types of vessel operating in Papua New Guinea's Exclusive Economic Zone. The results, together with price and cost information and estimates of the impact of the purse seine catch on the catch rates of longline vessels are used to perform a benefit/cost analysis of a reallocation of juvenile yellowfin through a one percent decline in purse seine harvest in PNG's EEZ. The marginal benefit of investment in the yellowfin stock is found to exceed that of marginal cost, suggesting that there may be an economic case for a reallocation.resource sharing, multispecies fisheries, yellowfin tuna, Environmental Economics and Policy, International Development, International Relations/Trade, Resource /Energy Economics and Policy,

    A Note on Optimal Effort in the Maldivian Tuna Fishery

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    This note argues that spatial considerations and travel costs should be taken into account in devising tax/subsidy regulations for island-based tuna fisheries. In particular, the effect of a landings tax on distant fishing grounds should be considered when setting the level of the tax. A fuel subsidy is suggested as a means of offsetting the impact of the landings tax on marginal grounds.Environmental Economics and Policy, Research Methods/ Statistical Methods, Resource /Energy Economics and Policy,

    Taking Account of Non-Timber Values in Harvest Decisions in the Southern Forest of Tasmania

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    This paper examines the optimal use of a site containing standing timber, taking account of both timber and non-timber values. It discusses the range of non-timber values yielded by a typical site in the southern forest of Tasmania. Taking that site for illustrative purposes, it calculates the relationships between age of stand, extent of timber and non-timber values, and optimal cutting age, using a spreadsheet model. It finds that for a stand with moderate potential environmental benefits there is a period of its life during which it is optimal to log. This segment narrows, and eventually disappears, as potential environmental benefits increase.

    Induced matter: Curved N-manifolds encapsulated in Riemann-flat N+1 dimensional space

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    Liko and Wesson have recently introduced a new 5-dimensional induced matter solution of the Einstein equations, a negative curvature Robertson-Walker space embedded in a Riemann flat 5-dimensional manifold. We show that this solution is a special case of a more general theorem prescribing the structure of certain N+1-dimensional Riemann flat spaces which are all solutions of the Einstein equations. These solutions encapsulate N-dimensional curved manifolds. Such spaces are said to "induce matter" in the sub-manifolds by virtue of their geometric structure alone. We prove that the N-manifold can be any maximally symmetric space.Comment: 3 page

    The metabolic overdrive hypothesis:hyperglycolysis and glutaminolysis in bipolar mania

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    Evidence from diverse areas of research including chronobiology, metabolomics and magnetic resonance spectroscopy indicate that energy dysregulation is a central feature of bipolar disorder pathophysiology. In this paper, we propose that mania represents a condition of heightened cerebral energy metabolism facilitated by hyperglycolysis and glutaminolysis. When oxidative glucose metabolism becomes impaired in the brain, neurons can utilize glutamate as an alternative substrate to generate energy through oxidative phosphorylation. Glycolysis in astrocytes fuels the formation of denovo glutamate, which can be used as a mitochondrial fuel source in neurons via transamination to alpha-ketoglutarate and subsequent reductive carboxylation to replenish tricarboxylic acid cycle intermediates. Upregulation of glycolysis and glutaminolysis in this manner causes the brain to enter a state of heightened metabolism and excitatory activity which we propose to underlie the subjective experience of mania. Under normal conditions, this mechanism serves an adaptive function to transiently upregulate brain metabolism in response to acute energy demand. However, when recruited in the long term to counteract impaired oxidative metabolism it may become a pathological process. In this article, we develop these ideas in detail, present supporting evidence and propose this as a novel avenue of investigation to understand the biological basis for mania.</p