cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A closer look at supernovae as seeds for galactic magnetization
Creators: name: Ntormousi, Evangelia
name: Del Sordo, Fabio
name: Cantiello, Matteo
name: Ferrara, Andrea
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Explaining the currently observed magnetic fields in galaxies requires relatively strong seeding in the early Universe. One theory proposes that magnetic fields of the order of $μ$G were expelled by supernova (SN) explosions after primordial, nG or weaker fields were amplified in stellar interiors. In this work, we calculate the maximum magnetic energy that can be injected in the interstellar medium by a stellar cluster of mass $M_{cl}$ based on what is currently known about stellar magnetism. We consider early-type stars and adopt either a Salpeter or a top-heavy IMF. For their magnetic fields, we adopt either a Gaussian or a bimodal distribution. The Gaussian model assumes that all massive stars are magnetized with $10^3 < \langle B_* \rangle < 10^4$ G, while the bimodal, consistent with observations of Milky Way stars, assumes only 5-10 per cent of OB stars have $10^3 < \langle B_* \rangle < 10^4$ G, while the rest have $10 < \langle B_* \rangle < 10^2$ G. We find that the maximum magnetic energy that can be injected by a stellar population is between $10^{-10}-10^{-7}$ times the total SN energy. The highest end of these estimates is about five orders of magnitude lower than what is usually employed in cosmological simulations, where about $10^{-2}$ of the SN energy is injected as magnetic. Pure advection of the stellar magnetic field by SN explosions is a good candidate for seeding a dynamo, but not enough to magnetize galaxies. Assuming SNe as main mechanism for galactic magnetization, the magnetic field cannot exceed an intensity of $10^{-7}$ G in the best-case scenario for a population of $10^{5}$ solar masses in a superbubble of 300 pc radius, while more typical values are between $10^{-10}-10^{-9}$~G. Therefore, other scenarios for galactic magnetization at high redshift need to be explored.
description: Accepted for publication in A&A letters
Induced earthquake source parameters, attenuation, and site effects from waveform envelopes in the Fennoscandian Shield
Creators: name: Eulenfeld, Tom
name: Hillers, Gregor
name: Vuorinen, Tommi A. T.
name: Wegler, Ulrich
Publisher: name: arXiv
Year: 2022
Subjects: subject: Geophysics (physics.geo-ph)
subject: FOS: Physical sciences

description: We analyze envelopes of 233 and 22 $M_{\text L}$0.0 to $M_{\text L}$1.8 earthquakes induced by two geothermal stimulations in the Helsinki, Finland, metropolitan area. We separate source spectra and site terms and determine intrinsic attenuation and the scattering strength of shear waves in the 3 Hz to 200 Hz frequency range using radiative transfer based synthetic envelopes. Displacement spectra yield scaling relations with a general deviation from self-similarity, with a stronger albeit more controversial signal from the weaker 2020 stimulation. The 2020 earthquakes also tend to have a smaller local magnitude compared to 2018 earthquakes with the same moment magnitude. We discuss these connections in the context of fluid effects on rupture speed or medium properties. Site terms demonstrate that the spectral amplification relative to two reference borehole sites is not neutral at the other sensors; largest variations are observed at surface stations at frequencies larger than 30 Hz. Intrinsic attenuation is exceptionally low with $Q_{\text i}^{-1}$ values down to $2.4\times 10^{-5}$ at 20 Hz, which allows the observation of a diffuse reflection at the ${\sim}$50 km deep Moho. Scattering strength is in the range of globally observed data with $Q_{\text{sc}}^{-1}$ between $10^{-3}$ and $10^{-4}$. The application of the employed Qopen analysis program to the 2020 data in a retrospective monitoring mode demonstrates its versatility as a seismicity processing tool. The diverse results have implications for scaling relations, hazard assessment and ground motion modeling, and imaging and monitoring using ballistic and scattered wavefields in the crystalline Fennoscandian Shield environment.
description: published in JGR: Solid Earth, v2: published version
The CO$_2$ Profile and Analytical Model for the Pioneer Venus Large Probe Neutral Mass Spectrometer
Creators: name: Mogul, Rakesh
name: Limaye, Sanjay S.
name: Way, Michael. J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: We present a significantly updated CO$_2$ altitude profile for Venus (64.2-0.9 km) and provide support for a potential deep lower atmospheric haze of particles (17 km and lower). We extracted this information by developing a new analytical model for mass spectra obtained by the Pioneer Venus Large Probe (PVLP) Neutral Mass Spectrometer (LNMS). Our model accounts for changes in LNMS configuration and output during descent and enables the disentanglement of isobaric species via a data fitting routine that adjusts for mass-dependent changes in peak shape. The model yields CO$_2$ in units of density (kg m-3), isotope ratios for $^{13}$C/$^{12}$C and $^{18}$O/$^{16}$O, and 14 measures of CO$_2$ density across 55.4-0.9 km, which represents the most complete altitude profile for CO$_2$ at 60 km towards the surface to date. The CO$_2$ density profile is also consistent with the pressure, temperature, and volumetric gas measurements from the PVLP and VeNeRa spacecraft. Nominal and low-noise operations for the LNMS mass analyzer are supported by the behaviors (e.g., ionization yields, fragmentation yields, and peak shapes) of several internal standards (e.g., CH$^{3+}$, CH$^{4+}$, $^{40}$Ar$^+$, $^{136}$Xe$^{2+}$, and $^{136}$Xe$^+$), which were tracked across the descent. Lastly, our review of the CO$_2$ profile and LNMS spectra reveals hitherto unreported partial and rapidly clearing clogs of the inlet in the lower atmosphere, along with several ensuing data spikes at multiple masses. Together, these observations suggest that atmospheric intake was impacted by particles at 17 km (and lower) and that rapid particle degradation at the inlet yielded a temporary influx of mass signals into the LNMS.
