Showing papers by "University of the Aegean published in 2007"

The Geographic Distribution of Big Five Personality Traits Patterns and Profiles of Human Self-Description Across 56 Nations

Abstract: The Big Five Inventory (BFI) is a self-report measure designed to assess the high-order personality traits of Extraversion, Agreeableness, Conscientiousness, Neuroticism, and Openness. As part of the International Sexuality Description Project, the BFI was translated from English into 28 languages and administered to 17,837 individuals from 56 nations. The resulting cross-cultural data set was used to address three main questions: Does the factor structure of the English BFI fully replicate across cultures? How valid are the BFI trait profiles of individual nations? And how are personality traits distributed throughout the world? The five-dimensional structure was robust across major regions of the world. Trait levels were related in predictable ways to self-esteem, sociosexuality, and national personality profiles. People from the geographic regions of South America and East Asia were significantly different in openness from those inhabiting other world regions. The discussion focuses on limitations of t...

Occurrence patterns of pharmaceuticals in water and wastewater environments

Abstract: The occurrence of pharmaceuticals and their metabolites and transformation products in the environment is becoming a matter of concern, because these compounds, which may have adverse effects on living organisms, are extensively and increasingly used in human and veterinary medicine and are released continuously into the environment. A variety of pharmaceuticals have been detected in many environmental samples worldwide. Their occurrence has been reported in sewage-treatment-plant effluents, surface water, seawater, groundwater, soil, sediment and fish. This paper provides an overview of recent scientific research on the sources, occurrence, and fate of pharmaceuticals in water and wastewater.

Land abandonment and slope gradient as key factors of soil erosion in Mediterranean terraced lands

Abstract: An important land use change recorded in the Mediterranean basin comprises the abandonment of agricultural lands due to economic and social changes, which is followed by significant impacts on soil erosion. Observed land abandonment may have positive or negative impacts on soil protection from erosion because fundamental ecosystem processes are influenced by changes in agricultural practices and soil resources management. Olive groves comprise a typical example of traditional, extensive cultivation, which is abandoned. The olive groves are spread on marginal areas and located mainly on sloping terraced lands with low productivity soils. A field study was conducted for two years in order to monitor the change through time of natural resources such as soil and vegetation, following land abandonment, considering three land uses, cultivation, short-time abandonment and long-time abandonment. Experimental plots were established on two specific slope gradients so that results could be comparable. The study was based on the determination of water erosivity measuring parameters such as rainfall characteristics, sediment losses and water runoff volume, and on the determination of soil erodibility, measuring parameters related to vegetation, soil, slope profile description and drystone terraces. Results show that abandonment of traditional extensive cultivation in the Mediterranean basin has different impacts on soil sediment losses according to slope gradient. When slope gradient is steep (25%), soil erosion is increasing significantly probably because the dense protective cover of annual plants decrease and shrubs' vegetation cover increases. At the same time, bare soil surface below the shrubs' foliage increases as well, while drystone terraces supporting soil material and runoff water collapse. When slope gradient is very steep (40%), soil sediment losses remain at the same high levels after cultivation abandonment because slope gradient is the main factor controlling soil erosion, although soil and vegetation properties are changing.

Analytical methods for tracing pharmaceutical residues in water and wastewater

Abstract: The focus of environmental analysis and determination of chemicals in the environment has recently been extended from the more classical pollutants to new contaminant categories including pharmaceuticals This is attributed mainly to the development of new analytical techniques including liquid chromatography with tandem mass spectrometry (LC-MS 2 ) and gas chromatography with mass spectrometry (GC-MS), which enable the determination of such compounds down to the ng/l level This article reviews the most recent developments and applications within water and wastewater environmental matrices

Multiple meanings and modes: on the many ways to be a generalist flower

Abstract: The concept of a generalist flower appears to mean different things to different people, depending upon their background and training We assess the different meanings of generalist flowers with respect to the ecological "set and setting" of pollination, and then we discuss notions of ecological, functional and phenotypic generalization These ideas are explored in more detail using examples from our own published and unpublished studies on the pollination ecology of Daucus carota, Hedera helix, and Chamerion angustifolium, and from the published work of other researchers Finally we relate these ideas and clarified definitions of "generalist" and "specialist" flowers to the pollination syndrome concept

