cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Multi-wavelength study of TeV blazar 1ES 1218+304 using gamma-ray, X-ray and optical observations
Creators: name: Diwan, Rishank
name: Prince, Raj
name: Agarwal, Aditi
name: Bose, Debanjan
name: Majumdar, Pratik
name: Özdönmez, Aykut
name: Chandra, Sunil
name: Khatoon, Rukaiya
name: Ege, Ergün
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report the multi-wavelength study for a high-synchrotron-peaked BL Lac 1ES 1218+304 using near-simultaneous data obtained during the period from January 1, 2018, to May 31, 2021 (MJD 58119-59365) from various instruments including Fermi-LAT, Swift-XRT, AstroSat, and optical from Swift-UVOT $\&$ TUBITAK observatory in Turkey. The source was reported to be flaring in TeV $γ$-ray band during 2019, but no significant variation is observed with Fermi-LAT. A sub-hour variability is seen in the SXT light curve, suggesting a compact emission region for their variability. However, hour scale variability is observed in the $γ$-ray light curve. A "softer-when-brighter" trend is observed in $γ$-rays, and an opposite trend is seen in X-rays suggesting both emissions are produced via two different processes as expected from an HBL source. We have chosen the two epochs in January 2019 to study and compare their physical parameters. A joint fit of SXT and LAXPC provides a constraint on the synchrotron peak, roughly estimated to be $\sim$1.6 keV. A clear shift in the synchrotron peak is observed from $\sim$1 keV to above 10 keV revealing its extreme nature or behaving like an EHBL-type source. The optical observation provides color-index variation as "blue-when-brighter". The broadband SED is fitted with a single-zone SSC model, and their parameters are discussed in the context of a TeV blazar and the possible mechanism behind the broadband emission.
description: 13 pages, 10 figures, 5 tables, Accepted for publication in MNRAS
Measurement of energy differential spectrum of cosmic-ray muons below 400 MeV
Creators: name: Sato, Hikaru
name: Kin, Tadahiro
name: Giammanco, Andrea
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: Recent applications of cosmic-ray muons require accurate modeling of their flux at low-energy. However, no measurement has been reported below 400 MeV. Therefore, we developed a full-absorption muon energy spectrometer to obtain energy differential flux below 400 MeV. Because our main detector can measure muon energies below 75 MeV, an energy degradation method is adopted (using 5- and 20-cm thick lead blocks) to shift the sensitive energy range. Three measurements were performed (in the normal mode and the two energy degrading modes) for 10 and 11 days each. The measurement results were compared with an analytical cosmic-ray model, PARMA (the particle and heavy ion transport code system-based analytical radiation model in the atmosphere) and we found that the model can precisely predict the lower energy part of the flux.
description: 8 pages, 15 figures
Describing NMR chemical exchange by effective phase diffusion approach
Creators: name: Lin, Guoxing
Publisher: name: arXiv
Year: 2023
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: This paper proposes an effective phase diffusion method to analyze chemical exchange in nuclear magnetic resonance (NMR). The chemical exchange involves spin jumps around different sites where the spin angular frequencies vary, which leads to a random phase walk viewed from the rotating frame reference. Therefore, the random walk in phase space can be treated by the effective phase diffusion method. Both the coupled and uncoupled phase diffusions are considered; additionally, it includes normal diffusion as well as fractional diffusion. Based on these phase diffusion equations, the line shape of NMR exchange spectrum can be analyzed. By comparing these theoretical results with the conventional theory, this phase diffusion approach works for fast exchange, ranging from slightly faster than intermediate exchange to very fast exchange. For normal diffusion models, the theoretically predicted curves agree with those predicted from traditional models in the literature, and the characteristic exchange time obtained from phase diffusion with a fixed jump time is the same as that obtained from the conventional model. However, the phase diffusion with a monoexponential time distribution gives a characteristic exchange time constant which is half of that obtained from the traditional model. Additionally, the fractional diffusion obtains a significantly different line shape than that predicted based on normal diffusion.
description: 20 pages, 4 figures
Solvable Model of a Mixture of Bose-Einstein Condensates
Creators: name: Klaiman, Shachar
name: Streltsov, Alexej I.
name: Alon, Ofir E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A mixture of two kinds of identical bosons held in a harmonic potential and interacting by harmonic particle-particle interactions is discussed. This is an exactly-solvable model of a mixture of two trapped Bose-Einstein condensates which allows us to examine analytically various properties. Generalizing the treatment in [Cohen and Lee, J. Math. Phys. {\bf 26}, 3105 (1985)], closed form expressions for the ground-state energy, wave-function, and lowest-order densities are obtained and analyzed for attractive and repulsive intra-species and inter-species particle-particle interactions. A particular mean-field solution of the corresponding Gross-Pitaevskii theory is also found analytically. This allows us to compare properties of the mixture at the exact, many-body and mean-field levels, both for finite systems and at the limit of an infinite number of particles. We hereby prove that the exact ground-state energy and lowest-order intra-species and inter-species densities converge at the infinite-particle limit (when the products of the number of particles times the intra-species and inter-species interaction strengths are held fixed) to the results of the Gross-Pitaevskii theory for the mixture. Finally and on the other end, the separability of the mixture's center-of-mass coordinate is used to show that the Gross-Pitaevskii theory for mixtures is unable to describe the variance of many-particle operators in the mixture, even in the infinite-particle limit. Our analytical results show that many-body correlations exist in a mixture of Bose-Einstein condensates made of any number of particles. Implications are briefly discussed.
