ShantanuT01/DACTYL-Pretraining huggingface dataset:
The low-energy part of the vibration spectrum in KNbO$_3$ was studied by cold neutron inelastic scattering in the cubic phase. In addition to acoustic phonons, we observe strong diffuse scattering, which consists of two components. The first one is quasi-static and has a temperature-independent intensity. The second component appears as quasi-elastic scattering in the neutron spectrum indicating a dynamic origin. From analysis of the inelastic data we conclude that the quasi-elastic component and the acoustic phonon are mutually coupled. The susceptibility associated with the quasi-elastic component grows as the temperature approaches T$_C$.
In this article we illustrate the relation between the existence of Wiener integrals with respect to a Levy process in a separable Banach space and radonifying operators. For this purpose, we introduce the class of theta-radonifying operators, i.e. operators which map a cylindrical measure theta to a genuine Radon measure. We study this class of operators for various examples of infinitely divisible cylindrical measures theta and highlight the differences from the Gaussian case.
A few-shot font generation (FFG) method has to satisfy two objectives: the generated images should preserve the underlying global structure of the target character and present the diverse local reference style. Existing FFG methods aim to disentangle content and style either by extracting a universal representation style or extracting multiple component-wise style representations. However, previous methods either fail to capture diverse local styles or cannot be generalized to a character with unseen components, e.g., unseen language systems. To mitigate the issues, we propose a novel FFG method, named Multiple Localized Experts Few-shot Font Generation Network (MX-Font). MX-Font extracts multiple style features not explicitly conditioned on component labels, but automatically by multiple experts to represent different local concepts, e.g., left-side sub-glyph. Owing to the multiple experts, MX-Font can capture diverse local concepts and show the generalizability to unseen languages. During training, we utilize component labels as weak supervision to guide each expert to be specialized for different local concepts. We formulate the component assign problem to each expert as the graph matching problem, and solve it by the Hungarian algorithm. We also employ the independence loss and the content-style adversarial loss to impose the content-style disentanglement. In our experiments, MX-Font outperforms previous state-of-the-art FFG methods in the Chinese generation and cross-lingual, e.g., Chinese to Korean, generation. Source code is available at https://github.com/clovaai/mxfont.
Both IrV and RhV crystallize in the alpha-IrV structure, with a transition to the higher symmetry L1_0 structure at high temperature, or with the addition of excess Ir or Rh. Here we present evidence that this transition is driven by the lowering of the electronic density of states at the Fermi level of the alpha-IrV structure. The transition has long been thought to be second order, with a simple doubling of the L1_0 unit cell due to an unstable phonon at the R point (0 1/2 1/2). We use first-principles calculations to show that all phonons at the R point are, in fact, stable, but do find a region of reciprocal space where the L1_0 structure has unstable (imaginary frequency) phonons. We use the frozen phonon method to examine two of these modes, relaxing the structures associated with the unstable phonon modes to obtain new structures which are lower in energy than L1_0 but still above alpha-IrV. We examine the phonon spectra of these structures as well, looking for instabilities, and find further instabilities, and more relaxed structures, all of which have energies above the alpha-IrV phase. In addition, we find that all of the relaxed structures, stable and unstable, have a density comparable to the L1_0 phase (and less than the alpha-IrV phase), so that any transition from one of these structures to the ground state will have a volume change as well as an energy discontinuity. We conclude that the transition from L1_0 to alpha-IrV is probably weakly first order.
We propose a new scheme for quantum key distribution using macroscopic non-classical pulses of light having of the order 10^6 photons per pulse. Sub-shot-noise quantum correlation between the two polarization modes in a pulse gives the necessary sensitivity to eavesdropping that ensures the security of the protocol. We consider pulses of two-mode squeezed light generated by a type-II seeded parametric amplification process. We analyze the security of the system in terms of the effect of an eavesdropper on the bit error rates for the legitimate parties in the key distribution system. We also consider the effects of imperfect detectors and lossy channels on the security of the scheme.
