cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Models of AM CVn star outbursts
Creators: name: Kotko, Iwona
name: Lasota, Jean-Pierre
name: Dubus, Guillaume
name: Hameury, Jean-Marie
Publisher: name: arXiv
Year: 2012
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Outbursting AM CVn stars exhibit outbursts similar to those observed in different types of dwarf novae. Their light-curves combine the characteristic features of SU UMa, ER UMa, Z Cam, and WZ Sge-type systems but also show a variety of properties never observed in dwarf novae. The compactness of AM CVn orbits and their unusual chemical composition make these systems valuable testbeds for outburst models. We aim for a better understanding of the role of helium in the accretion disc instability mechanism, testing the model for dwarf novae outbursts in the case of AM CVn stars, and aim to explain the outburst light-curves of these ultra-compact binaries. We calculated the properties of the hydrogen-free AM CVn stars using our previously developed numerical code adapted to the different chemical composition of these systems and supplemented with formulae accounting for mass transfer rate variations, additional sources of the disc heating, and the primary's magnetic field. We discovered how helium-dominated discs react to the thermal-viscous instability and were able to reproduce various features of the outburst cycles in the light-curves of AM CVn stars. The AM CVn outbursts can be explained by the suitably adapted dwarf-nova disc instability model but, as in the case of its application to hydrogen-dominated cataclysmic variables, one has to resort to additional mechanisms to account for the observed superoutbursts, dips, cycling states, and standstills. We show that the enhanced mass-transfer rate, due presumably to variable irradiation of the secondary, must not only be taken into account but is a determining factor that shapes AM CVn star outbursts. The cause of the variable secondary's irradiation has yet to be understood; the best candidate is the precession of a tilted/warped disc.
description: Astronomy and Astrophysics - in press; corrected (language) version
Two dimensional vertex-decorated Lieb lattice with exact mobility edges and robust flat bands
Creators: name: Wang, Yucheng
name: Zhang, Long
name: Wan, Yuhao
name: He, Yu
name: Wang, Yongjian
Publisher: name: arXiv
Year: 2022
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The mobility edge (ME) that marks the energy separating extended and localized states is a central concept in understanding the metal-insulator transition induced by disordered or quasiperiodic potentials. MEs have been extensively studied in three dimensional disorder systems and one-dimensional quasiperiodic systems. However, the studies of MEs in two dimensional (2D) systems are rare. Here we propose a class of 2D vertex-decorated Lieb lattice models with quasiperiodic potentials only acting on the vertices of a (extended) Lieb lattice. By mapping these models to the 2D Aubry-André model, we obtain exact expressions of MEs and the localization lengths of localized states, and further demonstrate that the flat bands remain unaffected by the quasiperiodic potentials. Finally, we propose a highly feasible scheme to experimentally realize our model in a quantum dot array. Our results open the door to studying and realizing exact MEs and robust flat bands in 2D systems.
Start Small: Training Controllable Game Level Generators without Training Data by Learning at Multiple Sizes
Creators: name: Zakaria, Yahia
name: Fayek, Magda
name: Hadhoud, Mayada
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: A level generator is a tool that generates game levels from noise. Training a generator without a dataset suffers from feedback sparsity, since it is unlikely to generate a playable level via random exploration. A common solution is shaped rewards, which guides the generator to achieve subgoals towards level playability, but they consume effort to design and require game-specific domain knowledge. This paper proposes a novel approach to train generators without datasets or shaped rewards by learning at multiple level sizes starting from small sizes and up to the desired sizes. The denser feedback at small sizes negates the need for shaped rewards. Additionally, the generators learn to build levels at various sizes, including sizes they were not trained for. We apply our approach to train recurrent auto-regressive generative flow networks (GFlowNets) for controllable level generation. We also adapt diversity sampling to be compatible with GFlowNets. The results show that our generators create diverse playable levels at various sizes for Sokoban, Zelda, and Danger Dave. When compared with controllable reinforcement learning level generators for Sokoban, the results show that our generators achieve better controllability and competitive diversity, while being 9x faster at training and level generation.
description: 26 pages, 7 tables, 7 figures. Code: https://github.com/yahiaetman/ms-level-gen
Coulomb focusing at above-threshold ionization in elliptically polarized mid-infrared strong laser fields
Creators: name: Liu, Chengpu
name: Hatsagortsyan, Karen Z.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: The role of Coulomb focusing in above-threshold ionization in an elliptically polarized mid-infrared strong laser field is investigated within a semiclassical model incorporating tunneling and Coulomb field effects. It is shown that Coulomb focusing up to moderate ellipticity values is dominated by multiple forward scattering of the ionized electron by the atomic core that creates a characteristic low-energy structure in the photoelectron spectrum and is responsible for the peculiar energy scaling of the ionization normalized yield along the major polarization axis. At higher ellipticities, the electron continuum dynamics is disturbed by the Coulomb field effect mostly at the exit of the ionization tunnel. Due to the latter, the normalized yield is found to be enhanced, with the enhancement factor being sharply pronounced at intermediate ellipticities.
Sensitivity of neutron to proton ratio toward the high density behavior of symmetry energy in heavy-ion collisions
Creators: name: Kumar, S.
name: Ma, Y. G.
name: Zhang, G. Q.
name: Zhou, C. L.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The symmetry energy at sub and supra-saturation densities has a great importance in understanding the exact nature of asymmetric nuclear matter as well as neutron star, but, it is poor known, especially at supra-saturation densities. We will demonstrate here that the neutron to proton ratios from different kind of fragments is able to determine the supra-saturation behavior of symmetry energy or not. For this purpose, a series of Sn isotopes are simulated at different incident energies using the Isospin Quantum Molecular Dynamics (IQMD) model with either a soft or a stiff symmetry energy for the present study. It is found that the single neutron to proton ratio from free nucleons as well as LCP's is sensitive towards the symmetry energy, incident energy as well as isospin asymmetry of the system. However, with the double neutron to proton ratio, it is true only for the free nucleons. It is possible to study the high density behavior of symmetry energy by using the neutron to proton ratio from free nucleons.
description: 11 Pages, 9 Figures
First Order Dynamic Sliding Mode Control of a Wind Turbine with Optimized Tip Speed Ratio
Creators: name: Padmanabhuni, Nishanth
Publisher: name: Graduate Studies
Year: 2023
Subjects: subject: Wind turbines
subject: Renewable energy
subject: Robust Control
subject: Engineering--Mechanical

