Clinotron: a Promising Source for THz Regions

Potentials of the backward-wave oscillator (BWO) with an inclined electron beam (the clinotron) as a source of electromagnetic radiation in THz regions are examined. A self-consistent collective electron-wave interaction theory is developed to study starting conditions and steady state oscillations of clinotron tubes. Optimization of the geometry of pulsed and continuous wave (CW) 1-THz clinotrons is carried out and a possibility of the development of promising tubes for this frequency region is found.Рассмотрены перспективы использования лампы обратной волны с наклонённым электронным пучком (клинотрона) как источника электромагнитного излучения терагерцевого диапазона частот. Для изучения пусковых условий и стационарных колебаний клинотрона разработана самосогласованная теория коллективного взаимодействия электронов с волной. Обнаружена возможность разработки перспективных ламп для терагерцевого диапазона частот и проведена оптимизация геометрии клинотронов импульсного и непрерывного действия с частотой генерации 1 ТГц.Розглянуто перспективи використання лампи зворотної хвилі з нахиленим електронним пучком (клінотрона) як джерела електромагнітного випромінювання терагерцевого діапазону частот. Для вивчення пускових умов та стаціонарних коливань клінотрона розроблено самоузгоджену теорію колективної взаємодії електронів з хвилею. Виявлено можливість розробки перспективних ламп для терагерцевого діапазону частот и проведено оптимізацію геометрії клінотронів імпульсної та безперервної дії з частотою генерації 1 ТГц

Results of therapy of chronic urticaria in patients with IgE-dependent and IgE-independent disease profile

The main mechanism for the occurrence of urticaria is the degranulation of mast cells. It has been proven that, regardless of the activation pathway, clinical manifestations will not differ. According to the literature, up to half of cases of chronic spontaneous urticaria are autoimmune in nature, can be combined with autoimmune thyroid disease, SLE, etc., and have a more severe course.In therapy, antihistamines are traditionally used. However, some patients do not respond to the treatment, even with a multiple increase in doses. In the treatment of urticaria resistant to traditional antihistamines, the use of Omalizumab is recommended. The purpose of the study: to determine the profile of patients with chronic urticaria, as well as to evaluate the effectiveness of treatment with Omalizumab in patients with IgE- dependent and IgE-independent chronic urticaria.Eight-one patients with chronic urticaria (60 adults, 21 children) were examined. Patients before the start of therapy had a long history of CU: from 1 to 20 years. Patients before the start of therapy were treated with antihistamines, but no control was obtained. An increase in the level of serum IgE was detected in 51.7% of cases in adults and 42% in children. Concomitant sensitization was determined in 48.3% of adults and 76.2% of children. In children, food, epidermal and pollen sensitization was the most common. Pollen and epidermal sensitization were more common in adults. The level of eosinophilia in the group with IgE-dependent was more pronounced than in other group (p = 0.0097). After 6 months, the group with IgE-dependent showed an improvement in the symptom score (UCT) from 3.1 CI (1.5-4.6) to 12.2 CI (10.8-13.7), (p = 0.0001). In other group, symptoms improved from 0.63 CI (0.36-1.6) to 8.1 CI (5-11.2) after 6 months (no control). After 6 months of genetically engineered biological therapy (GIBT), complete control over the symptoms of CU in group 1 was obtained in 66.7% of patients, partial — in 33.7%. In the second group, in 33.3% of cases, positive treatment results could not be achieved. Thus, genetically engineered biological therapy with Omalizumab increases the control over the course of CU. Treatment outcomes are higher in patients with an IgE-dependent disease profile

Biological diversity of the coastal zone of the Crimean peninsula: problems, preservation and restoration pathways

The results of complex hydrochemical, hydrobiological and ichthyological investigations by IBSS, NAS of Ukraine, realized in 6 regions of the coastal zone of the Crimean peninsula in the Black Sea and the Sea of Azov are given. The main negative factors causing changes in structural and functional characteristics of hydrobiocenoses in the regions studied are analyzed and “hot ecological spots” are isolated. Variants of different methods of management of the coastal ecosystems, including construction of artificial reefs and usage of biological filters for water cleaning, protection and recreation of biological diversity are taken into consideration

