cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Theoretical and Numerical Investigation of Nonlinear Thermoacoustic, Acoustic, and Detonation Waves
Creators: name: Gupta, Prateek
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We begin with the theoretical study of spectral energy cascade due to the propagation of high amplitude sound in the absence of thermal sources. To this end, a first-principles-based system of governing equations, correct up to second order in perturbation variables is derived. The exact energy corollary of such second-order system of equations is then formulated and used to elucidate the spectral energy dynamics of nonlinear acoustic waves. We then extend this analysis to thermoacoustically unstable waves -- i.e. amplified as a result of thermoacoustic instability. We drive such instability up until the generation of shock waves. We further study the nonlinear wave propagation in geometrically complex case of waves induced by the spark plasma between the electrodes. This case adds the geometrical complexity of a curved, three-dimensional shock, yielding vorticity production due to baroclinic torque. Finally, detonation waves are simulated by using a low-order approach, in a periodic setup subjected to high pressure inlet and exhaust of combustible gaseous mixture. An order adaptive fully compressible and unstructured Navier Stokes solver is currently under development to enable higher fidelity studies of both the spark plasma and detonation wave problem in the future.
description: Purdue University Graduate School. Thesis (2019)
Εφαρμογή Τεχνολογιών Αισθητήρων στην Ηλεκτρονική Διακυβέρνηση
Creators: name: Πατήλας, Νικόλαος Δημητρίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2020
Subjects: Ηλεκτρονική Συνοικία
Ηλεκτρονική Διακυβέρνηση
Διαδίκτυο των Πραγμάτων
E-synoikia
E-government
Internet of Things

description: Στις μέρες μας παρατηρείται μεγάλη αύξηση στην υλοποίηση δικτύων αισθητήρων και στην ανάκτηση πληροφοριών και δεδομένων από το λεγόμενο Διαδίκτυο των Πραγμάτων (Internet Of Things). Το διαδίκτυο των πραγμάτων μπορεί να διαδραματίσει σημαντικό ρόλο στη βελτίωση της ηλεκτρονικής διακυβέρνησης, με στόχο τη βελτίωση της ποιότητας ζωής των κατοίκων μίας χώρας ή ενός δήμου. Στην τρέχουσα εργασίας γίνεται ανάλυση της ηλεκτρονικής διακυβέρνησης με τη χρήση συστημάτων του διαδικτύου των πραγμάτων, αναλύονται συσκευές μικροελεγκτών που χρησιμοποιούνται σε εφαρμογές του IoT και παρουσιάζεται μία συσκευή με έναν κύκλωμα αισθητήρων που μπορεί να χρησιμοποιηθεί ως επέκταση της πλατφόρμας του e-synoikia. Τέλος, γίνεται ανάλυση των δειγμάτων που λήφθηκαν με τη χρήση της τρέχουσας συσκευής.
description: Nowadays there is a great increase in the implementation of sensor networks and the retrieval of information and data from the Internet of Things. The Internet of Things can play an important role in improving e-government, with the aim of improving the quality of life of people in one country or municipality. Current work analyzes e-government using Internet of Things systems, analyzes microcontrollers used in IoT applications, and presents a device with a sensor circuit that can be used as an extension of the e-synoikia platform. Finally, the samples taken using the current device are analyzed.
Self-Consistent Theory of Bose-Condensed Systems
Creators: name: Yukalov, V. I.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In the theory of Bose-condensed systems, there exists the well known problem, the Hohenberg-Martin dilemma of conserving versus gapless approximations. This dilemma is analysed and it is shown that it arises because of the internal inconsistency of the standard grand ensemble, as applied to Bose-systems with broken global gauge symmetry. A solution of the problem is proposed, based on the notion of representative statistical ensembles, taking into account all constraints imposed on the system. A general approach for constructing representative ensembles is formulated. Applying a representative ensemble to Bose-condensed systems results in a completely self-consistent theory, both conserving and gapless in any approximation.
description: Latex file, 12 pages
Dispersive neural networks for adaptive signal processing
Creators: name: Day, Shawn P.
Publisher: name: University of British Columbia
Year: 2008

description: Back-propagation is a popular method for training feed-forward neural networks. This thesis extends the back-propagation technique to dispersive networks, which contain internal delay elements. Both the delays and the weights adapt to minimize the error at the output. Dispersive networks can perform many tasks, including signal prediction, signal production, channel equalization, and spatio-temporal pattern recognition. For comparison with conventional techniques, a dispersive network was trained to predict future values of a chaotic signal using only its present value as an input. With adaptable delays, the network had less than half the prediction error of an identical network with fixed delays, and about one-quarter the error of a conventional back-propagation network. Moreover, a dispersive network can simultaneously adapt and predict, while a conventional network cannot. After training as a predictor, the network was placed in a signal production configuration, where it autonomously generated a close approximation to the training signal. The power spectrum of the network output was a good reproduction of the training signal spectrum. Networks with fixed time delays produced much less accurate power spectra, and conventional back-propagation networks were unstable, generating high-frequency oscillations. Dispersive networks also showed an improvement over conventional techniques in an adaptive channel equalization task, where the channel transfer function was nonlinear. The adaptable delays in the dispersive network allowed it to reach a lower error than other equalizers, including a conventional back-propagation network and an adaptive linear filter. However, the improved performance came at the expense of a longer training time. Dispersive networks can be implemented in serial or parallel form, using digital electronic circuitry. Unlike conventional back-propagation networks, they can operate in a fully pipelined fashion, leading to a higher signal throughput. Their implementation in analog hardware is a promising area for future research.
