ShantanuT01/DACTYL-Pretraining huggingface dataset:
In this paper, we address semantic segmentation of road-objects from 3D LiDAR point clouds. In particular, we wish to detect and categorize instances of interest, such as cars, pedestrians and cyclists. We formulate this problem as a point- wise classification problem, and propose an end-to-end pipeline called SqueezeSeg based on convolutional neural networks (CNN): the CNN takes a transformed LiDAR point cloud as input and directly outputs a point-wise label map, which is then refined by a conditional random field (CRF) implemented as a recurrent layer. Instance-level labels are then obtained by conventional clustering algorithms. Our CNN model is trained on LiDAR point clouds from the KITTI dataset, and our point-wise segmentation labels are derived from 3D bounding boxes from KITTI. To obtain extra training data, we built a LiDAR simulator into Grand Theft Auto V (GTA-V), a popular video game, to synthesize large amounts of realistic training data. Our experiments show that SqueezeSeg achieves high accuracy with astonishingly fast and stable runtime (8.7 ms per frame), highly desirable for autonomous driving applications. Furthermore, additionally training on synthesized data boosts validation accuracy on real-world data. Our source code and synthesized data will be open-sourced.
Thorne elucidated that the relativistic tidal heating is the same as the Newtonian theory. Moreover, Thorne also claimed that the tidal heating is independent of how one localizes gravitational energy and is unambiguously given by a certain formula. Purdue and Favata calculated the tidal heating for different classical pseudotensors including Moller and obtained the results all matched with the Newtonian perspective. After re-examined this Moller pseudotensor, we find that there does not exist any tidal heating value. Thus we claim that the relativistic tidal heating is pseudotensor independent under the condition that if the peusdotensor is a Freud typed superpotential.
We show that any toric Fano manifold of dimension at most eight with the positive second Chern character is isomorphic to the projective space by using polymake.
We classify nontrivial, nonnegative, positively homogeneous solutions of the equation \begin{equation*} \Delta u=\gamma u^{\gamma-1} \end{equation*} in the plane.   The problem is motivated by the analysis of the classical Alt-Phillips free boundary problem, but considered here with negative exponents $\gamma$.   The proof relies on several bespoke results for ordinary differential equations.
We examine the evolution of intragroup gas X-ray scaling relations for group-sized halos ($M_{500}=10^{12.3-15}M_{\odot}$) in the Simba galaxy formation simulation. X-ray luminosity $L_X$ vs $M_{500}$ shows increasing deviation from self-similarity from $z=3\to 0$, with $M_{500}<10^{13.5} M_{\odot}$ halos exhibiting a large reduction in $L_X$ and slight increase in X-ray luminosity-weighted temperature $T_X$. These shifts are driven by a strong drop in $f_{\rm gas}$ with time for these halos, and coincides with the onset of black hole jet feedback in these systems at $z\sim 1.5$ in Simba. The connection with black hole feedback is corroborated by $f_{BH}\equiv M_{BH}/M_{500}$ in $M_{500}<10^{13.5} M_{\odot}$ halos being strongly anti-correlated with $L_X$ and $f_{\rm gas}$ at $z\la 1.5$. This is further reflected in the scatter of $L_X-T_X$: halos with small $f_{BH}$ lie near self-similarity, while those with the highest $f_{BH}$ lie furthest below. Turning off jet feedback results in mostly self-similar behaviour down to $z=0$. For the X-ray weighted metallicity $Z_X$, stellar feedback impacts the enrichment of halo gas. Finally, halo profiles show that jet feedback flattens the electron density and entropy profiles, and introduces a core in X-ray surface brightness particularly at $M_{500}<10^{13.5} M_{\odot}$. This argues that intragroup X-ray evolution is largely driven by jet feedback removing hot gas from the cores of massive groups, and expelling gas altogether in less massive groups.
Two of the most important and pressing questions in cosmology and particle physics are: (1) What is the nature of cold dark matter? and (2) Will near-future experiments on neutrinoless double beta decay be able to ascertain that the neutrino is a Majorana particle, i.e. its own antiparticle? We show that these two seemingly unrelated issues are intimately connected if neutrinos acquire mass only because of their interactions with dark matter.
