On the Caudrey-Beals-Coifman System and the Gauge Group Action

The generalized Zakharov-Shabat systems with complex-valued Cartan elements and the systems studied by Caudrey, Beals and Coifman (CBC systems) and their gauge equivalent are studies. This includes: the properties of fundamental analytical solutions (FAS) for the gauge-equivalent to CBC systems and the minimal set of scattering data; the description of the class of nonlinear evolutionary equations solvable by the inverse scattering method and the recursion operator, related to such systems; the hierarchies of Hamiltonian structures.Comment: 12 pages, no figures, contribution to the NEEDS 2007 proceedings (Submitted to J. Nonlin. Math. Phys.

N-wave interactions related to simple Lie algebras. Z_2- reductions and soliton solutions

The reductions of the integrable N-wave type equations solvable by the inverse scattering method with the generalized Zakharov-Shabat systems L and related to some simple Lie algebra g are analyzed. The Zakharov- Shabat dressing method is extended to the case when g is an orthogonal algebra. Several types of one soliton solutions of the corresponding N- wave equations and their reductions are studied. We show that to each soliton solution one can relate a (semi-)simple subalgebra of g. We illustrate our results by 4-wave equations related to so(5) which find applications in Stockes-anti-Stockes wave generation.Comment: 18 pages, 1 figure, LaTeX 2e, IOP-style; More clear exposition. Introduction and Section 5 revised. Some typos are correcte

Blinding Authority: Randomized Clinical Trials and the Production of Global Scientific Knowledge in Contemporary Sri Lanka

In this article, the authors present an ethnography of biomedical knowledge production and science collaboration when they take place in developing country contexts. The authors focus on the arrival of international clinical trials to Sri Lanka and provide analysis of what was described as one of the first multisited trials in the country, a pharmaceutical company sponsored, phase 2, randomized, double-blind, placebo controlled trial carried out between 2009 and 2010. Using interviews with those who conducted the trial and six months of participant observation at the trial hospital, the authors describe the work that goes on to perform trials according to international standards. The article describes what happens when a randomized controlled trial encounters existing epistemic virtues and documents the impacts on ideas of authority, expertise and doctor–patient relationships found in Sri Lankan medicine