| lethal coefficient | <microbiology> That concentration of disinfectant that kills bacteria at 20-25캜 in the shortest period of time. (05 Mar 2000) |
|---|---|
| lethal dwarfism | Dwarfism leading to intrauterine or neonatal death. (05 Mar 2000) |
| lethal equivalent | A combination of selective effects that on average have the same impact on the composition of the gene pool as one death; e.g., two carriers at 50% risk of dying would be the lethal equivalent of one carrier at 100% risk, in the population genetics of recessive traits lethal equivalent is expressed as twice the sum of the expected number of deaths ascribable to the genetic load. Expression used of the genetic load of recessive genes in heterozygous state that if in homozygous state would cause death or carry a risk of death. The expected number of deaths from all such genes is expressed in lethal equivalent. (05 Mar 2000) |
| lethal factor | A disorder that prevents effective reproduction by those affected; e.g., Klinefelter syndrome. (05 Mar 2000) |
| lethal gene | A gene that produces a genotype that leads to death of the organism before reproduction is possible or that precludes reproduction; for a recessive gene the homozygous or hemizygous state is lethal. (05 Mar 2000) |
| lethal midline granuloma | Destruction of the nasal septum, hard palate, lateral nasal walls, paranasal sinuses, skin of the face, orbit and nasopharynx by an inflammatory infiltrate with atypical lymphocytic and histiocytic cells; presumably a form of lymphoma in most cases. An obsolete term for polymorphic reticulosis. Synonym: granuloma gangrenescens, malignant granuloma, midline malignant reticulosis granuloma. (05 Mar 2000) |
| lethal mutation | <genetics, molecular biology> Mutation that eventually results in the death of an organism carrying the mutation. (18 Nov 1997) |
| arithmetic mean | The mean calculated by adding a set of values and then dividing the sum by the number of values. (05 Mar 2000) |
| calculated mean organism | A hypothetical organism whose characters are the means of both the positive and negative characters of the organism's which belong to the same taxon as the CMO, as opposed to the hypothetical mean. Organism. (05 Mar 2000) |
| geometric mean | The mean calculated as the antilogarithm of the arithmetic mean of the logarithms of the individual values; it can also be calculated as the nth root of the product of n values. (05 Mar 2000) |
| geometric mean diameter | A measure of the central tendency of particle size composition of substrate materials sometimes used as an index of the quality of spawning gravels. Also referred to as D50 size. (09 Oct 1997) |
| mean | <statistics> Average value calculated by taking the sum of all values and dividing by the total number of values. (05 Jan 1998) |
| mean annual increment | The annual average growth rate for a tree, computed over its entire life cycle. (05 Dec 1998) |
| mean arterial pressure | <cardiology, physiology> The average value for arterial pressure. Systolic pressure + diastolic pressure divided by 2. (27 Sep 1997) |
| mean calorie | One hundredth of the energy required to raise the temperature of 1 g of water from 0캜 to 100캜. (05 Mar 2000) |