cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A model of reactive settling of activated sludge: comparison with experimental data
Creators: name: Bürger, Raimund
name: Careaga, Julio
name: Diehl, Stefan
name: Pineda, Romel
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: A non-negligible part of the biological reactions in the activated sludge process for treatment of wastewater takes place in secondary settling tanks that follow biological reactors. It is therefore of interest to develop models of so-called reactive settling that describe the spatial variability of reaction rates caused by the variation of local concentration of biomass due to hindered settling and compression. A reactive-settling model described by a system of nonlinear partial differential equations and a numerical scheme are introduced for the simulation of hindered settling of flocculated particles, compression at high concentrations, dispersion of the flocculated particles in the suspension, dispersion of the dissolved substrates in the fluid, and the mixing that occurs near the feed inlet. The model is fitted to experiments from a pilot plant where the sedimentation tank has a varying cross-sectional area. For the reactions, a modified version of the activated sludge model no. 1 (ASM1) is used with standard coefficients. The constitutive functions for hindered settling and compression are adjusted to a series of conventional batch settling experiments after the initial induction period of turbulence and reflocculation has been transformed away. Further (but not substantial) improvements of prediction of experimental steady-state scenarios can be achieved by also fitting additional terms modelling hydrodynamic dispersion.
Spontaneous symmetry breaking of dual-layer solitons in spin-orbit-coupled Bose-Einstein condensates
Creators: name: Chen, Zhaopin
name: Li, Yongyao
name: Liu, Yan
name: Malomed, Boris A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: It is known that stable 2D solitons of the semi-vortex (SV) and mixed-mode (MM) types are maintained by the interplay of the cubic attractive nonlinearity and spin-orbit coupling (SOC) in binary Bose-Einstein condensates. We introduce a double-layer system, in which two binary condensates, stabilized by the SOC, are linearly coupled by tunneling. By means of the numerical methods, it is found that symmetric two-layer solitons undergo the spontaneous-symmetry-breaking (SSB) bifurcation of the subcritical type. The bifurcation produces families of asymmetric 2D solitons, which exist up to the value of the total norm equal to the norm of the Townes solitons, above which the collapse occurs. This situation terminates at a critical value of the inter-layer coupling, beyond which the SSB bifurcation is absent, as the collapse sets in earlier. Symmetric 2D solitons that are destabilized by the SSB demonstrate dynamical symmetry breaking, in combination with intrinsic oscillations of the solitons, or transition to the collapse, if the soliton's norm is sufficiently large. Asymmetric MMs produced by the SSB instability start spontaneous drift, in addition to the intrinsic vibrations. Consideration of moving 2D solitons is a nontrivial problem because SOC breaks the Galilean invariance. It is found that the system supports moving MMs up to a critical value of the velocity, beyond which they undergo delocalization.
description: 17 pages, 16 figures, to be published in CNSNS
Dynamics of ethylene groups and hyperfine interactions between donor and anion molecules in $λ$-type organic conductors studied by $^{69,71}$Ga-NMR spectroscopy
Creators: name: Yasumura, N.
name: Kobayashi, T.
name: Taniguchi, H.
name: Fukuoka, S.
name: Kawamoto, A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We present the results of $^{69,71}$Ga-NMR measurements on an organic antiferromagnet $λ$-(BEDSe-TTF)$_2$GaCl$_4$ [BEDSe-TTF=bis(ethylenediseleno)tetrathiafulvalene], with comparison to reports on $λ$-(BETS)$_2$GaCl$_4$ [BETS=bis(ethylenedithio)tetraselenafulvalene] [T. Kobayashi et al., Phys. Rev. B 102, 235131 (2020)]. We found that the dynamics of two crystallographically independent ethylene groups induce two types of quadrupolar relaxation in the high-temperature region. As the ethylene motion freezes, hyperfine (HF) interactions develop between $π$ spin and Ga nuclear spin below 100 K, and thereby magnetic fluctuations of the $π$-spin system are detected even from the Ga site. The HF interaction in $λ$-(BETS)$_2$GaCl$_4$ was more than twice as large as in $λ$-(BEDSe-TTF)$_2$GaCl$_4$, implying that the short contacts between Cl atoms and the chalcogens of fulvalene part are essential for the transferred HF interaction. We propose that NMR using nuclei in anion layers is useful for studying interlayer interactions in organic conductors, which have not been studied experimentally. In addition, because the mechanism of the transferred HF interaction is considered to be the same as $π$-$d$ interaction in isostructural Fe-containing $λ$-type salts, our findings aid in the understanding of their physical properties.
