ShantanuT01/DACTYL-Pretraining huggingface dataset:
A process based on the exactly solvable Kipnis--Marchioro--Presutti model of heat conduction [J. Stat. Phys. 27 65 (1982)] is described whereby lattice cells share their energies among many identical degrees of freedom while, in each cell, only two of them are associated with energy exchanges connecting neighbouring cells. It is shown that, up to dimensional constants, the heat conductivity is half the interaction rate, regardless of the degrees of freedom. Moreover, as this number becomes large, correlations between the energy variables involved in the exchanges vanish. In this regime, the process thus boils down to the time-evolution of the local temperatures which is prescribed by the discrete heat equation.
Recent grain growth experiments have revealed that the same type of grain boundary can have very different mobilities depending on its local microstructure. In this work, we use molecular dynamics simulations to quantify uncertainty in the reduced mobility of curved grain boundaries for different types of boundary conditions and over a range of initial velocity seeds. We consider cylindrical island grains in Ni with a [001] tilt axis as a model system. Unexpectedly, we find large variation in the reduced mobility of curved grain boundaries depending on both the imposed constraints and the initial velocity distribution. We perform a dynamic propensity analysis inspired from studies of glass forming liquids to analyze sources of variation in reduced mobility. Our work highlights the significant impact of initial velocity distributions on grain boundary motion which has not been analyzed in prior work.
This paper is concerned with an interpretation of f-cohomology, a modification of motivic cohomology of motives over number fields, in terms of motives over number rings. Under standard assumptions on mixed motives over finite fields, number fields and number rings, we show that the two extant definitions of f-cohomology of mixed motives $M_\eta$ over F--one via ramification conditions on $\ell$-adic realizations, another one via the K-theory of proper regular models--both agree with motivic cohomology of $\eta_{!*} M_\eta[1]$. Here $\eta_{!*}$ is constructed by a limiting process in terms of intermediate extension functors $j_{!*}$ defined in analogy to perverse sheaves.
Evidence for small amounts of very hot plasma has been found in active regions and might be the indication of an impulsive heating, released at spatial scales smaller than the cross section of a single loop. We investigate the heating and substructure of coronal loops in the core of one such active region by analyzing the light curves in the smallest resolution elements of solar observations in two EUV channels (94 A and 335 A) from the Atmospheric Imaging Assembly on-board the Solar Dynamics Observatory. We model the evolution of a bundle of strands heated by a storm of nanoflares by means of a hydrodynamic 0D loop model (EBTEL). The light curves obtained from the random combination of those of single strands are compared to the observed light curves either in a single pixel or in a row of pixels, simultaneously in the two channels and using two independent methods: an artificial intelligent system (Probabilistic Neural Network, PNN) and a simple cross-correlation technique. We explore the space of the parameters to constrain the distribution of the heat pulses, their duration and their spatial size, and, as a feedback on the data, their signatures on the light curves. From both methods the best agreement is obtained for a relatively large population of events (1000) with a short duration (less than 1 min) and a relatively shallow distribution (power law with index 1.5) in a limited energy range (1.5 decades). The feedback on the data indicates that bumps in the light curves, especially in the 94 A channel, are signatures of a heating excess that occurred a few minutes before.
We extend the analysis of two-hadron fragmentation functions to the subleading twist, discussing also the issue of color gauge invariance. Our results can be used anywhere two unpolarized hadrons are semi-inclusively produced in the same fragmentation region, also at moderate values of the hard scale Q. Here, we consider the example of polarized deep-inelastic production of two hadrons and we give a complete list of cross sections and spin asymmetries up to subleading twist. Among the results, we highlight the possibility of extracting the transversity distribution with longitudinally polarized targets and also the twist-3 distribution e(x), which is related to the pion-nucleon sigma term and to the strangeness content of the nucleon.
