Showing papers by "University of the Aegean published in 2011"

Pharmaceutical residues in environmental waters and wastewater: current state of knowledge and future research

Abstract: Pollution from pharmaceuticals in the aquatic environment is now recognized as an environmental concern in many countries. This has led to the creation of an extensive area of research, including among others: their chemical identification and quantification; elucidation of transformation pathways when present in wastewater-treatment plants or in environmental matrices; assessment of their potential biological effects; and development and application of advanced treatment processes for their removal and/or mineralization. Pharmaceuticals are a unique category of pollutants, because of their special characteristics, and their behavior and fate cannot be simulated with other chemical organic contaminants. Over the last decade the scientific community has embraced research in this specific field and the outcome has been immense. This was facilitated by advances in chromatographic techniques and relevant biological assays. Despite this, a number of unanswered questions exist and still there is much room for development and work towards a more solid understanding of the actual consequences of the release of pharmaceuticals in the environment. This review tries to present part of the knowledge that is currently available with regard to the occurrence of pharmaceutical residues in aquatic matrices, the progress made during the last several years on identification of such compounds down to trace levels, and of new, previously unidentified, pharmaceuticals such as illicit drugs, metabolites, and photo-products. It also tries to discuss the main recent findings in respect of the capacity of various treatment technologies to remove these contaminants and to highlight some of the adverse effects that may be related to their ubiquitous existence. Finally, socioeconomic measures that may be able to hinder the introduction of such compounds into the environment are briefly discussed.

A web-based pervasive recommendation system for mobile tourist guides

Abstract: Mobile tourist guides have attracted considerable research interest during the past decade, resulting in numerous standalone and web-based mobile applications. Particular emphasis has been given to personalization of services, typically based on travel recommender systems used to assist tourists in choosing places to visit; these systems address an important aspect of personalization and hence reduce the information burden for the user. However, existing systems fail to exploit information, behaviours, evaluations or ratings of other tourists with similar interests, which would potentially provide ground for the cooperative production of improved tourist content and travel recommendations. In this paper, we extend this notion of travel recommender systems utilizing collaborative filtering techniques while also taking into account contextual information (such as the current user's location, time, weather conditions and places already visited by the user) for deriving improved recommendations in pervasive environments. We also propose the use of wireless sensor network (WSN) installations around tourist sites for enabling precise localization and also providing mobile users convenient and inexpensive means for uploading tourist information and ratings about points of interest (POI) via their mobile devices. We also introduce the concept of `context-aware rating', whereby user ratings uploaded through WSN infrastructures are weighted higher to differentiate among users that rate POIs using the mobile tourist guide application while onsite and others using the Internet away from the POI.

Assessing bee species richness in two Mediterranean communities: importance of habitat type and sampling techniques

Abstract: The decline of bees has raised concerns regarding their conservation and the maintenance of ecosystem services they provide to bee-pollinated wild flowers and crops. Although the Mediterranean region is a hotspot for bee species richness, their status remains poorly studied. There is an urgent need for cost-effective, reliable, and unbiased sampling methods that give good bee species richness estimates. This study aims: (a) to assess bee species richness in two common Mediterranean habitat types: semi-natural scrub (phrygana) and managed olive groves; (b) to compare species richness in those systems to that of other biogeographic regions, and (c) to assess whether six different sampling methods (pan traps, variable and standardized transect walks, observation plots and trap nests), previously tested in other European biogeographic regions, are suitable in Mediterranean communities. Eight study sites, four per habitat type, were selected on the island of Lesvos, Greece. The species richness observed was high compared to other habitat types worldwide for which comparable data exist. Pan traps collected the highest proportion of the total bee species richness across all methods at the scale of a study site. Variable and standardized transect walks detected the highest total richness over all eight study sites. Trap nests and observation plots detected only a limited fraction of the bee species richness. To assess the total bee species richness in bee diversity hotspots, such as the studied habitats, we suggest a combination of transect walks conducted by trained bee collectors and pan trap sampling.

Portable XRF of Archaeological Artifacts: Current Research, Potentials and Limitations

Abstract: Portable X-ray fluorescence (PXRF) serves as an effective, rapid and non-destructive, method for determining the elemental composition of natural and man-made materials, such as ceramic, glaze, glass, obsidian, pigments, paint, and metal artifacts; based on the analysis, the determination of their origin, technological and production issues, comparative studies, and more knowledge in the field of cultural heritage can be aimed at. The wavelengths of the released energy, known as fluorescent X-rays, are detected and measured by spectrograph in the energy dispersive and wavelength manner of detection. Since only the surface of an object is studied, in dimensions that typically range within some millimeters, care needs to be taken that corrosion and decay do not affect the analysis. A world survey of the major applications of PXRF in the analysis of various cultural material types is reported, and the available PXRF setups are described. A review of the results of obsidian characterization and clustering is included, and the advantages, reliability, and limitations are discussed, with particular emphasis on the calibration procedures.

