7,507 research outputs found
Epithelial character and morphological diversity of cell cultures from human amnotic fluids examined by immunofluorescence microscopy and gel electrophoresis of cytoskeletal proteins
POLLUTION DISPERSION PREDICTION FOR THE MUST WIND TUNNEL EXPERIMENT WITH ANISOTROPIC ALGEBRAIC MODELS FOR TURBULENT SCALAR FLUXES
The numerical prediction of pollution dispersion in urban environments by means of solution of the statistically steady
Reynolds Averaged Navier Stokes (RANS) equations is known to be strongly dependent on the turbulence models. In the case of
pollution dispersion turbulence models do not only have to be used for the Reynolds stresses but also for the turbulent scalar fluxes.
While the influence of several turbulence models for the Reynolds stresses on the dispersion in urban environments has been
examined already several times, the turbulent scalar fluxes were exclusively modelled by the simple gradient diffusion assumption.
In the present work therefore the influence of more advanced, anisotropic algebraic models for the turbulent scalar fluxes on the
dispersion in the MUST wind tunnel experiment is examined. To that end, three anisotropic algebraic flux models were
implemented in the commercial software FLUENT 6.3. All these models together with the simple gradient diffusion model (with
two turbulent Schmidt numbers) are performed and compared using statistical performance measures to assess their predictive
capability
Ion hopping in crystalline and glassy spodumene LiAlSi2O6: Li7 spin-lattice relaxation and Li7 echo NMR spectroscopy
Nuclear magnetic resonance spectroscopy was used to study polycrystalline β-spodumene (β−LiAlSi2O6) as well as glassy specimens with the same chemical composition. 7Li spin-lattice relaxation measurements were carried out in a broad temperature range and for several Larmor frequencies. In addition to a pronounced rate maximum at high temperatures, stemming from the long-range Li motion in these aluminosilicates, we found a weak maximum in the crystalline modification near 120K. The latter result confirms the existence of a local double-well structure in which the Li ions reside. The ionic motion was also monitored by solid- and stimulated-echo spectra as well as by the decay of the Jeener-Broekaert echo. Under conditions which are discussed in detail, the latter is a direct measure of the hopping correlation function. For the glass this function was found to decay faster and more stretched than that of the crystal at a given temperature. Furthermore, the relevant barriers against the high-temperature long-range Li motion are larger in the crystal as compared to the glass. © 2005 The American Physical Society
Increasing the dimension in high-dimensional two-photon orbital angular momentum entanglement
Any practical experiment utilising the innate D-dimensional entanglement of
the orbital angular momentum (OAM) state space of photons is subject to the
modal capacity of the detection system. We show that given such a constraint,
the number of measured, entangled OAM modes in photon pairs generated by
spontaneous parametric down-conversion (SPDC) can be maximised by tuning the
phase-matching conditions in the SPDC process. We demonstrate a factor of 2
increase on the half-width of the OAM-correlation spectrum, from 10 to 20, the
latter implying \approx 50 -dimensional two-photon OAM entanglement. Exploiting
correlations in the conjugate variable, angular position, we measure
concurrence values 0.96 and 0.90 for two phase-matching conditions, indicating
bipartite, D-dimensional entanglement where D is tuneable
Comparison of quantum field perturbation theory for the light front with the theory in lorentz coordinates
The relationship between the perturbation theory in light-front coordinates
and Lorentz-covariant perturbation theory is investigated. A method for finding
the difference between separate terms of the corresponding series without their
explicit evaluation is proposed. A procedure of constructing additional
counter-terms to the canonical Hamiltonian that compensate this difference at
any finite order is proposed. For the Yukawa model, the light-front Hamiltonian
with all of these counter-terms is obtained in a closed form. Possible
application of this approach to gauge theories is discussed.Comment: LaTex 2.09, 20 pages, 5 figure
Organization of desmosomal plaque proteins in cells growing at low calcium concentrations.
Ferromagnetic coupling of mononuclear Fe centers in a self-assembled metal-organic network on Au(111)
The magnetic state and magnetic coupling of individual atoms in nanoscale
structures relies on a delicate balance between different interactions with the
atomic-scale surrounding. Using scanning tunneling microscopy, we resolve the
self-assembled formation of highly ordered bilayer structures of Fe atoms and
organic linker molecules (T4PT) when deposited on a Au(111) surface. The Fe
atoms are encaged in a three-dimensional coordination motif by three T4PT
molecules in the surface plane and an additional T4PT unit on top. Within this
crystal field, the Fe atoms retain a magnetic ground state with easy-axis
anisotropy, as evidenced by X-ray absorption spectroscopy and X-ray magnetic
circular dichroism. The magnetization curves reveal the existence of
ferromagnetic coupling between the Fe centers
A New 80kV/14kA Solid State Thyristor Crowbar for the Commissioning and Testing of Vacuum Power Tubes in Fusion Research at IPP Garching
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