cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Η εμπειρία των γονέων νεογνών που διαγνώστηκαν με σοβαρή απεικονιστική νευρολογική βλάβη και πρόγνωση σε Μονάδα Εντατικής Νοσηλείας Νεογνών
Creators: name: Πιλτσούλη, Δήμητρα Αθανασίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2020
Subjects: Νεογνά
Νευρολογική Βλάβη
Μονάδα Εντατικής Νοσηλείας Νεγνών
Neonates
Neurological Impairment
Neonatal Intensive Care unit

description: Σκοπός της μεταπτυχιακής εργασίας ήταν η μελέτη των εμπειριών και συναισθημάτων των γονέων των οποίων τα νεογνά διαγνώστηκαν με σοβαρή απεικονιστική βλάβη και πρόγνωση, ενώ νοσηλευόταν σε Μονάδα Εντατικής Νοσηλείας Νεογνών. Για το σκοπό αυτό διενεργήθηκε αναδρομική περιγραφική ποιοτική μελέτη που στηρίχτηκε στις αρχές της φαινομενολογίας. Έγινε ανάλυση περιεχομένου των αφηγήσεων των γονιών που συμμετείχαν στην έρευνα. Τα αποτελέσματα κωδικοποιήθηκαν σε πέντε κύριες κατηγορίες που είναι, το αρχικό σοκ, ενημέρωση και πληροφόρηση, στρατηγικές διαχείρισης, αλληλεπιδράσεις με το βρέφος και απόδοση ευθυνών.
description: The aim of the present postgraduate research was the study of the experiences of parents whose neonates were diagnosed with severe neurological impairment and prognosis while they were hospitalized in Neonatal Intensive Care Unit. The type of research was a retrospective qualitative study based on phenomenology principles. The main results were grouped in five main categories which are the first shock, information, copy strategies, interaction with infant and accountability.
Map completion from partial observation using the global structure of multiple environmental maps
Creators: name: Katsumata, Yuki
name: Kanechika, Akinori
name: Taniguchi, Akira
name: Hafi, Lotfi El
name: Hagiwara, Yoshinobu
name: Taniguchi, Tadahiro
Publisher: name: arXiv
Year: 2021
Subjects: subject: Robotics (cs.RO)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Using the spatial structure of various indoor environments as prior knowledge, the robot would construct the map more efficiently. Autonomous mobile robots generally apply simultaneous localization and mapping (SLAM) methods to understand the reachable area in newly visited environments. However, conventional mapping approaches are limited by only considering sensor observation and control signals to estimate the current environment map. This paper proposes a novel SLAM method, map completion network-based SLAM (MCN-SLAM), based on a probabilistic generative model incorporating deep neural networks for map completion. These map completion networks are primarily trained in the framework of generative adversarial networks (GANs) to extract the global structure of large amounts of existing map data. We show in experiments that the proposed method can estimate the environment map 1.3 times better than the previous SLAM methods in the situation of partial observation.
description: Accepted to Advanced Robotics
Centrality Dependence of Azimuthal Anisotropy of Strange Hadrons in 200 GeV Au+Au Collisions
Creators: name: Oldenburg, M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Measurements of azimuthal anisotropy for strange and multi-strange hadrons are presented for the first time in their centrality dependence. The high statistics results of v2(pT) allow for a more detailed comparison to hydrodynamical model calculations. Number-of-constituent-quark scaling was tested for different centrality classes separately. Higher order anisotropies like v4(pT) are measured for multi-strange hadrons. While we observe agreement between measured data and models a deeper understanding and refinement of the models seem to be necessary in order to fully understand the details of the data.
description: 4 pages, 2 figures; Strange Quark Matter 2006 conference proceedings, to appear in J. Phys. G
B-hadron hadro-production in NNLO QCD: application to LHC $t\bar{t}$ events with leptonic decays
Creators: name: Czakon, Michal
name: Generet, Terry
name: Mitov, Alexander
name: Poncelet, Rene
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We calculate, for the first time, the NNLO QCD corrections to identified heavy hadron production at hadron colliders. The calculation is based on a flexible numeric framework which allows the calculation of any distribution of a single identified heavy hadron plus jets and non-QCD particles. As a first application we provide NNLO QCD predictions for several differential distributions of $B$ hadrons in $t\bar t$ events at the LHC. Among others, these predictions are needed for the precise determination of the top quark mass. The extension of our results to other processes, like open or associated $B$ and charm production is straightforward. We also explore the prospects for extracting heavy flavor fragmentation functions from LHC data.
description: 27 pages, 29 figures
A numerical study of non-gaussianity in the curvaton scenario
Creators: name: Malik, Karim A.
name: Lyth, David H.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We study the curvaton scenario using gauge-invariant second order perturbation theory and solving the governing equations numerically. Focusing on large scales we calculate the non-linearity parameter f_nl in the two-fluid curvaton model and compare our results with previous analytical studies employing the sudden decay approximation. We find good agreement of the two approaches for large curvaton energy densities at curvaton decay, Omega_dec, but significant differences of up to 10 percent for small Omega_dec.
