1,721,005 research outputs found
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
Laser induced strong-field ionization gas jet tomography
Full text linkWe introduce a novel in-situ strong field ionization tomography approach for characterizing the spatial density distribution of gas jets. We show that for typical intensities in high harmonic generation experiments, the strong field ionization mechanism used in our approach provides an improvement in the resolution close to factor of 2 (resolving about 8 times smaller voxel volume), when compared to linear/single-photon imaging modalities. We find, that while the depth of scan in linear tomography is limited by resolution loss due to the divergence of the driving laser beam, in the proposed approach the depth of focus is localized due to the inherent physical nature of strong-field interaction and discuss implications of these findings. We explore key aspects of the proposed method and compare it with commonly used single- and multi-photon imaging mechanisms. The proposed method will be particularly useful for strong field and attosecond science experiments
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
Development of ultrafast x-ray spectroscopy for the investigation of electron dynamics in semiconductors
No full textDOTTORATOIl processo di generazione di armoniche di ordine elevato (HHG) consente di ottenere sorgenti coerenti di impulsi ultrabrevi nell’estremo ultravioletto (XUV) e nei raggi X soffici (SXR). Recentemente, queste sorgenti sono state utilizzate per diverse applicazioni, dall’imaging alla spettroscopia. In particolare, l’assorbimento transiente nell’XUV permette di combinare risoluzioni temporali estreme, fin nel regime degli attosecondi, con la sensibilità chimica propria di queste lunghezze d’onda. Tuttavia, l’implementazione di questa tecnica è tutt’ora ostacolata dalla complessità dell’apparato sperimentale richiesto e dalla bassa efficienza del processo di HHG. In questa tesi, è stata realizzata una nuova beamline per esperimenti di assorbimento transiente nell’XUV, con lo scopo di superare alcune di queste limitazioni. Un innovativo dispositivo microfluidico è stato impiegato per la generazione di armoniche di ordine elevato, ottenendo una maggiore lunghezza di generazione e un controllo fine sulla densità del gas nel volume di interazione. Sfruttando queste caratteristiche, è stata dimostrata una efficienza comparabile con lo stato dell’arte nella generazione con impulsi ultrabrevi a 800 nm. Inoltre, è stato realizzato un nuovo spettrometro XUV, dal design versatile per adattarsi a diverse esigenze sperimentali. Grazie a questi sviluppi, la beamline permette di eseguire esperimenti in campioni solidi con edge di assorbimento fino a 150 eV, rivolti allo studio dei processi di rilassamento conseguenti all’eccitazione con un impulso di pompa. Sono presentati alcuni risultati sperimentali su campioni di silicio, mentre in futuro la beamline verrà utilizzata per lo studio delle dinamiche elettroniche ultraveloci in materiali avanzati e innovativi.High-order Harmonic Generation (HHG) provides table-top sources of coherent eXtreme UltraViolet (XUV) and Soft-X Ray (SXR) radiation. In the last few years, these sources have been employed for different applications, from imaging to spectroscopy. In particular, ultrafast XUV transient absorption emerged as a promising all-optical spectroscopy technique combining extreme temporal resolution, down to the attosecond regime, with chemical and site selectivity. However, its implementation is still hindered by the technological complexity of the setup and the low conversion efficiency of the HHG process. In this thesis, a
new beamline for ultrafast XUV transient absorption spectroscopy was developed, targeting some of these limitations. The generation of high-order harmonics was performed inside a novel microfluidic platform, granting an extended interaction length with respect to gasjet schemes and fine control over the gas density. An efficiency comparable with state-of-the-art sources below 200 eV was demonstrated, driving the generation with 800 nm pulses. In addition, a new design of flexible XUV spectrometer was implemented. Based on these developments, the new beamline allows performing experiments in solids targeting absorption edges up to 150 eV, studying the relaxation dynamics following charge injection by the pump beam. Preliminary studies were conducted in silicon to benchmark the setup. In the next future, this beamline will be employed for ultrafast XUV transient absorption experiments unveiling the electron dynamics in advanced and innovative materials.DIPARTIMENTO DI FISICA34STAGIRA, SALVATOREFINAZZI, MARC
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
- …
