cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Μια αναλυτική προσέγγιση στο πρόβλημα καταστροφής με Ν παίκτες:
Creators: name: Παπατσίρος, Γεράσιμος Γεωργίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2010
Subjects: Καταστροφή παίκτη
Ν παίκτες
Μαρκοβιανές διαδικασίες
Ruin problem
N player
Markov processes

description: Στην παρούσα εργασία θα παρουσιάσουμε μια γενίκευση του προβλήματος που είναι γνωστό ως πρόβλημα καταστροφής παίκτη (The Gambler's Ruin Problem), στo οποίo παίκτες με πεπερασμένο αρχικό κεφάλαιο παίζουν μια ακολουθία από παιχνίδια έως τη χρονική στιγμή που κάποιος παίκτης θα καταστραφεί (που να έχει δηλαδή κεφάλαιο ίσο με μηδέν). Η εργασία πραγματοποιείται κάνοντας χρήση των εφαρμοσμένων πιθανοτήτων, επικεντρώνοντας το ενδιαφέρον στις θεωρητικές πτυχές και τις επιπτώσεις του προβλήματος. Στόχος μας είναι να παρουσιάσουμε ακριβείς και συμπωτικές λύσεις, και γι 'αυτό θα χρησιμοποιήσουμε Μαρκοβιανές διαδικασίες, κίνηση Brown, Αναλυτική Θεωρία Πινάκων (Markov processes, Brownian motions, Matrix-Analytic theory). Οι εφαρμογές και τα αποτελέσματα που παρουσιάζονται στις επόμενες σελίδες έχουν σκοπό να δώσουν ένα συνοπτικό θεωρητικό υπόβαθρο για κάθε ένα από τα μαθηματικά εργαλεία που αναφέρθηκαν προηγουμένως. Αρχικά παρουσιάζονται λύσεις οι οποίες είναι ευρέως γνωστές και οι οποίες προκύπτουν χρησιμοποιώντας martingales. Στην συνέχεια ακολουθεί η γενίκευση του κλασικού προβλήματος καταστροφής για δυο παίκτες. Παρουσιάζεται μια μελέτη αυτού του προβλήματος σε διακριτό χρόνο για έναν αυθαίρετο αριθμό N παικτών, καθώς και μια ασυμπτωτική ανάλυση σε συνεχή χρόνο, που ισχύει όταν το N είναι ίσον ή μικρότερο του 3.
description: This thesis presents a generalization of a problem known as the gambler's ruin problem, in which two players with finite initial capital play a sequence of games until one of them is ruined. This research is therefore carried out under the frame of applied probability, even though our main interest focuses on the theoretical aspects and implications of this problem. Our aim is to illustrate exact and asymptotic solutions, and for this reason we use tools as varied as Markov processes, Brownian motions and Matrix-Analytic theory. The applications and results included in the next few pages give a concise theoretical background to each of the mathematical tools we have applied in our research. Initially, we present solutions that are widely known and obtained using martingales. A generalization of the classical gambler's ruin problem for two players is also provided. Finally, we demonstrate a study of this problem in discrete time for an arbitrary number N of players and an asymptotic resolution in continuous time, which is valid when N is equal or less than 3.
Electron-Stimulated Emission of Na Atoms from NaCl Nanocube Corners
Creators: name: Ceresoli, D.
name: Zykova-Timan, T.
name: Tosatti, E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We performed first principles density functional calculations and simulations of magic-size neutral NaCl nanocubes, and computed the the extraction of a Na neutral corner atom after donating an electron. The atomic structure of the resulting Na corner vacancy is presented.
description: 7 pages, 2 figures, 1 table; to appear on Surf. Sci
Byzantines can also Learn from History: Fall of Centered Clipping in Federated Learning
Creators: name: Ozfatura, Kerem
name: Ozfatura, Emre
name: Kupcu, Alptekin
name: Gunduz, Deniz
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: Cryptography and Security (cs.CR)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: The increasing popularity of the federated learning (FL) framework due to its success in a wide range of collaborative learning tasks also induces certain security concerns. Among many vulnerabilities, the risk of Byzantine attacks is of particular concern, which refers to the possibility of malicious clients participating in the learning process. Hence, a crucial objective in FL is to neutralize the potential impact of Byzantine attacks and to ensure that the final model is trustable. It has been observed that the higher the variance among the clients' models/updates, the more space there is for Byzantine attacks to be hidden. As a consequence, by utilizing momentum, and thus, reducing the variance, it is possible to weaken the strength of known Byzantine attacks. The centered clipping (CC) framework has further shown that the momentum term from the previous iteration, besides reducing the variance, can be used as a reference point to neutralize Byzantine attacks better. In this work, we first expose vulnerabilities of the CC framework, and introduce a novel attack strategy that can circumvent the defences of CC and other robust aggregators and reduce their test accuracy up to %33 on best-case scenarios in image classification tasks. Then, we propose a new robust and fast defence mechanism that is effective against the proposed and other existing Byzantine attacks.
description: IEEE Transactions on Information Forensics and Security 2023
Experimental observation of the intricate free-energy landscape for a soft glassy system
Creators: name: Jabbari-Farouji, Sara
name: Wegdam, Gerard H.
name: Bonn, Daniel
Publisher: name: arXiv
Year: 2006
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: In the free energy landscape picture of glassy systems, the slow dynamics characteristic of these systems is believed to be due to the existence of a complicated free-energy landscape with many local minima. We show here that for a colloidal glassy material multiple paths can be taken through the free energy landscape, that can even lead to different 'final' non-ergodic states at the late stages of aging. We provide clear experimental evidence for the distinction of gel and glassy states in the system and show that for a range of colloid concentrations, the transition to non-ergodicity can occur in either direction (gel or glass), and may be accompanied by 'hesitations' between the two directions. This shows that colloidal gels and glasses are merely global free-energy minima in the same free energy landscape, and that the paths leading to these minima can indeed be complicated.
description: 5 pages, 5 figures
Μορφολογικά και ιζηματολογικά χαρακτηριστικά του δέλτα του Νέστου ποταμού μετά την κατασκευή των φραγμάτων:
Creators: name: Γαρέζος, Αντώνης Βλάσης
Publisher: name: Aristotle University of Thessaloniki
Year: 2010
Subjects: Δέλτα Νέστου
Παράκτια γεωμορφολογία
Παράκτια διάβρωση
Delta of Nestos
Coastal geormophology
Coastal erosion

