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排序方式: 共有453条查询结果,搜索用时 281 毫秒
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Aziz S. Mousas Angelos-Christos G. Anadiotis Georgios V. Lioudakis John P. Papanis Panagiotis K. Gkonis Dimitra I. Kaklamani Iakovos S. Venieris 《Wireless Personal Communications》2014,76(1):99-119
This paper presents an integrated security architecture for heterogeneous distributed systems. Based on the MPEG-21 standard data structures and the MPEG-M standard services, the proposed architecture provides a unified, fine-grained solution for protecting each information unit circulated in the system. In this context, a novel scheme for translating the access control rules, initially expressed by means of the standard MPEG-21 Rights Expression Language, into Ciphertext-Policy Attribute-Based Encryption access trees is introduced, thereby enabling offline authorization based on the users’ attributes, also encapsulated and certified using MPEG-21 licenses. The proposed framework provides a detailed approach in all the steps of the information protection process, from attribute acquisition to data encryption and decryption. 相似文献
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A straightforward size exclusion chromatography (SEC) method was developed and validated for the determination of total polivinylpyrrolidone (PVP) in ophthalmic solutions using the unusual combination of size exclusion chromatography (SEC), ultraviolet-visible detection and quantitation of an analyte peak that elutes in the total exclusion volume of the column. Samples of opthalmic solutions are diluted with water and injected onto a TSKgel G1000PW, 7.5 mm i.d. × 30 cm, 12 μm column at 50°C, with 80:20 0.1M sodium acetate-methanol mobile phase and UV detection at 220 nm. Validation was successful for a stability indicating pharmaceutical method, with parameters including specificity, accuracy, linearity, and precision within typical pharmaceutical acceptance criteria. A stress study with acid, base, peroxide, heat, and light indicates that there is no interference from drug, product, or excipients. 相似文献
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Matsoukas MT Zoumpoulakis P Tselios T 《Journal of chemical information and modeling》2011,51(9):2386-2397
Aliskiren is a nonpeptide antihypertensive drug that potently inhibits the human enzyme renin in vitro and in vivo. Many clinical trials have shown the efficacy of aliskiren to lower blood pressure in correlation with other antihypertensive agents. In this report, the conformational behavior of aliskiren is studied in water, trifluoroethanol, and dimethylformamide solutions by means of 2D-NMR spectroscopy and molecular dynamics simulations. The stereochemical characteristics of aliskiren in different solutions, in combination with the previously published crystal structure of the renin-aliskiren complex have been investigated. The aim of this study was to explore the conformational behavior of this first successful renin inhibitor in relation to its environment. In aqueous solution, aliskiren adapts a U-shape conformation, whereas in DMF, the molecule is basically endowed with an "extended" conformation, which has more similarities to the one bound to the receptor. 相似文献
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Klaus Nolte Alexandros Kaloxylos Kostas Tsagkaris Thomas Rosowski Makis Stamatelatos Aristi Galani Eckard Bogenfeld Panagis Magdalinos Jens Tiemann Jens Gebert Paul Arnold Dirk von Hugo Nancy Alonistioti Panagiotis Demestichas Wolfgang Koenig 《International Journal of Network Management》2011,21(5):360-383
Future mobile networks are expected to be complex heterogeneous systems. On the one hand this will enable users to take advantage of a number of different access technologies. On the other hand it will seriously affect network management procedures since more extensive operations and decisions will have to be dealt with. To tackle these challenges a number of new dynamic mechanisms need to be designed. It is imperative that certain network management tasks have to be performed without human intervention to reduce the OPEX costs and achieve faster responses in different events. To achieve this goal, the introduction of self‐x functionalities, combined with cognitive mechanisms and the ability to reconfigure network entities and terminals, is required. Moreover, the introduction of a new pilot channel needs to be considered to assist the terminals in selecting the most suitable radio access technology according to their requirements. We present the functional architecture of an evolved network that was designed in the context of the EU‐funded IP project ‘E3: End‐to‐End Efficiency’. This architecture aims to enhance existing procedures usually performed in traditional operation and maintenance systems (e.g. spectrum management, network planning, configuration actions). We explain the rationale of our design and provide specific examples to illustrate the role of the different functional entities and their interfaces. A considerable part of this architecture has recently been approved as a feasibility study by the ETSI Committee Reconfigurable Radio System. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Which, if any, hydrates will crystallise? Predicting hydrate formation of two dihydroxybenzoic acids
Braun DE Karamertzanis PG Price SL 《Chemical communications (Cambridge, England)》2011,47(19):5443-5445
A study of two dihydroxybenzoic acid isomers shows that computational methods can be used to predict hydrate formation, the compound:water ratio and hydrate crystal structures. The calculations also help identify a novel hydrate found in the solid form screening that validates this study. 相似文献
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We fabricated a TiO(2)-ZrO(2) affinity chromatography micro-column on 2 mm PMMA plates, and demonstrated the enrichment and separation of (a) a standard mono- and tetra-phosphopeptide, and (b) phosphopeptides contained in a tryptic digest of β-Casein. The chromatography column consisted of 32 parallel microchannels with common input and output ports and was fabricated by lithography directly on the polymeric substrate followed by plasma etching (i.e. standard MEMS processing) and sealed with lamination. The liquid deposited TiO(2)-ZrO(2) stationary phase was characterized by X-ray diffraction and was found to be mostly TiO(2) and ZrO(2) in crystalline phases. Off-chip UV detection and MALDI MS identification of the separated effluents were used. The chip had a capacity of >1.4 μg (0.7 nmol) of a prototype mono-phosphopeptide and a recovery of 94 ± 3%, and can be used with small samples (less than 0.1 μL depending on the syringe pump used). The chip design allows an expansion of its capacity by means of increasing the number of parallel microchannels at a constant sample volume. Our approach provided an alternative to off-line extraction tips (with typical capacities of 1-2 μg and sample volumes of 1-10 μL), and to on-chip efforts based on packed bed and frit formats. 相似文献
40.
The stability of equilibrium and the possibility of generation of business cycles in a discrete interregional Kaldorian macrodynamic model with fixed exchange rates are explored using numerical methods. One of the aims is to illustrate the feasibility and effectiveness of the numerical approach for dynamical systems of moderately high dimensionality and several parameters. The model considered is five-dimensional with four parameters, the speeds of adjustment of the goods markets and the degrees of economic interactions between the regions through trade and capital movement. Using a grid search method for the determination of the region of stability of equilibrium in two-dimensional parameter subspaces, and coefficient criteria for the flip bifurcation - and Hopf bifurcation - curve, we determine the stability region in several parameter ranges and identify Hopf bifurcation curves when they exist. It is found that interregional cycles emerge only for sufficient interregional trade. The relevant threshold is predicted by the model at 14 - 16 % of trade transactions. By contrast, no minimum level of capital mobility exists in a global sense as a requirement for the emergence of interregional cycles; the main conclusion being, therefore, that cycles may occur for very low levels of capital mobility if trade is sufficient. Examples of bifurcation and Lyapunov exponent diagrams illustrating the occurrence of cycles or period doubling, and examples of the development of the occurring cycles, are given. Both supercritical and subcritical bifurcations are found to occur, the latter type indicating coexistence of a point and a cyclical attractor. 相似文献