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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The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

fixation

[fik′sā·shən]
(psychology)
A rigid habit developed as a consequence of repeated reinforcement, or of frustration.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

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
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
The fixation stability task requires participants to stably fix their eyes on a fixed point on the screen, and to inhibit the possible pro-saccades and remain staring at the fixed point when interference factors appear.
We looked at two measures of fixation during this study: fixation count and fixation duration.
Furthermore, complications related to the pin head fixation device were related to the presence of a posterior fossa tumor, temporal application of the pins, prolonged surgery, presence of hydrocephalus, and age below 7 years.
In line with this contention, some studies found that COG fixations benefit task performance.
The right of reproduction is the right to authorize direct or indirect reproduction of the performance fixed in an audiovisual fixation in any manner or form.
As already described, processing deliberately leads to a higher number of fixations and longer fixation durations.
For posterior screw fixation, the patients were positioned supine on a radiolucent table and in hyperextension with handmade pillows placed vertical to the sacral fracture line (Figure 1(a)).
(2) Compared to the use of TG-based materials and PM-based materials, the use of AR-based materials that are designed using the CTML can lower learners' cognitive loads and foster deep information processing, which means that AR-based groups will have lower fixation counts and fixation times but higher levels of average fixation duration than TG- and PM-based groups.
Lateral mass screw fixation (LSF) with plates or rods has become the standard method for posterior cervical spine fixation and stability.2
Eye movements in the problem exploring stage of interactive problems--(a) eye fixations and saccades of a high-performing student, (b) eye fixations and saccades of a low-performing student.
That study reported difficulty in reduction and fixation of the VLF fragment with a VLP because of the anatomical structure and biomechanics in this region.