7,641 research outputs found

    Ten Bee Species New to Green Roofs in the Chicago Area

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    Green roofs increasingly provide habitat for many insects in urban environments. Pollinators such as bees may utilize foraging and nesting resources provided by green roofs but few studies have documented which species occur in these novel habitats. This study identified bees from 26 species, 11 genera and 5 families collected from 7 green roofs using pan trapping methods over 2 years. Ten of these species have not previously been recorded on green roofs in the Chicago region. Although the majority of bee species collected were solitary, soil-nesting, and native to Illinois, the proportion of exotic species was high compared to previous collections from Chicago area green roofs and urban parks. Urban green roofs may enhance populations of both native and exotic bees, but their ability to support the same range of native diversity recorded from other urban habitats requires further investigation

    Testing the Effectiveness of Regulation and Competition on Cable Television Rates

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    Regulation of the cable television industry was marked by remarkable periods of deregulation, re-regulation, and re-deregulation during the 1980s and 1990s. Using FCC firm-level survey data spanning 1993 to 2001, we model and econometrically estimate the effect of regulation and competition on cable rates. Our calculations indicate that while regulation lowered rates for small system operators, it raised them for medium and large systems. Meanwhile, competition consistently decreased rates from 5.6 to 8.8 percent, with even larger declines during periods of regulation. Our results suggest that competition is more effective than regulation in containing cable prices.cable rates, regulation, competition

    Testing the Effectiveness of Regulation and Competition on Cable Television Rates

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    Regulation of the cable television industry was marked by remarkable periods of deregulation, re-regulation, and re-deregulation during the 1980s and 1990s. Using FCC firm-level survey data spanning 1993 to 2001, we model and econometrically estimate the effect of regulation and competition on cable rates. Our calculations indicate that while regulation lowered rates for small system operators, it raised them for medium and large systems. Meanwhile, competition consistently decreased rates from 5.6 to 8.8 percent, with even larger declines during periods of regulation. Our results suggest that competition is more effective than regulation in containing cable prices.cable rates, regulation, competition

    The experiences of women with polycystic ovary syndrome on a very low-calorie diet

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    The research was funded by an educational grant from LighterLife. Broom was the Medical Director for LighterLife at the time of the research. Johnson is the Head of Nutrition and Research at LighterLife. The authors report no other conflicts of interest in this work.Peer reviewedPublisher PD

    Observing mergers of non-spinning black-hole binaries

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    Advances in the field of numerical relativity now make it possible to calculate the final, most powerful merger phase of binary black-hole coalescence for generic binaries. The state of the art has advanced well beyond the equal-mass case into the unequal-mass and spinning regions of parameter space. We present a study of the nonspinning portion of parameter space, primarily using an analytic waveform model tuned to available numerical data, with an emphasis on observational implications. We investigate the impact of varied mass ratio on merger signal-to-noise ratios (SNRs) for several detectors, and compare our results with expectations from the test-mass limit. We note a striking similarity of the waveform phasing of the merger waveform across the available mass ratios. Motivated by this, we calculate the match between our 1:1 (equal mass) and 4:1 mass-ratio waveforms during the merger as a function of location on the source sky, using a new formalism for the match that accounts for higher harmonics. This is an indicator of the amount of degeneracy in mass ratio for mergers of moderate-mass-ratio systems.Comment: 13 pages, 11 figures, submitted to Phys. Rev.

    A colimit decomposition for homotopy algebras in Cat

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    Badzioch showed that in the category of simplicial sets each homotopy algebra of a Lawvere theory is weakly equivalent to a strict algebra. In seeking to extend this result to other contexts Rosicky observed a key point to be that each homotopy colimit in simplicial sets admits a decomposition into a homotopy sifted colimit of finite coproducts, and asked the author whether a similar decomposition holds in the 2-category of categories Cat. Our purpose in the present paper is to show that this is the case.Comment: Some notation changed; small amount of exposition added in intr

    Computational modelling of the design conversation as a sequence of situated acts

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    This paper describes the design conversation as a sequence of situated acts. It distinguishes the research questions that require attention for the computation of a more situated design conversation; in terms of design actions and design interpretations. It presents an architecture for 'more situated' systems and describes some examples of implementation. The limitations and complexities of what has been achieved are identified

    Development and testing of three dimensional, two-fluid code THERMIT for LWR core and subchannel applications

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    At head of title: Energy Laboratory and Dept. of Nuclear Engineering.Sponsored by Boston Edison Company and others under MIT Energy Laboratory Electric Utility Program

    Defining the Costs of an Outbreak of Karnal Bunt of Wheat

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    In determining the economic impact of a possible outbreak of the quarantinable wheat disease Karnal Bunt, an examination was made of the detailed components of the costs involved. The costs were classified as: (a) Direct costs (yield and quality losses); (b) Reaction costs (export bans, quality down-grading, seed industry costs); and (c) Control costs (quarantine zones, fungicides, spore destruction). The relative importance of each of these cost components is measured for a hypothetical outbreak of Karnal Bunt in the European Union, as a means of ensuring that the policy responses to such an outbreak are appropriate considering the costs involved.disease, quarantine, cost, wheat, Agricultural and Food Policy, Crop Production/Industries,

    Corolla Morphology Facilitates Both Autogamy and Bumblebee Pollination in Mimulus guttatus

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    The showy corolla of Mimulus guttatus is generally considered an adaptation to attract pollinators. We use phenotypic manipulations to demonstrate that corolla morphology plays a critical mechanical role in both outcrossing and self‐fertilization. In the absence of pollinators, the lower portion of the corolla facilitates autogamy by retaining pollen released from the anthers. A substantial portion of self‐fertilization seems to occur late in the floral life span as the stigma contacts the corolla. When pollinators are present, the corolla facilitates outcrossing before, during, and after insect visitation. A large fraction of cross‐pollen is actually captured by the corolla and not by the stigma. This “indirect” pathway for pollen reception suggests that a large fraction of cross‐pollination in M. guttatus actually occurs long after a pollinator departs from a flower
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