Phase Separation of Rigid-Rod Suspensions in Shear Flow

We analyze the behavior of a suspension of rigid rod-like particles in shear flow using a modified version of the Doi model, and construct diagrams for phase coexistence under conditions of constant imposed stress and constant imposed strain rate, among paranematic, flow-aligning nematic, and log-rolling nematic states. We calculate the effective constitutive relations that would be measured through the regime of phase separation into shear bands. We calculate phase coexistence by examining the stability of interfacial steady states and find a wide range of possible ``phase'' behaviors.Comment: 23 pages 19 figures, revised version to be published in Physical Review

Success and Risk Factors in the Pre-Startup Phase

Why does one person actually succeed in starting a business, while a second person gives up? In order to answer this question, a sample of 517 nascent entrepreneurs (people in the process of setting up a business) was followed over a 3-year period. After this period, it was established that 195 efforts were successful and that 115 start up efforts were abandoned. Our research focuses on estimating the relative importance of a variety of approaches and variables in explaining pre-start-up success. These influences are organized in terms of Gartner’s (1985) framework of new venture creation. This framework suggests that start-up efforts differ in terms of the characteristics of the individual(s) who start the venture, the organization that they create, the environment surrounding the new venture, and the process by which the new venture is started. Logistic regression analyses are run for the sample as a whole as well as for subgroups within the sample, namely for those with high ambition versus low ambition and for those with substantial versus limited experience. The results point to the importance of perceived risk of the market as a predictor of getting started versus abandoning the start up effort. Copyright Springer 2006performance, survival, nascent entrepreneurs, start-ups, M13,