1,721,144 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
The composition of noble gas and CO2 in the European subcontinental lithospheric mantle
No full textThis PhD thesis reports an integrated study of petrography and geochemistry of the minerals with noble gases and CO2 (when available) in fluid inclusions (FI) from selected mantle xenoliths erupted in Europe during alkaline magmatism. The aim of the thesis is to show how the occurrence of partial melting, metasomatism, refertilization, magmatic degassing, volatile recycling, and mixing of volatiles modified the pristine composition of fluids stored in European SCLM and give clues on its geodynamic evolution. Mantle xenoliths from a few key regions where magmatism occurred in different temporal and geodynamic conditions were selected: Lower Silesia (Eger Rift) in SW Poland, Persani Mts. (Transylvania) in Romania, Eifel and Siebengebirge in Germany.
The main outcomes of this thesis are:
-The chemistry of FI in mantle xenoliths from the studied areas revealed is dominated by CO2, with N2 as second major species. Noble gas are in trace. Oliv are systematically gas-poor respect to Px from the same xenoliths. Among Oliv from European xenoliths, those from Lower Silesia display the highest CO2 concentrations suggesting carbonated-like metasomatism, as also inferred from trace elements in cpx.
-Ne and Ar concentration and isotopic ratios indicate variable extents of contamination by atmosphere-derived fluids. This contamination is likely derived from the recycling into the mantle of atmospheric-derived material inherited by local/recent or fossil subduction. This is more evident in the xenoliths from Persani Mts., where a recent subduction occurred.
-Oliv and Px display variable extents of partial melting and metasomatism/refertilization, as indicated by the mineral chemistry and He/Ar* in FI. The highest degrees of melting (25-30%) are found in samples from Lower Silesia and Siebengebirge, which are also among the oldest within the suite of samples (>6 Ma). Evidences of low degrees of melting and/or refertilization are found in Persani Mts. and West Eifel, which are Quaternary. This suggests that refertilization process is likely occurred in Quaternary, postponing mantle melting still recorded in Lower Silesia and Siebengebirge.
-The 3He/4He corrected for air contamination (Rc/Ra) is within European SCLM range (6±1 Ra) that is lower than MORB (8±1 Ra). This indicates a widespread recycling of crustal material below Europe if compared to other continental rift (e.g., Antarctica, East African). However, the careful investigation of olivine, cpx, and opx in single localities allowed distinguishing variations of 3He/4He that are related to the local history of the mantle. In detail, Persani Mts. show the lowest 3He/4He values within the dataset that indicate highest degree of crustal recycling due to the recent subduction that plays an important role in contaminating the mantle. Instead, metasomatism involving asthenospheric MORB-like fluids well explains the highest 3He/4He values recognized in all the studied localities.
-Ne-Ar-He isotopic systematics indicates that most of the data fall along a mixing between air and a MORB mantle. The presence of a plume (lower mantle) beneath the studies localities can be excluded.
-I presented the first data of carbon isotope composition of CO2 (δ13C V-PDB) in the Lower Silesia mantle xenoliths, which suffered a metasomatism by carbonated-rich fluids. The δ13C values are about -3.9 ‰ and are within MORB range with <0.1% limestone contamination.
-The comparison of 3He/4He signature measured in mantle xenoliths from the three target areas with that of CO2-dominated gas emissions located within or nearby shows that only gases emitted along Eger Rift are representative of the local mantle signature, suggesting an active magmatic activity below this area. Instead, gases emitted in East Eifel and nearby Persani Mts. are slightly to strongly contaminated by crustal fluids during their rising toward the surface or are released from a cooling and aging magma residing within the crust.Questa tesi riporta lo studio integrato di petrografia e geochimica dei minerali con gas nobili e CO2 in inclusioni fluide (FI) di xenoliti di mantello eruttati in Europa durante il magmatismo alcalino. Lo scopo della tesi è mostrare come il verificarsi di fusione parziale, metasomatismo, rifertilizzazione, degassamento magmatico, riciclo e miscelazione di volatili nel mantello abbia modificato la composizione originaria del mantello litosferico sub-continentale Europeo e fornito indizi sulla sua evoluzione geodinamica. Sono stati selezionati campioni provenienti da alcune regioni in cui si è verificato il magmatismo in diverse condizioni temporali e geodinamiche: Bassa Silesia (Eger Rift) nella Polonia meridionale, Mt. Persani (Transilvania) in Romania, Eifel e Siebengebirge in Germania. I principali risultati di questa tesi sono:
-La composizione chimica delle FI negli xenoliti delle aree studiate è dominata dalla CO2, con N2 come seconda specie principale. I gas nobili sono in traccia. Le Olivine (Ol) sono sistematicamente povere di gas rispetto ai pirosseni (Px) degli stessi xenoliti. Tra i campioni studiati, le Ol della Bassa Silesia mostrano le più alte concentrazioni di CO2 che suggeriscono un metasomatismo carbonatato, come dedotto anche dagli elementi in traccia nei Px.
