Miracle-dz/UniFAR-FTUs huggingface dataset:
An investigation of magnetic field distortions in accretion discs around neutron stars - I. Analysis of the poloidal field component

We report results from calculations investigating stationary magnetic field configurations in accretion discs around magnetised neutron stars. Our strategy is to start with a very simple model and then progressively improve it, providing complementary insight into results obtained with large numerical simulations. In our first model, presented here, we work in the kinematic approximation and consider the stellar magneticfield as being a dipole aligned withthe stellar rotation axis and perpendicular to the disc plane, while theflow in the disc is taken to be steady and axisymmetric. The behaviour in the radial direction is then independent of that in the azimuthal direction. We investigate the distortion of the field caused by interaction with the disc matter, solving the induction equation numerically in full 2D. The influence of turbulent diffusivity and fluid velocity on the poloidal field configuration is analysed, including discussion of outflows from the top and bottom of the disc. We find that the distortions increase with increasing magnetic Reynolds number Rm (calculated using the radial velocity). However, a single global parameter does not give an adequate description in different parts of the disc and we use instead a “magnetic distortion function” Dm(r ,θ ) (a magnetic Reynolds number defined locally). Where Dm � 1 (near to the inner edge of the disc) there is little distortion, but where Dm > 1 (most of the rest of the disc), there is considerable distortion and the field becomes weaker than the dipole would have been. Between these two regions, there is a transition zone where the field is amplified and can have a local minimum and maximum. The location of this zone depends sensitively on the diffusivity. The results depend very little on the boundary conditions at the top of the disc.
CP violation and CPT invariance in $B^\pm$ decays with final state interactions

We show that, besides the usual short distance contribution for CP violation, final state interactions together with CPT invariance can play an important role in the recent observation of CP violation in three-body charmless $B^\pm$ decays. A significant part of the observed CP asymmetry distribution in the Dalitz plot is located in a region where hadronic channels are strongly coupled. We illustrate our discussion comparing the recent observation of CP violation in the $B^\pm\to K^\pm K^+ K^-$ and $B^\pm\to K^\pm \pi^+ \pi^-$ phase space, with a calculation based on $\pi\pi\to KK$ scattering.
CONNECTIONS BETWEEN LOCAL AND GLOBAL TURBULENCE IN ACCRETION DISKS

We analyze a suite of global magnetohydrodynamic (MHD) accretion disk simulations in order to determine whether scaling laws for turbulence driven by the magnetorotational instability, discovered via local shearing-box studies, are globally robust. The simulations model geometrically thin disks with zero net magnetic flux and no explicit resistivity or viscosity. We show that the local Maxwell stress is correlated with the self-generated local vertical magnetic field in a manner that is similar to that found in local simulations. Moreover, local patches of vertical field are strong enough to stimulate and control the strength of angular momentum transport across much of the disk. We demonstrate the importance of magnetic linkages (through the low-density corona) between different regions of the disk in determining the local field, and suggest a new convergence requirement for global simulations—the vertical extent of the corona must be fully captured and resolved. Finally, we examine the temporal convergence of the average stress and show that an initial long-term secular drift in the local flux–stress relation dies away on a timescale that is consistent with turbulent mixing of the initial magnetic field.
A new, clean catalogue of extragalactic non-nuclear X-ray sources in nearby galaxies

