cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Stochastic Gravity: Theory and Applications
Creators: name: Hu, B. L.
name: Verdaguer, E.
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Whereas semiclassical gravity is based on the semiclassical Einstein equation with sources given by the expectation value of the stress-energy tensor of quantum fields, stochastic semiclassical gravity is based on the Einstein-Langevin equation, which has in addition sources due to the noise kernel. In the first part, we describe the fundamentals of this new theory via two approaches: the axiomatic and the functional. In the second part, we describe three applications of stochastic gravity theory. First, we consider metric perturbations in a Minkowski spacetime, compute the two-point correlation functions of these perturbations and prove that Minkowski spacetime is a stable solution of semiclassical gravity. Second, we discuss structure formation from the stochastic gravity viewpoint. Third, we discuss the backreaction of Hawking radiation in the gravitational background of a black hole and describe the metric fluctuations near the event horizon of an evaporating black hole
description: 100 pages, no figures; an update of the 2003 review in Living Reviews in Relativity gr-qc/0307032 ; it includes new sections on the Validity of Semiclassical Gravity, the Stability of Minkowski Spacetime, and the Metric Fluctuations of an Evaporating Black Hole
Efficient Training Data Generation for Phase-Based DOA Estimation
Creators: name: Hübner, Fabian
name: Mack, Wolfgang
name: Habets, Emanuël A. P.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Audio and Speech Processing (eess.AS)
subject: Machine Learning (cs.LG)
subject: Sound (cs.SD)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: Deep learning (DL) based direction of arrival (DOA) estimation is an active research topic and currently represents the state-of-the-art. Usually, DL-based DOA estimators are trained with recorded data or computationally expensive generated data. Both data types require significant storage and excessive time to, respectively, record or generate. We propose a low complexity online data generation method to train DL models with a phase-based feature input. The data generation method models the phases of the microphone signals in the frequency domain by employing a deterministic model for the direct path and a statistical model for the late reverberation of the room transfer function. By an evaluation using data from measured room impulse responses, we demonstrate that a model trained with the proposed training data generation method performs comparably to models trained with data generated based on the source-image method.
description: Submitted to ICASSP 2021
BrCris: Facilitando o Acesso e Integração de Dados para a Comunidade Científica
Creators: name: Garcia de Souza, Marcel
name: Magela Rodrigues Dias, Thiago
name: Segundo, Washington
Publisher: name: Zenodo
Year: 2024

description: Apresentação realizada na sessão Demos, da 15ª Conferência Lusófona de Ciência Aberta, na Escola Superior de Enfermagem do Porto (ESEP), de 01 a 04 de outubro de 2024.
Electronic structure and magnetism in the frustrated antiferromagnet LiCrO2
Creators: name: Mazin, I. I.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: LiCrO2 is a 2D triangular antiferromagnet, isostructural with the common battery material LiCoO2 and a well-known Jahn-Teller antiferromagnet NaNiO2. As opposed to the latter, LiCrO2 exibits antiferromagnetic exchange in Cr planes, which has been ascribed to direct Cr-Cr d-d overlap. Using LDA and LDA+U first principles calculations I confirm this conjecture and show that (a) direct d-d overlap is indeed enhanced compared to isostructural Ni and Cr compounds, (b) p-d charge transfer gap is also enhanced, thus suppressing the ferromagnetic superexchange, (c) the calculated magnetic Hamiltonian maps well onto the nearest neighbors Heisenberg exchange model and (d) interplanar inteaction is antiferromagnetic.
description: 5 pages, 4 figures
MPEC 2024-A16 : 2024 AD
Creators: name: Minor Planet Center Staff
Publisher: name: The Minor Planet Center
Year: 2024
Subjects: subject: Small Solar System bodies
valueUri: http://astrothesaurus.org/uat/1469
subject: 2024 AD

description: The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements.  They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Reconsidering the relation between "matter wave interference" and "wave-particle duality"
Creators: name: Mairhofer, Lukas
name: Passon, Oliver
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: History and Philosophy of Physics (physics.hist-ph)
subject: FOS: Physical sciences

description: Interference of more and more massive objects provides a spectacular confirmation of quantum theory. It is usually regarded as support for "wave-particle duality" and in an extension of this duality even as support for "complementarity". We first give an outline of the historical development of these notions. Already here it becomes evident that they are hard to define rigorously, i.e. have mainly a heuristic function. Then we discuss recent interference experiments of large and complex molecules which seem to support this heuristic function of "duality". However, we show that in these experiments the diffraction of a {\em delocalized} center-of-mass wave function depends on the interaction of the {\em localized} structure of the molecule with the diffraction element. Thus, the molecules display "dual features" at the same time, which contradicts the usual understanding of wave-particle duality. We conclude that the notion of "wave-particle duality" deserves no place in modern quantum physics.
