cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The ghost-antighost-gluon vertex from the Curci-Ferrari model: Two-loop corrections
Creators: name: Barrios, Nahuel
name: Peláez, Marcela
name: Reinosa, Urko
name: Wschebor, Nicolás
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The Curci-Ferrari model has been shown to provide a good grasp on pure Yang-Mills correlation functions in the Landau gauge, already at one-loop order. In a recent work, the robustness of these results has been tested by evaluating the two-loop corrections to the gluon and ghost propagators. We pursue this systematic investigation by computing the ghost-antighost-gluon vertex to the same accuracy in a particular kinematic configuration that makes the calculations simpler. Because both the parameters of the model and the normalizations of the fields have already been fixed in a previous work, the present calculation represents both a pure prediction and a stringent test of the approach. We find that the two-loop results systematically improve the comparison to Monte-Carlo simulations as compared to earlier one-loop results. The improvement is particularly significative in the SU($3$) case where the predicted ghost-antighost-gluon vertex is in very good agreement with the data. The same comparison in the SU($2$) case is not as good, however. This may be due to the presence of a larger coupling constant in the infrared in that case although we note that a similar mismatch has been quoted in non-perturbative continuum approaches. Despite these features of the SU($2$) case, it is possible to find sets of parameters fitting both the propagators and the ghost-antighost-gluon vertex to a reasonable accuracy.
description: 31 pages, 12 figures
Welsh Wreck Web Research Project (North Cardigan Bay). On-line research into the wreck of the: Lady Hincks
Creators: name: Perks, Graeme
Publisher: name: Archaeology Data Service
Year: 2024

description: Welsh Wreck Web Research Project unpublished report series, 1
description: The Lady Hincks was a composite barque built in Quebec and launched in 1871 by William Baldwin. The Lady Hincks was sailed to London and sold to H Ellis and Co before starting her numerous voyages to Ceylon and the Far East. The Lady Hincks also travelled between London and Australia with the return journey via the Columbia River in Oregon, USA, a voyage around the world. In 1875 the Lady Hinks needed extensive repairs in Australia due to damage sustained from the adverse weather. The Lady Hinks was sold in about 1880 to Hatfield and Co of Liverpool and continued voyages to Australia and British North America. In December 1883 on a voyage carrying timber from Montreal to Liverpool the Lady Hinks encountered a force 10 storm and was blown ashore and wrecked in North Wales. The crew rowed ashore safely after the local lifeboat was capsized.
Three-Dimensional Simulations of Spherical Accretion Flows with Small-Scale Magnetic Fields
Creators: name: Igumenshchev, Igor V.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Spherical (nonrotating) accretion flows with small-scale magnetic fields have been investigated using three-dimensional, time-dependent MHD simulations. These simulations have been designed to model high-resolution (quasi) steady accretion flows in a wedge computational domain that represents a small fraction of the full spherical domain. Subsonic and supersonic (super-fast-magnetosonic) accretion flows have been considered. Two accretion regimes have been studied: conservative, or radiatively inefficient, and nonconservative, in which the heat released in magnetic reconnections is completely lost. The flows in both regimes are turbulent. They show the flattened radial density profiles and reduction of the accretion velocities and mass accretion rates in comparison with hydrodynamic Bondi flows. In the conservative regime, the turbulence is more intensive and supported mostly by thermal convection. In the nonconservative regime, the turbulence is less intensive and supported by magnetic buoyancy and various magnetic interactions. We have concluded that steady, supersonic spherical accretion cannot be developed in the presence of small-scale magnetic fields.
description: 31 pages, 7 figures attached in jpg-format; to appear in ApJ
Simulation of positive streamers in CO$_2$ and in air: the role of photoionization or other electron sources
Creators: name: Bagheri, Behnaz
name: Teunissen, Jannis
name: Ebert, Ute
Publisher: name: arXiv
Year: 2020
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Positive streamer discharges have been studied and modelled extensively in air. Here we study positive streamers in CO$_2$ with and without oxygen admixtures; they are relevant for current high voltage technology as well as for discharges in the atmosphere of Venus. We discuss that no efficient photoionization mechanism is known for gases with a large CO$_2$ fraction, as photons in the relevant energy range are rapidly absorbed. Hence positive streamers can propagate only due to some other source of free electrons ahead of the ionization front. Therefore we study positive streamer propagation in CO$_2$ with different levels of background ionization to provide these free electrons. The effect of replacing photoionization by background ionization is studied with simulations in air. Simulating streamers in background fields of 16 to 20~kV/cm at standard temperature and pressure within a gap of 6.4~cm, we find that streamer propagation is rather insensitive to the level of photoionization or background ionization. We also discuss that the results depend not only on the value of breakdown field and applied electric field, and on preionization or photoionization, but also on the electron mobility $μ(E)$ and the effective ionization coefficient $α_{\rm eff}(E)$, that are gas-dependent functions of the electron energy or the electric field.
Simulation of the Magnetothermal Instability
Creators: name: Parrish, Ian J.
name: Stone, James M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: In many magnetized, dilute astrophysical plasmas, thermal conduction occurs almost exclusively parallel to magnetic field lines. In this case, the usual stability criterion for convective stability, the Schwarzschild criterion, which depends on entropy gradients, is modified. In the magnetized long mean free path regime, instability occurs for small wavenumbers when (dP/dz)(dln T/dz) > 0, which we refer to as the Balbus criterion. We refer to the convective-type instability that results as the magnetothermal instability (MTI). We use the equations of MHD with anisotropic electron heat conduction to numerically simulate the linear growth and nonlinear saturation of the MTI in plane-parallel atmospheres that are unstable according to the Balbus criterion. The linear growth rates measured from the simulations are in excellent agreement with the weak field dispersion relation. The addition of isotropic conduction, e.g. radiation, or strong magnetic fields can damp the growth of the MTI and affect the nonlinear regime. The instability saturates when the atmosphere becomes isothermal as the source of free energy is exhausted. By maintaining a fixed temperature difference between the top and bottom boundaries of the simulation domain, sustained convective turbulence can be driven. MTI-stable layers introduced by isotropic conduction are used to prevent the formation of unresolved, thermal boundary layers. We find that the largest component of the time-averaged heat flux is due to advective motions as opposed to the actual thermal conduction itself. Finally, we explore the implications of this instability for a variety of astrophysical systems, such as neutron stars, the hot intracluster medium of galaxy clusters, and the structure of radiatively inefficient accretion flows.
description: Accepted for publication in Astrophysics and Space Science as proceedings of the 6th High Energy Density Laboratory Astrophysics (HEDLA) Conference
Welsh Wreck Web Research Project (North Cardigan Bay). On-line research into the wreck of the: Lancaster of Liverpool
Creators: name: Perks, Graeme
Publisher: name: Archaeology Data Service
Year: 2024

