| balas ruby | <chemical> A variety of spinel ruby, of a pale rose red, or inclining to orange. See Spinel. Origin: OE. Bales, balais, F. Balais, LL. Balascus, fr. Ar. Balakhsh, so called from Badakhshan, Balashan, or Balaxiam, a place in the neighborhood of Samarcand, where this ruby is found. Source: Websters Dictionary (01 Mar 1998) |
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| ruby | Origin: F. Rubis (cf. Pr. Robi), LL. Rubinus, robinus, fr. L. Rubeus = red, reddish, akin to ruber. See Rouge, red. 1. <chemical> A precious stone of a carmine red colour, sometimes verging to violet, or intermediate between carmine and hyacinth red. It is a red crystallized variety of corundum. Besides the true or Oriental ruby above defined, there are the balas ruby, or ruby spinel, a red variety of spinel, and the rock ruby, a red variety of garnet. "Of rubies, sapphires, and pearles white." (Chaucer) 2. The colour of a ruby; carmine red; a red tint. "The natural ruby of your cheeks." (Shak) 3. That which has the colour of the ruby, as red wine. Hence, a red blain or carbuncle. 4. See Agate. 5. <ornithology> Any species of South American humming birds of the genus Clytolaema. The males have a ruby-coloured throat or breast. <chemistry> Ruby of arsenic, Ruby of sulphur, red silver. See Red. Source: Websters Dictionary (01 Mar 1998) |
| ruby spots | <tumour> A red papule due to weakening of the capillary wall, seen mostly in persons over 30 years of age. Synonym: cherry angioma, De Morgan's spots, ruby spots. (05 Mar 2000) |
| solid state laser | <radiobiology> A laser using a transparent substance (crystalline or glass) as the active medium, doped to provide the energy states necessary for lasing. The pumping mechanism is the radiation from a powerful light source, such as a flashlamp. The ruby, Nd-YAG, and Nd:glass lasers are solid-state lasers. (09 Oct 1997) |
| spectrometry, mass, matrix-assisted laser desorption-ionization | A mass spectrometric technique that is used for the analysis of large biomolecules. Analyte molecules are embedded in an excess matrix of small organic molecules that show a high resonant absorption at the laser wavelength used. The matrix absorbs the laser energy, thus inducing a soft disintegration of the sample-matrix mixture into free (gas phase) matrix and analyte molecules and molecular ions. In general, only molecular ions of the analyte molecules are produced, and almost no fragmentation occurs. This makes the method well suited for molecular weight determinations and mixture analysis. (12 Dec 1998) |
| dye laser | <radiobiology> A type of laser in which the active material (the material which emits the laser light) is a dye. These lasers are tunable when the dye has very large molecules (such as acridine red or esculin) and the laser action takes place between the first excited and ground electronic states, because each of these states contains a broad continuum band of vibrational-rotational levels. (09 Oct 1997) |
| yag laser surgery | <ophthalmology, procedure, surgery> The use of laser light to punch a hole in the iris to relieve intraocular pressure within the eye (for example glaucoma). This surgery is painless and requires no anaesthesia. (27 Sep 1997) |
| keratectomy, photorefractive, excimer laser | A type of refractive surgery of the cornea to correct myopia and astigmatism, using an excimer laser. An excimer laser is a laser containing a noble gas, such as helium or neon, which is based on a transition between an excited state in which a metastable bond exists between two gas atoms and a rapidly dissociating ground state. The extremely precise laser light reshapes the surface of the cornea without making an incision. This procedure can reduce much higher degrees of myopia than radial keratotomy (keratotomy, radial), although it generally takes longer for vision to clear. (12 Dec 1998) |
| laser | A medical instrument that produces a powerful beam of light and can produce intense heat when focused at close range. Lasers are often used in surgery to vaporize damaged cell tissue. (16 Dec 1997) |
| laser angioplasty | <cardiology, procedure> A technique utilizing a laser coupled to a catheter which is used in the dilatation of occluded blood vessels. This includes laser thermal angioplasty where the laser energy heats up a metal tip, and direct laser angioplasty where the laser energy directly ablates the occlusion. One form of the latter approach uses an excimer laser which creates microscopically precise cuts without thermal injury. When laser angioplasty is performed in combination with balloon angioplasty it is called laser-assisted balloon angioplasty (angioplasty, balloon, laser-assisted). (05 Mar 2000) |
| laser-assisted balloon angioplasty | <cardiology, procedure> Techniques using laser energy in combination with a balloon catheter to perform angioplasty. These procedures can take several forms including: 1. Laser fibre delivering the energy while the inflated balloon centres the fibre and occludes the blood flow. 2. Balloon angioplasty immediately following laser angioplasty. 3. Laser energy transmitted through angioplasty balloons that contain an internal fibre. (05 Mar 2000) |
| laser coagulation | The coagulation of tissues using lasers. These lasers produce light in the visible green wavelength that is selectively absorbed by haemoglobin, and thus it is possible to seal bleeding blood vessels. (12 Dec 1998) |
| laser-doppler flowmetry | A method of non-invasive, continuous measurement of microcirculation. The technique is based on the values of the doppler effect of low-power laser light scattered randomly by static structures and moving tissue particulates. (12 Dec 1998) |
| laser fusion | <radiobiology> Form of inertial confinement fusion where laser beams are used to compress and heat the fuel pellet. (09 Oct 1997) |
| laser interferometer | <radiobiology> An interferometer which uses a laser as a light source. Because of the monochromatic nature and high brightness of laser light, laser interferometers can operate with much longer beam paths and path differences than conventional interferometers. (09 Oct 1997) |