Dark solitary waves in the nonlinear Schrödinger equation with third order dispersion, self-steepening, and self-frequency shift.

We solve the higher order nonlinear Schrödinger equation describing the propagation of ultrashort pulses in optical fibers. By means of the coupled amplitude-phase formulation fundamental (solitary wave) dark soliton solutions are found.

Equivalent-optical-waveguide model for the analysis of optical waveguides by means of an asymptotic effective-index method.

We present a theoretical method that makes it possible to analyze three-dimensional (3-D) integrated optical waveguides with arbitrary refractive-index profiles. With this method it is easy to obtain effective indexes, propagation constants, and coupling-switching properties of planar and channel optical waveguides. This theoretical approach involves one's modeling the original optical waveguide by means of an equivalent optical waveguide whose effective index is evaluated by the application of a technique that we call the asymptotic effective-index method. The numerical values show good convergence and accuracy for effective indexes, propagation constants, and coupling-switching characteristics. Theoretical and experimental results are given.

The axio-somatic model in embryonic and tumoral development.

The growth and evolution of human tissues observed in embryogenesis and neoplasia are both reduced to a cellular theoretical axio-somatic model. The unlimited expansion and phenotype change of the model, are assured by the continuous generation of new cellular mitotic phenotypes which are grafted in a sequential order. Neogeneration results from the interaction between two cells of specific origins and situations: (a) axial cells of actual germ cell origin, generators and vectors of mitotic potential, (b) mitotically exhausted somatic cells of distal phenotypes, involved in meiotic recombinations, generating potential of neodifferentiation. The potentialities of both, axis and soma, are transformed by 'fertilization' in effectively growing new mitotic phenotypes. Bi-potent differentiation of germ line derived cells in gametopoiesis and haematopoiesis, is the source of the axial phenotype, identified in tissues as specific acid fast 'lymphoid' cells and/or vectors, formed by highly condensed hyperchromatinic nuclei and/or micronuclei endowed with DNAs of centromeric and kinetochoric types, wrapped in ceramide rich photo-affinity biomembranes.

Verification of generalized telegraphist's equations applied to dielectric waveguide problems: comment.

In accordance with the paper by So and Lee [Appl. Opt. 31, 6446-6452 (1992)], the efficiency of the Schelkunoff's method as applied to dielectric waveguide problems needs to be clarified. Previous papers have demonstrated the accuracy of the generalized telegraphist's equations in electromagnetic modal analysis on shielded dielectric waveguides as well as their application to electromagnetic-scattering properties. The basic mode-selection process can be clearly improved to get sharp reductions in CPU times and to assure very good solutions of slow, fast, evanescent, and complex waves. As a consequence, to analyze passive devices on dielectric waveguides, the cascaded set of multiple discontinuities model can be used. The modal matching technique has been used to demonstrate this possibility in calculating the generalized scattering matrix. Furthermore, the resulting electromagnetic field in a shielded dielectric waveguide structure can be used to calculate the cross-section dimensions of the metallic walls to simulate the dielectric configuration as in the open air.