ShantanuT01/DACTYL-Pretraining huggingface dataset:
A ferromagnetic insulating (FM-I) state in Pr0.75Ca0.25MnO3 has been studied by neutron scattering experiment and theoretical calculation. The insulating behavior is robust against an external magnetic field, and is ascribed to neither the phase separation between a ferromagnetic metallic (FM-M) phase and a non-ferromagnetic insulating one, nor the charge ordering. We found that the Jahn-Teller type lattice distortion is much weaker than PrMnO3 and the magnetic interaction is almost isotropic. These features resembles the ferromagnetic metallic state of manganites, but the spin exchange interaction J is much reduced compared to the FM-M state. The theoretical calculation based on the staggered type orbital order well reproduces several features of the spin and orbital state in the FM-I phase.
The classical Ramsey theorem was generalized in two major ways: to the dual Ramsey theorem, by Graham and Rothschild, and to Ramsey theorems for trees, initially by Deuber and Leeb. Bringing these two lines of thought together, we prove the dual Ramsey theorem for trees. Galois connections between partial orders are used in formulating this theorem, while the abstract approach to Ramsey theory, we developed earlier, is used in its proof.
Motivated by the discovery of the non-thermal Fermi bubble features both below and above the Galactic plane, we investigate a scenario in which these bubbles are formed through Galacto-centric outflow. Cosmic rays (CR) both diffusing and advecting within a Galactic breeze outflow, interacting with the ambient gas present, give rise to gamma-ray emission, providing an approximately flat surface brightness profile of this emission, as observed. Applying the same outflow profile further out within the disk, the resultant effects on the observable CR spectral properties are determined. A hardening in the spectra due to the competition of advective and diffusive propagation within a particular energy range is noted, even in the limiting case of equal CR diffusion coefficients in the disk and halo. It is postulated that this hardening effect may relate to the observed hardening feature in the CR spectrum at a rigidity of $\approx 200$ GV.
We consider the radiation of particles of one bunch in the collective field of the oncoming bunch, called coherent bremsstrahlung (CBS). The main characteristics of CBS for LHC (in the Pb-Pb mode) and for RHIC are calculated. At LHC about $3.9 10^8 dE_\gamma/E_\gamma$ photons per second are expected for photon energies $E_\gamma \stackrel{<} {\sim} E_c= 93 $ eV. It seems that CBS can be a potential tool for optimizing collisions and for measuring beam parameters. The bunch length can be found from the critical energy of the CBS spectrum; the transverse bunch size is related to the photon rate. A specific dependence of photon rate on the impact parameter between the beams allows for a fast control over the beam displacement.
In this paper, we present a comprehensive theory of generalized and weak generalized convolutions, illustrate it by a large number of examples, and discuss the related infinitely divisible distributions. We consider L\'{e}vy and additive process with respect to generalized and weak generalized convolutions as certain Markov processes, and then study stochastic integrals with respect to such processes. We introduce the representability property of weak generalized convolutions. Under this property and the related weak summability, a stochastic integral with respect to random measures related to such convolutions is constructed.
Luminous Compact Blue Galaxies (LCBGs) are compact, star-forming galaxies that are rarely observed in the local universe but abundant at z=1. This increase in LCBG number density over cosmic lookback time roughly follows the increase in the star formation rate density of the universe over the same period. We use publicly available data in the COSMOS field to study the evolution of the largest homogeneous sample of LCBGs to date by deriving their luminosity function in four redshift bins over the range $0.1\leq~z\leq1$. We find that over this redshift range, the characteristic luminosity (M$^{*}$) increases by $\sim$0.2 mag, and the number density increases by a factor of four. While LCBGs make up only about $18\%$ of galaxies more luminous than M$_{B}=-$18.5 at $z\sim0.2$, they constitute roughly $54\%$ at z$\sim$0.9. The strong evolution in number density indicates that LCBGs are an important population of galaxies to study in order to better understand the decrease in the star formation rate density of the universe since $z\sim1$.