Energies of the ground, $\beta$ and $\gamma$ bands as well as the associated B(E2) values are determined for each even-even isotope of the $^{180-196}$Pt chain by the exact solutions of some differential equations which approximate the generalized Bohr-Mottelson Hamiltonian. The emerging approaches are called the Sextic and Spheroidal Approach (SSA), the Sextic and Mathieu Approach (SMA), the Infinite Square Well and Spheroidal Approach (ISWSA) and the Infinite Square Well and Mathieu Approach (ISWMA), respectively. While the first three methods were formulated in some earlier papers of the present authors, ISWMA is an inedited approach of this work. Numerical results are compared with those obtained with the so called X(5) and Z(5) models. A contour plot for the probability density as function of the intrinsic dynamic deformations is given for a few states of the three considered bands with the aim of evidencing the shape evolution along the isotope chain and pointing out possible shape coexistence.
We examine the soft supersymmetry breaking parameters in supersymmetric theories on a slice of AdS_5 which generate the hierarchical Yukawa couplings by dynamically localizing the bulk matter fields in extra dimension. Such models can be regarded as the AdS dual of the recently studied 4-dimensional models which contain a supersymmetric CFT to generate the hierarchical Yukawa couplings. In such models, if supersymmetry breaking is mediated by the bulk radion superfield and/or some brane chiral superfields, potentially dangerous flavor-violating soft parameters can be naturally suppressed, thereby avoiding the SUSY flavor problem. We present some models of radion-dominated supersymmetry breaking which yield a highly predictive form of soft parameters in this framework.
Ni-Mn based ternary Heusler compounds have drawn attentions lately as significant magneto-caloric effects in some of them have been observed. Substitution of Ni and Mn by other $3d$ transition metals in controlled quantity have turned out to be successful in enhancing the effect and bring the operational temperatures closer to the room temperature. Using density functional theory calculations, in this work, we have systematically explored the roles of various factors such as site occupancies, magnetic interactions, and compositions associated with the constituents of Mn-excess Ni$_{2}$MnSb Heusler compounds upon substitution of Ni and/or Mn by $3d$ transition metals Fe, Co and Cu. Our calculations unveiled the physics behind the variations of physical properties associated with the magneto-caloric effects, and thus interpreted the available experimental results successfully. The work also provided important information on the compounds and the composition ranges where significant magneto-caloric effects may be realised and further experimental investigations need to be done.
We briefly describe some well-known means and their properties, focusing on the relationship with integer sequences. In particular, the harmonic numbers, deriving from the harmonic mean, motivate the definition of a new kind of mean that we call the biharmonic mean. The biharmonic mean allows to introduce the biharmonic numbers, providing a new characterization for primes. Moreover, we highlight some interesting divisibility properties and we characterize the semi--prime biharmonic numbers showing their relationship with linear recurrent sequences that solve certain Diophantine equations.
We report on 12 years of observations of PSR J1713+0747, a pulsar in a 68-day orbit with a white dwarf. Pulse times of arrival were measured with uncertainties as small as 200 ns. The timing data yielded measurements of the relativistic Shapiro delay, perturbations of pulsar orbital elements due to secular and annual motion of the Earth, and the pulsar's parallax, as well as pulse spin-down, astrometric, and Keplerian measurements. The observations constrain the masses of the pulsar and secondary star to be m1=1.3+-0.2 solar masses and m2=0.28+-0.03 solar masses, respectively (68% confidence). Combining the theoretical orbital period-core mass relation with the observational constraints yields a somewhat higher pulsar mass, m1=1.53-0.06+0.08 solar masses. The parallax is 0.89+-0.08 mas, corresponding to a distance of 1.1+-0.1 kpc; the precision of the parallax measurement is limited by uncertainties in the electron content of the solar wind. The transverse velocity is unusually small, 33+-3 km/s. We find significant timing noise on time scales of several years, but no more than expected by extrapolating timing noise statistics from the slow pulsar population. With the orientation of the binary orbit fully measured, we are able to improve on previous tests of equivalence principle violations.
