Unit of reciprocal inductance henry back
The direction in which a series of inclined sedimentary rocks becomes younger. See way up.
A silicate of aluminium, iron and magnesium, crystallizing in the monoclinic system,
A large tow-net the mouth of which is kept open by otter boards, used for capturing small fishes at the surface or in mid-water. Also Yngel trawl.
Yeasts are simple microbial eukaryotes with several features making them highly suitable for genetical and biochemical studies, esp of fundamental cellular processes. Two species, Saccharomyces cerevisiae and Schizosaccharomyces pom he have been most used. In these and some others, both haploid and diploid cells can proliferate by vegetative growth but a sexual system is also present, with mating between haploid cells leading to nuclear fusion and the formation of a diploid nucleus. The resulting diploid cell can enter meiosis under suitable conditions, leading to the formation of four haploid progeny spores. Each spore can germinate and form a colony of cells with identical genotypes, allowing the progeny of a cross to be analysed. Thus yeasts behave genetically like higher eukaryotes, classical genetic procedures being readily carried out with the major advantage that all four spores from a single meiosis can be micro-dissected apart, allowing sophisticated analysis. Some mutants have simple biochemical defects, resulting in a failure to grow in the absence of particular components in the growth medium; others are unable to use certain carbon or nitrogen sources for growth. Temperature sensitive mutants, defective in central cellular processes, have also been obtained.
The yolk-containing sac which is attached to the embryo by the yolk stalk in certain forms.
A marine water-tube boiler employing an upper steam drum connected by banks of inclined tubes to three lower water drums, between two of which susperheating elements are arranged,
A massive, granular or earthy mineral, essentially a cerian fluorite, with the metals of the yttrium and cerium groups, commonly violet-blue in colour, and of rare occurrence.
The amount of plastic strain which occurs at constant or decreasing load in metals which exhibit a pronounced
The lateral, or pitch, axis of an aircraft. Cf axis,