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AbstractAim of the study: Brainstem Auditory Evoked Responses (BAERS) and Vestibular Evoked Myogenic Potentials (VEMPS) are used for studying auditory and vestibular function, respectively. We have initiated a study of Multiple Sclerosis Patients, in order to investigate the diagnostic value of both recordings and in particular of the second VEMP wave n34-p44. We also comment on the hypothesis that the n34 and p44 VEMP components are of cochlear origin. Materials and Methods: We have studied 31 MS patients with auditory and /or vestibular symptoms. 9 patients presented with unilateral deafness (group 1), 8 with bilateral tinnitus (group 2) and 14 with vertigo (group 3). VEMPS and BAERS have been recorded and assessed. We also investigate 30 healthy volunteers recording VEMP to determine normal individual limits. Results: In Group 1, the second wave n34p44 gave as one abnormal case, out of total 9 cases, that at the same time is characterized as normal by the first VEMP wave p12n23. In Group 3, the second wave n34p44 give also information for one abnormal case, out of total 14 cases, that at the same time is characterized as normal by the first VEMP wave p12n23. Thus the second wave provides added non trivial diagnostic value. In group 1, VEMPS results regarding the fist wave p13n23 were normal. At the same time the n34-p44 was present in the unaffected ear only. Conclusively, n34p44 was absent in 7 patients, although the vestibular VEMPS component p13n23 was normal. In group 2, BAERS and all but one p13n23 were normal, yet n34p44 was bilaterally absent in 3 patients. In group 3, all but one BAERS were normal, while p13n23 wave was bilaterally absent in 6 patients and prolonged in 8 patients .The n34p44 complex was bilaterally absent in 3 patients. We found no association (“correlation”) between patients with abnormal VEMPS and patients with abnormal BAEPS in our study. We also found that the unilateral presentation of n34p44 wave in group 1 was related with abnormal BAERS in the affected ear. Conclusion: The second wave n34p44 provides added non trivial diagnostic value. It adds to the set of abnormal cases a clear (meaning cases otherwise normal for p13n23 wave) 11% in group1 and a 7% in group3. Another important result of our study (coming from group1) is the following. n34p44 wave is not present in all normal subjects; whenever it exists it is bilateral. In our patients its unilateral presentation was related with abnormal BAERS in the affected ear. This supports the hypothesis that n34p44 are of cochlear origin. Statistical methodsThe intraclass correlation coefficients of type C following a two way random model for measuring reliability was calculated. Side differences for all the factors were compared with the Wilcoxon signed ranks test since most of variables are not normally distributed. Differences for all the factors between our four groups were compared with nonparametric tests for two independent samples. We calculated group differences using the Wilcoxon rank two-sample test and the Mann-Whitney U test. Further we checked for possible associations between the various abnormalities performing a correspondence analysis. We did not choose a chi-squared test since entries in our crosstabulation table include counts smaller than 5. In all cases a significant difference indicates P<0.05. Novelty – Impact Στην εργασία αυτή διαπιστώνουμε για πρώτη φορά μέσω της στατιστικής επεξεργασίας ότι το δεύτερο μέρος της μετρούμενης κυματομορφής VEMP έχει σημαντική διαγνωστική αξία. Το εύρημα αυτό είναι κεφαλαιώδδους σημασίας για την χρησιμότητα των VEMPS ως μέθοδος διάγνωσης. Το δεύτερο μέρος της κυματομορφής μέχρι τώρα δεν είχε μελετηθεί διεξοδικά και δεν χρησιμοποιούνταν για διάγνωση. 11. Ferekidou E, Eleftheriadou A, Zarikas V, Kandiloros D, Yiotakis I, Ferekidis E, Korres S. “Acoustic Stapedial Reflex in normal adults: biological behaviour and determination of threshold levels by detecting the Admittance (Y) and his components Susceptance (B) and Conductance (G).” ORL, Journal Otorhinolaryngol Relat Spec. 2008;70(3):176-84. Epub 2008 Apr 8. AbstractObjective The aim of this study was to record the acoustic reflex threshold for the Admittance (Y), Susceptance (B) and Conductance (G) in a large sample of healthy subjects and to establish normative data. Study design Acoustic reflex threshold was determined in 100 healthy persons, divided in 5 age-related groups (20-29, 30-39, 40-49, 50-59 and 60-69) numbering 20 persons each. Detection was performed for (Y) and its components, (B) and (G) at 226, 678 and 1000 Hz probe tones, using reflex activator signals 500, 1000, 2000 and 4000 Hz. Results. Statistically significant difference was revealed between separate measurements. The lowest threshold level was recorded for Y at 226 Hz using stimulus 1000 Hz. Subjects belonging to different age groups had different reflex thresholds. Conclusion: Inclusion of measurements for B and G in acoustic reflex detection offer more detailed information about the middle ear status compared with Y alone, and appears to be sensitive in detecting subtle diseases. Novelty – Impact Στην εργασία αυτή μελετούμε για πρώτη φορά τις μεταβολές των acoustic thresholds για όλους του συνδυασμούς των συνιστωσών Y, B, G και για τρεις διαφορετικές συχνότητες probe tone και τέσσερεις διαφορετικές συχνότητες stimuli. H σημασία της μελέτης είναι μεγάλη διότι σε αρκετές περιπτώσεις ασθενών δεν καταγράφονται μετρήσεις για tone 226 Hz που χρησιμοποιείται ευρέως και έχει μελετηθεί.
