ShantanuT01/DACTYL-Pretraining huggingface dataset:
We present the results of $WBVR$ observations of the low-mass X-ray binary V1341 $\textrm{Cyg} = \textrm{Cyg}$ X--2. Our observations include a total of 2375 individual measurements in four bands on 478 nights in 1986-1992. We tied the comparison and check stars used for the binary to the $WBVR$ catalog using their $JHK$ magnitudes. The uncertainty of this procedure was 3$%$ in the $B$ and $V$ bands and 8%-10% for the $W$ and $R$ bands. In quiescence, the amplitude of the periodic component in the binary's $B$ brightness variations is within $0.265^{m}{-}0.278^{m}$ ($0.290^{m}{-}0.320^{m}$ in $W$); this is due to the ellipsoidal shape of the optical component, which is distorted with gravitational forces from the X-ray component. Some of the system's active states (long flares) may be due to instabilities in the accretion disk, and possibly to instabilities of gas flows and other accretion structures. The binary possesses a low-luminosity accretion disk. The light curves reveal no indications of an eclipse near the phases of the upper and lower conjunctions in quiescence or in active states during the observed intervals. We conclude that the optical star in the close binary V1341 $\textrm{Cyg} = \textrm{Cyg}$ X-2 is a red giant rather than a blue straggler. We studied the long-term variability of the binary during the seven years covered by our observations. The optical observations presented in this study are compared to X-ray data from the Ginga observatory for the same time intervals.
Let $K$ be a number field. In the terminology of Nagell a unit $\varepsilon$ of $K$ is called {\it exceptional} if $1-\varepsilon$ is also a unit. The existence of such a unit is equivalent to the fact that the unit equation $\varepsilon_1+\varepsilon_2+\varepsilon_3=0$ is solvable in units $\varepsilon_1,\varepsilon_2,\varepsilon_3$ of $K$. Numerous number fields have exceptional units. They have been investigated by many authors, and they have important applications.   In this paper we deal with a generalization of exceptional units. We are interested in the smallest integer $k$ with $k\geq 3$, denoted by $\ell(K)$, such that the unit equation $\varepsilon_1+\dots+\varepsilon_k=0$ is solvable in units $\varepsilon_1,\dots,\varepsilon_k$ of $K$. If no such $k$ exists, we set $\ell(K)=\infty$. Apart from trivial cases when $\ell(K)=\infty$, we give an explicit upper bound for $\ell(K)$. We obtain several results for $\ell(K)$ in number fields of degree at most $4$, cyclotomic fields and general number fields of given degree. We prove various properties of $\ell(K)$, including its magnitude, parity as well as the cardinality of number fields $K$ with given degree and given odd resp. even value $\ell(K)$.   Finally, as an application, we deal with certain arithmetic graphs, namely we consider the representability of cycles. We conclude the paper by listing some problems and open questions.
We update the upper bound on the lightest CP even Higgs mass in the NMSSM, which is given as a function of tan(beta) and lambda. We include the available one and two loop corrections to the NMSSM Higgs masses, and constraints from the absence of Landau singularities below the GUT scale as well as from the stability of the NMSSM Higgs potential. For m_top varying between 171.4 and 178 GeV, squark masses of 1 TeV and maximal mixing the upper bound is assumed near tan(beta) ~ 2 and varies between 139.9 and 141.4 GeV.
An appealing mechanism for inducing multiferroicity in materials is the generation of electric polarization by a spatially varying magnetization that is coupled to the lattice through the spin-orbit interaction. Here we describe the reciprocal effect, in which a time-dependent electric polarization induces magnetization even in materials with no existing spin structure. We develop a formalism for this dynamical multiferroic effect in the case for which the polarization derives from optical phonons, and compute the strength of the phonon Zeeman effect, which is the solid-state equivalent of the well-established vibrational Zeeman effect in molecules, using density functional theory. We further show that a recently observed behavior -- the resonant excitation of a magnon by optically driven phonons -- is described by the formalism. Finally, we discuss examples of scenarios that are not driven by lattice dynamics and interpret the excitation of Dzyaloshinskii-Moriya-type electromagnons and the inverse Faraday effect from the viewpoint of dynamical multiferroicity.
