ShantanuT01/DACTYL-Pretraining huggingface dataset:
This paper presents Video K-Net, a simple, strong, and unified framework for fully end-to-end video panoptic segmentation. The method is built upon K-Net, a method that unifies image segmentation via a group of learnable kernels. We observe that these learnable kernels from K-Net, which encode object appearances and contexts, can naturally associate identical instances across video frames. Motivated by this observation, Video K-Net learns to simultaneously segment and track "things" and "stuff" in a video with simple kernel-based appearance modeling and cross-temporal kernel interaction. Despite the simplicity, it achieves state-of-the-art video panoptic segmentation results on Citscapes-VPS, KITTI-STEP, and VIPSeg without bells and whistles. In particular, on KITTI-STEP, the simple method can boost almost 12\% relative improvements over previous methods. On VIPSeg, Video K-Net boosts almost 15\% relative improvements and results in 39.8 % VPQ. We also validate its generalization on video semantic segmentation, where we boost various baselines by 2\% on the VSPW dataset. Moreover, we extend K-Net into clip-level video framework for video instance segmentation, where we obtain 40.5% mAP for ResNet50 backbone and 54.1% mAP for Swin-base on YouTube-2019 validation set. We hope this simple, yet effective method can serve as a new, flexible baseline in unified video segmentation design. Both code and models are released at https://github.com/lxtGH/Video-K-Net.
We study field theories in two spacetime dimensions invariant under a chiral scaling symmetry that acts only on right-movers. The local symmetries include one copy of the Virasoro algebra and a U(1) current algebra. This differs from the 2d conformal group, but in some respects is equally powerful in constraining the theory. In particular, the symmetries on a torus lead to modular covariance of the partition function, which is used to derive a universal formula for the asymptotic density of states. For an application we turn to the holographic description of black holes in quantum gravity, motivated by the fact that the symmetries in the near horizon geometry of any extremal black hole are identical to those of a 2d field theory with chiral scaling. We consider two examples: black holes in warped AdS_3 in topologically massive gravity, and in string theory. In both cases, the density of states in the 2d field theory reproduces the Bekenstein-Hawking entropy of black holes in the gravity theory.
Thanks to extensive observations with X-ray missions and facilities working in other wavelengths, as well as rapidly--advancing numerical simulations of accretion flows, our knowledge of astrophysical black holes has been remarkably enriched. Rapid progress has opened new areas of enquiry, including measurements of black hole spin, the properties and driving mechanisms of jets and disk winds, the impact of feedback into local environments, the origin of periodic and aperiodic X-ray variations, and the nature of super-Eddington accretion flows, among others. The goal of this White Paper is to illustrate how ASTRO-H can make dramatic progress in the study of astrophysical black holes, particularly the study of black hole X-ray binaries.
Deep rest-optical observations are required to accurately constrain the stellar populations of $z\sim8$ galaxies. Due to significant limitations in the availability of such data for statistically complete samples, observational results have been limited to modest numbers of bright or lensed sources. To revolutionize the present characterization of $z\sim8$ galaxies, we exploit the ultradeep ($\sim27$ mag, $3\sigma$) Spitzer/IRAC $3.6\mu$m and $4.5\mu$m data, probing the rest-frame optical at $z\sim8$, over $\sim200$ arcmin$^2$ of the GOODS fields from the recently completed GOODS Re-ionization Era wide-Area Treasury from Spitzer (GREATS) program, combined with observations in the CANDELS UDS and COSMOS fields. We stacked $\gtrsim100$ $z\sim8$ Lyman-Break galaxies in four bins of UV luminosity ($M_\mathrm{UV}\sim -20.7$ to $-18.4$) and study their $H_\mathrm{160}-[3.6]$ and $[3.6]-[4.5]$ colors. We find young ages ($\lesssim100$ Myr) for the three faintest stacks, inferred from their blue $H_\mathrm{160}-[3.6]\sim 0$ mag colors, consistent with a negative Balmer break. Meanwhile, the redder $H_\mathrm{160}-[3.6]$ color seen in the brightest stack is suggestive of slightly older ages. We explored the existence of a correlation between the UV luminosity and age, and find either no trend or fainter galaxies being younger. The stacked SEDs also exhibit very red $[3.6]-[4.5]\sim0.5$ mag colors, indicative of intense [OIII]+H$\beta$ nebular emission and SFR. The correspondingly high specific star-formation rates, sSFR$\gtrsim10$Gyr$^{-1}$, are consistent with recent determinations at similar redshifts and higher luminosities, and support the co-evolution between the sSFR and the specific halo mass accretion rate.