We find general solutions to the generating-function equation sum c_q^{(X)} z^q = F(z)^X, where X is a complex number and F(z) is a convergent power series with |F(0)| >0. We then use these results to derive finite expressions containing only integers or simple fractions for partition functions and for Euler, Bernoulli, and Stirling numbers.
This paper presents FSNet, a deep generative model for image-based face swapping. Traditionally, face-swapping methods are based on three-dimensional morphable models (3DMMs), and facial textures are replaced between the estimated three-dimensional (3D) geometries in two images of different individuals. However, the estimation of 3D geometries along with different lighting conditions using 3DMMs is still a difficult task. We herein represent the face region with a latent variable that is assigned with the proposed deep neural network (DNN) instead of facial textures. The proposed DNN synthesizes a face-swapped image using the latent variable of the face region and another image of the non-face region. The proposed method is not required to fit to the 3DMM; additionally, it performs face swapping only by feeding two face images to the proposed network. Consequently, our DNN-based face swapping performs better than previous approaches for challenging inputs with different face orientations and lighting conditions. Through several experiments, we demonstrated that the proposed method performs face swapping in a more stable manner than the state-of-the-art method, and that its results are compatible with the method thereof.
Let X be a smooth algebraic curve of genus g>=2. A stable vector bundle over X of degree d, rank n with at least k sections is called a Brill-Noether bundle of type (n,d,k). By tensoring coherent systems, we prove that most of the known Brill-Noether bundles define coherent systems of type (n,d,k) that are alpha-stables for all allowable alpha .
In applied probability, the normal approximation is often used for the distribution of data with assumed additive structure. This tradition is based on the central limit theorem for sums of (independent) random variables. However, it is practically impossible to check the conditions providing the validity of the central limit theorem when the observed sample size is limited. Therefore it is very important to know what the real accuracy of the normal approximation is in the cases where it is used despite it is theoretically inapplicable. Moreover, in some situations related with computer simulation, if the distributions of separate summands in the sum belong to the domain of attraction of a stable law with characteristic exponent less than two, then the observed distance between the distribution of the normalized sum and the normal law first decreases as the number of summands grows and begins to increase only when the number of summands becomes large enough. In the present paper an attempt is undertaken to give some theoretical explanation to this effect.
Let $k$ be a positive integer and let $G$ be a graph with vertex set $V(G)$. A subset $D \subseteq V(G)$ is a $k$-dominating set if every vertex outside $D$ is adjacent to at least $k$ vertices in $D$. The $k$-domination number $\gamma_k(G)$ is the minimum cardinality of a $k$-dominating set in $G$. For any graph $G$, we know that $\gamma_k(G) \geq \gamma(G)+k-2$ where $ \Delta(G)\geq k\geq 2$ and this bound is sharp for every $k\geq 2$. In this paper, we characterize bipartite graphs satisfying the equality for $k\geq 3$ and present a necessary and sufficient condition for a bipartite graph to satisfy the equality hereditarily when $k=3$. We also prove that the problem of deciding whether a graph satisfies the given equality is NP-hard in general.
Highly nonlocal interparticle correlations in quantum Hall states of 2D charged system exposed to the perpendicular strong magnetic field are detailed by application of the commensurability condition upon path-integral quantization approach and examined by Monte-Carlo Metropolis simulations in perfect consistence with exact diagonalization of the Coulomb interaction in small models and with experimental data. In this way refined filling rate hierarchy in the lowest Landau level fully explains the experimentally collected features for FQHE at filling ratios predicted by the conventional composite fermion model as well as for those beyond the composite fermion model but also visible in the experiment. The trial wave functions for FQHE states are proposed using a systematic topological method revealing the different symmetry for different correlated states depending on filling fraction. A violation of fermionic antisymmetry for 2D electrons is evidenced for some filling rates related to specific correlations in FQHE.
