Precursor amplitude

Asay and Gupta [25] measure elastic precursor amplitudes as functions of propagation distance for two different divalent impurity concentrations in <100)-loaded LiF. It is shown that not only does the presence of divalent ions affect the precursor amplitude, but also that the state of the dispersion plays an important part. It is concluded that, for a given concentration of defects, the rate of precursor attenuation is reduced if the defects are clustered. 

To answer questions regarding dislocation multiplication in Mg-doped LiF single crystals, Vorthman and Duvall [19] describe soft-recovery experiments on <100)-oriented crystals shock loaded above the critical shear stress necessary for rapid precursor decay. Postshock analysis of the samples indicate that the dislocation density in recovered samples is not significantly greater than the preshock value. The predicted dislocation density (using precursor-decay analysis) is not observed. It is found, however, that the critical shear stress, above which the precursor amplitude decays rapidly, corresponds to the shear stress required to disturb grown-in dislocations which make up subgrain boundaries. 

S.E. Arione and G.E. Duvall, Temperature Dependence of the Precursor Amplitude in <111 > Lithium Fluoride, in Shock Waves in Condensed Matter (edited by Y.M. Gupta), Plenum, New York, 1986, pp. 299-302. 

At loading stresses between the HEL and the strong shock threshold, a two-wave structure is observed with an elastic precursor followed by a viscoplastic wave. The region between the two waves is in transition between the elastic and the viscoplastic states. The risetime of the trailing wave is strongly dependent on the loading stress amplitude [5]. 

Figure 4.16. Free-surface velocity profiles measured on 1400° C molybdenum. The free-surface velocity profile is characterized by an 0.05 km/s amplitude elastic precursor, a plastic wave front, and a spall signal (characteristic dip) upon unloading. The dashed lines represent the expected free surface velocity based on impedance-match calculation [Duffy and Ahrens, unpublished].

Fig. 2.7. Elastic precursor decay in which elastic waves are observed to decrease in amplitude with propagation distance is a typical behavior. The data of this figure describe the behavior of crystalline LiF samples of different yield strengths (after Asay et al. [72A02]).

Typical stress-time profiles for the various materials (28.5-at. % Ni, fee and bcc) and various stress regions are shown in Fig. 5.12. The leading part of the profile results from the transition from elastic to plastic deformation. The extraordinarily sharp rise in stress for the second wave in Fig. 5.12(a) and the faster arrival time compared with that in Fig. 5.12(b) is that expected if the input stress is above the transition, whereas the slower rise in Fig. 5.12(b) is that expected if the stress input to the sample is below the transition. The profile in Fig. 5.12(c) for the bcc alloy was obtained for an input particle velocity approximately equal to that in Fig. 5.12(a) for the fee alloy. The bcc alloy shows a poorly defined precursor region, but, in any event, much faster arrival times are observed for all stress amplitudes, as is indicative of lower compressibility. 

N]-, [ C]-, pHjleucine or p Sjmethionine in the case of proteins) for various periods, after which the cells are lysed and the protein of interest is purified (often by immunoprecipitation with specific antibodies). The time course of isotope incorporation gives information about the rate (slope of curve) and extent (amplitude of curve) of the proteins synthesis. To measure degradation, cells are first pulse-labeled (i.e., exposed to radiolabeled precursor for a fixed period, after which sufficient nonla-beled precursor is added to reduce the radiospecific activity of the precursor). Then, the cells are further incubated, and the radiospecific activity of a particular protein of interest is determined (again usually after immunoprecipitation or some other means for achieving its isolation from other cellular proteins). The key point is that the chase allows one to stop radiolabel uptake almost instantaneously, thereby permitting the kinetic... 

Figure 1.S2 Plot of In (/// ) vs. arbitral units proportional to the square of the gradient amplitude for H PGSE diffusion measurements on the cation ofthe five lr(i) catalyst precursors 138a-d, in CDjClj.

Weits No, and the amplitude is not very high to begin with. We have really been trying to look at protein levels to see what is going on with the protein. We don t know. The complication there is that TGFa and its relatives are synthesized as transmembrane precursor proteins that are cleaved by a metalloprotease to release the active peptide. The antibodies only see unreleased TGFa. We have... 

In the ft-a crossover region, typically above 50 °C, the intramolecular co-operativity of the ft motions is such that they can be considered as precursors of the a motions. A direct consequence is that yielding and plastic flow can occur under almost identical stresses, as shown in the strain softening amplitude (Fig. 23). 

Naturally, the first step is to use uncomplexed room temperature CO2/HCI and C02/HBr samples, recording signals with 193 and 222 nm photolysis, respectively. This was done, and several results are presented in Figure 24, which shows OH LIF signals obtained with different wavelengths and precursors. The data are normalized to the photolysis and probe laser fluences, HCl and HBr absorption coefficients, sample concentrations, etc. Signal amplitudes obtained at the OH <-X FlfO.O) bandhead... 

Figure 4.20 Chromatograms recorded in resonant (signal m/z 195 +197) and not-resonant (signal m/z 167 + 169) mode in the analysis of a 1 ppt spiked red wine. Precursor ion m/z 211.9, isolation window 5u.m.a. excitation amplitude 80 V...

The precursors of dendrites, like a cone, were also formed by the square-wave PO with the same amplitude overpotential and the... 

Figure 26. (a) The copper dendrites formed by the pulsating overpotential (PO) regime deposition pulse of 10 ms, pause duration of 100 ms deposition time 18 min (b) The precursor of copper dendrite obtained by PO regime deposition pulse of 1 ms, pause duration of 10 ms deposition time 24 min. In both cases amplitude overpotential used was 1,000 mV. Reprinted from ref. 8 with permission of Elsevier. 

An old example (1992) of Le Bail fit for structure factor amplitude extraction, prior to structure determination by powder difiractometry of the X AIF3 polymorph (conventional Cu X ray data). No isostruc tural phase is known for that metastable compound based on [A1F6] octahedra exclusively connected by corners in a completely new 3D framework, synthesized only in fine powder form, either from organo metallic or hydrated amorphous precursors. The structure was solved by applying the direct methods (no heavy atom), revealing totally the 11 independent atom sites. 

The earliest studies investigating the effects of n-3 dietary fatty acid manipulation on vision date back to the early 1970s. Benolken and others (1973) fed rats a fat-free diet, which resulted in a 60% reduction in the retinal DHA content. This was associated with reductions in the amplitudes of the ERG a-wave (and b-wave), reflecting anomalous photoreceptor function. In a later study, the same authors (Wheeler et al., 1975) studied the effects of feeding rats diets free of fat or supplemented with either n-9, n-6, or n-3 precursors. They determined that rats showed increased ERG amplitudes when fed 2% (w/w) linoleic acid (18 2n-6, LA), but an even greater response when 2% (w/w) a-linolenic acid (18 3n-3, ALA) was used. A mixture of 1% (w/w) LA and 1% (w/w) ALA gave an intermediate response, implying that n-3 fatty acids were critical for the development of optimal retinal function. 

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