Cluster structure of the material surface as the cause of the selective enhancement of ultracold-neutron capture associated with subbarrier reflection

Neutron-radiation analysis is used to investigate the subbarrier reflection of ultracold neutrons from the surface of a titanium-stabilized Fe-Ni-Cr stainless steel. A significant selective increase in the probability of neutron capture by nuclei of the medium in comparison to theory is discovered. An explanation is given for the effect, which is associated with the existence of titanium-containing clusters and structural defects that distort the form of the distribution of the effective interaction potential between ultracold neutrons and the material surface. Zh. éksp. Teor. Fiz. 115, 126–140 (January 1999)     

Degenerate Reflections in Acoustics of Solids. III: Cubic Crystals

Crystallography Reports - Particular cases of reflection of bulk acoustic waves from a free surface of cubic crystal, when both the plane of incidence and the crystal surface are symmetry planes,...     

Acoustic Modes at the Twist Boundary in Piezoelectric Crystals

The transformations of the shear (SH and SV) and longitudinal (L) acoustic waves at the twist boundary in piezoelectrics of ?62m and ?42m the and classes have been investigated. This boundary is formed at a hard contact between two identical crystal half-spaces rotated relative to each other around the Z||?6||?4 axis by an angle 2?. Propagation occurs along the bisector of this angle (х axis) in the (x, y) twist plane. Situations have been established in which the shear modes are localized at the twist boundary exclusively due to the combination of the piezoelectric effect and half-space rotation, as well as the joint effect of the elastic anisotropy and rotation. The cases of independence of a bulk wave of the half-space rotation and occurrence of leaky waves are described.     

Soret-driven convection of binary mixture in a horizontal porous layer in the presence of a heat or concentration source

Soret-driven convection of a binary mixture in a shallow porous layer is analyzed. The analysis focuses on the behavior of the system in the presence of a concentration or heat source. In the long-wavelength limit, regimes are found in which the flow regions near the source and at the periphery are separated by narrow annular transition regions. It is also shown that the outward concentration flux from the source is dominated by convection, whereas heat can be transferred from the source both by convection and by diffusion. Multistability between these two regimes is possible.     

Coherent influence of RF field on the gamma-optical properties of a medium upon crossing-anticrossing of nuclear levels

A new approach to the observation of electromagnetic-induced transparency in gamma optics is proposed. For this purpose, the propagation of a resonant gamma photon in a ⁵⁷Fe magnetic medium affected by an external radiofrequency (RF) field is considered. It is demonstrated that, in the case of crossing-anticrossing, a resonant RF field significantly transforms gamma-optical properties of the medium that become dependent on its parameters. This allows coherent control of the group velocity of gamma photons and controlled filtering of unpolarized gamma radiation in the sample to be realized.     

Mathematical modeling of Maklakoff’s method for measuring the intraocular pressure

The physical content of Maklakoffs tonometric (based on the loading of the cornea) method of measuring the intraocular pressure, widely used in medical practice, is discussed. For this purpose, we employ both the results of physical modeling of the eye described in the literature and the results of our own mathematical modeling based on the representation of the eyeball as a thin shell. The effect of the physical properties of the shell on the results of the modeling is investigated. Qualitative conclusions that follow from our study and may be of practical interest in measuring the intraocular pressure are discussed.__________Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, 2005, pp. 24–39. Original Russian Text Copyright © 2005 by Bauer, Lyubimov, and Tovstik.