13,280 research outputs found

    Governance of Dual-Use Technologies: Theory and Practice

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    The term dual-use characterizes technologies that can have both military and civilian applications. What is the state of current efforts to control the spread of these powerful technologies—nuclear, biological, cyber—that can simultaneously advance social and economic well-being and also be harnessed for hostile purposes? What have previous efforts to govern, for example, nuclear and biological weapons taught us about the potential for the control of these dual-use technologies? What are the implications for governance when the range of actors who could cause harm with these technologies include not just national governments but also non-state actors like terrorists? These are some of the questions addressed by Governance of Dual-Use Technologies: Theory and Practice, the new publication released today by the Global Nuclear Future Initiative of the American Academy of Arts and Sciences. The publication's editor is Elisa D. Harris, Senior Research Scholar, Center for International Security Studies, University of Maryland School of Public Affairs. Governance of Dual-Use Technologies examines the similarities and differences between the strategies used for the control of nuclear technologies and those proposed for biotechnology and information technology. The publication makes clear the challenges concomitant with dual-use governance. For example, general agreement exists internationally on the need to restrict access to technologies enabling the development of nuclear weapons. However, no similar consensus exists in the bio and information technology domains. The publication also explores the limitations of military measures like deterrence, defense, and reprisal in preventing globally available biological and information technologies from being misused. Some of the other questions explored by the publication include: What types of governance measures for these dual-use technologies have already been adopted? What objectives have those measures sought to achieve? How have the technical characteristics of the technology affected governance prospects? What have been the primary obstacles to effective governance, and what gaps exist in the current governance regime? Are further governance measures feasible? In addition to a preface from Global Nuclear Future Initiative Co-Director Robert Rosner (University of Chicago) and an introduction and conclusion from Elisa Harris, Governance of Dual-Use Technologiesincludes:On the Regulation of Dual-Use Nuclear Technology by James M. Acton (Carnegie Endowment for International Peace)Dual-Use Threats: The Case of Biotechnology by Elisa D. Harris (University of Maryland)Governance of Information Technology and Cyber Weapons by Herbert Lin (Stanford University

    How Tax Credits Have Affected the Rehabilitation of the Boston Office Market

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    This paper is concerned with the extent to which rehabilitation tax credits affect the conditional probability of commercial real estate rehabilitation. Very little has been written about the rehabilitation tax credit, despite the fact that it has been a feature of the U.S. tax code since 1978. Our analysis suggests that rehabilitation tax credits have been a significant determinant of the conditional probability of rehabilitation in the Boston office market. We also find that a significant portion of rehabilitation tax-credit investment is investment that would have been invested elsewhere, about 60 to 65 percent in certain periods, but rising to as high as 90 percent in other periods. We find that the rehabilitation tax credit has a significant and substantial influence on the conditional probability of rehabilitation. We also find that the greatest amount of slippage, not too surprisingly, generally occurs when the tax credit is low and when the gain from rehabilitation before the tax credit is high.

    A logarithmic generalization of tensor product theory for modules for a vertex operator algebra

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    We describe a logarithmic tensor product theory for certain module categories for a ``conformal vertex algebra.'' In this theory, which is a natural, although intricate, generalization of earlier work of Huang and Lepowsky, we do not require the module categories to be semisimple, and we accommodate modules with generalized weight spaces. The corresponding intertwining operators contain logarithms of the variables.Comment: 39 pages. Misprints corrected. Final versio

    HST NICMOS imaging of z~2, 24 micron-selected Ultraluminous Infrared Galaxies

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    We present Hubble Space Telescope NICMOS H-band imaging of 33 Ultraluminous Infrared Galaxies (ULIRGs) at z~2 that were selected from the 24 micron catalog of the Spitzer Extragalactic First Look Survey. The images reveal that at least 17 of the 33 objects are associated with interactions. Up to one fifth of the sources in our sample could be minor mergers whereas only 2 systems are merging binaries with luminosity ratio <=3:1, which is characteristic of local ULIRGs. The rest-frame optical luminosities of the sources are of the order 10^10-10^11 L_sun and their effective radii range from 1.4 to 4.9 kpc. The most compact sources are either those with a strong active nucleus continuum or those with a heavy obscuration in the mid-infrared regime, as determined from Spitzer Infra-Red Spectrograph data. The luminosity of the 7.7 micron feature produced by polycyclic aromatic hydrocarbon molecules varies significantly among compact systems whereas it is typically large for extended systems. A bulge-to-disk decomposition performed for the 6 brightest (m_H<20) sources in our sample indicates that they are best fit by disk-like profiles with small or negligible bulges, unlike the bulge-dominated remnants of local ULIRGs. Our results provide evidence that the interactions associated with ultraluminous infrared activity at z~2 can differ from those at z~0.Comment: ApJ, in press. Document revised to match the journal versio

