318 research outputs found
A Special Class of Rank 10 and 11 Coxeter Groups
In the course of investigating regular subalgebras of E(10) related to
cosmological solutions of 11-dimensional supergravity supporting an electric
4-form field, a class of rank 10 Coxeter subgroups of the Weyl group of E(10)
was uncovered (hep-th/0606123). These Coxeter groups all share the property
that their Coxeter graphs have incidence index 3, i.e. that each node is
incident to three and only three single lines. Furthermore, the Coxeter
exponents are either 2 or 3, but never infinity. We here go beyond subgroups of
the Weyl group of E(10) and classify all rank 10 Coxeter groups with these
properties. We find 21 distinct Coxeter groups of which 7 were already
described in hep-th/0606123. Moreover, we extend the classification to the rank
11 case and we find 252 inequivalent rank 11 Coxeter groups with incidence
index 4, of which at least 28 can be regularly embedded into E(11).Comment: 20 pages, Typos corrected, Erratum added correcting the total number
of rank 11 Coxeter graphs with incidence index
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Bloodhound: Searching Out Malicious Input in Network Flows for Automatic Repair Validation
Many current systems security research efforts focus on mechanisms for Intrusion Prevention and Self-Healing Software. Unfortunately, such systems find it difficult to gain traction in many deployment scenarios. For self-healing techniques to be realistically employed, system owners and administrators must have enough confidence in the quality of a generated fix that they are willing to allow its automatic deployment. In order to increase the level of confidence in these systems, the efficacy of a 'fix' must be tested and validated after it has been automatically developed, but before it is actually deployed. Due to the nature of attacks, such verification must proceed automatically. We call this problem Automatic Repair Validation (ARV). As a way to illustrate the difficulties faced by ARV, we propose the design of a system, Bloodhound, that tracks and stores malicious network flows for later replay in the validation phase for self-healing softwar
Bloodhound: Searching Out Malicious Input in Network Flows for Automatic Repair Validation
Many current systems security research efforts focus on mechanisms for Intrusion Prevention and Self-Healing Software. Unfortunately, such systems find it difficult to gain traction in many deployment scenarios. For self-healing techniques to be realistically employed, system owners and administrators must have enough confidence in the quality of a generated fix that they are willing to allow its automatic deployment. In order to increase the level of confidence in these systems, the efficacy of a 'fix' must be tested and validated after it has been automatically developed, but before it is actually deployed. Due to the nature of attacks, such verification must proceed automatically. We call this problem Automatic Repair Validation (ARV). As a way to illustrate the difficulties faced by ARV, we propose the design of a system, Bloodhound, that tracks and stores malicious network flows for later replay in the validation phase for self-healing softwar
Three-dimensional black holes from deformed anti-de Sitter
We present new exact three-dimensional black-string backgrounds, which
contain both NS--NS and electromagnetic fields, and generalize the BTZ black
holes and the black string studied by Horne and Horowitz. They are obtained as
deformations of the Sl(2,R) WZW model. Black holes resulting from purely
continuous deformations possess true curvature singularities. When discrete
identifications are introduced, extra chronological singularities appear, which
under certain circumstances turn out to be naked. The backgrounds at hand
appear in the moduli space of the Sl(2,R) WZW model. Hence, they provide exact
string backgrounds and allow for a more algebraical CFT description. This makes
possible the determination of the spectrum of primaries.Comment: JHEP style, 33 pages, 1 figur
Novel Branches of (0,2) Theories
We show that recently proposed linear sigma models with torsion can be
obtained from unconventional branches of conventional gauge theories. This
observation puts models with log interactions on firm footing. If non-anomalous
multiplets are integrated out, the resulting low-energy theory involves log
interactions of neutral fields. For these cases, we find a sigma model geometry
which is both non-toric and includes brane sources. These are heterotic sigma
models with branes. Surprisingly, there are massive models with compact complex
non-Kahler target spaces, which include brane/anti-brane sources. The simplest
conformal models describe wrapped heterotic NS5-branes. We present examples of
both types.Comment: 36 pages, LaTeX, 2 figures; typo in Appendix fixed; references added
and additional minor change
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Online Network Forensics for Automatic Repair Validation
