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21.
22.
In this paper the time-domain surface impedances of an homogeneous absorber layer, are given for the vertical and horizontal polarizations, or respectively for the electric field perpendicular or parallel to the incidence plane. It turns out that the application of the concept in finite difference time-domain (FDTD) in absorbing surface impedances boundary conditions, gives results in good agreement with analytical Fresnel reflection coefficients. 相似文献
23.
Cyberattacks are difficult to prevent because the targeted companies and organizations are often relying on new and fundamentally insecure cloud-based technologies, such as the Internet of Things. With increasing industry adoption and migration of traditional computing services to the cloud, one of the main challenges in cybersecurity is to provide mechanisms to secure these technologies. This work proposes a Data Security Framework for cloud computing services (CCS) that evaluates and improves CCS data security from a software engineering perspective by evaluating the levels of security within the cloud computing paradigm using engineering methods and techniques applied to CCS. This framework is developed by means of a methodology based on a heuristic theory that incorporates knowledge generated by existing works as well as the experience of their implementation. The paper presents the design details of the framework, which consists of three stages: identification of data security requirements, management of data security risks and evaluation of data security performance in CCS. 相似文献
24.
Alain Denise Marie-Claude Gaudel Sandrine-Dominique Gouraud Richard Lassaigne Johan Oudinet Sylvain Peyronnet 《International Journal on Software Tools for Technology Transfer (STTT)》2012,14(1):73-93
This paper presents several randomised algorithms for generating paths in large models according to a given coverage criterion.
Using methods for counting combinatorial structures, these algorithms can efficiently explore very large models, based on
a graphical representation by an automaton or by a product of several automata. This new approach can be applied to random
exploration in order to optimise path coverage and can be generalised to take into account other coverage criteria, via the
definition of a notion of randomised coverage satisfaction. Our main contributions are a method for drawing paths uniformly
at random in composed models, i.e. models that are given as products of automata, first without and then with synchronisation;
a new efficient approach to draw paths at random taking into account some other coverage criterion. Experimental results show
promising agreement with theoretical predictions and significant improvement over previous randomised approaches. This work
opens new perspectives for future studies of statistical testing and model checking, mainly to fight the combinatorial explosion
problem. 相似文献
25.
Before describing the mainFet modelings today available, the main technological evolutions ofMesfet andTegfet are summarized. It is brought some information on the various physical effects that occur in the devices and that must be taken into account in the models. It is shown that the different kinds of modelings (Monte Carlo, two dimensional, one dimensional) constitute a continuous chain, where the different elements appear strictly complementary. Finally, the present situation concerning modeling ofMesfet andTegfet will be presented. 相似文献
26.
Aleksandra Nijak Johan Saenen Alain J. Labro Dorien Schepers Bart L. Loeys Maaike Alaerts 《International journal of molecular sciences》2021,22(6)
Brugada syndrome (BrS) is an inherited cardiac arrhythmia that predisposes to ventricular fibrillation and sudden cardiac death. It originates from oligogenic alterations that affect cardiac ion channels or their accessory proteins. The main hurdle for the study of the functional effects of those variants is the need for a specific model that mimics the complex environment of human cardiomyocytes. Traditionally, animal models or transient heterologous expression systems are applied for electrophysiological investigations, each of these models having their limitations. The ability to create induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), providing a source of human patient-specific cells, offers new opportunities in the field of cardiac disease modelling. Contemporary iPSC-CMs constitute the best possible in vitro model to study complex cardiac arrhythmia syndromes such as BrS. To date, thirteen reports on iPSC-CM models for BrS have been published and with this review we provide an overview of the current findings, with a focus on the electrophysiological parameters. We also discuss the methods that are used for cell derivation and data acquisition. In the end, we critically evaluate the knowledge gained by the use of these iPSC-CM models and discuss challenges and future perspectives for iPSC-CMs in the study of BrS and other arrhythmias. 相似文献
27.
Yves Denizot Laurence Michel Jacques Benveniste Alain Meybeck Yolène Thomas Louis Duberfret 《Lipids》1991,26(12):1093-1094
Paf is a phospholipid mediator present in human skin which induces inflammatory events such as neutrophil infiltration and
increased vascular permeability. Recent data suggest that cutaneous cells, such as fibroblasts and keratinocytes, produce
paf and that paf is released during allergic cutaneous reactions. It is tempting to speculate that paf may contribute to the
development of various skin disorders with acute and chronic skin inflammation. Paf antagonists may help in bringing answers
to this hypothesis and may offer new prospects for the treatment of cutaneous inflammatory diseases.
Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl
Ether Lipids, Tokyo, Japan, May 1989. 相似文献
28.
Antoine T Priem B Heyraud A Greffe L Gilbert M Wakarchuk WW Lam JS Samain E 《Chembiochem : a European journal of chemical biology》2003,4(5):406-412
Two metabolically engineered Escherichia coli strains have been constructed to produce the carbohydrate moieties of gangliosides GM2 (GalNAcbeta-4(NeuAcalpha-3)Galbeta-4Glc; Gal = galactose, Glc = glucose, Ac = acetyl) and GM1 (Galbeta-3GalNAcbeta-4(NeuAcalpha-3)Galbeta-4Glc. The GM2 oligosaccharide-producing strain TA02 was devoid of both beta-galactosidase and sialic acid aldolase activities and overexpressed the genes for CMP-NeuAc synthase (CMP = cytidine monophosphate), alpha-2,3-sialyltransferase, UDP-GlcNAc (UDP = uridine diphosphate) C4 epimerase, and beta-1,4-GalNAc transferase. When this strain was cultivated on glycerol, exogenously added lactose and sialic acid were shown to be actively internalized into the cytoplasm and converted into GM2 oligosaccharide. The in vivo synthesis of GM1 oligosaccharide was achieved by taking a similar approach but using strain TA05, which additionally overexpressed the gene for beta-1,3-galactosyltransferase. In high-cell-density cultures, the production yields for the GM2 and GM1 oligosaccharides were 1.25 g L(-1) and 0.89 g L(-1), respectively. 相似文献
29.
The modification of the interface in immiscible polymer blends is critical in order to optimize physical properties. Despite the great commercial importance of polymer blends, many aspects of the emulsification process remain unclear In this paper, it will be shown that an emulsification curve can be used to estimate the influence of the architecture molar mass of styrene/hydrogenated butadiene block copolymer interfacial modifiers on the emulsifion of polystyrene/ethylene-propylene rubber blends under melt processing conditions. An expression for eing the critical amount of copolymer to saturate the interface, as well as aspects concerning the localisation of the modifier in the blend system will also be addressed. 相似文献
30.
Topics in Catalysis - This Synthetic Gas Bench (SGB) study focuses on the effect of cell geometry and wall thickness on the gasoline NO x trap functionality. The data show that besides a NO x trap... 相似文献