ShantanuT01/DACTYL-Pretraining huggingface dataset:
We discuss our radio (Australia Telescope Compact Array and Australian Long Baseline Array) and X-ray (XMM-Newton) monitoring observations of the unusual ultraluminous supernova SN 1978K in NGC 1313 at ~25 years after the explosion. SN 1978K is a rare example of a Type IIn supernova that has remained bright enough to have long-term X-ray and radio observations. The observations probe the dense medium that was ejected by the progenitor star prior to its explosion; the star might have been a Luminous Blue Variable. The radio imaging shows that the source remains compact, but it may be marginally resolved. The radio monitoring shows deviations from a smooth decay suggesting that inhomogeneities are present in the radio emitting region. It appears that a major change occurred in the mass-loss rate of the progenitor star shortly before the supernova event. The X-ray emission between 2000 and 2006 is consistent with the radiation coming from two shocks. All the X-ray data can be fit using the same model (with no systematic evolution or short-term variability) but this has a surprising requirement: the X-ray emitting regions have a very large abundance of helium. This would be consistent with the X-ray emitting shocks being located in a helium-rich layer that was ejected by the progenitor star, or helium-rich material was ejected in the supernova explosion. The unusual properties of the supernova motivated a search for an associated gamma-ray burst (GRB). We show that SN 1978K was inside the ~4 sigma error box of GRB 771029. If this association is correct, the GRB was exceptionally underluminous. However, the quality of the gamma-ray burst locations at that time was poor, and this is likely just a chance alignment.
We implement a cluster-update Monte Carlo algorithm to simulate magnetic dipoles of the XY-spin type confined in a two-dimensional plane. The long-range character and anisotropy in the dipole interaction are handled by using the Luijten-Bl\"ote algorithm and the Dotsenko-Selke-Talapov algorithm, respectively. We have checked the performance of this cluster-update algorithm in comparison to the Metropolis algorithm and found that it equilibrated the system faster in terms of the number of flipped spins, although the overall computational complexity of the problem remained the same.
The AMS Collaboration has recently released precision data on cosmic ray (CR) leptons and protons at high energies. Interesting progresses have also been made on the measurement of CR nuclei, such as the boron-to-carbon ratio or the lithium spectrum, up to TeV/nucleon energies. In order to provide a description these data, I consider a diffusion model of CR propagation which allows for latitudinal variations of the CR diffusion properties in the Galactic halo. I discuss the role of high-precision data on light CR nuclei in resolutely testing this model and the key propagation parameters.
Polysilicon fuses are one time programmable memory elements which allow the calibration of integrated circuits at wafer and package level. We present a zero dimensional lumped parameter model of the programming of fuses made from a combination of tungsten silicide and polycrystalline silicon. The components of the model are an electrical model, a thermal model and a flow model. The electrical model describes the temperature and geometry dependent resistance of the fuse. The thermal model describes the heating and melting of the fuse and its surroundings. The flow model describes the disconnection of the fuse by electromigration driven flow of silica. The model generates quantitatively accurate results and reproduces trends with applied voltage and fuse size.
The paper presents a model of the electrically actuated formation and rupture of the nanosized metal filament inside oxide matrix. NiO oxide is used as an example for this model of ReRAM operation.
We present early high resolution spectroscopic observations of the nova V1369 Cen. We have detected an absorption feature at 6695.6 \AA\, that we have identified as blue--shifted $^7$Li I $\lambda$6708 \AA. The absorption line, moving at -550 km/s, was observed in five high-resolution spectra of the nova obtained at different epochs. On the basis of the intensity of this absorption line we infer that a single nova outburst can inject in the Galaxy $M_{Li} =$ 0.3 - 4.8 $\times 10^{-10}$ M$_{\odot}$. Given the current estimates of Galactic nova rate, this amount is sufficient to explain the puzzling origin of the overabundance of Lithium observed in young star populations.
In this paper we are concerned with some $p$-Kirchhoff type problems involving sign-changing weight functions. We prove the existence of multiple positive solutions of the problem via the Nehari manifold approach.
