Publications by Type: Conference Paper

We study the magnetization, M, and the spin polarization, ζ, of n-doped non-magnetic-semiconductor (NMS)/narrow to wide dilute-magnetic-semiconductor (DMS)/n-doped NMS quantum wells, as a function of the temperature, T, and the in-plane magnetic field, B. Under such conditions the density of states (DOS) deviates from the occasionally stereotypic step-like form, both quantitatively and qualitatively. The DOS modification causes an impressive fluctuation of M in cases of vigorous competition between spatial and magnetic confinement. At low T, the enhanced electron spin-splitting, Uoσ, acquires its bigger value. At higher T, Uoσ decreases, augmenting the influence of the spin-up electrons. Increasing B, Uoσ increases and accordingly electrons populate spin-down subbands while they abandon spin-up subbands. Furthermore, due to the DOS modification, all energetically higher subbands become gradually depopulated.

This paper describes the study of the structural control of the Meganissi island coastal zone and its geomorphological evolution; based on that it detects and presents coastal hazard. The coastal geomorphology is affected by the lithological configuration, the tectonism, the wider seismotectonic status and the sea activity. For this study, a database has been structured in G.I.S. was using all data deriving from the above characteristics as well as detailed fieldwork, aerial photos, satellite images and pre-existing maps. Data were analysed and processed in order to locate zones of high hazard risk. Finally, a hazard risk map was developed for Meganissi island.

We investigate the magnetization of II–VI non‐magnetic‐semiconductor (NMS) / narrow to wide dilute‐magnetic‐semiconductor (DMS) / NMS quantum wells. These structures are appropriate for conduction‐band spintronics. We employ an in‐plane magnetic field, B, in order to induce non‐step‐like density of states. Finally, we tune the spin polarization by varying the temperature, T, and B, i.e. we investigate the magnetic phases of these NMS/DMS/NMS structures.

We investigate generalized asymmetric left-handed (LH) slab waveguides that constitute an extension to the symmetric structure initially proposed by Pendry. By utilizing the asymmetry it has been shown that they have the potential for increased image resolution. This is due to the amplification of the formed surface waves (SWs) that is able to compensate material losses. Some preliminary studies in this direction have been reported in the literature but, to the best of our knowledge, there is no complete study of all possible S W eigenmodes supported by such LH waveguides. A rigorous theoretical investigation is presented herein that offers clear mathematical explanation and detailed physical insight into the formation of surface polaritons (SPs) in these heterostructures and provides the conditions for their existence. It is found that a rich variety of SP modes can exist (30 in total) that depend critically on the combination of the different refractive indices, constitutive parameters ε(ω) and μ(ω) the sample geometry. For each case we provide the geometric dispersion diagram and the profile of the corresponding stable field configuration from which the various characteristics of the mode (enhancement, phase reversal) are apparent, An interesting result of the above analysis is that, for certain choices of the material parameters, the coupling between the interfaces allows the existence of new 'supermodes' when no stable solutions exist at the isolated interfaces of the slab alone. Finally, the modes that give rise to negative group velocity are identified and key features of the dispersion diagrams are discussed, most of which are unique to the structures studied herein and have not been previously recovered with symmetrical studies.

Published in CORDIS March 2006 http://cordis.europa.eu.int/ist/directorate g/seminar20060405.htm (Η εισήγηση (position paper και action plan) της κα. Καμπερίδου ως μέλος του GEAG  συμπεριλήφθηκαν στους ατομικούς φακέλους/ντοσιέ των συμμετεχόντων και στις συζητήσεις. Στη συνέχεια ακολούθησε και δημοσίευση στο Cordis: http://cordis.europa.eu.int/ist/directorate g/seminar20060405.htm)--- **(Kamberidou, I., & Patsantaras, N. (2005). 'Towards a Gender-Neutral Inclusive Information Society: Preserving the European Model in the Information Age'. Women in Science Seminar: Women in the Information Society, European Commission Information Society and Media Directorate-General, Brussels (pp. 1–11), Brussels (DOI: 10.13140/RG.2.1.4646.0962). Published in Cordis: http://cordis.europa.eu.int/ist/directorate g/seminar20060405.htm.Abstract http://scholar.uoa.gr/sites/default/files/ikamper/files/towards_a_gender_neutral_inclusive_information_society.pdf   [ L. in Apella]

1. Position Paper-action plan distributed in folders of all the participants at the Women in the Information Society Seminar: Women in the Information Society, European Commission Information Society and Media Directorate-General, 5/4/2005, Centre Borschette, rue Froissart 36-1049, Brussels.
2. Participation as member of the Gender Expert Action Group (GEAG) of the European Commission DG for Information Society and Media [ L.1.  in Apella]

• Η εισήγηση (position paper και action plan) της κα. Καμπερίδου ως μέλος του GEAG (εμπειρογνώμων για θέματα φύλου και ισότητας) συμπεριλήφθηκαν στους ατομικούς φακέλους/ντοσιέ των συμμετεχόντων και στις συζητήσεις. Στη συνέχεια ακολούθησε και η δημοσίευση στο Cordis: http://cordis.europa.eu.int/ist/directorate g/seminar20060405.htm)  DOI: 10.13140/RG.2.1.4646.0962

In this paper the counteractive dynamic marine and river environments responsible for a river mouth’s and a delta’s modulation is studied. The Acheloos River (West Greece) was chosen as the case study due to the recent changes taken place in its basin. The aim of this study is to analyze the present dominant environment and the impact of human activity on this balance. A GIS database was developed and updated in order to provide access for future use and computer analysis (both spatial and chronological). The study, includes an estimation of the delta forming processes, the impact of the anthropogenic parameters on these processes, and, finally, their representation.