description: Accepted, Nov. 2022
Elko spinors revised
Creators: name: Romero, R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: It is shown that c-number elko spinors obey the massless Dirac equation and are unitarily equivalent to Weyl bispinors. Therefore, they do not constitute a new spinor type with mass dimension one.
description: Published version
Intrinsic growth (rmax) and generation time (T) estimates for the cetacean genera Sousa, Orcaella, and Neophocaena, in suport of IUCN red list assessments.
Creators: name: Moore, Jeffrey E., 1974-
Publisher: name: U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southwest Fisheries Science Center
Year: 2015
Subjects: subject: Cetacea populations--Estimates--Pacific Ocean--Mathematical models.
subject: IUCN red list of threatened species

description: A workshop was held May 20-21, 2015, in San Diego, California, USA, titled: 'Workshop to Assess/Re-Assess IUCN Red Listings for Indo-Pacific Species of Coastal Marine Small Cetaceans.' Species included were Orcaella brevirostris, O. heinsohni, Neophocaena asiaeorientalis, and two of the three Indo-Pacific Sousa species: S. chinensis and S. plumbea. Sousa sahulensis and Neophocaena phocaenoides were not assessed, largely for lack of information about these species. Red List assessments require estimates of generation time for a pristine population, i.e., one with stable age structure and abundance at carrying capacity such that the annual per-capita population growth rate is λ = exp(r) = 1. Let this generation time be denoted T₀. Estimating T0 for the above species is the primary goal of this analysis. Additionally, this analysis provides point estimates of the anthropogenic mortality rate required to reduce a population by 30%, 50%, or 80% over three generations (3T₀). These reductions warrant Vulnerable, Endangered, or Critically Endangered status, respectively, under the Red List criterion A; IUCN 2012).
Asher Ovadiah, Geometrie and Floral Patterns in Ancient Mosaics
Creators: name: Hellenkemper Salies, Gisela
Publisher: name: Bonner Jahrbücher
Year: 2020

description: Rezension zu: Asher Ovadiah, Geometrie and Floral Patterns in Ancient Mosaics. A Study of their Origin in the Mosaics from the Classical Period to the Age of Augustus. L’Erma di Bretschneider, Rom 1980. 205 Seiten, 119 Abbildungen auf 44 Tafeln
description: Bonner Jahrbücher, Bd. 181.1981: Bonner Jahrbücher
Connecting Solar Orbiter remote-sensing observations and Parker Solar Probe in-situ measurements with a numerical MHD reconstruction of the Parker spiral
Creators: name: Biondo, Ruggero
name: Bemporad, Alessandro
name: Pagano, Paolo
name: Telloni, Daniele
name: Reale, Fabio
name: Romoli, Marco
name: Andretta, Vincenzo
name: Antonucci, Ester
name: Da Deppo, Vania
name: De Leo, Yara
name: Fineschi, Silvano
name: Heinzel, Petr
name: Moses, Daniel
name: Naletto, Giampiero
name: Nicolini, Gianalfredo
name: Spadaro, Daniele
name: Stangalini, Marco
name: Teriaca, Luca
name: Landini, Federico
name: Sasso, Clementina
name: Susino, Roberto
name: Jerse, Giovanna
name: Uslenghi, Michela
name: Pancrazzi, Maurizio
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Plasma Physics (physics.plasm-ph)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: As a key feature, NASA's Parker Solar Probe (PSP) and ESA-NASA's Solar Orbiter (SO) missions cooperate to trace solar wind and transients from their sources on the Sun to the inner interplanetary space. The goal of this work is to accurately reconstruct the interplanetary Parker spiral and the connection between coronal features observed remotely by the Metis coronagraph on-board SO and those detected in situ by PSP at the time of the first PSP-SO quadrature of January 2021. We use the Reverse In-situ and MHD Approach (RIMAP), a hybrid analytical-numerical method performing data-driven reconstructions of the Parker spiral. RIMAP solves the MHD equations on the equatorial plane with the PLUTO code, using the measurements collected by PSP between 0.1 and 0.2 AU as boundary conditions. Our reconstruction connects density and wind speed measurements provided by Metis (3-6 solar radii) to those acquired by PSP (21.5 solar radii) along a single streamline. The capability of our MHD model to connect the inner corona observed by Metis and the super Alfvénic wind measured by PSP, not only confirms the research pathways provided by multi-spacecraft observations, but also the validity and accuracy of RIMAP reconstructions as a possible test bench to verify models of transient phenomena propagating across the heliosphere, such as coronal mass ejections, solar energetic particles and solar wind switchbacks.
