ShantanuT01/DACTYL-Pretraining huggingface dataset:
Observational evidence suggests that our universe is currently evolving towards an asymptotically de Sitter future. Unfortunately and in spite of much recent attention, various quantum, holographic and cosmological aspects of de Sitter space remain quite enigmatic. With such intrigue in mind, this paper considers the ``construction'' of a toy model that describes an asymptotically de Sitter universe. More specifically, we add fluid-like matter to an otherwise purely de Sitter spacetime, formulate the relevant solutions and then discuss the cosmological and holographic implications. If the objective is to construct an asymptotically de Sitter universe that is free of singularities and has a straightforward holographic interpretation, then the results of this analysis are decidedly negative. Nonetheless, this toy model nicely illustrates the pitfalls that might be encountered in a more realistic type of construction.
In 1989 Cabrera and Tate reported an anomalous excess of mass of the Cooper pairs in rotating thin Niobium rings. So far, this experimental result never received a proper theoretical explanation in the context of superconductor's physics. In the present work we argue that what Cabrera and Tate interpreted as an anomalous excess of mass can also be associated with a deviation from the classical gravitomagnetic Larmor theorem due to the presence of dark energy in the superconductor, as well as with the discrete structure of the area of the superconducting Niobium ring as predicted by Loop Quantum Gravity. From Cabrera and Tate measurements we deduce that the quantization of spacetime in superconducting circular rings occurs at the Planck-Einstein scale $l_{PE} = (\hbar G/c^3 \Lambda)^{1/4}\sim 3.77\times 10 ^{-5} m$, instead of the Planck scale $l_{P} =(\hbar G / c^3)^{1/2}=1.61 \times 10 ^{-35} m$, with an Immirzi parameter which depends on the specific critical temperature of the superconducting material and on the area of the ring. The stephan-Boltzmann law for quantized areas delimited by superconducting rings is predicted, and an experimental concept based on the electromagnetic black-body radiation emitted by this surfaces, is proposed to test loop quantum gravity and electromagnetic dark energy in superconductors.
We present new spectroscopic observations in a field containing the highest redshift cluster of the ESO Distant Cluster Survey (EDisCS). We measure galaxy redshifts and determine the velocity dispersions of the galaxy structures located in this field. Together with the main cluster Cl1103.7$-$1245 (z=0.9580; sigma_{clus} = 522 +/- 111 km/s) we find a secondary structure at z=0.9830, Cl1103.7-1245c. We then characterize the galaxy properties in both systems, and find that they contain very different galaxy populations. The cluster Cl1103.7-1245 hosts a mixture of passive elliptical galaxies and star-forming spirals and irregulars. In the secondary structure Cl1103.7-1245c all galaxies are lower-mass star-forming irregulars and peculiars. In addition, we compare the galaxy populations in the Cl1103.7-1245 z=0.9580 cluster with those in lower redshift EDisCS clusters with similar velocity dispersions. We find that the properties of the galaxies in Cl1103.7-1245 follow the evolutionary trends found at lower redshifts: the number of cluster members increases with time in line with the expected growth in cluster mass, and the fraction of passive early-type galaxies increases with time while star-forming late types become less dominant. Finally, we find that the mean stellar masses are similar in all clusters, suggesting that massive cluster galaxies were already present at z~1.
Object pose estimation is crucial for robotic applications and augmented reality. Beyond instance level 6D object pose estimation methods, estimating category-level pose and shape has become a promising trend. As such, a new research field needs to be supported by well-designed datasets. To provide a benchmark with high-quality ground truth annotations to the community, we introduce a multimodal dataset for category-level object pose estimation with photometrically challenging objects termed PhoCaL. PhoCaL comprises 60 high quality 3D models of household objects over 8 categories including highly reflective, transparent and symmetric objects. We developed a novel robot-supported multi-modal (RGB, depth, polarisation) data acquisition and annotation process. It ensures sub-millimeter accuracy of the pose for opaque textured, shiny and transparent objects, no motion blur and perfect camera synchronisation. To set a benchmark for our dataset, state-of-the-art RGB-D and monocular RGB methods are evaluated on the challenging scenes of PhoCaL.
