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Tuberculous Pericarditis
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Currents and pseudomagnetic fields in strained graphene rings
We study the effects of strain on the electronic properties and persistent
current characteristics of a graphene ring using the Dirac representation. For
a slightly deformed graphene ring flake, one obtains sizable pseudomagnetic
(gauge) fields that may effectively reduce or enhance locally the applied
magnetic flux through the ring. Flux-induced persistent currents in a flat ring
have full rotational symmetry throughout the structure; in contrast, we show
that currents in the presence of a circularly symmetric deformation are
strongly inhomogeneous, due to the underlying symmetries of graphene. This
result illustrates the inherent competition between the `real' magnetic field
and the `pseudo' field arising from strains, and suggest an alternative way to
probe the strength and symmetries of pseudomagnetic fields on graphene systems
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Analytical treatment of stabilization
We present a summarizing account of a series of investigations whose central topic is to address the question whether atomic stabilization exists in an analytical way. We provide new aspects on several issues of the matter in the theoretical context when the dynamics is described by the Stark Hamiltonian. The main outcome of these studies is that the governing parameters for this phenomenon are the total classical momentum transfer and the total classical displacement. Whenever these two quantities vanish, asymptotically weak stabilization does exist. For all other situations we did not find any evidence for stabilization. We found no evidence that strong stabilization might occur. Our results agree qualitatively with the existing experimental findings
The quantum brachistochrone problem for non-Hermitian Hamiltonians
Recently Bender, Brody, Jones and Meister found that in the quantum brachistochrone problem the passage time needed for the evolution of certain initial states into specified final states can be made arbitrarily small, when the time-evolution operator is taken to be non-Hermitian but PT-symmetric. Here we demonstrate that such phenomena can also be obtained for non-Hermitian Hamiltonians for which PT-symmetry is completely broken, i.e. dissipative systems. We observe that the effect of a tunable passage time can be achieved by projecting between orthogonal eigenstates by means of a time-evolution operator associated with a non-Hermitian Hamiltonian. It is not essential that this Hamiltonian is PT-symmetric
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