Charles Bloom

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The affine transform is a fundamental computer graphics tool. While there are many situations which require the linear combination of such transformations, most practioners find these operations troublesome due to the non-linear nature of rotations. Alexa [2002] proposed a methodology for treating transforms as linear, and although this is a worthwhile(More)
Introduction A new compression algorithm is presented which may either be considered an improvement to dictionary coding or an improvement to context coding. This algorithm works by reducing the set of available window position, for an LZ77 encoder to match from; thus fewer bits are required to indicate the match-from location, and higher compression is(More)
LEAP is a coached practice environment that optimizes the learning process by maintaining and consulting a detailed student model. LEAP calculates a student model score for every action, exercise, and topic the student tries, then uses the scores both to provide feedback to the student and to select topics, exercises and actions for the student to practice.(More)
The PPM algorithm is known to be one of the most powerful data compression techniques. However, it uses a large amount of memory, and operates slowly. Several new techniques were explored which address the problems with PPM, at each order of context modeling : the DefSum order-0 coder. the ListLRU order-l coder, the StaticHuff order-l coder, and the PPMCB(More)
The positive and negative cooperativity and apparent half-site reactivity of the Co(II)-substituted insulin hexamer are well-described by a three-state allosteric model involving ligand-mediated interconversions between the three states: T3T3' right harpoon over left harpoon T3o R3o right harpoon over left harpoon R3R3' [Bloom, C. R., Heymann, R.,(More)
The nature of cooperative allosteric interactions has been the source of controversy since the ground-breaking studies of oxygen binding to hemoglobin. Until recently, quantitative examples of a model based on the inherent symmetry and asymmetry of oligomeric proteins have been lacking. This laboratory has used the phenolic ligand binding characteristics of(More)
The insulin hexamer is an allosteric protein which displays positive and negative cooperativity and half-site reactivity that is modulated by strong homotropic and heterotropic ligand binding interactions at two different loci. These loci consist of phenolic pockets situated on the dimer-dimer interfaces of T-R and R-R subunit pairs and of anion sites(More)
By using ultra-violet and visible absorbance in conjunction with high field 1H-nuclear magnetic resonance spectroscopy, the insulin hexamer has been shown to undergo two allosteric transitions in solution involving three allosteric states (T6<-->T3 R3<-->R6). A simple mathematical model consisting of four variables has been derived that quantitatively(More)
The binding of phenolic ligands to the insulin hexamer occurs as a cooperative allosteric process. Investigations of the allosteric mechanism from this laboratory resulted in the postulation of a model consisting of a three-state conformational equilibrium and the derivation of a mathematical expression to describe the insulin system. The proposed mechanism(More)