description: 15 pages, 1 figure
Fitted HBT radii versus space-time variances in flow-dominated models
Creators: name: Frodermann, Evan
name: Heinz, Ulrich
name: Lisa, Michael Annan
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The inability of otherwise successful dynamical models to reproduce the ``HBT radii'' extracted from two-particle correlations measured at the Relativistic Heavy Ion Collider (RHIC) is known as the ``RHIC HBT Puzzle.'' Most comparisons between models and experiment exploit the fact that for Gaussian sources the HBT radii agree with certain combinations of the space-time widths of the source which can be directly computed from the emission function, without having to evaluate, at significant expense, the two-particle correlation function. We here study the validity of this approach for realistic emission function models some of which exhibit significant deviations from simple Gaussian behaviour. By Fourier transforming the emission function we compute the 2-particle correlation function and fit it with a Gaussian to partially mimic the procedure used for measured correlation functions. We describe a novel algorithm to perform this Gaussian fit analytically. We find that for realistic hydrodynamic models the HBT radii extracted from this procedure agree better with the data than the values previously extracted from the space-time widths of the emission function. Although serious discrepancies between the calculated and measured HBT radii remain, we show that a more ``apples-to-apples'' comparison of models with data can play an important role in any eventually successful theoretical description of RHIC HBT data.
description: 12 pages, 16 color figures
Effects of The Ehrlich-Schwoebel Potential Barrier on the Wolf-Villain Model Simulations for Thin Film Growth
Creators: name: Rangdee, Rachan
name: Chatraphorn, Patcha
Publisher: name: arXiv
Year: 2020
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: \emph{Wolf-Villain (WV) model} is a simple model used to study \emph{ideal} molecular beam epitaxy (MBE) growth by using computer simulations. In this model, an adatom diffuses instantaneously within a finite diffusion length to maximize its coordination number. We study statistical properties of thin films grown by this model. The morphology of the WV model is found to be kinetically rough with a downhill particle diffusion current. In real MBE growth, however, there are additional factors such as the existence of a potential barrier that is known as the \emph{Ehrlich-Schwoebel (ES) barrier}. The ES barrier is an additional barrier for an adatom that diffuses over a step edge from the upper to a lower terrace which is known to induce an uphill particle current. We found that with the addition of the ES barrier, the WV-ES model morphology is rough with \emph{mound formation} on the surface when the barrier is strong enough. To confirm these results, the correlation function is also studied. We find no oscillation in the correlation function in the WV model. For the WV-ES model, the correlation function oscillates. These results confirm that a strong enough ES barrier can cause mound formation on the WV surface in our study.
description: 14 pages, 9 figures. This papers already published in 2006 but I just upload to arXiv and update my email to present
Tsallis nonextensive statistical mechanics of El Nino Southern Oscillation Index
Creators: name: Ausloos, M.
name: Petroni, F.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The shape and tails of partial distribution functions (PDF) for a climatological signal, i.e. the El Nino SOI and the turbulent nature of the ocean-atmosphere variability are linked through a model encompassing Tsallis nonextensive statistics and leading to evolution equations of the Langevin and Fokker-Planck type. A model originally proposed to describe the intermittent behavior of turbulent flows describes the behavior of the normalized variability for such a climatological index, for small and large time windows, both for small and large variability. This normalized variabil- ity distributions can be sufficiently well fitted with a chi-square-distribution. The transition between the small time scale model of nonextensive, intermittent process and the large scale Gaussian exten- sive homogeneous fluctuation picture is found to occur at above ca. a 48 months time lag. The intermittency exponent ($κ$) in the framework of the Kolmogorov log-normal model is found to be related to the scaling exponent of the PDF moments. The value of $κ$ (= 0.25) is in agreement with the intermittency exponent recently obtained for other atmospheric data.
description: 34 pages including 57 references; 12 figures; 2 tables; submitted to Physica A
Effect of Coronal Loop Structure on Wave Heating by Phase Mixing
Creators: name: Pagano, P.
name: De Moortel, I.
name: Morton, R. J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The mechanism behind coronal heating still elude direct observation and modelling of viable theoretical processes and the subsequent effect on coronal structures is one of the key tools available to assess possible heating mechanisms. Wave-heating via phase-mixing of Magnetohydrodynamics (MHD) transverse waves has been proposed as a possible way to convert magnetic energy into thermal energy but increasingly, MHD models suggest this is not a sufficiently efficient mechanism. We model heating by phase-mixing of transverse MHD waves in various configurations, to investigate whether certain circumstances can enhance the heating sufficiently to sustain the million degree solar corona and to assess the impact of the propagation and phase-mixing of transverse MHD waves on the structure of the boundary shell of coronal loops. We use 3D MHD simulations of a pre-existing density enhancement in magnetised medium and a boundary driver to trigger the propagation of transverse waves with the same power spectrum as measured by the COmP. We consider different density structures, boundary conditions at the non-drive footpoint, characteristics of the driver, and different forms of magnetic resistivity. We find that different initial density structures affect the evolution of the boundary shell and some driver configurations enhance the heating generated from the dissipation of the MHD waves. In particular, drivers coherent on a larger spatial scale and higher dissipation coefficients generate significant heating, although it is still insufficient. We conclude that while phase-mixing of transverse MHD waves is unlikely to sustain the thermal structure of the corona, there are configurations that allow for an enhanced efficiency of this mechanism. We provide possible signatures to identify the presence of such configurations, such as the location of where the heating is deposited along the coronal loop
Direct mass measurements beyond the proton drip-line
Creators: name: Rauth, C.
name: Ackermann, D.
name: Blaum, K.
name: Block, M.
name: Chaudhuri, A.
name: Eliseev, S.
name: Ferrer, R.
name: Habs, D.
name: Herfurth, F.
name: Hessberger, F. P.
name: Hofmann, S.
name: Kluge, H. -J.
name: Maero, G.
name: Martin, A.
name: Marx, G.
name: Mukherjee, M.
name: Neumayr, J. B.
name: Plass, W. R.
name: Quint, W.
name: Rahaman, S.
name: Rodriguez, D.
name: Scheidenberger, C.
name: Schweikhard, L.
name: Thirolf, P. G.
name: Vorobjev, G.
name: Weber, C.
name: Di, Z.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: First on-line mass measurements were performed at the SHIPTRAP Penning trap mass spectrometer. The masses of 18 neutron-deficient isotopes in the terbium-to-thulium region produced in fusion-evaporation reactions were determined with relative uncertainties of about $7\cdot 10^{-8}$, nine of them for the first time. Four nuclides ($^{144, 145}$Ho and $^{147, 148}$Tm) were found to be proton-unbound. The implication of the results on the location of the proton drip-line is discussed by analyzing the one-proton separation energies.