We characterize all fields of definition for a given coherent sheaf over a projective scheme in terms of projective modules over a finite-dimensional endomorphism algebra. This yields general results on the essential dimension of such sheaves. Applying them to vector bundles over a smooth projective curve C, we obtain an upper bound for the essential dimension of their moduli stack. The upper bound is sharp if the conjecture of Colliot-Th\'el\`ene, Karpenko and Merkurjev holds. We find that the genericity property proved for Deligne-Mumford stacks by Brosnan, Reichstein and Vistoli still holds for this Artin stack, unless the curve C is elliptic.
Galaxies properties are known to be affected by their environment. One important question is how their angular momentum reflects the surrounding cosmic web. We use the SDSS to investigate the spin axes of spiral and elliptical galaxies relative to their surrounding filament/sheet orientations. To detect filaments a marked point process with interactions (the "Bisous model") is used. Sheets are found by detecting "flattened" filaments. The minor axes of ellipticals are found to be preferentially perpendicular to hosting filaments. A weak correlation is found with sheets. These findings are consistent with the notion that elliptical galaxies formed via mergers which predominantly occurred along the filaments. The spin axis of spiral galaxies is found to align with the host filament, with no correlation between spiral spin and sheet normal. When examined as a function of distance from the filament axis, a much stronger correlation is found in outer parts, suggesting that the alignment is driven by the laminar infall of gas from sheets to filaments. When compared with numerical simulations our results suggest that the connection between DM halo and galaxy spin is not straightforward. Our results provide an important input to the understanding of how galaxies acquire their angular momentum.
We investigate the ordering dynamics of the voter model with time-delayed interactions. The dynamical process in the $d$-dimensional lattice is shown to be equivalent to the first passage problem of a random walker in the $(d+1)$-dimensional strip of a finite width determined by the delay time. The equivalence reveals that the time delay leads to the dimensional crossover from the $(d+1)$-dimensional scaling behavior at short time to the $d$-dimensional scaling behavior in the long time. The scaling property in both regimes and the crossover time scale are obtained analytically, which are confirmed with the numerical simulation results.
It is shown that nuclear level densities in a finite space are described by a continuous binomial function, determined by the first three moments of the Hamiltonian, and the dimensionality of the underlying vector space. Experimental values for $^{55}$Mn, $^{56}$Fe, and $^{60}$Ni are very well reproduced by the binomial form, which turns out to be almost perfectly approximated by Bethe's formula with backshift. A proof is given that binomial densities reproduce the low moments of Hamiltonians of any rank: A strong form of the famous central limit result of Mon and French. Conditions under which the proof may be extended to the full spectrum are examined.
In this paper, it is proved that the jellyfish graphs, a natural generalization of sun graphs, are both DLS and DQS.
Motivated by the discovery of spiral and modulated collinear phases in several magnetic materials, we investigate the magnetic properties of Heisenberg spin S=1/2 antiferromagnets in 2 and 3 dimensions, with frustration arising from 2nd-neighbor couplings in one axial direction (the ANNNH model). Our results clearly demonstrate the presence of an incommensurate spiral phase at T=0 in 2 dimensions, extending to finite temperatures in 3 dimensions. The crossover between N\'eel and spiral order occurs at a value of the frustration parameter considerably above the classical value 0.25, a sign of substantial quantum fluctuations. We also investigate a possible modulated collinear phase with a wavelength of 4 lattice spacings, and find that it has substantially higher energy and hence is not realized in the model.
In this paper the soft gluon radiation from partonic interaction of the type: $2 \to 2$ + gluon has been revisited and a correction term to the widely used Gunion-Bertsch (GB) formula is obtained.
