2,061,740 research outputs found
Steps in the Negative-Differential-Conductivity Regime of a Superconductor
Current-voltage characteristics were measured in the mixed state of
Y1Ba2Cu3O(7-delta) superconducting films in the regime where flux flow becomes
unstable and the differential conductivity dj/dE becomes negative. Under
conditions where its negative slope is steep, the j(E) curve develops a
pronounced staircase like pattern. We attribute the steps in j(E) to the
formation of a dynamical phase consisting of the succesive nucleation of
quantized distortions in the local vortex velocity and flux distribution within
the moving flux matter.Comment: 5 pages, 3 figure
Cyclically presented modules, projective covers and factorizations
We investigate projective covers of cyclically presented modules,
characterizing the rings over which every cyclically presented module has a
projective cover as the rings that are Von Neumann regular modulo their
Jacobson radical and in which idempotents can be lifted modulo .
Cyclically presented modules naturally appear in the study of factorizations of
elements in non-necessarily commutative integral domains. One of the possible
applications is to the modules whose endomorphism ring is Von
Neumann regular modulo and in which idempotents lift modulo .Comment: 17 page
- …