Relaxation of superflow in a network: an application to the dislocation model of supersolidity of helium crystals

We have considered the dislocation network model for the supersolid state in He-4 crystals. In difference with uniform 2D and 3D systems, the temperature of superfluid transition T_c in the network is much smaller than the degeneracy temperature T_d. It is shown that a crossover into a quasi superfluid state occurs in the temperature interval between T_c and T_d. Below the crossover temperature the time of decay of the flow increases exponentially under decrease of the temperature. The crossover has a continuous character and the crossover temperature does not depend on the density of dislocations.Comment: Corrected typo

Non-dissipative drag of superflow in a two-component Bose gas

A microscopic theory of a non-dissipative drag in a two-component superfluid Bose gas is developed. The expression for the drag current in the system with the components of different atomic masses, densities and scattering lengths is derived. It is shown that the drag current is proportional to the square root of the gas parameter. The temperature dependence of the drag current is studied and it is shown that at temperature of order or smaller than the interaction energy the temperature reduction of the drag current is rather small. A possible way of measuring the drag factor is proposed. A toroidal system with the drag component confined in two half-ring wells separated by two Josephson barriers is considered. Under certain condition such a system can be treated as a Bose-Einstein counterpart of the Josephson charge qubit in an external magnetic field. It is shown that the measurement of the difference of number of atoms in two wells under a controlled evolution of the state of the qubit allows to determine the drag factor.Comment: 13 pages, 3 figures. This preprint is extended and substantially revised variant of related preprint cond-mat/040456

ДОЦІЛЬНІСТЬ ТА РИЗИКИ ІНВЕСТУВАННЯ В СУЧАСНІ ФІНАНСОВІ ІНСТРУМЕНТИ

Relevance of the article is that the post–crisis economic recovery and the rapid development of European integration are both – a cause and a consequence of higher investment activity, which causes the expansion of the frontiers of the use of financial instruments while increasing the their riskiness in the current economic conditions. The dynamics of sales of financial instruments used in the investment process in the financial market of Ukraine, such as stocks, corporate bonds, government bonds of Ukraine, local bonds, savings certificates, certificates of deposit of the National Bank of Ukraine, investment certificates, mortgage bonds, option certificates, derivatives. The types of risks inherent to all modern financial instruments and specifies types of risks that are specific to certain types of financial instruments are shown.The advantage of investing in certain types of financial instruments is grounded. The directions of risk reduce in exposure of investment in modern financial instruments, such as diversification (by type of instrument, the currency of a financial instrument, the countries issue a financial instrument, capitalization and sector of the issuer of financial instruments) and investment taking into account the time interval investment are offered. The main idea of the article was to prove the rationale for investing assets in financial instruments with simultaneous identification of risks that accompany this process, for finding out the ways to minimize them in the future.Актуальность статьи заключается в том, что посткризисное восстановление экономики страны и стремительное развитие евроинтеграционного процесса являются одновременно и причиной, и следствием повышения уровня инвестиционной активности, которое вызывает расширение границ использования финансовых инструментов при одновременном увеличении их рискованности в современных экономических условиях. Проанализирована динамика объемов реализации финансовых инструментов, используемых в инвестиционном процессе на финансовом рынке Украины. Определены виды рисков, присущие всем современным финансовым инструментам, и такие, которые являются специфическими для отдельных их видов. Главной идеей статьи стало обоснование целесообразности инвестирования активов в финансовые инструменты с одновременной идентификацией рисков, сопровождающих этот процесс, для поиска путей их минимизации в перспективе.Актуальність статті полягає у тому, що посткризове відновлення економіки країни та стрімкий розвиток євроінтеграційного процесу є одночасно і причиною, і наслідком підвищення рівня інвестиційної активності, яке зумовлює розширення меж використання фінансових інструментів при одночасному збільшенні їх ризиковості у сучасних економічних умовах. Проаналізовано динаміку обсягів реалізації фінансових інструментів, що використовуються у інвестиційному процесі, на фінансовому ринку України. Визначено види ризиків, притаманних для усіх сучасних фінансових інструментів, та таких, що є специфічними для окремих їх видів. Головною ідеєю статті стало обґрунтування доцільності інвестування активів у фінансові інструменти з одночасною ідентифікацією ризиків, що супроводжують цей процес, задля пошуку шляхів їх мінімізації у перспективі

Competing ideologies of Russia's civil society

Many analysts and public opinion makers in the West conflate the notions of Russia’s non-systemic liberal opposition and the country’s civil society. Indeed, despite garnering the support of a minority of Russia’s population, non-systemic liberal opposition represents a well-organized civic group with a clearly articulated agenda and the ability to take action. Yet, does Russia’s civil society end there? A closer look at the country’s politics shows that Russia has a substantial conservative-traditionalist faction that has also developed agenda for action and formulated opinions. This group is anti-liberal rather than illiberal ideologically and pro-strong state/pro a geopolitically independent Russia rather than pro-Kremlin politically. The interaction between liberal and conservative civic groups represents the battle of meanings, ideas, and ethics, and ultimately determines the future trajectory of Russia’s evolution. Thus, the analysis of Russia’s civil society must represent a rather more nuanced picture than a mere study of the liberal non-systemic opposition. This article will examine the complexity of Russia’s civil society scene with reference to the interplay between the liberal opposition and conservative majority factions. The paper will argue that such complexity stems from ideological value pluralism that falls far beyond the boundaries of the liberal consensus, often skewing our understanding of political practice in Russia

Drag of superfluid current in bilayer Bose systems

An effect of nondissipative drag of a superfluid flow in a system of two Bose gases confined in two parallel quasi two-dimensional traps is studied. Using an approach based on introduction of density and phase operators we compute the drag current at zero and finite temperatures for arbitrary ratio of densities of the particles in the adjacent layers. We demonstrate that in a system of two ring-shape traps the "drag force" influences on the drag trap in the same way as an external magnetic flux influences on a superconducting ring. It allows to use the drag effect to control persistent current states in superfluids and opens a possibility for implementing a Bose analog of the superconducting Josephson flux qubit.Comment: 12 pages, 2 figures, new section is added, refs are adde

Trapping atoms on a transparent permanent-magnet atom chip

We describe experiments on trapping of atoms in microscopic magneto-optical traps on an optically transparent permanent-magnet atom chip. The chip is made of magnetically hard ferrite-garnet material deposited on a dielectric substrate. The confining magnetic fields are produced by miniature magnetized patterns recorded in the film by magneto-optical techniques. We trap Rb atoms on these structures by applying three crossed pairs of counter-propagating laser beams in the conventional magneto-optical trapping (MOT) geometry. We demonstrate the flexibility of the concept in creation and in-situ modification of the trapping geometries through several experiments.Comment: Modifications: A) Reference I. Barb et al., Eur. Phys. JD, 35, 75 (2005) added. B)Sentence rewritten: We routinely capture more than 10^6 atoms in a micro-MOT on a magnetized pattern. C) The magnetic field strengths are now given in Teslas. D) The second sentence in the fourth paragraph has been rewritten in order to more clearly describe the geometry and purpose of the compensation coils.E) In the seventh paragraph we have rewritten the sentence about the creation of the external magnetic field for the magnetic-domain patterning. F) In the ninth paragraph, we clarify the way to shift the trap center. G) Caption of Fig. 4 changed. H) We have modified paragraph 12 to improve the description on the guiding of the trap center along a toroidal pattern. I) The last two sentences of the manuscript have been rewritte