Chemical vapor depositionChemical vapor deposition (CVD) is a vacuum deposition method used to produce high-quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (substrate) is exposed to one or more volatile precursors, which react and/or decompose on the substrate surface to produce the desired deposit. Frequently, volatile by-products are also produced, which are removed by gas flow through the reaction chamber.
State (polity)A state is a centralized political organization that imposes and enforces rules over a population within a territory. Definitions of a state are disputed. One widely used definition comes from the sociologist Max Weber: a "state" is a polity that maintains a monopoly on the legitimate use of violence, although other definitions are common. Absence of a state does not preclude the existence of a society, such as stateless societies like the Haudenosaunee Confederacy that "do not have either purely or even primarily political institutions or roles".
State religionA state religion (also called official religion) is a religion or creed officially endorsed by a sovereign state. A state with an official religion (also known as confessional state or religious state), while not a secular state, is not necessarily a theocracy. State religions are official or government-sanctioned establishments of a religion, but the state does not need to be under the control of the clergy (as in a theocracy), nor is the state-sanctioned religion necessarily under the control of the state.
Air mass (astronomy)In astronomy, air mass or airmass is a measure of the amount of air along the line of sight when observing a star or other celestial source from below Earth's atmosphere . It is formulated as the integral of air density along the light ray. As it penetrates the atmosphere, light is attenuated by scattering and absorption; the thicker atmosphere through which it passes, the greater the attenuation. Consequently, celestial bodies when nearer the horizon appear less bright than when nearer the zenith.
Thermal shockThermal shock is a phenomenon characterized by a rapid change in temperature that results in a transient mechanical load on an object. The load is caused by the differential expansion of different parts of the object due to the temperature change. This differential expansion can be understood in terms of strain, rather than stress. When the strain exceeds the tensile strength of the material, it can cause cracks to form and eventually lead to structural failure.
Opacity (optics)Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shielding material, glass, etc. An opaque object is neither transparent (allowing all light to pass through) nor translucent (allowing some light to pass through). When light strikes an interface between two substances, in general some may be reflected, some absorbed, some scattered, and the rest transmitted (also see refraction).
Epicyclic gearingAn epicyclic gear train (also known as a planetary gearset) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates the planet and sun gears mesh so that their pitch circles roll without slip. A point on the pitch circle of the planet gear traces an epicycloid curve. In this simplified case, the sun gear is fixed and the planetary gear(s) roll around the sun gear.
Apple WatchThe Apple Watch is a line of smartwatches produced by Apple Inc. It incorporates fitness tracking, health-oriented capabilities, and wireless telecommunication, and integrates with iOS and other Apple products and services. The Apple Watch was released in April 2015, and quickly became the best-selling wearable device: 4.2 million were sold in the second quarter of fiscal 2015, and more than 115 million people were estimated to use an Apple Watch as of December 2022.
RolexRolex SA (ˈroʊlɛks) is a Swiss watch designer and manufacturer based in Geneva, Switzerland. Founded in 1905 as Wilsdorf and Davis by Hans Wilsdorf and Alfred Davis in London, the company registered Rolex as the brand name of its watches in 1908 and became Rolex Watch Co. Ltd. in 1915. After World War I, the company moved its base of operations to Geneva because of the unfavorable economy in the United Kingdom. In 1920, Hans Wilsdorf registered Montres Rolex SA in Geneva as the new company name (montre is French for clock or watch); it later became Rolex SA.
No-hair theoremThe no-hair theorem states that all stationary black hole solutions of the Einstein–Maxwell equations of gravitation and electromagnetism in general relativity can be completely characterized by only three independent externally observable classical parameters: mass, electric charge, and angular momentum.
