1,722,440 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
Valutazione del potenziale angiogenico di cellule mesenchimali staminali adulte derivate dalla polpa dentaria umana
Full text linkDental pulp has been revealed as an accessible and a rich source of mesenchymal stem cells (MSCs) and its biological potential is currently under intense investigation. MSCs from dental pulp stem cells (DPSC) have been indicated as a heterogeneous population oriented not only in repairing dentine but also in maintaining vascular and nervous homeostasis of the teeth. We sought to verify the phenotype of cells isolated from dental pulp of young donors and to investigate in vitro their role as pericyte-like cells. Specifically, we evaluated how different culture conditions can modulate expression of pericyte markers in DPSC and their capacity to stabilize endothelial tubes in vitro. DPSC cultured in standard conditions expressed MSC markers and demonstrated to contain a population expressing the pericyte marker NG2. These DPSC were associated with low sprouting capacity in extracellular (EC) Matrix and limited ability in retaining tubes formed by endothelial cells in a coculture angiogenesis model. When cultured in endothelial growth medium (EGM-2), DPSC significantly upregulated NG2. The resulting population conserved the stem marker CD73 but was negative for calponin and endothelial markers. EGM-2-conditioned DPSC showed a higher sprouting ability in EC Matrix and efficient association with human umbilical vein endothelial cells allowing the partial retention of endothelial tubes for several days. Among growth factors contained in EGM-2 we identified basic fibroblast growth factor (FGF) as mainly responsible for NG2 upregulation and long-term stabilization of endothelial tubes. According to the in vitro analysis, DPSC represent an effective source of pericytes, and the appropriate culture conditions could result in a population with a promising ability to stabilize vessels and promote vascular maturation
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
New media e spazi di democrazia partecipativa nella società dell’Informazione: il caso cinese
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Geografie contemporanee del centro storico. Spazi (ir)reali, nuove funzioni e city-users in una metropoli mediterranea
No full textOptical and electrical characterizations of graphene nanoplatelet coatings on low density polyethylene
No full textCoatings of graphene nanoplatelets (GNPs) were deposited on a low density polyethylene (LDPE) substrate by a micromechanical method based on rubbing graphite platelets against the surface of the polymer. Transmission electron microscopy measurements reveal that the coatings were composed of nanoplatelets containing 13-30 graphene layers. Thermal gravimetric analysis shows that the investigated GNP coatings on LDPE (GNP/LDPE) samples are thermally stable up to 250 °C. Optical spectra of these samples, compared to those of pristine LDPE in the ultraviolet-visible-near-infrared range, indicate an increase in both reflectance and absorptance. On the other hand, the coating is able to markedly improve the surface conductivity of the polymeric substrate, indeed in the case of electrical contacts in the coplanar configuration (1 cm long and spaced 1 mm), the resistance of LDPE is 1015Ω, while that of GNP/LDPE is 670 Ω. Electrical measurements under white light illumination point out a decrease in the conductance and a linear behavior of the photoconductance as a function of the optical power density. GNP/LDPE materials can be used for their optical, electrical, thermal, and flexibility properties in large area plastic electronics and optoelectronics. © 2017 Author(s)
Distorted f.c.c. arrangement of gold nanoclusters: a model of spherical particles with microstrains and stacking faults
No full textThe structures of two samples of gold nanoclusters supported on silica were
studied by X-ray powder diffraction (XRD) and X-ray absorption spectroscopy.
The data relative to both techniques were analysed by an approach involving
simulation based on structural models and fitting. The XRD model concerned a
distorted f.c.c. (face-centred cubic) arrangement, with microstrains and parallel
stacking faults in approximately spherical particles; as an alternative possibility,
a linear combination of ordered f.c.c. and noncrystalline (decahedral and
icosahedral) particles was also taken into account. Both approaches gave
calculated patterns closely resembling the experimental data. X-ray absorption
spectra were fitted on the basis of f.c.c. and noncrystalline arrangements. The
best results were obtained by the f.c.c. motif, while a simulation consisting in the
superposition of f.c.c. and noncrystalline components in the relative amounts
determined by XRD analysis gave a poor agreement with the experimental data.
It was concluded that the good XRD fitting obtained by linear combination of
lognormal size-distributed f.c.c. cuboctahedral, decahedral and icosahedral
contributions was a result of the flexibility of the basis set of functions, but that
the complementary analysis of X-ray absorption data did not confirm the
presence of a noteworthy fraction of noncrystalline particles
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