The colony morphology varies a great deal with the nutrient concentration and the surface moisture of agar plates, including a DLA type, dense branching morphology, a round type, and fast spreading without any openings. Repulsion between two neighboring colonies is observed in the DLA and dense branching morphologies only, suggesting that these growths may be strongly influenced by the concentration field of nutrient. Local growth mechanism characterized by an organism itself is also considered to affect its colony formation. When the agar plate is covered with a thin layer of glycerol, the colony morphology of our strain becomes thoroughly round. This may come from some physical factor such as surface tension of glycerol.
Computer simulations are essential to develop the insight into dynamics of percolating nets.
These have become possible with the advent of array-processing supercomputers, and with the use of a numerical method that does not require diagonalization. It is shown that this wave number behavior cannot be explained by the effective medium theory or using average wave functions. We are concerned with the problem of predicting water flows of the Kusu river system in Kyushu, in the southern part of Japan, which interconnects several multi-reservoir power systems. In particular, we are interested in predicting the residual inflows into the reservoirs. The difficulty with this problem arises from the lack of a sufficient number of observation points as well as a large error in measurements.