The role of many-body interactions is experimentally and theoretically investigated near the saddle point absorption peak of graphene. The time and energy-resolved differential optical transmission measurements reveal the dominant role played by electron-acoustic phonon coupling in band structure renormalization. Using a Born approximation for electron-phonon coupling and experimental estimates...

Slowly varying conservative one-degree of freedom Hamiltonian systems are analyzed in the case of a saddle-center bifurcation. Away from unperturbed homoclinic orbits, strongly nonlinear oscillations are obtained using the method of averaging. A long sequence of nearly homoclinic orbits is matched to the strongly nonlinear oscillations before and after the slow passage. Usually solutions pass t...

Saddle-fit is recognised as an important factor in the pathogenesis of back problems in horses and is empirically being evaluated by pressure measurements in clinical practice, although not much is known about the validity, reliability and usability of these devices in the equine field. This study was conducted to assess critically a pressure measurement system marketed for evaluating saddle fi...

Different mechanisms for the creation of strange non-chaotic dynamics in the quasiperiodically forced logistic map are studied. These routes to strange nonchaos are characterised through the behavior of the largest nontrivial Lyapunov exponent, as well as through the characteristic distributions of finite time Lyapunov exponents. Strange nonchaotic attractors can be created at a saddle–node bif...

We discuss the excitable behavior of excitons and biexcitons in a nonlinear optical ring cavity. The nonlinearity is due to the process of the creation of biexcitons by photon-assisted conversion of excitons. In the bifurcation analysis a region where a saddle point is close to an equilibrium has been found. In this region the system shows excitability. It is shown that the mechanism of the exc...

We examine the behavior of accelerated gradient methods in smooth nonconvex unconstrained optimization. Each of these methods is typically a linear combination of a gradient direction and the previous step. We show by means of the stable manifold theorem that the heavyball method method does not converge to critical points that do not satisfy second-order necessary conditions. We then examine t...

This paper illustrates transcritical and Hopf bifurcations in a realistic ac/dc power system model. These bifurcations are thoroughly analyzed based on bifurcation theory to understand and characterize their e ect on the dynamic behavior of the system, particularly on voltage stability. A new technique to trace transcritical bifurcations diagrams is proposed, based on the generic characteristic...

The angle of contact between a solid surface and a fluid interface plays a key role in wetting and is therefore a focus in studies of a wide range of natural phenomena and fluidic technologies. The contact angle ranges between two values, a maximum (advancing) angle and a minimum (receding) angle. These limiting angles are thought to be properties of the fluids and of the chemistry or topograph...

The need for mechanical manipulation during the curing of conventional liquid crystal elastomers diminishes their applicability in the field of shape-programmable soft materials and future applications in additive manufacturing. Here we report on polymer-dispersed liquid crystal elastomers, novel composite materials that eliminate this difficulty. Their thermal shape memory anisotropy is imprin...