Kamberidou, Irene & Patsantaras, Nikolaos (2005). Virtual Globalization. Paper and proposals as member of GEAG and Research Group for the Consultation Workshop on Gender and Technology, European Commission, Information Society Directorate-General Miniaturisation, Embedded Systems, Societal Applications, April 22, 2005 Brussels.-------------------------------------------------------------------------------------------------------- RESEARCH GROUP PAPER AND DRAFT PROPOSALS FOR CONSULTATION WORKSHOP ON GENDER AND TECHNOLOGY, BRUSSELS, EUROPEAN COMMISSION, Information Society Directorate-General Miniaturisation, Embedded Systems, Societal Applications , February 12, 2005. Includes Irene Kamberidou's Paper and proposals as member of the Gender Expert Action Group (GEAG) and the Research Group for the next Consultation Workshop on Gender and Technology, European Commission, Information Society Directorate-General Miniaturisation, Embedded Systems, Societal Applications, April 22, 2005 Brussels (DOI: 10.13140/RG.2.1.3546.7606). Concludes with Irene Kamberidou’s observations and proposals from last Gender & Technology Workshop in Brussels.   Keywords and future directions: Bodiless society, gender-neutral society, gender subject, service society, virtual servitude, information manipulation, electronic surveillance, electronic terrorism, (new) information world order, digital despotism, digital capitalism, information elite, exclusionist technophobia, digital illiteracy, interdisciplinary communication, education, techno-education, integration of women (gender integration), action plan, techno-ethos, techno-ethics.   Everything as we know it today is definitively and ultimately in the process of transformation due to two significant changes in the global scene—the globalization of the economy, aggressive/dynamic competition, and the ‘invasion’ of technology in every area of human-social life, in every sector of public and private activity. Today we are witnessing the creation of “a society of services/ a service society”, as a result of accelerated technological developments, in combination with the globalization of the economy-- a service society, ‘a bodiless society” which is gradually replacing industrial society. The expansion of a new bureaucracy is being promoted, the formulation of units that provide services, and the creation of thousands of specialized employment positions in the distribution and use of new technologies, whose hard nucleus is made up of specific specialized knowledge and know-how, denied to the less-privileged gender subject/citizen. The products of the technological revolution are in reality services—a fact that has foundational consequences on society! We are at a transitional stage, in a transitional period that not only disorganizes and disorientates but also marginalizes the less privileged gender subject, namely an extremely large sector of the population, the majority of the EU population, the non-mainstream social groups. That which was familiar, understood and considered a given is being eradicated, and no longer understood. Due to the high speed disorganization of existing structures the gender subject/citizen is having dramatic difficulty in adapting and comprehending what is going on, and our social system is confronting difficulties in defining the problems and thus providing solutions on how we can get through this transitional period. KEYWORDS: Gender subject/citizen, service society, commercialization, “professionalization”, virtual world order, virtual servitude, digital despotism, virtual elite, future exclusions-technophobia, cultural commonality, commonality of cultures, virtual illiteracy, virtual techno-illiteracy, interdisciplinary communication/research, Education, socio-economic-biocentric rationale, technoethics – technoethos https://pergamos.lib.uoa.gr/uoa/dl/object/2775578  

• Includes Irene Kamberidou’s observations / proposals from last workshop. 
• GEAG (Gender Action Group)

The goal is to visualize a set of multivariate data in such a way that datavectors belonging to different classes (subgroups) appear differentiated as muchas possible. When intending such visualization, the first question should be aboutthe intrinsic dimensionality of the data. The answer may be obtained byevaluating, e.g., the fractal correlation dimension. The projection to a plane isjustified when the correlation dimension of the data is about 2. Only in such casethe performed visualization is plausible to reflect all the between group and thewithin group relationships among the data vectors. There are several recognizedmethods for mapping data to a plane. Our interest lies especially in nonlinearmethods. We consider in detail three methods: The canonical discriminantfunctions, the kernel discriminant functions and the neuroscale mapping. Weillustrate our considerations using the Kefallinia erosion data, where each datavector belongs - in a crisp way – to one of five predefined subgroups indicatingthe severity of the erosion risk. The assignments to the subgroups were performedby an expert GIS system based on logical rules established by experts.

Kamberidou, Irene & Patsantaras, Nikolaos (2004). "Absolute Exclusion: Today’s Digital Exiles”.  Analysis Report, presentation as member of GEAG for the Gender eQuality Session, second Consultation Workshop on Gender and Technology, European Commission, Information Society Directorate-General Miniaturisation, Embedded Systems, Societal Applications, Oct. 15, 2004 Brussels.   **Includes Technoethics proposals and final Report on the Gender Workshop of October 15, 2004, list of participants, membership in Expert working group, inclusion/invitation to next meeting Jan. 2005 and letter of appreciation. ** member of GEAG-Gender Expert Action Group 

The main purpose of this paper, is to study the coastal morphology of the five largest islands in the Ionian Sea (Zante, Kefallinia, Ithaki, Leukas, Corfu) located in Western Greece, in relation to lithology, tectonic characteristics, general seismotectonic regime and marine processes of the area, and finally to locate sites of possible future coastal retreat. The predominant lithological formation of the coasts of Zante, Kefallinia, Ithaki and Leukas, is the carbonate rocks. The shores of Corfu island are composed mainly of Neogene and Quaternary formations. The morphology of the steep coastline is determined in general by offshore normal faults having NW-SE and N-S directions and the relief steepness is intensified by the high resistivity of the calcareous formations. The low relief coasts are common in areas where Quaternary deposits are dominant. Data derived from aerial and satellite images, large scale maps and detailed fieldwork mapping were treated by GIS. The upper coastal zone limit was extended up to the 20m contour line. A coastal hazard map was developed focusing on erosion prone areas. The most vulnerable were found to be the western coasts of Leukas, south Kefallinia, north Ithaki and north Corfu. Landslides and rockfalls are especially risky in western Leukas, northern Corfu and southernKefallinia.

In this paper the area of the lakes Iliki and Paralimni are examined (Viotia). The research focuses on the influence of the tectonic on the morphological structure of the area and on the formation of the lakes, with fieldwork and the use of GIS (Geographic Information Systems). For this purpose the azimuth directions ofthe rupture zones were calculated with the use of ‘geoline orientation’ algorithm. The analysis of the morphological slopes and of the aspect was performed with the use of the algorithm ‘Triangulation with smoothing’. The outcome of the fault direction concurs with the Pliocene faults direction, as well as the tectonic Fokiko - Viotiko trough direction. The Quaternary faults direction concurs with the recent rupturezone. In general, the dominating morphological slopes are of 0-10%, while the higher slopes are found at the north and east. The aspect that concerns the direction of the morphological slope concurs with the main rupture zone of the tectonic Fokiko - Viotiko trough direction, and the recent rupture zone. The orientation of Iliki lake corresponds to the former rupture zone; the orientation of Paralimni lake corresponds to the later one.

The development and application of a three-dimensional finite-difference time-domain (FDTD) model for a travelingwave heterojunction phototransistor (TW-HPT) are presented. The model is enhanced using effective permittivity schemes at the dielectric interfaces and special techniques for the treatment of very thin material sheets. The 3D fullwave electgromagnetic model allows the numerical calculation of the output photocurrent, electrical characteristic impedance, light absorption, microwave losses as well as microwave and optical dispersion. Run in a fast, parallel processing, machine the simulation herein allowed (for the first time, to the best of the authors' knowledge) the simultaneous investigation of the optical and microwave characteristics of the traveling-wave structure. This is in contrast to the approach followed by other researchers in the past, as well as by popular simulation packages, based on which results only for the microwave property can be obtained. Snapshots of the field propagation inside the device provide valuable insight into its passive behavior and clearly demonstrate the device's velocity mismatch between the optical signal and the photogenerated electrical pulse. Numerical results for the effective refractive indices of the optical and electrical wave quantify the difference in the velocities of the two waves.

