18,833 research outputs found

    Small and medium agility dogs alter their kinematics when the distance between hurdles differs

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    There is currently a lack of research examining the health and welfare implications for competitive agility dogs. The aim of this study was to examine if jump kinematics and apparent joint angles in medium (351 mm - 430 mm to the withers) and small (< 350 mm to the withers) agility dogs altered when distances between consecutive upright hurdles differ. Dogs ran a course of nine hurdles; three set at 3.6 m apart; three at 4 m apart and three at 5 m apart. Both medium (P=0.044) and small (P=0.006) dogs landed closer to the hurdle when consecutive hurdles were set at 3.6 m apart, with small dogs jumping slower at this distance (P=0.006). Results indicate that jump kinematics, but not apparent joint angles, alter when the spacing between hurdles differs. These findings may have implications for the health and welfare of agility dogs and should be used to inform future changes to rules and regulations

    The Large Peculiar Velocity of the cD Galaxy in Abell 3653

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    We present a catalogue of galaxies in Abell 3653 from observations made with the 2dF spectrograph at the Anglo-Australian Telescope. Of the 391 objects observed, we find 111 are bone-fide members of Abell 3653. We show that the cluster has a velocity of cz = 32214 +/- 83 km/s (z=0.10738 +/- 0.00027), with a velocity dispersion typical of rich, massive clusters of sigma_{cz} = 880^{+66}_{-54}. We find that the cD galaxy has a peculiar velocity of 683 +/- 96 km/s in the cluster restframe - some 7sigma away from the mean cluster velocity, making it one of the largest and most significant peculiar velocities found for a cD galaxy to date. We investigate the cluster for signs of substructure, but do not find any significant groupings on any length scale. We consider the implications of our findings on cD formation theories.Comment: 16 pages, including 7 figures and a long table. Accepted for publication in MNRA

    Chromospheric Inversions of a Micro-flaring Region

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    We use spectropolarimetric observations of the Ca II 8542~\AA\ line, taken from the Swedish 1-m Solar Telescope (SST), in an attempt to recover dynamic activity in a micro-flaring region near a sunspot via inversions. These inversions show localized mean temperature enhancements of \sim1000~K in the chromosphere and upper photosphere, along with co-spatial bi-directional Doppler shifting of 5 - 10 km s1^{-1}. This heating also extends along a nearby chromospheric fibril, co-spatial to 10 - 15 km s1^{-1} down-flows. Strong magnetic flux cancellation is also apparent in one of the footpoints, concentrated in the chromosphere. This event more closely resembles that of an Ellerman Bomb (EB), though placed slightly higher in the atmosphere than is typically observed.Comment: 9 pages, 9 figures, accepted in ApJ. Movies are stored here: https://star.pst.qub.ac.uk/webdav/public/areid/Microflare

    Coronal hole boundaries at small scales: IV. SOT view Magnetic field properties of small-scale transient brightenings in coronal holes

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    We study the magnetic properties of small-scale transients in coronal hole. We found all brightening events are associated with bipolar regions and caused by magnetic flux emergence followed by cancellation with the pre-existing and newly emerging magnetic flux. In the coronal hole, 19 of 22 events have a single stable polarity which does not change its position in time. In eleven cases this is the dominant polarity. The dominant flux of the coronal hole form the largest concentration of magnetic flux in terms of size while the opposite polarity is distributed in small concentrations. In the coronal hole the number of magnetic elements of the dominant polarity is four times higher than the non-dominant one. The supergranulation configuration appears to preserve its general shape during approximately nine hours of observations although the large concentrations in the network did evolve and were slightly displaced, and their strength either increased or decreased. The emission fluctuations seen in the X-ray bright points are associated with reoccurring magnetic cancellation in the footpoints. Unique observations of an X-ray jet reveal similar magnetic behaviour in the footpoints, i.e. cancellation of the opposite polarity magnetic flux. We found that the magnetic flux cancellation rate during the jet is much higher than in bright points. Not all magnetic cancellations result in an X-ray enhancement, suggesting that there is a threshold of the amount of magnetic flux involved in a cancellation above which brightening would occur at X-ray temperatures. Our study demonstrates that the magnetic flux in coronal holes is continuously recycled through magnetic reconnection which is responsible for the formation of numerous small-scale transient events. The open magnetic flux forming the coronal-hole phenomenon is largely involved in these transient features.Comment: 19 pages, 18 figures, A&A in pres

