Regional Science Inquiry

Michaela BENEŠOVÁ
Department of Mathematics and Statistics of the Faculty of Science, Masaryk University
Kotlářská 2, 611 37 Brno Czech Republic
misasula@gmail.com

Abstract
The aim of this contribution is to apply methods from optimal control theory to the mathematical modeling of biological pest control. We formulate a pest control strategy for nonlinear Kolmogorov system of n interacting populations by introducing natural enemies as a control function. The sufficient conditions for existence of an optimal feedback control function are based on the fact, that the steady-state solution of the Hamilton-Jacobi-Bellman partial differential equation is a Lyapunov function guaranteeing stability and optimality. We apply those general results to the Lotka-Volterra system with a logistic rate of increase of the prey population and Holling’s second type functional response of the predator population, to illustrate biological control of pest mite in stored grain Acarus siro by predatory mite Cheyletus eruditus.

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Lirandina GOMES
Universidade do Estado da Bahia, Salvador, Brazil

Joaquim RAMOS SILVA*
SOCIUS, School of Economics and Management, Universidade de Lisboa, Portugal
*Corresponding author:
jrsilva@iseg.utl.pt

Abstract
The paper analyzes the experience of Portuguese and Spanish hotel networks in Brazil, specifically on the Northern Coast of Bahia. We look at this process over the period when Brazil was opening up to international tourism corporations through promotion of national and regional policies. The research included surveying hotel representatives from investing countries. Clearly, there is a mighty convergence of interests between hotel groups, civil construction firms, and financial institutions, which appeals strongly to the political powers, particularly at a regional level. We also conclude that countries launching their tourism industry may learn from the experience of first comers with this crisscrossing research approach proving beneficial from various perspectives.

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Valentina G. MAKNI
Assistant Professor, Department of International Economic Relations, Faculty of Management, University of Economics – Varna, Bulgaria
valentina.makni@ue-varna.bg

Abstract

During the last two decades direct selling and its new form known as network marketing (multilevel marketing) illustrate constant growth at a global scale, despite the world economic crisis. According to WFDSA global retail sales in the industry are at amount of 166 billion USD, achieved through 90 million independent salespersons in 2012. In terms of high unemployment and financial instability network marketing deals increasingly as a tool for generating income and employment in the societies. From the 1990s this alternative business model rapidly entered in the lives of people in Central and East European Countries in order to improve their living standards. Direct selling has experienced steady growth in Bulgaria in the last 5 years as the biggest channel of non-store based retailing. The aim of this paper is to provide some evidence for the potential of network marketing in Bulgaria and to explore which factors influence the commission earnings. For this purpose correlation analysis has been used to prove statistical dependencies taking into account the derived L-distribution of representative’s income. In socio-demographic features of Bulgarian, direct sellers have been observed whereat descriptive statistics has been conducted.

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