ShantanuT01/DACTYL-Pretraining huggingface dataset:
A simple theoretical solution to the design of a control field that generates complete population transfer from an initial state, via $N$ nondegenerate intermediate states, to one arbitrary member of $M$ ($M\leq N$) degenerate states is constructed. The full control field exploits an $(M+N-1)$-node null adiabatic state, created by designing the relative phases and amplitudes of the component fields that together make up the full field. The solution found is universal in the sense that it does not depend on the exact number of the unwanted degenerate states or their properties. The results obtained suggest that a class of multi-level quantum systems with degenerate states can be completely controllable, even under extremely strong constraints, e.g., never populating a Hilbert subspace that is only a few dimensions smaller than the whole Hilbert space.
Our findings show that the hardness of glass-like B2O3 is of about 1.5 GPa, while the hardness of the high-pressure phase is higher by a factor of 10 (16(5) GPa) and comparable with the hardness (16 GPa) of the WC-10% Co hard alloy.
Automatic segmentation of abdomen organs using medical imaging has many potential applications in clinical workflows. Recently, the state-of-the-art performance for organ segmentation has been achieved by deep learning models, i.e., convolutional neural network (CNN). However, it is challenging to train the conventional CNN-based segmentation models that aware of the shape and topology of organs. In this work, we tackle this problem by introducing a novel end-to-end shape learning architecture -- organ point-network. It takes deep learning features as inputs and generates organ shape representations as points that located on organ surface. We later present a novel adversarial shape learning objective function to optimize the point-network to capture shape information better. We train the point-network together with a CNN-based segmentation model in a multi-task fashion so that the shared network parameters can benefit from both shape learning and segmentation tasks. We demonstrate our method with three challenging abdomen organs including liver, spleen, and pancreas. The point-network generates surface points with fine-grained details and it is found critical for improving organ segmentation. Consequently, the deep segmentation model is improved by the introduced shape learning as significantly better Dice scores are observed for spleen and pancreas segmentation.
We report on the results from a large observational campaign on the bare Seyfert galaxy Ark 120, jointly carried out in 2014 with XMM-Newton, Chandra, and NuSTAR. The fortunate line of sight to this source, devoid of any significant absorbing material, provides an incomparably clean view to the nuclear regions of an active galaxy. Here we focus on the analysis of the iron fluorescence features, which form a composite emission pattern in the 6$-$7 keV band. The prominent K$\alpha$ line from neutral iron at 6.4 keV is resolved in the Chandra High-Energy Transmission Grating spectrum to a full-width at half maximum of 4700$^{+2700}_{-1500}$ km s$^{-1}$, consistent with an origin from the optical broad-line region. Excess components are detected on both sides of the narrow K$\alpha$ line: the red one (6.0$-$6.3 keV) clearly varies in strength in about one year, and hints at the presence of a broad, mildly asymmetric line from the accretion disk; the blue one (6.5$-$7.0 keV), instead, is likely a blend of different contributions, and appears to be constant when integrated over long enough exposures. However, the Fe K excess emission map computed over the 7.5 days of the XMM-Newton monitoring shows that both the red and the blue features are actually highly variable on timescales of $\sim$10$-$15 hours, suggesting that they might arise from short-lived hotspots on the disk surface, located within a few tens of gravitational radii from the central supermassive black hole and possibly illuminated by magnetic reconnection events. Any alternative explanation would still require a highly dynamic, inhomogeneous disk/coronal system, involving clumpiness and/or instability.
In this paper we study the deterministic and stochastic homogenisation of free-discontinuity functionals under \emph{linear} growth and coercivity conditions. The main novelty of our deterministic result is that we work under very general assumptions on the integrands which, in particular, are not required to be periodic in the space variable. Combining this result with the pointwise Subadditive Ergodic Theorem by Akcoglu and Krengel, we prove a stochastic homogenisation result, in the case of stationary random integrands. In particular, we characterise the limit integrands in terms of asymptotic cell formulas, as in the classical case of periodic homogenisation.
