1,720,971 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
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
Axonal microRNAs in cortical neuronal development and network connectivity
Get PDFCognitive brain function requires the establishment of neuronal networks, which rely on the formation and elongation and branching of axonal projections and the differentiation of presynaptic terminals during development. The cellular events involved in these processes are dependent on protein translation locally in the axon compartment, which enables rapid changes of the axonal proteome in response to neurotrophic cues to regulate axon growth and patterning. How these dynamic changes of the axonal proteome are regulated locally in the axon has been a topic of intensive investigation in the past decade. MicroRNAs are small RNAs known to regulate protein expression by controlling mRNA translation repression/degradation. Recently, these regulatory RNAs have emerged as key players in the modulation of several molecular pathways underlying neuronal differentiation in early stages of development, making this class of non-coding RNAs interesting candidate regulators of local protein translation in the axon during development. However, the role of microRNAs in the axon, in particular axonal outgrowth and presynaptic differentiation, is only beginning to be unravelled.
The work described here used next generation sequencing to identify a set of microRNAs enriched in the axonal fraction of primary cortical neurons cultured in compartmentalised microfluidic devices. Following the characterization of axonal microRNA expression levels, two microRNAs, miR-3470b and miR-99a, were selected for subsequent functional studies.
The miR-3470 family are mouse-specific repeat-derived microRNAs originating from the B1-element Mus1. Repetitive elements have a major role in shaping the structure and function of the genome, but evidence on the functional relevance of lineage-specific repeat-derived microRNAs is still limited. Inhibition of miR-3470b during early development of primary cortical neurons produced a significant decrease in axonal growth. Moreover, we discovered a significant association between miR-3470b targets and proteins involved in cell-to-cell contact/synaptic pathways. To investigate the role of miR-3470b in the formation of neuronal networks we used a microelectrode array cortical culture model, in which spontaneous electrical activity shows a progressive increase from day 9 in vitro, reflecting the establishment of functional synaptic connections. Inhibition of miR-3470b from the beginning of the third week in culture, when its endogenous levels are high, produced a marked decrease in network activity, suggesting its role in neuron connectivity during cortical neuron development.
Functional studies in cortical cultures showed that inhibition of miR-99a in primary cortical neurons produced a significant decrease in axonal growth, with overexpression of a miR-99a mimic increasing axonal length. By using bioinformatics, luciferase reporter assays and functional rescue experiments we could identify a new target for miR-99a in axonal development, heparan sulphate 3-O-sulphotransferase 2 (Hs3st2), an enzyme part of the biosynthesis of heparan sulphate proteoglycans, key players in axon-extracellular matrix interactions. To investigate the effect of axonal miR-99a in the emergence of neuron connectivity and the functioning of neuronal networks we used imaging of calcium transients to assess the spontaneous rhythmic activity of developing neuronal cultures, demonstrating how inhibition of miR-99a alters the patterns of calcium oscillation frequency and synchronicity, suggesting its relevance for network development and maturation.
Overall, this work identified two microRNAs capable of regulating axonal outgrowth in the development of mouse cortical neurons in vitro. Both microRNAs were found to exert growth promoting actions in developing axons. Furthermore, this work demonstrated the ability of mR-99a and miR-3470b to act as regulators of neuronal network formation in vitro, raising potential implications to the development of neuronal connectivity in vivo
Axonal microRNAs in cortical neuronal development and network connectivity
Get PDFCognitive brain function requires the establishment of neuronal networks, which rely on the formation and elongation and branching of axonal projections and the differentiation of presynaptic terminals during development. The cellular events involved in these processes are dependent on protein translation locally in the axon compartment, which enables rapid changes of the axonal proteome in response to neurotrophic cues to regulate axon growth and patterning. How these dynamic changes of the axonal proteome are regulated locally in the axon has been a topic of intensive investigation in the past decade. MicroRNAs are small RNAs known to regulate protein expression by controlling mRNA translation repression/degradation. Recently, these regulatory RNAs have emerged as key players in the modulation of several molecular pathways underlying neuronal differentiation in early stages of development, making this class of non-coding RNAs interesting candidate regulators of local protein translation in the axon during development. However, the role of microRNAs in the axon, in particular axonal outgrowth and presynaptic differentiation, is only beginning to be unravelled.
The work described here used next generation sequencing to identify a set of microRNAs enriched in the axonal fraction of primary cortical neurons cultured in compartmentalised microfluidic devices. Following the characterization of axonal microRNA expression levels, two microRNAs, miR-3470b and miR-99a, were selected for subsequent functional studies.
The miR-3470 family are mouse-specific repeat-derived microRNAs originating from the B1-element Mus1. Repetitive elements have a major role in shaping the structure and function of the genome, but evidence on the functional relevance of lineage-specific repeat-derived microRNAs is still limited. Inhibition of miR-3470b during early development of primary cortical neurons produced a significant decrease in axonal growth. Moreover, we discovered a significant association between miR-3470b targets and proteins involved in cell-to-cell contact/synaptic pathways. To investigate the role of miR-3470b in the formation of neuronal networks we used a microelectrode array cortical culture model, in which spontaneous electrical activity shows a progressive increase from day 9 in vitro, reflecting the establishment of functional synaptic connections. Inhibition of miR-3470b from the beginning of the third week in culture, when its endogenous levels are high, produced a marked decrease in network activity, suggesting its role in neuron connectivity during cortical neuron development.
Functional studies in cortical cultures showed that inhibition of miR-99a in primary cortical neurons produced a significant decrease in axonal growth, with overexpression of a miR-99a mimic increasing axonal length. By using bioinformatics, luciferase reporter assays and functional rescue experiments we could identify a new target for miR-99a in axonal development, heparan sulphate 3-O-sulphotransferase 2 (Hs3st2), an enzyme part of the biosynthesis of heparan sulphate proteoglycans, key players in axon-extracellular matrix interactions. To investigate the effect of axonal miR-99a in the emergence of neuron connectivity and the functioning of neuronal networks we used imaging of calcium transients to assess the spontaneous rhythmic activity of developing neuronal cultures, demonstrating how inhibition of miR-99a alters the patterns of calcium oscillation frequency and synchronicity, suggesting its relevance for network development and maturation.
Overall, this work identified two microRNAs capable of regulating axonal outgrowth in the development of mouse cortical neurons in vitro. Both microRNAs were found to exert growth promoting actions in developing axons. Furthermore, this work demonstrated the ability of mR-99a and miR-3470b to act as regulators of neuronal network formation in vitro, raising potential implications to the development of neuronal connectivity in vivo
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