description: This thesis explores a novel sliding mode control method to boost power from wind turbines, focusing on the power optimization region. The controller, designed for a 3rd-order system with generator torque input and rotor torque disturbance, is tested using a simple wind turbine model and FAST for validation. The first objective is to identify the optimal tip-speed-ratio (TSR) for maximum power using the Recursive Least Squares (RLS) method. The RLS generates a polynomial connecting the TSR and power coefficient, defining the wind turbine's operating point. A forgetting factor is incorporated in the RLS method for system adaptability to changing conditions. The other objective utilizes a first-order dynamic sliding mode controller with integration (FODSMCI) to control the wind turbine, keeping it at the optimal TSR for maximum power without chattering. The study revealed the RLS's effectiveness in determining optimal TSR on wind turbine models. The FODSMCI enables a balance between controller performance and rotor speed tracking, yielding a chatter-free response.
title: (IM/E)MIGRATION
Creators: name: Laffer, Alexander
Publisher: name: The Digital Review
Year: 2021

description: Motivated by research into empathy, the ongoing global displacement of people and the author’s own family history of migration, (IM/E)MIGRATION is a set of 7.9 billion multimodal visual narratives generated through the random combination of three key elements: background image (setting), portrait (character) and text (action). Within the text, markers of identity and location and other linguistic features that interact with empathy (e.g., pronouns and metaphor) are also randomised. The shifting combination of components subverts expected responses to narratives of migration, problematises the relationship between literary and social empathy, and encourages the reader to reflect on their capacity to empathise. By presenting a set of narratives beyond the capacity of any reader to complete, readers are encouraged to take a critical stance and consider the structural elements that influence our (in)ability to empathise.
Additional file 9 of Small RNA profiling for identification of microRNAs involved in regulation of seed development and lipid biosynthesis in yellowhorn
Creators: name: Wang, Li
name: Ruan, Chengjiang
name: Bao, Aomin
name: Li, He
Publisher: name: figshare
Year: 2021
Subjects: subject: Genetics
subject: FOS: Biological sciences

description: Additional file 9: Table S9. Identified candidate targets for partial known and novel miRNAs.
On the hyperbolicity of surfaces of general type with small $c_1 ^2$
Creators: name: Roulleau, Xavier
name: Rousseau, Erwan
Publisher: name: arXiv
Year: 2012
Subjects: subject: Algebraic Geometry (math.AG)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics

description: Surfaces of general type with positive second Segre number $s_2:=c_1^2-c_2>0$ are known by results of Bogomolov to be quasi-hyperbolic i.e. with finitely many rational and elliptic curves. These results were extended by McQuillan in his proof of the Green-Griffiths conjecture for entire curves on such surfaces. In this work, we study hyperbolic properties of minimal surfaces of general type with minimal $c_1^2$, known as Horikawa surfaces. In principle these surfaces should be the most difficult case for the above conjecture as illustrate the quintic surfaces in $\bP^3$. Using orbifold techniques, we exhibit infinitely many irreducible components of the moduli of Horikawa surfaces whose very generic member has no rational curves or even is algebraically hyperbolic. Moreover, we construct explicit examples of algebraically hyperbolic and (quasi-)hyperbolic orbifold Horikawa surfaces.
description: 25 pages; final version to appear in J. Lond. Math. Soc
The CMB and the measure of the multiverse
Creators: name: Salem, Michael P.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In the context of eternal inflation, cosmological predictions depend on the choice of measure to regulate the diverging spacetime volume. The spectrum of inflationary perturbations is no exception, as we demonstrate by comparing the predictions of the fat geodesic and causal patch measures. To highlight the effect of the measure---as opposed to any effects related to a possible landscape of vacua---we take the cosmological model, including the model of inflation, to be fixed. We also condition on the average CMB temperature accompanying the measurement. Both measures predict a 1-point expectation value for the gauge-invariant Newtonian potential, which takes the form of a (scale-dependent) monopole, in addition to a related contribution to the 3-point correlation function, with the detailed form of these quantities differing between the measures. However, for both measures both effects are well within cosmic variance. Our results make clear the theoretical relevance of the measure, and at the same time validate the standard inflationary predictions in the context of eternal inflation.
description: 28 pages; v2: reference added, some clarifications
Critical temperature of a Rashba spin-orbit coupled Bose gas in harmonic traps
Creators: name: Hu, Hui
name: Liu, Xia-Ji
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate theoretically Bose-Einstein condensation of an ideal, trapped Bose gas in the presence of Rashba spin-orbit coupling. Analytic results for the critical temperature and condensate fraction are derived, based on a semi-classical approximation to the single-particle energy spectrum and density of states, and are compared with exact results obtained by explicitly summing discrete energy levels for small number of particles. We find a significant decrease of the critical temperature and of the condensate fraction due to a finite spin-orbit coupling. For large coupling strength and finite number of particles $N$, the critical temperature scales as $N^{2/5}$ and $N^{2/3}$ in three and two dimensions, respectively, contrasted to the predictions of $N^{1/3}$ and $N^{1/2}$ in the absence of spin-orbit coupling. Finite size corrections in three dimensions are also discussed.
description: 9 pages and 8 figures; published version in Physical Review A
Template-directed protein misfolding in neurodegenerative disease
Creators: name: Guest, William Clay
Publisher: name: University of British Columbia
Year: 2012

