ShantanuT01/DACTYL-Pretraining huggingface dataset:
We propose a simple interpretation of the rotation period data for solar- and late-type stars. The open cluster and Mt. Wilson star observations suggest that rotating stars lie primarily on two sequences, initially called I and C. Some stars lie in the intervening gap. These sequences, and the fractional numbers of stars on each sequence evolve systematically with cluster age, enabling us to construct crude rotational isochrones allowing `stellar gyrochronology', a procedure, upon improvement, likely to yield ages for individual field stars. The age and color dependences of the sequences allow the identification of the underlying mechanism, which appears to be primarily magnetic. The majority of solar- and late-type stars possess a dominant Sun-like, or Interface magnetic field, which connects the convective envelope both to the radiative interior of the star and to the exterior where winds can drain off angular momentum. These stars spin down Skumanich-style. An age-decreasing fraction of young G, K, and M stars, which are rapid rotators, possess only a Convective field which is not only inefficient in depleting angular momentum, but also incapable of coupling the surface convection zone to the inner radiative zone, so that only the outer zone is spun down, and on an exponential timescale. These stars do not yet possess large-scale dynamos. The large-scale magnetic field associated with the dynamo, apparently created by the shear between the decoupled radiative and convective zones, (re)couples the convective and radiative zones and drives a star from the Convective to the Interface sequence through the gap on a timescale that increases as stellar mass decreases. (Abstract is truncated here.)
In 1960, the mathematician Ernst Specker described a simple example of nonclassical correlations which he dramatized using a parable about a seer who sets an impossible prediction task to his daughter's suitors. We revisit this example here, using it as an entree to three central concepts in quantum foundations: contextuality, Bell-nonlocality, and complementarity. Specifically, we show that Specker's parable offers a narrative thread that weaves together a large number of results, including: the impossibility of measurement-noncontextual and outcome-deterministic ontological models of quantum theory (the Kochen-Specker theorem), in particular the proof of Klyachko; the impossibility of Bell-local models of quantum theory (Bell's theorem), especially the proofs by Mermin and Hardy; the impossibility of a preparation-noncontextual ontological model of quantum theory; and the existence of triples of positive operator valued measures (POVMs) that can be measured jointly pairwise but not triplewise. Along the way, several novel results are presented, including: a generalization of a theorem by Fine connecting the existence of a joint distribution over outcomes of counterfactual measurements to the existence of a noncontextual model; a generalization of Klyachko's proof of the Kochen-Specker theorem; a proof of the Kochen-Specker theorem in the style of Hardy's proof of Bell's theorem; a categorization of contextual and Bell-nonlocal correlations in terms of frustrated networks; a new inequality testing preparation noncontextuality; and lastly, some results on the joint measurability of POVMs and the question of whether these can be modeled noncontextually. Finally, we emphasize that Specker's parable provides a novel type of foil to quantum theory, challenging us to explain why the particular sort of contextuality and complementarity embodied therein does not arise in a quantum world.
A consistent perturbation theory expansion is presented for phase-ordering kinetics in the case of a nonconserved scalar order parameter. At zeroth order in this expansion one obtains the theory due to Ohta, Jasnow and Kawasaki (OJK). At the next nontrivial order in the expansion, worked out in d dimensions, one has small corrections to the OJK result for the nonequilibrium exponent $\lambda$ and the introduction of a new exponent $\nu$ governing the algebraic component of the decay of the order parameter scaling function at large scaled distances.
The eccentricity (anti-adjacency) matrix $\varepsilon(G)$ of a graph $G$ is obtained from the distance matrix by retaining the eccentricities in each row and each column. This matrix is first defined in 2018 by Wang et al. \cite{1}. In this paper we have characterized the graphs which have at most one (hence exactly) positive eigenvalue of $\varepsilon(G)$.
