Ferrimagnetism of the magnetoelectric compound Cu2_2OSeO3_3 probed by 77^{77}Se NMR

We present a thorough $^{77}$Se NMR study of a single crystal of the magnetoelectric compound Cu$_2$OSeO$_3$. The temperature dependence of the local electronic moments extracted from the NMR data is fully consistent with a magnetic phase transition from the high-T paramagnetic phase to a low-T ferrimagnetic state with 3/4 of the Cu$^{2+}$ ions aligned parallel and 1/4 aligned antiparallel to the applied field of 14.09 T. The transition to this 3up-1down magnetic state is not accompanied by any splitting of the NMR lines or any abrupt modification in their broadening, hence there is no observable reduction of the crystalline symmetry from its high-T cubic \textit{P}2$_1$3 space group. These results are in agreement with high resolution x-ray diffraction and magnetization data on powder samples reported previously by Bos {\it et al.} [Phys. Rev. B, {\bf 78}, 094416 (2008)]. We also develop a mean field theory description of the problem based on a microscopic spin Hamiltonian with one antiferromagnetic ($J_\text{afm}\simeq 68$ K) and one ferromagnetic ($J_\text{fm}\simeq -50$ K) nearest-neighbor exchange interaction

Singular solutions of the L^2-supercritical biharmonic Nonlinear Schrodinger equation

We use asymptotic analysis and numerical simulations to study peak-type singular solutions of the supercritical biharmonic NLS. These solutions have a quartic-root blowup rate, and collapse with a quasi self-similar universal profile, which is a zero-Hamiltonian solution of a fourth-order nonlinear eigenvalue problem

ВПЛИВ ВОЄННОГО СТАНУ НА ПЛАНУВАННЯ ЗОВНІШНЬОЕКОНОМІЧНОЇ ДІЯЛЬНОСТІ ПІДПРИЄМСТВА

The article is devoted to the peculiarities in the planning of foreign economic activity of enterprises that arose as a result of military aggression against Ukraine. The study reveals problems that complicate the process of planning foreign economic activity of enterprises in the country during the military aggression against it. There are two groups of such factors. The first group is general, which complicates the planning of all aspects of  entrepreneurial activity in times of war. These include increased risks of physical destruction, personnel, environmental, infrastructural, logistical and other problems that increase during this period. This affects the need to develop additional sections of the plan, as well as the use of planning tools to ensure its increased flexibility and manoeuvrability. The main indicators of foreign economic activity planning at the enterprise are: foreign exchange earnings divided into goods and product groups; the value of exports and the value of imports; profitability of export and import operations; range of export and import products; the share of exports in the value of products. The paper reveals special aspects of planning foreign economic activity, such as: the need to plan the so-called "portfolio" of foreign business partners, taking into account the principles of geographical, political and financial diversification; the need to take into account geopolitical, social, demographic, technological, environmental, religious and economic factors in other countries. In the new conditions, foreign economic planning should take into account the growing level of political risks, difficult choice of partners and establishing cooperation, temporary lack of control over part of the countries territory, partial (sometimes significant) loss of logistics  infrastructure, active protectionist policy that aimed at protecting national security interests, and others features.Статтю присвячено особливостям планування зовнішньоекономічної  діяльності підприємств, що виникли в результаті військової агресії РФ проти України. Розкриваються проблеми загального характеру, які впливають на процес планування діяльності підприємств в цілому. Особливої уваги приділено факторам, що ускладнюють планування саме  зовнішньоекономічної діяльності в умовах війни. В нових умовах таке планування повинно враховувати зростання рівня політичних ризиків, ускладнення вибору партнерів та налагодження співпраці, часткову втрату логістичної інфраструктури, активну протекціоністську політику держави, спрямовану на захист інтересів національної безпеки тощо

ФОРМУВАННЯ РИНКУ ЗЕМЛІ В УКРАЇНІ: ЗАБАГАНКА ЧИ НЕОБХІДНІСТЬ

The results of research on the problems of the land market in Ukraine are represented. The analysis of bills on the land market in Ukraine has been conducted and their positive and negative aspects have been identified. A number of practical recommendations for the development of the agricultural land market are proposed. However, we consider, that every villager or shareholder should have the right to sell his ‘real estate’, but only to the State Land Bank (which must be created), at market prices at European level. The bank provides through land auctions long-term lease of land to any investor (domestic, foreign) who will pay more with the obligatory requirement to maintain the quality characteristics of land and the development of processing capacity in the region of lease of agricultural land (united territorial communities). For the development of a Ukrainian village, the restriction of potential tenants in the area of 20 or 200 hectares of agricultural land is impossible. the The success of the farmer (the tenant, the investor) is possible only by means of free circulating capital which can be obtained through a closed cycle of production (agricultural products, livestock complexes, processing enterprises, sales, cash). For this purpose it is necessary to have agricultural lands with the area from 2000 hectares. The article also emphasizes the urgent need to bring normative monetary valuation of agricultural land to the average European level.Приведены результаты исследования проблем становления рынка земли в Украине. Проведен анализ законопроектов о рынке земель в Украине, выявлены их положительные и отрицательные стороны. Предложен ряд практических рекомендаций по развитию рынка земель сельскохозяйственного назначения. Отмечена необходимость приведения нормативной денежной оценки земель сельскохозяйственного назначения до среднеевропейского уровня и создание Государственного банка земли.Наведено результати дослідження проблем становлення ринку землі в Україні. Проведено аналіз законопроектів про ринок земель в Україні та виявлено їх позитивні і негативні сторони. Запропоновано ряд практичних рекомендацій щодо розвитку ринку земель сільськогосподарського призначення. Наголошено на необхідності приведення нормативної грошової оцінки земель сільськогосподарського призначення до середньоєвропейського рівня та створення Державного банку землі

