1,720,964 research outputs found
Two similar new species of Alvania Risso,1826(Caenogastropoda: Rissoidae)from the late Cenozoic of Italy
No full textTaxonomy and palaeobiogeography of the Cenozoic Euro-Mediterranean rissoid gastropod Galeodinopsis and its relationship with close genera
Full text linkThe investigation of the Late Paleogene to Late Neogene species of rissoid gastropod Galeodinopsis in the Euro-Mediterranean area has supported the hypothesis that this genus is an intermediate form between two well-known rissoids,
Alvinia and Manzonia. We recognized four species of Galeodinopsis: G. biangulata, G. germanica sp. nov., G. semperi
(new name for Rissoa duboisii), and G. tiberiana. The oldest (very Late Eocene/Oligocene) representatives of Galeodinopsis, G. biangulata, and G. semperi, share similar shell shape and microsculpture with Alvinia. This suggests that
Galeodinopsis originated from some Eocene species related to Alvinia. The new species represents the first occurrence
within Galeodinopsis of a combination of characters very close to those of Manzonia, above all the typical pitted microsculpture. We hypothesize that Manzonia evolved from Galeodinopsis rather than from the genera Alvania or Alvinia, as previously supposed. Galeodinopsis originated during the very Late Eocene/Oligocene in the North Sea Basin.
Afterwards it underwent a strong southward shift to the mid-high east Atlantic and the Mediterranean area, during the
Mio-Pliocene, and to the Recent tropical eastern Atlantic coasts, where the type species G. tiberiana still lives. The shift
likely was due to a combination of climate cooling and palaeogeographical changes. The distribution of G. biangulata
suggests that connections between the North Sea Basin and the Atlantic domain opened through the Channel area at
least during the Early Oligocene, earlier than indicated previously. The distribution of Manzonia moulinsi supports the
idea of a southern connection to the Atlantic Aquitaine Basin via the Rhine Graben during the Late Oligocene. From a
palaeoecological point of view, Galeodinopsis includes warm species with planktotrophic larval development that are
typical of the shelf environment in fully marine condition
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
Alvania acida sp. nov., a new late Quaternary gastropod adapted to the shallow-marine CO2 seep of Vulcano Island
No full textSubmarine CO2 emissions are a recent (probably younger than about 5 ka) expression of volcanism at Vulcano Island (off NE Sicily), a Mediterranean natural laboratory for the study of ocean acidification. An impoverished molluskan association is known from the naturally acidified waters of Vulcano, at Levante Bay, where pH drops to 5.64. Here we describe a new gastropod, Alvania acida sp. nov., living in the bay, and found at the nearby site of Capo Milazzo (NE coast of Sicily) within a Late Pleistocene paleocommunity related to vegetated bottoms. The study species underwent a habitat change during its short evolutionary history, resulting in the recent adaptation to the CO2 seep at Vulcano. Similarly to the gastropods Tritia corniculum and T. neritea from the same seep, A. acida was up to 24% smaller than fossil shells from Milazzo, showing a further probable case of adaptation to high-CO2 waters through dwarfing. The new species shows distinctive features: an inflated shell; very convex, axially ribbed whorls; weak spiral cords. Because of its current distribution, limited to Levante Bay, and anthropogenic pressure from tourism affecting the site, A. acida deserves protection
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
A new Miocene deep-sea chiton and early evidence for Teredinidae-sustained wood-fall communities
Full text linkDeep-sea wood-falls are important biodiversity hot spots for insights on chemosynthesis-based communities. The study of deep-sea wood-fall-related palaeocommunities from the Neogene of north Italy shed light on interesting associations from the Miocene of Torrente Cinghio (Tortonian) and of Moncasale di Casina (Langhian). The most common components of this association are typical chemosynthetic/wood-fall molluscs, such as the gastropods Homalopoma sp. and Pseudonina bellardii, the bivalves Idas sp. and shipworms, and the chiton Leptochiton lignatilis n. sp., which belongs to a genus typical of recent sunken woods in tropical waters. The new species described is compared with other fossil and recent congeners, especially with those sharing the same kind of tegmental sculpture, fully covered with randomly or quincuncially arranged granules. An overview of the sunken wood-related chitons is provided. Surprisingly no taxa of the boring bivalves of the family Xylophagidae, whose species have been known to be fundamental for sustaining this kind of deep sea chemosynthetic ecosystem, were found in the studied site; however, other boring Teredinidae bivalves have been abundantly recovered. This suggests that, conversely to what has previously been observed on sunken wood communities, Teredinidae may be viewed as a counterpart for the maintenance of deep-sea wood-fall ecosystems
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