description: 26 pages
Spectral Form Factor in Sparse SYK Models
Creators: name: Cáceres, Elena
name: Misobuchi, Anderson
name: Raz, Amir
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We investigate the spectral form factor of the sparse Sachdev-Ye-Kitaev model. We use numerical methods to establish that at intermediate times the connected part of the spectral form factor is the dominant one. These connected contributions arise from fluctuations around the disconnected geometry, not from a new saddle point. A similar effect was previously conjectured in SYK but required a value of $N$ out of reach of current numerical simulations.
description: 21 pages, 11 figures V2: Minor edits and lower resolution figures
Polarised antibranes from Smarr relations
Creators: name: Cohen-Maldonado, Diego
name: Diaz, Juan
name: Gautason, Fridrik Freyr
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the backreaction of smeared and localised anti M2-branes placed at the tip of the CGLP background. To this end we derive a Smarr relation for backreacted antibranes at zero and finite temperature. For extremal antibranes we show that if smeared they cannot have regular horizons, whereas localised M2-branes can potentially be regular when polarised into M5-branes, in agreement with the probe result of Klebanov and Pufu. We further discuss antibranes at finite temperature and argue that localised antibrane solutions with regular horizons are not excluded.
description: 26 pages, 3 figures
Strongly enhanced Rashba splittings in oxide heterostructure: a tantalite monolayer on BaHfO$_3$
Creators: name: Kim, Minsung
name: Ihm, Jisoon
name: Chung, Suk Bum
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: In the two-dimensional electron gas (2DEG) emerging at the transition metal oxide surface and interface, it has been pointed out that the Rashba spin-orbit interaction, the momentum-dependent spin splitting due to broken inversion symmetry and atomic spin-orbit coupling, can have profound effects on electronic ordering in the spin, orbit, and charge channels, and may help give rise to exotic phenomena such as ferromagnetism-superconductivity coexistence and topological superconductivity. Although a large Rashba splitting is expected to improve experimental accessibility of such phenomena, it has not been understood how we can maximally enhance this splitting. Here, we present a promising route to realize significant Rashba-type band splitting using a thin film heterostructure. Based on first-principles methods and analytic model analyses, a tantalate monolayer on BaHfO$_3$ is shown to host two-dimensional bands originating from Ta $t_{2g}$ states with strong Rashba spin splittings - up to nearly 10% of the bandwidth - at both the band minima and saddle points due to the maximal breaking of the inversion symmetry. Such 2DEG band structure makes this oxide heterostructure a promising platform for realizing both a topological superconductor which hosts Majorana fermions and the electron correlation physics with strong spin-orbit coupling.
description: 11 pages, 7 figures
Concurrent kilovoltage CBCT imaging and megavoltage beam delivery: Suppression of cross-scatter with 2D antiscatter grids and grid-based scatter sampling
Creators: name: Bayat, Farhang
name: Eldib, Mohamed Elsayed
name: Kavanagh, Brian
name: Miften, Moyed
name: Altunbas, Cem
Publisher: name: arXiv
Year: 2022
Subjects: subject: Medical Physics (physics.med-ph)
subject: FOS: Physical sciences

description: The concept of using kilovoltage (kV) and megavoltage (MV) beams concurrently has potential applications in cone beam computed tomography (CBCT) guided radiation therapy, such as single breath hold scans, metal artifact reduction, and simultaneous imaging during MV treatment delivery. However, MV cross-scatter generated during MV beam delivery degrades CBCT image quality. To address this, a 2D antiscatter grid and cross scatter correction method were investigated. a 3D printed, tungsten 2D antiscatter grid prototype was utilized to reduce MV cross-scatter fluence in kV projections during concurrent MV beam delivery. Remaining cross-scatter was corrected by using the 2D grid itself as a cross-scatter intensity sampling device, referred as Grid-based Scatter Sampling. To test this approach, kV CBCT acquisitions were performed while delivering 6 and 10 MV beams, mimicking high dose rate treatment delivery scenarios. MV cross-scatter suppression performance of the proposed approach was evaluated in projections and CBCT images of phantoms. 2D grid reduced the intensity of MV cross-scatter in kV projections by a factor of 3 on the average. Remaining MV cross-scatter estimated by Grid-based Scatter Sampling was within 7% of measured reference intensity values. CBCT image quality was improved substantially during concurrent kV-MV beam delivery. Median Hounsfield Unit (HU) inaccuracy was up to 191 HU without our methods, and it was reduced to 3 HU with our 2D grid and scatter correction approach. Our methods provided a factor of 2-6 improvement in contrast-to-ratio. Results indicate that our approach can successfully minimize the effects of high energy cross-scatter in concurrent kV CBCT imaging and megavoltage treatment delivery.
