Publications by authors named "Karatzas G"

A laboratory study was conducted to assess the mobility and mechanisms of chromium release from soils obtained from an area of wide spread geogenic contamination. The agricultural soil sample used in this study was taken from the Schimatari area in Asopos River basin in Greece. In order to refine the isolation of minerals contained in the soil, two types of separation analysis were conducted.

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This paper presents a new integrated GIS modeling method to assess drought vulnerability using multi-criteria analysis. The proposed methodology is an improvement over previous methods since it incorporates both dynamic and static factors that may affect water dynamics and contribute to water scarcity. These factors are: a) precipitation, b) evapotranspiration, c) soil water content, d) soil depth, e) artificial drainage, f) depth to water table, g) runoff accumulation, and h) saltwater intrusion zones.

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Managed Aquifer Recharge (MAR) is becoming an attractive water management option, with more than 223 sites operating in European countries. The quality of the produced water, available for drinking or irrigation processes is strongly depended on the aquifer's hydrogeochemical characteristics and on the MAR system design and operation. The objective of this project is the assessment of the operation efficiency of a MAR system in Cyprus.

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In many Mediterranean islands with limited surface water resources, the growth of agricultural and touristic sectors, which are the main water consumers, highly depends on the sustainable water resources management. This work highlights the crucial role of groundwater footprint (GF) as a tool for the sustainable management of water resources, especially in water scarce islands. The groundwater footprint represents the water budget between inflows and outflows in an aquifer system and is used as an index of the effect of groundwater use in natural resources and environmental flows.

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The present work introduces a national scale flood hazard assessment methodology, using multi-criteria analysis and artificial neural networks (ANNs) techniques in a GIS environment. The proposed methodology was applied in Greece, where flash floods are a relatively frequent phenomenon and it has become more intense over the last decades, causing significant damages in rural and urban sectors. In order the most prone flooding areas to be identified, seven factor-maps (that are directly related to flood generation) were combined in a GIS environment.

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Fertilizers have undoubtedly contributed to the significant increase in yields worldwide and therefore to the considerable improvement of quality of life of man and animals. Today, attention is focussed on the risks imposed by agricultural fertilizers. These effects include the dissolution and transport of excess quantities of fertilizer major- and trace-elements to the groundwater that deteriorate the quality of drinking and irrigation water.

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In recent years, high concentrations of hexavalent chromium [Cr(VI)] have been found in the groundwater system of the Asopos River Basin. This work focuses on a Cr(VI) plume detected in the industrial area of Inofyta, the most important contamination hot spot of the Asopos River Basin. A groundwater flow and Cr(VI) transport model was developed to assess the behaviour of the plume and investigate the location of a suspected nearby source zone.

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A methodology was developed to assess the impact of geogenic origin hexavalent chromium uptake by carrots, and the risk of human consumption of carrots grown in Asopos River basin in Greece. A field scale experiment was conducted with carrots cultivated in treatment plots, with and without compost amendment, in order to assess the impact of carbon in the mobility and uptake of chromium by plants. The results suggested that there is a trend for chromium mobilization and uptake in the surface and the leaves of the carrots cultivated in the treatment plot with the higher carbon addition, but not in the core of the carrots.

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The present study implements a stochastic optimization technique to optimally manage freshwater pumping from coastal aquifers. Our simulations utilize the well-known sharp interface model for saltwater intrusion in coastal aquifers together with its known analytical solution. The objective is to maximize the total volume of freshwater pumped by the wells from the aquifer while, at the same time, protecting the aquifer from saltwater intrusion.

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Soil salinisation is one of the major soil degradation threats occurring in Europe. The effects of salinisation can be observed in numerous vital ecological and non-ecological soil functions. Drivers of salinisation can be detected both in the natural and man-made environment, with climate and the foreseen climate change also playing an important role.

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The recent industrial growth together with the urban expansion and intensive agriculture in Greece has increased groundwater contamination in many regions of the country. In order to design successful remediation strategies and protect public health, it is very important to identify those areas that are most vulnerable to groundwater contamination. In this work, an extensive contamination database from monitoring wells that cover the entire Greek territory during the last decade (2000-2008) was used in order to study the temporal and spatial distribution of groundwater contamination for the most common and serious anionic and cationic trace element pollutants (heavy metals).

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In recent years, high concentrations of hexavalent chromium, Cr(VI), have been observed in the groundwater system of the Asopos River Basin, raising public concern regarding the quality of drinking and irrigation water. The work described herein focuses on the development of a groundwater flow and Cr(VI) transport model using hydrologic, geologic, and water quality data collected from various sources. An important dataset for this goal comprised an extensive time series of Cr(VI) concentrations at various locations that provided an indication of areas of high concentration and also served as model calibration locations.

