cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Global Existence of Bi-Hamiltonian Structures on Orientable Three-Dimensional Manifolds
Creators: name: Efe, Melike Işim
name: Abadoğlu, Ender
Publisher: name: arXiv
Year: 2016
Subjects: subject: Symplectic Geometry (math.SG)
subject: FOS: Mathematics
subject: 53D17, 53D35

description: In this work, we show that an autonomous dynamical system defined by a nonvanishing vector field on an orientable three-dimensional manifold is globally bi-Hamiltonian if and only if the first Chern class of the normal bundle of the given vector field vanishes. Furthermore, the bi-Hamiltonian structure is globally compatible if and only if the Bott class of the complex codimension one foliation defined by the given vector field vanishes.
Impact of quadrupole deformation on intermediate-energy heavy-ion collisions
Creators: name: Fan, Xiao-Hua
name: Yang, Zu-Xing
name: Chen, Peng-Hui
name: Nishimura, Shunji
name: Li, Zhi-Pan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: This study employs the isospin-dependent Boltzmann-Uehling-Uhlenbeck model to simulate intermediate-energy heavy-ion collisions between prolate nuclei $^{24}$Mg. The emphasis is on investigating the influence of centrality and orientation in several collision scenarios. The final-state particle multiplicities and anisotropic flows are primarily determined by the eccentricity and the area of the initial overlap. This not only provides feedback on the collision systems, but also, to some extent, provides a means to explore the fine structure inside deformed nuclei. Additionally, non-polarized collisions have been further discussed. These results contribute to the understanding of the geometric effects in nuclear reactions, and aid in the exploration of other information on reaction systems, such as the equation of state and nuclear high-momentum tail.
Quantitative vectorial magnetic imaging of multi domain rock forming minerals using nitrogen-vacancy centers in diamond
Creators: name: Farchi, E.
name: Ebert, Y.
name: Farfurnik, D.
name: Haim, G.
name: Shaar, R.
name: Bar-Gill, N.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Magnetization in rock samples is crucial for paleomagnetometry research, as it harbors valuable geological information on long term processes, such as tectonic movements and the formation of oceans and continents. Nevertheless, current techniques are limited in their ability to measure high spatial resolution and high-sensitivity quantitative vectorial magnetic signatures from such samples. As a result, our understanding of this magnetization is limited, specifically for the case of multi-domain samples. In this work we use a newly developed nitrogen-vacancy magnetic microscope, capable of quantitative vectorial magnetic imaging with optical resolution. We demonstrate direct imaging of the vectorial magnetic field of a single, multi-domain dendrite, as well as the measurement and calculation of the weak magnetic moments of individual grains on the micron scale. These results pave the way for future applications in paleomagnetometry, and for the fundamental understanding of magnetization in multi-domain samples.
Let's Play Together through Channels: Understanding the Practices and Experience of Danmaku Participation Game Players in China
Creators: name: Wang, Piaohong
name: Lu, Zhicong
Publisher: name: arXiv
Year: 2023
Subjects: subject: Human-Computer Interaction (cs.HC)
subject: FOS: Computer and information sciences

description: Live streaming is becoming increasingly popular in recent years, as most channels prioritize the delivery of engaging content to their viewers. Among various live streaming channels, Danmaku participation game (DPG) has emerged in China as a mixture of live streaming and online gaming, offering an immersive gaming experience to players. Although prior research has explored audience participation games (APGs) in North America and Europe, it primarily focuses on discussing prototypes and lacks observation of players in natural settings. Little is known about how players perceive DPGs and their player experience. To fill the research gap, we observed a series of DPG channels and conducted an interview-based study to gain insights into the practices and experiences of DPG players. Our work reveals that DPGs can effectively synergize live streaming and online games, amplifying both player engagement and a profound sense of accomplishment to players.
The non-ordinary Regge behavior of the K*0(800) or Kappa-meson versus the ordinary K*0(1430)
Creators: name: Pelaez, J. R.
name: Rodas, A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The Regge trajectory of an elastic resonance can be calculated from dispersion theory, instead of fitted phenomenologically, using only its pole parameters as input. This also provides a correct treatment of resonance widths in Regge trajectories, essential for very wide resonances. In this work we first calculate the K*0(1430) Regge trajectory, finding the ordinary almost real and linear behavior, typical of quark-antiquark resonances. In contrast, for the K*0(800) meson, the resulting Regge trajectory is non-linear and has a much smaller slope than ordinary resonances, being remarkably similar to that of the f0(500) or sigma meson. The slope of these unusual Regge trajectories seems to scale with the meson masses rather than with scales typical of quark degrees of freedom. We also calculate the range of the interaction responsible for the formation of these resonances. Our results strongly support a non-ordinary, predominantly meson-meson-like, interpretation for the lightest strange and non-strange resonances.
