ShantanuT01/DACTYL-Pretraining huggingface dataset:
Lensing of the CMB is an important effect, and is usually modelled by remapping the unlensed CMB fields by a lensing deflection. However the lensing deflections also change the photon path so that the emission angle is no longer orthogonal to the background last-scattering surface. We give the first calculation of the emission-angle corrections to the standard lensing approximation from dipole (Doppler) sources for temperature and quadrupole sources for temperature and polarization. We show that while the corrections are negligible for the temperature and E-mode polarization, additional large-scale B-modes are produced with a white spectrum that dominates those from post-Born field rotation (curl lensing). On large scales about one percent of the total lensing-induced B-mode amplitude is expected to be due to this effect. However, the photon emission angle does remain orthogonal to the perturbed last-scattering surface due to time delay, and half of the large-scale emission-angle B modes cancel with B modes from time delay to give a total contribution of about half a percent. While not important for planned observations, the signal could ultimately limit the ability of delensing to reveal low amplitudes of primordial gravitational waves.We also derive the rotation of polarization due to multiple deflections between emission and observation. The rotation angle is of quadratic order in the deflection angle, and hence negligibly small: polarization typically rotates by less than an arcsecond, orders of magnitude less than a small-scale image rotates due to post-Born field rotation (which is quadratic in the shear). The field-rotation B modes dominate the other effects on small scales.
The observed large rates of spinning down after glitches in some radio pulsars has been previously explained in terms of a long-term spin-up behaviour of a superfluid part of the crust of neutron stars. We argue that the suggested mechanism is not viable; being inconsistent with the basic requirements for a superfluid spin-up, in addition to its quantitative disagreement with the data. One may therefore conclude, for the first time, that the presence and the pinned nature of neutron superfluid in the core of neutron stars is evidenced by the existing observational data.
We perform an all-sky analysis of the general relativistic galaxy power spectrum using the well-developed spherical Fourier decomposition. Spherical Fourier analysis expresses the observed galaxy fluctuation in terms of the spherical harmonics and spherical Bessel functions that are angular and radial eigenfunctions of the Helmholtz equation, providing a natural orthogonal basis for all-sky analysis of the large-scale mode measurements. Accounting for all the relativistic effects in galaxy clustering, we compute the spherical power spectrum and its covariance matrix and compare it to the standard three-dimensional power spectrum to establish a connection. The spherical power spectrum recovers the three-dimensional power spectrum at each wavenumber k with its angular dependence mu_k encoded in angular multipole l, and the contributions of the line-of-sight projection to galaxy clustering such as the gravitational lensing effect can be readily accommodated in the spherical Fourier analysis. A complete list of formulas for computing the relativistic spherical galaxy power spectrum is also presented.
The local density of states (LDOS) in a one-dimensional helical channel of finite length is studied within a Tomonaga-Luttinger model at zero temperature. Two particular cases of loop and Josephson junction geometries are considered. The LDOS, as a function of energy $\omega$ measured from the Fermi level, consists of equally spaced spikes of the $\delta$-function type, and electron-electron interactions modify their relative height. It is shown that, in the loop geometry, the height of spikes decreases as $\omega \to 0$ everywhere in the system. It is also shown that, in the Josephson junction, the behavior of the LDOS significantly depends on the spatial position. At the end points of the junction, the height increases as $\omega \to 0$ and its variation is more pronounced than that in the loop case. Away from the end points, the height of spikes shows a non-monotonic $\omega$-dependence, which disappears in the long-junction limit.
We consider a stochastic model of incompressible non-Newtonian fluids of second grade on a bounded domain of $\mathbb{R}^2$ driven by L\'evy noise. Applying the variational approach, global existence and uniqueness of strong probabilistic solution is established.