A theoretical perspective on the formation and fragmentation of protostellar discs
Creators: name: Whitworth, A. P.
name: Lomax, O. D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We discuss the factors influencing the formation and gravitational fragmentation of protostellar discs. We start with a review of how observations of prestellar cores can be analysed statistically to yield plausible initial conditions for simulations of their subsequent collapse. Simulations based on these initial conditions show that, despite the low levels of turbulence in prestellar cores, they deliver primary protostars and associated discs which are routinely subject to stochastic impulsive perturbations; consequently misalignment of the spins and orbits of protostars are common. Also, the simulations produce protostars that collectively have a mass function and binary statistics matching those observed in nearby star formation regions, but only if a significant fraction of the turbulent energy in the core is solenoidal, and accretion onto the primary protostar is episodic with a duty cycle > 3000 yr. Under this circumstance a core typically spawns between 4 and 5 protostars, with high efficiency, and the lower-mass protostars are mainly formed by disc fragmentation. The requirement that a proto-fragment in a disc lose thermal energy on a dynamical timescale dictates that {\bf there is a sweet spot for} disc fragmentation at radii 70 AU < R < 100 AU and temperatures 10 K < T < 20 K, and this might explain the Brown Dwarf Desert.
description: 12 pages, 3 figures, published in PASA
Time dependent field correlators from holographic EPR pairs
Creators: name: Kawamoto, Shoichi
name: Lee, Da-Shin
name: Yeh, Chen-Pin
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the correlators of the fields that couple to the quark and anti-quark EPR pair in the super Yang-Mills theory using the holographic description, which is a string in AdS space with its two ends anchoring on the boundaries. We consider the cases that the endpoints of the string are static and that the endpoints are uniformly accelerated in opposite directions where the exact solutions for the string's profiles are available. In both cases, the two-point correlators of the boundary field, described by the linearized perturbations in the worldsheet, can also be derived exactly where we obtain the all-time evolution of the correlators. In the case of the accelerating string, the induced geometry on the string worldsheet has the causal structure of a two-sided AdS black hole with a wormhole connecting two causally disconnected boundaries, which can be a realization of the ER=EPR conjecture. We find that causality plays a crucial role in determining the nature of the dispersion relation of the particle and the feature of the induced mutual interaction between two particles from the field. In the case that two boundaries of the worldsheet are causally disconnected, the induced effect from the field gives the dissipative dynamics of each particle with no dependence on the distance between two particles, and the induced mutual coupling between them vanishes in the late times, following a power law. When two ends are causally connected, the induced dispersion relation becomes non-dissipative in the late times. Here, we will also comment on the implications of our findings to the entangled particle dynamics and the ER=EPR conjecture.
description: published version (v2)
Propagation of Linear Uncertainties through Multiline Thru-Reflect-Line Calibration
Creators: name: Hatab, Ziad
name: Gadringer, Michael Ernst
name: Bösch, Wolfgang
Publisher: name: arXiv
Year: 2023
Subjects: subject: Signal Processing (eess.SP)
subject: Applied Physics (physics.app-ph)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Physical sciences

description: This study proposes a linear approach for propagating uncertainties in the multiline thru-reflect-line (TRL) calibration method for vector network analyzers. The multiline TRL formulation we are proposing applies the law of uncertainty propagation as outlined in the ISO Guide to the Expression of Uncertainty in Measurement (GUM) to both measurement and model uncertainties. In addition, we conducted a Monte Carlo analysis using a combination of measured and synthetic data to model various uncertainties, such as additive noise, reflect asymmetry, line mismatch, and line length offset. The results of our linear uncertainty formulation demonstrate agreement with the Monte Carlo method and provide a more efficient means of assessing the uncertainty budget of the multiline TRL calibration.
description: GitHub: https://github.com/ZiadHatab/uncertainty-multiline-trl-calibration
Probing surface recombination velocities in semiconductors using two-photon microscopy
Creators: name: Gaury, Benoit
name: Haney, Paul
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The determination of minority-carrier lifetimes and surface recombination velocities is essential for the development of semiconductor technologies such as solar cells. The recent development of two-photon time-resolved microscopy allows for better measurements of bulk and subsurface interfaces properties. Here we analyze the diffusion problem related to this optical technique. Our three-dimensional treatment enables us to separate lifetime (recombination) from transport effects (diffusion) in the photoluminescence intensity. It also allows us to consider surface recombination occurring at a variety of geometries: a single plane (representing an isolated exposed or buried interface), two parallel planes (representing two inequivalent interfaces), and a spherical surface (representing the enclosing surface of a grain boundary). We provide fully analytical results and scalings directly amenable to data fitting, and apply those to experimental data collected on heteroepitaxial CdTe/ZnTe/Si.
