1,721,028 research outputs found
Nanocrystalline CsPbBr3 Thin Films: a Grain Boundary Optoelectronic Study
No full textRecently ternary compounds of CsPbX3 (X=Cl, Br, I) produced by co-evaporating CsX and PbX2 purified powders are attracting much interest for their interesting optical characteristics and potential applications in luminescence based detector and devices. Indeed, nano-crystallites are produced in the thin film material as evidenced by optical spectroscopy and X-Ray diffraction. These ternary nano-aggregates are wide-gap semiconductors with direct band-to-band transition. Identification of the nano-crystallites in the film is based on a similarity of the observed spectroscopic properties with those of the bulk CsPbX3 purified by the Bridgman technique. The materials object of this study have been deposited by Physical Vapour Deposition inside an UHV apparatus on DC7059 optical glass starting from CsBr and PbBr2 purified powders or by crushing Bridgman crystals. In this paper, we report on an impedance spectroscopy study in a wide frequency range (10-5 107 Hz) and temperature (100-650 K) aimed to identify the distribution of surface related electronic defects. Moreover, transient photoconductivity measurements in the sub-nanosecond range have then been performed to infer the role of these defects on the charge carriers recombination mechanism and mobility-lifetime product
Electron and hole trapping in Eu- or Eu,Hf-doped LuPO4 and YPO4 tracked by EPR and TSL spectroscopy
No full textEPR spectroscopy in X- and Q-bands was employed to trace charge carrier trapping upon exposure to X-rays of LuPO4:Eu, LuPO4:Eu,Hf and YPO4:Eu,Hf flux-grown single crystals, as well as LuPO4:Eu sintered ceramics. These data were complemented with thermoluminescence (TL) studies on the same compositions. EPR spectra proved that all the single crystals contained Pb impurity incorporated from the flux. Upon exposure to X-rays the concentration of Pb3+ changed proving that Pb participated in carrier trapping. The ionizing radiation caused also partial conversion of Eu3+ into Eu2+ and in the (Eu,Hf) doubly doped crystals also Hf4+ was transformed into Hf3+ upon exposure to X-rays. In the LuPO4:Eu sintered ceramics X-rays transformed Eu3+ into Eu2+ and the strong EPR signal of a hole trapped at O2- in the vicinity of a defect (presumably Lu3+-vacancy) was recorded. Some contribution from the PO42- molecular ion could also be observed. However, in crystals the EPR signal from the latter was much more intense compared to the former. In ceramics, the trapped hole was found to hop between the O2- ions and only below similar to 70 K it localized at just one of them. Complementary measurements of TL of the samples showed meaningful differences between the glow curves of the crystals and of the ceramics. The TL glow curve of the latter contained only one band peaking around 120 degrees C which is related to destruction of the trapped hole being mainly the O- center. All single crystals showed multi-peak TL glow curves covering the range of 30-500 degrees C. They were found to result mainly from a hole released from the PO42- molecular complex and to some extent also from the O- center. The results relative to EPR and TL spectroscopy proved that in orthophosphates Eu3+ is an effective electron trapping center while holes may be trapped at impurity ions, like Pb2+, or localized at oxygen ions possibly stabilized by nearby defects, e.g. Lu-vacancie
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Deployment of corporate audio-video technology
No full textThis thesis deals with the possibility of connecting, automating and controlling audio/video hardware. In the theoretical part the author deals with input and output A/V devices, A/V interfaces communication interfaces, possibility of connecting automation elements and a room control. It explains terms relating to the audio/video topic.
The practical part suggests a complete design and implementation of a showroom to present the portfolio of Colsys company, which demonstrates functions of the control system Crestron, such as controlling projectors, video matrices, sound equipment and building automation (lights, air conditioning, blinds, etc.). First part of this section deals with defining the requirements for individual devices. The next step was the selection of suitable components based on fulfilling the set criteria and the budget. After that a check of compatibility was performed and room layout was designed, which contained electrical layout and a room blueprint. Final step of this section was designing the user interface and its realization in order to create the control unit program.
Based on the theoretical part the author created a chapter titled Recommendation, which is verified in the practical part by creating a fully functional showroom for Colsys company, which also serves as a meeting room
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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