We obtained a simple theoretical unified parameter for the characterization of rotational population propagation of diatomic molecules in a periodic train of resonant optical pulses. The parameter comprises the peak intensity and interval between the pulses, and the level energies of the initial and final rotational states of the molecule. Using the unified parameter, we can predict the upper and lower boundaries of probability localization on the rotational level network, including the effect of centrifugal distortion. The unified parameter was tentatively derived from an analytical expression obtained by performing rotating-wave approximation and spectral decomposition of the time-dependent Schr\"{o}dinger equation under an assumption of time-order invariance. The validity of the parameter was confirmed by comparison with numerical simulations for isotope-selective rotational excitation of KCl molecules.
Recently, States of Low Energy (SLEs) have been proposed as viable vacuum states of primordial perturbations within Loop Quantum Cosmology (LQC). In this work we investigate the effect of the high curvature region of LQC on the definition of SLEs. Shifting the support of the test function that defines them away from this regime results in primordial power spectra of perturbations closer to those of the so-called Non-oscillatory (NO) vacuum, which is another viable choice of initial conditions previously introduced in the LQC context. Furthermore, through a comparison with the Hadamard-like SLEs, we prove that the NO vacuum is of Hadamard type as well.
We develop a microscopic theory for the charge ordering (CO) transitions in the spinels AlV$_2$O$_4$ and LiV$_2$O$_4$ (under pressure). The high degeneracy of CO states is lifted by a coupling to the rhombohedral lattice deformations which favors transition to a CO state with inequivalent V(1) and V(2) sites forming Kagom\'e and trigonal planes respectively. We construct an extended Hubbard type model including a deformation potential which is treated in unrestricted Hartree Fock approximation and describes correctly the observed first-order CO transition. We also discuss the influence of associated orbital order. Furthermore we suggest that due to different band fillings AlV$_2$O$_4$ should remain metallic while LiV$_2$O$_4$ under pressure should become a semiconductor when charge disproportionation sets in.
In this paper we study ensembles of random symmetric matrices $\X_n = {X_{ij}}_{i,j = 1}^n$ with dependent entries such that $\E X_{ij} = 0$, $\E X_{ij}^2 = \sigma_{ij}^2$, where $\sigma_{ij}$ may be different numbers. Assuming that the average of the normalized sums of variances in each row converges to one and Lindeberg condition holds we prove that the empirical spectral distribution of eigenvalues converges to Wigner's semicircle law.
We present new optical, near infrared, and archival ultraviolet observations of XX Ophiuchi and AS 325, two proposed iron stars. These unusual stars have optical spectra dominated by emission lines arising from hydrogen as well as ionized metals such as iron, chromium, and titanium. Both stars have been classified as iron stars and a number of exotic models have been presented for their origin. Using two years of moderately high resolution optical spectroscopy, the first high signal-to-noise K-band spectroscopy of these sources (which reveals stellar photospheric absorption lines), and new near-infrared interferometric observations, we confirm that both systems are composed of two stars, likely binaries, containing a hot Be star with an evolved late-type secondary. The hydrogen emission features arise in the hot wind from the Be star while the corresponding P-Cygni absorption lines are produced from dense material in the expanding, radiation driven, wind around each system. The optical FeII emission lines are pumped by ultraviolet FeII absorption lines through fluorescence. Contrary to some claims in the literature, the spectral features of XX Oph and AS 325 are quite similar, evidence that they are comparable systems. We examine the variability of the spectral morphology and radial velocity motions of both sources. We also study the variability of XX Oph during a major photometric event and find that the spectral nature of the system varies during the event. A comparison of the velocity of the absorption line components in our new spectra with those in the literature show that the structure of the stellar wind from XX Oph has changed since the system was observed in 1951.
The reaction $pp \to pp2\gamma$, proposed earlier to probe for the NN--decoupled dibaryon resonances, has been studied by the DIB$2\gamma$ Collaboration (JINR) and their preliminary data seem to give evidence for the resonance effect at about 1920 MeV. We discuss some other two-photon processes: the double radiative capture reaction in pionic deuterium, photoabsorption sum rules and the nuclear Compton scattering, which we consider to be especially feasible for further test and invesigation of possible low-lying, exotic six-quark states.
