cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Electronic Spectra of Ytterbium Fluoride from Relativistic Electronic Structure Calculations
Creators: name: Pototschnig, Johann V.
name: Dyall, Kenneth G.
name: Visscher, Lucas
name: Gomes, André S. P.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: We report an investigation of the low-lying excited states of the YbF molecule--a candidate molecule for experimental measurements of the electron electric dipole moment--with 2-component based multi-reference configuration interaction (MRCI), equation of motion coupled cluster (EOM-CCSD) and the extrapolated intermediate Hamiltonian Fock-space coupled cluster (XIHFS-CCSD). Specifically, we address the question of the nature of these low-lying states in terms of configurations containing filled or partially-filled Yb $4f$ shells. We show that while it does not appear possible to carry out calculations with both kinds of configurations contained in the same active space, reliable information can be extracted from different sectors of Fock space--that is, by performing electron attachment and detachment IHFS-CCSD and EOM-CCSD calculation on the closed-shell YbF$^+$ and YbF$^-$ species, respectively. From these we observe $Ω= 1/2, 3/2$ states that arise from the $4f^{13}σ_{6s}^2$, $4f^{14}5d$/$6p$, and $4f^{13}5dσ_{6s}$ configurations appear in the same energy range around the ground-state equilibrium geometry and they are therefore able to interact. As these states are generated from different sectors of Fock space, they are almost orthogonal and provide complementary descriptions of parts of the excited state manifold. To obtain a comprehensive picture, we introduce a simple adiabatization model to extract energies of interacting $Ω= 1/2, 3/2$ states that can be compared to experimental observations.
description: 28+57 pages, 8+18 tables, 5+34 figures
Topological insulators from the perspective of non-commutative geometry and index theory
Creators: name: Schulz-Baldes, Hermann
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Topological insulators are solid state systems of independent electrons for which the Fermi level lies in a mobility gap, but the Fermi projection is nevertheless topologically non-trivial, namely it cannot be deformed into that of a normal insulator. This non-trivial topology is encoded in adequately defined invariants and implies the existence of surface states that are not susceptible to Anderson localization. This non-technical review reports on recent progress in the understanding of the underlying mathematical structures, with a particular focus on index theory.
description: to appear in Jahresberichte DMV
A polytopal method for the Brinkman problem robust in all regimes
Creators: name: Di Pietro, Daniele A.
name: Droniou, Jérôme
Publisher: name: arXiv
Year: 2023
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 65N30, 65N08, 76S05, 76D07

description: In this work we develop a discretisation method for the Brinkman problem that is uniformly well-behaved in all regimes (as identified by a local dimensionless number with the meaning of a friction coefficient) and supports general meshes as well as arbitrary approximation orders. The method is obtained combining ideas from the Hybrid High-Order and Discrete de Rham methods, and its robustness rests on a potential reconstruction and stabilisation terms that change in nature according to the value of the local friction coefficient. We derive error estimates that, thanks to the presence of cut-off factors, are valid across the all regimes and provide extensive numerical validation.
Exposing minimal composition of Kohn-Sham theory and its extendability
Creators: name: Nakada, H.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Reducing the many-fermion problem to a set of single-particle (s.p.) equations, the Kohn-Sham (KS) theory has provided a practical tool to implement \textit{ab initio} calculations of ground-state energies and densities in many-electron systems. There have been attempts to extend the KS theory so that it could describe other physical quantities, or it could be applied to other many-fermion systems. By generalizing and reformulating the KS theory in terms of the 1-body density matrix, we expose the minimal composition of the theory that enables the reduction of the many-fermion problem to the s.p. equations. Based on the reformulation, several basic issues are reconsidered. The $v$- and $N$-representabilities for the KS theory are distinguished from those for the Hohenberg-Kohn theorem. Criteria for the extendability of the KS theory are addressed.
description: 33 pages including 2 figures; to appear in Phys. Scr. (Several typos have been corrected from the previous version.)
The streamlines of $\infty$-harmonic functions obey the inverse mean curvature flow
Creators: name: Moser, Roger
Publisher: name: arXiv
Year: 2021
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: Given an $\infty$-harmonic function $u_\infty$ on a domain $Ω\subseteq \mathbb{R}^2$, consider the function $w = -\log |\nabla u_\infty|$. If $u_\infty \in C^2(Ω)$ with $\nabla u_\infty \neq 0$ and $\nabla |\nabla u_\infty| \neq 0$, then it is easy to check that (1) the streamlines of $u_\infty$ are the level sets of $w$ and (2) $w$ solves the level set formulation of the inverse mean curvature flow. For less regular solutions, neither statement is true in general, but even so, $w$ is still a weak solution of the inverse mean curvature flow under far weaker assumptions. This is proved through an approximation of $u_\infty$ by $p$-harmonic functions, the use of conjugate $p'$-harmonic functions, and the known connection of the latter with the inverse mean curvature flow. A statement about the regularity of $|\nabla u_\infty|$ arises as a by-product.