We use the XMM-Newton Serendipitous Source Catalogue to create a catalogue of non-nuclear extragalactic X-ray sources that is both large, containing 1,464 sources, and clean, with steps taken to minimise contamination. This catalogue contains 372 ultraluminous X-ray sources (ULXs), objects with extreme luminosities ($L_{\rm X}>10^{39}$\,erg\,s$^{-1}$) higher than expected for a stellar-mass black hole (BH) accreting at its Eddington limit, and thought to mainly be super-Eddington accreting compact objects. We find the colour properties of ULXs to be similar to lower-luminosity sources, distinct from active galactic nuclei, and similar between populations in spiral and elliptical galaxies. Our catalogue contains eight new candidate intermediate-mass BHs (IMBHs) amongst the most luminous sources, 33 transient ULXs, and five ULXs with high short-term variability. Of these highly variable ULXs, we closely examine M51 ULX-7, which exhibits a persistently hard spectrum and evidence of band-limited noise, arguments in favour of it being an IMBH. However, a possible high-energy spectral turnover and its high dynamic range of flux bear similarities to properties observed in neutron star ULXs discovered to date. A useful subpopulation of our catalogue are sources at the Eddington Threshold ($10^{38}<L_{\rm X}<3\times10^{39}$\,erg\,s$^{-1}$), the luminosity regime in which stellar-mass BHs may be accreting at or just below the Eddington limit. Our catalogue contains 666 such objects, four of which we studied in detail and found to demonstrate the heterogeneous nature of this luminosity regime, including high-luminosity sub-Eddington accretion states, the ultraluminous supersoft accretion regime, and sources in intermediate accretion modes. Finally, we searched for evidence of the most highly obscured and down-scattered super-Eddington accreting sources by looking for ultraluminous ultraviolet (ULUV) sources in UV source catalogues. We discovered six ULUV candidates in the Swift UVOT catalogue that are ideal for follow-up observations using HST.
The rotation measures of high-luminosity sources as seen from the NVSS

We reanalyse the subset of the Faraday rotation measures data from the NRAO VLA Sky Survey catalogue for which redshift and spectral index information is available, in order to better elucidate the relations between these observables. We split this subset in two based on their radio luminosity, and find that higher power sources have a systematically higher residual rotation measure, once the regular field of the MilkyWay is subtracted. This rotation measure stands well above the variances due to the turbulent field of our Galaxy and measurement errors, contrarily to low-power sources. The effect is more pronounced as the energy threshold becomes more restrictive. If the two sets are merged, one observes an apparent evolution of rotation measure with redshift, but our analysis shows that this can be interpreted as an artefact of the different intrinsic properties of brighter sources that are typically observed at larger distances.
Holographic systems far from equilibrium: a review

In this paper we give an overview of some recent progress in using holography to study various far-from-equilibrium condensed matter systems. Non-equilibrium problems are notoriously difficult to deal with, not to mention at strong coupling and when including quantum effects. Remarkably, using holographic duality one can describe and follow the real-time evolution of far-from-equilibrium systems, including those which are spatially inhomogeneous and anisotropic, by solving partial differential gravity equations. We sample developments in two broad classes of question which have recently been of much interest to the condensed matter community: non-equilibrium steady states, and quantum systems undergoing a global quench. Our discussion focuses on the main physical insights obtained from the gravity approaches, rather than comprehensive treatment of each topic or detailed descriptions of gravity calculations. The paper also includes an overview of current numerical techniques, as well as the holographic Schwinger–Keldysh approach to real-time correlation functions.
The energy budget of stellar magnetic fields

Spectropolarimetric observations have been used to map stellar magnetic fields, many of which display strong bands of azimuthal fields that are toroidal. A number of explanations have been proposed to explain how such fields might be generated though none are definitive. In this paper, we examine the toroidal fields of a sample of 55 stars with magnetic maps, with masses in the range 0.1-1.5M(circle dot). We find that the energy contained in toroidal fields has a power-law dependence on the energy contained in poloidal fields. However the power index is not constant across our sample, with stars less and more massive than 0.5M(circle dot) having power indices of 0.72 +/- 0.08 and 1.25 +/- 0.06, respectively. There is some evidence that these two power laws correspond to stars in the saturated and unsaturated regimes of the rotation-activity relation. Additionally, our sample shows that strong toroidal fields must be generated axisymmetrically. The latitudes at which these bands appear depend on the stellar rotation period with fast rotators displaying higher latitude bands than slow rotators. The results in this paper present new constraints for future dynamo studies.
Examining the psychology of practitioners, institutions and structures:

