cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A kinematic study of central compact objects and their host supernova remnants
Creators: name: Mayer, Martin G. F.
name: Becker, Werner
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Context. Central compact objects (CCOs) are a peculiar class of neutron stars, primarily encountered close to the center of young supernova remnants (SNRs) and characterized by thermal X-ray emission. Aims. Our goal is to perform a systematic study of the proper motion of all known CCOs with appropriate data available. In addition, we aim to measure the expansion of three SNRs within our sample to obtain a direct handle on their kinematics and age. Methods. We analyze multiple archival Chandra data sets, consisting of HRC and ACIS observations separated by temporal baselines between 8 and 15 years. In order to correct for systematic astrometric uncertainties, we establish a reference frame using X-ray detected sources in Gaia DR2, to provide accurate proper motion estimates for our target CCOs. Complementarily, we use our coaligned data sets to trace the expansion of three SNRs by directly measuring the spatial offset of various filaments and ejecta clumps between different epochs. Results. In total, we present new proper motion measurements for six CCOs, among which we do not find any indication of a hypervelocity object. We tentatively identify direct signatures of expansion for the SNRs G15.9+0.2 and Kes 79, at estimated significance of $2.5σ$ and $2σ$, respectively. Moreover, we confirm recent results by Borkowski et al., measuring the rapid expansion of G350.1$-$0.3 at almost $6000\,{\rm km\,s^{-1}}$, which places its maximal age at $600-700$ years. The observed expansion, combined with the rather small proper motion of its CCO, implies the need for a very inhomogeneous circumstellar medium to explain the highly asymmetric appearance of the SNR. Finally, for the SNR RX J1713.7$-$3946, we combine previously published expansion measurements with our measurement of the CCO's proper motion to obtain a constraining upper limit of $1700$ years on the system's age.
description: 22+8 pages, 16+3 figures. Accepted for publication in Astronomy & Astrophysics
Gluon momentum fraction of the nucleon from lattice QCD
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: hep-lat
hep-ex
hep-ph
hep-th
nucl-th

description: © 2017 American Physical Society. We perform a direct calculation of the gluon momentum fraction of the nucleon, taking into account the mixing with the corresponding quark contribution. We use maximally twisted mass fermion ensembles with Nf=2+1+1 flavors at a pion mass of about 370 MeV and a lattice spacing of a≈0.082 fm and with Nf=2 flavors at the physical pion mass and a lattice spacing of a≈0.093 fm. We employ stout smearing to obtain a statistically significant result for the bare matrix elements. In addition, we perform a lattice perturbative calculation including two levels of stout smearing to carry out the mixing and the renormalization of the quark and gluon operators. We find, after conversion to the MS- scheme at a scale of 2 GeV xgR=0.284(27)(17)(24) for pion mass of about 370 MeV and xgR=0.267(22)(19)(24) for the physical pion mass. In the reported numbers, the first parenthesis indicates statistical uncertainties. The numbers in the second and third parentheses correspond to systematic uncertainties due to excited states contamination and renormalization, respectively.
Towards highly accurate calculations of parity violation in chiral molecules: relativistic coupled-cluster theory including QED-effects
Creators: name: Sunaga, Ayaki
name: Saue, Trond
Publisher: name: arXiv
Year: 2021
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Parity-violating energies $E_{PV}$ of the $H_2X_2$ X = O, S, Se, Te, Po) molecules are reported, calculated as analytical expectation values at the relativistic coupled-cluster singles-and-doubles (CCSD) level using property-optimized basis sets. Radiative corrections to the $E_{PV}$ was investigated using effective QED-potentials and found to reach a maximal value of 2.38% for $H_2Po_2$ . However, this result depends on the choice of effective self-energy potential and may indicate limitations to their domain of validity.
description: 15 pages
Real-Time Observation of Phonon-Mediated σ-π Interband Scattering in MgB2
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: cond-mat.supr-con

