Diaphragm (optics) bright spots, for example night cityscapes. Some cameras, such as the Olympus XA or lenses such as the MC Zenitar-ME1, however, use a two-bladed diaphragm with right-angle blades creating a square aperture. Similarly, out-of-focus points of light (circles of confusion) appear as polygons with the same number of sides as the aperture has blades. If the blurred light is circular, then it can be inferred that the aperture is either round or the image was shot "wide-open" (with the blades recessed into the sides of the lens, allowing the interior edge of the lens barrel to effectively become the iris).
Diaphragm pacing an electric current through electrodes that are attached internally. The diaphragm contracts, expanding the chest cavity, causing air to be sucked into the lungs (inspiration). When not stimulated, the diaphragm relaxes and air moves out of the lungs (expiration). According to the United States Medicare system, phrenic nerve stimulators are indicated for "selected patients with partial or complete respiratory insufficiency" and "can be effective only if the patient has an intact phrenic nerve and diaphragm". Common patient diagnoses for phrenic nerve pacing include patients with spinal cord injury, central sleep apnea (i.e., Ondine's curse), and diaphragm paralysis. There are currently