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Morphological and physiological responses of cowpea (Vigna unguiculata (L) Walp.) cultivars to induced water stress and phosphorus nutrition
Full text linkThesis (MScAgric) -- University of Stellenbosch, 2003.ENGLISH ABSTRACT: Cowpeas are produced under low and irregular rainfall in most of arid and semi-arid
areas of sub-Saharan Africa. Growth and yield are therefore reduced due to the occurrence
of water stress during the growing season. Knowledge of the responses and adaptive
mechanisms of cowpeas to water stress may help to improve the management practices for
these areas. Therefore, three glasshouse experiments were conducted at Welgevallen
Experimental Farm of the University of Stellenbosch to test the responses of two cowpea
cultivars to water stress. In the first experiment, physiological responses were used to
identify those physiological parameters, which can be used to distinguish between drought
tolerant and susceptible cowpea cultivars. In the second experiment, some of the identified
physiological parameters together with some morphological growth responses, yield and
grain protein content of the same two cowpea cultivars were used to identify which is the
more tolerant cultivar. Tn the third experiment, the hypothesis that increased phosphorus
supply may improve the tolerance of cowpea plants to water stress and their ability of
recover from the stress was tested. The results showed that water stress affected water
relations, morphological growth parameters, yield and grain protein content, but
increasing P supply reduced the effect of water stress and promoted more rapid recovery
after re-watering. Water relations were affected by water stress because it reduced relative
water content, which resulted in reduced water potential and increased leaf diffusive
resistance and proline accumulation. Morphological growth responses and yields were
affected because water stress reduced the leaf area, which resulted in reduced biomass
production and seed yield. Lower leaf area under water stress was the result of the reduced
number of leaves and leaf expansion rate, but the number of leaves was the most
important parameter. Reduced seed yield was due to reduced number of pods. The
responses of the two cultivars tested were different. AB Wit, which performed better
under well-watered conditions was more affected by water stress due to its larger leaf area
that resulted in excessive water loss by transpiration. ACH14 was more drought tolerant
than AB Wit due to a combination of a more rapid stomatal closure and proline
accumulation, which induced osmotic adjustment, and which in tum helped to maintain
higher water potentials. The increased P supply reduced the effect of the water stress.
High-P level plants showed higher root growth, which resulted in more water uptake and
larger leaf area during the water stress period, and after re-watering these plants recovered more rapidly. The more rapid recovery from stress was the result of enhanced root growth
and leaf expansion rate and most probably due to increased water uptake. High-P level
plants also showed more rapid leaf appearance and plant growth at earlier stages compared
to the low-P level plants.AFRIKAANSE OPSOMMING: Akkerbone word onder toestande van lae en wisselvallige reenval in baie ariede en
semi-ariede gebiede van Afrika verbou. In hierdie gebiede word groei en produksie
dikwels beperk deur water tekorte gedurende die groei seisoen. Kennis van reaksies en
aanpassingsmeganismes van akkerbone teenoor water tekorte mag dus help om
produksietegnieke in bogenoemde gebiede te verbeter. Om hierdie rede is drie
glashuiseksperimente onder gekontroleerde toestande op die Welgevallen Proefplaas van
die Universiteit van Stellenbosch uitgevoer. In die eerste eksperiment is fisiologiese
reaksies van twee cultivars gebruik om eienskappe te identifiseer wat gebruik kan word
om tussen droogteweerstandbiedende en droogte gevoelige cultivars te onderskei. In die
tweede eksperiment is sommige van die geidentifiseerde eienskappe asook morfologiese
groei, opbrengs en kwaliteitsreaksies van dieselfde twee cultivars gebruik om die meer
droogte weerstandbiedende cultivar te identifiseer. In die derde eksperiment is die
hipotese dat P-bemesting die droogteweerstandbiedendheid teen en herstelvermoe na
droogte kan verbeter, getoets. Die resultate toon dat water tekorte beide plantwaterverhoudings,
morfologiese eienskappe asook opbrengs en proteieninhoud beinvloed,
maar dat hoe P-peile die invloed van water tekorte verminder en herstelverrnoe na die
droogte verbeter. Plant-waterverhoudings is bemvloed omdat water tekorte relatiewe
waterinhoud van plante verlaag wat aanleiding gee tot verlaagde plantwaterpotensiale,
verhoogde huidmondjie weerstand en 'n toename in prolien inhoud.
Morfologiese eienskappe en opbrengs is benadeel weens 'n veri aging in
blaaroppervlakte wat fotosintetiese vermoe en gevolglik ook biomassaproduksie en saad
opbrengs benadeel. Verlaagde blaaroppervlakte tydens water tekorte was hoofsaaklik die
gevolg van 'n vermindering in aantal blare, terwyl verlaagde saadopbrengs grootliks die
resultaat van 'n vermindering in aantal peule was.
Die cultivar AB Wit wat die hoogste opbrengs onder gunstige groeitoestande gelewer
het, is die meeste bemvloed deur water tekorte omdat die welige blaargroei van hierdie
cultivar, luukse waterverbruik en groter transpirasie verliese veroorsaak het. Die cultivar
ACH 14 daarteenoor het waterverliese beperk deurdat die huidmondjies vinniger gesluit
het en verhoogde prolien-inhoude, osmotiese aanpassings veroorsaak het. Dit het gehelp om waterpotensiale instand te hou. Hierdie cultivar was gevolglik meer droogte
weerstandbiedend as AB Wit.
Hoe vlakke van P-bemesting het die effek van water tekorte verminder weens
verbeterde wortelgroei. Dit het wateropname gedurende en na die peri ode van water
stremming verbeter sodat plante vinniger herstel het na die droe periode. Plante wat by
hoe P-peile gegroei is het ook 'n verhoogde blaarverskyningstempo en 'n toename in groei
tydens die vroee ontwikkelingstadiums getoon.Master
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
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
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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