description: 11 pages, 5 Figures. Extended discussion on applicability regime and minor typos corrected. Version to appear in EPJC
title: Η αποδοχή του social media marketing από τις μικρομεσαίες επιχειρήσεις στην Ελλάδα
title: Social media marketing adoption by SMES in Greece
titleType: AlternativeTitle
Creators: name: Τσαλδάρης, Δημήτριος
Publisher: name: Πανεπιστήμιο Δυτικής Αττικής
Year: 2023
Subjects: Social media marketing
Στρατηγική μάρκετινγκ
Μικρομεσαίες επιχειρήσεις
Μέσα κοινωνικής δικτύωσης
Μάρκετινγκ

description: Οι μικρομεσαίες επιχειρήσεις είναι η ραχοκοκαλιά της ελληνικής οικονομίας και στην ατέρμονη προσπάθεια τους να ηγηθούν ή να παραμείνουν ανταγωνιστικές στον κλάδο τους, κάνουν άοκνες προσπάθειες να βρουν το καλύτερο μείγμα Marketing. Σε αυτό το πλαίσιο μπορούν να υιοθετήσουν και να χρησιμοποιήσουν τα μέσα κοινωνικής δικτύωσης με στόχο την αλληλεπίδραση για τον διαμοιρασμό πληροφοριών με το μικρότερο δυνατό κόστος. Είναι ήδη ευρέως γνωστό, από παλαιότερες έρευνες, ότι η δυνατότητα πρόσβασης και ανταλλαγής πληροφοριών επηρεάζουν άμεσα τα οικονομικά επιτεύγματα των μικρομεσαίων επιχειρήσεων αλλά υπάρχει ένα μεγάλο γνωστικό κενό στην υιοθέτηση των Μέσων Κοινωνικής Δικτύωσης σε σχέση με αυτές τις δυνατότητες. Στην παρούσα μελέτη έγινε μια ανασκόπηση των εννοιών του Marketing, παρουσιάστηκε η ελληνική και ευρωπαϊκή κατάσταση, μελετήθηκαν παλαιότερες έρευνες που έχουν γίνει παγκοσμίως και τέλος ερευνήθηκε μέσω ερωτηματολογίου σε μικρομεσαίες επιχειρήσεις, η ελληνική πραγματικότητα. Πιο συγκεκριμένα απάντησαν 276 στελέχη επιχειρήσεων για την υιοθέτηση του Social Media Marketing και των παραγόντων (Τεχνολογικών, Οργανωτικών και Περιβαλλοντικών) που επηρεάζουν και πόσο την απόδοση της επιχείρησης στην οποία εργάζονται. Τέλος αναλύονται τα συμπεράσματα της έρευνας και γίνονται προτάσεις για την αλλαγή του μείγματος marketing και για περαιτέρω έρευνα στην Ελλάδα.
The Cosmic Energy Flow Model: A Theory of Universal Energy Recycling
Creators: name: Hubbuck, Robert Michael
Publisher: name: Zenodo
Year: 2025

description: Abstract

This paper proposes the Cosmic Energy Flow Model, a scientific theory describing the universe as a system that continuously recycles and transforms energy through large-scale structures. Dark matter acts as a stabilizing and energy-accumulating force, while black holes act as collectors and transformers of mass-energy. Together, they drive a cyclic process of accumulation, compression, and redistribution, sustaining the long-term evolution and rebirth of cosmic structures. This model refines standard cosmological theories by introducing mechanisms for energy conservation and structural renewal beyond classical Big Bang, Heat Death, or Big Rip scenarios.
A Generic Fundus Image Enhancement Network Boosted by Frequency Self-supervised Representation Learning
Creators: name: Li, Heng
name: Liu, Haofeng
name: Fu, Huazhu
name: Xu, Yanwu
name: Shu, Hui
name: Niu, Ke
name: Hu, Yan
name: Liu, Jiang
Publisher: name: arXiv
Year: 2023
Subjects: subject: Image and Video Processing (eess.IV)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: Fundus photography is prone to suffer from image quality degradation that impacts clinical examination performed by ophthalmologists or intelligent systems. Though enhancement algorithms have been developed to promote fundus observation on degraded images, high data demands and limited applicability hinder their clinical deployment. To circumvent this bottleneck, a generic fundus image enhancement network (GFE-Net) is developed in this study to robustly correct unknown fundus images without supervised or extra data. Levering image frequency information, self-supervised representation learning is conducted to learn robust structure-aware representations from degraded images. Then with a seamless architecture that couples representation learning and image enhancement, GFE-Net can accurately correct fundus images and meanwhile preserve retinal structures. Comprehensive experiments are implemented to demonstrate the effectiveness and advantages of GFE-Net. Compared with state-of-the-art algorithms, GFE-Net achieves superior performance in data dependency, enhancement performance, deployment efficiency, and scale generalizability. Follow-up fundus image analysis is also facilitated by GFE-Net, whose modules are respectively verified to be effective for image enhancement.