«Thermodynamic description of the dynamic evolution of a stock market index» "European Journal of Economics, Finance and Administrative Sciences" Issue 16 (2009), ISSN 1450-2887 Abstract: In this paper we present a phenomenological analysis for the time evolution of a Stock Index. We introduce a model that represents a new methodology for the description of the up and down trends of a stock index and we present an example referring to the Athens Stock Index (ASI). The day-by-day closing prizes of the ASI exhibit exponential laws. This behavior supports an alternative formalism based on the thermodynamic concepts of Physics in order to study the macroscopic properties of stock markets. Hence, we introduce Newton’s law of cooling as a pattern for up and down trends of the ASI. The results encourage us to construct a more complete thermodynamic model in order to understand the time evolution and the behavior of the ASI. Novelty – Impact Στην εργασία αυτή μελετούμε για πρώτη φορά τις μεταβολές ενός χρηματιστηριακού δείκτη βασισμένοι σε ένα μαθηματικό μοντέλο που προσεγγίζει με θερμοδυναμικό τρόπο τα εισοδήμα που ανταλλάσονται στις συναλλαγές. Ο ανάλογος της θερμοδυναμικής νόμος ψύξης και θέρμανσης βρίσκει εφαρμογή στη άνοδο ή στην κάθοδο ενός δείκτη.
“Oligomenorrhea in adolescents with Type 1 Diabetes Mellitus: relationship with the glycaemic control” European Journal of Obstetrics & Gynecology and Reproductive Biology 153 (2010) 62–66 Abstract: Objective: To investigate oligomenorrhea in adolescents with type 1 diabetes and the possible relation with the glycaemic control. Study Design: The study group consisted of 81 female adolescents with type 1 diabetes with a mean age of 15.0 years (range 12-18) and the control group of 205 healthy adolescents with a mean age of 15.5 years (range 12-18). Data on menstruation were collected by two parallel self-administered questionnaires. Oligomenorrhea was defined as having menstrual cycle length longer than 36 days during the last year. The metabolic control of diabetes was evaluated by calculating the mean value of HbA1c during the last year. Results: Age at menarche was greater for adolescents with type 1 diabetes (11.7 ± 1.2 vs. 12.2 ± 1.4, p-value<0.000) compared to healthy age-matched controls. Logistic regression analysis with oligomenorrhea as the dependent binary variable revealed an odds ratio equal to 7.8 (95% CI 3.411-17.853) for adolescents with type 1 diabetes (p-value<0.000). Finally, a second logistic regression analysis, concerning only patients of type 1 diabetes and for the same binary, estimated an odds ratio 4.8 (95 % CI 1.784-13.057, p-value<0.002) for HbA1c, and an odds ratio 5.3 (95 % CI 1.821-15.130, p-value<0.002) for the frequency of hypoglycaemia Conclusion: In adolescents with type 1 diabetes menarche occurs later while oligomenorrhea is more frequent. The relative risk for having oligomenorrhea is larger for increased values of HbA1c or for larger values of frequency of hypoglycaemia.