‘Medically unexplained symptoms’ (MUS), through the lens of the biopsychosocial model, are understood in mainstream psy disciplines and related literature as a primarily psychosocial phenomenon perpetuated by ‘dysfunctional’ psychology on the part of people labelled with such. Biopsychosocial discourse and practice in this field, underpinned by little empirical foundation and lacking theoretical coherency, are associated with harms sustained by people labelled with MUS. Yet, little attention is paid to the psychology of social actors and institutions whose practice and policy derives from biopsychosocial theorising, or whose vested interests (re)produce such theorising. This article contends that lack of reflexivity among psy practitioners and other social actors on individual, institutional and structural levels furthers biopsychosocial hegemony and contributes to harms. Non-reflexive behaviour on the part of practitioners within clinical and ‘therapeutic’ encounters and on the part of social actors within institutions and broader power structures is examined, and possible psychological underpinnings of non-reflexivity are explored. Notably, the concept of gain, drawn from dominant discourse around MUS, is applied broadly to explore what might be gained from eschewing reflexivity and from adhering to biopsychosocial narratives. Implications for practice, supervision, training and research are discussed, notably highlighting a need for critical reflexivity in all domains.
Flooded Extent and Depth Analysis Using Optical and SAR Remote Sensing with Machine Learning Algorithms

Recurrent flooding occurs in most years along different parts of the Gulf of Mexico coastline and the central and southeastern parts of Mexico. These events cause significant economic losses in the agricultural, livestock, and infrastructure sectors, and frequently involve loss of human life. Climate change has contributed to flooding events and their more frequent occurrence, even in areas where such events were previously rare. Satellite images have become valuable information sources to identify, precisely locate, and monitor flooding events. The machine learning models use remote sensing images pixels as input feature. In this paper, we report a study involving 16 combinations of Sentinel-1 SAR images, Sentinel-2 optical images, and digital elevation model (DEM) data, which were analyzed to evaluate the performance of two widely used machine learning algorithms, gradient boosting (GB) and random forest (RF), for providing information about flooding events. With machine learning models GB and RF, the input dataset (Sentinel-1, Sentinel-2, and DEM) was used to establish rules and classify the set in the categories specified by previous tags. Monitoring of flooding was performed by tracking the evolution of water bodies during the dry season (before the event) through to the occurrence of floods during the rainy season (during the event). For detection of bodies of water in the dry season, the metrics indicate that the best algorithm is GB with combination 15 (F1m = 0.997, AUC = 0.999, K = 0.994). In the rainy season, the GB algorithm had better metrics with combination 16 (F1m = 0.995, AUC = 0.999, Kappa = 0.994), and detected an extent of flooded areas of 1113.36 ha with depths of <1 m. The high classification performance shown by machine learning algorithms, particularly the so-called assembly algorithms, means that they should be considered capable of improving satellite image classification for detection of flooding over traditional methods, in turn leading to better monitoring of flooding at local, regional, and continental scales.
The nature of the compact HII region Sh 2-89 and its stellar content

We present an analysis of the structure and properties of the compact HII region Sh 2-89, and certain of the young stellar objects (YSOs) within this regime, using mid-infrared (MIR) mapping derived from the Spitzer Space Telescope (SST) and visual slit spectroscopy of the inner regions of the source. We show that the region has a bipolar structure, and contains a variety of Class I and II YSOs. Much of the MIR emission appears to be dominated by PAH emission bands, which cause strong increases in flux in the 5.8 and 8.0 microns photometric channels, whilst the variation of H_alpha, [NII] at 6583 A, [SII] at 6716+6731 A, and MIR emission profiles confirms the presence of complex ionisation fronts, and ionisation stratification.
Magnetization reversal of giant perpendicular magnetic anisotropy at the magnetic-phase transition in FeRh films on MgO

