13,070 research outputs found

    Foundation Support for Nonprofit Capital Needs in Southern California

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    Analyzes trends in foundation funding for nonprofits' capital campaigns, land acquisition, and building and renovation in five counties. Lists foundations that may provide capital support, but suggests securing other primary sources of capital funding

    Optimizing Forecasting Methods for USTRANSCOM Railcar Demands

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    The United States military heavily relies on rail freight operations to meet many of its logistical needs during both peacetime and wartime efforts. As the head organization responsible for managing and overseeing all modes of military transportation, United States Transportation Command depends on timely accurate railcar demand forecasts to drive critical decisions on distribution and placement of railcar assets. However, the intermittent nature of railcar demands based on location and commodity make it a challenging task for forecasters. Furthermore, these “lumpy” demands often come without any obvious trends or seasonality. This study explores the utility of both traditional forecasting methods and newer techniques designed specifically for handling intermittent demands. All forecasting parameters for each method are optimized based on specific cost functions. Accuracy metrics are then applied to all forecasts for analysis. The results indicate that for the Department of Defense’s railcar demands, optimizing basic forecasting methods such as Simple Moving Averages and Simple Exponential Smoothing outperform more popular methods for sparse demands such as Croston’s method and its variants. Despite its theoretical superiority, applying Croston’s method to railcar demands was found questionable and consistently produced poor forecasts compared to other methods. Analysis provides valuable insight in future strategies for forecasting intermittent demands

    Measuring the Contribution of Water and Green Space Amenities to Housing Values: An Application and Comparison of Spatially-weighted Hedonic Models

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    This study estimates the influence of proximity to water bodies and park amenities on residential housing values in Knox County, Tennessee, using the hedonic price approach. Values for proximity to water bodies and parks are first estimated globally with a standard ordinary least square (OLS) model. A locally weighted regression model is then employed to investigate spatial non-stationarity and generate local estimates for individual sources of each amenity. The local model is able to capture the variability in the quality of water bodies and parks across the county, something a conventional hedonic model using OLS cannot do.Land Economics/Use,

    Stratospheric measurements of continuous absorption near 2400 cm^-1

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    Solar occultation spectra obtained with a balloon-borne interferometer have been used to study continuous absorption by N2 and CO2 near 2400 cm^-1 in the lower stratosphere. Synthetic continuum transmittances, calculated from published coefficients for far-wing absorption by CO2 lines and for pressure-induced absorption by the fundamental band of N2, are in fair agreement with the observed stratospheric values. The continuum close to the ν3 R-branch band head of CO2 is sensitive to the CO2 far-wing line shape. Therefore, given highly accurate knowledge of the N2 continuum from laboratory data, high-resolution stratospheric spectra provide a sensitive means for in situ testing of various air-broadened CO2 line shapes at low temperatures

    Evidence of Energetic Optimization during Adaptation Differs for Metabolic, Mechanical, and Perceptual Estimates of Energetic Cost

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    The theory that the sensorimotor system minimizes energetic cost during locomotion has long been supported by both computational models and empirical studies. However, it has yet to be determined if the behavior to which people converge when exposed to a novel perturbation during locomotion is also energetically optimal. We address this issue in the context of adaptation to walking on a split-belt treadmill, which can impose a left-right asymmetry in step lengths. In response to this asymmetry, participants gradually adjust their foot placement to adopt steps of equal length. Here, we characterized metabolic, mechanical, and perceptual estimates of energetic cost associated with a range of asymmetries to determine whether symmetry is the energetically optimal strategy for walking on a split-belt treadmill. We found that taking steps of equal length did not minimize metabolic cost or mechanical cost. In addition, perceptual estimates of cost were not sensitive to changes in asymmetry. However, symmetry was identified as the optimal strategy when energetic cost was estimated from a composite metric that combined both metabolic and mechanical costs. These results suggest that adaptation may arise from optimization of a composite estimate of effort derived from feedback about the interaction between the body and environment

    Surgical Resection in HCC

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    Hepatocellular carcinoma (HCC) is a deadly disease. Its incidence is rising worldwide without significant improvement in survival in spite of improving therapies. A wide array of treatment options for HCC exist and include surgery, catheter-based therapies, radiation and systemic therapy. These modalities are often used in combination for optimal management in a multidisciplinary approach. Surgical resection remains one of the only curative therapeutic options for HCC, although it is indicated in select patients with localized disease. Herein, we cover the role of surgical resection in the management of HCC, reviewing the perioperative and operative considerations, in addition to highlighting the advances in minimally invasive surgery and novel navigation technologies

    The one-loop six-dimensional hexagon integral with three massive corners

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    We compute the six-dimensional hexagon integral with three non-adjacent external masses analytically. After a simple rescaling, it is given by a function of six dual conformally invariant cross-ratios. The result can be expressed as a sum of 24 terms involving only one basic function, which is a simple linear combination of logarithms, dilogarithms, and trilogarithms of uniform degree three transcendentality. Our method uses differential equations to determine the symbol of the function, and an algorithm to reconstruct the latter from its symbol. It is known that six-dimensional hexagon integrals are closely related to scattering amplitudes in N=4 super Yang-Mills theory, and we therefore expect our result to be helpful for understanding the structure of scattering amplitudes in this theory, in particular at two loops.Comment: 15 pages, 2 figure

    Trick or Heat? Manipulating Critical Temperature-Based Control Systems Using Rectification Attacks

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    Temperature sensing and control systems are widely used in the closed-loop control of critical processes such as maintaining the thermal stability of patients, or in alarm systems for detecting temperature-related hazards. However, the security of these systems has yet to be completely explored, leaving potential attack surfaces that can be exploited to take control over critical systems. In this paper we investigate the reliability of temperature-based control systems from a security and safety perspective. We show how unexpected consequences and safety risks can be induced by physical-level attacks on analog temperature sensing components. For instance, we demonstrate that an adversary could remotely manipulate the temperature sensor measurements of an infant incubator to cause potential safety issues, without tampering with the victim system or triggering automatic temperature alarms. This attack exploits the unintended rectification effect that can be induced in operational and instrumentation amplifiers to control the sensor output, tricking the internal control loop of the victim system to heat up or cool down. Furthermore, we show how the exploit of this hardware-level vulnerability could affect different classes of analog sensors that share similar signal conditioning processes. Our experimental results indicate that conventional defenses commonly deployed in these systems are not sufficient to mitigate the threat, so we propose a prototype design of a low-cost anomaly detector for critical applications to ensure the integrity of temperature sensor signals.Comment: Accepted at the ACM Conference on Computer and Communications Security (CCS), 201
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