description: 10 pages, 10 figures, accepted for publication in Phys. Rev. B
GiNaCDE: the high-performance F-expansion and First Integral Methods with C++ library for solving Nonlinear Differential Equations
Creators: name: Bairagi, Mithun
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Analysis of PDEs (math.AP)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We present the algorithms for three popular methods: F-expansion, modified F-expansion, and first integral methods to automatically get closed-form traveling-wave solutions of nonlinear partial differential equations (NLPDEs). We generalize and improve the methods. The proposed algorithms are manageable, straightforward, and powerful tools providing a high-performance evaluation of the exact solutions of nonlinear ordinary differential equations (NLODEs) and NLPDEs. For differential equations with parameters, the new algorithms determine the conditions on the parameters to obtain exact solutions. The algorithms show solutions to a wide variety of NLODEs and NLPDEs, both integrable and non-integrable. It can solve NLODEs and NLPDEs that contain complex functions. The algorithms are implemented in a C++ library named GiNaCDE. The efficiency and effectiveness of the algorithms are demonstrated by some examples with the help of GiNaCDE. The output results tally with the previously known results, and in some cases, new exact traveling-wave solutions are explicitly obtained. Use of the library, implementation issues, scope, limitations, and future extensions of the software are addressed.
description: 27 pages, this article presents a detailed introduction to the NLPDE solver GiNaCDE (https://doi.org/10.21105/joss.03885)
AI-enabled Sound Pattern Recognition on Asthma Medication Adherence: Evaluation with the RDA Benchmark Suite
Creators: name: Fakotakis, Nikos D.
name: Nousias, Stavros
name: Arvanitis, Gerasimos
name: Zacharaki, Evangelia I.
name: Moustakas, Konstantinos
Publisher: name: arXiv
Year: 2022
Subjects: subject: Sound (cs.SD)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Computers and Society (cs.CY)
subject: General Literature (cs.GL)
subject: Audio and Speech Processing (eess.AS)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Asthma is a common, usually long-term respiratory disease with negative impact on global society and economy. Treatment involves using medical devices (inhalers) that distribute medication to the airways and its efficiency depends on the precision of the inhalation technique. There is a clinical need for objective methods to assess the inhalation technique, during clinical consultation. Integrated health monitoring systems, equipped with sensors, enable the recognition of drug actuation, embedded with sound signal detection, analysis and identification, from intelligent structures, that could provide powerful tools for reliable content management. Health monitoring systems equipped with sensors, embedded with sound signal detection, enable the recognition of drug actuation and could be used for effective audio content analysis. This paper revisits sound pattern recognition with machine learning techniques for asthma medication adherence assessment and presents the Respiratory and Drug Actuation (RDA) Suite (https://gitlab.com/vvr/monitoring-medication-adherence/rda-benchmark) for benchmarking and further research. The RDA Suite includes a set of tools for audio processing, feature extraction and classification procedures and is provided along with a dataset, consisting of respiratory and drug actuation sounds. The classification models in RDA are implemented based on conventional and advanced machine learning and deep networks' architectures. This study provides a comparative evaluation of the implemented approaches, examines potential improvements and discusses on challenges and future tendencies.
Interior heating of rocky exoplanets from stellar flares with application to TRAPPIST-1
Creators: name: Grayver, Alexander
name: Bower, Dan J.
name: Saur, Joachim
name: Dorn, Caroline
name: Morris, Brett M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Geophysics (physics.geo-ph)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: Many stars of different spectral types with planets in the habitable zone are known to emit flares. Until now, studies that address the long-term impact of stellar flares and associated Coronal Mass Ejections (CMEs) assumed that the planet's interior remains unaffected by interplanetary CMEs, only considering the effect of plasma/UV interactions on the atmosphere of planets. Here, we show that the magnetic flux carried by flare-associated CMEs results in planetary interior heating by Ohmic dissipation and leads to a variety of interior--exterior interactions. We construct a physical model to study this effect and apply it to the TRAPPIST-1 star whose flaring activity has been constrained by Kepler observations. Our model is posed in a stochastic manner to account for uncertainty and variability in input parameters. Particularly for the innermost planets, our results suggest that the heat dissipated in the silicate mantle is both of sufficient magnitude and longevity to drive geological processes and hence facilitate volcanism and outgassing of the TRAPPIST-1 planets. Furthermore, our model predicts that Joule heating can further be enhanced for planets with an intrinsic magnetic field compared to those without. The associated volcanism and outgassing may continuously replenish the atmosphere and thereby mitigate the erosion of the atmosphere caused by the direct impact of flares and CMEs. To maintain consistency of atmospheric and geophysical models, the impact of stellar flares and CMEs on atmospheres of close-in exoplanetary systems needs to be studied in conjunction with the effect on planetary interiors.
Electric-field-driven phase transition in vanadium dioxide
Creators: name: Wu, B.
name: Zimmers, A.
name: Aubin, H.
name: Ghosh, R.
name: Liu, Y.
name: Lopez, R.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We report on local probe measurements of current-voltage and electrostatic force-voltage characteristics of electric-field-induced insulator to metal transition in VO2 thin film. In conducting AFM mode, switching from the insulating to metallic state occurs for electric-field threshold E~6.5\times10^7 Vm-1 at 300K. Upon lifting the tip above the sample surface, we find that the transition can also be observed through a change in electrostatic force and in tunneling current. In this noncontact regime, the transition is characterized by random telegraphic noise. These results show that electric field alone is sufficient to induce the transition; however, the electronic current provides a positive feedback effect that amplifies the phenomena.
