Dynamics of mechanically induced fiber reorientation in\ud the material reinforced by two families of fibers

The specific fiber alignment and its content in biological tissues are created and maintained by the cells, which respond to mechanical stimuli arising from properties of the surrounding material. This coupling between mechanical anisotropy and tissue remodeling can be modeled in the theory of nonlinear elasticity as a fiber-reinforced hyperelastic material where the remodeling is represented as the change in the fiber orientation and/or amount. Here, we study analytically a simple model of fiber reorientation in a rectangular elastic tissue reinforced by two symmetrically arranged families of fibers subject to constant external loads. In this model, the fiber direction tends to align with the maximum principal stretch. We characterize the global behaviour of the system for all material parameters and applied loads, and show that provided the fibers are tensile initially, the system converges to a stable equilibrium, which corresponds to either complete or intermediate fiber alignment

Baker-Akhiezer Modules on Rational Varieties

The free Baker-Akhiezer modules on rational varieties obtained from ${\mathbb C}P^{1}\times{\mathbb C}P^{n-1}$ by identification of two hypersurfaces are constructed. The corollary of this construction is the existence of embedding of meromorphic function ring with some fixed pole into the ring of matrix differential operators in $n$ variables

Detection of Rs9939609 Polymorphism of Fto Gene and Rs324011 Polymorphism of Stat6 Gene and Severity Degree of Bronchial Asthma Associated with Obesity

The aim of this research was to analyze the distribution of FTO and STAT6 genes polymorphism in patients with bronchial asthma (BA), associated with obesity (Ob) depending on the main disease severity degree.Materials and methods. The study included 117 patients 18–48 years old, divided in 3 groups. The main group (bronchial asthma, associated with obesity) included 57 patients, two groups of comparison – 30 patients with the diagnosis BA and a normal body weight, and 30 patients with obesity, but without the pathology of the bronchopulmonary system.The general genomic DNA was extracted from blood according to the standard protocol. The genetic typing was realized by the method of allele-specific amplification with the detection of results in the real time regime using TaqMan-probes, complementary to polymorphic parts of DNA. The detection of deletions in FTO and STAT 6 genes was realized by the method of polymerase chain reaction (PCR) using specific primers.Results. In the main group, among patients with BA and Ob, carriers of Т/Т genotype were 36,84 %, Т/А – 45,61 %, А/А – 17,55 % against 40 %, 60 % and 0 % respectively in PHP group by FTO gene. Carriers of С/С genotype in the main group were 38,6 %, С/Т – 35,09 %, Т/Т – 26,31 % against 40 %, 55 % and 5 % respectively in PHP group by STAT6 gene. In the main group the light persisting BA was diagnosed in 20,0 % of cases, middle severity – in 60,0 % and severe – in 20,0 % of patients. In the group of comparison this disease severity was observed in 17,7 %, 66,5 % and 15,8 % of observations, respectively.Conclusions. So, among patients with BA, associated with Ob with the middle and severe course of asthma the percent of heterozygous (Т/А) and mutant carriers (А/А) rs9939609 polymorphism of FTO gene is higher than at the light course. The analogous situation is observed at the study of rs324011 polymorphism of STAT6 (C2892T) gene among this category of patients. So, the determination of FTO and STAT6 genes polymorphism in patients with BA, associated with Ob, can be considered as a marker of the more severe course of asthma

An experimental investigation of a two and a three-dimensional low speed turbulent boundary layer

Experimental studies of a two and a three-dimensional low speed turbulent boundary layer were conducted on the side wall of a boundary layer wind tunnel. The 20 ft. long test section, with a rectangular cross section measuring 17.5 in. x 46 in., produced a 3.5 in. thick turbulent boundary layer at a free stream Reynolds number. The three-dimensional turbulent boundary layer was produced by a 30 deg swept wing-like model faired into the side wall of the test section. Preliminary studies in the two-dimensional boundary layer indicated that the flow was nonuniform on the 46 in. wide test wall. The nonuniform boundary layer is characterized by transverse variations in the wall shear stress and is primarily caused by nonuniformities in the inlet damping screens

Coupled thermomechanical dynamics of phase transitions in shape memory alloys and related hysteresis phenomena

In this paper the nonlinear dynamics of shape memory alloy phase transformations is studied with thermomechanical models based on coupled systems of partial differential equations by using computer algebra tools. The reduction procedures of the original model to a system of differential-algebraic equations and its solution are based on the general methodology developed by the authors for the analysis of phase transformations in shape memory materials with low dimensional approximations derived from center manifold theory. Results of computational experiments revealing the martensitic-austenitic phase transition mechanism in a shape-memory-alloy rod are presented. Several groups of computational experiments are reported. They include results on stress- and temperature-induced phase transformations as well as the analysis of the hysteresis phenomenon. All computational experiments are presented for Cu-based structures