In this work, we explore the role of atomistic-scale energetics on liquid-metal embrittlement of Al due to Ga. Ab initio and molecular mechanics were employed to probe the binding energies of vacancies and segregation energies of Ga for <100>, <110> and <111> STGBs in Al. We found that the GB local arrangements and resulting structural units have a significant influence on the magnitude of vacancy binding energies. For example, the mean vacancy binding energy for <100>, <110>, and <111> STGBs at 1st layer was found to be -0.63 eV, -0.26 eV, and -0.60 eV. However, some GBs exhibited vacancy binding energies closer to bulk values, indicating interfaces with zero sink strength, i.e., these GBs may not provide effective pathways for vacancy diffusion. The results from the present work showed that the GB structure and the associated free volume also play significant roles in Ga segregation and the subsequent embrittlement of Al. The Ga mean segregation energy for <100>, <110> and <111> STGBs at 1st layer was found to be -0.23 eV, -0.12 eV and -0.24 eV, respectively, suggesting a stronger correlation between the GB structural unit, its free volume, and segregation behavior. Furthermore, as the GB free volume increased, the difference in segregation energies between the 1st layer and the 0th layer increased. Thus, the GB character and free volume provide an important key to understanding the degree of anisotropy in various systems. The overall characteristic Ga absorption length scale was found to be about ~10, 8, and 12 layers for <100>, <110>, and <111> STGBs, respectively. Also, a few GBs of different tilt axes with relatively high segregation energies (between 0 and -0.1 eV) at the boundary were also found. This finding provides a new atomistic perspective to the GB engineering of materials with smart GB networks to mitigate or control LME and more general embrittlement phenomena in alloys.
We investigate the continuous quantum phase transition from an antiferromagnetic metal to a heavy fermion liquid based on the Kondo lattice model in two dimensions. We propose that antiferromagnetic spin fluctuations and conduction electrons fractionalize into neutral bosonic spinons and charged spinless fermions at the quantum critical point. This deconfined quantum criticality leads us to establish a critical field theory in terms of the fractionalized fields interacting via emergent U(1) gauge fields. The critical field theory not only predicts non-Fermi liquid physics near the quantum critical point but also recovers Fermi liquid physics away from the quantum critical point.
We numerically solve a discretized model of Levy random walks on a finite one-dimensional domain in the presence of sources and with a reflection coefficient $r$. At the domain boundaries, the steady-state density profile is non-analytic. The meniscus exponent $\mu$, introduced to characterize this singular behavior, uniquely identifies the whole profile. Numerical data suggest that $\mu =\alpha/2 + r(\alpha/2-1)$, where $\alpha$ is the Levy exponent of the step-length distribution. As an application, we show that this model reproduces the temperature profiles obtained for a chain of oscillators displaying anomalous heat conduction. Remarkably, the case of free-boundary conditions in the chain correspond to a Levy walk with negative reflection coefficient.
We analyze the transport in disordered two-dimensional nanoparticle arrays. We show that the commonly used scaling hypothesis to fit the I-V curves does not describe the electronic transport in these systems. On the contrary, close to the threshold voltage V_T the current depends linearly on (V-V_T). This linear behavior is observed for at least five decades in (V-V_T). Fitting the I-V curves at larger voltages to a scaling power-law I \propto (V/V_T-1)^\xi results in fitting parameters which depend on the range of voltages used and in wrong values for V_T. Our results urge to change the picture of electronic transport in disordered nanoparticle arrays used in the last two decades.
We present two algorithms to list certain classes of monomino-domino coverings which conform to the \emph{tatami} restriction; no four tiles meet. Our methods exploit structural features of tatami coverings in order to create the lists in $O(1)$ time per covering. This is faster than known methods for generating certain classes of matchings in bipartite graphs.   We discuss tatami coverings of $n\times n$ grids with $n$ monominoes and $v$ vertical dominoes, as well as tatami coverings of a two-way infinitely-wide strip of constant height, subject to the constraint that they have a finite number of non-trivial structural "features".   These two classes are representative of two differing structural characterisations of tatami coverings which may be adapted to count other classes of tatami coverings or locally restricted matchings, such as tatami coverings of rectangles.
