cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Μελέτη της εξέλιξης του διανύσματος κατάστασης μη ομογενών μαρκοβιανών αλυσίδων σε συνεχή χρόνο
Creators: name: Μπότσας, Θεμιστοκλής Γεωργίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Μαρκοβιανές διαδικασίες
Διάνυσμα κατάστασης
Διαφορικές εξισώσεις Kolmogorov
Markov processes
State vector
Kolmogorov differential equations

description: Οι Μαρκοβιανές αλυσίδες είναι στοχαστικά μοντέλα που έχουν ως βάση τους τη Μαρκοβιανή ιδιότητα. Χρησιμοποιούνται στη μοντελοποίηση εφαρμογών σε πάρα πολλούς τομείς με σκοπό τη μελέτη και την εξαγωγή συμπερασμάτων. Στα πλαίσια της παρούσας εργασίας μελετάμε το ρυθμό σύγκλισης του πίνακα μετάβασης και του διανύσματος κατάστασης μιας μαρκοβιανής αλυσίδας συνεχούς χρόνου για τη μη-ομογενή περίπτωση. Συγκεκριμένα, εστιάζουμε στην επίλυση του συστήματος διαφορικών εξισώσεων των προς τα πίσω διαφορικών εξισώσεων του Kolmοgorov. Για το σκοπό αυτό, χρησιμοποιούνται μεθοδολογίες της θεωρίας πινάκων, με βάση τον βασικό πίνακα (matricant) ή εναλλακτικά την ολοκληρωτική εξίσωση Volterra 2ου είδους. Αρχικά εξετάζεται ο ρυθμός σύγκλισης των πινάκων μετάβασης της μαρκοβιανής αλυσίδας και στη συνέχεια των διανυσμάτων κατάστασης. Κατόπιν προσδιορίζουμε τη λύση του συστήματος διαφορικών εξισώσεων με τη βοήθεια προσεγγιστικών μεθόδων, για χαρακτηριστικές περιπτώσεις του πίνακα τάσης. Επίσης γίνεται μελέτη της ασυμπτωτικής συμπεριφοράς των παραπάνω συστημάτων. Τέλος, επιβεβαιώνουμε και συγκρίνουμε τα παραπάνω αποτελέσματα με τη χρήση κώδικα και γραφημάτων με τη βοήθεια του πακέτου προγραμματισμού MATLAB.
description: Markov chains are stochastic models based on the Markov identity. They are used in modeling applications in many fields in order to study them and draw conclusions.βIn the present work we study the rate of convergence of the transition matrix and the state vector of a continuous time Markov chain on the non-homogeneous case. Specifically, we focus on solving the system of the backward Kolmogorov differential equations. For this purpose, we use methodologies of matrix theory, based on the matricant or alternatively the Volterra integral equation of the second kind. Firstly, we examine the rate of convergence of the transition matrix of the Markov chain and the associated state vector. Then we define the solution of the system of differential equations by means of certain typical intensity matrices. Also we study the asymptotic behavior of those systems. Finally, we confirm and compare these results by means of codes and graphs using the programming package MATLAB.
Information-theoretic temporal Bell inequality and quantum computation
Creators: name: Morikoshi, Fumiaki
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: An information-theoretic temporal Bell inequality is formulated to contrast classical and quantum computations. Any classical algorithm satisfies the inequality, while quantum ones can violate it. Therefore, the violation of the inequality is an immediate consequence of the quantumness in the computation. Furthermore, this approach suggests a notion of temporal nonlocality in quantum computation.
description: v2: 5 pages, refereces added, discussion slightly revised, main result unchanged. v3: typos corrected
What is (not) wrong with scalar gravity?
Creators: name: Giulini, Domenico
Publisher: name: arXiv
Year: 2006
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: On his way to General Relativity (GR) Einstein gave several arguments as to why a special relativistic theory of gravity based on a massless scalar field could be ruled out merely on grounds of theoretical considerations. We re-investigate his two main arguments, which relate to energy conservation and some form of the principle of the universality of free fall. We find that such a theory-based a priori abandonment not to be justified. Rather, the theory seems formally perfectly viable, though in clear contradiction with (later) experiments. This may be of interest to those who teach GR and/or have an active interest in its history.
description: 26 pages, 3 figures
Cost Models for Database Queries in Cloud Environments
Creators: name: Καράμπαγλης, Ζήσης Αθανασίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Οικονομικό κόστος
Περιβάλλοντα νέφους
Monetary cost
Cloud environment