Weak universality in sensory tradeoffs
Creators: name: Marzen, Sarah
name: DeDeo, Simon
Publisher: name: arXiv
Year: 2016
Subjects: subject: Neurons and Cognition (q-bio.NC)
subject: FOS: Biological sciences

description: For many organisms, the number of sensory neurons is largely determined during development, before strong environmental cues are present. This is despite the fact that environments can fluctuate drastically both from generation to generation and within an organism's lifetime. How can organisms get by by hard-coding the number of sensory neurons? We approach this question using rate-distortion theory. A combination of simulation and theory suggests that when environments are large, the rate-distortion function---a proxy for material costs, timing delays, and energy requirements---depends only on coarse-grained environmental statistics that are expected to change on evolutionary, rather than ontogenetic, timescales.
Local convergence and stability of tight bridge-addable graph classes
Creators: name: Chapuy, Guillaume
name: Perarnau, Guillem
Publisher: name: arXiv
Year: 2016
Subjects: subject: Combinatorics (math.CO)
subject: Probability (math.PR)
subject: FOS: Mathematics

description: A class of graphs is bridge-addable if given a graph $G$ in the class, any graph obtained by adding an edge between two connected components of $G$ is also in the class. The authors recently proved a conjecture of McDiarmid, Steger, and Welsh stating that if $\mathcal{G}$ is bridge-addable and $G_n$ is a uniform $n$-vertex graph from $\mathcal{G}$, then $G_n$ is connected with probability at least $(1+o_n(1))e^{-1/2}$. The constant $e^{-1/2}$ is best possible since it is reached for the class of all forests. In this paper we prove a form of uniqueness in this statement: if $\mathcal{G}$ is a bridge-addable class and the random graph $G_n$ is connected with probability close to $e^{-1/2}$, then $G_n$ is asymptotically close to a uniform $n$-vertex random forest in some local sense. For example, if the probability converges to $e^{-1/2}$, then $G_n$ converges in the sense of Benjamini-Schramm to the uniform infinite random forest $F_\infty$. This result is reminiscent of so-called "stability results" in extremal graph theory, with the difference that here the stable extremum is not a graph but a graph class.
description: 45 pages
Matrix Concentration Inequalities and Free Probability
Creators: name: Bandeira, Afonso S.
name: Boedihardjo, March T.
name: van Handel, Ramon
Publisher: name: arXiv
Year: 2021
Subjects: subject: Probability (math.PR)
subject: Functional Analysis (math.FA)
subject: Operator Algebras (math.OA)
subject: FOS: Mathematics
subject: 60B20, 60E15, 46L53, 46L54, 15B52

description: A central tool in the study of nonhomogeneous random matrices, the noncommutative Khintchine inequality, yields a nonasymptotic bound on the spectral norm of general Gaussian random matrices $X=\sum_i g_i A_i$ where $g_i$ are independent standard Gaussian variables and $A_i$ are matrix coefficients. This bound exhibits a logarithmic dependence on dimension that is sharp when the matrices $A_i$ commute, but often proves to be suboptimal in the presence of noncommutativity. In this paper, we develop nonasymptotic bounds on the spectrum of arbitrary Gaussian random matrices that can capture noncommutativity. These bounds quantify the degree to which the spectrum of $X$ is captured by that of a noncommutative model $X_{\rm free}$ that arises from free probability theory. This "intrinsic freeness" phenomenon provides a powerful tool for the study of various questions that are outside the reach of classical methods of random matrix theory. Our nonasymptotic bounds are easily applicable in concrete situations, and yield sharp results in examples where the noncommutative Khintchine inequality is suboptimal. When combined with a linearization argument, our bounds imply strong asymptotic freeness for a remarkably general class of Gaussian random matrix models that may be very sparse, have dependent entries, and lack any special symmetries. When combined with a universality principle, our bounds extend beyond the Gaussian setting to general sums of independent random matrices.
description: 56 pages
MUSE crowded field 3D spectroscopy in NGC 300 : IV. Planetary nebula luminosity function
Creators: name: Soemitro, Azlizan A.
name: Roth, Martin M.
name: Weilbacher, Peter M.
name: Ciardullo, Robin
name: Jacoby, George H.
name: Monreal-Ibero, Ana
name: Castro, Norberto
name: Micheva, Genoveva
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We perform a deep survey of planetary nebulae (PNe) in the spiral galaxy NGC 300 to construct its planetary nebula luminosity function (PNLF). We aim to derive the distance using the PNLF and to probe the characteristics of the most luminous PNe. We analyse 44 fields observed with MUSE at the VLT, covering a total area of $\sim11$ kpc$^2$. We find [OIII]5007 sources using the differential emission line filter (DELF) technique. We identify PNe through spectral classification using the aid of the BPT-diagram. The PNLF distance is derived using the maximum likelihood estimation technique. For the more luminous PNe, we also measure their extinction using the Balmer decrement. We estimate the luminosity and effective temperature of the central stars of the luminous PNe, based on estimates of the excitation class and the assumption of optically thick nebulae. We identify 107 PNe and derive a most-likely distance modulus $(m-M)_0 = 26.48^{+0.11}_{-0.26}$ ($d = 1.98^{+0.10}_{-0.23}$ Mpc). We find that the PNe at the PNLF cut-off exhibit relatively low extinction, with some high extinction cases caused by local dust lanes. We present the lower limit luminosities and effective temperatures of the central stars for some of the brighter PNe. We also identify a few Type I PNe that come from a young population with progenitor masses $>2.5 \, M_\odot$, however do not populate the PNLF cut-off. The spatial resolution and spectral information of MUSE allow precise PN classification and photometry. These capabilities also enable us to resolve possible contamination by diffuse gas and dust, improving the accuracy of the PNLF distance to NGC 300.
