6,551 research outputs found
Real-time moving object segmentation in H.264 compressed domain based on approximate reasoning
AbstractThis paper presents a real-time segmentation algorithm to obtain moving objects from the H.264 compressed domain. The proposed segmentation works with very little information and is based on two features of the H.264 compressed video: motion vectors associated to the macroblocks and decision modes. The algorithm uses fuzzy logic and allows to describe position, velocity and size of the detected regions in a comprehensive way, so the proposed approach works with low level information but manages highly comprehensive linguistic concepts. The performance of the algorithm is improved using dynamic design of fuzzy sets that avoids merge and split problems. Experimental results for several traffic scenes demonstrate the real-time performance and the encouraging results in diverse situations
Revealing the mid-infrared emission structure of IRAS 16594-4656 and IRAS 07027-7934
TIMMI2 diffraction-limited mid-infrared images of a multipolar
proto-planetary nebula IRAS 16594-4656 and a young [WC] elliptical planetary
nebula IRAS 07027-7934 are presented. Their dust shells are for the first time
resolved (only marginally in the case of IRAS 07027-7934) by applying the
Lucy-Richardson deconvolution algorithm to the data, taken under exceptionally
good seeing conditions (<0.5"). IRAS 16594-4656 exhibits a two-peaked
morphology at 8.6, 11.5 and 11.7 microns which is mainly attributed to emission
from PAHs. Our observations suggest that the central star is surrounded by a
toroidal structure observed edge-on with a radius of 0.4" (~640 AU at an
assumed distance of 1.6 kpc) with its polar axis at P.A.~80 degrees, coincident
with the orientation defined by only one of the bipolar outflows identified in
the HST optical images. We suggest that the material expelled from the central
source is currently being collimated in this direction and that the multiple
outflow formation has not been coeval. IRAS 07027-7934 shows a bright,
marginally extended emission (FWHM=0.3") in the mid-infrared with a slightly
elongated shape along the N-S direction, consistent with the morphology
detected by HST in the near-infrared. The mid-infrared emission is interpreted
as the result of the combined contribution of small, highly ionized PAHs and
relatively hot dust continuum. We propose that IRAS 07027-7934 may have
recently experienced a thermal pulse (likely at the end of the AGB) which has
produced a radical change in the chemistry of its central star.Comment: 35 pages, 8 figures (figures 1, 2, 4 and 6 are in low resolution)
accepted for publication in Ap
The Ring Imaging Cherenkov detector (RICH) of the AMS experiment
The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the
International Space Station (ISS) will be equipped with a proximity focusing
Ring Imaging Cherenkov (RICH) detector for measuring the electric charge and
velocity of the charged cosmic particles. A RICH prototype consisting of 96
photomultiplier units, including a piece of the conical reflector, was built
and its performance evaluated with ion beam data. Preliminary results of the
in-beam tests performed with ion fragments resulting from collisions of a 158
GeV/c/nuc primary beam of Indium ions (CERN SPS) on a Pb target are reported.
The collected data included tests to the final front-end electronics and to
different aerogel radiators. Cherenkov rings for a large range of charged
nuclei and with reflected photons were observed. The data analysis confirms the
design goals. Charge separation up to Fe and velocity resolution of the order
of 0.1% for singly charged particles are obtained.Comment: 29th International Conference on Cosmic Rays (Pune, India
The AMS-RICH velocity and charge reconstruction
The AMS detector, to be installed on the International Space Station,
includes a Ring Imaging Cerenkov detector with two different radiators, silica
aerogel (n=1.05) and sodium fluoride (n=1.334). This detector is designed to
provide very precise measurements of velocity and electric charge in a wide
range of cosmic nuclei energies and atomic numbers. The detector geometry, in
particular the presence of a reflector for acceptance purposes, leads to
complex Cerenkov patterns detected in a pixelized photomultiplier matrix. The
results of different reconstruction methods applied to test beam data as well
as to simulated samples are presented. To ensure nominal performances
throughout the flight, several detector parameters have to be carefully
monitored. The algorithms developed to fulfill these requirements are
presented. The velocity and charge measurements provided by the RICH detector
endow the AMS spectrometer with precise particle identification capabilities in
a wide energy range. The expected performances on light isotope separation are
discussed.Comment: Contribution to the ICRC07, Merida, Mexico (2007); Presenter: F.