description: Τα μοντέλα κόστους χρησιμοποιούνται ευρέως στην επεξεργασία ερωτημάτων για διάφορες εφαρμογές, μερικές από τις οποίες είναι η διαδικασία βελτιστοποίησης ερωτημάτων, η ακριβής πρόβλεψη του χρόνου εκτέλεσης τους, ο χρονοπρογραμματισμός εργασιών και ο έλεγχος απόδοσης ερωτημάτων βάσεων δεδομένων, όπως και η άντληση των απαιτούμενων πόρων για την εκτέλεση ερωτημάτων. Ο κύριος ρόλος των μοντέλων κόστους είναι η πρόβλεψη του απαιτούμενου χρόνου για την εκτέλεση ενός ερωτήματος σε ένα συγκεκριμένο μηχάνημα. Σε περιβάλλοντα νέφους αυτό είναι ανεπαρκής, αφενός γιατί τα μηχανήματα που χρησιμοποιούνται δεν είναι γνωστά εκ των προτέρων και αφετέρου γιατί η προβλέψεις του χρόνου εκτέλεσης πρέπει να συμπληρώνονται και από το κόστος εκτέλεσης, διότι τόσο το οικονομικό κόστος όσο και η απόδοση είναι πρωταρχικής σημασίας. Η παρούσα διπλωματική εργασία ασχολείται με τις δύο αυτές ελλείψεις και έχει ως στόχο να χρησιμεύσει ως μια πρώτη πρόταση για ένα μοντέλο κόστους που είναι κατάλληλο για ερωτήματα που εκτελούνται σε περιβάλλοντα νέφους που παρέχονται από δυνητικά πολλαπλούς παρόχους. Επιπλέον, η προσέγγισή μας μπορεί να εφαρμοστεί σε πιο γενικούς γράφους ροής δεδομένων, τα σχέδια εκτέλεσης των οποίων δεν περιλαμβάνουν απαραιτήτως σχεσιακούς τελεστές. Ενα μεγάλο μέρος αυτής την δουλειάς θα δημοσιευτεί στο διεθνές συνέδριο Management of computational and collEctive intelligence in Digital EcoSystems 2014 (MEDES’14, September 15-17, 2014).
description: Cost models are broadly used in query processing to drive the query optimization process, accurately predict the query execution time, schedule database query tasks and apply admission control, or derive resource requirements to name a few applications. The main role of cost models is to produce the time needed to run the query on a speciﬁc machine. In a multi-cloud environment, this is insufficient in two aspects: ﬁrstly, the machines employed are not deﬁned a-priori, and secondly, time estimates need to be complemented with monetary cost information, because both the economic cost and the performance are of primary importance. This master’s thesis addresses these two shortcomings and aims to serve as the ﬁrst proposal for a bi-objective query cost model that is suitable for queries executed over resources provided by potentially multiple cloud providers. Moreover, our approach is applicable to more generic data ﬂow graphs, the execution plans of which do not necessarily comprise relational operators. A big part of this work is going to be published in the international conference on Management of computational and collEctive intelligence in Digital EcoSystems 2014 (MEDES’14, September 15-17, 2014).
Blocking Adversarial Influence in Social Networks
Creators: name: Jia, Feiran
name: Zhou, Kai
name: Kamhoua, Charles
name: Vorobeychik, Yevgeniy
Publisher: name: arXiv
Year: 2020
Subjects: subject: Social and Information Networks (cs.SI)
subject: Computer Science and Game Theory (cs.GT)
subject: FOS: Computer and information sciences

description: While social networks are widely used as a media for information diffusion, attackers can also strategically employ analytical tools, such as influence maximization, to maximize the spread of adversarial content through the networks. We investigate the problem of limiting the diffusion of negative information by blocking nodes and edges in the network. We formulate the interaction between the defender and the attacker as a Stackelberg game where the defender first chooses a set of nodes to block and then the attacker selects a set of seeds to spread negative information from. This yields an extremely complex bi-level optimization problem, particularly since even the standard influence measures are difficult to compute. Our approach is to approximate the attacker's problem as the maximum node domination problem. To solve this problem, we first develop a method based on integer programming combined with constraint generation. Next, to improve scalability, we develop an approximate solution method that represents the attacker's problem as an integer program, and then combines relaxation with duality to yield an upper bound on the defender's objective that can be computed using mixed integer linear programming. Finally, we propose an even more scalable heuristic method that prunes nodes from the consideration set based on their degree. Extensive experiments demonstrate the efficacy of our approaches.
Η αυτοαποκαλούμενη διακριτική ευχέρεια του δικαστή
Creators: name: Βεττού, Αναστασία Βασιλείου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Διακριτική ευχέρεια
Ηθική βλάβη
συντρέχον πταίσμα
προδικαστική απόφαση
Discretionary power
non-pecuniary damage
contributory fault
prejucative decision

description: Η παρούσα μελέτη πραγματεύεται το ζήτημα της αποκαλούμενης «διακριτικής ευχέρειας» του δικαστή αποσκοπώντας να εγείρει προβληματισμούς στο κατά πόσον ο δικαστής σε συγκεκριμένες επίδικες υποθέσεις έχει περιθώριο για άσκηση διακριτικής εξουσίας, όπως διατείνεται η κρατούσα νομολογία, τόσο των πολιτικών, όσο και των διοικητικών δικαστηρίων, ή μάλλον κατά την ορθότερη άποψη οφείλει να στοιχίζεται στο θετικό δίκαιο και στις αρχές του δικαίου αιτιολογώντας τις δικαστικές αποφάσεις μέσα στο πλαίσιο αυτό. Το ζήτημα αυτό δεν είναι θεωρητικού ενδιαφέροντος , καθόσον έχει άμεσες πρακτικές συνέπειες. Συγκεκριμένα, η <> του δικαστή δεν υπόκειται σε αναιρετικό έλεγχο, γεγονός που συνάπτεται με ζητήματα δίκαιης δίκης, καθώς και αποτελεσματικής και πλήρους δικαστικής προστασίας. Πέρα όμως από την πάγια νομολογία, ενδεχόμενη μεταστροφή της οποίας είναι ευκταία, και σε νομοθετικό επίπεδο είναι επιβεβλημένη, η καθιέρωση αντικειμενικών κριτηρίων στα οποία να εδράζεται η δικανική κρίση, ώστε να μην καταλείπεται έδαφος για διακριτική ευχέρεια. Στο πρώτο κεφάλαιο επιχειρείται η ανάλυση του ζητήματος σε θεωρητικό επίπεδο, με αναφορές κυρίως στην ξενόγλωσση βιβλιογραφία , ένω στο δεύτερο κεφάλαιο εξέταζεται από νομολογιακή άποψη κατά πόσο είναι όντως ευχέρεια ή αντίθετα δέσμια αρμοδιότητα.
description: This thesis regards the legal issue of the so called discretionary power of the judje, aiming to raise concerns on whether judges in certain disputed cases have the right to exert discretionary power as the settled case-law upholds, ( both administrative and civil justice), or are obliged to stick to positive law. This legal issue is not of theoretical interest, as it has direct practical impact. In particular, the judjement, which is exercised with discretionary power is not subject to annulment control, which in fact correlates with issues of fair trial anf effective full legal protection. Beyond the settled case-law, a potential reform of which is desirable, in legislative level the establishment of objective criteria is imperative so as the judicial decision is based on them, so it exists no margin for discretionary power.
Automating Hate: Exploring Toxic Reddit Norms with Google Perspective
Creators: name: Chevrier, Nicholas
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 2022
Subjects: Automated Moderation
Governance
Reddit
Google Perspective
Toxicity

