5,426 research outputs found

    The durable internet: preserving network neutrality without regulation

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    An important reason for the Internet\u27s remarkable growth over the last quarter century is the "end-to-end" principle that networks should confine themselves to transmitting generic packets without worrying about their contents. Not only has this made deployment of internet infrastructure cheap and efficient, but it has created fertile ground for entrepreneurship. On a network that respects the end-to-end principle, prior approval from network owners is not needed to launch new applications, services, or content. In recent years, self-styled "network neutrality" activists have pushed for legislation to prevent network owners from undermining the end-to end principle. Although the concern is understandable, such legislation would be premature. Physical ownership of internet infrastructure does not translate into a practical ability to control its use. Regulations are unnecessary because even in the absence of robust broadband competition, network owners are likely to find deviations from the end-to-end principle unprofitable

    Scaling the Patent System

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    Why do firms in some industries ignore patents when developing new products? This paper posits a simple but novel answer to this long-puzzling question: firms ignore patents because they are unable to discover the patents their activities might infringe. The costs of finding relevant patents, which we call discovery costs, are prohibitively high. Not all industries face high patent discovery costs. Chemical patents are indexable, meaning that relevant patents can be efficiently retrieved by chemical formula. As a result, discovery costs in the chemical and pharmaceutical industries are low, and inadvertent infringement by firms in these industries is rare. But many other patent categories are not indexable, and in some cases that makes avoiding infringement practically impossible. In software, for example, patent clearance by all firms would require many times more hours of legal research than all patent lawyers in the United States can bill in a year. The result has been an explosion of patent litigation. This paper attacks two core premises of patent law — that parties are always able to respect each other’s patent rights, and that firms should be punished for infringement even if they could not have avoided it. It concludes with several suggestions for how to change the patent system to alleviate the problems created by non-indexable patents

    UK Political Cycle and the Effect on National House Prices: An Exploratory Study

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    Over the last two decades, many developed countries have experienced notable changes in house prices. This exploratory study considers if house price movements in the UK can be linked to the political cycle as governments realise homeowners represent a large portion of the voter base and their voting decisions could be influenced by the magnitude and direction of house price changes. Specifically, the paper investigates whether house prices behave differently before and after elections and under different political regimes. To examine this relationship, the study analyzed quarterly UK national house price data since 1960, along with data on the results of UK parliamentary elections during the same period. Over this period, real UK house prices increased by an average of 2.84% per annum. While there is no evidence that house prices in the UK behave significantly differently under different political parties, it is evident that house prices perform much better in the last year before an election, compared to the first year after an election. Over the time period defined for this study, house prices increased by 5.3% per annum on the average in the last year before an election compared to 1.3% per annum in the first year following an election. As this research clearly identifies major variations in house price performance around election times, residential property investment decisions should take into consideration the political cycle

    Observations of X-rays and Thermal Dust Emission from the Supernova Remnant Kes 75

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    We present Spitzer Space Telescope and Chandra X-ray Observatory observations of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the detected flux at 24 microns and hot gas parameters from fitting spectra from new, deep X-ray observations to constrain models of dust emission, obtaining a dust-to-gas mass ratio M_dust/M_gas ~0.001. We find that a two-component thermal model, nominally representing shocked swept-up interstellar or circumstellar material and reverse-shocked ejecta, adequately fits the X-ray spectrum, albeit with somewhat high implied densities for both components. We surmise that this model implies a Wolf-Rayet progenitor for the remnant. We also present infrared flux upper limits for the central pulsar wind nebula.Comment: 7 pages, 2 tables, 4 figures, uses emulateapj. Accepted for publication in Ap

    Ocean acoustical ray-tracing : Software Ray

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    A new computer program for accurate calculation of acoustic ray paths through a range-varing ocean sound channel has been written. It is based on creating a model of the speed of sound in the ocean, consistent with input data, that produces the smoothest possible wavefronts. This scheme eliminates "false caustics" from the wavefront. It may be useful in calculating an approximate solution to the full wave equation at megameter ranges.Funding was provided by the Office of Naval Research under contract N00014-86-C-0358 and the Office of Naval Technology under contract N00014-90-C-0098

    Effect of interleukin-6 receptor blockade on surrogates of vascular risk in rheumatoid arthritis: MEASURE, a randomised, placebo-controlled study

