ShantanuT01/DACTYL-Pretraining huggingface dataset:
Blind video decaptioning is a problem of automatically removing text overlays and inpainting the occluded parts in videos without any input masks. While recent deep learning based inpainting methods deal with a single image and mostly assume that the positions of the corrupted pixels are known, we aim at automatic text removal in video sequences without mask information. In this paper, we propose a simple yet effective framework for fast blind video decaptioning. We construct an encoder-decoder model, where the encoder takes multiple source frames that can provide visible pixels revealed from the scene dynamics. These hints are aggregated and fed into the decoder. We apply a residual connection from the input frame to the decoder output to enforce our network to focus on the corrupted regions only. Our proposed model was ranked in the first place in the ECCV Chalearn 2018 LAP Inpainting Competition Track2: Video decaptioning. In addition, we further improve this strong model by applying a recurrent feedback. The recurrent feedback not only enforces temporal coherence but also provides strong clues on where the corrupted pixels are. Both qualitative and quantitative experiments demonstrate that our full model produces accurate and temporally consistent video results in real time (50+ fps).
The nucleosynthesis in the first massive stars may be constrained by observing the surface composition of long-lived very iron-poor stars born around 10 billion years ago from material enriched by their ejecta. Many interesting clues on physical processes having occurred in the first stars can be obtained just based on nuclear aspects. Two facts are particularly clear, 1) in these first massive stars, mixing must have occurred between the H-burning and the He-burning zone during their nuclear lifetimes; 2) only the outer layers of these massive stars have enriched the material from which the very iron-poor stars, observed today in the halo, have formed. These two basic requirements can be obtained by rotating stellar models at very low metallicity. In the present paper, we discuss the arguments supporting this view and illustrates the sensitivity of the results concerning the [Mg/Al] ratio on the rate of the reaction Na(23)(p,\gamma)Mg(24).
We consider Quarkyonic Matter to naturally explain the observed properties of neutron stars. We argue that such matter might exist at densities close to that of nuclear matter and at the onset, the pressure and the sound velocity in Quarkyonic matter increase rapidly. In the limit of large number of quark colors $N_c$, this transition is characterized by a discontinuous change in pressure as a function of baryon number density. We make a simple model of Quarkyonic matter and show that generically the sound velocity is a non-monotonic function of density -- it reaches a maximum at relatively low density, decreases, and then increases again to its asymptotic value of $1/\sqrt{3}$.
The X(3872) and Y(4260), among a host of charmonium-like mesons, have rather unusual properties: the former has very small total width, the latter has large rate into $\pi^+\pi^-J/\psi$ channel. It would not be easy to settle between the many suggested explanations for their composition. We point out that discovering the bottom counterparts should shed much light on the issue. The narrow state can be searched for at the Tevatron via $p\bar p \to \pi^+\pi^-\Upsilon + X$, but the LHC should be much more promising. The state with large overlap with $\Upsilon$ can be searched for at B factories via radiative return $e^+e^- \to \gamma_{\rm ISR} + \pi^+\pi^-\Upsilon$ on $\Upsilon(5S)$, or by $e^+e^- \to \pi^+\pi^-\Upsilon$ direct scan.
We elucidate the origin and nature of the D'yakonov-Perel' spin relaxation in a quantum wire structure, showing (analytically) that there are three necessary conditions for it to exist: (i) transport must be multi-channeled, (ii) there must be a Rashba spin orbit interaction in the wire, and (iii) there must also be a Dresselhaus spin orbit interaction. Therefore, the only effective way to completely eliminate the D'yakonov-Perel' relaxation in compound semiconductor channels with structural and bulk inversion asymmetry is to ensure strictly single channeled transport. In view of that, recent proposals in the literature that advocate using multi-channeled quantum wires for spin transistors appear ill-advised.
