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45,187,642 | https://en.wikipedia.org/wiki/Clement%20W.%20H.%20Lam | Clement Wing Hong Lam () is a Canadian mathematician, specializing in combinatorics. He is famous for the computer proof, with Larry Thiel and S. Swiercz, of the nonexistence of a finite projective plane of order 10.
Lam earned his PhD in 1974 under Herbert Ryser at Caltech with thesis Rational G-Circulants Satisfying the Matrix Equation . He is a professor at Concordia University in Montreal.
In 2006 he received the Euler medal. In 1992 he received the Lester Randolph Ford Award for the article The search for a finite projective plane of order 10. The eponymous Lam's problem is equivalent to finding a finite projective plane of order 10 or finding 9 orthogonal Latin squares of order 10.
See also
Experimental mathematics
References
External links
Homepage
search on author CWH Lam from Google Scholar
Canadian mathematicians
Combinatorialists
California Institute of Technology alumni
Academic staff of Concordia University
Living people
Year of birth missing (living people)
Place of birth missing (living people) | Clement W. H. Lam | Mathematics | 201 |
78,243,420 | https://en.wikipedia.org/wiki/PNC%20Process%20Systems | PNC Process Systems (PNC; ) is a publicly listed Chinese company that engages in the development and sale of semiconductor equipment mostly notably in wet cleaning.
Background
PNC was founded in 2000 by Jiang Yuan. She was previously the marketing director at Kinetics Process Systems before leaving with her team to establish PNC.
Although the company initially experienced difficulty, according to Jiang by 2010, the company no longer required any loans or external financing.
In 2017, PNC held its initial public offering becoming a listed company on the Shanghai Stock Exchange. Around this time, PNC established its wet cleaning equipment division which became the focus of the company.
In 2019, PNC acquired optoelectronics firm, Bandweaver Technologies for 680 million yuan.
In December 2023, the United States Department of Commerce's Bureau of Industry and Security added PNC to the Unverified List.
In February 2024, The Korea Times reported four Samsung Electronics employees were arrested in the previous month for sharing the company's latest semiconductor surface cleaning equipment technology with PNC.
Customers of PNC include Samsung, SK Hynix, TSMC, SMIC, Hua Hong Semiconductor, Yangtze Memory Technologies, ChangXin Memory Technologies and Silan Microelectronics.
See also
ACM Research
Semiconductor industry in China
References
External links
2000 establishments in China
2017 initial public offerings
Companies based in Shanghai
Companies listed on the Shanghai Stock Exchange
Electronics companies established in 2000
Equipment semiconductor companies
Semiconductor companies of China | PNC Process Systems | Engineering | 298 |
25,288,599 | https://en.wikipedia.org/wiki/Milameline | Milameline (CI-979, PD-129,409, RU-35,926) is a non-selective muscarinic acetylcholine receptor partial agonist with cognition-acting properties that was being investigated for the treatment of Alzheimer's disease, but produced poor results in clinical trials and was subsequently discontinued.
Changing the O-methyl aldoxime to an O-propargyl oxime instead gives a separate molecule called RU 35986.
See also
Alvameline
Sabcomeline
Tazomeline
Xanomeline
References
Abandoned drugs
Aldoximes
M1 receptor agonists
M2 receptor agonists
M3 receptor agonists
M4 receptor agonists
M5 receptor agonists
Oxime ethers
Tetrahydropyridines | Milameline | Chemistry | 164 |
40,417,621 | https://en.wikipedia.org/wiki/Scout%20%28autonomous%20boat%29 | Scout is an autonomous robotic boat designed to complete the first autonomous transatlantic crossing. The project was started by Tiverton students Dylan Rodriguez and Max Kramers in 2010 with the goal of creating an autonomous craft to make the journey from Rhode Island to Sanlucar de Barrameda, Spain. After several iterations, Scout's first transatlantic attempt was launched from Sakonnet Point on June 29, 2013, but unfavourable weather conditions forced the team to recover the craft the same day. A second launch was made July 4, 2013 but after two days a technical failure forced another recovery effort and a redesign of parts of the vessel. The third attempt was launched during the early morning of August 24, 2013 and is currently in progress but has already earned the record for distance of an unmanned Atlantic naval voyage.
