ShantanuT01/DACTYL-Pretraining huggingface dataset:
The intrinsically anti-ferromagnetic topological insulator, MnBi$_2$Te$_4$ (MBT), has garnered significant attention recently. The excitement for this layered van der Waals bonded compound stems from its potential to host numerous exotic topological quantum states. For instance, quantum anomalous Hall states are predicted for odd-layer compounds and axion insulator states for the even-layer compounds. Unfortunately, the realization of these phenomena has been hindered by experimental challenges such as the existence of negative charge carriers, i.e., electron doping, which have been linked to anti-site defects among the Mn and Bi sub-lattices. Based on high level diffusion Monte Carlo (DMC) and DMC-tuned DFT+U calculations, we provide benchmark quality results for the bulk Mn magnetization as well as for Mn$_{Bi}$ and Bi$_{Mn}$ defects. We use this information to refine and extend models that estimate the anti-site defect concentration in actual MBT samples when combined with data from magnetic susceptibility and intermediate field magnetization measurements. Our models are validated through favorable comparison with prior experimental studies that obtained both magnetic and site occupancy data. We then extend our estimates to a larger set of prior samples to identify a probable zone of low defect density that has yet to be reached in synthesis. We anticipate our theoretically based magnetic purity measures may be used as minimization targets in the cycle of refinement needed to synthesize MBT samples with low anti-site defect concentrations and more reproducible topological properties.
Interactive video object segmentation (iVOS) aims at efficiently harvesting high-quality segmentation masks of the target object in a video with user interactions. Most previous state-of-the-arts tackle the iVOS with two independent networks for conducting user interaction and temporal propagation, respectively, leading to inefficiencies during the inference stage. In this work, we propose a unified framework, named Memory Aggregation Networks (MA-Net), to address the challenging iVOS in a more efficient way. Our MA-Net integrates the interaction and the propagation operations into a single network, which significantly promotes the efficiency of iVOS in the scheme of multi-round interactions. More importantly, we propose a simple yet effective memory aggregation mechanism to record the informative knowledge from the previous interaction rounds, improving the robustness in discovering challenging objects of interest greatly. We conduct extensive experiments on the validation set of DAVIS Challenge 2018 benchmark. In particular, our MA-Net achieves the J@60 score of 76.1% without any bells and whistles, outperforming the state-of-the-arts with more than 2.7%.
In this article, we investigate the possibility of approximating the physical inner product of constrained quantum theories. In particular, we calculate the physical inner product of a simple cosmological model in two ways: Firstly, we compute it analytically via a trick, secondly, we use the complexifier coherent states to approximate the physical inner product defined by the master constraint of the system. We will find that the approximation is able to recover the analytic solution of the problem, which solidifies hopes that coherent states will help to approximate solutions of more complicated theories, like loop quantum gravity.
Barocaloric effect in vulcanized natural rubber (V-NR) has been investigated. Direct measurements of the temperature change ({\Delta}T) around room temperature (283-333 K) resulted in large values, above 10 K, for a pressure change of 173 MPa. A power law was proposed to fit {\Delta}T as function of the maximum pressure, showing to be suitable for the barocaloric effect in V-NR. Strain was measured as a function of temperature at constant pressures in order to obtain the isothermal entropy change ({\Delta}ST). At 293 K, we obtained a {\Delta}ST of 21 J.kg-1K-1 for a pressure change of only 43.4 MPa. The results presented in this work are compared with those reported recently for PVDF-TrFE-CTFE polymer, showing a better barocaloric performance for V-NR in similar temperature and pressure ranges. These findings evidence the high potential of V-NR for application in solid-state refrigeration based on confined compression, opening new possibilities for i-caloric materials.
As a prototype of powerful non-abelian symmetry in an Integrable System, I will show the appearance of a Witt algebra of vector fields in the SG theory. This symmetry does not share anything with the well-known Virasoro algebra of the conformal $c=1$ unperturbed limit. Although it is quasi-local in the SG field theory, nevertheless it gives rise to a local action on $N$-soliton solution variables. I will explicitly write the action on special variables, which possess a beautiful geometrical meaning and enter the Form Factor expressions of quantum theory. At the end, I will also give some preliminary hints about the quantisation.