A power counting rule is provided that allows us to obtain upper bounds for the absolute values of Feynman parametric integrands. The rule reflects both the ultraviolet and infrared behavior taking into account that the external momenta are on the mass shell. It gives us the ability to rigorously prove the absolute convergence of the corresponding integrals. The consideration is limited to the case of the quantum electrodynamics Feynman graphs contributing to the lepton magnetic moments and not containing either lepton loops or ultraviolet divergent subgraphs. However, a rigorous mathematical proof is given for all Feynman graphs satisfying these restrictions. The power counting rule is formulated in terms of Hepp's sectors, ultraviolet degrees of divergence and so-called I-closures. The obtained upper bound can not be substantially improved: the illustrative example is provided. The paper provides the first mathematically rigorous treatment of the ultraviolet behavior together with the on-shell infrared behavior with some kind of generality. Practical applications of this rule are explained.
We theoretically investigate the motional excitation of a single ion caused by spring-constant and position uctuations of a harmonic trap during trap shuttling processes. A detailed study of the sensitivity on noise for several transport protocols and noise spectra is provided. The effect of slow spring-constant drifts is also analyzed. Trap trajectories that minimize the excitation are designed combining invariant-based inverse engineering, perturbation theory, and optimal control.
We discuss the impact of the new LHCb fixed-target $p\!+\!^{4}\!He$ data for $D^0/{\bar D}^0$ production on the intrinsic $c \bar c$ component in the nucleon wave function. Within the scenario presented here neither the traditional gluon-gluon fusion or quark-antiquark annihilation mechanisms calculated in the $k_T$-factorization approach nor their counterparts from the collinear next-to-leading order collinear framework are sufficient to describe the transverse momentum and rapidity distributions of $D^0/{\bar D}^0$ mesons. First the $c{\bar c}$-pair production within the standard frameworks is considered. Here a crucial role of the $c \to D$ hadronization effects at low energies and low transverse momenta is found and discussed, which was not analyzed in previous studies. A contribution related to intrinsic $c \bar c$ component in the nucleon wave function is included in addition. Two models of the symmetric ($c(x) = \bar c(x)$) intrinsic charm (IC) component are considered. The intrinsic charm $g^* c \to g c$ (or $g^* {\bar c} \to g {\bar c}$) contribution needs to be regularized in order to obtain a suppression of the minijet $p_{T}$ spectrum present in the phenomenological minijet model, commonly used in Monte Carlo generators. We show that in our model the regularization parameter can be obtained from the fit to the LHCb fixed-target data under consideration here. We discuss uncertainties of our calculations (scale, charm quark mass, fragmentation function) as well as set limits on the IC probability. According to our model the intrinsic charm probability $P_{IC} = 1.65\%$ allows to significantly improve description of the LHCb data but the number is rather uncertain.
We present a model of the analog geometry in a magnetohydrodynamic (MHD) flow. For the MHD flow with magnetic pressure-dominated and gas pressure-dominated conditions, we obtain the magnetoacoustic metric for the fast MHD mode. For the slow MHD mode, on the other hand, the wave is governed by the advective-type equation without an isotropic dispersion term. Thus, the "distance" perpendicular to the wave propagation is not defined and the magnetoacoustic metric cannot be introduced. To investigate the properties of the magnetoacoustic geometry for the fast mode, we prepare a two-dimensional axisymmetric inflow and examine the behavior of magnetoacoustic rays which is a counterpart of the MHD waves in the eikonal limit. We find that the magnetoacoustic geometry is classified into three types depending on two parameters characterizing the background flow:~analog spacetimes of rotating black holes, ultra spinning stars with ergoregions, and spinning stars without ergoregions. We address the effects of the magnetic pressure on the effective geometries.
There is increasing interest in extended source effects in microlensing events, as probes of the unresolved sources. Previous work has either presumed a uniform source, or else required an approximate or numerical treatment of the amplification function averaged over the source disk. In this paper, I present analytic expressions for the angle-averaged amplification functions for the rotationally-symmetric intensity and polarization cases.   These integrals will allow us to use the technology of inverse problems to study the source limb-darkening and limb-polarization functions.
We analyze the symmetries and other invariant qualities of the $\mathcal{D}$-metrics (type D aligned Einstein Maxwell solutions with cosmological constant whose Debever null principal directions determine shear-free geodesic null congruences). We recover some properties and deduce new ones about their isometry group and about their quadratic first integrals of the geodesic equation, and we analyze when these invariant symmetries characterize the family of metrics. We show that the subfamily of the Kerr-NUT solutions are those admitting a Papapetrou field aligned with the Weyl tensor.
