Showing papers by "University of the Aegean published in 2001"
TL;DR: The overall performance of the three test species, Trifolium pratense, Dactylis glomerata, Plantago lanceolata, was generally highest for plants replanted at their home site and declined with increasing transplanting distance.
Abstract: Geographic variation can lead to the evolution of different local varieties, even in widespread forage plants. We investigated the performance of common forage plants in relation to their genetic diversity and local adaptation at a continental scale using reciprocal transplants at eight field sites across Europe over a 2-year period. The overall performance of the three test species, Trifolium pratense, Dactylis glomerata, Plantago lanceolata, was generally highest for plants replanted at their home site and declined with increasing transplanting distance. The three species differed in the fitness components responsible for the increased overall performance and selection advantage at home sites. In addition to the effects of local adaptation, the majority of measured traits in all three species also showed ecotypic variation. However, no single ecotype of any species was able to outperform the locally adapted strains and do best at all sites, highlighting the importance of maintaining these plant genetic resources.
442 citations
TL;DR: The new EU water framework directive is concisely and critically presented in this article, which institutionalises ecosystem-based objectives and planning processes at the level of the hydrographic basin as the basis for water resource management.
416 citations
TL;DR: The patterns described form a pattern language that can be used as a building block for a systematic view of the software development process involving DSL s.
279 citations
TL;DR: The geochemistry of metals in the harbor and coastal zone of the town of Mytilene (island of Lesvos, Aegean Sea, Greece) was studied after normalization of the metal data to a conservative element and Li was proven to be better suited than Al for such normalization.
184 citations
TL;DR: In this article, a conceptual framework for contemporary multifunctional landscapes is proposed to serve as a basis for the development of an analytical framework for the analysis of the Aegean cultural landscape.
131 citations
TL;DR: The role of natural organic matter (NOM) in chlorination byproduct formation in drinking water is complex, since characteristics of NOM and its behavior during water treatment have not yet been clearly identified.
Abstract: The role of natural organic matter (NOM) in chlorination by-product formation in drinking water is complex, since characteristics of NOM and its behavior during water treatment have not yet been clearly identified. Different approaches have been applied to characterize NOM, with the objective to investigate the mechanisms of its reactions with chlorine. In this way, formation of by-products, which may have adverse health effects on humans, could be minimized. These approaches are summarized in the present review. Efforts to correlate NOM properties with formation of chlorination by-products and conclusions resulting from chlorination of humic and fulvic acid as well as raw water are also discussed.
124 citations
TL;DR: Comparison of four methods including liquid-liquid extraction (LLE), direct aqueous injection (DAI), purge and trap (PAT) and head space (HS) was carried out for determination of volatile organic compounds (VOCs) including trihalomethanes (THMs) in drinking water to show the advantages and disadvantages.
122 citations
TL;DR: This article employed a mixed methodological approach, using questionnaire surveys of individuals and stakeholder focus groups to investigate economic values placed on a wetland surrounding Kalloni Bay on the island of Lesvos, Greece.
100 citations
TL;DR: Adaptive time‐stepping methods based on the Monte Carlo Euler method for weak approximation of Itô stochastic differential equations are developed, with main result new expansions of the computational error, with computable leading‐order term in a posteriori form, based on Stochastic flows and discrete dual backward problems.
Abstract: Adaptive time-stepping methods based on the Monte Carlo Euler method for weak approximation of Ito stochastic differential equations are developed. The main result is new expansions of the computational error, with computable leading-order term in a posteriori form, based on stochastic flows and discrete dual backward problems. The expansions lead to efficient and accurate computation of error estimates. Adaptive algorithms for either stochastic time steps or deterministic time steps are described. Numerical examples illustrate when stochastic and deterministic adaptive time steps are superior to constant time steps and when adaptive stochastic steps are superior to adaptive deterministic steps. Stochastic time steps use Brownian bridges and require more work for a given number of time steps. Deterministic time steps may yield more time steps but require less work; for example, in the limit of vanishing error tolerance, the ratio of the computational error and its computable estimate tends to 1 with negligible additional work to determine the adaptive deterministic time steps. c 2001 John Wiley & Sons, Inc.
92 citations
TL;DR: A combined stated preference (SP) and revealed preference nested logit model of access and main mode choice was developed for the Tel Aviv metropolitan area and represents the mode choice among bus, mass transit, car driver, and car passenger alternatives.