Kondo effect in quantum dots coupled to ferromagnetic leads with noncollinear magnetizations: effects due to electron-phonon coupling
Creators: name: Swirkowicz, R.
name: Wilczynski, M.
name: Barnas, J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Spin-polarized transport through a quantum dot strongly coupled to ferromagnetic electrodes with non-collinear magnetic moments is analyzed theoretically in terms of the non-equilibrium Green function formalism. Electrons in the dot are assumed to be coupled to a phonon bath. The influence of electron-phonon coupling on tunnelling current, linear and nonlinear conductance, and on tunnel magnetoresistance is studied in detail. Variation of the main Kondo peaks and phonon satellites with the angle between magnetic moments of the leads is analyzed.
description: 19 pages, 6 figures
A functional CLT for the occupation time of a state-dependent branching random walk
Creators: name: Birkner, Matthias
name: Zähle, Iljana
Publisher: name: arXiv
Year: 2007
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60K35 (Primary)

description: We show that the centred occupation time process of the origin of a system of critical binary branching random walks in dimension $d\ge 3$, started off either from a Poisson field or in equilibrium, when suitably normalized, converges to a Brownian motion in $d\ge4$. In $d=3$, the limit process is a fractional Brownian motion with Hurst parameter 3/4 when starting in equilibrium, and a related Gaussian process when starting from a Poisson field. For (dependent) branching random walks with state dependent branching rate we obtain convergence in f.d.d. to the same limit process, and for $d=3$ also a functional limit theorem.
description: Published in at http://dx.doi.org/10.1214/009117907000000150 the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org)
When scale is surplus
Creators: name: Gryb, Sean
name: Sloan, David
Publisher: name: arXiv
Year: 2021
Subjects: subject: History and Philosophy of Physics (physics.hist-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study a long-recognised but under-appreciated symmetry called "dynamical similarity" and illustrate its relevance to many important conceptual problems in fundamental physics. Dynamical similarities are general transformations of a system where the unit of Hamilton's principal function is rescaled, and therefore represent a kind of dynamical scaling symmetry with formal properties that differ from many standard symmetries. To study this symmetry, we develop a general framework for symmetries that distinguishes the observable and surplus structures of a theory by using the minimal freely specifiable initial data for the theory that is necessary to achieve empirical adequacy. This framework is then applied to well-studied examples including Galilean invariance and the symmetries of the Kepler problem. We find that our framework gives a precise dynamical criterion for identifying the observables of those systems, and that those observables agree with epistemic expectations. We then apply our framework to dynamical similarity. First we give a general definition of dynamical similarity. Then we show, with the help of some previous results, how the dynamics of our observables leads to singularity resolution and the emergence of an arrow of time in cosmology.
description: 1 figure. Version accepted to Synthese. Substantive improvements and clarifications
How to Calculate the Exponential of Matrices
Creators: name: Fujii, Kazuyuki
name: Oike, Hiroshi
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: How to calculate the exponential of matrices in an explicit manner is one of fundamental problems in almost all subjects in Science. Especially in Mathematical Physics or Quantum Optics many problems are reduced to this calculation by making use of some approximations whether they are appropriate or not. However, it is in general not easy. In this paper we give a very useful formula which is both elementary and getting on with computer.
description: Latex ; 15 pages ; 1 figure. The result is not new unfortunately, while the method is elementary and new. Since the formula is very convenient, it may be worth recording
Combining distribution-based neural networks to predict weather forecast probabilities
Creators: name: Clare, Mariana
name: Jamil, Omar
name: Morcrette, Cyril
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences
subject: I.6.5; I.2.6; G.3
subject: 68T07 (Primary), 86A10, 8604

description: The success of deep learning techniques over the last decades has opened up a new avenue of research for weather forecasting. Here, we take the novel approach of using a neural network to predict full probability density functions at each point in space and time rather than a single output value, thus producing a probabilistic weather forecast. This enables the calculation of both uncertainty and skill metrics for the neural network predictions, and overcomes the common difficulty of inferring uncertainty from these predictions. This approach is data-driven and the neural network is trained on the WeatherBench dataset (processed ERA5 data) to forecast geopotential and temperature 3 and 5 days ahead. Data exploration leads to the identification of the most important input variables, which are also found to agree with physical reasoning, thereby validating our approach. In order to increase computational efficiency further, each neural network is trained on a small subset of these variables. The outputs are then combined through a stacked neural network, the first time such a technique has been applied to weather data. Our approach is found to be more accurate than some numerical weather prediction models and as accurate as more complex alternative neural networks, with the added benefit of providing key probabilistic information necessary for making informed weather forecasts.
