A complex three dimensional network structure results when blood fibrin polymerizes into branching threads. To understand the rheological behavior of fibrin clots and how this behavior is associated with network morph...
A complex three dimensional network structure results when blood fibrin polymerizes into branching threads. To understand the rheological behavior of fibrin clots and how this behavior is associated with network morphology, one must obtain quantitative measurements of morphometric parameters of the networks (e.g., fiber diameter, distance between branching points of fibers, and branching complexity) formed under various conditions. Over the past several years, researchers have measured the parameters manually from the 3D reconstruction of networks using stereo images generated with intermediate voltage electron microscopy. Our goal is to help automate this time consuming process as much as possible, and skeletonization is a promising tool. Skeletonization is a process of transforming an object into idealized thin lines. Although various techniques for skeleton computation have been developed, most of them require explicit boundary information of the objects being skeletonized, which is not directly available from raw images.
The recently developed generalized linear least squares (GLLS) fast algorithm is useful in image-wide parameter estimation to generate parametric images with positron emission tomography (PET). However, parameter esti...
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The recently developed generalized linear least squares (GLLS) fast algorithm is useful in image-wide parameter estimation to generate parametric images with positron emission tomography (PET). However, parameter estimation using the GLLS may not converge for every pixel in noisy clinical PET data. In this study, a bound generalized linear least squares (B-GLLS) algorithm was proposed to guarantee that the estimation converges for noisy pixel curves and the parameters estimated are within the physiological and pathological ranges. The clinical results demonstrated that the B-GLLS algorithm can generate more accurate parametric images and is potentially useful in dynamic clinical PET studies.
In a psychophysical experiment, a wideband, 4-ms noise is compared with spectrally smoothed versions of the noise. To isolate on the magnitude spectrum, the phase spectrum is controlled by assigning the same random ph...
In biomedical ultrasound, it is often required to eliminate the spectral shaping caused by the transducer from the backscattered signal to obtain the pure tissue response for diagnostic purposes. Here, the authors dec...
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ISBN:
(纸本)0780364651
In biomedical ultrasound, it is often required to eliminate the spectral shaping caused by the transducer from the backscattered signal to obtain the pure tissue response for diagnostic purposes. Here, the authors deconvolve ultrasonic backscattered signals using a least squares deconvolution method in the wavelet domain. The ultrasonic echo is often modeled as the convolution of the transducer impulse response and the response of the medium. The authors solve this deconvolution problem by estimating a filter which approximates the inverse of the transducer impulse response. Therefore, applying this filter to the echo yields the tissue response and applying it to the transducer impulse response results in an impulse function. In this work, the authors assume that the tissue response exhibits 1/f type spectral behavior. Hence, they use the wavelet transform in the deconvolution algorithm for the 1/f signals, which has the useful property that the logarithm of the variance of the wavelet coefficients in each stage progresses linearly. Initially the authors estimate a rough inverse filter using the transducer impulse response. Then, they optimize this filter by minimizing an error criterion defined by using the linear progression property of the logarithmic variance of the wavelet coefficients for the 1/f signals. The authors present the error minimization algorithm and the deconvolution results for tissue mimicking phantom data.
We present a parallel model based on Cellular Automata for the simulation of reaction–diffusion processes, that has been applied to the percolation of pesticides in the soil. The main contribution of our approach con...
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Scheduling jobs with pairwise conflicts is modeled by the graph multi-coloring problem. It occurs in two versions: preemptive and non-preemptive. We study these problems on trees under the sum-of- completion-times obj...
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Little is known on the perceptual processes of speaker identification and its relations to the acoustic features of the speaker's voice. A study of speaker perception and identification by psycho-acoustic experime...
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作者：
Afrati, F.Bampis, E.Kenyon, C.Milis, I.NTUA
Division of Computer Science Heroon Polytechniou 9 Athens15773 Greece LaMI
University d’Evry Boulevard Francois Mitterrand Evry Cedex91025 France LRI
Bat 490 Universite Paris-Sud Orsay Cedex91405 France Athens University of Economics
Dept. of Informatics Patission 76 Athens10434 Greece
We consider the problem of scheduling independent jobs on a constant number of machines. We illustrate two important approaches for obtaining polynomial time approximation schemes for two different variants of the pro...
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