cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
ChatGPT in the classroom. Exploring its potential and limitations in a Functional Programming course
Creators: name: Popovici, Dan-Matei
Publisher: name: arXiv
Year: 2024
Subjects: subject: Human-Computer Interaction (cs.HC)
subject: FOS: Computer and information sciences

description: In November 2022, OpenAI has introduced ChatGPT, a chatbot based on supervised and reinforcement learning. Not only can it answer questions emulating human-like responses, but it can also generate code from scratch or complete coding templates provided by the user. ChatGPT can generate unique responses which render any traditional anti-plagiarism tool useless. Its release has ignited a heated debate about its usage in academia, especially by students. We have found, to our surprise, that our students at POLITEHNICA University of Bucharest (UPB) have been using generative AI tools (ChatGPT and its predecessors) for solving homework, for at least 6 months. We therefore set out to explore the capabilities of ChatGPT and assess its value for educational purposes. We solved all our coding assignments for the semester from our UPB Functional Programming course. We discovered that, although ChatGPT provides correct answers in 68% of the cases, only around half of those are legible solutions which can benefit students in some form. On the other hand, ChatGPT has a very good ability to perform code review on student programming homework. Based on these findings, we discuss the pros and cons of ChatGPT in education.
Exchange magnon induced resistance asymmetry in permalloy spin-Hall oscillators
Creators: name: Langenfeld, S.
name: Tshitoyan, V.
name: Fang, Z.
name: Wells, A.
name: Moore, T. A.
name: Ferguson, A. J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We investigate magnetization dynamics in a spin-Hall oscillator using a direct current measurement as well as conventional microwave spectrum analysis. When the current applies an anti-damping spin-transfer torque, we observe a change in resistance which we ascribe to the excitation of incoherent exchange magnons. A simple model is developed based on the reduction of the effective saturation magnetization, quantitatively explaining the data. The observed phenomena highlight the importance of exchange magnons on the operation of spin-Hall oscillators.
description: 4 pages, 4 figures
Anomalies in Weak Decays of Hadrons Containing a b Quark
Creators: name: Issadykov, Aidos
name: Ivanov, Mikhail A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: A brief review of the current state of observed deviations of theoretical predictions from experimental data in semileptonic decays of $B$ and $B_c$ mesons is given. A theoretical analysis of these decays is carried out, taking into account the effects of new physics, which appear due to the introduction of new four-fermion operators, which are absent in the basis of the Standard Model (SM) operators. The necessary form factors are calculated within the framework of the covariant quark model developed in our papers.
description: Contribution to: International Conference on Quantum Field Theory, High-Energy Physics, and Cosmology
Double-Averaging Can Fail to Characterize the Long-Term Evolution of Lidov-Kozai Cycles & Derivation of an Analytical Correction
Creators: name: Luo, Liantong
name: Katz, Boaz
name: Dong, Subo
Publisher: name: arXiv
Year: 2016
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The double-averaging (DA) approximation is widely employed as the standard technique in studying the secular evolution of the hierarchical three-body system. We show that effects stemmed from the short-timescale oscillations ignored by DA can accumulate over long timescales and lead to significant errors in the long-term evolution of the Lidov-Kozai cycles. In particular, the conditions for having an orbital flip, where the inner orbit switches between prograde and retrograde with respect to the outer orbit and the associated extremely high eccentricities during the switch, can be modified significantly. The failure of DA can arise for a relatively strong perturber where the mass of the tertiary is considerable compared to the total mass of the inner binary. This issue can be relevant for astrophysical systems such as stellar triples, planets in stellar binaries, stellar-mass binaries orbiting massive black holes and moons of the planets perturbed by the Sun. We derive analytical equations for the short-term oscillations of the inner orbit to the leading order for all inclinations, eccentricities and mass ratios. Under the test particle approximation, we derive the "corrected double-averaging" (CDA) equations by incorporating the effects of short-term oscillations into the DA. By comparing to N-body integrations, we show that the CDA equations successfully correct most of the errors of the long-term evolution under the DA approximation for a large range of initial conditions. We provide an implementation of CDA that can be directly added to codes employing DA equations.
