Inversion

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inversion

1. Chem
a. the conversion of a dextrorotatory solution of sucrose into a laevorotatory solution of glucose and fructose by hydrolysis
b. any similar reaction in which the optical properties of the reactants are opposite to those of the products
2. Music
a. the process or result of transposing the notes of a chord (esp a triad) such that the root, originally in the bass, is placed in an upper part. When the bass note is the third of the triad, the resulting chord is the first inversion; when it is the fifth, the resulting chord is the second inversion
b. (in counterpoint) the modification of a melody or part in which all ascending intervals are replaced by corresponding descending intervals and vice versa
c. the modification of an interval in which the higher note becomes the lower or the lower one the higher
3. Pathol abnormal positioning of an organ or part, as in being upside down or turned inside out
4. Psychiatry
a. the adoption of the role or characteristics of the opposite sex
b. another word for homosexuality
5. Meteorol an abnormal condition in which the layer of air next to the earth's surface is cooler than an overlying layer
6. Computing an operation by which each digit of a binary number is changed to the alternative digit, as 10110 to 01001
7. Genetics a type of chromosomal mutation in which a section of a chromosome, and hence the order of its genes, is reversed
8. Logic the process of deriving the inverse of a categorial proposition
9. Maths a transformation that takes a point P to a point Pʹ such that OP?OPʹ = a2, where a is a constant and P and Pʹ lie on a straight line through a fixed point O and on the same side of it

Inversion

 

in chemistry. (1) A change in the conformation of a cyclic molecule as a result of which the orientation of the substituent with respect to the ring changes. For example, methylcyclohexane exists in the form of an equilibrium mixture of two conformations, form II predominating (see Figure 1).

The frequency of inversion depends on the nature of the substituents and on temperature.

(2) The conversion of the configuration of a molecule containing a trivalent “pyramidal” atom (for example, nitrogen or arsenic) into the mirror image. Thus, for a molecule with a trivalent atom, forms I and II are the optical antipodes:

where a, b, and c are different atoms or groups of atoms. The energy barrier for inversion is usually low and depends on the temperature and the nature of a, b, and c. For the carbon atom (a “tetrahedral” atom), the term “configuration reversal” is usually used.

(3) The inversion of sugar is the hydrolysis of a saccharose (such as beet sugar) accompanied by a change in the direction of rotation of the plane of a polarized beam of light by a sugar solution.

B. L. DIATKIN


Inversion

 

(1) In geometry, inversion with respect to a given circle of radius R with a center O is a transformation (see Figure 1) in which a point P is converted to a point P ′ (in Figure 1 the points Pand P ′ are given with numerical subscripts), which lies on a radial line OP at a distance OP ′ = R2/OP from the center O; the number R2 is called the inversion factor. Upon inversion, straight lines and circles become straight lines and circles, and circles, for example, may become straight lines and vice versa. Inversion in space with reference to a sphere is defined similarly. The transformation of an inversion has numerous applications in geometry (the interpretation of Lobachevskii’s geometry, the theory of geometric constructions) and in the theory of mechanisms—so-called inversors.

Figure 1

(2) In combinatorial analysis, inversion is the disruption of the normal sequence of two elements in a permutation regardless of whether these two terms stand together or are separated from each other by some other elements, for example, in the permutation eacbd the terms a and e, c and e, b and e, d and e, and b and c form an inversion if abcde is considered to be the normal order.


Inversion

 

a change in the usual word order in a sentence. Inversion is generally used to accentuate the rearranged element in the sentence and to give the entire sentence special meaning. In languages with fixed word order, inversion has a grammatical function—for example, to form interrogative sentences in Russian, English, and French. It is one of the aspects of the actual division of a sentence—for example, Russian Videl ia otsa (“Saw I Father”) and German Den Sohn liebt die Mutter (literally, “The son [accusative] loves the mother [nominative],” that is, “The mother loves the son”).

