| 1. |
- Nordén, Bengt, 1945
(författare)
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The asymmetry of life
- 1978
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Ingår i: Journal of Molecular Evolution. - : Springer Science and Business Media LLC. - 1432-1432 .- 0022-2844. ; 11:4, s. 313-332
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Tidskriftsartikel (refereegranskat)abstract
- Stereoselective physical phenomena and their possible importance for the prevalence of D-sugars and L-aminoacids in living matter are reviewed. A classification is presented according to which a selective force provides a microscopic or macroscopic selection depending on its generality when taken over a macrosystem (a lsquounitary biospherersquo such as the Earth). The microscopic lsquoselectionsrsquo are not genuine selections because the final sense of asymmetry is here determined by chance, in other words the initial choice is lsquorandomrsquo, while it is lsquodirectedrsquo in the macroscopic selection. Two macroscopic selections appear possible:1. selection due to an intrinsic energy difference between enantiomorph configurations, 2. selection accomplished by elliptically polarised radiation.
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| 2. |
- Easterling, K.E.
(författare)
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Metallurgical applications of scanning transmission electron microscopy
- 1977
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 12:5, s. 857-868
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that scanning transmission microscopy (STEM) has followed two main lines of development, the pure STEM based upon a field emission electron source in which the emphasis is given to high resolution, and a combined system in which STEM is an attachment to a conventional transmission microscope (TEM+STEM). When used in combination with an energy dispersive X-ray spectrometer, the combined TEM+STEM system is shown to be extremely versatile and possibly the more useful for the applied metallurgist. The high vacuum requirements of pure STEM, however, make this system suitable to be used in conjunction with an Auger spectrometer. Examples of the various microanalysis facilities of STEM are given in the article, including micro-diffraction, rocking-beam channelling patterns, qualitative and quantitative X-ray spectroscopy analysis, particle analysis, and in situ experimentation. The controversial subject of whether thicker specimens can be studied in STEM compared with conventional TEM is also discussed
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| 3. |
- Glad, Torkel, 1947-
(författare)
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Properties of Updating Methods for the Multipliers in Augmented Lagrangians
- 1979
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Ingår i: Journal of Optimization Theory and Applications. - : Kluwer Academic Publishers. - 0022-3239 .- 1573-2878. ; 28:2, s. 135-156
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Tidskriftsartikel (refereegranskat)abstract
- The convergence properties of different updating methods for the multipliers in augmented Lagrangians are considered. It is assumed that the updating of the multipliers takes place after each line search of a quasi-Newton method. Two of the updating methods are shown to be linearly convergent locally, while a third method has superlinear convergence locally. Modifications of the algorithms to ensure global convergence are considered. The results of a computational comparison with other methods are presented.
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