Auditory-evoked brainstem responses elicited by maximum-length sequences in normal and sensorineural ears

Auditory brainstem responses (ABRs) were recorded using pseudo-random pulse trains called maximum-length sequences (MLSs), which allow high stimulus rates and simultaneous recording from both ears, and were compared to ABRs obtained by conventional averaging. In normally hearing subjects, ABRs by MLSs produced the same waves as conventional ABRs, although wave latencies increased and amplitudes decreased. In normal as in sensorineural ears, MLS-ABR thresholds were similar to conventional ABR thresholds (except when binaural recordings were made) and were correlated with high-frequency audiometric thresholds. Binaural MLS-ABR recordings represent the individual response of each ear, as shown by recordings of monaurally deaf subjects.     

Portes NOR “ picosecondes ”tout optiques mises en série et connectées par doubleur de fréquence

The elementary cell to realize an all-optical data processing is a fast optical nor gate, compatible with a massively parallel architecture and large connection capabilities. It must be stressed that bistability is not at all obligatory in this respect. We report recent investigations on picosecond all optical nor gates in II-VI compounds (namely CdSe), that enable to realize a nor gate operating without Fabry-Pérot cavity. Transient induced absorption of photons, the energy of which is close to the bandgap energy, is due to exciton screening and gap shrinkage. We consider frequency doubling to associate and cascade several gates in order to build complex boolean functions. We demonstrate that the all optical modulation remains efficient even under violet pumping (consecutive to frequency doubling). The gate switching energy is 30 λJ/cm²to get a 4/1 contrast between the up and down output states of the nor device.     

Synthesis and protease-catalyzed hydrolysis of a novel hydrazinopeptide

In order to explore the potentiality of hydrazinopeptides as protease inhibitors, the resistance of the hydrazinopeptidic bond toward proteolysis was investigated. To this end, the novel hydrazinohexapeptide Z-Ala2-Pro-Val-hIle-Leu-OMe (1), where hIle represents hydrazinoisoleucine, was designed and synthesized together with the parent peptide Z-Ala2-Pro-Val-Ile-Leu-OMe (2). The interactions of 1 and 2 with human leukocyte elastase (HLE) and porcine pancreatic elastase (PPE) were analyzed comparatively. We observed that 1 behaved as a substrate for both elastases, without the formation of a stable acyl-enzyme as in the case of azapeptides. Compounds 1 and 2 were cleaved at the same site (-Val-parallel-NH-) with a slight delay of hydrolysis for 1 compared to 2 (kcat/KM for 1 vs. 2 decreased by a factor of 2.7 for the HLE-catalyzed hydrolysis at pH 8.0 and 25 degrees C). The presence of the hydrazinopeptide bond (-CONHNH-) in 1 reduced by a factor of 4.7 the apparent enzyme affinity without abolishing it. These results indicate that suitably designed hydrazinopeptides may represent interesting targets in the search for protease resisting pseudopeptides.     

An aggregation strategy of maximum size constraints in density-based topology optimization

Structural and Multidisciplinary Optimization - The maximum size constraint restricts the amount of material within a test region in each point of the design domain, leading to a highly constrained...