Wüstite: Electric, thermodynamic and optical properties of FeO
Creators: name: Schrettle, F.
name: Kant, Ch.
name: Lunkenheimer, P.
name: Mayr, F.
name: Deisenhofer, J.
name: Loidl, A.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report on a systematic optical investigation of wüstite. In addition, the sample under consideration, Fe0.93O, has been characterized in detail by electrical transport, dielectric, magnetic and thermodynamic measurements. From infrared reflectivity experiments, phonon properties, Drude-like conductivity contributions and electronic transitions have been systematically investigated. The phonon modes reveal a clear splitting below the antiferromagnetic ordering temperature, similar to observations in other transition-metal monoxides and in spinel compounds which have been explained in terms of a spin-driven Jahn-Teller effect. The electronic transitions can best be described assuming a crystal-field parameter Dq = 750 cm-1 and a spin-orbit coupling constant λ= 95 cm-1. A well defined crystal field excitation at low temperatures reveals significant broadening on increasing temperature with an overall transfer of optical weight into dc conductivity contributions. This fact seems to indicate a melting of the on-site excitation into a Drude behavior of delocalized charge carriers. The optical band gap in wüstite is close to 1.0 eV at room temperature. With decreasing temperatures and passing the magnetic phase transition we have detected a strong blue shift of the correlation-induced band edge, which amounts more than 15% and has been rarely observed in antiferromagnets.
description: 13 pages, 10 figures
Turbulence Modeling of 3D High-speed Flows with Upstream-Informed Corrections
Creators: name: Prasad, Chitrarth
name: Gaitonde, Datta V.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Turbulence modeling has the potential to revolutionize high-speed vehicle design by serving as a co-equal partner to costly and challenging ground and flight testing. However, the fundamental assumptions that make turbulence modeling such an appealing alternative to its scale-resolved counterparts also degrade its accuracy for practical high-speed configurations, especially when fully 3D flows are considered. The current investigation develops a methodology to improve the performance of turbulence modeling for a complex Mach 8.3, 3D shock boundary layer interaction (SBLI) in a double fin geometry. A representative two-equation model, with low-Reynolds number terms, is used as a test-bed. Deficiencies in the baseline model are first elucidated using benchmark test cases involving a Mach~11.1 zero pressure gradient boundary layer and a Mach~6.17 flow over an axisymmetric compression corner. From among different possibilities, two coefficients are introduced to inhibit the non-physical over-amplification of (i) turbulence production and (ii) turbulence length-scale downstream of a shock wave. The coefficients rely on terms already present in the original model, which simplifies implementation and maintains computational costs. The values of the coefficients are predicated on the distribution of turbulence quantities upstream of the shock; this ensures that the modifications do not degrade the model predictions in simpler situations such as attached boundary layers, where they are unnecessary. The effects of the modifications are shown to result in significant improvements in surface pressure and wall heat flux for the 3D SBLI test case, which contains numerous features not observed in 2D situations, such as 3D separation, skewed boundary layers and centerline vortices. Considerations on the inflow values of turbulence variables and mesh resolution are provided.
Room temperature magnetic entropy change and magnetoresistance in La_{0.70}(Ca_{0.30-x}Sr_x)MnO_3:Ag 10% (x = 0.0-0.10)
Creators: name: Jha, R.
name: Singh, Shiva Kumar
name: Kumar, Anuj
name: Awana, V. P. S.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The magnetic and magnetocaloric properties of polycrystalline La0.70(Ca0.30-xSrx)MnO3:Ag 10% manganite have been investigated. All the compositions are crystallized in single phase orthorhombic Pbnm space group. Both, the Insulator-Metal transition temperature (TIM) and Curie temperature (Tc) are observed at 298 K for x = 0.10 composition. Though both TIM and Tc are nearly unchanged with Ag addition, the MR is slightly improved. The MR at 300 K is found to be as large as 31% with magnetic field change of 1Tesla, whereas it reaches up to 49% at magnetic field of 3Tesla for La0.70Ca0.20Sr0.10MnO3:Ag0.10 sample. The maximum entropy change (\DeltaSMmax) is 7.6 J.Kg-1.K-1 upon the magnetic field change of 5Tesla, near its Tc (300.5 K). The La0.70Ca0.20Sr0.10MnO3:Ag0.10 sample having good MR (31%1Tesla, 49%3Tesla) and reasonable change in magnetic entropy (7.6 J.Kg-1.K-1, 5 Tesla) at 300 K can be a potential magnetic refrigerant material at ambient temperatures.
description: 11 pages text + Figs comments/suggestions (awana@mail.nplindia.ernet.in)
Axisymmetric smoothed particle magneto-hydrodynamics
Creators: name: García-Senz, Domingo
name: Wissing, Robert
name: Cabezón, Rubén M.