We examine the cosmological information available from the 1-point probability distribution (PDF) of the weak-lensing convergence field, utilizing fast L-PICOLA simulations and a Fisher analysis. We find competitive constraints in the $\Omega_m$-$\sigma_8$ plane from the convergence PDF with $188\ arcmin^2$ pixels compared to the cosmic shear power spectrum with an equivalent number of modes ($\ell < 886$). The convergence PDF also partially breaks the degeneracy cosmic shear exhibits in that parameter space. A joint analysis of the convergence PDF and shear 2-point function also reduces the impact of shape measurement systematics, to which the PDF is less susceptible, and improves the total figure of merit by a factor of $2-3$, depending on the level of systematics. Finally, we present a correction factor necessary for calculating the unbiased Fisher information from finite differences using a limited number of cosmological simulations.
We demonstrate an equivalence between the wave equation obeyed by the entanglement entropy of CFT subregions and the linearized bulk Einstein equation in Anti-de Sitter pace. In doing so, we make use of the formalism of kinematic space [arXiv:1505.05515] and fields on this space, introduced in [arXiv:1604.03110]. We show that the gravitational dynamics are equivalent to a gauge invariant wave-equation on kinematic space and that this equation arises in natural correspondence to the conformal Casimir equation in the CFT.
Using a collapsing matter model at the center of an expanding universe as described by Weinberg we assume a special type of generated pressure. This pressure transmits into the surrounding expanding universe. Under certain restriction the ensuing hubble parameter is positive. The deacceleration parameter fluctuates with time, indicating that the universe accelerates for certain time and decelerates for other time intervals.
We study thermal transport in anisotropic Heisenberg spin chains using the quantum master equation. It is found that thermal rectification changes sign when the external homogeneous magnetic field is varied. This reversal also occurs when the magnetic field becomes inhomogeneous. Moreover, we can tune the reversal of rectification by temperatures of the heat baths, the anisotropy and size of the spin chains.
We study the assembly of globular clusters (GCs) in 9 galaxy clusters using the cosmological simulation Illustris. GCs are tagged to individual galaxies at their infall time. The tidal removal of GCs from their galaxies and the distribution of the GCs within the cluster is later followed self-consistently by the simulation. The method relies on the simple assumption of a single power-law relation between halo mass (M_vir) and mass in GCs (M_GC) as found in observations. We find that the GCs specific frequency $S_N$ as a function of V-band magnitude naturally reproduces the observed "U"-shape, due to the combination of a power law M_GC-M_vir relation and the non-linear M_*-M_vir relation from the simulation. Additional scatter in the $S_N$ values are traced back to galaxies with early infall times due to the evolution in the M_*-M_vir relation with redshift. GCs that have been tidally removed from their galaxies form today the intra-cluster component from which about ~60% were brought in by galaxies that orbit today within the cluster potential. The remaining "orphan" GCs are contributed by satellite galaxies with a wide range of stellar masses that are fully tidally disrupted at z=0. This intra-cluster component is a good dynamical tracer of the dark matter potential. As a consequence of the accreted nature of most intra-cluster GCs, their orbits are fairly radial with a predicted orbital anisotropy \beta >= 0.5. However, local tangential motions may appear as a consequence of localized substructure, providing a possible interpretation to the \beta<0 values suggested in observations of M87.
We study more deeply the sensitivity of the $ZH$ production process in gluon-gluon collisions to the details of a possible Higgs and top quark compositeness. We establish a relation between Higgs and top quark form factors which would keep the basic cancellation appearing in SM and satisfy the concept of CSM. We give illustrations showing the spectacular consequences of various choices preserving or violating this CSM constraint.
We continue our investigation of an improved quantization scheme for spherically symmetric loop quantum gravity. We find that in the region where the black hole singularity appears in the classical theory, the quantum theory contains semi-classical states that approximate general relativity coupled to an effective anisotropic fluid. The singularity is eliminated and the space-time can be continued into a white hole space-time. This is similar to previously considered scenarios based on a loop quantum gravity quantization.
