cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Discriminating power of milli-lensing observations for dark matter models
Creators: name: Loudas, Nick
name: Pavlidou, Vasiliki
name: Casadio, Carolina
name: Tassis, Kostas
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The nature of dark matter (DM) is still under intense debate. Sub-galactic scales are particularly critical, as different, currently viable DM models make diverse predictions on the expected abundance and density profile of DM haloes on these scales. We investigate the ability of sub-galactic DM haloes to act as strong lenses on background compact sources, producing gravitational lensing events on milli-arcsecond scales (milli-lenses), for different DM models. For each DM scenario, we explore whether a sample of $\sim$ 5000 distant sources is sufficient to detect at least one milli-lens. We develop a semi-analytical model to estimate the milli-lensing optical depth as a function of the source's redshift for various DM models. We employ the Press-Schechter formalism, as well as results from recent N-body simulations to compute the halo mass function, taking into account the appropriate spherically averaged density profile of haloes for each DM model. We treat the lensing system as a point-mass lens and invoke the effective surface mass density threshold to calculate the fraction of a halo that acts as a gravitational lens. We study three classes of dark matter models: cold DM, warm DM, and self-interacting DM. We find that haloes consisting of warm DM turn out to be optically thin for strong gravitational milli-lensing (zero expected lensing events). CDM haloes may produce lensing events depending on the steepness of the concentration-mass relation. Self-interacting DM haloes can efficiently act as gravitational milli-lenses only if haloes experience gravothermal collapse, resulting in highly dense central cores.
description: 11 pages, 6 figures. Submitted for publication in A&A
Superradiant to subradiant phase transition in the open system Dicke model: Dark state cascades
Creators: name: Gegg, Michael
name: Carmele, Alexander
name: Knorr, Andreas
name: Richter, Marten
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Collectivity in ensembles of atoms gives rise to effects like super- and subradiance. While superradiance is well studied and experimentally accessible, subradiance remains elusive since it is difficult to track experimentally as well as theoretically. Here we present a new type of phase transition in the resonantly driven, open Dicke model that leads to a deterministic generation of subradiant states. At the transition the system switches from a predominantly superradiant to a predominantly subradiant state. Clear experimental signatures for the effect are presented and entanglement properties are discussed. Letting the system relax into the ground state generates a cascade of dark Dicke states, with dark state populations up to unity. Furthermore we introduce a collectivity measure that allows to quantify collective behavior.
Effects of an eccentric inner Jupiter on the dynamical evolution of icy body reservoirs in a planetary scattering scenario
Creators: name: Zanardi, M.
name: de Elía, G. C.
name: Di Sisto, R. P.
name: Naoz, S.
name: Li, G.
name: Guilera, O. M.
name: Brunini, A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We analyze the process of planetary scattering around M0-type stars. To do this, we carry out N-body simulations with three Jupiter-mass planets close to their instability limit together with an outer planetesimal disk. This paper focuses on the analysis of systems in which a single Jupiter-mass planet survives after the dynamical instability event. The small body reservoirs show different dynamical behaviors. In fact, our simulations produce particles on prograde and retrograde orbits, as well as particles whose orbital plane flips from prograde to retrograde and back again along their evolution. Such particles are called "Type-F particles". We find strong correlations between the inclination $i$ and the ascending node longitude $Ω$ of such particles. First, $Ω$ librates around 90$^{\circ}$ or/and 270$^{\circ}$. This property is very important since it represents a necessary and sufficient condition for the flipping of an orbit. Moreover, the libration periods of $i$ and $Ω$ are equal and they are out to phase by a quarter period. We also remark that the larger the libration amplitude of $i$, the larger the libration amplitude of $Ω$. Finally, we analyze the initial conditions of Type-F particles of all our simulations immediately after the dynamical instability event, when a single Jupiter-mass planet survives in the system. We carry out this study with the goal to determine the parameter space that lead to the flipping of an orbit. Our results suggest that the orbit of a test particle can flip for any value of its initial eccentricity, although we found only two Type-F particles with initial inclinations $i
description: 13 pages, 14 figures, Accepted for publication in Astronomy & Astrophysics
Fiducial, total and differential cross-section measurements of $t$-channel single top-quark production in $pp$ collisions at 8 TeV using data collected by the ATLAS detector
Creators: name: ATLAS Collaboration
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Detailed measurements of $t$-channel single top-quark production are presented. They use 20.2 fb$^{-1}$ of data collected by the ATLAS experiment in proton-proton collisions at a centre-of-mass energy of 8 TeV at the LHC. Total, fiducial and differential cross-sections are measured for both top-quark and top-antiquark production. The fiducial cross-section is measured with a precision of 5.8 % (top quark) and 7.8 % (top antiquark), respectively. The total cross-sections are measured to be $σ_{\mathrm{tot}}(tq) = 56.7^{+4.3}_{-3.8}\;$pb for top-quark production and $σ_{\mathrm{tot}}(\bar{t}q) = 32.9^{+3.0}_{-2.7}\;$pb for top-antiquark production, in agreement with the Standard Model prediction. In addition, the ratio of top-quark to top-antiquark production cross-sections is determined to be $R_t=1.72 \pm 0.09$, with an improved relative precision of 4.9 % since several systematic uncertainties cancel in the ratio. The differential cross-sections as a function of the transverse momentum and rapidity of both the top quark and the top antiquark are measured at both the parton and particle levels. The transverse momentum and rapidity differential cross-sections of the accompanying jet from the $t$-channel scattering are measured at particle level. All measurements are compared to various Monte Carlo predictions as well as to fixed-order QCD calculations where available.
