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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Escape Dynamics Of Confined Undulating Worms, Animesh Biswas, Arshad Kudrolli
Escape Dynamics Of Confined Undulating Worms, Animesh Biswas, Arshad Kudrolli
Physics
We investigate the escape dynamics of oligochaeta Lumbriculus variegatus by confining them to a quasi-2D circular chamber with a narrow exit passage. The worms move by performing undulatory and peristaltic strokes and use their head to actively probe their surroundings. We show that the worms follow the chamber boundary with occasional reversals in direction and with velocities determined by the orientation angle of the body with respect to the boundary. The average time needed to reach the passage decreases with its width before approaching a constant, consistent with a boundary-following search strategy. We model the search dynamics as a persistent …
Collective Gradient Sensing In Fish Schools, James G. Puckett, Aawaz R. Pokhrel, Julia A. Giannini
Collective Gradient Sensing In Fish Schools, James G. Puckett, Aawaz R. Pokhrel, Julia A. Giannini
Physics and Astronomy Faculty Publications
Throughout the animal kingdom, animals frequently benefit from living in groups. Models of collective behaviour show that simple local interactions are sufficient to generate group morphologies found in nature (swarms, flocks and mills). However, individuals also interact with the complex noisy environment in which they live. In this work, we experimentally investigate the group performance in navigating a noisy light gradient of two unrelated freshwater species: golden shiners (Notemigonuscrysoleucas) and rummy nose tetra (Hemigrammus bleheri). We find that tetras outperform shiners due to their innate individual ability to sense the environmental gradient. Using numerical simulations, we examine how group performance …
Detection And Counting Of Micro Scale Particles And Pollen Using A Multi-Aperture Coulter Counter, Ashish Jagtiani, Jiang Zhe, Jun Hu, Joan Carletta
Detection And Counting Of Micro Scale Particles And Pollen Using A Multi-Aperture Coulter Counter, Ashish Jagtiani, Jiang Zhe, Jun Hu, Joan Carletta
Joan Carletta
We demonstrate a high throughput, all-electronic Coulter-type sensor with four sensing microapertures to detect and count micro-scale particles. Four particle samples are utilized for this study: polymethacrylate particles 40 µm and 20 µm in diameter, Juniper Scopulorum (Rocky Mountain Juniper) pollen and Cottonwood pollen particles. The two types of pollen particles are roughly 20 µm in diameter. The particles are mixed with deionized water and forced to pass through the microapertures. Voltage pulses across all four apertures are recorded and analysed. Results demonstrate that the sensor can detect and count particles through its four sensing apertures simultaneously. Thus, the counting …
Detection And Counting Of Micro Scale Particles And Pollen Using A Multi-Aperture Coulter Counter, Ashish Jagtiani, Jiang Zhe, Jun Hu, Joan Carletta
Detection And Counting Of Micro Scale Particles And Pollen Using A Multi-Aperture Coulter Counter, Ashish Jagtiani, Jiang Zhe, Jun Hu, Joan Carletta
Dr. Jiang Zhe
We demonstrate a high throughput, all-electronic Coulter-type sensor with four sensing microapertures to detect and count micro-scale particles. Four particle samples are utilized for this study: polymethacrylate particles 40 µm and 20 µm in diameter, Juniper Scopulorum (Rocky Mountain Juniper) pollen and Cottonwood pollen particles. The two types of pollen particles are roughly 20 µm in diameter. The particles are mixed with deionized water and forced to pass through the microapertures. Voltage pulses across all four apertures are recorded and analysed. Results demonstrate that the sensor can detect and count particles through its four sensing apertures simultaneously. Thus, the counting …
Polar Patterns In Active Fluids, Luca Giomi, M. Cristina Marchetti
Polar Patterns In Active Fluids, Luca Giomi, M. Cristina Marchetti
Physics - All Scholarship
We study the spatio-temporal dynamics of a model of polar active fluid in two dimensions. The system exhibits a transition from an isotropic to a polarized state as a function of density. The uniform polarized state is, however, unstable above a critical value of activity. Upon increasing activity, the active fluids displays increasingly complex patterns, including traveling bands, traveling vortices and chaotic behavior. The advection arising from the particles self-propulsion and unique to polar fluids yields qualitatively new behavior as compared to that obtain in active nematic, yielding traveling-wave structures. We show that the nonlinear hydrodynamic equations can be mapped …
Coupled Dynamics Of Voltage And Calcium In Paced Cardiac Cells, Yohannes Shiferaw, Daisuke Sato, Alain Karma
Coupled Dynamics Of Voltage And Calcium In Paced Cardiac Cells, Yohannes Shiferaw, Daisuke Sato, Alain Karma
Alain Karma
We investigate numerically and analytically the coupled dynamics of transmembrane voltage and intracellular calcium cycling in paced cardiac cells using a detailed physiological model and its reduction to a three-dimensional discrete map. The results provide a theoretical framework to interpret various experimentally observed modes of instability ranging from electromechanically concordant and discordant alternans to quasiperiodic oscillations of voltage and calcium.
Assessment Of The Accuracy Of An Ultrasound Elastography Liver Scanning System Using A Pva-Cryogel Phantom With Optimal Acoustic And Mechanical Properties, S. Cournane, Louise Cannon, Jacinta Browne, A. Fagan
Assessment Of The Accuracy Of An Ultrasound Elastography Liver Scanning System Using A Pva-Cryogel Phantom With Optimal Acoustic And Mechanical Properties, S. Cournane, Louise Cannon, Jacinta Browne, A. Fagan
Articles
The accuracy of a transient elastography liver-scanning ultrasound system was assessed using a novel application of PVA-cryogel as a tissue-mimicking material with acoustic and shear elasticity properties optimized to best represent those of liver tissue. Although the liver scanning system has been shown to offer a safer alternative for diagnosing liver cirrhosis through stiffness measurement, as compared to the liver needle biopsy exam, the scanner’s accuracy has not been fully established. The Young’s elastic modulus values of 5-6wt% PVA cryogel phantoms, also containing glycerol and 0.3μm Al2O3 and 3μm Al2O3, were measured using a ‘gold standard’ mechanical testing technique and …