description: 20 pages, 11 figures. Accepted for publication in A&A
An industry analysis of the Singapore non-life reinsurance industry
Creators: name: Tan, Samuel C. K. .
Publisher: name: Monash University
Year: 2022

description: This thesis was scanned from the print manuscript for digital preservation and is copyright the author.
 Researchers can access this thesis by asking their local university, institution or public library to
 make a request on their behalf. Monash staff and postgraduate students can use the link in the References field.
Summary of Groundwater Conditions in the Sturgeon River Basin
Creators: Oiffer, Alex
Publisher: name: University of Alberta Library
Year: 2019

The Sturgeon River is a small, precipitation and groundwater fed prairie river. This document provides an overview of the hydrogeological conditions in the Sturgeon River Basin based on existing information. It forms a generalized framework for the role of groundwater in sustaining the Sturgeon River and (select) lakes in the basin. Key data gaps in the understanding of the potential interactions of groundwater with the Sturgeon River and lakes are identified and recommendations are suggested for addressing the data gaps. (As cited on https://www.nswa.ab.ca/)
Incremental Nonlinear Dynamic Inversion based Optical Flow Control for Flying Robots: An Efficient Data-driven Approach
Creators: name: Ho, Hann Woei
name: Zhou, Ye
Publisher: name: arXiv
Year: 2023
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: This paper presents a novel approach for optical flow control of Micro Air Vehicles (MAVs). The task is challenging due to the nonlinearity of optical flow observables. Our proposed Incremental Nonlinear Dynamic Inversion (INDI) control scheme incorporates an efficient data-driven method to address the nonlinearity. It directly estimates the inverse of the time-varying control effectiveness in real-time, eliminating the need for the constant assumption and avoiding high computation in traditional INDI. This approach effectively handles fast-changing system dynamics commonly encountered in optical flow control, particularly height-dependent changes. We demonstrate the robustness and efficiency of the proposed control scheme in numerical simulations and also real-world flight tests: multiple landings of an MAV on a static and flat surface with various tracking setpoints, hovering and landings on moving and undulating surfaces. Despite being challenged with the presence of noisy optical flow estimates and the lateral and vertical movement of the landing surfaces, the MAV is able to successfully track or land on the surface with an exponential decay of both height and vertical velocity at almost the same time, as desired.
Solar Energetic Particle Events with Protons above 500 MeV between 1995 and 2015 Measured with SOHO/EPHIN
Creators: name: Kühl, Patrick
name: Dresing, Nina
name: Heber, Bernd
name: Klassen, Andreas
Publisher: name: arXiv
Year: 2016
Subjects: subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: The Sun is an effective particle accelerator producing solar energetic particle (SEP) events during which particles up to several GeVs can be observed. Those events observed at Earth with the neutron monitor network are called ground level enhancements (GLEs). Although these events with a high energy component have been investigated for several decades, a clear relation between the spectral shape of the SEPs outside the Earth's magnetosphere and the increase in neutron monitor count rate has yet to be established. Hence, an analysis of these events is of interest for the space weather as well as the solar event community. In this work, SEP events with protons accelerated to above 500 MeV have been identified using data from the Electron Proton Helium Instrument (EPHIN) aboard the Solar and Heliospheric Observatory (SOHO) between 1995 and 2015. For a statistical analysis, onset times have been determined for the events and the proton energy spectra were derived and fitted with a power law. As a result, a list of 42 SEP events with protons accelerated to above 500 MeV measured with the EPHIN instrument onboard SOHO is presented. The statistical analysis based on the fitted spectral slopes and absolute intensities is discussed with special emphasis on whether or not an event has been observed as GLE. Furthermore, a correlation between the derived intensity at 500 MeV and the observed increase in neutron monitor count rate has been found for a subset of events.
