pit

Examples of pit in the following topics:

• Using Interference to Read CDs and DVDs

  • These discs are flat, usually made of aluminum, and have microscopic pits and lands on one of the flat surfaces (as shown in ).
  • If the beam hits a pit, it gets scattered and is recorded as a value of zero.
  • These microscopic pits and lands cover the entire surface of the disc in a spiral path, starting in the center and working its way outward.
  • These pits also act as slits and cause the light to be diffracted as it is reflected back, which causes an iridescent effect.
  • In this early version of an optical disc, you can see the pits and lands which either reflect back light or scatter it.

• Edema

  • Cutaneous edema is referred to as pitting when, after pressure is applied to a small area, the indentation persists for some time after the release of the pressure.
  • Peripheral pitting edema, as shown in , is the more common type, resulting from water retention.
  • Non-pitting edema is observed when the indentation does not persist.
  • Peripheral pitting edema results from water retention.

• Microscopic Anatomy of the Stomach

  • The epithelium of the stomach forms deep pits, called fundic or oxyntic glands.
  • Different types of cells are at different locations down the pits.
  • The cells at the base of these pits are chief cells that are responsible for the production of pepsinogen, an inactive precursor of pepsin, which degrades proteins.
  • Further up the pits, parietal cells produce gastric acid and a vital substance, intrinsic factor.
  • Near the top of the pits, closest to the contents of the stomach, there are mucus-producing cells called goblet cells that help protect the stomach from self-digestion.

• Diffraction Gratings: X-Ray, Grating, Reflection

  • This is a side effect of their manufacture, as one surface of a CD has many small pits in the plastic, arranged in a spiral; that surface has a thin layer of metal applied to make the pits more visible.
  • The structure of a DVD is optically similar, although it may have more than one pitted surface, and all pitted surfaces are inside the disc.

• Sculpture of the Qin Dynasty

  • Estimates from 2007 were that the three pits containing the Terracotta Army held more than 8,000 soldiers, 130 chariots with 520 horses and 150 cavalry horses, the majority of which remained buried in the pits nearby Qin Shi Huang's mausoleum.
  • Other terracotta non-military figures were found in other pits, including officials, acrobats, strongmen and musicians.

• Angular Position, Theta

  • Each pit used to record sound along this line moves through the same angle in the same amount of time.
  • The pits along a line from the center to the edge all move through the same angle Δ in a time Δt.

• Ceramics in the Jomon Period

  • The Jōmon communities consisted of hundreds or even thousands of people, who dwelt in simple houses of wood and thatch set into shallow earthen pits to provide warmth from the soil.
  • The oldest examples of Jōmon pottery have flat bottoms, though pointed bottoms (meant to be held in small pits in the earth) became common later.

• Dental Caries

  • Though most trapped food is left between teeth, over 80% of cavities occur inside pits and fissures on chewing surfaces where brushing, fluoride, and saliva cannot reach to remineralize the tooth as they do on easy-to-reach surfaces that develop few cavities.
  • At times, pit and fissure caries may be difficult to detect .
  • The progression of pit and fissure caries resembles two triangles with their bases meeting along the junction of enamel and dentin.

• Edema Caused by Loss of Plasma Proteins

  • Peripheral pitting edema results from water retention.

• Angular Velocity, Omega

  • To find the precise relationship between angular and linear velocity, we again consider a pit on the rotating CD.
  • This pit moves an arc length Δs in a time Δt, and so it has a linear velocity v = Δs/Δt.