description: Astronomy & Astrophysics, Solar Orbiter First Results (Nominal Mission Phase), (in press) DOI: 10.1051/0004-6361/202244535
The relation between optical and $γ$-ray emission in BL Lac sources
Creators: name: La Mura, G.
name: Gonzalez, J. Becerra
name: Chiaro, G.
name: Ciroi, S.
name: Otero-Santos, J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The relativistic jets produced by some Active Galactic Nuclei (AGNs) are among the most efficient persistent sources of non-thermal radiation and represent an ideal laboratory for studying high-energy interactions. In particular, when the relativistic jet propagates along the observer's line of sight, the beaming effect produces dominant signatures in the observed spectral energy distribution (SED), from the radio domain up to the highest energies, with the further possibility of resulting in radiation-particle multi-messenger associations. In this work, we investigate the relationships between the emission of $γ$ rays and the optical spectra of a sample of AGN, selected from BL Lac sources detected by the $Fermi$ Large Area Telescope ($Fermi$-LAT). We find that there is a close relationship between the optical and $γ$-ray spectral indices. Despite all the limitations due to the non-simultaneity of the data, this observation strongly supports a substantial role of Synchrotron-Self Compton (SSC) radiation in a single zone leptonic scenario for most sources. This result simplifies the application of theoretical models to explore the physical parameters of the jets in this type of sources.
description: 20 pages, 8 figures, published on MNRAS. Fixed error in target coordinates list
Wideband Optical Filters with Small Gap Coupled Subwavelength Metal Structures
Creators: name: Zhang, Boyang
name: Guo, Junpeng
name: Lindquist, Robert
name: Yin, Stuart
Publisher: name: arXiv
Year: 2012
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: In this letter, we show that the bandwidth of optical band-stop filters made of subwavelength metal structures can be significantly increased by the strong plasmonic near-field coupling through the corners of the periodic metal squares. The effect of small gap coupling on the spectral bandwidth is investigated by varying the gap size between the metal squares. An equivalent transmission line model is used to fit the transmission and reflection spectra of the metal filters. The transmission line model can characterize well the metal structures with the gap size larger than the near-field decay length. However, it fails to model the transmission and reflection spectra when the gap size reaches the decay range of the near-field in the small gaps.
Soft-input, soft-output joint detection and GRAND
Creators: name: Sarieddeen, Hadi
name: Médard, Muriel
name: Duffy, Ken. R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: Guessing random additive noise decoding (GRAND) is a maximum likelihood (ML) decoding method that identifies the noise effects corrupting code-words of arbitrary code-books. In a joint detection and decoding framework, this work demonstrates how GRAND can leverage crude soft information in received symbols and channel state information to generate, through guesswork, soft bit reliability outputs in log-likelihood ratios (LLRs). The LLRs are generated via successive computations of Euclidean-distance metrics corresponding to candidate noise-recovered words. Noting that the entropy of noise is much smaller than that of information bits, a small number of noise effect guesses generally suffices to hit a code-word, which allows generating LLRs for critical bits; LLR saturation is applied to the remaining bits. In an iterative (turbo) mode, the generated LLRs at a given soft-input, soft-output GRAND iteration serve as enhanced a priori information that adapts noise-sequence guess ordering in a subsequent iteration. Simulations demonstrate that a few turbo-GRAND iterations match the performance of ML-detection-based soft-GRAND in both AWGN and Rayleigh fading channels at a complexity cost that, on average, grows linearly (instead of exponentially) with the number of symbols.
description: To appear in the IEEE GLOBECOM 2022 proceedings
GRAND for Fading Channels using Pseudo-soft Information
Creators: name: Sarieddeen, Hadi
name: Médard, Muriel
name: Duffy, Ken. R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: Guessing random additive noise decoding (GRAND) is a universal maximum-likelihood decoder that recovers code-words by guessing rank-ordered putative noise sequences and inverting their effect until one or more valid code-words are obtained. This work explores how GRAND can leverage additive-noise statistics and channel-state information in fading channels. Instead of computing per-bit reliability information in detectors and passing this information to the decoder, we propose leveraging the colored noise statistics following channel equalization as pseudo-soft information for sorting noise sequences. We investigate the efficacy of pseudo-soft information extracted from linear zero-forcing and minimum mean square error equalization when fed to a hardware-friendly soft-GRAND (ORBGRAND). We demonstrate that the proposed pseudo-soft GRAND schemes approximate the performance of state-of-the-art decoders of CA-Polar and BCH codes that avail of complete soft information. Compared to hard-GRAND, pseudo-soft ORBGRAND introduces up to 10dB SNR gains for a target 10^-3 block-error rate.
