1,720,966 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
TOWARD POTENT ANTIBIOFILM DEGRADABLE MEDICAL DEVICES: GENERIC METHODOLOGIES FOR THE SURFACE MODIfiCATION OF POLYLACTIDE
No full textSurface post-modification of polylactide is combined
to CuAAc click chemistry or thiol-yne click
photochemistry to yield antibiofilm surfaces.
INTRODUCTION
As a direct result of the life expectancy increase,
implants are increasingly used for the restoration of
human anatomy and functions. However, this is
accompanied with the development of biomaterialassociated
septic failures1. To limit these risks, the
modulation of the antibacterial surface properties of
prosthetic materials appears therefore as a convenient
and efficient strategy. In this frame, postpolymerization
modification approaches, especially
click chemistry, have attracted much attention in the last
decade2. In this communication, we wish to report on
the recent post-modification strategies developed by our
group to yield polylactide antibacterial surfaces.
EXPERIMENTAL METHODS
PLA surfaces were activated via anionic chemical
modification to anchor alkyne moieties, according to a
reaction previously described by our group3. This
clickable PLA intermediate was then engaged in two
distinct strategies. In a first approach, well-controlled
quaternized PDMAEMA chains (5-10 kDa) with an
azide chain-end were synthesized and covalently
grafted to the PLA clickable surfaces by CuAAc 1,3-
dipolar cycloaddition. In a second approach, cationic
derivatives of α,β-poly(N-2-hydroxyethyl)-aspartamide
(PHEA) were functionalized with lipoic acid (LA).
Photoactivated thiol-yne reaction was done under UV
by reacting PHEA-LA at the surface of the clickable
PLA in the presence of TCEP. All polymers have been
characterized by NMR and SEC analyses. After careful
washes, surfaces were analysed by AFM and XPS.
Antibacterial activity was tested against four bacterial
strains. Adherence of bacteria and biofilm formation
were tested. Cytocompatibility was evaluated with L929
fibroblasts. All data are expressed as means ± SD and
correspond to measurements in triplicate.
RESULTS AND DISCUSSION
Thanks to the use of optimized and mild activation
conditions, alkyne functionalized PLA surfaces were
obtained without degradation as already reported
elsewehere6. CuAAc cycloaddition of QPDMAEMA
chains was evaluated by XPS and showed an overall
10% coverage of the PLA surface by QPDMAEMA. No
residual copper was detected. Activity was strong
against all bacterial strains, including E. Coli and S.
Aureus with a clear dependence of the antibacterial
activity over QPDMAEMA molecular weight and
alkylating agent (Figure 1). Best results were obtained
for Mn = 10 000 g/mol and heptyl group with adherence
reduction factors > 99.999% (ASTM E 2149–01) and
strong bactericidal activity.
Fig. 1. Antibacterial activity of antibacterial PLA surface (red bars)
against four bacterial strains. PLA plates are shown as control (brown
bars).4
With short reaction times and no metals used, UV
photoactivated thiol-yne grafting of PHEA-LA was
studied as a green alternative to CuAAc.
Advantageously, the heterogeneous surface reaction
took place in aqueous media. Various solvent mixtures
were tested and best results were obtained in slightly
acidic water/ethanol (1:1) medium, in the presence of
TCEP and with a 15 min irradiation time per PLA plate
side. Under these conditions, XPS confirmed the
covalent grafting of the cationic PHEA-LA derivative.
As for CuAAc, antibacterial and antibiofilm activities
were tested with again reduction factors > 99.999% and
up to 80% biofilm decrease for all four bacterial strains.
Interestingly, whatever the methodology used all
surfaces showed a good cytocompatibility towards
L929 fibroblasts cells with respect to TCPS control.
CONCLUSION
Antibacterial PLA surface modification was obtained in
an efficient two steps approach by combining anionic
and click chemistries. For the first time green thiol-yne
strategy was applied to PLA surfaces, which paves the
way to further developments in the biomedical field.
REFERENCES
1. Campoccia D. et al. Biomaterials 34:8018-8029, 2013
2. Theato P. & Klok H-A. Eds. Wiley-CH, 2013
3. El Habnouni S. et al. Adv. Funct. Mater. 21:3321-3330, 2011
4. El Habnouni S. et al. Acta Biomater. 9 :7709-7718, 2013
ACKNOWLEDGMENTS
Authors thank the French MESR for PhD fundings
TOWARD POTENT ANTIBIOFILM DEGRADABLE MEDICAL DEVICES: GENERIC METHODOLOGIES FOR THE SURFACE MODIfiCATION OF POLYLACTIDE
No full textDispelling 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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