description: Fig. 3 and Eq. 35 corrected; Matlab codes included as ancillary files
Optimal 5-step nilpotent quadratic algebras
Creators: name: Iyudu, Natalia
name: Shkarin, Stanislav
Publisher: name: arXiv
Year: 2015
Subjects: subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: 17A45, 16A22

description: By the Golod--Shafarevich Theorem, an associative algebra R given by n generators and d
3D Weak Lensing: Modified Theories of Gravity
Creators: name: Pratten, Geraint
name: Munshi, Dipak
name: Valageas, Patrick
name: Brax, Philippe
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Weak lensing (WL) promises to be a particularly sensitive probe of both the growth of large scale structure (LSS) as well as the fundamental relation between matter density perturbations and metric perturbations, thus providing a powerful tool with which we may constrain modified theories of gravity (MG) on cosmological scales. Future deep, wide-field WL surveys will provide an unprecedented opportunity to constrain deviations from General Relativity (GR). Employing a three-dimensional (3D) analysis based on the spherical Fourier-Bessel (sFB) expansion, we investigate the extent to which MG theories will be constrained by a typical 3D WL survey configuration including noise from the intrinsic ellipticity distribution $σ_ε$ of source galaxies. Here we focus on two classes of screened theories of gravity: i) $f(R)$ chameleon models and ii) environmentally dependent dilaton models. We use one-loop perturbation theory combined with halo models in order to accurately model the evolution of matter power-spectrum with redshift in these theories. Using a Fisher information matrix based approach, we show that for an all-sky spectroscopic survey, the parameter $f_{R_0}$ can be constrained in the range $f_{R_0}< 5\times 10^{-6}(9\times 10^{-6})$ for $n=1(2)$ with a 3$σ$ confidence level. This can be achieved by using relatively low order angular harmonics $\ell<100$. Including higher order harmonics $\ell>100$ can further tighten the constraints, making them comparable to current solar-system constraints. We also employ a Principal Component Analysis (PCA) in order to study the parameter degeneracies in the MG parameters. Our results can trivially be extended to other MG theories, such as the K-mouflage models. The confusion from intrinsic ellipticity correlation and modification of the matter power-spectrum at small scale due to feedback mechanisms is briefly discussed.
description: 25 pages. 10 Figures. 4 Tables. Submitted to PRD
LRPD: Large Replay Parallel Dataset
Creators: name: Yakovlev, Ivan
name: Melnikov, Mikhail
name: Bukhal, Nikita
name: Makarov, Rostislav
name: Alenin, Alexander
name: Torgashov, Nikita
name: Okhotnikov, Anton
Publisher: name: arXiv
Year: 2023
Subjects: subject: Audio and Speech Processing (eess.AS)
subject: Sound (cs.SD)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: The latest research in the field of voice anti-spoofing (VAS) shows that deep neural networks (DNN) outperform classic approaches like GMM in the task of presentation attack detection. However, DNNs require a lot of data to converge, and still lack generalization ability. In order to foster the progress of neural network systems, we introduce a Large Replay Parallel Dataset (LRPD) aimed for a detection of replay attacks. LRPD contains more than 1M utterances collected by 19 recording devices in 17 various environments. We also provide an example training pipeline in PyTorch [1] and a baseline system, that achieves 0.28% Equal Error Rate (EER) on evaluation subset of LRPD and 11.91% EER on publicly available ASVpoof 2017 [2] eval set. These results show that model trained with LRPD dataset has a consistent performance on the fully unknown conditions. Our dataset is free for research purposes and hosted on GDrive. Baseline code and pre-trained models are available at GitHub.
Ultraviolet Fe II Emission in Fainter Quasars: Luminosity Dependences, and the Influence of Environments
Creators: name: Clowes, Roger G.
name: Haberzettl, Lutz
name: Raghunathan, Srinivasan
name: Williger, Gerard M.
name: Mitchell, Sophia M.
name: Soechting, Ilona K.
name: Graham, Matthew J.
name: Campusano, Luis E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We investigate the strength of ultraviolet Fe II emission in fainter quasars compared with brighter quasars for 1.0 <= z <= 1.8, using the SDSS (Sloan Digital Sky Survey) DR7QSO catalogue and spectra of Schneider et al., and the SFQS (SDSS Faint Quasar Survey) catalogue and spectra of Jiang et al. We quantify the strength of the UV Fe II emission using the W2400 equivalent width of Weymann et al., which is defined between two rest-frame continuum windows at 2240-2255 and 2665-2695 Ang. The main results are the following. (1) We find that for W2400 >~ 25 Ang. there is a universal (i.e. for quasars in general) strengthening of W2400 with decreasing intrinsic luminosity, L3000. (2) In conjunction with previous work by Clowes et al., we find that there is a further, differential, strengthening of W2400 with decreasing L3000 for those quasars that are members of Large Quasar Groups (LQGs). (3) We find that increasingly strong W2400 tends to be associated with decreasing FWHM of the neighbouring Mg II λ2798 broad emission line. (4) We suggest that the dependence of W2400 on L3000 arises from Lyα fluorescence. (5) We find that stronger W2400 tends to be associated with smaller virial estimates from Shen et al. of the mass of the central black hole, by a factor ~ 2 between the ultrastrong emitters and the weak. Stronger W2400 emission would correspond to smaller black holes that are still growing. The differential effect for LQG members might then arise from preferentially younger quasars in the LQG environments.
