ShantanuT01/DACTYL-Pretraining huggingface dataset:
Several newly discovered very-high-energy (VHE; E > 100 GeV) gamma-ray sources in the Galaxy are thought to be associated with energetic pulsars. Among them, middle-aged (> 1E+4 yr) systems exhibit large centre-filled VHE nebulae, offset from the pulsar position, which result from the complex relationship between the pulsar wind and the surrounding medium, and reflect the past evolution of the pulsar. Imaging Atmospheric Cherenkov Telescopes (IACTs) have been successful in revealing extended emission from these sources in the VHE regime. Together with radio and X-ray observations, this observational window allows one to probe the energetics and magnetic field inside these large-scale nebulae. H.E.S.S., with its large field of view, angular resolution of < 0.1deg and unprecedented sensitivity, has been used to discover a large population of such VHE sources. In this paper, the H.E.S.S. data from the continuation of the Galactic Plane Survey (-80deg < l < 60deg, |b| < 3deg), together with the existing multi-wavelength observations, are used. A new VHE gamma-ray source was discovered at R.A. (J2000) = 13h56m00s, Dec. (J2000) = -64d30m00s with a 2' statistical error in each coordinate, namely HESS J1356-645. The source is extended, with an intrinsic Gaussian width of (0.20 +/- 0.02)deg. Its integrated energy flux between 1 and 10 TeV of 8E-12 erg cm-2 s-1 represents ~ 11% of the Crab Nebula flux in the same energy band. The energy spectrum between 1 and 20 TeV is well described by a power law dN/dE ~ E-Gamma with photon index Gamma = 2.2 +/- 0.2stat +/- 0.2sys. The inspection of archival radio images at three frequencies and the analysis of X-ray data from ROSAT/PSPC and XMM-Newton/MOS reveal the presence of faint non-thermal diffuse emission coincident with HESS J1356-645. HESS J1356-645 is most likely associated with the young and energetic pulsar PSR J1357-6429 (Abridged)
The Continuum Shell Model is an old but recently revived method that traverses the boundary between nuclear many-body structure and nuclear reactions. The method is based on the non-Hermitian energy-dependent effective Hamiltonian. The formalism, interpretation of solutions and practical implementation of calculations are discussed in detail. The results of the traditional shell model are fully reproduced for bound states; resonance parameters and cross section calculations are presented for decaying states. Particular attention is given to one- and two-nucleon reaction channels including sequential and direct two-body decay modes. New calculations of reaction cross sections and comparisons with experimental data for helium and oxygen isotope chains are presented.
We study the ground-state (gs) phase diagram of the frustrated spin-1/2 $J_{1}$--$J_{2}$ antiferromagnet with $J_{2}=\kappa J_1>0$ ($J_{1}>0$) on the honeycomb lattice, using the coupled-cluster method. We present results for the ground-state energy, magnetic order parameter and plaquette valence-bond crystal (PVBC) susceptibility. We find a paramagnetic PVBC phase for $\kappa_{c_1}<\kappa<\kappa_{c_2}$, where $\kappa_{c_1} \approx 0.207 \pm 0.003$ and $\kappa_{c_2} \approx 0.385 \pm 0.010$. The transition at $\kappa_{c_1}$ to the N\'{e}el phase seems to be a continuous deconfined transition (although we cannot exclude a very narrow intermediate phase in the range $0.21 \lesssim \kappa \lesssim 0.24$), while that at $\kappa_{c_2}$ is of first-order type to another quasiclassical antiferromagnetic phase that occurs in the classical version of the model only at the isolated and highly degenerate critical point $\kappa = 1/2$. The spiral phases that are present classically for all values $\kappa > 1/6$ are absent for all $\kappa \lesssim 1$.
We study the effect of thermal fluctuations on homogeneous infinite Bose-Einstein condensate with spin F=2 in the cyclic state, when atoms occupy three hyperfine states with $m_{F}=0, \pm 2$. We use both the approach of small-amplitude oscillations and mapping of our model on the sine-Gordon model. We show that thermal fluctuations lead to the existence of the rough phase in one- and two-dimensional systems, when presence of kinks is favorable. The structure and energy of a single kink are found. We also discuss the effect of thermal fluctuations on spin degrees of freedom in F=1 condensate.
