1,479 research outputs found
Towards Semantic Fast-Forward and Stabilized Egocentric Videos
The emergence of low-cost personal mobiles devices and wearable cameras and
the increasing storage capacity of video-sharing websites have pushed forward a
growing interest towards first-person videos. Since most of the recorded videos
compose long-running streams with unedited content, they are tedious and
unpleasant to watch. The fast-forward state-of-the-art methods are facing
challenges of balancing the smoothness of the video and the emphasis in the
relevant frames given a speed-up rate. In this work, we present a methodology
capable of summarizing and stabilizing egocentric videos by extracting the
semantic information from the frames. This paper also describes a dataset
collection with several semantically labeled videos and introduces a new
smoothness evaluation metric for egocentric videos that is used to test our
method.Comment: Accepted for publication and presented in the First International
Workshop on Egocentric Perception, Interaction and Computing at European
Conference on Computer Vision (EPIC@ECCV) 201
The String Coupling Accelerates the Expansion of the Universe
Generic cosmological models in non-critical string theory have a
time-dependent dilaton background at a late epoch. The cosmological
deceleration parameter Q_0 is given by the square of the string coupling,
g_s^2, up to a negative sign. Hence the expansion of the Universe must
accelerate eventually, and the observed value of Q_0 coresponds to g_s^2 ~ 0.6.
In this scenario, the string coupling is asymptotically free at large times,
but its present rate of change is imperceptibly small.Comment: 7 page
Effective Potential on Fuzzy Sphere
The effective potential of quantized scalar field on fuzzy sphere is
evaluated to the two-loop level. We see that one-loop potential behaves like
that in the commutative sphere and the Coleman-Weinberg mechanism of the
radiatively symmetry breaking could be also shown in the fuzzy sphere system.
In the two-loop level, we use the heavy-mass approximation and the
high-temperature approximation to perform the evaluations. The results show
that both of the planar and nonplanar Feynman diagrams have inclinations to
restore the symmetry breaking in the tree level. However, the contributions
from planar diagrams will dominate over those from nonplanar diagrams by a
factor N^2. Thus, at heavy-mass limit or high-temperature system the quantum
field on the fuzzy sphere will behave like those on the commutative sphere. We
also see that there is a drastic reduction of the degrees of freedom in the
nonplanar diagrams when the particle wavelength is smaller than the
noncommutativity scale.Comment: Latex 18 pages, some typos correcte
Central Venous Catheter Infection with Brevibacterium sp. in an Immunocompetent Woman: Case Report and Review of the Literature
Brevibacterium spp. were considered apathogenic until a few reports of infections in immunocompromised patients were published. Herein, we present a case of a catheter-related septicemia with Brevibacterium casei in an immunocompetent patient receiving continuous iloprost infusion for pulmonary arterial hypertension and review the clinical presentation of this mainly emerging opportunistic pathoge
Holographic dark energy model with non-minimal coupling
We find that holographic dark energy model with non-minimally coupled scalar
field gives rise to an accelerating universe by choosing Hubble scale as IR
cutoff. We show viable range of a non-minimal coupling parameter in the
framework of this model.Comment: 7 pages, no figure, corrected some typos, to be published in
Europhys. Let
A finite cutoff on the string worldsheet?
D-brane backgrounds are specified in closed string theories by holes with
appropriate mixed Dirichlet and Neumann boundary conditions on the string
worldsheet. As presently stated, the prescription defining D-brane backgrounds
is such that the Einstein equation is not equivalent to the condition for scale
invariance on the string worldsheet. A modified D-brane prescription is found,
that leads to the desired equivalence, while preserving all known D-brane lore.
A possible interpretation is that the worldsheet cutoff is finite. Possible
connections to recent work of Maldacena and Strominger, and Gopakumar and Vafa
are suggested.Comment: 7 pages, RevTex; v2: typos corrected, superstring calculation
included, discussion expanded - to be published in Phys.Rev.
Dirichlet boundary value problem for Chern-Simons modified gravity
Chern-Simons modified gravity comprises the Einstein-Hilbert action and a
higher-derivative interaction containing the Chern-Pontryagin density. We
derive the analog of the Gibbons-Hawking-York boundary term required to render
the Dirichlet boundary value problem well-defined. It turns out to be a
boundary Chern-Simons action for the extrinsic curvature. We address
applications to black hole thermodynamics.Comment: 4 pages, revtex4, v2: added Refs., made one statement stronger, added
footnote and added paragraph on single field inflatio
Mirage Cosmology on Unstable D3-Brane Universe
We study the geodesic motion of an unstable brane moving in a higher
dimensional bulk spacetime. The tachyon which is coupled to a U(1) gauge field
induces a non-trivial cosmological evolution. Interestingly enough, this system
exhibits a much smoother initial cosmological singularity in comparison with
former works.Comment: 6 pages. Talk at the RTN conference ``The Quest for Unification:
Theory Confronts Experiment", Corfu, Greece, Sept, 11-18, 200
Leptogenesis from Pseudo-Scalar Driven Inflation
We examine recent claims for a considerable amount of leptogenesis, in some
inflationary scenarios, through the gravitational anomaly in the lepton number
current. We find that when the short distances contributions are properly
included the amount of lepton number generated is actually much smaller.Comment: JHEP style, 11 pages. Corrected typ
Loop quantum gravity effects on inflation and the CMB
In loop quantum cosmology, the universe avoids a big bang singularity and
undergoes an early and short super-inflation phase. During super-inflation,
non-perturbative quantum corrections to the dynamics drive an inflaton field up
its potential hill, thus setting the initial conditions for standard inflation.
We show that this effect can raise the inflaton high enough to achieve
sufficient e-foldings in the standard inflation era. We analyze the
cosmological perturbations generated when slow-roll is violated after
super-inflation, and show that loop quantum effects can in principle leave an
indirect signature on the largest scales in the CMB, with some loss of power
and running of the spectral index.Comment: revtex4, 5 pages, 3 figures, significant improvements in explanation
of quantization and perturbation issues; version to appear Classical and
Quantum Gravit
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