cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A New Class of Structured Beamforming for Content-Centric Fog Radio Access Networks
Creators: name: Zhu, W.
name: Tuan, H. D.
name: Dutkiewicz, E.
name: Fang, Y.
name: Hanzo, L.
Publisher: name: arXiv
Year: 2021
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: A multi-user fog radio access network (F-RAN) is designed for supporting content-centric services. The requested contents are partitioned into sub-contents, which are then 'beam- formed' by the remote radio heads (RRHs) for transmission to the users. Since a large number of beamformers must be designed, this poses a computational challenge. We tackle this challenge by proposing a new class of regularized zero forcing beamforming (RZFB) for directly mitigating the inter-content interferences, while the 'intra-content interference' is mitigated by successive interference cancellation at the user end. Thus each beamformer is decided by a single real variable (for proper Gaus- sian signaling) or by a pair of complex variables (for improper Gaussian signaling). Hence the total number of decision variables is substantially reduced to facilitate tractable computation. To address the problem of energy efficiency optimization subject to multiple constraints, such as individual user-rate requirement and the fronthauling constraint of the links between the RRHs and the centralized baseband signal processing unit, as well as the total transmit power budget, we develop low-complexity path- following algorithms. Finally, we actualize their performance by simulations.
Absence of Critical Thickness in an Ultrathin Improper Ferroelectric Film
Creators: name: Sai, Na
name: Fennie, Craig J.
name: Demkov, Alexander A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We study the ferroelectric stability and surface structural properties of an oxygen-terminated hexagonal YMnO$_3$ ultra-thin film using density functional theory. Under an open circuit boundary condition, the ferroelectric state with the spontaneous polarization normal to the (0001) surface, is found to be metastable in a single domain state despite the presence of a depolarizing field. We establish a connection between the result and the role of improper ferroelectric transition. Our results imply that improper ferroelectric ultrathin films can have rather unique properties that are distinctive from those of very thin films of ordinary ferroelectrics.
description: 4 pages, 4 figures
Asymptotically Flat Radiating Solutions in Third Order Lovelock Gravity
Creators: name: Dehghani, M. H.
name: Farhangkhah, N.
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In this paper, we present an exact spherically symmetric solution of third order Lovelock gravity in $n$ dimensions which describes the gravitational collapse of a null dust fluid. This solution is asymptotically (anti-)de Sitter or flat depending on the choice of the cosmological constant. Using the asymptotically flat solution for $n \geq 7$ with a power-law form of the mass as a function of the null coordinate, we present a model for a gravitational collapse in which a null dust fluid radially injects into an initially flat and empty region. It is found that a naked singularity is inevitably formed whose strength is different for the $n = 7$ and $n \geq 8$ cases. In the $n=7$ case, the limiting focusing condition for the strength of curvature singularity is satisfied. But for $n \geq 8$, the strength of curvature singularity depends on the rate of increase of mass of the spacetime. These considerations show that the third order Lovelock term weakens the strength of the curvature singularity.
description: 15 pages, no figure, references added, two appendix added
Directed polymers and the quantum Toda lattice
Creators: name: O'Connell, Neil
Publisher: name: arXiv
Year: 2009
Subjects: subject: Probability (math.PR)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We characterize the law of the partition function of a Brownian directed polymer model in terms of a diffusion process associated with the quantum Toda lattice. The proof is via a multidimensional generalization of a theorem of Matsumoto and Yor concerning exponential functionals of Brownian motion. It is based on a mapping which can be regarded as a geometric variant of the RSK correspondence.
description: Published in at http://dx.doi.org/10.1214/10-AOP632 the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Relic High Frequency Gravitational waves from the Big Bang, and How to Detect Them
Creators: name: Beckwith, A. W.
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: We show conditions for HFGW detection, employing an entropy concept written up by Jack Ng, and Steinhard's proceedure for reconstructing tensorial representations for relic HFGW from the onset of the big bang. The issue of the reality of gravitons as a measurable physical object which was raised by Rothman in 2006 is indirectly answered via a proceedure obtained from Weinberg's 1972 book on gravitation, and all the methodologies so obtained are referenced with respect to engineering specifications of the Li-Baker HFGW detector. In addition, the document also refers to entanglement entropy, and its possible aid in refining measurement predictions. Finally, commentary about HFGW and relic neutrino physics data sets is included, with regards to inflationary model candidates
description: 15 pages, 1 table, 1 figure. Covers two AIP conference proceeding entries. Pages 1-9 correspond to one ias-spes Huntsville, Alabama February 2009 conference paper on the formalism of HFGW analysis, and pages 9-13 correspond to Neutrino physics-HFGW data set comparison, in terms of different inflationary potential candidates
Quantum entanglement in a pure state of strongly correlated quantum impurity systems
Creators: name: Nishikawa, Yunori
name: Yoshioka, Tomoki
Publisher: name: arXiv
Year: 2024
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We consider quantum entanglement in strongly correlated quantum impurity systems for states manifesting interesting properties such as multi-level Kondo effect and dual nature between itineracy and localization etc.. For this purpose, we set up a system consisting of one or two quantum impurities arbitrarily selected from the system as a subsystem, and investigate quantum entanglement with its environmental system. We reduce the pure state of interest as described above to the subsystem, and formulate quantum informative quantities such as entanglement entropy, mutual information and relative entropy. We apply them to quantum impurity systems consisting of several sites and the single impurity Anderson model to study the relationship between their states and the behaviors of quantum informative quantities. The obtained results suggest that the method proposed here is promising for elucidating the quantum entanglement of pure states in various quantum impurity systems.