description: © 2017 American Physical Society. In systems having an anisotropic electronic structure, such as the layered materials graphite, graphene, and cuprates, impulsive light excitation can coherently stimulate specific bosonic modes, with exotic consequences for the emergent electronic properties. Here we show that the population of E2g phonons in the multiband superconductor MgB2 can be selectively enhanced by femtosecond laser pulses, leading to a transient control of the number of carriers in the σ-electronic subsystem. The nonequilibrium evolution of the material optical constants is followed in the spectral region sensitive to both the a- and c-axis plasma frequencies and modeled theoretically, revealing the details of the σ-π interband scattering mechanism in MgB2.
Torsional nodeless vibrations of quaking neutron star restored by combined forces of shear elastic and magnetic field stresses
Creators: name: Bastrukov, S. I.
name: Chen, G. -T.
name: Chang, H. -K.
name: Molodtsova, I. V.
name: Podgainy, D. V.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Within the framework of Newtonian magneto-solid-mechanics, relying on equations appropriate for a perfectly conducting elastic continuous medium threaded by a uniform magnetic field, the asteroseismic model of a neutron star undergoing axisymmetric global torsional nodeless vibrations under the combined action of Hooke's elastic and Lorentz magnetic forces is considered with emphasis on a toroidal Alfvén mode of differentially rotational vibrations about the dipole magnetic moment axis of the star. The obtained spectral equation for frequency is applied to $\ell$-pole identification of quasi-periodic oscillations (QPOs) of X-ray flux during the giant flares of SGR 1806-20 and SGR 1900+14. Our calculations suggest that detected QPOs can be consistently interpreted, within the framework of this model, as produced by global torsional nodeless vibrations of quaking magnetar if they are considered to be restored by the joint action of bulk forces of shear elastic and magnetic field stresses.
description: 18 pages, 5 figures; accepted in ApJ
Active Learning of Abstract Plan Feasibility
Creators: name: Noseworthy, Michael
name: Moses, Caris
name: Brand, Isaiah
name: Castro, Sebastian
name: Kaelbling, Leslie
name: Lozano-Pérez, Tomás
name: Roy, Nicholas
Publisher: name: arXiv
Year: 2021
Subjects: subject: Robotics (cs.RO)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Long horizon sequential manipulation tasks are effectively addressed hierarchically: at a high level of abstraction the planner searches over abstract action sequences, and when a plan is found, lower level motion plans are generated. Such a strategy hinges on the ability to reliably predict that a feasible low level plan will be found which satisfies the abstract plan. However, computing Abstract Plan Feasibility (APF) is difficult because the outcome of a plan depends on real-world phenomena that are difficult to model, such as noise in estimation and execution. In this work, we present an active learning approach to efficiently acquire an APF predictor through task-independent, curious exploration on a robot. The robot identifies plans whose outcomes would be informative about APF, executes those plans, and learns from their successes or failures. Critically, we leverage an infeasible subsequence property to prune candidate plans in the active learning strategy, allowing our system to learn from less data. We evaluate our strategy in simulation and on a real Franka Emika Panda robot with integrated perception, experimentation, planning, and execution. In a stacking domain where objects have non-uniform mass distributions, we show that our system permits real robot learning of an APF model in four hundred self-supervised interactions, and that our learned model can be used effectively in multiple downstream tasks.
description: To appear in Robotics: Science and Systems 2021
Toward broadband mechanical spectroscopy
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: cond-mat.soft

description: © 2017, National Academy of Sciences. All rights reserved. Diverse material classes exhibit qualitatively similar behavior when made viscous upon cooling toward the glass transition, suggesting a common theoretical basis. We used seven different measurement methods to determine the mechanical relaxation kinetics of a prototype molecular glass former over a temporal range of 13 decades and over a temperature range spanning liquid to glassy states. The data conform to time–temperature superposition for the main (alpha) process and to a scaling relation of schematic mode-coupling theory. The broadband mechanical measurements demonstrated have fundamental and practical applications in polymer science, geophysics, multifunctional materials, and other areas.
CLINICAL-DENTAL CHANGES IN THE ORAL CAVITY AFTER REMOVABLE DENTAL PROSTHESES.
Creators: name: Tuxtaeva, Maxsuda
Publisher: name: Zenodo
Year: 2025

description: Patients with partial or complete loss of teeth and chronic diseases of the oral mucosa often come to orthopedic dentists. The complexity of the rehabilitation of patients with partial or complete loss of teeth (adentia) is one of the pressing problems of orthopedic dentistry. One of a number of objective and subjective reasons for this is the muyan complexity of patients ' restorative orthopedic treatment.
Electronic origin of the spin-phonon coupling effect in transition-metal perovskites
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: cond-mat.mtrl-sci

description: © 2017 American Physical Society. By applying the Wannier-based extended Kugel-Khomskii model, we carry out first-principles calculations and electronic structure analysis to understand the spin-phonon coupling effect in transition-metal perovskites. We demonstrate the successful application of our approach to SrMnO3 and BiFeO3. We show that both the electron orbitals under crystal-field splitting and the electronic configuration should be taken into account in order to understand the large variances of spin-phonon coupling effects among various phonon modes as well as in different materials.
Photon beam asymmetry Σ for η and η′ photoproduction from the proton
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: Meson photoproduction
Eta photoproduction
Eta-prime photoproduction
Polarization observable
Photon beam asymmetry