description: 15 pages, 9 figures, some in colour; v2: references added, typos corrected, section on curvaton evolution added; v3: typos corrected, corresponds to journal version
Longest Common Separable Pattern between Permutations
Creators: name: Bouvel, Mathilde
name: Rossin, Dominique
name: Vialette, Stephane
Publisher: name: arXiv
Year: 2007
Subjects: subject: Combinatorics (math.CO)
subject: Computational Complexity (cs.CC)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: 05A05 - 05C12 - 05C85 - 05C05- 90C39

description: In this article, we study the problem of finding the longest common separable pattern between several permutations. We give a polynomial-time algorithm when the number of input permutations is fixed and show that the problem is NP-hard for an arbitrary number of input permutations even if these permutations are separable. On the other hand, we show that the NP-hard problem of finding the longest common pattern between two permutations cannot be approximated better than within a ratio of $sqrt{Opt}$ (where $Opt$ is the size of an optimal solution) when taking common patterns belonging to pattern-avoiding classes of permutations.
description: 15 pages
Το συγγραφικό έργο της Κίρας Σίνου και η συμβολή της στην παιδική λογοτεχνία
Creators: name: Θεοδωρίδου, Μυροφόρα Κωνσταντίνου
Publisher: name: Aristotle University of Thessaloniki
Year: 2020
Subjects: Παιδική Λογοτεχνία
Κίρα Σίνου
Ιστορικό μυθιστόρημα
Children’s literature
Kira Sinou
Historical novel

description: Η παρούσα διπλωματική εργασία αποτελεί μία μελέτη του συγγραφικού έργου της Κίρας Σίνου. Ξεκινώντας με μία γενική θεώρηση της παιδικής λογοτεχνίας, η οποία περιλαμβάνει εννοιολογικές προσεγγίσεις, αλλά και την ιστορική της εξέλιξη στη χώρα μας, εστιάζουμε στην περίοδο που χρονολογούνται τα λογοτεχνικά έργα της συγγραφέως μας. Μελετούμε, επίσης, την ιδεολογία που εντοπίζεται γενικότερα στην παιδική λογοτεχνία, καθώς και τις επικρατέστερες αντιλήψεις για την παιδική ηλικία, θέλοντας να εξετάσουμε αν αυτές επηρεάζουν και τη συγγραφή λογοτεχνημάτων για παιδιά. Παρουσιάζουμε, ακόμη, συγκεκριμένες βιογραφικές πληροφορίες για τη συγγραφέα, τόσο για τη ζωή της όσο και την εργογραφία της. Σκοπός μας είναι, μέσα από τα μυθιστορήματα που επιλέξαμε, να ερευνήσουμε ποια είναι η συμβολή της Σίνου στην παιδική λογοτεχνία, ποια πρωτοποριακά λογοτεχνικά χαρακτηριστικά εντοπίζονται στα έργα της, και τέλος ποια είναι η εικόνα της παιδικής ηλικίας που παρουσιάζεται μέσω των βιβλίων της.
description: The present thesis is a study of Kira Sinou’s work. Taking initially a general view of children's literature, including conceptual approaches, as well as its historical development in Greece, we proceed to focus on the time period the author's work is dated from. We also study the ideology found in children's literature in general, along with the prevailing perceptions of childhood, in order to examine whether these also affect children's literature itself. In addition, specific information about the author's biography and work are presented. Our purpose, through the novels we chose, is to investigate the contribution of Sinou to children's literature, to identify the innovative literary features found in her work and, finally, to point out the image of childhood presented through her books.
Silent Light, Luminous Noise: Photophonics, Machines and the Senses
Creators: name: Mullender, Rob
Publisher: name: University of the Arts London
Year: 2024
Subjects: classificationCode: 369999
subject: Other creative arts and writing not elsewhere classified

description: Silent Light, Luminous Noise:Photophonics, Machines and the Senses PhDBy Rob Mullender2006 - 2012Supervisors: Angus Carlyle (DoS), David Toop and David CunninghamA digital copy of this thesis is available from the UAL Research Online repository.
Differential Morph Face Detection using Discriminative Wavelet Sub-bands
Creators: name: Chaudhary, Baaria
name: Aghdaie, Poorya
name: Soleymani, Sobhan
name: Dawson, Jeremy
name: Nasrabadi, Nasser M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Face recognition systems are extremely vulnerable to morphing attacks, in which a morphed facial reference image can be successfully verified as two or more distinct identities. In this paper, we propose a morph attack detection algorithm that leverages an undecimated 2D Discrete Wavelet Transform (DWT) for identifying morphed face images. The core of our framework is that artifacts resulting from the morphing process that are not discernible in the image domain can be more easily identified in the spatial frequency domain. A discriminative wavelet sub-band can accentuate the disparity between a real and a morphed image. To this end, multi-level DWT is applied to all images, yielding 48 mid and high-frequency sub-bands each. The entropy distributions for each sub-band are calculated separately for both bona fide and morph images. For some of the sub-bands, there is a marked difference between the entropy of the sub-band in a bona fide image and the identical sub-band's entropy in a morphed image. Consequently, we employ Kullback-Liebler Divergence (KLD) to exploit these differences and isolate the sub-bands that are the most discriminative. We measure how discriminative a sub-band is by its KLD value and the 22 sub-bands with the highest KLD values are chosen for network training. Then, we train a deep Siamese neural network using these 22 selected sub-bands for differential morph attack detection. We examine the efficacy of discriminative wavelet sub-bands for morph attack detection and show that a deep neural network trained on these sub-bands can accurately identify morph imagery.
