The drag anisotropy of slender filaments is a critical physical property allowing swimming in low-Reynolds number flows, and without it linear translation is impossible. Here we show that, in contrast, net rotation can occur under isotropic drag. We first demonstrate this result formally by considering the consequences of the force- and torque-free conditions on swimming bodies and we then illu...

I briefly review magnetic effects in accretion physics, and then go on to discuss a possible central engine for gamma–ray bursts. A rotating black hole immersed in a non–axisymmetric magnetic field experiences a torque trying to align spin and field. I suggest that gamma–ray burst hosts may provide conditions where this effect allows rapid extraction of a significant fraction of the hole’s rota...

Variable-speed, fixed-pitch wind turbines are required to optimize power output performance without the aerodynamic controls. A wind turbine generator system is operated such that the optimum points of wind rotor curve and electrical generator curve coincide. In order to obtain maximum power output of a wind turbine generator system, it is necessary to drive the wind turbine at an optimal rotor...

high variability in delivering the target torque is reported for friction-style mechanical torque limiting devices (f-s mtlds). the effect of aging (number of use) on the accuracy of these devices is not clear. the purpose of this study was to assess the effect of aging on the accuracy (±10% of the target torque) of f-s mtlds.fifteen new f-s mtlds and their appropriate drivers from three differ...

We investigated the acquisition of skill in balancing a stick (52 cm, 34 g) on the fingertip in nine participants using three-dimensional motion analysis. After 3.5 h of practice over 6 wk, the participants could more consistently balance the stick for longer durations with greatly reduced magnitude and speed of stick and finger movements. Irrespective of level of skill, the balanced stick beha...

Tidal torques play a key role in rotational dynamics of celestial bodies. They govern these bodies’ tidal despinning and also participate in the subtle process of entrapment of these bodies into spin–orbit resonances. This makes tidal torques directly relevant to the studies of habitability of planets and their moons. Our work begins with an explanation of how friction and lagging should be bui...

B-DNA becomes unstable under superhelical stress and is able to adopt a wide range of alternative conformations including strand-separated DNA and Z-DNA. Localized sequence-dependent structural transitions are important for the regulation of biological processes such as DNA replication and transcription. To directly probe the effect of sequence on structural transitions driven by torque, we hav...

accurate delivery of torque to implant screws is critical to generate ideal preload in the screw joint and to offer protection against screw loosening. mechanical torque-limiting devices (mtlds) are available for this reason. in this study, the accuracy of one type of friction-style and two types of spring-style mtlds at baseline, following fatigue conditions and sterilization processes were de...

We study the effect of poloidal magnetic field on type I planetary migration by linear perturbation analysis in the shearing-sheet approximation and the analytic results are compared with numerical calculations. In contrast to the unmagnetized case, the basic equations that describe the wake due to the planet in the disk allow magnetic resonances at which density perturbation diverges. In order...