description: © 2017 The Authors Measurements of the linearly-polarized photon beam asymmetry Σ for photoproduction from the proton of η and η′ mesons are reported. A linearly-polarized tagged photon beam produced by coherent bremsstrahlung was incident on a cryogenic hydrogen target within the CEBAF Large Acceptance Spectrometer. Results are presented for the γp→ηp reaction for incident photon energies from 1.070 to 1.876 GeV, and from 1.516 to 1.836 GeV for the γp→η′p reaction. For γp→ηp, the data reported here considerably extend the range of measurements to higher energies, and are consistent with the few previously published measurements for this observable near threshold. For γp→η′p, the results obtained are consistent with the few previously published measurements for this observable near threshold, but also greatly expand the incident photon energy coverage for that reaction. Initial analysis of the data reported here with the Bonn–Gatchina model strengthens the evidence for four nucleon resonances – the N(1895)1/2−, N(1900)3/2+, N(2100)1/2+ and N(2120)3/2− resonances – which presently lack the “four-star” status in the current Particle Data Group compilation, providing examples of how these new measurements help refine models of the photoproduction process.
RR Lyrae Stars In Stellar Streams with Gaia: The Escapers
Creators: name: Abbas, Mohamad
name: Grebel, Eva K.
name: Simunovic, Mirko
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We attempt to identify RR Lyrae (RRL) stars in stellar streams that might have escaped from seven globular clusters (GCs) based on proper motions, distances, color-magnitude diagrams, and other properties extracted from the Gaia Early Data Release 3 (EDR3) database. Specifically, we cross-match two large RRL stars catalogs (from Gaia DR2 and Catalina Sky Survey) with each other and with the EDR3 database and we end up with a sample of ~ 150,000 unique RRL stars. We calculate distances to RRL stars using the (M_G-[Fe/H]) and (M_V-[Fe/H]) absolute magnitude-metallicity relations and adopt [Fe/H] values for the GCs from different spectroscopic studies. We also constrain our search in areas where stellar streams associated with GCs were previously suggested or identified in other studies. We identify 24 RRL stars that might have escaped from the following seven GCs: Palomar 13 (Pal 13), NGC 6341 (M92), NGC 5904 (M5), NGC 5466, NGC 1261, NGC 288, and NGC 1851. We list our findings in Table 2.
description: Accepted for publication in ApJ, 14 pages, 6 figures, 1 table
A cosmic abundance standard: chemical homogeneity of the solar neighbourhood and the ISM dust-phase composition
Creators: name: Przybilla, Norbert
name: Nieva, Maria-Fernanda
name: Butler, Keith
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: A representative sample of unevolved early B-type stars in nearby OB associations and the field is analysed to unprecedented precision using NLTE techniques. The resulting chemical composition is found to be more metal-rich and much more homogeneous than indicated by previous work. A rms scatter of ~10% in abundances is found for the six stars (and confirmed by six evolved stars), the same as reported for ISM gas-phase abundances. A cosmic abundance standard for the present-day solar neighbourhood is proposed, implying mass fractions for hydrogen, helium and metals of X=0.715, Y=0.271 and Z=0.014. Good agreement with solar photospheric abundances as reported from recent 3D radiative-hydrodynamical simulations of the solar atmosphere is obtained. As a first application we use the cosmic abundance standard as a proxy for the determination of the local ISM dust-phase composition, putting tight observational constraints on dust models.
description: 4 pages, 2 figures. Accepted for publication in ApJ Letters
title: Frontmatter, Table of Contents, Preface, Conference Organization
Creators: name: Bezem, Marc
Publisher: name: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Year: 2011
Subjects: subject: Frontmatter
subject: Table of Contents
subject: Preface
subject: Conference Organization

description: Frontmatter, Table of Contents, Preface, Conference Organization
description: LIPIcs, Vol. 12, Computer Science Logic (CSL'11) - 25th International Workshop/20th Annual Conference of the EACSL, pages i-xix
Accretion onto Seed Black Holes in the First Galaxies
Creators: name: Milosavljevic, Milos
name: Bromm, Volker
name: Couch, Sean M.
name: Oh, S. Peng
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The validity of the hypothesis that the massive black holes in high redshift quasars grew from stellar-sized "seeds" is contingent on a seed's ability to double its mass every few ten million years. This requires that the seed accrete at approximately the Eddington-limited rate. In the specific case of radiatively efficient quasiradial accretion in a metal-poor protogalactic medium, for which the Bondi accretion rate is often prescribed in cosmological simulations of massive black hole formation, we examine the effects of the radiation emitted near the black hole's event horizon on the structure of the surrounding gas flow. We find that the radiation pressure from photoionization significantly reduces the steady-state accretion rate and renders the quasiradial accretion flow unsteady and inefficient. The time-averaged accretion rates are a small fraction of the Eddington-limited accretion rate for Thomson scattering. The pressure of Ly-alpha photons trapped near the HII region surrounding the black hole may further attenuate the inflow. These results suggest that an alternative to quasiradial, radiatively efficient Bondi-like accretion should be sought to explain the rapid growth of quasar-progenitor seed black holes.
description: replaced with significantly revised and expanded version; 14 pages, 2 figures
REACTION OF THE SEAMEN'S ORGANISM TO THE SIMULATION OF PROFESSIONAL ACTIVITY
Creators: name: Anastasiia, Novikova
Publisher: name: figshare
Year: 2021
Subjects: subject: 90399 Biomedical Engineering not elsewhere classified
subject: FOS: Medical engineering

