Selective constraints

Unlike the other two tests, this is associated with each measurement. Reconcihation is required before this test is apphed, but no further isolation is required. However, due to the limitations in reconciliation methods, some measurements can be inordinately adjusted because of incorrectly specified random errors. Other adjustments that do contain gross errors may not be adjusted because the selected constraints are not sensitive to these measurements. Therefore, even though the adjustment in each measurement is tested for gross error, rejection of the mill hypothesis for a specific measurement does not necessarily indicate that that measurement contains gross error. 

However, there is a mathematical method for selecting those variables that best distinguish between formulations—those variables that change most drastically from one formulation to another and that should be the criteria on which one selects constraints. A multivariate statistical technique called principal component analysis (PCA) can effectively be used to answer these questions. PCA utilizes a variance-covariance matrix for the responses involved to determine their interrelationships. It has been applied successfully to this same tablet system by Bohidar et al. [18]. 

Long-distance mate location that is mediated by pheromones is true communication as defined by Burghardt (1970), in that there are selective constraints on both the females production of the signal and the males response - in other words, selection favors some individuals over others in finding a mate. In a provocative argument, Williams (1992) contended that the female odor used by males for mate location is not a pheromone, because in moths there is no special machinery ... 

If it is important to maintain good temperature control and heat transfer is limiting, we would expect that the feed flowrate could be increased if the heat transfer coefficient is larger, if the heats of reaction are lower, or if the heat transfer area is larger. However, faster feed flowrates increase the concentration of B in the reactor and produce more undesirable D. The result is that, for specified conversion and selectivity constraints, the optimum feed trajectory depends very little on all of parameters except the ratio of the base reaction rates ki/k2 at 40°C. 

Increasing the conversion and selectivity constraints to 85% for the same smaller value of 2 reduces the productivity, as shown in Figure 4.55. 

Fig. 4.3.3. El ongation of the primer hybridized to the 5 -biotinylated template requires polymerization along a homopolymeric (dA)sa stretch. In the sole presence of fluorescence-labeled deoxynucleoside triphosphates (dye = tetramethylrhodamine, TAMRA), this selective constraint forces the multiple successive...

Local-rank constraints are related to mathematical properties of a data set and can be applied to all data sets, regardless of their chemical nature. These types of constraints are associated with the concept of local rank, which describes how the number and distribution of components varies locally along the data set. The key constraint within this family is selectivity. Selectivity constraints can be used in concentration and spectral windows where only one component is present to completely suppress the ambiguity linked to the complementary profiles in the system. Selective concentration windows provide unique spectra of the associated components, and vice versa. The powerful effect of these type of constraints and their direct link with the corresponding... 

Codon positions Selective weighting of first, second, and third codon positions in translated genes, because of redundancy of genetic code. A general rule is that third-codon positions are under less selective constraint than first and second and, as such, are more... 

Synonymous versus non-synonymous change assumes that base frequencies reflect substitutional frequencies Unlike synonymous mutations, nonsynonymous changes alter primary sequence of a polypeptide and, as such, are under greater selective constraint and occur less frequently. Nonsynonymous mutations therefore warrant greater weight... 

Clement, C. A., and Gentner, D. (1991). Systematicity as a selection constraint in analogical mapping. Cognitive Science, 15, 89-132. 

Amorphous silica alumina gives a product containing more aromatics, less total olefins, and more highly-branched olefins, confirming the shape-selective constraints of ZSM-5. 

The present paper describes the phenomena of shape-selective polymerization involved in converting C--C olefins over HZSM-5 to higher boiling olefins and the similarities and differences compared to amorphous silica-alumina. The channel systems of ZSM-5 (8), Figure 1, impose shape-selective constraints on the shape of the large molecules accounting for the differences with amorphous catalysts. 

The absence of the more highly branched olefins and less aromatics over ZSM-5 are both indicative of shape-selective constraints. 

Two or more genotypes are neutral in evolution when the selection constraint is unable to distinguish between them. Early sequence comparison data [6] apparently confirmed Motoo Kimura s idea of neutral drift in population genetics [5]. Accordingly, many different genotypes could give rise to the same phenotype, and depending on the conditions, different phenotypes can share the same fitness value. Direct evidence for neutral evolution under controlled conditions came only two years ago Se-... 

Evidence for the relaxation of selective constraints on TAS2R genes in apes and humans does not preclude the possibility that... 

Wang X, Thomas SD, Zhang 1. Relaxation of selective constraint 91. and loss of function in the evolution of human bitter taste receptor genes. Hum. Mol. Genet. 2004 13 2671-2678. 

A selectivity constraint is imposed, in order to maintain the formation of the secondary products at a low value. All the constraints are introduced as inequality type constraints. 

Containment constraint - the key of one relation is the same as the key of another relation. The instance of one key is a subset of the instances of another relation. This relationship is like the selection constraint, but not easily quantifiable. 

Depending on the quality of data and the method selected, constraints on the parameters to be estimated may be required in order to get a chemically meaningful solution. In the case of multivariate curve resolution (MCR) (see Section 3.2) performed on one 2D NMR spectrum, application of constraints is mandatory. If constraints are not applied, it can be shown that there is an infinity of equally well-fitting solutions and hence the true underlying parameters (spectra, concentrations) cannot be estimated directly. This is known as the rotational ambiguity of two-way low-rank models. 

---