The reported temperature variations of CeB6 s magnetic entropy are inconsistent with the fourfold degeneracy of the crystal field ground state. This old question is here addressed through new specific heat measurements and an improved description, in the cage context, of both the phonons and crystal field contributions to the specific heat. The antiferromagnetic transition is characterized as first-order and its latent heat determined. From the phonons dispersion for a cage compound, the lattice specific heat contribution is derived from the LaB6 data. Once corrected for the first-order transition and lattice contributions, the magnetic entropy displays the characteristic plateau of the quadruplet crystal field ground state, but at temperatures in excess of 30 K. Below 30 K, as the ordering temperature is approached, the magnetic entropy is substantially reduced. This anomalous temperature dependence is consistent with a crystal field ground state split by the rare-earth movement, a phenomenon specific to rare-earth cage compounds.
In this paper we have applied Bohmian quantum theory to the linear field approximation of gravity and present a self--consistent quantum gravity theory in the linear field approximation. The theory is then applied to some specific problems, the Newtonian limit, and the static spherically symmetric solution. Some observable effects of the theory are investigated.
Following up on the recent work of Cachazo, He and Yuan \cite{arXiv:1503.04816 [hep-th]}, we derive the double soft graviton theorem in perturbative gravity. We show that the double soft theorem derived using CHY formula precisely matches with the perturbative computation involving Feynman diagrams. In particular, we find how certain delicate limits of Feynman diagrams play an important role in obtaining this equivalence.
We perform a general 1-loop analysis by adding extra matter to the SM content, as well as by allowing a non-standard U(1)Y normalization in order to achieve unification. We find numerous solutions with U(1)Y only charged extra matter and unification scale of the order of MU=10^{16} GeV, or with SU(2) charged extra matter with lower MU. We next identify the SM extra matter as originating from the breaking of SO(10) either through the Pati-Salam group SU(4)xSU(2)LxSU(2)R or the flipped SU(5). In both cases, unification can be achieved with a rather minimal extra content. Contrary to the one-step SU(5) unification, in the two-step SO(10) unification we are discussing, coulored extra matter is not necessary. Finally, we discuss a split-supersymmetry like case, where extra matter is added to the split supersymmetric spectrum in order to attain 1-loop unification.
We study several examples of surfaces with $p_g = q = 2$ and maximal Albanese dimension that are endowed with an irrational fibration.
Betelgeuse, the bright, cool red supergiant in Orion, is moving supersonically relative to the local interstellar medium. The star emits a powerful stellar wind which collides with this medium, forming a cometary structure, a bow shock, pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse's bow shock. The models include realistic low temperature cooling and cover a range of plausible interstellar medium densities and stellar velocities between 0.3 - 1.9 cm-3 and 28 - 73 km/s. We show that the flow dynamics and morphology of the bow shock differ substantially due to the preferential growth of Rayleigh-Taylor or Kelvin-Helmholtz instabilities in the models. The former dominate the models with slow stellar velocities resulting in a clumpy bow shock sub-structure, whereas the latter produce a smoother, more layered sub-structure in the fast models. If the mass in the bow shock shell is low, as seems to be implied by the AKARI luminosities (~0.003 Msun), then Betelgeuse's bow shock is very young and is unlikely to have reached a steady state. The circular nature of the bow shock shell is consistent with this conclusion. Thus, our results suggest that Betelgeuse entered the red supergiant phase only recently.
Recent advances in deep learning methods have come to define the state-of-the-art for many medical imaging applications, surpassing even human judgment in several tasks. Those models, however, when trained to reduce the empirical risk on a single domain, fail to generalize when applied to other domains, a very common scenario in medical imaging due to the variability of images and anatomical structures, even across the same imaging modality. In this work, we extend the method of unsupervised domain adaptation using self-ensembling for the semantic segmentation task and explore multiple facets of the method on a small and realistic publicly-available magnetic resonance (MRI) dataset. Through an extensive evaluation, we show that self-ensembling can indeed improve the generalization of the models even when using a small amount of unlabelled data.
