1 Leaf shutters are usually fitted within a lens assembly (central shutter), or more rarely immediately behind (behind-the-lens shutter) or, even more rarely, in front of a lens, and shut off the beam of light where it is narrow. 2  Focal-plane shutters are mounted near the focal plane and move to uncover the film or sensor.
DHEA levels begin to naturally decline by the age of 30. While normal levels for women in their 20s fall between 65 and 380 Âµg/dL, for women in their 30s and 40s, the average normal range is 45 to 270 and 32 to 240 Âµg/dL, respectively.
An elevated BUN:Cr due to a low or low-normal creatinine and a BUN within the reference range is unlikely to be of clinical significance. The ratio is predictive of prerenal injury when BUN:Cr exceeds 20 or when urea:Cr exceeds 100.he normal serum creatinine (sCr) varies with the subject's body muscle mass and with the technique used to measure it. For the adult male, the normal range is 0.6 to 1.2 mg/dl, or 53 to 106 Î¼mol/L by the kinetic or enzymatic method, and 0.8 to 1.5 mg/dl, or 70 to 133 Î¼mol/L by the older manual Jaffe jaffÃ©. reaction