3,974 research outputs found
Exploratory electromagnetic thruster research, phase 3, 23 June - 23 December 1969
Performance evaluation of MPD arc jets operating in quasi-steady mode
Investigation of pulsed quasi-steady MPD arc jets
Evaluation of magnetohydrodynamic arc thrusters operating in quasi-steady mode with electrode vapor as propellan
Identification of a vesicular glutamate transporter that defines a glutamatergic phenotype in neurons.
Instantons and Monopoles in General Abelian Gauges
A relation between the total instanton number and the quantum-numbers of
magnetic monopoles that arise in general Abelian gauges in SU(2) Yang-Mills
theory is established. The instanton number is expressed as the sum of the
`twists' of all monopoles, where the twist is related to a generalized Hopf
invariant. The origin of a stronger relation between instantons and monopoles
in the Polyakov gauge is discussed.Comment: 28 pages, 8 figures; comments added to put work into proper contex
Synaptic vesicles are constitutively active fusion machines that function independently of Ca<sup>2+</sup>.
Density functional electronic spectrum of the cluster and possible local Jahn-Teller distorsions in the La-Ba-Cu-O superconductor
We present a density functional theory (DFT) calculation in the generalized
gradient approximation to study the possibility for the existence of
Jahn-Teller (JT) or pseudo Jahn-Teller (PJT) type local distortions in the
La-Ba-Cu-O superconducting system. We performed the calculation and
correspondingly group theory classification of the electronic ground state of
the CuO elongated octahedra cluster, immersed in a background
simulating the superconductor. Part of the motivation to do this study is that
the origin of the apical deformation of the CuO cluster is not
due to a pure JT effect, having therefore a non {\it a priori} condition to
remove the degeneracy of the electronic ground state of the parent regular
octahedron. We present a comparative analysis of the symmetry classified
electron spectrum with previously reported results using unrestricted
Hartree-Fock calculations (UHF). Both the DFT and UHF calculations produced a
non degenerate electronic ground state, not having therefore the necessary
condition for a pure JT effect. However, the appearance of a degenerate E
state near to the highest occupied molecular orbital in the DFT calculation,
suggests the possibility for a PJT effect responsible for a local distortion of
the oxidized CuO cluster.Comment: 12 pages, 3 figures, submitted to International Journal of Modern
Physics B (IJMPB
Exploratory electromagnetic thruster research Annual report
Glass fiber, cylindrical vacuum tank for electromagnetic thrustor researc
Jahn-Teller stabilization of a "polar" metal oxide surface: Fe3O4(001)
Using ab initio thermodynamics we compile a phase diagram for the surface of
Fe3O4(001) as a function of temperature and oxygen pressures. A hitherto
ignored polar termination with octahedral iron and oxygen forming a wave-like
structure along the [110]-direction is identified as the lowest energy
configuration over a broad range of oxygen gas-phase conditions. This novel
geometry is confirmed in a x-ray diffraction analysis. The stabilization of the
Fe3O4(001)-surface goes together with dramatic changes in the electronic and
magnetic properties, e.g., a halfmetal-to-metal transition.Comment: 4 pages, 4 figure
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