ShantanuT01/DACTYL-Pretraining huggingface dataset:
To effectively retrieve objects from large corpus with high accuracy is a challenge task. In this paper, we propose a method that propagates visual feature level similarities on a Markov random field (MRF) to obtain a high level correspondence in image space for image pairs. The proposed correspondence between image pair reflects not only the similarity of low-level visual features but also the relations built through other images in the database and it can be easily integrated into the existing bag-of-visual-words(BoW) based systems to reduce the missing rate. We evaluate our method on the standard Oxford-5K, Oxford-105K and Paris-6K dataset. The experiment results show that the proposed method significantly improves the retrieval accuracy on three datasets and exceeds the current state-of-the-art retrieval performance.
We assume that the existence and termination conjecture for flips holds. A complex projective manifold is said to be {\it of almost general type} if the intersection number of the canonical divisor with every very general curve is strictly positive. Let $f$ be an algebraic fiber space from $X$ to $Y$. Then the manifold $X$ is of almost general type if every very general fiber $F$ and the base space $Y$ of $f$ are of almost general type.
Magnetic null points can develop near the ergosphere boundary of a rotating black hole by the combined effects of strong gravitational field and the frame-dragging mechanism. The electric component does not vanish in the magnetic null and an efficient process or particle acceleration can occur. The situation is relevant for starving (low-accretion-rate, such as the Milky Way's supermassive black hole) nuclei of some galaxies which exhibit only episodic accretion events. The presence of the magnetic field field of an external origin is an important aspect. We propose that such conditions can develop when a magnetized neutron star approaches the supermassive black hole during late stages of its inspiral motion. The field lines of the neutron star dipole thread the black hole's event horizon and change rapidly their connectivity. We put in comparison the case of a dipole-type magnetic field of a sinking and orbiting star near a non-rotating black hole, and the near-horizon structure of an asymptotically uniform magnetic field of a distant source near a fast-rotating black hole. Although the two cases are qualitatively different from each other, they both develop magnetically neutral null points near the event horizon.
We consider the two-dimensional one-component plasma (jellium) of mobile pointlike particles with the same charge $e$, interacting pairwisely by the logarithmic Coulomb potential and immersed in a fixed neutralizing background charge density. Particles are in thermal equilibrium at the inverse temperature $\beta$, the only relevant dimensionless parameter is the coupling constant $\Gamma\equiv\beta e^2$. In the bulk fluid regime and for any value of the coupling constant $\Gamma=2\times{\rm integer}$, \v{S}amaj and Percus [J. Stat. Phys. {\bf 80}, 811--824 (1995)] have derived an infinite sequence of sum rules for the coefficients of the short-distance expansion of particle pair correlation function. In the context of the equivalent fractional quantum Hall effect, by using specific methods of quantum geometry Haldane [PRL {\bf 107}, 116801 (2011) and arXiv:1112.0990v2] derived a self-dual relation for the Landau-level guiding-center structure factor. In this paper, we establish the relation between the guiding-center structure factor and the pair correlation function of jellium particles. It is shown that the self-dual formula, which provides an exact relation between the pair correlation function and its Fourier component, comes directly from the short-distance symmetry of the bulk jellium. The short-distant symmetry of pair correlations is extended to the semi-infinite geometry of a rectilinear plain hard wall with a fixed surface charge density, constraining particles to a half-space. The symmetry is derived for the original jellium model as well as its simplified version with no background charge (charged wall surface with ``counter-ions only''). The obtained results are checked at the exactly solvable free-fermion coupling $\Gamma=2$.
We prove a complete convergence theorem for a class of symmetric voter model perturbations with annihilating duals. A special case of interest covered by our results is the stochastic spatial Lotka-Volterra model introduced by Neuhauser and Pacala [Ann. Appl. Probab. 9 (1999) 1226-1259]. We also treat two additional models, the "affine" and "geometric" voter models.
