cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Reduced dynamics with Poincaré symmetry in an open quantum system
Creators: name: Matsumura, Akira
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider how the reduced dynamics of an open quantum system coupled to an environment admits the Poincaré symmetry. The reduced dynamics is described by a dynamical map, which is given by tracing out the environment from the total unitary evolution without initial correlations. We investigate the dynamical map which is invariant under the Poincaré group. Based on the unitary representation theory of the Poincaré group, we develop a systematic way to give such a dynamical map. Using this way, we derive the dynamical map of a massive particle with a finite spin and a massless particle with a finite spin and a nonzero momentum. The dynamical map of a spinless massive particle is exemplified and the conservation of the Poincaré generators is discussed. We then find the map with the Poincaré invariance and the four-momentum conservation. Further, we show that the conservation of the angular momentum and the boost operator makes the map of a spinless massive particle unitary
description: 31 pages, 1 table
Predicting the Sun's Polar Magnetic Fields with a Surface Flux Transport Model
Creators: name: Upton, Lisa
name: Hathaway, David H.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The Sun's polar magnetic fields are directly related to solar cycle variability. The strength of the polar fields at the start (minimum) of a cycle determine the subsequent amplitude of that cycle. In addition, the polar field reversals at cycle maximum alter the propagation of galactic cosmic rays throughout the heliosphere in fundamental ways. We describe a surface magnetic flux transport model that advects the magnetic flux emerging in active regions (sunspots) using detailed observations of the near-surface flows that transport the magnetic elements. These flows include the axisymmetric differential rotation and meridional flow and the non-axisymmetric cellular convective flows (supergranules) all of which vary in time in the model as indicated by direct observations. We use this model with data assimilated from full-disk magnetograms to produce full surface maps of the Sun's magnetic field at 15-minute intervals from 1996 May to 2013 July (all of sunspot cycle 23 and the rise to maximum of cycle 24). We tested the predictability of this model using these maps as initial conditions, but with daily sunspot area data used to give the sources of new magnetic flux. We find that the strength of the polar fields at cycle minimum and the polar field reversals at cycle maximum can be reliably predicted up to three years in advance. We include a prediction for the cycle 24 polar field reversal.
description: 12 pages, 9 figures, ApJ accepted
The solar chromosphere observed at 1 Hz and 0."2 resolution
Creators: name: Lipartito, Isabel
name: Judge, Philip
name: Reardon, Kevin
name: Cauzzi, Gianna
Publisher: name: arXiv
Year: 2014
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We recently reported extremely rapid changes in chromospheric fine structure observed using the IBIS instrument in the red wing of H alpha. Here, we examine data obtained during the same observing run (August 7 2010), of a mature active region NOAA 11094. We analyze more IBIS data including wavelength scans and data from the Solar Dynamics Observatory, all from within a 30 minute interval. Using a slab radiative transfer model, we investigate the physical nature of fibrils in terms of tube-like vs. sheet-like structures. Principal Component Analysis shows that the very rapid H alpha variations in the line wings depend mostly on changes of line width and line shift, but for Ca II 854.2 the variations are dominated by changes in column densities. The tube model must be rejected for a small but significant class of fibrils undergoing very rapid changes. If our wing data arise from the same structures leading to "type II spicules", our analysis calls into question much recent work. Instead the data do not reject the hypothesis that some fibrils are optical superpositions of plasma collected into sheets. We review how Parker's theory of tangential discontinuities naturally leads to plasma collecting into sheets, and show that the sheet picture is falsifiable. Chromospheric fine structures seem to be populated by both tubes and sheets. We assess the merits of spectral imaging versus slit spectroscopy for future studies.
description: to appear in the Astrophysical Journal
A scheme for simulating multi-level phase change photonics materials
Creators: name: Wang, Yunzheng
name: Ning, Jing
name: Lu, Li
name: Bosman, Michel
name: Simpson, Robert E.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Cellular Automata and Lattice Gases (nlin.CG)
subject: FOS: Physical sciences

description: Chalcogenide phase change materials (PCMs) have been extensively applied in data storage, and they are now being proposed for high resolution displays, holographic displays, reprogrammable photonics, and all-optical neural networks. These wide-ranging applications all exploit the radical property contrast between the PCMs different structural phases, extremely fast switching speed, long-term stability, and low energy consumption. Designing PCM photonic devices requires an accurate model to predict the response of the device during phase transitions. Here, we describe an approach that accurately predicts the microstructure and optical response of phase change materials during laser induced heating. The framework couples the Gillespie Cellular Automata approach for modelling phase transitions with effective medium theory and Fresnel equations. The accuracy of the approach is verified by comparing the PCM optical response and microstructure evolution with the results of nanosecond laser switching experiments. We anticipate that this approach to simulating the switching response of PCMs will become an important component for designing and simulating programmable photonics devices. The method is particularly important for predicting the multi-level optical response of PCMs, which is important for all-optical neural networks and PCM-programmable perceptrons.
description: 26 pages, 6 figures
Survey _men on Menstruation.csv.zip
Creators: name: Rao, Ratna
name: Patil, Surekha
name: Joshi, Akash
Publisher: name: figshare
Year: 2023
Subjects: Cultural studies of nation and region

description: The data is survey reponses of survey conducted on menstruation. The survey aimed to understand the perceptions of Indian men and women.
