Η ασύμμετρη συμπεριφορά των λειτουργικών εξόδων στον τραπεζικό κλάδο, κατά την διάρκεια της οικονομικής κρίσης.

Μια θεμελιώδης υπόθεση στη βιβλιογραφία κοστολόγησης είναι ότι η σχέση μεταξύ κόστους και όγκου δραστηριότητας είναι συμμετρική ως προς το βαθμό που αυξάνεται και μειώνεται ο τελευταίος, υπονοώντας ότι οι εταιρείες μεταβάλλουν τα λειτουργικά τους έξοδα στον ίδιο βαθμό με την έκταση μιας αλλαγής στο επίπεδο δραστηριότητας, ανεξάρτητα από το την κατεύθυνση της αλλαγής. Πρόσφατες μελέτες παρ’ όλα αυτά, δείχνουν ότι τα λειτουργικά έξοδα παρουσιάζουν ασύμμετρη συμπεριφορά καθώς ο βαθμός με τον οποίο αυξάνονται όταν αυξάνονται οι πωλήσεις, είναι μεγαλύτερος από τον βαθμό με τον οποίο μειώνονται όταν μειώνονται οι πωλήσεις, ή αλλιώς “sticky cost phenomenon”. Η ασύμμετρη αυτή συμπεριφορά αποδίδεται σε επιχειρηματικές αποφάσεις και συμπεριφορές στελεχών που με τη σειρά τους χαρακτηρίζουν τις επιχειρήσεις ως αισιόδοξες ή αμυντικές ως προς την αντίδρασή τους στις μεταβολές των εσόδων, κυρίως όταν τα τελευταία μειώνονται. Η παρούσα εργασία έχει ως σκοπό την μελέτη του εν λόγω φαινομένου μέσω της ανάλυσης της αντίδρασης των 5 μεγαλύτερων ελληνικών τραπεζικών οργανισμών με σκοπό την προσαρμογή τους στα νέα οικονομικά δεδομένα, όπως διαμορφώθηκαν κατά την διάρκεια της διεθνούς οικονομικής ύφεσης 2007-2008 και της ελληνικής κρίσης που ακολούθησε. Η ανάλυση αυτή έγινε με την συλλογή των λειτουργικών εξόδων των οργανισμών για τα έτη 2004-2019 και την ανάλυση της ασύμμετρης συμπεριφοράς τους σε σχέση με τη διακύμανση των εσόδων κατά τα έτη του δείγματος.A fundamental assumption in cost accounting literature is that costs and activity volume are symmetrically related for both volume increases and decreases. This suggests that the magnitude of change in costs is directly associated with the magnitude of change in the activity volumes. However, recent studies indicate that operating costs present an asymmetric behavior as the degree of an increase in SG&A expenses with an increase in activity volume, is greater than the degree of a decrease in SG&A expenses for the same degree of decrease in activity volume, known as “sticky cost phenomenon”. This asymmetric behavior is attributed to corporate strategies and managerial behaviors resulting in classifying the companies to Prospectors and Defenders, depending on their reaction in activity volume changes, especially when the latter is decreasing. The purpose of this work is to study the “sticky cost” phenomenon by analyzing the reaction of Greece’s 5 top banks in an attempt to adapt in the new economic situation, imposed by the Financial crisis of 2007–2008 and the Greek government-debt crisis that followed afterwards. This analysis was conducted with the collection of company financial information, for the period 2004-2019 and the analysis of the potential asymmetric behavior against the changes in activity volume for the same period of the sample

