The arrangement of compact chromatin of G0 lymphocytes was studied in three-dimensional reconstru... more The arrangement of compact chromatin of G0 lymphocytes was studied in three-dimensional reconstructions of the ensemble of the chromatin and of individual compact chromatin bodies. Rat spleen was serially cut and sections were contrasted with procedures preferential for DNA. Electron microscopy images were digitized, processed, and displayed using a commercial soft-ware package, complemented by a system for three-dimensional reconstruction and analysis developed by us on an IBM-compatible microcomputer provided with an image acquisition board. The reconstructions showed a continuous layer of compact chromatin in contact with the nuclear envelope that prevents the automatic recognition of individual chromatin clumps. The ensemble of the arrangement of compact chromatin was found to be very similar in different lymphocytes. After morphological filtering procedures, the initial mass was divided into individual bodies of compact chromatin, which were tagged. Most of these bodies contact the nuclear envelope. The number of bodies as well as the number of contacts with the envelope are similar and correspond to a haploid number of chromosomes. The largest body is always the one containing nucleolus-associated chromatin. When the cell has two nucleoli, the nucleolus-associated chromatin bodies contact the envelope in diametrically opposed areas. This feature was also described in rat liver cells. It is concluded that: (a) the individualized compact chromatin bodies do not correspond to an entire chromosome or to a pair of chromosomes; (b) the arrangement of compact chromatin is not identical in each G0 lymphocyte, but there are patterns that are repeated with limited changes; and (c) there are common features that appear in different cell types of individuals of the same species.
A complete system for creating the performance of a virtual character is described. Stereo web-ca... more A complete system for creating the performance of a virtual character is described. Stereo web-cameras perform marker based motion capture to obtain rigid head motion and non-rigid facial expression motion. Acquired 3D points are then mapped onto a 3D face model with a virtual muscle animation to create face expressions. Muscle inverse kinematics updates muscle contraction parameters based on marker motion to create the character’s performance. Advantages of the system are reduced character creation time by using virtual muscles and a dynamic skin model, a novel way of applying markers to a face animation system, and its low cost hardware requirements, capable of running on standard hardware and making it suitable for interactive media in end-user environments.
The arrangement of compact chromatin of G0 lymphocytes was studied in three-dimensional reconstru... more The arrangement of compact chromatin of G0 lymphocytes was studied in three-dimensional reconstructions of the ensemble of the chromatin and of individual compact chromatin bodies. Rat spleen was serially cut and sections were contrasted with procedures preferential for DNA. Electron microscopy images were digitized, processed, and displayed using a commercial soft-ware package, complemented by a system for three-dimensional reconstruction and analysis developed by us on an IBM-compatible microcomputer provided with an image acquisition board. The reconstructions showed a continuous layer of compact chromatin in contact with the nuclear envelope that prevents the automatic recognition of individual chromatin clumps. The ensemble of the arrangement of compact chromatin was found to be very similar in different lymphocytes. After morphological filtering procedures, the initial mass was divided into individual bodies of compact chromatin, which were tagged. Most of these bodies contact the nuclear envelope. The number of bodies as well as the number of contacts with the envelope are similar and correspond to a haploid number of chromosomes. The largest body is always the one containing nucleolus-associated chromatin. When the cell has two nucleoli, the nucleolus-associated chromatin bodies contact the envelope in diametrically opposed areas. This feature was also described in rat liver cells. It is concluded that: (a) the individualized compact chromatin bodies do not correspond to an entire chromosome or to a pair of chromosomes; (b) the arrangement of compact chromatin is not identical in each G0 lymphocyte, but there are patterns that are repeated with limited changes; and (c) there are common features that appear in different cell types of individuals of the same species.
A complete system for creating the performance of a virtual character is described. Stereo web-ca... more A complete system for creating the performance of a virtual character is described. Stereo web-cameras perform marker based motion capture to obtain rigid head motion and non-rigid facial expression motion. Acquired 3D points are then mapped onto a 3D face model with a virtual muscle animation to create face expressions. Muscle inverse kinematics updates muscle contraction parameters based on marker motion to create the character’s performance. Advantages of the system are reduced character creation time by using virtual muscles and a dynamic skin model, a novel way of applying markers to a face animation system, and its low cost hardware requirements, capable of running on standard hardware and making it suitable for interactive media in end-user environments.
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Papers by Jorge Marquez