description: To appear in the IEEE GLOBECOM 2022 proceedings. arXiv admin note: text overlap with arXiv:2207.10836
Microscopic Origin of the Electric Dzyaloshinskii-Moriya Interaction
Creators: name: Chen, Peng
name: Zhao, Hong Jian
name: Prosandeev, Sergey
name: Artyukhin, Sergey
name: Bellaiche, Laurent
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The microscopic origin of the electric Dzyaloshinskii-Moriya interaction (eDMI) is unveiled and discussed by analytical analysis and first-principles based calculations. As similar to the magnetic Dzyaloshinskii-Moriya interaction (mDMI), eDMI also originates from electron-mediated effect and more specifically from certain electron hoppings that are being activated due to certain local inversion symmetry breaking. However, the eDMI energy is found to be at least a third-order interaction in atomic displacements instead of bilinear in magnetic dipole moments for mDMI. Furthermore, the eDMI energy form is presented, and we find that novel electrical topological defects (namely, chiral electric bobbers) can arise from this eDMI. Thus unraveling the microscopic origin of eDMI has the potential to lead to, and explain, the discovery of novel polar topological phases.
description: 37 pages, 14 figures, 9 tables; Physical Review B accepted, see https://journals.aps.org/prb/accepted/89076K2fDde14e0d07313d31c483a35cd4d84b767
Mesoscopic Klein-Schwinger effect in graphene
Creators: name: Schmitt, A.
name: Vallet, P.
name: Mele, D.
name: Rosticher, M.
name: Taniguchi, T.
name: Watanabe, K.
name: Bocquillon, E.
name: Fève, G.
name: Berroir, J. M.
name: Voisin, C.
name: Cayssol, J.
name: Goerbig, M. O.
name: Troost, J.
name: Baudin, E.
name: Plaçais, B.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Strong electric field annihilation by particle-antiparticle pair creation, also known as the Schwinger effect, is a non-perturbative prediction of quantum electrodynamics. Its experimental demonstration remains elusive, as threshold electric fields are extremely strong and beyond current reach. Here, we propose a mesoscopic variant of the Schwinger effect in graphene, which hosts Dirac fermions with an approximate electron-hole symmetry. Using transport measurements, we report on universal 1d-Schwinger conductance at the pinchoff of ballistic graphene transistors. Strong pinchoff electric fields are concentrated within approximately 1 $μ$m of the transistor's drain, and induce Schwinger electron-hole pair creation at saturation. This effect precedes a collective instability toward an ohmic Zener regime, which is rejected at twice the pinchoff voltage in long devices. These observations advance our understanding of current saturation limits in ballistic graphene and provide a direction for further quantum electrodynamic experiments in the laboratory.
description: 39 pages, 13 figures, final version with extended discussion of the pinchoff effect in supplementary informations, abstract updated
Late time cosmological scenarios from scalar field with Gauss Bonnet and non-minimal kinetic couplings
Creators: name: Granda, L. N.
Publisher: name: arXiv
Year: 2011
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study a model of scalar field with kinetic terms non-minimally coupled to to the curvature, and the scalar field coupled to the Gauss Bonnet 4-dimensional invariant. A variety of solutions are found, giving rise to different cosmological scenarios. A unified description of early time matter (radiation) dominance with transitions to late time quintessence and phantom phases have been made. Among others, we found solutions unifying asymptotically the early power law behavior and late time cosmological constant. Solutions of Chaplygin gas and generalized Chaplygin gas cosmologies have also been found.
description: 25 pages
Fermi Level Tuning of Epitaxial Sb2Te3 Thin Films on Graphene by Regulating Intrinsic Defects and Substrate Transfer Doping
Creators: name: Jiang, Yeping
name: Sun, Y. Y.
name: Chen, Mu
name: Wang, Yilin
name: Li, Zhi
name: Song, Canli
name: He, Ke
name: Wang, Lili
name: Chen, Xi
name: Xue, Qi-Kun
name: Ma, Xucun
name: Zhang, S. B.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: High-quality Sb2Te3 films are obtained by molecular beam epitaxy on graphene substrate and investigated by in situ scanning tunneling microscopy/spectroscopy. Intrinsic defects responsible for the natural p-type conductivity of Sb2Te3 are identified to be the Sb vacancies and SbTe antisites in agreement with first-principles calculations. By minimizing defect densities, coupled with a transfer doping by the graphene substrate, the Fermi level of Sb2Te3 thin films can be tuned over the entire range of the bulk band gap. This establishes the necessary condition to explore topological insulator behaviors near the Dirac point.
description: 20 pages, 7 figures
Investigating datasets with high IRIS burst prevalence
Creators: name: Nelson, C. J.
