ShantanuT01/DACTYL-Pretraining huggingface dataset:
The SRa02 of the CoRoT space mission for Asteroseismology was partly devoted to stars belonging to the Mon OB2 association. An intense monitoring was performed on Plaskett's Star (HD47129) and the unprecedented quality of the light curve allows us to shed new light on this very massive, non-eclipsing binary system. We particularly aimed at detecting periodic variability which might be associated with pulsations or interactions between both components. We also searched for variations related to the orbital cycle which could help to constrain the inclination and the morphology of the binary system. A Fourier-based prewhitening and a multiperiodic fitting procedure were applied to analyse the time series and extract the frequencies of variations. We describe the noise properties to tentatively define an appropriate significance criterion, to only point out the peaks at a certain significance level. We also detect the variations related to the orbital motion and study them by using the NIGHTFALL program. The periodogram exhibits a majority of peaks at low frequencies. Among these peaks, we highlight a list of about 43 values, including notably two different sets of harmonic frequencies whose fundamental peaks are located at about 0.07 and 0.82d-1. The former represents the orbital frequency of the binary system whilst the latter could probably be associated with non-radial pulsations. The study of the 0.07d-1 variations reveals the presence of a hot spot most probably situated on the primary star and facing the secondary. The investigation of this unique dataset constitutes a further step in the understanding of Plaskett's Star. These results provide a first basis for future seismic modelling. The existence of a hot region between both components renders the determination of the inclination ambiguous.
We consider geodesics motion in a particular Kundt type III spacetime in which Einstein-Yang-Mills equations admit solutions. On a particular surface as constraint we project the geodesics into the (x,y) plane and treat the problem as a 2-dimensional one. Our numerical study shows that chaotic behavior emerges under reasonable conditions.
We have investigated the flavor changing top quark physics on the dimension-six anomalous $tq\gamma$ ($q=u,c$) couplings through the process $pp\to p\gamma \gamma p\to p t\bar{q}p$ at the LHC by considering different forward detector acceptances. In this paper, we have taken into account and examine the effects of top quark decay. The sensitivity bounds on the anomalous couplings and, $t\to q\gamma$ branching ratio have been obtained at the $95\%$ confidence level for the effective lagrangian approach. Besides, we have investigated the effect of the anomalous couplings on single top quark spin asymmetry.
The sum of all ladder and rainbow diagrams in $\phi^3$ theory near 6 dimensions leads to self-consistent higher order differential equations in coordinate space which are not particularly simple for arbitrary dimension D. We have now succeeded in solving these equations, expressing the results in terms of generalized hypergeometric functions; the expansion and representation of these functions can then be used to prove the absence of renormalization factors which are transcendental for this theory and this topology to all orders in perturbation theory. The correct anomalous scaling dimensions of the Green functions are also obtained in the six-dimensional limit.
In this paper we introduce a novel method to estimate the head pose of people in single images starting from a small set of head keypoints. To this purpose, we propose a regression model that exploits keypoints computed automatically by 2D pose estimation algorithms and outputs the head pose represented by yaw, pitch, and roll. Our model is simple to implement and more efficient with respect to the state of the art -- faster in inference and smaller in terms of memory occupancy -- with comparable accuracy. Our method also provides a measure of the heteroscedastic uncertainties associated with the three angles, through an appropriately designed loss function; we show there is a correlation between error and uncertainty values, thus this extra source of information may be used in subsequent computational steps. As an example application, we address social interaction analysis in images: we propose an algorithm for a quantitative estimation of the level of interaction between people, starting from their head poses and reasoning on their mutual positions. The code is available at https://github.com/cantarinigiorgio/HHP-Net.
