Tuning Nonlinear Mechanical Mode Coupling in GaAs Nanowires Using Cross-Section Morphology Control.

We investigate the nonlinear mechanical properties of GaAs nanowires with anisotropic cross-section. Fundamental and second order flexural modes are studied using laser interferometry with good agreement found between experiment and theory describing the nonlinear response under mechanical excitation. In particular, we demonstrate that the sign of the nonlinear coupling between orthogonal modes is dependent on the cross-section aspect ratio. The findings are of interest for applications such as amplitude to frequency conversion and vectorial force sensing

Relation between distress risk, book‐to‐market ratio and return premium

Purpose – Earlier research found that firms with the highest distress risk have low book-to-market (B/M) ratios and low returns. This paper aims to examine the robustness of those's results and provide further evidence that high distress-risk firms do not enjoy the same high returns earned by high B/M firms and that distress risk is unlikely to explain the Fama and French high-minus-low (HML) B/M factor. Design/methodology/approach – A distress-risk measure, distressed-minus-solvent (DMS), is calculated and a range of zero investment distress-risk trading strategies is investigated. Value- and equal-weighted portfolios are examined both with negative book-equity firms and without. These most distressed firms have low or negative B/M values and would either not be included in the Fama and French sample or included in the low B/M portfolio. Findings – The paper finds that the DMS factor is negative and significant, and none of the zero investment strategies earns significantly positive returns. Research limitations/implications – The findings suggest that exposure to distress risk does not earns investors a positive risk premium. It appears that over the period examined, market inefficiencies drive the market value and returns of high distress-risk firms. Originality/value – The distress-risk premium is shown to be negative and, therefore, cannot be driven by bankruptcy risk alone. The negative premium is not consistent with a financial distress explanation for the Fama and French HML factor

Haemophilus ducreyi Lipooligosaccharide Mutant Defective in Expression of β-1,4-Glucosyltransferase Is Virulent in Humans

The lipooligosaccharide (LOS) of Haemophilus ducreyi contains a major glycoform that is immunochemically identical to paragloboside, a glycosphingolipid precursor of major human blood group antigens. We recently identified the gene responsible for the glucosyltransferase activity and constructed an isogenic mutant (35000glu-) deficient in this activity. 35000glu- makes an LOS that consists only of the heptose trisaccharide core and 2-keto-deoxyoctulosonic acid (KDO). For this study, the mutant was reconstructed in the 35000HP (human passaged [HP]) background. Five human subjects were inoculated with 35000HP and 35000HPglu- in a dose-response trial. The pustule formation rates were 40% (95% confidence interval [CI], 13.7 to 72.6%) at 10 sites for 35000HP and 46.7% (95% CI, 24.8 to 69.9%) at 15 sites for 35000HPglu-. The histopathology and recovery rates of H. ducreyi from surface cultures and biopsies obtained from mutant and parent sites were similar. These results indicate that the expression of glycoforms with sugar moieties extending beyond the heptose trisaccharide core is not required for pustule formation by H. ducreyi in humans