10,011 research outputs found

    The Gaia Ultra-Cool Dwarf Sample -- II : Structure at the end of the main sequence

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    © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.We identify and investigate known late M, L, and T dwarfs in the Gaia second data release. This sample is being used as a training set in the Gaia data processing chain of the ultracool dwarfs work package. We find 695 objects in the optical spectral range M8–T6 with accurate Gaia coordinates, proper motions, and parallaxes which we combine with published spectral types and photometry from large area optical and infrared sky surveys. We find that 100 objects are in 47 multiple systems, of which 27 systems are published and 20 are new. These will be useful benchmark systems and we discuss the requirements to produce a complete catalogue of multiple systems with an ultracool dwarf component. We examine the magnitudes in the Gaia passbands and find that the G BP magnitudes are unreliable and should not be used for these objects. We examine progressively redder colour–magnitude diagrams and see a notable increase in the main-sequence scatter and a bivariate main sequence for old and young objects. We provide an absolute magnitude – spectral subtype calibration for G and G RP passbands along with linear fits over the range M8–L8 for other passbands.Peer reviewedFinal Published versio

    Induction of Plant Defense Gene Expression by Plant Activators and Pseudomonas syringae pv. tomato in Greenhouse-Grown Tomatoes

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    Plant activators provide an appealing management option for bacterial diseases of greenhouse-grown tomatoes. Two types of plant activators, one that induces systemic acquired resistance (SAR) and a second that activates induced systemic resistance (ISR), were evaluated for control of Pseudomonas syringae pv. tomato and effect on plant defense gene activation. Benzothiadiazole (BTH, SAR-inducing compound) effectively reduced bacterial speck incidence and severity, both alone and in combination with the ISR-inducing product. Application of BTH also led to elevated activation of salicylic acid and ethylene-mediated responses, based on real-time polymerase chain reaction analysis of marker gene expression levels. In contrast, the ISR-inducing product (made up of plant growth-promoting rhizobacteria) inconsistently modified defense gene expression and did not provide disease control to the same level as did BTH. No antagonism was observed by combining the two activators as control of bacterial speck was similar to or better than BTH alone

    Low-Temperature Supercapacitors

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    An effort to extend the low-temperature operational limit of supercapacitors is currently underway. At present, commercially available non-aqueous supercapacitors are rated for a minimum operating temperature of -40 C. A capability to operate at lower temperatures would be desirable for delivering power to systems that must operate in outer space or in the Polar Regions on Earth. Supercapacitors (also known as double-layer or electrochemical capacitors) offer a high power density (>1,000 W/kg) and moderate energy density (about 5 to 10 Wh/kg) technology for storing energy and delivering power. This combination of properties enables delivery of large currents for pulsed applications, or alternatively, smaller currents for low duty cycle applications. The mechanism of storage of electric charge in a supercapacitor -- at the electrical double-layer formed at a solid-electrode/liquid-electrolyte interface -- differs from that of a primary or secondary electrochemical cell (i.e., a battery) in such a manner as to impart a long cycle life (typically >10(exp 6) charge/discharge cycles)

    Canopy microclimate modification for the cultivar Shiraz I. Definition of canopy microclimate

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    Three treatments providing different canopy microclimates were applied to mature Shiraz grapevines at Gawler River 30 d before veraison. Constraining foliage into a smaller volume increased shading over control vines, and GDC training and slashing reduced it. Measurements demonstrated significant differences in terms of fruit exposure to solar radiation. Effects on microclimate due to vine vigour were also noted. A K balance made on vine shoots demonstrated that shade was associated with increased K concentrations in the leaves, petioles and stems at veraison. A visual scoring system of microclimate and growth characteristics was evaluated, and results correlated weil with microclimate measurements. A conceptual model is proposed to: explairi how soil and climatic factors and cultural decision can affect canopy microclimate

    Low Temperature Double-Layer Capacitors Using Asymmetric and Spiro-Type Quaternary Ammonium Salts

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    Double-layer capacitors capable of operating at extremely low temperatures (e.g., as low as -80.degree. C.) are disclosed. Electrolyte solutions combining a base solvent (e.g., acetonitrile) and a cosolvent are employed to lower the melting point of the base electrolyte. Example cosolvents include methyl formate, ethyl acetate, methyl acetate, propionitrile, butyronitrile, and 1,3-dioxolane. A quaternary ammonium salt including at least one of triethylmethylammonium tetrafluoroborate (TEMATFB) and spiro-(1,1')-bipyrrolidium tetrafluoroborate (SBPBF.sub.4), is used in an optimized concentration (e.g., 0.10 M to 0.75 M), dissolved into the electrolyte solution. Conventional device form factors and structural elements (e.g., porous carbon electrodes and a polyethylene separator) may be employed

    Canopy microclimate modification for the cultivar Shiraz II. Effects on must and wine composition

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    The degree of shade in Shiraz grapevine canopies was varied by four treatments and a naturally occurring vigour gradient. A shaded canopy microclimate produced must compositions of reduced sugar content and higher malic acid and K concentrations, and pH. Wines from these musts also showed higher pH, K and reduced proportions of ionised anthocyanins. Correlation studies showed that high must and wine pH and K content were positively correlated with shading in the canopy, and that colour density, total and ionised anthocyanins and phenol concentrations were negatively correlated with shading.An eight-character visual scorecard of grapevine canopies was used to describe the canopies, and the results correlated with must sugar, pH and K, and wine pH, acidity, K, colour density, total and ionised anthocyanins and phenol content. Vines of high vigour produced similar must and wine composition as shaded canopy treatments

    The effects of light pruning, irrigation and improved soil management on wine quality of the Vitis vinifera cv. Riesling

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    A number of yield improving viticultural practices were assessed in terms of their effect on wine quality. These were improved soil management, lighter pruning/higher trellis, irrigation and a control. In the first year a yield increase of 1.6 t /ha for the irrigation treatment had no significant effect on wine quality. A procedure is presented to assess judges for reliability, discrimination, variability and stability as part of analysis of the sensory results. Four judges were able to consistently identify lot differences
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