Mycoviruses are common among different species of endophytic fungi of grasses

8 páginas, 1 tabla, 1 figuraA survey of mycoviruses was made in a collection of 103 isolates belonging to 53 different species of endophytic fungi of grasses. DsRNA elements were detected in isolates of 12 of the species analyzed. The banding characteristics and sizes of some of the dsRNA elements suggest that they might belong to previously described mycovirus families. The observed incidence (22.6%) indicates that the presence of mycoviruses could be common among species of this group of ubiquitous fungi.This research was financed by project AGL2005-02839 granted by the Spanish Ministry of Science and Education. We thank Drs. Robert Coutts and Beatríz R. Vázquez de Aldana for reviewing the manuscript.Peer reviewe

Automatic selection of a subset size at vector fields construction

An algorithm for selection of the size of a correlation kernel at displacement vector field construction by the method of digital image correlation has been proposed. The algorithm has been tested on simulated and experimental optical images having different texture. The influence of the correlation kernel size and image texture on nose immunity at determining displacements has been studied. It is shown that the proposed algorithm allows to find this size providing the minimum error when determination of displacements and estimation of deformation

Ultrafast control of donor-bound electron spins with single detuned optical pulses

The ability to control spins in semiconductors is important in a variety of fields including spintronics and quantum information processing. Due to the potentially fast dephasing times of spins in the solid state [1-3], spin control operating on the picosecond or faster timescale may be necessary. Such speeds, which are not possible to attain with standard electron spin resonance (ESR) techniques based on microwave sources, can be attained with broadband optical pulses. One promising ultrafast technique utilizes single broadband pulses detuned from resonance in a three-level Lambda system [4]. This attractive technique is robust against optical pulse imperfections and does not require a fixed optical reference phase. Here we demonstrate the principle of coherent manipulation of spins theoretically and experimentally. Using this technique, donor-bound electron spin rotations with single-pulse areas exceeding pi/4 and two-pulses areas exceeding pi/2 are demonstrated. We believe the maximum pulse areas attained do not reflect a fundamental limit of the technique and larger pulse areas could be achieved in other material systems. This technique has applications from basic solid-state ESR spectroscopy to arbitrary single-qubit rotations [4, 5] and bang-bang control[6] for quantum computation.Comment: 15 pages, 4 figures, submitted 12/2008. Since the submission of this work we have become aware of related work: J. Berezovsky, M. H. Mikkelsen, N. G. Stoltz, L. A. Coldren, and D. D. Awschalom, Science 320: 349-352 (2008

Призрак советского человека

The article restores the theoretical logic behind Yuri Levada and his team's research project, "Soviet Man". Based on the project's publications, the article reconstructs both the "early" model, which included a set of attitudes toward the "antinomies" of the Soviet system, as well as the later model which emphasized a set of adaptive characteristics ("adapted", "two-faced", etc.). The empirical and theoretical foundations that prompted the authors of the project to abandon the original hypothesis about the "disappearing type" of the Soviet man are clarified. There is a connection between the dynamics of the "Soviet Man" project and the early theoretical works of Yuri Levada in the 1970s and 1980s; specifically, there is a shift in his interests from structural analysis to action problems. The theoretical prerequisites of the critical texts of the Levada of the post-Soviet period (the concepts of "social change", "degenerate case") are clarified. The role of the general methodological guidelines of the Levada group is emphasized: "transposing" the concepts of Western sociology in describing the Soviet / Russian case; elucidating the historical context in which the terms arose; attempting a comparison with the "generalized West", the obligatory linking of research tasks to the "big problems" of their society Possibilities of updating ("reverse transposing") the theoretical developments of Levada within the framework of the academic community that does not share the basic methodological principles of the project are discussed. As possible topics for academic discussion, a comparison of the conceptions of modernization in the USSR -introduced by Levada and the late Parsons in the System of Modern Societies - is proposed, as well as the possibilities of the Levada's concept for explaining and predicting social changes across generations

Spin relaxation of localized electrons in n-type semiconductors

The mechanisms that determine spin relaxation times of localized electrons in impurity bands of n-type semiconductors are considered theoretically and compared with available experimental data. The relaxation time of the non-equilibrium angular momentum is shown to be limited either by hyperfine interaction, or by spin-orbit interaction in course of exchange-induced spin diffusion. The energy relaxation time in the spin system is governed by phonon-assisted hops within pairs of donors with an optimal distance of about 4 Bohr radii. The spin correlation time of the donor-bound electron is determined either by exchange interaction with other localized electrons, or by spin-flip scattering of free conduction-band electrons. A possibility of optical cooling of the spin system of localized electrons is discussed.Comment: Submitted to the special issue "Optical Orientation", Semiconductor Science and Technolog

