12,731 research outputs found

    Hydrogeochemistry of the Caribou-Poker Creeks Research Watershed

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    Bedrock of the Caribou-Poker Creeks Research Watershed dissolves incongruently with a first-order rate constant of about 5 x 10-6 day-1 at 5° C. The resulting solution is potassium-calcium-magnesium rich. The soil-plant environment acts on this solution through sorption of potassium and by evapotranspiration to yield a solution that is relatively depleted in potassium and enriched in calcium and magnesium, but with the same molar ratio of Ca:Mg as the fluid from the rock dissolution. This fluid from the soil-plant reservoir is the dominant contributor of ions to stream waters. Using the discriminant functions obtained by multiple discriminant analysis DPKR = 0.572Si02 + 0.240Ca + 2.89Mg - 0.384Na + 0.452N03 - 9.18 DCRB = 0.913Si02 + 0.042Ca + 1.28Mg + 1.17Na + 4.63N03 - 7.27, the waters of Caribou Creek and Poker Creek can be distinguished on the basis of chemical composition. In general, Poker Creek waters are slightly more concentrated than Caribou Creek waters. On the average, 1.4 x 10^13g H20/year leaves the watershed as surface water. At an average calcium concentration of 14 ppm for the water, 0.1% for the bedrock, and a watershed area of 46 mi^2, this flow corresponds to a maximum loss of about 17 metric tons of rock per hectare per year

    Isolated photon and photon+jet production at NNLO QCD accuracy and the ratio R13/8ÎłR_{13/8}^\gamma

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    We discuss different approaches to photon isolation in fixed-order calculations and present a new next-to-next-to-leading order (NNLO) QCD calculation of R13/8ÎłR_{13/8}^\gamma, the ratio of the inclusive isolated photon cross section at 8 TeV and 13 TeV, differential in the photon transverse momentum, which was recently measured by the ATLAS collaboration.Comment: 4 pages, 1 figure. Contribution to the 2019 QCD session of the 54th Rencontres de Morion

    Identifying the transporters of different flavonoids in plants

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    We recently identified a new component of flavonoid transport pathways in Arabidopsis. The MATE protein FFT (Flower Flavonoid Transporter) is primarily found in guard cells and seedling roots, and mutation of the transporter results in floral and growth phenotypes. The nature of FFT’s substrate requires further exploration but our data suggest that it is a kaempferol diglucoside. Here we discuss potential partner H+-ATPases and possible redundancy among the close homologues within the large Arabidopsis MATE family

    The Influence of Metallicity on Star Formation in Protogalaxies

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    In cold dark matter cosmological models, the first stars to form are believed to do so within small protogalaxies. We wish to understand how the evolution of these early protogalaxies changes once the gas forming them has been enriched with small quantities of heavy elements, which are produced and dispersed into the intergalactic medium by the first supernovae. Our initial conditions represent protogalaxies forming within a fossil H II region, a previously ionized region that has not yet had time to cool and recombine. We study the influence of low levels of metal enrichment on the cooling and collapse of ionized gas in small protogalactic halos using three-dimensional, smoothed particle hydrodynamics (SPH) simulations that incorporate the effects of the appropriate chemical and thermal processes. Our previous simulations demonstrated that for metallicities Z < 0.001 Z_sun, metal line cooling alters the density and temperature evolution of the gas by less than 1% compared to the metal-free case at densities below 1 cm-3) and temperatures above 2000 K. Here, we present the results of high-resolution simulations using particle splitting to improve resolution in regions of interest. These simulations allow us to address the question of whether there is a critical metallicity above which fine structure cooling from metals allows efficient fragmentation to occur, producing an initial mass function (IMF) resembling the local Salpeter IMF, rather than only high-mass stars.Comment: 3 pages, 2 figures, First Stars III conference proceeding

    "When we smash windows..." black blocs and breaches of the peace

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    Breach of the peace is a cornerstone of public order law in England and Wales and was considered recently by the Supreme Court in R. (on the application of Hicks) v Commissioner of Police for the Metropolis. However, the common starting-point for discussion of the doctrine is the case of Howell. It is argued here that this judgment has been misinterpreted to the extent that it requires a property owner to be present where a breach of peace is founded on harm or the threat of harm to property. The issue has been placed in stark relief by recent changes to the nature of protest. Black Bloc protestors eschew physical violence to persons but pursue a strategy of deliberate property damage. The police may intervene to prevent a breach of the peace that reasonably appears likely “in the near future”, but will be unable to intervene if the property owner is not present, unless harm to persons is anticipated or a criminal offence is “about to” be committed. This article re-examines Howell in light of the Black Bloc phenomenon and contends that, in the absence of legislation, the courts should clarify the law so that the threat of property damage is sufficient to constitute a breach of the peace whether or not the owner is present

    Novel thermal management of power electronic devices: high power high frequency planar gunn diodes

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    Thermal management of next generation of semiconductor devices is becoming more challenging, as the device power increases and device dimensions decrease. The work is addressing novel thermal measurement and management for planar heterostructure Gunn diodes, which will be of strategic importance for UK technology and industry
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