Topologically protected fermionic quasiparticles appear in metals, where band degeneracies occur at the Fermi level, dictated by the band structure topology. While in some metals these quasiparticles are direct analogues of elementary fermionic particles of the relativistic quantum field theory, other metals can have symmetries that give rise to quasiparticles, fundamentally different from those known in high-energy physics. Here we report on a new type of topological quasiparticles -- triple point fermions -- realized in metals with symmorphic crystal structure, which host crossings of three bands in the vicinity of the Fermi level protected by point group symmetries. We find two topologically different types of triple point fermions, both distinct from any other topological quasiparticles reported to date. We provide examples of existing materials that host triple point fermions of both types, and discuss a variety of physical phenomena associated with these quasiparticles, such as the occurrence of topological surface Fermi arcs, transport anomalies and topological Lifshitz transitions.
Axions or more generally axion-like particles (ALPs) are pseudo-scalar particles predicted by many extensions of the Standard Model of particle physics (SM) and considered as viable candidates for dark matter (DM) in the universe. If they really exist in nature, they are expected to couple with photons in the presence of an external electromagnetic field through a form of the Primakoff effect. In addition, many string theory models of the early universe motivate the existence of a homogeneous Cosmic ALP Background (CAB) with 0.1-1 keV energies analogous to the Cosmic Microwave Background (CMB), arising via the decay of string theory moduli in the very early universe. The coupling between the CAB ALPs traveling in cosmic magnetic fields and photons allows ALPs to oscillate into photons and vice versa. In this work, we test the CAB model that is put forward to explain the soft X-ray excess in the Coma cluster due to CAB ALPs conversion into photons using the M87 jet environment. Then we demonstrate the potential of the active galactic nuclei (AGNs) jet environment to probe low-mass ALP models, and to potentially constrain the model proposed to better explain the Coma cluster soft X-ray excess. We find that the overall X-ray emission for the M87 AGN requires an ALP-photon coupling $g_{a\gamma}$ in the range of $\sim7.50\times 10^{-15}-6.56\times 10^{-14}$ GeV$^{-1}$ for ALP masses $m_a \lesssim 10^{-13}$ eV as long as the M87 jet is misaligned by less than about 20 degrees from the line of sight. These values are up to an order of magnitude smaller than the current best fit value on $g_{a\gamma}\sim 2\times 10^{-13}$ GeV$^{-1}$ obtained in soft X-ray excess CAB model for the Coma cluster. Our results cast doubt on the current limits of the largest allowed value of $g_{a\gamma}$ and suggest a new constraint that $g_{a\gamma}\lesssim 6.56\times 10^{-14}$ GeV$^{-1}$ when a CAB is assumed.
We employ mean value estimates of Weyl sums in order to obtain discrete second moments of the Riemann Zeta-function with respect to polynomials near the vertical line $1+i\mathbb{R}$.
We present and discuss the stellar kinematics and populations of the S0 galaxy FCC 170 (NGC 1381) in the Fornax cluster, using deep MUSE data from the Fornax 3D survey. We show the maps of the first four moments of the stellar line-of-sight velocity distribution and of the mass-weighted mean stellar age, metallicity and [Mg/Fe] abundance ratio. The high-quality MUSE stellar kinematic measurements unveil the structure of this massive galaxy: a nuclear disk, a bar seen as a boxy bulge with a clear higher-velocity-dispersion X shape, a fast-rotating and flaring thin disk and a slower rotating thick disk. Whereas their overall old age makes it difficult to discuss differences in the formation epoch between these components, we find a clear-cut distinction between metal-rich and less [Mg/Fe]-enhanced populations in the thin-disk, boxy-bulge and nuclear disk, and more metal-poor and [Mg/Fe]-enhanced stars in the thick disk. Located in the densest region of the Fornax cluster, where signs of tidal stripping have been recently found, the evolution of FCC 170 might have been seriously affected by its environment. We discuss the possibility of its "pre-processing" in a subgroup before falling into the present-day cluster, which would have shaped this galaxy a long time ago. The thick disk displays a composite star formation history, as a significant fraction of younger stars co-exist with the main older thick-disk population. The former sub-population is characterized by even lower-metallicity and higher-[Mg/Fe] values, suggesting that these stars formed later and faster in a less chemically evolved satellite, which was subsequently accreted. Finally, we discuss evidence that metal-rich and less [Mg/Fe]-enhanced stars were brought in the outer parts of the thick disk by the flaring of the thin disk.