description: Welsh Wreck Web Research Project unpublished report series, 1
description: The fully rigged ship the Lancaster was 353 tons and was built in Lancaster in 1813 and was armed with four 12 pounder carronades. The first owners traded with the Virgin Islands in the Caribbean in mainly sugar and cotton during the 1812-14 war with the USA. The second owners Barton, Irlam and Higginson used Lancaster for trade between Barbados and Liverpool carrying cargo's of sugar, cotton and dyes. Including Madeira in later voyages to carry wine. Lancaster lost her masts in a hurricane in 1830 but safely reached port. The Lancaster was sold to Sir John Tobin in 1832, who used Lancaster to trade from Liverpool with Africa for palm oil and ivory. On Lancaster's third voyage after sheltering in St Tudwall Roads in Cardigan bay she set sail and hit the end of St Patricks causeway( Sarn Badrig). When the tide flooded the ship broke up and later with the cargo washed ashore. Some of the cargo was saved.
The CARMENES search for exoplanets around M dwarfs: Rubidium abundances in nearby cool stars
Creators: name: Abia, C.
name: Tabernero, H. M.
name: Korotin, S. A.
name: Montes, D.
name: Marfil, E.
name: Caballero, J. A.
name: Straniero, O.
name: Prantzos, N.
name: Ribas, I.
name: Reiners, A.
name: Quirrenbach, A.
name: Amado, P. J.
name: Bejar, V. J. S.
name: Cortes-Contreras, M.
name: Dreizler, S.
name: Henning, Th.
name: Jeffers, S. V.
name: Kaminski, A.
name: Kürster, M.
name: Lafarga, M.
name: Lopez-Gallifa, A.
name: Morales, J. C.
name: Nagel, E.
name: Passegger, V. M.
name: Pedraz, S.
name: Lopez, C. Rodriguez
name: Schweitzer, A.
name: Zechmeister, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: In this study, abundances of the neutron-capture elements Rb, Sr, and Zr are derived, for the first time, in a sample of nearby M dwarfs. We focus on stars in the metallicity range -0.50.0 is attained at metallicities higher than solar. These are surprising results, never seen for any other heavy element, and are difficult to understand within the formulation of the s- and r-processes, both contributing sources to the Galactic Rb abundance. We discuss the reliability of these findings for Rb in terms of non-LTE effects, stellar activity, or an anomalous Rb abundance in the Solar System, but no explanation is found. We then interpret the full observed [Rb/Fe] versus [Fe/H] trend within the framework of theoretical predictions from state-of-the-art chemical evolution models for heavy elements, but a simple interpretation is not found either. In particular, the possible secondary behaviour of the [Rb/Fe] ratio at super-solar metallicities would require a much larger production of Rb than currently predicted in AGB stars through the s-process without overproducing Sr and Zr.
description: 16 pag, 8 Figs, 1 table. Accepted in Astronomy & Astrophysics
Dual equilibrium in a finite aspect ratio tokamak
Creators: name: Gourdain, P. -A.
name: Cowley, S. C.
name: Leboeuf, J. -N.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: A new approach to high pressure magnetically-confined plasmas is necessary to design efficient fusion devices. This paper presents an equilibrium combining two solutions of the Grad-Shafranov equation, which describes the magnetohydrodynamic equilibrium in toroidal geometry. The outer equilibrium is paramagnetic and confines the inner equilibrium, whose strong diamagnetism permits to balance large pressure gradients. The existence of both equilibria in the same volume yields a dual equilibrium structure. Their combination also improves free-boundary mode stability.
Lassie: HOL4 Tactics by Example
Creators: name: Becker, Heiko
name: Bos, Nathaniel
name: Gavran, Ivan
name: Darulova, Eva
name: Majumdar, Rupak
Publisher: name: arXiv
Year: 2021
Subjects: subject: Programming Languages (cs.PL)
subject: Logic in Computer Science (cs.LO)
subject: FOS: Computer and information sciences

