Conference Papers / Δημοσιεύσεις σε Συνέδρια

5G wireless is the next step in the evolution of mobile communications with the aim being to provide connectivity for any kind of device and any kind of application. Wireless Body Area Networks (WBANs) constitute just one component of connected healthcare utilising small intelligent physiological sensors either on or implanted in the human body. This contribution examines the 5G technologies that will make a significant contribution to providing secure healthcare-orientated WBANs with improved energy efficiency, interference mitigation and wireless power transfer capability.

Cancer is one of the leading fatal diseases in the western world and many approaches have been proposed for both its treatment and prevention. Several of these approaches are dealing with the use of chemicals or with the use of signaling molecules that interfere with critical pathways in cancer progression. Yet, there is still a lot to be learned for the biology and mechanisms of oncogenesis, tumor progression, and tumor biology in general. What that has been neglected throughout the years is the understanding of biological systems from the physical perspective and the understanding of their mechanisms from the physical point of view. Since living systems could be considered as physical systems, there exists the possibility of examining biological phenomena under this perspective. In the present work we use computational and physical approaches to study and model the tolerance limits and mechanics of cell membranes. Our scope is to gain a better understanding of these phenomena and potentially use them for therapeutic purposes, since we are referring to tumor cells.

This paper provides an overview of the construction of a conceptual framework regarding ICT-Assistive Technology (ICT-AT) competence development, designed to gain awareness of the elements involved and to facilitate the understanding and exchange among stakeholders of the ENTELIS (European Network for Technology Enhanced Learning in an Inclusive Society) project. The framework was designed based on the basic principles of Activity Theory, which however have been adapted and adjusted to the project's objectives. Hence, it includes a map of actors and other parameters functioning in a person surrounding 'ecosystem', and it allows us to understand and map roles, expectations, barriers, as well as to devise solutions to tackle digital divide. Taking as a starting and central point the person and his/her wish to self-determination and fulfilment (quality of life) and the related needs, it provides a map of how the various concepts and variables interact within the theoretical and methodological perspective of the collection, description and assessment of experiences in ICT-AT education and competences development of persons with disabilities (PwD) of all ages. The conceptual framework represents two interacting learning activity systems: (a) the internal system of the end-user, which includes the end-user and his/her needs, the setting where learning takes place and the other actors involved, and (b) the external system, which embraces the internal system but also wider issues of policy and practice and experiences and 'actors' that contribute to the development and use of ICT and ICT-AT skills in all areas of life. The elements of these systems and their interaction provide the basis for analysing experiences and advancing knowledge relevant for bridging the digital divide.

Genetic programming has rarely been applied to manufacturing optimisation problems. In this report we investigate the potential use of genetic programming for the solution of the one-machine total tardiness problem. Combinations of dispatching rules are employed as an indirect way of representing permutations within a modified genetic programming framework. Hybridisation of genetic programming with local search techniques is also introduced, in an attempt to improve the quality of solutions. All the algorithms are tested on a large number of benchmark problems with different levels of tardiness and tightness of due dates.

Consider a network vulnerable to viral infection, where the security software can guarantee safety only to a limited part of it. We model this practical network scenario as a non-cooperative multi-player game on a graph, with two kinds of players, a set of attackers and a protector player, representing the viruses and the system security software, respectively. We are interested in the associated Nash equilibria, where no network entity can unilaterally improve its local objective. We obtain the following results: For certain families of graphs, mixed Nash equilibria can be computed in polynomially time. These families include, among others, regular graphs, graphs with perfect matchings and trees. The corresponding price of anarchy for any mixed Nash equilibria of the game is upper and lower bounded by a linear function of the number of vertices of the graph. (We define the price of anarchy to reflect the utility of the protector). Finally, we introduce a generalised version of the game. We show that the existence problem of pure Nash equilibria here is NP-complete.