Μελέτη αποκατάστασης και επανάχρησης της καμένης βορειοανατολικής πτέρυγας – «Λευκό κονάκι» – της Ι.Μ. Χιλανδαρίου Αγίου Όρους
Creators: name: Ρηγόπουλος, Κωνσταντίνος Βασιλείου
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Λευκό κονάκι
Χιλανδάρι
Πτέρυγα περιβόλου
White residence
Chilandar
Wing of precinct

description: Το «Λευκό κονάκι» αποτελεί κτήριο πτέρυγας κελλιών στην ανατολική πλευρά του περιβόλου της μονής Χιλανδαρίου, στο Άγιο Όρος. Η ανοικοδόμησή του έγινε στα τέλη του 16ου αιώνα, την περίοδο δηλαδή που το Άγιο Όρος είχε ενσωματωθεί στην οθωμανική επικράτεια. Από τότε πέρασε διάφορες οικοδομικές φάσεις, οι οποίες άφησαν η καθεμιά τη σφραγίδα της στο κτήριο, αλλά παράλληλα εξασφάλισαν τη διατήρησή του μέχρι τις μέρες μας. Στις 4 Μαρτίου 2004, το «Λευκό κονάκι» κάηκε κατά τη διάρκεια της μεγάλης πυρκαγιάς που κατέστρεψε το μισό μοναστήρι. Στα πλαίσια της παρούσας διπλωματικής του μεταπτυχιακού παρουσιάζεται μια μελέτη αποκατάστασης και επανάχρησης του εν λόγω κτηρίου, το οποίο αποτέλεσε σπάνιο και χαρακτηριστικό δείγμα του είδους και της εποχής του. Σημείο αναφοράς για την αποκατάστασή του αποτελεί η παλαιότερη γνωστή μορφή της όψης του, όπως αυτή απεικονίζεται σε φωτογραφία του 1880. Η μορφή αυτή είναι, συγκριτικά με τις επόμενες, η μόνη συνεπής με την αυθεντική τυπολογία του κτηρίου. Τέλος, επιχειρείται να επιλυθούν αποτελεσματικά τα προβλήματα, που αντιμετώπιζε το κτήριο παλιότερα, με τις αναγκαίες αλλαγές και τροποποιήσεις, κυρίως στον τομέα της λειτουργικότητας.
description: The “White residence” is a building, wing of cells, on the eastern side of the precinct of the Chilandar monastery, on Mount Athos. The reconstruction was made in the late 16th century, the period that the Holy Mountain was incorporated into the Ottoman Empire. Since then it went through several construction phases, each of which left its own stamp on the building, at the same time they ensured the preservation of it until today. On the 4th of March 2004, the “White residence” was burnt down during the great fire that destroyed half of the monastery. As part of this Master’s thesis, a study of restoration and rehabilitation of the building is presented. The building was rare and characteristic specimen of its type and age. Reference point for restoration is the oldest known form of the facade, as shown in a photo of the year 1880. This form, compared to the next that followed, is the only consistent with the authentic typology of the building. Finally, attempts are made to effectively solve the problems that the building was facing in the past, accompanied with the necessary changes and modifications, mainly in terms of functionality.
A List of American Economic Histories
Creators: name: Edwards, Everett E.
name: Edwards, Everett E.
Publisher: name: Unknown
Year: 1939
Subjects: Teaching/Communication/Extension/Profession

description: Excerpts from the Preface: This list of American economic histories is designed primarily for those who need citations of books that afford convenient summaries of the main facts concerning the economic history of the United States. The first edition was issued in November 1935. In order to facilitate the use of this bibliography by persons who have access to the Library of Congress and to the Library of the United States Department of Agriculture, the library call number is given at the end of each citation. Those starting with a letter are for books in the Library of Congress, while those beginning with a numeral are for the Department of Agriculture Library.
Description of nuclear octupole and quadrupole deformation close to the axial symmetry: Critical-point behavior of 224Ra and 224Th
Creators: name: Bizzeti, P. G.
name: Bizzeti-Sona, A. M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Theory (nucl-th)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: The model, introduced in a previous paper, for the description of the octupole and quadrupole degrees of freedom in conditions close to the axial symmetry, is applied to situations of shape phase transitions where the quadrupole amplitude can reach zero. The transitional nuclei 224,226Ra and 224Th are discussed in the frame of this model. Their level schemes can be reasonably accounted for assuming a square-well potential in two dimensions. Electromagnetic transition amplitudes are also evaluated and compared with existing experimental data.
description: 11 pages, 9 figures
The molecular nature of some exotic hadrons
Creators: name: Ramos, A.
name: Feijoo, A.
name: Llorens, Q.
