608 research outputs found
Nikolaos Politis: Study on the life of modern Greeks
No full textTitle: Μελέτη ἐπί τοῦ βίου τῶν νεοτέρων Ἑλλήνων (Study on the life of modern Greeks) Originally published: in Τόμος Α’ (vol. I), ‘Νεοελληνική Μυθολογία’ of the four-volume Μελέτη ἐπί τοῦ βίου τῶν νεοτέρων Ἑλλήνων (Athens: τύποις Σαραντάκος Οἰκονόμου, 1871). Language: Greek The excerpts used are from the original, Preface, pp. α’- γ.’ About the author Nikolaos Politis [1852, Kalamata..
The Early Byzantine Domed Basilicas of West Asia Minor, An essay in Graphic Reconstruction
No full textThis paper investigates the methodology employed in the recent survey and reconstruction of the major Early Byzantine domed churches of west Asia Minor. This involved both the documentation of construction details as well as their interpretation by reference to coeval monuments elsewhere. Focusing on this methodology, the author explores techniques of graphic recording and the theoretical framework within which parallels with other buildings can inform the work of reconstruction. The detailed examination of two case studies illustrates the way in which seemingly random scraps of testimony were interpreted to provide evidence for the missing superstructure of the churches. These case studies also serve to explore the adaptation of the methodology to sites with different characteristics and help to assess the credibility of the resulting graphic reconstructions
Author self-citation in orthodontics is associated with author origin and gender.
No full textBACKGROUND
The aims of this bibliometric study were to determine author self-citation trends in high-impact orthodontic literature and to investigate possible association between self-citation and publication characteristics.
METHODS
Six orthodontic journals with the highest impact factor as ranked by 2017 Journal Citation Reports were screened for a full publication year (2018) for original research articles, reviews, and case reports. Eligible articles were scrutinized for article and author characteristics and citation metrics. Univariable and multivariable negative binomial regression was used to examine associations between self-citation incidence and publication characteristics.
RESULTS
Medians for author self-citation rate of the most self-citing authors and self-citations were 3.03% (range 0-50) and 1 (range 0-19), respectively. In the univariable analysis, there was no association between self-citation counts and study type (P = 0.41), article topic (P = 0.61), number of authors (P = 0.62), and rank of authors (P = 0.56). Author origin (P = 0.001), gender (P = 0.001) and journal (P = 0.05) were associated with self-citation counts and in the multivariable analysis only origin and gender remained strong self-citation predictors. Asian authors and females self-cited significantly less often than all other regions and male authors.
CONCLUSIONS
Authors in orthodontics do not self-cite at a frequency that suggests potential citation manipulation. Author origin and gender were the only variables associated with citations counts. More bibliometric research is necessary to draw solid conclusions about author self-citation trends in orthodontic literature
Corporate Governance in major listed Construction Companies in Greece: Analysis, comparison, and best practices. Survey on Employees' awareness and evaluation on applied Corporate Governance practices.
No full textInformation theory methods in communication complexity
No full textThis dissertation is concerned with the application of notions and methods from the field of information theory to the field of communication complexity. It consists of two main parts. In the first part of the dissertation, we prove lower bounds on the randomized two-party communication complexity of functions that arise from read-once boolean formulae. A read-once boolean formula is a formula in propositional logic with the property that every variable appears exactly once. Such a formula can be represented by a tree, where the leaves correspond to variables, and the internal nodes are labeled by binary connectives. Under certain assumptions, this representation is unique. Thus, one can define the depth of a formula as the depth of the tree that represents it. The complexity of the evaluation of general read-once formulae has attracted interest mainly in the decision tree model. In the communication complexity model many interesting results deal with specific read-once formulae, such as disjointness and tribes. In this dissertation we use information theory methods to prove lower bounds that hold for any read-once formula. Our lower bounds are of the form n(f )/c^d(f ) , where n(f ) is the number of variables and d(f ) is the depth of the formula, and they are optimal up to the constant in the base of the denominator. In the second part of the dissertation, we explore the applicability of the information-theoretic method in the number-on-the-forehead model. The work of Bar-Yossef, Jayram, Kumar & Sivakumar [BYJKS04] revealed a beautiful connection between Hellinger distance and two-party randomized communication protocols. Inspired by their work and motivated by the open questions in the number-on-the-forehead model, we introduce the notion of Hellinger volume. We show that it lower bounds the information cost of multi-party protocols. We provide a small toolbox that allows one to manipulate several Hellinger volume terms and also to lower bound a Hellinger volume when the distributions involved satisfy certain conditions. In doing so, we prove a new upper bound on the difference between the arithmetic mean and the geometric mean in terms of relative entropy. Finally, we show how to apply the new tools to obtain a lower bound on the informational complexity of the ANDk function.Ph. D.Includes bibliographical referencesby Nikolaos Leonardo
Nikolaos Mesarites, Description of the Church of the Holy Apostles at Constantinople. New critical perspectives.