Plagiarism detection using stopword n -grams

Abstract: In this paper a novel method for detecting plagiarized passages in document collections is presented. In contrast to previous work in this field that uses content terms to represent documents, the proposed method is based on a small list of stopwords (i.e., very frequent words). We show that stopword n-grams reveal important information for plagiarism detection since they are able to capture syntactic similarities between suspicious and original documents and they can be used to detect the exact plagiarized passage boundaries. Experimental results on a publicly available corpus demonstrate that the performance of the proposed approach is competitive when compared with the best reported results. More importantly, it achieves significantly better results when dealing with difficult plagiarism cases where the plagiarized passages are highly modified and most of the words or phrases have been replaced with synonyms. © 2011 Wiley Periodicals, Inc.

Development Platforms for Mobile Applications: Status and Trends

Abstract: Mobile devices are increasingly accepted as suitable media for multimedia-rich applications. Software firms have started promoting programming platforms and tools tailored to satisfy the requirements of mobile device users, developers, and resource constraints. This article reviews the main characteristics, relative merits, and shortcomings of the most popular development platform options - specifically, Java ME, .NET Compact Framework, Flash Lite, and Android. It evaluates and compares these options according to various quantitative and qualitative criteria. It aims to serve as a reference point and guide for developers and practitioners in choosing a mobile platform for development on information appliances.

Emergency Fall Incidents Detection in Assisted Living Environments Utilizing Motion, Sound, and Visual Perceptual Components

Abstract: This paper presents the implementation details of a patient status awareness enabling human activity interpretation and emergency detection in cases, where the personal health is threatened like elder falls or patient collapses. The proposed system utilizes video, audio, and motion data captured from the patient's body using appropriate body sensors and the surrounding environment, using overhead cameras and microphone arrays. Appropriate tracking techniques are applied to the visual perceptual component enabling the trajectory tracking of persons, while proper audio data processing and sound directionality analysis in conjunction to motion information and subject's visual location can verify fall and indicate an emergency event. The postfall visual and motion behavior of the subject, which indicates the severity of the fall (e.g., if the person remains unconscious or patient recovers) is performed through a semantic representation of the patient's status, context and rules-based evaluation, and advanced classification. A number of advanced classification techniques have been examined in the framework of this study and their corresponding performance in terms of accuracy and efficiency in detecting an emergency situation has been thoroughly assessed.

A Survey of Pricing Schemes in Wireless Networks

Abstract: The expansion of new technologies is expected to offer economic growth in the wired and wireless technological networking environment, while at the same time, it will offer a wide variety of services and give the possibility for utilizing technologies for the benefit of many subscribers. The Pricing Schemes are designed to offer profitable business to the Wireless Service Providers (WSPs), as well as, to create favorable services for the mobile subscribers and eventually to get charged according to their services usage. In this paper, the Pricing Schemes are classified, based on their ability to adapt to the needs of the WSPs and their subscribers during the entire service period, into Static-based Pricing and Dynamic-based Pricing Schemes. The Pricing Schemes are also analyzed in detail and are further classified according to the factors involved in the price calculation of a service, i.e. the Service Level Agreement (SLA), the subscription type, the negotiation capabilities between WSPs and their subscribers, the network capacity, the available bandwidth and frequency spectrum, the network hops, and the Base Stations (BSs). The affected elements by the pricing network are also discussed, together with the performance evaluation of the presented pricing schemes.

Electronic mobile guides: a survey

Abstract: Mobile tourist guides have been in the spot light for the past decade and are becoming increasingly available in various forms to tourists visiting places. The majority of these mobile tourist guides are to be used via a constant network connection and some as proprietary standalone mobile applications installed on-device. Some are solely navigational assistants using positioning technologies for large cities offering exploratory services and others are used indoors, for example as museum guides. This research paper attempts to categorize these mobile guides using a detailed set of evaluation criteria in order to extract design principles which can be used by application designers and developers.

