Norms of reactions

Sarkar, S. (1999), From (tie Reaklionsnorm to the adaptive norm the norm of reaction, 1909- I960 , Biology and Philosophy, 14, 235-252. 

Ken Schaffner Just a very brief comment before we go on. About three years ago, I was doing some work on C. elegans, and I asked Corey Bargman about norms of reaction. She s a distinguished UCSF experimentalist. She said she had never heard about it. At least in that term. After I described what it was, she said oh wait, we use that . But she d never heard of the terminology, and I suspect that it s just not widespread in the molecular community. 

Sohotra Sarkar By the way, one of the reasons why the paragraphs describing the importance of the norm of the reaction disappeared from the book is because one of the referees who read the book, reacted to those two paragraphs by claiming that the norm of reaction was the most useless thing ever introduced in genetics. 

Alex Rosenberg. This partly reflects the ideological split between Lewon-tin and some others with respect to the acceptance and the interpretation of molecular biology. The norm of reaction, as a concept, is closely associated with Lewontin, and as you point out both in your book and today, has an interesting Soviet pedigree. 

In a variety of environmental conditions the extent to which you can change a sign, is limited by its norm of reaction. This term was proposed by 1.1. Schmalhausen (1969) and is special an individual characteristic, reflecting the breadth of variability in body shap>e in response to exposure to the environment and the ongoing without changing its genotyp>e (Severtsov, 2004). 

Severtsov, AS. Surova, G.S. (1981). Individual variability o norm of reaction and adaptation of population. Zhumal obshei biologii T XLII, No2, pp. 181-192. (Russ.). Severtsova, E. A (2002) Adaptive processes and variability of embryogenesis of anuran omfMrians in urban popidations. Synopsis PhD thesis M. MSU. 2002 24 p russ. 

Norm (Standard) norm of reaction Reaktionsnorm normal distribution Normalverteilung nosepiece/... 

The history of the norm or reaction has been reconstructed by Sarkar (1999) - historical details in the rest of this paragraph are from this source. 

Sohotra Sarkar. Yes, and in fact the only reason the molecular work is being done right now - partly I agree with Alex - is those of us who do some of that work do not talk about the norm of the reaction at all, we replace it by talking about plasticity, but it s a cluster of concepts very connected to each other. 

The source of some of the difficulties encountered in trying to explain the effects of structural changes on ionization rates may be due to the different parts played by the solvent, as for example, the sulfur dioxide of the trityl chloride equilibrium experiments and the aqueous acetone of the benzhydryl chloride rate data. The solvent is bound to modify the effect of a substituent, and although the solvent is usually ignored in discussing substituent effects this is because of a scarcity of usable data and not because the importance of the solvent is not realized "... solvation energy and entropy are the most characteristic determinants of reactions in solution, and... for this class of reactions no norm exists which does not take primary account of solvation. 220 Precisely how best to take account of solvation is an unanswered problem that is the subject of much current research. 

Figure 8. (a) Pulse sequence resulting from optimization of the control field to generate H in the same reaction as studied in Fig. 6. (6) The Husimi transform of the pulse sequence shown in (a). (c) Time dependence of the norms of the ground-state and excited-state populations as a result of application of the pulse sequence shown in (a). Absolute value of the ground-state wave function at 1500 au (37.5 fs) propagated under the pulse sequence shown in (a), shown superposed on a contour diagram of the ground-state potential energy surface. (From D. J. Tannor and Y. Jin, in Mode Selective Chemistry, B. Pullman, J. Jortner, and R. D. Levine, Eds. Kluwer, Dordrecht, 1991.)...

Wiberg and coworkers published relative rate constants and the products of reaction of silene 6 with a number of alkenes and dienes in ether solution at 100 °C6 106-108. These data are listed in Table 2 along with an indication of the type of product formed in each case. As is the norm in Diels-Alder additions by more conventional dienophiles, the rate of [2 + 4]-cycloaddition of 6 to dienes increases with sequential methyl substitution in the 2- and 3-positions of the diene, as is illustrated by the data for 2,3-dimethyl-1,3-butadiene (DMB), isoprene and 1,3-butadiene. The well-known effects of methyl substitution at the 1- and 4-positions of the diene in conventional Diels-Alder chemistry are also reflected with 6 as the dienophile. For example, lruns-1,3-pen tadiene reacts significantly faster than the f/.v-isorrier, an effect that has been attributed to steric destabilization of the transition state for [2 + 4]-cycloaddition. In fact, the reaction of c/s-l,3-pentadiene with 6 yields silacyclobutane adducts, while the trans-diene reacts by [2 + 4]-cycloaddition108. No detectable reaction occurs with 2,5-dimethyl-2,4-hexadiene. The reaction of 6 with isoprene occurs regioselectively to yield adducts 65a and 65b in the ratio 65a 65b = 8.5 (equation 50)106,107. 

Most of the ion exchange reactions that occur in soils involve three or more principal ions. For example, in soils at pH < 4, the trio H+, Ca2+, Al3+ might be considered, and, in soils at pH > 7, the set Na+, Mg2+, Ca2 is important.1 Multicomponent cation exchange is the norm for reactions on humic substances13 and the same is true for anion exchange on metal oxides (e.g., CE, NOJ, and SO4 on iron or aluminum oxyhydroxides).14... 

Of course, curly braces will also identify an inner product and a norm in the infinitedimensional Hilbert space of reactions. While the latter is infinite dimensional just the same as the space of components, one should be careful in generalizing results from finite-dimensional vector spaces, as the discussion in the following shows for some simple problems. 

Comparison of reaction rates, called rate-of-production analysis, is a frequently applied technique and is the basis of limiting the size of a newly created mechanism. However, this technique requires a lot of manual effort. Algebraic rate sensitivities are the partial derivatives of production rates with respect to rate parameters. These measures are equal to normed reaction rate contributions. Inspection of algebraic rate sensitivities, based on either the sum of squares of the coefficients (overall sensitivities) or principal component analysis, is a simpler and more automatic way for the identification of redundant reactions than that based on rate-of-production analysis. 

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