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    Objectives The interleukin-6 receptor (IL-6R) blocker tocilizumab (TCZ) reduces inflammatory disease activity in rheumatoid arthritis (RA) but elevates lipid concentrations in some patients. We aimed to characterise the impact of IL-6R inhibition on established and novel risk factors in active RA. Methods Randomised, multicentre, two-part, phase III trial (24-week double-blind, 80-week open-label), MEASURE, evaluated lipid and lipoprotein levels, high-density lipoprotein (HDL) particle composition, markers of coagulation, thrombosis and vascular function by pulse wave velocity (PWV) in 132 patients with RA who received TCZ or placebo. Results Median total-cholesterol, low-density lipoprotein-cholesterol (LDL-C) and triglyceride levels increased in TCZ versus placebo recipients by week 12 (12.6% vs 1.7%, 28.1% vs 2.2%, 10.6% vs −1.9%, respectively; all p&#60;0.01). There were no significant differences in mean small LDL, mean oxidised LDL or total HDL-C concentrations. However, HDL-associated serum amyloid A content decreased in TCZ recipients. TCZ also induced reductions (&#60;30%) in secretory phospholipase A2-IIA, lipoprotein(a), fibrinogen and D-dimers and elevation of paraoxonase (all p&#60;0.0001 vs placebo). The ApoB/ApoA1 ratio remained stable over time in both groups. PWV decreases were greater with placebo than TCZ at 12 weeks (adjusted mean difference 0.79 m/s (95% CI 0.22 to 1.35; p=0.0067)). Conclusions These data provide the first detailed evidence for the modulation of lipoprotein particles and other surrogates of vascular risk with IL-6R inhibition. When compared with placebo, TCZ induced elevations in LDL-C but altered HDL particles towards an anti-inflammatory composition and favourably modified most, but not all, measured vascular risk surrogates. The net effect of such changes for cardiovascular risk requires determination.</p

    Near-Infrared Spectroscopy of Carbon-Enhanced Metal-Poor Stars. I. A SOAR/OSIRIS Pilot Study

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    We report on an abundance analysis for a pilot study of seven Carbon-Enhanced Metal-Poor (CEMP) stars, based on medium-resolution optical and near-infrared spectroscopy. The optical spectra are used to estimate [Fe/H], [C/Fe], [N/Fe], and [Ba/Fe] for our program stars. The near-infrared spectra, obtained during a limited early science run with the new SOAR 4.1m telescope and the Ohio State Infrared Imager and Spectrograph (OSIRIS), are used to obtain estimates of [O/Fe] and 12C/13C. The chemical abundances of CEMP stars are of importance for understanding the origin of CNO in the early Galaxy, as well as for placing constraints on the operation of the astrophysical s-process in very low-metallicity Asymptotic Giant Branch (AGB) stars. This pilot study includes a few stars with previously measured [Fe/H], [C/Fe], [N/Fe],[O/Fe], 12C/13C, and [Ba/Fe], based on high-resolution optical spectra obtained with large-aperture telescopes. Our analysis demonstrates that we are able to achieve reasonably accurate determinations of these quantities for CEMP stars from moderate-resolution optical and near-infrared spectra. This opens the pathway for the study of significantly larger samples of CEMP stars in the near future. Furthermore, the ability to measure [Ba/Fe] for (at least the cooler) CEMP stars should enable one to separate stars that are likely to be associated with s-process enhancements (the CEMP-s stars) from those that do not exhibit neutron-capture enhancements (the CEMP-no stars).Comment: 27 pages, including 5 tables, 6 figures, accepted for publication in The Astronomical Journa

    Compact nano-void spectrometer based on a stable engineered scattering system

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    Random scattering of light in disordered media can be used for highly-sensitive speckle-based wavemeters and spectrometers. However, the multiple scattering events that fold long optical paths within a compact space also make such devices exceedingly sensitive to vibrations and small disturbances to the disordered media. Here, we show how scattering can be engineered so that it can be used for a compact computational spectrometer that is largely insensitive to environmental factors. We designed and fabricated a three-dimensional pseudo-random nano-void pattern with 62% scattering efficiency. The controlled amount of multiple scattering ensured a sufficiently long optical path for the target resolution of 100 pm, with optimal long-term stability. The 200 μm-thick scattering silica substrate was integrated in a compact assembly with a low-cost camera sensor. The target resolution was achieved for full spectrum measurements while single wavelengths could be determined with 50 pm resolution. Such tailored scatterers can improve the trade-off between cost, size, stability, and spectral resolution in computational spectrometers
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