cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Time-warping invariants of multidimensional time series
Creators: name: Diehl, Joscha
name: Kurusch, Ebrahimi-Fard
name: Tapia, Nikolas
Publisher: name: Weierstrass Institute
Year: 2019
Subjects: subject: Time series analysis
subject: time-warping invariants
subject: signature
subject: quasisymmetric functions
subject: quasi-shuffle product
subject: Hoffman's exponential
subject: area-operation
subject: Hopf algebra
subject: 16T05
subject: 68T10
subject: 62H30
subject: 68Q10

description: In data science, one is often confronted with a time series representing measurements of some quantity of interest. Usually, in a first step, features of the time series need to be extracted. These are numerical quantities that aim to succinctly describe the data and to dampen the influence of noise. In some applications, these features are also required to satisfy some invariance properties. In this paper, we concentrate on time-warping invariants.We show that these correspond to a certain family of iterated sums of the increments of the time series, known as quasisymmetric functions in the mathematics literature. We present these invariant features in an algebraic framework, and we develop some of their basic properties.
CO(1-0), CO(2-1) and Neutral Gas in NGC 6946: Molecular Gas in a Late-Type, Gas Rich, Spiral Galaxy
Creators: name: Crosthwaite, Lucian
name: Turner, Jean
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present "On The Fly" maps of the CO(1-0) and CO(2-1) emission covering a 10' X 10' region of the NGC 6946. Using our CO maps and archival VLA HI observations we create a total gas surface density map, Sigma_gas, for NGC 6946. The predominantly molecular inner gas disk transitions smoothly into an atomic outer gas disk, with equivalent atomic and molecular gas surface densities at R = 3.5' (6 kpc). We estimate that the total H2 mass is 3 X 10^9 Mo, roughly 1/3 of the interstellar hydrogen gas mass, and about 2% of the dynamical mass of the galaxy at our assumed distance of 6 Mpc. The value of the CO(2-1)/CO(1-0) line ratio ranges from 0.35 to 2; 50% of the map is covered by very high ratio, >1, gas. The very high ratios are predominantly from interarm regions and appear to indicate the presence of wide-spread optically thin gas. Star formation tracers are better correlated with the total neutral gas disk than with the molecular gas by itself implying SFR is proportional to Sigma_gas. Using the 100 FIR and 21 cm continuum from NGC 6946 as star formation tracers, we arrive at a gas consumption timescale of 2.8 Gyr, which is relatively uniform across the disk. The high star formation rate at the nucleus appears to be due to a large accumulation of molecular gas rather than a large increase in the star formation efficiency. The mid-plane gas pressure in the outer (R > 10 kpc) HI arms of NGC 6946 is close to the value at the radial limit (10 kpc) of our observed CO disk. If the mid-plane gas pressure is a factor for the formation of molecular clouds, these outer HI gas arms should contain molecular gas which we do not see because they are beyond our detection limit.
First-principles computational methods for quantum defects in two-dimensional materials: A perspective
Creators: name: Seo, Hosung
name: Ivády, Viktor
name: Ping, Yuan
Publisher: name: arXiv
Year: 2024
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum defects are atomic defects in materials that provide resources to construct quantum information devices such as single-photon emitters (SPEs) and spin qubits. Recently, two-dimensional (2D) materials gained prominence as a host of quantum defects with many attractive features derived from their atomically thin and layered material formfactor. In this perspective, we discuss first-principles computational methods and challenges to predict the spin and electronic properties of quantum defects in 2D materials. We focus on the open quantum system nature of the defects and their interaction with external parameters such as electric field, magnetic field, and lattice strain. We also discuss how such prediction and understanding can be used to guide experimental studies, ranging from defect identification to tuning of their spin and optical properties. This perspective provides significant insights into the interplay between the defect, the host material, and the environment, which will be essential in the pursuit of ideal two-dimensional quantum defect platforms.
description: 37 pages, 5 figures. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 125, 140501 (2024) and may be found at https://doi.org/10.1063/5.0230736
Holographic Nuclear Matter in AdS/QCD
Creators: name: Kim, Youngman
name: Lee, Chang-Hwan
name: Yee, Ho-Ung
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We study the physics with finite nuclear density in the framework of AdS/QCD with holographic baryon field included. Based on a mean field type approach, we introduce the nucleon density as a bi-fermion condensate of the lowest mode of the baryon field and calculate the density dependence of the chiral condensate and the nucleon mass. We observe that the chiral condensate as well as the mass of nucleon decrease with increasing nuclear density. We also consider the mass splitting of charged vector mesons in iso-spin asymmetric nuclear matter.
