Sketch-based 3D Shape Retrieval using Convolutional Neural Networks

Retrieving 3D models from 2D human sketches has received considerable attention in the areas of graphics, image retrieval, and computer vision. Almost always in state of the art approaches a large amount of "best views" are computed for 3D models, with the hope that the query sketch matches one of these 2D projections of 3D models using predefined features. We argue that this two stage approach (view selection -- matching) is pragmatic but also problematic because the "best views" are subjective and ambiguous, which makes the matching inputs obscure. This imprecise nature of matching further makes it challenging to choose features manually. Instead of relying on the elusive concept of "best views" and the hand-crafted features, we propose to define our views using a minimalism approach and learn features for both sketches and views. Specifically, we drastically reduce the number of views to only two predefined directions for the whole dataset. Then, we learn two Siamese Convolutional Neural Networks (CNNs), one for the views and one for the sketches. The loss function is defined on the within-domain as well as the cross-domain similarities. Our experiments on three benchmark datasets demonstrate that our method is significantly better than state of the art approaches, and outperforms them in all conventional metrics.Comment: CVPR 201

Protein crystallogenesis of the arrowhead protease inhibitor-A

Les études sur la structure atomique des macromolécules biologiques ont été d'une grande importance en révélant des relations structurales et fonctionnelles d'enzymes, d'acides nucléiques et d'autres macromolécules dans divers systèmes biologiques. Dans la présente étude, la cristallogenèse et la cristallographie aux rayons X ont été utilisés pour déterminer la structure d'inhibiteur de protéinase A à une résolution atomique. Les inhibiteurs de protéinase A et B (API-A, -B) de la arrowhead, sont les deux principaux composés inhibiteurs qui sont purifiés à partir de la arrowhead (Sagittaria sagittifolia, Linn.). Ils sont des inhibiteurs à double tête multifonctionnels de diverses protéases. La structure du complexe ternaire de l'inhibiteur API lié à deux trypsines a été déterminée. Cependant, la structure tridimensionnelle de l'apoenzyme API-A est encore inconnue. A cet effet, la cristallogenèse de l’apoenzyme API-A a été réalisée. Après des étapes de purification et de cristallisation appropriées, des cristaux de l’apoenzyme API-A d’une qualité permettant la diffraction des rayons-X à haute résolution ont été obtenus en utilisant la méthode de diffusion de vapeur dans une goutte suspendue. Un ensemble complet de données de diffraction des rayons-X jusqu’à une résolution de 3,10 Å a été obtenu avec un crystal en forme de diamant, dont, le groupe d'espace a été déterminé comme étant P1. Ces données seront importantes pour comprendre la fonction d'API-A dans des systèmes biologiques.Structural studies of biological macromolecules at atomic resolution have revealed many specific aspects of the structure/function relationships of the enzymes, nucleic acids and other macromolecules in biological systems. In the present study, protein crystallogenesis and X-ray crystallography were used to determine the structure of the protease inhibitor A at atomic resolution. The arrowhead protease inhibitors A and B (API-A, -B), are the two major inhibitor components which are purified from the tubes of arrowhead (Sagittaria sagittifolia, Linn.). Both API-A and API-B are double-headed multifunctional protease inhibitors. The ternary structure of the inhibitor API-A complex with two trypsins has been reported. However, the three-dimensional structure of the apoenzyme API-A is still unknown. In this regard, crystallogenesis of apoenzyme API-A was studied. After proper purification and crystallization steps, diffraction-quality crystals of the apoenzyme API-A were obtained, using the hanging drop vapor diffusion method. Moreover, a complete set of X-ray diffraction data was collected up to a resolution of 3.10 Å, using a diamond-shaped crystal whose space group was determined to be P1. These data will be important for understanding the function of API-A in biological systems