39,029 research outputs found

    Preparing Low-Skilled Workers for the Jobs of Tomorrow

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    Identifies ways for state policies to leverage technology-based economic development by preparing low-skilled workers for middle-skill, technical jobs in the fields of science, technology, engineering, and math (STEM). Outlines current state initiatives

    Lessons from the crisis

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    A lot happened even before the perceived beginning of this crisis in 2007, so although the events are recent, I will give an overview from a US perspective of the period from 2001 to date, in our search for the lessons to be learned. Much of it is probably familiar, but worth revisiting. I will break this necessarily simplified account into 3 stages: first, a look at the key factors that led to the increasing riskiness of US home mortgages; second, how those risks were transmitted as securities from US housing lenders to institutional investors around the globe; and third, how those risks led to huge losses and created a credit crunch that moved the impact from the financial economy to the real economy and produced a severe recession. Then we will have a factual foundation for deriving the lessons that ought to be taken away from this very expensive experience

    Lorentzian Iterative Hard Thresholding: Robust Compressed Sensing with Prior Information

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    Commonly employed reconstruction algorithms in compressed sensing (CS) use the L2L_2 norm as the metric for the residual error. However, it is well-known that least squares (LS) based estimators are highly sensitive to outliers present in the measurement vector leading to a poor performance when the noise no longer follows the Gaussian assumption but, instead, is better characterized by heavier-than-Gaussian tailed distributions. In this paper, we propose a robust iterative hard Thresholding (IHT) algorithm for reconstructing sparse signals in the presence of impulsive noise. To address this problem, we use a Lorentzian cost function instead of the L2L_2 cost function employed by the traditional IHT algorithm. We also modify the algorithm to incorporate prior signal information in the recovery process. Specifically, we study the case of CS with partially known support. The proposed algorithm is a fast method with computational load comparable to the LS based IHT, whilst having the advantage of robustness against heavy-tailed impulsive noise. Sufficient conditions for stability are studied and a reconstruction error bound is derived. We also derive sufficient conditions for stable sparse signal recovery with partially known support. Theoretical analysis shows that including prior support information relaxes the conditions for successful reconstruction. Simulation results demonstrate that the Lorentzian-based IHT algorithm significantly outperform commonly employed sparse reconstruction techniques in impulsive environments, while providing comparable performance in less demanding, light-tailed environments. Numerical results also demonstrate that the partially known support inclusion improves the performance of the proposed algorithm, thereby requiring fewer samples to yield an approximate reconstruction.Comment: 28 pages, 9 figures, accepted in IEEE Transactions on Signal Processin

    The effect of small variations in profile of airfoils

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    This report deals with the effect of small variations in ordinates specified by different laboratories for the airfoil section. This study was made in connection with a more general investigation of the effect of small irregularities of the airfoil surface on the aerodynamic characteristics of an airfoil. These tests show that small changes in airfoil contours, resulting from variations in the specified ordinates, have a sufficiently large effect upon the airfoil characteristics to justify the taking of great care in the specification of ordinates for the construction of models

    The Interference Effects on an Airfoil of a Flat Plate at Mid-span Position

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    This report gives the results of an investigation of the mutual interference of an airfoil and a flat plate inserted at mid-span position. The tests were conducted in the Variable-Density Wind Tunnel of the National Advisory Committee for Aeronautics at a high value of the Reynolds Number. The interference effects of this combination were found to be small. Supplementary tests indicated that the use of fillets decreases both the lift and drag slightly. A bibliography of publication dealing with interference between wings and bodies, and with the effects of cut-outs and fillets is included

    Treatment Decision-Making in Catastrophic Illness

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    It is well established that the social and economic environment of medical care distinguishes its provision from that of other goods and services. While scholars have studied the influences of this idiosyncratic environment, there is relatively little empirical knowledge about how it affects decision-making in specific medical contexts. Through general conceptual discussion and consideration of a case study of leukemia chemo-therapy, this paper examines the medical decision-making process in one specific context: the response of physicians to the availability of an innovative treatment for a catastrophic illness. The manner in which the medical profession deals with serious illness is relevant to concerns as diverse as the promotion of economic efficiency and the preservation of human dignity.

    THE MORAL ENVIRONMENT OF PUBLIC POLICY

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    Public Economics,
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