1,721,141 research outputs found
Accurate Sr isotope determination of human bone and tooth samples by LA‐MC‐ICP‐MS: A comment on “Meijer et al., (2019)”
No full textThe in-situ Sr isotope determination of low-Sr bioapatites is challenging and requires monitoring several interferences, among others, Ar-CaPO. In particular, the analysis of human bones and teeth has revealed several pitfalls, which affect the ability to obtain accurate results. In this commentary, I review the data from the paper of Meijer et al. (2019), trying to address some accuracy issues arising, in my opinion, from polyatomic interferences. After a tentative calibration of their data, using the 1/88Sr signal (V−1) as a proxy of the Sr content, the enamel specimens (enamel Ar-CaPO corrected 87Sr/86Sr ratio = 0.7078 ± 0.0032; mean ± 2σ) are closer to the likely local bioavailable Sr (bone Ar-CaPO corrected 87Sr/86Sr ratio = 0.7071 ± 0.0011; mean ± 2σ)
MapIT!: a simple and user-friendly MATLAB script to elaborate elemental distribution images from LA- ICP-MS data
No full textpeer reviewe
The Hf-INATOR: A free data reduction spreadsheet for Lu/Hf isotope analysis
No full textDuring the last decade, the in situ Lu-Hf isotope methodology has been widely used in Earth sciences and the number of laboratories performing Lu-Hf analysis has increased together with dedicated scientific software. However, free and user-friendly software for the Lu-Hf data reduction is currently missing. We present the ‘Hf-INATOR’, a new interactive Excel spreadsheet, simple to use and completely free (compatible with Libreoffice and Openoffice) that performs data reduction of the Lu-Hf analytical outputs and calculates the main parameters of the Lu-Hf systematic, such as the 2σ errors, the εHf(0), the εHf(t), the TDM, the TDMC and the fLu/Hf
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
Produzione attuale di ceramica di tipo mediterraneo protostorico a Barrama (Siliana-Tunisia)
No full textVengono illustrate le produzioni di ceramica domestica d'impasto del centro rurale di Barrama presso Bargou, nel Governatorato tunisino di Siliana. La forma di artigianato familiare, adottata dall’intero villaggio di Barrama come fonte primaria di introiti, è stata documentata in tutte le sue fasi a partire dall'estrazione della materia prima, alla manifattura, rifinitura e cottura dei vasi, sino alla commercializzazione dei prodotti finiti. L'osservazione di alcuni tratti peculiari della produzione fittile offrono stimolanti spunti di riflessione sui possibili sistemi utilizzati nella preistoria
Dynamic Self-Organization and Catalysis: Periodic versus Random Driving Forces
No full textDynamic
self-assembly is an emerging area of research where properly
designed self-assembly elements can be used reversibly to trigger
and control some tasks at the molecular level. The interactions between
decorated nanoparticles, NPs, are experimentally modifiable by a variety
of stimuli that can also vary in time periodically or randomly. In
coarse-grained simulations, we activate a switch, either periodically
or randomly, which assembles–disassembles clusters of NPs.
We then introduce a single catalytic NP(C) covered with catalytic
moieties, C, and leave all remaining NP(R)s decorated with reactive
moieties, R. The catalytic reaction that converts R into products
P depends on the encounter of C and R. Particle-based simulations
are here used to study the catalytic activity and reaction yields
of decorated nanoparticles that aggregate/disaggregate with the application
of time-varying perturbations. Static aggregation is not catalytically
efficient because it traps the catalyst. The application of random
perturbations that vary in time in the form of colored noises improves
the reaction yields and can provide opportunities for more efficient
catalytic activity. The work can also allow us to understand how in
Nature many biological processes are affected or driven by random/noisy
fluctuations of the environment
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
La produzione metallurgica nel sito del Bronzo Medio e Recente di Solarolo-via Ordiere (Ravenna): aspetti della tecnologia e provenienza del rame
Full text linkThis study focuses on the analysis of bronze finds and other objects employed in metallurgical activities from the Middle and Recent Bronze Age site of Solarolo-via Ordiere (Ravenna, Italy) investigated between 2006 and 2019. Materials were found both in Middle and Recent Bronze Age layers, as well as from trenches/survey, and include mostly pins and daggers with typological affinities with other bronzes in Romagna and, more in general, in the central Po plain. Noteworthy is the presence of a golden spiral from the Middle Bronze Age 2 layers. The analysed artefacts also include metal fragments, bronze drops and implements involved in metallurgical activities, such as blowing pipes, tuyères and stone moulds, which imply casting and postcasting activities taking place at the settlement. Lead isotope analyses of 6 bronze samples designate the southern side of the Eastern Alps as preferential provenance of copper, except for one dagger constituted of copper plausibly originated from the ores of the Mitterberg area (Austria). Technological and experimental analyses suggest that the overall metallurgical production at Solarolo was not particularly complex. Objects were often re-used and re-adapted, as consequence of wear and fragmentation. Starting from the significant frequency
of pins, we experimented the reproduction of two types of pins, documented in Northern Italy during these phases, namely “Cattaragna” and “con testa a rotolo” types. The experiments allowed a better understanding of the chaîne opératoire, from the production of stone moulds to the final refining of the surfaces
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