Modeling of blood cell surface oscillations as fluid-filled multilayer viscoelastic shells

Rheological properties of the red blood cells (RBC) determine their movement in the larger and smaller blood vessels, oxygen and carbon dioxide delivery to/from the cells. Those properties vary significantly with age and health state of an organism. In this paper a new rheological model of RBC as a thin multilayer shell, which includes the cytoskeleton, lipid bilayer, glycocalyx, and hydrate shell as Maxwell's viscoelastic bodies is proposed. Mechanical properties of the rheological model in isotonic, isometric and dynamic experiments are studied. The oscillations of the surfaces of erythrocytes or other cells in the approximation of multilayer viscoelastic shell filled with a viscous fluid are investigated. The expressions for the dynamic Young’s modules and viscosity/fluidity coefficients as functions of the viscoelastic and geometric parameters of the layers are obtained. The problem of propagation of small perturbations along the cell surface is considered. The solutions of the problem in the form of Young and Lamé waves are obtained. The method of identification of the erythrocyte parameters from the experimental measurements of the wave propagation on the basis of the developed mathematical model for the purposes of clinical diagnostics of diseases with use of a microdrop of blood of the patient is proposed. Pages of the article in the issue: 40 - 43 Language of the article: Ukrainia

Running Genetic Algorithms in the Edge: A First Analysis

Nowadays, the volume of data produced by different kinds of devices is continuously growing, making even more difficult to solve the many optimization problems that impact directly on our living quality. For instance, Cisco projected that by 2019 the volume of data will reach 507.5 zettabytes per year, and the cloud traffic will quadruple. This is not sustainable in the long term, so it is a need to move part of the intelligence from the cloud to a highly decentralized computing model. Considering this, we propose a ubiquitous intelligent system which is composed by different kinds of endpoint devices such as smartphones, tablets, routers, wearables, and any other CPU powered device. We want to use this to solve tasks useful for smart cities. In this paper, we analyze if these devices are suitable for this purpose and how we have to adapt the optimization algorithms to be efficient using heterogeneous hardware. To do this, we perform a set of experiments in which we measure the speed, memory usage, and battery consumption of these devices for a set of binary and combinatorial problems. Our conclusions reveal the strong and weak features of each device to run future algorihms in the border of the cyber-physical system.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. This research has been partially funded by the Spanish MINECO and FEDER projects TIN2014-57341-R (http://moveon.lcc.uma.es), TIN2016-81766-REDT (http://cirti.es), TIN2017-88213-R (http://6city.lcc.uma.es), the Ministry of Education of Spain (FPU16/02595

ЗАСОБИ ПОЛІПШЕННЯ РОБОТИ ЗІ СТУДЕНТАМИ З АНГЛІЙСЬКОЮ МОВОЮ НАВЧАННЯ У МЕДИЧНИХ ВУЗАХ УКРАЇНИ В ЗАЛЕЖНОСТІ ВІД ВХІДНОГО РІВНЯ ЗНАНЬ ТА КРАЇНИ-ДОНОРА