Phenomena originated from spin-orbit interaction, such as magnetic anisotropy (MA), Rashba-type interactions, or topological insulators, have drawn huge attention for its intriguing physics. In particular, the search for a novel antiferromagnetic material, with potentially large perpendicular MA (PMA), has been becoming very intensive for next-generation high density memory applications. Here, we propose that substitutions of transition metals Ru and Ir, neighboring and same group elements in the periodic table, for the Rh site in the vicinity of surface can induce a substantially large PMA, up to an order of magnitude of 20 erg/cm2, in FeRh films on MgO. The main driving mechanism for this huge PMA is the interplay between the dxy and dx2-y2 states of strong spin-orbit 4d and 5d orbitals. Further investigations demonstrate that magnetization direction of PMA undergoes a transition into an in-plane magnetization at the antiferromagnetic-to-ferromagnetic phase transition, which provides a viable route for achieving large and switchable PMA associated with the magnetic-phase transition in antiferromagnetic spintronics.
Evidence for mixed phases and percolation at the metal-insulator transition in two dimensions

The in-plane magnetoconductance of the strongly interacting two-dimensional electron system in a silicon MOSFET (metal-oxide-semiconductor-field-effect transistor) exhibits an unmistakeable kink at a well-defined electron density, $n_k$. The kink at $n_k$ is near, but not at the critical density $n_c$ determined from resistivity measurements, and the density at which $n_k$ occurs varies with temperature. These features are inconsistent with expectations for a quantum phase transition. We suggest instead that this is a percolation transition and present a detailed model based on the formation of a mixed insulating and metallic phase within which a metal-insulator transition takes place by percolation.
Asteroseismic radii of dwarfs: new accuracy constraints from Gaia DR2 parallaxes

Precise stellar masses and radii can be determined using asteroseismology, but their accuracy must be tested against independent estimates. Using radii derived from Gaia DR2 parallaxes, we test the accuracy of asteroseismic radii for a sample of 93 dwarfs based on both individual frequency fitting and the seismic scaling relations. Radii from frequency fitting are about 1 per cent smaller than Gaia radii on average; however, this difference may be explained by a negative bias of 30 $\mu$as in the Gaia parallaxes. This indicates that the radii derived from frequency fitting are accurate to within 1 per cent. The scaling relations are found to overestimate radii by more than 5 per cent, compared to the Gaia radii, at the highest temperatures. We demonstrate that this offset is reduced to 3 per cent after applying corrections based on model frequencies to the scaling relation for $\Delta\nu$, but only when the model frequencies are corrected for the surface effect. With corrections to $\Delta\nu$, the scaling relation gives radii accurate to about 2--3 per cent for dwarfs in the temperature range $5400$--$6700$ K. The remaining offset at the highest temperatures may indicate the need for a correction to the scaling relation for $\nu_{\mathrm{max}}$.
Lack of correlation between the spin-mixing conductance and the inverse spin Hall effect generated voltages in CoFeB/Pt and CoFeB/Ta bilayers

We investigate spin pumping phenomena in polycrystalline CoFeB/Pt and CoFeB/Ta bilayers and the correlation between the effective spin mixing conductance $g^{\uparrow\downarrow}_{\rm eff}$ and the obtained voltages generated by the spin-to-charge current conversion via the inverse spin Hall effect in the Pt and Ta layers. For this purpose we measure the in-plane angular dependence of the generated voltages on the external static magnetic field and we apply a model to separate the spin pumping signal from the one generated by the spin rectification effect in the magnetic layer. Our results reveal a dominating role of anomalous Hall effect for the spin rectification effect with CoFeB and a lack of correlation between $g^{\uparrow\downarrow}_{\rm eff}$ and inverse spin Hall voltages pointing to a strong role of the magnetic proximity effect in Pt in understanding the observed increased damping. This is additionally reflected on the presence of a linear dependency of the Gilbert damping parameter on the Pt thickness.
Concerning the ghost contribution to the one-loop integrands in open string field theory

We examine the ghost contribution to the one-loop integrands in open string field theory using the Moyal representation of the star product. We primarily focus on the open string tadpole integrand, which is an intrinsically off-shell quantity. Due to the closed string tachyon, the full amplitude is badly divergent from the closed string degeneration region $t\to0^+$ of the Schwinger parameter. We obtain expansions for the finite factors from the squeezed state matrix ${\bf R}(t)$ characterizing the ghost part of the tadpole in Siegel gauge. The analytic structure of the integrands, as a function of the Schwinger parameter, captures the correct linear order behaviour near both the closed and open string degeneration limits. Using a geometric series for the matrix inverse, we obtain an approximation for the even parity matrix elements. We employ an expansion based on results from the oscillator basis to construct Pad\'e approximants to further analyse hints of non-analyticity near this limit. We also briefly discuss the evaluation of ghost integrands for the four string diagrams contributing to the one-loop $2$-point function in open string field theory.
FRICAT: A FIRST catalog of FRI radio galaxies

