1,720,957 research outputs found
Evidence of two Holocene phreatomagmatic Eruptions at Stromboli volcano (Aeolian Islands) from paleomagnetic data
No full textWe present detailed stratigraphic-sedimentological and
paleomagnetic analyses of Holocene phreatomagmatic
deposits at Stromboli volcano (Aeolian Islands, Italy). The
investigated deposits belong to the Secche di Lazzaro
succession (SDL) and to the Advanced Operations Center of
the Department of Civil Defense (COA) succession, both
lying on the Neostromboli lavas (ca. 13 – 5 ka). The two
stratigraphic successions have similar stratigraphic position
and show a phreatomagmatic origin, likely related to
catastrophic magma-water interaction processes during
sector collapse events. However the thermal remanent
magnetization data of the lava lithics indicate that deposits
of the SDL succession were emplaced at very low
temperatures (less than 140
the COA deposit was emplaced at temperatures between
300 – 340
investigated deposits may be related to two distinct
eruptive events occurred during the Holocene. Recent
phreatomagmatic activity at Stromboli apparently has
occurred more frequently than previously believed.
Cons equent l y, we mus t r econs i der t he r ecur r ence
i n t e r v a l o f t h i s d a n g e r o u s e r u p t i v e s c e n a r i o f o r
Stromboli
The Holocene Secche di Lazzaro phreatomagmatic succession (Stromboli, Italy): evidence of pyroclastic density current origin deduced by facies analysis and AMS flow directions
No full textThe edifice of Stromboli volcano gravitationally
collapsed several immediately after the lateral collapse, which wrapped around
col l aps ed s ever al t i mes dur i ng i t s vol cani c hi s t or y
(>100 ka–present). The largest Holocene event occurred
during the final stage of the Neostromboli activity (∼13–
5 ka), and was accompanied by the emplacement of
phreatomagmatic and lahar deposits, known as the Secche
di Lazzaro succession. A stratigraphic and paleomagnetic
study of the Secche di Lazzaro deposits allows the
interpretation of the emplacement and the eruptive process-
es. We identify three main units within the succession that
correspond to changing eruption conditions. The lower unit
(UA) consists of accretionary lapilli-rich, thinly bedded,
parallel- to cross-stratified ash deposits, interpreted to
indicate the early stages of the eruption and emplacement
of dilute pyroclastic density currents. Upward, the second
unit (UB) of the deposit is more massive and the beds
thicker, indicating an increase in the sedimentation rate
from pyroclastic density currents. The upper unit (UC) caps
the succession with thick, immediately post-eruptive lahars,
which reworked ash deposited on the volcano’s slope. Flow
directions obtained by Anisotropy of Magnetic Susceptibil-
ity (AMS) analysis of the basal bed of UA at the type
locality suggest a provenance of pyroclastic currents from
the sea. This is interpreted to be related to the initial base-
surges associated with water–magma interaction that occurred the shoulder of the sector collapse scar. Upward in the
stratigraphy (upper beds of UA and UB) paleoflow directions
change and show a provenance from the summit vent, pro-
bably related to the multiple collapses of a vertical, pulsatory
eruptive column
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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