Orientation by helical motion—II. Changing the direction of the axis of motion

1993 ◽  
Vol 55 (1) ◽  
pp. 213-230 ◽  
Author(s):  
H CRENSHAW ◽  
L EDELSTEINKESHET
Keyword(s):  
2021 ◽  
Author(s):  
Jiaxin Hou ◽  
Anirban Mondal ◽  
Guiying Long ◽  
Laurens de Haan ◽  
Wei Zhao ◽  
...  

2015 ◽  
Vol 92 (1) ◽  
Author(s):  
Andreas Kaiser ◽  
Katarina Popowa ◽  
Hartmut Löwen
Keyword(s):  

2021 ◽  
Vol 1018 ◽  
pp. 105-110
Author(s):  
Jiang Nan Liu ◽  
Yan Hua Zou

In this study, mainly researching the improvement of roundness of thick SUS304 stainless steel tube by interior magnetic abrasive finishing using a magnetic machining jig. The influence of reciprocating velocity of magnetic pole unit on the improvement of roundness of interior surface was studied by establishing the dynamic equation of magnetic machining jig. Experimental results showed that low reciprocating velocity of magnetic pole unit is conducive to the improvement of interior roundness of the thick SUS304 stainless steel tube. The reason is that the low reciprocating velocity of magnetic pole unit reduces the pitch of the helical motion and can produce greater finishing force of the magnetic machining jig.


2001 ◽  
Vol 204 (17) ◽  
pp. 2959-2973 ◽  
Author(s):  
Matthew J. McHenry

SUMMARY A great diversity of unicellular and invertebrate organisms swim along a helical path, but it is not well understood how asymmetries in the body shape or the movement of propulsive structures affect a swimmer’s ability to perform the body rotation necessary to move helically. The present study found no significant asymmetries in the body shape of ascidian larvae (Distaplia occidentalis) that could operate to rotate the body during swimming. By recording the three-dimensional movement of free-swimming larvae, it was found that the tail possessed two bends, each with constant curvature along their length. As these bends traveled posteriorly, the amplitude of curvature changes was significantly greater in the concave-left direction than in the concave-right direction. In addition to this asymmetry, the tail oscillated at an oblique angle to the midline of the trunk. These asymmetries generated a yawing moment that rotated the body in the counterclockwise direction from a dorsal view, according to calculations from hydrodynamic theory. The tails of resting larvae were bent in the concave-left direction with a curvature statistically indistinguishable from the median value for tail curvature during swimming. The flexural stiffness of the tails of larvae, measured in three-point bending, may be great enough to allow the resting curvature of the tail to have an effect on the symmetry of kinematics. This work suggests that asymmetrical tail motion is an important mechanism for generating a yawing moment during swimming in ascidian larvae and that these asymmetries may be caused by the tail’s bent shape. Since helical motion requires that moments also be generated in the pitching or rolling directions, other mechanisms are required to explain fully how ascidian larvae generate and control helical swimming.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Aniruddha Mitra ◽  
Laura Meißner ◽  
Rojapriyadharshini Gandhimathi ◽  
Roman Renger ◽  
Felix Ruhnow ◽  
...  

Abstract Within the mitotic spindle, kinesin motors cross-link and slide overlapping microtubules. Some of these motors exhibit off-axis power strokes, but their impact on motility and force generation in microtubule overlaps has not been investigated. Here, we develop and utilize a three-dimensional in vitro motility assay to explore kinesin-14, Ncd, driven sliding of cross-linked microtubules. We observe that free microtubules, sliding on suspended microtubules, not only rotate around their own axis but also move around the suspended microtubules with right-handed helical trajectories. Importantly, the associated torque is large enough to cause microtubule twisting and coiling. Further, our technique allows us to measure the in situ spatial extension of the motors between cross-linked microtubules to be about 20 nm. We argue that the capability of microtubule-crosslinking kinesins to cause helical motion of overlapping microtubules around each other allows for flexible filament organization, roadblock circumvention and torque generation in the mitotic spindle.


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