1,721,025 research outputs found
The Godrevy dog; Early canine or lost pet?
No full textDuring sampling of the late Devensian St. Loy Member of the Penwith Formation at Godrevy, Cornwall, several ribs and vertebrae were discovered within the cliff face. The visible bones appeared in context with the surrounding geology with no evidence for later site disturbance or burial. During the excavation the skeleton was entirely enclosed within the coarse grained head deposits. The skeleton was articulated and nearly complete and is identified as Canis familiaris, the"domestic" dog. The recovery of this skeleton from the St. Loy Member of the Penwith Formation, generally regarded to be of mid to late Devensian age, is scientifically problematic. The accepted age for the late Devensian is 12-15,000 years BP. The oldest known domestic dogs are dated at about 10,000 years BP, although the burial of a dog or wolf puppy with a human skeleton from Israel 12,000 yrs BP is taken as early evidence of domestication. There are three possible interpretations: (1) the St. Loy Member of the Penwith Formation is younger than previously thought; (2) that Godrevy dog is a very early domestic dog; (3) that it is possible to incorporate a rcent articulated dog skeleton into Quaternary head deposits without any signs of physical disturbance at the site. Dating of the right radius bone by accelerator mass spectrometry has given a likely age for the skeleton of between 1620 AD and 1680 AD. Thus a 17th century domestic dog has been enclosed within Devensian coarse grained head deposits with no signs of disturbance to the site
Cretaceous-Tertiary high-latitude palaeoenvironments, James Ross Basin, Antarctica: Introduction
No full textThe James Ross Basin, at the northern tip of the Antarctic Peninsula, provides the thickest and best-exposed onshore Cretaceous and Early Tertiary sedimentary succession in Antarctica. When compared with other onshore sections, it is clear that the area has a much broader significance as a key reference section for the Cretaceous and Early Tertiary throughout the Southern Hemisphere. The sedimentary record exposed within the basin also provides an unrivalled opportunity to unlock the record of climate change and biotic response within a high-palaeolatitude setting.
James Ross Island was first visited during the heroic age of polar exploration at the start of the 20th century. Swedish geologist Otto Nordenskjöld sailed into the region in 1901 in his ship Antarctic, captained by explorer and sealer Carl Larsen. Plans to spend a year in the region for scientific exploration went disastrously wrong when his ship sank near Paulet Island, forcing Nordenskjöld to spend over 2 years in a small hut on Snow Hill Island. Members of his ship-wrecked party survived in horrific conditions, with only penguins for food and small stone huts for shelter at Hope Bay, at the tip of Trinity Peninsula, and also on Paulet Island.
Nordenskjöld’s enforced stay in the area was, however, not unprofitable. In 1902 he and his five companions made trips over the sea ice to Seymour Island, where they made the first important fossil discoveries, including the bones of giant penguins (now known to be from the Eocene La Meseta Formation). This was well before Scott’
Mid-Cretaceous stratigraphy of the James Ross Basin, Antarctica
No full textThe extensive Cretaceous sedimentary sequence exposed within the James Ross Basin, Antarctica, is critical for regional stratigraphic correlations in the Southern Hemisphere, and also for our understanding of the radiation and extinction of a range of taxonomic groups. However, the nature and definition of Cenomanian-Turonian strata on the NW margins of James Ross Island has previously been difficult, due both to marked lateral facies changes and to stratigraphical discontinuities within the extensive Whisky Bay Formation. Facies variation and local unconformities were the result of fault-controlled deep-marine sedimentation along the basin margin. In this study the Albian-Cenomanian boundary is defined for the first time in the upper levels of the Lewis Hill Member of the Whisky Bay Formation. However, there is a Cenomanian-late Turonian unconformity between the Lewis HIll and Brandy Bay members of the Whisky Bay Formation. Equivalent lithostratigraphical units exposed further to the SW on James Ross Island appear to be more complete with the early Cenomanian-late Turonian interval represented by the upper parts of the Tumbledown Cliffs and the lower part of the Rum Cove members of the Whisky Bay Formation. The Turonian-Coniacian boundary is provisionally placed at the junction between the Whisky Bay and Hidden Lake formations. The revised stratigraphic ages for this section show that the Late Cretaceous radiations of a number of major plant and animal groups can be traced back to at least the Turonian stage. This raises the possibility that their dissemination might be linked to the global Cretaceous thermal maximum
Geochemical and mineralogical record of historical mining, Hayle estuary, Cornwall, UK
No full textThe release pf particulate waste as a result of major historical mining activity within the polymetallic Cornubian orefield, Cornwall UK, has locally caused significant contamination of estuarine sediments. In this study the impact of historical mining on the southwest Hayle Estuary, Cornwall, UK, was evaluated by examining the sediment geochemistry and mineralogy of nine shallow (<1 m) cores along with surface sediment sampling throughout the intertidal areas of the estuary. The sediment geochemistry of ll of the cores shows very elevated levels of tin and copper (maximum Sn value of 7041 ppm and Cu 29,869 ppm). Surface (uppermost 5 cm) sediment samples are also contaminated, with up to 4520 ppm Cu, 5455 ppm Sn, 2292 ppm As, 522 ppm Pb and 1777 ppm Zn. Core dating indicates that the sediments currently exposed at the surface were deposited prior to 1880. The detrital heavy mineral assemblage is dominated by cassiterite, chalcopyrite, arsenopyrite, sphalerite and pyrite along with minor galena, monazite, zircon, stannite, wolframite, plumbogummite, covellite, bornite and ilmenite. In addition, man made slag and smelt products are common. Diagenetic pyrite, chalcopyrite and atacamite are also present. The sediment geochemistry and mineralogy are interpreted to represent (a) the input of historic mine waste tailings and smelt waste into the estuary probably prior to 1880, and (b) the subsequent exposure of these contaminated sediments as a result of recent erosion
Impact of mining on the sediment geochemistry and Mineralogy of the Helford river, Cornwall
No full textThe geochemistry and mineralogy of the intertidal sediments of the Helford River, Cornwall have been examined to assess the potential impact of mining activity on sediment supply. Cores from Polpenwith and Polwheveral creeks show a pulse in Sn (1000-1100 ppm), Cu (800-900 ppm) and Zn (500-600 ppm) at a depth of 30 cm below the present day sediment surface; As and Pb values are typically low and show little down-core variation (<130 ppm As and <78 ppm Pb). Two cores recovered near Gweek have generally low and invariant down-core geochemical signatures, except for a single sample from the base of Core 2 which shows a sudden increase in Sn to >1800 ppm. In addition, two cores were collected from the mouth of Mawgan Creek. Core 4 shows a low but invariant geochemical signature but Core 3 shows a significant down-core increase in Sn (>1900 ppm Sn), Cu (588 ppm) and Zn (1297 ppm). The heavy mineral assemblage is dominated by cassiterite, chalcopyrite and sphalerite, along with less abundant zircon, monazite, ilmenite, rutile/anatase, sphene, wolframite, barite and rare slag products. Diagenetic pyrite, bornite and Fe oxides also occur. The geochemistry and mineralogy are consistent with the historical release of mine waste tailings into the Helford River. 210Pb dating of two cores suggests that the sediments are younger than 1880. Based on these data the most likely sources of the mine waste are from Wheal Caroline and Wheal Vyvyan to the north of the Helford River which are documented as being active between 1827 and 1864
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
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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