Concurrent Actions

The rely condition qualifies the description, saying that it is valid only if the stated condition remains true through the life of the occurrence. If a concurrent action causes it to be false for ary of period of time, then we cannot point to any overlapping period and say, There is an occurrence of supply. (Not according to this description at least there may be other descriptions that define what supply means over such a period.)... 

Figure 4.10 Action multiplicity = 1 bans concurrent actions.

A postcondition therefore means not that the difference between before and after will always be literally what is stated. Instead, it means that if you take into account concurrent actions, the cumulative effect will be what you d calculate from all the postconditions of the actions. So if you compare the till contents at the beginning and the end of the trading day, you should get a balance equaling the sum of all the sales, bankings, robberies, and so on. 

Abstract actions can proceed concurrently with others provided they satisfy concurrency constraints. When specifying essential concurrency, we use rely and guarantee clauses on actions to implicitly constrain what can happen concurrently, or we can explicitly define concurrent actions by multiplicities and other explicit constraints. 

Concurrent actions Any number of members can be borrowing or returning book copies, or reserving book titles at the same time a given book copy can have only one borrow or return involving it at any time. 

Specifying concurrent actions using rely and guarantee is based on the work of Cliff Jones [Jones93],... 

We have investigated the concurrent action of some of the more commonly reported phenolic allelochemicals by testing these compounds at, or below, their inhibition threshold (18-21). Our first experiments showed that a combination of 5 mM each of p-coumaric and ferulic acids reduced grain sorghum Sorghym hicolor (L.) Moench.] germination appreciably more than separate treatments... 

In contrast, oximino enamines were obtained by a concurrent action of oxygen and nitrogen monooxide35 as shown in Scheme 20 for 7V-morpholinocyclohexene. 

In the method of Cori and Lamer, glycogen (or amylopectin) is completely digested by the concurrent action of muscle phosphorylase and amylo-(l 6)-glucosidase. n-Glucose (which arises only from residues attached to C6 of an adjacent residue) and n-glucosyl phosphate (which is obtained from all other residues) are determined, and the branch-point content is calculated from the proportion of D-glucose. Only 10-15 mg. of glycogen is required for each assay the method has been applied to more... 

The phenomenon of the concurrent action of light and air on organic compounds, leading under certain conditions to the formation of substances that are more powerful oxidants than oxygen itself, has interested chemists for a long time. Peroxidic compounds were obtained from alcohols (48-56) and ethers (57-64) through the action of ultraviolet and/or visible light in the presence of O2. It is certain that for the most part these reactions did not reflect the photochemistry of O2-CT complexes but were sensitized by carbonyl compounds and other impurities. This must be especially true for aqueous and neat alcohols since it was practically impossible at the time to ensure the absence of such impurities. 

There is now convincing evidence that glycogen is synthesized by the concurrent action of two transglucosylases these are glycogen-UDP-glucosyl transferase " and a branching enzyme. Phosphorylase, which... 

There is, therefore, no reason to doubt that the concurrent action of glycogen-UDPglucosyl transferase and branching enzyme could provide one pathway for the in vivo synthesis of glycogen. 

The digestion of proteins in the duodenum requires the concurrent action of several proteolytic enzymes, because each is specific for a limited number of side chains. Thus, the zymogens must be switched on at the same... 

The intestinal surface membrane from rats contains both (1 4)-a- and (1 6)-a-D-glucosidase (-glucanase) activities and these enzymes have been given the trivial names of sucrase and isomaltase , respectively. The concurrent action of the sucrase and isomaltase active sites of the hybrid sucrase-isomaltase enzyme complex has been studied on the hexasaccharide (1). Hydro-... 

The concurrent action of sucrose a-D-glucohydrolase and oligo-l,6-D-gluco-sidase active sites of the hybrid oligo-l,6-D-glucosidase-sucrose a-D-glucohydrolase ( sucrose-isomaltase ) from rat intestine on an a-limit dextrin was studied by use of 6 -maltotriosylmaltotriose isolated from the products of controlled action of pullulanase on pullulan (see p. 522). ... 

The case studied here is the simultaneous and concurrent action of two forces on the same point P in the situation called state of equilibrium of forces, a situation that is classically qualified of static, this is to say in the absence of movement and thereby of time. One shall see that this limitation to the static regime is not an absolute requirement for applying the model proposed by the Formal Graph approach. 

As reported by Kanca and co-workers, the enantioselective transesterification polycondensation of racemic AB-type monomers containing a secondary hydroxy group and a methyl ester moiety led to chiral polyesters by iterative tandem catalysis. The concurrent actions of an enantioselective acylation catalyst (such as CALB) and a racemisation catalyst (Ru(Shvo)) resulted in the high conversion of the racemic monomers to enantioenriched polymers. AB-type monomers used were typically methyl 6-hydroxyheptanoate, methyl 8-hydroxynonanoate and methyl 13-hydroxytetradecanoate. The polycondensation at 70 "C in toluene gave a polyester of high yield with a M of around several thousand and an enantiomeric excess higher than 74% [18]. 

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