1,720,998 research outputs found
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
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
Surface potential mapping, characterization and modelling of the threshold voltage shift in organic field-effect transistors
No full textProbing dynamic interfaces in organic electronics
Get PDFOrganic semiconductors are emerging in solar cells, photodetectors, light-emitting diodes and field-effect transistors. The main advantages are the electrical transport properties that can be tailored by chemical design, and their mechanical flexibility. Applications are foreseen in the field of large-area organic electronics, where numerous discrete devices are required on low-cost substrates such as glass or plastic. Widespread introduction however is hampered by two main bottlenecks, which are the limited operational stability and the complex formulations needed for the large-area processing. The basic building block of organic electronics is the field-effect transistor; a microelectronic device used to manipulate the magnitude of a current with an external electrical field. Transistors have to be reliable under operation i.e. when biases are applied to the electrodes, the resulting device current should be constant. In organic transistors however, the on-current slowly decreases with time, an effect of which the origin is unknown. This so-called bias-stress-effect has puzzled the scientific community for more than two decades. In chapter 2 it was shown that the decrease of current with time is caused by a shift of the threshold voltage, i.e. the bias needed to turn the transistor on. The temperature dependence of the threshold voltage shift is determined to be independent of the semiconductor used. This observation led to the conclusion that the threshold voltage shift is due to a common physical origin, but the exact nature remained elusive. Additional measurement techniques were required to understand the cause of the threshold voltage shift. In chapter 3 scanning Kelvin probe microscopy (SKPM) was used to monitor trapped charges in transistors under applied bias. SKPM measures the local surface potential and provides microscopic insight in the electrical performance of organic transistors. It was shown that the potential profiles changed upon gate bias stress, but only in the channel region of the transistor. The reliability issues were found to be not due to an increase in the contact resistance, but due to trapping of charges in the channel area of the transistor. The question remained where the charges were trapped exactly. The threshold voltage shift could be due to trapping in the semiconductor or in the gate dielectric. In chapter 4 SKPM proved that charges can be stored at the dielectric-semiconductor interface even without a semiconductor present. By exfoliating the semiconductor after stress, and subsequent probing of the surface potential of the exposed gate dielectric, it was shown that the threshold voltage shift was indeed due to charge trapping in the dielectric and not in the semiconductor. In chapter 5 a scenario is proposed to explain the observed threshold voltage shift quantitatively. The model consists of two ingredients: (i) hole-assisted electrolytic production of protons from water in the accumulation layer and (ii) the subsequent diffusion of these protons into the SiO2 gate dielectric. The proposed model captures the most important features of the gate bias stress effect, such as the time dependence of the threshold voltage shift and the semiconductor-independent temperature dependence of the threshold voltage shift. The model can also explain the recovery of the transistor upon grounding all electrodes and predicts an anomaly in the current transients, which was experimentally verified in chapter 5. By combining the experimental and theoretical evidence as presented in this thesis, it was concluded that a layer of water at the gate dielectric together with diffusion of protons into the gate dielectric can explain the most important features of the bias stress effect. At the moment large area processing, like evaporation and spin coating, is top-down. A promising process technology for organic electronics is bottom-up self-assembly, which is the autonomous organization of components into patterns and structures without human intervention. Self-assembly has the advantage over conventional processing techniques that it can be made substrate selective and can potentially cover large areas uniformly. Self-assembled monolayers (SAMs) gained a great scientific and industrial interest because of their ability to change the macroscopic properties of surfaces by a single sheet of molecules. Reported surface modifications are for instance changes in workfunction, wettability and adhesion. The advances in SAM-based electronics however have been slow. To investigate the possibility of self-assembly as a processing tool to fabricate organic electronics, first a well-studied system - thiols on gold - was considered in chapter 6. Thiols with opposite built-in dipole moment were chosen and in this way the workfunction of the injecting electrode could be increased as well as decreased. The change in workfunction resulted in a modification of the current injection. In this way patterned light-emitting diodes (LEDs) were fabricated. Only a single layer of molecules determined the light emission in an organic LED. The expertise gained on self-assembly in organic electronics was used to fabricate self-assembled monolayer electronics in chapter 7. Making integrated circuits using a bottom-up approach involving self-assembling molecules was already proposed in the 1970s. The basic building block of such an integrated circuit is the self-assembled monolayer field-effect transistor (SAMFET), where the semiconductor is a monolayer spontaneously formed on the gate dielectric. In SAMFETs fabricated so far, current modulation has only been observed in sub-micrometer channels. Low field-effect carrier mobility, low yield and poor reproducibility have prohibited the realization of bottom-up integrated circuits. We were able to identify and remove these bottlenecks by studying the charge injection and transport in monolayer semiconductors. By circumventing the main roadblocks, real logic functionality was demonstrated in integrated circuits by constructing a 15-bit code generator in which hundreds of SAMFETs were addressed simultaneously. Additionally, we investigated the cause of the absence of current in long channel length transistors. The extracted device mobility in SAMFETs was found to be determined by the monolayer coverage and the channel length. The dependence on coverage and channel length were quantitatively explained numerically and analytically. At partial coverage, SAMFETs form a unique model system to study charge percolation in two dimensions. The SAMFETs were made with silicon dioxide as the gate dielectric, which could be a possible disadvantage when they are used as building blocks in flexible electronics. As a final step the self-assembly process was transferred to organic substrates in chapter 8, which yielded fully functional 4-bit code generators based on organic dielectrics
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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