Καμπερίδου, Ειρήνη (2004). «Το Έμφυλο [υποκείμενο] και Ολυμπισμός». (Gender and Olympism) Εισήγηση στο 8ο Πανελλήνιου Συνέδριο Πτυχιούχων Φυσικής Αγωγής & Αθλητισμού (ΠΕΠΦΑ), [περίληψη στα πρακτικά τoυ συνεδρίου]  7-9 Μαίου 2004, Αθήνα. [M in Apella]  

• Kamberidou, I. (2004). Gender and Olympism [in Greek]. Presentation at the 8th Panhellenic Conference of the Graduates of Physical Ed. and Sport (PEPFA), 7-9 May 2004, Athens Greece. PEPFA  [M in Apella]

We demonstrate that hydromagnetic acceleration can be the driving mechanism of outflows in GRB sources. Using semianalytical solutions of the full set of the steady, axisymmetric, ideal hydromagnetic equations in flat spacetime -- i.e., solving the momentum equation along the flow as well as in the transfield direction -- we model the acceleration of the baryon/e±/photon fluid that emanates from a stellar-mass compact object/debris-disk system. We prove that for highly relativistic, multiple-shell outflows one can study the motion of each shell using steady-state equations. Employing a radially self-similar model, we find that the flow is initially thermally and subsequently magnetically accelerated. The Lorentz force is capable of transferring close to a half of the total energy of an initially Poynting-dominated flow to baryonic kinetic energy.

Using ideal magnetohydrodynamics we examine an outflow from a disk surrounding a stellar-mass compact object. We demonstrate that the magnetic acceleration is efficient (>~ 50% of the magnetic energy can be transformed into kinetic energy of γ > 102 baryons) and also that the jet becomes collimated to very small opening angles. Observational implications, focusing on the case of an initially neutron-rich outflow, are discussed in Königl's contribution.

Using ideal magnetohydrodynamics we examine an outflow from a disk surrounding a stellar-mass compact object. We demonstrate that the magnetic acceleration is efficient (>~ 50% of the magnetic energy can be transformed into kinetic energy of γ > 102 baryons) and also that the jet becomes collimated to very small opening angles. Observational implications, focusing on the case of an initially neutron-rich outflow, are discussed in Königl's contribution.

During two observational seasons of international campaign of YY Her we secured photometric data which covered the primary as well as the secondary minima and revealed unexpected outburst activity of this system.

This paper reports new photometric observations of minima of two very long-period eclipsing systems: AZ Cas (P=3402 °}) and EE Cep (P=2050 °). In order to match the observed depth of the primary minimum of AZ Cas we had to introduce a third light component. For EE Cep, the shape of the eclipse can be explained by a model that includes a dark precessing disk in the system.

The regions around the doubly magic nuclei 100Sn and 78Ni are of great interest from a nuclear structure standpoint. These nuclei also play a key role in the astrophysical rp- and r-processes, respectively. Recently, nuclei in these regions were studied at the Coupled Cyclotron Facility at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University.

There are observational indications that relativistic outflows in AGNs are accelerated over distances that far exceed the scale of the central engine. Examples include the radio galaxy NGC 6251, where knots in the radio jets were inferred to accelerate from ∼0.13 c at a distance of ∼0.53 pc from the galactic nucleus to ∼0.42 c at r=1.0 pc, and the quasar 3C 345, where the Lorentz factor of the radio knot C7 was deduced to increase from ∼ 5 to >10 as it moved from r=3 pc to r=20 pc}. It is argued, using exact semianalytic solutions of the relativistic MHD equations, that this behavior is a signature of magnetic acceleration. The same basic driving mechanism may apply to the relativistic jets in AGNs, gamma-ray burst sources, and microquasars.

There are observational indications that relativistic outflows in AGNs are accelerated over distances that far exceed the scale of the central engine. Examples include the radio galaxy NGC 6251, where knots in the radio jets were inferred to accelerate from ∼0.13 c at a distance of ∼0.53 pc from the galactic nucleus to ∼0.42 c at r=1.0 pc, and the quasar 3C 345, where the Lorentz factor of the radio knot C7 was deduced to increase from ∼ 5 to >10 as it moved from r=3 pc to r=20 pc}. It is argued, using exact semianalytic solutions of the relativistic MHD equations, that this behavior is a signature of magnetic acceleration. The same basic driving mechanism may apply to the relativistic jets in AGNs, gamma-ray burst sources, and microquasars.

Kamberidou, I. (2004).  “Slavery of the Mind and “Mental Imprisonment” (1870) in the harem: the Bodiless Society, a de-gendered or gender-neutral emancipatory social space? Opening presentation  (10.30 -11.00) to the ‘Virtual Harem’ for the Consultation Workshop on Gender and Technology, European Commission – Information Society DG. Avenue de Beaulieu 31   6/30, 1160 Brussels, 28 June 2004    [explanation of power structures, limits and lessons that can be drawn]   M. 1.  in Apella,

• Includes Consultation Workshop on Gender and Technology report on presentations, along with Preliminary Agenda/first draft (before corrections) for Gender and Technology Consultation Workshop, European Commission, Brussels 

Patsantaras, N. & Kamberidou, I. (2004). Technoethics-Technoethos. Second study presented [and submitted] at the Consultation Workshop on Gender and Technology in Brussels, 28 June 2004, Venue: European Commission, Information Society Directorate-General Miniaturisation, Embedded Systems, Societal Applications, June 28, 2004, Brussels. ***

• Also included, Consultation Workshop on Gender and Technology revised report,  along with our draft Policy Proposal on GENDER AND THE INFORMATION SOCIETY, July 2004.

In this paper we will discuss current research on the synthesis of the singing voice, its technical problems and esthetic issues, and the perspective of creating a vocal synthesizer which could be accessible to composers, musicians and musicologists, as a creative tool for composing, performing, and interpreting forgotten voice techniques of various cultures and bygone times.

Kamberidou, I., & Patsantaras, N. (2004).  The “Virtual Harem”: Technophobia or Exclusion? An Educational Perspective. Study presented (and submitted) at the Consultation Workshop on Gender and Technology, 28 June 2004, Venue: European Commission – Information Society DG. Avenue de Beaulieu 31   6/30, 1160 Brussels. **Includes. Gender and Technology Workshop first draft report on presentation  

The dispersion characteristics and the field distributions for all kind of waves which can propagate in surface corrugated waveguides are calculated by a method based on the Floquet theorem. Numerical results are presented for several corrugated structures with rectangular and circular cross-section and a comparison is made with already established codes.

We use exact self-similar solutions of the steady, axisymmetric, relativistic, hydromagnetic equations to study the formation of AGN jets. Our formalism allows us to examine the effects of the thermal, centrifugal, and electromagnetic forces on the flow acceleration and collimation. We apply our analysis to the jet in NGC 6251 and show that the puzzling sub-pc scale acceleration to mildly relativistic speeds recently inferred in this source from VLBI measurements can be attributed to magnetic driving.

We present a study of bright X-ray sources in the central part of the Small Magellanic Cloud based on a survey performed with the Chandra X-ray Observatory (see accompanying poster by J. McDowell et al). From the 122 sources (at the 3σ level), detected within the 1280 arcmin2 covered by the survey, we concentrate on the 16 brightest sources (>100 counts; LX > 1035erg/s) for which we can perform detailed spectral and timing analysis. These sources include two known supernova remnants (in one of which we identify a weak central point-like source), seven known X-ray binaries, and five previously detected sources which are most likely pulsar binaries, based on spectra and variability from the Chandra data. Two sources were not detected by any previous scans and are new transient candidate X-ray binary pulsars. This work was supported in part by the SAO intern program under NSF grant AST-9731923 and in part by NASA Grant G02-3117X.

