Miracle-dz/UniFAR-FTUs huggingface dataset:
A vector type of Unruh-DeWitt–like detector

We study a type of an Unruh-DeWitt–like detector based on a vector rather than a scalar field. This detector has two energy states and produces Larmor radiation when there is no energy gap between them. This setup indicates that Larmor radiation and Unruh radiation are two counterparts of the same phenomenon. Larmor radiation is observed in the inertial frame, while Unruh radiation is observed in an accelerated frame. The accelerated observer sees that his detector absorbed a particle inside its own accelerated horizon, while the Larmor radiation is the companion particle which leaves the accelerated observer's horizon. Since the detection is based on the electromagnetic field, this type of detector is much closer to the real world than a standard Unruh-DeWitt detector which is coupled to a scalar field.
Evidence for Different Disk Mass Distributions between Early- and Late-type Be Stars in the BeSOS Survey

The circumstellar disk density distributions for a sample of 63 Be southern stars from the BeSOS survey were found by modeling their Hα emission line profiles. These disk densities were used to compute disk masses and disk angular momenta for the sample. Average values for the disk mass are 3.4 × 10−9 and 9.5 × 10−10 M⋆ for early (B0–B3) and late (B4–B9) spectral types, respectively. We also find that the range of disk angular momentum relative to the star is (150–200)J⋆/M⋆ and (100–150)J⋆/M⋆, again for early- and late-type Be stars, respectively. The distributions of the disk mass and disk angular momentum are different between early- and late-type Be stars at a 1% level of significance. Finally, we construct the disk mass distribution for the BeSOS sample as a function of spectral type and compare it to the predictions of stellar evolutionary models with rapid rotation. The observed disk masses are typically larger than the theoretical predictions, although the observed spread in disk masses is typically large.
High field carrier transport in graphene: Insights from fast current transient

In this work, we observe gate tunable negative differential conductance (NDC) and current saturation in single layer and bilayer graphene transistor at high source-drain field, which arise due to the interplay among (1) self-heating, (2) hot carrier injection, and (3) drain induced minority carrier injection. The magnitude of the NDC is found to be reduced for a bilayer, in agreement with its weaker carrier-optical phonon coupling and less efficient hot carrier injection. The contributions of different mechanisms to the observed results are decoupled through fast transient measurements with nanosecond resolution. The findings provide insights into high field transport in graphene. (C) 2012 American Institute of Physics. http://dx.doi. org/10.1063/1.4754103]
Discovery of a Luminous Quasar in the Nearby Universe

In the course of the Pico dos Dias survey (PDS), we identified the stellar-like object PDS 456 at coordinates α = 17h28m19. ˢ796, δ = -14°15'55. ″87 (epoch 2000), with a relatively nearby (z = 0.184) and bright (B = 14.69) quasar. Its position at Galactic coordinates l = 10. °4, b = +11. °2, near the bulge of the Galaxy, may explain why it was not detected before. The optical spectrum of PDS 456 is typical of a luminous quasar, showing a broad (FWHM ~ 4000 km s-1) Hβ line, very intense Fe II lines, and a weak [O III] λ5007 line. PDS 456 is associated to the infrared source IRAS 17254-1413 with a 60 μm infrared luminosity L60 = 3.8 × 1045 ergs s-1. The relatively flat slopes in the infrared [α(25, 60) = -0.33 and α(12, 25) = -0.78] and a flat power index in the optical (Fν ∝ ν-0.72) may indicate a low dust content. A good match between the position of PDS 456 and the position of the X-ray source RXS J172819.3-141600 implies an X-ray luminosity LX = 2.8 × 1044 ergs s-1. The good correlation between the strength of the emission lines in the optical and the X-ray luminosity, as well as the steep optical to X-ray index estimated (αOX = -1.64), suggests that PDS 456 is radio quiet. A radio survey previously performed in this region yields an upper limit for radio power at about 5 GHz of approximately 2.6 × 1030 ergs-1 Hz-1. We estimate the Galactic reddening in this line of sight to be AB ≃ 2.0, implying an absolute magnitude MB = -26.7 (using H0 = 75 km s-1 Mpc-1 and q0 = 0). In the optical, PDS 456 is therefore 1.3 times more luminous than 3C 273 and the most luminous quasar in the nearby (z ≤ 0.3) universe.
Nonlinear electrodynamics, singularities and accelerated expansion

