Repeat-loop

At time equals zero the source is a logic zero. It remains at zero for 1 ms and then changes to a one. It remains a one for 2 ms and then changes to a zero. It remains a zero for 0.5 ms and then changes to a one. It remains a one for 1.5 ms and then changes to a zero. It remains a zero for 4 ms and then changes to a one. It remains at one for the remainder of the simulation. REPEATED LOOPS... 

Finally, we redraw Figure 4.44 for exactly the same parameters, except that we use LeA = 0.11. The trajectory from the same initial value o = (xa(0), xb o), y(o)) = (0.1, 0.1, 0.5) as in Figure 4.44 now goes through one high-temperature loop similar to the infinitely repeated loop in Figure 4.46, but then it spirals around the unique steady state in four and a half loops during 1,200 time units, and it will ultimately settle at the steady state. ... 

Repeat Loop Supported Repeat expression has to be a constant. 

The system being described in Figure 2-3 is a Kalman filter, a realtime controller consisting of several loops implementing matrix multiplication and other operations. The input to the system is the y array, and the output is the v array. First to be described are the carriers that will take part in the computation. Second, the procedures that specify the actions on the variables are listed. In this case, there is only one procedure (filt) consisting of several nested, labeled blocks and repeat loops. The "Imain)" qualifier indicates that filt is the starting point for execution. A quote mark (") indicates a hexadecimal constant, labeled blocks are named with a colon-equal ( =), and the is the binary concatenation operator. 

Events that are created in a loop track automatically repeat (loop) when the event extends beyond the length of the original media file. A small notch in the top and bottom of the looped event divides each repetition (see Figure 2.13). 

Right-click the Marker bar to insert a region. Regions are identified by two green markers. The Loop Region (visible in the lower image) is dark blue and is used to repeatedly loop project playback. 

The result of the t-fold vector-matrix multiplication D M Y is a vector of length I S . The component indexed by x G S indicates the probability that state X is reached after the initial random choice followed by t local search steps. Therefore, the success probability , the probability of reaching a solution within one run of the REPEAT-loop, is given by... 

If we could calculate or estimate p (which is quite difficult), then an appropriate number of restarts (number of REPEAT-loops) would be cjp for some constant c. This is so, since the probability of missing a solution in each of the cjp trials is... 

An additional feature of the code is the possible use of the BD time step approach for the first time increment with the repeat loop on line 204. This is needed to start an initial value problem for which some time derivative information is unknown. Finally a feature of the code is the ability to force the use of the BD algorithm for all time increments by setting the bd parameter to some value other than false , by the statement getfenv(pdelstp2felt).bd=true for example. This is primarily for comparison purposes and except for such comparisons it is recommended that the TP algorithm be used for all times except the initial time interval. 

Peiformance. Depending on the application, accuracy, repeatability, or perhaps some other measure of performance is appropriate. Where closed loop control is contemplated, speed of response must be included. 

Another view is given in Figure 3.1.2 (Berty 1979), to understand the inner workings of recycle reactors. Here the recycle reactor is represented as an ideal, isothermal, plug-flow, tubular reactor with external recycle. This view justifies the frequently used name loop reactor. As is customary for the calculation of performance for tubular reactors, the rate equations are integrated from initial to final conditions within the inner balance limit. This calculation represents an implicit problem since the initial conditions depend on the result because of the recycle stream. Therefore, repeated trial and error calculations are needed for recycle... 

Positioners should be used to aehieve aeeuraey and repeatability of the eontrol-loop response. This is partieularly important with the open-loop eontrol method diseussed above. 

Each repeat forms a right-handed P-loop-a structure similar to those found in the two other classes of a/p structures described earlier. Sequential p-loop-a repeats are joined together in a similar way to those in the a/P-bar-rel stmctures. The P strands form a parallel p sheet, and all the a helices are on one side of the P sheet. However, the P strands do not form a closed barrel instead they form a curved open stmcture that resembles a horseshoe with a helices on the outside and a p sheet forming the inside wall of the horseshoe (Figure 4.11). One side of the P sheet faces the a helices and participates in a hydrophobic core between the a helices and the P sheet the other side of the P sheet is exposed to solvent, a characteristic other a/p structures do not have. 

The horseshoe structure is formed by homologous repeats of leucine-rich motifs, each of which forms a p-loop-a unit. The units are linked together such that the p strands form an open curved p sheet, like a horseshoe, with the a helices on the outside of the p sheet and the inside exposed to solvent. The invariant leucine residues of these motifs form the major part of the hydrophobic region between the a helices and the p sheet. 

In these p-helix structures the polypeptide chain is coiled into a wide helix, formed by p strands separated by loop regions. In the simplest form, the two-sheet p helix, each turn of the helix comprises two p strands and two loop regions (Figure 5.28). This structural unit is repeated three times in extracellular bacterial proteinases to form a right-handed coiled structure which comprises two adjacent three-stranded parallel p sheets with a hydrophobic core in between. 

The basic structural unit of these two-sheet p helix structures contains 18 amino acids, three in each p strand and six in each loop. A specific amino acid sequence pattern identifies this unit namely a double repeat of a nine-residue consensus sequence Gly-Gly-X-Gly-X-Asp-X-U-X where X is any amino acid and U is large, hydrophobic and frequently leucine. The first six residues form the loop and the last three form a p strand with the side chain of U involved in the hydrophobic packing of the two p sheets. The loops are stabilized by calcium ions which bind to the Asp residue (Figure S.28). This sequence pattern can be used to search for possible two-sheet p structures in databases of amino acid sequences of proteins of unknown structure. 

The two homologous repeats, each of 88 amino acids, at both ends of the TBP DNA-binding domain form two stmcturally very similar motifs. The two motifs each comprise an antiparallel p sheet of five strands and two helices (Figure 9.4). These two motifs are joined together by a short loop to make a 10-stranded p sheet which forms a saddle-shaped molecule. The loops that connect p strands 2 and 3 of each motif can be visualized as the stirmps of this molecular saddle. The underside of the saddle forms a concave surface built up by the central eight strands of the p sheet (see Figure 9.4a). Side chains from this side of the P sheet, as well as residues from the stirrups, form the DNA-binding site. No a helices are involved in the interaction area, in contrast to the situation in most other eucaryotic transcription factors (see below). 

FIGURE 12.27 The formation of a cruciform structure from a paliudromic sequence within DNA. The self-complementary Inverted repeats can rearrange to form hydrogen-bonded cruciform loops. 

---