ShantanuT01/DACTYL-Pretraining huggingface dataset:
The growing number of extragalactic high-energy (HE, E > 100 MeV) and very-high-energy (VHE, E > 100 GeV) gamma-ray sources that do not belong to the blazar class suggests that VHE gamma-ray production may be a common property of most radio-loud Active Galactic Nuclei (AGN). In a previous paper, we have investigated the signatures of Compton-supported pair cascades initiated by VHE gamma-ray absorption in monochromatic radiation fields, dominated by Ly-alpha line emission from the Broad Line Region. In this paper, we investigate the interaction of nuclear VHE gamma-rays with the thermal infrared radiation field from a circumnuclear dust torus. Our code follows the spatial development of the cascade in full 3-dimensional geometry. We provide a model fit to the broadband SED of the dust-rich, gamma-ray loud radio galaxy Cen A and show that typical blazar-like jet parameters may be used to model the broadband SED, if one allows for an additional cascade contribution to the Fermi gamma-ray emission.
In this paper I shall give the complete solution of the equations governing the bilateral birth and death process on path set $\mathbb{R}_q=\{q^n,\quad n\in\mathbb{Z}\}$ in which the birth and death rates $\lambda_n=q^{2\nu-2n}$ and $\mu_n=q^{-2n}$ where $0<q<1$ and $\nu>-1$ . The mathematical methods employed here are based on $q$-Bessel Fourier analysis.
Spectral measurements of the 21 cm monopole background have the promise of revealing the bulk energetic properties and ionization state of our universe from z ~ 6-30. Synchrotron foregrounds are orders of magnitude larger than the cosmological signal, and are the principal challenge faced by these experiments. While synchrotron radiation is thought to be spectrally smooth and described by relatively few degrees of freedom, the instrumental response to bright foregrounds may be much more complex. To deal with such complexities, we develop an approach that discovers contaminated spectral modes using spatial fluctuations of the measured data. This approach exploits the fact that foregrounds vary across the sky while the signal does not. The discovered modes are projected out of each line-of-sight of a data cube. An angular weighting then optimizes the cosmological signal amplitude estimate by giving preference to lower-noise regions. Using this method, we show that it is essential for the passband to be stable to at least ~10^{-4}. In contrast, the constraints on the spectral smoothness of the absolute calibration are mainly aesthetic if one is able to take advantage of spatial information. To the extent it is understood, controlling polarization to intensity leakage at the ~10^{-2} level will also be essential to rejecting Faraday rotation of the polarized synchrotron emission.
In this paper we develop a new technique to prove existence of solutions of Fokker-Planck equations on Hilbert spaces for Kolmogorov operators with non trace-class second order coefficients or equivalently with an associated stochastic partial differential equation (SPDE) with non trace-class noise. Applications include stochastic 2D and 3D-Navier-Stokes equations with non trace-class additive noise.
Following the discovery of the Kondo effect the bulk transport and magnetic behavior of the dilute magnetic alloys have been successfully described. In the last fifteen years new directions have been developed as the study of the systems of reduced dimensions and the artificial atoms so called quantum dots. In this review the first subject is reviewed starting with the scanning tunneling microscope (STM) study of a single magnetic impurity. The next subject is the reduction of the amplitude of the Kondo effect in samples of reduced dimension which was explained by the surface magnetic anisotropy which blocks the motion of the integer spin nearby the surface. The electron dephasing and energy relaxation experiments are discussed with the possible explanation including the surface anisotropy, where the situation in cases of integer and half-integer spins is very different. Finally, the present situation of the theory of dynamical structural defects is briefly presented which may lead to two-channel Kondo behavior.
Camera traps are crucial in biodiversity motivated studies, however dealing with large number of images while annotating these data sets is a tedious and time consuming task. To speed up this process, Machine Learning approaches are a reasonable asset. In this article we are proposing an easy, accessible, light-weight, fast and efficient approach based on our winning submission to the "Hakuna Ma-data - Serengeti Wildlife Identification challenge". Our system achieved an Accuracy of 97% and outperformed the human level performance. We show that, given relatively large data sets, it is effective to look at each image only once with little or no augmentation. By utilizing such a simple, yet effective baseline we were able to avoid over-fitting without extensive regularization techniques and to train a top scoring system on a very limited hardware featuring single GPU (1080Ti) despite the large training set (6.7M images and 6TB).