Technical specifications
Scout is based on a custom carbon fiber hull with a Divinycell foam core and measures 12.8 feet long, and 25 inches wide and weighs 160 pounds. The vessel design incorporates a bulb keel to right the craft in heavy seas, and propulsion is provided by an electric trolling motor powered by a bank of solar-charged lithium iron phosphate batteries. On-board control and navigation is provided by two Arduino microcontrollers and a GPS receiver, and telemetry data is sent back to the team using the Iridium satellite constellation and provided live on the World Wide Web.
References
External links
Scout Transatlantic
Live Tracking
Unmanned surface vehicles of the United States
Robotics | Scout (autonomous boat) | Engineering | 303 |
1,918,853 | https://en.wikipedia.org/wiki/Dimethylethanolamine | Dimethylethanolamine (DMAE or DMEA) is an organic compound with the formula . It is bifunctional, containing both a tertiary amine and primary alcohol functional groups. It is a colorless viscous liquid. It is used in skin care products for improving skin tone and
also taken orally as a nootropic. It is prepared by the ethoxylation of dimethylamine.
Industrial uses
Dimethylaminoethanol is used as a curing agent for polyurethanes and epoxy resins. It is a precursor to other chemicals, such as the nitrogen mustard 2-dimethylaminoethyl chloride. The acrylate ester, dimethylaminoethyl acrylate is used as a flocculating agent.
Related compounds are used in gas purification, e.g. removal of hydrogen sulfide from sour gas streams.
Human uses
The bitartrate salt of DMAE, i.e. N,N-dimethylethanolamine bitartrate, is sold as a dietary supplement. It is a white powder providing 37% DMAE.
Animal tests show possible benefit for improving spatial memory and working memory.
See also
Choline
Diphenhydramine
Doxylamine
Ethanolamine
Meclofenoxate (Centrophenoxine)
Orphenadrine
References
Dimethylamino compounds
Primary alcohols
Cholinergics
Nootropics
Corrosion inhibitors
Ethanolamines | Dimethylethanolamine | Chemistry | 307 |
607,864 | https://en.wikipedia.org/wiki/Sunrise%20problem | The sunrise problem can be expressed as follows: "What is the probability that the sun will rise tomorrow?" The sunrise problem illustrates the difficulty of using probability theory when evaluating the plausibility of statements or beliefs.
According to the Bayesian interpretation of probability, probability theory can be used to evaluate the plausibility of the statement, "The sun will rise tomorrow."
The sunrise problem was first introduced publicly in 1763 by Richard Price in his famous coverage of Thomas Bayes' foundational work in Bayesianism.
Laplace's approach
Pierre-Simon Laplace, who treated it by means of his rule of succession. Let p be the long-run frequency of sunrises, i.e., the sun rises on 100 × p% of days. Prior to knowing of any sunrises, one is completely ignorant of the value of p. Laplace represented this prior ignorance by means of a uniform probability distribution on p.
For instance, the probability that p is between 20% and 50% is just 30%. This must not be interpreted to mean that in 30% of all cases, p is between 20% and 50%. Rather, it means that one's state of knowledge (or ignorance) justifies one in being 30% sure that the sun rises between 20% of the time and 50% of the time. Given the value of p, and no other information relevant to the question of whether the sun will rise tomorrow, the probability that the sun will rise tomorrow is p. But we are not "given the value of p". What we are given is the observed data: the sun has risen every day on record. Laplace inferred the number of days by saying that the universe was created about 6000 years ago, based on a young-earth creationist reading of the Bible.
To find the conditional probability distribution of p given the data, one uses Bayes' theorem, which some call the Bayes–Laplace rule. Having found the conditional probability distribution of p given the data, one may then calculate the conditional probability, given the data, that the sun will rise tomorrow. That conditional probability is given by the rule of succession. The plausibility that the sun will rise tomorrow increases with the number of days on which the sun has risen so far. Specifically, assuming p has an a-priori distribution that is uniform over the interval [0,1], and that, given the value of p, the sun independently rises each day with probability p, the desired conditional probability is:
By this formula, if one has observed the sun rising 10000 times previously, the probability it rises the next day is . Expressed as a percentage, this is approximately a chance.