name: Vurgun, Eda
name: Linares, Manuel
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Many astrophysical and terrestrial scenarios involving magnetic fields can be approached in axial geometry. Although the smoothed particle hydrodynamics (SPH) technique has been successfully extended to magneto-hydrodynamics (MHD), a well-verified, axisymmetric MHD scheme based on such technique does not exist yet. In this work we fill that gap in the scientific literature and propose and check a novel axisymmetric MHD hydrodynamic code, that can be applied to physical problems which display the adequate geometry. We show that the hydrodynamic code built following these axisymmetric hypothesis is able to produce similar results than standard 3D-SPMHD codes with equivalent resolution but with much lesser computational load.
description: 19 pages, 13 figures, accepted for publication in MNRAS. arXiv admin note: text overlap with arXiv:2206.05324
Quantum Hall Effects in Graphene-Based Two-Dimensional Electron Systems
Creators: name: Barlas, Yafis
name: Yang, Kun
name: MacDonald, A. H.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: In this article we review the quantum Hall physics of graphene based two-dimensional electron systems, with a special focus on recent experimental and theoretical developments. We explain why graphene and bilayer graphene can be viewed respectively as J=1 and J=2 chiral two-dimensional electron gases (C2DEGs), and why this property frames their quantum Hall physics. The current status of experimental and theoretical work on the role of electron-electron interactions is reviewed at length with an emphasis on unresolved issues in the field, including assessing the role of disorder in current experimental results. Special attention is given to the interesting low magnetic field limit and to the relationship between quantum Hall effects and the spontaneous anomalous Hall effects that might occur in bilayer graphene systems in the absence of a magnetic field.
Hard superconducting gap in germanium
Creators: name: Tosato, Alberto
name: Levajac, Vukan
name: Wang, Ji-Yin
name: Boor, Casper J.
name: Borsoi, Francesco
name: Botifoll, Marc
name: Borja, Carla N.
name: Martí-Sánchez, Sara
name: Arbiol, Jordi
name: Sammak, Amir
name: Veldhorst, Menno
name: Scappucci, Giordano
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The co-integration of spin, superconducting, and topological systems is emerging as an exciting pathway for scalable and high-fidelity quantum information technology. High-mobility planar germanium is a front-runner semiconductor for building quantum processors with spin-qubits, but progress with hybrid superconductor-semiconductor devices is hindered because obtaining a superconducting gap free of subgap states (hard gap) has proven difficult. Here we solve this challenge by developing a low-disorder, oxide-free interface between high-mobility planar germanium and a germanosilicide parent superconductor. This superconducting contact is formed by the thermally-activated solid phase reaction between a metal (Pt) and the semiconductor heterostructure (Ge/SiGe). Electrical characterization reveals near-unity transparency in Josephson junctions and, importantly, a hard induced superconducting gap in quantum point contacts. Furthermore, we demonstrate phase control of a Josephson junction and study transport in a gated two-dimensional superconductor-semiconductor array towards scalable architectures. These results expand the quantum technology toolbox in germanium and provide new avenues for exploring monolithic superconductor-semiconductor quantum circuits towards scalable quantum information processing.
Quantum Nature of Light Measured With a Single Detector
Creators: name: Steudle, Gesine A.
name: Schietinger, Stefan
name: Höckel, David
name: Dorenbos, Sander N.
name: Zwiller, Valery
name: Benson, Oliver
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We realized the most fundamental quantum optical experiment to prove the non-classical character of light: Only a single quantum emitter and a single superconducting nanowire detector were used. A particular appeal of our experiment is its elegance and simplicity. Yet its results unambiguously enforce a quantum theory for light. Previous experiments relied on more complex setups, such as the Hanbury-Brown-Twiss configuration, where a beam splitter directs light to two photodetectors, giving the false impression that the beam splitter is required. Our work results in a major simplification of the widely used photon-correlation techniques with applications ranging from quantum information processing to single-molecule detection.
description: 7 pages
Spectropolarimetry as a Means to Address Cloud Composition and Habitability for a Cloudy Exoplanetary Atmosphere in the Habitable Zone
Creators: name: West, Robert A.
name: Dumont, Philip
name: Hu, Renyu
name: Natraj, Vijay
name: Breckinridge, James
name: Chen, Pin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: FOS: Physical sciences

description: In our solar system, the densely cloud-covered atmosphere of Venus stands out as an example of how polarimetry can be used to gain information on cloud composition and particle mean radius. With current interest running high on discovering and characterizing extrasolar planets in the habitable zone where water exists in the liquid state, making use of spectropolarimetric measurements of directly-imaged exoplanets could provide key information unobtainable through other means. In principle, spectropolarimetric measurements can determine if acidity causes water activities in the clouds to be too low for life. To this end, we show that a spectropolarimeter measurement over the range 400 nm - 1000 nm would need to resolve linear polarization to a precision of about 1% or better for reflected starlight from an optically thick cloud-enshrouded exoplanet. We assess the likelihood of achieving this goal by simulating measurements from a notional spectropolarimeter as part of a starshade configuration for a large space telescope (a HabEx design, but for a 6 m diameter primary mirror). Our simulations include consideration of noise from a variety of sources. We provide guidance on limits that would need to be levied on instrumental polarization to address the science issues we discuss. For photon-limited noise, integration times would need to be of order one hour for a large radius (10 Earth radii) planet to more than 100 hours for smaller exoplanets depending on the star-planet separation, planet radius, phase angle and desired uncertainty. We discuss implications for surface chemistry and habitability.
