Protection of Sensitive Data: Creating, Analyzing and Testing Protocols of Differential Privacy

Το πρόβλημα της διατήρησης της ιδιωτικότητας κατά την ανάλυση δεδομένων, υφίσταται για πολύ καιρό. Συγκεκριμένα, στην εποχή των big­data, λεπτομέρειες των χρηστών μπορούν εύκολα να παραβιαστούν από κακόβουλους χειριστές των δεδομένων, γεγονός που θεωρείται ζήτημα τόσο όσον αφορά την ασφάλεια, όσο και την προστασία της ιδιωτικότητας του ατόμου. Mε την υπάρχουσα κατάσταση, υπάρχει η απλή λύση της άρνησης της πρόσβασης σε δεδομένα χρηστών, στον βωμό της προστασίας τους, κάτι που καθιστά την εξαγωγή συμπερασμάτων για ποικίλα θέματα αδύνατη. Από την άλλη, ένας επιτυχημένος μηχανισμός θα ήταν η ελεύθερη διακίνηση των δεδομένων, χωρίς φιλτράρισμά τους, γεγονός που θα ήταν ωφέλιμο για την πρόοδο των επιστημών (λόγω του μεγάλου όγκου δεδομένων που θα ήταν διαθέσιμος), αλλά μία μεγάλη παραβίαση της ιδιωτικότητας των ατόμων. Ωστόσο, καμία από τις δύο αυτές λύσεις δεν μπορεί να εφαρμοστεί και να μας βοηθήσει στην επίλυση τους προβλήματός μας. Η απάντηση είναι η εύρεση μίας ισορροπίας, η οποία ευνοεί και τα δύο μέρη: τους χρήστες και την ιδιωτικότητά τους, όπως και τους ερευνητές. Η βέλτιστη επίλυση του θέματος, είναι η Διαφορική Ιδιωτικότητα, που στην πραγματικότητα πρόκειται για μία υπόσχεση από τον χειριστή των δεδομένων προς τον χρήστη, πως ο χρήστης δεν θα επηρεαστεί αν επιτρέψει τη χρήση των δεδομένων του σε κάποια ανάλυση, χωρίς περιορισμούς όπως η παράλληλη ύπαρξη άλλων μελετών/βάσεων δεδομένων πληροφοριών που υπάρχουν για αυτόν. Παράλληλα, τα στατιστικά του αποτελέσματος της ανάλυσης, πρέπει να είναι αρκετά ακριβή, ώστε ο ερευνητής να μπορεί να εξάγει χρήσιμη πληροφορία από αυτά. Η υπόσχεση αυτή, δείχνει δύσκολα υλοποιήσιμη με την πρώτη ματιά. Παρόλα αυτά, σε αυτήν την πτυχιακή εργασία, θα ερευνήσουμε με λεπτομέρεια τη θεωρία που καθιστά εφικτή αυτή τη μορφή ιδιωτικότητας, με την προσθήκη τυχαίου θορύβου στα δεδομένα. Η Διαφορική Ιδιωτικότητα βασίζεται σε πιθανοτικές κατανομές, γνωστές ήδη από τον 20o αιώνα, όμως παραμένει μία νέα τεχνική, η οποία δεν έχει πλήρως υλοποιηθεί με τρόπο τέτοιον ώστε να μπορεί να χρησιμοποιηθεί από πολλούς ανθρώπους που είναι υπεύθυνοι για την εξαγωγή δεδομένων. Σκοπός αυτής της πτυχιακής εργασίας, είναι να μελετήσουμε και να συγκρίνουμε ήδη υλοποιημένους μηχανισμούς πανω στην Δ.Ι., ενώ παράλληλα θα δημιουργήσουμε τον δικό μας μηχανισμό, ο οποίος χρησιμοποιείται για τους σκοπούς της Τοπικής Διαφορικής Ιδιωτικότητας που συναντάται την σήμερον ημέραν σε αλγορίθμους μηχανικής μάθησης, με στόχο να προστατέψει τα δεδομένα που αποστέλλουν για εκμάθηση οι χρήστες. Θα το κατορθώσουμε αυτό δημιουργώντας μία προγραμματιστική βιβλιοθήκη η οποία είναι εύκολη στη χρήση, ικανοποιώνατας παράλληλα τους κανόνες της προστασίας δεδομένων, και τέλος θα εξάγουμε συμπεράσματα από τη χρήση της βιβλιοθήκης αυτής. Κατά την διάρκεια αυτής της εργασίας, θα πραγματοποιηθούν πολλές μετρήσεις, με στόχο να γίνει πειστική η χρησιμότητα και η αποτελεσματικότητα της Διαφορικής Ιδιωτικότητας.The problem of preserving privacy while extracting information during data analysis, has been an everlasting one. Specifically, during the big­data era, user details can be easily compromised by a malicious handler, something considered both as a security, and as a privacy issue. With that being the case, there is a simple solution of denying the access to user data, thus making the mining of useful information about a plethora of subjects impossible. On the other hand, a successful mechanism would be for the data to be flowing without control, something that would be beneficiary for the advance of sciences (because of the huge amount of information that would be available), but a significant compromisation for the individuals’ privacy. However, none of these two solutions are applicable and helpful for solving our problem. The answer is finding a balance, that would benefit both parties: the users and their privacy, as well as the researchers. The optimal fix to the subject, is Differential Privacy, which is actually a promise, made by the data handler to the user, that they will not be affected, by allowing their data to be used in any analysis, no matter what other studies/databases/info resources are available. Meanwhile, the output data statistics should be accurate enough for any researcher to extract useful information from them. This is a promise that in the first sight, seems rather hard to be achieved. Despite that, during this thesis, we will look closely into the theory which makes this form of privacy possible, by the addition of random noise to the user data. Differential Privacy is based on probabilistic theories, well known from the 20th century, however, it is a rather new technique, which has yet to be fully implemented in a handy way for all data­miners to use. The goal of this thesis, is to examine and compare previously created mechanisms for D.P., while also creating our own mechanism, that serves to the purpose of achieving Local D.P., a form of Differential Privacy that is nowadays widely used in machine learning algorithms, aiming to protect the individuals that send their personal data for analysis. We will do so, by creating a library that is easy to use, and applies to all the rules of data privacy, and then extract conclusions from its use. During this thesis, a lot of testings will be made, in order to convince for the usability and the efficiency of Differential Privacy

