1,104 research outputs found

    WETLANDS, WILDLIFE, AND WATER QUALITY: TARGETING AND TRADE OFFS

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    Cost-effective targeting of conservation activities has only recently been addressed by economists. Most work to date has focused on finding the best locations to set aside land for the protection of biodiversity. An economic approach to the problem, where biodiversity reserve networks are delineated to maximize the number of species protected subject to a budget constraint, has been shown to be much more cost-effective than the standard approach, where reserve networks are delineated subject to an area constraint, ignoring differences in costs across sites. This paper is among the first to use spatially explicit models of production functions for ecosystem services in an optimization framework for prioritizing sites for wetlands restoration. Tradeoffs between two classes of environmental benefits from wetlands restoration, habitat, and water quality were assessed in the Central Valley of California. Habitat benefits were estimated by a count regression model that relates breeding mallard abundances to the configuration of land use types in the study area, and water quality benefits were estimated by a spatially distributed model of nonpoint source pollution and nutrient attenuation in wetlands. Two decision scenarios were analyzed. In the first scenario the optimal configuration of restoration activity was determined for a small watershed, and in the second scenario sites were selected from those offered for enrollment in an easement program throughout the valley. The results reveal the potential for gains in effectiveness from spatial targeting, and they suggest that there will be substantial tradeoffs between environmental benefits. Maximizing habitat quality in the small watershed yielded a 34% increase in mallard abundance and a 3% decrease in nitrogen loads to the river. In contrast, maximizing water quality resulted in a 25% decrease in nitrogen loads and a 2% increase in mallard abundance. Qualitatively similar results were obtained when sites were selected from a set of offered sites throughout the valley, but the tradeoffs were not as severe. The results also suggest that at traditional funding levels the Wetlands Reserve Program in California could reduce nitrogen loads to rivers by approximately 29,000 kg and increase total mallard abundance in the breeding season by approximately 150 individuals throughout the Central Valley in a given year.Resource /Energy Economics and Policy,

    MARKETING FINANCIAL PRODUCTS WITHIN THE ACTIVITY OF INVESTMENT BANKS

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    A production system which produces a large number of items in many steps can be modelled as a continuous flow problem. The resulting hyperbolic partial differential equation (PDE) typically is nonlinear and nonlocal, modeling a factory whose cycle time depends nonlinearly on the work in progress. One of the few ways to influence the output of such a factory is by adjusting the start rate in a time dependent manner.We study two prototypical control problems for this case: i) demand tracking where we determine the start rate that generates an output rate which optimally tracks a given time dependent demand rate and ii) backlog tracking which optimally tracks the cumulative demand. The method is based on the formal adjoint method for constrained optimization, incorporating the hyperbolic PDE as a constraint of a nonlinear optimization problem. We show numerical results on optimal start rate profiles for steps in the demand rate and for periodically varying demand rates and discuss the influence of the nonlinearity of the cycle time on the limits of the reactivity of the production system. Differences between perishable and non-perishable demand (demand vs. backlog tracking) are highlighted

    Flexible Conservation Measures on Working Land: What Challenges Lie Ahead?

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    From 1985 to 2002, most Federal conservation dollars going to farm operators have been to retire land from crop production. Yet most U.S. farmland (850 million acres) remains in active production. The Farm Security and Rural Investment (FSRI) Act of 2002 sharply increased conservation funding and earmarked most of the increase for working-land payment programs (WLPPs). The design and implementation of WLPPs will largely determine the extent to which environmental goals are achieved and whether they are cost effective. We simulate potential environmental gains as well as adjustments in agricultural production, price, and income associated with various WLPP features to illustrate tradeoffs arising from WLPP design and implementation. Competitive bidding with the use of environmental indices to rank producers for enrollment is most cost effective. Payments based on past conservation will help support farm incomes, but limit the amount of additional environmental benefit that can be generated under a fixed budget.Land Economics/Use,

    The influence of light attenuation on the biogeomorphology of a marine karst cave: a case study of Puerto Princesa Underground River, Palawan, the Philippines

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    Karst caves are unique biogeomorphological systems. Cave walls offer habitat for microorganisms which in-turn have a geomorphological role via their involvement in rock weathering, erosion and mineralisation. The attenuation of light with distance into caves is known to affect ecology, but the implications of this for biogeomorphological processes and forms have seldom been examined. Here we describe a semi-quantitative microscopy study comparing the extent, structure, and thickness of biocover and depth of endolithic penetration for samples of rock from the Puerto Princesa Underground River system in Palawan, the Philippines, which is a natural UNESCO World Heritage Site. Organic growth at the entrance of the cave was abundant (100% occurrence) and complex, dominated by phototrophic organisms (green microalgae, diatoms, cyanobacteria, mosses and lichens). Thickness of this layer was 0.28 ± 0.18 mm with active endolith penetration into the limestone (mean depth = 0.13 ± 0.03 mm). In contrast, phototrophs were rare 50 m into the cave and biofilm cover was significantly thinner (0.01 ± 0.01 mm, p < 0.000) and spatially patchy (33% occurrence). Endolithic penetration here was also shallower (< 0.01 mm, p < 0.000) and non-uniform. Biofilm was found 250 m into the cave, but with a complete absence of phototrophs and no evidence of endolithic bioerosion. We attribute these findings to light-induced stress gradients, showing that the influence of light on phototroph abundance has knock-on consequences for the development of limestone morphological features. In marine caves this includes notches, which were most well-developed at the sheltered cave entrance of our study site, and for which variability in formation rates between locations is currently poorly understood

