cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Unveiling the formation of the massive DR21 ridge
Creators: name: Bonne, L.
name: Bontemps, S.
name: Schneider, N.
name: Simon, R.
name: Clarke, S. D.
name: Csengeri, T.
name: Chambers, E.
name: Graf, U.
name: Jackson, J. M.
name: Klein, R.
name: Okada, Y.
name: Tielens, A. G. G. M.
name: Tiwari, M.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present new $^{13}$CO(1-0), C$^{18}$O(1-0), HCO$^{+}$(1-0) and H$^{13}$CO$^{+}$(1-0) maps from the IRAM 30m telescope, and a spectrally-resolved [CII] 158 $μ$m map observed with the SOFIA telescope towards the massive DR21 cloud. This traces the kinematics from low- to high-density gas in the cloud which allows to constrain the formation scenario of the high-mass star forming DR21 ridge. The molecular line data reveals that the sub-filaments are systematically redshifted relative to the dense ridge. We demonstrate that [CII] unveils the surrounding CO-poor gas of the dense filaments in the DR21 cloud. We also show that this surrounding gas is organized in a flattened cloud with curved redshifted dynamics perpendicular to the ridge. The sub-filaments thus form in this curved and flattened mass reservoir. A virial analysis of the different lines indicates that self-gravity should drive the evolution of the ridge and surrounding cloud. Combining all results we propose that bending of the magnetic field, due to the interaction with a mostly atomic colliding cloud, explains the velocity field and resulting mass accretion on the ridge. This is remarkably similar to what was found for at least two nearby low-mass filaments. We tentatively propose that this scenario might be a widespread mechanism to initiate star formation in the Milky Way. However, in contrast to low-mass clouds, gravitational collapse plays a role on the pc scale of the DR21 ridge because of the higher density. This allows more effective mass collection at the centers of collapse and should facilitate massive cluster formation.
description: 32 pages, 28 figures, accepted in ApJ
A Class of logarithmically completely monotonic functions relating the $q$-gamma function and applications
Creators: name: Mehrez, Khaled
Publisher: name: arXiv
Year: 2015
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics

description: In this paper, the logarithmically complete monotonicity property for a functions involving $q$-gamma function is investigated for $q\in(0,1).$ As applications of this results, some new inequalities for the $q$-gamma function are established. Furthermore, let the sequence $r_n$ be defined by $$n!=\sqrt{2πn}(n/e)^n e^{r_n}.$$ We establish new estimates for Stirling's formula remainder $r_n.$
Joint Participation Incentive and Network Pricing Design for Federated Learning
Creators: name: Ding, Ningning
name: Gao, Lin
name: Huang, Jianwei
Publisher: name: arXiv
Year: 2023
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Computer Science and Game Theory (cs.GT)
subject: FOS: Computer and information sciences

description: Federated learning protects users' data privacy through sharing users' local model parameters (instead of raw data) with a server. However, when massive users train a large machine learning model through federated learning, the dynamically varying and often heavy communication overhead can put significant pressure on the network operator. The operator may choose to dynamically change the network prices in response, which will eventually affect the payoffs of the server and users. This paper considers the under-explored yet important issue of the joint design of participation incentives (for encouraging users' contribution to federated learning) and network pricing (for managing network resources). Due to heterogeneous users' private information and multi-dimensional decisions, the optimization problems in Stage I of multi-stage games are non-convex. Nevertheless, we are able to analytically derive the corresponding optimal contract and pricing mechanism through proper transformations of constraints, variables, and functions, under both vertical and horizontal interaction structures of the participants. We show that the vertical structure is better than the horizontal one, as it avoids the interests misalignment between the server and the network operator. Numerical results based on real-world datasets show that our proposed mechanisms decrease server's cost by up to 24.87% comparing with the state-of-the-art benchmarks.
Stable Generalized Finite Element Method and associated iterative schemes; application to interface problems
Creators: name: Kergrene, Kenan
name: Babuška, Ivo
name: Banerjee, Uday
Publisher: name: arXiv
Year: 2016
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: The Generalized Finite Element Method (GFEM) is an extension of the Finite Element Method (FEM), where the standard finite element space is augmented with a space of non-polynomial functions, called the enrichment space. The functions in the enrichment space mimic the local behavior of the unknown solution of the underlying variational problem. GFEM has been successfully applied to a wide range of problems. However, it often suffers from bad conditioning, i.e., its conditioning may not be robust with respect to the mesh and in fact, the conditioning could be much worse than that of the standard FEM. In this paper, we present a numerical study that shows that if the "angle" between the finite element space and the enrichment space is bounded away from 0, uniformly with respect to the mesh, then the GFEM is stable, i.e., the conditioning of GFEM is not worse than that of the standard FEM. A GFEM with this property is called a Stable GFEM (SGFEM). The last part of the paper is devoted to the derivation of a robust iterative solver exploiting this angle condition. It is shown that the required "wall-clock" time is greatly reduced compared to popular GFEMs used in the literature.