This is a review of the aspirations and disappointments of the canonical quantization of geometry. I compare the two chief ways of looking at canonical gravity, geometrodynamics and connection dynamics. I capture as much of the classical theory as I can by pictorial visualization. Algebraic aspects dominate my description of the quantization program. I address the problem of observables. The reader is encouraged to follow the broad outlines and not worry about the technical details.
SECIS observations of the June 2001 total solar eclipse were taken using an Fe {\sc xiv} 5303 {\AA} filter. Automated tools based on wavelet analysis was used to detect intensity oscillations on various areas of the images. Statistical analysis of the detections found in the areas covered by the moon and the upper corona allowed us to estimate the atmospheric and instrumental effects on the detection of intensity oscillations. An area of the lower corona, close to Active Region 9513, was found with a statistically significant amount of intensity oscillations with periodicity of $\sim7.5s$. The shape of the wavelet transformation of those detections matches theoretical predictions of sausage-mode perturbations and for the first time in the SECIS project, second order oscillations were also detected.
Classical novae are caused by mass transfer episodes from a main sequence star onto a white dwarf via Roche lobe overflow. This material forms an accretion disk around the white dwarf. Ultimately, a fraction of this material spirals in and piles up on the white dwarf surface under electron-degenerate conditions. The subsequently occurring thermonuclear runaway reaches hundreds of megakelvin and explosively ejects matter into the interstellar medium. The exact peak temperature strongly depends on the underlying white dwarf mass, the accreted mass and metallicity, and the initial white dwarf luminosity. Observations of elemental abundance enrichments in these classical nova events imply that the ejected matter consists not only of processed solar material from the main sequence partner but also of material from the outer layers of the underlying white dwarf. This indicates that white dwarf and accreted matter mix prior to the thermonuclear runaway. The processes by which this mixing occurs require further investigation to be understood. In this work, we analyze elemental abundances ejected from hydrodynamic nova models in search of elemental abundance ratios that are useful indicators of the total amount of mixing. We identify the abundance ratios $\Sigma$CNO/H, Ne/H, Mg/H, Al/H, and Si/H as useful mixing meters in ONe novae. The impact of thermonuclear reaction rate uncertainties on the mixing meters is investigated using Monte Carlo post-processing network calculations with temperature-density evolutions of all mass zones computed by the hydrodynamic models. We find that the current uncertainties in the $^{30}$P($p$,$\gamma$)$^{31}$S rate influence the Si/H abundance ratio, but overall the mixing meters found here are robust against nuclear physics uncertainties. A comparison of our results with observations of ONe novae provides strong constraints for classical nova models.
Her X-1 is an accreting neutron star in an intermediate-mass X-ray binary. Like low-mass X-ray binaries (LMXBs), it accretes via Roche-lobe overflow, but similar to many high-mass X-ray binaries containing a neutron star, Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery of radio emission from Her X-1 with the Very Large Array. During the radio observation, the central X-ray source was partially obscured by a warped disk. We measure a radio flux density of $38.7 \pm 4.8$ $\mu$Jy at $9$ GHz but can not constrain the spectral shape. We discuss possible origins of the radio emission, and conclude that coherent emission, a stellar wind, shocks and a propeller outflow are all unlikely explanations. A jet, as seen in LMXBs, is consistent with the observed radio properties. We consider the implications of the presence of a jet in Her X-1 on jet formation mechanisms and on the launcing of jets by neutron stars with strong magnetic fields.
We construct a minimal robust controlled-NOT gate with an Ising-type interaction by which elementary two-qubit gates are implemented. It is robust against inaccuracy of the coupling strength and the obtained quantum circuits are constructed with the minimal number (N=3) of elementary two-qubit gates and several one-qubit gates. It is noteworthy that all the robust circuits can be mapped to one-qubit circuits robust against a pulse length error. We also prove that a minimal robust SWAP gate cannot be constructed with N=3, but requires N=6 elementary two-qubit gates.