description: Protein misfolding diseases represent a large burden to human health for which only symptomatic treatment is generally available. These diseases, such as Creutzfeldt-Jakob disease, amyotrophic lateral sclerosis, and the systemic amyloidoses, are characterized by conversion of globular, nativelyfolded proteins into pathologic β-sheet rich protein aggregates deposited in affected tissues. Understanding the thermodynamic and kinetic details of protein misfolding on a molecular level depends on accurately appraising the free energies of the folded, partially unfolded intermediate, and misfolded protein conformers. There are multiple energetic and entropic contributions to the total free energy, including nonpolar, electrostatic, solvation, and configurational terms. To accurately assess the electrostatic contribution, a method to calculate the spatially-varying dielectric constant in a protein/water system was developed using a generalization of Kirkwood Frohlich theory along with brief all-atom molecular dynamics simulations. This method was combined with previously validated models for nonpolar solvation and configurational entropy in an algorithm to calculate the free energy change on partial unfolding of contiguous protein subsequences. Results were compared with those from a minimal, topologically-based Gō model and direct calculation of free energies by steered all-atom molecular dynamics simulations. This algorithm was applied to understand the early steps in the misfolding mechanism for β₂-microglobulin, prion protein, and superoxide dismutase 1 (SOD1). It was hypothesized that SOD1 misfolding may follow a template-directed mechanism like that discovered previously for prion protein, so misfolding of SOD1 was induced in cell culture by transfection with mutant SOD1 constructs and observed to stably propagate intracellularly and intercellularly much like an infectious prion. A defined minimal assay with recombinant SOD protein demonstrated the sufficiency of mutant SOD1 alone to trigger wtSOD1 misfolding, reminiscent of the “protein-only” hypothesis of prion spread. Finally, protein misfolding as a feature of disease may extend beyond neurodegeneration and amyloid formation to cancer, in which derangement of protein folding quality control may lead to antibodyrecognizable misfolded protein present selectively on cancer cell surfaces. The evidence for this hypothesis and possible therapeutic targets are discussed as a future direction.
The Sloan Digital Sky Survey Quasar Lens Search. VI. Constraints on Dark Energy and the Evolution of Massive Galaxies
Creators: name: Oguri, Masamune
name: Inada, Naohisa
name: Strauss, Michael A.
name: Kochanek, Christopher S.
name: Kayo, Issha
name: Shin, Min-Su
name: Morokuma, Tomoki
name: Richards, Gordon T.
name: Rusu, Cristian E.
name: Frieman, Joshua A.
name: Fukugita, Masataka
name: Schneider, Donald P.
name: York, Donald G.
name: Bahcall, Neta A.
name: White, Richard L.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present a statistical analysis of the final lens sample from the Sloan Digital Sky Survey Quasar Lens Search (SQLS). The number distribution of a complete subsample of 19 lensed quasars selected from 50,836 source quasars is compared with theoretical expectations, with particular attention to the selection function. Assuming that the velocity function of galaxies does not evolve with redshift, the SQLS sample constrains the cosmological constant to Ω_Λ=0.79^{+0.06}_{-0.07}(stat.)^{+0.06}_{-0.06}(syst.) for a flat universe. The dark energy equation of state is found to be consistent with w=-1 when the SQLS is combined with constraints from baryon acoustic oscillation (BAO) measurements or results from the Wilkinson Microwave Anisotropy Probe (WMAP). We also obtain simultaneous constraints on cosmological parameters and redshift evolution of the galaxy velocity function, finding no evidence for redshift evolution at z<1 in any combinations of constraints. For instance, number density evolution quantified as ν_n=d\lnϕ_*/d\ln(1+z) and the velocity dispersion evolution ν_σ=d\lnσ_*/d\ln(1+z) are constrained to ν_n=1.06^{+1.36}_{-1.39}(stat.)^{+0.33}_{-0.64}(syst.) and ν_σ=-0.05^{+0.19}_{-0.16}(stat.)^{+0.03}_{-0.03}(syst.) respectively when the SQLS result is combined with BAO and WMAP for flat models with a cosmological constant. We find that a significant amount of dark energy is preferred even after fully marginalizing over the galaxy evolution parameters. Thus the statistics of lensed quasars robustly confirm the accelerated cosmic expansion.
description: 44 pages, 12 figures, 4 tables, accepted for publication in AJ
Towards anisotropic cosmology in group field theory
Creators: name: Calcinari, Andrea
name: Gielen, Steffen
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In cosmological group field theory (GFT) models for quantum gravity coupled to a massless scalar field the total volume, seen as a function of the scalar field, follows the classical Friedmann dynamics of a flat Friedmann-Lemaître-Robertson-Walker (FLRW) Universe at low energies while resolving the Big Bang singularity at high energies. An open question is how to generalise these results to other homogeneous cosmologies. Here we take the first steps towards studying anisotropic Bianchi models in GFT, based on the introduction of a new anisotropy observable analogous to the $β$ variables in Misner's parametrisation. In a classical Bianchi I spacetime, $β$ behaves as a massless scalar field and can be used as a (gravitational) relational clock. We construct a GFT model for which in an expanding Universe $β$ initially behaves like its classical analogue before "decaying" showing a previously studied isotropisation. We support numerical results in GFT by analytical approximations in a toy model. One possible outcome of our work is a definition of relational dynamics in GFT that does not require matter.
description: 40 pages, 14 figures
Integrated Geomechanics and Multiporosity Reservoir Simulation: Investigating Improved Oil Recovery by Huff-and-Puff Gas Injection in Shale Petroleum Reservoirs
Creators: name: Fragoso Amaya, Alfonso Rafael
Publisher: name: Graduate Studies
Year: 2023
Subjects: subject: Geomechanics
subject: Shale Reservoirs
subject: Improved Oil Recovery
subject: Huff-and-Puff
subject: Gas Injection
subject: Reservoir Simulation
subject: Refracturing
subject: Unconventional Reservoirs
subject: Coupling
subject: Rock Mechanics
subject: Adsorption
subject: Diffusion
subject: Numerical Simulation
subject: Finite Elements
subject: Finite Differences
subject: Multiporosity
subject: Huff and Puff
subject: Engineering
subject: Engineering--Petroleum

description: In shale formations, multiple stress-dependent porosity systems coexist, and fluid flow occurs through several processes that are also affected by rock deformation. This multiporosity, multitransport mechanisms and stress-dependent nature of shale reservoirs must be honored when modeling them. Thus, the objective of this dissertation is to develop an integrated numerical simulator of fluid flow and geomechanics that incorporates several storage and transport mechanisms of shale reservoirs and how they are affected by rock deformation. At the same time, this work investigates huff-and-puff gas injection to improve oil recoveries, which is one of the main challenges of shale play exploitation. This thesis attains these goals by: Introducing a methodology that integrates calculation of stresses and deformation of the fractured porous medium; changes in matrix (organic and inorganic) porosities and permeabilities, and fractures (natural and hydraulic) permeabilities; and their effect on production performance of shale reservoirs by primary recovery and huff-and-puff gas injection. Building a coupled geomechanics-fluid flow model that implements the methodology described above. History matching a huff-and-puff pilot well in the Eagle Ford Shale using multiporosity reservoir simulation and investigating the effect of adsorption and diffusion from solid kerogen. Carrying out a history match of data from a huff-and-puff pilot well in the Eagle Ford Shale using a commercial reservoir simulator and investigating several scenarios with the tuned model. Evaluating possible combinations of huff-and-puff gas injection and hydraulic refracturing to improve oil recoveries in shale reservoirs. It is concluded that the integrated multiporosity, multitransport mechanisms and stress-dependent model developed in this thesis properly evaluates changes that occur in the various porosities and permeabilities, and transport mechanisms in shales during primary production and huff-and-puff gas injection.
Physical, Mechanical and Elastic Properties of Chondrite Lithologies
Creators: name: Ciceri, Fabio
Publisher: name: Graduate Studies
Year: 2023
Subjects: subject: Meteorite
subject: Mechanical Properties
subject: Education--Sciences

