Population sizeIn population genetics and population ecology, population size (usually denoted N) is a countable quantity representing the number of individual organisms in a population. Population size is directly associated with amount of genetic drift, and is the underlying cause of effects like population bottlenecks and the founder effect. Genetic drift is the major source of decrease of genetic diversity within populations which drives fixation and can potentially lead to speciation events.
Photonic crystalA photonic crystal is an optical nanostructure in which the refractive index changes periodically. This affects the propagation of light in the same way that the structure of natural crystals gives rise to X-ray diffraction and that the atomic lattices (crystal structure) of semiconductors affect their conductivity of electrons. Photonic crystals occur in nature in the form of structural coloration and animal reflectors, and, as artificially produced, promise to be useful in a range of applications.
Dark fibreA dark fibre or unlit fibre is an unused optical fibre, available for use in fibre-optic communication. Dark fibre may be leased from a network service provider. Dark fibre originally referred to the potential network capacity of telecommunication infrastructure. Because the marginal cost of installing additional fibre optic cables is very low once a trench has been dug or conduit laid, a great excess of fibre was installed in the US during the telecom boom of the late 1990s and early 2000s.
Halabja massacreThe Halabja massacre (Kêmyabarana Helebce کیمیابارانی ھەڵەبجە), also known as the Halabja chemical attack, was a massacre of Kurdish people that took place on 16 March 1988, during the closing days of the Iran–Iraq War in Halabja, Iraq. The attack was part of the Al-Anfal Campaign in Kurdistan, as well as part of the Iraqi Army's attempt to repel the Iranian Operation Zafar 7. It took place 48 hours after the capture of the town by the Iranian Army.
