Effects of Anthropogenic Influences on the Trophic State,Land Uses and Aquatic Vegetation in a Shallow Mediterranean Lake: Implications for Restoration

Lake Pamvotis, NW Greece is a shallow Mediterranean eutrophic lake that has changed drastically over the past 50 years. Strong effects, resulted mainly from anthropogenic causes, in the hydrological regime are shown for this area using long term hydrological data and a GIS system for extracting land cover/use changes. A set of aerial imagery acquired in 1945 through 2002 were used to monitor and assess the spatial and temporal changes in land cover/use, focused mainly on the lake’s surface area and its surrounding ecosystem (Natura 2000 area). The significance of the changes in land cover/use distribution within Pamvotis wetland is further discussed depicting the role of the anthropogenic influence on the fragile ecosystem that resulted in the shrinkage of lake’s habitats extent. The purpose of this analysis was to examine the long-term changes on macrophyte community composition, species occurrence and relative abundance with water quality and water level changes over the past century, using historical data, aerial photos and GIS techniques. The results showed that for the last 25 years annual water level fluctuation ranged from 70 to 159 cm. Water level starts decreasing in mid June and increasing again gradually from November until March–April. Intra annual water level fluctuation seems to be affected by land use for agricultural purpose through intensive irrigation and the summer drought as well. A dramatic decline of the submerged vegetation is apparent mainly attributed to anthropogenic pressures. Regarding the land cover/use changes, the most notable and significant alterations are concerning the urban development around the lake, the disappearance of wet meadows and the extension of reed beds. Finally it seems that water budget data as well as the response of the key eutrophication parameters are affected from both hydrological alterations and point/non-point pollution sources.     

Networked learning with user-enriched educational material

The scope and the philosophy of the use of New Technologies in education have still to be defined and important pedagogical issues arise. Based on experience of secondary technical vocational education, a general schema for Network-Based Learning with strong learner participation is proposed. The main concept of this approach is that learner participation in the learning process can produce or at least motivate the production of learning material. A pilot implementation of such an activity produced quite interesting results and indicated that the content of the learning material can be enriched by material produced by the trainees themselves.     

Environmental Monitoring of Spatio-temporal Changes Using Remote Sensing and GIS in a Mediterranean Wetland of Northern Greece

Loss and degradation of terrestrial and aquatic habitats and degraded water quality are major environmental concerns worldwide. Especially wetlands are sensitive ecosystems that are subject to stress from human activities. Remote sensing techniques have been primarily used to generate information on land cover/use changes. Geographical Information Systems (GIS) and remote sensing can be used to provide a rapid or a large-scale understanding of lake change and in developing lake management strategies. The principal objectives of this study are to monitor and assess the spatial and temporal changes in land cover/use by using GIS, and to determine the main environmental factors affecting these changes. This paper presents a case study for the application of integrated remote sensing and GIS data for the classification and monitoring of the spatial and temporal changes in land use types. The study was conducted in a small natural wetland of Lake Cheimaditida, located in the East Mediterranean region of Northern Greece. Data analysis was conducted using GIS software. During the past several decades Lake Cheimaditida wetland has been influenced by many anthropogenic activities. The variables chosen for the assessment included condition of wetland and lake areas, present extent of wetlands relative to historic area, cover of natural habitat, wetland disturbances, etc. These variables address catchments properties that are important for maintaining and improving wetland habitats and water quality and assessment of trends useful for environmental monitoring. Land cover/land use patterns were assessed and compared using aerial photographs taken in 1945, 1969, 1982, and 1996. Over this period, reed beds enormously increased by 1,655.19%, while open-water areas and peat lands decreased by 74.05 and 99.5%, respectively. The significance of the changes in land cover distribution within the Lake Cheimaditida wetland are discussed in relation to the historical pattern of reed beds colonization, the importance of Phragmites australis in the process and the implications for strategic management of freshwater wetland resources.     

Web-based teaching in software engineering

The introduction of the new technologies of computer networks and hypermedia systems in education seems promising. However, only through experimentation can the effectiveness of these technologies be demonstrated. This was the main objective of the EONT project, in the process of which the National Technical University of Athens adapted an introductory course in Software Engineering to a novel enriched instructional delivery mode. The existing course material was supplemented by Web-based courseware, integrated into a Web-based novel networked learning environment. In this article we report on the results of our research and development, concerning this particular course, and discuss the results that were obtained from our evaluation study.     