We present preliminary results from our Cycle 3 Chandra survey of the central region of the Small Magellanic Cloud. Five ACIS-I fields cover a large fraction of the bar. The images show at least ten bright, extended, supernova remnants and two bright, previously unknown, transients; point sources are detected down to a luminosity of log L(erg/s) = 33. We have obtained exposure-corrected luminosity functions for each field.

We summarize the early results from a Chandra X-ray Observatory survey of the central region of the Small Magellanic Cloud, dominated by a recent burst of star formation. We detect 122 sources in five ACIS fields, reaching a 0.1-10 keV luminosity (corrected for Milky Way absorption ) of 4.3× 1033 erg/s, an order of magnitude deeper than previous surveys. Our survey includes 20 candidate transient sources and measures extent in 5 supernova remnants. The data indicate fewer very faint sources than would be expected from the background. We compare our results with ROSAT and ASCA observations of the region; many of the ASCA sources are found to suffer from confusion. We are beginning a program of optical identifications for the newly discovered sources. The companion poster by Taylor et al. describes our X-ray spectral and timing analysis on the bright sources. We acknowledge support from the Chandra X-ray Center (NASA contract NAS8-39073).

We compare space quantization obtained by codebook vectors yielded by Kohonen’s self-organizing maps and the neural gas methods. The average approximation error (called also the quantization error) is smaller when applying the neural gas method. The results are visualized graphically by scatterplot matrices. For the special case of 3-dimensional data the results, i.e. location of the representative codebook vectors among the original data points – are also visualized by a rotatable 3-D plot. The analysis was carried out for the Kefallinia data counting n D 3420 data vectors, each with p D 3 components. We stated that the results depend on the way of standardization of the data.

We consider a large set of data comprising N=3422 data vectors, each containing observations on p=3 variables. We find for these data representative data vectors. We do it by employing the methodology of Kohonen's self-organizing maps. The found representative data vectors are called codebook vectors. In particular we analyze two collections (assemblages) of codebook vectors counting m=275 and m=120 elements. The quantity of the representation is measured by evaluating two errors: the quantization error q1 and the topological error q2. We show for our data that the magnitude of these errors depends on the way the original data werestandardized. After a thorough graphical analysis of the results we came to the conclusion that codebook vectors obtained from data standardized by range yield a little better representation as those do which were obtained from data standardized by variance. None of the representations is satisfactory from our point of view.

In this paper the area of Iliki and Paralimni karstic lakes is studied throughfieldwork and GIS. The study area is situated east of the Fokida – Beotia tectonicdepression focusing on the relation of the tectonic activity to the formation of thesurrounding slopes. As a result of this study, slope formation is related to the two main tectonic phases of the wider area.

We report the results of the second large campaign of photometric observations for the small-amplitude delta Scuti star GSC 4778-00324, detected in the course of a multi-site campaign aiming at monitoring V1162 Ori. We confirm the presence of the same two frequencies as found in the first analysis based on the 2000-2001 data.

In this paper we examine methods of digital image processing, in order to extract drainage system branches and import them into a GIS layer. Moreover, we have developed special algorithms on GIS environment in order to analyse drainage system parameters. In order to get the optimum detection of the drainage system characteristics, we applied on the Landsat image and on aerial photos several filters. Using the aerial photos of the area, we created the orthophotomosaic, which came out of the ortho-rectified aerial photos. Via stereoscopic observation on the computer screen, we detected and digitized the drainage system branches. Using special algorithms, developed under the MapBasic programming language, we evaluated the drainage system and the faults directions, in order to analyse them quantitatively and geographically.

Using relativistic, axisymmetric, ideal MHD, we examine the outflow from a debris disk around a newly formed stellar-mass black hole, taking into account the baryonic matter, the electron-positron/photon fluid, and the large-scale electromagnetic field. We clarify the relationship between the thermal (fireball) and magnetic (Poynting flux) acceleration mechanisms, identify the parameter regimes where qualitatively different behaviors are expected, and demonstrate that the observationally inferred properties of the GRB outflows can be attributed to magnetic driving. We show that the Lorentz force can convert up to 50% of the initial total energy into kinetic energy of a collimated flow of baryons. This energy, in turn, may be converted into radiation by internal shocks. We examine how baryon loading and magnetic collimation affect the structure of the flow.

Using relativistic, axisymmetric, ideal MHD, we examine the outflow from a debris disk around a newly formed stellar-mass black hole, taking into account the baryonic matter, the electron-positron/photon fluid, and the large-scale electromagnetic field. We clarify the relationship between the thermal (fireball) and magnetic (Poynting flux) acceleration mechanisms, identify the parameter regimes where qualitatively different behaviors are expected, and demonstrate that the observationally inferred properties of the GRB outflows can be attributed to magnetic driving. We show that the Lorentz force can convert up to 50% of the initial total energy into kinetic energy of a collimated flow of baryons. This energy, in turn, may be converted into radiation by internal shocks. We examine how baryon loading and magnetic collimation affect the structure of the flow.

Recent highlights of our study of positive and negative superhumps in cataclysmic varibles are briefly reviewed. The ``genuine" superhumps have been detected a day after the unexpected superoutburst of WZ Sge, when the orbital variability dominated the light curve. TT Ari has shown an unprecedented switch form the usual negative superhump state to the positive state with an excellent coincidence between the observed and theoretically predicted period values. Both stars show evidence for variability at a time scale of 20 minutes. The superhump period of RZ LMi has been corrected based on the observations of the superoutburst in 2001. ES Dra shows no evidence for prominent superhumps, possibly indicationg its low inclination. However, the superoutburst has shown a splitted maximum with a separation of 20 days. The ``superhump period-luminosity" dependence has been detected for two cataclysmic variables of different types -- the nova-like BZ Cam and the UG SU star V368 Peg.

The geomorphology of Greece is the result of multiphase tectonic movements of compressional and extensional nature plus exogenous processes. In this complex relief a Mediterranean-type ecosystem has been developed reflecting the prevailing climatic conditions. The frequent occurrence, especially during summer, of strong winds and high temperatures are the main reasons for extensive fires. The aim of this paper is to develop a methodology to face with this increasing danger using fuzzy set theory in a Web-GIS platform. As a case study of this work the two of the Ionian islands, Zakynthos and Kefallinia have been chosen, which are characterized by a relatively well developed vegetative cover and frequently recurring fires. It is widely accepted that the fire management is of primary importance for the environmental protection and planning.

In this paper we are examining Salamina island from a physical-geographical anda geomorphological aspect. For the purposes of this study, we used all existed official maps, recent aerial photographs and satellite image as well as data deriving from extensive fieldwork at the study area. The results of the photo-interpretence are combined and correlated with the outcome of the primary data (physical, geological, geomorphological) that were collected through fieldwork, which took place with the use of GPS, to ensure the accuracy of the measurements. This study resulted to the creation of a geomorphological map of the study area in a GIS environment, along with several thematic maps presenting all collected data (primary and secondary). Finally, a geomorphological and environmental evolution of the study area has taken place, in order to map the genesis of the nowadays morphology.

