586 research outputs found
Automatic method for detection of characteristic areas in thermal face images
The use of thermal images of a selected area of the head in screening systems,
which perform fast and accurate analysis of the temperature distribution of individual areas,
requires the use of profiled image analysis methods. There exist methods for automated face
analysis which are used at airports or train stations and are designed to detect people with
fever. However, they do not enable automatic separation of specific areas of the face. This
paper presents an algorithm for image analysis which enables localization of characteristic
areas of the face in thermograms. The algorithm is resistant to subjects’ variability and also to
changes in the position and orientation of the head. In addition, an attempt was made to
eliminate the impact of background and interference caused by hair and hairline. The algorithm
automatically adjusts its operation parameters to suit the prevailing room conditions.
Compared to previous studies (Marzec et al., J Med Inform Tech 16:151–159, 2010), the set
of thermal images was expanded by 34 images. As a result, the research material was a total of
125 patients’ thermograms performed in the Department of Pediatrics and Child and
Adolescent Neurology in Katowice, Poland. The images were taken interchangeably with
several thermal cameras: AGEMA 590 PAL (sensitivity of 0.1 °C), ThermaCam S65
(sensitivity of 0.08 °C), A310 (sensitivity of 0.05 °C), T335 (sensitivity of 0.05 °C) with a
320Ă—240 pixel optical resolution of detectors, maintaining the principles related to taking
thermal images for medical thermography. In comparison to (Marzec et al., J Med Inform Tech
16:151–159, 2010), the approach presented there has been extended and modified. Based on
the comparison with other methods presented in the literature, it was demonstrated that this
method is more complex as it enables to determine the approximate areas of selected parts of the face including anthropometry. As a result of this comparison, better results were obtained
in terms of localization accuracy of the center of the eye sockets and nostrils, giving an
accuracy of 87 % for the eyes and 93 % for the nostrils
Spin-dependent resonant tunneling in ZnSe/ZnMnSe heterostructures
Using the transfer matrix method and the effective-mass approximation, the
effect of resonant states on spin transport is studied in
ZnSe/ZnMnSe/ZnSe/ZnMnSe/ZnSe structures under the influence of both electric
and magnetic fields. The numerical results show that the ZnMnSe layers, which
act as spin filters, polarize the electric currents. Variation of thickness of
the central ZnSe layer shifts the resonant levels and exhibits an oscillatory
behavior in spin current densities. It is also shown that the spin polarization
of the tunneling current in geometrical asymmetry of the heterostructure where
two ZnMnSe layers have different Mn concentrations, depends strongly on the
thickness and the applied bias.Comment: 13 pages, 6 figure
Strongly damped nuclear collisions: zero or first sound ?
The relaxation of the collective quadrupole motion in the initial stage of a
central heavy ion collision at beam energies AMeV is studied
within a microscopic kinetic transport model. The damping rate is shown to be a
non-monotonic function of E_{lab} for a given pair of colliding nuclei. This
fact is interpreted as a manifestation of the zero-to-first sound transition in
a finite nuclear system.Comment: 15 pages, 4 figure
Interlayer Exchange Coupling Mediated by Valence Band Electrons
The interlayer exchange coupling mediated by valence band electrons in
all-semiconductor IV-VI magnetic/nonmagnetic superlattices is studied
theoretically. A 3D tight-binding model, accounting for the band and magnetic
structure of the constituent superlattice components is used to calculate the
spin-dependent part of the total electronic energy. The antiferromagnetic
coupling between ferromagnetic layers in EuS/PbS superlattices is obtained, in
agreement with the experimental evidences. The results obtained for the
coupling between antiferromagnetic layers in EuTe/PbTe superlattices are also
presented.Comment: 8 pages, 6 figures, to be submitted to Phys.Rev.
Correlations between isospin dynamics and Intermediate Mass Fragments emission time scales: a probe for the symmetry energy in asymmetric nuclear matter
We show new data from the Ni+Sn and Ni+Sn
reactions studied in direct kinematics with the CHIMERA detector at INFN-LNS
and compared with the reverse kinematics reactions at the same incident beam
energy (35 A MeV). Analyzing the data with the method of relative velocity
correlations, fragments coming from statistical decay of an excited
projectile-like (PLF) or target-like (TLF) fragments are discriminated from the
ones coming from dynamical emission in the early stages of the reaction. By
comparing data of the reverse kinematics experiment with a stochastic mean
field (SMF) + GEMINI calculations our results show that observables from neck
fragmentation mechanism add valuable constraints on the density dependence of
symmetry energy. An indication is found for a moderately stiff symmetry energy
potential term of EOS.Comment: Talk given by E. De Filippo at the 11th International Conference on
Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1,
2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference
Series (JPCS
Projected Quasi-particle Perturbation theory
The BCS and/or HFB theories are extended by treating the effect of four
quasi-particle states perturbatively. The approach is tested on the pairing
hamiltonian, showing that it combines the advantage of standard perturbation
theory valid at low pairing strength and of non-perturbative approaches
breaking particle number valid at higher pairing strength. Including the
restoration of particle number, further improves the description of pairing
correlation. In the presented test, the agreement between the exact solution
and the combined perturbative + projection is almost perfect. The proposed
method scales friendly when the number of particles increases and provides a
simple alternative to other more complicated approaches
Upper limit on the photon fraction in highest-energy cosmic rays from AGASA data
A new method to derive an upper limit on photon primaries from small data
sets of air showers is developed which accounts for shower properties varying
with the primary energy and arrival direction. Applying this method to the
highest-energy showers recorded by the AGASA experiment, an upper limit on the
photon fraction of 51% (67%) at a confidence level of 90% (95%) for primary
energies above 1.25 * 10^20 eV is set. This new limit on the photon fraction
above the GZK cutoff energy constrains the Z-burst model of the origin of
highest-energy cosmic rays.Comment: 4 pages, 3 figures. Analysis extended to account for primary energy
resolution; conclusions unchanged. Accepted by Phys. Rev. Let
Ultrastructural visualization of 3D chromatin folding using volume electron microscopy and DNA in situ hybridization.
The human genome is extensively folded into 3-dimensional organization. However, the detailed 3D chromatin folding structures have not been fully visualized due to the lack of robust and ultra-resolution imaging capability. Here, we report the development of an electron microscopy method that combines serial block-face scanning electron microscopy with in situ hybridization (3D-EMISH) to visualize 3D chromatin folding at targeted genomic regions with ultra-resolution (5 × 5 × 30 nm in xyz dimensions) that is superior to the current super-resolution by fluorescence light microscopy. We apply 3D-EMISH to human lymphoblastoid cells at a 1.7 Mb segment of the genome and visualize a large number of distinctive 3D chromatin folding structures in ultra-resolution. We further quantitatively characterize the reconstituted chromatin folding structures by identifying sub-domains, and uncover a high level heterogeneity of chromatin folding ultrastructures in individual nuclei, suggestive of extensive dynamic fluidity in 3D chromatin states
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