2,894 research outputs found
Computer-Assisted Segmentation of Videocapsule Images Using Alpha-Divergence-Based Active Contour in the Framework of Intestinal Pathologies Detection
Visualization of the entire length of the gastrointestinal tract through natural orifices is a challenge for endoscopists. Videoendoscopy is currently the “gold standard” technique for diagnosis of different pathologies of the intestinal tract. Wireless Capsule Endoscopy (WCE) has been developed in the 1990's as an alternative to videoendoscopy to allow direct examination of the gastrointestinal tract without any need for sedation. Nevertheless, the systematic post-examination by the specialist of the 50,000 (for the small bowel) to 150,000 images (for the colon) of a complete acquisition using WCE remains time-consuming and challenging due to the poor quality of WCE images. In this article, a semiautomatic segmentation for analysis of WCE images is proposed. Based on active contour segmentation, the proposed method introduces alpha-divergences, a flexible statistical similarity measure that gives a real flexibility to different types of gastrointestinal pathologies. Results of segmentation using the proposed approach are shown on different types of real-case examinations, from (multi-) polyp(s) segmentation, to radiation enteritis delineation
Unconventional Metallic Magnetism in LaCrSb{3}
Neutron-diffraction measurements in LaCrSb{3} show a coexistence of
ferromagnetic and antiferromagnetic sublattices below Tc=126 K, with ordered
moments of 1.65(4) and 0.49(4) Bohr magnetons per formula unit, respectively
(T=10 K), and a spin reorientation transition at ~95 K. No clear peak or step
was observed in the specific heat at Tc. Coexisting localized and itinerant
spins are suggested.Comment: PRL, in pres
Coupling of phonons with orbital dynamics and magnetism in CuSb2O6
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOStrongly interacting phonons and orbital excitations are observed in the same energy range for CuSb2O6, unlocking a so-far unexplored type of electron-phonon interaction. An orbital wave at similar to 550 cm(-1) softens on warming and strongly interferes with a phonon at similar to 500 cm(-1), giving rise to a merged excitation of mixed character. An electronic continuum grows on warming to the orbital ordering temperature T-oo = 400 K, generating an important phonon decay channel. This direct and simultaneous observation of orbital and vibrational excitations reveals details of their combined dynamics. In addition, phonon frequency anomalies due to magnetic correlations are observed below similar to 150 K, much above the three-dimensional magnetic ordering temperature T-N(3D) = 8.5 K, confirming one-dimensional magnetic correlations along Cu-O-O-Cu linear chains in the paramagnetic state.971715FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2012/04870-7Sem informaçãoSem informaçãoAgências de fomento estrangeiras apoiaram essa pesquisa, mais informações acesse artig
Magnetic Ordering Of Eutepbte Multilayers Determined By X-ray Resonant Diffraction
In this work we use resonant x-ray diffraction combined with polarization analysis of the diffracted beam to study the magnetic ordering in EuTePbTe multilayers. The presence of satellites at the (1/2 1/2 1/2) magnetic reflection of a 50 repetition EuTePbTe superlattice demonstrated the existence of magnetic correlations among the alternated EuTe layers. The behavior of the satellites intensity as T increases toward the Ǹel temperature TN indicates that these correlations persist nearly up to TN and suggests the preferential decrease of the magnetic order parameter of external monolayers of each EuTe layer within the superlattice. © 2008 American Institute of Physics.9224Lovesey, S.W., Collins, S.P., (1996) X-Ray Scattering and Absorption by Magnetic Materials, , (Oxford University Press, New York)Granado, E., Pagliuso, P.G., Giles, C., Lora-Serrano, R., Yokaichiya, F., Sarrao, J.L., (2004) Phys. Rev. B, 69, p. 144411. , PRBMDO 0163-1829 10.1103/PhysRevB.69.144411Tonnerre, J.M., Seve, L., Raoux, D., Rodmacq, B., De