Field variations, measured

Our understanding of seasonal and interannual variation in global terrestrial vegetation dynamics is, however, very sketchy at present. Ecosystem respiration measurements have been made for various soil-vegetation types for variable lengths of time Relationships between ecosystem respiration and weather data have been derived from these data for four major biomes 88), However, additional systematic collection of field respiration measurements would be necessary for placing much confidence in such a relationship. 

Since, during an actual measurement, the shuttling process is repeated many times in a cyclic manner, the technique has been named field-cycling (FC) NMR relaxometry, a term which underlines the fact that it is the magnetic field variation that matters and not the manner in which it is achieved. 

Figure 14 In (a) is shown the variation of the susceptibility with temperature for a Bi2Ca2Mn06+y crystal obtained while warming the sample in a field of 500G after having cooled the sample in zero field. The magnetization vs. field curve measured at 10K on the same sample is shown in (b).

The effect of field variations on measured mobility are considerable and discussion of this in terms of double layer relaxations provides the major thrust of Stotz paper. When the field is applied to a particle and its double layer, the particle moves in one direction relative to the double layer and there is, therefore, an induced asymmetry. The relaxation time required to restore the original symmetry can be defined as... 

Electrical conduction in the Mantle The magnitude and mechanism of electrical conductivity within the Earth have also been studied extensively. The radial distribution of electrical conductance in the Earth s interior may be estimated from studies of secular variations of the Earth s magnetic field. These measurements indicate a steep increase of electrical conductivity between depths of 400 and 1,000 km in the Mantle... 

This approach is similar to the use of the field variation of the centre of gravity of the MAS centreband, but has the advantage that the narrower, more symmetric line makes determination of the correct position of the centre of gravity more precise. For experiments carried out at two magnetic fields where the Larmor frequencies are voi and vo2 for the measured DOR peak positions (in ppm) at the two magnetic fields of 8dori,2 then... 

It has been pointed out in the experimental section of the paper that kinetic data of surface processes can only be obtained if all adsorbed molecules are completely desorbed by each field pulse. This requirement can be checked from field strength variation measurements. Fig. 2 displays the results of such an experiment performed with a Ru emitter. The measurements are performed at a pres--4... 

Field strength variation measurements have also been performed for NO on Pt. The detailed results will be published elsewhere. It is found that the chemical dissociation of N0ad is strongly face dependent.While the stepped surface region with (001) orientation of the terraces (furtheron denoted as stepped (001)) is active in N-0 bond breaking, the stepped (111) surface is not. 0ad formation on stepped Pt(001) leads to the detection of 0+ and Pt0n+ (n=l,2) ions. PtO species from high index planes are not present in the mass spectra. 

If the film cannot be freely deformed in its plane, the piezoelectric current is called t/33 or dj. If the variation in the electric field is measured per unit of stress, g coefficients are obtained that are connected by the correlation of g = d/e where e is the dielectric constant depending on the film thickness. Constants g and tf are most widely used in the design of electromechanical transducers. The yield from the conversion of mechanical energy into electrical energy is represented by the electromechanical coupling coefficient ATjby Eq. (3.3). 

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