Consider an information network with threats called attackers; each attacker uses a probability distribution to choose a node of the network to damage. Opponent to the attackers is a protector entity called defender; the defender scans and cleans from attacks some part of the network (in particular, a link), which it chooses independently using its own probability distribution. Each attacker wishes to maximize the probability of escaping its cleaning by the defender; towards a conflicting objective, the defender aims at maximizing the expected number of attackers it catches. We model this network security scenario as a non-cooperative strategic game on graphs. We are interested in its associated Nash equilibria, where no network entity can unilaterally increase its local objective. We obtain the following results: • We obtain an algebraic characterization of (mixed) Nash equilibria. • No (non-trivial) instance of the graph-theoretic game has a pure Nash equilibrium. This is an immediate consequence of some covering properties we prove for the supports of the players in all (mixed) Nash equilibria. • We coin a natural subclass of mixed Nash equilibria, which we call Matching Nash equilibria, for this graph-theoretic game. Matching Nash equilibria are defined by enriching the necessary covering properties we proved with some additional conditions involving other structural parameters of graphs, such as Independent Sets. - We derive a characterization of graphs admitting Matching Nash equilibria. All such graphs have an Expanding Independent Set. The characterization enables a non-deterministic, polynomial time algorithm to compute a Matching Nash equilibrium for any such graph. - Bipartite graphs are shown to satisfy the characterization. So, using a polynomial time algorithm to compute a Maximum Matching for a bipartite graph, we obtain, as our main result, a deterministic, polynomial time algorithm to compute a Matching Nash equilibrium for any instance of the game with a bipartite graph.

We present a new model for the infrared emission of the high redshift hyperluminous infrared galaxy IRAS F10214+4724 which takes into account recent photometric data from Spitzer and Herschel that sample the peak of its spectral energy distribution. We first demonstrate that the combination of the AGN tapered disc and starburst models of Efstathiou and coworkers, while able to give an excellent fit to the average spectrum of type 2 AGN measured by Spitzer, fails to match the spectral energy distribution of IRAS F10214+4724. This is mainly due to the fact that the ν S ν distribution of the galaxy falls very steeply with increasing frequency (a characteristic of heavy absorption by dust) but shows a silicate feature in emission. We propose a model that assumes two components of emission: clouds that are associated with the narrow-line region and a highly obscured starburst. The emission from the clouds must suffer significantly stronger gravitational lensing compared to the emission from the torus to explain the observed spectral energy distribution.

Two fire growth models for enclosures have been developed using a stochastic and a probabilistic approach. The first is based on probability tree analysis, while the second one is a typical Markov approach to the problem. A state transition model was built in order to provide the appropriate transition probabilities needed by the two models and a deterministic mainframe was used in order to close the set of equations in the probabilistic model. New criteria for the definition of the mean time spent in each of the fire stages are proposed and finally results from both approaches are compared to each other and with previous analysis. Results from a nationwide survey are used to furnish the models. The study concentrates on the development of a new risk assessment framework for use by the Cypriot manufacturing industry and it is funded by the Cyprus Research Promotion Foundation. An infamous catastrophe in the Cypriot manufacturing industry is used to illustrate the examples.

Network Flying Platforms (NFPs) such as unmanned aerial vehicles, unmanned balloons or drones flying at low/medium/high altitude can be employed to enhance network coverage and capacity by deploying a swarm of flying platforms that implement novel radio resource management techniques. In this paper, we propose a novel layered architecture where NFPs, of various types and flying at low/medium/high layers in a swarm of flying platforms, are considered as an integrated part of the future cellular networks to inject additional capacity and expand the coverage for exceptional scenarios (sports events, concerts, etc.) and hard-to-reach areas (rural or sparsely populated areas). Successful roll-out of the proposed architecture depends on several factors including, but are not limited to: network optimisation for NFP placement and association, safety operations of NFP for network/equipment security, and reliability for NFP transport and control/signaling mechanisms. In this work, we formulate the optimum placement of NFP at a Lower Layer (LL) by exploiting the airborne Self-organising Network (SON) features. Our initial simulations show the NFP-LL can serve more User Equipment (UE)s using this placement technique.

