Semi-confounding

Variables can often be altered simultaneously, this makes it impossible to later determine which variable caused a given effect. This is known as semi-confounding of effects. 

Richardson, B.J. Lam, P.K.S. Zheng, G.J. McQellan, K.E. De Luca-Abbott, S.B. 2002, BiofouUng confounds the uptake of trace organic contaminants by semi-permeable membrane devices. Mar. Pollut. Bull. 44 1372-1379. 

When a non-constant drift is present, the estimation of the semi-variogram model is confounded with the estimation of the drift. That is, to find the optimal estimator of the semi-variogram, it is necessary to know the drift function, but it is unknown. David (14) recommended an estimator of the drift, m ( ), derived from least-square methods of trend surface analysis (18). Then at every data point a residual is given by... 

Semi-solid flow cells with wired up electrolytes are an intriguing concept which can be applied to both soluble and insoluble chemistries [100, 101]. However, the unique properties that enable desirable electrolyte-level properties present new challenges for cell and system design. First, the electrolytes display non-Newtonian viscoelasticity properties (i.e., Herschel-BuUdey behavior), which confounds both... 

Plate 16.2. Contour plots for electrostatic potential of imidacloprid calculated by a semi-enqtirical molecular orbital method PM3 combined with the AMSOL programme. The plot on the Ufi shows unpolarized imidacloprid, whereas that on the right shows the confound polarized by an ammonium located in the vicinity of the nitro group. Contours are plotted at +/ (ree, zero (yellow) and -1 kccd/mol (blue). A space-filling model cf imidacloprid is shown between the two plots. Reproducedfrom ref. 10 with permission cf Elsevier. 

A brief exposure taste preference device (18, 111) was used In these evaluations to ensure that postingesHbnal factors related to caloric content or digestabllity would not confound preference test results. The whole grain rice volatiles material was the only one found to reliably Increase both consumption and feeding time. In a later semi-field pen test, rice volatiles treated bait was preferred (P <. 05) over whole-grain, granulated, and soy bean oil (1%) treated rice. 

Both the semi-planar, four coordinate Mn porphyrin and the non-planar five coordinate Mn texaphyrin are stable Mn confounds which are capable of using cellular reductants to catalytically deconq>ose peroxynitrite. There is no indication that the in vivo effects of either confound are related to release of fi ee Mn and the lack of therapeutic effect from administration of manganese chloride to G93A mice has been reported previously (44). In addition, we have seen no therapeutic effect of zinc or cobalt analogs of FeTCPP, suggesting fiiat a redox active metal is required such results are consistent with catalytic antioxidant properties. 

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