Here we describe the establishment and prediction utilities for a novel nine-amino-acid transactivation domain, 9aa TAD, that is common to the transactivation domains of a large number of yeast and animal transcription factors. We show that the 9aa TAD motif is required for the function of the transactivation domain of Gal4 and the related transcription factors Oaf1 and Pip2. The 9aa TAD possesses an autonomous transactivation activity in yeast and mammalian cells. Using sequence alignment and experimental data we derived a pattern that can be used for 9aa TAD prediction. The pattern allows the identification of 9aa TAD in other Gal4 family members or unrelated yeast, animal, and viral transcription factors. Thus, the 9aa TAD represents the smallest known denominator for a broad range of transcription factors. The wide occurrence of the 9aa TAD suggests that this domain mediates conserved interactions with general transcriptional cofactors. A computational search for the 9aa TAD is available online from National EMBnet-Node Austria at http://www.at.embnet.org/toolbox/9aatad/.

In this paper, we evaluate the uniqueness of several information-theoretic measures for graphs based on so-called information functionals and compare the results with other information indices and non-information-theoretic measures such as the well-known Balaban index. We show that, by employing an information functional based on degree-degree associations, the resulting information index outperforms the Balaban index tremendously. These results have been obtained by using nearly 12 million exhaustively generated, non-isomorphic and unweighted graphs. Also, we obtain deeper insights on these and other topological descriptors when exploring their uniqueness by using exhaustively generated sets of alkane trees representing connected and acyclic graphs in which the degree of a vertex is at most four.

The wavelength dependence of the extinction coefficient in fog and haze is investigated using Mie single scattering theory. It is shown that the effective radius of drop size distribution determines the slope of the log-log dependence of the extinction on wavelengths in the interval between 0.2 and 2 microns. The relation between the atmospheric visibility and the effective radius is derived from the empirical relationship of liquid water content and extinction. Based on these results, the model of the relationship between visibility and the extinction coefficient with different effective radii for fog and for haze conditions is proposed.

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