The \emph{silent universe conjecture} (Sopuerta 1997, van Elst et al. 1997) states that the only algebraically general silent universes are the orthogonally spatially homogeneous Bianchi I models. In the same paper by Sopuerta this was confirmed for the subcase where the spacetime also admits a group G3 of isometries. However the proof contains a conceptual mistake. We recover the result in a different way.
The paper contains a brief review of recent results on hidden symmetries in higher dimensional black hole spacetimes. We show how the existence of a principal CKY tensor (that is a closed non-degenerate conformal Killing-Yano 2-form) allows one to generate a `tower' of Killing-Yano and Killing tensors responcible for hidden symmetries. These symmetries imply complete integrability of geodesic equations and the complete separation of variables in the Hamilton-Jacobi, Klein-Gordon and Dirac equations in the general Kerr-NUT-(A)dS metrics.
Searches for planetary transits find many astrophysical false positives as a by-product. There are four main types analyzed in the literature: a grazing-incidence eclipsing binary star, an eclipsing binary star with a small radius companion star, a blend of one or more stars with an unrelated eclipsing binary star, and a physical triple star system. We present a list of 69 astrophysical false positives that had been identified as candidates of transiting planets of the on-going XO survey. This list may be useful in order to avoid redundant observation and characterization of these particular candidates independently identified by other wide-field searches for transiting planets. The list may be useful for those modeling the yield of the XO survey and surveys similar to it. Subsequent observations of some of the listed stars may improve mass-radius relations, especially for low-mass stars. From the candidates exhibiting eclipses, we report three new spectroscopic double-line binaries and give mass function estimations for 15 single lined spectroscopic binaries.
This article is a continuation of [Kub18], which proves that if a $3$-dimensional affine normal quasihomogeneous $SL(2)$-variety $E$ is toric, then it has an equivariant resolution of singularities given by an invariant Hilbert scheme $\mathcal H$. In this article, we consider the case where $E$ is non-toric and show that the Hilbert-Chow morphism $\gamma : \mathcal H \to E$ is a resolution of singularities and that $\mathcal H$ is isomorphic to the minimal resolution of a weighted blow-up of $E$.
The success of existing video super-resolution (VSR) algorithms stems mainly exploiting the temporal information from the neighboring frames. However, none of these methods have discussed the influence of the temporal redundancy in the patches with stationary objects and background and usually use all the information in the adjacent frames without any discrimination. In this paper, we observe that the temporal redundancy will bring adverse effect to the information propagation,which limits the performance of the most existing VSR methods. Motivated by this observation, we aim to improve existing VSR algorithms by handling the temporal redundancy patches in an optimized manner. We develop two simple yet effective plug and play methods to improve the performance of existing local and non-local propagation-based VSR algorithms on widely-used public videos. For more comprehensive evaluating the robustness and performance of existing VSR algorithms, we also collect a new dataset which contains a variety of public videos as testing set. Extensive evaluations show that the proposed methods can significantly improve the performance of existing VSR methods on the collected videos from wild scenarios while maintain their performance on existing commonly used datasets. The code is available at https://github.com/HYHsimon/Boosted-VSR.
We report here a new result extracted from the Fermi Large Area Telescope observation of the classical nova ASASSN-16ma that exhibits coherent gamma-ray pulsations at 544.84(7) seconds during its outburst in 2016. Considering the number of independent trials, the significance of the evidence is 4.0 sigma, equivalent to a false alarm probability of 5.9e-5. The periodicity was steady during the 4 days of its appearance, indicating its origin as the spinning signal of the white dwarf. Given that the optical and gamma-ray light curves of some shock-powered gamma-ray novae have been recently shown closely correlated to each other, the gamma-ray pulsation phenomenon likely implies an existence of the associated optical pulsations, which would provide detailed ephemerides for these extreme white dwarf binaries for further investigations in the near future.
We present Fast Fourier Color Constancy (FFCC), a color constancy algorithm which solves illuminant estimation by reducing it to a spatial localization task on a torus. By operating in the frequency domain, FFCC produces lower error rates than the previous state-of-the-art by 13-20% while being 250-3000 times faster. This unconventional approach introduces challenges regarding aliasing, directional statistics, and preconditioning, which we address. By producing a complete posterior distribution over illuminants instead of a single illuminant estimate, FFCC enables better training techniques, an effective temporal smoothing technique, and richer methods for error analysis. Our implementation of FFCC runs at ~700 frames per second on a mobile device, allowing it to be used as an accurate, real-time, temporally-coherent automatic white balance algorithm.