Kids make their own robots: good practices from the eCraft2Learn project

This paper focuses on the small-scale pilots with learners that were carried out in Greece in the frame of the eCraft2Learn project including activities that aim at reinforcing learning by making in STEAM education. In the context of the pilots, 13-17 years-old students worked with digital fabrication and making technologies for creating robotic artefacts. In the framework of an appropriate pedagogical model that supports different steps highly interlinked, the teachers and students were invited to work together and explore the fun and the challenges of the making process using the eCraft2Learn learning ecosystem. In this line, a number of good practices were identified related to the facilitation of the learning process, the support of the ideation, the boosting of the can-do attitude, the embracement of failure and the encouragement towards sharing projects, experiences and ideas. Most of these practices are reflected in video-recorded episodes accessible through this paper. I bambini creano i propri robot: buone pratiche dal progetto eCraft2LearnIl presente lavoro documenta le prime applicazioni realizzate in Grecia, nell’ambito del progetto eCraft2Learn, dedicato a rafforzare la formazione nell’area STEAM con il learning by making. Studenti tra i 13 e i 17 anni hanno applicato tecnologie digitali e tecniche artigianali per creare artefatti robotici. Nell’ambito di un modello pedagogico appropriato, in grado di supportare diversi passi altamente interconnessi tra loro, i docenti e gli studenti sono stati invitati a lavorare insieme e ad esplorare gli aspetti di divertimento e di sfida relativi al processo creativo utilizzando l’ecosistema di apprendimento eCraft2Learn. Nel progetto sono state identificate una serie di buone pratiche relative alla facilitazione del processo di apprendimento, al supporto all’ideazione, al rinforzo di un atteggiamento positivo, all’accettazione del fallimento e all’incentivazione della condivisione di progetti, esperienze, idee. La maggior parte di queste pratiche sono state video registrate e sono rese accessibili attraverso il presente articolo

Production of white wine by Saccharomyces cerevisiae immobilized on grape pomace

White wine was produced with Saccharomyces cerevisiae cells immobilized on grape pomace, by natural adsorption. The support, the main solid waste from the wine industry, consisted of the skins, seeds and stems. Immobilization was tested using different media, namely complex culture medium, raw grape must and diluted grape must. Grape pomace was revealed to be an appropriate support for yeast cell immobilization. Moreover, grape must was shown to be the most suitable medium as immobilized cells became adapted to the conditions in the subsequent alcoholic fermentation in the wine-making process. The wines produced, either with immobilized cells or with free cells, were subjected to chemical analysis by HPLC (ethanol,glycerol, sugars and organic acids) and by gas chromatography (major and minor volatile compounds); additionally, colour (CIELab) and sensory analysis were performed. The use of immobilized systems to conduct alcoholic fermentation in white wine production proved to be a more rapid and a more efficient process, especially when large amounts of SO2 were present in the must. Furthermore, the final wines obtained with immobilized cells demonstrated improved sensory properties related to the larger amounts of ethanol and volatile compounds produced. The more intense colour of these wines could be a drawback, which could be hindered by the reutilization of the biocatalyst in successive fermentations.Zlatina Genisheva gratefully acknowledges FCT (contract/grant number: SFRH/BD/48186/2009) for financial support of this work. The authors would like to thank Divisao de Vitivinicultura Direccao Regional de Agricultura e Pescas do Norte for providing the grape pomace for yeast immobilization and the must to conduct alcoholic fermentations. The authors thank also Professor Joao Linhares for help in computing the CIELab coordinates

Extending Smart Phone Based Techniques to Provide AI Flavored Interaction with DIY Robots, over Wi-Fi and LoRa interfaces

Inspired by the mobile phone market boost, several low cost credit card-sized computers have made the scene, able to support educational applications with artificial intelligence features, intended for students of various levels. This paper describes the learning experience and highlights the technologies used to improve the function of DIY robots. The paper also reports on the students’ perceptions of this experience. The students participating in this problem based learning activity, despite having a weak programming background and a confined time schedule, tried to find efficient ways to improve the DIY robotic vehicle construction and better interact with it. Scenario cases under investigation, mainly via smart phones or tablets, involved from touch button to gesture and voice recognition methods exploiting modern AI techniques. The robotic platform used generic hardware, namely arduino and raspberry pi units, and incorporated basic automatic control functionality. Several programming environments, from MIT app inventor to C and python, were used. Apart from cloud based methods to tackle the voice recognition issues, locally running software alternatives were assessed to provide better autonomy. Typically, scenarios were performed through Wi-Fi interfaces, while the whole functionality was extended by using LoRa interfaces, to improve the robot’s controlling distance. Through experimentation, students were able to apply cutting edge technologies, to construct, integrate, evaluate and improve interaction with custom robotic vehicle solutions. The whole activity involved technologies similar to the ones making the scene in the modern agriculture era that students need to be familiar with, as future professionals

