2,142 research outputs found
Fusion algebras for imprimitive complex reflection groups
We prove that the Fourier matrices for the imprimitive complex reflection
groups introduced by Malle define fusion algebras with not necessarily positive
but integer structure constants. Hence they define Z-algebras. As a result, we
obtain that all known Fourier matrices belonging to spetses define algebras
with integer structure constants.Comment: 14 page
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Dual gene activation and knockout screen reveals directional dependencies in genetic networks.
Understanding the direction of information flow is essential for characterizing how genetic networks affect phenotypes. However, methods to find genetic interactions largely fail to reveal directional dependencies. We combine two orthogonal Cas9 proteins from Streptococcus pyogenes and Staphylococcus aureus to carry out a dual screen in which one gene is activated while a second gene is deleted in the same cell. We analyze the quantitative effects of activation and knockout to calculate genetic interaction and directionality scores for each gene pair. Based on the results from over 100,000 perturbed gene pairs, we reconstruct a directional dependency network for human K562 leukemia cells and demonstrate how our approach allows the determination of directionality in activating genetic interactions. Our interaction network connects previously uncharacterized genes to well-studied pathways and identifies targets relevant for therapeutic intervention
Classifier Robustness Enhancement Via Test-Time Transformation
It has been recently discovered that adversarially trained classifiers
exhibit an intriguing property, referred to as perceptually aligned gradients
(PAG). PAG implies that the gradients of such classifiers possess a meaningful
structure, aligned with human perception. Adversarial training is currently the
best-known way to achieve classification robustness under adversarial attacks.
The PAG property, however, has yet to be leveraged for further improving
classifier robustness. In this work, we introduce Classifier Robustness
Enhancement Via Test-Time Transformation (TETRA) -- a novel defense method that
utilizes PAG, enhancing the performance of trained robust classifiers. Our
method operates in two phases. First, it modifies the input image via a
designated targeted adversarial attack into each of the dataset's classes.
Then, it classifies the input image based on the distance to each of the
modified instances, with the assumption that the shortest distance relates to
the true class. We show that the proposed method achieves state-of-the-art
results and validate our claim through extensive experiments on a variety of
defense methods, classifier architectures, and datasets. We also empirically
demonstrate that TETRA can boost the accuracy of any differentiable adversarial
training classifier across a variety of attacks, including ones unseen at
training. Specifically, applying TETRA leads to substantial improvement of up
to , , and on CIFAR10, CIFAR100, and ImageNet,
respectively
D-brane interactions in type IIB plane-wave background
The cylinder diagrams that determine the static interactions between pairs of
Dp-branes in the type IIB plane wave background are evaluated. The resulting
expressions are elegant generalizations of the flat-space formulae that depend
on the value of the Ramond-Ramond flux of the background in a non-trivial
manner. The closed-string and open-string descriptions consistently transform
into each other under a modular transformation only when each of the
interacting D-branes separately preserves half the supersymmetries. These
results are derived for configurations of euclidean signature
D(p+1)-instantons but also generalize to lorentzian signature Dp-branes.Comment: 24 pages, Normalisation of boundary states correcte
Use of CCSDS Packets Over SpaceWire to Control Hardware
For the Lunar Reconnaissance Orbiter, the Command and Data Handling subsystem consisted of several electronic hardware assemblies that were connected with SpaceWire serial links. Electronic hardware would be commanded/controlled and telemetry data was obtained using the SpaceWire links. Prior art focused on parallel data buses and other types of serial buses, which were not compatible with the SpaceWire and the core flight executive (CFE) software bus. This innovation applies to anything that utilizes both SpaceWire networks and the CFE software. The CCSDS (Consultative Committee for Space Data Systems) packet contains predetermined values in its payload fields that electronic hardware attached at the terminus of the SpaceWire node would decode, interpret, and execute. The hardware s interpretation of the packet data would enable the hardware to change its state/configuration (command) or generate status (telemetry). The primary purpose is to provide an interface that is compatible with the hardware and the CFE software bus. By specifying the format of the CCSDS packet, it is possible to specify how the resulting hardware is to be built (in terms of digital logic) that results in a hardware design that can be controlled by the CFE software bus in the final applicatio
Ectopic expression of cyclase associated protein CAP restores the streaming and aggregation defects of adenylyl cyclase a deficient Dictyostelium discoideum cells
<p>Abstract</p> <p>Background</p> <p>Cell adhesion, an integral part of <it>D. discoideum </it>development, is important for morphogenesis and regulated gene expression in the multicellular context and is required to trigger cell-differentiation. G-protein linked adenylyl cyclase pathways are crucially involved and a mutant lacking the aggregation specific adenylyl cyclase ACA does not undergo multicellular development.</p> <p>Results</p> <p>Here, we have investigated the role of cyclase-associated protein (CAP), an important regulator of cell polarity and F-actin/G-actin ratio in the <it>aca<sup>- </sup></it>mutant. We show that ectopic expression of GFP-CAP improves cell polarization, streaming and aggregation in <it>aca<sup>- </sup></it>cells, but it fails to completely restore development. Our studies indicate a requirement of CAP in the ACA dependent signal transduction for progression of the development of unicellular amoebae into multicellular structures. The reduced expression of the cell adhesion molecule DdCAD1 together with csA is responsible for the defects in <it>aca<sup>- </sup></it>cells to initiate multicellular development. Early development was restored by the expression of GFP-CAP that enhanced the DdCAD1 transcript levels and to a lesser extent the csA mRNA levels.</p> <p>Conclusions</p> <p>Collectively, our data shows a novel role of CAP in regulating cell adhesion mechanisms during development that might be envisioned to unravel the functions of mammalian CAP during animal embryogenesis.</p
Type IIB Colliding Plane Waves
Four-dimensional colliding plane wave (CPW) solutions have played an
important role in understanding the classical non-linearities of Einstein's
equations. In this note, we investigate CPW solutions in --dimensional
Einstein gravity with a -form flux. By using an isomorphism with the
four-dimensional problem, we construct exact solutions analogous to the
Szekeres vacuum solution in four dimensions. The higher-dimensional versions of
the Khan-Penrose and Bell-Szekeres CPW solutions are studied perturbatively in
the vicinity of the light-cone. We find that under small perturbations, a
curvature singularity is generically produced, leading to both space-like and
time-like singularities. For , our results pertain to the collision of two
ten-dimensional type IIB Blau - Figueroa o'Farrill - Hull - Papadopoulos plane
waves.Comment: 20+10 pages, 2 figures, uses JHEP3.cls; v2: refs [3,10,22] corrected,
remark added below (3.9) on inexistence of conformally flat CPW in our
ansatz, final version to appear in JHE
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EMERGE: ESnet/MREN regional grid experimental NGI testbed
The shortened project focused on development of software package manager that could be applied on heterogeneous platforms. We successfully developed the package manager called the ''Grid Packaging Tool''. Further we used GPT to package the Globus Toolkit and GPT is being used today to package and distribute Globus
Large-N Universality of the Two-Dimensional Yang-Mills String
We exhibit the gauge-group independence (``universality'') of all normalized
non-intersecting Wilson loop expectation values in the large N limit of
two-dimensional Yang-Mills theory. This universality is most easily understood
via the string theory reformulation of these gauge theories. By constructing an
isomorphism between the string maps contributing to normalized Wilson loop
expectation values in the different theories, we prove the large N universality
of these observables on any surface. The string calculation of the Wilson loop
expectation value on the sphere also leads to an indication of the large N
phase transition separating strong- and weak-coupling phases.Comment: 18 pages, phyzzx macro, no figure
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