| transmission threshold | <epidemiology> Occurs for a parasite when the basic reproductive rate Ro is equal to 1. Below this threshold level the disease is unable to maintain itself within the host population. Typically, for directly transmitted parasites there is a transmission threshold for the host population size. (05 Dec 1998) |
|---|---|
| transovarial transmission | Passage of parasites or infective agents from the maternal body to eggs within the ovaries; commonly used to describe certain arthropods, to explain the ability of larvae of the next generation to transmit disease pathogens, as with the infection of larval mites or ticks with rickettsiae or viruses. (05 Mar 2000) |
| transstadial transmission | Passage of a microbial parasite, such as a virus or rickettsia, from one developmental stage (stadium) of the host to its subsequent stage or stages, particularly as seen in mites. See: transovarial transmission. (05 Mar 2000) |
| acetyl reduction assay | <investigation> A technique for measuring the nitrogen fixation activity in photosynthetic organisms. It uses a flame ionisation detector and a gas chromatography apparatus to determine the reduction of acetylene to ethylene by the enzyme nitrogenase. (06 May 1997) |
| reduction | <orthopaedics, surgery> The correction of a fracture, dislocation or hernia. (18 Nov 1997) |
| reduction deformity | Congenital absence or attenuation of one or more body parts; usually of the limbs or limb components. (05 Mar 2000) |
| reduction division | The first cell division in meiosis, the process by which germ cells are formed. A unique event in which the chromosome number is reduced from diploid (46 chromosomes) to haploid (23 chromosomes). Also called first meiotic division or first meiosis. (12 Dec 1998) |
| reduction en masse | Reduction of hernial sac and contents, so that intestinal obstruction is still present. (05 Mar 2000) |
| reduction mammaplasty | Plastic surgery of the breast to reduce its size and (frequently) to improve its shape and position. (05 Mar 2000) |
| reduction nucleus | A nucleus that degenerates in the cell during the changes incident to fertilization. (05 Mar 2000) |
| reduction of chromosomes | The process during meiosis whereby one member of each homologous pair of chromosomes is distributed to a sperm or ovum; the diploid set of chromosomes (46 in humans) is thus reduced to the haploid set in each gamete; union of the sperm and ovum then restores the diploid or somatic number in the one-cell zygote. (05 Mar 2000) |
| reduction phase | The stage of nuclear changes in the sexual cells during which reduction of the chromosomes takes place; it embraces the cell generations of the spermatocytes and oocytes. Synonym: reduction phase. (05 Mar 2000) |
| reduction potential | The inherent tendency of a compound to act as an electron donor or an electron acceptor. Measured in volts. (09 Oct 1997) |
| risk reduction | Techniques used to reduce your chances of getting a certain cancer. For example: reducing your dietary fat may help prevent breast cancer. (09 Oct 1997) |
| closed reduction | The physical manipulation of a joint or bone externally (without making a surgical incision) to affect a joint relocation or more proper anatomic alignment of broken bone fragments. Closed reductions are often performed using intravenous analgesics, local anaesthetic nerve blocks or regional anaesthesia. (27 Sep 1997) |