We present ALMA 870-um (345GHz) observations of two sub-millimetre galaxies (SMGs) drawn from an ALMA study of the 126 sub-millimeter sources from the LABOCA Extended Chandra Deep Field South Survey (LESS). The ALMA data identify the counterparts to these previously unidentified sub-millimeter sources and serendipitously detect bright emission lines in their spectra which we show are most likely to be [C II]157.74um emission yielding redshifts of z=4.42 and z=4.44. This blind detection rate within the 7.5-GHz bandpass of ALMA is consistent with the previously derived photometric redshift distribution of SMGs and suggests a modest, but not dominant (<25%), tail of 870-um selected SMGs at z>4. We find that the ratio of L_CII/L_FIR in these SMGs is much higher than seen for similarly far-infrared-luminous galaxies at z~0, which is attributed to the more extended gas reservoirs in these high-redshift ULIRGs. Indeed, in one system we show that the [C II] emission shows hints of extended emission on >3kpc scales. Finally, we use the volume probed by our ALMA survey to show that the bright end of the [C II] luminosity function evolves strongly between z=0 and z~4.4, reflecting the increased ISM cooling in galaxies as a result of their higher star-formation rates. These observations demonstrate that even with short integrations, ALMA is able to detect the dominant fine structure cooling lines from high-redshift ULIRGs, measure their energetics and trace their evolution with redshift.
In the present work we study the propagation of a probe minimally coupled scalar field in Einstein-power-Maxwell charged black hole background in (1+2) dimensions. We find analytical expressions for the reflection coefficient as well as for the absorption cross-section in the low energy regime, and we show graphically their behaviour as functions of the frequency for several values of the free parameters of the theory.
We study numerically the so-called ``turn-over scenario'' for rotating magnetic white dwarfs and neutron stars. According to this scenario, the magnetic symmetry axis of the model inclines at a gradually increasing angle (the so-called ``turn-over angle'') relative to the invariant angular momentum axis. Consequently, the model becomes ``perpendicular rotator'' (i.e., its turn-over angle becomes almost 90 degrees) on a ``turn-over timescale'' calculated to be ~ (a few)x10^6 - (a few)x10^7 yr for the examined white dwarf models and ~ 10^1 - 10^3 yr for the examined neutron star models. Furthermore, the initial differential rotation of the model turns to uniform rotation due to angular momentum mixing caused by hydrodynamic Alfven waves propagating along the poloidal magnetic field lines. Our numerical results show that, during the turn-over phase, the spin-down time rate is large, while the spin-down power remains small; so, the turn-over phase is a characteristic case for which an eventually observed large spin-down time rate should not be interpreted as implying a large spin-down power.
We present a method for including inelastic scattering in a first-principles density-functional computational scheme for molecular electronics. As an application, we study two geometries of four-atom gold wires corresponding to two different values of strain, and present results for nonlinear differential conductance vs. device bias. Our theory is in quantitative agreement with experimental results, and explains the experimentally observed mode selectivity. We also identify the signatures of phonon heating.
We used \ha-0.1 nm and magnetic field (at 1.56$\mu$) data obtained with the New Solar Telescope to study the origin of the disk counterparts to type II spicules, so-called rapid blueshifted excursions (RBEs). The high time cadence of our chromospheric (10 s) and magnetic field (45 s) data allowed us to generate x-t plots using slits parallel to the spines of the RBEs. These plots, along with potential field extrapolation, led us to suggest that the occurrence of RBEs is generally correlated with the appearance of new, mixed or unipolar fields in close proximity to network fields. RBEs show a tendency to occur at the interface between large-scale fields and small-scale dynamic magnetic loops and thus are likely to be associated with existence of a magnetic canopy. Detection of kinked and/or inverse "Y" shaped RBEs further confirm this conclusion.
We relate $\phi(\bf{x},s)$, the average number of sites at a transverse distance $\bf{x}$ in the directed animals with $s$ sites in $d$ transverse dimensions, to the two-point correlation function of a lattice gas with nearest neighbor exclusion in $d$ dimensions. For large $s$, $\phi(\bf{x},s)$ has the scaling form $\frac{s}{R_s^d} f(|\bf{x}|/R_s)$, where $R_s$ is the root mean square radius of gyration of animals of $s$ sites. We determine the exact scaling function for $d =1$ to be $f(r) = \frac{\sqrt{\pi}}{2 \sqrt{3}}erfc(r/\sqrt{3})$. We also show that $\phi(\bf{x}=0,s)$ can be determined in terms of the animals number generating function of the directed animals.
