The oxygen isotope effect on critical temperature in superconducting copper oxides

The isotope effect provided a crucial key to the development of the BCS (Bardeen-Cooper-Schrieffer) microscopic theory of superconductivity for conventional superconductors. In superconducting cooper oxides (cuprates) showing an unconventional type of superconductivity, the oxygen isotope effect is very peculiar: the exponential coefficient strongly depends on doping level. No consensus has been reached so far on the origin of the isotope effect in the cuprates. Here we show that the oxygen isotope effect in cuprates is in agreement with the bisoliton theory of superconductivity.Comment: 3 pages including 4 figures; version 2 is with minor correction

Tonometric estimation of mechanical properties of a cornea and sclera

Purpose: To investigate degree of anisotropy and evaluate elastic constants of the eyeball tissues based on a shell theory. Methods: Simulated sclera was mechanically modeled as an orthotropic spherical shell. Scleral deformations were generated by simulated stresses in the intraocular pressure (IOP). Relations between the shape deflection mode in the shell and the ratio of tangential elasticity modules were calculated. In Maklakov’s method of IOP testing, the eyeball is modelled as two spherical segments with different mechanical properties. The baseline (prior to load) two-segment shell is assumed to be filled with uncompressible liquid under pressure. Young’s module of cornea is much lower than that of sclera. Hence, cornea is more compliant than rigid sclera and doesn’t resist to flexural deformations. A nonlinear shell theory was used to analyze deformations of both the cornea and the sclera. Results: Ratios of tangential elasticity modules of the orthotropic spherical shell in different directions appeared to have a great influence on the amplitude and shape of the deformation in the shell. Therefore, the degree of scleral anisotropy can be evaluated by ratio of anterior-posterior eye axis lengths to the equator diameter. Maklakov’s method of IOP measurement, with several different loads, can be also used to investigate the elasticity of the eye tunics and to study the range of application of physically linear theories of elasticity in mechanical models of pressure-related eyeball deformation. Conclusions: Pressure-related eyeball deformation varies significantly depending on the degree of anisotropy and heterogeneity of the eye tunics. Transversal shear modules have the greatest influence on the pressure-related deformation of the eyeball tunics. Physical nonlinear theories of elasticity are necessary tools to characterize details of pressure-related corneal and scleral deformations

INTENSIFICATION OF MASS TRANSFER WITH CHEMICAL REACTION IN CONDITIONS OF INTERFACIAL CONVECTION FOR SPRAY EXTRACTORS

Studies of mass transfer with a chemical reaction through a spherical interface on a single drop have shown a significant effect of spontaneous interfacial convection on the mass transfer rate

The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft

We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere, arranged by the angle between electric field vector and the projection of spacecraft position radius vector in the YZ plane in MSE coordinate system (${\theta}$ E ). All passes were divided into 3 angular sectors near 0{\deg}, 90{\deg} and 180{\deg} ${\theta}$ E angles in order to estimate the role of IMF direction in plasma and magnetic properties of dayside Martian magnetosphere. The time interval chosen was from January 17 through February 4, 2016 when MAVEN was crossing the dayside magnetosphere at SZA ~ 70{\deg}. Magnetosphere as the region with prevailing energetic planetary ions is always found between the magnetosheath and the ionosphere. 3 angular sectors of dayside interaction region in MSE coordinate system with different orientation of the solar wind electric field vector E = -1/c V x B showed that for each sector one can find specific profiles of the magnetosheath, the magnetic barrier and the magnetosphere. Plume ions originate in the northern MSE sector where motion electric field is directed from the planet. This electric field ejects magnetospheric ions leading to dilution of magnetospheric heavy ions population, and this effect is seen in some magnetospheric profiles. Magnetic barrier forms in front of the magnetosphere, and relative magnetic field magnitudes in these two domains vary. The average height of the boundary with ionosphere is ~530 km and the average height of the magnetopause is ~730 km. We discuss the implications of the observed magnetosphere structure to the planetary ions loss mechanism.Comment: 24 pages, 13 figure

Biomechanical analysis of parameters influencing pressure-volume relationship in the human eye

Purpose: To study the effects of different mechanical properties of the sclera and the cornea, such as their anisotropy, non-uniformity, and deflections in their spherical shapes on pressure-volume relationship. Methods: Correlations between the intraocular pressure (IOP) and the intraocular volume (IOV) were found for spherical and ellipsoidal orthotropic layers by means of 3D-theory of elasticity. Subsequently, the corneoscleral shell of the eye was modeled as a conjugated shell consisting of two segments. The sclera and the cornea are generally assumed to be the parts of the orthotropic elliptic shells with different geometrical and mechanical properties. Relationship between IOP and IOV was obtained for three mechanical models with following problem statements: 1) sclera and cornea are assumed to be soft shells; 2) sclera and cornea are supposedto be orthotropic shells with small modules of elasticity in the thickness direction; for this model calculations were made due to applied shell theory by Chernykh; 3) sclera and cornea are modeled as 3D elastic solids with FEM/ANSYS (ANSYS, Inc.,Canonsburg, PA). The calculations were performed for different sets of parameters for all three mechanical models and were compared to clinical data. Results: Transversal isotropic shells of revolution of different shapes (modelling the sclera) with equal initial volumes showed linear pressure-volume relationship, while proportionality factor (K) is minimal for a spherical shell (emmetropic eye).If the ratio of the axial length (AL) and the equatorial diameter of the shell (D) increases (the case of a shell modelling a myopic eye), then factor K increases up to 5-10%. If the ratio AL/D decreases (for a shell modelling a hyperopic eye), then factorK starkly increases up to 100%. The same effect was observed for the 2-segments model. Conclusions: Both the orthotropic properties of the sclera (the ratio of two tangential modules of elasticity) and the non-uniformity of the sclera have a significant effect on the character of the pressure-volume relationship and, thus, on the rigidity of the human eye. Geometric and elastic properties of the cornea also affect the relationship, although to the less extent

Time-Dependent Invariants for Dirac Equation and Newton-Wigner Position Operator

For Dirac equation, operator-invariants containing explicit time-dependence in parallel to known time-dependent invariants of nonrelativistic Schr\"odinger equation are introduced and discussed. As an example, a free Dirac particle is considered and new invariants are constructed for it. The integral of motion, which is initial Newton-Wigner position operator, is obtained explicitly for a free Dirac particle. For such particle with kick modeled by delta-function of time, the time-depending integral, which has physical meaning of initial momentum, is found.Comment: LATEX,21 pages,submitted to Physica Script