ShantanuT01/DACTYL-Pretraining huggingface dataset:
The studies on black-box adversarial attacks have become increasingly prevalent due to the intractable acquisition of the structural knowledge of deep neural networks (DNNs). However, the performance of emerging attacks is negatively impacted when fooling DNNs tailored for high-resolution images. One of the explanations is that these methods usually focus on attacking the entire image, regardless of its spatial semantic information, and thereby encounter the notorious curse of dimensionality. To this end, we propose a pixel correlation-based attentional black-box adversarial attack, termed as PICA. Firstly, we take only one of every two neighboring pixels in the salient region as the target by leveraging the attentional mechanism and pixel correlation of images, such that the dimension of the black-box attack reduces. After that, a general multiobjective evolutionary algorithm is employed to traverse the reduced pixels and generate perturbations that are imperceptible by the human vision. Extensive experimental results have verified the effectiveness of the proposed PICA on the ImageNet dataset. More importantly, PICA is computationally more efficient to generate high-resolution adversarial examples compared with the existing black-box attacks.
We consider new issues of duality in four-dimensional Lorentz-breaking field theories. In particular, we demonstrate that the arising of the aether-like Lorentz-breaking term is necessary in order for the 4D models to display the duality analog between the MCS and self-dual models in 3D. We further study the dispersion relations in both theories and discuss the physical contents of the models involved in this new dualilty.
Let $G$ be a connected graph. Given an ordered set $W = \{w_1, w_2,\dots w_k\}\subseteq V(G)$ and a vertex $u\in V(G)$, the representation of $u$ with respect to $W$ is the ordered $k$-tuple $(d(u,w_1), d(u,w_2),\dots,$ $d(u,w_k))$, where $d(u,w_i)$ denotes the distance between $u$ and $w_i$. The set $W$ is a metric generator for $G$ if every two different vertices of $G$ have distinct representations. A minimum cardinality metric generator is called a \emph{metric basis} of $G$ and its cardinality is called the \emph{metric dimension} of G. It is well known that the problem of finding the metric dimension of a graph is NP-Hard. In this paper we obtain closed formulae for the metric dimension of graphs with cut vertices. The main results are applied to specific constructions including rooted product graphs, corona product graphs, block graphs and chains of graphs.
We consider the isentropic Euler equations of gas dynamics in the whole two-dimensional space and we prove the existence of a $C^\infty$ initial datum which admits infinitely many bounded admissible weak solutions. Taking advantage of the relation between smooth solutions to the Euler system and to the Burgers equation we construct a smooth compression wave which collapses into a perturbed Riemann state at some time instant $T > 0$. In order to continue the solution after the formation of the discontinuity, we adjust and apply the theory developed by De Lellis and Sz\'ekelyhidi and we construct infinitely many solutions. We introduce the notion of an admissible generalized fan subsolution to be able to handle data which are not piecewise constant and we reduce the argument to finding a single generalized subsolution.
We study $N=2$ gauged supergravity with $U(1)$ gauge group coupled to $n_v$ vector multiplets and find quite general analytic solutions for quarter-BPS black holes with mass, NUT and dyonic Maxwell charges. The solutions we find have running scalar fields and flow in the IR region to a horizon geometry of the form AdS$_2\times \Sigma_g$.
Supernova remnants (SNRs) are believed to be the most important acceleration sites for cosmic rays (CRs) below $\sim10^{15}$ eV in the Galaxy. High energy photons, either directly from the shocks of the SNRs or indirectly from the interaction between SNRs and the nearby clouds, are crucial probes for the CR acceleration. Big progresses on observations of SNRs have been achieved by space- and ground-based $\gamma$-ray facilities. However, whether $\gamma$-rays come from accelerated hadrons or not, as well as their connection with the CRs observed at Earth, remains in debate. Large High Altitude Air Shower Observatory (LHAASO), the next generation experiment, is designed to survey the northern part of the very high energy $\gamma$-ray sky from $\sim 0.3$ TeV to PeV with the sensitivity of $\lesssim1\%$ of the Crab nebula flux. In this paper, we indicate that LHAASO will be dedicated to enlarging the $\gamma$-ray SNR samples and improving the spectral and morphological measurements. These measurements, especially at energies above 30 TeV, will be important for us to finally understand the CR acceleration in SNRs.