We investigate solid-on-solid models that belong to the Kardar-Parisi-Zhang (KPZ) universality class on substrates that expand laterally at a constant rate by duplication of columns. Despite the null global curvature, we show that all investigated models have asymptotic height distributions and spatial covariances in agreement with those expected for the KPZ subclass for curved surfaces. In $1+1$ dimensions, the height distribution and covariance are given by the GUE Tracy-Widom distribution and the Airy$_2$ process, instead of the GOE and Airy$_1$ foreseen for flat interfaces. These results imply that, when the KPZ class splits into the curved and flat subclasses, as conventionally considered, the expanding substrate may play a role equivalent to, or perhaps more important than the global curvature. Moreover, the translational invariance of the interfaces evolving on growing domains allowed us to accurately determine, in $2+1$ dimensions, the analogue of the GUE Tracy-Widom distribution for height distribution and that of the Airy$_2$ process for spatial covariance. Temporal covariance is also calculated and shown to be universal in each dimension and in each of the two subclasses. A logarithmic correction associated to the duplication of column is observed and theoretically elucidated. Finally, crossover between regimes with fixed-size and enlarging substrates is also investigated.
We develop a Hodge theoretic invariant for families of projective manifolds that measures the potential failure of an Arakelov-type inequality in higher dimensions, one that naturally generalizes the classical Arakelov inequality over regular quasi-projective curves. We show that for families of manifolds with ample canonical bundle this invariant is uniformly bounded. As a consequence we establish that such families over a base of arbitrary dimension verify the aforementioned Arakelov inequality, answering a question of Viehweg.
We explore the combination of the extended dynamical mean field theory (EDMFT) with the GW approximation (GWA); the former sums the local contributions to the self-energies to infinite order in closed form and the latter handles the non-local ones to lowest order. We investigate the different levels of self-consistency that can be implemented within this method by comparing to the exact QMC solution of a finite-size model Hamiltonian. We find that using the EDMFT solution for the local self-energies as input to the GWA for the non-local self-energies gives the best result.
It is shown by numerical simulation that classical charged tachyons have self-orbiting helical solutions in a narrow neighborhood of certain discrete values for the velocity when the electromagnetic interaction is described by Feynman-Wheeler electrodynamics. The force rapidly oscillates between attractive and repulsive as a function of velocity in this neighborhood. Causal electrodynamics is also considered, and in this case it is found that when the force is attractive the tachyon loses energy to radiation. Only certain narrow ranges of velocity give attractive forces, and a geometrical derivation of these special velocities is given. Possible implications of these results for hidden variable theories of quantum mechanics are conjectured.
The structure of Gamma-Ray Burst (GRB) jets impacts on their prompt and afterglow emission properties. Insights into the still unknown structure of GRBs can be achieved by studying how different structures impact on the luminosity function (LF): i) we show that low ($10^{46} < L_{\rm iso} < 10^{48}$ erg/s) and high (i.e. with $L_{\rm iso} > 10^{50}$ erg/s) luminosity GRBs can be described by a unique LF; ii) we find that a uniform jet (seen on- and off-axis) as well as a very steep structured jet (i.e. $\epsilon(\theta) \propto \theta^{-s}$ with $s > 4$) can reproduce the current LF data; iii) taking into account the emission from the whole jet (i.e. including contributions from mildly relativistic, off-axis jet elements) we find that $E_{\rm iso}(\theta_{\rm v})$ (we dub this quantity "apparent structure") can be very different from the intrinsic structure $\epsilon(\theta)$: in particular, a jet with a Gaussian intrinsic structure has an apparent structure which is more similar to a power law. This opens a new viewpoint on the quasi-universal structured jet hypothesis.
