منابع مشابه
Ross procedure at the crossroads.
The quest for a perfect heart valve substitute has been going on for half a century. In 1960, Lower et al1 described the feasibility of replacing the aortic valve of dogs with the native pulmonary valve. In 1967, Ross performed this procedure in humans.2 Ross transferred the pulmonary valve into the aortic root with the same technique used to implant aortic valve homograft3 (ie, the pulmonary s...
متن کاملDynamical x-ray reflection at terraces in epitaxial layers
Terrace formation in semiconductor epitaxial layers has been postulated to cause lattice bending, which ought to be observable by x-ray diffraction. Consideration of dynamical effects of x-ray reflection, both at the terraces and from a distorted crystal lattice, shows that diffraction effects by far outweigh the effects oflattice bending. For a given liquid phase epitaxial GaAs layer on a GaAs...
متن کاملFractal terraces in MBE growth
MBE growth on high symmetry surfaces depends to some extent on the shape of the terraces which form the embryos of each new atomic layer. The conditions for formation of compact or fractal terraces are discussed in two limits: large terraces, to which a continuous description applies, and small terraces, which require that the discrete nature of matter be taken into account. In both cases it is...
متن کاملTerraces in phylogenetic tree space.
A key step in assembling the tree of life is the construction of species-rich phylogenies from multilocus--but often incomplete--sequence data sets. We describe previously unknown structure in the landscape of solutions to the tree reconstruction problem, comprising sometimes vast "terraces" of trees with identical quality, arranged on islands of phylogenetically similar trees. Phylogenetic amb...
متن کاملAn Extension Theorem for Terraces
We generalise an extension theorem for terraces for abelian groups to apply to nonabelian groups with a central subgroup isomorphic to the Klein 4-group V . We also give terraces for three of the non-abelian groups of order a multiple of 8 that have a cyclic subgroup of index 2 that may be used in the extension theorem. These results imply the existence of terraces for many groups that were not...
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ژورنال
عنوان ژورنال: Transactions of the Edinburgh Geological Society
سال: 1887
ISSN: 0371-6260,2052-9414
DOI: 10.1144/transed.5.2.275