description: The analyze of the factors that are influencing on the performance of the navigator professional activity is carried out. It is noted that the professional activity of the navigator is due to his personal qualities, which are formed both by personal physiological condition and the influence of external factors. Stressful situations are characterized by one common feature - the emergence of a person's acute internal conflict between the requirements of work and its capabilities. The analysis of the factors that are influencing to the navigator at navigation is carried out. It is noted that the importance of a positive or negative response to stressful situations depends on how the body builds its cognitive, emotional and behavioral coping strategies. Many regulatory systems take part in the body's stress response - the central nervous system, the autonomic nervous system and the system of neuro-endocrine regulation. Neurobiochemical changes are observed in human’ structures of the brain, which interfere with the work of the frontal cortex and the performance of its cognitive function. Cognitive stress can be interpreted as an integral link between physiological and psychosocial stress, on the one hand, and psychological stress, on the other. Assessment of the psychophysiological status of navigators was performed using a computerized software package of the Kherson Marine Training Center "Marin Pro Service". Conducted an examination to determine fatigue. The reaction of the cardiovascular system, sweating and morphology in response to work on the simulator were determined. The indicator of stress level is determined. The results show that the young body has more adaptive reserves to emotional stress.At the same time, professional training requires the navigator to be less prone to stress, which is adjusted by training on simulators in modeling an extreme situation.
Energy dependence of J/ψ production in Au + Au collisions at sNN=39,62.4 and 200GeV
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: hep-ex
nucl-ex

description: © 2017 The Author The inclusive J/ψ transverse momentum spectra and nuclear modification factors are reported at mid-rapidity (|y|<1.0) in Au + Au collisions at sNN = 39, 62.4 and 200 GeV taken by the STAR experiment. A suppression of J/ψ production, with respect to the production in p+p scaled by the number of binary nucleon–nucleon collisions, is observed in central Au + Au collisions at these three energies. No significant energy dependence of nuclear modification factors is found within uncertainties. The measured nuclear modification factors can be described by model calculations that take into account both suppression of direct J/ψ production due to the color screening effect and J/ψ regeneration from recombination of uncorrelated charm–anticharm quark pairs.
Circulating Fibrocytes, their role in renal fibrosis and molecular pathways involved. Possible biomarkers of fibrogenesis in chronic kidney disease
Creators: name: Fici, Pietro <1984>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2014
Subjects: MED/14 Nefrologia

description: Circulating Fibrocytes (CFs) are bone marrow-derived mesenchymal progenitor cells that express a similar pattern of surface markers related to leukocytes, hematopoietic progenitor cells and fibroblasts. CFs precursor display an ability to differentiate into fibroblasts and 
Myofibroblasts, as well as adipocytes.
Fibrocytes have been shown to contribute to tissue fibrosis in the end-stage renal disease (ESRD), as well as in other fibrotic diseases, leading to fibrogenic process in other organs including lung, cardiac, gut and liver. This evidence has been confirmed by several experimental proofs in mice models of kidney injury.
In the present study, we developed a protocol for the study of CFs, by using peripheral blood monocytes cells (PBMCs) samples collected from healthy human volunteers.
Thanks to a flow cytometry method, in vitro culture assays and the gene expression assays, we are able to study and characterize this CFs population. Moreover, results confirmed that these approaches are reliable and reproducible for the investigation of the circulating fibrocytes population in whole blood samples. 
Our final aim is to confirm the presence of a correlation between the renal fibrosis progression, and the different circulating fibrocyte levels in Chronic Kidney Disease (CKD) patients. Thanks to a protocol study presented and accepted by the Ethic Committee we are continuing the study of CFs induction in a cohort of sixty patients affected by CKD, divided in three distinct groups for different glomerular filtration rate (GFR) levels, plus a control group of thirty healthy subjects. Ongoing experiments will determine whether  circulating fibrocytes represent novel biomarkers for the study of CKD progression, in the early and late phases of this disease.
A mapping from the unitary to doubly stochastic matrices and symbols on a finite set
Creators: name: Karabegov, Alexander V.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Algebra (math.QA)
subject: FOS: Mathematics
subject: 53A07