name: Montaña, G.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The exciting discovery by LHCb of the $P_c(4312)^+$ and $P_c(4450)^+$ pentaquarks, or the suggestion of a tetraquark nature for the $Z_c(3900)$ state seen at BESIII and Belle, have triggered a lot of activity in the field of hadron physics, with new experiments planned for searching other exotic mesons and baryons, and many theoretical developments trying to disentangle the true multiquark nature from their possible molecular origin. After a brief review of the present status of these searches, this paper focusses on recently seen or yet to be discovered exotic heavy baryons that may emerge from a conveniently unitarized meson-baryon interaction model in coupled channels. In particular, we will show how interferences between the different coupled-channel amplitudes of the model may reveal the existence of a $N^*$ resonance around 2 GeV having a meson-baryon quasi-bound state nature. We also discuss the possible interpretation of some of the $Ω_c$ states recently discovered at LHCb as being hadron molecules. The model also predicts the existence of doubly-charmed quasibound meson-baryon $Ξ_{cc}$ states, which would be excited states of the ground-state $Ξ_{cc}(3621)$ MeV, whose mass has only been recently established. Extensions of these results to the bottom sector will also be presented.
description: 18 pages, 9 figures, to appear in a Special Issue of Few-Body Systems
Η ελευθερία της βούλησης στον Αριστοτέλη:
Creators: name: Βασιλειάδου, Όλγα Ιωάννη
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Προαίρεση
Εκούσιες πράξεις
Ακρασία
Prohairesis
Voluntary actions
Akrasia

description: Σκοπός της διατριβής ήταν η εξέταση της θέσης του Αριστοτέλη ως προς τη θεωρία της ελευθερίας της βούλησης. Αρχικά μελετώντας τα κείμενα των Ηθικών του διακρίναμε τις πράξεις σε εκούσιες και ακούσιες αλλά και εντοπίσαμε το ρόλο της βίας και της άγνοιας σε σχέση με αυτές. Διαπιστώσαμε ότι αναμφίβολα το θέμα της ελεύθερης βούλησης συνδέεται άμεσα με τον τρόπο που σκέφτεται κάποιος και κατ’ επέκταση παίρνει αποφάσεις. Στο τελευταίο ζήτημα η αριστοτελική έννοια της προαίρεσης κατέχει ύψιστης σημασίας θέση. Στη συνέχεια εξετάζεται η ευθύνη του ανθρώπου σε σχέση με συγκεκριμένες πράξεις του, αφού από αυτήν εξαρτάται αν πράττει ελεύθερα ή όχι ο άνθρωπος και επομένως αν ο Αριστοτέλης είναι αιτιοκράτης ή ελευθεριοκράτης. Τέλος επιχειρήσαμε μια ανάλυση των ζητήματα της ακρασίας και της εγκράτειας.
description: The aim of this study was to examine the position of Aristotle in the theory of free will. Initially studying the texts of Ethics, we distinguished between voluntary and involuntary actions, and we determined the role of violence and ignorance in relation to the actions. We found out that undoubtedly the issue of free will is directly linked to the way someone thinks and thus make decisions. In this last issue the Aristotelian concept of prohairesis held paramount position. Then we examined the responsibility of man in relation to specific actions, since this last influences whether or not man acts freely, and therefore if Aristotle is deterministic or follower of free will. In the end we attempted an analysis of issues akrasia and abstinence.
Ultra long range plasmonic waveguides using quasi two dimensional metallic layers
Creators: name: Plumridge, J.
name: Phillips, C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We calculate the bound plasmonic modes of a quantum metamaterial slab, comprised of multiple quasi two dimensional electron gas (Q2DEG) layers, whose thickness is much smaller than the optical wavelength. For the first order transverse magnetic (TM) optical and the surface plasmonic modes we find propagation constants which are independent of both the electron density and of the scattering rates in the Q2DEGs. This leads to extremely long propagation distances. In a detailed case study of a structure comprising a slab of GaAs/AlGaAs multiple quantum well (MQW) material, we find propagation lengths of 100s of mm. In addition, the electric field enhancement associated with the plasmonic resonance is found to be sufficient to induce the condition of strong coupling between the slab modes and the intersubband transitions in the MQWs.
Carl Rogers: από την ψυχοθεραπεία στην εκπαίδευση
Creators: name: Παπαχρήστου, Αγγελική Αργυρίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Καρλ Ρότζερς
Ψυχοθεραπεία
Εκπαίδευση
Carl Rogers
Psychotherapy
Education

description: Η θεωρία του Carl Rogers χαρακτηρίζεται από τον ίδιο ως μία θεωρία α) της Ψυχοθεραπείας, β) του Προσώπου, και γ) των Διαπροσωπικών Σχέσεων. Στο πλαίσιο της εργασίας διερευνάται το πώς η ποιότητα των σχέσεων που δημιουργεί ο άνθρωπος με τον εαυτό και με τους άλλους, συμβάλλει στην αυτοπραγμάτωσή του, δηλαδή, στην εξέλιξή του σε πλήρες πρόσωπο. Εξετάζεται ο τρόπος που η ροτζεριανή σχέση διευκόλυνσης, εξελισσόμενη σε μία σχεσιοδυναμική μάθηση, καλλιεργεί ιδέες και αντιλήψεις, στάσεις και συμπεριφορές οι οποίες προάγουν διαδικασίες θεραπείας και ανάπτυξης. Η εργασία προσεγγίζει τη ροτζεριανή θεωρία ως μία οπτική, μια φιλοσοφία, μια προσέγγιση ζωής, έναν τρόπο ύπαρξης, που ταιριάζει σε οποιαδήποτε κατάσταση στην οποία η ανάπτυξη ενός προσώπου, μιας ομάδας ή μιας κοινότητας, είναι μέρος του στόχου. Γι’ αυτό και διερευνάται ως μία θεωρία των σχέσεων και της μάθησης, ούσα ικανή να μετουσιωθεί σε μία φιλοσοφία κουλτούρας και ως τέτοια παιδείας.