The construction of models for video action classification progresses rapidly. However, the performance of those models can still be easily improved by ensembling with the same models trained on different modalities (e.g. Optical flow). Unfortunately, it is computationally expensive to use several modalities during inference. Recent works examine the ways to integrate advantages of multi-modality into a single RGB-model. Yet, there is still a room for improvement. In this paper, we explore the various methods to embed the ensemble power into a single model. We show that proper initialization, as well as mutual modality learning, enhances single-modality models. As a result, we achieve state-of-the-art results in the Something-Something-v2 benchmark.
We present HST STIS/G140M spectra of 15 extragalactic targets, which we combine with GHRS/G160M data to examine the statistical properties of the low-z Ly-alpha forest. We evaluate the physical properties of these Ly-alpha absorbers and compare them to their high-z counterparts. We determine that the warm, photoionized IGM contains 29+/-4% of the total baryon inventory at z = 0. We derive the distribution in column density, N_HI^(1.65+/-0.07) for 12.5 < log [N_HI] < 14.5, breaking to a flatter slope above log [N_HI] > 14.5. The slowing of the number density evolution of high-W Ly-alpha clouds is not as great as previously measured, and the break to slower evolution may occur later than previously suggested (z~1.0 rather than 1.6). We find a 7.2sigma excess in the two-point correlation function (TPCF) of Ly-alpha absorbers for velocity separations less than 260 km/s, which is exclusively due to the higher column density clouds. From our previous result that higher column density Ly-alpha clouds cluster more strongly with galaxies, this TPCF suggests a physical difference between the higher and lower column density clouds in our sample.
In this paper, we investigate the problems of Cauchy theory and exponential stability for the inhomogeneous Boltzmann equation without angular cut-off. We only deal with the physical case of hard potentials type interactions (with a moderate angular singularity). We prove a result of existence and uniqueness of solutions in a close-to-equilibrium regime for this equation in weighted Sobolev spaces with a polynomial weight, contrary to previous works on the subject, all developed with a weight prescribed by the equilibrium. It is the first result in this more physically relevant frameworkfor this equation. Moreover, we prove an exponential stability for such a solution, with a rate as close as we want to the optimal rate given by the semigroup decay of the linearized equation. Let us highlight the fact that a key point of the development of our Cauchy theory is the proof of new regularization estimates in short time for the linearized operator thanks to pseudo-differential tools.
We present results from extensive broadband follow-up of GRB 210204A over the period of thirty days. We detect optical flares in the afterglow at 7.6 x 10^5 s and 1.1 x 10^6 s after the burst: the most delayed flaring ever detected in a GRB afterglow. At the source redshift of 0.876, the rest-frame delay is 5.8 x 10^5 s (6.71 d). We investigate possible causes for this flaring and conclude that the most likely cause is a refreshed shock in the jet. The prompt emission of the GRB is within the range of typical long bursts: it shows three disjoint emission episodes, which all follow the typical GRB correlations. This suggests that GRB 210204A might not have any special properties that caused late-time flaring, and the lack of such detections for other afterglows might be resulting from the paucity of late-time observations. Systematic late-time follow-up of a larger sample of GRBs can shed more light on such afterglow behaviour. Further analysis of the GRB 210204A shows that the late time bump in the light curve is highly unlikely due to underlying SNe at redshift (z) = 0.876 and is more likely due to the late time flaring activity. The cause of this variability is not clearly quantifiable due to the lack of multi-band data at late time constraints by the bad weather conditions. The flare of GRB 210204A is the latest flare detected to date.