We present the theory of analytical Hartree-Fock gradients for periodic systems as implemented in the code CRYSTAL. We demonstrate how derivatives of the integrals can be computed with the McMurchie-Davidson algorithm. Highly accurate gradients with respect to nuclear coordinates are obtained for systems periodic in 0,1,2 or 3 dimensions.
We consider the Noether-Lefschetz problem for surfaces in Q-factorial normal 3-folds with rational singularities. We show the existence of components of the Noether-Lefschetz locus of maximal codimension, and that there are indeed infinitely many of them. Moreover, we show that their union is dense in the natural topology.
Let $X \subset \mathbb{C}^{2n}$ be an $n$-dimensional algebraic variety. We define the algebraic version of the generic symmetry defect set (Wigner caustic) of $X$. Moreover, we compute its singularities for $X_d$ being a generic curve of degree $d$ in $\mathbb{C}^2$.
We consider a `Scalar-Maxwell-Einstein-Gauss-Bonnet' theory in four dimension, where the scalar field couples non-minimally with the Gauss-Bonnet (GB) term. This coupling with the scalar field ensures the non topological character of the GB term. In such higher curvature scenario, we explore the effect of electromagnetic field on scalar field collapse. Our results reveal that the presence of a time dependent electromagnetic field requires an anisotropy in the background spacetime geometry and such anisotropic spacetime allows a collapsing solution for the scalar field. The singularity formed as a result of the collapse is found to be a curvature singularity which may be point like or line like depending on the strength of the anisotropy. We also show that the singularity is always hidden from exterior by an apparent horizon.
Introducing an epitaxial growth technique called corner overgrowth, we fabricate a quantum confinement structure consisting of a high-mobility GaAs/AlGaAs heterojunction overgrown on top of an ex-situ cleaved substrate corner. The resulting corner-junction quantum-well heterostructure effectively bends a two-dimensional electron system (2DES) at an atomically sharp $90^{\rm o}$ angle. The high-mobility 2DES demonstrates fractional quantum Hall effect on both facets. Lossless edge-channel conduction over the corner confirms a continuum of 2D electrons across the junction, consistent with Schroedinger-Poisson calculations of the electron distribution. This growth technique differs distinctly from cleaved-edge overgrowth and enables a complementary class of new embedded quantum heterostructures.
We study the internal circulation within the cocoon carved out by a relativistic jet emanating from an AGN, first developing model and then validating it using a series of numerical simulations. We notice that a significant increase of in this flow arises because gradients in the density and entropy develop near the hot spot, as a consequence of Crocco vorticity theorem. We find simple solutions for the streamlines, and we use them to predict the mass inflow rates towards the central regions. The 2D simulations we perform span a rather wide range of mechanical jet's input power and Black Hole masses, and we show that the predicted nuclear mass inflows are in good agreement with the theoretical model.
The effective strange quark and antiquark masses are estimated from the chiral soliton approach (CSA) results for the spectrum of exotic and nonexotic baryons. There are problems when one tries to project results of the CSA on the simple quark models (QM): the parameter in $1/N_c$ expansion is so large for the case of the baryon spectrum that extrapolation to the real $N_c=3$ world is not possible; rigid (as well soft) rotator model and the bound state model coincide in the first two orders in $1/N_c$, but differ in the next orders. There is correspondence of the CSA and simple QM predictions for pentaquarks (PQ) spectra in negative $S$ sector of the $\{27\}$ and $\{35\}$-plets: the effective mass of strange quark is about $135 -130\,MeV$, slightly smaller for $\{35\}$. For positive strangeness components the link between CSA and QM requires strong dependence of the effective $\bar{s}$ mass on particular SU(3) multiplet. The SU(3) configuration mixing is important, it pushes the spectrum towards the simplistic model (with equal masses of the strange quark and antiquark), and explanation of this nice property is lacking still. The success of the CSA in describing many properties of baryons and light nuclei (hypernuclei) means that predictions of pentaquark states should be considered seriously. Existence of PQ by itself is without any doubt, although very narrow PQ may not exist. Wide, even very wide PQ should exist, therefore, searches for PQ remain to be an actual task.
