444,089 research outputs found

    The wrong sort of rebate : the need to reform the UK budget adjustment

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    In this paper we argue that there is a continuing need for some form of rebate mechanism to iron out anomalies in the funding of the EU, but that the particular form of mechanism used to pay the UK a rebate has had severely adverse consequences, and needs to be reformed. Specifically, we argue that the current form of rebate paid to the UK has had perverse incentive effects, which go a long way towards explaining the UK’s semi-detached relationship with the EU

    The iconographic transformation of the “tail of the dragon of the eclipse” into the “hunting cheetah”

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    Medieval Islamic iconography includes many depictions in which the tail of Sagittarius takes the form of the “dragon of the eclipse”. The current paper examines the gradual transformation of this imagery into that of a quadruped, eventually detached from the body of Sagittarius, and placed on the centaur’s back in the characteristic position of the seated “hunting cheetah”, as can also be seen in images of the chase assisted by this feline

    Detection of CI line emission from the detached CO shell of the AGB star R Sculptoris

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    Stars on the asymptotic giant branch (AGB) lose substantial amounts of matter, to the extent that they are important for the chemical evolution of, and dust production in, the universe. The mass loss is believed to increase gradually with age on the AGB, but it may also occur in the form of bursts, possibly related to the thermal pulsing phenomenon. Detached, geometrically thin, CO shells around carbon stars are good signposts of brief and intense mass ejection. We aim to put further constraints on the physical properties of detached CO shells around AGB stars. The photodissociation of CO and other carbon-bearing species in the shells leads to the possibility of detecting lines from neutral carbon. We have therefore searched for the CI(3P13P0^3P_1-\,^3P_0) line at 492 GHz towards two carbon stars, S Sct and R Scl, with detached CO shells of different ages, about 8000 and 2300 years, respectively. The CI(3P13P0^3P_1-\,^3P_0) line was detected towards R Scl. The line intensity is dominated by emission from the detached shell. The detection is at a level consistent with the neutral carbon coming from the full photodissociation of all species except CO, and with only limited photoionisation of carbon. The best fit to the observed 12^{12}CO and 13^{13}CO line intensities, assuming a homogeneous shell, is obtained for a shell mass of about 0.002 MM_\odot, a temperature of about 100 K, and a CO abundance with respect to H2_2 of 103^{-3}. The estimated CI/CO abundance ratio is about 0.3 for the best-fit model. However, a number of arguments point in the direction of a clumpy medium, and a viable interpretation of the data within such a context is provided

    The dynamo bifurcation in rotating spherical shells

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    We investigate the nature of the dynamo bifurcation in a configuration applicable to the Earth's liquid outer core, i.e. in a rotating spherical shell with thermally driven motions. We show that the nature of the bifurcation, which can be either supercritical or subcritical or even take the form of isola (or detached lobes) strongly depends on the parameters. This dependence is described in a range of parameters numerically accessible (which unfortunately remains remote from geophysical application), and we show how the magnetic Prandtl number and the Ekman number control these transitions.Comment: 16 pages, 14 figure

    Dynamically dominant magnetic fields in the diffuse interstellar medium

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    Observations show that magnetic fields in the interstellar medium (ISM) often do not respond to increases in gas density as would be naively expected for a frozen-in field. This may suggest that the magnetic field in the diffuse gas becomes detached from dense clouds as they form. We have investigated this possibility using theoretical estimates, a simple magneto-hydrodynamic model of a flow without mass conservation and numerical simulations of a thermally unstable flow. Our results show that significant magnetic flux can be shed from dense clouds as they form in the diffuse ISM, leaving behind a magnetically dominated diffuse gas.Comment: 2 pages, 1 figure. In proceedings of IAU Symposium 259: "Cosmic magnetic fields: from planets to stars and galaxies", eds. K.G. Strassmeier, A.G. Kosovichev & J.E. Beckman in pres

    Mass Loss Evolution and the Formation of Detached Shells around TP-AGB Stars

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    The origin of the so called 'detached shells' around AGB stars is not fully understood, but two common hypotheses state that these shells form either through the interaction of distinct wind phases or an eruptive mass loss associated with a He-shell flash. We present a model of the formation of detached shells around thermal pulse asymptotic giant branch (TP-AGB) stars, based on detailed modelling of mass loss and stellar evolution, leading to a combination of eruptive mass loss and wind interaction. The purpose of this paper is first of all to connect stellar evolution with wind and mass loss evolution and demonstrate its consistency with observations, but also to show how thin detached shells around TP-AGB stars can be formed. Previous attempts to link mass loss evolution with the formation of detached shells were based on approximate prescriptions for the mass loss and have not included detailed modelling of the wind formation as we do here. (abridged)Comment: 16 pages, 15 figures. Accepted for publication in Astronomy & Astrophysic

    VW LMi: tightest quadruple system known. Light-time effect and possible secular changes of orbits