In the previous work, it was shown that, in supersymmetric (matrix) discretized quantum mechanics, inclusion of an external field twisting the boundary condition of fermions enables us to discuss spontaneous breaking of supersymmetry (SUSY) in the path-integral formalism in a well-defined way. In the present work, we continue investigating the same systems from the points of view of localization and Nicolai mapping. The localization is studied by changing of integration variables in the path integral, which is applicable whether or not SUSY is explicitly broken. We examine in detail how the integrand of the partition function with respect to the integral over the auxiliary field behaves as the auxiliary field vanishes, which clarifies a mechanism of the localization. In SUSY matrix models, we obtain a matrix-model generalization of the localization formula. In terms of eigenvalues of matrix variables, we observe that eigenvalues' dynamics is governed by balance of attractive force from the localization and repulsive force from the Vandermonde determinant. The approach of the Nicolai mapping works even in the presence of the external field. It enables us to compute the partition function of SUSY matrix models for finite N (N is the rank of matrices) with arbitrary superpotential at least in the leading nontrivial order of an expansion with respect to the small external field. We confirm the restoration of SUSY in the large-N limit of a SUSY matrix model with a double-well scalar potential observed in the previous work.
We review recent results on the tidal structures of spiral galaxies. Topics included are general characteristics of tails; kinematics of tidal structures and dark haloes of host galaxies; frequency of tidal distortions at z~1.
We prove that a differential field K is algebraically closed and Picard-Vessiot closed if and only if the differential Galois cohomology group H^1_\partial(K,G) is trivial for any linear differential algebraic group G over K. We give an application to the parameterized Picard-Vessiot theory.
The spectral theorem of many-body Green's function theory relates thermodynamic correlations to Green's functions. More often than not, the matrix governing the equations of motion has zero eigenvalues. In this case, the standard text-book approach requires both commutator and anti-commutator Green's functions to obtain equations for that part of the correlation which does not lie in the null space of the matrix. In this paper, we show that this procedure fails if the projector onto the null space is dependent on the momentum vector. We propose an alternative formulation of the theory in terms of the non-null space alone and we show that a solution is possible if one can find a momentum-independent projector onto some subspace of the non-null space. To do this, we enlist the aid of the singular value decomposition (SVD) of the equation of motion matrix in order to project out the null space, thus reducing the size of the matrix and eliminating the need for the anti-commutator Green's function. We extend our previous work, dealing with a ferromagnetic Heisenberg monolayer and a momentum-independent projector onto the null space, where both multilayer films and a momentum-dependent projector are considered. We develop the numerical methods capable of handling these cases and offer a computational algorithmus that should be applicable to any similar problem arising in Green's function theory.
We study the fragmentation of a transversely polarized quark into a non collinear (k_T not= 0) spinless hadron and the fragmentation of an unpolarized quark into a non collinear transversely polarized spin 1/2 baryon. These nonperturbative properties are described by spin and k_T dependent fragmentation functions and are revealed in the observation of single spin asymmetries. Recent data on the production of pions in polarized semi-inclusive DIS and long known data on Lambda polarization in unpolarized p-N processes are considered: these new fragmentation functions can describe the experimental results and the single spin effects in the quark fragmentation turn out to be surprisingly large.
