The impact of information needs satisfaction on the creativity of visual art teachers.

The aim of this study is to investigate how the information needs satisfaction of visual art teachers affects their creativity. Visual art teachers' information seeking behaviour and specifically the association of information needs satisfaction with creativity has been an understudied area, despite competent information seeking being considered essential for high quality practices of art teachers. A questionnaire survey was developed addressing the information seeking behaviour of art teachers, informed by Wilson's model (1981), including visual art teachers' information needs, information resources, obstacles faced while seeking information and the perceived impact of information needs satisfaction on visual art teachers' creativity. The study included 298 visual art teachers in Greece. The results demonstrated that the key information needs of art teachers were mainly related to materials' properties, techniques for creating artwork, and artwork promotion methods. Online information sources were the preferred sources of art information, followed by colleagues, personal collections, and visits to galleries and museums Our study identified lack of time, lack of specialized libraries, and copyright, as the main barriers to information seeking. Information about art plays a substantial role in visual art education, while visual art teachers' information needs satisfaction positively influences their creative endeavours. There is a need to further explore the digital information needs of visual art teachers

Reduce Blockchain Nodes Storage Requirements by using Distributed Hash Table.

Σκοπός της παρούσας διπλωματικής εργασίας είναι η μελέτη και η ανάλυση της επαναστατικής τεχνολογίας blockchain και η πρόταση μίας νέας προσέγγισης στην υλοποίησή της. Συγκεκριμένα, εξετάζεται η ιδέα της οργάνωσης των ομότιμων του blockchain σε DHT με σκοπό την αποθηκεύση των δεδομένων του blockchain: Καθώς τα blockchain γερνάνε, το μέγεθός τους γίνεται ολοένα και μεγαλύτερο. Αυτή τη στιγμή, το Bitcoin blockchain υπερβαίνει τα 190GB. Επιπλέον, εφόσον εφαρμοστούν ορισμένες από τις ιδέες που αφορούν την αύξηση του ρυθμού των συναλλαγών, το μέγεθος του blockchain θα αυξάνεται ακόμα πιο γρήγορα. Το συνεχώς αυξανόμενο μέγεθος του blockchain είναι ένας παράγοντας που καθιστά το σύστημα περισσότερο συγκεντρωτικό, αφού πολύ λίγοι από τους κόμβους θα είναι σε θέση να διατηρήσουν ένα πλήρες αντίγραφο των δεδομένων. Εξάλλου, οι αρχειακοί κόμβοι με ανοιχτές θύρες έχουν ελάχιστα ή καθόλου κίνητρα για να σπαταλήσουν αποθηκευτικό χώρο και εύρος ζώνης, προκειμένου να διατηρήσουν όλα τα δεδομένα και να εξυπηρετήσουν έναν νέο κόμβο κατά την εκκίνησή του. Συνεπώς, είναι λογικό να θέλουμε να μετριάζεται το φορτίο τους (ειδικά αυτό που ονομάζουμε "κρύα δεδομένα", μερικά ιστορικά μπλοκ), μοιράζοντάς το σε ένα DHT. Η αξιολόγηση αυτής της πρότασης επιτυγχάνεται μέσω προσομοιώσεων του πρώτου και πιο δημοφιλούς δικτύου blockchain, του Bitcoin: Δημιουργούμε ένα απλοποιημένο DHT που θυμίζει το Chord. Ρυθμίζουμε το σύστημά μας και δημιουργούμε ένα σύστημα του οποίου τα χαρακτηριστικά είναι παρόμοια με το Bitcoin. Μετράμε διάφορες πτυχές του συστήματος μας όπως εξοικονόμηση χωρητικότητας των κόμβων συγκριτικά με την κλασική υλοποίηση, load balance, query latency, bandwidth usage. Παρουσιάζουμε τα αποτελέσματά μας, σχολιάζουμε, και καταλήγουμε σε συμπεράσματα.The purpose of this master thesis is the study and the analysis of the novel blockchain technology, as well as a proposal of a new approach on its implementation. In particular, it considers the idea of organizing the blockchain peers into a DHT in order to store the blockchain data: As blockchains get older, their size gets larger. Currently, Bitcoin blockchain is over than 190GB. In addition, as long as some of the ideas about the increase of the transaction rate put into practice, blockchain size will grow even faster. The ever-growing size of the blockchain it is a factor of making the system more centralized, since too few of the nodes will be able to keep a full replica of the data. After all, archival nodes with open ports, have little or no incentives to waste their storage and their bandwidth, in order to keep all the data and serve it to a bootstrapping node. Thus, it is reasonable to mitigate their load (especially that we call “cold data”, some historical blocks) by splitting it into a DHT. The evaluation of this proposal is achieved through simulations of the first and most popular blockchain network, the Bitcoin: We build a simplified DHT that reminds the Chord. We tune our system and we make a system whose characteristics is similar to Bitcoin. We measure several aspects of our system such as capacity savings per node compared to the amount of data that a full node stores today, load balance, query latency, bandwidth usage. We present our results, we make comments on them, and we draw a conclusion

Application of photogrammetry techniques for the visual assessment of vessels' cargo hold

Visual inspection is an integral part of Condition and Class surveys, with the results comprising of the surveyors’ opinion, documented by a sum of pictures indicating areas of interest. Although this way provides the most essential information, the communication of the results may be difficult, since isolated images cannot provide the context. Photogrammetry exploits pictorial data to provide 3D models, with a high level of accuracy and is not an uncommon method in the maritime environment. Use of such methods to support visual survey activities is examined in this work, providing the methodology for the data collection, which is structured in an algorithmic way, to enable realization by automated means (robots). The 3D model is provided, along with accuracy results