Traffic generation and analysis emphasized on ATM and IP network technologies

The information volume and the application variety are constantly increasing imposing new demands on the telecommunication networks. Due to these reasons the problem of efficient network design, monitoring and control is more apparent than ever. Traffic generation and/or analysis tools, if properly applied, can assist in finding suitable solutions. The PhD thesis focuses on the development and usage methods of similar tools and is structured in ten chapters. In the first chapter the main components of the QoS delivery problem are mentioned while the emerging need for sufficient traffic generation and/or analysis tools is justified. The second chapter presents in detail the main characteristics of the environment where the proposed tools may be used. This environment consists mainly of ATM and IP topologies. The emphasis is put on the similarities between the discussed different platforms. At chapter 3 starts the detailed description of the proposed tools. More specifically in chapter 3 an advanced software architecture for ATM traffic generation is presented. This architecture exploits a stable and reliable hardware so as to provide the generation of traffic flows compliant with high level traffic model specifications. The basic advantage of the proposed generator is that it guarantees a fast and accurate traffic generation process. The software part introduces several innovations towards minimizing speed and memory constrains related to the hardware. Chapter 4 is dedicated to the presentation of the software supporting a prototype ATM traffic analyzer. The software exploits the experience acquired during the implementation of the ATM traffic generator counterpart. The software architecture of the proposed ATM analyzer exploits and controls the enhanced capabilities of the promising underlying hardware module the role of which is expanded in order to provide real time QoS metrics at relatively low computational cost. Apart from this, the software architecture directly creates models containing some cases of traffic being monitored. In chapter 5, an IP traffic generator is described. The remarkably successful use of the prototype ATM traffic generator, in conjunction with its well-balanced architecture led to the adoption of the presented generator’s logic in IP environments as well. It must be noticed that the whole effort does not ignore the idiosyncrasies of the Internet. The IP traffic generator, despite the simplicity of its first version, was proved as very useful to many testing cases where the exact reproduction of captured traffic was crucial or the hiring of real sources too expensive or complicated. Chapter 6 is dedicated to the description of traffic analyzers, especially designed for IP networks. As a first attempt, the ATM analyzer engine was further exploited, after the necessary modifications in its software architecture, while a sufficient «IP over ATM» mechanism was hired. At next stage, a native IP analyzer was designed and implemented. The later tool hires external clock units for solving the synchronization problem between source and destination nodes. The capabilities the two analyzers can be enhanced by injecting appropriate monitoring traffic into the network under evaluation. The «IP over ATM» based IP analyzer is capable of performing accurate and fast real time measurements without overloading the hosting system. One of its main advantages is the direct delivery of histograms presenting the inter-packet distance (or the packet size) distribution. The proposed native IP analyzer solves the problem performing real time reliable measurements of end-to-end delays or losses of IP packets. Chapter 7 is dedicated to another group of performance evaluation tools that work under looser real time constrains. They perform post-processing using log files captured by various traffic analysis tools. Via post-processing more testing cases can be assessed while more complex metrics can be incorporated into the analyzer’s logic. The computational load required for measurement processing is completely disconnected from the relevant load for data gathering. Chapter 8 presents an analyzer tool that is based on the logging capabilities exhibited by advanced network elements. Although the proposed tool does not differ in its high level architecture from the other traffic analysis tools being presented, data uploading mechanism is based on the SNMP MIBs supported by network elements like an IP router or an ATM switch. The specific tool is targeted towards assisting the rest of the analyzers. The main advantage of this tool is its flexibility as it can be transferred easily from one network platform to another. Chapter 9 presents several characteristic cases where the proposed tools are involved. Indeed, traffic generation and analysis tools have been exhaustively tested during a large number of experiments. The easy use of the tools and the complementarity of their features led to the appropriate solutions very fast in all cases. Furthermore, all the tools are cost-effective. The experiments being performed indicated for one more time that there are no solutions that are both integral and optimal, but only partial ones implied by the promised QoS and cost requirements. Finally, chapter 10 summarizes the thesis’s innovative points and contribution and indicates some open issues for further research