Στην εργασία αυτή έχω πραγματοποιήσει τον στατιστικό σχεδιασμό καθώς και την στατιστική ανάλυση των δεδομένων στηριζόμενος σε ένα στατιστικό μοντέλο για ομάδες υγειών και ασθενών και πραγματοποιώντας logistic (binary) regression analysis. Τέλος ανέπτυξα forward (likelihood ratio) επιλογή των covariates. 14. V. Zarikas, V. Gikas, C.P. Kitsos «Evaluation of the optimal design “cosinor model” for enhancing the potential of robotic theodolite kinematic observations» Measurement, Volume 43, Issue 10, December 2010, Pages 1416-1424 Abstract: The aim of the present work is to assess and to demonstrate the benefits of adopting optimal experimental design theory and techniques in order to enhance the potential of field data recorded using conventional geodetic instruments. More specifically, this research focuses on Robotic Total Stations (RTS) and in kinematic applications of geodetic positioning that exhibit a cyclic/periodic pattern of motion. The computational approach adopted follows from the principles of c- and D-optimal design criteria. Data processing involves computing the amplitude of motion in two ways; (a) using a sample of consecutively ordered data recordings and (b) using a sample respecting the optimal design criteria. Analysis, confirms the utility of the method resulting an improvement (i.e. a reduction) of the oscillation amplitude variance. This conclusion applies particularly at higher frequencies of oscillations (>1 Hz). This is important as at higher frequencies the performance of RTS deteriorates, and hence large variances occur Novelty – Impact Στην εργασία αυτή αναπτύσουμε μία optimal design μαθηματική τεχνική η οποία για ημιτονοειδούς τύπου μετρήσεις μας υποδεικνύει που πρέπει να πραγματοποιήσουμε τις μετρήσεις μας για ελαχιστοποίηση της διασποράς των δεδομένων. Τα αποτελέσματα της μαθηματικής ανάλυσης εφαρμόστηκαν σε δεδομένα από ένα συγκεκριμένο πείραμα με ρομποτικό θεοδόλιχο. Με αυτόν τον τρόπο δείχνουμε πόσο είναι το κέρδος μας χρησιμοποιώντας την προτεινόμενη optimal design μεδοδο.
Abstract There is a constant need for correct and meaningful statistical prediction. The General Linear Model (GLM) is a commonly used method to fit the data although most of the times the target is to construct a linear model in order to “predict” the value of the dependent variable; a goal for which GLM has not been designed for. The aim of the present study is to work on best model for a future observation, adopting the tolerance regions concept. A new method is explained and demonstrated, which is an alternative approach for choosing the optimal order of a response polynomial. The present study proposes a novel algorithm, which selects the best response polynomial, as far as prediction is concerned. The beta expected tolerance region is applied. The proposed computational approach has been applied for several data sets. This analysis, confirms the utility and the advantage of the method which provides non trivial results.
(εδώ τα ονόματα έχουν μπει αλφαβητικά κατόπιν συμφωνίας των συγγραφέων) Abstract A mechanism capable to provide a natural solution to two major cosmological problems, i.e. the cosmic acceleration and the coincidence problem, is proposed. A specific brane-bulk energy exchange mechanism produces a total dark pressure, arising when adding all normal to the brane negative pressures in the interior of galactic core black holes. This astrophysically produced negative dark pressure explains cosmic acceleration and why the dark energy today is of the same order to the matter density for a wide range of the involved parameters. An exciting result of the analysis is that the recent rise of the galactic core black hole mass density causes the recent passage from cosmic deceleration to acceleration. Finally, it is worth mentioning that this work corrects a wide spread fallacy among brane cosmologists, i.e. that escaping gravitons result to positive dark pressure.
Safety Science (impact factor: 1.36). 11/2013; 39. DOI:dx.doi.org/10.1016/j.ssci.2013.05.001, 2013 Abstract This work presents results from a statistical survey regarding accidents in elevators and escalators in Greece, based on data concerning accidents from the last 12 years. A main objective is to explore and uti-lize frequencies and ''correlations'' among the involved factors, in order to weight and evaluate crucial mistakes and misguided actions. Results will help preventing similar accidents for the technical staff and the users, as well as designing and teaching a new culture and attitude from the users' side. Various statistical inferences were derived related to regulations for the installation, service and operation of ele-vators. An important finding is that 65% of the reported accidents involve qualified servicing and instal-lation personnel or employees during their work, mainly associated with simultaneous violation of safety/health and internal electrical installations regulations. Other important outcomes concern associ-ations between number of victims and categories of building types or of severity of accidents as well as between severity of accidents and categories of type of violated regulations or of elevator type. Further-more, associations between severity of injury and categories of type of accident or of victims' age have been found. Proposals for the organization of the responsible authorities, data collection and prevention of similar serious accidents in the future are included.
Energy and Power Engineering 01/2013; 5(3):236-244. DOI:10.4236/epe.2013.53023., 2013 Abstract The present work proposes a methodological approach for modeling decisions regarding energy reduction in an elevator. This is achieved with the integration of existing as well as acquired knowledge, in a decision module implemented in the electronics of an elevator. So far, elevators do not exploit information regarding their recent usage. In the developed system decisions are driven based on information arising from monitoring the use of the elevator. Monitoring provides various records of usage which consequently are used to predict elevator’s future usage and to adapt accordingly its functioning. Till now, there are only elevators that encompass in their electronics algorithms with if then rules in order to control elevator’s functioning. However, these if then rules are based only on good practice knowledge of similar elevators installed in similar buildings. Even this knowledge which unavoidably is associated with uncertainty is not encoded in a mathematically consisted way in the algorithms. The design, the implementation and a first pilot evaluation study of an elevator’s intelligent decision module are presented. The study concludes that the presented application sufficiently reduces energy consumption through properly controlled functioning.
