Miracle-dz/UniFAR-FTUs huggingface dataset:
On the origin of two unidentified radio/X-ray sources discovered with XMM-Newton

We aim at clarifying the nature of the emission of two spatially related unidentified X-ray sources detected with XMM-Newton telescope at intermediate-low Galactic latitude. Observations reveal a point-like source aligned with elongated diffuse emission. The X-ray spectra are best-fitted by absorbed power laws with photon indices ~1.7 for the point-like and ~2.0 for the extended one. Both sources show nonthermal radio-continuum counterparts that might indicate a physical association. From the available data, we did not detect variability on the point-like source in several timescales. Two possible scenarios are analyzed: first, based on HI line absorption, assuming a Galactic origin, we infer a distance upper bound of 10^32 erg/s and >7.5 x 10^32 erg/s, for the point-like and extended sources, respectively; second, an extra-Galactic nature is discussed, where the point-like source might be the core of a radio galaxy and the extended source its lobe. In this case, we compare derived fluxes, spectral indices, and spatial correlation with those typical from the radio galaxy population, showing the feasibility of this alternative astrophysical scenario. From the available observational evidence, we suggest that the most promising scenario to explain the nature of these sources is a system consisting of a one-sided radio galaxy, where the point-like source is an active galactic nucleus and the extended source corresponds to the emission from its lobe. Other possibilities include a PSR/PWN origin, where the radio/X-ray emission originates from the synchrotron cooling of relativistic particles in the PSR magnetic field or a casual alignment between two unrelated sources, such as an AGN core and a Galactic X-ray blob.
Path-dependent initialization of a single quantum dot exciton spin in a nanophotonic waveguide

We demonstrate a scheme for in-plane initialization of a single exciton spin in an InGaAs quantum dot (QD) coupled to a GaAs nanobeam waveguide. The chiral coupling of the QD and the optical mode of the nanobeam enables spin initialization fidelity approaching unity in magnetic field B = 1 T and > 0.9 without the field. We further show that this in-plane excitation scheme is independent of the incident excitation laser polarization and depends solely on the excitation direction. This scheme provides a robust in-plane spin excitation basis for a photon-mediated spin network for quantum information applications.
Eye Movements during Reading and their Relationship to Reading Assessment Outcomes in Swedish Elementary School Children

The characteristics of children’s eye movements during reading change as they gradually become better readers. However, few eye tracking studies have investigated children’s reading and reading development and little is known about the relationship between reading- related eye movement measures and reading assessment outcomes. We recorded and analyzed three basic eye movement measures in an ecologically valid eye-tracking set-up. The participants were Swedish children (n = 2876) who were recorded in their normal school environment. The relationship between eye movements and reading assessment outcomes was analyzed in using linear mixed effects models. We found similar age-related changes in eye movement characteristics as established in previous studies, and that eye movements seem to correlate with reading outcome measures. Additionally, our results show that eye movements predict the results on several tests from a word reading assessment. Hence eye tracking may potentially be a useful tool in assessing reading development.
Corporate Effective Tax Rates for Research and Policy

How much companies pay in corporate income taxes is often better captured by effective tax rates (ETRs) rather than by statutory ones. Economists further distinguish between those modeled using the law—forward-looking ETRs—and those estimated from actual data on companies’ profits and taxes—backward-looking ETRs. In this article, I move beyond this distinction, and I break down backward-looking ETRs according to the type of data used to estimate them. I focus on backward-looking ETRs that are estimated using companies’ balance sheet databases. Based on my review of recent findings, I argue that backward-looking ETRs—of multinational corporations in particular—have become more frequently estimated thanks to advances in data availability while also becoming more relevant as a result of ongoing global corporate tax reform debates.
Recursive Path-Summing Simulation of Quantum Computation

Classical simulation of quantum computation has often been viewed as the method to determine where the horizon of quantum supremacy is located---that is, where quantum computation can no longer be simulated by classical methods. As of now, the 50 qubit threshold for quantum supremacy has been determined largely by the state vector simulation method's exponential space demands placing an upper bound on simulation memory capabilities. To investigate this claim, we present and test an implementation of a known path integral simulation algorithm running in linear space; the method is based on recursively traversing the underlying computation tree for quantum algorithms and summing over possible amplitudes. We find that the implementation is able to simulate the hidden subgroup method (HSP) standard method---a notable class of circuits including Shor's algorithm amongst others---in a reasonable amount of time using extremely low memory, as well as other circuits with similar parameters. The performance results of this algorithm suggest that it can serve as a feasible alternative to state vector simulation and that with respect to the HSP standard method, quantum supremacy may be more accurately measured using the recursive path-summing method on large numbers of qubits, compared to the state vector method.
MAPPING THE THREE-DIMENSIONAL “X-SHAPED STRUCTURE” IN MODELS OF THE GALACTIC BULGE

