Dimitrios Tsiotas

Introducing a new centrality measure from the transportation network analysis in Greece

This paper introduces a new centrality measure, nominated by the authors as mobility centrality (Cm), which arose during the study of the interregional road network in Greece. The proposed measure is constructed by the use of the anagogic method considering the formula of the kinetic energy of a particle in Physics and adjusting its mathematical analogue to the case of the interregional road network. The new centrality measure is estimated to be useful for the operational analysis of a network (such as the analysis of network flows), since it characterizes as central these vertices that appear to have the greatest tendency to attract or expel network flows. The ability of the proposed centrality measure to illustrate flow tendencies was examined empirically by correlating and regressing mobility centrality to the commuting status of the Greek interregional network and to four of the most common existing centrality measures (betweenness, closeness, straightness and degree centrality) of the available data. The empirical analysis indicated that the proposed centrality measure (Cm) presents sufficient ability to describe the status of the Greek interregional commuting system and it is believed that it is able to describe the inner potential that produces flows in a network.

Decomposing multilayer transportation networks using complex network analysis: a case study for the Greek aviation network

This article studies the topology of the multiplex Greek Aviation Network (GAN) consisting of layers representing networks of the aviation companies that operate in the regional Greek aviation market, by using complex network analysis and empirical techniques. The purpose of the study is to decode the strategic plans of the aviation companies constituting multiplex network’s layers and to evaluate which layer contributes more in the composition of the overlaid GAN. Secondarily, this paper evaluates the operational utility of a new centrality measure, named mobility centrality, regarding its ability to quantify the potential that a node attribute induces to the topology of the network. Under an overall assessment, this article advances multilayer network analysis by applying a multivariate regression technique for evaluating in common the participation of each layer to the formation of the overlaid network and it provides insights on transportation management and policy.

The contribution of ANN’s simple perceptron pattern to inequalities measurement in Regional Science

The present paper presents a synthetic approach to the XOR operation structure combining the cognitive matter of different fields of scientific study in order to elect further utility of this operation for the inequalities measurement in Regional Science. The observation of structural similarities, between the simple perceptron pattern, in artificial neural networks (ANN), and an XOR binary logic gate, in Digital Electronics Theory authorizes these two models to be considered identical for inequalities detection, under the presumption that both of them can provide a solution for the XOR problem. The solution of the XOR problem for a simple perceptron pattern introduces a new inequalities index, aroused as a generalization of the XOR problem’s solution for the ANN simple perceptron model. The new index appears to operate satisfactorily in Regional Science’s inequalities research, providing a significant similar behavior in comparison with the Theil index and performing better in cases that the Theil index calculation presupposes transformation treatment.

Analyzing the Location Decisions of Agro-Industrial Investments in Greece

This article examines empirically the factors determining the agro-industrial investments in Greece and their impact on tourism development. Firstly, the determinants influencing the spatial configuration, the socioeconomic forces and the political framework of the agro-industrial investments in Greece are examined theoretically, according to the literature considered by Regional Science. At next, a multi-ordinal regression analysis is applied on the determinants elected theoretically, utilizing statistical data from Greece that describe the period 2004-2008. The results of the analysis are interpreted under the regional developmental perspective, constituting an indirect evaluation of the Greek Developmental Laws 3299/04 and 3522/06, applied by the Government to orientate the developmental dynamics of the agro-industry in Greece. Finally, a further analysis is applied comparing the agro-industrial investments with the tourism dynamics in Greece, indicating a field of policy implementation.

The Evolution and Spatial Dynamics of Coastal Cities in Greece

The procedure of human evolution has been always connected with the concepts of space and time. Communities that existed in the same chronological period in different geographic locations, such as communities that existed in the same geographic location at different eras, present various patterns of development. This statement indicates, on one hand, the significance of the spatial parameter to the Economic and Regional Analysis and, on the other hand, the directions that the Economic Research should be oriented to, in order to provide more complete outcomes. From the amount of spatial attributes that a geographic location may possess, the present article deals with the coastal one. Coastal areas have played diachronically a leading role to the development of human civilization, ought to their geographical characteristics, focused on to the seaside location , which provides many transportation advantages, such as development of ports (Li, 2003), commodity (trade development) (Cori, 1999) and also environmental advantages, such as mild climate and natural beauty (Yeung, 2001). The purpose of this chapter is to study the evolution and the spatial dynamics of coastal cities, through a spatial, statistical and regional analytic approach, in order to recognize and to interpret the patterns that describe this evolution, under the regional economic and policy perspective.

Ultrasonographic diagnosis of carpal tunnel syndrome: introducing a new approach

IntroductionCTS, the most common nerve entrapment syndrome of the upper limb, is being diagnosed by clinical criteria, in most cases supported by the electrodiagnosis method, which appears limits regarding its sensitivity and specificity and suggests an intervening and expensive technique. The purpose of this study was to contribute to establishing U/S examination as a method with at least of the same accuracy with electrodiagnosis.Material and methodA sample of 60 healthy individuals and 30 patients suffering from CTS was scanned. The diagnosis was conducted by both clinical and electrodiagnostic criteria, or by clinical criteria supported by postsurgical outcome.MethodIn order to improve the accuracy of measurements, the anteroposterior to transverse diameter of the median nerve inside the canal and in its entrance was scanned and compared, by sonography. The examination conducted three times for each dimension, and the mean value per individual was calculated.ResultsThe mean ratios for the 60 healthy wrists was found to range within the interval 0.49–0.88 (presenting a mean value of 0.66), and the corresponding for the 30 suffering from CTS wrists was within the interval 1.12–1.59 (with a mean value of 1.39).ConclusionThe statistical analysis of the examination results clearly demonstrates that the interval of ratios over the value 1.07 can be considered completely safe to diagnose that someone is suffering from CTS. In correspondence, a U/S measurement of ratios in the area up to 0.79 is completely safe to opine that this wrist refers to a healthy individual. The intermediate range of ratios 0.79–1.0 suggests a grey zone, which, by the rational of this study, does not include discrete CTS or healthy cases. This “gap” may describe subclinical or mild cases of CTS which were not been taken under consideration and for which there is no rational to interfere surgically. In the everyday’s practice clinical point of view, the grey zone cases are considered healthy.

The imprint of tourism on the topology of maritime networks: evidence from Greece

Abstract This paper examines the tourism information enclosed in the topology of the Greek maritime network (GMN) referring to a coastal country with many islands and a tourism orientation in its economy. The rationale of the analysis concerns the symbiotic relationship between tourism and transportation, which under the network paradigm defines the triplet of tourism–transportation network–economy, suggesting the criterion of the grouping of the available variables. The results verify the interacting role between these components for economic development, illustrate a gravity structure in the GMN, and validate the utility of network analysis in socioeconomic research. Overall, this article introduces network topology as a new variable in the study of tourism and transportation systems.