36 research outputs found

    CA-ARBAC: privacy preserving using context-aware role-based access control on Android permission system

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    Existing mobile platforms are based on manual way of granting and revoking permissions to applications. Once the user grants a given permission to an application, the application can use it without limit, unless the user manually revokes the permission. This has become the reason for many privacy problems because of the fact that a permission that is harmless at some occasion may be very dangerous at another condition. One of the promising solutions for this problem is context-aware access control at permission level that allows dynamic granting and denying of permissions based on some predefined context. However, dealing with policy configuration at permission level becomes very complex for the user as the number of policies to configure will become very large. For instance, if there are A applications, P permissions, and C contexts, the user may have to deal with A × P × C number of policy configurations. Therefore, we propose a context-aware role-based access control model that can provide dynamic permission granting and revoking while keeping the number of policies as small as possible. Although our model can be used for all mobile platforms, we use Android platform to demonstrate our system. In our model, Android applications are assigned roles where roles contain a set of permissions and contexts are associated with permissions. Permissions are activated and deactivated for the containing role based on the associated contexts. Our approach is unique in that our system associates contexts with permissions as opposed to existing similar works that associate contexts with roles. As a proof of concept, we have developed a prototype application called context-aware Android role-based access control. We have also performed various tests using our application, and the result shows that our model is working as desired

    Unveiling Inherent Degeneracies in Determining Population-Weighted Ensembles of Interdomain Orientational Distributions Using NMR Residual Dipolar Couplings: Application to RNA Helix Junction Helix Motifs

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    A growing number of studies employ time-averaged experimental data to determine dynamic ensembles of biomolecules. While it is well-known that different ensembles can satisfy experimental data to within error, the extent and nature of these degeneracies, and their impact on the accuracy of the ensemble determination remains poorly understood. Here, we use simulations and a recently introduced metric for assessing ensemble similarity to explore degeneracies in determining ensembles using NMR residual dipolar couplings (RDCs) with specific application to A-form helices in RNA. Various target ensembles were constructed representing different domain–domain orientational distributions that are confined to a topologically restricted (<10%) conformational space. Five independent sets of ensemble averaged RDCs were then computed for each target ensemble and a “sample and select” scheme used to identify degenerate ensembles that satisfy RDCs to within experimental uncertainty. We find that ensembles with different ensemble sizes and that can differ significantly from the target ensemble (by as much as ∑Ω ∼ 0.4 where ∑Ω varies between 0 and 1 for maximum and minimum ensemble similarity, respectively) can satisfy the ensemble averaged RDCs. These deviations increase with the number of unique conformers and breadth of the target distribution, and result in significant uncertainty in determining conformational entropy (as large as 5 kcal/mol at <i>T</i> = 298 K). Nevertheless, the RDC-degenerate ensembles are biased toward populated regions of the target ensemble, and capture other essential features of the distribution, including the shape. Our results identify ensemble size as a major source of uncertainty in determining ensembles and suggest that NMR interactions such as RDCs and spin relaxation, on their own, do not carry the necessary information needed to determine conformational entropy at a useful level of precision. The framework introduced here provides a general approach for exploring degeneracies in ensemble determination for different types of experimental data

    Ownership reform and the changing manufacturing landscape in Chinese cities: The case of Wuxi

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    <div><p>Since the economic transition, manufacturing in China has undergone profound changes not only in number of enterprises, but also in ownership structure and intra-urban spatial distribution. Investigating the changing manufacturing landscape from the perspective of ownership structure is critical to a deep understanding of the changing role of market and government in re-shaping manufacturing location behavior. Through a case study of Wuxi, a city experiencing comprehensive ownership reform, this paper presents a detailed analysis of the intra-urban spatial shift of manufacturing, identifies the location discrepancies, and examines the underlying forces responsible for the geographical differentiations. Through zone- and district-based analysis, a distinctive trend of decentralization and suburbanization, as well as an uneven distribution of manufacturing, is unveiled. The results of Location Quotient analysis show that the distribution of manufacturing by ownership exhibits distinctive spatial patterns, which is characterized by a historically-based, market-led, and institutionally-created spatial variation. By employing Hot Spot analysis, the role of development zones in attracting manufacturing enterprises of different ownerships is established. Overall, the location behavior of the diversified manufacturing has been increasingly based on the forces of market since the land marketization began. A proactive role played by local governments has also guided the enterprise location decision through spatial planning and regulatory policies.</p></div

    National-level and provincial-level development zone in Wuxi, 2013.

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    <p>National-level and provincial-level development zone in Wuxi, 2013.</p

    Electrostatic Catalysis Induced by Luciferases in the Decomposition of the Firefly Dioxetanone and Its Analogue

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    The variations of the barrier heights in the decomposition of the firefly dioxetanone and its analogues with the electrostatic field produced by the active site amino acid residues in the firefly luciferase are examined by a density functional theory study of the high-energy intermediates of the three luciferins. The positive electric field along the long-axis direction of the luciferins lowers the activation energy and acts as an electrostatic catalyst in the thermolysis process. The calculated barrier heights for the firefly dioxetanone and its analogues surrounded by the firefly Photinus pyralis luciferase show that the energy barrier of the firefly dioxetanone is lowered by the luciferase but is raised for the other analogue. Thus, the thermolysis rate is enhanced for the natural d-luciferin and reduced for the other analogue by the firefly luciferase, which elucidates why the luciferase acts as a catalyst for the natural d-luciferin but makes some luciferins emit weaker light signals

    The evolution model of manufacturing landscape in Wuxi.

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    <p>The evolution model of manufacturing landscape in Wuxi.</p

    Spatial changes of manufacturing in Wuxi, 1985, 2004 and 2013.

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    <p>Spatial changes of manufacturing in Wuxi, 1985, 2004 and 2013.</p

    Location quotients for manufacturing enterprises by ownership in Wuxi, 1985, 2004 and 2013.

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    <p>Location quotients for manufacturing enterprises by ownership in Wuxi, 1985, 2004 and 2013.</p

    Changes of manufacturing enterprises by ownership, 1985, 2004 and 2013.

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    <p>Changes of manufacturing enterprises by ownership, 1985, 2004 and 2013.</p

    Hotspot analysis of output value of manufacturing enterprises by ownership in Wuxi, 2013 (Note: AE: All Enterprises; HIDZ: High-tech Industrial Development Zone; IP: Industrial Park; EPZ: Export Processing Zone; ETDZ: Economic and Technical Development Zone; NTRA: National Tourism Resort Area; EDZ: Economic Development Zone; PIP: Private Industrial Park; SIP: Supporting Industrial Park; ICP: Industrial Concentration Park; HIP: High-tech Industrial Park; ITP: International Technical Park).

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    <p>Hotspot analysis of output value of manufacturing enterprises by ownership in Wuxi, 2013 (Note: AE: All Enterprises; HIDZ: High-tech Industrial Development Zone; IP: Industrial Park; EPZ: Export Processing Zone; ETDZ: Economic and Technical Development Zone; NTRA: National Tourism Resort Area; EDZ: Economic Development Zone; PIP: Private Industrial Park; SIP: Supporting Industrial Park; ICP: Industrial Concentration Park; HIP: High-tech Industrial Park; ITP: International Technical Park).</p
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