An approach to the fluctuation mechanism of ecotone

In this paper, the relationship among land productivity, population pressure and the fluctuation mechanism of ecotone is analyzed, taking counties and banners of southeast Inner Mongolia plateau as an example, which is the most fragile part in the farming and husbandry interleaving belt of north China due to its severe desertification degree and low level of economic development. The C v for the total output value of agriculture decreases from southeast to northwest, with the same rule as which the overloading population cumulated distributes, and both indicators have close relation with the high linear coefficient of 0 83. These reveal the fluctuation mechanism for ecotone: fluctuation of the level of economic development is a scientific and practical measure both to weakness degree and to instability of ecotone, because it is a synthesized response to the variation of climate as well as irrational land uses, which reinforce and magnify the fluctuation. In detail, the heavier the population overloading, the severer the grassland reclamation, the stronger the dependence of regional productivity on rainfall, the lower the level of economic development, the rougher the fluctuation of ecotone, but the weaker the PRED system.

Infimum Properties Differ in the Weak Truth-table Degrees and the Turing Degrees

We prove that there are non-recursive r.e.sets A and C with A<T C such that for every set F(?)T A,C∩F≡w(?).

A Weak* Similarity Degree Characterization for Injective von Neumann Algebras

In this note, we show that avon Neumann algebra M is injective if and only if the weak＊ similarity degree d.（M） ≤ 2.