description: Accepted by Medical Image Analysis in Auguest, 2023
title: Η διαχείριση της κρίσης δημόσιου χρέους στην Ελλάδα από το 2010 έως σήμερα
title: The management of public debt crisis in Greece from 2010 to the present day
titleType: AlternativeTitle
Creators: name: Λευκιμμιάτη, Σπυριδούλα
Publisher: name: Πανεπιστήμιο Δυτικής Αττικής
Year: 2023
Subjects: Δημόσιο χρέος
Κρίση χρέους
Αναδιάρθρωση χρέους
ΑΕΠ
Μνημόνιο
Ανακεφαλαιοποίηση τραπεζών
Δημοσιονομική μεταρρύθμιση
Μεταμνημονιακή εποπτεία
Προϋπολογισμός
Βιωσιμότητα χρέους
Φορείς Γενικής Κυβέρνησης

description: Σκοπός της παρούσας εργασίας είναι να εξετάσει τον τρόπο με τον οποίο η Ελλάδα, ούσα μέλος από το 2001 της Οικονομικής και Νομισματικής Ένωσης (Ο.Ν.Ε.),αντιμετώπισε τη δίνη της κρίσης χρέους, στην οποία περιήλθε στα τέλη του 2009.H σημαντικότητα του θέματος αποδεικνύεται από το γεγονός ότι η κρίση χρέους που αντιμετώπισε η Ελλάδα είχε δραματικές επιπτώσεις σε όλους σχεδόν τους οικονομικούς δείκτες. Συρρικνώθηκε το ΑΕΠ της χώρας κατά 25% με αποτέλεσμα να αυξηθεί κατακορύφως ο λόγος του δημόσιου χρέους προς το ΑΕΠ, η ανεργία εκτοξεύτηκε, με επακόλουθο τη μαζική μετανάστευση μορφωμένων Ελλήνων (brain drain).Το χρονικό διάστημα της εν λόγω κρίσης ήταν πάνω από μια δεκαετία, ενώ ακόμη και σήμερα το φάντασμα της κρίσης εξακολουθεί να αιωρείται, ιδιαίτερα λόγω της επίδρασης της πανδημίας covid-19, της παγκόσμιας ενεργειακής κρίσης, καθώς και της πρόσφατης νέας τραπεζικής κρίσης που ενέσκηψε τον Μάρτιο του 2023 σε διεθνές επίπεδο. Στο παρόν πόνημα αναλύεται η επίδραση των τριών μνημονίων που υπέγραψε η χώρα με τους δανειστές (Ευρωπαϊκή Ένωση και Διεθνές Νομισματικό Ταμείο) εξαιτίας του αποκλεισμού της από τις διεθνείς χρηματοπιστωτικές αγορές . Εξετάζεται επίσης η επίδραση της αναδιάρθρωσης του δημόσιου χρέους της Ελλάδας μέσω του PSI(Private Sector Involment) στο μέγεθος του ελληνικού χρέους. Μελετάται επίσης η περίπτωση της ανακεφαλαιοποίηση των ελληνικών τραπεζών το 2015. Επιπρόσθετα, επιχειρείται η αξιολόγηση των αλλαγών στο δημοσιονομικό πλαίσιο της χώρας, και κατά πόσον αυτές συνέβαλλαν στον εξορθολογισμό των δημοσίων οικονομικών. Λαμβανομένων δε υπόψη των τωρινών επικρατουσών συνθηκών στο παγκόσμιο οικονομικό γίγνεσθαι και του υφιστάμενου μεγέθους του χρέους της Ελλάδας θα αναλυθεί το κρίσιμο ερώτημα της βιωσιμότητας του. Για την εκπόνηση της παρούσας εργασίας έγινε εμπειρική ανάλυση με δεδομένα από έρευνες σε ελληνική και ξενόγλωσση βιβλιογραφία και επίσημες ιστοσελίδες. Τα οικονομικά και στατιστικά στοιχεία αναζητήθηκαν από διεθνείς οργανισμούς όπως ο ΟΟΣΑ (OECD), η ΕΛΣΤΑΤ, EUROSTAT. Χρησιμοποιήθηκε επίσης εξιδεικευμένο ερωτηματολόγιο που απεστάλη σε υπαλλήλους οικονομικών υπηρεσιών της Διοίκησης καθώς και σε μεταπτυχιακούς φοιτητές οικονομικής κατεύθυνσης με καλή γνώση του πεδίου της έρευνας.
Relativistic sonic geometry for isothermal accretion in the Schwarzschild metric
Creators: name: Shaikh, Md Arif
name: Firdousi, Ivleena
name: Das, Tapas K.
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: In this work, we perform linear perturbation on general relativistic isothermal accretion onto a non-rotating astrophysical black hole to study the salient features of the corresponding emergent acoustic metric. For spherically symmetric accretion as well as for the axially symmetric matter flow for three different geometric configuration of matter, we perturb the velocity potential, the mass accretion rate, and the integral solution of the time independent part of the general relativistic Euler equation to obtain such acoustic geometry. We provide the procedure to locate the acoustic horizon and identify such horizon with the transonic surfaces of the accreting matter through the construction of the corresponding causal structures. We then discuss how one can compute the value of the acoustic surface gravity in terms of the accretion variable corresponding to the background flow solutions - i.e., stationary integral transonic accretion solutions for different matter geometries. We show that the salient features of the acoustic geometry is independent of the physical variable we perturb, but sensitively depends on the geometric configuration of the black hole accretion disc.
description: 34 pages, 2 figures, completely rewritten, several new sections added
Selected U.S. Crop Budgets: Yields, Inputs and Variable Costs, Volume I, Southeast Region
Creators: name: McArthur, W. C.
name: McArthur, W. C.
Publisher: name: Unknown
Year: 1971
Subjects: subject: Crop Production/Industries
subject: Labor and Human Capital
subject: Production Economics
subject: Productivity Analysis
subject: Research Methods/ Statistical Methods
subject: Crop costs
subject: Crop budgets
subject: Production costs
subject: Southeast region

description: This report contains estimates of variable costs of producing major crops in nine production areas in the Southeast region of the United States. Crops include cotton, corn, soybeans, wheat, oats, barley, grain sorghum, peanuts, and tobacco. Budgets show the quantity and value of specific preharvest and harvest inputs, total preharvest costs per acre planted, and total variable costs per acre planted. Detailed breakdowns of seasonal labor use, crop yields, and rates of fertilization are also included.