A density functional study is presented of the interstitial Zn$_i$, Ge$_i$, and N$_i$ in ZnGeN$_2$. Corrections to the band gap are included by means of the LDA+U method.   The Zn and Ge interstitials are both found to strongly prefer the larger octahedral site compared to the two types of tetrahedral sites.   The Zn interstitial is found to be a shallow double donor but has higher energy than previously studied antisite defects. It has a resonance in the conduction band which is Zn-$s$ like.   The Ge interstitial is an even higher energy of formation defect and also behaves as a shallow double donor but has also a deep level in the gap, corresponding to a Ge-$s$ orbital character while the Ge-$p$ forms a resonance in the conduction band.   The nitrogen interstitial forms a split-interstitial configuration, as also occurs in GaN. Its electronic levels can be related to that of a N$_2$ molecule. The defect levels in the gap correspond to the $\pi_g$-like lowest unoccupied molecular orbital (LUMO) of the molecule, which here becomes filled with 3 electrons in the defect's neutral charge state. They are found to prefer a high-spin configuration in the $q=+1$ state.   The corresponding transition levels are obtained and show that this is an amphoteric trap level occurring in $+2$, $+1$, 0 and $-1$ charge states. The two possible sites for this split interstitial, on top of Zn or on top of Ge differ slightly in N$_2$ bond-length. While the N$_i$ defects have the lowest formation energy among the interstitials, it is still higher than that of the antisites.   Hence they are not expected to occur in sufficient concentration to affect the intrinsic Fermi level position. In particular, they do not contribute to the unintentional n-type background doping.
We present the results of a search for galaxy clusters and groups in the $\sim2$ square degree of the COSMOS field using all available X-ray observations from the XMM-Newton and Chandra observatories. We reach an X-ray flux limit of $3\times10^{-16}\;ergs\;cm^{-2}\;s^{-1}$ in 0.5--2 keV range, and identify 247 X-ray groups with $M_{200c}=8\times10^{12}-3\times10^{14}\;M_{\odot}$ at a redshift range of $0.08\leq z<1.53$, using the multiband photometric redshift and the master spectroscopic redshift catalogues of the COSMOS. The X-ray centres of groups are determined using high-resolution Chandra imaging. We investigate the relations between the offset of the brightest group galaxies (BGGs) from halo X-ray centre and group properties and compare with predictions from semi-analytic models and hydrodynamical simulations. We find that BGG offset decreases with both increasing halo mass and decreasing redshift with no strong dependence on the X-ray flux and SNR. We show that the BGG offset decreases as a function of increasing magnitude gap with no considerable redshift dependent trend. The stellar mass of BGGs in observations extends over a wider dynamic range compared to model predictions. At $z<0.5$, the central dominant BGGs become more massive than those with large offsets by up to 0.3dex, in agreement with model prediction. The observed and predicted lognormal scatter in the stellar mass of both low- and large-offset BGGs at fixed halo mass is $\sim0.3$dex.
We use a double degeneration technique to calculate the dimension of the secant variety of any Segre-Veronese embedding of (P^1)^r
Nearly parallel vortex filaments are a generalization of point vortices and describe many phenomena under conservation of angular momentum including vortices forming in deep ocean convection, magnetically confined plasmas, and the solar atmosphere. While point vortices represent perfectly straight, parallel lines of circulation, nearly parallel vortex filaments have some curvature due to internal viscosity. They interact logarithmically but have a kinetic self-energy as well. In this letter, I present an exact solution of a system of these filaments under angular momentum conservation in a mean-field theory. I show that the filaments have an infinite order phase transition not present in the point vortex model.
We study the final outcome of gravitational collapse resulting from the plane symmetric charged Vaidya spacetime. Using the field equations, we show that the weak energy condition is always satisfied by collapsing fluid. It is found that the singularity formed is naked. The strength of singularity is also investigated by using Nolan's method. This turns out to be a strong curvature singularity in Tipler's sense and hence provides a counter example to the cosmic censorship hypothesis.
