Manifestations of Similarity

In the scientific context, the attempt is made to reduce the importance of diagnostic criteria to an absolute minimum. Fortunately, this is comparatively easy to do when dealing with chemical entities such as structural formulas, for their emotive impact is dearly very small. Moreover, similarity measures can be adopted that are algorithmic in nature, i.e. measures that involve no actual similarity calls. Tversky [20] has also investigated an asymmetry in similarity calls that can arise when the sequence of the presentation of objects is altered. This problem is typically encountei when one of the objects being compared is regarded as a prototype. In comparison of circles and ellipses, for instance, experimental observers consistently reported that ellipses were more similar to circles than drcles to ellipses. The rule here appears to be that a variant will 

Two pairs of moleoilar fractures, one pair showing identical structures and the other pair different structures. Surprisingly, it takes longer to identify the differing pair than the identical pair. The structures represent drug molecules known to be active against the HIV virus that causes AIDS 

The end result of the various difficulties encountered in the assessment of similarity is that it is not possible to define any absolute measures of similarity. All similarity determinations are thus relative and the best that can be done is to define relative measures of similarity. This is not necessarily a major drawback, for even relative similarities can be extremely valuable to chemists. In fact, relative similarities have found widespread expression in many different chemical contexts. In the process of accommodating the concept to the manifold roles it has been required to play, the concept has become ever more elaborated. Currently, we have at our disposal a wide range of varieties and subvarieties of similarity several of the varieties are listed in Table 2. One of these varieties -analogy - has already been mentioned in our introduction this particular variety 

Classification of nonrigid molecule states Longuet-Higgins 1963 

At this point we move on to a more mathematical characterization of analogy. The concept of analogy has been subdivided into at least five varieties  

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It is obvious that this very strongly undermines the entire issue of quantifying aromaticity. In the spirit of Kekule one might opt not to rely on manifestations of similarity to benzene in a range of properties but rather express benzene likeness directly in some fundamental property such as the electron density. This has been done before but only for molecules consisting of benzenoid rings [25-27]. There is, at the moment, no clue on how to compare a molecule that differs so much from benzene as for instance a square planar four-membered all-metal ring as will be considered here. 

Combustion is the entire process by which something is oxidized. It is part of the use of gasoline or diesel fuel in automobiles and trucks, as well as part of propulsion in aircraft either in jet engines or propeller engines. This latter association is so often made that the propulsive devices in aircraft are called combustors. Similarly, furnaces and boilers, that often involve flames for the production of heat, are combustion devices involving many of the elements of the complete process. Incinerators, too, are commonly associated with combustion of fuel in the form of waste materials. Other common manifestations of coiiibustioii are house, forest, and chemical fires ... 

Jarman and Cihal have made a study of the related IGA problem of knifeline attack (KLA) also associated with the HAZs of welded stainless steels. They considered that there are two manifestations of KLA of similar appearance. One is classical IGA which they refer to as KLA, whilst... 

Thus, whenever the set A has a manifest self-similarity, so that, like the Cantor set, it can be defined by a recursive geometric construction, Dfractal oan be easily calculated from this relation. The Koch Curve, for example, the first three steps in the construction of which are shown in figure 2.2, has a length L which scales as... 

It should be noted that the manifestation of macro- and heteroreticulation is also observed for other carboxylic CP. A similar picture was obtained for weakly alkaline CP based on the derivatives of methacrylamide with HHTT [26]. 

The first main challenge is to prevent persistent and harmful employee conflicts - that is, the balance between diversity and similarity (or organizational norms ) can in some cases lean too far toward diversity. This implies that the differences in perspectives, behaviours and work concepts become dysfunctional and lead to culture clashes (Loden and Rosener, 1991). The manifestation of these involves misunderstandings, feelings of threat... 

Similar experiments were conducted with deuterium. Comparing the results of these experiments with those obtained with protium, a conclusion was made that the ratio of calculated coefficients of surface diffusion of these particles is close to Vz. In other words, this ratio is a manifestation of a usual isotopic shift for diffusivity given by as one might expect assuming that surface diffusion... 

PCP produced electrical seizure activity at 12.8 mg/kg IV, EEG spectra were clearly different from those produced by lower doses in that fast-frequency, high-amplitude EEG waves occurred and resulted in a spectral peak at about 15 Hz. EEG activity from 0 to 35 Hz occurred during seizures in contrast to subseizure doses, which produced EEG with little activity beyond 10 Hz. Generally, these seizures occurred immediately after IV injections and lasted 1 to 3 minutes. Similar spectra were obtained with NsBPCA (12.8 mg/kg), SKF-10,047 (25.6 mg/kg), and even with ketamine despite the absence of overt convulsant activity. Motor manifestations of EEG seizure activity included whole body tremors and vigorous twitches of the face and vibrissae. 

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