Arctic circles, domino tilings and square Young tableaux
Creators: name: Romik, Dan
Publisher: name: arXiv
Year: 2009
Subjects: subject: Probability (math.PR)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: The arctic circle theorem of Jockusch, Propp, and Shor asserts that uniformly random domino tilings of an Aztec diamond of high order are frozen with asymptotically high probability outside the "arctic circle" inscribed within the diamond. A similar arctic circle phenomenon has been observed in the limiting behavior of random square Young tableaux. In this paper, we show that random domino tilings of the Aztec diamond are asymptotically related to random square Young tableaux in a more refined sense that looks also at the behavior inside the arctic circle. This is done by giving a new derivation of the limiting shape of the height function of a random domino tiling of the Aztec diamond that uses the large-deviation techniques developed for the square Young tableaux problem in a previous paper by Pittel and the author. The solution of the variational problem that arises for domino tilings is almost identical to the solution for the case of square Young tableaux by Pittel and the author. The analytic techniques used to solve the variational problem provide a systematic, guess-free approach for solving problems of this type which have appeared in a number of related combinatorial probability models.
description: Published in at http://dx.doi.org/10.1214/10-AOP628 the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org)
SPH simulations of grain growth in protoplanetary disks
Creators: name: Laibe, Guillaume
name: Gonzalez, Jean-François
name: Fouchet, Laure
name: Maddison, Sarah T.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Aims: In order to understand the first stages of planet formation, when tiny grains aggregate to form planetesimals, one needs to simultaneously model grain growth, vertical settling and radial migration of dust in protoplanetary disks. In this study, we implement an analytical prescription for grain growth into a 3D two-phase hydrodynamics code to understand its effects on the dust distribution in disks. Methods: Following the analytic derivation of Stepinski & Valageas (1997), which assumes that grains stick perfectly upon collision, we implement a convenient and fast method of following grain growth in our 3D, two-phase (gas+dust) SPH code. We then follow the evolution of the size and spatial distribution of a dust population in a classical T Tauri star disk. Results: We find that the grains go through various stages of growth due to the complex interplay between gas drag, dust dynamics, and growth. Grains initially grow rapidly as they settle to the mid-plane, then experience a fast radial migration with little growth through the bulk of the disk, and finally pile-up in the inner disk where they grow more efficiently. This results in a bimodal distribution of grain sizes. Using this simple prescription of grain growth, we find that grains reach decimetric sizes in 10^5 years in the inner disk and survive the fast migration phase.
description: 6 pages, 6 figures, accepted to A&A. Astronomy and Astrophysics (2008) in press
Additional file 1 of Accelerometer sampling requirements for animal behaviour classification and estimation of energy expenditure
Creators: name: Yu, Hui
name: Muijres, Florian T.
name: te Lindert, Jan Severin
name: Hedenström, Anders
name: Henningsson, Per
Publisher: name: figshare
Year: 2023
Subjects: subject: Space Science
subject: Medicine
subject: Neuroscience
subject: Physiology
subject: FOS: Biological sciences
subject: Ecology
subject: Biological Sciences not elsewhere classified
subject: Cancer

description: Additional file 1. Feature calculations for prey catching and non-prey catching behaviour classification through pied flycatcher accelerometer data.
Local dynamical lattice instabilities: Prerequisites for resonant pairing superconductivity
Creators: name: Ranninger, Julius
name: Romano, Alfonso
Publisher: name: arXiv
Year: 2008
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Fluctuating local diamagnetic pairs of electrons, embedded in a Fermi sea, are candidates for non-phonon-mediated superconductors without the stringent conditions on Tc which arise in phonon-mediated BCS classical low-Tc superconductors. The local accumulations of charge, from which such diamagnetic fluctuations originate, are irrevocably coupled to local dynamical lattice instabilities and form composite charge-lattice excitations of the system. For a superconducting phase to be realized, such excitations must be itinerant spatially phase-coherent modes. This can be achieved by resonant pair tunneling in and out of polaronic cation-ligand sites. Materials in which superconductivity driven by such local lattice instability can be expected, have a Tc which is controlled by the phase stiffness rather than the amplitude of the diamagnetic pair fluctuations. Above Tc, a pseudogap phase will be maintained up to a T*, where this pairing amplitude disappears. We discuss the characteristic local charge and lattice properties which characterize this pseudogap phase and which form the prerequisites for establishing a phase-coherent macroscopic superconducting state.
