262,697 research outputs found
TEACHER MASTER – I. M. PROTSENKO
No full textThis article was written about Ivan Matveevich Protsenko as a tribute to the teacher, one of the dancers, who occupies a prominent place in the dance industry. The article lifs up life of I.M. Protsenko, his first steps in the art of dance and his achievements over the years. His role in the dance pedagogy, his educational and creative activities are analyzed from a scientific point of view
Lethrus (Autolethrus) tshatkalensis Protsenko 1965
No full text<i>Lethrus</i> (<i>Autolethrus</i>) <i>tshatkalensis</i> Protsenko, 1965 <p> <i>Lethrus</i> (<i>Autolethrus</i>) <i>tshatkalensis</i> Protsenko, 1965: 14, Figs. 1, 2a–k.</p> <p>Two paratypes are deposited in NMPC (ex coll. V. Balthasar):</p> <p>PARATYPE (J): ‘Čatkalskoj chrebet / V. 63 / Kirgizia mer. [hw] // Det. Procenko [hw] // ex coll. V. Balthasar / National Museum Prague / Czech Republic [p] // Paratypus [p, red label] // Lethrus tshatkalensis Proc. [hw, white label, black margin]’.</p> <p>PARATYPE (♀): ‘Kirgizia m. / Čatkalskoj ch. / V. 63 [hw] // ex coll. V. Balthasar / National Museum Prague / Czech Republic [p] // Paratypus [p, red label]’.</p> <p> <b>Current status.</b> <i>Lethrus</i> (<i>Lethrus</i>) <i>tshatkalensis</i> Protsenko, 1965 – see e.g., NIKOLAJEV (2003).</p>Published as part of <i>Bezděk, Aleš, Hájek, Jiří & Ascr, Biology Centre, 2009, Catalogue of type specimens of beetles (Coleoptera) deposited in the National Museum, Prague, Czech Republic, pp. 297-332 in Acta Entomologica Musei Nationalis Pragae 49 (1)</i> on page 308, DOI: <a href="http://zenodo.org/record/5319147">10.5281/zenodo.5319147</a>
HTS Microstrip Resonators Excited on WGM and Fundamental Mode: Q-Factor
No full textFor effective technological implementation of HTS-based microstrip resonators, it is of practical interest to study and to compare the dissipative properties of two types of such resonators: excited on whispering gallery modes (WGM) and resonators excited at the fundamental frequency. The analysis was performed in the frequency range from 1.5 GHz to 40 GHz. By using numerical simulation of partial Q-factors it is shown that the value of Q-factor at a temperature of 77 K and lower for the YBa2Cu3O7-delta - based WGM resonator without housing exceeds the Q-factor for the resonator exited with a fundamental mode with housing in the frequency range from 1.5 to 35 GHz. This is an important practical result. The experimental data and the results of numerical simulations are mutually consistent. In the millimeter wavelength range, when the dimensions of traditional resonators become unacceptably small, it will be more convenient to use microstrip WGM resonators
Noiseless amplification in cavity-based optical systems with an internal two-photon process. II. Self-frequency-doubling laser and second-harmonic generation, self-down-converting laser
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Quantum fluctuations in multimode semiconductor lasers
No full textWe derive a quantum macroscopic model for a multimode semiconductor laser, starting from a complete microscopic description. Nonlinear gain terms describing saturation and mode-mode interaction are obtained by a suitable treatment of the spectral hole burning in the distribution of carriers. In the case in which there are two neighbouring active longitudinal modes above threshold and for quiet pumping, we calculate the spectrum of the total intensity fluctuations at zero frequency. For moderate pumping level the nonlinear gain terms do not reduce the degree of anticorrelation between modes, leaving the squeezing in total intensity unchanged with respect to the single-mode case. Only for very high pumping does the nonlinear gain suppression become relevant, and the total intensity noise is increased
Cavity solitons in driven VCSELs above threshold
No full textCSs have been theoretically predicted and recently experimentally demonstrated in broad area, vertical cavity, driven semiconductor lasers (VCSELs) slightly below the lasing threshold. Above threshold, the simple adiabatic elimination of the polarization variable is not correct, leading to oscillatory instabilities with a spuriously high critical wave-number. To achieve real insight on the complete dynamical problem, we study here the complete system of equations and find regimes where a Hopf instability, typical of lasers above threshold, affects the lower intensity branch of the homogeneous steady state, while the higher intensity branch is unstable due to a Turing instability. Numerical results obtained by direct integration of the dynamical equations show that writable/erasable CSs are possible in this regime, sitting on unstable background
Cavity soliton laser based on VCSEL with saturable absorber
No full textWe study theoretically a broad-area vertical cavity surface emitting laser (VCSEL) with a saturable absorber. We show numerically the presence of cavity solitons in the system: they exist as solitary structures formed through a modulationally unstable homogeneous lasing state that coexists with a background with zero intensity. Such a peculiar scenario endows the solitons with unique properties compared to cavity solitons in most previously studied optical systems. In particular, these solitons do not as such rely on a proper phase of the addressing pulses to be either created or deleted. We show that exciting and deleting the solitons depend crucially on whether a threshold in the soliton peak has been reache
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