From a family of L-functions with unitary symmetry, Hughes and Rudnick obtained results on the height of its lowest zero. We extend their results to other families of Lfunctions according to the type of symmetry coming from statistics for low-lying zeros.
The key success factor of the video deblurring methods is to compensate for the blurry pixels of the mid-frame with the sharp pixels of the adjacent video frames. Therefore, mainstream methods align the adjacent frames based on the estimated optical flows and fuse the alignment frames for restoration. However, these methods sometimes generate unsatisfactory results because they rarely consider the blur levels of pixels, which may introduce blurry pixels from video frames. Actually, not all the pixels in the video frames are sharp and beneficial for deblurring. To address this problem, we propose the spatio-temporal deformable attention network (STDANet) for video delurring, which extracts the information of sharp pixels by considering the pixel-wise blur levels of the video frames. Specifically, STDANet is an encoder-decoder network combined with the motion estimator and spatio-temporal deformable attention (STDA) module, where motion estimator predicts coarse optical flows that are used as base offsets to find the corresponding sharp pixels in STDA module. Experimental results indicate that the proposed STDANet performs favorably against state-of-the-art methods on the GoPro, DVD, and BSD datasets.
Metal-nanoclusters (NC), deposited by magnetron-based nanocluster source coupled with quadrupole mass filter (QMF) assembly having independent control over its size and density, are used in fabricating NC-based non-volatile memory (NVM) devices. The effect of diameter and density on the NVM charge storage characteristics are presented where Ag is used as the metal NC. The Ag-NC, sandwiched between HfO$_2$ tunnel and control oxides, is deposited by using the combination of the above two instruments. No annealing is performed at any stage of the device fabrication. The largest hysteresis loop area in the capacitance-voltage ($C-V$) characteristics of metal-oxide-semiconductor (MOS) characteristics is observed for a cluster density of 1 $\times$ 10$^{11}$ cm$^{-2}$. Further, an NC size dependent hysteresis loop area is observed with the MOS devices where the NC diameter is varied from 3 to 1.5 nm keeping the NC density at 1 $\times$ 10$^{11}$ cm$^{-2}$. The device performance is found to be improved with a reduction of the NC size and shows its best with the NC diameter of 1.5 nm. The storage time of the NVM devices also increases with the decrease in the NC diameter and exhibits their best performances for the NCs with a diameter of 1.5 nm.
We study the hadron-quark mixed phase, which may occur in the interior of neutron stars. The relativistic mean-field model is employed to describe the hadronic phase, while the Nambu--Jona-Lasinio model is used for the quark phase. We examine the effects of nuclear symmetry energy in the hadronic phase and repulsive vector interaction in the quark phase. For the treatment of hadron-quark mixed phase, we describe and compare four methods: (1) energy minimization method; (2) coexisting phases method; (3) Gibbs construction; and (4) Maxwell construction. The finite-size effects like surface and Coulomb energies are taken into account in the energy minimization and coexisting phases methods, which play a key role in determining the pasta configuration during the hadron-quark phase transition. It is found that massive neutron stars may contain hadron-quark pasta phases, but pure quark matter is unlikely to occur in the interior of neutron stars.
Phase stability of various phases of MX (M = Ti, Zr; X = C, N) at equilibrium and under pressure is examined based on first-principles calculations of the electronic and phonon structures. The results reveal that all B1 (NaCl-type) MX structures undergo a phase transition to the B2-structures under high pressure in agreement with the previous total-energy calculations. The B1-MX structures are dynamically stable under very high pressure (210-570 GPa). The pressure-induced B2 (CsCl-type) MC phases are dynamically unstable even at high pressures, and TiN and ZrN are found to crystallize with the B2-structure only at pressures above 55 GPa. The first-order B1-to-B2 phase transition in these nitrides is not related to the softening of phonon modes, and the dynamical instability of B2-MX is associated with a high density of states at the Fermi level.