The aim of the study – to find solutions of the main problems faced by teachers working with students of younger courses with English language learning. We have analyzed the main problems that could affect the effectiveness of the training of foreign students with English language learning.Materials and Methods. The study is based on the investigation of the materials obtained from public sources and on the personal experience of the authors. The article presents the modern technologies of testing of foreign students with English language studying, implemented at the Department of Medical and Biological Physics and Medical Informatics. We have proposed rating method of determination the residual after-school knowledge in mathematics, physics and level of English proficiency.Results and Discussion. At the Department of Medical and Biological Physics and Medical Informatics entered input rating test for foreign 1st year students with English language learning. After the testing the teacher will receive by e-mail the conclusion in the form of a table with the results of each student and the overall group result and provided recommendations on the composition and level of the group offered recommendations for holding classes with the features of specific educational groups. The work also examines the possible composition of academic groups and proposed some recommendations for improvement, taking into account all factors, such as the countries from which students had arrived.Conclusions. The proposed method allows the teachers to build a more successful educational process, which ultimately has a positive effect on the overall absorption rate. In the future we plan to extend testing of foreign students with Russian language of instruction, introducing entrance test in Russian language that can also help in improving the quality of medical education.Мета дослідження – знайти шляхи вирішення основних проблем, з якими стикаються викладачі, що працюють зі студентами-іноземцями молодших курсів з англійською мовою навчання. Проаналізувати основні проблеми, які можуть впливати на результативність навчання студентів-іноземців з англійською мовою навчання.Матеріали та методи дослідження. Дослідження базується на вивченні матеріалів, отриманих із відкритих джерел інформації та власного досвіду авторів. У статті наведені  сучасні технології тестування іноземних студентів з англійською мовою навчання, впроваджені на кафедрі медичної та біологічної фізики і медичної інформатики. Запропонований  рейтинговий спосіб визначення залишкових після школи знань з математики, фізики та рівень володіння англійською мовою.  Результати й обговорення. На кафедрі медичної та біологічної фізики і медичної інформатики впроваджене вхідне рейтингове тестування іноземних студентів 1 курсу з англійською мовою навчання. Після проведення тестування викладачеві на електронну пошту надсилаються висновки у вигляді таблиці з результатами кожного студента та загальним результатом групи і надаються рекомендації щодо складу та рівня групи, пропонуються рекомендації з  проведення занять з урахуванням особливостей конкретних навчальних груп. Також у роботі проаналізований можливий склад академічних груп та запропоновані деякі рекомендації щодо поліпшення роботи з урахуванням усіх факторів, наприклад, з урахуванням країн, з яких прибули студенти.Висновки. Запропонований метод дозволяє викладачеві успішніше будувати освітній процес, що, в кінцевому підсумку, позитивно позначається на загальному засвоєнні курсу. У подальшому планується поширити тестування на студентів-іноземців із російською мовою навчання, запровадивши вхідне тестування російською мовою, що також може допомогти у вдосконаленні якості медичної освіти

XFEL structures of the human MT2 melatonin receptor reveal the basis of subtype selectivity

The human MT1 and MT2 melatonin receptors1,2 are G-protein-coupled receptors (GPCRs) that help to regulate circadian rhythm and sleep patterns3. Drug development efforts have targeted both receptors for the treatment of insomnia, circadian rhythm and mood disorders, and cancer3, and MT2 has also been implicated in type 2 diabetes4,5. Here we report X-ray free electron laser (XFEL) structures of the human MT2 receptor in complex with the agonists 2-phenylmelatonin (2-PMT) and ramelteon6 at resolutions of 2.8 Å and 3.3 Å, respectively, along with two structures of function-related mutants: H2085.46A (superscripts represent the Ballesteros–Weinstein residue numbering nomenclature7) and N862.50D, obtained in complex with 2-PMT. Comparison of the structures of MT2 with a published structure8 of MT1 reveals that, despite conservation of the orthosteric ligand-binding site residues, there are notable conformational variations as well as differences in [3H]melatonin dissociation kinetics that provide insights into the selectivity between melatonin receptor subtypes. A membrane-buried lateral ligand entry channel is observed in both MT1 and MT2, but in addition the MT2 structures reveal a narrow opening towards the solvent in the extracellular part of the receptor. We provide functional and kinetic data that support a prominent role for intramembrane ligand entry in both receptors, and suggest that there might also be an extracellular entry path in MT2. Our findings contribute to a molecular understanding of melatonin receptor subtype selectivity and ligand access modes, which are essential for the design of highly selective melatonin tool compounds and therapeutic agents. © 2019, The Author(s), under exclusive licence to Springer Nature Limited

Publisher Correction: Structural basis of ligand recognition at the human MT1 melatonin receptor (Nature, (2019), 569, 7755, (284-288), 10.1038/s41586-019-1141-3)

Change history: In this Letter, the rotation signs around 90°, 135° and 15° were missing and in the HTML, Extended Data Tables 2 and 3 were the wrong tables; these errors have been corrected online. © 2019, The Author(s), under exclusive licence to Springer Nature Limited

