Transient changes, following

Irradiation of PFe02 in solutions by short, very intense, laser pulses produces transients such as 3 and 4. Absorbance changes following the production of 3 and 4 are ascribed to their decay and rate parameters can be estimated as shown in the Scheme. Note the units in (2.20) which are occasionally used for large rate constants. The mechanism shown is certainly a simplified one. 

The transient change in the transmembrane potential upon excitation. An action potential cycle consists of a transient depolarization of the cell membrane of an excitable cell (such as a neuron) as a result of increased permeability of ions across the membrane, followed by repolarization, hyperpolarization, and finally a return to the resting potential. This cycle typically lasts 1-2 milliseconds and travels along the axon from the cell body (or, axon hillock) to the axonal terminus at a rate of 1-100 meters per second. See Membrane Potential... 

Although the role of lipid composition in membrane function is not entirely understood, changes in composition can produce dramatic effects. Researchers have isolated fruit flies with mutations in the gene that encodes ethanolamine kinase (analogous to choline kinase Fig. 21-28). Lack of this enzyme eliminates one pathway for phosphatidylethanolamine synthesis, thereby reducing the amount of this lipid in cellular membranes. Flies with this mutation—those with the genotype easily shocked—exhibit transient paralysis following electrical stimulation or mechanical shock that would not affect wild-type flies. 

Hypericum 200 produced a decrease in firing rate in case of 5 neurons and the effect lasted from 1.5 - 14 min with a latency of 1 sec to 2 min. In two neurons there was a transient potentiation followed by inhibition. In one neuron there was an increase in firing rate within 2 min and the effect lasted for 11 min. Arsenic 30 produced a marked increase in firing rate within 1 sec and the effect lasted for 20 sec. In all the cases the control did not show any marked change in the firing rate (Sukul et al., 1991). 

The term pulse has different meanings, but in signal processing it refers to a rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value (see Fig. 1.26a) [68]. 

This electro-optical effect, commonly observed as transient changes in optical birefringence of a solution following application, removal, or reversal of a biasing electric field E(t), has been used extensively as a probe of dynamics of blopolymer solutions, notably by O Konski, and is a valuable tool because it gives information different in form, but related to, results from conventional dielectric relaxation measurements. The state of the subject to 1975 has been comprehensively presented in two review volumes edited by O Konski (25). The discussion here is confined to an outline of a response theory treatment, to be published in more detail elsewhere, of the quadratic effect. The results are more general than earlier ones obtained from rotational diffusion models and should be a useful basis for further theoretical and experimental developments. 

Figure 2. Change in membrane potential during uptake and efflux of a neutral amino acid. Ehrlich cells incubated with amino isobutyric acid (AIB) show a transient increase in fluorescence (depolarization) followed by a return to control levels. Upon resuspension (arrow) in AIB-free medium (which results in loss of cellular AIB) fluorescence is decreased transiently (hyperpolarization) followed by a gradual return to baseline values. (From Laris et al. (1978), with permission.)...

Kawahara H, Takeda Y, Tanaka A, Nagano O, Katayama H, Hirakawa M, Hiraki Y (2000) Does diffusion-weighted magnetic resonance imaging enable detection of early ischemic change following transient cerebral ischemia J Neurol Sci 181 73-81... 

Fig. 5.1 Idealized representation of the transient change in fiber and matrix stress that occurs during the isothermal tensile creep and creep recovery of a fiber-reinforced ceramic (the loading and unloading transients have been exaggerated for clarity). It is assumed that the fibers have a much higher creep resistance than the matrix. The matrix stress reaches a maximum at the end of the initial loading transient. After full application of the creep load, the matrix stress relaxes and the fiber stress increases. Upon specimen unloading, elastic contraction of the composite occurs, followed by a time-dependent decrease in fiber stress and increase in matrix stress. Overall, creep tends to increase the difference in stress between constituents and recovery tends to minimize the difference in stress. After Wu and Holmes.15...

Nakamura, M., Araki, M., Oguro, K., and Masuzawa, T., Differential distribution of 68 Kd and 200 Kd neurofilament proteins in the gerbil hippocampus and their early distributional changes following transient forebrain ischaemia, Exp. Brain Res., 89, 31, 1992. 

Respiratory Effects. Following an accident involving a railroad car, 27 individuals were exposed via inhalation to an unspecified concentration of carbon disulfide. Subtle and transient changes in pulmonary function were manifested as reduced vital capacity and decreased partial pressure of arterial oxygen (Spyker et al. 1982). Dyspnea was reported in 77 of the 123 persons following an accidental release of large amounts of carbon disulfide, hydrogen sulfide, and sulfuric acid from a viscose rayon plant in India (Kamat 1994). Exposure concentrations were not stated. 

The second part asked for a prediction of the transient changes in water pressure recorded at two borehole intervals in the close proximity of the advancing tunnel. The pore water pressure record exhibited a marked transient behaviour when the tunnel face was close to the measuring section of the borehole. This transient behaviour was characterized (in one of the measuring segments) by a rather sharp increase in pressure followed by a slow decay as the tunnel moved away from the measuring section. 

This huge multicenter trial demonstrated that there was an increase of hyperthyroidism after the elevation of salt iodization with the highest RR in 1992. For oHTA the incidence increased from 30.5/100000/year in 1987 to 41.7/100000/ in 1992 and decreased to baseline incidence in 1995. In contrast, the incidence of oHGD doubled from 1987 (incidence 10.4/100,000/year) to 1993 (20.9/100,000/ year) and was still high in 1995 (18.0/100000/year). From this study, it can be concluded that increase in iodine supply (change from IDA to ISA) leads to a transient increase, followed by a decrease, in thyroid autonomy, but to a permanent increase in Graves disease. 

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