Malcolm Sim Longair is a British physicist. From 1991 to 2008 he was the Jacksonian Professor of Natural Philosophy in the Cavendish Laboratory at the University of Cambridge. Since 2016 he has been editor-in-chief of the Biographical Memoirs of Fellows of the Royal Society, he was born on 18 May 1941, educated at Morgan Academy, Scotland. He graduated in Electronic Physics from Queen's College, which became the University of Dundee, but was part of the University of St. Andrews, in 1963, he became a research student in the Radio Astronomy Group of the Cavendish Laboratory, where he completed his Ph. D. in 1967 supervised by Martin Ryle. From 1968 to 1969, he was a Royal Society Exchange Visitor to the Lebedev Institute of the USSR Academy of Sciences, where he worked with Vitaly Ginzburg and Yakov Borisovich Zel'dovich, he held a Fellowship of the Royal Commission for the Exhibition of 1851 from 1966 to 1968 and was a Fellow of Clare Hall, Cambridge from 1967 to 1980. He has held visiting professorships at the California Institute of Technology, the Institute for Advanced Study in Princeton, the Harvard-Smithsonian Center for Astrophysics and the Space Telescope Science Institute.
From 1980 to 1990, he held the joint posts of Astronomer Royal for Scotland, Regius Professor of Astronomy of the University of Edinburgh and Director of the Royal Observatory, Edinburgh. He is Vice-President of Clare Hall, Cambridge, he was Deputy Head of the Cavendish Laboratory with special responsibility for the teaching of physics from 1991 to 1997, Head of the Cavendish Laboratory from 1997 to 2005. Longair's primary research interests are in the fields of high energy astrophysics and astrophysical cosmology, he has written many articles on this work. His most recent publication is the second edition of his Theoretical Concepts in Physics, released in December 2003, his other interests include music, mountain walking, art and golf. As of 2017 he is the editor-in-chief of the Biographical Memoirs of Fellows of the Royal Society and has authored or co-authored biographies of John E. Baldwin, Vitaly Ginzburg, Brian Pippard, Geoffrey Burbidge and David J. C. MacKay. BooksHigh Energy Astrophysics: Volume 1, Particles and their Detection.
Cambridge University Press. 2011. P. 888. ISBN 0521756189. 2nd: pbk, 1992, 440pp. ISBN 0521387736 The Cosmic Century: A History of Astrophysics and Cosmology. Cambridge University Press. 2006. P. 565. ISBN 0521474361. High Energy Astrophysics: Volume 2, the Galaxy and the Interstellar Medium. Cambridge University Press. 1994. P. 412. ISBN 0521435846. Theoretical Concepts in Physics: An Alternative View of Theoretical Reasoning in Physics. Cambridge University Press. 1984. P. 384. ISBN 0521255503. Revised and enlarged 2nd edition: 2003, 588pp. ISBN 0521821266 Our Evolving Universe. Cambridge University Press. 1996. P. 384. ISBN 0521550912. Maxwell's Enduring Legacy: A Scientific History of the Cavendish Laboratory. Cambridge University Press. 2016. ISBN 9781107083691. Papers As of 2014 he had published 298 papers. Longair, Malcolm S, "Maxwell and the science of colour", Philosophical Transactions of the Royal Society A, Mathematical and engineering sciences, 366, pp. 1685–96, Bibcode:2008RSPTA.366.1685L, doi:10.1098/rsta.2007.2178, PMID 18222905During his career he supervised numerous PhD students including Jim Dunlop, Stephen Gull, Simon Lilly and John Peacock.
Longair has received numerous awards, including
Cambridge University Press
Cambridge University Press is the publishing business of the University of Cambridge. Granted letters patent by King Henry VIII in 1534, it is the world's oldest publishing house and the second-largest university press in the world, it holds letters patent as the Queen's Printer. The press mission is "to further the University's mission by disseminating knowledge in the pursuit of education and research at the highest international levels of excellence". Cambridge University Press is a department of the University of Cambridge and is both an academic and educational publisher. With a global sales presence, publishing hubs, offices in more than 40 countries, it publishes over 50,000 titles by authors from over 100 countries, its publishing includes academic journals, reference works and English language teaching and learning publications. Cambridge University Press is a charitable enterprise that transfers part of its annual surplus back to the university. Cambridge University Press is both the oldest publishing house in the world and the oldest university press.