description: Proof engineering efforts using interactive theorem proving have yielded several impressive projects in software systems and mathematics. A key obstacle to such efforts is the requirement that the domain expert is also an expert in the low-level details in constructing the proof in a theorem prover. In particular, the user needs to select a sequence of tactics that lead to a successful proof, a task that in general requires knowledge of the exact names and use of a large set of tactics. We present Lassie, a tactic framework for the HOL4 theorem prover that allows individual users to define their own tactic language by example and give frequently used tactics or tactic combinations easier-to-remember names. The core of Lassie is an extensible semantic parser, which allows the user to interactively extend the tactic language through a process of definitional generalization. Defining tactics in Lassie thus does not require any knowledge in implementing custom tactics, while proofs written in Lassie retain the correctness guarantees provided by the HOL4 system. We show through case studies how Lassie can be used in small and larger proofs by novice and more experienced interactive theorem prover users, and how we envision it to ease the learning curve in a HOL4 tutorial.
Analysis of a Force-Based Quasicontinuum Approximation
Creators: name: Dobson, Matthew
name: Luskin, Mitchell
Publisher: name: arXiv
Year: 2006
Subjects: subject: Numerical Analysis (math.NA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 65Z05

description: We analyze a force-based quasicontinuum approximation to a one-dimensional system of atoms that interact by a classical atomistic potential. This force-based quasicontinuum approximation is derived as the modification of an energy-based quasicontinuum approximation by the addition of nonconservative forces to correct nonphysical ``ghost'' forces that occur in the atomistic to continuum interface. We prove that the force-based quasicontinuum equations have a unique solution under suitable restrictions on the loads. For Lennard-Jones next-nearest-neighbor interactions, we show that unique solutions exist for loads in a symmetric region extending nearly to the tensile limit. We give an analysis of the convergence of the ghost force iteration method to solve the equilibrium equations for the force-based quasicontinuum approximation. We show that the ghost force iteration is a contraction and give an analysis for its convergence rate.
description: 26 pages, 7 figures
Overcoming the Rayleigh Criterion Limit with Optical Vortices
Creators: name: Tamburini, F.
name: Anzolin, G.
name: Umbriaco, G.
name: Bianchini, A.
name: Barbieri, C.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We experimentally and numerically tested the separability of two independent equally-luminous monochromatic and white light sources at the diffraction limit, using Optical Vortices (OV), related to the Orbital Angular Momentum (OAM) of light. The diffraction pattern of one of the two sources crosses a phase modifying device (fork-hologram) on its center generating the Laguerre-Gaussian (L-G) transform of an Airy disk. The second source, crossing the fork-hologram in positions different from the optical center, acquires different OAM values and generates non-symmetric L-G patterns. We formulated a criterion, based on the asymmetric intensity distribution of the superposed L-G patterns so created, to resolve the two sources at angular distances much below the Rayleigh criterion. Analogous experiments carried out in white light allow angular resolutions which are still one order of magnitude below the Rayleigh criterion. The use OVs might offer new applications for stellar separation in future space experiments.
description: 4 pages, 5 figures
Welsh Wreck Web Research Project (North Cardigan Bay). On-line research into the wreck of the: Laura Griffith
Creators: name: Perks, Graeme
Publisher: name: Archaeology Data Service
Year: 2024

description: Welsh Wreck Web Research Project unpublished report series, 1
description: The Laura Griffith official number 52522 or Griffiths as she was sometimes called was a schooner of 100 tons,76ft long and 20ft wide. She was built at Pwllheli in 1864/5 and registered at Caernarfon. The vessel was named after the landlady of the Tower Inn near where it was built. The Laura Griffith was driven onto a lee shore in a gale and broken up by the action of the sea.
Η θεωρία του Jurgen Habermas για την πολιτική και την δημοκρατία
Creators: name: Καρακίτσιου, Βασιλική Χρυσόστομου
Publisher: name: Aristotle University of Thessaloniki
Year: 2015
Subjects: Γιούργκεν Χάμπερμας
Πολιτική
Δημοκρατία
Jurgen Habermas
Politics
Democracy

description: Σκοπός της διατριβής μου ήταν η μελέτη της θεωρίας του Jurgen Habermas, όσον αφορά την πολιτική και την δημοκρατία. Εξετάσαμε την πολιτική του θεωρία, όπως αυτή διαμορφώνεται μέσω του επικοινωνιακού πράττειν και της συγκρότησης του κράτους δικαίου. Στη συνέχεια αναφερθήκαμε στα θεμελιώδη δικαιώματα, καθώς και στις βασικές αρχές που διέπουν το κράτος διακαίου. Έπειτα αναλύσαμε το μοντέλο της διαβουλευτικής δημοκρατίας, το οποίο και προασπίζεται ο Γερμανός φιλόσοφος, καθώς και όλες τις βασικές του αρχές. Ακόμη αναφερόμενοι, στο όραμα του για μια ομοσπονδιακή Ευρωπαϊκή διαβουλευτική δημοκρατία παραθέσαμε τις προοπτικές της υλοποίησής του μοντέλου αυτού. Ένα ακόμη θέμα που θίξαμε ήταν οι κριτικές που έχει δεχθεί ο φιλόσοφος για την από πολλούς αμφισβητούμενη θεωρία του και τις διαμάχες στις οποίες έχει εμπλακεί. Τέλος, αναφερθήκαμε στα συμπεράσματα και στους προβληματισμούς που μας δημιούργησε η έρευνά μας• όσον αφορά κυρίως την έντονη υπεράσπιση από τον φιλόσοφο του διαβουλευτικού μοντέλου δημοκρατίας και κατά πόσον αυτό θα μπορούσε να ευδοκιμήσει σήμερα.
description: The aim of my thesis was to study the theory of Jurgen Habermas, in terms of politics and democracy. We examined the political theory, as it is formed through the Communicative Action and the establishment of the state of justice. Then we talked to fundamental rights and the basic principles governing the state of justice Then we analyzed the model of deliberative democracy, which defends the German philosopher, and all its basic principles. Still referring to the vision of a federal European Deliberative Democracy quoted the prospects of implementation of this model. Another topic that we raised were the reviews that has received the philosopher for many controversial theory and the controversies that have been involved Finally, we discussed the conclusions and concerns created us our research; in particular on its strong defense of the philosopher of deliberative democracy model and whether this could succeed today.
Προσωπικά περιβάλλοντα μάθησης. Η αξιοποίηση τους στη γλωσσική εκπαίδευση.
Creators: name: Καρακουζίδου, Ζαχαρούλα Δημητρίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2015
Subjects: Προσωπικά περιβάλλοντα μάθησης
Ηλεκτρονική μάθηση
Γλωσσική εκπαίδευση
Personal learning environments
Web 2.0
LMS

