Biology-based theories

Equation 4.9 has been extensively applied to study the mechanisms of electrophilic (e.g., protonation) reactions, drug-nucleic acid interactions, receptor-site selectivities of pain blockers as well as various other kinds of biological activities of molecules in relation to their structure. Indeed, the ESP has been hailed as the most significant discovery in quantum biochemistry in the last three decades. The ESP also occurs in density-based theories of electronic structure and dynamics of atoms, molecules, and solids. Note, however, that Equation 4.9 appears to imply that p(r) of the system remains unchanged due to the approach of a unit positive charge in this sense, the interaction energy calculated from V(r) is correct only to first order in perturbation theory. However, this is not a serious limitation since using the correct p(r) in Equation 4.9 will improve the results. 

Clearly, these models aU have merit in helping to tease out complex factors that can contribute to the development of depression. These psychological causes also very likely influence much of what goes on in the so-called biologic depressions. However, the focus of this section is limited to a discussion of current theories of biological causation—causes that either imderlie or contribute to the development of the biologic-based depressions listed above. 

Bromek et al. have presented a polychromatic selective polarization inversion (PC-SPI) as an alternative for the application of NMR to large biological molecules. Theory indicate that PC-SPI has the potential for more efficient polarization transfer under conditions of rapid transverse relaxation compared to J coupling- and cross-correlated relaxation-based transfers. They demonstrate these improvements by measuring chemical shift correlation... 

Zuckerman, M. (1983). A biological theory of sensation seeking,. In Biological bases of... 

A key assumption of behavior-based theory is that behavior (desirable and undesirable) is learned and can be changed by providing people with new learning experiences. Diverse cultural, social, environmental, and biological factors interact to influence our readiness to learn behaviors. These factors also support or hinder behaviors once they are learned. We do not understand exactly how the particulars work—diverse factors interacting to influence behaviors for each individual. However, basic ways to develop behavioral patterns have been researched, and it is possible to identify principles behind learning and maintaining human behavior. 

A common use of statistics in structural biology is as a tool for deriving predictive distributions of strucmral parameters based on sequence. The simplest of these are predictions of secondary structure and side-chain surface accessibility. Various algorithms that can learn from data and then make predictions have been used to predict secondary structure and surface accessibility, including ordinary statistics [79], infonnation theory [80], neural networks [81-86], and Bayesian methods [87-89]. A disadvantage of some neural network methods is that the parameters of the network sometimes have no physical meaning and are difficult to interpret. 

In the 1950s, biologists (notably Francis Crick and James Watson) discovered the molecular basis for information coding in DNA and established that the workings of cells were molecular machines tvith understandable structure and function. Mathematician John von Neuman developed a mathematical theory of self-reproducing machines based on the biological theories. 

Early theories of the biological effects of ethanol were based on alterations of lipids in biomembranes (Goldstein et al. 1983 Seeman 1972). Such a nonspecific mechanism provided little guidance for the development of therapeu-... 

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