The main purpose of this paper, is to study the geomorphological evolution of Meganisi island’s coastal zone and to detect areas vulnerable to coastal erosion.The geomorphology of the island is effected by the lithological configuration, the tectonic characteristics, the wider seismotectonic status and the sea activity of the area. The wider area is characterized by intense seismicity: strong earthquakes are very frequent (M>6) and from the seismotectonic point of view is very complex. Limestone is the main lithological formation of Meganisi coastal zone. Coastline is steep and straight with morphological slopes ranging from 0%-66%. A big part of the area (40,87%) is of high slope (>20%). A GIS was developed using data deriving from detailed inland and sea fieldwork, aerial photos, satellite images and pre existing maps. Data were analysed statistically and geographically and variousthematic maps were created such as the morphological map, map of vulnerability, etc. Data deriving from this analysis as well as from fieldwork were processed through logical rules in order to locate zones of high erosion risk. Finally, an erosion risk map was developed in order to locate those areas that are vulnerable to futureerosion and to keep attention to them.

Optical Interferometry can play an important role in modern astronomy. Extrasolar planet and binary star research, are some of the fields, where we will face important discoveries in the future. For the VLTI this will be a real challenge, since it will be the pioneer in angular resolution. In addition, high flux sensitivity will help detecting not only Jupiter-sized planets, but Earth-sized planets too. The ability of the VLTI in detecting new planets, measuring stellar diameters and stellar proper motions, with the use of such techniques, is presented.

The first complete I-filter light curve of the eclipsing sdB binary HS 0705+6700 is analyzed using the Wilson-Devinney code and new geometric and photometric elements are derived. Using these elements together with the available spectroscopic data, it was possible to build a detailed model of the system. Our results are in good agreement with those found from photometric studies in other bands.

Coastal areas are the result of a complex interaction of many factors such as rock properties, geomorphological processes and wave action. We approach these dynamic landscapes using fuzzy set theory. As input variables we use rock’s erodibility, slope gradient, (drainage density,) vegetation and land use and wave characteristics. Next we formulate fuzzy logical rules to transform input variables to output ones. The output of the system represents the coastal depositional and erosional processes. As a case study we choose the island of Corfu (Greece) which presents lithologies very vulnerable to erosion and receives very high amount of rainfalls, in relation to the rest of the Greek territory. All this procedure has been developed using a loose coupling system of a flexible GIS platform and the proper environment to process fuzzy variables.

This study is dealing with the natural environment of the coastal zone of Paros island chosen as a representative ‘sample’ of the Cyclades complex of islands and amongst the most touristic ones. More than 75% of the coastal zone consists of high and lower cliffs, whilst relatively flat (slopes <2,5%) coastal plains do not exceed the 17% of the coastline. The island receives a considerable amount of wave energy; this has its highest values (>1500 W/m) at the NE part of the island and its lowest at the SE “protected” and shallower shelf area. Touristic (sandy/pebble) beaches have been developed along those parts of the coastline characterized by Quaternary (erodible) lithology associated with moderate wave activity. Sea level rise during the Holocene has played also an important role in coastal geomorphology; for example, Paros was connected to Naxos and Antiparos islands 10.000 yr BP and to Antiparos 6000 yr BP. A further rise of sea level (some 0,5 m at the year 2100) due to climatic changes will obviously deteriorate the terrestrial part of the coastal environment and especially all the touristic beaches and related establishments along its coastline.

In this paper we are going to develop group replacement policies for a service system by considering the number of customers dynamically in the queue. We consider a service system with multiple independent servers operating in parallel and a single queue. Customers arrive in accordance with a Poisson process, and the service time for each customer follows an exponential distribution. The servers are unreliable with identically exponentially distributed failure times and the repair time is assumed negligible. We formulate this model as a continuous time Markov decision process, and prove the optimal group replacement policy has a threshold structure.

Kamberidou, Irene  (2002). Dance and Physical Activity as a Symbol of Social Inferiority in the Ottoman Empire.  Proceedings of the 7th Annual Congress of the European College of Sport Science. Editors Maria Koskolou, Nickos Geladas, Vassilis Klissouras, Volume 2, Athens, 24-28 July, 2002 (S659/p. 577).[1] [1] Συμμετείχα στο συνέδριο, που οργανώθηκε από την Ελληνική Εταιρεία Αθλητικής Επιστήμης (ΕλΕΑΘλΕ) στην Αθήνα: ως (1) Μoderator στην έναρξη του συνεδρίου, (2) προεδρεύων στο session “Ethics in Sport” και (3) με δύο ανακοινώσεις, σε δύο sessions.

This paper is a preliminary study of an extensive project that will take place at Corfu island (Northern island of Ionian Sea), involving the municipality of Esperion and the Remote Sensing Laboratory (University of Athens). The project’s purpose is to estimate the erosion progress at Sidari bay’s (North part of Corfu island) coastal zone, due to wave activity. Sidari area consists of Neogene formations, which are extremely vulnerable. Moreover, wave impact is also of high energy, causing subsidence of the coastal line. Through this project, our team is developing a GIS database that holds information, deriving from existing maps, bibliographical references, and climatological logs, related to geology, geomorphology and environmental parameters. Apart from those data, aerial photography stereo observation and extensive D-GPS fieldwork resulted to continual coastline monitoring and GIS database updating, for a period of 26 and 5 years, respectively.Project’s conclusions are based on quantitative and spatial analysis through GIS, giving answers on the erosion’s rate, the erosion’s impact on human activities and structures, and finally an estimation on Sidari’s coastal zone future morphology.

Naxos is the largest island (430km2) οf Cyclades complex. The relief of the island is mountainous, with a central mountain chain crossing it from the north to the south.The geology of Naxos is characterized by a migmatite irruption, metamorphic rocks (schist, gneiss, marble), and sedimentary rocks (Neogenic and Quaternary deposits). Erosion is a complex procedure, which takes place after the forming ofweathered surface material. In this study, an erosion risk map was created, with the use of GIS technology. For this purpose, the maps and fieldwork data concerning the geology of the island, as well as the topography and the geomorphology (of the area) were imported into the GIS. Subsequently, the input data of the final thematicmap were modified with the use of fuzzy logic rules, which was considered to benecessary because of the nature of the studied variables.

In this study we examined the geomorphological and environmental characteristics of south Attika coastal zone (from Voula area to Lagonisi), a region in which man-made influence is very intense. This paper includes the detection of features of the coastal zone, that are in danger of alteration, because of their exposure to human intervention; it results to the study of the above characteristics and their mapping, with a purpose of using the final thematic maps in future study of the area, after the oncoming changes, because of the Olympic games of 2004. For this purpose we developed a database with geographical, geological, geomorphological and environmental characteristics in GIS and we created the corresponding thematic maps. Data collection took place through photointerpretation of corresponding aerial photos and fieldwork of the coastal zone (from inland and offshore) with the use of GPS.

