1,721,254 research outputs found
Le nuove solitudini nell'era digitale
No full textRecensione a Sherry Turkle, Alone Together. Why We Expect More from Technology and Less from Each Other, Basic Books, New York 2011, trad.it. Insieme ma soli. Perché ci aspettiamo sempre più dalla tecnologia e sempre meno dagli altri, Codice Edizioni, Torino 2012
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
One-pot synthesis of paracetamol via the catalytic reductive carbonylation of nitrobenzene in acetic acid-water as a solvent
No full textParacetamol (N-(4-hydroxyphenyl)acetamide) is a major
ingredient in numerous cold and flu medications due to its
analgesic and antipyretic properties. A number of commercial
methods of paracetamol manufacture are currently in use around
the world. Some commonly used processes start from
chlorobenzene, phenol or nitrobenzene. All the industrial
processes actually used, however, show several drawbacks. For
instance, they are based on multistep routes which sometimes lead to poor overall yield, or show serious effluent problems. The
increasingly stringent environmental legislation has generated a
pressing need for cleaner methods of chemical production, for
instance introducing technologies that reduce or, preferably,
eliminate the generation of waste and avoid the use of toxic and/or hazardous reagents and solvents. According with this, we propose a new approach for the synthesis of paracetamol: by using Pd(II)-diphosphine catalyst precursors, in acetic acid-water as a solvent, we obtain paracetamol with high selectivity from
nitrobenzene in one-pot. At 140 °C and under 45 atm of CO,
nitrobenzene is completely converted to paracetamol and
N-phenylacetamide. The latter is the major by-product of the
reaction (ca. 15 molar %, under such reaction conditions) and also
an interesting target for the pharmaceutical industry. The
selectivity is influenced by several variables such as solvent
composition (H2O-acetic acid ratio), temperature and batch time.
The high temperature and the increase of reaction time favor the
acetylation reaction, which occurs in-situ when p-aminophenol
and aniline readily form from nitrobenzene/CO/H2O. Such
reaction is proposed as a new sustainable alternative to the
synthesis of paracetamol. The absence of chlorobenzene
(chlorine-free chemistry), the use of efficient catalysts and the
possibility to realize a single step process, make this reaction
interesting to be evaluated as a possible alternative to the multisteps industrial processes actually used
One-pot synthesis of paracetamol via the reductive carbonylation of nitrobenzene in acetic acid-water as a solvent
No full textParacetamol (N-(4-hydroxyphenyl)acetamide) is a major ingredient in numerous cold and flu medications due to its analgesic and antipyretic properties. A number of commercial methods of paracetamol manufacture are currently in use around the world. Some commonly used processes start from chlorobenzene, phenol or nitrobenzene. All the industrial processes actually used, however, show several drawbacks. For instance, they are based on multistep routes which sometimes lead to poor overall yield, or show serious effluent problems. The increasingly stringent environmental legislation has generated a pressing need for cleaner methods of chemical production, for instance introducing technologies that reduce or, preferably, eliminate the generation of waste and avoid the use of toxic and/or hazardous reagents and solvents. According with this, we propose a new approach for the synthesis of paracetamol: by using Pd(II)-diphosphine catalyst precursors, in acetic acid-water as a solvent, we obtain paracetamol with high selectivity from nitrobenzene in one-pot. At 140 °C and under 45 atm of CO, p-nitrobenzene is completely converted to paracetamol and N-phenylacetamide. The latter is the major by-product of the reaction (ca. 15 molar %, under such reaction conditions) and also an interesting target for the pharmaceutical industry. The selectivity is influenced by several variables such as solvent composition (H2O-acetic acid ratio), temperature and batch time. The high temperature and the increase of reaction time favor the acetylation reaction, which occurs in-situ when p-aminophenol and aniline readily form from p-nitrobenzene/CO/H2O. Such reaction is proposed as a new sustainable alternative to the synthesis of paracetamol. The absence of chlorobenzene (chlorine-free chemistry), the use of efficient catalysts and the possibility to realize a single step process, make this reaction interesting to be evaluated as a possible alternative to the multi-steps industrial processes actually used
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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