description: The Canadian Online Harms Legislation (COHL) proposal identifies proactive Automated Moderation as a solution to classifying and removing online content which violates norms such as hate. Emerging automated moderation algorithms include Google Perspective, a machine learning model which scores hateful features in text content as “toxicity.” This study identifies that hateful community content norms are currently emerging on volunteer user moderation platforms such as Reddit. To operationalize these concepts, a Theoretical Framework is constructed using Gorwa’s (2019) Platform Governance models and Massanari’s (2017) overview of Toxic Technoculture communities. While previous research exploring community toxicity is discussed, there is a gap in research which analyzes the Post, Comment, and Image Meme contributions of Reddit Moderator users to hateful community content norms. As such, an analysis of the Reddit community R/Metacanada is constructed which compares the toxicity of Moderator and user contributions using Google Perspective. The results of the applied Mann-Whitney U test analysis indicate that r/Metacanada Moderators and users contribute content at similar toxicity levels. Supplementing these tests, RQ1 then structures a qualitative analysis of false negative results which may emerge in the automated classification of multi-modal image content. Identifying that hate in online memes is structured through layered Signifier and Signified elements, a critical discussion is established which interprets potential marginalizing effects of the COHL’s automated moderation applying Noble’s (2018) theory of Technological Redlining. As such, this thesis immerses itself within the contemporary context of online content regulation, drawing upon existing conceptualizations and methodological approaches, offering a critical discussion of regulating hate content using automated algorithms.
Asymptotic compactness in topological spaces
Creators: name: Nishiguchi, Junya
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Topology (math.GN)
subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: Primary 54A20, 54D30, 54E15, Secondary 37B02, 54C60

description: The omega limit sets plays a fundamental role to construct global attractors for topological semi-dynamical systems with continuous time or discrete time. Therefore, it is important to know when omega limit sets become nonempty compact sets. The purpose of this paper is to understand the mechanism under which a given net of subsets of topological spaces is compact in the asymptotic sense. For this purpose, we introduce the notion of asymptotic compactness for nets of subsets and study the connection with the compactness of the limit sets. In this paper, for a given net of nonempty subsets, we prove that the asymptotic compactness and the property that the limit set is a nonempty compact set to which the net converges from above are equivalent in uniformizable spaces. We also study the sequential version of the notion of asymptotic compactness by introducing the notion of sequentiality of directed sets.
description: 28 pages
Σύνδρομο Asperger και εκπαιδευτική ρομποτική: πιλοτική παρέμβαση με τη χρήση μικρών δομημένων προβλημάτων για τη βελτίωση μαθηματικών δεξιοτήτων
Creators: name: Νίκου, Αντωνία Ευαγγέλου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Σύνδρομο Ασπεργκερ
Εκπαιδευτική Ρομποτική
Ψυχαγωγική Εκπαίδευση
Asperger
Educational Robotics
Edutainment

description: Στόχος της διπλωματικής εργασίας ήταν η μελέτη του ρόλου που διαδραματίζει η εκπαιδευτική ρομποτική στην εκπαιδευτική διαδικασία της ειδικής αγωγής, ως εργαλείο μάθησης μαθηματικών δεξιοτήτων. Στο πρώτο μέρος επιχειρείται η ανασκόπηση της βιβλιογραφίας σχετικά με τον αυτισμό και το σύνδρομο Asperger. Παρουσιάζονται ορισμοί και χαρακτηριστικά, η επιδημιολογία αλλά και η αιτιολογία του αυτισμού και του συνδρόμου Asperger, καθώς και μέσα διάγνωσης, αλλά και η βιβλιογραφική ανασκόπηση σε σχέση με τη ρομποτική, τις εφαρμογές της στην εκπαίδευση και τη θετική ενίσχυση που μπορεί να επιτευχθεί μέσω αυτής σε άτομα με αυτισμό. Στο δεύτερο μέρος παρουσιάζεται η μεθοδολογική προσέγγιση που υιοθετήθηκε κατά την εκπόνηση αυτής της ερευνητικής εργασίας. Η παρούσα έρευνα έχει ως στόχο τη διερεύνηση της αποτελεσματικότητας μιας εκπαιδευτικής παρέμβασης, έχοντας ως εργαλείο εκμάθησης επίλυσης μαθηματικών προβλημάτων μία ρομποτική κατασκευή τύπου Lego Mindstorms από έναν μαθητή με σύνδρομο Asperger. Εφαρμόστηκε διδακτική προσέγγιση που συνδυάζει τη μάθηση με το παιχνίδι και υλοποιήθηκε με σενάρια βιωματικών δραστηριοτήτων.
description: The aim of this thesis was to study the role of educational robotics in the educational process of special education as a tool for learning math skills. The first part attempts to review the literature on autism syndrome Asperger. Featured definitions and characteristics, the epidemiology and etiology of autism and Down syndrome, Asperger, and diagnostic tools, as well as the literature review in relation to robotics applications in education and positive reinforcement can be achieved through this in people autism. Second part presents the methodological approach adopted in the preparation of this research. This research aims to investigate the effectiveness of an educational intervention as having learning tool solving mathematical problems one robotic Lego Mindstorms construction type of a student with Asperger. Applied teaching approach that combines learning with playing scenarios and implemented experiential activities.
description: Σε συνεργασία με το Παιδαγωγικό Τμήμα Νηπιαγωγών (Πανεπιστήμιο Δυτικής Μακεδονίας)
Pressure-driven flows in helical pipes: bounds on flow rate and friction factor
Creators: name: Kumar, Anuj
Publisher: name: arXiv
Year: 2020
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: In this paper, we use the well-known background method to obtain a rigorous lower bound on the volume flow rate through a helical pipe driven by a pressure differential in the limit of large Reynolds number. As a consequence, we also obtain an equivalent upper bound on the friction factor. These bounds are also valid for toroidal and straight pipes as limiting cases. By considering a two-dimensional background flow with varying boundary layer thickness along the circumference of the pipe, we obtain these bounds as a function of the curvature and torsion of the pipe and therefore capture the geometrical aspects of the problem. In this paper, we also present a sufficient criterion to find out which pressure-driven flow and surface-velocity-driven flow problems can be tackled using the background method.
description: Accepted for publication in the JFM
Modeling National Trends on Health in the Philippines Using ARIMA
Creators: name: Talirongan, Florence Jean B.
name: Talirongan, Hidear
name: Orong, Markdy Y.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: Health is a very important prerequisite in peoples well-being and happiness. Several studies were more focused on presenting the occurrence on specific disease like forecasting the number of dengue and malaria cases. This paper utilized the time series data for trend analysis and data forecasting using ARIMA model to visualize the trends of health data on the ten leading causes of deaths, leading cause of morbidity and leading cause of infants deaths particularly in the Philippines presented in a tabular data. Figures for each disease trend are presented individually with the use of the GRETL software. Forecasting results of the leading causes of death showed that Diseases of the heart, vascular system, accidents, Chronic lower respiratory diseases and Chronic Tuberculosis (all forms) showed a slight changed of the forecasted data, Malignant neoplasms showed unstable behavior of the forecasted data, and Pneumonia, diabetes mellitus, Nephritis, nephrotic syndrome and nephrosis and certain conditions originating in perinatal showed a decreasing patterns based on the forecasted data.
description: 6 pages, 11 figures, 3 tables, 1 formula
Η εξωτερική (διεθνής) μετανάστευση στις 27 χώρες της Ευρωπαϊκής Ένωσης
Creators: name: Ρίστα, Ελένη Γεωργίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Εξωτερική μετανάστευση
Στατιστική επεξεργασία
Xαρτογράφηση
International migration
Statistical analysis
Mapping

