1,721,018 research outputs found
Leaf photosynthesis, fluorescence response to salinity and the relevance to chloroplast salt compartmentation and anti-oxidative stress in two poplars
No full textIn a 16-day study, the effect of increasing soil NaCl on leaf photosynthesis, chlorophyll a fluorescence, chloroplast ion compartmentation, variations of SOD (superoxide dismutase) and POD (peroxidase) isoenzymes and the relevance to salt resistance were investigated in seedlings of Populus euphratica Oliv. (P. euphratica) (salt-resistant) and rooted cuttings of P. “popularis 35–44” (P. popularis) (salt-sensitive). Initial salinity caused a rapid decline of net photosynthetic rate (Pn) and unit transpiration rate (TRN) in P. euphratica, resulting from the NaCl-induced stomatal closure. In a longer-term of salinity, CO2 assimilation in P. popularis was severely reduced whereas stressed P. euphratica maintained a relatively higher and constant level of Pn. Pn–Ci curves showed that salt stress (12 days) reduced CO2 saturation point (CSP), CO2 saturated Pn (CSP n ), and carboxylation efficiency (CE), but increased CO2 compensation point (CCP) in the two genotypes. Similarly, salinity lowered light saturation point (LSP), light saturated Pn (LSP n ), and apparent quantum yield (AQY) in both genotypes but the inhibitory effect of NaCl on light reaction was more pronounced in P. popularis, as compared to P. euphratica. Chlorophyll a fluorescence data indicated that a longer-term of salt stress (12 days) exhibited a marked influence on fluorescence parameters of P. popularis in both dark- and light-adapted states: (a) NaCl inhibited the maximal efficiency of PSII photochemistry (Fv/Fm) due to the salt-induced increase of Fo (the minimal fluorescence) and the marked decline of Fm (the maximal fluorescence); (b) salinity decreased coefficient of photochemical quenching (qP) but markedly elevated coefficient of nonphotochemical quenching (qN) in the light-adapted state. In contrast, there were no corresponding changes of chlorophyll a fluorescence in salinised P. euphratica. X-ray microanalysis results showed that salinity caused salt accumulation in the chloroplasts of P. popularis in which Na+ and Cl− increased up to 42 and 221 mmol dm−3, respectively. Great buildup of Na+ and Cl− in chloroplasts of P. popularis may exhibit direct and indirect restrictions on dark and light reactions. The activity of SOD isoenzymes (CuZn-SOD I and CuZn-SOD II) and POD isoenzymes in P. popularis decreased with increasing exposure period, and leaf malondialdehyde (MDA) content and membrane permeability (MP) increased correspondingly. In contrast to P. popularis, stressed P. euphratica maintained activity of SOD and POD isoenzymes and there was no significant increase of MDA and MP during the period of salt stress. In conclusion, P. euphratica plants exhibited a higher capacity to maintain the activity of anti-oxidant enzymes and restrict salt accumulation in the chloroplasts, the photosynthesis processes were less restricted consequently
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
Effect of NaCl on photosynthesis, salt accumulation and ion compartmentation in two mangrove species, Kandelia candel and Bruguiera gymnorhiza
No full textIn a 4-week study, we investigated the effects of increasing soil NaCl (100–400 mM) on photosynthesis, salt uptake and transport, and intracellular compartmentation of Na+ and Cl− in 1-year-old seedlings of Kandelia candel (L.) Druce and Bruguiera gymnorhiza (L.) Savigny. Increasing NaCl stress significantly elevated Na+ and Cl− in root and shoot tissues (stem + leaf) of both species, but B. gymnorhiza showed a rapid Na+ accumulation upon the initiation of salt stress and leaves contained 90% more Na+ and 40% more Cl− than K. candel at the end of experiment. Net photosynthetic rate (Pn) declined with increasing salinity, and the most marked reduction occurred after exposure of mangrove seedlings to a severe salinity, 400 mM NaCl. However, the inhibitory effects of severe stress varied with species: Pn decreased by 80% in K. candel whereas in B. gymnorhiza the decline was 60%. The quantum yield (AQY) and carboxylation efficiency (CE) response to severe salinity showed a trend similar to Pn, in which a lesser reduction of AQY and CE was observed in B. gymnorhiza (33–35%), as compared to K. candel (43–52%). X-ray microanalysis of leaf mesophyll cells showed evidence of distinct vacuolar compartmentation of Na+ in K. candel but Cl− in B. gymnorhiza after seedlings were subjected to 100 mM NaCl for 7 d. Moreover, Na+ within cell wall, cytoplasm, vacuole and chloroplast remained 23–72% lower in stressed B. gymnorhiza as compared to K. candel. In conclusion, B. gymnorhiza exhibited effective salt exclusion from chloroplasts although increasing salt stress caused a rapid and higher build up of Na+ and Cl− in the leaves. We suggest that the salt-induced Pn reduction in the two mangrove species is correlated with the ability to exclude Na+ and Cl− from the chloroplast, rather than with the bulk leaf salt concentration
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
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