Santis, M., Troussel, P., Brot, J.M., Chen, C.T., (1995) Nucl. Instrum. Methods Phys. Res. B, 97, p. 444. , NIMBEU 0168-583X 10.1016/0168-583X(94)00721-7Langridge, S., Stirling, W.G., Lander, G.H., Rebizant, J., (1994) Phys. Rev. B, 49, p. 12010. , PRBMDO 0163-1829 10.1103/PhysRevB.49.12010Leiner, V., Ay, M., Zabel, H., (2004) Phys. Rev. B, 70, p. 104429. , PRBMDO 0163-1829 10.1103/PhysRevB.70.104429Kepa, H., Springholz, G., Giebultowicz, T.M., Goldman, K.I., Majkrzak, C.F., Kacman, P., Blinowski, J., Bauer, G., (2003) Phys. Rev. B, 68, p. 024419. , PRBMDO 0163-1829 10.1103/PhysRevB.68.024419Binder, K., Hohenberg, P.C., (1974) Phys. Rev. B, 9, p. 2194. , PLRBAQ 0556-2805 10.1103/PhysRevB.9.2194Oliveira, N.F., Foner, S., Shapira, Y., Reed, T.B., (1972) Phys. Rev. B, 5, p. 2634. , PLRBAQ 0556-2805 10.1103/PhysRevB.5.2634Giles, C., Yokaichiya, F., Kycia, S.W., Sampaio, L.C., Ardiles-Saravia, D.C., Franco, M.K.K., Neuenschwander, R.T., (2003) J. Synchrotron Radiat., 10, p. 430. , JSYRES 0909-0495 10.1107/S0909049503020958Hol, V., Kubena, J., Ploog, K., (1990) Phys. Status Solidi B, 162, p. 347. , PSSBBD 0370-1972 10.1002/pssb.2221620204Nunez, V., Majkrzak, C.F., Springholz, G., Bauer, G., Giebultowicz, T.M., Kepa, H., Goldman, K.I., (1998) Superlattices Microstruct., 23, p. 41. , SUMIEK 0749-6036 10.1006/spmi.1996.0205Giebultowicz, T.M., Kepa, H., Blinowski, J., Kacman, P., (2001) Physica e (Amsterdam), 10, p. 411. , PELNFM 1386-9477 10.1016/S1386-9477(01)00128-
A diet rich in cocoa attenuates N-nitrosodiethylamine-induced liver injury in rats
The effects of cocoa feeding against N-nitrosodiethylamine (DEN)-induced liver injury were studied in rats. Animals were divided into five groups. Groups 1 and 2 were fed with standard and cocoa-diet, respectively. Groups 3 and 4 were injected with DEN at 2 and 4 weeks, and fed with standard and cocoa-diet, respectively. Group 5 was treated with DEN, received the standard diet for 4 weeks and then it was replaced by the cocoa-diet. DEN-induced hepatic damage caused a significant increase in damage markers, as well as a decrease in the hepatic glutathione, diminished levels of p-ERK and enhanced protein carbonyl content, caspase-3 activity and values of p-AKT and p-JNK. The cocoa-rich diet prevented the reduction of hepatic glutathione concentration and catalase and GPx activities in DEN-injected rats, as well as diminished protein carbonyl content, caspase-3 activity, p-AKT and p-JNK levels, and increased GST activity. However, cocoa administration did not abrogate the DEN-induced body weight loss and the increased levels of hepatic-specific enzymes and LDH. These results suggested that cocoa-rich diet attenuates the DEN-induced liver injury. © 2009 Elsevier Ltd. All rights reserved.This work was supported by the grants 200870I198, AGL2004-302, AGL2007-64042 and CSD2007-00063 from the Spanish Ministry of Science and Innovation. A.B. Granado-Serrano is a predoctoral fellow of the Spanish Ministry of Science and Education.Peer Reviewe
Magnetic ordering of EuTe/PbTe multilayers determined by x-ray resonant diffraction
In this work we use resonant x-ray diffraction combined with polarization analysis of the diffracted beam to study the magnetic ordering in EuTe/PbTe multilayers. The presence of satellites at the (1/2 1/2 1/2) magnetic reflection of a 50 /repetition EuTe/PbTe superlattice demonstrated the existence of magnetic correlations among the alternated EuTe layers. The behavior of the satellites intensity as T increases toward the Neel temperature T(N) indicates that these correlations persist nearly up to T(N) and suggests the preferential decrease of the magnetic order parameter of external monolayers of each EuTe layer within the superlattice. (C) 2008 American Institute of Physics.922
Spin-state ordering and intermediate states in the mixed-valence cobalt oxyborate CoOBO with spin crossover
Spin-state ordering - a periodic pattern of ions with different spin-state
configurations along a crystal lattice - is a rare phenomenon, and its possible
interrelation with other electronic degrees of freedom remains little explored.
