Ultrafast laser spectroscopy
Ultrafast laser spectroscopy is a spectroscopic technique that uses ultrashort pulse lasers for the study of dynamics on short time scales. Different methods are used to examine dynamics of charge carriers and molecules. Many different procedures have been developed spanning different time scales and photon energy ranges. Dynamics on the as to fs time scale is in general too fast to be measured electronically. Most measurements are done by employing a sequence of ultrashort light pulses to initiate a process and record its dynamics; the width of the light pulses have to be on the same scale as the dynamics, to be measured. Ti-sapphire lasers are tunable lasers which emit near-infrared light. Ti-sapphire laser oscillators use Ti doped-sapphire crystals as a gain medium and Kerr lens modelocking to achieve sub-picosecond light pulses. Typical Ti:sapphire oscillator pulses have nJ energy and repetition rates 70-100 MHz. Chirped pulse amplification through regenerative amplification can be used to attain higher pulse energies.
To amplify, laser pulses from the Ti:sapphire oscillator must first be stretched in time to prevent, damage to optics, are injected into the cavity of another laser where pulses are amplified at a lower repetition rate. Regeneratively amplified pulses can be further amplified in a multi-pass amplified. Following amplification, the pulses are recompressed to pulse widths similar to the original pulse widths. A dye laser is a four-level laser. Pumped by a laser with a fixed wavelength, due to various dye types you use, different dye lasers can emit beams with different wavelengths. A ring laser design is most used in a dye laser system. Tuning elements, such as a diffraction grating or prism, are incorporated in the cavity; this allows only light in a narrow frequency range to resonate in the cavity and be emitted as laser emission. The wide tuneability range, high output power, pulsed or CW operation make the dye laser useful in many physical & chemical studies. A fiber laser is generated first from a laser diode.
The laser diode couples the light into a fiber where it will be confined. Different wavelengths can be achieved with the use of doped fiber; the pump light from the laser diode will excite a state in the doped fiber which can drop in energy causing a specific wavelength to be emitted. This wavelength may be different from that of the pump light and more useful for a particular experiment. Ultrafast optical pulses can be used to generate x-ray pulses in multiple ways. An optical pulse can excite an electron pulse via the photoelectric effect, acceleration across a high potential gives the electrons kinetic energy; when the electrons hit a target they generate both characteristic bremsstrahlung. A second method is via laser induced plasma; when high intensity laser light is incident on a target, it strips electrons off the target creating a negatively charged plasma cloud. The strong Coulomb force due to the ionized material in the center of the cloud accelerates the electrons back to towards the nuclei left behind.
Upon collision with the nuclei and characteristic emission x-rays are given off. This method of x-ray generation scatters photons in all directions, but generates picosecond x-ray pulses. In order for accurate spectroscopic measurements to be made, several characteristics of the laser pulse need to be known. Information about pulse duration can be determined through autocorrelation measurements, or from cross correlation with another well characterized pulse. Methods allowing for complete characterization of pulses include frequency-resolved optical gating and spectral phase interferometry for direct electric-field reconstruction. Pulse shaping is to modify the pulses from the source in a well-defined manner, including manipulation on pulse’s amplitude and duration. To amplify pulse’s intensity, chirped pulse amplification is applied, which includes a pulse stretcher and compressor, it will not change the phase of the pulse during the amplification. Pulse compression is achieved by first chirping the pulse in a nonlinear material and broadening the spectrum, with a following compressor for chirp compensation.
Fiber compressor is used in this case. Pulse shapers refer to optical modulators which applies Fourier transforms to laser beam. Depending on which property of light is controlled, modulators are called intensity modulators, phase modulators, polarization modulators, spatial light modulators. Depending on the modulation mechanism, optical modulators are divided into Acoustic-optic modulators, Electro-optic modulators, Liquid crystal modulators etc; each is dedicated into different applications. High harmonic generation is the nonlinear process where intense laser radiation is converted from one fixed frequency to high harmonics of that frequency by ionization and recollision of an electron, it was first observed in 1987 by McPherson et al. who generated harmonic emission up to the 17th order at 248 nm in neon gas. HHG is seen by focusing an ultra-fast, high-intensity, near-IR pulse into a noble gas at intensities of and it generates coherent pulses in the XUV to Soft X-ray region of the spectrum.