description: Αντικείμενο της παρούσας διπλωματικής είναι Προσωπικά Περιβάλλοντα Μάθησης. Συγκεκριμένα, παρουσιάσαμε το πεδίο σε όλες του τις διαστάσεις και σχεδιάσαμε και ένα τέτοιο περιβάλλον βασισμένο επάνω στην πλατφόρμα Netvibes. Εξετάσαμε την ηλεκτρονική μάθηση και τα Συστήματα Διαχείρισης Μάθησης. Επίσης, στο ίδιο κεφάλαιο, στο πρώτο, παρουσιάστηκαν και οι θεωρίες μάθησης που μπορούν να εφαρμοστούν στο e-learning. Στη συνέχεια, παρουσιάσαμε αναλυτικά το Web 2.0 και τη περίοδο μετάβασης από το Web 1.0 στο Web 2.0. Ακόμη, αναφερθήκαμε και στο κοινωνικό λογισμικό και παρουσιάσαμε αναλυτικά τα εργαλεία του Web 2.0. Στο τρίτο κεφάλαιο, αναφερθήκαμε εκτενώς στην έννοια των Προσωπικών Περιβαλλόντων Μάθησης (PLEs). Παρουσιάστηκαν οι προσεγγίσεις όπως υπάρχουν στη βιβλιογραφία, επίσης, οι παράγοντες που οδήγησαν στην εμφάνιση των PLEs, αλλά και οι θεωρίες μάθησης που υποστηρίζουν αυτά τα περιβάλλοντα. Στο τέλος αυτού του κεφαλαίου θίγονται οι τρόποι ανάπτυξης ενός PLE. Το τελευταίο θέμα που παρουσιάσαμε ήταν ο σχεδιασμός ενός μαθησιακού περιβάλλοντος με στόχο την αξιοποίηση του στη γλωσσική εκπαίδευση. Ασχοληθήκαμε επιπλέον με την αξιοποίηση των υπηρεσιών Web 2.0 ώστε οι μαθητές να προσεγγίσουν τη γλώσσα με διαφορετικό τρόπο και διαπιστώσαμε την ελεύθερη και ευέλικτη διαδικασία με τη μέθοδο αυτή σε σχέση με τα έως τώρα συστήματα εκμάθησης e-learning.
description: The subject of this thesis is Personal Learning Environments. Specifically, we introduced the field in all its dimensions and we designed such an environment based on the Netvibes platform. We examined the e-learning and Learning Management Systems. Moreover, in the same chapter, the first, presented also the learning theories that can be applied to e-learning. Then, we introduced the Web 2.0 in detail and the transition from Web 1.0 to Web 2.0. Furthermore, we referred in social software and we presented in detail the tools of Web 2.0. In the third chapter, we discussed extensively the concept of Personal Learning Environments (PLEs). Here, there were presented the approaches as they exist in literature and also the factors behind the appearance of PLEs, and which learning theories supporting these environments. At the end of this chapter, we mentioned the ways of developing a PLE. The last subject we introduced was the design of a learning environment in order to utilize the language learning. We discussed more the further development of Web 2.0 so that it will be easier for the students to approach the language differently and founding free and flexible process with this method compared to the e-learning systems
Photospheric Velocity Gradients and Ejecta Masses of Hydrogen-poor Superluminous Supernovae -- Proxies for Distinguishing between Fast and Slow Events
Creators: name: Könyves-Tóth, Réka
name: Vinkó, József
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We present a study of 28 Type I superluminous supernovae (SLSNe) in the context of the ejecta mass and photospheric velocity. We combine photometry and spectroscopy to infer ejecta masses via the formalism of radiation diffusion equations. We show an improved method to determine the photospheric velocity by combining spectrum modeling and cross correlation techniques. We find that Type I SLSNe can be divided into two groups by their pre-maximum spectra. Members of the first group have the W-shaped absorption trough in their pre-maximum spectrum, usually identified as due to O II. This feature is absent in the spectra of supernovae in the second group, whose spectra are similar to SN~2015bn. We confirm that the pre- or near-maximum photospheric velocities correlate with the velocity gradients: faster evolving SLSNe have larger photosheric velocities around maximum. We classify the studied SLSNe into the Fast or the Slow evolving group by their estimated photosheric velocities, and find that all those objects that resemble to SN~2015bn belong to the Slow evolving class, while SLSNe showing the W-like absorption are represented in both Fast and Slow evolving groups. We estimate the ejecta masses of all objects in our sample, and obtain values in the range of 2.9 ($\pm$0.8) - 208 ($\pm$61) $M_\odot$, with a mean of $43 (\pm 12)~ M_\odot$. We conclude that Slow evolving SLSNe tend to have higher ejecta masses compared to the Fast ones. Our ejecta mass calculations suggests that SLSNe are caused by energetic explosions of very massive stars, irrespectively of the powering mechanism of the light curve.
description: 21 pages, Submitted to ApJ
An efficient and spectrally accurate numerical method for computing dynamics of rotating Bose-Einstein condensates
Creators: name: Bao, Weizhu
name: Wang, Hanquan
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: In this paper, we propose an efficient and spectrally accurate numerical method for computing the dynamics of rotating Bose-Einstein condensates (BEC) in two dimensions (2D) and 3D based on the Gross-Pitaevskii equation (GPE) with an angular momentum rotation term. By applying a time-splitting technique for decoupling the nonlinearity and properly using the alternating direction implicit (ADI) technique for the coupling in the angular momentum rotation term in the GPE, at every time step, the GPE in rotational frame is decoupled into a nonlinear ordinary differential equation (ODE) and two partial differential equations with constant coefficients. This allows us to develop new time-splitting spectral (TSSP) methods for computing the dynamics of BEC in a rotational frame.The new numerical method is explicit, unconditionally stable, and of spectral accuracy in space and second order accuracy in time. Moreover, it is time reversible and time transverse invariant, and conserves the position density in the discretized level if the GPE does. Extensive numerical results are presented to confirm the above properties of the new numerical method for rotating BEC in 2D and 3D.
description: 21 pages; 7 figures
Διαίρεση πολυωνυμικών πινάκων και εφαρμογές
Creators: name: Αραμπατζή, Ευαγγελία Αθανασίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2015
Subjects: Διαίρεση πολυωνυμικών πινάκων
Ανάπτυγμα Laurent αντιστρόφου πίνακα
Θεμελιώδεις πίνακες
Division of polynomial matrices
Laurent expansion
Fundamental matrices

