2,558 research outputs found
Magnetic forming studies
Investigation of the tensile strength dependability on the characteristic time over which a pressure pulse is applied to a metal workpiece shows that the mechanical properties of these materials are functions of the rate at which the material is undergoing strain. These results and techniques are used in magnetomotive metal forming
Inversion of Gamow's Formula and Inverse Scattering
We present a pedagogical description of the inversion of Gamow's tunnelling
formula and we compare it with the corresponding classical problem. We also
discuss the issue of uniqueness in the solution and the result is compared with
that obtained by the method of Gel'fand and Levitan. We hope that the article
will be a valuable source to students who have studied classical mechanics and
have some familiarity with quantum mechanics.Comment: LaTeX, 6 figurs in eps format. New abstract; notation in last
equation has been correcte
A New Kind of Finance
Finance has benefited from the Wolfram's NKS approach but it can and will
benefit even more in the future, and the gains from the influence may actually
be concentrated among practitioners who unintentionally employ those principles
as a group.Comment: 13 pages; Forthcoming in "Irreducibility and Computational
Equivalence: 10 Years After Wolfram's A New Kind of Science," Hector Zenil,
ed., Springer Verlag, 201
Perfectly Translating Lattices on a Cylinder
We perform molecular dynamics simulations on an interacting electron gas
confined to a cylindrical surface and subject to a radial magnetic field and
the field of the positive background. In order to study the system at lowest
energy states that still carry a current, initial configurations are obtained
by a special quenching procedure. We observe the formation of a steady state in
which the entire electron-lattice cycles with a common uniform velocity.
Certain runs show an intermediate instability leading to lattice
rearrangements. A Hall resistance can be defined and depends linearly on the
magnetic field with an anomalous coefficient reflecting the manybody
contributions peculiar to two dimensions.Comment: 13 pages, 5 figure
Interior Weyl-type Solutions of the Einstein-Maxwell Field Equations
Static solutions of the electro-gravitational field equations exhibiting a
functional relationship between the electric and gravitational potentials are
studied. General results for these metrics are presented which extend previous
work of Majumdar. In particular, it is shown that for any solution of the field
equations exhibiting such a Weyl-type relationship, there exists a relationship
between the matter density, the electric field density and the charge density.
It is also found that the Majumdar condition can hold for a bounded perfect
fluid only if the matter pressure vanishes (that is, charged dust). By
restricting to spherically symmetric distributions of charged matter, a number
of exact solutions are presented in closed form which generalise the
Schwarzschild interior solution. Some of these solutions exhibit functional
relations between the electric and gravitational potentials different to the
quadratic one of Weyl. All the non-dust solutions are well-behaved and, by
matching them to the Reissner-Nordstr\"{o}m solution, all of the constants of
integration are identified in terms of the total mass, total charge and radius
of the source. This is done in detail for a number of specific examples. These
are also shown to satisfy the weak and strong energy conditions and many other
regularity and energy conditions that may be required of any physically
reasonable matter distribution.Comment: 21 pages, RevTex, to appear in General Relativity and Gravitatio
Optical Dispersion In Annealed Thin Films of S-doped a-Si:H Alloys
S-doped amorphous hydrogenated silicon (a-Si,S:H) thin films were prepared by conventional PECVD method on corning glass substrates. The prepared thin films were subsequently annealed in vacuum (~ 2 × 10 – 6 Torr) in the temperature range from 100 °C to 500 °C. The annealing effects at room temperature were examined by means of optical transmission spectra of the films in the wavelength range 300-1100 nm. Dispersion in optical constants such as transmittance, bandgap and refractive index were observed. Tailoring in optical constants was observed with respect to doping concentrations as well as the annealing temperatures.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3097
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Right heart failure: toward a common language
Abstract In this guideline, the International Right Heart Foundation Working Group moves a step forward to develop a common language to describe the development and defects that exemplify the common syndrome of right heart failure. We first propose fundamental definitions of the distinctive components of the right heart circulation and provide consensus on a universal definition of right heart failure. These definitions will form the foundation for describing a uniform nomenclature for right heart circulatory failure with a view to foster collaborative research initiatives and conjoint education in an effort to provide insight into mechanisms of disease unique to the right heart
The Tolman VII solution, trapped null orbits and w - modes
The Tolman VII solution is an exact static spherically symmetric perfect
fluid solution of Einstein's equations that exhibits a surprisingly good
approximation to a neutron star. We show that this solution exhibits trapped
null orbits in a causal region even for a tenuity (total radius to mass ratio)
. In this region the dynamical part of the potential for axial w - modes
dominates over the centrifugal part.Comment: 5 pages revtex. 10 figures png. Further information at
http://grtensor.phy.queensu.ca/tolmanvii
The importance of quantum decoherence in brain processes
Based on a calculation of neural decoherence rates, we argue that that the
degrees of freedom of the human brain that relate to cognitive processes should
be thought of as a classical rather than quantum system, i.e., that there is
nothing fundamentally wrong with the current classical approach to neural
network simulations. We find that the decoherence timescales ~10^{-13}-10^{-20}
seconds are typically much shorter than the relevant dynamical timescales
(~0.001-0.1 seconds), both for regular neuron firing and for kink-like
polarization excitations in microtubules. This conclusion disagrees with
suggestions by Penrose and others that the brain acts as a quantum computer,
and that quantum coherence is related to consciousness in a fundamental way.Comment: Minor changes to match accepted PRE version. 15 pages with 5 figs
included. Color figures and links at
http://www.physics.upenn.edu/~max/brain.html or from [email protected].
Physical Review E, in pres
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