description: 16 pages, 3 figures, two references are added, typo corrected, section 3.3 removed
Mechanism of acidification of expired water in fish
Creators: name: Lin, Hong
Publisher: name: University of British Columbia
Year: 2010

description: The effect of varying inhaled water pH on the acidification or alkalization of water as it passes over the gills in rainbow trout (Salmo gairdneri) was investigated by exposing the fish to pH 9.91 and pH 3.88 water. In the control and high pH treatment, water was acidified as it flowed over the gills of the fish because of the dominant effect of CO₂ hydration. Water was alkalized as it flowed over the gills of the fish in the low pH treatment due to NH₄⁺ formation and perhaps HCO₃₋ dehydration. The overall result of CO₂ and NH₃ excretion is to ameliorate the change of expired water pH in the face of changes in pH of inspired water. Carbon dioxide excretion was not significantly affected by the high or low pH treatments but ammonia was accumulated in fish plasma in both cases. The impact of Na⁺/H⁺ (NH₄⁺) and Cl⁻/HCO₃₋ exchange processes on the acidification or alkalization of expired water has also been examined. Amiloride or SITS was introduced to the water to inhibit the ionic exchange processes and environmental water pH was gradually lowered from neutral to acidic. Under acidic conditions, molecular CO₂ and NH₃ excretion alone could account for all the proton concentration changes from inspired to expired water, indicating that Na⁺/H⁺(NH₄⁺) transport was inhibited by low environmental pH. In neutral environments, the proton concentration changes were the result of molecular CCh and NH3 excretion, and sodium influx in exchange for H⁺(NH₄⁺). Cl⁻/HCO₃₋ exchange was not an important pathway for carbon dioxide elimination but inhibition of Na⁺/H⁺(NH₄⁺) exchange caused a reduction of ammonia excretion.
Entanglement dynamics for Unruh-DeWitt detectors interacting with massive scalar fields: The Unruh and anti-Unruh effects
Creators: name: Zhou, Yuebing
name: Hu, Jiawei
name: Yu, Hongwei
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study, in the framework of open quantum systems, the entanglement dynamics for a quantum system composed of two uniformly accelerated Unruh-Dewitt detectors interacting with a bath of massive scalar fields in the Minkowski vacuum. We find that the entanglement evolution for the quantum system coupled with massive fields is always slower compared with that of the one coupled with massless fields, and this time-delay effect brought by the field being massive can however be counteracted by a large enough acceleration, in contrast to the case of a static quantum system in a thermal bath, where this time delay is not affected by the temperature. Remarkably, the maximal concurrence of the quantum system generated during evolution may increase with acceleration for any inter-detector separation while that for static ones in a thermal bath decreases monotonically with temperature, and this can be considered as an anti-Unruh effect in terms of the entanglement generated.
description: 37 pages, 12 figures, published version
Quantum gas magnifier for sub-lattice-resolved imaging of three-dimensional quantum systems
Creators: name: Asteria, Luca
name: Zahn, Henrik P.
name: Kosch, Marcel N.
name: Sengstock, Klaus
name: Weitenberg, Christof
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Imaging is central for gaining microscopic insight into physical systems, but direct imaging of ultracold atoms in optical lattices as modern quantum simulation platform suffers from the diffraction limit as well as high optical density and small depth of focus. We introduce a novel approach to imaging of quantum many-body systems using matter wave optics to magnify the density distribution prior to optical imaging, allowing sub-lattice spacing resolution in three-dimensional systems. Combining the site-resolved imaging with magnetic resonance techniques for local addressing of individual lattice sites, we demonstrate full accessibility to local information and local manipulation in three-dimensional optical lattice systems. The method opens the path for spatially resolved studies of new quantum many-body regimes including exotic lattice geometries.
description: 5 pages, 4 figures, 12 pages of Supplementary Material
High Mobility in LaAlO3/SrTiO3 Heterostructures: Origin, Dimensionality and Perspectives
Creators: name: Herranz, G.
name: Basletic, M.
name: Bibes, M.
name: Carretero, C.
name: Tafra, E.
name: Jacquet, E.
name: Bouzehouane, K.
name: Deranlot, C.
name: Hamzic, A.
name: Broto, J. -M.
name: Barthelemy, A.
name: Fert, A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We have investigated the dimensionality and origin of the magnetotransport properties of LaAlO3 films epitaxially grown on TiO2-terminated SrTiO3(001) substrates. High mobility conduction is observed at low deposition oxygen pressures (PO2 < 10^-5 mbar) and has a three-dimensional character. However, at higher PO2 the conduction is dramatically suppressed and nonmetallic behavior appears. Experimental data strongly support an interpretation of these properties based on the creation of oxygen vacancies in the SrTiO3 substrates during the growth of the LaAlO3 layer. When grown on SrTiO3 substrates at low PO2, other oxides generate the same high mobility as LaAlO3 films. This opens interesting prospects for all-oxide electronics.
description: 4 pages, 4 figures. Accepted for publication in Phys. Rev. Lett
On the vierbein formalism of general relativity
Creators: name: Mei, T.