description: 70 pages in total, author list starting on page 54, 22 figures, 21 tables, submitted to Eur. Phys. J. C. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2015-05/. This version matches publication
Interactivism in Spoken Dialogue Systems
Creators: name: Muñoz, T. Rodríguez
name: Ip, Emily Y. J.
name: Huang, G.
name: Moore, R. K.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computation and Language (cs.CL)
subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences
subject: H.1.2, H.5.2, I.2.11, J.4

description: The interactivism model introduces a dynamic approach to language, communication and cognition. In this work, we explore this fundamental theory in the context of dialogue modelling for spoken dialogue systems (SDS). To extend such a theoretical framework, we present a set of design principles which adhere to central psycholinguistic and communication theories to achieve interactivism in SDS. From these, key ideas are linked to constitute the basis of our proposed design principles.
Temporally versatile polarization entanglement from Bragg-reflection waveguides
Creators: name: Schlager, A.
name: Pressl, B.
name: Laiho, K.
name: Suchomel, H.
name: Kamp, M.
name: Höfling, S.
name: Schneider, C.
name: Weihs, G.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Bragg-reflection waveguides emitting broadband parametric down-conversion (PDC) have been proven to be well suited for the on-chip generation of polarization entanglement in a straightforward fashion [R. T. Horn et al., Sci. Rep. 3, 2314 (2013)]. Here, we investigate how the properties of the created states can be modified by controlling the relative temporal delay between the pair of photons created via PDC. Our results offer an easily accessible approach for changing the coherence of the polarization entanglement, in other words, to tune the phase of the off-diagonal elements of the density matrix. Furthermore, we provide valuable insight in the engineering of these states directly at the source.
description: 5 pages, 4 figures
Submissão SBIE 2023 - Artigo Interoperabilidade em LMSs: Uma Revisão Bibliométrica - Material Suplementar Etado da Arte
Creators: name: Silva, Jackson
Publisher: name: figshare
Year: 2023
Subjects: classificationCode: 390409
subject: Learning sciences
classificationCode: 461299
subject: Software engineering not elsewhere classified

description: Material suplementar para o artigo submetido ao SBIE 2023. Título: Interoperabilidade em LMSs: Uma Revisão Bibliométrica Contém: Base de dados, Script R e Planilha de avaliação manual dos artigos.
Star-forming early- and quiescent late-type galaxies in the local Universe
Creators: name: Paspaliaris, E. -D.
name: Xilouris, E. M.
name: Nersesian, A.
name: Bianchi, S.
name: Georgantopoulos, I.
name: Masoura, V. A.
name: Magdis, G. E.
name: Plionis, M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The general consensus is that LTGs undergo intense star-formation activity, while ETGs are mostly inactive. We question this general rule and investigate the existence of star-forming ETGs and quiescent LTGs in the local Universe. By computing the physical properties of 2,209 such galaxies in the GAMA survey being morphologically classified and using information on their structural properties as well as the density of their local environment, we seek for understanding the differences from their 'typical' counterparts. We separate galaxies into subsets based on their dominant ionising process, making use of criteria based on the WH$_α$ width and the [NII/H$_α$] ratio. Taking advantage of the SED fitting code CIGALE we derive galaxy properties, such as the $M_\text{star}$, $M_\text{dust}$, and SFR and also estimate the unattenuated and the dust-absorbed stellar emission, for both the young and old stellar populations. Ongoing star-formation activity is found in 47% of ETGs and 8% of LTGs are quiescent. The star-forming E galaxies, together with the LBSs, constitute a population that follows very well the SFMS of spiral galaxies. The fraction of the luminosity originating from young stars in the star-forming ETGs is quite substantial ($\sim$ 25%) and similar to that of the star-forming LTGs. Investigating possible differences between star-forming and quiescent galaxies we find that the intrinsic shape of the SED of the star-forming galaxies is, on average, very similar for all morphological types. Concerning their structural parameters, quiescent galaxies tend to show larger values of the Sérsic index and larger $R_\text{eff}$ (compared to star-forming galaxies). Finally, we find that star-forming galaxies preferably reside in lower-density environments compared to the quiescent ones, which exhibit a higher percentage of sources being members of groups.
