Weakly- and Semi-Supervised Panoptic Segmentation

We present a weakly supervised model that jointly performs both semantic- and instance-segmentation -- a particularly relevant problem given the substantial cost of obtaining pixel-perfect annotation for these tasks. In contrast to many popular instance segmentation approaches based on object detectors, our method does not predict any overlapping instances. Moreover, we are able to segment both "thing" and "stuff" classes, and thus explain all the pixels in the image. "Thing" classes are weakly-supervised with bounding boxes, and "stuff" with image-level tags. We obtain state-of-the-art results on Pascal VOC, for both full and weak supervision (which achieves about 95% of fully-supervised performance). Furthermore, we present the first weakly-supervised results on Cityscapes for both semantic- and instance-segmentation. Finally, we use our weakly supervised framework to analyse the relationship between annotation quality and predictive performance, which is of interest to dataset creators.Comment: ECCV 2018. The first two authors contributed equall

Conditional probabilities for a single photon at a beam splitter

Published versio

Optical vernier technique for in-situ measurement of the length of long Fabry-Perot cavities

We propose a method for in-situ measurement of the length of kilometer size Fabry-Perot cavities in laser gravitational wave detectors. The method is based on the vernier, which occurs naturally when the laser incident on the cavity has a sideband. By changing the length of the cavity over several wavelengths we obtain a set of carrier resonances alternating with sideband resonances. From the measurement of the separation between the carrier and a sideband resonance we determine the length of the cavity. We apply the technique to the measurement of the length of a Fabry-Perot cavity in the Caltech 40m Interferometer and discuss the accuracy of the technique.Comment: LaTeX 2e, 12 pages, 4 figure

Raman scattering investigation of electron-phonon coupling in carbon substituted MgB<SUB>2</SUB>

Room temperature Raman scattering measurements have been carried out on well characterized samples of MgB2-xCx. The Raman line corresponding to the E2g phonon mode shows progressive hardening from 620 cm&#8722;1 in pristine MgB2 to 775 cm&#8722;1 in the sample with carbon fraction x = 0.2. The corresponding line width on the other hand increases from a value of about 220 to 286 cm&#8722;1 in samples with x = 0.1, beyond which it decreases to a value of 167 cm&#8722;1 for x = 0.2. From the average mode frequency and the line width obtained from Raman measurements and taking the values of N(0) obtained from the calculated variation in &#963;-hole density of states in MgB2-xCx, the electron-phonon coupling strength to the E2g phonon, &#955;2g, is evaluated using Allen's formula. This remains large for low C fraction, but shows a rapid decrease for x&gt;0.10. Using this value of &#955;2gappropriately weighted, TC is obtained from McMillan's equation. These values are in good agreement with the experimentally measured TC variation in MgB2-xCx