Coffee stain effect on a fibre from axisymmetric droplets
Creators: name: Corpart, Marie
name: Restagno, Frédéric
name: Boulogne, François
Publisher: name: arXiv
Year: 2023
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: The so-called coffee stain effect has been intensively studied over the past decades, but most of the studies are focused on sessile droplets. In this paper, we analyse the origin of the difference between the deposition of suspended particles in a sessile drop and in an axisymmetric drop deposited on a fibre. First, we model the shape of a drop on a fibre and its evaporative flux with some approximations to derive analytical calculations. Then, for pinned contact lines, we solve the hydrodynamics equations in the liquid phase under the lubrication approximation to determine the flow velocity toward the contact lines. We comment these results by comparison to a sessile drop of similar evaporating conditions, and we show that the substrate curvature plays a role on the contact line depinning, the local evaporative flux, and the liquid flow field. The competition between the advection and the Brownian motion indicates that the transport of the particles toward the contact line occurs in a volume localised in the close vicinity of the contact lines for a drop on a fibre. Thus, the fibre geometry induces a weaker accumulation of particles at the contact line compared to a sessile drop, leading to the more homogeneous deposit observed experimentally.
Probing the longitudinal spin transfer via dihadron polarization correlations in unpolarized $e^+e^-$ and $pp$ collisions
Creators: name: Zhang, Hao-Cheng
name: Wei, Shu-Yi
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The longitudinal spin transfer represents the probability density of producing longitudinally polarized hadrons from longitudinally polarized quarks or circularly polarized gluons. It thus was usually measured in polarized reactions or high-energy collisions where weak interaction dominates. In this work, we propose the dihadron polarization correlation as a novel probe of this quantity. Such an observable does not require the fragmenting partons to be polarized and therefore can be measured in the currently available experimental facilities, such as Belle, RHIC, Tevatron, and the LHC. We make quantitative predictions for these experiments. In light of the data already harvested, the experimental investigation of this observable provides more opportunity for the quantitative study of the longitudinal spin transfer. In particular, the measurements in pp collisions can significantly constrain the fragmentation function of a circularly polarized gluon.
description: Slightly revised. To be published in Physics Letters B
title: The Little Become Big?: Ambit and London's Little Magazines, 1959-1999
Creators: name: Vowles, Christopher George
Publisher: name: Goldsmiths, University of London
Year: 2006

description: In The Little Magazines: A Study of Six Editors (1976), Ian Hamilton described the little magazine as a medium 'which exists, indeed thrives, outside the usual business structure of magazine production and distribution; it is independent, amateur and idealistic' (pp. 7-8). Although this definition applies to many titles of the Thirties, Forties and Fifties, it fails to register radical improvements in magazine design, distribution and book-keeping prompted by the mimeo revolution in the Sixties, Arts Council (ACGB) rationalisation in the Seventies and Eighties, and electronic publishing in the Nineties. This thesis offers a literary-historical account of Ambit's evolution from a scruffy, mimeo-produced pamphlet to a glossy, ACGB-sponsored quarterly. It provides a decade-by-decade analysis of Ambit's principal formal and thematic concerns, relating them to the work of key contributors in poetry, prose fiction and the visual arts, and detailing the emergence of a distinctive Ambit identity. At the same time, Ambit is also treated as a chronologue of the formal development of the contemporary little magazine, registering the complex economic, cultural and technological stimuli that affected the medium between 1959 and 1999. Both approaches are designed to test Hamilton's reading of little magazine history against a. detailed study of a major literary-arts quarterly of the post-1960 period, and identify ways in which contemporary publications like Ambit (1959- ), Agenda (1959- ), New Departures (1959- ) and Stand (1952- ) have departed from Hamilton's highly romanticised conception of 'littleness'. The thesis concludes by suggesting that Ambit and its contemporaries have sacrificed independence, amateurism and idealism for the entrepreneurial pragmatism that has sustained their commitment to the 'non-commercial' publication of 'artistic work from unknown or relatively unknown writers' that Frederick J. Hoffman et al in The Little Magazine: A History and a Bibliography (1946) (p. 2) saw as the little magazine's raison d'être.
ALMA Measurement of 10 kpc-scale Lensing Power Spectra towards the Lensed Quasar MG J0414+0534
Creators: name: Inoue, Kaiki Taro
name: Minezaki, Takeo
name: Matsushita, Satoki
name: Nakanishi, Koichiro
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The lensing power spectra for gravitational potential, astrometric shift, and convergence perturbations are powerful probes to investigate dark matter structures on small scales. We report the first lower and upper bounds of these lensing power spectra on angular scale $\sim 1$arcsec towards the anomalous quadruply lensed quasar MG$\,$J0414+0534 at a redshift $z=2.639$. To obtain the spectra, we conducted observations of MG$\,$J0414+0534 using the Atacama Large Millimeter/submillimeter Array (ALMA) with high angular resolution (0.02 arcsec to 0.05 arcsec). We developed a new partially non-parametric method in which Fourier coefficients of potential perturbation are adjusted to minimize the difference between linear combinations of weighted mean de-lensed images. Using positions of radio jet components, extended dust emission on scales $>1\,$kpc, and mid-infrared flux ratios, the range of measured convergence, astrometric shift, and potential powers at an angular scale of $\sim 1.1$arcsec (corresponding to an angular wave number of $l=1.2\times 10^6$ or $\sim 9\,$kpc in the primary lens plane) within $1\,σ$ are $\varDelta_κ=0.021-0.028$, $\varDelta_α=7-9\,$mas, and $\varDelta_ψ=1.2-1.6\,$$\textrm{mas}^2$, respectively. Our result is consistent with the predicted abundance of halos in the line of sight and subhalos in cold dark matter models. Our partially non-parametric lens models suggest a presence of a clump in the vicinity of object Y, a possible dusty dwarf galaxy and some small clumps in the vicinity of other lensed quadruple images. Although much fainter than the previous report, we detected weak continuum emission possibly from object Y with a peak flux of $\sim 100\,μ\textrm{Jy}\, \textrm{beam} ^{-1}$ at the $\sim 4\,σ$ level.
