1,987 research outputs found

    Dual Anion-Cation Ionic Liquid Crystal for Battery Applications

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    Ionic liquid crystals (ILCs) are a special class of compounds that not only contains mesogens group but also have cationic and/or anionic components. ILCs can self-organize into assemblies with varying degrees of orientational order resulting into formation of unique liquid crystal phases. Thermotropic ionic liquid crystals are special subclass of liquid crystal containing ionic liquid moiety that self- assemble with application of heat to form liquid crystal phases. Thermotropic ionic liquid crystal materials may exhibit several mesogenic phases at differing temperatures, distinguishable by the degree of order. This work mainly focuses on synthesis and characterization of Ionic liquid Crystals containing imidazolium and sulfonimide functional group attached to phenyl ring containing long chain alkyl group. In this presentation we will focus on how change in alkyl tail, change in ionic component (sulfonimide vs imidazolium) , and counter ion (i.e., triethyl ammonium vs Lithium cation) present in the compound, affect the liquid crystal properties. The synthesized ILCs was characterized by TGA, DSC and SAXS data. Keywords: Ionic liquids, Liquid crystals, Dual Cation-Anion, Batterie

    New periodic variable stars coincident with ROSAT sources discovered using SuperWASP

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    We present optical lightcurves of 428 periodic variable stars coincident with ROSAT X-ray sources, detected using the first run of the SuperWASP photometric survey. Only 68 of these were previously recognised as periodic variables. A further 30 of these objects are previously known pre-main sequence stars, for which we detect a modulation period for the first time. Amongst the newly identified periodic variables, many appear to be close eclipsing binaries, their X-ray emission is presumably the result of RS CVn type behaviour. Others are probably BY Dra stars, pre-main sequence stars and other rapid rotators displaying enhanced coronal activity. A number of previously catalogued pulsating variables (RR Lyr stars and Cepheids) coincident with X-ray sources are also seen, but we show hat these are likely to be misclassifications. We identify four objects which are probable low mass eclipsing binary stars, based on their very red colour and light curve morphology

    Mixed Methods Use in Project Management Research

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    Mixed methods research is increasingly being used in business and management disciplines, in spite of positivist traditions. The aim of the study is twofold: (1) to examine the types of mixed methods approaches being used, and (2) to determine the quality of the reporting of mixed methods studies published in the field of project management. A retrospective content analysis of articles from three ranked project management journals was undertaken for a sample period of 2004 to 2010. Our findings suggest the field of project management is in need of capacity building in relation to the good reporting of mixed methods studies

    The well-aligned orbit of WASP-84b: evidence for disc migration

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    We report the sky-projected orbital obliquity (spin-orbit angle) of WASP-84b, a 0.70-MJupM_{\rm Jup} planet in a 8.52-day orbit around a G9V/K0V star, to be λ=0.3±1.7∘\lambda = 0.3 \pm 1.7^\circ. We obtain a true obliquity of ψ=14.8±8.0∘\psi = 14.8 \pm 8.0^\circ from a measurement of the inclination of the stellar spin axis with respect to the sky plane. Due to the young age and the weak tidal forcing of the system, we suggest that the orbit of WASP-84b is unlikely to have both realigned and circularised from the misaligned and/or eccentric orbit likely to have arisen from high-eccentricity migration. Therefore we conclude that the planet probably migrated via interaction with the protoplanetary disc. This would make it the first short-orbit, giant planet to have been shown to have migrated via this pathway. Further, we argue that the distribution of obliquities for planets orbiting cool stars (TeffT_{\rm eff} < 6250 K) suggests that high-eccentricity migration is an important pathway for the formation of short-orbit, giant planets.Comment: 6 pages, 3 figures, 1 table, submitted to ApJ

    WASP-189b: an ultra-hot Jupiter transiting the bright A star HR 5599 in a polar orbit