Publisher: name: arXiv
Year: 2007
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Both the Einstein-Hilbert action and the Einstein equations are discussed under the absolute vierbein formalism. Taking advantage of this form, we prove that the "kinetic energy" term, i.e., the quadratic term of time derivative term, in the Lagrangian of the Einstein-Hilbert action is non-positive definitive. And then, we present two groups of coordinate conditions that lead to positive definitive kinetic energy term in the Lagrangian, as well as the corresponding actions with positive definitive kinetic energy term, respectively. Based on the ADM decomposition, the Hamiltonian representation and canonical quantization of general relativity taking advantage of the actions with positive definitive kinetic energy term are discussed; especially, the Hamiltonian constraints with positive definitive kinetic energy term are given, respectively. Finally, we present a group of gauge conditions such that there is not any second time derivative term in the ten Einstein equations.
description: 29 pages, no figure. The previous three versions and fifth version of this paper has been withdrawn by the author due to some unclear discussion and errors
Quelques plats pour la métrique de Hofer
Creators: name: Py, Pierre
Publisher: name: arXiv
Year: 2007
Subjects: subject: Differential Geometry (math.DG)
subject: Group Theory (math.GR)
subject: Geometric Topology (math.GT)
subject: Symplectic Geometry (math.SG)
subject: FOS: Mathematics
subject: 53D05, 37J05, 20F65

description: We show, by an elementary and explicit construction, that the group of Hamiltonian diffeomorphisms of certain symplectic manifolds, endowed with Hofer's metric, contains subgroups quasi-isometric to Euclidean spaces of arbitrary dimension.
description: 9 pages, minor changes
Observations of B335 in the Millimeter Continuum and the 226 GHz H2CO Line
Creators: name: Choi, Minho
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The protostar B335 was observed in the 1.3 mm continuum and in the H2CO 312 - 211 line with an angular resolution of about 8 arcsec. The mass of the inner envelope detected by the dust continuum emission is about 0.02 Msun. The H2CO spectrum at the protostellar position shows a blue-skewed double peak profile, suggesting that the kinematics of the inner envelope is dominated by infall motion. When the blueshifted and the redshifted peaks were imaged separately, however, there is a small east-west displacement between the maximum positions. This displacement suggests that some part of the H2CO emission might come from the outflowing gas. A combined effect of the infalling envelope and the outflow on the radiative transfer is discussed. This effect can make the line profile asymmetry severer than what is expected from infall-only models.
(:unav)
Creators: name: (:Unav)
Publisher: name: Komitet Słowianoznawstwa PAN
Year: 2020

description: Rocznik Slawistyczny – ukazuje się od 1908 roku, początkowo w Krakowie, a od 1994 we Wrocławiu. Publikacje dotyczą szeroko pojętej slawistyki. Oprócz języka polskiego publikuje też artykuły w językach obcych.
Induced Quantized Spin Current in Vacuum
Creators: name: Chu, Chong-Sun
name: Leung, Chun-Hei
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Other Condensed Matter (cond-mat.other)
subject: High Energy Physics - Experiment (hep-ex)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We uncover a fundamental effect of the QED vacuum in an external electromagnetic (EM) field. We show that the quantized vacuum of electrons is spin polarized by the EM field and manifests as a vacuum spin current. An experiment is proposed to measure the spin torque exerted by the spin current by measuring the twisted angle of the director axis of a nematic liquid crystal.
description: 6 pages, 2 figures. v2: version appeared in PRL
$J/ψ$ suppression in Au+Au collisions at RHIC : colour screening scenario in the bag model at variable participant numbers
Creators: name: Mishra, M.
name: Singh, C. P.
name: Menon, V. J.
name: Dubey, Ritesh Kumar
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We have modified the colour screening theory of Chu and Matsui by properly incorporating bag model equation of state for quark gluon plasma (QGP). We have also chosen the pressure parametrization rather than parametrizing energy density in the transverse plane. We assume that the QGP dense medium is expanding in the longitudinal direction obeying Bjorken boost invariant scaling law. Sequential melting of $χ_c$, $ψ^{'}$ and $J/ψ$ is also considered in this scenario. We have applied above formulation to the recent PHENIX experimental data of $J/ψ$ suppression in Au + Au collisions at RHIC. We find that the model gives a good description of data at mid-rapidity in terms of survival probability versus number of participants without any necessity of implementing (3+1)-dimensional expansion of the deconfined medium.
description: 13 pages, 2 figures
Market insights for the multi-unit reinvented toilet in Bangladesh
Creators: name: Baldi, Marjorie
name: , Bill
Publisher: name: Gates Open Research
Year: 2021

description: This report focuses on understanding the barriers and enablers for scaling on-site sanitation in Bangladesh, with a focus on how the Multi-Unit Reinvented Toilet (MURT) could enter the market and aid in the government’s vision of scaling safely managed sanitation across the country. This report also lays out various actions for key stakeholders required in the near-, medium-, and long-term to open the market and scale OSS solutions, in particular, the MURT.
