1,720,978 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
The productivity of science & engineering PhD students hired from supervisors’ networks
No full textWe compare the scientific productivity of PhD students who are hired from a fine-grained set of mutually exclusive affiliation types: a PhD supervisor's affiliation, an external affiliation from which the supervisor derives her coauthors, and an external affiliation with which the supervisor has no coauthorship ties. Using a novel dataset of science and engineering PhD students who graduated from two major Swiss universities, we find that the most productive PhD category is the one made of students who are affiliated with universities other than their supervisors’ affiliation, but from which the PhD supervisors derive their coauthors. This result suggests an inverted U-shaped relationship between PhD students’ productivity and the social distance from their supervisors. Additionally, we find evidence consistent with the role of supervisors’ coauthor networks in resolving information asymmetries regarding PhD talent.CEM
Micro venture capital
Full text linkRecently, the venture capital (VC) industry has experienced the entry of several new capital providers. Using US data on investors and their portfolio startups from 2000 to 2022, we document the emergence of a new type of investors: the micro VC. Our analysis reveals that micro Vencture Capitalists (VCs) have an idiosyncratic investment strategy, which differs from traditional VCs. Compared with these investors, micro VCs invest in riskier startups, that is, early-stage ventures initiated by less experienced founders; yet, micro VCs are less likely to syndicate, stage their investments, and replace the startup founders. Additionally, startups funded by micro VCs are less likely to experience successful exits than those backed by traditional VCs. These results can be traced to a mix of smaller capital endowments, less sophisticated limited partners, and lesser human capital of which micro VCs dispose, and that may induce them to spread their thin capital across many investments to maximize returns. Our analysis also uncovers important differences in the strategies pursued by micro VCs and business angels.Managerial SummaryThe VC industry is increasingly populated by a variety of investors with disparate characteristics and objectives. One such type of investors is represented by the so-called micro VC firms. These are VC firms that manage funds typically below $50 million and focused primarily on investing in founder-led startups. We leverage comprehensive VC data in the United States to answer three questions: (1) Who leads micro VC firms? (2) How do micro VC firms invest? (3) How do startups backed by micro VC perform? We find that micro VC firms are often led by relatively inexperienced entrepreneurs with little VC experience, and these firms are supported by less sophisticated limited partners. Although micro VC firms invest in riskier startups, they are less engaged in syndication and investment staging than traditional VC firms. Finally, micro VC-backed startups have a lower probability of successful exit as compared with those backed by traditional VC firms. Collectively, our results suggest that micro VCs differ from traditional VCs beyond being "micro.
The non-xanthine heterocyclic compound SCH 58261 is a new potent and selective A2a adenosine receptor antagonist
No full textWe have characterized the in vitro pharmacological profile of the new potent and selective A2a adenosine receptor antagonist SCH 58261 [7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2, 4-triazolo[1,5-c]pyrimidine]. In binding studies on rat and bovine brain tissues, SCH 58261 showed affinity in the low nanomolar range at A2a adenosine striatal receptors and good A2a adenosine vs. A1 adenosine selectivity (about 50- to 100-fold in rat and bovine brain, respectively). SCH 58261 did not show affinity for either the A3 adenosine receptor or other receptors at concentrations up to 1 microM. Saturation experiments on rat A1 and A2a adenosine receptors indicated the competitive nature of the antagonism. SCH 58261 antagonized competitively the effects induced by the A2a adenosine-selective agonist CGS 21680 (2-[4-(2-carboxyethyl)-phenethyl-amino]-5'-N- ethylcarboxamidoadenosine) in two functional assays, such as inhibition of rabbit platelet aggregation and porcine coronary artery relaxation. Specifically, the compound showed pA2 values of 7.9 and 9.5, respectively. SCH 58261 (300 nM) failed to antagonize 5'-N-ethylcarboxamidoadenosine-induced vasorelaxation in the isolated guinea pig aorta, a response mediated by A2b adenosine receptors. Likewise, at the same concentration, the compound weakly inhibited the A1 adenosine-mediated negative chronotropic effect induced by 2-chloro-N6-cyclopentyladenosine in the isolated rat atria. These data show that SCH 58261 is a potent and selective non-xanthine A2a adenosine antagonist which has competitive properties in biological responses mediated by this receptor subtype. The compound is of interest for investigating the biological role of A2a adenosine receptors and deserves further attention to clarify the therapeutic potential of A2a antagonists
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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