1,721,026 research outputs found
Poly(Glycidyl Methacrylate): A Highly Versatile Polymeric Building Block for Post-Polymerization Modifications
No full textThe treatment of poly(glycidyl methacrylate) with nucleophilic agents yielded new linear homo/co-polymers. The materials obtained have different physicochemical properties depending upon the nucleophiles utilized and thus, by this way, water soluble polymers are easily accessible. This approach is also very convenient for the synthesis of amphiphilic block copolymers. Additional chemical modifications can further transform the obtained polymers after the post-polymerization treatment. Starting from RAFT pre-synthesized/pre-functionalized polymers, the described procedures allow us to obtain a wide variety of chemically diverse materials characterized by controlled structure and specific functions
A polypurine sequence that acts as a 5' mRNA stabilizer in Mycobacterium tuberulosis and Mycobacterium smegmatis
No full textDNA replication in phage P4: Characterization of replicon II
No full textThe genetic element P4 propagates in its host Escherichia coli both as a satellite phage and as a plasmid. Two partially overlapping replicons coexist, namely replicon I and replicon II. The former is composed of two sites, ori1 and crr, and depends on P4 (alpha) gene product for replication. The P4 (alpha) protein has primase and helicase activities, and binds specifically to both ori1 and crr. Replicon II is composed of two sites, ori2 and crr, and its replication also depends on P4 (alpha) primase and helicase activities. In replicon II, the (alpha) protein binds only crr. Here we show that for replicon II the relative orientation of ori2 and crr is essential for replication to occur. Furthermore we delimit ori2 to a 22 bp region (6234-6255), internal to the (alpha) gene, sufficient for replicon II replication. We mutagenized this region and identified two mutants, which carry one and two base substitutions, respectively, that prevent replicon II replication. In electrophoretic mobility shift experiments of ori2, ori1, and crr DNA fragments with E. coli extracts, ori2 was not shifted, whereas both ori1 and crr were specifically bound, suggesting that other host protein(s), beside P4 (alpha), are able to bind to these cis essential regions. Apparently, no binding to ori2 could be identified, thus suggesting that neither (alpha) nor other bacterial proteins specifically bind to this region
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
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