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Collaborating Authors

 Shekarforoush, Shayan


Improving Ab-Initio Cryo-EM Reconstruction with Semi-Amortized Pose Inference

arXiv.org Artificial Intelligence

Cryo-Electron Microscopy (cryo-EM) is an increasingly popular experimental technique for estimating the 3D structure of macromolecular complexes such as proteins based on 2D images. These images are notoriously noisy, and the pose of the structure in each image is unknown \textit{a priori}. Ab-initio 3D reconstruction from 2D images entails estimating the pose in addition to the structure. In this work, we propose a new approach to this problem. We first adopt a multi-head architecture as a pose encoder to infer multiple plausible poses per-image in an amortized fashion. This approach mitigates the high uncertainty in pose estimation by encouraging exploration of pose space early in reconstruction. Once uncertainty is reduced, we refine poses in an auto-decoding fashion. In particular, we initialize with the most likely pose and iteratively update it for individual images using stochastic gradient descent (SGD). Through evaluation on synthetic datasets, we demonstrate that our method is able to handle multi-modal pose distributions during the amortized inference stage, while the later, more flexible stage of direct pose optimization yields faster and more accurate convergence of poses compared to baselines. Finally, on experimental data, we show that our approach is faster than state-of-the-art cryoAI and achieves higher-resolution reconstruction.


Self-Attention Equipped Graph Convolutions for Disease Prediction

arXiv.org Machine Learning

SELF-A TTENTION EQUIPPED GRAPH CONVOLUTIONS FOR DISEASE PREDICTION Anees Kazi 1, S.Arvind krishna 2, Shayan Shekarforoush 3, Karsten Kortuem 4, Shadi Albarqouni 1, Nassir Navab 1, 5 1 Computer Aided Medical Procedures, Technische Universität München, Germany 2 National Institute of Technology Tiruchirappalli, India 3 Sharif University of Technology, Iran 4 Augenklinik der Universität, Klinikum der Universität München, Germany 5 Johns Hopkins University, Baltimore MD, USA ABSTRACT Multi-modal data comprising imaging (MRI, fMRI, PET, etc.) and non-imaging (clinical test, demographics, etc.) data can be collected together and used for disease prediction. Such diverse data gives complementary information about the patient's condition to make an informed diagnosis. A model capable of leveraging the individuality of each multi-modal data is required for better disease prediction. We propose a graph convolution based deep model which takes into account the distinctiveness of each element of the multi-modal data. We incorporate a novel self-attention layer, which weights every element of the demographic data by exploring its relation to the underlying disease.