Transition Jitter in Heat Assisted Magnetic Recording by Micromagnetic Simulation
Creators: name: Oezelt, Harald
name: Kovacs, Alexander
name: Fischbacher, Johann
name: Bance, Simon
name: Gubbins, Mark
name: Schrefl, Thomas
Publisher: name: arXiv
Year: 2017
Subjects: subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: In this paper we apply an extended Landau-Lifschitz equation, as introduced by Baňas et al. for the simulation of heat-assisted magnetic recording. This equation has similarities with the Landau-Lifshitz-Bloch equation. The Baňas equation is supposed to be used in a continuum setting with sub-grain discretization by the finite-element method. Thus, local geometric features and nonuniform magnetic states during switching are taken into account. We implement the Baňas model and test its capability for predicting the recording performance in a realistic recording scenario. By performing recording simulations on 100 media slabs with randomized granular structure and consecutive read back calculation, the write position shift and transition jitter for bit lengths of 10nm, 12nm, and 20nm are calculated.
description: 5 pages, 3 figures, IEEE International Magnetics Conference INTERMAG 2017
Enhancing Photon Correlations through Plasmonic Strong Coupling
Creators: name: Sáez-Blázquez, R.
name: Feist, J.
name: Fernández-Domínguez, A. I.
name: García-Vidal, F. J.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: There is an increasing scientific and technological interest on the design and implementation of nanoscale sources of quantum light. Here, we investigate the quantum statistics of the light scattered from a plasmonic nanocavity coupled to a mesoscopic ensemble of emitters under low coherent pumping. We present an analytical description of the intensity correlations taking place in these systems, and unveil the fingerprint of plasmon-exciton-polaritons in them. Our findings reveal that plasmonic cavities are able to retain and enhance excitonic nonlinearities even when the number of emitters is large. This makes plasmonic strong coupling a promising route for generating nonclassical light beyond the single emitter level.
description: 5 pages, 4 figures and Supplemental Material
Error bounds for monomial convexification in polynomial optimization
Creators: name: Adams, Warren
name: Gupte, Akshay
name: Xu, Yibo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics
subject: 90C26, 65G99, 52A27

description: Convex hulls of monomials have been widely studied in the literature, and monomial convexifications are implemented in global optimization software for relaxing polynomials. However, there has been no study of the error in the global optimum from such approaches. We give bounds on the worst-case error for convexifying a monomial over subsets of $[0,1]^n$. This implies additive error bounds for relaxing a polynomial optimization problem by convexifying each monomial separately. Our main error bounds depend primarily on the degree of the monomial, making them easy to compute. Since monomial convexification studies depend on the bounds on the associated variables, in the second part, we conduct an error analysis for a multilinear monomial over two different types of box constraints. As part of this analysis, we also derive the convex hull of a multilinear monomial over $[-1,1]^n$.
description: 33 pages, 2 figures, to appear in journal
Smart Content Recognition from Images Using a Mixture of Convolutional Neural Networks
Creators: name: Connie, Tee
name: Al-Shabi, Mundher
name: Goh, Michael
Publisher: name: arXiv
Year: 2016
Subjects: subject: Machine Learning (stat.ML)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Neural and Evolutionary Computing (cs.NE)
subject: FOS: Computer and information sciences

description: With rapid development of the Internet, web contents become huge. Most of the websites are publicly available, and anyone can access the contents from anywhere such as workplace, home and even schools. Nevertheless, not all the web contents are appropriate for all users, especially children. An example of these contents is pornography images which should be restricted to certain age group. Besides, these images are not safe for work (NSFW) in which employees should not be seen accessing such contents during work. Recently, convolutional neural networks have been successfully applied to many computer vision problems. Inspired by these successes, we propose a mixture of convolutional neural networks for adult content recognition. Unlike other works, our method is formulated on a weighted sum of multiple deep neural network models. The weights of each CNN models are expressed as a linear regression problem learned using Ordinary Least Squares (OLS). Experimental results demonstrate that the proposed model outperforms both single CNN model and the average sum of CNN models in adult content recognition.
description: To be published in LNEE, Code: github.com/mundher/NSFW
The Turkey-Libya Memorandum of Understanding: “cutting-off” the very essence of international law
Creators: name: Tsitilakou, Michaela
name: Τσιτιλάκου, Μιχαέλα
Publisher: name: Πανεπιστήμιο Πειραιώς
Year: 2021
Subjects: subject: International law
subject: UNCLOS
subject: VCLT
subject: State responsibility
subject: Turkey
subject: Libya
subject: Greece
subject: MoU
subject: Sovereign rights
subject: Continental shelf
subject: Maritime delimitation
subject: The Principle of Permanent Sovereignty over natural resources
subject: The right to self-determination of peoples
subject: Jus cogens
subject: Article 53 of the VCLT
subject: Annulment
subject: Wrongful Act
subject: Reparation

description: Σε μία εποχή σοβαρών γεωπολιτικών ανακατατάξεων, η διεθνής έννομη τάξη αντιμετωπίζει προκλήσεις, οι οποίες καθιστούν επιτακτική την ανάγκη τροποποιήσεων, προκειμένου να διασφαλιστεί η ασφάλεια δικαίου και η σταθερότητα σε ένα δίκαιο διεθνές περιβάλλον, το οποίο θα πρέπει να διαθέτει τα μέσα νομικής επιβολής και παρέμβασης, ιδίως σε περιπτώσεις παραβίασης κανόνων που έχουν τεθεί για την εξυπηρέτηση και την προστασία του δημόσιου συμφέροντος. Η παρούσα μεταπτυχιακή διατριβή, εξετάζει την υπόθεση του Μνημονίου Κατανόησης που υπεγράφη μεταξύ των κρατών της Τουρκίας και της Λιβύης στις 27 Νοεμβρίου 2019, με σκοπό την οριοθέτηση των υποτιθέμενων θαλάσσιων συνόρων τους και τα νομικά ζητήματα που απορρέουν από το περιεχόμενο της εν λόγω συμφωνίας. Στο πλαίσιο μιας ολοκληρωμένης μελέτης επί της συγκεκριμένης υπόθεσης οριοθέτησης θαλασσίων ορίων, είναι αναγκαίο να εξεταστούν η διασύνδεση του Διεθνούς Δικαίου της Θάλασσας με το Διεθνές Δίκαιο, οι δικαιοδοτικές θαλάσσιες ζώνες και το νομικό καθεστώς που τις διέπει δυνάμει της Συνθήκης του Δικαίου της θάλασσας, με κύριο σημείο ενδιαφέροντος την Υφαλοκρηπίδα, η οριοθέτηση των θαλάσσιων συνόρων ως διαδικασία, καθώς και οι απορρέουσες επιπτώσεις από την εμπλοκή εξαρτημένων νησιών στο μέσον αυτής, και η νομική φύση του εν λόγω Μνημονίου Συνεννόησης, η οποία είναι καθοριστική για την εφαρμογή του Διεθνούς Δικαίου, του Δικαίου των Συνθηκών και της διεθνούς ευθύνης των κρατών. Στόχοι της παρούσας έρευνας είναι η παροχή τεκμηρίων αναφορικά με την παράνομη φύση του Μνημονίου Κατανόησης, ο εντοπισμός όλων των πιθανών παραβιάσεων που έχουν λάβει χώρα, καθώς και ο προσδιορισμός των έννομων συνεπειών του, των πιθανών λόγων ακυρότητας και των προβλεπόμενων διαδικασιών για την ακύρωσή του, μαζί με τα θεμελιωμένα δικαιώματα των ζημιωθέντων τρίτων κρατών, στο πλαίσιο του Διεθνούς Δικαίου.