A general overview of the understanding of our Galaxy is presented following the lines of its main structures: halo, disc, bulge/bar. This review is emphasising some "Time Domain Astronomy" contributions. On the one hand the distance and tangential motion of the stars are essential to this understanding and are obtained through multi-epoch surveys, on the other hand the chemistry of the stars, and their radial velocity are also key elements to map Galactic (sub-)structures and unravel their history and evolution. Contemporary surveys are revolutionising our view of the Milky Way and galaxies in general. Among these, the Gaia mission excels by its precision astrometry of 1.3 billion stars stretching through the Milky Way and beyond, providing the first 3D view of a major part of the Milky Way.
The quasineutral limit of compressible Navier-Stokes-Poisson system with heat conductivity and general (ill-prepared) initial data is rigorously proved in this paper. It is proved that, as the Debye length tends to zero, the solution of the compressible Navier-Stokes-Poisson system converges strongly to the strong solution of the incompressible Navier-Stokes equations plus a term of fast singular oscillating gradient vector fields. Moreover, if the Debye length, the viscosity coefficients and the heat conductivity coefficient independently go to zero, we obtain the incompressible Euler equations. In both cases the convergence rates are obtained.
We studied the drift of electron spins under an applied DC electric field in single layer graphene spin valves in a field effect transport geometry at room temperature. In the metallic conduction regime ($n \simeq 3.5 \times 10^{16}$ m$^{-2}$), for DC fields of about $\pm$70 kV/m applied between the spin injector and spin detector, the spin valve signals are increased/decreased, depending on the direction of the DC field and the carrier type, by as much as $\pm$50%. Sign reversal of the drift effect is observed when switching from hole to electron conduction. In the vicinity of the Dirac neutrality point the drift effect is strongly suppressed. The experiments are in quantitative agreement with a drift-diffusion model of spin transport.
Recently, video captioning has been attracting an increasing amount of interest, due to its potential for improving accessibility and information retrieval. While existing methods rely on different kinds of visual features and model structures, they do not fully exploit relevant semantic information. We present an extensible approach to jointly leverage several sorts of visual features and semantic attributes. Our novel architecture builds on LSTMs for sentence generation, with several attention layers and two multimodal layers. The attention mechanism learns to automatically select the most salient visual features or semantic attributes, and the multimodal layer yields overall representations for the input and outputs of the sentence generation component. Experimental results on the challenging MSVD and MSR-VTT datasets show that our framework outperforms the state-of-the-art approaches, while ground truth based semantic attributes are able to further elevate the output quality to a near-human level.
We calculate open charm and charmonium production in $Au+Au$ reactions at $\sqrt{s}$ = 200 GeV within the hadron-string dynamics (HSD) transport approach employing open charm cross sections from $pN$ and $\pi N$ reactions that are fitted to results from PYTHIA and scaled in magnitude to the available experimental data. Charmonium dissociation with nucleons and formed mesons to open charm ($D+\bar{D}$ pairs) is included dynamically. The 'comover' dissociation cross sections are described by a simple phase-space model including a single free parameter, i.e. an interaction strength $M_0^2$, that is fitted to the $J/\Psi$ suppression data for $Pb+Pb$ collisions at SPS energies. As a novel feature we implement the backward channels for charmonium reproduction by $D \bar{D}$ channels employing detailed balance. From our dynamical calculations we find that the charmonium recreation is comparable to the dissociation by 'comoving' mesons. This leads to the final result that the total $J/\Psi$ suppression at $\sqrt{s}$ = 200 GeV as a function of centrality is slightly less than the suppression seen at SPS energies by the NA50 Collaboration, where the 'comover' dissociation is substantial and the backward channels play no role. Furthermore, even in case that all directly produced $J/\Psi$ mesons dissociate immediately (or are not formed as a mesonic state), a sizeable amount of charmonia is found asymptotically due to the $D+\bar{D} \to J/\Psi$ + meson channels in central collisions of $Au+Au$ at $\sqrt{s}$ = 200 GeV which, however, is lower than the $J/\Psi$ yield expected from binary scaling of $pp$ collisions.
