1,721,007 research outputs found
Studies on the intron-dependent meristematic expression of the dihydrofolate reductase/thymidylate synthase (DRTS) genes of Arabidopsis thaliana
No full textIn plants, dihydrofolate reductase (DHFR) and thymidylate synthase (TS) constitute a bifunctional enzyme (DRTS) which is essential for the synthesis of DNA precursors in proliferating or endoreduplicating cells. Previous characterizations of the three AtDRTS genes of Arabidopsis thaliana revealed distinctive patterns of expression and a crucial positive control of AtDRTS1 expression in apical meristems by an intragenic region containing the second intron of the gene [1]. In this study we report that the strong meristematic expression of AtDRTS2 is also strictly dependent on the first intron located in the 5’UTR of the gene. However, sequence comparisons of the first intron of AtDRTS2 and the second intron of AtDRTS1 could not detect common regions and a serial mutation analysis of the first AtDRTS2 intron could not identify regulatory elements enabling the meristematic activity of the gene. Nevertheless, the 5’UTR of AtDRTS2 is capable to confer strong meristematic expression when placed downstream of the AtDRS1 promoter suggesting an interchangeability between the two different introns and lack of specificity between promoter and intronic sequences. In addition, we found that the 5’UTR of AtDRTS2 acts at the transcriptional level and can confer meristematic activity also to the promoter of the AtBAM3 gene of A. thaliana, which is strongly and specifically expressed only in leaf tissues. This meristematic activating capacity, however, is not observed with a minimal 35S promoter which indicates that the first intron of AtDRTS2 cannot act autonomously as a promoter by itself but must interplay with additional regulatory regions
Mean Field Approaches for the Homogenization of Elastic Parameters of Lightweight Cemented Soils
No full text
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
Street Architecture: l’infrastruttura come spazio della città e del paesaggio
No full textIn Italy during the ‘60s the construction of public works such as roads and infrastructural networks created fast and safe connections among places, building a new system of relations, superimposed on the landscape, that over time has changed through these new works. Today, with the transformations affecting the transport system, there is an increasing need to talk about the role and sense that infrastructures - old and new –
take on within cities. The sudden collapse of part of the Polcevera Viaduct designed by Riccardo Morandi, that occurred in Genoa in 2018, tragically reminded us that the existing infrastructures need constant overhaul with conscientious replacements of parts and in some cases that it is necessary to give them up if they no longer guarantee safety criteria. The demolition of infrastructures is often seen as the fastest and most
useful solution. However, there are also opinions opposing the demolition tout court that trust in the possibility of reuse and creative transformation for new spaces within the city. This paper analyzes the role of infrastructure within the contemporary city, showing its character as a machine for reading and knowledge of the landscape and its role in the development of studies and experimentations on the construction of perceptual experiences within the architectural project. Infrastructures, and in particular roads and paths, are no longer observed exclusively from a technical point of view but rather as spaces in the city that need new interpretations in order to respond to the growing demand for alternative mobility and related public spaces
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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