Quantum Statistics of Unimolecular Multiphoton Dissociation with Absorption of Ultraviolet Radiation

Abstract

The interaction Hamiltonian for the absorption of a u.v. photon by a dissociating fragment has been formulated within the framework of a second quantization, by means of transition operators. The master equation and the moments have been determined using some approximations. The time variation of the u.v. photon number provides information about the stimulated emission of u.v. photons. The equation of motion for diagonal matrix elements of the reduced-density operator has been solved using Laplace and Zubairy methods. The latter procedure has been extended for the case of unimolecular multiphoton dissociation on the assumption that the system does not show any relaxation. The Zubairy distribution function permits the study of the time variation of u.v. photons absorbed by a polyatomic fragment, which has been studied experimentally. The second-order degree of coherence and the variance have been determined assuming that the i.r. distribution is initially coherent and the u.v. is chaotic. The i.r. distribution shows an antibunching effect.     

Fe, Cu and Zn distribution in different components of commercial infant formulas

Fe, Cu and Zn determination by AAS was performed in 35 infant formula samples from different manufacturers. The trace element content was studied in whole, fat and whey milk, and different chemometric tools have been used in order to observe differences or correlations between infant formulas fortified with inorganic salts (iron, copper and zinc sulphates) or with organic and inorganic salts (iron and copper gluconates, or zinc and iron lactates and zinc oxides). Principal-components analysis (PCA) achieved a reduction from nine variables to three (accounting for 80.8% of the total variability), and some differences between infant formula from the two groups were observed.Cluster analysis gave similar results as PCA. Linear discriminant analysis (LDA) allowed the classification of infant formulas in two categories or classes: the first class formed by samples fortified with inorganic salts (category A) and the second one by samples fortified with organic and inorganic salts (category B). The percentages of samples correctly classified were 96.1 and 100.0 for the categories A and B, respectively. After the application of the soft independent modelling of class analogy (SIMCA) approach, percentages of cases correctly assigned of 87.5 and 12.5 were achieved for the categories A and B, respectively. However, it must be said that the application of SIMCA led to bad results because of the small number of sample used, mainly in category B.     

Main achievements of FP-4 research in reactor safety

This summary paper deals with the strategy, the organisation and main achievements of the 67 multi-partner projects cosponsored by the European Union (EU) as ‘indirect actions’ (shared-cost and concerted actions) and co-ordinated under seven clusters, each devoted to one key safety issue in nuclear reactor safety, as they were presented at FISA-99. The fundamental safety objective for nuclear power plants (NPPs) consists in protecting the public and the environment from the harmful effects resulting from ionising radiations. The 4th Euratom framework programme 1994–1998 (FP-4) has been carrying out research with this objective both through ‘indirect actions’ and through ‘direct actions’ in co-operation with the Joint Research Centre of the European Commission (EC). The total cost of this research programme was 62.8 million, out of which 34.2 million was contributed by the EU budget. Besides technological safety requirements, socio-economic aspects are becoming increasingly important due to the level of public and political acceptance and to the economic pressure of deregulated electricity markets. It is shown that research conducted in the Euratom framework may contribute to meet these requirements, thereby maintaining nuclear power as a competitive and sustainable option for the energy policy of the European Union.     

Influence of deposited metal structures on the failure mechanisms of silicon-based components

Miniaturised silicon-based multilayer chips are nowadays widespread as semiconductor components for the mobile device technology. The use of special processing and integration procedures requires such materials to possess a definite mechanical strength to ensure the functionality of the entire device. The strength and mechanical reliability of such components can be described by the Weibull theory, and is highly influenced by the geometry of the metallisation and other near-surface functional layers. In this work, we attempt to clarify the mechanisms leading to the failure of the metallised side of Si-chip components. The combined use of Finite Elements (FE) and Focused Ion Beam (FIB) analyses allowed recognising that cracks are induced in the metal-oxide-silicon interfacial area well before complete failure of the component. Such cracks have a crucial role in the lower strength and higher Weibull modulus observed on the metallised side.     

Eicosanoids and fat emulsions in acute respiratory distress syndrome patients

Laparoscopic splenectomy has been accepted as a feasible extension of minimally invasive surgery, which has undergone dramatic improvements in both technology and instrumentation. We performed a laparoscopic splenectomy in a 7-year-old girl with hereditary spherocytosis. The patient recovered rapidly and returned to unrestricted activities quickly. The appropriate positioning of each laparoscopic port is essential for a good operative view and smooth access. It is also important to dissect the hilum of the spleen meticulously. Laparoscopic splenectomy in the pediatric age group appears to be another promising extension of laparoscopic surgery.