We present a detailed clustering analysis of the young stellar population across the star-forming ring galaxy NGC 6503, based on the deep HST photometry obtained with the Legacy ExtraGalactic UV Survey (LEGUS). We apply a contour-based map analysis technique and identify in the stellar surface density map 244 distinct star-forming structures at various levels of significance. These stellar complexes are found to be organized in a hierarchical fashion with 95% being members of three dominant super-structures located along the star-forming ring. The size distribution of the identified structures and the correlation between their radii and numbers of stellar members show power-law behaviors, as expected from scale-free processes. The self-similar distribution of young stars is further quantified from their autocorrelation function, with a fractal dimension of ~1.7 for length-scales between ~20 pc and 2.5 kpc. The young stellar radial distribution sets the extent of the star-forming ring at radial distances between 1 and 2.5 kpc. About 60% of the young stars belong to the detected stellar structures, while the remaining stars are distributed among the complexes, still inside the ring of the galaxy. The analysis of the time-dependent clustering of young populations shows a significant change from a more clustered to a more distributed behavior in a time-scale of ~60 Myr. The observed hierarchy in stellar clustering is consistent with star formation being regulated by turbulence across the ring. The rotational velocity difference between the edges of the ring suggests shear as the driving mechanism for this process. Our findings reveal the interesting case of an inner ring forming stars in a hierarchical fashion.
In this work, we study the validity of Entropy inequalities under decorrelation assumptions at large-scales, and also we study the problem of Weighted Meyers estimate in perforated domains. As a consequence, we obtain the hypercontractivity of correctors with Neumann boundary conditions.
Person re-identification becomes a more and more important task due to its wide applications. In practice, person re-identification still remains challenging due to the variation of person pose, different lighting, occlusion, misalignment, background clutter, etc. In this paper, we propose a multi-scale body-part mask guided attention network (MMGA), which jointly learns whole-body and part body attention to help extract global and local features simultaneously. In MMGA, body-part masks are used to guide the training of corresponding attention. Experiments show that our proposed method can reduce the negative influence of variation of person pose, misalignment and background clutter. Our method achieves rank-1/mAP of 95.0%/87.2% on the Market1501 dataset, 89.5%/78.1% on the DukeMTMC-reID dataset, outperforming current state-of-the-art methods.
In this paper we derive time reversal imaging functionals for two strongly causal acoustic attenuation models, which have been proposed recently. The time reversal techniques are based on recently proposed ideas of Ammari et al for the thermo-viscous wave equation. Here and there an asymptotic analysis provides reconstruction functionals from first order corrections for the attenuating effect. In addition, we present a novel approach for higher order corrections.
A new solution of the Einstein-Born-Infeld theory in 2+1 space-time is derived. A new solution has no horizon there are two singularity. This space-time has two singular points, however, one of the point at the origin is not in the physical region. We also investigate the energycondition. Then, weak energy condition is satisfied. However, causal energy condition is violated.
This paper proves a Krylov-Safonov estimate for a multidimensional diffusion process whose diffusion coefficients are degenerate on the boundary. As applications the existence and uniqueness of invariant probability measures for the process and Hoelder estimates for the associated partial differential equation are obtained.
In this overview we discuss some recent results of non--uniqueness for the isentropic Euler equations of gas dynamics with particular attention to the role of some admissibility criteria proposed in the literature.