It is realizable on a laboratory scale as opposed to large free electron-laser facilities. High harmonic generation in atoms is well understood in terms of the three-step model. Ioni
Solid is one of the four fundamental states of matter. In solids particles are packed, it is characterized by structural resistance to changes of shape or volume. Unlike liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does; the atoms in a solid are bound to each other, either in a regular geometric lattice or irregularly. Solids cannot be compressed with little pressure whereas gases can be compressed with little pressure because in gases molecules are loosely packed; the branch of physics that deals with solids is called solid-state physics, is the main branch of condensed matter physics. Materials science is concerned with the physical and chemical properties of solids. Solid-state chemistry is concerned with the synthesis of novel materials, as well as the science of identification and chemical composition; the atoms, molecules or ions that make up solids may be arranged in an orderly repeating pattern, or irregularly.
Materials whose constituents are arranged in a regular pattern are known as crystals. In some cases, the regular ordering can continue unbroken over a large scale, for example diamonds, where each diamond is a single crystal. Solid objects that are large enough to see and handle are composed of a single crystal, but instead are made of a large number of single crystals, known as crystallites, whose size can vary from a few nanometers to several meters; such materials are called polycrystalline. All common metals, many ceramics, are polycrystalline. In other materials, there is no long-range order in the position of the atoms; these solids are known as amorphous solids. Whether a solid is crystalline or amorphous depends on the material involved, the conditions in which it was formed. Solids that are formed by slow cooling will tend to be crystalline, while solids that are frozen are more to be amorphous; the specific crystal structure adopted by a crystalline solid depends on the material involved and on how it was formed.
While many common objects, such as an ice cube or a coin, are chemically identical throughout, many other common materials comprise a number of different substances packed together. For example, a typical rock is an aggregate of several different minerals and mineraloids, with no specific chemical composition. Wood is a natural organic material consisting of cellulose fibers embedded in a matrix of organic lignin. In materials science, composites of more than one constituent material can be designed to have desired properties; the forces between the atoms in a solid can take a variety of forms. For example, a crystal of sodium chloride is made up of ionic sodium and chlorine, which are held together by ionic bonds. In diamond or silicon, the atoms share form covalent bonds. In metals, electrons are shared in metallic bonding; some solids most organic compounds, are held together with van der Waals forces resulting from the polarization of the electronic charge cloud on each molecule. The dissimilarities between the types of solid result from the differences between their bonding.
Metals are strong and good conductors of both electricity and heat. The bulk of the elements in the periodic table, those to the left of a diagonal line drawn from boron to polonium, are metals. Mixtures of two or more elements in which the major component is a metal are known as alloys. People have been using metals for a variety of purposes since prehistoric times; the strength and reliability of metals has led to their widespread use in construction of buildings and other structures, as well as in most vehicles, many appliances and tools, road signs and railroad tracks. Iron and aluminium are the two most used structural metals, they are the most abundant metals in the Earth's crust. Iron is most used in the form of an alloy, which contains up to 2.1% carbon, making it much harder than pure iron. Because metals are good conductors of electricity, they are valuable in electrical appliances and for carrying an electric current over long distances with little energy loss or dissipation. Thus, electrical power grids rely on metal cables to distribute electricity.
Home electrical systems, for example, are wired with copper for its good conducting properties and easy machinability. The high thermal conductivity of most metals makes them useful for stovetop cooking utensils; the study of metallic elements and their alloys makes up a significant portion of the fields of solid-state chemistry, materials science and engineering. Metallic solids are held together by a high density of shared, delocalized electrons, known as "metallic bonding". In a metal, atoms lose their outermost electrons, forming positive ions; the free electrons are spread over the entire solid, held together by electrostatic interactions between the ions and the electron cloud. The large number of free electrons gives metals their high values of electrical and thermal conductivity; the free electrons prevent transmission of visible light, making metals opaque and lustrous. More advanced models of metal properties consider the effect of the positive ions cores on the delocalised electrons.