ІНСТРУМЕНТАРІЙ МЕТОДОЛОГІЇ ОЩАДЛИВОГО ВИРОБНИЦТВА ЯК НЕВІД’ЄМНА СКЛАДОВА ОПТИМІЗАЦІЇ ДІЯЛЬНОСТІ ПІДПРИЄМСТВА

The article reveals the essence and importance of lean manufacturingconcept, identified its main components. To achieve the goals of leanproduction is impossible without compliance with its basic principles,application of methods and tools. On the basis of experience ofimplementation of lean production by Japanese and Western researchers it is systematized the tools of the methodology, highlighting the advantages, problems and limitations in the use of basic methods that can be successfully applied in the process of restructuring existing industries, and during the construction of new economical ventures. It is established that the tools of the methodology of lean production in practice allow to achieve a significant reduction in resource cost with constant quality of production in comparison with the traditional approach and significantly reduce the production cycle of converting raw materials into finished product and significantly reduce the time of marketing.Our analysis showed that the raw materials from which products aremade on traditional enterprises may be stored in warehouses for weeks or even months, while the process of their conversion, that is adding value, mostly measured in minutes or hours. Still, the production cycle of the products can last quite a long period from days to weeks or more,significantly affects the financial component of activity of the enterprise. The concept of lean production can significantly reduce the cycle time andminimize inventory and WIP, resulting in significantly increase theproductivity of the enterprise and its competitiveness.On the basis of the conducted researches it is established that thesystem of lean production, which the company focuses on long termdevelopment, will work effectively only if it will be a process of reorientation of the thinking of employees of narrow problems in understanding the whole production process and the vision of a common goal. Unlike other  management techniques, focused on strict regulation of the activities, the tools of the methodology of lean production allow to involve in the process optimization staff at all levels. Installed, in modern conditions for successful and competitive businesses the lean production philosophy should become a corporate culture and way of thinking of each employee.В статье раскрыта сущность и значение концепции бережливогопроизводства, определены ее основные компоненты. Доказано, чтоинструменты методологии бережливого производства на практикепозволяют достичь значительного снижения затрат ресурсов принеизменном качестве продукции по сравнению с традиционнымподходом и заметно сократить производственный цикл превращениясырья в готовый продукт и значительно сократить сроки сбытапродукции. Установлено, что система бережливого производства, которая ориентирует предприятие на долгосрочную перспективу развития, будет работать эффективно только в том случае, если произойдет процесс переориентации мышления работников с узкопрофильных задач на понимание всего производственного процесса и видение общей цели.У статті розкрито сутність та значення концепції ощадливого виробництва, визначено її основні компоненти. Досліджено, що інструменти методології ощадливого виробництва на практиці дають змогу досягти значного зниження витрат ресурсів при незмінній якості продукції порівняно з традиційним підходом та помітно скоротити виробничий цикл перетворення сировини в готовий продукт і значно зменшити терміни збуту продукції. Встановлено, що система ощадливого виробництва, яка орієнтує підприємство на довгострокову перспективу розвитку, працюватиме ефективно лише в тому випадку, якщо відбудеться процес переорієнтації мислення працівників з вузькопрофільних завдань на розуміння всього виробничого процесу та бачення загальної мети

Electrically-driven phase transition in magnetite nanostructures

Magnetite (Fe$_{3}$O$_{4}$), an archetypal transition metal oxide, has been used for thousands of years, from lodestones in primitive compasses[1] to a candidate material for magnetoelectronic devices.[2] In 1939 Verwey[3] found that bulk magnetite undergoes a transition at T$_{V}$ $\approx$ 120 K from a high temperature "bad metal" conducting phase to a low-temperature insulating phase. He suggested[4] that high temperature conduction is via the fluctuating and correlated valences of the octahedral iron atoms, and that the transition is the onset of charge ordering upon cooling. The Verwey transition mechanism and the question of charge ordering remain highly controversial.[5-11] Here we show that magnetite nanocrystals and single-crystal thin films exhibit an electrically driven phase transition below the Verwey temperature. The signature of this transition is the onset of sharp conductance switching in high electric fields, hysteretic in voltage. We demonstrate that this transition is not due to local heating, but instead is due to the breakdown of the correlated insulating state when driven out of equilibrium by electrical bias. We anticipate that further studies of this newly observed transition and its low-temperature conducting phase will shed light on how charge ordering and vibrational degrees of freedom determine the ground state of this important compound.Comment: 17 pages, 4 figure

