1,968 research outputs found

    UTM, a universal simulator for lightcurves of transiting systems

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    The Universal Transit Modeller (UTM) is a light-curve simulator for all kinds of transiting or eclipsing configurations between arbitrary numbers of several types of objects, which may be stars, planets, planetary moons, and planetary rings. Applications of UTM to date have been mainly in the generation of light-curves for the testing of detection algorithms. For the preparation of such test for the Corot Mission, a special version has been used to generate multicolour light-curves in Corot's passbands. A separate fitting program, UFIT (Universal Fitter) is part of the UTM distribution and may be used to derive best fits to light-curves for any set of continuously variable parameters. UTM/UFIT is written in IDL code and its source is released in the public domain under the GNU General Public License.Comment: 4 pages, 2 figures, to appear in Proc. of'Transiting Planets', IAU Symposium 25

    CoRoT pictures transiting exoplanets

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    The detection and characterization of exoplanets have made huge progresses since the first discoveries in the late nineties. In particular, the independent measurement of the mass and radius of planets, by combining the transit and radial-velociy techniques, allowed exploring their density and hence, their internal structure. With CoRoT (2007-2012), the pioneering CNES space-based mission in this investigation, about thirty new planets were characterized. CoRoT has enhanced the diversity of giant exoplanets and discovered the first telluric exoplanet. Following CoRoT, the NASA Kepler mission has extended our knowledge to small-size planets, multiple systems and planets orbiting binaries. Exploring these new worlds will continue with the NASA/TESS (2017) and ESA/PLATO (2024) missions.Comment: in Comptes Rendus de l'Academie des Sciences / Geoscienc

    TRENDS IN U.S. WHEAT-BASED FOOD CONSUMPTION: NUTRITION, CONVENIENCE, AND ETHNIC FOODS

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    This study identifies U.S. consumers' use of food nutrition labels on wheat-based foods; consumer attitudes toward the importance of taste, price, and nutrition in choosing wheat-based snack foods; and consumer knowledge of Middle-Eastern wheat-based foods. A survey of U.S. primary grocery shoppers indicated that most respondents believed it was important that their diets contained wheat-based food products. A majority of respondents indicated that fat content was the most important item on food nutrition labels when making a wheat-based food purchase decision. A majority of respondents indicated that taste was the most important factor when making wheat-based snack food purchases. Most respondents were not familiar with Middle-Eastern wheat-based foods.Food Consumption/Nutrition/Food Safety,

    Snapshot coronagraphy with an interferometer in space

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    Diluted arrays of many optical apertures will be able to provide h igh-resolution snapshot images if the beams are combined according to the densified-pupil scheme. We show that the same principle can also provide coronagraphic images, for detecting faint sources near a bright unresolved one. Recent refinements of coronagraphic techniques, i.e. the use of a phase mask, active apodization and dark-speckle analysis, are also applicable for enhanced contrast. Implemented in the form of a proposed 50-500m Exo-Earth Discoverer array in space, the principle can serve to detect Earth-like exo-planets in the infra-red. It can also provide images of faint nebulosity near stars, active galactic nuclei and quasars. Calculations indicate that exo-planets are detectable amidst the zodiacal and exo-zodiacal emission faster than with a Bracewell array of equivalent area, a consequence of the spatial selectivity in the image.Comment: 23 pages, 10 figures, to appear in Icaru

    C60_{60} in Reflection Nebulae

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    The fullerene C60_{60} has four infrared-active vibrational transitions at 7.0, 8.5, 17.4 and 18.9 μ\mum. We have previously observed emission features at 17.4 and 18.9 μ\mum in the reflection nebula NGC 7023 and demonstrated spatial correlations suggestive of a common origin. We now confirm our earlier identification of these features with C60_{60} by detecting a third emission feature at 7.04 ±\pm 0.05 μ\mum in NGC 7023. We also report the detection of these three C60_{60} features in the reflection nebula NGC 2023. Our spectroscopic mapping of NGC 7023 shows that the 18.9 μ\mum C60_{60} feature peaks on the central star and that the 16.4 μ\mum emission feature due to polycyclic aromatic hydrocarbons peaks between the star and a nearby photodissociation front. The observed features in NGC 7023 are consistent with emission from UV-excited gas-phase C60_{60}. We find that 0.1-0.6% of interstellar carbon is in C60_{60}; this abundance is consistent with those from previous upper limits and possible fullerene detections in the interstellar medium. This is the first firm detection of neutral C60_{60} in the interstellar medium.Comment: ApJ Letters, in pres

    Car Parking Matters to Small Retailers: An Historical Case Study of Three Town Centres in Marrickville

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    Increasing the costs of car parking and in some cases removing it has become recommended practice for discouraging car use. To understand the perspective of the high street retail cluster who will be confronted with such changes, the paper reviews a time when another change in mobility and access led to car parking construction. A case study of local newspaper coverage between 1968-87 about car parks in the Marrickville Council area is analysed for themes, using a sociological framework of mobility. The paper concludes that while policies of the past may have prioritised economic needs the paradigm shift of sustainable decision making means that future policy implementation will be more complex. In town centres this requires more attention to be paid to the needs of those not engaged in the policy debate, but who are dependent upon the existing infrastructure of car parking. Small retail businesses are one such group.The symposium is organised on behalf of AAHANZBS by the Business and Labour History Group, The University of Sydney, with the financial support of the University’s Faculty of Economics and Business

    Approaching the limits

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    Front- vs. back-illuminated CCD cameras for photometric surveys: a noise budget analysis

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    Exoplanetary transit and stellar oscillation surveys require a very high precision photometry. The instrumental noise has therefore to be minimized. First, we perform a semi-analytical model of different noise sources. We show that the noise due the CCD electrodes can be overcome using a Gaussian PSF (Point Spread Function) of full width half maximum larger than 1.6 pixels. We also find that for a PSF size of a few pixels, the photometric aperture has to be at least 2.5 times larger than the PSF full width half maximum. Then, we compare a front- with a back-illuminated CCD through a Monte-Carlo simulation. Both cameras give the same results for a PSF full width half maximum larger than 1.5 pixels. All these simulations are applied to the A STEP (Antarctica Search for Transiting Extrasolar Planets) project. As a result, we choose a front-illuminated camera for A STEP because of its better resolution and lower price, and we will use a PSF larger than 1.6 pixels
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