description: 15 pages, 13 figures
title: Ð­ÐºÑÐ¿ÐµÑÑÐ½ÑÐµ Ð¸ÑÑÐ»ÐµÐ´Ð¾Ð²Ð°Ð½Ð¸Ñ Ð´Ð¾ÑÐ¾Ð¶Ð½Ð¾-ÑÑÐ°Ð½ÑÐ¿Ð¾ÑÑÐ½ÑÑ Ð¿ÑÐ¾Ð¸ÑÑÐµÑÑÐ²Ð¸Ð¹, ÑÐ²ÑÐ·Ð°Ð½Ð½ÑÑ Ñ Ð¿ÑÐ¸ÑÐ¸Ð½ÐµÐ½Ð¸ÐµÐ¼ Ð²ÑÐµÐ´Ð° Ð·Ð´Ð¾ÑÐ¾Ð²ÑÑ
title: Ð²ÑÐ¿ÑÑÐºÐ½Ð°Ñ ÐºÐ²Ð°Ð»Ð¸ÑÐ¸ÐºÐ°ÑÐ¸Ð¾Ð½Ð½Ð°Ñ ÑÐ°Ð±Ð¾ÑÐ° ÑÐ¿ÐµÑÐ¸Ð°Ð»Ð¸ÑÑÐ°
titleType: Subtitle
title: Expert studies of road traffic accidents related to causing harm to health
Creators: name: ÐÐµÐ¼Ð¸Ð½Ð°, ÐÐ»ÐµÐºÑÐ°Ð½Ð´ÑÐ°
Publisher: name: Ð¡Ð°Ð½ÐºÑ-ÐÐµÑÐµÑÐ±ÑÑÐ³ÑÐºÐ¸Ð¹ Ð¿Ð¾Ð»Ð¸ÑÐµÑÐ½Ð¸ÑÐµÑÐºÐ¸Ð¹ ÑÐ½Ð¸Ð²ÐµÑÑÐ¸ÑÐµÑ ÐÐµÑÑÐ° ÐÐµÐ»Ð¸ÐºÐ¾Ð³Ð¾
Year: 2023
Subjects: ÑÑÐ´ÐµÐ±Ð½Ð°Ñ ÑÐºÑÐ¿ÐµÑÑÐ¸Ð·Ð°
Ð´Ð¾ÑÐ¾Ð¶Ð½Ð¾-ÑÑÐ°Ð½ÑÐ¿Ð¾ÑÑÐ½Ð¾Ðµ Ð¿ÑÐ¾Ð¸ÑÑÐµÑÑÐ²Ð¸Ðµ
ÑÐºÑÐ¿ÐµÑÑ-Ð°Ð²ÑÐ¾ÑÐµÑ Ð½Ð¸Ðº
Ð´Ð¾ÑÐ¾Ð¶Ð½Ð¾-ÑÑÐ°Ð½ÑÐ¿Ð¾ÑÑÐ½Ð°Ñ ÑÐ¸ÑÑÐ°ÑÐ¸Ñ
Ð½Ð°ÐµÐ·Ð´ Ð½Ð° Ð¿ÐµÑÐµÑ Ð¾Ð´Ð°
ÑÑÐ¾Ð»ÐºÐ½Ð¾Ð²ÐµÐ½Ð¸Ðµ
forensic examination
auto technical expert
traffic accident
traffic situation
hitting a pedestrian
collision

description: ÐÐ°Ð½Ð½Ð°Ñ ÑÐ°Ð±Ð¾ÑÐ° ÑÐ¾Ð´ÐµÑÐ¶Ð¸Ñ Ð¾Ð¿ÑÐµÐ´ÐµÐ»ÐµÐ½Ð¸Ðµ ÑÑÐ´ÐµÐ±Ð½Ð¾Ð¹ Ð¸Ð½Ð¶ÐµÐ½ÐµÑÐ½Ð¾-ÑÐµÑÐ½Ð¸ÑÐµÑÐºÐ¾Ð¹ ÑÐºÑÐ¿ÐµÑÑÐ¸Ð·Ñ Ð¾Ð±ÑÑÐ¾ÑÑÐµÐ»ÑÑÑÐ² Ð´Ð¾ÑÐ¾Ð¶Ð½Ð¾-ÑÑÐ°Ð½ÑÐ¿Ð¾ÑÑÐ½Ð¾Ð³Ð¾ Ð¿ÑÐ¾Ð¸ÑÑÐµÑÑÐ²Ð¸Ñ, ÑÑÑÐ°Ð½Ð¾Ð²Ð»ÐµÐ½Ñ Ð¿Ð°ÑÐ°Ð¼ÐµÑÑÑ, ÑÐ°ÑÐ°ÐºÑÐµÑÐ¸Ð·ÑÑÑÐ¸Ðµ Ð¼ÐµÑÐ°Ð½Ð¸Ð·Ð¼ Ð²Ð¾Ð·Ð½Ð¸ÐºÐ½Ð¾Ð²ÐµÐ½Ð¸Ñ Ð´Ð¾ÑÐ¾Ð¶Ð½Ð¾-ÑÑÐ°Ð½ÑÐ¿Ð¾ÑÑÐ½Ð¾Ð³Ð¾ Ð¿ÑÐ¾Ð¸ÑÑÐµÑÑÐ²Ð¸Ñ, Ð¾Ð¿ÑÐµÐ´ÐµÐ»ÐµÐ½ Ð¼ÐµÑÐ°Ð½Ð¸Ð·Ð¼ Ð¾Ð±ÑÐ°Ð·Ð¾Ð²Ð°Ð½Ð¸Ñ ÑÑÐ°Ð²Ð¼ ÑÐµÐ»Ð¾Ð²ÐµÐºÐ° Ð¿ÑÐ¸ Ð½Ð°ÐµÐ·Ð´Ðµ ÑÑÐ°Ð½ÑÐ¿Ð¾ÑÑÐ½ÑÐ¼Ð¸ ÑÑÐµÐ´ÑÑÐ²Ð°Ð¼Ð¸ ÑÐ°Ð·Ð»Ð¸ÑÐ½ÑÑ ÐºÐ°ÑÐµÐ³Ð¾ÑÐ¸Ð¹. ÐÑÐ¾Ð²ÐµÐ´ÐµÐ½ Ð°Ð½Ð°Ð»Ð¸Ð· Ð¾ÑÐ¸Ð±Ð¾Ðº, Ð´Ð¾Ð¿ÑÑÐºÐ°ÐµÐ¼ÑÑ ÑÐºÑÐ¿ÐµÑÑÐ°Ð¼Ð¸ Ð¿ÑÐ¸ Ð¿ÑÐ¾Ð¸Ð·Ð²Ð¾Ð´ÑÑÐ²Ðµ ÑÐºÑÐ¿ÐµÑÑÐ¸Ð·Ñ Ð¾Ð±ÑÑÐ¾ÑÑÐµÐ»ÑÑÑÐ² Ð´Ð¾ÑÐ¾Ð¶Ð½Ð¾-ÑÑÐ°Ð½ÑÐ¿Ð¾ÑÑÐ½Ð¾Ð³Ð¾ Ð¿ÑÐ¾Ð¸ÑÑÐµÑÑÐ²Ð¸Ñ Ð½Ð° Ð¿ÑÐ¸Ð¼ÐµÑÐµ ÑÐºÑÐ¿ÐµÑÑÐ½Ð¾Ð¹ Ð¿ÑÐ°ÐºÑÐ¸ÐºÐ¸, Ð° ÑÐ°ÐºÐ¶Ðµ Ð²ÑÑÐ²Ð»ÐµÐ½Ñ ÑÐµÐºÐ¾Ð¼ÐµÐ½Ð´Ð°ÑÐ¸Ð¸, Ð½Ð°Ð¿ÑÐ°Ð²Ð»ÐµÐ½Ð½ÑÐµ Ð½Ð° ÑÑÑÑÐ°Ð½ÐµÐ½Ð¸Ðµ Ð´Ð°Ð½Ð½ÑÑ Ð¾ÑÐ¸Ð±Ð¾Ðº.
