University of Piraeus

About: University of Piraeus is a education organization based out in Piraeus, Attiki, Greece. It is known for research contribution in the topics: Context (language use) & Computer science. The organization has 1731 authors who have published 6209 publications receiving 106699 citations.

Benthic communities in the deep Mediterranean Sea: exploring microbial and meiofaunal patterns in slope and basin ecosystems

Abstract: The long-held perception of the deep sea consisting of monotonous slopes and uniform oceanic basins has over the decades given way to the idea of a complex system with wide habitat heterogeneity. Under the prism of a highly diverse environment, a large dataset was used to describe and compare spatial patterns of the dominant small-size components of deep-sea benthos, metazoan meiofauna and microbes, from Mediterranean basins and slopes. A grid of 73 stations sampled at five geographical areas along the central-eastern Mediterranean Basin (central Mediterranean, northern Aegean Sea, Cretan Sea, Libyan Sea, eastern Levantine) spanning over 4 km in depth revealed a high diversity, irrespective of the benthic group or level of taxonomic analysis. A common decreasing bathymetric trend was detected for meiobenthic abundance, major taxa diversity and nematode genera richness, but no differences were found between the two habitats (basin vs slope). In contrast, microbial richness is significantly higher at the basin ecosystem and tends to increase with depth. Multivariate analyses (β- and δ-diversity and ordination analysis) complemented these results and underlined the high within-habitat variability of benthic communities. Meiofaunal communities in particular were found to change gradually and vary more towards the abyss. On the other hand, microbial communities were highly variable, even among samples of the same area, habitat and bathymetry. A significant proportion of the variation of benthic communities and their descriptors was explained by depth and proxies of food availability (sedimentary pigments and organic content), but the combination of predictor variables and the strength of the relationship varied depending on the data set used (based on type of habitat, benthic component, taxonomic level). This, along with the observed high within-habitat variability suggests that other factors, which tend to vary at local scale (hydrodynamics, substrate structure, geochemistry, food quality, etc.), may also relate to the observed benthic patterns. Overall, the results presented here suggest that differences in small-size benthos between the basin and slope habitats are neither strong nor consistent; it appears that within-habitat variability is high, differences among depth ranges are important and further investigation of possible environmental drivers of benthic patterns is needed.

Bank-Level Estimates of Market Power

Abstract: The aim of this study is to provide an empirical methodology for the estimation of market power of individual banks. The new method employs the well-known model of Panzar and Rosse (1987) and proposes its estimation using the local regression technique. Thus, a number of restrictive assumptions regarding the properties of the production function of banks are relaxed, while the method proves successful in providing reasonable estimates of bank-level market power when applied to a large panel of banks of transition countries. The empirical results suggest that many banks in the sample deviate significantly from competitive practices and that market power varies substantially across banks in each country. Country averages of the bank-level results exhibit a very close relationship with standard, industry-level Panzar-Rosse estimates.

Improving the Performance of the Chi-square Control Chart via Runs Rules

Abstract: The most popular multivariate process monitoring and control procedure used in the industry is the chi-square control chart. As with most Shewhart-type control charts, the major disadvantage of the chi-square control chart, is that it only uses the information contained in the most recently inspected sample; as a consequence, it is not very efficient in detecting gradual or small shifts in the process mean vector. During the last decades, the performance improvement of the chi-square control chart has attracted continuous research interest. In this paper we introduce a simple modification of the chi-square control chart which makes use of the notion of runs to improve the sensitivity of the chart in the case of small and moderate process mean vector shifts.

A Process Model Basis for Evolving Hospital Information Systems

Abstract: Hospitals often invest significant resources in the development of large and complex information systems that must be modified and extended to respond to changing requirements and to exploit the capabilities offered by modern technologies. A disciplined approach of managing the evolution of hospital information systems is then required so that to meet the increasing demands for effective and efficient use of scarce resources. This paper takes a process oriented view of the hospital and presents an approach based on hospital process modeling which aims at assessing the current status of computer support within a hospital and at identifying new opportunities for automation. The approach is illustrated by an example taken from a major Greek hospital.

The moderating role of nationality on the satisfaction loyalty link: evidence from the tourism industry

Abstract: The purpose of this study is to investigate the moderating effects of Hofstede's taxonomy of nationalities on the interpersonal and environmental service dimensions that influence satisfaction as well as the link between satisfaction and loyalty. Using exploratory and confirmatory factor analyses and structural equation modelling on a multinational pool of 1544 hotel customers from 10 different countries visiting the island of Crete, the study offers to the literature by confirming that national cultural differences affect perceived satisfaction and loyalty. Moreover, it offers a solid understanding of the role of the service delivery process and its moderating effects on the physical and interactive dimensions of overall satisfaction. However, Hofstede's taxonomy is not fully supported.