cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Extended First-Principles Molecular Dynamics Method From Cold Materials to Hot Dense Plasmas
Creators: name: Zhang, Shen
name: Wang, Hongwei
name: Kang, Wei
name: Zhang, Ping
name: He, Xian-Tu
Publisher: name: arXiv
Year: 2016
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: An extended first-principles molecular dynamics (FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD method in the calculation of dense plasmas. The extended method treats the wave functions of high energy electrons as plane waves analytically, and thus expands the application of the FPMD method to the region of hot dense plasmas without suffering from the formidable computational costs. In addition, the extended method inherits the high accuracy of the Kohn-Sham scheme and keeps the information of elec- tronic structures. This gives an edge to the extended method in the calculation of the lowering of ionization potential, X-ray absorption/emission spectra, opacity, and high-Z dense plasmas, which are of particular interest to astrophysics, inertial confinement fusion engineering, and laboratory astrophysics.
Temperature dependence of the electrical resistivity and the anisotropic magnetoresistance (AMR) of electrodeposited Ni Co alloys
Creators: name: Tóth, B. G.
name: Péter, L.
name: Révész, Á.
name: Pádár, J.
name: Bakonyi, I.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The electrical resistivity and the anisotropic magnetoresistance (AMR) was investigated for Ni Co alloys at and below room temperature. The Ni Co alloy layers having a thickness of about 2 um were prepared by electrodeposition on Si wafers with evaporated Cr and Cu underlayers. The alloy composition was varied in the whole concentration range by varying the ratio of Ni sulfate and Co sulfate in the electrolyte. The Ni Co alloy deposits were investigated first in the as deposited state on the substrates and then, by mechanically stripping them from the substrates, as self supporting layers both without and after annealing. According to an X ray diffraction study, a strongly textured face centered cubic (fcc) structure was formed in the as deposited state with an average grain size of about 10 nm. Upon annealing, the crystal structure was retained whereas the grain size increased by a factor of 3 to 5, depending on alloy composition. The zero field resistivity decreased strongly by annealing due to the increased grain size. The annealing hardly changed the AMR below 50 at.% Co but strongly decreased it above this concentration. The composition dependence of the resistivity and the AMR of the annealed Ni Co alloy deposits was in good quantitative agreement with the available literature data both at 13 K and at room temperature. Both transport parameters were found to exhibit a pronounced maximum in the composition range between 20 and 30 at.% Co and the data of the Ni Co alloys fit well to the limiting values of the pure component metals (fcc Ni and fcc Co). The only theoretical calculation reported formerly on fcc Ni Co alloys yielded at T=0K a resistivity value smaller by a factor of 5 and an AMR value larger by a factor of about 2 than the corresponding low temperature experimental data, although the theoretical results properly reproduced the composition dependence of both quantities.
description: 27 pages, 10 figures
Photospheric and chromospheric magnetic activity of seismic solar analogs. Observational inputs on the solar/stellar connection from Kepler and Hermes
Creators: name: Salabert, D.
name: Garcia, R. A.
name: Beck, P. G.
name: Egeland, R.
name: Palle, P. L.
name: Mathur, S.
name: Metcalfe, T. S.
name: Nascimento, J. -D. do
name: Ceillier, T.
name: Andersen, M. F.
name: Hage, A. Trivino
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We identify a set of 18 solar analogs among the seismic sample of solar-like stars observed by the Kepler satellite rotating between 10 and 40 days. This set is constructed using the asteroseismic stellar properties derived using either the global oscillation properties or the individual acoustic frequencies. We measure the magnetic activity properties of these stars using observations collected by the photometric Kepler satellite and by the ground-based, high-resolution Hermes spectrograph mounted on the Mercator telescope. The photospheric (Sph) and chromospheric (S index) magnetic activity levels of these seismic solar analogs are estimated and compared in relation to the solar activity. We show that the activity of the Sun is comparable to the activity of the seismic solar analogs, within the maximum-to-minimum temporal variations of the 11-year solar activity cycle 23. In agreement with previous studies, the youngest stars and fastest rotators in our sample are actually the most active. The activity of stars older than the Sun seems to not evolve much with age. Furthermore, the comparison of the photospheric, Sph, with the well-established chromospheric, S index, indicates that the Sph index can be used to provide a suitable magnetic activity proxy which can be easily estimated for a large number of stars from space photometric observations.
description: Accepted for publication in A&A
Explainable Artificial Intelligence for Assault Sentence Prediction in New Zealand
Creators: name: Rodger, Harry
name: Lensen, Andrew
name: Betkier, Marcin
Publisher: name: Open Access Te Herenga Waka-Victoria University of Wellington
Year: 2022
Subjects: Uncategorized

description: The judiciary has historically been conservative in its use of Artificial Intelligence, but recent advances in machine learning have prompted scholars to reconsider such use in tasks like sentence prediction. This paper investigates by experimentation the potential use of explainable artificial intelligence for predicting imprisonment sentences in assault cases in New Zealand’s courts. We propose a proof-of-concept explainable model and verify in practice that it is fit for purpose, with predicted sentences accurate to within one year. We further analyse the model to understand the most influential phrases in sentence length prediction. We conclude the paper with an evaluative discussion of the future benefits and risks of different ways of using such an AI model in New Zealand’s courts.
