Detection thresholds for gaps, overlaps, and no-gap-no-overlaps

Detection thresholds for gaps and overlaps, that is acoustic and perceived silences and stretches of overlapping speech in speaker changes, were determined. Subliminal gaps and overlaps were categorized as no-gap-no-overlaps. The established gap and overlap detection thresholds both corresponded to the duration of a long vowel, or about 120 ms. These detection thresholds are valuable for mapping the perceptual speaker change categories gaps, overlaps, and no-gap-no-overlaps into the acoustic domain. Furthermore, the detection thresholds allow generation and understanding of gaps, overlaps, and no-gap-no-overlaps in human-like spoken dialogue systems.     

Liquid Chromatographic Analysis of Various Formulations Containing Emtricitabine

A gradient liquid chromatographic (LC) method for control of emtricitabine (FTC) was validated for the analysis of FTC formulations (capsules and oral solution) and fixed-dose-combination tablets containing FTC [FTC combined with tenofovir disoproxil fumarate (TDF) and FTC combined with TDF and efavirenz (EFV)]. The method is based on the purity test recently prescribed in the International Pharmacopoeia and uses a Hypersil BDS C18 column (25 cm × 4.6 mm i.d.), 5 μm kept at a temperature of 35 °C. Other reversed-phase columns were also investigated. The mobile phases for gradient elution consist of acetonitrile, phosphate buffer and water. The flow rate is 1.0 mL min^?1 and UV detection is performed at 280 nm. The method is capable of separating the main components from one another, from the inactive ingredients and from the main degradation products. The method was validated with respect to accuracy, precision, sensitivity and linearity for each component and the solution media were optimized. Finally, commercial FTC capsules, FTC oral solution, FTC/TDF tablets and FTC/TDF/EFV tablets were examined.     

Enantioselective transesterification of a tertiary alcohol by lipase A from Candida antarctica

Chiral tertiary alcohols and their esters represent important flavor compounds and are useful building blocks. Unfortunately, they are accepted by only a few lipases/esterases as substrates and enantioselectivity is usually very low. We report here a highly enantioselective transesterification of the tertiary alcohol 2-phenylbut-3-yn-2-ol using lipase A from Candida antarctica (CAL-A). Under optimized conditions, the corresponding acetate was obtained with 94%ee at 35% conversion equivalent to an enantioselectivity factor of E=65. In contrast, enantioselective hydrolysis of the racemic acetate was not feasible as this is very prone to autohydrolysis.     

Geometric obstruction of black holes

We study the global structure of Lorentzian manifolds with partial sectional curvature bounds. In particular, we prove completeness theorems for homogeneous and isotropic cosmologies as well as static spherically symmetric spacetimes. The completeness of the latter is then employed to rigorously prove the absence of static spherically symmetric black holes in more than three dimensions. The proof of these new results is preceded by a pedagogic review of the local aspects of sectional curvature bounds for Lorentzian manifolds, which extends and strengthens previous constructions.     

Combination of schlieren and pulsed TV holography in the study of a high-speed flame jet

This paper presents studies of the propagation of a high-speed turbulent flame jet of an air/hydrogen gas mixture. The experimental results are recorded with the schlieren and the pulsed TV holography method. These methods are compared and combined to benefit from the advantages of each of them. Abel inversion has been used to achieve three-dimensional information i.e. refractive index distributions. Evaluation, calibration and Abel inversion algorithms are described together with experimental results. The results obtained from the different techniques show remarkable similarities concerning both qualitative and quantitative aspects.