description: 9 pages, 7 figures
An Approximate Algorithm for Maximum Inner Product Search over Streaming Sparse Vectors
Creators: name: Bruch, Sebastian
name: Nardini, Franco Maria
name: Ingber, Amir
name: Liberty, Edo
Publisher: name: arXiv
Year: 2023
Subjects: subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: Maximum Inner Product Search or top-k retrieval on sparse vectors is well-understood in information retrieval, with a number of mature algorithms that solve it exactly. However, all existing algorithms are tailored to text and frequency-based similarity measures. To achieve optimal memory footprint and query latency, they rely on the near stationarity of documents and on laws governing natural languages. We consider, instead, a setup in which collections are streaming -- necessitating dynamic indexing -- and where indexing and retrieval must work with arbitrarily distributed real-valued vectors. As we show, existing algorithms are no longer competitive in this setup, even against naive solutions. We investigate this gap and present a novel approximate solution, called Sinnamon, that can efficiently retrieve the top-k results for sparse real valued vectors drawn from arbitrary distributions. Notably, Sinnamon offers levers to trade-off memory consumption, latency, and accuracy, making the algorithm suitable for constrained applications and systems. We give theoretical results on the error introduced by the approximate nature of the algorithm, and present an empirical evaluation of its performance on two hardware platforms and synthetic and real-valued datasets. We conclude by laying out concrete directions for future research on this general top-k retrieval problem over sparse vectors.
Superfluid Phase Transition with Activated Velocity Fluctuations: Renormalization Group Approach
Creators: name: Dančo, M.
name: Hnatič, M.
name: Komarova, M. V.
name: Lučivjanský, T.
name: Nalimov, M. Yu.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A quantum field model that incorporates Bose-condensed systems near their phase transition into a superfluid phase and velocity fluctuations is proposed. The stochastic Navier-Stokes equation is used for a generation of the velocity fluctuations. As such this model generalizes model F of critical dynamics. The field-theoretic action is derived using the Martin-Siggia-Rose formalism and path integral approach. The regime of equilibrium fluctuations is analyzed within perturbative renormal- ization group method. The double $(ε,δ)$-expansion scheme is employed, where is a deviation from space dimension $4$ and $δ$ describes scaling of velocity fluctuations. The renormalization procedure is performed to the leading order. The main corollary gained from the analysis of the thermal equilibrium regime suggests that one-loop calculations of the presented models are not sufficient to make a definite conclusion about the stability of fixed points. We also show that critical exponents are drastically changed as a result of the turbulent background and critical fluctuations are in fact destroyed by the developed turbulence fluctuations. The scaling exponent of effective viscosity is calculated and agrees with expected value $4/3$.
Two-dimensional shaping of Solov'ev equilibrium with vacuum using external coils
Creators: name: Liu, Jiaxing
name: Zhu, Ping
name: Li, Haolong
Publisher: name: arXiv
Year: 2022
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: In this work, we demonstrate a method for constructing the Solov'ev equilibrium with any given 2D shape surrounded by a vacuum region using external poloidal field coils. The computational domain consists of two parts: the plasma region, where the solution is the same as the Solov'ev solution, and the vacuum region, where the magnetic field generated by external coils as well as plasma current is determined using the Green function method through a matching condition near the separatrix. However, the method is not limited to the Solov'ev equilibrium in particular. The accuracy, efficiency, and robustness of such a scheme suggest that this method may be applied to the 2D shaping of tokamak plasma with vacuum region using external coils in general.
Quenching of antihydrogen gravitational states by surface charges
Creators: name: Voronin, A. Yu.
name: Kupriyanova, E. A.
name: Lambrecht, A.
name: Nesvizhevsky, V. V.
name: Reynaud, S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study an effect of quenching of antihydrogen quantum states near material surface in the gravitational field of the Earth by local charges randomly distributed along the mirror surface. The quenching mechanism reduces the quantum reflection probability because of additional atom-charge interaction and nonadiabatic transitions to excited gravitational states. Our approach is suitable for accounting for quenching caused by any kind of additional interaction with the characteristic range much smaller than the typical gravitational state wave-length.
