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The 1903 Flyer was the first aircraft to make a successful, controllable, heavier-than-air flight. View the Flyer at different angles, the customized lightweight motor, and other related images for a complete picture of this breakthrough in aircraft…

The Ebola virus comprises a group of pathogenic agents that cause severe and deadly hemorrhagic fevers in humans and other primates. During 2014 and 2015, an Ebola virus epidemic in West Africa—predominantly, the countries of Guinea, Liberia, and…

The United Nations has proclaimed 2019 the International Year of the Periodic Table of Chemical Elements (IYPT2019). The same year also marks the 150th anniversary of the publication of Russian chemist Dmitri Mendeleev’s periodic table, containing…

The temperature at which matter reaches a lowest energy state and all thermal activity theoretically ceases. Absolute zero is popularly conceived as the coldest possible temperature that a given system of matter, such as an atom, may reach.…

Either the taking up of energy from radiation by the medium through which radiation is passing, or the taking up of matter in bulk by other matter. A simple example of the absorption of energy is how sunlight warms a tree's leaves (see…

A distinct phylum of helminths (parasitic worms), commonly known as the spiny- or thorny-headed worms. The phylum Acanthocephala comprises three classes: Archiacanthocephala, Palaeacanthocephala, and Eoacanthocephala (a suggested fourth class,…

A viral disease of humans caused by the human immunodeficiency virus (HIV), which attacks and compromises the body's immune system. Individuals infected with the human immunodeficiency virus (HIV) proceed through a spectrum of stages that ultimately…

A powdered, granular, or pelleted form of amorphous carbon characterized by very large surface area per unit volume because of an enormous number of fine pores. Activated carbon is capable of collecting gases, liquids, or dissolved substances on the…

Habituation to a specific practice, such as drinking alcoholic beverages or using drugs (for example, heroin, cocaine, or amphetamines), and disorders characterized by the chronic use of a drug, alcohol, or similar substance. Addiction and addictive…

A process in which atoms or molecules move from a bulk phase (that is, solid, liquid, or gas) onto a solid or liquid surface. An example is purification by adsorption where impurities are filtered from liquids or gases by their adsorption onto the…

The force exerted on a body whenever there is a relative velocity between the body and the air. There are only two basic sources of aerodynamic force: the pressure distribution and the frictional shear stress distribution exerted by the airflow on…

The applied science that deals with the dynamics of airflow and the resulting interactions between this airflow and solid boundaries. The solid boundaries may be a body immersed in the airflow (Fig. 1), or a duct of some shape through which the air…

A branch of engineering concerned primarily with the special problems of flight and other modes of transportation involving a heavy reliance on aerodynamics or fluid mechanics. The main emphasis in aeronautical engineering is on airplane and missile…

Behavior that is intended to threaten or inflict physical injury or emotional harm on another person or organism. Aggression is a type of behavior (physical or verbal, or both) displayed by an individual who aims or is motivated to harm another…