Adiabatic self-consistent collective path in nuclear fusion reactions
Creators: name: Wen, Kai
name: Nakatsukasa, Takashi
Publisher: name: arXiv
Year: 2017
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Collective reaction paths for fusion reactions, $^{16}$O+$α$ $\rightarrow$ $^{20}$Ne and $^{16}$O+$^{16}$O $\rightarrow$ $^{32}$S, are microscopically determined, on the basis of the adiabatic self-consistent collective coordinate (ASCC) method. The collective path is maximally decoupled from other intrinsic degrees of freedom. The reaction paths turn out to deviate from those obtained with standard mean-field calculations with constraints on quadrupole and octupole moments. The potentials and inertial masses defined in the ASCC method are calculated along the reaction paths. The sub-barrier fusion cross sections are calculated for these systems. Inertial mass inside the Coulomb barrier may have a significant influence on the fusion cross section at the deep sub-barrier energy.
description: 11 pages, 11 figures
Joint Transmit and Receive Filter Optimization for Sub-Nyquist Delay-Doppler Estimation
Creators: name: Lenz, Andreas
name: Stein, Manuel S.
name: Swindlehurst, A. Lee
Publisher: name: arXiv
Year: 2017
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences
subject: G.3

description: In this article, a framework is presented for the joint optimization of the analog transmit and receive filter with respect to a parameter estimation problem. At the receiver, conventional signal processing systems restrict the two-sided bandwidth of the analog pre-filter $B$ to the rate of the analog-to-digital converter $f_s$ to comply with the well-known Nyquist-Shannon sampling theorem. In contrast, here we consider a transceiver that by design violates the common paradigm $B\leq f_s$. To this end, at the receiver, we allow for a higher pre-filter bandwidth $B>f_s$ and study the achievable parameter estimation accuracy under a fixed sampling rate when the transmit and receive filter are jointly optimized with respect to the Bayesian Cramér-Rao lower bound. For the case of delay-Doppler estimation, we propose to approximate the required Fisher information matrix and solve the transceiver design problem by an alternating optimization algorithm. The presented approach allows us to explore the Pareto-optimal region spanned by transmit and receive filters which are favorable under a weighted mean squared error criterion. We also discuss the computational complexity of the obtained transceiver design by visualizing the resulting ambiguity function. Finally, we verify the performance of the optimized designs by Monte-Carlo simulations of a likelihood-based estimator.
description: 15 pages, 16 figures
Molecular kinetic analysis of a local equilibrium Carnot cycle
Creators: name: Izumida, Yuki
name: Okuda, Koji
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We identify a velocity distribution function of ideal gas particles that is compatible with the local equilibrium assumption and the fundamental thermodynamic relation satisfying the endoreversibility. We find that this distribution is a Maxwell--Boltzmann distribution with a spatially uniform temperature and a spatially varying local center-of-mass velocity. We construct the local equilibrium Carnot cycle of an ideal gas, based on this distribution, and show that the efficiency of the present cycle is given by the endoreversible Carnot efficiency using the molecular kinetic temperatures of the gas. We also obtain an analytic expression of the efficiency at maximum power of our cycle under a small temperature difference. Our theory is also confirmed by a molecular dynamics simulation.
description: 9 pages, 5 figures
Quantifying the impact of mergers on the angular momentum of simulated galaxies
Creators: name: Lagos, Claudia del P.
name: Stevens, Adam R. H.
name: Bower, Richard G.
name: Davis, Timothy A.
name: Contreras, Sergio
name: Padilla, Nelson D.
name: Obreschkow, Danail
name: Croton, Darren
name: Trayford, James W.
