Alternate generation or metagenesis is that kind of multiplication, seen in some invertebrate animals or even in plants, in which parents produce progeny unlike, sometimes extremely unlike, themselves, while this unlike progeny give rise to others resembling the original forms. Sometimes there are more than one unlike form between these like forms. The Hydrozoa abundantly illustrate this phenomenon, also the Echinoderms, Polyzoa, Tunicata, the wheel animalcules, Nematoid worms, flat-worms, tape-worms, several of the true Annelids; among Crustaceans, Daphnia, the Phyllopods; among Insects, the plant-lice.
The steps may be seen in certain of the Hydroid Polyps, thus: (1) There is an ovum or egg, free-swimming and impregnated. (2) This ovum attaches itself to a fixed submarine object, and develops into an organized animal. (3) This organism produces buds or zooids, often of two kinds - one set nutritive, the other generative - unlike each other and unlike their parent, the whole forming a hydroid colony. (4) The generative set mature eggs, which on being liberated become the free-swimming ova (No. 1), and the cycle is renewed. A somewhat similar phenomenon is that of parthenogenesis. Research Alternate Generation
Echinococcus is one of the larval forms (scolices) of the tape-worm of the dog (Toenia Echinococcus), which may occur in man and cause serious disease. Research Echinococcus
Flukes, or fluke-worms is a name given to certain parasitic Scolecida (tape-worms, etc), belonging to the division of Platyelmia or Flat-worms, and included in the order Trematoda. They inhabit various situations in different animals - mostly in birds and fishes. The Distoma hepaticum exists in large numbers in the livers of sheep, and causes the disease known as 'rot' . Like the tape-worms the flukes pass through an elaborate development. Research Fluke
Delia Derbyshire was a British composer and the inspiration behind modern electronic music. She died in 2001. As a studio manager at the BBC, working in the radiophonic workshop she arranged the theme tune for the 1960's television series 'Dr Who' from a few suggested notes passed to her on a scrap of paper by her boss. Delia Derbyshire composed music from adjusting sounds she found in everyday life, such as a metal lamp shade being struck by a stick, or a key run along a piano string, a sound which features in the Dr Whotheme tune, recording these sounds onto short pieces of tape, and splicing them, adjusting the speed at which they were played and playing them backwards to produce revolutionary new sounds, all without the benefit of computers or synthesisers. Research Delia Derbyshire
Milton Byron Babbitt is an American composer. He was born in 1916 at Philadelphia. He studied with the American composer Roger Sessions and joined the Princeton University faculty in 1938, and in 1959 he helped found the Columbia-Princeton Electronic Music Center. In 1982 he was awarded a Pulitzer Special Citation for his life's work. His works include 'Philomel' written in 1964, for soprano and magnetic tape, and 'Concerti for Violin, Small Orchestra', and the 1976 Synthesized Tape. Research Milton Byron Babbitt
Acrylamide is an odourless, free-flowing white crystalline used as a chemical intermediate in the production and synthesis of polyacrylamides. These high-molecular weight polymers can be modified to develop non-ionic, anionic, or cationic properties for specific uses. The principle end use of
acrylamide is in water-soluble polymers used as additives for water treatment, enhanced oil recovery, flocculants, papermaking aids, thickeners, soil conditioning agents, sewage and waste treatment, ore processing, and permanent press fabrics.
Acrylamide is also used in the synthesis of dyes, in copolymers for contact lenses, and the construction of damfoundations, tunnels, and sewers. The largest use for polyacrylamide is in treating municipal drinking water and wastewater. The polymer is also used to remove suspended solids from industrial wastewater before discharge, reuse, or disposal.
Acrylamides also find use in oil-drilling processes to control fluid losses. In the pulp and paper industry, polyacrylamides are used as binders and retention aids for fibres and to retain pigments on paper fibres.
Acrylamide is a soil stabiliser and also finds use in foundry operations to facilitate free sand flow into moulds. Home appliances, building materials, and automotive parts are coated with acrylamide resins and thermosetting acrylics. Acrylamides are formulated in cosmetics and soap preparations as thickeners and in dental fixtures, hair grooming preparations, and pre-shave lotions. Minor uses of acrylamide are as latex thickeners, emulsion stabilisers for printing inks, gelling agents for explosives, binders in adhesives and adhesive tape, in the production of diazo compounds, and for gel chromatography and electrophoresis.