We study all possible sources of inaccuracy in theoretical values of the photometric observables, i.e. amplitude ratios and phase differences, of early B-type main sequence pulsators. Here, we discuss effects of parameters coming from both models of stellar atmospheres and linear nonadiabatic theory of stellar pulsation. In particular, we evaluate for the first time the effect of the departure from the LTE approximation. The atmospheric input comes from line-blanketed, LTE and NLTE plane-parallel, hydrostatic models. To compute the limb-darkening coefficients for NLTE models, we use the Least-Square Method taking into account the accuracy of the flux conservation. We present effects of NLTE atmospheres, chemical composition and opacities on theoretical values of the photometric observables of early B-type pulsators. To this end, we compute tables with the passband fluxes, flux derivatives over effective temperature and gravity as well as the non-linear limb-darkening coefficients in 12 most often used passbands, i.e. in the Str\"omgern system, $uvby$, and in the Johnson-Cousins-Glass system, $UBVRIJHK$. We make these tables public available at the Wroc{\l}aw HELAS Web page, http://helas.astro.uni.wroc.pl.
Using a sample of approximately 14,000 z>2.1 quasars observed in the first year of the Baryon Oscillation Spectroscopic Survey (BOSS), we measure the three-dimensional correlation function of absorption in the Lyman-alpha forest. The angle-averaged correlation function of transmitted flux (F = exp(-tau)) is securely detected out to comoving separations of 60 Mpc/h, the first detection of flux correlations across widely separated sightlines. A quadrupole distortion of the redshift-space correlation function by peculiar velocities, the signature of the gravitational instability origin of structure in the Lyman-alpha forest, is also detected at high significance. We obtain a good fit to the data assuming linear theory redshift-space distortion and linear bias of the transmitted flux, relative to the matter fluctuations of a standard LCDM cosmological model (inflationary cold dark matter with a cosmological constant). At 95% confidence, we find a linear bias parameter 0.16<b<0.24 and redshift-distortion parameter 0.44<beta<1.20, at central redshift z=2.25, with a well constrained combination b(1+\beta)=0.336 +/- 0.012. The errors on beta are asymmetric, with beta=0 excluded at over 5 sigma confidence level. The value of beta is somewhat low compared to theoretical predictions, and our tests on synthetic data suggest that it is depressed (relative to expectations for the Lyman-alpha forest alone) by the presence of high column density systems and metal line absorption. These results set the stage for cosmological parameter determinations from three-dimensional structure in the Lyman-alpha forest, including anticipated constraints on dark energy from baryon acoustic oscillations.
Previous video-based human pose estimation methods have shown promising results by leveraging aggregated features of consecutive frames. However, most approaches compromise accuracy to mitigate jitter or do not sufficiently comprehend the temporal aspects of human motion. Furthermore, occlusion increases uncertainty between consecutive frames, which results in unsmooth results. To address these issues, we design an architecture that exploits the keypoint kinematic features with the following components. First, we effectively capture the temporal features by leveraging individual keypoint's velocity and acceleration. Second, the proposed hierarchical transformer encoder aggregates spatio-temporal dependencies and refines the 2D or 3D input pose estimated from existing estimators. Finally, we provide an online cross-supervision between the refined input pose generated from the encoder and the final pose from our decoder to enable joint optimization. We demonstrate comprehensive results and validate the effectiveness of our model in various tasks: 2D pose estimation, 3D pose estimation, body mesh recovery, and sparsely annotated multi-human pose estimation. Our code is available at https://github.com/KyungMinJin/HANet.
In this work, we prove global existence of solutions for second order differential problems in a general framework. More precisely, we consider second order differential inclusions involving proximal normal cone to a set-valued map. This set-valued map is supposed to take admissible values (so in particular uniformly prox-regular values, which may be non-smooth and non-convex). Moreover we require the solution to satisfy an impact law, appearing in the description of mechanical systems with inelastic shocks.
