New Mathematical Model of Electromechanical Coupling in Rat Cardiomyocytes

The rat is one of the most widely used laboratory animal species. Therefore development of mathematical models aimed to analyze electromechanical coupling in the rat myocardium is a matter of top interest. We have developed a novel model of excitation-contraction coupling in the rat cardiomyocyte. This model combines equations from the Pandit electrophysiological model and Hinch model of calcium handling with equations describing myofilament mechanical activity from the 'Ekaterinburg-Oxford' mathematical model. The model reproduces both fast and slow responses to mechanical interventions in rat myocardium. © 2018 Creative Commons Attribution.Russian Foundation for Basic Research, RFBR: 18-01-00059The work is performed in the frameworks of IIP UrB RAS projects (Nos. AAAA-A18-118020590031-8, АААА-А18-118020590134-6), and supported by RFBR (No. 18-01-00059), by Act 211 Government of the Russian Federation, contract No. 02.A03.21.0006

The Effects of Mechanical Preload on Transmural Differences in Mechano-Calcium-Electric Feedback in Single Cardiomyocytes: Experiments and Mathematical Models

Transmural differences in ventricular myocardium are maintained by electromechanical coupling and mechano-calcium/mechano-electric feedback. In the present study, we experimentally investigated the influence of preload on the force characteristics of subendocardial (Endo) and subepicardial (Epi) single ventricular cardiomyocytes stretched by up to 20% from slack sarcomere length (SL) and analyzed the results with the help of mathematical modeling. Mathematical models of Endo and Epi cells, which accounted for regional heterogeneity in ionic currents, Ca2+ handling, and myofilament contractile mechanisms, showed that a greater slope of the active tension–length relationship observed experimentally in Endo cardiomyocytes could be explained by greater length-dependent Ca2+ activation in Endo cells compared with Epi ones. The models also predicted that greater length dependence of Ca2+ activation in Endo cells compared to Epi ones underlies, via mechano-calcium-electric feedback, the reduction in the transmural gradient in action potential duration (APD) at a higher preload. However, the models were unable to reproduce the experimental data on a decrease of the transmural gradient in the time to peak contraction between Endo and Epi cells at longer end-diastolic SL. We hypothesize that preload-dependent changes in viscosity should be involved alongside the Frank–Starling effects to regulate the transmural gradient in length-dependent changes in the time course of contraction of Endo and Epi cardiomyocytes. Our experimental data and their analysis based on mathematical modeling give reason to believe that mechano-calcium-electric feedback plays a critical role in the modulation of electrophysiological and contractile properties of myocytes across the ventricular wall. © Copyright © 2020 Khokhlova, Konovalov, Iribe, Solovyova and Katsnelson.AAAA-A18-118020590031-8Russian Foundation for Basic Research, RFBR: 18-01-00059Russian Science Foundation, RSF: 18-74-10059Funding. Wet experiments were supported by the Russian Science Foundation (#18-74-10059). The development of mouse ventricular cardiomyocyte model was supported by the Russian Foundation for Basic Research (#18-01-00059), IIF UrB RAS theme (AAAA-A18-118020590031-8), and by RF Government Act #211 of March 16, 2013 (agreement 02.A03.21.0006)

Effect of an electric field on superfluid helium scintillation produced by alpha-particle sources

We report a study of the intensity and time dependence of scintillation produced by weak alpha particle sources in superfluid helium in the presence of an electric field (0 - 45 kV/cm) in the temperature range of 0.2 K to 1.1 K at the saturated vapor pressure. Both the prompt and the delayed components of the scintillation exhibit a reduction in intensity with the application of an electric field. The reduction in the intensity of the prompt component is well approximated by a linear dependence on the electric field strength with a reduction of 15% at 45 kV/cm. When analyzed using the Kramers theory of columnar recombination, this electric field dependence leads to the conclusion that roughly 40% of the scintillation results from species formed from atoms originally promoted to excited states and 60% from excimers created by ionization and subsequent recombination with the charges initially having a cylindrical Gaussian distribution about the alpha track of 60 nm radius. The intensity of the delayed component of the scintillation has a stronger dependence on the electric field strength and on temperature. The implications of these data on the mechanisms affecting scintillation in liquid helium are discussed.Comment: 17 pages, 23 figure