"On the Application of Cooperative Communications in Renewable Energy Sources for Maximizing the Reliability of Power Distribution Networks ", Journal of Green Engineering. 10/2013, 2013 Abstract In this paper, the efficiency of cooperative communications in power distri-bution networks is investigated, where a number of renewable energy sources (RESs) are deployed. Specifically, any medium voltage (MV) bus of the power distribution network is considered as a wireless relay node where the information gathered from each MV bus can be reliably transmitted to a con-trol station for further processing. Therefore, the power distribution network can be equivalently considered as a cooperative communication network. The average bit error rate of the proposed cooperative diversity network is studied and a closed-form lower bound is analytically derived. Numerical results cor-roborate the tightness of the proposed bound compared to the Monte Carlo simulations. The proposed wireless communication scheme enables the in-crease of the RES penetration level in distribution networks, improving so RES exploitation.
5-dimensional braneworld with gravitating Nambu-Goto matching conditions 12/2013; Source: arXiv (εδώ τα ονόματα έχουν μπει αλφαβητικά κατόπιν συμφωνίας των συγγραφέων) Abstract We continue the investigation of a recent proposal on alternative matching conditions for self-gravitating defects which generalize the standard matching conditions. The reasoning for this study is the need for consistency of the various codimension defects and the existence of a meaningful equation of motion at the probe limit, things that seem to lack from the standard approach. These matching conditions arise by varying the brane-bulk action with respect to the brane embedding fields (and not with respect to the bulk metric at the brane position) in a way that takes into account the gravitational back-reaction of the brane to the bulk. They always possess a Nambu-Goto probe limit and any codimension defect is seemingly consistent for any second order bulk gravity theory. Here, we consider in detail the case of a codimension-1 brane in five-dimensional Einstein gravity, derive the generic alternative junction conditions and find the Z_{2}-symmetric braneworld cosmology, as well as its bulk extension. Compared to the standard braneworld cosmology, the new one has an extra integration constant which accounts for the today matter and dark energy contents, therefore, there is more freedom for accommodating the observed cosmic features. One branch of the solution possesses the asymptotic linearized LFRW regime. We have constrained the parameters so that to have a recent passage from a long deceleration era to a small today acceleration epoch and we have computed the age of the universe, consistent with current data, and the time-varying dark energy equation of state. For a range of the parameters it is possible for the presented cosmology to provide a large acceleration in the high energy regime.
«Measurement and Analysis of Physicochemical Parameters Concerning Thermopylae Natural Hot Spring Waters» Journal of Applied Sciences 01/2014; 14(19):2331-2340. Abstract The present study describes a measuring station, implemented at the hot water source place, for collecting data of various physico-chemical factors. The integrated systems is able to continuously measure, process and transmit via a radio transmitter data regarding OPR, conductivity, water temperature and pH. An additional unit receives and stores data in convenient form for data analysis. The second part of the study presents a statistical study of the data with a time series analysis. The most important results are (1) Statistically significant correlations were found between the involved physico-chemical factors and (2) Data exhibit various periodicities.
Efficient electroweak baryogenesis by black holes DOI:arXiv:1406.6215 (εδώ τα ονόματα έχουν μπει αλφαβητικά κατόπιν συμφωνίας των συγγραφέων) Abstract ` A novel cosmological scenario, capable to generate the observed baryon number at the electroweak scale for very small CP violating angles, is presented. The proposed mechanism can be applied in conventional FRW cosmology, but becomes extremely efficient due to accretion in the context of early cosmic expansion with high energy modifications. Assuming that our universe is a Randall-Sundrum brane, baryon asymmetry can easily be produced by Hawking radiation of very small primordial black holes. The Hawking radiation reheats a spherical region around every black hole to a high temperature and the electroweak symmetry is restored there. A domain wall is formed separating the region with the symmetric vacuum from the asymmetric region where electroweak baryogenesis takes place. First order phase transition is not needed. The black holes's lifetime is prolonged due to accretion, resulting to strong efficiency of the baryon producing mechanism. The allowed by the mechanism black hole mass range includes masses that are energetically favoured to be produced from interactions around the higher dimensional Planck scale.
