A novel approach to complex target recognition using RCS wavelet decomposition

A novel approach to complex target recognition using wavelet decomposition of the radar cross section is introduced. The analysis technique is presented, and it shown how it can be implemented using MATLAB software. Applications in the radar field are then investigated, both for simple and complex targets. The results obtained show that this technique is very promising and yields recognition levels difficult to achieve with any other available technique.     

Kinetics modeling of a modified epoxy–amine formulation cured by thermal and microwave energy

The reaction kinetics of a rubber-modified epoxy formulation cured by microwave or thermal energy were investigated. Two phenomenological models were developed to predict the time and temperature dependence of the conversion for the neat and the modified systems. Good agreement was observed between the kinetic models and experimental results generated by chromatographic and calorimetric techniques. The same kinetic behavior was observed whatever the curing process (conventional or microwave heating). © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 543–552, 1998     

Catalytic wet peroxide oxidation of phenol over Fe-exchanged pillared beidellite

This study presents an evaluation of the catalytic performances of a Fe-exchanged Al-pillared synthetic beidellite for the wet hydrogen peroxide oxidation of phenolic aqueous wastes. The catalyst was prepared by a cation doping technique, its properties being determined by DRX, BET and chemical analysis techniques. All the tests were performed on a laboratory scale set-up.Important factors affecting catalyst activity and phenol removal efficiencies were studied, i.e. the effect of pH, temperature, catalyst concentration and the stability of the catalyst. The experimental results indicate that the use of this catalyst allows a total elimination of phenol and a significant removal of chemical oxygen demand, without significant leaching of Fe ions. Thus, considering the lowest Fe concentrations in solution after oxidation, at pH=5, 50 degrees C, and 180 min. COD removal efficiency of 87.9% was obtained. It was also observed that by using this catalyst, it is possible to extend the range of pH values for which Fenton-type oxidations can occur.     

Signal-to-noise ratios of array receiving systems with internal losses

A formulation of the signal-to-noise ratio (SNR) for a typical antenna array receiving system that is more complete than those now available in the literature is presented. In addition to the external noise accepted by the array, it includes all forms of internal noise generated by the lossy components of the system. Distinct measurable factors account for distinct noise sources. For the analysis, it is shown that the actual lossy system can be replaced by an equivalent lossless system with appropriate attenuators. The formulation is used to design the combining network that will optimize the receiving system SNR for signals incident from a given direction in the presence of a known external noise distribution. The theory is applied to a specific array antenna receiving system operating under a variety of noise conditions, internal as well as external. A discussion of some typical results is presented.     

Mutual Coupling in the Signal-to-Noise Ratio Optimization of Antenna Arrays

In terms of network parameters defined at the input terminals, expressions applicable to any array configuration are derived for the S/N ratio. The formulation is made in such a way that it becomes possible to account for coupling effects that arise from the geometry of the array and the current distributions on the elements of the array. Since the S/N ratio consists of the ratio of two Hermitians forms, known techniques are used for its optimization. Comparisons with simplified theories are given that demonstrate clearly the importance of mutual coupling in many cases. Numerical results for a 4-element circular array are included for two idealized noise temperature distributions. Applications of this theory to EMC fields are also mentioned.     

Clinical features of fatal familial insomnia: phenotypic variability in relation to a polymorphism at codon 129 of the prion protein gene

Fatal Familial Insomnia is a hereditary prion disease characterized by a mutation at codon 178 of the prion protein gene cosegregating with the methionine polymorphism at codon 129 of the mutated allele. It is characterized by disturbances of the wake-sleep cycle, dysautonomia and somatomotor manifestations (myoclonus, ataxia, dysarthria, spasticity). PET studies disclose severe thalamic and additionally cortical hypometabolism. Neuropathology shows marked neuronal loss and gliosis in the thalamus, especially the medio-dorsal and anterior-ventral nuclei, olivary hypertrophy and some spongiosis of the cerebral cortex. Detailed analysis of 14 cases from 5 unrelated families showed that patients ran either a short (9.1 +/- 1.1 months) or a prolonged (30.8 +/- 21.3 months) clinical course according to whether they were homozygote met/met or heterozygote met/val at codon 129. Moreover, homozygotes had more prominent oneiric episodes, insomnia and dysautonomia at onset, whereas heterozygotes showed ataxia and dysarthria at onset, earlier sphincter loss and epileptic Grand Mal seizures; they also displayed more extensive cortical involvement on PET and at postmortem examination. Our data suggest that the phenotype expression of Fatal Familial Insomnia is related, at least partly, to the polymorphism at codon 129 of the prion protein-gene.     

