Bipolar axes

A bipolar axis is defined by two rows S and s,- in Fig. 31.3e. If we project a column upon this bipolar axis, we reconstruct the difference between two elements in X. This follows readily from eq. (31.22)  

This bipolar axis defines a contrast between the row-variables i and i. Note that a contrast involves the difference of two quantities. 

This bipolar axis defines a contrast between the column-variables j and f. 

In Fig. 31.4b we have constructed a bipolar axis through Cl and Si. Perpendicular projections of the wind directions upon this axis are in the same order as the 

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The distances between compounds in Fig. 31.7 are not notably affected by the transformation in comparison with the previous Fig. 31.6. This biplot allows more easily to perceive the correlations between measurements. Three clusters are now put in evidence, namely (1) DMSO and DMF, (2) ethanol and propanol, (3) octanol, dioxane, THF and methylenedichloride. The line segments drawn from the origin have been added to emphasize these groupings. Unipolar axes could have been defined here in the same way as in Fig. 31.6. Bipolar axes on the column-standardized biplot, however, cannot be interpreted directly in terms of the original data in X. 

The biplot of Fig. 31.9 shows that both the centroids of the compounds and of the methods coincide with the origin (the small cross in the middle of the plot). The first two latent variables account for 83 and 14% of the inertia, respectively. Three percent of the inertia is carried by higher order latent variables. In this biplot we can only make interpretations of the bipolar axes directly in terms of the original data in X. Three prominent poles appear on this biplot DMSO, methylene-dichloride and ethylalcohol. They are called poles because they are at a large distance from the origin and from one another. They are also representative for the three clusters that have been identified already on the column-standardized biplot in Fig. 31.7. 

Fig. 31.9. Biplot of chromatographic retention times in Table 31.2, after log double-centering. Two bipolar axes have been drawn through the representation of the methods DMSO, methylenedichloride...

The analysis of Table 31.2 by CFA is shown in Fig. 31.11. As can be seen, the result is very similar to that obtained by log double-centering in Figs. 31.9 and 31.10. The first latent variable expresses a contrast between NO2 substituted chalcones and the others. The second latent variable seems to be related to the electronic properties of the substituents. The contributions of the two latent variables to the total inertia is 96%. The double-closed biplot of Fig. 31.11 does not allow a direct interpretation of unipolar and bipolar axes in terms of the original data X. The other rules of interpretation are similar to those of the log double-centered biplot in the previous subsection. Compounds and methods that seem to have moved away from the center and in the same directions possess a positive interaction (attraction). Those that moved in opposite directions show a negative interaction (repulsion). 

Unipolar and bipolar axes have been discussed in Section 31.2. Briefly, a unipolar axis is defined by the origin and the representation of a row or column. A bipolar axis is drawn through the representations of two rows or through the representations of two columns. Projections upon unipolar axes reproduce the values in the transformed data table. Projections upon bipolar axes reproduce the contrasts (i.e. differences) between values in the data table. 

This type of biplot does not reproduce distances or angles accurately, especially when A, and 7 are very distinct. It can be shown that the distortion of distances that occurs in the vertical direction is proportional to the square root of The advantage of this type of biplot is that it allows us to construct bipolar axes for any... 

Fig. 32.10. CFA biplot computed from the data in Table 32.10. Factor scaling coefficients were defined as a = P = 0.5. This definition allows us to draw bipolar axes through the four educational categories, showing the contrast between women and men (horizontally) and between chemistry and other fields (vertically).

The spectral map shows three distinct poles of specificity. These are respectively the p-receptor (DHM), the 6-receptor (DADLE) and the K-receptor (EKC). The naloxone receptor (NAL) appears to be strongly correlated with the p-receptor (DHM) and, hence, provides little additional information. In spectral map analysis, correlation between variables, as well as similarity between compounds, is evidenced by the proximity of their corresponding symbols. The lines drawn through the three poles of the map represent bipolar axes of contrast. A contrast is defined in this context as a log ratio or, equivalently, as a difference of logarithms. For example, the horizontal axis through the p- and 8-receptors defines the p/6 contrast. Compounds that project on the right side of this axis bind more specifically to the p-receptor, while those that project on the left side possess more... 

The disadvantages appear to be that the bipolar membranes are comparatively expensive, and the economic life is limited to about one year. Such short lifetime appears to result from the very high (- 10 V/cm) voltage gradients at the interface between the AX and CX regions. Additionally, practical current densities are limited to about 1000 A/m available area. 

Bipolar ED. Bipolar ion-exchange membranes have one surface consisting of CX resin and the opposite surface of AX resin. The interface between the CX and AX resins may be regarded as a zero gap ED compartment. When a direct current is passed through such a membrane in a direction to pull anions out of such interlace and through the AX resin, the interface rapidly becomes depleted of all ions other than those resulting from the dissociation of water. Dilute alkali can therefore be produced at the outer surface of the AX region and dilute acid at Ihc outer surface of the CX layer. 

Drug-drug interactions Carbamazepine and valproate The mood stabilizers carbamazepine and valproate are often used in combination with antidepressants in patients with unipolar or bipolar affective disorder. The effects of valproate and carbamazepine on the steady-state pharmacokinetics of moclobemide and two metabolites have been studied in a non-randomized crossover study in 21 patients with unipolar depression [3 ]. Valproate had no effect, but carbamazepine was associated with a 35% reduction in moclobemide AUC, a 28% reduction in C ,ax, and a 41% reduction in clearance after 4 weeks of co-administration. These changes were interpreted as being due to induction carbamazepine of the metabolism of moclobemide and its main metabolite. However, there was no concurrent loss of efficacy, throwing into doubt the clinical significance of these significant kinetic effects. 

At present, there are few reliability reservations about bipolar TTL and LPSTTL these are made essentially for the professional market and semiconductor manufacturers have responded to the pressure for a better product. Power transistors in general are also satisfactory, they use a unimetallisation/wire bond system (Au/Au or All AX) and the encapsulant is normally a silicone. Small signal transistors are largely aimed at the non-professional market their quality and reliability are usually poor (but adequate for their intended application). CMOS and ISOCMOS are particularly sensitive to moisture, but some manufacturers have demonstrated that they can produce a reliable product and. 

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