cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The impact of spurious collisional heating on the morphological evolution of simulated galactic discs
Creators: name: Wilkinson, Matthew J.
name: Ludlow, Aaron D.
name: Lagos, Claudia del P.
name: Fall, S. Michael
name: Schaye, Joop
name: Obreschkow, Danail
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We use a suite of idealised N-body simulations to study the impact of spurious heating of star particles by dark matter particles on the kinematics and morphology of simulated galactic discs. We find that spurious collisional heating leads to a systematic increase of the azimuthal velocity dispersion ($σ_ϕ$) of stellar particles and a corresponding decrease in their mean azimuthal velocities ($\overline{v}_ϕ$). The rate of heating is dictated primarily by the number of dark matter halo particles (or equivalently, by the dark matter particle mass at fixed halo mass) and by radial gradients in the local dark matter density along the disc; it is largely insensitive to the stellar particle mass. Galaxies within haloes resolved with fewer than $\approx 10^6$ dark matter particles are particularly susceptible to spurious morphological evolution, irrespective of the total halo mass (with even more particles required to prevent heating of the galactic centre). Collisional heating transforms galactic discs from flattened structures into rounder spheroidal systems, causing them to lose rotational support in the process. It also affects the locations of galaxies in standard scaling relations that link their various properties: at fixed stellar mass, it increases the sizes of galaxies, and reduces their mean stellar rotation velocities and specific angular momenta. Our results urge caution when extrapolating simulated galaxy scaling relations to low masses where spurious collisional effects can bias their normalisation, slope and scatter.
description: Minor changes to match MNRAS published version. 20 pages, 13 figures
A new survey of cool supergiants in the Magellanic Clouds
Creators: name: González-Fernández, Carlos
name: Dorda, Ricardo
name: Negueruela, Ignacio
name: Marco, Amparo
Publisher: name: arXiv
Year: 2015
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: In this study, we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership to the clouds. Around two hundred new RSGs have been detected, hinting at a yet to be observed large population. Using near and mid infrared photometry we study the brightness distribution of these stars, the onset of mass-loss and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid and near infrared photometry to improve the observational efficiency of similar programs as this.
description: 39 pages, 10 figures. Accepted for publication in A&A
Krylov complexity of many-body localization: Operator localization in Krylov basis
Creators: name: Trigueros, Fabian Ballar
name: Lin, Cheng-Ju
Publisher: name: arXiv
Year: 2021
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study the operator growth problem and its complexity in the many-body localization (MBL) system from the Lanczos algorithm perspective. Using the Krylov basis, the operator growth problem can be viewed as a single-particle hopping problem on a semi-infinite chain with the hopping amplitudes given by the Lanczos coefficients. We find that, in the MBL systems, the Lanczos coefficients scale as $\sim n/\ln(n)$ asymptotically, same as in the ergodic systems, but with an additional even-odd alteration and an effective randomness. We use a simple linear extrapolation scheme as an attempt to extrapolate the Lanczos coefficients to the thermodynamic limit. With the original and extrapolated Lanczos coefficients, we study the properties of the emergent single-particle hopping problem via its spectral function, integrals of motion, Krylov complexity, wavefunction profile and return probability. Our numerical results of the above quantities suggest that the emergent single-particle hopping problem in the MBL system is localized when initialized on the first site. We also study the operator growth in the MBL phenomenological model, whose Lanczos coefficients also have an even-odd alteration, but approach constants asymptotically. The Krylov complexity grows linearly in time in this case.
description: 30 pages, 18 figures
Defining Millisecond Pulsars
Creators: name: Halder, Priyam
name: Goswami, Satyaki
name: Halder, Protyusha
name: Ghosh, Uday
name: Konar, Sushan
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Millisecond pulsars (MSP) are an important subclass of rotation powered pulsars (RPP), traditionally defined as those with $P_s < 20-30$~ms and $B_s \lesssim 10^{10}$~G. We re-examine this definition by applying Gaussian mixture model (GMM) analysis to identify distinct clusters within the RPP population and find that the MSPs appear to be better demarcated by the condition $\mathbf{P_s \lesssim 16}$~ms.
description: 3 pages, 1 figure
Bianchi's Hazzidakis transformation for generic higher dimensional quadrics
Creators: name: Dinca, Ion I.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics

description: We provide a generalization of Bianchi's Hazzidakis transformation from $2$-dimensional quadrics to generic higher dimensional quadrics.
description: arXiv admin note: substantial text overlap with arXiv:0808.2007; small correction in the last mentioning of \tilde z
Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions
Creators: name: Matute-Cañadas, F. J.
name: Metzger, C.
name: Park, Sunghun
name: Tosi, L.
name: Krogstrup, P.
