GLAVITU:A Hybrid CNN-Transformer for Multi-Regional Glacier Mapping from Multi-Source Data

Glacier mapping is essential for studying and monitoring the impacts of climate change. However, several challenges such as debris-covered ice and highly variable landscapes across glacierized regions worldwide complicate large-scale glacier mapping in a fully-automated manner. This work presents a novel hybrid CNN-transformer model (GlaViTU) for multi-regional glacier mapping. Our model outperforms three baseline models - SETR-B/16, ResU-Net and TransU-Net - achieving a higher mean IoU of 0.875 and demonstrates better generalization ability. The proposed model is also parameter-efficient, with approximately 10 and 3 times fewer parameters than SETR-B/16 and ResU-Net, respectively. Our results provide a solid foundation for future studies on the application of deep learning methods for global glacier mapping. To facilitate reproducibility, we have shared our data set, codebase and pretrained models on GitHub at https://github.com/konstantin-a-maslov/GlaViTU-IGARSS2023.</p

Synchrotron radiation solution x-ray scattering study of the pH-dependence of the quarternary structure of yeast pyruvate decarboxylase

The pH dependence of the quaternary structure of pyruvate decarboxylase from yeast wasstudied in therange 6.2 < pH < 8.4. There is an equilibrium with a midpoint around pH 7.5 betweentetramers and dimers, and the catalytic activity of the enzyme depends on the volume fraction of tetramer.This equilibrium may provide an additional regulating mechanism besides substrate activation sinceaccumulation of pyruvate would lead to a reduction in pH and hence an increase of the concentration ofthe catalytically active tetramer. Radiation damage during the X-ray scattering experiments results in ashift of this equilibrium and in the formation of octamers. These effects could be circumvented and analyzedusing experimental and data processing methods which can be readily applied to other radiation-sensitivesystems. The low-resolution shapes of the dimers and tetramers were determined from the scattering curvesusing spherical harmonics. The results indicate that a conformational change must occur in the dimersupon formation of the tetramers, in agreement with earlier circular dichroism measurements.