We derive the improved estimators for general interactions and employ these for the continuous-time quantum Monte Carlo method. Using a worm algorithm we show how measuring higher-ordered correlators leads to an improved high-frequency behavior in irreducible quantities such as the one-particle self-energy or the irreducible two-particle vertex for non-density-density interactions. A good knowledge of the asymptotics of the two-particle vertex is essential for calculating non-local electronic correlations using diagrammatic extensions to the dynamical mean field theory as well as for calculating susceptibilities. We test our algorithm against analytic results for the multi-orbital atomic-limit and the Falicov-Kimball model.
We theoretically study the electronic structure of magic-angle twisted bilayer graphene with disordered moir\'e patterns. By using an extended continuum model incorporating non-uniform lattice distortion, we find that the local density of states of the flat band is hardly broadened, but splits into upper and lower subbands in most places. The spatial dependence of the splitting energy is almost exclusively determined by the local value of the effective vector potential induced by heterostrain, whereas the variation of local twist angle and local moir\'e period give relatively minor effects on the electronic structure. We explain the exclusive dependence on the local vector potential by a pseudo Landau level picture for the magic-angle flat band, and we obtain an analytic expression of the splitting energy as a function of the strain amplitude.
Spark plasma sintering (SPS) technique is applied in combination with hydrogen decrepitation process for the recycling of SmCo5 magnets. The SmCo5 magnets for recycling were first decrepitated by hydrogen gas of a pressure of 4 bar for 3 hours to produce decrepitated powder. This powder was then used to prepare isotropic sintered magnets using the SPS technique, by sintering at 800-1000 oC for 1 minute. Full densification of the SPS-ed magnets was possible at a temperature of 1000 oC. The sample sintered at 900 oC showed the best internal coercivity (jHc) of higher than 1500 kA/m with high remanence (Br) value of 0.47 T and energy product (BH(max)) of 43.4 kJ/m3. The properties of the SPS-ed sample sintered at 900 oC were compared with conventionally sintered (CVS-ed) sample prepared by using fresh SmCo5 powder. The results showed the improvement of the magnetic properties of the SPS-ed sample in comparison to the CVS-ed sample at room temperature, and the possibility to use the SPS-ed sample at high temperature of 180 oC, where the sample showed good magnetic properties of jHc of 1502 kA/m, Br of 0.44 T and BH(max) of 36.4 kJ/m3. The microstructure and X-ray diffraction patterns of the SPS-ed and the CVS-ed samples were studied; where the samples showed to basically consist of SmCo5 matrix phase with Sm2Co7 and Sm-oxides.
Using a nonlinear Schr\"{o}dinger equation for the wave function of all systems, continuous transitions between quantum and classical motions are demonstrated for (i) the double-slit set up, (ii) the 2D harmonic oscillator and (iii) the hydrogen-like atom, all of which are of empirical interest.
Thermodynamic properties as well as low-energy magnon excitations of $S=1$ honeycomb-layered Na$_3$Ni$_2$SbO$_6$ have been investigated by high-resolution dilatometry, static magnetisation, and high-frequency electron spin resonance studies in magnetic fields up to 16 T. At $T_{\rm N}$ = 16.5 K, there is a tricritical point separating two distinct antiferromagnetic phases AF1 and AF2 from the paramagnetic regime. In addition, our data imply short-range antiferromagnetic correlations at least up to $\sim 5\cdot T_{\rm N}$. Well below $T_{\rm N}$, the magnetic field $B_{\rm C1}\approx$ 9.5 T is needed to stabilize AF2 against AF1. The thermal expansion and magnetostriction anomalies at $T_{\rm N}$ and $B_{\rm C1}$ imply significant magnetoelastic coupling, both of which associated with a sign change of $\partial L/\partial B$. The transition at $B_{\rm C1}$ is associated with softening of the antiferromagnetic resonance modes observed in the electron spin resonance spectra. The anisotropy gap $\Delta = 360$ GHz implies considerable uniaxial anisotropy. We conclude the crucial role of axial anisotropy favoring the AF1 spin structure over the AF2 one. While the magnetostriction data disprove a simple spin-flop scenario at $B_{\rm C1}$, the nature of a second transition at $B_{\rm C2}\approx$ 13 T remains unclear. Both the sign of the magnetostriction and Gr\"uneisen analysis suggest the short-range correlations at high temperatures to be of AF2-type.
