Algol, designated Beta Persei, known colloquially as the Demon Star, is a bright multiple star in the constellation of Perseus and one of the first non-nova variable stars to be discovered. Algol is a three-star system, consisting of Beta Persei Aa1, Aa2, Ab – in which the hot luminous primary β Persei Aa1 and the larger, but cooler and fainter, β Persei Aa2 pass in front of each other, causing eclipses, thus Algol's magnitude is near-constant at 2.1, but dips to 3.4 every 2.86 days during the 10-hour-long partial eclipses. The secondary eclipse when the brighter primary star occults the fainter secondary is shallow and can only be detected photoelectrically. Algol gives its name to its class of eclipsing variable, known as Algol variables. An Ancient Egyptian Calendar of Lucky and Unlucky Days composed some 3,200 years ago is claimed to be the oldest historical document of the discovery of Algol; the association of Algol with a demon-like creature suggests that its variability was known long before the 17th century, but there is still no indisputable evidence for this.
The Arabic astronomer al-Sufi said nothing about any variability of the star in his Book of Fixed Stars published c.964. The variability of Algol was noted in 1667 by Italian astronomer Geminiano Montanari, but the periodic nature of its variations in brightness was not recognized until more than a century when the British amateur astronomer John Goodricke proposed a mechanism for the star's variability. In May 1783, he presented his findings to the Royal Society, suggesting that the periodic variability was caused by a dark body passing in front of the star. For his report he was awarded the Copley Medal. In 1881, the Harvard astronomer Edward Charles Pickering presented evidence that Algol was an eclipsing binary; this was confirmed a few years in 1889, when the Potsdam astronomer Hermann Carl Vogel found periodic doppler shifts in the spectrum of Algol, inferring variations in the radial velocity of this binary system. Thus Algol became one of the first known spectroscopic binaries. Joel Stebbins at the University of Illinois Observatory used an early selenium cell photometer to produce the first-ever photoelectric study of a variable star.
The light curve revealed the reflection effect between the two stars. Some difficulties in explaining the observed spectroscopic features led to the conjecture that a third star may be present in the system. Listed are the first eclipse times of each month. Β Persei Aa2 eclipses β Persei Aa1 every 2.867321 days. For example, the Jan 2, 20h, eclipse will yield consecutive eclipse times on Jan 5, 17h Jan 8, 16h Jan 11, 13h, etc.. Algol is a triple-star system. From the point of view of the Earth, Algol Aa1 and Algol Aa2 form an eclipsing binary because their orbital plane contains the line of sight to the Earth; the eclipsing binary pair is separated by only 0.062 astronomical units from each other, whereas the third star in the system is at an average distance of 2.69 au from the pair, the mutual orbital period of the trio is 681 Earth days. The total mass of the system is about 5.8 solar masses, the mass ratios of Aa1, Aa2, Ab are about 4.5 to 1 to 2. The three components of the bright triple star used to be, still sometimes are, referred to as β Per A, B, C.
The Washington Double Star Catalog lists them as Aa1, Aa2, Ab, with two faint stars B and C about one arcmin distant. A further five faint stars are listed as companions. Studies of Algol led to the Algol paradox in the theory of stellar evolution: although components of a binary star form at the same time, massive stars evolve much faster than the less massive stars, the more massive component Algol A is still in the main sequence, but the less massive Algol B is a subgiant star at a evolutionary stage; the paradox can be solved by mass transfer: when the more massive star became a subgiant, it filled its Roche lobe, most of the mass was transferred to the other star, still in the main sequence. In some binaries similar to Algol, a gas flow can be seen; the gas flow between the primary and secondary stars in Algol has been imaged using Doppler Tomography. This system exhibits x-ray and radio wave flares; the x-ray flares are thought to be caused by the magnetic fields of the A and B components interacting with the mass transfer.
