17,751 research outputs found

    Alternative instruments for smoothing the consumption of primary commodity exporters

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    Countries that depend on a single primary export for their foreign earnings are likely to experience sharp fluctuations in export earnings and their underlying wealth, because of the instability of all primary commodity markets. As part of structural adjustment, several countries have liberalized their trade regimes, so domestic producers are no longer insulated from international price fluctuations. This paper concentrates on the management of country-level consumption risk, and considers actions which the government might undertake to reduce the cost of that risk. The paper reviews the costs of export price instability, with some reference to the empirical magnitudes. It considers the role of conventional instruments, including loans, price stabilization measures, and futures contracts. Particular attention is paid to the potential use of futures rollovers for longer-term price protection, and the effect of production response on that protection. The paper also discusses"commodity bonds"and dynamic consumption smoothing paths and offers conclusions.Economic Theory&Research,Environmental Economics&Policies,Banks&Banking Reform,Access to Markets,Markets and Market Access

    The Influence of Lake Surface Temperature on Atmospheric Circulations in the Great Lakes Region.

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    Recently, media coverage of extreme weather events has come with the question “Was this storm caused by climate change?” The scientific community has started to develop statistical measures to try to answer this question, but these studies do not gain insight into the physical causes leading to the storm. This thesis will directly look at some of the physical processes within weather systems in the Laurentian Great Lakes region that could be altered in a future climate through a series of convective allowing simulations using the Weather Research and Forecasting Model (WRF). In the Laurentian Great Lakes region, located at the border of Canada and the United States, the existence of the lakes and the lake surface temperature play a key role in the weather and climate of the region. While it is projected that lake temperatures will increase in a future climate, it is still relatively unknown what this change could mean to atmospheric circulations in the region. The case studies presented look at the direct role the lake surface temperature has on these circulations during the cold and warm seasons to understand the sensitivity of these circulations to future climate conditions. For a lake-effect snowfall simulation, it is shown that the lake temperature influences the extent and intensity of the snowfall downwind of the lake, while interactions with the topography downwind of the lakes still have a critical role. Warm season simulations showed little influence from the lake temperature on precipitation amounts. However, various degrees of change were seen in atmospheric circulations, from little to no change in the convective initiation along Lake Michigan due to the passing of a potential vorticity feature, to larger changes over Lake Superior to the structure of the barrier jet and a mesoscale convective system. Collectively, these simulations show the importance of resolving the lakes in climate simulations and feedbacks that may not be resolved at lower horizontal resolutions, especially in winter. These simulations also give a baseline for future work testing the sensitivity of storm systems over the region to other components.PhDAtmospheric, Oceanic and Space SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133427/1/dmwright_1.pd

    Pupal Polymorphism of the Bog Copper Butterfly \u3ci\u3eLycaena\u3c/i\u3e (\u3ci\u3eEpidemia\u3c/i\u3e) \u3ci\u3eepixanthe\u3c/i\u3e (Bsd. & Le C. [1835]) (Lycaenidae: Lycaeninae) in New Jersey

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    The immature stages of the Bog Copper butterfly, Lycaena epixanthe, were described in detail by the author nearly forty years ago. Two different pupal colors were interpreted to represent distinct separate morphs with genetically-fixed incidences. Reassessment of the data discloses a pattern of progressive color change of each individual pupa throughout the pupal period. This transforming strategy is adaptive and may reduce predator recognition

    Egg Plastron of the Bog Copper Butterfly \u3ci\u3eTharsalea\u3c/i\u3e (\u3ci\u3eEpidemia\u3c/i\u3e) \u3ci\u3eepixanthe\u3c/i\u3e (Bsd. & Le C. [1835]) (Lycaenidae: Lycaeninae)

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    The egg of the Bog Copper butterfly, Tharsalea (Epidemia) epixanthe, has a prominent highly-sculptured chorionic surface. Trapped within the chorion is a labyrinth of air spaces which has been proposed as a plastron for gas exchange while the egg is submerged in water. Data derived from scanning electron microscopy (SEM) confirms the plastron should function as predicted. Furthermore, the insulating air spaces should prevent water loss of the diapausing first instar larvae while overwintering

    Randomized Polypill Crossover Trial in People Aged 50 and Over

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    PMCID: PMC3399742This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

    Revision of Earth-sized Kepler Planet Candidate Properties with High Resolution Imaging by Hubble Space Telescope

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    We present the results of our Hubble Space Telescope program and describe how our analysis methods were used to re-evaluate the habitability of some of the most interesting Kepler planet candidates. Our program observed 22 Kepler Object of Interest (KOI) host stars, several of which were found to be multiple star systems unresolved by Kepler. We use our high-resolution imaging to spatially resolve the stellar multiplicity of Kepler-296, KOI-2626, and KOI-3049, and develop a conversion to the Kepler photometry (Kp) from the F555W and F775W filters on WFC3/UVIS. The binary system Kepler-296 (5 planets) has a projected separation of 0.217" (80AU); KOI-2626 (1 planet candidate) is a triple star system with a projected separation of 0.201" (70AU) between the primary and secondary components and 0.161" (55AU) between the primary and tertiary; and the binary system KOI-3049 (1 planet candidate) has a projected separation of 0.464" (225AU). We use our measured photometry to fit the separated stellar components to the latest Victoria-Regina Stellar Models with synthetic photometry to conclude that the systems are coeval. The components of the three systems range from mid-K dwarf to mid-M dwarf spectral types. We solved for the planetary properties of each system analytically and via an MCMC algorithm using our independent stellar parameters. The planets range from ~1.6R_Earth to ~4.2R_Earth, mostly Super Earths and mini-Neptunes. As a result of the stellar multiplicity, some planets previously in the Habitable Zone are, in fact, not, and other planets may be habitable depending on their assumed stellar host.Comment: 16 pages, 10 figures, ApJ, 804, 9
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