299 research outputs found
Locally Perturbed Random Walks with Unbounded Jumps
In \cite{SzT}, D. Sz\'asz and A. Telcs have shown that for the diffusively
scaled, simple symmetric random walk, weak convergence to the Brownian motion
holds even in the case of local impurities if . The extension of their
result to finite range random walks is straightforward. Here, however, we are
interested in the situation when the random walk has unbounded range.
Concretely we generalize the statement of \cite{SzT} to unbounded random walks
whose jump distribution belongs to the domain of attraction of the normal law.
We do this first: for diffusively scaled random walks on having finite variance; and second: for random walks with distribution
belonging to the non-normal domain of attraction of the normal law. This result
can be applied to random walks with tail behavior analogous to that of the
infinite horizon Lorentz-process; these, in particular, have infinite variance,
and convergence to Brownian motion holds with the superdiffusive scaling.Comment: 16 page
EINIGE PROBLEME DER W AHRSCHEINLICHKEITSVERTEILUNG VON PERIODISCH SYSTEMATISCHEN EINFLÜSSEN IN DER FERTIGUNGSMESSTECHNIK
On the changes of the electronic structure of early-transition-metal-systems at hydrogenation
The hydrogenation effect on Sc, Y, La, Cd and Eu has been investigated by XPS. The stability, the charge transfer as well as the microscopic behaviours of the processes have been discussed
Some relationships between the electron density of states and the metastable states of AlMgSi alloys
CLOSE-PACKED FRANK-KASPER COORDINATION AND HIGH CRITICAL TEMPERATURE SUPERCONDUCTIVITY
It has been proposed that a relation exists between close packed Frank-Kasper co-ordination in the layers containing Cu-O planes and high-Tc superconductivity. The origin of the superconductivity in perovskite-type materials is attributed in part to a three dimensional nesting of the Fermi-surface with the boundary of Jones-zone, causing 'partially-gapped' Fermi surface and to a gliding charge density wave arising from a three-dimensional 'breathing' of
distorted perovskite structures associated with close-packed seeking symmetry
On the protection of the isolation at the fabrication of all niobium josepshson-junctions
The protection mechanism of thin gold layer for preparation of all-niobium devices is
discussed. A suggestion on the electronic origin of protection is presented
Characterization of the nitrogen split interstitial defect in wurtzite aluminum nitride using density functional theory
We carried out Heyd-Scuseria-Ernzerhof hybrid density functional theory plane
wave supercell calculations in wurtzite aluminum nitride in order to
characterize the geometry, formation energies, transition levels and hyperfine
tensors of the nitrogen split interstitial defect. The calculated hyperfine
tensors may provide useful fingerprint of this defect for electron paramagnetic
resonance measurement.Comment: 5 pages, 3 figure
Theoretical model of the dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide
Dynamic nuclear spin polarization (DNP) mediated by paramagnetic point
defects in semiconductors is a key resource for both initializing nuclear
quantum memories and producing nuclear hyperpolarization. DNP is therefore an
important process in the field of quantum-information processing,
sensitivity-enhanced nuclear magnetic resonance, and nuclear-spin-based
spintronics. DNP based on optical pumping of point defects has been
demonstrated by using the electron spin of nitrogen-vacancy (NV) center in
diamond, and more recently, by using divacancy and related defect spins in
hexagonal silicon carbide (SiC). Here, we describe a general model for these
optical DNP processes that allows the effects of many microscopic processes to
be integrated. Applying this theory, we gain a deeper insight into dynamic
nuclear spin polarization and the physics of diamond and SiC defects. Our
results are in good agreement with experimental observations and provide a
detailed and unified understanding. In particular, our findings show that the
defects' electron spin coherence times and excited state lifetimes are crucial
factors in the entire DNP process
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