Automated intrusion prevention and self-healing software are active areas of security systems research. A major hurdle for the widespread deployment of these systems is that many system administrators lack confidence in the quality of the generated fixes. Thus, a key requirement for future self-healing software is that each automatically-generated fix must be validated before deployment. Under the response rates required by self-healing systems, we believe such verification must proceed automatically. We call this process Automatic Repair Validation (ARV). We describe the design and implementation of Bloodhound, a system that tags and tracks information between the kernel and the application and correlates symptoms of exploits (such as memory errors) with high-level data (e.g., network flows). By doing so, Bloodhound can replay the flows that triggered the repair process against the newly healed application to help show that the repair is accurate (i.e., it defeats the exploit). We show through experimentation a performance impact of as little as 2.6%
Optimizing Two-Color Semiconductor Nanocrystal Immunoassays in Single Well Microtiter Plate Formats
The simultaneous detection of two analytes, chicken IgY (IgG) and Staphylococcal enterotoxin B (SEB), in the single well of a 96-well plate is demonstrated using luminescent semiconductor quantum dot nanocrystal (NC) tracers. The NC-labeled antibodies were prepared via sulfhydryl-reactive chemistry using a facile protocol that took <3 h. Dose response curves for each target were evaluated in a single immunoassay format and compared to Cy5, a fluorophore commonly used in fluorescent immunoassays, and found to be equivalent. Immunoassays were then performed in a duplex format, demonstrating multiplex detection in a single well with limits of detection equivalent to the single assay format: 9.8 ng/mL chicken IgG and 7.8 ng/mL SEB
A Cosmological Model of Thermodynamic Open Universe
In this paper we have given a generalisation of the earlier work by Prigogine
et al. who have constructed a phenomenological model of entropy production via
particle creation in the very early universe generated out of the vacuum rather
than from a singularity, by including radiation also as the energy source and
tried to develop an alternative cosmological model in which particle creation
prevents the big bang. We developed Radiation dominated model of the universe
which shows a general tendency that (i) it originates from instability of
vacuum rather than from a singularity. (ii) Up to a characteristic time
cosmological quantities like density, pressure, Hubble constant and expansion
parameter vary rapidly with time. (iii) After the characteristic time these
quantities settles down and the models are turned into de-sitter type model
with uniform matter, radiation, creation densities and Hubble's constant H. The
de-sitter regime survives during a decay time then connects continuously to a
usual adiabatic matter radiation RW universe.The interesting thing in the paper
is that we have related the phenomenological radiation dominated model to
macroscopic model of quantum particle creation in the early universe giving
rise to the present observed value of cosmic background radiation . It is also
found that the dust filled model tallies exactly with that of the Prigogine's
one, which justifies that our model is generalized Prigogine's model. Although
the model originates from instability of vacuum rather than from a singularity,
still there is a couple of unavoidable singularities in the model.Comment: 10,Accepted for publication in International journal of theoretical
physics,doi:10.1007/s10773-012-1142-
The hidden horizon and black hole unitarity
We motivate through a detailed analysis of the Hawking radiation in a
Schwarzschild background a scheme in accordance with quantum unitarity. In this
scheme the semi-classical approximation of the unitary quantum - horizonless -
black hole S-matrix leads to the conventional description of the Hawking
radiation from a classical black hole endowed with an event horizon. Unitarity
is borne out by the detailed exclusive S-matrix amplitudes. There, the fixing
of generic out-states, in addition to the in-state, yields in asymptotic
Minkowski space-time saddle-point contributions which are dominated by
Planckian metric fluctuations when approaching the Schwarzschild radius. We
argue that these prevent the corresponding macroscopic "exclusive backgrounds"
to develop an event horizon. However, if no out-state is selected, a distinct
saddle-point geometry can be defined, in which Planckian fluctuations are
tamed. Such "inclusive background" presents an event horizon and constitutes a
coarse-grained average over the aforementioned exclusive ones. The classical
event horizon appears as a coarse-grained structure, sustaining the
thermodynamic significance of the Bekenstein-Hawking entropy. This is
reminiscent of the tentative fuzzball description of extremal black holes: the
role of microstates is played here by a complete set of out-states. Although
the computations of unitary amplitudes would require a detailed theory of
quantum gravity, the proposed scheme itself, which appeals to the metric
description of gravity only in the vicinity of stationary points, does not.Comment: 29 pages, 4 figures. Typos corrected. Two footnotes added (footnotes
3 and 5
Large N=4 Holography
The class of 2d minimal model CFTs with higher spin AdS3 duals is extended to
theories with large N=4 superconformal symmetry. We construct a higher spin
theory based on the global D(2,1|alpha) superalgebra, and propose a large N
family of cosets as a dual CFT description. We also indicate how a non-abelian
version of this Vasiliev higher spin theory might give an alternative
description of IIB string theory on an AdS3 x S3 x S3 x S1 background.Comment: 41 pages, LaTe
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