From quantum electrodynamics to a geometric gauge theory of classical electromagnetism
Creators: name: Marsh, Adam
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Physics (physics.gen-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences
subject: 81T13 (primary), 70S15, 70S20, 53C07, 53Z05 (Secondary)

description: A relativistic version of the correspondence principle, a limit in which classical electrodynamics may be derived from QED, has never been clear, especially when including gravitational mass. Here we introduce a novel classical field theory formulation of electromagnetism, and then show that it approximates QED in the limit of a quantum state which corresponds to a classical charged continua. Our formulation of electromagnetism features a Lagrangian which is gauge invariant, includes a classical complex field from which a divergenceless four-current may be derived, and reproduces all aspects of the classical theory of charged massive continua without any quantum effects. Taking a geometric approach, we identify the four-current as being in the direction of extremal phase velocity of the classical field; the field equations of motion determine this phase velocity as being equal to the mass, which makes the rest density proportional to the squared modulus of the field.
description: 33 pages, 6 figures; to appear in Int. J. Geom. Meth. Mod. Phys
Gas Kinematics and Star Formation in the Filamentary IRDC G34.43+0.24
Creators: name: Xu, Jin-Long
name: Li, Di
name: Zhang, Chuan-Peng
name: Liu, Xiao-Lan
name: Wang, Jun-Jie
name: Ning, Chang-Chun
name: Ju, Bing-Gang
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We performed a multiwavelength study toward infrared dark cloud (IRDC) G34.43+0.24. New maps of 13CO $J$=1-0 and C18}O J=1-0 were obtained from the Purple Mountain Observatory (PMO) 13.7 m radio telescope. At 8 um (Spitzer - IRAC), IRDC G34.43+0.24 appears to be a dark filament extended by 18 arcmin along the north-south direction. Based on the association with the 870 um and C18O J=1-0 emission, we suggest that IRDC G34.43+0.24 should not be 18 arcmin in length, but extend by 34 arcmin. IRDC G34.43+0.24 contains some massive protostars, UC H II regions, and infrared bubbles. The spatial extend of IRDC G34.43+0.24 is about 37 pc assuming a distance of 3.7 kpc. IRDC G34.43+0.24 has a linear mass density of 1.6*10^{3} M_{sun} pc^{-1}, which is roughly consistent with its critical mass to length ratio. The turbulent motion may help stabilizing the filament against the radial collapse. Both infrared bubbles N61 and N62 show a ringlike structure at 8 um. Particularly, N61 has a double-shell structure, which has expanded into IRDC G34.43+0.24. The outer shell is traced by 8 um and 13}CO J=1-0 emission, while the inner shell is traced by 24 um and 20 cm emission. We suggest that the outer shell (9.9*10^{5} yr) is created by the expansion of H II region G34.172+0.175, while the inner shell (4.1-6.3*10^{5} yr) may be produced by the energetic stellar wind of its central massive star. From GLIMPSE I catalog, we selected some Class I sources with an age of 10^{5} yr. These Class I sources are clustered along the filamentary molecular cloud.
description: 44 pages, 13 figures, accepted for publication in ApJ
Mobile Journalism Practice in the Kompas.com Newsroom
Creators: name: Prestianta, Albertus
Publisher: name: figshare
Year: 2023
Subjects: Professional writing and journalism practice
Journalism studies
Media studies
Communication technology and digital media studies

description: Smartphones and social media have changed how the media gather, produce, edit, and disseminate news. By employing the journalistic capital concept, this paper examines how journalists in Kompas.com, one of the pioneers of online media in Indonesia, incorporate mobile journalism practice into their work. This article explores how journalists and newsrooms respond to change that coincides with mobile devices and social media in the newsroom. The qualitative data analysis obtained from in-depth interviews with Kompas.com journalists and document analysis revealed that the application of mojo in Kompas.com is relatively new and is still looking for a form. Kompas.com integrate mobile smartphones into journalistic work to produce stories with a multimedia approach to meet changing journalistic and business needs. Journalists are expected to produce journalistic content in short videos using mobile devices related to daily events around them. Thus, the practice of mojo emerged as a new order in journalism. Kompas.com develops a multimedia division and improves journalists’ skills through training on all desks in the newsroom. Journalists learn new applications and tools and produce short videos for social media.
