991 research outputs found

    New species of Entomobryini from Russia and Armenia (Collembola, Entomobryomorpha)

    Get PDF
    This paper is part of the results of a systematic study of the specimens of Entomobrya and related genera from various European museums and other material obtained from private collections. Various new species from Russia and Armenia were identified: Entomobrya karasukensis n. sp., Entomobrya tuvinica n. sp., Entomobrya pseudolanuginosa n. sp., Entomobrya stebaevae n. sp., Entomobrya kuznetsovae n. sp., Entomobrya brinevi n. sp., Entomobrya primorica n. sp., Entomobrya kabardinica n. sp., Entomobrya taigicola n. sp., Entomobryoides sotoadamesi n. sp. and Prodrepanura altaica n. sp. from Russia, and Entomobrya armeniensis n. sp. from Armenia. For the identification and description of these species we used the set of characters proposed by Jordana and Baquero (2005)

    Can accretion properties distinguish between a naked singularity, wormhole and black hole?

    Full text link
    We first advance a mathematical novelty that the three geometrically and topologically distinct objects mentioned in the title can be exactly obtained from the Jordan frame vacuum Brans I solution by a combination of coordinate transformations, trigonometric identities and complex Wick rotation. Next, we study their respective accretion properties using the Page-Thorne model which studies accretion properties exclusively for rrmsr\geq r_{\text{ms}} (the minimally stable radius of particle orbits), while the radii of singularity/ throat/ horizon r<rmsr<r_{\text{ms}}. Also, its Page-Thorne efficiency ϵ\epsilon is found to increase with decreasing rmsr_{\text{ms}} and also yields ϵ=0.0572\epsilon=0.0572 for Schwarzschild black hole (SBH). But in the singular limit rrsr\rightarrow r_{s} (radius of singularity), we have ϵ1\epsilon\rightarrow 1 giving rise to 100%100 \% efficiency in agreement with the efficiency of the naked singularity constructed in [10]. We show that the differential accretion luminosity dLdlnr\frac{d\mathcal{L}_{\infty}}{d\ln{r}} of Buchdahl naked singularity (BNS) is always substantially larger than that of SBH, while Eddington luminosity at infinity LEddL_{\text{Edd}}^{\infty} for BNS could be arbitrarily large at rrsr\rightarrow r_{s} due to the scalar field ϕ\phi that is defined in (rs,)(r_{s}, \infty). It is concluded that BNS accretion profiles can still be higher than those of regular objects in the universe.Comment: 17 pages, 12 figure

    Photosensitive bismuth ions in lead tungstate

    Full text link
    Electron paramagnetic resonance (EPR) signals of Bi2+ ions have been detected in the EPR spectrum of manganese-, bismuth-, and tin-doped PbWO4 single-crystals irradiated by xenon and mercury lamps at 100 K. The parameters of the Zeeman, hyperfine, and superhyperfine interactions and the localization of Bi2+ ions have been determined. © 2013 Pleiades Publishing, Ltd

    Paramagnetic defects in manganese-doped lead tungstate

    Full text link
    In manganese-doped PbWO4 crystals, low-intensity signals of triclinic clusters Mn4+-VO and Fe3+-VPb have been revealed in addition to signals of Mn2+ tetragonal centers. The Mn4+-VO cluster is formed by a Mn4+ ion in the W6+ position, which is associated with a vacancy of the nearest neighbor O2-ion, and the Fe3+-VPb cluster consists of a Fe3+ ion substituting for Pb2+ with a local compensation of by a lead vacancy. It has been shown that, in PbWO4: Mn, there is also a small amount of Mn4+ tetragonal centers located in the Pb2+ position with a nonlocal compensation of an excess charge. © 2013 Pleiades Publishing, Ltd

    Quantum Field Theory in fractal space-time with negative Hausdorff-Colombeau dimensions.The solution cosmological constant problem

    Full text link
    We introduce Hausdorff-Colombeau measure in respect with negative fractal dimensions. Axiomatic quantum field theory in spacetime with negative fractal dimensions is proposed.Spacetime is modelled as a multifractal subset of R4R^{4} with positive and negative fractal dimensions.The cosmological constant problem arises because the magnitude of vacuum energy density predicted by quantum field theory is about 120 orders of magnitude larger than the value implied by cosmological observations of accelerating cosmic expansion. We pointed out that the fractal nature of the quantum space-time with negative Hausdorff-Colombeau dimensions can resolve this tension. The canonical Quantum Field Theory is widely believed to break down at some fundamental high-energy cutoff EE and therefore the quantum fluctuations in the vacuum can be treated classically seriously only up to this high-energy cutoff. In this paper we argue that Quantum Field Theory in fractal space-time with negative Hausdorff-Colombeau dimensions gives high-energy cutoff on natural way. In order to obtain disered physical result we apply the canonical Pauli-Villars regularization up to EE. It means that there exist the ghost-driven acceleration of the univers hidden in cosmological constant.Comment: 206 pages,3 figures. arXiv admin note: substantial text overlap with arXiv:0901.2208, arXiv:astro-ph/9708045, arXiv:1805.12293, arXiv:hep-th/0012253, arXiv:hep-th/9502025, arXiv:0912.4757, arXiv:0901.3775 by other author

    Improving Sequential Determinantal Point Processes for Supervised Video Summarization

    Full text link
    It is now much easier than ever before to produce videos. While the ubiquitous video data is a great source for information discovery and extraction, the computational challenges are unparalleled. Automatically summarizing the videos has become a substantial need for browsing, searching, and indexing visual content. This paper is in the vein of supervised video summarization using sequential determinantal point process (SeqDPP), which models diversity by a probabilistic distribution. We improve this model in two folds. In terms of learning, we propose a large-margin algorithm to address the exposure bias problem in SeqDPP. In terms of modeling, we design a new probabilistic distribution such that, when it is integrated into SeqDPP, the resulting model accepts user input about the expected length of the summary. Moreover, we also significantly extend a popular video summarization dataset by 1) more egocentric videos, 2) dense user annotations, and 3) a refined evaluation scheme. We conduct extensive experiments on this dataset (about 60 hours of videos in total) and compare our approach to several competitive baselines

    Can massless wormholes mimic a Schwarzschild black hole in the strong field lensing?

    Full text link
    Recent trend of research indicates that not only massive but also massless (asymptotic Newtonian mass zero) wormholes can reproduce post-merger initial ring-down gravitational waves characteristic of black hole horizon. In the massless case, it is the non-zero charge of other fields, equivalent to what we call here the "Wheelerian mass", that is responsible for mimicking ring-down quasi-normal modes. In this paper, we enquire whether the same Wheelerian mass can reproduce black hole observables also in an altogether different experiment, viz., the strong field lensing. We examine two classes of massless wormholes, one in the Einstein-Maxwell-Dilaton (EMD) theory and the other in the Einstein-Minimally-coupled-Scalar field (EMS) theory. The observables such as the radius of the shadow, image separation and magnification of the corresponding Wheelerian masses are compared with those of a black hole (idealized SgrA* chosen for illustration) assuming that the three types of lenses share the same minimum impact parameter and distance from the observer. It turns out that, while the massless EMS\ wormholes can closely mimic the black hole in terms of strong field lensing observables, the EMD wormholes show considerable differences due to the presence of dilatonic charge. The conclusion is that masslessless alone is enough to closely mimic Schwarzschild black hole strong lensing observables in the EMS theory but not in the other, where extra parameters also influence those observables. The motion of timelike particles is briefly discussed for completeness.Comment: 13 pages, 2 figure
    corecore