description: Αντικείμενο της παρούσας διατριβής ειδίκευσης είναι η ιζηματολογική μελέτη στην παράκτια ζώνη του δέλτα του Νέστου και γεωμορφολογική καταγραφή του σύγχρονου-ενεργού δέλτα. Σκοπός της εργασίας ήταν να διερευνήθηκε η επίδραση που προκαλούν τα φράγματα με την μείωση των φερτών υλικών στις γεωμορφολογικές δομές του δέλτα και κατ’ επέκταση κατά πόσο η μείωση αυτή προκαλεί ενδείξεις διάβρωσης στην παράκτια ζώνη. Η εργασία της υπαίθρου χωρίστηκε σε δύο στάδια. Το πρώτο αφορούσε την ιζηματολογική έρευνα και το δεύτερο την χαρτογράφηση μέρους της ακτογραμμής με τη χρήση G.P.S (GMS-2 της εταιρίας Topcon). Ο λόγος των συγκεκριμένων ενεργειών αφορούσε την καταγραφή της μεταφορικής ικανότητας του ποταμού στην εκβολή και την κατανομή του υλικού εκατέρωθεν αυτής σε όλο το μήκος της ακτογραμμής. Από την άλλη, η σύγκριση της ακτογραμμής, μέσω του G.P.S, με αυτή των τοπογραφικών χαρτών αντίστοιχα, αποσκοπούσε στις μεταβολές που παρουσιάζονται πριν και μετά την κατασκευή των φραγμάτων.Τέλος η καταγραφή των παράκτιων γεωμορφών που αφορά την αρίθμηση, ανάλυση και απεικόνιση των δόμων σε όλη την έκταση του παράκτιου Δέλτα, οδήγησε στη δημιουργία ενός γεωμορφολογικού χάρτη της εν λόγω περιοχής μελέτης.
description: Purpose of this study is Sedimentological study of the coastal area of delta of the river Nestos and geomorphological analysis of active delta. The purpose of this study was to investigated the effect of causing dams to reduce sediment in the geological structures of delta and how much this reduction causes signs of erosion in coastal zone.The work of the countryside was divided in two stages. The first part concerned the Sedimentological research and the second the shoreline mapping using Differential Global Positioning System (GMS-2 the company Topcon). The causes of these actions related to the recording ability of the river mouth and sentiment distribution across the coastline. On the other hand, the comparison of the coastline, with GPS compared with coastline of topographic maps, aimed the changes presented after the construction of dams.Finally, the record of coastal landforms, the analysis and visualization of structures through the coastal delta, resulted a geomorphological map of the study area.
Sharp and fuzzy observables on effect algebras
Creators: name: Jencova, A.
name: Pulmannova, S.
name: Vincekova, E.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 81P10, 81P15

description: Observables on effect algebras and their fuzzy versions obtained by means of confidence measures (Markov kernels) are studied. It is shown that, on effect algebras with the (E)-property, given an observable and a confidence measure, there exists a fuzzy version of the observable. Ordering of observables according to their fuzzy properties is introduced, and some minimality conditions with respect to this ordering are found. Applications of some results of classical theory of experiments are considered.
description: 23 pages
An overview of epidemic models with phase transitions to absorbing states running on top of complex networks
Creators: name: Mata, Angélica S.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Dynamical systems running on the top of complex networks has been extensively investigated for decades. But this topic still remains among the most relevant issues in complex network theory due to its range of applicability. The contact process (CP) and the susceptible-infected-susceptible (SIS) model are used quite often to describe epidemic dynamics. Despite their simplicity, these models are robust to predict the kernel of real situations. In this work, we review concisely both processes that are well-known and very applied examples of models that exhibit absorbing-state phase transitions. In the epidemic scenario, individuals can be infected or susceptible. A phase transition between a disease-free (absorbing) state and an active stationary phase (where a fraction of the population is infected) are separated by an epidemic threshold. For the SIS model, the central issue is to determine this epidemic threshold on heterogeneous networks. For the CP model, the main interest is to relate critical exponents with statistical properties of the network.
The roles of GIS in planning : a critical appraisal of the technology for urban and regional planning
Creators: name: Xu, Haizi
Publisher: name: University of British Columbia
Year: 2009