As most metals have crystalline structure, those ions are arranged into a periodic lattice. Mathematically, the potential of the ion cores can be treated by various models, the simplest being the nearly free electron model. Minerals are
Kingdom of Egypt
The Kingdom of Egypt was the de jure independent Egyptian state established under the Muhammad Ali Dynasty in 1922 following the Unilateral Declaration of Egyptian Independence by the United Kingdom. Until the Anglo-Egyptian treaty of 1936, the Kingdom was only nominally independent, since the British retained control of foreign relations, the military and the Anglo-Egyptian Sudan. Between 1936 and 1952, the British continued to maintain military presence and political advisers, at a reduced level; the legal status of Egypt had been convoluted, due to its de facto breakaway from the Ottoman Empire in 1805, its occupation by Britain in 1882, its transformation into a sultanate and British protectorate in 1914. In line with the change in status from sultanate to kingdom, the Sultan of Egypt, Fuad I, saw his title changed to King; the kingdom's sovereignty was subject to severe limitations imposed by the British, who retained enormous control over Egyptian affairs, whose military continued to occupy the country.
Throughout the kingdom's existence Sudan was formally united with Egypt. However, actual Egyptian authority in Sudan was nominal due to Britain's role as the dominant power in Anglo-Egyptian Sudan. During the reign of King Fuad, the monarchy struggled with the Wafd Party, a broadly based nationalist political organization opposed to British domination, with the British themselves, who were determined to maintain control over the Suez Canal. Other political forces emerging in this period included the Communist Party, the Muslim Brotherhood, which became a potent political and religious force. King Fuad died in 1936 and Farouk inherited the throne at the age of sixteen. Alarmed by Italy's recent invasion of Abyssinia, he signed the Anglo-Egyptian Treaty, requiring Britain to withdraw all troops from Egypt, except in the Suez Canal Zone; the kingdom was plagued by corruption, its citizens saw it as a puppet of the British. This, coupled with the defeat in the 1948-1949 Palestine War, led to the Egyptian Revolution of 1952 by the Free Officers Movement.
Farouk abdicated in favour of his infant son Fuad II. In 1953 the monarchy was formally abolished and the Republic of Egypt was established; the legal status of Sudan was only resolved in 1954, when Egypt and Britain agreed that it should be granted independence in 1956. In 1914, Khedive Abbas II sided with the Ottoman Empire and the Central Powers in the First World War, was promptly deposed by the British in favor of his uncle Hussein Kamel. Ottoman sovereignty over Egypt, hardly more than a legal fiction since 1805, now was terminated, Hussein Kamel was declared Sultan of Egypt, the country became a British Protectorate. A group known as the Wafd attended the Paris Peace Conference of 1919 to demand Egypt's independence. Included in the group was political leader, Saad Zaghlul, who would become Prime Minister; when the group was arrested and deported to the island of Malta, a huge uprising occurred in Egypt. From March to April 1919, there were mass demonstrations; this is known in Egypt as the First Revolution.
British repression of the anti-occupation riots led to the death of some 800 people. In November 1919, the Milner Commission was sent to Egypt by the British to attempt to resolve the situation. In 1920, Lord Milner submitted his report to Lord Curzon, the British Foreign Secretary, recommending that the protectorate should be replaced by a treaty of alliance; as a result, Curzon agreed to receive an Egyptian mission headed by Zaghlul and Adli Pasha to discuss the proposals. The mission arrived in London in June 1920 and the agreement was concluded in August 1920. In February 1921, the British Parliament approved the agreement and Egypt was asked to send another mission to London with full powers to conclude a definitive treaty. Adli Pasha led this mission, which arrived in June 1921. However, the Dominion delegates at the 1921 Imperial Conference had stressed the importance of maintaining control over the Suez Canal Zone and Curzon could not persuade his Cabinet colleagues to agree to any terms that Adli Pasha was prepared to accept.
The mission returned to Egypt in disgust. In December 1921, the British authorities in Cairo imposed martial law and once again deported Zaghlul. Demonstrations again led to violence. In deference to the growing nationalism and at the suggestion of the High Commissioner, Lord Allenby, the UK recognized Egyptian independence in 1922, abolishing the protectorate, converting the Sultanate of Egypt into the Kingdom of Egypt. Sarwat Pasha became prime minister. British influence, continued to dominate Egypt's political life and fostered fiscal and governmental reforms. Britain retained control of the Canal Zone and Egypt's external protection' the police, the railways and communications' the protection of foreign interests and the Sudan pending a final agreement. Representing the Wafd Party, Zaghlul was elected Prime Minister in 1924, he demanded that Britain recognize the Egyptian sovereignty in Sudan and the unity of the Nile Valley. On November 19, 1924, the British Governor-General of Sudan, Sir Lee Stack, was assassinated in Cairo and pro-Egyptian riots broke out in Sudan.