We propose a design for the construction of a laboratory system based on present-day technology which reproduces and thereby simulates the quantum dynamics of the O(3) nonlinear sigma model. Apart from its relevance in condensed-matter theory, this strongly interacting quantum field theory serves as an important toy model for quantum chromo-dynamics (QCD) since it reproduces many crucial properties of QCD. PACS: 03.67.-a, 03.67.Lx, 11.10.Kk, 68.65.-k.
We present a study of the luminosity and color properties of galaxies selected from a sample of 57 low-redshift Abell clusters. We utilize the non-parametric dwarf-to-giant ratio (DGR) and the blue galaxy fraction (fb) to investigate the clustercentric radial-dependent changes in the cluster galaxy population. Composite cluster samples are combined by scaling the counting radius by r200 to minimize radius selection bias. The separation of galaxies into a red and blue population was achieved by selecting galaxies relative to the cluster color-magnitude relation. The DGR of the red and blue galaxies is found to be independent of cluster richness (Bgc), although the DGR is larger for the blue population at all measured radii. A decrease in the DGR for the red and red+blue galaxies is detected in the cluster core region, while the blue galaxy DGR is nearly independent of radius. The fb is found not to correlate with Bgc; however, a steady decline toward the inner-cluster region is observed for the giant galaxies. The dwarf galaxy fb is approximately constant with clustercentric radius except for the inner cluster core region where fb decreases. The clustercentric radial dependence of the DGR and the galaxy blue fraction, indicates that it is unlikely that a simple scenario based on either pure disruption or pure fading/reddening can describe the evolution of infalling dwarf galaxies; both outcomes are produced by the cluster environment.
In this paper we prove that for a nonsingular projective variety of dimension at most 4 and with non-negative Kodaira dimension, the Kodaira dimension of coherent subsheaves of $\Omega^p$ is bounded from above by the Kodaira dimension of the variety. This implies the finiteness of the fundamental group for such an $X$ provided that $X$ has vanishing Kodaira dimension and non-trivial holomorphic Euler characteristic.
We show that bilayer graphene exhibits magneto-electric effects that are formally similar to those commonly seen in band insulators with broken inversion and time-reversal symmetries. Three unusual features characterize the magneto-electric responses exhibited by bilayer graphene: (i) unlike most other magneto-electric media, bilayer graphene is a conductor, (ii) bilayer graphene has a non-quantized magneto-electric coupling even though its electronic structure does not break parity and time-reversal symmetry, and (iii) the magnitude of the magneto-electric coupling in bilayer graphene is determined by the valley-isospin density, which can be manipulated experimentally. This last property also enables a purely electric measurement of valley-isospin densities. While our theoretical arguments use bilayer graphene as an example, they are generally valid for any material with similar symmetries.
A general method is presented for computing matrix elements of quark operators on baryonic states with low strangeness and arbitrary number of colors Nc. These results are useful in applications of the large Nc expansion to baryons and exotics. As an application we compute the matrix elements of strangeness changing operators contributing to kaon couplings to ground state baryons and pentaquarks, in broken SU(3).
Two groups recently deduced the positive value for the cosmological constant, concluding at a high (>= 99%) confidence level that the Universe should be accelerating. This conclusion followed from the statistical analysis of dozens of high-redshift supernovae. In this paper this conclusion is discussed. From the conservative frequentist's point of view the validity of null hypothesis of the zero cosmological constant is tested by the classical statistical chi^2 test for the 60 supernovae listed in Perlmutter et al. 1999 (ApJ, 517, 565). This sample contains 42 objects discovered in the frame of Supernova Cosmology Project and 18 low-redshift object detected earlier. Excluding the event SN1997O, which is doubtlessly an outlier, one obtains the result: The probability for seeing a worse chi^2 - if the null hypothesis is true - is in the 5% to 8% range, a value that does not indicate significant evidence againts the null. If one excludes further five possible outliers, proposed to be done by Perlmutter et al. 1999, then the sample of 54 supernovae is in an excellent accordance with the null hypothesis. It also seems that upernovae from the High-z Supernova Search Team does not change the acceptance of null hypothesis. This means that the rejection of the Einstein equations with zero cosmological constant - based on the supernova data alone - is still premature.