Application of photogrammetry techniques for the visual assessment of vessels’ cargo hold

Visual inspection is an integral part of Condition and Class surveys, with the results comprising of the surveyors’ opinion, documented by a sum of pictures indicating areas of interest. Although this way provides the most essential information, the communication of the results may be difficult, since isolated images cannot provide the context. Photogrammetry exploits pictorial data to provide 3D models, with a high level of accuracy and is not an uncommon method in the maritime environment. Use of such methods to support visual survey activities is examined in this work, providing the methodology for the data collection, which is structured in an algorithmic way, to enable realization by automated means (robots). The 3D model is provided, along with accuracy results

Ελεύθερες Ομάδες και η Τοπολογία των Πεπερασμένων Γραφημάτων

Η μελέτη των ελεύθερων ομάδων πολλές φορές παρουσιάζει δυσκολίες όταν γίνεται με αμιγώς ομαδοθεωρητικά εργαλεία. Χρησιμοποιώντας όμως τα γραφήματα και ειδικούς μορφισμούς μεταξύ τους, για να μελετήσουμε τις ελεύθερες ομάδες, μεγάλο πλήθος σημαντικών αποτελεσμάτων προκύπτει μέσω κομψών και διαισθητικών αποδείξεων. Στην παρούσα εργασία ακολουθώντας το άρθρο του Stallings [1] αποδεικνύονται μερικά πολύ σημαντικά αποτελέσματα που αφορούν ελεύθερες ομάδες. Μεταξύ άλλων παρουσιάζονται τα θεωρήματα του Howson και του M. Hall.In the study of free groups, in many cases difficulties arise if someone uses group-theoretic tools only. By using graphs and some special morphisms between them, as tools for this study, we can prove in an intuitive manner several crucial results on free groups. In this master thesis we follow Stallings’ paper [1] and we provide proofs on some of those results, such as the theorems of Howson and of M. Hall

Ο Κυνισμός ως ανθρωπολογική προϋπόθεση του αναρχισμού

Παρουσιάζεται μία συγκριτική αξιολόγηση του Κυνισμού με τον αναρχισμό του Godwin. Η βάση της σύγκρισης είναι ο ατομικισμός των δύο θεωριών. Το βασικό ερώτημα που απαντάται είναι αν η ανθρωπολογία του Κυνισμού θα μπορούσε να οικοδομήσει και να εκπληρώσει τους στόχους της αναρχικής κοινωνίας του Godwin. Η απάντηση στο ερευνητικό ερώτημα είναι θετική, διότι οι θεσμοί και οι πρακτικές στους οποίους ασκεί κριτική ο Godwin (κυβέρνηση, νόμοι, επανάσταση) δεν θα προέκυπταν σε μία κοινωνία Κυνικών, ενώ οι στόχοι των χαρακτηριστικών της αναρχικής κοινωνίας που οραματιζόταν ο Godwin (πολιτική και οικονομική απλοποίηση, αγαθοσύνη στις ανθρώπινες σχέσεις, παρουσία καθηκόντων και δικαιωμάτων, ιδιοκτησία και δικαιοσύνη μέσω του κοινωνικού ελέγχου) θα εκπληρώνονταν, χωρίς τα χαρακτηριστικά να απαντώνται στην ακριβή μορφή τους. Εξετάζοντας αυτό το ερώτημα παρουσιάζονται τα δύο αυτά φιλοσοφικά ρεύματα με έμφαση στην πολιτική και κοινωνική τους έκφανση και ανακύπτει η διάσταση ανάμεσα στην αρχαία και τη νεότερη πολιτική σκέψη στο ζήτημα των θεσμών.On this essay Cynicism and the individualistic anarchism of William Godwin are compared on the basis of their corresponding individualism. The main research question raised is whether the philosophical anthropology of Cynicism could reach the standards of Godwin’s anarchist society and achieve its goals. The answer given is positive because the institutions (government, laws, revolution) which Godwin criticizes would not appear in a Cynic society. Moreover the features of the ideal anarchist society (political and economical simplicity, benevolent human relations, the presence of duties and rights, property, punishment via public control) even though they would not be appeared in the exact way expressed by Godwin, their essence would be developed and in some cases even improved. Through this analysis the two different philosophical theories are presented and analyzed with the emphasis being given on their political and social aspects and also the difference between the ancient and the modernist political thought in respect to institution arises

Shorter courses of parenteral antibiotic therapy do not appear to influence response rates for children with acute hematogenous osteomyelitis: a systematic review

BACKGROUND: Acute hematogenous osteomyelitis (AHO) occurs primarily in children and is believed to evolve from bacteremia followed by localization of infection to the metaphysis of bones. Currently, there is no consensus on the route and duration of antimicrobial therapy to treat AHO. METHODS: We conducted a systematic review of a short versus long course of treatment for AHO due primarily to Staphylococcus aureus in children aged 3 months to 16 years. We searched Medline, Embase and the Cochrane trials registry for controlled trials. Clinical cure rate at 6 months was the primary outcome variable, and groups receiving less than 7 days of intravenous therapy were compared with groups receiving one week or longer of intravenous antimicrobials. RESULTS: 12 eligible prospective studies, one of which was randomized, were identified. The overall cure rate at 6 months for the short course of intravenous therapy was 95.2% (95% CI = 90.4, 97.7) compared to 98.8% (95% CI = 93.6, 99.8) for the longer course of therapy. There was no significant difference in the duration of oral therapy between the two groups. CONCLUSIONS: Given the potential increased morbidity and cost associated with longer courses of intravenous therapy, this finding should be confirmed through a randomized controlled equivalence trial