Issues in computer supported inquiry learning in science

Abstract: Current views on science learning state that this should not involve learning just about the established results of science, including well-established theories such as Newtonian mechanics or the evolution of species as well as important empirical discoveries such as Young’s double slit experiment or the structure of DNA. Instead science learning should also focus on the processes and methods used by scientists to achieve such results. One obvious way to bring students into contact with the scientific way of working is to have them engage in the processes of scientific inquiry themselves, by offering them environments and tasks that allow them to carry out the processes of science: orientation, stating hypotheses, experimentation, creating models and theories, and evaluation (de Jong 2006a). Involving students in the processes of science brings them into the closest possible contact with the nature of scientific understanding, including its strengths, problems and limitations (Dunbar 1999). This is the main claim of inquiry learning: engaging learners in scientific processes helps them build a personal knowledge base that is scientific, in the sense that they can use this knowledge to predict and explain what they observe in the natural world. For about the last 20 years, computers have been used to create environments that engage learners in scientific inquiry activities. The virtue of the computer is that it allows the scaling down of inquiry tasks to a manageable size for learners who are inexperienced with inquiry processes. There are several ways in which computers can help create challenging and manageable environments for inquiry learning: • Replacing the natural world by a computer simulation can help make available on a wide scale the phenomena to be investigated. Moreover, the simulation may be simplified and/or emphasize certain aspects of the domain that can help learners observe critical features of the domain (van Joolingen & de Jong 1991a; de Jong & van Joolingen 1998; de Jong 2006a). • The computer can offer tools that support the inquiry processes, such as tools to analyse or visualize data, tools that help learners state hypotheses and tools that help learners manage the learning process (van Joolingen 1999; Linn et al. 2004a; Quintana et al. 2004; de Jong 2006b). • The computer can support collaboration between learners, allowing them to communicate, share data, results and ideas, and discuss consequences for the knowledge that is under construction (Okada & Simon 1997; van Joolingen et al. 2005). • Computer-based modeling tools allow learners to express their theories in models that can be simulated. In this way learners can use their theories operationally, confronting themselves with the consequences of their ideas (Hestenes 1987; Schecker 1993; Jackson et al. 1996; Fretz et al. 2002; Zhang et al. 2002; Schwarz & White 2005).

Geomorphosite assessment and management in protected areas of Greece Case study of the Lesvos island – coastal geomorphosites

Abstract: . This paper presents a methodology for assessment of geomorphosites located in protected areas. The methodological process involves definition of «geomorphological value» of all sites using six criteria: 1) «scientific» and «educational value»; 2) geodiversity, 3) «ecological» and «aesthetic value»; 4) «cultural value»; 5) potential threats and protection needs; and 6) potential for use. The assessment method was implemented in Greece on various geomorphosites at different scales: landscape scale (national parks and monuments) and landform scale (Lesvos Island Geopark). For this purpose, eight representative national parks and natural monuments were classified and assessed using the proposed methodology at a large scale. The same methodology was also used to evaluate 15 distinet geomorphosites found in the coastal zone of the Lesvos Petrified Forest Geopark. Here, geomorphosites of different sizes and categories were selected, classified and assessed. In order to protect the identified geomorphosites and ensure their proper management, the Natural History Museum of the Lesvos Petrified Forest, which is the management structure of the Lesvos Geopark, proposed the development of the Western Lesvos Marine Park. This park is to include the existing coastal visiting parks and a series of geomorphosites and marine fossil Sites.

3D Mesh Segmentation Methodologies for CAD applications

Abstract: D mesh segmentation is a fundamental process for Digital Shape Reconstruction in a variety of applications including Reverse Engineering, Medical Imaging, etc. It is used to provide a high level representation of the raw 3D data which is required for CAD, CAM and CAE. In this paper, we present an exhaustive overview of 3D mesh segmentation methodologies examining their suitability for CAD models. In particular, a classification of the various methods is given based on their corresponding underlying fundamental methodology concept as well as on the distinct criteria and features used in the segmentation process.

Integrating Web 2.0 in e-learning environments: a socio-technical approach

Abstract: The great diffusion of Web 2.0 is having a tremendous effect and change on the way people search, find, collaboratively develop and consume information and knowledge. Education and learning are not an exception of Web 2.0 trends, as the number of Web 2.0 empowered e-learning environments are booming. Although research in Web 2.0 applications in learning is rising, the studies tend to be very descriptive failing to identify and discuss the pedagogical theories and models that support and enhance the exploitation of Web 2.0 tools in (e)-learning environments. This paper aims to first discuss the use of Web 2.0 in (e)-learning and the new skills that they enable, and then, debate the pedagogical theories that support the exploitation of Web 2.0 for creating personalised and collaborative learning environments. To achieve that, a socio-technical approach is suggested.