description: We prove that the mapping from the unitary to the doubly stochastic matrices that maps a unitary matrix (u_{kl}) to the doubly stochastic matrix (|u_{kl}|^2) is a submersion for almost all unitary matrices. The proof uses the framework of operator symbols on a finite set. We give detailed proofs of the results announced in our earlier preprint.
description: 13 pages
Gauge effects in bound-bound Rydberg-transition matrix elements
Creators: name: Duspayev, Alisher
name: Raithel, Georg
Publisher: name: arXiv
Year: 2021
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Accurate data on electric-dipole transition matrix elements (EDTMs) for bound-bound Rydberg-atom transitions become increasingly important in science and technology. Here we compute radial EDTMs of rubidium using the length, velocity and acceleration gauges for electric-dipole-allowed transitions between states with principal and angular-momentum quantum numbers ranging from 15 to 100. Wave-functions are computed based upon model potentials from Marinescu et al., Phys. Rev. A {\bf{49}}, 982 (1994). Length-gauge EDTMs, often used for low-$\ell$ transitions, are found to deviate from the fundamentally more accurate velocity-gauge EDTMs by relative amounts of up to $\sim 10^{-3}$. We discuss the physical reasons for the observed gauge differences, explain the conditions for applicability of the velocity and length gauges for different transition series, and present a decision tree of how to choose EDTMs. Implications for contemporary Rydberg-atom applications are discussed.
description: 7 pages, 3 figures
Dijet imbalance measurements in Au+Au and pp collisions at sNN =200 GeV at STAR
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: STAR Collaboration

description: © 2017 American Physical Society. We report the first dijet transverse momentum asymmetry measurements from Au+Au and pp collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2 GeV/c display a significantly higher momentum imbalance in heavy-ion collisions than in the pp reference. When reexamined with correlated soft particles included, we observe that these dijets then exhibit a unique new feature - momentum balance is restored to that observed in pp for a jet resolution parameter of R=0.4, while rebalancing is not attained with a smaller value of R=0.2.
Novel chromium carbonyl complexes of dihydropyridines and their application to the synthesis of dehydrosecodine
Creators: name: Ridaura-Sanz, Vincente Ernesto
Publisher: name: University of British Columbia
Year: 2010

description: The work presented in this thesis is aimed at the total synthesis of 14,21-dehydrosecodine (1). This substance is an indole derivative with reactive substituents at position 2 (an acrylic ester segment) and 3 (a 1,6-dihydropyridine system). The stabilization of the latter involved the generation of chromium carbonyl complexes employing trisacetonitriletricarbonylchromium (0) as the reagent with appropriate synthetic indole derivatives. In order to develop the required methodology for the preparation of the above complexes, the initial experiments employed simple dihydropyridine systems. Thus, when N-methyl-3-ethyl pyridinium iodide (4_1) was treated with NaBH^ in a two-phase system (ether - water), N-methyl-3-ethyl-1,2-dihydropyridine (46_) was obtained. When this compound was treated with the above complexing agent a mixture (ratio 1:2) of (N-methyl-3-ethyl-l,2-dihydropyridine) tricarbonylchromium (0) (4_3) and (N-methyl-3-ethyl-l, 6-dihydropyridine) tricarbonylchromium (0) (4_4) was obtained. Thermal isomerization of this mixture in refluxing cyclo-hexane afforded a 1 : 1 ratio of (4_3) and (4_4) . Liberation of the organic ligand could be achieved by stirring (43) and/or (4_4) with pyridine. The above strategy was applied to the indole intermediate, N-(2-carbomethoxymethyltryptophyl)-3-ethylpyridinium per-chlorate (_36) but only a low yield (2%) of the desired chromium complexes was obtained. These results prompted a change in the original synthetic strategy and a new approach was initiated by other coworkers in this laboratory. Some studies with the novel system (4_6) were conducted as they relate to position of alkylation. It was shown that (46) undergoes reaction with benzyl bromide to afford the 5-substituted derivative.
Stellar Velocity Distribution in Galactic Disks
Creators: name: Theis, Christian
name: Vorobyov, Eduard
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present numerical studies of the properties of the stellar velocity distribution in galactic disks which have developed a saturated, two-armed spiral structure. In previous papers we used the Boltzmann moment equations (BME) up to second order for our studies of the velocity structure in self-gravitating stellar disks. A key assumption of our BME approach is the zero-heat flux approximation, i.e. the neglection of third order velocity terms. We tested this assumption by performing test particle simulations for stars in a disk galaxy subject to a rotating spiral perturbation. As a result we corroborated qualitatively the complex velocity structure found in the BME approach. It turned out that an equilibrium configuration in velocity space is only slowly established on a typical timescale of 5 Gyrs or more. Since many dynamical processes in galaxies (like the growth of spirals or bars)act on shorter timescales, pure equilibrium models might not be fully appropriate for a detailed comparison with observations like the local Galactic velocity distribution. Third order velocity moments were typically small and uncorrelated over almost all of the disk with the exception of the 4:1 resonance region (UHR). Near the UHR (normalized) fourth and fifth order velocity moments are still of the same order as the second and third order terms. Thus, at the UHR higher order terms are not negligible.
description: 8 pages, 3 figures, to appear in the Proceedings of "Chaos in Astronomy", Athens, G. Contopoulos & P.A. Patsis (eds.)
If you like C/O variations, you should have put a ring on it
Creators: name: van der Marel, Nienke
name: Bosman, Arthur
name: Krijt, Sebastiaan
name: Mulders, Gijs D.
name: Bergner, Jennifer B.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The C/O-ratio as traced with C$_2$H emission in protoplanetary disks is fundamental for constraining the formation mechanisms of exoplanets and our understanding of volatile depletion in disks, but current C$_2$H observations show an apparent bimodal distribution which is not well understood, indicating that the C/O distribution is not described by a simple radial dependence. The transport of icy pebbles has been suggested to alter the local elemental abundances in protoplanetary disks, through settling, drift and trapping in pressure bumps resulting in a depletion of volatiles in the surface and an increase of the elemental C/O. We combine all disks with spatially resolved ALMA C$_2$H observations with high-resolution continuum images and constraints on the CO snowline to determine if the C$_2$H emission is indeed related to the location of the icy pebbles. We report a possible correlation between the presence of a significant CO-icy dust reservoir and high C$_2$H emission, which is only found in disks with dust rings outside the CO snowline. In contrast, compact dust disks (without pressure bumps) and warm transition disks (with their dust ring inside the CO snowline) are not detected in C$_2$H, suggesting that such disks may never have contained a significant CO ice reservoir. This correlation provides evidence for the regulation of the C/O profile by the complex interplay of CO snowline and pressure bump locations in the disk. These results demonstrate the importance of including dust transport in chemical disk models, for a proper interpretation of exoplanet atmospheric compositions, and a better understanding of volatile depletion in disks, in particular the use of CO isotopologues to determine gas surface densities.
description: Accepted by A&A Letters. 5 pages, 2 figures, plus appendix (5 pages, 4 figures)
A brief note on the spectrum of the basic Dirac operator
Creators: name: Habib, Georges
name: Richardson, Ken
Publisher: name: arXiv
Year: 2008
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics

description: In this paper, we prove the invariance of the spectrum of the basic Dirac operator defined on a Riemannian foliation $(M,\mathcal{F})$ with respect to a change of bundle-like metric. We then establish new estimates for its eigenvalues on spin flows in terms of the O'Neill tensor and the first eigenvalue of the Dirac operator on $M$. We discuss examples and also define a new version of the basic Laplacian whose spectrum does not depend on the choice of bundle-like metric.
Nucleon electromagnetic form factors using lattice simulations at the physical point
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: hep-lat

description: © 2017 American Physical Society. We present results for the nucleon electromagnetic form factors using an ensemble of maximally twisted mass clover-improved fermions with pion mass of about 130 MeV. We use multiple sink-source separations and three analysis methods to probe ground-state dominance. We evaluate both the connected and disconnected contributions to the nucleon matrix elements. We find that the disconnected quark loop contributions to the isoscalar matrix elements are small, giving an upper bound of up to 2% of the connected and smaller than its statistical error. We present results for the isovector and isoscalar electric and magnetic Sachs form factors and the corresponding proton and neutron form factors. By fitting the momentum dependence of the form factors to a dipole form or to the z expansion, we extract the nucleon electric and magnetic radii, as well as the magnetic moment. We compare our results to experiment as well as to other recent lattice QCD calculations.
Handling Imbalanced Datasets Through Optimum-Path Forest
Creators: name: Passos, Leandro Aparecido
name: Jodas, Danilo S.
name: Ribeiro, Luiz C. F.
name: Akio, Marco
name: de Souza, Andre Nunes
name: Papa, João Paulo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: In the last decade, machine learning-based approaches became capable of performing a wide range of complex tasks sometimes better than humans, demanding a fraction of the time. Such an advance is partially due to the exponential growth in the amount of data available, which makes it possible to extract trustworthy real-world information from them. However, such data is generally imbalanced since some phenomena are more likely than others. Such a behavior yields considerable influence on the machine learning model's performance since it becomes biased on the more frequent data it receives. Despite the considerable amount of machine learning methods, a graph-based approach has attracted considerable notoriety due to the outstanding performance over many applications, i.e., the Optimum-Path Forest (OPF). In this paper, we propose three OPF-based strategies to deal with the imbalance problem: the $\text{O}^2$PF and the OPF-US, which are novel approaches for oversampling and undersampling, respectively, as well as a hybrid strategy combining both approaches. The paper also introduces a set of variants concerning the strategies mentioned above. Results compared against several state-of-the-art techniques over public and private datasets confirm the robustness of the proposed approaches.
Generalized TMDs and the exclusive double Drell–Yan process
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: hep-ph
hep-ex
nucl-ex