Here we perform a structural investigation of the mixed-valence Co homometallic
ludwigite CoCoOBO. A superstructure consistent with a
long-range Co spin-state ordering is observed between K and
K. Intermediate states with mesoscopic correlations are detected
below down to K with a change of dimensionality at
K. The spin-state correlations are connected to the charge sector
as revealed by the abrupt changes in the electrical resistance at and
. The evolution of the structural parameters below indicate that
the spin crossover is ignited by a moderate degree of thermally-induced
Co/Co charge disorder. Charge and spin-state degrees of freedom
can be interrelated in mixed-valence spin-crossover materials, leading to sharp
transitions involving intermediate spin-state/charge correlated states at the
mesoscale.Comment: 28 pages, 8 figure
Magnetic structure and critical behavior of GdRhIn: resonant x-ray diffraction and renormalization group analysis
The magnetic structure and fluctuations of tetragonal GdRhIn5 were studied by
resonant x-ray diffraction at the Gd LII and LIII edges, followed by a
renormalization group analysis for this and other related Gd-based compounds,
namely Gd2IrIn8 and GdIn3. These compounds are spin-only analogs of the
isostructural Ce-based heavy-fermion superconductors. The ground state of
GdRhIn5 shows a commensurate antiferromagnetic spin structure with propagation
vector tau = (0,1/2, 1/2), corresponding to a parallel spin alignment along the
a-direction and antiparallel alignment along b and c. A comparison between this
magnetic structure and those of other members of the Rm(Co,Rh,Ir)n In3m+2n
family (R =rare earth, n = 0, 1; m = 1, 2) indicates that, in general, tau is
determined by a competition between first-(J1) and second-neighbor(J2)
antiferromagnetic (AFM) interactions. While a large J1 /J2 ratio favors an
antiparallel alignment along the three directions (the so-called G-AFM
structure), a smaller ratio favors the magnetic structure of GdRhIn5 (C-AFM).
In particular, it is inferred that the heavy-fermion superconductor CeRhIn5 is
in a frontier between these two ground states, which may explain its
non-collinear spiral magnetic structure. The critical behavior of GdRhIn5 close
to the paramagnetic transition at TN = 39 K was also studied in detail. A
typical second-order transition with the ordered magnetization critical
parameter beta = 0.35 was experimentally found, and theoretically investigated
by means of a renormalization group analysis.Comment: 22 pages, 4 figure
Existence of orbital polarons in ferromagnetic insulating LaSrMnO (0.110.14) evidenced by giant phonon softening
We present an inelastic light scattering study of single crystalline
(LaPr)SrMnO (, and
,). A giant softening up to 20 - 30 cm of the
Mn-O breathing mode has been observed only for the ferromagnetic insulating
(FMI) samples () upon cooling below the Curie
temperature. With increasing Pr-doping the giant softening is gradually
suppressed. This is attributed to a coupling of the breathing mode to orbital
polarons which are present in the FMI phase.Comment: 4 pages, 5 figure
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