description: This work contains the definition of a forensic engineering and technical examination of the circumstances of a traffic accident, the parameters characterizing the mechanism of occurrence of a traffic accident are established, the mechanism of formation of human injuries when hit by vehicles of various categories is determined. The analysis of errors made by experts during the examination of the circumstances of a traffic accident on the example of expert practice, and identified recommendations aimed at eliminating these errors.
Multi-Path and Multi-Particle Tests of Complex vs. Hyper-Complex Quantum Theory
Creators: name: Saruhan, Ece İpek
name: von Zanthier, Joachim
name: Pleinert, Marc-Oliver
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The axioms of quantum mechanics provide limited information regarding the structure of the Hilbert space, such as the underlying number system. The latter is generally regarded as complex, but generalizations of complex numbers, so-called hyper-complex numbers, cannot be ruled out in theory. Therefore, specialized experiments to test for hyper-complex quantum mechanics are needed. To date, experimental tests are limited to single-particle interference exploiting a closed phase relation in a three-path interferometer called the Peres test. The latter distinguishes complex quantum mechanics from quaternionic quantum mechanics. Here, we propose a general matrix formalism putting the Peres test on a solid mathematical ground. On this basis, we introduce multi-path and multi-particle interference tests, which provide a direct probe for any dimension of the number system of quantum mechanics.
Observation of an Inverse Turbulent-Wave Cascade in a Driven Quantum Gas
Creators: name: Karailiev, Andrey
name: Gazo, Martin
name: Gałka, Maciej
name: Eigen, Christoph
name: Satoor, Tanish
name: Hadzibabic, Zoran
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Atomic Physics (physics.atom-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We observe an inverse turbulent-wave cascade, from small to large lengthscales, in a driven homogeneous 2D Bose gas. Starting with an equilibrium condensate, we drive the gas isotropically on a lengthscale much smaller than its size, and observe a nonthermal population of modes with wavelengths larger than the drive one. At long drive times, the gas exhibits a steady nonthermal momentum distribution. At lengthscales increasing from the drive one to the system size, this distribution features in turn: (i) a power-law spectrum with an exponent close to the analytical result for a particle cascade in weak-wave turbulence, and (ii) a spectrum reminiscent of a nonthermal fixed point associated with universal coarsening in an isolated 2D gas. In further experiments, based on anisotropic driving, we reveal the complete qualitative picture of how the steady-state cascade forms.
description: Main text: 4 pages, 5 figures; Supplemental material: 1 page, 1 figure
Prediction of Room Temperature Electric Field Reversal of Magnetization in the Family of $A_4B_3\rm{O}_9$ Layered Oxides
Creators: name: Dey, Urmimala
name: McCabe, Emma E.
name: Íñiguez-González, Jorge
name: Bristowe, Nicholas C.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The promise of a strong magnetoelectric coupling in a multiferroic material is not only of fundamental interest, but also forms the basis of next generation memory devices where the direction of magnetization can be reversed by an external electric field. Using group-theory led first-principles calculations, we have identified a hitherto unknown polar phase of the $A_4B_3\rm{O}_9$ layered oxides, where the polar mode couples to the magnetic modes through a rare $Γ$-point magnetoelectric-multiferroic coupling scheme such that the net magnetization can be directly reversed by an electric field switching of the polar mode. Furthermore, in agreement with previous experimental observations, we predict room temperature magnetism in $A_4B_3\rm{O}_9$ oxides which indicates the promising practical applications of these compounds in the next generation memory devices.
