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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
Marine gastrotrichs from Lanzarote, with a description of a phylogenetically relevant species of Urodasys (Gastrotricha, Macrodasyida)
No full textSampling campaign took place in October 2011 and included 7 locations and 16 stations along the eastern coast of the island of Lanzarote (Spain). Samples yielded 61 species for a total of 96 records. Thirty-six species (27 genera and 11 families) belong to Macrodasyida while 25 species (18 genera, 7 families) to Chaetonotida. Thirty-two are known species while 29 appear to be undescribed taxa or putatively so. The finding at Lanzarote of some of the known species bear particular significance: Oregodasys cirratus and Tetranchyroderma canariense are recorded for the second time ever, while Musellifer delamarei and Urodasys acanthostylis were previously known only from the Mediterranean, and Urodadys mirabilis was acknowledge only for northern Europe. Furthermore, the presence in the island of Chaetonotus apechochaetus, C. apolemmus, C. siciliensis, Heterolepidoderma loricatum, Lepidodasys unicarenatus, Musellifer delamarei, Thaumastoderma mediterraneum, and Urodasys acanthostylis, strongly suggest them to be part of the temperate/warm fauna that invaded the Mediterranean basin after the Missinian crisis during the different climate eras. Of the new species, one is described as its characteristics widen substantially our knowledge on the entire genus. Urodasys completus sp. nov. is unique in that it possesses, among others, two testes and a sclerotic stylet. Results of a phylogenetic analysis indicated that the sequence of the evolutionary transformation that have occurred in the reproductive system of the species of Urodasys are likely dissimilar from the ones proposed thus far. The overall results testify the need to continue the exploration in the Canary Islands
Effect of the size of polycyclic aryl groups on the competition between adiabatic/diabatic photoisomerization mechanisms of: Cis -styrylarenes
No full textThe occurrence of adiabatic photoisomerization in the singlet manifold directly from 1Z∗ to 1E∗ has been found to be more common than expected. This mechanism has been experimentally evidenced through a detailed fluorimetric study for a large series of styrylarenes. Its weight on the overall cis-trans photoisomerization has been determined and found to increase when increasing the size of the polycyclic chromophore
Novelties in the Evolution of the Urodasys reproductive system (Gastrotricha, Macrodasyida)
No full textMacrodasyidan gastrotrichs are hermaphrodites with complex accessory reproductive organs that function in sperm transfer and receipt. Unfortunately, homology among the organs of members of different clades is largely undetermined, troubling a clear understanding of the evolutionary trends in the reproductive biology of these animals. The present study investigates the evolution of reproduction in species of the peculiar genus Urodasys, quite popular among researchers working on meiofauna in virtue of their very long tail. These gastrotrichs are extremely interesting also because they show a wide range of structures, modes, and reproductive strategies. It is likely that a phylogenetic study of these taxa may shed light on the evolutionary trends in the reproductive biology of the genus and possibly of the entire phylum. Urodasys presently consists of 15 species, one of which, U. viviparus, is parthenogenetic and ovoviviparous, while the others are hermaphroditic and oviparous. Four of the latter species show paired ovaries and testes, but no accessory sexual organ, whilst 10 possess two ovaries, a single testis and a sclerotic, copulatory organ called a stylet. Recently, a new species bearing a stylet but two testes was found at Lanzarote (Canary Islands). All this data was opportunely coded and cladistically analyzed. Meanwhile, phylogenetic analyses based on sequences of the 18S rDNA gene obtained from representative species were concurrently carried out. The results of the two analyses are widely overlapping and substantially separate the investigated species into two clades, with the new species that appears as an early divergent line along the evolutionary branch of the stylet-bearing taxa. However, U. viviparus appears to be allied with the stylus-lacking species in the morphological analyses, while the molecular analyses place it amongst the stylet-bearing species. In any case, regardless of the position of U. viviparus, the results indicate that the sequence of evolutionary transformations occurred in the reproductive system of the species of Urodasys is likely dissimilar from those previously proposed by other authors
Gaining and losing on the way: the evolutionary scenario of reproductive diversification in genus Urodasys (Macrodasyida: Gastrotricha) inferred by multi-gene phylogeny
No full textThe microscopic members of the genus Urodasys are easily recognizable due to their exceptionally long tail. There are 17 described species within
this iconic genus, each distinguished by various sexual organ arrangements and reproduction modalities, including the sole known ovoviviparous
gastrotrich species. The remarkable variety in reproductive characteristics has captured the interest of researchers aiming to illuminate its origin
and evolution. The recent discovery of a species bearing a novel set of reproductive structures has challenged early hypotheses. However, all the
evolutionary scenarios put forward need to be more convincing. To gain deeper insight into the evolutionary history of these iconic animals, we
obtained the nucleotide sequence of two nuclear genes and one mitochondrial gene from species’ representatives of the four known possible
combinations of the reproductive apparatus and reproduction modalities. The multi-gene data matrix was analysed phylogenetically using three
approaches. The analyses yielded phylogenetic trees with invariant topology. In all cases, the specimens appear organized in four robustly supported
clades and subclades that reflect their reproductive system organization. Our results suggest that the sclerotized stylet evolved inside the
copulatory organ before the loss of the left testis and offers a new scenario for the evolutionary history of genus Urodasys
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
A contribution to the taxonomy and phylogeny of the genus Chaetonotus (Gastrotricha, Paucitubulatina, Chaetonotidae), with the description of a new species from Italian inland waters
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