Potential growth and biomass productivity of Miscanthus×giganteus as affected by plant density and N-fertilization in central Greece

Abstract: The potential growth and biomass productivity of Miscanthus×giganteus was investigated under constraint-free conditions during two years with appreciable different climatic conditions in central Greece, and under three different plant densities (0.66, 1, 2 pl m−2) and two different nitrogen dressings ( N 0 = 50 , N1=100 kg N ha−1). The field experimental design was a 3×2 factorial split plot in four blocks. Plant height, tiller number, leaf area index and dry weight per plant component were measured in subsequent harvests throughout the growing periods of 2001 and 2002. It was found that fertilisation within the studied rates did not affect growth and biomass productivity of the crop, and no interaction between fertilization and plant density was observed in any of the samplings. Contrary to fertilization, a significant effect of plant density was found, with the denser populated plants (10,000–20,000 pl ha−1) performing growth rates of 250–350 kg ha−1 d−1 for large parts of the growing period, reaching maximum dry biomass yields in excess of 38 t ha−1 in the more favorable year, 2002, and 28 t ha−1 in the warmer and drier year 2001. Such high yield potentials were explained by the particularly great assimilation rates of this crop that were also measured under light saturation and optimum temperature and water regimes. With such biomass yields (11.2–15.2 t ha−1 oil equivalent), obtainable particularly under modest fertilisation needs, Miscanthus sinensis should be considered as a very promising crop for biomass production in Greece in the near future.

Effects of pulsed nutrient inputs on phytoplankton assemblage structure and blooms in an enclosed coastal area

Abstract: The response of phytoplankton assemblage structure to terrestrial nutrient inputs was examined for the Gulf of Kalloni in the Northern Aegean Sea, a productive semi-enclosed coastal marine ecosystem. The study was focused on a typical annual cycle, and emphasis was placed on the comparative analysis between blooms developing after significant nutrient inputs from the watershed, and naturally occurring blooms. Baseline information was collected on a monthly basis from a network of stations located in the oligotrophic open sea and the interior and more productive part of the embayment. Intensive sampling was also carried out along a gradient in the vicinity of a river which was the most important source of freshwater and nutrient input for the Gulf. Phytoplankton assemblage structure was analyzed from 188 samples using diversity indices (Shannon and Average Taxonomic Distinctness), multivariate plotting methods (NMDS), multivariate statistics (PERMANOVA), and canonical correspondence analysis (CCA). Three characteristic assemblages were recognized: (1) an autumn assemblage developed under nutrient depleted conditions, having low diversity due to the dominance of two small diatoms, (2) a winter bloom of the potentially toxic species Pseudo-nitzschia calliantha occurring immediately after a nutrient peak and characterized by very low diversity, and (3) a naturally occurring early summer bloom of centric diatoms with relatively high diversity. The results of the study support the view that moderate nutrient inputs may have a beneficial effect on the functioning of coastal ecosystems, stimulating the taxonomic diversity through the growth of different taxonomic groups and taxa. On the other hand, a sudden pulse of high nutrient concentrations may greatly affect the natural succession of organisms, have a negative effect on the diversity through the dominance of a single species, and can increase the possibility of a harmful algal bloom development.

Top-k Spatial Preference Queries

Abstract: A spatial preference query ranks objects based on the qualities of features in their spatial neighborhood. For example, consider a real estate agency office that holds a database with available flats for lease. A customer may want to rank the flats with respect to the appropriateness of their location, defined after aggregating the qualities of other features (e.g., restaurants, cafes, hospital, market, etc.) within a distance range from them. In this paper, we formally define spatial preference queries and propose appropriate indexing techniques and search algorithms for them. Our methods are experimentally evaluated for a wide range of problem settings.

Social and cultural capital in educational research: issues of operationalisation and measurement

Abstract: This article aims to contribute to the debate of how theoretical concepts can be operationalised when researching educational issues. Specifically, it examines the application of the concepts of social and cultural capital in empirical research seeking to provide explanations for educational processes relating to post‐secondary school choice making in contemporary Cyprus. The article argues that there are limitations in the various ways social and cultural capital are operationalised quantitatively in empirical research as often they do not capture adequately the full extent of the social dynamics that they draw attention to. Instead the use of qualitative methods where the researcher probes for details into the practices, habits, beliefs, and attitudes of individuals are seen as having powerful exploratory and explanatory potentials to address these limitations.

Patient Fall Detection using Support Vector Machines

Abstract: This paper presents a novel implementation of a patient fall detection system that may be used for patient activity recognition and emergency treatment. Sensors equipped with accelerometers are attached on the body of the patients and transmit patient movement data wirelessly to the monitoring unit. The methodology of support Vector Machines is used for precise classification of the acquired data and determination of a fall emergency event. Then a context-aware server transmits video from patient site properly coded according to both patient and network status. Evaluation results indicate the high accuracy of the classification method and the effectiveness of the proposed implementation.

