Character hypotheses

Stagnant debates in contemporary systematics will remain so if systematics does not solve its basic problem. Ever more and faster algorithms can be devised to generate hypotheses of relationships and ever more statistical measures can be used to place confidence limits on those hypotheses. These do not, however, solve the basic problem of systematics, which is the nature of character hypotheses, and the problem of their critical discussion. 

Reversible formation of ionic intermediates in halogenated solvents has been suggested to be due to the weakly nucleophilic character of the counteranion, the tribromide ion, which should dissociate into nucleophilic bromide and free bromine before reacting with the bromonium ion (refs. 11,25,26). In order to check this hypothesis the product distribution of the c/s-stilbene bromination in chloroform was investigated (ref. 27). In the latter solvent the formation constant of Br3 is considerably lower than in DCE, Kf = 2.77 (0.13) x 10 against > 2 x 107 M 1. (ref. 28). As a consequence, at 10 3 M [Br2] relevant amounts of bromide ions are present as counteranion of the bromonium intermediate. Nevertheless, the same trend for the isomerization of cis- to rran -stilbene, as well as an increase of... 

When the concentration profile is fully developed, the mass-transfer rate becomes independent of the transfer length. Spalding (S20a) has given a theory of turbulent convective transfer based on the hypothesis that profiles of velocity, total (molecular plus eddy) viscosity, and total diffusivity possess a universal character. In that case the transfer rate k + can be written in terms of a single universal function of the transfer length L and fluid properties (expressed as a molecular and a turbulent Schmidt number) ... 

In the first stage of the LCA analysis, it is necessary to define the objective and the scope of the paper before the actual start [35]. The study goal and scope definition determine the next procedure character and the circumstances in which the study outputs are valid [32]. [36] requires to establish a study goal and scope while the study scope means to determine the product system, the functional unit and system boundaries, to determine allocation rules, the assessment methodology, hypothesis and limits and data quality. 

---