description: The proliferation of Geographic Information Systems (GISs) in the planning profession has been phenomenal in recent years. However, it is not clear what roles GIS can play in the today's planning context. This thesis sets out to explore this topic through the investigation of the nature of planning, the history of computer application in planning, the GIS technology itself, and half a dozen real-life GIS applications. On the "demand" side, the literature review shows that today's planning is highly political in nature, with technical concerns having receded to a secondary place of importance. As a result, the use of information in the profession is very much communicative, shifting the emphasis from the analytical use of information to a more presentational use of information. While on the "supply" side, the study of the technology itself reveals that GIS is a hybrid technology that is the marriage of electronic mapping, database technology, and computer modeling. It has the technological potential to be customized to serve different ends in planning. There is an apparently good match between planning's use of information and GIS's functionality, suggesting that there is considerable potential in the application of the technology to the profession. Unfortunately, the current theory about GIS application in planning focuses rather narrowly on the technical use of the technology and turns a blind eye on the technology's capability to aid communicative planning. This thesis points out that the current theory on GIS's application in planning is inadequate for the profession to take full advantage of the technology. It concludes that GIS can serve all three major information processing functions: information presentation, information management, and information analysis, and recommends more presentationoriented use of the technology in planning.
Can four-zero-texture mass matrix model reproduce the observed quark and lepton mixing angles and CP violating phases?
Creators: name: Matsuda, Koichi
name: Nishiura, Hiroyuki
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We reconsider an universal mass matrix model which has a seesaw-invariant structure with four-zero texture common to all quarks and leptons. The CKM quark and MNS lepton mixing matrices of the model are analyzed analytically.We show that the model can be consistent with all the experimental data of neutrino oscillation and quark mixings by tuning free parameters of the model. It is also shown that the model predicts a relatively large value for (1,3) element of the MNS lepton mixing matrix, |(U_{MNS})_{13}|^2 \simeq 2.6 \times 10^{-2}. Using the seesaw mechanism, we also discuss the conditions for the components of the Dirac and the right-handed Majorana neutrino mass matrices which lead to the neutrino mass matrix consistent with the experimental data.
description: 21 pages, 3 figures
Ludopédagogie : le jeu au service des apprentissages
Creators: name: Latour, Marie
Publisher: name: Zenodo
Year: 2023
Subjects: gamification
ludification
ludicisation
bibliothèque
library

description: Ce support de présentation, utilisée lors de la Journée d'étude "La ludopédagogie - Le jeu au service des apprentissages" qui a eu lieu le 6 avril 2023 à l'Université d'Artois, a pour objectifs d'expliquer ce que recouvrent les pédagogies par le jeu et comment les mettre en place au sein d'une structure.

Contact : marie.latour@unc.nc
Direct manipulation of a superconducting spin qubit strongly coupled to a transmon qubit
Creators: name: Pita-Vidal, Marta
name: Bargerbos, Arno
name: Žitko, Rok
name: Splitthoff, Lukas J.
name: Grünhaupt, Lukas
name: Wesdorp, Jaap J.
name: Liu, Yu
name: Kouwenhoven, Leo P.
name: Aguado, Ramón
name: van Heck, Bernard
name: Kou, Angela
name: Andersen, Christian Kraglund
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Spin qubits in semiconductors are currently one of the most promising architectures for quantum computing. However, they face challenges in realizing multi-qubit interactions over extended distances. Superconducting spin qubits provide a promising alternative by encoding a qubit in the spin degree of freedom of an Andreev level. Such an Andreev spin qubit could leverage the advantages of circuit quantum electrodynamic, enabled by an intrinsic spin-supercurrent coupling. The first realization of an Andreev spin qubit encoded the qubit in the excited states of a semiconducting weak-link, leading to frequent decay out of the computational subspace. Additionally, rapid qubit manipulation was hindered by the need for indirect Raman transitions. Here, we exploit a different qubit subspace, using the spin-split doublet ground state of an electrostatically-defined quantum dot Josephson junction with large charging energy. Additionally, we use a magnetic field to enable direct spin manipulation over a frequency range of 10 GHz. Using an all-electric microwave drive we achieve Rabi frequencies exceeding 200 MHz. We furthermore embed the Andreev spin qubit in a superconducting transmon qubit, demonstrating strong coherent qubit-qubit coupling. These results are a crucial step towards a hybrid architecture that combines the beneficial aspects of both superconducting and semiconductor qubits.
Eigen modes for the problem of anomalous light transmission through subwavelength holes
Creators: name: Sturman, B.
name: Podivilov, E.
name: Gorkunov, M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We show that the wide-spread concept of optical eigen modes in lossless waveguide structures, which assumes the separation on propagating and evanescent modes, fails in the case of metal-dielectric structures, including photonic crystals. In addition to these modes, there is a sequence of new eigen-states with complex values of the propagation constant and non-vanishing circulating energy flow. The whole eigen-problem ceases to be hermitian because of changing sign of the optical dielectric constant. The new anomalous modes are shown to be of prime importance for the description of the anomalous light transmission through subwavelength holes.
description: 5 pages, 4 figures
A transition from river networks to scale-free networks
Creators: name: Nandi, A. K.
name: Manna, S. S.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A spatial network is constructed on a two dimensional space where the nodes are geometrical points located at randomly distributed positions which are labeled sequentially in increasing order of one of their co-ordinates. Starting with $N$ such points the network is grown by including them one by one according to the serial number into the growing network. The $t$-th point is attached to the $i$-th node of the network using the probability: $π_i(t) \sim k_i(t)\ell_{ti}^α$ where $k_i(t)$ is the degree of the $i$-th node and $\ell_{ti}$ is the Euclidean distance between the points $t$ and $i$. Here $α$ is a continuously tunable parameter and while for $α=0$ one gets the simple Barabási-Albert network, the case for $α\to -\infty$ corresponds to the spatially continuous version of the well known Scheidegger's river network problem. The modulating parameter $α$ is tuned to study the transition between the two different critical behaviors at a specific value $α_c$ which we numerically estimate to be -2.
description: 5 pages, 5 figure
Τα κριτήρια επιμέτρησης και η επιμέτρηση της χρηματικής ικανοποίησης λόγω ηθικής βλάβης ή ψυχικής οδύνης από τροχαία ατυχήματα.:
Creators: name: Ακριτίδου, Αλεξία Μιχαήλ
Publisher: name: Aristotle University of Thessaloniki
Year: 2010
Subjects: Ηθική βλάβη
Ψυχική οδύνη
Κριτήρια επιμέτρησης
Τροχαία ατυχήματα
Non pecuniary loss
Admeasurement criteria
Road accident