Drift of scrollwaves in a mathematical model of a heterogeneous human heart left ventricle

Rotating spiral waves of electrical excitation underlie many dangerous cardiac arrhythmias. The heterogeneity of myocardium is one of the factors that affects the dynamics of such waves. In this paper, we present results of our simulations for scroll wave dynamics in a heterogeneous model of the human left ventricle with analytical anatomically based representation of the geometry and anisotropy. We used a set of 18 coupled differential equations developed by ten Tusscher and Panfilov (TP06 model) which describes human ventricular cells based on their measured biophysical properties. We found that apicobasal heterogeneity dramatically changes the scroll wave dynamics. In the homogeneous model, the scroll wave annihilates at the base, but the moderate heterogeneity causes the wave to move to the apex and then continuously rotates around it. The rotation speed increased with the degree of the heterogeneity. However, for large heterogeneity, we observed formation of additional wavebreaks and the onset of complex spatio-temporal patterns. Transmural heterogeneity did not change the dynamics and decreased the lifetime of the scroll wave with an increase in heterogeneity. Results of our numerical experiments show that the apex may be a preferable location of the scroll wave, which may be important for development of clinical interventions. © 2020 by the authors.AAAA-A18-118020590031-8Russian Foundation for Basic Research, RFBR: 18-29-13008Russian Science Foundation, RSF: 14-35-00005Ural Federal University, UrFUP.K., S.P., O.S., and A.V.P. were funded by the Russian Science Foundation (project 14-35-00005). A.V.P., P.K., and O.S. were funded by the Russian Foundation for Basic Research (#18-29-13008). A.V.P. and O.S. were funded by RF Government Act #211 of 16 March 2013 (agreement 02. A03.21.0006). P.K. and O.S. work was carried out within the framework of the IIF UrB RAS theme No. AAAA-A18-118020590031-8. A.V.P. and H.D. were partially funded by BOF Ghent University. Simulations were performed at the supercomputer Uran of Institute of Mathematics and Mechanics (Ekaterinburg, Russia) and at the supercomputer of Ural Federal University (Ekaterinburg, Russia)

Deformations of the Retaining Structures Upon Deep Excavations in Moscow

Foundation trenches for the buildings having underground floors and vehicular traffic tunnels are excavated in Moscow in congested urban housing environment. A retaining structure is a “slurry wall” made of cast-in-place reinforced concrete), and “soil-mixed-wall”. Retaining structures of trenches are fastened with the help of anchors, metal tie-beams, struts or floor structures. During the monitoring performed at major Moscow construction sites with deep trenches the (NIIOSP) named after Gersevanov created a database on retaining structures deformations

Role of hyperplastic processes of the uterus in infertility at women, employed in metallurgy