description: This project measured the physical, mechanical, and elastic properties of a range of chondrite lithologies, a domain that was inadequately explored. The properties measured are porosity, bulk and grain density, seismic velocity (P and S waves), Unconfined Compressive Strength, Direct Shear Strength, Hardness (HLD)/Coefficient of Restitution, dynamic elastic moduli (Young’s modulus, Shear modulus, Bulk modulus, Poisson’s ratio), Static Young’s Modulus, Proportional Limit, and Elemental Compositions. The complexity of measuring these properties accurately in small samples (ranging from 2.5 mm to 2 cm) is underscored, particularly due to the inherent weakness of some lithologies. Innovative adaptations of established methodologies, as elaborated in the Methods chapter, have been implemented to overcome these challenges and conform to ASTM International Standards. Concurrently, this study seeks to encourage the adoption of measuring standards within the planetary science community, fostering improved data cross-referencing and contextual interpretation of future asteroid samples. This study also examined correlations among meteorite properties, with the potential to predict properties that would normally require destructive testing. This study provides a database, contributing to an enhanced grasp of the deformational characteristics exhibited by meteorites and asteroids. This knowledge advancement facilitates modeling of asteroid geology and internal structures.
A Hierarchical Grouping Algorithm for the Multi-Vehicle Dial-a-Ride Problem
Creators: name: Luo, Kelin
name: Florio, Alexandre M.
name: Das, Syamantak
name: Guo, Xiangyu
Publisher: name: arXiv
Year: 2022
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: FOS: Computer and information sciences

description: Ride-sharing is an essential aspect of modern urban mobility. In this paper, we consider a classical problem in ride-sharing - the Multi-Vehicle Dial-a-Ride Problem (Multi-Vehicle DaRP). Given a fleet of vehicles with a fixed capacity stationed at various locations and a set of ride requests specified by origins and destinations, the goal is to serve all requests such that no vehicle is assigned more passengers than its capacity at any point along its trip. We propose an algorithm HRA, which is the first non-trivial approximation algorithm for the Multi-Vehicle DaRP. The main technical contribution is to reduce the Multi-Vehicle DaRP to a certain capacitated partitioning problem, which we solve using a novel hierarchical grouping algorithm. Experimental results show that the vehicle routes produced by our algorithm not only exhibit less total travel distance compared to state-of-the-art baselines, but also enjoy a small in-transit latency, which crucially relates to riders' traveling times. This suggests that HRA enhances rider experience while being energy-efficient.
From Smile Asymptotics to Market Risk Measures
Creators: name: Sircar, Ronnie
name: Sturm, Stephan
Publisher: name: arXiv
Year: 2011
Subjects: subject: Risk Management (q-fin.RM)
subject: Probability (math.PR)
subject: General Finance (q-fin.GN)
subject: FOS: Economics and business
subject: FOS: Mathematics
subject: 91G20, 91G80, 60H30

description: The left tail of the implied volatility skew, coming from quotes on out-of-the-money put options, can be thought to reflect the market's assessment of the risk of a huge drop in stock prices. We analyze how this market information can be integrated into the theoretical framework of convex monetary measures of risk. In particular, we make use of indifference pricing by dynamic convex risk measures, which are given as solutions of backward stochastic differential equations (BSDEs), to establish a link between these two approaches to risk measurement. We derive a characterization of the implied volatility in terms of the solution of a nonlinear PDE and provide a small time-to-maturity expansion and numerical solutions. This procedure allows to choose convex risk measures in a conveniently parametrized class, distorted entropic dynamic risk measures, which we introduce here, such that the asymptotic volatility skew under indifference pricing can be matched with the market skew. We demonstrate this in a calibration exercise to market implied volatility data.
description: 24 pages, 4 figures
Renyi Entropies for Free Field Theories
Creators: name: Klebanov, Igor R.
name: Pufu, Silviu S.
name: Sachdev, Subir
name: Safdi, Benjamin R.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Renyi entropies S_q are useful measures of quantum entanglement; they can be calculated from traces of the reduced density matrix raised to power q, with q>=0. For (d+1)-dimensional conformal field theories, the Renyi entropies across S^{d-1} may be extracted from the thermal partition functions of these theories on either (d+1)-dimensional de Sitter space or R x H^d, where H^d is the d-dimensional hyperbolic space. These thermal partition functions can in turn be expressed as path integrals on branched coverings of the (d+1)-dimensional sphere and S^1 x H^d, respectively. We calculate the Renyi entropies of free massless scalars and fermions in d=2, and show how using zeta-function regularization one finds agreement between the calculations on the branched coverings of S^3 and on S^1 x H^2. Analogous calculations for massive free fields provide monotonic interpolating functions between the Renyi entropies at the Gaussian and the trivial fixed points. Finally, we discuss similar Renyi entropy calculations in d>2.
description: 35 pages, 4 figures; v2 refs added, minor changes
Coloring, List Coloring, and Painting Squares of Graphs (and other related problems)
Creators: name: Cranston, Daniel W.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05C15, 05C10, 05C76

