Miracle-dz/UniFAR-FTUs huggingface dataset:
Comparing extrapolations of the coronal magnetic field structure at 2.5R⊙with multi-viewpoint coronagraphic observations

The magnetic field shapes the structure of the solar corona, but we still know little about the interrelationships between the coronal magnetic field configurations and the resulting quasi-stationary structures observed in coronagraphic images (such as streamers, plumes, and coronal holes). One way to obtain information on the large-scale structure of the coronal magnetic field is to extrapolate it from photospheric data and compare the results with coronagraphic images. Our aim is to verify whether this comparison can be a fast method to systematically determine the reliability of the many methods that are available for modeling the coronal magnetic field. Coronal fields are usually extrapolated from photospheric measurements that are typically obtained in a region close to the central meridian on the solar disk and are then compared with coronagraphic images at the limbs, acquired at least seven days before or after to account for solar rotation. This implicitly assumes that no significant changes occurred in the corona during that period. In this work, we combine images from three coronagraphs (SOHO/LASCO-C2 and the two STEREO/SECCHI-COR1) that observe the Sun from different viewing angles to build Carrington maps that cover the entire corona to reduce the effect of temporal evolution to about five days. We then compare the position of the observed streamers in these Carrington maps with that of the neutral lines obtained from four different magnetic field extrapolations to evaluate the performances of the latter in the solar corona. Our results show that the location of coronal streamers can provide important indications to distinguish between different magnetic field extrapolations.
Polymorphous nature of cubic halide perovskites

It has been long known that numerous halide and oxide perovskites can have non-ideal octahedra, showing tilting, rotation, and metal atom displacements. It has also been known that compounds that have at low temperatures a single structural motif ("monomorphous structures") could become disordered at higher temperatures, resulting in non-ideal octahedra as an entropy effect. What is shown here is that in many cubic halide perovskites and some oxides compounds a distribution of different low-symmetry octahedra ("polymorphous networks") emerge already from the minimization of the systems internal energy, i.e., they represent the intrinsic, preferred low temperature pattern of chemical bonding. Thermal disorder effects build up at elevated temperatures on top of such low temperature polymorphous networks. Compared with the monomorphous counterparts, the polymorphous networks have lower predicted total energies (enhanced stability), larger band gaps and dielectric constants now dominated by the ionic part, and agrees much more closely with the observed pair distribution functions. The nominal cubic perovskites (Pm-3m) structure deduced from X-Ray diffraction is actually a macroscopically averaged, high symmetry configuration, which should not be used to model electronic properties, given that the latter reflect a low symmetry local configuration.
A particular carbon-chain-producing region: L1489 starless core

We detected carbon-chain molecules (CCMs) HC2n+1N (n = 1−3) and C3S in Ku band as well as high-energy excitation lines including C4H N = 9–8, J = 17/2–15/2, 19/2–17/2, and CH3CCH J = 5–4, K = 2 in the 3 mm band toward a starless core called the eastern molecular core (EMC) of L1489 IRS. Maps of all the observed lines were also obtained. Comparisons with a number of early starless cores and the warm carbon-chain chemistry (WCCC) source L1527 show that the column densities of C4H and CH3CCH are close to those of L1527, and the CH3CCH column densities of the EMC and L1527 are slightly higher than those of TMC-1. The EMC and L1527 have similar C3S column densities, but they are much lower than those of all the starless cores, with only 6.5 and 10% of the TMC-1 value, respectively. The emissions of the N-bearing species of the EMC and L1527 are at the medium level of the starless cores. These comparisons show that the CCM emissions in the EMC are similar to those of L1527, though L1527 contains a protostar. Although dark and quiescent, the EMC is warmer and at a later evolutionary stage than classical carbon-chain–producing regions in the cold, dark, quiescent early phase. The PACS, SPIRE, and SCUBA maps evidently show that the L1489 IRS seems to be the heating source of the EMC. Although it is located at the margins of the EMC, its bolometric luminosity and bolometric temperature are relatively high. Above all, the EMC is a rather particular carbon-chain-producing region and is quite significant for CCM science.
Absolute frequency measurement of rubidium 
5S−6P
 transitions

