Stress and deformation analysis of plane-strain rolling process

A finite-element elastic-plastic deformation analysis is required in order to predict a complete stress and deformation in a material for metal forming. There have been a few attempts for rolling analysis using the elastic-plastic code, because the boundary conditions between roll and deforming material become complicated. In this study, an elastic-plastic plane-strain rolling analysis with friction has been attempted by the updated Lagrange code. Both slipping and sticking were taken into account for boundary conditions between roll and material. The stress and deformation analysis is performed using a nonsymmetric stiffness matrix solution (for curved and frictional boundaries). The elastic-plastic analysis, coupled with the proposed frictional boundary model, evidently provides a reliable stress and deformation solution in the metal rolling process.     

Properties of plasma oxyfluorides grown on GaAs

A glow discharge technique is used to grow native oxides and oxyfluorides on GaAs. The capacitance-voltage and conductance-voltage measurements of the resulting metal/insulator/semiconductor structures show vastly different properties. Specifically, the density of interface states in the d.c.-to-5 MHz range appears to be much lower at the oxyfluoride interface than at the oxide interface. Secondary ion mass spectroscopy analyses indicate that some fluorine ions are mobile and the fluorine concentration is reduced by about an order of magnitude after a thermal anneal at 450°C. X-ray photoemission studies indicate that the glass is a mixture of GaF₃ and AsOF₃ molecules.     

Discovering diverse association rules from multidimensional schema

The integration of data mining techniques with data warehousing is gaining popularity due to the fact that both disciplines complement each other in extracting knowledge from large datasets. However, the majority of approaches focus on applying data mining as a front end technology to mine data warehouses. Surprisingly, little progress has been made in incorporating mining techniques in the design of data warehouses. While methods such as data clustering applied on multidimensional data have been shown to enhance the knowledge discovery process, a number of fundamental issues remain unresolved with respect to the design of multidimensional schema. These relate to automated support for the selection of informative dimension and fact variables in high dimensional and data intensive environments, an activity which may challenge the capabilities of human designers on account of the sheer scale of data volume and variables involved. In this research, we propose a methodology that selects a subset of informative dimension and fact variables from an initial set of candidates. Our experimental results conducted on three real world datasets taken from the UCI machine learning repository show that the knowledge discovered from the schema that we generated was more diverse and informative than the standard approach of mining the original data without the use of our multidimensional structure imposed on it.     

Myosin Assembly, Maintenance and Degradation in Muscle: Role of the Chaperone UNC-45 in Myosin Thick Filament Dynamics

Myofibrillogenesis in striated muscle cells requires a precise ordered pathway to assemble different proteins into a linear array of sarcomeres. The sarcomere relies on interdigitated thick and thin filaments to ensure muscle contraction, as well as properly folded and catalytically active myosin head. Achieving this organization requires a series of protein folding and assembly steps. The folding of the myosin head domain requires chaperone activity to attain its functional conformation. Folded or unfolded myosin can spontaneously assemble into short myosin filaments, but further assembly requires the short and incomplete myosin filaments to assemble into the developing thick filament. These longer filaments are then incorporated into the developing sarcomere of the muscle. Both myosin folding and assembly require factors to coordinate the formation of the thick filament in the sarcomere and these factors include chaperone molecules. Myosin folding and sarcomeric assembly requires association of classical chaperones as well as folding cofactors such as UNC-45. Recent research has suggested that UNC-45 is required beyond initial myosin head folding and may be directly or indirectly involved in different stages of myosin thick filament assembly, maintenance and degradation.     

Approximate Musical Evolution

Musical patterns that recur in approximate, rather thanidentical, form within a composition (or body of musical work)are considered to be of considerable importance in musicanalysis. Here we consider the ``evolutionary chain problem'':this is the problem of computing a chain of all ``motif''recurrences, each of which is a transformation of (``similar''to) the original motif, but each of which is progressivelyfurther from the original. Here we consider several variants ofthe evolutionary chain problem and we present efficientalgorithms for solving them.     

Tailoring Enzyme Stringency Masks the Multispecificity of a Lyngbyatoxin (Indolactam Alkaloid) Nonribosomal Peptide Synthetase

Indolactam alkaloids are activators of protein kinase C (PKC) and are of pharmacological interest for the treatment of pathologies involving PKC dysregulation. The marine cyanobacterial nonribosomal peptide synthetase (NRPS) pathway for lyngbyatoxin biosynthesis, which we previously expressed in E. coli, was studied for its amenability towards the biosynthesis of indolactam variants. Modification of culture conditions for our E. coli heterologous expression host and analysis of pathway products suggested the native lyngbyatoxin pathway NRPS does possess a degree of relaxed specificity. Site-directed mutagenesis of two positions within the adenylation domain (A-domain) substrate-binding pocket was performed, resulting in an alteration of substrate preference between valine, isoleucine, and leucine. We observed relative congruence of in vitro substrate activation by the LtxA NRPS to in vivo product formation. While there was a preference for isoleucine over leucine, the substitution of alternative tailoring domains may unveil the true in vivo effects of the mutations introduced herein.     

Adenosine triphosphate-dependent transport of anionic conjugates by the rabbit multidrug resistance-associated protein Mrp2 expressed in insect cells

The multidrug resistance-associated protein Mrp2 is expressed in liver, kidney, and small intestine and mediates ATP-dependent transport of conjugated organic anions across the apical membrane of epithelial cells. We recently cloned a rabbit cDNA encoding a protein that on basis of highest amino acid homology and tissue distribution was considered to be the rabbit homolog of rat Mrp2. To investigate whether rabbit Mrp2 mediates ATP-dependent transport similar to rat Mrp2, we expressed rabbit Mrp2 in Spodoptera frugiperda (Sf9) cells using recombinant baculovirus. Mrp2 was expressed as an underglycosylated protein in Sf9 cells and to a higher level compared with rabbit liver and renal proximal tubules. Both 17beta-estradiol-17-beta-D-glucuronide ([3H]E217betaG, 50 nM) and [3H]leukotriene C4 (3 nM) were taken up by Sf9-Mrp2 membrane vesicles in an ATP-dependent fashion. Uptake of [3H]E217betaG was dependent on the osmolarity of the medium and saturable for ATP (Km = 623 microM). Leukotriene C4, MK571, phenolphthalein glucuronide, and fluorescein-methotrexate were good inhibitors of [3H]E217betaG transport. The inhibitory potency of cyclosporin A and methotrexate was moderate, whereas fluorescein, alpha-naphthyl-beta-D-glucuronide, and p-nitrophenyl-beta-D-glucuronide did not inhibit transport. In conclusion, we show direct ATP-dependent transport by recombinant rabbit Mrp2 and provide new data on Mrp2 inhibitor specificity.