Miracle-dz/UniFAR-FTUs huggingface dataset:
Electron spin relaxation in graphene with random Rashba field: comparison of the D'yakonov–Perel' and Elliott–Yafet-like mechanisms

To understand the main spin relaxation mechanism in graphene, we investigate the spin relaxation with random Rashba field (RRF) induced by both adatoms and a substrate using the kinetic spin Bloch equation approach. The charged adatoms, on the one hand, enhance the Rashba spin–orbit coupling locally and, on the other hand, serve as Coulomb potential scatterers. Both effects contribute to spin relaxation limited by the D'yakonov–Perel' (DP) mechanism. In addition, the RRF also causes spin relaxation by spin-flip scattering, manifesting itself as an Elliott–Yafet (EY)-like mechanism. Both mechanisms are sensitive to the correlation length of the RRF, which may be affected by environmental parameters such as electron density and temperature. Fitting and comparing the experiments of the Groningen group (Józsa et al 2009 Phys. Rev. B 80 241403(R)) and the Riverside group (Pi et al 2010 Phys. Rev. Lett. 104 187201; Han and Kawakami 2011 Phys. Rev. Lett. 107 047207), which show either DP (with the spin relaxation rate being inversely proportional to the momentum scattering rate) or EY-like (with the spin relaxation rate being proportional to the momentum scattering rate) properties, we suggest that the DP mechanism dominates the spin relaxation in graphene. The latest experimental finding of a nonmonotonic dependence of spin relaxation time on diffusion coefficient by Jo et al 2011 (Phys. Rev. B 84 075453) is also well reproduced by our model.
Can Turbulence Dominate Depolarization of Optical Blazars?

We carefully examine the depolarization feature of blazars in the optical and near-infrared bands using the sample of Mead et al. Magnetohydrodynamics turbulence could be one possible reason for the depolarization of optical/infrared blazars when we apply the theoretical analysis of Lazarian & Pogosyan. We further identify in the sample that the depolarization results shown in most blazars roughly obey the form of the three-dimensional anisotropic Kolmogorov scaling. The effective Faraday rotation window length scale is not small enough to resolve the polarization correlation length scale in the blazar sample. The depolarization and the related turbulent features show diversities in different blazar sources. We suggest more simultaneous observations in both the optical/infrared and the high-energy bands for the study of the blazar polarization.
On the Ledrappier–Young formula for self-affine measures

Abstract Ledrappier and Young introduced a relation between entropy, Lyapunov exponents and dimension for invariant measures of diffeomorphisms on compact manifolds. In this paper, we show that a self-affine measure on the plane satisfies the Ledrappier–Young formula if the corresponding iterated function system (IFS) satisfies the strong separation condition and the linear parts satisfy the dominated splitting condition. We give sufficient conditions, inspired by Ledrappier and by Falconer and Kempton, that the dimensions of such a self-affine measure is equal to the Lyapunov dimension. We show some applications, namely, we give another proof for Hueter–Lalley's theorem and we consider self-affine measures and sets generated by lower triangular matrices.
A DEEP CHANDRA ACIS STUDY OF NGC 4151. III. THE LINE EMISSION AND SPECTRAL ANALYSIS OF THE IONIZATION CONE

This paper is the third in a series in which we present deep Chandra ACIS-S imaging spectroscopy of the Seyfert 1 galaxy NGC 4151, devoted to study its complex circumnuclear X-ray emission. Emission features in the soft X-ray spectrum of the bright extended emission (L0.3–2 keV ∼ 1040 erg s−1) at r > 130 pc (2″) are consistent with blended brighter O vii, O viii, and Ne ix lines seen in the Chandra HETGS and XMM-Newton RGS spectra below 2 keV. We construct emission line images of these features and find good morphological correlations with the narrow-line region clouds mapped in [O iii] λ5007. Self-consistent photoionization models provide good descriptions of the spectra of the large-scale emission, as well as resolved structures, supporting the dominant role of nuclear photoionization, although displacement of optical and X-ray features implies a more complex medium. Collisionally ionized emission is estimated to be ≲12% of the extended emission. Presence of both low- and high-ionization spectral components and extended emission in the X-ray image perpendicular to the bicone indicates leakage of nuclear ionization, likely filtered through warm absorbers, instead of being blocked by a continuous obscuring torus. The ratios of [O iii]/soft X-ray flux are approximately constant (∼15) for the 1.5 kpc radius spanned by these measurements, indicating similar relative contributions from the low- and high-ionization gas phases at different radial distances from the nucleus. If the [O iii] and X-ray emission arise from a single photoionized medium, this further implies an outflow with a wind-like density profile. Using spatially resolved X-ray features, we estimate that the mass outflow rate in NGC 4151 is ∼2 M☉ yr−1 at 130 pc and the kinematic power of the ionized outflow is 1.7 × 1041 erg s−1, approximately 0.3% of the bolometric luminosity of the active nucleus in NGC 4151.
The Y-type Brown Dwarfs: Estimates of Mass and Age from New Astrometry, Homogenized Photometry, and Near-infrared Spectroscopy