The British demanded that Egypt withdraw troops from Sudan. Zaghlul resigned. With nationalist sentiment rising, Britain formally recognized Egyptian independence in 1922, Hussein Kamel's successor, Sultan Fuad I, substituted the title of King for Sultan. However, British occupation and interference in Egyptian affai
The Priestley Medal is the highest honor conferred by the American Chemical Society and is awarded for distinguished service in the field of chemistry. Established in 1922, the award is named after Joseph Priestley, the discoverer of oxygen who immigrated to the United States of America in 1794; the ACS formed in 1876, spearheaded by a group of chemists who had met two years in Priestley's home. The Priestley Medal is awarded to scientists who are advanced in their fields, as it is intended to commemorate lifetime achievement; when the ACS started presenting the Priestley Medal in 1923, they intended to award it every three years. This continued until 1944. 1920s1923 Ira Remsen 1926 Edgar Fahs Smith 1929 Francis P. Garvan1930s1932 Charles L. Parsons 1935 William A. Noyes 1938 Marston T. Bogert1940s1941 Thomas Midgley, Jr. 1944 James Bryant Conant 1945 Ian Heilbron 1946 Roger Adams 1947 Warren K. Lewis 1948 Edward R. Weidlein 1949 Arthur B. Lamb1950s1950 Charles A. Kraus 1951 E. J. Crane 1952 Samuel C.
Lind 1953 Sir Robert Robinson 1954 W. Albert Noyes, Jr. 1955 Charles A. Thomas 1956 Carl S. Marvel 1957 Farrington Daniels 1958 Ernest H. Volwiler 1959 Hermann Irving Schlesinger1960s1960 Wallace R. Brode 1961 Louis Plack Hammett 1962 Joel H. Hildebrand 1963 Peter J. W. Debye 1964 John C. Bailar, Jr. 1965 William J. Sparks 1966 William O. Baker 1967 Ralph Connor 1968 William G. Young 1969 Kenneth S. Pitzer1970s1970 Max Tishler 1971 Frederick D. Rossini 1972 George B. Kistiakowsky 1973 Harold C. Urey 1974 Paul J. Flory 1975 Henry Eyring 1976 George S. Hammond 1977 Henry Gilman 1978 Melvin Calvin 1979 Glenn T. Seaborg1980s1980 Milton Harris 1981 Herbert C. Brown 1982 Bryce Crawford, Jr. 1983 Robert S. Mulliken 1984 Linus Pauling 1985 Henry Taube 1986 Karl A. Folkers 1987 John D. Roberts 1988 Frank H. Westheimer 1989 George C. Pimentel1990s1990 Roald Hoffmann 1991 Harry B. Gray 1992 Carl Djerassi 1993 Robert W. Parry 1994 Howard E. Simmons 1995 Sir Derek H. R. Barton 1996 Ernest L. Eliel 1997 Mary L.
Good 1998 F. Albert Cotton 1999 Ronald Breslow2000s2000 Darleane C. Hoffman 2001 Fred Basolo 2002 Allen J. Bard 2003 Edwin J. Vandenberg 2004 Elias J. Corey 2005 George A. Olah 2006 Paul S. Anderson 2007 George M. Whitesides 2008 Gabor A. Somorjai 2009 M. Frederick Hawthorne2010s2010 Richard Zare 2011 Ahmed H. Zewail 2012 Robert S. Langer 2013 Peter J. Stang 2014 Stephen J. Lippard 2015 Jacqueline Barton 2016 Mostafa El-Sayed 2017 Tobin J. Marks 2018 Geraldine L. Richmond 2019 Karl Barry Sharpless Charles L. Parsons. "Priestley memorial and medal". Journal of Chemical Education. 9: 643. Bibcode:1932JChEd...9..643P. Doi:10.1021/ed009p643. The Priestley Society
National Academy of Sciences
The National Academy of Sciences is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences and Medicine, along with the National Academy of Engineering and the National Academy of Medicine; as a national academy, new members of the organization are elected annually by current members, based on their distinguished and continuing achievements in original research. Election to the National Academy is one of the highest honors in the scientific field. Members serve pro bono as "advisers to the nation" on science and medicine; the group holds a congressional charter under Title 36 of the United States Code. Founded in 1863 as a result of an Act of Congress, approved by Abraham Lincoln, the NAS is charged with "providing independent, objective advice to the nation on matters related to science and technology. … to provide scientific advice to the government'whenever called upon' by any government department. The Academy receives no compensation from the government for its services."