Colloquium: Quantum and Classical Discrete Time Crystals
Creators: name: Zaletel, Michael P.
name: Lukin, Mikhail
name: Monroe, Christopher
name: Nayak, Chetan
name: Wilczek, Frank
name: Yao, Norman Y.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Quantum Gases (cond-mat.quant-gas)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Cellular Automata and Lattice Gases (nlin.CG)
subject: FOS: Physical sciences

description: The spontaneous breaking of time translation symmetry has led to the discovery of a new phase of matter - the discrete time crystal. Discrete time crystals exhibit rigid subharmonic oscillations, which result from a combination of many-body interactions, collective synchronization, and ergodicity breaking. This Colloquium reviews recent theoretical and experimental advances in the study of quantum and classical discrete time crystals. We focus on the breaking of ergodicity as the key to discrete time crystals and the delaying of ergodicity as the source of numerous phenomena that share many of the properties of discrete time crystals, including the AC Josephson effect, coupled map lattices, and Faraday waves. Theoretically, there exists a diverse array of strategies to stabilize time crystalline order in both closed and open systems, ranging from localization and prethermalization to dissipation and error correction. Experimentally, many-body quantum simulators provide a natural platform for investigating signatures of time crystalline order; recent work utilizing trapped ions, solid-state spin systems, and superconducting qubits will be reviewed. Finally, this Colloquium concludes by describing outstanding challenges in the field and a vision for new directions on both the experimental and theoretical fronts.
description: 29 pages, 13 figures; commissioned review for Reviews of Modern Physics
KP hierarchy for the cyclic quiver
Creators: name: Chalykh, Oleg
name: Silantyev, Alexey
Publisher: name: arXiv
Year: 2015
Subjects: subject: Quantum Algebra (math.QA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We introduce a generalisation of the KP hierarchy, closely related to the cyclic quiver and the Cherednik algebra $H_k(\mathbb Z_m)$. This hierarchy depends on $m$ parameters (one of which can be eliminated), with the usual KP hierarchy corresponding to the $m=1$ case. Generalising the result of G. Wilson, we show that our hierarchy admits solutions parameterised by suitable quiver varieties. The pole dynamics for these solutions is shown to be governed by the classical Calogero-Moser system for the wreath-product $\mathbb Z_m\wr S_n$ and its new spin version. These results are further extended to the case of the multi-component hierarchy.
description: 40 pages
A robust and efficient adaptive multigrid solver for the optimal control of phase field formulations of geometric evolution laws
Creators: name: Yang, F.
name: Venkataraman, C.
name: Styles, V.
name: Madzvamuse, A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: We propose and investigate a novel solution strategy to efficiently and accurately compute approximate solutions to semilinear optimal control problems, focusing on the optimal control of phase field formulations of geometric evolution laws. The optimal control of geometric evolution laws arises in a number of applications in fields including material science, image processing, tumour growth anda cell motility. In the current work we focus on a phase field formulation of the optimal control problem, hence exploiting the well developed mathematical theory for the optimal control of semilinear parabolic partial differential equations. Approximation of the resulting optimal control problem is computationally challenging, requiring massive amounts of computational time and memory storage. The main focus of this work is to propose, derive, implement and test an efficient solution method for such problems. The solver for the discretised partial differential equations is based upon a geometric multigrid method incorporating advanced techniques to deal with the nonlinearities in the problem and utilising adaptive mesh refinement. An in-house two-grid solution strategy for the forward and adjoint problems, that significantly reduces memory requirements and CPU time, is proposed and investigated computationally. Furthermore, parallelisation as well as an adaptivestep gradient update for the control are employed to further improve efficiency. Along with a detailed description of our proposed solution method together with its implementation we present a number of computational results that demonstrate and evaluate our algorithms with respect to accuracy and efficiency. A highlight of the present work is simulation results on the optimal control in 3-D which would be computationally infeasible without the solution strategies proposed in the present work.
description: 29 pages, 13 figures
Fraction of Clumpy Star-Forming Galaxies at $0.5\leq z\leq 3$ in UVCANDELS: Dependence on Stellar Mass and Environment
Creators: name: Sattari, Zahra
name: Mobasher, Bahram
name: Chartab, Nima
name: Kelson, Daniel D.
name: Teplitz, Harry I.
name: Rafelski, Marc
name: Grogin, Norman A.
name: Koekemoer, Anton M.
name: Wang, Xin
name: Windhorst, Rogier A.
name: Alavi, Anahita
name: Prichard, Laura
name: Sunnquist, Ben
name: Gardner, Jonathan P.
name: Gawiser, Eric
name: Hathi, Nimish P.
name: Hayes, Matthew J.
name: Ji, Zhiyuan
name: Mehta, Vihang
name: Robertson, Brant E.
name: Scarlata, Claudia
name: Yung, L. Y. Aaron
name: Conselice, Christopher J.
name: Dai, Y. Sophia
name: Guo, Yicheng
name: Lucas, Ray A.