-La concentrazione ed i rapporti isotopici di Ne e Ar indicano variabili gradi di contaminazione da parte di fluidi atmosferici. Questa contaminazione è causata dal riciclo nel mantello di materiale derivato dall'atmosfera ereditato dalla subduzione locale, recente o fossile. Ciò è più evidente negli xenoliti di Mt. Persani, dove si è verificata una subduzione recente.
-Oliv e Px mostrano variabili percentuali di fusione parziale e metasomatismo/rifertilizzazione, come indicato dalla chimica dei minerali e dall’He/Ar* nelle FI. I più alti gradi di fusione (25-30%) si trovano in Bassa Silesia e Siebengebirge, che sono anche tra i più antichi all'interno della suite di campioni (>6 Ma). Bassi gradi di fusione e/o rifertilizzazione sono ipotizzati nei Mt. Persani e nella parte occidentale dell’Eifel, che sono quaternari. Ciò suggerisce che il processo di rifertilizzazione è avvenuto nel Quaternario.
-Le misure di 3He/4He corretto per la contaminazione dell'aria (Rc/Ra) rientrano nell'intervallo di valori noto per il mantello Europeo (6±1 Ra) e sono inferiori a quello MORB (8±1 Ra). Ciò indica un diffuso riciclo di materiale crostale al di sotto dell'Europa rispetto ad altre zone di rift continentale (ad es. Antartide, Africa orientale). Tuttavia, l'attenta indagine su Oliv e Px nelle singole località ha permesso di distinguere le variazioni di 3He/4He correlate alla storia locale del mantello. Nel dettaglio, i Mt. Persani mostrano 3He/4He più bassi, indicando il più alto grado di riciclo di materiale crostale nel mantello. Invece, il metasomatismo da fluidi astenosferici simili al MORB spiega i più elevati 3He/4He presenti in tutte le località studiate.
-La sistematica di Ne-Ar-He indica un trend di mescolamento tra l'aria e un mantello MORB e l’assenza di un contributo del mantello inferiore (plume) al di sotto dell’Europa.
-I primi dati sulla composizione isotopica del carbonio di CO2 (δ13C V-PDB) negli xenoliti del mantello carbonatato della Bassa Silesia indicano valori di circa -3.9 ‰, che rientrano nel range MORB con una contaminazione di carbonati <0.1%.
-Il confronto tra gli 3He/4He misurati negli xenoliti di mantello delle tre aree e quelli dei gas emessi all'interno o nelle vicinanze mostra che solo i gas emessi lungo l’Eger Rift sono rappresentativi della firma del mantello locale, suggerendo un'attività magmatica ancora attiva sotto quest’area. Invece, i gas emessi nell'Eifel e nelle vicine dei Mt. Persani sono variabilmente contaminati da fluidi crostali acquisiti durante la loro risalita verso la superficie o sono rilasciati da un magma in raffreddamento e invecchiamento all'interno della crost
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Influence of crack wake mechanisms on the dynamic fracture of multiply delaminated plates
No full textThe paper deals with the dynamic interaction of multiple delaminations in composite plates subject to out of plane loading. In order to develop a basic understanding of the problem, the work refers to the model system of a multiply delaminated plate deforming in cylindrical bending. Interaction effects on fracture parameters, dynamic crack growth, energy absorption and damage and impact tolerance are investigated. Large scale crack bridging mechanisms, such as those produced by a through-thickness reinforcement, strongly control and regularize the dynamic response of systems of stationary delaminations. In the free vibration phase that follows the removal of the load, the crack bridging action developed by a typical through-thickness reinforcement prevents out of phase vibrations and hammering of the delaminated layers and limits amplification of the fracture parameter
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
Analisi limite agli elementi finiti di archi in muratura interagenti col riempimento
No full textThe limit analysis of masonry bridges is faced/tackled by considering the interaction between arches, piers and fill. The former are modelled by beams made of no tensile resistant material while the latter as a heavy rigid-plastic material in the simplifying hypothesis of plane strain. On the upper surface of the fill traction distributions are applied and upper bounds of the load multiplier at collapse are ricercati/pursued by applying the kinematic theorem. The collapse mechanisms considered are based on approximations of the velocity field from a finite element discretization. The fill is modelled by triangular constant strain elements and the arches and piers by two node beams. In order to take into account possible discontinuities in the velocity field in the fill, four nodes rigid-plastic interfaces are located between the triangular elements. Once linearized the limit domains in the generalised stress space, externally tangent to the effective limit domains, a linear programming problem is defined and upper bounds for the applied increasing loads are obtained. Two example are analysed and discussed from which the relevant effects of the fill on the collapse mechanism and multiplier are shown; finally, the sensitivity of the collapse multiplier on the mechanical parameters of the fill such as the coesion coefficient and the angle of internal friction is obtained
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