As of 2016, the National Academy of Sciences includes about 2,350 members and 450 foreign associates. It employed about 1,100 staff in 2005; the current members annually elect new members for life. Up to 84 members who are US citizens are elected every year. 190 members have won a Nobel Prize. By its own admission in 1989, the addition of women to the Academy "continues at a dismal trickle", at which time there were 1,516 male members and 57 female members; the National Academy of Sciences is a member of the International Council for Science. The ICSU Advisory Committee, in the Research Council's Office of International Affairs, facilitates participation of members in international scientific unions and serves as a liaison for U. S. national committees for individual scientific unions. Although there is no formal relationship with state and local academies of science, there is informal dialogue; the National Academy is governed by a 17-member Council, made up of five officers and 12 Councilors, all of whom are elected from among the Academy membership.
About 85 percent of funding comes from the federal government through contracts and grants from agencies and 15 percent from state governments, private foundations, industrial organizations, funds provided by the Academies member organizations. The Council has the ability ad-hoc to delegate certain tasks to committees. For example, the Committee on Animal Nutrition has produced a series of Nutrient requirements of domestic animals reports since at least 1944, each one being initiated by a different sub-committee of experts in the field for example on dairy cattle; the National Academy of Sciences meets annually in Washington, D. C., documented in the Proceedings of the National Academy of Sciences, its scholarly journal. The National Academies Press is the publisher for the National Academies, makes more than 5,000 publications available on its website. From 2004 to 2017, the National Academy of Sciences administered the Marian Koshland Science Museum to provide public exhibits and programming related to its policy work.
The museum's exhibits focused on infectious disease. In 2017 the museum closed and made way for a new science outreach program called LabX; the National Academy of Sciences maintains multiple buildings around the United States. The National Academy of Sciences Building is located at 2101 Constitution Avenue, in northwest Washington, D. C.. S. State Department; the building has a neoclassical architectural style and was built by architect Bertram Grosvenor Goodhue. The building is listed on the National Register of Historic Places. Goodhue engaged a team of artists and architectural sculptors including Albert Herter, Lee Lawrie, Hildreth Meiere to design interior embellishments celebrating the history and significance of science; the building is used for lectures, symposia and concerts, in addition to annual meetings of the NAS, NAE, NAM. The 2012 Presidential Award for Math and Science Teaching ceremony was held here on March 5, 2014. 150 staff members work at the NAS Building. In June 2012, it reopened to visitors after a major two-year restoration project which restored and improved the building's historic spaces, increased accessibility, brought the building's aging infrastructure and facilities up to date.
More than 1,000 National Academies staff members work at The Keck Center of the National Academies at 500 Fifth Street in northwest Washington, D. C; the Keck Center houses the National Academies Press Bookstore. The Marian Koshland Science Museum of the National Academy of Sciences – located at 525 E St. N. W. – hosted visits from the public, school field trips, traveling exhibits, permanent science exhibits. The NAS maintains conference centers in California and Massachusetts; the Arnold and Mabel Beckman Center is located on 100 Academy Drive in Irvine, near the campus of the University of California, Irvine. The J. Erik Jonsson Conference Center located at 314 Quissett Avenue in Woods Hole, Massachusetts, is another conference facility; the Act of Incorporation, signed by President Abraham Lincoln on March 3, 1863, created the National Academy of Sciences and named 50 charter members. Many of the original NAS members came from the so-called "Scientific Lazzaroni," an informal network of phy
Yale University is a private Ivy League research university in New Haven, Connecticut. Founded in 1701, it is the third-oldest institution of higher education in the United States and one of the nine Colonial Colleges chartered before the American Revolution. Chartered by Connecticut Colony, the "Collegiate School" was established by clergy to educate Congregational ministers, it moved to New Haven in 1716 and shortly after was renamed Yale College in recognition of a gift from British East India Company governor Elihu Yale. Restricted to theology and sacred languages, the curriculum began to incorporate humanities and sciences by the time of the American Revolution. In the 19th century, the college expanded into graduate and professional instruction, awarding the first Ph. D. in the United States in 1861 and organizing as a university in 1887. Its faculty and student populations grew after 1890 with rapid expansion of the physical campus and scientific research. Yale is organized into fourteen constituent schools: the original undergraduate college, the Yale Graduate School of Arts and Sciences and twelve professional schools.
