14,046 research outputs found
The anomeric specificity of yeast galactokinase
Anomeric specificity of yeast galactokinase by chromatographic method
Exchange coupling between magnetic layers across non-magnetic superlattices
The oscillation periods of the interlayer exchange coupling are investigated
when two magnetic layers are separated by a metallic superlattice of two
distinct non-magnetic materials. In spite of the conventional behaviour of the
coupling as a function of the spacer thickness, new periods arise when the
coupling is looked upon as a function of the number of cells of the
superlattice. The new periodicity results from the deformation of the
corresponding Fermi surface, which is explicitly related to a few controllable
parameters, allowing the oscillation periods to be tuned.Comment: 13 pages; 5 figures; To appear in J. Phys.: Cond. Matte
NNLO predictions for Z-boson pair production at the LHC
We present a calculation of the NNLO QCD corrections to Z-boson pair
production at hadron colliders, based on the N-jettiness method for the real
radiation parts. We discuss the size and shape of the perturbative corrections
along with their associated scale uncertainties and compare our results to
recent LHC data at TeV.Comment: 19 pages, 2 Tables, 4 figures. Version to appear in JHE
Numerical evaluation of two-loop integrals with pySecDec
We describe the program pySecDec, which factorises endpoint singularities
from multi-dimensional parameter integrals and can serve to calculate integrals
occurring in higher order perturbative calculations numerically. We focus on
the new features and on frequently asked questions about the usage of the
program.Comment: 11 pages, to appear in the proceedings of the HiggsTools Final
Meeting, IPPP, University of Durham, UK, September 201
Analysis of the fluidization behaviour and application of a novel spouted bed\ud apparatus for spray granulation and coating
Spouted beds are well known for their good mixing of the solid phase and for their intensive heat\ud
and mass transfers between the fluid phase and the solid phase. Nearly isothermal conditions are\ud
enabled which is of advantage for the treatment of granular solid materials in granulation,\ud
agglomeration or coating processes. In this work the hydrodynamic behaviour of a novel spouted\ud
bed apparatus with two horizontal and slit-shaped gas inlets is investigated by high-frequency\ud
recordings of the gas phase pressure fluctuations over the entire bed. The hydrodynamic stable\ud
operation domain, which is of importance for operating the apparatus, will be identified and\ud
depicted in the Re-G-Ar-diagram by Mitev [1]. Another focus of this work is the simulation of the\ud
spouting process by application of a continuum approach in FLUENT 6.2. The effect of the\ud
frictional stresses on the hydrodynamic behaviour is examined by performing simulations with and\ud
without consideration of friction. The angle of internal friction fi in Schaeffer`s [10] model will be\ud
varied and the simulation results will be compared with experiments. It was found that the influence\ud
of friction is not very big by application of the quite simple and empirical frictional viscosity model\ud
by Schaeffer [10] basing on soil mechanical principles. Also the simulation results under negligence\ud
of friction were similar to those under consideration of friction. Another part of this work is the\ud
industrial application of the novel spouted bed in granulation and coating processes. Compared to\ud
classical fluidized beds, a much narrower particle size distribution, a higher yield and a higher\ud
product quality was obtained in the novel spouted be
SecDec-3.0: numerical evaluation of multi-scale integrals beyond one loop
SecDec is a program which can be used for the factorization of dimensionally
regulated poles from parametric integrals, in particular multi-loop integrals,
and the subsequent numerical evaluation of the finite coefficients. Here we
present version 3.0 of the program, which has major improvements compared to
version 2: it is faster, contains new decomposition strategies, an improved
user interface and various other new features which extend the range of
applicability.Comment: 46 pages, version to appear in Comput.Phys.Com
Effect of the liquid layer on the impact behaviour of particles
During a spray granulation process the moisture loading in fluidized beds has a great influence on\ud
the inter-particle collision properties and hence on the flow behaviour. To study the influence of the\ud
liquid layer as well as granule impact velocity on the impact behaviour free-fall experiments were\ud
performed. During these experiments the g-Al2O3 granules were dropped from a predefined height\ud
onto a liquid layer on the flat steel wall and the velocity-time curves were obtained using highspeed\ud
video recording. The height of the liquid layer was varied from 50 mm to 1 mm. Moreover,\ud
the tests were performed at different velocities and viscosities of liquid layer in the range of 1-300\ud
mPaâs. Both distilled water and water solutions of hydroxypropyl methylcellulose with different\ud
concentrations (3, 6, 10 mass-%) were used.\ud
The obtained restitution coefficients were compared with the experiments performed without liquid\ud
film on the surface. For a granule impacted on a liquid film on the wall, the increase of liquid\ud
viscosity decreases the restitution coefficient and thickness of liquid layer at which the granule\ud
sticks. In the examined velocity range, with decreasing impact velocity the restitution coefficient\ud
greatly decreases. To explain the obtained effects the force and energy balances for a particle\ud
impacted on a liquid layer on the wall were derived. Both contributions to energy absorption\ud
(granule-liquid layer and granule-wall contacts) have been taken into consideratio
NLO predictions for Higgs boson pair production with full top quark mass dependence matched to parton showers
We present the first combination of NLO QCD matrix elements for di-Higgs
production, retaining the full top quark mass dependence, with a parton shower.
Results are provided within both the POWHEG-BOX and MadGraph5_aMC@NLO Monte
Carlo frameworks. We assess in detail the theoretical uncertainties and provide
differential results. We find that, as expected, the shower effects are
relatively large for observables like the transverse momentum of the Higgs
boson pair, which are sensitive to extra radiation. However, these shower
effects are still much smaller than the differences between the Born-improved
HEFT approximation and the full NLO calculation in the tails of the
distributions.Comment: replaced by published version; in addition typos corrected in
definition of pole coefficients below Eq.(2.4
Gilbert Damping in Magnetic Multilayers
We study the enhancement of the ferromagnetic relaxation rate in thin films
due to the adjacent normal metal layers. Using linear response theory, we
derive the dissipative torque produced by the s-d exchange interaction at the
ferromagnet-normal metal interface. For a slow precession, the enhancement of
Gilbert damping constant is proportional to the square of the s-d exchange
constant times the zero-frequency limit of the frequency derivative of the
local dynamic spin susceptibility of the normal metal at the interface.
Electron-electron interactions increase the relaxation rate by the Stoner
factor squared. We attribute the large anisotropic enhancements of the
relaxation rate observed recently in multilayers containing palladium to this
mechanism. For free electrons, the present theory compares favorably with
recent spin-pumping result of Tserkovnyak et al. [Phys. Rev. Lett.
\textbf{88},117601 (2002)].Comment: 1 figure, 5page
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