Chemical parsimony

What is called chemical parsimony (stinginess) is applied among termite pheromones. One compound serves as pheromone for a number of species. Moreover, dodecadienol, produced by females at higher concentration, acts as sex pheromone for males (about 0.1 pg cm for trails and about 1 ng as sex pheromone). This dual use also applies to (Z,Z,E)-3,6, 8-dodecatrien-l-ol, which in some Rhinotermitidae acts as trail pheromone, at low concentration, and sex pheromone at higher concentration. 

Carl Scheele was born in 1742 in a part of present-day Germany that was then part of Sweden. Apprenticed to an apothecary at the age of 14, Scheele became fascinated with the properties of the chemical compounds he worked with. After serving his apprenticeship, he became an apothecary s assistant in Stockholm. He must have lived a parsimonious life, because he soon had enough money to buy an apothecary s shop in the town of Koping in central Sweden, where he set up to perform chemical experiments. 

An alternative inclination has been to view the initial chemical act following excitation as a prompt heterolytic bond fission of some one chromium-ligand bond (,2), (15). Both pictures adequately account for the so far not very elaborate data, the second perhaps more in keeping with the principle of scientific parsimony. 

Stingless bees lay chemical trails with mandibular gland constituents which have been identified as normal aliphatic alcohols or monoterpene aldehydes. Trigona spinipes generates a trail with a mixture of 2-heptanol, 2-undecanol, and 2-tridecanol, and it has been possible to successfully lay artificial trails with these alcohols (136). Trail following in workers of Trigona subterranea is released by citral (130), the stereoisomers of which are also utilized as alarm pheromones and defensive compounds. Such pheromonal parsimony appears to be especially typical of eusocial bees and ants. 

Tarr s opinion of these events went unrecorded, if it was ever expressed in words at all. But on July 2 5—even before the order to stop work was passed down—he chose to tell Hueper what Lanza had done to him. When Tarr s activities are examined at a remove of 60 years, his role seems ambiguous yet Hueper recounted in 1955 that he had enjoyed the most harmonious cooperative relations with Mutual Chemical during Tarr s lifetime.35 Hueper s information was incomplete—he was unaware that Mutual had withheld from him in 1946 its knowledge of high cancer rates among its workers— but he knew much of what had happened, and he was parsimonious, to say the least, with praise for industrial managers. His positive evaluation of Tarr can hardly be dismissed. 

The metabolic pattern of extinct ancient organisms can be predicted from the rule of parsimony (Appendix 10). In addition the existence of unique structures with very wide systematic occurrence (Appendix 11) can be explained by the concept of similar receptor structures in the different receptor families sharing affinity to certain chemical entities. 

This is parsimony which would not be in the sense of a synthetic chemist synthesizing a new drug molecule It is not directed towards specificity but serves rather the opposite to obtain a broad-band chemical mace as efficacious as possible against as many targets as possible. This section has shown the enormous versatility of STL structure and the major determinants of their structural diversity. In this light on the outstanding success of STLs as secondary natural products in evolution the next section will focus in more detail on reactivity as the basis of this success, and on particular structure-activity relationships associated therewith. 

The objective of this study is to use the PCA method to classify predictor variables according to their interrelation, and to obtain parsimonious prediction model (i.e., model that depend on as few variables as necessary) for WQI with other physico-chemical and biological data as predictor variables to model the water quality of the Langat river. For this purpose, principal component scores of 23 physico-chemical and biological water quality parameters were generated and selected appropriately as input variables in ANN models for predicting WQI. 

For more details about the relationship between multivariate finite impulse response models and (parsimonious) VARMAX models in chemical process analysis, see e.g. Seppala et al. (2002). 

As a final remark, we wish to pay homage to Murray S. Blum, who just recently passed away and who was one of the first to demonstrate the importance of chemical mediation in the living world. Among other things, Murray brought the notion of parsimony into chemical ecology, along with his smile, which he distributed without parsimony. 

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