325 research outputs found
Velocity profiles of sea currents
No full textSome monitoring surveys were carried out in spring seasons, during March 2003, along the Southern Adriatic coast. A vessel mounted acoustic Doppler current profiler was used to measure the vertical distributions of current velocities in some selected stationing points. At the same time and locations also a CTD recorder was used to measure water temperature and salinity. The aim of the paper is to investigate these field measurements of sea currents and to model the measured velocity vertical profiles by means of some classical empirical laws, thus testing their ability to reproduce the velocity field. The analyzed data refer to a complex domain, characterized by an irregular bathymetry and a roughness due to non uniformseabed vegetation. Consequently the validity of the theoretical velocity laws along with their classic parameter values has not necessarily to be expected. Therefore, a modified form of the velocity-defect law is here proposed
Random iteration on hyperbolic Riemann surfaces
No full textLet {f_ν} ⊂ Hol(X,X) be a sequence of holomorphic self-maps of a hyperbolic Riemann surface X. In this paper we shall study the asymptotic behavior of the sequences obtained by iteratively left-composing or right-composing the maps {f_ν}; the sequences of self-maps of X so obtained are called left (respectively, right) iterated function systems. We shall obtain the analogue for left iterated function systems of the theorems proved by Bear-don, Carne, Minda and Ng for right iterated function systems with value in a Bloch domain; and we shall extend to the setting of general hyperbolic Riemann surfaces results obtained by Short and the second author in the unit disk D for iterated function systems generated by maps close enough to a given self-map
Σύνθεση και Χαρακτηρισμός Βιολογικά Ενεργών Οξειδοαναγωγικών μορίων Βαναδίου με Πολυφαινικούς υποκαταστάτες
No full textIn this work, we introduce new transition metal complexes with phenolic ligands which are models for the study of metabolic pathways in food matrixes and biological systems. In addition, there was a study upon the mechanism of radicals that created with the interaction of the phenols with metal ions. That possibility was in great interest because of the use of those kinds of systems as anticancer drugs. Finally, we developed an analytical method in order to be able to evaluate these phenol molecules in biological systems. In particular, hydroquinones and tocopherols were fluoro-labelled and vanadium labelled to be easily observed and evaluated with 19F and 51V NMR, EPR and UV-Vis spectroscopy. The quantification of the molecules using the 19F NMR took place in olive oil environment which is very like the cell membrane environment. The antioxidant action of the metal-organic molecules with the metal ions, in addition with the radical induced mechanisms were evaluated with spectroscopy, crystallography and electrochemically. Antioxidants are components of foods and there are biomolecules that are necessary for the ordinary function of human body. They used as conservatives in food matrixes against oxidation. Hydroquinones are model molecules for antioxidants and tocopherols containing a saturated phytyl chain and a different placement of methyl groups on the chromanol ring. Tocotrienol isoforms have an unsaturated side chain. Vitamin E is a generic term that represents a family of compounds composed of various tocopherol and tocotrienol isoforms. Tocopherols display potent anti-angiogenic and antiproliferative activities. Redox silent tocopherol analogues also display potent anticancer activity. Polyphenolic compounds in biological systems could easily interact with metal ions producing free radical species causing several diseases in human body. The true is that controlled production of