Asymmetry and condition number of an elliptic-parabolic system for biological network formation
Creators: name: Astuto, Clarissa
name: Boffi, Daniele
name: Haskovec, Jan
name: Markowich, Peter
name: Russo, Giovanni
Publisher: name: arXiv
Year: 2023
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: We present results of numerical simulations of the tensor-valued elliptic-parabolic PDE model for biological network formation. The numerical method is based on a non-linear finite difference scheme on a uniform Cartesian grid in a 2D domain. The focus is on the impact of different discretization methods and choices of regularization parameters on the symmetry of the numerical solution. In particular, we show that using the symmetric alternating-direction implicit (ADI) method for time discretization helps preserve the symmetry of the solution, compared to the (non symmetric) ADI method. Moreover, we study the effect of regularization by isotropic background permeability $r>0$, showing that increased condition number of the elliptic problem due to decreasing value of $r$ leads to loss of symmetry. We show that in this case, neither the use of the symmetric ADI method preserves the symmetry of the solution. Finally, we perform numerical error analysis of our method making use of Wasserstein distance.
description: 16 pages, 6 figures, 2 tables
Regulation of KIT in spermatogenesis and hematopoiesis
Creators: name: Prabhu.., Sridurga Mithra
Publisher: name: Monash University
Year: 2021

description: This thesis was scanned from the print manuscript for digital preservation and is copyright the author.
 Researchers can access this thesis by asking their local university, institution or public library to
 make a request on their behalf. Monash staff and postgraduate students can use the link in the References field.
The charm-quark contribution to light-by-light scattering in the muon $(g-2)$ from lattice QCD
Creators: name: Chao, En-Hung
name: Hudspith, Renwick J.
name: Gérardin, Antoine
name: Green, Jeremy R.
name: Meyer, Harvey B.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We compute the hadronic light-by-light scattering contribution to the muon $g-2$ from the charm quark using lattice QCD. The calculation is performed on ensembles generated with dynamical $(u,d,s)$ quarks at the SU(3)$_{\rm f}$ symmetric point with degenerate pion and kaon masses of around 415 MeV. It includes the connected charm contribution, as well as the leading disconnected Wick contraction, involving the correlation between a charm and a light-quark loop. Cutoff effects turn out to be sizeable, which leads us to use lighter-than-physical charm masses, to employ a broad range of lattice spacings reaching down to 0.039 fm and to perform a combined charm-mass and continuum extrapolation. We use the $η_c$ meson to define the physical charm-mass point and obtain a final value of $a_μ^{\rm HLbL,c} = (2.8\pm 0.5) \times 10^{-11}$, whose uncertainty is dominated by the systematics of the extrapolation. Our result is consistent with the estimate based on a simple charm-quark loop, whilst being free of any perturbative scheme dependence on the charm mass. The mixed charm-light disconnected contraction contributes a small negative amount to the final value.
description: 21 pages, 8 figures, 9 tables
The nature of the late B-type stars HD 67044 and HD 42035
Creators: name: Monier, R.
name: Gebran, M.
name: Royer, F.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: While monitoring a sample of apparently slowly rotating superficially normal bright late B and early A stars in the northern hemisphere, we have discovered that HD 67044 and HD 42035, hitherto classified as normal late B-type stars, are actually respectively a new chemically peculiar star and a new spectroscopic binary containing a very slow rotator HD 42035 S with ultra-sharp lines (vsini = 3.7 km/s) and a fast rotator HD 42035 B with broad lines. The lines of Ti, Cr, Mn, Sr, Y, Zr and Ba are conspicuous features in the high resolution SOPHIE spectrum of HD 67044. The HgII line at 3983.93 A is also present as a weak feature. The composite spectrum of HD 42035 is characterised by very sharp lines formed in HD 42035 S superimposed onto the shallow and broad lines of HD 42035 B. These very sharp lines are mostly due to light elements from C to Ni, the only heavy species definitely present are Sr and Ba. Selected lines of 21 chemical elements from He up to Hg have been synthesized using model atmospheres computed with ATLAS9 and the spectrum synthesis code SYNSPEC48 including hyperfine structure of various isotopes when relevant. Abundances of these key elements have been derived HD 67044 and HD 42035 S. HD 67044 is found to have distinct enhancements of Ti, Cr, Mn, Sr, Y, Zr, Ba and Hg and underabundances in He, C, O, Ca and Sc which shows that this star is not a superficially normal late B-type star, but actually is a new CP star most likely of the HgMn type. HD 42035 S has provisional underabundances of the light elements from C to Ti and overabundances of heavier elements up to barium. More accurate fundamental parameters and abundances for HD 42035 S and HD 42035 B will be derived if we manage to disentangle their spectra. They will help clarify the status of the two components in this interesting new spectroscopic binary.
description: 30 pages, 4 figures, 2 tables, accepted in APSS. arXiv admin note: text overlap with arXiv:1504.02727
Performance, robustness and sensitivity analysis of the nonlinear tuned vibration absorber
Creators: name: Detroux, Thibaut
name: Habib, Giuseppe
name: Masset, Luc
name: Kerschen, Gaetan
Publisher: name: arXiv
Year: 2016
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: The nonlinear tuned vibration absorber (NLTVA) is a recently-developed nonlinear absorber which generalizes Den Hartog's equal peak method to nonlinear systems. If the purposeful introduction of nonlinearity can enhance system performance, it can also give rise to adverse dynamical phenomena, including detached resonance curves and quasiperiodic regimes of motion. Through the combination of numerical continuation of periodic solutions, bifurcation detection and tracking, and global analysis, the present study identifies boundaries in the NLTVA parameter space delimiting safe, unsafe and unacceptable operations. The sensitivity of these boundaries to uncertainty in the NLTVA parameters is also investigated.