Significantly improving stellar mass and radius estimates: A new reference function for the Δν scaling relation
Creators: name: Guggenberger, Elisabeth
name: Hekker, Saskia
name: Basu, Sarbani
name: Bellinger, Earl
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The scaling relations between global asteroseismic observables and stellar properties are widely used to estimate masses and radii of stars exhibiting solar-like oscillations. Since the mass and radius of the Sun are known independently, the Sun is commonly used as a reference to scale to. However, the validity of the scaling relations depends on the homology between the star under study and the reference star. Solar-like oscillators span a wide range of masses and metallicities, as well as evolutionary phases. Most of these stars are therefore not homologous to the Sun. This leads to errors of up to 10% (5%) in mass (radius) when using the asteroseismic scaling relations with the Sun as the reference. In this paper we derive a reference function to replace the solar-reference value used in the large-frequency-separation scaling relation. Our function is the first that depends on both effective temperature and metallicity, and is applicable from the end of the main sequence to just above the bump on the red giant branch. This reference function improves the estimates of masses and radii determined through scaling relations by a factor of 2, i.e. allows masses and radii to be recovered with an accuracy of 5% and 2%, respectively.
description: 6 pages, 4 figures, accepted for publication in MNRAS
Mass decomposition of SLACS lens galaxies in Weyl conformal gravity
Creators: name: Potapov, Alexander A.
name: Izmailov, Ramil N.
name: Nandi, Kamal K.
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study here, using the Mannheim-Kazanas solution of Weyl conformal theory, the mass decomposition in the representative subsample of $57$ early-type elliptical lens galaxies of the SLACS on board the HST. We begin by showing that the solution need not be an exclusive solution of conformal gravity but can also be viewed as a solution of a class of $f(R)$ gravity theories coupled to non-linear electrodynamics thereby rendering the ensuing results more universal. Since lensing involves light bending, we shall first show that the solution adds to Schwarzschild light bending caused by the luminous mass ($M_{\ast }$) a positive contribution $+γR$ contrary to the previous results in the literature, thereby resolving a long standing problem. The cause of the error is critically examined. Applying the expressions for light bending together with an input equating Einstein and Weyl angles, we develop a novel algorithm for separating the luminous component from the total lens mass (luminous+dark) within the Einstein radius. Our results indicate that the luminous mass estimates differ from the observed total lens masses by a linear proportionality factor. In quantitative detail, we observe that the ratios of luminous over total lens mass ($f^{\ast }$) within the Einstein radius of individual galaxies take on values near unity, many of which remarkably fall inside or just marginally outside the specified error bars obtained from a simulation based on the Bruzual-Charlot stellar population synthesis model together with the Salpeter IMF favored on the ground of metallicity [Grillo,2009]. We shall also calculate the average dark matter density of individual galaxies within their respective Einstein spheres. The present approach, being truly analytic, seems to be the first of its kind attempting to provide a new decomposition scheme distinct from the simulational ones.
description: 32 pages, 4 figures, 2 tables
Two NIRCam channels are Better than One: How JWST Can Do More Science with NIRCam's Short-Wavelength Dispersed Hartmann Sensor
Creators: name: Schlawin, Everett
name: Rieke, Marcia
name: Leisenring, Jarron
name: Greene, Tom
name: Walker, Lisa May
name: Fraine, Jonathan
name: Kelly, Doug
name: Misselt, Karl
name: Line, Michael
name: Stansberry, John
name: Lewis, Nikole
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The James Webb Space Telescope (JWST) offers unprecedented sensitivity, stability, and wavelength coverage for transiting exoplanet studies, opening up new avenues for measuring atmospheric abundances, structure, and temperature profiles. Taking full advantage of JWST spectroscopy of planets from 0.6um to 28um, however, will require many observations with a combination of the NIRISS, NIRCam, NIRSpec, and MIRI instruments. In this white paper, we discuss a new NIRCam mode (not yet approved or implemented) that can reduce the number of necessary observations to cover the 1.0um to 5.0um wavelength range. Even though NIRCam was designed primarily as an imager, it also includes several grisms for phasing and aligning JWST's 18 hexagonal mirror segments. NIRCam's long-wavelength channel includes grisms that cover 2.4um to 5.0um with a resolving power of R = 1200 - 1550 using two separate configurations. The long-wavelength grisms have already been approved for science operations, including wide field and single object (time series) slitless spectroscopy. We propose a new mode that will simultaneously measure spectra for science targets in the 1.0um to 2.0um range using NIRCam's short-wavelength channel. This mode, if approved, would take advantage of NIRCam's Dispersed Hartmann Sensor (DHS), which produces 10 spatially separated spectra per source at R ~ 300. We discuss the added benefit of the DHS in constraining abundances in exoplanet atmospheres as well as its ability to observe the brightest systems. The DHS essentially comes for free (at no time cost) with any NIRCam long-wavelength grism observation, but the detector integration parameters have to be selected to ensure that the long-wavelength grism observations do not saturate and that JWST data volume downlink constraints are not violated.
description: 10 pages, accepted to PASP
Rigorous Multiple-Precision Evaluation of D-Finite Functions in SageMath
Creators: name: Mezzarobba, Marc
Publisher: name: arXiv
Year: 2016
Subjects: subject: Symbolic Computation (cs.SC)
subject: FOS: Computer and information sciences

description: We present a new open source implementation in the SageMath computer algebra system of algorithms for the numerical solution of linear ODEs with polynomial coefficients. Our code supports regular singular connection problems and provides rigorous error bounds.