We generalize the classic change-point problem to a "change-set" framework: a spatial Poisson process changes its intensity on an unobservable random set. Optimal detection of the set is defined by maximizing the expected value of a gain function. In the case that the unknown change-set is defined by a locally finite set of incomparable points, we present a sufficient condition for optimal detection of the set using multiparameter martingale techniques. Two examples are discussed.
Recently Oguiso showed the existence of K3 surfaces that admit a fixed point free automorphism of positive entropy. The K3 surfaces used by Oguiso have a particular rank two Picard lattice. We show, using results of Beauville, that these surfaces are therefore determinantal quartic surfaces. Long ago, Cayley constructed an automorphism of such determinantal surfaces. We show that Cayley's automorphism coincides with Oguiso's free automorphism. We also exhibit an explicit example of a determinantal quartic whose Picard lattice has exactly rank two and for which we thus have an explicit description of the automorphism.
We present the results of high spatial resolution HCO$^{+}$($1-0$) and HCN($1-0$) observations of N55 south region (N55-S) in the Large Magellanic Cloud (LMC), obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). N55-S is a relatively less extreme star-forming region of the LMC characterized by a low radiation field. We carried out a detailed analysis of the molecular emission to investigate the relation between dense molecular clumps and star formation in the quiescent environment of N55-S. We detect ten molecular clumps with significant HCO$^{+}(1-0)$ emission and eight with significant HCN($1-0$) emission, and estimate the molecular clump masses by virial and local thermodynamic equilibrium analysis. All identified young stellar objects (YSOs) in the N55-S are found to be near the HCO$^{+}$ and HCN emission peaks showing the association of these clumps with recent star formation activity. The molecular clumps that have associated YSOs show relatively larger linewidths and masses than those without YSOs. We compare the clump properties of the N55-S with those of other giant molecular clouds (GMCs) in the LMC and find that N55-S clumps possess similar size but relatively lower linewidth and larger HCN/HCO$^{+}$(1$-$0) flux ratio. These results can be attributed to the low radiation field in N55-S resulted by relatively low star formation activity compared to other active star-forming regions like 30Doradus-10 and N159. The dense gas fraction of N55-S is $\sim$ 0.025, lower compared to other GMCs of the LMC supporting the low star formation efficiency of this region.
We present a regularized maximum likelihood weak lensing reconstruction of the Deep Lens Survey F2 field (4 deg^2). High signal-to-noise ratio peaks in our lensing significance map appear to be associated with possible projected filamentary structures. The largest apparent structure extends for over a degree in the field and has contributions from known optical clusters at three redshifts (z ~ 0.3, 0.43, 0.5). Noise in weak lensing reconstructions is known to potentially cause "false positives"; we use Monte Carlo techniques to estimate the contamination in our sample, and find that 10-25% of the peaks are expected to be false detections. For significant lensing peaks we estimate the total signal-to-noise ratio of detection using a method that accounts for pixel-to-pixel correlations in our reconstruction. We also report the detection of a candidate relative underdensity in the F2 field with a total signal-to-noise ratio of ~ 5.5.
Background: In the last few decades quantum phase transitions have been of great interest in Nuclear Physics. In this context, two-fluid algebraic models are ideal systems to study how the concept of quantum phase transition evolves when moving into more complex systems, but the number of publications along this line has been scarce up to now.   Purpose: We intend to determine the phase diagram of a two-fluid Lipkin model, that resembles the nuclear proton-neutron interacting boson model Hamiltonian, using both numerical results and analytic tools, i.e., catastrophe theory, and to compare the mean-field results with exact diagonalizations for large systems. Method: The mean-field energy surface of a consistent-Q-like two-fluid Lipkin Hamiltonian is studied and compared with exact results coming from a direct diagonalization. The mean-field results are analyzed using the framework of catastrophe theory.   Results: The phase diagram of the model is obtained and the order of the different phase-transition lines and surfaces is determined using a catastrophe theory analysis.   Conclusions: There are two first order surfaces in the phase diagram, one separating the spherical and the deformed shapes, while the other separates two different deformed phases. A second order line, where the later surfaces merge, is found. This line finishes in a transition point with a divergence in the second order derivative of the energy that corresponds to a tricritical point in the language of the Ginzburg-Landau theory for phase transitions.
