4,029 research outputs found
Reparametrization Invariance and the Schr\"odinger Equation
In the present work we consider a time-dependent Schr\"odinger equation for
systems invariant under the reparametrization of time. We develop the two-stage
procedure of construction such systems from a given initial ones, which is not
invariant under the time reparametrization. One of the first-class constraints
of the systems in such description becomes the time-dependent Schr\"odinger
equation. The procedure is applicable in the supersymmetric theories as well.
The supersymmetric quantum mechanics is coupled to world-line
supergravity, and the local supersymmetric action is constructed leading to the
square root representation of the time-dependent Schr\"odinger equation.Comment: RevTeX,25 page
Multiple-orifice throttle valve
Multiple-orifice throttle valve is not subject to cold welding in a vacuum environment and is compatible with strong oxidizing fluid. The valve is of all metal construction using simple components that do not slide or rotate and excludes static or dynamic seals
Affine semigroups having a unique Betti element
We characterize affine semigroups having one Betti element and we compute
some relevant non-unique factorization invariants for these semigroups. As an
example, we particularize our description to numerical semigroups.Comment: 8 pages, 1 figure. To appear in Journal of Algebra and its
Application
Electron Confinement Induced by Diluted Hydrogen-like Ad-atoms in Graphene Ribbons
We report the electronic properties of two-dimensional systems made of
graphene nanoribbons which are patterned with ad-atoms in two separated
regions. Due to the extra electronic confinement induced by the presence of the
impurities, we find resonant levels, quasi-bound and impurity-induced localized
states, which determine the transport properties of the system. Regardless of
the ad-atom distribution in the system, we apply band-folding procedures to
simple models and predict the energies and the spatial distribution of those
impurity-induced states. We take into account two different scenarios: gapped
graphene and the presence of randomly distributed ad-atoms in a low dilution
regime. In both cases the defect-induced resonances are still detected. Our
findings would encourage experimentalist to synthesize these systems and
characterize their quasi-localized states employing, for instance, scanning
tunneling spectroscopy (STS). Additionally, the resonant transport features
could be used in electronic applications and molecular sensor devices.Comment: 12 pages, 11 figures, submitted (minor changes
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