Quasiparticle density of states in Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} single crystals probed using tunneling spectroscopy at ultra-low temperatures in high magnetic fields

Break-junction tunneling spectroscopy at temperatures 30-50 mK in high magnetic field is used to directly probe the quasiparticle density of states within the energy gap in a single crystal Bi2212 high-$T_c$ superconductor. The measured tunneling conductances $dI/dV(V)$ in the subgap region have a zero flat region with no evidence for a linear increase of the density of states with voltage. A number of tunnel break-junctions exhibited $dI/dV(V)$ curves with a second energy gap structure at the average magnitude 2$\Delta _{p-p}/e=13$ mV. Our data cannot be explained by either a pure $s$ pairing or a pure $d_{x^2-y^2}$ pairing

Metal-to-insulator crossover and pseudogap in single-layer compound Bi2+x_{2+x}Sr2−x_{2-x}Cu1+y_{1+y}O6+δ_{6+\delta} single crystals in high magnetic fields

The in-plane $\rho_{ab}(H)$ and the out-of-plane $\rho_c(H)$ magneto-transport in magnetic fields up to 28 T has been investigated in a series of high quality, single crystal, hole-doped La-free Bi2201 cuprates for a wide doping range and over a wide range of temperatures down to 40 mK. With decreasing hole concentration going from the overdoped (p=0.2) to the underdoped (p=0.12) regimes, a crossover from a metallic to and insulating behavior of $\rho_{ab}(T)$ is observed in the low temperature normal state, resulting in a disorder induced metal insulator transition. In the zero temperature limit, the normal state ratio $\rho_c(H)/\rho_{ab}(H)$ of the heavily underdoped samples in pure Bi2201 shows an anisotropic 3D behavior, in striking contrast with that observed in La-doped Bi2201 and LSCO systems. Our data strongly support that that the negative out-of-plane magnetoresistance is largely governed by interlayer conduction of quasiparticles in the superconducting state, accompanied by a small contribution of normal state transport associated with the field dependent pseudogap. Both in the optimal and overdoped regimes, the semiconducting behavior of $\rho_c(H)$ persists even for magnetic fields above the pseudogap closing field $H_{pg}$. The method suggested by Shibauchi \textit{et al.} (Phys. Rev. Lett. \textbf{86}, 5763, (2001)) for evaluating $H_{pg}$ is unsuccessful for both under- and overdoped Bi2201 samples. Our findings suggest that the normal state pseudogap is not always a precursor of superconductivity.Comment: 11 pages, 8 figures, published in PRB Nov 200

СОЦІОКУЛЬТУРНІ ПОГЛЯДИ АКАДЕМІКА В.П.ФІЛАТОВА У СВІТЛІ НЕВІДОМИХ ДОКУМЕНТІВ РАДЯНСЬКИХ СПЕЦСЛУЖБ (до 140-ї річниці з дня народження вченого)