The radio-wave flares might be created by magnetic cycles similar to those of sunspots, but because the magnetic fields of these stars are up to ten times stronger than the field of the Sun, these radio flares are more powerful and more persistent. The secondary component was identifed as the radio emitting source in Algol using Very-long-baseline interferometry by Lestrade and co-authors. Magnetic activity cycles in the chromospherically active secondary component induce changes in its radius of gyration that have been linked to recurrent orbital period variations on the order of ΔP/P ≈ 10−5 via the Applegate mechanism. Mass transfer between the components is small in the Algol system but could be a significant source of period change in other Algol-type binaries. Algol is about 92.8 light-years from the Sun, but about 7.3 million years ago it passed within 9.8 light-years of the Solar System and its apparent magnitude was about −2.5, brighter than the star Sirius is today. Because the t
George Britton Halford was an English-born anatomist and physiologist, founder of the first medical school in Australia, University of Melbourne School of Medicine. Halford was born in Petworth, England, second son of James Halford, a merchant of Haverstock Hill, his wife Nancy, née Gadd. Halford began studying medicine in 1842, became a member of the Royal College of Physicians in 1851, of the Royal College of Surgeons in 1852, he obtained his doctorate of medicine at University of St Andrews in 1854. After practising at Liverpool, he was in 1857 appointed lecturer in anatomy at the Grosvenor Place school of medicine, London; when applications were called for the professorship of anatomy and pathology at the University of Melbourne in 1862, he was described as "one of the most distinguished experimental physiologists of the day". There were other good candidates, but Halford was appointed, he arrived in Melbourne on 22 December 1862. A medical curriculum had been drawn up by the council for which the vice-chancellor, Dr Anthony Brownless, was responsible.
This course was longer by a year than any systematic course of medical education existing in Great Britain or Ireland. Thirty years passed before the general medical council implied on a minimum five-year course in the United Kingdom. Halford began teaching with only three students which in the next 15 years increased to about 70, his task indeed was only made possible by the comparatively small classes in those early years. He was offered the fellowship of the Royal College of Physicians in 1870 but never went in, he had in the meantime done some research work in comparative anatomy, had begun his work on the poison of snakes which he continued for many years. As Halford neared 60 years, he began to feel the strain of his combined offices, but the appointment of a brilliant young assistant, Harry Brookes Allen, who became lecturer in anatomy and pathology in 1882, must have made his position easier. Allen became professor of descriptive and surgical anatomy and pathology in 1883, Halford took the title of professor of general anatomy and histology.
Though easing down in his work to some extent, he was still a great influence with the students. Sir Richard Stawell, who graduated in 1898, has testified that "there was something always really'great' about the old professor. In September 1896 Halford was given leave of absence on account of ill-health until the end of 1897; this leave was afterwards extended and he did not become emeritus professor until 1900. After his retirement he lived at Beaconsfield near Melbourne and was much interested in the development of coal-mining in South Gippsland, he celebrated his golden wedding in 1907 and died at Inverloch, Victoria, on 27 May 1910. He was survived by six sons, two of whom entered the medical profession. In 1928 his family founded the Halford Oration at the Australian Institute of Canberra. A list of Halford's contributions to medical literature can be found in the Medical Journal of Australia for 19 January 1929, page 71. Halford was a creationist, he challenged the views of T. H. Huxley, he argued that apes shared no common ancestor.
