Engineering Commons^™

Quantitative Elucidation Of A Distinct Spatial Gradient-Sensing Mechanism In Fibroblasts, Ian C. Schneider, Jason M. Haugh

Ian C. Schneider

Migration of eukaryotic cells toward a chemoattractant often relies on their ability to distinguish receptor-mediated signaling at different subcellular locations, a phenomenon known as spatial sensing. A prominent example that is seen during wound healing is fibroblast migration in platelet-derived growth factor (PDGF) gradients. As in the well-characterized chemotactic cells Dictyostelium discoideum and neutrophils, signaling to the cytoskeleton via the phosphoinositide 3-kinase pathway in fibroblasts is spatially polarized by a PDGF gradient; however, the sensitivity of this process and how it is regulated are unknown. Through a quantitative analysis of mathematical models and live cell total internal reflection fluorescence microscopy …

Genetic Programming For Multitimescale Modeling, Kumara Sastry, Duane D. Johnson, David E. Goldberg, Pascal Bellon

Duane D. Johnson

A bottleneck for multitimescale thermally activated dynamics is the computation of the potential energy surface. We explore the use of genetic programming (GP) to symbolically regress a mapping of the saddle-point barriers from only a few calculated points via molecular dynamics, thereby avoiding explicit calculation of all barriers. The GP-regressed barrier function enables use of kinetic Monte Carlo to simulate real-time kinetics (seconds to hours) based upon realistic atomic interactions. To illustrate the concept, we apply a GP regression to vacancy-assisted migration on a surface of a concentrated binary alloy (from both quantum and empirical potentials) and predict the diffusion …

Spatial Analysis Of 3′ Phosphoinositide Signaling In Living Fibroblasts, Iii: Influence Of Cell Morphology And Morphological Polarity, Ian C. Schneider, Elizabeth M. Parrish, Jason M. Haugh

Ian C. Schneider

Activation of phosphoinositide (PI) 3-kinase is a required signaling pathway in fibroblast migration directed by platelet-derived growth factor. The pattern of 3′ PI lipids in the plasma membrane, integrating local Pl 3-kinase activity as well as 3′ PI diffusion and turnover, influences the spatiotemporal regulation of the cytoskeleton. In fibroblasts stimulated uniformly with platelet-derived growth factor, visualized using total internal reflection fluorescence microscopy, we consistently observed localized regions with significantly higher or lower 3′ PI levels than adjacent regions (hot and cold spots, respectively). A typical cell contained multiple hot spots, coinciding with apparent leading edge structures, and at most …

Genome-Wide Requirements For Resistance To Functionally Distinct Dna-Damaging Agents, Patrick Flaherty

Patrick Flaherty

A Latent Variable Model For Chemogenomic Profiling, Patrick Flaherty

Patrick Flaherty

Predicted Gait Modifications To Reduce The Peak Knee Adduction Torque, B. J. Fregly, K. L. Rooney, Jeffrey A. Reinbolt

Jeffrey A. Reinbolt

No abstract provided.

Creation Of Patient-Specific Dynamic Models From Three-Dimensional Movement Data Using Optimization, Jeffrey A. Reinbolt, B. J. Fregly

Jeffrey A. Reinbolt

No abstract provided.

Elastic Waves Push Organic Fluids From Reservoir Rock, Igor A. Beresnev, R. Dennis Vigil, Wenqing Li, Wayne D. Pennington, Roger M. Turpening, Pavel P. Iassonov, Robert P. Ewing

R. Dennis Vigil

Elastic waves have been observed to increase productivity of oil wells, although the reason for the vibratory mobilization of the residual organic fluids has remained unclear. Residual oil is entrapped as ganglia in pore constrictions because of resisting capillary forces. An external pressure gradient exceeding an ‘‘unplugging’’ threshold is needed to carry the ganglia through. The vibrations help overcome this resistance by adding an oscillatory inertial forcing to the external gradient; when the vibratory forcing acts along the gradient and the threshold is exceeded, instant ‘‘unplugging’’ occurs. The mobilization effect is proportional to the amplitude and inversely proportional to the …

Regional Osteoporosis In The Spinal Cord Of Disabled War Veterans, Hossein Gholizadeh

Hossein Gholizadeh

Introduction: Osteoporosis, the result of an imbalance between bone resorption and bone formation, is a potential problem for patients with spinal cord injury (SCI) because of immobility commonly associated with this impairment. Bone mineral content decreases by 25% to 50% and the magnitude of this reduction is dependent on the level, completeness and duration of SCI. This study was designed to evaluate osteoporosis in war veterans with SCI in Isfahan province. Methods: In this cross-sectional study, by use of a cluster sampling frame, SCI veterans underwent-dualenergy X-ray absorptiometry (DEXA) to define bone mineral density (BMD) in 2nd to 4th lumbar …

Evaluation Of The Particle Swarm Algorithm For Biomechanical Optimization, J. F. Schutte, B. I. Koh, Jeffrey A. Reinbolt, B. J. Fregly, R. T. Haftka, A. D. George

Jeffrey A. Reinbolt

Optimization is frequently employed in biomechanics research to solve system identification problems, predict human movement, or estimate muscle or other internal forces that cannot be measured directly. Unfortunately, biomechanical optimization problems often possess multiple local minima, making it difficult to find the best solution. Furthermore, convergence in gradient-based algorithms can be affected by scaling to account for design variables with different length scales or units. In this study we evaluate a recentlydeveloped version of the particle swarm optimization (PSO) algorithm to address these problems. The algorithm’s global search capabilities were investigated using a suite of difficult analytical test problems, while …

Inkjet Printing Of Viable Mammalian Cells, Tao Xu, Joyce Jin, Cassie Gregory, Jay Hickman, Thomas Boland

Thomas Boland

The purpose of this study was to explore the use of a commercial thermal printer to deposit Chinese Hamster Ovary (CHO) and embryonic motoneuron cells into pre-defined patterns. These experiments were undertaken to verify the biocompatibility of thermal inkjet printing of mammalian cells and the ability to assemble them into viable constructs. Using a modified Hewlett Packard (HP) 550C computer printer and an HP 51626a ink cartridge, CHO cells and rat embryonic motoneurons were suspended separately in a concentrated phosphate buffered saline solution (3 x). The cells were subsequently printed as a kind of "ink" onto several "bio-papers" made from …

Advances In Tissue Engineering: Cell Printing, David Varghese, Malay Deshpande, Priya Kesari, S Ohri, Thomas Boland

Thomas Boland

No abstract provided.

Bioproduction Of 1,3-Propanediol Dehydrogenase – A Preliminary Overview, Chuen-Tat Kang

Kang Chuen Tat (江俊达)

Overall rate of bioproduction in 1,3-propanediol dehydrogenase, an enzyme that catalyse the synthesis of the precursor of aromatic high quality plastic, could be affected by preliminary product 3-hydroxypropionaldehyde (HPA) where many structural properties have been summarily analysed via nuclear magnetic resonance (NMR), Fourier Transformed Infrared Spectroscopy (FTIR), High Performance Liquid Chromatography (HPLC), Gas Phase Chromatography (GPC), Scanning Electron Microscopy (SEM). Although the chemical instrumental analysis of the 3-hydroxypropionaldehyde (HPA) may not produce desired result but the data obtained could be useful for future similar analysis that are rare in bulk production. The microbial consumption of various media especially those with …