We present the final nine-year maps and basic results from the WMAP mission. We provide new nine-year full sky temperature maps that were processed to reduce the asymmetry of the effective beams. Temperature and polarization sky maps are examined to separate CMB anisotropy from foreground emission, and both types of signals are analyzed in detail. The WMAP mission has resulted in a highly constrained LCDM cosmological model with precise and accurate parameters in agreement with a host of other cosmological measurements. When WMAP data are combined with finer scale CMB, baryon acoustic oscillation, and Hubble constant measurements, we find that Big Bang nucleosynthesis is well supported and there is no compelling evidence for a non-standard number of neutrino species (3.84+/-0.40). The model fit also implies that the age of the universe is 13.772+/-0.059 Gyr, and the fit Hubble constant is H0 = 69.32+/-0.80 km/s/Mpc. Inflation is also supported: the fluctuations are adiabatic, with Gaussian random phases; the detection of a deviation of the scalar spectral index from unity reported earlier by WMAP now has high statistical significance (n_s = 0.9608+/-0.0080); and the universe is close to flat/Euclidean, Omega_k = -0.0027 (+0.0039/-0.0038). Overall, the WMAP mission has resulted in a reduction of the cosmological parameter volume by a factor of 68,000 for the standard six-parameter LCDM model, based on CMB data alone. For a model including tensors, the allowed seven-parameter volume has been reduced by a factor 117,000. Other cosmological observations are in accord with the CMB predictions, and the combined data reduces the cosmological parameter volume even further. With no significant anomalies and an adequate goodness-of-fit, the inflationary flat LCDM model and its precise and accurate parameters rooted in WMAP data stands as the standard model of cosmology.
We propose a novel deep-learning-based system for vessel segmentation. Existing methods using CNNs have mostly relied on local appearances learned on the regular image grid, without considering the graphical structure of vessel shape. To address this, we incorporate a graph convolutional network into a unified CNN architecture, where the final segmentation is inferred by combining the different types of features. The proposed method can be applied to expand any type of CNN-based vessel segmentation method to enhance the performance. Experiments show that the proposed method outperforms the current state-of-the-art methods on two retinal image datasets as well as a coronary artery X-ray angiography dataset.
Strong-coupling expansion is performed for the lattice phi^4 model in 1+1 dimensions. Because the strong-coupling limit itself is not solvable, we employed numerical calculations so as to set up unperturbed eigensystems. Restricting the number of Hilbert-space bases, we performed linked-cluster expansion up to eleventh order. We carried out alternative simulation by means of the density-matrix renormalization group. Thereby, we confirmed that our series-expansion data with a convergence-acceleration trick are in good agreement with the simulation result. Through the analytic continuation to the domain of negative biquadratic interaction, we obtain the false-vacuum decay rate. Contrary to common belief that tunnelling phenomenon lies out of perturbative treatments, our series expansion reproduces the instanton-theory behaviour for high potential barrier. For shallow barrier, on the contrary, our result tells that the relaxation is no more described by instanton, but the decay rate acquires notable enhancement.
In this work we study constant-coefficient first order systems of partial differential equations and give necessary and sufficient conditions for those systems to have a well posed Cauchy Problem. In many physical applications, due to the presence of constraints, the number of equations in the PDE system is larger than the number of unknowns, thus the standard Kreiss conditions can not be directly applied to check whether the system admits a well posed initial value formulation. In this work we find necessary and sufficient conditions such that there exists a reduced set of equations, of the same dimensionality as the set of unknowns, which satisfy Kreiss conditions and so are well defined and properly behaved evolution equations. We do that by studying the systems using the Kronecker decomposition of matrix pencils and, once the conditions are meet, finding specific families of reductions which render the system strongly hyperbolic. We show the power of the theory in some examples: Klein Gordon, the ADM, and the BSSN equations by writing them as first order systems, and studying their Kronecker decomposition and general reductions.
In this paper, we present an approach to the fractional Dunkl Laplacian in a framework emerging from certain reflection symmetries in Euclidean spaces. Our main result is pointwise formulas, Bochner subordination, and an extension problem for the fractional Dunkl Laplacian as well
An effective Lagrangian approach based on an extended Einstein-Aether (EA) model is presented and formulated in a generic non flat Fridman-Lemaitre-Robertson-Walker (FLRW) space-time. For a flat FLRW space-time, a Friedmann equation similar to the one obtained in Quantum Loop Cosmology (QLC) is reproduced, with related non singular bounce solution. Finally, the Static Spherically Symmetric (SSS) solutions are investigated.