Quality of distillates from wines produced using immobilized cells

The psychrotolenant and alcohol-resistant strain of Saccharomyces cerevisiae species Visanto, that was isolated from the island of Santorini, was immobilized in two organic (γ-alumina and mineral kissiris) and two organic (pellets of gluten and delignified cellulosic material) supports. The prepared biocatalysts were used for continuous fermentations of sterilized must. The wine making process was carried out at 16°, 20° and 30°C for all supports studied. Simultaneously, batch fermentations were conducted with free cells under the same conditions. The produced wines from continuous or batch fermentations were directly distilled in a simple distillation apparatus. The effect of the immobilization support and the fermentation temperature on the formation of volatile by-products in the distillates was also studied. The distillates were analyzed in a high resolution gas chromatograph (HRGC) for the major volatile by-products, such as methanol, acetaldehyde, ethyl acetate, propanol-1, isobutyl-alcohol and amyl alcohols. Distillates produced from delignified cellulosic material were better in quality than the other from free cells and the other supports.Το ψυχρόφιλο και αλκοολοανθεκτικό στέλεχος του S. cerevisiae Visante, που απομονώθηκε στη Σαντορίνη, ακινητοποιήθηκε σε δύο ανόργανους (γ-αλουμίνα και κίσσηρη) και δύο οργανικούς φορείς (πελλέτες γλουτένης και απολιγνινοποιημένα κυτταρινούχα υλικά). Στους βιοκαταλύτες που προέκυψαν διαβιβάστηκε αποστειρωμένο γλεύκος της ποικιλίας Ροδίτης με συνεχή ροή και πραγματοποιήθηκαν ζυμώσεις σε θερμοκρασίες 16°, 20° και 30°C. Παράλληλα έγιναν παρτίδες ζυμώσεων με ελεύθερα κύτταρα στις ίδιες συνθήκες. Τα κρασιά που παράχθηκαν υποβάλλονταν αμέσως σε απόσταξη με απλή αποστακτική συσκευή. Μελετήθηκε ο σχηματισμός πτητικών παραπροϊόντων στα αποστάγματα και εξετάστηκε η επίδραση του φορέα ακινητοποίησης και της θερμοκρασίας. Τα αποστάγματα αναλύθηκαν σε αέριους χρωματογράφους και μελετήθηκαν τα πτητικά παραπροϊόντα μεθανόλη, ακεταλδεΰδη, οξικός αιθυλεστέρας, προπανόλη-1, ισοβουτυλική αλκοόλη και αμυλικές αλκοόλες. Τα πειραματικά αποτελέσματα και ο οργανοληπτικός έλεγχος έδωσαν προβάδισμα στα αποστάγματα που προέρχονται από απολιγνινοποιημένα κυτταρινούχα υλικά. Έγινε πρόταση χρησιμοποίησης ενός βελτιωμένου Μ Ε Β Τα βιοαντιδραστήρα για παραγωγή κρασιών και αποσταγμάτων σε σύζευξη με οικονομική ανάλυση. The psychrotolenant and alcohol-resistant strain of Saccharomyces cerevisiae species Visanto, that was isolated from the island of Santorini, was immobilized in two organic (γ-alumina and mineral kissiris) and two organic (pellets of gluten and delignified cellulosic material) supports. The prepared biocatalysts were used for continuous fermentations of sterilized must. The wine making process was carried out at 16°, 20° and 30°C for all supports studied. Simultaneously, batch fermentations were conducted with free cells under the same conditions. The produced wines from continuous or batch fermentations were directly distilled in a simple distillation apparatus. The effect of the immobilization support and the fermentation temperature on the formation of volatile by-products in the distillates was also studied. The distillates were analyzed in a high resolution gas chromatograph (HRGC) for the major volatile by-products, such as methanol, acetaldehyde, ethyl acetate, propanol-1, isobutyl-alcohol and amyl alcohols. Distillates produced from delignified cellulosic material were better in quality than the other from free cells and the other supports

Flexible techniques for fast developing and remotely controlling DIY robots, with AI flavor

During the last years we are witnessing a very successful osmosis between innovative and cost-effective credit card - sized computers and education. These computers, equipped with low cost sensors or actuators, can be the “heart” of various DIY robotic artefacts. This environment allows for a mixture of thinking and making activities that can be very meaningful in terms of pedagogy and science. Indeed, similar practices, usually referred as STEM or STEAM activities, are applied in many educational institutions, from primary schools up to universities, with most of the effort to focus on secondary school students. The overall process, although promising at the beginning, is not always straightforward to keep up with. More specifically, as students get more experience, they develop a hunger for more complicated scenarios that usually demand features like remote interaction with simple Artificial Intelligence – A.I. capabilities or sophisticated control of their robotic artefacts. At this moment, trainers should be able to propose simple and stable techniques to their students for implementing such features in their constructions. This paper proposes flexible methods for this to be done by exploiting the very popular MIT App Inventor and Snap! visual programming environments, in conjunction with a modified tiny web server module, written in Python, that runs on a Raspberry Pi credit card - sized computer. Furthermore, this paper reports on simple techniques being used to make robust enough robots by low cost everyday/recyclable materials like cardboard, wood, plastic bottles or broken toys