description: Σκοπός της διατριβής ήταν η μέτρηση του φαινομένου της μετανάστευσης στα 27 κράτη-μέλη της Ευρωπαϊκής Ένωσης, μέσα από μια σειρά στατιστικών μετρήσεων και αναλύσεων. Στόχος της εργασίας αποτέλεσε ο υπολογισμός κατάλληλων δεικτών που αφορούν στο φαινόμενο της μετανάστευσης και ο συσχετισμός τους με άλλες κοινωνικοοικονομικές μεταβλητές ώστε να γίνουν κατανοητοί οι λόγοι που οδηγούν κάποιον να μεταναστεύσει. Οι μεταβλητές αυτές ήταν το ποσοστό απασχόλησης, το ποσοστό ανεργίας, το ποσοστό ατόμων που διατρέχουν κίνδυνο φτώχειας ή κοινωνικού αποκλεισμού και το μέσο ετήσιο εισόδημα. Βασική επιδίωξη, επίσης, ήταν η χαρτογραφική αποτύπωση των στοιχείων που προέκυψαν από την ανάλυση, ώστε να εξαχθούν χρήσιμα συμπεράσματα για το σύνολο της Ευρωπαϊκής Ένωσης, αλλά και για κάθε χώρα χωριστά. Ως έτος αναφοράς επιλέχθηκε το 2008, λόγω έλλειψης πιο σύγχρονων στοιχείων για αρκετές χώρες και ως ηλικιακή κλάση αυτή των 25-54 ετών, εξ αιτίας του ότι στις ηλικίες αυτές είναι ελάχιστη η επίδραση μη οικονομικών λόγων μετανάστευσης, όπως είναι οι σπουδές και η συνταξιοδότηση. Επίσης, έγινε μια προσπάθεια να προσεγγιστεί η μετανάστευση στην κρίσιμη περίοδο της οικονομικής κρίσης με στοιχεία έως το 2011, ώστε να διερευνηθεί κατά πόσον όλες αυτές οι αλλαγές που συντελούνται σε οικονομικό και κοινωνικό επίπεδο επηρέασαν τις μεταναστευτικές τάσεις, τους μετανάστες, αλλά και τις χώρες προέλευσης και προορισμού τους.
description: The present thesis subject was to measure the international migration in the 27 Europe Union Members, through a series of statistical measurements and analyzes. The study aims to calculate relevant indicators related to the phenomenon of migration and their association with other socio-economic variables in order to understand the reasons that lead someone to migrate. These variables were: the employment rate, the unemployment rate, the percentage of people at risk of poverty or social exclusion and the average annual income. Basic goal was, also, the cartographic mapping of data resulting from the analysis in order to draw conclusions about the entire European Union, but also for each country separately. As baseline year was chosen 2008, due to lack of more modern data for several countries and as age class the 25-54 years, due to the fact that in these ages impact of non-economic reasons for migration, such as education and retirement is minimal. Special mention is made to how economic crisis affected the migration during the period 2002-2011, because migration is a demographic phenomenon, which is greatly influenced by the changing social and economic conditions of the countries that immigrants leave and enter.
Observations of the [CI] ($^3P_1$-$^3P_0$) emission toward the massive star-forming region RCW38: further evidence for highly-clumped density distribution of the molecular gas
Creators: name: Izumi, Natsuko
name: Fukui, Yasuo
name: Tachihara, Kengo
name: Fujita, Shinji
name: Torii, Kazufumi
name: Kamazaki, Takeshi
name: Kaneko, Hiroyuki
name: Silva, Andrea
name: Iono, Daisuke
name: Momose, Munetake
name: Sugimoto, Kanako
name: Nakazato, Takeshi
name: Kosugi, George
name: Maekawa, Jun
name: Takahashi, Shigeru
name: Yoshino, Akira
name: Asayama, Shin'ichiro
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present observations of the $^3P_1$-$^3P_0$ fine-structure line of atomic carbon using the ASTE 10 m sub-mm telescope towards RCW38, the youngest super star cluster in the Milky Way. The detected [CI] emission is compared with the CO $J$ = 1-0 image cube presented in Fukui et al. (2016) which has an angular resolution of 40$^{\prime \prime}$ ($\sim$ 0.33 pc). The overall distribution of the [CI] emission in this cluster is similar to that of the $^{13}$CO emission. The optical depth of the [CI] emission was found to be $τ$ = 0.1-0.6, suggesting mostly optically thin emission. An empirical conversion factor from the [CI] integrated intensity to the H$_2$ column density was estimated as $X_{\rm [CI]}$ = 6.3 $\times$ 10$^{20}$ cm$^{-2}$ K$^{-1}$ km$^{-1}$ s (for visual extinction: $A_V$ $\le$ 10 mag) and 1.4 $\times$ 10$^{21}$ cm$^{-2}$ K$^{-1}$ km$^{-1}$ s (for $A_V$ of 10-100 mag). The column density ratio of the [CI] to CO ($N_{\rm [CI]}/N_{\rm CO}$) was derived as $\sim$ 0.1 for $A_V$ of 10-100 mag, which is consistent with that of the Orion cloud presented in Ikeda et al. (2002). However, our results cover an $A_V$ regime of up to 100 mag, which is wider than the coverage found in Orion, which reach up to $\sim$ 60 mag. Such a high [CI]/CO ratio in a high $A_V$ region is difficult to be explained by the plane-parallel photodissociation region (PDR) model, which predicts that this ratio is close to 0 due to the heavy shielding of the ultraviolet (UV) radiation. Our results suggest that the molecular gas in this cluster is highly clumpy, allowing deep penetration of UV radiation even at averaged $A_V$ values of 100 mag. Recent theoretical works have presented models consistent with such clumped gas distribution with a sub-pc clump size (e.g., Tachihara et al. 2018).
description: 33 pages, 21 figures, PASJ accepted for publication
RISIS DATASETS TUTORIALS: CHEETAH
Creators: name: Department of Management, Economics and Industrial Engineering
Publisher: name: Zenodo
Year: 2019
Subjects: RISIS datasets
tutorials
CHEETAH
medium-sized firms

