1,721,066 research outputs found
Neogene alkaline volcanism of the Afyon-Isparta area, Turkey: petrogenesis and geodynamic implications
No full textIn the Kirka-Afyon and Isparta areas, potassic and ultrapotassic alkaline magmatism followed Upper Eocene - Middle Miocene calc-alkaline volcanism, which was related to the northward subduction of the African Plate beneath Eurasia. The alkaline volcanism lasted from 14.8 Ma (in the north) to 4 Ma (in the south) and was associated with a presently still active extensional tectonic regime. It is mainly located along a N-S fault, which marks the limit between the Aegean Are and the Cyprus Are (Isparta Angle). In the Kirka-Afyon area the potassic to ultrapotassic rocks range from silica saturated (trachybasalts to trachytes) to highly undersaturated (phonolitic leucitites). In the Isparta area ultrapotassic rocks occur together with rhyolitic lavas. In both areas, the ultrapotassic magmatism is transitional between lamproitic and Roman type, with a more lamproitic character for the Isparta rocks. The potassic suites of both the Kirka-Afyon and Isparta areas are characterised by rocks with Sr isotope ratios increasing from mafic to silicic rocks. The rocks from Kirka-Afyon area have an orogenic affinity, whereas those from Isparta area exhibit orogenic (the potassic suite) and within-plate (the ultrapotassic suite) affinities. Extreme enrichments in LIL elements characterise the Afyon phonolitic leucitites, whereas enrichments in Sr and REE are observed in Isparta potassic rocks. A residual, probably lithospheric mantle metasomatised by fluids and/or melts of different origin (subduction-related for the Kirka-Afyon rocks; deep astenospheric origin for the Isparta rocks), is considered to be the source of the ultrapotassic magmas. A more "fertile" and probably deeper mantle, enriched by subduction-related components, is believed to be the source of the potassic rocks. Lower degrees of partial melting, in the mantle, at higher pressure, and probably at higher X-CO2, may account for the genesis of the phonolitic leucitite parental magmas. Partial melting of the mantle took place simultaneously in both sources, probably due to post-collision extensional tectonics, which was also responsible for the uprise of deep astenospheric mantle
Simultaneous measurement of wall shear stress and arterial distension in FMD studies
No full textAbstract
In Flow-mediated dilation (FMD) studies, blood flow in the brachial artery is restricted for about 5 minutes by a cuff. When the restriction is removed, the subsequent increase in wall shear rate (WSR) stimulates the release of nitric oxide, a vasodilator, from the endothelial cells into the smooth muscle. Impaired FMD responses, which are considered independent predictors of possible cardiovascular events, should be reliably detected. While several efforts have been so far dedicated to measure the diameter change, the source of this change, i.e., the WSR increase, has not been measured so far. In this paper, first results of the simultaneous measurement of WSR and diameter performed during FMD studies in the brachial arteries of 15 volunteers are reported. All measurements were obtained through the ULtrasound Advanced Open Platform (ULA-OP). © 2010 IEEE.
Author keywords
arterial diameter measurement; Doppler; Flow-mediated dilation; wall distension; wall shear rate
Indexed Keywords
Arterial diameter; Doppler; Flow-mediated dilation; wall distension; Wall shear rates
Engineering controlled terms: Endothelial cells; Nitric oxide; Shear deformation; Ultrasonics
Engineering main heading: Shear flow
ISSN: 10510117 ISBN: 978-145770382-9 CODEN: PIEUESource Type: Conference Proceeding Original language: English
DOI: 10.1109/ULTSYM.2010.5935468Document Type: Conference Paper
Sponsors: IEEE Ultrasonics, Ferroelectrics, and,Frequency Control Society (UFFC
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
Simultaneous Ultrasound Assessment of Brachial Artery Shear Stimulus and Flow-Mediated Dilation During Reactive Hyperemia
No full textIn flow-mediated dilation (FMD) studies, brachial artery diameter changes due to reactive hyperaemia are typically measured through manual or automatic analysis of high resolution B-mode images while the stimulus of diameter change, i.e., the flow change, is qualitatively estimated by measuring the mean velocity in the vessel and assuming a parabolic velocity profile. This article describes an experimental approach to simultaneously measure the wall shear rate (WSR) and the diameter variations, through multigate spectral Doppler and B-mode image processing, respectively. By using an ultrasound advanced open platform (ULA-OP), experimental results from the brachial arteries of 15 presumed healthy volunteers have been obtained. The mean increments during reflow against baseline were 105% ± 22% for the peak WSR and 8% ± 3% for the FMD. The mean time interval between the WSR peak and the beginning of plateau of diameter waveform was 38 ± 8 s. The results confirm that in young healthy subjects the postischemic vasodilation of brachial artery is largely correlated to the WSR increase
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
Textural effects of steady state behaviour of the Stromboli feeding system
No full textThe exceptionally persistent activity of Stromboli volcano has lasted for at least 1400 years. The normal strombolian activity is periodically interrupted by more energetic explosions (1-2 per year) and by sporadic effusive episodes (every 10-20 years). Normal activity and effusive episodes are characterized by crystal-rich high-K to shoshonitic basalts issuing from a volatile-poor shallow system. Crystal-poor pumice are emitted only during more violent explosions, and are thought to derive from deep pulses of volatile-rich magma. Shallow level degassing induces massive crystallization of deep pulses of feeding magma that, continuously mixing with the resident one, produces the crystal-rich shoshonite of the persistent activity. We examined the crystallization history of the crystal-rich, shallow reservoir using plagioclase Crystal Size Distribution (CSD) analysis of scoriae and lavas emitted in the past twenty years. CSDs show a linear dependence from crystal size in the size interval 0.06-1.2 mm; number density of larger crystals is biased by right hand truncation effects. CSDs slopes and intercepts are quite constant during the whole considered time span revealing a system that is close to the equilibrium also from a kinetic point of view. The linear crystal size distribution are reached by the system through episodes of growth and resorption, respectively occurring in the degassed and undegassed magma during the continuous mixing in the feeding system. Plagioclase net growth rate (2 x 10(-11) cm/s) results from a balance of growth (10-(10) cm/s) and resorption episodes which induce spectacular zoning and resorption textures in crystals larger than 200 mu m. CSDs of mafic phases cannot be accurately acquired on each single sample due to poor counting statistics; the evaluation of pyroxene and olivine CSD on the whole data set, however, confirms the conclusions acquired from plagioclase CSDs. (c) 2006 Published by Elsevier B.V
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