1,720,981 research outputs found
Materiali vetrosi protostorici dal Sud Italia: caratterizzazione chimica e studio degli elementi in traccia
No full textQuesto progetto è finalizzato allo studio archeometrico del vetro protostorico proveniente da diversi siti dell’Età del Bronzo e del Ferro del Sud Italia. Lo scopo è la definizione delle materie prime (vetrificanti, fondenti, coloranti, opacizzanti) e della tecnologia impiegata per la produzione di questi manufatti, in modo da seguirne l’evoluzione nel tempo. Ad oggi una grande quantità di dati archeologici e archeometrici relativi a vetri del nord Italia è disponibile in letteratura, al contrario solo pochi campioni provenienti dal sud Italia sono stati analizzati. Dunque questo progetto prende in esame 132 campioni di vetro provenienti da Pompei, Vivara, Murgia Timone, Broglio, Lipari, Roca Vecchia -siti datati dal Bronzo Antico (24° sec. a.C.) al Bronzo Finale (10° sec. a.C.) - e da Francavilla, Torre Galli, Cuma, Capua, Sarno e Amendolara –siti dell'Età del Ferro (10°-6° sec. a.C.). I frammenti di vetro prelevati sono stati inglobati in resina epossidica, lucidati con pasta diamantata ed analizzati tramite ESEM, EMPA e LA-ICPMS. L'analisi dettagliata degli elementi maggiori e minori ha permesso la distinzione di sei gruppi chimici. In particolare: vetri ad alcali misti, vetri al natron, vetri alle cenere di piante, vetri ad alto alluminio, vetri blu cobalto e vetri neri. L'analisi degli elementi in traccia mostra come le variazioni composizionali del set siano strettamente coerenti con il raggruppamento definito tramite la chimica dei maggiori e minori, consentendo inoltre ulteriori sotto-raggruppamenti. I vetri ad alcali misti sono stati prodotti con una sabbia povera di minerali pesanti. I vetri al natron sono divisi in due gruppi: uno ad alto Zr-Hf prodotto con una sabbia mineralogicamente matura, ricca di quarzo e zircone e relativamente impoverita in altri minerali pesanti; e uno basso Zr-Hf prodotto con una fonte di silice davvero pura, forse ciottoli di quarzo. Il vetro nero è stato prodotto con sabbia molto impura ricca di ossidi di ferro (ad esempio la magnetite), e minerali pesanti (zircone-Y; HREE-granato; monazite-LREE). Il vetro blu cobalto invece mostra una composizione che dipende dall’allume cobaltifero utilizzato come colorante. Il vetro HIGH-allumina mostra i più alti livelli di tutti gli elementi in traccia, suggerendo l'uso di una sorgente di sabbia estremamente impura, ricca di minerali di Fe, argilla e feldspati. I vetri alle ceneri di piante sono stati prodotti con una sorgente di quarzo puro, nel caso dei vetri ad alto cerio esso può suggerire l'uso di una fonte vetrificante diversa contenente una maggiore quantità di minerali arricchiti in terre rare leggere, come monazite. Riguardo l’evoluzione della tecnologia produttiva, si può osservare che per i materiali del Bronzo Antico-Medio è stata impiegata la tecnologia delle ceneri di piante. Questo dato era previsto in quanto la produzione del primo di vetro (in Mesopotamia) era di questo tipo. La presenza del vetro ad alcali misti in siti di Bronzo Finale è coerente con la sua produzione in Europa durante questo periodo. In particolare il sito di Frattesina è l'unico ad oggi riconosciuto per la produzione di vetro con questa particolare composizione. Dunque il vetro trovato nei siti di Bronzo Finale del Sud Italia, suggerisce l'interruzione degli scambi con il Vicino Oriente in questo periodo e l'importazione di vetro dal nord del paese. Infine si è osservata la presenza di vetro al natron (nero e blu cobalto) già nel periodo di transizione con l'Età del Ferro. Fino ad oggi la diffusione di questo tipo di vetro è stata attestata dal 8°-7° secolo a.C., ma i materiali qui analizzati dimostrato che una precoce diffusione, corrispondente alla prima produzione di vetro natron in Egitto nel 10°-9° sec. a.C., era già in attoThis project is focused on the archaeometrical study of protohistoric glass coming from several Bronze and Iron Age sites of Southern Italy. The aim of the project is the definition of the raw materials (vitrifying, fluxes, colorants, opacifiers) and of the technology employed for the production of these artifacts, in order to follow their evolution in time. A large amount of archaeological and archaeometrical data about glass of Northern Italy is available in literature, on the contrary only a few samples from Southern Italy have been analyzed up to now. Therefore my PhD thesis examines 132 glass samples coming from Pompei, Vivara, Murgia Timone, Broglio, Lipari, Roca Vecchia –sites dated from the Early Bronze Age (24th century BC) to the Final Bronze Age (10th century BC)- and from Francavilla Marittima, Torre Galli, Cuma, Capua, Sarno and Amendolara -pertain to the Iron Age (10th-6th century BC). This study was carried out with a multi-technique approach. The sampled material was embedded in epoxy resin and polished with diamond paste, to be analysed by ESEM, EMPA and LA-ICPMS. The detailed analysis of the major and minor compositions allowed the distinction of six different chemical groups. Specifically we can recognised: mixed alkali glass, natron glass, plant ash glass, high-alumina glass, cobalt blue glass and iron black glass. The