Dependency-directed control of text generation using functional unification grammar

In text generation, various kinds of choices need to be decided. In conventional frameworks, which we callone-path generation frameworks, choices are made in an order carefully designed in advance. In general, however, since choices depend on one another, it is difficult to make optimal decisions in such frameworks. Our approach to this issue is to introduce the revision process into the overall generation process. In our framework, revision of output texts is realized as dependency-directed backtracking (DDB). As well as Justification-based Truth Maintenance System (JTMS), we maintain dependencies among choices in a dependency network. In this paper, we propose an efficient implementation of DDB for text generation using functional unification grammar (FUG). We use bindings of logical variables in Prolog and destructive argument substitutions to decrease the overhead of handling a dependency network. This paper describes the algorithm in detail and shows the results of preliminary experiments to demonstrate the performance of our implementation.     

Synthesis of wide-pore alumina support from gibbsite

Gibbsite was treated in a series of primary alcohols at 250°C for 2 h. The surface area of the product increased with the increase in the carbon number of alcohol and reached a maximum when hexanol was used. Pore texture of aluminas, obtained by the calcination of these products, was investigated by means of the nitrogen adsorption technique. The aluminas prepared from the products of the treatment in alcohols other than propanol and butanol had a pore texture identical to the pore texture of the alumina from well-crystallized boehmite prepared by hydrothermal treatment of gibbsite. The pore texture of these aluminas was characterized by the presence of micropores. The aluminas prepared from the treatments in butanol and propanol had quite different pore texture. Micropores were not detected in these aluminas: instead, mesopores of c. 20 nm range were detected. These results are consistent with the reaction mechanisms for the formation of boehmite proposed in a previous paper on the basis of morphology of the products. In lower alcohols boehmite is formed by means of a resolution-crystallization mechanism, whereas in higher alcohols boehmite is formed by means of intraparticle hydrothermal reaction. In butanol and propanol, boehmite is crystallized from the alcoholic media and has a large population of crystal defects; therefore, pore texture of aluminas derived from these products resembles the aluminas from poorly crystallized aluminum hydroxides.     

Effect of trimebutine maleate on emptying of stomach and gallbladder and release of gut peptide following a solid meal in man

We investigated the effect of orally administered trimebutine maleate on gastric and gallbladder emptying and on the release of gut peptide, pancreatic polypeptide (PP), and gastrin in humans for 120 min after ingestion of a solid meal. Gastric emptying was measured by a radionuclide technique. Gallbladder emptying was estimated by real-time ultrasonography. The oral administration of 200 mg of trimebutine maleate significantly shortened the lag time in starting gastric emptying (P < 0.05). Considering gallbladder emptying, trimebutine significantly inhibited the fasting emptying induced by neural reflex. Postprandially, there was a tendency toward an accelerated gallbladder emptying in the early phase. Neither the maximal percentage of gallbladder emptying nor the time of peak gallbladder emptying were affected. Trimebutine significantly blunted the post-prandial PP response in the cephalic and gastric phases, reflecting a vagal-cholinergic activity (P < 0.05). The PP response in the intestinal phase was also blunted. Gastrin release was significantly augmented only during the period of fasting after drug administration (P < 0.05). The major effect of trimebutine maleate appears to be a shortening of the lag time at the start of gastric emptying probably via its anticholinergic activity.     