description: 21 pages, 14 figures, Github repository: https://github.com/mc4117/ResNet_Weather, Submitted to Quarterly Journal of the Royal Meteorological Society
Αισθητική προσέγγιση του δασικού οικοσυστήματος μέσα στη διαχρονία του χώρου της τέχνης
Creators: name: Τζιγγίδου, Ελένη Χρήστου
Publisher: name: Aristotle University of Thessaloniki
Year: 2020
Subjects: Τέχνη
Περιβάλλον
Ανθρωπος
Art
Human
Nature

description: Τα δασικά οικοσυστήματα και ο άνθρωπος, από την απαρχή της ύπαρξής του, βρίσκονταν σε συνεχή αλληλεπίδραση. Αυτή η αλληλεπίδραση, οδήγησε στο να συναντάται το δασικό οικοσύστημα σε πλήθος μορφών τέχνης κατά τη διάρκεια των αιώνων, παρατηρούμενο μέσω της ανθρώπινης σκοπιάς, η οποία άλλαζε συνεχώς, καθώς άλλαζε η σχέση του ανθρώπου με το δάσος με την πάροδο των χρόνων. Στην προκειμένη εργασία, μέσω της μελέτης διαφόρων έργων τέχνης (πίνακες ζωγραφικής, λογοτεχνικά αποσπάσματα, ποιήματα, κινηματογραφικές σκηνές, γλυπτά κτλ.) γίνεται αναφορά στην αισθητική προσέγγιση, τον τρόπο αποτύπωσης του συμβολισμού και την οπτική γωνία που προσεγγίζονται τα δασικά οικοσυστήματα από τον άνθρωπο, μέσα από το πέρασμα του χρόνου. Με τη μελέτη αυτή, θα γίνει προσπάθεια κατανόησης της επίδρασης του δάσους στον άνθρωπο και πως αυτή άλλαζε μέσα στη διαχρονία.
description: Forest ecosystems and humans from the beginning of his existence was in constant interaction. As a result forest ecosystem can be observed in different types of art through the centuries. The observation was constantly changing due to the changing of the relationships between human kind and forest through the years. In this project we will study different artworks (paintings, literature, theater etc.) analyzing the aesthetic aspect the way that forest ecosystems are presented the symbolism that we found in these artworks and the change of the point of view through the centuries. We will try to understand the effect of forests and nature to human and how that changed.
Transport through a quantum dot with SU(4) Kondo entanglement
Creators: name: Hur, K. Le
name: Simon, P.
name: Loss, D.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We investigate a mesoscopic setup composed of a small electron droplet (dot) coupled to a larger quantum dot (grain) also subject to Coulomb blockade as well as two macroscopic leads used as source and drain. An exotic Kondo ground state other than the standard SU(2) Fermi liquid unambiguously emerges: an SU(4) Kondo correlated liquid. The transport properties through the small dot are analyzed for this regime, through boundary conformal field theory, and allow a clear distinction with other regimes such as a two-channel spin state or a two-channel orbital state.
description: 13 pages, 3 figures
Supplementary files for Understanding the ecological versatility of Tetracladium species in temperate forest soil
Creators: name: Lazar, Anna
name: Phillips, Richard P.
name: Kivlin, Stephanie
name: Bending, Gary D.
name: Mushinski, Ryan M.
Publisher: name: figshare
Year: 2024
Subjects: classificationCode: 310705
subject: Mycology

description: Supplementary files for Understanding the ecological versatility of Tetracladium species in temperate forest soil
Learning a Product Relevance Model from Click-Through Data in E-Commerce
Creators: name: Yao, Shaowei
name: Tan, Jiwei
name: Chen, Xi
name: Yang, Keping
name: Xiao, Rong
name: Deng, Hongbo
name: Wan, Xiaojun
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: The search engine plays a fundamental role in online e-commerce systems, to help users find the products they want from the massive product collections. Relevance is an essential requirement for e-commerce search, since showing products that do not match search query intent will degrade user experience. With the existence of vocabulary gap between user language of queries and seller language of products, measuring semantic relevance is necessary and neural networks are engaged to address this task. However, semantic relevance is different from click-through rate prediction in that no direct training signal is available. Most previous attempts learn relevance models from user click-through data that are cheap and abundant. Unfortunately, click behavior is noisy and misleading, which is affected by not only relevance but also factors including price, image and attractive titles. Therefore, it is challenging but valuable to learn relevance models from click-through data. In this paper, we propose a new relevance learning framework that concentrates on how to train a relevance model from the weak supervision of click-through data. Different from previous efforts that treat samples as either relevant or irrelevant, we construct more fine-grained samples for training. We propose a novel way to consider samples of different relevance confidence, and come up with a new training objective to learn a robust relevance model with desirable score distribution. The proposed model is evaluated on offline annotated data and online A/B testing, and it achieves both promising performance and high computational efficiency. The model has already been deployed online, serving the search traffic of Taobao for over a year.