Spin relaxation in low-dimensional systems

We review some of the newest findings on the spin dynamics of carriers and excitons in GaAs/GaAlAs quantum wells. In intrinsic wells, where the optical properties are dominated by excitonic effects, we show that exciton-exciton interaction produces a breaking of the spin degeneracy in two-dimensional semiconductors. In doped wells, the two spin components of an optically created two-dimensional electron gas are well described by Fermi-Dirac distributions with a common temperature but different chemical potentials. The rate of the spin depolarization of the electron gas is found to be independent of the mean electron kinetic energy but accelerated by thermal spreading of the carriers.Comment: 1 PDF file, 13 eps figures, Proceedings of the 1998 International Workshop on Nanophysics and Electronics (NPE-98)- Lecce (Italy

Organizational-Economic Trends and Urgent Problems of Digitalization of the Economy of the Republic of Kazakhstan

The purpose of this scientific article is to identify modern trends in the formation of the economic and organizational foundations for the development of the digital economy of the Republic of Kazakhstan, to identify the main problems in these areas and ways to solve them. The main initial data for writing a scientific article were official statistical information in the field of development of communications and information and telecommunication technologies, scientific periodicals, including the near and far abroad, practical data of entrepreneurial structures directly leading production and economic activities in the digital and computer technology. The hypothesis of scientific research is the need to form the institutional foundations for building a digital economy, focused on the implementation of infrastructural development of digitalization processes at the macro and micro levels. The institutional framework affects both the public sector and the business entrepreneurship sector. In the strategic period for the development of the digital economy, indicative programs for business structures, as well as organizational scenarios for the state, should be developed. The main methods of scientific research were analytical and synthetic, statistical, computational, and analytical research methods, the method of hypotheses. As the results of the study, attention was focused on the dynamics of the contribution of digitalization processes to the economic growth of the Republic of Kazakhstan, and the main economic problems that hinder the intensification of the development of the digital economy were identified. The main scientific contribution of the study is focused on the priorities for solving the problems of digitalization of the economy within the strategic and long-term periods, including micro- and macroeconomic levels

Trends in the Development of Social Responsibility of Business Organizations in Kazakhstan

The article is devoted to developing the institutional framework for the social responsibility of business in the Republic of Kazakhstan. The object of the study is business organizations represented by small, medium, and large enterprises. The subject of the study is the organizational and economic foundations of social responsibility. The purpose of this study is to analyze the trends of social responsibility, identify problems, priorities for building this institution. The following methods were used as research methods: analytical, statistical, computational-analytical, and dialectical-search methods. The study is based on data for the strategic period 2016-2020, separate data for 2010 and 2015. The study showed that the participation of enterprises in the development of the social sphere is in its infancy. The mechanisms of social responsibility are characteristic of large enterprises, an important role belongs to the state. Social responsibility does not meet international standards. Social responsibility-oriented standards are not used enough in the business environment. In the labor market, there are tendencies to reduce real wages, which reduces the degree of social responsibility. The formed mechanisms of social responsibility do not create conditions for developing the social sphere, or the development of human potential, which does not contribute to economic growth. In the future, the organizational and economic mechanisms of social responsibility of large corporations, small and medium-sized businesses at the micro, meso and macro levels should be improved. The study was discussed at scientific seminars at Toraigyrov University with the participation of economists, representatives of the state and businesses

Di-chromatic InGaN based color tuneable monolithic LED with high color rendering index

We demonstrate a phosphor free, dichromatic GaN-based monolithic white LED with vertically stacked green and blue emitting multiple quantum wells. The optimal thickness of GaN barrier layer between green and blue quantum wells used is 8 nm. This device can be tuned over a wide range of correlated color temperature (CCT) to achieve warm white (CCT = 3600 K) to cool white (CCT = 13,000 K) emission by current modulation from 2.3 A/cm2 to 12.9 A/cm2. It is also demonstrated for the first time that a color rendering index (CRI) as high as 67 can be achieved with such a dichromatic source. The observed CCT and CRI tunability is associated with the spectral power evolution due to the pumping-induced carrier redistribution

AlGaInP red-emitting light emitting diode under extremely high pulsed pumping

Efficiency of commercial 620 nm InAlGaP Golden Dragon-cased high-power LEDs has been studied under extremely high pump current density up to 4.5 kA/cm2 and pulse duration from microsecond down to sub-nanosecond range. No efficiency decrease and negligible red shift of the emission wavelength is observed in the whole range of drive currents at nanosecond-range pulses with duty cycles well below 1%. Analysis of the pulse-duration dependence of the LED efficiency and emission spectrum suggests the active region overheating to be the major mechanism of the LED efficiency reduction at higher pumping, dominating over the electron overflow and Auger recombination