2,675 research outputs found

    Holocene Sediment Magnetic Properties Along a Transect from Isafjardardjup to Djupall, Northwest Iceland

    Full text link
    Holocene changes in terrestrial provenance and processes of sediment transport and deposition are tracked along a fjord-to-shelf transect adjacent to Vestfirdir, Iceland, using the magnetic properties ofmarine sediments.Magnetic susceptibility (MS) profiles of 10 cores (gravity and piston) were obtained onboard using a Bartington MS loop. Remanent magnetizations were measured at 1-cm intervals from u-channel samples taken from six cores on a cryogenic magnetometer. Between six and nine alternating field demagnetization steps were used to isolate the characteristic magnetization directions. The chronologies of the cores used in this study were determined from AMS14 C dates on mollusks and foraminifera and contrained by the regional occurrance ofthe 10,200 6 60 cal yr. BP Saksunavatn tepha. Correlative fluctuations in magneticconcentration are noted between the fjord and shelf sites, though these fluctuations are partiallymasked by regional variations in carbonate content. The onset of Neoglaciation is interpreted by changes in magnetic properties including an increase in mass magneticsusceptibility that began approximately 3000 cal yr. BP. The maximum angular deviation and the median destructive field (generally 20 mT) suggest that the natural remanent magnetization is carried by a coarse ferrimagnetite mineralogy, likely magnetite or titano-magnetite. Reproducible paleomagnetic inclination values are observed in several records, including a nearly vertical inclination around 8000 cal yr. BP, suggesting that the magnetic pole may have been proximal to Iceland, followed by an interval of much shallower inclination (6000–7000 cal yr. BP)

    Determining density of maize canopy. 2: Airborne multispectral scanner data

    Get PDF
    Multispectral scanner data were collected in two flights over a light colored soil background cover plot at an altitude of 305 m. Energy in eleven reflective wavelength band from 0.45 to 2.6 microns was recorded. Four growth stages of maize (Zea mays L.) gave a wide range of canopy densities for each flight date. Leaf area index measurements were taken from the twelve subplots and were used as a measure of canopy density. Ratio techniques were used to relate uncalibrated scanner response to leaf area index. The ratios of scanner data values for the 0.72 to 0.92 micron wavelength band over the 0.61 to 0.70 micron wavelength band were calculated for each plot. The ratios related very well to leaf area index for a given flight date. The results indicated that spectral data from maize canopies could be of value in determining canopy density

    Comparing soil boundaries delineated by digital analysis of multispectral scanner data from high and low spatial resolution systems

    Get PDF
    The author has identified the following significant results. Computer-aided analysis techniques used with aircraft MSS data showed that the spatial resolution was sufficient to recognize each soil mapping unit of the test site. Some difficulties occurred where different soil series were intricately mixed, and this mixture showed as a separate spectral mapping unit, or where the difference between two soils depended on the depth of silty surface material. Analysis of LANDSAT data with computer-aided techniques showed that it was not possible to find spectrally homogeneous soil features of the seven soil series on the 40 ha test site on the digital display or on a picture print map. Cluster techniques could be used on an extended test area to group spectrally similar data points into cluster classes

    Embedding generic employability skills in an accounting degree: development and impediments

    Get PDF
    This paper explores and analyses the views of, and effects on, students of a project that integrated the development of employability skills within the small group classes of two compulsory courses in the first year of an accounting degree at a UK university. The project aimed to build, deliver and evaluate course materials designed to encourage the development of a broad range of employability skills: skills needed for life-long learning and a successful business career. By analysing students' opinions gathered from a series of focus groups spread throughout the year, three prominent skill areas of interest were identified: time management, modelling, and learning to learn. Further analysis highlighted the complex nature of skills development, and brought to light a range of impediments and barriers to both students' development of employability skills and their subject learning. The analysis suggests the need for accounting educators to see skills development as being an essential element of the path to providing a successful accounting education experience

    Magnetism of 3d transition metal atoms on W(001): submonolayer films

    Full text link
    We have investigated random submonolayer films of 3d transition metals on W(001). The tight-binding linear muffin-tin orbital method combined with the coherent potential approximation was employed to calculate the electronic structure of the films. We have estimated local magnetic moments and the stability of different magnetic structures, namely the ferromagnetic order, the disordered local moments and the non-magnetic state, by comparing the total energies of the corresponding systems. It has been found that the magnetic moments of V and Cr decrease and eventually disappear with decreasing coverage. On the other hand, Fe retains approximately the same magnetic moment throughout the whole concentration range from a single impurity to the monolayer coverage. Mn is an intermediate case between Cr and Fe since it is non-magnetic at very low coverages and ferromagnetic otherwise.Comment: 5 pages, 3 figures in 6 files; presented at ICN&T 2006, Basel, Switzerlan

    Hysteretic properties of a magnetic particle with strong surface anisotropy

    Full text link
    We study the influence of surface anisotropy on the zero-temperature hysteretic properties of a small single-domain magnetic particle, and give an estimation of the anisotropy constant for which deviations from the Stoner-Wohlfarth model are observed due to non-uniform reversal of the particle's magnetisation. For this purpose, we consider a spherical particle with simple cubic crystalline structure, a uniaxial anisotropy for core spins and radial anisotropy on the surface. The hysteresis loop is obtained by solving the local (coupled) Landau-Lifschitz equations for classical spin vectors. We find that when the surface anisotropy constant is at least of the order of the exchange coupling, large deviations are observed with respect to the Stoner-Wohlfarth model in the hysteresis loop and thereby the limit-of-metastability curve, since in this case the magnetisation reverses its direction in a non-uniform manner via a progressive switching of spin clusters. In this case the critical field, as a function of the particle's size, behaves as observed in experiments.Comment: 12 pages, 15 eps figure

    Effects of Bradykinin and Indomethacin on Cyclic GMP and Cyclic AMP in Lung Slices

    Full text link

    Stumbling Down the Courthouse Steps: Mediators\u27 Perceptions of the Stumbling Blocks to Successful Mandated Mediation in Child Custody and Visitation

    Get PDF
    Although many concerns and criticisms about the efficacy of family law mediation have been made by attorneys, judges, and psychologists, we seldom hear from the mediators themselves about how the process works. In this study, we examine the mediators\u27 perceptions of the stumbling blocks to success in mandatory child custody mediation and make some recommendations about how the process might be improved

    Spin Josephson effect in ferromagnet/ferromagnet tunnel junctions

    Full text link
    We consider the tunnel spin current between two ferromagnetic metals from a perspective similar to the one used in superconductor/superconductor tunnel junctions. We use fundamental arguments to derive a Josephson-like spin tunnel current IJspinsin(θ1θ2)I_J^{\rm spin}\propto\sin(\theta_1-\theta_2). Here the phases are associated with the planar contribution to the magnetization, eiθ\sim e^{i\theta}. The crucial step in our analysis is the fact that the zz-component of the spin is canonically conjugate to the phase of the planar contribution: [θ,Sz]=i[\theta,S^z]=i. This is analogous to the commutation relation [ϕ,N]=i[\phi,N]=i in superconductors, where ϕ\phi is the phase associated to the superconducting order parameter and NN is the Cooper pair number operator. We briefly discuss the experimental consequences of our theoretical analysis.Comment: LaTex, seven pages, no figures; version to appear in Europhys. Lett.; in order to make room for a more extended microscopic analysis, the phenomenological discussion contained in v2 was remove
    corecore