Differential regulation of somatodendritic serotonin 5-HT1A receptors by 2-week treatments with the selective agonists alnespirone (S-20499) and 8-hydroxy-2-(Di-n-propylamino)tetralin: microdialysis and autoradiographic studies in rat brain

Single treatment with the serotonin (5-hydroxytryptamine) 5-HT1A receptor agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and alnespirone (S-20499) reduces the extracellular 5-HT concentration (5-HText) in the rat midbrain and forebrain. Given the therapeutic potential of selective 5-HT1A agonists in the treatment of affective disorders, we have examined the changes in 5-HT1A receptors induced by 2-week minipump administration of alnespirone (0.3 and 3 mg/kg/day) and 8-OH-DPAT (0.1 and 0.3 mg/kg/day). The treatment with alnespirone did not modify baseline 5-HText but significantly attenuated the ability of 0.3 mg/kg s.c. alnespirone to reduce 5-HText in the dorsal raphe nucleus (DRN) and frontal cortex. In contrast, the ability of 8-OH-DPAT (0.025 and 0.1 mg/kg s.c.) to reduce 5-HText in both areas was unchanged by 8-OH-DPAT pretreatment. Autoradiographic analysis revealed a significant reduction of [3H]8-OH-DPAT and [3H]WAY-100635 [3H-labeled N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridyl)cyclohexa necarboxamide x 3HCl] binding to somatodendritic 5-HT1A receptors (but not to postsynaptic 5-HT1A receptors) of rats pretreated with alnespirone but not with 8-OH-DPAT. In situ hybridization analysis revealed no change of the density of the mRNA encoding the 5-HT1A receptors in the DRN after either treatment. These data indicate that continuous treatment for 2 weeks with alnespirone, but not with 8-OH-DPAT, causes a functional desensitization of somatodendritic 5-HT1A receptors controlling 5-HT release in the DRN and frontal cortex.     

Adaptive modulation as a fade countermeasure. An olympus experiment

With the launch of the European Space Agency's Olympus-1 satellite, a whole new era of communication experiments in the 20/30 GHz bands will start. Of particular interest will be those experiments concerned with fade countermeasures for the very small aperture terminals (VSATs). Portsmouth Polytechnic's experiment will focus on adaptive modulation as a type of fade countermeasure, and this paper introduces and describes the whole concept. Based on the assumption that the performance of a VSAT operating at 20/30 GHz band will be affected to a major extent by amplitude scintillations and rain fading, the performance of a range of combinations of earth-station power amplifier and antenna characteristics is presented. An adaptive multi-phase shift keying technique is then compared with conventional systems in terms of availability and data throughput. It is shown that such a fade countermeasure contributes to increasing both the overall system availability and the total data throughput of a digital communication system, while the inevitable reductions in data rate occur smoothly.     

Laser beam processing of a SiC particulate reinforced 6061 aluminium metal matrix composite

SiC particulate reinforced 6061 Al metal matrix composites were laser beam cut using a 3kW continuous wave CO2 laser. The influence of laser processing parameters such as cutting speed, laser power, and shielding gas on the quality of the cuts were investigated. Optical microscopy, scanning electron microscopy and X-ray diffraction were used to analyse the laser treated zone. Experimental results show that 6061 Al metal matrix composites can cut be successfully using laser. A number of Al4C3/Al4SiC4 plates were formed in the heat affected zones due to a chemical reaction between Si and Al that occurred during the laser processing. This revised version was published online in November 2006 with corrections to the Cover Date.     

Cell-centered discontinuous Galerkin discretizations for two-dimensional scalar conservation laws on unstructured grids and for one-dimensional Lagrangian hydrodynamics

We present cell-centered discontinuous Galerkin discretizations for two-dimensional scalar conservation laws on unstructured grids and also for the one-dimensional Lagrangian hydrodynamics up to third-order. We also demonstrate that a proper choice of the numerical fluxes allows to enforce stability properties of our discretizations.     

The EuTrans Spoken Language Translation System

The EuTransAll project aims at using example-based approaches for the automatic development of Machine Translation systems accepting text and speech input for limited-domain applications. During the first phase of the project, a speech-translation system that is based on the use of automatically learned subsequential transducers has been built. This paper contains a detailed and mostly self-contained overview of the transducer-learning algorithms and system architecture, along with a new approach for using categories representing words or short phrases in both input and output languages. Experimental results using this approach are reported for a task involving the recognition and translation of sentences in the hotel-receptioncommunication domain, with a vocabulary of 683 words in Spanish. Atranslation word-error rate of 1.97% is achieved in real-timefactor 2.7 on a Personal Computer.     

Enhancement of media filter performance with coagulant use for treatment of diesel oil contaminated surface water

The objective of this study was to investigate the effect of coagulant addition on the filter performance and effluent quality during media filtration of surface water contaminated with diesel oil. A pilot scale multi-media filter system was operated under constant head conditions and at a constant loading rate of 30 L/min. The tests were conducted with and without coagulant addition prior to filtration of the surface water contaminated with diesel oil. Each filtration run was continued until the pressure drop increased to 0.7 bar. The source water with a turbidity of 10-15 NTU was prepared by mixing bentonite clay with tap water. The effect of coagulant addition on the performance of a multi-media filter for treatment of diesel oil contaminated source water was evaluated based on pressure change, filter run time before the filter clogged, and turbidity removal. The coagulant addition significantly improved the operational time of the media filter by reducing the rate of clogging. Both turbidity and PHC removal was achieved during the runs with coagulant addition.     

Nylon 6‐Polyesteramide Block Copolymers (NBC) and NBC/Phenolic Resin Composites, 1

Summary: A series of NBC/phenolic resin composites, containing 0, 1, 3, 5 or 7 wt.‐% of a powdered phenolic resin of different particle diameter, was prepared by the reaction injection molding (RIM) process. It was determined by SEM analysis that there exists a strong interaction between particles and matrix and that such interaction occurs through hydrogen‐type bonds as determined by FTIR analysis. According to the results it is thought that the glass transition temperature of the NBC/phenolic resin composites depends on two competing factors: the rigidity promoted by the hard solid filler and the flexibility imparted by the nylon 6 amorphous phase, whose proportion becomes more important with increasing amounts of phenolic resin particles. The elastic and flexural moduli of the NBC were improved by the addition of phenolic resin confirming the reinforcing effect of this filler. On the contrary, the impact strength diminishes with increasing amounts of phenolic resin, although this property is strongly dependent on the particle diameter.

SEM micrograph of the nylon 6‐polyesteramide block copolymer (80/20).     

Structure characterization of a laser-processed Al–Mo alloy

The surface structure of a laser-processed Al–Mo alloy has been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractory (XRD). The alloy was prepared by first laser alloying a mixture of Al and Mo powders into an Al substrate and then laser remelting the alloyed surface. Following the first laser alloying process, the needle-like equilibrium phases (Al5Mo(h) and Al5Mo(r)) are formed with a broad size ranges and distribute inhomogeneously in the -Al solid solution matrix. This coarse structure is replaced by a finer, uniform dispersion of dendrites after the subsequent laser remelting. Four basic types of solid states precipitates are observed: (1) irregularly shaped particles constructing the dendrites and having a nearly Al5Mo stoichiometry; (2) needle-like particles which is the Al5Mo (r) phase; (3) Faceted particles having a cubic structure with a stoichiometry close to Al7Mo; (4) tiny, equi-axed particles, with a rather narrow particle size distribution and a cubic structure. © 1998 Chapman & Hall