description: Στόχος της εργασίας είναι να εκτεθεί το εγχώριο σύστημα επιμέτρησης της χρηματικής ικανοποίησης λόγω ηθικής βλάβης και ψυχικής οδύνης με έμφαση στα κριτήρια επιμέτρησης στον τομέα των τροχαίων ατυχημάτων καθώς και να διερευνηθούν τα τρωτά του συστήματος αυτού. Η ακολουθούμενη δομή είναι η εξής: Στο πρώτο μέρος θα θιγούν γενικά ζητήματα ηθικής βλάβης αυστηρά σχετικά με το κύριο θέμα της εργασίας. Στο δεύτερο θα αναλυθούν τα επιμέρους κριτήρια επιμέτρησης και θα διερευνηθεί ο τρόπος εφαρμογής των κριτηρίων αυτών, όπως προκύπτει από την ανάλυση ικανού δείγματος αποφάσεων της τελευταίας εικοσαετίας. Στο τρίτο μέρος θα θεωρηθεί η επιμέτρηση και το αποτέλεσμά της σε συνάρτηση με την αρχή της αναλογικότητας.
description: The main objective of this project is to present the Greek system of damages for non pecuniary loss emphasizing on the admeasurement criteria in the section of road accidents and to investigate the weaknesses of this system.The structure of the project is as follows: In the first part, there will be brought forward general matters, strictly related with the main subject of this project. In the second part, there will be analysed the individual admeasurement criteria and there will be investigated the manner of how to apply these criteria, as a result of the analysis of a considerable court-rules from the last 20 years. In the third part, the admeasurement and the results of it will be considered involving the principle of proportionality.
X-ray Flux and Spectral Variability of the TeV Blazars Mrk 421 and PKS 2155-304
Creators: name: Gupta, Alok C.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We reviewed X-ray flux and spectral variability properties studied to date by various X-ray satellites for Mrk 421 and PKS 2155-304, which are TeV emitting blazars. Mrk 421 and PKS 2155-304 are the most X-ray luminous blazars in the northern and southern hemispheres, respectively. Blazars show flux and spectral variabilities in the complete electromagnetic spectrum on diverse timescales ranging from a few minutes to hours, days, weeks, months and even several years. The flux and spectral variability on different timescales can be used to constrain the size of the emitting region, estimate the super massive black hole mass, find the dominant emission mechanism in the close vicinity of the super massive black hole, search for quasi-periodic oscillations in time series data and~several other physical parameters of blazars. Flux and spectral variability is also a dominant tool to explain jet as well as disk emission from blazars at different epochs of observations.
description: 15 pages, Published in the special issue "X-Ray Flux and Spectral Variability of Blazars" of Galaxies Journal
Painleve versus Fuchs
Creators: name: Boukraa, S.
name: Hassani, S.
name: Maillard, J. -M.
name: McCoy, B. M.
name: Weil, J. -A.
name: Zenine, N.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mathematical Physics (math-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences
subject: 33E17, 33E05, 33Cxx, 33Dxx, 14Exx, 14Hxx, 34M55, 47E05, 34Lxx, 34Mxx, 14Kxx