description: Accepted for publication in MNRAS. 21 pages, 11 figures
Accuracy of ALMA estimates of young disk radii and masses. Predicted observations from numerical simulations
Creators: name: Tung, Ngo-Duy
name: Testi, Leonardo
name: Lebreuilly, Ugo
name: Hennebelle, Patrick
name: Maury, Anaëlle
name: Klessen, Ralf S.
name: Cacciapuoti, Luca
name: González, Matthias
name: Rosotti, Giovanni
name: Molinari, Sergio
Publisher: name: arXiv
Year: 2024
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Protoplanetary disks, which are the natural consequence of the gravitational collapse of the dense molecular cloud cores, host the formation of the known planetary systems in our universe. Substantial efforts have been dedicated to investigating the properties of these disks in the more mature Class II stage, either via numerical simulations of disk evolution from a limited range of initial conditions or observations of their dust continuum and line emission from specific molecular tracers. The results coming from these two standpoints have been used to draw comparisons. However, few studies have investigated the main limitations at work when measuring the embedded Class 0/I disk properties from observations, especially in a statistical fashion. In this study, we provide a first attempt to compare the accuracy of some critical disk parameters in Class 0/I systems, as derived on real ALMA observational data, with the corresponding physical parameters that can be directly defined by theoreticians and modellers in numerical simulations. The approach we follow here is to provide full post-processing of the numerical simulations and apply it to the synthetic observations the same techniques used by observers to derive the physical parameters. We performed 3D Monte Carlo radiative transfer and mock interferometric observations of the disk populations formed in a magnetohydrodynamic (MHD) simulation model of disk formation through the collapse of massive clumps with the tools \textsc{Radmc-3d} and \textsc{Casa}, respectively, to obtain their synthetic observations. With these observations, we re-employed the techniques commonly used in disk modelling from their continuum emissions to infer the properties that would most likely be obtained with real interferometers. We then demonstrated how these properties may vary with respect to the gas kinematics analyses and dust continuum modelling.
description: Accepted for publication in Astronomy & Astrophysics, 32 pages, 28 figures
Accreting luminous low-mass planets escape from migration traps at pressure bumps
Creators: name: Chrenko, O.
name: Chametla, R. O.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We investigate the migration of Mars- to super-Earth-sized planets in the vicinity of a pressure bump in a 3D radiative protoplanetary disc while accounting for the effect of accretion heat release. Pressure bumps have often been assumed to act as efficient migration traps, but we show that the situation changes when the thermal forces are taken into account. Our simulations reveal that for planetary masses $\lesssim$$2\,M_{\oplus}$, once their luminosity exceeds the critical value predicted by linear theory, thermal driving causes their orbits to become eccentric, quenching the positive corotation torque responsible for the migration trap. As a result, planets continue migrating inwards past the pressure bump. Additionally, we find that planets that remain circular and evolve in the super-Keplerian region of the bump exhibit a reversed asymmetry of their thermal lobes, with the heating torque having an opposite (negative) sign compared to the standard circular case, thus leading to inward migration as well. We also demonstrate that the super-critical luminosities of planets in question can be reached through the accretion of pebbles accumulating in the bump. Our findings have implications for planet formation scenarios that rely on the existence of migration traps at pressure bumps, as the bumps may repeatedly spawn inward-migrating low-mass embryos rather than harbouring newborn planets until they become massive.
description: Accepted in MNRAS
Rapid rotational crust-core relaxation in magnetars
Creators: name: Sedrakian, Armen
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: If a magnetar interior $B$-field exceeds $10^{15}$~G, it will unpair the proton superconductor in the stellar core by inducing diamagnetic currents that destroy the Cooper pair coherence. Then, the $P$-wave neutron superfluid in these non-superconducting regions will couple to the stellar plasma by scattering of protons off the quasiparticles that are confined in the cores of neutron vortices by the strong (nuclear) force. The dynamical timescales associated with this interaction span from several minutes at the crust-core interface to a few seconds in the deep core. We show that (a) the rapid crust-core coupling is incompatible with oscillation models of magnetars that completely decouple the core superfluid from the crust and (b) magnetar precession is damped by the coupling of normal fluids to the superfluid core and, if observed, needs to be forced or continuously excited by seismic activity.
description: v2: minor editorial changes, final version, 5 pages, 3 figures
Proceedings of the Fourteenth International Symposium on Games, Automata, Logics, and Formal Verification
Creators: name: Achilleos, Antonis
name: Della Monica, Dario
Publisher: name: arXiv
Year: 2023
Subjects: subject: Formal Languages and Automata Theory (cs.FL)
subject: Computational Complexity (cs.CC)
subject: Logic in Computer Science (cs.LO)
subject: FOS: Computer and information sciences

description: This volume contains the proceedings of the 14th International Symposium on Games, Automata, Logics, and Formal Verification (GandALF 2023). The aim of GandALF 2023 symposium is to bring together researchers from academia and industry who are actively working in the fields of Games, Automata, Logics, and Formal Verification. The idea is to cover an ample spectrum of themes, ranging from theory to applications, and stimulate cross-fertilization.
