1,721,030 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
Structure and dynamics of flour by solid state NMR: effects of hydration and wheat aging
No full textThe effects of accelerated aging of wheat seeds on structural and dynamic properties of dry and hydrated (ca 10 wt % H2O) flour at a molecular level were investigated by several high and low resolution solid-state NMR techniques. Identification and characterization of domains with different mobility was performed by 13C direct excitation (DE) and cross-polarization (CP) magic angle spinning (MAS), as well as by 1H static and MAS experiments. 1H spin-lattice relaxation times (T1 and T1F) measurements were carried out to investigate molecular motions in different frequency ranges. Experimental data show that the main components of flour (starch and gluten proteins) are in a glassy phase, whereas the mobile fraction is constituted by lipids and, in hydrated samples, absorbed water. A lower proportion of rigid domains, as well as an increased dynamics of all flour components are observed after both seeds aging and flour hydration. Linear average dimensions between 20 and 200 Å are estimated for water domains in hydrated samples
Solid-state NMR studies of pharmaceutical systems
No full textHigh- and low-resolution solid-state nuclear magnetic resonance (SSNMR) applications to the study of pharmaceuticals are reviewed. Examples are shown involving the use of mono- and bidimensional SSNMR techniques based on different nuclear interactions and the measurement of several nuclear parameters, such as chemical shifts, line widths, and relaxation times (T1, T2, T1r). The systems investi- gated include pure active pharmaceutical ingredients (APIs), substances used as drug excipients, and solid dispersions formed by APIs and excipients, up to final drug formulations. The most important aspects treated concern structural, dynamic, and morphological properties, and, in particular, identification, characterization, and quan- titation of polymorphs and related forms, conformational and crystalline packing behavior, amorphous phase properties and stability, effects of drug processing, molecular motions, API-excipient and excipient-excipient chemical and physical inter- actions, and phase mixing in heterophasic systems
Biological effects on DNA and on ultrastructure of fetal white blood cells (WBC) from mothers monitored by continuous ultrasounds
No full textIn order to investigate biological effects of ultrasounds on blood cell DNA, a biochemical study was undertaken at the ultrastructural and molecular level on lymphocytes from babies whose delivery was directed through ultrasound monitorage and babies whose mother had undergone ultrasound monitorage 48 hours before delivery. Our preliminary results show that the ultrasounds currently employed in diagnostics and monitorage can induce upon DNA in vivo reversible damages, as mentioned before, while ultrastructural alterations are still detectable 48 hours after sonicatio
Cotton fibers encapsulated with homo- and block copolymers: Synthesis by the atom transfer radical polymerization grafting-from technique and solid-state NMR dynamic investigations
No full textCotton fibers were modified by surface-initiated atom transfer radical polymerization of ethyl acrylate (EA) followed by copolymerization with styrene. Either ethyl 2-bromopropionate as a sacrificial free initiator or Cu(II) as a deactivator was used to optimize the EA grafting yield and to preserve the livingness of the chain ends for the subsequent growth of a poly(styrene) (PSty) block from the poly(ethyl acrylate) (PEA) grafts. The polymer-encapsulated cotton fibers were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and solid-state NMR (high-resolution C-13 cross-polarization magic angle spinning, H-1 spin-lattice relaxation times, and H-1 free induction decay analysis NMR). The latter allowed the detection of the dynamic modifications associated with the presence of homo- and block copolymer grafts. In particular, the results of the DSC and NMR investigations suggest a heterogeneous morphology of the g-PEA-b-PSty grafted skin, which could be described as an inner layer of g-PEA sandwiched between the semicrystalline cellulose of the core fiber and the high glass transition temperature PSty of the covalently linked outer layer. Such morphology results in a reduced molecular mobility of the PEA chains
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