Η διαχείριση των εναέριων μέσων δασοπυρόσβεσης στο διεθνή χώρο και η επιχειρησιακή αξιοποίηση τους στην Ελλάδα

Ο άνθρωπος πάντοτε χαρακτηριζόταν από την καινοτομία και την προσαρμογή στο φυσικό περιβάλλον. Η προσαρμογή αυτή, σε συνδυασμό με την εμπειρία και την παρατήρηση, τον βοήθησε να εξελιχθεί και να οργανωθεί σε κοινωνικές ομάδες. Η αρμονική συμβίωση με το περιβάλλον και η εκμετάλλευση των φυσικών πόρων οδήγησε την ανθρωπότητα στην πολιτισμική και τεχνολογική εξέλιξη. Η ανακάλυψη και η χρήση της φωτιάς αποτέλεσε ένα από τα σημαντικότερα επιτεύγματα του ανθρώπινου γένους. Μέσω αυτής της ανακάλυψης, κατόρθωσε να επεκτείνει τη γνώση του και να προσαρμοστεί σε συνθήκες όπου το περιβάλλον δεν ήταν ανεκτό για τον ανθρώπινο οργανισμό. Η τεχνολογική εξέλιξη μέσω της φωτιάς οδήγησε αναπόφευκτα και στη βιομηχανική επανάσταση. Ταυτόχρονα, η σχέση του ανθρώπου με τη φωτιά μεταλλάχθηκε από σχέση ανάγκης και συμβίωσης σε σχέση απειλής. Η απειλή από την ανεξέλεγκτη δράση της φωτιάς ώθησε τον άνθρωπο στη δημιουργία δομών και μονάδων για την καταστολή της και την προφύλαξη της κοινωνίας. Η έννοια της πυρόσβεσης, αν και διατυπώθηκε αρχικά κατά την περίοδο της ρωμαϊκής αυτοκρατορίας, ουσιαστικά καθιερώθηκε κατά τον 17ο αιώνα σε διάφορες χώρες. Η εξέλιξη αυτή αναλύεται στο πρώτο κεφάλαιο, σε συνδυασμό με το μηχανισμό έναρξης και επέκτασης της φωτιάς και των στρατηγικών και τακτικών που ακολουθούνται ευρέως για τη διακοπή της μετάδοσης της. Ο όρος «κλιματική αλλαγή» είναι κάτι που ακούγεται συχνότερα τα τελευταία 30 έτη. Η προσπάθεια του Κέππεν στα τέλη του 19ου αιώνα να κατηγοριοποιήσει τις περιοχές του πλανήτη ανάλογα με τις κλιματικές συνθήκες που επικρατούσαν, εισήγαγε την έννοια του μεσογειακού κλίματος. Περιοχές του πλανήτη οι οποίες μοιράζονταν χαρακτηριστικά στη χλωρίδα και στο κλίμα με τη μεσογειακή λεκάνη. Πάνω σε αυτές τις περιοχές βασίστηκε η διατριβή αυτή, αναφορικά με τη διαχείριση των εναέριων μέσων. Οι δασικές πυρκαγιές αποτελούν μια καταστροφική εκδοχή της κλιματικής αλλαγής και η επιρροή του κλίματος εξετάζεται στο δεύτερο κεφάλαιο. Στο τρίτο κεφάλαιο αναλύονται οι τακτικές και οι στρατηγικές διαχείρισης των εναέριων μέσων. Η ιστορική αναδρομή της αεροπυρόσβεσης αποδεικνύει τη διαπίστωση του ανθρώπου πως τα εναέρια μέσα μπορούν να χρησιμοποιηθούν αποτελεσματικά στη δασοπυρόσβεση. Γίνεται αναφορά σε πέντε χώρες που διακατέχονται από μεσογειακό κλίμα, για να γίνει κατανοητή η προσέγγιση που έχει η καθεμία στη διαχείριση των εναέριων μέσων δασοπυρόσβεσης, έχοντας ως κοινό παρονομαστή την ομοιότητα στις κλιματικές συνθήκες. Στο τέταρτο κεφάλαιο διατυπώνονται τα συμπεράσματα και οι προτάσεις αναφορικά με τα δεδομένα της επιχειρησιακής δράσης των εναέριων μέσων δασοπυρόσβεσης. Η εξέλιξη της αεροπυρόσβεσης αποτελεί ένα στρατηγικό στόχο των ανεπτυγμένων χωρών. Η επιχειρησιακή δράση των μέσων κατά τις νυχτερινές ώρες είναι ο βασικότερος πυλώνας τεχνολογικής εξέλιξης και το μεγαλύτερο μέρος της έρευνας επικεντρώνεται σε αυτό το πλαίσιο. Πέρα από τα αεροσκάφη και ελικόπτερα, στη δράση