In this article, we construct a natural group homomorphism   $$ \psi: \text{Br}(f)\to H^{1}_{et}(S, f_{*}\mathcal{O}_{X}^{\times}/\mathcal{O}_{S}^{\times})$$ for a faithful affine map $f: X \to S$ of noetherian schemes. Here $\text{Br}(f)$ denotes the relative Brauer group of $f.$ We also discuss the behavior of Brauer groups for a subintegral map. Furthermore, we prove a relative version of Kummer's exact sequence.
We present simulation data of first-order isotropic-to-nematic transitions in lattice models of liquid crystals and locate the thermodynamic limit inverse transition temperature $\epsilon_\infty$ via finite-size scaling. We observe that the inverse temperature of the specific heat maximum can be consistently extrapolated to $\epsilon_\infty$ assuming the usual $\alpha / L^d$ dependence, with $L$ the system size, $d$ the lattice dimension and proportionality constant $\alpha$. We also investigate the quantity $\epsilon_{L,k}$, the finite-size inverse temperature where $k$ is the ratio of weights of the isotropic to nematic phase. For an optimal value $k = k_{\rm opt}$, $\epsilon_{L,k}$ versus $L$ converges to $\epsilon_\infty$ much faster than $\alpha/L^d$, providing an economic alternative to locate the transition. Moreover, we find that $\alpha \sim \ln k_{\rm opt} / {\cal L}_\infty$, with ${\cal L}_\infty$ the latent heat density. This suggests that liquid crystals at first-order IN transitions scale approximately as $q$-state Potts models with $q \sim k_{\rm opt}$.
We examine the vertical structure and equilibrium of the molecular gas layer in the galactic disk, measuring its scale height and velocity dispersion as a function of Galactic radius by modeling the CO emission at the tangent points. The model takes into account emission from a large path length along the line of sight, corresponding to an interval \Delta R ~ 200-400 pc; and is parametrized by the scale height of the gas, the centroid in z, the rotation velocity and the velocity dispersion. This model is then fit to the $^{12}CO$ survey of Knapp et al.(1985) to determine the best fit parameters. The reduced \chi^2 from fitting the models (considering only the photon statistics) range from 2 to 19. The main source of error is the `shot noise' due to the small number of clouds. Simulations using discrete molecular clouds are carried out to estimate the errors. The scale height of the molecular gas increases with radius. The velocity dispersion varies from ~ 2 km/s to 11 km/s with a typical uncertainty of ~3 km/s and shows a monotonic increase with galactic radius. The midplane mass density of the disk calculated from the scale-height and velocity dispersion is consistent with the local value \rho_0(R_0) of 0.2 \msun pc^{-3}.
The scalar mode polarization of the cosmic microwave background is derived in a spatially closed universe from the Boltzmann equation using the line of sight integral method. The EE and TE multipole coefficients have been extracted analytically by considering some tolerable approximations such as considering the evolution of perturbation hydrodynamically and sudden transition from opacity to transparency at the time of last scattering. As the major advantage of analytic expressions, EE and TE multipole coefficients explicitly show the dependencies on baryon density, matter density, curvature, primordial spectral index, primordial power spectrum amplitude, Optical depth, recombination width and recombination time. Using a realistic set of cosmological parameters taken from a fit to data from Planck, the closed universe EE and TE power spectrums in the scalar mode are compared with numerical results from the CAMB code and also latest observational data. The analytic results agree with the numerical ones on the big and moderate scales. The peak positions are in good agreement with the numerical result on these scales while the peak heights agree with that to within 20% due to the approximations have been considered for these derivations. Also, several interesting properties of CMB polarization are revealed by the analytic spectra.
The relation between finite isokinetic thermostats and infinite Hamiltonian thermostats is studied and their equivalence is heuristically discussed.