A single-mode external cavity diode laser using an intra-cavity atomic Faraday filter with short-term linewidth $<400$ kHz and long-term stability of $<1$ MHz
Creators: name: Keaveney, James
name: Hamlyn, William J
name: Adams, Charles S
name: Hughes, Ifan G
Publisher: name: arXiv
Year: 2016
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Instrumentation and Detectors (physics.ins-det)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We report on the development of a diode laser system - the `Faraday laser' - using an atomic Faraday filter as the frequency-selective element. In contrast to typical external-cavity diode laser systems which offer tunable output frequency but require additional control systems in order to achieve a stable output frequency, our system only lases at a single frequency, set by the peak transmission frequency of the internal atomic Farady filter. Our system has both short-term and long-term stability of less than 1~MHz, which is less than the natural linewidth of alkali-atomic D-lines, making similar systems suitable for use as a `turn-key' solution for laser cooling experiments.
Detection of a dearth of stars with zero angular momentum in the solar neighbourhood
Creators: name: Hunt, Jason A. S.
name: Bovy, Jo
name: Carlberg, Raymond G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We report on the detection in the combined $Gaia$-DR1/RAVE data of a lack of disk stars in the solar neighbourhood with velocities close to zero angular momentum. We propose that this may be caused by the scattering of stars with very low angular momentum onto chaotic, halo-type orbits when they pass through the Galactic nucleus. We model the effect in a Milky-Way like potential and fit the resulting model directly to the data, finding a likelihood ($\sim2.7σ$) of a dip in the distribution. Using this effect, we can make a dynamical measurement of the Solar rotation velocity around the Galactic center: $v_{\odot}=239\pm9$ km s$^{-1}$. Combined with the measured proper motion of Sgr A$^*$, this measurement gives a measurement of the distance to the Galactic centre: $R_0=7.9\pm0.3$ kpc.
description: 5 pages, 4 figures, submitted to ApJL
Giant photon gain in large-scale quantum dot circuit-QED systems
Creators: name: Agarwalla, Bijay Kumar
name: Kulkarni, Manas
name: Mukamel, Shaul
name: Segal, Dvira
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Motivated by recent experiments on the generation of coherent light in engineered hybrid quantum systems, we investigate gain in a microwave photonic cavity coupled to quantum dot structures, and develop concrete directions for achieving a giant amplification in photon transmission. We propose two architectures for scaling up the electronic gain medium: (i) $N$ double quantum dot systems (N-DQD), (ii) $M$ quantum dots arranged in series akin to a quantum cascade laser setup. In both setups, the fermionic reservoirs are voltage biased, and the quantum dots are coupled to a single-mode cavity. Optical amplification is explained based on a sum rule for the transmission function, and it is determined by an intricate competition between two different processes: charge density response in the gain medium, and cavity losses to input and output ports. The same design principle is also responsible for the corresponding giant amplification in other photonic observables, mean photon number and emission spectrum, thereby realizing a quantum device that behaves as a giant microwave amplifier.
description: 6 pages, 5 figures
Compression and phase diagram of lithium hydrides at elevated pressures and temperatures by first-principles calculations
Creators: name: Chen, Yang M.
name: Chen, Xiang R.
name: Wu, Qiang
name: Geng, Hua Y.
name: Yan, Xiao Z.
name: Wang, Yi X.
name: Wang, Zi W.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences
subject: 82D20

description: High pressure and high temperature properties of AB (A = $^6$Li, $^7$Li; B = H, D, T) are investigated with first-principles method comprehensively. It is found that the H$^{-}$ sublattice features in the low-pressure electronic structure near the Fermi level of LiH are shifted to that dominated by the Li$^{+}$ sublattice in compression. The lattice dynamics is studied in quasi-harmonic approximation, from which the phonon contribution to the free energy and the isotopic effects are accurately modelled with the aid of a parameterized double-Debye model. The obtained equation of state (EOS) matches perfectly with available static experimental data. The calculated principal Hugoniot is also in accordance with that derived from shock wave experiments. Using the calculated principal Hugoniot and the previous theoretical melting curve, we predict a shock melting point at 56 GPa and 1923 K. In order to establish the phase diagram for LiH, the phase boundaries between the B1 and B2 solid phases are explored. The B1-B2-liquid triple point is determined at about 241 GPa and 2413 K. The remarkable shift in the phase boundaries by isotopic effect and temperature reveal the significant role played by lattice vibrations. Furthermore, the Hugoniot of the static-dynamic coupling compression is assessed. Our EOS suggests that a precompression of the sample to 50 GPa will allow the shock Hugoniot passing through the triple point and entering the B2 solid phase. This transition leads to a discontinuity with 4.6% volume collapse, about four times greater than the same B1-B2 transition at zero temperature.