On the basis of known operational broad scientific public documents of the Soviet state security highlights the socio-cultural world views and features prominent ophthalmologist scientist and public figure, academician VP Filatov. Based on the evidence of the scientist studied the place of the Orthodox faith in the system of professional, cultural and ethical beliefs and activities organizer renowned surgeon and medical science in Ukraine.Vladimir Filatov (10/27/1875 p. – 10.30.1956 g.) Academician of the Academy of Medical Sciences and the Academy of Sciences of the Ukrainian entered the history of medicine as prominent ophthalmologist, physicians, surgeon, researcher and innovator, educator and founder of solid scientific eye school, aut over 460 scientific papers. He was born in province of Penza, and  linked life and productive activities of medical Ukraine, in 1903 until his death working in Odessa.Tireless work of the world-renowned scientist was awarded the title Hero of Socialist Labor, State (Stalin) Prize in the field of science and technology, a number of awards, including the Order of the Patriotic War, combat and degree for labor in emergency hospital during the confrontation with Nazi aggression, large gold Mechnikov medal. It was founded in 1946 "ophthalmologic journal". He was elected a deputy of the Supreme Soviet of 4 convocations (since 1938). Now the name of the scientist is Research Institute of Eye Diseases and Tissue Therapy named after Filatov Sciences of Ukraine, which he created and led the stretch in 1936.Against the background of significant scientific works on research activities and major milestones biography V.P.Filatova remains virtually unexplored range of social and cultural values and philosophical views of the scientist. Meanwhile, we found recently in the archives of the secret intelligence materials serve as a productive source for playback comprehensive intellectual biography of academician Filatov, contain a lot of information about the spiritual, cultural, moral, intellectual world prominent scientist.In addition to Soviet reality nonconformist views on problems of political life, the scientist played the original carrier of the socio-cultural attitudes, looking busy solving complex cultural and ethical issues related to the ratio of the spiritual world, personal manners and proper professional and social activities. However, only now the attention of researchers are beginning to attract sociocultural view this extraordinary figure who harmoniously combined selfless service to rescue people with active social work, participation in the life of the Orthodox Church, classes in painting and the formation of scientific schools, the participants of which instilled and "Filatov" coordinates cultural and ethical world view.Archives Soviet intelligence suggest large undercover surveillance by relentless V.P.Filatovym academician, his professional and personal environment, which was due as clearly anti-communist convictions and religious scholar, and its weight in the scientific and public life, aspirations to foreign intelligence research TECHNOLOGICAL development scientist. These documents are interrogation V.Filatova, serve as productive (although biased, specific) source study his biography and activities established the Research Center of Ophthalmology. Despite ideological differences, outstanding ophthalmologist created the right conditions and protection from arbitrary repressive system, with simultaneous half insulation of international scientific cooperationAn outstanding scientist and physician, being a deeply religious, traditionalist conservative-minded in ideological and spiritually, abhorrence took violent rise to power of the Bolsheviks, a bloody civil war and foreign intervention. He is a lifetime concealed his religious beliefs, anticommunist views and sharply critical attitude to socio-political actions of the Soviet government, Stalin's repressions, especially painfully perceived shameful policy of destroying Orthodox Church, militant atheism and brutal destruction of churches, the oppression of freedom of speech and scientific creativity, restrictions scientific ties with foreign colleagues. V.Filatov was a true patriot of his homeland, because for him even incompatible ideological views of official and personal harassment by the authorities have not caused the exile (which he repeatedly offered to interested foreign medical and other institutions). The documents state security recognized that in 1919, in the midst of the Civil War, V. Filatov said those who urged him to evacuate abroad that social revolution was necessary to overthrow the tsarist regime, and he prefers to work at home for the benefit of the people and very indignant those intellectuals fleeing into exile.В статье на основе неизвестных широкому научному кругу оперативных документов советских органов государственной безопасности освещаются социокультурные взгляды и особенности мировоззрения выдающегося ученого-офтальмолога и общественного деятеля, академика В.П. Филатова. На основе свидетельств самого ученого исследуется место православной веры в системе профессиональных и культурно-этических взглядов, а также в деятельности известного организатора медицинской науки в Украине.У статті на основі невідомих широкому науковому загалу оперативних документів радянських органів державної безпеки висвітлюються соціокультурні погляди та особливості світогляду видатного вченого-офтальмолога і громадського діяча, академіка В.П. Філатова. На підставі свідчень самого вченого досліджується місце православної віри у системі професійних та культурно-етичних поглядів та діяльності знаного хірурга і організатора медичної науки в Україні

3D-melting features of the irreversibility line in overdoped Bi2_2Sr2_2CuO6_6 at ultra-low temperature and high magnetic field

We have measured the irreversible magnetization of an overdoped Bi$_2$Sr$_2$CuO$_6$ single crystal up to B=28 T and down to T=60 mK, and extracted the irreversibility line $B_{\rm irr}(T)$: the data can be interpreted in the whole temperature range as a 3D-anisotropic vortex lattice melting line with Lindemann number $c_{\rm L}=0.13$. We also briefly discuss the applicability of alternative models such as 2D- and quantum melting, and the connection with magnetoresistance experiments.Comment: M2S-HTSC-VI Conference paper (2 pages, 1 figure), using Elsevier style espcrc2.st