description: 54 pages, 35 figures, version accepted in ApJ. Analyses of models with a possible dwarf galaxy, object Y and that of chi^2 fit in the visibility plane were added. A new section 7 about CDM consistency was added. The angular scale of the smallest angular bin in Figure 24 was corrected
Dispersion Relation of a Surface Wave at a Rough Metal-Air Interface
Creators: name: Kotelnikov, Igor
name: Stupakov, Gennady
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We derived a dispersion relation of a surface wave at a rough metal-air interface. In contrast to previous publications, we assumed that an intrinsic surface impedance due to a finite electric conductivity of the metal can be of the same order as the roughness-induced impedance. We then applied our results to the analysis of a long-standing problem of the discrepancy between the experimental data on the propagation of surface waves in the terahertz range of frequencies and the classical Drude theory.
description: 9 pages, 2 figures
Vermilion River Watershed Management Plan
Creators: North Saskatchewan Watershed Alliance (NSWA)
Publisher: name: University of Alberta Library
Year: 2012

Purpose of this Plan: This Vermilion River Watershed Management Plan recommends actions that need to be taken to meet the goals of Water for Life: Alberta’s Strategy for Sustainability (2003): safe, secure drinking water; healthy aquatic ecosystems; and reliable quality water supplies for a sustainable economy. (As cited in report.)
Synthesis and processing of lithium-loaded plastic scintillators on the kilogram scale
Creators: name: Ford, Michael J.
name: Aigeldinger, Elisabeth
name: Sutanto, Felicia
name: Zaitseva, Natalia P.
name: Li, Viacheslav A.
name: Carman, M. Leslie
name: Glenn, Andrew
name: Catala, Cristian R.
name: Dazeley, Steven A.
name: Bowden, Nathaniel
Publisher: name: arXiv
Year: 2023
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: Plastic scintillators that can discriminate between gamma rays, fast neutrons, and thermal neutrons were synthesized and characterized while considering the balance between processing and performance at the kilogram scale. These trade-offs were necessitated by the inclusion of 0.1 wt. % lithium-6 to enable detection of thermal neutrons. The synthesis and processing of these plastic scintillators on the kilogram scale required consideration of many factors. First, a comonomer (methacrylic acid) was used to solubilize salts of lithium-6, which allow for a thermal-neutron capture reaction that produces scintillation light following energy transfer. Second, scintillation performance and processability were considered because the increasing content of the comonomer resulted in a sharp decrease in the light output. The use of small amounts of comonomer (less than or equal to 3 wt. %) resulted in better performance but required high processing temperatures. At large scales, these high temperatures could initiate an exothermic polymerization that results in premature curing and/or defects. The deleterious effects of the comonomer may be mitigated by using m-terphenyl as a primary dye rather than 2,5-diphenyloxazole (PPO), which has been traditionally used in organic scintillators. Finally, the curing environment was controlled to avoid defects like cracking and discoloration while maintaining solubility of dopants during curing. For scintillators that were produced from kilogram-scale batches of precursors, the effective attenuation of scintillation light was characterized.
Doppler speeds of the hydrogen Lyman lines in solar flares from EVE
Creators: name: Brown, Stephen A
name: Fletcher, Lyndsay
name: Labrosse, Nicolas
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The hydrogen Lyman lines provide important diagnostic information about the dynamics of the chromosphere, but there have been few systematic studies of their variability during flares. We investigate Doppler shifts in these lines in several flares, and use these to calculate plasma speeds. We use spectral data from the Multiple EUV Grating Spectrograph B (MEGS-B) detector of the Extreme-Ultraviolet Variability Experiment (EVE) instrument on the Solar Dynamics Observatory. MEGS-B obtains full-disk spectra of the Sun at a resolution of 0.1nm in the range 37-105 nm, which we analyse using three independent methods. The first method performs Gaussian fits to the lines, and compares the quiet-Sun centroids with the flaring ones to obtain the Doppler shifts. The second method uses cross-correlation to detect wavelength shifts between the quiet-Sun and flaring line profiles. The final method calculates the "center-of-mass" of the line profile, and compares the quiet-Sun and flaring centroids to obtain the shift. In a study of 6 flares we find strong signatures of both upflow and downflow in the Lyman lines, with speeds measured in Sun-as-a-Star data of around 10 km/s, and speeds in the flare excess signal of around 30 km/s All events showing upflows in Lyman lines are associated with some kind of eruption or coronal flow in imaging data, which may be responsible for the net blueshifts. Events showing downflows in the Lyman lines may be associated with loop contraction or faint downflows, but it is likely that chromospheric condensation flows are also contributing.
