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41.
J EL GHOUL 《Bulletin of Materials Science》2016,39(1):7-12
The synthesis by the sol–gel method, structural and optical properties of ZnO, Zn0.99Al0.01O (AlZ), Zn0.9V0.1O (VZ) and Zn0.89Al0.01V0.1O (AlVZ) nanoparticles was reported. The approach was slow release of water for hydrolysis by esterification reaction followed by a supercritical drying in ethyl alcohol. After thermal treatment at 500°C in air, the obtained nanopowders were characterized by various techniques such as transmission electron microscopy, X-ray diffraction and photoluminescence (PL) spectroscopy. The structural properties showed that the ZnO nanoparticles with an average particle size of 25 nm exhibit hexagonal wurtzite structure. From the optical studies, it was found that the optical band gap was located between 2.97 and 3.17 eV. The obtained electrical properties showed the potential application of the samples in optoelectronic devices. The powder of AlVZ presented a strong luminescence band in the visible range. The PL band energy position presented a small blue shift with the increase of measurement temperature. Different possible attributions of this emission band will be discussed. 相似文献
42.
A high-accuracy cryogenic radiometer has been developed at the National Institute of Standards and Technology to serve as a primary standard for optical power measurements. This instrument is an electrical-substitution radiometer that can be operated at cryogenic temperatures to achieve a relative standard uncertainty of 0.021% at an optical power level of 0.8 mW. The construction and operation of the high-accuracy cryogenic radiometer and the uncertainties in optical power measurements are detailed. 相似文献
43.
EL Brandwene SR Williams C Tunget-Johnson SG Turchen AS Manoguerra RF Clark 《Canadian Metallurgical Quarterly》1996,14(6):691-695
Treatment of an acetaminophen overdose with N-acetyl cysteine usually is based on the position of the 4-h acetaminophen (APAP) level on the Rumack-Matthew nomogram; however, there is disagreement on the level at which clinically relevant hepatotoxicity occurs. A retrospective review of all acute adult formulation APAP exposures reported to our poison center between 1986 and 1993 was performed and cases corresponding to the "possible risk or toxicity" range on the nomogram were identified. Our current poison center protocol for APAP poisoning does not recommend treatment with N-acetylcysteine (NAC) in low-risk patients if the 4-h serum APAP level or the extrapolated equivalent falls within the possible toxicity range on the nomogram. Seventeen cases met the inclusion criteria for the study and received no NAC; six additional patients met inclusion criteria but received one or two doses of NAC before therapy was discontinued. No patients in either group demonstrated clinical evidence of hepatotoxicity. This pilot study suggests that patients with no risk factors and APAP levels in the "possible risk" range may not require NAC therapy. 相似文献
44.
Hany F. EL Yamany Miriam A.M. Capretz David S. Allison 《Information and Software Technology》2010,52(2):220-236
One of the most significant difficulties with developing Service-Oriented Architecture (SOA) involves meeting its security challenges, since the responsibilities of SOA security are based on both the service providers and the consumers. In recent years, many solutions to these challenges have been implemented, such as the Web Services Security Standards, including WS-Security and WS-Policy. However, those standards are insufficient for the new generation of Web technologies, including Web 2.0 applications. In this research, we propose an intelligent SOA security framework by introducing its two most promising services: the Authentication and Security Service (NSS), and the Authorization Service (AS). The suggested autonomic and reusable services are constructed as an extension of WS-1 security standards, with the addition of intelligent mining techniques, in order to improve performance and effectiveness. In this research, we apply three different mining techniques: the Association Rules, which helps to predict attacks, the Online Analytical Processing (OLAP) Cube, for authorization, and clustering mining algorithms, which facilitate access control rights representation and automation. Furthermore, a case study is explored to depict the behavior of the proposed services inside an SOA business environment. We believe that this work is a significant step towards achieving dynamic SOA security that automatically controls the access to new versions of Web applications, including analyzing and dropping suspicious SOAP messages and automatically managing authorization roles. 相似文献
45.
Lee B Parr CS Plaisant C Bederson BB Veksler VD Gray WD Kotfila C 《IEEE transactions on visualization and computer graphics》2006,12(6):1414-1426
Despite extensive research, it is still difficult to produce effective interactive layouts for large graphs. Dense layout and occlusion make food Webs, ontologies and social networks difficult to understand and interact with. We propose a new interactive visual analytics component called TreePlus that is based on a tree-style layout. TreePlus reveals the missing graph structure with visualization and interaction while maintaining good readability. To support exploration of the local structure of the graph and gathering of information from the extensive reading of labels, we use a guiding metaphor of "plant a seed and watch it grow." It allows users to start with a node and expand the graph as needed, which complements the classic overview techniques that can be effective at (but often limited to) revealing clusters. We describe our design goals, describe the interface and report on a controlled user study with 28 participants comparing TreePlus with a traditional graph interface for six tasks. In general, the advantage of TreePlus over the traditional interface increased as the density of the displayed data increased. Participants also reported higher levels of confidence in their answers with TreePlus and most of them preferred TreePlus 相似文献
46.
EL Wallace DM Surgenor HS Hao J An RH Chapman WH Churchill 《Canadian Metallurgical Quarterly》1993,33(2):139-144
A poor response to L-DOPA in addition to parkinsonian, cerebellar, and autonomic signs is commonly regarded as indicative of clinical multiple system atrophy (MSA). We compared the motor response to a single oral administration of 250 mg L-DOPA/25 mg carbidopa in eight MSA patients and eight Parkinson's disease (PD) patients with the "on-off" phenomenon, evaluating L-DOPA peripheral pharmacokinetics. Motor response was consistently good in all PD patients, but only four MSA patients had a (moderate) response. Pharmacokinetic parameters did not differ between the groups. The varying extent of putaminal damage could be responsible for the differing motor response to L-DOPA in MSA patients. 相似文献
47.
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49.
John B. Parr 《The Annals of Regional Science》2012,49(2):293-303
The total population and the overall average density are derived for a single city, in which the spatial structure conforms approximately to the negative exponential function. It is then shown that across the cities of an urban system, the areal extent of a city is positively related to its average density and also to its population. Consideration is next given to a system of regions and again to the manner in which areal extent is related to average density and population across regions. In this setting, however, the relationships are usually different from those found within an urban system. 相似文献
50.
Luenberger observer theory is extended to distributed parameter systems. This extension is based on the consideration of sensors. For systems with infinite dimensional state spaces, it is possible to construct the state vector asymptotically (or a part of the state vector) by a ‘good’ choice of sensors. We show that the link between detectability and sensor structure may be of some interest in the construction of observers. 相似文献