III-V/silicon first order distributed feedback lasers integrated on SOI waveguide circuits

Heterogeneously integrated III-V-on-silicon first order distributed feedback lasers utilizing an ultra-thin DVS-BCB die-to-wafer bonding process are reported. A novel design exploiting high confinement in the active waveguide is demonstrated. 5 mW output power coupled to a silicon waveguide, 40 dB side mode suppression ratio and continuous wave operation up to 60°C is obtained

Modelling credit spreads with time volatility, skewness, and kurtosis

This paper seeks to identify the macroeconomic and financial factors that drive credit spreads on bond indices in the US credit market. To overcome the idiosyncratic nature of credit spread data reflected in time varying volatility, skewness and thick tails, it proposes asymmetric GARCH models with alternative probability density functions. The results show that credit spread changes are mainly explained by the interest rate and interest rate volatility, the slope of the yield curve, stock market returns and volatility, the state of liquidity in the corporate bond market and, a heretofore overlooked variable, the foreign exchange rate. They also confirm that the asymmetric GARCH models and Student-t distributions are systematically superior to the conventional GARCH model and the normal distribution in in-sample and out-of-sample testing

Binding of 4-methylumbelliferyl α-d-mannopyranoside to tetrameric Concanavalin A: fluorescence temperature-jump relaxation study

The kinetics of saccharide binding to the tetramer form of concanavalin A have been studied at pH 7.2 with the temperature-jump method. 4-Methylumbelliferyl alpha-D-mannopyranoside was used as a ligand; its fluorescence is totally quenched upon binding. A single relaxation of ligand fluorescence (τ= 20–400 ms) was observed and was investigated at three different temperatures, using kinetic titration and dilution types of experiments. The concentration dependence of the relaxation time and amplitude were consistent with a single-step bimolecular association and independent binding sites. In the temperature range 13–24 °C the association and dissociation rate parameters are in the range (6–10) × 104 M−1 s−1 and (1.4–3.2) s−1 respectively, corresponding to activation energies for the forward and reverse reactions equal to approx. 13 and 8 kcal/mol (54 and 33 kJ/mol) respectively. Two additional relaxations of protein fluorescence (3 ms and larger than 1 s at 25 °C) were unaffected by carbohydrate binding. Tetrameric concanavalin A shows carbohydrate binding parameters that are almost identical to those of native or derivatized dimeric concanavalin A

Binding kinetics of methyl α-D-mannopyranoside to Concanavalin A: temperature-jump relaxation study with 4-methylumbelliferyl α-D-mannopyranoside as a fluorescence indicator ligand

The binding of methyl alpha-D-mannopyranoside and methyl alpha-D-glucopyranoside to concanavalin A has been investigated by the temperature-jump relaxation kinetic technique using the competitive inhibitor 4-methylumbelliferyl alpha-D-mannopyranoside as an indicator of the binding reaction. The analysis shows that these saccharides bind to concanavalin A in a single bimolecular step. The binding parameters are compared to those of derivatized carbohydrates which have previously been used to study the binding of saccharides to concanavalin A. The similarity of the association rate constants indicates that a common process is involved in the binding of all carbohydrates to concanavalin A. The different affinities of saccharides for the lectin are primarily due to the different dissociation rate constants. A discussion of the proposed mechanism is given under the Appendix to clarify the fact that one of the observed relaxation times is faster than is possible with only the kinetic indicator reaction