Recombination limited sampling

Another issue that can be clarified with the aid of numerical simulations is that of the recombination profile. Mailiaras and Scott [145] have found that recombination takes place closer to the contact that injects the less mobile carrier, regardless of the injection characteristics. In Figure 13-12, the calculated recombination profiles arc shown for an OLED with an ohmic anode and an injection-limited cathode. When the two carriers have equal mobilities, despite the fact that the hole density is substantially larger than the electron density, electrons make it all the way to the anode and the recombination profile is uniform throughout the sample. 

Limited proteolysis tends to introduce heterogeneity into the protein sample, and if the protein can be overexpressed using recombinant techniques, it is better to engineer these deletions into the protein at the gene level. 

Examination of the offspring in generation 3 shows that our prediction is met in all cases but one the last son in the pedigree has a 1,1 genotype but is unaffected. We infer that a crossover occurred in the chromosome transmitted from the mother to this offspring. Thus, on the basis of the limited information provided by this family, we estimate the recombination frequency to be one sixth, or about 17%. In other words, we predict that, about 17% of the time, a crossover will occur between the marker locus and the disease locus. In practice, a much larger sample of families is used to provide a more accurate estimate of the recombination frequency. If the recombination frequency is estimated to be 50%, the two loci are unlinked and may be on different chromosomes. 

Limitations notwithstanding, colony hybridization techniques have been used successfully for a number of years to monitor environmental samples. Representative examples include detection of naphthalene and toluene degraders in contaminated soils (Sayler et al., 1985), recombinant organisms in groundwater (Jain et al., 1987 ... 

The third factor that is important in determining the detection limit is the conversion efficiency of the kinetics. A conversion efficiency of 1.0 requires that the airstream have a velocity substantially less than 200 m/s because uniform mixing of NO is very difficult. At the same time, collisions of the sample airstream with wall surfaces in slower inlet systems may cause a chemical loss of CIO and BrO, because they are both reactive with wall surfaces. The solution to this problem was suggested by Soderman (83). Soderman s novel design consists of two nested ducts in which the air speed is decreased from 200 m/s to 60 m/s in a 14-cm-diameter outer duct that protrudes 60 cm in front of the left wing pod and is reduced to 20 m/s inside a smaller 5-cm-square duct in which the measurements are made. The entrance to the smaller measurement duct is 60 cm downstream of the entrance to the outer duct, and the NO injector tubes, the two CIO detection axes, and the one BrO axis are 25 cm, 37.5 cm, 55 cm, and 72.5 cm downstream of the entrance of the measurement duct. Ninety percent of the air that enters the outer duct bypasses the measurement duct through additional duct work, and only the center 10% of the airstream is captured and sampled by the measurement duct. These two flows are recombined downstream of the instrument and are vented out the side of the wing pod that houses the instrument. 

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