description: Στην παρούσα εργασία εξετάζουμε την διαίρεση πολυωνυμικών πινάκων με την βοήθεια των θεμελιωδών πινάκων που προκύπτουν από το ανάπτυγμα Laurent του αντίστροφου πίνακα. Θα δώσουμε σταδιακά όλους τους ορισμούς και θεωρήματα για να γίνει κατανοητή, ως προς τον αναγνώστη, η μεθοδολογία. Στη συνέχεια, θα κάνουμε μια εφαρμογή για να δείξουμε πόσο σημαντικός είναι ο υπολογισμός της διαίρεσης πολυωνυμικών πινάκων στην θεωρία ελέγχου. Στο πρώτο κεφάλαιο δίνονται βασικοί ορισμοί των πινάκων, πολυωνύμων και του υπολογισμού του αντιστρόφου πίνακα και των θεμελιωδών πινάκων. Στο δεύτερο κεφάλαιο παρουσιάζουμε έναν αλγόριθμο για την διαίρεση πολυωνυμικών πινάκων, ενώ στο τρίτο κεφάλαιο κάνουμε εφαρμογή του συγκεκριμένου αλγορίθμου στον υπολογισμό ενός ελεγκτή για την σταθεροποίηση ενός συστήματος πολλών εισόδων-εξόδων. Όλα τα παραπάνω συνοδεύονται με παραδείγματα και αναλυτική μεθοδολογία.
description: In this paper we study the division of polynomial matrices. The division is performed in this terms of the fundamental matrices of the inverse of the polynomial matrix coming from its’ Laurent expansion. We give all the necessary definitions and theorems in order to have a better understanding of the methodology. The whole theory is implemented with an example from the Control Systems Theory. In the first section we present basic definitions that concern of matrices, polynomials and the calculation of the fundamental matrices of the inverse of a polynomial matrix. In the second section the division of the polynomial matrix is examined whereas in the third chapter section, an application of the division algorithm is proposed in Control Systems Theory.
Gauge Freedom in Orbital Mechanics
Creators: name: Efroimsky, Michael
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: Dynamical Systems (math.DS)
subject: Chaotic Dynamics (nlin.CD)
subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: In orbital and attitude dynamics the coordinates and the Euler angles are expressed as functions of the time and six constants called elements. Under disturbance, the constants are endowed with time dependence. The Lagrange constraint is then imposed to guarantee that the functional dependence of the perturbed velocity on the time and constants stays the same as in the undisturbed case. Constants obeying this condition are called osculating elements. The constants chosen to be canonical are called Delaunay elements, in the orbital case, or Andoyer elements, in the spin case. (As some Andoyer elements are time dependent even in the free-spin case, the role of constants is played by their initial values.) The Andoyer and Delaunay sets of elements share a feature not readily apparent: in certain cases the standard equations render them non-osculating. In orbital mechanics, elements furnished by the standard planetary equations are non-osculating when perturbations depend on velocities. To preserve osculation, the equations must be amended with extra terms that are not parts of the disturbing function. In the case of Delaunay parameterisation, these terms destroy canonicity. So under velocity-dependent disturbances, osculation and canonicity are incompatible. (Efroimsky and Goldreich 2003, 2004) Similarly, the Andoyer elements turn out to be non-osculating under angular-velocity-dependent perturbation. Amendment of only the Hamiltonian makes the equations render nonosculating elements. To make them osculating, more terms must enter the equations (and the equations will no longer be canonical). In practical calculations, is often convenient to deliberately deviate from osculation by substituting the Lagrange constraint with a condition that gives birth to a family of nonosculating elements.
description: Talk at the annual Princeton conference ``New Trends in Astrodynamics" 2005 http://www.math.princeton.edu/astrocon/
SCUBA2 High Redshift Bright Quasar Survey: Far-infrared Properties and Weak-line Features
Creators: name: Li, Qiong
name: Wang, Ran
name: Fan, Xiaohui
name: Wu, Xue-Bing
name: Jiang, Linhua
name: Banados, Eduardo
name: Venemans, Bram
name: Shao, Yali
name: Li, Jianan
name: Zhang, Yunhao
name: Zhang, Chengpeng
name: Wagg, Jeff
name: Decarli, Roberto
name: Mazzucchelli, Chiara
name: Omont, Alain
name: Bertoldi, Frank
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present a submillimetre continuum survey ('SCUBA2 High rEdshift bRight quasaR surveY', hereafter SHERRY) of 54 high redshift quasars at $5.63.5σ$). The new SHERRY detections indicate far-infrared (FIR) luminosities of $\rm 3.5\times10^{12}$ to $\rm 1.4\times10^{13}$ $L_{\odot}$, implying extreme star formation rates of 90 to 1060 $M_{\odot}$ yr$^{-1}$ in the quasar host galaxies. Compared with $z =$ 2$-$5 samples, the FIR luminous quasars ($L_{\rm FIR} > 10^{13}\,L_{\odot}$) are more rare at $z \sim 6$. The optical/near-infrared (NIR) spectra of these objects show 11% (6/54) of the sources have weak Ly$α$, emission line features, which may relate to different sub-phases of the central active galactic nuclei (AGNs). Our SCUBA2 survey confirms the trend reported in the literature that quasars with submillimeter detections tend to have weaker ultraviolet (UV) emission lines compared to quasars with nondetections. The connection between weak UV quasar line emission and bright dust continuum emission powered by massive star formation may suggest an early phase of AGN-galaxy evolution, in which the broad line region is starting to develop slowly or is shielded from the central ionization source, and has unusual properties such as weak line features or bright FIR emission.
description: 28 pages, 10 figures, published in ApJ
Ordinary and Extraordinary Hadrons
Creators: name: Jaffe, R. L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Resonances and enhancements in meson-meson scattering can be divided into two classes distinguished by their behavior as the number of colors N_c in QCD becomes large: The first are ordinary mesons that become stable as N_c goes to infinity. This class includes textbook q-bar q mesons as well as glueballs and hybrids. The second class, extraordinary mesons, are enhancements that disappear as N_c goes to infinity; they subside into the hadronic continuum. This class includes indistinct and controversial objects that have been classified as q-bar q-bar q q mesons or meson-meson molecules. Pelaez's study of the N_c dependence of unitarized chiral dynamics illustrates both classes: the p-wave pi-pi and K-pi resonances, the rho(770) and K*(892), behave as ordinary mesons; the s-wave pi-pi and K-pi enhancements, the sigma(600) and kappa(800), behave like extraordinary mesons. Ordinary mesons resemble Feshbach resonances while extraordinary mesons look more like effects due to potentials in meson-meson scattering channels. I build and explore toy models along these lines. Finally I discuss some related dynamical issues affecting the interpretation of extraordinary mesons.
description: 18 pages, 10 figures, talk presented at the 2006 Yukawa International Seminar: New Frontiers in QCD, Kyoto University, November 2006. This talk is dedicated to the memory of R. H. Dalitz
Waterfowl farmland use in Delta, British Columbia : a remote sensing / GIS analysis
Creators: name: Mayoral, Celia Sánchez.
Publisher: name: University of British Columbia
Year: 2009