name: Martin, Alec
name: Ravindranath, Swara
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: High-resolution imaging of galaxies in rest-frame UV has revealed the existence of giant star-forming clumps prevalent in high redshift galaxies. Studying these sub-structures provides important information about their formation and evolution and informs theoretical galaxy evolution models. We present a new method to identify clumps in galaxies' high-resolution rest-frame UV images. Using imaging data from CANDELS and UVCANDELS, we identify star-forming clumps in an HST/F160W$\leq 25$ AB mag sample of 6767 galaxies at $0.5\leq z\leq 3$ in four fields, GOODS-N, GOODS-S, EGS, and COSMOS. We use a low-pass band filter in Fourier space to reconstruct the background image of a galaxy and detect small-scale features (clumps) on the background-subtracted image. Clumpy galaxies are defined as those having at least one off-center clump that contributes a minimum of 10$\%$ of the galaxy's total rest-frame UV flux. We measure the fraction of clumpy galaxies ($\rm f_{clumpy}$) as a function of stellar mass, redshift, and galaxy environment. Our results indicate that $\rm f_{clumpy}$ increases with redshift, reaching $\sim 65\%$ at $z\sim 1.5$. We also find that $\rm f_{clumpy}$ in low-mass galaxies ($\rm 9.5\leq log(M_*/M_\odot)\leq 10$) is 10$\%$ higher compared to that of their high-mass counterparts ($\rm log(M_*/M_\odot)>10.5$). Moreover, we find no evidence of significant environmental dependence of $\rm f_{clumpy}$ for galaxies at the redshift range of this study. Our results suggest that the fragmentation of gas clouds under violent disk instability remains the primary driving mechanism for clump formation, and incidents common in dense environments, such as mergers, are not the dominant processes.
description: 16 pages, 11 figures, 2 tables, accepted for publication in ApJ
High precision measurement of the Dzyaloshinsky-Moriya interaction between two rare-earth ions in a solid
Creators: name: Laplane, Cyril
name: Cruzeiro, Emmanuel Zambrini
name: Fröwis, Florian
name: Goldner, Philippe
name: Afzelius, Mikael
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Other Condensed Matter (cond-mat.other)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We report on a direct measurement of the pair-wise anti-symmetric exchange interaction, known as the Dzyaloshinsky-Moriya interaction (DMI), in a Nd3+-doped YVO4 crystal. To this end we introduce a broadband electron spin resonance technique coupled with an optical detection scheme which selectively detects only one Nd3+-Nd3+ pair. Using this technique we can fully determine the spin-spin coupling tensor, allowing us to experimentally determine both the strength and direction of the DMI vector. We believe that this ability to fully determine the interaction Hamiltonian is of interest for studying the numerous magnetic phenomena where the DMI interaction is of fundamental importance, including multiferroics. We also detect a singlet-triplet transition within the pair, with a highly suppressed magnetic-field dependence, which suggests that such systems could form singlet-triplet qubits with long coherence times for quantum information applications.
All-graphene edge contacts: Electrical resistance of graphene T-junctions
Creators: name: Jacobsen, Kåre Wedel
name: Falkenberg, Jesper Toft
name: Papior, Nick
name: Bøggild, Peter
name: Jauho, Antti-Pekka
name: Brandbyge, Mads
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Using ab-initio methods we investigate the possibility of three-terminal graphene "T-junction" devices and show that these all-graphene edge contacts are energetically feasible when the 1D interface itself is free from foreign atoms. We examine the energetics of various junction structures as a function of the atomic scale geometry. Three-terminal equilibrium Green's functions are used to determine the transmission spectrum and contact resistance of the system. We find that the most symmetric structures have a significant binding energy, and we determine the contact resistances in the junction to be in the range of 1-10 kOhm which is comparable to the best contact resistance reported for edge-contacted graphene-metal contacts. We conclude that conducting all-carbon T-junctions should be feasible.
Ionized gas metallicity of the strong [OIII]λ emission-line compact galaxies in the LAMOST survey
Creators: name: Liu, Siqi
name: Luo, A-Li
name: Zhang, Wei
name: Kong, Xiao
name: Zhao, Yong-Heng
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: This article reports a sample of 1830 strong [O III] λ5007 emission-line compact galaxies discovered with the LAMOST spectroscopic survey and the photometric catalog of SDSS. We newly identify 402 spectra of 346 strong [O III]λ5007 emission-line compact galaxies by finding compact isolated point sources. Combined with the samples in our previous work (Liu et al. 2022), this returns a sample of 1830 unique strong [O III]λ5007 emission-line compact galaxies with 2033 spectra of z <= 0.53. For the sources with 2σ [OIII]λ4363 detections, we calculate the gas-phase metallicity with the direct-Te method, and verify that the strong-line metallicity diagnostics calibrated with the direct-Te method also applies to this sample. The strong [O III]λ5007 emission-line compact galaxies fall below several Te-calibrated mass-metallicity relations. The N/O measurements of the strong [O iii]λ5007 emission-line compact galaxies mainly locate at a plateau at low metallicity, indicating the product of primary nucleosynthesis. The Ne3O2 and O32 relation follows a tight linear relation with no redshift evolution. The Ne3O2 anti-correlates with the stellar mass, and at fixed stellar mass the Ne3O2 increase with the redshift. Eight sources with asymmetric [O III]λ5007 emission-line profiles have been identified, however with no [O III]λ4363 detection, which proves the rich metal content and complex ionized gas kinematics within the galaxies. Higher-resolution spectroscopy will be necessary to identify the ionized gas components in detail.
