Abstract-This paper presents a quantitative comparison of different algorithms for the removal of stafflines from music images. It contains a survey of previously proposed algorithms and suggests a new skeletonization based approach. We define three different error metrics, compare the algorithms with respect to these metrics and measure their robustness with respect to certain image defects. Our test images are computer-generated scores on which we apply various image deformations typically found in real-world data. In addition to modern western music notation our test set also includes historic music notation such as mensural notation and lute tablature. Our general approach and evaluation methodology is not specific to staff removal, but applicable to other segmentation problems as well.

The elusive β − p + decay was observed in 11 Be by directly measuring the emitted protons and their energy distribution for the first time with the prototype Active Target Time Projection Chamber (pAT-TPC) in an experiment performed at ISAC-TRIUMF. The measured β − p + branching ratio is orders of magnitude larger than any previous theoretical model predicted. This can be explained by the presence of a narrow resonance in 11 B above the proton separation energy.

The Hough transform is a voting scheme for locating geometric objects in point clouds. This paper describes its application for detecting lines in three dimensional point clouds. For parameter quantization, a recently proposed method for Hough parameter space regularization is used. The voting process is done in an iterative way by selecting the line with the most votes and removing the corresponding points in each step. To overcome the inherent inaccuracies of the parameter space discretization, each line is estimated with an orthogonal least squares fit among the candidate points returned from the Hough transform. Source CodeThe reviewed C++ source code for this algorithm is available from the web page of this article 1 . Compilation and usage instruction are included in the README.txt file of the archive. Supplementary MaterialSix reference data sets are provided with the article. The data sets contain both synthetic data and experimental data of radioactive beams recorded in an active target time projection chamber (AT-TPC).

In the Letter, we presented the first direct observation of the elusive β −-delayed proton emission (β − p þ) in 11 Be using a time projection chamber. There is an error in the extracted logðftÞ, which should read 2.8(4). The corrected logðftÞ value does not affect the conclusions presented in the Letter, since it was only used to assert the allowed character of the transition, a conclusion that is not changed. We would like to point out that, assuming a pure Gamow-Teller (GT) transition, it yields BðGTÞ ¼ 5.5 þ8.3 −3.3 , thus, including the BðGTÞ < 3 limit for a single neutron decay within one sigma. It should be noted that, due to the small energy window, the uncertainty in the resonance energy amounts to nearly 75% of the error budget for the logðftÞ value. Thus, a more precise measurement of the resonance energy could bring the B(GT) to within theoretical limits without significantly affecting the measured branching ratio.

This article investigates the restoration of ultrasonic pulse-echo C-scan images by means of deconvolution with a point spread function (PSF). The deconvolution concept from linear system theory (LST) is linked to the wave equation formulation of the imaging process, and an analytic formula for the PSF of planar transducers is derived. For this analytic expression, different numerical and analytic approximation schemes for evaluating the PSF are presented. By comparing simulated images with measured C-scan images, we demonstrate that the assumptions of LST in combination with our formula for the PSF are a good model for the pulse-echo imaging process. To reconstruct the object from a C-scan image, we compare different deconvolution schemes: the Wiener filter, the ForWaRD algorithm, and the Richardson-Lucy algorithm. The best results are obtained with the Richardson-Lucy algorithm with total variation regularization. For distances greater or equal twice the near field distance, our experiments show that the numerically computed PSF can be replaced with a simple closed analytic term based on a far field approximation.