1,723,755 research outputs found
Optimal dividend strategies for a catastrophe insurer
Get PDFIn this paper we study the problem of optimally paying out dividends
from an insurance portfolio, when the criterion is to maximize the expected
discounted dividends over the lifetime of the company and the portfolio
contains claims due to natural catastrophes, modelled by a shot-noise Cox claim
number process. The optimal value function of the resulting two-dimensional
stochastic control problem is shown to be the smallest viscosity supersolution of
a corresponding Hamilton-Jacobi-Bellman equation, and we prove that it can
be uniformly approximated through a discretization of the space of the free
surplus of the portfolio and the current claim intensity level. We implement
the resulting numerical scheme to identify optimal dividend strategies for such
a natural catastrophe insurer, and it is shown that the nature of the barrier and
band strategies known from the classical models with constant Poisson claim
intensity carry over in a certain way to this more general situation, leading
to action and non-action regions for the dividend payments as a function of
the current surplus and intensity level. We also discuss some interpretations in
terms of upward potential for shareholders when including a catastrophe sector
in the portfolio.Este artículo se encuentra originalmente publicado en Frontiers of Mathematical Finance (e-
ISSN:2769-6715
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6715.pdf (Publisher’s version ) (Open Access
Linked collectors and determiners for: ERBG AVH data.
No full textNatural history specimen data linked to collectors and determiners held within, "ERBG AVH data". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/bfbac936-6715-4f50-9b18-175bffb85025">https://bionomia.net/dataset/bfbac936-6715-4f50-9b18-175bffb85025</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/bfbac936-6715-4f50-9b18-175bffb85025">https://gbif.org/dataset/bfbac936-6715-4f50-9b18-175bffb85025</a>. Formatted as a Frictionless Data package
Growth and acid production profile of Streptococcus mutans 6715 in the presence of tannic acid.
No full textSalvadora persica (Miswak) and certain related Nigerian chewing stick plants are used as a toothbrush substitute for oral hygiene. One of the proposed active substances in these chewing sticks is tannic acid, which has been shown to possess antibacterial and antifungal properties. This study was carried out to investigate the effect of tannic acid (TA) on the growth and acid production of Streptococcus mutans 6715. Various concentrations of TA prepared with trypticase soy broth were inoculated with Streptococcus mutans 6715 and incubated at 37oC. Growth was monitored by OD measured at specific intervals. In acid production experiment, cells of the bacterium were used as non-growing cell suspension in a combined buffer solution of 40 mM NaHCO3 and 6 mM K2HPO4 to which various concentrations of TA were added. Data showed that TA was bacteriostatic at concentrations of 10, 100, 200 and 300 mg/ml and bactericidal at 500 mg/ml. However, acid production of Streptococcus mutans 6715 was not affected by presence of TA. Growth inhibition of Streptococcus mutans 6715 demonstrated by this study suggests that tannic acid may play an important role in restricting plaque accumulation and hence dental caries.King Saud Universit
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
Extracellular Dextran Hydrolase from Streptococcus mutans Strain 6715
No full text Streptococcus mutans strain 6715 was shown to produce an extracellular dextranase with endohydrolytic α-(1→6)-glucan-6-glucanohydrolase activity. The enzyme degraded soluble polymers produced by some oral streptococci but did not disperse the streptococcal plaques tested. Enzyme levels in the culture supernatant were elevated in sucrose and sucrose plus glucose cultures but remained at basal levels in glucose and dextran plus glucose cultures. </jats:p
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
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