We outline a reduction scheme for a class of Brownian dynamics which leads to meaningful corrections to the Smoluchowski equation in the overdamped regime. The mobility coefficient of the reduced dynamics is obtained by exploiting the Dynamic Invariance principle, whereas the diffusion coefficient fulfils the Fluctuation-Dissipation theorem. Explicit calculations are carried out in the case of a harmonically bound particle. A quantitative pointwise representation of the reduction error is also provided and connections to both the Maximum Entropy method and the linear response theory are highlighted. Our study paves the way to the development of reduction procedures applicable to a wider class of diffusion processes.
The formation of bars in disk galaxies is a tracer of the dynamical maturity of the population. Previous studies have found that the incidence of bars in disks decreases from the local Universe to z ~ 1, and by z > 1 simulations predict that bar features in dynamically mature disks should be extremely rare. Here we report the discovery of strong barred structures in massive disk galaxies at z ~ 1.5 in deep rest-frame optical images from CANDELS. From within a sample of 876 disk galaxies identified by visual classification in Galaxy Zoo, we identify 123 barred galaxies. Selecting a sub-sample within the same region of the evolving galaxy luminosity function (brighter than L*), we find that the bar fraction across the redshift range 0.5< z < 2 (f_bar = 10.7 +6.3 -3.5% after correcting for incompleteness) does not significantly evolve. We discuss the implications of this discovery in the context of existing simulations and our current understanding of the way disk galaxies have evolved over the last 11 billion years.
Using the Born-Oppenheimer approximation, we derive an effective Hamiltonian for an optomechanical system that leads to a nonlinear Kerr effect in the system's vacuum. The oscillating mirror at one edge of the optomechanical system induces a squeezing effect in the intensity spectrum of the cavity field. A near-resonant laser field is applied at the other edge to drive the cavity field, in order to enhance the Kerr effect. We also propose a quantum-nondemolition-measurement setup to monitor a system with two cavities separated by a common oscillating mirror, based on our effective Hamiltonian approach.
In this report we propose that a charge rearrangement within heavy ions may occur during fusion reactions, lowering the Coulomb barrier as the nuclear systems approach each other. In this situation a modified Gamow factor has been calculated, which emphasizes the importance of spatial degrees of freedom in nuclear matter.
Theoretical predictions for the ensemble quasar structure function are tested using multi-epoch observations of Stripe 82 collected by the Sloan Digital Sky Survey. We reanalyze the entire available volume of the g-band imaging data using difference image photometry and build high quality light curves for 7562 spectroscopically confirmed quasars. Our structure function includes ~4.8x10^6 pairs of measurements and covers a wide range of time lags between 3 days and 6.9 years in the quasar rest frame. A broken power-law fit to this data shows the presence of two slopes alpha_1=0.33 and alpha_2=0.79 with the break at ~42 days. The structure function compiled using only flux increases is slightly lower than that for variations of the opposite sign, revealing a slight asymmetry between the leading and trailing edge of a typical flare. The reality of these features is confirmed with monte-carlo simulations. We give simple interpretation of the results in the frames of existing theoretical models.
We experimentally investigate the relative advantages of implementing weak-value-based metrology versus standard methods. While the techniques outlined herein apply more generally, we measure small optical beam deflections both using a Sagnac interferometer with a monitored dark port (the weak-value-based technique), and by focusing the entire beam to a split detector (the standard technique). By introducing controlled external transverse detector modulations and transverse beam deflection momentum modulations, we quantify the mitigation of these sources in the weak-value-based experiment versus the standard focusing experiment. The experiments are compared using a combination of deterministic and stochastic methods. In all cases, the weak-values technique performs the same or better than the standard technique by up to two orders of magnitude in precision for our parameters. We further measure the statistical efficiency of the weak-values-based technique. By postselecting on $1\%$ of the photons, we obtain $99\%$ of the available Fisher information of the beam deflection parameter.
A numerical method to solve time-dependent Hartree-Fock-Bogoliubov equation is proposed to treat the case with Gogny effective interaction. To check the feasibility of the method, it is applied to oxygen isotope O20 and small amplitude oscillations are calculated. The conservation of the nucleon numbers as well as energy expectation value is demonstrated. The strength distributions of the small amplitude quadrupole oscillations are also shown.