The flat terrestrial part of the coastal zone of the Paros Island (slope <2,5% forelevations 0-50 m), represents only the 19% of the total area of the island (193 km2). More than 75% of the coastal zone consists of high and lower cliffs, whilst relatively flat and sandy (and/or pebble) beaches do not exceed the 17% of the coastline. The island receives a considerable amount of wave energy; this has its highest values (>1500 W/m) at the NE part of the island and its lowest at the SE “protected” and shallower area. Touristic (sandy/pebble) beaches have been developed along those parts of the coastline that characterized by vulnerable lithology associated with moderate wave activity.

In this paper we study Samaria gorge through recognition, recording and visualization of geomorphological characteristics. Geomorphological characteristics collected through Remote Sensing techniques, are compared with those collected through stereoscopic observation of aerial photos and fieldwork. At the first phase, the aerial photos of the studied area were scanned and through selected digital image processing algorithms, the geomorphological characteristics were stressed and recorded. At the second phase a geomorphological map was created based on data derived from stereoscopic observation of the area aerial photos and fieldwork. During fieldwork a GPS was used, which was connected with the GIS in order toimmediately record and test the measured characteristic position. Finally the combination of two methods took place in order to develop a geomorphological map.

Thera, along with the islands of Therasia, Aspronisi, Palaea and Nea Kameni, form avast roundly shaped caldera, of 8x10 km. Because of the intense volcanic activity, The shape and morphology of Thera has repeatedly changed through the years. This characteristic makes Thera, from a geological point of view, a very interesting island. Paleo-environmental and volcanic evolution is quite impressive, moreover if it is expressed through modern technology, such as GIS and modern visualization tools. As far as archaeological findings are concerned, Thera is already famous for the existence of the Minoan civilization. Volcanic activity is highly linked to both thepreservation of the archaeological findings and the destruction of the Minoan civilization over Thera Island. In this study with the use of Geographical Information Systems we propose a wide cultural park, combining all physical, geological, geomorphological and cultural characteristics, and through that the connection between volcanic activity and Minoan civilization evolution.

Cephalonia belongs to Ionian islands and consists of two alpine zones, the pro-apoulia and the Ionian one, and pleiocene and quaternary deposits. In this paper we are developing a land use / land cover map of Cephalonia island and an urban map of Argostoli town, the capital of Cephalonia, using GIS techniques and photointerpretation.

We observed EX Draconis in BV I colours for 40 nights, covering 3 outburst events, with the aim to study the disc evolution. Here, we present a preliminary eclipse-mapping study of some of the B band light curves obtained during the outburst in August 2000.

Bergeles, Nikos;  Haziharistos, Dimitris and Kamperidou, Rena (Irene).  The Meaning of the Term ‘Team’ (Omada) in the Epic Cycle. Proceedings of the 7th Annual Congress of the European College of Sport Science. Editors Maria Koskolou, Nickos Geladas, Vassilis Klissouras, Volume 2, Athens, 24-28 July, 2002, (0736/ p. 658).

After the unexpected superoutburst of WZ Sge on July 23, 2001, the light curve was dominated by the orbital variability with a switch to dominating superhumps after August 5. The time series analysis of our data has shown, that the superhumps have started at the early stage of the superoutburst.

We consider the problem of predicting a risk index of an event on the base of several predictors. The specificity of the problem lies in the fact, that there are no training data; instead we have a set of logical rules describing in a fuzzy way several classes of the risk (’very low’, ’low’, ’medium’, ’high’ and ’very high’ risk). We present several problems and doubts we had met when trying to construct a predictor. After considering several alternatives we stated that a simple neural network architecture (with one perceptron) calculating logistic regression has given the best agreement with expert opinion. Thus,based on the rules, we are able to mimic the expert opinion by a neural network model.

We analyse the fine structure of the type IV radio burst, during the main phase of the 14th July 2000 major event recorded by the radiospectrograph ARTEMIS-IV, in the 110-650 MHz (10 Hz sampling rate) and the 270-450 MHz (100 Hz rate) range. In this report we focus on variations in frequency drift rate and repetition rate of fibers bursts. A pronounced asymmetry between the number of bursts with positive and negative frequency drift is noted at certain time periods. These variations follow closely the evolution of the magnetic structure associated with the major solar event and the onset of the corresponding CME.

Andros is the 2nd biggest island in Cyclades. Its morphology is intense and derives from the lithological and tectonical characteristics of the island. In this paper we studied Andro’s island environmental characteristics using Remote Sensing and GIS techniques. A GIS database was developed including all the corresponding geographical, geological, geomorphological and environmental characteristics. Moreover, an environmental map was developed at a 1:50.000 scale that elaborates all the above data. Remote Sensing techniques were also used in combination to the traditional cartographical methods, in order to locate with maximum accuracy all these data and input them in the GIS.

In this paper we study the coastal zone in the region of Acheloos’ river mouth and delta. In recent years, this region has been subjected to a series of environmental changes, primarily due to intense human activity concerning large hydroelectricdams. These dams created between 1960 and 1986 are responsible for important changes of the river’s flow. The purpose of this study is to record the changes that have occurred between those years and present time; to define and analyze their possible consequences on the coastal geomorphology of the region. For this reason we used topographical and geological maps (scale 1:50.000), aerial photos (scale 1:33.000) and finally satellite photos. A geographical database has been created in a GIS with environmental, geological, geomorphological and anthropogenic features of the studied area. All digital data were analyzed spatially and quantitative in order to describe the change of delta shape, size and finally the occupied land use. Finally different thematic maps were created showing the geomorphological and environmental changes during those years.

The dwarf nova EX Draconis shows deep and wide eclipses, in addition to its frequent outburst activity (every 2-3 weeks), which makes it the ideal target for monitoring a complete outburst cycle. We observed EX Draconis in BVI colours with the 1.2m telescope at Kryonerion Korinthias (Greece) between 1 July-20 August 2000 covering 3 outburst events (1-5 July, 20-30 July and 6-12 August). Here, we present a preliminary eclipse mapping study of the light curves obtained in August 2000.

Samos island has recently (July 2000) experienced severe fire events that changedmost of its landcover map. Apart from this catastrophy, Samos island also encounters intense rainfalls, soil erosion and flood events. Unfortunatelly, erosion proccess are highly accelerated when natural protective mechanisms, like landcover, are absent. At Samos case, we produced an erosion risk map, using as principal attributes lithology, drainage system analysis, topography and recent landcover data. All these data, were input into the GIS and processed through fuzzy logic rules, in order to derive an erosion risk map. Such maps can be proved very useful tools, when classifying zones of high erosion risk and when taking appropriate measures in advance. Erosion risk maps can be used from both local authority and research teams that need, among others, to evaluate erosion factor or plan effective policies.