The physical origin of the near-ultraviolet MgII emission remains an under-explored domain, contrary to more typical emission lines detected in the spectra of star-forming galaxies. We explore the nebular and physical properties for a sample of 381 galaxies between 0.70 < z < 2.34 drawn from the MUSE Hubble Ultra Deep Survey. The spectra of these galaxies show a wide variety of profiles of the MgII 2796,2803 resonant doublet, from absorption to emission. We present a study on the main drivers for the detection of MgII emission in galaxy spectra. By exploiting photoionization models we verified that the emission-line ratios observed in galaxies with MgII in emission are consistent with nebular emission from HII regions. From a simultaneous analysis of MUSE spectra and ancillary HST information via spectral energy distribution (SED) fitting, we find that galaxies with MgII in emission have lower stellar masses, smaller sizes, bluer spectral slopes and lower optical depth than those with absorption. This leads us to suggest that MgII emission is a potential tracer of physical conditions not merely related to those of the ionized gas. We show that these differences in MgII emission/absorption can be explained in terms of a higher dust and neutral gas content in the interstellar medium (ISM) of galaxies showing MgII in absorption, confirming the extreme sensitivity of MgII to the presence of the neutral ISM. We conclude with an analogy between the MgII doublet and the Ly-alpha line, due to their resonant nature. Further investigations with current and future facilities, including JWST, are promising as the detection of MgII emission and its potential connection with Ly-alpha could provide new insights on the ISM content in the early Universe.
It has long been puzzling regarding the mechanism behind the nonlinearity of lattice thermal expansion at low temperatures despite modeling considerations from various perspectives in classical or quantum approximations. An analytical solution in terms of local bond average is presented herewith showing that the thermal expansion coefficient follows closely the specific heat of Debye approximation without the involvement of mode Gruneisen constant or the bulk modulus. Matching predictions to experimental observations using the Debye temperature and the atomic cohesive energy as input evidences that the current approach may represent the true situation of temperature induced lattice expansion though the exact form of phonon density of states need to be considered for further refinement.
We present a spin foam model in which the fundamental ``bubble amplitudes'' (the analog of the one-loop corrections in quantum field theory) are finite as the cutoff is removed. The model is a natural variant of the field theoretical formulation of the Barrett-Crane model. As the last, the model is a quantum BF theory plus an implementation of the constraint that reduces BF theory to general relativity. We prove that the fundamental bubble amplitudes are finite by constructing an upper bound, using certain inequalities satisfied by the Wigner (3n)j-symbols, which we derive in the paper. Finally, we present arguments in support of the conjecture that the bubble diagrams of the model are finite at all orders.
This paper is withdrawn. The current main theorem can be proved by using a simple field theory. The main theorem is to placed by another theorem, shortly.
We present ionized-gas (OIII) and stellar kinematics (velocities and velocity dispersions) for 30 nearly face-on spiral galaxies out to as much as three disk scale lengths (h_R). These data have been derived from PPak IFU spectroscopy (4980-5370A), observed at a mean resolution of R=7700 (sigma_inst=17km/s). These data are a fundamental product of our survey and will be used in companion papers to, e.g., derive the detailed (baryonic+dark) mass budget of each galaxy in our sample. Our presentation provides a comprehensive description of the observing strategy, data reduction, and analysis. Along with a clear presentation of the data, we demonstrate: (1) The OIII and stellar rotation curves exhibit a clear signature of asymmetric drift with a rotation difference that is 11% of the maximum rotation speed of the galaxy disk, comparable to measurements in the solar neighborhood in the Milky Way. (2) The e-folding length of the stellar velocity dispersion is two times h_R on average, as expected for a disk with a constant scale height and mass-to-light ratio, with a scatter that is notably smaller for massive, high-surface-brightness disks in the most luminous galaxies. (3) At radii larger than 1.5 h_R, the stellar velocity dispersion tends to decline slower than the best-fitting exponential function, which may be due to an increase in the disk mass-to-light ratio, disk flaring, or disk heating by the dark-matter halo. (4) A strong correlation exists between the central vertical stellar velocity dispersion of the disks and their circular rotational speed at 2.2 h_R, with a zero point indicating that galaxy disks are submaximal. Moreover, weak but consistent correlations exist such that disks with a fainter central surface brightness in bluer and less luminous galaxies of later morphological types are kinematically colder with respect to their rotational velocities.