της αεροπυρόσβεσης έχουν ενταχθεί και τα μη επανδρωμένα αεροσκάφη, με διάφορες σκέψεις και ιδέες να αναπτύσσονται στον τομέα αυτό.Human has always been identified by innovation and adaptation to the natural environment. This adaptation, combined with experience and observation, helped him to evolve and organize into social groups. The harmonious coexistence with the environment and the exploitation of natural resources, led humanity to cultural and technological development. The discovery and use of fire was one of the most important achievements of the human race. Through this discovery, human was able to expand his knowledge and adapt to conditions where the environment was not tolerable for the human body. Technological development through fire, inevitably led to the industrial revolution. At the same time, human's relationship with fire changed from a relationship of necessity and coexistence to a relationship of threat. The threat of uncontrolled action of fire pushed human to create structures and units for its suppression and the protection of society. The concept of firefighting, although originally formulated during the Roman Empire, was essentially introduced in the 17th century in various countries. This development is analyzed in the first chapter, in combination with the mechanism of initiation and expansion of fire and the strategies and tactics that are widely followed to stop its transmission. The term "climate change" is something that has been heard more often in the last 30 years. Köppen’s attempt at the end of the 19th century to categorize the regions of the planet according to the prevailing climatic conditions, introduced the concept of the Mediterranean climate. Areas of the planet that were typically shared in flora and climate with the Mediterranean basin. This dissertation was based on these areas, regarding the management of air resources. Forest fires are a devastating version of climate change, and the effects of climate change are discussed in Chapter Two. The third chapter analyzes the tactics and strategies of aircraft management. The historical background of aerial firefighting proves the human realization that aerial means can be used effectively in forest firefighting. Reference is made to five countries with a Mediterranean climate, in order to understand the approach that each has to the management of aerial firefighting equipment, having as a common denominator the similarity in climatic conditions. In the fourth chapter are presented the conclusions and proposals regarding the data of the operational action of the aerial means of forest firefighting. The evolution of firefighting is a strategic goal of developed countries. The operational activity of the media at night is the main pillar of technological development and most of the research focuses on this context. In addition to aircraft and helicopters, unmanned aerial vehicles have also joined the firefighting operation, with various thoughts and ideas being developed in this field