We investigate dust obscuration as parameterised by the infrared excess IRX$\equiv$$L_{\rm IR}/L_{\rm UV}$ in relation to global galaxy properties, using a sample of $\sim$32$\,$000 local star-forming galaxies (SFGs) selected from SDSS, GALEX and WISE. We show that IRX generally correlates with stellar mass ($M_\ast$), star formation rate (SFR), gas-phase metallicity ($Z$), infrared luminosity ($L_{\rm IR}$) and the half-light radius ($R_{\rm e}$). A weak correlation of IRX with axial ratio (b/a) is driven by the inclination and thus seen as a projection effect.   By examining the tightness and the scatter of these correlations, we find that SFGs obey an empirical relation of the form $IRX$=$10^\alpha\,(L_{\rm IR})^{\beta}\,R_{\rm e}^{-\gamma}\,(b/a)^{-\delta}$ where the power-law indices all increase with metallicity. The best-fitting relation yields a scatter of $\sim$0.17$\,$dex and no dependence on stellar mass. Moreover, this empirical relation also holds for distant SFGs out to $z=3$ in a population-averaged sense, suggesting it to be universal over cosmic time. Our findings reveal that IRX approximately increases with $L_{\rm IR}/R_{\rm e}^{[1.3 - 1.5]}$ instead of $L_{\rm IR}/R_{\rm e}^{2}$ (i.e., surface density). We speculate this may be due to differences in the spatial extent of stars versus star formation and/or complex star-dust geometries. We conclude that not stellar mass but IR luminosity, metallicity and galaxy size are the key parameters jointly determining dust obscuration in SFGs.
We consider the Lame system of linear elasticity with periodically distributed inclusions whose elastic parameters have high contrast compared to the background media. We develop a unified method based on layer potential techniques to quantify three convergence results when some parameters of the elastic inclusions are sent to extreme values. More precisely, we study the incompressible inclusions limit where the bulk modulus of the inclusions tends to infinity, the soft inclusions limit where both the bulk modulus and the shear modulus tend to zero, and the hard inclusions limit where the shear modulus tends to infinity. Our method yields convergence rates that are independent of the periodicity of the inclusions array, and are sharper than some earlier results of this type. A key ingredient of the proof is the establishment of uniform spectra gaps for the elastic Neumann-Poincare operator associated to the collection of periodic inclusions that are independent of the periodicity.
Traditional hyperspectral unmixing methods neglect the underlying variability of spectral signatures often observed in typical hyperspectral images (HI), propagating these missmodeling errors throughout the whole unmixing process. Attempts to model material spectra as members of sets or as random variables tend to lead to severely ill-posed unmixing problems. Although parametric models have been proposed to overcome this drawback by handling endmember variability through generalizations of the mixing model, the success of these techniques depend on employing appropriate regularization strategies. Moreover, the existing approaches fail to adequately explore the natural multidimensinal representation of HIs. Recently, tensor-based strategies considered low-rank decompositions of hyperspectral images as an alternative to impose low-dimensional structures on the solutions of standard and multitemporal unmixing problems. These strategies, however, present two main drawbacks: 1) they confine the solutions to low-rank tensors, which often cannot represent the complexity of real-world scenarios; and 2) they lack guarantees that endmembers and abundances will be correctly factorized in their respective tensors. In this work, we propose a more flexible approach, called ULTRA-V, that imposes low-rank structures through regularizations whose strictness is controlled by scalar parameters. Simulations attest the superior accuracy of the method when compared with state-of-the-art unmixing algorithms that account for spectral variability.
We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the $\lambda\phi^4$ interaction. The effective Lagrangian for the description of such a system is obtained after dropping the terms responsible for the change of the total particle number. Reactions $\pi^+\pi^-\leftrightarrow\pi^0\pi^0$, which determine the isospin balance of the medium, are permitted. Within the self-consistent Hartree approximation we compute the effective pion mass, thermodynamic characteristics of the system and the variance of the particle number at temperatures above the critical point of the induced Bose-Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. We analyze conditions for the condensate formation in the process of thermalization of an initially non-equilibrium pion gas. The normalized variance of the particle number increases with a temperature decrease but remains finite in the critical point of the Bose-Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case. In the kinetic regime of the condensate formation the variance is shown to stay finite also.