description: The sigma form of the Painlev{é} VI equation contains four arbitrary parameters and generically the solutions can be said to be genuinely ``nonlinear'' because they do not satisfy linear differential equations of finite order. However, when there are certain restrictions on the four parameters there exist one parameter families of solutions which do satisfy (Fuchsian) differential equations of finite order. We here study this phenomena of Fuchsian solutions to the Painlev{é} equation with a focus on the particular PVI equation which is satisfied by the diagonal correlation function C(N,N) of the Ising model. We obtain Fuchsian equations of order $N+1$ for C(N,N) and show that the equation for C(N,N) is equivalent to the $N^{th}$ symmetric power of the equation for the elliptic integral $E$. We show that these Fuchsian equations correspond to rational algebraic curves with an additional Riccati structure and we show that the Malmquist Hamiltonian $p,q$ variables are rational functions in complete elliptic integrals. Fuchsian equations for off diagonal correlations $C(N,M)$ are given which extend our considerations to discrete generalizations of Painlev{é}.
description: 18 pages, Dedicated to the centenary of the publication of the Painleve VI equation in the Comptes Rendus de l'Academie des Sciences de Paris by Richard Fuchs in 1905
Noise spectrum of a tunnel junction coupled to a nanomechanical oscillator
Creators: name: Wabnig, J.
name: Rammer, J.
name: Shelankov, A. L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: A nanomechanical resonator coupled to a tunnel junction is studied. The oscillator modulates the transmission of the junction, changing the current and the noise spectrum. The influence of the oscillator on the noise spectrum of the junction is investigated, and the noise spectrum is obtained for arbitrary frequencies, temperatures and bias voltages. We find that the noise spectrum consists of a noise floor and a peaked structure with peaks at zero frequency, the oscillator frequency and twice the oscillator frequency. The influence of the oscillator vanishes if the bias voltage of the junction is lower than the oscillator frequency. We demonstrate that the peak at the oscillator frequency can be used to determine the oscillator occupation number, showing that the current noise in the junction functions as a thermometer for the oscillator.
description: 33 pages, 7 figures, references adjusted
Diffraction 2006: Theoretical Summary
Creators: name: Forshaw, Jeffrey R.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: This paper presents a summary of the theoretical presentations to the international workshop "Diffraction 2006". The range of topics covered during the workshop was quite broad and this summary is therefore somewhat selective covering recent developments in BFKL physics, exclusive processes, saturation dynamics, DIS and structure functions and coherence in QCD.
description: 16 pages. Talk presented at "Diffraction 2006"
Διαχείριση και σύνθεση χαρτοφυλακίου:
Creators: name: Αρχοντάκη, Κωνσταντίνα Αθανασίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2010
Subjects: Διαχείριση Χαρτοφυλακίου
Πολυκριτηριακές Μέθοδοι
Βελτιστοποίηση Χαρτοφυλακίου
Portfolio Management
Multicriteria Methods
Portfolio Optimization

description: Η επιλογή του κατάλληλου χαρτοφυλακίου είναι ένα πρόβλημα που απασχολεί την χρηματοοικονομική επιστήμη από την αρχή. Τα τελευταία χρόνια υπήρξε η ανάδυση των κεφαλαιαγορών, η ραγδαία βελτίωση των τεχνολογικών επιστημών και τελικά οι παράγοντες που ακούν στους όρους «ελεύθερη αγορά» και «μόχλευση». Με την ανάπτυξη της πληροφορικής και συγκεκριμένα των πολυκριτηριακών μεθόδων λήψης αποφάσεων, υπάρχει η δυνατότητα να ελέγξουμε πολύπλοκα μαθηματικά μοντέλα για την επιλογή του καλύτερου δυνατού χαρτοφυλακίου, δηλαδή αυτού που θα μας αποδίδει την μεγαλύτερη απόδοση με τον μικρότερο δυνατό κίνδυνο. Πάνω σε αυτό το πρόβλημα έχουν αναπτυχθεί πολλές θεωρίες όπως το CAPM, APT, Behavioral και πολλές τεχνικές αναλύσεις. Στην παρούσα εργασία παρουσιάζεται μια πολυδιάστατη μεθοδολογία που βασίζεται στην χρηματοοικονομική ανάλυση των εταιρειών. Προτείνεται μία μέθοδος τριών σταδίων: στο πρώτο στάδιο αξιολογούνται αριθμοδείκτες όπως απόδοσης, ρευστότητας, βιωσιμότητας και επένδυσης με την χρήση της μεθόδου ELECTRE-Tri για να επιλεγούν οι μετοχές που θα απαρτίζουν το χαρτοφυλάκιο. Στο δεύτερο στάδιο εφαρμόζεται η μέθοδος της βελτιστοποίησης χαρτοφυλακίου του Markowitz προκειμένου να καθοριστεί το μέγεθος της συμμετοχής κάθε μετοχής στο χαρτοφυλάκιο. Τέλος με την μέθοδο ELECTRE III γίνεται αξιολόγηση των χαρτοφυλακίων που προκύπτουν και παρουσιάζεται το χαρτοφυλάκιο με την υψηλότερη κατάταξη.
description: The selection of the optimal portfolio is a problem that concerns the financial science since many years. Nowadays, due to the development of information technology and specifically of multicriteria decision making methods, we are able to control complex mathematical models and to select the optimal portfolio that provides the highest return with less risk. Based on this, many theories such as CAPM, APT, Behavioral and many techniques of technical analysis have been developed. This paper presents a multidimensional methodology based on the financial analysis of companies. A method is proposed in three stages: in the first stage financial ratios such as performance, liquidity, sustainability and investment are being evaluated, using the method ELECTRE-Tri to select the stocks of the portfolio. In the second stage the Markowitz portfolio optimization method is applied in order to determine the extent of participation of each stock in the portfolio. Finally, with the use of ELECTRE III method we evaluate the portfolios and present the portfolio with the highest rating.
Relativistic Green functions in a plane wave gravitational background
Creators: name: Vaidya, A. N.
name: Farina, C.
name: Guimaraes, M. S.
name: Neves, M. J.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider a massive relativistic particle in the background of a gravitational plane wave. The corresponding Green functions for both spinless and spin 1/2 cases, previously computed by A. Barducci and R. Giachetti \cite{Barducci3}, are reobtained here by alternative methods, as for example, the Fock-Schwinger proper-time method and the algebraic method. In analogy to the electromagnetic case, we show that for a gravitational plane wave background a semiclassical approach is also sufficient to provide the exact result, though the lagrangian involved is far from being a quadratic one.
description: Last paper by Professor Arvind Narayan Vaidya, 18 pages, no figures
Well-posedness of the three-dimensional NLS equation with sphere-concentrated nonlinearity
Creators: name: Finco, Domenico
name: Tentarelli, Lorenzo
name: Teta, Alessandro
Publisher: name: arXiv
Year: 2022
Subjects: subject: Analysis of PDEs (math.AP)
subject: Mathematical Physics (math-ph)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 81Q35, 35Q40, 35Q55, 35R06, 33C55, 33C10, 33C45, 44A15, 47A60