Sodium valproate as a cause of recurrent transudative pleural effusion: a case report

INTRODUCTION: There are few reported cases of neutrophilic pleural effusions associated with valproic acid therapy. Most of them are of eosinophilic exudates with or without blood eosinophilia. CASE PRESENTATION: This case study describes a 70-year-old man with recurrent episodes of eosinophilic transudative pleural effusions associated with sodium valproate treatment. The recurrence of effusion after re-administration of the drug is strongly suggestive of an association between them. To the best of our knowledge, this is the first reported case with a pleural effusion with these characteristics caused by sodium valproate. CONCLUSION: This is the first report in the literature, with a full understanding of the etiology but with an unknown drug mechanism. This case report is of interest to different medical specialists (such as pulmonologists, neurologists, cardiologists) and pharmacologists

Effects of parental support and coach-initiated motivational climate on young athletes’ psychosocial behaviors and well-being

This study examined the effect of coach-initiated motivational climate and parental support on intrinsic motivation, enjoyment of sport participation, subjective vitality, sport-related violence, and academic achievement of youth soccer players. The second purpose was to examine if intrinsic motivation mediates the impact of coach-initiated climate and parental support on the above endogenous variables. Two measurements Time 1 (T1) and Time 2 (T2) were conducted. In T1, 494 young soccer male athletes completed surveys of coach-created motivational climate, parental praise and understanding, intrinsic motivation, sport-related violence, vitality, sport enjoyment and Grade Point Average (GPA). After five months, 188 of those soccer athletes responded again to the same surveys (T2). In both measurements the findings suggest that perceived coach-initiated empowering climate and parental praise and understanding have indirect effects on sport-related violence, GPA, vitality and sport enjoyment through intrinsic motivation in sport.publishedVersio

Analyzing Moodle/LMS logs to measure mobile access

Most Educational Institutions worldwide have deployed web based Learning Management Systems (LMS) as a means to provide support for their presence-based lectures and offer online-exclusive learning. These LMSs were designed and developed for users accessing the system through web browsers on desktop computers or laptops. However, over the last years, an increasing percentage of the registered accesses to various LMS platforms have been from mobile devices such as smartphones. While tackling the problems arising through the design of a mobile client for the Open Source LMS Moodle called Moodbile, the question of how to decide which services of Moodle could be accessed from smartphones became very relevant. This paper presents a data analysis study conducted on the Moodle server logs of the Universitat Politècnica de Catalunya-Barcelona Tech (UPC) virtual campus, Atenea, and the insight gained regarding the particular characteristics of the accesses from mobile devices. The main achievement of this study is that it provides insight of the use of the university LMS from mobile devices.Peer ReviewedPostprint (published version

Considering a pull mechanism for an informal learning activities collector

There is a recent interest in the research of Lifelong Learning and other related kinds of learning (formal, non-formal and informal). Some projects have been held in order to propose frameworks for managing all these types of learning, giving special attention to the informal learning. The TRAILER project is one of them. It supports the identification and management of informal learning activities. It gathers informal learning activities with an Informal Learning Collector (ILC) and a Portfolio is used to make visible how much a learner acquires informal learning. The main way for registering informal learning activities data into the ILC is using push mechanisms where the users explicitly introduce such information. In this paper, we propose an alternative way to register information about informal learning activities, but using a pull mechanism, where the ILC collects data from external applications. In this sense, we improve ILC usability.Peer ReviewedPostprint (author’s final draft

The Perioperative Use of Levosimendan as a Means of Optimizing the Surgical Outcome in Patients with Severe Heart Insufficiency Undergoing Cardiac Surgery.