Despite their important applications in metrology and in spite of numerous experimental demonstrations, weak measurements are still confusing for part of the community. This sometimes leads to unjustified criticism. Recent papers have experimentally clarified the meaning and practical significance of weak measurements, yet in [R.E. Kastner, Found. Phys. 47, 697-707 (2017)], Kastner seems to take us many years backwards in the debate, casting doubt on the very term "weak value" and the meaning of weak measurements. Kastner appears to ignore both the basics and frontiers of weak measurements and misinterprets the weak measurement process and its outcomes. In addition, she accuses the authors of [Y. Aharonov et al., Ann. Phys. 355, 258-268 (2015)] in statements completely opposite to the ones they have actually made. There are many points of disagreement between Kastner and us, but in this short reply I will leave aside the ontology (which is indeed interpretational and far more complex than that described by Kastner) and focus mainly on the injustice in her criticism. I shall add some general comments regarding the broader theory of weak measurements and the Two-State-Vector Formalism (TSVF), as well as supporting experimental results. Finally, I will point out some recent promising results, which can be proven by (strong) projective measurements, without the need of employing weak measurements.
Graphene is a promising candidate for building fast and ultra-sensitive bolometric detectors due to its weak electron-phonon coupling and low heat capacity. In order to realize a practical graphene-based bolometer, several important issues, including the nature of radiation response, coupling efficiency to the radiation and the thermal conductance need to be carefully studied. Addressing these issues, we present graphene-superconductor junctions as a viable option to achieve efficient and sensitive bolometers, with the superconductor contacts serving as hot electron barriers. For a graphene-superconductor device with highly transparent interfaces, the resistance readout in the presence of radio frequency radiation is dominated by non-linear response. On the other hand, a graphene-superconductor tunnel device shows dominantly bolometric response to radiation. For graphene devices fabricated on $SiO_{2}$ substrates, we confirm recent theoretical predictions of $T^{2}$ temperature dependence of phonon thermal conductance in the presence of disorder in the graphene channel at low temperatures.
Beta eucryptite (LiAlSiO4) shows one-dimensional super-ionic conductivity as well as anisotropic thermal expansion behavior. We have performed inelastic neutron scattering measurements in beta eucryptite over 300 to 900 K and calculated the phonon spectrum using ab initio density functional theory method. The calculated energy profile for cooperative lithium ion displacements indicates preferential movement of Li ion along the hexagonal c-axis in the high temperature phase. However, the energy barrier for Li ion diffusion is significantly reduced when a Schottky defect is introduced in the crystal. Further, the anisotropic stress dependence of the phonon spectrum is calculated to obtain the thermal expansion behavior along various axes. The calculations show that the Gruneisen parameters of the low-energy phonon modes around 10 meV have large negative values and govern the negative thermal expansion behavior both along the a and c axes. On the other hand, anisotropic elasticity along with anisotropic positive values of the Gruneisen parameters of the high-energy modes in the range 30 to 70 meV are responsible for positive thermal expansion in the a-b plane and negative expansion along the c-axis. The analysis of the polarization vectors of the phonon modes sheds light on the mechanism of the anomalous thermal expansion behavior. We extend the study to discuss the relationship of the soft phonons in the Brillouin zone with the observed high-pressure and high-temperature phase transitions as reported in the literature.
We present the search methods and initial results for transient radio signals in the High Time Resolution Universe (HTRU) Survey. The HTRU survey's single-pulse search, the software designed to perform the search, and a determination of the HTRU survey's sensitivity to single pulses are described. Initial processing of a small fraction of the survey has produced 11 discoveries, all of which are sparsely-emitting neutron stars, as well as provided confirmation of two previously unconfirmed neutron stars. Most of the newly discovered objects lie in regions surveyed previously, indicating both the improved sensitivity of the HTRU survey observing system and the dynamic nature of the radio sky. The cycles of active and null states in nulling pulsars, rotating radio transients (RRATs), and long-term intermittent pulsars are explored in the context of determining the relationship between these populations, and of the sensitivity of a search to the various radio-intermittent neutron star populations. This analysis supports the case that many RRATs are in fact high-null-fraction pulsars (i. e. with null fraction >~0.95), and indicates that intermittent pulsars appear distinct from nulling pulsars in their activity cycle timescales. We find that in the measured population, there is a deficit of pulsars with typical emission timescales greater than ~300 s that is not readily explained by selection effects. The HTRU low-latitude survey will be capable of addressing whether this deficit is physical. We predict that the HTRU survey will explore pulsars with a broad range of nulling fractions (up to and beyond 0.999), and at its completion is likely to increase the currently known RRATs by a factor of more than two.