Experimental quantum imaging distillation with undetected light
Creators: name: Fuenzalida, Jorge
name: Basset, Marta Gilaberte
name: Töpfer, Sebastian
name: Torres, Juan P.
name: Gräfe, Markus
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Imaging based on the induced coherence effect makes use of photon pairs to obtain information of an object without detecting the light that probes it. While one photon illuminates the object, only its partner is detected, so no measurement of coincidence events are needed. The sought-after object's information is revealed observing a certain interference pattern on the detected photon. Here we demonstrate experimentally that this imaging technique can be made resilient to noise. We introduce an imaging distillation approach based on the interferometric modulation of the signal of interest. We show that our scheme can generate a high-quality image of an object even against noise levels up to 250 times the actual signal of interest. We also include a detailed theoretical explanation of our findings.
description: 18 pages, 6 figures, and 1 table + 11 pages, 3 figures, and 1 table
The Weyl Tensor of Gradient Ricci Solitons
Creators: name: Cao, Xiaodong
name: Tran, Hung
Publisher: name: arXiv
Year: 2013
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 53C44 (Primary), 53C21, 53C25(Secondary)

description: This paper derives new identities for the Weyl tensor on a gradient Ricci soliton, particularly in dimension four. First, we prove a Bochner-Weitzenböck type formula for the norm of the self-dual Weyl tensor and discuss its applications, including connections between geometry and topology. In the second part, we are concerned with the interaction of different components of Riemannian curvature and (gradient and Hessian of) the soliton potential function. The Weyl tensor arises naturally in these investigations. Applications here are rigidity results.
description: 42 pages
Detecting light-induced Floquet band gaps of graphene via trARPES
Creators: name: Broers, Lukas
name: Mathey, Ludwig
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We propose a realistic regime to detect the light-induced topological band gap in graphene via time-resolved angle-resolved photoelectron spectroscopy (trARPES), that can be achieved with current technology. The direct observation of Floquet-Bloch bands in graphene is limited by low-mobility, Fourier-broadening, laser-assisted photoemission (LAPE), probe-pulse energy-resolution bounds, space-charge effects and more. We characterize a regime of low driving frequency and high amplitude of the circularly polarized light that induces an effective band gap at the Dirac point that exceeds the Floquet zone. This circumvents limitations due to energy resolutions and band broadening. The electron distribution across the Floquet replica in this limit allow for distinguishing LAPE replica from Floquet replica. We derive our results from a dissipative master equation approach that gives access to two-point correlation functions and the electron distribution relevant for trARPES measurements.
Indistinguishable telecom band photons from a single erbium ion in the solid state
Creators: name: Ourari, Salim
name: Dusanowski, Łukasz
name: Horvath, Sebastian P.
name: Uysal, Mehmet T.
name: Phenicie, Christopher M.
name: Stevenson, Paul
name: Raha, Mouktik
name: Chen, Songtao
name: Cava, Robert J.
name: de Leon, Nathalie P.
name: Thompson, Jeff D.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: Atomic defects in the solid state are a key component of quantum repeater networks for long-distance quantum communication. Recently, there has been significant interest in rare earth ions, in particular Er$^{3+}$ for its telecom-band optical transition, but their application has been hampered by optical spectral diffusion precluding indistinguishable single photon generation. In this work we implant Er$^{3+}$ into CaWO$_4$, a material that combines a non-polar site symmetry, low decoherence from nuclear spins, and is free of background rare earth ions, to realize significantly reduced optical spectral diffusion. For shallow implanted ions coupled to nanophotonic cavities with large Purcell factor, we observe single-scan optical linewidths of 150 kHz and long-term spectral diffusion of 63 kHz, both close to the Purcell-enhanced radiative linewidth of 21 kHz. This enables the observation of Hong-Ou-Mandel interference between successively emitted photons with high visibility, measured after a 36 km delay line. We also observe spin relaxation times $T_1$ = 3.7 s and $T_2$ > 200 $μ$s, with the latter limited by paramagnetic impurities in the crystal instead of nuclear spins. This represents a significant step towards the construction of telecom-band quantum repeater networks with single Er$^{3+}$ ions.