We report on measurements of the $5S\text{\ensuremath{-}}6P$ rubidium transition frequencies for rubidium isotopes with an absolute uncertainty of $\ensuremath{\le}20\phantom{\rule{0.28em}{0ex}}\mathrm{kHz}$ for the $5S\ensuremath{\rightarrow}\phantom{\rule{0.16em}{0ex}}6{P}_{3/2}$ transition and better than $20\phantom{\rule{0.28em}{0ex}}\mathrm{MHz}$ for the $5S\ensuremath{\rightarrow}\phantom{\rule{0.16em}{0ex}}6{P}_{1/2}$ transition, achieved by saturated absorption spectroscopy. From the results we derive the hyperfine splitting with an accuracy of $30\phantom{\rule{0.28em}{0ex}}\mathrm{kHz}$ and $450\phantom{\rule{0.28em}{0ex}}\mathrm{kHz}$, respectively. This is an improvement of two orders of magnitude for the $5S\ensuremath{\rightarrow}6{P}_{3/2}$ transition to the current state of the art. We also verify the literature values for the $5S\ensuremath{\rightarrow}\phantom{\rule{0.16em}{0ex}}6{P}_{1/2}$ transition, the isotope shifts, as well as the magnetic dipole constants and the electric quadrupole constants.
Ultra-low magnetic damping in Co 2 Mn-based Heusler compounds: promising materials for spintronic

The prediction of ultra-low magnetic damping in Co 2 MnZ Heusler half-metal thin-film magnets is explored in this study and the damping response is shown to be linked to the underlying electronic properties. By substituting the Z elements in high crystalline quality films (Co 2 MnZ with Z=Si, Ge, Sn, Al, Ga, Sb), electronic properties such as the minority spin band gap, Fermi energy position in the gap and spin polarization can be tuned and the consequence on magnetization dynamics analyzed. The experimental results allow us to directly explore the interplay of spin polarization, spin gap, Fermi energy position and the magnetic damping obtained in these films, together with ab initio calculation predictions. The ultra-low magnetic damping coefficients measured in the range 4.1 10-4-9 10-4 for Co 2 MnSi, Ge, Sn, Sb are the lowest values obtained on a conductive layer and offers a clear experimental demonstration of theoretical predictions on Half-Metal Magnetic Heusler compounds and a pathway for future materials design.
The Effect of 3D Transport-induced Disequilibrium Carbon Chemistry on the Atmospheric Structure, Phase Curves, and Emission Spectra of Hot Jupiter HD 189733b

On hot Jupiter exoplanets, strong horizontal and vertical winds should homogenize the abundances of the important absorbers CH4 and CO much faster than chemical reactions restore chemical equilibrium. This effect, typically neglected in general circulation models (GCMs), has been suggested to explain discrepancies between observed infrared light curves and those predicted by GCMs. On the nightsides of several hot Jupiters, GCMs predict outgoing fluxes that are too large, especially in the Spitzer 4.5 μm band. We modified the SPARC/MITgcm to include disequilibrium abundances of CH4, CO, and H2O by assuming that the CH4/CO ratio is constant throughout the simulation domain. We ran simulations of hot Jupiter HD 189733b with eight CH4/CO ratios. In the more likely CO-dominated regime, we find temperature changes ≥50–100 K compared to the simulation for equilibrium chemistry across large regions. This effect is large enough to affect predicted emission spectra and should thus be included in GCMs of hot Jupiters with equilibrium temperatures between 600 and 1300 K. We find that spectra in regions with strong methane absorption, including the Spitzer 3.6 and 8 μm bands, are strongly impacted by disequilibrium abundances. We expect chemical quenching to result in much larger nightside fluxes in the 3.6 μm band, in stark contrast to observations. Meanwhile, we find almost no effect on predicted observations in the 4.5 μm band, because the changes in opacity due to CO and H2O offset each other. We thus conclude that disequilibrium carbon chemistry cannot explain the observed low nightside fluxes in the 4.5 μm band.
Maximum Entropy-Regularized Multi-Goal Reinforcement Learning