We investigate the existence and local uniqueness of normalized $k$-peak solutions for the fractional Schr\"odinger equations with attractive interactions with a class of degenerated trapping potential with non-isolated critical points.   Precisely, applying the finite dimensional reduction method, we first obtain the existence of $k$-peak concentrated solutions and especially describe the relationship between the chemical potential $\mu$ and the attractive interaction $a$. Second, after precise analysis of the concentrated points and the Lagrange multiplier, we prove the local uniqueness of the $k$-peak solutions with prescribed $L^2$-norm, by use of the local Pohozaev identities, the blow-up analysis and the maximum principle associated to the nonlocal operator $(-\Delta)^s$. To our best knowledge, there is few results on the excited normalized solutions of the fractional Schr\"odinger equations before this present work. The main difficulty lies in the non-local property of the operator $(-\Delta)^s$. First, it makes the standard comparison argument in the ODE theory invalid to use in our analysis. Second, because of the algebraic decay involving the approximate solutions, the estimates, on the Lagrange multiplier for example, would become more subtle. Moreover,when studying the corresponding harmonic extension problem, several local Pohozaev identities are constructed and we have to estimate several kinds of integrals that never appear in the classic local Schr\"odinger problems.   In addition, throughout our discussion, we need to distinct the different cases of $p$, which are called respectively that the mass-subcritical, the mass-critical, and the mass-supercritical case, due to the mass-constraint condition. Another difficulty comes from the influence of the different degenerate rates along different directions at the critical points of the potential.
Let k be a field, and A a finite-dimensional k-algebra. Let d be an integer. Denote by Gr(d,A) the Grassmannian of d-subspaces of A (viewed as a k-vector space), and by GL_1(A) the algebraic k-group whose points are invertible elements of A. The group GL_1(A) acts naturally on Gr(d,A) (by the formula g.E=gE). The aim of this paper is to study some birational properties of this action. More precisely, let r be the gcd of d and dim(A). Under some hypothesis on A (satisfied if A/k is \'etale), I show that the variety Gr(d,A) is birationally and GL_1(A)-equivariantly isomorphic to the product of Gr(r,A) by a projective space (on which GL_1(A) acts trivially). By twisting, this result has some corollaries in the theory of central simple algebras. For instance, let B and C be two central simple algebras over k, of coprime degrees. Then the Severi-Brauer variety SB(B \otimes C) is birational to the product of SB(B) \times SB(C) by an affine space of the correct dimension. These corollaries are in the spirit of Krashen's generalized version of Amitsur's conjecture.
A hyperbolic relaxation of the classical Navier-Stokes problem in 2D bounded domain with Dirichlet boundary conditions is considered. It is proved that this relaxed problem possesses a global strong solution if the relaxation parameter is small and the appropriate norm of the initial data is not very large. Moreover, the dissipativity of such solutions is established and the singular limit as the relaxation parameter tends to zero is studied
An equation of state(EOS) of nuclear matter with explicit inclusion of a spin-isospin dependent force is constructed from a finite range, momentum and density dependent effective interaction. This EOS is found to be in good agreement with those obtained from more sophisticated models for unpolarised nuclear matter. Introducing spin degrees of freedom, it is found that at density about 2.5 times the density of normal nuclear matter the neutron matter undergoes a ferromagnetic transition. The maximum mass and the radius of the neutron star agree favourably with the observations. Since finding quark matter rather than spin polarised nuclear matter at the core of neutron stars is more probable, the proposed EOS is also applied to the study of hybrid stars. It is found using the bag model picture that one can in principle describe both the mass and size as well as the surface magnetic field of hybrid stars satisfactorily.
Interplay between Kondo effect and trends to antiferromagnetic and spin glass ordering in perfect and disordered bipartite Kondo lattices is considered. Ginzburg-Landau equation is derived from the microscopic effective action written in three mode representation (Kondo screening, antiferromagnetic correlations and spin liquid correlations). The problem of local constraint is resolved by means of Popov-Fedotov representation for localized spin operators. It is shown that the Kondo screening enhances the trend to a spin liquid crossover and suppresses antiferromagnetic ordering in perfect Kondo lattices and spin glass ordering in doped Kondo lattices. The modified Doniach's diagram is constructed, and possibilities of going beyond the mean field approximation are discussed.