A system of equal mixture of $^6Li$ atomic Fermi gas of two hyperfine states loaded into a cubic three-dimensional optical lattice is studied assuming a negative scattering length (BCS side of the Feshbach resonance). When the interaction is attractive, fermionic atoms can pair and form a superfluid. The dispersion of the phonon-like mode and the speed of sound in the long-wavelength limit are obtained by solving the Bethe-Salpeter equations for the collective modes of the attractive Hubbard Hamiltonian.
A first-principles study of the structural and electronic properies of carbon impurities in CuIn$_{1-x}$Ga$_x$Se$_{2}$ is presented. Carbon is present in organic molecules in the precursor solutions used in nonvacuum growth methods, making more efficient use of material, time and energy than traditional vacuum methods. The formation energies of several carbon impurities are calculated using the hybrid HSE06 functional. C$_{\mathrm{Cu}}$ acts as a shallow donor, C$_{\mathrm{In}}$ and interstitial C yield deep donor levels in CuInSe$_{2}$, while in CuGaSe$_{2}$ C$_{\mathrm{Ga}}$ and interstitial C act as deep amphoteric defects. So, if present, these defects reduce the majority carrier (hole) concentration by compensating the acceptor levels and become trap states for the photogenerated minority carriers (electrons). However, the formation energies of the calculated carbon impurities are high, even under C-rich growth conditions. Therefore, these impurities are not likely to form and will probably be expelled to the intergranular region and out of the absorber layer.
NASA's NICER telescope has recently provided evidence for non-dipolar magnetic field structures in rotation-powered millisecond pulsars. These stars are assumed to have gone through a prolonged accretion spin-up phase, begging the question of what accretion flows onto stars with complex magnetic fields would look like. We present results from a suite of GRMHD simulations of accreting neutron stars for dipole, quadrupole, and quadrudipolar stellar field geometries. This is a first step towards simulating realistic hotspot shapes in a general relativistic framework to understand hotspot variability in accreting millisecond pulsars. We find that the location and size of the accretion columns resulting in hotspots changes significantly depending on initial stellar field strength and geometry. We also find that the strongest contributions to the stellar torque are from disk-connected fieldlines and the pulsar wind, leading to spin-down in almost all of the parameter regime explored here. We further analyze angular momentum transport in the accretion disk due to large scale magnetic stresses, turbulent stresses, wind- and compressible effects which we identify with convective motions. The disk collimates the initial open stellar flux forming jets. For dipoles, the disk-magnetosphere interaction can either enhance or reduce jet power compared to the isolated case. However for quadrupoles, the disk always leads to an enhanced net open flux making the jet power comparable to the dipolar case. We discuss our results in the context of observed neutron star jets and provide a viable mechanism to explain radio power both in the low- and high-magnetic field case.
We present a convariant formulation for radiative transfer in curved space time and demonstrate some applications in the black-hole systems. We calculate the emission from semi-transparent accretion tori around black holes, for opacity provided by the Fe K lines and for opacity dominated by electron scattering. We also calculate the emission from radiative inefficient accretion flow in black holes with opacity provided by electron-positron annihilation lines. Finally we show shadows cast by accreting black holes with different spins and with different distribution of warm material around them.
The Solar Simulations for the Atacama Large Millimeter Observatory Network (SSALMON) was initiated in 2014 in connection with two ALMA development studies. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful new tool, which can also observe the Sun at high spatial, temporal, and spectral resolution. The international SSALMONetwork aims at coordinating the further development of solar observing modes for ALMA and at promoting scientific opportunities for solar physics with particular focus on numerical simulations, which can provide important constraints for the observing modes and can aid the interpretation of future observations. The radiation detected by ALMA originates mostly in the solar chromosphere - a complex and dynamic layer between the photosphere and corona, which plays an important role in the transport of energy and matter and the heating of the outer layers of the solar atmosphere. Potential targets include active regions, prominences, quiet Sun regions, flares. Here, we give a brief overview over the network and potential science cases for future solar observations with ALMA.