This study is dealing with two different transformation rules for creating erosionrisk thematic maps. The first rule, based on Boolean logic, is a well known theoryused for composing maps and demanding crisp sets as input data. The second one is the fuzzy logic theory, appropriate for handling fuzzy sets. In this context we present a case study from the Greek territory of Korinth. It concerns the hydrological basin where recently a catastrophic flood event has occurred. As input data we have used field measurements, aerial photos, satellite images, topographic and geological maps. These data sets were georeferrenced, digitised and introduced to a G.I.S. – web platform. The G.I.S. – web technology permits easy data and map updates. Oursoftware tools were the MapInfo G.I.S., the MapXtreme web interface and theMatLab. The aim of this paper is to emphasise on the utility of erosion risk maps forenvironmental protection and agricultural uses.

This paper presents a GIS-based geomorphological map of Milos island. In orderto create this kind of maps, one must employ a wide variety of digital processingtechniques, in order to obtain high accuracy and analysis speed. Both aerial photosand satellite images had to be geometrically and radiometrically corrected, in order to eliminate distortions. Using digital image processing techniques, different information layers were developed and imported to the MapInfo GIS. GIS software was used for the comparative spatial and quantitative analysis of all the information layers. The GIS handled all geomorphological data as separate objects. Thus, everyobject’s attributes and every distance between objects, is easily measurable. Moreover, data modifications and updates are also very quick and easy. Milos is a volcanic Aegean-sea island. Over the last decades, significant geomorphological changes have taken place, because of rapid increment of tourism. The rapid, and of a large scale, geomorphological changes that have already taken place and will continue in the future, were the reason why Milos island was selected among others to be studied from a geomorphological point of view. This paper’s aim is to record geomorphological features of Milos island in order to be compared with data that will be gathered in some years at the second stage of this study, in order to present geomorphological changes due to human activity impacts.

The modelling of plasma outflows from central gravitating objects such as AGN is briefly discussed via analytic examples in the context of ideal MHD. The exact solutions are produced via a nonlinear separation of the variables in the full set of the MHD equations. Attention is given to the questions of initial acceleration and collimation of the outflow. A quantitative criterion is provided for the transition of the morphologies from highly collimated jets to non collimated winds.

In 1999 the University of Athens installed a 0.4-m Cassegrain telescope (CCT-16, by DFM Engineering) on the roof of the Department of Astrophysics, Astronomy and Mechanics, equipped with a ST-8 CCD camera and Bessel UBVRI filters. Although the telescope was built for educational purposes, we found it can be a perfect research instrument, as we can obtain fine quality light curves of bright variable stars, even from a place close to the city center. Light curves of the δ Scuti star V1162 Ori and of the sdB star PG 1336-018 are presented, showing the ability of a 40-cm telescope to detect negligible luminosity fluctuations of relatively bright variable stars. To date, we succeed in making photometry of stars down to 15th magnitude with satisfactory results. We expect to achieve even better results in the future, as our methods still improve, and as the large number of relatively bright stars gives us the chance to study various fields of CCD photometry of variables.

The cataclysmic variable, WZ Sge, and one of prototype of of the SU Uma-type dwarf nova sub-class, went into outburst on July 23 of this year. This is its first outburst since 23 years. The brightness and rarety of the event has perhaps made it the most observed object of the year. From July 29 on, we have started a photometric monitoring of this system, mainly with B-band time series with the 1.2m telescope at Kryoneri Korinthias (Greece). Here, we will present the first preliminary light curves obtained, covering the first two and a half weeks of the outburst, from July 29 to August 9, when the star was in steady decline up to when it started to show superhumps. Our on-going monitoring will continue until December 2001.

Selecting a suitable area for a sanitary landfill is a very complicated task involvinga series of parameters. For the needs of this paper, we categorized all the parameters into five major groups: a) Geological – Geomorphological – Hydrological - Hydrogeological, b) Land planning, c) Environmental d) Operational and e) Financial. Each group may contain many sub-groups and so on. In this study we attempt to indicate the most suitable areas for the establishment ofa sanitary landfill at Naxos island, using Geographical Information Systems. Themethod of ‘multiple selection criteria’, helps to objectively specify suitable areas,based on given weight factors for each parameter.Geographical Information Systems enabled the processing of all necessaryparameters and weight factors in order to develop different theoretical models forNaxos island. All resulting areas, were automatically marked by the GIS, and the bestpossible solution was isolated. Moreover, we developed different thematic maps,graphically representing the elimination criteria and the resulting positions.

Coastal zone of the Ithaki Island consists mainly of calcareous rocks (>80%) of the Ionian geotectonic zone and secondarily of Neogene sequences, flysch and Quaternary deposits. Due to the presence of carstic limestones, vegetation is poor with the ‘makia’ type of vegetation to cover almost the half of the coastal land. In terms of coast formation, four types of coasts have been identified, according toShepard’s genetic classification; these are coasts of: tectonic origin, terrestrial deposition, subaerial erosion and marine erosion. The small coastal towns and villages occupy only the 3,1% of the coastal land being developed primarily on Quaternary deposits and in areas with small (10%) topographic slope. Beaches suitable for touristic activities are present within protected small bays and usually are associated with the presence of fluvial deposits reworked by the existed wave activity.

In this poster we present the architecture of a new music interface for blind musicians,integrated in the WEDELMUSIC1 environment which is under development at ILSP2. Our scope is tofacilitate the access of visually impaired persons to musical databases (scores, audio and MIDI files)via Internet and give them the possibility to edit and create musical scores.

It is proposed to perform accurate manoeuvring of a submarine in straight horizontal course, with independent control of elevation angle and heave velocity. Independent control is accomplished via a noninteracting control technique using a static state feedback law. The general analytic expression of the feedback controllers satisfying the I/O decoupling requirement is derived. The necessary and sufficient conditions for noninteracting control with simultaneous stability are explicitly determined in terms of the stability derivatives of the submarine.

It is proposed to perform accurate manoeuvring of a submarine in straight horizontal course, with independent control of elevation angle and heave velocity. Independent control is accomplished via a noninteracting control technique using a static state feedback law. The general analytic expression of the feedback controllers satisfying the I/O decoupling requirement is derived. The necessary and sufficient conditions for noninteracting control with simultaneous stability are explicitly determined in terms of the stability derivatives of the submarine.

We will describe recent results from the use of multi-object spectroscopy with the 2dF and Autofib systems on the AAT. Specific examples include a sample of 700 carbon stars in the LMC, for which kinematic, composition and classification data are being derived, and samples of stars in the Carina and Sculptor dwarf spheroidal galaxies. The future prospects for this type of work will be discussed.

We report on the chemical abundances of stars in the Carina dwarf spheroidal galaxy (dSph) derived from low-resolution spectra. We have determined values of [Fe/H] for 52 stars from the reduced equivalent width of the Ca II infrared triplet lines. The Carina dSph has a mean metallicity of [Fe/H] = -1.99 +/- 0.08 and an intrinsic metallicity dispersion 0.25 dex (1 sigma). By directly determining the chemical abundances of Carina stars through spectroscopy, we can overcome the age-metallicity degeneracy inherent in color-magnitude diagrams (CMDs) and determine its star-formation history with unprecedented accuracy.