description: We discuss strong local and global well-posedness for the three-dimensional NLS equation with nonlinearity concentrated on $\mathbb{S}^2$. Precisely, local well-posedness is proved for any $C^2$ power-nonlinearity, while global well-posedness is obtained either for small data or in the defocusing case under some growth assumptions. With respect to point-concentrated NLS models, widely studied in the literature, here the dimension of the support of the nonlinearity does not allow a direct extension of the known techniques and calls for new ideas.
description: 40 pages. Keywords: NLS equation, concentrated nonlinearity, unit sphere, well-posedness, spherical harmonics. Minor changes have been made with respect to the previous version
Joint Model for Survival and Multivariate Sparse Functional Data with Application to a Study of Alzheimer's Disease
Creators: name: Li, Cai
name: Xiao, Luo
name: Luo, Sheng
Publisher: name: arXiv
Year: 2020
Subjects: subject: Methodology (stat.ME)
subject: Applications (stat.AP)
subject: Computation (stat.CO)
subject: FOS: Computer and information sciences

description: Studies of Alzheimer's disease (AD) often collect multiple longitudinal clinical outcomes, which are correlated and predictive of AD progression. It is of great scientific interest to investigate the association between the outcomes and time to AD onset. We model the multiple longitudinal outcomes as multivariate sparse functional data and propose a functional joint model linking multivariate functional data to event time data. In particular, we propose a multivariate functional mixed model (MFMM) to identify the shared progression pattern and outcome-specific progression patterns of the outcomes, which enables more interpretable modeling of associations between outcomes and AD onset. The proposed method is applied to the Alzheimer's Disease Neuroimaging Initiative study (ADNI) and the functional joint model sheds new light on inference of five longitudinal outcomes and their associations with AD onset. Simulation studies also confirm the validity of the proposed model.
Modelling and classifying joint trajectories of self-reported mood and pain in a large cohort study
Creators: name: Das, Rajenki
name: Muldoon, Mark
name: Lunt, Mark
name: McBeth, John
name: Yimer, Belay Birlie
name: House, Thomas
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: It is well-known that mood and pain interact with each other, however individual-level variability in this relationship has been less well quantified than overall associations between low mood and pain. Here, we leverage the possibilities presented by mobile health data, in particular the "Cloudy with a Chance of Pain" study, which collected longitudinal data from the residents of the UK with chronic pain conditions. Participants used an App to record self-reported measures of factors including mood, pain and sleep quality. The richness of these data allows us to perform model-based clustering of the data as a mixture of Markov processes. Through this analysis we discover four endotypes with distinct patterns of co-evolution of mood and pain over time. The differences between endotypes are sufficiently large to play a role in clinical hypothesis generation for personalised treatments of comorbid pain and low mood.
Quantized Variational Inference
Creators: name: Dib, Amir
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: We present Quantized Variational Inference, a new algorithm for Evidence Lower Bound maximization. We show how Optimal Voronoi Tesselation produces variance free gradients for ELBO optimization at the cost of introducing asymptotically decaying bias. Subsequently, we propose a Richardson extrapolation type method to improve the asymptotic bound. We show that using the Quantized Variational Inference framework leads to fast convergence for both score function and the reparametrized gradient estimator at a comparable computational cost. Finally, we propose several experiments to assess the performance of our method and its limitations.
$Z_3$ and $(\times Z_3)^3$ symmetry protected topological paramagnets
Creators: name: Topchyan, Hrant
name: Iugov, Vasilii
name: Mirumyan, Mkhitar
name: Khachatryan, Shahane A.
name: Hakobyan, Tigran S.
name: Sedrakyan, Tigran A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We identify two-dimensional three-state Potts paramagnets with gapless edge modes on a triangular lattice protected by $(\times Z_3)^3\equiv Z_3\times Z_3\times Z_3$ symmetry and smaller $Z_3$ symmetry. We derive microscopic models for the gapless edge, uncover their symmetries, and analyze the conformal properties. We study the properties of the gapless edge by employing the numerical density-matrix renormalization group (DMRG) simulation and exact diagonalization. We discuss the corresponding conformal field theory, its central charge, and the scaling dimension of the corresponding primary field. We argue that the low energy limit of our edge modes is defined by the $SU_k(3)/SU_k(2)$ coset conformal field theory with the level $k=2$. The discussed two-dimensional models realize a variety of symmetry-protected topological phases, opening a window for studies of the unconventional quantum criticalities between them.
description: 37 pages, 11 figures
Development of a Practicable Digital Pulse Read-out for Dark-field STEM
Creators: name: Mullarkey, Tiarnan
name: Downing, Clive
name: Jones, Lewys
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: When characterising beam-sensitive materials in the scanning transmission electron microscope (STEM), low-dose techniques are essential for the reliable observation of samples in their true state. A simple route to minimise both the total electron-dose and the dose-rate is to reduce the electron beam-current and/or raster the probe at higher speeds. At the limit of these settings, and with current detectors, the resulting images suffer from unacceptable artefacts including; signal-streaking, detector-afterglow, and poor signal-to-noise ratios (SNR). In this manuscript we present an alternative approach to capture dark-field STEM images by pulse-counting individual electrons as they are scattered to the annular dark-field (ADF) detector. Digital images formed in this way are immune from analogue artefacts of streaking or afterglow and allow clean, high-SNR images to be obtained even at low beam-currents. We present results from both a ThermoFisher FEI Titan G2 operated at 300kV and a Nion UltraSTEM200 operated at 200kV, and compare the images to conventional analogue recordings. ADF data are compared with analogue counterparts for each instrument, a digital detector-response scan is performed on the Titan, and the overall rastering efficiency is evaluated for various scanning parameters.
Αυτόματη παραγωγή περιπτώσεων ελέγχου με χρήση μεθοδολογίας αυτόματου ελέγχου μοντέλων:
Creators: name: Αλμαλιώτης, Βασίλειος Χρήστου
Publisher: name: Aristotle University of Thessaloniki
Year: 2010
Subjects: Περιπτώσεις ελέγχου
Αντόματος έλεγχος μοντέλων
Ελεγχος λευκού κουτιού
Test cases
Model checking
White box testing

