Cellular neural networks: a paradigm for nonlinear spatio-temporalprocessing

The paradigm of Cellular Neural Networks (CNNs)is going to achieve a complete maturity. In fact, from a methodological point of view, important results on their digitally programmable analog dynamics have been gained, completed with thousands of application routines. This has encouraged the spreading of a great number of applications in the most different disciplines. Moreover, their structure, tailor made for VLSI realization, has led to the production of some chip prototypes that, embedded in a computational infrastructure, have produced the first analogic cellular computers. This completes the framework and makes it possible to realize complex spatio-temporal and filtering tasks on a time scale of microseconds. In this paper some sketches on the main aspects of CNNs, from the formal to the hardware prototype point of view, are presented together with some appealing applications to illustrate complex image, visual and spatio-temporal dynamics processing     

Comparative survey of putrescine production from agmatine deamination in different bacteria

This article aims to study putrescine production in Lactobacillus hilgardii strain X(1)B, an agmatine degrader isolated from wine, and to compare it with three other different species, previously reported as putrescine producers from agmatine: Pseudomonas aeruginosa PAO1, Enterococcus faecalis ATCC11700 and Bacillus cereus CECT 148(T). The effect of different biogenic amines, organic acids, cofactors, amino acids and sugars on putrescine production was evaluated. In some cases, a similar effect was found in all the strains studied but the magnitude differed. Arginine, glucose and fructose showed an inhibitory effect, whereas the presence of agmatine induced the production of putrescine in all microorganisms. In other cases, the effect differed between P. aeruginosa PAO1 and the other microorganisms. Histamine and tyramine poorly influenced the utilization of agmatine, although a small increase in putrescine production was observed in P. aeruginosa PAO1. Succinate, spermidine and spermine also led to an increase in putrescine production in P. aeruginosa PAO1, whereas the succinate had no effect in the other microorganisms. Spermine and spermidine always produced a diminution in agmatine deamination. In this work, we have also demonstrated that pyridoxal 5-phosphate, Mg(2+) and Mn(2+) had no effect on putrescine production from agmatine. Results presented in this paper indicate differences in regulation mechanisms of agmatine deiminase pathway among P. aeruginosa PAO1 and L. hilgardii X(1)B, E. faecalis ATCC11700 and B. cereus CECT 148(T). These results are significant from two points of view, first food quality, and second the toxicological and microbiological aspects. It should be taken into account that putrescine, whose origin is still controversial, is quantitatively the main biogenic amine found in food.     

Morphologic variations in bacteria under stress conditions: near-field optical studies

The morphologic and structural variations suffered by cells of a population of Pseudomonas aeruginosa ATCC 27853 under stress conditions were investigated by using scanning near-field optical microscopy. The analysis of the images, supported by microbiological data, showed that the bacteria evolved from the initial distribution of rod-shaped cells of standard size to a population with structural and morphologic modifications. The detection of variations in the optical reflectivity over a subwavelength scale (< or = 100 nm), combined with the concurrently acquired topographical signal, allowed the visualisation of rod-shaped bacteria going towards a lytic process and entire "U"-shaped cells. In the latter cells, which derived from a morphology refolding of rod bacteria, cellular matter seemed to rearrange itself to attain a coccoid stress resistant form, responsible for the residual viability of the population.     

Effect of vanadia loading in propane oxidative dehydrogenation on V2O5/SiO2 catalysts

The influence of V₂O₅ loading on the catalytic behaviour of V₂O₅/SiO2₂ catalysts in the oxidative dehydrogenation of propane to propylene (POD) has been investigated. The different activity-selectivity pattern of low (5 wt%) and highly (>10 wt%) loaded V₂O₅/SiO₂ catalysts is explained in terms of different surface vanadia species.     

Segmental up-regulation of transforming growth factor-beta in the pathogenesis of primary megaureter. An immunocytochemical study

OBJECTIVE: To examine the maturational-delay hypothesis of primary megaureter (PM), i.e. that the condition arises by a segmental maturational delay of the ureteric wall that can resolve spontaneously within the first year of life, using comparative immunocytochemistry of ureters resected from infants and from homologous pre-natal ureters. MATERIALS AND METHODS: Seventeen distal urinary tracts were obtained from children with PM who were referred for surgery (aged 6 months to 8 years, mean 2.1 years). These were compared with ureteric buds obtained from 11-week-old human and 11- to 38-week-old calf fetuses. The samples were immunostained using a monoclonal antibody specific for transforming growth factor beta (TGF-beta). RESULTS: The histological appearances of the narrowed ureteric segments from patients under 18 months old were like the fetal ureteric buds at 26-38 weeks of gestation. Positive TGF-beta immunoreactions were detected in the longitudinal muscle layer in the ureter from patients 6-12 months old. Such reactions weakened progressively in those patients older than 1 year, becoming negative in all children older than 3 years. The TGF-beta immunolabelling in resected ureters was closely similar to that in fetal ureters from 20 to 26-week old calves. CONCLUSIONS: From these results, PM should be ascribed to a segmental developmental delay of the terminal ureter arising at about 20 weeks of gestation, with a possible pathogenetic involvement of autocrine TGF-beta overexpression.     

The posterior scalping flap

The posterior scalping flap is described. Hopefully, it brings another alternate method of facial reconstruction and obviates some of the problems previously existing. It is capable of resurfacing any part or the whole of the hemiface or forehead. It offers an excellent method for facila resurfacing. Further refinements and sophistications are necessary.     

Magnetic Properties of Fe-Implanted ZnO Nanotips Grown by Metal-Organic Chemical Vapor Deposition

Fe ions were implanted into well-aligned single-crystal ZnO nanotips grown on SiO₂/quartz substrates using metal-organic chemical vapor deposition (MOCVD). The Fe ion concentration distribution within a single nanotip is mapped by electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) and the nanotips imaged by high-resolution transmission electron microscopy (TEM). X-ray absorption spectroscopy (XAS) identified the presence of Fe²⁺ and Fe³⁺ ions in both as-implanted and annealed samples. However, Fe³⁺ ion concentration increased during postannealing. Superconducting quantum interference device (SQUID) measurements show that the as-implanted and postannealed ZnO nanotips are ferromagnetic at room temperature. The observed ferromagnetism in the as-implanted nanotips is primarily attributed to the near surface 10-nm region that has high Fe concentration. The saturation magnetization reduces after annealing.     

Effect of clay type and loading on thermal,mechanical properties and biodegradation of poly(lactic acid) nanocomposites

PLA nanocomposites based on two different clays (CLO30B and SOMMEE) at 5 and 10 wt.% clay loading were prepared by melt-blending, obtaining a good level of clay dispersion as well as considerable thermo-mechanical improvements in PLA, according to WAXS, SEM, TEM, DMTA and tensile strength analysis.Addition of clays induced PLA crystallization by nucleation, especially upon addition of SOMMEE, promoting kinetics and extent of crystallization of the polymer, especially at high clay content. Concerning the thermal and mechanical properties, the highest improvements in PLA matrix were obtained upon 10% clay addition, especially SOMMEE, becoming more noticeable with increasing temperature.An effective degradation of PLA and nanocomposites in compost at 40 °C was also achieved. It was found that addition of nanoparticles, especially SOMMEE, accelerated the degradation process of PLA, particularly at higher clay content, probably due to catalysis by the hydroxyl groups belonging to the silicate layers surface and/or to their organic modifier.