ShantanuT01/DACTYL-Pretraining huggingface dataset:
The hard square lattice gas model on a square lattice is known to undergo a continuous phase transition from a low density fluid-like phase to high density phase with columnar or smectic order. We estimate the critical activity $z_c$ by calculating, within an approximation scheme, the interfacial tension between two differently ordered columnar phases, and then setting it to zero. The approximation scheme allows for the ordered phases to have multiple defects and the interface between the ordered phases to have overhangs. We estimate $z_c=105.35$, which is in good agreement with existing Monte Carlo simulation results of $z_c \approx 97.5$, and is an improvement over earlier best estimates of $z_c=54.87$ and $z_c=135.63$.
During the last decades, increasingly precise astronomical observations of the Galactic Centre (GC) region at radio, infrared, and X-ray wavelengths laid the foundations to a detailed understanding of the high energy astroparticle physics of this most remarkable location in the Galaxy. Recently, observations of this region in high energy (HE, 10 MeV - 100GeV) and very high energy (VHE, > 100 GeV) gamma rays added important insights to the emerging picture of the Galactic nucleus as a most violent and active region where acceleration of particles to very high energies -- possibly up to a PeV -- and their transport can be studied in great detail. Moreover, the inner Galaxy is believed to host large concentrations of dark matter (DM), and is therefore one of the prime targets for the indirect search for gamma rays from annihilating or decaying dark matter particles. In this article, the current understanding of the gamma-ray emission emanating from the GC is summarised and the results of recent DM searches in HE and VHE gamma rays are reviewed.
We investigated the quasi-periodic pulsation (QPP) in Lyman-alpha, X-ray and extreme-ultraviolet (EUV) emissions during two solar flares, i.e., an X-class (SOL2012-01-27T) and a C-class (SOL2016-02-08T). The full-disk Lyman-alpha and X-Ray flux during these solar flares were recorded by the EUV Sensor and X-Ray Sensor on board the Geostationary Operational Environmental Satellite. The {\deg}are regions were located from the EUV images measured by the Atmospheric Imaging Assembly. The QPP could be identified as a series of regular and periodic peaks in the light curves, and its quasi-periodicity was determined from the global wavelet and Fourier power spectra. A quasi-periodicity at about 3 minutes is detected during the impulsive phase of the X-class flare, which could be explained as the acoustic wave in the chromosphere (e.g., Milligan et al. 2017). Interestingly, a quasi-periodicity at roughly 1 minute is discovered during the entire evolutionary phases of solar flares, including the precursor, impulsive, and gradual phases. This is the first report of 1-minute QPP in the Lyman-alpha emission during solar flares, in particular during the flare precursor. It may be interpreted as a self-oscillatory regime of the magnetic reconnection, such as magnetic dripping.
Deep Convolutional Neural Networks have proven effective in solving the task of semantic segmentation. However, their efficiency heavily relies on the pixel-level annotations that are expensive to get and often require domain expertise, especially in medical imaging. Weakly supervised semantic segmentation helps to overcome these issues and also provides explainable deep learning models. In this paper, we propose a novel approach to the semantic segmentation of medical chest X-ray images with only image-level class labels as supervision. We improve the disease localization accuracy by combining three approaches as consecutive steps. First, we generate pseudo segmentation labels of abnormal regions in the training images through a supervised classification model enhanced with a regularization procedure. The obtained activation maps are then post-processed and propagated into a second classification model-Inter-pixel Relation Network, which improves the boundaries between different object classes. Finally, the resulting pseudo-labels are used to train a proposed fully supervised segmentation model. We analyze the robustness of the presented method and test its performance on two distinct datasets: PASCAL VOC 2012 and SIIM-ACR Pneumothorax. We achieve significant results in the segmentation on both datasets using only image-level annotations. We show that this approach is applicable to chest X-rays for detecting an anomalous volume of air in the pleural space between the lung and the chest wall. Our code has been made publicly available.
