27,731 research outputs found

    Still the century of ‘new’ environmental policy instruments? Exploring patterns of innovation and continuity

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    This article re-examines the political interest in and use of ‘new' environmental policy instruments (NEPIs) and other non-regulatory modes of governance. It starts by taking stock of the dynamic debate that has emerged around this topic since the turn of the century. It then contextualizes that debate by examining subsequent challenges to, and transformations in state-led governing and the widely acknowledged rise of 'new governance' more generally. It highlights the mismatch between: (a) the animated discussion of new instruments amongst policy makers and academics; and (b), the less active adoption and performance of them in practice. It makes an overall assessment of the role of instruments - both ‘old' and ‘new' - in the wider debate about governance, and suggests some steps that could be taken by both practitioners and scholars better to understand and possibly even utilise more NEPIs in the future

    Universal thermodynamic bounds on nonequilibrium response with biochemical applications

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    Diverse physical systems are characterized by their response to small perturbations. Near thermodynamic equilibrium, the fluctuation-dissipation theorem provides a powerful theoretical and experimental tool to determine the nature of response by observing spontaneous equilibrium fluctuations. In this spirit, we derive here a collection of equalities and inequalities valid arbitrarily far from equilibrium that constrain the response of nonequilibrium steady states in terms of the strength of nonequilibrium driving. Our work opens new avenues for characterizing nonequilibrium response. As illustrations, we show how our results rationalize the energetic requirements of two common biochemical motifs.Comment: 21 pages, 15 figure

    Synthesis of calculational methods for design and analysis of radiation shields for nuclear rocket systems

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    Eight computer programs make up a nine volume synthesis containing two design methods for nuclear rocket radiation shields. The first design method is appropriate for parametric and preliminary studies, while the second accomplishes the verification of a final nuclear rocket reactor design

    Phase-resolved far-ultraviolet HST spectroscopy of the peculiar magnetic white dwarf RE J0317-853

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    We present phase resolved FUV HST FOS spectra of the rapidly rotating, highly magnetic white dwarf RE J0317-853. Using these data, we construct a new model for the magnetic field morphology across the stellar surface. From an expansion into spherical harmonics, we find the range of magnetic field strengths present is 180-800MG. For the first time we could identify an absorption feature present at certain phases at 1160A as a ``forbidden'' 1s_0 -> 2s_0 component, due to the combined presence of an electric and magnetic field.Comment: 15 pages including 4 figures. Accepted for publication in ApJ Letter

    Model for Cumulative Solar Heavy Ion Energy and Linear Energy Transfer Spectra

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    A probabilistic model of cumulative solar heavy ion energy and LET spectra is developed for spacecraft design applications. Spectra are given as a function of confidence level, mission time period during solar maximum and shielding thickness. It is shown that long-term solar heavy ion fluxes exceed galactic cosmic ray fluxes during solar maximum for shielding levels of interest. Cumulative solar heavy ion fluences should therefore be accounted for in single event effects rate calculations and in the planning of space missions

    Fluorescence Near-Field Microscopy of DNA at Sub-10 nm Resolution

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    We demonstrate apertureless near-field microscopy of single molecules at sub-10 nm resolution. With a novel phase filter, near-field images of single organic fluorophores were obtained with ~sixfold improvement in the signal-to-noise ratio. The improvement allowed pairs of molecules separated by ~15 nm to be reliably and repeatedly resolved, thus demonstrating the first true Rayleigh resolution test for near-field images of single molecules. The potential of this technique for biological applications was demonstrated with an experiment that measured the helical rise of A-form DNA

    Tip-Enhanced Fluorescence Microscopy at 10 Nanometer Resolution

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    We demonstrate unambiguously that the field enhancement near the apex of a laser-illuminated silicon tip decays according to a power law that is moderated by a single parameter characterizing the tip sharpness. Oscillating the probe in intermittent contact with a semiconductor nanocrystal strongly modulates the fluorescence excitation rate, providing robust optical contrast and enabling excellent background rejection. Laterally encoded demodulation yields images with <10 nm spatial resolution, consistent with independent measurements of tip sharpness

    A periodically active pulsar giving insight into magnetospheric physics

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    PSR B1931+24 (J1933+2421) behaves as an ordinary isolated radio pulsar during active phases that are 5-10 days long. However, the radio emission switches off in less than 10 seconds and remains undetectable for the next 25-35 days, then it switches on again. This pattern repeats quasi-periodically. The origin of this behaviour is unclear. Even more remarkably, the pulsar rotation slows down 50% faster when it is on than when it is off. This indicates a massive increase in magnetospheric currents when the pulsar switches on, proving that pulsar wind plays a substantial role in pulsar spin-down. This allows us, for the first time, to estimate the currents in a pulsar magnetospheric during the occurrence of radio emission.Comment: 12 pages, 2 figure
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