name: Nygård, J.
name: Goffman, M. F.
name: Urbina, C.
name: Pothier, H.
name: Yeyati, A. Levy
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We performed microwave spectroscopy of an InAs nanowire between superconducting contacts implementing a finite-length, multi-channel Josephson weak link. Certain features in the spectra, such as the splitting by spin-orbit interactions of the transition lines among Andreev states, have been already understood in terms of non-interacting models. However, we identify here additional transitions, which evidence the presence of Coulomb interactions. By combining experimental measurements and model calculations, we reach a qualitative understanding of these very rich Andreev spectra.
description: (6+8) pages, (4+10) figures; added figure in SM
The fate of Parisi-Sourlas supersymmetry in Random Field models
Creators: name: Kaviraj, Apratim
name: Rychkov, Slava
name: Trevisani, Emilio
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: By the Parisi-Sourlas conjecture, the critical point of a theory with random field (RF) disorder is described by a supersymmeric (SUSY) conformal field theory (CFT), related to a $d-2$ dimensional CFT without SUSY. Numerical studies indicate that this is true for the RF $ϕ^3$ model but not for RF $ϕ^4$ model in $d<5$ dimensions. Here we argue that the SUSY fixed point is not reached because of new relevant SUSY-breaking interactions. We use perturbative renormalization group in a judiciously chosen field basis, allowing systematic exploration of the space of interactions. Our computations agree with the numerical results for both cubic and quartic potential.
description: 16 pages, 2 figures; minor modifications, version accepted for publication in PRL
Electromagnetic Modeling of Lossy Interconnects From DC to High Frequencies With a Potential-Based Boundary Element Formulation
Creators: name: Sharma, Shashwat
name: Triverio, Piero
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computational Engineering, Finance, and Science (cs.CE)
subject: FOS: Computer and information sciences

description: The accurate electromagnetic modeling of both low- and high-frequency physics is crucial in the signal and power integrity analysis of electrical interconnects. The boundary element method (BEM) is appealing for lossy conductor modeling because it can capture the frequency-dependent variation of skin depth with only a surface-based discretization of the structure. Conventional BEM formulations rely on the mutual coupling of electric and magnetic fields, and can become inaccurate or unstable at low frequencies. We develop a new full-wave BEM formulation based on potentials which can accurately model lossy conductors from exactly DC to very high frequencies. A new set of simple boundary conditions is proposed along with a modified Lorenz gauge to ensure that the proposed formulation has a stable condition number down to DC. Moreover, coupling the potential-based integral equations to a circuit model allows the straightforward extraction of network parameters. Realistic numerical examples at both the chip and package level demonstrate the accuracy and stability of the proposed method from DC to high frequencies, beyond the capabilities of state-of-the-art BEM formulations based on fields.
description: Submitted to the IEEE Transactions on Microwave Theory and Techniques
Spin Squeezing Induced Enhancement of Sensitivity of an Atomic Clock using Coherent Population Trapping
Creators: name: Li, Jinyang
name: da Silva, Gregório R. M.
name: Kain, Schuyler
name: Pati, Gour
name: Tripathi, Renu
name: Shahriar, Selim M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The coherent population trapping (CPT) effect is used for making compact atomic clocks. There are two types of CPT clocks: the one in which the Raman beams are applied continuously and the one in which two CPT pulses separated by a dark period are applied (Ramsey scheme). It is obvious that the technique of spin squeezing can only be applied to the Ramsey CPT clock to enhance the sensitivity. However, it is not apparent how to adapt to the CPT clock the protocols for the microwave clock using one-axis-twist squeezing (OATS), since the Ramsey CPT clock is not trivially equivalent to the Ramsey microwave clock. In this paper, we show explicitly how to adapt two protocols using OATS, namely the Schrödinger cat state protocol (SCSP) and the generalization thereof, and the echo squeezing protocol (ESP), to the CPT clock. The ESP magnifies the phase shift by a factor of the square-root of (N/e), while the SCSP magnifies the phase shift by a factor of N/2 , making it able to achieve a higher sensitivity in the presence of excess noise.
description: 32 pages, 5 figures
Explainable Artificial Intelligence to Detect Image Spam Using Convolutional Neural Network
Creators: name: Zhang, Zhibo
name: Damiani, Ernesto
name: Hamadi, Hussam Al
name: Yeun, Chan Yeob
name: Taher, Fatma
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: Image spam threat detection has continually been a popular area of research with the internet's phenomenal expansion. This research presents an explainable framework for detecting spam images using Convolutional Neural Network(CNN) algorithms and Explainable Artificial Intelligence (XAI) algorithms. In this work, we use CNN model to classify image spam respectively whereas the post-hoc XAI methods including Local Interpretable Model Agnostic Explanation (LIME) and Shapley Additive Explanations (SHAP) were deployed to provide explanations for the decisions that the black-box CNN models made about spam image detection. We train and then evaluate the performance of the proposed approach on a 6636 image dataset including spam images and normal images collected from three different publicly available email corpora. The experimental results show that the proposed framework achieved satisfactory detection results in terms of different performance metrics whereas the model-independent XAI algorithms could provide explanations for the decisions of different models which could be utilized for comparison for the future study.
