1,720,967 research outputs found
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
Metal chelates of 2-hydroxy-4-methylthiobutanoic acid in animal feeding: preliminary investigations on stability and bioavailability
No full textVariations 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
Metal Chelates of 2-hydroxy-4-methylbutanoic acid in animal feeding. Part 2: further characterization, in vitro and in vivo investigations
No full textThe a-hydroxyacid 2-hydroxy-4-methylthiobutanoic acid (the so-called methionine hydroxy-analogue, MHA), largely used in animal
nutrition as a source of methionine, forms stable metal chelates with divalent metals of formula [{CH3SCH2 CH2CH(OH)-
COO}2M] Æ nH2O. Protonation and iron(III) and copper(II) complex formation constants have been determined by
potentiometry at 25 C. Distribution diagrams show that no free Fe3+ cations are present in solution at pH > 2.5. ESI-MS (Electron-
Spray Ionization Mass Spectrometry) investigations carried out both on iron and zinc complexes in solution have evidenced
various species with different MHA/metal ratios. In vivo trials were carried out with rats. After receiving a zinc-deficient diet for
3 weeks, animals were fed the same diet added with zinc sulfate or zinc/MHA chelate; the zinc content of faeces was higher
(+45%; P < 0.05) in sulfate fed rats, whereas zinc retention was higher (+61%; P < 0.05) in the Zn/MHA diet. Experiments in vitro
with human intestinal Caco-2 cells indicated that the MHA/Fe chelate was taken up by the cells without any apparent toxic effect.
The iron uptake was higher than that of iron nitrilotriacetate (Fe3+NTA), an effective chelate for delivering iron to milk diets. In
conclusion, these data indicate that the use of MHA chelates could be a valuable tool to increase bioavailability of trace minerals
and reduce the environmental impact of animal manure
Metal chelates of 2-hydroxy-4-methylthiobutanoic acid in animal feeding: characterization, in vitro and in vivo investigations.
No full textMetal chelates of 2-hydroxy-4-methylthiobutanoic acid in animal feeding: characterization, in vitro and in vivo investigations
Giacomo Biagi,a Enrico Cinti,b Simonetta Ferruzza,c Attilio L. Mordenti,a Giovanni Predieri,d Matteo Tegonid
aDIMORFIPA, University of Bologna, Via Tolara di Sopra 50, Ozzano Emilia, Italy; bAgristudio S.r.l., Via Gramsci 56, Reggio Emilia, Italy; cINRAN, Nutrition National Institute, Via Ardeatina 546, Roma; aGIAF Chemistry Department, University of Parma, Parco delle Scienze, Parma, Italy
Interest in using alternative mineral sources, particularly those chelated with proteins or aminoacids, has recently increased due to their reported higher availability compared to conventional (inorganic) sources [1]. For example, it has been found that ruminants respond (increased growth, milk production etc.) to certain trace mineral complexes or chelates [2] and that aminoacid chelates show a higher availability than the inorganic compounds when fed to rainbow trouts, even in presence of phosphates and phytates [3]. However, there are still contentions both regarding improved bio-availability and integrity of metal chelates at the low pH of the first digestive tract. This important drawback can be overcome by using a chelating ligand able to improve the stability of chelates at low pH values. Preliminary results of our investigations [4] indicate that 2-hydroxy-4-methylthiobutanoic acid (MHA; the so-called methionine hydroxy-analogue), an alpha-hydroxyacid largely used in animal nutrition as a source of methionine has the requested features. It forms bis-chelate complexes of formula [{CH3SCH2CH2CH(OH)COO}2M].nH2O (M = Ca2+, Mg2+, Mn2+, Fe2+, Co2+, Cu2+ or Zn2+). Potentiometric investigations for the copper(II), zinc(II) and iron(III) MHA chelates in solution show that these species, differently from AA chelates, are rather stable even at low pH values. In the case of iron, the distribution diagram of the system Fe3+/MHA does not show any trace of free iron cations at pH > 2.5. Furthermore, in order to gain insight about biavailability of MHA chelates, in vitro and in vivo investigations were performed. In the in vitro studies, human intestinal Caco-2 cells were exposed to Fe3+/MHA chelate solutions. The iron/MHA chelate did not alter the permeability of Caco-2 tight junctions and was taken up to a larger extent than the reference iron chelated with nitrilotriacetic acid. In vivo investigations were carried out in the rat. After receiving a zinc-deficient diet for 3 weeks, animals were fed the same diet added with zinc sulfate or zinc/MHA chelate; the zinc content of faeces was higher (+ 45%; P < 0.05) in sulfate fed rats, whereas zinc retention was higher (+ 61%; P < 0.05) in the Zn/MHA diet.
References
[1] Ashmead, H.D., 1992, The Roles of AA Chelates in Animal Nutrition, Moyes Publ., Park Ridge, NJ. [2] Spears, J.W., 1996, Anim. Feed Sci. Technol., 58, 151-163. [3] Satoh, S. et al., 2003, Aquacult., 225, 431-444. [4] Predieri, G. et al., 2003, J. Inorg. Biochem., 95, 221-224
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
- …
