Phonology is a branch of linguistics concerned with the systematic organization of sounds in spoken languages and signs in sign languages. It used to be only the study of the systems of phonemes in spoken languages, but it may cover any linguistic analysis either at a level beneath the word or at all levels of language where sound or signs are structured to convey linguistic meaning. Sign languages have a phonological system equivalent to the system of sounds in spoken languages; the building blocks of signs are specifications for movement and handshape. The word'phonology' can refer to the phonological system of a given language; this is one of the fundamental systems which a language is considered to comprise, like its syntax, its morphology and its vocabulary. Phonology is distinguished from phonetics. While phonetics concerns the physical production, acoustic transmission and perception of the sounds of speech, phonology describes the way sounds function within a given language or across languages to encode meaning.

For many linguists, phonetics belongs to descriptive linguistics, phonology to theoretical linguistics, although establishing the phonological system of a language is an application of theoretical principles to analysis of phonetic evidence. Note that this distinction was not always made before the development of the modern concept of the phoneme in the mid 20th century; some subfields of modern phonology have a crossover with phonetics in descriptive disciplines such as psycholinguistics and speech perception, resulting in specific areas like articulatory phonology or laboratory phonology. The word phonology comes from phōnḗ, "voice, sound," and the suffix - logy. Definitions of the term vary. Nikolai Trubetzkoy in Grundzüge der Phonologie defines phonology as "the study of sound pertaining to the system of language," as opposed to phonetics, "the study of sound pertaining to the act of speech". More Lass writes that phonology refers broadly to the subdiscipline of linguistics concerned with the sounds of language, while in more narrow terms, "phonology proper is concerned with the function and organization of sounds as linguistic items."

According to Clark et al. it means the systematic use of sound to encode meaning in any spoken human language, or the field of linguistics studying this use. Early evidence for a systematic study of the sounds in a language appears in the 4th century BCE Ashtadhyayi, a Sanskrit grammar composed by Pāṇini. In particular the Shiva Sutras, an auxiliary text to the Ashtadhyayi, introduces what may be considered a list of the phonemes of the Sanskrit language, with a notational system for them, used throughout the main text, which deals with matters of morphology and semantics; the study of phonology as it exists today is defined by the formative studies of the 19th-century Polish scholar Jan Baudouin de Courtenay, who shaped the modern usage of the term phoneme in a series of lectures in 1876-1877. The word phoneme had been coined a few years earlier in 1873 by the French linguist A. Dufriche-Desgenettes. In a paper read at the 24th of May meeting of the Société de Linguistique de Paris, Dufriche-Desgenettes proposed that phoneme serve as a one-word equivalent for the German Sprachlaut.

Baudouin de Courtenay's subsequent work, though unacknowledged, is considered to be the starting point of modern phonology. He worked on the theory of phonetic alternations, may have had an influence on the work of Saussure according to E. F. K. Koerner. An influential school of phonology in the interwar period was the Prague school. One of its leading members was Prince Nikolai Trubetzkoy, whose Grundzüge der Phonologie, published posthumously in 1939, is among the most important works in the field from this period. Directly influenced by Baudouin de Courtenay, Trubetzkoy is considered the founder of morphophonology, although this concept had been recognized by de Courtenay. Trubetzkoy developed the concept of the archiphoneme. Another important figure in the Prague school was Roman Jakobson, one of the most prominent linguists of the 20th century. In 1968 Noam Chomsky and Morris Halle published The Sound Pattern of English, the basis for generative phonology. In this view, phonological representations are sequences of segments made up of distinctive features.

These features were an expansion of earlier work by Roman Jakobson, Gunnar Fant, Morris Halle. The features describe aspects of articulation and perception, are from a universally fixed set, have the binary values + or −. There are at least two levels of representation: underlying representation and surface phonetic representation. Ordered phonological rules govern how underlying representation is transformed into the actual pronunciation. An important consequence of the influence SPE had on phonological theory was the downplaying of the syllable and the emphasis on segments. Furthermore, the generativists folded morphophonology into phonology, which both solved and created problems. Natural phonology is a theory based on the publications of its proponent David Stampe in 1969 and in 1979. In this view, phonology is based on a set of universal ph