Differential Analysis of Triggers and Benign Features for Black-Box DNN Backdoor Detection
Creators: name: Fu, Hao
name: Krishnamurthy, Prashanth
name: Garg, Siddharth
name: Khorrami, Farshad
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cryptography and Security (cs.CR)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: This paper proposes a data-efficient detection method for deep neural networks against backdoor attacks under a black-box scenario. The proposed approach is motivated by the intuition that features corresponding to triggers have a higher influence in determining the backdoored network output than any other benign features. To quantitatively measure the effects of triggers and benign features on determining the backdoored network output, we introduce five metrics. To calculate the five-metric values for a given input, we first generate several synthetic samples by injecting the input's partial contents into clean validation samples. Then, the five metrics are computed by using the output labels of the corresponding synthetic samples. One contribution of this work is the use of a tiny clean validation dataset. Having the computed five metrics, five novelty detectors are trained from the validation dataset. A meta novelty detector fuses the output of the five trained novelty detectors to generate a meta confidence score. During online testing, our method determines if online samples are poisoned or not via assessing their meta confidence scores output by the meta novelty detector. We show the efficacy of our methodology through a broad range of backdoor attacks, including ablation studies and comparison to existing approaches. Our methodology is promising since the proposed five metrics quantify the inherent differences between clean and poisoned samples. Additionally, our detection method can be incrementally improved by appending more metrics that may be proposed to address future advanced attacks.
description: Published in the IEEE Transactions on Information Forensics and Security
Multi-level adaptive particle refinement method with large refinement scale ratio and new free-surface detection algorithm for complex fluid-structure interaction problems
Creators: name: Gao, Tianrun
name: Qiu, Huihe
name: Fu, Lin
Publisher: name: arXiv
Year: 2023
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences
subject: 76B07, 76M28, 76T10, 35Q70, 82C22

description: Fluid-Structure Interaction (FSI) is a crucial problem in ocean engineering. The smoothed particle hydrodynamics (SPH) method has been employed recently for FSI problems in light of its Lagrangian nature and its advantage in handling multi-physics problems. The efficiency of SPH can be greatly improved with the Adaptive Particle Refinement (APR) method, which refines particles in the regions of interest while deploying coarse particles in the left areas. In this study, the APR method is further improved by developing several new algorithms. Firstly, a new particle refinement strategy with the refinement scale ratio of 4 is employed for multi-level resolutions, and this dramatically decreases the computational costs compared to the standard APR method. Secondly, the regularized transition sub-zone is deployed to render an isotropic particle distribution, which makes the solutions between the refinement zone and the non-refinement zone smoother and consequently results in a more accurate prediction. Thirdly, for complex FSI problems with free surface, a new free-surface detection method based on the Voronoi diagram is proposed, and the performance is validated in comparison to the conventional method. The improved APR method is then applied to a set of challenging FSI cases. Numerical simulations demonstrate that the results from the refinement with scale ratio 4 are consistent with other studies and experimental data, and also agree well with those employing the refinement scale ratio 2. A significant reduction in the computational time is observed for all the considered cases. Overall, the improved APR method with a large refinement scale ratio and the new free-surface detection strategy shows great potential in simulating complex FSI problems efficiently and accurately.
description: 47 pages, 26 figures, accepted to be published by Journal of Computational Physics
Alterations in electroosmotic slip velocity: combined effect of viscoelasticity and surface potential undulation
Creators: name: Mahapatra, Bimalendu
name: Bandopadhyay, Aditya
Publisher: name: arXiv
Year: 2023
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: In computational models of microchannel flows, the Helmholtz-Smoluchowski slip velocity boundary condition is often used because it approximates the motion of the electric double layer without resolving the charge density profiles close to the walls while drastically reducing the computational effort needed for the flow model to be solved. Despite working well for straight channel flow of Newtonian fluids, the approximation does not work well for flow involving complex fluids and spatially varying surface potential distribution. To treat these effects using the slip velocity boundary condition, it is necessary to understand how the surface potential and fluid properties affect the slip velocity. The present analysis shows the existence of a modified electroosmotic slip velocity for viscoelastic fluids, which is strongly dependent upon Deborah number and viscosity ratio, and this modification differs significantly from the slip velocity of Newtonian fluids. An augmentation of fluid elasticity results in an asymmetric distribution of slip velocity. Nonintuitively, the modulation wavelength of the imposed surface potential contributes to changing the slip velocity magnitude and adding periodicity to the solution. The proposed electroosmotic slip velocity for viscoelastic fluid can be used in computational models of microchannel flows to approximate the motion of the electric double layer without resolving the charge density profiles close to the walls.