Nucleosynthesis Predictions for Intermediate-Mass AGB Stars: Comparison to Observations of Type I Planetary Nebulae
Creators: name: Karakas, Amanda I.
name: van Raai, Mark A.
name: Lugaro, Maria
name: Sterling, N. C.
name: Dinerstein, Harriet L.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Type I planetary nebulae (PNe) have high He/H and N/O ratios and are thought to be descendants of stars with initial masses of ~3-8Msun. These characteristics indicate that the progenitor stars experienced proton-capture nucleosynthesis at the base of the convective envelope, in addition to the slow neutron capture process operating in the He-shell (the s-process). We compare the predicted abundances of elements up to Sr from models of intermediate-mass asymptotic giant branch (AGB) stars to measured abundances in Type I PNe. In particular, we compare predictions and observations for the light trans-iron elements Se and Kr, in order to constrain convective mixing and the s-process in these stars. A partial mixing zone is included in selected models to explore the effect of a 13C pocket on the s-process yields. The solar-metallicity models produce enrichments of [(Se, Kr)/Fe] < 0.6, consistent with Galactic Type I PNe where the observed enhancements are typically < 0.3 dex, while lower metallicity models predict larger enrichments of C, N, Se, and Kr. O destruction occurs in the most massive models but it is not efficient enough to account for the > 0.3 dex O depletions observed in some Type I PNe. It is not possible to reach firm conclusions regarding the neutron source operating in massive AGB stars from Se and Kr abundances in Type I PNe; abundances for more s-process elements may help to distinguish between the two neutron sources. We predict that only the most massive models would evolve into Type I PNe, indicating that extra-mixing processes are active in lower-mass stars (3-4Msun), if these stars are to evolve into Type I PNe.
description: 39 pages, accepted for publication in ApJ
Parametric transformations between the Heun and Gauss hypergeometric functions
Creators: name: Vidunas, Raimundas
name: Filipuk, Galina
Publisher: name: arXiv
Year: 2009
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics
subject: 33E30, 33C05

description: The hypergeometric and Heun functions are classical special functions. Transformation formulas between them are commonly induced by pull-back transformations of their differential equations, with respect to some coverings P1-to-P1. This gives expressions of Heun functions in terms of better understood hypergeometric functions. This article presents the list of hypergeometric-to-Heun pull-back transformations with a free continuous parameter, and illustrates most of them by a Heun-to-hypergeometric reduction formula. In total, 61 parametric transformations exist, of maximal degree 12.
description: One-parameter transformations added; 35 pages, 6 tables
Magnetic Branes in Third Order Lovelock-Born-Infeld Gravity
Creators: name: Dehghani, M. H.
name: Bostani, N.
name: Hendi, S. H.
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Considering both the nonlinear invariant terms constructed by the electromagnetic field and the Riemann tensor in gravity action, we obtain a new class of $(n+1)$-dimensional magnetic brane solutions in third order Lovelock-Born-Infeld gravity. This class of solutions yields a spacetime with a longitudinal nonlinear magnetic field generated by a static source. These solutions have no curvature singularity and no horizons but have a conic geometry with a deficit angle $δ$. We find that, as the Born-Infeld parameter decreases, which is a measure of the increase of the nonlinearity of the electromagnetic field, the deficit angle increases. We generalize this class of solutions to the case of spinning magnetic solutions and find that, when one or more rotation parameters are nonzero, the brane has a net electric charge which is proportional to the magnitude of the rotation parameters. Finally, we use the counterterm method in third order Lovelock gravity and compute the conserved quantities of these spacetimes. We found that the conserved quantities do not depend on the Born-Infeld parameter, which is evident from the fact that the effects of the nonlinearity of the electromagnetic fields on the boundary at infinity are wiped away. We also find that the properties of our solution, such as deficit angle, are independent of Lovelock coefficients.
description: 15 pages, one figure, references added, a subsection added
The Inevitable Future of the Starless Core Barnard 68
Creators: name: Burkert, Andreas
name: Alves, Joao
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Dense, small molecular cloud cores have been identified as the direct progenitors of stars. One of the best studied examples is Barnard 68 which is considered a prototype stable, spherical gas core, confined by a diffuse high-pressure environment. Observations of its radial density structure however indicate that Barnard 68 should be gravitationally unstable and collapsing which appears to be inconsistent with its inferred long lifetime and stability. We argue that Barnard 68 is currently experiencing a fatal collision with another small core which will lead to gravitational collapse. Despite the fact that this system is still in an early phase of interaction, our numerical simulations imply that the future gravitational collapse is already detectable in the outer surface density structure of the globule which mimicks the profile of a gravitationally unstable Bonnor-Ebert sphere. Within the next 200,000 years Barnard 68 will condense into a low-mass solar-type star(s), formed in isolation, and surrounded by diffuse, hot interstellar gas. As witnessed in situ for Barnard 68, core mergers might in general play an important role in triggering star formation and shaping the molecular core mass distribution and by that also the stellar initial mass function.
description: 7 pages, 6 figures, submitted to ApJ
Gate fidelity fluctuations and quantum process invariants
Creators: name: Magesan, Easwar
name: Blume-Kohout, Robin
name: Emerson, Joseph
Publisher: name: arXiv
Year: 2009
Subjects: subject: Quantum Physics (quant-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We characterize the quantum gate fidelity in a state-independent manner by giving an explicit expression for its variance. The method we provide can be extended to calculate all higher order moments of the gate fidelity. Using these results we obtain a simple expression for the variance of a single qubit system and deduce the asymptotic behavior for large-dimensional quantum systems. Applications of these results to quantum chaos and randomized benchmarking are discussed.
description: 13 pages, no figures, published version
Towards Real-Time Urban Physics Simulations with Digital Twins
Creators: name: Bonari, Jacopo
name: Kühn, Lisa
name: von Danwitz, Max
name: Popp, Alexander
Publisher: name: arXiv
Year: 2024
Subjects: subject: Computational Engineering, Finance, and Science (cs.CE)
subject: FOS: Computer and information sciences

description: Urban populations continue to grow, highlighting the critical need to safeguard civilians against potential disruptions, such as dangerous gas contaminant dispersion. The digital twin (DT) framework offers promise in analyzing and predicting such events. This study presents a computational framework for modelling airborne contaminant dispersion in built environments. Leveraging automatic generation of computational domains and solution processes, the proposed framework solves the underlying physical model equations with the finite element method (FEM) for numerical solutions. Model order reduction (MOR) methods are investigated to enhance computational efficiency without compromising accuracy. The study outlines the automatic model generation process, the details of the employed model, and the future perspectives for the realization of a DT. Throughout this research, the aim is to develop a reliable predictive model combining physics and data in a hybrid DT to provide informed real-time support within evacuation scenarios.
