1,721,175 research outputs found
Stochastic mortality in a complex world: methodologies and applications within the affine diffusion framework
Full text linkIn this Thesis, we address the modelling of stochastic mortality, a key issue for life insurance, pension funds, public policy and fiscal planning. Indeed, the prospective increase of longevity can be an advantage for individuals, but it represents also a relevant social achievement. The stability and consistency of social welfare systems are put in danger worldwide due to the combined phenomenon of the progressive increase in life expectancy, along with the reduction of birth-rates in industrialized Countries. This phenomenon needs to be interpreted in the context of the connected world in which we live, where the multiple networks arising from the globalization, the Internet communication and the global economic development propagate any event in a very short time, making risks more complex.
Due to their very nature, insurance and reinsurance deal with several risks on their balance sheet and, when determining the total risk of a portfolio, they need to establish the rules for aggregating the various risks that compose it. The introduction of market-consistent accounting and risk-based solvency requirements has called for the integration of mortality risk analysis into stochastic valuation models; moreover mortality-linked securities have attracted the interest of capital market investors, who in turn demand transparent tools to price demographic and financial risks in an integrated fashion. Accordingly, a coherent mathematical framework for studying the changes in financial and demographic conditions over time, is suitable. The class of the affine processes has been used in a wide range of applications in financial and actuarial sciences, thanks to its computational tractability and flexibility. For instance, affine processes have been extensively used in modelling the term structure of interest rates, that underpin extensive literatures on the pricing of bonds and interest-rate derivatives and are also at the basis of many of the pricing systems used by the financial industry. Affine models for the force of mortality have been developed in the literature under the assumption of both dependence and independence between mortality and interest rate dynamics.
The core of this Thesis are the affine models and their properties for modelling the evolution of mortality. We propose and discuss two contributions: (i) we fit and compare past mortality trends among different Countries under the mathematical framework of the Feller process; (ii) we design a multiplicative affine model for the future evolution of mortality, by combining two components: the forecast provided by any existing mortality model, representing the deterministic baseline, and an affine driving process that stochastically affects the baseline over the forecasting time horizon. The so structured model not only is affine, thus fitting well our targets, but, when assessing its forecasting performance, it proves to be parsimonious and to provide a more accurate forecast with respect to the baseline. Within such a model, the affine driving factor is tasked with describing the dynamics over time of a measure of the fitting error of the existing mortality model providing the baseline and it is stochastically described by a Cox-Ingersoll-Ross process. For our numerical application, we choose, as the existing mortality model giving the baseline, the Cairns-Blake-Dowd (or M5) model, that is combined with the CIR process describing the stochastic factor affecting the baseline in a multiplicative way. The resulting model is called mCBD. Using the Italian females mortality data, for fixed ages, and implementing the backtesting procedure, over both a static time horizon and fixed-length windows rolling one-year ahead through time, we empirically test the performance of the CBD and the mCBD models in forecasting death rates. On the basis of average measures of forecasting errors and information criteria, we demonstrate that the mCBD model is a parsimonious model providing better results in terms of predictive accuracy than the CBD model and showing a stronger potential to gain accuracy in the long-run when a rolling windows analysis (dynamic approach) is performed.
To conclude, in the Thesis, we explore and test the properties and capabilities of some affine models in fitting and forecasting mortality data both by themselves and as dynamic driving processes multiplying a deterministic baseline. Combining models and mixing techniques prove to give satisfactory results and show a concrete potential to bring the research forward. Our future research is thus oriented to use approaches that combine Monte Carlo simulations and benefit from the synergy between different techniques
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
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
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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