description: 18 pages
Science with the Global Cosmic-ray Observatory (GCOS)
Creators: name: Batista, Rafael Alves
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: High Energy Physics - Experiment (hep-ex)
subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: The Global Cosmic-ray Observatory (GCOS) is a proposed large-scale observatory for studying ultra-high-energy cosmic particles, including ultra-high-energy cosmic rays (UHECRs), photons, and neutrinos. Its primary goal is to characterise the properties of the highest-energy particles in Nature with unprecedented accuracy, and to identify their elusive sources. With an aperture at least a ten-fold larger than existing observatories, this next-generation facility should start operating after 2030, when present-day detectors will gradually cease their activities. Here we briefly review the scientific case motivating GCOS. We present the status of the project, preliminary ideas for its design, and some estimates of its capabilities.
description: Presented at the 38th International Cosmic Ray Conference (ICRC2023)
Tidal disruption jets of supermassive black holes as hidden sources of cosmic rays: explaining the IceCube TeV-PeV neutrinos
Creators: name: Wang, Xiang-Yu
name: Liu, Ruo-Yu
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Cosmic ray interactions that produce high-energy neutrinos also inevitably generate high-energy gamma rays, which finally contribute to the diffuse high-energy gamma-ray background after they escape the sources. It was recently found that, the high flux of neutrinos at $\sim30$ TeV detected by IceCube lead to a cumulative gamma-ray flux exceeding the Fermi isotropic gamma-ray background at 10-100 GeV, implying that the neutrinos are produced by hidden sources of cosmic rays, where GeV-TeV gamma-rays are not transparent. Here we suggest that relativistic jets in tidal disruption events (TDEs) of supermassive black holes are such hidden sources. We consider the jet propagation in an extended,optically thick envelope around the black hole, which is resulted from the ejected material during the disruption. While powerful jets can break free from the envelope, less powerful jets would be choked inside the envelope. The jets accelerate cosmic rays through internal shocks or reverse shocks and further produce neutrinos via interaction with the surrounding dense medium or photons. All three TDE jets discovered so far are not detected by Fermi/LAT, suggesting that GeV-TeV gamma-rays are absorbed in these jets. The cumulative neutrino flux from TDE jets can account for the neutrino flux observed by IceCube at PeV energies and may also account for the higher flux at $\sim30$ TeV if less powerful, choked jets are present in the majority of TDEs.
Noise-cancellation algorithm for simulations of Brownian particles
Creators: name: Rusch, Regina
name: Franosch, Thomas
name: Jung, Gerhard
Publisher: name: arXiv
Year: 2024
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We investigate the usage of a recently introduced noise-cancellation algorithm for Brownian simulations to enhance the precision of measuring transport properties such as the mean-square displacement or the velocity-autocorrelation function. The algorithm is based on explicitly storing the pseudo-random numbers used to create the randomized displacements in computer simulations and subtracting them from the simulated trajectories. The resulting correlation function of the reduced motion is connected to the target correlation function up to a cross-correlation term. Using analytical theory and computer simulations, we demonstrate that the cross-correlation term can be neglected in all three systems studied in this aper. We further expand the algorithm to Monte Carlo simulations and analyze the performance of the algorithm and rationalize that it works particularly well for unbounded, weakly interacting systems in which the precision of the mean-square displacement can be improved by orders of magnitude.
description: 10 pages, 9 figures
Transition in steady streaming and pumping caused by a sphere oscillating in a viscous incompressible fluid
Creators: name: Felderhof, B. U.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: The steady streaming flow pattern caused by a no-slip sphere oscillating in an unbounded viscous incompressible fluid is calculated exactly to second order in the amplitude. The pattern depends on a dimensionless scale number, determined by sphere radius, frequency of oscillation, and kinematic viscosity of the fluid. At a particular value of the scale number there is a transition with a reversal of flow. The analytical solution of the flow equations is based on a set of antenna theorems. The flow pattern consists of a boundary layer and an adjacent far-field of long range, falling off with the inverse square distance from the center of the sphere. The boundary layer becomes thin in the limit where inertia dominates over viscosity. The system acts as a pump operating in two directions, depending on the scale number. The efficiency of the pump is estimated from a comparison of the rate of flow with the rate of dissipation.
description: 17 pages, 8 figures
Equilibration Properties of Classical Integrable Field Theories
Creators: name: De Luca, Andrea
name: Mussardo, Giuseppe
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We study the equilibration properties of classical integrable field theories at a finite energy density, with a time evolution that starts from initial conditions far from equilibrium. These classical field theories may be regarded as quantum field theories in the regime of high occupation numbers. This observation permits to recover the classical quantities from the quantum ones by taking a proper $\hbar \rightarrow 0$ limit. In particular, the time averages of the classical theories can be expressed in terms of a suitable version of the LeClair-Mussardo formula relative to the Generalized Gibbs Ensemble. For the purposes of handling time averages, our approach provides a solution of the problem of the {\em infinite gap solutions} of the Inverse Scattering Method.