No full textThis study offers a reappraisal of Nikolaos Mesarites’ Description of the church of the Holy Apostles at Constantinople, by providing new insights into its genre and the context of its composition. By concentrating on the text’s encomiastic features, the first part of the study retraces its carefully carved rhetorical construction. The second part analyses the so far neglected concluding section of the Description, in which the author, by hinting at the current historical juncture – the very years preceding the fourth Crusade – would seem to disclose a specific purpose for its composition. Finally, an hypothesis for dating the Description is also suggested, with the intention of defining it further in a forthcoming dedicated article.
Correction: Operative management of acute abdomen after bariatric surgery in the emergency setting: the OBA guidelines (World Journal of Emergency Surgery, (2022), 17, 1, (51), 10.1186/s13017-022-00452-w)
No full textFollowing publication of the original article [1], the co-author “Nikolaos Pararas” has misspelled wrongly as “Nikolaos Parasas”. The original article has been corrected. © The Author(s) 2022
Correction: Operative management of acute abdomen after bariatric surgery in the emergency setting: the OBA guidelines (World Journal of Emergency Surgery, (2022), 17, 1, (51), 10.1186/s13017-022-00452-w)
No full textFollowing publication of the original article [1], the co-author “Nikolaos Pararas” has misspelled wrongly as “Nikolaos Parasas”. The original article has been corrected
Two dimensional materials synthesis for electronic and optoelectronic applications
No full textAtomically thin materials offer unique optical, electronic and physical properties due to quantum connement effects. Graphene has been the material that has primed the extensive research interest in the field. The lack of an energy bandgap in graphene helped to expand the research of 2D materials beyond graphene, in search for application tailored properties. The strongest overall candidate for electronic applications has since been Transition Metal Dichalcogenides (TMDCs). The metal-chalcogen bonds are strong covalent bonds that form stacked layers together by weak Van der Waals forces and can hence be easily separated to form individual layers. The significance of this ability lies in the fact that although TMDCs have an indirect bandgap in their bulk form, they transition to a direct bandgap in single layer form. This property is important for optoelectronic applications as it results in an enhanced photoluminescence quantum yield. A monolayer of such a material offers very high effective mobility that would otherwise require three times thicker single crystal silicon layer to reach. Transistors made of TMDCs have also been shown to reach the thermal transport limit achieving a subthreshold swing of as low as 60 mV/dec and on/off ratios of 108. Those attributes make TMDCs an ideal candidate for next generation electronic and optoelectronic applications potentially replacing current material technologies. Due to the weak Van der Waals forces between layers one of the first methods explored to obtain single layers of graphene and TMDCs has been exfoliation and transfer techniques involving tape, chemical or mechanical methods. Those techniques viii have been providing very high quality single crystal layers with excellent electronic and optoelectronic properties. A direct drawback of these methods is the lack of scalability. For this reason, there has been a collective research effort in the community towards the development of direct growth methods for TMDCs that are scalable and can be used in traditional top-down fabrication processes. Scalable techniques have recently included RF sputtering, CVD and ALD techniques that use solid, metal halide or organic precursors. Most of those studies rely on the transfer of the TMDC after it has been grown in order to form electronic devices such as field effect transistors. The main reason for this is that during the growth process the dielectric integrity of the underlying SiO2, on which the films are commonly grown, is compromised. This work aims to tackle the scalability of 2D materials by devising methods directly applicable to wafer scale production. In particular, for TMDCs a combination of Atomic Layer deposition and Thermal reaction is used to form a few layer MoS2 on a SiO2 substrate without the need for transfer to perform as an FET device. Using ALD, a thin layer of MoO3 is first formed on the SiO2 and then annealed in a CVD reactor in presence of H2S. As the wafers are already coated with MoO3 during the high temperature anneal in H2S the SiO2 quality is preserved removing the need to transfer to a fresh substrate and therefore enabling the practical upscale of the technology. This thesis discusses the methods developed by the author for growing 2D films of graphene, MoS2 and HfS2. The results from the characterization of the films at a variety of growing conditions provide a comprehensive guide to optimizing the film growth for optoelectronic and electronic applications. Moreover new fabrication protocols have been designed in order to accommodate the fragile nature of 2D materials while making high performance devices. This work provides an array of devices as performance demonstrators such as FET, fiber modulator, mechanochromic metamaterial and graphene photodetector. The most significant achievement of this work is the design of the full fabrication protocol for high performance FET devices and the resulting performance of these devices. It was demonstrated that a subthreshold slope of under 180 mV/dec and an on/off ratio of more than 104 can be achieved with directly grown transistors in a readily scalable process
- …