description: Αυτή η μεταπτυχιακή διπλωματική εργασία, παρουσιάζει μια μέθοδο για την αυτοματοποίηση της διαδικασίας εξαγωγής περιπτώσεων ελέγχου, με την χρήση του αυτόματου ελέγχου μοντέλων. Η κυρίως προσπάθεια, εστιάζει τόσο στην αυτοματοποιημένη και σωστή εξαγωγή του μοντέλου του λογισμικού υπό εξέταση από τον πηγαίο κώδικα, όσο και στην διευκόλυνση της κατασκευής τύπων LTL, με την εύκολη αναγνώριση των εναλλακτικών μονοπατιών που υπάρχου μέσα στο μοντέλο. Σκοπός αυτής της εργασίας είναι η ανάπτυξη μιας μεθοδολογίας, η οποία θα είναι εύκολα υλοποιήσιμη σε έναν ειδικό αναλυτή, που θα παράγει ευέλικτα μοντέλα ειδικά για εξαγωγή περιπτώσεων ελέγχου. Επιπλέον με το πέρας της διαδικασίας, θα παρέχονται σημαντικές πληροφορίες, μέσω του μοντέλου, ώστε ο υπεύθυνος αναλυτής να είναι σε θέση να λαμβάνει εύκολα και αυτόματα απλούς τύπους LTL, ώστε να επιστρέφονται οι μεταβλητές εισόδου, για το μονοπάτι που επέλεξε.
description: This thesis presents a method for the automation of test cases construction process, with usage of model checking. The main effort focuses both on the automated and correct export of the software model from the source code and the convenience on identifying the alternative paths on model and express them with LTL formulas. The aim of this research is to develop a method which can easily implemented in a program parser to create flexible models specific for test cases generation purposes. In addition we provide a framework in which a software engineer can produce simple and automatically LTL formulas, in order to obtain automatically the input variables for a specific path coverage.
Subarcsecond Submillimeter Imaging of the Ultracompact HII Region G5.89-0.39
Creators: name: Hunter, T. R.
name: Brogan, C. L.
name: Indebetouw, R.
name: Cyganowski, C. J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the first subarcsecond submillimeter images of the enigmatic ultracompact HII region (UCHII) G5.89-0.39. Observed with the SMA, the 875 micron continuum emission exhibits a shell-like morphology similar to longer wavelengths. By using images with comparable angular resolution at five frequencies obtained from the VLA archive and CARMA, we have removed the free-free component from the 875 micron image. We find five sources of dust emission: two compact warm objects (SMA1 and SMA2) along the periphery of the shell, and three additional regions further out. There is no dust emission inside the shell, supporting the picture of a dust-free cavity surrounded by high density gas. At subarcsecond resolution, most of the molecular gas tracers encircle the UCHII region and appear to constrain its expansion. We also find G5.89-0.39 to be almost completely lacking in organic molecular line emission. The dust cores SMA1 and SMA2 exhibit compact spatial peaks in optically-thin gas tracers (e.g. 34SO2), while SMA1 also coincides with 11.9 micron emission. In CO(3-2), we find a high-velocity north/south bipolar outflow centered on SMA1, aligned with infrared H2 knots, and responsible for much of the maser activity. We conclude that SMA1 is an embedded intermediate mass protostar with an estimated luminosity of 3000 Lsun and a circumstellar mass of ~1 Msun. Finally, we have discovered an NH3 (3,3) maser 12 arcsec northwest of the UCHII region, coincident with a 44 GHz CH3OH maser, and possibly associated with the Br gamma outflow source identified by Puga et al. (2006).
description: 41 pages, 11 figures, published in The Astrophysical Journal (2008) Volume 680, Issue 2, pp. 1271-1288. An error in the registration of the marker positions in Figure 11 has been corrected in this version
The role of the coroner in the detection of child abuse and neglect
Creators: name: Mero, Alana Elizabeth
Publisher: name: University of British Columbia
Year: 2009