Bara
The RICH detector of the AMS-02 experiment: status and physics prospects
The Alpha Magnetic Spectrometer (AMS), whose final version AMS-02 is to be
installed on the International Space Station (ISS) for at least 3 years, is a
detector designed to measure charged cosmic ray spectra with energies up to the
TeV region and with high energy photon detection capability up to a few hundred
GeV. It is equipped with several subsystems, one of which is a proximity
focusing RICH detector with a dual radiator (aerogel+NaF) that provides
reliable measurements for particle velocity and charge. The assembly and
testing of the AMS RICH is currently being finished and the full AMS detector
is expected to be ready by the end of 2008. The RICH detector of AMS-02 is
presented. Physics prospects are briefly discussed.Comment: 5 pages. Contribution to the 10th ICATPP Conference on Astroparticle,
Particle, Space Physics, Detectors and Medical Physics Applications (Como
2007). Presenter: Rui Pereir
POT1 and Damage Response Malfunction Trigger Acquisition of Somatic Activating Mutations in the VEGF Pathway in Cardiac Angiosarcomas
Background: Mutations in the POT1 gene explain abnormally long telomeres and multiple tumors including cardiac angiosarcomas (CAS). However, the link between long telomeres and tumorigenesis is poorly understood. Methods and Results: Here, we have studied the somatic landscape of 3 different angiosarcoma patients with mutations in the POT1 gene to further investigate this tumorigenesis process. In addition, the genetic landscape of 7 CAS patients without mutations in the POT1 gene has been studied. Patients with CAS and nonfunctional POT1 did not repress ATR (ataxia telangiectasia RAD3-related)-dependent DNA damage signaling and showed a constitutive increase of cell cycle arrest and somatic activating mutations in the VEGF (vascular endothelial growth factor)/angiogenesis pathway (KDR gene). The same observation was made in POT1 mutation carriers with tumors different from CAS and also in CAS patients without mutations in the POT1 gene but with mutations in other genes involved in DNA damage signaling. Conclusions: Inhibition of POT1 function and damage-response malfunction activated DNA damage signaling and increased cell cycle arrest as well as interfered with apoptosis, which would permit acquisition of somatic mutations in the VEGF/angiogenesis pathway that drives tumor formation. Therapies based on the inhibition of damage signaling in asymptomatic carriers may diminish defects on cell cycle arrest and thus prevent the apoptosis deregulation that leads to the acquisition of driver mutations
Advances on the automatic estimation of the P-wave onset time.
This work describes the automatic picking of the P-phase arrivals of the 3*10^6 seismic registers originated during the TOMO-ETNA experiment. Air-gun shots produced by the vessel âSarmiento de Gamboaâ and contemporary passive seismicity occurring in the island are recorded by a dense network of stations deployed for the experiment. In such scenario, automatic processing is needed given: (i) the enormous amount of data,
(ii) the low signal-to-noise ratio of many of the available registers and, (iii) the accuracy needed for the velocity tomography resulting from the experiment. A preliminary processing is performed with the records obtained from all stations. Raw data formats from the different types of stations are unified, eliminating defective records and reducing noise through filtering in the band of interest for the phase picking. The advanced multiband picking algorithm (AMPA) is then used to process the big database obtained and determine the travel times of the seismic phases. The approach of AMPA, based on frequency multiband denoising
and enhancement of expected arrivals through optimum detectors, is detailed together with its calibration and quality assessment procedure. Examples of its usage for active and passive seismic events are presented.PublishedS04342V. Dinamiche di unrest e scenari pre-eruttiviJCR Journalope
Atmospheric Muon Flux at Sea Level, Underground, and Underwater
The vertical sea-level muon spectrum at energies above 1 GeV and the
underground/underwater muon intensities at depths up to 18 km w.e. are
calculated. The results are particularly collated with a great body of the
ground-level, underground, and underwater muon data. In the hadron-cascade
calculations, the growth with energy of inelastic cross sections and pion,
kaon, and nucleon generation in pion-nucleus collisions are taken into account.
For evaluating the prompt muon contribution to the muon flux, we apply two
phenomenological approaches to the charm production problem: the recombination
quark-parton model and the quark-gluon string model. To solve the muon
transport equation at large depths of homogeneous medium, a semi-analytical
method is used. The simple fitting formulas describing our numerical results
are given. Our analysis shows that, at depths up to 6-7 km w. e., essentially
all underground data on the muon intensity correlate with each other and with
predicted depth-intensity relation for conventional muons to within 10%.
However, the high-energy sea-level data as well as the data at large depths are
contradictory and cannot be quantitatively decribed by a single nuclear-cascade
model.Comment: 47 pages, REVTeX, 15 EPS figures included; recent experimental data
and references added, typos correcte
Search for Branons at LEP
We search, in the context of extra-dimension scenarios, for the possible
existence of brane fluctuations, called branons. Events with a single photon or
a single Z-boson and missing energy and momentum collected with the L3 detector
in e^+ e^- collisions at centre-of-mass energies sqrt{s}=189-209$ GeV are
analysed. No excess over the Standard Model expectations is found and a lower
limit at 95% confidence level of 103 GeV is derived for the mass of branons,
for a scenario with small brane tensions. Alternatively, under the assumption
of a light branon, brane tensions below 180 GeV are excluded
Formation of the in Two-Photon Collisions at LEP
The two-photon width of the meson has been
measured with the L3 detector at LEP. The is studied in the decay
modes , KK, KK,
KK, , , and
using an integrated luminosity of 140 pb at GeV and
of 52 pb at GeV. The result is
(BR) keV. The dependence of the cross section is studied for
GeV. It is found to be better described by a Vector Meson
Dominance model form factor with a J-pole than with a -pole. In addition,
a signal of events is observed at the mass. Upper limits
for the two-photon widths of the , , and are also
given
- âŠ