We report results on the timing analysis of the 2020 giant outburst of 1A 0535+262, using broadband data from Insight-HXMT. The analysis of the pulse profile evolution from the sub-critical luminosity to super-critical luminosity regime is presented for the first time. We found that the observed pulse profile exhibits a complex dependence on both energy and luminosity.A dip structure at the energy of the cyclotron resonant scattering features (CRSFs) is found for the first time in the pulse fraction-energy relation of 1A 0535+262, when the outburst evolves in a luminosity range from 4.8 $\times 10^{37}$ erg s$^{-1}$ to 1.0 $\times 10^{38}$ erg s$^{-1}$. The observed structure is luminosity dependent and appears around the source critical luminosity ($\sim$ 6.7 $\times 10^{37}$ erg s$^{-1}$).
We re-analyse the ASCA and GINGA X-ray data from BY Cam, a slightly asynchronous magnetic accreting white dwarf. The spectra are strongly affected by complex absorption, which we model as a continuous (power law) distribution of covering fraction and column of neutral material. This absorption causes a smooth hardening of the spectrum below 3 keV, and is probably produced by material in the preshock column which overlies the X-ray emission region. The ASCA data show that the intrinsic emission from the shock is not consistent with a single temperature plasma. Significant iron L emission co-existing with iron K shell lines from H and He-like iron clearly shows that there is a wide range of temperatures present, as expected from a cooling shock structure. The GINGA data give the best constraints on the maximum temperature emission in the shocked plasma, with kT(max)=21(+18,-4) keV. Cyclotron cooling should also be important, which supresses the highest temperature bremsstrahlung components, so the X-ray data only give a lower limit on the mass of the white dwarf of M> 0.5 solar masses. Reflection of the multi-temperature bremsstrahlung emission from the white dwarf surface is also significantly detected.   We stress the importance of modelling ALL these effects in order to gain a physically self-consistent picture of the X-ray spectra from polars in general and BY Cam in particular.
The thermodynamics of the discrete nonlinear Schr\"odinger equation in the vicinity of infinite temperature is explicitly solved in the microcanonical ensemble by means of large-deviation techniques. A first-order phase transition between a thermalized phase and a condensed (localized) one occurs at the infinite-temperature line. Inequivalence between statistical ensembles characterizes the condensed phase, where the grand-canonical representation does not apply. The control over finite size corrections of the microcanonical partition function allows to design an experimental test of delocalized negative-temperature states in lattices of cold atoms.
We describe a method to reconstruct the conductivity and its normal derivative at the boundary from the knowledge of the potential and current measured at the boundary. This boundary determination implies the uniqueness of the conductivity in the bulk when it lies in $W^{1+\frac{n-5}{2p}+,p}$, for dimensions $n\ge 5$ and for $n\le p<\infty$.
Monatomic nanowires of the nonmagnetic transition metals Ru, Rh, and Pd have been studied theoretically, using first-principles computational techniques, in order to investigate the possible onset of magnetism in these nanosystems. Our fully relativistic spin-polarized all-electron density functional calculations reveal the onset of Hund's rule magnetism in nanowires of all three metals, with mean-field moments of 1.1, 0.3, and 0.7 bohr magnetons, respectively, at the equilibrium bond length. An analysis of the band structures indicates that the nanocontact superparamagnetic state suggested by our calculations should affect the ballistic conductance between tips made of Ru, Rh or Pd, leading to possible temperature and magnetic field dependent conductance.
Existing deep-learning based monocular orientation estimation algorithms faces the problem of confusion between the anterior and posterior parts of the objects, caused by the feature similarity of such parts in typical objects in traffic scenes such as cars and pedestrians. While difficult to solve, the problem may lead to serious orientation estimation errors, and pose threats to the upcoming decision making process of the ego vehicle, since the predicted tracks of objects may have directions opposite to ground truths. In this paper, we mitigate this problem by proposing a pretraining method. The method focuses on predicting the left/right semicircle in which the orientation of the object is located. The trained semicircle prediction model is then integrated into the orientation angle estimation model which predicts a value in range $[0, \pi]$. Experiment results show that the proposed semicircle prediction enhances the accuracy of orientation estimation, and mitigates the problem stated above. With the proposed method, a backbone achieves similar state-of-the-art orientation estimation performance to existing approaches with well-designed network structures.
