1,720,955 research outputs found
The effect of dietary calcium and other nutritionally relevant divalent cations on fatty acid-soap formation : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Sciences at Massey University, Manawatū, New Zealand
Get PDFA growing amount of scientific evidence appears to support a relationship between dietary calcium (Ca) and body weight where increased dietary Ca intake leads to weight reduction and the faecal excretion of several fatty acids. One possible mechanism, explaining the effect of dietary Ca on body weight and faecal fatty acid excretion, is the formation of indigestible Ca-fatty acid soaps within the gastrointestinal tract, leading to reduced fat and therefore reduced energy absorption. The objectives of this research were 1) to confirm that dietary Ca reduces fatty acid absorption and that the effect is via the formation of fatty acid soaps, 2) to explore the potential of cations other than Ca to form fatty acid soaps and 3) to investigate where in the gastrointestinal tract Ca-fatty acid soap formation occurs.
In order to investigate the presence of fatty acid-soaps in the gastrointestinal tract, an assay was developed to determine fatty acid-soaps in digesta and faeces. Faecal fatty acid-soap excretion, apparent faecal fatty acid digestibility and apparent faecal Ca digestibility were determined in the growing pig for diets containing different sources of fat (tallow, palmolein oil, olive oil and soya bean oil) and increasing concentrations of Ca (0, 2, 4 and 6 g kg-1 diet). Increasing concentrations of dietary Ca resulted in increased faecal fatty acid excretion (P 80%) for diets containing a fat source rich in saturated fatty acids (tallow and palmolein oil). The fatty acid digestibility of these diets was reduced (P < 0.001) by up to 28% when the dietary Ca intake was increased from 0 g Ca kg-1 diet to 6 g Ca kg-1 diet. Moreover, faecal Ca output of the tallow-based diet, for which the fatty acid soap excretion was the greatest, was statistically higher when compared to the oil containing diets.
These results provide evidence that supports the hypothesis that dietary Ca can impair fat absorption via the formation of indigestible Ca-fatty acid soaps but that the effect is largely limited to fat sources rich in saturated fatty acids as evidenced by the reduction in Ca absorption with tallow.
Given that Ca appears to react with fatty acids to form soaps, it was decided to investigate whether other nutritionally relevant divalent cations (magnesium (Mg), zinc (Zn), iron (Fe) and copper (Cu)) were able to form fatty acid soaps. To that end, in vitro studies revealed that apart from Ca, other divalent cations such as Zn, Mg, Fe and Cu had the ability to form precipitates in the presence of fatty acids. In general, all the divalent cations examined formed precipitates in the presence of at least some of the fatty acids examined, although the extent to which the divalent cation-fatty acid precipitates (soaps) formed varied depending on the cation and fatty acid present. The precipitation of saturated fatty acids (lauric, myristic, palmitic and stearic acid) when incubated with Zn was comparable with that of Ca. However, the precipitation of unsaturated fatty acids (oleic and linoleic acid) with Zn was greater than that observed for Ca. For Fe and Cu, fatty acid precipitation was less than that observed for Ca.
To investigate where in the gastrointestinal tract fatty acid soaps form, growing pigs were fed diets containing either free fatty acids or an intact triacylglyceride (tallow) and calcium carbonate as the Ca source. The amount of insoluble fatty acid-soap present in the gastrointestinal tract was determined at 10 different locations within the tract. The amount of fatty acid-soaps present increased (P < 0.05) at the distal jejunum when the free fatty acid-based diet was fed and at the ileum when pigs received the tallow-based diets, and was correlated with the pH (regardless the diet) of the gastrointestinal tract suggesting that soaps formed as the pH of the gastrointestinal tract increased. Fatty acid-soap formation in the small intestine of pigs receiving the free fatty acids was almost double than for pigs receiving tallow with their diet. There was little soap formation in the hind gut. With the majority of fatty acid soap formation occurring in the distal small intestine (the major absorption site of fatty acids) fatty acid-soap formation has the potential to reduce fatty acid absorption. Feeding a fat-free diet in addition to the two fat containing diets gave insight into mineral absorption in the absence and presence of dietary fat. The apparent digestibility of Ca, Mg, Zn and Fe was lower (P < 0.05) in the presence of dietary fat (free fatty acids or triacylglycerides) suggesting that the formation of divalent cation-fatty acid soaps may have the ability to impair the absorption of divalent cations other than Ca.
In conclusion, high dietary Ca intake leads to increased faecal fatty acid excretion in the form of insoluble fatty acid-soaps. Fatty acid-soap formation can impair the digestibility of Ca and other nutritionally relevant divalent cations such as Zn, Mg and Fe. Moreover, fatty acid-soaps appear to form mainly in the distal small intestine and appear to be associated with gastrointestinal pH. These results contribute to the knowledge of where fatty acid soap formation occurs and provide evidence that fatty acid soap formation can reduce fat absorption and thereby possibly contribute to weight loss
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
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
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
- …
