Decision constants

Possible secondary structures of pardaxin (6) were predicted by the Delphi program (12) using decision constants (DHA = -75, DHE = 50) that favor a helices over extended segments and by the Amphi program that identified possible amphipathic a helices and p strands (Guy, unpublish data). Delphi predicted that pardaxin segments 1-8 and 16-25 were a helices and the remainder may be coils or turns. Amphi predicted that segments 1-12 and 13-28 could form amphipathic a helices. 

The automatic choice of decision constants (DC) is the standard feature of the testing procedure by the SPLIT algorithm. In the first prediction loop, preliminary prediction results for tested protein are used for the automatic determination of decision constants for helix (dch), sheet (dee) and coil (dec) conformation (turn or undefined). Each choice of decision constants is made sequentially and independently of previous choices in the following order Constants dch = 0.3, dee = -0.6 and dec = 0 are chosen when predicted helical conformation is... 

Table 3 results compare the importance of different devices used in the SPLIT algorithm. Chosen smoothing procedure is very important, while main filter procedure is next in importance. Subroutines FILTER, CHARGE-BREAK, TURN-BREAK (Methods) and routine for finding maximum preference for the a-helix configuration were all eliminated to examine the importance of the main filter procedure. Automatic choice of decision constants for each tested protein helps to improve the prediction accuracy and the improvement is most obvious when Ajj and Qp parameters are compared in the presence of the decision constants device (first row) and in its absence (fourth row). 

There is an automatic recognition of different folding types of integral membrane proteins and automatic choice of decision constants for each type which improves the prediction accuracy. 

MRP serves as a tool to make production quantity decision. However, MRP assumes deterministic demands subject to changes in different periods. MRP is a push system. The example above assumes a static MRP that has a fixed planning horizon, 6 weeks. In reality an MRP needs to be run each period to manipulate productions decisions. Rolling horizon approach implements only the first-period decision of A -period problem [3]. When using rolling horizon approach, number of periods should be long enough to make the first-period decision constant. 

Ihe allure of methods for calculating free energies and their associated thermod)mai values such as equilibrium constants has resulted in considerable interest in free ene calculations. A number of decisions must be made about the way that the calculatior performed. One obvious choice concerns the simulation method. In principle, eit Monte Carlo or molecular dynamics can be used in practice, molecular dynamics almost always used for systems where there is a significant degree of conformatio flexibility, whereas Monte Carlo can give very good results for small molecules which either rigid or have limited conformational freedom. 

In addition to the drift with time, step changes due to operating decisions, atmospheric changes, or other conditions result in additional time dependence. Not only is there a sudden change due to the actual decision, but also the plant changes due to the time constants. For example. Fig. 30-13 shows measurements with step changes in the operation. 

In these circumstances a decision must be made which of two (or more) kinet-ically equivalent rate terms should be included in the rate equation and the kinetic scheme (It will seldom be justified to include both terms, certainly not on kinetic grounds.) A useful procedure is to evaluate the rate constant using both of the kinetically equivalent forms. Now if one of these constants (for a second-order reaction) is greater than about 10 ° M s-, the corresponding rate term can be rejected. This criterion is based on the theoretical estimate of a diffusion-controlled reaction rate (this is described in Chapter 4). It is not physically reasonable that a chemical rate constant can be larger than the diffusion rate limit. 

During the manufacturing process, if the grafting increases during early stages of the reaction, the phase volume will also increase, but the size of the particles will remain constant [146-148]. Furthermore, reactor choice plays a decisive role. If the continuous stirred tank reactor (CSTR) is used, little grafting takes place and the occlusion is poor and, consequently, the rubber efficiency is poor. However, in processes akin to the discontinuous system(e.g., tower/cascade reactors), the dispersed phase contains a large number of big inclusions. 

Revenues are summed from an initial period thronghont the economic lifetime of the investment. The business decision rule is that an investment is profitable when its net present value is positive. If revenues accrue at a constant rate, continuously and forever, the equation becomes simpler. In the inequality I < R/r, an investment is profitable il aimiial revenue, R, divided by the discount rate, r. 

Even when the time comes to make a purchasing decision, an energy-efficient motor purchase is not a certainty. Sometimes an energy-efficient motor will be the economically efficient choice at other times, not. The capital investment decision is based on the cost in relation to performance, efficiency and reliability. Moreover, the decision depends on the application and the amount of time the motor is in operation. It can be the major component of a product (drill or mixer), or a minor component (computer disk drive) it can be the major component cost of a product (fan), or it can be a minor component cost (stereo tape deck) it can run almost constantly (fan, pump, and machinery), or only a few minutes a day (vacuums and power tools). For example, contractors purchase circular saws almost solely based on performance and reliability. Time is money, and since the saw is operating only a few minutes a day and the contractor is often not responsible for the electricity costs to run the motor, energy efficiency is not a consideration performance and reliability are what matter most. On the other hand, an industrial user, who runs huge electric motors twenty-four hours a day to work pumps, machinery, and ventilation equipment, is very concerned tvitli energy efficiency as well as performance and reliability. 

The values of i calculated from (8) and (8) do not agree very closely, and it would appear, as Weinstein (loc. cit. 1068) remarks, that Although the calculations undoubtedly establish the legitimacy of the system of equations, the great uncertainty in the numerical determination of the decisive magnitudes forms a practical defect which will only be removed by observations over very wide intervals of the variables. Any discrepancy between the results of actual observations of equilibria, and those calculated by means of Nernst s chemical constants, need not, in the present state of uncertainty of the latter, cause any great alarm. Nernst himself apparently regards the constant < >, obtained from vapour-pressure measurements, as the most certain, and the others as more or less tentative. 

Other considerations aside, the use of dilute reagents minimizes effects of nonideality. This allows the use of concentrations in place of activities. Of course, the time scale, the sensitivity of the analytical method at different concentrations, and the use of other reaction components introduce additional considerations. Tied closely to this decision is the choice of solvent. Reaction rates may (or may not) be affected by such variables as polarity, dielectric constant, hydrogen-bonding ability, donor capacity, and viscosity. A change in solvent may change not only the rate but also the mechanism and possibly even the products. One cannot even assume that the net reaction is the... 

Suppose you have two identical PFRs and you want to use them to make as much product as possible. The reaction is pseudo-first-order and the product recovery system requires a minimum conversion of 93.75%. Assume constant density. Do you install the reactors in series or parallel Would it affect your decision if the minimum conversion could be lowered ... 

In series with a constant enthalpy, controlled by entropy changes, steric effects (15), or more particularly, kinetic steric effects (13, 14) and solvent effects (14) may be decisive. 

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