7,326 research outputs found

    Precession during merger 1: Strong polarization changes are observationally accessible features of strong-field gravity during binary black hole merger

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    The short gravitational wave signal from the merger of compact binaries encodes a surprising amount of information about the strong-field dynamics of merger into frequencies accessible to ground-based interferometers. In this paper we describe a previously-unknown "precession" of the peak emission direction with time, both before and after the merger, about the total angular momentum direction. We demonstrate the gravitational wave polarization encodes the orientation of this direction to the line of sight. We argue the effects of polarization can be estimated nonparametrically, directly from the gravitational wave signal as seen along one line of sight, as a slowly-varying feature on top of a rapidly-varying carrier. After merger, our results can be interpreted as a coherent excitation of quasinormal modes of different angular orders, a superposition which naturally "precesses" and modulates the line-of-sight amplitude. Recent analytic calculations have arrived at a similar geometric interpretation. We suspect the line-of-sight polarization content will be a convenient observable with which to define new high-precision tests of general relativity using gravitational waves. Additionally, as the nonlinear merger process seeds the initial coherent perturbation, we speculate the amplitude of this effect provides a new probe of the strong-field dynamics during merger. To demonstrate the ubiquity of the effects we describe, we summarize the post-merger evolution of 104 generic precessing binary mergers. Finally, we provide estimates for the detectable impacts of precession on the waveforms from high-mass sources. These expressions may identify new precessing binary parameters whose waveforms are dissimilar from the existing sample.Comment: 11 figures; v2 includes response to referee suggestion

    Tunable coaxial resonators based on silicon optical fibers

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    Thermal tuning of a coaxial fiber resonator with a silica cladding surrounding an inner silicon core is investigated. By pumping the silicon with below bandgap light, it is possible to redshift the WGM resonances

    Systemic Administration of Tolerogenic Dendritic Cells Ameliorates Murine Inflammatory Arthritis

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    The expression of various cell surface molecules and the production of certain cytokines are important mechanisms by which dendritic cells (DC) are able to bias immune responses. This paper describes the effects of the inflammatory cytokine tumor necrosis factor (TNF)-α on DC phenotype and function. TNF-α treatment resulted in upregulation of MHC class II and CD86 in the absence of increased cell surface CD40 and CD80 or the production of IL-12. Additionally TNF-α treated cells were able to bias T cell responses towards an anti-inflammatory profile. On a note of caution this tolerogenic phenotype of the DC was not stable upon subsequent TLR-4 ligation as a 4 hour pulse of the TNF-α treated DC with lipopolysaccharide (LPS) resulted in the restoration of IL-12 production and an enhancement of their T cell stimulatory capacity which resulted in an increased IFN-γ production. However, TNF-α treated DC, when administered in vivo, were shown to ameliorate disease in collagen induced arthritis, an experimental model of inflammatory joint disease. Mice receiving TNF-α treated DC but not LPS matured DC had a delayed onset, and significantly reduced severity, of arthritis. Disease suppression was associated with reduced levels of collagen specific IgG2a and decreased inflammatory cell infiltration into affected joints. In summary the treatment of DC with TNF-α generates an antigen presenting cell with a phenotype that can reduce the pro-inflammatory response and direct the immune system towards a disease modifying, anti-inflammatory state

    Re Ass\u27n of Radio & Television Employees and Canadian Broadcasting Corp

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    Employee Grievance alleging unjust discharge. Award (in part) It is widely accepted by labour arbitration boards in Ontario that the onus of proving just cause is on the company in dismissal cases, where the collective agreement contains the usual provision and there is no practice to the contrary clearly established between the parties. See for example Re Int\u27l Ass\u27n of Machinists, Local 749, and Timken Roller Bearing Co. (1952), 4 L.A.C. 1262 (E.W. Cross, C.C.J., chairman); Re United Brewery Workers and Dow Kingsbeer Brewery Ltd. (1958), 8 L.A.C.198 (B. Laskin, chairman), and Re U.E.W., Local 504, and Canadian Westinghouse Co. Ltd. (1966), 17 L.A.C. 427 (E.E. Palmer, chairman). The last of these cases is a discipline case in which Professor Palmer decided that the rule in discharge cases, which puts the onus on the company, should be extended, and cites the decisions of other arbitrators agreeing with him. It is unnecessary for us to deal with this point, but the awards cited by Professor Palmer establish beyond doubt that the normal rule in Ontario is for the company to bear the onus of proving just cause in discharge cases

    A descriptive epidemiological study of mastitis in 12 Irish dairy herds

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    <p/> <p>Factors relating to the occurrence of mastitis were studied on 12 Irish dairy herds with histories of elevated somatic cell count (SCC) and/or increased incidence of clinical mastitis cases. Milk recording data were analysed, housing conditions and calving areas were examined; dry cow therapy, clinical mastitis records, milking technique and aspects of milking machine function were assessed.</p> <p>Herds with a ratio of less than 110 cubicles per 100 cows were more likely to experience environmental mastitis. Herds with inadequate calving facilities, where cows spent prolonged periods on straw bedding, were likely to acquire environmental mastitis. In the majority of the herds, the selection of dry cow therapy lacked adequate planning. The majority of farmers took no action to reduce pain experienced by cows suffering mastitis. Deficiencies in parlour hygiene were evident in all herds experiencing elevation in SCC.</p

    An Exactly Solved Model of Three Dimensional Surface Growth in the Anisotropic KPZ Regime

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    We generalize the surface growth model of Gates and Westcott to arbitrary inclination. The exact steady growth velocity is of saddle type with principal curvatures of opposite sign. According to Wolf this implies logarithmic height correlations, which we prove by mapping the steady state of the surface to world lines of free fermions with chiral boundary conditions.Comment: 9 pages, REVTEX, epsf, 3 postscript figures, submitted to J. Stat. Phys, a wrong character is corrected in eqs. (31) and (32

    Non-perturbative renormalization of the KPZ growth dynamics

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    We introduce a non-perturbative renormalization approach which identifies stable fixed points in any dimension for the Kardar-Parisi-Zhang dynamics of rough surfaces. The usual limitations of real space methods to deal with anisotropic (self-affine) scaling are overcome with an indirect functional renormalization. The roughness exponent α\alpha is computed for dimensions d=1d=1 to 8 and it results to be in very good agreement with the available simulations. No evidence is found for an upper critical dimension. We discuss how the present approach can be extended to other self-affine problems.Comment: 4 pages, 2 figures. To appear in Phys. Rev. Let
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