On the base of the notion of N=2 abelian Yang-Mills supergeometry with constant curvature, we propose an off-shell formulation for the massive q-hypermultiplet and complex $\omega$-hypermultiplet in the standard harmonic superspase without central charge variables. The corresponding superpropagators are derived.
Nontrivial band topology combined with magnetic ordering can produce quantum anomalous Hall insulator (QAHI), which may lead to advances in device concepts. Here, through first-principles calculations, stable monolayer $\mathrm{Fe_2Br_2}$ is predicted as a room-temperature large-gap high-Chern-number QAHI by using generalized gradient approximation plus $U$ (GGA+$U$) approach. The large gap is due to correlation-enhanced spin-orbit coupling (SOC) effect of Fe atoms, which equates with artificially increasing the strength of SOC without electronic correlation. Out-of-plane magnetic anisotropy is very key to produce quantum anomalous Hall (QAH) state because in-plane magneitization will destroy nontrivial band topology. In the absence of SOC, $\mathrm{Fe_2Br_2}$ is a half Dirac semimetal state protected by mirror symmetry, and the electronic correlation along with SOC effect creates QAH state with a sizable gap and two chiral edge modes. It is found that the QAH state is robust against biaxial strain ($a/a_0$: 0.96 to 1.04) in monolayer $\mathrm{Fe_2Br_2}$ with stable ferromagnetic (FM) ordering and out-of-plane magnetic anisotropy. Calculated results show that Curie temperature is sensitive to correlation strength and strain. The reduced correlation and compressive strain are in favour of high Curie temperature. These analysis and results can be readily extended to other monolayer $\mathrm{Fe_2XY}$ (X/Y=Cl, Br and I), which possesses the same Fe-dominated low-energy states with a $\mathrm{Fe_2Br_2}$ monolayer. These findings open new opportunities to design new high-temperature topological quantum devices.
The correlations between a $B$ meson and a pion produced nearby in phase space should respect isospin reflection symmetry $I_3 \to -I_3$. Thus, one generally expects similar $\pi^+ B^0$ and $\pi^- B^+$ correlations (non-exotic channels), and similar $\pi^- B^0$ and $\pi^+ B^+$ correlations (exotic channels). Exceptions include (a) fragmentation processes involving exchange of quarks with the producing system, (b) misidentification of charged kaons as charged pions, and (c) effects of decay products of the associated $\overline{B}$. All of these can affect the apparent signal for correlations of charged $B$ mesons with charged hadrons. The identification of the flavor of neutral $B$ mesons through the decay $B^0 \to K^{*0} J/\psi$ requires good particle identification in order that the decay $K^{*0} \to K^+ \pi^-$ not be mistaken for $\overline{K}^{*0} \to K^- \pi^+$, in which case the correlations of neutral $B$ mesons with hadrons can be underestimated.
The Hamiltonian formulation of the Holst action in presence of a massless fermion field with a non-minimal Lagrangian is performed without any restriction on the local Lorentz frame. It is outlined that the phase space structure does not resemble that one of a background independent Lorentz gauge theory, as some additional constraints are present. Proper phase space coordinates are introduced, such that SU(2) connections can be defined and the vanishing of conjugate momenta to boost variables is predicted. Finally, it is demonstrated that for a particular value of the non-minimal parameter the kinematics coincides with that one of a background independent SU(2) gauge theory and the Immirzi parameter becomes the coupling constant of such an interaction between fermions and the gravitational field.
The discovery of very large piezo- and pyroelectric effects in ZrO2 and HfO2-based thin films opens up new opportunities to develop silicon-compatible sensor and actor devices. The effects are amplified close to the polar-orthorhombic to tetragonal phase transition temperature. Molecular dynamics is the preferred technique to simulate such effects, though its application has to solve the dilemma between sufficient accuracy and sufficient efficiency of the interatomic force field. Here we present a deep neural network-based interatomic force field of ZrO2 learned from ab initio data using a systematic learning procedure in the Deep Potential framework. The model potential is verified to predict a variety of structural and dynamic properties with an accuracy comparable to density functional theory calculations. Then the Deep Potential model is used to reproduce the different thermal expansion and piezo and pyroelectric phenomena in ZrO2 with molecular dynamics calculations. At low temperature simulating the direct effect we find negative values for the piezo-and pyroelectric coefficients matching the ab initio calculations. Approaching the phase transition temperature these values remain negative and become large. Simulating the field induced effect above the phase transition temperature we find positive, giant piezo-electric coefficients matching the observations. The model is able to explain the large values and the sign of the experimental observations in relation to the polar-orthorhombic to tetragonal phase transition. The model furthermore explains the recently observed giant dielectric constant in a similiar system.