name: Kleint, L.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Approximately 0.01 % of all Si IV 1394 A spectra sampled in 2013 and 2014 by the Interface Region Imaging Spectrograph (IRIS) have IRIS burst profiles. However, these events are not evenly distributed across datasets with 19.31 % of these spectra being identified in only six rasters. Here, we investigate five of these six datasets, to understand why they contain so many IRIS burst profiles. This research will help guide future targeted analyses of IRIS bursts. We analyse five datasets sampled by the IRIS satellite, studying both Si IV 1394 A spectra and 1400 A filter slit-jaw imager (SJI) data. IRIS burst profiles are identified through the use of an automated algorithm. Additionally, we study co-spatial line-of-sight photospheric magnetic field maps sampled by the Solar Dynamics Observatory's Helioseismic and Magnetic Imager (SDO/HMI) instrument. The majority of identified IRIS burst profiles (12401 out of 13904) found in the five datasets analysed here were localised to seven small regions in the time-distance domain (temporal durations of <4 hours and spatial lengths of <12" along the slit). The SJI data co-spatial to these regions contained long-lived or repetitive compact brightenings, matching the defined properties of UV bursts, which remained close to the IRIS slit throughout their evolutions. The IRIS burst profiles were not limited to the brightest pixels in the fields of view (FOVs) nor did they comprise the majority of bright (>500 DN/s) pixels. These IRIS burst profiles occurred co-spatial to evolving (e.g. cancelling) opposite polarity magnetic fields where magnetic reconnection is thought to be possible. More than 10 % of the IRIS burst profiles identified during the entirety of 2013 and 2014 are contained in just seven small regions in the time-distance domain where long-lived (lifetimes >10 minutes) or repetitive UV bursts occurred along the axis of the IRIS slit.
description: 12 pages, 9 figures, accepted to A&A
Gradient-descent quantum process tomography by learning Kraus operators
Creators: name: Ahmed, Shahnawaz
name: Quijandría, Fernando
name: Kockum, Anton Frisk
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: Machine Learning (cs.LG)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: We perform quantum process tomography (QPT) for both discrete- and continuous-variable quantum systems by learning a process representation using Kraus operators. The Kraus form ensures that the reconstructed process is completely positive. To make the process trace-preserving, we use a constrained gradient-descent (GD) approach on the so-called Stiefel manifold during optimization to obtain the Kraus operators. Our ansatz uses a few Kraus operators to avoid direct estimation of large process matrices, e.g., the Choi matrix, for low-rank quantum processes. The GD-QPT matches the performance of both compressed-sensing (CS) and projected least-squares (PLS) QPT in benchmarks with two-qubit random processes, but shines by combining the best features of these two methods. Similar to CS (but unlike PLS), GD-QPT can reconstruct a process from just a small number of random measurements, and similar to PLS (but unlike CS) it also works for larger system sizes, up to at least five qubits. We envisage that the data-driven approach of GD-QPT can become a practical tool that greatly reduces the cost and computational effort for QPT in intermediate-scale quantum systems.
description: 10 pages, 5 figures, Code and data available at https://github.com/quantshah/gd-qpt
A Simplified Method of the Assessment of Magnetic Anisotropy of Commonly Used Sapphire Substrates in SQUID Magnetometers
Creators: name: Gas, Katarzyna
name: Sawicki, Maciej
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Solid state wafers are indispensable components in material science as substrates for epitaxial homo- or hetero-structures or carriers for two-dimensional materials. However, a reliable determination of magnetic properties of nanomaterials in volume magnetometry is frequently affected by unexpectedly rich magnetism of these substrates, including significant magnetic anisotropy. Here, we describe a simplified experimental routine of magnetic anisotropy assessment, which we exemplify and validate for epi-ready sapphire wafers from various sources. Both the strength and the sign of magnetic anisotropy is obtained from carefully designed temperature dependent measurements, which mitigate all known pitfalls of volume SQUID magnetometry and are substantially faster than traditional approaches. Our measurements indicate that in all the samples two types of net paramagnetic contributions coexists with diamagnetism. The first one can be as strong as 10% of the base diamagnetism of sapphire [-3.7(1) x 10-7 emu/gOe], and, when exceeds 2% mark, it exhibits pronounced magnetic anisotropy with the easy axis oriented perpendicularly to the face of c-plane wafers. The other is much weaker but exhibit ferromagnetic-like appearance. These findings form an important message that non-standard magnetism of common substrates can significantly influence the results of precise magnetometry of nanoscale materials and its existence must be taken for granted by both industry and academia.
description: 17 pages, 4 figures
Fermi-LAT Detection of the Young SuperNova Remnant Tycho
Creators: name: Giordano, F.
name: Naumann-Godo, M.
name: Ballet, J.
name: Bechtol, K.
name: Funk, S.
name: Lande, J.
name: Mazziotta, M. N.
name: Rainò, S.
name: Tanaka, T.
name: Tibolla, O.
name: Uchiyama, Y.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: After almost three years of data taking in sky survey mode, the \emph{Fermi}-LAT has detected $γ$-ray emission toward the Tycho's Supernova Remnant (SNR). The Tycho SNR is among the youngest remnants in the Galaxy, originating from a Type Ia Supernova in AD 1572. The $γ$-ray integral flux from 400 MeV up to 100 GeV has been measured to be (3.5$\pm1.1_{stat}\pm0.7_{syst}$)$\times10^{-9}$ cm$^{-2}$s$^{-1}$ with a photon index of 2.3$\pm0.2_{stat}\pm0.1_{syst}$.
