3,276 research outputs found
The Complex X-ray Spectrum of the Sefyert 1.5 Source NGC 6860
The X-ray spectrum of the Seyfert 1.5 source NGC 6860 is among the most
complex of the sources detected in the Swift Burst Alert Telescope all-sky
survey. A short XMM-Newton follow-up observation of the source revealed a flat
spectrum both above and below 2 keV. To uncover the complexity of the source,
in this paper we analyze both a 40 ks Suzaku and a 100 ks XMM-Newton
observation of NGC 6860. While the spectral state of the source changed between
the newer observations presented here and the earlier short XMM-Newton spectrum
- showing a higher flux and steeper power law component - the spectrum of NGC
6860 is still complex with clearly detected warm absorption signatures. We find
that a two component warm ionized absorber is present in the soft spectrum,
with column densities of about 10^20 and 10^21 cm$^-2, ionization parameters of
xi = 180 and 45 ergs cm s^-1, and outflow velocities for each component in the
range of 0-300 km s^-1. Additionally, in the hard spectrum we find a broad
(approx 11000 km s^-1) Fe K-alpha emission line, redshifted by approx 2800 km
s^-1.Comment: 35 pages, 9 figures, Accepted to Ap
Macroeconomic Adjustment and Foreign Trade of Centrally Planned Economies
This empirical study stresses the underlying macroeconomic forces which determine foreign trade flows in CPEs. The general specification includes a planners' demand equation for the volume of imports, a planners' supply equation for the volume of exports, and a rest-of-world demand equation for the export price level. The planners' behavioural equations include variables for activity levels, trade balance constraints, prices, and domestic excess demand. The import price is exogenous. This simultaneous equation model is estimated on annual data from the mid-1950s to the mid-1970s, for Czechoslovakia, the GDR, Hungary, and Poland. Maximum likelihood estimation in a nested hypothesis testing framework allows selection of restricted versions of the general model for each country. Estimated price elasticities accord with the underlying theory, and the excess demand variables perform well.
On the reversible extraction of classical information from a quantum source
Consider a source E of pure quantum states with von Neumann entropy S. By the
quantum source coding theorem, arbitrarily long strings of signals may be
encoded asymptotically into S qubits/signal (the Schumacher limit) in such a
way that entire strings may be recovered with arbitrarily high fidelity.
Suppose that classical storage is free while quantum storage is expensive and
suppose that the states of E do not fall into two or more orthogonal subspaces.
We show that if E can be compressed with arbitrarily high fidelity into A
qubits/signal plus any amount of auxiliary classical storage then A must still
be at least as large as the Schumacher limit S of E. Thus no part of the
quantum information content of E can be faithfully replaced by classical
information. If the states do fall into orthogonal subspaces then A may be less
than S, but only by an amount not exceeding the amount of classical information
specifying the subspace for a signal from the source.Comment: 22 pages, Latex2e, journal versio
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Vertical Integration and Dis-integration of Computer Firms: A History Friendly Model of the Co-evolution of the Computer and Semiconductor Industries
In this paper we present a history-friendly model of the changing vertical scope of computer firms during the evolution of the computer and semiconductor industries. The model is "history friendly", in that it attempts at replicating some basic, stylized qualitative features of the evolution of vertical integration on the basis of the causal mechanisms and processes which we believe can explain the history. The specific question addressed in the model is set in the context of dynamic and uncertain technological and market environments, characterized by periods of technological revolutions punctuating periods of relative technological stability and smooth technical progress. The model illustrates how the patterns of vertical integration and specialization in the computer industry change as a function of the evolving levels and distribution of firms' capabilities over time and how they depend on the co-evolution of the upstream and downstream sectors. Specific conditions in each of these markets - the size of the external market, the magnitude of the technological discontinuities, the lock-in effects in demand - exert critical effects and feedbacks on market structure and on the vertical scope of firms as time goes by
Structure of states which satisfy strong subadditivity of quantum entropy with equality
We give an explicit characterisation of the quantum states which saturate the