We present numerical evidence supporting the validity of the Gallavotti-Cohen Fluctuation Theorem applied to the driven Lorentz gas with Nos\'e-Hoover thermostating. It is moreover argued that the asymptotic form of the fluctuation formula is independent of the amplitude of the driving force, in the limit where it is small.
Let $k$ be a cubic field. We give an explicit formula for the Dirichlet series $\sum_K|\Disc(K)|^{-s}$, where the sum is over isomorphism classes of all quartic fields whose cubic resolvent field is isomorphic to $k$. Our work is a sequel to an unpublished preprint of Cohen, Diaz y Diaz, and Olivier, and we include complete proofs of their results so as not to rely on unpublished work.   This is a companion to a previous paper where we compute the Dirichlet series associated to cubic fields having a given quadratic resolvent.
Diffuse X-ray emission from the Magellanic Clouds (MCs) is studied by using all the archival data of pointed ROSAT Position Sensitive Proportional Counter (PSPC) observations. For this purpose, contributions from the point and point-like sources in the ROSAT High Resolution Imager (HRI) and PSPC source catalogues are eliminated and periods of high solar activity are excluded. The spectral analysis yielded characteristic temperatures of 10^6 - 10^7 K for the hot thin plasma of the ISM which extends over the whole Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). The total unabsorbed luminosity in the 0.1 - 2.4 keV band within the observed area amounts to 3.2 x 10^38 erg s^-1 in the LMC and 1.1 x 10^37 erg s^-1 in the SMC, each with an uncertainty of -40%, +100%. The X-ray luminosity of the LMC is comparable to that of other nearby galaxies with pronounced star formation. In the LMC, hot regions were found especially around the supergiant shell (SGS) LMC 4 and in the field covering SGS LMC 2 and LMC 3. Highest temperatures for the SMC were derived in the southwestern part of the galaxy. The diffuse X-ray emission is most likely a superposition of the emission from the hot gas in the interior of shells and supershells as well as from the halo of these galaxies.
We examine time reversal invariance in the beta-decays of 8B(2+) and 8Li(2+) to 8Be(2+) in detail, with particular attention to final state interactions of the two alpha particles from the decay of 8Be, and of the electron (positron) with the daughter nucleus. A R-matrix formulation is used, with the initial state described by a shell model. The R-matrix parameters are obtained by fitting the alpha-\alpha scattering phase shifts and allowed beta-decay rates. Because the nuclear final state interaction effects on the time reversal test come from second forbidden beta-decays, they are small and can be minimized by a suitable choice of kinematic conditions. The e(+/-)-nucleus Coulomb interaction induced T-violation effects depend on the first forbidden operators.
We use the resonances of the spherical shell potential to present a thorough description of the Gamow (quasinormal) states within the rigged Hilbert space. It will be concluded that the natural setting for the Gamow states is a rigged Hilbert space whose test functions fall off at infinity faster than Gaussians.
We study the Fisher-KPP equation where the Laplacian is replaced by the generator of a Feller semigroup with power decaying kernel, an important example being the fractional Laplacian. In contrast with the case of the stan- dard Laplacian where the stable state invades the unstable one at constant speed, we prove that with fractional diffusion, generated for instance by a stable L\'evy process, the front position is exponential in time. Our results provide a mathe- matically rigorous justification of numerous heuristics about this model.
The long-term optical, X-ray and $\gamma$-ray data of blazar 3C 279 have been compiled from $Swift$-XRT, $RXTE$ PCA, $Fermi$-LAT, SMARTS and literature. The source exhibits strong variability on long time scales. Since 1980s to now, the optical $R$ band light curve spans above 32 yr, and a possible 5.6-yr-long quasi-periodic variation component has been found in it. The optical spectral behavior has been investigated. In the optical band, the mean spectral index is -1.71. The source exhibits an obvious special spectral behavior. In the low state, the source shows a clear bluer-when-brighter behavior in a sense that the optical spectrum turns harder (flatter) when the brightness increases. While in the high state, the optical spectrum is stable, that means the source spectral index does not vary with the brightness. The correlation analysis has been performed among optical, X-ray and $\gamma$-ray energy bands. The result indicates that the variations of $\gamma$-ray and X-ray bands are well correlated without time delay on the time scale of days, and their variations exhibit weak correlations with those of optical band. The variations, especial outbursts, are simultaneous, but the magnitude of variations is disproportionate. The detailed analysis reveals that the main outbursts exhibit strong correlations in different $\gamma$-ray, X-ray and optical bands.
