Definitions and measurements

Danckwerts, P. V. (1953). The definition and measurement of some characteristics of mixtures. Applied Scientific Research A3, 279-296. 

Aromaticity, defined as a structural feature, was used as a predictive tool for compounds that had not been prepared previously, whereas reactivity, bond length, or magnetic criteria had to await the isolation of a compound and its experimental investigation. Only recently has the development of quantum-chemical methods reached the point where one can predict with sufficient accuracy the magnetic properties, the bond lengths, and the reactivity patterns of aromatics. The multidimensional character and the definition and measurement of aromaticity generated confusion and conflicts.43 A recent review discussed the multidimensional character of aromaticity and theoretical and experimental approaches to aromatic structures and their predictions, and references are indicated extensively.66... 

There was, then, a certain degree of accuracy in the alchemical description of the processes we now call chemical changes, as being the removal of the outer properties of the things which react, and the manifestation of their essential substance. But there is a vast difference between this description and the chemical presentment of these processes as reactions between definite and measurable quantities of elements, or compounds, or both, resulting in the re-distribution, of the elements, or the separation of the compounds into their elements, and the formation of new compounds by the re-combination of these elements. 

Moore RY, Speh JC, Card JP 1995 The retinohypothalamic tract originates from a distinct subset of retinal ganglion cells. J Comp Neurol 352 351—366 Morris ME, Viswanathan N, Kuhlman S, Davis PC, Weitz CJ 1998 A screen for genes induced in the suprachiasmatic nucleus by light. Science 279 1544—1547 Mrosovsky N 1999 Masking history, definitions, and measurement. Chronobiol Int 16 415-429... 

Until now, we have been primarily concerned with the definition and measurement of viscosity without regard to the nature of the system under consideration. Next we turn our attention to systems containing dispersed particles with dimensions in the colloidal size range. Viscosity measurements can be used to characterize both lyophobic and lyophilic systems we discuss both in the order cited. 

Let us consider each issue in turn the definition and measurement of patient compliance, and the value of information about patient compliance and its correlates in a changing health care environment. 

Elementary mechanical work forms were considered in Section 2.8. In the present section, we present a broader overview of the varieties of work that are commonly encountered in thermodynamic investigations. The goal is to introduce experimental techniques and operational terminology that underlie the definition and measurement of each work type. We also draw attention to formal patterns among the different forms of work that anticipate their unification with heat in a generalized energy-conservation principle. 

The first property of solvents to be considered is the dielectric constant, e. The dielectric constant of a substance measures the reduction of the strength of the electric field surrounding a charged particle immersed in the substance, compared to the field strength around the same particle in a vacuum. The dielectric constant is a macroscopic property that is, its definition and measurement... 

In the world of particles and powders, there are many properties and there is a multitude of property definitions and measuring techniques, which may even vary from one industry to another. There is a need to standardise the definition and measurement of these properties. This will help streamline definitions and measurement techniques to those that are most applicable. It will help in obtaining greater reproducibility and also enable greater comparison of work undertaken by different groups. 

American Academy of Sleep Medicine Task Force. Sleep related breathing disorders in adults recommendations for syndrome definition and measurements techniques in clinical research. Sleep 1999 22 667-689. 

Figure 1.5 Components of the spin polarization vector P of ejected photoelectrons. The direction of the photoelectron is given by the polar and azimuthal angles and O (see Fig. 1.4). For an ensemble of electrons emitted in this direction, the polarization vector P then points in a certain direction in space, and one possibility for representing this vector using three orthogonal components is shown in the figure Plong in the direction of the photoelectron and P,ransX and P,ranS both perpendicular to this direction (for the definition and measurement of these components see Section 9.2.1).

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