We test a Yukawa correction to the Newtonian potential, making use of our own Galaxy - the Milky Way - as a testbed. We include as free parameter the Yukawa strength and range and the dark matter profile parameters, and compare several morphologies for the bulge, gas, and disk components, also using Bayesian model selection criteria. We employ up-to-date datasets for both the visible (baryonic) component of the Milky Way, and for the tracers of the gravitational potential (the Rotation Curve). We find that the data are consistent with the Newtonian potential, and constrain the Yukawa coupling $\beta$ to be negative and $\lambda$ to range along the curve $\lambda = a|\beta|^{c}$ with $a = (0.77 \pm 0.06)$ kpc and $c = -0.503\substack{+0.016 \\ -0.019}$.
We study magnetic and critical properties of the alternating spin antiferromagnetic Heisenberg chain with $S=1/2$ and 1 in a magnetic field at T=0. The numerical diagonalization is applied to the system up to $2N=20$ sites. Checking numerically that magnetic states with the magnetization per site $m$ obey a conformal field theory with conformal anomaly $c=1$ for $1/4<m<3/4$, we use the finite-size scaling of the conformal invariance to obtain a magentization curve in the thermodynamic limit. In the magnetizatin curve a plateau appears at $m=1/4$. We also calculate two critical exponents $\eta$ and $\eta^z$ for $1/4<m<3/4$, which control the asymptotic behavior of the transverse and parallel spin correlation functions. We check the relation $\eta \eta^z=1$, which universally holds for a $c=1$ conformal field theory.
The spherical Fourier-Bessel (SFB) decomposition is a natural choice for the radial/angular separation that allows extraction of cosmological information from large volume galaxy surveys, taking into account all wide-angle effects. In this paper we develop a SFB power spectrum estimator that allows the measurement of the largest angular and radial modes with the next generation of galaxy surveys. The code measures the pseudo-SFB power spectrum, and takes into account mask, selection function, pixel window, and shot noise. We show that the local average effect (or integral constraint) is significant only in the largest-scale mode, and we provide an analytical covariance matrix. By imposing boundary conditions at the minimum and maximum radius encompassing the survey volume, the estimator does not suffer from the numerical instabilities that have proven challenging for SFB analyses in the past. The estimator is demonstrated on simplified but realistic Roman-like, SPHEREx-like, and Euclid-like mask and selection functions. For intuition and validation, we also explore the SFB power spectrum in the Limber approximation. We release the associated public code written in Julia.
The main technique used to edge-colour graphs requiring $\Delta+2$ or more colours is the method of Tashkinov trees. We present a specific limit to this method, in terms of Kempe changes. We also provide a new Tashkinov tree extension.
We study the effect of spin-Peierls instability on the phase-diagram of a frustrated antiferromagnetic spin-1/2 ladder, with weak transverse and diagonal rung coupling. Our analysis focuses on a one-dimensional version of the model (i.e. a single two-leg ladder) where we consider two forms of spin-Peierls (SP) instabilities on the legs: columnar dimers (CD) and staggered dimers (SD). We particularly examine the regime of parameters (corresponding to an intermediate XXZ anisotropy) where the SP and rung coupling terms are equally relevant. In both the CD and SD cases we find that the effective field theory describing the system is a self-dual sine-Gordon model, which favors ordering and the opening of a gap to excitations. The order parameter, which reflects the interplay between the SP and rung interactions, represents a crystal of 4-spin plaquettes on which longitudinal and transverse dimers are in a superposition. Depending on the SP instability mode these plaquettes are closed or open, however both types spontaneously break reflection symmetry across the ladder. The closed plaquettes are stable, while the open plaquette-order is relatively fragile and the corresponding gap may be tuned to zero under extreme conditions. We further find that a first order transition occurs from the Plaquette order to a valence bond crystal (VBC) of dimers on the legs. It is suggestive that in a higher dimensional version of this system, this variety of distinct VBC states with comparable energies leads to the formation of domains. Effectively one-dimensional gapless spinon modes on domain boundaries can possibly account for the experimental observation of a spin-liquid behavior in a physical realization of the model.