In-plane current-voltage characteristics and oscillatory Josephson-vortex flow resistance in La-free Bi2+x_{2+x}Sr2−x_{2-x}CuO6+δ_{6+\delta} single crystals in high magnetic fields

We have investigated the in-plane $I(V)$ characteristics and the Josephson vortex flow resistance in high-quality La-free Bi$_{2+x}$Sr$_{2-x}$CuO$_{6+\delta}$ (Bi2201) single crystals in parallel and tilted magnetic fields at temperatures down to 40 mK. For parallel magnetic fields below the resistive upper critical field $H^{*}_{c2}$, the $I(V)$ characteristic obey a power-law with a smooth change with increasing magnetic-field of the exponent from above 5 down to 1. In contrast to the double-layer cuprate Bi2212, the observed smooth change suggests that there is no change in the mechanism of dissipation (no Kosterlitz-Thouless transition) over the range of temperatures investigated. At small angles between the applied field and the $ab$-plane, prominent current steps in the $I(V)$ characteristics and periodic oscillations of Josephson-vortex flow resistance are observed. While the current steps are periodic in the voltage at constant fields, the voltage position of the steps, together with the flux-flow voltage, increases nonlinearly with magnetic field. The $ab$-flow resistance oscillates as a function of field with a constant period over a wide range of magnetic fields and temperatures. The current steps in the $I(V)$ characteristics and the flow resistance oscillations can be linked to the motion of Josephson vortices across layers

Search for Magnetic Field Induced Gap in a High-Tc Superconductor

Break junctions made of the optimally doped high temperature superconductor Bi2Sr2Ca2CuO8 with Tc of 90 K has been investigated in magnetic fields up to 12 T, at temperatures from 4.2 K to Tc. The junction resistance varied between 1kOhm and 300kOhm. The differential conductance at low biases did not exhibit a significant magnetic field dependence, indicating that a magnetic-field-induced gap (Krishana et al., Science 277 83 (1997)), if exists, must be smaller than 0.25 meV.Comment: 3 pages, 2 figure