description: © 2017 The Authors Generalized transverse momentum dependent parton distributions (GTMDs) are the most general parton correlation functions of hadrons. By considering the exclusive double Drell–Yan process it is shown for the first time how quark GTMDs can be measured. Specific GTMDs can be addressed by means of polarization observables.
Post-explosion evolution of core-collapse supernovae
Creators: name: Witt, M.
name: Psaltis, A.
name: Yasin, H.
name: Horn, C.
name: Reichert, M.
name: Kuroda, T.
name: Obergaulinger, M.
name: Couch, S. M.
name: Arcones, A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We investigate the post-explosion phase in core-collapse supernovae with 2D hydrodynamical simulations and a simple neutrino treatment. The latter allows us to perform 46 simulations and follow the evolution of the 32 successful explosions during several seconds. We present a broad study based on three progenitors (11.2 $M_\odot$, 15 $M_\odot$, and 27 $M_\odot$), different neutrino-heating efficiencies, and various rotation rates. We show that the first seconds after shock revival determine the final explosion energy, remnant mass, and properties of ejected matter. Our results suggest that a continued mass accretion increases the explosion energy even at late times. We link the late-time mass accretion to initial conditions such as rotation strength and shock deformation at explosion time. Only some of our simulations develop a neutrino-driven wind that survives for several seconds. This indicates that neutrino-driven winds are not a standard feature expected after every successful explosion. Even if our neutrino treatment is simple, we estimate the nucleosynthesis of the exploding models for the 15 $M_\odot$ progenitor after correcting the neutrino energies and luminosities to get a more realistic electron fraction.
description: 16 pages, 15 figures, submitted to ApJ
Asymptotic and finite-sample properties of estimators based on stochastic gradients
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: Stochastic approximation
implicit updates
asymptotic variance
generalized linear models
Cox proportional hazards
M-estimation
maximum likelihood
exponential family
statistical efficiency
numerical stability

description: © 2017 Institute of Mathematical Statistics. Stochastic gradient descent procedures have gained popularity for parameter estimation from large data sets. However, their statistical properties are not well understood, in theory. And in practice, avoiding numerical instability requires careful tuning of key parameters. Here, we introduce implicit stochastic gradient descent procedures, which involve parameter updates that are implicitly defined. Intuitively, implicit updates shrink standard stochastic gradient descent updates. The amount of shrinkage depends on the observed Fisher information matrix, which does not need to be explicitly computed; thus, implicit procedures increase stability without increasing the computational burden. Our theoretical analysis provides the first full characterization of the asymptotic behavior of both standard and implicit stochastic gradient descent-based estimators, including finite-sample error bounds. Importantly, analytical expressions for the variances of these stochastic gradient-based estimators reveal their exact loss of efficiency. We also develop new algorithms to compute implicit stochastic gradient descent-based estimators for generalized linear models, Cox proportional hazards, M-estimators, in practice, and perform extensive experiments. Our results suggest that implicit stochastic gradient descent procedures are poised to become a workhorse for approximate inference from large data sets.
Comparative first-principles studies of prototypical ferroelectric materials by LDA, GGA, and SCAN meta-GGA
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: cond-mat.mtrl-sci

description: © 2017 American Physical Society. Originating from a broken spatial inversion symmetry, ferroelectricity is a functionality of materials with an electric dipole that can be switched by external electric fields. Spontaneous polarization is a crucial ferroelectric property, and its amplitude is determined by the strength of polar structural distortions. Density functional theory (DFT) is one of the most widely used theoretical methods to study ferroelectric properties, yet it is limited by the levels of approximations in electron exchange-correlation. On the one hand, the local density approximation (LDA) is considered to be more accurate for the conventional perovskite ferroelectrics such as BaTiO3 and PbTiO3 than the generalized gradient approximation (GGA), which suffers from the so-called super-tetragonality error. On the other hand, GGA is more suitable for hydrogen-bonded ferroelectrics than LDA, which largely overestimates the strength of hydrogen bonding in general. We show here that the recently developed general-purpose strongly constrained and appropriately normed (SCAN) meta-GGA functional significantly improves over the traditional LDA/GGA for structural, electric, and energetic properties of diversely bonded ferroelectric materials with a comparable computational effort and thus enhances largely the predictive power of DFT in studies of ferroelectric materials. We also address the observed system-dependent performances of LDA and GGA for ferroelectrics from a chemical bonding point of view.
A high performance liquid chromatographic study of post-stress isoflavonoid accumulation in Phaseolus Vulgaris and Pisum sativum
Creators: name: Carlson, Robert Eric
Publisher: name: University of British Columbia
Year: 2010