description: 20 pages, 13 pictures, accepted by ApJS
Completely exceptional $2^\textrm{nd}$ order PDEs via conformal geometry and BGG resolution
Creators: name: Gutt, Jan
name: Manno, Gianni
name: Moreno, Giovanni
Publisher: name: arXiv
Year: 2016
Subjects: subject: Differential Geometry (math.DG)
subject: Mathematical Physics (math-ph)
subject: Analysis of PDEs (math.AP)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 30, 80

description: By studying the development of shock waves out of discontinuity waves, in 1954 P. Lax discovered a class of PDEs, which he called 'completely exceptional', where such a transition does not occur after a finite time. A straightforward integration of the completely exceptionality conditions allowed Boillat to show that such PDEs are actually of Monge-Ampere type. In this paper, we first recast these conditions in terms of characteristics, and then we show that the completely exceptional PDEs, with 2 or 3 independent variables, can be described in terms of the conformal geometry of the Lagrangian Grassmannian, where they are naturally embedded. Moreover, for an arbitrary number of independent variables, we show that the space of r-th degree sections of the Lagrangian Grassmannian can be resolved via a BGG operator. In the particular case of 1st degree sections, i.e., hyperplane sections or, equivalently, Monge-Ampere equations, such operator is a close analog of the trace-free second fundamental form.
description: 21 pages, 2 figures, accepted on Journal of Geometry and Physics
On the redshift evolution of the baryon and gas fraction in simulated groups and clusters of galaxies
Creators: name: Angelinelli, M.
name: Ettori, S.
name: Dolag, K.
name: Vazza, F.
name: Ragagnin, A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We study the redshift evolution of the baryon budget in a large set of galaxy clusters from the {\it Magneticum} suite of SPH cosmological simulations. At high redshifts, we obtain "closed box" systems independently by the mass of the systems on radii greater than $3R_{500,\mathrm c}$, whereas at lower redshifts, only the most massive halos could be considered as `"closed box". The baryon fraction shows a general decrease with the redshift and, for less massive objects, we observe a much more prominent decrease than for massive halos. The gas depletion parameter $Y_{\rm gas}$ shows a steeper and highly scattered radial distribution in the central regions of less massive halos with respect to massive objects at all redshifts, while on larger radii the gas fraction distributions are independent of the masses or the redshifts. The hot component of the gas traces well the total amount of gas at low redshifts. At higher redshifts, the cold component provides a not negligible contribution to the total amount of baryon in our systems. Moreover, the behaviour of the baryonic, entire gas, and hot gas phase depletion parameters as a function of radius, mass, and redshift are described by some functional forms. The evolution of metallicity and stellar mass in halos suggests that the early enrichment process is dominant. We investigate correlations between the time evolution of AGN feedback and the depletion parameters. We demonstrate that the energy injected by the AGN activity shows a particularly strong positive correlation with $Y_{\rm bar}$, $Y_{\rm cold}$,$Y_{\rm star}$ and a negative one with $Y_{\rm hot}$, $Z_{\rm Tot}$. These trends are consistent with previous works, meaning that our results, combined with findings derived from current and future X-rays observations, represent possible proxies to test the AGN feedback models used in different suites of numerical simulations.
description: Accepted in A&A, 15 pages, 11 figures
How else can we detect Fast Radio Bursts?
Creators: name: Lyutikov, Maxim
name: Lorimer, Duncan R.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We discuss possible electromagnetic signals accompanying Fast Radio Bursts (FRBs) that are expected in the scenario where FRBs originate in neutron star magnetospheres. For models involving Crab-like giant pulses, no appreciable contemporaneous emission is expected at other wavelengths. Magnetar giant flares, driven by the reconfiguration of the magnetosphere, however, can produce both contemporaneous bursts at other wavelengths as well as afterglow-like emission. We conclude that the best chances are: (i) prompt short GRB-like emission; (ii) a contemporaneous optical flash that can reach naked eye peak luminosity (but only for a few milliseconds); (iii) a high energy afterglow emission. Case (i) could be tested by coordinated radio and high-energy experiments. Case (ii) could be seen in a coordinated radio-optical surveys, \eg\ by the Palomar Transient Factory in a 60-second frame as a transient object of $m=15-20$ magnitude with an expected optical detection rate of about 0.1~hr$^{-1}$, an order of magnitude higher than in radio. Shallow, but large-area sky surveys such as ASAS-SN and EVRYSCOPE could also detect prompt optical flashes from the more powerful Lorimer-burst clones. The best constraints on the optical-to-radio power for this kind of emission could be provided by future observations with facilities like LSST. Case (iii) might be seen in relatively rare cases that the relativistically ejected magnetic blob is moving along the line of sight.
