1,720,976 research outputs found
Sintesi di nuovi monomeri e oligomeri di acidi peptido nucleici con applicazioni in diagnostica e come potenziali nuovi agenti terapeutici
No full textSynthesis of new monomers and oligomers of modified peptide nucleic acids with diagnostic and potentially therapeutic applications
Peptide nucleic acids (PNA) are DNA mimics in which the sugar phosphate unit is replaced by a pseudo-peptide chain of N-(2-aminoethylglycine) units, each bearing a nucleobase. PNA binds complementary DNA and RNA with high sequence specifity and therefore has potential application as an anti-sense and anti-gene agent, and in genetic diagnostics. In this Ph.D. thesis is described the synthesis of a new class of modified PNA monomers, called hydrazinoPNA (hydPNA), and the study for setting up the appropriate coupling conditions for the dimerization in view of their oligomerization. In these monomers the primary terminal amino group of the aminoethylglycine unit of aegPNA is replaced with a hydrazine moiety. An appropriate choice of two orthogonal protecting groups on the two hydrazine nitrogen atoms makes it possible to drive their coupling with other monomers selectively on one or the other nitrogen atom, thus obtaining two different types of PNA dimers. In this work is also described the synthesis and the preliminary study about the oligomerization of another modified PNA monomers class, called azaPNA, in which the methylene group of the glycine is replaced by an NH group. Metal conjugated PNA monomers and oligomers synthesis and electrochemical studies are also reported. Functionalization of PNA monomers and oligomers with the phtalimido group as elecrochemical probe is also presented such as their electrochemical activity
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
- …