Words versus character n-grams for anti-spam filtering

Abstract: The increasing number of unsolicited e-mail messages (spam) reveals the need for the development of reliable anti-spam filters. The vast majority of content-based techniques rely on word-based repr...

Placing late Neanderthals in a climatic context.

Abstract: Attempts to place Palaeolithic finds within a precise climatic framework are complicated by both uncertainty over the radiocarbon calibration beyond about 21,500 14C years bp and the absence of a master calendar chronology for climate events from reference archives such as Greenland ice cores or speleothems. Here we present an alternative approach, in which 14C dates of interest are mapped directly onto the palaeoclimate record of the Cariaco Basin by means of its 14C series, circumventing calendar age model and correlation uncertainties, and placing dated events in the millennial-scale climate context of the last glacial period. This is applied to different sets of dates from levels with Mousterian artefacts, presumably produced by late Neanderthals, from Gorham's Cave in Gibraltar: first, generally accepted estimates of about 32,000 14C years bp for the uppermost Mousterian levels; second, a possible extended Middle Palaeolithic occupation until about 28,000 14C years bp; and third, more contentious evidence for persistence until about 24,000 14C years bp. This study shows that the three sets translate to different scenarios on the role of climate in Neanderthal extinction. The first two correspond to intervals of general climatic instability between stadials and interstadials that characterized most of the Middle Pleniglacial and are not coeval with Heinrich Events. In contrast, if accepted, the youngest date indicates that late Neanderthals may have persisted up to the onset of a major environmental shift, which included an expansion in global ice volume and an increased latitudinal temperature gradient. More generally, our radiocarbon climatostratigraphic approach can be applied to any 'snapshot' date from discontinuous records in a variety of deposits and can become a powerful tool in evaluating the climatic signature of critical intervals in Late Pleistocene human evolution.

Detecting DNS amplification attacks

Abstract: DNS amplification attacks massively exploit open recursive DNS servers mainly for performing bandwidth consumption DDoS attacks. The amplification effect lies in the fact that DNS response messages may be substantially larger than DNS query messages. In this paper, we present and evaluate a novel and practical method that is able to distinguish between authentic and bogus DNS replies. The proposed scheme can effectively protect local DNS servers acting both proactively and reactively. Our analysis and the corresponding real-usage experimental results demonstrate that the proposed scheme offers a flexible, robust and effective solution.

Biodiversity and ecosystem functioning: reconciling the results of experimental and observational studies

Abstract: Biodiversity and ecosystem functioning research has been some of the most controversial of the last decade but rapid progress has been made by deriving hypotheses from the differing view points and challenging them with appropriate experimental and analytical tests (Loreau et al. 2001). Here we address some recent criticisms of the BIODEPTH project (Thompson et al. 2005) and show that: 1. While legume species play an important role in the BIODEPTH results, patterns are not generally consistent with the multispecies sampling effect for legumes proposed by Huston & McBride (2002) as suggested in Thompson et al. (2005). 2. The BIODEPTH results are also not consistent with transient biodiversity effects. Levels of species diversity were generally maintained over the 3 years of the project (i.e. little competitive exclusion) and diversity-productivity relationships in BIODEPTH generally strengthened during the experiments.

Region of Interest Coding Techniques for Medical Image Compression

Abstract: We have provided an overview of state-of-the-art ROI coding techniques applied to medical images. These techniques are classified according to the image type they apply to; thus the first class includes ROI coding schemes developed for two-dimensional (2-D) still medical images whereas the second class consists of ROI coding in the case of volumetric images. In the third class, a prototype ROI encoder for compression of angiogram video sequences is presented. ROI coding preserves image quality in diagnostically critical regions by performing advanced image compression, enabling better image examination and addressing issues regarding image handling and transmission in telemedicine systems. The mapping of the ROI from the spatial domain to the wavelet domain is dependent on the used wavelet filters and it is simplified for rectangular and circular regions. Therefore, ROI coding is considered quite important in distributed and networked electronic healthcare.

Detecting unauthorized and compromised nodes in mobile ad hoc networks

Abstract: Security of mobile ad hoc networks (MANET) has become a more sophisticated problem than security in other networks, due to the open nature and the lack of infrastructure of such networks. In this paper, the security challenges in intrusion detection and authentication are identified and the different types of attacks are discussed. We propose a two-phase detection procedure of nodes that are not authorized for specific services and nodes that have been compromised during their operation in MANET. The detection framework is enabled with the main operations of ad hoc networking, which are found at the link and network layers. The proposed framework is based on zero knowledge techniques, which are presented through proofs.