Temporary Flood Barriers
Creators: name: McCormack, Sarah M.
name: VanDyke, Chris
name: Suazo, Ashley
name: Kreis, Doug
Publisher: name: Kentucky Transportation Center, University of Kentucky
Year: 2012
Subjects: subject: Transportation Engineering

description: This report investigates the use and effectiveness of temporary flood barriers (TFBs) to mitigate the impacts of flood waters on Kentucky’s roadways. TFBs are structures, usually filled with sand, which are constructed along the edges of roadways and thus serve as a buffer against rising waters. In doing so, they can protect the structural soundness of roads, and ensure that roads remain open to traffic during flood events. The report is divided into four main sections. The first chapter introduces the concept of TFBs and notes situations in which they have been effectively deployed. The second chapter surveys the different kinds of TFBs currently available on the market and advances recommendations regarding which types are the most efficient and cost effective options for Kentucky. After this, the report investigates 8 potential sites at which TFBs may be deployed, in Kentucky’s Highway Districts 1 and 2. Two sites are recommended for further testing and potential implementation, and two alternative sites are suggested in case the preferred sites prove unworkable. The fourth chapter briefly explores the legal issues related to TFB usage. Because of the potential liability issues involved, to avoid legal action being taken against state employees in the case of TFBs failing and causing damage to adjacent property, the report recommends subcontracting the installation and maintenance of TFBs out to private entities. A final chapter summarizes all of the conclusions and recommendations of this report, and suggests that the Kentucky Transportation Cabinet move forward by a) inviting manufacturers to demonstrate their products onsite; and b) developing, in consultation with emergency managers and other officials at the local level, a comprehensive flood mitigation strategy that incorporates TFBs.
Agglomeration and welfare of the Krugman model in a continuous space
Creators: name: Ohtake, Kensuke
Publisher: name: arXiv
Year: 2022
Subjects: subject: Theoretical Economics (econ.TH)
subject: FOS: Economics and business

description: Two spatial equilibria, agglomeration and dispersion, in a continuous space core-periphery model are examined to discuss which equilibrium is socially preferred. It is shown that when transport cost is lower than a critical value, the agglomeration equilibrium is preferable in the sense of Scitovszky, while when the transport cost is above the critical value, the two equilibria can not be ordered in the sense of Scitovszky.
description: 16 pages
Herschel Far-Infrared and Sub-millimeter Photometry for the KINGFISH Sample of Nearby Galaxies
Creators: name: Dale, D. A.
name: Aniano, G.
name: Engelbracht, C. W.
name: Hinz, J. L.
name: Krause, O.
name: Montiel, E. J.
name: Roussel, H.
name: Appleton, P. N.
name: Armus, L.
name: Beirao, P.
name: Bolatto, A. D.
name: Brandl, B. R.
name: Calzetti, D.
name: Crocker, A. F.
name: Croxall, K. V.
name: Draine, B. T.
name: Galametz, M.
name: Gordon, K. D.
name: Groves, B. A.
name: Hao, C. -N.
name: Helou, G.
name: Hunt, L. K.
name: Johnson, B. D.
name: Kennicutt, R. C.
name: Koda, J.
name: Leroy, A. K.
name: Li, Y.
name: Meidt, S. E.
name: Miller, A. E.
name: Murphy, E. J.
name: Rahman, N.
name: Rix, H. -W.
name: Sandstrom, K. M.
name: Sauvage, M.
name: Schinnerer, E.
name: Skibba, R. A.
name: Smith, J. -D. T.
name: Tabatabaei, F. S.
name: Walter, F.
name: Wilson, C. D.
name: Wolfire, M. G.
name: Zibetti, S.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: New far-infrared and sub-millimeter photometry from the Herschel Space Observatory is presented for 61 nearby galaxies from the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) sample. The spatially-integrated fluxes are largely consistent with expectations based on Spitzer far-infrared photometry and extrapolations to longer wavelengths using popular dust emission models. Dwarf irregular galaxies are notable exceptions, as already noted by other authors, as their 500um emission shows evidence for a sub-millimeter excess. In addition, the fraction of dust heating attributed to intense radiation fields associated with photo-dissociation regions is found to be (21+/-4)% larger when Herschel data are included in the analysis. Dust masses obtained from the dust emission models of Draine & Li are found to be on average nearly a factor of two higher than those based on single-temperature modified blackbodies, as single blackbody curves do not capture the full range of dust temperatures inherent to any galaxy. The discrepancy is largest for galaxies exhibiting the coolest far-infrared colors.
description: Accepted for publication in ApJ
MOSEL Survey: Extremely weak outflows in EoR analogues at z=3-4
Creators: name: Gupta, Anshu
name: Tran, Kim-Vy
name: Mendel, Trevor
name: Harshan, Anishya
name: Forrest, Ben
name: Davies, R. L.
name: Wisnioski, Emily
name: Nanayakkara, Themiya
name: Kacprzak, Glenn G.
name: Kewley, Lisa J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: This paper presents deep K-band spectroscopic observations of galaxies at z=3-4 with composite photometric rest-frame Hb+[OIII] equivalent widths EW_0>600A, comparable to the EW of galaxies observed during the epoch of reionisation (EoR, z>6). The typical spectroscopic [OIII] EW_0 and stellar mass of our targets is ~ 700A and log(M_star/M_sun)=8.98. By stacking the [OIII] emission profiles, we find evidence of a weak broad component with F_broad/F_narrow ~ 0.2 and velocity width sigma_{broad} ~ 170 km/s. The strength and velocity width of the broad component does not change significantly with stellar mass and [OIII] EW_0 of the stacked sample. Assuming similar broad component profiles for [OIII] and Halpha emission, we estimate a mass loading factor ~0.2, similar to low stellar mass galaxies at z>1 even if the star formation rates of our sample is 10 times higher. We hypothesize that either the multi-phase nature of supernovae driven outflows or the suppression of winds in the extreme star-forming regime is responsible for the weak signature of outflows in the EoR analogues.