Controlled self-assembly of periodic and aperiodic cluster crystals
Creators: name: Barkan, Kobi
name: Engel, Michael
name: Lifshitz, Ron
Publisher: name: arXiv
Year: 2014
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: Soft particles are known to overlap and form stable clusters that self-assemble into periodic crystalline phases with density-independent lattice constants. We use molecular dynamics simulations in two dimensions to demonstrate that, through a judicious design of an isotropic pair potential, one can control the ordering of the clusters and generate a variety of phases, including decagonal and dodecagonal quasicrystals. Our results confirm analytical predictions based on a mean-field approximation, providing insight into the stabilization of quasicrystals in soft macromolecular systems, and suggesting a practical approach for their controlled self-assembly in laboratory realizations using synthesized soft-matter particles.
description: Supplemental Material can be obtained through the author's website at: http://www.tau.ac.il/~ronlif/pubs/ClusterCrystals-Supp.pdf
A JWST transmission spectrum of a nearby Earth-sized exoplanet
Creators: name: Lustig-Yaeger, J.
name: Fu, G.
name: May, E. M.
name: Ceballos, K. N. Ortiz
name: Moran, S. E.
name: Peacock, S.
name: Stevenson, K. B.
name: López-Morales, M.
name: MacDonald, R. J.
name: Mayorga, L. C.
name: Sing, D. K.
name: Sotzen, K. S.
name: Valenti, J. A.
name: Adams, J.
name: Alam, M. K.
name: Batalha, N. E.
name: Bennett, K. A.
name: Gonzalez-Quiles, J.
name: Kirk, J.
name: Kruse, E.
name: Lothringer, J. D.
name: Rustamkulov, Z.
name: Wakeford, H. R.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The critical first step in the search for life on exoplanets over the next decade is to determine whether rocky planets transiting small M-dwarf stars possess atmospheres and, if so, what processes sculpt them over time. Because of its broad wavelength coverage and improved resolution compared to previous methods, spectroscopy with JWST offers a new capability to detect and characterize the atmospheres of Earth-sized, M-dwarf planets. Here we use JWST to independently validate the discovery of LHS 475b, a warm (586 K), 0.99 Earth-radius exoplanet, interior to the habitable zone, and report a precise 2.9-5.3 um transmission spectrum. With two transit observations, we rule out primordial hydrogen-dominated and cloudless pure methane atmospheres. Thus far, the featureless transmission spectrum remains consistent with a planet that has a high-altitude cloud deck (similar to Venus), a tenuous atmosphere (similar to Mars), or no appreciable atmosphere at all (akin to Mercury). There are no signs of stellar contamination due to spots or faculae. Our observations demonstrate that JWST has the requisite sensitivity to constrain the secondary atmospheres of terrestrial exoplanets with absorption features <50 ppm, and that our current atmospheric constraints speak to the nature of the planet itself, rather than instrumental limits.
description: A co-first author paper Lustig-Yaeger and Fu et al., Nature Astronomy (2023), Comments welcome
mNGS of bronchoalveolar lavage fluid from children with severe pneumonia in PICU
Creators: name: 刘婷彦(Liu Tingyan)
Publisher: name: CNGB
Year: 2023
Subjects: Metagenomic assembly
Multispecies
Medical

description: Severe pneumonia due to lower respiratory tract infections (LRTIs) is a significant cause of morbidity and mortality in children. Noninfectious respiratory syndromes resembling LRTIs can complicate the diagnosis and may also make targeted therapy difficult because of the difficulty of identifying LRTI pathogens. In the present study, a highly sensitive metagenomic next-generation sequencing (mNGS) approach was used to characterize the microbiome of bronchoalveolar lavage fluid (BALF) in children with severe lower pneumonia and identify pathogenic microorganisms that may cause severe pneumonia. The purpose of this study was to use mNGS to explore the potential microbiomes of children with severe pneumonia in a PICU.
Hubble tension and matter inhomogeneities: a theoretical perspective
Creators: name: Martín, Marco San
name: Rubio, Carlos
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We have studied how local density perturbations could reconcile the Hubble tension. We reproduced a local void through a perturbed FLRW metric with a potential $Φ$ which depends on both time and space. This method allowed us to obtain a perturbed luminosity distance, which is compared with both local and cosmological data. However, when constraining local cosmological parameters with previous results, we found that neither $Λ$CDM nor $Λ(ω)$CDM cannot solve the Hubble tension.
description: 12 pages
title:  Effectiveness of a Practice Regimen for Decreasing Floor Rise Time in Older Adults
Creators: name: Gibbs, Deborah Waldschmidt
Publisher: name: Old Dominion University
publisherIdentifier: https://ror.org/04zjtrb98
publisherIdentifierScheme: ROR
Year: 2003

description: Some older adults experience extended periods of time lying on the floor waiting for help to arrive because they can not rise up independently (Campbell et al., 1990; Nevitt, Cummings, and Hudes, 1991). In many of these cases the older adults are not seriously injured, yet they lack the ability to rise up (Tinetti and Speechley, 1989; Vellas, Cayla, Bocquet, Pemille, and Albarede, 1987). Body Recall, an exercise program that teaches floor rising to older adults, advocates practicing getting up from the floor as a method for retaining this ability. The benefit of Body Recall is only anecdotal and has not been examined in a controlled study. Thus, the purpose of this study was to determine if teaching and practicing floor rising skills, such as those described in the Body Recall program, will decrease the time it takes for older adults to rise from the floor.