Acrylamide occurs in crystalline form and in aqueous solution. It is soluble in water, methanol, ethanol, dimethyl ether, and acetone; it is insoluble in benzene and heptane. The monomer readily polymerises at the melting point or under ultraviolet light. Solid acrylamide is stable at room temperature, but may polymerise violently when melted or in contact with oxidising agents such as chlorine dioxide and bromine. When heated to decomposition, acrylamide emits a poisonous gas, acrid fumes, and NOx. If heating to high temperatures, acrylamide can explode. Acrylamide is also known as
acrylamide monomer, acrylic amide, propenamide, and 2-propenamide. Research Acrylamide
Diethyl phthalate is a manufactured, colourless, oily liquid with a slight aromatic odour and a bittertaste. It is commonly used to make plastics more flexible, in products such as toothbrushes, automobile parts, tools, toys, and food packaging. It is also used in insecticides, mosquito repellents, aspirin, and cosmetics, including bath preparations, eye shadows, hair sprays, wave sets, nailpolish, nailpolish remover, nail extenders, detergents, aftershave lotions, and skin care preparations. Diethyl phthalate is used to manufacture celluloid; as a solvent for cellulose acetate in varnishes; as a fixative for perfumes; as a wetting agent; as a camphor substitute; as a dilutent in polysulphide dental impression materials; and as a solvent for nitrocellulose and cellulose acetate. It is used as a plasticizer in solid rocket propellants and celluloseester plastics such as photographic films and sheets, blister packaging, and tape applications.
Diethyl phthalate is soluble in alcohol, ether, acetone, benzene, vegetable oils, ketones, esters, aromatic hydrocarbons, and aliphatic solvents. It is compatible with polar polymers and additives over a wide range of compositions. When heated to decomposition, it emits acrid smoke.
Diethyl phthalate is also known as 1,2-benzenedicarboxylic acid diethyl ester; ethyl phthalate; diethyl o-phthalate; o-benzenedicarboxylic acid diethyl ester; diethyl ester phthalic acid; phthalol; DEP; and diethyl-o-phenylenediacetate. Research Diethyl phthalate
Magnetic recording originated in 1899 with the invention by Valdemar Poulsen of the Telegraphone. During the period between the two World Wars, development work was carried out which resulted in improved systems, notable among which were the Blattnerphone and the Marconi-Stille. These systems employed a steel tape as the recording medium, a material which was bulky and difficult to handle. Mechanical and magnetic requirements were often mutually exclusive. The jointing of sections was also difficult. In 1928, Dr. Pfleumer took out a patent in Germany for a new and much improved medium. This consisted of a paper or plastic base tape, having most of the required mechanical properties, on which was deposited a very thin coating of powdered magnetic material. A later patent (in 1935) introduced oxide of iron as the magnetic medium. This oxide, though not ideal in its magnetic properties, was a considerable improvement on the steel tapes previously available. During the Second World War, considerable development work was carried out in Germany, resulting in a system of recording sound magnetically which ranked with the best on disc or film. Concurrently, in the USA, the problem of the bulk of the steel tapes had been overcome by utilizing a, thin steel wire, normally 0.004 inches in diameter. As with the Magnetophon tape, the reduction of material available for recording upon was offset by improvements in other factors. Up to 1946 the greater part of the development work had been carried out empirically. Since that date, however, considerable research has been undertaken into the causes underlying the observed results. Due to this research, a number of improvements has been made possible, and within the standards of current practice, magnetic tape recording shows superiority over both disc and film recording. In fact, it is now the normal practice for commercial disc and film recordings to be made through an intermediate magnetic recording process, without any noticeable loss of quality in the finished product. Even a trained ear has difficulty in distinguishing a good magnetic
tape recording from the original sound reproduced over the same amplifier/loudspeaker system. Quite small and compact recorders, suitable for domestic use, while they cannot compete with the larger professional machines, are capable of a, remarkably high quality of reproduction. Wire recording has not proved itself capable of such a high standard of quality as tape, but has met a need for a very small, light and compact recording machine, suitable for the intelligible recording of speech for long runs of an hour or more. Domestic models were also available, but didn't catch on, the domestic market preferring magnetic tape. So far as is known, magnetic recordings are permanent if properly stored. However, they have the outstanding advantage, particularly in the domestic and computer fields, that the recording can be erased at will and the material re-used as often as desired. Tape may be cut and joined with precision, on a syllable of speech or a note in music. Since the late 1990s digital recording with computers has started to replace tape splicing for
editing
magnetic recordings, but although recordings are carried out digitally using computers, the computers' disk drives still use magnetic material for the recording. Research Magnetic Recording
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Gaffer Tape