description: Under review by International Conference on Cyber Resilience (ICCR), Dubai 2022
The formation and heating of chromospheric fibrils in a radiation-MHD simulation
Creators: name: Druett, M. K.
name: Leenaarts, J.
name: Carlsson, M.
name: Szydlarski, M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Aims: We examine the movements of mass elements within dense fibrils using passive tracer particles (corks) in order to understand fibril creation and destruction processes. Methods: Simulated fibrils were selected at times when they were visible in an H$α$ image proxy. The corks were selected within fibril H$α$ formation regions. From this set, a cork was selected, and the field line passing through it was constructed. Other fibrilar corks close to this fieldline were also selected. Pathlines were constructed, revealing the locations of the mass elements forward and backward in time. The forces acting on these mass elements were analysed. Results: The main process of fibrilar loading in the simulation is different to the mass loading scenario in which waves steepen into shocks and push material upwards along the fieldlines from near their footpoints. Twisted low lying fieldlines were destabilised and then they untwisted, lifting the material trapped above their apexes via the Lorentz force. Subsequently, the majority of the mass drained down the fieldlines towards one or both footpoints under gravity. Material with large horizontal velocities could also elevated in rising fieldlines, creating somewhat parabolic motions, but material was not generally moving upward along a stationary magnetic fieldline during loading. Conclusions: The processes observed in the simulation are plausible additional scenarios. Criteria for observing such events are described. It is desirable that our simulations can also form more densely-packed fibrils from material fed from the base of field footpoints. Experimental parameters required to achieve this are discussed.
description: Submitted to A&A
A crowdsourced dataset of aerial images with annotated solar photovoltaic arrays and installation metadata
Creators: name: Kasmi, Gabriel
name: Saint-Drenan, Yves-Marie
name: Trebosc, David
name: Jolivet, Raphaël
name: Leloux, Jonathan
name: Sarr, Babacar
name: Dubus, Laurent
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Photovoltaic (PV) energy generation plays a crucial role in the energy transition. Small-scale PV installations are deployed at an unprecedented pace, and their integration into the grid can be challenging since public authorities often lack quality data about them. Overhead imagery is increasingly used to improve the knowledge of residential PV installations with machine learning models capable of automatically mapping these installations. However, these models cannot be easily transferred from one region or data source to another due to differences in image acquisition. To address this issue known as domain shift and foster the development of PV array mapping pipelines, we propose a dataset containing aerial images, annotations, and segmentation masks. We provide installation metadata for more than 28,000 installations. We provide ground truth segmentation masks for 13,000 installations, including 7,000 with annotations for two different image providers. Finally, we provide installation metadata that matches the annotation for more than 8,000 installations. Dataset applications include end-to-end PV registry construction, robust PV installations mapping, and analysis of crowdsourced datasets.
description: 12 pages, 3 figures, 7 tables, revised preprint resubmitted to Scientific Data
Eikonal amplitudes from curved backgrounds
Creators: name: Adamo, Tim
name: Cristofoli, Andrea
name: Tourkine, Piotr
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Eikonal exponentiation in QFT describes the emergence of classical physics at long distances in terms of a non-trivial resummation of infinitely many diagrams. Long ago, 't Hooft proposed a beautiful correspondence between ultra-relativistic scalar eikonal scattering and one-to-one scattering in a background shockwave space-time, bypassing the need to resum. In this spirit, we propose here a covariant method for computing one-to-one amplitudes in curved background space-times which gives rise what we conjecture to be a general expression for the eikonal amplitude. We show how the one-to-one scattering amplitude for scalars on any stationary space-time reduces to a boundary term that captures the long-distance behavior of the background and has the structure of an exponentiated eikonal amplitude. In the case of scalar scattering on Schwarzschild, we recover the known results for gravitational scattering of massive scalars in the eikonal regime. For Kerr, we find a remarkable exponentiation of the tree-level amplitude for gravitational scattering between a massive scalar and a massive particle of infinite spin. This amplitude exhibits a Kawai-Lewellen-Tye-like factorization, which we use to evaluate the eikonal amplitude in momentum space, and study its analytic properties.