description: Carl Rogers characterizes his theory as a theory a) of Psychotherapy, b) of the Person, and c) of Interpersonal Relations. This thesis investigates how the quality of relationships, which man creates with himself and with the others, contributes to self-actualization, namely, to the evolution into whole person. It is examined the way in which the rogerian facilitation, being evolving in a dynamic learning relationship cultivates ideas and perceptions, attitudes and behaviors that promote healing and development procedures. This paper approaches the rogerian theory as a perspective, a philosophy, an approach of life, a way of being, which corresponds in any situation, in which the development of a person, a group or community becomes part of the goal. This is the reason it is investigated as a theory of relations and learning, being able to be transmuted into a philosophy of culture and education as such.
The Magellanic Corona and the formation of the Magellanic Stream
Creators: name: Lucchini, Scott
name: D'Onghia, Elena
name: Fox, Andrew J
name: Bustard, Chad
name: Bland-Hawthorn, Joss
name: Zweibel, Ellen
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The dominant gaseous structure in the Galactic halo is the Magellanic Stream, an extended network of neutral and ionized filaments surrounding the Large and Small Magellanic Clouds (LMC/SMC), the two most massive satellite galaxies of the Milky Way. Recent observations indicate that the Clouds are on their first passage around our Galaxy, the Stream is made up of gas stripped from both the LMC and the SMC, and the majority of this gas is ionized. While it has long been suspected that tidal forces and ram-pressure stripping contributed to the Stream's formation, a full understanding of its origins has defied modelers for decades. Several recent developments, including the discovery of dwarf galaxies associated with the Magellanic Group, the high mass of the LMC, the detection of highly ionized gas toward stars in the LMC and the predictions of cosmological simulations all support the existence of a halo of warm ionized gas around the LMC at a temperature of $\sim5\times10^{5}\;\mathrm{K}$. Here we show that by including this "Magellanic Corona" in hydrodynamic simulations of the Magellanic Clouds falling onto the Galaxy, we can simultaneously reproduce the Stream and its Leading Arm. Our simulations explain the Stream's filamentary structure, spatial extent, radial velocity gradient, and total ionized gas mass. We predict that the Magellanic Corona will be unambiguously observable via high-ionization absorption lines in the ultraviolet spectra of background quasars lying near the LMC. This prediction is directly testable with the Cosmic Origins Spectrograph on the Hubble Space Telescope.
description: 32 pages, 7 figures. Published in the September 20 issue of Nature. This is the authors' version before final edits. Published version is available at https://www.nature.com/articles/s41586-020-2663-4
The luminosity bias relation from filaments in the Sloan Digital Sky Survey Data Release Four
Creators: name: Pandey, Biswajit
name: Bharadwaj, Somnath
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We compare quantitative estimates of the filamentarity of the galaxy distribution in seven nearly two dimensional sections from the survey against the predictions of LCDM N-body simulations. The filamentarity of the actual galaxy distribution is known to be luminosity dependent. It is also known that the filamentarity of the simulated galaxy distribution is highly sensitive to the bias, and the simulations are consistent with the data for only a narrow range of bias. We apply this feature to several volume limited subsamples with different luminosities to determine a luminosity bias relation. The relative bias $b/b^*$ as a function of the luminosity ratio $L/L^*$ is found to be well described by a straight line $b/b^*=A + B (L/L^*)$ with $A=0.833 \pm 0.009$ and $B=0.171 \pm 0.009$. Comparing with the earlier works all of which use ratios of the two-point statistics, we find that our results are consistent with Norberg et al.(2001) and Tegmark et al.(2004), while a steeper luminosity dependence found by Benoist et al.(1996) is inconsistent.
description: Published in MNRAS Letters, accepted version, one reference added, 5 pages, 3 figures and 2 tables
Η Δικονομία του Ελεγκτικού Συνεδρίου
Creators: name: Παναγιώτου, Δημήτριος Γεωργίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Ελεγκτικό Συνέδριο
Διοικητικό Δίκαιο
Δικονομία
Court of Auditors
Administrative Law
Procedure

description: Η διπλωματική εργασία αφορά στην δικονομία του Ελληνικού Ελεγκτικού Συνεδρίου, όπως αυτή διαμορφώθηκε πριν από τη θέση σε ισχύ του ν. 4055/2012. Ειδικότερα, γίνεται μια ανάλυση κατά άρθρο τόσο του π.δ. 774/1980, όσο και του π.δ.1225/1981.
description: The thesis concerns the procedure of the Greek Court of Auditors, as established before the entry into force of Law 4055/2012. Specifically, it is an analysis per article of both the Presidential Degrees 774/1980, and 1225/1981.