description: Farmfields located in the vicinity of wetlands are often visited by wintering waterfowl. The selection of individual fields could be affected by a number of factors, including the crop cover type and the accumulation of surface water on the field, as well as by other factors related to the location of the field. This research investigated the possible relation between locational factors (size and shape of the field, distance to the coast, presence of trees, roads and buildings in the surroundings) and the observed presence/absence of ducks (mallard, Anas platyrynchos, pintail, Anas acuta, wigeon, Anas americana) in a group of fields in the Fraser River delta. Maps of the fields were obtained by interpretation of aerial photographs. Bird data came from previous surveys. Maps and associated attribute data were integrated in a Geographic Information System that also provided analysis tools. Regression analysis was undertaken in order to relate the presence of ducks in the fields with the geographic (locational) factors. Day and night situations were considered, and fields were grouped into two cover type classes for the analysis. Results of the analysis indicated that the consideration of just locational variables could not predict the presence of ducks in fields, although some factors, particularly the distance to the coast and the vegetation in the perimeter were found to be correlated with duck presence.
Interacting Bose and Fermi gases in low dimensions and the Riemann hypothesis
Creators: name: LeClair, André
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mathematical Physics (math-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: Number Theory (math.NT)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We apply the S-matrix based finite temperature formalism to non-relativistic Bose and Fermi gases in 1+1 and 2+1 dimensions. In the 2+1 dimensional case, the free energy is given in terms of Roger's dilogarithm in a way analagous to the relativistic 1+1 dimensional case. The 1d fermionic case with a quasi-periodic 2-body potential provides a physical framework for understanding the Riemann hypothesis.
description: version 3: additional appendix explains how the $\nu$ to $1-\nu$ duality of Riemann's $\zeta (\nu)$ follows from a special modular transformation in a massless relativistic theory
The Empirical Under-determination Argument Against Scientific Realism for Dual Theories
Creators: name: De Haro, Sebastian
Publisher: name: arXiv
Year: 2021
Subjects: subject: History and Philosophy of Physics (physics.hist-ph)
subject: FOS: Physical sciences