We consider that the direct production of a single neutralino in proton-proton collision at the CERN Large Hadron Collider focusing on the lightest neutralino is possibly a candidate for the dark matter and escapes detection. We present a comprehensive investigation of the dependence of total cross sections of the processes $pp(q\bar q)\rightarrow\widetilde\chi_{i}^{0}\widetilde{\text{g}}$, $pp(q \text{g}) \rightarrow\widetilde\chi_{i}^{0}\widetilde{q}_{L,R}$, $pp(q\bar{q}^{\prime})\rightarrow\widetilde\chi_{i}^{0}\widetilde\chi_{j}^{+}$ at tree-level and $pp(\text{g}\text{g})\rightarrow\widetilde\chi_{i}^{0}\widetilde{\text{g}}$ at one-loop level, on the center-of-mass energy, on the $M_2$-$\mu$ mass plane, on the squark mass and on the $\tan\beta$ for the Constrained Minimal Supersymmetric Standard Model and the three extremely different scenarios in the Minimal Supersymmetric Standard Model. In particular, the cross section of the process $p p \to \widetilde\chi_{2}^{0}\widetilde\chi_{1}^{+}$ in the gaugino-like scenario can reach about 0.6 (1.7) pb at a center-of-mass energy of $\sqrt{s}=$ 7 (14) TeV. We derive therefrom that our results might lead to new aspects corresponding to experimental explorations, and these dependencies might be used as bases of experimental research of the single neutralino production at hadron colliders.
We present measurements of the singly ionized helium to hydrogen ratio ($n_{He^+}/n_{H^+}$) toward diffuse gas surrounding three Ultra-Compact HII (UCHII ) regions: G10.15-0.34, G23.46-0.20 \& G29.96-0.02. We observe radio recombination lines (RRLs) of hydrogen and helium near 5 GHz using the GBT to measure the $n_{He^+}/n_{H^+}$ ratio. The measurements are motivated by the low helium ionization observed in the warm ionized medium (WIM) and in the inner Galaxy diffuse ionized regions (DIR). Our data indicate that the helium is not uniformly ionized in the three observed sources. Helium lines are not detected toward a few observed positions in sources G10.15-0.34 \& G23.46-0.20 and the upper limits of the $n_{He^+}/n_{H^+}$ ratio obtained are 0.03 and 0.05 respectively. The selected sources harbor stars of type O6 or hotter as indicated by helium line detection toward the bright radio continuum emission from the sources with mean $n_{He^+}/n_{H^+}$ value 0.06$\pm$0.02. Our data thus show that helium in diffuse gas located a few pc away from the young massive stars embedded in the observed regions is not fully ionized.We investigate the origin of the non-uniform helium ionization and rule out the possibilities : (a) that the helium is doubly ionized in the observed regions and (b) that the low $n_{He^+}/n_{H^+}$ values are due to additional hydrogen ionizing radiation produced by accreting low-mass stars (Smith 2014). We find that selective absorption of ionizing photons by dust can result in low helium ionization but needs further investigation to develop a self-consistent model for dust in HII regions.
Two well-known extended supersymmetric models, Z' models and NMSSM, are comparatively analyzed in the limit of large trilinear Higgs couplings. The two models are found to have distinguishable Higgs spectra at both tree- and loop- levels. Higgs production through Bjorken processes at an $e^+e^-$ collider is shown to discriminate between the two models.
Using a high cadence imaging spectropolarimetric observation of a sunspot and its surroundings in magnetically sensitive (FeI 6173 A) and insensitive (FeI 7090 A) upper photospheric absorption lines, we map the instantaneous wave phases and helioseismic travel times as a function of observation height and inclination of magnetic field to the vertical. We confirm the magnetic inclination angle dependent transmission of incident acoustic waves into upward propagating waves, and derive (1) proof that helioseismic travel times receive direction dependent contributions from such waves and hence cause errors in conventional flow inferences, (2) evidences for acoustic wave sources beneath the umbral photosphere, and (3) significant differences in travel times measured from the chosen magnetically sensitive and insensitive spectral lines.
It is shown that if the processes $B$ and $f(B)$ are both Brownian motions (without a random time change) then $f$ must be an affine function. As a by-product of the proof, it is shown that the only functions which are solutions to both the Laplace equation and the eikonal equation are affine.