Consistent quantization of massless fields of any spin and the generalized Maxwell's equations
Creators: name: Gersten, Alexander
name: Moalem, Amnon
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: A simplified formalism of first quantized massless fields of any spin is presented. The angular momentum basis for particles of zero mass and finite spin s of the D^(s-1/2,1/2) representation of the Lorentz group is used to describe the wavefunctions. The advantage of the formalism is that by equating to zero the s-1 components of the wave functions, the 2s-1 subsidiary conditions (needed to eliminate the non-forward and non-backward helicities) are automatically satisfied. Probability currents and Lagrangians are derived allowing a first quantized formalism. A simple procedure is derived for connecting the wave functions with potentials and gauge conditions. The spin 1 case is of particular interest and is described with the D^(1/2,1/2) vector representation of the well known self-dual representation of the Maxwell's equations. This representation allows us to generalize Maxwell's equations by adding the E_0 and B_0 components to the electric and magnetic four-vectors. Restrictions on their existence are discussed.
description: IARD 2014
Deep learning in bifurcations of particle trajectories
Creators: name: Mohseni, Morteza
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: FOS: Physical sciences

description: We show that deep learning algorithms can be deployed to study bifurcations of particle trajectories. We demonstrate this for two physical systems, the unperturbed Duffing equation and charged particles in magnetic reversal by using the AI Poincaré algorithm. We solve the equations of motion by using a fourth-order Runge-Kutta method to generate a dataset for each system. We use a deep neural network to train the data. A noise characterized by a noise scale L is added to data during the training. By using a principal component analysis, we compute the explained variance ratios for these systems which depend on the noise scale. By plotting explained ratios against the noise scale, we show that they change at bifurcations. For different values of the Duffing equation parameters, these changes are of the form of different patterns of growth-decline of the explained ratios. For the magnetic reversal, the changes are of the form of a change in the number of principal components. We comment on the use of this technique for other dynamical systems with bifurcations.
Stokesian swimming of a prolate spheroid at low Reynolds number
Creators: name: Felderhof, B. U.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: The swimming of a spheroid immersed in a viscous fluid and performing surface deformations periodically in time is studied on the basis of Stokes equations of low Reynolds number hydrodynamics. The average over a period of time of the swimming velocity and the rate of dissipation are given by integral expressions of second order in the amplitude of surface deformations. The first order flow velocity and pressure, as functions of spheroidal coordinates, are expressed as sums of basic solutions of Stokes equations. Sets of superposition coefficients of these solutions which optimize the mean swimming speed for given power are derived from an eigenvalue problem. The maximum eigenvalue is a measure of the efficiency of the optimal stroke within the chosen class of motions. The maximum eigenvalue for sets of low order is found to be a strongly increasing function of the aspect ratio of the spheroid.
description: 17 pages, 5 figures. arXiv admin note: text overlap with arXiv:1602.01249
Asymptotic relation for the transition density of the three-dimensional Markov random flight on small time intervals
Creators: name: Kolesnik, Alexander D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60K35, 60K99, 60J60, 60J65, 82C41, 82C70

description: We consider the Markov random flight $\bold X(t), \; t>0,$ in the three-dimensional Euclidean space $\Bbb R^3$ with constant finite speed $c>0$ and the uniform choice of the initial and each new direction at random time instants that form a homogeneous Poisson flow of rate $λ>0$. Series representations for the conditional characteristic functions of $\bold X(t)$ corresponding to two and three changes of direction, are obtained. Based on these results, an asymptotic formula, as $t\to 0$, for the unconditional characteristic function of $\bold X(t)$ is derived. By inverting it, we obtain an asymptotic relation for the transition density of the process. We show that the error in this formula has the order $o(t^3)$ and, therefore, it gives a good approximation on small time intervals whose lengths depend on $λ$. Estimate of the accuracy of the approximation is analysed.
description: 19 pages, 5 figures
Entomacis penelope Nixon 1980
Creators: name: Notton, David G.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Diapriidae
Entomacis
Entomacis penelope

description: Entomacis penelope Nixon, 1980: 12.
Valid name
Entomacis penelope Nixon, 1980.
Summary of types
Holotype ♀, BMNH number 9.809, by original designation.
Primary type data
Eire / Co. Sligo / Bundoran/ vii.1933 / G.E.J.Nixon; Entomacis / penelope/ Nixon/ type ♀, 197.
Type locality
Ireland, County Sligo, Bundoran.
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 94, DOI: 10.5852/ejt.2014.75, http://zenodo.org/record/3862773
High Throughput Training of Deep Surrogates from Large Ensemble Runs
Creators: name: Meyer, Lucas
name: Schouler, Marc
name: Caulk, Robert Alexander
name: Ribés, Alejandro
name: Raffin, Bruno
Publisher: name: arXiv
Year: 2023
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: FOS: Computer and information sciences

description: Recent years have seen a surge in deep learning approaches to accelerate numerical solvers, which provide faithful but computationally intensive simulations of the physical world. These deep surrogates are generally trained in a supervised manner from limited amounts of data slowly generated by the same solver they intend to accelerate. We propose an open-source framework that enables the online training of these models from a large ensemble run of simulations. It leverages multiple levels of parallelism to generate rich datasets. The framework avoids I/O bottlenecks and storage issues by directly streaming the generated data. A training reservoir mitigates the inherent bias of streaming while maximizing GPU throughput. Experiment on training a fully connected network as a surrogate for the heat equation shows the proposed approach enables training on 8TB of data in 2 hours with an accuracy improved by 47% and a batch throughput multiplied by 13 compared to a traditional offline procedure.
