1,721,001 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Fisica generale. Meccanica
No full textQuesto eserciziario è rivolto a tutti gli studenti dei corsi diFisica Generale I della laurea triennale. Copre gli argomenti relativialla Meccanica ed in particolare alla Meccanica del punto e allaMeccanica dei sistemi. Eì esclusa invece la parte di Termodinamica,trattata in molti corsi di laurea in maniera separata. L'uso dell'eserciziario non prevede specifiche propedeuticità, senon buone basi di matematica elementare. Lo studente troverà in ognicaso un'estesa sezione di richiami di analisi matematica e digeometria. Inoltre nello svolgimento degli esercizi si è cercato dirichiamare di volta in volta tutti gli strumenti necessari per laricerca della soluzione. Il volume è diviso in due parti che coprono la Dinamica del punto e la Dinamica dei sistemi, ulteriormente suddivisi in capitoli e paragrafi tematici che tendono a seguire il normale flusso e ordinamento dei corsi di laurea. All'interno di ogni capitolo sono proposti diversi esercizi che tentano di coprire il più possibile lo spettro di problemi di Meccanica proponibili a livello dei corsi di Fisica Generale. Abbiamo cercato di compiere uno sforzo di astrazione per sviscerare, a partire da problemi specifici, considerazioni generali per giungere alla definizione di esercizi prototipici. Ad ogni esercizio è associato un indicatore di difficoltà (in una scala da 1 a 3) che permette allo studente di programmare lo studio affrontando eserciziprogressivamente più complessi e di verificare le propriecompetenze. Un paragrafo di riepilogo chiude ogni sezionepresentando esercizi per la cui soluzione è necessario un buoncontrollo di tutti gli strumenti appresi nei paragrafi precedenti
Application of simple models to the study of non equilibrium behavior of inelastic gases
No full textThe dynamics of cooling inelastic gases and the evolution of their velocity fields is addressed by studying a series of simplified models. We first discuss a model of inelastic bard particles, which shows an uncorrelated transient phase (homogeneous cooling state or Haff regime) followed by the emergence of structures in the velocity and density field. Motivated by the linear stability analysis of the Haff regime, which predicts the appearance of density clusters only after the formation of structures in the velocity field, we focus our attention on the velocities of the gas particles. We study the so-called inelastic Maxwell model (IMM), first in a version with infinite connectivity which is the analog of mean-field spin systems. Secondly, we embed the model onto a lattice (in one dimension and two dimension), in order to observe spatial correlations. The mean-field IMM has the advantage that it lends itself to analytical treatment: in one dimension we find an exact asymptotic scaling solution for the probability density function (p.d.f.) of velocities. On the other hand, the lattice version displays typical spatial features of an inelastic gas, e.g., the transient Haff regime followed by the coarsening of structures in the velocity field (shocks in one dimension, vortices and shocks in two dimension), the so-called "return to the Gaussian" phenomenon of the velocity p.d.f. observed in MD simulations, etc. We show that the growth of structures in the lattice model is similar to that of domains in a diffusive field, but presents a short-scale disorder ("internal noise") which is induced by the randomizing effect of collisions. In the lattice model, we can also establish the presence or absence of a mesoscopic scale which is required for a hydrodynamics description of the field evolution
- …