C-1' acylated derivatives of 2'-deoxyuridine were obtained either by revising the existing procedures or by introducing a new methodology.

Coastal zone of the Ithaki Island consists mainly of calcareous rocks (>80%) of the Ionian geotectonic zone and secondarily of Neogene sequences, flysch and Quaternary deposits. Due to the presence of carstic limestones, vegetation is poor with the ‘makia’ type of vegetation to cover almost the half of the coastal land. In terms of coast formation, four types of coasts have been identified, according to Shepard’s genetic classification; these are coasts of: tectonic origin, terrestrial deposition, subaerial erosion and marine erosion. The small coastal towns and villages occupy only the 3,1% of the coastal land being developed primarily on Quaternary deposits and in areas with small (10%) topographic slope. Beaches suitable for touristic activities are present within protected small bays and usually are associated with the presence of fluvial deposits reworked by the existed wave activity.

Η εισήγηση στο συνέδριο δημοσιεύθηκε στα Πρακτικά και αποτέλεσε τη μοναδική από θεολογικής απόψεως ανακοίνωση για το οικολογικό πρόβλημα. Προβλήθηκε, η διαδομένη στους θεολογικούς χώρους θέση, ότι το οικολογικό πρόβλημα είναι κυρίως ηθικό και οφείλεται στη διατάραξη της σχέσης ανθρώπου-Θεού και κατόπιν ανθρώπου-περιβάλλοντος. Αν θεωρηθεί καθ’ αυτόν τον τρόπο, είναι δυνατό να βρεθούν λύσεις με τη βοήθεια της  ανάλογης παιδείας και αλλαγής νοοτροπίας, δηλαδή μιας ειλικρινούς μετάνοιας.

Spectra of 480 blue horizontal branch (BHB) stars in ω Centauri have been obtained using the multiobject fiber spectroscopic facility, Autofib, at the 3.9 m AAT. Preliminary analysis in the temperature range 7500K - 8200K indicates that a large fraction of BHB stars are at lower metallicities compared to the RR Lyrae stars and the giants. This could possibly be used to elucidate how mass loss efficiency varies with metallicity. The data can also be used together with simulated HBs to derive the variation of HB luminosity with metallicity.

This study aims to investigate the day by day relationship between mesoscale circulation and air quality over the Metropolitan Athens for a period of thirteen years spatially and seasonally. Eleven distinct mesoscale patterns are remarkable based in a formulated methodology based on surface and upper air wind measurements. The air quality conditions were attributed into seven distinct classes for five main pollutants namely, O3, NO2, SO2, CO and Black Smoke (BS). It was found that the severe and bad air quality conditions over the Metropolitan Athens area are mainly associated with weak southerly flows. The most serious pollution problem in AMA is attributed to O3 in the warm period when is favoured even by intense northerly flow. Due to the complex topography and the distribution of industrial and anthropogenetic activities in the examined area, the relationship between the air pollutant’s concentration and mesoscale air circulation presents important spatial characteristics that are further investigated.

Irregular galaxies are generally less massive and less evolved systems than spirals. They constitute a different sort of system in which to study the processes of star formation and galactic evolution. The star formation history of Irregular Galaxies may be affected by several different factors. However, detailed knowledge of the star-formation history of a significant number of objects is necessary before it becomes possible to determine which parameters are important. In the last few years, there has been significant progress on this front. For the first time, we begin to probe in some detail the star-formation history of a fair number of resolved Irregulars in the Local Group. In the present, these results are summarized.

General theorems and various analytical self-similar solutions have recently shown that magnetized and rotating astrophysical outflows may become asymptotically cylindrical, in agreement with observations of cosmical jets. A notable common feature in all such self-consistent, self-similar MHD solutions is that before final cylindrical collimation is achieved, the jet passes from a stage of oscillations in its radius, Mach number and other physical parameters. It is shown that under rather general assumptions this oscillatory behavior of collimated outflows is not restricted to the few specific models examined so far, but instead it seems to be a rather general physical property of an MHD outflow which starts noncylindrically before it reaches collimation. It is concluded thence that astrophysical jets are structurally stable to small amplitude, time-independent perturbations in their asymptotically cylindrical shape.

Oxidised porous silicon emits luminescence in two distinct bands in the visible region. The fast blue (τ ∼ ns) and slow red (τ ∼ μs at 300K) bands are studied via the separate methods of time-resolved XEOL in single-bunch mode and wavelength-selective and total XEOL in multi-bunch mode. Measurements have been conducted at the silicon K-edge (1840eV) and L2,3-edge for freshly prepared and oxidised porous silicon and related samples. Both methods give conclusive evidence that the fast, blue luminescent site is defects in silica or suboxide formed near to the Si/ SiO2 interface, whereas the slower, red band originates from smaller silicon particles of diameter 14Å or less found in porous silicon. The XEOL process is discussed and range estimates of the spatial separation between the photoionisation event and radiative recombination are made.

We consider the problem of sequential control for a finite state and action Markovian Decision Process with incomplete information regarding the transition probabilities P ∈ Papprox. Under suitable irreducibility assumptions for Papprox.. We construct adaptive policies that maximize the rate of convergence of realized rewards to that of the optimal (non adaptive) policy under complete information. These adaptive policies are specified via an easily computable index function, of states, controls and statistics, so that one takes a control with the largest index value in the current state in every period.

Οἱ σχέσεις μεταξὺ τῶν δύο χωρῶν εἶναι ἱστορικῶς, θὰ ἐλέγαμε, τεταμένες. Ἡ Τουρκία, ἔχουσα πλήρη συνείδηση τῆς χρησιμότητος τοῦ ὕδατος ὡς ρητορικοῦ ὅπλου ἀλλὰ καὶ ἰσχυροῦ διαπραγματευτικοῦ μέσου ἔχει διατυπώσει urbi et orbi τὰς ἀντιρρήσεις της πρὸς πάσης φύσεως παραχωρήσεις στὸ θέμα αὐτό. Το παρόν άρθρο αναφέρεται στις σχέσεις Τουρκίας-Συρίας-Ἰράκ και στο ὑδρογεωπολιτικὸν παίγνιον.

The fundamental mechanisms controlling the light emission from porous Si remain unresolved. In this paper we report attempts to modify the luminescence using a variety of surface processing steps, such as vacuum annealing with subsequent anneals in nitrogen and oxygen, exposure to hydrofluoric acid (HF) and rapid thermal oxidation. Luminescence, infrared absorption, and electron spin resonance (ESR) have all been used to gain more information on the link between the optical emission and the localisation of the electrons in this material system. We present evidence that the silicon dangling bond is the key component in the non-radiative recombination. This is based on measurements shown that hydrogen coverage of the surface is significant because of saturation of the dangling bonds and a subsequent reduction in the competing non-radiative paths rather than as an active component in the radiative transition. Finally, we focus our attention upon the lower energy band which appears in the luminescence spectrum of porous Si (approx.0.9eV) by examining its behavior under the surface treatments mentioned above. We found that this luminescence band originates from the surface of the porous layer and its intensity correlates well with increasing oxidation of the porous layer.