We present a new picture that the $\alpha$-linear-chain structure for ${^{12}{\rm C}}$ and ${^{16}{\rm O}}$ has one-dimensional $\alpha$ condensate character. The wave functions of linear-chain states which are described by superposing a large number of Brink wave functions have extremely large overlaps of nearly $100\%$ with single Tohsaki-Horiuchi-Schuck-R\"opke (THSR) wave functions, which were proposed to describe the $\alpha$ condensed "gas-like" states. Although this new picture is different from the conventional idea of the spatial localization of $\alpha$ clusters, the density distributions are shown to have localized $\alpha$-clusters which is due to the inter-$\alpha$ Pauli repulsion.
We present constraints on the structure of the chromosphere from observations of the Ca II H line profile near and off the solar limb. We obtained a data set of the Ca II H line in a field of view extending 20" across the limb. We analyzed the spectra for the properties of off-limb spectra. We used tracers of the Doppler shifts, such as the location of the absorption core, the ratio of the two emission peaks H2V and H2R, and intensity images at a fixed wavelength. The average off-limb profiles show a smooth variation with increasing limb distance. The line width increases up to a height of about 2 Mm above the limb. The profile shape is fairly symmetric with nearly identical H2V and H2R intensities; at a height of 5 Mm, it changes into a single Gaussian without emission peaks. We find that all off-limb spectra show large Doppler shifts that fluctuate on the smallest resolved spatial scales. The variation is more prominent in cuts parallel to the solar limb than on those perpendicular to it. As far as individual structures can be unequivocally identified at our spatial resolution, we find a specific relation between intensity enhancements and Doppler shifts: elongated brightenings are often flanked all along their extension by velocities in opposite directions. The average off-limb spectra of Ca II H present a good opportunity to test static chromospheric atmosphere models because they lack the photospheric contribution that is present in disk-center spectra. We suggest that the observed relation between intensity enhancements and Doppler shifts could be caused by waves propagating along the surfaces of flux tubes: an intrinsic twist of the flux tubes or a wave propagation inclined to the tube axis would cause a helical shape of the Doppler excursion, visible as opposite velocity at the sides of the flux tube.
We perform a first precision calculation of the transverse-momentum (q_T) distribution of slepton pair and slepton-sneutrino associated production at the CERN Large Hadron Collider (LHC). We implement soft-gluon resummation at the next-to-leading logarithmic (NLL) level and consistently match the obtained result to the pure fixed-order perturbative result at leading order (LO) in the QCD coupling constant, i.e. O(alpha_s). We give numerical predictions for stau_1 stau_1^* and stau_1 sneutrino_tau^* + stau_1^* sneutrino_tau production, also implementing recent parameterizations of non-perturbative effects. The results show a relevant contribution of resummation both in the small and intermediate q_T-regions and little dependence on unphysical scales and non-perturbative contributions.
The concept of the electron localization function (ELF) is extended to two-dimensional (2D) electron systems. We show that the topological properties of the ELF in 2D are considerably simpler than in molecules studied previously. We compute the ELF and demonstrate its usefulness for various physical 2D systems, focusing on semiconductor quantum dots that effectively correspond to a confined 2D electron gas. The ELF visualizes the shell structure of harmonic quantum dots and provides insight into electron bonding in quantum-dot molecules. In external magnetic fields the ELF is found to be a useful measure of vorticity when analyzing the properties of quantum-Hall droplets. We show that the current-dependent term in the ELF expression is important in magnetic fields.
We present high spatial resolution H and K'-band images of a complete sample of ultraluminous infrared galaxies selected to have warm mid-infrared colors known to be characteristic of active galaxies. The extended underlying galaxy is detected in each system, as are tidal features and many of the star-forming knots seen at optical wavelengths. While some of these knots have a considerable near-infrared excess, we show that they are likely to have bolometric luminosities more similar to that of the extended starbursts with similar optical morphology seen in less far-infrared luminous interacting systems. We find that each ULIG has increasing contributions at long wavelengths by a very compact source which we identify as an active galactic nucleus. We show that the optical/near-infrared colors of these putative nuclei are much more extreme than the most active starburst IRAS galaxies, yet are identical to "far-infrared loud" quasars which are in turn similar to optical quasars combined with large quantities of hot dust. Half of the ULIGs have nuclei with dereddened near-infrared luminosities comparable to those of QSOs, while the other half have dereddened luminosities more similar to Seyferts, although this may be an effect of patchy extinction and scattering.