description: ApJ, accepted
Two component spin-fermion model for high-$T_c$ cuprates: Applications to neutron scattering and ARPES experiments
Creators: name: Bang, Yunkyu
Publisher: name: arXiv
Year: 2011
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Motivated by neutron scattering experiments in the high-$T_c$ cuprates, we propose the two-component spin-fermion model as a minimal phenomenological model which has both local spins and itinerant fermions as independent degrees of freedom. Our calculations of the dynamic spin correlation function provide a successful description of the puzzling neutron experiment data and show that: (1) the upward dispersion branch of magnetic excitations is mostly due to the local spin excitations; (2) the downward dispersion branch is from collective particle-hole excitations of fermions; and (3) the resonance mode is a mixture of both degrees of freedom. Using the same model with the same set of parameters we calculated the renormalized quasiparticle dispersion and successfully reproduced one of the key features of the angle resolved photoemission spectroscopy (ARPES) experiments, i.e., the high energy kink structure in the fermion quasiparticle dispersion, hence further support the two component spin-fermion phenomenology.
description: 7 figures, 12 pages. arXiv admin note: substantial text overlap with arXiv:0706.1387
A Close-in Planet Orbiting Giant Star HD 167768
Creators: name: Teng, Huan-Yu
name: Sato, Bun'ei
name: Kunitomo, Masanobu
name: Takarada, Takuya
name: Omiya, Masashi
name: Harakawa, Hiroki
name: Xiao, Guang-Yao
name: Liu, Yu-Juan
name: Izumiura, Hideyuki
name: Kambe, Eiji
name: Yoshida, Michitoshi
name: Itoh, Yoichi
name: Ando, Hiroyasu
name: Kokubo, Eiichiro
name: Shigeru, Ida
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We report the detection of a giant planet orbiting a G-type giant star HD 167768 from radial velocity measurements using HIgh Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory (OAO). HD 167768 has a mass of $1.08_{-0.12}^{+0.14} M_{\odot}$, a radius of $9.70_{-0.25}^{+0.25} R_{\odot}$, a metallicity of $\rm{[Fe/H]}=-0.67_{-0.08}^{+0.09}$, and a surface gravity of $\log g = 2.50_{-0.06}^{+0.06}$. The planet orbiting the star is a warm Jupiter, having a period of $20.6532_{-0.0032}^{+0.0032}\ \rm{d}$, a minimum mass of $0.85_{-0.11}^{+0.12}\ M_{\rm{J}}$, and an orbital semimajor axis of $0.1512_{-0.0063}^{+0.0058}\ \rm{au}$. The planet has one of the shortest orbital periods among those ever found around deeply evolved stars ($\log g < 3.5$) using radial velocity methods. The equilibrium temperature of the planet is $1874\ \rm{K}$, as high as a hot Jupiter. The radial velocities show two additional regular variations at $41\ \rm{d}$ and $95\ \rm{d}$, suggesting the possibility of outer companions in the system. Follow-up monitoring will enable validation of the periodicity. We also calculated the orbital evolution of HD 167768 b and found that the planet will be engulfed within 0.15\,Gyr.
description: Accepted by Publications of the Astronomical Society of Japan, 9 pages, 7 figures, 2 tables
Revisiting the assignment of $1^{3}D_{1}$ meson nonet
Creators: name: Feng, Xue-Chao
name: Wei, Ke-Wei
name: Jie-Wu
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Based on the mass relations from the Regge phenomenology, we revisit the mass spectrum of $1^{3}D_{1}$ meson nonet. The masses of kaon and $s\bar{s}$ member of $1^{3}D_{1}$ ($1^{3}D_{1}(s\bar{s})$) meson nonet are obtained and the results are compared with the values from different theoretical models. Moreover, the strong decay properties of the kaon and $1^{3}D_{1}(s\bar{s})$ are presented in the $^{3}P_{0}$ model. On the basis of results, we suggest the assignment of $1^{3}D_{1}$ meson nonet need further tested in the new experiment in the future. Our results also provide mass constraints for the study of these states.
