9,643 research outputs found
Mechanism of temperature dependence of the magnetic anisotropy energy in ultrathin Cobalt and Nickel films
Temperature dependent FMR-measurements of Ni and Co films are analysed using
a microscopic theory for ultrathin metallic systems. The mechanism governing
the temperature dependence of the magnetic anisotropy energy is identified and
discussed. It is reduced with increasing temperature. This behavior is found to
be solely caused by magnon excitations.Comment: 3 pages, 4 figures III Joint European Magnetic Symposia, San
Sebastian, Spai
PMT Test Facility at MPIK Heidelberg and Double Chooz Super Vertical Slice
Proceedings supplement for conference poster at Neutrino 2010, Athens,
Greece
Spin wave excitations: The main source of the temperature dependence of Interlayer exchange coupling in nanostructures
Quantum mechanical calculations based on an extended Heisenberg model are
compared with ferromagnetic resonance (FMR) experiments on prototype trilayer
systems Ni_7/Cu_n/Co_2/Cu(001) in order to determine and separate for the first
time quantitatively the sources of the temperature dependence of interlayer
exchange coupling. Magnon excitations are responsible for about 75% of the
reduction of the coupling strength from zero to room temperature. The remaining
25% are due to temperature effects in the effective quantum well and the
spacer/magnet interfaces.Comment: accepted for publication in PR
Effective information and the influence of an extension event on perceptions and adoption
Perceptions are known to play an important role in the innovation adoption decision. Once influential perceptions have been identified, there is the potential for information to influence adoption by changing these perceptions. In this paper, the influence of an extension workshop targeting grain growers’ perceptions known to be associated with the adoption of integrated weed management and herbicide resistance management has been measured using regression analysis. Consistent with a Bayesian learning framework, the greatest influence on grower perceptions and intended adoption behaviour was observed where information could be delivered with a high degree of certainty and validity.Crop Production/Industries, Farm Management,
Parafermionic conformal field theory on the lattice
Finding the precise correspondence between lattice operators and the
continuum fields that describe their long-distance properties is a largely open
problem for strongly interacting critical points. Here we solve this problem
essentially completely in the case of the three-state Potts model, which
exhibits a phase transition described by a strongly interacting 'parafermion'
conformal field theory. Using symmetry arguments, insights from integrability,
and extensive simulations, we construct lattice analogues of nearly all the
relevant and marginal physical fields governing this transition. This
construction includes chiral fields such as the parafermion. Along the way we
also clarify the structure of operator product expansions between order and
disorder fields, which we confirm numerically. Our results both suggest a
systematic methodology for attacking non-free field theories on the lattice and
find broader applications in the pursuit of exotic topologically ordered phases
of matter.Comment: 27 pages, 4 figures; v2 added reference
The use of a Salmonella Typhimurium live vaccine to control Salmonella Typhimurium in fattening pigs in field and effects on serological surveillance
This field study was designed to evaluate the use of a live-attenuated Salmonella Typh1murium vaccine in pigs in respect of efficacy agamst S. Typhimurium at time of slaughter and the effect on serological herd monitoring using a commercial mixed LPS-ELISA. About 1289 slaughtered pigs (805 of non vaccinated groups and 484 of vaccinated groups) were investigated by bacteriological and serological examination (1149 pigs). The study showed the efficacy of an oral vaccination with a live-attenuated Salmonella Typhimunum vaccme in reducmg the number of Salmonella carrying pigs at slaughter without a detectable interference with the serological monitoring of Salmonella (using a cut off at 40% OD level)
Spatial stochastic resonance in 1D Ising systems
The 1D Ising model is analytically studied in a spatially periodic and
oscillatory external magnetic field using the transfer-matrix method. For low
enough magnetic field intensities the correlation between the external magnetic
field and the response in magnetization presents a maximum for a given
temperature. The phenomenon can be interpreted as a resonance phenomenon
induced by the stochastic heatbath. This novel "spatial stochastic resonance"
has a different origin from the classical stochastic resonance phenomenon.Comment: REVTex, 5 pages, 3 figure
A Formalism for Scattering of Complex Composite Structures. 2 Distributed Reference Points
Recently we developed a formalism for the scattering from linear and acyclic
branched structures build of mutually non-interacting sub-units.{[}C. Svaneborg
and J. S. Pedersen, J. Chem. Phys. 136, 104105 (2012){]} We assumed each
sub-unit has reference points associated with it. These are well defined
positions where sub-units can be linked together. In the present paper, we
generalize the formalism to the case where each reference point can represent a
distribution of potential link positions. We also present a generalized
diagrammatic representation of the formalism. Scattering expressions required
to model rods, polymers, loops, flat circular disks, rigid spheres and
cylinders are derived. and we use them to illustrate the formalism by deriving
the generic scattering expression for micelles and bottle brush structures and
show how the scattering is affected by different choices of potential link
positions.Comment: Paper no. 2 of a serie
Radiative Symmetry Breaking of the Minimal Left-Right Symmetric Model
Under the assumption of classical conformal invariance, we study the
Coleman-Weinberg symmetry breaking mechanism in the minimal left-right
symmetric model. This model is attractive as it provides a natural framework
for small neutrino masses and the restoration of parity as a good symmetry of
nature. We find that, in a large fraction of the parameter space, the parity
symmetry is maximally broken by quantum corrections in the Coleman-Weinberg
potential, which are a consequence of the conformal anomaly. As the left-right
symmetry breaking scale is connected to the Planck scale through the
logarithmic running of the dimensionless couplings of the scalar potential, a
large separation of the two scales can be dynamically generated. The symmetry
breaking dynamics of the model was studied using a renormalization group
analysis. Electroweak symmetry breaking is triggered by the breakdown of
left-right symmetry, and the left-right breaking scale is therefore expected in
the few TeV range. The phenomenological implications of the symmetry breaking
mechanism are discussed.Comment: 23 pages, 1 figure; version as published in journal; title changed,
changes in abstract, introduction and conclusion
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