The paper analyzes the structure and dynamics of a quiescent prominence that occurred on October 22, 2013. We aim to determine the physical characteristics of the observed prominence using MgII k and h, CII (1334 and 1336 A), and SiIV (1394 A) lines observed by IRIS. We employed the 1D non-LTE modeling of MgII lines assuming static isothermal-isobaric slabs. We selected a large grid of models with realistic input parameters and computed synthetic MgII lines. The method of Scargle periodograms was used to detect possible prominence oscillations. We analyzed 2160 points of the observed prominence in five different sections along the slit averaged over ten pixels due to low signal to noise ratio in the CII and SiIV lines. We computed the integrated intensity for all studied lines, while the central intensity and reversal ratio was determined only for both MgII and CII 1334 lines. We plotted several correlations: time evolution of the integrated intensities and central intensities, scatter plots between all combinations of line integrated intensities, and reversal ratio as a function of integrated intensity. We also compared MgII observations with the models. Results show that more than two-thirds of MgII profiles and about one-half of CII 1334 profiles are reversed. Profiles of SiIV are generally unreversed. The MgII and CII lines are optically thick, while the SiIV line is optically thin. The studied prominence shows no global oscillations in the MgII and CII lines. Therefore, the observed time variations are caused by random motions of fine structures with velocities up to 10 km/s. The observed average ratio of MgII k to MgII h line intensities can be used to determine the prominence's characteristic temperature. Certain disagreements between observed and synthetic line intensities of MgII lines point to the necessity of using more complex 2D multi-thread modeling in the future.
We show that the non flat factor of the Godel metric belongs to a one parameter family of 2+1 dimensional geometries that also includes the anti-de Sitter metric. The elements of this family allow a generalization a la Kaluza-Klein of the usual 3+1 dimensional Godel metric. Their lightcones can be viewed as deformations of the anti-de Sitter ones, involving tilting and squashing. This provides a simple geometric picture of the causal structure of these space-times, anti-de Sitter geometry appearing as the boundary between causally safe and causally pathological spaces. Furthermore, we construct a global algebraic isometric embedding of these metrics in 4+3 or 3+4 dimensional flat spaces, thereby illustrating in another way the occurrence of the closed timelike curves.
By expanding the reduced Pfaffian in the tree level Cachazo-He-Yuan (CHY) integrands for Yang-Mills (YM) and nonlinear sigma model (NLSM), we can get the Bern-Carrasco-Johansson (BCJ) numerators in Del Duca-Dixon-Maltoni (DDM) form for arbitrary number of particles in any spacetime dimensions. In this work, we give a set of very straightforward graphic rules based on spanning trees for a direct evaluation of the BCJ numerators for YM and NLSM. Such rules can be derived from the Laplace expansion of the corresponding reduced Pfaffian. For YM, the each one of the $(n-2)!$ DDM form BCJ numerators contains exactly $(n-1)!$ terms, corresponding to the increasing trees with respect to the color order. For NLSM, the number of nonzero numerators is at most $(n-2)!-(n-3)!$, less than those of several previous constructions.
Inversion codes are numerical tools used for the inference of physical properties from the observations. Despite their success, the quality of current spectropolarimetric observations and those expected in the near future presents a challenge to current inversion codes. The pixel-by-pixel strategy of inverting spectropolarimetric data that we currently utilize needs to be surpassed and improved. The inverted physical parameters have to take into account the spatial correlation that is present in the data and that contains valuable physical information. We utilize the concept of sparsity or compressibility to develop an new generation of inversion codes for the Stokes parameters. The inversion code uses numerical optimization techniques based on the idea of proximal algorithms to impose sparsity. In so doing, we allow for the first time to exploit the presence of spatial correlation on the maps of physical parameters. Sparsity also regularizes the solution by reducing the number of unknowns. We compare the results of the new inversion code with pixel-by-pixel inversions, demonstrating the increase in robustness of the solution. We also show how the method can easily compensate for the effect of the telescope point spread function, producing solutions with an enhanced contrast.
