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Word of mouth (WOM) affects diffusion and sales, but why are certain products talked about more than others, both right after consumers first experience them and in the months that follow? This article examines psychological drivers of immediate and ongoing WOM. The authors analyze a unique data set of everyday conversations for more than 300 products and conduct both a large field experiment across various cities and a controlled laboratory experiment with real conversations. The results indicate that more interesting products get more immediate WOM but, contrary to intuition, do not receive more ongoing WOM over multiple months or overall. In contrast, products that are cued more by the environment or are more publicly visible receive more WOM both right away and over time. Additional analyses demonstrate which promotional giveaways in WOM marketing campaigns are associated with increased WOM. overall, the findings shed light on psychological drivers of WOM and provide insight into designing more effective WOM campaigns.

The real time changes occurring within films of cylinder-forming poly(α-methylstyrene-block-4-hydroxystyrene) (PαMS-b-PHOST) were monitored as they were swollen in tetrahydrofuran (THF) and acetone solvent vapors. In situ information was obtained by combining grazing incidence small angle X-ray scattering (GISAXS) with film thickness monitoring of the solvent vapor swollen films. We show that for self assembly to occur, the polymer thin film must surpass a swollen thickness ratio of 212% of its original thickness when swollen in THF vapors and a ratio of 268% for acetone vapor annealing. As the polymer becomes plasticized by solvent vapor uptake, the polymer chains must become sufficiently mobile to self assemble, or reorganize, at room temperature. Using vapors of a solvent selective to one of the blocks, in our case PHOSTselective acetone, an order-order transition occured driven by the shift in volume fraction. The BCC spherical phase assumed in the highly swollen state can be quenched by rapid drying. Upon treatment with vapor of a non-selective solvent, THF, the film maintained the cylindrical morphology suggested by its dry-state volume fraction. In situ studies indicate that self-assembly occurs spontaneously upon attaining the threshold swelling ratios.

Poly(alpha-methylstyrene)-block-poly(4-hydroxystyrene) acts as both a lithographic deep UV photoresist and a self-assembling material, making it ideal for patterning simultaneously by both top-down and bottom-up fabrication methods. Solvent vapor annealing improves the quality of the self-assembled patterns in this material without compromising its ability to function as a photoresist. The choice of solvent used for annealing allows for control of the self-assembled pattern morphology. Annealing in a nonselective solvent (tetrahydrofuran) results in parallel orientation of cylindrical domains, while a selective solvent (acetone) leads to formation of a trapped spherical morphology. Finally, we have self-assembled both cylindrical and spherical phases within lithographically patterned features, demonstrating the ability to precisely control ordering. Observing the time evolution of switching from cylindrical to spherical morphology within these features provides clues to the mechanism of ordering by selective solvent.

Abstract-This study focuses on the development of a nonlinear control design for a fully-actuated autonomous underwater vehicle (AUV) using a continuous robust integral of the sign of the error control structure to compensate for system uncertainties and sufficiently smooth bounded exogenous disturbances. A Lyapunov stability analysis is included to prove semiglobal asymptotic tracking. The resulting controller is experimentally validated on an AUV developed at the University of Florida in both controlled and open-water environments.Index Terms-Autonomous underwater vehicles (AUVs), marine robotics, nonlinear control, robust integral of the sign of the error (RISE).