Numerical simulations have shown that the X-shaped structure in the Milky Way bulge can naturally arise from bar instability and buckling instability. To understand the influence of buckling amplitude on the morphology of the X-shape, we analyze three self-consistent numerical simulations of barred galaxies with different buckling amplitudes (strong, intermediate, and weak). We derive the three-dimensional density using an adaptive kernel smoothing technique. The face-on isodensity surfaces are all elliptical, while in the edge-on view, the morphology of buckled bars transitions with increasing radius from a central boxy core to a peanut bulge and then to an extended, thin bar. Based on these isodensity surfaces at different density levels, we find no clear evidence for a well-defined structure shaped like the letter X. The X-shaped structure is more peanut-like, the visual perception of which is probably enhanced by the pinched inner concave isodensity contours. The peanut bulge can reproduce qualitatively the observed bimodal distributions that were used as evidence for the discovery of the X-shape. The central boxy core is shaped like an oblong tablet, extending ∼500 pc above and below the Galactic plane ( ∣ b ∣ ∼ 4 ° ? > ). From the solar perspective, lines of sight passing through the central boxy core do not show bimodal distributions. This generally agrees with the observations that double peaks merge at ∣ b ∣ ? > ∼ 4°–5° from the Galactic plane, indicating the presence of a possibly similar structure in the Galactic bulge.
Advances in mean-field dynamo theories

Abstract We give a short introduction to the subject and review advances in understanding the basic ingredients of the mean-field dynamo theory. The discussion includes the recent analytic and numerical work in developments for the mean electromotive force of the turbulent flows and magnetic field, the nonlinear effects of the magnetic helicity, the non-local generation effects in the dynamo. We give an example of the mean-field solar dynamo model that incorporates the fairly complete expressions for the mean-electromotive force, the subsurface shear layer and the conservation of the total helicity. The model is used to shed light on the issues in the solar dynamo and on the future development of this field of research.
Preinflationary genesis with CMB B-mode polarization

Recent B-mode polarization observation seems to imply the tensor tilt n(T) greater than or similar to 1 at large angular scale if the primordial signal is dominated. We show that for a primordial universe, which is in a slowly expanding genesis phase before the slow-roll inflation, the primordial tensor spectrum will get a large-scale cutoff, i.e., n(T) greater than or similar to 1 at large scales while n(T) similar or equal to 0 at small scale. We find that this inflationary scenario not only may be consistent with the observation, but also predicts a large-scale anomaly in BB power spectrum, i.e., due to the large suppression of tensor perturbation amplitude we will hardly see the reionization bump at low-l, which may be falsified by the Planck polarization data.
Effects of random potentials in three-dimensional quantum electrodynamics

Three-dimensional quantum electrodynamics exhibits a number of interesting properties, such as dynamical chiral symmetry breaking, weak confinement, and non-Fermi liquid behavior, and also has wide applications in condensed matter physics. We study the effects of random potentials, which exist in almost all realistic condensed-matter systems, on the low-energy behaviors of massless Dirac fermions by means of renormalization group method, and show that the role of random mass is significantly enhanced by the gauge interaction, whereas random scalar and vector potentials are insusceptible to the gauge interaction at the one-loop order. The static random potential breaks the Lorentz invariance, and as such induces unusual renormalization of fermion velocity. We then consider the case in which three types of random potentials coexist in the system. The random scalar potential is found to play a dominant role in the low-energy region, and drives the system to undergo a quantum phase transition.
THE EVOLUTION OF HIGH-TEMPERATURE PLASMA IN MAGNETAR MAGNETOSPHERES AND ITS IMPLICATIONS FOR GIANT FLARES

In this paper we propose a new mechanism describing the initial spike of giant flares in the framework of the starquake model. We investigate the evolution of a plasma on a closed magnetic flux tube in the magnetosphere of a magnetar in the case of a sudden energy release, and discuss the relationship with observations of giant flares. We perform one-dimensional, numerical simulations of the relativistic magnetohydrodynamics in Schwarzschild geometry. We assume energy is injected at the footpoints of the loop by a hot star surface containing random perturbations of the transverse velocity. Alfvén waves are generated and propagate upward, accompanying very hot plasma which is also continuously heated by nonlinearly generated compressive waves. We find that the front edges of the fireball regions collide at the top of the tube with their symmetrically launched counterparts. This collision results in an energy release that can describe the light curve of the initial spikes of giant flares.
X-RAY EMISSION FROM ETA CARINAE NEAR PERIASTRON IN 2009. I. A TWO-STATE SOLUTION