We present Atacama Large Millimeter/submillimeter Array observations of the brightest cluster galaxy Hydra-A, a nearby ($z=0.054$) giant elliptical galaxy with powerful and extended radio jets. The observations reveal CO(1-0), CO(2-1), $^{13}$CO(2-1), CN(2-1), SiO(5-4), HCO$^{+}$(1-0), HCO$^{+}$(2-1), HCN(1-0), HCN(2-1), HNC(1-0) and H$_{2}$CO(3-2) absorption lines against the galaxy's bright and compact active galactic nucleus. These absorption features are due to at least 12 individual molecular clouds which lie close to the centre of the galaxy and have velocities of approximately $-50$ to $+10$ km/s relative to its recession velocity, where positive values correspond to inward motion. The absorption profiles are evidence of a clumpy interstellar medium within brightest cluster galaxies composed of clouds with similar column densities, velocity dispersions and excitation temperatures to those found at radii of several kpc in the Milky Way. We also show potential variation in a $\sim 10$ km/s wide section of the absorption profile over a two year timescale, most likely caused by relativistic motions in the hot spots of the continuum source which change the background illumination of the absorbing clouds.
We report the discovery of GeV emission at the position of supernova remnant Kes 17 by using the data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Kes 17 can be clearly detected with a significance of ~12 sigma in the 1 - 20 GeV range. Moreover, a number of gamma-ray sources were detected in its vicinity. The gamma-ray spectrum of Kes 17 can be well described by a simple power-law with a photon index of ~ 2.4. Together with the multi-wavelength evidence for its interactions with the nearby molecular cloud, the gamma-ray detection suggests that Kes 17 is a candidate acceleration site for cosmic-rays.
In this article, we first review the connection between L\'evy processes and infinitely divisible random variables, and the classification of infinitely divisible distributions. Using this connection and the L\'evy-Khinchine representation of the characteristic function, we establish a Stein identity for an infinitely divisible random variable. The classification and slight modification in approach give us a Stein identity for an $\alpha$-stable random variable with $\alpha\in (0,2).$ Using fine regularity estimates for the solution to Stein equation, we derive error bounds for $\alpha$-stable approximations. We then apply these results to obtain rates of convergence. Finally, we compare these rates with the results available in the literature.
We report observations of tunneling anisotropic magnetoresitance (TAMR) in vertical tunnel devices with a ferromagnetic multilayer-(Co/Pt) electrode and a non-magnetic Pt counter-electrode separated by an AlOx barrier. In stacks with the ferromagnetic electrode terminated by a Co film the TAMR magnitude saturates at 0.15% beyond which it shows only weak dependence on the magnetic field strength, bias voltage, and temperature. For ferromagnetic electrodes terminated by two monolayers of Pt we observe order(s) of magnitude enhancement of the TAMR and a strong dependence on field, temperature and bias. Discussion of experiments is based on relativistic ab initio calculations of magnetization orientation dependent densities of states of Co and Co/Pt model systems.
We study the ``flat'' directions of non-BPS extremal black hole attractors for N=2, d=4 supergravities whose vector multiplets' scalar manifold is endowed with homogeneous symmetric special Kahler geometry. The non-BPS attractors with non-vanishing central charge have a moduli space described by real special geometry (and thus related to the d=5 parent theory), whereas the moduli spaces of non-BPS attractors with vanishing central charge are certain Kahler homogeneous symmetric manifolds. The moduli spaces of the non-BPS attractors of the corresponding N=2, d=5 theories are also indicated, and shown to be rank-1 homogeneous symmetric manifolds.
Our Swift monitoring program triggered two joint XMM-Newton, NuSTAR and HST observations on 11 and 21 December 2016 targeting NGC 3783, as its soft X-ray continuum was heavily obscured. Consequently, emission features, including the O VII radiative recombination continuum, stand out above the diminished continuum. We focus on the photoionized emission features in the December 2016 RGS spectra and compare them to the time-averaged RGS spectrum obtained in 2000--2001 when the continuum was unobscured. A two-phase photoionized plasma is required to account for the narrow emission features. These narrow emission features are weakly varying between 2000--2001 and December 2016. We also find a statistically significant broad emission component in the time-averaged RGS spectrum in 2000--2001. This broad emission component is significantly weaker in December 2016, suggesting that the obscurer is farther away than the X-ray broad-line region. In addition, by analyzing the archival high-resolution X-ray spectra, we find that nine photoionized absorption components with different ionization parameters and kinematics are required for the warm absorber in X-rays.
