Reduction of the Casimir force using aerogels

By using silicon oxide based aerogels we show numerically that the Casimir force can be reduced several orders of magnitude, making its effect negligible in nanodevices. This decrease in the Casimir force is also present even when the aerogels are deposited on metallic substrates. To calculate the Casimir force we model the dielectric function of silicon oxide aerogels using an effective medium dielectric function such as the Clausius-Mossotti approximation. The results show that both the porosity of the aerogel and its thickness can be use as control parameters to reduce the magnitude of the Casimir force.Comment: to appear J. Appl. Phy

Экономическая природа и классификация стейблкойнов

The article discusses the nature of stablecoins and their specifics in the financial market. The aim of the article is to reveal the economic nature and characteristics of various types of stablecoins. The author used system-functional and system-structural research methods as well as methods of statistical analysis and synthesis. The paper analyses different approaches to the interpretation of stablecoins and their regulation in developed countries, as well as provides the author’s interpretation and classification of stablecoins. The article analyses the main indicators of stablecoins and identifies the potential benefits and risks associated with payment. The conclusion is that stablecoins are to be interpreted as a new hybrid type of digital financial assets. Stablecoins are not homogeneous and may have different economic and legal characteristics. Clearly identified blockchain-based issuers issue most stablecoins as tradable digital bonds or depository receipts that can be used as a means of exchange, savings, and payment. The major economic and functional criteria for the classification of stablecoins are: the form of collateral, the category of users, and the scale of circulation. The research has shown that currently the most widely used are centralized stablecoins, backed by fiat currencies and gold, used for exchange transactions and retail payments. Local stablecoins are primarily a store of value and a medium of exchange. Their widespread use can significantly affect the development of the crypto-asset market by increasing its liquidity and stimulating the development of more stable forms of digital financial assets. Global stablecoins may gain widespread use as a cross-border means of payment. They can increase the speed of crossborder settlements and reduce their costs, as well as provide wider financial inclusion for users without bank accounts. To realize the potential benefits of stablecoins, one should address the legal, regulatory and supervisory challenges associated with national and cross-border circulation of stablecoins.Статья посвящена решению проблем интерпретации, классификации и функционирования стейблкойнов на финансовом рынке. Цель исследования — раскрытие экономической природы и выявление характерных особенностей различных видов стейблкойнов. Автор использовал следующие методы: системно-функциональный, системно-структурный, статистического анализа и синтеза. Проведен анализ различных подходов к интерпретации стейблкойнов и их регулированию в развитых странах; предложена авторская интерпретация и классификация стейблкойнов с учетом их экономических особенностей; проанализированы основные показатели использования стейблкойнов и определены потенциальные выгоды и риски их применения в платежных целях. Сделаны выводы, что стейблкойны следует интерпретировать в качестве новой гибридной разновидности цифровых финансовых активов. Они не являются однородными и могут обладать различными экономико-правовыми характеристиками. Большинство стейблкойнов выпускаются четко идентифицированными эмитентами на основе блокчейна в форме обращающихся цифровых обязательств или депозитарных расписок, которые могут использоваться в качестве средства обмена, сбережения и платежа. Основными экономико-функциональными критериями классификации стейбл-койнов являются: форма обеспечения, категория пользователей и масштаб обращения. Как показало исследование, в настоящее время наиболее широко используемыми являются централизованные стейблкойны, обеспеченные фи-атными валютами и золотом, применяемые для совершения биржевых обменных операций и розничных платежей. Локальные стейблкойны преимущественно используются в качестве средства сохранения стоимости и средства обмена. Их широкое применение может значительно повлиять на развитие рынка криптоактивов за счет повышения его ликвидности и стимулирования развития более стабильных форм цифровых финансовых активов. Глобальные стейблкойны могут получить широкое использование в качестве трансграничного средства платежа. Они способны повысить скорость трансграничных расчетов и снизить их себестоимость, а также обеспечить более широкий уровень финансовой доступности пользователям без банковских счетов. Тем не менее для реализации потенциальных преимуществ использования стейблкойнов необходимо решить правовые, нормативные и надзорные проблемы, связанные с национальным и трансграничным обращением стейблкойнов

Central Bank Digital Currencies: Experience of Introducing a Digital Yuan and Development of a Digital Ruble Conception

