In order to make progress on Intelligent Tutoring in ill-defined domains it is helpful to start with a definition. In this paper we consider the existing definitions and select one for the basis of our discussion. We then summarize some of the more salient characteristics of ill-defined domains from a tutoring standpoint and some human and ITS strategies that have been employed to cope with the...

A key decision in research is whether to try out new ideas or build on more established ideas. In this paper, we evaluate which type of work is more likely to spur further invention. When recent advances create superior opportunities for invention, their adoption as research inputs in the invention process promotes technological progress. The gains from pursuing such innovative research paths m...

Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we e...

Most flowers display distinct colour patterns comprising two different areas. The peripheral large-area component of floral colour patterns attracts flower visitors from some distance and the central small-area component guides flower visitors towards landing sites. Whereas the peripheral colour is largely variable among species, the central colour, produced mostly by anthers and pollen or poll...

Circumnutation, the helical movement of growing organ tips, is ubiquitous in land plants. The mechanisms underlying circumnutation have been debated since Darwin's time. Experiments in space and mutant analyses have revealed that internal oscillatory (tropism-independent) movement and gravitropic response are involved in circumnutation. Female flower buds of tape grass (Vallisneria asiatica var...

A new species of Moraceae is described, illustrated and compared to its close morphological relatives. Dorstenia triseriata presents similarities with Dorstenia turnerifolia but distinguished by size of peduncle, diameter of receptacle, number of bract rows, color of marginal bracts, and by an indistinct fringe on inflorescence. A conservation assessment based on IUCN criteria determines the ne...

Kinesins and myosins are molecular motors that move on microtubules and actin filaments, respectively. These motor proteins are involved in a variety of cellular processes such as intracellular transport, spindle formation and chromosome segregation in eukaryotes (Langford, 1995; Hirokawa, 1998). Although kinesins and myosins hydrolyze ATP to generate force for their movement on cytoskeletal fi...

During grain filling in C3 cereals, the shoot (particularly the flag leaf) and the ear are believed to play major roles as sources of assimilates. However, both the cost and the intrusive nature of most of the methodologies available to investigate this have prevented conclusive results being obtained. This study compared the carbon isotope composition (δ(13)C) in its natural abundance in matur...