42,608 research outputs found
[Review of] August Wilson. Fences
At the turn of the century, playwrights wrestled with realism and wrought a new theater capable of great poetic and symbolic force. It was an exciting time because artists turned their talents to subjects which had never been deemed fit for the stage. The classic requirements of rank and verse were swept aside as audiences learned that even illiterates could make music with their tongues, and that eloquent, serious exploration of the human condition extended well beyond the provinces of kings and queens
Anomalies in Economics and Finance
The term âanomalyâ played a crucial role in Thomas Kuhnâs characterization of scientific progress. For Kuhn, an anomaly is a puzzle which challenges an accepted paradigm. Puzzles only achieve anomalous status once an alternative paradigm becomes available which allows explanation of the puzzle. Anomalies were introduced into the finance literature by Michael Jensen but more as resolvable puzzles than Kuhnian anomalies. They entered economics via Richard Thaler who saw behavioural economics as the alternative to the neoclassical paradigm. Both authors use the term anomaly in a deliberately Kuhnian manner. Kuhn formulated his ideas by looking back across the history of physics. By contrast, behavioural economists use Kuhnâs concepts in a forward-looking manner as a marketing tool for their ideas.anomaly, behavioural, effects.
Commodity Speculation and Commodity Investment
I distinguish between speculation and index-based investment in commodity futures stressing the differing motivations of the two groups and the differing instruments that they use. I discuss the amounts of money deployed in these activities. I document evidence of extrapolative behaviour in metals prices, consistent with speculation affecting prices, and show that in at least one market (soybeans) index-based investment has a significant and persistent price impact.Commodities, Speculation, Asset Allocation
A 100 kW experimental wind turbine: Simulation of starting, overspeed, and shutdown characteristics
The ERDA/NASA 100 kW experimental wind turbine is modeled on a digital computer in order to study the performance of a wind turbine under operating conditions. Simulation studies of starting, overspeed, and shutdown performance were made. From these studies operating procedures, precautions, and limitations are prescribed
How to Understand High Food Prices
Commodity price booms are best explained by macroeconomic rather than market-specific factors. I argue that the rise in food prices over 2007 and the first half of 2008 should be seen as part of the wider commodity boom which is largely the result of rapid economic growth in China and throughout Asia in a context of loose money and in which, because of previous low investment, supply was inelastic. The demand for grains and oilseeds as biofuel feedstocks was the main cause of the price rise but macroeconomic and financial factors explain its extent. The futures market may be an important monetary transmission mechanism, but it is commodity investors, not speculators, who, by investing in commodities as an asset class, may have generalized prices rises across markets.Food prices, commodity prices, money, futures markets
Commonality in the LME aluminium and copper volatility processes through a Figarch lens
We consider dynamic representation of spot and three month aluminium and
copper volatilities. These are the two most important metals traded in the
London Metal Exchange (LME). They share common business cycle factors
and are traded under identical contract specifications. We apply the bivariate
FIGARCH model which allows parsimonious representation of long
memory volatility processes. Our results show that spot and three month
aluminium and copper volatilities follow long memory processes, that they
exhibit a common degree of fractional integration and that the processes are
symmetric. However, there is no evidence that the processes are fractionally
cointegrated. This high degree of commonality may result from the common
LME trading process
Kinetics of the Photoreduction of \u3cem\u3ep\u3c/em\u3e-nitrobenzoic Acid on Ag and AgxAu1-x Nanoparticle Films
A recent strategy to increase the efficiency of photovoltaic and photoemissive devices has been to include metal nanolayers in contact with an organic layer inside these devices. Metal nanoparticles (especially Ag and Au) are known to catalyze photoreactions of organic molecules on their surfaces. The reactivity of organics at nanometal surfaces has implications for device lifetimes; therefore, it is important to understand how nanoparticle size and composition influence reaction rates. The photoreduction of p-nitrobenzoate (PNBA) to p,pâ-azodibenzoate (PPADBA) on Ag nanoparticles is an excellent model system for studying such reactions. We have measured the reaction rate of PNBA to PPADBA on Ag and Au based nanoparticle surfaces using surface-enhanced Raman spectroscopy (SERS). SERS is a highly sensitive spectroscopic tool, which provides molecular fingerprints that can be used to identify molecular species present on metal nanoparticle surfaces. These surfaces are made from layers from Ag and AgxAu1-x alloy nanoparticles with diameters ranging from 50-80 nm
Design of wideband vibration-based electromagnetic generator by means of dual-resonator
This paper describes the design of a wideband electromagnetic energy harvester that utilizes a novel dual-resonator method to improve the operational frequency range of the vibration-based generator. The device consists of two separate resonator systems (coil and magnet), which each comply with their respective resonance frequencies. This is because both resonators are designed in such a way that both magnet and coil components will oscillate at an additive phase angle, and hence create greater relative motion between the two dominating resonance frequencies, which realizes the wideband generator. Each resonator system consists of a distinctive cantilever beam, one attached with four magnets and steel keepers, the other attached with a copper coil and stainless steel holder as the free end mass. Both cantilevers are clamped and fitted to a common base that is subjected to a vibration source. Basic analytical models are derived and a numerical model is implemented in MATLAB-Simulink. Electromagnetic, structural modal and static mechanical analysis for the design of the prototype are completed using ANSYS finite element tools. For a 0.8 m sâ2 acceleration, the open-loop voltage obtained from the experiment shows a good correlation with those from the simulation. Peak induced voltage is measured to be 259.5Vrms as compared to 240.9Vrms from the simulator at 21.3 Hz, which implies an error range of 7.7%. The results also indicate that there is a maximum of 58.22% improvement in the induced voltage within the intermediate region which occurs at the intersection point between the output response plots of two single resonator generators
Inviscid Flow Field Effects: Experimental results
The aero-optical distortions due to invisid flow effects over airborne laser turrets is investigated. Optical path differences across laser turret apertures are estimated from two data sources. The first is a theoretical study of main flow effects for a spherical turret assembly for a Mach number (M) of 0.6. The second source is an actual wind tunnel density field measurement on a 0.3 scale laser turret/fairing assembly, with M = 0.75. A range of azimuthal angles from 0 to 90 deg was considered, while the elevation angle was always 0 deg (i.e., in the plane of the flow). The calculated optical path differences for these two markedly different geometries are of the same order. Scaling of results to sea level conditions and an aperture diameter of 50 cm indicated up to 0.0007 cm of phase variation across the aperture for certain forward look angles and a focal length of F = -11.1 km. These values are second order for a 10.6 micron system
Globalization and International Commodity Trade with Specific Reference to the West African Cocoa Producers
Liberalization of tropical agricultural markets has brought globalization, in the sense that all producers now face world rather than domestic prices. Producer prices have tended to rise as a share of fob prices as intermediation costs and tax has declined. However, in conjunction with inelastic demand, the downward shift of the aggregate supply curve results in lower world prices. Farmers therefore get a higher share of a lower price. Cocoa is the market where these changes have been most pronounced. The incidence of the liberalization benefits in cocoa is largely on developed country consumers at the expense of the governments of the exporting countries and farmers in non-liberalizing (non-African) countries. Farmers in liberalized African markets are broadly neither better nor worse off.
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