We report on a quantum electrodynamic (QED) investigation of the interaction between a ground state atom with another atom in an excited state. General expressions, applicable to any atom, are indicated for the long-range tails which are due to virtual resonant emission and absorption into and from vacuum modes whose frequency equals the transition frequency to available lower-lying atomic states. For identical atoms, one of which is in an excited state, we also discuss the mixing term which depends on the symmetry of the two-atom wave function (these evolve into either the gerade or the ungerade state for close approach), and we include all nonresonant states in our rigorous QED treatment. In order to illustrate the findings, we analyze the fine-structure resolved van der Waals interaction for nD-1S hydrogen interactions with n=8,10,12 and find surprisingly large numerical coefficients.
We study existence problem for semilinear equations with Borel measure data and operator generated by a symmetric Markov semigroup. We assume merely that the nonlinear part satisfies the so-called sign condition. Using the method of sub and supersolutions we show the existence of maximal measure for which there exists a solution to the problem (the so-called reduced measure introduced by H. Brezis, M. Marcus and A.C. Ponce).
The extrapolation of small-cluster exact-diagonalization calculations is used to examine the possibility of electronic ferroelectricity in the one dimensional spinless and spin-one-half Falicov-Kimball model (FKM). It is found that neither spinless nor spin-one-half version of the FKM does not allow for a ferroelectric ground state with a spontaneous polarization, i.e. there is no nonvanishing $<d^{+}f>$-expectation value for vanishing hybridization $V$.
There is a huge demand to accurately determine the magneto-electrical properties of particles in the nano sized regime due to the modern IC technology revolution and biomedical application science. In this paper, we present a microwave waveguide measurement technique for complex permeability and permittivity of expensive nano sized magnetic powder materials. In the measurement process, Agilents 8510C vector network analyzer was used to have a standard TRL calibration for free space inside the waveguides. In order to maintain the recommended insertion phase range, a very thin prepared sample was loaded inside the calibrated waveguide. Also, the loaded materials magnetic and dielectric effects were considered into the cutoff wavelength of the propagation constant of the TE10 wave from the geometrical dimensions of the waveguides. This makes the measured permeability and permittivity more reliable than commonly used techniques. The six different compounds of nano sized ferrite powders (Fe3O4, CuFe2O4, CuFe2O4Zn, Fe2NiO3Zn, BaFe12O19, and SrFe12O19), in which the average diameter of nano particles is less than 40nm were purchased from Sigma-Aldrich, Inc for measurement purposes employing this technique. For industrial benefits, we present the complex permeability and permittivity on the frequency range from 3.95GHz to 5.85GHz. The measured results showed that the dielectric permittivity of these materials is quite different from those of solid state materials. Index Terms, Nano ferrites, waveguide technique, permeability, permittivity.
The direct collapse (DC) is a promising mechanism that provides massive seed black holes (BHs) with $\sim 10^{5}~M_{\odot}$ in the early universe. To study a long-term accretion growth of a DCBH thus formed, we perform cosmological radiation-hydrodynamics simulations, extending our previous work where we investigated its formation stage. With a high spatial resolution down below the Bondi radius, we show that the accretion rate onto the BH is far below the Eddington value. Such slow mass growth is partly because of the strong radiative feedback from the accreting BH. Moreover, we find that the BH has a large velocity of $\sim 100~{\rm km~s^{-1}}$ relative to the gas after it falls into the first galaxy, which substantially reduces the accretion rate. The latter effect stems from the fact that the DCBHs form in metal-free environments typically at $\sim 1~$kpc from the galaxy. The BH accelerates as it approaches the galactic center due to the gravity. The relative velocity never damps after that, and the BH does not settle down to the galactic center but continues to wander around it. An analytic estimate predicts that the DCBH formation within $\sim 100$~pc around the galactic center is necessary to decelerate the BH with dynamical friction before $z=7$. Since metal enrichment with $Z \sim 10^{-5} - 10^{-3}~Z_\odot$ is expected in such a case, the formation of DCBHs in the metal-poor environments is preferable for the subsequent rapid growth.