Dose-dependent suppression of toluene metabolism by isopropyl alcohol and methyl ethyl ketone after experimental exposure of rats

In order to examine possible suppression of toluene metabolism due to coexposure to other solvents, female Wistar rats were exposed for 8 h to toluene alone (at 50 or 100 ppm), or in combination with either methyl ethyl ketone (at 50, 100, 200 or 400 ppm) or isopropyl alcohol (at 50, 100, 200, 400, 800 or 1600 ppm). Urine samples were collected for 24 h after initiation of each exposure, and subjected to analysis for two toluene metabolites, hippuric acid and o-cresol, both by HPLC. The excretion of hippuric acid, a major metabolite, was not modified when the concentrations of methyl ethyl ketone or isopropyl alcohol were low, i.e. 100 ppm or below, whereas it was reduced when methyl ethyl ketone or isopropyl alcohol concentrations were twice or more times higher than that of toluene. There were no changes in any cases in excretion of o-cresol, a minor metabolite. The observation after coexposure to methyl ethyl ketone or isopropyl alcohol at low concentration is in line with the negative interaction between toluene and methyl ethyl ketone as well as between toluene and isopropyl alcohol after occupational exposures at low concentrations. Metabolic interaction may take place when the exposure intensity is high, as observed in the present study and also after experimental exposure of volunteers to toluene and m-xylene, or occupational exposure to benzene and toluene.     

Preparation of nanocomposite for optical application using ZnTe nanoparticles and a zero-birefringence polymer

Surface-modified ZnTe nanoparticles were mixed in a zero-birefringence polymer matrix. Transmission electron microscopy images revealed that aggregates of ZnTe nanoparticles with a diameter of ∼20 nm were uniformly dispersed in the polymer. The transmittance of ZnTe nanocomposites rapidly decreased at wavelengths shorter than the critical wavelength corresponding to the band gap of ZnTe nanoparticles, an effect which became significant as the volume fraction of particles increased. In this way, the optical characteristic of ZnTe nanoparticles was added to the polymer. The intrinsic zero-birefringence was confirmed in the heat-drawn ZnTe nanocomposites. As the ZnTe nanocomposites were left in air, a lowering of transmittance was observed. This was due to the oxidation of Zn and the resultant deposition of Te in the ZnTe nanocomposite, as the light absorption of Te is significant. The formation of oxygen non-permeable SiO₂ films onto the ZnTe nanocomposite by the sol-gel method was useful in preventing oxidation so that the decrement of transmittance decreased from 47.2% to 14.9% at 530 nm near the ZnTe band gap.     

Observation of nanostructure by scanning near-field optical microscope with small sphere probe

Step and terrace structure has been observed in an area of 1 μm×1 μm on the cleaved surface of KCl-KBr solid-solution single crystal by scanning near-field optical microscope (SNOM) with a small sphere probe of 500 nm diameter. Lateral spatial resolution of the SNOM system was estimated to be 20 nm from the observation of step width and the scanning-step interval. Vertical spatial resolution was estimated to be 5-2 nm from the observation of step height and noise level of photomultiplier tube (PMT). With applying a dielectric dipole radiation model to the probe surface, the reason why such a high spatial resolution was obtained in spite of the 500 nm sphere probe, was understood as the effect of the near-field term appeared in the radiation field equations.     

Formation of novel sintered composites by high-pressure crystallization of amorphous ceramics

A combination of chemical vapour deposition (CVD) and high-pressure (HP) techniques has achieved the fabrication of the zincblende form of boron nitride (z-BN)-based ceramic composites. The CVD technique provides amorphous B-N-X (X = aluminium, silicon or titanium). The HP technique renders the amorphous samples crystalline and decomposition into z-BN plus the respective nitride (-Si₃N₄ for instance) occurs. Compacts of the composites are obtained byin situ sintering under high pressure. The compacts exhibit peculiar microstructures composed of z-BN nano-crystals homogeneously dispersed in the nitride matrices.     

The infeasibility of using ten-ring irradiated grafts for tracheal allotransplantation even with omentopexy

A case is reported of methaemoglobinaemia presenting with recurrent fits in the absence of cyanosis. A low oxygen saturation measured on pulse oximetry that fails to improve with oxygen treatment, the presence of "chocolate brown" blood that does not change on exposure to air, and a high PaO2 arterial blood gas with oxygen therapy should support such a diagnosis. A diagnostic blood methaemoglobin level should be obtained.