X-ray emission from the supermassive binary system η Car declines sharply around periastron. This X-ray minimum has two distinct phases—the lowest flux phase in the first ∼3 weeks and a brighter phase thereafter. In 2009, the Chandra X-ray Observatory monitored the first phase five times and found the lowest observed flux at ∼1.9 × 10−12 erg cm−2 s−1 (3–8 keV). The spectral shape changed such that the hard band above ∼4 keV dropped quickly at the beginning and the soft band flux gradually decreased to its lowest observed value in ∼2 weeks. The hard band spectrum had begun to recover by that time. This spectral variation suggests that the shocked gas producing the hottest X-ray gas near the apex of the wind–wind collision (WWC) is blocked behind the dense inner wind of the primary star, which later occults slightly cooler gas downstream. Shocked gas previously produced by the system at earlier orbital phases is suggested to produce the faint residual X-ray emission seen when the emission near the apex is completely blocked by the primary wind. The brighter phase is probably caused by the re-appearance of the WWC plasma, whose emissivity significantly declined during the occultation. We interpret this to mean that the X-ray minimum is produced by a hybrid mechanism of an occultation and a decline in the emissivity of the WWC shock. We constrain timings of superior conjunction and periastron based on these results.
Calculation of intrinsic spin Hall conductivity by Wannier interpolation

\textit{Ab-initio} calculation of intrinsic spin Hall conductivity (SHC) generally requires a strict convergence criterion and a dense k-point mesh to sample the Brillouin zone, making its convergence challenging and time-consuming. Here we present a scheme for efficiently and accurately calculating SHC based on maximally localized Wannier function (MLWF). The quantities needed by the Kubo formula of SHC are derived in the space of MLWF and it is shown that only the Hamiltonian, the overlap and the spin operator matrices are required from the initial \textit{ab-initio} calculation. The computation of these matrices and the interpolation of Kubo formula on a dense k-point mesh can be easily achieved. We validate our results by prototypical calculations on fcc Pt and GaAs, which demonstrate that the Wannier interpolation approach is of high accuracy and efficiency. Calculations of $\alpha$-Ta and $\beta$-Ta show that SHC of $\beta$-Ta is 2.7 times of $\alpha$-Ta, while both have the opposite sign relative to fcc Pt and are an order of magnitude smaller than Pt. The calculated spin Hall angle of $-0.156$, is quite consistent with previous experiment on $\beta$-Ta, further suggesting intrinsic contribution may dominate in $\beta$-Ta. Our approach could facilitate large-scale SHC calculations, and may benefit the discovery of materials with high intrinsic SHC.
Ultraquantum magnetoresistance in single-crystalline $\beta $-Ag$_2$Se

In the history of condensed matter physics, reinvestigation of a well-studied material with enhanced quality sometimes led to important scientific discoveries. A well-known example is the discovery of fractional quantum Hall effect in high quality GaAs/AlGaAs heterojunctions. Here we report the first single crystal growth and magnetoresistance (MR) measurements of the silver chalcogenide β-Ag2Se (Naumannite), a compound has been known for the unusual, linear-fielddependent MR in its polycrystalline form for over a decade [1, 2]. With the quantum limit (QL) as low as 3 Tesla, a moderate field produced by a superconductor magnet available in many laboratories can easily drive the electrons in Ag2Se to an unprecedented state. We observed significant negative longitudinal MR beyond the QL, which was understood as a ‘charge-pumping’ effect between the novel fermions with opposite chiralities. Characterization of the single-crystalline Ag2Se and the fabrication of electric devices working above the QL, will represent a new direction for the study of these exotic electrons.
Data-driven subtraction of anisotropic flows in jet-like correlation studies in heavy-ion collisions

Background: Measurements of two-particle azimuthal angle correlation are an useful tool to study the distribution of jet energy loss, however, they are complicated because of the significant anisotropic flow background. Purpose: We devise a data-driven method for subtracting anisotropic flow background in jet-like correlation analysis. Method: We first require a large recoil momentum ($P_x$) with in a given pseudo-rapidity ($\eta$) range from a high-transverse momentum particle to enhance in-acceptance population of away-side jet-like correlations. Then we take the difference of two-particle correlation in the close-region and far-region with respect to the $\eta$ region of $P_x$ to subtract the anisotropic flow background. Results: We use a toy model which contains only anisotropic flow and PYTHIA8 which have jets to demonstrate the validity of our data-driven method. Conclusions: The results indicate that the data-driven method can subtract anisotropic flow effectively.
Applications of distance between probability distributions to gravitational wave data analysis