description: 30 pages, 9 figures. v2: typos corrected, references added; v3: more typos corrected; v4: version accepted for publication
The Early Dark Sector, the Hubble Tension, and the Swampland
Creators: name: McDonough, Evan
name: Lin, Meng-Xiang
name: Hill, J. Colin
name: Hu, Wayne
name: Zhou, Shengjia
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider the interplay of the Early Dark Energy (EDE) model, the Swampland Distance Conjecture (SDC), and cosmological parameter tensions. EDE is a proposed resolution of the Hubble tension relying upon a near-Planckian scalar field excursion, while the SDC predicts an exponential sensitivity of masses of other fields to such an excursion, $m\propto e^{-c|Δϕ|/M_{\rm pl}}$ with $c\sim{\cal O}(1)$. Meanwhile, EDE is in tension with large-scale structure (LSS) data, due to shifts in the standard $Λ$CDM parameters necessary to fit the cosmic microwave background (CMB). One might hope that a proper treatment of the model, e.g., accounting for the SDC, may ameliorate the tension with LSS. Motivated by these considerations, we introduce the Early Dark Sector (EDS) model, wherein the mass of dark matter is exponentially sensitive to super-Planckian field excursions of the EDE scalar. The EDS model exhibits new phenomenology in both the early and late universe, the latter due to an EDE-mediated dark matter self-interaction. This dark matter-philic "fifth force", while constrained to be small, remains active in the late universe and is not screened in virialized halos. We find that the new interaction with dark matter partially resolves the LSS tension. However, the marginalized posteriors are nonetheless consistent with $f_{\rm EDE}=0$ at 95$\%$ CL once the Dark Energy Survey Year 3 measurement of $S_8$ is included. We study constraints on the model from Atacama Cosmology Telescope data, and find a factor of two improvement on the error bar on the SDC parameter $c$, along with an increased preference for the EDE component. We discuss the implications of these constraints for the SDC, and find the tightest observational constraints to date on a swampland parameter, suggesting that an EDE description of cosmological data is in tension with the SDC.
description: v2: version published in Phys. Rev. D
Planck scale displacement of a connected mirror pair: an energy measurement in a gravitational field
Creators: name: Kowalski, Frank V.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: Reflection of a particle from a mirror pair that is fixed to a platform which falls freely in a gravitational field is shown to infer displacement of the center of mass of this platform of order the Planck length. This displacement and its relationship to the wave and particle nature of reflection in such an energy measurement is elucidated using harmonic motion of the mirror pair.
description: 5 pages, 2 figures
Accelerating the Discovery of Light Dark Matter
Creators: name: Izaguirre, Eder
name: Krnjaic, Gordan
name: Schuster, Philip
name: Toro, Natalia
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We analyze the present status of sub-GeV thermal dark matter annihilating through Standard Model mixing and identify a small set of future experiments that can decisively test these scenarios.
description: 4 pages text + bibliography. 2 figures
Locality and Analyticity of the Crossing Symmetric Dispersion Relation
Creators: name: Chowdhury, Debapriyo
name: Haldar, Parthiv
name: Zahed, Ahmadullah
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: This paper discusses the locality and analyticity of the crossing symmetric dispersion relation (CSDR). Imposing locality constraints on the CSDR gives rise to a local and fully crossing symmetric expansion of scattering amplitudes, dubbed as Feynman block expansion. A general formula is provided for the contact terms that emerge from the expansion. The analyticity domain of the expansion is also derived analogously to the Lehmann-Martin ellipse. Our observation of type-II super-string tree amplitude suggests that the Feynman block expansion has a bigger analyticity domain and better convergence.
description: v2: 31 pages, 7 figures, the version to appear in JHEP
Gaussian Process Koopman Mode Decomposition
Creators: name: Kawashima, Takahiro
name: Hino, Hideitsu
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: In this paper, we propose a nonlinear probabilistic generative model of Koopman mode decomposition based on an unsupervised Gaussian process. Existing data-driven methods for Koopman mode decomposition have focused on estimating the quantities specified by Koopman mode decomposition, namely, eigenvalues, eigenfunctions, and modes. Our model enables the simultaneous estimation of these quantities and latent variables governed by an unknown dynamical system. Furthermore, we introduce an efficient strategy to estimate the parameters of our model by low-rank approximations of covariance matrices. Applying the proposed model to both synthetic data and a real-world epidemiological dataset, we show that various analyses are available using the estimated parameters.
description: 32 pages, 4 figures, to appear in Neural Computation
Quantum Computing Approach for Energy Optimization in a Prosumer Community
Creators: name: Mastroianni, Carlo
name: Scarcello, Luigi
name: Settino, Jacopo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: This paper presents a quantum approach for the formulation and solution of the prosumer problem, i.e., the problem of minimizing the energy cost incurred by a number of users in an energy community, while addressing the constraints given by the balance of energy and the user requirements. As the problem is NP-complete, a hybrid quantum/classical algorithm could help to acquire a significant speedup, which is particularly useful when the problem size is large. This work describes the steps through which the problem can be transformed, reformulated and given as an input to Quantum Approximate Optimization Algorithm (QAOA), and reports some experimental results, in terms of the quality of the solution and time to achieve it, obtained with a quantum simulator, when varying the number of constraints and, correspondingly, the number of qubits.