In Multi-Goal Reinforcement Learning, an agent learns to achieve multiple goals with a goal-conditioned policy. During learning, the agent first collects the trajectories into a replay buffer, and later these trajectories are selected randomly for replay. However, the achieved goals in the replay buffer are often biased towards the behavior policies. From a Bayesian perspective, when there is no prior knowledge about the target goal distribution, the agent should learn uniformly from diverse achieved goals. Therefore, we first propose a novel multi-goal RL objective based on weighted entropy. This objective encourages the agent to maximize the expected return, as well as to achieve more diverse goals. Secondly, we developed a maximum entropy-based prioritization framework to optimize the proposed objective. For evaluation of this framework, we combine it with Deep Deterministic Policy Gradient, both with or without Hindsight Experience Replay. On a set of multi-goal robotic tasks of OpenAI Gym, we compare our method with other baselines and show promising improvements in both performance and sample-efficiency.
The Globular Cluster Origin of the Milky Way Outer Bulge: Evidence from Sodium Bimodality

Recent investigations of the double red clump in the color–magnitude diagram of the Milky Way bulge cast serious doubts on the structure and formation origin of the outer bulge. Unlike previous interpretation based on an X-shaped bulge, stellar evolution models and CN-band observations have suggested that this feature is another manifestation of the multiple stellar population phenomenon observed in globular clusters (GCs). This new scenario requires a significant fraction of the outer bulge stars with chemical patterns uniquely observed in GCs. Here we show from homogeneous high-quality spectroscopic data that the red giant branch stars in the outer bulge (>5.°5 from the Galactic center) are clearly divided into two groups according to Na abundance in the [Na/Fe]−[Fe/H] plane. The Na-rich stars are also enhanced in Al, while the differences in O and Mg are not observed between the two Na groups. The population ratio and the Na and Al differences between the two groups are also comparable with those observed in metal-rich GCs. The only plausible explanation for these chemical patterns and characteristics appears to be that the outer bulge was mostly assembled from disrupted proto-GCs in the early history of the Milky Way.
Bridging Stereo Matching and Optical Flow via Spatiotemporal Correspondence

Stereo matching and flow estimation are two essential tasks for scene understanding, spatially in 3D and temporally in motion. Existing approaches have been focused on the unsupervised setting due to the limited resource to obtain the large-scale ground truth data. To construct a self-learnable objective, co-related tasks are often linked together to form a joint framework. However, the prior work usually utilizes independent networks for each task, thus not allowing to learn shared feature representations across models. In this paper, we propose a single and principled network to jointly learn spatiotemporal correspondence for stereo matching and flow estimation, with a newly designed geometric connection as the unsupervised signal for temporally adjacent stereo pairs. We show that our method performs favorably against several state-of-the-art baselines for both unsupervised depth and flow estimation on the KITTI benchmark dataset.
A Bayesian direct method implementation to fit emission line spectra: application to the primordial He abundance determination

This work presents a Bayesian algorithm to fit the recombination and collisionally excited line spectra of gas photoionized by clusters of young stars. The current model consists of 14 dimensions: two electron temperatures, one electron density, the extinction coefficient, the optical depth on the $\rm He\, \small {I}$ recombination lines, and nine ionic species. The results are in very good agreement with those previously published using the traditional methodology. The probabilistic programming library pymc3 was chosen to explore the parameter space via an NUTs sampler. These machine learning tools provided excellent convergence quality and speed. The primordial helium abundance measured from a multivariable regression using oxygen, nitrogen, and sulfur was $Y_{\mathrm{ P},\, \mathrm{ O}\! -\! \mathrm{ N}\! -\! \mathrm{ S}}=0.243\pm 0.005$ in agreement with a standard Big Bang scenario.
Early age-related changes in episodic memory retrieval as revealed by event-related potentials

