1,721,012 research outputs found
Coastal response to climate change: Mediterranean shorelines during the Last Interglacial (MIS 5)
No full textThe response of shorelines to climate change is controlled by fall and rise of the sea level and by the
alteration of the coastal environment due to changing fluvial discharge and biological activity. In the
Mediterranean this response is complicated by the geographic proximity of the North Atlantic and the
African Monsoon climate systems, by a time and space specific interaction of eustatic and water-load
components of sea level and by the mid-latitudinal time lag between orbital forcing and terrestrial
response. Here, six Mediterranean coastal records are presented which contribute to our understanding
of how mid-latitudinal coasts respond to orbital forcing. The sediment sequences show sharp switches
between siliciclastic- and carbonate-dominated nearshore environments where carbonate-rich sediments
are composed of oolitic grainstones. From modern analogues it is deduced that the oolitic sediments
represent a period of relatively high annual sea-surface temperature and lack of fluvial discharge.
The warm-arid period was recorded at w114 ka on the southeast Iberian coast, at w113 ka on the Levant
coast, at w110 ka on the coast west of the Nile delta and at w83 ka on the north Saharan coast. It lasted
10e20 ka in east (Levant coast) and west (Iberian coast) and lasted 40 ka or more in the central-south of
the east Mediterranean. Timing and duration of the coastal proxy allow inferring instantaneous and
dominant response to external forcing in the east and west and delayed and prolonged response due to
dominant regional forcing in the centre of the East Mediterranean. A 9 m eustatic sea-level highstand
during MIS 5e is suggested with a start of the subsequent sea-level fall at w118 ka while evidence for
multiple MIS 5e highstand and a highstand during MIS 5a remain elusive
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Aeolian beach ridges and their significance for climate and sea level: Concept and insight from the Levant coast (East Mediterranean)
No full textRelict beach ridges of aeolian origin and associated soils are often used for inferring relative sea level and climate with contrasting results. Most studies link the aeolian coastal deposits to regres-sive phases, some to high sea-level stands, and a few to intermediate relative sea-level positions.
We interpret the apparent contradictions as indicating the lack of an over-arching concept and the inconsistent usage of sea level-related terms. In this paper we present an integrated morpho-sedimentological concept for a microtidal, mid-latitudinal coast and review existing data from the Levant (East Mediterranean) coast to evaluate the concept and to eliminate nomenclatural confusion.
A coastal depositional environment in a semi-arid environment consists of shallow-marine, aeolian and alluvial facies which together form an aeolian beach-ridge complex as a package of strata which respond simultaneously to sea-level change. A transgressive complex forms through reworking or overstepping of the coastal foredune and a regressive complex forms by downstepping. Under transgression the aeolian beach ridge represents the highstand deposit and its adjacent shallow marine sediment is the transgressive deposit. Under regression the complex represents the falling stage and the associated downdip surface marks the lowstand.
On the Levant coast we find chronologically well-constrained, offlapping aeolian beach ridges as parts of six downstepping beach ridge complexes formed between ~200 ka and 10 ka. The complexes represent the falling stage systems tract (FSST) of a short-lived (5th-order) depositional sequence when the shoreline shifted from a position close to the modern coastline to the shelf or below the shelf edge. Three of these FSSTs and their up dip and down dip super bounding surface together form the 4th order (~100 ka) sequence of the last interglacial/glacial cycle.
The absence of transgressive, highstand and lowstand systems tracts is explained by the poor pres¬ervation potential due to the small sediment budget of the complex. The falling stage complex has a high preservation potential because sediment source area increases while the sand drift potential remains above the local threshold. On the Levant coast, sand delivery to the backshore continued during relative sea-level falls for distances of up to 10 km between dune and coastline which is un¬precedented in most modern analogues.
The significance of the dune-soil succession for climate is limited because the dunes are governed by relative sea-level change; the vegetation response to changes in precipitation is non-linear and the dune dynamics are characterised by low resilience and hysteresis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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