We explore electron pre-acceleration at high Mach-number nonrelativistic perpendicular shocks at, e.g., young supernova remnants, which are a prerequisite of further acceleration to very high energies via diffusive shock acceleration. Using fully kinetic particle-in-cell simulations of shocks and electron dynamics in them, we investigate the influence of shock-surfing acceleration at the shock foot on the nonthermal population of electrons downstream of the shock. The shock-surfing acceleration is followed by further energization at the shock ramp where the Weibel instability spawns a type of second-order Fermi acceleration. The combination of these two processes leads to the formation of a nonthermal electron population, but the importance of shock-surfing acceleration becomes smaller for larger ion-to-electron mass ratio in the simulation. We discuss the resulting electron spectra and the relevance of our results to the physics of systems with real ion-to-electron mass ratio and fully three-dimensional behavior.
In this paper we present a new chemical evolution model for the Galaxy which assumes two main infall episodes for the formation of halo-thick disk and thin disk, respectively. We do not try to take into account explicitly the evolution of the halo but we implicitly assume that the timescale for the formation of the halo was of the same order as the timescale for the formation of the thick disk. The formation of the thin-disk is much longer than that of the thick disk, implying that the infalling gas forming the thin-disk comes not only from the thick disk but mainly from the intergalactic medium. The timescale for the formation of the thin-disk is assumed to be a function of the galactocentric distance, leading to an inside-out picture for the Galaxy building. The model takes into account the most up to date nucleosynthesis prescriptions and adopts a threshold in the star formation process which naturally produces a hiatus in the star formation rate at the end of the thick disk phase, as suggested by recent observations. The model results are compared with an extended set of observational constraints. Among these constraints, the tightest one is the metallicity distribution of the G-dwarf stars for which new data are now available. Our model fits very well these new data. We show that in order to reproduce most of these constraints a timescale $\le 1$ Gyr for the (halo)-thick-disk and of 8 Gyr for the thin-disk formation in the solar vicinity are required. We predict that the radial abundance gradients in the inner regions of the disk ($R< R_{\odot}$) are steeper than in the outer regions, a result confirmed by recent abundance determinations, and that the inner ones steepen in time during the Galactic lifetime.
We consider the decays of a correlated neutral-meson--antimeson state with C-parity +1. We show that there is CPT noninvariance in the mixing of the neutral mesons if, for any two decay modes f and g, the decay rate has a component R_A which is antisymmetric under the interchange of the decay times t_1 and t_2. In particular, one may cleanly extract the CPT-noninvariance parameter with the help of R_A by using opposite-sign dilepton events.
We present the first detailed three-dimensional hydrodynamic implicit large eddy simulations of turbulent convection for carbon burning. The simulations start with an initial radial profile mapped from a carbon burning shell within a 15 solar mass stellar evolution model. We considered 4 resolutions from 128^3 to 1024^3 zones. These simulations confirm that convective boundary mixing (CBM) occurs via turbulent entrainment as in the case of oxygen burning. The expansion of the boundary into the surrounding stable region and the entrainment rate are smaller at the bottom boundary because it is stiffer than the upper boundary. The results of this and similar studies call for improved CBM prescriptions in 1D stellar evolution models.
Motivated by the emergence of multicore architectures, and the reality that parallelism is rarely used for analysis in observational astronomy, we demonstrate how general users may employ tightly-coupled multiprocessors in scriptable research calculations while requiring no special knowledge of parallel programming. Our method rests on the observation that much of the appeal of high-level vectorized languages like IDL or MatLab stems from relatively simple internal loops over regular array structures, and that these loops are highly amenable to automatic parallelization with OpenMP. We discuss how ISIS, an open-source astrophysical analysis system embedding the S-Lang numerical language, was easily adapted to exploit this pattern. Drawing from a common astrophysical problem, model fitting, we present beneficial speedups for several machine and compiler configurations. These results complement our previous efforts with PVM, and together lead us to believe that ISIS is the only general purpose spectroscopy system in which such a range of parallelism -- from single processors on multiple machines to multiple processors on single machines -- has been demonstrated.