In his book on snake venom he wrote that the snake had been designed by "some omnipotent power with infinite will." On the Time and Manner of Closure of the Auriculo-Ventricular Valves Not Like Man and Biped, nor yet Quadrumanous, but Cheiropodous Lines of Demarcation Between Man, Gorilla, & Macaque Thoughts and Experiments on the Action of Snake Venom on the Blood Royal College of Physicians K. F. Russell,'Halford, George Britton', Australian Dictionary of Biography, Volume 4, MUP, 1972, pp 321–322. Retrieved 3 January 2009 Serle, Percival. "Halford, George Britton". Dictionary of Australian Biography. Sydney: Angus and Robertson. Retrieved 2009-01-03. Barry Butcher.. Gorilla Warfare in Melbourne: Halford and Man's Place in Nature. In R. W. Home. Australian Science in the Making. Cambridge University Press. Pp. 153-167. ISBN 0-521-39640-9
Pinduoduo is an e-commerce platform allowing users to participate in group buying deals. It was founded by Colin Huang as Shanghai Dream Information Technology Co. Ltd. in September 2015. The company was founded in September 2015. In July 2016, Tencent and Xintianyu invested more than US$110 million in the B round. By 2018, the number of users had exceeded 200 million, GMV had exceeded 100 billion yuan, the daily order volume ranked second in mainland China only after Taobao. On July 26, 2018, the company was listed on the NASDAQ stock market in the United States under the ticker symbol PDD; the IPO price was $19. It raised US$1.6 billion, making it one of the largest IPOs of 2018. In February 2019, the company announced a public sale of more than US$1 billion of additional shares. On June 7, 2018, China Legal Evening News reported that "there are many illegal and violent goods involved in the law," and you can buy cheap goods, there are many commodities that involve pornography and illegal activities.
Including the blade knife, pseudo base station device, motorcycle license plate and inflatable doll, etc. On January 20, 2019, the company reported theft of online discount vouchers worth tens of millions of yuan. An online collective of users exploited a loophole in Pinduoduo's system and stole tens of millions of yuan worth of discount vouchers; the company notified the police about the incident. Official website
James Hyman is a DJ, Radio & TV presenter, Music Supervisor and founder of The Hyman Archive. Hyman put aside his place at University of Manchester to work at MTV Europe in the Press office, despite his parents' misgivings. For over 25 years, Hyman has been collecting magazines, newsletters, brochures and other printed material; the theme of Hyman's collecting is'popular culture in print'. He began collecting to assist his research at MTV Europe, where he was a script writer and programme producer; this was in a period where, according to Hyman, "magazines were the internet". HYMAG contains over 5,000 individual title publications and over 120,000 individual issues as of February 2020. On 1 August 2012, Guinness World Records verified that, "The largest collection of magazines consists of 50,953 magazines and belongs to James Hyman, in London, UK". At that time, the collection featured 2,312 unique publications amongst the 50,953 magazines; the process of counting the magazines took 128 days as James and Tory Turk worked their way through 450 crates filled with magazines.
In September 2014, with an investor, Hyman formed The Hyman Archive Ltd. in order to obtain an ECL with copyright holders contained within the collection, to digitise and meta-tag the collection, making it available in a commercial offering. Hyman hopes to have secured an ECL by Spring 2016; the company will begin the process of digitising the collection's approximate 10 million pages. Hyman worked at MTV Europe, as a Press Officer as a programmer and director, his MTV shows, including Party Zone featured in-depth interviews with the likes of The Prodigy, Moby, David Holmes, The Chemical Brothers, Paul Oakenfold, Aphex Twin. Hyman co-presented MTV's Up For It and fronted a spin-off from MTV's Bytesize programme, providing daily reports on Internet news & web sites. In 1992 with Coldcut produced a TV Megamix for Canal+ weekly pop-culture show, pre-empting his MTV Megamix format and shows that began broadcast on MTV Europe in 1998. Presented on Atlantic 252 and Xfm London as producer / presenter of The Rinse & co-presenter / producer of The Remix, the latter nominated for 2003 Sony Radio Academy Award.
The Rinse focused on Dance music with Hyman championing other emerging music trends such as Bastard pop. The Remix focused on mash-up remixes and, according to The Guardian, "led the craze" which caused some controversy when a cease and desist order was issued for playing "A Stroke of Genius" by The Freelance Hellraiser; the Xfm shows paved the way for the release of a number of albums: The Remix and The Remix 2 Covered 8 themed mix CDs including: Pulp Mixin' which remixed the work of Quentin Tarantino and Licence To Thrill, an audio homage to James Bond, which featured in The Daily Telegraph's top 5 CDs of 2004 September 2007, Hyman left Xfm to concentrate on his music supervision company JLH and other broadcast projects. A one-hour documentary about Paul Anka and his song "My Way" was produced by Hyman and Nick Minter as part of BBC Radio 2's series, "Song Stories", first broadcast 23 February 2011, it was presented by Michael Buble and featured interviews with David Bowie, Donald Trump, Julien Temple and Steve Wynn on BBC Radio 2.