description: We survey work on coloring, list coloring, and painting squares of graphs; in particular, we consider strong edge-coloring. We focus primarily on planar graphs and other sparse classes of graphs.
description: 32 pages, 13 figures and tables, plus 195-entry bibliography, comments are welcome, published as a Dynamic Survey in Electronic Journal of Combinatorics
Additional file 2: of Neurofilament levels, disease activity and brain volume during follow-up in multiple sclerosis
Creators: name: HĂĽkansson, Irene
name: Tisell, Anders
name: Cassel, Petra
name: Blennow, Kaj
name: Zetterberg, Henrik
name: Lundberg, Peter
name: Dahle, Charlotte
name: Vrethem, Magnus
name: Ernerudh, Jan
Publisher: name: figshare
Year: 2018
Subjects: subject: Biochemistry
subject: Medicine
subject: Cell Biology
subject: Neuroscience
subject: Sociology
subject: FOS: Sociology
subject: Immunology
subject: FOS: Clinical medicine
subject: Biological Sciences not elsewhere classified
subject: Developmental Biology
subject: Computational Biology

description: Table S2. Neuroinflammatory and neurodegenerative markers with respect to separation of patients with and without disease activity during follow-up. (DOCX 17 kb)
Critical fields and growth rates of the Tayler instability as probed by a columnar gallium experiment
Creators: name: Ruediger, Guenther
name: Gellert, Marcus
name: Schultz, Manfred
name: Strassmeier, Klaus G.
name: Stefani, Frank
name: Gundrum, Thomas
name: Seilmayer, Martin
name: Gerbeth, Gunter
Publisher: name: arXiv
Year: 2012
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Many astrophysical phenomena (such as the slow rotation of neutron stars or the rigid rotation of the solar core) can be explained by the action of the Tayler instability of toroidal magnetic fields in the radiative zones of stars. In order to place the theory of this instability on a safe fundament it has been realized in a laboratory experiment measuring the critical field strength, the growth rates as well as the shape of the supercritical modes. A strong electrical current flows through a liquid-metal confined in a resting columnar container with an insulating outer cylinder. As the very small magnetic Prandtl number of the gallium-indium-tin alloy does not influence the critical Hartmann number of the field amplitudes, the electric currents for marginal instability can also be computed with direct numerical simulations. The results of this theoretical concept are confirmed by the experiment. Also the predicted growth rates of the order of minutes for the nonaxisymmetric perturbations are certified by the measurements. That they do not directly depend on the size of the experiment is shown as a consequence of the weakness of the applied fields and the absence of rotation.
description: 8 pages, 5 figures, accepted by ApJ
Do Mechanical and Structural Characteristics of Degenerated Intervertebral Discs Contribute to Development of Degenerative Scoliosis and Spondylolisthesis?
Creators: name: Bader, Taylor J.
Publisher: name: Graduate Studies
Year: 2023
Subjects: subject: Intervertebral disc
subject: Annulus fibrosus
subject: Scoliosis
subject: Spondylolisthesis
subject: Shear
subject: Histology
subject: Optical coherence tomography
subject: Medicine and Surgery
subject: Engineering--Biomedical

description: Intervertebral disc (IVD) degeneration is the age-related breakdown of the cushioned discs that serve as the principal connection between the vertebral bodies. Although affecting 80% of individuals over the age of 50, the causes of the highly varied severity of this disease are not well understood. Additionally, in some cases, primarily in women, the degeneration of the IVD leads to spinal deformities. Degenerative scoliosis (dScoli), the lateral translation and rotation of the vertebrae, and degenerative spondylolisthesis (dSpondy), the forward slippage of the vertebrae with respect to its caudal neighbour, both potentially lead to immobility and pain. These conditions involve increased instability of motion segments of the spine, cascading into further degeneration. The aim of this study was to compare the shear mechanical behaviour of the annulus fibrosus (AF), the outer portion of the IVD, in normal, non-deformity degenerated (degen), dScoli, and dSpondy patients. Small sections of the AF were collected from healthy donors and surgical patients and sheared, mimicking the translation seen in spinal deformity. These same AF sections were scored for degeneration through histology and their lamellar structure was measured with optical coherence tomography (OCT). From these tests, the structure-function relationship of degenerated AF was analyzed to explore degenerative changes. A reduced shear stiffness in degen samples (radial 27 ± 24 kPa, circumferential 57 ± 43 kPa) when compared to normal tissue (radial 80 ± 38 kPa, circumferential 231 ± 73 kPa) was found (p < 0.05). dScoli tissue were further reduced in shear stiffness (radial 12 ± 6 kPa, circumferential 33 ± 21 kPa), although not significantly. There were significant trends linking an increase in structure degeneration, by histology (rS = -0.58, p < 0.01) and OCT (rS = -0.70, p < 0.01), to decreased circumferential shear modulus. Differences in structure and shear stiffness will serve as the backbone for further research into surgical tissue to better understand the progression of IVD degeneration and spinal deformities. Through understanding of the structure-function relationship of the AF, predictors of outcomes and potential treatments could help patients better manage these painful conditions.
Reimagining the stages of exile : Carmen Aguirre's The Refugee Hotel
Creators: name: Herrera-Lasso Gonzalez, Martha
Publisher: name: University of British Columbia
Year: 2012