Early-type objects in NGC6611 and Eagle Nebula
Creators: name: Martayan, Christophe
name: Floquet, Michele
name: Hubert, Anne-Marie
name: Neiner, Coralie
name: Fremat, Yves
name: Baade, Dietrich
name: Fabregat, Juan
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: An important question about Be stars is whether Be stars are born as Be stars or not. It is necessary to observe young clusters to answer this question. Observations of stars in NGC6611 and the star-formation region of Eagle Nebula have been carried out with the ESO-WFI in slitless spectroscopic mode and at the VLT-GIRAFFE. The targets for the GIRAFFE observations were pre-selected from the literature and our catalogue of emission-line stars (ELS) based on the WFI study. GIRAFFE observations allowed us to study accurately the population of the early-type stars with and without emission lines. For this study, we determined the fundamental parameters of OBA stars. We also studied the status of the objects (main sequence or pre-main sequence stars) by using IR data, membership probabilities, and location in HR diagrams. The nature of the early-type ELS in M16 is derived. The slitless observations with the WFI clearly indicate a small number of ELS in M16. We observed with GIRAFFE 101 OBA stars, among them 9 are ELS with circumstellar emission in Halpha. We found that: W080 could be a new He-strong star, like W601. W301 is a possible classical Be star, W503 is a mass-transfer eclipsing binary with an accretion disk, and the other ones are possible Herbig Ae/Be stars. We also found that the rotational velocities of main sequence B stars are 18% lower than those of pre-main sequence B stars, in good agreement with theory about the evolution of rotational velocities. Combining different indications and technics, we found that 27% of the B-type stars are binaries. We also redetermined the age of NGC6611 found equal to 1.2--1.8 Myears in good agreement with the most recent determinations.
description: Accepted by A&A, english not yet corrected
Fluctuations in Spin Dynamics Excited by Pulsed Light
Creators: name: Sato, Tetsuya
name: Watanabe, Shinichi
name: Matsuo, Mamoru
name: Kato, Takeo
Publisher: name: arXiv
Year: 2024
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We theoretically investigate nonequilibrium spin fluctuations in a ferromagnet induced by a light pulse. Using a Lindblad equation consistent with the Landau-Lifshitz-Gilbert equation, we compute the autocorrelation function of magnetization. Our analysis reveals that this function comprises both thermal and nonequilibrium components. To examine the latter in detail, we introduce a Fano factor similar to nonequilibrium current noise in electronic circuits. We demonstrate that this factor encapsulates insights into the transfer of spin units to the environment. Our findings lay the groundwork for nonequilibrium spin noise spectroscopy, offering valuable insights into spin relaxation dynamics.
description: 11 pages, 3 figures
ATLAS reach for Quarkonium cross section and polarization measurement
Creators: name: Etzion, Erez
name: Ginzburg, Jony
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The ATLAS detector at CERN's LHC is preparing to take data from the first proton-proton collisions expected in the next few months. We report on the analysis of simulated data samples for production of heavy Quarkonium states J/psi and Upsilon, corresponding to an integrated luminosity of 10 pb^-1 with center of mass energy of 14 TeV expected at the early ATLAS data. We review various aspects of prompt Quarkonium production at LHC: the accessible ranges in transverse momentum and pseudorapidity, spin alignment of vector states, separation of color octet and color singlet production mechanism and feasibility of observing radiative decays Xi_c and Xi_b decays. Strategies of various measurements are outlined and methods of separating promptly produced J/psi and Upsilon mesons from various backgrounds are discussed.
description: 8 pages, 7 figures, presented at 8th International Conference on Hyperons, Charm and Beauty Hadrons, Columbia, SC, USA, 22 - 28 Jun 2008, submitted to Nuclear Physics B -- Proceeding Supplements (NUPHBP) by Elsevier
Policy Brief: Is There a New Track Two? Taking Stock of Unofficial Diplomacy in Peacemaking
Creators: name: Palmiano Federer, Julia
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 2021
Subjects: Track Two Diplomacy
Mediation
Peacebuilding
Diplomacy

description: Ottawa Dialogue's First Policy Brief by Dr Julia Palmiano Federer looks at the evolution of Track Two since it was first named in the early 1980s. Based on academic and policy scholarship on Track Two and her research on NGO mediators, Dr Palmiano Federer identifies the key ideas and concepts which have shaped the discussion of the field in this time and provides insight into where Track Two may be going.