The survey of the mid-infrared sky by the Wide-field Infrared Survey Explorer (WISE) led to the discovery of extremely cold, low-mass brown dwarfs, classified as Y dwarfs, which extend the T class to lower temperatures. Twenty-four Y dwarfs are known at the time of writing. Here we present improved parallaxes for four of these, determined using Spitzer images. We give new photometry for four late-type T and three Y dwarfs and new spectra of three Y dwarfs, obtained at Gemini Observatory. We also present previously unpublished photometry taken from HST, ESO, Spitzer, and WISE archives of 11 late-type T and 9 Y dwarfs. The near-infrared data are put onto the same photometric system, forming a homogeneous data set for the coolest brown dwarfs. We compare recent models to our photometric and spectroscopic data set. We confirm that nonequilibrium atmospheric chemistry is important for these objects. Nonequilibrium cloud-free models reproduce well the near-infrared spectra and mid-infrared photometry for the warmer Y dwarfs with 425 ≤ Teff (K) ≤ 450. A small amount of cloud cover may improve the model fits in the near-infrared for the Y dwarfs with 325 ≤ Teff (K) ≤ 375. Neither cloudy nor cloud-free models reproduce the near-infrared photometry for the Teff = 250 K Y dwarf W0855. We use the mid-infrared region, where most of the flux originates, to constrain our models of W0855. We find that W0855 likely has a mass of 1.5–8 Jupiter masses and an age of 0.3–6 Gyr. The Y dwarfs with measured parallaxes are within 20 pc of the Sun and have tangential velocities typical of the thin disk. The metallicities and ages we derive for the sample are generally solar-like. We estimate that the known Y dwarfs are 3 to 20 Jupiter-mass objects with ages of 0.6–8.5 Gyr.
The Unique Predictive Value of Dynamic Assessment of Character Decoding in Reading Development of Chinese Children from Grades 1 to 2

ABSTRACT Purpose This 2-year longitudinal study examined the unique prediction of a dynamic assessment (DA) of character decoding on Chinese early reading development, and further explored whether learning potential, as assessed by DA, predicts subsequent character reading development in a sample of 135 native Mandarin-speaking Chinese students from first grade to second grade. Method Latent Growth Modeling was carried out to examine the prediction of DA administered in grade 1 for the character reading growth in Chinese children from grade 1 to 2. Growth Mixture Modeling was used to identify latent-class groups with varying learning potential based on the trial-by-trial progresses on DA, and predicted the distal outcome, Chinese character reading. Results DA uniquely predicted the final level and growth rate of character reading for Chinese children from grade 1 to 2 after controlling for traditional static predictors. Additionally, three latent groups were identified to characterize different responsiveness to graduated prompts in the DA task; the three latent groups showed significant differences in character reading over time. Conclusion The findings underscore the importance of DA in predicting Chinese children’s early reading development and the classification validity of learning potential subgroups of DA in differentiating early character reading development in Chinese children.
ON THE ORIGIN OF THE ANGULAR MOMENTUM PROPERTIES OF GAS AND DARK MATTER IN GALACTIC HALOS AND ITS IMPLICATIONS