“Telemetry, analysis and wireless data communications for a measuring station” To appear in Advances in Electrical and Electronic Engineering 12/2014; Abstract “The present work describes the telemetric wireless communication system of a measuring station, implemented at the hot water source place. The telemetric unit of the measuring station collects continuously data of various physicochemical factors. The integrated systems is able to continuously measure, process and transmit via a radio transmitter data regarding radon, OPR, conductivity, water temperature and PH.An additional unit receives and stores data in convenient form for data analysis. The second part of the work presents a statistical study of the transmitted data based on a novel mathematical technique.” Β. ΔΗΜΟΣΙΕΥΣΕΙΣ ΣΕ ΔΙΕΘΝΗ ΕΠΙΣΤΗΜΟΝΙΚΑ ΣΥΝΕΔΡΙΑ ΜΕ ΠΕΡΙΟΔΙΚΟΤΗΤΑ ΚΑΙ ΜΕ ΠΛΗΡΗ ΚΡΙΣΗ (Fully Refereed International Conference with perioodicity) 1. Ian.Moss and Vasilios Zarikas "One loop corrected nucleation rates for the electroweak phase transition", preprint NCL95-TP5, Βρετανικό Συνέδριο Κοσμολογίας (Σεπτέμβριος 1995) στο DAMTP, Cambridge. (εδώ τα ονόματα έχουν μπει αλφαβητικά κατόπιν συμφωνίας των συγγραφέων) Abstract Bubble nucleation rates for the electroweak phase transition are calculated from the Higgs field effective action, up to first order in quantum corrections. A new parameterized form of the effective potential is presented and terms up to second order in derivatives are included in the effective action. These derivative terms enhance the nucleation rate, but they change the action by only a small amount as required by consistency, contrary to the previous estimations. Motivation. Η μελέτη της ηλεκτρασθένους μεταβολής φάσης απαιτεί την γνώση του finite temperature effective potential. Η εργασία αυτή υπολογίζει τις πρώτες κβαντικές διορθώσεις συμπεριλαμβάνοντας την συμβολή των κινητικών όρων της λαγκρατζιανής. Novelty-impact. Τα αποτελέσματα βρέθηκαν σύμφωνα με παρόμοια μελέτη από άλλη ερευνητική ομάδα, που διεξήχθη παράλληλα και δημοσιεύθηκε πρώτη. 2. Vasilios Zarikas, A. Paramythis, and C. Stephanidis ’’Decision-theoretic approaches to user interface adaptation: implications on Universal Access”. Proceedings of the “HCI International 2001, 9th International Conference on Human Computer Interaction, New Orleans, USA, 5-10 August”. Abstract This paper discusses the employment of decision-theoretic approaches in adaptive user interfaces, towards the goal of Universal Access. Specifically, the paper examines ways in which the requirements posed by Universal Access on human-computer interaction can be addressed through automatic user interface adaptation, using decision-theoretic frameworks. Furthermore, the paper discusses some of the implications of employing such adaptation frameworks in user interfaces intended for use by diverse user groups, in differing contexts of use. Motivation Η αρχή της παγκόσμιας πρόσβασης (Universal Access) είναι μία πολύ πρόσφατη αρχή, σύμφωνα με την οποία, το τμήμα του λογισμικού, που αφορά την επικοινωνία ανθρώπου-μηχανής, θα πρέπει να σχεδιάζεται και να αναπτύσσεται έτσι ώστε να μπορεί να προσαρμόζεται στις ξεχωριστές ιδιότητες/ανάγκες κάθε χρήστη και του περιβάλλοντός του. Οι διεπαφές αυτές είναι στο επίκεντρο της έρευνας και απαιτούν μαθηματικές τεχνικές τεχνητής νοημοσύνης για να υλοποιηθούν. Novelty – Impact Η εργασία αφού πρώτα κάνει ένα σύντομο review όλων των υλοποιημένων διεθνώς πληροφοριακών συστημάτων, που ενσωματώνουν μονάδες που χρησιμοποιούν την μαθηματική θεωρία απόφασης για διάφορες ενέργειες τους, προτείνει την χρήση συγκριμένων μαθηματικών εργαλείων για λήψη αποφάσεων και σε αυτοπροσαρμοζόμενες διεπαφές για πρώτη φορά. Η εργασία αυτή ουσιαστικά ανακοινώνει στο συνέδριο την χρήση decision engine στην κατασκευή του Nautilus Web browser (a follow-up to the AVANTI Web browser) ένα πρόγραμμα εγκεκριμένο και χρηματοδοτούμενο από το υπουργείο ανάπτυξης. 