The sign of $A_{\rm CP}(K^-\pi^+) < 0$, the evidence for $\bar B^0 \to \pi^0\pi^0$, and the possibly sizable $A_{\pi\pi}$ and $S_{\pi\pi}$ in $\bar B^0 \to \pi^+\pi^-$ all suggest that final state rescattering may be needed in $\bar B\to PP$ decay, which is echoed by large color suppressed $\bar B^0\to D^0h^0$ modes. An SU(3) formalism of ${\bf 8}\otimes {\bf 8} \to {\bf 8}\otimes {\bf 8}$ rescattering in $PP$ final states leads to interesting predictions, in particular allowing for small $\bar B^0 \to K^-K^+$.
A new mathematical framework is formulated to derive the effective equations of motion for the constrained quantum system which possesses an internal clock. In the realm close to classical behavior, the quantum evolution is approximated by a finite system of coupled but ordinary differential equations adhered to the weakly imposed Hamiltonian constraint. For the simplified version of loop quantum cosmology in the Bianchi I model with a free massless scalar filed, the resulting effective equations of motion affirm the bouncing scenario predicted by the previous studies: The big bang singularity is resolved and replaced by the big bounces, which take place up to three times, once in each diagonal direction, whenever the directional density approaches the critical value in the regime of Planckian density. It is also revealed that back-reaction arises from the quantum corrections and modifies the precise value of the directional density at the bouncing epoch. Additionally, as an example of symmetry reduction, we study isotropy emerging from the anisotropic Bianchi I model in the context of effective equations of motion.
The metric underlying the mixed state geometric phase in unitary and nonunitary evolution [Phys. Rev. Lett. {\bf 85}, 2845 (2000); Phys. Rev. Lett. {\bf 93}, 080405 (2004)] is delineated. An explicit form for the line element is derived and shown to be related to an averaged energy dispersion in the case of unitary evolution. The line element is measurable in interferometry involving nearby internal states. Explicit geodesics are found in the single qubit case. It is shown how the Bures line element can be obtained by extending our approach to arbitrary decompositions of density operators. The proposed metric is applied to a generic magnetic system in a thermal state.
Classification theory and the study of projective varieties which are covered by rational curves of minimal degrees naturally leads to the study of families of singular rational curves. Since families of arbitrarily singular curves are hard to handle, it has been shown in a previous paper that there exists a partial resolution of singularities which transforms a bundle of possibly badly singular curves into a bundle of nodal and cuspidal plane cubics.   In cases which are of interest for classification theory, the total spaces of these bundles will clearly be projective. It is, however, generally false that an arbitrary bundle of plane cubics is globally projective. For that reason the question of projectivity seems to be of interest, and the present work gives a characterization of the projective bundles.
A recently developed quark model approach to pseudoscalar meson photoproduction is extended to electroproduction process for the $\eta$ meson in the kinematics of momentum transfer $Q^2 \leq$ 4 (GeV/c)$^2$ and total center of mass energy $W \leq$ 1.6 GeV. Existing data are well reproduced and the roles of the $S_{11}(1535)$ and $D_{13}(1520)$ resonances are closely investigated. In the study of the longitudinal excitation of the $S_{11}(1535)$ resonance, a reliable constraint on the $S_{11}(1535)$ properties is obtained by cleanly removing the electromagnetic transition from the $\gamma_{(v)} p \to S_{11}(1535) \to \eta p$ amplitude. Thus, the fitted quantities can be determined with an uncertainty of about 15%. This could be the first direct constraint on the $S_{11}(1535)$ properties in theory.