In this paper, we introduce a new concept namely degree polynomial for vertices of a simple graph. This notion leads to a concept namely degree polynomial sequence which is stronger than the concept of degree sequence. After obtaining the degree polynomial sequence for some well-known graphs, we prove a theorem which gives a necessary condition for realizability of a sequence of polynomials with coefficients in positive integers. Also we calculate the degree polynomial for vertises of join, Cartesian product, tensor product, and lexicographic product of two simple graphs and for vertices of the complement of a simple graph. Some examples, counterexamples, and open problems concerning to this subjects, is given as well
We use our former results on pi+pi- S-wave obtained in a nearly assumption-free way from the 17.2 GeV/c data to predict the pi0pi0 S--wave. The predictions are compared with the recent results of the E852 experiment at 18.3 GeV/c. A good agreement is found for only one (the "down-flat") solution while the second one (the "up-flat") is excluded by the pi0pi0 data. Thus the long-standing "up-down" ambiguity has been finally resolved in favour of the S-wave intensity which stays large and nearly constant up to the KK-bar threshold. A joint analysis of both sets of data leads to a reduction of errors for this solution.
We calculate the spin dependent static force between two D0-branes in Matrix theory. Supersymmetry relates velocity dependent potentials to spin dependent potentials. The well known v^4/r^7 term is related to a theta^8/r^11 term, where theta is the relative spin of the D0-branes. We calculate this term, confirming that it is the lowest order contribution to the static potential, and find its structure consistent with supergravity.
In this paper we introduce a new camera localization strategy designed for image sequences captured in challenging industrial situations such as industrial parts inspection. To deal with peculiar appearances that hurt standard 3D reconstruction pipeline, we exploit pre-knowledge of the scene by selecting key frames in the sequence (called as anchors) which are roughly connected to a certain location. Our method then seek the location of each frame in time-order, while recursively updating an augmented 3D model which can provide current camera location and surrounding 3D structure. In an experiment on a practical industrial situation, our method can localize over 99% frames in the input sequence, whereas standard localization methods fail to reconstruct a complete camera trajectory.
We study the Stephani quantum cosmological model in the presence of a cosmological constant in radiation dominated Universe. In the present work the Schutz's variational formalism which recovers the notion of time is applied. This gives rise to Wheeler-DeWitt equations which can be cast in the form of Schr\"odinger equations for the scale factor. We find their eigenvalues and eigenfunctions by using the Spectral Method. Then we use the eigenfunctions in order to construct wave packets and evaluate the time-dependent expectation value of the scale factor, which is found to oscillate between non-zero finite maximum and minimum values. Since the expectation value of the scale factor never tends to the singular point, we have an initial indication that this model may not have singularities at the quantum level.
The extreme statistics of time signals is studied when the maximum is measured from the initial value. In the case of independent, identically distributed (iid) variables, we classify the limiting distribution of the maximum according to the properties of the parent distribution from which the variables are drawn. Then we turn to correlated periodic Gaussian signals with a 1/f^alpha power spectrum and study the distribution of the maximum relative height with respect to the initial height (MRH_I). The exact MRH_I distribution is derived for alpha=0 (iid variables), alpha=2 (random walk), alpha=4 (random acceleration), and alpha=infinity (single sinusoidal mode). For other, intermediate values of alpha, the distribution is determined from simulations. We find that the MRH_I distribution is markedly different from the previously studied distribution of the maximum height relative to the average height for all alpha. The two main distinguishing features of the MRH_I distribution are the much larger weight for small relative heights and the divergence at zero height for alpha>3. We also demonstrate that the boundary conditions affect the shape of the distribution by presenting exact results for some non-periodic boundary conditions. Finally, we show that, for signals arising from time-translationally invariant distributions, the density of near extreme states is the same as the MRH_I distribution. This is used in developing a scaling theory for the threshold singularities of the two distributions.