We prove the scattering for the defocusing generalized Benjamin-Ono equation in the energy space $H^{\frac{1}{2}}(\mathbb{R})$. We first establish the monotonicity formula that describes the unidirectional propagation. More precisely, it says that the center of energy moves faster than the center of mass. This type of monotonicity was first observed by Tao (DCDS 2007) in the defocusing gKdV equations.   We use the monotonicity in the setting of compactness-contradiction argument to prove the large data scattering in the energy space $H^{\frac{1}{2}}(\mathbb{R})$. On the way, we extend critical local theory of Vento (IMRN 2010) to the subcritical regime. Indeed, we obtain subcritical local theory and global well-posedness in the energy space.
In this article, we classify the characters associated to algebraic points on Shimura curves of $\Gamma_0(p)$-type, and over a quadratic field we show that there are at most elliptic points on such a Shimura curve for every sufficiently large prime number $p$. This is an analogue of the study of rational points or points over a quadratic field on the modular curve $X_0(p)$ by Mazur and one of the author (Momose). We also apply the result to a finiteness conjecture on abelian varieties with constrained prime power torsion by Rasmussen-Tamagawa.
In this paper, we obtain a Schwartz-Zippel type estimate for homogenous finite field polynomials. Specifically, we use a probabilistic recursion technique to find upper and lower bounds for the number of zeros of a homogenous polynomial and illustrate our result with two examples involving perfect matching in bipartite graphs and common zeros in a collection of polynomials, respectively.
In this paper, we explore the task of generating photo-realistic face images from hand-drawn sketches. Existing image-to-image translation methods require a large-scale dataset of paired sketches and images for supervision. They typically utilize synthesized edge maps of face images as training data. However, these synthesized edge maps strictly align with the edges of the corresponding face images, which limit their generalization ability to real hand-drawn sketches with vast stroke diversity. To address this problem, we propose DeepFacePencil, an effective tool that is able to generate photo-realistic face images from hand-drawn sketches, based on a novel dual generator image translation network during training. A novel spatial attention pooling (SAP) is designed to adaptively handle stroke distortions which are spatially varying to support various stroke styles and different levels of details. We conduct extensive experiments and the results demonstrate the superiority of our model over existing methods on both image quality and model generalization to hand-drawn sketches.
Using observations by the Solar Dynamics Observatory from June 2010 to December 2017, we have performed the first statistical investigation of circular-ribbon flares (CFs) and examined the white-light emission in these CFs. We find 90 CFs occurring in 36 active regions (ARs), including 8 X-class, 34 M-class, 48 C- and B-class flares. The occurrence rate of white-light flares (WLFs) is 100\% (8/8) for X-class CFs, $\sim$62\% (21/34) for M-class CFs, and $\sim$8\% (4/48) for C- and B-class CFs. Sometimes we observe several CFs in a single AR, and nearly all of them are WLFs. Compared to normal CFs, CFs with white-light enhancement tend to have a shorter duration, smaller size, stronger electric current and more complicated magnetic field. We find that for X-class WLFs, the white-light enhancement is positively correlated with the flare class, implying that the white-light enhancement is largely determined by the amount of released energy. However, there is no such correlation for M- and C-class WLFs, suggesting that other factors such as the time scale, spatial scale and magnetic field complexity may play important roles in the generation of white-light emission if the released energy is not high enough.
