Contract duration/timing

In addition to cost, time is also critical - not least to ensure construction companies do not overrun the agreed contract duration and incur additional costs themselves (Loosemore et a/. 2003). Clients will also consider project duration when awarding their work, and so companies also frequently bid for work with promises of delivery within very short timescales. 

Figure 11.23. Illustration of ion cyclotron orbit during SORI excitation. (A) For one cycle, the ion cyclotron radius will expand (solid line) and contract (dashed Une). (B) For the duration of the SORI excitation, the ion cyclotron radius will expand and contract many times.

With contracts of duration typically varying from 3 to 5 years, it is in most cases impossible at the outset to determine performance factors which can reflect the probably changing asset need with time but typical examples are ... 

Stimulation of the motoneuron releases acetylcholine onto the muscle endplate and results in contraction of the muscle fiber. Contraction and associated electrical events can be produced by intra-arterial injection of ACh close to the muscle. Since skeletal muscle does not possess inherent myogenic tone, the tone of apparently resting muscle is maintained by spontaneous and intermittent release of ACh. The consequences of spontaneous release at the motor endplate of skeletal muscle are small depolarizations from the quantized release of ACh, termed miniature endplate potentials (MEPPs) [15] (seeCh. 10). Decay times for the MEPPs range between l and 2 ms, a duration similar to the mean channel open time seen with ACh stimulation of individual receptor molecules. Stimulation of the motoneuron results in the release of several hundred quanta of ACh. The summation of MEPPs gives rise to a postsynaptic excitatory potential (PSEP),... 

In Vitro Mediator Release. Although no pulmonary effects have been demonstrable in guinea pigs following inhalation of bract extract (104), contraction of isolated guinea pig ileum by extracts (105,106) has been reported. Aqueous extracts of cotton, jute, flax, and hemp cause contractions of isolated guinea pig ileirni or tracheal muscle preparations which are similar in time of onset and duration to those produced by... 

Furthermore, synchronization of contraction is facilitated by gap junctional communication as well as synchronization of electrical activation. The electrical coupling between cardiomyocytes mitigates differences in the membrane potential between these cells, for example in the course of an action potential if both cells repolarize at different timepoints. This results in smaller differences in the repolarization times thereby causing a reduction in the dispersion of the action potential duration. Since increased dispersion is known to make the heart more prone to reentrant arrhythmia, sufficient gap junctional communication can be considered as an endogenous arrhythmia-preventing mechanism. For a detailed discussion of the role of gap junctional communication in the biophysics of cardiac activation as related to anisotropy, nonuniformity and stochastic phenomena, see chapter 1 for a discussion of their role in arrhythmia, see chapter 6, and for a possible pharmacological intervention at the gap junctions for suppression of arrhythmia, refer to chapter 7. 

Caldum channel antagonist activity was determined in isolated rabbit ear artery rings depolarized by a high K+ concentration [7]. The duration of action in vitro (Dw) was determined by means of wash-out experiments. Rabbit ear artery rings were contracted by a submaximal concentration of calcium, and incubated with the tested compounds for 60 min. Subsequently, they were washed with saline solution until the initial contraction was restored. Dw was defined as the time required by the tissue to recover the basal effect elicited by a submaximal concentration of calcium [8], Antihypertensive activity and Dw were determined in chronically implanted spontaneously hypertensive rats (SHR) [9]. 

Phenylephrine and entry 1, 30 and 10p,g/kg, respectively, were introduced into the vena femoralis through a polyethylene cannula. Compared with phenylephrine, the experimental agent exhibited a potency factor 2.73 times greater with regard to the contraction of the urethra and with a duration longer by a factor of 4.3. Moreover, the increase in blood pressure associated with entry 1 was only 1.39 times that of phenylephrine. Testing results are provided in Table 2. 

Most fibers can be classified as slow-twitch (ST) or fast-twitch (FT). The latter have a shorter time to peak tension, shorten faster, and have a shorter relaxation time than the former, and are used for movements requiring high speed or power. ST fibers are used for sustained activity and control of posture. The speed of shortening is related to the ATPase activity of the myosin, while the twitch duration parameters are related to the extent of the SR, and so these two are not directly connected. However, fiber histology and myosin gene expression have some controlling influences in common, so that speed of contraction and twitch duration vary inversely. 

Cold concentrated solutions of caustic alkalis appear to have little effect when contact is short in duration and when rinsing follows immediately. Thus mixed cotton and silk fabrics may be mercerized when the contraction of the cotton gives a crimped effect. Prolonged action of cold concentrated sodium hydroxide causes the fibroin to become dissolved with ultimate breakdown into sodium salts of a amino acids. At the boil quite mildly alkaline solutions will dissolve fibroin rapidly. Lousy silk is formed more readily in the presence of alkali, but some mechanical rough handling is necessary at the same time. 

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