free radicals could induce apoptosis of cancer cells. Especially vitamin E and its analogues are very active in mitochondria of cells and they are potential drugs acting against cancer cells. It is also well known that tocopherol analogues are targeting only cancer cells because they are very high redox active. Even though the above reactions are very useful there are are some drawbacks in their study. There is a lack of well-known metal -organic molecules with notable mechanism of action. In this work, we are introducing new analytical methods for the determination of those models in order to be able to monitor their metabolic pathways in biological systems and we have studied the redox mechanisms behind this action and their interaction with vanadium metal ions for possible use as anticancer drugs.Keramidas Anastasios
Drouza Chryssoula
Theocharis Charis
Kapnissi-Christodoulou ConstantinaComplete
A comparative case study of coordination mechanisms in Design and Build BIM-based projects in the Netherlands
No full textBIM implementation can affect the project coordination mechanisms in unexpected ways, even in widely-applied project procurement structures. Apart from the chosen procurement approach, the BIM technology and the distribution of roles in the project team influence and shape the project coordination. This paper aims to explore the emerging coordination structures and processes from BIM implementation in design-build procurement. An exploratory comparative case study has been undertaken. The findings included two main coordination mechanisms: a centralized and decentralized structure and a hierarchical ver-sus participative decision-making processes. These two patterns subsequently open a debate about the rela-tions between BIM implementation and business models in AEC and particularly the emergence of specialized all-around BIM firms versus BIM-knowledgeable engineering firms.Accepted Author ManuscriptDesign & Construction Managemen
Bioengineering in front of a river dike:Wave attenuation by vegetation
No full textBioengineering is a novel way to reduce the application or dimensions of hard constructions. In the Dutch Noordwaard polder a vegetation field is proposed in front of a planned dike to damp waves such that the desired dike height can be reduced. To investigate the impact of vegetation on waves, the description for wave attenuation as derived by Mendez and Losada (2004) was implemented in the wave model SWAN. The SWAN-VEG model was tested by performing a sensitivity analysis and by calibration and validation on experimental flume data. The model showed expected behavior and calibrated values for the drag coefficient gave reasonable correlations between predicted and measured wave attenuation, except for a plant with flexible floating leaves. Application of the model to the Noordwaard polder showed that a field of willows is able to reduce wave heights by 70% under extreme conditions. This allows a lower dike that fits better into the landscape while maintaining the required safety standard
Facilitating the BIM coordinator and empowering the suppliers with automated data compliance checking
No full textIn projects with Building Information Modelling (BIM), the collaboration among the various actors is a very intricate and intensive process. The various suppliers and engineers provide their input in Industry Foundation Classes (IFC), which in turn is used for design coordination. However, the IFCs have to undergo an intermediate checking process to ensure compliance with various client-set and technical requirements. The paper focuses on the potential of (semi-)automatic IFC compliance checks and discusses a relevant recent initiative in the Netherlands, according to which several IFC compliance criteria were agreed among 14 contractors. This study aims to unravel the changes induced by this development not only as to the IFC compliance checks, but also as to potentially balancing the roles between the BIM coordinator and the suppliers.Accepted Author ManuscriptDesign & Construction Managemen