This paper presents the performance evaluation of eight focus measure operators namely Image CURV (Curvature), GRAE (Gradient Energy), HISE (Histogram Entropy), LAPM (Modified Laplacian), LAPV (Variance of Laplacian), LAPD (Diagonal Laplacian), LAP3 (Laplacian in 3D Window) and WAVS (Sum of Wavelet Coefficients). Statistical matrics such as MSE (Mean Squared Error), PNSR (Peak Signal to Noise Ratio), SC (Structural Content), NCC (Normalized Cross Correlation), MD (Maximum Difference) and NAE (Normalized Absolute Error) are used to evaluate stated focus measures in this research. . FR (Full Reference) method of the image quality assessment is utilized in this paper. Results indicate that LAPD method is comparatively better than other seven focus operators at typical imaging conditions.
The distributions of L(oiii 5007), black hole (BH) mass and L/L(Edd) in two large samples of type-I and type-II active galactic nuclei (AGNs) are compared in order to test the suggestion that radiation pressure force is affecting the gas velocity in the broad line region and hence the BH mass determination. The samples are drawn from the SDSS archive and are modified to represent the same parent distribution at 0.1 < z < 0.2. BH masses in type-I sources are calculated in two different ways, one using a simple virial mass assumption and the other by taking into account the effect of radiation pressure force on the gas. The simple virial mass estimate results in good agreement with the sigma*-based BH mass and L/L(Edd) estimates in type-II sources. In contrast, there is a clear disagreement in the L/L(Edd) distributions when radiation pressure-based estimates are used. This indicates that radiation pressure force is not important in 0.1 < z < 0.2 AGNs with L(5100)=10^{42.8-44.8} erg/s. This has important implications to the physics of the gas producing the broad emission lines in AGNs, in particular the existence of extremely large (about 10^24 cm^(-2)) column density clouds.
Fluorescence studies of natural photosynthetic complexes on a graphene layer demonstrate pronounced influence of the excitation wavelength on the energy transfer efficiency to graphene. Ultraviolet light yields much faster decay of fluorescence, with average efficiencies of the energy transfer equal to 87% and 65% for excitation at 405 nm and 640 nm, respectively. This implies that focused light changes locally the properties of graphene affecting the energy transfer dynamics, in an analogous way as in the case of metallic nanostructures. Demonstrating optical control of the energy transfer is important for exploiting unique properties of graphene in photonic and sensing architectures.
The electronic structure of nanoscopic oxide-coated aluminum islands is investigated using a tight-binding model that incorporates the geometry, chemistry and disorder of the particle. The oxide coat is found to significantly increase the volume accessible to electrons at the Fermi level. The level statistics agree with random matrix theory predictions. States near the Fermi level show pronounced clustering regardless of disorder. It is suggested that the observed clusters of tunneling resonances may have a more complex origin than if they were solely due to many-body non-equilibrium effects.
We study the evolution of passive scalars in both rigid and moving slab-like domains, in both horizontally periodic and infinite contexts. The scalar is required to satisfy Robin-type boundary conditions corresponding to Newton's law of cooling, which lead to nontrivial equilibrium configurations. We study the equilibration rate of the passive scalar in terms of the parameters in the boundary condition and the equilibration rates of the background velocity field and moving domain.