We present an output-sensitive algorithm for generating the whole set of flats of a finite matroid. Given a procedure, P, that decides in S_P time steps if a set is independent, the time complexity of the algorithm is O(N^2 M S_P), where N and M are the input and output size, respectively. In the case of vectorial matroids, a specific algorithm is reported whose time complexity is equal to O(N^2 M d^2), d being the rank of the matroid. In some cases this algorithm can provide an efficient method for computing zonotopes in $H$-representation, given their representation in terms of Minkowski sum of known segments.
The GUSBAD catalog of gamma-ray bursts (GRBs) is based on archival BATSE DISCLA data covering the full 9.1 years of the Compton Gamma Ray Observatory mission. The catalog contains 2204 GRBs, including 589 bursts not listed in the Current BATSE Burst Catalog. The GUSBAD catalog is uniform in the sense that the detection criteria are the same throughout and that the properties given in the catalog are available for every burst. The detection and the derivation of the properties of the GRBs were carried out automatically. This makes the GUSBAD catalog especially suitable for statistical work and simulations, such as used in the derivation of V/Vmax. We briefly touch upon a potential problem in defining a GRB duration that is physically meaningful.
Stochastic solutions provide new rigorous results for nonlinear PDE's and, through its local non-grid nature, are a natural tool for parallel computation. There are two different approaches for the construction of stochastic solutions: McKean's and superprocesses. In favour of superprocesses is the fact that they handle arbitrary boundary conditions. However, when restricted to measures, superprocesses can only be used to generate solutions for a limited class of nonlinear PDE's. A new class of superprocesses, namely superprocesses on ultradistributions, is proposed to extend the stochastic solution approach to a wider class of PDE's.
We show that the very young brown dwarf candidate ISO217 (M6.25) is driving an intrinsically asymmetric bipolar outflow with a stronger and slightly faster red-shifted component based on spectro-astrometry of forbidden [SII] emission lines observed in UVES/VLT spectra taken in 2009. ISO217 is only one of a handful of brown dwarfs and VLMS (M5-M8) for which an outflow has been detected and that show that the T Tauri phase continues at the substellar limit. We measure a spatial extension of the outflow of +/-190mas (+/-30AU) and velocities of +/-40-50kms/s. We show that the velocity asymmetry between both lobes is variable on timescales of a few years and that the strong asymmetry of a factor of 2 found in 2007 might be smaller than originally anticipated when using a more realistic stellar rest-velocity. We also detect forbidden [FeII]7155 emission, for which we propose as potential origin the hot inner regions of the outflow. To understand the ISO217 system, we determine the disk properties based on radiative transfer modeling of the SED. This disk model agrees very well with Herschel/PACS data at 70mu. We find that the disk is flared and intermediately inclined (~45deg). The total disk mass (4e-6 Msun) is small compared to the accretion and outflow rate of ISO217 (~1e-10 Msun/yr). We propose that this discrepancy can be explained by either a higher disk mass than inferred from the model (strong undetected grain growth) and/or by an on average lower accretion and outflow rate than the determined values. We show that a disk inclination significantly exceeding 45deg, as suggested from Halpha modeling and from both lobes of the outflow being visible, is inconsistent with the SED data. Thus, despite its intermediate inclination angle, the disk of this brown dwarf does not appear to obscure the red outflow component, which is very rarely seen for T Tauri objects (only one other case).
