1,317 research outputs found
Probabilistic Motion Estimation Based on Temporal Coherence
We develop a theory for the temporal integration of visual motion motivated
by psychophysical experiments. The theory proposes that input data are
temporally grouped and used to predict and estimate the motion flows in the
image sequence. This temporal grouping can be considered a generalization of
the data association techniques used by engineers to study motion sequences.
Our temporal-grouping theory is expressed in terms of the Bayesian
generalization of standard Kalman filtering. To implement the theory we derive
a parallel network which shares some properties of cortical networks. Computer
simulations of this network demonstrate that our theory qualitatively accounts
for psychophysical experiments on motion occlusion and motion outliers.Comment: 40 pages, 7 figure
Localization Properties of Quantized Magnetostatic Modes in Nanocubes
We investigate the dynamical properties of a system of interacting magnetic
dipoles disposed in sites of an sc lattice and forming a cubic-shaped sample of
size determined by the cube edge length (N-1)a (a being the lattice constant, N
representing the number of dipolar planes). The dipolar field resulting from
the dipole-dipole interactions is calculated numerically in points of the axis
connecting opposite cube face centers (central axis) by collecting individual
contributions to this field coming from each of the N atomic planes
perpendicular to the central axis. The applied magnetic field is assumed to be
oriented along the central axis, magnetizing uniformly the whole sample, all
the dipoles being aligned parallelly in the direction of the applied field. The
frequency spectrum of magnetostatic waves propagating in the direction of the
applied field is found numerically by solving the Landau-Lifshitz equation of
motion including the local (nonhomogeneous) dipolar field component; the mode
amplitude spatial distributions (mode profiles) are depicted as well. It is
found that only the two energetically highest modes have bulk-extended
character. All the remaining modes are of localized nature; more precisely, the
modes forming the lower part of the spectrum are localized in the subsurface
region, while the upper-spectrum modes are localized around the sample center.
We show that the mode localization regions narrow down as the cube size, N,
increases (we investigated the range of N=21 to N=101), and in sufficiently
large cubes one obtains practically only center-localized and surface-localized
magnetostatic modes.Comment: 20 pages, 9 figures in postscript, useing Revtex4.cl
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Oncogenic Gain of Function in Glioblastoma Is Linked to Mutant p53 Amyloid Oligomers.
Tumor-associated p53 mutations endow cells with malignant phenotypes, including chemoresistance. Amyloid-like oligomers of mutant p53 transform this tumor suppressor into an oncogene. However, the composition and distribution of mutant p53 oligomers are unknown and the mechanism involved in the conversion is sparse. Here, we report accumulation of a p53 mutant within amyloid-like p53 oligomers in glioblastoma-derived cells presenting a chemoresistant gain-of-function phenotype. Statistical analysis from fluorescence fluctuation spectroscopy, pressure-induced measurements, and thioflavin T kinetics demonstrates the distribution of oligomers larger than the active tetrameric form of p53 in the nuclei of living cells and the destabilization of native-drifted p53 species that become amyloid. Collectively, these results provide insights into the role of amyloid-like mutant p53 oligomers in the chemoresistance phenotype of malignant and invasive brain tumors and shed light on therapeutic options to avert cancer
NJL-type models in the presence of intense magnetic fields: The role of the regularization prescription
We study the regularization dependence of the Nambu-Jona-Lasinio model (NJL) predictions for some properties of magnetized quark matter at zero temperature (and baryonic density) in the mean field approximation. The model parameter dependence for each regularization procedure is also analyzed in detail. We calculate the average and difference of the quark condensates using different regularization methods and compare with recent lattice results. In this context, the reliability of the different regularization procedures is discussed.Fil: Avancini, Sidney S.. Universidade Federal Da Santa Catarina. Cent.de Cs Físicas E Matemáticas; BrasilFil: Farias, Ricardo L. S.. Universidade Federal de Santa Maria; BrasilFil: Scoccola, Norberto Nerio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina. Universidad Favaloro. Facultad de Ingeniería y Ciencias Exactas y Naturales; ArgentinaFil: Tavares, William R.. Universidade Federal Da Santa Catarina. Cent.de Cs Físicas E Matemáticas; Brasi
Coexistence of halloysite and kaolinite: a study on the genesis of kaolin clays of Campo Alegre Basin, Santa Catarina State, Brazil
Kaolin at Campo Alegre Basin, Santa Catarina State, Brazilwas formed from alteration of volcanic acid rocks. Halloysite
clays dominate the clay fraction of the matrix of the kaolin body, whereas a poorly crystalline kaolinite is abundant
in veins. Some primary blocky structures have high amounts of illite, in one mine, but in general, only low contents
of illite-smectite, illite, chlorite-vermiculite, vermiculite and quartz were identified in the clay fraction of the samples.
Toward the top of the mines, hematite and lepidocrocite appear in horizontal red and ochre colored levels and the amount
of kaolinite increases compared to halloysite. The vertical zoning of alteration levels, the changes in mineralogy, the
positive correlation between depth and Cation Exchange Capacity of the clays, the preservation of different types of
rock textures in the kaolin bodies, the dominant tube morphology of the halloysite clays indicate a supergene genesis
for the deposits. Criteria to distinguish between supergene and hypogene kaolin are discussed. Transmission Electron
Microscopy of the cross sections of halloysite tubes showed polygonal forms that are ascribed to be transitional between
kaolinite and halloysite. It is proposed that some of the kaolinite of these deposits be inherited from the dehydration of
halloysite tubes
Hyperon Polarizabilities in the Bound State Soliton Model
A detailed calculation of electric and magnetic static polarizabilities of
octet hyperons is presented in the framework of the bound state soliton model.
Both seagull and dispersive contributions are considered, and the results are
compared with different model predictions.Comment: 19 pages, plain Latex, no figure
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