Familiarity is better preserved than recollection in ageing. The age at which changes first occur and the slope of the subsequent decline, however, remain unclear. In this study, we investigated changes in episodic memory, by using event-related potentials (ERPs) in young (m=24), middle-aged (m=58) and older (m=70) adults. Although behavioural performance did not change before the age of 65 years, changes in ERP correlates were already present in the middle-aged adults. The ERP correlates of recollection and monitoring processes were the first to be affected by ageing, with a linear decrease as age increased. Conversely, the ERP correlate of familiarity remained unchanged, at least up to the age of 65 years. These results suggest a differential time course for the age effects on episodic retrieval.
Spatially Resolved Stellar Populations and Kinematics with KCWI: Probing the Assembly History of the Massive Early-type Galaxy NGC 1407

Using the newly commissioned Keck Cosmic Web Imager (KCWI) instrument on the Keck II telescope, we analyze the stellar kinematics and stellar populations of the well-studied massive early-type galaxy (ETG) NGC 1407. We obtained high signal-to-noise integral field spectra for a central and an outer (around one effective radius toward the southeast direction) pointing with integration times of just 600 s and 2400 s, respectively. We confirm the presence of a kinematically distinct core also revealed by VLT/MUSE data of the central regions. While NGC 1407 was previously found to have stellar populations characteristic of massive ETGs (with radially constant old ages and high alpha-enhancements), it was claimed to show peculiar supersolar metallicity peaks at a large radius that deviated from an otherwise strong negative metallicity gradient, which is hard to reconcile within a “two-phase” formation scenario. Our outer pointing confirms the near-uniform old ages and the presence of a steep metallicity gradient, but with no evidence for anomalously high metallicity values at large galactocentric radii. We find a rising outer velocity dispersion profile and high values of the fourth-order kinematic moment—an indicator of possible anisotropy. This coincides with the reported transition from a bottom-heavy to a Salpeter initial mass function, which may indicate that we are probing the transition region from the “in situ” to the accreted phase. With short exposures, we have been able to derive robust stellar kinematics and stellar populations in NGC 1407 to ∼1 effective radius. This experiment shows that future work with KCWI will enable 2D kinematics and stellar populations to be probed within the low surface brightness regions of galaxy halos in an effective way.
Opportunistic Temporal Fair Mode Selection and User Scheduling for Full-duplex Systems

In-band full-duplex (FD) communications - enabled by recent advances in antenna and RF circuit design - has emerged as one of the promising techniques to improve data rates in wireless systems. One of the major roadblocks in enabling high data rates in FD systems is the inter-user interference (IUI) due to activating pairs of uplink and downlink users at the same time-frequency resource block. Opportunistic user scheduling has been proposed as a means to manage IUI and fully exploit the multiplexing gains in FD systems. In this paper, scheduling under long-term and short-term temporal fairness for single-cell FD wireless networks is considered. Temporal fair scheduling is of interest in delay-sensitive applications, and leads to predictable latency and power consumption. The feasible region of user temporal demand vectors is derived, and a scheduling strategy maximizing the system utility while satisfying long-term temporal fairness is proposed. Furthermore, a short-term temporal fair scheduling strategy is devised which satisfies user temporal demands over a finite window-length. It is shown that the strategy achieves optimal average system utility as the window-length is increased asymptotically. Subsequently, practical construction algorithms for long-term and shortterm temporal fair scheduling are introduced. Simulations are provided to verify the derivations and investigate the multiplexing gains. It is observed that using successive interference cancellation at downlink users improves FD gains significantly in the presence of strong IUI.
Non-homogeneous thermal transport in graphene disk at the micro/nano scale.

A novel non-homogeneous or graded thermal conductivity along the radius direction in a single graphene disk structure has been predicted in previous study by using classical non-equilibrium molecular dynamics method. However, the size of the simulated system was only up to 25 nm due to the limitation of computational method. So whether the graded thermal conductivity phenomena can be observed over hundreds of nanometers is an open question need to be answered. In this work, the thermal conductivity of graphene disk is studied from nano scale up to micro scale based on the phonon Boltzmann transport equation (BTE) under Callaway's dual relaxation model. The results show that the graded thermal conductivity phenomena exist along the radius direction as the disk size increases from hundreds of nanometers to tens of microns. In the ballistic regime, the numerical results are in excellent agreement with our derived analytical solutions. As the system size is much larger than the phonon mean free path, the moment conservation normal (N) scattering leads to a diverging thermal conductivity and generates a drift velocity along the radius direction nearly inversely proportional to the radius. It is different from the moment destroying resistive (R) scattering which recovers the traditional Fourier's law of thermal conduction. Furthermore, as the system size increases, the graded rate of the thermal conductivity increases for N scattering but decreases for R scattering.
A Quick Introduction to Functional Verification of Array-Intensive Programs

