Dispersion of prion protein deposits around blood vessels in variant Creutzfeldt-Jakob disease

In variant Creutzfeldt-Jakob disease (vCJD), a disease linked to bovine spongiform encephalopathy (BSE), florid-type prion protein (PrP(sc)) deposits are aggregated around the larger diameter (> 10 µm) cerebral microvessels. Clustering of PrP(sc) deposits around blood vessels may result from blood-borne prions or be a consequence of the cerebral vasculature influencing the development of the florid deposits. To clarify the factors involved, the dispersion of the florid PrP(sc) deposits was studied around the larger diameter microvessels in the neocortex, hippocampus, and cerebellum of ten cases of vCJD. In the majority of brain regions, florid deposits were clustered around the larger diameter vessels with a mean cluster size of between 50 µm and 628 µm. With the exception of the molecular layer of the dentate gyrus, the density of the florid deposits declined as a negative exponential function of distance from a blood vessel profile suggesting that diffusion of molecules from blood vessels is a factor in the formation of the florid deposits. Diffusion of PrP(sc) directly into the brain via the microvasculature has been demonstrated in vCJD in a small number of cases. However, the distribution of the prion deposits in vCJD is more likely to reflect molecular 'chaperones' diffusing from vessels and promoting the aggregation of pre-existing PrP(sc) in the vicinity of the vessels to form florid deposits.

Pathological changes in the sporadic and variant forms of Creutzfeldt-Jakob Disease (CJD) are spatially related to blood vessels

The objective of this article was to determine whether the pathological changes of Creutzfeldt-Jacob disease (CJD) were related to the brain microcirculation. Hence, the spatial correlations between the vacuolation, prion protein (PrP) deposits, and the blood vessel profiles were studied in immunolabelled sections of the cerebral cortex, hippocampus, and cerebellum in two subtypes of CJD, viz., sporadic CJD (sCJD) and variant CJD (vCJD). In sCJD, both the vacuolation and the ‘synaptic-type’ PrP deposits were spatially correlated with the microvessels; the PrP deposits being more strongly correlated than the vacuoles. In vCJD, there were no significant spatial correlations between either the vacuolation or the diffuse-type of PrP deposit and the microvessels. By contrast, a consistent pattern of spatial correlation was observed in gyri of the cerebral cortex between the florid PrP deposits and microvessels. In both sCJD and vCJD, the frequency of positive spatial correlations was similar in the different gyri of the cerebral cortex and in the upper compared with the lower laminae. In conclusion, the microcirculation may be more significantly involved in determining the pathological changes in sCJD than in vCJD. The spatial correlations of the florid PrP deposits in vCJD and the synaptic deposits in sCJD and the blood vessels may be attributable to factors associated with the microcirculation which enhance the aggregation of PrP molecules rather than representing a possible haematogenous spread of the disease.

Induction heating of wild steel vessels in a pulsating field

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High stress monitoring of prestressing tendons in nuclear concrete vessels using fibre-optic sensors

Maintaining the structural health of prestressed concrete nuclear containments is a key element in ensuring nuclear reactors are capable of meeting their safety requirements. This paper discusses the attachment, fabrication and characterisation of optical fibre strain sensors suitable for the prestress monitoring of irradiated steel prestressing tendons. The all-metal fabrication and welding process allowed the instrumented strand to simultaneously monitor and apply stresses up to 1300 MPa (80% of steel's ultimate tensile strength). There were no adverse effects to the strand's mechanical properties or integrity. After sensor relaxation through cyclic stress treatment, strain transfer between the optical fibre sensors and the strand remained at 69%. The fibre strain sensors could also withstand the non-axial forces induced as the strand was deflected around a 4.5 m bend radius. Further development of this technology has the potential to augment current prestress monitoring practices, allowing distributed measurements of short- and long-term prestress losses in nuclear prestressed-concrete vessels. © 2014 Elsevier B.V.

Rotation invariant iris feature extraction using Gaussian Markov random fields with non-separable wavelet

Rotation invariance is important for an iris recognition system since changes of head orientation and binocular vergence may cause eye rotation. The conventional methods of iris recognition cannot achieve true rotation invariance. They only achieve approximate rotation invariance by rotating the feature vector before matching or unwrapping the iris ring at different initial angles. In these methods, the complexity of the method is increased, and when the rotation scale is beyond the certain scope, the error rates of these methods may substantially increase. In order to solve this problem, a new rotation invariant approach for iris feature extraction based on the non-separable wavelet is proposed in this paper. Firstly, a bank of non-separable orthogonal wavelet filters is used to capture characteristics of the iris. Secondly, a method of Markov random fields is used to capture rotation invariant iris feature. Finally, two-class kernel Fisher classifiers are adopted for classification. Experimental results on public iris databases show that the proposed approach has a low error rate and achieves true rotation invariance. © 2010.

Fast pyrolysis oil fuel blend for marine vessels

The main driver for the investigation of fast pyrolysis oil marine fuel blends is EU directive 2012/33/EU which aims to cut the sulphur content of marine fuel and thereby reduce air pollution caused by marine vessels. The aim of this study was to investigate the miscibility of 3- and 4- component blends containing pyrolysis oil, 1-butanol, biodiesel (RME) and/or marine gas oil (MGO). The ideal blend would be a stable homogenous product with a minimum amount of butanol, whilst maximising the amount of pyrolysis oil. A successful blend would have properties suitable for use in marine engines. In order to successfully utilise a marine fuel blend in commercial vessels it should meet minimum specification requirements such as a flash point ≥60°C. Blends of pyrolysis oil, RME, MGO and 1-butanol were evaluated and characterised. The mixed blends were inspected after 48 hours for homogeneity and the results plotted on a tri-plot phase diagram. Homogenous samples were tested for water content, pH, acid number, viscosity and flash point as these give indicate a blend’s suitability for engine testing. The work forms part of the ReShip Project which is funded by Norwegian industry partners and the Research Council of Norway (The ENERGIX programme).