In this work we study the inhomogeneous Muskat problem, \emph{i.e.} the evolution of an internal wave between two different fluids in a porous medium with discontinuous permeability. In particular, under precise conditions on the initial datum and the physical quantities of the problem, our results ensure the decay of the solutions towards the equilibrium state in the Lipschitz norm. In addition, we establish the global existence and decay of Lipschitz solutions.
In this paper, we consider a mathematical model for the evolution of neutral genetic diversity in a spatial continuum including mutations, genetic drift and either short range or long range dispersal. The model we consider is the spatial $ \Lambda $-Fleming-Viot process introduced by Barton, Etheridge and V\'eber, which describes the state of the population at any time by a measure on $ \R^d \times [0,1] $, where $ \R^d $ is the geographical space and $ [0,1] $ is the space of genetic types. In both cases (short range and long range dispersal), we prove a functional central limit theorem for the process as the population density becomes large and under some space-time rescaling. We then deduce from these two central limit theorems a formula for the asymptotic probability of identity of two individuals picked at random from two given spatial locations. In the case of short range dispersal, we recover the classical Wright-Mal\'ecot formula, which is widely used in demographic inference for spatially structured populations. In the case of long range dispersal we obtain a new formula which could open the way for a better appraisal of long range dispersal in inference methods.
Magnetic impurities embedded in a metal are screened by the Kondo effect, signaled by the formation of an extended correlation cloud, the so-called Kondo or screening cloud. In a superconductor, the Kondo state turns into sub-gap Yu-Shiba-Rusinov (Shiba) states, and a quantum phase transition occurs between screened and unscreened phases once the superconducting energy gap $\Delta$ becomes sufficiently large compared to the Kondo temperature, $T_K$. Here we show that, although the Kondo state does not form in the unscreened phase, the Kondo cloud does exist in both quantum phases. However, while screening is complete in the screened phase, it is only partial in the unscreened phase. Compensation, a quantity introduced to characterize the integrity of the cloud, is universal, and shown to be related to the magnetic impurities' $g$-factor, monitored experimentally by bias spectroscopy.
Several properties of high energy hadronic collisions are illustrated by comparing DIS and the Drell-Yan process within a scalar QED model. Diffraction and transverse momentum broadening within the target system are found to be non-universal. Here these effects are simply due to the Coulomb phase shift in the Drell-Yan production amplitude.
In this paper we propose a definition of a recurrence relation homomorphism and illustrate our definition with a few examples. We then define the period of a k-th order of linear recurrence relation and deduce certain preliminary results associated with them.
We present the widest-field resolved stellar map to date of the closest ($D\sim3.8$ Mpc) massive elliptical galaxy NGC 5128 (Centaurus A; Cen A), extending out to a projected galactocentric radius of $\sim150$ kpc. The dataset is part of our ongoing Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) utilizing the Magellan/Megacam imager. We resolve a population of old red giant branch stars down to $\sim1.5$ mag below the tip of the red giant branch, reaching surface brightness limits as low as $\mu_{V,0}\sim32$ mag arcsec$^{-2}$. The resulting spatial stellar density map highlights a plethora of previously unknown streams, shells, and satellites, including the first tidally disrupting dwarf around Cen A (CenA-MM-Dw3), which underline its active accretion history. We report 13 previously unknown dwarf satellite candidates, of which 9 are confirmed to be at the distance of Cen A (the remaining 4 are not resolved into stars), with magnitudes in the range $M_V=-7.2$ to $-13.0$, central surface brightness values of $\mu_{V,0}=25.4-26.9$ mag arcsec$^{-2}$, and half-light radii of $r_h=0.22-2.92$ kpc. These values are in line with Local Group dwarfs but also lie at the faint/diffuse end of their distribution; interestingly, CenA-MM-Dw3 has similar properties to the recently discovered ultra-diffuse galaxies in Virgo and Coma. Most of the new dwarfs are fainter than the previously known Cen A satellites. The newly discovered dwarfs and halo substructures are discussed in light of their stellar populations, and they are compared to those discovered by the PAndAS survey of M31.