description: Journal paper
Robust online active learning
Creators: name: Cacciarelli, Davide
name: Kulahci, Murat
name: Tyssedal, John Sølve
Publisher: name: arXiv
Year: 2023
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: In many industrial applications, obtaining labeled observations is not straightforward as it often requires the intervention of human experts or the use of expensive testing equipment. In these circumstances, active learning can be highly beneficial in suggesting the most informative data points to be used when fitting a model. Reducing the number of observations needed for model development alleviates both the computational burden required for training and the operational expenses related to labeling. Online active learning, in particular, is useful in high-volume production processes where the decision about the acquisition of the label for a data point needs to be taken within an extremely short time frame. However, despite the recent efforts to develop online active learning strategies, the behavior of these methods in the presence of outliers has not been thoroughly examined. In this work, we investigate the performance of online active linear regression in contaminated data streams. Our study shows that the currently available query strategies are prone to sample outliers, whose inclusion in the training set eventually degrades the predictive performance of the models. To address this issue, we propose a solution that bounds the search area of a conditional D-optimal algorithm and uses a robust estimator. Our approach strikes a balance between exploring unseen regions of the input space and protecting against outliers. Through numerical simulations, we show that the proposed method is effective in improving the performance of online active learning in the presence of outliers, thus expanding the potential applications of this powerful tool.
description: Published in Quality and Reliability Engineering International (2023)
Hybrid Quantum-Classical Hierarchy for Mitigation of Decoherence and Determination of Excited States
Creators: name: McClean, Jarrod R.
name: Schwartz, Mollie E.
name: Carter, Jonathan
name: de Jong, Wibe A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Using quantum devices supported by classical computational resources is a promising approach to quantum-enabled computation. One example of such a hybrid quantum-classical approach is the variational quantum eigensolver (VQE) built to utilize quantum resources for the solution of eigenvalue problems and optimizations with minimal coherence time requirements by leveraging classical computational resources. These algorithms have been placed among the candidates for first to achieve supremacy over classical computation. Here, we provide evidence for the conjecture that variational approaches can automatically suppress even non-systematic decoherence errors by introducing an exactly solvable channel model of variational state preparation. Moreover, we show how variational quantum-classical approaches fit in a more general hierarchy of measurement and classical computation that allows one to obtain increasingly accurate solutions with additional classical resources. We demonstrate numerically on a sample electronic system that this method both allows for the accurate determination of excited electronic states as well as reduces the impact of decoherence, without using any additional quantum coherence time or formal error correction codes.
Light propagating in a Born-Infeld background as seen by an accelerated observer
Creators: name: Guzman-Herrera, Elda
name: Breton, Nora
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the propagation of light in the Born-Infeld (BI) background as seen by an accelerated observer. In a Born-Infeld electromagnetic field, light trajectories are governed by the null geodesics of the effective optical metric. The accelerated observer is in a Rindler frame, a situation that, according to the Einstein Equivalence Principle, is equivalent to being in a uniform gravitational field. The phase velocity of light propagating through a purely magnetic or electric BI background is determined as measured by the Rindler observer. The BI field and the acceleration of the frame have opposite effects on the propagating light: while the intense electric or magnetic BI background slows down the velocity of light, in the accelerated frame light may exceed its velocity in vacuum. We consider light propagating parallel or transversal to the acceleration direction of the Rindler frame. The redshift of light pulses sent from one Rindler observer to another, in the BI background, is calculated as well.
description: 32 pages, 15 figures
Ultra-sensitive nanoscale magnetic field sensors based on resonant spin filtering
Creators: name: Sharma, Abhishek
name: Tulapurkar, Ashwin
name: Muralidharan, Bhaskaran
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Solid state magnetic field sensors based on magneto-resistance modulation find direct applications in communication devices, specifically in proximity detection, rotational reference detection and current sensing. In this work, we propose sensor structures based on the magneto-resistance physics of resonant spin-filtering and present device designs catered toward exceptional magnetic field sensing capabilities. Using the non-equilibrium Green's function spin transport formalism self consistently coupled to the Poisson's equation, we present highly-tunable pentalayer magnetic tunnel junction structures that are capable of exhibiting an ultra-high peak tunnel magneto resistance $(\approx 2500 \%$). We show how this translates to device designs featuring an ultra-high current sensitivity enhancement of over 300\% in comparison with typical trilayer MTJ sensors, and a wider tunable range of field sensitivity. We also demonstrate that a dynamic variation in sensor functionalities with the structural landscape enables a superior design flexibility over typical trilayer sensors. An optimal design exhibiting close to a 700\% sensitivity increase as a result of angle dependent spin filtering is then presented.This work sets a stage to engineer spintronic building blocks via the design of functional structures tailored to exhibit ultra-sensitive spin filtering.
