Magnetization reversal in a many-spin nanomagnet subjected to an rf magnetic field, on top of DC is studied by numerically solving the system coupled (damped) Landau-Lifshitz equations. It demonstrated that spin-misalignment induced surface anisotropy favors switching with field weaker than Stoner-Wohlfarth for optimal intensities and frequencies field.

A system to measure light scattering from individual cells excited by an acoustic wave was designed, and tests were performed on live Jurkat cells. Cells passing in a laminar stream within a water bath were excited by a focused ultrasound pulse, while the scattered light from a laser beam was monitored at various scattering angles. The cells were modeled as viscoelastic liquid drops, which retu...

We consider a family of damped quasi-Newton methods for solving unconstrained optimization problems. This family resembles that of Broyden with line searches, except that the change in gradients is replaced by a certain hybrid vector before updating the current Hessian approximation. This damped technique modifies the Hessian approximations so that they are maintained sufficiently positive defi...

We obtain an analytic expression for the highly damped asymptotic quasinormal mode frequencies in dimensions d ≥ 5 of the Gauss-Bonnet black hole, which appears in string derived models of gravity. The analytic expression is obtained in the limit when the coupling in front of the Gauss-Bonnet term is small. Although there are several similarities of this geometry with that of the Schwarzschild ...

A quantum system weakly interacting with a fast environment usually undergoes a relaxation with complex frequencies whose imaginary parts are damping rates quadratic in the coupling to the environment, in accord with Fermi’s “Golden Rule”. We show for various models (spin damped by harmonic-oscillator or random-matrix baths, quantum diffusion, quantum Brownian motion) that upon increasing the c...