We present a definition of the distance between probability distributions. Our definition is based on the L1 norm on space of probability measures. We compare our distance with the well-known Kullback–Leibler divergence and with the proper distance defined using the Fisher matrix as a metric on the parameter space. We consider using our notion of distance in several problems in gravitational wave data analysis: to place templates in the parameter space in searches for gravitational-wave signals, to assess quality of search templates, and to study the signal resolution.
A Sociological Lens on Linguistic Diversity: Implications for Writing Inclusive Multiple-Choice Assessments

Multiple-choice questions (MCQs) are widely used in large introductory courses. Recent research focuses on MCQ reliability and validity and overlooks questions of accessibility. Yet, access to the norms of academic discourse embedded in MCQs differs between groups of first-year students. We theorize these norms as part of the institutionalized cultural symbols that reproduce social and cultural exclusion for linguistically diverse students. A sociological focus on linguistic diversity is necessary as the percentage of students who use English as an additional language (EAL), rather than English as a native language (ENL), has grown. Drawing on sociology as pedagogy, we problematize MCQs as a medium shaping linguistically diverse students’ ability to demonstrate disciplinary knowledge. Our multimethod research uses two-stage randomized exams and focus groups with EAL and ENL students to assess the effects of a modification in instructors’ MCQ writing practices in sociology and psychology courses. Findings show that students are more likely to answer a modified MCQ correctly, with greater improvement for EAL students.
Mass of Neutron Star in SdS space-time

Abstract In this work we present a modiﬁed TOV equation which incorpo-rates the cosmological constant with regard to the recent astronomical obser-vations that the Universe is in a phase of accelerated expansion. Using thismodiﬁed TOV equation we considered the structure of a neutron star in SdSspace-time and calculated maximum mass limit for neutron stars.Keywords TOV equation · Neutron Star · Maximum mass · cosmologicalconstantPACS 97.60. Jd · 26.60. Kp · 04.40. Dg1 IntroductionNeutron stars can be included in the class of compact stars which are starswith high mass and small radius and their density will be very high. So weneed to take into account eﬀects from general relativity, like the curvature ofspace–time in the study of neutron stars. Baade and Zwicky were the ﬁrst topropose the idea of neutron stars (Baade and Zwicky, 1934), pointing out thatthey have very high density and small radius. They also made a very impor-tant suggestion that neutron stars would be formed in supernova explosions.We know that there are two forces acting on a star, one of them is gravitationand the second one arises from the pressure. The opposing force of gravita-tion will be thermal pressure for ordinary stars and degeneracy pressure forwhite dwarfs and neutron stars. Thus we can obtain two coupled diﬀerentialequations for mass and pressure which tell their change with the radius of the
Hard-Core Radius of Nucleons within the Induced Surface Tension Approach

We review the recent approach to model the hadronic and nuclear matter equations of state using the induced surface tension concept, which allows one to go far beyond the usual Van der Waals approximation. Since the obtained equations of state, classical and quantum, are among the most successful ones in describing the properties of low density phases of strongly interacting matter, they set strong restrictions on the possible value of the hard-core radius of nucleons, which is widely used in phenomenological equations of state. We summarize the latest results obtained within this novel approach and perform a new detailed analysis of the hard-core radius of nucleons, which follows from hadronic and nuclear matter properties. Such an analysis allows us to find the most trustworthy range of its values: the hard-core radius of nucleons is 0.3–0.36 fm. A comparison with the phenomenology of neutron stars implies that the hard-core radius of nucleons has to be temperature and density dependent. Such a finding is supported when the eigenvolume of composite particles like hadrons originates from their fermionic substructure due to the Pauli blocking effect.
Evaluating $V_{ud}$ from neutron beta decays

Although well studied, the neutron still offers a unique laboratory for precise tests of Standard Model (SM) predictions. Neutron decay is free of nuclear structure corrections present in nuclear beta decays, and, with a $10^8$ times larger branching ratio than the theoretically cleaner pion beta decay, it is more readily accessible to experimental study than the latter. Measurements at sufficient precision of the neutron lifetime, and of correlations in free neutron beta decay, offer several stringent tests of the SM, including the weak quark couplings (quark-lepton universality), and certain extensions beyond the standard $V-A$ weak interaction theory. This paper focuses on the long-running free neutron beta decay experimental program aimed at obtaining an independent determination of the Cabibbo-Kobayashi-Maskawa (CKM) mixing matrix element $V_{ud}$. We discuss the present state of precision achieved in this program and briefly review the currently active projects, as well as the expected near-term improvements in the field.