Miniaturized highly brilliant diode laser modules for future display applications

We demonstrate diode laser modules with high spectral radiance larger than 1 GW/cm²/sr/nm in the visible spectral range. These highly brilliant laser light sources enable the development of next-generation 3D displays. About 1W output power from small-sized modules was achieved at 635 nm by direct diode laser emission and at 530 nm using single pass second harmonic generation (SHG) of a highly brilliant near-infrared laser diode.     

Bose-einstein correlations of soft pions in ultrarelativistic nucleus-nucleus collisions

A detailed analysis of pair correlations of positive pions in the target fragmentation region is presented. Data on nuclear collisions at 200 GeV per nucleon were measured with the Plastic Ball in the WA80 experiment at the CERN SPS. The correlation functions are compared with analytical functions and with simulations incorporating Bose-Einstein symmetrization, final-state interactions and detector resolution. Source radii are shown to increase with increasing target size and with centrality. For central collisions the radii are larger than the geometrical sizes of the involved nuclei.     

An overview of lexicographic choice under uncertainty

This overview focuses on lexicographic choice under conditions of uncertainty. First, lexicographic versions of traditional (von Neumann-Morgenstern) expected utility theory are described where the usual Archimedean axiom is weakened. The role of these lexicographic variants in explaining some well-known paradoxes of choice theory is reviewed. Next, the significance of lexicographic choice for game theory is discussed. Finally, some lexicographic extensions of the classical maximin decision rule are described.The authors wish to acknowledge financial support from NSF Grant IRI-8608964, Harvard Business School Division of Research, and the Miller Institute for Basic Research in Science. We are grateful to Irving LaValle and Peter Fishburn for encouragement and helpful comments.     

Permeability of polymer materials to compounds containing radionuclides

The permeability of rubber and PE gloves, PE bags and strippable PVC paint to HTO, Na¹²⁵I, H₂ ³⁵SO₄, H₃ ³²PO₄,¹⁴¹CeCl₃,⁸⁹SrCl₂, and,¹³⁷CsCl in aqueous solution was tested. All materials were permeable to HTO and Na¹²⁵I. Whereas rubber gloves were permeable the other materials were impermeable to H₂ ³⁵SO₄. The remaining radioactive compounds showed no penetration. The diffusion coefficients of the penetrating compounds were calculated on the basis of Fick's First Law for the respective materials. The permeability to Na¹²⁵I and HTO decreases in the order rubber, PVC paint, and PE. Penetration increases in the order H₂ ³⁵SO₄, Na¹²⁵I, and HTO.     

The demicellization of alkyltrimethylammonium bromides in 0.1 M sodium chloride solution studied by isothermal titration calorimetry

The demicellization of the cationic detergents dodecyltrimethylammonium bromide, tetradecyltrimetylammonium bromide, and cetyltrimethylammonium bromide was studied at temperatures between 20 and 60 degrees C in 0.1 M NaCl (pH 6.4) using isothermal titration calorimetry (ITC). We determined the critical micellization concentration (cmc) of the cationic detergents which show a minimum at temperatures between 20 and 34 degrees C. In accordance with the lengthening of the hydrophobic tail of the detergents the cmc decreases with increasing alkyl chain length. The thermodynamic parameters describing the changes of enthalpy (DeltaH(demic)), the changes of entropy (DeltaS(demic)) and the Gibbs free energy change (DeltaG(demic)) for demicellization were first obtained using the pseudophase-separation model. The aggregation number n at the cmc as well as the demicellization enthalpy, entropy and Gibbs free energy change were also calculated using a simulation based on the mass-action model. Furthermore, we investigated the demicellization of CTAB in deionized water in comparison to demicellization in sodium chloride solution to determine the influence of counter ion binding on the demicellization.     

Diffusion through rubbery and glassy polymer membranes

Mass transport of a number of organic vapors through polydimethylsiloxane films (PDMS) and carbon dioxide through a variety of polyimides based on a hexafluorotetracarboxylic acid unit (6FDA) were investigated. Vapor diffusion through PDMS films strongly depends on the concentration of the penetrant molecules in the network. For chloroform, increasing diffusivity at lower upstream activities occurs due to network plasticization, while a decreasing diffusion coefficient at larger concentration is supposed to stem from penetrant molecule clustering. The diffusion of carbon dioxide in 6FDA-based polyimides was modelled on a molecular basis. An exponential relation was found between Δc_p and the diffusion coefficient and the permeability, respectively. This relation holds also for on-chain modifications.