Acoustic Radiation Force and Torque on Small Particles as Measures of the Canonical Momentum and Spin Densities.

We examine acoustic radiation force and torque on a small (subwavelength) absorbing isotropic particle immersed in a monochromatic (but generally inhomogeneous) sound-wave field. We show that by introducing the monopole and dipole polarizabilities of the particle, the problem can be treated in a way similar to the well-studied optical forces and torques on dipole Rayleigh particles. We derive simple analytical expressions for the acoustic force (including both the gradient and scattering forces) and torque. Importantly, these expressions reveal intimate relations to the fundamental field properties introduced recently for acoustic fields: the canonical momentum and spin angular momentum densities. We compare our analytical results with previous calculations and exact numerical simulations. We also consider an important example of a particle in an evanescent acoustic wave, which exhibits the mutually orthogonal scattering (radiation-pressure) force, gradient force, and torque from the transverse spin of the field.

Plasmonic and silicon spherical nanoparticle antireflective coatings.

Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.

[Rehabilitation of schizophrenic patients with a protracted course under usual industrial conditions]. / Reabilitatsiia bol'nykh s zatiazhnym techeniem shizofrenii v usloviiakh obychnogo proizvodstva

The authors studied the effectively of rehabilitation in 220 patients with a protracted course of the schizophrenic process in individually created conditions, at a usual industrial plant and in conditions of state farms. The clinical observations and dispersed analysis detected that there are multifold correlations between different clinical factors and the effectiveness of rehabilitation. The authors have their opinion concerning the necessity of elaborating differentiated clinical indications to the rehabilitation of schizophrenic patients with a prologned continuous stay in a hospital. According to 2-year following up the general outcome of rehabilitation was evaluated as favourable in 69%. These data permit to expand the present concept of the clinical and social prognosis in protracted forms of schizophrenia.