Focusing of laser-generated ion beams by a plasma cylinder: similarity theory and the thick lens formula

It is shown that plasma-based optics can be used to guide and focus highly divergent laser-generated ion beams. A hollow cylinder is considered, which initially contains a hot electron population. Plasma streaming toward the cylinder axis maintains a focusing electrostatic field due to the positive radial pressure gradient. The cylinder works as thick lens, whose parameters are obtained from similarity theory for freely expanding plasma in cylindrical geometry. Because the lens parameters are energy dependent, the lens focuses a selected energy range of ions and works as a monochromator. Because the focusing is due to the quasineutral part of the expanding plasma, the lens parameters depend on the hot electron temperature $T_e$ only, and not their density

Application of the transferred matrix method to a unified evaluation of the cathodic electron emission

The work is concerned with the Transfer Matrix Method for solving the steady-state Schrödinger equation applied for a unified evaluation of the emission current density from non-refractory cathodes. The method is applicable to arbitrary shapes of the potential barrier and its transmission probability is obtained without any analytical approximations. The Fermi-Dirac distribution for the free electrons in the metal is considered as a supply function. The results, obtained for a work function of the cathode material of 4.5 eV over a wide range of values of the surface temperature and the electric field strength, clearly show a growing deviation from those obtained by the classical Jeffreys-Wentzel-Kramers-Brillouin approximation with the increase of the electric field strength. Preliminary results are obtained to demonstrate the applicability of the Transfer Matrix method to the evaluation of the ion-assisted electron emission. A significant local enhancement of the emission current density is obtained as a result of the presence of an ion at a fixed position near the metal surface. The effect becomes very strongly pronounced at an appropriate value of the electric field strength, for which a resonant ion contribution appears

The day before the crash – Bulgarian‑Soviet relations in the nineteen eighties

This article is devoted to changes in Bulgarian-Soviet relations in the last decade of the twentieth century. Throughout the whole postwar period the relations between Bulgaria and the Soviet Union were exceptionally close. The connections were rather one-way - the USSR gave Bulgaria economic aid and thanks to that the country became more industrialized and almost until the end of the system could count on Soviet loans and raw materials. Bulgaria in turn repaid the political obedience and the demonstration of particularly close relations binding itself with the USSR, which gave foreign and domestic analysts the bases to name Bulgaria „the most loyal Soviet satellite.” However, along with the end of the Cold War there has been a fundamental geopolitical change. „Special” relations between Bulgaria and the Soviet Union, of which Bulgaria was proud and which were used, were transformed into a barrier and a cause of problems in the Bulgarian transition to market economy. The path, which Bulgaria had to undergo, proved to be longer than in the case of other the Eastern Bloc countries preserving a greater distance of the Soviet Union. Even before the overthrow of Zhivkov, a new trend could be seen - the reorientation of Bulgarian foreign policy from East to West. During the autumn session of the General Assembly of the UN in New York, Petar Mladenov spoke with US Secretary of State, James Baker, and almost openly promised him an immediate implementation of changes in Bulgaria. This indicates that the political forces after Zhivkov in Bulgarian Communist Party were prepared not only to follow Gorbachev, but also to reorient foreign policy of Bulgaria - something that was made by other politicians in the last decade of the twentieth century

The role of the international loan in the development of world economy

Розглянуто напрями та основні цілі функціонування міжнародних кредитів. Вказано випадки, за яких виникають міжнародні кредитні відносини. Зазначено порядок та умови надання міжнародного кредиту. Названі суб’єкти та об’єкти кредитних відносин. Розглянуто види та форми міжнародного кредиту. Досліджено принципи та функції міжнародного кредитування. Запропоновано доповнити існуючу класифікацію загальноприйнятих функцій. Проаналізовано роль та вплив міжнародного кредиту на розвиток міжнародних економічних відносин.The article shows the directions and main goals of the operation of international loans. The cases where international credit relations occur are revealed. The procedure and terms of providing the international credit are indicated. The subjects and objects of credit relations are stated. Types and forms of international credit are regarded. The principles and functions of international credit are studied. It is offered to complement the existing classification of generally excepted functions. The role and impact of international credit on the development of international economic relations are analyzed

Main problems at integrating educational interactive multimedia in the foreign language teaching on a phonological level of language acquisition

