Results 261 to 270 of about 1,449,260 (305)

MULCh: modules for the analysis of small-angle neutron contrast variation data from biomolecular assemblies

Journal of Applied Crystallography, 2008
Small-angle neutron scattering with contrast variation can fill important gaps in our understanding of biomolecular assemblies, providing constraints that can aid in the construction of molecular models and in subsequent model refinements.
Andrew E Whitten, Jill Trewhella
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Variation on Zernike’s phase-contrast microscope

Applied Optics, 2000
We describe the design, construction, and testing of a variant of Zernike's phase-contrast microscope. The sample is illuminated with a white-light source through an annular aperture, which is projected onto the entrance pupil of the objective lens. In the return path the light diffracted by the sample and appearing in the interior of the objective's ...
R, Liang, J K, Erwin, M, Mansuripur
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Analysis of variations in contrast‐detail experiments

Medical Physics, 1984
Three sources of variability in a contrast‐detail (CD) experiment have been quantitated: within‐observer variance, between‐observer variance, and sample variance. It is concluded that (1) it is more efficient to increase the numbers of replicated images and observers than to increase the number of readings; (2) sampling and between‐observer variations ...
G, Cohen, D L, McDaniel, L K, Wagner
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Automatic contrast enhancement by variational minimax optimization

2015 IEEE International Conference on Image Processing (ICIP), 2015
We present an automatic global contrast enhancement method using variational optimization. A novel energy functional is formulated as a convex combination of histogram equalization and quadratic distortion constraint regularization. The desired image gray-level transformation is obtained through minimax optimization.
Yongjian Yu, Jue Wang 0005
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The scattering at zero angle in contrast variation

The Journal of Chemical Physics, 1991
The scattering of neutrons, x-rays, or light by a polydisperse system of particles is studied. As is well known, for fixed wave vector q the scattering intensity I(q) is a quadratic function of the scattering length density of the external medium. The minimum of the parabola is the minimal scattering intensity Imin(q).
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Variational Image Fusion with Optimal Local Contrast

Computer Graphics Forum, 2015
AbstractIn this paper, we present a general variational method for image fusion. In particular, we combine different images of the same subject to a single composite that offers optimal exposedness, saturation and local contrast. Previous research approaches this task by first pre‐computing application‐specific weights based on the input, and then ...
David Hafner, Joachim Weickert
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On the variation of stacking fault contrast with crystal thickness

Physica Status Solidi (a), 1971
An investigation of the dependence of stacking fault contrast on crystal thickness in f.c.c. cobalt has shown that the effects of systematic reflections can change markedly with crystal thickness and defect depth. When the (111) set of systematic reflections was excited, the results showed that good agreement was obtained between the two beam theory ...
S. S. Sheinin, K. Z. Botbos
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AGE VARIATIONS IN NORMAL HUMAN CONTRAST SENSITIVITY

Acta Ophthalmologica, 1979
The visual contrast sensitivity (the reciprocal of contrast threshold) was studied as a function of age. Psychophysical measurements of binocular and monocular contrast thresholds were made for 33 normal observers at spatial frequencies within the range 0.5 to 40 cycles/degree.
G, Derefeldt, G, Lennerstrand, B, Lundh
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Spatiotemporal variation of chromatic and achromatic contrast thresholds

Journal of the Optical Society of America, 1983
Moving the retinal image of a sinusoidal grating at a constant velocity (compensated for eye movements) provides controlled spatial and temporal frequencies at every point in the stimulus field. Using this controlled-velocity technique, we have measured the detection threshold for isoluminance, red/green gratings as a function of their spatial and ...
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