1,721,044 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
Mechanical testing protocols as performance indicators for glass-ionomers
No full textTHESIS 11038The aim of the current investigation was to identify a reproducible and discriminatory
mechanical testing methodology to act as a performance indicator for glass-ionomers (GIs).
The investigation is presented as a series of manuscripts. The dental literature was reviewed
to highlight developments in GI powder and liquid constituents since their inception and
adoption into the dental field in the early 1970\u27s (Manuscript 3.1)
The strengthening of resin cemented dental ceramic materials
No full textTHESIS 10298The aim of the current investigation was to advance the understanding of the mechanism of resin-strengthening conferred to dental ceramic materials by resin-based composite materials. The investigation is presented as a series of manuscripts. In the first study (Manuscript 3.1), dental porcelain disc-shaped specimens were resin-coated with three resin-based composite materials with different flexural moduli at discrete resin thicknesses. The discs were loaded to failure in a biaxial flexure test and the maximum tensile stress calculated with an analytical solution to determine the magnitude of resin-strengthening. Linear regression techniques were utilised to identify the theoretical strengthening at a \u27zero\u27 resin-coating thickness. A finite element analysis model was employed to verify the analytical solution and validate the experimental data. The tlexural modulus and thickness of the resin-based composite materials were observed to have a significant impact on the magnitude of resin-strengthening. A soda lime glass analogue material for dental porcelain was identified to reduce the variability associated with specimen preparation (Manuscript 3.2). The study examined the influence of pre-cementation operative variables (alumina particle air abrasion and HF acid-etching) and resin-cement coating on the biaxial flexure strength of the soda lime glass analogue for dental porcelain. The soda lime glass analogue demonstrated the same patterns of strength dependence influenced by pre-cementation parameters and resin-cementation variables characterised previously for dental porcelain. Load to failure testing of dental ceramic materials is typically performed at a constant standardised testing rate
Biocompatibility of non-precious dental casting alloys : development of novel testing mechanisms
No full textTHESIS 9658The aim of the present investigation was to investigate the biocompatibility potential of commercially available non-precious dental casting alloys facilitated by multiple analyses using a two-dimensional (2D) oral keratinocyte (TR146) cell monolayer structure and a novel three-dimensional (3D) human-derived, full-thickness, differentiated oral mucosal model. The first section of the study aimed to determine the influence of the surface finishing condition of a Ni-based (d.Sign? 10) dental casting alloy on the biocompatibility potential. The biocompatibility was determined following direct and indirect exposure of the dental casting alloys to the 2D oral keratinocyte cell monolayer structures. The clinically relevant polished dental casting alloys induced significantly increased adverse biological effects compared with the ?as-cast? alumina particle air abraded alloys. In addition, the study showed that the use of trypsin-edetate disodium (EDTA) was inappropriate in the determination of the TR146 cell density measurements and highlighted difficulties for comparisons with trypsin-EDTA-treated cell density studies in the dental literature. The biocompatibility potential of two polished Ni- based (d.Sign? 10 and d.Sign? 15) and a cobalt-chromium (Co-Cr) (d.Sign?30) dental casting alloy were investigated on the 2D TR146 cell monolayer structure and compared using multiple analyses. The d.Sign? 15 dental casting alloy was shown to elicit significantly increased adverse morphological and physiological responses from the 2D TR146 cell monolayer structures compared with the d.Sign?10 alloy and the Co-Cr (d.Sign?30) alloy. The influence of oral microorganisms (Streptococcus mutans, Candida albicans and Candida dubliniensis) on the biocompatibility potential of the dental casting alloys was also determined using the 2D TR146 cell monolayer structure. Oral microorganisms were shown to enhance the loss of biocompatibility, possibly due to the decreased pH levels, which exacerbated metal ion leachate release levels from the alloys
Effects of montmorillonite clay addition on the compressive fracture strength and wear resistance of glass-ionomer restoratives
No full textTHESIS 8917The aim of the present investigation was to investigate the influence of montmorillonite (MMT) clay, both as-found (un-modified calcium montmorillonite (Ca-MMT)) and pre-treated to encourage exfoliation (organically-modified MMT clay 12-amino-dodecanoic acid treated-montmorillonite (ADA-MMT)), on the compressive fracture strength, elastic modulus and in vitro wear resistance of a variety of commercial GI restorative products. Firstly, the MMT clays were added to the powder and liquid constituents of an anhydrous GI restorative (Chemfil Superior) at concentrations ranging from 0.5 to 2.5 wt.% (in 0.5 wt.% increments). Groups of 30 or more cylindrical specimens (6 mm height, 4 mm diameter) were prepared and the mean compressive fracture strength was determined. The in vitro wear resistance was assessed for groups of eight disc-shaped specimens using the OHSU oral wear simulator operating at 20 N abrasion and 90 N attrition forces for 50,000 cycles at a frequency of 1 Hz in the presence of a poppy seed and PMMA bead slurry. The addition of Ca-MMT clay to Chemfil Superior resulted in a steady decrease in the mean compressive fracture strength and in vitro wear resistance with increasing Ca- MMT clay concentration. Adding ADA-MMT clay to Chemfil Superior (at concentrations ranging from 0.25 to 1.25 wt.%) resulted in significant increases in the mean compressive fracture strength and in vitro wear resistance compared with the control. As a result, ADA-MMT clay was also added (at concentrations of 0.5 and 1.0 wt.%) to the powder and liquid constituents of a variety of conventional GI restoratives consisting of a separate glass containing powder and a polyalkenoic acid liquid solution. In general the addition of ADA-MMT clay to the powder and liquid constituents of the conventional GI restoratives did not increase the mean compressiv
The efficacy of irradiation protocol and irradiation distance on resin-based composite performance
No full textTHESIS 8600The objective of the current study was to investigate the efficiency of the overlapping irradiation regime for resin-based composites (RBCs) in ISO 4049 by modifying the irradiation protocol. To exacerbate the potential for uncontrolled initiation on polymerisation and decrease the homogeneity of polymerisation along the length of the specimen, the exit window was moved by three-quarters (not half) the diameter along the top surface only so that some areas received twice the irradiation of adjacent areas. It was proposed that increasing the number of irradiations, with decreasing tip diameter from 13 to 11 and 8mm, would progressively decrease the efficiency of the polymerisation process compared with a ?one-hit? irradiation using a 25mm custom made fibre optic light guide. Additionally, the influence of light irradiation variables (tip diameter, irradiance, irradiation protocol and LCU) on the flexural strength, flexural modulus and the Vickers hardness were assessed. Within the limitations of the experiment tip diameter, irradiance and irradiation protocol had no influence on three-point flexural strength and modulus data. An increase in irradiance for a constant irradiation time resulted in an increase in the Vickers hardness of the bottom surfaces. The study emphasised that the relationship between the development of mechanical properties with energy density is not linear although some clinical implications were highlighted. The objective of Part II of the current study was to investigate RBC placement variables (principally irradiation distance) which has implications for strength and modulus development in clinical practice. In addition, the influence of quartz tungsten halogen LCU irradiation distance on bi-axia! flexure strength and short- and long-term in-vitro wear resistance were als
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
- …