Given the extreme precision attainable with the Kepler Space Telescope, the mitigation of instrumental artefacts is very important. In an earlier paper (Murphy 2012), the characteristics of Kepler data were discussed in light of their effect on asteroseismology. We continue this discussion now that data processed with the new PDC-MAP pipeline are publicly available; users should use the latest data reductions available at the Mikulski Archive for Space Telescopes (MAST), not just for PDC, but also for improvements in the attached meta-data. We discuss the injection of noise in the frequency range 0-24 c/d (up to ~277 {\mu}Hz) by the PDC-LS pipeline into ~15 per cent of light-curves.
The pasta phase in core-collapse supernova matter (finite temperatures and fixed proton fractions) is studied within relativistic mean field models. Three different calculations are used for comparison, the Thomas-Fermi (TF), the Coexisting Phases (CP) and the Compressible Liquid Drop (CLD) approximations. The effects of including light clusters in nuclear matter and the densities at which the transitions between pasta configurations and to uniform matter occur are also investigated. The free energy, pressure, entropy and chemical potentials in the range of particle number densities and temperatures expected to cover the pasta region are calculated. Finally, a comparison with a finite temperature Skyrme-Hartree-Fock calculation is drawn.
Calculus via regularizations and rough paths are two methods to approach stochastic integration and calculus close to pathwise calculus. The origin of rough paths theory is purely deterministic, calculus via regularization is based on deterministic techniques but there is still a probability in the background. The goal of this paper is to establish a connection between stochastically controlled-type processes, a concept reminiscent from rough paths theory, and the so-called weak Dirichlet processes. As a by-product, we present the connection between rough and Stratonovich integrals for c{\`a}dl{\`a}g weak Dirichlet processes integrands and continuous semimartingales integrators.
Rotating Radio Transients (RRATs) represent a relatively new class of pulsar, primarily characterised by their sporadic bursting emission of single pulses on time scales of minutes to hours. In addition to the difficulty involved in detecting these objects, low-frequency ($<$300 MHz) observations of RRATs are sparse, which makes understanding their broadband emission properties in the context of the normal pulsar population problematic. Here, we present the simultaneous detection of RRAT J2325-0530 using the Murchison Widefield Array (154 MHz) and Parkes radio telescope (1.4 GHz). On a single-pulse basis, we produce the first polarimetric profile of this pulsar, measure the spectral index ($\alpha=-2.2\pm 0.1$), pulse energy distributions, and present the pulse rates in the context of detections in previous epochs. We find that the distribution of time between subsequent pulses is consistent with a Poisson process and find no evidence of clustering over the $\sim$1.5 hr observations. Finally, we are able to quantify the scintillation properties of RRAT J2325-0530 at 1.4 GHz, where the single pulses are modulated substantially across the observing bandwidth, and show that this characterisation is feasible even with irregular time sampling as a consequence of the sporadic emission behaviour.
Starting with the Dirac equation in the extreme Kerr metric we derive an integral representation for the propagator of solutions of the Cauchy problem with initial data in the class of smooth compactly supported functions.
We consider Rado numbers of the regular equations $\mathcal{E}(b)$ of the form \[ c_1x_1+c_2x_2+\dots+ c_{k-1}x_{k-1} = x_k + b, \] where $b \in \mathbb{Z}$ and $c_i \in \mathbb{Z}^{+}$ for all $i$. We give the upper bounds and the sufficient condition for the lower bounds for $t$-color Rado numbers $r(\mathcal{E}(b);t)$ in terms of $r(\mathcal{E}(0);t)$ for both $b>0$ and $b<0$. We also give examples where the exact values of Rado numbers are obtained from these results.
Graphene-metal contact resistance is governed by both intrinsic and extrinsic factors. Intrinsically, both the density of states bottleneck near the Dirac point and carrier reflection at the graphene-metal interface lead to a high contact resistance. Moreover, graphene exhibits insulating behavior for out-of-the-plane conduction. Extrinsically, surface contamination introduced by photoresist residue or different adsorbed species during standard lithography processing alters graphene's intrinsic properties by uncontrolled doping and increased scattering which results in high and inconsistent contact resistance. Here we demonstrate a femto-second laser assisted direct patterning of graphene microstructures that enables us to study both intrinsic and extrinsic effects on the graphene-metal interface. We show that a clean graphene-metal interface is not sufficient to obtain contact resistance approaching the intrinsic limit set by the quantum resistance. We also demonstrated that unlike CVD graphene, edge state conduction (or end-contact) is not spontaneously formed by metal deposition in case of graphene grown on SiC(0001). We conclude that for epitaxial graphene, intentional end-contact formation is necessary to obtain contact resistance near the quantum contact resistance limit.