We consider a type of random processes which satisfies the conditional increment condition and obtain an estimate for the tail probability and a Doob-type inequality of the maximum of the process. The main result is that, for processes satisfying the conditional increment condition, the tail probability decay of its maximum behaves in the same way as its marginals.
Genuine-multipartite-entanglement (GME) concurrence is a measure of genuine multipartite entanglement that generalizes the well-known notion of concurrence. We define an observable for GME concurrence. The observable permits us to avoid full state tomography and leads to different analytic lower bounds. By means of explicit examples we show that entanglement criteria based on the bounds have a better performance with respect to the known methods.
We proof the Perelomov identity for arbitrary 2D lattices using Fourier transformation. We further generalize it to situations where the origin does not coincide with a lattice site, and where the form of the exponential factor is reminiscent of magnetic wave functions in uniaxial rather than symmetric gauge.
We study $\gamma_{k}(x_2,...,x_k;t)$, the k-fold renormalized self-intersection local time for Brownian motion in $R^1$. Our main result says that $\gamma_{k}(x_2,...,x_k;t)$ is continuously differentiable in the spatial variables, with probability 1.
The circumstellar environment of L2 Pup, an oxygen-rich semiregular variable, was observed to understand the evolution of mass loss and the shaping of ejecta in the late stages of stellar evolution. High-angular resolution observations from a single 8 m telescope were obtained using aperture masking in the near-infrared (1.64, 2.30 and 3.74 $\rm\mu m$) on the NACO/VLT, both in imaging and polarimetric modes. The aperture-masking images of L2 Pup at 2.30 $\rm\mu m$ show a resolved structure that resembles a toroidal structure with a major axis of ~140 milliarcseconds (mas) and an east-west orientation. Two clumps can be seen on either side of the star, ~65 mas from the star, beyond the edge of the circumstellar envelope (estimated diameter is ~27 mas), while a faint, hook-like structure appear toward the northeast. The patterns are visible both in the imaging and polarimetric mode, although the latter was only used to measure the total intensity (Stokes I). The overall shape of the structure is similar at the 3.74 $\rm\mu m$ pseudo-continuum (dust emission), where the clumps appear to be embedded within a dark, dusty lane. The faint, hook-like patterns are also seen at this wavelength, extending northeast and southwest with the central, dark lane being an apparent axis of symmetry. We interpret the structure as a circumstellar torus with inner radius of 4.2 au. With a rotation velocity of 10 km s$^{-1}$ as suggested by the SiO maser profile, we estimate a stellar mass of 0.7 M$_\odot$.}
For the 3D compressible isentropic Euler equations with an initial perturbation of size $\ve$ of a rest state, if the initial vorticity is of size $\dl$ with $0<\dl\le \ve$ and $\ve$ is small, we establish that the lifespan of the smooth solutions is $T_{\dl}=O(\min\{e^\frac{1}{\ve},\frac{1}{\delta}\})$ for the polytropic gases, and $T_{\dl}=O(\frac{1}{\delta})$ for the Chaplygin gases. For example, when $\dl=e^{-\f{1}{\ve^2}}$ is chosen, then $T_{\dl}=O(e^{\f{1}{\ve}})$ for the polytropic gases and $T_{\dl}=O(e^{\f{1}{\ve^2}})$ for the Chaplygin gases although the perturbations of the initial density and the divergence of the initial velocity are only of order $O(\ve)$. Our result illustrates that the time of existence of smooth solutions depends crucially on the size of the vorticity of the initial data, as long as the initial data is sufficiently close to a constant. The main ingredients in the paper are: introducing some suitably weighted energies, deriving the pointwise space-time decay estimates of solutions, looking for the good unknown instead of the velocity, and establishing the required weighted estimates on the vorticty.