activity

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activity

1. the number of disintegrations of a radioactive substance in a given unit of time, usually expressed in curies or disintegrations per second
2. 
a. the capacity of a substance to undergo chemical change
b. the effective concentration of a substance in a chemical system. The absolute activity of a substance B, λB, is defined as exp (μBRT) where μB is the chemical potential
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

activity

[‚ak′tiv·əd·ē]
(computer science)
The use or modification of information contained in a file.
(nuclear physics)
The intensity of a radioactive source. Also known as radioactivity.
(physical chemistry)
A thermodynamic function that correlates changes in the chemical potential with changes in experimentally measurable quantities, such as concentrations or partial pressures, through relations formally equivalent to those for ideal systems.
(systems engineering)
The representation in a PERT or critical-path-method network of a task that takes up both time and resources and whose performance is necessary for the system to move from one event to the next.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

activity

In CPM terminology, a task or item of work that must be performed in order to complete a project.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Using the washed film strips, the effect of enzyme concentration on immobilized enzyme activity was tested to detect the immobilized enzyme leakage.
In order to determine the nitrate reductase enzyme activity, leaves were collected from four replicates per treatment, out of the last trifoliate developed in the vegetative (V3) and reproductive (R5) stages.
Units/mL enzyme = micromole tyrosine equivalents released x total volume of assay) / (Volume of enzyme used x time of assay x volume used in colorimetric determination Optimization of temperature, pH and salinity for the enzyme activity
In this study, serum ALP enzyme activity of broilers was decreased by dietary natamycin supplementation at a dose level of 50 mg/kg as compared with the CON group at 21d in broilers.
Lafase HE Grand Cru also contains high levels of a specific enzyme activity, Rhamnogalacturonase-II (RGII-ase), which selectively releases the pectin structure RGII, which aids in stabilizing color and structure in red wines.
It was also studied earlier that the metal ions such as; [Ca.sup.+2], [Mg.sup.+2] and [Mn.sup.+2] increase the enzyme stabilization which results in the increase in enzyme activity and thermal stability of alkaline proteases at higher temperature (Kumar, 2002).
The enzyme activity assay results of final cultivation tubes showed that 8 isolates (1, 2, 3, 6, 12, 16, 17, and 18) had remarkable activity (Figure 2).
Glycocerebrosidase enzyme activity showed a positive correlation with the total number of leukocytes and the number of neutrophils (Figure 1a).
At present, drip irrigation with plastic is increasingly being used in greenhouses, but research about the effect of drip irrigation with plastic mulch on soil enzyme activity has mostly focused on cultivated fields and saline-alkali land (Bozkurt et al.
These results suggest the significance of soil temperature in controlling in situ enzyme activities in the paddy soil and also that the stoichiometry of extracellular enzyme activity associated with C, N, and P acquisition reflects the soil nutrient availability.
However, the concentration of D-xylose was higher (from 2.0 to 2.5%), and the enzyme activity was reduced from 0.255 to 0.233 U/mg biomass.