То study the role of endometrial hyperplastic processes in the etiopathogenesis of infertility in women, workers of main occupations of metallurgical production. Material and Methods: The examined and treated 147 infertile women, basic trades workers metallurgical plants of Kamensk-Ural, Sverdlovsk region. The control group consisted of 40 healthy women with a history of two or more genera are not working in the industry. Fertility of men in all groups was normal. Age study group ranged from 21 to 44 years (average age 29.4 years). All patients underwent clinical, laboratory, tool, ultrasonography. According to the testimony made colposcopy with cytology and biopsy of the cervix, hysterosalpingography, hysteroscopy with endometrial biopsy or treatment and diagnostic curettage of the uterine cavity, Therapeutic or diagnostic laparoscopy with pathomorphological studies of remote tissues or biopsy material. Surveyed patients were divided as follows: I subgroup - 30 (20,4%) women with primary endocrine sterility, II subgroup - 35 (23,8%) women with primary tubal infertility-endocrine, III subgroup - 31 (21,1 %) women with secondary endocrine infertility and IV of the subgroup was 51 (34,7%) women with secondary tubal infertility endocrine. Results: Videogisteroskopic research and ра№отофЬо!од1са1 study of biopsies obtained by curettage, performed for all patients of the main group by 7-11 days of the menstrual cycle. The detection rate of ЬурефЫгс processes in the endometrium was 15.8%.Цель работы: изучение роли гиперпластических процессов эндометрия в этиопатогенезе бесплодия у женщин, работниц основных профессий металлургического производства. Материал и методы: обследованы и пролечены 147 женщин с бесплодием, работниц основных профессий металлургического производства заводов г.Каменска-Уральского, Свердловской области. Контрольную группу составили 40 здоровых женщин, имеющих в анамнезе двое и более родов, не работающих в металлургии. Фертильность мужей во всех группах была нормальной. Возраст больных основной группы составил от 21 до 44 лет (средний возраст 29,4 лет). Всем больным проведено клиническое, лабораторное, инструментальное, ультразвуковое исследование (УЗИ). По показаниям проведены кольпоскопия с цитологическим исследованием и биопсией шейки матки, гистеросальпингография, гистероскопия с биопсией эндометрия или лечебно-диагностическим выскабливанием полости матки, лечебная или диатостическая лапароскопия с патоморфологическим исследованием удаленных тканей или биопсированного материала. Обследованные больные были разделены следующим образом: I подгруппа-30 (20,4%) женщин с первичным эндокринным бесплодием, II подгруппа - 35 (23,8%) женщин с первичным трубно-эндокринным бесплодием, III подгруппа - 31 (21,1 %) женщина со вторичным эндокринным бесплодием и IV подгруппу составила 51 (34,7%) женщина со вторичным трубно-эндокринным бесплодием. Результаты: видеогистероскопическое исследование и патоморфологическое исследование биогттата, полученного путем юоретажа, проводилось всем пациенткам основной группы на 7-11 дни менструального цикла. Частота выявления гиперпластических процессов в эндометрии составила 15,8%. Выводы: гиперпластические процессы в эндометрии у пациенток с бесплодием, работниц металлургической промышленности, встречаются с частотой 15,8%. Чаще они встречаются у пациенток с первичным трубно-эндокринным бесплодием, преобладает простая железистая гиперплазия эндометрия

Grazing-incidence Small-angle X-ray Scattering Technique for Probing Nanostructures and Processes at Nanoscale

The paper presents the grazing-incidence small-angle X-ray scattering technique and its application to the studies of self-assembly and re-assembly effects of colloidal nanoparticles. Two basic cases are exemplified - solvent evaporation driven self-assembly and self-assembly driven by barrier movement in the Langmuir-Blodgett trough. Studies of the nanoparticle re-assembly effects due to the surfactant removal complete the overview. These examples document strength of GISAXS for an in situ tracking of processes at nanoscale. The results have direct implications for tailored preparation of the self -assembled nanoparticle templates for sensing, plasmonics and other applications

Test beam studies of the TRD prototype filled with different gas mixtures based on Xe, Kr, and Ar

Towards the end of LHC Run1, gas leaks were observed in some parts of the Transition Radiation Tracker (TRT) of ATLAS. Due to these leaks, primary Xenon based gas mixture was replaced with Argon based mixture in various parts. Test-beam studies with a dedicated Transition Radiation Detector (TRD) prototype were carried out in 2015 in order to understand transition radiation performance with mixtures based on Argon and Krypton. We present and discuss the results of these test-beam studies with different active gas compositions.Comment: 5 pages,12 figures, The 2nd International Conference on Particle Physics and Astrophysics (ICPPA-2016); Acknowledgments section correcte