description: This paper explores the options available to the anti-realist to defend a Quinean empirical under-determination thesis using examples of dualities. I first explicate a version of the empirical under-determination thesis that can be brought to bear on theories of contemporary physics. Then I identify a class of examples of dualities that lead to empirical under-determination. But I argue that the resulting under-determination is benign, and is not a threat to a cautious scientific realism. Thus dualities are not new ammunition for the anti-realist. The paper also shows how the number of possible interpretative options about dualities that have been considered in the literature can be reduced, and suggests a general approach to scientific realism that one may take dualities to favour.
description: 31 pages, 3 figures
Welsh Wreck Web Research Project (North Cardigan Bay). On-line research into the wreck of the: Leander of Bath
Creators: name: Perks, Graeme
Publisher: name: Archaeology Data Service
Year: 2024

description: Welsh Wreck Web Research Project unpublished report series, 1
description: The Leander was a fully rigged ship built in Bath, Maine, USA in 1857 by E and A Sewall and used by them for transatlantic voyages. The Leander was on the return leg of her second voyage for New Orleans when she was in collision with the steamer North American in the Irish sea and sank. The owners of the Leander took an action for damages to the Admiralty Court and were successful, including on appeal. The wife of master of the Leander was drowned with nine members of crew when the Leander sank.
Image-based underwater 3D reconstruction for Cultural Heritage: from image collection to 3D. Critical steps and considerations
Creators: name: Skarlatos, Dimitrios
name: Agrafiotis, Panagiotis
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Underwater Cultural Heritage (CH) sites are widely spread; from ruins in coastlines up to shipwrecks in deep. The documentation and preservation of this heritage is an obligation of the mankind, dictated also by the international treaties like the Convention on the Protection of the Underwater Cultural Her-itage which fosters the use of "non-destructive techniques and survey meth-ods in preference over the recovery of objects". However, submerged CH lacks in protection and monitoring in regards to the land CH and nowadays recording and documenting, for digital preservation as well as dissemination through VR to wide public, is of most importance. At the same time, it is most difficult to document it, due to inherent restrictions posed by the environ-ment. In order to create high detailed textured 3D models, optical sensors and photogrammetric techniques seems to be the best solution. This chapter dis-cusses critical aspects of all phases of image based underwater 3D reconstruc-tion process, from data acquisition and data preparation using colour restora-tion and colour enhancement algorithms to Structure from Motion (SfM) and Multi-View Stereo (MVS) techniques to produce an accurate, precise and complete 3D model for a number of applications.
description: Pre-submission version of the manuscript
Η σύμβαση οργανωμένου ταξιδίου κατά το ΠΔ 339/1996
Creators: name: Βρίκος, Χρήστος Ευάγγελου
Publisher: name: Aristotle University of Thessaloniki
Year: 2015
Subjects: Οργανωμένο ταξίδι
ΠΔ 339/1996
Presidential Decree 339/1996
Package Travel
Package Tours

description: Τα όργανα της Ε.Ε έχουν κατ’ επανάληψη αναγνωρίσει το σημαντικό ρόλο του τουρισμού για την οικονομική ανάπτυξη των κρατών–μελών, με ιδιαίτερη σημασία να αποδίδεται στον ρόλο των οργανωμένων ταξιδίων που αποτελούν ίσως, το ουσιωδέστερο τμήμα της τουριστικής δραστηριότητας. Στην προσπάθεια να υπάρξει νομική ενότητα και ισορροπία στην εσωτερική αγορά αλλά και η προστασία του ταξιδιώτη ως καταναλωτή, εκδόθηκε η Οδηγία 90/314/ΕΟΚ «για τα οργανωμένα ταξίδια και τις οργανωμένες διακοπές και περιηγήσεις». Στο περιθώριο αυτό ο Έλληνας νομοθέτης, κατά συνήθη πρακτική, μετέφερε σχεδόν αυτούσιο το περιεχόμενο της Οδηγίας στο εθνικό δίκαιο με το ΠΔ. 339/1996, για το οποίο γίνεται αναλυτικά λόγος στο κύριο μέρος της παρούσης τόσο στις επί μέρους διατάξεις του όσο και σε σχέση με τον Ν.2251/1994 περί προστασίας του Καταναλωτή.Τα τελευταία χρόνια έχει κατατεθεί και νέα πρόταση Οδηγίας για διαβούλευση που έχει ως σκοπό την μετέπειτα κατάργηση της Οδηγίας 90/314/ΕΟΚ. Θεωρείται ότι η έκδοση μιας νέας οδηγίας πληρέστερης και ορθότερα προσαρμοσμένης στις εξελίξεις της αγοράς , θα δώσει περαιτέρω ώθηση ώστε να αρθούν ασάφειες και να καλυφθούν νομοθετικά κενά που υπήρχαν μέχρι και σήμερα, με απώτερο στόχο την πληρέστερη προστασία του καταναλωτή αλλά και την ορθότερη λειτουργία του ανταγωνισμού στο πλαίσιο της εσωτερικής αγοράς.
description: The institutions of the EU have repeatedly acknowledged the important role of tourism for the economic development of member states, with particular importance attaching to the role of organized trips which are perhaps the most essential part of tourism activity. In trying to achieve legal unity and balance in the internal market and the protection of the traveler as a consumer, Directive 90/314 / EEC was issued regulating "package travel, package holidays and package tours". In this framework, the Greek legislature, as usual, implemented almost unchanged the content of the Directive into national law by Presidential Decree 339/1996, which is the main part of this thesis, as far as the individual provisions and the relation to Law 2251/1994 on the Protection of Consumers is concerned. In recent years, a new Directive proposal is filled for public consultation in order to replace Directive 90/314 / EEC. It is considered that a new directive more sufficient and more appropriately adapted to market developments will give further impetus to remove ambiguities and to fill legislative gaps that existed until today, with a view to better consumer protection and better functioning of competition within the internal market .
Combinatorial entropy behaviour leads to range selective binding in ligand-receptor interactions
Creators: name: Liu, Meng
name: Apriceno, Azzurra
name: Sipin, Miguel
name: Scarpa, Edoardo
name: Rodriguez-Arco, Laura
name: Poma, Alessandro
name: Marchello, Gabriele
name: Battaglia, Giuseppe
name: Angioletti-Uberti, Stefano
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Physical sciences