BACKGROUND Postoperative myocardial dysfunction following cardiac surgery is a relatively common occurrence. Levosimendan, a calcium sensitizer and inotropic drug, has shown potential in improving outcomes for patients with low preoperative ejection fraction (EF) and myocardial dysfunction after cardiac surgery. This study aims to evaluate the efficacy of levosimendan in optimizing the surgical outcome for such patients. METHODS A retrospective analysis was conducted on 314 patients with preoperative severe heart failure who underwent cardiac surgery. Among them, 184 patients received perioperative adjunctive therapy with levosimendan, while a comparable group of 130 patients received conventional treatment. RESULTS The use of levosimendan demonstrated several advantages in postoperative outcomes. It significantly improved short- and long-term survival rates after cardiac surgery, enhanced hemodynamic stability, reduced the requirement for inotropic support, and facilitated faster weaning from ventilator support. Patients who received levosimendan reported reduced angina and dyspnea symptoms, as well as fewer postoperative arrhythmias. Furthermore, levosimendan helped minimize myocardial injury inevitable after cardiac surgery. The levosimendan group also exhibited a notable reduction in hospital readmissions. CONCLUSIONS This study provides evidence of several benefits associated with the perioperative use of levosimendan. However, further prospective randomized studies are warranted to standardize and comprehensively document the other perioperative therapies, in order to validate these findings and establish stronger conclusions

Coupling and Decoupling Relationships between Energy Consumption and Air Pollution from the Transport Sector and the Economic Activity

In the present paper an analysis of whether and under which conditions coupling or decoupling exists between growth rates (as reflecting in GDP rates) of the economy and energy consumption and air pollution from the transport sector. An extensive time period from 1995 to 2012 is surveyed and divided into two periods, from 1995 to 2008 (growth period) and from 2008 to 2012 (recession period). The analysis is conducted for the 28 European Union countries and illustrates, for most of these countries, a coupling phenomenon for the growth period and a decoupling phenomenon for the recession period. This finding may be essential for the further institutional steps to be undertaken, in view of the reduction of CO2 and of energy conservation. Keywords: Coupling; Decoupling; Transportation; Environment; Sustainability JEL Classifications: H23; O44; R4; Q53

Perioperative Application of Levosimendan Optimizes Postoperative Renal Function and Organ Perfusion in Patients with Severe Heart Failure.

Background: Renal dysfunction and impaired organ perfusion are common concerns following cardiac surgery. Levosimendan, a calcium sensitizer inotropic drug, is investigated in this study for its potential to improve postoperative renal function and organ perfusion in patients with low preoperative ejection fraction and severe myocardial dysfunction after cardiac surgery. Methods: A retrospective analysis was conducted on 314 patients with preoperative heart failure who underwent cardiac surgery. Among them, 184 patients received perioperative adjunctive therapy with levosimendan, while 130 patients with similar characteristics received conventional treatment. Results: The perioperative administration of levosimendan resulted in a significantly lower need for renal replacement therapy (p < 0.001) and improvements in the serum creatinine levels, glomerular filtration rate, and creatinine clearance. Similarly, the C-reactive protein levels, blood pH, and lactic acid levels showed comparable improvements. Conclusions: The use of levosimendan was associated with a significant enhancement in postoperative renal function and a reduction in the need for renal replacement therapy. Furthermore, it resulted in a decrease in the extent of organ malperfusion. Postoperative inflammatory reactions and metabolic balance also exhibited improvements

Extending Moodle services to mobile devices: The Moodbile Project

Learning Management Systems (LMS) are widespread among most education and training institutions. Even though LMS are a mature technology, they have left the vanguard of innovation in e-learning to mobile devices and tablets. Mobile Learning (M-learning)may enhance e-learning by increasing communication and conversation opportunities to convents the learning process more collaborative and learner-centred. This paper describes a way to integrate mobile devices and educational applications with a LMS as Moodle through web services: The Moodbile Project. Rather than just creating mobile apps that replicates LMS functionalities on a mobile device, Moodbile provides to m-learning developers with the necessary tools to allow mobile devices to interact with the LMS. In this paper, we describe our proposal of an open specification of web services to support the integration of mobile external applications with Moodle.Peer ReviewedPostprint (published version