Variable expressivity

If you try to solve these n equations for all of the elements of the v veetor (vi...Vn), you ean eliminate one variable using one equation, a seeond variable using a seeond equation, ete., beeause the equations are linear. For example you eould solve for vi using the first equation and then substitute for vi in the seeond equation as you solve for V2, ete. Then when you eome to the nth equation, you would have n-1 of the variables expressed in terms of the one remaining variable, Vn. 

Time domains and frequeney domains are related through Fourier series and Fourier transforms. By Fourier analysis, a variable expressed as a funetion of time may be deeomposed into a series of oseillatory funetions (eaeh with a eharaeteristie frequeney), whieh when superpositioned or summed at eaeh time, will equal the original expression of the variable. This... 

Table 1-8 lists the transforms of some common time-variable expressions. 

With so many variables, expressions for convective heat flow cannot be as simple as those for conduction. The interpretation of observed data has been made possible by the use of a number of groups which combine the variables and which can then be used to estimate convective heat flow. 

The size component which may be strongly present (as in this chromatographic application) is eliminated by the operation of double-centering. Hence, double-centered latent variables only express contrasts. In column-centered biplots one may find that one latent variable expresses mainly size and the others mainly contrasts. In general, none of the latter is a pure component of size or of contrasts. If we want to see size and some contrasts represented in a biplot, column-centering... 

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). 

Gottlieb B, Beitel LK, Trifiro MA. Somatic mosaicism and variable expressivity. Trends Genet 2001 17[2] 79—82. 

Alternative equations of state may be derived from Eq. (15). For example, one can obtain an equation of state in terms of variables expressed relative to their values at the melting point. At the melting point, the reduced variables 7rm, rm, and 6m are universal constants. This is illustrated in Table I where rm is given for several salts. Except for the lithium halides, which are not expected to follow this development since the small radius of the lithium ion leads to anion-anion contacts, rm is reasonably... 

Reduced penetrance and variable expressivity are factors that influence the effects of particular genetic changes. These factors usually affect disorders that have an autosomal dominant pattern of inheritance, although they are occasionally seen in disorders with an autosomal recessive inheritance pattern. 

Although some genetic disorders exhibit little variation, most have signs and symptoms that differ among affected individuals. Variable expressivity refers to the range of signs and... 

As with reduced penetrance, variable expressivity is probably caused by a combination of genetic, environmental, and lifestyle factors, most of which have not been identified. If a genetic condition has highly variable signs and symptoms, it may be challenging to diagnose. 

Cohen AJ, Bunn PA, Franklin W, Magill-Solc C, Hartmann C, Helfrich B, Gilman L, Folkvord J, Helm K, Miller YE (1996) Neutral endopeptidase Variable expression in human lung, inactivation in lung cancer, and modulation of peptide-induced calcium flux. Cancer Res 56(4) 831-839. 

Bruchert V, Knoblauch C, Jorgensen BB (2001) Controls on stable sulfur isotope fractionation during bacterial sulfate reduction in Arctic sediments. Geochim Cosmochim Acta 65 763-776 Bryan BA, Shearer G, Skeeters JL, Kohl DH (1983) Variable expression of the nitrogen isotope effect associated with denitrification of nitrate. J Biol Chem 258 8613-8617 Canfield DE (2001) Biogeochemistry of sulfur isotopes. Rev Mineral Geochem 43 607-636 Chau YK, Riley JP (1965) The determination of selenium in sea water, silicates, and marine organisms. Anal Chim Acta 33 36-49... 

Autosomal dominant diseases are more likely to show late onset of symptoms. The genes involved often encode noncatalytic proteins, and may occasionally show incomplete penetrance or variable expression in a pedigree. 

This late-onset autosomal dominant disease exhibits variable expression. Many heterozygotes remain symptom-free throughout their lives. Signs and symptoms, when present, include ... 

I Recurrence risks can be predicted by drawing Punnett squares, j Principles that can characterize single gene diseases j Variable expression in severity of symptoms... 

Variable expression (choice B) refers to differences in the severity of a disorder but does not refer to the complete absence of the disorder, which is incomplete penetrance. 

Although variable expression (choice A) is a characteristic of this disease, other femily members (including a parent) would be likely to manifest at least mUd expression of the disorder. 

Allelic heterogeneity is observed in osteogenesis imperfecta (choice A), but allelic heterogeneity causes variable expression in patients and is not the principle described here. 

Familial hypocalciuric hypercalcemia is inherited in an antosomal dominant manner with almost 100% penetrance but variable expressivity. The FHH locus was first mapped to 3q21-24 by linkage analysis (47). Most FHH families map to the long arm of chromosome 3, but one clearly maps to another locns, 19pl3.3 (44). 

The intrinsic variable expressed usually as international units (U) of enzyme activity per milligram protein... 

The intrinsic variable expressed as units of radioactivity (in becquerels or, more traditionally, curies) per mole of a substance. One Bq corresponds to 1 disintegration per second (dps) and one Ci to 3.70 x 10 ° Bq. This parameter is especially useful in quantifying the amount of substance in biological samples. For example, if SAs is the standard specific radioactivity (say, x dps/y mol) of a standard, and if SAg is the experimental specific activity (say, x dps/(y + z) mol), then the content z in a sample can be determined from the expression (SAs/ SAe) = (y + z)/y or z = y ([SAj/SAg] - 1). This intrinsic variable can also be expressed as the gram-atom excess of a stable isotope per mole of a substance. The numerator is typically determined using a ratio mass spectrometer, and the denominator can be estimated by chemical and/or spectroscopic techniques. 

B. Variable expression arises when the nature and severity of the phenotype for a genetic condition varies from one person to another. 

The answer is B. The clinical symptoms in this case strongly suggest a mitochondrial disorder affecting both neurologic and musculoskeletal functions. In such cases, no male-to-male transmission is possible because the mother s ovum provides all the cytoplasmic components, including the mitochondria, for the fertilized egg. A pedigree for this family would resemble the inheritance pattern of an X-linked disorder with the likelihood of variable expression. 

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