Quantum-well states at the surface of the heavy-fermion superconductor URu$_2$Si$_2$
Creators: name: Herrera-Vasco, Edwin
name: Guillamón, Isabel
name: Barrena, Víctor
name: Herrera, William
name: Galvis, Jose Augusto
name: Yeyati, Alfredo Levy
name: Rusz, Jan
name: Oppeneer, Peter M.
name: Knebel, Georg
name: Brison, Jean Pascal
name: Flouquet, Jacques
name: Aoki, Dai
name: Suderow, Hermann
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Electrons can form a two-dimensional electron gas at metal surfaces, where lateral confinement leads to quantum-well states. Such states have been observed for highly itinerant electrons, but it remains an open question whether quantum-well states can be formed from strongly correlated electrons. Here we study atomically flat terraces on surfaces of the heavy-fermion superconductor URu$_2$Si$_2$ using millikelvin scanning tunneling spectroscopy. We observe two-dimensional heavy fermions (2DHF) with an effective mass 17 times the free electron mass that form quantized states separated by a fraction of a meV. Superconductivity at the surface is induced by the bulk into the 2DHF. Our results provide a new route to realize quantum well states in correlated quantum materials.
Image segmentation by adaptive distance based on EM algorithm
Creators: name: Mahjoub, Mohamed Ali
name: kalti, karim
Publisher: name: arXiv
Year: 2012
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: This paper introduces a Bayesian image segmentation algorithm based on finite mixtures. An EM algorithm is developed to estimate parameters of the Gaussian mixtures. The finite mixture is a flexible and powerful probabilistic modeling tool. It can be used to provide a model-based clustering in the field of pattern recognition. However, the application of finite mixtures to image segmentation presents some difficulties; especially it's sensible to noise. In this paper we propose a variant of this method which aims to resolve this problem. Our approach proceeds by the characterization of pixels by two features: the first one describes the intrinsic properties of the pixel and the second characterizes the neighborhood of pixel. Then the classification is made on the base on adaptive distance which privileges the one or the other features according to the spatial position of the pixel in the image. The obtained results have shown a significant improvement of our approach compared to the standard version of EM algorithm.
description: 6 pages
On the theory of disc photoevaporation
Creators: name: Owen, James E.
name: Clarke, Cathie J.
name: Ercolano, Barbara
Publisher: name: arXiv
Year: 2011
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We discuss a hydrodynamical model for the dispersal of protoplanetary discs around young, low mass (<1.5 M_sun) stars by photoevaporation from the central object's energetic radiation, which considers the far-ultraviolet as well as the X-ray component of the radiation field. We present analytical scaling relations and derive estimates for the total mass-loss rates, as well as discussing the existence of similarity solutions for flows from primordial discs and discs with inner holes. Furthermore, we perform numerical calculations, which span a wide range of parameter space and allow us to provide accurate scalings of the mass-loss rates with the physical parameters of the systems (X-ray and FUV luminosity, stellar mass, disc mass, disc temperature and inner hole radius). The model suggest that the X-ray component dominates the photoevaporative mass-loss rates from the inner disc. The mass-loss rates have values in the range from 10e-11 to 10e-7 M_sun/yr and scale linearly with X-ray luminosity, with only a weak dependence on the other parameters explored. However, in the case of high FUV to X-ray (L_FUV/L_X>100) luminosity ratios, the FUV constricts the X-ray flow and may dominate the mass-loss. Simulations of low mass discs with inner holes demonstrate a further stage of disc clearing, which we call `thermal sweeping'. This process occurs when the mid-plane pressure drops to sufficiently low values. At this stage a bound, warm, X-ray heated region becomes sufficiently large and unstable, such that the remaining disc material is cleared on approximately dynamical time-scales. This process significantly reduces the time taken to clear the outer regions of the disc, resulting in an expected transition disc population that will be dominated by accreting objects, as indicated by recent observations.
description: Accepted MNRAS, 25 pages
A deterministic view on explicit data-driven (M)PC
Creators: name: Klädtke, Manuel
name: Teichrib, Dieter
name: Schlüter, Nils
name: Darup, Moritz Schulze
Publisher: name: arXiv
Year: 2022
Subjects: subject: Systems and Control (eess.SY)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: We show that the explicit realization of data-driven predictive control (DPC) for linear deterministic systems is more tractable than previously thought. To this end, we compare the optimal control problems (OCP) corresponding to deterministic DPC and classical model predictive control (MPC), specify its close relation, and systematically eliminate ambiguity inherent in DPC. As a central result, we find that the explicit solutions to these types of DPC and MPC are of exactly the same complexity. We illustrate our results with two numerical examples highlighting features of our approach.
