1,720,965 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
Exploring the Metabolic Intersection of Juglone and Phylloquinone Biosynthesis
No full textJuglone is a 1,4-naphthoquinone (1,4-NQ) and the allelochemical responsible for the well-known toxic effects of black walnut (Juglans nigra) and other members of the Juglandaceae. Juglone affects a variety of weed species via a mode of action unlike any commercially available herbicides, and thus has the potential to be used as a new natural product-based herbicide. However, lack of knowledge about its metabolism precludes introducing juglone biosynthesis traits into resistant crops through biotechnology. Herein, we established that juglone is derived from the phylloquinone pathway at the level of the intermediate 1,4-dihydroxy-2-naphthoic acid (DHNA). Phylloquinone is a primary 1,4-NQ made by all plants for photosynthetic electron transport. Despite the fundamental importance of phylloquinone, there are still unanswered questions about the subcellular architecture of the phylloquinone pathway. In chapter 3, we show that osuccinylbenzoate CoA-ligase is localized to both chloroplasts and peroxisomes and that its activity is vital in both organelles. The required dual localization of CoA ligase activity is a theme common to other plant pathways with CoA metabolic steps occurring in peroxisomes and thus leads us to propose a revised model of the phylloquinone pathway. Lastly, given the potential of introducing juglone biosynthesis as part of novel weed management strategies, we investigated the circumstances, costs, and benefits of producing allelochemicals in crops using an evolutionary game theory model. Together, this work (i) shows that the phylloquinone pathway provides crops with the biosynthetic framework to produce juglone, (ii) sheds new light on the phylloquinone pathway architecture, and (iii) reveals the circumstances in which producing an allelochemical will be an evolutionarily stable strategy. We envision these results will assist biotechnological efforts to utilize juglone as a novel, natural product-based herbicide
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
Discovery of Cytosolic Phenylalanine Biosynthetic Pathway in Plants
No full textPhenylalanine
(Phe) is a proteinogenic aromatic amino acid that also serves as a precursor
for numerous primary and secondary metabolites in plants. Phe is synthesized
from chorismate, the final product of the shikimate pathway. In plants, Phe is predominantly
synthesized in the plastids via the arogenate pathway, while most Phe-derived
compounds are produced in the cytoplasm, requiring exportation of Phe from
plastids to the cytosol. Here, we provided genetic evidences that a Petunia hybrida plastidial cationic
amino acid transporter (PhpCAT) participates in the exportation of Phe from
plastids, as well as regulation of carbon flux through Phe biosynthesis.
By using reverse genetics, we demonstrated
that a petunia phenylpyruvate aminotransferase (PhPPY-AT) is able to convert
phenylpyruvate to Phe in the cytosol in
vivo, and that a cytosolic chorismate mutase (CM2), which converts
chorismate to prephenate, directs carbon flux from the plastidial Phe
biosynthesis pathway towards the cytosolic pathway. Downregulation of PhPPY-AT and PhCM2 resulted in significant decreases in Phe levels and emission
of Phe-derived volatiles in petunia flowers, respectively. Metabolic flux
analysis showed that the carbon flux through the cytosolic Phe biosynthesis
pathway is significantly lower in PhCM2
RNAi petunia flowers relative to wild type control. We also demonstrated that
the conversion of prephenate to phenylpyruvate in the cytosol is catalyzed by a
cytosolic prephenate dehydratase (PDT) produced from an alternative
transcription start site of a known plastidial arogenate dehydratase (ADT). These
results suggest that a microbial-like phenylpyruvate pathway for Phe
biosynthesis operates in the cytosol of plant cells and the cytosolic pathway
splits from the plastidial pathway at chorismate.
To evaluate the metabolic potential of
the cytosolic phenylpyruvate pathway, PhCM2
overexpressing transgenic petunia plants were generated. Unexpectedly, Phe
levels and emission of Phe-derived volatiles were both reduced, even though the
flux through the cytosolic pathway was increased relative to wild type control.
Electron microscopy, metabolic profiling and metabolic flux analysis revealed
that the number of leucoplasts, starch levels and flux through the plastidial
pathway were all reduced in PhCM2
overexpression lines, while the concentrations of auxin and its biosynthetic
intermediate, indole-3-pyruvic acid (IPA), were elevated. Overexpression of
Arabidopsis aminotransferase VAS1, which converts IPA to Trp, in PhCM2 overexpression petunia background
recovered Phe levels and Phe-derived volatiles emission. These results indicate
that there exists a metabolic crosstalk between cytosolic Phe production and
Trp-dependent auxin biosynthesis .
Our research completed the
post-chorismate cytosolic Phe biosynthesis pathway in plants and revealed
possible metabolic crosstalk between cytosolic Phe production and auxin
biosynthesis in plant cells, providing targets for future genetic modification
of metabolites in plants.</p
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
