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Browsing MIT Open Access Articles by Author "Stocker, Roman"

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Browsing MIT Open Access Articles by Author "Stocker, Roman"

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  • Stocker, Roman; Seymour, Justin R.; Ahmed, Tanvir (Oxford University Press, 2009-10)
    Marine bacteria exhibit positive chemotactic responses to the extracellular exudates of the toxic phytoplankton Heterosigma akashiwo. In the environment, this will support bacteria–algae associations with potential ...
  • Marcos; Fu, Henry C.; Powers, Thomas R.; Stocker, Roman (National Academy of Sciences (U.S.), 2012-03)
    The motility of organisms is often directed in response to environmental stimuli. Rheotaxis is the directed movement resulting from fluid velocity gradients, long studied in fish, aquatic invertebrates, and spermatozoa. ...
  • Peruzzo, Paolo; Defina, Andrea; Stocker, Roman; Nepf, Heidi (American Physical Society, 2013-10)
    Surface-piercing vegetation often captures particles that flow on the water surface, where surface tension forces contribute to capture. Yet the physics of capillary capture in flow has not been addressed. Here we model ...
  • Giuffre, Carl; Hinow, Peter; Vogel, Ryan; Ahmed, Tanvir; Stocker, Roman; Consi, Thomas R.; Strickler, J. Rudi (Public Library of Science, 2011-04)
    We study the motility behavior of the unicellular protozoan Paramecium tetraurelia in a microfluidic device that can be prepared with a landscape of attracting or repelling chemicals. We investigate the spatial distribution ...
  • Kindler, Kolja; Khalili, Arzhang; Stocker, Roman (National Academy of Sciences (U.S.), 2010-12)
    Downward carbon flux in the ocean is largely governed by particle settling. Most marine particles settle at low Reynolds numbers and are highly porous, yet the fluid dynamics of this regime have remained unexplored. We ...
  • Stocker, Roman; King, King Yeung; Peacock, Thomas; Torres, Carlos R. (Cambridge University Press, 2009-07)
    We present a combined experimental and numerical investigation of a sphere settling in a linearly stratified fluid at small Reynolds numbers. Using time-lapse photography and numerical modelling, we observed and quantified ...
  • Ramirez Millan, Maria; Caldara, Marina; Rusconi, Roberto; Tarasova, Yekaterina; Stocker, Roman; Ribbeck, Katharina; Billings, Amanda Nicole (Public Library of Science, 2013-08)
    Bacteria within biofilms secrete and surround themselves with an extracellular matrix, which serves as a first line of defense against antibiotic attack. Polysaccharides constitute major elements of the biofilm matrix and ...
  • Sutherland, Kelly R.; Madin, Laurence P.; Stocker, Roman (National Academy of Sciences (U.S.), 2011-08)
    Salps are common in oceanic waters and have higher per-individual filtration rates than any other zooplankton filter feeder. Although salps are centimeters in length, feeding via particle capture occurs on a fine, mucous ...
  • Durham, William McKinney; Climent, Eric; Stocker, Roman (American Physical Society, 2011-06)
    We show that gyrotactic motility within a steady vortical flow leads to tightly clustered aggregations of microorganisms. Two dimensionless numbers, characterizing the relative swimming speed and stability against overturning ...
  • Doostmohammadi, Amin; Stocker, Roman; Ardekani, Arezoo M. (National Academy of Sciences, 2012-02)
    Microorganisms play pivotal functions in the trophic dynamics and biogeochemistry of aquatic ecosystems. Their concentrations and activities often peak at localized hotspots, an important example of which are pycnoclines, ...
  • Stocker, Roman; Doostmohammadi, Amin; Ardekani, Arezoo M. (National Academy of Sciences (U.S.), 2012-02)
    Microorganisms play pivotal functions in the trophic dynamics and biogeochemistry of aquatic ecosystems. Their concentrations and activities often peak at localized hotspots, an important example of which are pycnoclines, ...
  • Marcos; Seymour, Justin R.; Luhar, Mitul; Durham, William M.; Mitchell, James G.; Mackee, Andreas; Stocker, Roman (National Academy of Sciences (U.S.), 2011-02)
    The growth of microbial cultures in the laboratory often is assessed informally with a quick flick of the wrist: dense suspensions of microorganisms produce translucent “swirls” when agitated. Here, we rationalize the ...
  • Lazova, Milena D.; Ahmed, Tanvir; Bellomo, Domenico; Stocker, Roman; Shimizu, Thomas S. (National Academy of Sciences (U.S.), 2011-08)
    Sensory systems rescale their response sensitivity upon adaptation according to simple strategies that recur in processes as diverse as single-cell signaling, neural network responses, and whole-organism perception. Here, ...
  • Stocker, Roman (National Academy of Sciences (U.S.), 2011-02)
    Many bacteria are motile. They use one or more helical flagella as propellers, rotating them like the corkscrew on a wine bottle opener. Despite the limited morphological repertoire of the propulsive system, radically ...
  • Powers, Thomas R.; Fu, Henry C.; Stocker, Roman; Marcos (American Physical Society, 2009-04)
    We show that plane parabolic flow in a microfluidic channel causes nonmotile, helically shaped bacteria to drift perpendicular to the shear plane. Net drift results from the preferential alignment of helices with streamlines, ...
  • Stocker, Roman; Ardekani, Arezoo M. (American Physical Society, 2010-08)
    We present fundamental solutions of low Reynolds number flows in a stratified fluid, including the case of a point force (Stokeslet) and a doublet. Stratification dramatically alters the flow by creating toroidal eddies, ...
  • Steger, Doris; Berry, David; Haider, Susanne; Horn, Matthias; Wagner, Michael; Stocker, Roman; Loy, Alexander (Public Library of Science, 2011-08)
    Background The hybridization of nucleic acid targets with surface-immobilized probes is a widely used assay for the parallel detection of multiple targets in medical and biological research. Despite its widespread ...
  • De Lillo, Filippo; Cencini, Massimo; Durham, William M.; Barry, Michael; Stocker, Roman; Climent, Eric; Boffetta, Guido (American Physical Society, 2014-01)
    The motility of microorganisms is often biased by gradients in physical and chemical properties of their environment, with myriad implications on their ecology. Here we show that fluid acceleration reorients gyrotactic ...
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