We introduce elliptic and parabolic $\mathcal{B}_{1}$ classes that generalize the well-known $\mathfrak{B}_{p}$ classes of DeGiorgi, Ladyzhenskaya and Ural'tseva with $p>1$. New classes are applied to prove pointwise continuity of solutions of elliptic and parabolic equations with nonstandard growth conditions. Our considerations cover new cases of variable exponent and $(p, q)$-phase growth including the ,,singular-degenerate'' parabolic case $p<2<q$.
Muon lepton flavor processes are reviewed in connection with search for physics beyond the standard model. Several methods to distinguish different theoretical models are discussed for $\mu \to e \gamma$, $\mu \to 3 e$, and $\mu - e$ conversion processes. New calculation of the $\mu - e$ conversion rate is presented including a Higgs boson mediated effect in the supersymmetric seesaw model.
We study the problem of self-energy of pointlike charges in higher dimensional static spacetimes. Their energy, as a functional of the spacetime metric, is invariant under a specific continuous transformation of the metric. We show that the procedure of regularization of this formally divergent functional breaks this symmetry and results in an anomalous contribution to the finite renormalized self-energy. We proposed a method of calculation of this anomaly and presented an explicit expressions for it in the case of a scalar charge in four and five-dimensional static spacetimes. This anomalous correction proves to be zero in even dimensions, but it does not vanish in odd-dimensional spacetimes.
In order to investigate the nuclear activity of galaxies residing in compact groups of galaxies, we present results of our optical spectroscopic program made at Okayama Astrophysical Observatory. We have performed optical spectroscopy of 69 galaxies which belong to 31 Hickson Compact Groups (HCGs) of Galaxies. Among them, three galaxies have discordant redshifts. Further, spectral quality is too poor to classify other three galaxies. Therefore, we describe our results for the remaining 63 galaxies.   Our main results are summarized below. (1) We have found in our sample; 28 AGN, 16 HII nuclei, and 19 normal galaxies which show no emission line. We used this HCG sample for statistical analyses. (2) Comparing the frequency distributions of activity types between the HCGs and the field galaxies whose data are taken from Ho, Filippenko, & Sargent (382 field galaxies), we find that the frequency of HII nuclei in the HCGs is significantly less than that in the field. However, this difference may be due to selection bias that our HCG sample contains more early-type galaxies than the field, because it is known that HII nuclei are rarer in early-type galaxies than in later ones. (3) Applying correction this morphological bias to the HCG sample, we find that there is no statistically significant difference in the frequency of occurrence of emission-line galaxies between the HCGs and the field. This implies that the dense galaxy environment in the HCGs does not affect triggering both the AGN activity and the nuclear starburst. We discuss some implications on the nuclear activity in the HCG galaxies.
The isoscalar monopole(ISM) and dipole(ISD) excitations in $^{12}$C are theoretically investigated with the shifted antisymmetrized molecular dynamics(AMD) plus $3\alpha$-cluster generator coordinate method(GCM). The small amplitude vibration modes are described by coherent one-particle one-hole excitations expressed by small shift of single-nucleon Gaussian wave functions within the AMD framework, whereas the large amplitude cluster modes are incorporated by superposing $3\alpha$-cluster wave functions in the GCM. The coupling of the excitations in the intrinsic frame with the rotation and parity transformation is taken into account microscopically by the angular-momentum and parity projections. The present calculation describes the ISM and ISD excitations in a wide energy region covering cluster modes in the low-energy region and the giant resonances in the high-energy region, though the quantitative description of the high-energy part is not satisfactory. The low-energy ISM and ISD strengths of the cluster modes are enhanced by the radial motion of $\alpha$ clusters, and they split into a couple of states because of the angular motion of $\alpha$ clusters. The low-energy ISM strengths exhaust 26% of the EWSR, which is consistent with the experimental data for the $^{12}$C($0^+_2$;7.65 MeV) and $^{12}$C($0^+_3$;10.3 MeV) measured by $(e,e')$, $(\alpha,\alpha')$, and ($^6$Li,$^6$Li$'$) scatterings. In the calculated low-energy ISD strengths, two $1^-$ states (the $1^-_1$ and $1^-_2$) with the significant strengths are obtained in $E=10-15$ MeV. It is indicated that the ISD excitations can be a good probe to experimentally search for new cluster states such as the $^{12}$C($1^-_2$) obtained in the present calculation.