Toward Usable Security Administration
Creators: name: Beznosov, Konstantin
Publisher: name: Zenodo
Year: 2005
Subjects: usable security
security administration
administration

description: Administration of protection mechanisms for large networked information enterprises is challenging due to large numbers of application instances resources and users, complex and dynamic business processes, and high (and always growing) volume of change because of the first two (large scale and dynamics). Significant portion of the complexity and the cost of security administration are due to the ineffective human computer interaction (HCI) models and interfaces employed in security administration.  This talk introduces an upcoming project which goal is to develop better ways of representing cognitive models and find efficient HCI techniques to improve security administration for large-scale networked information enterprises.
A case of mistaken identity? GRB 060912A and the nature of the long -- short GRB divide
Creators: name: Levan, A. J.
name: Jakobsson, P.
name: Hurkett, C.
name: Tanvir, N. R.
name: Gorosabel, J.
name: Vreeswijk, P.
name: Rol, E.
name: Chapman, R.
name: Gehrels, N.
name: O'Brien, P. T.
name: Osborne, J. P.
name: Priddey, R. S.
name: Kouveliotou, C.
name: Starling, R.
name: Berk, D. Vanden
name: Wiersema, K.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We investigate the origin of the GRB 060912A, which has observational properties that make its classification as either a long or short burst ambiguous. Short duration GRBs (SGRBs) are thought to have typically lower energies than long duration bursts, can be found in galaxies with populations of all ages and are likely to originate from different progenitors to the long duration bursts. However, it has become clear that duration alone is insufficient to make a distinction between the two populations in many cases, leading to a desire to find additional discriminators of burst type. GRB 060912A had a duration of 6 s and occurred only ~10 arcsec from a bright, low redshift ($z=0.0936$) elliptical galaxy, suggesting that this may have been the host, which would favour it being a short-burst. However, our deep optical imaging and spectroscopy of the location of GRB 060912A using the VLT shows that GRB 060912A more likely originates in a distant star forming galaxy at z=0.937, and is most likely a long burst. This demonstrates the risk in identifying bright, nearby galaxies as the hosts of given GRBs without further supporting evidence. Further, it implies that, in the absence of secure identifications, "host" type, or more broadly discriminators which rely on galaxy redshifts, may not be good indicators of the true nature of any given GRB.
description: 9 pages, 5 figures, accepted for publication in MNRAS
Exploring Fine-grained Task Parallelism on Simultaneous Multithreading Cores
Creators: name: Los, Denis
name: Petushkov, Igor
Publisher: name: arXiv
Year: 2024
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: FOS: Computer and information sciences

description: Nowadays, latency-critical, high-performance applications are parallelized even on power-constrained client systems to improve performance. However, an important scenario of fine-grained tasking on simultaneous multithreading CPU cores in such systems has not been well researched in previous works. Hence, in this paper, we conduct performance analysis of state-of-the-art shared-memory parallel programming frameworks on simultaneous multithreading cores using real-world fine-grained application kernels. We introduce a specialized and simple software-only parallel programming framework called Relic to enable extremely fine-grained tasking on simultaneous multithreading cores. Using Relic framework, we increase performance speedups over serial implementations of benchmark kernels by 19.1% compared to LLVM OpenMP, by 31.0% compared to GNU OpenMP, by 20.2% compared to Intel OpenMP, by 33.2% compared to X-OpenMP, by 30.1% compared to oneTBB, by 23.0% compared to Taskflow, and by 21.4% compared to OpenCilk.
Nonperturbative screening of the Landau pole
Creators: name: Giacosa, Francesco
name: Hofmann, Ralf
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Based on the trace anomaly for the energy-momentum tensor, an effective theory for the thermodynamics of the deconfining phase, and by assuming the asymptotic behavior to be determined by one-loop perturbation theory we compute the nonperturbative beta function for the fundamental coupling $g$ in SU(2) and SU(3) Yang-Mills theory. With increasing temperature we observe a very rapid approach to the perturbative running. The Landau pole is nonperturbatively screened.
description: 11 pages, 3 figures
Novel QCD Phenomena
Creators: name: Brodsky, Stanley J.