Heinrich Albertz was a German Protestant theologian and politician of the Social Democratic Party. He served as Governing Mayor of Berlin from 1966 to 1967. Heinrich Albertz was born in Breslau, in the Prussian province of Silesia, to the court preacher and consistorial councilor Hugo Albertz and his second wife Elisabeth, née Meinhof, his elder half brother was the Resistance fighter Martin Albertz. Having obtained his baccalaureate in 1933, he went on to study theology at the universities of Breslau and Berlin. Under the Nazi regime, he maintained contact to circles of the banned Social Democratic Party; as a member of the Confessing Church opposing the Nazis, he showed solidarity with the imprisoned pastor Martin Niemöller, was arrested several times and conscripted into the Wehrmacht in 1941. After World War II Albertz moved to Celle, where the British occupation authorities entrusted him with the reception of expellees and displaced persons, he in 1946 became a member of the Landtag of Lower Saxony.

In 1948 he was appointed minister for expellee affairs in the Lower Saxon state cabinet under Minister-President Hinrich Wilhelm Kopf. Since 1950 he was a member of the SPD federal board, he was a Christian pacifist and opposed the production and placement of nuclear weapons on German soil. When the Kopf cabinet was succeeded by the right-wing government of Minister-President Heinrich Hellwege upon the 1955 state elections, Albertz continued his career as a state secretary under the West Berlin mayor Otto Suhr. In 1961 he became Senator of the Interior under Mayor Willy Brandt and deputy mayor in 1963; when Brandt joined the German grand coalition government of Chancellor Kurt Georg Kiesinger, Albertz succeeded him and was elected governing mayor of West Berlin by the Abgeordnetenhaus parliament on 14 December 1966. Albertz, standing in the shadow of his popular predecessor, led the Social Democrats into the following state election held on 12 March 1967; the SPD was able to maintain its absolute majority.

Albertz' term in office was characterized by the rising student revolts culminating during the state visit by Shah Mohammad Reza Pahlavi and his wife Farah Pahlavi. On 2 June 1967 Pahlavi was received in West Berlin, accompanied by violent clashes of protesters with Iranian secret police collaborators and massive police forces, whereby the student Benno Ohnesorg was shot by police officer Karl-Heinz Kurras, an incident that became a turning point in the devolution of the German student movement. On 28 September Mayor Albertz was forced to resign after an investigation into the police's role in the killing; the Abgeordnetenhaus elected Klaus Schütz his successor. From 1970 he worked from 1974 to 1979 in Berlin-Zehlendorf; when on 27 February 1975 the Movement 2 June militant group abducted the Christian Democrat candidate for Mayor of West Berlin Peter Lorenz, Albertz agreed to accompany the exchanged prisoners, among them Verena Becker and Gabriele Kröcher-Tiedemann, on their flight to South Yemen.

Retired in 1979, he joined the German peace movement of the 1980s and several protests against the NATO Double-Track Decision. Albertz died in a Bremen nursing home on 18 May 1993. Newspaper clippings about Heinrich Albertz in the 20th Century Press Archives of the ZBW

GCaMP is a genetically encoded calcium indicator, or GECI developed by Junichi Nakai. GCaMP is created from a fusion of green fluorescent protein, M13, a peptide sequence from myosin light chain kinase; the advantage of GECI's is. The first transgenic mouse expressing a GCaMP was reported in 2004 and GCaMP was subsequently improved to GCaMP2, stable at mammalian body temperatures and enabled the first in vivo mammalian recordings using a GECI. GCaMPs have been subsequently modified to progressively improve the range of the fluorescence signal, resulting in GCaMP3 through GCaMP-X. Additionally, red fluorescence GECIs, termed "RCaMPs" have been developed to expand the spectral options for multi-lineage imaging. GFP is circularly permutated so that the N- and C-termini are fused, creating a new terminus in the middle of the protein. Fused to the new terminus is calmodulin and the M13 domain of a myosin light chain kinase. Calmodulin is a hinge-like protein that binds to four calcium ions via E-F motifs.

When calcium is present, CaM undergoes a conformational change, the hinge region is able to bind helical peptide chains on target proteins, such as M13. In the absence of calcium, the circularly permutated fluorescent proteins exist in a poorly fluorescent state due to a water pathway that enables protonation of the chromophore and poor absorbance at the excitation wavelengths. Ca2+ binding to the calmodulin moiety results in a structural shift that eliminates this solvent pathway, rapid de-protonation of the chromophore, bright fluorescence. Optogenetics