Sperm chemotaxis occurs widely in animals and plants and plays an important role in the success of fertilization. Several studies have recently demonstrated that Ca(2+) influx through specific Ca(2+) channels is a prerequisite for sperm chemotactic movement. However, the regulator that modulates flagellar movement in response to Ca(2+) is unknown. Here we show that a neuronal calcium sensor, ca...

As axons elongate, tubulin, which is synthesized in the cell body, must be transported and assembled into new structures in the axon. The mechanism of transport and the location of assembly are presently unknown. We report here on the use of tubulin tagged with a photoactivatable fluorescent group to investigate these issues. Photoactivatable tubulin, microinjected into frog embryos at the two-...

Remarkably, forces within a neuron can extend its axon to a target that could be meters away. The two main cytoskeleton components in neurons are microtubules, which are mostly bundled along the axon shaft, and actin filaments, which are highly enriched in a structure at the axon distal tip, the growth cone. Neurite extension has been thought to be driven by a combination of two forces: pushing...

In this paper, the method of robust sliding mode control for a class of switched neutral control systems with mismatched fractional form parametric uncertainties is investigated. A delay-dependent sufficient condition for the existence of linear sliding surfaces is given in term of linear matrix inequality(LMI), and sliding mode controllers based on reaching law are developed, which are to ensu...

An Integral Nested Sliding Mode Control (INSMC) is proposed for n-link robotic manipulators tracking problem by employing Integral Sliding Mode (ISM) and Nested Sliding Mode (NSM) concepts. This controller has the robustness of NSM against matched and no matched perturbations, and the capability of ISM to reduce the sliding functions gains. Application to a two-link planar robot manipulator is ...

Sliding mode control is introduced into classical model free fuzzy logic control for discrete time nonlinear systems with uncertainty to the design of a novel fuzzy sliding mode control to meet the requirement of necessary and sufficient reaching conditions of sliding mode control. The simulation results show that the proposed controller outperforms the original fuzzy sliding mode controller an...

As we know, sliding mode control methodology is one of the robust control technique to handle systems with model uncertainties, parameter variations and external disturbances. In this paper, a robust altitude control scheme is proposed for a nonlinear quad-rotor aircraft system based on sliding mode controller with an integral action to eliminate the steady-state error effect. The proposed slid...

The interlayer sliding potential of multilayered hexagonal boron nitride (h-BN) and graphene is investigated using density-functional theory including many-body van der Waals (vdW) interactions. We find that interlayer sliding constraints can be employed to tune the contribution of electrostatic interactions and dispersive forces to the sliding energy profile, ultimately leading to different sl...

A hierarchical fuzzy sliding-mode control is proposed to achieve asymptotic stability and favorable decoupling performance. In this approach, the nonlinear system is decoupled into several subsystems and the state response of each subsystem can be designed to be governed by a corresponding sliding surface. Then the whole system is controlled by a hierarchical sliding-mode controller. The propos...

Using the singularity theory of scalar functions, we derive a classification of sliding bifurcations in piecewise-smooth flows. These are global bifurcations which occur when distinguished orbits become tangent to surfaces of discontinuity, called switching manifolds. The key idea of the paper is to attribute sliding bifurcations to singularities in the manifold’s projection along the flow, nam...