Galilean contractions of $W$-algebras
Creators: name: Rasmussen, Jorgen
name: Raymond, Christopher
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Infinite-dimensional Galilean conformal algebras can be constructed by contracting pairs of symmetry algebras in conformal field theory, such as $W$-algebras. Known examples include contractions of pairs of the Virasoro algebra, its $N=1$ superconformal extension, or the $W_3$ algebra. Here, we introduce a contraction prescription of the corresponding operator-product algebras, or equivalently, a prescription for contracting tensor products of vertex algebras. With this, we work out the Galilean conformal algebras arising from contractions of $N=2$ and $N=4$ superconformal algebras as well as of the $W$-algebras $W(2,4)$, $W(2,6)$, $W_4$, and $W_5$. The latter results provide evidence for the existence of a whole new class of $W$-algebras which we call Galilean $W$-algebras. We also apply the contraction prescription to affine Lie algebras and find that the ensuing Galilean affine algebras admit a Sugawara construction. The corresponding central charge is level-independent and given by twice the dimension of the underlying finite-dimensional Lie algebra. Finally, applications of our results to the characterisation of structure constants in $W$-algebras are proposed.
description: 45 pages, v2: minor changes, references added
Maximal Masses of White Dwarfs for Polytropes in $R^2$ Gravity and Theoretical Constraints
Creators: name: Astashenok, Artyom V.
name: Odintsov, Sergey D.
name: Oikonomou, Vasilis K.
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We examine the Chandrasekhar limit for white dwarfs in $f(R)$ gravity, with a simple polytropic equation of state describing stellar matter. We use the most popular $f(R)$ gravity model, namely the $f(R)=R+αR^2$ gravity, and calculate the parameters of the stellar configurations with polytropic equation of state of the form $p=Kρ^{1+1/n}$ for various values of the parameter $n$. In order to simplify our analysis we use the equivalent Einstein frame form of $R^2$-gravity which is basically a scalar-tensor theory with well-known potential for the scalar field. In this description one can use simple approximations for the scalar field $ϕ$ leaving only the potential term for it. Our analysis indicates that for the non-relativistic case with $n=3/2$, discrepancies between the $R^2$-gravity and General Relativity can appear only when the parameter $α$ of the $R^2$ term, takes values close to maximal limit derived from the binary pulsar data namely $α_{max}=5\times 10^{15}$ cm$^2$. Thus, the study of low-mass white dwarfs can hardly give restrictions on the parameter $α$. For relativistic polytropes with $n=3$ we found that Chandrasekhar limit can in principle change for smaller $α$ values. The main conclusion from our calculations is the existence of white dwarfs with large masses $\sim 1.33 M_{\odot}$, which can impose more strict limits on the parameter $α$ for the $R^2$ gravity model. Specifically, our estimations on the parameter $α$ of the $R^2$ model is $α\sim 10^{13}$ cm$^2$.
description: 13 pp., 6 figures, to appear in Phys. Rev. D
New Window on Matter-Antimatter Differences
Creators: name: Zhou, Xiaorong
name: Olsen, Stephen Lars
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Recent measurements of $CP$-related comparisons of the weak-interaction parameters that describe the decays of the $Ξ^-$ and the $\barΞ^+$ doubly strange hyperon and antihyperon are reviewed and their significance is discussed.
Superflares on solar-like stars: A new method for identifying the true flare sources in photometric surveys
Creators: name: Vasilyev, Valeriy
name: Reinhold, Timo
name: Shapiro, Alexander I.
name: Krivova, Natalie A.
name: Usoskin, Ilya
name: Montet, Benjamin T.
name: Solanki, Sami K.
name: Gizon, Laurent
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Over the past years, thousands of stellar flares have been detected by harvesting data from large photometric surveys. These detections, however, do not account for potential sources of contamination such as background stars appearing in the same aperture as the primary target. We present a new method for identifying the true flare sources in large photometric surveys using data from the Kepler mission. Potential flares are identified in two steps: first, we search the light curves for at least two subsequent data points exceeding a 5σ threshold above the running mean. For these two cadences, we subtract the "quiet" stellar flux from the Kepler pixel data to obtain new images where the potential flare is the main light source. In the second step, we use a Bayesian approach to fit the point spread function of the instrument to determine the most likely location of the flux excess on the detector. We applied our method to 5862 main-sequence stars with near-solar effective temperatures. We found 2274 events exceeding the 5-sigma in at least two consecutive points in the light curves. Applying the second step reduced this number to 342 superflares. Of these, 283 flares happened on 178 target stars, 47 events are associated with fainter background stars, and in 10 cases, the flare location cannot be distinguished between the target and a background star. We also present cases where flares have been reported previously but our technique could not attribute them to the target star. We conclude that 1) identifying outliers in the light curves alone is insufficient to attribute them to stellar flares and 2) flares can only be uniquely attributed to a certain star when the instrument pixel-level data together with the point spread function are taken into account. As a consequence, previous flare statistics are likely contaminated by instrumental effects and unresolved astrophysical sources.