Photo-assisted transport through a mesoscopic conductor occurs when an oscillatory (AC) voltage is superposed to the constant (DC) bias which is imposed on this conductor. Of particular interest is the photo assisted shot noise, which has been investigated theoretically and experimentally for several types of samples. For DC biased conductors, a detection scheme for finite frequency noise using a dissipative resonant circuit, which is inductively coupled to the mesoscopic device, was developped recently. We argue that the detection of the finite frequency photo-assisted shot noise can be achieved with the same setup, despite the fact that time translational invariance is absent here. We show that a measure of the photo-assisted shot noise can be obtained through the charge correlator associated with the resonant circuit, where the latter is averaged over the AC drive frequency. We test our predictions for a point contact placed in the fractional quantum Hall effect regime, for the case of weak backscattering. The Keldysh elements of the photo-assisted noise correlator are computed. For simple Laughlin fractions, the measured photo-assisted shot noise displays peaks at the frequency corresponding to the DC bias voltage, as well as satellite peaks separated by the AC drive frequency.
We present the class of models of a nonmagnetic impurity in S=1/2 generalized ladder with an AKLT-type valence bond ground state, and of a S=1/2 impurity in the S=1 AKLT chain. The ground state in presence of impurity can be found exactly. Recently studied phenomenon of local enhancement of antiferromagnetic correlations around the impurity is absent for this family of models.
Herwig 7 is a general-purpose Monte Carlo generator of particle collisions comprising both hard perturbative as well as soft phenomenological physics. Herwig is therefore capable to describe the entire final state of hadronized particles in a collision event. A spacetime topology of a parton system entering hadronization is fully described and tested for the first time. A combination of information from particles momenta and spacetime positions is utilized to minimize a boost-invariant distance measure of the parton system. We present a reasonable agreement of the model with a selection of experimental data and conclude that spacetime event topology can be meaningfully used in the further development.
We present the tomographic cross-correlation between galaxy lensing measured in the Kilo Degree Survey (KiDS-450) with overlapping lensing measurements of the cosmic microwave background (CMB), as detected by Planck 2015. We compare our joint probe measurement to the theoretical expectation for a flat $\Lambda$CDM cosmology, assuming the best-fitting cosmological parameters from the KiDS-450 cosmic shear and Planck CMB analyses. We find that our results are consistent within $1\sigma$ with the KiDS-450 cosmology, with an amplitude re-scaling parameter $A_{\rm KiDS} = 0.86 \pm 0.19$. Adopting a Planck cosmology, we find our results are consistent within $2\sigma$, with $A_{\it Planck} = 0.68 \pm 0.15$. We show that the agreement is improved in both cases when the contamination to the signal by intrinsic galaxy alignments is accounted for, increasing $A$ by $\sim 0.1$. This is the first tomographic analysis of the galaxy lensing -- CMB lensing cross-correlation signal, and is based on five photometric redshift bins. We use this measurement as an independent validation of the multiplicative shear calibration and of the calibrated source redshift distribution at high redshifts. We find that constraints on these two quantities are strongly correlated when obtained from this technique, which should therefore not be considered as a stand-alone competitive calibration tool.
The power of solar acoustic waves is reduced inside sunspots mainly due to absorption, emissivity reduction, and local suppression. The coefficients of these power-reduction mechanisms can be determined by comparing time-distance cross-covariances obtained from sunspots and from the quiet Sun. By analyzing 47 active regions observed by SOHO/MDI without using signal filters, we have determined the coefficients of surface absorption, deep absorption, emissivity reduction, and local suppression. The dissipation in the quiet Sun is derived as well. All of the cross-covariances are width corrected to offset the effect of dispersion. We find that absorption is the dominant mechanism of the power deficit in sunspots for short travel distances, but gradually drops to zero at travel distances longer than about 6 degrees. The absorption in sunspot interiors is also significant. The emissivity-reduction coefficient ranges from about 0.44 to 1.00 within the umbra and 0.29 to 0.72 in the sunspot, and accounts for only about 21.5% of the umbra's and 16.5% of the sunspot's total power reduction. Local suppression is nearly constant as a function of travel distance with values of 0.80 and 0.665 for umbrae and whole sunspots respectively, and is the major cause of the power deficit at large travel distances.