While the university is governed by the Yale Corporation, each school's faculty oversees its curriculum and degree programs. In addition to a central campus in downtown New Haven, the university owns athletic facilities in western New Haven, a campus in West Haven and forest and nature preserves throughout New England; the university's assets include an endowment valued at $29.4 billion as of October 2018, the second largest endowment of any educational institution in the world. The Yale University Library, serving all constituent schools, holds more than 15 million volumes and is the third-largest academic library in the United States. Yale College undergraduates follow a liberal arts curriculum with departmental majors and are organized into a social system of residential colleges. All members of the Faculty of Arts and Sciences—and some members of other faculties—teach undergraduate courses, more than 2,000 of which are offered annually. Students compete intercollegiately as the Yale Bulldogs in the NCAA Division I – Ivy League.
As of October 2018, 61 Nobel laureates, 5 Fields Medalists and 3 Turing award winners have been affiliated with Yale University. In addition, Yale has graduated many notable alumni, including five U. S. Presidents, 19 U. S. Supreme Court Justices, 31 living billionaires and many heads of state. Hundreds of members of Congress and many U. S. diplomats, 78 MacArthur Fellows, 247 Rhodes Scholars and 119 Marshall Scholars have been affiliated with the university. Its wealth and influence have led to Yale being reported as amoungst the most prestigious universities in the United States. Yale traces its beginnings to "An Act for Liberty to Erect a Collegiate School", passed by the General Court of the Colony of Connecticut on October 9, 1701, while meeting in New Haven; the Act was an effort to create an institution to train ministers and lay leadership for Connecticut. Soon thereafter, a group of ten Congregational ministers, Samuel Andrew, Thomas Buckingham, Israel Chauncy, Samuel Mather, Rev. James Noyes II, James Pierpont, Abraham Pierson, Noadiah Russell, Joseph Webb, Timothy Woodbridge, all alumni of Harvard, met in the study of Reverend Samuel Russell in Branford, Connecticut, to pool their books to form the school's library.
The group, led by James Pierpont, is now known as "The Founders". Known as the "Collegiate School", the institution opened in the home of its first rector, Abraham Pierson, today considered the first president of Yale. Pierson lived in Killingworth; the school moved to Saybrook and Wethersfield. In 1716, it moved to Connecticut. Meanwhile, there was a rift forming at Harvard between its sixth president, Increase Mather, the rest of the Harvard clergy, whom Mather viewed as liberal, ecclesiastically lax, overly broad in Church polity; the feud caused the Mathers to champion the success of the Collegiate School in the hope that it would maintain the Puritan religious orthodoxy in a way that Harvard had not. In 1718, at the behest of either Rector Samuel Andrew or the colony's Governor Gurdon Saltonstall, Cotton Mather contacted the successful Boston born businessman Elihu Yale to ask him for financial help in constructing a new building for the college. Through the persuasion of Jeremiah Dummer, Elihu "Eli" Yale, who had made a fortune through trade while living in Madras as a representative of the East India Company, donated nine bales of goods, which were sold for more than £560, a substantial sum at the time.
