1,721,146 research outputs found
A Generalization of Rota′s NBC Theorem
No full textAbstractWe generalize Rota′s theorem characterizing the Möbius function of a geometric lattice in terms of subsets of atoms containing no broken circuit and give applications to the weak Bruhat order of a finite Coxeter group and the Tamari lattices. We also give a direct proof of the fact that in the geometric case any total order of the atoms can be used. Simple involutions are used in both proofs. Finally, we show how involutions can be used in similar situations, specifically in a special case of Rota′s Crosscut Theorem as well as in related proofs of Walker on Hall′s Theorem and Reiner on characteristic and Poincaré polynomials
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
Gastrointestinal parasites in snakes: a survey
No full textAim. Anyone who tries to approach the reptile’s parasitology in a scientific perspective, will become immediately aware about the scarcity and fragmentary nature of the available information that in some cases are even misleading (Seghetti M & Traversa D., 2006, Atti III Conv. Naz. SIVSANC, Teramo 5-6 maggio, 39-41). If the attention is focused on the gastrointestinal parasites of snakes, the lack of scientific reports is even more pronounced. Despite their wide distribution in Italy, veterinary expertise in this field is still scarce and incomplete. The laboratory practice, usually reserved to a small group of experts, is not commonly performed. Up to now few attempts there have been made to study the prevalence of different parasites; in many cases the poor information available are not comparable because the survey are performed in different countries, on different species of snakes, with different purposes and using different laboratory techniques. The lack of iconographic support, with the frequent interference due to parasites of preys, does not facilitate the coprological diagnosis, and may lead to false positives (Jacobson E.R., 1983, Current Vet. Therapy, 8:599-606). This work was done on captivity snakes with the aim to identify and to assess the prevalences of their gastrointestinal parasites.
Material and Methods. The survey was carried out from January 2009 to March 2010. A total of 90 snakes breeded, marketed and held as “pets” were screened: 82 from Boidae family and 8 from Colubridae family. All animals were kept under the terms of existing legislation. Individual fresh fecal samples were collected in the context of herpetological fairs, at breeding facilities or at the owners and kept at 4°C until they were processed; 79 (87.7%) animals was born in captivity, the others were captured from various location of the world. The ophids were housed individually at temperature between 28-30°C, in separated plastic or glass boxes and were fed by small live rodents (mouse or rat). The substrate used was mainly paper or paperboard. No snake was treated against endoparasites. The fecal examination was carried out by fecal flotation in saturated sugar-salt solution (specific gravity 1.3). Parasite eggs were identified by their morphology and morphometric characteristics. In order to better understand the results of coprological examinations of snakes, when possible, fecal pools from rats and mouse were collected.
Results. All fecal samples were of normal consistency and color; 49 (54.4%) were seemingly positive, but only 8 animals (1 Boa constrictor constrictor, 1 Boa constrictor imperator, 1 Corallus caninus, 1 Elaphe guttata, 1 Epicrates cenchria cenchria, 2 Morelia viridis, 1 Python regius) were positive for one or more specific parasites of reptiles as strongyles (7,8%), Strongyloides spp. or Rhabdias spp. (3.3%), sarcosporidia (1,1%) and cestodes (1,1%). The higher prevalences, 18,2% (2/11) were found in wild-caught snakes group; in born captive group prevalences were 6,8% (5/73). In 46 (51%) samples pseudoparasites were found: rodent’s mites eggs 36 (40%), rodent’s pinworms 22 (24,4%) and rodent’s cestodes 11 (12,2%). Prevalence of coccidia was 26,7%. Coprological examination of rodents’ fecal pools has highlighted the same eggs/oocists found in linked snakes, supporting the diagnosis of pseudoparasitism.
Conclusions. This preliminary work confirm the frequent presence of pseudoparasites in captivity snake, with low prevalence of specific parasites. Gastrointestinal parasites are not a serious problem for these animals, considering that pathogens able to survive and replicate, indoors and under controlled conditions, without an intermediate host, are very few (Radhakrishnan S.P. et al, 2009, Zoo Biology, 28:253-258). In wild-caught snake, parasite prevalence can be high and specific parasite, in stressfull conditions as captivity, can become a serious problem, compromising the reptile’s welfare (Kiel J.L., 19..
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
La regola del corpo o il corpo della regola: la donna musulmana nella lente dei media
No full textIl nostro obiettivo è stato di esplorare le aree semantiche attorno cui ruota il discorso della donna musulmana nei media, ovvero come le donne musulmane vengono rappresentate dai media occidentali e quali differenze emergono mettendo a confronto la stampa italiana ed anglosassone.
I quotidiani selezionati per la nostra ricerca sono il The Guardian per il Regno Unito e il Corriere della Sera per l’Italia, scelti per aver la più alta tiratura e diffusione nel proprio Paese ed essere simili nelle loro caratteristiche. La ricerca è stata svolta attraverso un’ analisi specifica dei testi raccolti attraverso l’utilizzo del software di analisi T-LAB (Lancia, 2004) per esaminarne le specifiche caratteristiche quali- quantitative
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
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