name: Welker, Charlotte
name: Theuns, Tom
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We use EAGLE to quantify the effect galaxy mergers have on the stellar specific angular momentum of galaxies, $j_{\rm stars}$. We split mergers into: dry (gas-poor)/wet (gas-rich), major/minor, and different spin alignments and orbital parameters. Wet (dry) mergers have an average neutral gas-to-stellar mass ratio of $1.1$ ($0.02$), while major (minor) mergers are those with stellar mass ratios $\ge 0.3$ ($0.1-0.3$). We correlate the positions of galaxies in the $j_{\rm stars}$-stellar mass plane at $z=0$ with their merger history, and find that galaxies of low spins suffered dry mergers, while galaxies of normal/high spins suffered predominantly wet mergers, if any. The radial $j_{\rm stars}$ profiles of galaxies that went through dry mergers are deficient by $\approx 0.3$~dex at $r\lesssim 10\,r_{50}$ (with $r_{50}$ being the half-stellar mass radius), compared to galaxies that went through wet mergers. Studying the merger remnants reveals that dry mergers reduce $j_{\rm stars}$ by $\approx 30$\%, while wet mergers increase it by $\approx 10$\%, on average. The latter is connected to the build-up of the bulge by newly formed stars of high rotational speed. Moving from minor to major mergers accentuates these effects. When the spin vectors of the galaxies prior to the dry merger are misaligned, $j_{\rm stars}$ decreases to a greater magnitude, while in wet mergers co-rotation and high orbital angular momentum efficiently spun-up galaxies. We predict what would be the observational signatures in the $j_{\rm stars}$ profiles driven by dry mergers: (i) shallow radial profiles and (ii) profiles that rise beyond $\approx 10\,r_{50}$, both of which are significantly different from spiral galaxies.
description: Accepted for publication in MNRAS. Compared to previous revision, Fig. 6 and A1 are new, and section 3.3 was shortened
Symbolic Music Representations for Classification Tasks: A Systematic Evaluation
Creators: name: Zhang, Huan
name: Karystinaios, Emmanouil
name: Dixon, Simon
name: Widmer, Gerhard
name: Cancino-Chacón, Carlos Eduardo
Publisher: name: arXiv
Year: 2023
Subjects: subject: Audio and Speech Processing (eess.AS)
subject: Multimedia (cs.MM)
subject: Sound (cs.SD)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: Music Information Retrieval (MIR) has seen a recent surge in deep learning-based approaches, which often involve encoding symbolic music (i.e., music represented in terms of discrete note events) in an image-like or language like fashion. However, symbolic music is neither an image nor a sentence, and research in the symbolic domain lacks a comprehensive overview of the different available representations. In this paper, we investigate matrix (piano roll), sequence, and graph representations and their corresponding neural architectures, in combination with symbolic scores and performances on three piece-level classification tasks. We also introduce a novel graph representation for symbolic performances and explore the capability of graph representations in global classification tasks. Our systematic evaluation shows advantages and limitations of each input representation. Our results suggest that the graph representation, as the newest and least explored among the three approaches, exhibits promising performance, while being more light-weight in training.
description: To be published in the Proceedings of the 24th International Society for Music Information Retrieval Conference (ISMIR 2023), Milan, Italy
title: Γυναικείο φύλο και διευθυντικές θέσεις στην εκπαίδευση
title: Female gender and management positions in education
titleType: AlternativeTitle
Creators: name: Τζώρα, Νικολέττα
Publisher: name: Πανεπιστήμιο Δυτικής Αττικής
Year: 2023
Subjects: Εκπαιδευτική ηγεσία
Γυναικεία ηγεσία
Έμφυλες ανισότητες
Έμφυλες διακρίσεις
Glass ceiling
Σχολική ηγεσία

description: Το θέμα της γυναικείας εκπροσώπησης σε ανώτερες διοικητικές θέσεις στην εκπαίδευση έχει απασχολήσει εκτενώς τους θεωρητικούς , οι οποίοι επικεντρώνονται στις έμφυλες ανισότητες αλλά και στις διακρίσεις που υπάρχουν στις σημερινές κοινωνίες. Η παρούσα εργασία επιχειρεί να αναδείξει μέσα από τη βιβλιογραφική ανασκόπηση το ζήτημα της ανέλιξης των γυναικών εκπαιδευτικών στη διοικητική ιεραρχία ,τους παράγοντες εκείνους που επηρεάζουν είτε θετικά, είτε αρνητικά την κατάκτηση θέσεων ευθύνης από γυναίκες εκπαιδευτικούς και να φανεί η τυχόν αλλαγή στάσεων και ποσοστών πάνω σε αυτό το ζήτημα. Αναλυτικότερα γίνεται παρουσίαση των συναφών θεωρητικών παραδοχών και ευρημάτων, έτσι ώστε να προκύψει μια διαυγής εικόνα του προβληματισμού που έχει αναπτυχθεί. Παράλληλα, γίνεται αποτύπωση του φαινομένου της ‘γυάλινης οροφής’, το οποίο δείχνει τα εμπόδια τα οποία αντιμετωπίζουν οι γυναίκες στην προσπάθειά τους να κατακτήσουν μια διευθυντική θέση στην εκπαίδευση. Η εργασία ολοκληρώνεται με την παράθεση στοιχείων ερευνών σχετικά με την εκπαιδευτική ηγεσία του γυναικείου φύλου σε ευρωπαϊκό επίπεδο αλλά και πιο συγκεκριμένα στην Ισπανία καθώς και με σύγκριση αυτών των στοιχείων με την Ελληνική πραγματικότητα.