Structural basis of ligand recognition at the human MT1 melatonin receptor

Melatonin (N-acetyl-5-methoxytryptamine) is a neurohormone that maintains circadian rhythms1 by synchronization to environmental cues and is involved in diverse physiological processes2 such as the regulation of blood pressure and core body temperature, oncogenesis, and immune function3. Melatonin is formed in the pineal gland in a light-regulated manner4 by enzymatic conversion from 5-hydroxytryptamine (5-HT or serotonin), and modulates sleep and wakefulness5 by activating two high-affinity G-protein-coupled receptors, type 1A (MT1) and type 1B (MT2)3,6. Shift work, travel, and ubiquitous artificial lighting can disrupt natural circadian rhythms; as a result, sleep disorders affect a substantial population in modern society and pose a considerable economic burden7. Over-the-counter melatonin is widely used to alleviate jet lag and as a safer alternative to benzodiazepines and other sleeping aids8,9, and is one of the most popular supplements in the United States10. Here, we present high-resolution room-temperature X-ray free electron laser (XFEL) structures of MT1 in complex with four agonists: the insomnia drug ramelteon11, two melatonin analogues, and the mixed melatonin–serotonin antidepressant agomelatine12,13. The structure of MT2 is described in an accompanying paper14. Although the MT1 and 5-HT receptors have similar endogenous ligands, and agomelatine acts on both receptors, the receptors differ markedly in the structure and composition of their ligand pockets; in MT1, access to the ligand pocket is tightly sealed from solvent by extracellular loop 2, leaving only a narrow channel between transmembrane helices IV and V that connects it to the lipid bilayer. The binding site is extremely compact, and ligands interact with MT1 mainly by strong aromatic stacking with Phe179 and auxiliary hydrogen bonds with Asn162 and Gln181. Our structures provide an unexpected example of atypical ligand entry for a non-lipid receptor, lay the molecular foundation of ligand recognition by melatonin receptors, and will facilitate the design of future tool compounds and therapeutic agents, while their comparison to 5-HT receptors yields insights into the evolution and polypharmacology of G-protein-coupled receptors

Maghetohydrodynamic flows of micro/nano fluids through thin capillaries

Steady magnetohydrodynamic (MHD) flows of suspensions of conducting micro/nanoparticles through a thin tube of a circular cross-section in a transverse constant magnetic field driven by a constant pressure drops at the ends of the tube is studied. The governing MHD system of equations for a viscous incompressible micro/nanofluid in the non-induction approximation is solved with the second order velocity slip boundary condition at the wall of the tube. The material parameters of the fluid are considered as nonlinear functions of the particle concentration according to the mixture models of suspensions and electric conductivity theory. The velocity field, pressure, electric current and magnetic field have been computed as series expansions. The influence of two non-dimensional slip coefficients of the flow rate and wall shear stress is studied. Optimal concentrations of the micro/nanoparticles in the suspensions have been computed from the minimum entropy production condition for different slip conditions, material parameters, magnetic fields and flow regimes (Reynolds and Hartmann numbers).Key words: Microfluids, Nanofluids, Magnetohydrodynamics, Steady flows.Pages of the article in the issue: 32 - 36Language of the article: EnglishSteady magnetohydrodynamic (MHD) flows of suspensions of conducting micro/nanoparticles through a thin tube of a circular cross-section in a transverse constant magnetic field driven by a constant pressure drops at the ends of the tube is studied. The governing MHD system of equations for a viscous incompressible micro/nanofluid in the non-induction approximation is solved with the second order velocity slip boundary condition at the wall of the tube. The material parameters of the fluid are considered as nonlinear functions of the particle concentration according to the mixture models of suspensions and electric conductivity theory. The velocity field, pressure, electric current and magnetic field have been computed as series expansions. The influence of two non-dimensional slip coefficients of the flow rate and wall shear stress is studied. Optimal concentrations of the micro/nanoparticles in the suspensions have been computed from the minimum entropy production condition for different slip conditions, material parameters, magnetic fields and flow regimes (Reynolds and Hartmann numbers).Key words: Microfluids, Nanofluids, Magnetohydrodynamics, Steady flows.Pages of the article in the issue: 32 - 36Language of the article: Englis

Methods of Determination of Initial Level of Students' Knowledges on Basic Disciplines at Higher Medical Educational Institutions

Authors propose the program, which determines the input level of knowledge of students in Ukraine medical schools with English as the language of studying. It assesses the level of residual knowledge in mathematics, physics and English and also gives recommendations for teaching in the group, taking into account the characteristics of specific educational group. The program allows the teacher to build a more successful educational process, which in the end, improves the overall result. For testing the students and teacher should be provided with personal computers with operational system Windows 98 and higher or Linux OS with graphical interface and support the Wine program. The questions (in English) pre-installed in the testing program and correspond to the program in physics of high school and to basic mathematical course. English questions do not include grammar checking, but created to check the meaning of written text and basic vocabulary. A significant advantage of the program is the ability to add and reduce the number of questions in the test, in case of, for example, lack of time, and teachers can change the questions themselves. The beginning and the end of the test set by the teacher. The program allows the teacher to build a more successful educational process, which improves the overall resul