description: 25 pages, 9 figures
The Stellar Density Profile of the Distant Galactic Halo
Creators: name: Slater, Colin T.
name: Nidever, David L.
name: Munn, Jeffrey A.
name: Bell, Eric F.
name: Majewski, Steven R.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We use extensive gravity-sensitive DDO 51 photometry over 5100 square degrees, combined with SDSS broadband photometry, to select a catalog of $\sim 4,000$ giant stars covering a large fraction of the high Galactic latitude sky and reaching out to $\sim 80$ kpc in the Galactic halo. This sample of bright and unbiased tracers enables us to measure the radial profile and 3D structure of the stellar halo to large distance which had previously only been measured with sparse tracers or small samples. Using population synthesis models to reproduce the observed giant star luminosity function, we find that the halo maintains a $r^{-3.5}$ profile from $30$ to $80$ kpc with no signs of a truncation or sharp break over this range. The radial profile measurement is largely insensitive to individual halo substructure components, but we find that attempting to measure the shape of the halo is overwhelmed by the Sagittarius stream such that no ellipsoidal shape is a satisfactory description in this region. These measurements allow us to begin placing the Milky Way in context with the growing sample of external galaxies where similar halo profile measurements are available, with the goal of further linking the properties of stellar halos to the accretion histories that formed them.
description: Accepted to ApJ
Finite nilpotent groups coincide with their $2$-closures in all of their faithful permutation representations
Creators: name: Abdollahi, Alireza
name: Arezoomand, Majid
Publisher: name: arXiv
Year: 2016
Subjects: subject: Group Theory (math.GR)
subject: FOS: Mathematics

description: Here we show that a finite nilpotent group is 2-closed if and only if it is either cyclic or a direct product of a generalized quaternion group with a cyclic group of odd order.
Age velocity dispersion relations and heating histories in disc galaxies
Creators: name: Aumer, Michael
name: Binney, James
name: Schönrich, Ralph
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We analyse the heating of stellar discs by non axisymmetric structures and giant molecular clouds (GMCs) in N-body simulations of growing disc galaxies. The analysis resolves long-standing discrepancies between models and data by demonstrating the importance of distinguishing between measured age-velocity dispersion relations (AVRs) and the heating histories of the stars that make up the AVR. We fit both AVRs and heating histories with formulae proportional to t^beta and determine the exponents beta_R and beta_z derived from in-plane and vertical AVRs and ~beta_R and ~beta_z from heating histories. Values of beta_z are in almost all simulations larger than values of ~beta_z, whereas values of beta_R are similar to or mildly larger than values of ~beta_R. Moreover, values of beta_z (~beta_z) are generally larger than values of beta_R (~beta_R). The dominant cause of these relations is the decline over the life of the disc in importance of GMCs as heating agents relative to spiral structure and the bar. We examine how age errors and biases in solar neighbourhood surveys influence the measured AVR: they tend to decrease beta values by smearing out ages and thus measured dispersions. We compare AVRs and velocity ellipsoid shapes sigma_z/sigma_R from simulations to Solar neighbourhood data. We conclude that for the expected disc mass and dark halo structure, combined GMC and spiral/bar heating can explain the AVR of the Galactic thin disc. Strong departures of the disc mass or the dark halo structure from expectation spoil fits to the data.
description: Accepted for publication in MNRAS, 19 pages, 8 figures, 1 table
Proceedings of the 2013 European School of High-Energy Physics (ESHEP 2013), Paradfurdo, Hungary, 5-18 Jun 2013
Creators: name: Mulders, M.
name: Perez, G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The European School of High-Energy Physics is intended to give young physicists an introduction to the theoretical aspects of recent advances in elementary particle physics. These proceedings contain lecture notes on the Standard Model of electroweak interactions, quantum chromodynamics, Higgs physics, physics beyond the Standard Model, flavour physics, and practical statistics for particle physicists.
description: 6 lectures, 333 pages, published as CERN Yellow Report https://e-publishing.cern.ch/index.php/CYR/issue/view/3
Surpassing the shot-noise limit by homodyne-mediated feedback
Creators: name: Zhang, Guofeng
name: Zhu, Hanjie
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Entangled systems with large quantum Fisher information (QFI) can be used to outperform the standard quantum limit of the separable systems in quantum metrology. However, the interaction between the system and the environments inevitably leads to decoherence and decrease of the QFI, and it is not clear whether the entanglement systems can be better resource than separable systems in the realistic physical condition. In this work, we study the steady QFI of two driven and collectively damped qubits with homodyne-mediated feedback. We show that the steady QFI can be significantly enhanced both in the cases of symmetric feedback and nonsymmetric feedback, and the shot-noise limit of separable states can be surpassed in both cases. The QFI can even achieve the Heisenberg limit for appropriate feedback parameters and initial conditions in the case of symmetric feedback. We also show that an initial-condition-independent steady QFI can be obtained by using nonsymmetric feedback.