description: 8 pages, 12 figures
A closer look to the sgoldstino interpretation of the diphoton excess
Creators: name: Baratella, P.
name: Elias-Miro, J.
name: Penedo, J.
name: Romanino, A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We revisit the sgoldstino interpretation of the diphoton excess in the context of gauge mediation. While the bound on the gluino mass might seem to make the sgoldstino contribution to the diphoton excess unobservable, we show that the interpretation is viable in a thin, near critical region of the parameter space. This regime gives rise to drastic departures from the standard gauge mediation picture. While the fermion messengers lie in the (10-100) TeV range, some scalar messengers are significantly lighter and are responsible for the sgoldstino production and decay. Their effective coupling to the sgoldstino is correspondingly enhanced, and a non-perturbative regime is triggered when light and heavy messenger masses differ by a factor $\sim4π$. We also comment on the possible role of an R-axion and on the possibility to decouple the sfermions in this context.
D6.9 INTEGRATION OF RESULTS: POLICYCLOUD COMPLETE ENVIRONMENT M36
Creators: name: Moutselos, Kostas
name: Michael, Panayotis
name: Moulos, Vrettos
name: Pavlatos, Christos
name: Koniaris, Marios
name: Tsanakas, Panagiotis
name: Kolaitis, Aggelos
name: Zaragoza, Jose María
name: Moatti, Yosef
name: Sanguino Gonzalez, Maria Angeles
name: Pontual, Ana Luiza
name: Milá, Miquel
name: Munné, Ricard
name: La Rocca, Giuseppe
name: Manias, George
name: Kiourtis, Athanasios
name: Maglogiannis, Ilias
name: Sgouros, Nikitas
name: Mavrogiorgou, Argyro
name: del Hoyo, Rafael
name: Theodosiou, Konstantinos
name: Ledakis, Giannis
name: Duzha, Armend
name: Baroni, Samuele
name: Nikolova, Petya
name: Yovkova, Iskra
name: Rodrigálvarez, Vega
Publisher: name: Zenodo
Year: 2022
Subjects: Policy Cloud
policymaking
data driven
policy management
big data
co-creation

description: This deliverable has been released in December 2022, at M36 of the project, and its main objective is to specify the final integration results between the PolicyCLOUD components. This deliverable will follow the methodology of D6.2 and D6.8 that were respectively submitted in M12 (December 2020) and M24 (December 2021) which have two main pillars: Define common practices for integration and validation of the outcomes of the project Detail the cloud environment the project will make use of to demonstrate the results Regarding the former, GitLab will be the base code repository for the project, where the project already owns an organizational account. Over GitLab [1], the trunk-based development branching policy has been applied, as we considered it the most suitable policy given the project characteristics. Also, GitLab’s issue reporting tool has been adopted, as it is fully integrated with GitLab’s features. The test bed to support the demonstrators has been deployed over EGI’s (EGI) infrastructure where flexibility is one of the critical features. This deliverable abstractly incorporates all the changes and implementations that WP2, WP3, WP4 and WP5 had made during the second year of the project. More details about the components and the actual implementation can be found in the related WP deliverables [7] [8] [9]. In detail, the schemas of the data have been finalized so the standard version that we defined initiated the data import to the repository of PolicyCLOUD. Moreover, the infrastructure (IaaS) and the platform deployment (PaaS/ Serverless) have been restructured and reshaped based on the latest needs of the components. EGI deployed the new flavour of PolicyCLOUD to the Openstack Infrastructure and IBM made the proper changes to the Openwhisk middleware for the serverless and other services. The related WP deliverables highlight detailed information and instructions for each component change that in total orchestrate the PolicyCLOUD engine.
description: This deliverable is submitted to the EC, not yet approved.
Frequency-Tunable Microwave Field Detection in an Atomic Vapor Cell
Creators: name: Horsley, Andrew
name: Treutlein, Philipp
Publisher: name: arXiv
Year: 2016
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Instrumentation and Detectors (physics.ins-det)
subject: Medical Physics (physics.med-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We use an atomic vapor cell as a frequency tunable microwave field detector operating at frequencies from GHz to tens of GHz. We detect microwave magnetic fields from 2.3 GHz to 26.4 GHz, and measure the amplitude of the sigma+ component of an 18 GHz microwave field. Our proof-of-principle demonstration represents a four orders of magnitude extension of the frequency tunable range of atomic magnetometers from their previous dc to several MHz range. When integrated with a high resolution microwave imaging system, this will allow for the complete reconstruction of the vector components of a microwave magnetic field and the relative phase between them. Potential applications include near-field characterisation of microwave circuitry and devices, and medical microwave sensing and imaging.