Noise-induced absorbing phase transition in a model of opinion formation
Creators: name: Vieira, Allan R.
name: Crokidakis, Nuno
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: In this work we study a 3-state ($+1$, $-1$, $0$) opinion model in the presence of noise and disorder. We consider pairwise competitive interactions, with a fraction $p$ of those interactions being negative (disorder). Moreover, there is a noise $q$ that represents the probability of an individual spontaneously change his opinion to the neutral state. Our aim is to study how the increase/decrease of the fraction of neutral agents affects the critical behavior of the system and the evolution of opinions. We derive analytical expressions for the order parameter of the model, as well as for the stationary fraction of each opinion, and we show that there are distinct phase transitions. One is the usual ferro-paramagnetic transition, that is in the Ising universality class. In addition, there are para-absorbing and ferro-absorbing transitions, presenting the directed percolation universality class. Our results are complemented by numerical simulations.
description: 13 pages, 4 figures, to appear in Phys. Lett. A
Nature of the Antiferromagnetic Order in GdCu$_2$
Creators: name: Kaneko, Koji
name: Tabata, Chihiro
name: Hagihala, Masato
name: Yamauchi, Hiroki
name: Kubota, Masato
name: ToyotakaOsakabe
name: Ōnuki, Yoshichika
Publisher: name: arXiv
Year: 2023
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: A magnetic order in orthorhombic GdCu$_2$ was investigated via a single crystal neutron diffraction with thermal neutron. Magnetic peaks were observed at incommensurate positions described by the ordering vector $q$=($δ$,~1,~0) with $δ$=0.678 at 4.6~K. This ordering vector is close to the commensurate one with $q_{\rm c}$=(2/3,~1,~0) reported earlier, but clearly deviates. The incommensurate nature of the magnetic order in GdCu$_2$ is further corroborated by the peak shift with temperature below $T_{\rm N}$.
description: 6 pages, 3 figures
Short timescale variables in stellar clusters: From Gaia to ground-based telescopes
Creators: name: Roelens, Maroussia
name: Blanco-Cuaresma, Sergi
name: Eyer, Laurent
name: Mowlavi, Nami
name: Lecoeur-Taïbi, Isabelle
name: Rimoldini, Lorenzo
name: Palaversa, Lovro
name: Süveges, Maria
name: Charnas, Jonathan
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Combined studies of variable stars and stellar clusters open great horizons, and they allow us to improve our understanding of stellar cluster formation and stellar evolution. In that prospect, the Gaia mission will provide astrometric, photometric, and spectroscopic data for about one billion stars of the Milky Way. This will represent a major census of stellar clusters, and it will drastically increase the number of known variable stars. In particular, the peculiar Gaia scanning law offers the opportunity to investigate the rather unexplored domain of short timescale variability (from tens of seconds to a dozen of hours), bringing invaluable clues to the fields of stellar physics and stellar aggregates. We assess the Gaia capabilities in terms of short timescale variability detection, using extensive light-curve simulations for various variable object types. We show that Gaia can detect periodic variability phenomena with amplitude variations larger than a few millimagnitudes. Additionally, we plan to perform subsequent follow-up of variables stars detected in clusters by Gaia to better characterize them. Hence, we develop a pipeline for the analysis of high cadence photometry from ground-based telescopes such as the 1.2m Euler telescope (La Silla, Chile) and the 1.2m Mercator telescope (La Palma, Canary Islands).
description: To appear in the 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun proceeding
On the singular two-parameter eigenvalue problem II
Creators: name: Košir, Tomaž
name: Plestenjak, Bor
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: Spectral Theory (math.SP)
subject: FOS: Mathematics
subject: 15A18, 15A21, 15A22, 15A69, 65F15

description: In the 1960s, Atkinson introduced an abstract algebraic setting for multiparameter eigenvalue problems. He showed that a nonsingular multiparameter eigenvalue problem is equivalent to the associated system of generalized eigenvalue problems, which is a key relation for many theoretical results and numerical methods for nonsingular multiparameter eigenvalue problems. In 2009, Muhič and Plestenjak extended the above relation to a class of singular two-parameter eigenvalue problems with coprime characteristic polynomials and such that all finite eigenvalues are algebraically simple. They introduced a way to solve a singular two-parameter eigenvalue problem by computing the common regular eigenvalues of the associated system of two singular generalized eigenvalue problems. Using new tools, in particular the stratification theory, we extend this connection to singular two-parameter eigenvalue problems with possibly multiple eigenvalues and such that characteristic polynomials can have a nontrivial common factor.
description: 18 pages
The MacLane class and the Eremenko-Lyubich class
Creators: name: Barth, Karl F.
name: Rippon, Philip J.
name: Sixsmith, David J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 30D40

description: In 1970 G. R. MacLane asked if it is possible for a locally univalent function in the class $\mathcal{A}$ to have an arc tract. This question remains open, but several results about it have been given. We significantly strengthen these results, in particular replacing the condition of local univalence by the more general condition that the set of critical values is bounded. Also, we adapt a recent powerful technique of C. J. Bishop in order to show that there is a function in the Eremenko-Lyubich class for the disc that is not in the class $\mathcal{A}$.
