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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 ...
  • Crouzier, T.; Jang, H.; Ahn, J.; Stocker, Roman; Ribbeck, Katharina (American Chemical Society (ACS), 2013-09)
    The precise spatial control of cell adhesion to surfaces is an endeavor that has enabled discoveries in cell biology and new possibilities in tissue engineering. The generation of cell-repellent surfaces currently requires ...
  • 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 ...
  • Molaei, Mehdi; Barry, Michael; Stocker, Roman; Sheng, Jian (American Physical Society, 2014-08)
    Understanding how bacteria move close to surfaces is crucial for a broad range of microbial processes including biofilm formation, bacterial dispersion, and pathogenic infections. We used digital holographic microscopy to ...
  • 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 ...
  • Rusconi, Roberto; Garren, Melissa S.; Stocker, Roman (Annual Reviews, 2014-05)
    Microfluidics has significantly contributed to the expansion of the frontiers of microbial ecology over the past decade by allowing researchers to observe the behaviors of microbes in highly controlled microenvironments, ...
  • Mayola, Albert; Irazoki, Oihane; Petrov, Dmitri; Menolascina, Filippo; Stocker, Roman; Krell, Tino; Campoy, Susana; Reyes-Darias, Jose A.; Barbe, Jordi; Martinez, Ignacio A. (Public Library of Science, 2014-08)
    The RecA protein is the main bacterial recombinase and the activator of the SOS system. In Escherichia coli and Salmonella enterica sv. Typhimurium, RecA is also essential for swarming, a flagellar-driven surface translocation ...
  • 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, ...
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