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The purpose of the present paper is to review the current knowledge about cholesterol gallstone disease. It is generally accepted that the formation of cholesterol gallstone requires three major pathogenic defects, namely, supersaturation, nucleation and crystal growth as well as…

These notes contain a series of ten lectures delivered at the ''Universidad Nacional Autonoma de Mexico'' on its ''Primer Seminario de K-Teoria Algebraica''. They provide an introduction to the subject as well as to the other expositions in this volume.…

The compressed basidiocarp of a fungus belonging to Geasteraceae (Lycoperdales, Gasteromycetes) was recovered from the plant-bearing Cenozoic strata of the Pie de Vaca Formation, Puebla, Mexico. The fossil specimen consists of an open exoperidium with ten triangular rays, and a…

Mimosoideae), Mimosa (Mimoseae, Mimosoideae), Lysiloma (Ingeae, Mimosoideae),and Sophora (Sophoreae, Papilionoideae). Another fruit exhibits a combination of characters unknown among extant legumes, and although superficially similar to some species of Papilionoideae, it represents an extinct genus. The four identified genera are…

The Upper Cenozoic flora of the Pie de Vaca Formation, Puebla, Mexico, is yielding important elements that contribute to a more complete knowledge of the Tertiary floras of southern latitudes of North America. Among the most abundant plant organs in…

Diabetes mellitus is a syndrome which affects more and more people in all countries over the world. In Mexico, it is commonly treated with herbal extracts. Such treatment may be of considerable benefit especially during the early stages of the…

Early in the twentieth century it was shown that Mendel's laws apply to plants and animals and that genes reside on chromosomes. In the 1950s the double-helix model of DNA inaugurated the molecular biology era, which culminated at the end…

A new terrestrial species of Pseudoeurycea is described from the mountains of the Mixteca region of Oaxaca. Compared with other members of the genus, the new species is relatively slender and short-legged. The background color of the dorsum of this…

A new tertiary stibine and bismuthine containing C-heterocyclic selenophene ring have been synthesized. Tris(2-selenophenyl)stibine (1) and tris(2-selenophenyl) bismuthine (2) and characterized by IR, MS, H-1, C-13, COSY, HETCOR NMR spectroscopy. Crystal structures of stibine and bismuthine have been determined. In…