We consider the effects of the electron-electron interaction in a clean Dirac metal, i.e., a Dirac system with the chemical potential not tuned to the Dirac point. We introduce the notion of a Dirac Fermi liquid (DFL) and discuss the soft two-particle excitations in such systems, which are qualitatively different from the corresponding excitations in a conventional, or Landau, Fermi liquid (LFL). These soft excitations lead to nonanalytic dependencies of observables, including the density of states, the spin susceptibility, and the specific heat, on the temperature, magnetic field, and wave number, which first appear at second order in the interaction. We determine and discuss the nature of these nonanalyticities in a DFL and compare them with the corresponding effects in a LFL. Our results are based on very general arguments regarding the existence and nature of the soft modes, and corroborated by explicit perturbative calculations. We also discuss their consequences for magnetic quantum phase transitions in Dirac metals.
The synergistic formation of zero (exponentially small) resistance states (ESRS) in high mobility two-dimensional electron systems (2DES) in a static magnetic field B and exposed to strong microwave (MW) radiation exhibits hysteresis and an anomalous logarithmic dependence on MW power. These synergistically organized states appear to be associated with a new kind of energy gap \Delta. Here I show that a microscopic quantum model that involves the Prime Number Theorem explains the MW power dependence of the energy gap \Delta. The explanation involves remarkable convergence with the most abstract ideas of modern mathematics.
The effect of magnetic bond disorder in otherwise antiferro nematic ordered system is investigated. We introduced triangular-shaped ferromagnetic bond disorder in the S=1 bilinear-biquadratic model on a triangular lattice. It is shown that the coupling between the impurity magnetic moment and nonmagnetic excitation in the bulk yields single-moment anisotropy and long-range anisotropic interaction between impurity magnetic moments. This interaction can induce unconventional spin-freezing phenomena observed in triangular magnet, NiGa2S4.
Using density-functional theory with the hybrid functional B3LYP, we investigate the electronic properties of polymers with diketo-pyrrolo-pyrrole (DPP) unit. We note that some of the polymers studied have LUCO energy similar to the C70-PCBM, or even lower, making them promising candidates for electron transport in organic photovoltaic devices. The homopolymer of DPP is predicted to have a band gap around 1.2 eV and shows a good dispersion of the conduction band.
We present twelve years of monitoring of the gravitational lens Q0142-100 from the Teide Observatory. The data, taken from 1999 to 2010, comprise 105 observing nights with the IAC80 telescope. The application of the delta2-method to the dataset leads to a value of the time delay between both components of the system of 72+/-22 days (68 per cent confidence level), consistent within the uncertainties with the latest previous results. With this value in mind a possible microlensing event is detected in Q0142-100.
We study an extension to the uniqueness conjecture for Markov numbers. For any three positive integers $m\geq a$ and $m\geq b$ satisfying $a^2+b^2+m^2=3abm$, this conjecture states that the triple $(a,m,b)$ is uniquely determined by the Markov number $m$. The theory of Markov numbers may be described by combinatorics of the sequences $(1,1)$ and $(2,2)$. There is an extension to the theory based on arbitrary sequences. We define extended uniqueness conjectures for any sequences $\mu$ and $\nu$. We show that for certain integers $a>1$ and $b>2$ the extended uniqueness conjecture for the sequences $\mu=(a,a)$ and $\nu=(b,b)$ fails.
One possible channel for black hole formation is the collapse of a rigidly rotating massive neutron star as it loses its angular momentum or gains excessive mass through accretion. It was proposed that part of the neutron star may form a debris disk around the black hole. Such short-lived massive disks could be the sources of powerful jets emitting cosmological gamma-ray bursts. Whether the collapse creates a disk depends on the equation of state of the neutron star. We survey a wide range of equations of states allowed by observations and find that disk formation is unfeasible. We conclude that this channel of black hole formation is incapable of producing powerful jets, and discuss implications for models of gamma-ray bursts.