3,147 research outputs found

    Thriving Arts: Thriving Small Communities

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    Presents findings from a study of ten rural Minnesota communities to identify factors related to successful community arts development. Includes recommendations to inform future investment in the arts

    Star formation and spiral structure in M81

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    High resolution digitized images of M81 in the radio continuum, H alpha, H I, and I band are used to see how well various density wave models agree in detail with observations. It was found that the observed width of the nonthermal radio arms favors a cloudy version of a density wave model. The radial distribution of the set of giant radio H II regions disagrees with the simple expression of Shu and Visser for star formation by a density wave. The observed displacements of the giant radio H II regions from the spiral velocity shock indicate that some revisions in the details of the ballistic particle model of Leisawitz and Bash are necessary

    Fundamental limits of quantum-secure covert optical sensing

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    We present a square root law for active sensing of phase θ\theta of a single pixel using optical probes that pass through a single-mode lossy thermal-noise bosonic channel. Specifically, we show that, when the sensor uses an nn-mode covert optical probe, the mean squared error (MSE) of the resulting estimator θ^n\hat{\theta}_n scales as (θθ^n)2=O(1/n)\langle (\theta-\hat{\theta}_n)^2\rangle=\mathcal{O}(1/\sqrt{n}); improving the scaling necessarily leads to detection by the adversary with high probability. We fully characterize this limit and show that it is achievable using laser light illumination and a heterodyne receiver, even when the adversary captures every photon that does not return to the sensor and performs arbitrarily complex measurement as permitted by the laws of quantum mechanics.Comment: 13 pages, 1 figure, submitted to ISIT 201

    Bounding the quantum limits of precision for phase estimation with loss and thermal noise

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    We consider the problem of estimating an unknown but constant carrier phase modulation θ\theta using a general -- possibly entangled -- nn-mode optical probe through nn independent and identical uses of a lossy bosonic channel with additive thermal noise. We find an upper bound to the quantum Fisher information (QFI) of estimating θ\theta as a function of nn, the mean and variance of the total number of photons NSN_{\rm S} in the nn-mode probe, the transmissivity η\eta and mean thermal photon number per mode nˉB{\bar n}_{\rm B} of the bosonic channel. Since the inverse of QFI provides a lower bound to the mean-squared error (MSE) of an unbiased estimator θ~\tilde{\theta} of θ\theta, our upper bound to the QFI provides a lower bound to the MSE. It already has found use in proving fundamental limits of covert sensing, and could find other applications requiring bounding the fundamental limits of sensing an unknown parameter embedded in a correlated field.Comment: No major changes to previous version. Change in the title and abstract, change in the presentation and structure, an example of the bound is now included, and some references were added. Comments are welcom

    Covert sensing using floodlight illumination

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    We propose a scheme for covert active sensing using floodlight illumination from a THz-bandwidth amplified spontaneous emission (ASE) source and heterodyne detection. We evaluate the quantum-estimation-theoretic performance limit of covert sensing, wherein a transmitter's attempt to sense a target phase is kept undetectable to a quantum-equipped passive adversary, by hiding the signal photons under the thermal noise floor. Despite the quantum state of each mode of the ASE source being mixed (thermal), and hence inferior compared to the pure coherent state of a laser mode, the thousand-times higher optical bandwidth of the ASE source results in achieving a substantially superior performance compared to a narrowband laser source by allowing the probe light to be spread over many more orthogonal temporal modes within a given integration time. Even though our analysis is restricted to single-mode phase sensing, this system could be applicable extendible for various practical optical sensing applications.Comment: We present new results and discuss some results found in arXiv:1701.06206. Comments are welcom

    EVALUATING OPTIMAL PRODUCT MIX USING DYNAMIC SIMULATION: A TOMATO PROCESSING CASE

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    Technology-driven change is everywhere and value-capture from new technology is challenging for business managers. Also rival firms may use technology as part of major success strategies. This situation leads managers to be keenly interested in evaluation of alternative technologies prior to making a sunk investment in physical facilities. In contemplating new or added-capacity processing facilities, managers and investors must evaluate return on investment (ROI). Evaluation of ROI is complex because it varies by alternative technology and the resultant potential product mix alternatives associated with that technology at the time the investment capital is committed to build the processing plant. This research examines optimal alternative product mix from a processing plant technology that is fixed at the time of commitment to building or adding capacity. Evaluating the optimal product mix is of vital concern in any start-up processing environment. In this research the optimal product mix is evaluated by using a sophisticated evaluative tool known as PowerSim. This economic simulation software is used to model a start-up tomato processing plant in Ohio. The model evaluates the effects of various output, or tomato product mix, on plant profitability measured by ROI. Results indicate that an increase in plant profitability is expected when the tomato product mix consists of products that have a lower soluble solids concentration. The lower the soluble solids concentration of a tomato product, the less the processor will benefit from tomato varieties with high soluble solids. The processing operation achieves a RIO of 26.5 percent when the plant'Â’s product mix is 50 percent tomato paste (31 degrees brix) and 50 percent diced tomatoes. This product mix optimizes processor net income and realizes a plant return on equity of 50.6 percent.Agribusiness,

    The molecular basis of T cell acute lymphoblastic leukemia

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    T cell acute lymphoblastic leukemias (T-ALLs) arise from the malignant transformation of hematopoietic progenitors primed toward T cell development, as result of a multistep oncogenic process involving constitutive activation of NOTCH signaling and genetic alterations in transcription factors, signaling oncogenes, and tumor suppressors. Notably, these genetic alterations define distinct molecular groups of T-ALL with specific gene expression signatures and clinicobiological features. This review summarizes recent advances in our understanding of the molecular genetics of T-ALL
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