Equilibrium analysis of cellular neural networks

Cellular neural networks (CNNs) are dynamical systems, described by a large set of coupled nonlinear differential equations. The equilibrium-point analysis is an important step for understanding the global dynamics and for providing design rules. We yield a set of sufficient conditions (and a simple algorithm for checking them) ensuring the existence of at least one stable equilibrium point. Such conditions give rise to simple constraints, that extend the class of CNNs, for which the existence of a stable equilibrium point is rigorously proved. In addition, they are suitable for design and easy to check, because they are directly expressed in term of the template elements.     

On state equations of two‐level quantum systems in a thermal environment

The state equations of open two‐level quantum systems, which form the building blocks of quantum cellular neural networks, are studied in arbitrary representations. It is shown that the dissipation matrix, that under the usual assumptions is diagonal in the energy representation, such remains if and only if the coupling between the states induced by an external field is real and infinitesimal. Copyright © 2004 John Wiley & Sons, Ltd.     

An Application of Extreme Value Theory for Measuring Financial Risk

Assessing the probability of rare and extreme events is an important issue in the risk management of financial portfolios. Extreme value theory provides the solid fundamentals needed for the statistical modelling of such events and the computation of extreme risk measures. The focus of the paper is on the use of extreme value theory to compute tail risk measures and the related confidence intervals, applying it to several major stock market indices.     

Comparative study of 2 groups of paranoid syndromes appearing at different ages

Clinical study of two groups of females beyond age of 65, institutionalized for delusional manifestations of schizophrenic nature and presenting also, at the time of examination, a pronounced paranoid state. In the first group: the manifestations had arisen before the age of 45. In the second group, after the age of 65. This study has demonstrated certain psychopathological characteristics suggesting the presence of personality problems definitely more profound in patients of the first group: autistic state, asthenia, thought disorder, incoherence and vagueness of delusional subjects, ordinarily much more unreal are characteristics of the first group in comparison to the second. This seems to bring evidence that these two paranoid states (paranoid schizophrenia in adult age and paranoid state in senility) are, at first sight, pathological entities based on personality problems of very different intensity.     

Exposure to phenol: analysis of environmental and urinary concentrations of phenol in a group of exposed subjects

The underlying metabolism and daily energy losses were studied in 22 patients with malignant tumours of the stomach and in 51 patients with pyloric stenosis and duodenal ulcer, preoperatively and over the first 9 days postoperatively. The preoperative studies revealed a rise in the underlying metabolism rate by 43.7 and 28.2%, respectively in the patients of both groups as compared to the metabolism in healthy individuals of the same sex, weight, height and age. Postoperatively, the underlying metabolism rate dropped in the oncological patients to the level seen in healthy people, whereas in duodenal ulcer patients the metabolic rates remained elevated. The patients' energy requirements are calculated respectively as 25-30 and 41-45 kcal per 1 kg body weight daily.     

How to Strip a Model to Its Essential Elements

Econometric models can be considered as a quantified representation of current economic theory. The paper suggests a procedure to check the correspondence between theory and practice. After an introduction about methodological aspects, a model of the Canadian economy is reduced by appropriate aggregation of the variables. Its condensed structure is then analysed, in order to investigate especially some noteworthy economic circuits such as financial flows and investment. The whole approach is strictly qualitative, based exclusively on the causal structure of the model. The results remain therefore consistent with any quantification of the model.     

Chemical characteristics and mutagenic activity of PM10 in Torino, a northern Italian city

Epidemiological studies of particulate matter (PM) have associated PM mass, as well as certain individual components of PM such as secondary particulate with adverse human health effects. For example genotoxic effects attributed to PM may relate to the content of organic compounds but also to the oxidative DNA damage generated by transition metals like iron. However the exact physiochemical mechanism by which PM produces adverse effects is not clear. The aims of this study were to evaluate (1) concentrations of PM10, (2) amounts of bioavailable iron associated with PM10, (3) amounts of secondary particulate expressed as SO4(=) and NO3(-) and (4) the mutagenic activities of PM10 organic extracts. Sampling was carried out in a meteochemical station located in Torino, a northern Italian city with high levels of PM10. The mean PM10 concentration in the considered period was 46.1+/-28.8 microg/m3, the iron mean concentration was 0.83 microg/m3 (+/-0.65 microg/m3) and the bioavailable Fe was 5.7% (+/-4.4%). The data showed that secondary particulate matter (as sum of sulfates and nitrates) constituted about 47% of PM10 total mass. Both iron and secondary species concentrations were positively associated with PM10 levels. Seasonal variations of PM10 concentration, iron level and secondary species amount were significant. Samples were tested for mutagenicity with Salmonella typhimurium strains TA98 and TA100, with and without metabolic activation and a positive response was observed especially for TA98. There were positive statistical associations between mutagenicity and PM10, bioavailable iron, sulfates and nitrates concentrations. Therefore, these results showed the usefulness of this biological approach for monitoring PM10.