Array-intensive programs are often amenable to parallelization across many cores on a single machine as well as scaling across multiple machines and hence are well explored, especially in the domain of high-performance computing. These programs typically undergo loop transformations and arithmetic transformations in addition to parallelizing transformations. Although a lot of effort has been invested in improving parallelizing compilers, experienced programmers still resort to hand-optimized transformations which is typically followed by careful tuning of the transformed program to finally obtain the optimized program. Therefore, it is critical to verify that the functional correctness of an original sequential program is not sacrificed during the process of optimization. In this paper, we cover important literature on functional verification of array-intensive programs which we believe can be a good starting point for one interested in this field.
Domain adaptation for part-of-speech tagging of noisy user-generated text

The performance of a Part-of-speech (POS) tagger is highly dependent on the domain of the processed text, and for many domains there is no or only very little training data available. This work addresses the problem of POS tagging noisy user-generated text using a neural network. We propose an architecture that trains an out-of-domain model on a large newswire corpus, and transfers those weights by using them as a prior for a model trained on the target domain (a data-set of German Tweets) for which there is very little annotations available. The neural network has a standard bidirectional LSTM at its core. However, we find it crucial to also encode a set of task-specific features, and to obtain reliable (source-domain and target-domain) word representations. Experiments with different regularization techniques such as early stopping, dropout and fine-tuning the domain adaptation prior weights are conducted. Our best model uses external weights from the out-of-domain model, as well as feature embeddings, pre-trained word and sub-word embeddings and achieves a tagging accuracy of slightly over 90%, improving on the previous state of the art for this task.
Non-canonical scalar field in low anisotropy universe with intermediate inflation.

The behaviour of a non-canonical scalar field within an anisotropic Bianchi type I, spatially homogeneous, Universe in the framework of the intermediate inflation will be studied. It will be examined on the condition that both the anisotropy and non-canonical sources come together and is there any improvement in compatibility with the observational data originated from plank $2015$? Based on this investigation it can be observed that automatically a steep potential which can manage inflation in a better way will be obtained. Additionally, as a common procedure for an inflationary study, we shall try to calculate the related inflationary observables such as the amplitude of the scalar perturbations, scalar and tensor spectral indices, tensor-to-scalar ratio, the running spectral index, and the number of e-folds. As an exciting part of our results, we will find that our model has a good consistency compared to data risen by CMB and different Planck results. To justify our claims, the well known canonical inflationary scenario in an anisotropic Bianchi type I Universe also will be evaluated.
Parallel Reachability in Almost Linear Work and Square Root Depth

In this paper we provide a parallel algorithm that given any n-node m-edge directed graph and source vertex s computes all vertices reachable from s with Õ(m) work and n^{1/2 + o(1)} depth with high probability in n. This algorithm also computes a set of Õ(n) edges which when added to the graph preserves reachability and ensures that the diameter of the resulting graph is at most n^{1/2 + o(1)}. Our result improves upon the previous best known almost linear work reachability algorithm due to Fineman [1] which had depth Õ(n^2/3). Further, we show how to leverage this algorithm to achieve improved distributed algorithms for single source reachability in the CONGEST model. In particular, we provide a distributed algorithm that given a n-node digraph of undirected hop-diameter D solves the single source reachability problem with Õ(n^1/2 + n^1/3+o(1) D^2/3) rounds of the communication in the congest~model with high probability in n. Our algorithm is nearly optimal whenever D = O(n^1/4-ε) for any constant ε > 0 and is the first nearly optimal algorithm for general graphs whose diameter is Ω(n^δ) for any constant δ.