It originated from letters patent granted to the University of Cambridge by Henry VIII in 1534, has been producing books continuously since the first University Press book was printed. Cambridge is one of the two privileged presses. Authors published by Cambridge have included John Milton, William Harvey, Isaac Newton, Bertrand Russell, Stephen Hawking. University printing began in Cambridge when the first practising University Printer, Thomas Thomas, set up a printing house on the site of what became the Senate House lawn – a few yards from where the press's bookshop now stands. In those days, the Stationers' Company in London jealously guarded its monopoly of printing, which explains the delay between the date of the university's letters patent and the printing of the first book. In 1591, Thomas's successor, John Legate, printed the first Cambridge Bible, an octavo edition of the popular Geneva Bible; the London Stationers objected strenuously. The university's response was to point out the provision in its charter to print "all manner of books".
Thus began the press's tradition of publishing the Bible, a tradition that has endured for over four centuries, beginning with the Geneva Bible, continuing with the Authorized Version, the Revised Version, the New English Bible and the Revised English Bible. The restrictions and compromises forced upon Cambridge by the dispute with the London Stationers did not come to an end until the scholar Richard Bentley was given the power to set up a'new-style press' in 1696. In July 1697 the Duke of Somerset made a loan of £200 to the university "towards the printing house and presse" and James Halman, Registrary of the University, lent £100 for the same purpose, it was in Bentley's time, in 1698, that a body of senior scholars was appointed to be responsible to the university for the press's affairs. The Press Syndicate's publishing committee still meets and its role still includes the review and approval of the press's planned output. John Baskerville became University Printer in the mid-eighteenth century.
Baskerville's concern was the production of the finest possible books using his own type-design and printing techniques. Baskerville wrote, "The importance of the work demands all my attention. Caxton would have found nothing to surprise him if he had walked into the press's printing house in the eighteenth century: all the type was still being set by hand. A technological breakthrough was badly needed, it came when Lord Stanhope perfected the making of stereotype plates; this involved making a mould of the whole surface of a page of type and casting plates from that mould. The press was the first to use this technique, in 1805 produced the technically successful and much-reprinted Cambridge Stereotype Bible. By the 1850s the press was using steam-powered machine presses, employing two to three hundred people, occupying several buildings in the Silver Street and Mill Lane area, including the one that the press still occupies, the Pitt Building, built for the press and in honour of William Pitt the Younger.
Under the stewardship of C. J. Clay, University Printer from 1854 to 1882, the press increased the size and scale of its academic and educational publishing operation. An important factor in this increase was the inauguration of its list of schoolbooks. During Clay's administration, the press undertook a sizeable co-publishing venture with Oxford: the Revised Version of the Bible, begun in 1870 and completed in 1885, it was in this period as well that the Syndics of the press turned down what became the Oxford English Dictionary—a proposal for, brought to Cambridge by James Murray before he turned to Oxford. The appointment of R. T. Wright as Secretary of the Press Syndicate in 1892 marked the beginning of the press's development as a modern publishing business with a defined editorial policy and administrative structure, it was Wright who devised the plan for one of the most distinctive Cambridge contributions to publishing—the Cambridge Histories. The Cambridge Modern History was published
A magnetic mirror, known as a magnetic trap in Russia and as a pyrotron in the US, is a type of magnetic confinement device used in fusion power to trap high temperature plasma using magnetic fields. The mirror was one of the earliest major approaches to fusion power, along with the stellarator and z-pinch machines. In a magnetic mirror, a configuration of electromagnets is used to create an area with an increasing density of magnetic field lines at either end of the confinement area. Particles approaching the ends experience an increasing force that causes them to reverse direction and return to the confinement area; this mirror effect will only occur for particles within a limited range of velocities and angles of approach, those outside the limits will escape, making mirrors inherently "leaky". An analysis of early fusion devices by Edward Teller pointed out that the basic mirror concept is inherently unstable. In 1960, Soviet researchers introduced a new "minimum-B" configuration to address this, modified by UK researchers into the "baseball coil" and by the US to "yin-yang magnet" layout.
