Central idea

Modem photochemistry (IR, UV or VIS) is induced by coherent or incoherent radiative excitation processes [4, 5, 6 and 7]. The first step within a photochemical process is of course a preparation step within our conceptual framework, in which time-dependent states are generated that possibly show IVR. In an ideal scenario, energy from a laser would be deposited in a spatially localized, large amplitude vibrational motion of the reacting molecular system, which would then possibly lead to the cleavage of selected chemical bonds. This is basically the central idea behind the concepts for a mode selective chemistry , introduced in the late 1970s [127], and has continuously received much attention [10, 117. 122. 128. 129. 130. 131. 132. 133. 134... 

The central idea underlying measurements of the area of powders with high surface areas is relatively simple. Adsorb a close-packed monolayer on the surface and measure the number A of these molecules adsorbed per unit mass of the material (usually per gram). If the specific area occupied by each molecule is A then the... 

The projector augmented-wave (PAW) DFT method was invented by Blochl to generalize both the pseudopotential and the LAPW DFT teclmiques [M]- PAW, however, provides all-electron one-particle wavefiinctions not accessible with the pseudopotential approach. The central idea of the PAW is to express the all-electron quantities in tenns of a pseudo-wavefiinction (easily expanded in plane waves) tenn that describes mterstitial contributions well, and one-centre corrections expanded in tenns of atom-centred fiinctions, that allow for the recovery of the all-electron quantities. The LAPW method is a special case of the PAW method and the pseudopotential fonnalism is obtained by an approximation. Comparisons of the PAW method to other all-electron methods show an accuracy similar to the FLAPW results and an efficiency comparable to plane wave pseudopotential calculations [, ]. PAW is also fonnulated to carry out DFT dynamics, where the forces on nuclei and wavefiinctions are calculated from the PAW wavefiinctions. (Another all-electron DFT molecular dynamics teclmique using a mixed-basis approach is applied in [84].)... 

A further apphcation of the concept may be found in the patterning of automobile tires to channel residue incident to contact with the road surface away from the automobile tire. Any of these apphcations of the central idea of providing a solution to increase road traction also may be patentable. 

Restraints due to artifacts may, by chance, be completely consistent with the correct structure of the molecule. However, the majority of incorrect restraints will be inconsistent with the correct structural data (i.e., the correct restraints and information from the force field). Inconsistencies in the data produce distortions in the structure and violations in some restraints. Structural consistency is often taken as the final criterion to identify problematic restraints. It is, for example, the central idea in the bound-smoothing part of distance geometry algorithms, and it is intimately related to the way distance data are usually specified The error bounds are set wide enough that all data are geometrically consistent. 

The latter is, except for a couple of terms related to solvent reorganization, the Marcus equation. The central idea is that the activation energy can be decomposed into a component characteristic of the reaction type, the intrinsic activation energy, and a correction due to the reaction energy being different from zero. Similar reactions should have similar intrinsic activation energies, and the Marcus equation obeys both the BEP... 

To improve the latter a number of 0 N) methods have been recently proposed but practically all of them exploit Hamiltonian formalism. However, in Refs. 4,5 the locally self-consistent multiple scattering (LSMS) method based on the real space multiple scattering theory has been outlined, and in Ref. 6 its central idea in the form of the local interaction zone (LIZ) was incorporated into the Green s function technique, leading to the locally self-consistent Green s function method (LSGF). 

The central idea that aided me in undertaking the study of the periodic law of the elements, consists primarily in the absolute distinction between an atom [of e.g. the element carbon] and a simple body [such as diamond or graphite] ([32, p 193]). 

What Are the Key Ideas The central ideas of this chapter are, first, that electrostatic repulsions between electron pairs determine molecular shapes and, second, that chemical bonds can be discussed in terms of two quantum mechanical theories that describe the distribution of electrons in molecules. 

Crystal-field theory (CFT) was constructed as the first theoretical model to account for these spectral differences. Its central idea is simple in the extreme. In free atoms and ions, all electrons, but for our interests particularly the outer or non-core electrons, are subject to three main energetic constraints a) they possess kinetic energy, b) they are attracted to the nucleus and c) they repel one another. (We shall put that a little more exactly, and symbolically, later). Within the environment of other ions, as for example within the lattice of a crystal, those electrons are expected to be subject also to one further constraint. Namely, they will be affected by the non-spherical electric field established by the surrounding ions. That electric field was called the crystalline field , but we now simply call it the crystal field . Since we are almost exclusively concerned with the spectral and other properties of positively charged transition-metal ions surrounded by anions of the lattice, the effect of the crystal field is to repel the electrons. 