description: The Cheetah dataset contains geographical, industry, accounting and ownership information on three cohorts of medium-sized firms that experienced sales or employment fast growth rates in the periods 2008-2011, 2009-2012 and 2010-2013. These fast growing medium-sized firms (FGMFs) are located in 30 European countries (EU-28, Norway and Switzerland) plus Israel. Cheetah covers an overall number of 42,369 firms. The aim of Cheetah is to cover the long-term economic performance of FGMFs, as one of the main pillars of the European industrial and technological system.
When Should I Run My Application Benchmark?: Studying Cloud Performance Variability for the Case of Stream Processing Applications
Creators: name: Henning, Sören
name: Vogel, Adriano
name: Perez-Wohlfeil, Esteban
name: Ertl, Otmar
name: Rabiser, Rick
Publisher: name: arXiv
Year: 2025
Subjects: subject: Software Engineering (cs.SE)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Performance (cs.PF)
subject: FOS: Computer and information sciences

description: Performance benchmarking is a common practice in software engineering, particularly when building large-scale, distributed, and data-intensive systems. While cloud environments offer several advantages for running benchmarks, it is often reported that benchmark results can vary significantly between repetitions -- making it difficult to draw reliable conclusions about real-world performance. In this paper, we empirically quantify the impact of cloud performance variability on benchmarking results, focusing on stream processing applications as a representative type of data-intensive, performance-critical system. In a longitudinal study spanning more than three months, we repeatedly executed an application benchmark used in research and development at Dynatrace. This allows us to assess various aspects of performance variability, particularly concerning temporal effects. With approximately 591 hours of experiments, deploying 789 Kubernetes clusters on AWS and executing 2366 benchmarks, this is likely the largest study of its kind and the only one addressing performance from an end-to-end, i.e., application benchmark perspective. Our study confirms that performance variability exists, but it is less pronounced than often assumed (coefficient of variation of < 3.7%). Unlike related studies, we find that performance does exhibit a daily and weekly pattern, although with only small variability (<= 2.5%). Re-using benchmarking infrastructure across multiple repetitions introduces only a slight reduction in result accuracy (<= 2.5 percentage points). These key observations hold consistently across different cloud regions and machine types with different processor architectures. We conclude that for engineers and researchers focused on detecting substantial performance differences (e.g., > 5%) in...
description: 33rd ACM International Conference on the Foundations of Software Engineering (FSE 2025), Industry Track
Hidden activity in high-redshift spheroidal galaxies from mid-infrared and X-ray observations in the GOODS-North field
Creators: name: Rodighiero, G.
name: Gruppioni, C.
name: Civano, F.
name: Comastri, A.
name: Franceschini, A.
name: Mignoli, M.
name: Fritz, J.
name: Vignali, C.
name: Treu, T.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We exploit very deep mid-IR (MIR) and X-ray observations by Spitzer and Chandra in the GOODS North to identify signs of hidden (either starburst or AGN) activity in spheroidal galaxies between z~0.3 and 1. Our reference is a complete sample of 168 morphologically classified spheroidal galaxies with z[AB]<22.5 selected from GOODS ACS imaging. Nineteen of these have 24 micron detections in the GOODS catalogue, half of which have an X-ray counterpart in the 2 Ms Chandra catalogue, while about 25% have 1.4 GHz fluxes larger than 40 microJy. Traces of hidden activity in the spheroidal population are also searched for in the deep X-ray images and 14 additional galaxies are detected in X-rays only. The nature of the observed MIR emissions is investigated by modelling their SEDs based on the available multi-wavelength photometry, including X-ray, UV, optical, near-IR, MIR and radio fluxes, and optical spectroscopy. The amount of dust derived from the IR emission observed by Spitzer appears in excess of that expected by mass loss from evolved stars. Our analysis of the X-ray and MIR properties leads us to conclude that at least 8 of the 19 24-um bright sources should hide an obscured AGN, while the X-ray undetected sources are more likely dominated by star formation. [abridged] We conclude that ~30 objects (~20%) of the original flux-limited sample of 168 spheroidal galaxies in the GOODS-North are detected during phases of prominent activity, of both stellar and quasar origin. Due to the short expected lifetimes of the IR and X-ray emissions, this fraction might imply a significant level of activity in this class of galaxies during the relatively recent cosmic epochs, z~0.3 to z~1, under investigation.
description: Paper accepted for publication in MNRAS. A few figures have been degraded. A full resolution version can be found at http://www.astro.unipd.it/giulia/ELL/MN-06-0969-MJ.pdf
Δυνητικοί εαυτοί, εκπαιδευτικές και επαγγελματικές επιλογές εφήβων πριν και μετά το ξέσπασμα της οικονομικής κρίσης στην Ελλάδα.
Creators: name: Κοντάρα, Προκοπία Βασιλείου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: διαδικασίες μετάβασης στην ενήλικη ζωή
εκπαιδευτικές-επαγγελματικές επιλογές εφήβων
οικονομική κρίση
transitions to adulthood
adolescents’ educational and career choices
economic crisis

