| ash | <radiobiology> Fusion reaction products trapped in a plasma. Ash is bad because (a) it generally radiates more strongly than the fuel ions, and thus reduces energy confinement, and (b) it creates additional plasma pressure and/or reduces pressure available for fuel ions. Controlling ash is a major area of fusion research. Ideally one would be able to extract the ash ions after diverting an appropriate fraction of their energy to heating the fuel ions, and then convert the remaining ash energy to electricity. Current research involves using RF waves to transfer energy from ash ions to fuel ions, and to push the ash into the scrape-off layer, where it can be collected via divertors. (09 Oct 1997) |
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| ash wednesday | The first day of Lent; so called from a custom in the Roman Catholic church of putting ashes, on that day, upon the foreheads of penitents. Source: Websters Dictionary (01 Mar 1998) |
| ash-fire | A low fire used in chemical operations. Source: Websters Dictionary (01 Mar 1998) |
| Ashby | Winifred, 20th century haematologist. See: Ashby method. (05 Mar 2000) |
| Ashby method | A differential agglutination method for estimating erythrocyte life span; compatible blood possessing a group factor that the recipient lacks is transferred to the recipient; after the transfusion, sera with potent agglutinins for the recipient's red cells are added to samples of the recipient's blood, and the unagglutinated red cells are counted; using this technique the red cell life span in normal persons is found to be 110 to 120 days. (05 Mar 2000) |
| ashen | Of or pertaining to the ash tree. See: Ash, the tree. Source: Websters Dictionary (01 Mar 1998) |
| ashen tuber | Layer of gray matter in the hypothalamus that also forms part of the floor of the third ventricle. (12 Dec 1998) |
| ashen tubercle | A longitudinal prominence on the dorsolateral surface of the medulla oblongata along the lateral border of the tuberculum cuneatum; it is the surface profile of the spinal tract of trigeminal nerve, continuous caudally with the dorsolateral fasciculus (Lissauer's tract). Synonym: ashen tubercle, gray tubercle, Rolando's tubercle. (05 Mar 2000) |
| ashen wing | A prominence in the floor of the inferior fovea of the fourth ventricle that overlies the dorsal motor nucleus of the vagus. Synonym: trigonum nervi vagi, ala cinerea, ashen wing, gray wing, trigone of vagus nerve, va'gi eminentia. (05 Mar 2000) |
| Asherman | Joseph G., Czechoslovakian gynecologist, *1889. See: Asherman's syndrome. (05 Mar 2000) |
| asherman disease | <radiology> Uterine synechiae, linear, lucent defects in uterus on HSG, usually secondary to endometrial trauma (D&C, etc.) (12 Dec 1998) |
| Asherman's syndrome | <syndrome> Synechiae within the endometrial cavity, often causing amenorrhoea and infertility. (05 Mar 2000) |
| ashes | 1. The earthy or mineral particles of combustible substances remaining after combustion, as of wood or coal. 2. Specifically: The remains of the human body when burnt, or when "returned to dust" by natural decay. "Their martyred blood and ashes sow." (Milton) "The coffins were broken open. The ashes were scattered to the winds." (Macaulay) 3. The colour of ashes; deathlike paleness. "The lip of ashes, and the cheek of flame." (Byron) In dust and ashes, In sackcloth and ashes, with humble expression of grief or repentance; from the method of mourning in Eastern lands. Volcanic ashes, or Volcanic ash, the loose, earthy matter, or small fragments of stone or lava, ejected by volcanoes. Origin: OE. Asche, aske, AS. Asce, aesce, axe; akin to OHG. Asca, G. Asche, D. Asch, Icel. & Sw. Aska, Dan. Aske, Goth. Azgo. Source: Websters Dictionary (01 Mar 1998) |
| Ashman | R., 20th century U.S. Physiologist. See: Ashman's phenomenon. (05 Mar 2000) |
| Ashman's phenomenon | Aberrant ventricular conduction of a beat ending a short cycle that is preceded by a longer cycle most commonly during atrial fibrillation. (05 Mar 2000) |
| acid-ash diet | A diet consisting mainly of fruits, vegetables, and milk (with minimal amounts of meat, fish, eggs, cheese, and cereals), which, when catabolised, leave an alkaline residue to be excreted in the urine. Synonym: acid-ash diet, basic diet. (05 Mar 2000) |
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| alkaline-ash diet | A diet consisting mainly of fruits, vegetables, and milk (with minimal amounts of meat, fish, eggs, cheese, and cereals), which, when catabolised, leave an alkaline residue to be excreted in the urine. Synonym: acid-ash diet, basic diet. (05 Mar 2000) |
| bone ash | Ca3(PO4)2;used as an antacid. Synonym: bone ash, bone phosphate, tertiary calcium phosphate, tricalcium phosphate, whitlockite. (05 Mar 2000) |
| bottom ash | Noncombustable ash that is left after solid fuel has been burned. (05 Dec 1998) |
| pearl-ash | <chemistry> A white amorphous or granular substance which consists principally of potassium carbonate, and has a strong alkaline reaction. The hydroxide of potassium hydrate, a hard white brittle substance, KOH, having strong caustic and alkaline properties; hence The impure potassium carbonate obtained by leaching wood ashes, and evaporating the lye, or as a white crystalline pearl-ash. It has previously been an important source of potassium compounds, and previously used in making soap, glass, etc. Synonym: caustic potash. Source: Websters Dictionary (01 Mar 1998) |
| fly ash | Small ash particles carried in suspension in combustion products. (05 Dec 1998) |