Building nonparametric nn-body force fields using Gaussian process regression

Constructing a classical potential suited to simulate a given atomic system is a remarkably difficult task. This chapter presents a framework under which this problem can be tackled, based on the Bayesian construction of nonparametric force fields of a given order using Gaussian process (GP) priors. The formalism of GP regression is first reviewed, particularly in relation to its application in learning local atomic energies and forces. For accurate regression it is fundamental to incorporate prior knowledge into the GP kernel function. To this end, this chapter details how properties of smoothness, invariance and interaction order of a force field can be encoded into corresponding kernel properties. A range of kernels is then proposed, possessing all the required properties and an adjustable parameter $n$ governing the interaction order modelled. The order $n$ best suited to describe a given system can be found automatically within the Bayesian framework by maximisation of the marginal likelihood. The procedure is first tested on a toy model of known interaction and later applied to two real materials described at the DFT level of accuracy. The models automatically selected for the two materials were found to be in agreement with physical intuition. More in general, it was found that lower order (simpler) models should be chosen when the data are not sufficient to resolve more complex interactions. Low $n$ GPs can be further sped up by orders of magnitude by constructing the corresponding tabulated force field, here named "MFF".Comment: 31 pages, 11 figures, book chapte

Roadmap on Machine learning in electronic structure

AbstractIn recent years, we have been witnessing a paradigm shift in computational materials science. In fact, traditional methods, mostly developed in the second half of the XXth century, are being complemented, extended, and sometimes even completely replaced by faster, simpler, and often more accurate approaches. The new approaches, that we collectively label by machine learning, have their origins in the fields of informatics and artificial intelligence, but are making rapid inroads in all other branches of science. With this in mind, this Roadmap article, consisting of multiple contributions from experts across the field, discusses the use of machine learning in materials science, and share perspectives on current and future challenges in problems as diverse as the prediction of materials properties, the construction of force-fields, the development of exchange correlation functionals for density-functional theory, the solution of the many-body problem, and more. In spite of the already numerous and exciting success stories, we are just at the beginning of a long path that will reshape materials science for the many challenges of the XXIth century

Roadmap on Machine learning in electronic structure

In recent years, we have been witnessing a paradigm shift in computational materials science. In fact, traditional methods, mostly developed in the second half of the XXth century, are being complemented, extended, and sometimes even completely replaced by faster, simpler, and often more accurate approaches. The new approaches, that we collectively label by machine learning, have their origins in the fields of informatics and artificial intelligence, but are making rapid inroads in all other branches of science. With this in mind, this Roadmap article, consisting of multiple contributions from experts across the field, discusses the use of machine learning in materials science, and share perspectives on current and future challenges in problems as diverse as the prediction of materials properties, the construction of force-fields, the development of exchange correlation functionals for density-functional theory, the solution of the many-body problem, and more. In spite of the already numerous and exciting success stories, we are just at the beginning of a long path that will reshape materials science for the many challenges of the XXIth century.</p

The situation of bank lending in Ukraine: current problems and prospects of recovery

The article investigates the state of bank lending in Ukraine, identifies the source of the severe banking crisis, that broke out in Ukraine in 2014-2015. Additionally, it suggests recommendations for the enhancement of the role of bank lending in the process of expanded incentives for investments in order to facilitate the exit from the economy crisis towards the economic growth. Using the general scientific methods of empirical and theoretical research, the dynamics of bank lending in Ukraine in 2003- 2014 was analysed and the following periods were distinguished: 2003-2007, which is the period of the rise of a strong banking system and the increase of bank lending; 2008-2009, when the crisis and post-crisis recovery processes have been attempted, and 2014-2015, which is the period of an unprecedented crisis and a wave of bank failures. The analysis revealed the following main factors constraining the lending to the economy of Ukraine in today's conditions: a slowdown in the economic growth, increasing economic and political risks of inflation and devaluation expectations, rapid fluctuations of exchange rate, a high cost and the lack of credit because of insufficient domestic resources and the mismatch of terms and conditions of bank loans with the aim to attract resources, a significant credit risk and imperfect methods of management, the lack of clear mechanisms for loan repayment applicable to insolvent borrowers, and inadequate protection of the rights of lenders and borrowers. The article substantiates that the stimulation of the lending process should be based on the following: the improvement of the investment climate in Ukraine, using stricter lending criteria, ensuring effective mechanisms for provisioning for credit risks, and the improvement of measures for the protection of rights of lenders and borrowers. The state should focus on new projects stimulating – international investments by introducing the European standards on domestic enterprises, including joint investment projects in strategic sectors; the promotion of investment projects in support of small and medium enterprises; and intensified efforts to stimulate foreign banks to open credit lines for small and medium-sized businesses to implement energy efficiency projects under the state guarantee

Lithium and sodium storage on tetracyanoethylene (TCNE) and TCNE-(doped)-graphene complexes: A computational study

10.1016/j.matchemphys.2015.02.045Materials Chemistry and Physics156180-18

Understanding doping strategies in the design of organic electrode materials for Li and Na ion batteries: An electronic structure perspective

10.1039/c7cp01554bPhysical Chemistry Chemical Physics192013195-1320