1,951 research outputs found

    Orientation-dependent binding energy of graphene on palladium

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    Using density functional theory calculations, we show that the binding strength of a graphene monolayer on Pd(111) can vary between physisorption and chemisorption depending on its orientation. By studying the interfacial charge transfer, we have identified a specific four-atom carbon cluster that is responsible for the local bonding of graphene to Pd(111). The areal density of such clusters varies with the in-plane orientation of graphene, causing the binding energy to change accordingly. Similar investigations can also apply to other metal substrates, and suggests that physical, chemical, and mechanical properties of graphene may be controlled by changing its orientation.Comment: 5 pages, 6 figure

    Exchange and correlation energies of ground states of atoms and molecules in strong magnetic fields

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    Using a Hartree-Fock mesh method and a configuration interaction approach based on a generalized Gaussian basis set we investigate the behaviour of the exchange and correlation energies of small atoms and molecules, namely th e helium and lithium atom as well as the hydrogen molecule, in the presence of a magnetic field covering the regime B=0-100a.u. In general the importance of the exchange energy to the binding properties of at oms or molecules increases strongly with increasing field strength. This is due to the spin-flip transitions and in particular due to the contributions of the tightly bound hydrogenic state s which are involved in the corresponding ground states of different symmetries. In contrast to the exchange energy the correlation energy becomes less relevant with increasing field strength. This holds for the individual configurations constituting the ground state and for the crossovers of the global ground state.Comment: 4 Figures acc.f.publ.in Phys.Rev.

    Reconstruction methods for acoustic particle detection in the deep sea using clusters of hydrophones

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    This article focuses on techniques for acoustic noise reduction, signal filters and source reconstruction. For noise reduction, bandpass filters and cross correlations are found to be efficient and fast ways to improve the signal to noise ratio and identify a possible neutrino-induced acoustic signal. The reconstruction of the position of an acoustic point source in the sea is performed by using small-volume clusters of hydrophones (about 1 cubic meter) for direction reconstruction by a beamforming algorithm. The directional information from a number of such clusters allows for position reconstruction. The algorithms for data filtering, direction and position reconstruction are explained and demonstrated using simulated data.Comment: 7 pages, 13 figure

    Feeding Practices in South Dakota Cattle Feedlots

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    During March 1989, a mail survey of South Dakota cattle feedlot managers was undertaken. The purposes of the survey were to characterize the nature of the cattle feeding industry in South Dakota and to determine the relationships between (i) each of size-of-feedlot and geographic location within the state and (ii) management practices followed by cattle feeders. Direct relationships exist between size-of-feedlot and the following: (1) rate of feedlot utilization in each quarter of the year (P\u3c.10); (2) percentage grain relative to roughage in both growing and finishing diets (P\u3c.10); (3) percentage of feedlots feeding high moisture grain, cracked grain, and ground hay (P\u3c.01); (4) percentage of feedlots using rumen stimulants and growth implants (P\u3c.01); and (5) percentages of managers testing feeds for nutrient composition, using feed scales to control feeding rates, maintaining feed records for separate pens of cattle, and hiring consultants to formulate rations (P\u3c.01). On the other hand, inverse relationships exist between size-of-feedlot and the following: (6) days on feed for heifer calves, yearling steers, and yearling heifers (P\u3c.10); (7) slaughter weight of steers (Pc.10); (8) percentage of home-raised hay and dry grain (P\u3c.10); (9) percentage of feedlots feeding ground grain and unprocessed hay (P\u3c.01); and (10) percentage of feedlots not using feed additives (P\u3c.10). Average days on feed for steer and heifer calves are lower (P\u3c.05) in the West than in other areas of the state. More milo is fed in the West; more barley is fed in the North Central region; and less home-raised corn silage and haylage are fed in the West than in other regions (P\u3c.05)

    KM3NeT:a large underwater neutrino telescope in the Mediterranean Sea

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    High energy neutrinos produced in astrophysical processes will allow for a new way of studying the universe. In order to detect the expected flux of high energy neutrinos from specific astrophysical sources, neutrino telescopes of a scale of a km^3 of water will be needed. A Northern Hemisphere detector is being proposed to be sited in a deep area of the Mediterranean Sea. This detector will provide complimentary sky coverage to the IceCube detector being built at the South Pole. The three neutrino telescope projects in the Mediterranean (ANTARES, NEMO and NESTOR) are partners in an effort to design, and build such a km^3 size neutrino telescope, the KM3NeT. The EU is funding a 3-year Design Study; the status of the Design Study is presented and some technical issues are discussed.Comment: 4 pages, 3 figures, Prepared for the 10th International Conference on Astroparticle and Underground Physics (TAUP 2007), Sendai, Japan, 11-15 Sep 200

    Measurements and Simulation Studies of Piezoceramics for Acoustic Particle Detection

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    Calibration sources are an indispensable tool for all detectors. In acoustic particle detection the goal of a calibration source is to mimic neutrino signatures as expected from hadronic cascades. A simple and promising method for the emulation of neutrino signals are piezo ceramics. We will present results of measruements and simulations on these piezo ceramics.Comment: 5 pages, 5 figure

    Feijão comum: características morfo-agronômicas de cultivares.

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    O presente trabalho objetivou avaliar as características morfoagronômicas de cultivares de feijão comum de diversos grupos comerciais na época de safrinha

    Componentes produtivos de cultivares de feijão comum em cultivo safrinha.

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    O presente trabalho teve por objetivo avaliar os componentes produtivos de cultivares de feijão comum de diversos grupos comerciais na época de safrinha
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