3. Vasilios Zarikas, G. Papatzanis, and C. Stephanidis “An architecture for a self-adapting information system for tourists”. Proceedings of the conference: “Human Computer Interaction with Mobile Devices, 10 Sept 2001, at IHM-HCI 2001, Lille, France”. Abstract The paper briefly describes the design of the architecture of the PALIO system (Personalised Access to Local Information and services for tOurists), focusing on the support for extensive adaptation. The framework provides a location-aware information system for tourists, capable of delivering fully adaptive information to a wide range of devices, including mobile ones. Its open and expandable architecture can integrate a variety of pre-existing or forthcoming services and retrieve information from a collection of different databases. It supports adaptability and dynamic adaptivity, according to user and context characteristics, both in the content and the presentation of information. Motivation Η δημοφιλής αρχή της παγκόσμιας πρόσβασης στην ανάπτυξη των διεπαφών, ουσιαστικά απαιτεί να είναι προσβάσιμη η πληροφορία από οποιονδήποτε χρήστη, με οποιαδήποτε συσκευή-πλατφόρμα και από οποιαδήποτε τοποθεσία. Novelty – Impact. Η εργασία αυτή παρουσιάζει, και περιγράφει συνοπτικά την αρχιτεκτονική ενός «έξυπνου» πληροφοριακού συστήματος για τουρίστες (PALIO project, χρηματοδοτούμενο από την Ε.Ε.), που σέβεται την αρχή της παγκόσμιας πρόσβασης και το οποίο αναπτύσει μία πλατφόρμα, ώστε να παραδίδεται προσαρμοζόμενη στον κάθε χρήστη πληροφορία, που να είναι η κατάλληλη με βάση τις προτιμήσεις του, την συσκευή που τυγχάνει να χρησιμοποιεί και τις ιδιότητες του χώρου, μέσα στον οποίο κινείται και αλληλεπιδρά με το σύστημα. Η προσαρμογή μάλιστα γίνεται αφενός στο περιεχόμενο της πληροφορίας, που θα παρουσιάζεται στον χρήστη και αφετέρου στον τρόπο παρουσίασης αυτής της πληροφορίας. Παρουσιάζονται επίσης και οι μονάδες που απαρτίζουν την συνολική αρχιτεκτονική. Μία από αυτές τις μονάδες είναι το decision engine όπου εμπεριέχονται υλοποιημένα τα μαθηματικά μοντέλα λήψης απόφασης με Bayesian networks. Η πλατφόρμα αυτή εκίνησε το ενδιαφέρον των συμμετεχόντων του συνεδρίου, διότι αφορούσε ένα πολύ φιλόδοξο δύσκολο και μεγάλο project της ΕΕ. Στο συνέδριο αυτό κληθήκαμε, από ένα καναδικό πανεπιστήμιο, όταν υλοποιηθεί οριστικά το σύστημα, να γράψουμε ένα κεφάλαιο που να περιγράφει τις αρχές του σε ένα βιβλίο με θέμα «Multi-Device User Interfaces»
“An Influence Diagram-Based Approach to Location Aware Mobile Computing” Proceedings of the “HCI International 2003”, 10th International Conference on Human - Computer Interaction, Crete, June 22-27, 2003. Abstract: The present paper discusses issues related to the demands of forthcoming location aware mobile computing. A design for building adaptive interfaces following the principles of Universal access is proposed as a proper and potential solution for the new technological challenges. Next, the paper recommends the use of influence diagrams (Bayesian decision networks) for nesting uncertainty, inherit in these novel user machine interactions. Motivation Πολύ ενδιαφέρον τα τελευταία χρόνια έχουν τα πληροφοριακά συστήματα, που θα μπορούν να υποστηρίξουν αλληλεπίδραση ενός χρήστη με μια υπολογιστική συσκευή, καθώς αυτός κινείται. Η αλληλεπίδραση αυτή καλείται mobile computing και στα επόμενα χρόνια θα αρχίσει να αποκτά μεγαλύτερη σημασία, καθώς οι νέες τεχνολογίες ασύρματων δικτύων και οι βελτιωμένες φορητές υπολογιστικές μονάδες, θα επιτρέψουν την ανάπτυξη χρήσιμων και δημοφιλών εφαρμογών. Novelty - Impact Στην εργασία αυτή, για πρώτη φορά διατυπώνεται και αποδεικνύεται με ένα παράδειγμα, ότι η αβεβαιότητα είναι εγγενής ιδιότητα των αλληλεπιδράσεων ανθρώπου μηχανής στο mobile computing και συνεπώς η κατασκευή μιας έξυπνης διεπαφής, σε αυτό το πεδίο, απαιτεί την χρήση μαθηματικού μοντέλου λήψης απόφασης με Bayesian reasoning. Στην συνέχεια η εργασία παρουσιάζει ένα γενικό μαθηματικό γράφο απόφασης με Bayesian nodes, που αναφέρεται στην περίπτωση του context aware mobile computing, δηλαδή σε αλληλεπίδραση με ένα σύστημα που ξέρει την θέση του χρήστη, μέσα σε ένα χώρο καθώς αυτός κινείται. 5. V. Zarikas, A. Christopoulos, V.L. Rendoumis “Volatility of a stock index as thermodynamic fluctuation” Proceedings of 7th International Conference on Applied Financial Economics, Samos, 1-3 July- 2010 Abstract: This paper describes a new empirical model that has been developed in order to encompass the phenomena of up and down trends and the related volatility of stock indices. The approach follows ideas established in the context of statistical thermodynamics. The model is based on the thermodynamic behaviour of a system in contact with reservoirs and it is capable to describe the macroscopic properties of stock markets. A novel inherent to the model phenomenological explanation