description: 5 pages, 3 figures
The SLUGGS Survey: stellar masses and effective radii of early-type galaxies from Spitzer Space Telescope 3.6$μ$m imaging
Creators: name: Forbes, Duncan A.
name: Sinpetru, Luciana
name: Savorgnan, Giulia
name: Romanowsky, Aaron J.
name: Usher, Christopher
name: Brodie, Jean
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Galaxy starlight at 3.6$μ$m is an excellent tracer of stellar mass. Here we use the latest 3.6$μ$m imaging from the Spitzer Space Telescope to measure the total stellar mass and effective radii in a homogeneous way for a sample of galaxies from the SLUGGS survey. These galaxies are representative of nearby early-type galaxies in the stellar mass range of 10 $
description: 15 pages, accepted for publication in MNRAS
Neutron monitors and muon detectors for solar modulation studies: 2. $ϕ$ time series
Creators: name: Ghelfi, A.
name: Maurin, D.
name: Cheminet, A.
name: Derome, L.
name: Hubert, G.
name: Melot, F.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The level of solar modulation at different times (related to the solar activity) is a central question of solar and galactic cosmic-ray physics. In the first paper of this series, we have established a correspondence between the uncertainties on ground-based detectors count rates and the parameter $ϕ$ (modulation level in the force-field approximation) reconstructed from these count rates. In this second paper, we detail a procedure to obtain a reference $ϕ$ time series from neutron monitor data. We show that we can have an unbiased and accurate $ϕ$ reconstruction ($Δϕ/ϕ\simeq 10\%$). We also discuss the potential of Bonner spheres spectrometers and muon detectors to provide $ϕ$ time series. Two by-products of this calculation are updated $ϕ$ values for the cosmic-ray database and a web interface to retrieve and plot $ϕ$ from the 50's to today (\url{http://lpsc.in2p3.fr/crdb}).
description: 15 pages, 5 figures, 2 tables. AdSR, in press. Web interface to get modulation parameter phi(t): new tab in http://lpsc.in2p3.fr/crdb
Toric Fano varieties associated to building sets
Creators: name: Suyama, Yusuke
Publisher: name: arXiv
Year: 2016
Subjects: subject: Algebraic Geometry (math.AG)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: Primary 14M25, Secondary 14J45, 05C20

description: We characterize building sets whose associated nonsingular projective toric varieties are Fano. Furthermore, we show that all such toric Fano varieties are obtained from smooth Fano polytopes associated to finite directed graphs.
description: 11 pages, 3 figures
UKIRT microlensing surveys as a pathfinder for $WFIRST$: The detection of five highly extinguished low-$|b|$ events
Creators: name: Shvartzvald, Y.
name: Bryden, G.
name: Gould, A.
name: Henderson, C. B.
name: Howell, S. B.
name: Beichman, C.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Optical microlensing surveys are restricted from detecting events near the Galactic plane and center, where the event rate is thought to be the highest, due to the high optical extinction of these fields. In the near-infrared (NIR), however, the lower extinction leads to a corresponding increase in event detections and is a primary driver for the wavelength coverage of the $WFIRST$ microlensing survey. During the 2015 and 2016 bulge observing seasons we conducted NIR microlensing surveys with UKIRT in conjunction with and in support of the $Spitzer$ and $Kepler$ microlensing campaigns. Here we report on five highly extinguished ($A_H=0.81-1.97$), low-Galactic latitude ($-0.98\le b\le -0.36$) microlensing events discovered from our 2016 survey. Four of them were monitored with an hourly cadence by optical surveys but were not reported as discoveries, likely due to the high extinction. Our UKIRT surveys and suggested future NIR surveys enable the first measurement of the microlensing event rate in the NIR. This wavelength regime overlaps with the bandpass of the filter in which the $WFIRST$ microlensing survey will conduct its highest-cadence observations, making this event rate derivation critically important for optimizing its yield.
description: 12 pages, 3 figures, 2 tables. ApJL submitted
Consistency and Trust in Peer Data Exchange Systems
Creators: name: Bertossi, Leopoldo
name: Bravo, Loreto
Publisher: name: arXiv
Year: 2016
Subjects: subject: Databases (cs.DB)
subject: Artificial Intelligence (cs.AI)
subject: Logic in Computer Science (cs.LO)
subject: FOS: Computer and information sciences

description: We propose and investigate a semantics for "peer data exchange systems" where different peers are related by data exchange constraints and trust relationships. These two elements plus the data at the peers' sites and their local integrity constraints are made compatible via a semantics that characterizes sets of "solution instances" for the peers. They are the intended -possibly virtual- instances for a peer that are obtained through a data repair semantics that we introduce and investigate. The semantically correct answers from a peer to a query, the so-called "peer consistent answers", are defined as those answers that are invariant under all its different solution instances. We show that solution instances can be specified as the models of logic programs with a stable model semantics. The repair semantics is based on null values as used in SQL databases, and is also of independent interest for repairs of single databases with respect to integrity constraints.
