2,841 research outputs found

    Assessment of Factors Influencing Migratory Landbird Use of Forested Stopover Sites Along the Delmarva Peninsula During Autumn Migration

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    Autumn migration is a time when billions of birds move from breeding grounds in North America to wintering grounds in Central and South America, with many individuals relying on stopover habitats en route for resting and refueling purposes. These stopover sites are critical to the survival of the hundreds of species of migratory landbirds that migrate annually, and thus identifying important stopover sites is a high priority for conserving such taxa. The Delmarva Peninsula; a coastal region of Delaware, Maryland, and Virginia along the mid-Atlantic flyway; consists of forested habitats with ample food and shelter that likely serves as quality stopover sites for many species during autumn migration. Determining both extrinsic and intrinsic factors that most influence migrant use of forested stopover sites during this period is a necessary step towards providing adequate protection for vulnerable species, and one requiring a multi-scale analytical approach. I assessed the influence of variables at the regional- (i.e. proximity to the coast, location latitudinally), landscape- (i.e. proportions of surrounding land cover types), and patch-scales (i.e. habitat structure and vegetative characteristics) on migratory landbird use of forested stopover sites at 48 forested areas located across Delaware, Maryland, and Virginia during autumn migration in 2013 and 2014. Using boosted regression tree modelling techniques, I conducted analyses to determine variable influence on forested site use for 13 migratory species, as well as season-wide and early- vs. mid-season analyses using all nocturnal migratory landbird species. For season-wide analyses, autumn migration was separated into four 21-day sampling periods (period 1 = 15 Aug – 4 Sep, period 2 = 5 Sep – 15 Oct, period 3 = 26 Sep – 16 Oct, period 4 = 17 Oct – 7 Nov). Predictor variables were not consistent in influence across multiple spatial and temporal scales during the migratory season. For all season-wide analyses, including the grouped model and thirteen individual species models, time of sampling (sampling period) was the most influential predictor variable in explaining migrant density. At the regional-scale, latitude was the most consistently influential predictor variable in explaining migrant density, generally showing higher densities at sites located further north. At the landscape-scale, proportion of hardwood forest, shrubland, impervious surface, and permanent water surrounding stopover sites were all influential at predicting migrant bird density, although their degrees of influence and relationship to migrant density (positive or negative) varied greatly across models. At the patch-scale, densities of invertebrate food resources and understory vegetation were influential predictor variables across migrant models. Early in the migratory season (15 Aug – 4 Sep), proportion of surrounding land cover (low impervious surface and high shrubland and hardwood forest) and metrics associated with patch-scale habitat structure (high ground vegetation and shrub counts) were the most influential predictor variables of migrant density. Alternatively, during the middle of the migratory season (26 Sep – 16 Oct), latitude and food availability were far more influential in predicting migrant use. These results demonstrate how spatially and temporally variable migrant use of forested stopover sites can be. Using a multi-scale approach, while logistically difficult, is necessary to understand the complexity of migrant use of stopover sites

    Using NCLB to Improve Student Achievement: An Action Guide for Community and Parent Leaders

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    This guide addresses the various provisions of the No Child Left Behind Act of 2001 (called NCLB, or the act). Included are specific rights, roles, and responsibilities that offer parents and community leaders opportunities to send the no-nonsense message that unequal educational opportunities will no longer be tolerated in their public schools.The guide highlights ways NCLB can be used to strengthen the public's voice in education, and to increase community and parental involvement in school-level and district-level operations and decisions:Identifies major areas of NCLB that require or provide for community and/or parental involvement in Title I (Improving the Academic Achievement of the Disadvantaged) and Title II (Preparing, Training, and Recruiting High-Quality Teachers and Principals) of the actProvides general information on the scope and requirements for each major area of community and parental engagementBreaks down legislative language into understandable terms and recommends actions that can be taken by parents and/or the community as a result of their rights under the actProvides a formatted and easily reproduced training tool for parent/teacher meetings and town meetingsIdentifies areas in the act that are silent about community and/or parental engagement, but where PEN believes openings in the law allow parents and/or the community to exercise leadership and take initiativ

    Using mutual information to measure order in model glass-formers

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    Whether or not there is growing static order accompanying the dynamical heterogeneity and increasing relaxation times seen in glassy systems is a matter of dispute. An obstacle to resolving this issue is that the order is expected to be amorphous and so not amenable to simple order parameters. We use mutual information to provide a general measurement of order that is sensitive to multi-particle correlations. We apply this to two glass-forming systems (2D binary mixtures of hard disks with different size ratios to give varying amounts of hexatic order) and show that there is little growth of amorphous order in the system without crystalline order. In both cases we measure the dynamical length with a four-point correlation function and find that it increases significantly faster than the static lengths in the system as density is increased. We further show that we can recover the known scaling of the dynamic correlation length in a kinetically constrained model, the 2-TLG.Comment: 10 pages, 12 Figure