Abstract: A combined stated preference (SP) and revealed preference nested logit model of access and main mode choice was developed for the Tel Aviv metropolitan area. The data used for model estimation include a conventional travel-activity survey and a customized, computerized SP survey. The model incorporates a generic mass transit alternative that represents any possible combination of existing and new technologies, such as heavy rail, enhanced bus, light rail, and suburban rail. The lower level of the nested logit model represents the access choice to the bus or mass transit alternatives, including walk, park and ride, kiss and ride, and bus access alternatives; the upper level represents the mode choice among bus, mass transit, car driver, and car passenger alternatives. Travel time reliability and seat availability are among the attributes of the public transportation alternatives.
82 citations
TL;DR: It was found that only the upper 18 cm of the core collected from the harbour of Mytilene could be reported as metal contaminated, and that the surface layers of coastal sediments assumed 'clean' were enriched in Pb, probably as a result of atmospheric transportation of the metal from the nearby town.
TL;DR: In this article, the authors investigated the buffer allocation problem in short unbalanced production lines consisting of up to six machines that are subject to breakdowns and developed an algorithm based on the sectioning (segmentation) approach to solve the problem.
TL;DR: In this article, the complete symmetry group of a differential equation is extended to integrals of such equations and the algebras of the symmetries of both differential equations and integrals are studied in the context of equations for which the elements are represented by point or contact symmetry.
TL;DR: Chloroform was formed both in the ultrapure water solutions and in the drinking water samples, probably due to the decomposition of 1,1,1-TCP, which is the compound which decomposes fastest followed by 1,3,DCP and 1, 1-DCP.
TL;DR: A heuristic algorithm is proposed to find the optimal buffer allocation (OBA) that minimizes the average work-in-process (WIP) inventory, subject to a minimum required throughput.
TL;DR: In this article, a generalization of John's representation of the identity for the maximal volume position of a convex body inside a polygonal polygon is presented, where K and L are arbitrary smooth convex bodies in ℝ n.
Abstract: We provide a generalization of John's representation of the identity for the maximal volume position of L inside K, where K and L are arbitrary smooth convex bodies in ℝ n . From this representation we obtain Banach–Mazur distance and volume ratio estimates.
TL;DR: The paper adopts an integrated economic–environmental modeling framework and suggests framework guidelines to address the main data issues identified and indicates the broad gaps in current data sets along the four main data dimensions.
Abstract: Integrated analysis of land-use change in support of informed policy-making for sustainable land use at various spatial levels makes heavy requirements for quality data. This paper aims to structure the principal methodological and practical issues of data needs for this task. The data needs for local level analyses of land-use change are given special attention. The paper adopts an integrated economic–environmental modeling framework and suggests the main types of data needed. Four main data dimensions are distinguished: system of spatial reference, system of temporal reference, definitions, and data collection procedures (sources, collection instruments and techniques, recording and retrieval systems, data format, frequency of data collection). To evaluate the suitability of current data sets as well as to guide the collection of new ones, a scheme based on substantive and practical criteria is employed. The former include compatibility, consistency, and reliability of data, while the latter include availability, ease and cost of data collection/retrieval, and transferability of data. The evaluation indicates the broad gaps in current data sets along the four main data dimensions. Based on this evaluation, the paper suggests framework guidelines to address the main data issues identified. RID="" ID="" 1CLAUDE: Coordinating Land Use and Land Cover Data and Analyses in Europe. European Commission Concerted Action project (DG-XII); DAPLARCH: Data Plan Development for Land Use and Land Cover Change Research. Program sponsored by IGBP-IHDP (LUCC and DIS). Street, Durham, North Carolina 27707, USA
TL;DR: This work introduces the notion of digital seals and provides a mechanism for transferring the trust placed by users in companies in the physical world, to the electronic one.
Abstract: Traditional business practice depends on trust relations between the transacting parties. One of the most important aspects of this trust is the quality of the offered services or products. The Web currently constitutes an enabler for electronic commerce, providing a global transaction platform that does not require physical presence. However, transferring trust from the physical world to the electronic one is a process that requires a trust infrastructure. The current infrastructure, based on trusted third parties can be enhanced. We introduce the notion of digital seals and provide a mechanism for transferring the trust placed by users in companies in the physical world, to the electronic one.