description: accepted for publication in Astronomy and Astrophysics
Chemistry and dynamics of the prestellar core L1544
Creators: name: Sipilä, O.
name: Caselli, P.
name: Redaelli, E.
name: Spezzano, S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We aim to quantify the effect of chemistry on the infall velocity in the prestellar core L1544. Previous observational studies have found evidence for double-peaked line profiles for the rotational transitions of several molecules, which cannot be accounted for with the models presently available for the physical structure of the source, without ad hoc up-scaling of the infall velocity. We ran one-dimensional hydrodynamical simulations of the collapse of a core with L1544-like properties (in terms of mass and outer radius), using a state-of-the-art chemical model with a very large chemical network combined with an extensive description of molecular line cooling, determined via radiative transfer simulations, with the aim of determining whether these expansions of the simulation setup (as compared to previous models) can lead to a higher infall velocity. After running a series of simulations where the simulation was sequentially simplified, we found that the infall velocity is almost independent of the size of the chemical network or the approach to line cooling. We conclude that chemical evolution does not have a large impact on the infall velocity, and that the higher infall velocities that are implied by observations may be the result of the core being more dynamically evolved than what is now thought, or alternatively the average density in the simulated core is too low. However, chemistry does have a large influence on the lifetime of the core, which varies by about a factor of two across the simulations and grows longer when the chemical network is simplified. Therefore, although the model is subject to several sources of uncertainties, the present results clearly indicate that the use of a small chemical network leads to an incorrect estimate of the core lifetime, which is naturally a critical parameter for the development of chemical complexity in the precollapse phase.
description: 12 pages incl. Appendix; 8 figures; accepted to A&A; replacement to reflect the change of the title of the paper post-acceptance
Determination of $α_s(m_Z)$ by the non-perturbative decoupling method
Creators: name: Brida, Mattia Dalla
name: Höllwieser, Roman
name: Knechtli, Francesco
name: Korzec, Tomasz
name: Nada, Alessandro
name: Ramos, Alberto
name: Sint, Stefan
name: Sommer, Rainer
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We present the details and first results of a new strategy for the determination of $α_s(m_Z)$. By simultaneously decoupling 3 fictitious heavy quarks we establish a relation between the $Λ$-parameters of three-flavor QCD and pure gauge theory. Very precise recent results in the pure gauge theory can thus be leveraged to obtain the three-flavour $Λ$-parameter in units of a common decoupling scale. Connecting this scale to hadronic physics in 3-flavour QCD leads to our result in physical units, $Λ^{(3)}_{\bar{\rm MS}} = 336(12)\, {\rm MeV}$, which translates to $α_s(m_Z) = 0.11823(84)$. This is compatible with both the FLAG average and the previous ALPHA result, with a comparable, yet still statistics dominated, error. This constitutes a highly non-trivial check, as the decoupling strategy is conceptually very different from the 3-flavour QCD step-scaling method, and so are their systematic errors. These include the uncertainties of the combined decoupling and continuum limits, which we discuss in some detail. We also quantify the correlation between both results, due to some common elements, such as the scale determination in physical units and the definition of the energy scale where we apply decoupling.
description: 62 pages, 10 figures, LaTeX
Are Am stars and hot-Jupiter planets related?
Creators: name: Saffe, C.
name: Alacoria, J.
name: Miquelarena, P.
name: Petrucci, R.
name: Arancibia, M. Jaque
name: Angeloni, R.
name: Martioli, E.
name: Flores, M.
name: Jofre, E.
name: Collado, A.
