Phase-reversal broad-band traveling-wave LiNbO/sub 3/ electrooptic modulator optimized for time-domain applications by a genetic algorithm

Several new nonperiodic spatial codes for phase-reversal coplanar waveguides (CPWs) used in the framework of the quasi-phase match technique (QPM) for broadening the optical response of z-cut LiNbO/sub 3/ electrooptic modulators (EOMs) are presented. The peculiarity of the codes is that they open the possibility for time-domain applications of EOMs based on nonperiodic QPM structures. They were obtained by using a specialized version of the genetic algorithm that generates an optimal length and number of the phase-reversal sections. The codes provide both flat amplitude and nearly linear phase frequency responses of the EOM within several frequency ranges important for fiber-optical/radio systems: from dc to 25, 40, and 90 GHz. The phase-reversal structures described here were optimized taking into account the CPW electrode losses and under the matching condition with 50 /spl Omega/-sources. They possess as low value of the drive voltage (V/sub /spl pi//, required for realization of 100% EO modulation efficiency) as possible for EOMs based on QPM, under the above conditions.     

Evaluation of anti-nociceptive effects of neuronal nicotinic acetylcholine receptor (NAChR) ligands in the rat tail-flick assay

In the present investigation, anti-nociceptive effects of neuronal nicotinic acetylcholine receptor (NAChR) ligands, (+)- and (-)-nicotine, cytisine, methylcarbamylcholine (MCC), dimethylphenylpiperazinium iodide (DMPP), and (+/-)-epibatidine were evaluated in the rat tail-flick assay both after subcutaneous (s.c.) and intracerebroventricular (i.c.v.) administration. The pharmacology of the tail-flick response to NAChR ligands after s.c. and i.c.v. routes was similar. Epibatidine was the most potent ligand examined with a longer duration of action than any other agonist. (-)-Nicotine was more active than (+)-nicotine indicating stereospecificity. ICV administration studies indicated an apparent partial agonist activity for (+)-nicotine in the tail-flick response. Tail-flick responses to NAChR agonists are independent of opioid and muscarinic pathways and appear to be mediated both by central and peripheral NAChR recognition sites. Central administration of MCC activates both NAChR and muscarinic anti-nociceptive mechanisms. Studies employing the alpha-adrenergic receptor alkylating agent, phenoxybenzamine or the noradrenergic neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), suggested that the NAChR-noradrenergic and NAChR-serotoninergic interactions play an important role in the tail-flick response. Studies employing a selective alpha-bungarotoxin-sensitive NAChR receptor antagonist, methyllycaconitine (MLA), suggested a minimal role for these receptors in the tail-flick response. The biochemical studies also indicated that a sub-population of NAChR receptors are located pre-synaptically on noradrenergic and/or serotoninergic pathways in the hippocampus.     

Stabilized variant of Streptomyces subtilisin inhibitor and its use in stabilizing subtilisin BPN'

Protein protease inhibitors could potentially be used to stabilize proteases in commercial products such as liquid laundry detergents. However, many protein protease inhibitors are susceptible to hydrolysis inflicted by the protease. We have engineered Streptomyces subtilisin inhibitor (SSI) to resist proteolysis by adding an interchain disulfide bond and removing a subtilisin cleavage site at leucine 63. When these stabilizing changes were combined with changes to optimize the affinity for subtilisin, the resulting inhibitor provided complete protease stability for at least 5 months at 31 degrees C in a subtilisin-containing liquid laundry detergent and allowed full recovery of the subtilisin activity upon the dilution that occurs in a North American washing machine.     

Refactoring object constraint language specifications

The object constraint language (OCL) plays an important role in the elaboration of precise models. Although OCL was designed to be both formal and simple, OCL specifications may be difficult to understand and evolve, particularly those containing complex or duplicated expressions. In this paper, we discuss how refactoring techniques can be applied in order to improve the understandability and maintainability of OCL specifications. In particular, we present several potentially bad constructions often found in OCL specifications and a collection of refactorings that can be applied to replace such constructions by better ones. We also briefly discuss how refactorings can be automated and how model regression testing can be used to increase our confidence that the semantics of an OCL specification has been preserved after manually performed refactorings.     

Surface‐Enhanced Raman Scattering Using Microstructured Optical Fiber Substrates

Microstructured optical fibers (MOFs) represent a promising platform technology for fully integrated next generation surface enhanced Raman scattering (SERS) sensors and plasmonic devices. In this paper we demonstrate silver nanoparticle substrates for SERS detection within MOF templates with exceptional temporal and mechanical stability, using organometallic precursors and a high‐pressure chemical deposition technique. These 3D substrates offer significant benefits over conventional planar detection geometries, with the long electromagnetic interaction lengths of the optical guided fiber modes exciting multiple plasmon resonances along the fiber. The large Raman response detected when analyte molecules are infiltrated within the structures can be directly related to the deposition profile of the nanoparticles within the MOFs via electrical characterization.     

A Bayesian network model for surface roughness prediction in the machining process

The literature reports many scientific works on the use of artificial intelligence techniques such as neural networks or fuzzy logic to predict surface roughness. This article aims at introducing Bayesian network-based classifiers to predict surface roughness (Ra) in high-speed machining. These models are appropriate as prediction techniques because the non-linearity of the machining process demands robust and reliable algorithms to deal with all the invisible trends present when a work piece is machining. The experimental test obtained from a high-speed milling contouring process analysed the indicator of goodness using the Naïve Bayes and the Tree-Augmented Network algorithms. Up to 81.2% accuracy was achieved in the Ra classification results. Therefore, we envisage that Bayesian network-based classifiers may become a powerful and flexible tool in high-speed machining.     

The Experience in Designing and Evaluating the High Performance Cluster Netuno

This paper presents the Netuno supercomputer, a large-scale cluster installed at Federal University of Rio de Janeiro in Brazil. A detailed performance evaluation of Netuno is presented, depicting its computational and I/O performance, as well as the results for two real-world applications. Since building a high- performance cluster for running a wide range of applications is a non-trivial task, some lessons learned from assembling and operating this cluster, such as the excellent performance of the OpenMPI library, and the relevance of employing an efficient parallel file system over the traditional NFS system, can be useful knowledge to support the design of new systems. Currently, Netuno is being heavily used to run large scale simulations in the areas of ocean modeling, meteorology, engineering, physics, and geophysics.