Objective: to determine the essential foundations of digital currencies of central banks and, based on the experience of the digital Yuan introduction in China, to substantiate the directions for improving the concept of the digital ruble introduction in Russia and the feasibility of issuing a digital currency in Belarus.Methods: the article uses empirical, logical, comparative and statistical methods within a systematic approach to determine the areas for improving the concept of development of a central banks digital currency.Results: the key characteristics of central banks digital currencies are determined; the features of models of retail digital currency systems are revealed; the main characteristics of the digital Yuan design and the features of its emission-settlement system organization are investigated; the main elements of the digital ruble concept of the Bank of Russia, the structure of its emission-settlement system and digital platform are examined; the issue of the feasibility of introducing the digital Belarusian ruble in the Republic of Belarus is investigated. We propose to develop additional mechanisms to protect the integrity and confidentiality of the payment information stored in the register of the Bank of Russia on the digital ruble platform, to differentiate the tools of digital wallets, and to set limits on individual payment transactions with the digital ruble.Scientific novelty: the study reveals the features of the model of a two-level system of retail digital currencies of central banks in China and Russia; the directions of improving the concept of the digital ruble introduction are determined and the expediency of issuing digital currency in the Republic of Belarus is justified.Practical significance: the main provisions and conclusions of the article can be used by economists, central banks and credit institutions in the development and improvement of the national digital currency design, its emission and settlement model and the development of the concept of its implementation, taking the world experience into account

Statistical Description of Hydrodynamic Processes in Ionic Melts with taking into account Polarization Effects

Statistical description of hydrodynamic processes for ionic melts is proposed with taking into account polarization effects caused by the deformation of external ionic shells. This description is carried out by means of the Zubarev nonequilibrium statistical operator method, appropriate for investigations of both strong and weak nonequilibrium processes. The nonequilibrium statistical operator and the generalized hydrodynamic equations that take into account polarization processes are received for ionic-polarization model of ionic molten salts when the nonequilibrium averaged values of densities of ions number, their momentum, dipole momentum and total energy are chosen for the reduced description parameters. A spectrum of collective excitations is investigated within the viscoelastic approximation for ion-polarization model of ionic melts.Comment: 24 pages, RevTex4.1-format, no figure

Центробанковские цифровые валюты: ключевые характеристики и направления влияния на денежно-кредитную и платежную системы

The article is devoted to the study of prospects for digital currency issue by central banks as a new form of central bank money and to the potential of their influence on monetary and credit system. The aim of the article is to interpret and classify central bank digital currencies, to identify key characteristics of digital currencies and possible models of their issue, as well as to define the main directions of influence of digital currencies on the monetary and credit and payment systems. The scientific novelty of the article is in the systematization and comparison of different ideas about the implementation of sovereign digital currencies considering the use of distributed registry technologies. The study analyzed the projects of central banks on the issue of digital currencies and identified their features. Possible directions of influence of central bank digital currencies on the monetary and credit policy of the Central Bank and the activities of credit institutions were determined. It revealed that central bank digital currencies can be considered as a new form of money of the Central Bank, which can be issued to be used both in retail and in wholesale payments. Digital currencies may differ in some characteristics. The key ones are: a way to integrate into the monetary and credit system; emission technology; currency storage method; mechanism of mutual settlements and anonymity level. The study showed that the main incentives for introducing digital currencies are the possibility to provide an alternative and universally accessible legal means of payment, as well as to provide faster, more transparent and cheaper in-country and cross-border payments. The influence of digital currencies on the monetary and credit system and the monetary and credit policy of the Central Bank will largely depend on the scenario of their system integration. If cash is simply replaced in circulation by digital currencies, the effect on the Central Bank monetary and credit system and policy will not be significant. However, if central bank digital currencies are issued as an addition to cash, or are in parallel circulation, they can strengthen the transmission mechanism of the monetary and credit policy and increase the centralization of assets on the Central Bank balance sheet, as well as reduce the funding provided by credit institutions.Статья посвящена исследованию перспектив выпуска центральными банками цифровых валют как новой формы центробанковских денег и потенциалу их влияния на денежно-кредитную систему. Цель статьи состоит в интерпретации цифровых валют и их классификации, выявлении ключевых характеристик цифровых валют и определении возможных моделей их выпуска, а также определении основных направлений влияния цифровых валют на денежно-кредитную и платежную системы. Научная новизна статьи выражается в систематизации и сопоставлении разных представлений о реализации суверенных цифровых валют с учетом использования технологий распределенных реестров. В рамках исследования проанализированы проекты центральных банков по эмиссии цифровых валют и выявлены их особенности. Определены возможные направления влияния центробанковских цифровых валют на денежно-кредитную политику ЦБ и деятельность кредитных институтов. Выявлено, что центробанковские цифровые валюты могут рассматриваться в качестве новой формы денег ЦБ, которая может выпускаться с целью использования как в розничных, так и в оптовых платежах. Цифровые валюты могут отличаться по ряду характеристик, ключевыми из которых являются: способ интеграции в денежно-кредитную систему; технология эмиссии; способ хранения валюты; механизм осуществления взаиморасчетов и степень анонимности. Как показало исследование, главные стимулы введения в обращение цифровых валют состоят в возможности предоставления альтернативного и универсально доступного законного средства платежа, а также обеспечении более быстрых, прозрачных и дешевых внутристрановых и трансграничных расчетов. Влияние цифровых валют на денежно-кредитную систему и денежно-кредитную политику ЦБ в значительной степени будет зависеть от сценария их системной интеграции. В случае простой замены наличных денег в обращении цифровыми валютами эффект на денежно-кредитную систему и политику ЦБ не будет значительным. Однако если центробанковские цифровые валюты будут выпускаться как дополнение к наличным деньгам или иметь параллельное с ними обращение, они способны усилить трансмиссионный механизм денежно-кредитной политики и повысить централизацию активов на балансе ЦБ, а также снизить объемы фондирования, предоставляемых кредитными институтами