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Maritime Safety Law and Policies of the European Union and the United States of America: Antagonism or Synergy? /
No full textThe International Maritime Organization (IMO), as the United Nations specialized agency responsible for the regulation of shipping engaged in international trade from the points of view of maritime safety and the prevention and control of pol- tion by ships, recognizes that these goals can only be effectively achieved if each and every link in the corresponding chain of responsibility meets fully its obli- tions. Flag, port and coastal States, as well as the shipping industry itself, all have roles to play in collectively improving safety and protecting the environment, both marine and atmospheric, through the development, adoption, and uniform imp- mentation and enforcement of, global standards. In this book, Dr. Christodoulou-Varotsi sets out to explore the extent to which the actions of the European Union and the United States, as the main originators of high standards in these fields, constitute a paradigm to the rest of the inter- tional maritime community. In this regard, while underscoring the need for a - listic, multilateral approach to maritime regulation - as epitomized by the work of IMO - the author explores how standards could be enhanced through the use of unilateral action
Convergence and approximation in potential games
No full textAbstractWe study the speed of convergence to approximately optimal states in two classes of potential games. We provide bounds in terms of the number of rounds, where a round consists of a sequence of movements, with each player appearing at least once in each round. We model the sequential interaction between players by a best-response walk in the state graph, where every transition in the walk corresponds to a best response of a player. Our goal is to bound the social value of the states at the end of such walks. In this paper, we focus on two classes of potential games: selfish routing games, and cut games (or party affiliation games (Fabrikant et al. 2004 [12])).Other than bounding the price of anarchy of selfish routing games (Roughgarden and Tardos, 2002 [25], Awerbuch et al. 2005 [2], Christodoulou and Koutsoupias, 2005 [9]), there are many interesting problems about game dynamics in these games. It is known that exponentially long best-response walks may exist to pure Nash equilibria (Fabrikant et al. 2004 [12]), and random best-response walks converge to solutions with good approximation guarantees after polynomially many best responses (Goemans et al. 2005 [17]). In this paper, we study the speed of convergence on deterministic best-response walks in these games and prove that starting from an arbitrary configuration, after one round of best responses of players, the resulting configuration is a Θ(n)-approximate solution. Furthermore, we show that starting from an empty configuration, the solution after any round of best responses is a constant-factor approximation. We also provide a lower bound for the multi-round case, where we show that for any constant number of rounds t, the approximation guarantee cannot be better than nϵ(t), for some ϵ(t)>0.We also study cut games, that provide an illustrative example of potential games. The convergence of potential games to locally optimum solutions has been studied in the context of local search algorithms (Johnson et al. 1988 [19], Schaffer and Yannakakis, 1991 [28]). In these games, we consider two social functions: the cut (defined as the weight of the edges in the cut), and the total happiness (defined as the weight of the edges in the