We consider a particle system with a mean-field-type interaction perturbed by some common and individual noises. When the interacting kernels are sublinear and only locally Lipschitz-continuous, relying on arguments based on the tightness of random measures in Wasserstein spaces, we are able to construct a weak solution of the corresponding limiting SPDE. In a setup where the diffusion coefficient on the environmental noise is bounded, this weak convergence can be turned into a strong L^p($\Omega$) convergence and the propagation of chaos for the particle system can be established. The systems considered include perturbations of the Cucker-Smale model for collective motion.
Ce3+ doped oxide materials are promising for optical emission in the green spectral range. The growth of CaSc2O4:Ce3+ single crystals is reported here for the first time. Laser heated pedestal growth (LHPG) proved to be suitable for this refractive material, if performed in nitrogen of 99.999% purity. If the oxygen content of the growth atmosphere is substantially larger, Ce4+ is formed, which shows no useful optical emission. If the oxygen content is substantially lower, severe evaporation of calcium impedes stable crystal growth. Thermodynamic equilibrium calculations allowed to describe evaporation of species and cerium dopant charging under different growth conditions. The evaporation could be investigated by quadrupole mass spectrometry of emanating gases and by chemical analysis of fibers with ICP-OES. The congruent melting point was confirmed by DTA at 2110 degrees centigrade. Photoluminescence spectrometry of fibers revealed the dependence of optical emission in the green spectral range on growth conditions.
We have studied a flavor-changing toppion production process $e^{+}e^{-}\to t\bar{c}\Pi^{0}_{t}$ in the topcolor-assisted technicolor(TC2) model. The studies show that, with high centre of mass energy in TESLA collider, the production cross section of $e^{+}e^{-}\to t\bar{c}\Pi^{0}_{t}$ is at the order of magnitude 0.1 fb in most parameter regions of TC2 model and a few tens events of toppion can be produced each year. The resonance effect can enhance the cross section to a few fb when toppion mass is small.   With clean background, the toppion events can possibly be detected at TESLA collider. On the other hand, we find that there exists a narrow peak near $m_t-m_c$ in the toppion-charm invariant mass distribution which could be clearly detected. Therefore, such a toppion production process $e^{+}e^{-}\to t\bar{c}\Pi^{0}_{t}$ provides a unique chance to detect toppion events and test the TC2 model.
In 2017, D. Skabelund constructed a maximal curve over $\mathbb{F}_{q^4}$ as a cyclic cover of the Suzuki curve. In this paper we explicitly determine the structure of the Weierstrass semigroup at any point $P$ of the Skabelund curve. We show that its Weierstrass points are precisely the $\mathbb{F}_{q^4}$-rational points. Also we show that among the Weierstrass points, two types of Weierstrass semigroup occur: one for the $\mathbb{F}_q$-rational points, one for the remaining $\mathbb{F}_{q^4}$-rational points. For each of these two types its Ap\'ery set is computed as well as a set of generators.
In a graph $G$, a subset of vertices is a dissociation set if it induces a subgraph with vertex degree at most 1. A maximum dissociation set is a dissociation set of maximum cardinality. The dissociation number of $G$, denoted by $\psi(G)$, is the cardinality of a maximum dissociation set of $G$. Extremal problems involving counting the number of a given type of substructure in a graph have been a hot topic of study in extremal graph theory throughout the last few decades. In this paper, we determine the maximum number of maximum dissociation sets in a tree with prescribed dissociation number and the extremal trees achieving this maximum value.
In this paper we deal with anomalous diffusions induced by Continuous Time Random Walks - CTRW in $\mathbb{R}^n$. A particle moves in $\mathbb{R}^n$ in such a way that the probability density function $u(\cdot,t)$ of finding it in region $\Omega$ of $\mathbb{R}^n$ is given by $\int_{\Omega}u(x,t) dx$. The dynamics of the diffusion is provided by a space time probability density $J(x,t)$ compactly supported in $\{t\geq 0\}$. For $t$ large enough, $u$ must satisfy the equation $u(x,t)=[(J-\delta)\ast u](x,t)$ where $\delta$ is the Dirac delta in space time. We give a sense to a Cauchy type problem for a given initial density distribution $f$. We use Banach fixed point method to solve it, and we prove that under parabolic rescaling of $J$ the equation tends weakly to the heat equation and that for particular kernels $J$ the solutions tend to the corresponding temperatures when the scaling parameter approaches to zero.