Shortly after completing his chapter, one of the authors, Alan Bird, died suddenly and unexpectedly from a heart attack. It is a fitting tribute to Alan that his last published work is in a book that unites plant-and animal-parasitic nematodes within a framework of basic biology encompassing the C. elegans literature. Alan was one of the first scientists to appreciate the power of the C. elegans model to study parasitic nematodes, and also to realize that the conceptual mechanisms of parasitism by nematodes are catholic, no matter what the host. And this central idea was the driving force behind this book. 

Hiickel Molecular-Orbital theory is one of the more useful theoretical guides of the pratising chemist. The central idea is that in certain molecules it is... 

To introduce temperature we use the thermofield dynamics (TFD) formalism (Takahashi et.al., 1996 Das, 1997). TFD is a real time finite-temperature field theory. In TFD the central idea is the doubling of the Hilbert space of states. The operators on this doubled space... 

It must be realized that urban wastewater management is difficult to cope with in a sustainable way, because the entire idea is to use resources and pollute them In spite of this, the sustainable development of the urban infrastructure must be seriously considered, particularly because the centralized idea behind the urban water cycle, without doubt, will exist for an unknown future. 

Bechhofer F., 1974. Current approaches to empirical research some central ideas, Routledge, London. 

A broader and more detailed evaluation can be done by performing a Life Cycle Analysis (LCA). The central idea of a LCA is that the environmental effects during the entire life cycle of a process are quantified. These environmental effects are caused by the use of fossil fuels for heating and production of electricity, the use of non-renewable raw materials for the production of materials and chemicals, and the emissions of pollutants to air, water and soil. These environmental effects can be subdivided further in various levels of detail. The five major effects mentioned are derived from the more general effects considered in the framework of the LCA. Based on the environmental sustainability of each of the complete treatment scenarios considered as technically feasible, a ranking according environmental... 

This approach, also often called the stockholder scheme, was introduced in 1977 by Hirshfeld [22]. The central idea of the Hirshfeld method originates in x-ray crystallography. It proposes to divide the electron density among the atoms in a molecule, guided by a promolecular density. More precisely, once a molecular geometry is known, a promolecular density p°(r) is composed by simply summing the density of each atom A (denoted p°A(r)) in an isolated state ... 

No attempt is made to review the literature — references are only made to existing techniques as and when they impinge on the central ideas of this exposition. Occasionally we are critical of some of the established schemes this is not, of course, to belittle the importance of the ideas of the pioneers in this field but rather to question the continued uncritical use of these ideas. 

Lindenberg (6) has proposed a novel and formally neat scheme for the non-empir-ical calculation of the bonding parameters (the P s) involved in the approximate MO theory of conjugated 7r systems. This elegant piece of work provides a good example of the effect of correct consistency requirements and so we evaluate it carefully. The central idea is to use the formal relationship... 

Neither the equilibrium (57) nor the complexation (58) are new what is new is their combination here in the form used for the A1C13 + IB system. The central idea is that only the ions due to the BIE, which are present at the moment of mixing can be effective initiators, because the subsequent regeneration of ions by the BIE is far too slow to affect the very fast polymerisation. 

On its face, Gentleman s Agreement is unequivocal in its erasure of Jewish racial difference indeed, whatever statement the novel seeks to make about Jewishness, and, finally, about justice, derives entirely from the central idea of interchangeability. Phil Green can experience anti-Semitism firsthand because he can pass as a Jew and he can pass because, at bottom, there is no difference between Jews and Gentiles. (This, in turn, is what is so absurd about anti-Semitism, Hobson will have us conclude. What does it mean that a non-Jew can be the victim of Jew-hatred )... 

How far the significance of these animal experiments can be translated into human terms is a question we will not discuss here. It is worthy of note, however, that these experiments give strong corroboration of the central ideas of this chapter, namely, (1) each human individual has quantitatively a distinctive pattern of nutritional needs, (2) from individual to individual, specific needs may vary several-fold, and (3) important deficiencies may exist which have not been discoverable clinically by observing acute outward symptoms. 

The central idea of PCA is to reduce the dimensionality of a data set that may consist of a large number of interrelated variables while retaining as much as possible of the variation present in the data set [317-320]. 

The central idea of contrast variation is shown in Fig. 5. The dissolved object is depicted as an assembly of scattering units with different scattering power. The entire object occupies a volume in the system depicted by the shaded area in Fig. 5, left-hand side. The local scattering length density r) is rendered as a product of the shape function T (f) and the local scattering length density inside the object ... 

Interestingly, the amorphous regions within the spherulite confer some flexibility onto the material while crystalline platelets give the material strength, just as in the case with largely amorphous materials. This theme of amorphous flexibility and crystalline strength (and brittleness) is a central idea in polymer structure-property relationships. 

Several points are worth emphasizing (i) single observables should not be used to assess overall sampling quality, (ii) The central ideas in single-observable... 

Among all the details we have seen so far in this chapter, there are two central ideas that we hope you will remember long after putting this book down ... 

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