Light-cone distribution amplitudes of heavy mesons with QED effects
Creators: name: Beneke, Martin
name: Böer, Philipp
name: Toelstede, Jan-Niklas
name: Vos, Keri K.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We discuss the QED-generalized leading-twist light-cone distribution amplitudes of heavy mesons, that appear in QCD$\times$QED factorization theorems for exclusive two-body $B$ decays. In the presence of electrically charged particles, these functions should be more appropriately regarded as soft functions for heavy-meson decays into two back-to-back particles. In this paper, we derive the one-loop anomalous dimension of these soft functions and study their behaviour under renormalization-scale evolution, obtaining an exact solution in Laplace space. In addition, we provide numerical solutions for the soft functions and analytical solutions to all orders in the strong and to first order in the electromagnetic coupling. For the inverse (and inverse-logarithmic) moments, we obtain an all-order solution in both couplings. We further provide numerical estimates for QED corrections to the inverse moments.
description: 38 pages, 3 figures
Drag induced radiative energy loss of semi-hard heavy quarks
Creators: name: Abir, Raktim
name: Cao, Shanshan
name: Majumder, Abhijit
name: Qin, Guang-You
Publisher: name: arXiv
Year: 2016
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We revisited gluon bremsstrahlung off a heavy quark in nuclear matter within higher twist formalism. In this work, we demonstrate that, in addition to transverse momentum diffusion parameter ($\hat q$), the gluon emission spectrum for a heavy quark is quite sensitive to $\hat e$, which quantify the amount of light-cone drag experienced by a parton. This effect leads to an additional energy loss term for heavy-quarks. From heavy flavor suppression data in ultra-relativistic heavy-ion collisions one can now estimate the value of this sub-leading non-perturbative jet transport parameter ($\hat e$) from our results.
description: Talk given at Hard Probes 2016, based on arXiv:1506.08648
Hard X-ray Tail Discovered in the Clocked Burster GS 1826-238
Creators: name: Rodi, James
name: Jourdain, Elisabeth
name: Roques, Jean-Pierre
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The LMXB NS GS 1826-238 was discovered by Ginga in 1988 September. Due to the presence of quasi-periodicity in the type I X-ray burst rate, the source has been a frequent target of X-ray observations for almost 30 years. Though the bursts were too soft to be detected by INTEGRAL/SPI, the persistent emission from GS 1826-238 was detected over 150 keV during the ~10 years of observations. Spectral analysis found a significant high-energy excess above a Comptonization model that is well fit by a power law, indicating an additional spectral component. Most previously reported spectra with hard tails in LMXB NS have had an electron temperature of a few keV and a hard tail dominating above ~50 keV with an index of Γ~ 2-3. GS 1826-238 was found to have a markedly different spectrum with $ kT_e \sim 20 $ keV and a hard tail dominating above ~150 keV with an index of Γ~ 1.8, more similar to BHXRB. We report on our search for long-term spectral variability over the 25-370 keV energy range and on a comparison of the GS 1826-238 average spectrum to the spectra of other LMXB NS with hard tails.
Superfluid stiffness of a KTaO3-based two-dimensional electron gas
Creators: name: Mallik, S.
name: Ménard, G.
name: Saïz, G.
name: Witt, H.
name: Lesueur, J.
name: Gloter, A.
name: Benfatto, L.
name: Bibes, M.
name: Bergeal, N.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: After almost twenty years of intense work on the celebrated LaAlO3/SrTiO3 system, the recent discovery of a superconducting two-dimensional electron gases (2-DEG) in (111)-oriented KTaO3-based heterostructures injects new momentum to the field of oxides interfaces. However, while both interfaces share common properties, experiments also suggest important differences between the two systems. Here, we report gate tunable superconductivity in 2-DEGs generated at the surface of a (111)-oriented KTaO3 crystal by the simple sputtering of a thin Al layer. We use microwave transport to show that (111)-KTaO3 2-DEGs exhibit a node-less superconducting order parameter with a gap value significantly larger than expected within a simple BCS weak-coupling limit model. Consistent with the two-dimensional nature of superconductivity, we evidence a well-defined Berezinsky-Kosterlitz-Thouless type of transition, which was not reported on SrTiO3-based interfaces. Our finding offers innovative perspectives for fundamental science but also for device applications in a variety of fields such as spin-orbitronics and topological electronics.
On Relative Central Extensions and Covering Pairs
Creators: name: Pourmirzaei, Azam
name: Hassanzadeh, Mitra
name: Mashayekhy, Behrooz
Publisher: name: arXiv
Year: 2016
Subjects: subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 20E34, 20E22, 20F05

description: Let $(G,N)$ be a pair of groups. In this article, first we construct a relative central extension for the pair $(G,N)$ such that special types of covering pair of $(G,N)$ are homomorphic image of it. Second, we show that every perfect pair admits at least one covering pair. Finally, among extending some properties of perfect groups to perfect pairs, we characterize covering pairs of a perfect pair $(G,N)$ under some extra assumptions.
description: 13 pages, to appear in Journal of Algebraic systems