description: Accepted to TheWebConf/WWW 2021
A Simple Algorithm for Optimal Search Trees with Two-Way Comparisons
Creators: name: Chrobak, Marek
name: Golin, Mordecai
name: Munro, J. Ian
name: Young, Neal E.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: FOS: Computer and information sciences
subject: E.4; G.1.6; G.2.2; H.3.1; I.4.2
subject: 68P10, 68P30, 68W25, 94A45

description: We present a simple $O(n^4)$-time algorithm for computing optimal search trees with two-way comparisons. The only previous solution to this problem, by Anderson et al., has the same running time, but is significantly more complicated and is restricted to the variant where only successful queries are allowed. Our algorithm extends directly to solve the standard full variant of the problem, which also allows unsuccessful queries and for which no polynomial-time algorithm was previously known. The correctness proof of our algorithm relies on a new structural theorem for two-way-comparison search trees.
description: v3 adds Appendix B, with a stronger alternative to Theorem 1
Δημοσιογραφικές Πρακτικές, Επικοινωνιακές Στρατηγικές και Νέα Μέσα Επικοινωνίας για την προβολή και διάδοση αποτελεσμάτων δράσεων και προγραμμάτων Εταιρικής Κοινωνικής Ευθύνης
Creators: name: Γιασιμάκη, Χρυσούλα Οδυσσέα
Publisher: name: Aristotle University of Thessaloniki
Year: 2020
Subjects: Διάδοση
Επικοινωνία
Δράσεις
Dissemination
Communication
Actions

description: Στην παρούσα εργασία εξετάζονται τα προγράμματα κοινωφελών δράσεων οργανισμών, τα προγράμματα ΕΚΕ, οι πρωτοβουλίες και δράσεις ιδρυμάτων, ΜΚΟ καθώς και τα ακαδημαϊκά ερευνητικά προγράμματα. Το κοινό σημείο των προγραμμάτων αυτών είναι η ανάγκη διάδοσης και η επικοινωνία τους με το ευρύ κοινό, με την κοινωνία. Γίνεται αντιληπτό πως μέσα από τα μηνύματα που εκπέμπονται, προάγεται η γνώση, η ευαισθητοποίηση και η αλλαγή στάσης σε πολλά θέματα που μπορούν να βελτιώσουν τη ζωή των ανθρώπων και να οδηγήσουν στη συνοχή της κοινωνίας, την αλλαγή νοοτροπίας, την αλληλεγγύη και την αλληλοκατανόηση.Μέσα από μελέτες περίπτωσης, ανάλυση περιεχομένου και συνεντεύξεις επαγγελματιών του κλάδου, θα επιχειρηθεί η καταγραφή των δημοσιογραφικών πρακτικών και των επικοινωνιακών στρατηγικών μέσω των επικοινωνιακών τεχνολογιών και δικτύων με στόχο να διερευνηθούν οι κυρίαρχες τάσεις, οι καινοτόμες ιδέες και να αναζητηθούν οι δείκτες κοινωνικής επίδρασης και ο τρόπος αξιοποίησης τους.
description: This paper examines the programs of public benefit organizations, CSR programs, initiatives and actions of foundations, NGOs and academic research programs. The common point of these programs is the need to disseminate and communicate them to the general public, to society. It is understood that through the messages transmitted, knowledge, awareness and attitude change are promoted on many issues that can improve people's lives and lead to social cohesion, change of mindset, solidarity and mutual understanding. Case studies, content analysis, and industry interviews will attempt to capture journalistic practices and communication strategies through communication technologies and networks to explore dominant trends, innovative ideas, and search for social indicators and indicators. how to exploit them.
The Virial Balance of Clumps and Cores in Molecular Clouds
Creators: name: Dib, Sami
name: Kim, Jongsoo
name: Vazquez-Semadeni, Enrique
name: Burkert, Andreas
name: Shadmehri, Mohsen
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study the instantaneous virial balance of clumps and cores (CCs) in 3D simulations of driven, MHD, isothermal molecular clouds (MCs). The models represent a range of magnetic field strengths in MCs from subcritical to non-magnetic regimes. We identify CCs at different density thresholds, and for each object, we calculate all the terms that enter the Eulerian form of the virial theorem (EVT). A CC is considered gravitationally bound when the gravitational term in the EVT is larger than the amount for the system to be virialized, which is more stringent than the condition that it be large enough to make the total volume energy negative. We also calculate, quantities commonly used in the observations to indicate the state of gravitational boundedness of CCs such as the Jeans number J_c, the mass-to magnetic flux ratio mu_c, and the virial parameter alpha_vir. Our results show that: a) CCs are dynamical out-of-equilibrium structures. b) The surface energies are of the same order than their volume counterparts c) CCs are either in the process of being compressed or dispersed by the velocity field. Yet, not all CCs that have a compressive net kinetic energy are gravitationally bound. d) There is no 1-to-1 correspondence between the state of gravitational boundedness of a CC as described by the virial analysis or as implied by the classical indicators. In general, in the virial analysis, we observe that only the inner regions of the objects are gravitationally bound, whereas J_c, alpha_vir, and mu_c estimates tend to show that they are more gravitationally bound at the lowest threshold levels and more magnetically supercritical. g) We observe, in the non-magnetic simulation, the existence of a bound core with structural and dynamical properties that resemble those of the Bok globule Barnard 68 (B68).