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: I discuss a number of novel topics in QCD, including the use of the AdS/CFT correspondence between Anti-de Sitter space and conformal gauge theories to obtain an analytically tractable approximation to QCD in the regime where the QCD coupling is large and constant. In particular, there is an exact correspondence between the fifth-dimension coordinate z of AdS space and a specific impact variable zeta which measures the separation of the quark constituents within the hadron in ordinary space-time. This connection allows one to compute the analytic form of the frame-independent light-front wavefunctions of mesons and baryons, the fundamental entities which encode hadron properties and allow the computation of exclusive scattering amplitudes. I also discuss a number of novel phenomenological features of QCD. Initial- and final-state interactions from gluon-exchange, normally neglected in the parton model, have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam Tung relation in Drell-Yan reactions, and nuclear shadowing and non-universal antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss tests of hidden color in nuclear wavefunctions, the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency, and anomalous heavy quark effects. The presence of direct higher-twist processes where a proton is produced in the hard subprocess can explain the large proton-to-pion ratio seen in high-centrality heavy-ion collisions.
description: Invited talk presented at the Workshop on High PT Physics at the LHC (LHC07), Jyvaskyla, Finland, 23-27 March 2007; typos corrected; added reference;resolution of figures improved
Oscillation of spin polarization in a two-dimensional hole gas under a perpendicular magnetic field
Creators: name: Kleinert, P.
name: Bryksin, V. V.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Spin-charge coupling is studied for a strongly confined two-dimensional hole gas subject to a perpendicular magnetic field. The study is based on spin-charge coupled drift-diffusion equations derived from quantum-kinetic equations in an exact manner. The spin-orbit interaction induces an extra out-of-plane spin polarization. This contribution exhibits a persistent oscillatory pattern in the strong-coupling regime.
description: 11 pages and 1 figure
An experimental test of non-local realism
Creators: name: Groeblacher, Simon
name: Paterek, Tomasz
name: Kaltenbaek, Rainer
name: Brukner, Caslav
name: Zukowski, Marek
name: Aspelmeyer, Markus
name: Zeilinger, Anton
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Most working scientists hold fast to the concept of 'realism' - a viewpoint according to which an external reality exists independent of observation. But quantum physics has shattered some of our cornerstone beliefs. According to Bell's theorem, any theory that is based on the joint assumption of realism and locality (meaning that local events cannot be affected by actions in space-like separated regions) is at variance with certain quantum predictions. Experiments with entangled pairs of particles have amply confirmed these quantum predictions, thus rendering local realistic theories untenable. Maintaining realism as a fundamental concept would therefore necessitate the introduction of 'spooky' actions that defy locality. Here we show by both theory and experiment that a broad and rather reasonable class of such non-local realistic theories is incompatible with experimentally observable quantum correlations. In the experiment, we measure previously untested correlations between two entangled photons, and show that these correlations violate an inequality proposed by Leggett for non-local realistic theories. Our result suggests that giving up the concept of locality is not sufficient to be consistent with quantum experiments, unless certain intuitive features of realism are abandoned.
description: Minor corrections to the manuscript, the final inequality and all its conclusions do not change; description of corrections (Corrigendum) added as new Appendix III; Appendix II replaced by a shorter derivation
Modelization of flow electrification in a polymer melt
Creators: name: Flores, F.
name: Graebling, D.
name: Allal, A.
name: Guerret-Piécourt, C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: Flow electrification of polymer melts is an important side effect of polymer processing. The studies dealing with this phenomenon are seldom and most of the scientific work has been focused on flow electrification of aqueous and insulating Newtonian liquids. From that prior art it is well established that the flow electrification in Newtonian liquids is a consequence of the formation of an ionic double layer. Convection of this layer induces the electrification of the liquid at the outlet of the pipe. In those models, the key parameters governing the flow electrification are thus the intrinsic electrical properties of the polymer and the flow characteristics. In this work, we reconsider the assumptions made previously and we propose a new approach to modelise the flow electrification in the particular case of non-Newtonian polymer materials in laminar flow conditions. We establish that, a key parameter for the electrification quantification in the polymer melt is the shape of the velocity profile. Additionally, in some cases, we show that a slip velocity at the polymer/die wall interface must be considered to describe accurately the electrification. As a consequence, we deduce that the slip velocity at the interface can be calculated by measuring the electrification: this work gives an alternative manner to measure the slip velocity during polymer flow.