description: To appear in Theory and Practice of Logic Programming (TPLP). It includes appendix that will be published only in electronic format
Debonding model for nonlinear Fe-SMA strips bonded with nonlinear adhesives
Creators: name: Li, Lingzhen
name: Chatzi, Eleni
name: Ghafoori, Elyas
Publisher: name: Kidlington : Elsevier Science
Year: 2023
Subjects: subject: Bond capacity
subject: Bond–slip behavior
subject: Full-range behavior
subject: Interfacial fracture energy
subject: Iron-based shape memory alloys (Fe-SMAs)
subject: Memory steel
subject: Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik

description: The application of adhesively-bonded joints for strengthening of structures using iron-based shape memory alloys (Fe-SMAs) has recently emerged in construction. Fe-SMAs and the majority of structural adhesives exhibit a pronounced nonlinear material behavior, which may result in a favorable ductile failure mechanism. The development, however, of a mechanical model to predict the structural behavior of the joint is non-trivial due to the presence of nonlinearity in the adherent and adhesive. This study aims to propose a semi-analytical and semi-numerical model for describing the mechanical behavior of Fe-SMA-to-steel adhesively bonded joints. The developed model serves three main functions: (i) estimating the bond capacity for a given interfacial fracture energy, and vice versa; (ii) processing the bond–slip (t-s) behavior directly from the load–displacement (F-Δ) curve, and vice versa; and (iii) delivering a numerical method to simulate the full-range mechanical behavior of the bonded joints, namely the behavior at different loading stages. The model is validated using the experimental testing of 26 Fe-SMA-to-steel lap-shear joints, as well as 24 further bonded joints subject to shear with different adherents (e.g., stainless steel strips and Nickel–Titanium SMA wires) and base materials (e.g., concrete and composite polymer). An experimental data processing protocol, on the basis of the experimentally measured force–displacement (F-Δ) behavior and the distributed displacement along the bond line (s-x) via the Digital Image Correlation (DIC) technique, is further proposed to assess the full-range behavior of bonded joints.
Generating Quantum States through Spin Chain Dynamics
Creators: name: Kay, Alastair
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Spin chains can realise perfect quantum state transfer between the two ends via judicious choice of coupling strengths. In this paper, we study what other states can be created by engineering a spin chain. We conclude that, up to local phases, all single excitation quantum states with support on every site of the chain can be created. We pay particular attention to the generation of W-states that are superposed over every site of the chain.
description: 9 pages, 1 figure
Chemical analysis of a carbon-enhanced very metal-poor star: CD-27 14351
Creators: name: Karinkuzhi, Drisya
name: Goswami, Aruna
name: Masseron, Thomas
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present the first time abundance analysis of a very metal-poor carbon-enhanced star CD-27 14351 based on a high resolution (R ~ 48000) FEROS spectrum. Our abundance analysis performed using Local Thermodynamic Equilibrium (LTE) model atmospheres shows that the object is a cool star with stellar atmospheric parameters, effective temperature Teff = 4335 K, surface gravity log g = 0.5, microturbulence = 2.42 km/s, and, metallicity [Fe/H] = -2.6. The star exhibits high carbon and nitrogen abundances with [C/Fe] = 2.89 and [N/Fe] = 1.89. Overabundances of neutron-capture elements are evident in Ba, La, Ce, and Nd with estimated [X/Fe] > 1, the largest enhancement being seen in Ce with [Ce/Fe] = 2.63. While the first peak s-process elements Sr and Y are found to be enhanced with respect to Fe, ([Sr/Fe] = 1.73 and [Y/Fe] = 1.91) the third peak s-process element Pb could not be detected in our spectrum at the given resolution. Europium, primarily a r-process element also shows an enhancement with [Eu/Fe] = 1.65. With [Ba/Eu] = 0.12 the object CD-27 14351 satisfies the classification criterion for CEMP-r/s star. The elemental abundance distributions observed in this star is discussed in light of chemical abundances observed in other CEMP stars from literature.
description: 23 pages, 10 figures, Accepted for publication in ApJ
The Linear Instability of Dilute Ultrarelativistic $e^{\pm}$ Pair Beams
Creators: name: Chang, Philip
name: Broderick, Avery E.