description: Accepted to ApJ. Discussion substantially enlarged, a few corrections and additional figures. Main conclusions unchanged
Idealised 3D simulations of diabatically-forced Ledoux convection. Application to the atmosphere of hot rocky exoplanets
Creators: name: Daley-Yates, Simon
name: Padioleau, Thomas
name: Tremblin, Pascal
name: Kestener, Pierre
name: Mancip, Martial
Publisher: name: arXiv
Year: 2021
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We investigate the impact on convective numerical simulations of thermo-compositional diabatic processes. We focus our study on simulations with a stabilizing temperature gradient and a destabilizing mean-molecular weight gradient. We aim to establish the possibility for a reduced temperature-gradient in such setups. A suite of 3D simulations were conducted using a numerical hydrodynamic code. We used as a simplified test case, a sample region of the secondary atmosphere of a hot rocky exoplanet within which the chemical transition CO+O $\leftrightarrow$ CO$_{2}$ could occur. Newtonian cooling and a chemical source term was used to maintain a negative mean molecular weight gradient. Our results demonstrate that this setup can reduce the temperature gradient, a result which does not converge away with resolution or over time. We also show that the presence of the reduced temperature gradient is a function of the forcing timescales. The above transition leads to a bifurcation of the temperature profile when the chemical forcing is fast, reminiscent of the bifurcation seen in the boiling crisis for steam/liquid convection. With the reduced temperature gradient in these idealized setups, there exists the possibility for an analogy of the reddening (currently observed in the spectra of brown dwarfs) in the spectra of rocky exoplanet atmospheres. Detailed 1D modelling is needed, in order to characterize the equilibrium thermal and compositional gradients, the timescales, and the impact of a realistic equation of state, in order to assess if the regime identified here will develop in realistic situations. This possibility cannot, however, be excluded a priori. This prediction is new for terrestrial atmospheres and represents strong motivation for the use of diabatic models when analysing atmospheric spectra of rocky exoplanets that will be observed with e.g. the James Webb Space Telescope.
description: 13 pages, 10 figures
On the question of deconfinement in noncommutative Schwinger Model
Creators: name: Saha, Anirban
name: Mukherjee, Pradip
name: Rahaman, Anisur
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The 1+1 dimensional bosonised Schwinger model with a generalized gauge invariant regularisation has been studied in a noncommutative scenario to investigate the fate of the transition from confinement to deconfinement observed in the commutative setting. We show that though the fuzziness of space time introduces new features in the confinement scenario, it does not affect the deconfining limit.
description: 4 pages, revTex
Maximal Diversity and Zipf's Law
Creators: name: Mazzarisi, Onofrio
name: de Azevedo-Lopes, Amanda
name: Arenzon, Jeferson J.
name: Corberi, Federico
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Zipf's law describes the empirical size distribution of the components of many systems in natural and social sciences and humanities. We show, by solving a statistical model, that Zipf's law co-occurs with the maximization of the diversity of the component sizes. The law ruling the increase of such diversity with the total dimension of the system is derived and its relation with Heaps' law is discussed. As an example, we show that our analytical results compare very well with linguistics datasets.
description: 5 pages, 3 figures
Effective thermalization of a many-body dynamically localized Bose gas
Creators: name: Vuatelet, Vincent
name: Rançon, Adam
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Dynamical localization is the analog of Anderson localization in momentum space, where the system's energy saturates and the single-particle wave-functions are exponentially localized in momentum space. In the presence of interactions, in the context of a periodically kicked Bose gas, it has been argued that dynamical localization persists. Focusing on the Tonks (strongly interacting) regime, we show that the many-body dynamically localized phase is effectively thermal, a clear deviation from the breaking of ergodicity observed in standard many-body localized systems. We relate the effective temperature to the driving parameters, and thus quantitatively describe the loss of coherence at large distances in this phase. Contrary to the non-interacting case, the momentum distribution decays as a power-law at large momenta, characterized by an effectively thermal Tan's contact. This is a rare example where driving and many-body (dynamical) localization lead to an effectively ergodic state.
description: v1) 5+7 pages, 4+10 figures; v2) 11 pages, 13 figures. Published version
Is the time lag-luminosity relation of GRBs a consequence of the Amati relation?
Creators: name: Hafizi, Mimoza
name: Mochkovitch, Robert
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The lag-luminosity relation (LLR) provides a way of estimating GRB luminosity by measuring the spectral lags between different energy bands. We want to understand the origin of the LLR and test its validity. This appears especially important if the LLR is to be used as a distance indicator. We perform a linear analysis of the lag between two spectral bands. The lag is obtained as the time interval between the maxima of a given pulse in the two bands. We get a simple expression for the lag, which shows in a very simple way how it is related to the spectral evolution of the burst via the variation of the peak energy and spectral indices. When this expression is coupled to the Amati relation, it leads to a LLR that agrees with the observational results only if the burst's spectral evolution is limited to a decrease in peak energy during pulse decay. However, when the variation of the spectral indices is also taken into account, the predicted LLR differs from the observed one. We briefly discuss some ways to solve this problem, such as a possible correlation between pulse spikiness and burst luminosity.
description: Accepted for publication in Astronomy & Astrophysics, 5 pages, 3 figures
An automated vision system for detection and counting of uneaten food pellets in a fish sea cage
Creators: name: Foster, Michael D.
