6,505 research outputs found

    Because We Smile: Jonathan Swift\u27s Enthusiastic Magnifying Glass

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    Jonathan Swift (1667-1745) was intellectually before his time. His insights into the human condition reveal a belief in the not-hopeless corruption of humanity. To capture this state of the human condition, he used two key symbols: wind and machine. These two symbols represent the two sides of the dialectical argument into which Swift forces his readers. What guide should direct humanity-enthusiasm and emotional stimulation (wind) or reason and objective systems (the machine)? Preoccupied with these two ideas, Swift uses his scatological satires to level all of humanity. Swift forces his readers onto their knees in the mud and mire and only after moving them toward repenting of all vain pride does Swift allow his audience the redemption of laughter

    Federal Legislation to End Discrimination Against Women

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    Eigenvector Sky Subtraction

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    We develop a new method for estimating and removing the spectrum of the sky from deep spectroscopic observations; our method does not rely on simultaneous measurement of the sky spectrum with the object spectrum. The technique is based on the iterative subtraction of continuum estimates and Eigenvector sky models derived from Singular Value Decompositions (SVD) of sky spectra, and sky spectra residuals. Using simulated data derived from small telescope observations we demonstrate that the method is effective for faint objects on large telescopes. We discuss simple methods to combine our new technique with the simultaneous measurement of sky to obtain sky subtraction very near the Poisson limit.Comment: Accepted for publication in The Astrophysical Journal (Letters) 2000 March 7. Includes one extra figure which did not fit in a lette

    Merging binary black holes formed through chemically homogeneous evolution in short-period stellar binaries

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    We explore a newly proposed channel to create binary black holes of stellar origin. This scenario applies to massive, tight binaries where mixing induced by rotation and tides transports the products of hydrogen burning throughout the stellar envelopes. This slowly enriches the entire star with helium, preventing the build-up of an internal chemical gradient. The stars remain compact as they evolve nearly chemically homogeneously, eventually forming two black holes, which, we estimate, typically merge 4--11 Gyr after formation. Like other proposed channels, this evolutionary pathway suffers from significant theoretical uncertainties, but could be constrained in the near future by data from advanced ground-based gravitational-wave detectors. We perform Monte Carlo simulations of the expected merger rate over cosmic time to explore the implications and uncertainties. Our default model for this channel yields a local binary black hole merger rate of about 1010 Gpc−3^{-3} yr−1^{-1} at redshift z=0z=0, peaking at twice this rate at z=0.5z=0.5. This means that this channel is competitive, in terms of expected rates, with the conventional formation scenarios that involve a common-envelope phase during isolated binary evolution or dynamical interaction in a dense cluster. The events from this channel may be distinguished by the preference for nearly equal-mass components and high masses, with typical total masses between 50 and 110 M⊙\textrm{M}_\odot. Unlike the conventional isolated binary evolution scenario that involves shrinkage of the orbit during a common-envelope phase, short time delays are unlikely for this channel, implying that we do not expect mergers at high redshift.Comment: Minor update to match the version published in MNRAS; 15 pages 10 figure

    Quantum Key Distribution (QKD) and Commodity Security Protocols: Introduction and Integration

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    We present an overview of quantum key distribution (QKD), a secure key exchange method based on the quantum laws of physics rather than computational complexity. We also provide an overview of the two most widely used commodity security protocols, IPsec and TLS. Pursuing a key exchange model, we propose how QKD could be integrated into these security applications. For such a QKD integration we propose a support layer that provides a set of common QKD services between the QKD protocol and the security applicationsComment: 12Page

    Merger rates of double neutron stars and stellar origin black holes: The Impact of Initial Conditions on Binary Evolution Predictions

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    The initial mass function (IMF), binary fraction and distributions of binary parameters (mass ratios, separations and eccentricities) are indispensable input for simulations of stellar populations. It is often claimed that these are poorly constrained significantly affecting evolutionary predictions. Recently, dedicated observing campaigns provided new constraints on the initial conditions for massive stars. Findings include a larger close binary fraction and a stronger preference for very tight systems. We investigate the impact on the predicted merger rates of neutron stars and black holes. Despite the changes with previous assumptions, we only find an increase of less than a factor 2 (insignificant compared with evolutionary uncertainties of typically a factor 10-100). We further show that the uncertainties in the new initial binary properties do not significantly affect (within a factor of 2) our predictions of double compact object merger rates. An exception is the uncertainty in IMF (variations by a factor of 6 up and down). No significant changes in the distributions of final component masses, mass ratios, chirp masses and delay times are found. We conclude that the predictions are, for practical purposes, robust against uncertainties in the initial conditions concerning binary parameters with exception of the IMF. This eliminates an important layer of the many uncertain assumptions affecting the predictions of merger detection rates with the gravitational wave detectors aLIGO/aVirgo.Comment: Accepted for publication in Ap

    Has the Stability and Growth Pact Impeded Political Budget Cycles in the European Union?

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    This paper examines whether there is a political budget cycle (PBC) in countries in the euro area. Using a multivariate model for the period 1999-2004 and various election indicators we find strong evidence that the Stability and Growth Pact has not restricted fiscal policy makers in the euro area in pursuing expansionary policies before elections. In an election-year – but not in the year prior to the election – the budget deficit increases. This result is in line with third generation PBC models, which are based on moral hazard. We also find a significant but small partisan effect on fiscal policy outcomes.fiscal policy, political budget cycle, Stability and Growth Pact
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