description: 14 pages, 9 figures, accepted for publication in MNRAS
Achievable Angles Between two Compressed Sparse Vectors Under Norm/Distance Constraints Imposed by the Restricted Isometry Property: A Plane Geometry Approach
Creators: name: Chang, Ling-Hua
name: Wu, Jwo-Yuh
Publisher: name: arXiv
Year: 2012
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: The angle between two compressed sparse vectors subject to the norm/distance constraints imposed by the restricted isometry property (RIP) of the sensing matrix plays a crucial role in the studies of many compressive sensing (CS) problems. Assuming that (i) u and v are two sparse vectors separated by an angle thetha, and (ii) the sensing matrix Phi satisfies RIP, this paper is aimed at analytically characterizing the achievable angles between Phi*u and Phi*v. Motivated by geometric interpretations of RIP and with the aid of the well-known law of cosines, we propose a plane geometry based formulation for the study of the considered problem. It is shown that all the RIP-induced norm/distance constraints on Phi*u and Phi*v can be jointly depicted via a simple geometric diagram in the two-dimensional plane. This allows for a joint analysis of all the considered algebraic constraints from a geometric perspective. By conducting plane geometry analyses based on the constructed diagram, closed-form formulae for the maximal and minimal achievable angles are derived. Computer simulations confirm that the proposed solution is tighter than an existing algebraic-based estimate derived using the polarization identity. The obtained results are used to derive a tighter restricted isometry constant of structured sensing matrices of a certain kind, to wit, those in the form of a product of an orthogonal projection matrix and a random sensing matrix. Follow-up applications to three CS problems, namely, compressed-domain interference cancellation, RIP-based analysis of the orthogonal matching pursuit algorithm, and the study of democratic nature of random sensing matrices are investigated.
description: submitted to IEEE Trans. Information Theory
An efficient Monte Carlo model for the slowing down of photoelectrons. Application to H-$α$ in exoplanet atmospheres
Creators: name: Muñoz, Antonio García
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Atomic and Molecular Clusters (physics.atm-clus)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: Photoelectrons, the fast electrons produced in the photoionization of planetary atmospheres, drive transformations in the atmospheric gas that are often inhibited by energy considerations for thermal electrons. The transformations include excitation and ionization of atoms and molecules, which affect the detectability of these gases and constrain the fraction of incident stellar radiation that transforms into heat. To gain insight into these important questions, we build a Monte Carlo model that solves the slowing down of photoelectrons in a gas with arbitrary amounts of H and He atoms and thermal electrons. Our novel multi-score scheme differs from similar tools in that it efficiently handles rare collisional channels, as in the case of low-abundance excited atoms that undergo superelastic and inelastic collisions. The model is validated and its performance demonstrated. Further, we investigate whether photoelectrons might affect the population of the excited hydrogen H(2) detected at some exoplanet atmospheres by transmission spectroscopy in the H-$α$ line. For the ultra-hot Jupiter HAT-P-32b, we find that photoelectron-driven excitation of H(2) is inefficient at the pressures probed by the line core but becomes significant (yet sub-dominant) deeper in the atmosphere where the line wings form. The contribution of photoelectrons to the destruction of H(2) either by collisional deexcitation or ionization is entirely negligible, a conclusion likely to hold for exoplanet atmospheres at large. Importantly, photoelectrons dominate the gas ionization at the altitudes probed by the H-$α$ line, a fact that will likely affect, even if indirectly, the population of H(2) and other tracers such as metastable helium. Future modeling of these excited levels should incorporate photoelectron-driven ionization.
description: Accepted for publication in Icarus
Mária Novotná, Die Bronzegefäße in der Slowakei
Creators: name: Matthäus, Hartmut
Publisher: name: Germania : Anzeiger der Römisch-Germanischen Kommission des Deutschen Archäologischen Instituts
Year: 2020

description: Rezension zu: Mária Novotná, Die Bronzegefäße in der Slowakei. Prähistorische Bronzefunde, Abteilung II, Band 11. Herausgegeben von Albrecht Jockenhövel und Wolf Kubach. Franz Steiner Verlag, Stuttgart 1991. ISBN 3-515-05548-7. VIII, 85 Seiten und 20 Tafeln
description: Germania : Anzeiger der Römisch-Germanischen Kommission des Deutschen Archäologischen Instituts, Bd. 75 Nr. 2 (1997)
Fractal characterization of rain-gauge networks and precipitations: an application in Central Italy
Creators: name: Capecchi, Valerio
name: Crisci, Alfonso
name: Melani, Samantha
name: Morabito, Marco
name: Politi, Paolo
Publisher: name: arXiv
Year: 2011
Subjects: subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: FOS: Physical sciences

description: The measuring stations of a geophysical network are often spatially distributed in an inhomogeneous manner. The areal inhomogeneity can be well characterized by the fractal dimension D_H of the network, which is usually smaller than the euclidean dimension of the surface, this latter equal to 2. The resulting dimensional deficit, (2-D_H), is a measure of precipitating events which cannot be detected by the network. The aim of the present study is to estimate the fractal dimension of a rain-gauge network in Tuscany (Central Italy) and to relate its dimension to the dimensions of daily rainfall events detected by a mixed satellite/radar methodology. We find that D_H = 1.85, while typical summer precipitations are characterized by a dimension much greater than the dimensional deficit 0.15.