Non-linear electrodynamics coupled to general relativity is investigated. In general relativity, it is observed that the expansion of the universe is accelerating if the source of the gravitational field is the non-linear electromagnetic field. Moreover, a pure magnetic universe is explored. As a result, it is demonstrated that the magnetic field drives the cosmic expansion to be accelerated. Furthermore, the stability analysis of the present model is developed. In addition, the energy conditions and future singularities are studied in detail.
Quantum description of light-pulse scattering on a single atom in waveguides

We present a time-dependent quantum calculation of the scattering of a few-photon pulse on a single atom. The photon wave packet is assumed to propagate in a transversely strongly confined geometry, which ensures strong atom-light coupling and allows a quasi-one-dimensional treatment. The amplitude and phase of the transmitted, reflected, and transversely scattered part of the wave packet strongly depend on the pulse length (bandwidth) and energy. For a transverse mode size of the order of ${\ensuremath{\lambda}}^{2},$ we find nonlinear behavior for a few photons already, or even for a single photon. In a second step we study the collision of two such wave packets at the atomic site and find striking differences between the Fock state and coherent state wave packets of the same photon number.
Portevin-Le Chatelier Effect: a Poisson Process

The Portevin-Le Chatelier (PLC) effect is a kind of plastic instability observed in many dilute alloys when deformed at certain ranges of strain rate and temperature. In this letter we establish that the dynamical process responsible for the PLC effect is Poisson in nature by applying statistical analysis to the observed experimental data obtained during the PLC effect in a substitutional alloy, Al-2.5%Mg and in an interstitial alloy, low carbon steel subjected to uniaxial tensile test at constant imposed strain rate.
Heavy quark form factors at two loops

We compute the two-loop QCD corrections to the heavy quark form factors in case of the vector, axial-vector, scalar and pseudo-scalar currents up to second order in the dimensional parameter $\epsilon = (4-D)/2$. These terms are required in the renormalization of the higher order corrections to these form factors.
Reply to “Comment on ‘High-pressure phases of group-II difluorides: Polymorphism and superionicity’ ”

Cazorla et al. [preceding comment] criticize our recent results on the high-PT phase diagram of CaF2 (Phys. Rev. B 95, 054118 (2017)). According to our analysis, Cazorla et al. have not converged their calculations with respect to simulation cell size, undermining the comment's conclusions about both the high-T behaviour of the P-62m-CaF2 polymorph, and the use of the QHA in our work. As such, we take this opportunity to emphasise the importance of correctly converging molecular dynamics simulations to avoid finite-size errors. We compare our quasiharmonic phase diagram for CaF2 with currently available experimental data, and find it to be entirely consistent and in qualitative agreement with such data. Our prediction of a superionic phase transition in P-62m-CaF2 (made on the basis of the QHA) is shown to be accurate, and we argue that simple descriptors, such as phonon frequencies, can offer valuable insight and predictive power concerning superionic behaviour.
Magnetic domain structure and dynamics in interacting ferromagnetic stacks with perpendicular anisotropy

The time and field dependence of the magnetic domain structure at magnetization reversal were investigated by Kerr microscopy in a structure consisting of a hard and a soft ferromagnetic Co∕Pt multilayer stack with perpendicular anisotropy, separated by a thicker nonmagnetic Pt spacer layer. Large local inhomogeneous magnetostatic stray fields appear as soon as a nonuniform magnetic area exists within one of the stacks and induce a correlated domain structure within the other. The long range nature of this magnetostatic interaction gives rise to ultraslow dynamics even in zero applied field, i.e., it affects the long time domain stability. Due to this additional interaction field, the magnetization reversal under short magnetic field pulses differs markedly from the well-known slow dynamic behavior. Namely, in high field, the magnetization of the coupled harder layer has been observed to reverse more rapidly by domain wall motion than the softer layer alone.
Bihelical magnetic relaxation and large scale magnetic field growth