We compute the low energy threshold corrections to neutrino masses and mixing in the Standard Model (SM) and its minimal supersymmetric version, using the effective theory technique. We demonstrate that they stabilize the renormalization group (RG) running with respect to the choice of the scale to which the RG equation is integrated. This confirms the correctness of the recent re-derivation of the RGE for the SM in hep-ph/0108005. The explicit formulae for the low energy threshold corrections corrections can be applied to specific models of neutrino masses and mixing.
We present a new code to evaluate thermoelectric and electronic transport properties of extended systems with a maximally-localized Wannier function basis set. The semiclassical Boltzmann transport equations for the homogeneous infinite system are solved in the constant relaxation-time approximation and band energies and band derivatives are obtained via Wannier interpolations. Thanks to the exponential localization of the Wannier functions obtained, very high accuracy in the Brillouin zone integrals can be achieved with very moderate computational costs. Moreover, the analytical expression for the band derivatives in the Wannier basis resolves any issues that may occur when evaluating derivatives near band crossings. The code is tested on binary and ternary skutterudites CoSb_3 and CoGe_{3/2}S_{3/2}.
Here we conjecture on a topological model based on the M\"obius strip derived from the current distribution at the plateaus of the Quantum Hall Effect (QHE). It can account for the fractional values of the QHE in an easy way.
Unknown class distributions in unlabelled astrophysical training data have previously been shown to detrimentally affect model performance due to dataset shift between training and validation sets. For radio galaxy classification, we demonstrate in this work that removing low angular extent sources from the unlabelled data before training produces qualitatively different training dynamics for a contrastive model. By applying the model on an unlabelled data-set with unknown class balance and sub-population distribution to generate a representation space of radio galaxies, we show that with an appropriate cut threshold we can find a representation with FRI/FRII class separation approaching that of a supervised baseline explicitly trained to separate radio galaxies into these two classes. Furthermore we show that an excessively conservative cut threshold blocks any increase in validation accuracy. We then use the learned representation for the downstream task of performing a similarity search on rare hybrid sources, finding that the contrastive model can reliably return semantically similar samples, with the added bonus of finding duplicates which remain after pre-processing.
We use more than two years of data from the Pierre Auger Observatory to search for anisotropies on large scales in different energy windows. We account for various systematics in the acceptance, in particular due to the array growth and weather variations. We present the results of analyses and consistency checks looking for patterns in the right ascension modulation of the cosmic ray distribution. No significant anisotropies of this kind are observed.
We construct an analytic model for the void-galaxy cross-correlation function that enables theoretical predictions of the dipole signal produced dominantly by the gravitational redshift within voids for the first time. By extending a theoretical formulation for the redshift-space distortion of galaxies to include the second order terms of the galaxy peculiar velocity $\bm v$ and the gravitational potential, we formulate the void-galaxy cross-correlation function multipoles in the redshift space, the monopole $\xi_0^{(s)}$, dipole $\xi_1^{(s)}$ and quadrupole $\xi_2^{(s)}$. We find that the dipole $\xi_1^{(s)}$ is dominated by the gravitational redshift, which provide a unique opportunity to detect the gravitational potential of voids. Thus, for the dipole $\xi_1^{(s)}(s)$, the gravitational redshift is crucial. Although the higher order effect is almost negligible on the monopole $\xi_0^{(s)}$, it has an influence on the quadrupole $\xi_2^{(s)}$. The effects from the random velocity of galaxies and the definition of the void center on the dipole signal are also discussed. Our model offers a new theoretical probe for the detection of gravitational redshift with voids and further tests on cosmology and gravity.