description: The International Conference for High Performance Computing, Networking, Storage, and Analysis, Nov 2023, Denver, CO, United States
Phase Transitions of Traveling Salesperson Problems solved with Linear Programming and Cutting Planes
Creators: name: Schawe, Hendrik
name: Hartmann, Alexander K.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Complexity (cs.CC)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: The Traveling Salesperson problem asks for the shortest cyclic tour visiting a set of cities given their pairwise distances and belongs to the NP-hard complexity class, which means that with all known algorithms in the worst case instances are not solveable in polynomial time, i.e., the problem is hard. Though that does not mean, that there are not subsets of the problem which are easy to solve. To examine numerically transitions from an easy to a hard phase, a random ensemble of cities in the Euclidean plane given a parameter σ, which governs the hardness, is introduced. Here, a linear programming approach together with suitable cutting planes is applied. Such algorithms operate outside the space of feasible solutions and are often used in practical application but rarely studied in physics so far. We observe several transitions. To characterize these transitions, scaling assumptions from continuous phase transitions are applied
description: 4 pages, 6 figures
Using deep images and simulations to trace collisional debris around massive galaxies
Creators: name: Duc, Pierre-Alain
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Deep imaging programs, such as MATLAS which has just been completed at the CFHT, allows us to study with their diffuse light the outer stellar populations around large number of galaxies. We have carried out a systematic census of their fine structures, i.e. the collisional debris from past mergers. We have identified among them stellar streams from minor mergers, tidal tails from gas-rich major mergers, plumes from gas-poor major mergers, and shells from intermediate mass mergers. Having estimated the visibility and life time of each of these structures with numerical simulations, we can reconstruct the past mass assembly of the host galaxy. Preliminary statistical results based on a sample of 360 massive nearby galaxies are presented.
description: 3 pages, 2 figures, proceedings of IAU Symposium 321, "Formation and evolution of galaxy outskirts"
ALMA and Keck analysis of Fomalhaut field sources: JWST's Great Dust Cloud is a background object
Creators: name: Kennedy, Grant M.
name: Lovell, Joshua B.
name: Kalas, Paul
name: Fitzgerald, Michael P.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: At 7.7 pc, the A-type star Fomalhaut hosts a bright debris disk with multiple radial components. The disk is eccentric and misaligned, strongly suggesting that it is sculpted by interaction with one or more planets. Compact sources are now being detected with JWST, suggesting that new planet detections may be imminent. However, to confirm such sources as companions, common proper motion with the star must be established, as with unprecedented sensitivity comes a high probability that planet candidates are actually background objects. Here, ALMA and Keck observations of Fomalhaut are found to show significant emission at the same sky location as multiple compact sources in JWST MIRI coronagraphic observations, one of which has been dubbed the "Great Dust Cloud" because it lies within the outer belt. Since the ground-based data were obtained between 6 to 18 years prior to the JWST observations, these compact sources are unlikely to be common proper motion companions to Fomalhaut. More generally, this work illustrates that images collected at a range of wavelengths can be valuable for rejecting planet candidates uncovered via direct imaging with JWST.
description: MNRAS in press
Probabilistic tensor optimization of quantum circuits for the max-$k$-cut problem
Creators: name: Paradezhenko, G. V.
name: Pervishko, A. A.
name: Yudin, D.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We propose a technique for optimizing parameterized circuits in variational quantum algorithms based on the probabilistic tensor sampling optimization. This method allows one to relax random initialization issues or heuristics for generating initial guess of variational parameters, and can be used to avoid local minima. We illustrate our approach on the example of the quantum approximate optimization algorithm (QAOA) applied to the max-$k$-cut problem based on the binary encoding efficient in the number of qubits. We discuss the advantages of our technique for searching optimal variational parameters of QAOA circuits in comparison to classical optimization methods.
description: 8 pages, 5 figures
Searching for Intragroup Light in Deep U-band Imaging of the COSMOS Field
Creators: name: McCabe, Tyler
name: Redshaw, Caleb
name: Otteson, Lillian
name: Windhorst, Rogier A.
name: Jansen, Rolf A.
name: Cohen, Seth H.
name: Carleton, Timothy
name: Borthakur, Sanchayeeta
name: Ashcraft, Teresa A.
name: Koekemoer, Anton M.
name: Ryan, Russell E.
name: Nonino, Mario
name: Paris, Diego
name: Grazian, Andrea
name: Fontana, Andriano
name: Giallongo, Emanuele
name: Speziali, Roberto
name: Testa, Vincenzo
name: Boutsia, Konstantina
name: O'Connell, Robert W.
name: Rutkowski, Michael J.
name: Scarlata, Claudia
name: Teplitz, Harry I.
