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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
Ruin probability estimation for an extended Cramer-Lundberg model with nonconstant jump intensity
No full textLAUREA MAGISTRALEQuesta tesi è incentrata sull'analisi della probabilità di rovina di una compagnia assicurativa attraverso il modello di rischio di Cramér-Lundberg. In particolare, l'idea è di utilizzare come base il processo di surplus introdotto da Cramér, e di sostituire al processo di Poisson che modellizza l'arrivo dei claims, un processo per cui l'intensità dei salti non è più costante nel tempo e per cui l'arrivo di un claim possa causare l'arrivo di altri. Per questo motivo vengono utilizzati quelli che vengono chiamati branching processes, processi che normalmente descrivono l'evoluzione di una popolazione nel tempo e che in questo caso vengono usati per simulare l'arrivo dei claims nel caso siano o meno causati da altri claims.
Il primo capitolo è l'introduzione, la quale colloca nella letteratura il modello di Cramér-Lundberg ed i suoi modelli derivati, spiega l'obiettivo del lavoro, con un focus particolare sulla simulazione delle probabilità di rovina nel caso in cui la teoria delle grandi deviazioni venga o meno utilizzata.
Il secondo capitolo è un'analisi di un particolare branching process: il processo di Hawkes, il quale è caratterizzato da un'intensità stocastica che rende possibile un comportamento "auto-alimentante", ossia che ogni singolo arrivo di un claim ne può causare altri. Il processo viene definito nelle sue due classiche rappresentazioni, viene brevemente analizzata la stazionarità ed infine vengono descritti i principali metodi di simulazione, con particolare riferimento all'algoritmo introdotto da Dassios e Zhao che verrà poi utilizzato nel quinto capitolo.
In modo simile al precedente, il terzo capitolo espone le caratteristiche principali del modello di Galton-Watson, il più semplice branching process esistente in letteratura, con particolare riferimento all'estinzione del processo. Inoltre vengono introdotti il modello di Galton-Watson con immigrazione e il random indexed branching process, i quali verranno utilizzati nelle simulazioni del sesto capitolo.
Il quarto capitolo espone il modello di rischio di Cramér-Lundberg definendo le possibili distribuzioni dei processi che lo compongono. Viene effettuata un'analisi dei premi nel caso in cui il modello sia basato su un compound Hawkes process ed infine espone tutti i possibili modi con cui può essere determinata la probabilità di rovina della compagnia assicurativa.
Il quinto capitolo si basa su un lavoro di Stabile e Torrisi, i quali hanno utilizzato la teoria delle grandi deviazioni per trovare in forma chiusa la probabilità di rovina asintotica. In particolare viene condotta una simulazione della probabilità di rovina in due casi: utilizzando il cambio di misura ottenuto da Stabile e Torrisi, e con la misura di probabilità originale. Questi due metodi vengono quindi confrontati tra loro e con il Cramér-Lundberg upper bound per avere conferma della bontà dei risultati.
Il sesto capitolo, in modo simile al precedente, è volto alla simulazione della probabilità di rovina. In questo caso viene inizialmente utilizzato il modello di Galton-Watson, il quale viene poi migliorato sostituendo ad esso il random indexed branching process. Entrambi i casi sono analizzati sia nel caso in cui ci sia immigrazione, sia nel caso in cui non ci sia.
Nel settimo e ultimo capitolo vengono tratte le conclusioni del lavoro svolto e viene spiegato come potrebbe essere ampliata l'analisi della probabilità di rovina attraverso il modello di Galton-Watson nel caso in cui venga utilizzata la teoria delle grandi deviazioni.This thesis focuses on the analysis of the ruin probability of an insurance company through the Cramér-Lundberg risk model. In particular, the idea is to use as a basis the surplus process introduced by Cramér, and to replace the Poisson process which models the claims arrivals with a process characterized by an intensity of jumps which is no longer constant during time and such that the arrival of a claim may cause the arrival of others. For this reason what are called branching processes are used, which normally describe the evolution of a population over time and that in this case are used to simulate the arrival of claims whether or not they are caused by others.
The first chapter is the introduction, which places the Cramér-Lundberg risk model and its derived models in the literature, explains the objective of the work, with a particular focus on the simulation of the ruin probability in the case in which the theory of large deviations is used or not.
The second chapter is the analysis of a particular branching process: the Hawkes process, which is characterized by a stochastic intensity which makes possible a "self-exciting" behaviour, that is, that every single arrival of claim can cause the arrival of others. The process is defined in its two classical representations, stationarity is briefly analyzed and finally the main simulation methods are described, with particular reference on the algorithm proposed by Dassios and Zhao which will then be used in the fifth chapter.
Similarly to the previous one, the third chapter exposes the main features of the Galton-Watson model, the simplest branching process existing in the literature, with particular reference to the extinction of the process. Furthermore, the Galton-Watson model with immigration and the random indexed branching process are introduced, which will be used in the simulations of the sixth chapter.
The fourth chapter exposes the Cramér-Lundberg risk model by defining the possible distributions of the processes that compose it. An analysis of the premiums is carried out if the model is based on a compound Hawkes process and finally it exposes all the possible ways by which the probability of ruin of the insurance company can be determined.
The fifth chapter is based on a work by Stabile and Torrisi, who used the theory of large deviations to find the asymptotic probability of ruin in closed form. In particular, a simulation of the probability of ruin is carried out in two cases: using the change of measure obtained from Stabile and Torrisi, and with the original probability measure. These two methods are then compared with each other and with the Cramér-Lundberg upper bound to confirm the goodness of the results.
The sixth chapter, similarly to the previous one, is aimed at simulating the probability of ruin. In this case the Galton-Watson model is initially used, which is then improved by replacing it with the random indexed branching process. Both cases are analyzed both in the case in which there is immigration and in the case in which there is not.
In the seventh and last chapter the conclusions of the work carried out are drawn and how the analysis of the probability of ruin could be broadened through the Galton-Watson model in the event that the theory of great deviations is used
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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