3,238 research outputs found
Evaluation of commercial GaN HEMTs for pulsed power applications
A non-conformally invariant coupling between the inflaton and the photon in the minimal Lorentz-violating standard model extension is analyzed. For specific forms of the Lorentz-violating background tensor, the strong-coupling and back-reaction problems of magnetogenesis in de Sitter inflation with scale are evaded, the electromagnetic-induced primordial spectra of (Gaussian and non-Gaussian) scalar and tensor curvature perturbations are compatible with cosmic microwave background observations, and the inflation-produced magnetic field directly accounts for cosmic magnetic fields
New Solutions of the T-Matrix Theory of the Attractive Hubbard Model
This short paper summarizes a calculational method for obtaining the
dynamical properties of many-body theories formulated in terms of
(unrenormalized) bare propagators (and more generally, in terms of meromorphic
functions, or convolutions over meromorphic functions) to a very high accuracy.
We demonstrate the method by applying it to a T-matrix theory of the attractive
Hubbard model in two dimensions. We expand the pair propagator using a partial
fraction decomposition, and then solve for the residues and pole locations of
such a decomposition using a computer algebra system to an arbitrarily high
accuracy (we used MapleV and obtained these quantities to a relative error of
10^(-80)). Thus, this method allows us to bypass all inaccuracies associated
with the traditional analytical continuation problem. Our results for the
density of states make clear the pronounced development of a pseudogap as the
temperature is lowered in this formulation of the attractive Hubbard model.Comment: 2 pages, 2 figure
Une théorie réaliste des prix et de la production
The assumption of a single price at any time is very generally imposed on market theorizing. It is unrealistic, but generally accepted because of the needs of welfare theory, and of current theoretical methods. In order to evaluate the significance of the loss in realism from the use of this assumption, it seems to be worthwhile to start with the other extreme of complete ignorance in a market, and allow buyers and sellers to pair off at random, allowing a diversity of prices. It is very interesting that in such a "blind market" the quantity traded tends to be larger, by about 44 per cent.The theory of such a market can be based on a Marshallian industry, and many different versions are suggested. The theory does seem to give useful insight into the results of imposing uniform pricing by barbers, and uniform wage rates in labour markets. The loss in trade and employment seems to be great enough that we should examine a little more carefully the arguments that have been accepted so easily that such uniformity implies greater equity
Technological unemployment – A Failure in Theorizing
The subject of technological unemployment is used to illustrate how accepted theory leads to wrong answers because the technique used is that of partial equilibrium analysis. On this basis one rules out the investment needed to make the change in production method. In a dynamic context, in which such change continues, the employment effects of this investment should be allowed, and they can be seen to be substantial relative to the loss in employment from the installation of the new capital equipment. The result is that technological change conceived in this broad context is expansionary, and the implications for industrial relations and other policies is very important
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