01 Jul 2001
TL;DR: In this article, the authors examined the impact of agrotourism on farm characteristics (income, farming practices, investment) and rural population characteristics (age, sex, permanent residence).
Abstract: This study examines the impact of agrotourism on farm characteristics (income, farming practices, investment) and rural population characteristics (age, sex, permanent residence). Results show that even if the agrotourism program appears successful as far as income improvement and willingness to stay in agriculture is involved, most of the agro-tourist holdings in Lesvos operate in the margin of mass tourism with the same ‘customers’ and the same product, without connections with agricultural production, local products promotion, or environmental and cultural landscape conservation. Agrotourism in Lesvos is tourism operated by farmers, but it is not agro-tourism as the later is defined.
TL;DR: In this article, the authors explored the stability of a new Greek Big Five personality measure (TPQue) across different samples in order to explore the suitability of the measure in personnel selection and assessment.
Abstract: The stability and replicability of the Five-Factor model of personality across samples and testing purposes remain a significant issue in personnel selection and assessment. The present study explores the stability of a new Greek Big Five personality measure (TPQue) across different samples in order to explore the suitability of the measure in personnel selection and assessment. The factor structure of the measure across three samples (students, employees, and job applicants) is examined. The results of exploratory and confirmatory factor analyses show that the five-factor structure remains intact for the students’, the applicants’ and the employees’ samples ‐ contrary to previous studies ‐ with all the sub-scales of the personality measure (TPQue) loading on the intended factors. Furthermore, congruence coefficients between the samples justify the stability of the model in the working settings.
TL;DR: Longer exposure seems to increase the inhibition of TBT, DBT, and TPhT during the first hours of exposure, while later the inhibition remains constant, and in the case of MBT, 24 h after exposure, the respiration rate was similar to that of the control biomass.
TL;DR: Two different ways to enhance outcrossing were observed: within the population's flowering period, and within an individual flower's lifespan, which suggests that selection against self pollen was stronger during the first stage of the female phase and weakened as the stylar tissue aged.
TL;DR: It is shown that some well known theorems in topology may not be true without the axiom of choice.
Abstract: We show that some well known theorems in topology may not be true without the axiom of choice.
30 Apr 2001-Journal of Environmental Science and Health Part A-toxic\/hazardous Substances & Environmental Engineering
TL;DR: On a monthly basis, disinfection by-products (DBPs) and volatile organic compounds (VOCs) were measured in raw water and in treated water of four water treatment plants (WTP) as well as from eight representative points of the distribution network of Athens.
Abstract: On a monthly basis, on a one year period, disinfection by-products (DBPs) and volatile organic compounds (VOCs) were measured in raw water and in treated water of four water treatment plants (WTP) as well as from eight representative points of the distribution network of Athens. Liquid-liquid extraction (LLE) method followed by gas chromatography (GC) with electron capture detection (ECD) and mass spectrometry (MS) was used for the determination of the DBPs, while the purge-and-trap (PAT) technique followed by GC-MS was used for the determination of the VOCs. The DBPs that have been studied included trihalomethanes (THMs), haloacetonitriles (HANs), haloketones (HKs), chlorate hydrate (CH) and chloropicrin (CP), while forty one VOCs were also studied including THMs. Chloroform (CM), dichlorobromomethane (DCBM), chlorodibromomethane (CDBM) were the major organic compounds found in all treated water samples. HANs, HKs, CH and CP were detected in treated samples but at lower concentrations.
TL;DR: In this article, it was shown that for compact metric spaces (X, d) the following statements are pairwise equivalent: X is Loeb, d is separable, X has a we ordered dense subset, and X is second countable.
Abstract: It is shown that for compact metric spaces (X, d) the following statements are pairwise equivalent: “X is Loeb”, “X is separable”, “X has a we ordered dense subset”, “X is second countable”, and “X has a dense set G = ∪{Gn : n ∈ ω}, ∣Gn∣ < ω, with limn∞ diam (Gn) = 0”. Further, it is shown that the statement: “Compact metric spaces are weakly Loeb” is not provable in ZF0 , the Zermelo-Fraenkel set theory without the axiom of regularity, and that the countable axiom of choice for families of finite sets CACfin does not imply the statement “Compact metric spaces are separable”.
