Definition of terms

Several terms are frequently used to describe DNA mutations and related studies. These terms are defined here to avoid potential confusions. They are divided into three categories (a) general terms, (b) terms that are based on the phenotypic consequences, and (c) terms that are based on DNA sequence changes. 

A clear definition of terms is critical to the snccess of all communication. Particularly in the area of computational chemistry, there is a need to be careful in the nomenclature used to describe predictive tools, since this often helps clarify what approximations have been made in the course of a modeling experiment . For the purposes of this textbook, we will adopt a specific convention for what distinguishes theory, computation, and modeling. 

In general, theory is a word with which most scientists are entirely comfortable. A theory is one or more rules that are postulated to govern the behavior of physical systems. Often, in science at least, such rules are quantitative in nature and expressed in the form of a mathematical equation. Thus, for example, one has the theory of Einstein that the energy of a particle, E, is equal to its relativistic mass, m, times the speed of light in a vacuum, c, squared, 

Such simpliflcations of general theories under special circumstances can be key to getting anything useful done One would certainly not want to design the pendulum for a mechanical 

Essentials of Computational Chemistry, 2nd Edition Christopher J. Cramer 

Occasionally, a theory has proven so robust over time, even if only within a limited range of applicabihty, that it is called a law . For instance. Coulomb s law specifies that the energy of interaction (in arbitrary units) between two point charges is given by 

Equation (1.3) represents a very simple model, and that simplicity derives, presumably, from the small volume of chemical space over which it appears to hold. As it is hard to imagine deriving Eq. (1.3) from the fundamental equations of quantum mechanics, it might be more descriptive to refer to it as a relationship rather than a model . That is, we make some attempt to distinguish between correlation and causality. For the moment, we will not parse the terms too closely. 

Note that z may approach zq from any direction in the complex plane, and the value of the limit t is independent of the direction of approach. 

A function f z) is continuous if it is continuous at every point of its domain. 

Definition A.4 (Neighborhood of a Point) The set of all points z that satisfy the inequality 

Definition A.5 (Set) A point zq is an interior point of a set S if there exists some neighborhood of Zq that contains only points of S. A point zq is an exterior point of the set S if there exists some neighborhood of zq that contains only points that are not in set S. If zq is neither an exterior nor an interior point cfS, it must be a boundary point ofS. 

Definition A.6 (Open and Closed Sets) An open set contains only interior points. If a set contains its boundary points, it is a closed set. 

Consider the chemical reaction represented by the stoichiometric equation 

Experimentally, it is found that the rate of reaction is usually a simple function of the reactant concentrations 

If the rate is directly proportional to the concentration of a single reactant, i.e. 

The order of reaction is not always integral and sometimes the rate cannot be expressed in a simple form. For example, some enzyme-catalysed reactions obey Michaelis—Menten kinetics and the rate is given by 

Some gas—solid heterogeneous reactions follow a similar rate law. Under certain conditions, the rate of hydrogenation of ethene is described by the equation 

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The following are definitions of terms relevant to computational chemistry. These definitions are based on common usage in this field. They do not necessarily reflect the dictionary definitions or those in other branches of science. 

The elastic and viscoelastic properties of materials are less familiar in chemistry than many other physical properties hence it is necessary to spend a fair amount of time describing the experiments and the observed response of the polymer. There are a large number of possible modes of deformation that might be considered We shall consider only elongation and shear. For each of these we consider the stress associated with a unit strain and the strain associated with a unit stress the former is called the modulus, the latter the compliance. Experiments can be time independent (equilibrium), time dependent (transient), or periodic (dynamic). Just to define and describe these basic combinations takes us into a fair amount of detail and affords some possibilities for confusion. Pay close attention to the definitions of terms and symbols. 

Definitions of Terms Used in Powder Metallurgy, MPIF Standard 09, Metal Powder Industries Federation, Princeton, N.J., 1992. 

The first attempt to formulate a systematic nomenclature for polymers was based on the smallest repeating stmctural unit it was pubHshed in 1952 by a Subcommission on Nomenclature of the lUPAC Commission on Macromolecules (95). The report covered not only the naming of polymers, but also symbology and definitions of terms. However, these nomenclature recommendations did not receive widespread acceptance. Further progress was slow, with a report on steric regularity in high polymers pubHshed in 1962 and updated in 1966 (96). 

Fig. 1. Sepaiation in a bottle centrifuge, where X is the initial position of a particle (drop). See text for definition of terms.

Standard Definitions of Terms Relating to Activated Carbon... 

Definition of Terms Following are some definitions that are useful in understanding the components of hazards and risk (CPQRA, 1989, pp. 3, 4). 

FIG. 26-62 Definition of terms for puncture of a vessel or line attached to a vessel. 

Sections II and III describe the types and form of gases, vapors, and particles in the atmosphere. Definitions of terms are offered at the beginning... 

Respiratory protective devices - Definitions of terms and pictograms. Superseded BS 6927 1988... 

Opening segments of the IP2 PRA data analysis section describe the definitions of terms and concepts employed, the assumptions made, and limitations recognized during the data base construction. A set of 39 plant-specific component failure mode summaries established the basis for component service hour determinations, the number of failures, and the test data source for each failure mode given for each component. Generic data from WASH-1400, IEEE Std 500, and the LER data summaries on valves, pumps, and diesels were combined with plant-specific failure data to produce "updated" failure information. All the IP2 specialized component hardware failure data, both generic and updated, are contained in Table 1.5.1-4 (IP3 1.6.1-4). This table contains (by system, component, and failure mode) plant-specific data on the number of failures and service hours or demands. For some components, it was determined that specifications of the system was warranted because of its impact on the data values. 

Figure 12 Monolayer nucleus with uneven end surface (a) definition of terms (b) definition ofAEe and the activation...

A definition of terms, some more related to sieve trays than other types, are provided by Chase [192] (used by permission, Chem. Eng., July 51, 1967) ... 

For definitions of terms used in this section see Section 9.5A. 

Test method for effects of outdoor weathering on pipeline coatings Definitions of terms relating to corrosion and corrosion testing... 

Appendix 7 Definitions of Terms Related to Mass Spectrometry... 

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