description: From viruses to nanoparticles, constructs functionalized with multiple ligands display peculiar binding properties that only arise from multivalent effects. Using statistical mechanical modelling, we describe here how multivalency can be exploited to achieve what we dub range selectivity, that is, binding only to targets bearing a number of receptors within a specified range. We use our model to characterise the region in parameter space where one can expect range selective targeting to occur, and provide experimental support for this phenomenon. Overall, range selectivity represents a potential path to increase the targeting selectivity of multivalent constructs.
description: Published in Nature Communications. Received: 25 September 2019; Accepted: 28 August 2020; Link to online open-access publisher version: https://www.nature.com/articles/s41467-020-18603-5#citeas
Long Term Economic Relationships From Cointegration Maps
Creators: name: Vicente, Renato
name: Pereira, Carlos de B.
name: Leite, Vitor B. P.
name: Caticha, Nestor
Publisher: name: arXiv
Year: 2007
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Statistical Finance (q-fin.ST)
subject: FOS: Physical sciences
subject: FOS: Economics and business

description: We employ the Bayesian framework to define a cointegration measure aimed to represent long term relationships between time series. For visualization of these relationships we introduce a dissimilarity matrix and a map based on the Sorting Points Into Neighborhoods (SPIN) technique, which has been previously used to analyze large data sets from DNA arrays. We exemplify the technique in three data sets: US interest rates, monthly inflation rates and gross domestic product growth rates.
description: 13 pages, 8 figures, extended version submitted to Physica A
Welsh Wreck Web Research Project (North Cardigan Bay). On-line research into the Wrecking of Leander (Schooner)
Creators: name: Davies, Gareth J.S.
Publisher: name: Archaeology Data Service
Year: 2024

description: Welsh Wreck Web Research Project unpublished report series, 1
description: This project is to discover information relating to the history of the schooner Leander (MADU Ref 363), built and launched at Llansantffraid, Cardigan Wales in March 1859. The Leander was a cargo schooner which sailed between ports in S and N Wales, Ireland, N. Ireland, Scotland, S, SW, coasts of England, France and Belgium. Cargoes carried included raw materials and probably, grains, food products. On Nov 19th 1906, the Leander was driven ashore and wrecked 1 mile south of New Quay Cardiganshire on Traeth Gwyn Beach. The crew were picked up prior to the grounding by the New Quay Lifeboat.
A comprehensive study on the variation phenomena of AO 0235+164
Creators: name: Wang, Yifan
name: Jiang, Yunguo
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The variation mechanism of blazars is a long standing open question. The polarization observation can provide us with more information to constrain models. In this work, we collect the long term multi-wavelength data of AO 0235+164, and make correlation analysis between them by using the local cross-correlation function (LCCF). We found that both $γ$-ray and the optical {\it V}-band light curves are correlated with the radio light curve at beyond 3$σ$ significance level. The emitting regions of the $γ$-ray and the optical coincide within errors, and locate at {$6.6_{-1.7}^{+0.6}$} pc upstream of the core region of 15 GHz, which are beyond the broad line region (BLR). The color index shows the redder when brighter (RWB) trend at the low flux state, but turns to the bluer when brighter (BWB) trend at the high flux state. While, the $γ$-ray spectral index always shows the softer when brighter (SWB) trend. We propose that such complex variation trends can be explained by the increasing jet component with two constant components. The {optical} PD flares and {optical} flux flares are not synchronous. It seems that one flux peak are sandwiched by two PD peaks, which have inverse rotation trajectories in the $qu$ plane. The helical jet model can schematically show these characteristics of polarization with fine tuned parameters. The change of viewing angle is suggested to be the primary variable which lead all these variations, although other possibilities like the shock in jet model or the hadronic model are not excluded completely.
description: 11 pages, 12 figures, accepted in ApJ