We present a phenomenological Lagrangian and Poisson brackets for obtaining nondissipative hydrodynamic theory of supersolids. A Lagrangian is constructed on the basis of unification of the principles of non-equilibrium thermodynamics and classical field theory. The Poisson brackets, governing the dynamics of supersolids, are uniquely determined by the invariance requirement of the kinematic part of the found Lagrangian. The generalization of Lagrangian is discussed to include the dynamics of vortices. The obtained equations of motion do not account for any dynamic symmetry associated with Galilean or Lorentz invariance. They can be reduced to the original Andreev-Lifshitz equations if to require Galilean invariance. We also present a relativistic-invariant supersolid hydrodynamics, which might be useful in astrophysical applications.
Normal inverse Gaussian (NIG) process was introduced by Barndorff-Nielsen (1997) by subordinating Brownian motion with drift to an inverse Gaussian process. Increments of NIG process are independent and stationary. In this paper, we introduce dependence between the increments of NIG process, by subordinating fractional Brownian motion to an inverse Gaussian process and call it fractional normal inverse Gaussian (FNIG) process. The basic properties of this process are discussed. Its marginal distributions are scale mixtures of normal laws, infinitely divisible for the Hurst parameter 1/2<=H< 1 and are heavy tailed. First order increments of the process are stationary and possess long-range dependence (LRD) property. It is shown that they have persistence of signs LRD property also. A generalization of the FNIG process called n-FNIG process is also discussed which allows Hurst parameter H in the interval (n-1, n). Possible applications to mathematical finance and hydraulics are also pointed out
We study the energy transfer in the linear system $$ \begin{cases} \ddot u+u+\dot u=b\dot v\\ \ddot v+v-\epsilon \dot v=-b\dot u \end{cases} $$ made by two coupled differential equations, the first one dissipative and the second one antidissipative. We see how the competition between the damping and the antidamping mechanisms affect the whole system, depending on the coupling parameter $b$.
We examine the theoretical implications of a population of low-mass helium-core white dwarfs in globular clusters. In particular, we focus on the observed population in the core of NGC 6397, where several low-mass white dwarf canditates have been identified as ``non-flickerers'' by Cool and collaborators. Age and mass estimates from cooling models, combined with dynamical and evolutionary considerations, lead us to infer that the dark binary companions are C/O white dwarfs rather than neutron stars. Furthermore, we find that the progenitor binaries very likely underwent an exchange interaction within the last 1.e9 years. We examine the prospects for detecting a similar population in other globular clusters, with particular attention to the case of 47 Tuc.
The CMS experiment at the Large Hadron Collider has reported a 2.8$\sigma$ excess in the $(2e)(2jets)$ channel around 2.1 TeV. Interpretation of this data is reconsidered in terms of the production of a right-handed weak gauge boson, $W_R$, of the left-right symmetric model and in an $SO(10)$ grand unified theory abiding by the Extended Survival Hypothesis. The left-right symmetric model can be consistent with this excess if (a) the heavy right-handed neutrino has a mass near $W_R$, or (b) if $g_L \neq g_R$, or (c) the right-handed CKM matrix is nontrivial. Combinations of the above possibilities are also viable. A $W_R$ with a mass in the TeV region if embedded in $SO(10)$ is not compatible with $g_L = g_R$. Rather, it implies $0.64 \leq g_R/g_L \leq 0.78$. Further, a unique symmetry-breaking route -- the order being left-right discrete symmetry breaking first, followed by $SU(4)_C$ and finally $SU(2)_R$ -- to the standard model is picked out. The $L \leftrightarrow R$ discrete symmetry has to be broken at around $10^{16}$ GeV. The grand unification scale is pushed to $10^{18}$ GeV making the detection of proton decay in ongoing searches rather unlikely. The $SU(4)_C$ breaking scale can be at its allowed lower limit of $10^6$ GeV so that $n - \bar{n}$ oscillation or flavour changing processes such as $K_L \rightarrow \mu e$ and $B_{d,s} \rightarrow \mu e$ may be detectable. The Higgs scalar multiplets responsible for $SO(10)$ symmetry breaking at various stages are uniquely identified so long as one adheres to a minimalist principle. We also remark, {\em en passant}, about a partially unified Pati-Salam model.
We generalize a previously obtained result, for the case of a few other static hyperbolic universes with manifolds of nontrivial topology as spatial sections.