The bead process is the particle system defined on parallel lines, with underlying measure giving constant weight to all configurations in which particles on neighbouring lines interlace, and zero weight otherwise. Motivated by the statistical mechanical model of the tiling of an $abc$-hexagon by three species of rhombi, a finitized version of the bead process is defined. The corresponding joint distribution can be realized as an eigenvalue probability density function for a sequence of random matrices. The finitized bead process is determinantal, and we give the correlation kernel in terms of Jacobi polynomials. Two scaling limits are considered: a global limit in which the spacing between lines goes to zero, and a certain bulk scaling limit. In the global limit the shape of the support of the particles is determined, while in the bulk scaling limit the bead process kernel of Boutillier is reclaimed, after approriate identification of the anisotropy parameter therein.
Quantum criticality that goes beyond the Landau framework of order-parameter fluctuations is playing a central role in elucidating the behavior of strange metals. A prominent case appears in Kondo lattice systems, which have been extensively analysed in terms of an effective Bose-Fermi Kondo model. Here, a spin is simultaneously coupled to conduction electron bands and gapless vector bosons that represent magnetic fluctuations. The Bose-Fermi Kondo model features interacting fixed points of Kondo destruction with such properties as dynamical Planckian ($\hbar \omega / k_{\rm B} T$) scaling and loss of quasiparticles. Here we carry out a renormalization-group analysis of the model with spin isotropy and identify pair-wise annihilations of the fixed points as the spectrum of the bosonic bath evolves. Our analysis not only provides an essentially complete understanding of the previous numerical results of an SU(2)-symmetric model, but also reveals a surprising feature of sequential fixed-point annihilation. Our results lay the foundation for the understanding of quantum criticality in spin-isotropic heavy-fermion metals as well as in doped Mott-Hubbard systems.
The importance of including colour octet contributions in describing decay and production of quarkonium states is briefly discussed for two cases : the radiative decays of the $\Upsilon$ and the production of $J/\psi$ in the inclusive $B$ decays. It is shown how information on the non-perturbative matrix elements can be obtained by comparing the theoretical expressions computed at next-to-leading order in $\alpha_s$ with the experimental data.
We consider Bondi's radiating metric in the context of the teleparallel equivalent of general relativity (TEGR). This metric describes the asymptotic form of a radiating solution of Einstein's equations. The total gravitational energy for this solution can be calculated by means of pseudo-tensors in the static case. In the nonstatic case, Bondi defines the {\it mass aspect} $m(u)$, which describes the mass of an isolated system. In this paper we express Bondi's solution in asymptotically spherical 3+1 coordinates, not in radiation coordinates, and obtain Bondi's energy in the static limit by means of the expression for the gravitational energy in the framework of the TEGR. We can either obtain the total energy or the energy inside a large (but finite) portion of the three-dimensional spacelike hypersurface, whose boundary is far away from the source. The relationship of the present energy expression with Moller's energy is established.
Given a 4-regular graph $F$, we introduce a binary matroid $M_{\tau}(F)$ on the set of transitions of $F$. Parametrized versions of the Tutte polynomial of $M_{\tau}(F)$ yield several well-known graph and knot polynomials, including the Martin polynomial, the homflypt polynomial, the Kauffman polynomial and the Bollob\'as-Riordan polynomial.
In this paper we analyse the Gevrey well-posedness of the Cauchy problem for weakly hyperbolic equations of general form with time-dependent coefficients. The results involve the order of lower order terms and the number of multiple roots. We also derive the corresponding well-posedness results in the space of Gevrey Beurling ultradistributions.
{\iota} Ori is a well studied massive binary consisting of an O9 III + B1 III/IV star. Due to its high eccentricity (e = 0.764) and short orbital period (P orb = 29.13376 d), it has been considered to be a good candidate to show evidence of tidal effects; however, none have previously been identified. Using photometry from the BRITE-Constellation space photometry mission we have confirmed the existence of tidal distortions through the presence of a heartbeat signal at periastron. We combine spectroscopic and light curve analyses to measure the masses and radii of the components, revealing {\iota} Ori to be the most massive heartbeat system known to date. In addition, using a thorough frequency analysis, we also report the unprecedented discovery of multiple tidally induced oscillations in an O star. The amplitudes of the pulsations allow us to empirically estimate the tidal circularization rate, yielding an effective tidal quality factor Q $\approx 4 \times 10^{4}$ .