We use a temperature map of the cosmic microwave background (CMB) obtained using the South Pole Telescope at 150 GHz to construct a map of the gravitational convergence to z ~ 1100, revealing the fluctuations in the projected mass density. This map shows individual features that are significant at the ~ 4 sigma level, providing the first image of CMB lensing convergence. We cross-correlate this map with Herschel/SPIRE maps covering 90 square degrees at wavelengths of 500, 350, and 250 microns. We show that these submillimeter-wavelength (submm) maps are strongly correlated with the lensing convergence map, with detection significances in each of the three submm bands ranging from 6.7 to 8.8 sigma. We fit the measurement of the cross power spectrum assuming a simple constant bias model and infer bias factors of b=1.3-1.8, with a statistical uncertainty of 15%, depending on the assumed model for the redshift distribution of the dusty galaxies that are contributing to the Herschel/SPIRE maps.
By quantizing an open string ending on a D-brane in a nontrivial supergravity background, we argue that there is a new kind of uncertainty relation on a D-brane worldvolume. Furthermore, we fix the form of the uncertainty relations and their dependence on the string coupling constant by requiring them to be consistent with various string theory and M theory dualities. In this way we find a web of uncertainties of spacetime for all kinds of brane probes, including fundamental strings, D-branes of all dimensions as well as M theory membranes and fivebranes.
Enstrophy, half the integral of the square of vorticity, plays a role in 2D turbulence theory analogous to that played by kinetic energy in the Kolmogorov theory of 3D turbulence. It is therefore interesting to obtain a description of the way enstrophy is dissipated at high Reynolds number. In this article we explore the notions of viscous and transport enstrophy defect, which model the spatial structure of the dissipation of enstrophy. These notions were introduced by G. Eyink in an attempt to reconcile the Kraichnan-Batchelor theory of 2D turbulence with current knowledge of the properties of weak solutions of the equations of incompressible and ideal fluid motion. Three natural questions arise from Eyink's theory: (1) Existence of the enstrophy defects (2) Conditions for the equality of transport and viscous enstrophy defects (3) Conditions for the vanishing of the enstrophy defects. In [Nonlinearity, v 14 (2001) 787-802], Eyink proved a number of results related to these questions and formulated a conjecture on how to answer these problems in a physically meaningful context. In the present article we improve and extend some of Eyink's results and present a counterexample to his conjecture.
In this thesis we will work under the premises of the Cellular Automata Interpretation of QM, by Gerard 't Hooft, according to whom particles evolve following the rules of Cellular Automata (CA), a mathematical model consisting of discrete units that evolve following deterministic laws in discrete space and time. The states of a Cellular Automaton are, by definition, classical and thus deterministic and do not form superpositions.   Since it is not possible to know how to demonstrate the underlying classical deterministic structure and dynamics at the smallest microscopic scales at present, what we pursue in this thesis, besides summarizing the concept of the Cellular Automaton Interpretation, is to show that quantum phenomena, in particular superposition states, can arise in a deterministic model because of the limited precision of measurements. In order to do that, we follow the path of a recent article by Elze, considering a triplet of Ising spins and their dynamics in a CA context, which is possible to formalize using Pauli matrices and quantum mechanics operators. We will thus observe how the system will shift from a triplet of Ising spins to a triplet of qubits due to the arising of superposition after applying some perturbations on the Hamiltonian and the dynamics operators.