Nineteen subjects (ten training subjects with an average age of 83.4 years, and 9 control subjects with an average age of 84.8 years) completed the investigation. The training group participated in an exercise class that used the Body Recall technique of teaching floor rising. The class met 3 days a week for 6 weeks and consisted of a warmup, range of motion exercises and floor rising practice. Measures were taken pre- and post-training to analyze strength, flexibility and floor rise times. After six weeks the training group experienced a significant decrease (42%) in floor rise time. One-repetition maximum (I-RM) scores for leg press and chest press did not change, and sit and reach scores did not change. The control group did not have any significant changes in the variables, but showed a trend toward an increase in floor rise time. Therefore, a six-week class of floor rising practice proved to be effective in decreasing floor rise time in the study group, without a change in strength or flexibility.
title: Влияние ведомственных интересов нефтяников на проектирование, строительство и эксплуатацию сети автодорог Ханты-Мансийского округа (конец 1970-х – начало 1990-х гг.)
title: Influence of Departmental Interests of Oil Producers on the Design, Construction and Operation of the Khanty-Mansiysk Okrug Road Network (late 1970s – early 1990s)
Creators: name: Веселов, Севостьян Игоревич
Publisher: name: Издательский центр СурГУ
Year: 2022

description: Целью статьи является анализ позитивного и негативного влияния нефтяников
на организационно-технические и проектные решения в условиях модернизации ведомственных
автодорог Среднего Приобья в конце 1970-х – начале 1990-х гг. Впервые введены в оборот данные
о протяженности автодорог круглогодичного и сезонного действия по ремонтно-строительным трестам объединений «Сургутнефтегаз» и «Юганскнефтегаз». Раскрыта сущность ведомственных интересов нефтяников, их влияние на проектирование, строительство и эксплуатацию опорной сети автодорог общего пользования в конце 1980-х – начале 1990-х гг. (после передачи части ведомственных
автодорог на баланс Минавтодора РСФСР). Автором прослеживается влияние состояния городских
и межпромысловых автодорог на деятельность ведомственного и общественного автотранспорта
в условиях роста аварийности в районах Среднего Приобья.
description: The purpose of the article is to analyze positive and negative influence of oil producers on
organizational, technical and design solutions under the conditions of upgrading the Middle Ob departmental
roads in the late 1970s – early 1990s. Data on the stretch of year-round and seasonal roads of repair and construction divisions of “Surgutneftegaz” and “Yuganskneftegaz” are introduced for the first time. The article
also expands on the departmental interests of oil producers, their influence on the design, construction and
operation of the basic public road network in the late 1980s – early 1990s after putting a part of the departmental roads onto the books of the RSFSR Minavtodor. The author traces how the state of urban and interfield roads influences on operation of departmental and public transport under the conditions of accidence
risk growth in the Middle Ob region.
Koszul Feynman Categories
Creators: name: Kaufmann, Ralph M.
name: Ward, Benjamin C.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Algebraic Topology (math.AT)
subject: Category Theory (math.CT)
subject: FOS: Mathematics

description: A cubical Feynman category, introduced by the authors in previous work, is a category whose functors to a base category $\mathcal{C}$ behave like operads in $\mathcal{C}$. In this note we show that every cubical Feynman category is Koszul. The upshot is an explicit, minimal cofibrant resolution of any cubical Feynman category, which can be used to model $\infty$ versions of generalizations of operads for both graph based and non-graph based examples.
description: final version with minor revisions
Near-Optimal Mean-Variance Controls under Two-time-scale Formulations and Applications
Creators: name: Yang, Zhixin
name: Yin, G.
name: Wang, Le Yi
name: Zhang, Hongwei
Publisher: name: arXiv
Year: 2014
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: Although the mean-variance control was initially formulated for financial portfolio management problems in which one wants to maximize expected return and control the risk, our motivations also stem from highway vehicle platoon controls that aim to maximize highway utility while ensuring zero accident. This paper develops near-optimal mean-variance controls of switching diffusion systems. To reduce the computational complexity, with motivations from earlier work on singularly perturbed Markovian systems \cite{SethiZ94,Yin&Zhang,GZB}, we use a two-time-scale formulation to treat the underlying systems, which is represented by use of a small parameter. As the small parameter goes to 0, we obtain a limit problem. Using the limit problem as a guide, we construct controls for the original problem, and show that the control so constructed is nearly optimal.