Biased random walk on random networks in presence of stochastic resetting: Exact results
Creators: name: Sarkar, Mrinal
name: Gupta, Shamik
Publisher: name: arXiv
Year: 2022
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We consider biased random walks on random networks constituted by a random comb comprising a backbone with quenched-disordered random-length branches. The backbone and the branches run in the direction of the bias. For the bare model as also when the model is subject to stochastic resetting, whereby the walkers on the branches reset with a constant rate to the respective backbone sites, we obtain exact stationary-state static and dynamic properties for a given disorder realization of branch lengths sampled following an arbitrary distribution. We derive a criterion to observe in the stationary state a non-zero drift velocity along the backbone. For the bare model, we discuss the occurrence of a drift velocity that is non-monotonic as a function of the bias, becoming zero beyond a threshold bias because of walkers trapped at very long branches. Further, we show that resetting allows the system to escape trapping, resulting in a drift velocity that is finite at any bias.
description: To appear as a Letter in J. Phys. A: Math. Theor
Cascade donor-acceptor organic ferroelectric layers, between graphene sheets, for solar cell applications
Creators: name: Wierzbowska, Malgorzata
name: Wawrzyniak-Adamczewska, Malgorzata
Publisher: name: arXiv
Year: 2015
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Organic ferroelectric layers sandwiched between the graphene sheets are presented as a model of the solar cell. The investigated systems display many advantageous properties: 1) the cascade energy-levels alignment, 2) simultaneous donor and acceptor character depending on the charge-carrier direction, 3) the charge-transfer excitonic type, 4) the induced polarization of the electrodes, leading to a substantial work-function change of the anode and cathode - around +/-1.5 eV, respectively.
description: accepted in RSC Advances
Stable compounds in the CaO-Al2O3 system at high pressures
Creators: name: Marchenko, Ekaterina I.
name: Oganov, Artem R.
name: Mazhnik, Efim A.
name: Eremin, Nikolay N.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Using evolutionary crystal structure prediction algorithm USPEX, we showed that at pressures of the Earth's lower mantle CaAl2O4 is the only stable calcium aluminate. At pressures above 7.0 GPa it has the CaFe2O4-type structure and space group Pnma. This phase is one of prime candidate aluminous phases in the lower mantle of the Earth. We show that at low pressures 5CaO * 3Al2O3 (C5A3) with space group Cmc21, CaAl4O7 (C2/c) and CaAl2O4 (P21/m) structures are stable at pressures of up to 2.1, 1.8 and 7.0 GPa respectively. The previously unknown structure of the orthorhombic 'CA-III' phase is also found from our calculations. This phase is metastable and has a layered structure with space group P21212.
The False Alarms induced by Gaussian Noise in Gravitational Wave Detectors
Creators: name: Morras, Gonzalo
name: Siles, Jose Francisco Nuño
name: Garcia-Bellido, Juan
name: Morales, Ester Ruiz
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Gaussian noise is an irreducible component of the background in gravitational wave (GW) detectors. Although stationary Gaussian noise is uncorrelated in frequencies, we show that there is an important correlation in time when looking at the matched filter signal to noise ratio (SNR) of a template, with a typical autocorrelation time that depends on the template and the shape of the noise power spectral density (PSD). Taking this correlation into account, we compute from first principles the false alarm rate (FAR) of a template in Gaussian noise, defined as the number of occurrences per unit time that the template's matched filter SNR goes over a threshold $ρ$. We find that the Gaussian FAR can be well approximated by the usual expression for uncorrelated noise, if we replace the sampling rate by an effective sampling rate that depends on the parameters of the template, the noise PSD and the threshold $ρ$. This results in a minimum SNR threshold that has to be demanded to a given GW trigger, if we want to keep events generated from Gaussian noise below a certain FAR. We extend the formalism to multiple detectors and to the analysis of GW events. We apply our method to the GW candidates added in the GWTC-3 catalog, and discuss the possibility that GW200308\_173609 and GW200322\_091133 could be generated by Gaussian noise fluctuations.
description: 22 pages, 11 figures
The Influence of Dataset Partitioning on Dysfluency Detection Systems
Creators: name: Bayerl, Sebastian P.