We present a flavor model with the $S_3$ modular invariance in the framework of SU(5) GUT. The $S_3$ modular forms of weights $2$ and $4$ give the quark and lepton mass matrices with a common complex parameter, the modulus $\tau$. The GUT relation of down-type quarks and charged leptons is imposed by the VEV of adjoint 24-dimensional Higgs multiplet in addition to the VEVs of $5$ and $\bar 5$ Higgs multiples of SU(5). The observed CKM and PMNS mixing parameters as well as the mass eigenvalues are reproduced properly. We discuss the leptonic CP phase and the effective mass of the neutrinoless double beta decay with the sum of neutrino masses.
The asymptotics of sizes of clusters for the Arratia flow is considered, the Arratia flow being a system of coalescing Wiener processes starting from the real axis and independent before they meet. A cluster at time t is defined as a set of particles that have glued together not later than at t. The results obtained are remarked to hold for any Arratia flow with a Lipschitz drift.
The spherically symmetric reduction of higher dimensional Einstein-scalar theory leads to lower dimensional dilatonic gravity with dilaton coupled scalar (for example, from 4D to 2D system). We calculate trace anomaly and anomaly induced effective action for 2D and 4D dilaton coupled scalars. The large-N effective action for 2D quantum dilaton-scalar gravity is also found. These 2D results maybe applied for analysis of 4D spherical collapse. The role of new, dilaton dependent terms in trace anomaly for 2D black holes and Hawking radiation is investigated in some specific models of dilatonic gravity which represent modification of CGHS model. The conformal sector for 4D dilatonic gravity is constructed. Quantum back-reaction of dilaton coupled matter is briefly discussed (it may lead to the inflationary Universe with non-trivial dilaton).
The Cheshire cat principle states that hadronic observables at low energy do not distinguish between hard (quark) or soft (meson) constituents. As a result, the delineation between hard/soft (bag radius) is like the Cheshire cat smile in Alice in wonderland. This principle reemerges from current holographic descriptions of chiral baryons whereby the smile appears in the holographic direction. We illustrate this point for the baryonic form factor.
We have shown that the study of topological aspects of the underlying geometry in a ferromagnetic spin system gives rise to an intrinsic Berry phase. This real space Berry phase arises due to the spin rotations of conducting electrons which can be manifested as a further contribution in anomalous Hall effect.
Recording atomic-resolution transmission electron microscopy (TEM) images is becoming increasingly routine. A new bottleneck is then analyzing this information, which often involves time-consuming manual structural identification. We have developed a deep learning-based algorithm for recognition of the local structure in TEM images, which is stable to microscope parameters and noise. The neural network is trained entirely from simulation but is capable of making reliable predictions on experimental images. We apply the method to single sheets of defected graphene, and to metallic nanoparticles on an oxide support.
Notwithstanding manufacture of complex organic molecules from impacting cometary and icy planet surface analogues is well-established, dust grain-grain collisions driven by turbulence in interstellar or circumstellar regions may represent a parallel chemical route toward the shock synthesis of prebiotically relevant species. Here we report on a study, based on the multi-scale shock-compression technique combined with ab initio molecular dynamics approaches, where the shock-waves-driven chemistry of mutually colliding isocyanic acid (HNCO) containing icy grains has been simulated by first-principles. At the shock wave velocity threshold triggering the chemical transformation of the sample (7 km/s), formamide is the first synthesized species representing thus the spring-board for the further complexification of the system. In addition, upon increasing the shock impact velocity, formamide is formed in progressively larger amounts. More interestingly, at the highest velocity considered (10 km/s), impacts drive the production of diverse carbon-carbon bonded species. In addition to glycine, the building block of alanine (i.e., ethanimine) and one of the major components of a plethora of amino-acids including, e.g., asparagine, cysteine, and leucine (i.e., vinylamine) have been detected after shock compression of samples containing the most widespread molecule in the universe (H2) and the simplest compound bearing all the primary biogenic elements (HNCO). The present results indicate novel chemical pathways toward the chemical complexity typical of interstellar and circumstellar regions.
