Multistability and synchronization of chaos in maps with “Internal” coupling

Bifurcation mechanisms responsible for the loss of the complete synchronization of chaos and for formation of multistability in a system with a unidirectional “internal” coupling are considered. The sequence of stages during which chaotic synchronization decays is described. A quantitative analysis of chaotic synchronization is performed.     

Electron transport and detection of terahertz radiation in a GaN/AlGaN submicrometer field-effect transistor

Electron transport and photoresponse in the terahertz range in a GaN/AlGaN field-effect transistor with the submicrometer gate (0.25 μm) and two-dimensional electron gas in the channel (the electron concentration n _s = 5 × 10¹² cm^?2) were studied at 4.2 K. The charge-carrier mobility in the transistor’s channel μ = 3500 cm²/(V s) was determined from the dependence of the conductance on magnetic field. It is found that the dependence of photovoltage at the radiation frequency f = 574 GHz on the gate voltage (i.e., on the concentration of two-dimensional electrons) features a characteristic maximum, which is related to a resonance response of the subgate plasma in the transistor channel.     

A RHEED study of the transition from two-dimensional to three-dimensional growth in the InAs/GaAs system

A specially developed detection system and an analysis of RHEED diffraction patterns were used to investigate the dynamics of transition from two-dimensional to three-dimensional growth mechanism in the heteroepitaxial InAs/GaAs system. An analysis of the dynamics of the diffraction patterns was used for the first time to investigate the dynamics of formation of quantum dots. A time shift in the dynamic behavior of the diffracted intensity for diffraction patterns recorded at different angles was found. This shift is explained in terms of the size differences in the three-dimensional islands at the initial stage of decay of the pseudomorphic layer. InAs/GaAs quantum dots grown under certain conditions produce reflections at 45° relative to the principal reflections. This is evidence for the ordering of islands in the [001] and [010] crystallographic directions. Fiz. Tekh. Poluprovodn. 31, 1230–1232 (October 1997)     

Structure of bismuth films obtained using an array of identically oriented single-crystal bismuth islands preliminarily grown on a substrate

An array of identically oriented single-crystal bismuth islands formed on mica plates is used as a substrate to improve the structure of bismuth thin films grown by vacuum thermal evaporation. The array of islands is formed by the chemical etching of a single-crystal bismuth film 1 μm thick grown by floating-zone recrystallization under a coating. The structure of the obtained films is studied by X-ray diffraction, atomicforce microscopy, and electron backscatter diffraction scanning electron microscopy.     

Dependence of the surface morphology of ultrathin bismuth films on mica substrates on the film thickness

The results of studying the surface of 15- to 100-nm-thick bismuth films by atomic-force microscopy are reported. The near-linear character of the dependences of the average surface roughness and the average height of growth patterns on the film thickness is established. It is found that the average crystallite size increases, as the film thickness is increased. A slight dependence of the crystallite size on the film thickness is observed at thicknesses in the range of 27–70 nm.     

The puncture and catheterization of the peripheral vessels using ultrasonic scanning

1% acetylcholine (5.5 10 M--acetylcholine chloride) applied directly to the cortex of conscious non-immobilized rabbits was established to produce neuroglial reaction in motor area. Following 30 min long application the number of astrocytes was significantly increased. Application lasting for 2 hrs resulted in a reverse effect. The above-mentioned changes were observed in surface and deep cortical layers. They were functional and could be attributed to the cell tinctorial properties.