name: Wagner, Dominik
name: Nöth, Elmar
name: Bocklet, Tobias
name: Riedhammer, Korbinian
Publisher: name: arXiv
Year: 2022
Subjects: subject: Audio and Speech Processing (eess.AS)
subject: Computation and Language (cs.CL)
subject: Sound (cs.SD)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: This paper empirically investigates the influence of different data splits and splitting strategies on the performance of dysfluency detection systems. For this, we perform experiments using wav2vec 2.0 models with a classification head as well as support vector machines (SVM) in conjunction with the features extracted from the wav2vec 2.0 model to detect dysfluencies. We train and evaluate the systems with different non-speaker-exclusive and speaker-exclusive splits of the Stuttering Events in Podcasts (SEP-28k) dataset to shed some light on the variability of results w.r.t. to the partition method used. Furthermore, we show that the SEP-28k dataset is dominated by only a few speakers, making it difficult to evaluate. To remedy this problem, we created SEP-28k-Extended (SEP-28k-E), containing semi-automatically generated speaker and gender information for the SEP-28k corpus, and suggest different data splits, each useful for evaluating other aspects of methods for dysfluency detection.
description: Accepted at the 25th International Conference on Text, Speech and Dialogue (TSD 2022)
Deep Reinforcement Learning for Cryptocurrency Trading: Practical Approach to Address Backtest Overfitting
Creators: name: Gort, Berend Jelmer Dirk
name: Liu, Xiao-Yang
name: Sun, Xinghang
name: Gao, Jiechao
name: Chen, Shuaiyu
name: Wang, Christina Dan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Statistical Finance (q-fin.ST)
subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (cs.LG)
subject: FOS: Economics and business
subject: FOS: Computer and information sciences
subject: I.2.6
subject: 68T07,

description: Designing profitable and reliable trading strategies is challenging in the highly volatile cryptocurrency market. Existing works applied deep reinforcement learning methods and optimistically reported increased profits in backtesting, which may suffer from the false positive issue due to overfitting. In this paper, we propose a practical approach to address backtest overfitting for cryptocurrency trading using deep reinforcement learning. First, we formulate the detection of backtest overfitting as a hypothesis test. Then, we train the DRL agents, estimate the probability of overfitting, and reject the overfitted agents, increasing the chance of good trading performance. Finally, on 10 cryptocurrencies over a testing period from 05/01/2022 to 06/27/2022 (during which the crypto market crashed two times), we show that the less overfitted deep reinforcement learning agents have a higher return than that of more overfitted agents, an equal weight strategy, and the S&P DBM Index (market benchmark), offering confidence in possible deployment to a real market.
Pinning of interfaces in random media
Creators: name: Dirr, Nicolas
name: Dondl, Patrick W.
name: Scheutzow, Michael
Publisher: name: Technische Universität Berlin
Year: 2011
Subjects: subject: 510 Mathematik
subject: QEW
subject: phase boundaries
subject: pinning
subject: random environment

description: Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
description: This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
description: For a model for the propagation of a curvature sensitive interface in a time independent random medium, as well as for a linearized version which is commonly referred to as Quenched Edwards– Wilkinson equation, we prove existence of a stationary positive supersolution at non-vanishing applied load. This leads to the emergence of a hysteresis that does not vanish for slow loading, even though the local evolution law is viscous (in particular, the velocity of the interface in the model is linear in the driving force).
Early Gesture and Vocabulary Development in Infant Siblings of Children with Autism Spectrum Disorder
Creators: name: Iverson, Jana M.
name: Northrup, Jessie B.
name: Koterba, Erin A.
name: Parladé, Meaghan V.
name: Leezenbaum, Nina B.
name: West, Kelsey L.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2018

description: This study examined longitudinal growth in gestures and words in infants at heightened (HR) vs. low risk (LR) for ASD. The MacArthur-Bates Communicative Development Inventory was administered monthly from 8 to 14 months and at 18 and 24 months to caregivers of 14 HR infants diagnosed with ASD (HR-ASD), 27 HR infants with language delay (HR-LD), 51 HR infants with no diagnosis (HR-ND), and 28 LR infants. Few differences were obtained between LR and HR-ND infants, but HR-LD and HR-ASD groups differed in initial skill levels and growth patterns. While HR-LD infants grew at rates comparable to LR and HR-ND infants, growth was attenuated in the HR-ASD group, with trajectories progressively diverging from all other groups.
