Econometric predictive model for assessing the functional state of students during the examination period: a cross-sectional exploratory pilot study

Background. Mathematical modeling is widely used in medicine to analyze the body systems in terms of their structure, work and interrelations. The present study investigates factors associated with the adaptation potential of the cardiovascular system, develops multiple regression models for the dependence of the adaptive potential on these factors, and compares the significance of the linear model with non-linear ones. Objectives. To determine changes in the circulatory system in students during the examination period and develop a mathematical model for predicting the adaptive potential of the cardiovascular system. Methods. The cohort observational study enrolled 74 students of Kirov State Medical University, aged 18–23 years, who gave consent to the survey. The participants were divided into two cohorts depending on the dominant type of the autonomic nervous system (group 1 — individuals with the dominance of sympathetic part of the peripheral division of the autonomic nervous system (n = 54) and group 2 — individuals with vagotonic type of regulation (n = 20)). The relationship between the hemodynamic parameters and the initial autonomic tone was considered as the main relevancy criterion of the study. Comparative analysis of hemodynamic parameters depending on the dominant type of autonomic nervous system was carried out in the cohorts. Development of the regression model was based on 74 observations. Data description included median (Me) and interquartile range representing 25th and 75th percentiles. The indicators in independent samples (cohorts) were compared using the non-parametric Mann—Whitney U test. Correlation analysis of relationships between the studied variables involved Spearman’s criterion (r). Differences and correlations were considered significant at p = 0.05. Calculations and analyses were performed using spreadsheets in Statistica Advanced 10 for Windows RU (Statsoft, Russia). Results. The state of the cardiovascular system significantly depends on the dominant type of the autonomic nervous system. Such parameters as stroke volume, cardiac index, cardiac minute output, circulatory efficiency were established to be significantly higher, whereas diastolic blood pressure, mean arterial pressure, cardiovascular index — lower in individuals with activation of the sympathetic part of the autonomic division of the peripheral nervous system. The study revealed significant correlations between the parameters of central hemodynamic and anthropometric parameters depending on the dominant type of the autonomic nervous system. Conclusion. Significant differences of hemodynamic parameters depending on the dominant type of autonomic system indicate the relevance of neurohumoral mechanisms of cardiovascular regulation. The values in adaptive potential exceeded 2.0 points, indicating the stress of the cardiovascular adaptation. The correlation regression analysis showed the greatest significance of the multiple linear regression model developed by the authors for predicting the adaptive potential of the cardiovascular system

Deformation uniformity of additively manufactured materials on the example of austenitic stainless steel 321 and copper C11000

Structural studies and mechanical tests of additively manufactured samples from AISI 321 steel copper C110000 have been carried out. Mechanical tensile tests of 321 steel show slight differences in the ultimate tensile strength (up to 3-4%) and ductility (up to 10%) of test coupons tested along the material growth direction and along the layer deposition direction. The strength of C11000 copper samples is 9.4% higher in the layer deposition direction, but their ductility is 15.4% lower than that of samples deformed in the growth direction. The strain relief on the surface of the polished gage section of the steel test coupons demonstrates changes in the material structure with small elongated grains along the growth direction of the sample. The deformation relief of copper samples is mainly related to the deformation of large columnar grains stretched in the growth direction

Diffusion of barium ions in the Ba3-3xLa2x?x(VO4)2 solid solution

Diffusion coefficients for 133Ba, 90Sr, and 45Ca radionuclides in the solid solution Ba3-3xLa2x?x(VO4)2 (x = 0, 0.05, 0.1, 0.15) are measured in the temperature range 800 to 1000°C using the layer-by-layer radiometric analysis. It is established that Dca* ? DSr? > DBa*. Increasing the concentration of vacancies ? in the barium sublattice leads to an increase in the diffusion coefficients of the alkaline-earth metal cations. The activation energies for the radionuclide diffusion are determined; their values (?1.1 eV) are close to the activation energy for ionic conduction. Cations M2+ are shown to migrate via the positions of Ba(2). © 1999 MAHK "Hayka/Interperiodica Publishing"

Proton induced fission of 232Th at intermediate energies

The mass-energy distributions and cross sections of proton-induced fission of Th-232 have been measured at the proton energies of 7, 10, 13, 20, 40, and 55 MeV. Experiments were carried out at the proton beam of the K-130 cyclotron of the JYFL Accelerator Laboratory of the University of Jyvakyla and U-150m cyclotron of the Institute of Nuclear Physics, Ministry of Energy of the Republic of Kazakhstan. The yields of fission fragments in the mass range A = 60- 170 a.m.u. have been measured up to the level of 10(-4)%. The three humped shape of the mass distribution up has been observed at higher proton energies. The contribution of the symmetric component grows up with increasing proton incident energy; although even at 55 MeV of proton energy the shoulders in the mass energy distribution clearly indicate the asymmetric fission peaks. Evolution of shell structure was observed in the fission fragment mass distributions even at high excitation energy

Abstracts of the 20th annual meeting of the association `Heart - Lung` and 2nd „Varna - Augsburg` conference 30-31 may 2014

Primary tumours of the heart are rare. Metastases are the most frequent tumours of the heart. Anyway, it is generallyagreed that autopsy prevalence of primary cardiac tumors is 1 out of 2,000 and that of secondary cardiactumors is 1 out of 100 autopsies, with a secondary/primary cardiac tumors ratio of 20:1. Cardiac tumors may occurin any cardiac tissue. They can cause valvular or inflow-outflow tract obstruction, thromboembolism, arrhythmias,or pericardial disorders. Symptoms are very variable and can be the result of either local or systemiceffects. Surgery is successful for benign tumours when adequate resection margins are allowed. A number of imagingmodalities are available for the assessment of cardiac tumours; each has advantages and limitations. Thisreport presents our experience in the treatment of tumors of the hear