Electrical charging during the sharkskin instability of a metallocene melt
Creators: name: Tonon, S.
name: Lavernhe-Gerbier, A.
name: Flores, F.
name: Allal, A.
name: Guerret-Piécourt, C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Flow instabilities are widely studied because of their economical and theoretical interest, however few results have been published about the polymer electrification during the extrusion. Nevertheless the generation of the electrical charges is characteristic of the interaction between the polymer melt and the die walls. In our study, the capillary extrusion of a metallocene polyethylene (mPE) through a tungsten carbide die is characterized through accurate electrical measurements thanks a Faraday pail. No significant charges are observed since the extrudate surface remains smooth. However, as soon as the sharkskin distortion appears, measurable charges are collected (around 5 10-8 C/m2). Higher level of charges are measured during the spurt or the gross-melt fracture (g.m.f) defects. This work is focused on the electrical charging during the sharkskin instability. The variation of the electrical charges versus the apparent wall shear stress is investigated for different die geometries. This curve exhibits a linear increase, followed by a sudden growth just before the onset of the spurt instability. This abrupt charging corresponds also to the end of the sharkskin instability. It is also well-known that wall slip appears just at the same time, with smaller velocity values than during spurt flow. Our results indicate that electrification could be a signature of the wall slip. We show also that the electrification curves can be shifted according to the time-temperature superposition principle, leading to the conclusion that molecular features of the polymer are also involved in this process.
Spatiotemporal Crossover between Low- and High-Temperature Dynamical Regimes in the Quantum Heisenberg Magnet
Creators: name: Dupont, Maxime
name: Sherman, Nicholas E.
name: Moore, Joel E.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The stranglehold of low temperatures on fascinating quantum phenomena in one-dimensional quantum magnets has been challenged recently by the discovery of anomalous spin transport at high temperatures. Whereas both regimes have been investigated separately, no study has attempted to reconcile them. For instance, the paradigmatic quantum Heisenberg spin-$1/2$ chain falls at low temperature within the Tomonaga-Luttinger liquid framework, while its high-temperature dynamics is superdiffusive and relates to the Kardar-Parisi-Zhang universality class in $1+1$ dimensions. This Letter aims at reconciling the two regimes. Building on large-scale matrix product state simulations, we find that they are connected by a temperature-dependent spatiotemporal crossover. As the temperature $T$ is reduced, we show that the onset of superdiffusion takes place at longer length and timescales $\propto 1/T$. This prediction has direct consequences for experiments including nuclear magnetic resonance: it is consistent with earlier measurements on the nearly ideal Heisenberg $S=1/2$ chain compound Sr$_2$CuO$_3$, yet calls for new and dedicated experiments.
description: 7 pages (4 figures) + 8 pages (10 figures)
MANAGING SECURITY AND EFFICIENCY CHALLENGES IN NUCLEAR REACTORS FOR INTERPLANETARY TRAVEL
Creators: name: Brandl, Edenilson
Publisher: name: Zenodo
Year: 2023
Subjects: Interplanetary travel
Nuclear reactors
Security challenges
Efficiency
Pareto principle
Total Productive Maintenance (TPM)
Space-specific hazards
Fuel selection
Microscopic reactors
Quality control

description: Interplanetary travel powered by nuclear reactors holds great promise for humanity's exploration of the cosmos but presents significant security and efficiency challenges. This article delves into the critical issues surrounding nuclear reactors in the context of space travel, emphasizing the need to prioritize security measures based on the Pareto principle and employ Total Productive Maintenance (TPM) principles to enhance safety. Space-specific hazards, fuel selection, and reactor design are explored to address security concerns. Additionally, achieving efficiency in microscopic nuclear reactors for deep space missions is discussed, with a focus on quality control, advanced materials, and compact designs. The importance of instrumentation, prioritization techniques, and quality control in monitoring stress and vibration in nuclear reactor components is highlighted. Understanding the impact of protons on reactor materials in radiation-rich environments is also examined. Overall, this article underscores the multifaceted nature of managing security and efficiency challenges in nuclear reactors for interplanetary travel, providing insights into the complex but essential aspects of ensuring the success and safety of space missions.

 

Durch Kernreaktoren angetriebene interplanetare Reisen sind vielversprechend für die Erforschung des Kosmos durch die Menschheit, stellen jedoch erhebliche Sicherheits- und Effizienzherausforderungen dar. Dieser Artikel befasst sich mit den kritischen Problemen im Zusammenhang mit Kernreaktoren im Kontext der Raumfahrt und betont die Notwendigkeit, Sicherheitsmaßnahmen auf der Grundlage des Pareto-Prinzips zu priorisieren und die Prinzipien der Total Productive Maintenance (TPM) anzuwenden, um die Sicherheit zu erhöhen. Weltraumspezifische Gefahren, Brennstoffauswahl und Reaktordesign werden untersucht, um Sicherheitsbedenken auszuräumen. Darüber hinaus wird die Erzielung von Effizienz in mikroskopisch kleinen Kernreaktoren für Weltraummissionen diskutiert, wobei der Schwerpunkt auf Qualitätskontrolle, fortschrittlichen Materialien und kompakten Designs liegt. Die Bedeutung von Instrumenten, Priorisierungstechniken und Qualitätskontrolle bei der Überwachung von Spannungen und Vibrationen in Kernreaktorkomponenten wird hervorgehoben. Es wird auch untersucht, wie sich Protonen auf Reaktormaterialien in strahlungsreichen Umgebungen auswirken. Insgesamt unterstreicht dieser Artikel die Vielschichtigkeit der Bewältigung von Sicherheits- und Effizienzherausforderungen in Kernreaktoren für interplanetare Reisen und bietet Einblicke in die komplexen, aber wesentlichen Aspekte der Gewährleistung des Erfolgs und der Sicherheit von Weltraummissionen.
