Density gradient

Density gradient

Density gradient is a spatial variation in density over an area. The term is used in the natural sciences to describe varying density of matter, but can apply to any quantity whose density can be measured. [1] [2]


Contents

Aerodynamics

In the study of supersonic flight, Schlieren photography observes the density gradient of air as it interacts with aircraft. [3]

Water

A steep density gradient in a body of water can have the effect of trapping energy and preventing convection, such a gradient is employed in solar ponds. In the case of salt water, sharp gradients can lead to stratification of different concentrations of salinity. This is called a Halocline. [4]

Biology

In the life sciences, a special technique called density gradient separation is used for isolating and purifying cells, viruses and subcellular particles.[5] Variations of this include Isopycnic centrifugation, Differential centrifugation, and Sucrose gradient centrifugation. A blood donation technique called Pheresis involves density gradient separation.

Geophysics

The understanding of what is at the centre of the earth, the earth core, requires the framework of density gradients in which elements and compounds then interact. Fast breeder nuclear reactor at the core of the earth is one theory by reason of density gradient and supported and espoused by J. Marvin Herndon (7 & 8).

Regional Economics

In the study of population, the density gradient can refer to the change in density in an urban area from the center to the periphery. [6]

References

  1. ^ "Non-Destructive Testing Resource Center - Glossary". http://www.ndt-ed.org/GeneralResources/Glossary/letter/d.htm. 
  2. ^ "Chicago Wilderness Journal, Volume 1 - Number 1 - November, 2003". http://www.chicagowilderness.org/pubprod/cwjournal/docs/CWJournal1003.pdf. 
  3. ^ "CFI-Shadowgraph/Schliren Photography for Aerodynamic Applications". http://pdf.aiaa.org/preview/1994/PV1994_2616.pdf. 
  4. ^ "Effects of sill processes and tidal forcing on exchange in eastern Long Island Sound". http://www.agu.org/pubs/crossref/1994/94JC00721.shtml. 
  5. ^ "GE Healthcare Density Gradient Separation". http://www6.amershambiosciences.com/aptrix/upp00919.nsf/Content/CellSep_EduC~dgs. 
  6. ^ "The Spatial Distribution of Population in 48 World Cities: Implications for Economies in Transition". http://www.bus.wisc.edu/realestate/pdf/pdf/Complete%20Spatial%20Distribution%20of%20Population%20in%2050%20World%20Ci.pdf. 
  • 7. Herndon, J. Marvin (1994) Planetary and Protostellar Nuclear Fission: Implications for Planetary Change, Stellar Ignition and Dark Matter Proceedings: Mathematical and Physical Sciences, Vol. 445, No. 1924 (May 9, 1994) , pp. 453-461
  • 8. Herndon, J. Marvin (1996) Substructure of the inner core of the Earth Vol. 93, Issue 2, 646-648, January 23, 1996, PNAS

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  • density gradient centrifugation — noun (biology) The separation of cells, cell components or complex molecules on the basis of their density differences by centrifuging them to their density equilibrium positions in gradients established in appropriate solutions • • • Main Entry …   Useful english dictionary

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  • cesium chloride equilibrium density gradient centrifugation — cesium chloride equilibrium density gradient centrifugation. См. центрифугирование в градиенте плотности хлорида цезия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995… …   Молекулярная биология и генетика. Толковый словарь.

  • sucrose equilibrium density gradient centrifugation — sucrose equilibrium density gradient centrifugation. См. центрифугирование в градиенте плотности сахарозы. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

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  • Gradient (disambiguation) — Gradient may refer to:* Gradient, in vector calculus, a vector field representing the maximum rate of increase of the scalar field direction of the maximum change. * Slope or grade, referring to the inclination of a road or other geographic… …   Wikipedia

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