323,113 research outputs found
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
Microwave impedance properties of single crystal Ba(Fe1−XCoX)2As2
No full textThe authors reported out microwave surface impedance measurements of the optimally doped single crystal Ba(Fe 1-x Co x ) 2 As 2 (x=0.074) with critical temperature Tc =22.8K and found the power-law exponent 2.8 in temperature dependence of a field penetration depth. The obtained dependence is similar to however noticeably distinguished from radiofrequency range measurements. Thus, conclusion that nodal states are excluded in this material in favor of the extended s± pairing symmetry having a node less order parameter, becomes even more justified. The temperature dependence [ λ(0)/λ(T) ] 2 calculated for two temperature laws, namely, for a power law Δ λ(T) ~ T2.8 and exponential law for superconductor with a small gap Δ=0.73 can be an additional confirmation of the above mentioned conclusion. However the fact of proximity of two temperature laws indicates that the additional and systematic studies are necessary for establishing the unambiguous conclusion concerning temperature dependence of field penetration depth and superfluid density
Slotted-disk sapphire quasi-optical resonator with conducting endplates
No full textQuasi-optical dielectric resonator (QDR) in a form of slotted sapphire disk sandwiched between conducting endplates (CEP) is proposed and studied in Ka-band. The resonator is excited on whispering gallery modes. Mode identification of the slotted disk resonator with CEP is carried out. The measurement data are compared with simulated frequencies and Q-factors of the resonator with a copper sample under test and CEP. The calculation results are obtained using CST Microwave Studio software. The proposed and studied sapphire QDR is a promising basis for high accuracy measurements of small conducting samples (unconventional superconductors e.g. pniktides and HTS cuprates, nanotubes etc.) in millimeter wavelength range
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going 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
Millimeter-Wave Surface Impedance Characterization of HTS Films and Single Crystals Using Quasi-Optical Sapphire Resonators
No full textHigh-Q sapphire quasi-optical dielectric resonators (QDRs) excited on whispering-gallery modes are key techniques for accurate characterization in millimeter (mm) wavelength range of surface impedance of HTS large-area films and can be useful for impedance characterization of small HTS single crystals, including various unconventional superconductors. Hemispherical QDR-based technique for mm impedance characterization of HTS films is analysed theoretically and confirmed experimentally. Such an approach can be applied to QDR of modified forms. The temperature dependences of the YBaCuO films resistance properties using hemispherical resonator and the iron-pnictide single-crystal impedance properties using radially-slotted one are measured in Ka-band
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Intrinsic bistability effect in delta doped tunneling diodes / S. A. Vitusevich ; A. Förster ; B. A. Belyaev ...
No full textAuthor's address:
No full textCan archives of audiovisual TV interviews be used to make authors more visible to students, and thereby reduce the learning gap between native and non-native language speakers in college classes? We examined students in a college course who learned about one scholar's ideas through watching an audiovisual TV interview (i.e., visible author format) and about another scholar's ideas through reading a formal text description (i.e., invisible author format). For the invisible author, native language speakers scored significantly higher than the non-native language speakers on a corresponding exam question (i.e., a cognitive measure), generated more words on the exam question (i.e., a motivational measure), and mentioned the author's name more often in answering the exam question (i.e., an affective measure). For the visible author, the groups did not differ on any of these measures. These findings provide evidence for the idea that making the author visible through audiovisual TV interviews can eliminate the learning gap between native and non-native language speakers. 3 Universities around the world serve students who are non-native speakers of th
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