78,918 research outputs found

    Charles M. Breder, Jr.: Dry Tortugas, 1929

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    During the summer of 1929, Dr. Charles M. Breder, Jr., employed at that time by the New York Aquarium and American Museum of Natural History, visited the Carnegie Laboratory in the Dry Tortugas to study the development and habits of flying fishes and their allies. The diary of the trip was donated to the Mote Marine Laboratory Library by his family. Dr. Breder's meticulous handwritten account gives us the opportunity to see the simple yet great details of his observations and field experiments. His notes reveal the findings and thoughts of one of the world's greatest ichthyologists. The diary was transcribed as part of the Coastal Estuarine Data/Document Rescue and Archeology effort for South Florida. (PDF contains 75 pages

    Beta lives - some statistical perspectives on the capital asset pricing model

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    This note summarizes some technical issues relevant to the use of the idea of excess return in empirical modelling. We cover the case where the aim is to construct a measure of expected return on an asset and a model of the CAPM type is used. We review some of the problems and show examples where the basic CAPM may be used to develop other results which relate the expected returns on assets both to the expected return on the market and other factors

    The Hedonic Price Structure of Faculty Compensation at U.S. Colleges and Universities

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    Economic theory suggests that the variation in academic salaries across institutions in part reflects compensating differences associated with variation in the levels of local quality of life factors such as environmental quality and the provision of local public services. This paper presents an econometric analysis of the hedonic, or implicit price structure, of faculty compensation at U.S. colleges and universities using data from AAUP merged with data on a host of location-specific characteristics. Quality of life factors are found to be important, accounting for between 7 percent and 12.8 percent of total compensation

    The Effective Potential And Additional Large Radius Compactified Space-Time Dimensions

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    The consequences of large radius extra space-time compactified dimensions on the four dimensional one loop effective potential are investigated for a model which includes scalar self interactions and Yukawa coupling to fermions. The Kaluza-Klein tower of states associated with the extra compact dimensions shifts the location of the effective potential minimum and modifies its curvature. The dependence of these effects on the radius of the extra dimension is illustrated for various choices of coupling constants and masses. For large radii, the consequence of twisting the fermion boundary condition on the compactified dimensions is numerically found to produce but a negligible effect on the effective potential.Comment: 14 pages, LaTeX, 6 Postscript figure

    The Akulov-Volkov Lagrangian, Symmetry Currents and Spontaneously Broken Extended Supersymmetry

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    A generalization of the Akulov-Volkov effective Lagrangian governing the self interactions of the Nambu-Goldstone fermions associated with spontaneously broken extended supersymmetry as well as their coupling to matter is presented and scrutinized. The resulting currents associated with R-symmetry, supersymmetry and space-time translations are constructed and seen to form a supermultiplet structure.Comment: 17 pages, LaTeX; Title, abstract and introduction changes, references adde

    Performance statistics of the FORTRAN 4 /H/ library for the IBM system/360

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    Test procedures and results for accuracy and timing tests of the basic IBM 360/50 FORTRAN 4 /H/ subroutine library are reported. The testing was undertaken to verify performance capability and as a prelude to providing some replacement routines of improved performance

    Risk management disclosure practices of UK non-financial firms after FRS13.

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    In the United Kingdom Financial Reporting Standard (FRS) 13, which came into force for March 1999 yearends, requires narrative and numerical disclosure of all financial instruments held or issued, in order to provide information about their impact on the firm’s risk profile. We use this information to examine the interest rate and currency profile of financial liabilities and assets. We find that UK firms on average have a greater proportion of assets and liabilities tied to floating rates of interest and that they tend to match the interest rate profile of assets and liabilities. Although sterling liabilities on average represent over half of total liabilities, for firms holding sterling and non-sterling debt the US dollar was the dominant currency. We also find a relationship between the level of foreign operations and foreign debt. Since the foreign debt profile is disclosed after the effect of derivatives, this result suggests that cross-currency swaps are used for hedging

    Ionisation-induced star formation II: External irradiation of a turbulent molecular cloud

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    In this paper, we examine numerically the difference between triggered and revealed star formation. We present Smoothed Particle Hydrodynamics (SPH) simulations of the impact on a turbulent 10^4 solar-mass molecular cloud of irradiation by an external source of ionising photons. In particular, using a control model, we investigate the triggering of star formation within the cloud. We find that, although feedback has a dramatic effect on the morphology of our model cloud, its impact on star formation is relatively minor. We show that external irradiation has both positive and negative effects, accelerating the formation of some objects, delaying the formation of others, and inducing the formation of some that would not otherwise have formed. Overall, the calculation in which feedback is included forms nearly twice as many objects over a period of \sim0.5 freefall times (\sim2.4 Myr), resulting in a star--formation efficiency approximately one third higher (\sim4% as opposed to \sim3% at this epoch) as in the control run in which feedback is absent. Unfortunately, there appear to be no observable characteristics which could be used to differentiate objects whose formation was triggered from those which were forming anyway and which were simply revealed by the effects of radiation, although this could be an effect of poor statistics.Comment: 12 pages, 9 figures, accepted by MNRA

    Helmet weight simulator

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    A device for providing acceleration cues to the helmet of a simulator pilot is described. Pulleys are attached to both shoulders of the pilot. A cable is attached to both sides of the helmet and extends through the pulleys to a takeup reel that is controlled by a torque motor. Control signals are applied to a servo system including the torque motor, the takeup reel and a force transducer which supplies the feedback signal. In one embodiment of the invention the force transducer is in the cable and in another it is in the takeup reel
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