Categorizing and correlating diffractivity attributes with seismic-reflection attributes using autoencoder networks

Seismic attributes play a crucial role in fault interpretation and mapping fracture density. Conventionally, seismic attributes derived from migrated reflections are used for this purpose. The attributes derived from the other counterparts of the recorded wavefield are often ignored and excluded from the categorization. We have performed categorization of the attributes derived from the diffracted part of the wavefield and combine them into a new seismic attribute class, which we call diffractivity attributes. The extraction of diffractivity attributes is based on the 3D Kirchhoff time migration operator that includes a dynamic muting. We distinguish three major classes in the diffractivity attributes, which describe geometric and amplitude properties of the seismic diffractions. We assign point and edge diffraction focusing as well as the azimuth to the geometric class. The amplitudes of the isolated seismic diffractions are used to extract the instantaneous attributes based on the complex-trace approach. The instantaneous amplitudes, phase, frequency, and sweetness build up the instantaneous attribute class. We perform a spectral decomposition of the isolated diffractions into the isofrequencies using the wavelet approach. The isofrequencies compose the spectral-decomposition class. We also link the new diffractivity class to the conventional seismic reflection attributes. We use a deep learning approach based on convolutional neural networks for classifying and correlating the diffractivity attributes.

Effects of variable canopy retention harvest on epixylic bryophytes in boreal black spruce – feathermoss forests1This article is one of a selection of papers from the International Symposium on Dynamics and Ecological Services of Deadwood in Forest Ecosystems.

Modification of forest attributes and structural components like downed wood (DW) during forest harvest can lead to local species loss. Epixylic bryophytes have been proposed as good indicators of such changes. Unharvested control, variable canopy retention, and single pass harvest represent a gradient in forest harvest impact and can be used to test the response of epixylic bryophytes to different levels of environmental change. The objective of this study was to see if variable canopy retention attenuates environmental change associated with harvesting, consequently maintaining an epixylic community more similar to unharvested stands than single pass harvesting. Environmental conditions and DW characteristics were sampled on 225 DW pieces distributed in 45 permanent plots. Results showed that treatment affected epixylic richness through its impact on canopy openness and DW diameter and decomposition class. Fewer species were found in more open habitats and more species were found on bigger and more decomposed DW. Most epixylic species were more commonly found on the forest floor than on the DW. In conclusion, variable canopy retention harvest offered microclimatic conditions and DW availability and quality more suitable for epixylic species than single pass harvest, which was less suitable for epixylic species.

Decomposition Varieties in Semisimple Lie Algebras

The notion of decompositon class in a semisimple Lie algebra is a common generalization of nilpotent orbits and the set of regular semisimple elements.We prove that the closure of a decomposition class has many properties in common with nilpotent varieties, e.g., its normalization has rational singularities.The famous Grothendieck simultaneous resolution is related to the decomposition class of regular semisimple elements. We study the properties of the analogous commutative diagrams associated to an arbitrary decomposition class.

Polyamine and Histamine Content of Rockfish, Salmon, Lobster, and Shrimp as an Indicator of Decomposition

A chemical method to determine decomposition in rockfish, salmon, lobster, and shrimp was developed. Dansyl derivatives were formed from extracts of these products and separated using gradient elution high pressure liquid chromatography. The dansylated polyamines, putrescine, cadaverine, spermidine, and spermine, and the amine histamine were quantitated, and the results were entered into an index formula. The resulting index was used to classify each product into passable (class 1), initial decomposition (class 2), and advanced decomposition (class 3). A comparison of results obtained by the chemical classification of 21 samples (rockfish, salmon, and lobster) showed good correlation with organoleptic evaluations of the same products by 23 examiners. The chemical index classified the samples correctly 90.5% of the time vs. an 83.9% correct classification by organoleptic means. Analysis of shrimp composites of the 3 organoleptic classes showed a similar relationship between the chemical index and the degree of decomposition.