What is Diversity

All chemists engaged in combinatorial chemistry must come to terms with the concept of diversity , although it is not yet possible to give a reliable answer to the question of what diversity is. 

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What is diversity Within this workshop, we have been primarily defining diversity in terms of race and ethnicity. There is also diversity in gender as well as diversity in career paths. Diversity in the chemical workforce should not be framed solely within a discussion of academic achievement as the one and only possible route for a success story. Success stories are also to be found in industry. We should therefore think about the need for diversity in many different directions. We should think about it in a holistic kind of way, if you will pardon a new-age term. It is all related. So, do not try to solve just one diversity problem within a particular setting. Instead think about how solving that problem might fit in within the context of all the other problems. 

As described before, it is due to the vast amount of possible structures that one can never get an adequate sample of chemical space. One question is if the entire chemical space is relevant for finding pharmacologically active compounds and how to predict this for future targets [19]. Another question is how to sample a part of chemical space in a uniform, systematic fashion. Often, the answer is considered to be a diverse selection. However, what is diversity [20] The usual method to describe diversity is to determine Tanimoto distances. These coefficients are calculated by comparing the number of shared and unique molecular fingerprints within a pair of structures. Usually, compounds with Tanimoto >0.85 are considered to be similar. The lower the Tanimoto coefficients in a compound set are, the more structurally diverse the set can be... 

This entire book is about the emergence, nature and cultivation of a new discipline, materials science and engineering. To draw together the strings of this story, it helps to be clear about what a scientific discipline actually is that, in turn, becomes clearer if one looks at the emergence of some earlier disciplines which have had more time to reach a condition of maturity. Comparisons can help in definition we can narrow a vague concept by examining what apparently diverse examples have in common. 

As you pay homage to the diversity of behavior that emerges across the spectrum of all possible representations of all possible systems, you inevitably conclude that (1) there can be no objectively privileged system for which the emergent structures are real, and suc.h that all other structures, for all other derived systems, are less real, and (2) reality, or the emergence and identity of particular sets of objects and their interactions, is wholly dependent on the arbitrary dynamical labels that prescribe a particular system. In short, reality lo.ses its objectivity, and takes on a more tentative, ineffably relative facade. You begin to wonder if the best that you can do to get a hold on objective reality is to look for whatever remains fixed -i.e. what is universal - within the space of all possible representations, all possible rules, and all possible emergent structures. 

For what is an apparently straightforward problem, wavefront sensing has produced a large number of apparently quite different solutions (for example the Shack-Hartmann (Lane and Tallon, 1992), curvature (Roddier, 1988) and pyramid (Ragazzoni, 1996) sensors). Underlying this diversity is the problem... 

Mineralization and immobilization in the rhizosphere are processes that are probably suitable to enable us to estimate ecosystem performance—e.g., productivity, stability, resilience. To properly answer this question, we should understand how differences in plant species may affect below-ground subsystems and what is the functional significance of diversity of. soil organisms. 

Therefore, we see that the development of EEP semiconductor detectors is a challenge that expects knowing of diverse experimental equipment, and, what is more, carrying out some particular investigations. The experimental difficulties, however, are compensated for by the ad-... 

The word cancer covers a diverse array of tumors types that affect a significant number of Americans and are a significant cause of mortality. The term cancer actually refers to more than 100 diseases. What is common to all cancers is the cancerous cell has uncontrolled growth so that it invades tissues and spreads to other parts of the body, called metastasis. In 2005, it is projected that over 1.3 million Americans will be diagnosed with cancer, whereas more than 560,000 Americans will die from the cancer.1 Figure 85-1 reveals cancers by gender, new cases, and deaths. 

The biological activity of a compound can often be affected dramatically by the presence of even a single fluorine substituent that is placed in a particular position within the molecule. There are diverse reasons for this, which have been discussed briefly in the preface and introduction of this book. A few illustrative examples of bioactive compounds containing a single fluorine substituent are given in Fig. 3.1. These include what is probably the first example of enhanced bioactivity due to fluorine substitution, that of the corticosteroid 3-1 below wherein Fried discovered, in 1954, that the enhanced acidity of the fluorohydrin enhanced the activity of the compound.1 Also pictured are the antibacterial (3-fluoro amino acid, FA (3-2), which acts as a suicide substrate enzyme inactivator, and the well-known anti-anthrax drug, CIPRO (3-3). 

In this chapter, we first present a brief overview of the experimental techniques that we and others have used to study torsional motion in S, and D0 (Section II). These are resonant two-photon ionization (R2PI) for S,-S0 spectroscopy and pulsed-field ionization (commonly known as ZEKE-PFI) for D0-S, spectroscopy. In Section HI, we summarize what is known about sixfold methyl rotor barriers in S0, S, and D0, including a brief description of how the absolute conformational preference can be inferred from spectral intensities. Section IV describes the threefold example of o-cholorotoluene in some detail and summarizes what is known about threefold barriers more generally. The sequence of molecules o-fluorotoluene, o-chlorotoluene, and 2-fluoro-6-chlorotoluene shows the effects of ort/io-fluoro and ortho-chloro substituents on the rotor potential. These are approximately additive in S0, S, and D0. Finally, in Section V, we present our ideas about the underlying causes of these diverse barrier heights and conformational preferences, based on analysis of the optimized geometries and electronic wavefunctions from ab initio calculations. 

The status of the study of variation and inheritance of structure in the central nervous system may be summarized as follows. The brain is extremely variable in every character that has been subjected to measurement. Its diversities of structure within the species are of the same general character as are the differences between related species or even between orders of animals. Some of the structural variations have been shown to correlate with functional disturbances. From what is known of the variations in other systems, it may be concluded that the variants which produce pathological symptoms are not discontinuous characters but are the extremes of a normal distribution. Lesser deviations in the same direction, resulting in behavior which is not classed as pathological, are to be expected. 

The nature of this ionic/hydrophilic liquid phase can be quite diverse it can be made by an onium salt (e.g., ammonium or phosphonium), by an ionic liquid (e.g., imidazolium salts), by polyethyleneglycols, and even water. What is required is that the catalyst-philic phase is not miscible with the other phases... 

There are, however, some limitations to this, involving, e.g., limitations of the metabolism of the organism in question. Where nature can sometimes do what is very difficult for the organic chemist, the reverse is also true in some cases, and synthetic organic chemistry may add a level of diversity... 

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