A unified, three-scale system of equations accommodating nonlinear velocity driven helical dynamos, as well as time-dependent relaxation of magnetically dominated unihelical or bihelical systems is derived and solved herein. When opposite magnetic helicities of equal magnitude are injected on the intermediate and small scales, the large scale magnetic helicity grows kinematically (independent of the magnetic Reynolds number) to equal that on the intermediate scale. For both free and driven relaxation large scale fields are rapidly produced. Subsequently, a dissipation-limited dynamo, driven by growth of small scale kinetic helicity, further amplifies the large scale field. The results are important for astrophysical coronae fed with bihelical structures by dynamos in their host rotators. The large scale for the rotator corresponds to the intermediate scale for the corona. That bihelical magnetic relaxation can produce global scale fields may help to explain the formation of astrophysical coronal holes and magnetohydrodynamic outflows.
Evolution of the probability distribution function of galaxies in redshift space

We present a new analytic calculation for the redshift-space evolution of the one-point galaxy probability distribution function (PDF). The non-linear evolution of the matter density field is treated by second-order Eulerian perturbation theory and transformed to the galaxy density field via a second-order local biasing scheme. We then transform the galaxy density field to redshift space, again to second order. Our method uses an exact statistical treatment based on the Chapman–Kolmogorov equation to propagate the probability distribution of the initial mass field to the final redshifted galaxy density field. The moment generating function of the PDF is derived and used to find a new, closed-form expression for the skewness of the redshifted galaxy distribution. The formalism is shown to be general enough to allow a non-deterministic (or stochastic) biasing prescription. We demonstrate the dependence of the redshift-space PDF on cosmological and biasing parameters. Our results are compared with existing models for the PDF in redshift space and with the results of biased N-body simulations. We find that our PDF accurately models the redshift-space evolution and the non-linear biasing.
Raising Rivals’ Costs: Vertical Market Power in Natural Gas Pipelines and Wholesale Electricity Markets

In recent years, New England has experienced severe, contemporaneous price spikes in its natural gas and wholesale electricity markets. Although these spikes are commonly attributed to limited pipeline capacity serving the region, we demonstrate that they have been exacerbated by firms with long-term contracts for pipeline capacity scheduling for deliveries without actually flowing gas. We analyze firms’ scheduling patterns on the Algonquin pipeline and identify the institutional conditions that enable and incentivize this capacity-withholding behavior. We find that some firms are able to offset the opportunity cost of unused capacity by increasing the price of the gas they do sell in the spot market and by increasing the interconnected wholesale electricity price, which increases the revenues of infra-marginal generation resources owned by their parent energy companies. Finally, we employ an economic dispatch model to estimate the welfare losses, emissions consequences, and distributional impacts of capacity withholding over the period from 2014-2016.
X-ray transparent gasket for diamond anvil cell high pressure experiments

The diamond anvil cell is a fundamental tool for investigating properties under extreme conditions. However, our knowledge of material behavior under high pressure has been limited by a lack of measurement capability in radial directions. In this study we introduce a gasketing technique based on a combination of Kapton, amorphous boron, and epoxy, that reliably solves this issue. We demonstrate how these gaskets allow precise imaging of stress, strain, and microscopic properties such as texture and lattice preferred orientations within the sample, in situ, up to pressures in the range of 65GPa.
The Influence of External Real and White Noise on the LOTKA‐VOLTERRA Model

The behaviour of a marginally stable predator‐prey system, the LOTKA‐VOLTERRA model is analyzed under the influence of parameter fluctuations. The cases of white and real noise are studied separately. It is shown that for white noise no stationary solution exists, but even for time tending to infinity explosion occurs only with zero probability. In the case of real noise the class of noise processes that permit a stationary solution is characterized by their spectral density. It turns out that this class consists of all stationary processes that do not contain the eigenfrequencies of the LOTKA‐VOLTERRA system. It is shown that for all other real noise processes a resonance phenomenon occurs and the solutions grow unboundedly. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA
Maximally Permissive Petri Net Supervisors for Flexible Manufacturing Systems with Uncontrollable and Unobservable Transitions