description: CVPR Biometrics Workshop 2021
Multiple magnetic transitions and magnetocaloric effect in Gd1-xSmxMn2Ge2 compounds
Creators: name: Kumar, Pramod
name: Singh, Niraj K.
name: Suresh, K. G.
name: Nigam, A. K.
name: Malik, S. K.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Magnetic and magnetocaloric properties of polycrystalline samples of Gd1-xSmxMn2Ge2 have been studied. All the compounds except GdMn2Ge2 show re-entrant ferromagnetic behavior. Multiple magnetic transitions observed in these compounds are explained on the basis of the temperature dependences of the exchange strengths of the rare earth and Mn sublattices. Magnetocaloric effect is found to be positive at the re-entrant ferromagnetic transition, whereas it is negative at the antiferro-ferromagnetic transition. In SmMn2Ge2, the magnetic entropy change associated with the re-entrant transition is found to decrease with field, which is attributed to the admixture effect of the crystal field levels. The isothermal magnetic entropy change is found to decrease with increase in Sm concentration.
description: 8
Healthy communities in British Columbia : a case study of the Tri-City Health Promotion Project
Creators: name: Hill, Patricia M.
Publisher: name: University of British Columbia
Year: 2008

description: In recent years, the term "Healthy Communities" has become a catch phrase among planners, health promotion workers, social workers and government agencies, and increasing numbers of professionals have taken a role in the development of healthy communities projects. The literature on the healthy communities concept has increased in size and scope. Yet the concept itself is byno means clearly defined. Nor is there a standard method for developing a successful healthy communities project, or a regional collaboration of healthy communities projects. The question remains, when a planner undertakes a role in the development of a healthy communities project, what are the most important factors to consider? This thesis examines the influence of various project inputs on the ability of a regional healthy communities project to achieve its objectives. The thesis uses a case study of the Tri-City Health Promotion Project, a collaborative healthy communities project undertaken in the cities of Castlegar, Trail and Nelson in the West Kootenay region of British Columbia. In this study, documentary analysis and interviews with Tri-City project staff illuminate the importance of several influences on a regional healthy communities project. Some of these are: the approach used by the participants (task- orprocess-orientation), the resources and constraints specific to each community, the context from which the project grew, the personalities of those involved, the ability of the collaborating communities to work together, and the relationship between the community and regional bodies in the project structure. Conclusions: While every healthy communities project will be affected differently by various inputs, in the case of the Tri-City Health Promotion Project, the relationship between the regional and community bodies in the project structure had the greatest influence on the ability of the community Steering Committees to achieve their goals. Planners working on a regional healthy communities project must carefully examine the design of the project, in order to develop a structure which enhances the working relationship between regional and community bodies. This is particularly crucial in the healthy communities context, where decision-making power often resides at the community level, rather than being centralized in the regional body.
Frequency Correlation of QPOs Based on a Resonantly-Excited Disk-Oscillation Model
Creators: name: Kato, Shoji
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: In previous papers, we have proposed a model that the high-frequency quasi-periodic oscillations (HF QPOs) observed in black-hole and neutron-star X-ray binaries are inertial-acoustic oscillations that are resonantly excited on a one-armed deformed disk by nonlinear couplings between the oscillations and the disk deformation. In this paper we show that in addition to the inertial-acoustic waves, one-armed corrugation waves are also excited in the deformed disks. They are low-frequency oscillations. We examine frequencies and their correlations among the inertial-acoustic oscillations and the corrugation waves that are excited, in order to know whether they can describe observed frequency correlations among kHz QPOs and low-frequency QPOs (LF QPOs) in neutron-star X-ray binaries. The results seem to well describe the observed correlations in Cir X-1, if we adopt $M= 1.5\sim 2.0 M_\odot$ and $a_* \sim 0.8$, where $M$ is the mass of the central star and $a_*$ is the dimensionless spin parameter of the metric. Finally, assumptions involved in this disk-oscillation model are briefly summarized and discussed.
description: 18 pages, 9 figures, to be published in PASJ Vol. 60 (2008),No 4 (August)
Self-consistent models of cuspy triaxial galaxies with dark matter haloes
Creators: name: Capuzzo-Dolcetta, R.
name: Leccese, L.
name: Merritt, D.
name: Vicari, A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We have constructed realistic, self-consistent models of triaxial elliptical galaxies embedded in triaxial dark matter haloes. We examined three different models for the shape of the dark matter halo: (i) the same axis ratios as the luminous matter (0.7:0.86:1); (ii) a more prolate shape (0.5:0.66:1); (iii) a more oblate shape (0.7:0.93:1). The models were obtained by means of the standard orbital superposition technique introduced by Schwarzschild. Self-consistent solutions were found in each of the three cases. Chaotic orbits were found to be important in all of the models,and their presence was shown to imply a possible slow evolution of the shapes of the haloes. Our results demonstrate for the first time that triaxial dark matter haloes can co-exist with triaxial galaxies.
