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FLUX MAPPING AND MAGNETIC BEHAVIOR OF GRAIN BOUNDARIES IN ND-FE-B MAGNETS.
Synchronizing automata with random inputs
We study the problem of synchronization of automata with random inputs. We
present a series of automata such that the expected number of steps until
synchronization is exponential in the number of states. At the same time, we
show that the expected number of letters to synchronize any pair of the famous
Cerny automata is at most cubic in the number of states
Proximity-induced transport in hybrid mesoscopic normal-superconducting metal structures
Using an approach based on quasiclassical Green's functions we present a
theoretical study of transport in mesoscopic S/N structures in the diffusive
limit. The subgap conductance in S/N structures with barriers (zero bias and
finite bias anomalies) are discused. We also analyse the temperature dependence
of the conductance variation for a Andreev interferometer. We
show that besides the well know low temperature maximum a second maximum near
may appear. We present the results of studies on the Josephson effect in
4 terminal S/N/S contacts and on the possible sign reversal of the Josephson
critical current.Comment: 8 pages, 5 figures, with added refrence
Quasifission at extreme sub-barrier energies
With the quantum diffusion approach the behavior of the capture cross-section
is investigated in the reactions Mo + Mo, Ru +
Ru, Pd + Pd, and Kr + Sn at deep
sub-barrier energies which are lower than the ground state energies of the
compound nuclei. Because the capture cross section is the sum of the complete
fusion and quasifission cross sections, and the complete fusion cross section
is zero at these sub-barrier energies, one can study experimentally the unique
quasifission process in these reactions after the capture.Comment: 3 pages, 3 figure
Solitons and black holes in non-Abelian Einstein-Born-Infeld theory
Recently it was shown that the Born-Infeld-type modification of the quadratic
Yang-Mills action gives rise to classical particle-like solutions in the flat
space which have a striking similarity with the Bartnik-McKinnon solutions
known in the gravity coupled Yang-Mills theory. We show that both families are
continuously related within the framework of the Einstein-Born-Infeld theory
through interpolating sequences of parameters. We also investigate an internal
structure of the associated black holes. It is found that the Born-Infeld
non-linearity leads to a drastic modification of the black hole interior
typical for the usual Yang-Mills theory. In the latter case a generic solution
exhibits violent metric oscillations near the singularity. In the Born-Infeld
case a generic interior solution is smooth, the metric has the standard
Schwarzschild type singularity, and we did not observe internal horizons. Such
smoothing of the 'violent' EYM singularity may be interpreted as a result of
quantum effects.Comment: Latex, 9 pages, 9 eps figure
Treatment of competition between complete fusion and quasifission in collisions of heavy nuclei
A model of competition between complete fusion and quasifission channels in
fusion of two massive nuclei is extended to include the influence of
dissipative effects on the dynamics of nuclear fusion. By using the
multidimensional Kramers-type stationary solution of the Fokker-Planck
equation, the fusion rate through the inner fusion barrier in mass asymmetry is
studied. Fusion probabilities in symmetric 90Zr+90Zr, 100Mo+100Mo, 110Pd+110Pd,
136Xe+136Xe, almost symmetric 86Kr+136Xe and 110Pd+136Xe reactions are
calculated. An estimation of the fusion probabilities is given for asymmetrical
62Ni+208Pb, 70Zn+208Pb, 82Se+208Pb, and 48Ca+244Pu reactions used for the
synthesis of new superheavy elements.Comment: 29 pages, LaTeX, including 7 postscript figures, to appear in Nucl.
Phys.
Fusion cross sections for superheavy nuclei in the dinuclear system concept
Using the dinuclear system concept we present calculations of production
cross sections for the heaviest nuclei. The obtained results are in a good
agreement with the experimental data. The experimentally observed rapid
fall-off of the cross sections of the cold fusion with increasing charge number
of the compound nucleus is explained. Optimal experimental conditions for
the synthesis of the superheavy nuclei are suggested.Comment: 16 pages, LaTeX, including 3 postscript figure
Complexity of checking whether two automata are synchronized by the same language
A deterministic finite automaton is said to be synchronizing if it has a
reset word, i.e. a word that brings all states of the automaton to a particular
one. We prove that it is a PSPACE-complete problem to check whether the
language of reset words for a given automaton coincides with the language of
reset words for some particular automaton.Comment: 12 pages, 4 figure
Ferromagnetic domain structures and spin configurations measured in doped manganite
We report on measurements of the spin configuration across ferromagnetic domains in La(0.325)Pr(0.3)Ca(0.375)MnO(3) films obtained by means of low-temperature Lorentz electron microscopy with in situ magnetizing capabilities. Due to the particular crystal symmetry of the material, we observe two sets of independent ferromagnetic twin variants, one of which was pinned by crystallographic twinning. The spin orientation and configuration of the domains were measured quantitatively using electron diffraction and electron holography, and verified with structural modeling. The observed deviation of spin orientations from the expected 90 degrees head-to-tail configuration across the domain walls was attributed to the variation in the domains' aspect ratios as a result of the demagnetization field. Our study provides important insight on how the spin configuration coupled with the magnetic structure and the crystal symmetry might affect the magnetoresistivity under an applied magnetic field in a strongly correlated electron system
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