We present Sedonu, a new open source, steady-state, special relativistic Monte Carlo (MC) neutrino transport code, available at bitbucket.org/srichers/sedonu. The code calculates the energy- and angle-dependent neutrino distribution function on fluid backgrounds of any number of spatial dimensions, calculates the rates of change of fluid internal energy and electron fraction, and solves for the equilibrium fluid temperature and electron fraction. We apply this method to snapshots from two-dimensional simulations of accretion disks left behind by binary neutron star mergers, varying the input physics and comparing to the results obtained with a leakage scheme for the case of a central black hole and a central hypermassive neutron star. Neutrinos are guided away from the densest regions of the disk and escape preferentially around 45 degrees from the equatorial plane. Neutrino heating is strengthened by MC transport a few scale heights above the disk midplane near the innermost stable circular orbit, potentially leading to a stronger neutrino-driven wind. Neutrino cooling in the dense midplane of the disk is stronger when using MC transport, leading to a globally higher cooling rate by a factor of a few and a larger leptonization rate by an order of magnitude. We calculate neutrino pair annihilation rates and estimate that an energy of 2.8e46 erg is deposited within 45 degrees of the symmetry axis over 300 ms when a central BH is present. Similarly, 1.9e48 erg is deposited over 3 s when an HMNS sits at the center, but neither estimate is likely to be sufficient to drive a GRB jet.
Functional magnetic resonance imaging (fMRI) is a neuroimaging modality that captures the blood oxygen level in a subject's brain while the subject either rests or performs a variety of functional tasks under different conditions. Given fMRI data, the problem of inferring the task, known as task state decoding, is challenging due to the high dimensionality (hundreds of million sampling points per datum) and complex spatio-temporal blood flow patterns inherent in the data. In this work, we propose to tackle the fMRI task state decoding problem by casting it as a 4D spatio-temporal classification problem. We present a novel architecture called Brain Attend and Decode (BAnD), that uses residual convolutional neural networks for spatial feature extraction and self-attention mechanisms for temporal modeling. We achieve significant performance gain compared to previous works on a 7-task benchmark from the large-scale Human Connectome Project-Young Adult (HCP-YA) dataset. We also investigate the transferability of BAnD's extracted features on unseen HCP tasks, either by freezing the spatial feature extraction layers and retraining the temporal model, or finetuning the entire model. The pre-trained features from BAnD are useful on similar tasks while finetuning them yields competitive results on unseen tasks/conditions.
We present the results of our survey searching for new white dwarf pulsators for observations by the TESS space telescope. We collected photometric time-series data on 14 white dwarf variable-candidates at Konkoly Observatory, and found two new bright ZZ Ceti stars, namely EGGR 120 and WD 1310+583. We performed the Fourier-analysis of the datasets. In the case of EGGR 120, which was observed on one night only, we found one significant frequency at 1332 microHz with 2.3 mmag amplitude. We successfully observed WD 1310+583 on eight nights, and determined 17 significant frequencies by the whole dataset. Seven of them seem to be independent pulsation modes between 634 and 2740 microHz, and we performed preliminary asteroseismic investigations of the star utilizing six of these periods. We also identified three new light variables on the fields of white dwarf candidates: an eclipsing binary, a candidate delta Scuti/beta Cephei and a candidate W UMa-type star.
The recently developed weakly nonlinear theory of dynamic fracture predicts $1/r$ corrections to the standard asymptotic linear elastic $1/\sqrt{r}$ displacement-gradients, where $r$ is measured from the tip of a tensile crack. We show that the $1/r$ singularity does not automatically conform with the notion of autonomy (autonomy means that any crack tip nonlinear solution is uniquely determined by the surrounding linear elastic $1/\sqrt{r}$ fields) and that it does not automatically satisfy the resultant Newton's equation in the crack parallel direction. We show that these two properties are interrelated and that by requiring that the resultant Newton's equation is satisfied, autonomy of the $1/r$ singular solution is retained. We further show that the resultant linear momentum carried by the $1/r$ singular fields vanishes identically. Our results, which reveal the physical and mathematical nature of the new solution, are in favorable agreement with recent near tip measurements.