High-mass eclipsing binaries: a testbed for models of interior structure and evolution -- Accurate fundamental properties and surface chemical composition for V1034 Sco, GL Car, V573 Car and V346 Cen
Creators: name: Pavlovski, K.
name: Southworth, J.
name: Tkachenko, A.
name: Van Reeth, T.
name: Tamajo, E.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The surface chemical compositions of stars are affected by physical processes which bring the products of thermonuclear burning to the surface. Despite their potential in understanding the structure and evolution of stars, elemental abundances are available for only a few high-mass binary stars. We aim to enlarge this sample by determining the physical properties and photospheric abundances for four eclipsing binary systems containing high-mass stars: V1034 Sco, GL Car, V573 Car and V346 Cen. The components have masses 8-17 Msun and effective temperatures from 22500 to 32200 K, and are all on the main sequence. We present new high-resolution and high signal-to-noise spectroscopy from HARPS, and analyse them using spectral disentangling and NLTE spectral synthesis. We model existing light curves and new photometry from the TESS satellite, We measure the stellar masses to 0.6-2.0 percent precision, radii to 0.8-1.7 percent precision, effective temperatures to 1.1-1.6 percent precision, and abundances of C, N, O, Mg and Si. The abundances are similar to those found in our previous studies of high-mass eclipsing binaries; our sample now comprises 25 high-mass stars in 13 binary systems. We also find tidally-excited pulsations in V346 Cen. We reinforce our previous conclusions: interior chemical element transport is not as efficient in binary star components as in their single-star counterparts in the same mass regime and evolutionary stage, possibly due to the effects of tidal forces. Our ultimate goal is to provide a larger sample of OB-type stars in binaries which would enable a thorough comparison to stellar evolutionary models, as well as to single high-mass stars.
description: Accepted for publication in Astronomy & Astrophysics
Reducibility versus definability for pseudovarieties of semigroups
Creators: name: Almeida, J.
name: Klíma, O.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 20M07

description: It is easy to show that a pseudovariety which is reducible with respect to an implicit signature $σ$ for the equation $x=y$ can also be defined by $σ$-identities. We present several negative examples for the converse using signatures in which the pseudovarieties are usually defined. An ordered example issue from the extended Straubing-Thérien hierarchy of regular languages is also shown to provide a positive example for the inequality $x\le y$.
Massive MIMO with Cauchy Noise: Channel Estimation, Achievable Rate and Data Decoding
Creators: name: Gulgun, Ziya
name: Larsson, Erik G.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Information Theory (cs.IT)
subject: Signal Processing (eess.SP)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: We consider massive multiple-input multiple-output (MIMO) systems in the presence of Cauchy noise. First, we focus on the channel estimation problem. In the standard massive MIMO setup, the users transmit orthonormal pilots during the training phase and the received signal at the base station is projected onto each pilot. This processing is optimum when the noise is Gaussian. We show that this processing is not optimal when the noise is Cauchy and as a remedy propose a channel estimation technique that operates on the raw received signal. Second, we derive uplink-downlink achievable rates in the presence of Cauchy noise for perfect and imperfect channel state information. Finally, we derive log-likelihood ratio expressions for soft bit detection for both uplink and downlink, and simulate coded bit-error-rate curves. In addition to this, we derive and compare the symbol detectors in the presence of both Gaussian and Cauchy noises. An important observation is that the detector constructed for Cauchy noise performs well with both Gaussian and Cauchy noises; on the other hand, the detector for Gaussian noise works poorly in the presence of Cauchy noise. That is, the Cauchy detector is robust against heavy-tailed noise, whereas the Gaussian detector is not.
description: To appear in the IEEE Transactions on Wireless Communications, 2023
A multifrequency MUSIC algorithm for locating small inhomogeneities in inverse scattering
Creators: name: Griesmaier, Roland
name: Schmiedecke, Christian
Publisher: name: arXiv
Year: 2016
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 35R30, (65N21)

description: We consider an inverse scattering problem for time-harmonic acoustic or electromagnetic waves. The goal is to localize several small penetrable objects embedded inside an otherwise homogeneous background medium from observations of far field patterns of scattered fields corresponding to plane wave incident fields with one fixed incident direction but several different frequencies. Taking advantage of the smallness of the scatterers with respect to wave length we utilize an asymptotic representation formula for the far field pattern to design and analyze a MUSIC-type reconstruction method for this setup. We establish lower bounds on the number of frequencies and receiver directions required to recover the number and the positions of the scatterers for a given configuration by the reconstruction algorithm. Furthermore we apply the method to the practically interesting case of multifrequency backscattering data. Numerical examples are presented to document the potentials and limitations of this approach.