The exact Schur index in closed form
Creators: name: Pan, Yiwen
name: Peelaers, Wolfger
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The Schur limit of the superconformal index of a four-dimensional N = 2 superconformal field theory encodes rich physical information about the protected spectrum of the theory. For a Lagrangian model, this limit of the index can be computed by a contour integral of a multivariate elliptic function. However, surprisingly, so far it has eluded exact evaluation in closed, analytical form. In this paper we propose an elementary approach to bring to heel a large class of these integrals by exploiting the ellipticity of their integrand. Our results take the form of a finite sum of (products of) the well-studied flavored Eisenstein series. In particular, we derive a compact formula for the fully flavored Schur index of all theories of class S of type a1, we put forward a conjecture for the unflavored Schur indices of all N=4 super Yang-Mills theories with gauge group SU(N), and we present closed-form expressions for the index of various other gauge theories of low ranks. We also discuss applications to non-Lagrangian theories, modular properties, and defect indices.
description: 65 pages; v2: minor clarifications, refs added; v3: typos corrected
Spin triplet superconducting pairing in doped MoS$_2$
Creators: name: Wang, Jingyao
name: Zhang, Xiao
name: Ma, Runyu
name: Yang, Guang
name: Castro, Eduardo V.
name: Ma, Tianxing
Publisher: name: arXiv
Year: 2022
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Searching for triplet superconductivity has been pursued intensively in a broad field of material science and quantum information for decades. Nevertheless, these novel states remain rare. Within a simplified effective three-orbital model, we reveal a spin triplet pairing in doped MoS$_2$ by employing both the finite temperature determinant quantum Monte Carlo approach and the ground state constrained-phase quantum Monte Carlo method. In a wide filling region of $\avg{n}=0.60-0.80$ around charge neutrality $\avg{n}=2/3$, the $f$-wave pairing dominates over other symmetries. The pairing susceptibility strongly increases as the on-site Coulomb interaction increases, and it is insensitive to spin-orbit coupling.
description: Accepted for publication as a Regular Article in Physical Review B
CHIME Discovery of a Binary Pulsar with a Massive Non-Degenerate Companion
Creators: name: Andersen, Bridget C.
name: Fonseca, Emmanuel
name: McKee, J. W.
name: Meyers, B. W.
name: Luo, Jing
name: Tan, C. M.
name: Stairs, I. H.
name: Kaspi, Victoria M.
name: van Kerkwijk, M. H.
name: Bhardwaj, Mohit
name: Boyle, P. J.
name: Crowter, Kathryn
name: Demorest, Paul B.
name: Dong, Fengqui A.
name: Good, Deborah C.
name: Kaczmarek, Jane F.
name: Leung, Calvin
name: Masui, Kiyoshi W.
name: Naidu, Arun
name: Ng, Cherry
name: Patel, Chitrang
name: Pearlman, Aaron B.
name: Pleunis, Ziggy
name: Rafiei-Ravandi, Masoud
name: Rahman, Mubdi
name: Ransom, Scott M.
name: Smith, Kendrick M.
name: Tendulkar, Shriharsh P.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Of the more than $3{,}000$ radio pulsars currently known, only ${\sim}300$ are in binary systems, and only five of these consist of young pulsars with massive non-degenerate companions. We present the discovery and initial timing, accomplished using the Canadian Hydrogen Intensity Mapping Experiment telescope (CHIME), of the sixth such binary pulsar, PSR J2108+4516, a $0.577$-s radio pulsar in a 269-day orbit of eccentricity 0.09 with a companion of minimum mass $11$ M$_{\odot}$. Notably, the pulsar undergoes periods of substantial eclipse, disappearing from the CHIME $400{-}800$ MHz observing band for a large fraction of its orbit, and displays significant dispersion measure and scattering variations throughout its orbit, pointing to the possibility of a circumstellar disk or very dense stellar wind associated with the companion star. Subarcsecond resolution imaging with the Karl G. Jansky Very Large Array unambiguously demonstrates that the companion is a bright, $V \simeq 11$ OBe star, EM* UHA 138, located at a distance of $3.26(14)$ kpc. Archival optical observations of \companion{} approximately suggest a companion mass ranging from $17.5$ M$_{\odot} < M_{\rm c} < 23$ M$_{\odot}$, in turn constraining the orbital inclination angle to $50.3^{\circ} \lesssim i \lesssim 58.3^{\circ}$. With further multi-wavelength followup, PSR J2108+4516 promises to serve as another rare laboratory for the exploration of companion winds, circumstellar disks, and short-term evolution through extended-body orbital dynamics.