We review our recent studies demonstrating that the radiation pressure problem in the formation of massive stars can be circumvented via an anisotropy of the thermal radiation field. Such an anisotropy naturally establishes with the formation of a circumstellar disk. The required angular momentum transport within the disk can be provided by developing gravitational torques. Radiative Rayleigh-Taylor instabilities in the cavity regions - as previously suggested in the literature - are not required and are shown to be not occurring in the context of massive star formation.
We derive the couplings of noncommutative D-branes to spatially varying Ramond-Ramond fields, extending our earlier results in hep-th/0009101. These couplings are expressed in terms of *n products of operators involving open Wilson lines. Equivalence of the noncommutative to the commutative couplings implies interesting identities as well as an expression for the Seiberg-Witten map that was previously conjectured. We generalise our couplings to include transverse scalars, thereby obtaining a Seiberg-Witten map relating commutative and noncommutative descriptions of these scalars. RR couplings for unstable non-BPS branes are also proposed.
A string is the one-dimensional generalization of a point particle. In this sense, the analog of a cloud of dust would be a cloud of strings. In this work, we consider a cloud of strings around a regular solution in general gelativity. We consider the Bardeen solution and the Simpson--Visser solution, analyzing the consequences of the cloud in the regularity and in the energy conditions. Actually, the presence of the cloud could make the energy density positive when compared to the Simpson--Visser case. We verify that the usual Bardeen solution becomes singular in the presence of the cloud of string while the Simpson--Visser solution is still regular, violating the energy conditions, as the usual solution. We also calculate some thermodynamic quantities to evaluate how a cloud of strings influences the thermodynamics of the solutions.
Ehrhart theory measures a polytope P discretely by counting the lattice points inside its dilates P, 2P, 3P, .... We compute the Ehrhart quasipolynomials of the standard Coxeter permutahedra for the classical Coxeter groups, expressing them in terms of the Lambert W function. A central tool is a description of the Ehrhart theory of a rational translate of an integer zonotope.
We describe a procedure for mapping a self-consistent mean-field theory (also known as density functional theory) into a shell model Hamiltonian that includes quadrupole-quadrupole and monopole pairing interactions in a truncated space. We test our method in the deformed N=Z sd-shell nuclei Ne-20, Mg-24 and Ar-36, starting from the Hartree-Fock plus BCS approximation of the USD shell model interaction. A similar procedure is then followed using the SLy4 Skyrme energy density functional in the particle-hole channel plus a zero-range density-dependent force in the pairing channel. Using the ground-state solution of this density functional theory at the Hartree-Fock plus BCS level, an effective shell model Hamiltonian is constructed. We use this mapped Hamiltonian to extract quadrupolar and pairing correlation energies beyond the mean field approximation. The rescaling of the mass quadrupole operator in the truncated shell model space is found to be almost independent of the coupling strength used in the pairing channel of the underlying mean-field theory.
We use the language and tools available in model theory to redefine and clarify the rather involved notion of a {\em special subvariety} known from the theory of Shimura varieties (mixed and pure).
The phonon Hall effect has been observed in the paramagnetic insulator, Tb3Gd5O12. A magnetic field applied perpendicularly to a heat current induces a temperature gradient that is perpendicular to both the field and the current. We show that this effect is due to resonant skew scattering of phonons from the crystal field states of superstoichiometric Tb^3+ ions. This scattering originates from the coupling between the quadrupole moment of Tb^3+ ions and the lattice strain. The estimated magnitude of the effect is consistent with experimental observations at T=5 K, and can be significantly enhanced by increasing temperature.
We demonstrate that continuous-variable quantum error correction based on Gaussian ancilla states and Gaussian operations (for encoding, syndrome extraction, and recovery) can be very useful to suppress the effect of non-Gaussian error channels. For a certain class of stochastic error models, reminiscent of those typically considered in the qubit case, quantum error correction codes designed for single-channel errors may enhance the transfer fidelities even when errors occur in every channel employed for transmitting the encoded state. In fact, in this case, the error-correcting capability of the continuous-variable scheme turns out to be higher than that of its discrete-variable analogues.