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    We report the discovery of WASP-189b: an ultra-hot Jupiter in a 2.72-d transiting orbit around the V=6.6V = 6.6 A star WASP-189 (HR 5599). We detected periodic dimmings in the star's lightcurve, first with the WASP-South survey facility then with the TRAPPIST-South telescope. We confirmed that a planet is the cause of those dimmings via line-profile tomography and radial-velocity measurements using the HARPS and CORALIE spectrographs. Those reveal WASP-189b to be an ultra-hot Jupiter (MPM_{\rm P} = 2.13 ±\pm 0.28 MJupM_{\rm Jup}; RPR_{\rm P} = 1.374 ±\pm 0.082 RJupR_{\rm Jup}) in a polar orbit (λ=89.3±1.4∘\lambda = 89.3 \pm 1.4^\circ; Κ=90.0±5.8∘\Psi = 90.0 \pm 5.8^\circ) around a rapidly rotating A6IV-V star (TeffT_{\rm eff} = 8000 ±\pm 100 K; v∗sin⁥i∗v_* \sin i_* ≈\approx 100 km\, s−1^{-1}). We calculate a predicted equilibrium temperature of TeqlT_{\rm eql} = 2641 ±\pm 34 K, assuming zero albedo and efficient redistribution, which is the third hottest for the known exoplanets. WASP-189 is the brightest known host of a transiting hot Jupiter and the third-brightest known host of any transiting exoplanet. We note that of the eight hot-Jupiter systems with TeffT_{\rm eff} >> 7000 K, seven have strongly misaligned orbits, and two of the three systems with TeffT_{\rm eff} ≄\geq 8000 K have polar orbits (the third is aligned).Comment: Submitted to MNRAS. 10 pages, 9 figures, 3 table

    Academic freedom in Europe: time for a Magna Charta?

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    This paper is a preliminary attempt to establish a working definition of academic freedom for the European Union states. The paper details why such a definition is required for the European Union and then examines some of the difficulties of defining academic freedom. By drawing upon experience of the legal difficulties beset by the concept in the USA and building on previous analyses of constitutional and legislative protection for academic freedom, and of legal regulations concerning institutional governance and academic tenure, a working definition of academic freedom is then derived. The resultant definition which, it is suggested, could form the basis for a European Magna Charta Libertatis Academicae, goes beyond traditional discussions of academic freedom by specifying not only the rights inherent in the concept but also its accompanying duties, necessary limitations and safeguards. The paper concludes with proposals for how the definition might be tested and carried forward

    Phylogenetic comparative analysis of electric communication signals in ghost knifefishes (Gymnotiformes: Apteronotidae)

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    Electrocommunication signals in electric fish are diverse, easily recorded and have well-characterized neural control. Two signal features, the frequency and waveform of the electric organ discharge (EOD), vary widely across species. Modulations of the EOD (i.e. chirps and gradual frequency rises) also function as active communication signals during social interactions, but they have been studied in relatively few species. We compared the electrocommunication signals of 13 species in the largest gymnotiform family, Apteronotidae. Playback stimuli were used to elicit chirps and rises. We analyzed EOD frequency and waveform and the production and structure of chirps and rises. Species diversity in these signals was characterized with discriminant function analyses, and correlations between signal parameters were tested with phylogenetic comparative methods. Signals varied markedly across species and even between congeners and populations of the same species. Chirps and EODs were particularly evolutionarily labile, whereas rises differed little across species. Although all chirp parameters contributed to species differences in these signals, chirp amplitude modulation, frequency modulation (FM) and duration were particularly diverse. Within this diversity, however, interspecific correlations between chirp parameters suggest that mechanistic trade-offs may shape some aspects of signal evolution. In particular, a consistent trade-off between FM and EOD amplitude during chirps is likely to have influenced the evolution of chirp structure. These patterns suggest that functional or mechanistic linkages between signal parameters (e.g. the inability of electromotor neurons increase their firing rates without a loss of synchrony or amplitude of action potentials) constrain the evolution of signal structure

    Astrophysical Axion Bounds

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    Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational consequences include a modification of the solar sound-speed profile, an increase of the solar neutrino flux, a reduction of the helium-burning lifetime of globular-cluster stars, accelerated white-dwarf cooling, and a reduction of the supernova SN 1987A neutrino burst duration. We review and update these arguments and summarize the resulting axion constraints.Comment: Contribution to Axion volume of Lecture Notes in Physics, 20 pages, 3 figure

    On a Light Spinless Particle Coupled to Photons

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    A pseudoscalar or scalar particle ϕ\phi that couples to two photons but not to leptons, quarks and nucleons would have effects in most of the experiments searching for axions, since these are based on the aγγa \gamma \gamma coupling. We examine the laboratory, astrophysical and cosmological constraints on ϕ\phi and study whether it may constitute a substantial part of the dark matter. We also generalize the ϕ\phi interactions to possess SU(2)×U(1)SU(2) \times U(1) gauge invariance, and analyze the phenomenological implications.Comment: LaTex, 20p., 6 figures. Changes in sections 4, 5 and figure 2, our bounds are now more stringent. To be published in Physical Review
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