The anomalous decay $f_1(1285)\toργ$ and related processes
Creators: name: Osipov, A. A.
name: Pivovarov, A. A.
name: Volkov, M. K.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We work out the low-energy expansion of the anomalous $f_1(1285)\toργ$ decay amplitude by using the Nambu--Jona-Lasinio model with $U(2)\times U(2)$ chiral symmetric four-quark interactions in the one-quark-loop approximation. The related processes $f_1(1285)\toωγ$, $a_1(1260)\toωγ$, and $a_1(1260)\toργ$, are also considered. An effective meson Lagrangian responsible for $f_1ργ$, $f_1ωγ$, $a_1ργ$ and $a_1ωγ$ interactions is found. The predicted radiative decay widths, $Γ_{f_1\toρ^0γ}=311\ \mbox{keV}$, $Γ_{f_1\toωγ}=34.3\ \mbox{keV}$, $Γ_{a_1\toρ^0γ}=26.8\ \mbox{keV}$, $Γ_{a_1\toωγ}=238\ \mbox{keV}$, allow an experimental test of the hypothesis that $f_1(1285)$ and $a_1(1260)$-mesons have a quark-antiquark nature. At present, only the $f_1(1285)\toργ$ decay has been measured. Our result is in remarkably good agreement with the recent data of CLAS Collaboration $Γ_{f_1\toρ^0γ}=453\pm 177\ \mbox{keV}$, but disagrees with the PDG-based estimate of $Γ_{f_1\toρ^0γ}=1326\pm 313\ \mbox{keV}$. The calculations presented require a minimum of theoretical input, and are shown to be consistent with the non-renormalization theorems of QCD.
description: 7 pages, 1 figure, appear in Physical Review D
A complete catalogue of merger fractions in AGN hosts: No evidence for an increase in detected merger fraction with AGN luminosity
Creators: name: Villforth, C.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Despite the importance of Active Galactic Nuclei (AGN) in galaxy evolution, the mechanisms that fuel AGN activity remain poorly understood. Theoretical models suggest that major mergers of galaxies contribute strongly to AGN fuelling, particularly at high AGN luminosities. The connection between mergers and AGN activity has therefore been widely studied, although with contradictory results. Some studies find a strong connection between mergers and AGN, while others find merger fractions in AGN hosts to match those in the inactive galaxy population. To address these apparent contradictions, I present a complete and systematic analysis of detected merger fractions in AGN hosts from the literature. I assess if discrepancies between studies are indicative of systematic uncertainties and biases and analyse the detected merger fraction as a function of luminosity, redshift, and AGN selection method. X-ray selected AGN samples show comparable detected merger fractions across studies and major mergers do not dominate triggering in this AGN population. On the other hand, signatures of significant merger contribution to the AGN population are observed in a small fraction of primarily radio selected and reddened AGN samples. It is unclear if this is due to observational biases or physical differences in the host galaxies. There is no correlation between the detected merger fraction and AGN luminosity. This lack of correlation between detected merger fraction and AGN luminosity, which has previously been reported in the literature, cannot be explained by systematic uncertainties and observational biases.
description: accepted for publication in The Open Journal of Astrophysics
Magnetic order in the $S_{\mathrm{eff}}$ = 1/2 triangular-lattice compound NdCd$_3$P$_3$
Creators: name: Chamorro, Juan R.
name: Jackson, Azzedin R.
name: Watkins, Aurland K.
name: Seshadri, Ram
name: Wilson, Stephen D.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We present and characterize a new member of the $R$Cd$_3$P$_3$ ($R$= rare earth) family of materials, NdCd$_3$P$_3$, which possesses Nd$^{3+}$ cations arranged on well-separated triangular lattice layers. Magnetic susceptibility and heat capacity measurements demonstrate a likely $S_{\mathrm{eff}}$ = 1/2 ground state, and also reveal the formation of long-range antiferromagnetic order at $T_{N} = 0.34$ K. Via measurements of magnetization, heat capacity, and electrical resistivity, we characterize the electronic properties of NdCd$_3$P$_3$ and compare results to density functional theory calculations.
description: Accepted for publication at Physical Review Materials
Fast-slow asymptotic for semi-analytical ignition criteria in FitzHugh-Nagumo system
Creators: name: Bezekci, B.
name: Biktashev, V. N.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We study the problem of initiation of excitation waves in the FitzHugh-Nagumo model. Our approach follows earlier works and is based on the idea of approximating the boundary between basins of attraction of propagating waves and of the resting state as the stable manifold of a critical solution. Here, we obtain analytical expressions for the essential ingredients of the theory by singular perturbation using two small parameters, the separation of time scales of the activator and inhibitor, and the threshold in the activator's kinetics. This results in a closed analytical expression for the strength-duration curve.
description: 10 pages, 5 figures, as accepted to Chaos on 2017/06/26
Subtracting IR Renormalons from Wilson Coefficients: Uniqueness and power dependences on $Λ_\mathrm{QCD}$
Creators: name: Mishima, Go
name: Sumino, Yukinari
name: Takaura, Hiromasa
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: In the context of OPE and using the large-$β_0$ approximation, we propose a method to define Wilson coefficients free from uncertainties due to IR renormalons. We first introduce a general observable $X(Q^2)$ with an explicit IR cutoff, and then we extract a genuine UV contribution $X_\mathrm{UV}$ as a cutoff-independent part. $X_\mathrm{UV}$ includes power corrections $\sim (Λ_\mathrm{QCD}^2/Q^2)^n$ which are independent of renormalons. Using the integration-by-regions method, we observe that $X_\mathrm{UV}$ coincides with the leading Wilson coefficient in OPE and also clarify that the power corrections originate from UV region. We examine scheme dependence of $X_\mathrm{UV}$ and single out a specific scheme favorable in terms of analytical properties. Our method would be optimal with respect to systematicity, analyticity and stability. We test our formulation with the examples of the Adler function, QCD force between $Q \bar{Q}$, and $R$-ratio in $e^{+} e^{-}$ collision.