NGC 6791 is a unique stellar system among Galactic open clusters being at the same time one of the oldest open clusters and the most metal rich. Combination of its properties is puzzling and poses question of its origin. One possible scenario is that the cluster formed close to the Galactic Center and later migrated outwards to its current location. In this work we study the cluster's orbit and investigate the possible migration processes which might have displaced NGC 6791 to its present-day position, under the assumption that it actually formed in the inner disk. To this aim we performed integrations of NGC 6791's orbit in a potential consistent with the main Milky Way parameters. In addition to analytical expressions for halo, bulge and disk, we also consider the effect of bar and spiral arm perturbations, which are expected to be very important for the disk dynamical evolution, especially inside the solar circle. Starting from state-of-the art initial conditions for NGC 6791, we calculate 1000 orbits back in time for about 1 Gyr turning on and off different non-axisymmetric components of the global potential. We then compare statistical estimates of the cluster's recent orbital parameters with the orbital parameters of 10^4 test-particles originating close to the Galactic Center (having initial galocentric radii in the range of 3-5 kpc) and undergoing radial migration during 8 Gyr of forward integration. We find that a model which incorporates a strong bar and spiral arm perturbations can indeed be responsible for the migration of NGC 6791 from the inner disk (galocentric radii of 3-5 kpc) to its present-day location. Such a model can provide orbital parameters which are close enough to the observed ones. However, the probability of this scenario as it results from our investigations is very low.
We report the detection, for the first time in space, of cyano thioformaldehyde (HCSCN) and propynethial (HCSCCH) towards the starless core TMC-1. Cyano thioformaldehyde presents a series of prominent a- and b-type lines, which are the strongest previously unassigned features in our Q-band line survey of TMC-1. Remarkably, HCSCN is four times more abundant than cyano formaldehyde (HCOCN). On the other hand, HCSCCH is five times less abundant than propynal (HCOCCH). Surprisingly, we find an abundance ratio HCSCCH/HCSCN of 0.25, in contrast with most other ethynyl-cyanide pairs of molecules for which the CCH-bearing species is more abundant than the CN-bearing one. We discuss the formation of these molecules in terms of neutral-neutral reactions of S atoms with CH2CCH and CH2CN radicals as well as of CCH and CN radicals with H2CS. The calculated abundances for the sulphur-bearing species are, however, significantly below the observed values, which points to an underestimation of the abundance of atomic sulphur in the model or to missing formation reactions, such as ion-neutral reactions.
Long-range contextual information is crucial for the semantic segmentation of High-Resolution (HR) Remote Sensing Images (RSIs). However, image cropping operations, commonly used for training neural networks, limit the perception of long-range contexts in large RSIs. To overcome this limitation, we propose a Wide-Context Network (WiCoNet) for the semantic segmentation of HR RSIs. Apart from extracting local features with a conventional CNN, the WiCoNet has an extra context branch to aggregate information from a larger image area. Moreover, we introduce a Context Transformer to embed contextual information from the context branch and selectively project it onto the local features. The Context Transformer extends the Vision Transformer, an emerging kind of neural network, to model the dual-branch semantic correlations. It overcomes the locality limitation of CNNs and enables the WiCoNet to see the bigger picture before segmenting the land-cover/land-use (LCLU) classes. Ablation studies and comparative experiments conducted on several benchmark datasets demonstrate the effectiveness of the proposed method. In addition, we present a new Beijing Land-Use (BLU) dataset. This is a large-scale HR satellite dataset with high-quality and fine-grained reference labels, which can facilitate future studies in this field.
We propose a robust numerical method to find the coefficient of the creation or depletion term of parabolic equations from the measurement of the lateral Cauchy information of their solutions. Most papers in the field study this nonlinear and severely ill-posed problem using optimal control. The main drawback of this widely used approach is the need of some advanced knowledge of the true solution. In this paper, we propose a new method that opens a door to solve nonlinear inverse problems for parabolic equations without any initial guess of the true coefficient. This claim is confirmed numerically. The key point of the method is to derive a system of nonlinear elliptic equations for the Fourier coefficients of the solution to the governing equation with respect to a special basis of L^2. We then solve this system by a predictor-corrector process, in which our computation to obtain the first and second predictors is effective. The desired solution to the inverse problem under consideration follows.