Sim2Real for Soft Robotic Fish via Differentiable Simulation
Creators: name: Zhang, John Z.
name: Zhang, Yu
name: Ma, Pingchuan
name: Nava, Elvis
name: Du, Tao
name: Arm, Philip
name: Matusik, Wojciech
name: Katzschmann, Robert K.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Robotics (cs.RO)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Accurate simulation of soft mechanisms under dynamic actuation is critical for the design of soft robots. We address this gap with our differentiable simulation tool by learning the material parameters of our soft robotic fish. On the example of a soft robotic fish, we demonstrate an experimentally-verified, fast optimization pipeline for learning the material parameters from quasi-static data via differentiable simulation and apply it to the prediction of dynamic performance. Our method identifies physically plausible Young's moduli for various soft silicone elastomers and stiff acetal copolymers used in creation of our three different robotic fish tail designs. We show that our method is compatible with varying internal geometry of the actuators, such as the number of hollow cavities. Our framework allows high fidelity prediction of dynamic behavior for composite bi-morph bending structures in real hardware to millimeter-accuracy and within 3 percent error normalized to actuator length. We provide a differentiable and robust estimate of the thrust force using a neural network thrust predictor; this estimate allows for accurate modeling of our experimental setup measuring bollard pull. This work presents a prototypical hardware and simulation problem solved using our differentiable framework; the framework can be applied to higher dimensional parameter inference, learning control policies, and computational design due to its differentiable character.
description: Published at IROS 2022. 8 pages, 9 figures
Generative Adversarial Networks to infer velocity components in rotating turbulent flows
Creators: name: Li, Tianyi
name: Buzzicotti, Michele
name: Biferale, Luca
name: Bonaccorso, Fabio
Publisher: name: arXiv
Year: 2023
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: Chaotic Dynamics (nlin.CD)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Inference problems for two-dimensional snapshots of rotating turbulent flows are studied. We perform a systematic quantitative benchmark of point-wise and statistical reconstruction capabilities of the linear Extended Proper Orthogonal Decomposition (EPOD) method, a non-linear Convolutional Neural Network (CNN) and a Generative Adversarial Network (GAN). We attack the important task of inferring one velocity component out of the measurement of a second one, and two cases are studied: (I) both components lay in the plane orthogonal to the rotation axis and (II) one of the two is parallel to the rotation axis. We show that EPOD method works well only for the former case where both components are strongly correlated, while CNN and GAN always outperform EPOD both concerning point-wise and statistical reconstructions. For case (II), when the input and output data are weakly correlated, all methods fail to reconstruct faithfully the point-wise information. In this case, only GAN is able to reconstruct the field in a statistical sense. The analysis is performed using both standard validation tools based on $L_2$ spatial distance between the prediction and the ground truth and more sophisticated multi-scale analysis using wavelet decomposition. Statistical validation is based on standard Jensen-Shannon divergence between the probability density functions, spectral properties and multi-scale flatness.
The Micromegas Project for the ATLAS Upgrade
Creators: name: Iakovidis, Georgios
Publisher: name: arXiv
Year: 2013
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Micromegas is one of the detector technologies (along with the small Thin Gap Chambers) that has been chosen for precision tracking and triggering purposes of the ATLAS muon forward detectors in the view of LHC luminosity increase. To fulfill the requirements of such upgrade, several prototype micromegas detectors were tested in recent test beam campaigns with high energy hadron beams at CERN. Performance studies and results on spatial resolution for perpendicular and inclined tracks, efficiency, as well detector performance and comparison to simulation in a magnetic field are presented. Moreover, an overview of detector performance after neutron, X-ray, gammas and alphas exposure and construction achievements of large area micromegas detectors are presented.
Amenable wreath products with non almost finite actions of mean dimension zero
Creators: name: Joseph, Matthieu
Publisher: name: arXiv
Year: 2023
Subjects: subject: Dynamical Systems (math.DS)
subject: Group Theory (math.GR)
subject: Operator Algebras (math.OA)
subject: FOS: Mathematics
subject: 37A15, 37B05, 20E08, 20E26, 20E15, 46L35

description: Almost finiteness was introduced in the seminal work of Kerr as an dynamical analogue of Z-stability in the Toms-Winter conjecture. In this article, we provide the first examples of minimal, topologically free actions of amenable groups that have mean dimension zero but are not almost finite. More precisely, we prove that there exists an infinite family of amenable wreath products that admit topologically free, minimal profinite actions on the Cantor space which fail to be almost finite. Furthermore, these actions have dynamical comparison. This intriguing new phenomenon shows that Kerr's dynamical analogue of Toms-Winter conjecture fails for minimal, topologically free actions of amenable groups. The notion of allosteric group holds a significant position in our study. A group is allosteric if it admits a minimal action on a compact space with an invariant ergodic probability measure that is topologically free but not essentially free. We study allostery of wreath products and provide the first examples of allosteric amenable groups.