I derive analytic scalings for coronagraphic imaging searches for extrasolar planets. I compute the efficiency of detecting planets about any given star, and from this compute dimensionless distribution functions for the detected planets as a function of planet-star distance and distance to the host stars. I find the following for blind planet surveys: (1) the optimum wavelength is between 4000-5000 Angstroms for Earth-like planets and 4200-5800 Angstroms for Jovian planets; (2) between 21-32% of the number of planets per decade of radius can be detected with an optimized survey; (3) target stars should be ranked from greatest to least by their luminosity divided by distance to the sixth or eighth power, depending on the dominant source of noise for the survey; (4) surveys targeting all main sequence stars will detect ~3 times as many planets as surveys only targeting G-type stars; and (5) stellar populations with different metallicities should have exposure times that vary with the cube of the metallicity. I apply these results to the current suite of proposed coronagraphic satellite telescopes, of which TPF-C is the most powerful, but a much smaller telescope, TOPS, may have a significant chance of detecting Earth-sized planets due to its small inner working angle and high throughput. The most significant uncertainty in these results is the noise contribution of Exo-zodiacal light. These results can be applied to designing coronagraphs, comparing proposed telescope designs, optimizing the observing strategies, determining the properties of detected planet populations, and selecting target stars.
We prove that, given a stress-free, axially symmetric elastic body, there exists, for sufficiently small values of the gravitational constant and of the angular frequency, a unique stationary axisymmetric solution to the Einstein equations coupled to the equations of relativistic elasticity with the body performing rigid rotations around the symmetry axis at the given angular frequency.
This text is a draft of the review paper on projectively dual varieties. Topics include dual varieties, Pyasetskii pairing, discriminant complexes, resultants and schemes of zeros, secant and tangential varieties, Ein theorems, applications of projective differential geometry and Mori theory to dual varieties, degree and multiplicities of discriminants, self-dual varieties, etc.
In this paper we study the Hardy problem in R^N with N>2 and in a ball B of R^N. Using a suitable map we transform the Hardy problem into another one without the singular term. Then we obtain some bifurcation results from the radial positive solutions corresponding to some explicit values of the parameter lambda.
We study the structural properties of Low Surface Brightness galaxies (LSB) using a sample of 263 galaxies observed by the Green Bank Telescope (Schneider et al 1992). We perform 2D decompositions of these galaxies in the SDSS $g$, $r$ and $i$ bands using the GALFIT software. Our decomposition reveals that about $60\%$ of these galaxies are bulgeless i.e., their light distributions are well modelled by pure exponential disks. The rest of the galaxies were fitted with two components: a Sersic bulge and an exponential disk. Most of these galaxies have bulge-to-total (B/T) ratio less than 0.1. However, of these 104 galaxies, $20\%$ have $B/T > 0.1$ i.e., hosting significant bulge component and they are more prominent amongst the fainter LSBs. According to $g - r$ colour criteria, most of the LSB galaxies in our sample are blue, with only 7 classified as red LSBs. About $15\%$ of the LSB galaxies (including both blue and red) in our sample host stellar bars. The incidence of bars is more prominent in relatively massive blue LSB galaxies with very high gas fraction. These findings may provide important clues to the formation and evolution of LSB galaxies - in particular on the bar/bulge formation in faint LSB disks.
We study multiple eigenvalues of a magnetic Aharonov-Bohm operator with Dirichlet boundary conditions in a planar domain. In particular, we study the structure of the set of the couples position of the pole-circulation which keep fixed the multiplicity of a double eigenvalue of the operator with the pole at the origin and half-integer circulation. We provide sufficient conditions for which this set is made of an isolated point. The result confirms and validates a lot of numerical simulations available in preexisting literature.
Nous d\'ecrivons quelques r\'esultats r\'ecents sur la suite de Thue-Morse, ainsi que des questions ou conjectures, dont l'une, due \`a Shevelev, est r\'esolue dans cet article.   We describe some recent results on the Thue-Morse sequence. We also list open questions and conjectures, one of which is due to Shevelev and proved in this paper.