| volume unit | A unit of a logarithmic scale for expressing the power level of a complex audio-frequency electrical signal, such as that transmitting music or speech; the power in volume unit's equals the decibels of power above a reference level of one milliwatt, as measured with an appropriate meter. (05 Mar 2000) |
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| respiratory care unit | The hospital unit in which patients with respiratory conditions requiring special attention receive intensive medical care and surveillance. (12 Dec 1998) |
| riboflavin unit | Potency usually expressed in terms of weight of pure riboflavin. See: Sherman-Bourquin unit of vitamin B2. Synonym: vitamin B2 unit. (05 Mar 2000) |
| chlorophyll unit | The number of chlorophyll molecules required to reduce one molecule of carbon dioxide by photosynthesis. (05 Mar 2000) |
| meter-kilogram-second unit | An absolute unit of the meter-kilogram-second system. (05 Mar 2000) |
| chorionic gonadotropin unit | The specific gonadotropic activity of 0.1 mg of the standard preparation of chorionic gonadotropin originating from the urine or placentas of pregnant women. (05 Mar 2000) |
| phosphatase unit | See: Bodansky unit, King unit. (05 Mar 2000) |
| photosynthetic unit | <biochemistry, plant biology> Group of photosynthetic pigment molecules (chlorophylls and carotenoids) that supply light to one reaction centre in photosystem I or II. (18 Nov 1997) |
| physiologic unit | The ultimate (hypothetical) vital unit of protoplasm, as conceived by Spencer, the smallest division of an organ that will perform its function; e.g., the uriniferous tubule. (05 Mar 2000) |
| colony-forming unit | <cell biology> An individual cell which is able to clone itself into an entire colony of identical cells. Irradiated mice can have their immune systems reconstituted by the injection of bone marrow cells from a nonirradiated animal. The injected cells form colonies in the spleen (hence s), each colony representing the progeny of a pluripotent stem cell. Operationally, therefore, the number of colony-forming units is a measure of the number of stem cells. Acronym: CFU (09 Oct 1997) |
| motor unit | A single somatic motor neuron and the group of muscle fibres innervated by it. (05 Mar 2000) |
| complement unit | The smallest amount (highest dilution) of complement that will cause haemolysis of a unit of red blood cells in the presence of a haemolysin unit. Synonym: alexin unit. (05 Mar 2000) |
| plaque-forming unit | <virology> Number of infectious virus particles or Ig producing cells per unit volume. See: plaque assay. <microbiology> Refers to any entity which can give rise to a plaque. For example: if a phage stock solution has 1010 pfu/ml, it means that every ml of this stock has 1010 phage particles which can form plaques. This (pfu/ml) is the conventional way to refer the concentration of a phage preparation. Compare: CFU. (10 Oct 1997) |
| mouse unit | The quantity of oestrogen capable of producing in a spayed mouse a characteristic change in the vaginal epithelium, namely, disappearance of leukocytes and appearance of cornified cells, as determined by a vaginal smear; equal approximately to one-half of an estrone unit. Synonym: mouse unit. (05 Mar 2000) |
| Corner-Allen unit | A unit of progestational activity, measured in rabbits; the minimum dose which, divided into five equal daily portions, produces on the sixth day the uterine changes characteristic of the eighth day of normal pregnancy; the unit has about the same potency as the international unit. (05 Mar 2000) |