| centre of rotation | A point or line around which all other points in a body move. See: axis. (05 Mar 2000) |
|---|---|
| rotation | <dentistry> A movement in which the tooth turned along the long axis of the tooth. (08 Jan 1998) |
| rotation flap | A pedicle flap that is rotated from the donor site to an adjacent recipient area, usually as a direct flap. (05 Mar 2000) |
| rotation therapy | Teletherapy in which a desirable radiation dose distribution is achieved by rotating the patient or machine about an axis passing through the centre of the tumour. (05 Mar 2000) |
| short rotation energy plantation | Plantings established and managed under short-rotation intensive culture practices. (05 Dec 1998) |
| short rotation intensive culture | Intensive management and harvesting at 2 to 10 year intervals of cycles of specially selected fast- growing hardwood species for the purpose of producing wood as an energy feedstock. (05 Dec 1998) |
| intestinal rotation | See: malrotation. Molecular rotation, one hundredth of the product of the specific rotation of an optically active compound and its molecular weight. Optical rotation, the change in the plane of polarization of polarised light of a given wavelength upon passing through optically active substances; measured in terms of specific rotation by polarimetry, an important tool in chemical structural work, especially on carbohydrates. Specific optical rotation ([a]), the arc through which the plane of polarised light is rotated by 1 gram of a substance per milliliter of water when the length of the light path through the solution is 1 decimeter, typically using light corresponding to the D line of sodium. (05 Mar 2000) |
| axis, optical | <microscopy> Usually refers to the axis on which several principal lens axes may lie. It also refers to the axis of the eye which extends through the centre of the eye lens. The line formed by the coinciding principal axes of a series of optical elements comprising an optical system. It is the line passing through the centres of curvature of the optical surfaces. (05 Aug 1998) |
| specific optical dispersion | <microscopy> The difference between the refractive indices of light of two different wavelengths, both indices measured at the same temperature, the difference being divided by the specific gravity also measured in the same medium at the test temperature. For convenience, the specific dispersion value is multiplied by ten. (05 Aug 1998) |
| optical | 1. Of or pertaining to vision or sight. "The moon, whose orb Through optic glass the Tuscan artist views." (Milton) 2. Of or pertaining to the eye; ocular; as, the optic nerves (the first pair of cranial nerves) which are distributed to the retina. 3. Relating to the science of optics; as, optical works. <optics> Optic angle, a graduated circle used for the measurement of angles in optical experiments. Optical square, a surveyor's instrument with reflectors for laying off right angles. Origin: F. Optique, Gr.; akin to sight, I have seen, I shall see, and to the two eyes, face, L. Oculus eye. See Ocular, Eye, and cf. Canopy, Ophthalmia. Source: Websters Dictionary (01 Mar 1998) |
| optical aberration | Failure of rays from a point source to form a perfect image after traversing an optical system. (05 Mar 2000) |
| optical activity | The ability of a material to rotate the plane of polarized light. (09 Oct 1997) |
| optical antipode | <chemistry> A pair of chiral isomers (stereoisomers) that are direct, nonsuperimposable mirror images of each other. (09 Jan 1998) |
| optical axis | <physics> The line passing through both the centres of curvature of the optical surfaces of a lens, the optical centreline for all the centres of a lens system. (09 Oct 1997) |
| optical density | 1. <chemistry, investigation> Absorbance is defined as a logarithmic function of the percent transmission of a wavelength of light through a liquid. 2. <microbiology> This can be used as a measure of the amount of light absorbed by a suspension of bacterial cells or a solution of an organic molecule, it is measured by a colourimeter or spectrophotometer. Absorbance values are used to plot the growth of bacteria in suspension cultures and to gauge the purity and concentration of molecules (such as proteins) in solution. See: absorption. (15 Jan 1998) |