The United Shoe Machinery Company dominated world market for footwear machinery in the first half of the twentieth century. This article analyzes the company's strategy, its penetration in Latin America and the rest of the world, and the impact on the company of antitrust lawsuits in the United States. Despite its practical monopoly, the company had an efficient performance, which fueled technological innovation and modernization of footwear industry in many countries.

Este artículo analiza la estrategia de la United Shoe Machinery Company, empresa que dominó el mercado mundial de maquinaria para calzado en la primera mitad del siglo XX, su penetración en Latinoamérica y en el resto del mundo y los procesos judiciales antimonopolio que sufrió en Estados Unidos. A pesar de su posición de práctico monopolio, la empresa tuvo un desempeño eficiente que impulsó la innovación tecnológica y la modernización de la industria del calzado en muchos países.

We investigate the flow of two immiscible, viscous fluids in the confined geometry of a Hele-Shaw cell. We consider that one of the fluids is a ferrofluid and that an external magnetic field is applied. The interfacial instabilities which arise between the fluids are studied for various situations: (a) different cell geometries (radial, rectangular); (b) frontal and parallel flows; (c) distinct applied field configurations (tangential, perpendicular, normal) and (d) motionless and rotating cells. The interplay between applied magnetic field and several other destabilizing/stabilizing factors in determining the interface behavior is analyzed. Stability analysis and numerical simulations are used to describe linear and nonlinear stages of the interface evolution.