name: Pfrommer, Christoph
name: Puchwein, Ewald
name: Lamberts, Astrid
name: Shalaby, Mohamad
name: Vasil, Geoffrey
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The annihilation of TeV photons from extragalactic TeV sources and the extragalactic background light produces ultrarelativistic $e^{\pm}$ beams, which are subject to powerful plasma instabilities that sap their kinetic energy. Here we study the linear phase of the plasma instabilities that these pair beams drive. To this end, we calculate the linear growth rate of the beam plasma and oblique instability in the electrostatic approximation in both the reactive and kinetic regimes, assuming a Maxwell-J{ü}ttner distribution for the pair beam. We reproduce the well-known reactive and kinetic growth rates for both the beam plasma and oblique mode. We demonstrate for the oblique instability that there is a broad spectrum of unstable modes that grow at the maximum rate for a wide range of beam temperatures and wave vector orientations relative to the beam. We also delineate the conditions for applicability for the reactive and kinetic regimes and find that the beam plasma mode transitions to the reactive regime at a lower Lorentz factor than the oblique mode due to a combination of their different scalings and the anisotropy of the velocity dispersions. Applying these results to the ultrarelativistic $e^{\pm}$ beams from TeV blazars, we confirm that these beams are unstable to both, the kinetic oblique mode and the reactive beam-plasma mode. These results are important in understanding how powerful plasma instabilities may sap the energy of the ultrarelativistic $e^{\pm}$ beams as they propagate through intergalactic space.
description: 13 pages, 4 figure, accepted to ApJ
Mechanisms underlying the abnormal respiratory-sympathetic phenotype of the Spontaneously Hypertensive Rat
Creators: name: Newbold, Tonique
Publisher: name: Macquarie University
Year: 2022
Subjects: Other education not elsewhere classified

description: There is an established link between sympathetic dysregulation and hypertension, with animal models showing a temporal phase shift in peak sympathetic activity from the postinspiratory (post-I) period to late inspiration. The mechanism driving altered respiratorysympathetic coupling in spontaneously hypertensive rats (SHR) is still unknown. It has been suggested that pathways driving post-I activity are overactive in SHRs, resulting in premature sympathetic activation. Alternatively, it has been suggested that abnormal excitatory connections between inspiratory neurons in PreBötC and the RVLM cause an increase in sympathetic activity during inspiration. This project used electrophysiological nerve recordings to compare vagal and sympathetic nerve activity between SHR and WKY rats. Additionally, larynx muscle movement was recorded using videography to directly measure post-I laryngeal adduction. It was expected that peak vagus activity would also be phase-shifted in SHRs, but results show similar timing of laryngeal adduction and vagal post-I activity in both strains, despite peak sympathetic activity occurring earlier in SHRs. It was also found that WKYs have a temporal phase shift in vagal post-I activity during hypoxemia, while SHRs showed no change. Hypoxemia delays sympathetic activity in SHRs, while the effect in WKYs is variable and shows no consistent pattern. These findings indicate thar sympathetic and vagal post-I activity are separate mechanisms that can be altered independently in response to homeostatic challenge. As vagal post-I activity is not phase shifted in SHRs, this supports the hypothesis that their altered respiratory-sympathetic coupling is due to a mechanism acting on the sympathetic nervous system directly, not one affecting post-I activity in general.
Decrypting the programming of β-methylation in virginiamycin M biosynthesis
Creators: name: Collin, Sabrina
name: Cox, Russell J.
name: Paris, Cédric
name: Jacob, Christophe
name: Chagot, Benjamin
name: Weissman, Kira J.
name: Gruez, Arnaud
Publisher: name: [London] : Nature Publishing Group UK
Year: 2023
Subjects: subject: Dewey Decimal Classification::500 | Naturwissenschaften

description: During biosynthesis by multi-modular trans-AT polyketide synthases, polyketide structural space can be expanded by conversion of initially-formed electrophilic ß-ketones into ß-alkyl groups. These multi-step transformations are catalysed by 3-hydroxy-3-methylgluratryl synthase cassettes of enzymes. While mechanistic aspects of these reactions have been delineated, little information is available concerning how the cassettes select the specific polyketide intermediate(s) to target. Here we use integrative structural biology to identify the basis for substrate choice in module 5 of the virginiamycin M trans-AT polyketide synthase. Additionally, we show in vitro that module 7, at minimum, is a potential additional site for ß-methylation. Indeed, analysis by HPLC-MS coupled with isotopic labelling and pathway inactivation identifies a metabolite bearing a second ß-methyl at the expected position. Collectively, our results demonstrate that several control mechanisms acting in concert underpin ß-branching programming. Furthermore, variations in this control – whether natural or by design – open up avenues for diversifying polyketide structures towards high-value derivatives.