description: The purpose of this study is to examine the process of translating a personal experience of refuge into a theatre form in the country of exile. The study focuses on The Refugee Hotel by Chilean-Canadian playwright Carmen Aguirre, a biographical drama about her exile to Canada at the age of six after the coup d’état in Chile in 1973. Aguirre is a prime example of a refugee artist who has transposed her personal experience of exile into her drama, referencing not only her own story and the history of Chile, but also contributing to the history of her country of exile. In the first chapter I attempt to understand the exilic experience in relation to art, with the objective of placing Carmen Aguirre’s biography and work within the confines of previous literature on exile artistry and introducing her perspectives on themes of home and exile. In the second chapter I observe the challenges of dramatizing a refugee testimony, and identify the ways in which theatre as an artistic medium can provide unique ways of healing and sharing the experience of exile. The final chapter is focused on the analysis of The Refugee Hotel and the specific ways in which Aguirre experiments with theatrical elements in this play in order to offer a diverse representation of the exilic experience to a diverse Canadian audience. With this analysis of Aguirre’s oeuvre I aim to reflect on the profound complexity of diaspora and how theatre as an artistic medium can offer a stage on which to share and heal the internal, geographical and cultural fragmentations born from displacement.
Evaluation of the Associations between Prenatal Cannabis Use and Infant Developmental Outcomes at 12 Months of Age
Creators: name: Watts, Dana
Publisher: name: Graduate Studies
Year: 2023
Subjects: subject: Prenatal substance use
subject: Infant development
subject: Psychology--Experimental

description: Despite warnings from governing health bodies advising against using cannabis products during preconception, pregnancy, and breastfeeding, cannabis continues to be commonly consumed by pregnant individuals. Past research has found associations between children exposed to cannabis prenatally and adverse childhood development outcomes; however, some of these studies fail to control for important confounding variables, and many are becoming outdated. Using data from the Pregnancy During the Pandemic cohort, the current project evaluated prenatal cannabis use and its association with increased risk of developmental delay across five domains: communication, gross motor, fine motor, problem-solving, and personal social skills. In addition, the association between prenatal cannabis use, birth weight, and instances of preterm birth is explored, and sociodemographic differences between cannabis users and non-users are described. Using multiple linear regression analysis, no significant associations were found between prenatal cannabis use and greater risk of infant development delay in any domain (ps > .05). Prenatal cannabis use was not associated with greater instances of preterm birth or lower birth weight. Cannabis users and non-users significantly differed on all measured sociodemographic variables.
From the Hardness of Detecting Superpositions to Cryptography: Quantum Public Key Encryption and Commitments
Creators: name: Hhan, Minki
name: Morimae, Tomoyuki
name: Yamakawa, Takashi
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: Cryptography and Security (cs.CR)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Recently, Aaronson et al. (arXiv:2009.07450) showed that detecting interference between two orthogonal states is as hard as swapping these states. While their original motivation was from quantum gravity, we show its applications in quantum cryptography. 1. We construct the first public key encryption scheme from cryptographic \emph{non-abelian} group actions. Interestingly, the ciphertexts of our scheme are quantum even if messages are classical. This resolves an open question posed by Ji et al. (TCC '19). We construct the scheme through a new abstraction called swap-trapdoor function pairs, which may be of independent interest. 2. We give a simple and efficient compiler that converts the flavor of quantum bit commitments. More precisely, for any prefix X,Y $\in$ {computationally,statistically,perfectly}, if the base scheme is X-hiding and Y-binding, then the resulting scheme is Y-hiding and X-binding. Our compiler calls the base scheme only once. Previously, all known compilers call the base schemes polynomially many times (Crépeau et al., Eurocrypt '01 and Yan, Asiacrypt '22). For the security proof of the conversion, we generalize the result of Aaronson et al. by considering quantum auxiliary inputs.
description: 51 pages
The smallest bimolecular mass-action system with a vertical Andronov-Hopf bifurcation
Creators: name: Banaji, Murad
name: Boros, Balázs
name: Hofbauer, Josef
Publisher: name: arXiv
Year: 2022
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: We present a three-dimensional differential equation, which robustly displays a degenerate Andronov-Hopf bifurcation of infinite codimension, leading to a center, i.e., an invariant two-dimensional surface that is filled with periodic orbits surrounding an equilibrium. The system arises from a three-species bimolecular chemical reaction network consisting of four reactions. In fact, it is the only such mass-action system that admits a center via an Andronov-Hopf bifurcation.
An assessment of the vitamin A maize seed delivery efforts to date: Agro-dealer sales and farmer production in Zambia
Creators: name: Diressie, Michael Tedla
name: Zulu, Esther
name: Smale, Melinda
name: Eliab Simpungwe
name: Birol, Ekin
Publisher: name: Gates Open Research
Year: 2019

