7,553 research outputs found

    Estimating Environmental Benefits of Natural Hazard Mitigation with Benefit Transfer: Results from a Benefit-Cost Analysis of FEMA Hazard Mitigation Grants

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    This paper summarizes methods, data, and results associated with the first major attempt to evaluate the environmental benefits of FEMA natural hazards mitigation grants. The study relied heavily on the refinement of benefit transfer methods. Categories of benefits include water quality for recreational and commercial fishing, drinking water, outdoor recreation, hazardous waste, wetlands and aesthetic, health and safety benefits. Environmental and historic benefits proved to be a very minor proportion of the total benefits in dollar terms. Only a very small percentage of earthquake and wind-related hazards yielded environmental benefits, while a sizeable percentage of flood hazard grants did so. We also discuss the prospects that environmental benefits might have been much greater had data been available to analyze more environmental impacts. Key Words: Natural Hazard Mitigation, Environmental Benefits

    Constructing Efficient Choice Experiments

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    Research on the construction of efficient designs for stated choice (SC) experiments has been limited to either unlabeled experiments with generic parameter estimates or labeled experiments with alternative specific parameter estimates. Designs combining both generic and alternative specific parameters have not yet been addressed. In this paper, by deriving the asymptotic (co)variance matrix for the most general MNL model, the authors are able to demonstrate how efficient experiments that allow for the estimation of both types of estimates may be generated. The authors go onto show how estimation of the asymptotic (co)variance matrix may also be used to determine sample size requirements for SC experiments

    Paleoepidemiology of Infectious Disease in the Dickson Mounds Population

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    The major focus of paleopathology has been the delimiting of disease in time and space. Information about the history of specific diseases is the objective of many of these studies. While the chronological and geographical dimensions of paleopathology contribute significantly to our knowledge of disease, there are limits to this approach, which often fails to consider the interaction of biology and culture in the disease of prehistoric populations

    Approximation of Bayesian Efficiency in Experimental Choice Designs

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    This paper compares different types of simulated draws over a range of number of draws in generating Bayesian efficient designs for stated choice studies. The paper examines how closely pseudo Monte Carlo, quasi Monte Carlo and polynomial cubature methods are able to replicate the true levels of Bayesian efficiency for SC designs of various dimensions. The authors conclude that the predominantly employed method of using pseudo Monte Carlo draws is unlikely to result in leading to truly Bayesian efficient SC designs. The quasi Monte Carlo methods analyzed here (Halton, Sobol, and Modified Latin Hypercube Sampling) all clearly outperform the pseudo Monte Carlo draws. However, the polynomial cubature method examined in this paper, incremental Gaussian quadrature, outperforms all, and is therefore the recommended approximation method for the calculation of Bayesian efficiency of stated choice designs

    A new method for imaging nuclear threats using cosmic ray muons

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    Muon tomography is a technique that uses cosmic ray muons to generate three dimensional images of volumes using information contained in the Coulomb scattering of the muons. Advantages of this technique are the ability of cosmic rays to penetrate significant overburden and the absence of any additional dose delivered to subjects under study above the natural cosmic ray flux. Disadvantages include the relatively long exposure times and poor position resolution and complex algorithms needed for reconstruction. Here we demonstrate a new method for obtaining improved position resolution and statistical precision for objects with spherical symmetry

    Maximum Power Efficiency and Criticality in Random Boolean Networks

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    Random Boolean networks are models of disordered causal systems that can occur in cells and the biosphere. These are open thermodynamic systems exhibiting a flow of energy that is dissipated at a finite rate. Life does work to acquire more energy, then uses the available energy it has gained to perform more work. It is plausible that natural selection has optimized many biological systems for power efficiency: useful power generated per unit fuel. In this letter we begin to investigate these questions for random Boolean networks using Landauer's erasure principle, which defines a minimum entropy cost for bit erasure. We show that critical Boolean networks maximize available power efficiency, which requires that the system have a finite displacement from equilibrium. Our initial results may extend to more realistic models for cells and ecosystems.Comment: 4 pages RevTeX, 1 figure in .eps format. Comments welcome, v2: minor clarifications added, conclusions unchanged. v3: paper rewritten to clarify it; conclusions unchange

    Time-Gating of Pulsed Eddy Current Signals for Defect Characterization and Discrimination in Aircraft Lap-Joints

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    Pulsed eddy current (PEC) nondestructive testing differs from conventional eddy current techniques in that the probe coil is excited by a pulse, rather than continuous excitation at a single frequency. Reviews of early work on pulsed eddy currents are given by Waidelich1 and by Renkin.2 Pulsed excitation causes the propagation of a highly attenuated traveling wave, which is governed by the diffusion equation.3 The diffusive propagation of the eddy current pulse results in spatial broadening and a delay, or travel time, proportional to the square of the distance traveled. It was realized in early work on pulsed eddy current systems that this time dependence offered certain advantages over conventional eddy currents.4 In the current study we demonstrate the ability of a prototype pulsed eddy current instrument, described elsewhere,5,6 to take advantage of this time dependence to discriminate flaws from such interfering signals as probe liftoff, air gaps, and fasteners

    Direct and cross elasticities for freight distribution access charges

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    The interest in reform of road user charges for freight distribution in many countries continues unabated, linked to a desire to improve economic efficiency as well as recognition of the declining revenue base from traditional sources, especially fuel excise. A critical input into the assessment framework used to identify the impact of alternative access charges on freight vehicle utilisation, by vehicle class, is a suite of direct and cross elasticities. This paper uses data collected in Australia in 2010- 11 on alternative access charge regimes obtained from a stated choice experiment, used in estimation of mixed logit models calibrated on vehicle market shares, to derive matrices of direct and cross access charging elasticities that represent the relationship between an access charge (defined by combinations of distance, mass, and location), vehicle class choice, total kilometres, and tonne-kilometres carried in the vehicle class segments. The elasticities can be used to estimate the response of heavy vehicle operators (and shippers) to price signals under the different access charging schemes

    Particle fallout/activity sensor

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    A particle fallout/activity sensor measures relative amounts of dust or other particles which collect on a mirror in an area to be monitored. The sensor includes a sensor module and a data acquisition module, both of which can be operated independently of one another or in combination with one another. The sensor module includes a housing containing the mirror, an LED assembly for illuminating the mirror and an optical detector assembly for detecting light scattered off of the mirror by dust or other particles collected thereon. A microprocessor controls operation of the sensor module's components and displays results of a measurement on an LCD display mounted on the housing. A push button switch is also mounted on the housing which permits manual initiation of a measurement. The housing is constructed of light absorbing material, such as black delrin, which minimizes detection of light by the optical detector assembly other than that scattered by dust or particles on the mirror. The data acquisition module can be connected to the sensor module and includes its own microprocessor, a timekeeper and other digital circuitry for causing the sensor module to make a measurement periodically and send the measurement data to the data acquisition module for display and storage in memory for later retrieval and transfer to a separate computer. The time tagged measurement data can also be used to determine the relative level of activity in the monitored area since this level is directly related to the amount of dust or particle fallout in the area

    Stacked Tracking for CMS at Super-LHC

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    We report recent work on the design of a pixel detector for CMS at the Super-LHC. This work builds on previous studies of a tracking detector capable of providing track stubs to be used in the Level-1 Trigger (L1T). We now focus on the use of two ‘superlayers’ of tracking; each comprising a pair of pixel sensors with 50×50×50μm3 pitch (z×φ×r) separated by a few millimetres. Preliminary work on track reconstruction in Field Programmable Gate Arrays (FPGAs) is also presented
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