Each of these introductions led to further increases in performance, damping out various instabilities, but required ever-large magnet systems. The tandem mirror concept, developed in the US and Russia at about the same time, offered a way to make energy-positive machines without requiring enormous magnets and power input. By the late 1970s, many of the design problems were considered solved, Lawrence Livermore Laboratory began the design of the Mirror Fusion Test Facility based on these concepts; the machine was completed in 1986, but by this time, experiments on the smaller Tandem Mirror Experiment revealed new problems. In a round of budget cuts, MFTF was mothballed, scrapped; the mirror approach has since seen less development, in favor of the tokamak, but mirror research continues today in countries like Japan and Russia. A fusion reactor concept called the Bumpy torus made use of a series of magnetic mirrors joined in a ring, it was investigated at the Oak Ridge National Laboratory until 1986.
The concept of magnetic-mirror plasma confinement was proposed in the mid-1950s independently by Gersh Budker at the Kurchatov Institute and Richard F. Post at the Lawrence Livermore National Laboratory in the US. With the formation of Project Sherwood in 1951, Post began development of a small device to test the mirror configuration; this consisted of a linear pyrex tube with magnets around the outside. The magnets were arranged in two sets, one set of small magnets spaced evenly along the length of the tube, another pair of much larger magnets at either end. In 1952 they were able to demonstrate that plasma within the tube was confined for much longer times when the mirror magnets at the end were turned on. At the time, he referred to this device as the "pyrotron". In a now-famous talk on fusion in 1954, Edward Teller noted that any device with convex magnetic field lines would be unstable, a problem today known as the flute instability; the mirror has such a configuration, but continued experiments seemed to suggest that the experimental machines were not suffering from this problem, although there were many more practical issues limiting their performance.
In Russia, the first small-scale mirror was built in 1959 at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. They saw the problem Teller had warned them about. To fix the problem, magnetic fields should ideally be concave; this was solved by M. S. Ioffe, who added a series of additional current-carrying bars inside the reactor, such that the resulting magnetic field took on the shape of a twisted bow-tie, known as the minimum-B configuration, they demonstrated that this improved the confinement times to the order of milliseconds. The mystery of why the US's simple mirrors were not seeing this problem was discovered at a meeting in 1961. Lev Artsimovich inquired how the US team had concluded they had stable plasmas lasting on the order of milliseconds; this turned out to be due to the readings of one diagnostic instrument. When Artsimovich learned they had not accounted for the measurement delay in these instruments, it became clear the US mirrors had been suffering from this problem all along.
With this discovery, "Ioffe bars" were taken up by researchers in the US, UK, Japan. A group at the Culham Centre for Fusion Energy noted that the arrangement could be improved by combining the original rings and the bars into a single new arrangement similar to the seam on a tennis ball; this concept was picked up in the US. These "baseball coils" had the great advantage that they left the internal volume of the reactor open, allowing easy access for diagnostic instruments. On the downside, the size of the magnet in comparison to the volume of plasma was inconvenient, required powerful magnets. Post introduced a further improvement, the "yin-yang coils", which used two C-shaped magnets to produce the same field configuration, but in a smaller volume. With the major instability addressed, researchers now discovered that the original leakiness of the design was far higher than expected; this was traced to a host of newly discovered "microinstabilities" that caused fuel to enter the "escape cone" of the reactor and flow out the ends of the mirror.
