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Dielectric characterization of binary solvents containing 1,2-dichloroethane and 2-chloroethanol
No full textStatic dielectric constants (epsilon) were determined for the 1,2-dichloroethane (DCE, 1)/2-chloroethanol (CE, 2) binary solvent system at 19 temperatures ranging from -10 to +80 degrees C and in the whole composition range expressed by the mole fraction 0 less than or equal to X(1) less than or equal to 1. The experimental values have been fitted to some equations that could be usefully employed for predictive epsilon calculations. Furthermore, the excess mixing properties (epsilon(E)) have been evaluated in order to point out the presence of solvent-cosolvent adducts in the binary mixtures mentioned above. The values of epsilon(E) have been generally found to be negative and only slightly positive under a few experimental conditions in the CE rich-region, thus giving evidence of a close interaction network probably via hydrogen bonding as well as other interactions of every kind in this solvent system
Sistemi DVB per ricezione handheld
No full textLo scenario atteso dall’introduzione dello standard DVB-H è quello che associa le peculiarità della trasmissione televisiva tradizionale ad elementi specifici dei terminali portatili: mobilità, display e antenne più piccole, copertura in luoghi chiusi e affidabilità della batteria.
L’implementazione del DVB-H consente infatti di ridurre il consumo di potenza del terminale e offre la possibilità di implementare un hand-over seamless. I dati in burst vengono inviati utilizzando una bit-rate significativamente superiore rispetto a quella di un meccanismo tradizionale di streaming, permettendo al ricevitore di essere attivo solo per una frazione di tempo (incremento della durata media della batteria). Inoltre è possibile monitorare le celle adiacenti durante il tempo intercorrente tra due burst successivi, consentendo quindi il passaggio da uno stream all’altro durante gli off-period (seamless handover).
In questo scenario di convergenza tra informatica e telecomunicazioni le emittenti digitali terrestri potranno ritrasmettere il proprio palinsesto su palmari e smartphone; l’apparecchio televisivo si trasformerà quindi in una piattaforma multimediale per lo sviluppo di servizi interattivi, necessariamente indipendente dall’usuale ricezione fissa tramite l’accesso condominiale
The 1,2-dimethoxyethane - water solvent system. Viscokinetic and thermodynamic properties of viscous flow from -10 to 80 °C
No full textKinematic viscosity (v) has been measured for pure 1,2-dimethoxyethane, and for nine of its binary mixtures with water, covering the whole miscibility field, and working at 19 temperatures in the -10 less than or equal to t/degrees C less than or equal to 80 range. The properties investigated have been fitted by some empirical equations of the type v=v(T) and v=v(X(1)). Starting from the experimental viscosities, the thermodynamic parameters (Delta G*, Delta H*, Delta S*) of the viscous flow in these binaries have been obtained by applying the Eyring approach and the standard thermodynamic equations. Furthermore, the excess functions, such as v(E) and Delta G(*E) have been evaluated, showing the existence of quite strong specific interactions between the components, probably via hydrogen bonding and a dipolar network. Experimental variations in the Delta G(*E) quantity with temperature were very useful in order to depict and differentiate the trend in three well defined composition regions, namely M(I), M(II), and M(III), which are probably characterized by different patterns in molecular aggregation between similar and/or non similar species
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
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