name: Gunella, F.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Am stars are often components of short-period binary systems, where tidal interactions would result in low rotational velocities and help to develop the chemical peculiarities observed. However, the origin of single Am stars and Am stars that belong to wide binary systems is unclear. There is very recent evidence of an Am star hosting a hot-brown dwarf likely synchronized and other possible Am stars hosting hot-Jupiter planets. We wonder if these hot-low mass companions could play a role in the development of an Am star, that is to say, if they could help to mitigate the "single Am" problem. We studied a sample of 19 early-type stars, 7 of them hosting hot-brown dwarfs and 12 of them hosting hot-Jupiter planets. We detected 4 Am stars in our sample (KELT-19A, KELT-17, HATS-70 and TOI-503) and 2 possible Am stars (TOI-681 and HAT-P-69). In particular, we detected the new Am star HATS-70 which hosts a hot-brown dwarf, and rule out this class for the hot-Jupiter host WASP-189, both showing different composition than previously reported. We estimated the incidence of Am stars within stars hosting hot-brown dwarfs (50-75%) and within stars hosting hot-Jupiters (20-42%). The incidence of Am stars hosting hot-brown dwarfs resulted higher than the frequency of Am stars in general. This would imply that the presence of hot-brown dwarfs could play a role in the development of Am stars and possibly help to mitigate the "single Am" problem, different to the case of hot-Jupiter planets. Notably, these results would also indicate that the search for hot-brown dwarfs may be benefited by targeting single Am stars or Am stars in wide binary systems. We encourage the analysis off additional early-type stars hosting hot-companions in order to improve the significance of the initial trends found here. [abridged]
description: 15 pages, 10 figures, 3 tables (11 tables in the Appendix), A&A accepted
title: Time-dependent model for sand grain deflection including contact maturing under sustained load
title: none
titleType: AlternativeTitle
Creators: name: Michalowski, Radoslaw
Publisher: name: Springer
Year: 2020
Subjects: subject: NSF-1901582
subject: Civil and Environmental Engineering
subject: Engineering

description: -
description: The hypothesis of contact maturing advocates static fatigue at contacts between sand grains as the key cause contributing to time effects in sand. The focus of the paper is on a model of an individual grain subjected to a sustained load applied through two steel plates. The grain is characterized by the roughness of its surface. The distinct element method is used to construct a model on two scales: the grain scale and the contact scale. Assemblies of bonded sub-particles are used to model both the grain and the contact region. The bond model includes the stress corrosion process, which simulates decaying strength of bonds and fracture. Two components of the time-dependent grain deflection under sustained loads are the displacement owed to sub-critical fracturing of asperities on the grain surface at the contacts and the creep of the core mineral in the grain. The model demonstrates what may be difficult capturing in physical testing. The simulated nominal contact evolves as the number of contact points increases due to sub-critical fracturing of asperities, leaving the contact firmer. The contact evolution process, as observed in simulations, is consistent with the contact maturing hypothesis.
NuSTAR spectral analysis beyond 79 keV with stray light
Creators: name: Mastroserio, G.
name: Grefenstette, B. W.
name: Thalhammer, P.
name: Buisson, D. J. K.
name: Brumback, M. C.
name: Ludlam, R. M.
name: Connors, R. M. T.
name: Garcıa, J. A.
name: Grinberg, V.
name: Madsen, K. K.
name: Miyasaka, H.
name: Tomsick, J. A.
name: Wilms, J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Due to the structure of the NuSTAR telescope, photons at large off-axis (> 1deg) can reach the detectors directly (stray light), without passing through the instrument optics. At these off-axis angles NuSTAR essentially turns into a collimated instrument and the spectrum can extend to energies above the Pt k-edge (79 keV) of the multi-layers, which limits the effective area bandpass of the optics. We present the first scientific spectral analysis beyond 79 keV using a Cygnus X-1 observation in StrayCats, the catalog of stray light observations. This serendipitous stray light observation occurred simultaneously with an INTEGRAL observation. When the spectra are modeled together in the 30-120 keV energy band, we find that the NuSTAR stray light flux is well calibrated and constrained to be consistent with the INTEGRAL flux at the 90% confidence level. Furthermore, we explain how to treat the background of the stray light spectral analysis, which is especially important at high energies.
description: Accepted for publication in ApJ
Image reconstruction from radially incomplete spherical Radon data
Creators: name: Ambartsoumian, Gaik
name: Gouia-Zarrad, Rim
name: Krishnan, Venkateswaran P.
name: Roy, Souvik
Publisher: name: arXiv
Year: 2017
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Analysis of PDEs (math.AP)
subject: Numerical Analysis (math.NA)
subject: Spectral Theory (math.SP)
subject: FOS: Mathematics

description: We study inversion of the spherical Radon transform with centers on a sphere (the data acquisition set). Such inversions are essential in various image reconstruction problems arising in medical, radar and sonar imaging. In the case of radially incomplete data, we show that the spherical Radon transform can be uniquely inverted recovering the image function in spherical shells. Our result is valid when the support of the image function is inside the data acquisition sphere, outside that sphere, as well as on both sides of the sphere. Furthermore, in addition to the uniqueness result our method of proof provides reconstruction formulas for all those cases. We present a robust computational algorithm based on our inversion formula and demonstrate its accuracy and efficiency on several numerical examples.
Three major reasons why transgenerational effects of radiation are difficult to detect in humans
Creators: name: Nakamura, Nori
name: Yoshida, Noriaki
name: Suwa, Tatsuya
Publisher: name: Taylor & Francis
Year: 2023
Subjects: subject: Medicine
subject: Cell Biology
subject: Genetics
subject: FOS: Biological sciences
subject: Molecular Biology
subject: Pharmacology
subject: Biotechnology
subject: Evolutionary Biology
subject: Developmental Biology
subject: Cancer
subject: Virology

description: Ionizing radiation can induce mutations in germ cells in various organisms, including fruit flies and mice. However, currently, there is no clear evidence for the transgenerational effects of radiation in humans. This review is an effort to identify possible reasons for the lack of such observations. Literature search and narrative review. 1) In both mice and humans, resting oocytes locate primarily in the cortical region of the ovary where the number of blood vessels is very low especially when young and extra-cellular material is rich, and this region is consequently hypoxic, which probably leads to immature oocytes being resistant to the cell killing and mutagenic effects of radiation. 2) In studies of spermatogonia, the mouse genes used for specific locus test (SLT) studies, which include coat color genes, were hypermutable when compared to many other genes. Recent studies which examined over 1000 segments of genomic DNA indicate that the induction rate of deletion mutation per segment was on the order of 10−6 per Gy, which is one order of magnitude lower than that obtained from the SLT data. Therefore, it appears possible that detecting any transgenerational effects of radiation following human male exposures will be difficult due to a lack of mutable marker genes. 3) Fetal malformations were examined in studies in humans, but the genetic component in such malformations is low, and abnormal fetuses are prone to undergo miscarriage which does not occur in mice, and which leads to difficulties in detecting transgenerational effects. The lack of clear evidence for radiation effects in humans probably does not result from any problem in the methodologies used but may be due largely to biological properties. Currently, whole genome sequencing studies of exposed parents and offspring are planned, but ethical guidelines need to be followed to avoid discrimination, which had once happened to the atomic bomb survivors.
