Erratum: Excitation of terahertz surface plasmons on graphene surfaces by an elementary dipole and quantum emitter: Strong electrodynamic effect of dielectric support [Phys. Rev. B 86, 235440 (2012)]

The excitation of transverse magnetic (TM) surface plasmons by a point dipole in the vicinity of a multilayered graphene/dielectric system is examined. It was previously shown that the surface plasmon (SP) excited by a vertical dipole on an isolated graphene sheet exhibits a strong excitation peak in the THz region; here we show that, in the presence of a finite-thickness dielectric support layer such as SiO 2 , considerable spectral content is transferred to a second (perturbed dielectric slab) mode, greatly decreasing and redshifting the excitation peak. The presence of a Si half-space also diminishes the excitation strength, but for graphene on top of SiO 2 -Si the presence of the SiO 2 layer creates a spacer restoring the excitation peak. A two-level quantum emitter is also considered, where it is shown that the addition of a thin dielectric support slab and SiO 2 -Si geometries affects the spontaneous decay rate in a manner similar to the classical dipole SP excitation peak.

The oxygenation level of a tissue is an important marker of the health of the tissue and has a direct effect on performance. It has been shown that the blood flow to the paretic muscles of hemiparetic post-stroke patients is significantly reduced compared to non-paretic muscles. It is hypothesized that hemodynamic activity in paretic muscles is suppressed as compared to non-paretic muscles, and that oximetry can be used to measure this disparity in real-time. In order to test this hypothesis, a custom-made oximetry device was used to measure hemodynamic activity in the forearm extensor muscles in post-stroke patients’ paretic and non-paretic sides and in a control population during three exercise levels calibrated to the subject’s maximum effort. The change in oxygenation (Δ Oxy ) and blood volume (Δ BV ) were calculated and displayed in real-time. Results show no apparent difference in either Δ Oxy or Δ BV between control subjects’ dominant and non-dominant muscles. However, the results show a significant difference in Δ Oxy between paretic and non-paretic muscles, as well as a significant difference between normalized post-stroke and control data. Further work will be necessary to determine if the observed difference between the paretic and non-paretic muscles changes over the course of physical therapy and can be correlated with functional improvements.