description: Η παρούσα εργασία αποσκοπεί στη μελέτη των πιθανών διαφορών στη διαδικασία μετάβασης από την εφηβεία στην ενήλικη ζωή, όπως αυτές αποτυπώνονται στις εκπαιδευτικές και επαγγελματικές επιλογές, αλλά και τις μελλοντικές αυτο-αναπαραστάσεις εφήβων μαθητών και μαθητριών της ελληνικής περιφέρειας σε δύο διαφορετικές χρονικές στιγμές: πριν και μετά το ξέσπασμα της οικονομικής κρίσης του 2008. Στο δείγμα συμμετείχαν 546 μαθητές και μαθήτριες ηλικίας 15 έως 17 ετών. Διαπιστώθηκαν στατιστικώς σημαντικές διαφορές όσον αφορά τη διαμόρφωση των προτιμήσεων των εφήβων κατά τις δύο εξεταζόμενες χρονικές στιγμές (αφορούσαν κυρίως το προτιμούμενο είδος εργασίας, την επιθυμία μετακίνησης στο εξωτερικό προς εύρεση εργασίας), αλλά και τις μελλοντικές αυτο-αναπαραστάσεις για τον εαυτό. Τέλος, αναδείχθηκε ο σημαντικός ρόλος του φύλου στη διαμόρφωση των υπό μελέτη μεταβλητών.
description: The present study intended to investigate possible differences between two groups of adolescent students at the transitional stage to adulthood, before and after the rise of the economic crisis (2008) in Greece. The transitional stage was examined through the variables of adolescents’ educational & career choices and also their personal aspirations of their future possible selves. A total of 546 students between 15 to 17 years of age participated in the study. The first group of students was examined before and the second after the rise of the economic crisis. Significant differences between the two groups were found as far as the preferred kind of job and the desire to move to another country in order to establish a career, are concerned. Moreover, significant differences between the two groups emerged for adolescents’ aspirations of their future possible selves. Finally, significant gender differences were noticed, in and between the two groups.
Classification of integrable super-systems using the SsTools environment
Creators: name: Kiselev, A. V.
name: Wolf, T.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: A classification problem is proposed for supersymmetric evolutionary PDE that satisfy the assumptions of nonlinearity and nondegeneracy. Four classes of nonlinear coupled boson-fermion systems are discovered under the homogeneity assumption |f|=|b|=|D_t|=1/2. The syntax of the Reduce package SsTools, which was used for intermediate computations, and the applicability of its procedures to the calculus of super-PDE are described.
description: MSC 35Q53,37K05,37K10,81T40; PACS 02.30.Ik,02.70.Wz,12.60.Jv; Comput. Phys. Commun. (2007), 26 pages (accepted)
Τεχνικές Ανάλυσης σήματος και μηχανικής μάθησης για τη διάγνωση της Ήπιας Νοητικής Έκπτωσης (MCI) μέσω ηλεκτροεγκεφαλογραφικών αποκρίσεων.
Creators: name: Μπιτζίδου, Μαλαματή Παναγιώτη
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Ήπια νοητική έκπτωση
Μηχανική μάθηση
Σύζευξη φάσης-πλάτους
Mild cognitive impairment
Machine learning
Phase-amplitude coupling