КУЛЬТУРНО-ІНФОРМАЦІЙНИЙ ВПЛИВ СУЧАСНОГО СВІТУ ТА ІСТОРИЧНА СВІДОМІСТЬ УКРАЇНСЬКОЇ ПОЛІТИЧНОЇ НАЦІЇ

The influence of cultural, information and psychological processes of globalization on the functioning of historical memory mechanisms in Ukraine is considered. Recommendations regarding scientific support of the historical memory formation and development state policy, which would include the scientific, cultural and educational, memorial segments, are made.Research and origin of the functioning of Historical Memory (historical consciousness) became one of the leading areas of world and national historiosophical opinion interdisciplinary subject of serious research. Globalization caused massive scale out social, political and economic activity beyond the borders of individual states and nations on intercontinental level. Unheard of increased intensity of the relationships in the exchange of goods, investments, financial operations, migration, cultural and information processes. Much easier movement of people and process information. Globalization has in many ways become a logical consequence of humanity – and Interstate block integration collapse of the colonial system and a new type of networking between former colonies and metropolises, weight increase industrial cooperation and open new resource bases in remote parts of the world developed countries, improvement material culture under the influence of the STR, the development of transport and communications, the Internet.It is worth noting that the analysis of the essence of globalization is generally taken into account the economic and communication factors, while globalization means a significant challenge to traditional cultures of the world. Conducted since the end of the 1990s. Number of leading international think tank study on the impact of the information revolution transformation processes of modern society BASED even cried when a new geopolitical concept, which is based on the thesis of the "digital divide" nations, which arose during the information revolution and globalization of the world economy. One of the most important phenomena of the spiritual life of people who are affected unifikatsiynyh effects of globalization is the historical memory of the peoples (nations) as part of their national consciousness and statehood. In modern ethnology approved the submission of historical consciousness factor as one of the key levers of creation of modern nations. Historical memory BASED treads important part of identity and the consolidation of the peoples inhabiting the Ukraine, a single political nation (civic community) – Ukrainian people. Restoring and preserving the collective memory of the state-creating traditions, civilizational achievements, military and labor victory, historical tragedy promotes unity citizenship and mobilizing spiritual forces and potential builders Ukrainian nation, its establishment as an equal subject of international relations, the preservation of public order and territorial integrity of Ukraine, creation of positive socio-political, moral and cultural field being Ukrainian political nation.The term "historical memory" refers to the phenomenon of social consciousness, selectively stored nation body of knowledge, ideas and value assessments of the events of the past that had a decisive influence on its formation, identity, and state-civilizational achievements and consensus in society are perceived as the most important for its self-existence of a consolidated and constructive development in the future. Accordingly, the policy content of the historical memory of the Ukrainian state, are motivated, normalized with constitutional and legal point of view, science-based efforts of the state and society, aimed at identifying, preserving, strengthening in the public mind the memory of the most important reproduction and political life of the nation events and processes of the past in the interest of the sovereign state of civilization and progress. Given the globalization of modern world, the powerful development of electronic and other media, technologies and methods of influence on mass consciousness (including manipulating her destructive information and psychological impact) is markedly increasing scale of threats to information security and stability component of the Ukrainian state. The use of technologies targeted information-psychological influence in modern conditions can lead to such disastrous consequences for sovereign statehood that previously achieved direct aggression or coup.During the period of development of Ukraine as a sovereign state politics of historical memory as part of humanitarian policy was created largely situational, exposed to political conditions, corporate interests. Its foundation was laid not acceptable to society, scientifically based enshrined in regulatory principles and guidelines concerning the development and implementation of national memory as a focused and continuous set of measures developed and implemented by the authorities.Рассматривается неоднозначное воздействие культурно-информационного влияния глобализации на функционирование механизмов исторического сознания как важной составляющей идентичности украинской политической нации, а также на традиционную культуру Украины. Высказываются рекомендации относительно научного обеспечения государственной политики формирования и развития исторической памяти, которая включала бы научный, культурно-просветительский, мемориальный и другие сегменты.Розглядається неоднозначне позначення культурно-інформаційних впливів глобалізації на функціонування механізмів історичної свідомості як важливої складової ідентичності української політичної нації, а також на традиційну культуру України. Висловлюються рекомендації щодо наукового забезпечення державної політики з формування і розвитку історичної пам’яті, яка включала б науковий, культурно-просвітній, меморіальний та інші сегменти

Flutter of aircraft panels at low supersonic flight speeds

Abstract Flutter of panels can be of two possible types: single mode or coupled mode type of flutter. Coupled mode flutter has been thoroughly studied using piston theory, which represents air pressure acting on the plate. Single mode flutter cannot be studied using piston theory and requires potential flow theory or more complex aerodynamic theories. This type of flutter occurs at low supersonic Mach numbers and is studied insufficiently. In this paper a comprehensive numerical investigation of single mode flutter is conducted. Flutter boundaries and their transformations with change of the problem parameters are studied

Bursts of extensive air showers: chaos vs. stochasticity

Bursts of the count rate of extensive air showers (EAS) lead to the appearance of clusters in time series that represent EAS arrival times. We apply methods of nonlinear time series analysis to twenty EAS cluster events found in the data set obtained with the EAS-1000 prototype array. In particular, we use the Grassberger-Procaccia algorithm to compute the correlation dimension of the time series in the vicinity of the clusters. We find that four cluster events produce signs of chaos in the corresponding time series. By applying a number of supplementary methods we assess that the nature of the observed behaviour of the correlation dimension is likely to be deterministic. We suggest a simple qualitative model that might explain an origin of clusters in general and "possibly chaotic" clusters in particular. Finally, we compare our conclusions with the results of similar investigations performed by the EAS-TOP and LAAS groups.Comment: An extended version of the paper to be submitted to Astroparticle Physics. Version 2: 22 pages, discussion extended, the main part shortened, accepted for publication. Version 1 is still valid (up to a number of typos