E. Mechanical receptors are located in the lungs, upper airways, chest wall, and diaphragm which prevent overdistension of the lungs. F. Respiratory defense mechanisms: 1. filtration of air by the upper airways 2. mucociliary clearance system -which is decreased by infection, atropine, alcohol, dehydration,
However, one. of the most challenging aspects of forensic DNA analysis is the. interpretation of low-level testing results where it is difï¬cult to. distinguish reliably between noise and signal from template DNA. that is associated with an evidence sample (3,4).
To evaluate DNA purity, measure absorbance from 230nm to 320nm to detect other possible contaminants. The most common purity calculation is the ratio of the absorbance at 260nm divided by the reading at 280nm.Good-quality DNA will have an A 260 /A 280 ratio of 1.7â2.0.otal yield is obtained by multiplying the DNA concentration by the final total purified sample volume. DNA yield (Âµg) = DNA concentration Ã total sample volume (ml). However, DNA is not the only molecule that can absorb UV light at 260nm.