Intuitions empirical

This paper illustrates how the principle of vinylogy may serve to direct attention to possible structural similarities in a large number of diverse structures of herbicides with similar activity and mode of action which might otherwise appear unlikely. Structural information such as this on various classes of PS II herbicides in conjunction with intuitive-empirical or computer oriented approaches should facilitate the design of new inhibitors. 

Intuitive, empirical grasp of a concept was memorably expressed by Associate Justice Potter Stewart in the US Supreme Court decision in Jacobellis versus Ohio [12] Perhaps I could never succeed in intelligibly [defining it]. But I know it when I see it. ... 

A basic theme throughout this book is that the long-chain character of polymers is what makes them different from their low molecular weight counterparts. Although this notion was implied in several aspects of the discussion of the shear dependence of viscosity, it never emerged explicitly as a variable to be investi-tated. It makes sense to us intuitively that longer chains should experience higher resistance to flow. Our next task is to examine this expectation quantitatively, first from an empirical viewpoint and then in terms of a model for molecular motion. 

It is obvious, fipom some of the series of substituents in Table 7-11, that the steric constant reflects intuitive notions of group size, and Taft " pointed out close parallels with van der Waals radii. For asymmetrical groups a single van der Waals radius cannot be defined, and the situation is complicated by conformational flexibility. Nevertheless, empirical relationships can be established, and Kutter and Hansch gave Eq. (7-55),... 

As the most notable contribution of ab initio studies, it was revealed that the different modes of molecular deformation (i.e. bond stretching, valence angle bending and internal rotation) are excited simultaneously and not sequentially at different levels of stress. Intuitive arguments, implied by molecular mechanics and other semi-empirical procedures, lead to the erroneous assumption that the relative extent of deformation under stress of covalent bonds, valence angles and internal rotation angles (Ar A0 AO) should be inversely proportional to the relative stiffness of the deformation modes which, for a typical polyolefin, are 100 10 1 [15]. A completly different picture emerged from the Hartree-Fock calculations where the determined values of Ar A0 AO actually vary in the ratio of 1 2.4 9 [91]. 

From the Arrhenius form of Eq. (70) it is intuitively expected that the rate constant for chain scission kc should increase exponentially with the temperature as with any thermal activation process. It is practically impossible to change the experimental temperature without affecting at the same time the medium viscosity. The measured scission rate is necessarily the result of these two combined effects to single out the role of temperature, kc must be corrected for the variation in solvent viscosity according to some known relationship, established either empirically or theoretically. 

Although the first mechanism is intuitively, and for reasons of simplicity, preferred to the second one, there is no experimental evidence for excluding the latter. Theoretical evidence for preferring the former mechanism stems from a study by Jansen and Ros (1969), who performed non-empirical calculations on several configurations of a model system, viz. protonated carbon monoxide. They found that the linear +... 

Michelspacher s title-page is not, in fact, a monument to empirical learning, but takes the form of a memento mori. Far from applauding the new Renaissance humanism, on the contrary, he employs the science of anatomy as a metaphor to demonstrate the futility of rational knowledge in the face of death and decay.The prospect of immortality is available only to those who seek an intuitive Gnosis, a divine epiphany concerning God s work in Nature. 

A sample is representative of a neighborhood measured by the range of correlation. For example, a soil sample could represent a circular area in the field centered at the sample site with a radius less than or equal to the zone of influence. This has always been intuitively obvious to the environmental scientist but now can be described statistically. The zone of influence is defined by the theoretical semi-variogram and is easily estimated from an empirical semi-variogram. 

The transition of empirical alchemy in 18th century Europe to scientific chemistry allowed the discovery of more and more new elements through the thirst for knowledge, intuition, patience, and even luck. Known materials such as gold, silver, copper, iron, and lead were "suspected" to be elements relatively early. Despite all the best efforts, these materials could not be broken down into further components, and hence their being elements was consistent with the then generally recognized definition of John Dalton, which was also staunchly supported by Antoine de Lavoisier. 

