The Au Sable and Manistee rivers are among the most prestigious trout streams in Michigan. Much of their fame comes from fishing success in the middle and lower sections of the rivers but little has been reported about the upper sections. This report will focus on the upper sections of these two rivers.
These wooded upper regions are largely uninhabited. Soils of the area are comprised mainly of sand and gravel (Burgis 1977; Coopes 1974), which lead to a high degree of water infiltration into the water table. This provides a stable stream discharge, even during the summer months, which is an important factor in maintaining conditions suitable for the fine trout populations that dominate these rivers (Benson 1953b).
Stock market plays a very crucial role in assessing economic conditions of any country through improved stock returns usually signified by higher profit to firms. This consequently engenders economic growth and vice versa. Basically stock exchange market serves as a channel through which surplus funds are moved from Lender-Savers to Borrower-Spenders who have shortages of funds (Mishkin 2000). Based on this premise, volatility in stock prices can significantly affect the performance of the financial sector as well as the entire economy.
Compared to temporal logics, modal logics of space have received very little attention. I can see two reasons for this. First, temporal logic has its roots in the semantics of natural language; here, the notion of tense naturally leads to an extension of classical logics with temporal modal operators. In most familiar languages spatial concepts seem to play a less pervasive role, notwithstanding the many expressions that could be interpreted as spatial modalities. Also, the development of temporal logic has been boosted by concerns from computer science, in the context of program specification and verification. Here temporal properties are of greater interest than spatial ones.
A second reason is perhaps that it is more evident which ontologies to employ when formalizing the notion of time; apart from some notable exceptions, the standard temporal structure consists of a set of time points together with some kind of ordering of these points. When devising a formal model of space we seem to be faced with a far greater choice. Even if we decide to restrict ourselves to points as spatial objects, there are a great number of interesting relations to consider, such as nearness, collinearity, betweenness or equidistance. But also, the restriction to points as the sole entities of the mathematical model is more debatable than in the temporal case. For, space is inhabited by various kinds of things, such as lines, spheres, planes, poyhedra, etc.
