3,032 research outputs found

    Offside goals and induced breaches of contract

    Get PDF
    An analysis of Global Resources Group Ltd v Mackay which explores the possibility of building links between the offside goals rule and nominate delict of inducing breach of contract

    On a Site of X-ray Emission in AE Aquarii

    Full text link
    An analysis of recently reported results of XMM-Newton observations of AE Aqr within a hypothesis that the detected X-ray source is located inside the Roche lobe of the white dwarf is presented. I show this hypothesis to be inconsistent with the currently adopted model of mass-transfer in the system. Possible solutions of this problem are briefly discussed.Comment: 4 pages, accepted for publication in ApJ Letter

    Some Exact Results on the Potts Model Partition Function in a Magnetic Field

    Full text link
    We consider the Potts model in a magnetic field on an arbitrary graph GG. Using a formula of F. Y. Wu for the partition function ZZ of this model as a sum over spanning subgraphs of GG, we prove some properties of ZZ concerning factorization, monotonicity, and zeros. A generalization of the Tutte polynomial is presented that corresponds to this partition function. In this context we formulate and discuss two weighted graph-coloring problems. We also give a general structural result for ZZ for cyclic strip graphs.Comment: 5 pages, late

    The Prograde Orbit of Exoplanet TrES-2b

    Get PDF
    We monitored the Doppler shift of the G0V star TrES-2 throughout a transit of its giant planet. The anomalous Doppler shift due to stellar rotation (the Rossiter-McLaughlin effect) is discernible in the data, with a signal-to-noise ratio of 2.9, even though the star is a slow rotator. By modeling this effect we find that the planet's trajectory across the face of the star is tilted by -9 +/- 12 degrees relative to the projected stellar equator. With 98% confidence, the orbit is prograde.Comment: ApJ, in press [15 pages

    Higher spin vertex models with domain wall boundary conditions

    Full text link
    We derive determinant expressions for the partition functions of spin-k/2 vertex models on a finite square lattice with domain wall boundary conditions.Comment: 14 pages, 12 figures. Minor corrections. Version to appear in JSTA

    Prospects for the Characterization and Confirmation of Transiting Exoplanets via the Rossiter-McLaughlin Effect

    Get PDF
    The Rossiter-McLaughlin (RM) effect is the distortion of stellar spectral lines that occurs during eclipses or transits, due to stellar rotation. We assess the future prospects for using the RM effect to measure the alignment of planetary orbits with the spin axes of their parent stars, and to confirm exoplanetary transits. We compute the achievable accuracy for the parameters of interest, in general and for the 5 known cases of transiting exoplanets with bright host stars. We determine the requirements for detecting the effects of differential rotation. For transiting planets with small masses or long periods (as will be detected by forthcoming satellite missions), the velocity anomaly produced by the RM effect can be much larger than the orbital velocity of the star. For a terrestrial planet in the habitable zone of a Sun-like star found by the Kepler mission, it will be difficult to use the RM effect to confirm transits with current instruments, but it still may be easier than measuring the spectroscopic orbit.Comment: 18 pages, 8 figures, one table. Minor changes. Accepted to ApJ, to appear in the Jan 20, 2007 issue (v655

    Spanning Trees on Graphs and Lattices in d Dimensions

    Full text link
    The problem of enumerating spanning trees on graphs and lattices is considered. We obtain bounds on the number of spanning trees NSTN_{ST} and establish inequalities relating the numbers of spanning trees of different graphs or lattices. A general formulation is presented for the enumeration of spanning trees on lattices in d2d\geq 2 dimensions, and is applied to the hypercubic, body-centered cubic, face-centered cubic, and specific planar lattices including the kagom\'e, diced, 4-8-8 (bathroom-tile), Union Jack, and 3-12-12 lattices. This leads to closed-form expressions for NSTN_{ST} for these lattices of finite sizes. We prove a theorem concerning the classes of graphs and lattices L{\cal L} with the property that NSTexp(nzL)N_{ST} \sim \exp(nz_{\cal L}) as the number of vertices nn \to \infty, where zLz_{\cal L} is a finite nonzero constant. This includes the bulk limit of lattices in any spatial dimension, and also sections of lattices whose lengths in some dimensions go to infinity while others are finite. We evaluate zLz_{\cal L} exactly for the lattices we considered, and discuss the dependence of zLz_{\cal L} on d and the lattice coordination number. We also establish a relation connecting zLz_{\cal L} to the free energy of the critical Ising model for planar lattices L{\cal L}.Comment: 28 pages, latex, 1 postscript figure, J. Phys. A, in pres
    corecore