1,721,423 research outputs found
Urban biodiversity and design
No full textURBAN BIODIVERSITY AND DESIGN
Urban biodiversity and design / Müller, Norbert [Hrsg.] (Rights reserved) (-
Antigenic variation and the murine immune response to Giardia lamblia.
No full textThe protozoan parasite Giardia lamblia is an important causative agent of acute or chronic diarrhoea in humans and various animals. During infection, the parasite survives the host's reactions by undergoing continuous antigenic variation of its major surface antigen, named VSP (variant surface protein). The VSPs form a unique family of cysteine-rich proteins that are extremely heterogeneous in size. The relevance of antigenic variation for the survival in the host has been most successfully studied by performing experimental infections in a combined mother/offspring mouse system and by using the G. lamblia clone GS/M-83-H7 (human isolate) as model parasite. In-vivo antigenic variation of G. lamblia clone GS/M-83-H7 is characterised by a diversification of the intestinal parasite population into a complex mixture of different variant antigen types. It could be shown that maternally transferred lactogenic anti-VSP IgA antibodies exhibit cytotoxic activity on the Giardia variant-specific trophozoites in suckling mice, and thus express a modulatory function on the proliferative parasite population characteristics. Complementarily, in-vitro as well as in-vivo experiments in adult animals indicated that non-immunological factors such as intestinal proteases may interfere into the process of antigen variation in that they favour proliferation of those variant antigen-type populations which resist the hostile physiological conditions within the intestine. These observations suggest that an interplay between immunological and physiological factors, rather than one of these two factor alone, modulates antigenic diversification of a G. lamblia population within an experimental murine host and thus influences the survival rate and strategy of the parasite
Proisocrinins A-F, brominated anthraquinone pigments from the stalked crinoid Proisocrinus ruberrimus
No full textNew brominated anthraquinone pigments, proisocrinins A-F (1-6), were isolated from the strikingly scarlet-colored stalked crinoid Proisocrinus ruberrimus, which had been collected in the deep sea of the Okinawa Trough, Japan. The structures of the compounds were elucidated by spectroscopic analysis including HRMS, 1D 1H and 13C NMR, and 2D NMR. CD spectroscopy revealed that all compounds are present as optically active enantiomers. This is the first report of tribromo and tetrabromo anthraquinones from a natural source
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
Tritrichomonas--systematics of an enigmatic genus.
No full textTritrichomonas spp. are parasitic protozoans that proliferate on mucus membranes of the urogenital, gastro-intestinal or nasal tract. For instance, Tritrichomonas foetus is an important cause of reproductive failure in cattle. Some years ago, T. foetus was also identified as a causative agent of diarrhoea in cats. Previous studies on the morphological, physiological and molecular levels have raised doubts as to the phylogenetic relationship among some Tritrichomonas species, particularly in relation to T. foetus, Tritrichomonas suis, and Tritrichomonas mobilensis. With the advent of molecular genetic tools, it has become clear that these three tritrichomonad species are closely related or may even represent the same species. Indeed, since recently, T. suis and T. foetus are generally considered as one species, with T. mobilensis being a closely related sister taxon. To date, molecular studies have not yet been able to resolve the taxonomic (specific) status of T. foetus from cattle and cats. In the future, novel genomic approaches, particularly those involving next generation sequencing are poised to resolve the taxonomy of Tritrichomonas spp. Here, we review the literature on the current state of knowledge of the taxonomy of T. foetus, T. suis, and T. mobilensis with special reference to the relationship between T. foetus from cattle and cats
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
- …