Publisher: name: University of British Columbia
Year: 2008

description: A system which quantifies the number of food pellets eaten by salmon in a sea cage would be beneficial to both fish farmers, and researchers. Such a system could be used for reducing food wastage, determining time-related feeding patterns, ensuring fish receive the correct dosage of drugs, etc. We developed algorithms for detection and counting of food pellets from recorded video image sequences, which could be used to determine actual feeding rates in a sea cage. The number of food pellets eaten over time is determined by counting the number of pellets not eaten. The method involves counting the number of pellets of a known size, falling through the view area of an underwater video camera. The size of the view area of the camera varies with the size of the food pellets used. The pellets, which appear white underwater, are counted as they enter the view area of the underwater camera, and are tracked in this area to avoid recounting. For each video frame in the sequence, image preprocessing is done, followed by object detection, object classification, and object tracking and counting. Original algorithms were developed for this project to automatically threshold images, track objects in consecutive frames, and count the objects entering the view area of the camera. The algorithms were implemented on a personal computer based image processing system. Experiments were carried out to test the algorithms with pellet densities used in actual feeding situations. The utility of the algorithms was confirmed by the experimental results. The average count error for the tests performed was approximately +/-10%. The recommended improvements to the counting algorithms should significantly reduce this error.
Accretion-powered Millisecond Pulsar Outbursts
Creators: name: Galloway, Duncan K.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The population of accretion-powered millisecond pulsars has grown rapidly over the last four years, with the discovery of six new examples to bring the total sample to seven. While the first six discovered are transients active for a few weeks every two or more years, the most recently-discovered source HETE J1900.1-2455, has been active for more than 8 months. We summarise the transient behaviour of the population to estimate long-term time-averaged fluxes, and equate these fluxes to the expected mass transfer rate driven by gravitational radiation in order to constrain the distances. We also estimate an upper limit of 6 kpc to the distance of IGR J00291+5934 based on the non-detection of bursts from this source.
description: 5 pages, 2 figures, to be published in: "The Transient Milky Way: a perspective for MIRAX", eds. F. D'Amico, J. Braga & R. Rothschild, AIP Conf. Proc
Agent-based modeling of COVID-19 outbreaks for New York state, UK and Novosibirsk region
Creators: name: Krivorotko, Olga
name: Sosnovskaia, Mariia
name: Vashchenko, Ivan
name: Kerr, Cliff
name: Lesnic, Daniel
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optimization and Control (math.OC)
subject: Dynamical Systems (math.DS)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Mathematics
subject: FOS: Biological sciences
subject: G.1.6; G.3; G.4
subject: 91B69, 92D30, 65K10

description: This paper uses Covasim, an agent-based model (ABM) of COVID-19, to evaluate and scenarios of epidemic spread in New York State (USA), the UK, and the Novosibirsk region (Russia). Epidemiological parameters such as contagiousness (virus transmission rate), initial number of infected people, and probability of being tested depend on the region's demographic and geographical features, the containment measures introduced; they are calibrated to data about COVID-19 spread in the region of interest. At the first stage of our study, epidemiological data (numbers of people tested, diagnoses, critical cases, hospitalizations, and deaths) for each of the mentioned regions were analyzed. The data were characterized in terms of seasonality, stationarity, and dependency spaces, and were extrapolated using machine learning techniques to specify unknown epidemiological parameters of the model. At the second stage, the Optuna optimizer based on the tree Parzen estimation method for objective function minimization was applied to determine the model's unknown parameters. The model was validated with the historical data of 2020. The modeled results of COVID-19 spread in New York State, the UK and the Novosibirsk region have demonstrated that if the level of testing and containment measures is preserved, the number of positive cases in New York State and the Novosibirsk region will remain the same during March of 2021, while in the UK it will reduce. Due to the features of the data for the Novosibirsk region (two datasets are characterized as stationary series with probability of 1), the forecast precision is relatively high for the number of hospitalizations, but is lower for new cases of COVID-19.
