1,721,413 research outputs found
Clinical microbiologist; the gatekeeper of informative diagnostics
Full text linkKluytmans, J.A.J.W. [Promotor]Koopmans, M. [Promotor]Rossen, J.W.A. [Copromotor]Peeters, M.F. [Copromotor
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
Growth and metabolism of sponges
No full textSponges (phylum Porifera) are multi cellular filter-feeding invertebrate animals living attached to a substratum in mostly marine but also in freshwater habitats. The interest in sponges has increased rapidly since the discovery of potential new pharmaceutical compounds produced by many sponges. An enormous amount of different chemical structures have been found. Thus far no sustainable production technique has been developed for these marine natural products, because not sufficient knowledge is present about the needs of sponges for both growth and bioactive compound production. The aim of this thesis was to get a better understanding of the growth and metabolism of sponges and of their nutritional needs. Aquaculture is thus far the best method to produce these compounds, although also this technique is not fully developed. To gain more insight in the nutritional needs for growth, we studied the growth rate of Haliclona oculata in its natural environment, Oosterschelde, the Netherlands, and monitored environmental parameters in parallel (Chapter 2). A stereo photogrammetry approach was used for measuring growth rates. Stereo pictures were taken and used to measure volumetric changes monthly during 1 year. The volumetric growth rate of Haliclona oculata showed a seasonal trend with the highest average specific growth rate measured in May: 0.012±0.004 day−1. In our study a strong positive correlation (p In order to produce drugs by culturing sponges their growth must be improved. To improve growth, basic knowledge about how food sources are used by the sponge is needed. To find the exact relation between food retained and food converted to sponge biomass we need to be able to distinguish between feed components and sponge biomass, which means we need biomarkers for the feed and for the sponge. The fatty acid (FA) composition of organisms is specific and can therefore be used as biomarkers. We identified and compared fatty acid profiles of five different sponges in three habitats with those in the suspended particulate matter (SPM) in the surrounding water (Chapter 4). Haliclona oculata and Haliclona xena from the Oosterschelde, Haliclona xena and Halichondria panicea from Lake Veere, both in The Netherlands and Dysidea avara and Aplysina aerophoba from the Mediterranean were studied. In the SPM we found comparable FAs to the FAs of sponges up to chain lengths of 28 C-atoms. Different species of sponges showed similarities, but also very different FA profiles, while they were collected from the same habitat at the same moment. The biomarkers for diatoms and dinoflagellates were abundantly found in all sponges except A. aerophoba as this sponge relies mostly on bacterial food sources based on the many bacterial FAs found in this sponge. In all species, except A. aerophoba, C26:3(5,9,19) and C26:2(5,9) were very abundantly present. These FAs were also abundant in the SPM, while it was stated in literature that these compounds are very typical for sponges. Several FA biomarkers were found for the different sponges. Fatty acid composition is dependent on different factors like food availability and temperature and thus the composition will change in the different seasons. We have studied fatty acid composition and stable isotope 13C natural abundance of suspended particulate matter (SPM) from seawater and sponges in different seasons in the same locations as in chapter 4 (Chapter 5). 13C natural abundance can be used to find the origin of compounds, as the 13C values of compounds are similar to the values from their original producers. The FA concentration variation in sponges was related to changes in fatty acid concentration in SPM. 13C natural abundance in sponge specific FAs showed very limited seasonal variation at all sites. Algal FAs in sponges were mainly acquired from the SPM through active filtration in all seasons. Sponge specific FAs had similar 13C ratios as algal FAs in May at the two Dutch sites, suggesting that sponges were mainly growing during spring and probably summer. During autumn and winter, they were still actively filtering, but the food collected during this period had little effect on sponge 13C values suggesting limited growth. The bacterial sponge A. aerophoba relies mostly on the symbiotic bacteria. In all sponges we found that the ω7 longer chain FAs, C24:1(17) and C26:3(5,9,19) could be traced back to be of bacterial origin. Using a 13C pulse-chase approach metabolic rate can be studied inside organisms. The carbon metabolism of two marine sponges, Haliclona oculata from the Oosterschelde (The Netherlands) and Dysidea avara from the Mediterranean (Spain), has been studied (Chapter 6). The sponges were fed 13C labelled diatom (Skeletonema costatum) for 8 hours in a closed system during which they took up between 75 and 85 % of the diatoms added. At different times whole sponges were sampled for total 13C enrichment, fatty acid composition and 13C enrichment in these fatty acids. During the first day the level of 13C label inside the sponges stayed the same after which the 13C label was metabolized and excreted. Algal biomarkers present in the sponges were highly labeled after feeding and their labeling levels decreased from the second day until no label was left 10 days after enrichment. The sponge specific long chain C26 fatty acids incorporated 13C label already during the first day and the amount of 13C label inside these FAs kept increasing until 3 weeks after labeling. Thus, the algae fed to the sponges were taken up by the sponges within 8 hrs and first conversion started during the first day. Conversion of label occurred at least until at least 3 weeks after feeding. In different studies it was shown that sponges grow slow, but are able to regenerate damaged tissue fast. Moreover, it has been found that damaged tissue coincides with higher secondary metabolite production. Therefore, we were interested in carbon metabolic rate changes after damaging sponge tissue. We have examined the change of carbon metabolic rate of fatty acid synthesis due to mechanical damage of sponge tissue in Haliclona oculata and Dysidea avara (Chapter 7). Metabolic studies were performed by feeding sponges with 13C labeled biomass of diatom, Pheaodactylum tricornutum, either after or before damaging and tracing back the 13C content in the damaged and healthy tissue. Filtration and respiration rate in both sponges responded quickly to damage. For the finger-sponge H. oculata the rate of respiration was reduced immediately after damage. 6 Hours after damage the filtration rate increased to a level that was higher than the starting value, while the respiration rate returned to the initial value before damage. For the encrusting sponge D. avara the filtration rate also decreased directly after damage, but in this case it did not return to the value before damage after one day. Respiration was not measured for D. avara. The 13C data revealed that H. oculata has a higher metabolic rate in the tips where growth occurs compared to the rest of the tissue and that the metabolic rate is increased after damage of the tissue. For D. avara no differences were found between damaged and non damaged tissue. Thus far it is still not fully understood why, when, where and how bioactive metabolites are produced in sponges. For the near future sea-based sponge culture seems to be the best production method. However, for controlled production in a defined system it is better to develop in vitro production methods. This could be in vitro sponge culture or sponge cell culture, culture methods for symbionts or transfer production routes into another host. We still have insufficient information about the background of metabolite production in sponges. Before culture methods are developed we should focus on factors that induce metabolite production, which could be done in the natural habitat by studying the relation between stress factors (such as predation) and the production of bioactive metabolites. Next, the biosynthetic pathway of metabolite production should be unraveled, as well as the genes involved. The location of production within the sponge should be identified in order to choose between sponge cell culture and symbiont culture. Alternatively the biosynthetic pathways could be introduced into hosts that can be easily cultured in bioreactors. Chapter 8 discusses the current state of sponge metabolite production and the steps that need to be taken to develop commercial production techniques. The different possible production techniques are also discussed. <br/
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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