There exists a huge variety in the occurrence and characteristics of major incidents. Incident management stakeholders and in particular emergency health service providers have to deal with two basic challenges: The disproportion between the needs and the available human/material resources in the response capacity and the inherent time constraints of an emergency. These critical factors play a seminal role in the decision-making process during a crisis event, which affects all levels of command & control (strategic, operational, and tactical). The drawback with current health emergency management systems lies with the command & control operations that should coordinate the actions of the separate services and turn them into an effective, multi-faceted crisis response mechanism. IMPRESS improves the efficiency of decision making in emergency health operations, which has a direct impact on the quality of services provided to citizens. Furthermore it provides a consolidated concept of operations, to effectively manage medical resources, prepare and coordinate response activities, supported by a Decision Support System, using data from multiple heterogeneous sources. The proposed solution facilitates communication between Health Services (and Emergency Responders) at all levels of response and the crisis cycle with the necessary health care systems support, supervision and management of participating organizations. It will assist health services in becoming more proactive, better prepared and interoperable with other emergency response organizations.

Central to smart home security is the need for adequate surrounding awareness. Security systems have been designed for remote exploration and control, however, these still lack the simplicity needed by elderly and disabled. The majority of elderly people find the control of such systems laborious. This highlights the need for usable designs that take into consideration the cognitive limitations of this category of people. This paper contributes towards this problem through the introduction of a novel vehicular Remote Exploration Surveillance Robot (RESBot), capable of monitoring in real time the environment in response to events. The interaction with the system is achieved through natural language commands and hence, provides improved usability over traditional approaches. Results from the experimental usability evaluation of the RESBot system revealed considerable improvement over conventional home security systems.

In order to support schools to assess their performance in supporting children with disabilities in their ICT and ICT-AT needs, a self-assessment framework was developed by a task force of partners and associate partners of the ENTELIS project. The self-assessment tool aims to help educational establishments that welcome learners with disabilities to assess their current outcomes and to plan improvements in supporting these students in increasing digital literacy and developing digital skills. This includes the use of mainstream Information and Communication Technology (ICT) and specially designed digital Assistive Technologies (ICT-AT). This can only successfully happen if schools fully embrace an inclusive approach to education. In this paper the authors describe the development of the framework and the further steps for its use.

Magnetic Resonance (MRI), Computed Tomography (CT) and Ultrasound (US) are three of the most commonly used clinical imaging modalities. The aim of this study was to establish a Quality Assurance program for MRI, CT and US scanners. A well-designed quality assurance program is of utmost importance in the clinical setting, because it indicates whether diagnostic imaging modalities meet the minimum criteria of acceptable performance and because it helps determine those scanner parameters that need adjustment in order to ensure optimum performance. Quality assurance programs that rely on manual data collection and analysis are tedious and time consuming and are often abandoned due to the significant workload required for their implementation. In this paper we describe an integrated software system for automating the process of data collection and management in Quality Assurance for diagnostic radiological imaging. The developed system is comprised of two main units: The Image Processing Unit (IPU) and the Data Management Unit (DMU). The IPU is used for analysing images from different diagnostic modalities in order to extract measurements. The IPU is dynamically linked to the DMU so that measurements are transferred directly to the DMU. This process allows the generation of quality assurance reports for all such modalities.

Rheumatoid arthritis is a chronic inflammatory disorder whose origin of defect has been the subject of extensive research during the past few decades. While a number of immune and non-immune cell types participate in the development of chronic destructive inflammation in the arthritic joint, synovial fibroblasts have emerged as key effector cells capable of modulating both joint destruction and propagation of inflammation. Ample evidence of aberrant changes in the morphology and biochemical behaviour of rheumatoid arthritis synovial fibroblasts have established the tissue evading and "transformed" character of this cell type. We have recently demonstrated that actin cytoskeletal rearrangements determine the pathogenic activation of synovial fibroblasts in modelled TNF-mediated arthritis, a finding correlating with similar gene expression changes which we observed in human rheumatoid arthritis synovial fibroblasts. Here, we show that pharmacological inhibition of actin cytoskeleton dynamics alters potential pathogenic properties of the arthritogenic synovial fibroblast, such as proliferation, migration and resistance to apoptosis, indicating novel opportunities for therapeutic intervention in arthritis. Recent advances in this field of research are reviewed and discussed.