We perform a set of non-radiative hydrodynamical simulations of merging spherical halos in order to understand the angular momentum (AM) properties of the galactic halos seen in cosmological simulations. The universal shape of AM distributions seen in simulations is found to be generically produced as a result of mergers. The universal shape is such that it has an excess of low AM material and hence cannot explain the exponential structure of disk galaxies. A resolution to this is suggested by the spatial distribution of low AM material which is found to be in the center and a conical region close to the axis of rotation. A mechanism that preferentially discards the material in the center and prevents the material along the poles from falling onto the disk is proposed as a solution. We implement a simple geometric criterion for the selective removal of low AM material and show that in order for 90% of halos to host exponential disks one has to reject at least 40% of material. Next, we explore the physical mechanisms responsible for distributing the AM within the halo during a merger. For dark matter there is an inside–out transfer of AM, whereas for gas there is an outside–in transfer, which is due to differences between collisionless and gas dynamics. This is responsible for the spin parameter λ and the shape parameter α of AM distributions being higher for gas compared to dark matter. We also explain the apparent high spin of dark matter halos undergoing mergers and show that a criterion stricter than what is currently used would be required to detect such unrelaxed halos. Finally, we demonstrate that the misalignment of AM between gas and dark matter only occurs when the intrinsic spins of the merging halos are not aligned with the orbital AM of the system. The self-misalignment (orientation of AM when measured in radial shells not being constant), which could be the cause of warps and anomalous rotation in disks galaxies, also occurs under similar conditions. The frequency and amplitude of this misalignment are roughly consistent with the properties of warps seen in disk galaxies.
Very low-mass stellar content of the young supermassive Galactic star cluster Westerlund 1

We present deep near-infrared HST/WFC3 observations of the young supermassive Galactic star cluster Westerlund 1 and an adjacent control field. The depth of the data is sufficient to derive the mass function for the cluster as a function of radius down to 0.15 M ⊙ in the outer parts of the cluster. We identify for the first time a flattening in the mass function (in logarithmic units) at a mass range that is consistent with that of the field and nearby embedded clusters. Through log-normal functional fits to the mass functions we find the nominal peak mass to be comparable to that of the field and nearby embedded star clusters. The width of a log-normal fit appears slightly narrow compared to the width of the field initial mass function, closer to the values found for globular clusters. The subsolar content within the cluster does not appear to be mass segregated in contrast to the findings for the supersolar content. The total mass of Westerlund 1 is estimated to be 44–57 × 10 3 M ⊙ where the main uncertainty is the choice of the isochrone age and the higher mass slope. Comparing the photometric mass with the dynamically determined mass, Westerlund 1 is sufficiently massive to remain bound and could potentially evolve into a lowmass globular cluster.
DISCOVERY OF A SIGNIFICANT MAGNETIC CATACLYSMIC VARIABLE POPULATION IN THE LIMITING WINDOW

We have discovered 10 periodic X-ray sources from the 1 Ms Chandra ACIS observation of the Limiting Window (LW), a low-extinction region (AV ∼ 3.9) at 1. °4 south of the Galactic center. The observed periods (∼1.3–3.4 hr) and the X-ray luminosities (1031.8–32.9 erg s−1 at 8 kpc) of the 10 periodic sources, combined with the lack of bright optical counterparts and thus high X-ray-to-optical flux ratios, suggest that they are likely accreting binaries, in particular, magnetic cataclysmic variables (MCVs). All of them exhibit a relatively hard X-ray spectrum (Γ < 2 for a power-law model), and relatively high extinction observed in the X-ray spectra of at least five sources indicates some intrinsic absorption in the system, which is also a typical sign of MCVs. On close inspection, the period distribution of these sources resembles those of polars, whereas the relatively hard spectra suggest that they could be intermediate polars (IPs). These puzzling properties can be explained by unusual polars with buried magnetic fields or a rare sub-class of MCVs, nearly synchronous MCVs. These unusual MCVs may provide important clues in the evolutionary path of MCVs from IPs to polars. The completeness simulation indicates that ≳40% of the hard X-ray sources in the LW are periodic. Therefore, this discovery provides a first direct evidence of a large MCV population in the bulge and further supports the current view that MCVs constitute the majority of low-luminosity hard X-ray sources (∼1030–33 erg s−1) in the bulge.
Two timescale analysis of extreme mass ratio inspirals in Kerr. I. Orbital Motion