    Diagnosing transient ionization in dynamic events

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    The present study aims to provide a diagnostic line ratio that will enable the observer to determine whether a plasma is in a state of transient ionization. We use the Atomic Data and Analysis Structure (ADAS) to calculate line contribution functions for two lines, Si IV 1394 A and O IV 1401 A, formed in the solar transition region. The generalized collisional-radiative theory is used. It includes all radiative and electron collisional processes, except for photon-induced processes. State-resolved direct ionization and recombination to and from the next ionization stage are also taken into account. For dynamic bursts with a decay time of a few seconds, the Si IV 1394 A line can be enhanced by a factor of 2-4 in the first fraction of a second with the peak in the line contribution function occurring initially at a higher electron temperature due to transient ionization compared to ionization equilibrium conditions. On the other hand, the O IV 1401 A does not show such any enhancement. Thus the ratio of these two lines, which can be observed with the Interface Region Imaging Spectrograph, can be used as a diagnostic of transient ionization. We show that simultaneous high-cadence observations of two lines formed in the solar transition region may be used as a direct diagnostic of whether the observed plasma is in transient ionization. The ratio of these two lines can change by a factor of four in a few seconds owing to transient ionization alone.Comment: 3 pages, in press A&

    Measuring device Patent

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    Expulsion and measuring device for determining quantity of liquid in tank under conditions of weightlessnes

    Brands in international and multi‐platform expansion strategies: economic and management issues

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    Powerful media branding has historically facilitated successful international expansion on the part of magazine and other content forms including film and TV formats. Multi-platform expansion is now increasingly central to the strategies of media companies and, as this chapter argues, effective use of branding in order to engage audiences effectively and to secure a prominent presence across digital platforms forms a core part of this. Drawing on original research into the experience of UK media companies, this chapter highlights some of the key economic, management and socio-cultural issues raised by the ever-increasing role of brands and branding in the strategies of international and multi-platform expansion that are increasingly common- place across media

    Calculating effective resistances on underlying networks of association schemes

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    Recently, in Refs. \cite{jsj} and \cite{res2}, calculation of effective resistances on distance-regular networks was investigated, where in the first paper, the calculation was based on stratification and Stieltjes function associated with the network, whereas in the latter one a recursive formula for effective resistances was given based on the Christoffel-Darboux identity. In this paper, evaluation of effective resistances on more general networks which are underlying networks of association schemes is considered, where by using the algebraic combinatoric structures of association schemes such as stratification and Bose-Mesner algebras, an explicit formula for effective resistances on these networks is given in terms of the parameters of corresponding association schemes. Moreover, we show that for particular underlying networks of association schemes with diameter dd such that the adjacency matrix AA possesses d+1d+1 distinct eigenvalues, all of the other adjacency matrices AiA_i, i0,1i\neq 0,1 can be written as polynomials of AA, i.e., Ai=Pi(A)A_i=P_i(A), where PiP_i is not necessarily of degree ii. Then, we use this property for these particular networks and assume that all of the conductances except for one of them, say cc1=1c\equiv c_1=1, are zero to give a procedure for evaluating effective resistances on these networks. The preference of this procedure is that one can evaluate effective resistances by using the structure of their Bose-Mesner algebra without any need to know the spectrum of the adjacency matrices.Comment: 41 page

    A Dynamical Analysis of the Proposed Circumbinary HW Virginis Planetary System

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    In 2009, the discovery of two planets orbiting the evolved binary star system HW Virginis was announced, based on systematic variations in the timing of eclipses between the two stars. The planets invoked in that work were significantly more massive than Jupiter, and moved on orbits that were mutually crossing - an architecture which suggests that mutual encounters and strong gravitational interactions are almost guaranteed. In this work, we perform a highly detailed analysis of the proposed HW Vir planetary system. First, we consider the dynamical stability of the system as proposed in the discovery work. Through a mapping process involving 91,125 individual simulations, we find that the system is so unstable that the planets proposed simply cannot exist, due to mean lifetimes of less than a thousand years across the whole parameter space. We then present a detailed re-analysis of the observational data on HW Vir, deriving a new orbital solution that provides a very good fit to the observational data. Our new analysis yields a system with planets more widely spaced, and of lower mass, than that proposed in the discovery work, and yields a significantly greater (and more realistic) estimate of the uncertainty in the orbit of the outermost body. Despite this, a detailed dynamical analysis of this new solution similarly reveals that it also requires the planets to move on orbits that are simply not dynamically feasible. Our results imply that some mechanism other than the influence of planetary companions must be the principal cause of the observed eclipse timing variations for HW Vir. If the sys- tem does host exoplanets, they must move on orbits differing greatly from those previously proposed. Our results illustrate the critical importance of performing dynamical analyses as a part of the discovery process for multiple-planet exoplanetary systems.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Societ

    Buffer gas cooling and trapping of atoms with small magnetic moments

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    Buffer gas cooling was extended to trap atoms with small magnetic moment (mu). For mu greater than or equal to 3mu_B, 1e12 atoms were buffer gas cooled, trapped, and thermally isolated in ultra high vacuum with roughly unit efficiency. For mu < 3mu_B, the fraction of atoms remaining after full thermal isolation was limited by two processes: wind from the rapid removal of the buffer gas and desorbing helium films. In our current apparatus we trap atoms with mu greater than or equal to 1.1mu_B, and thermally isolate atoms with mu greater than or equal to 2mu_B. Extrapolation of our results combined with simulations of the loss processes indicate that it is possible to trap and evaporatively cool mu = 1mu_B atoms using buffer gas cooling.Comment: 17 pages, 4 figure
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