The paper investigates a class of a semilinear wave equation with time-dependent damping term ($-\frac{1}{{(1+t)}^{\beta}}\Delta u_t$) and a nonlinearity $|u|^p$. We will show the influence of the the parameter $\beta$ in the blow-up results under some hypothesis on the initial data and the exponent $p$ by using the test function method. We also study the local existence in time of mild solution in the energy space $H^1(\mathbb{R}^n)\times L^2(\mathbb{R}^n)$.
Astrometry using H2O maser sources in star forming regions is expected to be a powerful tool to study the structures and dynamics of our Galaxy. Honma et al. (2007) (hereafter H2007) claimed that the annual parallax of S269 is determined within an error of 0.008 milliarcsec (mas), concluding that S269 is located at 5.3 kpc +- 0.2 kpc from the sun, and R= 13.1 kpc. They claimed that the rotational velocity of S269 is equal to that of the sun within a 3% error. This small error, however, is hardly understood when taking into account the results of other observations and theoretical studies of galactic dynamics. We here reanalyzed the VERA archival data using the self-calibration method (hybrid mapping), and found that clusters of maser features of S269 are distributed in much wider area than that investigated in H2007. We confirmed that, if we make a narrow region image without considering the presence of multiple maser spots, and only the phase calibration is applied, we can reproduce the same maser structures in H2007. The distribution extent of maser spots in the feature differs 0.2 mas from east to west between our results and H2007. Moreover, we found that change of relative positions of maser spots in the cluster reaches 0.1 mas or larger between observational epochs. This suggests that if one simply assumes the time-dependent, widely distributed maser sources as a stable single point source, it could cause errors of up to 0.1 mas in the annual parallax of S269. Taking into account the internal motions of maser spot clusters, the proper motion of S269 cannot be determined precisely. We estimated that the peculiar motion of S269 with respect to a Galactic circular rotation is ~20 km/s. These results imply that the observed kinematics of maser emissions in S269 cannot give a strong constraint on dynamics of the outer part of the Galaxy, in contrast to the claim by H2007.
We observed IGR J16194-2810 in the low/hard state with the Suzaku X-ray satellite in 2009. The source is a Symbiotic X-ray Binary (SyXB) classified as a category of a Low-Mass X-ray Binary (LMXB), since the system is composed of an M-type giant and probably a neutron star (NS). We detected the 0.8-50 keV signal with the XIS and HXD-PIN. The 2-10 keV luminosity was L ~ 7 x 10^34 erg s^-1 corresponding to ~10^-3 L_Edd, where L_Edd is the Eddington Luminosity of a 1.4 M_o NS and a source distance of 3.7 kpc is assumed. The luminosity is similar to those of past observations. The spectral analysis showed that there are two emission components below and above ~2 keV. The hard emission component is represented by a Comptonized black-body emission model with the seed-photon temperature ~1.0 keV and the emission radius ~700 m. The seed photon is considered to come from a small fraction of the NS surface. The soft component is reproduced by either a raw black-body (~0.4 keV, ~1.7 km) or a Comptonized emission (~0.1 keV, ~75 km). We think the origin is the emission from other part of the NS surface or the accreting stream. The physical parameters of the hard emission component of IGR J16194-2810 are compared with those of an SyXB (4U 1700+24) and LMXBs (Aql X-1 and 4U 0614+091). This comparison reveals that these SyXBs in the low/hard state have a smaller radiation region (< 1 km) on the NS surface with a higher seed-photon temperature (~1 keV) than the compared LMXBs.