Zero-energy states of N = 4 SYM on T^3: S-duality and the mapping class group
Creators: name: Henningson, Mans
name: Wyllard, Niclas
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We continue our studies of the low-energy spectrum of N=4 super-Yang-Mills theory on a spatial three-torus. In two previous papers, we computed the spectrum of normalizable zero-energy states for all choices of gauge group and all values of the electric and magnetic 't Hooft fluxes, and checked its invariance under the SL_2(Z) S-duality group. In this paper, we refine the analysis by also decomposing the space of bound states into irreducible unitary representations of the SL_3(Z) mapping class group of the three-torus. We perform a detailed study of the S-dual pairs of theories with gauge groups Spin(2n+1) and Sp(2n). The predictions of S-duality (which commutes with the mapping class group) are fulfilled as expected, but the proof requires some surprisingly intricate combinatorial infinite product identities.
description: 17 pages
Obtaining cosmic ray propagation parameters from diffuse VHE gamma ray emission from the Galactic center ridge
Creators: name: Büsching, I.
name: de Jager, O. C.
name: Snyman, J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The recent discovery of diffuse, VHE gamma radiation from the Galactic center ridge by the H.E.S.S. telescope allow for the first time the direct determination of parameters of galactic cosmic ray propagation models. In this paper we show that the diffuse gamma radiation near the Galactic center may be explained by the interaction of VHE cosmic ray (CR) protons with the interstellar gas located in several giant molecular clouds leading to a measurement of the cosmic ray diffusion coefficient for the galactic center region of k = 1.3 kpc^2 Myr^-1 for a mean proton energy of about 3 TeV, if we assume that the CR protons originated from a supernova event (Sgr A East), which took off about 10 kyr ago. This value of k is about 5 to 10 times smaller than the locally measured value.
description: 10 pages, 3 figures, aastex, submitted to ApJL
Looking for bimodal distributions in multi-fragmentation reactions
Creators: name: Gulminelli, F.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The presence of a phase transition in a finite system can be deduced, together with its order, from the shape of the distribution of the order parameter. This issue has been extensively studied in multifragmentation experiments, with results that do not appear fully consistent. In this paper we discuss the effect of the statistical ensemble or sorting conditions on the shape of fragment distributions, and propose a new method, which can be easily implemented experimentally, to discriminate between different fragmentation scenarii. This method, based on a reweighting of the measured distribution to account for the experimental constraints linked to the energy deposit, is tested on different simple models, and appears to provide a powerful discrimination.
description: 11 pages, 7 figures
Milagro Search for Very High Energy Emission from Gamma-Ray Bursts in the Swift Era
Creators: name: Parkinson, P. M. Saz
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The recently launched Swift satellite is providing an unprecedented number of rapid and accurate Gamma-Ray Burst (GRB) localizations, facilitating a flurry of follow-up observations by a large number of telescopes at many different wavelengths. The Very High Energy (VHE, >100 GeV) regime has so far been relatively unexplored. Milagro is a wide field of view (2 sr) and high duty cycle (> 90%) ground-based gamma-ray telescope which employs a water Cherenkov detector to monitor the northern sky almost continuously in the 100 GeV to 100 TeV energy range. We have searched the Milagro data for emission from the most recent GRBs identified within our field of view. These include three Swift bursts which also display late-time X-ray flares. We have searched for emission coincident with these flares. No significant detection was made. A 99% confidence upper limit is provided for each of the GRBs, as well as the flares.
description: To be published in AIP Conference Proceedings "Gamma Ray Bursts in the Swift Era," Nov. 29 - Dec. 2, 2005, Washington, DC
Πειραματική αξιολόγηση και αυτοματοποιημένη βελτίωση των μετρήσεων της μηχανής απεικόνισης αποστάσεων Swiss Ranger 4000 σε συνδυασμό με στερεοσκοπική διάταξη:
Creators: name: Νάσκου-Αθανάσιος, Κωνσταντίνος Σταύρου
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Μηχανές Απεικόνισης Αποστάσεων
Τρισδιάστατη Σάρωση
Φωτογραμμετρία
Range Imaging Cameras
3D Scanning
Photogrammetry

description: Οι μηχανές απεικόνισης αποστάσεων αποτελούν την τεχνολογία αιχμής στο πεδίο της τρισδιάστατης σάρωσης αντικειμένων με υψηλό ρυθμό ανανέωσης. Για την αξιολόγηση της ποιότητας, την βελτίωση και την εκμετάλλευσή των μετρητικών δεδομένων της μηχανής απεικόνισης αποστάσεων SwissRanger 4000 σε συνδυασμό με στεροσκοπική διάταξη αναπτύχθηκε εφαρμογή σε περιβάλλον Matlab. Σκοπός του εγχειρήματος ήταν η διεξαγωγή και η περαιτέρω επεξεργασία των μετρήσεων της σε πραγματικό χρόνο, χωρίς να είναι απαραίτητη η χρήση διαφορετικών πακέτων λογισμικού υψηλού κόστους. Η εφαρμογή αυτοματοποιεί τη διαδικασία βαθμονόμησης του συστήματος των τριών αισθητήρων με χρήση επίπεδων και τρισδιάστατων διατάξεων. Εισάγει χρωματική πληροφορία στο νέφος σημείων της SwissRanger 4000 και συνδέει νέφη σημείων από διαφορετικές θέσεις λήψης. Παρέχει επίσης λειτουργίες φιλτραρίσματος για την απομάκρυνση των εσφαλμένων μετρήσεων λαμβάνοντας υπόψη τα ιδιαίτερα χαρακτηριστικά των πηγών σφαλμάτων των μηχανών απεικόνισης αποστάσεων. Τέλος υλοποιείται μια αλγοριθμική διαδικασία για την ανάκτηση μιας παραμορφωμένης αναπτυκτής επιφάνειας η οποία έχει αποτυπωθεί με την SwissRanger 4000 και τους οπτικούς αισθητήρες.
