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Paolo Bertozzini Roberto Conti Roberto Longo 《Communications in Mathematical Physics》1998,193(2):471-492
Let ? be a local conformal net of von Neumann algebras on S
1 and ρ a M?bius covariant representation of ?, possibly with infinite dimension. If ρ has finite index, ρ has automatically
positive energy. If ρ has infinite index, we show the spectrum of the energy always to contain the positive real line, but,
as seen by an example, it may contain negative values. We then consider nets with Haag duality on ℝ, or equivalently sectors
with non-solitonic extension to the dual net; we give a criterion for irreducible sectors to have positive energy, namely
this is the case iff there exists an unbounded M?bius covariant left inverse. As a consequence the class of sectors with positive
energy is stable under composition, conjugation and direct integral decomposition.
Received: 21 April 1997 / Accepted: 23 September 1997 相似文献
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3-Hydroxy-4-hydroxymethyl pyrrolidin-2-ones, easily prepared from the Baylis–Hillman adduct 1-ethyl-4-methyl-2-hydroxy-3-methylenebutanedioate, are useful intermediates in the synthesis of bioactive compounds. In order to understand the mechanism involved in this reaction, vibrational and Montecarlo molecular mechanics conformational analysis on 1-ethyl-4-methyl-2-hydroxy-3-methylenebutanedioate were carried out, confirming the existence of a low energy intramolecular H-bonded five-member ring. 相似文献
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Telecommunications systems have recently undergone significant innovations. These call for suitable statistical models that can properly describe the behaviour of the input traffic in a network. Here we use fractional Brownian motion (FBM) to model cumulative traffic network, thus taking into account the possible presence of long‐range dependence in the data. A Bayesian approach is devised in such a way that we are able to: (a) estimate the Hurst parameter H of the FBM; (b) estimate the overflow probability which is a parameter measuring the quality of service of a network: (c) develop a test for comparing the null hypothesis of long‐range dependence in the data versus the alternative of short‐range dependence. In order to achieve these inferential results, we elaborate an MCMC sampling scheme whose output enables us to obtain an approximation of the quantities of interest. An application to three real datasets, corresponding to three different levels of traffic, is finally considered. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Monica L. Smith 《Complexity》2007,12(4):28-35
When depicted on maps as homogenous territorial wholes, ancient states are visually summarized as static entities in a way that conceals the highly fluid dynamics of polity formation, maintenance, and growth. Models derived from studies of animal behavior show that “territory” does not consist of an undifferentiated use of the landscape. Instead, the concept of territory can be parsed into a series of resource‐rich nodes linked by corridors of access, surrounded by unutilized regions and boundaries marked at points of competition. Ancient human groups also can be analyzed as having perceived and occupied landscapes through strategies of flexible networks in which nodes and corridors were surrounded by unutilized spaces around which boundaries were selectively identified and defended. This strategy is identifiable in human social groups at different levels of complexity ranging from hunter‐gatherers through ancient chiefdoms and states. © 2007 Wiley Periodicals, Inc. Complexity 12: 28–35, 2007 相似文献
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Monica Sorescu L Diamandescu D Tarabasanu-Mihaila 《Journal of Physics and Chemistry of Solids》2004,65(10):1719-1725
α-Fe2O3-In2O3 mixed oxide nanoparticles system has been synthesized by hydrothermal supercritical and postannealing route, starting with (1−x)Fe(NO3)3·9H2O·xIn(NO3)3·5H2O aqueous solution (x=0-1). X-ray diffraction and Mössbauer spectroscopy have been used to study the phase structure and substitutions in the nanosized samples. The concentration regions for the existence of the solid solutions in the α-Fe2O3-In2O3 nanoparticle system together with the solubility limits of In3+ ions in the hematite lattice and of Fe3+ ions in the cubic In2O3 structure have been evidenced. In general, the substitution level is considerably lower than the nominal concentration x. A justification of the processes leading to the formation of iron and indium phases in the investigated supercritical hydrothermal system has been given. 相似文献