description: Latex paper based on the AASTEX format, 20 pages, 11 figures, 2 tables. Paper submitted to ApJ
Deep Learning strategies for ProtoDUNE raw data denoising
Creators: name: Rossi, Marco
name: Vallecorsa, Sofia
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Machine Learning (cs.LG)
subject: High Energy Physics - Experiment (hep-ex)
subject: Computational Physics (physics.comp-ph)
subject: Machine Learning (stat.ML)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: In this work, we investigate different machine learning-based strategies for denoising raw simulation data from the ProtoDUNE experiment. The ProtoDUNE detector is hosted by CERN and it aims to test and calibrate the technologies for DUNE, a forthcoming experiment in neutrino physics. The reconstruction workchain consists of converting digital detector signals into physical high-level quantities. We address the first step in reconstruction, namely raw data denoising, leveraging deep learning algorithms. We design two architectures based on graph neural networks, aiming to enhance the receptive field of basic convolutional neural networks. We benchmark this approach against traditional algorithms implemented by the DUNE collaboration. We test the capabilities of graph neural network hardware accelerator setups to speed up training and inference processes.
description: 9 pages, 7 figures, 3 tables. Code available at https://github.com/marcorossi5/DUNEdn
Diffusion and Thermalization in a Boundary-Driven Dephasing Model
Creators: name: Turkeshi, Xhek
name: Schiro, Marco
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We study a model of non-interacting spinless fermions coupled to local dephasing and boundary drive and described within a Lindblad master equation. The model features an interplay between infinite temperature thermalization due to bulk dephasing and a non-equilibrium stationary state due to the boundary drive and dissipation. We revisit the linear and non-linear transport properties of the model, featuring a crossover from ballistic to diffusive scaling, and compute the spectral and occupation properties encoded in the single particle Green's functions, that we compute exactly using the Lindblad equations of motion in spite of the \emph{interacting} nature of the dephasing term. We show that the distribution function in the bulk of the system becomes frequency independent and flat, consistent with infinite temperature thermalization, while near the boundaries it retains strong non-equilibrium features that reflect the continuous injection and depletion of particles due to driving and dissipation.
description: 11 pages
Dense molecular gas in a sample of LIRGs and ULIRGs: The low-redshift connection to the huge high-redshift starbursts and AGNs
Creators: name: Gracia-Carpio, J.
name: Garcia-Burillo, S.
name: Planesas, P.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The sample of nearby LIRGs and ULIRGs for which dense molecular gas tracers have been measured is building up, allowing for the study of the physical and chemical properties of the gas in the variety of objects in which the most intense star formation and/or AGN activity in the local universe is taking place. This characterisation is essential to understand the processes involved, discard others and help to interpret the powerful starbursts and AGNs at high redshift that are currently being discovered and that will routinely be mapped by ALMA. We have studied the properties of the dense molecular gas in a sample of 17 nearby LIRGs and ULIRGs through millimeter observations of several molecules (HCO+, HCN, CN, HNC and CS) that trace different physical and chemical conditions of the dense gas in these extreme objects. In this paper we present the results of our HCO+ and HCN observations. We conclude that the very large range of measured line luminosity ratios for these two molecules severely questions the use of a unique molecular tracer to derive the dense gas mass in these galaxies.
description: 4 pages, 4 figures, to appear in Astrophysics and Space Science, special issue of "Science with ALMA: a new era for Astrophysics" conference, ed. Dr. Bachiller
Computational power of one- and two-dimensional dual-unitary quantum circuits
Creators: name: Suzuki, Ryotaro
name: Mitarai, Kosuke
name: Fujii, Keisuke
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Complexity (cs.CC)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Quantum circuits that are classically simulatable tell us when quantum computation becomes less powerful than or equivalent to classical computation. Such classically simulatable circuits are of importance because they illustrate what makes universal quantum computation different from classical computers. In this work, we propose a novel family of classically simulatable circuits by making use of dual-unitary quantum circuits (DUQCs), which have been recently investigated as exactly solvable models of non-equilibrium physics, and we characterize their computational power. Specifically, we investigate the computational complexity of the problem of calculating local expectation values and the sampling problem of one-dimensional DUQCs, and we generalize them to two spatial dimensions. We reveal that a local expectation value of a DUQC is classically simulatable at an early time, which is linear in a system length. In contrast, in a late time, they can perform universal quantum computation, and the problem becomes a BQP-complete problem. Moreover, classical simulation of sampling from a DUQC turns out to be hard.
