1,720,953 research outputs found
Aspects of Biology of the Weed of Arable Crops broom corn millet (Panicum miliaceum L.)
No full textGrass weeds such as Panicum miliaceum L. (broom corn millet) are a persistent problem for agriculture, causing significant crop losses. A weedy biotype of broom corn millet is already a troublesome weed on North American arable farms, and has recently emerged as a threat to New Zealand corn and maize crops. This thesis describes aspects of the biology of broom corn millet under New Zealand conditions. Experiments were designed to understand under what conditions broom corn millet is mostly likely to affect crop growth.
Experiments were conducted in a glass house and a laboratory to observe the effect of temperature on germination and early growth of broom corn millet. The pot-based glasshouse experiment compared germination and growth between a range of controlled substrate temperatures. The response of broom corn millet to temperature was typical of that expected for a C₄ plant. At 10°C seeds germinated later and in lower proportions compared to 15°C, 20°C and 25°C. Growth and above ground dry biomass accumulation also increased with increasing substrate temperature, with the highest dry biomass accumulated at 25°C, primarily because of increases in germination rate. In a laboratory experiment conducted at temperatures ranging from 5°C and 34°C, temperatures greater than or equal to 20°C were more favourable for germination of broom corn millet seeds. The optimum temperatures for germination were 27°C to 34°C. The threshold germination temperature for the seed lot used was 7.4°C.
Broom corn millet seeds were tested for their ability to germinate and emerge from a range of planting depths when planted in pots containing 16 soil types from around New Zealand. Seedlings emerged from 120 mm depth in all soil types. In six soil types seeds of broom corn millet were able to emerge from the greatest depth tested of 170 mm, very deep compared to most herbaceous weeds. In general, seedling emergence reduced with increasing depth, whereas suicidal germination increased. Step-wise binomial regression of emergence against various soil physical properties did not reveal any significant relationship between soil physical properties and seedling emergence.
To observe the affect of competition on both the weed (broom corn millet) and the crop (sweet corn), plants of both species were grown together in pots at a range of planting ratios. Plants were also grown in monoculture to observe growth without competition. In the competition trial broom corn millet emerged after sweet corn and affected sweet corn above ground biomass during the first four weeks. However, this effect did not persist as sweet corn biomass increased irrespective of the level of competition from broom corn millet plants. The monoculture experiment indicated that sweet corn grew better without competition whereas growth of broom corn millet was stimulated while growing in competition. The poor competition by broom corn millet plants was assumed to be the result of unseasonal low temperatures during the period immediately after sewing and demonstrated that broom corn millet plants emerging after the crop may not affect crop growth.
The likely persistence of New Zealand broom corn millet seeds in soil is unknown. A laboratory based Controlled Ageing Test (CAT) was therefore evaluated for its ability to predict the persistence of seeds. The test was conducted using seeds of nodding thistle (Carduus nutans), for which real time persistence data is available. In two additional experiments, the CAT was used to estimate the potential persistence of New Zealand sourced broom corn millet seeds. The CAT derived half life time (P₅₀) of nodding thistle seeds did not compare well with the field derived P₅₀ for nodding thistle seeds, with the CAT results suggesting less persistence compared to actual persistence. Examination of the CAT results for broom corn millet showed a decline in seed viability from 30 to 50 days, followed by a sharp decline at 75 days. The midpoint of the initial decline (40 days) was taken as the P50 for broom corn millet. This value is similar to existing information for broom corn millet in North America, and indicates that broom corn millet will form a moderately persistent seed bank in New Zealand.
In conclusion, results suggest that higher temperatures favour the growth of broom corn millet. Planting of crops earlier in the season may reduce competition by this weed. However, increasing temperatures as a result of global climate change will enhance conditions for broom corn millet and may increase future crop losses caused by this weed. The ability of broom corn millet’s relatively large seeds to germinate and emerge from depth will limit the efficiency of conventional weed control practices, such as ploughing and stale seed beds. The ability to form a moderately persistent seed bank suggests that once introduced, broom corn millet will be challenging to eradicate because of its prolific seed production. Significant changes in weed control practices will therefore be required to manage broom corn millet in the future
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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