49,737 research outputs found
Self-Adaptive Role-Based Access Control for Business Processes
© 2017 IEEE. We present an approach for dynamically reconfiguring the role-based access control (RBAC) of information systems running business processes, to protect them against insider threats. The new approach uses business process execution traces and stochastic model checking to establish confidence intervals for key measurable attributes of user behaviour, and thus to identify and adaptively demote users who misuse their access permissions maliciously or accidentally. We implemented and evaluated the approach and its policy specification formalism for a real IT support business process, showing their ability to express and apply a broad range of self-adaptive RBAC policies
Unstable and elusive superconductors
We briefly review earlier and report original experimental results in the
context of metastable or possible superconducting materials. We show that
applied electric field induces conducting state in Copper Chloride (CuCl) whose
characteristics resemble behavior of sliding charge-density-wave(s) (CDW). We
discuss whether the sliding CDW or collective transport of similar ordered
charge phase(s) may account for the problem of "high-temperature
superconductivity" observed in this and other materials, including Cadmium
Sulfide (CdS), metal-ammonia solutions, polymers, amorphous carbon and tungsten
oxides. We also discuss a local superconductivity that occurs at the surface of
graphite and amorphous carbon under deposition of foreign atoms/molecules.Comment: Invited review article published in a special edition on
Superconducting Materials in honor of the 95th birthday year of Ted Geballe,
edited by M. B. Maple, J. Hirsch, and F. Marsigli
Dressing a Naked Singularity: an Example
Considering the evolution of a perfect fluid with self-similarity of the
second kind, we have found that an initial naked singularity can be trapped by
an event horizon due to collapsing matter. The fluid moves along time-like
geodesics with a self-similar parameter . Since the metric
obtained is not asymptotically flat, we match the spacetime of the fluid with a
Schwarzschild spacetime. All the energy conditions are fulfilled until the
naked singularity.Comment: 14 pages, 1 figure. This version corrects an error in the calculus of
the pressure and in the conclusion
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