description: 67 pages (+ 9 pages of appendices), 26 figures; review article for special issue of JSTAT on Quantum Integrability in Out of Equilibrium Systems; comments are welcome
Constraints on Self-Interacting dark matter from relaxed galaxy groups
Creators: name: K., Gopika
name: Desai, Shantanu
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Self-interacting dark matter (SIDM) has been proposed as an alternative to the standard collisionless cold dark matter to explain the diversity of galactic rotation curves and core-cusp problems seen at small scales. Here, we estimate the constraints on SIDM for a sample of 11 relaxed galaxy groups with X-ray observations from Chandra and XMM-Newton. We fit the dark matter density distribution to the Einasto profile and use the estimated Einasto $α$ parameter to constrain the SIDM cross-section, based on the empirical relation between the two, which was obtained in Eckert et al (2022). We obtain a non-zero central estimate for the cross-section per unit mass ($σ/m$) for seven groups, with the most precise estimate obtained for NGC 5044, given by $σ/m=0.165 \pm 0.025~\rm{cm^2/g}$, for dark matter velocity dispersion of about 300 km/sec. For the remaining four groups, we obtain 95% c.l. upper limits on $σ/m < 0.16-6.61~\rm{cm^2/g}$ with dark matter velocity dispersions between 200-500 km/sec, with the most stringent limit for our sample obtained for the group MKW 4, given by $σ/m< 0.16~\rm{cm^2/g}$ for dark matter velocity dispersion of about 350 km/sec.
description: 14 pages, 22 figures. Accepted in Phys. Dark Universe
An Alternative Formation Scenario for Uranium-rich Giants: Engulfing a Earth-like Planet
Creators: name: Xie, Dian
name: Zhu, Chunhua
name: Guo, Sufen
name: Liu, Helei
name: Lü, Guoliang
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The actinides, such as the uranium (U) element, are typically synthesized through the rapid neutron-capture process (r-process), which can occur in core-collapse supernovae or double neutron star mergers. There exist nine r-process giant stars exhibiting conspicuousUabundances, commonly referred to as U-rich giants. However, the origins of these U-rich giants remain ambiguous. We propose an alternative formation scenario for these U-rich giants whereby a red giant (RG) engulfs an Earth-like planet. To approximate the process of a RG engulfing an Earth-like planet, we employ an accretion model wherein the RG assimilates materials from said planet. Our findings demonstrate that this engulfment event can considerably enhance the presence of heavy elements originating from Earth-like planets on the surfaces of very metal-poor stars (Z = 0.00001), while its impact on solar-metallicity stars is comparatively modest. Importantly, the structural and evolutionary properties of both very metalpoor and solar-metallicity stars remain largely unaffected. Notably, our engulfment model effectively accounts for the observed U abundances in known U-rich giants. Furthermore, the evolutionary trajectories of U abundances on the surfaces of RGs subsequent to the engulfment of Earth-like planets encompass all known U-rich giants. Therefore, it is plausible that U-rich giants are formed when a RG engulfs an Earth-like planet.
description: 9 pages, 8 figures, accepted 2023 July 10 by MNRAS
Basalys euterpe Nixon 1980
Creators: name: Notton, David G.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Diapriidae
Basalys
Basalys euterpe

description: Basalys euterpe Nixon, 1980: 30.
Valid name
Basalys semele Nixon, 1980.
Summary of types
Holotype ♂, BMNH number 9.822, by original designation. Paratypes 4 ♂♂.
Primary type data
Co. Sligo / Trawallua/ 24- 29.7.1933 / G.Nixon; Basalys / euterpe/ Nixon/ type ♂, 197.
Type locality
Ireland, County Sligo, Trawallua.
Remarks
The holotype is mounted on a card point and is entire.
description: Published as part of Notton, David G., 2014, A catalogue of the types of Diapriinae (Hymenoptera, Diapriidae) at the Natural History Museum, London, pp. 1-123 in European Journal of Taxonomy 75 on page 99, DOI: 10.5852/ejt.2014.75, http://zenodo.org/record/3862773
Superconductivity enhancement in the S-doped Weyl semimetal candidate MoTe2
Creators: name: Chen, F. C.
name: Luo, X.
name: Xiao, R. C.
name: Lu, W. J.
name: Zhang, B.
name: Yang, H. X.
name: Li, J. Q.
name: Pei, Q. L.
name: Shao, D. F.
name: Zhang, R. R.
name: Ling, L. S.
name: Xi, C. Y.
name: Song, W. H.