is proposed for the descprition of the volatility of a stock index. The model encompasses a mechanism for the fluctuations of the stock market indices. Novelty – Impact Στην εργασία αυτή μελετούμε για πρώτη φορά τις μεταβολές ενός χρηματιστηριακού δείκτη βασισμένοι σε ένα μαθηματικό μοντέλο που προσεγγίζει με θερμοδυναμικό τρόπο τα εισοδήμα που ανταλλάσονται στις συναλλαγές. Ο ανάλογος της θερμοδυναμικής νόμος ψύξης και θέρμανσης βρίσκει εφαρμογή στη άνοδο ή στην κάθοδο ενός δείκτη. Επιπλέον όμως σε αυτή την εργασία αποδεικνύουμε ότι η volatility η οποία συνήθως περιγράφεται στοχαστικά μπορεί αβίαστα να περιγραφεί σαν θερμική διαταραχή γύρω από την μέση θερμοκρασία η οποία βέβαια μπορεί είτε να ανεβαίνει ή να μειώνεται με τον χρόνο. 6. Vasilios Zarikas, Kitsos C.P. , "Risk Analysis with Reference Class Forecasting adopting Tolerance Regions ", 5th International Conference on Risk Analysis, Tomar, Portugal; 06/2013 , 2013 Abstract: The target of this paper is to demonstrate the benefits of using tolerance regions statistics in risk analysis. In particular, adopting the expected beta content tolerance regions as an alternative approach for choosing the optimal order of a response polynomial it is possible to improve results in reference class forecasting methodology. Reference class forecasting tries to predict the result of a planned action based on actual outcomes in a reference class of similar actions to that being forecast. Scientists/analysts do not usually work with a best fitting polynomial according to a prediction criterion. The present paper proposes an algorithm, which selects the best response polynomial, as far as a future prediction is concerned for reference class forecasting. The computational approach adopted is discussed with the help of an example of a relevant application. Keywords: Risk analysis, Reference class forecasting, General Linear Regression, Predictive models, Tolerance regions. 7. V. L. Rendoumis, V. Zarikas “Can the Volatility of a stock index be described as a thermodynamic fluctuation?” 2ο ΠΑΝΕΛΛΗΝΙΟ ΣΥΝΕΔΡΙΟ ΕΦΑΡΜΟΣΜΕΝΗΣ ΟΙΚΟΝΟΜΙΚΗΣ 14 – 15 ΑΠΡΙΛΙΟΥ 2011, Βόλος, Πανεπιστήμιο Θεσσαλίας Abstract: Nowadays, the ideas and considerations about financial markets, economic phenomena and the behaviour of people involved in economic transactions undergo large changes. The contemporary view of economics and its need for more solid mathematical reasoning and theoretical manifestation led, a large number of physicists and other scientist from traditional quantitative fields, to study and analyse economic phenomena and data. One of the fundamental ideas behind this effort is; Economic phenomena are the macroscopic results of microscopic interaction among many agents. This micro-macro relation could be simulated by physical systems. Basic tools for the utilization of this formalism are, among others, complexity theory, statistical physics, thermodynamics and solid state physics. In this paper we will present a novel empirical model based on the principles of statistical thermodynamics. This approach has been developed in order to describe stock market trends and the related volatility. In order to describe macroscopic properties of stock markets we use the concept of thermal contact of a system with a heat reservoir. Moreover, we will introduce a new phenomenological explanation for the description of the volatility of a stock index and a mechanism for stock market fluctuations. Γ. ΔΗΜΟΣΙΕΥΣΕΙΣ ΣΕ ΕΠΙΣΤΗΜΟΝΙΚΑ ΣΥΝΕΔΡΙΑ ΜΕ ΠΕΡΙΟΔΙΚΟΤΗΤΑ και ΜΕ ΚΡΙΣΗ ΠΕΡΙΛΗΨΗΣ (Scientific Conferences with perioodicity)
“COSMOLOGICAL AND PHENOMENOLOGICAL STUDY OF STRINGY MODELS. Cosmic charge asymmetry from a superstring inspired Lagrangian” Workshop – Connecting Fundamental Physics and Cosmology, University of Cambridge, Isaac Newton Institute for Mathematical Sciences, 16 – 20 August and 22 - 27 August 1999. Abstract: Recently various string inspired models have gained a lot of interest not only because of the second string revolution but also because of the possibility to discover new physics with the future experiments at the 1 TeV scale. In the context of the two-Higgs extension of the SM, the charge violating cosmological phase does not produce a net charge asymmetry. However if the spectrum contains heavy leptons it is possible to create a net cosmic charge asymmetry. This asymmetry can lead to dramatic effects in the cosmological evolution due to the large strength of the electromagnetic interactions as compared to those of gravity. Any specific model that produces a charge asymmetry beyond a certain limit can be ruled out on cosmological grounds. 2. M.Koutsovasili, N. Papanikolaou, V. Zarikas, C. Kyritsi «Statistical analysis of accidents regarding the use of elevators in Greece» Proceedings of the International IAEE Conference on Vertical Transportation Technologies, (ELEVCON 2010), June 2 – 4, 2010, Lucerne, Switzerland, pp. 204 – 214. \
