2,557 research outputs found

    Carbonate in soil: a theoretical consideration on, and proposal for its fabric analysis. 2. Crystal tubes, intercalary crystals, K fabric.

    Get PDF
    The spatial arrangement (fabric) of carbonate in 7 different soils was studied to make a proposal for its fabric analysis. These soils, which have been developed in calcareous loess and marine deposits, are located in Afghanistan, the USSR, Germany and the Netherlands.In the first part of this study (Bal, 1975) the simple plasmic fabrics crystic, calcic and fibrous have been defined. Their distinction is primarly based on theoretical considerations of Brewer's concepts (Brewer, 1964).In this second part the morphology and genesis of carbonate crystal tubes and intercalary carbonate crystals is dealt with.Also K-fabric, the carbonate fabric introduced by Gile et al. (1965) is discussed and redefined. The fabrics crystic, calcic and fibrous are simple fabrics; the K-fabric, on the contrary, is principally a compound fabric. This means that K fabric is composed of one or more of these simple fabrics. (Abstract retrieved from CAB Abstracts by CABI’s permission

    Carbonate in soil; a theoretical consideration on, and proposal for its fabric analysis. 1. Crystic, calcic and fibrous plasmic fabric.

    Get PDF
    The pedological features of seven soils formed in calcareous parent materials located in Afghanistan (serozem), USSR and Germany (chernozems), and in the Netherlands (marine deposits) are described. The distinction between the fabrics is based largely on Brewer's concept (1964). (Abstract retrieved from CAB Abstracts by CABI’s permission

    Kinetic Limit for Wave Propagation in a Random Medium

    Full text link
    We study crystal dynamics in the harmonic approximation. The atomic masses are weakly disordered, in the sense that their deviation from uniformity is of order epsilon^(1/2). The dispersion relation is assumed to be a Morse function and to suppress crossed recollisions. We then prove that in the limit epsilon to 0 the disorder averaged Wigner function on the kinetic scale, time and space of order epsilon^(-1), is governed by a linear Boltzmann equation.Comment: 71 pages, 3 figure

    Inverse Diffusion Theory of Photoacoustics

    Full text link
    This paper analyzes the reconstruction of diffusion and absorption parameters in an elliptic equation from knowledge of internal data. In the application of photo-acoustics, the internal data are the amount of thermal energy deposited by high frequency radiation propagating inside a domain of interest. These data are obtained by solving an inverse wave equation, which is well-studied in the literature. We show that knowledge of two internal data based on well-chosen boundary conditions uniquely determines two constitutive parameters in diffusion and Schroedinger equations. Stability of the reconstruction is guaranteed under additional geometric constraints of strict convexity. No geometric constraints are necessary when 2n2n internal data for well-chosen boundary conditions are available, where nn is spatial dimension. The set of well-chosen boundary conditions is characterized in terms of appropriate complex geometrical optics (CGO) solutions.Comment: 24 page

    Dynamics of parametric fluctuations induced by quasiparticle tunneling in superconducting flux qubits

    Full text link
    We present experiments on the dynamics of a two-state parametric fluctuator in a superconducting flux qubit. In spectroscopic measurements, the fluctuator manifests itself as a doublet line. When the qubit is excited in resonance with one of the two doublet lines, the correlation of readout results exhibits an exponential time decay which provides a measure of the fluctuator transition rate. The rate increases with temperature in the interval 40 to 158 mK. Based on the magnitude of the transition rate and the doublet line splitting we conclude that the fluctuation is induced by quasiparticle tunneling. These results demonstrate the importance of considering quasiparticles as a source of decoherence in flux qubits.Comment: 12 pages, including supplementary informatio

    An inceptisol formed in calcareous loess on the 'Dast-i-Esan Top' plain in North Afghanistan. Fabric, mineral and trace element analysis.

    Get PDF
    The calcixerollic xerochrept described has a low bulk density (1.1 g/cm3) which is attributed to faunal activity. The average mineral composition was 25% quartz, 20% CaCO3, 15% feldspars, 15% micas, 15% chlorites, 2-3% other minerals and 10% amorphous material and there was a clear relationship between minerals and particle size fractions. Trace element contents were 0.6, 11.0, 23.2, 49.1; 19.4, 75.9, 18.7 and 525 mg/kg for V, Cr, Co, Ni, Cu, Zn, Sr and Ba, respectively. Sr and Ba contents were related to carbonate redistribution. (Abstract retrieved from CAB Abstracts by CABI’s permission

    Phase Space Models for Stochastic Nonlinear Parabolic Waves: Wave Spread and Singularity

    Full text link
    We derive several kinetic equations to model the large scale, low Fresnel number behavior of the nonlinear Schrodinger (NLS) equation with a rapidly fluctuating random potential. There are three types of kinetic equations the longitudinal, the transverse and the longitudinal with friction. For these nonlinear kinetic equations we address two problems: the rate of dispersion and the singularity formation. For the problem of dispersion, we show that the kinetic equations of the longitudinal type produce the cubic-in-time law, that the transverse type produce the quadratic-in-time law and that the one with friction produces the linear-in-time law for the variance prior to any singularity. For the problem of singularity, we show that the singularity and blow-up conditions in the transverse case remain the same as those for the homogeneous NLS equation with critical or supercritical self-focusing nonlinearity, but they have changed in the longitudinal case and in the frictional case due to the evolution of the Hamiltonian

    Fluxon Dynamics of a Long Josephson Junction with Two-gap Superconductors

    Full text link
    We investigate the phase dynamics of a long Josephson junction (LJJ) with two-gap superconductors. In this junction, two channels for tunneling between the adjacent superconductor (S) layers as well as one interband channel within each S layer are available for a Cooper pair. Due to the interplay between the conventional and interband Josephson effects, the LJJ can exhibit unusual phase dynamics. Accounting for excitation of a stable 2Ï€\pi-phase texture arising from the interband Josephson effect, we find that the critical current between the S layers may become both spatially and temporally modulated. The spatial critical current modulation behaves as either a potential well or barrier, depending on the symmetry of superconducting order parameter, and modifies the Josephson vortex trajectories. We find that these changes in phase dynamics result in emission of electromagnetic waves as the Josephson vortex passes through the region of the 2Ï€\pi-phase texture. We discuss the effects of this radiation emission on the current-voltage characteristics of the junction.Comment: 14 pages, 6 figure
    • …
    corecore