1,721,500 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
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
Destructive and non-destructive tests on columns and cube specimens made with the same concrete mix
Full text linkThis research work presents the results of an experimental campaign performed on column specimens to investigate the capacity of destructive coring test and non-destructive tests to predict the in-place concrete strength. The considered non-destructive tests are Surface Hardness (SH) and Ultrasonic Pulse Velocity (UPV) ones. Using these tests’ results also SonReb method is applied. The peculiarity of this research is that the results of all the performed test on the columns are compared to results obtained from cube specimens made with the same concrete of the columns. The non-destructive predictive methods are performed on both column and cube specimens during the curing of the concrete at different ages, while the destructive coring test on columns specimens at 28th day after casting. A discussion on the comparison between drilled cores’ strength, determined using provisions of different building codes, and cube specimens’ strength is provided. In particular, the code providing the safest concrete strength predictions is identified. Moreover, the influence of different core diameters on the evaluation of in-place concrete strength is analyzed. The variation of core specimens’ strength, depending on the position of test execution along the columns’ height, is also investigated. To assess the in-place concrete strength by non-destructive tests, correlation formulae are calibrated on the bases of cores strength determined according to ACI Code. The prediction ability of these formulae is assessed. Results obtained from SH and UPV tests at different concrete ages are compared to the cube specimen strength at the same ages, and the influence on the measured parameters of different moisture conditions during curing is analyzed. The minimum number of cores to adequately predict the in-place concrete strength by means of SH and UPV methods is also determined. Best predicting SonReb formulations are identified
Detection of X-ray flares from AX J1714.1−3912, the unidentified source near RX J1713.7−3946
Full text linkContext. Molecular clouds are predicted to emit nonthermal X-rays when they are close to particle-accelerating supernova remnants (SNRs), and the hard X-ray source AX J1714.1−3912, near the SNR RX J1713.7−3946, has long been considered a candidate for diffuse nonthermal emission associated with cosmic rays diffusing from the remnant to a closeby molecular cloud.
Aim. We aim at ascertaining the nature of this source by analyzing two dedicated X-ray observations performed with Suzaku and Chandra.
Methods. We extracted images from the data in various energy bands, spectra, and light curves and studied the long-term evolution of the X-ray emission on the basis of the ~4.5 yr time separation between the two observations.
Results. We found that there is no diffuse emission associated with AX J1714.1−3912, which is instead the point-like source CXOU J171343.9−391205. We discovered rapid time variability (timescale ~ 103 s), together with a high intrinsic absorption and a hard nonthermal spectrum (power law with photon index Γ ~ 1.4). We also found that the X-ray flux of the source drops down by 1–2 orders of magnitude on a timescale of a few years.
Conclusions. Our results suggest a possible association between AX J1714.1−3912 and a previously unknown supergiant fast X-ray transient, although further follow-up observations are necessary to prove this association definitively.</jats:p
Targeting epigenetic networks with polypharmacology: a new avenue to tackle cancer.
No full textThe term 'epigenetic' fuses old and new concepts that refer to the modulation of gene expression in cellular heritability, fate, development and programming-reprogramming other than the DNA sequence itself. Epigenetic control of transcription is regulated by enzymes that mediate covalent modifications at gene-regulatory regions and histone proteins around which chromosomal DNA is wound. Many of the enzymes that mediate chromatin epigenetic reactions are deregulated in diseases such as cancer. Thus, small-molecule inhibitors that target chromatin-modifying enzymes represent a novel option for treatment, and DNA methyltransferase and histone deacetylase inhibitors have been approved for cancer treatment. Moreover, other classes of epi-enzymes (MS-275, SAHA) have been demonstrated to have strong disease association, and are currently being targeted for modulation. An epigenetic poly-pharmacological approach targeting multiple chromatin-modifying enzymes may represent a 'smart' option to treat cancer versus the current view on the selective and single pharmacological targeting of epigenetic enzymes
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
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