2,042 research outputs found

    A symbol calculus for Toeplitz operators

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    Longitudinal study of local authority child and family social workers (wave 1) Findings from a 5 year study of local authority child and family social workers in England.

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    The longitudinal study investigates recruitment, retention and career progression in local authority child and family social work over 5 years. This is the first of 5 reports. It provides workforce information for employers and policy makers. Topics covered in this report include: •entry routes into local authority child and family social work •current employment and career history •workplace wellbeing •management, supervision and working environment •job satisfaction •career progression and future career plan

    Discovery of a Transition to Global Spin-up in EXO 2030+375

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    EXO 2030+375, a 42-second transient X-ray pulsar with a Be star companion, has been observed to undergo an outburst at nearly every periastron passage for the last 13.5 years. From 1994 through 2002, the global trend in the pulsar spin frequency was spin-down. Using RXTE data from 2003 September, we have observed a transition to global spin-up in EXO 2030+375. Although the spin frequency observations are sparse, the relative spin-up between 2002 June and 2003 September observations, along with an overall brightening of the outbursts since mid 2002 observed with the RXTE ASM, accompanied by an increase in density of the Be disk, indicated by infrared magnitudes, suggest that the pattern observed with BATSE of a roughly constant spin frequency, followed by spin-up, followed by spin-down is repeating. If so this pattern has approximately an 11 year period, similar to the 15 +/- 3 year period derived by Wilson et al. (2002) for the precession period of a one-armed oscillation in the Be disk. If this pattern is indeed repeating, we predict a transition from spin-up to spin-down in 2005.Comment: Accepted for publication in ApJ Letters, 4 pages, 5 figures, using emulateapj.cl

    Lorentz violating electrodynamics

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    After summarizing the most interesting results in the calculation of synchrotron radiation in the Myers-Pospelov effective model for Lorentz invariance violating (LIV) electrodynamics, we present a general unified way of describing the radiation regime of LIV electrodynamics which include the following three different models : Gambini-Pullin, Ellis et al. and Myers-Pospelov. Such unification reduces to the standard approach of radiation in a dispersive and absortive (in general) medium with a given index of refraction. The formulation is presented up to second order in the LIV parameter and it is explicitly applied to the synchrotron radiation case.Comment: 11 pages, extended version of the talk given by L.F. Urrutia in the VI Mexican School: Approaches to Quantum Gravity, Playa del Carmen, Mexico, Nov. 2004. Minor chages in the text and added reference

    CO-OP Health Plans: Can They Help Fix Rural America\u27s Health Insurance Markets?

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    Consumer-Operated and Oriented Plan (CO-OP) programs are intended to create nonprofit health insurance issuers that would offer health plans to individual and small group markets. Part of the Affordable Care Act, CO-OPs could have a substantial effect on rural healthcare delivery systems. In this Brief, authors Jean Talbot and Andy Coburn of the Maine Rural Health Research Center at the University of Southern Maine provide an overview of the CO-OP program legislation from the Affordable Care Act; identify the challenges to obtaining private health insurance in rural areas; and assess the opportunities and challenges of using the CO-OP program to address the limitations of the rural private health insurance market. Dr. Coburn participated in a webinar on this topic co-hosted by the Rural Assistance Center (RAC) with the State Health Access Reform Evaluation (SHARE)

    Early Optical Polarization of a Gamma Ray Burst Afterglow

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    We report the optical polarization of a gamma ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of gamma rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2-sigma) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region.Comment: 8 pages including 1 figure. Accepted for publication in Science; published online 15 March 2007; 10.1126/science.113848

    The complex process of scaling the integration of technology enhanced learning in mainstream classrooms

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    The early optimism for how technology might transform teaching and learning practices in mainstream school classrooms has long faded in many countries around the world. Whilst early research findings suggested that this was due to obvious barriers such as access to the technology itself, more recent attempts to scale student-access have illuminated other factors and provided a more sound theoretical foundation for us to understanding the processes and products of scaling educational technology innovations. This keynote will use findings from key projects and initiatives to highlight what is being learned – and how this might inform future endeavours to realise a more 21st century curriculum

    Mixing Quantum and Classical Mechanics

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    Using a group theoretical approach we derive an equation of motion for a mixed quantum-classical system. The quantum-classical bracket entering the equation preserves the Lie algebra structure of quantum and classical mechanics: The bracket is antisymmetric and satisfies the Jacobi identity, and, therefore, leads to a natural description of interaction between quantum and classical degrees of freedom. We apply the formalism to coupled quantum and classical oscillators and show how various approximations, such as the mean-field and the multiconfiguration mean-field approaches, can be obtained from the quantum-classical equation of motion.Comment: 31 pages, LaTeX2

    Giant outburst of EXO 2030+375: pulse-phase resolved analysis of INTEGRAL data

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    In June-September 2006 the Be/X-ray binary EXO 2030+375 experienced the second giant outburst since its discovery. The source was shown to have a complicated pulse-averaged X-ray spectral continuum with possible evidence of cyclotron absorption features. In this paper we present the first pulse-phase resolved analysis of the broad band X-ray spectra of EXO 2030+375 obtained with the INTEGRAL observatory close to the maximum and during the decay phase of the giant outburst. We report a strong variability of the spectrum with pulse phase. Alternative spectral continuum models are discussed. The dependence of the spectral parameters on pulse phase during the maximum of the outburst and the evolution of the pulse profiles with time are qualitatively consistent with the pulsar's emission diagram changing from the fan-beam geometry close to the maximum of the outburst to a combination of pencil and fan beams (of comparable intesities) at the end of the decay phase. Evidence of a cyclotron absorption line around 63 keV at the pulse phase interval preceeding the main peak of the pulse profile is present in the spectrum obtained close to the maximum of the outburst.Comment: 8 pages, 10 figures, accepted for publication in A&
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