2,968 research outputs found

    On reduction of differential inclusions and Lyapunov stability

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    In this paper, locally Lipschitz, regular functions are utilized to identify and remove infeasible directions from set-valued maps that define differential inclusions. The resulting reduced set-valued map is point-wise smaller (in the sense of set containment) than the original set-valued map. The corresponding reduced differential inclusion, defined by the reduced set-valued map, is utilized to develop a generalized notion of a derivative for locally Lipschitz candidate Lyapunov functions in the direction(s) of a set-valued map. The developed generalized derivative yields less conservative statements of Lyapunov stability theorems, invariance theorems, invariance-like results, and Matrosov theorems for differential inclusions. Included illustrative examples demonstrate the utility of the developed theory

    EXPANDING THE NATIONAL FLOOD INSURANCE PROGRAM TO COVER COASTAL EROSION DAMAGE

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    The National Flood Insurance Program does not currently cover damage strictly attributable to coastal erosion. This paper uses the results of a nationwide survey of coastal property owners to estimate the demand for such insurance. We find that there is significant demand at prices in the range of current flood insurance premiums. Demand is influenced in the hypothesized way by increased measures of erosion risk as well as by insurance price and income.Land Economics/Use, Risk and Uncertainty,

    AN ECONOMIC EVALUATION OF BEACH EROSION MANAGEMENT ALTERNATIVES

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    This paper examines the relative economic efficiency of three distinct beach erosion management policies — beach nourishment with shoreline armoring, beach nourishment without armoring, and shoreline retreat. The analysis focuses on (i) the recreational benefits of beaches, (ii) the property value effects of beach management, and (iii) the costs associated with the three management scenarios. Assuming the removal of shoreline armoring improves overall beach quality, beach nourishment with shoreline armoring is the least desirable of the three alternatives. The countervailing property losses under a retreat strategy are of the same order of magnitude as the foregone management costs when the beneficial effects of retreat — higher values of housing services for those houses not lost to erosion — are considered. The relative desirability of these alternative strategies depends upon the realized erosion rate and how management costs change over time.Resource /Energy Economics and Policy,

    COSTS OF COASTAL HAZARDS: EVIDENCE FROM THE PROPERTY MARKET

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    A hedonic price model suggests that flooding and erosion hazards, and the actions taken against them, are major determinants of property values in American coastal areas. A zoning ordnance against new construction within the 60-year erosion hazard area would increase property values and perhaps conserve the coastal ecosystem.Environmental Economics and Policy, Land Economics/Use,

    Prominent crista terminalis in a fetus

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    Background: The crista terminalis is a normal cardiac structure located in the right atrium. It is not usually seen using standard view transthoracic echocardiography techniques, but on occasion, hypertrophy allows for easy visualization of this structure, which can be mistakenly labelled pathologic. Case: We report the first known case of a prominent crista terminalis detected in a fetus. Conclusions: This case confirms the presence of a prominent crista terminalis in a developing fetus, a variant which was exclusively described in the pediatric and adult populations until now. Although a prominent crista terminalis is a benign variant, the correct identification of this structure has important diagnostic implications. This report aims to increase familiarity with the appearance of a prominent crista terminalis on both fetal echocardiography and newborn transthoracic echocardiography in hopes that this will aid in the correct diagnosis of this variant in the future.peer-reviewe

    Evaluation of Apparent Life-Threatening Events in Infants

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    A comprehensive, detailed history and physical examination with pulse oximetry and nondilated funduscopy (to look for traumatic retinal hemorrhage) helps to determine the underlying etiology of an apparent life-threatening event (ALTE) in 70 percent of infants. (Strength of Recommendation [SOR]: C, based on case series). Initial diagnostic evaluation should include 12-lead electrocardiography (ECG); blood gas analysis; chest radiography; complete blood count (CBC); pertussis and respiratory syncytial virus cultures, if respiratory symptoms are present; serum electrolytes; and urinalysis. (SOR: C, expert opinion and case series)

    The Effects of Evening Bright Light Exposure on Subsequent Morning Exercise Performance

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    We investigated the effects of evening bright light on the circadian timing of core temperature and morning exercise performance under conditions of high thermal stress. At 20:00 h, 8 males were exposed to a standardised light protocol and thereafter to either polychromatic bright light (2 500 lux at 50 cm, BL) or no light (0 lux, NL) for 30 min. The following morning, intermittent cycling exercise was undertaken followed by a 10 km time-trial in an environmental chamber set to 35°C and 60% relative humidity. Core body temperature was measured throughout. Data were analysed using a within-subjects model and presented as mean±SD. Time of the sleep-trough in core temperature occurred ~1.75 h later following BL (P=0.07). Prior to time-trial, core temperature was 0.27±0.42°C lower in BL (95%CI: −0.02 to 0.57, P=0.07). The time-trial was completed 1.43±0.63 min (0.98–1.87) faster in BL (P=0.001). Post time-trial, intestinal temperature was 38.21±0.56°C (37.84–38.57) in BL compared to 38.64±0.42°C (38.34–38.93) in NL (P=0.10). These data provide the first evidence that a 30-min exposure to bright light prior to sleep can influence exercise performance under hot conditions during the subsequent early morning

    Screening properties of Gaussian electrolyte models, with application to dissipative particle dynamics

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    We investigate the screening properties of Gaussian charge models of electrolyte solutions by analysing the asymptotic behaviour of the pair distribution functions. We use a combination of Monte-Carlo simulations with the hyper-netted chain integral equation closure, and the random phase approximation, to establish the conditions under which a screening length is well defined and the extent to which it matches the expected Debye length. For practical applications, for example in dissipative particle dynamics, we are able to summarise our results in succinct rules-of-thumb which can be used for mesoscale modeling of electrolyte solutions. We thereby establish a solid foundation for future work, such as the systematic incorporation of specific ion effects.Comment: 9 pages, 9 figures, 1 table, RevTeX4-

    Initial test results on bolometers for the Planck high frequency instrument

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    We summarize the fabrication, flight qualification, and dark performance of bolometers completed at the Jet Propulsion Laboratory for the High Frequency Instrument (HFI) of the joint ESA/NASA Herschel/Planck mission to be launched in 2009. The HFI is a multicolor focal plane which consists of 52 bolometers operated at 100 mK. Each bolometer is mounted to a feedhorn-filter assembly which defines one of six frequency bands centered between 100-857 GHz. Four detectors in each of five bands from 143-857 GHz are coupled to both linear polarizations and thus measure the total intensity. In addition, eight detectors in each of four bands (100, 143, 217, and 353 GHz) couple only to a single linear polarization and thus provide measurements of the Stokes parameters, Q and U, as well as the total intensity. The measured noise equivalent power (NEP) of all detectors is at or below the background limit for the telescope and time constants are a few ms, short enough to resolve point sources as the 5 to 9 arc min beams move across the sky at 1 rpm

    Apple pollination investigations

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    Publication authorized March 18, 1930.Includes bibliographical references (pages 35-36)
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