1,721,206 research outputs found
Restrictions to the application of 'diagnostic' criteria for recognizing ancient seismites
No full textSoft-sediment deformation structures induced by seismic liquefaction and/or fluidization receive much attention in sedimentological, structural and palaeoseismic studies. The direct record of larger earthquakes is restricted to instrumental and historical data; the recognition of prehistoric earthquakes requires criteria to recognize seismites in the geological record. The areal distribution of seismites can sometimes be related to active faults since distances to the epicenter (for a given magnitude) tend to be related to the liquefaction effects of seismic shocks.
The use of soft-sediment deformation structures for palaeoseismic studies has limitations, however. Hardly anything is known, for instance, about the effects that modern seismic events have on the sediments in most environments. Moreover, criteria for the recognition of seismites are still under discussion. The following characteristics seem, particularly in combination, the most reliable: (1) Soft-sediment deformation structures should occur in laterally continuous, preferably recurring horizons, separated by undeformed beds; (2) These deformation structures should be comparable with structures known to have been triggered by modern seismic activity; (3) The sedimentary basin should have experienced tectonic activity at the time when the deformations were formed; and (4) The intensity or abundance of the soft-sediment deformation structures in a presumed seismite should change laterally, depending on the distance to the epicenter. It turns out that all of these four criteria have important exceptions. (1) Soft-sediment deformation structures occurring over large lateral distances in a specific layer can be triggered also by other processes. Moreover, in environments with a low sedimentation rate, the time between successive earthquakes is often too short to allow accumulation of beds that remain undisturbed. Furthermore, total liquefaction of a sandy bed may result in the absence of deformation features. (2) No truly diagnostic soft-sediment deformation structures exist to prove seismic activity. Moreover, the final configuration of a soft-sediment deformation structure is independent of the type of trigger. (3) Seismites occur frequently in areas where seismic activity is low today. (4) The lateral changes in the intensity of soft-sediment deformation structures in seismites as a factor presumed to depend on the distances to the epicenter, pose a complicated problem. The 2012 Emilia earthquakes, for instance, affected sandy fluvial channels but not the fine-grained floodplains.
It must thus be deduced that specific soft-sediment deformation structures cannot be used without additional evidence to identify seismites. In particular, the magnitude of seismic shocks and the recurrence time of main events (the most important features that allow recognition of seismites) seem to be sedimentological in nature: facies changes in space and time seem the parameters that most strongly control the occurrence, morphology, lateral extent and the vertical repetition of seismites
Assessing baseflow index vulnerability to variation in dry spell length for a range of catchment and climate properties
Full text linkBaseflow index (BFI) prediction in ungauged basins has largely been based on the use of catchment physiographic attributes as dominant variables. In a context where changes in climate are increasingly evident, it is also important to study how the slow component of flow is potentially affected by climate. The aim of this study was to illustrate the impact of climate variability on the baseflow process based on analysis of daily rainfall characteristics and hydrological modelling simulation exercises validated with observed data. Ten catchments were analysed that span southern to northern Europe and range from arid Mediterranean to maritime temperate climate conditions. Additionally, more than 2,000 virtual catchments were modelled that cover an extended gradient of physiographic and climate properties. The relative amounts of baseflow were summarized by the BFI. The catchment slow response delay time (Ks) was assumed to be a measure of catchment effects, and the impact of climate properties was investigated with the dry spell length (d). Well-drained and poorly-drained groups were identified based on Ks and d, and their response to an increase or decrease in dry spell length was analysed. Overall, for either well- or poorly-drained groups, an extension in dry spell length appeared to have minor effects on the baseflow compared with a decrease in dry spell length. Under the same dry spell variation, the BFI vulnerability appeared higher for catchments characterized by large initial d values in combination with poorly-drained systems, but attributing an equal weight to the variations in d both in the case of dry and wet initial conditions, it is in the end concluded that the BFI vulnerability appears higher for systems laying in the transition zone between well- and poorly-drained systems. Copyright © 2018 John Wiley & Sons, Ltd
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
Invloed van sterische belemmering van mesomerie op de absorptiespectra van amino-azoverbindingen in neutraal en zuur milieu
No full textDelftChemTec
Technische bereiding van Teflon (=polytetrafluoraetheen)
No full textDocument(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science
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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