Paraxial forward-scatter field analysis for a THz pulse traveling down a highly overmoded iris-line waveguide
Creators: name: Naji, Adham
name: Stupakov, Gennady
Publisher: name: arXiv
Year: 2022
Subjects: subject: Accelerator Physics (physics.acc-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Highly overmoded iris-line structures carry desirable features for the efficient transportation of THz radiation over long distances. Previous studies have analyzed the iris line, modeled approximately as a long open-resonator structure with thin screens, using methods such as Vainstein's impedance boundary condition or perturbative mode matching. The aim in those methods was to seek the eigensolution that represents the dominant (least lossy) propagation mode in a long iris-line structure at steady state. In this paper, a forward-traveling wave analysis is presented, wherein a short THz pulse paraxially traverses the oversized structure cell by cell, including the transient regime. The iris line's periodic discontinuities are analyzed in terms of forward-wave orthogonal mode decompositions, which are then used to build a 'forward-scatter' model (matrix) for each cell. The presented approach predicts a diffraction loss behavior that agrees with that of the eigensolution found by the previous analytical methods at the steady state for a long waveguide, but adds the ability of analyzing waveguides of finite lengths, showing transients as they evolve and settle to the dominant mode down the line, and offers numerical implementation speeds that are typically an order-of-magnitude faster than those previously reported for the mode-matching method. This approach may also be easily extended to analyze iris lines with mechanical imperfections (e.g. misalignments or aperiodic defects), allowing for investigations of performance sensitivity against manufacturing tolerances.
description: 22 pages, 13 figures. [Version 2: corrected some typos and updated some figures to remove phase from transient curves (magnitude)]
Consideration of hereditary effects in the radiological protection system: evolution and current status
Creators: name: Amrenova, A.
name: Ainsbury, E.
name: Baudin, C.
name: Giussani, A.
name: Lochard, J.
name: Rühm, W.
name: Scholz-Kreisel, P.
name: Trott, K.
name: Vaillant, L.
name: Wakeford, R.
name: Zölzer, F.
name: Laurier, D.
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Medicine
subject: Genetics
subject: FOS: Biological sciences
subject: Sociology
subject: FOS: Sociology
subject: Biological Sciences not elsewhere classified
subject: Cancer
subject: Science Policy

description: The purpose of this paper is to provide an overview of the methodology used to estimate radiation genetic risks and quantify the risk of hereditary effects as outlined in the ICRP Publication 103. It aims to highlight the historical background and development of the doubling dose method for estimating radiation-related genetic risks and its continued use in radiological protection frameworks. This article emphasizes the complexity associated with quantifying the risk of hereditary effects caused by radiation exposure and highlights the need for further clarification and explanation of the calculation method. As scientific knowledge in radiation sciences and human genetics continues to advance in relation to a number of factors including stability of disease frequency, selection pressures, and epigenetic changes, the characterization and quantification of genetic effects still remains a major issue for the radiological protection system of the International Commission on Radiological Protection. Further research and advancements in this field are crucial for enhancing our understanding and addressing the complexities involved in assessing and managing the risks associated with hereditary effects of radiation.
Towards measuring supermassive black hole masses with interferometric observations of the dust continuum
Creators: name: GRAVITY Collaboration
name: Amorim, A.
name: Bourdarot, G.
name: Brandner, W.
name: Cao, Y.
name: Clénet, Y.
name: Davies, R.
name: de Zeeuw, P. T.
name: Dexter, J.
name: Drescher, A.
name: Eckart, A.
name: Eisenhauer, F.
name: Fabricius, M.
name: Schreiber, N. M. Förster
name: Garcia, P. J. V.
name: Genzel, R.
name: Gillessen, S.
name: Gratadour, D.
name: Hönig, S.
name: Kishimoto, M.
name: Lacour, S.
name: Lutz, D.
name: Millour, F.
name: Netzer, H.
name: Ott, T.
name: Paumard, T.
name: Perraut, K.
