1,720,957 research outputs found
Effect of extraction solvents and encapsulation on the efficacy of certain medicinal plant extracts to inhibit enteric methane emission
Full text linkThesis (PhD)--University of Pretoria, 2023A series of in vitro and in vivo experiments were conducted to evaluate the antimethanogenic properties of four medicinal plants (Aloe vera, Jatropha curcas, Moringa oleifera, and Piper betle) extracts as alternative rumen modifiers to antibiotics to modulate rumen fermentation and inhibit methane production. In the first study, two solvents (methanol and water) were used in three different combinations (70, 85, and 100%) to extract bioactive compounds from the four studied medicinal plants as some of their metabolites have been reported to possess rumen modulation properties and improve nutrient utilization in ruminants, thereby reducing enteric methane emission per unit of animal product. The extracts were evaluated at 50 mg kg-1 DM feed as an additive to Eragrostis curvula hay substrate in vitro. Results showed an increase in extract yields with increasing water content in the extraction solvents. The effect of extraction solvents was also observed in the concentration of the bioactive compounds in each plant extract when analysed with UPLC-MS, these plant bioactive compounds showed different solubility values. Subsequently, promising plant extracts were selected based on yield and methane inhibition potentials for subsequent encapsulation with alginate as wall material. The encapsulated products were scanned using electron microscope for morphological characterisation and later their methane inhibition attributes were investigated using both in vitro and in vivo studies. The particle characterization of the encapsulated extracts was carried out using a scanning electron microscope (SEM) and images were generated for a morphological study. Gas measurements were taken at regular intervals of 3, 6, 12, 24, and 48 h during the incubation period. Methane emission was determined for each gas sample with the use of gas chromatography. During the first phase of the in vitro study, the plant extract treatments were incubated with feed samples to test their methane inhibition potentials, their effect on total gas production (TGP), and their organic matter digestibility (IVOMD). In the second phase of the in vitro study, Aloe vera and Moringa oleifera extracts were encapsulated with alginate and/or alginate-chitosan wall materials and the final product is incubated with feed samples to evaluate their methane inhibition potentials, their effect on TGP, and IVOMD. The results from the first in vitro study indicated that the four plant extracts from three aqueous-methanol extractions (70%, 85%, and 100%) generally reduced methane emission in different proportions at 50 mg kg-1 DM without adversely affecting TGP and IVOMD of E. curvula hay. However, the methane inhibition potentials of the tested plant extracts were not influenced by the extraction solvents. For the second in vitro study, alginate encapsulated and alginate-chitosan encapsulated plant extracts were also tested together with non-encapsulated plant extracts on E. curvula hay and also reduced methane production. Higher methane inhibitions were noted for the alginate encapsulated and alginate-chitosan encapsulated extracts as against the non-encapsulated extracts, without negatively affecting the TGP and IVOMD.
Finally, encapsulated M. oleifera plant extract was selected for in vivo evaluation to determine its effect on enteric methane production, rumen fermentation parameters, growth performance, feed intake, apparent digestibility, and nutrient utilization of South African Mutton Merino (SAMM) lamb. A total of thirty (30) SAMM lambs were first ranked according to their body weight and divided into three groups with approximately equal body weight measurements. The three treatment groups were randomly allotted to one of the three treatments (two plant extract treatments and control). The plant extract treatments included non-encapsulated M. oleifera extract (NME) and encapsulated M. oleifera extract (EME) additives. These additives were provided to the lambs at 50 mg kg-1 feed DM intake by incorporating them into a ball-like molasses mix and presented at 7:30 am daily to the experimental lambs. All treatments were placed on the same total mixed ration formulated with a 42% roughage component. The growth performance study lasted for 14 weeks, including adaptation, and the feed digestibility study lasted for 14 days. The lambs were moved into the open circuit respiratory chambers for methane emission measurements in six batches. The methane emission measurements and digestibility study were done concurrently with the growth performance study. For the in vivo study, both the NME and EME reduced (p < 0.05) enteric methane emission by approximately 22.61% and 20.06%, respectively; reduced rumen ammonia nitrogen (NH3-N), urinary nitrogen excretion and feed conversion ratio but increased nitrogen retained as a percentage of intake without adverse effect on nutrient intake, apparent digestibility, and performance of SAMM lambs. Supplementation of SAMM lambs with NME and EME as dietary additives did not affect the rumen fermentation parameters. The alginate encapsulation of MO plant extract is safe and did not reduce the efficacy of MO plant extracts compared to non-encapsulated plant extracts, and is therefore recommended for practical use as antimethanogenic dietary additives in the feeding system of ruminant animals. Further study needs to be conducted to determine the effect of alginate encapsulated MO plant extracts on the rumen microbial populations and meat quality of the lambs. Also, other wall materials that can act as good carriers of active compounds in rumen medium should be evaluated for methane inhibition in livestock production.Animal and Wildlife SciencesPhDUnrestricte
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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