We have discovered strong gravitational lensing features in the core of the nearby cluster Abell 3827 by analyzing Gemini South GMOS images. The most prominent strong lensing feature is a highly-magnified, ring-shaped configuration of four images around the central cD galaxy. GMOS spectroscopic analysis puts this source at z~0.2. Located ~20" away from the central galaxy is a secondary tangential arc feature which has been identified as a background galaxy with z~0.4. We have modeled the gravitational potential of the cluster core, taking into account the mass from the cluster, the BCG and other galaxies. We derive a total mass of (2.7 +- 0.4) x 10^13 Msun within 37 h^-1 kpc. This mass is an order of magnitude larger than that derived from X-ray observations. The total mass derived from lensing data suggests that the BCG in this cluster is perhaps the most massive galaxy in the nearby Universe.
In this article I present a protocol for quantum cryptography which is secure against attacks on individual signals. It is based on the Bennett-Brassard protocol of 1984 (BB84). The security proof is complete as far as the use of single photons as signal states is concerned. Emphasis is given to the practicability of the resulting protocol. For each run of the quantum key distribution the security statement gives the probability of a successful key generation and the probability for an eavesdropper's knowledge, measured as change in Shannon entropy, to be below a specified maximal value.
We study the dependence of the dimensional character of the charge-density wave (CDW) in TiSe$_2$ by a controlled variation of the number of available charge carriers in the conduction band. A change of dimensionality is realised by H2O exposure and monitored by angle-resolved photoelectron spectroscopy. The CDW spanning vector changes from 2x2x1 towards 1x1x2 in a narrow population range, just before a complete suppression of the CDW. Our findings enable a new view on the excitonic origin of the CDW, the relation between CDW spanning vector and periodic lattice distortion, and suggest modifications in the picture of the recently discovered chirality of the CDW.
Within the instanton liquid model, we study the dependence of the gauge invariant two--point quark correlator on the path used to perform the color parallel transport between two points in the Euclidean space.
We present absolute physical and orbital parameters for three double-lined detached eclipsing binary systems from the All Sky Automated Survey (ASAS) catalogue with subgiant and giant components. These parameters were derived from archival V-band ASAS photometry and new radial velocities. The radial velocities were calculated from high quality optical spectra we obtained with the 8.2 m Subaru/HDS, ESO 3.6 m/HARPS, 1.9 m Radcliffe/GIRAFFE, CTIO 1.5 m/CHIRON, and 1.2 m Euler/CORALIE using the two-dimensional cross-correlation technique (TODCOR) and synthetic template spectra chosen for every system separately as references.   The physical and orbital parameters of the systems were derived with the PHOEBE and JKTEBOP codes. We checked the evolutionary status of the systems with several sets of isochrones and determined distances for each system. The derived uncertainties for individual masses of ASAS J010538-8003.7, ASAS J182510-2435.5, and V1980 Sgr components vary from 0.7% to 3.6% while the radii are in the range 1% to 24%. For all of the investigated systems such a detailed orbital and physical analysis is presented for the first time.
We present the results of our ongoing investigation into the properties of hot stars and young stellar populations using the Swift/UVOT telescope. We present UVOT photometry of open and globular clusters and show that UVOT is capable of characterizing a variety of rare hot stars, including Post-Asymptotic Giant Branch and Extreme Horizontal Branch Stars. We also present very early reults of our survey of stellar populations in the Small Magellanic Cloud. We find that the SMC has experienced recent bouts of star formation but constraining the exact star formation history will depend on finding an effective model of the reddening within the SMC.