name: Perrin, G.
name: Peterson, B. M.
name: Petrucci, P. O.
name: Pfuhl, O.
name: Prieto, M. A.
name: Rouan, D.
name: Santos, D. J. D.
name: Shangguan, J.
name: Shimizu, T.
name: Sternberg, A.
name: Straubmeier, C.
name: Sturm, E.
name: Tacconi, L. J.
name: Tristram, K. R. W.
name: Widmann, F.
name: Woillez, J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: This work focuses on active galactic nuclei (AGNs), and the relation between the sizes of the hot dust continuum and the broad-line region (BLR). We find that the continuum size measured using optical/near-infrared interferometry (OI) is roughly twice that measured by reverberation mapping (RM). Both OI and RM continuum sizes show a tight relation with the H$β$ BLR size with only an intrinsic scatter of 0.25 dex. The masses of supermassive black holes (BHs) can hence be simply derived from a dust size in combination with a broad line width and virial factor. Since the primary uncertainty of these BH masses comes from the virial factor, the accuracy of the continuum-based BH masses is close to those based on the RM measurement of the broad emission line. Moreover, the necessary continuum measurements can be obtained on a much shorter timescale than those required monitoring for RM, and are also more time efficient than those needed to resolve the BLR with OI. The primary goal of this work is to demonstrate measuring the BH mass based on the dust continuum size with our first calibration of the $R_\mathrm{BLR}$-$R_\mathrm{d}$ relation. The current limitation and caveats are discussed in detail. Future GRAVITY observations are expected to improve the continuum-based method and have the potential to measure BH masses for a large sample of AGNs in the low-redshift Universe.
description: Accepted for publication in A&A; 11 pages, 5 figures, 3 tables
q-Path entropy phenomenology for phase-space curves
Creators: name: Zamora, D. J.
name: Rocca, M. C.
name: Plastino, A.
name: Ferri, G. L.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We describe the phenomenology of the classical q-path entropy of a phase-space curve. This allows one to disclose an entropic force-like mechanism that is able to mimic some phenomenological aspects of the strong force, such as confinement, hard core, and asymptotic freedom.
description: 18 pages, 4 figures Title has changed. Text has changed
Helium-bearing superconductor at high pressure
Creators: name: Hou, Jingyu
name: Dong, Xiao
name: Oganov, Artem R.
name: Weng, Xiao-Ji
name: Hao, Chun-Mei
name: Yang, Guochun
name: Wang, Hui-Tian
name: Zhou, Xiang-Feng
name: Tian, Yongjun
Publisher: name: arXiv
Year: 2022
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Helium (He) is the most inert noble gas at ambient conditions. It adopts a hexagonal close packed structure (P63/mmc) and remains in the insulating phase up to 32 TPa. In contrast, lithium (Li) is one of the most reactive metals at zero pressure, while its cubic high-pressure phase (Fd-3m) is a weak metallic electride above 475 GPa. Strikingly, a stable compound of Li5He2 (R-3m) was formed by mixing Fd-3m Li with P63/mmc He above 700 GPa. The presence of helium promotes the lattice transformation from Fd-3m Li to Pm-3m Li, and tuns the three-dimensional distributed interstitial electrons into the mixture of zero- and two-dimensional anionic electrons. This significantly increases the degree of metallization at the Fermi level, consequently, the coupling of conductive anionic electrons with the Li-dominated vibrations is the key factor to the formation of superconducting electride Li5He2 with a transition temperature up to 26 K, dynamically stable to pressures down to 210 GPa.
description: 5 pages, 3 figures
Spatial Random Sampling: A Structure-Preserving Data Sketching Tool
Creators: name: Rahmani, Mostafa
name: Atia, George
Publisher: name: arXiv
Year: 2017
Subjects: subject: Machine Learning (cs.LG)
subject: Methodology (stat.ME)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: Random column sampling is not guaranteed to yield data sketches that preserve the underlying structures of the data and may not sample sufficiently from less-populated data clusters. Also, adaptive sampling can often provide accurate low rank approximations, yet may fall short of producing descriptive data sketches, especially when the cluster centers are linearly dependent. Motivated by that, this paper introduces a novel randomized column sampling tool dubbed Spatial Random Sampling (SRS), in which data points are sampled based on their proximity to randomly sampled points on the unit sphere. The most compelling feature of SRS is that the corresponding probability of sampling from a given data cluster is proportional to the surface area the cluster occupies on the unit sphere, independently from the size of the cluster population. Although it is fully randomized, SRS is shown to provide descriptive and balanced data representations. The proposed idea addresses a pressing need in data science and holds potential to inspire many novel approaches for analysis of big data.
