2,498 research outputs found

    New Limits on Local Lorentz Invariance in Mercury and Cesium

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    We report new bounds on Local Lorentz Invariance (LLI) violation in Cs and Hg. The limits are obtained through the observation of the the spin- precession frequencies of 199Hg and 133Cs atoms in their ground states as a function of the orientation of an applied magnetic field with respect to the fixed stars. We measure the amplitudes of the dipole couplings to a preferred direction in the equatorial plane to be 19(11) nHz for Hg and 9(5) microHz for Cs. The upper bounds established here improve upon previous bounds by about a factor of four. The improvement is primarily due to mounting the apparatus on a rotating table. New bounds are established on several terms in the standard model extension including the first bounds on the spin-couplings of the neutron and proton to the z direction, <7e-30 GeV and <7e-29 GeV, respectively.Comment: 17 pages, 6 figure

    Time-dependent fields and anisotropy dominated magnetic media

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    We use a single dipole approximation to analyze the behavior of anisotropy-dominated magnetic nanoparticles subjected to an external r.f. field. We identify the steady state oscillations and analyze their stability. We also analyze the case when the external r.f. field has a time-dependent frequency which insures the most effective switching of the magnetization

    A L\'evy input fluid queue with input and workload regulation

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    We consider a queuing model with the workload evolving between consecutive i.i.d.\ exponential timers {eq(i)}i=1,2,...\{e_q^{(i)}\}_{i=1,2,...} according to a spectrally positive L\'evy process Yi(t)Y_i(t) that is reflected at zero, and where the environment ii equals 0 or 1. When the exponential clock eq(i)e_q^{(i)} ends, the workload, as well as the L\'evy input process, are modified; this modification may depend on the current value of the workload, the maximum and the minimum workload observed during the previous cycle, and the environment ii of the L\'evy input process itself during the previous cycle. We analyse the steady-state workload distribution for this model. The main theme of the analysis is the systematic application of non-trivial functionals, derived within the framework of fluctuation theory of L\'evy processes, to workload and queuing models

    The victorious English language: hegemonic practices in the management academy

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    This study explores hegemonic linguistic processes, that is, the dominant and unreflective use of the English language in the production of textual knowledge accounts. The authors see the production of management knowledge as situated in central or peripheral locations, which they examine from an English language perspective. Their inquiry is based on an empirical study based on the perspectives of 33 management academics (not English language speakers) in (semi) peripheral locations, who have to generate and disseminate knowledge in and through the English language. Although the hegemony of the center in the knowledge production process has long been acknowledged, the specific contribution of this study is to explore how the English language operates as part of the “ideological complex” that produces and maintains this hegemony, as well as how this hegemony is manifested at the local level of publication practices in peripherally located business and management schools

    Spike-Train Responses of a Pair of Hodgkin-Huxley Neurons with Time-Delayed Couplings

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    Model calculations have been performed on the spike-train response of a pair of Hodgkin-Huxley (HH) neurons coupled by recurrent excitatory-excitatory couplings with time delay. The coupled, excitable HH neurons are assumed to receive the two kinds of spike-train inputs: the transient input consisting of MM impulses for the finite duration (MM: integer) and the sequential input with the constant interspike interval (ISI). The distribution of the output ISI ToT_{\rm o} shows a rich of variety depending on the coupling strength and the time delay. The comparison is made between the dependence of the output ISI for the transient inputs and that for the sequential inputs.Comment: 19 pages, 4 figure
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