description: 16 pages. Final version, to appear in Trans. Amer. Math. Soc
Distributed CONGEST Approximation of Weighted Vertex Covers and Matchings
Creators: name: Faour, Salwa
name: Fuchs, Marc
name: Kuhn, Fabian
Publisher: name: arXiv
Year: 2021
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: FOS: Computer and information sciences

description: We provide CONGEST model algorithms for approximating minimum weighted vertex cover and the maximum weighted matching. For bipartite graphs, we show that a $(1+\varepsilon)$-approximate weighted vertex cover can be computed deterministically in polylogarithmic time. This generalizes a corresponding result for the unweighted vertex cover problem shown in [Faour, Kuhn; OPODIS '20]. Moreover, we show that in general weighted graph families that are closed under taking subgraphs and in which we can compute an independent set of weight at least a $λ$-fraction of the total weight, one can compute a $(2-2λ+\varepsilon)$-approximate weighted vertex cover in polylogarithmic time in the CONGEST model. Our result in particular implies that in graphs of arboricity $a$, one can compute a $(2-1/a+\varepsilon)$-approximate weighted vertex cover. For maximum weighted matchings, we show that a $(1-\varepsilon)$-approximate solution can be computed deterministically in polylogarithmic CONGEST rounds (for constant $\varepsilon$). We also provide a more efficient randomized algorithm. Our algorithm generalizes results of [Lotker, Patt-Shamir, Pettie; SPAA '08] and [Bar-Yehuda, Hillel, Ghaffari, Schwartzman; PODC '17] for the unweighted case. Finally, we show that even in the LOCAL model and in bipartite graphs of degree $\leq 3$, if $\varepsilon<\varepsilon_0$ for some constant $\varepsilon_0>0$, then computing a $(1+\varepsilon)$-approximation for the unweighted minimum vertex cover problem requires $Ω\big(\frac{\log n}{\varepsilon}\big)$ rounds. This generalizes aresult of [Göös, Suomela; DISC '12], who showed that computing a $(1+\varepsilon_0)$-approximation in such graphs requires $Ω(\log n)$ rounds.
Nitrogen-enriched, highly-pressurized nebular clouds surrounding a super star cluster at cosmic noon
Creators: name: Pascale, Massimo
name: Dai, Liang
name: McKee, Christopher F.
name: Tsang, Benny T. -H.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Strong lensing offers a precious opportunity for studying the formation and early evolution of super star clusters that are rare in our cosmic backyard. The Sunburst Arc, a lensed Cosmic Noon galaxy, hosts a young super star cluster with escaping Lyman continuum radiation. Analyzing archival HST images and emission line data from VLT/MUSE and X-shooter, we construct a physical model for the cluster and its surrounding photoionized nebula. We confirm that the cluster is $\lesssim4\,$Myr old, is extremely massive $M_\star \sim 10^7\,M_\odot$ and yet has a central component as compact as several parsecs, and we find a gas-phase metallicity $Z=(0.22\pm0.03)\,Z_\odot$. The cluster is surrounded by $\gtrsim 10^5\,M_\odot$ of dense clouds that have been pressurized to $P\sim 10^9\,{\rm K}\,{\rm cm}^{-3}$ by perhaps stellar radiation at within ten parsecs. These should have large neutral columns $N_{\rm HI} > 10^{22.5}\,{\rm cm}^{-2}$ to survive rapid ejection by radiation pressure. The clouds are likely dusty as they show gas-phase depletion of silicon, and may be conducive to secondary star formation if $N_{\rm HI} > 10^{24}\,{\rm cm}^{-2}$ or if they sink further toward the cluster center. Detecting strong ${\rm N III]}λλ$1750,1752, we infer heavy nitrogen enrichment $\log({\rm N/O})=-0.21^{+0.10}_{-0.11}$. This requires efficiently retaining $\gtrsim 500\,M_\odot$ of nitrogen in the high-pressure clouds from massive stars heavier than $60\,M_\odot$ up to 4 Myr. We suggest a physical origin of the high-pressure clouds from partial or complete condensation of slow massive star ejecta, which may have important implication for the puzzle of multiple stellar populations in globular clusters.
description: 27 pages, 11 figures, Published in ApJ
A Hamiltonian splitting for the Vlasov-Maxwell system
Creators: name: Crouseilles, Nicolas
name: Einkemmer, Lukas
name: Faou, Erwan
Publisher: name: arXiv
Year: 2014
Subjects: subject: Numerical Analysis (math.NA)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: A new splitting is proposed for solving the Vlasov-Maxwell system. This splitting is based on a decomposition of the Hamiltonian of the Vlasov-Maxwell system and allows for the construction of arbitrary high order methods by composition (independent of the specific deterministic method used for the discretization of the phase space). Moreover, we show that for a spectral method in space this scheme satisfies Poisson's equation without explicitly solving it. Finally, we present some examples in the context of the time evolution of an electromagnetic plasma instability which emphasizes the excellent behavior of the new splitting compared to methods from the literature.