description: The role of the Coroner in child protection is examined from the creation of the office in Medieval England to the current B.C. Coroners Service. Legislation and policy of the Coroner and Ministry of Social Services are examined with regards to investigating deaths of children. An exploratory, descriptive review was conducted of the B.C. Coroner's files for 1986 to 1989 to identify abuse and neglect deaths. Thirtyfive child abuse and neglect deaths were identified. Ministry of Social Services files were searched to determine if there were prior child welfare investigations. Results indicated these had been conducted in 14 of the cases. Five children had been apprehended and returned prior to the incident causing death. Victims and perpetrators were similar to those of other studies. Children under the age of 5 account for 80% of the victims, slightly more males than females were killed, and parent or parent substitutes were identified as the perpetrator in 74% of the deaths. Training for Coroners, social workers, police and medical staff dealing with possible child abuse and neglect deaths is recommended. It is recommended that the Coroner review all deaths in which M.S.S. had, or should have had, any involvement. The Coroner has and continues to play a valuable role in detecting child abuse and neglect, and in educating agencies and the public.
Milnor operations and classifying spaces
Creators: name: Kameko, Masaki
Publisher: name: arXiv
Year: 2022
Subjects: subject: Algebraic Topology (math.AT)
subject: FOS: Mathematics
subject: 55R40

description: We give an example of a nonzero odd degree element of the classifying space of a connected Lie group such that all higher Milnor operations vanish on it. It is a counterexample for a conjecture of Kono and Yagita.
description: 11 pages, accepted for publication in the Proceedings of the American Mathematical Society
Μελέτη της επίδρασης της επιφανειακής τραχύτητας στις οπτικές ιδιότητες των υλικών με τη χρήση της φασματοσκοπικής
Creators: name: Πέτκου, Ιωάννα Γρηγορίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2010
Subjects: Τραχύτητα
Οπτικές ιδιότητες
Φασματοσκοπική ελλειψομετρία
Roughness
Optical properties
Spectroscopic ellipsometry

description: Στα πλαίσια της παρούσης εργασίας μελετήθηκε η επίδραση που έχει η επιφανειακή τραχύτητα στις ελλειψομετρικές ιδιότητες των λεπτών υμενίων. Συγκεκριμένα είδαμε σε θεωρητικό επίπεδο πως επηρεάζει η επιφανειακή τραχύτητα (roughness) τον υπολογισμό των ελλειψομετρικών ποσοτήτων, με ποιες προϋποθέσεις και πως μετατρέπονται οι αντίστοιχοι μαθηματικοί τύποι. Στην συνέχεια αναφερθήκαμε στην θεωρία των Ohlidal και Franta δημιουργήσαμε το κατάλληλο υπολογιστικό πρόγραμμα των ελλειψομετρικών ποσοτήτων σε περιβάλλον Fortran και το εφαρμόσαμε στην περίπτωση του φάσματος του c-Si για να δούμε τις αλλαγές που θα προκύψουν στο φάσμα και που οφείλονται αυτές. Επίσης θα κάνουμε σύγκριση αυτής της θεωρίας με αυτή των Bedeaux και Vleiger και θα δούμε τι διαφορές υπάρχουν μεταξύ τους. Τέλος αναφέραμε τα συμπεράσματα που προκύπτουν από την παραπάνω εργασία και τα μελλοντικά βήματα που μπορούν να γίνουν προς αυτή την κατεύθυνση
description: The aim of the present study is to calculate the effect of surface roughness to the optical constants of the materials via ellipsometry. In fact we saw from the theory how surface roughness effects the ellipsometrical constants, by which conditions, and how the mathematical equations are transformed. Particularly, we refer Ohlidal Franta’s theory and we create the corresponding computational program in FORTRAN environment and then we applied it in the case of c-Si. From this part we saw the differences between the two spectras. Also we compare our results with those from Bedeaux and Vleiger’s theory and saw the differences. At the end we refer the conclusions from this work and the future steps in this direction.
Physics and Nanofriction of Alkali Halide Solid Surfaces at the Melting Point
Creators: name: Zykova-Timan, T.
name: Ceresoli, D.
name: Tartaglino, U.
name: Tosatti, E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: Alkali halide (100) surfaces are anomalously poorly wetted by their own melt at the triple point. We carried out simulations for NaCl(100) within a simple (BMHFT) model potential. Calculations of the solid-vapor, solid-liquid and liquid-vapor free energies showed that solid NaCl(100) is a nonmelting surface, and that the incomplete wetting can be traced to the conspiracy of three factors: surface anharmonicities stabilizing the solid surface; a large density jump causing bad liquid-solid adhesion; incipient NaCl molecular correlations destabilizing the liquid surface, reducing in particular its entropy much below that of solid NaCl(100). Presently, we are making use of the nonmelting properties of this surface to conduct case study simulations of hard tips sliding on a hot stable crystal surface. Preliminary results reveal novel phenomena whose applicability is likely of greater generality.
description: 7 pages, 6 figure; minor typo corrections; to appear in: Surf. Sci