description: 14 pages, 6 figures
Βαθιά ενισχυτική μάθηση για ενεργή ρομποτική αντίληψη
Creators: name: Τιριτίρης, Παύλος Ιωάννη
Publisher: name: Aristotle University of Thessaloniki
Year: 2020
Subjects: Βαθιά ενισχυτική μάθηση
Ρομποτική όραση
Συνελικτικά νευρωνικά δίκτυα
Deep reinforcement learning
Robotic vision
Convolutional neural networks

description: Η ενισχυτική μάθηση είναι ένα σημαντικό εργαλείο για να λύνουμε περίπλοκα και απρόβλεπτα προβλήματα λήψης διαδοχικών αποφάσεων, που αντιμετωπίζουμε σε πολλές εφαρμογές στο πραγματικό κοσμο. Σε αυτήν την ερευνητική εργασία μελετάμε την ενεργή παρακολούθηση αντικειμένων, όπου ένας πράκτορας-ιχνηλάτης λαμβάνει ως είσοδο οπτική πληροφορία για να ελένξει τις κινήσεις της κάμερας. Κάποιες κλασσικές μέθοδοι λύνουν ξεχωριστά το πρόβλημα της παρακολούθησης και του ελένχου, κάτι που το κάνει δύσκολο να συνδιαστούν μαζί. Επίσης απαιτείται αρκετή γνώστη στο πεδίο του προβλήματος για να γίνει σωστά η αναγνώριση και μπορεί να κοστίσει πολλές προσπάθειες για να μάθει να λύνει σωστά το πρόβλημα στον πραγματικό κόσμο. Για να αποφύγουμε τέτοια προβλήματα, σε αυτήν την εργασία παρουσιάζουμε μια προσέγγιση βαθιάς ενισχυτικής μάθησης, χρησιμοποιώντας το μοντέλο actor-critic με μια απλή αρχιτεκτονική συνελικτικού νευρωνικού δικτύου. Η εκπαίδευση γίνεται στο περιβάλλον προσομοίωσης Webots και εμφανίζει πολύ καλά αποτελέσματα σε ποικίλες τροχιές ενός κινητού αντικειμένου.
description: Reinforcement learning offers a general framework for solving complex and unpredictable sequential decision problems which are encountered in many applications in the real world. We study active object tracking, where a tracker takes visual observation (i.e. frame sequence) as an input and generates the camera control movements. Conventional approaches address separately the tracking and the camera control, which is difficult to balance together. It also requires enough individual knowledge for labeling and many expensive realworld trials-and-errors. To address these issues, we propose in this paper, a simple solution via deep reinforcement learning, where we apply actorcritic model with a simple convolutional neural network architecture. The tracker trained in Webots simulation environment shows good generalization on various dynamic trajectories of the moving object.
Inverse Higgs phenomena as duals of holonomic constraints
Creators: name: Gripaios, Ben
name: Tooby-Smith, Joseph
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The inverse Higgs phenomenon, which plays an important rôle in physical systems with Goldstone bosons (such as the phonons in a crystal) involves nonholonomic mechanical constraints. By formulating field theories with symmetries and constraints in a general way using the language of differential geometry, we show that many examples of constraints in inverse Higgs phenomena fall into a special class, which we call coholonomic constraints, that are dual (in the sense of category theory) to holonomic constraints. Just as for holonomic constraints, systems with coholonomic constraints are equivalent to unconstrained systems (whose degrees of freedom are known as essential Goldstone bosons), making it easier to study their consistency and dynamics. The remaining examples of inverse Higgs phenomena in the literature require the dual of a slight generalisation of a holonomic constraint, which we call (co)meronomic. Our formalism simplifies and clarifies the many ad hoc assumptions and constructions present in the literature. In particular, it identifies which are necessary and which are merely convenient. It also opens the way to studying much more general dynamical examples, including systems which have no well-defined notion of a target space.
description: 28 pages. v2: version accepted for publication
Dust and Gas in the Local Environments of Gamma-Ray Bursts
Creators: name: Schady, P.
name: Mason, K. O.
name: Page, M. J.
name: De Pasquale, M.
name: Morris, D. C.
name: Romano, P.
name: Roming, P. W. A.
name: Immler, S.
name: Berk, D. E. Vanden
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Using a sample of gamma-ray burst (GRB) afterglows detected by both the X-Ray and the UV/Optical Telescopes (XRT and UVOT) on Swift, we modelled the spectral energy distributions (SEDs) to determine gas column densities and dust extinction in the GRB local environment. In six out of seven cases we find an X-ray absorber associated with the GRB host galaxy with column density (assuming solar abundances) ranging from (0.8 - 7.7)x10^{21}cm^{-2}. We determine the rest-frame visual extinction A_V using the SMC, LMC and Galactic extinction curves to model the dust in the GRB host galaxy, and this ranges from A_V = 0.12\pm 0.04 to A_V = 0.65^{+0.08}_{-0.07}. The afterglow SEDs were typically best fit by a model with an SMC extinction curve. In only one case was the GRB afterglow better modelled by a Galactic extinction curve, which has a prominent absorption feature at 2175angstrom. We investigate the selection effects present in our sample and how these might distort the true distribution of A_V in GRB host galaxies. We estimate that GRBs with no afterglow detected blueward of 5500angstrom have average rest-frame visual extinctions almost eight times those observed in the optically bright population of GRBs. This may help account for the ~1/3 of GRBs observed by Swift that have no afterglow detected by UVOT.