We propose a new method for fitting the full-shape of the Lyman-$\alpha$ (Ly$\alpha$) forest three-dimensional (3D) correlation function in order to measure the Alcock-Paczynski (AP) effect. Our method preserves the robustness of baryon acoustic oscillations (BAO) analyses, while also providing extra cosmological information from a broader range of scales. We compute idealized forecasts for the Dark Energy Spectroscopic Instrument (DESI) using the Ly$\alpha$ auto-correlation and its cross-correlation with quasars, and show how this type of analysis improves cosmological constraints. The DESI Ly$\alpha$ BAO analysis is expected to measure $H(z_\mathrm{eff})r_\mathrm{d}$ and $D_\mathrm{M}(z_\mathrm{eff})/r_\mathrm{d}$ with a precision of $\sim0.9\%$ each, where $H$ is the Hubble parameter, $r_\mathrm{d}$ is the comoving BAO scale, $D_\mathrm{M}$ is the comoving angular diameter distance and the effective redshift of the measurement is $z_\mathrm{eff}\simeq2.3$. By fitting the AP parameter from the full shape of the two correlations, we show that we can obtain a precision of $\sim0.5-0.6\%$ on each of $H(z_\mathrm{eff})r_\mathrm{d}$ and $D_\mathrm{M}(z_\mathrm{eff})/r_\mathrm{d}$. Furthermore, we show that a joint full-shape analysis of the Ly$\alpha$ auto-correlation and its cross-correlation with quasars can measure the linear growth rate times the amplitude of matter fluctuations in spheres of $8\;h^{-1}$Mpc, $f\sigma_8(z_\mathrm{eff})$. Such an analysis could provide the first ever measurement of $f\sigma_8(z_\mathrm{eff})$ at redshift $z_\mathrm{eff}>2$. By combining this with the quasar auto-correlation in a joint analysis of the three high-redshift two-point correlation functions, we show that DESI could be able to measure $f\sigma_8(z_\mathrm{eff}\simeq2.3)$ with a precision of $5-12\%$, depending on the smallest scale fitted.
The now extinct 205Pb is a pure s-process radionuclide (t_{1/2} = 1.5x10^7 y) of possible substantial cosmochemical interest. As a necessary complement to the detailed theoretical study of the nuclear physics and astrophysics aspects of the 205Pb - 205Tl pair carried out by Yokoi et al. (1985), and to the recent calculation of the 205Pb production in Wolf-Rayet stars by Arnould et al. (1997), this paper addresses for the first time in some detail the question of the survival of this radionuclide in thermally pulsing AGB stars. This problem is made difficult by the high sensitivity to temperature and density of the rates of the weak interaction processes that are able to produce or destroy 205Pb. In view of this sensitivity, a recourse to detailed stellar models is mandatory. With the help of some simplifying assumptions concerning in particular the third dredge-up characteristics, some of which (like its depth) being considered as free parameters, predictions are made for the 205Pb contamination of the stellar surface at the end of a pulse-interpulse cycle following a series of a dozen of pulses in three different intermediate-mass stars (M=3M_sun,Z=0.02; M=6M_sun,Z=0.02; M=3M_sun,Z=0.001). It is concluded that the chances for a significant 205Pb surface enrichment are likely to increase with M for a given Z, or to increase with decreasing Z for a given M. More specifically, following the considered pulses at least, the enrichment appears to be rather unlikely in the 3M_sun star with Z=0.02, while it seems to be much more probable in the other two considered stars. It is also speculated that the (3M_sun,Z=0.02) star could possibly experience some 205Pb enrichment following later pulses than the ones considered in this paper.
This paper studies the relative spatial distribution of red-sequence and blue-cloud galaxies, and their relation to the dark matter distribution in the COMBO-17 survey as function of scale down to z~1. We measure the 2nd-order auto- and cross-correlation functions of galaxy clustering and express the relative biasing by using aperture statistics. Also estimated is the relation between the galaxies and the dark matter distribution exploiting galaxy-galaxy lensing (GGL). All observables are further interpreted in terms of a halo model. To fully explain the galaxy clustering cross-correlation function with a halo model, we need to introduce a new parameter,R, that describes the statistical relation between numbers of red and blue galaxies within the same halo. We find that red and blue galaxies are clearly differently clustered, a significant evolution of the relative clustering with redshift was not found. There is evidence for a scale-dependence of relative biasing. The relative clustering, the GGL and, with some tension, the galaxy numbers can be explained consistently within a halo model. For the cross-correlation function one requires a HOD variance that becomes Poisson even for relatively small occupancy numbers. For our sample, this rules out with high confidence a "Poisson satellite" scenario as found in semi-analytical models. Red galaxies have to be concentrated towards the halo centre, either by a central red galaxy or by a concentration parameter above that for dark matter.The value of R depends on the presence or absence of central galaxies: If no central galaxies or only red central galaxies are allowed, R is consistent with zero, whereas a positive correlation $R=+0.5\pm0.2$ is needed if both blue and red galaxies can have central galaxies.[ABRIDGED]
We review the present status of cosmological discoveries and how these confirm our modern cosmological model, but at the same time we try to focus on its weaknesses and inconsistencies with an historical perspective, and foresee how the on-going big cosmological projects may change in the future our view of the universe.
