relaxation time


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re·lax·a·tion time (τ),

the time required for the substrate in an enzymatic or chemical reaction to fall to 1/e of its initial value.

relaxation time

in magnetic resonance imaging, the characteristic time it takes for a sample of atoms, whose nuclei have first been aligned along a static magnetic field and then excited to a higher-energy state by a radiofrequency (rf) signal, to return to a lower-energy equilibrium state. Two time parameters are used to describe the return, or relaxation, to the equilibrium state once the rf signal is turned off: T1 describes the relaxation of the system of spins into a condition of thermal equilibrium with its surroundings. T2 describes the relaxation of the energy that is traded within the system itself. Maps of the values of T1 or T2 as a function of position in the cross-sectional view constitute magnetic resonance images. Also called transverse relaxation time.

relaxation time

An MRI term for the post-excitation return of spins to their equilibrium distribution, in which there is no transverse magnetisation and the longitudinal magnetisation is at its maximum value and oriented in the direction of the static magnetic field. Transverse magnetisation decays toward zero after excitation at a characteristic time constant T2; longitudinal magnetisation returns toward equilibrium with a characteristic time constant T1.

re·lax·a·tion time

(τ) (rē'lak-sā'shŭn tīm)
The time required for the substrate in an enzymatic or chemical reaction to fall to 1/e of its initial value.
References in periodicals archive ?
It reduces the ionic mobility ([mu]) and increases the relaxation time.
Processing of MR images weighted by relaxation time T2 to increase their contrast resolution.
The parameter [alpha], was determined from the angle subtended by the radius of the circle with the Z-axis passing through the origin of Z'-axis is listed in table 3 the value of a between 0 and 1, describes the broad distribution of relaxation times in system .
The distribution of relaxation time shows the similar behavior.
Compared with the creamed phase, the weight of the longest relaxation time is enhanced and all time constants are increased.
The phase difference [theta] is directly and uniquely determined by the relaxation time of the system r and the oscillation frequency f; see Figure 3.
The parafangos show relaxation times higher than peloids.
They used magnetic resonance imaging (MRI)-based T2 relaxation times to track the evolution of early degenerative cartilage changes in the knee.
In fact, the higher the particle concentration, the greater the volume of surface-associated liquid and, hence, the larger the relaxation time shift in comparison with the liquid without particles.
For example, the linear-superposition requirement is not satisfied if the relaxation time in Eq.
The aim of this article is to find which analytical equation can be used to find relaxation time if we know server load and self-similarity degree of input traffic.