description: 48 pages, 27 figures
The Quantum Gravity Disk: Discrete Current Algebra
Creators: name: Freidel, Laurent
name: Goeller, Christophe
name: Livine, Etera R.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study the quantization of the corner symmetry algebra of 3d gravity, that is the algebra of observables associated with 1d spatial boundaries. In the continuum field theory, at the classical level, this symmetry algebra is given by the central extension of the Poincaré loop algebra. At the quantum level, we construct a discrete current algebra based on a quantum symmetry group given by the Drinfeld double $\mathcal{D}\mathrm{SU}(2)$. Those discrete currents depend on an integer $N$, a discreteness parameter, understood as the number of quanta of geometry on the 1d boundary: low $N$ is the deep quantum regime, while large $N$ should lead back to a continuum picture. We show that this algebra satisfies two fundamental properties. First, it is compatible with the quantum space-time picture given by the Ponzano-Regge state-sum model, which provides discrete path integral amplitudes for 3d quantum gravity. The integer $N$ then counts the flux lines attached to the boundary. Second, we analyse the refinement, coarse-graining and fusion processes as $N$ changes, and we show that the $N\rightarrow\infty$ limit is a classical limit where we recover the Poincaré current algebra. Identifying such a discrete current algebra on quantum boundaries is an important step towards understanding how conformal field theories arise on spatial boundaries in quantized space-times such as in loop quantum gravity.
description: 42 pages, v2: re-organized content, accepted for publication in Journal of Mathematical Physics
Simulations of Sisyphus cooling including multiple excited states
Creators: name: Svensson, F.
name: Jonsell, S.
name: Dion, C. M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We extend the theory for laser cooling in a near-resonant optical lattice to include multiple excited hyperfine states. Simulations are performed treating the external degrees of freedom of the atom, i.e., position and momentum, classically, while the internal atomic states are treated quantum mechanically, allowing for arbitrary superpositions. Whereas theoretical treatments including only a single excited hyperfine state predict that the temperature should be a function of lattice depth only, except close to resonance, experiments have shown that the minimum temperature achieved depends also on the detuning from resonance of the lattice light. Our results resolve this discrepancy.
description: 7 pages, 6 figures
Comment on "Large negative lateral shifts from the Kretschmann-Raether configuration with left-handed materials" Appl. Phys. Lett. 87, 221102, 2005
Creators: name: Moreau, Antoine
name: Felbacq, Didier
Publisher: name: arXiv
Year: 2007
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: The negative shifts seen by Wang and Zhu are not due to the excitation of surface plasmons but to leaky modes of the slab propagating backward. Provided the characteristics of the LHM slab are chosen correctly, it is shown that a leaky surface plasmon can actually be excited using the KR configuration.
description: Accept\'{e} pour publication
A Granular Brownian Ratchet Model
Creators: name: Costantini, Giulio
name: Marconi, Umberto Marini Bettolo
name: Puglisi, Andrea
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We show by numerical simulations that a non rotationally symmetric body, whose orientation is fixed and whose center of mass can only slide along a rectilinear guide, under the effect of inelastic collisions with a surrounding gas of particles, displays directed motion. We present a theory which explains how the lack of time reversal induced by the inelasticity of collisions can be exploited to generate a steady average drift. In the limit of an heavy ratchet, we derive an effective Langevin equation whose parameters depend on the microscopic properties of the system and obtain a fairly good quantitative agreement between the theoretical predictions and simulations concerning mobility, diffusivity and average velocity.
description: 4 pages, 4 figures, submitted for publication
Zero-bias anomaly in the tunneling density of states of graphene
Creators: name: Mariani, Eros
name: Glazman, Leonid I.
name: Kamenev, Alex
name: von Oppen, Felix
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: In the vicinity of the Fermi energy, the band structure of graphene is well described by a Dirac equation. Impurities will generally induce both a scalar potential as well as a (fictitious) gauge field acting on the Dirac fermions. We show that the angular dependence of the zero-bias anomaly in the spatially resolved tunneling density of states (TDOS) around a particular impurity allows one to distinguish between these two contributions. Our predictions can be tested in scanning-tunneling-microscopy measurements on graphene.
description: 4 pages, 3 figures
Η Λογική της Ηλιακής Μεταφυσικής στην ποιητική του Ελύτη. «Άξιον Εστί»: Ανοίγω το στόμα μου, Ένα το χελιδόνι
Creators: name: Παπαμόσχου, Γεωργία-Σταυριάνα Ηλία
Publisher: name: Aristotle University of Thessaloniki
Year: 2020
Subjects: Ελύτης
Μεταφυσική
Ποιητική Πραγματικότητα
Elytis
Metaphysics
Poetic Reality

description: Στην παρούσα εργασία επιχειρείται να οριοθετηθεί η σχέση του Ελύτη με τη φιλοσοφία, η οποία παρά το γεγονός ότι συνήθως θεωρείται δεδομένη, δεν έχει γίνει αντικείμενο συστηματικής μελέτης, ενώ θεωρώ πως η ενασχόληση των περισσοτέρων σχολιαστών με τον Ελύτη ως ποιητικό φαινόμενο, έχει εξαντληθεί. Συγκεκριμένα το θέμα που πραγματεύεται η εργασία τούτη, είναι η εξέταση του μεταφυσικού ποιητικού σύμπαντος, όπως αντανακλάται σε ολόκληρο το έργο του ποιητή και η σύνδεση αυτής της μεταφυσικής φιλοσοφικής πραγματικότητας με το «ηλιακό φως» και την εξωτερική πραγματικότητα των αισθητών πραγμάτων. Σκοπός είναι να εντοπιστεί και να εξηγηθεί ο τρόπος με τον οποίο ο Ελύτης ενέταξε στο έργο του το «φιλοσοφειν», το πώς αυτό παρουσιάζεται στους αναγνώστες του, καθώς και να ερευνηθεί η ιδιάζουσα λογική που διέπει το ποιητικό σύμπαν και τις μορφές του. Εν κατακλείδι, να καταφέρει να καταστεί σαφής ο ρόλος, τόσο της φιλοσοφίας, όσο και του βαθειά φιλοσοφικού και μεταφυσικού φωτός στα ποιητικά έργα του.