description: It has been observed in some plants that their post-infectional response to a potential pathogen leads to the synthesis and accumulation of compounds which may be significant in the processes of disease resistance. Consequently, a high performance liquid chromatographic procedure has been developed which will separate complex mixtures of Phaseolus vulgaris (green bean) and Pi sum sativum (garden pea) iso-flavonoids to give a chromatographic fingerprint of the post-stress metabolic response of these plants. This system has been used to determine the time course of the accumulation of the major de novo fungitoxic metabolites (phytoalexins) of abiotically stressed plants. These accumulation rate studies represent one of the most significant applications of the HPLC procedure because the quantification of a selected number of components of a mixture by other chromatographic methods can be, at best, tedious. The HPLC procedure has also been applied to the characterization of a number of other post-stress metabolites from P_. sativum. This study led to the identification of a previously unreported 2'-methoxychalcone (4,4'-dihydroxy-2'-methoxychalcone) and its benzylstyrene analogue (4-hydroxy-(4'-hydroxy-2'-methoxybenzyl)styrene) as well as a number of compounds which have been observed from other plant sources. The characterization of benzylstyrenes from P. sativum is particularly interesting because until now these compounds have only been described from heartwoods. Consequently, their identification as de novo metabolites will allow an in vivo investigation into their biosynthesis and potential role in disease resistance. To facilitate further studies on the chemistry and biochemistry of these compounds their MS, NMR and UV properties, as they pertain to the identification of structure, have been determined. A final aspect of this study was the qualitative evaluation of the response of P. sativum to a pathogenic and a non-pathogenic fungus. These results illustrated that the plant's net response to the two fungi was similar. However, a more important aspect of the study was its demonstration that the HPLC procedure could be used to determine the effects of in vivo fungal metabolism on the plant's accumulation of isoflavonoids.
Updated lattice results for parton distributions
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: hep-lat
hep-ph

description: © 2017 American Physical Society. We provide an analysis of the x dependence of the bare unpolarized, helicity, and transversity isovector parton distribution functions (PDFs) from lattice calculations employing (maximally) twisted mass fermions. The x dependence of the calculated PDFs resembles the one of the phenomenological parameterizations, a feature that makes this approach very promising. Furthermore, we apply momentum smearing for the relevant matrix elements to compute the lattice PDFs and find a large improvement factor when compared to conventional Gaussian smearing. This allows us to extend the lattice computation of the distributions to higher values of the nucleon momentum, which is essential for the prospects of a reliable extraction of the PDFs in the future.
Privacy Impact Assessment: Comparing methodologies with a focus on practicality
Creators: name: Bisztray, Tamas
name: Gruschka, Nils
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cryptography and Security (cs.CR)
subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: Privacy and data protection have become more and more important in recent years since an increasing number of enterprises and startups are harvesting personal data as a part of their business model. One central requirement of the GDPR is the implementation of a data protection impact assessment for privacy critical systems. However, the law does not dictate or recommend the use of any particular framework. In this paper we compare different data protection impact assessment frameworks. We have developed a comparison and evaluation methodology and applied this to three popular impact assessment frameworks. The result of this comparison shows the weaknesses and strengths, but also clearly indicates that none of the tested frameworks fulfill all desired properties. Thus, the development of a new or improved data protection impact assessment framework is an important open issue for future work, especially for sector specific applications.
New Developments in MadGraph/MadEvent
Creators: name: Alwall, Johan
name: Artoisenet, Pierre
name: de Visscher, Simon
name: Duhr, Claude
name: Frederix, Rikkert
name: Herquet, Michel
name: Mattelaer, Olivier
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We here present some recent developments of MadGraph/MadEvent since the latest published version, 4.0. These developments include: Jet matching with Pythia parton showers for both Standard Model and Beyond the Standard Model processes, decay chain functionality, decay width calculation and decay simulation, process generation for the Grid, a package for calculation of quarkonium amplitudes, calculation of Matrix Element weights for experimental events, automatic dipole subtraction for next-to-leading order calculations, and an interface to FeynRules, a package for automatic calculation of Feynman rules and model files from the Lagrangian of any New Physics model.
description: 6 pages, 3 figures. Plenary talk given at SUSY08, Seoul, South Korea, June 2008. To appear in the proceedings
First physics results at the physical pion mass from Nf=2 Wilson twisted mass fermions at maximal twist
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2017
Subjects: hep-lat

description: © 2017 American Physical Society. We present physics results from simulations of QCD using Nf=2 dynamical Wilson twisted mass fermions at the physical value of the pion mass. These simulations are enabled by the addition of the clover term to the twisted mass quark action. We show evidence that compared to previous simulations without this term, the pion mass splitting due to isospin breaking is almost completely eliminated. Using this new action, we compute the masses and decay constants of pseudoscalar mesons involving the dynamical up and down as well as valence strange and charm quarks at one value of the lattice spacing, a≈0.09 fm. Further, we determine renormalized quark masses as well as their scale-independent ratios, in excellent agreement with other lattice determinations in the continuum limit. In the baryon sector, we show that the nucleon mass is compatible with its physical value and that the masses of the Δ baryons do not show any sign of isospin breaking. Finally, we compute the electron, muon and tau lepton anomalous magnetic moments and show the results to be consistent with extrapolations of older ETMC data to the continuum and physical pion mass limits. We mostly find remarkably good agreement with phenomenology, even though we cannot take the continuum and thermodynamic limits.