We present a simple method of generating approximate synthetic halo catalogues: HALOGEN. This method uses a combination of $2^{nd}$-order Lagrangian Perturbation Theory (2LPT) in order to generate the large-scale matter distribution, analytical mass functions to generate halo masses, and a single-parameter stochastic model for halo bias to position haloes. HALOGEN represents a simplification of similar recently published methods.   Our method is constrained to recover the 2-point function at intermediate ($10Mpc/h<r<50Mpc/h$) scales, which we show is successful to within 2 per cent. Larger scales ($\sim100Mpc/h$) are reproduced to within 15 per cent. We compare several other statistics (e.g. power spectrum, point distribution function, redshift space distortions) with results from N-Body simulations to determine the validity of our method for different purposes. One of the benefits of HALOGEN is its flexibility, and we demonstrate this by showing how it can be adapted to varying cosmologies and simulation specifications.   A driving motivation for the development of such approximate schemes is the need to compute covariance matrices and study the systematic errors for large galaxy surveys, which requires thousands of simulated realisations. We discuss the applicability of our method in this context, and conclude that it is well suited to mass production of appropriate halo catalogues.   The code is publicly available at https://github.com/savila/halogen
The interplay between Mott and Anderson routes to localization in disordered interacting systems gives rise to different transitions and transport regimes. Here, we investigate the phase diagram at finite temperatures using dynamical mean field theory combined with typical medium theory, which is an effective theory of the Mott-Anderson metal-insulator transition. We mainly focus on the properties of the coexistence region associated with the Mott phase transition. For weak disorder, the coexistence region is found to be similar as in the clean case. However, as we increase disorder Anderson localization effects are responsible for shrinking the coexistence region and at sufficiently strong disorder (approximately equal to twice the bare bandwidth) it drastically narrows, the critical temperature abruptly goes to zero, and we observe a phase transition in the absence of a coexistence of the metallic and insulating phases. In this regime, the effects of interaction and disorder are found to be of comparable importance for charge localization.
We study the number $N\_n$ of open paths of length $n$ in supercritical oriented percolation on $\Zd \times \N$, with $d \ge 1$. We prove that on the percolation event $\{\inf N\_n\textgreater{}0\}$, $N\_n^{1/n}$ almost surely converges to a positive deterministic constant. We also study the existence of directional limits. The proof relies on the introduction of adapted sequences of regenerating times, on subadditive arguments and on the properties of the coupled zone in supercritical oriented percolation.
Parabolic $R$-polynomials were introduced by Deodhar as parabolic analogues of ordinary $R$-polynomials defined by Kazhdan and Lusztig. In this paper, we are concerned with the computation of parabolic $R$-polynomials for the symmetric group. Let $S_n$ be the symmetric group on $\{1,2,\ldots,n\}$, and let $S=\{s_i\,|\, 1\leq i\leq n-1\}$ be the generating set of $S_n$, where for $1\leq i\leq n-1$, $s_i$ is the adjacent transposition. For a subset $J\subseteq S$, let $(S_n)_J$ be the parabolic subgroup generated by $J$, and let $(S_n)^{J}$ be the set of minimal coset representatives for $S_n/(S_n)_J$. For $u\leq v\in (S_n)^J$ in the Bruhat order and $x\in \{q,-1\}$, let $R_{u,v}^{J,x}(q)$ denote the parabolic $R$-polynomial indexed by $u$ and $v$. Brenti found a formula for $R_{u,v}^{J,x}(q)$ when $J=S\setminus\{s_i\}$, and obtained an expression for $R_{u,v}^{J,x}(q)$ when $J=S\setminus\{s_{i-1},s_i\}$. We introduce a statistic on pairs of permutations in $(S_n)^J$ for $J=S\setminus\{s_{i-2},s_{i-1},s_i\}$. Then we give a formula for $R_{u,v}^{J,x}(q)$, where $J=S\setminus\{s_{i-2},s_{i-1},s_i\}$ and $i$ appears after $i-1$ in $v$. We also pose a conjecture for $R_{u,v}^{J,x}(q)$, where $J=S\setminus\{s_{k},s_{k+1},\ldots,s_i\}$ with $1\leq k\leq i\leq n-1$ and the elements $k+1,k+2,\ldots, i$ appear in increasing order in $v$.