Цель данного исследования является представление основные проблемы при разработке интегрированной компьютерной среде, которая поможет в процессе обучения иностранному языку на фонологическом уровне. Она позволяет модернизировать систему образования на основе использования информационных и комуникационных технологий, которые сегодня предлагают новые перспективы и возможности для обучения. В проекте рассматриваются педагогические аспекты применения учебных мультимедиа. Он имеет дело с осознанием эффективности и критическим использованием образовятельных мультимедия, а также педагогическими и этическими аспектами их применения.The aim of this paper is to present the main challenges in developing an integrated computer environment that will help foreigners in the process of language learning on constructing its phonological level.It allows mo upgrade the education system through the use of information and communication technologies, which today offer new perspectives and opportunities for learning. The project considers educational aspects of the use of educational multimedia. It deals with the realization of efficiency and the use of critical educational multimedia, as well as pedagogical and ethical aspects of their application

Energising Bulgaria

Bulgaria’s newly elected conservative President Rosen Plevneliev will take the reins at the end of January 2012. Bulgaria being a parliamentary republic with the head of state charged with largely ceremonial and representative functions, you might ask what did the election outcome in October 2011 signal to Europe? The recently held elections showed that the incumbent ruling party Citizen’s for the European Development of Bulgaria (GERB) solidified its hold over both presidential and municipal levels, despite evident wanning party support. The new president pledges to boost economic growth and employment and improve the business environment. He vows to step up judicial reforms and tackle corruption to better Bulgaria’s image, essentially sounding somewhat like a prime ministerial speech

Yoctosecond photon pulses from quark-gluon plasmas

Present ultra-fast laser optics is at the frontier between atto- and zeptosecond photon pulses, giving rise to unprecedented applications. We show that high-energetic photon pulses down to the yoctosecond timescale can be produced in heavy ion collisions. We focus on photons produced during the initial phase of the expanding quark-gluon plasma. We study how the time evolution and properties of the plasma may influence the duration and shape of the photon pulse. Prospects for achieving double peak structures suitable for pump-probe experiments at the yoctosecond timescale are discussed.Comment: 4 pages, 2 figures; final version as accepted by PR

Metareference as a Public Service : Performed by Contemporary Narrative Media

Building on decades' worth of research by scholars such as L. Hutcheon, W. Nöth, A. Nünning, I. O. Rajewsky, P. Waugh, W. Wolf and others on the topics of self-reference, metafiction and metanarration, this transmedial study aims to demonstrate that far from being "narcissistic narrative[s]" (Hutcheon), many contemporary metareferential works attempt to perform a public service, namely that of educating the general public. For the purpose of this demonstration, the present doctoral thesis first provides a critical analysis of both the early and the current terminology used in the study of metareference, as well as an in-depth discussion of the functions and effects traditionally ascribed to the use of metareference, both in fiction in general and in specific media. Building on this theoretical foundation, this dissertation subsequently proceeds to examine eleven contemporary works from five different narrative media, all of which utilise numerous different types of metareferences to achieve their ultimately didactic goal of raising their audience's medium-awareness, specifically in regards to the role the respective medium plays in society. Within the medium of literature, this study analyses I. McEwan's Atonement (2001) and M. Zusak's The Book Thief (2007), and focuses predominantly on the roles language and literary tropes, reading and writing are shown to play in shaping not only our individual identities, memories, beliefs and perceptions but also our cultural memory and societal norms. The section dedicated to the medium of film discusses E. E. Merhige's Shadow of the Vampire (2000) and M. Scorsese's Hugo (2011) – two very different takes on the nature, magic and social impact of cinema. Within the medium of television, this doctoral thesis analyses A. Sorkin's Sports Night (1998-2000), Studio 60 on the Sunset Strip (2006-2007) and The Newsroom (2012-2014), all the while focusing especially on Sorkin's idealistic portrayal of the positive role television could play in our society as a major source of both information and entertainment if only the television industry would rally around the medium's potential. The chapters on the medium of computer games examine 2K's BioShock (2007), Yager's Spec Ops: The Line (2012) and Galactic Cafe's The Stanley Parable (2013), all three of which showcase the uniquely experiential and interactive way in which games can provide social and cultural commentary, especially on matters such as choice and agency. Finally, within the medium of online video, this study analyses H. Green's and B. Su's webseries adaption of J. Austen's Pride and Prejudice (1813), The Lizzie Bennet Diaries (2012-2013), which provides a nuanced commentary on the social significance, pitfalls and benefits of new media