The Arabic alphabet, or Arabic abjad, is the Arabic script as it is codified for writing Arabic. It includes 28 letters. Most letters have contextual letterforms; the Arabic alphabet is considered an abjad, meaning it only uses consonants, but it is now considered an "impure abjad". As with other impure abjads, such as the Hebrew alphabet, scribes devised means of indicating vowel sounds by separate vowel diacritics; the basic Arabic alphabet contains 28 letters. Adaptations of the Arabic script for other languages added and removed some letters, as for Persian, Ottoman Turkish, Urdu, Malay, Pashto and Malayalam, all of which have additional letters as shown below. There are lower case letter forms. Many letters look similar but are distinguished from one another by dots above or below their central part; these dots are an integral part of a letter, since they distinguish between letters that represent different sounds. For example, the Arabic letters ب, ت and ث have the same basic shape, but have one dot below, two dots above and three dots above.

Both printed and written Arabic are cursive, with most of the letters within a word directly connected to the adjacent letters. There are two main collating sequences for the Arabic alphabet: hija; the original ʾabjadīy order, used for lettering, derives from the order of the Phoenician alphabet, is therefore similar to the order of other Phoenician-derived alphabets, such as the Hebrew alphabet. In this order, letters are used as numbers, Abjad numerals, possess the same alphanumeric code/cipher as Hebrew gematria and Greek isopsephy; the hijā’ī or alifbāʾī order, used where lists of names and words are sorted, as in phonebooks, classroom lists, dictionaries, groups letters by similarity of shape. The ʾabjadī order is not a simple historical continuation of the earlier north Semitic alphabetic order, since it has a position corresponding to the Aramaic letter samekh/semkat ס, yet no letter of the Arabic alphabet derives from that letter. Loss of sameḵ was compensated for by the split of shin ש into two independent Arabic letters, ش and ﺱ which moved up to take the place of sameḵ.

The six other letters that do not correspond to any north Semitic letter are placed at the end. This is vocalized as follows: ʾabjad hawwaz ḥuṭṭī kalaman saʿfaṣ qarashat thakhadh ḍaẓagh. Another vocalization is: ʾabujadin hawazin ḥuṭiya kalman saʿfaṣ qurishat thakhudh ḍaẓughThis can be vocalized as: ʾabujadin hawazin ḥuṭiya kalman ṣaʿfaḍ qurisat thakhudh ẓaghush Modern dictionaries and other reference books do not use the abjadī order to sort alphabetically; the hijāʾī order is never used as numerals. Another kind of hijāʾī order was used in the Maghreb until when it was replaced by the Mashriqi order; the Arabic alphabet is always cursive and letters vary in shape depending on their position within a word. Letters can exhibit up to four distinct forms corresponding to an initial, final, or isolated position. While some letters show considerable variations, others remain identical across all four positions. Letters in the same word are linked together on both sides by short horizontal lines, but six letters can only be linked to their preceding letter.

For example, أرارات has only isolated forms because each letter cannot be connected to its following one. In addition, some letter combinations are written as ligatures, notably lām-alif لا, the only mandatory ligature. Notes See the article Romanization of Arabic for details on various transliteration schemes. Names are transcribed as pronounced locally, not as pronounced in Literary Arabic. Regarding pronunciation, the phonemic values given are those of Modern Standard Arabic, taught in schools and universities. In practice, pronunciation may vary from region to region. For more details concerning the pronunciation of Arabic, consult the articles Arabic phonology and varieties of Arabic; the names of the Arabic letters can be thought of as abstractions of an older version where they were meaningful words in the Proto-Semitic language. Names of Arabic letters may have quite different names popularly. Six letters do not have a distinct medial form and have to be written with their final form without being connected to the next letter.

Their initial form matches the isolated form. The following letter is written in its initial form, or isolated form if it is the final letter in the word; the letter alif originated in the Phoenician alphabet as a consonant-sign indicating a glottal stop. Today it has lost its function as a consonant, together with ya’ and wāw, is a mater lectionis, a consonant sign standing in for a long vowel, or as support for certain diacritics. Arabic uses a diacritic sign, ء, called hamzah, to denote the glottal stop, written alone or with a carrier: alone: ء with a carrier: إ أ, ؤ, ئ. In academic work

John Dwyer McLaughlin was an American abstract painter. Based in California, he was a pioneer in minimalism and hard-edge painting. Considered one of the most significant Californian postwar artists, McLaughlin painted a focused body of geometric works that are devoid of any connection to everyday experience and objects, inspired by the Japanese notion of the void, he aimed to create paintings devoid of any object hood including but not limited to a gestures and figuration. This led him to the rectangle. Leveraging a technique of layering rectangular bars on adjacent planes, McLaughlin creates works that provoke introspection and a greater understanding of one's relationship to nature. John McLaughlin was born in Massachusetts, his father was a Massachusetts Superior Court judge and he had six siblings. His parents instilled in him an interest in art, most Asian art. McLaughlin served in both World Wars, his service in the United States Navy during World War I spanned from 1917 to 1921. In 1928 he married a grandniece of Ralph Waldo Emerson.