By treating CP-violating interaction of the electroweak bubble wall as a perturbative term, chiral charge flux through the bubble wall is estimated. It is found that the absolute value of the flux $F_Q$ has a sharp peak at $m_0 \sim a \sim T$ with $F_Q/(u T^3) \sim 10^{-3}\, (Q_L-Q_R)\,\Delta \theta$. Here $m_0$ is the fermion mass, $1/a$ is the wall thickness, $T$ is the temperature at which the bubbles are growing, $u$ is the wall velocity, $Q_{L(R)}$ is the chiral charge of the relevant left(right)-handed fermion and $\Delta\theta$ is the measure of CP violation.
The theory of correlated electron systems is formulated in a form which allows to use as a reference point an ab initio band structure theory (AIBST). The theory is constructed in two steps. As a first step the total Hamiltonian is transformed into a correlated form. In order to elucidate the microscopical origin of the parameters of the periodical Hubbard-Anderson model (PHAM) the terms of the full Hamiltonian which have the operator structure of PHAM are separated. It is found that the matrix element of mixing interaction includes ion-configuration and number-of-particles dependent contributions from the Coulomb interaction. In a second step the diagram technique (DT) is developed by means of generalization of the Baym-Kadanoff method for correlated systems.
Federated learning allows distributed medical institutions to collaboratively learn a shared prediction model with privacy protection. While at clinical deployment, the models trained in federated learning can still suffer from performance drop when applied to completely unseen hospitals outside the federation. In this paper, we point out and solve a novel problem setting of federated domain generalization (FedDG), which aims to learn a federated model from multiple distributed source domains such that it can directly generalize to unseen target domains. We present a novel approach, named as Episodic Learning in Continuous Frequency Space (ELCFS), for this problem by enabling each client to exploit multi-source data distributions under the challenging constraint of data decentralization. Our approach transmits the distribution information across clients in a privacy-protecting way through an effective continuous frequency space interpolation mechanism. With the transferred multi-source distributions, we further carefully design a boundary-oriented episodic learning paradigm to expose the local learning to domain distribution shifts and particularly meet the challenges of model generalization in medical image segmentation scenario. The effectiveness of our method is demonstrated with superior performance over state-of-the-arts and in-depth ablation experiments on two medical image segmentation tasks. The code is available at "https://github.com/liuquande/FedDG-ELCFS".
Many learning-based approaches have difficulty scaling to unseen data, as the generality of its learned prior is limited to the scale and variations of the training samples. This holds particularly true with 3D learning tasks, given the sparsity of 3D datasets available. We introduce a new learning framework for 3D modeling and reconstruction that greatly improves the generalization ability of a deep generator. Our approach strives to connect the good ends of both learning-based and optimization-based methods. In particular, unlike the common practice that fixes the pre-trained priors at test time, we propose to further optimize the learned prior and latent code according to the input physical measurements after the training. We show that the proposed strategy effectively breaks the barriers constrained by the pre-trained priors and could lead to high-quality adaptation to unseen data. We realize our framework using the implicit surface representation and validate the efficacy of our approach in a variety of challenging tasks that take highly sparse or collapsed observations as input. Experimental results show that our approach compares favorably with the state-of-the-art methods in terms of both generality and accuracy.
With a view to a better understanding of the influence of atomic quantum delocalisation effects on the phase behaviour of water, path integral simulations have been undertaken for almost all of the known ice phases using the TIP4P/2005 model, in conjunction with the rigid rotor propagator proposed by Muser and Berne [Phys. Rev. Lett. 77, 2638 (1996)]. The quantum contributions then being known, a new empirical model of water is developed (TIP4PQ/2005) which reproduces, to a good degree, a number of the physical properties of the ice phases, for example densities, structure and relative stabilities.