A statistical survey is being carried out by Lamia Institute of Technology research team, regarding accidents on elevators and escalators in Greece on the occasion of recent fatal accidents during past twelve years. The aim of this research is to provide the essential information needed to focus attention on certain crucial mistakes and misguided actions, in order to make the use of both lift and rolling stairs / corridors safer in the future. Results will help preventing similar accidents for the technical staff and the users, as well as designing and teaching a new culture and attitude from the users’ side. This work presents some first statistical outcomes and results from this analysis. Δ. ΜΟΝΟΓΡΑΦΙΕΣ, ΚΕΦΑΛΑΙΑ ΣΕ ΕΡΕΥΝΗΤΙΚΑ ΕΠΙΣΤΗΜΟΝΙΚΑ ΒΙΒΛΙΑ.
“User-, platform-, and location- adapted information services over the Web - The PALIO Framework for Adaptive Information Services.” Chapter in the book “Multi-Device User Interfaces: Engineering and Application Frameworks”. published by Wiley, 2004. with editors Ahmed Seffah and Homa Javahery, Computer Science Department, Faculty of Engineering and Computer Science, Concordia University, Quebec, Canada Abstract: In this chapter we describe the architecture of an information system that provides personalised provision of information to users through a variety of devices and networks and in a variety of different contexts of use. The design of the architecture is rooted on the concept of universal design, as it has evolved over the past decade. Universal design refers to the conscious effort to consider and take into account the widest possible range of end-user requirements throughout the development life-cycle of a product or service. The main motivation is the development of an open system for accessing and retrieving information without constraints and limitations (imposed by space, time, access technology, etc). Therefore, the system should be modular and capable of interoperating with other existing information systems. In this respect, mobile communication systems play an essential role, because they enable access to services from anywhere and at anytime. An example is the support of a wide range of communication technologies (mobile or wired) to access services. In particular, it will be possible for a user, who is equipped either with a common cellular phone or an advanced WAP phone, to access services from any place. Motivation Ένα από τα πιο σημαντικά ζητούμενα στην σύγχρονη πληροφορική, είναι η ανάπτυξη έξυπνων πληροφοριακών συστημάτων, που να βασίζονται σε σύγχρονα μαθηματικά μοντέλα λήψης απόφασης, ώστε να έχουν την ιδιότητα να προσαρμόζονται δυναμικά στις ιδιαίτερες συνθήκες του περιβάλλοντος, στις ιδιαίτερες ανάγκες του χρήστη στο είδος της πληροφορίας και στο είδος της συσκευής με την οποία ο χρήστης αλληλεπιδρά με το σύστημα. Εύκολα γίνεται αντιληπτό πόσο δύσκολο είναι να επιτευχθεί ένας τέτοιος συγκερασμός. Novelty – Impact To PALIO framework αποτελεί ένα από τα πιο σύνθετα και σύγχρονα πρότυπα αυτοπροσαρμόσιμα πληροφοριακά συστήματα, που έχουν υλοποιηθεί. Αποτελεί μάλιστα πλατφόρμα για την ανάπτυξη domain dependent περιεχομένου (περιεχόμενο που περιγράφεται σε XML και αφορά ένα συγκεκριμένο θέμα π.χ. τουριστική πληροφορία για την Αθήνα, πληροφορία για τα προσανατολισμό κλπ). Δεν είναι υλοποιημένο το σύστημα, δηλαδή για ένα μόνο συγκεκριμένο θέμα. To decision engine του PALIO περιλαμβάνει και αλγόριθμους, που υλοποιούν δένδρα αποφάσεων, που μπορούν να ενσωματώνουν γνώση με αβεβαιότητα. Αυτά είναι τα λεγόμενα decision graphs με bayesian networks που χρησιμοποιούνται για αποφάσεις και διαγνώσεις. Το κεφάλαιο αυτό περιγράφει το συνολικό σύστημα και τις τεχνικές υλοποίησης.
Ε. ΤΕΧΝΙΚΕΣ ΑΝΑΦΟΡΕΣ Είμαι συγγραφέας πολλών τεχνικών αναφορών στα κάτωθι θέματα
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