name: Sun, Y. P.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Two-dimensional (2D) transition-metal dichalcogenide (TMDs) MoTe2 has attracted much attention due to its predicted Weyl semimetal (WSM) state and a quantum spin Hall insulator in bulk and monolayer form, respectively. We find that the superconductivity in MoTe2 single crystal can be much enhanced by the partial substitution of the Te ions by the S ones. The maximum of the superconducting temperature TC of MoTe1.8S0.2 single crystal is about 1.3 K. Compared with the parent MoTe2 single crystal (TC=0.1 K), nearly 13-fold in TC is improved in MoTe1.8S0.2 one. The superconductivity has been investigated by the resistivity and magnetization measurements. MoTe2-xSx single crystals belong to weak coupling superconductors and the improvement of the superconductivity may be related to the enhanced electron-phonon coupling induced by the S-ion substitution. A dome-shape superconducting phase diagram is obtained in the S-doped MoTe2 single crystals. MoTe2-xSx materials may provide a new platform for our understanding of superconductivity phenomena and topological physics in TMDs.
description: the "Author contributions" is updated
Searching for universality of dineutron correlation at the surface of Borromean nuclei
Creators: name: Corsi, A.
name: Kubota, Y.
name: Casal, J.
name: Gomez-Ramos, M.
name: Moro, A. M.
name: Authelet, G.
name: Baba, H.
name: Caesar, C.
name: Calvet, D.
name: Delbart, A.
name: Dozono, M.
name: Feng, J.
name: Flavigny, F.
name: Gheller, J. -M.
name: Gibelin, J.
name: Giganon, A.
name: Gillibert, A.
name: Hasegawa, K.
name: Isobe, T.
name: Kanaya, Y.
name: Kawakami, S.
name: Kim, D.
name: Kiyokawa, Y.
name: Kobayashi, M.
name: Kobayashi, N.
name: Kobayashi, T.
name: Kondo, Y.
name: Korkulu, Z.
name: Koyama, S.
name: Lapoux, V.
name: Maeda, Y.
name: Marqués, F. M.
name: Motobayashi, T.
name: Miyazaki, T.
name: Nakamura, T.
name: Nakatsuka, N.
name: Nishio, Y.
name: Obertelli, A.
name: Ohkura, A.
name: Orr, N. A.
name: Ota, S.
name: Otsu, H.
name: Ozaki, T.
name: Panin, V.
name: Paschalis, S.
name: Pollacco, E. C.
name: Reichert, S.
name: Rousse, J. -Y.
name: Saito, A. T.
name: Sakaguchi, S.
name: Sako, M.
name: Santamaria, C.
name: Sasano, M.
name: Sato, H.
name: Shikata, M.
name: Shimizu, Y.
name: Shindo, Y.
name: Stuhl, L.
name: Sumikama, T.
name: Sun, Y. L.
name: Tabata, M.
name: Togano, Y.
name: Tsubota, J.
name: Uesaka, T.
name: Yang, Z. H.
name: Yasuda, J.
name: Yoneda, K.
name: Zenihiro, J.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The dineutron correlation is systematically studied in three different Borromean nuclei near the neutron dripline, 11Li, 14Be and 17B, via the (p, pn) knockout reaction measured at the RIBF facility in RIKEN. For the three nuclei, the correlation angle between the valence neutrons is found to be largest in the same range of intrinsic momenta, which can be associated to the nuclear surface. This result reinforces the prediction that the formation of the dineutron is universal in environments with low neutron density, such as the surface of neutron-rich Borromean nuclei.
Toward Operationalizing Pipeline-aware ML Fairness: A Research Agenda for Developing Practical Guidelines and Tools
Creators: name: Black, Emily
name: Naidu, Rakshit
name: Ghani, Rayid
name: Rodolfa, Kit T.
name: Ho, Daniel E.
name: Heidari, Hoda
Publisher: name: arXiv
Year: 2023
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: While algorithmic fairness is a thriving area of research, in practice, mitigating issues of bias often gets reduced to enforcing an arbitrarily chosen fairness metric, either by enforcing fairness constraints during the optimization step, post-processing model outputs, or by manipulating the training data. Recent work has called on the ML community to take a more holistic approach to tackle fairness issues by systematically investigating the many design choices made through the ML pipeline, and identifying interventions that target the issue's root cause, as opposed to its symptoms. While we share the conviction that this pipeline-based approach is the most appropriate for combating algorithmic unfairness on the ground, we believe there are currently very few methods of \emph{operationalizing} this approach in practice. Drawing on our experience as educators and practitioners, we first demonstrate that without clear guidelines and toolkits, even individuals with specialized ML knowledge find it challenging to hypothesize how various design choices influence model behavior. We then consult the fair-ML literature to understand the progress to date toward operationalizing the pipeline-aware approach: we systematically collect and organize the prior work that attempts to detect, measure, and mitigate various sources of unfairness through the ML pipeline. We utilize this extensive categorization of previous contributions to sketch a research agenda for the community. We hope this work serves as the stepping stone toward a more comprehensive set of resources for ML researchers, practitioners, and students interested in exploring, designing, and testing pipeline-oriented approaches to algorithmic fairness.
