1,720,988 research outputs found
JAR1-mediated JA-Ile accumulation: a mechanism towards drought stress resistance in <em>Arabidopsis thaliana</em>
Full text linkIn the present work, the regulatory capacity of biologically active jasmonate, jasmonyl-isoleucine (JA-Ile), under normal and progressive drought stress conditions throughout a plant’s life-cycle was investigated. To alter endogenous JA-Ile levels, two different plant lines were used: i) the T-DNA insertion line jar1-11, which contains significantly reduced amount of JA-Ile and ii) complementary to this, a T-DNA insertion line (JAR1-OE) expressing JAR1.1-YFP under the control of the 35S promoter, which results in JAR1 overexpression and enhanced endogenous JA-Ile levels. This line was newly developed within this work. Both lines displayed difference in growth and stress resistance compared to the wild type and each other. Under normal growth conditions jar1-11 plants displayed a larger rosette with narrower leaf blades, while JAR1-OE plants had stunted growth with lateral leaves. And while JAR1-OE was late in flowering, a reciprocal trend was observed in jar1-11. Furthermore, jar1-11 plants were more susceptible to drought stress, while JAR1-OE plants were highly resistant. In line with the difference in JAR1, hormone analysis revealed increased accumulation of JA-Ile in JAR1-OE under drought, while jar1-11 accumulated JA that could not be converted to JA-Ile. In addition, the homeostasis of some precursors and highly abundant catabolic products of JA and JA-Ile were differentially affected in these lines. Global gene expression analysis by RNA-seq revealed a reprogramming of the jasmonate signaling pathway with a positive feedback upregulation in JAR1-OE under drought stress. By contrast, in jar1-11 the biosynthesis of jasmonates was inhibited. Positive feedback in JAR1-OE helps plants to acquire pre-stress tolerance with positive stomatal regulation, anti-oxidant activity and modulation of ABA biosynthesis. This ultimately helps the plants in coping with subsequent drought stress through regulation of the photosynthetic machinery and other biological processes. Furthermore, calmodulin-like protein 12 (CML12) was identified as a potential target of jasmonate signaling. Intriguingly, CML12 behaves differentially at the transcriptional and translational levels to the presence or absence of JAR1 or endogenously added JA-Ile supporting a potential cross-talk between jasmonate and Ca2+-signaling. Finally, the transcription factor AtMYB2 was found to be a regulator of jasmonate signaling as it could control the accumulation of JA and JA-Ile under normal growth as well as drought stress conditions
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
High-Performing and Fire-Resistant Biobased Epoxy Resin from Renewable Sources
No full textEpoxy resins with high thermal and mechanical performance as well as good resistance to fire are difficult to synthesize. In this work, a high-performance intrinsically flame-retardant epoxy resin (diglycidyl ether of daidzein (DGED)) was synthesized from renewable daidzein using an efficient one-step process, without the addition of additional flame retardants. The structure of DGED was confirmed by Fourier transform infrared (FTIR), H-1 NMR, and C-13 NMR before it was cured with 4,4'-diaminodiphenylmethane (DDM). A commercial diglycidyl ether of bisphenol A (DGEBA) was cured with the same curing agent. Results indicated that the cured DGED/DDM system possessed glass transition temperature (T-g) of up to 205 degrees C (172 degrees C for DGEBA/DDM), and tensile strength, tensile modulus, flexural strength, and flexural modulus of 83, 2972, 131, and 2980 MPa, respectively, all much higher than those of cured DGEBA/DDM. The cured DGED/DDM system demonstrated excellent flame-retardant properties, showing a residual char of 42.9% at 800 degrees C, limiting oxygen index (LOI) of 31.6%, and flammability rating of V-0 in UL94 test. This work provides us an efficient method to prepare high-performance epoxy resin from renewable resource
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
High-Performing and Fire-Resistant Biobased Epoxy Resin from Renewable Sources
No full textEpoxy resins with high thermal and mechanical performance as well as good resistance to fire are difficult to synthesize. In this work, a high-performance intrinsically flame-retardant epoxy resin (diglycidyl ether of daidzein (DGED)) was synthesized from renewable daidzein using an efficient one-step process, without the addition of additional flame retardants. The structure of DGED was confirmed by Fourier transform infrared (FTIR), H-1 NMR, and C-13 NMR before it was cured with 4,4'-diaminodiphenylmethane (DDM). A commercial diglycidyl ether of bisphenol A (DGEBA) was cured with the same curing agent. Results indicated that the cured DGED/DDM system possessed glass transition temperature (T-g) of up to 205 degrees C (172 degrees C for DGEBA/DDM), and tensile strength, tensile modulus, flexural strength, and flexural modulus of 83, 2972, 131, and 2980 MPa, respectively, all much higher than those of cured DGEBA/DDM. The cured DGED/DDM system demonstrated excellent flame-retardant properties, showing a residual char of 42.9% at 800 degrees C, limiting oxygen index (LOI) of 31.6%, and flammability rating of V-0 in UL94 test. This work provides us an efficient method to prepare high-performance epoxy resin from renewable resource
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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