Call feature definition

The Accelrys implementation of pharmacophore fingerprint descriptors is called 3D Keys. This application is based on standard Catalyst feature definitions and is a part of the Cerius2 software package [7]. 

Whenever an economic evaluation is undertaken, a corresponding problem definition should be provided as the basis on which the evaluation is made. This definition, sometimes called an economic scope, should clearly differentiate between specifications that have actually been selected and features that have been assumed for the evaluation. In a comparison of alternatives, all of the assumptions, data, and conditions must be consistent, reaUstic, and devoid of bias. 

Figure 3-8 is a plot of Ca, Cb, Cq, and Cd for a hypothetical system of the Scheme X type. An interesting feature is the time delay after the start of the reaction before the final product, D, appears in significant concentrations. This delay in product appearance is called an induction period or lagtime. In order to observe an induction period it is only necessary that the system include several relatively stable intermediates, so that the bulk of the material balance is temporarily stored in these prior forms. An experimental measurement of the induction period requires an arbitrary definition of its length. 

As surface area and pore structure are properties of key importance for any catalyst or support material, we will first describe how these properties can be measured. First, it is useful to draw a clear borderline between roughness and porosity. If most features on a surface are deeper than they are wide, then we call the surface porous (Fig. 5.16). Although it is convenient to think about pores in terms of hollow cylinders, one should realize that pores may have all kinds of shapes. The pore system of zeolites consists of microporous channels and cages, whereas the pores of a silica gel support are formed by the interstices between spheres. Alumina and carbon black, on the other hand, have platelet structures, resulting in slit-shaped pores. All support materials may contain micro, meso and macropores (see text box for definitions). 

There are some comments on this definition we should make. It by no means reflects all possible features of procedures and calls in "real" programming languages. We have deliberately chosen only to reflect features essential to the notion of recursion and to adopt conventions and restrictions that make other concepts as simple as possible. 

Crystalline forms presenting large amounts of disorder of the kind (ii) or (iii) are generally called mesomorphic modifications (Section 3.6), in analogy with the ordered liquids (smectic and nematic). In these cases the lack of periodicities in one or two dimensions (e.g., along the chain axes or along the directions normal to the chain axes) prevents the definition of a unit cell. Typical features in the X-ray diffraction patterns of mesomorphic forms are diffuse halos on the equator or on the layer lines depending on the kind of disorder present. 

The vehicle for a framework is a generic, or template, form of package. Inside the template, some types and their features can be defined using placeholder names. Looking at its definition in the library, we find that the Observation template has two type placeholders Subject and Observer we have imported that package, substituting Stock and Meter. The sustituted definition becomes part of the model. In other words, whatever attributes and operations are defined for Subject within the template s definition are now defined for Stock. Other names can be substituted, too. The template uses an attribute called value for the aspect of the Subject that we want observed so we substitute it for the Stock s level. 

Wavefunctions of electrons in atoms are called atomic orbitals. The name was chosen to suggest something less definite than an orbit of an electron around a nucleus and to take into account the wave nature of the electron. The mathematical expressions for atomic orbitals—which are obtained as solutions of the Schrodinger equation—are more complicated than the sine functions for the particle in a box, but their essential features are quite simple. Moreover, we must never lose sight of their interpretation, that the square of a wavefunction tells us the probability density of an electron at each point. To visualize this probability density, we can think of a cloud centered on the nucleus. The density of the cloud at each point represents the probability of finding an electron there. Denser regions of the cloud therefore represent locations where the electron is more likely to be found. 

In a collision process, it is the relative position of the atoms that matters, not the absolute positions, when external fields are excluded, and the potential energy E will depend on the distances between atoms rather than on the absolute positions. It will therefore be natural to change from absolute Cartesian position coordinates to a set that describes the overall motion of the system (e.g., the center-of-mass motion for the entire system) and the relative motions of the atoms in a laboratory fixed coordinate system. This can be done in many ways as described in Appendix D, but often the so-called Jacobi coordinates are chosen in reactive scattering calculations because they are convenient to use. The details about their definition are described in Appendix D. The salient feature of these coordinates is that the kinetic energy remains diagonal in the momenta conjugated to the Jacobi coordinates, as it is when absolute position coordinates are used. 

Regarding the correct terminology, there are several references and examples of the term molecular wire . In some cases, it describes a system with a very specific behavior. In others, it simply refers to the structural features of the molecule under consideration. Thus, finding a clear definition is a rather difficult task. In 1998 an attempt was made by Emberly and Kirczenow [1] and a molecular wire has been defined as a molecule between two reservoirs of electrons . Nitzan and Ratner, on the other hand, called it a molecule that conducts electrical current between two electrodes [2], Most appropriate with respect to the topic of this thesis, we should stick to a rather restricted definition by Wasielewski, which classifies a molecular wire as a device that conducts in a regime, wherein the distance dependence (of electron transfer) may be very weak [3]. 

The quantitative structure-activity relationship (QSAR) model is by definition a model. Any model, such as animal model (also called in vivo) or in vitro model, is a system that applies to a specific situation, and thus, it is useful to study, evaluate, or assess a more complex system, which cannot be used experimentally for investigation. Thus, any model is a simplification of the target object of the study, and the model is useful for this or not depending on its purpose. It is also possible to imagine a series of models, each addressing one or more features of the more complex system. 

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