description: 6 pages, 4 figures
Railroad Subgrade Support and Performance Indicators: A Review of Available Laboratory and In-Situ Testing Methods
Creators: name: McHenry, Michael T.
name: Rose, Jerry G.
Publisher: name: Kentucky Transportation Center, University of Kentucky
Year: 2012
Subjects: subject: Transportation Engineering

description: The quality and support of the subgrade portion of a railroad trackbed are vital to the overall performance of the track structure. The subgrade is an integral component of the track structure and its performance properties must be considered in order to effectively assess its influence on subsequent track quality. European and Asian railways are particularly advanced in implementing subgrade performance indicators into their track designs and assessments. As train speed and tonnage increase in the U.S., the evaluation and influence of subgrade performance will become even more paramount. There are numerous means of measuring and predicting subgrade performance. Both laboratory and in-situ test methods have been used. A review of available testing methods is presented herein in the context of railroad subgrade assessment. Discussion on the applicability of each test to the American railroad industry is also included. In-situ tests likely provide the greater advantage in railway engineering because results can typically be obtained quickly, more cost effectively, and with a larger data set. Newer rail-bound, continuous testing devices, while not testing the subgrade directly, are extremely convenient and will likely become more common in the future.
Analytical description of the diffusion in a cellular automaton with the Margolus neighbourhood in terms of the two-dimensional Markov chain
Creators: name: Kulagin, Anton
name: Shapovalov, Alexander
Publisher: name: arXiv
Year: 2022
Subjects: subject: Probability (math.PR)
subject: Cellular Automata and Lattice Gases (nlin.CG)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 37B15, 60J10, 60J20, 60J60

description: The one-parameter two-dimensional cellular automaton with the Margolus neighbourhood is analyzed based on the considering the projection of the stochastic movements of a single particle. Introducing the auxiliary random variable associated with the direction of the movement, we reduce the problem under consideration to the study of a two-dimensional Markov chain. The master equation for the probability distribution is derived and solved exactly using the probability generating function method. The probability distribution is expressed analytically in terms of Jacobi polynomials. The moments of the obtained solution allowed us to derive the exact analytical formula for the parametric dependence of the diffusion coefficient in the two-dimensional cellular automaton with the Margolus neighbourhood. Our analytic results agree with earlier empirical results of other authors and refine them. The results are of interest for the modelling two-dimensional diffusion using cellular automata especially for the multicomponent problem.
description: 28 pages, 6 figures, minor improvements
Fluorescing Coatings for Improved Inspection During Bridge Maintenance Painting
Creators: name: Meade, Bobby W.
name: Hopwood, Theodore
name: Palle, Sudhir
Publisher: name: Kentucky Transportation Center, University of Kentucky
Year: 2012
Subjects: subject: Transportation Engineering

description: Optically active pigments (OAPs) fluoresce under light exposures with wavelengths (nm) producing emissions in the visible spectra (380 to 740 nm). They are used as paint pigments to aid visual inspection of applied coatings for defects such as pin-holing and incomplete coverage. OAP coatings are widely used in various industries outside of bridge maintenance painting.  This study addressed the laboratory evaluation and field trial of an OAP coating for KYTC bridges. OAP coatings were evaluated for inspectability and accelerated weathering performance in a laboratory test program. After successful laboratory performance, OAP coatings were specified for a KYTC bridge painting project incorporating two deck-girder bridges. One bridge was coated with an OAP zinc urethane primer/non-OAP epoxy mid-coat/OAP urethane top-coat system. The second bridge was coated with a non-OAP zinc urethane primer/OPA epoxy mid-coat/non-OAP urethane top-coat. Field observations revealed that OAP coatings improved inspectability by making uncoated and thinly coated areas more readily identifiable.
Hamiltonian reductions in Matrix Painlevé systems
Creators: name: Bershtein, Mikhail
name: Grigorev, Andrei
name: Shchechkin, Anton
Publisher: name: arXiv
Year: 2022
Subjects: subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: For certain finite groups $G$ of Bäcklund transformations we show that the dynamics of $G$-invariant configurations of $n|G|$ Calogero--Painlevé particles is equivalent to certain $n$-particle Calogero--Painlevé system. We also show that the reduction of dynamics on $G$-invariant subset of $n|G|\times n|G|$ matrix Painlevé system is equivalent to certain $n\times n$ matrix Painlevé system. The groups $G$ correspond to folding transformations of Painlevé equations. The proofs are based on the Hamiltonian reductions.
description: 37 pages