Higher conservation laws for coherent optical pulse propagation in an inhomogeneously broadened medium.
The description of coherent optical pulse propagation in terms of coupled Maxwell and Schroedinger- Bloch equations in slowly varying envelope approximation possesses conservation laws in addition to those of field energy and field momentum. Comparison with preliminary numerical results has shown that these higher conservation laws can be used to predict the amplitude of each of the 2pi pulses into which an intense coherent pulse may decompose as it propagates through an attenuator. In the present paper a comparison with more extensive numerical results is carried out. It is shown that over a wide range of variation of the parameters involved the conservation laws yield results in agreement with those obtained through numerical computation.
Excitation spectrum of the one-dimensional Fermi gas with backward scattering
The energy spectrum of the one-dimensional electron gas, solved by Luther and Emery for a particular attractive interaction strength $U$ of the backward scattering across the Fermi surface, has been calculated for small deviations from this particular limit. The energy spectrum shows a gap at the Fermi energy, whose magnitude is very sensitive to the interaction $U$. The density of states shows a gap at zero temperature, which is smeared out by the quasiparticle lifetime for $T\ensuremath{\ne}0$.
How Does the Keyword Method Affect Vocabulary Comprehension and Usage? Report from the project on Studies in Language: Reading and Communication. Working Paper No. 278.
THE KEYWORD METHOD of vocabulary learning involves forming a linkage between a to-be-learned vocabulary word and a familiar English word that sounds like part of the to-be-learned item (the keyword). Then the learner forms an interactive image between the keyword and definition referents. In previous research, the keyword method has been found to facilitate students' recall of definitions, given vocabulary items. In this study, use of the method was also shown to increase comprehension of English vocabulary in context, as well as usage of that vocabulary in a novel context.