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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
Age-related changes of cell outgrowth from calvarial and mandibular bone in vitro
No full textAIM:
To establish whether within an autograft ageing has an impact on the number of cells capable of responding to growth and differentiation factors released at defect sites.
MATERIAL AND METHODS:
The number of cells that grow out from calvarial and mandibular explants of rats 6 weeks and 9 months of age was evaluated and their response to mitogenic, chemotactic, and differentiation factors was characterized in vitro. The cell number was determined by automated counting, proliferation was evaluated by measuring the amount of (tritiated) (3)[H]thymidine incorporated into the DNA, and migration was assessed with the modified Boyden chamber assay. Alkaline phosphatase activity served as a marker of osteogenic differentiation.
RESULTS:
A confluent layer of cells was observed in mandibular and calvarial explant cultures derived from young rats within 10 days, while only sporadic cells were counted in cultures from adult animals. The number of cells derived from calvarial and mandibular bone of young rats was nine and five times higher, respectively, than that in explants from adult rats. Cells isolated from calvarial and mandibular explants responded to platelet-released supernatant by increased proliferation and migration in both age groups. Upon incubation with bone morphogenetic protein (BMP-6), the alkaline phosphatase activity of calvaria-derived cells from both age groups was higher than in unstimulated controls. Only one sample of cells derived from mandibular explants showed responsiveness to BMP-6 in the young age group, whereas none of the cell samples responded to BMP-6 in the adult age group.
CONCLUSION:
The number of cells capable of growing out from mandibular and calvarial grafts in vitro is lower in adult animals than in young animals. However, bone-derived cells from both young and adult rats respond to growth and differentiation factors present at defect sites, while there are topographic differences in the responsiveness to BMP-6
Bone marrow stromal cells from young and adults rats similar respond to platelet released supernatant and BMP-6 in vitro
No full textBackground: Age-related changes in periodontal bone regeneration, osseointegration of dental implants, and graft consolidation are increasingly considered in treatment planning. This study was intended to show whether aging is associated with a diminished responsiveness of osteoprogenitor cells to growth and differentiation factors. Methods: We compared the capacity of bone marrow stromal cells harvested from young and adult rats to proliferate, migrate, and differentiate into the osteogenic lineage following exposure to platelet-released supernatant (PRS) or bone morphogenetic protein-6 (BMP-6). Bone marrow stromal cells were isolated from 12 young rats aged 6 weeks and 12 adult rats aged 9 months. Proliferation was assessed by 3[H]thymidine incorporation, migration was evaluated with the Boyden chamber assay, and osteogenic differentiation was deduced from alkaline phosphatase activity. Results: Irrespective of the donor age, bone marrow stromal cells showed increased mitogenic activity and chemotactic motility when exposed to PRS. Adult bone marrow stromal cells had higher alkaline phosphatase activities at baseline and upon incubation with BMP-6 than cells obtained from young animals. There was no difference between the two groups in the slope of the alkaline phosphatase activity curve following stimulation with BMP-6. Conclusions: The data demonstrate that, irrespective of their age, bone marrow stromal cells respond similarly to PRS and BMP-6 under in vitro conditions. These findings suggest that osteoprogenitor cells within the bone marrow of adult rats retain their juvenile potential to respond to growth and differentiation factors, which are released naturally or are applied therapeutically at sites of bone regeneration
Cathepsin K levels in crevicular fluid of dental implants
No full textObjective: To determine the concentration of cathepsin K secreted into the crevicular fluid around dental implants and its correlation with clinical parameters of healthy implants and implants showing clinical signs of peri-implantitis. Material and Methods: Nineteen patients with 40 implants with and without peri-implantitis were enrolled in the study. Peri-implantitis was diagnosed by the pocket probing depth (PD), the modified bleeding index (MBI), the modified plaque index (MPI) and by radiographic signs of bone loss. Gingival crevicular fluid collected from the buccal and lingual sites was adsorbed to filter strips. Cathepsin K levels and total protein within the crevicular fluid were determined by immunoassay and the bicinchoninic method, respectively. Results: Cathepsin K per filter strip normalized to the time of collection was 10.1 (0-33.5) pmol/sample around control implants and 22.4 (3.7-56.3) pmol/sample in the peri-implantitis group. The difference between the medians was significant (p<0.01). Absolute cathepsin K levels in the crevicular fluid of all implants investigated showed a positive correlation with PD (R=0.25; p=0.03), MPI (R=0.28; p=0.01) and MBI (R=0.32; p<0.01). Absolute cathepsin K levels in the crevicular fluid also correlated with the adsorbed volume of gingival crevicular fluid (R=0.51; p<0.01). When normalized to the adsorbed volume of gingival crevicular fluid, the concentration of cathepsin K was 2.2 (0.01-6.4) nM around control implants and 1.7 (0.4-4.6) nM in the peri-implantitis group (p=0.33). Patients' age correlated with sample volume and with cathepsin K normalized to the adsorbed volume of gingival crevicular fluid (R=0.39; p<0.01). Moreover, significant differences between male and female (p<0.01, p<0.01), and between mandible and maxilla (p<0.05, p<0.01), but not between buccal and lingual sites (p=0.99, p=0.93), were observed when analysed for the parameters adsorbed volume and absolute cathepsin K levels. Conclusion: Clinical parameters of peri-implantitis are associated with a higher amount of cathepsin K and a higher volume adsorbed to filters strips. To establish cathepsin K as a biochemical parameter to monitor peri-implant tissue health, age, sex and collection site should be considered to avoid interfering influences because of sample inhomogenity. Also a prospective study over time including more patients would be necessary
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
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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