Reflectance anisotropy spectroscopy of magnetite (110) surfaces

Reflectance anisotropy spectroscopy (RAS) has been used to measure the optical anisotropies of bulk and thin-film Fe3O4(110) surfaces. The spectra indicate that small shifts in energy of the optical transitions, associated with anisotropic strain or electric field gradients caused by the (110) surface termination or a native oxide layer, are responsible for the strong signal observed. The RAS response was then measured as a function of temperature. A distinct change in the RAS line-shape amplitude was observed in the spectral range from 0.8 to 1.6 eV for temperatures below the Verwey transition of the crystal. Finally, thin-film magnetite was grown by molecular beam epitaxy on MgO(110) substrates. Changes in the RAS spectra were found for different film thickness, suggesting that RAS can be used to monitor the growth of magnetite (110) films in situ. The thickness dependence of the RAS is discussed in terms of various models for the origin of the RAS signal

АКТИВНІ МЕТОДИ НАВЧАННЯ СТУДЕНТІВ-МЕДИКІВ

Current article represents the use of innovative activity in various components of educational process. It is described an active involvement of modern teaching methods based on self-work of students, interactive studying methodics and wide use of IT-technologies for distant studying. Usage of modern teaching methods is capable to improve the qualitative level of students’ knowledge and their interest in chosen profession. Presented complex of directions of innovative activities in addition to scientific and management performance compiles the basis of complex education development in medical university.У статті представлене застосування інноваційної діяльності в різних компонентах освітнього процесу: активне впровадження в навчальний процес нових методик навчання, oснованих на самостійній роботі студентів, інтерактивних методів навчання, широке використання IT-технологій для дистанційної освіти. Використання нових методик освіти підвищує якісний рівень знань студентів і зацікавленість в обраній професії. Дана сукупність складових напрямків інноваційної діяльності в поєднанні з науковою й управлінською діяльністю становить базу комплексного розвитку освіти в медичному університеті

A new view of electrochemistry at highly oriented pyrolytic graphite

Major new insights on electrochemical processes at graphite electrodes are reported, following extensive investigations of two of the most studied redox couples, Fe(CN)64–/3– and Ru(NH3)63+/2+. Experiments have been carried out on five different grades of highly oriented pyrolytic graphite (HOPG) that vary in step-edge height and surface coverage. Significantly, the same electrochemical characteristic is observed on all surfaces, independent of surface quality: initial cyclic voltammetry (CV) is close to reversible on freshly cleaved surfaces (>400 measurements for Fe(CN)64–/3– and >100 for Ru(NH3)63+/2+), in marked contrast to previous studies that have found very slow electron transfer (ET) kinetics, with an interpretation that ET only occurs at step edges. Significantly, high spatial resolution electrochemical imaging with scanning electrochemical cell microscopy, on the highest quality mechanically cleaved HOPG, demonstrates definitively that the pristine basal surface supports fast ET, and that ET is not confined to step edges. However, the history of the HOPG surface strongly influences the electrochemical behavior. Thus, Fe(CN)64–/3– shows markedly diminished ET kinetics with either extended exposure of the HOPG surface to the ambient environment or repeated CV measurements. In situ atomic force microscopy (AFM) reveals that the deterioration in apparent ET kinetics is coupled with the deposition of material on the HOPG electrode, while conducting-AFM highlights that, after cleaving, the local surface conductivity of HOPG deteriorates significantly with time. These observations and new insights are not only important for graphite, but have significant implications for electrochemistry at related carbon materials such as graphene and carbon nanotubes

Incorporating prior knowledge improves detection of differences in bacterial growth rate

BACKGROUND: Robust statistical detection of differences in the bacterial growth rate can be challenging, particularly when dealing with small differences or noisy data. The Bayesian approach provides a consistent framework for inferring model parameters and comparing hypotheses. The method captures the full uncertainty of parameter values, whilst making effective use of prior knowledge about a given system to improve estimation. RESULTS: We demonstrated the application of Bayesian analysis to bacterial growth curve comparison. Following extensive testing of the method, the analysis was applied to the large dataset of bacterial responses which are freely available at the web-resource, ComBase. Detection was found to be improved by using prior knowledge from clusters of previously analysed experimental results at similar environmental conditions. A comparison was also made to a more traditional statistical testing method, the F-test, and Bayesian analysis was found to perform more conclusively and to be capable of attributing significance to more subtle differences in growth rate. CONCLUSIONS: We have demonstrated that by making use of existing experimental knowledge, it is possible to significantly improve detection of differences in bacterial growth rate