16,723 research outputs found

    Marking Adult Colorado Potato Beetles, \u3ci\u3eLeptinotarsa Decemlineata\u3c/i\u3e (Coleoptera: Chrysomelidae) Using Paper Labels

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    The smooth elytra of adult Colorado potato beetle, Leptinotarsa decemlineata, make this insect difficult to make efficiently for long-term field studies. Enamel paint marks fell off rapidly, and after 28 days, 25010 of marked beetles had lost all four original marks. Use of small paper labels glued to the elytra after an acetone wash and sanding pretreatment was the most effective method for long term marking of individual beetles. Mortality in labeled laboratory-reared and field-collected beetles did not increase when compared to unmarked beetles

    Spontaneous dressed-state polarization in the strong driving regime of cavity QED

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    We utilize high-bandwidth phase quadrature homodyne measurement of the light transmitted through a Fabry-Perot cavity, driven strongly and on resonance, to detect excess phase noise induced by a single intracavity atom. We analyze the correlation properties and driving-strength dependence of the atom-induced phase noise to establish that it corresponds to the long-predicted phenomenon of spontaneous dressed-state polarization. Our experiment thus provides a demonstration of cavity quantum electrodynamics in the strong driving regime, in which one atom interacts strongly with a many-photon cavity field to produce novel quantum stochastic behavior.Comment: 4 pages, 4 color figure

    VALUING WATER QUALITY MONITORING: A CONTINGENT VALUATION EXPERIMENT INVOLVING HYPOTHETICAL AND REAL PAYMENTS

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    This paper studies the preferences and willingness-to-pay for individuals for volunteer water quality monitoring programs. The study involves supporting water quality monitoring at two ponds in the state of Rhode Island. The paper uses both a hypothetical and a real-payment contingent valuation survey to directly measure individual preferences and willingness-to-pay (WTP) for volunteer water quality monitoring at the two ponds. The overall results of the study suggest that hypothetical WTP is not statistically greater than real WTP, and that the average survey respondent is willing to support water quality monitoring on one of the two ponds. The study also finds that the specified purpose of water quality monitoring and certain socioeconomic characteristics of a respondent significantly affect the respondent's decision to support volunteer water quality monitoring.Environmental Economics and Policy,

    Four-wave mixing wavelength conversion efficiency in semiconductor traveling-wave amplifiers measured to 65 nm of wavelength shift

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    The efficiency of broadband optical wavelength conversion by four-wave mixing in semiconductor traveling-wave amplifiers is measured for wavelength shifts up to 65 nm using a tandem amplifier geometry. A quantity we call the relative conversion efficiency function, which determines the strength of the four-wave mixing nonlinearity, was extracted from the data. Using this quantity, gain requirements for lossless four-wave mixing wavelength conversion are calculated and discussed. Signal to background noise ratio is also measured and discussed in this study

    Four-Wave Mixing in Semiconductor Traveling-wave Amplifiers for Efficient, Broadband, Wavelength Conversion up to 65 nm

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    Wavelength conversion is recognized as an important function in future fiber networks employing wavelength division multiplexing. The authors have recently demonstrated broad-band wavelength conversion over spans as large as 27 nm. Their approach uses ultra-fast four-wave mixing dynamics associated with intraband relaxation mechanisms in semiconductor traveling-wave amplifiers (TWA's). In the paper the authors present new results showing conversion over wavelength spans as large as 65 nm. This surpasses the previous record by over a factor of two. Of equal importance, they also verify experimentally their previous theoretical prediction that wavelength conversion efficiency varies as the cube of TWA single pass gain. In the course of our previous work, we have shown that the theoretical efficiency, η, of this process can be expressed by the simple relation: η = 3G + 2P + R(Δ⋋) where η is the ratio in dB of the converted signal output power to the signal input power and G is the single pass TWA optical gain. A crucial point is the presence of 3G in this expression - essentially, the wavelength converter uses the available TWA optimal gain three times. We verified this expression using an experimental setup similar to that described in. Tunable, single-frequency, erbium fiber ring lasers were used as pump and signal sources and TWA devices used contained tensile-strained mutli-quantum well active layers described in. Figure 1 shows conversion efficiency data plotted versus single-pass saturated optical gain. The pump power was -5.2 dBm and the signal power was -11.3 dBm. The measured slope of 3.18 confirms the cubic dependence of efficiency on single pass gain

    Study of interwell carrier transport by terahertz four-wave mixing in an optical amplifier with tensile and compressively strained quantum wells

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    Interwell carrier transport in a semiconductor optical amplifier having a structure of alternating tensile and compressively strained quantum wells was studied by four-wave mixing at detuning frequencies up to 1 THz. A calculation of transbarrier transport efficiency is also presented to qualitatively explain the measured signal spectra

    Memoir on Hugh Miller (1802–1856) by his son Hugh Miller (1850–1896) in "Calotypes by D. O. Hill and R. Adamson: illustrating an early stage in the development of photography. Selected from his collection by Andrew Elliot", 1928. Transcribed and annotated by Michael A. Taylor 2017.

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    Memoir on Hugh Miller (1802–1856) by his son Hugh Miller (1850–1896) in "Calotypes by D. O. Hill and R. Adamson: illustrating an early stage in the development of photography. Selected from his collection by Andrew Elliot". Printed for private circulation, Edinburgh, 1928. (pages 13-18). Transcribed and annotated by Michael. A. Taylor, with the kind permission of Henry McKenzie Johnston CB on behalf of the Miller family; and with the kind assistance of Becky Howell and colleagues (Scottish National Portrait Gallery) and technical assistance from Richard C. Harley. Transcript is verbatim except for converting the asterisks, etc., used to indicate the original footnotes into numbers. Modern comments [in square brackets] have also been added, especially to indicate original pagination and identify some references and allusions

    Autonomic physiological data associated with simulator discomfort

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    The development of a physiological monitoring capability for the Army's advanced helicopter simulator facility is reported. Additionally, preliminary physiological data is presented. Our objective was to demonstrate the sensitivity of physiological measures in this simulator to self-reported simulator sickness. The data suggested that heart period, hypergastria, and skin conductance level were more sensitive to simulator sickness than were vagal tone and normal electrogastric activity
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