Suppressing these new problems filled much of the 1960s. By the late 1960s, magnetic mirror confinement was considered a viable technique for producing fusion energy. In the United States, efforts were funded under the United States Atomic Energy Commissions' Project Sherwood. A machine design was first published in 1967; the concept w
A solar flare is a sudden flash of increased brightness on the Sun observed near its surface and in close proximity to a sunspot group. Powerful flares are but not always, accompanied by a coronal mass ejection; the most powerful flares are detectable in the total solar irradiance. Solar flares occur in a power-law spectrum of magnitudes. Flares are associated with the ejection of plasmas and particles through the Sun's corona into outer space. If the ejection is in the direction of the Earth, particles associated with this disturbance can penetrate into the upper atmosphere and cause bright auroras, may disrupt long range radio communication, it takes days for the solar plasma ejecta to reach Earth. Flares occur on other stars, where the term stellar flare applies. High-energy particles, which may be relativistic, can arrive simultaneously with the electromagnetic radiations. On July 23, 2012, a massive damaging, solar storm missed Earth. According to NASA, there may be as much as a 12% chance of a similar event occurring between 2012 and 2022.
Solar flares affect all layers of the solar atmosphere. The plasma medium is heated to tens of millions of kelvins, while electrons and heavier ions are accelerated to near the speed of light. Flares produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths, from radio waves to gamma rays. Most of the energy is spread over frequencies outside the visual range and so the majority of the flares are not visible to the naked eye and must be observed with special instruments. Flares occur in active regions around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by the sudden release of magnetic energy stored in the corona; the same energy releases may produce coronal mass ejections, although the relationship between CMEs and flares is still not well understood. X-rays and UV radiation emitted by solar flares can affect Earth's ionosphere and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb the operation of radars and other devices that use those frequencies.
Solar flares were first observed on the Sun by Richard Christopher Carrington and independently by Richard Hodgson in 1859 as localized visible brightenings of small areas within a sunspot group. Stellar flares can be inferred by looking at the lightcurves produced from the telescope or satellite data of variety of other stars; the frequency of occurrence of solar flares varies, from several per day when the Sun is "active" to less than one every week when the Sun is "quiet", following the 11-year cycle. Large flares are less frequent than smaller ones. Flares occur when accelerated charged particles electrons, interact with the plasma medium. Evidence suggests that the phenomenon of magnetic reconnection leads to this copious acceleration of charged particles. On the Sun, magnetic reconnection may happen on solar arcades – a series of occurring loops following magnetic lines of force; these lines of force reconnect into a lower arcade of loops leaving a helix of magnetic field unconnected to the rest of the arcade.
The sudden release of energy in this reconnection is the origin of the particle acceleration. The unconnected magnetic helical field and the material that it contains may violently expand outwards forming a coronal mass ejection; this explains why solar flares erupt from active regions on the Sun where magnetic fields are much stronger. Although there is a general agreement on the source of a flare's energy, the mechanisms involved are still not well understood, it is not clear how the magnetic energy is transformed into the kinetic energy of the particles, nor is it known how some particles can be accelerated to the GeV range and beyond. There are some inconsistencies regarding the total number of accelerated particles, which sometimes seems to be greater than the total number in the coronal loop. Scientists are unable to forecast flares; the classification system for solar flares uses the letters A, B, C, M or X, according to the peak flux in watts per square metre of X-rays with wavelengths 100 to 800 picometre, as measured at the Earth by the GOES spacecraft.
The strength of an event within a class is noted by a numerical suffix ranging from 1 to 9, the factor for that event within the class. Hence, an X2 flare is twice the strength of an X1 flare, an X3 flare is three times as powerful as an X1, only 50% more powerful than an X2. An X2 is four times more powerful than an M5 flare. An earlier flare classification was based on Hα spectral observations; the scheme uses emitting surface. The classification in intensity is qualitative, referring to the flares as: faint, normal or brilliant; the emitting surface is described below. A flare is classified taking S or a number that represents its size and a letter that represents its peak intensity, v.g.: Sn is a normal sunflare. Solar flares influence the local space weather in the vicinity of the Earth, they can produce streams of energetic particles in the solar wind or stellar wind, known as a solar proton event. These particles
A supernova remnant is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, consists of ejected material expanding from the explosion, the interstellar material it sweeps up and shocks along the way. There are two common routes to a supernova: either a massive star may run out of fuel, ceasing to generate fusion energy in its core, collapsing inward under the force of its own gravity to form a neutron star or a black hole. In either case, the resulting supernova explosion expels much or all of the stellar material with velocities as much as 10% the speed of light; these ejecta are supersonic: assuming a typical temperature of the interstellar medium of 10,000 K, the Mach number can be > 1000. Therefore, a strong shock wave forms ahead of the ejecta, that heats the upstream plasma up to temperatures well above millions of K; the shock continuously slows down over time as it sweeps up the ambient medium, but it can expand over hundreds or thousands of years and over tens of parsecs before its speed falls below the local sound speed.
