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21.
Neurological complications arising from schistosomiasis are uncommon, and reports of Manson's schistosomiasis presenting as an intracerebral mass lesion are particularly rare. The authors describe the case of a 26-year-old man with a 3-month history of headaches and visual abnormalities. He had immigrated to Canada from Brazil 4 years previously. The patient's general physical and neurological examinations were unremarkable. Magnetic resonance (MR) imaging revealed an enhancing lesion with surrounding edema and mild mass effect in the right occipital lobe. A stereotactic brain biopsy demonstrated intraparenchymal granulomas surrounding Schistosoma masoni eggs. The patient's symptoms resolved following treatment with praziquantel and steroid medications; follow-up MR imaging yielded normal findings. This case demonstrates that neuroschistosomiasis should be considered when an individual presenting with an intracerebral mass has lived in a region in which this disease is endemic. 相似文献
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23.
Concepts for Groundwater Purification Contamination of water‐bearing strata is, in contrast to the contamination of surface waters, for most people not noticeable. However this does not lead, at least in Germany, to reduced awareness about the problem, as drinking water and groundwater are closely connected in the public’s mind. The cleanup of contaminated groundwater is generally aimed at a negligibly low or tolerable remaining risk for the subjects of the protection. The goals of the cleanup should always be considered in the light of the appropriateness of the time and effort involved and the environmental balance of cleanup measures. Otherwise there is the danger that technical environmental protection however well meant is directed against the environment, because the associated use of resources is greater than that for the protection or regeneration at which it is targeted. Different cleanup concepts are represented in the order of decreasing intensity of the technical measures. 相似文献
24.
S. M. Donovan J. D. Mackenzie C. R. Abernathy S. J. Pearton P. C. Chow J. Van Hove 《Journal of Electronic Materials》1997,26(11):1292-1296
The effects of growth temperature and nitrogen plasma biasing on the electrical and structural properties of InN grown using
electron cyclotron resonance metalorganic molecular beam epitaxy (ECR MOMBE) have been investigated. These results are compared
to those found from InN grown using a higher energy radio frequency (rf) plasma source (rf MOMBE). By varying the bias of
the nitrogen plasma or the growth temperature, it is possible to achieve smooth surface morphologies. However, biasing can
also be used to increase the mobility by a factor of two while the growth temperature has only a small effect. By contrast,
use of an rf plasma improves mobility by nearly a factor of ten. None of the growth conditions investigated were found to
significantly alter the electron concentration, which was measured to be 1−5 × 1020 cm−3. 相似文献
25.
A polytitanocarbosilane has been prepared from polycarbosilane and titanium n-butoxide.29Si MAS-NMR was used to characterize the various steps of the conversion process of the polymer into the final ceramic. The reaction of titanium butoxide with polycarbosilane introduces oxygen into the polymer that seems to play an important role in the pyrolysis process. In the first stage up to 1000 ° C, the study reveals the cleavage of Si-C bonds and the formation of SiC4-xOx units. In the second stage, above 1000 ° C, the number of Si-O bonds decreases, probably due to a carbothermal reduction process. At 1500 ° C, the product can be described as a mixture of crystalline SiC and TiC with no excess carbon. 相似文献
26.
Limit and shakedown analysis of nozzle/cylinder intersections under internal pressure and in-plane moment loading 总被引:7,自引:0,他引:7
C. Nadarajah D. Mackenzie J.T. Boyle 《International Journal of Pressure Vessels and Piping》1996,68(3):261-272
A simple technique called the elastic compensation method developed previously by Mackenzie & Boyle is used in combination with full three-dimensional finite-element analysis to obtain limit and shakedown interaction diagrams for nozzle/cylinder intersections subject to combined internal pressure and in-plane nozzle moment loading. The results are compared with solutions from the literature and also with detailed elasto-plastic thin shell finite-element analysis. It is found that the simple elastic compensation procedure can provide good estimates of plastic failure mechanisms for complex three-dimensional structures. A detailed discussion of various issues which arose relates to finite-element modelling and the measures taken to improve the results are also documented. 相似文献
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28.
Cognitive networks: adaptation and learning to achieve end-to-end performance objectives 总被引:11,自引:0,他引:11
Ryan W. Thomas Daniel H. Friend Luiz A. Dasilva Allen B. Mackenzie 《Communications Magazine, IEEE》2006,44(12):51-57
In this article we advance the idea of a cognitive network, capable of perceiving current network conditions and then planning, learning, and acting according to end-to-end goals. Cognitive networks are motivated by the complexity, heterogeneity, and reliability requirements of tomorrow's networks, which are increasingly expected to self-organize to meet user and application objectives. We compare and contrast cognitive networks with related research on cognitive radios and cross-layer design. By defining cognitive networks, examining their relationship to other technologies, discussing critical design issues, and providing a framework for implementation, we aim to establish a foundation for further research and discussion 相似文献
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30.
L. Hobbs I. Eddie G. Erwin A. C. Bryce R. M. De La Rue J. S. Roberts T. F. Krauss D. W. Mccomb M. Mackenzie 《Journal of Electronic Materials》2005,34(3):232-239
Annealing or processing of AlAs that has been subjected to a wet thermal oxidation process can result in severe delamination
of material at the oxidation front. This paper reports a procedure for preventing this delamination and presents a possible
cause for the delamination. 相似文献