Information hovering is relevant in vehicular ad hoc networks in cases where critical information needs to be made available to all vehicles in a bounded geographical area, called the hovering area, for a specific amount of time. In cases of low traffic density within the hovering area, a number of vehicles may not receive the critical information due to partitioning of the vehicular network. In previous work we proposed an information hovering scheme which increases the achieved reachability, by employing probabilistic flooding outside the hovering area. Informed vehicles outside the hovering area offer alternative paths towards the uninformed vehicles thus increasing reachability. In this work we investigate the robustness of the proposed protocol with respect to changing hovering area, transmission range of the vehicles and the message loss probability. We verify that the protocol continues to work effectively in all scenarios outperforming other approaches which have been proposed in literature. In addition, we investigate enhancements to the proposed protocol which ensure improved performance in cases of high traffic density within the hovering area. We apply probabilistic flooding within the hovering area and we observe that retransmission probabilities less than one suffice to lead to high reachability values.

The research discussed here comes from an ongoing multifaceted two-year program designed to explore the potential of tablet technologies for enhancing mathematics teaching and learning at the primary school level. The program is taking place within a public primary school in Cyprus, and aims at the effective integration of tablet technologies within the mathematics school curriculum. It has adopted a systemic approach to the introduction of mobile devices in the school setting that focuses on the broad preparation and on-going engagement of all key stakeholders involved in the educational process. In the article, we report on the main experiences gained from the first year of the program. We describe the content and structure of the program, and discuss its impact on teachers' knowledge, skills, and confidence in incorporating tablet technologies within the mathematics curriculum.

A number of probabilistic flooding schemes have been recently considered in VANETs to address problems of information dissemination in safety applications. The design approach has so far been simulative, a method which does not guarantee that the derived protocols will work when the simulation settings are violated in practice. In this paper, motivated by the need to design information dissemination protocols with verifiable properties prior to implementation, we employ mathematical models of single and multiple lane roads to investigate probabilistic flooding in VANETs using mathematical analysis. We demonstrate that the system can be described by linear difference equations the solutions of which yield the probability of all vehicles receiving the critical message as a function of the rebroadcast probability, the number of neighbors of each vehicle and the number of vehicles. We utilize the obtained solutions to derive the desired rebroadcast probabilities as a function of the transmission range, the vehicle density and the dissemination distance. The obtained results are in line with results obtained using extensive simulations and can be used as a baseline to develop information dissemination protocols with verifiable properties.

Following research attention to children's use and understanding of causation, in this paper we contend that young children as early as kindergarten are able to engage in an effort to develop understanding about the causal mechanism underlying or explaining physical and mathematical phenomena. We draw on a two examples from early childhood education settings to suggest that children are able to use (novice) abilities of mechanistic reasoning both in early science and mathematics education. We discuss implications for the role of the teacher and activity design.

The worldwide declining numbers of students enrolled in educational degrees related to engineering disciplines led to the gradual decrease of qualified engineers who are necessary for the implementation of fundamental societal functions. It is therefore imperative that the number of students studying engineering must increase. This paper discusses good practices employed by academic institutions in order to increase the attractiveness of their engineering studies. The discussion is based on the results of a pan-European survey conducted in the context of the Academic Network of European and Global Engineering Education (EUGENE).

Several studies have focused on the different types of laboratories arising with the evolution of technology and their influence within all educational levels concerning Science, Technology, Engineering and Mathematics (STEM) Education. Augmented Reality (AR) is receiving increased attention and interest in recent years, within not only the commercial and the entertainment sectors, but also the educational field. In this paper, some current trends are identified after a brief overview of the state-of-the-art concerning Laboratory-based education. Moreover, challenges are discussed and potential future areas of research are identified. Finally, an outline of a methodology is suggested aiming to identify how the use of different types of labs may affect students' enrollment in STEM-related studies.