    Mid-frequency aperture arrays: the future of radio astronomy

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    Aperture array (AA) technology is at the forefront of new developments and discoveries in radio astronomy. Currently LOFAR is successfully demonstrating the capabilities of dense and sparse AA's at low frequencies. For the mid-frequencies, from 450 to 1450MHz, AA's still have to prove their scientific value with respect to the existing dish technology. Their large field-of-view and high flexibility puts them in an excellent position to do so. The Aperture Array Verification Program is dedicated to demonstrate the feasibility of AA's for science in general and SKA in particular. For the mid-frequency range this has lead to the development of EMBRACE, which has already demonstrated the enormous flexibility of AA systems by observing HI and a pulsar simultaneously. It also serves as a testbed to demonstrate the technological reliability and stability of AA's. The next step will put AA technology at a level where it can be used for cutting-edge science. In this paper we discuss the developments to move AA technology from an engineering activity to a fully science capable instrument. We present current results from EMBRACE, ongoing tests of the system, and plans for EMMA, the next step in mid-frequency AA technology.Comment: 8 pages, 7 figures, proceedings of Resolving The Sky - Radio Astronomy: Past, Present and Future (RTS2012), April 17-20, 2012, Manchester, U

    Absolute Timing of the Crab Pulsar with RXTE

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    We have monitored the phase of the main X-ray pulse of the Crab pulsar with the Rossi X-ray Timing Explorer (RXTE) for almost eight years, since the start of the mission in January 1996. The absolute time of RXTE's clock is sufficiently accurate to allow this phase to be compared directly with the radio profile. Our monitoring observations of the pulsar took place bi-weekly (during the periods when it was at least 30 degrees from the Sun) and we correlated the data with radio timing ephemerides derived from observations made at Jodrell Bank. We have determined the phase of the X-ray main pulse for each observation with a typical error in the individual data points of 50 us. The total ensemble is consistent with a phase that is constant over the monitoring period, with the X-ray pulse leading the radio pulse by 0.0102+/-0.0012 period in phase, or 344+/-40 us in time. The error estimate is dominated by a systematic error of 40 us in the radio data, arising from uncertainties in the variable amount of pulse delay due to interstellar scattering and instrumental calibration. The statistical error is 0.00015 period, or 5 us. The separation of the main pulse and interpulse appears to be unchanging at time scales of a year or less, with an average value of 0.4001+/-0.0002 period. There is no apparent variation in these values with energy over the 2-30 keV range. The lag between the radio and X-ray pulses may be constant in phase (rotational) or constant in time (linear pathlength). We are not (yet) able to distinguish between these two interpretations.Comment: 11 pages, 2 figure

    A transmission model for Salmonella in grower-finisher pigs

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    This paper presents a model describing the dynamic transmission of Salmonella Typhimurium between pigs on a typical, British pig grower-finisher farm. A modified Reed-Frost discrete-time model was used to estimate the probability of infection for susceptible pigs

    The role of comparisons in judgments of loneliness

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    Loneliness—perceived social isolation—is defined as a discrepancy between existing social relationships and desired quality of relationships. Whereas most research has focused on existing relationships, we consider the standards against which people compare them. Participants who made downward social or temporal comparisons that depicted their contact with others as better (compared to other people’s contact or compared to the past) reported less loneliness than participants who made upward comparisons that depicted their contact with others as worse (Study 1–3). Extending these causal results, in a survey of British adults, upward social comparisons predicted current loneliness, even when controlling for loneliness at a previous point in time (Study 4). Finally, content analyses of interviews with American adults who lived alone showed that social and temporal comparisons about contact with others were both prevalent and linked to expressed loneliness (Study 5). These findings contribute to understanding the social cognition of loneliness, extend the effects of comparisons about social connection to the important public health problem of loneliness, and provide a novel tool for acutely manipulating loneliness

    Impacts of Changes to County Educator Position Descriptions on Gender and Educational Diversity

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    For the purposes of more accurately reflecting job duties and increasing diversity, Ohio county agriculture and natural resources educator position descriptions were changed in 2013 to include natural resources as an educational qualification. We examined applicant and hiring data from 3 years before and 3 years after the position description change. Results indicate that the numbers of women applicants and applicants with natural resources degrees increased following the position description change. However, although the percentage of hires with natural resources backgrounds increased, the percentage of female hires decreased sharply. Factors influencing the hiring of county agriculture and natural resources educators need to be examined
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