5,005 research outputs found
Model Checking Access Control Policies: A Case Study using Google Cloud IAM
Authoring access control policies is challenging and prone to
misconfigurations. Access control policies must be conflict-free. Hence,
administrators should identify discrepancies between policy specifications and
their intended function to avoid violating security principles. This paper aims
to demonstrate how to formally verify access control policies. Model checking
is used to verify access control properties against policies supported by an
access control model. The authors consider Google's Cloud Identity and Access
Management (IAM) as a case study and follow NIST's guidelines to verify access
control policies automatically. Automated verification using model checking can
serve as a valuable tool and assist administrators in assessing the correctness
of access control policies. This enables checking violations against security
principles and performing security assessments of policies for compliance
purposes. The authors demonstrate how to define Google's IAM underlying
role-based access control (RBAC) model, specify its supported policies, and
formally verify a set of properties through three examples
Verification of Resilience Policies that Assist Attribute Based Access Control
Access control offers mechanisms to control and limit the actions or operations that are performed by a user on a set of resources in a system. Many access control models exist that are able to support this basic requirement. One of the properties examined in the context of these models is their ability to successfully restrict access to resources. Nevertheless, considering only restriction of access may not be enough in some environments, as in critical infrastructures. The protection of systems in this type of environment requires a new line of enquiry. It is essential to ensure that appropriate access is always possible, even when users and resources are subjected to challenges of various sorts. Resilience in access control is conceived as the ability of a system not to restrict but rather to ensure access to resources. In order to demonstrate the application of resilience in access control, we formally define an attribute based access control model (ABAC) based on guidelines provided by the National Institute of Standards and Technology (NIST). We examine how ABAC-based resilience policies can be specified in temporal logic and how these can be formally verified. The verification of resilience is done using an automated model checking technique, which eventually may lead to reducing the overall complexity required for the verification of resilience policies and serve as a valuable tool for administrators
Genetic engineering of plants through manipulation of lignin biosynthesis
The invention pertains to the genetically down regulating a lignin pathway p-coumarate Co-enzyme A ligase (CCL) in trees.https://digitalcommons.mtu.edu/patents/1044/thumbnail.jp
Methods of modifying lignin in plants by transformation with a 4-coumarate coenzyme a ligase nucleic acid
The invention pertains to methods of altering growth, lignin content, coniferyl and sinapyl alcohol units in the lignin structure, disease resistance and cellulose content in plants by transformation with a lignin pathway p-coumarate Co-enzyme A ligase (4CL) nucleic acid.https://digitalcommons.mtu.edu/patents/1058/thumbnail.jp
4-Coumarate co-enzyme a ligase promoter
The present invention provides a Populus 4-coumarate Co-enzyme A ligase gene promoter that directs expression in the xylem of plants. The promoter is used in methods designed to alter lignin content, lignin structure, cellulose content and combinations thereof. The methods comprise operably linking said promoter to heterologous nucleic acid molecules.https://digitalcommons.mtu.edu/patents/1051/thumbnail.jp
Formation of octapod MnO nanoparticles with enhanced magnetic properties through kinetically-controlled thermal decomposition of polynuclear manganese complexes
Polynuclear manganese complexes are used as precursors for the synthesis of manganese oxide nanoparticles (MnO NPs). Altering the thermal decomposition conditions can shift the nanoparticle product from spherical, thermodynamically-driven NPs to unusual, kinetically-controlled octapod structures. The resulting increased surface area profoundly alters the NP's surface-dependent magnetism and may have applications in nanomedicine
Mid-IR heterogeneous silicon photonics
In this paper we discuss silicon-based photonic integrated circuit technology for applications beyond the telecommunication wavelength range. Silicon-on-insulator and germanium-on-silicon passive waveguide circuits are described, as well as the integration of III-V semiconductors, IV-VI colloidal nanoparticle films and GeSn alloys on these circuits for increasing the functionality. The strong nonlinearity of silicon combined with the low nonlinear absorption in the mid-infrared is exploited to generate picosecond pulse based supercontinuum sources and optical parametric oscillators that can be used as spectroscopic sensor sources
Simulating hot Abelian gauge dynamics
The time evolution of soft modes in a quantum gauge field theory is to first
approximation classical, but the equations of motion are non-local. We show how
they can be written in a local and Hamiltonian way in an Abelian theory, and
that this formulation is particularly suitable for numerical simulations. This
makes it possible to simulate numerically non-equilibrium processes such as the
phase transition in the Abelian Higgs model and and to study, for instance,
bubble nucleation and defect formation. Such simulations would also help to
understand phase transitions in more complicated gauge theories. Moreover, we
show that the existing analytical results for the time-evolution in a
pure-gauge theory correspond to a special class of initial conditions and that
different initial conditions can lead to qualitatively different behavior. We
compare the results of the simulations to analytical calculations and find an
excellent agreement.Comment: 18 pages, 5 figures, REVTe
Tuning the Magnetic Anisotropy at a Molecule-Metal Interface
International audienceWe demonstrate that a C 60 overlayer enhances the perpendicular magnetic anisotropy of a Co thin film, inducing an inverse spin reorientation transition from in plane to out of plane. The driving force is the C 60 =Co interfacial magnetic anisotropy that we have measured quantitatively in situ as a function of the C 60 coverage. Comparison with state-of-the-art ab initio calculations show that this interfacial anisotropy mainly arises from the local hybridization between C 60 p z and Co d z 2 orbitals. By generalizing these arguments, we also demonstrate that the hybridization of C 60 with a Fe(110) surface decreases the perpendicular magnetic anisotropy. These results open the way to tailor the interfacial magnetic anisotropy in organic-material–ferromagnet systems
- …