Assessment of the distribution of aerosols in the area of Athens with the use of Landsat Thematic Mapper data

Landsat high resolution images, at the spectral interval 0.45-0.52 mu m, are used in an effort to qualitatively assess distribution of aerosols in the greater Athens area. It is found that the spatial distribution of aerosols in Athens can be described by calculating the differences in optical density between two images, the one referring a pollution-free day and the second reflecting a day with an atmospheric pollution episode. Results are supported by a positive correlation between the differences in optical densities for the 'polluted' and 'pollution free' images, and the measured levels of sulphur dioxide and smoke in various city areas. Finally according to the above methodology, aerosols exhibit their highest concentration mostly in the industrialized region of Athens, to the west of the city's centre, as well as in a limited area in the centre of Athens.     

The spectrum of adult adenovirus pneumonia

Adenovirus pneumonia is endemic among infants and children. We report an adult case of adenovirus pneumonia causing respiratory failure and infection in the patient's spouse. The case in the spouse presented as an exacerbation of COPD.     

CRITON: A Hypermedia Design Tool

The WWW has turned into a development and run-time environment for large-scale and complex applications. Such sophisticated applications are being deployed in increasing numbers without having been developed according to appropriate methodologies, tools and quality standards. The reason is not only that the hypermedia industry resists to utilize formal methods, but also that these methods and corresponding tools are very few and of dubious standards. The consequence is that the hypermedia applications being developed are of poor functionality and lack qualities such as modifiability, usability and maintainability. Especially the design phase is one of the phases that lack sufficient support from methods and CASE tools. This paper presents CRITON, a cross platform tool, built to support a hypermedia design method within an integrated environment. CRITON manages all three aspects of hypermedia design: conceptual design, navigational design and graphical user interface design, utilizing well-established theories and practices from software as well as hypermedia engineering. It employs these designs to generate a preliminary, exemplary form of the hypermedia application for the purpose of assessing the designs before the implementation phase.     

Dimming/brightening in Athens: Trends in Sunshine Duration, Cloud Cover and Reference Evapotranspiration

Evidence of global dimming/brightening is mainly based upon few measurements of solar radiation. A need for more research supported and extended with the use of other climatic variables, such as sunshine duration, recorded for a longer time period and successfully used as a proxy for solar radiation over the past 80 years, has already been urged. Thus, in this study, residual sunshine duration series computed after removal of the cloudiness-related variability, from daily sunshine duration and cloudiness data measured at the National Observatory of Athens are used for highlighting global dimming or brightening periods in Athens, during the period 1951–2001. Furthermore, the consistency of trends in radiation records and their implications for the hydrological cycle and especially the trends in reference evapotranspiration are examined, during the period 1951–2001. The analysis focuses on the seasonal decadal variations, determines and explains the causes of the seasonal trends from the inter-annual and decadal variability of the sunshine duration during the last half past century, with a special emphasis in detecting possible sub-periods in Athens. The signs of trends in the modeled annual and seasonal reference evapotranspiration are estimated, according to the indicated global dimming/brightening periods.     

Modeling learning technology systems as business systems

The design of Learning Technology Systems, and the Software Systems that support them, is largely conducted on an intuitive, ad hoc basis, thus resulting in inefficient systems that defectively support the learning process. There is now justifiable, increasing effort in formalizing the engineering of Learning Technology Systems in order to achieve better learning effectiveness as well as development efficiency. This paper presents such an approach for designing Learning Technology Systems and their most popular specialization, the Web-based Learning Systems, by modeling them as business systems, using business-modeling methods. The aim is to provide an in-depth analysis and comprehension of the Learning Technology Systems and Web-based Learning Systems domain, that can be used for improving the systems themselves, as well as for building the supporting software systems. Our work is based upon the Learning Technology Systems Architecture standard of IEEE LTSC, on the empirical results of designing Web-based Learning Systems for university courses and on the practices of the Rational Unified Process and the Unified Modeling Language.