995 research outputs found

    CTips, Issue 4: Bias

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    Evaluation of be-38 percent al alloy final report, 27 jun. 1964 - 28 feb. 1965

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    Mechanical properties, microstructural features, and general metallurgical quality of beryllium- aluminum allo

    Predicting the coherence resonance curve using a semi-analytical treatment

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    Emergence of noise induced regularity or Coherence Resonance in nonlinear excitable systems is well known. We explain theoretically why the normalized variance (VNV_{N}) of inter spike time intervals, which is a measure of regularity in such systems, has a unimodal profile. Our semi-analytic treatment of the associated spiking process produces a general yet simple formula for VNV_{N}, which we show is in very good agreement with numerics in two test cases, namely the FitzHugh-Nagumo model and the Chemical Oscillator model.Comment: 5 pages, 5 figure

    Coherence Resonance and Noise-Induced Synchronization in Globally Coupled Hodgkin-Huxley Neurons

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    The coherence resonance (CR) of globally coupled Hodgkin-Huxley neurons is studied. When the neurons are set in the subthreshold regime near the firing threshold, the additive noise induces limit cycles. The coherence of the system is optimized by the noise. A bell-shaped curve is found for the peak height of power spectra of the spike train, being significantly different from a monotonic behavior for the single neuron. The coupling of the network can enhance CR in two different ways. In particular, when the coupling is strong enough, the synchronization of the system is induced and optimized by the noise. This synchronization leads to a high and wide plateau in the local measure of coherence curve. The local-noise-induced limit cycle can evolve to a refined spatiotemporal order through the dynamical optimization among the autonomous oscillation of an individual neuron, the coupling of the network, and the local noise.Comment: five pages, five figure

    Codimension-2 surfaces and their Hilbert spaces: low-energy clues for holography from general covariance

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    We argue that the holographic principle may be hinted at already from low-energy considerations, assuming diffeomorphism invariance, quantum mechanics and Minkowski-like causality. We consider the states of finite spacelike hypersurfaces in a diffeomorphism-invariant QFT. A low-energy regularization is assumed. We note a natural dependence of the Hilbert space on a codimension-2 boundary surface. The Hilbert product is defined dynamically, in terms of transition amplitudes which are described by a path integral. We show that a canonical basis is incompatible with these assumptions, which opens the possibility for a smaller Hilbert-space dimension than canonically expected. We argue further that this dimension may decrease with surface area at constant volume, hinting at holographic area-proportionality. We draw comparisons with other approaches and setups, and propose an interpretation for the non-holographic space of graviton states at asymptotically-Minkowski null infinity.Comment: 13 pages, 9 eps figures. Added Section VI, improved presentation. Expanded and split the Introduction into two sections. Added Section VII. Added reference

    Triggering synchronized oscillations through arbitrarily weak diversity in close-to-threshold excitable media

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    It is shown that arbitrarily weak (frozen) heterogeneity can induce global synchronized oscillations in excitable media close to threshold. The work is carried out on networks of coupled van der Pol-FitzHugh-Nagumo oscillators. The result is shown to be robust against the presence of internal dynamical noise.Comment: 4 pages (RevTeX 3 style), 5 EPS figures, submitted to Phys. Rev. E (16 aug 2001

    State of Vermont Health Care Financing Plan Beginning Calendar Year 2017 Analysis

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    This report, prepared for the Vermont Agency of Administration, details the costs and coverage of a single-payer system in Vermont, and explained that the state must develop new financing mechanisms that raise $1.6 billion to fund single-payer. It was produced in partnership with Wakely Consulting Group Inc. However, on December 17, 2014, Gov. Peter Shumlin announced that now is not the right time to overhaul health care financing and delivery in Vermont

    The problem of shot selection in basketball

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    In basketball, every time the offense produces a shot opportunity the player with the ball must decide whether the shot is worth taking. In this paper, I explore the question of when a team should shoot and when they should pass up the shot by considering a simple theoretical model of the shot selection process, in which the quality of shot opportunities generated by the offense is assumed to fall randomly within a uniform distribution. I derive an answer to the question "how likely must the shot be to go in before the player should take it?", and show that this "lower cutoff" for shot quality ff depends crucially on the number nn of shot opportunities remaining (say, before the shot clock expires), with larger nn demanding that only higher-quality shots should be taken. The function f(n)f(n) is also derived in the presence of a finite turnover rate and used to predict the shooting rate of an optimal-shooting team as a function of time. This prediction is compared to observed shooting rates from the National Basketball Association (NBA), and the comparison suggests that NBA players tend to wait too long before shooting and undervalue the probability of committing a turnover.Comment: 7 pages, 2 figures; comparison to NBA data adde
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