Home guard is a title given to various military organizations at various times, with the implication of an emergency or reserve force raised for local defense. The term "home guard" was first officially used in the American Civil War, starting with units formed by German immigrants in Missouri, and may derive from possible historic use of the term Heimwehr ("home guard") to describe units officially known as Landwehr ("country guard"), or from an attempted translation of landwehr. Military units Active Historical Aizsargi (Latvia, 1919–1940) Home Guard (Unionist), during the American Civil War Confederate Home Guard (1861–1865) during the American Civil War Croatian Home Guard, several historic military formations during 19th and 20th century Czechoslovak Home Guard (1918–1919) Home Guard (Austria) (Heimwehr) (1920–1938) paramilitary unit of Fatherland Front Party Home Guard (New Zealand) (1940–1943) Home Guard (United Kingdom) (1940–1944) Home...

A lead sheet or fake sheet is a form of musical notation that specifies the essential elements of a popular song: the melody, lyrics and harmony. The melody is written in modern Western music notation, the lyric is written as text below the staff and the harmony is specified with chord symbols above the staff. The lead sheet does not describe the chord voicings, voice leading, bass line or other aspects of the accompaniment. These are specified later by an arranger or improvised by the performers, and are considered aspects of the arrangement or performance of a song, rather than a part of the song itself. A lead sheet may also specify an instrumental part or theme, if this is considered essential to the song's identity. For example, the opening guitar riff from Deep Purple's "Smoke on the Water" is a part of the song; any performance of the song should include the guitar riff, and any imitation of that guitar riff is an imitation of the song. Thus the riff belongs on the lead sheet. A collected volume of lead sheets may be known as a fake book, due to the improvisational nature of its use: when presented with a lead sheet, proficient musicians...

Metrology is the scientific study of measurement. It establishes a common understanding of units, crucial in linking human activities. Modern metrology has its roots in the French Revolution's political motivation to standardise units in France when a length standard taken from a natural source was proposed. This led to the creation of the decimal-based metric system in 1795, establishing a set of standards for other types of measurements. Several other countries adopted the metric system between 1795 and 1875; to ensure conformity between the countries, the Bureau International des Poids et Mesures (BIPM) was established by the Metre Convention. This has evolved into the International System of Units (SI) as a result of a resolution at the 11th General Conference on Weights and Measures (CGPM) in 1960.Metrology is divided into three basic overlapping activities: The definition of units of measurement The realisation of these units of measurement in practice Traceability—linking measurements made in practice to the reference standardsThese overlapping activities are used in varying degrees by...

A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic CCD for Cathode Current Departs. A conventional current describes the direction in which positive charges move. Electrons have a negative electrical charge, so the movement of electrons is opposite to that of the conventional current flow. Consequently, the mnemonic cathode current departs also means that electrons flow into the device's cathode from the external circuit. For example, the end of a household battery marked with a + (plus) is the cathode. The electrode through which conventional current flows the other way, into the device, is termed an anode. Charge flow Conventional current flows from cathode to anode outside of the cell or device (with electrons moving in the opposite direction), regardless of the cell or device type and operating mode. Cathode polarity with respect to the anode can be positive or negative depending on how the device is being operated. Inside a device or a cell, positively charged cations always move...

Melanism is the congenital excess of melanin in an organism resulting in dark pigment. Pseudomelanism, also called abundism, is another variant of pigmentation, identifiable by dark spots or enlarged stripes, which cover a large part of the body of the animal, making it appear melanistic.The morbid deposition of black matter, often of a malignant character causing pigmented tumors, is called melanosis. Adaptation Melanism related to the process of adaptation is called adaptive. Most commonly, dark individuals become fitter to survive and reproduce in their environment as they are better camouflaged. This makes some species less conspicuous to predators, while others, such as leopards, use it as a foraging advantage during night hunting. Typically, adaptive melanism is heritable: A dominant allele, which is entirely or nearly entirely expressed in the phenotype, is responsible for the excessive amount of melanin. Adaptive melanism has been shown to occur in a variety of animals, including mammals such as squirrels, many cats and canids, and coral snakes. Adaptive melanism can lead to the creation of morphs...