4,928 research outputs found

    The JetCurry Code. I. Reconstructing Three-Dimensional Jet Geometry from Two-Dimensional images

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    We present a reconstruction of jet geometry models using numerical methods based on a Markov ChainMonte Carlo (MCMC) and limited memory Broyden-Fletcher-Goldfarb-Shanno (BFGS) optimized algorithm. Our aim is to model the three-dimensional geometry of an AGN jet using observations, which are inherently two-dimensional. Many AGN jets display complex hotspots and bends over the kiloparsec scales. The structure of these bends in the jets frame may be quite different than what we see in the sky frame, transformed by our particular viewing geometry. The knowledge of the intrinsic structure will be helpful in understanding the appearance of the magnetic field and hence emission and particle acceleration processes over the length of the jet. We present the method used, as well as a case study based on a region of the M87 jet.Comment: Submitted to ApJ on Feb 01, 201

    Products Liability Reform in Congress: An Issue of Federalism

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    High Energy Variability Of Synchrotron-Self Compton Emitting Sources: Why One Zone Models Do Not Work And How We Can Fix It

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    With the anticipated launch of GLAST, the existing X-ray telescopes, and the enhanced capabilities of the new generation of TeV telescopes, developing tools for modeling the variability of high energy sources such as blazars is becoming a high priority. We point out the serious, innate problems one zone synchrotron-self Compton models have in simulating high energy variability. We then present the first steps toward a multi zone model where non-local, time delayed Synchrotron-self Compton electron energy losses are taken into account. By introducing only one additional parameter, the length of the system, our code can simulate variability properly at Compton dominated stages, a situation typical of flaring systems. As a first application, we were able to reproduce variability similar to that observed in the case of the puzzling `orphan' TeV flares that are not accompanied by a corresponding X-ray flare.Comment: to appear in the 1st GLAST symposium proceeding

    STRATIGRAPHIC, GEOCHEMICAL, AND GEOCHRONOLOGICAL ANALYSIS OF THE WOLFCAMP-D INTERVAL, MIDLAND BASIN, TEXAS

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    Subsurface data derived from ~388 ft of drill core from Martin County (TX) were used to understand the depositional setting of the Wolfcamp-D, a petroleum producing interval in the Midland Basin. Elemental geochemistry collected via x-ray fluorescence revealed a highly variable depositional history marked by the deposition of diverse siliciclastic and carbonate lithofacies. Integration of multiple datasets resulted in the interpretation of nine lithofacies, whose deposition appears cyclical. Correlations between molybdenum and total organic carbon indicate slow recharge of bottom waters and anoxic/euxinicconditions within the basin. The presence of phosphatic nodules coinciding with siliceous black mudrocks suggested high levels of primary productivity driven by upwelling. High-frequency sea level variability, driven by far-field glaciation and regional paleoclimate, were key controls on both the chemostratigraphy and lithofacies. Along-strike variability is seen throughout the basin due to paleobathymetry, proximity and connections to paleochannels, and localized structures. Rhenium-osmium (Re/Os) geochronology was conducted on siliceous mudrocks with high total organic carbon. A depositional age of 300 ± 18 Ma was obtained, partially confirming previous correlations to shelf biostratigraphic data. Scatter in the Re/Os data is likely due to mixing in the basin or non-hydrogenous Os incorporated into the analysis due to the method of preparation

    Taking the Protection-Access Tradeoff Seriously

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    Law and economics scholarship has contributed much to our understanding of both the nature of intellectual property rights generally and the features of individual intellectual property regimes. Indeed it is hard to imagine a field other than antitrust law that is so explicitly governed by economic thinking. In authorizing the copyright and patent systems, Article I, Section 8 of the United States Constitution expressly incorporates a social welfare imperative as the basis for its grant of power.\u27 Certainly economists and economically oriented legal academics have given the field the attention it is due. I am far from being a sophisticated economic thinker, although I admire those who are and the insights they have brought to my understanding of what is at stake in intellectual property. My comments are more practical in nature. They involve the tension that arises throughout the law of intellectual property and unfair competition between protection of intellectual achievement and public access to intellectual products. This tension is reflected in the central questions: When are intellectual property rights appropriate and what is their proper scope? Economics seems to provide an apt description but an inadequate basis for answering these questions. And there lies, in my view, one of the reasons for the trend throughout intellectual property to enlarge property rights at the expense of access. For those of us who deem this trend problematic, economic analysis seems increasingly unhelpful in formulating a response protective of the public domain. The tension between protection and access pervades intellectual property and unfair competition law. The casebook Ed Kitch and I coauthored uses it as one of the themes that tie the disparate chapters of the book together. Protection or access is at issue whether the case involves a local barber who wants an exclusive property interest in the barbering business of Howard Lake, Minnesota, or the promisee of a contract who claims to have a property interest in the future performance of the promissor, or the firm that claims a property interest in the firm\u27s investment in the human capital of its workers, or the trademark owner who asserts a property right over portions of the English language, or the celebrity who seeks to capture gains from his or her celebrity status, or the more traditional cases involving constitutionally recognized authors and inventors. There should be little doubt that the trend throughout intellectual property and unfair competition is toward greater protection and diminished access. The Digital Millennium Copyright Act is a notorious example of a protectionist advance, as is the apparent willingness of the Patent and Trademark Office and the Federal Circuit to expand the realm of patent protection. But the trend is noticeable elsewhere as well. The adoption of the trademark dilution cause of action and the expanding protection against cyber-squatters have refocused trademark law away from its traditional function of prevention of consumer confusion toward one that confers substantial property rights on trademark owners. The protection of trade dress without proof of secondary meaning also favors property rights over rights of access. A similar rule applied to product designs and configurations would have created an even more damaging effect on competition, but the Supreme Court happily required proof of actual distinctiveness

    "Good to Great" in Pubic Research Universities

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