1,721,359 research outputs found
Aspects of the micropalaeontology of Devonian strata of North Devon
No full textAn integrated micropalaeontological investigation has been made of a ca.3km thick continuous sequence of Devonian strata in north Devon (S.W. England), encompassing the Lynton Formation, Hangman Sandstone Group, Ilfracombe Slates and Morte Slates. The sequence comprises interdigitated marine and non-marine sediments of low greenschist metamorphic facies: fossils have previously been considered rare in this succession. Low abundance, icriodid-dominated conodont faunas have been recovered from the Lynton Formation and the Ilfracombe Slates: in total, 33 pectiniform conodont taxa are reported. Polygnathids are confined in their recovery to the Ilfracombe Slates. Despite the uniformly low total organic carbon content of the rocks (0.1-0.3%), diverse palynofloras have been isolated from the marine, or marine-influenced sediments. Initial problems of the oxidation and temporary stability of opaque phytoclasts were overcome, and assemblages found to be dominated by well preserved, terrestrially-derived organic matter, comprising miospores, tetrads, and wood. Acritarchs, chitinozoa and scholecodonts are infrequent. Over 130 species of miospore are described, in addition to 29 acritarch taxa, 11 forms of chitinozoa, and a diverse suite of scolecodont and wood morphotypes. The influence of reworking proved difficult to assess, due to the low yields and generally good preservation of the material. Age determinations are based largely on the miospore assemblages, although conodonts provide independent corroborative evidence. The palynostratigraphy established for north Devon is compared with the zonal schemes of Richardson & McGregor (1986) and Streel et al., (1987). Based on miospore data, the Lynton Formation is interpreted as no older than latest Emsian in age, with the uppermost horizons and overlying Hollowbrook Formation of possibly earliest Eifelian age. Conodont faunas recovered from the isolated, inland section at Watersmeet (of uncertain stratigraphic position, but ?located within the lower third of the exposed Lynton Formation), are of ealy Eifelian aspect. The nonmarine Trentishoe Formation and the majority of the Rawns Formation proved barren. The sediments of the upper Hangman Sandstone Group yielded comparatively abundant, diverse miospore assemblages of ?mid-late Eifelian age. The overlying lower Ilfracombe Slates are interpreted as earliest Givetian in age. Conodont faunas recovered from the Rillage, Holey, Combe Martin Beach and David's Stone Limestone Members are indicative of the Lower/Middle varcus conodont Subzones (≈mid Givetian). The upper Combe Martin Slates are considered late Givetian in age, with the conformably overlying Kentisbury Slates attributable to the Frasnian Stage. A marked depletion in the miospore assemblages approximates to the Kentisbury/Morte Slates boundary. The Morte Slates yielded miospores and acritarchs typical of the Frasnian Stage, although the topmost horizons may possibly be of earliest Famennian age. The conodont faunas are interpreted as pectiniform lags. The sole recovery or predominance of Icriodus over narrow-platformed polygnathids suggests that a shallow-water marine environment prevailed during the deposition of parts of the Ilfracombe Slates. A detailed palynofacies study of the sequence was limited by the paucity of indigenous marine palynomorphs. However, a distinct dependency between scolecodont occurrence and the more proximal, shallow-marine facies has been observed. An extensive geothermometry study integrated conodont C.A.I. values and vitrinite reflectance data. Vitrinite reflectivity is uniformly high throughout the studied sequence, and the lack of dependency of Rm on stratigraphic position suggests that coalification was syn-orogenic. By applying the time independent conversion formula of Barker & Pawlewicz (1986) to this vitrinite data, the sediments are interpreted as having been influenced by temperatures in excess of 300^oC. This study demonstrates the value of integrating both palynological and conodont data in a regional biostratigraphical study, and furthermore identifies the Devonian sequence of north Devon as an important, continuous reference section for Devonian miospore palynostratigraphy.</p
Stanback (Thomas M.) et Knight (Richard V.) - The Metropolitan Economy.The Process of Employment Expansion.
No full textDerycke Pierre-Henri. Stanback (Thomas M.) et Knight (Richard V.) - The Metropolitan Economy.The Process of Employment Expansion.. In: Revue économique, volume 24, n°2, 1973. pp. 348-349
Stanback (Thomas M.) et Knight (Richard V.) - The Metropolitan Economy.The Process of Employment Expansion.
No full textDerycke Pierre-Henri. Stanback (Thomas M.) et Knight (Richard V.) - The Metropolitan Economy.The Process of Employment Expansion.. In: Revue économique, volume 24, n°2, 1973. pp. 348-349
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
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