1,721,231 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
Isomer-specific analysis of polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) in red fox and human adipose tissue from central Italy
No full textThe general exposure of humans and foxes to polychlorinated biphenyls (PCBs) and DDT in Italy was determined by analysis of adipose tissue samples collected from 1991-1992. Sigma PCB concentrations varied between 1.0 and 2.6 mu g/g (wet wt.). Sigma DDT concentrations ranged from 1.6 to 5.0 mu g/g (wet wt.). About thirty-five PCB congeners were identified in most samples. PCB congeners of IUPAC Nos. 138, 153, and 180 were the most abundant compounds, accounting for an average of 50% of the Sigma PCBs in humans and 64% in foxes. Generally, higher chlorinated biphenyls and those with a 2,4,5-chlorine substitution in one ring and at least one substitution in the 4-position of the other ring were preferentially accumulated. Coplanar PCB congeners were detected at considerable concentrations and there is no sign of decline in their concentrations with respect to previously reported data. IUPAC Nos. 118, 156 and 126 were the main contributors to toxicity in humans and foxes. The significant contribution of mono-ortho congeners in humans and non-ortho congeners in foxes suggests that differences in metabolic potential may affect the PCB toxicity pattern
Predicting the Optical Pressure Sensitivity of 2E → 4A2 Spin-Flip Transition in Cr3+-Doped Crystals
No full textUnderstanding the role played by the material chemistry to increase the pressure sensitivity of new optical pressure probes is of great scientific interest. After almost 50 years from the first proposal as an optical pressure sensor, the R-line emission of ruby (α-Al2O3:Cr3+) is still the standard pressure probe used for the diamond anvil cell experiments in worldwide laboratories. Besides the fundamental importance of developing new materials able to discriminate pressure variations with high sensitivity, the ability to predict the potentials of new materials is still a huge challenge. In this view, the pressure dependence of the R-lines in mullite-type Bi2M4O9:Cr3+ (M = Ga, Al) systems is exploited as a case study. Despite the promising performances as a pressure sensor, the mixing between 4T2 and 2E hinders the applicability of Bi2Ga4O9:Cr3+, while Bi2Al4O9:Cr3+ is characterized by a linear trend in the whole pressure range explored and a remarkable sensitivity higher than ruby. The analysis of the Cr3+-based pressure sensors in terms of crystal field, nephelauxetic effect, and bulk modulus led to a universal relationship between the pressure sensitivity and the ambient pressure 2E energy of Cr3+-doped phosphors, allowing the prediction of highly sensitive optical pressure sensors
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
Accumulation pattern of butyltin compounds in dolphin, tuna and shark collected from Italian coastal waters
No full textTributyltin (TBT) and its breakdown products, mono-(MBT) and dibutyltin (DBT) were determined in bottlenose dolphin (Tursiops truncatus), bluefin tuna (Thunnus thynnus thynnus) and blue shark (Prionace glauca) collected from the Italian coast of the Mediterranean Sea in 1992-1993. Concentrations of total butyltin (BTs) in the liver of dolphin (1,200-2,200 ng/g wet wt) were an order of magnitude higher than in the blubber (48320 ng/g wet wt). TBT was the predominant butyltin species in the blubber while DBT accounted for an higher proportion in the liver of dolphins. Butyltin concentrations in bluefin tuna were lower than those in dolphins, with TBT highest in the muscle and DBT in the liver. Concentrations of BTs in blue sharks were lower than those in dolphin and tuna, with kidney having the highest concentrations. TBT was the predominant form of butyltin derivatives in all the tissues of shark. Accumulation of butyltin compounds in liver/kidney seems to be associated with the presence of proteins such as glutathione
Pushing the Limit of Boltzmann Distribution in Cr3+-Doped CaHfO3 for Cryogenic Thermometry
No full textLuminescence Boltzmann thermometry is one of the most reliable techniques used to locally probe temperature in a contactless mode. However, to date, there is no report on cryogenic thermometers based on the highly sensitive and reliable Boltzmann-based 4T2 → 4A2/2E → 4A2 emission ratio of Cr3+. On the basis of structural information of the local HfO6 octahedral site we demonstrated the potential of the CaHfO3:Cr3+ system by combining deep theoretical and experimental investigation. The material exhibits simultaneous emission from both the 2E and 4T2 excited states, following the Boltzmann law in a cryogenic temperature range of 40-150 K. The promising thermometric performance corroborates the potential of CaHfO3:Cr3+ as a Boltzmann cryothermometer, being characterized by a high relative sensitivity (∼2%·K-1 at 40 K) and exceptional thermal resolution (0.045-0.77 K in the 40-150 K range). Moreover, by exploiting the flexibility of the 4T2-2E energy gap controlled by the crystal field of the local octahedral site, the design proposed herein could be expanded to develop new Cr3+-doped cryogenic thermometers
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