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    Tightest known quadruple systems VW LMi consists of contact eclipsing binary with P_12 = 0.477551 days and detached binary with P_34 = 7.93063 days revolving in rather tight, 355.0-days orbit. This paper presents new photometric and spectroscopic observations yielding 69 times of minima and 36 disentangled radial velocities for the component stars. All available radial velocities and minima times are combined to better characterize the orbits and to derive absolute parameters of components. The total mass of the quadruple system was estimated at 4.56 M_sun. The detached, non-eclipsing binary with orbital period P = 7.93 days is found to show apsidal motion with U approximately 80 years. Precession period in this binary, caused by the gravitational perturbation of the contact binary, is estimated to be about 120 years. The wide mutual orbit and orbit of the non-eclipsing pair are found to be close to coplanarity, preventing any changes of the inclination angle of the non-eclipsing orbit and excluding occurrence of the second system of eclipses in future. Possibilities of astrometric solution and direct resolving of the wide, mutual orbit are discussed. Nearby star, HD95606, was found to form loose binary with quadruple system VW LMi.Comment: 4 figures. accepted to MNRAS on July 31, 200

    The detached dust and gas shells around the carbon star U Ant

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    Context: Geometrically thin, detached shells of gas have been found around a handful of carbon stars. --Aims: Previous observations of scattered stellar light in the circumstellar medium around the carbon star U Ant were taken through filters centred on the resonance lines of K and Na. These observations could not separate the scattering by dust and atoms. The aim of this paper is to remedy this situation. --Methods: We have obtained polarization data on stellar light scattered in the circumstellar medium around U Ant through filters which contain no strong lines, making it possible to differentiate between the two scattering agents. Kinematic, as well as spatial, information on the gas shells were obtained through high-resolution echelle spectrograph observations of the KI and NaD lines. --Results: We confirm the existence of two detached shells around U Ant. The inner shell (at a radius of approx 43" and a width of approx 2") consists mainly of gas, while the outer shell (at a radius of approx 50" and a width of approx 7") appears to consist exclusively of dust. Both shells appear to have an over-all spherical geometry. The gas shell mass is estimated to be 2x10^-3 M(Sun), while the mass of the dust shell is estimated to be 5x10^-5 M(Sun). The derived expansion velocity, from the KI and NaD lines, of the gas shell, 19.5 km/s, agrees with that obtained from CO radio line data. The inferred shell age is 2700 years. There is structure, e.g. in the form of arcs, inside the gas shell, but it is not clear whether these are due to additional shells. --Conclusions: Our results support the hypothesis that the observed geometrically thin, detached shells around carbon stars are the results of brief periods of intense mass loss, probably associated with thermal pulses, and subsequent wind-wind interactions

    Doping the holographic Mott insulator

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    Mott insulators form because of strong electron repulsions, being at the heart of strongly correlated electron physics. Conventionally these are understood as classical "traffic jams" of electrons described by a short-ranged entangled product ground state. Exploiting the holographic duality, which maps the physics of densely entangled matter onto gravitational black hole physics, we show how Mott-insulators can be constructed departing from entangled non-Fermi liquid metallic states, such as the strange metals found in cuprate superconductors. These "entangled Mott insulators" have traits in common with the "classical" Mott insulators, such as the formation of Mott gap in the optical conductivity, super-exchange-like interactions, and form "stripes" when doped. They also exhibit new properties: the ordering wave vectors are detached from the number of electrons in the unit cell, and the DC resistivity diverges algebraically instead of exponentially as function of temperature. These results may shed light on the mysterious ordering phenomena observed in underdoped cuprates.Comment: 27 pages, 9 figures. Accepted in Nature Physic

    'I-I' and 'I-me' : Transposing Buber's interpersonal attitudes to the intrapersonal plane

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    Hermans' polyphonic model of the self proposes that dialogical relationships can be established between multiple I-positions1 (e.g., Hermans, 2001a). There have been few attempts, however, to explicitly characterize the forms that these intrapersonal relationships may take. Drawing on Buber's (1958) distinction between the 'I-Thou' and 'I-It' attitude, it is proposed that intrapersonal relationships can take one of two forms: an 'I-I' form, in which one I-position encounters and confirms another I-position in its uniqueness and wholeness; and an 'I-Me' form, in which one I-position experiences another I-position in a detached and objectifying way. This article argues that this I-Me form of intrapersonal relating is associated with psychological distress, and that this is so for a number of reasons: Most notably, because an individual who objectifies and subjugates certain I-position cannot reconnect with more central I-positions when dominance reversal (Hermans, 2001a) takes place. On this basis, it is suggested that a key role of the therapeutic process is to help clients become more able to experience moments of I-I intrapersonal encounter, and it is argued that this requires the therapist to confirm the client both as a whole and in terms of each of his or her different voices
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