description: Range imaging cameras are the state of the art in the field of three dimensional scanning of objects with high frame rate. In order to evaluate the quality, enhance and utilize the data output of the range imaging camera SwissRanger 4000, in conjunction with a pair of video cameras which create a stereoscopic set up, a software application was developed using Matlab. The aim of the project was the realization and further processing of the measurements in real time without the need to use high cost software packages.The application automates the calibration process of the three sensors system using flat and three dimensional rigs. It adds color information in the SwissRanger’s 4000 point cloud and registers point clouds acquired from different scanning positions. It also provides filtering functions for erroneous point removal taking into consideration the properties of the range imaging cameras’ error sources. Finally an algorithmic approach is proposed to unfold a distorted developable surface, measured by the SwissRanger 4000 and the accompanying set of video cameras.
Top-Rank-Focused Adaptive Vote Collection for the Evaluation of Domain-Specific Semantic Models
Creators: name: Lombardo, Pierangelo
name: Boiardi, Alessio
name: Colombo, Luca
name: Schiavone, Angelo
name: Tamagnone, Nicolò
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computation and Language (cs.CL)
subject: Information Retrieval (cs.IR)
subject: Machine Learning (cs.LG)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences
subject: I.2.7; G.3; I.6.3; I.2.1; J.4
subject: 68T50 (Primary), 62P99, 60G15 (Secondary)

description: The growth of domain-specific applications of semantic models, boosted by the recent achievements of unsupervised embedding learning algorithms, demands domain-specific evaluation datasets. In many cases, content-based recommenders being a prime example, these models are required to rank words or texts according to their semantic relatedness to a given concept, with particular focus on top ranks. In this work, we give a threefold contribution to address these requirements: (i) we define a protocol for the construction, based on adaptive pairwise comparisons, of a relatedness-based evaluation dataset tailored on the available resources and optimized to be particularly accurate in top-rank evaluation; (ii) we define appropriate metrics, extensions of well-known ranking correlation coefficients, to evaluate a semantic model via the aforementioned dataset by taking into account the greater significance of top ranks. Finally, (iii) we define a stochastic transitivity model to simulate semantic-driven pairwise comparisons, which confirms the effectiveness of the proposed dataset construction protocol.
description: This is a pre-print of an article published in the proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP)
Performance of HPGe Detectors in High Magnetic Fields
Creators: name: Lorente, A. Sanchez
name: Achenbach, P.
name: Agnello, M.
name: Bressani, T.
name: Bufalino, S.
name: Cederwall, B.
name: Feliciello, A.
name: Ferro, F.
name: Gerl, J.
name: Iazzi, F.
name: Kavatsyuk, M.
name: Kojouharov, I.
name: Majling, L.
name: Pantaleo, A.
name: Palomba, M.
name: Pochodzalla, J.
name: Raciti, G.
name: Saito, N.
name: Saito, T. R.
name: Schaffner, H.
name: Sfienti, C.
name: Szymanska, K.
name: Tegnér, P. -E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: A new generation of high-resolution hypernuclear gamma$-spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DAPhiNE, the Frascati phi-factory, and at PANDA, the antiproton proton hadron spectrometer at the future FAIR facility. Both, the FINUDA and PANDA spectrometers are built around the target region covering a large solid angle. To maximise the detection efficiency the HPGe detectors have to be located near the target, and therefore they have to be operated in strong magnetic fields B ~ 1 T. The performance of HPGe detectors in such an environment has not been well investigated so far. In the present work VEGA and EUROBALL Cluster HPGe detectors were tested in the field provided by the ALADiN magnet at GSI. No significant degradation of the energy resolution was found, and a change in the rise time distribution of the pulses from preamplifiers was observed. A correlation between rise time and pulse height was observed and is used to correct the measured energy, recovering the energy resolution almost completely. Moreover, no problems in the electronics due to the magnetic field were observed.
description: submitted to Nucl. Instrum. Meth. Phys. Res. A, LaTeX, 19 pages, 9 figures
Η Σημασία του Έρωτα στο «Συμπόσιο» και στο «Φαίδρο» του Πλάτωνα
Creators: name: Κωφίδου, Χριστίνα Παναγιώτη
Publisher: name: Aristotle University of Thessaloniki
Year: 2012
Subjects: Συμπόσιο
Φαίδρος
Έρωτας
Symposium
Phaedrus
Love

description: Σκοπός της παρούσας διατριβής ήταν η διερεύνηση του θέματος του έρωτα στο Συμπόσιο και το Φαίδρο του Πλάτωνα. Αρχικά, υπογραμμίσαμε τη σημασία και τις διάφορες διαστάσεις του έρωτα κατά την αρχαιότητα. Αφού παραθέσαμε ορισμένες πληροφορίες για τη βιογραφία και την εργογραφία του Πλάτωνα, παρουσιάσαμε αναλυτικά τη θεματολογία και τη δομή του Συμποσίου. Συγκεκριμένα, εξετάσαμε τους λόγους όλων των συμμετεχόντων στο Συμπόσιο, δηλαδή του Φαίδρου, του Παυσανία, του Ερυξίμαχου, του Αριστοφάνη, του Αγάθωνα, του Σωκράτη και του Αλκιβιάδη. Ακόμη, κάναμε λόγο για την ιστορία της Διοτίμας για τον έρωτα και για την έννοια του έρωτα ως δαίμονα, του έρωτα της αθανασίας και του έρωτα ως φιλοσόφου. Στη συνέχεια, περάσαμε στην ανάλυση του Φαίδρου. Σε ένα πρώτο στάδιο, παρουσιάσαμε τη δομή και τη θεματολογία του. Κατόπιν, ερμηνεύσαμε τις θέσεις των πρωταγωνιστών του έργου για τον έρωτα, δηλαδή του Λυσία και του Σωκράτη. Θίξαμε, επίσης, το θέμα των ερωτικών σχέσεων, τη σχέση του έρωτα και του λόγου, καθώς και την έννοια του έρωτα ως ορμής και καταλήξαμε σε ορισμένα συμπεράσματα σχετικά με τη φύση, την αξία και τη διαχρονική δύναμη του έρωτα.