We present an optical/near-infrared search for a counterpart to the perplexing radio transient GCRT J1745-3009, a source located ~1 degree from the Galactic Center. Motivated by some similarities to radio bursts from nearby ultracool dwarfs, and by a distance upper limit of 70 pc for the emission to not violate the 1e12 K brightness temperature limit for incoherent radiation, we searched for a nearby star at the position of GCRT J1745-3009. We found only a single marginal candidate, limiting the presence of any late-type star to >1 kpc (spectral types earlier than M9), >200 pc (spectral types L and T0-T4), and >100 pc (spectral types T4-T7), thus severely restricting the possible local counterparts to GCRT J1745-3009. We also exclude any white dwarf within 1 kpc or a supergiant star out to the distance of the Galactic Center as possible counterparts. This implies that GCRT J1745-3009 likely requires a coherent emission process, although whether or not it reflects a new class of sources is unclear.
Ground state properties of proton-rich odd-$Z$ nuclei in the region $55\le Z \le 73$ are studied in the relativistic mean field (RMF) theory. The RMF equations are solved by using the expansion method in the Harmonic-Oscillator basis. In the particle-particle channel, we use the state-dependent BCS method with a zero-range $\delta$-force, which has been proved to be effective even for neutron-rich nuclei. All the ground state properties, including the one-proton separation energies, the ground state deformations, the last occupied proton orbits and the locations of proton drip line, are calculated. Good agreement with both the available experimental data and the predictions of the RHB method are obtained.
The process of pair creation by a photon in a constant and homogeneous electromagnetic field of an arbitrary configuration is investigating. At high energy the correction to the standard quasiclassical approximation (SQA) has been calculated. In the region of intermediate photon energies where SQA is inapplicable the new approximation, developed recently by authors, is used. The influence of weak electric field on the process in a magnetic field is considered. In particular, in the presence of electric field the root divergence in the probability of pair creation on the Landau energy levels is vanished. For smaller photon energies the low energy approximation is used. The found probability describes the absorption of soft photon by particles created by field. At low photon energy the electric field action dominates and the influence of magnetic field on the process is connected with the interaction of it and the magnetic moment of creating particles.
Zeckendorf proved that every positive integer can be written uniquely as the sum of non-adjacent Fibonacci numbers. We further explore a two-player Zeckendorf game introduced in Baird-Smith, Epstein, Flint, and Miller: Given a fixed integer $n$ and an initial decomposition of $n = nF_1$, players alternate using moves related to the recurrence relation $F_{n+1} = F_n + F_{n_1}$, and the last player to move wins. We improve the upper bound on the number of moves possible and show that it is of the same order in $n$ as the lower bound; this is an improvement by a logarithm over previous work. The new upper bound is $3n - 3Z(n) - IZ(n) + 1$, and the existing lower bound is sharp at $n - Z(n)$ moves, where $Z(n)$ is the number of terms in the Zeckendorf decomposition of $n$ and $IZ(n)$ is the sum of indices in the same Zeckendorf decomposition of $n$. We also studied four deterministic variants of the game, where there was a fixed order on which available move one takes: Combine Largest, Split Largest, Combine Smallest and Split Smallest. We prove that Combine Largest and Split Largest realize the lower bound. Split Smallest has the largest number of moves over all possible games, and is close to the new upper bound. For Combine Split games, the number of moves grows linearly with $n$.
The ferromagnetic (FM) nature of the metallic LaCo$_2$P$_2$ was investigated with the positive muon spin rotation, relaxation and resonance ($\mu^+$SR) technique. Transverse and zero field $\mu^+$SR measurements revealed that the compound enters a long range FM ground state at $T_{\rm C}=130.91(65)$~K, consistent with previous studies. Based on the reported FM structure, the internal magnetic field was computed at the muon sites, which were predicted with first principles calculations. The computed result agree well with the experimental data. Moreover, although LaCo$_2$P$_2$ is a paramagnet at higher temperatures $T>160$~K, it enters a short range ordered (SRO) magnetic phase for $T_{\rm C}<T\leq160$~K. Measurements below the vicinity of $T_{\rm C}$ revealed that the SRO phase co-exists with the long range FM order at temperatures $124\leq T\leq T_{\rm C}$. Such co-existence is an intrinsic property and stems from competition between the 2D and 3D interactions/fluctuations.
