619 research outputs found
Covert Channels in SIP for VoIP signalling
In this paper, we evaluate available steganographic techniques for SIP
(Session Initiation Protocol) that can be used for creating covert channels
during signaling phase of VoIP (Voice over IP) call. Apart from characterizing
existing steganographic methods we provide new insights by introducing new
techniques. We also estimate amount of data that can be transferred in
signalling messages for typical IP telephony call.Comment: 8 pages, 4 figure
Repression of DNA-binding dependent glucocorticoid receptor-mediated gene expression
The glucocorticoid receptor (GR) affects the transcription of genes involved in diverse processes, including energy metabolism and the immune response, through DNA-binding dependent and independent mechanisms. The DNA-binding dependent mechanism occurs by direct binding of GR to glucocorticoid response elements (GREs) at regulatory regions of target genes. The DNA-binding independent mechanism involves binding of GR to transcription factors and coactivators that, in turn, contact DNA. A small molecule that competes with GR for binding to GREs could be expected to affect the DNA-dependent pathway selectively by interfering with the protein-DNA interface. We show that a DNA-binding polyamide that targets the consensus GRE sequence binds the glucocorticoid-induced zipper (GILZ) GRE, inhibits expression of GILZ and several other known GR target genes, and reduces GR occupancy at the GILZ promoter. Genome-wide expression analysis of the effects of this polyamide on a set of glucocorticoid-induced and -repressed genes could help to elucidate the mechanism of GR regulation for these genes
Horizon formation and far-from-equilibrium isotropization in supersymmetric Yang-Mills plasma
Using gauge/gravity duality, we study the creation and evolution of
anisotropic, homogeneous strongly coupled supersymmetric
Yang-Mills plasma. In the dual gravitational description, this corresponds to
horizon formation in a geometry driven to be anisotropic by a time-dependent
change in boundary conditions.Comment: 4 pages, typos corrected, published versio
Common Representation of Information Flows for Dynamic Coalitions
We propose a formal foundation for reasoning about access control policies
within a Dynamic Coalition, defining an abstraction over existing access
control models and providing mechanisms for translation of those models into
information-flow domain. The abstracted information-flow domain model, called a
Common Representation, can then be used for defining a way to control the
evolution of Dynamic Coalitions with respect to information flow
Extreme Makeover: Bending the Rules to Reduce Risk Rewriting Complex Systems
Abstract. We describe our experience using XP to reimplement sophisticated, high-performance imaging software in a research environment. We focus espe-cially on practices we used to derive value from the existing software, notably reimplementation by ransacking and conversion as learning. Our experience suggests that some of the classic 12 practices which define XP should be ad-justed when there is a existing, well-structured system to serve as a guide.
Chromosomes. CENP-C reshapes and stabilizes CENP-A nucleosomes at the centromere
Inheritance of each chromosome depends upon its centromere. A histone H3 variant, centromere protein A (CENP-A), is essential for epigenetically marking centromere location. We find that CENP-A is quantitatively retained at the centromere upon which it is initially assembled. CENP-C binds to CENP-A nucleosomes and is a prime candidate to stabilize centromeric chromatin. Using purified components, we find that CENP-C reshapes the octameric histone core of CENP-A nucleosomes, rigidifies both surface and internal nucleosome structure, and modulates terminal DNA to match the loose wrap that is found on native CENP-A nucleosomes at functional human centromeres. Thus, CENP-C affects nucleosome shape and dynamics in a manner analogous to allosteric regulation of enzymes. CENP-C depletion leads to rapid removal of CENP-A from centromeres, indicating their collaboration in maintaining centromere identity.NIH grants: (GM082989, CA186430, GM008275, GM008216, GM007229); American Heart Association predoctoral fellowship; American Cancer Society postdoctoral fellowship; NSF grant: (agreement DMR-0944772)
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