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Two types of porcine circovirus (PCV) have been isolated and are referred to as PCV1 and PCV2. PCV1 represents an apathogenic virus, whereas PCV2 is associated with post-weaning multisystemic wasting syndrome. The two PCVs are related, since they display about 70 % identity based on nucleotide sequences. In order to discriminate between common and type-specific antigens, an immunocytological approach was used following transfections with cloned circovirus DNAs, as well as recombinant proteins expressed by either baculovirus or plasmid vectors. The ORF1-encoded proteins in the two viruses were shown to be antigenically related, whereas the ORF2 proteins were recognized differentially by polyclonal anti-PCV2 antibodies. Furthermore, PEPSCAN analysis performed on overlapping fragments of the genes encoding part of ORF1 and the entire ORF2 and ORF3 led to the identification of five dominant immunoreactive areas, one located on ORF1 and four on ORF2. However, only some ORF2 peptides proved to be immunorelevant epitopes for virus type discrimination. The potential use of ORF2-derived antigens as diagnostic tools is demonstrated.

Porcine circovirus type 2 (PCV2) plays a crucial role in the pathogenesis of post-weaning multisystemic wasting syndrome (PMWS) in swine. As PCV2 displays significant homology with PCV1 (a non-pathogenic virus) at the nucleotide and amino-acid level, a discriminative antigen is needed for specific serological diagnosis. The ORF2-encoded capsid protein from PCV2 was used to develop an indirect enzyme-linked immunosorbent assay (ELISA). GST-fused capsid protein from PCV2 and GST alone (both expressed in recombinant baculovirus-infected cells) were used as antigens for serodiagnosis. The specificity of the ELISA for detection of PCV2 antibodies was demonstrated in sera from pigs experimentally infected with PCV1, PCV2 and other swine viruses. The semi-quantitative nature of the test was evaluated versus an immunoperoxidase monolayer assay (IPMA). The ELISA was performed on 322 sera from pigs in eight Brittany herds and compared with IPMA. The sensitivity (98.2%) and specificity (94.5%) of this test were considered suitable for individual serological detection. High PCV2 seroprevalence was found in sows and pigs at the end of the growth phase (18-19 weeks) in all eight herds. The seroprevalence in piglets (11-17 weeks) was statistically correlated with clinical symptoms of PMWS (93% in affected versus 54%, in non-affected farms). A cohort study performed in PMWS-free farms showed that 57% of piglets exhibited active seroconversion after 13 weeks, indicating that PCV2 infection occurred earlier in PMWS-affected piglets.

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The standard formalism of quantum theory is enhanced and denite meaning is given to the concepts of experiment, measurement and event. Within this approach one obtains a uniquely dened piecewise deterministic algorithm generating quantum jumps, classical events and histories of single quantum objects. The wave-function Monte Carlo method of Quantum Optics is generalized and promoted to the level of a fundamental process generating all the real events in Nature. The already worked out applications include SQUID-tank model and generalized cloud chamber model with GRW s p o n taneous localization as a particular case. Dierences between the present approach and quantum measurement theories based on environment induced master equations are stressed. Questions: what is classical, what is time, and what are observers are addressed. Possible applications of the new approach are suggested, among them connection between the stochastic commutative geometry and Connes' noncommutative formulation of the Standard Model, as well as potential applications to the theory and practice of quantum computers.

The degradation mechanism of MmNi,,,Co,,,Mn,4A1,, hydrogen storage alloy in nickel-metal hydride (Ni-MH) sealed batteries and effects of corrosion on cell performance during cycling are investigated. A general equation for the corrosion of AB, alloy is derived from analyses of corrosion products in cycled electrodes and measurements of negative discharge reserve. Water consumption due to alloy corrosion explains the increase of impedance during cycling while internal pressure evolution is directly linked to the loss of charge reserve. The parameters controlling the corrosion rate of AB, alloys are also examined. It is shown that the pulverization mode of the alloy particles rather than the surface reactivity to electrolyte explains the differences in cycle-life performance of alloys of various compositions. InfrocluctionAmong different electrochemical systems, Ni-MH batteries are one of the most promising energy sources for cordless appliances and electric vehicles (EVs) because they are nonpolluting and have higher energy-storage capabilities than Ni-Cd batteries. The use of sealed Ni-MR batteries in ENs or mobile phones requires good stability of the impedance during the whole cycle life as well as a limited increase of internal pressure at the end of charge. These two characteristics can be achieved by using hydrogen storage alloys with low corrosion rates.The first purpose of this study was to measure corrosion rates of AB, alloys during cycling and evaluate the consequences of this corrosion on sealed Ni-MR battery performance. The second purpose was to determine the main parameters responsible for AB, corrosion and particularly to separate the effects of the reactivity of the surface and the decrepitation phenomenon (particle pulverization), which continuously generates new surfaces. ExperimentalPreparation of alloy powders, electrodes, and cells.-Alloy ingots of composition MmNi,55Coai,Mn,4A1,, were prepared by melting Mm (Ce 50%, La 30%, Nd 15%, Pr 5%), Ni, Co, Mn, and Al in an induction furnace. After annealing, the ingots were mechanically ground into a powder of 35 jim in average diameter. A slurry containing metal hydride powder, a carbon black powder of high specific surface area, and styrene butadiene rubber was pasted into a foam nickel substrate. A carbon coating was then applied on the MR electrodes in order to improve their oxygen recombination ability. Positive electrodes were prepared by filling a nickel foam substrate with an active material consisting of Ni(OH), and cobalt compounds as conductive agents. Negative and positive electrodes as well as a polyamide separator were spirally wound to form cylindrical sealed cells (4/5 A size). Average capacity of the cells was 1.6 Ah at 1 C. The electrolyte was 8.7 M KOH-0.5 M NaOH-0.7 M LiOH.Electrical evaluation of the cells.-Cycle life was evaluated at room temperature using the following operating conditions: charge at 1 C for 1.2 h; discharge at I C to a cutoff potential of 0.9 V. Cells were periodically sampled for internal impedance, corrosion...

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