Identification of peaks in multidimensional coincidence γ-ray spectra

Morháč, M.; Kliman, J.; Matoušek, V.; Veselský, M.; Turzo, I.

doi:10.1016/s0168-9002(99)01005-0

Cited by 89 publications

(48 citation statements)

References 11 publications

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“…As the figure shows, these galaxies were clearly classified incorrectly by Ganalyzer. While the radial intensity plots show that some of the peaks shift as the distance from the galaxy center changes, in some cases the peaks are not always detected correctly, and improving the peak detection used in this study (Morhac et al 2000) might improve the performance of the galaxy classification. Another limitation of Ganalyzer is that the analysis is dependent on the arms, and therefore if the resolution of the image is too low and the arms cannot be seen the galaxy might not be analyzed correctly.…”

Section: Resultsmentioning

confidence: 84%

“…To use the shift of the peaks in the radial intensity plot for detecting spirality, the peaks are first detected using an automatic peak detection algorithm (Morhac et al 2000), with the parameters σ = 10, threshold = 0.05, and iterations = 1, as described in Morhac et al (2000). Figure 3 shows the peaks detected in the galaxy images of Figure 2, such that the radial distance is between 0.4r and 0.75r, where r is the radius of the galaxy described in Section 2.1.…”

Section: Detecting Spiralitymentioning

confidence: 99%

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Ganalyzer: A Tool for Automatic Galaxy Image Analysis

Shamir

2011

ApJ

149

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We describe Ganalyzer, a model-based tool that can automatically analyze and classify galaxy images. Ganalyzer works by separating the galaxy pixels from the background pixels, finding the center and radius of the galaxy, generating the radial intensity plot, and then computing the slopes of the peaks detected in the radial intensity plot to measure the spirality of the galaxy and determine its morphological class. Unlike algorithms that are based on machine learning, Ganalyzer is based on measuring the spirality of the galaxy, a task that is difficult to perform manually, and in many cases can provide a more accurate analysis compared to manual observation. Ganalyzer is simple to use, and can be easily embedded into other image analysis applications. Another advantage is its speed, which allows it to analyze ∼10,000,000 galaxy images in five days using a standard modern desktop computer. These capabilities can make Ganalyzer a useful tool in analyzing large data sets of galaxy images collected by autonomous sky surveys such as SDSS, LSST, or DES. The software is available for free download at

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Section: Resultsmentioning

confidence: 84%

Section: Detecting Spiralitymentioning

confidence: 99%

Ganalyzer: A Tool for Automatic Galaxy Image Analysis

Shamir

2011

ApJ

149

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“…Each of the 35 lines is then searched for peaks using a peak detection algorithm (Morháč et al 2000), and each group of peaks is considered to be associated with one arm of the galaxy (Shamir 2011a). The slope of the peaks can be used to differentiate between elliptical and spiral galaxies (Shamir 2011a), and the sign of the slope can identify the direction of the galaxy rotation (Shamir 2012).…”

Section: Image Analysis Methodsmentioning

confidence: 99%

Characteristics of clockwise and counterclockwise spiral galaxies

Hoehn

Shamir

2014

Astron Nachr

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We compared measurements of 126 501 spiral galaxies to test whether the photometry of galaxies that rotate clockwise is different from the photometry of galaxies that rotate counterclockwise for the purpose of testing whether there is a link between photometry and spin direction of galaxies. The rotation directionality of the galaxies was determined by converting the galaxy image to its radial intensity plot, and then the galaxies in each 30 o RA sector were separated into clockwise and counterclockwise rotating galaxies. The mean and standard deviation of SDSS DR7 photometric attributes of clockwise and counterclockwise rotating galaxies were then compared. The results show no significant difference between galaxies that rotate clockwise and galaxies that rotate counterclockwise.

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“…Deconvolution is the process of separating an observed signal into two component parts. We used a deconvolution algorithm developed to simultaneously estimate both peak location and background signal level in the presence of noise, as implemented in the R package Peaks (Morhač et al 2000; Morhač 2008). Sudden rises in activity that are sustained tend to be classified as peaks, while gentler rises tend to be classified as background.…”

Section: Methodsmentioning

confidence: 99%

Bigger is better: honeybee colonies as distributed information-gathering systems

2013

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In collectively foraging groups, communication about food resources can play an important role in the organization of the group’s activity. For example, the honeybee dance communication system allows colonies to selectively allocate foragers among different floral resources according to their quality. Because larger groups can potentially collect more information than smaller groups, they might benefit more from communication because it allows them to integrate and use that information to coordinate forager activity. Larger groups might also benefit more from communication because it allows them to dominate high-value resources by recruiting large numbers of foragers. By manipulating both colony size and the ability to communicate location information in the dance, we show that larger colonies of honeybees benefit more from communication than do smaller colonies. In fact, colony size and dance communication worked together to improve foraging performance; the estimated net gain per foraging trip was highest in larger colonies with unimpaired communication. These colonies also had the earliest peaks in foraging activity, but not the highest ones. This suggests they may find and recruit to resources more quickly, but not more heavily. The benefits of communication we observed in larger colonies are thus likely a result of more effective informationgathering due to massive parallel search rather than increased competitive ability due to heavy recruitment.

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Identification of peaks in multidimensional coincidence γ-ray spectra

Cited by 89 publications

References 11 publications

Ganalyzer: A Tool for Automatic Galaxy Image Analysis

Ganalyzer: A Tool for Automatic Galaxy Image Analysis

Characteristics of clockwise and counterclockwise spiral galaxies

Bigger is better: honeybee colonies as distributed information-gathering systems

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