TL;DR: In this article, an automatic algorithm for monitoring areas of cold cloud tops within mesoscale convective systems that produced floods in Greece is developed based on Meteosat infrared and water vapor images.
Abstract: In this study, an automatic algorithm for monitoring areas of cold cloud tops within mesoscale convective systems that produced floods in Greece is developed. The technique is based on Meteosat infrared and water vapor images. The purpose of the algorithm is the estimation and monitoring of a variety of characteristics associated with propagating convective systems. The algorithm is capable of locating convective regions, tracking them until the point of dissipation, and taking into account the eventual splitting or merging of clouds that takes place during the lifetime of the system. The operability of the algorithm for the two most intense heavy rainfall events that occurred recently in Greece is examined and assessed.
TL;DR: The proposed methodology eliminates thenumber of sampling sites and maximises the information of spatial data from marine ecosystems and could bewidely applied in sampling design concerning coastal pollution problems.
Abstract: The development of a sampling design for optimisingsampling site locations collected from a coastalmarine environment has been the purpose of the presentwork; application of statistical analysis and spatialautocorrelation methods have been carried out. Thedataset included data collected from 34 sampling sitesspaced out in the Strait of Lesbos, Greece, arrangedin a 1×1 NM grid. The coastal shallow ecosystem wassubdivided into three zones, an inner one (7stations), a middle one (16 stations) and an offshorezone (11 stations). The standard error of thechlorophyll-a concentrations in each zone hasbeen used as the criterion for the sampling designoptimisation, resulting into reallocation of thesampling sites into the three zones. The positions ofthe reallocated stations have been assessed byestimation of the spatial heterogeneity and anisotropyof chlorophyll-a concentrations usingvariograms. Study of the variance of the initialdataset of the inner zone taking into account spatialheterogeneity, revealed two different sub-areas andtherefore, the number of the inner stations has beenreassessed. The proposed methodology eliminates thenumber of sampling sites and maximises the informationof spatial data from marine ecosystems. It isdescribed as a step-by-step procedure and could bewidely applied in sampling design concerning coastalpollution problems.
01 Jul 2001
TL;DR: In this article, the authors provide some reference to the dynamics of tourism and environment in the case of the small Greek islands, in view of a sensitive balance between environment, economy and society.
Abstract: Many islands in the world have become tourist destinations on the basis of their natural and cultural heritage. Islands deserve in many respects a special treatment in view of a sensitive balance between environment, economy and society. The dynamics of development/environment opportunities and constraints in the case of small islands are best exemplified in the case of tourism. The growing demand for tourism opens new opportunities, especially for small islands, providing income and employment. At the same time tourism is causing damage to the island environment, culture, monuments, the local population and even the quality of the visitor's experience threatening the basis of tourist development. This paper provides some reference to the dynamics of tourism and environment in the case of the small Greek islands.
03 Sep 2001
TL;DR: The PASSPORT e-service provision and delivery model improves the accessibility of government services and alleviates some business frustrations due to current administrative procedures.
Abstract: Businesses face significant obstacles in interacting with public administrations across Europe. On the other hand, there has recently been a clear trend of governments to deliver electronic services ("e-government") through integrated, customer-oriented mechanisms ("one-stop government"). However, related efforts - both within and outside the European Union - are nationally focused and do not address the needs of businesses entering into cross-border processes. This paper presents a novel architectural, operational and technical framework for providing seamless electronic services to companies that require information and/or transactions with public administrations on cross-border issues. The PASSPORT e-service provision and delivery model improves the accessibility of government services and alleviates some business frustrations due to current administrative procedures.
TL;DR: In this paper, a generalization of the Fordy-Kulish system of matrix nonlinear Schrodinger equations on two-dimensional space-time is presented, which preserves the existence of an infinite set of conservation laws.
Abstract: Using bicomplex formalism we construct generalizations of Fordy-Kulish systems of matrix nonlinear Schrodinger equations on two-dimensional space-time in two respects. Firstly, we obtain corresponding equations in three space-time dimensions. Secondly, a Moyal deformation is applied to the space-time coordinates and the ordinary product of functions replaced by the Moyal product in a suitable way. Both generalizations preserve the existence of an infinite set of conservation laws.