Inspirals of stellar-mass compact objects into massive black holes are an important source for future gravitational wave detectors such as Advanced LIGO and LISA. The detection and analysis of these signals rely on accurate theoretical models of the binary dynamics. We cast the equations describing binary inspiral in the extreme mass ratio limit in terms of action-angle variables, and derive properties of general solutions using a two-timescale expansion. This provides a rigorous derivation of the prescription for computing the leading order orbital motion. As shown by Mino, this leading order or adiabatic motion requires only knowledge of the orbit-averaged, dissipative piece of the self-force. The two-timescale method also gives a framework for calculating the post-adiabatic corrections. For circular and for equatorial orbits, the leading order corrections are suppressed by one power of the mass ratio, and give rise to phase errors of order unity over a complete inspiral through the relativistic regime. These post-1-adiabatic corrections are generated by the fluctuating, dissipative piece of the first order self-force, by the conservative piece of the first order self-force, and by the orbit-averaged, dissipative piece of the second order self-force. We also sketch a two-timescale expansion of the Einstein equation, and deduce anmore » analytic formula for the leading order, adiabatic gravitational waveforms generated by an inspiral. « less
THE SOLAR MINIMUM CORONA FROM DIFFERENTIAL EMISSION MEASURE TOMOGRAPHY

We present results derived from a dual-spacecraft tomographic reconstruction of the solar corona's three-dimensional (3D) extreme ultraviolet (EUV) emissivity. We use simultaneously taken STEREO A and B spacecraft EUVI images from Carrington rotation 2077 (UT 2008 November 20 06:56 through UT December 17 14:34). During this period, the spacecraft view angles were separated by an average 85. °4 which allowed for the reconstruction to be performed with data gathered in about 3/4 of a full solar rotational time. The EUV reconstructions provide the 3D emissivity in each of the three EUVI Fe bands, in the range of heights 1.00–1.25 Rs. We use this information to perform local differential emission measure (LDEM) analysis. Taking moments of the so-derived LDEM distributions gives the 3D values of the electron density, temperature, and temperature spread. We determine relationships between the moments of the LDEM and the coronal magnetic field by making longitudinal averages of the moments, and relating them to the global-scale structures of a potential field source surface magnetic field model. In this way, we determine how the electron density, mean temperature, and temperature spread vary for different coronal structures. We draw conclusions about the relationship between the LDEM moments and the sources of the fast and slow solar winds, and the transition between the two regimes.
Exotic Hadrons and Underlying Z2,3 Symmetries

The recent observation of higher quark combinations, tetraquarks and pentaquarks, is a strong indication of more exotic hadrons. Using Z2 and Z3 symmetries and standard model data, a general quark combination producing new hadronic states is proposed in terms of polygon geometries according to the Dynkin diagrams of Ân affine Lie algebras. It has been shown that Z2,3 invariance is crucial in the determination of the mesonic or the baryonic nature of these states. The hexagonal geometry is considered in some details producing both mesonic and baryonic states. A general class of this family is also presented.
Income and Happiness: a Philippine Context

This paper adds to the relatively scant developing country perspective in the economic literature on happiness by investigating the relationship between income and happiness in the context of Koronadal, a low-income city in Mindanao, Philippines. Subjective happiness and potential contributory factors to happiness (demographic, economic, and social capital variables) are elicited through a survey and analyzed using descriptive and regression analyses. The study provides empirical evidence for the “happy poor” image of the Filipinos, with its survey data revealing that despite high poverty incidence and generally low-income levels, people in Koronadal are pretty happy with a mean self-reported happiness score of 6.75 on a scale of 0–10. The study also lends some empirical support to the modified Easterlin hypothesis: an increase in income increases happiness marginally, but there exists a threshold level – a monthly income of about PHP 20,000 – beyond which further increase in income ceases to increase happiness. Further, survey data reveal that happier people are younger, female, possessing a mobile phone, living in houses with more bedrooms, with savings and no outstanding loans, and are members of credit cooperatives. In so far as these findings reveal some socially favorable economic and institutional conditions, they serve to provide inputs and directions to government officials and policymakers in terms of social programs formulation and implementation.
Type 1 AGN at low z – III. The optical narrow-line ratios