Hyman expanded his Quentin Tarantino mix tape, Pulp Mixin', to create a feature-length mash-up film, with the provisional title James Hyman/Quentin Tarantino Movie Mash-Up. It blends Tarantino's film footage with music videos, including those of the music used in the films. James Hyman – official site James Hyman discography at Discogs James Hyman on IMDb
Merrie Melodies Starring Bugs Bunny & Friends is an animated anthology television series that aired weekdays in syndication from 1990 to 1992 and on the Fox Kids Network from 1992 to 1994. Made to coincide with Bugs Bunny's 50th birthday and the debut of Tiny Toon Adventures, the series featured cartoons from the Looney Tunes and Merrie Melodies library and was distributed by Warner Bros. Domestic Television Distribution; this series is not to be confused with Warners' earlier syndicated anthology The Merrie Melodies Show. For the syndicated version of the series, each episode began with a title sequence, directed by Darrell Van Citters, featuring Bugs Bunny and Daffy Duck showing classic cartoon clips on a screen; the show itself ran for a half-hour and contained three classic shorts, one of them starring Bugs Bunny, with a short "Hip Clip" placed in between the second and third shorts. 65 episodes of Merrie Melodies were created and aired in first-run syndication from September 17 to December 14, 1990.
Merrie Melodies moved to the Fox Kids Network in September 1992, which brought forth several changes to the format. A new animated opening was produced featuring Bugs oversleeping and making a frantic run through the Warner Bros. Studios, passing by several Looney Tunes characters as he makes his way to a soundstage. An asterisk denotes a black-and-white cartoon, computer-colorized. Merrie Melodies Starring Bugs Bunny & Friends on IMDb
Polythiazyl, x, is an electrically conductive, gold- or bronze-colored polymer with metallic luster. It was the first conductive inorganic polymer discovered and was found to be a superconductor at low temperatures, it is a fibrous solid, described as "lustrous golden on the faces and dark blue-black", depending on the orientation of the sample. It is air insoluble in all solvents; the compound was first reported as early as 1910 by F. P. Burt, who obtained it by heating tetrasulfur tetranitride in vacuum over silver wool; the compound was the first non-metallic compound. However, the low transition temperature at about 0.3 K makes a practical application unlikely. Polythiazyl is a crystalline but fibrous material; the polymer is inert to oxygen and water, but decomposes in air to a grey powder. At temperatures above 240 °C explosive decomposition can occur; the compound explodes on impact. Polythiazyl shows an anisotropic electrical conductivity. Along the fibres or SN chains, the bond is electrically conductive, perpendicular to it acts as an insulator.
The one-dimensional conductivity is based on the bonding conditions in the S-N chain, where each sulfur atom provides two π electrons and each nitrogen atom provides one π electron to form two-center 3π electron bonding units. Two polymorphic crystal forms were observed in the compound; the monoclinic form I obtained from the synthesis can be converted into an orthorhombic form II by mechanical treatment such as grinding. The material is a polymer; the S and N atoms on adjacent chains align. Several resonance structures can be written; the structure of the crystalline compound was resolved by X-ray diffraction. This showed alternating SN bond lengths of 159 pm and 163 pm and SNS bond angles of 120 °C and NSN bond angles of 106 °C. Polythiazyl is synthesized by the polymerization of the dimer disulfur dinitride, in turn synthesized from the cyclic alternating tetramer tetrasulfur tetranitride. Conversion from cyclic tetramer to dimer is catalysed with hot silver wool. S4N4 + 8 Ag → 4 Ag2S + 2 N2S4N4 → 2 S2N2 → S2N2S2N2 → thermal polymerization → x Due to its electrical conductivity, polythiazyl is used in LEDs, battery cathodes, solar cells.