Crossover from exciton-polariton condensation to photon lasing in an optical trap
Creators: name: Pieczarka, Maciej
name: Biegańska, Dąbrówka
name: Schneider, Christian
name: Höfling, Sven
name: Klembt, Sebastian
name: Sęk, Grzegorz
name: Syperek, Marcin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: Optical trapping has been proven to be an effective method of separating exciton-polariton condensates from the incoherent high-energy excitonic reservoir located at the pumping laser position. This technique has significantly improved the coherent properties of exciton-polariton condensates, when compared to a quasi-homogeneous spot excitation scheme. Here, we compare two experimental methods on a sample, where a single spot excitation experiment allowed only to observe photonic lasing in the weak coupling regime. In contrast, the ring-shaped excitation resulted in the two-threshold behavior, where an exciton-polariton condensate manifests itself at the first and photon lasing at the second threshold. Both lasing regimes are trapped in an optical potential created by the pump. We interpret the origin of this confining potential in terms of repulsive interactions of polaritons with the reservoir at the first threshold and as a result of the excessive free-carrier induced refractive index change of the microcavity at the second threshold. This observation offers a way to achieve multiple phases of photonic condensates in samples, e.g., containing novel materials as an active layer, where two-threshold behavior is impossible to achieve with a single excitation spot.
description: 19 pages, 5 figures
Half of an image is enough for quality assessment
Creators: name: You, Junyong
name: Lin, Yuan
name: Korhonen, Jari
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Deep networks have demonstrated promising results in the field of Image Quality Assessment (IQA). However, there has been limited research on understanding how deep models in IQA work. This study introduces a novel positional masked transformer for IQA and provides insights into the contribution of different regions of an image towards its overall quality. Results indicate that half of an image may play a trivial role in determining image quality, while the other half is critical. This observation is extended to several other CNN-based IQA models, revealing that half of the image regions can significantly impact the overall image quality. To further enhance our understanding, three semantic measures (saliency, frequency, and objectness) were derived and found to have high correlation with the importance of image regions in IQA.
Coupling light into graphene plasmons through surface acoustic waves
Creators: name: Schiefele, Jürgen
name: Pedrós, Jorge
name: Sols, Fernando
name: Calle, Fernando
name: Guinea, Francisco
Publisher: name: arXiv
Year: 2013
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We propose a scheme for coupling laser light into graphene plasmons with the help of electrically generated surface acoustic waves. The surface acoustic wave forms a diffraction grating which allows to excite the long lived phonon-like branch of the hybridized graphene plasmon-phonon dispersion with infrared laser light. Our approach avoids patterning the graphene sheet, does not rely on complicated optical near-field techniques, and allows to electrically switch the coupling between far field radiation and propagating graphene plasmons.
description: 5 pages, 3 figures
Demonstration of Duality of Fractal Gravity Models by Scaling Symmetry
Creators: name: Chen, Yanguang
Publisher: name: arXiv
Year: 2021
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: A pair of fractal gravity models can be derived from the spatial interaction models based on entropy maximizing principle and allometric scaling law. The models can be expressed as dual form in mathematics and are important for analyzing and predicting spatial flows in network of cities. However, the dual relationship of urban gravity parameters has been an empirical relationship for a long time and lacks theoretical proof. This paper is devoted to proving the duality of fractal gravity models by means of ideas from scaling invariance. The results show that a fractal gravity model can be derived from its dual form. The observational data of interurban spatial flows of Beijing-Tianjin-Hebei region of China are employed to make a case study, lending a further support to the theoretical derivation. A conclusion can be reached that the duality of gravity models rests with scaling symmetry of fractal structure. This work may be helpful for understanding the theoretical essence and application direction of spatial interaction modeling.
description: 19 pages, 1 figure, 6 tables
Partial periodic quotient of groups acting on a hyperbolic space
Creators: name: Coulon, Rémi
Publisher: name: arXiv
Year: 2013
Subjects: subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 20F65, 20F50

description: In this article, we construct partial periodic quotients of groups which have a non-elementary acylindrical action on a hyperbolic space. In particular, we provide infinite quotients of mapping class groups where a fixed power of every pseudo-Anosov homeomorphism is identified with a periodic or reducible element.