We built a catalog of 219 FRI radio galaxies (FRIs), called FRICAT, selected from a published sample and obtained by combining observations from the NVSS, FIRST, and SDSS surveys. We included in the catalog the sources with an edge-darkened radio morphology, redshift $\leq 0.15$, and extending (at the sensitivity of the FIRST images) to a radius $r$ larger than 30 kpc from the center of the host. We also selected an additional sample (sFRICAT) of 14 smaller (10 $<r<$ 30 kpc) FRIs, limiting to $z<0.05$. The hosts of the FRICAT sources are all luminous ($-21 \gtrsim M_r \gtrsim -24$), red early-type galaxies with black hole masses in the range $10^8 \lesssim M_{\rm BH} \lesssim 3\times10^9 M_\odot$; the spectroscopic classification based on the optical emission line ratios indicates that they are all low excitation galaxies. Sources in the FRICAT are then indistinguishable from the FRIs belonging to the Third Cambridge Catalogue of Radio Sources (3C) on the basis of their optical properties. Conversely, while the 3C-FRIs show a strong positive trend between radio and [OIII] emission line luminosity, these two quantities are unrelated in the FRICAT sources; at a given line luminosity, they show radio luminosities spanning about two orders of magnitude and extending to much lower ratios between radio and line power than 3C-FRIs. Our main conclusion is that the 3C-FRIs just represent the tip of the iceberg of a much larger and diverse population of FRIs.
Global perspective on the permanent or transitory nature of shocks to tourist arrivals: Evidence from new unit root tests with structural breaks and factors

This study extends the literature on the permanent or transitory nature of shocks to per capita tourist arrivals along several dimensions. First, the study evaluates the nature of shocks to per capita tourist arrivals for a global panel of 129 countries. Second, unlike previous studies, we jointly estimate structural changes that represent either abrupt breaks or as a Fourier approximation of smooth breaks along with introducing a factor structure to test for the presence of unit roots in per capita tourist arrivals. Third, contrary to previous studies, our results show that rejection of the null hypothesis of a unit root in per capita tourist arrivals is quite limited compared to other unit root tests that fail to account for cross-correlations. Policy implications of the findings are also discussed.
EVIDENCE FOR GAMMA-RAY EMISSION FROM THE LOW-MASS X-RAY BINARY SYSTEM FIRST J102347.6+003841

The low-mass X-ray binary (LMXB) system FIRST J102347.6+003841 hosts a newly born millisecond pulsar (MSP) PSR J1023+0038 that was revealed as the first and only known rotation-powered MSP in a quiescent LMXB. While the system is shown to have an accretion disk before 2002, it remains unclear how the accretion disk has been removed in order to reveal the radio pulsation in 2007. In this Letter, we report the discovery of γ-rays spatially consistent with FIRST J102347.6+003841, at a significance of seven standard deviations, using data obtained by the Fermi Gamma-ray Space Telescope. The γ-ray spectrum can be described by a power law (PL) with a photon index of 2.9 ± 0.2, resulting in an energy flux above 200 MeV of (5.5 ± 0.9) × 10−12 erg cm−2 s−1. The γ-rays likely originate from the MSP PSR J1023+0038, but also possibly from an intrabinary shock between the pulsar and its companion star. To complement the γ-ray study, we also re-investigate the XMM-Newton data taken in 2004 and 2008. Our X-ray spectral analysis suggests that a broken PL with two distinct photon indices describes the X-ray data significantly better than a single PL. This indicates that there exists two components and that both components appear to vary with the orbital phase. The evidence for γ-ray emission conforms with a recent suggestion that γ-rays from PSR J1023+0038 may be responsible for ejecting the disk material out of the system.