1,720,962 research outputs found
Chemical reactivity of pozzolans from Sardinia for the industrial production of hydraulic limes
Full text linkThe research is aimed at studying the chemical reactivity between lime and volcanic rocks belonging to different Sardinian outcrops, for a use as raw material in the production of hydraulic / pozzolanic limes. On the basis of preliminary geochemical and mineralogical-petrographic investigations, several volcanic rocks from basic-intermediate to acid in composition (substantially from andesitic, to dacitic, to rhyolitic) have been selected and used for to perform laboratory reactivity tests. These rocks differ in the variable content of glass (from 15% to about 95% in volume), due to the presence of secondary minerals, and to physical properties (density, porosity, water absorption, etc.). The physical characteristics are essentially linked to the different compositional incidence of the crystalline, crystal-clastic, lithic (present in some pyroclastic facies), type and quantity of glass phases, to their different methods of installation (conditioned by temperature, chemical composition, grade welding, etc.), and to the different degree of alteration. The results of the investigations on the pozzolan materials (by polarized light microscopy, XRD, SEM, EPMA-WDS, Chapelle test) show that following parameters affect the chemical reactivity of the volcanic products with lime: i) quantity and type of amorphous phases (glass), linked to the different emplacement of volcanic rocks (affected by temperature, chemical composition, welding grade, etc.), ii) compositional incidence of the crystalline phases, crystal-clasts, lithics (these latter present in some pyroclastic facies), iii) alteration grade of the rocks and presence of secondary minerals (e.g., zeolites, phyllosilicates, etc.)
An archaeometric contribution to the study of ancient millstones from the Mulargia area (Sardinia, Italy) through new analytical data on volcanic raw material and archaeological items from Hellenistic and Roman North Africa.
No full textThe main quarrying area of the Mulargia ignimbrite, used mainly to produce rotary millstones during the
Hellenistic and Roman age, has been identified and sampled in order to update and complete the
petrographic and geochemical database by employing standard analytical methods (optical microscopy
and ICP-AES/MS spectrometry). The combination of petrographic and geochemical data concerning the
Tertiary rhyodacitic to rhyolitic ignimbrites outcropping in central west Sardinia, previously very poor,
form a helpful tool for future work on this important typology of volcanic millstones. The data bank
obtained has been used to verify the geological source of eight millstones discovered in different rural
settlements of Hellenistic Numidia and Roman Africa Proconsularis supposed by archaeologists to be
made of ignimbrite from Mulargia. The results of the petro-archaeometric study confirmed a Sardinian
origin for these millstones and represent one of the very few analytical proofs of their effective export to
North Africa
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
- …