description: An assessment of the vitamin A maize seed delivery efforts to date: Agro-dealer sales and farmer production in Zambia
Fermi~I particle acceleration in converging flows mediated by magnetic reconnection
Creators: name: Bosch-Ramon, V.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Context. Converging flows with strong magnetic fields of different polarity can accelerate particles through magnetic reconnection. If the particle mean free path is longer than the reconnection layer is thick, but much shorter than the entire reconnection structure, the particle will mostly interact with the incoming flows potentially with a very low escape probability. Aims. We explore, in general and also in some specific scenarios, the possibility of particles to be accelerated in a magnetic reconnection layer by interacting only with the incoming flows. Methods. We characterize converging flows that undergo magnetic reconnection, and derive analytical estimates for the particle energy distribution, acceleration rate, and maximum energies achievable in these flows. We also discuss a scenario, based on jets dominated by magnetic fields of changing polarity, in which this mechanism may operate. Results. The proposed acceleration mechanism operates if the reconnection layer is much thinner than its transversal characteristic size, and the magnetic field has a disordered component. Synchrotron losses may prevent electrons from entering in this acceleration regime. The acceleration rate should be faster, and the energy distribution of particles harder than in standard diffusive shock acceleration. The interaction of obstacles with the innermost region of jets in active galactic nuclei and microquasars may be suitable sites for particle acceleration in converging flows.
description: 4 pages, 2 figures, Reserch Note, in press, A&A (final version)
title: Mourning as Resistance: Seeing and Hearing the Borderlands through Vistas de la Frontera
Creators: name: Quintanilla, Alyssa
Publisher: name: The Digital Review
Year: 2021

description: Vistas de la Frontera is a digital memorial for migrants who have died crossing the United States-Mexico borderlands. In order to make their deaths more visible, the piece uses 360 techonologies to make the spaces interactive for users in distant places. This memorial is part of a continuation of work on memorials in the borderlands the continuous violence unfolding there as part of American national security.
Higher-order anisotropic flows and dihadron correlations in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV in a multiphase transport model
Creators: name: Xu, Jun
name: Ko, Che Ming
Publisher: name: arXiv
Year: 2011
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Using a multiphase transport model that includes both initial partonic and final hadronic scatterings, we have studied higher-order anisotropic flows as well as dihadron correlations as functions of pseudorapidity and azimuthal angular differences between trigger and associated particles in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. With parameters in the model determined previously from fitting the measured multiplicity density of mid-pseudorapidity charged particles in central collisions and their elliptic flow in mid-central collisions, the calculated higher-order anisotropic flows from the two-particle cumulant method reproduce approximately those measured by the ALICE Collaboration, except at small centralities where they are slightly overestimated. Similar to experimental results, the two-dimensional dihadron correlations at most central collisions show a ridge structure at the near side and a broad structure at the away side. The short- and long-range dihadron azimuthal correlations, corresponding to small and large pseudorapidity differences, respectively, are studied for triggering particles with different transverse momenta and are found to be qualitatively consistent with experimental results from the CMS Collaboration. The relation between the short-range and long-range dihadron correlations with that induced by back-to-back jet pairs produced from initial hard collisions is also discussed.
description: 7 pages, 7 figures, version to appear in Phys. Rev. C
Contextuality in distributed systems
Creators: name: Evangelou-Oost, Nasos
name: Bannister, Callum
name: Hayes, Ian J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Logic in Computer Science (cs.LO)
subject: FOS: Computer and information sciences

description: We present a lattice of distributed program specifications, whose ordering represents implementability/refinement. Specifications are modelled by families of subsets of relative execution traces, which encode the local orderings of state transitions, rather than their absolute timing according to a global clock. This is to overcome fundamental physical difficulties with synchronisation. The lattice of specifications is assembled and analysed with several established mathematical tools. Sets of nondegenerate cells of a simplicial set are used to model relative traces, presheaves model the parametrisation of these traces by a topological space of variables, and information algebras reveal novel constraints on program correctness. The latter aspect brings the enterprise of program specification under the widening umbrella of contextual semantics introduced by Abramsky et al. In this model of program specifications, contextuality manifests as a failure of a consistency criterion comparable to Lamport's definition of sequential consistency. The theory of information algebras also suggests efficient local computation algorithms for the verification of this criterion. The novel constructions in this paper have been verified in the proof assistant Isabelle/HOL.
description: 22 pages