On the overtraining phenomenon of backpropagation neural networks

A very important subject for the consolidation of neural networks is the study of their capabilities. In this paper, the relationships between network size, training set size and generalization capabilities are examined. The phenomenon of overtraining in backpropagation networks is discussed and an extension to an existing algorithm is described. The extended algorithm provides a new energy function and its advantages, such as improved plasticity and performance along with its dynamic properties, are explained. The algorithm is applied to some common problems (XOR, numeric character recognition and function approximation) and simulation results are presented and discussed.     

Pervaporative transport mechanisms in phosphonium ionic liquid-based supported liquid membrane and its stability with actual fermentation broth feed

The pervaporative transport interactions between trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide ionic liquid-based membrane and the components of ABE fermentation broth were elucidated in this study. Acetone has a suggested viscosity decreasing effect on the ionic liquid and exhibited coupling effect with 1-butanol. Temperature increase consistently caused increase on 1-butanol permeance. The presence of acetic and butyric acids has no observed effect on 1-butanol and water permeation. No permeation of ethanol and acetic acid was noted, while butyric acid permeation can be suppressed by pH control. The membrane was proven stable in separating 1-butanol from actual fermentation broth for long period of time.     

Absolute surface coverage of tungsten-alumina catalysts

Absolute surface coverages (θ) of a series of tungsten-alumina catalysts prepared by the equilibrium adsorption method were determined by ion scattering spectroscopy (ISS) and low-temperature CO adsorption. The θ_CO values for the W catalysts were very similar to those obtained with the ISS method, for a given W loading. A linear increase in W coverage with increasing W loading, reaching ~55% coverage for the 13.1% W solid, was observed. The calculated W cross-sections (22.0- 24.5Ų/W) were in agreement with other reports in the literature. Due to the inherent limitations of each method, the combined use of ISS and low-temperature CO adsorption is recommended for estimating absolute surface coverages in tungsten-alumina catalysts.     

Social cost of electricity generation in Greece

This paper presents calculations of the social cost of electricity generation from fossil fuels in Greece. The interest of these calculations is that they allow a more realistic comparison between the actual price of electricity and the electricity produced by renewable energy sources, mainly wind and photovoltaic. The estimated social cost of energy was found to be in the range of 7.3–5.4 GRD · kWh⁻¹.     

Purification and characterization of an extracellular trypsin-like protease of Fusarium oxysporum var. lini

An alkaline serineprotease, capable of hydrolyzing Nalpha-benzoyl- dl arginine p-nitroanilide, was secreted by Fusarium oxysporum var. lini grown in the presence of gelatin as the sole nitrogen and carbon source. The protease was purified 65-fold to electrophoretic homogenity from the culture supernatant in a three-step procedure comprising QSepharose chromatography, affinity chromatography, and FPLC on a MonoQ column. SDS-PAGE analysis of the purified protein indicated an estimated molecular mass of 41 kDa. The protease had optimum activity at a reaction temperature of 45 degrees C and showed a rapid decrease of activity at 48 degrees C. The optimum pH was around 8.0. Characterization of the protease showed that Ca2+ and Mg2+ cations increased the activity, which was not inhibited by EDTA or 1,10-phenanthroline. The enzyme activity on Nalpha-benzoyl-DL arginine p-nitroanilide was inhibited by 4-(2-aminoethyl)-benzenesulfonyl fluoride hydrochloride, p-aminobenzamidine dihydrochloride, aprotinin, 3-4 dichloroisocoumarin, and N-tosyl-L-lysine chloromethyl ketone. The enzyme is also inhibited by substrate concentrations higher than 2.5 x 10(-4)M. The protease had a Michaelis-Menten constant of 0.16 mM and a V(max) of 0.60 mumol released product.min(-1).mg(-1) enzyme when assayed in a non-inhibiting substrate concentration. The activity on Nalpha-benzoyl- dl arginine p-nitroanilide was competitively inhibited by p-aminobenzamidine dihydrochoride. A K(i) value of 0.04 mM was obtained.     

Determination of the surface coverage of WO3/TiO2 catalysts by CO2 chemisorption

The surface coverage of a series of WO₃/TiO₂ catalysts prepared by incipient wetness impregnation was monitored by CO₂ chemisorption. The coverage of the TiO₂ support increases from 31±2% for the 3.3 wt% WO₃/TiO₂ catalyst to ca. 86±2% for catalysts with W loadings ≥10.3 wt% WO₃. The leveling off of the surface coverage for the high-loading catalysts has been attributed to the formation of W multilayers or bulk WO₃. The surface coverage values obtained by CO₂ chemisorption were consistent with those measured previously using ion scattering spectroscopy. The apparent suitability of CO₂ chemisorption for monitoring the surface coverage of TiO₂-supported catalyst systems, in contrast to previous results for Al₂O₃-supported systems, will be discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

1700 nm optical coherence microscopy enables minimally invasive,label-free,in vivo optical biopsy deep in the mouse brain

In vivo, minimally invasive microscopy in deep cortical and sub-cortical regions of the mouse brain has been challenging. To address this challenge, we present ...