We study incidence properties among cosets of finite loops, with emphasis on well-structured varieties such as antiautomorphic loops and Bol loops. While cosets in groups are either disjoint or identical, we find that the incidence structure in general loops can be much richer. Every symmetric design, for example, can be realized as a canonical collection of cosets of a finite loop. We show that in the variety of antiautomorphic loops the poset formed by set inclusion among intersections of left cosets is isomorphic to that formed by right cosets. We present an algorithm that, given a finite Bol loop $S$, can in some cases determine whether $|S|$ divides $|Q|$ for all finite Bol loops $Q$ with $S \le Q$, and even whether there is a selection of left cosets of $S$ that partitions $Q$. This method results in a positive confirmation of Lagrange's Theorem for Bol loops for a few new cases of subloops. Finally, we show that in a left automorphic Moufang loop $Q$ (in particular, in a commutative Moufang loop $Q$), two left cosets of $S\le Q$ are either disjoint or they intersect in a set whose cardinality equals that of some subloop of $S$.
The regulation of angular momentum is one of the key processes for our understanding of stellar evolution. The rotational evolution of solar-mass stars is mainly determined by the magnetic interaction with their circumstellar disk and angular momentum loss through stellar winds, and In contrast to solar-mass stars, very low mass (VLM) objects and brown dwarfs are believed to be fully convective. This may lead to major differences of rotation and activity, since fully convective objects may not host a solar-type dynamo. Here, we report on our observational efforts to understand the rotational evolution of VLM objects. By means of photometric monitoring, we determined 62 rotation periods for targets in three clusters, which form an age sequence from 3 to 125 Myr. We find that VLM objects rotate faster than their solar-mass siblings in all evolutionary stages. Their rotational evolution seems to be determined by hydrostatic contraction and exponential angular momentum loss. The photometric amplitudes of the light curves are much lower than for solar-mass stars. This may be explained as a consequence of smaller spot coverage, more symmetric spot distributions, or lower contrast between spots and their environment. Most of these results can be explained with a change of the magnetic field properties with decreasing mass. VLM objects possibly possess only small-scale, turbulent magnetic fields.
Flare ribbons are always dynamic, and sometimes sweep across sunspots. Examining 588 (513 M-class and 75 X-class) flare events observed by Transition Region and Coronal Explorer (TRACE) satellite and Hinode Solar Optical Telescope (SOT) from 1998 May to 2009 May, we choose the event displaying that one of the flare ribbons completely sweeps across the umbra of a main sunspot of the corresponding active region, and finally obtain 20 (7 X-class and 13 M-class) events as our sample. In each event, we define the main sunspot completely swept across by the flare ribbon as A-sunspot, and its nearby opposite polarity sunspots, B-sunspot. Observations show that the A-sunspot is a following polarity sunspot in 18 events, and displays flux emergence in 13 cases. All the B-sunspots are relatively simple, exhibiting either one main sunspot or one main sunspot and several small neighboring sunspots (pores). In two days prior to the flare occurrence, the A-sunspot rotates in all the cases, while the B-sunspot, in 19 events. The total rotating angle of the A-sunspot and B-sunspot is 193 degrees on average, and the rotating directions, are the same in 12 events. In all cases, the A-sunspot and B-sunspot manifest shear motions with an average shearing angle of 28.5 degrees, and in 14 cases, the shearing direction is opposite to the rotating direction of the A-sunspot. We suggest that the emergence, the rotation and the shear motions of the A-sunspot and B-sunspot result in the phenomenon that flare ribbons sweep across sunspots completely.
We investigate the relation between the X-ray nuclear emission, optical emission line, radio luminosity and black hole mass for a sample of nearby Seyfert galaxies. Strong linear correlations between the 2-10 keV and [OIII], radio luminosities have been found, showing the same slopes found in quasars and luminous Seyfert galaxies, thus implying independence from the level of nuclear activity displayed by the sources. Moreover, despite the wide range of Eddington ratios (L/L(Edd)) tested here (six orders of magnitude, from 0.1 down to 10^(-7), no correlation is found between the X-ray, optical emission lines, radio luminosities and the black hole mass. These results suggest that low luminosity Seyfert galaxies are a scaled down version of luminous AGN and probably are powered by the same physical processes.