Optimal control of a dengue epidemic model with vaccination

We present a SIR+ASI epidemic model to describe the interaction between human and dengue fever mosquito populations. A control strategy in the form of vaccination, to decrease the number of infected individuals, is used. An optimal control approach is applied in order to find the best way to fight the disease.Comment: This is a preprint of a paper accepted for presentation at ICNAAM 2011, Halkidiki, Greece, 19-25 September 2011, and to appear in AIP Conference Proceedings, volume 138

Modeling and Optimal Control Applied to a Vector Borne Disease

A model with six mutually-exclusive compartments related to Dengue disease is presented. In this model there are three vector control tools: insecticides (larvicide and adulticide) and mechanical control. The problem is studied using an Optimal Control (OC) approach. The human data for the model is based on the Cape Verde Dengue outbreak. Some control measures are simulated and their consequences analyzed

Insecticide control in a Dengue epidemics model

A model for the transmission of dengue disease is presented. It consists of eight mutually-exclusive compartments representing the human and vector dynamics. It also includes a control parameter (insecticide) in order to fight the mosquitoes. The main goal of this work is to investigate the best way to apply the control in order to effectively reduce the number of infected humans and mosquitoes. A case study, using data of the outbreak that occurred in 2009 in Cape Verde, is presented.Comment: Accepted 28/07/2010 in the special session "Numerical Optimization" of the 8th International Conference of Numerical Analysis and Applied Mathematics (ICNAAM 2010), Rhodes, Greece, 19-25 September 201

The Relationships in Marketing: Contribution of a Historical Perspective

This paper presents an historical analysis of relationship marketing. We discuss the roots and the directions of relationship marketing that are considered relevant: their origins, the Industrial Marketing and Purchasing group (IMP) approach to business relationships, the Nordic approach to services relationships and, the managerial and Customer Relationship Management (CRM) approach of relationship marketing. The paper highlights that the boundaries of relationship marketing as defined in contemporary literature have been permeable and elastic. Relationship marketing consists of a fragmented collection of different approaches, partly independent partly overlapping, inspired by different theories, with a multitude of aggregation levels and several units of analysis. We clarify the scope of this domain and we present a number of critical issues that remain unresolved. Is the concept of relationship marketing ubiquitous and can it be applied to every context? Are relationships alike whatever the market considered? Do they describe the same phenomena or are they different phenomena resulting from different contexts? We present a historical analysis of relationships marketing that could contribute to a better understanding of what relationships are in marketing.relationships, business-to-business relationships, relationship marketing, CRM

Brief increases in corticosterone affect morphology, stress responses, and telomere length, but not post-fledging movements, in a wild songbird

Organisms are frequently exposed to challenges during development, such as poor weather and food shortage. Such challenges can initiate the hormonal stress response, which involves secretion of glucocorticoids. Although the hormonal stress response helps organisms deal with challenges, long-term exposure to high levels of glucocorticoids can have morphological, behavioral, and physiological consequences, especially during development. Glucocorticoids are also associated with reduced survival and telomere shortening. To investigate whether brief, acute exposures to glucocorticoids can also produce these phenotypic effects in free-living birds, we exposed wild tree swallow (Tachycineta bicolor) nestlings to a brief exogenous dose of cort once per day for five days and then measured their morphology, baseline and stress-induced corticosterone levels, and telomere length. We also deployed radio tags on a subset of nestlings, which allowed us to determine the age at which tagged nestlings left the nest (fledged) and their pattern of presence and absence at the natal site during the post-breeding period. Corticosterone-treated nestlings had lower mass, higher baseline and stress-induced corticosterone, and reduced telomeres; other metrics of morphology were affected weakly or not at all. Our treatment resulted in no significant effect on survival to fledging, fledge age, or age at first departure from the natal site, and we found no negative effect of corticosterone on inter-annual return rate. These results show that brief acute corticosterone exposure during development can have measurable effects on phenotype in free-living tree swallows. Corticosterone may therefore mediate correlations between rearing environment and phenotype in developing organisms, even in the absence of prolonged stressors.Comment: 35 pages, 4 figures, 1 appendi

Optimization of Dengue Epidemics: a test case with different discretization schemes

The incidence of Dengue epidemiologic disease has grown in recent decades. In this paper an application of optimal control in Dengue epidemics is presented. The mathematical model includes the dynamic of Dengue mosquito, the affected persons, the people's motivation to combat the mosquito and the inherent social cost of the disease, such as cost with ill individuals, educations and sanitary campaigns. The dynamic model presents a set of nonlinear ordinary differential equations. The problem was discretized through Euler and Runge Kutta schemes, and solved using nonlinear optimization packages. The computational results as well as the main conclusions are shown.Comment: Presented at the invited session "Numerical Optimization" of the 7th International Conference of Numerical Analysis and Applied Mathematics (ICNAAM 2009), Rethymno, Crete, Greece, 18-22 September 2009; RepositoriUM, id: http://hdl.handle.net/1822/1083

Science-based restoration monitoring of coastal habitats, Volume Two: Tools for monitoring coastal habitats

Healthy coastal habitats are not only important ecologically; they also support healthy coastal communities and improve the quality of people’s lives. Despite their many benefits and values, coastal habitats have been systematically modified, degraded, and destroyed throughout the United States and its protectorates beginning with European colonization in the 1600’s (Dahl 1990). As a result, many coastal habitats around the United States are in desperate need of restoration. The monitoring of restoration projects, the focus of this document, is necessary to ensure that restoration efforts are successful, to further the science, and to increase the efficiency of future restoration efforts

Shared Resources in Industrial Districts: Information, know-how and institutions in the Spanish tile industry

The aim of this paper is to measure the effect of shared resources on individual firm performance. Using the Industrial District as a definition of the interorganizational context, we propose a model that includes a set of factors that are associated with the endowment of external resources, that is, collective information and know-how, and involvement in local institutions. In order to illustrate the theoretical argumentation, we develop an empirical study using a one hundred-firm sample from the Spanish Ceramic Tile industry in order to search for a statistical association between resource variables and performance of the firms. Finally, findings of the paper suggest that in order to increase performance firms must develop a distinct capacity so as to be able to shape and exploit shared or collective resource