    The FLASHES Survey I: Integral Field Spectroscopy of the CGM around 48 z=2.33.1z=2.3-3.1 QSOs

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    We present the pilot study component of the Fluorescent Lyman-Alpha Structures in High-z Environments (FLASHES) Survey; the largest integral-field spectroscopy survey to date of the circumgalactic medium at z=2.33.1z=2.3-3.1. We observed 48 quasar fields between 2015 and 2018 with the Palomar Cosmic Web Imager (Matuszewski et al. 2010). Extended HI Lyman-α\mathrm{\alpha} emission is discovered around 42/48 of the observed quasars, ranging in projected, flux-weighted radius from 21-71 proper kiloparsecs (pkpc), with 26 nebulae exceeding 100 pkpc100\mathrm{~pkpc} in effective diameter. The circularly averaged surface brightness radial profile peaks at a maximum of 1×1017 erg s1 cm2 arcsec2\mathrm{1\times 10^{-17}~erg~s^{-1}~cm^{-2}~arcsec^{-2}} (2×1015 erg s1 cm2 arcsec22\times10^{-15}~\mathrm{erg~s^{-1}~cm^{-2}~arcsec^{-2}} adjusted for cosmological dimming) and luminosities range from 1.9×1043 erg s11.9\times10^{43}~\mathrm{erg~s^{-1}} to 14.1×1043 erg s1-14.1\times10^{43}~\mathrm{erg~s^{-1}}. The emission appears to have a highly eccentric morphology and a maximum covering factor of 50%50\% (60%60\% for giant nebulae). On average, the nebular spectra are red-shifted with respect to both the systemic redshift and Lyα\alpha peak of the quasar spectrum. The integrated spectra of the nebulae mostly have single or double-peaked line shapes with global dispersions ranging from 167 km s1167~\mathrm{km~s^{-1}} to 690 km s1690~\mathrm{km~s^{-1}}, though the individual (Gaussian) components of lines with complex shapes mostly appear to have dispersions 400\leq 400 km s1\mathrm{km~s^{-1}}, and the flux-weighted velocity centroids of the lines vary by thousands of km s1 \mathrm{km~s^{-1}} with respect to the systemic QSO redshifts. Finally, the root-mean-square velocities of the nebulae are found to be consistent with gravitational motions expected in dark matter halos of mass Mh1012.5M\mathrm{M_h \simeq10^{12.5} M_\odot}. We compare these results to existing surveys at both higher and lower redshift

    Observations Supporting the Role of Magnetoconvection in Energy Supply to the Quiescent Solar Atmosphere

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    Identifying the two physical mechanisms behind the production and sustenance of the quiescent solar corona and solar wind poses two of the outstanding problems in solar physics today. We present analysis of spectroscopic observations from the Solar and Heliospheric Observatory that are consistent with a single physical mechanism being responsible for a significant portion of the heat supplied to the lower solar corona and the initial acceleration of the solar wind; the ubiquitous action of magnetoconvection-driven reprocessing and exchange reconnection of the Sun's magnetic field on the supergranular scale. We deduce that while the net magnetic flux on the scale of a supergranule controls the injection rate of mass and energy into the transition region plasma it is the global magnetic topology of the plasma that dictates whether the released ejecta provides thermal input to the quiet solar corona or becomes a tributary that feeds the solar wind.Comment: 34 pages, 13 figures - In press Astrophysical Journal (Jan 1 2007

    Do Differences in Pleadings Standards Cause Forum Shopping in Securities Class Actions?: Doctrinal and Empirical Analyses

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    Federal appellate courts have promulgated divergent legal standards for pleading fraud in securities fraud class actions after the Private Securities Litigation Reform Act (PSLRA). Recently, the Supreme Court of the United States issued a decision in Tellabs, Inc. v. Makor Issues & Rights, Ltd. that could have resolved these differences, but did not do so. This Paper provides two significant contributions. We first show that Tellabs avoids deciding the hard issues that confront courts and litigants daily in the wake of the PSLRA\u27s heightened pleading standard. As a consequence, the opinion keeps very much alive the circuits\u27 disparate interpretations of the PSLRA\u27s fraud pleading standard. To be sure, Tellabs might ultimately be applied by lower courts to narrow the range of permissible approaches to satisfying the strong inference standard, but leaves a good deal of room within which wide variations in approach will continue. Our second contribution is empirical in that we seek to answer the question: do plaintiffs\u27 attorneys take advantage of the differences among the circuits\u27 interpretation of the pleading standard to select more favorable venues to file their cases, as some scholars have claimed? We find that 85 percent of the securities fraud class actions in our sample are filed in the home circuit of the defendant corporation. While we find that the differences in the circuits\u27 pleading standards do not have a statistically significant impact on the plaintiffs\u27 choice of venue, we find that plaintiffs are more likely to file low-value cases in jurisdictions other than the one in which the defendant\u27s headquarters is located
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