In 1935 they moved to Japan, where McLaughlin studied the language. When they returned to Boston in 1938, they opened The Tokaido, Inc. an art gallery which specialized in Japanese prints and other Asian items. After studying Japanese at the University of Hawaii in Honolulu, he served the United States Marine Corps in World War II as a translator. In the war, he worked in U. S. Army Intelligence as a translator in Japan, India and Burma. In 1945 he was awarded the Bronze Star for meritorious service. McLaughlin had begun painting during the 1930s late in life, he was self-taught, without receiving formal artistic training. His fondness for Asian art and his travels in that part of the world influenced his artistic style, he began painting full-time. A few of his earliest paintings were still lifes and landscapes, but the remainder of his pieces were abstracts. During this time period, he was one of just a few American artists creating abstracts. McLaughlin's work is characterized by a simplicity expressed as precise geometric forms rectangles.

His experiences in Asia were important in developing his style. Zen masters taught that spaces between objects could be more important than the objects themselves in facilitating meditation; the work of Kazimir Malevich and Piet Mondrian strongly influenced McLaughlin. He wrote: "With respect to my direct influences I must stress my interest in 15th and 16th century Japanese painters. I have found comfort in some aspects of thought expressed by Malevitch, I am indebted to Mondrian because his painting indicated that the natural extension of Neo-Plasticism is the abstract." From 1952 onward, he ceased using curves in his work. Paintings from his period show increasing simplification of form and color palette, he described his artistic philosophy: "My purpose is to achieve the abstract. I want to communicate only to the extent that the painting will serve to induce or intensify the viewer's natural desire for contemplation without benefit of a guiding principle. I must therefore free the viewer from the demands or special qualities imposed by the particular by omitting the image.

This I manage by the use of neutral forms."McLaughlin's first solo exhibition was in 1952 at the Felix Landau Gallery in Los Angeles. He showed with André Emmerich in New York and Zurich, his many other museum solo exhibition venues included the Pasadena Art Museum, Corcoran Gallery, La Jolla Museum of Contemporary Art, Whitney Museum of American Art. His work was included in numerous group exhibitions, including the landmark "Four Abstract Classicists" exhibit at the Los Angeles County Museum of Art; this show featuring the work of Karl Benjamin, Lorser Feitelson, Frederick Hammersley, was organized by Jules Langsner who, along with Peter Selz, coined the term "hard-edge painting" to describe the work of these four abstract artists. Langsner wrote: "Deliberately neutral in character, John McLaughlin's forms might be described as anonymous. Color serves him as a means of defining and regulating a form's relative importance in the composition; each painting represents the outcome of a process of refinement."A touring exhibition "Birth of the Cool: California Art and Culture at Midcentury" featured the abstract classicists.

New York Times art critic Ken Johnson wrote in his 2008 review of the show at the Addison Gallery of American Art: "Mr. McLaughlin's grid-based paintings exude a greater formal austerity, they are composed of smooth, flat rectangles of black, off-white and gray with blocks of color strategically inserted here and there. Inspired by Asian art and Zen Buddhism, they have a monastic air about them, but they are suave and materially sensuous too."Life magazine published a special issue in 1962 on the state of California. It highlighted five renowned artists, including John McLaughlin. McLaughlin died on March 22, 1976, in Dana Point at the age of 77. In 1963, the Pasadena Art Museum exhibited McLaughlin's first major museum retrospective curated by the legendary Walter Hopps. In 1968, the Corcoran Gallery of Art exhibited McLaughlin's second major museum retrospective curated by James Harithas. In 1975, the Laguna Art Museum held McLaughlin's second museum retrospective. In November 2016, McLaughlin was subject to a long overdue third major museum retrospective at LACMA.