An analytical method for the simultaneous trace determination of acidic pharmaceuticals and phenolic endocrine disrupting chemicals in wastewater and sewage sludge by gas chromatography-mass spectrometry

Abstract: This article presents an analytical method based on solid-phase extraction (SPE) and gas chromatography coupled with mass spectrometry for the simultaneous determination of the most frequently used acidic pharmaceutical residues, ibuprofen, diclofenac, naproxen and ketoprofen (KFN), and phenolic endocrine disruptors, bisphenol (BPA), triclosan (TCS), nonylphenol, nonylphenol monoethoxylate and nonylphenol diethoxylate, in wastewater and sewage sludge samples. In the first phase of the study, each compound has been characterized individually and afterwards in mixture as a trimethylsilyl derivative in order to identify the characteristic ions (m/z ratio) constituting the mass spectrum and to choose the ions for quantification and confirmation. Subsequently, derivatization was evaluated by testing different variables such as the volume of the derivatization solvent bis(trimethylsilyl)trifluoroacetamide and the effect of each catalyst, pyridine and 1% trimethyl chlorosilane, in the derivatized solution. For the analysis of wastewater samples, two commercial SPE cartridges, C18 and Oasis HLB, were compared for their extraction efficiency of the target compounds. The key parameter of extraction procedure included the effect of pH (2.5, 5.3 and 7) of the loading solution. For solid samples, parameters such as the extracted biomass, the volume of the extraction organic solvent and the effect of matrix interferences in chromatographic analysis were evaluated. By using C18 cartridges as purification procedure and ultrasound sonication, satisfactory mean relative recoveries with BPA-d16 and meclofenamic acid as surrogates were obtained ranging from 91% to 117% for wastewater and 84% to 107% for sewage sludge samples. Nine-point calibration of the standard mixture was performed by linear regression analysis with a correlation coefficient >0.99 for all the tested compounds. Limits of detection for the developed methods were established between 0.3 (KFN) and 14.8 (BPA) ng L−1, and 15.0 (TCS) and 32.9 (BPA) ng g−1 for wastewater and sewage sludge, respectively. Application to real samples of the wastewater treatment plant in Athens, the capital of Greece, demonstrated the presence of all tested compounds in most of the samples.

Willingness to pay for drinking water quality improvement and the influence of social capital

Abstract: Several factors have been identified as determinants of willingness to pay (WTP), including socio-economic and environmental elements. The present article aims to investigate the influence of individual social capital on willingness to pay for environmental goods. In particular, through an empirical study, a multi-dimensional measurement of social capital is conducted and its influence on WTP for water quality improvement is explored. According to the results of the survey it is observed that social capital is a significant explanatory parameter of WTP.

Evaluation of a three-dimensional chemical transport model (PMCAMx) in the European domain during the EUCAARI May 2008 campaign

Abstract: PMCAMx-2008, a detailed three dimensional chemical transport model (CTM), was applied to Europe to simulate the mass concentration and chemical composition of particulate matter (PM) during May 2008 The model includes a state-of-the-art organic aerosol module which is based on the volatility basis set framework treating both primary and secondary organic components to be semivolatile and photochemically reactive The model performance is evaluated against high time resolution aerosol mass spectrometer (AMS) ground and airborne measurements Overall, organic aerosol is predicted to account for 32% of total PM1 at ground level during May 2008, followed by sulfate (30%), crustal material and sea-salt (14%), ammonium (13%), nitrate (7%), and elemental carbon (4%) The model predicts that fresh primary OA (POA) is a small contributor to organic PM concentrations in Europe during late spring, and that oxygenated species (oxidized primary and biogenic secondary) dominate the ambient OA The Mediterranean region is the only area in Europe where sulfate concentrations are predicted to be much higher than the OA, while organic matter is predicted to be the dominant PM1 species in Central and Northern Europe The comparison of the model predictions with the ground measurements in four measurement stations is encouraging The model reproduces more than 94% of the daily averaged data and more than 87% of the hourly data within a factor of 2 for PM1 OA The model tends to predict relatively flat diurnal profiles for PM1 OA in many areas, both rural and urban, in agreement with the available measurements The model performance against the high time resolution airborne measurements at multiple altitudes and locations is as good as its performance against the ground level hourly measurements There is no evidence of missing sources of OA aloft over Europe during this period © Author(s) 2011

Managing Wearable Sensor Data through Cloud Computing

Abstract: Mobile pervasive healthcare technologies can support a wide range of applications and services including patient monitoring and emergency response. At the same time they introduce several challenges, like data storage and management, interoperability and availability of heterogeneous resources, unified and ubiquitous access issues. One potential solution for addressing all aforementioned issues is the introduction of the Cloud Computing concept. Within this context, in this work we have developed and present a wearable -- textile platform based on open hardware and software that collects motion and heartbeat data and stores them wirelessly on an open Cloud infrastructure for monitoring and further processing. The proposed system may be used to promote the independent living of patient and elderly requiring constant surveillance.

