fixation

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fixation:

see psychoanalysispsychoanalysis,
name given by Sigmund Freud to a system of interpretation and therapeutic treatment of psychological disorders. Psychoanalysis began after Freud studied (1885–86) with the French neurologist J. M.
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.

Fixation

 

a method of preserving the structure of animal and plant cells and tissues through treatment with chemical and physical agents. Fixation is used to obtain medicinal preparations.

Physical techniques include drying and freezing at low temperatures in a vacuum (lyophilization). Specimens may be treated chemically with such reagents as formaldehyde, alcohol, acetone, and osmium tetroxide. Many reagents are used in combination with other substances, such as potassium bichromate, mercuric chloride, and picric acid; such fixatives are usually named after the researchers who proposed them, for example, Zenker’s and Maximow’s fixatives and Flemming’s, Carnoy’s, and Bouin’s solutions. The choice of technique depends on the properties and size of the specimen and the purpose of the study. For example, alcohol fixation is adequate to preserve nucleic acids, but enzyme activity is completely preserved only after lyophilization. Fixation in aldehydes is recommended for electron microscopy. Double fixation is used for better preservation of tissue, that is, primary fixation with an aldehyde fixative and a second fixation with osmium tetroxide.

REFERENCES

Roskin, G. I., and L. B. Levinson. Mikroskopicheskaia tekhnika, 3rd ed. Moscow, 1957.
Rukovodstvo po tsitologii, vol. 1. Moscow-Leningrad, 1965.

M. E. ASPIZ

fixation

[fik′sā·shən]
(psychology)
A rigid habit developed as a consequence of repeated reinforcement, or of frustration.

fixation

1. Psychol
a. the act of fixating
b. (in psychoanalytical schools) a strong attachment of a person to another person or an object in early life
2. Chem
a. the conversion of nitrogen in the air into a compound, esp a fertilizer
b. the conversion of a free element into one of its compounds
3. the reduction of a substance from a volatile or fluid form to a nonvolatile or solid form
References in periodicals archive ?
Regarding POA, significantly shorter fixation durations were found for the high-performing group than for the low-performing group and significantly fewer visit counts for the high-performing group than for the low-performing group.
Regarding POA, significantly longer fixation durations were found for the high-performing group than for the low-performing group and significantly fewer visit counts for the high-performing group than for the low-performing group.
Implant fracture and migration was noted at checkups in 29 cases (46%) in the group with short fixation and in 11 cases (30.
4%) out of 22 patients from the group with short fixation and 7 out of 17 patients from the group with long fixation (41.
The results of independent sample t-test indicated that compared with controls, patients with depressive disorder showed more fixation times (7.
According to the results of correlation analyses for eye movement indices on the fixation stability task and the saccade task, HAMD scores and HAMA scores, the pro-saccade amplitude was negatively correlated with HAMA scores (r=-0.
Carpenter, 1976: Eye fixations and cognitive processes.
The initial high number of reflectivity AOI fixation counts in period 1 resulted from using these data to assess storm intensity.
Patients return to the operating room for a second procedure for definitive reduction and fixation of the articular surface when soft tissue swelling has subsided usually within 10-14 days.
The risk of the depressed fracture from pin fixation has to be balanced by the benefits of rigid fixation, and the risks of using other head rests, especially for prolonged operations, where there is a risk of skin damage by pressure from a headrest, such as a horseshoe headrest.
There is no specific literature available for the outcome of fixation of transverse metacarpal and phalangeal fractures.