We discuss the generation and monitoring of durable atomic entangled state via Raman-type process, which can be used in the quantum information processing.
Using images from the Hubble Space Telescope Wide-Field Camera 3, we measure the rate of diffusion of stars through the core of the globular cluster 47 Tucanae using a sample of young white dwarfs identified in these observations. This is the first direct measurement of diffusion due to gravitational relaxation. We find that the diffusion rate $\kappa\approx 10-13$ arcsecond$^2$ Myr$^{-1}$ is consistent with theoretical estimates of the relaxation time in the core of 47 Tucanae of about 70 Myr.
We discuss the difficulties in testing the hadron models by using the N^* parameters extracted from the empirical amplitude analyses of the pi-N and gamma-N reaction data. As an alternative or perhaps a more advantageous approach, we present a Hamiltonian formulation that can relate the pion production dynamics and the constituent quark models of N^* structure. The application of the approach in investigating the Delta and N^*(S_{11}) excitations is reviewed. It is found that while the Delta excitation can be described satisfactory, the pi-N scattering in S_{11} channel can not be described by the constituent quark models based on either the one-gluon-exchange or one-meson-exchange mechanisms. A phenomenological quark-quark potential has been constructed to reproduce the S_{11} amplitude.
In this note, we speculate about the fundamental role being played by the $SO(8)$ group representations displaying the triality structure that necessarily arise in models constructed under the free fermionic methodology as being remnants of the higher-dimensional triality algebra tri$(\mathbb{O}) = \mathfrak{so}(8)$.
In this paper, we investigate some properties of the Perron vector of connected graphs. These results are used to characterize that all extremal connected graphs with having the minimum (maximum) spectra radius among all connected graphs of order $n=k\alpha$ with the independence number $\alpha$, respectively.
We explore the physics of shock evolution and particle acceleration in non-relativistic collisionless shocks using multidimensional hybrid simulations. We analyze a wide range of physical parameters relevant to the acceleration of cosmic rays (CRs) in astrophysical non-relativistic shock scenarios, such as in supernova remnant (SNR) shocks. We explore the evolution of the shock structure and particle acceleration efficiency as a function of Alfv\'enic Mach number and magnetic field inclination angle $\theta$. We show that there are fundamental differences between high and low Mach number shocks in terms of the electromagnetic turbulence generated in the pre-shock zone and downstream; dominant modes are resonant with the streaming CRs in the low Mach number regime, while both resonant and non-resonant modes are present for high Mach numbers. Energetic power law tails for ions in the downstream plasma can account for up to 15% of the incoming upstream flow energy, distributed over $\sim5%$ of the particles in a power law with slope $-2\pm0.2$ in energy. The energy conversion efficiency (for CRs) peaks at $\theta=15^\circ$ to $30^\circ$ and $M_A=6$, and decreases for higher Mach numbers, down to $\sim2%$ for $M_A=31$. Accelerated particles are produced by Diffusive Shock Acceleration (DSA) and by Shock Drift Acceleration (SDA) mechanisms, with the SDA contribution to the overall energy gain increasing with magnetic inclination. We also present a direct comparison between hybrid and fully kinetic particle-in-cell results at early times; the agreement between the two models justifies the use of hybrid simulations for longer-term shock evolution. In SNR shocks, particle acceleration will be significant for low Mach number quasi-parallel flows ($M_A < 30$, $\theta< 45$). This finding underscores the need for effective magnetic amplification mechanism in SNR shocks.