An absorbing mystery
Article Abstract:
The amount of solar radiation absorbed by the atmospheric clouds is more than that which is predicted by the current atmospheric models. According to these findings, the increased absorption is mainly in the summers in the tropic and sub-latitude regions and is variable at all latitudes. It has also been suggested that the burning biomass produces aerosols which increase absorption. The US Atmospheric Radiation Measurement program has decided to carry out a month long project to test this theory of increased atmospheric absorbtion in fall 1995 and spring 1996.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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Phase-contrast imaging using polychromatic hard X-rays
Article Abstract:
A simplified technique for phase-contrast imaging is based on a conventional polychromatic hard X-ray source that has high spatial coherence. This technique is useful for samples that have rapid variation in thickness or refractive index. It allow a large amount of magnification and is suitable for large areas of irradiation. The method of obtaining phase-contrast with polychromatic X-ray sources can generate X-ray images of even very weakly absorbing material.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Phase-contrast imaging of weakly absorbing materials using hard X-rays
Article Abstract:
Resolving phase variations across the X-ray beam increases the contrast in the images of hard x-rays, making it more applicable as a diagnostic tool. Diffraction properties of a perfect silicon crystal help determine the phase gradients and spatial resolution. Contract reversal is observed in the phase-contrast images recorded in bright and dark fields.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1995
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