The cell cycle gene SKP1 is regulated by light in postnatal rat brain

During the early postnatal phase of high neuronal plasticity, an altered visual input leads to great modifications of visual cortex organization [Y. Frégnac, M. Imbert, Development of neuronal selectivity in primary visual cortex of cat, Physiol. Rev., 64 (1984) 375-434; D.H. Hubel, T.N. Wiesel, S. LeVay, Plasticity of ocular dominance columns in monkey striate cortex, Philos. Trans. R. Soc. London, Ser. B, 278 (1977) 377-409.]. We used refined differential screening of an organized cDNA library to identify the genes that may participate in this plasticity. We isolated a candidate plasticity gene encoding for a 163 aa protein that is closely related to the human and yeast Skp1p, a key factor in cell cycle progression [C. Ba?, K. Hofman, L. Ma, M. Goebl, J.W. Harper, S.J. Elledge, SKP1 connects cell cycle regulators to the ubiquitin proteolysis machinery through a novel motif, the F-box, Cell, 86 (1996) 263-274; C. Connelly, P. Hieter, Budding yeast SKP1 encodes an evolutionary conserved kinetochore protein required for cell cycle progression, Cell, 86 (1996) 275-285; H. Zhang, R. Kobayashi, K. Galaktionov, D. Beach, p19Skp1 and p45Skp2 are essential elements of the cyclin A-CDK2 S phase kinase, Cell, 82 (1995) 915-925.]. Northern blot analysis showed that the expression of SKP1 (Skp1p gene) dramatically decreased after 2 h of light stimulation in the visual cortex of young dark-reared rats. This down regulation lasted at least 72 h. It was specific for the critical period as we did not observe any significant regulation of SKP1 mRNA by light in adult dark-reared rat brain. The down regulation was observed in the superior colliculus but also in the frontal cortex and in the hippocampus. The fact that this down regulation was not restricted to the visual system, suggested that it could be produced by dark rearing-induced hormonal changes. The significance of SKP1 expression in the brain and its regulation are discussed.     

The impact of selective amygdala, orbital frontal cortex, or hippocampal formation lesions on established social relationships in rhesus monkeys (Macaca mulatta).

Social dominance, personality ratings, and frequency, duration, and timing of social behaviors were measured pre- and postsurgically in 6 groups of rhesus monkeys (Macaca mulatta), each consisting of 1 sham-operated control and 1 monkey each with a selective amygdala, hippocampal, or orbital frontal cortex lesion. Unlike previous reports, none of the operated groups showed changes in social dominance postsurgery, although changes in other measures varied by lesion site. Although sham-operated monkeys displayed heightened avoidant, anxious, and aggressive behaviors, those with hippocampal lesions also showed increased exploration and excitability, along with reduced responses to affiliative signals. Amygdala lesions yielded several personality changes that precluded positive social interactions (increased exploration and excitability, decreased affiliation and popularity) and altered responses to threatening social signals. By contrast, monkeys with orbital frontal lesions were involved in more aggressive interactions and responded differently to both affiliative and threatening signals. Although several findings differ from earlier nonhuman primate studies, they are largely in agreement with human data and emphasize the context-specific nature of social behavior studies. Interpretation of results in relation to cognitive processes mediated by each structure is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation of new microporous titanium pillared kenyaite materials active for the photodegradation of methyl orange

In recent years, layered silicates have extensively been used to design new nanomaterials through functionalization. In this work, the lamellar sodium silicates magadiite and kenyaite have been hydrothermally synthesized in presence of ethanol as organic co-solvent. Materials of high purity and high crystallinity were obtained after only 24 h of crystallization at a temperature of 180 °C for kenyaite and a temperature of 150 °C for magadiite. It appears that the presence of ethanol in the synthesis medium tends not only to increase the crystallization rate, but also to stabilize the formation of magadiite.The as-synthesized Na-kenyaite was used as precursor for the preparation of titanium pillared clay materials. The resulting microporous titanium oxide pillared kenyaite materials exhibit large specific surface areas up to 180 m² g^?1 with a Ti contents up to 24 wt% and are active for the photocatalytic degradation under UV light irradiation of the organic dye methyl orange in water.