description: Η νόσος Alzheimer αφορά σε υψηλό ποσοστό ανθρώπων μεγάλης ηλικίας, και η αποτελεσματικότερη αντιμετώπισή της προαπαιτεί έγκαιρη διάγνωση, κάτι που δεν είναι ιδιαίτερα εύκολο, διότι οι υπάρχουσες μέθοδοι απαιτούν μεγάλο αριθμό εξετάσεων, αναλύσεων και δοκιμασιών. Σημαντικό μέρος των ερευνητικών προσπαθειών έχει κατευθυνθεί προς τη χρήση ηλεκτροεγκεφαλογραφημάτων γνωσιακών προκλητών δυναμικών (ERPs) ως μέσα διάγνωσης του πρώτου σταδίου της νόσου, το οποίο ονομάζεται ήπια νοητική έκπτωση (Mild Cognitive Impairment - MCI). Προς την κατεύθυνση αυτή, στην παρούσα μελέτη διερευνάται η δυνατότητα χρήσης τεχνικών ψηφιακής επεξεργασίας σήματος, επιλογής χαρακτηριστικών και διάφορων μεθόδων ταξινόμησης με στόχο τη βελτίωση της ακρίβειας των μεθόδων διάγνωσης. Διαπιστώθηκε ότι η ανάλυση χρόνου-συχνοτήτων των καταγραφών και η εύρεση των συσχετίσεων φάσης και πλάτους των σημάτων σε συνδυασμό με την ανάλυση πρωτευουσών συνιστωσών, την επιλογή χαρακτηριστικών και τη χρήση ταξινομητών όπως οι μηχανές εδραίων διανυσμάτων, μπορούν να συμβάλουν σε υψηλά ποσοστά ακρίβειας, όχι μόνο χρησιμοποιώντας ως δεδομένα τα γνωσιακά προκλητά δυναμικά (ERPs), αλλά και τις καταγραφές των προκλητών δυναμικών (EPs).
description: Alzheimer's disease relates to a high percentage of elder people, and effective treatment requires early diagnosis, which is not an easy procedure. The reason is that existing diagnosis methods require a variety of difficult and time consuming examinations and tests. A lot of research effort has been directed toward the use of EEGs of cognitive evoked response potentials (ERPs) as a method of diagnosis of the first stage of the Alzheimer disease, called mild cognitive impairment (MCI). Towards this direction, in this study we investigated the posibility of using digital signal processing techniques, feature extraction methods and classification machines to build a reliable diagnostic tool. It was found that the use of time-frequency analysis and the estimation of phase-amplitude coupling, combined with principal components analysis, feature selection and classifiers such as Support Vector Machines can provide high accuracy, using not only cognitive event related responses (ERPs), but also the no-target evoked potentials (EPs).
Recheneffiziente Trajektorienoptimierung für automatisierte Fahreingriffe
Creators: name: Gutjahr, Benjamin
Publisher: name: KIT Scientific Publishing
Year: 2019
Subjects: Automatisiertes Fahren
Bewegungsplanung
Trajektorienoptimierung
Linear-quadratische Optimierung
Modellprädiktive Regelung
Automated Driving
Motion Planning
Trajectory Optimization
Linear-quadratic Optimization
Model Predictive Control

description: Für das automatisierte Fahren stellt die wirtschaftlich in ein Fahrzeug integrierbare Rechenleistung bei stetig wachsenden Anforderungen für etablierte Methoden der Trajektorienplanung eine große Hürde dar. Durch den konsequenten Einsatz der linear-quadratischen Optimierung werden besonders recheneffiziente Algorithmen zur Bewegungsplanung von Fahrzeugen hergeleitet. Deren praktische Leistungsfähigkeit wird im Realversuch für unterschiedliche Manöver und Dynamikbereiche demonstriert.
Non-axisymmetric instability and fragmentation of general relativistic quasi-toroidal stars
Creators: name: Zink, Burkhard
name: Stergioulas, Nikolaos
name: Hawke, Ian
name: Ott, Christian D.
name: Schnetter, Erik
name: Mueller, Ewald
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: In a recent publication, we have demonstrated that differentially rotating stars admit new channels of black hole formation via fragmentation instabilities. Since a higher order instability of this kind could potentially transform a differentially rotating supermassive star into a multiple black hole system embedded in a massive accretion disk, we investigate the dependence of the instability on parameters of the equilibrium model. We find that many of the models constructed exhibit non-axisymmetric instabilities with corotation points, even for low values of T/|W|, which lead to a fission of the stars into one, two or three fragments, depending on the initial perturbation. At least in the models selected here, an m=1 mode becomes unstable at lower values of T/|W|, which would seem to favor a scenario where one black hole with a massive accretion disk forms. In this case, we have gained evidence that low values of compactness of the initial model can lead to a stabilization of the resulting fragment, thus preventing black hole formation in this scenario.
description: 30 pages, 36 figures. A version with high-resolution color figures can be found at http://www.cct.lsu.edu/~bzink/material/qts_instability.pdf
Line and continuum studies of some star forming regions
Creators: name: Sato, Takashi
Publisher: name: University of British Columbia
Year: 2009

