991 research outputs found
New species of Entomobryini from Russia and Armenia (Collembola, Entomobryomorpha)
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?
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 (the
minimally stable radius of particle orbits), while the radii of singularity/
throat/ horizon . Also, its Page-Thorne efficiency
is found to increase with decreasing and also yields
for Schwarzschild black hole (SBH). But in the singular limit
(radius of singularity), we have
giving rise to efficiency in agreement with the efficiency of the
naked singularity constructed in [10]. We show that the differential accretion
luminosity of Buchdahl naked
singularity (BNS) is always substantially larger than that of SBH, while
Eddington luminosity at infinity for BNS could be
arbitrarily large at due to the scalar field that
is defined in . 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
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
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
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
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 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 . 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
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?
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
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