strong subadditivity inequality for the von Neumann entropy. By combining a
result of Petz characterising the equality case for the monotonicity of
relative entropy with a recent theorem by Koashi and Imoto, we show that such
states will have the form of a so-called short quantum Markov chain, which in
turn implies that two of the systems are independent conditioned on the third,
in a physically meaningful sense. This characterisation simultaneously
generalises known necessary and sufficient entropic conditions for quantum
error correction as well as the conditions for the achievability of the Holevo
bound on accessible information.Comment: 9 pages, revtex4. v2 corrects/adds some references and has a bit more
discussio
Romantic Love as a Spiritual Companionship? A Buddhist Re-Reading of George Eliot
Introduction
Like most of George Eliot\u27s fiction, Daniel Deronda can be read as a story about the possibility of redemption. Gwendolen Harleth\u27 s vanity and ambition make her vulnerable to Grandcourt\u27 s desire for dominance, and their marriage is a disaster. Belatedly, Gwendolen comes to recognise that a marriage to Daniel Deronda instead of Grandcourt might have rescued her from her egotism and led to her moral and emotional salvation. But for Deronda finding a wife is part of exploring a wider social and spiritual significance for his existence - i.e. his Jewish cultural origin and the Zionist religious, historical, and political obligations he feels this entails. This stance towards his own life gives him a level of self-understanding that enables him to seek Mirah (who shares his general life aims) as his wife while responding to Gwendolen\u27s advances with supportive compassion. On the day of Deronda\u27s wedding to Mirah, he receives the following letter from Gwendolen:
Do not think of me sorrowfully on your wedding day. I have remembered your words - that I may live to be one of the best of women, who make others glad that they were born. I do not yet see how that can be, but you know better than I. If ever it comes true, it will be because you helped me ... You must not grieve any more for me. It is better - it shall be better with me because I have known you.
This is from the last pages of George Eliot\u27s published fiction. But whereas the study of Gwendolen\u27s downfall has been generally recognised as a masterpiece, the portrayal of Deronda as a redemptive hero has been greeted by many, if not most critics with scepticism. Leavis, writing in 1946, called it \u27unrealistic\u27, excessively \u27emotional\u27, and a failure of \u27creativity\u27 and \u27intelligence\u27. More analytically, in the 1990s, the problem of Deronda\u27s supposed implausibility has been related to the general failure of realism as a genre3 and to the failure of the ethic of universal sympathy: And in 1997 Rosemary Ashton is still \u27puzzled\u27: \u27Why does an agnostic ... set out without irony a religious ideal? Moreover, is the history of Judaism any less fraught with superstition, narrowness, exclusiveness than that of Christianity?\u27
This dichotomous response - admiration for George Eliot\u27s \u27realist\u27 observation of human weakness and disdain for her \u27idealistic\u27 fables of redemption - is not, of course, limited to Daniel Deronda. Henry James complained that all George Eliot\u27s novels are \u27moralized fables\u27 and are \u27only indirectly the products of observation\u27 and Leavis agrees with James that the moralized fable \u27gives us the unsatisfactory half\u27 of George Eliot.\u27 Consequently, for Leavis, not only is Daniel Deronda \u27a prig\u27 but Adam Bede\u27s love for Dinah is \u27merely charming\u27, Rufus Lyon is \u27a bore\u27, and the characterization of Maggie Tulliver is \u27immature\u27.8 And in 1982 Barbara Hardy writes of \u27the discontent which modem readers have felt with the complacency or simplicity of the idealistic strain\u27 in all her novels
NLO QCD corrections to W+ W- b anti-b production with leptonic decays in the light of top quark mass and asymmetry measurements
We present the NLO QCD corrections to the processes p p and p anti-p to W+ W-
b anti-b including leptonic decays of the W bosons. Non-resonant contributions
as well as diagrams with doubly resonant and singly resonant top quark
propagators are fully taken into account. We employ the narrow width
approximation to perform the decays of the W bosons; spin correlations are
however preserved. We also calculate observables relevant for top quark mass
measurements, and study the impact of kinematical requirements and different
scale choices on t anti-t asymmetries.Comment: 29 pages, 14 figures, version submitted to and accepted by JHE
Appropriating the Returns from Industrial Research and Development
macroeconomics, industrial research and development, patent law
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