One of the best observed young supernova remnants was formed by SN 1987A, a supernova in the Large Magellanic Cloud, observed in February 1987. Other well-known supernova remnants include the Crab Nebula; the youngest known remnant in our galaxy is G1.9+0.3, discovered in the galactic center. An SNR passes through the following stages as it expands: Free expansion of the ejecta, until they sweep up their own weight in circumstellar or interstellar medium; this can last tens to a few hundred years depending on the density of the surrounding gas. Sweeping up of a shell of shocked circumstellar and interstellar gas; this begins the Sedov-Taylor phase. Strong X-ray emission traces the strong shock waves and hot shocked gas. Cooling of the shell, to form a thin, dense shell surrounding the hot interior; this is the pressure-driven snowplow phase. The shell can be seen in optical emission from recombining ionized hydrogen and ionized oxygen atoms. Cooling of the interior; the dense shell continues to expand from its own momentum.
This stage is best seen in the radio emission from neutral hydrogen atoms. Merging with the surrounding interstellar medium; when the supernova remnant slows to the speed of the random velocities in the surrounding medium, after 30,000 years, it will merge into the general turbulent flow, contributing its remaining kinetic energy to the turbulence. There are three types of supernova remnant: Shell-like, such as Cassiopeia A Composite, in which a shell contains a central pulsar wind nebula, such as G11.2-0.3 or G21.5-0.9. Mixed-morphology remnants, in which central thermal X-ray emission is seen, enclosed by a radio shell; the thermal X-rays are from swept-up interstellar material, rather than supernova ejecta. Examples of this class include the SNRs W28 and W44. Supernova remnants are considered the major source of galactic cosmic rays; the connection between cosmic rays and supernovas was first suggested by Walter Baade and Fritz Zwicky in 1934. Vitaly Ginzburg and Sergei Syrovatskii in 1964 remarked that if the efficiency of cosmic ray acceleration in supernova remnants is about 10 percent, the cosmic ray losses of the Milky Way are compensated.
This hypothesis is supported by a specific mechanism called "shock wave acceleration" based on Enrico Fermi's ideas, still under development. Indeed, Enrico Fermi proposed in 1949 a model for the acceleration of cosmic rays through particle collisions with magnetic clouds in the interstellar medium; this process, known as the "Second Order Fermi Mechanism", increases particle energy during head-on collisions, resulting in a steady gain in energy. A model to produce Fermi Acceleration was generated by a powerful shock front moving through space. Particles that cross the front of the shock can gain significant increases in energy; this became known as the "First Order Fermi Mechanism". Supernova remnants can provide the energetic shock fronts required to generate ultra-high energy cosmic rays. Observation of the SN 1006 remnant in the X-ray has shown synchrotron emission consistent with it being a source of cosmic rays. However, for energies higher than about 1018 eV a different mechanism is required as supernova remnants cannot provide sufficient energy.
It is still unclear. The future telescope CTA will help to answer this question. List of All Known Galactic and Extragalactic Supernovae on the Open Supernova Catalog Galactic SNR Catalogue Chandra observations of supernova remnants: catalog, photo album, selected picks 2MASS images of Supernova Remnants NASA: Introduction to Supernova Remnants NASA's Imagine: Supernova Remnants Afterlife of a Supernova on UniverseToday.com Supernova remnant on arxiv.org Supernova Remnants, SEDS
International Standard Serial Number
An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is helpful in distinguishing between serials with the same title. ISSN are used in ordering, interlibrary loans, other practices in connection with serial literature; the ISSN system was first drafted as an International Organization for Standardization international standard in 1971 and published as ISO 3297 in 1975. ISO subcommittee TC 46/SC 9 is responsible for maintaining the standard; when a serial with the same content is published in more than one media type, a different ISSN is assigned to each media type. For example, many serials are published both in electronic media; the ISSN system refers to these types as electronic ISSN, respectively. Conversely, as defined in ISO 3297:2007, every serial in the ISSN system is assigned a linking ISSN the same as the ISSN assigned to the serial in its first published medium, which links together all ISSNs assigned to the serial in every medium.
