| H fields | Three circumscript, myelin-rich regions of the subthalamus known as H fields (from Haubenfelder); 1) field H1, corresponding to the thalamic fasciculus, a horizontal fibre stratum at the junction of the subthalamus and the overlying thalamus, is composed of pallidothalamic and cerebellothalamic fibres (brachium conjunctivum) and is separated by the zona incerta from the more ventrally placed field H2; 2) field H2, formed by the lenticular fasciculus and arching over the dorsal border of the subthalamic nucleus, is composed largely of pallidothalamic fibres; 3) field H3 or prerubral field, is a large field of intermingling gray and white matter immediately rostral to the red nucleus, uniting fields H1 and H2 around the medial margin of the zona incerta; its gray matter forms the prerubral nucleus. See: lenticular loop. Synonym: campi foreli, tegmental fields of Forel. (05 Mar 2000) |
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| shear fields | <radiobiology> As used in plasma physics, this refers to magnetic fields having a rotational transform (or, alternatively, safety factor) that changes with radius (for example, in the stellarator concept, magnetic fields that increase in pitch with distance from the magnetic axis.) (09 Oct 1997) |
| tegmental fields of Forel | Three circumscript, myelin-rich regions of the subthalamus known as H fields (from Haubenfelder); 1) field H1, corresponding to the thalamic fasciculus, a horizontal fibre stratum at the junction of the subthalamus and the overlying thalamus, is composed of pallidothalamic and cerebellothalamic fibres (brachium conjunctivum) and is separated by the zona incerta from the more ventrally placed field H2; 2) field H2, formed by the lenticular fasciculus and arching over the dorsal border of the subthalamic nucleus, is composed largely of pallidothalamic fibres; 3) field H3 or prerubral field, is a large field of intermingling gray and white matter immediately rostral to the red nucleus, uniting fields H1 and H2 around the medial margin of the zona incerta; its gray matter forms the prerubral nucleus. See: lenticular loop. Synonym: campi foreli, tegmental fields of Forel. (05 Mar 2000) |
| electromagnetic fields | Fields representing the joint interplay of electric and magnetic forces. (12 Dec 1998) |
| fields of Forel | Three circumscript, myelin-rich regions of the subthalamus known as H fields (from Haubenfelder); 1) field H1, corresponding to the thalamic fasciculus, a horizontal fibre stratum at the junction of the subthalamus and the overlying thalamus, is composed of pallidothalamic and cerebellothalamic fibres (brachium conjunctivum) and is separated by the zona incerta from the more ventrally placed field H2; 2) field H2, formed by the lenticular fasciculus and arching over the dorsal border of the subthalamic nucleus, is composed largely of pallidothalamic fibres; 3) field H3 or prerubral field, is a large field of intermingling gray and white matter immediately rostral to the red nucleus, uniting fields H1 and H2 around the medial margin of the zona incerta; its gray matter forms the prerubral nucleus. See: lenticular loop. Synonym: campi foreli, tegmental fields of Forel. (05 Mar 2000) |
| alpha particles | Positively charged particles composed of two protons and two neutrons, i.e., helium nuclei, emitted during disintegration of very heavy isotopes; a beam of alpha particles or an alpha ray has very strong ionizing power, but weak penetrability. (12 Dec 1998) |
| chromatin particles | Fine bluish dots thought to represent remnants of the nucleus, occasionally seen in stained erythrocytes. (05 Mar 2000) |
| submitochondrial particles | The various filaments, granules, tubules or other inclusions within mitochondria. (12 Dec 1998) |
| electron transport particles | <cell biology> Fragments of mitochondria still capable of transporting electrons. One of the units occurring on the matrical surface of mitochondrial cristae; the head of the particle which measures about 9 nm, attaches to the membrane of the crista by a stalk 5 nm in length; the particle may be concerned with the electron transport system. Synonym: submitochondrial particles. (05 Mar 2000) |
| elementary particles | <radiobiology> at a nuclear-energy level: electron & positron - seem to be stable, proton - thought to be stable, life greater than 10^30 sec, neutron - decays in ?6 min unless its in a nucleus, which often extends its life. Other particles important for nuclear energy: Muon, neutrino (m, e, tau), photon, Muonic atoms, Pi-meson antiparticles (09 Oct 1997) |
| kappa particles | Inheritable cytoplasmic symbionts, once thought to be particle's mainly or exclusively of DNA, occurring in some strains of Paramecium; capable of producing a product lethal to other strains. (05 Mar 2000) |
| abstracting and indexing | Shortening or summarizing of documents; assigning of descriptors for referencing documents. (12 Dec 1998) |
| academies and institutes | Organizations representing specialised fields which are accepted as authoritative; may be non-governmental, university or an independent research organization, e.g., national academy of sciences, brookings institution, etc. (12 Dec 1998) |
| accounts payable and receivable | Short-term debt obligations and assets occurring in the regular course of operational transactions. (12 Dec 1998) |
| aged, 80 and over | A person 80 years of age and older. (12 Dec 1998) |