description: The aim of the present thesis was the investigation of the subject of love in Plato’s Symposium and Phaedrus. Initially, we underlined the importance and the various dimensions of love during the antiquity. After we had mentioned certain information about the biography and ergography of Plato, we analytically presented the issues and the structure of the Symposium. Specifically, we examined the speeches of all participants in the Symposium, that is to say Phaedrus’, Pausanias’, Eryximachos’, Aristophanes’, Agathon’ s, Socrates’ and Alcibiades’. We also mentioned Diotima’ s history for love and the concept of love as demon, love of immortality and love as philosopher. Subsequently, we analyzed Phaedrus. In a first stage, we presented the structure and its subjects. Then, we interpreted the points of views of the play’s protagonists concerning love, that is to say Lysias’ and Socrates’. We also examined the subject of erotic relations, the connection between love and logic, as well as the significance of love as impetus and arrived at certain conclusions regarding the nature, the value and the lasting force of love.
Micromagnetic instabilities in spin-transfer switching of perpendicular magnetic tunnel junctions
Creators: name: Statuto, Nahuel
name: Mohammadi, Jamileh Beik
name: Kent, Andrew D.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: Micromagnetic instabilities and non-uniform magnetization states play a significant role in spin transfer induced switching of nanometer scale magnetic elements. Here we model domain wall mediated switching dynamics in perpendicularly magnetized magnetic tunnel junction nanopillars. We show that domain wall surface tension always leads to magnetization oscillations and instabilities associated with the disk shape of the junction. A collective coordinate model is developed that captures aspects of these instabilities and illustrates their physical origin. Model results are compared to those of micromagnetic simulations. The switching dynamics is found to be very sensitive to the domain wall position and phase, which characterizes the angle of the magnetization in the disk plane. This sensitivity is reduced in the presence of spin torques and the spin current needed to displace a domain wall can be far less than the threshold current for switching from a uniformly magnetized state. A prediction of this model is conductance oscillations of increasing frequency during the switching process.
Scattering theory for stationary materials with $\mathcal{PT}$ symmetry
Creators: name: Brandão, Paulo
name: Korotkova, Olga
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mathematical Physics (math-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: A theoretical framework is developed for scattering of scalar radiation from stationary, three-dimensional media with correlation functions of scattering potentials obeying $\mathcal{PT}$-symmetry. It is illustrated that unlike in scattering from deterministic $\mathcal{PT}$-symmetric media, its stationary generalization involves two mechanisms leading to symmetry breaking in the statistics of scattered radiation, one stemming from the complex-valued medium realizations and the other - from the complex-valued degree of medium's correlation.
description: 8 pages, 5 figures
Social tipping processes for sustainability: An analytical framework
Creators: name: Winkelmann, Ricarda
name: Donges, Jonathan F.
name: Smith, E. Keith
name: Milkoreit, Manjana
name: Eder, Christina
name: Heitzig, Jobst
name: Katsanidou, Alexia
name: Wiedermann, Marc
name: Wunderling, Nico
name: Lenton, Timothy M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: Societal transformations are necessary to address critical global challenges, such as mitigation of anthropogenic climate change and reaching UN sustainable development goals. Recently, social tipping processes have received increased attention, as they present a form of social change whereby a small change can shift a sensitive social system into a qualitatively different state due to strongly self-amplifying (mathematically positive) feedback mechanisms. Social tipping processes have been suggested as key drivers of sustainability transitions emerging in the fields of technological and energy systems, political mobilization, financial markets and sociocultural norms and behaviors. Drawing from expert elicitation and comprehensive literature review, we develop a framework to identify and characterize social tipping processes critical to facilitating rapid social transformations. We find that social tipping processes are distinguishable from those of already more widely studied climate and ecological tipping dynamics. In particular, we identify human agency, social-institutional network structures, different spatial and temporal scales and increased complexity as key distinctive features underlying social tipping processes. Building on these characteristics, we propose a formal definition for social tipping processes and filtering criteria for those processes that could be decisive for future trajectories to global sustainability in the Anthropocene. We illustrate this definition with the European political system as an example of potential social tipping processes, highlighting the potential role of the FridaysForFuture movement. Accordingly, this analytical framework for social tipping processes can be utilized to illuminate mechanisms for necessary transformative climate change mitigation policies and actions.
description: 24 pages, 4 figures