We propose a mechanism for the initiation of cell motility that is based on myosin-induced contraction and does not require actin polymerization. The translocation induced by symmetry breaking motor-driven flow, ensuing asymmetry gives rise to steady motion center mass cell. predictions model are consistent with observations keratocytes.

Structural vibration controlled by interfacial friction is widespread, ranging from dampers in gas turbines to the motion of violin strings. To predict, control or prevent such vibration, a constitutive description frictional interactions inevitably required. A variety models are discussed assess their scope and validity, light constraints provided different experimental observations. Three contrasting case studies used illustrate how predicted behaviour can be extremely sensitive choice...

The prediction and control of friction-induced vibration requires a sufficiently accurate constitutive law for dynamic friction at the sliding interface: linearised stability analysis, this requirement takes form frictional frequency response function. Systematic measurements function are presented small samples nylon polycarbonate against glass disc. Previous efforts to explain such from theoretical model have failed, but an enhanced rate-and-state is which shown match remarkably well....

Under future CMIP5 climate change scenarios for 2050, an increase in wheat yield of about 10% is predicted Great Britain (GB) as a result the combined effect CO2 fertilization and shift phenology. Compared to present day, crops escape increases impacts drought heat stresses on grain by developing before these can occur. In future, losses from water stress over growing season will remain same across with reaching around 20% potential yield, while flowering decrease account 9% limited yield....

The motility of a cell can be triggered or inhibited not only by an applied force but also mechanically neutral couple. This type loading, represented stress and commonly interpreted as either squeezing stretching, originate from extrinsic interaction with its neighbors. To quantify the effect stresses on we use analytically transparent one-dimensional model accounting for active myosin contraction induced actin turnover. We show that stretching polarize static cells initiate while...

Sliding frictional interfaces at a range of length scales are observed to generate travelling waves; these considered relevant, for example, both earthquake ground surface movements and the performance mechanical brakes dampers. We propose an explanation origins waves through study idealized model: thin elastic plate subject uniform shear stress held in contact with rigid flat surface. construct nonlinear wave equation deformation plate, couple it spinodal rate-and-state friction law which...

Under future CMIP5 climate change scenarios for 2050, an increase in wheat yield of about 10% is predicted Great Britain (GB) as a result the combined effect CO2 fertilization and shift phenology. Compared to present day, crops escape increases impacts drought heat stresses on grain by developing before these can occur. In future, losses from water stress over growing season will remain same across with reaching around 20% potential yield, while flowering decrease account 9% limited yield....

An earthquake is commonly described as a stick-slip frictional instability occurring along preexisting crustal faults. The seismic cycle of recurrence characterized by long periods quasi-static evolution, which precede sudden slip events accompanied elastic wave radiation: the earthquake. This succession processes over two well-distinguished time-scales recalls behavior nonlinear relaxation oscillations. We explore this connection studying, in framework rate-and-state friction, sliding...

We reduce a one-dimensional model of an active segment (AS), which is used, for instance, in the description contraction-driven cell motility, to zero-dimensional particle (AP) characterized by two internal degrees freedom: position and polarity. Both models give rise hysteretic force-velocity relations showing that agent can support opposite polarities under same external force it maintain polarity while being dragged forces with orientations. This double bistability results rich dynamic...

Abstract Neuronal activities underlying a percept are constrained by the physics of sensory signals. In tactile sense such constraints frictional stick–slip events, occurring, amongst other vibrotactile features, when sensors in contact with objects. We reveal new biomechanical phenomena about transmission these microNewton forces at tip rat’s whisker, where they occur, to base engage primary afferents. Using high resolution videography and accurate measurement axial normal follicle, we show...

We develop a quantitative model of mechanical repolarization in contraction-driven gel layer mimicking crawling cell. show that the force-velocity relations for such active crawlers exhibit multi-valuedness and hysteresis under both force velocity control. The predicts steady oscillations cells attached to an elastic environment offers self-consistent explanation all experimentally observed outcomes cell collision tests.

Organic matter amendments appear to increase yield, but need be sustained, as yield decreases when cease. Here we mathematically devise optimal strategies for organic applications that take account of how quickly, in years application, yields build up with and long these benefits persist. The empirical idea a nutrient response curve is used extended include more than single input well the effect yield-enhancing factors such endure one year. Nonlinear regression selection parameter...

The amount of aqueous fluids circulating into the oceanic crust can be estimated using mass balance equations based on stable isotope exchange between rock and water. Unlike oxygen strontium, isotopic trace elements (such as B or Li) rocks, operates along with a chemical evolution rocks (e.g. large enrichment that must integrated any model water-rock interaction. We propose general dimensionless equation for single-pass open systems describes equilibrium elemental distribution composition...