optical activity

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1. the quality or process of exerting energy or of accomplishing an effect.
2. a thermodynamic quantity that represents the effective concentration of a solute in a non-ideal solution. Symbol a.
3. the number of disintegrations per unit of a radioactive material. Symbol A.
4. the presence of recordable electrical energy in a nerve or muscle.
a's of daily living (ADL) activities that are necessary for daily care of oneself and independent community living. It includes using the toilet and grooming, dressing, and feeding oneself; independent community living includes driving, shopping, homemaking, care of family, work activities, and so on. See also self care, self care deficit, and self care assistance.(See accompanying table.)
deficient diversional activity a nursing diagnosis approved by the North American Nursing Diagnosis Association, defined as the experiencing by an individual of decreased stimulation from, interest in, or engagement in recreational or leisure activities. Formerly called diversional activity deficit. Possible causes include prolonged hospitalization or immobility at home, frequent and lengthy treatments such as renal dialysis, and a monotonous, nonstimulating environment. The patient usually gives subjective evidence that this condition exists by verbalizing a feeling of boredom or stating a desire for something to do or gives objective evidence by acting depressed or restless.

Nursing interventions that could be appropriate for diversional activity deficit include interviewing the patient to assess the current situation and to assist in developing plans for activities that provide interest and stimulation. These activities could include music, games, reading, handwork, or any other pastimes enjoyed by the patient. Patients may need assistance in identifying available resources and motivation to take advantage of the activities they provide.
enzyme activity the catalytic effect exerted by an enzyme, expressed as units per milligram of enzyme (specific activity) or molecules of substrate transformed per minute per molecule of enzyme (molecular activity).
malignant ventricular ectopic activity ventricular fibrillation or ventricular tachycardia with syncope, heart failure, myocardial ischemia, or hypotension.
optical activity the ability of a chemical compound to rotate the plane of polarization of plane-polarized light.
physical activity bodily movements, such as those accompanying activities of daily living.
pulseless electrical activity (PEA) continued electrical rhythmicity of the heart in the absence of effective mechanical function; it may be due to uncoupling of ventricular muscle contraction from electrical activity or may be secondary to cardiac damage with respiratory failure and cessation of cardiac venous return. Called also electromechanical dissociation.
purposeful activity in occupational therapy, tasks or experiences in which the individual actively participates that require and elicit coordination between the sensory, motor, cognitive, and psychological systems. Each person has a unique set of purposeful activities, influenced by his or her life roles, and, when doing one of them, directs attention to the task itself rather than to the internal processes involved. Activities may yield immediate results or may require sustained effort and repetition, and they may either represent new responses or be part of complex, longstanding patterns of behavior.
sustained rhythmic activity the continuous generation of action potentials within the heart in the absence of artificial or external stimulation.
triggered activity activity in which nondriven action potentials arise from afterpotentials that were caused by the previous action potential.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

optical activity

The property of some substances in solution of causing of a ribbon-like beam of polarized light projected through the solution to twist through a small angle. Some substances cause rotation of the beam to the left (levorotatory), some to the right (dextrorotatory). Some optically active drugs are more potent in one form than in the other; a few are almost inert in one rotatory form.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
Hess, "Chiral metamaterials: enhancement and control of optical activity and circular dichroism," Nano Convergence, vol.
The PTrMA with DP = 50 is conformationally very stable even at rather high temperatures in solution and did not show any change in optical activity when heated at 60[degrees]C in THF, and the poly(D2PyMA) with DP = 80 was also conformationally stable mainly due to association of the polymer chains.
The stronger CD effect, giant optical activity and multiple negative refractive index bands could be obtained by numerical simulations based on the frequency domain finite element method.
Target compounds have properties ranging from highly selective separations agents, porous solids for gas storage, compounds with second order non-linear optical activity, and the formation of highly ordered proton conducting solids.
The promise of photonic BC systems underscores the importance of characterizing their local optical properties, since the optical activity of single microphase domains and defect structures may dictate device function.
The work of van't Hoff, ten years before, had shown the importance of the three-dimensional arrangement of atoms in a molecule and the way this could be responsible for optical activity (see 1874).
A polarimeter is a chemical instrument used to determine the optical activity of a substance.
Summary: A polarimeter is a chemical instrument used to determine the optical activity of a substance.
Conventional polarization converters were usually designed by using the birefringence effect and optical activity of natural materials, which usually suffer from bulky volumes, high losses, and narrow bandwidth in practical applications [2,3].
developed an improved piezoelectric polymer based on helical chiral polymers with optical activity and weight-average molecular weights from 50,000 to 1,000,000.