    Panleucopenia felina : una revisión

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    En este trabajo se realiza una revisión bibliográfica sobre la panleucopenia del gato, Se describe la etiología, patogenia, cuadro clínico, tratamiento y profilaxis, Se discuten en profundidad el mecanismo patogénico y las diferentes pautas vacunales.This paper concerns a bibliographic revision on panleukopaenia in the cat. The aetiology, pathogeny, clinical picture, treatrnent and propbylaxis are described Details of the pathogenic mechanism and diverse vaccination are discussed

    Insulinoma : a propósito de un caso clínico

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    Se describe un caso de insulinoma en un perro. La presentación clínica inicial, algo oscura, permite realizar un protocolo diagnóstico diferencial primero del síndrome de debilidad, luego de hipoglucemia, y finalmente confirmar el insulinoma por las correspondientes pruebas endocrinológicas, incluido el test de la fructosamina, y visualización de nódulos característicos en páncreas gracias a la exploración ecográfica.A case of insulinoma in the dog is described. Due to the initially unclear clinical picture, a differential diagnosis of weakness is carried out at first, of hypoglycemia later, and after the endocrinologycal tests (including the fructosamine test) and ultrasonographic examination (visualizing characteristic pancreatic nodules) a final diagnosis of insulinoma is made

    Comparative analysis of the Mexican and Turkish currency crises

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    Author's OriginalThe study aims to explore characteristics of currency crises in emerging markets. Two recent experiences in Mexico and Turkey respectively analyzed carefully to identify common elements in the development and eruption of the crises. Results of the study suggest that there are several background factors and triggers that were consistent in both cases. Finally a discussion of the policy implications of the findings concludes the study.Aybar, C., Ajami, R., & Bear, M. (2000). Currency crises in emerging markets: A comparative analysis of the Mexican and Turkish cases. International Journal of Public Administration, 23(5-8), 963-1006

    First ice core records of NO3− stable isotopes from Lomonosovfonna, Svalbard

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    Samples from two ice cores drilled at Lomonosovfonna, Svalbard, covering the period 1957–2009, and 1650–1995, respectively, were analyzed for NO3− concentrations, and NO3− stable isotopes (δ15N and δ18O). Post-1950 δ15N has an average of (−6.9 ± 1.9) ‰, which is lower than the isotopic signal known for Summit, Greenland, but agrees with values observed in recent Svalbard snow and aerosol. Pre-1900 δ15N has an average of (4.2 ± 1.6) ‰ suggesting that natural sources, enriched in the 15 N-isotope, dominated before industrialization. The post-1950 δ18O average of (75.1 ± 4.1) ‰ agrees with data from low and polar latitudes, suggesting similar atmospheric NOy (NOy = NO + NO2 + HNO3) processing pathways. The combination of anthropogenic source δ15N and transport isotope effect was estimated as −29.1 ‰ for the last 60 years. This value is below the usual range of NOx (NOx = NO + NO2) anthropogenic sources which is likely the result of a transport isotope effect of –32 ‰. We suggest that the δ15N recorded at Lomonosovfonna is influenced mainly by fossil fuel combustion, soil emissions and forest fires; the first and second being responsible for the marked decrease in δ15N observed in the post-1950s record with soil emissions being associated to the decreasing trend in δ15N observed up to present time, and the third being responsible for the sharp increase of δ15N around 2000

    Future perspectives of PoseidOn stratification for clinical practice and research

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    A total of 50% of patients undergoing IVF treatment has previously been estimated to fulfill the POSEIDON classification criteria; importantly, although the reproductive prognosis differs between patients, POSEIDON patients share the same characteristic of a low ovarian response to exogenous gonadotropin stimulation\u2014independent of age. POSEIDON patients require focused attention as regards ovarian stimulation in order to increase the chances of having at least one euploid blastocyst for transfer\u2014the success criterion for stimulation set forth by the POSEIDON Group. The key to success seems to be individualization in all steps of treatment. In this perspective article we discuss the future impact of the POSEIDON stratification for daily clinical practice as well as for research
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