High resolution spectra obtained from the Subaru Telescope High Dispersion Spectrograph have been used to update the stellar atmospheric parameters and metallicity of the star HD 209621. We have derived a metallicity of [Fe/H] = -1.93 for this star, and have found a large enhancement of carbon and of heavy elements, with respect to iron. Updates on the elemental abundances of four s-process elements (Y, Ce, Pr, Nd) along with the first estimates of abundances for a number of other heavy elements (Sr, Zr, Ba, La, Sm, Eu, Er, Pb) are reported. The stellar atmospheric parameters, the effective temperature, Teff, and the surface gravity, log g (4500 K, 2.0), are determined from LTE analysis using model atmospheres. Estimated [Ba/Eu] = +0.35, places the star in the group of CEMP-(r+s) stars; however, the s-elements abundance pattern seen in HD 209621 is characteristic of CH stars; notably, the 2nd-peak s-process elements are more enhanced than the first peak s-process elements. HD 209621 is also found to show a large enhancement of the 3rd-peak s-process element lead (Pb) with [Pb/Fe] = +1.88. The relative contributions of the two neutron-capture processes, r- and s- to the observed abundances are examined using a parametric model based analysis, that hints that the neutron-capture elements in HD 209621 primarily originate in s-process.
The demand for renewable and environmentally friendly energy source has attracted extensive research on high performance catalysts. Ferroelectrics which are a class of materials with a switchable polarization are the unique and promising catalyst candidates due to the significant effects of polarization on surfaces physical and chemical properties. The band bending at the ferroelectric/semiconductor interface induced by the polarization flip promotes the charge separation and transfer, there by enhancing the photocatalytic performance. More importantly, the reactants can be selectively adsorbed on the surface of the ferroelectric materials depending on the polarization direction, which can effectively lift the basic limitations as imposed by Sabatier principle on catalytic activity. This review summarizes the latest developments of ferroelectric materials, and introduces the ferroelectric-related catalytic application. The possible research directions of 2D ferroelectric materials in chemical catalysis is discussed at the end. The review is expected to inspire the extensive research interests from physical, chemical and material science communities.
The interplay of spin orbit coupling and electron electron interaction condensing new phases of matter is an important new phenomena in solid state physics. In this paper we explore the nature of excitonic phases induced in Weyl semimetals by long range Coulomb repulsion. Its has been previously shown that short range repulsion leads to a ferromagnetic insulator while short range attraction results in a charge density wave state. Here we show the the charge density wave is the energetically favored state in the presence of long range repulsion.
We carry out a comparative analysis of the GALLEX-GNO solar neutrino data and estimates of the solar internal rotation rate derived from the MDI helioseismology experiment on the SOHO spacecraft. We introduce a statistic, which we evaluate as a function of radius and latitude, that is a measure of the degree of "resonance" of oscillations in the neutrino flux and the synodic solar rotation rate at that radius and latitude. A map of this statistic indicates that the probable location is deep in the convection zone near the equator.   We also examine the integral of this statistic over the equatorial section of the convection zone. This provides a measure of the likelihood that the variability of the solar neutrino flux, as measured by the GALLEX-GNO data, has its origin in the equatorial section of the convection zone. We apply the shuffle test, randomly reassigning measurements among runs, to estimate the significance of the value of the statistic computed from the actual data. This test implies that the result is significant at the 0.2% level. When, for comparison, we repeat this analysis for the radiative zone, we find that the integral resonance statistic is not significant.   These results support earlier evidence for rotational modulation of the solar neutrino flux.
Using halo effective field theory (EFT), an expansion in $R_{core}/R_{halo}$, where $R_{core}$ is the radius of the core and $R_{halo}$ the radius of the halo nucleus, we calculate the charge and neutron form factors of the two-neutron halo nuclei $^{11}$Li, $^{14}$Be, and $^{22}$C to next-to-leading-order (NLO) by treating them as an effective three-body system. From the form factors we extract the point charge and point matter radii, inter-neutron distance, and neutron opening angle. Agreement is found with existing experimental extractions. Results are given for the point charge and point matter radii for arbitrary neutron core scattering effective range, $\rho_{cn}$, that can be used for predictions once $\rho_{cn}$ is measured. Estimates for $\rho_{cn}$ are also used to make NLO predictions. Finally, our point charge radii are compared to other halo-EFT predictions, and setting the core mass equal to the neutron mass our point charge radius is found to agree with an analytical prediction in the unitary limit.