612 research outputs found

    Synthesis and Recognition Properties of Higher Order Tetrathiafulvalene (Ttf) Calix N Pyrroles (N=4-6)

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    Two new benzoTTF-annulated calix[n]pyrroles (n = 5 and 6) were synthesized via a one-step acid catalyzed condensation reaction and fully characterized via single crystallographic analyses. As compared to the known tetra-TTF annulated calix[4]pyrrole, which is also produced under the conditions of the condensation reaction, the expanded calix[n]pyrroles (n = 5 and 6) are characterized by a larger cavity size and a higher number of TTF units (albeit the same empirical formula). Analysis of the binding isotherms obtained from UV-Vis spectroscopic titrations carried out in CHCl3 in the presence of both anionic (Cl-, Br-, I-, CH3COO-, H2PO4-, and HSO4-) and neutral (1,3,5-trinitrobenzene (TNB) and 2,4,6-trinitrotoluene (TNT)) substrates revealed that as a general rule the calix[6]pyrrole derivative proved to be the most efficient molecular receptor for anions, while the calix[4]pyrrole congener proves most effective for the recognition of TNB and TNT. These findings are rationalized in terms of the number of electron rich TTF subunits and NH hydrogen bond donor groups within the series, as well as an ability to adopt conformations suitable for substrate recognition, and are supported by solid state structural analyses.National Science Foundation CHE 1057904, 0741973Robert A. Welch Foundation F-1018Danish Natural Science Research Council (FNU) 272-08-0047, 11-106744WCU (World Class University) program of Korea R32-2010-10217-0Villum FoundationChemistr

    Bounded Determinization of Timed Automata with Silent Transitions

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    Deterministic timed automata are strictly less expressive than their non-deterministic counterparts, which are again less expressive than those with silent transitions. As a consequence, timed automata are in general non-determinizable. This is unfortunate since deterministic automata play a major role in model-based testing, observability and implementability. However, by bounding the length of the traces in the automaton, effective determinization becomes possible. We propose a novel procedure for bounded determinization of timed automata. The procedure unfolds the automata to bounded trees, removes all silent transitions and determinizes via disjunction of guards. The proposed algorithms are optimized to the bounded setting and thus are more efficient and can handle a larger class of timed automata than the general algorithms. The approach is implemented in a prototype tool and evaluated on several examples. To our best knowledge, this is the first implementation of this type of procedure for timed automata.Comment: 25 page

    Quality of life in female myocardial infarction survivors: a comparative study with a randomly selected general female population cohort

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    Background: A substantial burden associated with MI has been reported. Thus, how survivors experience their quality of life (QOL) is now being given increasing attention. However, few studies have involved women and a comparison with the general population. The aims of this study were to determine the QOL of female MI survivors, to investigate whether their QOL differed from that of the general population, and to evaluate the clinical significance of the findings. Methods: Two cross-sectional surveys were performed; on female MI survivors and the general Norwegian population. The MI survey included women aged 62–80 years, three months to five years after their MI. One hundred and forty-five women responded, yielding a response rate of 60%. A subset of women in the same age range (n = 156) was drawn from a study of 1893 randomly selected Norwegian citizens. QOL was measured in both groups with the World Health Organization Quality of Life Instrument Abbreviated (WHOQOL-BREF). Results: The majority (54%) of the female MI survivors presented with ST-elevation in their ECG, 31% received thrombolysis, and 38% had reduced left ventricular ejection fraction. Female MI survivors reported significantly lower satisfaction with general health (p = 0.020) and overall QOL (p = 0.017) than women from the general population. This was also the case for the physical and environmental QOL domains (p < 0.001), but not for the psychological and social relationship domains. Estimated effect sizes between the two groups of participants ranged from 0.1 to -0.6. Conclusion: The burden of MI significantly affects the physical health of elderly women. Still, female MI survivors fare as well as the general female population on psychosocial QOL domains. Action should be taken not only to support women's physical needs but also to reinforce their strengths in order to maintain optimal QOL

    First-order flow equations for extremal black holes in very special geometry

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    We construct interpolating solutions describing single-center static extremal non-supersymmetric black holes in four-dimensional N=2 supergravity theories with cubic prepotentials. To this end, we derive and solve first-order flow equations for rotating electrically charged extremal black holes in a Taub-NUT geometry in five dimensions. We then use the connection between five- and four-dimensional extremal black holes to obtain four-dimensional flow equations and we give the corresponding solutions.Comment: 21 pages. v2: Summary section adde

    Mastering operational limitations of LEO satellites – The GOMX-3 approach

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    When working with space systems the keyword is resources. For a satellite in orbit all resources are sparse and the most critical resource of all is power. It is therefore crucial to have detailed knowledge on how much power is available for an energy harvesting satellite in orbit at every time – especially when in eclipse, where it draws its power from onboard batteries. This paper addresses this problem by a two-step procedure to perform task scheduling for low-earth-orbit (LEO) satellites exploiting formal methods. It combines cost-optimal reachability analyses of priced timed automata networks with a realistic kinetic battery model capable of capturing capacity limits as well as stochastic fluctuations. The procedure is in use for the automatic and resource-optimal day-ahead scheduling of GOMX-3, a power-hungry nanosatellite currently orbiting the earth. We explain how this approach has overcome existing problems, has led to improved designs, and has provided new insights

    Alpha-states in de Sitter space

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    Field theory in de Sitter space admits a one-parameter family of vacua determined by a superselection parameter alpha. Of these vacua, the Euclidean vacuum uniquely extrapolates to the vacuum of flat Minkowski space. States which resemble the alpha-vacua can be constructed as excitations above the Euclidean vacuum. Such states have modes alpha(k) which decay faster that k^{(1-d)/2}. Fields in such states exhibit non-local correlations when examined from the perspective of fields in the Euclidean vacuum. The dynamics of such entangled states are fully consistent. If an alpha-state with properties that interpolate between an alpha-vacuum and the Euclidean vacuum were the initial condition for inflation, a signature for this may be found in a momentum dependent correction to the inflationary power spectrum. The functional formalism, which provides the tool for examining physics in an alpha-state, extends to fields of other spin. In particular, the extension to spin-2 may proffer a new class of infrared modifications to gravitational interactions. The implications of superselection sectors for the landscape of string vacua are briefly discussed.Comment: 28 pages, LaTe

    De Sitter Holography and the Cosmic Microwave Background

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    We interpret cosmological evolution holographically as a renormalisation group flow in a dual Euclidean field theory, as suggested by the conjectured dS/CFT correspondence. Inflation is described by perturbing around the infra-red fixed point of the dual field theory. The spectrum of the cosmic microwave background radiation is determined in terms of scaling violations in the field theory. The dark energy allows similar, albeit less predictive, considerations. We discuss the cosmological fine-tuning problems from the holographic perspective.Comment: 17 pages, 2 figures, uses JHEP style files; corrected and added reference
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