Heterogeneous face recognition (HFR) refers to matching face imagery across different domains. It has received much interest from the research community as a result of its profound implications in law enforcement. A wide variety of new invariant features, cross-modality matching models and heterogeneous datasets being established in recent years. This survey provides a comprehensive review of established techniques and recent developments in HFR. Moreover, we offer a detailed account of datasets and benchmarks commonly used for evaluation. We finish by assessing the state of the field and discussing promising directions for future research.
We present a general microscopic first-principles method to study the Coulomb-interaction-mediated heat transfer in the near field. Using the nonequilibrium Green's function formalism, we derive Caroli formulas for heat transfers between materials with translational invariance. The central physical quantities are the screened Coulomb potential and the spectrum function of polarizability. Within the random phase approximation, we calculate the polarizability using the linear response density functional theory and obtain the screened Coulomb potential from a retarded Dyson equation. We show that the heat transfer mediated by the Coulomb interaction is consistent with that of the $p$-polarized evanescent waves which dominate the heat transfer in the near field. We adopt single-layer graphene as an example to calculate heat transfers between two parallel sheets separated by a vacuum gap $d$. Our results show a saturation of heat flux at the extreme near field which is different from the reported $1/d$ dependence for local response functions. The calculated heat flux is up to $5\times10^4$ times more than the black-body limit, and a $1/d^2$ dependence is shown at large separations. From the spectrum of energy current density, we infer that the near-field enhancement of heat transfer stems from electron transitions around the Fermi energy. With a uniform strain, the heat flux increases for most of the distances while a negative correlation is shown at the moderate field. Our method is valid for inhomogeneous materials in which the macroscopic response function used in conventional theory of fluctuational electrodynamics would fail at the subnanometer scale.
Some questions arising in the application of the thermal model to hadron production in heavy ion collisions are studied. We do so by applying the thermal model of hadron production to particle yields calculated by the microscopic transport model RQMD(v2.3). We study the bias of incomplete information about the final hadronic state on the extraction of thermal parameters.It is found that the subset of particles measured typically in the experiments looks more thermal than the complete set of stable particles. The hadrons which show the largest deviations from thermal behaviour in RQMD(v2.3) are the multistrange baryons and antibaryons. We also looked at the influence of rapidity cuts on the extraction of thermal parameters and found that they lead to different thermal parameters and larger disagreement between the RQMD yields and the thermal model.
We have recently employed periodic Anderson model with electron-phonon interactions to describe Cerium volume collapse ($\gamma \rightarrow \alpha$ transition) under pressure. To describe the volume collapse transition in Cerium, we have tried to plot the pressure versus volume curves and see when a kink structure emerges. One way to obtain the pressure versus volume curve is to calculate the total energy of the system at different temperatures. In order to solve the periodic Anderson model with electron-phonon interactions, we have used the continuous time quantum Monte Carlo algorithm by integrating out the phonons to obtain a retarded electron-electron interaction. Monte Carlo simulation results give us the model's electronic Green function and self energy, from which we can calculate the system's total energy. A well known formula for calculating total energy through the knowledge of electron's self energy and Green function is derived from the model's Hamiltonian, which is not available for our case. Here, we have devised a new method to derive the total energy formula purely from a path integral description of the system, without resort to its Hamiltonian formulation. Since not all systems can be described by a Hamiltonian, thus our method has a wider applicability. It is noteworthy that the total energy formula that we derived here takes an identical form with that obtained from a model's Hamiltonian.
We show that the collective vibrational model of atomic nuclei displays quantum chaos. To avoid the problems related to the tunneling effects, a Green function deterministic numerical method has been used to evaluate the energy levels.