trace elements analysis shows how the compositional variations of the sample set are strictly consistent with the grouping found with the major and minor element chemistry. MIXED ALKALI glass was produced with a sand poor in heavy minerals. The NATRON glass are split into two groups: High Zr-Hf produced with a mineralogically mature sand, rich in quartz and zircon and relatively depleted in other heavy minerals; and Low Zr-Hf produced with a really pure silica source, perhaps quartz pebbles. The IRON BLACK glass was produced with very impure sand rich in iron oxides (e.g. magnetite), and heavy minerals (zircon-Y,HREE-garnet, monazite-LREE). The COBALT BLUE glass instead shows a trace and REEs composition related to the cobaltiferous alum used as colourant. The HIGH-ALUMINA glass shows the highest levels of all trace elements, suggesting the use of a really impure sand source, rich in Fe-minerals, clay and feldspars. The PLANT ASH glass were produced with a pure quartz source, in the case of the High-Ce plant ash, the higher cerium can suggest the use of a different source containing a major amount of minerals enriched in LREEs, such as monazite. Taking into account the evolution of the technology employed for the glass production, we can observe that for the materials dated from the Early to the Middle Bronze Age the traditional PLANT ASH technology had been used. This was expected since the first production of glass, located in Mesopotamia, was of the plant ash glass type. The presence of MIXED ALKALI glass in Final Bronze Age sites of Southern Italy is consistent with its production in European Final Bronze Age. Specifically the site of Frattesina was the only one to produce glass with this peculiar composition. Therefore the glass found in the Final Bronze Age site of Southern Italy, suggests an interruption of trade with the Near East in this period and an importation of glass from the North of the country. Finally, at the transition with the Iron Age, the presence of NATRON glass(IRON BLACK and COBALT BLUE) is observed. To date the diffusion of this type of glass has been attested from the 8th-7th century BC, but the materials here analysed demonstrated that an early diffusion, corresponding to the first production of natron glass in Egypt in the 10th-9th cent. BC, was already presen
Ornamenti in materiale vetroso dell’età del bronzo dall’Italia meridionale e dall’area siciliano-eoliana: un inquadramento d’insieme alla luce di nuovi dati
No full textQuesto documento presenta i risultati di un ampio studio sui vaghi di collana in materiale vetroso dell'età del bronzo rinvenuti nell'Italia meridionale e nell'area siciliano-eoliana. La ricerca si basa su una ricognizione globale dei vaghi (diversi dei quali inediti, come nel caso di decine di esemplari dallo scavo di Punta di Zambrone), sulla loro classificazione tipologica e su nuove analisi archeometriche, effettuate su 36 campioni provenienti da: S. Abbondio (Pompei-NA), Grotta Cardini (Praia a Mare-CS), Vivara-Punta D’Alaca (Procida-NA), Murgia Timone (Matera-MT), Punta di Zambrone (Zambrone-VV), Torre Castelluccia (Pulsano-TA), Broglio (Trebisacce-CS), Roca (Melendugno-LE) e Lipari-Piazza Monfalcone (Lipari-ME). La gamma cronologica degli esemplari esaminati - molto più ampia di quella considerata finora - comprende l'intera età del bronzo, dalla fase antica (S. Abbondio) a quella fase finale (Lipari, Torre Castelluccia, Roca). Anche l'area geografica indagata è maggiore rispetto a quella finora studiata analiticamente. Lo studio archeologico e la classificazione tipologica hanno portato a una migliore definizione dei tipi e della loro distribuzione cronologica e geografica. Le analisi archeometriche hanno fornito informazioni sui metodi di produzione e sull'area geografica di origine dei materiali vetrosi. Dalla combinazione delle due serie di dati emergono nuove rilevanti prospettive sulla circolazione delle diverse produzioni
Different glassmaking technologies in the production of Iron Age black glass from Italy and Slovakia
Full text linkThis study presents the results of an archaeometrical investigation performed on 75 black glass beads dated to the ninth–fifth century BC coming from Bologna, Cumae, and Pozzuoli (Italy), and Chotin (Slovakia). The analyses of the major, minor, and trace elements—as well as that of Sr and Nd isotopes performed on a selection of samples coming from Bologna—provided evidence for two different production technologies in Iron Age black glass found in Italy (natron glass, probably produced in Egypt) and Slovakia (wood ash glass, probably produced in Europe). In both cases, the glasses derive their black colouration from the high presence of iron (around 12 % FeO), introduced into the glass batches through the intentional choice of dark sands. The production model appears to be small-scale and experimental, characterised by the use of non-sorted raw materials and poorly defined formulae, producing glass with a high chemical variability. The wood ash technology appears to have dropped out of use in Europe until the Medieval period, while natron production spread quickly, becoming predominant throughout the Mediterranean.status: Publishe
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
- …
