4,299 research outputs found

    Suggested hurricane operational scenario for GOES I-M

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    Improvements in tropical cyclone forecasts require optimum use of remote sensing capabilities, because conventional data sources cannot provide the necessary spatial and temporal data density over tropical and subtropical oceanic regions. In 1989, the first of a series of geostationary weather satellites, GOES 1-M, will be launched with the capability for simultaneous imaging and sounding. Careful scheduling of the GOES 1-M will enable measurements of both the wind and mass fields over the entire tropical cyclone activity area. The document briefly describes the GOES 1-M imager and sounder, surveys the data needs for hurricane forecasting, discusses how geostationary satellite observations help to meet them, and proposes a GOES 1-M schedule of observations and hurricane relevant derived products

    How linear features alter predator movement and the functional\ud response

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    In areas of oil and gas exploration, seismic lines have been reported to alter the movement patterns of wolves (Canis lupus). We developed a mechanistic first passage time model, based on an anisotropic elliptic partial differential equation, and used this to explore how wolf movement responses to seismic lines influence the encounter rate of the wolves with their prey. The model was parametrized using 5 min GPS location data. These data showed that wolves travelled faster on seismic lines and had a higher probability of staying on a seismic line once they were on it. We simulated wolf movement on a range of seismic line densities and drew implications for the rate of predator–prey interactions as described by the functional response. The functional response exhibited a more than linear increase with respect to prey density (type III) as well as interactions with seismic line density. Encounter rates were significantly higher in landscapes with high seismic line density and were most pronounced at low prey densities. This suggests that prey at low population densities are at higher risk in environments with a high seismic line density unless they learn to avoid them

    Development of a scale to assess avoidance behavior due to a fear of falling: the fear of falling avoidance behavior questionnaire

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    Journal ArticleBackground. A history of falls or imbalance may lead to a fear of falling, which may lead to self-imposed avoidance of activity; this avoidance may stimulate a vicious cycle of deconditioning and subsequent falls. Objective. The purpose of this study was to develop a questionnaire that would quantify avoidance behavior due to a fear of falling. Design. This study consisted of 2 parts: questionnaire development and psychometric testing. Questionnaire development involved an expert panel and 39 residents of an assisted living facility. Sixty-three community-dwelling individuals with various health conditions participated in psychometric testing. Method. Questionnaire development included the evaluation of face and content validity and factor analysis of the initial questionnaire. The final result of questionnaire development was the Fear of Falling Avoidance Behavior Questionnaire (FFABQ). In order to determine its psychometric properties, reliability and construct validity were assessed through administration of the FFABQ to participants twice, 1 week apart, and comparison of the FFABQ with other questionnaires related to fear of falling, functional measures of balance and mobility, and daily activity levels using an activity monitor. Results. The FFABQ had good overall test-retest reliability (intraclass correlation coefficient=.812) and was found to differentiate between participants who were considered ?fallers? (ie, at least one fall in the previous year) and those who were considered ?nonfallers.? The FFABQ predicted time spent sitting or lying and endurance. Limitations. A relatively small number of people with a fear of falling were willing to participate. Conclusion. Results from this study offer evidence for the reliability and validity of the FFABQ and support the notion that the FFABQ measures avoidance behavior rather than balance confidence, self-efficacy, or fear

    Many-Body Electrostatic Forces Between Colloidal Particles at Vanishing Ionic Strength

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    Electrostatic forces between small groups of colloidal particles are measured using blinking optical tweezers. When the electrostatic screening length is significantly larger than the particle radius, forces are found to be non-pairwise additive. Both pair and multi-particle forces are well described by the linearized Poisson-Boltzmann equation with constant potential boundary conditions. These findings may play an important role in understanding the structure and stability of a wide variety of systems, from micron-sized particles in oil to aqueous nanocolloids.Comment: 5 pages 2 figure

    HYTESS: A hypothetical turbofan engine simplified simulation

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    A users manual for a hypothetical turbofan engine simplified simulation is presented. This digital simulation exists as FORTRAN source code. The program is self-contained and was developed to offer those interested in engine dynamics and controls research an efficient, realistic, and easily used engine simulation. The engine is modeled using a state space formulation. Matrix elements within the linear state space structure are nonlinear functions of various engine variables

    Some Model Amendments to Maine (and other States\u27) Land Use Control Legislation

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    This model legislation consisting of ten separate provisions is intended to clarify and/or expand existing Maine law dealing with planning and land use regulation. It expands existing statutes by addressing a number of issues not presently covered by law. The overarching purpose of the proposed legislation is to underscore that planning and the imposition of land use regulations is not exclusively the responsibility of local governments but instead is a shared duty of the state and local governments. This is clearly stated in the text and commentary of Provision I, and is a theme that pervades all ten legislative proposals. Secondarily, Provision I and those that follow make clear that it is the State with its resources and larger geographical reach that is in the best position to assure that comprehensive plans and land use regulations are consistent, fair, and applied in a manner that protects and balances the rights and interests of all Maine citizens

    Atmospheric sampling of Supertyphoon Mireille with NASA DC-8 aircraft on September 27, 1991, during PEM-West A

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    The DC‐8 mission of September 27, 1991, was designed to sample air flowing into Typhoon Mireille in the boundary layer, air in the upper tropospheric eye region, and air emerging from the typhoon and ahead of the system, also in the upper troposphere. The objective was to find how a typhoon redistributes trace constituents in the West Pacific region and whether any such redistribution is important on the global scale. The boundary layer air (300 m), in a region to the SE of the eye, contained low mixing ratios of the tracer species O3, CO, C2H6, C2H2, C3H8, C6H6 and CS2 but high values of dimethylsulfide (DMS). The eye region relative to the boundary layer, showed somewhat elevated levels of CO, substantially increased levels of O3, CS2 and all nonmethane hydrocarbons (NMHCs), and somewhat reduced levels of DMS. Ahead of the eye, CO and the NMHCs remained unchanged, O3 and CS2 showed a modest decrease, and DMS showed a substantial decrease. There was no evidence from lidar cross sections of ozone for the downward entrainment of stratospheric air into the eye region; these sections show that low ozone values were measured in the troposphere. The DMS data suggest substantial entrainment of boundary layer air into the system, particularly into the eye wall region. Estimates of the DMS sulphur flux between the boundary layer and the free troposphere, based on computations of velocity potential and divergent winds, gave values of about 69 μg S m−2 d−1 averaged over a 17.5° grid square encompassing the typhoon. A few hours after sampling with the DC‐8, Mireille passed over Oki Island, just to the north of Japan, producing surface values of ozone of 5.5 ppbv. These O3 levels are consistent with the low tropospheric values found by lidar and are more typical of equatorial regions. We suggest that the central eye region may act like a Taylor column which has moved poleward from low latitudes. The high‐altitude photochemical environment within Typhoon Mireille was found to be quite active as evidenced by significant levels of measured gas phase H2O2 and CH3OOH and model‐computed levels of OH
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