description: Corrected typos 13 pages, 8 figures, MNRAS, 2007, 377, 273
Connected and Automated Vehicle Distributed Control for On-ramp Merging Scenario: A Virtual Rotation Approach
Creators: name: Chen, Tianyi
name: Wang, Meng
name: Gong, Siyuan
name: Zhou, Yang
name: Ran, Bin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Systems and Control (eess.SY)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: In this study, we propose a rotation-based connected automated vehicle (CAV) distributed cooperative control strategy for an on-ramp merging scenario. By assuming the mainline and ramp line are straight, we firstly design a virtual rotation approach that transfers the merging problem to a virtual car following (CF) problem to reduce the complexity and dimension of the cooperative CAVs merging control. Based on this concept, a multiple-predecessor virtual CF model and a unidirectional multi-leader communication topology are developed to determine the longitudinal behavior of each CAV. Specifically, we exploit a distributed feedback and feedforward longitudinal controller in preparation for actively generating gaps for merging CAVs, reducing the voids caused by merging, and ensuring safety and traffic efficiency during the process. To ensure the disturbance attenuation property of this system, practical string stability is mathematically proved for the virtual CF controllers to prohibit the traffic oscillation amplification through the traffic stream. Moreover, as a provision for extending the virtual CF application scenarios of any curvy ramp geometry, we utilize a curvilinear coordinate to model the two-dimensional merging control, and further design a local lateral controller based on an extended linear-quadratic regulator to regulate the position deviation and angular deviation of the lane centerlines. For the purpose of systematically evaluating the control performance of the proposed methods, numerical simulation experiments are conducted. As the results indicate, the proposed controllers can actively reduce the void and meanwhile guarantee the damping of traffic oscillations in the merging control area.
description: 30 pages, 15 figures, 2 tables
Dirac Quantization of Parametrized Field Theory
Creators: name: Varadarajan, Madhavan
Publisher: name: arXiv
Year: 2006
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Parametrized field theory (PFT) is free field theory on flat spacetime in a diffeomorphism invariant disguise. It describes field evolution on arbitrary foliations of the flat spacetime instead of only the usual flat ones, by treating the `embedding variables' which describe the foliation as dynamical variables to be varied in the action in addition to the scalar field. A formal Dirac quantization turns the constraints of PFT into functional Schrodinger equations which describe evolution of quantum states from an arbitrary Cauchy slice to an infinitesimally nearby one.This formal Schrodinger picture- based quantization is unitarily equivalent to the standard Heisenberg picture based Fock quantization of the free scalar field if scalar field evolution along arbitrary foliations is unitarily implemented on the Fock space. Torre and Varadarajan (TV) showed that for generic foliations emanating from a flat initial slice in spacetimes of dimension greater than 2, evolution is not unitarily implemented, thus implying an obstruction to Dirac quantization. We construct a Dirac quantization of PFT,unitarily equivalent to the standard Fock quantization, using techniques from Loop Quantum Gravity (LQG) which are powerful enough to super-cede the no- go implications of the TV results. The key features of our quantization include an LQG type representation for the embedding variables, embedding dependent Fock spaces for the scalar field, an anomaly free representation of (a generalization of) the finite transformations generated by the constraints and group averaging techniques. The difference between 2 and higher dimensions is that in the latter, only finite gauge transformations are defined in the quantum theory, not the infinitesimal ones.
description: 33 pages
The stationary solutions of G-P equations in double square well
Creators: name: Li, Weidong
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We present analytical stationary solutions for the Gross-Pitaevskii equation (GPE) of a Bose-Einstein condensate (BECs) trapped in a double-well potential. These solutions are compared with those described by [Mahmud et al., PRA \textbf{66}, 063607 (2002)]. In particular, we provide further evidence that symmetry preserving stationary solutions can be reduced to the eigenstates of the corresponding linear Schrödinger equation. Moreover, we have found that the symmetry breaking solutions can emerge not only from bifurcations, but also from isolated points in the chemical potential-nonlinear interaction diagram. We also have found that there are some moving nodes in the symmetry breaking solutions.
description: 7 pages, 4 figures
A first-principles investigation of band inversion in topologically nontrivial Na2AgX (X= As, Sb and Bi) full Heusler compounds
Creators: name: Boughena, A.
name: Benalia, S.
name: Cheref, O.
name: Bettahar, N.
name: Rached, D.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Topological nontrivial nature are the latest phases to be discovered in condensed matter physics with insulating bulk band gaps and topologically protected metallic surface states; they are one of the current hot topics because of their unique properties and potential applications. In this paper, we have highlighted a first-principles study of the structural stability and electronic behavior of the Na${}_{2}$AgX (X= As, Sb and Bi) full Heusler compounds, using the Full-Potential Linear Muffin-Tin Orbital (FP-LMTO) method. We have originated that the Hg${}_{2}$CuTi structure is appropriate in all studied materials. The negative values of the calculated formation energies mean that these compounds are energetically stable. The band structure is studied for the two cases relating the existence and the absence of spin-orbital couplings, where all materials are shown to be topologically non-trivial compounds. Spin orbital couplings were noticed to have no significant effect on the electronic properties such as the topological order.
