2,451 research outputs found

    A note on entropic uncertainty relations of position and momentum

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    We consider two entropic uncertainty relations of position and momentum recently discussed in literature. By a suitable rescaling of one of them, we obtain a smooth interpolation of both for high-resolution and low-resolution measurements respectively. Because our interpolation has never been mentioned in literature before, we propose it as a candidate for an improved entropic uncertainty relation of position and momentum. Up to now, the author has neither been able to falsify nor prove the new inequality. In our opinion it is a challenge to do either one.Comment: 2 pages, 2 figures, 2 references adde

    Dynamical response of the Hodgkin-Huxley model in the high-input regime

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    The response of the Hodgkin-Huxley neuronal model subjected to stochastic uncorrelated spike trains originating from a large number of inhibitory and excitatory post-synaptic potentials is analyzed in detail. The model is examined in its three fundamental dynamical regimes: silence, bistability and repetitive firing. Its response is characterized in terms of statistical indicators (interspike-interval distributions and their first moments) as well as of dynamical indicators (autocorrelation functions and conditional entropies). In the silent regime, the coexistence of two different coherence resonances is revealed: one occurs at quite low noise and is related to the stimulation of subthreshold oscillations around the rest state; the second one (at intermediate noise variance) is associated with the regularization of the sequence of spikes emitted by the neuron. Bistability in the low noise limit can be interpreted in terms of jumping processes across barriers activated by stochastic fluctuations. In the repetitive firing regime a maximization of incoherence is observed at finite noise variance. Finally, the mechanisms responsible for spike triggering in the various regimes are clearly identified.Comment: 14 pages, 24 figures in eps, submitted to Physical Review

    Fidelity of Quantum Interferometers

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    For a generic interferometer, the conditional probability density distribution, p(ϕ∣m)p(\phi|m), for the phase ϕ\phi given measurement outcome mm, will generally have multiple peaks. Therefore, the phase sensitivity of an interferometer cannot be adequately characterized by the standard deviation, such as Δϕ∼1/N\Delta\phi\sim 1/\sqrt{N} (the standard limit), or Δϕ∼1/N\Delta\phi\sim 1/N (the Heisenberg limit). We propose an alternative measure of phase sensitivity--the fidelity of an interferometer--defined as the Shannon mutual information between the phase shift ϕ\phi\ and the measurement outcomes mm. As an example application of interferometer fidelity, we consider a generic optical Mach-Zehnder interferometer, used as a sensor of a classical field. We find the surprising result that an entangled {\it N00N} state input leads to a lower fidelity than a Fock state input, for the same photon number.Comment: 4 pages, 3 figure

    Automated Academic and Professional Behaviors Student Tracking Systems

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    The purpose of this presentation is to describe a novel program faculty designed automated academic and professional behaviors student tracking system in select programs at three campuses of the University of St Augustine for Health Sciences. The automated tracking systems streamlined and served to improve both faculty and student understanding of both academic and professional behavior performance, across three programs and three campuses at this multi campus university Early detection of performance insufficiencies was critical to changing performance and behavior

    Partners in Water Quality Monitoring at Mammoth Cave National Park, Kentucky

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    Water resources are essential to landscape development and maintenance of the extraordinary ecosystem at Mammoth Cave National Park, Kentucky. The National Park Service has implemented many policies and management practices in an effort to maintain and improve the water quality in the park. As part of their resources management, the Park evaluates current hydrologic conditions, as well as, anticipates and responds to emerging issues. With regards to that goal, Mammoth Cave National Park Service partnered with Tennessee State University, the Mammoth Cave International Center for Science and Learning, and the U.S. Geological Survey on a series of water-related projects from 2007-2013. The objective of this paper is to highlight some of the findings and lessons learned from the past 6 years. Many of the results presented in this paper have been presented at other conferences or published in other reports. Collaborative projects included storm-water runoff from parking lots and roads, evaluating storm-water filters, and transport of chemicals in the caves. These projects purposefully engaged students to provide professional experience and educational outreach opportunities. Over 50 student presentations related to these monitoring activities have been made at regional and national conferences in the past 6 years, resulting in numerous awards and publications. Major funding or in-kind services were provided by the partnering agencies and institutions. Additional funding for supplies and student support was provided by the National Science Foundation (Opportunity for Enhancing Diversity in Geoscience, 2007-8; Undergraduate Research and Mentoring, 2009-13), and, the Department of Energy (Massey Chair – NNSA, 2007-13). The following summaries are excerpts from previously published student papers (West et al., 2010; Diehl et al., 2012, Embry, et al., 2012, West et al., 2012)

    Evidence of Titan's Climate History from Evaporite Distribution

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    Water-ice-poor, 5-μ\mum-bright material on Saturn's moon Titan has previously been geomorphologically identified as evaporitic. Here we present a global distribution of the occurrences of the 5-μ\mum-bright spectral unit, identified with Cassini's Visual Infrared Mapping Spectrometer (VIMS) and examined with RADAR when possible. We explore the possibility that each of these occurrences are evaporite deposits. The 5-μ\mum-bright material covers 1\% of Titan's surface and is not limited to the poles (the only regions with extensive, long-lived surface liquid). We find the greatest areal concentration to be in the equatorial basins Tui Regio and Hotei Regio. Our interpretations, based on the correlation between 5-μ\mum-bright material and lakebeds, imply that there was enough liquid present at some time to create the observed 5-μ\mum-bright material. We address the climate implications surrounding a lack of evaporitic material at the south polar basins: if the south pole basins were filled at some point in the past, then where is the evaporite

    Measuring Information Transfer

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    An information theoretic measure is derived that quantifies the statistical coherence between systems evolving in time. The standard time delayed mutual information fails to distinguish information that is actually exchanged from shared information due to common history and input signals. In our new approach, these influences are excluded by appropriate conditioning of transition probabilities. The resulting transfer entropy is able to distinguish driving and responding elements and to detect asymmetry in the coupling of subsystems.Comment: 4 pages, 4 Figures, Revte

    What is a clinical pathway? Refinement of an operational definition to identify clinical pathway studies for a Cochrane systematic review

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    Clinical pathways (CPWs) are a common component in the quest to improve the quality of health. CPWs are used to reduce variation, improve quality of care, and maximize the outcomes for specific groups of patients. An ongoing challenge is the operationalization of a definition of CPW in healthcare. This may be attributable to both the differences in definition and a lack of conceptualization in the field of clinical pathways. This correspondence article describes a process of refinement of an operational definition for CPW research and proposes an operational definition for the future syntheses of CPWs literature. Following the approach proposed by Kinsman et al. (BMC Medicine 8(1):31, 2010) and Wieland et al. (Alternative Therapies in Health and Medicine 17(2):50, 2011), we used a four-stage process to generate a five criteria checklist for the definition of CPWs. We refined the operational definition, through consensus, merging two of the checklist’s criteria, leading to a more inclusive criterion for accommodating CPW studies conducted in various healthcare settings. The following four criteria for CPW operational definition, derived from the refinement process described above, are (1) the intervention was a structured multidisciplinary plan of care; (2) the intervention was used to translate guidelines or evidence into local structures; (3) the intervention detailed the steps in a course of treatment or care in a plan, pathway, algorithm, guideline, protocol or other ‘inventory of actions’ (i.e. the intervention had time-frames or criteria-based progression); and (4) the intervention aimed to standardize care for a specific population. An intervention meeting all four criteria was considered to be a CPW. The development of operational definitions for complex interventions is a useful approach to appraise and synthesize evidence for policy development and quality improvement
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