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.
Urea is transported to the kidneys for excretion. A normal range for blood urea nitrogen is generally 8 to 24 mg/dl for adult males and 6 to 21 mg/dl for females. Generally, a high blood urea nitrogen level means that the kidneys are not performing well, particularly if the result is above 50mg/dl.