The Similarity Degree of Some C*-algebras

We define the class of weakly approximately divisible unital C*-algebras and show that this class is closed under direct sums, direct limits, any tensor product with any C*-algebra, and quotients. A nuclear C*-algebra is weakly approximately divisible if and only if it has no finite-dimensional representations. We also show that Pisier's similarity degree of a weakly approximately divisible C*-algebra is at most 5

MF-traces and a Lower Bound for the Topological Free Entropy Dimension in Unital C*-algebras

We continue previous work on Voiculescu's topological free entropy dimension {\delta}_{top}. We introduce the notions of MF-trace, MF-ideal, and MF-nuclearity and use these concepts to obtain upper and lower bounds for {\delta}_{top}, and in many cases we obtain an exact formula for {\delta}_{top}. We also discuss semicontinuity properties of {\delta}_{top}

Buoyancy-driven motion of bubbles in the presence of soluble surfactants

We present our experimental results for the effect of bulk-soluble surfactants on the buoyancy-driven motion of an air bubble rising in circular, square and rectangular channels filled with a liquid. The bulk fluid is either Newtonian or viscoelastic with or without surfactants. In a Newtonian fluid, small bubbles are nearly spherical travelling with a velocity much lower than the Hadamard-Rybczinski velocity. Long bubbles were prolate translating with a velocity independent of the bubble size. Cusps form in all the viscoelastic systems studied. Even in the presence of small amounts of surfactants bubble shapes were elongated and mobility is reduced due to Marangoni effects. At surfactant concentrations above CMC small bubbles are partially remobilized while long bubbles are completely remobilized. The effect of the channel geometry on bubble mobility and deformation are also presented