Direct numerical simulation of compressible turbulence accelerated by graphics processing unit. Part 1: An open-source high accuracy accelerated computational fluid dynamic software
Creators: name: Dang, Guanlin
name: Liu, Shiwei
name: Guo, Tongbiao
name: Duan, Junyi
name: Li, Xinliang
Publisher: name: arXiv
Year: 2022
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: This paper introduces open-source computational fluid dynamics software named open computational fluid dynamic code for scientific computation with graphics processing unit (GPU) system (OpenCFD-SCU), developed by the authors for direct numerical simulation (DNS) of compressible wall-bounded turbulence. This software is based on the finite difference method and is accelerated by the use of a GPU, which provides an acceleration by a factor of more than 200 compared with central processing unit (CPU) software based on the same algorithm and number of message passing interface (MPI) processes, and the running speed of OpenCFD-SCU with just 512 GPUs exceed that of CPU software with 130\,000 CPUs. GPU-Stream technology is used to implement overlap of computing and communication, achieving 98.7\% parallel weak scalability with 24\,576 GPUs. The software includes a variety of high-precision finite difference schemes, and supports a hybrid finite difference scheme, enabling it to provide both robustness and high precision when simulating complex supersonic and hypersonic flows. When used with the wide range of supercomputers currently available, the software should able to improve the performance of large-scale simulations by up to two orders on the computational scale. Then, OpenCFD-SCU is applied to a validation and verification case of a Mach 2.9 compression ramp with mesh numbers up to 31.2 billion. More challenging cases using hybrid finite schemes are shown in Part 2(Dang, Li et al. 2022). The code is available and supported at \url{http://developer.hpccube.com/codes/danggl/opencfd-scu.git}.
description: 23 pages, 25 figures
Improved Pulse Shape Discrimination in EJ-301 liquid scintillators
Creators: name: Lang, R. F.
name: Masson, D.
name: Pienaar, J.
name: Röttger, S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: High Energy Physics - Experiment (hep-ex)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Digital pulse shape discrimination has become readily available to distinguish nuclear recoil and electronic recoil events in scintillation detectors. We evaluate digital implementations of pulse shape discrimination algorithms discussed in the literature, namely the Charge Comparison Method, Pulse-Gradient Analysis, Fourier Series and Standard Event fitting. In addition, we present a novel algorithm based on a Laplace Transform. Instead of reducing the performance of these algorithms to a single Figure of Merit, we evaluate them as function of recoil energy. Specifically, using commercial EJ-301 liquid sctintillators, we examine both the resulting acceptance of nuclear recoils at a given rejection level of electronic recoils, as well as the purity of the selected nuclear recoil event samples. We find that both a Standard Event fit and a Laplace Transform can be used to significantly improve the discrimination capabilities over the whole energy range. Furthermore, we show that the Charge Comparison Method performs poorly in accurately identifying nuclear recoils.
description: 8 pages, 8 figures
A systematic review of human evidence for the intergenerational effects of exposure to ionizing radiation
Creators: name: Stephens, Jade
name: Moorhouse, Alexander J.
name: Craenen, Kai
name: Schroeder, Ewald
name: Drenos, Fotios
name: Anderson, Rhona
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Medicine
subject: Pharmacology
subject: Biotechnology
subject: Sociology
subject: FOS: Sociology
subject: Science Policy

description: To provide a synthesis of the published evidence pertaining to the intergenerational health effects of parental preconceptional exposure to ionizing radiation in humans. The study populations are the descendants of those who were exposed to ionizing radiation prior to conception. A Boolean search identified publications for review in accordance with Office of Health Assessment and Translation guidelines. Initially, a risk of bias assessment was conducted for each published study and relevant data extracted. Information was organized into adverse health outcome groups and exposure situations. To make an assessment from the body of evidence within each group, an initial confidence rating was assigned, before factors including inconsistencies between studies, magnitude of effect, dose response and confounders were considered. From this, ‘an effect’, ‘no effect’ or whether the evidence remained ‘inadequate’ to determine either effect or no effect, was ascertained. This assessment was based primarily upon the author’s conclusions within that evidence-base and, by binomial probability testing of the direction of effect reported. 2441 publications were identified for review which after screening was reduced to 127. For the majority of the adverse health groups, we find there to be inadequate evidence from which to determine whether the health effect was, or was not, associated with parental preconceptional radiation exposure. This was largely due to heterogeneity between individual study’s findings and conclusions within each group and, the limited number of studies within each group. We did observe one health grouping (congenital abnormalities) in occupationally exposed populations, where an increase in effect relative to their controls or large magnitude of effects, were reported, although it is noted that the authors of these studies interpreted their findings as most likely not to be associated with parental radiation exposure. We find there to be a lack of evidence to enable the formal assessment of radiation-related adverse effects in offspring of exposed humans. This is not the same as there being no clear evidence that effects may occur but does infer that if adverse health effects do arise in children of exposed parents, then these effects are small and difficult to reproducibly measure. Inconsistencies in designing studies are unavoidable, however we highlight the need for an element of standardization and, more sharing of primary datasets as part of open access initiatives, in order for future reviews to make reasonable conclusions. Overall, there is a need for future work to ensure comparable measures between studies where possible.