A review of the show by art critic Christopher Knight affirms "McLaughlin occupies

Jan Hendrik Oort was a Dutch astronomer who made significant contributions to the understanding of the Milky Way and, a pioneer in the field of radio astronomy. His New York Times obituary called him "one of the century's foremost explorers of the universe". In 1955, Oort's name appeared in Life magazine's list of the 100 most famous living people, he has been described as "putting the Netherlands in the forefront of postwar astronomy."Oort determined that the Milky Way rotates and overturned the idea that the Sun was at its center. He postulated the existence of the mysterious invisible dark matter in 1932, believed to make up 84.5% of the total matter in the Universe and whose gravitational pull causes "the clustering of stars into galaxies and galaxies into connecting strings of galaxies". He discovered a group of stars orbiting the Milky Way but outside the main disk. Additionally Oort is responsible for a number of important insights about comets, including the realization that their orbits "implied there was a lot more solar system than the region occupied by the planets."The Oort cloud, the Oort constants, the asteroid, 1691 Oort, were all named after him.

Oort was born in Franeker, a small town in the Dutch province of Friesland, on April 28, 1900. He was the second son of Abraham Hermanus Oort, a physician, who died on May 12, 1941, Ruth Hannah Faber, the daughter of Jan Faber and Henrietta Sophia Susanna Schaaii, who died on November 20, 1957. Both of his parents came from families of clergymen, with his paternal grandfather, a Protestant clergyman with liberal ideas, who "was one of the founders of the more liberal Church in Holland" and who "was one of the three people who made a new translation of the Bible into Dutch." The reference is to Henricus Oort, the grandson of a famous Rotterdam preacher and, through his mother, Dina Maria Blom, the grandson of theologian Abraham Hermanus Blom, a "pioneer of modern biblical research". Several of Oort's uncles were pastors. "My mother kept up her interests in that, at least in the early years of her marriage", he recalled. "But my father was less interested in Church matters."In 1903 Oort's parents moved to Oegstgeest, near Leiden, where his father took charge of the Endegeest Psychiatric Clinic.

Oort's father, "was a medical director in a sanitorium for nervous illnesses. We lived in the director's house of the sanitorium, in a small forest, nice for the children, of course, to grow up in." Oort's younger brother, became a professor of plant diseases at the University of Wageningen. In addition to John, Oort had two younger sisters and an elder brother who died of diabetes when he was a student. Oort attended primary school in Oegstgeest and secondary school in Leiden, in 1917 went to Groningen University to study physics, he said that he had become interested in science and astronomy during his high-school years, conjectured that his interest was stimulated by reading Jules Verne. His one hesitation about studying pure science was the concern that it "might alienate one a bit from people in general", as a result of which "one might not develop the human factor sufficiently." But he overcame this concern and ended up discovering that his academic positions, which involved considerable administrative responsibilities, afforded a good deal of opportunity for social contact.

Oort chose Groningen because a well known astronomer, Jacobus Cornelius Kapteyn, was teaching there, although Oort was unsure whether he wanted to specialize in physics or astronomy. After studying with Kapteyn, Oort decided on astronomy. "It was the personality of Professor Kapteyn which decided me entirely", he recalled. "He was quite an inspiring teacher and his elementary astronomy lectures were fascinating." Oort began working on research with Kapteyn early in his third year. According to Oort one professor at Groningen who had considerable influence on his education was physicist Frits Zernike. After taking his final exam in 1921, Oort was appointed assistant at Groningen, but in September 1922, he went to the United States to do graduate work at Yale and to serve as an assistant to Frank Schlesinger of the Yale Observatory. At Yale, Oort was responsible for making observations with the Observatory's zenith telescope. "I worked on the problem of latitude variation", he recalled, "which is quite far away from the subjects I had so far been studying."

He considered his experience at Yale useful as he became interested in "problems of fundamental astronomy that felt was capitalized on and which influenced future lectures in Leiden." He "felt somewhat lonesome in Yale", but said that "some of my best friends were made in these years in New Haven." In 1924, Oort returned to the Netherlands to work at Leiden University, where he served as a research assistant, becoming Conservator in 1926, Lecturer in 1930, Professor Extraordinary in 1935. In 1926, he received his doctorate from Groningen with a thesis on the properties of high-velocity stars; the next year, Swedish astronomer Bertil Lindblad proposed that the rate of rotation of stars in the outer part of the galaxy decreased with distance from the galactic core, Oort, who said that he believed it was his colleague Willem de Sitter who had first drawn his attention to Lindblad's work, realized that Lindblad was correct and that the truth of his proposition could be demonstrated observationally.

Oort provided two formulae that d