2,271 research outputs found
The Dirac point electron in zero-gravity Kerr--Newman spacetime
Dirac's wave equation for a point electron in the topologically nontrivial
maximal analytically extended electromagnetic Kerr--Newman spacetime is studied
in a zero-gravity limit; here, "zero-gravity" means , where is
Newton's constant of universal gravitation. The following results are obtained:
the formal Dirac Hamiltonian on the static spacelike slices is essentially
self-adjoint; the spectrum of the self-adjoint extension is symmetric about
zero, featuring a continuum with a gap about zero that, under two smallness
conditions, contains a point spectrum. Some of our results extend to a
generalization of the zero- Kerr--Newman spacetime with different
electric-monopole-to-magnetic-dipole-moment ratio.Comment: 49 pages, 17 figures; referee's comments implemented; the endnotes in
the published version appear as footnotes in this preprin
Role of the top management team in post-acquisition success: A resource-based view.
This research focuses on the TMT, their retention, the particular characteristics of the TMT (their networks, knowledge, dynamic capability), these characteristics moderated by both acquisition type and competitive environment, and their value to the acquiring firm to help explain the variation in post-acquisition success of the acquired firm. Finally, this research focuses on smaller acquisitions, which are the majority as opposed to most previous research that focused on larger acquisitions only. This research also examines primary data from acquisition managers as opposed to the secondary (archival) data that has dominated most previous work on acquisitions.Our findings suggest that Pre-Acquisition performance of the target firm correlates with top management team (TMT) retention. Higher TMT retention was found to positively correlate with Post-Acquisition performance and that Pre-Acquisition performance does not correlate with post-acquisition performance. TMT knowledge, TMT network and TMT dynamic capability were found to be positively significant to post-acquisition performance. We controlled for the size of the acquirer versus the acquired, how the firm was purchased and the type of ownership of the acquired firm.The acquisition strategy is likely the most popular corporate strategy for growth. Research continues to explore this strategy and suggest that acquisitions occur for numerous reasons: rapid renewal in a global marketplace, creating synergies, ensuring financial and tax advantages, establishing market power, and the market for corporate control. However, a large body of research suggests that top management team (TMT) failure and improvement in efficiency is the key role for acquisitions, as argued in the market for corporate control literature. An important research question that researchers continue to explore is the disposition of the TMT subsequent to acquisition and its impact on acquisition performance
Ground State H-Atom in Born-Infeld Theory
Within the context of Born-Infeld (BI) nonlinear electrodynamics (NED) we
revisit the non-relativistic, spinless H-atom. The pair potential computed from
the Born-Infeld equations is approximated by the Morse type potential with
remarkable fit over the critical region where the convergence of both the short
and long distance expansions slows down dramatically. The Morse potential is
employed to determine both the ground state energy of the electron and the BI
parameter.Comment: 4 pages, 1 figure, final version to appear in Foundation of Physic
Superconductivity in metal rich Li-Pd-B ternary Boride
8K superconductivity was observed in the metal rich Li-Pd-B ternary system.
Structural, microstructural, electrical and magnetic investigations for various
compositions proved that Li2Pd3B compound, which has a cubic structure composed
of distorted Pd6B octahedrons, is responsible for the superconductivity. This
is the first observation of superconductivity in metal rich ternary borides
containing alkaline metal and Pd as a late transition metal. The compound
prepared by arc melting has high density, is stable in the air and has an upper
critical field, Hc2(0), of 6T.Comment: 4 pages, 5 figur
The linear Fokker-Planck equation for the Ornstein-Uhlenbeck process as an (almost) nonlinear kinetic equation for an isolated N-particle system
It is long known that the Fokker-Planck equation with prescribed constant
coefficients of diffusion and linear friction describes the ensemble average of
the stochastic evolutions in velocity space of a Brownian test particle
immersed in a heat bath of fixed temperature. Apparently, it is not so well
known that the same partial differential equation, but now with constant
coefficients which are functionals of the solution itself rather than being
prescribed, describes the kinetic evolution (in the infinite particle limit) of
an isolated N-particle system with certain stochastic interactions. Here we
discuss in detail this recently discovered interpretation.Comment: Minor revisions and corrections (including the title
X-ray photoelectron spectroscopy studies of non-stoichiometric superconducting NbB2+x
Polycrystalline samples of NbB2+x with nominal composition (B/Nb) = 2.0, 2.1,
2.2, 2.3, 2.4 and 2.5 were studied by X-ray photoelectron spectroscopy (XPS).
The spectra revealed Nb and B oxides on the surface of the samples, mainly B2O3
and Nb2O5. After Ar ion etching the intensity of Nb and B oxides decreased. The
Nb 3d5/2 and B 1s core levels associated with the chemical states (B/Nb) were
identified and they do not change with etching time. The Binding Energy of the
Nb 3d5/2 and B 1s core levels increase as boron content increases, suggesting a
positive chemical shift in the core levels. On the other hand, analysis of
Valence Band spectra showed that the contribution of the Nb 4d states slightly
decreased while the contribution of the B 2p(pi) states increased as the boron
content increased. As a consequence, the electronic and superconducting
properties were substantially modified, in good agreement with band-structure
calculations.Comment: 10 pages, 7 figures, 1 tabl
The Vlasov continuum limit for the classical microcanonical ensemble
For classical Hamiltonian N-body systems with mildly regular pair interaction
potential it is shown that when N tends to infinity in a fixed bounded domain,
with energy E scaling quadratically in N proportional to e, then Boltzmann's
ergodic ensemble entropy S(N,E) has the asymptotic expansion S(N,E) = - N log N
+ s(e) N + o(N); here, the N log N term is combinatorial in origin and
independent of the rescaled Hamiltonian while s(e) is the system-specific
Boltzmann entropy per particle, i.e. -s(e) is the minimum of Boltzmann's
H-function for a perfect gas of "energy" e subjected to a combination of
externally and self-generated fields. It is also shown that any limit point of
the n-point marginal ensemble measures is a linear convex superposition of
n-fold products of the H-function-minimizing one-point functions. The proofs
are direct, in the sense that (a) the map E to S(E) is studied rather than its
inverse S to E(S); (b) no regularization of the microcanonical measure
Dirac(E-H) is invoked, and (c) no detour via the canonical ensemble. The proofs
hold irrespective of whether microcanonical and canonical ensembles are
equivalent or not.Comment: Final version; a few typos corrected; minor changes in the
presentatio
Virial theorem for rotating self-gravitating Brownian particles and two-dimensional point vortices
We derive the proper form of Virial theorem for a system of rotating
self-gravitating Brownian particles. We show that, in the two-dimensional case,
it takes a very simple form that can be used to obtain general results about
the dynamics of the system without being required to solve the
Smoluchowski-Poisson system explicitly. We also develop the analogy between
self-gravitating systems and two-dimensional point vortices and derive a
Virial-like relation for the vortex system
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