Economic Factors And Individual Investor Behavior: The Case Of The Greek Stock Exchange

Abstract: This study undertook an empirical survey of the factors, which mostly influence individual investor behavior in the Greek stock exchange. The results revealed by our sample of 150 respondents confirm that there seems to be a certain degree of correlation between the factors that behavioral finance theory and previous empirical evidence identify as the influencing factors for the average equity investor, and the individual behavior of active investors in the Athens Stock Exchange (ASE) influenced by the overall trends prevailing at the time of the survey in the ASE.

Land-use legacies in the forest structure of silvopastoral oak woodlands in the Eastern Mediterranean

Abstract: Eastern Mediterranean silvopastoral oak wood- lands have been greatly damaged through forest conversion, illegal lumbering, overgrazing, and forest fires. The aim of this study was to assess land-use changes and the legacies that they have imprinted on the forest structure of Quercus macrolepis and accompanying Quercus pubescens and Quercus cerris woodlands on Lesvos Island, Greece. The size structures of adult oak populations were analyzed as indicators of long-term oak regeneration, while short-term recruitment was determined by counting oak seedlings and saplings. The size structure of the adult Q. macrolepis pop- ulation was similar to the inverse J-shaped distribution typ- ical for natural Mediterranean oak forests, indicating continuous recruitment with a constant mortality rate of mature individuals. Seedling and sapling densities were highly variable, but generally low in relation to adult oak densities. Recruitment of oak seedlings and saplings was positively related to determinants such as forest cover, adult oak density and basal area, woody plant richness, and litter cover. Both seedling and sapling occurrence were negatively associated with dung frequency, which suggests that sheep grazing imposes a barrier to oak recruitment. The study outlines a comprehensive land-use transition from the 1950 to 1970s, during which a complex and multifunctional ag- rosilvopastoral land-use system was simplified to an inten- sive grazing system. The discrepancy between the successful long-term regeneration and the less successful short-term recruitment of oaks illustrates that intensified livestock grazing has been a major driver of vegetation change. Grazing impact is likely to interact with increasing drought conditions, which may trigger a negative feedback cycle that undermines the capacity of woodlands to sustain ecosystem services.

A Survey on Cluster-Based Group Key Agreement Protocols for WSNs

Abstract: The scope of this survey is to examine and thoroughly evaluate the cluster-based Group Key Agreement (GKA) protocols for Wireless Sensor Networks (WSNs). Towards this goal, we have grouped the WSNs application environments into two major categories (i.e., infrastructure-based and infrastructureless) and have examined: a) which of the cluster-based Group Key Agreement (GKA) protocols that appear in the literature are applicable to each category, and b) to which degree these protocols will impact the systems' performance and energy consumption. In order to answer these questions we have calculated the complexity of each protocol and the energy cost it will add to the system. The evaluation of all discussed protocols is presented in a generalized way and can therefore serve as a reference point for future evaluations and for the design of new, improved GKA protocols.

Governing desertification in Mediterranean Europe: The challenge of environmental policy integration in multi‐level governance contexts

Abstract: Successfully combating desertification has proven to be a demanding endeavour. Fifteen years since the UNCCD was signed, its implementation record remains poor worldwide and in Mediterranean Europe. Desertification is a complex socio-environmental problem, which requires long-term efforts towards integrating environmental concerns in sectoral and development policies, coordination among sectors, policies, agencies and programmes as well as efficient and effective multilevel collaboration arrangements. It is not accidental that Environmental Policy Integration (EPI) and multi-level governance (MLG) are central notions in the UNCCD neither that it's poor implementation record may partly be due to the difficulties of responding to these challenges. This study explores the role of EPI in combating desertification in MLG contexts. First, it briefly negotiates desertification and the UNCCD emphasizing the EPI and MLG provisions. After presenting the conceptual and methodological framework employed, it offers a broad-brush assessment of the integration of desertification concerns into development policies at the international, EU and Mediterranean member state level and the role of governance and MLG. It concludes that the state of integrating desertification concerns in development policies at all levels is poor and the current mode of governance and MLG are far from the UNCCD ideal of ‘good governance’. The low political priority of desertification, several context-specific factors, the general and sectoral mode of governance and the complexities of contemporary MLG contexts explain this poor integration. Future research directions are suggested to advance the state of knowledge on promoting EPI in MLG contexts and provide policy support for combating desertification. Copyright © 2010 John Wiley & Sons, Ltd.