Adversarial domain adaptation has made impressive advances in transferring knowledge from the source domain to the target domain by aligning feature distributions of both domains. These methods focus on minimizing domain divergence and regard the adaptability, which is measured as the expected error of the ideal joint hypothesis on these two domains, as a small constant. However, these approaches still face two issues: (1) Adversarial domain alignment distorts the original feature distributions, deteriorating the adaptability; (2) Transforming feature representations to be domain-invariant needs to sacrifice domain-specific variations, resulting in weaker discriminability. In order to alleviate these issues, we propose category-invariant feature enhancement (CIFE), a general mechanism that enhances the adversarial domain adaptation through optimizing the adaptability. Specifically, the CIFE approach introduces category-invariant features to boost the discriminability of domain-invariant features with preserving the transferability. Experiments show that the CIFE could improve upon representative adversarial domain adaptation methods to yield state-of-the-art results on five benchmarks.
Fifth-order 1D nonlinear dispersion equations are shown to admit blow-up formation of shock waves as well as rarefaction waves. The concepts of smooth deformations are applied to distinguish "entropy" shocks from smooth rarefaction waves. Single point gradient catastrophe is shown to lead to nonuniqueness after blow-up.
We present spectral results from a multi-satellite, broad-band campaign on the Narrow-line Seyfert 1 galaxy Ton S180 performed at the end of 1999. We discuss the spectral-energy distribution of the source, combining simultaneous Chandra, ASCA and EUVE data with contemporaneous FUSE, HST, and ground-based optical and infra-red data. The resulting SED shows that most of the energy is emitted in the 10 -- 100 eV regime, which must be dominated by the primary energy source. No spectral turnover is evident in the UV regime. This, the strong soft X-ray emission, and the overall shape of the SED indicate that emission from the accretion disk peaks between 15 and 100 eV. High resolution FUSE spectra showing UV absorption due to O VI and the lack of detectable X-ray absorption in the Chandra spectrum demonstrate the presence of a low column density of highly ionized gas along our line-of-sight. The highly-ionized state of the circumnuclear gas is most likely linked to the high luminosity and steep spectrum of the active nucleus. Given the strong ionizing flux in Ton S180, it is possible that the clouds within a few tens of light days of the central source are too highly ionized to produce much line emission. Thus the narrow width of the emission lines in Ton S180 is due to the emission arising from large radii.
Young (125 Myr), populous ($>$1000 members), and relatively nearby, the Pleiades has provided an anchor for stellar angular momentum models for both younger and older stars. We used K2 to explore the distribution of rotation periods in the Pleiades. With more than 500 new periods for Pleiades members, we are vastly expanding the number of Pleiads with periods, particularly at the low mass end. About 92\% of the members in our sample have at least one measured spot-modulated rotation period. For the $\sim$8\% of the members without periods, non-astrophysical effects often dominate (saturation, etc.), such that periodic signals might have been detectable, all other things being equal. We now have an unusually complete view of the rotation distribution in the Pleiades. The relationship between $P$ and $(V-K_{\rm s})_0$ follows the overall trends found in other Pleiades studies. There is a slowly rotating sequence for $1.1\lesssim(V-K_{\rm s})_0\lesssim 3.7$, and a primarily rapidly rotating population for $(V-K_{\rm s})_0\gtrsim 5.0$. There is a region in which there seems to be a disorganized relationship between $P$ and $(V-K_{\rm s})_0$ for $3.7 \lesssim(V-K_{\rm s})_0\lesssim 5.0$. Paper II continues the discussion, focusing on multi-period structures, and Paper III speculates about the origin and evolution of the period distribution in the Pleiades.