description: 55 pages, 11 figures, 1 table. v3: version published in PRD
Sensing Floquet-Majorana fermions via heat transfer
Creators: name: Molignini, Paolo
name: van Nieuwenburg, Evert
name: Chitra, R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Time periodic modulations of the transverse field in the closed XY spin-1/2 chain generate a very rich dynamical phase diagram, with a hierarchy of topological phases characterized by differing numbers of Floquet-Majorana modes. We show that this rich phase diagram survives when the system is coupled to dissipative end reservoirs. Circumventing the obstacle of preparing and measuring quasi energy configurations endemic to Floquet-Majorana detection schemes, we show that stroboscopic heat transport and spin density are robust observables to detect both the dynamical phase transitions and Majorana modes. In particular, we find that the derivative of the heat current, with respect to a control parameter, changes sign at the boundaries separating topological phases with different numbers of Floquet Majorana modes. We present a simple scheme to directly count the number of Floquet-Majorana modes in a phase from the Fourier transform of the local spin density profile. Our results are valid provided the anisotropies are not strong and can be easily implemented in quantum engineered systems.
description: 5 pages, 3 figures
The number of convex tilings of the sphere by triangles, squares, or hexagons
Creators: name: Engel, Philip
name: Smillie, Peter
Publisher: name: arXiv
Year: 2017
Subjects: subject: Geometric Topology (math.GT)
subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 53C45, 32G15

description: A tiling of the sphere by triangles, squares, or hexagons is convex if every vertex has at most 6, 4, or 3 polygons adjacent to it, respectively. Assigning an appropriate weight to any tiling, our main result is explicit formulas for the weighted number of convex tilings with a given number of tiles. To prove these formulas, we build on work of Thurston, who showed that the convex triangulations correspond to orbits of vectors of positive norm in a Hermitian lattice $Λ\subset \mathbb{C}^{1,9}$. First, we extend this result to convex square- and hexagon-tilings. Then, we explicitly compute the relevant lattice $Λ$. Next, we integrate the Siegel theta function for $Λ$ to produce a modular form whose Fourier coefficients encode the weighted number of tilings. Finally, we determine the formulas using finite-dimensionality of spaces of modular forms.
description: 23 pages, 6 figures
Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopy
Creators: name: Battisti, Irene
name: Fedoseev, Vitaliy
name: Bastiaans, Koen M.
name: de la Torre, Alberto
name: Perry, Robin S.
name: Baumberger, Felix
name: Allan, Milan P.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The effective Mott gap measured by scanning tunneling microscopy (STM) in the lightly doped Mott insulator $(\rm{Sr}_{1 -x}\rm{La}_x)_2\rm{IrO}_4$ differs greatly from values reported by photoemission and optical experiments. Here, we show that this is a consequence of the poor electronic screening of the tip-induced electric field in this material. Such effects are well known from STM experiments on semiconductors, and go under the name of tip-induced band bending (TIBB). We show that this phenomenon also exists in the lightly doped Mott insulator $(\rm{Sr}_{1 -x}\rm{La}_x)_2\rm{IrO}_4$ and that, at doping concentrations of $x\leq 4 \%$, it causes the measured energy gap in the sample density of states to be bigger than the one measured with other techniques. We develop a model able to retrieve the intrinsic energy gap leading to a value which is in rough agreement with other experiments, bridging the apparent contradiction. At doping $x \approx 5 \%$ we further observe circular features in the conductance layers that point to the emergence of a significant density of free carriers in this doping range, and to the presence of a small concentration of donor atoms. We illustrate the importance of considering the presence of TIBB when doing STM experiments on correlated-electron systems and discuss the similarities and differences between STM measurements on semiconductors and lightly doped Mott insulators.
description: 9 pages, 5 figures
K3-fibered Calabi-Yau threefolds I, the twist map
Creators: name: Hunt, Bruce
name: Schimmrigk, Rolf
Publisher: name: arXiv
Year: 1999
Subjects: subject: Algebraic Geometry (math.AG)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 14J30, 32J81

description: A construction of Calabi-Yaus as quotients of products of lower-dimensional spaces in the context of weighted hypersurfaces is discussed, including desingularisation. The construction leads to Calabi-Yaus which have a fiber structure, in particular one case has K3 surfaces as fibers. These Calabi-Yaus are of some interest in connection with Type II -heterotic string dualities in dimension 4. A section at the end of the paper summarises this for the non-expert mathematician.
description: 31 pages LaTeX, 11pt, 2 figures. To appear in International Journal of Mathematics. On the web at http://personal-homepages.mis.mpg.de/bhunt/preprints.html , #5
Effective Action for Non-Geometric Fluxes from Duality Covariant Actions
Creators: name: Lee, Kanghoon
name: Rey, Soo-Jong
name: Sakatani, Yuho
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The (heterotic) double field theories and the exceptional field theories are recently developed for manifestly duality covariant formulation of various supergravity theories, describing low-energy limit of various (heterotic) superstring and M-theory compactifications. These field theories are known to be reduced to the standard descriptions by introducing appropriately parameterized generalized metric and by applying suitably chosen section conditions. We generalize this development to non-geometric backgrounds by utilizing dual fields pertinent to non-geometric fluxes. We introduce different parameterizations for the generalized metric, in terms of the conventional supergravity fields or the dual fields. Under certain simplifying assumptions, we construct new effective action for non-geometric backgrounds. We then obtain the non-geometric backgrounds sourced by exotic branes. From them, we construct their $U$-duality monodromy matrices. The charge of exotic branes obtained from these monodromy matrices agrees perfectly with the charge obtained from the non-geometric flux integral.
description: cover + 101 pages; v2. published version in JHEP