This paper presents a deadlock prevention policy to obtain behaviorally optimal supervisors for flexible manufacturing systems with uncontrollable and unobservable transitions. The conditions of uncontrollability and unobservability of transitions are revealed in the sense of the implementation of a Petri net supervisor. Then, integer linear programming models are designed to obtain a Petri net supervisor such that all legal markings are reachable and the number of control places is reduced. We also show that a controllable transition can be unobservable and self‐loops can be used to disable the transition but do not observe its firing. Finally, examples are provided to illustrate the proposed approach.
Insulating gap in FeO: Correlations and covalency

We report calculations of the electronic structure of FeO in the local-density approximation (LDA) and LDA+U approximation with and without rhombohedral distortion. In both cases LDA renders an antiferromagnetic metal, and LDA+U opens a Hubbard gap. However, the character of the gap is qualitatively different in the two structures, and the difference can be traced down to the underlying LDA band structure. An analysis of the calculations gives insight into the origin of the insulating gap in 3d monoxides, and into the role of the k dependency of U, missing in the contemporary LDA+U method.
Angular Range and Uncertainty Analysis of Nonorthogonal Crossed Hot Wire Probes

Crossed hot wire probes are widely used for measuring two-dimensional flows. Many applications in fluid mechanics like turbomachinery require an angular range as large as possible and a reasonable uncertainty in both direction and velocity values. The classic design places the wires orthogonally, while an angle between the probe wires allows a wider angular range to be obtained. We show an experimental and a theoretical study of the response of this kind of probes, by analyzing the dependence of the calibration procedure and uncertainties of flow angle and velocity with the angle between the wires
Electrical switching of perpendicular magnetization in a single ferromagnetic layer

Electrical manipulation of magnetization is essential for integration of magnetic functionalities such as magnetic memories and magnetic logic devices into electronic circuits. The current induced spin-orbit torque (SOT) in heavy metal/ferromagnet (HM/FM) bilayers via the spin Hall effect in the HM and/or the Rashba effect at the interfaces provides an efficient way to switch the magnetization. In the meantime, current induced SOT has also been used to switch the in-plane magnetization in single layers such as ferromagnetic semiconductor (Ga,Mn)As and antiferromagnetic metal CuMnAs with globally or locally broken inversion symmetry. Here we demonstrate the current induced perpendicular magnetization switching in L10 FePt single layer. The current induced spin-orbit effective fields in L10 FePt increase with the chemical ordering parameter (S). In 20 nm FePt films with high S, we observe a large charge-to-spin conversion efficiency and a switching current density as low as 7.0E6 A/cm2. We anticipate our findings may stimulate the exploration of the spin-orbit torques in bulk perpendicular magnetic anisotropic materials and the application of high-efficient perpendicular magnetization switching in single FM layer.
A solar system test of self-interacting dark matter

Dark matter (DM) self-interactions affect the gravitational capture of DM in the Sun and Earth differently as a simple consequence of the differing kinematics of collisions within the two potential wells: the dominant effect of self-interactions in the Sun is to provide an additional channel for capture, while the dominant effect in the Earth is to eject previously captured DM. We point out that this simple observation can be used to deduce the existence of DM self-interactions by comparing the annihilation rates of DM gravitationally bound within the Sun and Earth. We compute the Sun and Earth annihilation fluxes for DM with spin-independent nuclear cross-sections and thermal annihilation cross-sections and demonstrate that, for cross-sections allowed by direct detection, self-interactions can easily suppress the expected Earth flux by multiple orders of magnitude. This suppression is potentially significant even for self-interaction cross-sections orders of magnitude below the Bullet Cluster bounds, making this solar system comparison a leading test of dark matter self-interactions. Additionally, we consider thermalization of the captured DM population with the nuclei of the capturing body in some detail, accounting for both nuclear and self-interactions, and point out some consequential and broadly applicable considerations.
Correction of Near-infrared High-resolution Spectra for Telluric Absorption at 0.90–1.35 μm