We present the optical narrow line ratios in an SDSS based sample of 3,175 broad Ha selected type 1 AGN, and explore their positions in the BPT diagrams as a function of the AGN and the host properties. We find the following: 1. The luminosities of all measured narrow lines (Ha, Hb, [OIII], [NII], [SII], [OI]) show a Baldwin relation relative to the broad Ha luminosity L_bHa, with slopes in the range of 0.53-0.72. 2. About 20% of the type 1 AGN reside within the `Composite' and `SF' regions of the BPT diagrams. These objects also show excess narrow Ha and UV luminosities, for their L_bHa, consistent with contribution from star formation which dominates the narrow lines emission, as expected from their positions in the BPT diagrams. 3. The type 1 which reside within the AGN region in the BPT diagrams, are offset to lower [SII]/Ha and [NII]/Ha luminosity ratios, compared to type 2 AGN. This offset is a selection effect, related to the lower AGN/host luminosity selection of the type 2 AGN selected from the SDSS galaxy sample. 4. The [NII]/Ha and [NII]/[SII] ratios in type 1 AGN increase with the host mass, as expected if the mass-metallicity relation of quiescent galaxies holds for the AGN narrow line region. 5. The broad lines optical FeII is higher for a higher [NII]/Ha, at a fixed L_Bol and Eddington ratio L/L_Edd. This suggests that the broad line region metallicity is also related to the host mass. 6. The fraction of AGN which are LINERs increases sharply with decreasing L/L_Edd. This fraction is the same for type 1 and type 2 AGN. 7. The BPT position is unaffected by the amount of dust extinction of the optical-UV continuum, which suggests the extincting dust resides on scales larger than the NLR.
The Star Formation in the L1615/L1616 Cometary Cloud

The present work aims at performing a comprehensive census and characterization of the pre-main-sequence (PMS) population in the cometary cloud L1615/L1616, in order to assess the significance of the triggered star formation scenario and investigate the impact of massive stars on its star formation history and mass spectrum. Our study is based on UBVRCIC and JHKs photometry, as well as optical multiobject spectroscopy. We performed a physical parameterization of the young stellar population in L1615/L1616. We identified 25 new T Tauri stars mainly projected on the dense head of the cometary cloud, almost doubling the current number of known members. We studied the spatial distribution of the cloud members as a function of the age and Hα emission. The star formation efficiency (SFE) in the cloud is ~7%-8%, as expected for molecular clouds in the vicinity of OB associations. The slope of the initial mass function (IMF), in the mass range 0.1 M☉ ⩽ M ⩽ 5.5 M☉, is consistent with that of other T and OB associations, providing further support of a universal IMF down to the hydrogen-burning limit, regardless of environmental conditions. The cometary appearance, as well as the high SFE, can be explained in terms of triggered star formation induced by the strong UV radiation from OB stars or supernova shock waves. The age spread and both the spatial and age distribution of the PMS objects provide strong evidence of sequential, multiple events and possibly still ongoing star formation activity in the cloud.
Magnetic field amplification and magnetically supported explosions of collapsing, non-rotating stellar cores

We study the amplification of magnetic fields in the collapse and the post-bounce evolution of the core of a non-rotating star of 15 solar masses in axisymmetry. To this end, we solve the coupled equations of magnetohydrodynamics and neutrino transport in the two-moment approximation. The pre-collapse magnetic field is strongly amplified by compression in the infall. Initial fields of the order of 1010 G translate into proto-neutron star fields similar to the ones observed in pulsars, while stronger initial fields yield magnetar-like final field strengths. After core bounce, the field is advected through the hydrodynamically unstable neutrino-heating layer, where non-radial flows due to convection and the standing accretion shock instability amplify the field further. Consequently, the resulting amplification factor of order five is the result of the number of small-eddy turnovers taking place within the time scale of advection through the post-shock layer. Due to this limit, most of our models do not reach equipartition between kinetic and magnetic energy and, consequently, evolve similarly to the non-magnetic case, exploding after about 800 ms when a single or few high-entropy bubbles persist over several dynamical time scales. In the model with the strongest initial field we studied, \$10^{12}\$ G, for which equipartition between flow and field is achieved, the magnetic tension favours a much earlier development of such long-lived high-entropy bubbles and enforces a fairly ordered large-scale flow pattern. Consequently, this model, after exhibiting very regular shock oscillations, explodes much earlier than non-magnetic ones.