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We present two constructions of infinite words with a complexity function that grows faster than any polynomial, but slower than any exponential. The first one is rather simple but produces a word which is not uniformly recurrent. The second construction, more involved, produces uniformly recurrent words and allows to choose the growth of the complexity function in a large family.

Action selection in the artificial fish is controlled by its behavior system. The behavior system consists of the habits and mental state of the fish, an intention generator and a set of behavior routines (Fig. 7.1). The behavior system runs continuously within the fish’s simulation loop. At each time stepthe intention generator issues an intention based on the fish’s habits, mental state, and incoming sensory information. It then chooses and executes a behavior routine which in turn selects and runs the appropriate motor controllers. It is important to note that the behavior routines are incremental by design. Their job is to get the artificial fish one stepclo ser to fulfilling its intention during the current time step. Moreover, at any given moment in time, there is only one intention or one active behavior in the artificial fish’s behavior system. This hypothesis is commonly made by ethologists when analyzing the behavior of fishes, birds and four-legged animals of or below intermediate complexity (e.g. dogs, cats) [94, 16].

The purpose of the meeting was to exchange information on spheroid culture methods and to review the role of spheroids in cancer research. Techniques and results presented at this meeting suggested many areas of promising research applications using the multicellular spheroid tumor model system to better understand certain aspects of basic tumor biology and responses to different agents with therapeutic potential. Multicellular spheroids provide a system of intermediate complexity between standard two-dimensional culture systems and tumors in vivo and, when applied in experiments in conjunction with studies at other levels of complexity in the other systems, can produce important insight in a variety of areas of tumor biology. Accurate interpretation of results from experiments using multicellular spheroids requires detailed characterization of the particular spheroid culture system being used. Furthermore, care must be exercised to avoid generalizations from the study of only one or a few spheroid systems, since significant differences among different types of spheroid cells have been reported, as is often the case for tumors in vivo. As with any model system, it is important to be continually aware of its strengths and its limitations.