Modeling relaxation-influenced processes has been the subject of much theoretical work, which provides valuable insight into the physical process of solvent sorption [119], But these models are too complex to be useful in correlating data. However, in cases where the transport exponent is 0.5, it is simple to apply a diffusion analysis to the data. Such an analysis can usually fit such data well with a single parameter and provides dimensional scaling directly, plus the rate constant—the diffusion coefficient—has more intuitive significance than an empirical parameter like k. 

Often solutions have been found empirically, by trial and error. Acceptable solutions can be found, and gifted planners or regulators often develop good intuitive abilities, also taking into account socio-economic factors. However, the linear approach that often works properly for tame problems usually ends in a fiasco when tackling wicked problems. 

The data collected are subjected to Fourier transformation yielding a peak at the frequency of each sine wave component in the EXAFS. The sine wave frequencies are proportional to the absorber-scatterer (a-s) distance /7IS. Each peak in the display represents a particular shell of atoms. To answer the question of how many of what kind of atom, one must do curve fitting. This requires a reliance on chemical intuition, experience, and adherence to reasonable chemical bond distances expected for the molecule under study. In practice, two methods are used to determine what the back-scattered EXAFS data for a given system should look like. The first, an empirical method, compares the unknown system to known models the second, a theoretical method, calculates the expected behavior of the a-s pair. The empirical method depends on having information on a suitable model, whereas the theoretical method is dependent on having good wave function descriptions of both absorber and scatterer. 

The basic strategy in using taxometric procedures is to presume a taxon— for example, depression. Next, we are required to conjecture the presumed taxon s indicators—sadness, anhedonia, and suicidality. Presume and conjecture based on what Clinical experience, intuition, past theory and research. .. it really does not matter. The presuming and conjecturing take place in what Popper (1959) called the context of discovery, where ideas, theories, and hypotheses are developed from any source. The empirical evaluation of these ideas, however, takes place in Popper s context of justification when the question is a taxometric one, the context of justification involves taxometric analyses. 

When the experimental values of I and A are known, one can determine through these expressions the values of /a and tj. Since for atoms and molecules, the trends shown by these values of /a and tj are, in general, in line with those provided by several empirical scales constructed intuitively by chemists, the identification of these global DFT descriptors with their associated chemical concepts is strengthened. In other words, the quantity (I+A)/2 shows, in general, the same behavior as that of the electronegativity concept, while the quantity (I—A) shows, also in general, the same behavior as that of the chemical hardness concept. 

For the moment estimates, we have seen that the composition PDF, /, (delta functions (i.e., the empirical PDF in (6.210)). However, it should be intuitively apparent that this representation is unsatisfactory for understanding the behavior of fyiir) as a function of fj. In practice, the delta-function representation is replaced by a histogram using finite-sized bins in composition space (see Fig. 6.5). The histogram h, (k) for the /ctli cell in composition space is defined by... 

From the values of T,M and B calculated in this way we may note that for both iron and cobalt M 0.68 T and that B 0.5 T. The latter approximation is intuitively consistent with the observations22 of bridge-terminal exchange of coordinated CO. If we now assume that these empirical approximations apply to other polynuclear carbonyls, it is possible to extract the T and M- values for metals other than iron and cobalt, despite the limited AHo data which are available. 

Up until this point, the contribution of the aforementioned workers could be characterized as the formulation of purely empirical rules based upon consideration of some, but not all, experimental evidence. The rules of Wolfe and collaborators were devoid of any theoretical basis and, thus, could never do anything more than act as basis for extrapolation from known experimental data. Thus, the variation of the anomeric effect as a function of halogen substituent alluded to before never attracted the attention of these authors simply because their rules were founded on an intuitive concept of bond polarity which deceptively seemed to be consistent with the great majority of the experimental facts encompassed by the three rules as stated. 

The use of molecular electrostatic potentials calculated from the wave function of ligands, as has been recently suggested 50—54) seems to present a less ambiguous alternative to the more empirical approach described above. This potential can either be calculated exactly for each point of interest according to Eq. (3), or it is approximated by a suitable distribution of point charges choosen either by intuitive guess or by a less arbitrary method like the one of Hall 182>. 

Kitaigorodskii s realization of the complementary packing of molecules was not intuition he arrived at this principle by empirical investigation. 

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