description: 7 pages, 2 figure, submitted to 61st IEE Conference on Decision and Control 2022
Entanglement dynamics of coupled quantum oscillators in independent nonMarkovian baths
Creators: name: Hsiang, Jen-Tsung
name: Arısoy, Onat
name: Hu, Bei-Lok
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: This work strives to better understand how the entanglement in an open quantum system, here represented by two coupled Brownian oscillators, is affected by a nonMarkovian environment (with memories), here represented by two independent baths each oscillator separately interacts with. We consider two settings, a `symmetric' configuration wherein the parameters of both oscillators and their baths are identical, and an `asymmetric' configuration wherein they are different, in particular, a `hybrid' configuration, where one of the two coupled oscillators interacts with a nonMarkovian bath and the other with a Markovian bath. We ask two groups of questions: Q1) Which time regime does the bath's nonMarkovianity benefit the system's entanglement most? The answers we get from detailed numerical studies suggest that A1) For an initially entangled pair of oscillators, we see that in the intermediate time range, the duration of entanglement is proportional to the memory time, and it lasts a fraction of the relaxation time, but at late times when the dynamics reaches a steady state, the value of the symplectic eigenvalue of the partially transposed covariance matrix barely benefit from the bath nonMarkovianity. For the second group of questions: Q2)Can the memory of one nonMarkovian bath be passed on to another Markovian bath? And if so, does this memory transfer help to sustain the system's entanglement dynamics? Our results from numerical studies of the asymmetric hybrid configuration indicate that A2) A system with a short memory time can acquire improvement when it is coupled to another system with a long memory time, but, at a cost of the latter. The sustainability of the bipartite entanglement is determined by the party which breaks off entanglement most easily.
description: 31 pages, 10 figures
Mitigating radio frequency interference in CHIME/FRB real-time intensity data
Creators: name: Rafiei-Ravandi, Masoud
name: Smith, Kendrick M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Extragalactic fast radio bursts (FRBs) are a new class of astrophysical transients with unknown origins that have become a main focus of radio observatories worldwide. FRBs are highly energetic ($\sim 10^{36}$-$10^{42}$ ergs) flashes that last for about a millisecond. Thanks to its broad bandwidth (400-800 MHz), large field of view ($\sim$200 sq. deg.), and massive data rate (1500 TB of coherently beamformed data per day), the Canadian Hydrogen Intensity Mapping Experiment / Fast Radio Burst (CHIME/FRB) project has increased the total number of discovered FRBs by over a factor 10 in 3 years of operation. CHIME/FRB observations are hampered by the constant exposure to radio frequency interference (RFI) from artificial devices (e.g., cellular phones, aircraft), resulting in $\sim$20% loss of bandwidth. In this work, we describe our novel technique for mitigating RFI in CHIME/FRB real-time intensity data. We mitigate RFI through a sequence of iterative operations, which mask out statistical outliers from frequency-channelized intensity data that have been effectively high-pass filtered. Keeping false positive and false negative rates at very low levels, our approach is useful for any high-performance surveys of radio transients in the future.
description: 12 pages, 5 figures, 3 tables, published in ApJS
Subsurface Depths Structure Maps Reconstruction with Generative Adversarial Networks
Creators: name: Ivlev, Dmitry
Publisher: name: arXiv
Year: 2022
Subjects: subject: Geophysics (physics.geo-ph)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: This paper described a method for reconstruction of detailed-resolution depth structure maps, usually obtained after the 3D seismic surveys, using the data from 2D seismic depth maps. The method uses two algorithms based on the generative-adversarial neural network architecture. The first algorithm StyleGAN2-ADA accumulates in the hidden space of the neural network the semantic images of mountainous terrain forms first, and then with help of transfer learning, in the ideal case - the structure geometry of stratigraphic horizons. The second algorithm, the Pixel2Style2Pixel encoder, using the semantic level of generalization of the first algorithm, learns to reconstruct the original high-resolution images from their degraded copies (super-resolution technology). There was demonstrated a methodological approach to transferring knowledge on the structural forms of stratigraphic horizon boundaries from the well-studied areas to the underexplored ones. Using the multimodal synthesis of Pixel2Style2Pixel encoder, it is proposed to create a probabilistic depth space, where each point of the project area is represented by the density of probabilistic depth distribution of equally probable reconstructed geological forms of structural images. Assessment of the reconstruction quality was carried out for two blocks. Using this method, credible detailed depth reconstructions comparable with the quality of 3D seismic maps have been obtained from 2D seismic maps.
description: 12 pages, 12 figures, 1 table
Giant ambipolar Rashba effect in a semiconductor: BiTeI
Creators: name: Crepaldi, A.
name: Moreschini, L.
name: Autès, G.
name: Tournier-Colletta, C.
name: Moser, S.
name: Virk, N.
name: Berger, H.
name: Bugnon, Ph.
name: Chang, Y. J.
name: Kern, K.
name: Bostwick, A.
name: Rotenberg, E.
name: Yazyev, O. V.
name: Grioni, M.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We observe a giant spin-orbit splitting in bulk and surface states of the non-centrosymmetric semiconductor BiTeI. We show that the Fermi level can be placed in the valence or in the conduction band by controlling the surface termination. In both cases it intersects spin-polarized bands, in the corresponding surface depletion and accumulation layers. The momentum splitting of these bands is not affected by adsorbate-induced changes in the surface potential. These findings demonstrate that two properties crucial for enabling semiconductor-based spin electronics -- a large, robust spin splitting and ambipolar conduction -- are present in this material.