To complement the IceCube neutrino telescope currently under construction at the South Pole, the three Mediterranean neutrino telescope projects ANTARES, NEMO and NESTOR have joined forces to develop, construct and operate a km^3-scale neutrino telescope in the Mediterranean Sea. Since February 2006, the technical specifications and performance of such a detector are studied in the framework of a 3-year EU-funded Design Study. In 2009 a technical design report will be released laying the foundations for the construction of the detector. In the following, the current status of the Design Study is presented and examples of solutions for the technical challenges are discussed.
The chaotic behavior in FRW cosmology with a scalar field is studied for scalar field potentials less steep than quadratic. We describe a transition to much stronger chaos for appropriate parameters of such potentials. The range of parameters which allows this transition is specified. The influence of ordinary matter on the chaotic properties of this model is also discussed.
A k-ary semi-algebraic relation E on R^d is a subset of R^{kd}, the set of k-tuples of points in R^d, which is determined by a finite number of polynomial equations and inequalities in kd real variables. The description complexity of such a relation is at most t if the number of polynomials and their degrees are all bounded by t. A subset A of R^d is called homogeneous if all or none of the k-tuples from A satisfy E. A large number of geometric Ramsey-type problems and results can be formulated as questions about finding large homogeneous subsets of sets in R^d equipped with semi-algebraic relations.   In this paper we study Ramsey numbers for k-ary semi-algebraic relations of bounded complexity and give matching upper and lower bounds, showing that they grow as a tower of height k-1. This improves on a direct application of Ramsey's theorem by one exponential and extends a result of Alon, Pach, Pinchasi, Radoi\v{c}i\'c, and Sharir, who proved this for k=2. We apply our results to obtain new estimates for some geometric Ramsey-type problems relating to order types and one-sided sets of hyperplanes. We also study the off-diagonal case, achieving some partial results.
We study a 1D fluid mechanics model with nonlocal velocity. The equation can be viewed as a fractional porous medium flow, a 1D model of the quasi-geostrophic equation, and also a special case of Euler-Alignment system. For strictly positive smooth initial data, global regularity has been proved by Do, Kiselev, Ryzhik and Tan. We construct a family of non-negative smooth initial data so that solution loses $C^1$ regularity. Our result indicates that strict positivity is a critical condition to ensure global regularity of the system. We also extend our construction to the corresponding models in multi-dimensions.
A combined variable theory of gravity and scalar field is developed under ADM formulation by redefining new canonical conjugate variables ({\Phi}, {\Pi}). It is a dynamical theory of the space-matter with implicit time dependence. Quantizing this new field theory results in quantization of geometry and scalar field combined.
A new approach to effective theory of quarks in the instanton vacuum is presented. Exact equations for the quark propagator and Lagrangian are derived which contain contributions of all quark modes with known coefficients. The resulting effective Lagrangian differs from the standard one and resembles that of the Nambu-Jona-Lasinio model.
Triangular modular curves are a generalization of modular curves that arise from quotients of the upper half-plane by congruence subgroups of hyperbolic triangle groups. These curves also arise naturally as a source of Belyi maps with monodromy $\text{PGL}_2(\mathbb{F}_q)$ or $\text{PSL}_2(\mathbb{F}_q)$. We present a computational approach to enumerate Borel-type triangular modular curves of low genus, and we carry out this enumeration for prime level and small genus.
The quasi two-dimensional magnetic BaNi$_{2}$V$_{2}$O$_{8}$ is studied by using high-resolution thermal expansion in magnetic fields up to 10 T applied along the c-axis. A slight increase of about 1 % of the three-dimensional antiferromagnetic ordering temperature $T_N$ is observed at 10 T. Positive and negative pressure dependencies of $T_N$, respectively, are inferred from the thermal expansion $\alpha(T)$ for pressures applied along the $a$- and $c$-axes.
We consider a subdivision invariant action for dynamically triangulated random surfaces that was recently proposed (R.V. Ambartzumian et. al., Phys. Lett. B 275 (1992) 99) and show that it is unphysical: The grand canonical partition function is infinite for all values of the coupling constants. We conjecture that adding the area action to the action of Ambartzumian et. al. leads to a well-behaved theory.