description: EAAMO'23 (Archival)
Dynamics around the binary system (65803) Didymos
Creators: name: Oliveira, R. Machado
name: Winter, O. C.
name: Sfair, R.
name: Valvano, G.
name: Moura, T. S.
name: Borderes-Motta, G.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Didymos and Dimorphos are primary and secondary, respectively, asteroids who compose a binary system that make up the set of Near Earth Asteroids (NEAs). They are targets of the Double Asteroid Redirection Test (DART), the first test mission dedicated to study of planetary defense, for which the main goal is to measure the changes caused after the secondary body is hit by a kinect impactor. The present work intends to conduct a study, through numerical integrations, on the dynamics of massless particles distributed in the vicinity of the two bodies. An approximate shape for the primary body was considered as a model of mass concentrations (mascons) and the secondary was considered as a massive point. Our results show the location and size of stable regions, and also their lifetime.
Can the orbital distribution of Neptune's 3:2 mean motion resonance result from stability sculpting?
Creators: name: Balaji, Sricharan
name: Zaveri, Nihaal
name: Hayashi, Nanae
name: Ruiz, Arcelia Hermosillo
name: Barnes, Jackson
name: Murray-Clay, Ruth
name: Volk, Kathryn
name: Gerhardt, Jake
name: Syed, Zain
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We explore a simplified model of the outcome of an early outer Solar System gravitational upheaval during which objects were captured into Neptune's 3:2 mean motion resonance via scattering rather than smooth planetary migration. We use N-body simulations containing the Sun, the four giant planets, and test particles in the 3:2 resonance to determine whether long-term stability sculpting over 4.5 Gyr can reproduce the observed 3:2 resonant population from an initially randomly scattered 3:2 population. After passing our simulated 3:2 resonant objects through a survey simulator, we find that the semimajor axis (a) and eccentricity (e) distributions are consistent with the observational data (assuming an absolute magnitude distribution constrained by prior studies), suggesting that these could be a result of stability sculpting. However, the inclination (i) distribution cannot be produced be stability sculpting and thus must result from a distinct process that excited the inclinations. Our simulations modestly under-predict the number of objects with high libration amplitudes (Aϕ), possibly because we do not model transient sticking. Finally, our model under-populates the Kozai subresonance compared to both observations and to smooth migration models. Future work is needed to determine whether smooth migration occurring as Neptune's eccentricity damped to its current value can resolve this discrepancy.
description: 15 pages, 13 figures
The toughness, elasticity, color, and consistency of cooperation
Creators: name: Holme, Petter
Publisher: name: arXiv
Year: 2023
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: This is a comment on a recent review article about reputation and reciprocity as mechanisms promoting cooperation. I also discuss the necessary changes for the currently game-theory-based cooperation studies to become a complete theory of cooperation in our contemporary society.
Circulation in turbulent flow through a contraction
Creators: name: Mugundhan, Vivek
name: Thoroddsen, Sigurdur T.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We study experimentally the statistical properties and evolution of circulation in a turbulent flow passing through a smooth 2-D contraction. The turbulence is generated with an active grids to reach $Re_λ \simeq 220$ at the inlet to the 2.5:1 contraction. We employ time-resolved 3-D Lagrangian Particle Tracking technique with the Shake-The-Box algorithm to obtain volumetric velocity fields which we use to calculate the simultaneous circulation in three perpendicular planes. Forming a circulation vector and studying the PDFs of the relative strength of its components, we can quantify how the mean strain enhances and orients coherent vortical structures with the streamwise direction. This is further studied with streamwise space and time correlations of the circulations over a range of loop sizes. The streamwise component of the circulation, over same-size square loops, shows increased integral length, while the other two components are less affected. The circulation around the compressive direction weakens and reaches prominent negative correlation values, suggesting buckling or sharp reorientation of transverse vortices. The PDFs of circulation transit from non-Gaussian to Gaussian behavior as the loop size is increased from dissipative to large scales.
Giant Plasmon Instability in Dual-Grating-Gate Graphene Field-Effect Transistor
Creators: name: Koseki, Y.
name: Ryzhii, V.
name: Otsuji, T.
name: Popov, V. V.
name: Satou, A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We study instability of plasmons in a dual-grating-gate graphene field-effect transistor induced by dc current injection using self-consistent simulations with the Boltzmann equation. With only the acoustic-phonon-limited electron scattering, it is demonstrated that a total growth rate of the plasmon instability, with the terahertz/mid-infrared range of the frequency, can exceed $4\times10^{12}$ s$^{-1}$ at room temperature, which is an order of magnitude larger than in two-dimensional electron gases based on usual semiconductors. By Comparing the simulation results with existing theory, it is revealed that the giant total growth rate originates from simulataneous occurence of the so-called Dyakonov-Shur and Ryzhii-Satou-Shur instabilities.
description: 5 pages, 5 figures