In the analytic study of trace functions of $\ell$-adic sheaves over finite fields, a crucial issue is to control the conductor of sheaves constructed in various ways. We consider cohomological transforms on the affine line over a finite field which have trace functions given by linear operators with an additive character of a rational function in two variables as a kernel. We prove that the conductor of such a transform is bounded in terms of the complexity of the input sheaf and of the rational function defining the kernel, and discuss applications of this result, including motivating examples arising from the Polymath8 project.
In this Comment it is argued that Stishov et al. [Phys. Rev. B 86, 064433 (2012)] incorrectly estimated concentrations of (supposed) paramagnetic centers with \mu_eff = 4.8\mu_B in the investigated CoSi crystals. Correct estimation gives concentrations of such centers from 25 to 50 times smaller than reported (appr. 0.04 to 0.16% instead of appr. 2 to 4%). Also the reported data on temperature dependence of resistivity \rho(T) of four CoSi crystals prepared in different Labs are so close to each other at T = 250 to 300K that it is extremely unlikely to be reproducible for any reasonable accuracy of resistivity measurements. These and some other problems of the paper are related to the key points of the authors argumentation. As a result their main conclusions become unjustified.
We attempt to propose a method for automatically detecting the solar filament chirality and barb bearing. We first introduce the unweighted undirected graph concept and adopt the Dijkstra shortest-path algorithm to recognize the filament spine. Then, we use the polarity inversion line (PIL) shift method for measuring the polarities on both sides of the filament, and employ the connected components labeling method to identify the barbs and calculate the angle between each barb and the spine to determine the bearing of the barbs, i.e., left or right. We test the automatic detection method with H-alpha filtergrams from the Big Bear Solar Observatory (BBSO) H-alpha archive and magnetograms observed with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Four filaments are automatically detected and illustrated to show the results. The barbs in different parts of a filament may have opposite bearings. The filaments in the southern hemisphere (northern hemisphere) mainly have left-bearing (right-bearing) barbs and positive (negative) magnetic helicity, respectively. The tested results demonstrate that our method is efficient and effective in detecting the bearing of filament barbs. It is demonstrated that the conventionally believed one-to-one correspondence between filament chirality and barb bearing is not valid. The correct detection of the filament axis chirality should be done by combining both imaging morphology and magnetic field observations.
Characterization of the multipartite mixed state entanglement is still a challenging problem. Since due to the fact that the entanglement for the mixed states, in general, is defined by a convex-roof extension. That is the entanglement measure of a mixed state \r{ho} of a quantum system can be defined as the minimum average entanglement of an ensemble of pure states. In this Letter, we give an explicit formula for the polynomial entanglement measures of degree 2 of even-N qubits mixed states that is similar to Wooters formula in [1]. Then we discuss our findings in the framework of X density matrices and show that our formula for this type of density matrices is in the full agreement with the genuine multipartite (GM) entanglement of these states.
In this paper, we propose a vector total variation (VTV) of feature image model for image restoration. The VTV imposes different smoothing powers on different features (e.g. edges and cartoons) based on choosing various regularization parameters. Thus, the model can simultaneously preserve edges and remove noises. Next, the existence of solution for the model is proved and the split Bregman algorithm is used to solve the model. At last, we use the wavelet filter banks to explicitly define the feature operator and present some experimental results to show its advantage over the related methods in both quality and efficiency.
Going one step further in Zak's classification of Scorza varieties with secant defect equal to one, we characterize the Veronese embedding of $\P^n$ given by the complete linear system of quadrics and its smooth projections from a point as the only smooth irreducible complex and non-degenerate projective subvarieties of $\P^N$ that can be projected isomorphically into $\P^{2n}$ when $N\geq\binom{n+2}{2}-2$.