description: 4 pages, 3 figures
Low-Cost Beamforming and DOA Estimation Based on One-Bit Reconfigurable Intelligent Surface
Creators: name: Yang, Zihan
name: Chen, Peng
name: Guo, Ziyu
name: Ni, Dahai
Publisher: name: arXiv
Year: 2022
Subjects: subject: Signal Processing (eess.SP)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: In this work, we consider the Direction-of-Arrival (DOA) estimation problem in a low-cost architecture where only one antenna as the receiver is aided by a reconfigurable intelligent surface (RIS). We introduce the one-bit RIS as a signal reflector to enhance signal transmission in non-line-of-sight (NLOS) situations and substantially simplify the physical hardware for DOA estimation. We optimize the beamforming scheme called measurement matrix to focus the echo power on the receiver with the coarse localization information of the targets as the prior. A beamforming scheme based on the modified genetic algorithm is proposed to optimize the measurement matrix, guaranteeing restricted isometry property (RIP) and meeting single beamforming requirements. The DOA results are finely estimated by solving an atomic-norm based sparse reconstruction problem. Simulation results show that the proposed method outperforms the existing methods in the DOA estimation performance.
description: 5 pages, 8 figures
Bayesian Learning of Parameterised Quantum Circuits
Creators: name: Duffield, Samuel
name: Benedetti, Marcello
name: Rosenkranz, Matthias
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: Machine Learning (stat.ML)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Currently available quantum computers suffer from constraints including hardware noise and a limited number of qubits. As such, variational quantum algorithms that utilise a classical optimiser in order to train a parameterised quantum circuit have drawn significant attention for near-term practical applications of quantum technology. In this work, we take a probabilistic point of view and reformulate the classical optimisation as an approximation of a Bayesian posterior. The posterior is induced by combining the cost function to be minimised with a prior distribution over the parameters of the quantum circuit. We describe a dimension reduction strategy based on a maximum a posteriori point estimate with a Laplace prior. Experiments on the Quantinuum H1-2 computer show that the resulting circuits are faster to execute and less noisy than the circuits trained without the dimension reduction strategy. We subsequently describe a posterior sampling strategy based on stochastic gradient Langevin dynamics. Numerical simulations on three different problems show that the strategy is capable of generating samples from the full posterior and avoiding local optima.
description: 11 pages, 7 figures
Photometric detection of internal gravity waves in upper main-sequence stars. III. Comparison of amplitude spectrum fitting and Gaussian process regression using celerite2
Creators: name: Bowman, Dominic M.
name: Dorn-Wallenstein, Trevor Z.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Studies of massive stars using space photometry have revealed that they commonly exhibit stochastic low-frequency (SLF) variability. This has been interpreted as being caused by internal gravity waves (IGWs) excited at the interface of convective and radiative regions within stellar interiors, such as the convective core or sub-surface convection zones. We aim to compare the properties of SLF variability in massive main-sequence stars observed by the TESS mission determined by different statistical methods, and confirm the correlation between the morphology of SLF variability and a star's location in the HR diagram. From a sample of 30 massive stars observed by TESS, we compare the resultant parameters of SLF variability, in particular the characteristic frequency, obtained from fitting the amplitude spectrum of the light curve with those inferred from fitting the covariance structure of the light curve using the celerite2 Gaussian process (GP) regression software and a damped SHO kernel. We find a difference in the characteristic frequency obtained from the amplitude spectrum fitting and from fitting the co-variance structure of the light curve using a GP regression with celerite2 for only a minority of the considered sample. However, the trends among mass, age and the properties of SLF variability previously reported remain unaffected. GP regression is a useful and novel methodology to efficiently characterise SLF variability in massive stars compared to previous techniques used in the literature. We conclude that the correlation between a star's SLF variability, in particular the characteristic frequency, and its location in the HR diagram is robust for main-sequence massive stars. There also exists a distribution in the stochasticity of SLF variability in massive stars, which indicates that the coherency of SLF variability is also a function of mass and age in massive stars.
description: 18 pages, accepted for publication in A&A
Superconductivity at 5.2 K in ZrTe3 polycrystals and the effect of Cu, Ag intercalation
Creators: name: Yadav, C. S.
name: Paulose, P. L.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We report the occurrence of superconductivity in polycrystalline samples of ZrTe3 at 5.2 K temperature at ambient pressure. The superconducting state coexists with the charge density wave (CDW) phase, which sets in at 63K. The intercalation of Cu or Ag, does not have any bearing on the superconducting transition temperature but suppresses the CDW state. The feature of CDW anomaly in these compounds is clearly seen in the DC magnetization data. Resistivity data is analysed to estimate the relative loss of carriers and reduction in the nested Fermi surface area upon CDW formation in the ZrTe3 and the intercalated compounds.
description: 5 pages, 8 figures