24,493 research outputs found

    Construction Accounting

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    Management Organizational Behavior: an integrated perspective

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    Management and Organizational Behavior: An Integrated Perspective blends traditional management and organizational behavior topics in a unique, integrative model. The text emphasizes how managers must understand the organization, the management process, individuals as members, and the deep interrelationship among all of these areas

    The structure of quantum Lie algebras for the classical series B_l, C_l and D_l

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    The structure constants of quantum Lie algebras depend on a quantum deformation parameter q and they reduce to the classical structure constants of a Lie algebra at q=1q=1. We explain the relationship between the structure constants of quantum Lie algebras and quantum Clebsch-Gordan coefficients for adjoint x adjoint ---> adjoint. We present a practical method for the determination of these quantum Clebsch-Gordan coefficients and are thus able to give explicit expressions for the structure constants of the quantum Lie algebras associated to the classical Lie algebras B_l, C_l and D_l. In the quantum case also the structure constants of the Cartan subalgebra are non-zero and we observe that they are determined in terms of the simple quantum roots. We introduce an invariant Killing form on the quantum Lie algebras and find that it takes values which are simple q-deformations of the classical ones.Comment: 25 pages, amslatex, eepic. Final version for publication in J. Phys. A. Minor misprints in eqs. 5.11 and 5.12 correcte

    A quest for frustration driven distortion in Y2Mo2O7

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    We investigated the nature of the freezing in the geometrically frustrated Heisenberg spin-glass Y2Mo2O7 by measuring the temperature dependence of the static internal magnetic field distribution above the spin-glass temperature, Tg, using the muSR technique. The evolution of the field distribution cannot be explained by changes in the spin susceptibility alone and suggests a lattice deformation. This possibility is addressed by numerical simulations of the Heisenberg Hamiltonian with magneto-elastic coupling at T>0.Comment: 5 pages 4 figures. Accepted for publication in PR

    Daytime lidar measurements of tidal winds in the mesospheric sodium layer at Urbana, Illinois

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    For more than 15 years lidar systems have been used to study the chemistry and dynamics of the mesospheric sodium layer. Because the layer is an excellent tracer of atmospheric wave motions, sodium lidar has proven to be particularly useful for studying the influence of gravity waves and tides on mesospheric dynamics. These waves, which originate in the troposphere and stratosphere, propagate through the mesosphere and dissipate their energy near the mesopause making important contributions to the momentum and turbulence budget in this region of the atmosphere. Recently, the sodium lidar was modified for daytime operation so that wave phenomena and chemical effects could be monitored throughout the complete diurnal cycle. The results of continuous 24 hour lidar observations of the sodium layer structure are presented alond with measurement of the semidiurnal tidal winds

    Spatial variations in the sulfur chemistry of salt marsh sediments at North Inlet, South Carolina

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    Profiles of particulate and dissolved sulfur species have been measured in marsh sediments along three transects across the various growth zones (tall, medium and short) of Spartina alterniflora. In general, organic carbon, total sulfur, pyritic sulfur, pyritization index and dissolved sulfide increased with distance from tidal creek banks, whereas acid volatile sulfur (FeS), pH and Eh decreased with distance. These patterns probably are controlled by spatial variations in belowground production, pore water movement and fiddler crab burrowing. The creekside marsh (tall Spartina) is characterized by lower rates of belowground production (and thus lower rates of sulfate reduction and sulfide production), more vigorous drainage of pore water and more intense fiddler crab burrowing as compared to the high marsh (short Spartina). Lower dissolved sulfide concentrations in the creekside marsh are promoted by lower rates of sulfate reduction and removal of dissolved sulfide by drainage at low tide. Higher pH in the creekside marsh is fostered by removal of reduced sulfur (dissolved sulfide by drainage and pyrite by fiddler crab burrowing) which then cannot be oxidized in the sediment to yield acid. The higher pH and lower dissolved sulfide of the creekside marsh, in turn, slow rate of conversion of iron oxide into pyrite in accordance with Rickard\u27s (1974, 1975) rate laws and thus foster a lower pyritization index. The lower pyritization index of the creekside marsh also is promoted by fiddler crab burrowing which removes pyrite from the sediment and replaces it with fresh iron oxide from the surface or suspended source. Finally the greater availability of reactive iron oxide in the creekside marsh may shift the relative rates of FeS and FeS2 formation such that a higher steady state concentration of FeS can be maintained there as compared to the high marsh

    Correlated patterns in non-monotonic graded-response perceptrons

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    The optimal capacity of graded-response perceptrons storing biased and spatially correlated patterns with non-monotonic input-output relations is studied. It is shown that only the structure of the output patterns is important for the overall performance of the perceptrons.Comment: 4 pages, 4 figure

    Absence of anomalous negative lattice-expansion for polycrystalline sample of Tb2Ti2O7

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    High resolution X-ray powder-diffraction experiments on a well-characterized polycrystalline sample of the spin liquid Tb2Ti2O7 reveal that it shows normal positive thermal-expansion above 4 K, which does not agree with the intriguing anomalous negative thermal-expansion due to a magneto-elastic coupling reported for a single crystal sample below 20 K. We also performed a Rietveld profile refinement of a powder-diffraction pattern taken at a room temperature, and confirmed that it is consistent with the fully ordered cubic pyrochlore structure.Comment: 2 pages, 3 figure
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