1,720,955 research outputs found
The biology of the cosmopolitan fish parasite Neobenedenia girellae
Full text linkMonogeneans are a fascinating parasite group to study. They can be harmful pathogens of finfish and display interesting relationships with their hosts making research on these species engaging from both ecological and economic perspectives. Neobenedenia (Family Capsalidae) Yamaguti, 1963, is a notable monogenean genus and is notorious for the large number of potential host species that the constituent parasite taxa are able to infect. The distinct lack of research on Neobenedenia biology and the diversity of species present in Australian waters presented me with an opportunity to conduct a series of research studies designed to improve understanding of this parasite genus. The aim of this thesis was to provide an in-depth investigation of Neobenedenia phylogenetics and detailed biology (including the growth, morphology, reproduction, and biochemistry) of the species in Australia.
The first data chapter (Chapter 2) determined the phylogenetic relationships between 33 Neobenedenia isolates by amplifying three genes; two nuclear (H3 and 28S rDNA) and one mitochondrial (cytochrome b). Isolates were collected from a total of 23 host species and nine countries in both hemispheres and included 16 isolates from 12 host fishes in Australia. Representative samples for Neobenedenia melleni MacCallum, 1927, Neobenedenia pacifica Bravo-Hollis, 1971, and Neobenedenia longiprostata Bravo-Hollis, 1971, formed discrete clades and collectively accounted for seven of the 33 samples used in this study. The remaining 26 isolates formed a single clade genetically distinct from all representative specimens. Morphological observation of these 26 isolates confirmed that they were morphologically indistinguishable from N. melleni despite displaying clear genetic differences in the phylogenetic trees. This confirmed the suggestion by the scientific community that Neobenedenia girellae Hargis, 1955, a species that was synonymised with N. melleni in 1996, should be reinstated as its own taxon, a recommendation that is encouraged by the authors.
The second data chapter (Chapter 3) focussed on the effect that a number of environmental variables had on the morphology of N. girellae. Neobenedenia girellae is extremely flexible in the morphology it exhibits. Temperature was identified as the strongest factor affecting the morphology of this species, however, there was an indication that morphology may also be dictated by the host species that the parasite attaches to. Between different host species, parasites exhibited changes in the morphology of the attachment organs which come in direct contact with their host's surface. This is proposed to be a function of maximising the ability of their attachment organs to the scale/mucus interface of heterogeneous host surfaces. The morphology of parasites attached to the same host species at different temperatures differed most in their total body size. Features associated with the attachment of the parasite to the host did not differ which is likely a product of the homogenous host surface available to the parasite. The variation observed in this species explains why N. melleni and N. girellae have been misidentified, fuelling considerable taxonomic confusion in Neobenedenia in the past.
The third data chapter (Chapter 4) focussed on elucidating reproductive and life cycle biology of N. girellae in temperatures and salinities typical of tropical regions. Neobenedenia girellae completed its life cycle almost twice as fast in warm, high saline conditions compared to cooler temperatures. Hatching and infection success and oncomiracidia longevity was significantly reduced in salinities less than 22 ‰ compared to higher saline conditions (35 and 40 ‰). A total of two strategically timed treatments on stock was recommended in cool to moderate temperatures in salinities of seawater or higher. In warmer conditions (> 30 ºC), a third treatment of stock is required as parasites reach sexual maturity faster than the time taken for all eggs to hatch in a given period. The development of an accessible and user-friendly strategic treatment timetable informs fish farmers and aquarists alike when to treat their fish to maximise the efficacy of treatments and minimise labour costs and reinfection.
The fourth data chapter investigated the feasibility of collecting sufficient quantities of N. girellae eggs for biochemical analysis (Chapter 5). An established laboratory culture of N. girellae was optimised to enable the production of larger quantities of eggs over short periods of time for collection and subsequent biochemical analysis. Eggs were found to be composed primarily of water (79.12 %) followed by protein (11.51 %) and lipid (2.50 %). Lipids were composed of approximately equal amounts of saturated, monounsaturated, and polyunsaturated fatty acids (35.43 ± 0.38 %, 29.08 ± 0.38 %, and 35.50 ± 0.53 %, respectively). The predominant lipid classes were phosphatidylcholine (21.90 ± 1.42 %) and triacylglycerols (TAG) (33.82 ± 1.20 %). This is the first study to quantify the biochemical components of marine monogenean eggs but only provided insight into the biochemical contents of N. girellae eggs after they had been laid and not throughout development.
Chapter 6 expanded on the topics identified in Chapter 5 and quantified the biochemical contents of eggs throughout embryogenic development and across a range of temperatures. This provided valuable information on metabolic fuels employed by embryos as they developed and in different environments. Additionally, reproductive biology (fecundity, egg-laying period, and egg volume) was investigated to provide a complete picture of N. girellae reproductive investment. Adult parasites were significantly larger at cooler temperatures and produced significantly larger eggs towards the end of their reproductive lives. Fecundity of adults was highest at 20 and 30 ºC compared to 25 ºC. The biochemistry of freshly laid eggs was similar to the results observed in Chapter 5. Proximate composition of eggs did not significantly change over the three temperatures tested, however, warmer temperatures resulted in the significant decrease in a number of mono- and polyunsaturated fatty acids throughout embryogenesis. The most prolific lipid classes were phospholipids and TAGs. The most notable change from the biochemical profile observed in Chapter 5 was that the amount of acetone mobile polar lipids in eggs more than doubled in the present study to compose up to 25% of the lipids in N. girellae eggs.
Neobenedenia girellae is a parasite with a turbulent taxonomic history. Now that appropriate genes have been recognised that can accurately identify this species, potentially misidentified samples from previous studies can be clarified and the geographic and host records can be built on a solid foundation. This allows for future research to confidently credit any biological research to this taxon which has important implications for modelling populations on hosts, epidemiology, and management of this species on dozens of host taxa. If, as predicted, parasites and pathogens become a more immediate problem for global food security in a rapidly changing climate, accurately defining and identifying threats and developing methods for management and eradication of these species is paramount. This thesis presents a comprehensive assessment of one of the most cosmopolitan monogenean species in the world and the intimate knowledge generated on its biology can be used to reduce the impact of outbreaks on food fish production
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
- …