The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers. As an integer number, it can be represented by the first seven digits; the last code digit, which may be 0-9 or an X, is a check digit. Formally, the general form of the ISSN code can be expressed as follows: NNNN-NNNC where N is in the set, a digit character, C is in; the ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, C=5. To calculate the check digit, the following algorithm may be used: Calculate the sum of the first seven digits of the ISSN multiplied by its position in the number, counting from the right—that is, 8, 7, 6, 5, 4, 3, 2, respectively: 0 ⋅ 8 + 3 ⋅ 7 + 7 ⋅ 6 + 8 ⋅ 5 + 5 ⋅ 4 + 9 ⋅ 3 + 5 ⋅ 2 = 0 + 21 + 42 + 40 + 20 + 27 + 10 = 160 The modulus 11 of this sum is calculated. For calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, counting from the right.
The modulus 11 of the sum must be 0. There is an online ISSN checker. ISSN codes are assigned by a network of ISSN National Centres located at national libraries and coordinated by the ISSN International Centre based in Paris; the International Centre is an intergovernmental organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, the ISDS Register otherwise known as the ISSN Register. At the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept. An ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an anonymous identifier associated with a serial title, containing no information as to the publisher or its location. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change. Since the ISSN applies to an entire serial a new identifier, the Serial Item and Contribution Identifier, was built on top of it to allow references to specific volumes, articles, or other identifiable components.
Separate ISSNs are needed for serials in different media. Thus, the print and electronic media versions of a serial need separate ISSNs. A CD-ROM version and a web version of a serial require different ISSNs since two different media are involved. However, the same ISSN can be used for different file formats of the same online serial; this "media-oriented identification" of serials made sense in the 1970s. In the 1990s and onward, with personal computers, better screens, the Web, it makes sense to consider only content, independent of media; this "content-oriented identification" of serials was a repressed demand during a decade, but no ISSN update or initiative occurred. A natural extension for ISSN, the unique-identification of the articles in the serials, was the main demand application. An alternative serials' contents model arrived with the indecs Content Model and its application, the digital object identifier, as ISSN-independent initiative, consolidated in the 2000s. Only in 2007, ISSN-L was defined in the
Tony Bell (physicist)
Anthony Raymond Bell is Professor of Physics at the University of Oxford and the Rutherford Appleton Laboratory. Bell was educated at the University of Cambridge where he was awarded a PhD in radio astronomy in 1977 for research investigating supernova remnants. Following his PhD, Bell worked on radar signal processing with Marconi Electronic Systems before moving to the Central Laser Facility as a laser-plasma theorist. In 1985 he was appointed a lecturer at Imperial College London. In 2007, following two years with the Methodist Church, he was jointly appointed at the Clarendon Laboratory and the Central Laser Facility. Bell's research investigates plasma physics, he wrote one of four independent papers proposing the theory of cosmic ray acceleration by shocks. He showed how strong magnetic field is generated during particle acceleration and how it enables cosmic ray acceleration to high energy, he initiated the theory of non-local transport for heat flow in inertial confinement fusion, explained the collimation of laser-produced energetic electrons by resistively generated magnetic field, with John G. Kirk demonstrated the possibility of electron-positron pair production in ultra-high intensity laser-plasma interactions.
Bell was awarded the 2014 Hoyle Medal and Prize of the Institute of Physics "for elucidating the origin and impact of cosmic rays and for his seminal contributions to electron energy transport in laboratory plasmas". In 2016 he was awarded the Eddington Medal of the Royal Astronomical Society for "his development of the theory of the acceleration of charged particles in astrophysics, known as Diffusive Shock Acceleration", he was elected a Fellow of the Royal Society in 2017