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Mediterranean semi-arid watersheds are characterized by a climate type with long periods of drought and infrequent but high-intensity rainfalls. These factors lead to the formation of temporary flow tributaries which present flashy hydrographs with response times ranging from minutes to hours and high erosion rates with significant sediment transport. Modeling of suspended sediment concentration in such watersheds is of utmost importance due to flash flood phenomena, during which, large quantities of sediments and pollutants are carried downstream.

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The water flow and the mass transport of agrochemicals in the unsaturated and saturated zone were simulated in the extended alluvial basin of Keritis river in Crete, Greece (a predominantly flat and most productive citrus growing area) using the hydrological model MIKE SHE. This model was set up based on information on land use, geology, soil structure, meteorological data, as well as groundwater level data from pumping wells. Additionally, field measurements of the soil moisture at six different locations from three soil depths (0.

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The purpose of this study was to create a modeling management tool for the simulation of extreme flow events under current and future climatic conditions. This tool is a combination of different components and can be applied in complex hydrogeological river basins, where frequent flood and drought phenomena occur. The first component is the statistical analysis of the available hydro-meteorological data.

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A constructed wetland pilot with Juncus acutus L. plants was investigated for its rhizofiltration efficiency in treating Cr(VI)-contaminated groundwater. Measurements of Cr(VI) and total Cr were performed to estimate the rate of removal.

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A field and laboratory study was conducted to assess the origin and mobility of CrVI in Asopos basin in Greece. Sampling was designed in such way as to capture the spatial variability of chromium occurring in sediments and soils in different lithological units in the area. Physicochemical and geochemical characterization of surface agricultural soils obtained from river terraces and river bed sediments was conducted in order to determine the natural background of chromium.

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Background: Previous clinical studies advocated that probiotics beneficially affect acute radiation-induced diarrhea. These encouraging results were attributed to the restoration of the intestinal flora; however, there is lack of evidence if and how probiotics influence the underlying pathophysiological mechanisms.

Aims: The present study was conducted to investigate the potential supporting role of a synbiotic preparation (combination of pro- and pre-biotics) on experimentally-induced acute radiation diarrhea from the perspective of mucosal inflammation and histological injury.

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Background And Aim: The treatment-of-choice for the optimal management of the dyslipidemia of the metabolic syndrome (MetS) is not clearly defined. We compared the efficacy of 4 drug regimes for the management of this dyslipidemia in a mouse model.

Materials And Methods: A total of 60 C57Bl6 mice comprised the study group.

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Artificial Neural Networks (ANNs) comprise a powerful tool to approximate the complicated behavior and response of physical systems allowing considerable reduction in computation time during time-consuming optimization runs. In this work, a Radial Basis Function Artificial Neural Network (RBFN) is combined with a Differential Evolution (DE) algorithm to solve a water resources management problem, using an optimization procedure. The objective of the optimization scheme is to cover the daily water demand on the coastal aquifer east of the city of Heraklion, Crete, without reducing the subsurface water quality due to seawater intrusion.

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Objectives: Focal adhesion kinase (FAK) and Src, 2 protein tyrosine kinases, have been suggested to regulate several fundamental cellular activities that promote the malignant phenotype in various human tumors, including pancreatic adenocarcinoma. Even though research has already turned in laboratory investigations and clinical trials on the possible use of agents blocking the 2 enzymes in cancer management, the data on the clinical significance of FAK and Src in pancreatic adenocarcinoma are still scarce.

Methods: The FAK and Src protein expression was assessed immunohistochemically in tumor specimens of 65 patients with pancreatic ductal adenocarcinoma and was statistically analyzed in relation to various clinicopathological characteristics, tumor proliferative capacity, and patients' survival.

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Most pancreatic adenocarcinoma patients present with locally advanced or metastatic disease at diagnosis. in this retrospective study the authors evaluated the prognostic significance of the CEA and CA-19.9 serum tumor markers in advanced (unresectable) pancreatic cancer in correlation to other prognostic factors (demographic data, clinical parameters, treatment modality) and survival time using univariate and multivariate methods, in 215 patients with locally advanced (unresectable) or metastatic pancreatic adenocarcinoma.

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Background: Most patients with ductal pancreatic adenocarcinoma are diagnosed with locally advanced (unresectable) or metastatic disease. The aim of this study was to evaluate the prognostic significance of DNA ploidy in relation with established clinical and laboratory variables in such patients.

Methods: Two hundred and twenty six patients were studied retrospectively.

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