We report a method of correcting a near-infrared (0.90–1.35 μm) high-resolution (λ/Δλ ∼ 28,000) spectrum for telluric absorption using the corresponding spectrum of a telluric standard star. The proposed method uses an A0 V star or its analog as a standard star from which on the order of 100 intrinsic stellar lines are carefully removed with the help of a reference synthetic telluric spectrum. We find that this method can also be applied to feature-rich objects having spectra with heavily blended intrinsic stellar and telluric lines and present an application to a G-type giant using this approach. We also develop a new diagnostic method for evaluating the accuracy of telluric correction and use it to demonstrate that our method achieves an accuracy better than 2% for spectral parts for which the atmospheric transmittance is as low as ∼20% if telluric standard stars are observed under the following conditions: (1) the difference in airmass between the target and the standard is ≲ 0.05 ; and (2) that in time is less than 1 hr. In particular, the time variability of water vapor has a large impact on the accuracy of telluric correction and minimizing the difference in time from that of the telluric standard star is important especially in near-infrared high-resolution spectroscopic observation.
Visible spectra of (474640) 2004 VN112–2013 RF98 with OSIRIS at the 10.4 m GTC: evidence for binary dissociation near aphelion among the extreme trans-Neptunian objects

The existence of significant anisotropies in the distributions of the directions of perihelia and orbital poles of the known extreme trans-Neptunian objects (ETNOs) has been used to claim that trans-Plutonian planets may exist. Among the known ETNOs, the pair (474640) 2004 VN112-2013 RF98 stands out. Their orbital poles and the directions of their perihelia and their velocities at perihelion/aphelion are separated by a few degrees, but orbital similarity does not necessarily imply common physical origin. In an attempt to unravel their physical nature, visible spectroscopy of both targets was obtained using the OSIRIS camera-spectrograph at the 10.4 m Gran Telescopio Canarias (GTC). From the spectral analysis, we find that 474640-2013 RF98 have similar spectral slopes (12 vs. 15 %/0.1um), very different from Sedna's but compatible with those of (148209) 2000 CR105 and 2012 VP113. These five ETNOs belong to the group of seven linked to the Planet Nine hypothesis. A dynamical pathway consistent with these findings is dissociation of a binary asteroid during a close encounter with a planet and we confirm its plausibility using N-body simulations. We thus conclude that both the dynamical and spectroscopic properties of 474640-2013 RF98 favour a genetic link and their current orbits suggest that the pair was kicked by a perturber near aphelion.
Optical simulation of a quantum thermal machine

In this paper we introduce both a theoretical and an experimental scheme of an all-optical quantum thermal engine, where the working substance and the thermal reservoirs can be efficiently encoded in internal degrees of freedom of a single-photon. By using polarization and propagation path, we encode two quantum bits and then implement the thermodynamical steps of an Otto cycle. To illustrate the feasibility of our proposal, we experimentally realize such optical thermal engine through an intense laser beam, evaluating heat and work at each individual step of the thermodynamical cycle. In addition, from the analysis of the entropy production during the entire cycle, we can study the amount of quantum friction produced in the Otto cycle as a function of the difference of temperature between hot and cold reservoirs. Our investigation constitutes, therefore, an \textit{all-optical-based thermal machine} and opens perspectives for other optical simulations in quantum thermodynamics.
The Inferred Redshift Distribution of the Faint Blue Galaxy Excess

We infer the redshift distribution of the faint blue galaxy excess (FBE) at mB = 23.5 by subtracting the predicted distribution of giant/normal galaxies from the observed N(z) distribution for all types. This is possible because of the recent deep Hubble Space Telescope (HST) WFPC2 morphological number counts that have convincingly demonstrated that little evolution of the giant population is seen to mB = 26.0. The mean redshift of the FBE at mB = 23.5 is found to be ⟨z⟩FBE = 0.40 ± 0.07 with upper and lower quartiles defined by z0.75 = 0.58 ± 0.05 and z0.25 = 0.28 ± 0.05, respectively. We compare this inferred FBE N(z) distribution to the predictions from three generic faint galaxy models: dwarf dominated (no-evolution), pure luminosity evolution, and evolving dwarfs. The inferred FBE N(z) distribution strongly supports a hybrid evolving dwarf-rich model wherein a large population of dwarfs present at z = 0.5 has subsequently faded to obscurity. The total integrated number density of dwarfs (down to MB = -11) is estimated to be a factor of 20 times greater than that of E-Sc galaxies and the estimated fading to be 1.0 < Δm < 1.4 mag. Thus, the dwarf population is estimated to be responsible for ~30% of the luminosity density locally, rising to ~57% at z = 0.5.