Article records
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A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenFri, 12 Apr 2024 23:44:12 +0000Spirillum swimming: theory and observations of propulsion by the flagellar bundle
https://resolver.caltech.edu/CaltechAUTHORS:20120814-103042801
Authors: {'items': [{'id': 'Winet-H', 'name': {'family': 'Winet', 'given': 'H.'}}, {'id': 'Keller-S-R', 'name': {'family': 'Keller', 'given': 'S. R.'}}]}
Year: 1976
The hydrodynamics and energetics of helical swimming by the bacterium Spirillum sp. is analysed using observations from medium speed cine photomicrography and theory. The photographic records show that the swimming organism's flagellar bundles beat in a helical fashion just as other bacterial flagella do. The data are analysed according to the rotational resistive theory of Chwang & Wu (1971) in a simple-to-use parametric form with the viscous coefficients C_s and C_n calculated according to the method of Lighthill (1975). Results of the analysis show that Spirillum dissipated biochemical energy in performing work against fluid resistance to motion at an average rate of about 6 X 10^(−8) dyne cm s^(-1) with some 62–72% of the power dissipation due to the non-contractile body. These relationships yield a relatively low hydromechanical efficiency which is reflected in swimming speeds much smaller than a representative eukaryote. In addition the C_n/C_s ratio for the body is shown to lie in the range 0–86-1-51 and that for the flagellar bundle in the range 1–46-1-63. The implications of the power calculations for the Berg & Anderson (1973) rotating shaft model are discussed and it is shown that a rotational resistive theory analysis predicts a 5-cross bridge M ring for each flagellum of Spirillum.https://authors.library.caltech.edu/records/5rk5p-90q94A porous prolate-spheroidal model for ciliated micro-organisms
https://resolver.caltech.edu/CaltechAUTHORS:KELjfm77
Authors: {'items': [{'id': 'Keller-S-R', 'name': {'family': 'Keller', 'given': 'Stuart R.'}}, {'id': 'Wu-T-Y-T', 'name': {'family': 'Wu', 'given': 'Theodore Y.'}}]}
Year: 1977
DOI: 10.1017/S0022112077001669
A fluid-mechanical model is developed for representing the mechanism of propulsion of a finite ciliated micro-organism having a prolate-spheroidal shape. The basic concept is the representation of the micro-organism by a prolate-spheroidal control surface upon which certain boundary conditions on the tangential and normal fluid velocities are prescribed. Expressions are obtained for the velocity of propulsion, the rate of energy dissipation in the fluid exterior to the cilia layer, and the stream function of the motion. The effect of the shape of the organism upon its locomotion is explored. Experimental streak photographs of the flow around both freely swimming and inert sedimenting Paramecia are presented and good agreement with the theoretical prediction of the streamlines is found.https://authors.library.caltech.edu/records/8zgs9-7bh34