Neuron Campaign for Initialization Guided by Information Bottleneck Theory
Creators: name: Mao, Haitao
name: Chen, Xu
name: Fu, Qiang
name: Du, Lun
name: Han, Shi
name: Zhang, Dongmei
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Initialization plays a critical role in the training of deep neural networks (DNN). Existing initialization strategies mainly focus on stabilizing the training process to mitigate gradient vanish/explosion problems. However, these initialization methods are lacking in consideration about how to enhance generalization ability. The Information Bottleneck (IB) theory is a well-known understanding framework to provide an explanation about the generalization of DNN. Guided by the insights provided by IB theory, we design two criteria for better initializing DNN. And we further design a neuron campaign initialization algorithm to efficiently select a good initialization for a neural network on a given dataset. The experiments on MNIST dataset show that our method can lead to a better generalization performance with faster convergence.
description: 5 pages, Accepted by CIKM'21
Non-LTE Spectral Analysis of Extremely Hot Post-AGB Stars: Constraints for Evolutionary Theory
Creators: name: Rauch, Thomas
name: Werner, Klaus
name: Ziegler, Marc
name: Koesterke, Lars
name: Kruk, Jeffrey W.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Spectral analysis by means of Non-LTE model-atmosphere techniques has arrived at a high level of sophistication: fully line-blanketed model atmospheres which consider opacities of all elements from H to Ni allow the reliable determination of photospheric parameters of hot, compact stars. Such models provide a crucial test of stellar evolutionary theory: recent abundance determinations of trace elements like, e.g., F, Ne, Mg, P, S, Ar, Fe, and Ni are suited to investigate on AGB nucleosynthesis. E.g., the strong Fe depletion found in hydrogen-deficient post-AGB stars is a clear indication of an efficient s-process on the AGB where Fe is transformed into Ni or even heavier trans iron-group elements. We present results of recent spectral analyses based on high-resolution UV observations of hot stars.
description: 6 pages, 2 figures
Stochastic Reservoir Computers
Creators: name: Ehlers, Peter J.
name: Nurdin, Hendra I.
name: Soh, Daniel
Publisher: name: arXiv
Year: 2024
Subjects: subject: Machine Learning (cs.LG)
subject: Neural and Evolutionary Computing (cs.NE)
subject: Systems and Control (eess.SY)
subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Physical sciences

description: Reservoir computing is a form of machine learning that utilizes nonlinear dynamical systems to perform complex tasks in a cost-effective manner when compared to typical neural networks. Many recent advancements in reservoir computing, in particular quantum reservoir computing, make use of reservoirs that are inherently stochastic. However, the theoretical justification for using these systems has not yet been well established. In this paper, we investigate the universality of stochastic reservoir computers, in which we use a stochastic system for reservoir computing using the probabilities of each reservoir state as the readout instead of the states themselves. In stochastic reservoir computing, the number of distinct states of the entire reservoir computer can potentially scale exponentially with the size of the reservoir hardware, offering the advantage of compact device size. We prove that classes of stochastic echo state networks, and therefore the class of all stochastic reservoir computers, are universal approximating classes. We also investigate the performance of two practical examples of stochastic reservoir computers in classification and chaotic time series prediction. While shot noise is a limiting factor in the performance of stochastic reservoir computing, we show significantly improved performance compared to a deterministic reservoir computer with similar hardware in cases where the effects of noise are small.
description: 34 pages, 8 figures
Multi-Frequency Progressive Refinement for Learned Inverse Scattering
Creators: name: Melia, Owen
name: Tsang, Olivia
name: Charisopoulos, Vasileios
name: Khoo, Yuehaw
name: Hoskins, Jeremy
name: Willett, Rebecca
Publisher: name: arXiv
Year: 2024
Subjects: subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Interpreting scattered acoustic and electromagnetic wave patterns is a computational task that enables remote imaging in a number of important applications, including medical imaging, geophysical exploration, sonar and radar detection, and nondestructive testing of materials. However, accurately and stably recovering an inhomogeneous medium from far-field scattered wave measurements is a computationally difficult problem, due to the nonlinear and non-local nature of the forward scattering process. We design a neural network, called Multi-Frequency Inverse Scattering Network (MFISNet), and a training method to approximate the inverse map from far-field scattered wave measurements at multiple frequencies. We consider three variants of MFISNet, with the strongest performing variant inspired by the recursive linearization method--a commonly used technique for stably inverting scattered wavefield data--that progressively refines the estimate with higher frequency content. MFISNet outperforms past methods in regimes with high-contrast, heterogeneous large objects, and inhomogeneous unknown backgrounds.
description: 31 pages, 10 figures
Long GMC Lifetimes: Using the Method and Data of Meidt et al. 2015 with A Correction
Creators: name: Koda, Jin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Meidt et al. 2015 derived short lifetimes of 20-30Myr for giant molecular clouds (GMCs) in M51. Their novel approach utilizes a decline of the GMC population during their inter-arm passage from one spiral arm to the next. Using the inter-arm travel time "t_travel" as a fiducial clock, they converted the decline rate to GMC lifetimes. They implicitly adopted zero as the pattern speed of the spiral arms, resulting in a very short t_travel. However, it is well established that the spiral arm pattern in M51 is rotating (Meidt et al. 2008, 2013), and that t_travel should be measured with respect to the rotating spiral pattern. Here we use the same method and data of Meidt et al. 2015 and re-evaluate GMC lifetimes by accounting for the pattern speed given by Meidt et al. 2013. This correction gives a longer t_travel and consequently longer GMC lifetimes of 60-500Myr.
description: RNAAS published version -- https://iopscience.iop.org/article/10.3847/2515-5172/ac2d34
Squark anti-squark pair production at the LHC: the electroweak contribution
Creators: name: Hollik, Wolfgang
name: Mirabella, Edoardo
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We present the complete NLO electroweak contribution of $\mathcal{O}(α^2_s α)$ to the production of diagonal squark--anti-squark pairs in proton--proton collisions. Compared to the lowest-order $\mathcal{O}(α_sα+ α^2)$ electroweak terms, the NLO contributions are also significant. We discuss the LO and NLO electroweak effects in cross sections and distributions at the LHC for the production of squarks different from top squarks, in various supersymmetric benchmark scenarios.