description: 20 pages, 12 figures, accepted by ApJ
Entropy of Hilbert metrics and length spectrum of Hitchin representations in $\mathrm{PSL}(3,\mathbb{R})$
Creators: name: Tholozan, Nicolas
Publisher: name: arXiv
Year: 2015
Subjects: subject: Metric Geometry (math.MG)
subject: Differential Geometry (math.DG)
subject: Dynamical Systems (math.DS)
subject: Geometric Topology (math.GT)
subject: FOS: Mathematics

description: We prove a sharp inequality between the Blaschke and Hilbert distance on a proper convex domain: for any two points $x$ and $y$, \[d^B(x,y) < d^H(x,y) +1.\] We obtain two interesting consequences: the first one is the volume entropy rigidity for Hilbert geometries : for any proper convex domain of $\mathbb{R}\mathbf{P}^n$, the volume of a ball of radius $R$ grows at most like $e^{(n-1)R}$. The second consequence is the following fact: for any Hitchin representation of a surface group into $\mathrm{PSL}(3,\mathbb{R})$, there exists a Fuchsian representation $j$ in $\mathrm{PSL}(2,\mathbb{R})$ such that the length spectrum of $j$ is uniformly smaller than the length spectrum of $ρ$.
Changes in polarization dictate necessary approximations for modeling electronic de-excitation intensity: an application to X-ray emission
Creators: name: Roychoudhury, Subhayan
name: Cunha, Leonardo A.
name: Head-Gordon, Martin
name: Prendergast, David
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Chemical Physics (physics.chem-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: We systematically investigate the underlying relations among different levels of approximation for simulating electronic de-excitations, with a focus on modeling X-ray emission spectroscopy (XES). Using Fermi's golden rule and explicit modeling of the initial, core-excited state and the final, valence-hole state, we show that XES can be accurately modeled by using orbital optimization for the various final states within a Slater-determinant framework. However, in this paper, we introduce a much cheaper approach reliant only on a single self-consistent field for all the final states, and show that it is typically sufficient. Further approximations reveal that these fundamentally many-body transitions can be reasonably approximated by projections of ground state orbitals, but that the ground state alone is insufficient. Furthermore, except in cases where the core-ionization induces negligible changes in polarization, linear-response approaches within the adiabatic approximation will have difficulty in accurately modeling de-excitation to the core level. Therefore, change in the net dipole moment of the valence electrons can serve as a metric for the validity of the linear-response approximation.
Seeking security through rubber intercropping: A case study from northeastern Thailand
Creators: name: Polthanee, Anan
Publisher: name: Research and Technology Transfer Affairs Division.Khon Kaen University
Year: 2016
Subjects: Immature rubber, mature rubber, intercropping, banana, cassava, coffee, Calopogonium caeruleum

description: Asia-Pacific Journal of Science and Technology, 21, 3, 1-11
A Stack-of-Tasks Approach Combined with Behavior Trees: a New Framework for Robot Control
Creators: name: Domínguez, David Cáceres
name: Iannotta, Marco
name: Stork, Johannes A.
name: Schaffernicht, Erik
name: Stoyanov, Todor
Publisher: name: arXiv
Year: 2022
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: Stack-of-Tasks (SoT) control allows a robot to simultaneously fulfill a number of prioritized goals formulated in terms of (in)equality constraints in error space. Since this approach solves a sequence of Quadratic Programs (QP) at each time-step, without taking into account any temporal state evolution, it is suitable for dealing with local disturbances. However, its limitation lies in the handling of situations that require non-quadratic objectives to achieve a specific goal, as well as situations where countering the control disturbance would require a locally suboptimal action. Recent works address this shortcoming by exploiting Finite State Machines (FSMs) to compose the tasks in such a way that the robot does not get stuck in local minima. Nevertheless, the intrinsic trade-off between reactivity and modularity that characterizes FSMs makes them impractical for defining reactive behaviors in dynamic environments. In this letter, we combine the SoT control strategy with Behavior Trees (BTs), a task switching structure that addresses some of the limitations of the FSMs in terms of reactivity, modularity and re-usability. Experimental results on a Franka Emika Panda 7-DOF manipulator show the robustness of our framework, that allows the robot to benefit from the reactivity of both SoT and BTs.
Network Analysis of Cosmic Structures : Network Centrality and Topological Environment
Creators: name: Hong, Sungryong
name: Dey, Arjun
Publisher: name: arXiv
Year: 2015
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We apply simple analyses techniques developed for the study of complex networks to the study of the cosmic web, the large scale galaxy distribution. In this paper, we measure three network centralities (ranks of topological importance), Degree Centrality (DC), Closeness Centrality (CL), and Betweenness Centrality (BC) from a network built from the Cosmological Evolution Survey (COSMOS) catalog. We define 8 galaxy populations according to the centrality measures; Void, Wall, and Cluster by DC, Main Branch and Dangling Leaf by BC, and Kernel, Backbone, and Fracture by CL. We also define three populations by voronoi tessellation density to compare these with the DC selection. We apply the topological selections to galaxies in the (photometric) redshift range $0.91
description: 19 pages, 11 figures, Accepted for publication in MNRAS