1,721,078 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Impact tolerance of thermoplastic and thermoset epoxy carbon textile composites
Full text linkRecently, a thermoplastic epoxy resin (TP-EP) was developed with both advantages of thermoset and thermoplastic resins. The TP-EP has the good workability of TS and the formability and recyclability of TP. The present study aims to assess the impact tolerance of the TP-EP carbon textile composite (CFRTP) compared to the thermoset epoxy resin (TS-EP) counterpart. Drop weight impact test, with a hemispherical striker tip were performed for different molecular weight (Mw) of the TP-EP matrix. An impact energy of 30J was selected for comparison. The impact damage extension was visualized by a thermal-camera and by laser microscope measurements. The residual mechanical strength after impact was measured by compression tests. The highly polymerized CFRTP had higher maximum impact force, lower energy absorbed ratio, lower residual dent and smaller damaged surface, meaning a better impact tolerance
3D reconstruction of structures of hatched larva and young juvenile of the larvacean Oikopleura dioica using SBF-SEM
Full text linkThe larvacean Oikopleura dioica is a planktonic chordate and an emerging model organism with a short life cycle of 5 days that belongs toTunicata (Urochordata), the sister clade of vertebrates. It is characterized by the rapid development of a tadpole-shaped body. Organ formation in the trunk proceeds within 7 h after the hatching of the tailbud larvae at 3 h after fertilization (hpf) and is completed at 10 hpf, giving rise to fully functional juveniles as miniature adult form. Serial block face scanning electron microscopy was used to acquire ~ 2000 serial transverse section images of a 3 hpf larva and a 10 hpf juvenile to characterize the structures and cellular composition of the trunk and organs using 3D images and movies. Germ cells were found to fuse and establish a central syncytial cell in the gonad as early as 10 hpf. Larval development gave rise to functional organs after several rounds of cell division through trunk morphogenesis. The feature would make O. dioica ideal for analyzing cellular behaviors during morphogenetic processes using live imaging. The detailed descriptions of the larvae and juveniles provided in this study can be utilized as the start and end points of organ morphogenesis in this rapidly developing organism
Low velocity impact and CAI of woven carbon fibre reinforced highly polymerized thermoplastic epoxy modified with submicron diameter glass fibres
Full text linkThe experimental study aimed to understand the effect of the highly polymerized thermoplastic epoxy matrix and of the submicron diameter glass fibres content on the impact and compression after impact (CAI) performance of woven carbon fibre reinforced composites. A thermoset epoxy system was also considered for the sake of comparison. The comparison highlighted the better impact performance of the composites with the thermoplastic epoxy matrix of higher weight-average molecular weight (Mw), which is further improved by the proper content of micro glass fibres. The enhanced impact damage tolerance was also demonstrated observing the damage imparted with surface laser morphology, infrared thermography and X-ray μ-CT
CARBON TEXTILE REINFORCED HIGHLY POLYMERIZED THERMOPLASTIC EPOXY: EFFECT OF SUBMICRON GLASS FIBRES ON THE IMPACT RESPONSE
No full textThe primary factors affecting the impact damage tolerance of composite materials are the characteristics of the resin and the fiber, the fiber/matrix interface and the reinforcement architecture. The resin and textile reinforcement are the topics of this work. A thermoplastic epoxy resin (TP) was developed coupling the advantages of thermoset and thermoplastic resins. It has the workability of thermoset resins and the formability and recyclability of thermoplastic systems. In previous study, this thermoplastic epoxy was adopted for manufacturing textile carbon fiber composites. The effect of the weight-average molecular weight (Mw) was investigated, and results highlighted improved tensile strength, longer tensile-tensile fatigue life, and enhanced fracture toughness (mode I and II). The fracture toughness driven by the properties of the TP epoxy matrix could suggest a better impact performance. Over the past decades, to enhance the impact behavior of composite materials, research efforts were dedicated to improving the toughness of resins by dispersion of nano- or micro- sized fillers. This strategy was adopted in the present work. The highly polymerized thermoplastic epoxy matrix was modified with submicron diameter glass fibers (0.1% and 0.3% in weight of resin), and then adopted as matrix of woven carbon fiber composites. For the sake of comparison, a thermoset epoxy system (TS) was considered. Drop weight impact test was performed, and the impact damage extension was observed by laser microscope morphology, thermal measurements, and X-ray μ-CT. The residual mechanical strength after impact was measured by compression tests. Overall, the high Mw TP composites, unmodified and 0.3% modified matrices, had the better impact performance with smooth and more ‘ductile’ post peak impact behavior and lower level of absorbed energy than the TS counterparts. The damage distribution confirmed the better damage tolerance of the 0.3% modified high Mw TP composites, having: a reduced dent depth, an almost uniform distribution of the surface temperature, a lower crack density and interlaminar delamination, and shorter transverse crack paths thought the thickness. This was the effect of the matrix toughness and the bridging action of micro glass fibers. As for the retention of compressive strength, the high Mw TP composites, modified with 0.3% of submicron diameter glass fibers, significantly suppressed the reduction of strength after impact (retention of about 91%)
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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