Selfsimilarity and growth in Birkhoff sums for the golden rotation

We study Birkhoff sums S(k,a) = g(a)+g(2a)+...+g(ka) at the golden mean rotation number a with periodic continued fraction approximations p(n)/q(n), where g(x) = log(2-2 cos(2 pi x). The summation of such quantities with logarithmic singularity is motivated by critical KAM phenomena. We relate the boundedness of log- averaged Birkhoff sums S(k,a)/log(k) and the convergence of S(q(n),a) with the existence of an experimentally established limit function f(x) = lim S([x q(n)])(p(n+1)/q(n+1))-S([x q(n)])(p(n)/q(n)) for n to infinity on the interval [0,1]. The function f satisfies a functional equation f(ax) + (1-a) f(x)= b(x) with a monotone function b. The limit lim S(q(n),a) for n going to infinity can be expressed in terms of the function f.Comment: 14 pages, 8 figure

Enabling magnetic resonance imaging of hollow-core microstructured optical fibers via nanocomposite coating

Optical fibers are widely used in bioimaging systems as flexible endoscopes capable of low-invasive penetration inside hollow tissue cavities. Here, we report on the technique which allows magnetic resonance imaging (MRI) of hollow-core microstructured fibers (HC-MFs), paving the way for combing MRI and optical bioimaging. Our approach is based on Layer-by-Layer assembly of oppositely charged polyelectrolytes and magnetite nanoparticles on the inner core surface of HC-MFs. Incorporation of magnetite nanoparticles into polyelectrolyte layers renders HC-MFs visible for MRI and induces the red-shift in their transmission spectra. Specifically, the transmission shifts up to 60 nm have been revealed for the several-layers composite coating along with the high-quality contrast of HC-MFs in MRI scans. Our results shed light on marrying fiber-based endoscopy with MRI that opens novel possibilities for minimally invasive clinical diagnostics and surgical procedures in vivo.Comment: 11 pages, 6 figure

IN-HOSPITAL AND LONG TERM RESULTS OF PERCUTANEOUS CORONARY INTERVENTION WITH BIVENTRICULAR SUPPORT AND EXTRACORPOREAL MEMBRANE OXYGENATION

Patients, due to various reasons not indicated for coronary bypass (CABG), usually have extremely high risk of complications in percutaneous intervention (PCI) as well. Recently it was shown that extracorporeal membrane oxygenation (ECMO) might provide a necessary support in the case of high risk PCI. ECMO can be effective in PCI in patients with refractory cardiogenic shock too, however evidence base for the technological approach in high risk PCI remains underdeveloped.Aim. To evaluate in-hospital and long-term results of high risk PCI with biventricular bypass and ECMO in patients not fitted for CABG.Material and methods. We conducted a retrospective analysis of the treatment of 12 patients having extremely high risk of complications in CABG. In all cases PCI was done in conditions of biventricular bypass and ECMO. Stable angina and non-STelevation acute coronary syndrome occurred in 42 and 58% cases, respectively. Clinical picture of cardiogenic shock was the criteria of exclusion. All patients had severe comorbidity with high score by “EuroScore” — 6,3±4,9%. In all cases there was multivessel disease with high level of coronary lesion involvement by “Syntax Score” (30,1±10,1). Mean level of left ventricle ejection fraction was satisfactory — 51±12,6%. Ten patients (83%) had significant (≥50 %) lesion of unprotected stem of the left coronary artery (SLCA).Results. All procedures were successful. As a success of PCI we meant the opened artery with the flow rate not worse than TIMI 3 and absent of significant cardiovascular complications. Mean quantity of the implanted drug-eluting stents was 2,4±1. Full revascularization was reached in 42% cases. Residual value of “Syntax Score” was at the level about 6,33±6,88. Significant adverse cardiovascular complications (death, myocardial infarction, repeated non-planned revascularization) during inhospital phase were not registered. In one case there was an iliac artery dissection, that did not lead to necessity of surgery. Hemorrhagic complications were found just in one patients (8%, 2nd type by “BARC”). All patients were discharged. There were no any fatal cases or myocardial infarction (MI) in 6 months after observation. Two patients required another revascularization (17%). In long-term period there were no and signs of “definite” or “probable” stent thrombosis.Conclusion. PCI in the conditions of biventricular bypass and ECMO might be effective alternative strategy of revascularization in a cohort of patients not indicated for CABG due to high complications risk