description: 7 pages, 2 figures, 1 table
Solar Atmospheric Oscillations and the Chromospheric Magnetic Topology
Creators: name: Vecchio, A.
name: Cauzzi, G.
name: Reardon, K. P.
name: Janssen, K.
name: Rimmele, T.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We investigate the oscillatory properties of the quiet solar chromosphere in relation to the underlying photosphere, with particular regard to the effects of the magnetic topology. We perform a Fourier analysis on a sequence of line-of-sight velocities measured simultaneously in a photospheric (Fe I 709.0 nm) and a chromospheric line (Ca II 854.2 nm). The velocities were obtained from full spectroscopic data acquired at high spatial resolution with the Interferometric BIdimensional Spectrometer (IBIS). The field of view encompasses a full supergranular cell, allowing us to discriminate between areas with different magnetic characteristics. We show that waves with frequencies above the acoustic cut-off propagate from the photosphere to upper layers only in restricted areas of the quiet Sun. A large fraction of the quiet chromosphere is in fact occupied by ``magnetic shadows'', surrounding network regions, that we identify as originating from fibril-like structures observed in the core intensity of the Ca II line. We show that a large fraction of the chromospheric acoustic power at frequencies below the acoustic cut-off, residing in the proximity of the magnetic network elements, directly propagates from the underlying photosphere. This supports recent results arguing that network magnetic elements can channel low-frequency photospheric oscillations into the chromosphere, thus providing a way to input mechanical energy in the upper layers.
description: 4 pages, 3 figure, A&A Letters in press
Being positive: women living with HIV and AIDS in British Columbia
Creators: name: Howard, Carol H.
Publisher: name: University of British Columbia
Year: 2008

description: The following study is a phenomenological inquiry into five white, middle classwomen's experiences living with HIV and AIDS in British Columbia. The purpose, rather than describing AIDS as a medical phenomenon, is to document how being diagnosed HIV positive has affected the women's lives, health, relationships and livelihoods. A context for the women's stories is provided through a critical review of the biomedical model, as well as biomedical and community organizing perspectives on women and AIDS. Mostly verbatim accounts drawn from taped interviews conducted with the five women describes their lives with HIV and AIDS. Experiences surrounding their diagnosis, sources of information about their illness, strategies for coping, management of health, and management of personal and social identities are the themes explored. The women's participation, the role of the researcher, and the work produced are considered parts of an interactive process, demonstrating shared authority between the researcher and participants in the ethnographic process. Documentation of the women's experiences leads to a discussion of the ways in which they successfully manage and control their own health care and well being within the context of larger social forces of sexism, medical bias and stigma. The women are given the last word in the study. In conclusion, a review oftheir situations three years after their initial interviews contributes a significant emotional and descriptive time-depth to the study.
Effects of the Energy Error Distribution of Fluorescence Telescopes on the UHECR energy spectrum
Creators: name: Carvalho, Washington
name: Albuquerque, Ivone F. M.
name: de Souza, Vitor
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The measurement of the ultra high energy cosmic ray (UHECR) spectrum is strongly affected by uncertainties on the reconstructed energy. The determination of the presence or absence of the GZK cutoff and its position in the energy spectrum depends not only on high statistics but also on the shape of the energy error distribution. Here we determine the energy error distribution for fluorescence telescopes, based on a Monte Carlo simulation. The HiRes and Auger fluorescence telescopes are simulated in detail. We analyze the UHECR spectrum convolved with this energy error distribution. We compare this spectrum with one convolved with a lognormal error distribution as well as with a Gaussian error distribution. We show that the energy error distribution for fluorescence detectors can not be represented by these known distributions. We conclude that the convolved energy spectrum will be smeared but not enough to affect the GZK cutoff detection. This conclusion stands for both HiRes and Auger fluorescence telescopes. This result differs from the effect of the energy error distribution obtained with ground detectors and reinforces the importance of the fluorescence energy measurement. We also investigate the effect of possible fluorescence yield measurement errors in the energy spectrum.
description: 24 pages, 11 figures
Flavor symmetry and decays of charmed mesons to pairs of light pseudoscalars
Creators: name: Bhattacharya, Bhubanjyoti
name: Rosner, Jonathan L.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: New data on the decays of the charmed particles $D^0$, $D^+$, and $D_s$ to pairs of light pseudoscalar mesons $P$ allow the testing of flavor symmetry and the extraction of key amplitudes. Information on relative strong phases is obtained. One sees evidence for the expected interference between Cabibbo-favored and doubly-Cabibbo-suppressed decays in the differing patterns of $D^0 \to K_{S,L} π^0$ and $D^+ \to K_{S,L} π^+$ decays.