Frequently, inverted forms that are not accepted in everyday speech are used in poetry. For example, A. S. Pushkin: Minutnykh zhizni vpechatlenii / Ne sokhranit dusha moia (roughly, “The fleeting impressions of life/ My soul does not retain”) and Pod vecher, osen ‘iu nenastnoi, / V dalekikh deva shla mestakh (roughly, “Toward evening, in rainy autumn, / In far-off places a maiden walked”).

inversion

[in′vər·zhən]
(chemistry)
Change of a compound into an isomeric form.
(communications)
The process of scrambling speech for secrecy by beating the voice signal with a fixed, higher audio frequency and using only the difference frequencies.
(crystallography)
A change from one crystal polymorph to another. Also known as transformation.
(electricity)
The solution of certain problems in electrostatics through the use of the transformation in Kelvin's inversion theorem.
(genetics)
A type of chromosomal rearrangement in which two breaks take place in a chromosome and the orientation of the fragment between breaks rotates 180° before rejoining.
(geology)
Development of inverted relief through which anticlines are transformed into valleys and synclines are changed into mountains.
The occupancy by a lava flow of a ravine or valley that occurred in the side of a volcano.
A diagenetic process in which unstable minerals are converted to a more stable form without a change in chemical composition.
(mathematics)
Given a point O lying in a plane or in space, a mapping of the plane or of space, excluding the point O, into itself in which every point is mapped into its inverse point with respect to a circle or sphere centered at O.
The interchange of two adjacent members of a sequence.
(mechanical engineering)
The conversion of basic four-bar linkages to special motion linkages, such as parallelogram linkage, slider-crank mechanism, and slow-motion mechanism by successively holding fast, as ground link, members of a specific linkage (as drag link).
(medicine)
The act or process of turning inward or upside down.
(meteorology)
A departure from the usual decrease or increase with altitude of the value of an atmospheric property, most commonly temperature.
(optics)
The formation of an inverted image by an optical system.
(physics)
The simultaneous reflection of all three directions in space, so that each coordinate is replaced by the negative of itself. Also known as space inversion.
(solid-state physics)
The production of a layer at the surface of a semiconductor which is of opposite type from that of the bulk of the semiconductor, usually as the result of an applied electric field.
(thermodynamics)
A reversal of the usual direction of a variation or process, such as the change in sign of the expansion coefficient of water at 4°C, or a change in sign in the Joule-Thomson coefficient at a certain temperature.

inversion

inversionclick for a larger image
In meteorology, a departure from the usual decrease or increase with altitude of the value of an atmospheric property. Also, the layer through which this departure occurs, called the inversion layer, or the lowest altitude at which the departure is found (i.e., the base of the inversion). This term almost always means a temperature inversion and an increase in temperature with height. It is one of the causes for the formation of smog. The presence of an inversion creates a very stable atmosphere; when it occurs at the surface it leads to very little mixing and a trapping of pollutants in the lower atmosphere.
References in periodicals archive ?
Indeed, careful examination of the resting ECG (Figure 2) reveals T-wave inversion (grey arrows) without ST-segment depression but with early repolarisation in Leads V2-V4 (black arrows).
If it had been requested, pre-existing T-wave inversion in the inferolateral leads would have been observed and resulted in further investigation prior to general anaesthesia.
As the objective of this study was to determine LAD stenosis in relation to T-wave inversion, lesions of LAD recorded as proximal, mid, distal, osteal, proximal-distal, left main stenosis were accounted for as separate variables.
Out of the total of 100 patients included in the study, 26 (26%) patients showed biphasic T-wave inversion in leads v2- v3 (Group 1), whereas 25 (25%) patients showed these changes in leads v2-v4 (Group 2) (Figure).
Left-sided pneumothoraces generally cause a rightward QRS shift, loss of precordial R-wave voltage, and precordial T-wave inversion.
His post-cardioversion ECG showed persistent T-wave inversions in leads [V.
These included the documentation of sustained VT of the morphology described in Table 1 (arrhythmia criteria), the presence of epsilon waves (depolarization criteria) and T-wave inversions in [V.
With all the classic risk factors--hyperlipidemia, hypertension, cigarette smoking, and electrocardiogram T-wave inversions found in ischemia--it was reportedly obvious he was experiencing an acute coronary syndrome.
Electrocardiography showed dynamic T-wave inversions in the anterolateral precordial leads [Figure 1].
On admission, the electrocardiogram showed that T-wave inversions were visible in most leads, QRS duration was prolonged with 120 ms, and the terminal depolarizations might be interpreted as epsilon waves in leads V1–V5 [Figure 1]a arrows].
A repeat electrocardiogram the morning after admission showed that the inverted U waves had virtually disappeared but were replaced by striking terminal T-wave inversions in the anterolateral leads (Figure 2).