Solutions to the generalized Eshelby conjecture for anisotropic media: Proofs of the weak version and counter-examples to the high-order and the strong versions
Creators: name: Yuan, Tianyu
name: Huang, Kefu
name: Wang, Jianxiang
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The Eshelby formalism for an inclusion in a solid is of significant theoretical and practical implications in mechanics and other fields of heterogeneous media. Eshelby's finding that a uniform eigenstrain prescribed in a solitary ellipsoidal inclusion in an infinite isotropic medium results in a uniform elastic strain field in the inclusion leads to the conjecture that the ellipsoid is the only inclusion that possesses the so-called Eshelby uniformity property. Previously, only the weak version of the conjecture has been proved for the isotropic medium, whereas the general validity of the conjecture for anisotropic media in three dimensions is yet to be explored. In this work, firstly, we present proofs of the weak version of the generalized Eshelby conjecture for anisotropic media that possess cubic, transversely isotropic, orthotropic, and monoclinic symmetries. Secondly, we prove that in these anisotropic media, there exist non-ellipsoidal inclusions that can transform particular polynomial eigenstrains of even degrees into polynomial elastic strain fields of the same even degrees in them. These results constitute counter-examples, in the strong sense, to the generalized high-order Eshelby conjecture (inverse problem of Eshelby's polynomial conservation theorem) for polynomial eigenstrains in both anisotropic media and the isotropic medium (quadratic eigenstrain only). These findings reveal striking richness of the uniformity between the eigenstrains and the correspondingly induced elastic strains in inclusions in anisotropic media beyond the canonical ellipsoidal inclusions. Since the strain fields in embedded and inherently anisotropic quantum dot crystals are effective tuning knobs of the quality of the emitted photons by the quantum dots, the results may have implications in the technology of quantum information, in addition to in mechanics and materials science.
description: arXiv admin note: text overlap with arXiv:2105.08297
Dynamic condensation of water at crack tips in fused silica glass
Creators: name: Ciccotti, M.
name: George, M.
name: Ranieri, V.
name: Wondraczek, L.
name: Marliere, C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Water molecules play a fundamental role in the physics of slow crack propagation in glasses. It is commonly understood that, during stress-corrosion, water molecules that move in the crack cavity effectively reduce the bond strength at the strained crack tip and, thus, support crack propagation. Yet the details of the environmental condition at the crack tip in moist air are not well determined. In a previous work, we reported direct evidence of the presence of a 100 nm long liquid condensate at the crack tip in fused silica glass during very slow crack propagation (10^-9 to 10^-10 m/s). These observations are based on in-situ AFM phase imaging techniques applied on DCDC glass specimens in controlled atmosphere. Here, we discuss the physical origin of the AFM phase contrast between the liquid condensate and the glass surface in relation to tip-sample adhesion induced by capillary bridges. We then report new experimental data on the water condensation length increase with relative humidity in the atmosphere. The measured condensation lengths were much larger than what predicted using the Kelvin equation and expected geometry of the crack tip.
description: Accepted in JNCS. In press
A stringy perspective on the coincidence problem
Creators: name: Cunillera, Francesc
name: Padilla, Antonio
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We argue that, for generic string compactifications, dark energy is likely to signal the beginning of the end of our universe, perhaps even through decompactification, with possible implications for the cosmological coincidence problem. Thanks to the scarcity (absence?) of stable de Sitter vacua, dark energy in string theory is assumed to take the form of a quintessence field in slow roll. As it rolls, a tower of heavy states will generically descend, triggering an apocalyptic phase transition in the low energy cosmological dynamics after at most a few hundred Hubble times. As a result, dark energy domination cannot continue indefinitely and there is at least a percentage chance that we find ourselves in the first Hubble epoch. We use a toy model of quintessence coupled to a tower of heavy states to explicitly demonstrate the breakdown in the cosmological dynamics as the tower becomes light. This occurs through a large number of corresponding particles being produced after a certain time, overwhelming quintessence. We also discuss some implications for early universe inflation.
description: 7 pages, 1 figure, published version
A new instability for finite Prandtl number rotating convection with free-slip boundary conditions
Creators: name: Ponty, Yannick
name: Passot, Thierry
name: Sulem, Pierre-Louis
Publisher: name: arXiv
Year: 2007
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: Rolls in finite Prandtl number rotating convection with free-slip top and bottom boundary conditions are shown to be unstable with respect to small angle perturbations for any value of the rotation rate. This instability is driven by the horizontal mean flow whose estimation requires a special singular perturbation analysis.
