1,720,991 research outputs found
On the shape of optimal price and advertising strategies arising in innovation diffusion
No full textIn this paper we analyze a nonlinear optimal control model which is a slight modification of the one proposed in De Cesare L. and Di Liddo A. (2000) and describes the penetration of a new product in a market. The model deals with the choice of price and advertising strategies that maximize the profit coming from the product sale. Some theoretical features are investigated in corrispondence with specific choices for price responce functions
A non-linear approach to Kalecki's investment cycle
No full textIn this paper, looking at some new contributions to the Kalecki business cycle theory, we re-examine his 1935 model concerning the gestation period between orders and deliveries of capital goods. The model gives rise to a delay differential equation (DDE) with delay dependent coefficients depending on the time delay. The model has only one equilibrium point. Proved that a unique stability switch exists, we study the emergence of the Hopf bifurcation and the direction, stability and period of the bifurcating periodic solutions. We derive an explicit formula for determining the properties of the Hopf bifurcation by using the first Lyapunov coefficient. To confirm our analytic results, we consider two types of non-linear functions, all consistent with Kalecki's hypotheses: two S-shaped functions and one fractional function. Some comments dealing with the economic implications of our analysis are also included
Valuation of the surrender option in unit-linked life insurance policies in a non-rational behaviour framework
No full textThe variogram of the uniform transform of a random field
No full textIn the Probability Field Simulation algorithm (Froidevaux, 1992), it is required to model the variogram of the uniform transform of a random field. The properties of this last variogram are not well-known in literature. The aim of this paper is to study some properties of the variogram of the uniform transform of a random field Z. Apart from some general results, the uniform transform of a stationary Gaussian process has been considered
A Simulation Technique of a non-Gaussian Spatial Process
No full textRegression-type algorithms for mapping, including kriging, entail a smoothing of the spatial distribution for the estimates and do not offer the flexibility to reproduce patterns of spatial connectivity specific to extreme values. On the other hand, the non-parametric indicator kriging approach allows reproduction of several spatial connectivity functions. The sequential indicator simulation proposed in this paper is viewed as an alternative technique to Gaussian-related models. An application has been presented
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
- …