description: 38 pages, 21 figures. Replaced with the version published in JHEP
Modified Fragmentation Function in Heavy Ion Collisions at RHIC via Direct photon-Jet Measurements
Creators: name: Hamed, Ahmed M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: The presented results are the first measurements at RHIC for direct $γ$-charged hadron azimuthal correlations in heavy ion collisions. We use these correlations to study the color charge density of the medium through the medium-induced modification of high-p$_T$ parton fragmentation. Azimuthal correlations of direct photons at high transverse energy (8 $
description: 5 pages, 4 figures, 3rd International Conference on Hard and Electro- Magnetic Probes of High-Energy Nuclear Collisions
Optical to Near-IR Spectrum of a Massive Evolved Galaxy at z = 1.26
Creators: name: Matsuoka, Y.
name: Peterson, B. A.
name: Oyabu, S.
name: Kawara, K.
name: Asami, N.
name: Sameshima, H.
name: Ienaka, N.
name: Nagayama, T.
name: Tamura, M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the optical to near-infrared (IR) spectrum of the galaxy TSPS J1329-0957, a red and bright member of the class of extremely red objects (EROs) at z = 1.26. This galaxy was found in the course of the Tokyo-Stromlo Photometry Survey (TSPS) which we are conducting in the southern sky. The spectroscopic observations were carried out with the Gemini Multi-Object Spectrograph (GMOS) and the Gemini Near Infra-Red Spectrograph (GNIRS) mounted on the Gemini-South telescope. The wide wavelength coverage of 0.6 - 2.3 um provides useful clues as to the nature of EROs while most published spectra are limited to a narrower spectral range which is dictated by the need for efficient redshift determination in a large survey. We compare our spectrum with several optical composite spectra obtained in recent large surveys, and with stellar population synthesis models. The effectiveness of using near-IR broad-band data, instead of the spectral data, in deriving the galaxy properties are also investigated. We find that TSPS J1329-0957 formed when the universe was 2 - 3 Gyr old, and subsequently evolved passively to become one of the most massive galaxies found in the z = 1 - 2 universe. Its early type and estimated stellar mass of M* = 10^{11.5} Msun clearly point to this galaxy being a direct ancestor of the brightest elliptical and spheroidal galaxies in the local universe.
description: 18 pages, 4 figures. Accepted for publication in ApJ
Air entrainment in transient flows in closed water pipes: a two-layer approach
Creators: name: Bourdarias, Christian
name: Ersoy, Mehmet
name: Gerbi, Stéphane
Publisher: name: arXiv
Year: 2009
Subjects: subject: Analysis of PDEs (math.AP)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: In this paper, we first construct a model for free surface flows that takes into account the air entrainment by a system of four partial differential equations. We derive it by taking averaged values of gas and fluid velocities on the cross surface flow in the Euler equations (incompressible for the fluid and compressible for the gas). The obtained system is conditionally hyperbolic. Then, we propose a mathematical kinetic interpretation of this system to finally construct a two-layer kinetic scheme in which a special treatment for the "missing" boundary condition is performed. Several numerical tests on closed water pipes are performed and the impact of the loss of hyperbolicity is discussed and illustrated. Finally, we make a numerical study of the order of the kinetic method in the case where the system is mainly non hyperbolic. This provides a useful stability result when the spatial mesh size goes to zero.
Metallic and Insulating Phases of Repulsively Interacting Fermions in a 3D Optical Lattice
Creators: name: Schneider, U.
name: Hackermuller, L.
name: Will, S.
name: Best, Th.
name: Bloch, I.
name: Costi, T. A.
name: Helmes, R. W.
name: Rasch, D.
name: Rosch, A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The fermionic Hubbard model plays a fundamental role in the description of strongly correlated materials. Here we report on the realization of this Hamiltonian using a repulsively interacting spin mixture of ultracold $^{40}$K atoms in a 3D optical lattice. We have implemented a new method to directly measure the compressibility of the quantum gas in the trap using in-situ imaging and independent control of external confinement and lattice depth. Together with a comparison to ab-initio Dynamical Mean Field Theory calculations, we show how the system evolves for increasing confinement from a compressible dilute metal over a strongly-interacting Fermi liquid into a band insulating state. For strong interactions, we find evidence for an emergent incompressible Mott insulating phase.
description: 21 pages, 5 figures and additional supporting material
Light-induced topological phase transition with tunable layer Hall effect in axion antiferromagnets
Creators: name: Zhou, Cong
name: Zhou, Jian
Publisher: name: arXiv
Year: 2024
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The intricate interplay between light and matter provides effective tools for manipulating topological phenomena. Here, we theoretically propose and computationally show that circularly polarized light hold the potential to transform the axion insulating phase into quantum anomalous Hall state in MnBi2Te4 thin films, featuring tunable Chern numbers (ranging up to 2). In particular, we reveal the spatial rearrangement of the hidden layer-resolved anomalous Hall effect under light driven Floquet-engineering. Notably, upon Bi2Te3 layer intercalation, the anomalous Hall conductance predominantly localizes in the nonmagnetic Bi2Te3 layers that hold zero Berry curvature in the intact state, suggesting significant magnetic proximity effect. Additionally, we estimate variations in the magneto-optical Kerr effect, giving a contactless method for detecting topological transitions. Our work not only presents a strategy to investigate emergent topological phases, but also sheds light on the possible applications of the layer Hall effect in topological antiferromagnetic spintronics.
description: 5 figures, in press at Nano Letters