Algebraic entropy for face-centered quad equations
Creators: name: Gubbiotti, Giorgio
name: Kels, Andrew P.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 37A35, 39A14

description: In this paper we define the algebraic entropy test for face-centered quad equations, which are equations defined on vertices of a quadrilateral plus an additional interior vertex. This notion of algebraic entropy is applied to a recently introduced class of these equations that satisfy a new form of multidimensional consistency called consistency-around-a-face-centered-cube (CAFCC), whereby the system of equations is consistent on a face-centered cubic unit cell. It is found that for certain arrangements of equations (or pairs of equations) in the square lattice, all known CAFCC equations pass the algebraic entropy test possessing either quadratic or linear growth.
description: 46 pages; 13 figures; 2 tables
3D Radiative Hydrodynamics for Disk Stability Simulations: A Proposed Testing Standard and New Results
Creators: name: Boley, Aaron C.
name: Durisen, Richard H.
name: Nordlund, Aake
name: Lord, Jesse
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Recent three-dimensional radiative hydrodynamics simulations of protoplanetary disks report disparate disk behaviors, and these differences involve the importance of convection to disk cooling, the dependence of disk cooling on metallicity, and the stability of disks against fragmentation and clump formation. To guarantee trustworthy results, a radiative physics algorithm must demonstrate the capability to handle both the high and low optical depth regimes. We develop a test suite that can be used to demonstrate an algorithm's ability to relax to known analytic flux and temperature distributions, to follow a contracting slab, and to inhibit or permit convection appropriately. We then show that the radiative algorithm employed by Mejiá (2004) and Boley et al. (2006) and the algorithm employed by Cai et al. (2006) and Cai et al. (2007, in prep.) pass these tests with reasonable accuracy. In addition, we discuss a new algorithm that couples flux-limited diffusion with vertical rays, we apply the test suite, and we discuss the results of evolving the Boley et al. (2006) disk with this new routine. Although the outcome is significantly different in detail with the new algorithm, we obtain the same qualitative answers. Our disk does not cool fast due to convection, and it is stable to fragmentation. We find an effective $α\approx 10^{-2}$. In addition, transport is dominated by low-order modes.
description: Submitted to ApJ
Theoretical description of the neutron beta decay in the standard model at the level of 10^{-5}
Creators: name: Ivanov, A. N.
name: Höllwieser, R.
name: Troitskaya, N. I.
name: Wellenzohn, M.
name: Berdnkov, Ya. A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: In the framework of the Standard Model (SM) a theoretical description of the neutron beta decay is given at the level of 10^{-5}. The neutron lifetime and correlation coefficients of the neutron beta decay for a polarized neutron, a polarized electron and an unpolarized proton are calculated at the account for i) the radiative corrections of order O(αE_e/m_N) ~ 10^{-5} to Sirlin's outer and inner radiative corrections of order O(α/π), ii) the corrections of order O(E^2_e/m^2_N) ~ 10^{-5}, caused by weak magnetism and proton recoil, and iii) Wilkinson's corrections of order 10^{-5} (Wilkinson, Nucl. Phys. A377, 474 (1982)). These corrections define the SM background of the theoretical description of the neutron beta decay at the level of 10^{-5}, which is required by experimental searches of interactions beyond the SM with experimental uncertainties of a few parts of 10^{-5}.
description: 35 pages, 1 figure, The manuscript is revised in accordance with the version accepted for publication in Physical Review D
Complete complementarity relations: Connections with EPR realism and decoherence and extension to mixed quantum states
Creators: name: Basso, Marcos L. W.
name: Maziero, Jonas
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Wave-particle duality is an essential character of quantum systems. In the last few years, much progress has being made towards formally quantifying these quantum features. The properties of the quantum density matrix were shown to lead to duality inequalities for single-quanton mixed states and to triality identities, also known as complete complementarity relations (CCRs), for two-quanton pure states. In this article, we establish connections between CCRs and EPR (ir)realism, as formalized by Bilobran and Angelo in [Europhys. Lett. 112, 40005 (2015)]. Besides, we show that, for tripartite pure states $|ψ_{ABE}\rangle$, CCRs can be applied to obtain the system-environment entanglement of formation, $E_{f}(ρ_{AE})$, through the local information of a system $A$ and its classical correlation with an auxiliary system $B$. Moreover, we discuss CCRs in the context of the emergence of the pointer basis in the decoherence process identified via the constancy of system-apparatus classical correlations. We also obtain CCRs for purified mixed bipartite quantum-classical states. In addition, we derive CCR for mixed-bipartite two-qudit quantum states and discuss its interpretations.
description: 6 pages. Accepted for publication in Europhysics Letters