description: Two sets of protostellar objects have been studied using the James Clerk Maxwell Tele- scope as the main observational facility. The first set is a selection of sources from the IRAS Point Source Catalog, originally observed as part of a survey of protostellar candidates. In this present work, the ob- servational database has been extended to include the (sub)millimetre continuum and J = 3 → 2 and 2 → 1lines of CO,¹³C0 and C¹⁷O, and J = 7 → 6 and 5 → 4 lines of CS andC³⁴S. The continuum mapping was able to resolve each source in addition to making flux measurements. The analysis of these flux values using dust emission models is reported in a separate paper. The molecular lines have been analysed using radiative transfer models in the Large Velocity Gradient (LVG) approximation. Molecular hydro- gen densities have been derived for most of the sources studied and have been found to cluster around n ~ 10⁵cm⁻³.No apparent correlations are seen among the observed and derived parameters. NGC 6334 I and NGC 6334 I(North) comprise the second set of objects and are located at the northern end of the molecular cloud complex NGC 6334. This region has been observed using the same lines, and in particular, mapped in CO (J = 3 → 2) and CS (J = 7 →6). “Extreme High Velocity” (ΔV ~ 150 kms⁻¹) wings of CO are seen around NGC 6334 I and the outflow is found to be bipolar. The outfiowing material has been shown using radiative transfer models to contain gas at a density of n ~ 5 x 10³cm⁻³ for a total mass of 2.5Mʘ in the wings. This corresponds to a mass flow rate of 8 x10⁻⁴ Mʘ yr⁻¹ and a mechanical luminosity of 89 Lʘ. A neutral H I wind ejected at high velocity from the star is inferred to be driving this molecular flow. The implied stellar mass loss rate is 4 x 10⁻⁴ Mʘ yr⁻¹. The CO line wings at peak I(North) are much less prominent, with ΔV ~ 20 kms⁻¹, although significant wings are present. They are not, however, in the form of bipolar lobes. Another feature, an extension 30 arcseconds to the northwest of I, has been newly identified. LVG model analysis has been used to derive H₂ densities at a large number of beam positions. This yields n ~ 1.3 x l0⁷cm⁻³ for peak I while for I(North) the gas density is only ~ 4.5 x 10⁵cm⁻³.This contrast in gas density, combined with the lack of a luminous thermonuclear source detected around I, supports the suggestion that NGC 6334 is a very young stellar object but that I(North) is an even younger one. A lower limit of ~ 3000 yr for the age difference between the two systems is inferred from the time scales of the bipolar outflow at NGC 6334 I.
Spin wave dynamics and the determination of intrinsic Gilbert damping in locally-excited Permalloy thin films
Creators: name: Liu, Zhigang
name: Giesen, Fabian
name: Zhu, Xiaobin
name: Sydora, Richard D.
name: Freeman, Mark R.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: Time-resolved scanning Kerr effect microscopy has been used to study magnetization dynamics in Permalloy thin films excited by transient magnetic pulses generated by a micrometer-scale transmission line structure. The results are consistent with magnetostatic spin wave theory and are supported by micromagnetic simulations. Magnetostatic volume and surface spin waves are measured for the same specimen using different bias field orientations and can be accurately calculated by k-space integrations over all excited plane wave components. A single damping constant of Gilbert form is sufficient to describe both scenarios. The nonuniform pulsed field plays a key role in the spin wave dynamics, with its Fourier transform serving as a weighting function for the participating modes. The intrinsic Gilbert damping parameter $α$ is most conveniently measured when the spin waves are effectively stationary.
description: 5 pages, 4 figures, accepted by Phys. Rev. Lett
An adaptive Hessian approximated stochastic gradient MCMC method
Creators: name: Wang, Yating
name: Deng, Wei
name: Lin, Guang
Publisher: name: arXiv
Year: 2020
Subjects: subject: Numerical Analysis (math.NA)
subject: Machine Learning (cs.LG)
subject: Optimization and Control (math.OC)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: Bayesian approaches have been successfully integrated into training deep neural networks. One popular family is stochastic gradient Markov chain Monte Carlo methods (SG-MCMC), which have gained increasing interest due to their scalability to handle large datasets and the ability to avoid overfitting. Although standard SG-MCMC methods have shown great performance in a variety of problems, they may be inefficient when the random variables in the target posterior densities have scale differences or are highly correlated. In this work, we present an adaptive Hessian approximated stochastic gradient MCMC method to incorporate local geometric information while sampling from the posterior. The idea is to apply stochastic approximation to sequentially update a preconditioning matrix at each iteration. The preconditioner possesses second-order information and can guide the random walk of a sampler efficiently. Instead of computing and saving the full Hessian of the log posterior, we use limited memory of the sample and their stochastic gradients to approximate the inverse Hessian-vector multiplication in the updating formula. Moreover, by smoothly optimizing the preconditioning matrix, our proposed algorithm can asymptotically converge to the target distribution with a controllable bias under mild conditions. To reduce the training and testing computational burden, we adopt a magnitude-based weight pruning method to enforce the sparsity of the network. Our method is user-friendly and is scalable to standard SG-MCMC updating rules by implementing an additional preconditioner. The sparse approximation of inverse Hessian alleviates storage and computational complexities for large dimensional models. The bias introduced by stochastic approximation is controllable and can be analyzed theoretically. Numerical experiments are performed on several problems.
Patch2Self: Denoising Diffusion MRI with Self-Supervised Learning
Creators: name: Fadnavis, Shreyas
name: Batson, Joshua
name: Garyfallidis, Eleftherios
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (cs.LG)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Quantitative Methods (q-bio.QM)
subject: FOS: Computer and information sciences
subject: FOS: Biological sciences

description: Diffusion-weighted magnetic resonance imaging (DWI) is the only noninvasive method for quantifying microstructure and reconstructing white-matter pathways in the living human brain. Fluctuations from multiple sources create significant additive noise in DWI data which must be suppressed before subsequent microstructure analysis. We introduce a self-supervised learning method for denoising DWI data, Patch2Self, which uses the entire volume to learn a full-rank locally linear denoiser for that volume. By taking advantage of the oversampled q-space of DWI data, Patch2Self can separate structure from noise without requiring an explicit model for either. We demonstrate the effectiveness of Patch2Self via quantitative and qualitative improvements in microstructure modeling, tracking (via fiber bundle coherency) and model estimation relative to other unsupervised methods on real and simulated data.
Spin-charge gauge approach to metal-insulator crossover and transport properties in High-T$_c$ cuprates
Creators: name: Marchetti, P. A.
name: Su, Z. B.
name: Yu, L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The spin-charge gauge approach to consider the metal-insulator crossover (MIC) and other anomalous transport properties in High-T$_c$ cuprates is briefly reviewed. A U(1) field gauging the global charge symmetry and an SU(2) field gauging the global spin-rotational symmetry are introduced to study the two-dimensional $t-J$ model in the limit $t\gg J$. The MIC as a clue to the understanding of the ``pseudogap'' (PG) phase, is attributed to the competition between the short-range antiferromagnetic order and dissipative motion of charge carriers coupled to the slave-particle gauge field. The composite particle formed by binding the charge carrier (holon) and spin excitation (spinon) via the slave particle gauge field exhibits a number of peculiar properties, and the calculated results are in good agreement with experimental data for both PG and ``strange metal'' phases. Connections to other gauge field approaches in studying the strong correlation problem are also briefly outlined.
description: 32 pages, to appear in the special issue on "Correlated Electrons" of J. Phys.: Condens. Matt