INDEX mixed-layering

Figure 5 Compilation of the U37 index of mixed-layer particulates in relation to in situ temperature (Conte et al., in press). The heavy solid line indicates the linear Prahl et al. (1988) paleotemperature relation used for sediment estimates.

It should be possible to test the fidelity of alkenone SST reconstructions with an independent paleothermometer such as 5 0. There are a number of reasons why this comparison is not straightforward, however. First, many planktonic foraminifera live below the mixed layer for part or all of their life cycle. Comparing their isotopic temperatures with the unsaturation index of the alkenone producers, which must live in the photic zone, may not yield consistent estimates of past temperature changes. Many foraminifera have seasonal cycles of production far more pronounced... 

The relationship observed in sediments closely mimics the relation measured between unsaturation in photic zone particulates (Conte et al. in press) and in situ temperature. We should note, however, that the calibration of sedimentary U 7 to mean annual SST represents a statistical relationship and should not be interpreted in too simphstic a manner. We have seen above that this relation holds for sediments because alkenone synthesis generally occurs in the mixed layer, and because alkenone production by selected hapto-phyte algae is less seasonal than many other planktonic groups. Lurthermore, temperatures during the season of maximal alkenone production generally come close to mean annual SST. The index, therefore, is a quite robust proxy for mean annual temperature. It should be kept in mind that regional variations in the factors that control the depth and seasonality of alkenone production can cause the index to deviate from mean annual SST. 

Toler, L. G., and J. Hower, 1959. Determination of mixed-layering in glauconites by index of refraction. Am. Mineralogist 44 1314. 

For laminar flow - flow in whieh the layers of fluid are stratified aeross whieh there is no mixing apart from that due to moleeular diffusion - Stokes Law (Stokes, 1851) applies. Firstly, however, it is neeessary to define an index of the flow to indieate whether it is laminar or turbulent. This is done through the... 

A simple test to estimate the interfacial layer thickness is to measure the thickness of the bottom layer before and after spinning, exposure, and development of the top layer. The difference is taken to be the thickness of the interfacial layer for comparison purposes. In reality, the mixing is continuous and the development of the top layer stops inside the interfacial layer instead of at its edges precisely. Furthermore, the test in Reference 26 relies on the IBM Film Thickness Analyzer to measure the resist thickness for convenience. Since this tool operates on the principle of spectral reflectivity changes caused by film thickness changes, a uniform refractive index is important. When some part of the interfacial layer still remains, the measurement can be erroneous in principle. 

Figure 2.3a (at a gas velocity slightly above the lower of fhe fwo minimum fluidizing velocifies) shows that a layer of pure jefsam develops at the bottom of fhe bed whilsf above this the remainder of fhe bed contains a lower, but near uniform, concentration of jefsam x). As the fluidizing gas velocify increases fhe concentration of jetsam in the bed becomes more uniform and approaches the nominal average concentration in the whole bed Xj (Figure 2.3c). The degree of mixing in such cases can be quantified using a mixing index M defined as...

Mix and place in the distilling tube, arranging the thermometer so that it nearly touches the bottom of the tube. Heat with a free flame to 285-290°. Move the burner to and fro so that the heat is directed towards all sides of the tube. When the mixture has melted, adjust the flame so that the temperature remains about 290°. If the temperature is allowed to rise above 295°, adipic acid distills over and the side tube becomes clogged. Continue the distillation until only a small residue remains in the flask. Add 2 ml of saturated salt solution to the receiving tube, insert the separatory stopper, shake gently, and then withdraw the lower aqueous layer. Dry with 0.5 g of anhydrous calcium chloride and distill. The yield is 1.3-1.5 g. If a refractometer is available, determine the refractive index of your product. 

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