description: 65 pages, 3 figures
Engineering Interlayer Hybridization in Energy Space via Dipolar Overlayers
Creators: name: Shao, Bin
name: Jiang, Xiao
name: Berges, Jan
name: Meng, Sheng
name: Huang, Bing
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The interlayer hybridization (IH) of van der Waals (vdW) materials is thought to be mostly associated with the unignorable interlayer overlaps of wavefunctions ($t$) in real space. Here, we develop a more fundamental understanding of IH by introducing a new physical quantity, the IH admixture ratio $α$. Consequently, an exotic strategy of IH engineering in energy space can be proposed, i.e., instead of changing t as commonly used, $α$ can be effectively tuned in energy space by changing the onsite energy difference ($2Δ$) between neighboring-layer states. In practice, this is feasible via reshaping the electrostatic potential of the surface by deposing a dipolar overlayer, e.g., crystalline ice. Our first-principles calculations unveil that IH engineering via adjusting $2Δ$ can greatly tune interlayer optical transitions in transition-metal dichalcogenide bilayers, switch different types of Dirac surface states in Bi$_2$Se$_3$ thin films, and control magnetic phase transition of charge density waves in 1H/1T-TaS$_2$ bilayers, opening new opportunities to govern the fundamental optoelectronic, topological, and magnetic properties of vdW systems beyond the traditional interlayer-distance or twisting engineering.
description: 12 pages, 4 figures
A Bayesian tune of the Herwig Monte Carlo event generator
Creators: name: La Cagnina, Salvatore
name: Kröninger, Kevin
name: Kluth, Stefan
name: Verbytskyi, Andrii
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The optimisation (tuning) of the free parameters of Monte Carlo event generators by comparing their predictions with data is important since the simulations are used to calculate experimental efficiency and acceptance corrections, or provide predictions for signatures of hypothetical new processes in experiments. We present a tuning procedure that is based on Bayesian reasoning and that allows for a proper statistical interpretation of the results. The parameter space is fully explored using Markov Chain Monte Carlo. We apply the tuning procedure to the Herwig7 event generator with both the cluster and the string hadronization models and a large set of measurements from hadronic Z-boson decays produced at LEP in $e^{+}e^{-}$ collisions. Furthermore, we introduce a coherent propagation of uncertainties from the realm of parameters to the realm of observables and we show the effects of including experimental correlations of the measurements. To allow comparison with the approaches of other groups, we repeat the tuning considering weights for individual measurements.
Growth modes and coupled morphological-compositional modulations in GaP1-xNx layers grown on nominally (001)-oriented Si substrates
Creators: name: Saddik, K. Ben
name: Fernandez-Garrido, S.
name: Volkov, R.
name: Grandal, J.
name: Borgardt, N.
name: Garcia, B. J.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We investigated the chemical beam epitaxy of GaP1-xNx to correlate the growth parameters with their properties when they are grown on nominally (001)-oriented Si substrates, as desired for the lattice-matched integration of optoelectronic devices with the standard Si technology. The growth mode as well as the chemical, morphological and structural properties of samples prepared using different growth temperatures and N precursor fluxes were analyzed by RHEED, XRD, RBS, NRA, EDX spectroscopy, AFM and TEM. Our results show that, up to x = 0.04, it is possible to synthesize smooth and chemically homogeneous GaP1-xNx layers with a high-structural quality in a 2D fashion, namely, layer-by-layer. For a given N mole fraction, the layer-by-layer growth mode is favored by lowering the growth temperature while decreasing the N precursor flux. As the flux of the N precursor is increased at a given temperature to enhance N incorporation, the quality of the layers degrades upon exceeding a temperature-dependent threshold; above this threshold, the growing layer experiences a growth mode transition from 2D to 3D after reaching a critical thickness of a few nm. Following that transition, the morphology and the chemical composition become modulated along the [110] direction with a period of several tens of nm. The surface morphology is then characterized by the formation of {113}-faceted wires, while the N concentration is enhanced at the troughs formed in between adjacent (113) and (-1-13) facets. We conclude on the feasibility of fabricating homogeneous thick GaP1-xNx layers lattice matched to Si (x = 0.021) or even with N content up to x=0.04. The possibility of exceeding a N mole fraction of 0.04 without inducing coupled morphological-compositional modulations has also been demonstrated when the layer thickness is kept below the critical value for the 2D-3D growth mode transition.
Interaction Quench in Nonequilibrium Luttinger Liquids
Creators: name: Dinh, Stéphane Ngo
name: Bagrets, Dmitry A.
name: Mirlin, Alexander D.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study the relaxation dynamics of a nonequilibrium Luttinger liquid after a sudden interaction switch-on ("quench"), focussing on a double-step initial momentum distribution function. In the framework of the non-equilibrium bosonization, the results are obtained in terms of singular Fredholm determinants that are evaluated numerically and whose asymptotics are found analytically. While the quasi-particle weights decay exponentially with time after the quench, this is not a relaxation into a thermal state, in view of the integrability of the model. The steady-state distribution emerging at infinite times retains two edges which support Luttinger-liquid-like power-law singularities smeared by dephasing. The obtained critical exponents and the dephasing length are found to depend on the initial nonequilibrium state.
description: 11 pages, 5 figures