Elevated Temperature Mechanical Characteristics and Fracture Behavior of a Novel Beta Titanium Alloy
Creators: name: Sajadifar, Seyed Vahid
name: Maier, Hans Jürgen
name: Niendorf, Thomas
name: Yapici, Guney Guven
Publisher: name: Basel : MDPI
Year: 2023
Subjects: subject: beta titanium
subject: dynamic precipitation
subject: dynamic recovery
subject: elevated temperature
subject: forming
subject: fracture morphology
subject: mechanical behavior
subject: Ti-5V-5Mo-5Cr-4Al alloy
subject: Dewey Decimal Classification::500 | Naturwissenschaften::540 | Chemie

description: In the present work, the elevated-temperature deformation characteristics and microstructural evolution of a Ti-5V-5Mo-5Cr-4Al alloy in solution-treatment conditions were studied under a tensile load at temperatures in the range of 25 to 550 °C and strain rates between 0.001 and 0.1 s-1. The results obtained indicated that, essentially, dynamic recovery (DRV) was the dominant softening mechanism in the case of the regimes considered. An analysis based on transmission electron microscopy (TEM) and the assessment of the mechanical behavior of the solution-heat-treated Ti-5V-5Mo-5Cr-4Al alloy revealed that dynamic precipitation (DPN) only took place at a strain rate of 0.001 s-1 and at temperatures of 450 °C and 500 °C. Void coalescence occurred upon an increase in the deformation temperature and a decrease in the strain rate due to a higher rate of diffusion and the provision of sufficient time for growth, respectively. The results obtained in the present study pave the way for the robust processing of this novel ß titanium alloy. Depending on the deformation parameters, the deformation characteristics can be governed by either DRV (at moderate temperatures) or DPN (at moderate temperatures and at low rates of deformation).
ON THE INFLUENCE OF DOSTOYEVSKI IN UNAMUNO´S WORK
Creators: name: Serrano, Jorge
Publisher: name: Zenodo
Year: 2023
Subjects: ideological coincidences, literary works, perception, human being, existence.

description: The objective of the document is to describe the ideological coincidences between Fyodor M Dostoyevski and Miguel de Unamuno as reflected in their novels, essays and personal documents. Likewise, through the bibliographical review, it aims to expose the relevant ideas of the Russian writer, and how similar to them can be found in the literary work of the Basque thinker. It is concluded that both writers expressed their perception of the human being and his existence in a literary way, although using each one a different form of exposition.
High harmonic interferometry of the Lorentz force in strong mid-infrared laser fields
Creators: name: Pisanty, Emilio
name: Hickstein, Daniel D.
name: Galloway, Benjamin R.
name: Durfee, Charles G.
name: Kapteyn, Henry C.
name: Murnane, Margaret M.
name: Ivanov, Misha
Publisher: name: arXiv
Year: 2016
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: The interaction of intense mid-infrared laser fields with atoms and molecules leads to a range of new opportunities, from the production of bright, coherent radiation in the soft x-ray range to imaging molecular structures and dynamics with attosecond temporal and sub-angstrom spatial resolution. However, all these effects, which rely on laser-driven recollision of an electron removed by the strong laser field and the parent ion, suffer from the rapidly increasing role of the magnetic field component of the driving pulse: the associated Lorentz force pushes the electrons off course in their excursion and suppresses all recollision-based processes, including high harmonic generation, elastic and inelastic scattering. Here we show how the use of two non-collinear beams with opposite circular polarizations produces a forwards ellipticity which can be used to monitor, control, and cancel the effect of the Lorentz force. This arrangement can thus be used to re-enable recollision-based phenomena in regimes beyond the long-wavelength breakdown of the dipole approximation, and it can be used to observe this breakdown in high-harmonic generation using currently-available light sources.
Fuentes de información y búsqueda bibliográfica
Creators: name: Heras-Robles, Inmaculada
Publisher: name: Zenodo
Year: 2022
Subjects: fuentes de información, búsqueda bibliográfica

description: Presentación del modulo fuentes de información y búsqueda bibliográfica dentro del curso Iniciación a los trabajo científicos en el ámbito de la acción social
Kelvin-Helmholtz instability in solar chromospheric jets: theory and observation
Creators: name: Kuridze, D.
name: Zaqarashvili, T. V.
name: Henriques, V.
name: Mathioudakis, M.
name: Keenan, F. P.
name: Hanslmeier, A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Using data obtained by the high resolution CRisp Imaging SpectroPolarimeter instrument on the Swedish 1-m Solar Telescope, we investigate the dynamics and stability of quiet-Sun chromospheric jets observed at disk center. Small-scale features, such as Rapid Redshifted and Blueshifted Excursions, appearing as high speed jets in the wings of the H$α$ line, are characterized by short lifetimes and rapid fading without any descending behavior. To study the theoretical aspects of their stability without considering their formation mechanism, we model chromospheric jets as twisted magnetic flux tubes moving along their axis, and use the ideal linear incompressible magnetohydrodynamic approximation to derive the governing dispersion equation. Analytical solutions of the dispersion equation indicate that this type of jet is unstable to Kelvin-Helmholtz instability (KHI), with a very short (few seconds) instability growth time at high upflow speeds. The generated vortices and unresolved turbulent flows associated with the KHI could be observed as broadening of chromospheric spectral lines. Analysis of the H$α$ line profiles shows that the detected structures have enhanced line widths with respect to the background. We also investigate the stability of a larger scale H$α$ jet that was ejected along the line-of-sight. Vortex-like features, rapidly developing around the jet's boundary, are considered as evidence of the KHI. The analysis of the energy equation in the partially ionized plasma shows that the ion-neutral collisions may lead to the fast heating of the KH vortices over timescales comparable to the lifetime of chromospheric jets.
description: 10 pages, 8 figures, accepted in ApJ