description: 12 pages, 5 figures, to be submitted to Phys. Rev. D
Το μουσείο ως χώρος αξιοποίησης του ελεύθερου χρόνου του ενήλικου κοινού: Έρευνα και αξιολόγηση του προγράμματος “Adult Art” στο MOMus- Μουσείο Σύγχρονης Τέχνης Θεσσαλονίκης
Creators: name: Πιπινά, Φωτεινή Γεωργίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2020
Subjects: Μουσείο
Εκπαιδευτικό πρόγραμμα ενηλίκων σε μουσείο
Ελεύθερος χρόνος ενηλίκων
Museum
Educational program in museum for adults
Adult leisure time

description: Η παρούσα μεταπτυχιακή εργασία ασχολείται με τον εκπαιδευτικό ρόλο των μουσείων τονίζοντας την σημασία των εκπαιδευτικών προγραμμάτων που λαμβάνουν χώρο σε ένα μουσείο. Πιο συγκεκριμένα, εστιάζει στην σχέση του μουσείου με το ενήλικο κοινό του, σχολιάζοντας θέματα δια βίου μάθησης και ενηλικότητας. Στα πλαίσια της εργασίας αυτής διενεργήθηκε μια ποιοτική έρευνα σε ένα εκπαιδευτικό πρόγραμμα για ενήλικες που διεξάγεται στο MOMus-Μουσείο Σύγχρονης Τέχνης Θεσσαλονίκης με τίτλο “Adult Art”. Σκοπός της έρευνας ήταν να αξιολογηθεί το πρόγραμμα αυτό μέσα από τις εμπειρίες των συμμετεχόντων. Τέλος παρουσιάζονται και συζητιούνται τα αποτελέσματα της έρευνας αυτής.
description: The dissertation touches upon the educational role of museums and underlines the importance of museum education through learning programs. It emphasizes the importance of addressing to adult learners/visitors and explains the components when it comes to lifelong learning for adults. Then, the dissertation studies a program addressed to adults at MOMus-Museum of Contemporary Art, Thessaloniki, named “Adult Art”. In order to research and evaluate the program, interviews with the participants were contacted. The master thesis is completed when the results of the research are presented and discussed.
description: Σε συνεργασία με: Παιδαγωγικό Δημοτικής Εκπαίδευσης (Πανεπιστήμιο Δυτικής Μακεδονίας)
Numerical and experimental investigation of rubber-road friction including the effect of flash temperature
Creators: name: Grigoriadis, Kyriakos
Publisher: name: Loughborough University
Year: 2021
Subjects: classificationCode: 409999
subject: Other engineering not elsewhere classified

description: Tyres are a critical component for vehicle handling, safety and performance. Vehicles must operate at the limit of friction in the case of emergency manoeuvres in both manual and autonomous driving, while in motorsport, using the whole of the available friction envelope provides a distinct competitive advantage. Therefore, better understanding of the physics of rubber-road friction, together with the development of efficient numerical tools, allows researchers and engineers to predict friction on different surfaces more reliably, and, based on these predictions, to make better design decisions in the form of more effective control systems or a more fine-tuned vehicle set-up. Modeling tyre tread sliding friction on a dry road surface, considering interaction at many roughness levels coupled with the effect of extreme local heating, is the aim of this dissertation and a rather challenging task. The work first focuses on the numerical implementation of Persson’s multi-scale, flash temperature friction model. A mathematical formula is developed to reproduce viscoelastic modulus by means of polynomials. The empirical formulation ensures faster computation time, and allows the effect of hypothetical rubber material models to be assessed. An implicit method for flash temperature calculation is developed using a logistic function adaptation, aiming to further reduce computational time and to offer resolution-free solution of the numerically-solved integrals found in the physical model examined herein. i The bounds of friction in the existence of several ill-defined or difficult-to-measure model parameters are obtained through a systematic sensitivity study of Persson’s model. For the evaluation of the predictions of the aforementioned rubber friction model, a test rig apparatus for in-field operation is designed and built. Unlike existing test setups, the proposed one allows measurements at realistically high speeds, on real road surfaces and with measurement of the temperature near the contact. Measured and predicted friction and local temperature showed promising correlation across a range of operational conditions.
Neutral kaon mixing from 2+1 flavor Domain Wall QCD
Creators: name: Antonio, D. J.
name: Boyle, P. A.
name: Blum, T.
name: Christ, N. H.
name: Cohen, S. D.
name: Dawson, C.
name: Izubuchi, T.
name: Kenway, R. D.
name: Jung, C.
name: Li, S.
name: Lin, M. F.
name: Mawhinney, R. D.
name: Noaki, J.
name: Ohta, S.
name: Pendleton, B. J.
name: Scholz, E. E.
name: Soni, A.
name: Tweedie, R. J.
name: Yamaguchi, A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We present the first results for neutral kaon mixing using 2+1 flavors of domain wall fermions. A new approach is used to extrapolate to the physical up and down quark masses from our numerical studies with pion masses in the range 240 -- 420 MeV; only $SU(2)_L \times SU(2)_R$ chiral symmetry is assumed and the kaon is not assumed to be light. Our main result is $B_K^{\bar{\rm MS}}(2 \mathrm{GeV}) = 0.524(10)(28)$ where the first error is statistical and the second incorporates estimates for all systematic errors.
description: 4 pages, 4 figures. RBC and UKQCD collaborations