Caveats and Cautions

There are a number of attempts to provide quantitative answers in the htera-ture, but these are generally flawed from either a cost engineering or chemical engineering perspective and their results should be treated with extreme caution. This caveat notwithstanding, it is probably reasonable to say that for most products the threshold hes in the range of 1000—10 000 tonne per year process stream (not product) rate. The threshold value will not, however, be the same for aU products, processes, operating sites, and so on. 

In Table I are listed comprehensive citations of published methods for analyses of trace metals In body fluids and other clinical specimens by means of electrothermal atomic absorption spectrometry. Readers are cautioned that many of the early methods that are cited In Table I have become outmoded, owing to Improvements In Instrumentation for electrothermal atomic absorption spectrometry. All of the published methods need to be critically evaluated In the prospective analyst s laboratory before they can be confidently employed for diagnostic measurements of trace metals In body fluids. Despite these caveats, the author believes that Table I should be helpful as a guide to the growing literature on clinical and biological applications of electrothermal atomic absorption spectrometry. 

It is always easy to calculate idealized scattering curves for perfect networks. The experimental systems vary from the ideal to a greater or lesser degree. Accordingly, any estimate of the correctness of a theoretical analysis which is based on an interpretation of experiment must be put forth with caution since defects in the network may play a role in the physical properties being measured. This caveat applies to the SANS measurement of chain dimensions as well as to the more common determinations of stress-strain and swelling behavior. 

In addition to identifying protein partners, yeast two-hybrid technology can be used to identify and study in detail the interaction domains between two proteins. Here, bait and/or fish truncation or deletion constructs of the parent proteins are engineered and characterized as described earlier (see 3.1 Selection and characterization of bait constructs). These are then investigated for association in a yeast two-hybrid interaction assay. Once the BD has been identified, it can be further refined by mutagenesis. The same caveat applies to these studies as for the identification of associating proteins, i.e., it is assumed that the respective fusion proteins fold and adopt the same or a similar three-dimensional conformation to the native protein. This is not always the case and results should be interpreted with caution and if possible, always validated by an alternative experimental approach. O Table 19-1 shows an example of mapping the... 

Thus the response of a spatially uniform system in thermodynamic equilibrium is always characterized by translationally invariant and temporaly stationary after-effect functions. This article is restricted to a discussion of systems which prior to an application of an external perturbation are uniform and in equilibrium. The condition expressed by Eq. (7) must be satisfied. Caution must be exercised in applying linear response theory to problems in double resonance spectroscopy where non-equilibrium initial states are prepared. Having dispensed with this caveat, we adopt Eq. (7) in the remainder of this review article. 

The mere fact that these effects cannot be simulated by one-particle models does not discount their existence. These remarks should be read as a caveat not to interpret the well-known I I.J model and calculation as final, despite the excellent agreement with spectroscopic observation which, incidentally, relies on the same assumption of a vibrating diatomic molecule. It is not suggested that the calculated results be rejected, but to be used with the necessary caution. As a free molecule, Ht is almost certainly of spherical symmetry, and the same probably applies to all diatomic molecules. 

The list of caveats is endless. With that caution in mind, Tables 12.5 and 12.6 give a compilation of dyes used in a variety of thermoplastic resin types. They are listed by color and within color range and by common chemical types employed. Table 12.7 provides the same information for thermosets. In the tables, dye types marked with a W are widely used, those with an L have limited use, and those with an N should not be used. 

Now that we have examined some of the mathematical details of the quantum mechanical treatment of the hydrogen atom, we need to consider what it all means. What is a wave function, and what does it tell us about the electron to which it applies First, a warning There is always danger in taking a mathematical description of nature and using our human experiences to interpret it. Although our attempts to attach physical significance to mathematical descriptions are quite useful to us as we try to understand how nature operates, they must be viewed with caution. Simple pictorial models of a particular natural phenomenon always oversimplify the phenomenon and should not be taken too literally. With that caveat we will proceed to try to picture what the quantum mechanical atom is like. 

To obtain a statistically sound QSAR, it is important that certain caveats be kept in mind. One needs to be cognizant about col-linearity between variables and chance correlations. Use of a correlation matrix ensures that variables of significance and/or interest are orthogonal to each other. With the rapid proliferation of parameters, caution must be exercised in amassing too many variables for a QSAR analysis. Topliss has elegantly demonstrated that there is a high risk of ending up with a chance correlation when too many variables are tested (62). 

The data In Table II are all from our laboratory, although very similar results for ethylene dimers were obtained by Bomse, Cross and Valentlnl ( ). Listed are the mean product kinetic energies , the root-mean-square momenta P g and the lifetimes t. The reader Is cautioned In the use of both tables that error limits and other caveats vary from one system to another... 

The collection of possible causes, consequences, prevalences, and correlations of various brain disabilities in this chapter reminds us that we need to be cautious about labels and numbers. Of particular importance is the necessity for caution about correlations, and a caveat is appropriate here, a caveat also appropriate for other parts of this book. 

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