280 research outputs found

    Analysis and application of digital spectral warping in analog and mixed-signal testing

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    Spectral warping is a digital signal processing transform which shifts the frequencies contained within a signal along the frequency axis. The Fourier transform coefficients of a warped signal correspond to frequency-domain 'samples' of the original signal which are unevenly spaced along the frequency axis. This property allows the technique to be efficiently used for DSP-based analog and mixed-signal testing. The analysis and application of spectral warping for test signal generation, response analysis, filter design, frequency response evaluation, etc. are discussed in this paper along with examples of the software and hardware implementation

    Cerenkov generation of high-frequency confined acoustic phonons in quantum wells

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    We analyze the Cerenkov emission of high-frequency confined acoustic phonons by drifting electrons in a quantum well. We find that the electron drift can cause strong phonon amplification (generation). A general formula for the gain coefficient, alpha, is obtained as a function of the phonon frequency and the structure parameters. The gain coefficient increases sharply in the short-wave region. For the example of a Si/SiGe/Si device it is shown that the amplification coefficients of the order of hundreds of 1/cm can be achieved in the sub-THz frequency range.Comment: 4 pages, 2 figures. Submitted to AP

    Electron-phonon interaction via Pekar mechanism in nanostructures

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    We consider an electron-acoustic phonon coupling mechanism associated with the dependence of crystal dielectric permittivity on the strain (the so-called Pekar mechanism) in nanostructures characterized by strong confining electric fields. The efficiency of Pekar coupling is a function of both the absolute value and the spatial distribution of the electric field. It is demonstrated that this mechanism exhibits a phonon wavevector dependence similar to that of piezoelectricity and must be taken into account for electron transport calculations in an extended field distribution. In particular, we analyze the role of Pekar coupling in energy relaxation in silicon inversion layers. Comparison with the recent experimental results is provided to illustrate its potential significance

    Reindustrialization and Formation of “Digital Economy”: Harmonization of Tendencies through Process of Innovative Development

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    The economy of Russia is in modern conditions at a stage of the transformation caused as shortterm trends (an exit from recession), and long-term (change of a traditional paradigm of development). The attention of authors is concentrated on tendencies of reindustrialization, development of “digital economy”, accelerations of innovative and technological development. Based on the analysis of theoretical views of these tendencies and empirical material a valid conclusion that these tendencies do not contradict each other, and can be harmonized within the state economic policy. In this regard, tools of the last demand a certain updating and improvement. Formation of the new industrial society having not only the high level of innovative and technological development, but also pronounced socio-humanistic orientation has to become a result of these transformations

    Preliminary report on taxonomical position of Vavilovia formosa (Stev.) Fed. evidenced from morphological and molecular data

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    The Fabeae Rchb. (syn. Vicieae Adans.) tribe includes numerous representatives of special agricultural value and has; therefore, received considerable attention. Despite (or because of) this, there are certain problems concerning its systematics and phylogeny. One of the most problematic groups within the tribe is the monotypic genus Vavilovia Fed. It includes very small perennial plants inhabiting the highlands of the Caucasus, Turkey, Lebanon and Iran. Although almost two centuries have passed since the first description of this plant was reported by C. Steven (more detailed information on the history of its taxonomical status is presented in (1), its status remains unresolved. Previously it was included in the genera Orobus, Lathyrus, Pisum, or treated as a separate genus, Alophotropis Grossh. or Vavilovia Fed. The most recent monographs on the family tend to describe its status as a monotypic genus including a single species, Vavilovia formosa (Stev.) Fed. (2)

    The cardio- and endothelial protective effects of ethyl methyl hydroxyl pyridine malate in modeling L-name induced nitric oxide deficiency

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    Currently, endothelial dysfunction is considered as a predictor of a number of pathologies, including arterial hypertension, ischemic heart disease, chronic heart failure, and is also a pathogenetic component of organ damage in diabetes, hypo estrogenic and other conditions. The purpose of the study is an experimental study of the cardio and vasoprotective effects of etoxidol under conditions of endothelial dysfunctio
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