247 research outputs found
Wave function of the quantum black hole
We show that the Wald Noether charge entropy is canonically conjugate to the
opening angle at the horizon. Using this canonical relation we extend the
Wheeler-DeWitt equation to a Schroedinger equation in the opening angle,
following Carlip and Teitelboim. We solve the equation in the semiclassical
approximation by using the correspondence principle and find that the solutions
are minimal uncertainty wavefunctions with a continuous spectrum for the
entropy and therefore also of the area of the black hole horizon. The fact that
the opening angle fluctuates away from its classical value of 2 pi indicates
that the quantum black hole is a superposition of horizonless states. The
classical geometry with a horizon serves only to evaluate quantum expectation
values in the strict classical limit.Comment: 14 pages v2. misspelled name in abstract correcte
The Effect of System Workload on Error Latency: An Experimental Study
Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / N00014-84-C-0149Graduate Research Board, University of Illinois at Urbana-Champaig
CalibNet: Geometrically Supervised Extrinsic Calibration using 3D Spatial Transformer Networks
3D LiDARs and 2D cameras are increasingly being used alongside each other in
sensor rigs for perception tasks. Before these sensors can be used to gather
meaningful data, however, their extrinsics (and intrinsics) need to be
accurately calibrated, as the performance of the sensor rig is extremely
sensitive to these calibration parameters. A vast majority of existing
calibration techniques require significant amounts of data and/or calibration
targets and human effort, severely impacting their applicability in large-scale
production systems. We address this gap with CalibNet: a self-supervised deep
network capable of automatically estimating the 6-DoF rigid body transformation
between a 3D LiDAR and a 2D camera in real-time. CalibNet alleviates the need
for calibration targets, thereby resulting in significant savings in
calibration efforts. During training, the network only takes as input a LiDAR
point cloud, the corresponding monocular image, and the camera calibration
matrix K. At train time, we do not impose direct supervision (i.e., we do not
directly regress to the calibration parameters, for example). Instead, we train
the network to predict calibration parameters that maximize the geometric and
photometric consistency of the input images and point clouds. CalibNet learns
to iteratively solve the underlying geometric problem and accurately predicts
extrinsic calibration parameters for a wide range of mis-calibrations, without
requiring retraining or domain adaptation. The project page is hosted at
https://epiception.github.io/CalibNetComment: Appeared in the proccedings of the IEEE International Conference on
Intelligent Robots and Systems (IROS) 201
Gram Stains: A Resource for Retrospective Analysis of Bacterial Pathogens in Clinical Studies
We demonstrate the feasibility of using qPCR on DNA extracted from vaginal Gram stain slides to estimate the presence and relative abundance of specific bacterial pathogens. We first tested Gram stained slides spiked with a mix of 108 cfu/ml of Escherichia coli and 105cfu/ml of Lactobacillus acidophilus. Primers were designed for amplification of total and species-specific bacterial DNA based on 16S ribosomal gene regions. Sample DNA was pre-amplified with nearly full length 16S rDNA ribosomal gene fragment, followed by quantitative PCR with genera and species-specific 16S rDNA primers. Pre-amplification PCR increased the bacterial amounts; relative proportions of Escherichia coli and Lactobacillus recovered from spiked slides remained unchanged. We applied this method to forty two archived Gram stained slides available from a clinical trial of cerclage in pregnant women at high risk of preterm birth. We found a high correlation between Nugent scores based on bacterial morphology ofLactobacillus, Gardenerella and Mobiluncus and amounts of quantitative PCR estimated genus specific DNA (rrn copies) from Gram stained slides. Testing of a convenience sample of eight paired vaginal swabs and Gram stains freshly collected from healthy women found similar qPCR generated estimates of Lactobacillus proportions from Gram stained slides and vaginal swabs. Archived Gram stained slides collected from large scale epidemiologic and clinical studies represent a valuable, untapped resource for research on the composition of bacterial communities that colonize human mucosal surfaces
- …