name: Wang, Xin
name: Rafelski, Marc
name: Grogin, Norman A.
name: Lucas, Ray A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the results of deep, ground based U-band imaging with the Large Binocular Telescope of the Cosmic Evolution Survey (COSMOS) field as part of the near-UV imaging program, UVCANDELS. We utilize a seeing sorted stacking method along with night-to-night relative transparency corrections to create optimal depth and optimal resolution mosaics in the U-band, which are capable of reaching point source magnitudes of AB 26.5 mag at 3 sigma. These ground based mosaics bridge the wavelength gap between the HST WFC3 F27W and ACS F435W images and are necessary to understand galaxy assembly in the last 9-10 Gyr. We use the depth of these mosaics to search for the presence of U-band intragroup light (IGrL) beyond the local Universe. Regardless of how groups are scaled and stacked, we do not detect any U-band IGrL to unprecedented U-band depths of 29.1-29.6 mag/arcsec2, which corresponds to an IGrL fraction of less than 1% of the total group light. This stringent upper limit suggests that IGrL does not contribute significantly to the Extragalactic Background Light at short wavelengths. Furthermore, the lack of UV IGrL observed in these stacks suggests that the atomic gas observed in the intragroup medium (IGrM) is likely not dense enough to trigger star formation on large scales. Future studies may detect IGrL by creating similar stacks at longer wavelengths or by pre-selecting groups which are older and/or more dynamically evolved similar to past IGrL observations of compact groups and loose groups with signs of gravitational interactions.
description: Accepted to PASP
Proceedings 7th International Workshop on Formal Methods and Analysis in Software Product Line Engineering
Creators: name: Rubin, Julia
name: Thüm, Thomas
Publisher: name: arXiv
Year: 2016
Subjects: subject: Software Engineering (cs.SE)
subject: Formal Languages and Automata Theory (cs.FL)
subject: FOS: Computer and information sciences

description: In Software Product Line Engineering (SPLE), a portfolio of similar systems is developed from a shared set of software assets. Claimed benefits of SPLE include reductions in the portfolio size, cost of software development and time to production, as well as improvements in the quality of the delivered systems. Yet, despite these benefits, SPLE is still in the early adoption stage. We believe that automated approaches, tools and techniques that provide better support for SPLE activities can further facilitate its adoption in practice and increase its benefits. To promote work in this area, the FMSPLE'16 workshop focuses on automated analysis and formal methods, which can (1) lead to a further increase in development productivity and reduction in maintenance costs associated with management of the SPLE artifacts, and (2) provide proven guarantees for the correctness and quality of the delivered systems.
Numerical analyses of wire-plate electrohydrodynamic flows
Creators: name: He, Xuerao
name: Vázquez, Pedro A.
name: Zhang, Mengqi
Publisher: name: arXiv
Year: 2023
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We present numerical analyses of 2-D electrohydrodynamic (EHD) flows of a dielectric liquid between a wire electrode and two plate electrodes with a Poiseuille flow, using direct numerical simulation and global stability analysis. Both conduction and injection mechanisms for charge generation are considered. In this work, we focused on the intensity of the cross-flow and studied the EHD flows without a cross-flow, with a weak cross-flow and with a strong cross-flow. (1)In the case without a cross-flow, we investigated its nonlinear flow structures and linear dynamics. We found that the flow in the conduction regime is steady, whereas the flow in the injection regime is oscillatory, which can be explained by a global stability analysis. (2)The EHD flow with a weak cross-flow is closely related to the flow phenomena in electrostatic precipitator (ESP). Our analyses indicate that increasing the cross-flow intensity or the electric Reynolds number leads to a less stable flow. Based on these results, we infer that one should adopt a relatively low voltage and weak cross-flow in the wire-plate EHD flow to avoid flow instability, which may hold practical implications for ESP. (3)The case of strong cross-flow is examined to study the EHD effect on the wake flow. By comparing the conventional cylindrical wake with the EHD wake in linear and nonlinear regimes, we found that the EHD effect brings forward the vortex shedding in wake flows. Besides, the EHD effect reduces the drag coefficient when the cross-flow is weak, but increases it when it is strong.
Atomically Engineered Electronic Two-Dimensional Organic Nanostructures
Creators: name: GOPALAKRISHNAN, DHANEESH KUMAR
Publisher: name: Monash University
Year: 2021
Subjects: Condensed matter physics not elsewhere classified

description: Present-day electronics—which form the bedrock of our modern technological advances—are quickly nearing fundamental limits of size and speed. Owing to their self-assembly capability, organic molecules can be engineered to form precise 2D (one-atom-thick) materials with novel quantum properties that can overcome those limits. This relies on the fundamental understanding of the physics and chemistry at the nanoscale, which is currently lacking. In this thesis, I further this understanding by studying the electronic properties of different 2D organic structures at the nanoscale. This work paves the way for the technological implementation of atomically engineered 2D organic materials with tailored properties for next-generation electronics.