Long-lived Andreev states as evidence for protected hinge modes in a bismuth nanoring Josephson junction
Creators: name: Bernard, A.
name: Peng, Y.
name: Kasumov, A.
name: Deblock, R.
name: Ferrier, M.
name: Fortuna, F.
name: Volkov, V. T.
name: Kasumov, Yu. A.
name: Oreg, Y.
name: von Oppen, F.
name: Bouchiat, H.
name: Gueron, S.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Second-order topological insulators are characterized by helical, non-spin-degenerate, one-dimensional states running along opposite crystal hinges, with no backscattering. Injecting superconducting pairs therefore entails splitting Cooper pairs into two families of helical Andreev states of opposite helicity, one at each hinge. Here we provide evidence for such separation via the measurement and analysis of switching supercurrent statistics of a crystalline nanoring of bismuth. Using a phenomenological model of two helical Andreev hinge modes, we find that pairs relax at a rate comparable to individual quasiparticles, in contrast with the much faster pair relaxation of non-topological systems. This constitutes a unique tell-tale sign of the spatial separation of topological helical hinges.
description: 10 pages, 5 figures
Electronic control of magnonic and spintronic devices
Creators: name: Tannous, C.
name: Gieraltowski, J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Nanometric magnonic and spintronic devices need magnetic field control in addition to conventional electronic control. In this work we review ways to replace magnetic field control by an electronic one in order to circumvent appearance of stray magnetic fields or the difficulty of creating large magnetic fields over nanometric distances. Voltage control is compared to current control and corresponding devices are compared from their energetic efficiency point of view.
description: 9 pages, 2 figures, 5 tables
Program budgeting in the Victorian public sector : an evaluation
Creators: name: Baines, Annette.
Publisher: name: Monash University
Year: 2022

description: This thesis was scanned from the print manuscript for digital preservation and is copyright the author.
 Researchers can access this thesis by asking their local university, institution or public library to
 make a request on their behalf. Monash staff and postgraduate students can use the link in the References field.
Non-Lorentzian Kač-Moody Algebras
Creators: name: Bagchi, Arjun
name: Chatterjee, Ritankar
name: Kaushik, Rishabh
name: Saha, Amartya
name: Sarkar, Debmalya
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We investigate two dimensional (2d) quantum field theories which exhibit Non- Lorentzian Kač-Moody (NLKM) algebras as their underlying symmetry. Our investigations encompass both 2d Galilean (speed of light $c \rightarrow \infty$) and Carrollian ($c \rightarrow 0$) CFTs with additional number of infinite non-Abelian currents, stemming from an isomorphism between the two algebras. We alternate between an intrinsic and a limiting analysis. Our NLKM algebra is constructed first through a contraction and then derived from an intrinsically Carrollian perspective. We then go on to use the symmetries to derive a Non-Lorentzian (NL) Sugawara construction and ultimately write down the NL equivalent of the Knizhnik Zamolodchikov equations. All of these are also derived from contractions, thus providing a robust cross-check of our analyses.
description: 56 pages
Experimental Adiabatic Quantum Factorization under Ambient Conditions Based on a Solid-State Single Spin System
Creators: name: Xu, Kebiao
name: Xie, Tianyu
name: Li, Zhaokai
name: Xu, Xiangkun
name: Wang, Mengqi
name: Ye, Xiangyu
name: Kong, Fei
name: Geng, Jianpei
name: Duan, Changkui
name: Shi, Fazhan
name: Du, Jiangfeng
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The adiabatic quantum computation is a universal and robust method of quantum computing. In this architecture, the problem can be solved by adiabatically evolving the quantum processor from the ground state of a simple initial Hamiltonian to that of a final one, which encodes the solution of the problem. By far, there is no experimental realization of adiabatic quantum computation on a single solid spin system under ambient conditions, which has been proved to be a compatible candidate for scalable quantum computation. In this letter, we report on the first experimental realization of an adiabatic quantum algorithm on a single solid spin system under ambient conditions. All elements of adiabatic quantum computation, including initial state preparation, adiabatic evolution, and final state readout, are realized experimentally. As an example, we factored 35 into its prime factors 5 and 7 on our adiabatic quantum processor.
Thermoelectric transport and Peltier cooling of cold atomic gases
Creators: name: Grenier, Charles
name: Kollath, Corinna
name: Georges, Antoine
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: This brief review presents the emerging field of mesoscopic physics with cold atoms, with an emphasis on thermal and 'thermoelectric' transport, i.e. coupled transport of particle and entropy. We review in particular the comparison between theoretically predited and experimentally observed thermoelectric effects in such systems. We also show how combining well designed transport properties and evaporative cooling leads to an equivalent of the Peltier effect with cold atoms, which can be used as a new cooling procedure with improved cooling power and efficiency compared to the evaporative cooling currently used in atomic gases. This could lead to a new generation of experiments probing strong correlation effects of ultracold fermionic atoms at low temperatures.
description: 33 pages, 9 figures, Review. To be published in the special issue "Mesoscopic Thermoelectric Phenomena" of C. R. Physique 17 (2016)