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Colonies of bacterial cells can display complex collective dynamics, frequently culminating in the formation of biofilms and other ordered super-structures. Recent studies suggest that to cope with local environmental challenges, bacterial cells can actively seek out small chambers or cavities and assemble there, engaging in quorum sensing behavior. By(More)
The mating pathway in Saccharomyces cerevisiae has been the focus of considerable research effort, yet many quantitative aspects of its regulation still remain unknown. Using an integrated approach involving experiments in microfluidic chips and computational modelling, we studied gene expression and phenotypic changes associated with the mating response(More)
We have analyzed chemotaxis of neutrophil-differentiated HL60 cells in microfluidic devices that create exponential gradients of the chemoattractant, f-Met-Leu-Phe (fMLP). Such gradients expose each cell to a difference in fMLP concentration (DeltaC) across its diameter that is directly proportional to the ambient concentration (C) at that cell's position(More)
We describe the principles of design and the architecture of planar microfluidic networks producing concentration gradients with the shape of any given monotonic function. Each microfluidic network is fed by two separate source solutions and delivers to its outlet a set of N solutions that all differ in concentration. Inside the network, the source(More)
An optofluidic 1x4 switch is designed, fabricated, and tested. The switch is based on a blazed diffraction grating imprinted onto silicone elastomer at the bottom of a microfluidic channel that is filled with liquids with different refractive indices. When the condition of a diffraction maximum is met, the laser beam incident on the grating is deflected by(More)
A microfluidic device that operates as a set of two adaptive cylindrical lenses focusing light along two orthogonal axes is designed, fabricated and characterized. The device is made out of a silicon elastomer, polydimethylsiloxane, using soft lithography, and consists of a few chambers separated by flexible membranes and filled with liquids of different(More)
The taxonomy of treeshrews (Order Scandentia) has long been complicated by ambiguous morphological species boundaries, and the treeshrews of the Palawan faunal region of the Philippines are no exception. Four named forms in the genus Tupaia Raffles, 1821, have been described from four island groups based on subtle qualitative morphological characters, and(More)
This document described the ongoing effort at Goddard Space Flight Center in the TRENDS project to apply advanced technology to the problem of Trend Analysis (TA) of spacecraft. The overall problem of trend analysis is outlined as a case of diagnosis with certain exceptional circumstances. The Model-Based approach to Diagnosis (MBD) and TA is described,(More)
Genetic studies of subspecies endemic to Haida Gwaii (Queen Charlotte Islands), British Columbia and the Alexander Archipelago of southeast Alaska have frequently found genetic corroboration for these phenotypically based taxa. Divergence and speciation are common among island populations of birds, and evidence suggests this region has fostered such(More)
The Philippine Islands are one of the most biologically diverse archipelagoes in the world. Current taxonomy, however, may underestimate levels of avian diversity and endemism in these islands. Although species limits can be difficult to determine among allopatric populations, quantitative methods for comparing phenotypic and genotypic data can provide(More)
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