description: The present paper attempts to delineate Elytis's relation to philosophy, which, although usually considered a given, has not been systematically studied, and I find that most critics’ involvement with Elytis solely as a poetic phenomenon has already been exhausted. In particular, the subject of the present paper is the examination of the metaphysical poetic universe, as reflected throughout the poet's work, and the relation of this metaphysical philosophical reality to the "sunlight" and the external reality of material objects perceived by the senses. The aim is to identify and explain how Elytis incorporated the element of "philosophein" (philosophising) in his work, how this is presented to his readers, and to investigate the unique logic permeating the poetic universe and its forms. In conclusion, an attempt will be made to clarify the role of both philosophy and the deeply philosophical and metaphysical light in his poetic works.
Filling contours on the linear quadtree domain by insertion and traversal
Creators: name: Wilke, Lars Martin
Publisher: name: University of British Columbia
Year: 2009

description: An algorithm is presented which fills contours described by a set of pixels whose locations are given in unsorted linear quadtree (LQT) form. Each pixel requires an associated blocking code which indicates locally in which direction the region should grow. The technique takes advantage of certain characteristics of LQT location codes to determine if the boundary pixels fall on the edges or vertices of lower resolution LQT cells. This information allows for the automatic determination of boundary cells after the pixels have been inserted into a regular quadtree. Remaining uncoloured cells are coloured using conventional techniques. The algorithm compares favourably with existing LQT filling algorithms both in time and space complexity. The technique avoids explicit sorting of the input pixels or output cells by location code, and no condensation of cells is required. Traversing the regular quadtree in preorder generates the sorted output cells as an LQT.
Analysis Method for Jet-Like Three-Particle Azimuthal Correlations
Creators: name: Ulery, Jason G.
name: Wang, Fuqiang
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Jet-like three-particle azimuthal correlations can discriminate various physical scenarios that have been proposed to explain the observed strong modification to two-particle azimuthal correlations. The three-particle correlation analysis is notoriously difficult in heavy-ion collisions due to the large combinatoric backgrounds. We describe the general idea behind the jet-like three-particle azimuthal correlation analysis, with emphasis put on the subtraction of the combinatoric backgrounds. We discuss in detail the various systematic effects in such an analysis.
description: This is the final published version in NIM A
Extremal statistics for stochastic resetting systems
Creators: name: Singh, Prashant
name: Pal, Arnab
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: While averages and typical fluctuations often play a major role to understand the behavior of a non-equilibrium system, this nonetheless is not always true. Rare events and large fluctuations are also pivotal when a thorough analysis of the system is being done. In this context, the statistics of extreme fluctuations in contrast to the average plays an important role, as has been discussed in fields ranging from statistical and mathematical physics to climate, finance and ecology. Herein, we study Extreme Value Statistics (EVS) of stochastic resetting systems which have recently gained lot of interests due to its ubiquitous and enriching applications in physics, chemistry, queuing theory, search processes and computer science. We present a detailed analysis for the finite and large time statistics of extremals (maximum and arg-maximum i.e., the time when the maximum is reached) of the spatial displacement in such system. In particular, we derive an exact renewal formula that relates the joint distribution of maximum and arg-maximum of the reset process to the statistical measures of the underlying process. Benchmarking our results for the maximum of a reset-trajectory that pertain to the Gumbel class for large sample size, we show that the arg-maximum density attains to a uniform distribution regardless of the underlying process at a large observation time. This emerges as a manifestation of the renewal property of the resetting mechanism. The results are augmented with a wide spectrum of Markov and non-Markov stochastic processes under resetting namely simple diffusion, diffusion with drift, Ornstein-Uhlenbeck process and random acceleration process in one dimension. Rigorous results are presented for the first two set-ups while the latter two are supported with heuristic and numerical analysis.
description: 23 pages, 8 figures
title: Albaricoquero Japonés :
title: Directrices para la ejecución del examen de la distinción, la homogeneidad y la estabilidad.
titleType: Subtitle
Creators: name: International Union For The Protection Of New Varieties Of Plants,
Publisher: name: International Union for the Protection of New Varieties of Plants,
Year: 0
Subjects: Mume
Group identity.
New Varieties of Plants

description: La finalidad de estas directrices (“directrices de examen”) es elaborar los principios que figuran en la Introducción General (documento TG/1/3) y sus documentos TGP conexos, con objeto de que sirvan de orientación práctica y detallada para el examen armonizado de la distinción, homogeneidad y estabilidad (DHE) y en particular, para identificar los caracteres apropiados para el examen DHE y producir descripciones armonizadas de variedades.