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

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.

activity

In CPM terminology, a task or item of work that must be performed in order to complete a project.
References in periodicals archive ?
The data presented here are semiquantifiable, in that the data are accurate for relative comparisons of enzyme activity among samples, and should not be taken to indicate an absolute quantity.
Despite the fact that numerous studies have been conducted to elucidate the effects of global climate change on grassland plants and communities, knowledge regarding the response of soil enzyme activity to climate change remains limited.
If you want to know more about the enzyme activity assay services provided by Creative Biomart, you can visit http://www.
These results suggest that root activity and root size (root surface area) are more important than root biomass in affecting enzyme activity.
The relative activity was calculated as the relative enzyme activity compared to the maximum value observed across the range of temperatures.
In general, increases in enzyme activity are associated with increased biological activity in the soil, which is considered to be an important indicator of soil quality (DICK, 1992, 1994).
The saccharolytic enzyme activity in the supernatants was determined by hydrolyzing 4 mg of starch at 55 C for 10 minutes.
The enzyme activity of IDUA was low in sodium citrate and sodium citrate-phosphate buffers at all pH values, so sodium formate was chosen as the preferred buffer salt.
The level of enzyme activity was determined by measuring the difference in optical density.
Biological changes in extracellular matrix components observed in photoaging are induced by Reactive Oxygen Species, which stimulate MMP enzyme activity resulting in a decrease of the extracellular matrix.
It decreased lipid peroxidation in patients with type II diabetes and systolic blood pressure and serum angiotensin converting enzyme activity in hypertensive patients.
They observed that the people who had the highest enzyme activity within the MAO-A polymorphism had a significantly lower placebo response than those with other genotypes.