Morphological Aspects of Diabetic Gastroparesis

The research work highlights issues relating to studying morphological signs of diabetic gastroparesis. On the forty-second day of the development of experimental streptozotocin-induced diabetes mellitus neuronal hydropic degeneration confirmed by the results of morphometry and ultrastructural investigations was observed in the intermuscular plexus of the rats’ stomach. Pycnomorphous cells were found. Axonal degeneration defining the neurogenic nature of the damage to unmyelinated nerve fibers was also present. The processes of apoptosis were initiated in the interstitial cells of Cajal leading to their death. Such changes occurred on the background of the development of diabetic microangiopathy which caused pronounced destructive changes in the smooth myocytes resulting in the violation of their contractility due to circulatory and hemic hypoxias. Thus, experimental diabetes mellitus in rats changes motor-evacuation function of the stomach by destructive changes in the myogenic and neurogenic factors regulating it.

Emergence of anisotropic Gilbert damping in ultrathin Fe layers on GaAs (001)

As a fundamental parameter in magnetism, the phenomenological Gilbert damping constant a determines the performance of many spintronic devices. For most magnetic materials, a is treated as an isotropic parameter entering the Landau-Lifshitz-Gilbert equation. However, could the Gilbert damping be anisotropic? Although several theoretical approaches have suggested that anisotropic a could appear in single-crystalline bulk systems, experimental evidence of its existence is scarce. Here, we report the emergence of anisotropic magnetic damping by exploring a quasi-two-dimensional single-crystalline ferromagnetic metal/semiconductor interface-that is, a Fe/GaAs(001) heterojunction. The observed anisotropic damping shows twofold C-2v symmetry, which is expected from the interplay of interfacial Rashba and Dresselhaus spin-orbit interaction, and is manifested by the anisotropic density of states at the Fe/GaAs (001) interface. This discovery of anisotropic damping will enrich the understanding of magnetization relaxation mechanisms and can provide a route towards the search for anisotropic damping at other ferromagnetic metal/semiconductor interfaces

On estimating the stability of linear parametric circuits during frequency symbol analysis

In the article the possibility of estimating asymptotic stability of linear parametric circuits during frequency symbolic analysis and approximation of the circuit's transfer function by truncated Fourier series is considered. Estimate of asymptotic stability is conducted on the basis of normal, not the bi-frequency, transfer function as in the usual case. An example of estimating asymptotic stability of a single-contour parametric amplifier is provided

Magnetic interactions in NiO at ultrahigh pressure

Magnetic properties of NiO have been studied in the multimegabar pressure range by nuclear forward scattering of synchrotron radiation using the 67.4 keV Mössbauer transition of Ni61. The observed magnetic hyperfine splitting confirms the antiferromagnetic state of NiO up to 280 GPa, the highest pressure where magnetism has been observed so far, in any material. Remarkably, the hyperfine field increases from 8.47 T at ambient pressure to ∼24 T at the highest pressure, ruling out the possibility of a magnetic collapse. A joint x-ray diffraction and extended x-ray-absorption fine structure investigation reveals that NiO remains in a distorted sodium chloride structure in the entire studied pressure range. Ab initio calculations support the experimental observations, and further indicate a complete absence of Mott transition in NiO up to at least 280 GPa