cut, minus the weight of the remaining edges). For the cut social function, we prove that the expected social value after one round of a random best-response walk is at least a constant factor approximation to the optimal social value. We also exhibit exponentially long best-response walks with poor social value. For the unweighted version of this cut game, we prove Ω(n) and O(n) lower and upper bounds on the number of rounds of best responses to converge to a constant-factor cut. In addition, we suggest a way to modify the game to enforce a fast convergence in any fair best-response walk. For the total happiness social function, we show that for unweighted graphs of sufficiently large girth, starting from a random configuration, greedy behavior of players in a random order converges to an approximate solution after one round
DEAPHYSEAL FEMORAL FRACTURES AND RIGID FIXATION
No full textTHE SUBJECT OF THIS THESIS IS THE STUDY OF 106 PATIENTS OUT OF 176 SUFFERING FROM DIAPHYSAL FEMORAL FRACTURES, TREATED BY PLATING. THE AVERAGE FOLLOW UP FORTHE 106 PATIENTS WAS 4,4 YEARS. 45 PATIENTS SUFFERED MULTIPLE INJURIES AND 65FRACTURES WERE COMMINUTED. ALTHOUGH THE GOAL OF TREATMENT WAS RIGID INTERNALFIXATION THE PLATE WAS APPLIED IN SOME CASES AS A BRIDGE OF THE COMMINUTED AREA, NECESSARY TO MAINTAIN LENGTH AS WELL AS TO ENSURE RECONSTITUTION AND REVASCULARIZATION OF FRAGMENTS. AT THE REST OF THE CASES THE PLATE WAS APPLIED EITHER AS A NEUTRALIZATION ONE OR AS TENTION BAND. IN 81 PATIENTS (76,3%) THE RESULTS WERE SATISFACTORY AND IN 5 PATIENTS (4,7%), WHO SUFFERED MULTIPLE INJURIES IN THE SAME LIMB, THE RESULTS WERE POOR. IN 20 PATIENTS (18,8%) ONE OF THEMAJOR COMPLICATIONS WAS PRESENT. THE ABOVE CASES WERE INCLUDED NEITHER IN THE GROUP OF SATISFACTORY RESULTS NOR IN THE GROUP OF POOR ONES. THEY WERE STUDIED SEPARETLY BECAUSE OF THE NUMBER AND VARIETY OF FACTORS INVOLVED. THE MORESERIOUS COMPLICATIONS WERE: A) INFECTION WAS DEVELOPED IN 7 PATIENTS (6,6%) AND IN ALL THESE CASES THE OPERATING TIME WAS OVER 90 MIN. (AVERAGE 122 MIN.). THE EARLY POST - OPERATIVE ANTIBIOSES SEEMED OF NO VALUE. B) PLATE BREAKAGEOCCURED IN 11 PATIENTS (10,3%). PATRIAL CORTICAL DEFECT AFTER THE OSTEOSYNTHESIS OF COMMINUTED FRACTURES WAS IN RETROSPECT THE MOST COMMON RADIOLOGICAL FINDING BEFORE FAILURE. PRIMARY OR EARLY SECONDARY GRAFTING (ABSTRACT TRUNCATED)ΤΟ ΑΝΤΙΚΕΙΜΕΝΟ ΤΗΣ ΜΕΛΕΤΗΣ ΑΥΤΗΣ ΕΙΝΑΙ 106 ΠΕΡΙΠΤΩΣΕΙΣ ΑΣΘΕΝΩΝ ΑΠΟ 176 ΜΕ ΚΑΤΑΓΜΑ ΤΗΣ ΔΙΑΦΥΣΕΩΣ ΤΟΥ ΜΗΡΙΑΙΟΥ ΟΣΤΟΥ, ΤΟ ΟΠΟΙΟ ΟΣΤΕΟΣΥΝΤΕΘΗΚΕ ΜΕ ΕΥΘΕΙΑ ΠΛΑΚΑ ΚΑΙ ΒΙΔΕΣ. ΟΙ 106 ΑΣΘΕΝΕΙΣ ΠΑΡΑΚΟΛΟΥΘΗΘΗΚΑΝ ΓΙΑ ΔΙΑΣΤΗΜΑ ΚΑΤΑ ΜΕΣΟ ΟΡΟ 4,4 ΧΡΟΝΙΑ. 45 ΑΣΘΕΝΕΙΣ ΕΙΧΑΝ ΠΟΛΛΑΠΛΟΥΣ ΤΡΑΥΜΑΤΙΣΜΟΥΣ ΚΑΙ 65 ΑΠΟ ΤΑ ΜΗΡΙΑΙΑ ΚΑΤΑΓΜΑΤΑ ΗΤΑΝ ΣΥΝΤΡΙΠΤΙΚΑ. Ο ΣΚΟΠΟΣ ΤΗΣ ΘΕΡΑΠΕΙΑΣ ΗΤΑΝ Η ΣΤΑΘΕΡΗ ΣΥΜΠΙΕΣΤΙΚΗ ΟΣΤΕΟΣΥΝΘΕΣΗ ΜΕ ΤΗΝ ΕΦΑΡΜΟΓΗ ΤΗΣ ΠΛΑΚΑΣ Η ΣΑΝ ΕΞΟΥΔΕΤΕΡΩΤΙΚΗΣ ΦΟΡΤΙΩΝ (NEUTRALIZATION PLATE) Η ΣΑΝ ΤΑΙΝΙΑΣ ΕΛΚΥΣΜΟΥ (TENSION BAND). ΟΜΩΣ Η ΠΛΑΚΑ ΧΡΗΣΙΜΟΠΟΙΗΘΗΚΕ ΑΡΚΕΤΕΣ ΦΟΡΕΣ ΣΑΝ ΓΕΦΥΡΟΠΟΙΗΤΙΚΗ (BRIDGING PLATE), ΓΙΑ ΝΑ ΔΙΑΤΗΡΗΣΗ ΤΟ ΜΗΚΟΣ ΤΟΥ ΜΗΡΙΑΙΟΥ ΜΕΧΡΙ ΤΗΝ ΠΩΡΩΣΗ. ΣΕ 81 ΑΣΘΕΝΕΙΣ (76,3%) ΤΟ ΤΕΛΙΚΟ ΑΠΟΤΕΛΕΣΜΑ ΗΤΑΝ ΙΚΑΝΟΠΟΙΗΤΙΚΟ, ΕΝΩ ΣΕ 5 ΑΣΘΕΝΕΙΣ, ΠΟΥ ΕΙΧΑΝ ΚΙ ΑΛΛΕΣ ΚΑΚΩΣΕΙΣ ΣΤΟ ΙΔΙΟ ΜΕΛΟΣ ΠΟΥ ΕΠΗΡΕΑΖΑΝ ΤΗ ΛΕΙΤΟΥΡΓΙΚΟΤΗΤΑ ΤΟΥ, ΤΟ ΤΕΛΙΚΟ ΑΠΟΤΕΛΕΣΜΑ ΗΤΑΝ ΦΤΩΧΟ (4,7%). 20 ΑΣΘΕΝΕΙΣ ΕΜΦΑΝΙΣΑΝ ΜΙΑ ΕΠΙΠΛΟΚΗ (18,8%). ΟΙ 20 ΑΥΤΕΣ ΠΕΡΙΠΤΩΣΕΙΣ ΔΕΝ ΣΥΜΠΕΡΙΛΗΦΘΗΚΑΝ ΣΤΗΝ ΟΜΑΔΑ ΤΩΝ ΙΚΑΝΟΠΟΙΗΤΙΚΩΝ ΑΠΟΤΕΛΕΣΜΑΤΩΝ ΑΛΛ' ΟΥΤΕ ΚΑΙ ΣΤΗΝ ΟΜΑΔΑ ΤΩΝ ΦΤΩΧΩΝ. ΜΕΛΕΤΗΘΗΚΑΝ ΟΜΩΣ ΞΕΧΩΡΙΣΤΑ, ΕΠΕΙΔΗ ΗΤΑΝ ΠΟΛΛΟΙ ΟΙ ΠΑΡΑΓΟΝΤΕΣ ΠΟΥ ΕΠΗΡΕΑΖΑΝ ΤΗ ΛΕΙΤΟΥΡΓΙΚΟΤΗΤΑ ΤΟΥ ΜΕΛΟΥΣ ΤΩΝ ΑΣΘΕΝΩΝ ΑΥΤΩΝ. ΟΙ ΚΥΡΙΩΤΕΡΕΣ ΕΠΙΠΛΟΚΕΣ ΗΤΑΝ: Α) Η ΦΛΕΓΜΟΝΗ, ΠΟΥ ΕΚΔΗΛΩΘΗΚΕ ΣΕ 7 ΑΣΘΕΝΕΙΣ (6,6%). Σ' ΟΛΕΣ ΑΥΤΕΣ ΤΙΣ ΠΕΡΙΠΤΩΣΕΙΣ Ο ΧΕΙΡΟΥΡΓΙΚΟΣ ΧΡΟΝΟΣ ΗΤΑΝ ΜΕΓΑΛΥΤΕΡΟΣ ΑΠΟ 90 ΛΕΠΤΑ ΤΗΣ ΩΡΑΣ (Μ.Ο. 122 ΛΕΠΤΑ). Η ΦΛΕΓΜΟΝΗ ΔΕΝ ΦΑΝΗΚΕ ΝΑ ΕΠΗΡΕΑΖΕΤΑΙ ΑΠΟ ΤΗΝ ΑΝΤΙΒΙΩΣΗ ΠΟΥ ΑΡΧΙΣΕ ΝΑ ΧΟΡΗΓΗΤΑΙ ΜΕΤΑ ΤΟ ΤΕΛΟΣ ΤΗΣ ΕΠΕΜΒΑΣΕΩΣ. (ΠΕΡΙΚΟΠΗ ΠΕΡΙΛΗΨΗΣ
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