130 research outputs found
One-loop four-point function in noncommutative {\cal N}=4 Yang-Mills theory
We compute the one-loop four-point function in {\cal N}=4 supersymmetric
Yang-Mills theory with gauge group U(N). We perform the calculation in {\cal
N}=1 superspace using the background field method and obtain the complete
off-shell contributions to the effective action from planar and non planar
supergraphs. In the low-energy approximation the result simplifies and we can
study its properties under gauge transformations. It appears that the nonplanar
contributions do not maintain the gauge invariance of the classical action.Comment: LaTex, 14 pages, 2 figure
PRETZEL: Opening the Black Box of Machine Learning Prediction Serving Systems
Machine Learning models are often composed of pipelines of transformations.
While this design allows to efficiently execute single model components at
training time, prediction serving has different requirements such as low
latency, high throughput and graceful performance degradation under heavy load.
Current prediction serving systems consider models as black boxes, whereby
prediction-time-specific optimizations are ignored in favor of ease of
deployment. In this paper, we present PRETZEL, a prediction serving system
introducing a novel white box architecture enabling both end-to-end and
multi-model optimizations. Using production-like model pipelines, our
experiments show that PRETZEL is able to introduce performance improvements
over different dimensions; compared to state-of-the-art approaches PRETZEL is
on average able to reduce 99th percentile latency by 5.5x while reducing memory
footprint by 25x, and increasing throughput by 4.7x.Comment: 16 pages, 14 figures, 13th USENIX Symposium on Operating Systems
Design and Implementation (OSDI), 201
Two-point functions for N=4 Konishi-like operators
We compute the two-point function of Konishi-like operators up to one-loop
order, in N=4 supersymmetric Yang-Mills theory. We work perturbatively in N=1
superspace. We find the expression expected on the basis of superconformal
invariance and determine the normalization of the correlator and the anomalous
dimension of the operators to order g^2 in the coupling constant.Comment: 10 pages, 3 figures; added references and some clarifying comment
Exact anomalous dimensions of {\cal N}=4 Yang-Mills operators with large R charge
In a {\cal N}=1 superspace formulation of {\cal N}=4 Yang-Mills theory we
obtain the anomalous dimensions of chiral operators with large R charge J \to
\infty keeping g^2 N/J^2 finite, to all orders of perturbation theory in the
planar limit. Our result proves the conjecture that the anomalous dimensions
are indeed finite in the above limit. This amounts to an exact check of the
proposed duality between a sector of {\cal N}=4 Yang-Mills theory with large R
charge J and string theory in a pp-wave background.Comment: 6 pages, LaTex; v2: minor change
Three-dimensional easy morphological (3-DEMO) classification of scoliosis, part I
BACKGROUND: While scoliosis has, for a long time, been defined as a three-dimensional (3D) deformity, morphological classifications are confined to the two dimensions of radiographic assessments. The actually existing 3-D classification proposals have been developed in research laboratories and appear difficult to be understood by clinicians. AIM OF THE STUDY: The aim of this study was to use the results of a 3D evaluation to obtain a simple and clinically oriented morphological classification (3-DEMO) that might make it possible to distinguish among different populations of scoliotic patients. METHOD: We used a large database of evaluations obtained through an optoelectronic system (AUSCAN) that gives a 3D reconstruction of the spine. The horizontal view was used, with a spinal reference system (Top View). An expert clinician evaluated the morphological reconstruction of 149 pathological spines in order to find parameters that could be used for classificatory ends. These were verified in a mathematical way and through computer simulations: some parameters had to be excluded. Pathological data were compared with those of 20 normal volunteers. RESULTS: We found three classificatory parameters, which are fully described and discussed in this paper: Direction, the angle between spinal pathological and normal AP axis; Shift, the co-ordinates of the barycentre of the Top View ; Phase, the parameter describing the spatial evolution of the curve. Using these parameters it was possible to distinguish normal and pathological spines, to classify our population and to differentiate scoliotic patients with identical AP classification but different 3D behaviors. CONCLUSION: The 3-DEMO classification offers a new and simple way of viewing the spine through an auxiliary plane using a spinal reference system. Further studies are currently under way to compare this new system with the existing 3-D classifications, to obtain it using everyday clinical and x-rays data, and to develop a triage for clinical use
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