Cotton Mather suggested that the school change its name to "Yale College".. Meanwhile, a Harvard graduate working in England convinced some 180 prominent intellectuals that they should donate books to Yale; the 1714 shipment of 500 books represented the best of modern English literature, science and theology. It had a profound effect on intellectuals at Yale. Undergraduate Jonathan Edwards discovered John Locke's works and developed his original theology known as the "new divinity". In 1722 the Rector and six of his friends, who had a study group to discuss the new ideas, announced that they had given up Calvinism, become Arminians and joined the Church of England, they were returned to the colonies as missionaries for the Anglican faith. Thomas Clapp became president in 1745 and struggled to return the college to Calvinist orthodoxy, but he did not close the library. Other students found Deist books in the library. Yale was swept up by the great intellectual movements of the peri
Arabic is a Central Semitic language that first emerged in Iron Age northwestern Arabia and is now the lingua franca of the Arab world. It is named after the Arabs, a term used to describe peoples living in the area bounded by Mesopotamia in the east and the Anti-Lebanon mountains in the west, in northwestern Arabia, in the Sinai Peninsula. Arabic is classified as a macrolanguage comprising 30 modern varieties, including its standard form, Modern Standard Arabic, derived from Classical Arabic; as the modern written language, Modern Standard Arabic is taught in schools and universities, is used to varying degrees in workplaces and the media. The two formal varieties are grouped together as Literary Arabic, the official language of 26 states, the liturgical language of the religion of Islam, since the Quran and Hadith were written in Arabic. Modern Standard Arabic follows the grammatical standards of Classical Arabic, uses much of the same vocabulary. However, it has discarded some grammatical constructions and vocabulary that no longer have any counterpart in the spoken varieties, has adopted certain new constructions and vocabulary from the spoken varieties.
Much of the new vocabulary is used to denote concepts that have arisen in the post-classical era in modern times. Due to its grounding in Classical Arabic, Modern Standard Arabic is removed over a millennium from everyday speech, construed as a multitude of dialects of this language; these dialects and Modern Standard Arabic are described by some scholars as not mutually comprehensible. The former are acquired in families, while the latter is taught in formal education settings. However, there have been studies reporting some degree of comprehension of stories told in the standard variety among preschool-aged children; the relation between Modern Standard Arabic and these dialects is sometimes compared to that of Latin and vernaculars in medieval and early modern Europe. This view though does not take into account the widespread use of Modern Standard Arabic as a medium of audiovisual communication in today's mass media—a function Latin has never performed. During the Middle Ages, Literary Arabic was a major vehicle of culture in Europe in science and philosophy.
As a result, many European languages have borrowed many words from it. Arabic influence in vocabulary, is seen in European languages Spanish and to a lesser extent Portuguese, Catalan, owing to both the proximity of Christian European and Muslim Arab civilizations and 800 years of Arabic culture and language in the Iberian Peninsula, referred to in Arabic as al-Andalus. Sicilian has about 500 Arabic words as result of Sicily being progressively conquered by Arabs from North Africa, from the mid-9th to mid-10th centuries. Many of these words relate to related activities; the Balkan languages, including Greek and Bulgarian, have acquired a significant number of Arabic words through contact with Ottoman Turkish. Arabic has influenced many languages around the globe throughout its history; some of the most influenced languages are Persian, Spanish, Kashmiri, Bosnian, Bengali, Malay, Indonesian, Punjabi, Assamese, Sindhi and Hausa, some languages in parts of Africa. Conversely, Arabic has borrowed words from other languages, including Greek and Persian in medieval times, contemporary European languages such as English and French in modern times.
Classical Arabic is the liturgical language of 1.8 billion Muslims, Modern Standard Arabic is one of six official languages of the United Nations. All varieties of Arabic combined are spoken by as many as 422 million speakers in the Arab world, making it the fifth most spoken language in the world. Arabic is written with the Arabic alphabet, an abjad script and is written from right to left, although the spoken varieties are sometimes written in ASCII Latin from left to right with no standardized orthography. Arabic is a Central Semitic language related to the Northwest Semitic languages, the Ancient South Arabian languages, various other Semitic languages of Arabia such as Dadanitic; the Semitic languages changed a great deal between Proto-Semitic and the establishment of the Central Semitic languages in grammar. Innovations of the Central Semitic languages—all maintained in Arabic—include: The conversion of the suffix-conjugated stative formation into a past tense; the conversion of the prefix-conjugated preterite-tense formation into a present tense.
The elimination of other prefix-conjugated mood/aspect forms in favor of new moods formed by endings attached to the prefix-conjugation forms. The development of an internal passive. There are several features which Classical Arabic, the modern Arabic varieties, as well as the Safaitic and Hismaic inscriptions share which are unattested in any other Central Semitic language variety, including the Dadanitic and Taymanitic languages of the northern Hejaz; these features are evidence of common descent from Proto-Arabic. The following features can be reconstructed with confidence for Proto-Arabic: negative particles m *mā.