13,167 research outputs found
An investigation of S-band signal transmission through an Apollo earth-entry plasma
Investigation of S band signal transmission through Apollo earth entry plasm
Symmetry of the Schr\"odinger equation with variable potential
We study symmetry properties of the Schr\"odinger equation with the potential
as a new dependent variable, i.e., the transformations which do not change the
form of the class of equations. We also consider systems of the Schr\"odinger
equations with certain conditions on the potential. In addition we investigate
symmetry properties of the equation with convection term. The contact
transformations of the Schr\"odinger equation with potential are obtained
The Sasaki Join, Hamiltonian 2-forms, and Sasaki-Einstein Metrics
By combining the join construction from Sasakian geometry with the
Hamiltonian 2-form construction from K\"ahler geometry, we recover
Sasaki-Einstein metrics discovered by physicists. Our geometrical approach
allows us to give an algorithm for computing the topology of these
Sasaki-Einstein manifolds. In particular, we explicitly compute the cohomology
rings for several cases of interest and give a formula for homotopy equivalence
in one particular 7-dimensional case. We also show that our construction gives
at least a two dimensional cone of both Sasaki-Ricci solitons and extremal
Sasaki metrics.Comment: 38 pages, paragraph added to introduction and Proposition 4.1 added,
Proposition 4.15 corrected, Remark 5.5 added, and explanation for irregular
Sasaki-Einstein structures expanded. Reference adde
The Sasaki Join, Hamiltonian 2-forms, and Constant Scalar Curvature
We describe a general procedure for constructing new Sasaki metrics of
constant scalar curvature from old ones. Explicitly, we begin with a regular
Sasaki metric of constant scalar curvature on a 2n+1-dimensional compact
manifold M and construct a sequence, depending on four integer parameters, of
rays of constant scalar curvature (CSC) Sasaki metrics on a compact Sasaki
manifold of dimension . We also give examples which show that the CSC
rays are often not unique on a fixed strictly pseudoconvex CR manifold or a
fixed contact manifold. Moreover, it is shown that when the first Chern class
of the contact bundle vanishes, there is a two dimensional subcone of Sasaki
Ricci solitons in the Sasaki cone, and a unique Sasaki-Einstein metric in each
of the two dimensional sub cones.Comment: 32 pages. A gap in the argument of applying the admissibility
conditions to irregular Sasakian structures is filled. Some minor corrections
and additions are also made. This is the final version which will appear in
the Journal of Geometric Analysis. It also encorporates much from our paper
arXiv:1309.706
Some Heuristic Semiclassical Derivations of the Planck Length, the Hawking Effect and the Unruh Effect
The formulae for Planck length, Hawking temperature and Unruh-Davies
temperature are derived by using only laws of classical physics together with
the Heisenberg principle. Besides, it is shown how the Hawking relation can be
deduced from the Unruh relation by means of the principle of equivalence; the
deep link between Hawking effect and Unruh effect is in this way clarified.Comment: LaTex file, 6 pages, no figure
An ultra-low frequency electromagnetic wave force mechanism for the ionosphere
Ultra-low frequency electromagnetic wave force mechanism for ionospheric anomalie
The Paradoxical Forces for the Classical Electromagnetic Lag Associated with the Aharonov-Bohm Phase Shift
The classical electromagnetic lag assocated with the Aharonov-Bohm phase
shift is obtained by using a Darwin-Lagrangian analysis similar to that given
by Coleman and Van Vleck to identify the puzzling forces of the Shockley-James
paradox. The classical forces cause changes in particle velocities and so
produce a relative lag leading to the same phase shift as predicted by Aharonov
and Bohm and observed in experiments. An experiment is proposed to test for
this lag aspect implied by the classical analysis but not present in the
currently-accepted quantum topological description of the phase shift.Comment: 8 pages, 3 figure
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