However, Laplace recognized this to be a misapplication of the rule of succession through not taking into account all the prior information available immediately after deriving the result:
E.T. Jaynes noted that Laplace's warning had gone unheeded by workers in the field.
A reference class problem arises: the plausibility inferred will depend on whether we take the past experience of one person, of humanity, or of the earth. A consequence is that each referent would hold different plausibility of the statement. In Bayesianism, any probability is a conditional probability given what one knows. That varies from one person to another.
See also
Rule of succession
Problem of induction
Doomsday argument: a similar problem that raises intense philosophical debate
Newcomb's paradox
Unsolved problems in statistics
Additive smoothing (also called Laplace smoothing)
References
Further reading
Howie, David. (2002). Interpreting probability: controversies and developments in the early twentieth century. Cambridge University Press. pp. 24.
Probability problems
Statistical inference
Bayesian statistics | Sunrise problem | Mathematics | 764 |
30,178,155 | https://en.wikipedia.org/wiki/The%207%20Habits%20of%20Highly%20Effective%20Teens | The Seven Habits of Highly Effective Teens is a 1998 bestselling self-help book written by Sean Covey, the son of Stephen Covey. The book was published on October 9, 1998 through Touchstone Books and is largely based on The Seven Habits of Highly Effective People. In 1999 Covey released a companion book entitled Daily Reflections For Highly Effective Teens.
In 2000, The 7 Habits of Highly Effective Teens was named as one of the YALSA's "Popular Paperbacks for Young Adults".
Synopsis
In the book Covey discusses how teenagers can become more independent and effective by following seven basic habits. The habits range from being proactive in every aspect of one's life to planning and prioritizing one's daily life and responsibilities.
Reception
Reception for the book has been positive, with some schools including the text in their lesson plans. A reviewer for the New Straits Times commented that the book's writing was "fun and lively" and called it a "fruitful read". AudioFile gave the audiobook a positive review, citing Covey's narration as a highlight. The 7 Habits of Highly Effective Teens has also been praised by several psychologists, although according to the Handbook of Self-Help Therapies the book has not been thoroughly tested as a part of a treatment plan.
References
External links
Official author website
Self-help books
Personal development
1998 non-fiction books
Touchstone Books books | The 7 Habits of Highly Effective Teens | Biology | 289 |
76,987,927 | https://en.wikipedia.org/wiki/Surface%20Pro%20%2811th%20generation%29 | </noinclude>
The Surface Pro (11th generation) (also referred to as the Surface Pro 11th Edition) is a 2-in-1 detachable tablet computer developed by Microsoft to supersede the Surface Pro 10 and Surface Pro X. It was released shortly after the Intel x86-based Surface Pro 10, and unveiled alongside the Surface Laptop (7th generation). The Surface Pro 11 introduces the Qualcomm Snapdragon X series CPUs to the Surface Pro model line, and therefore runs Windows on ARM. It is also the first Surface device with a built-in NPU designed for generative AI, via Microsoft Copilot+.
Background and reveal
Qualcomm announced the Snapdragon X line of CPUs on Oct 10, 2023. Microsoft announced the Surface Pro 11 and Surface Laptop (7th generation) at an AI-related press event on May 20, 2024. The press release touted performance, efficiency, and battery life that would rival the Macbook Air M3, and major performance gains over the Surface Pro 9. The CPU options available are the Snapdragon X Plus with 10 cores, and the Snapdragon X Elite with 12 cores. The devices contain a Hexagon NPU for use with Microsoft Copilot+ generative AI app.
Given the mixed reception of previous Surface on ARM devices, the Snapdragon X family of CPUs sought to provide the best performance, improved battery life, and lower heat output as compared to x86 Surface devices (the latter two still considered pain points of x86 Windows mobile devices). As well as integrate generative AI features and the Hexagon NPU. ARM-native apps have also seen larger support on Windows now than ever before. With the early Surface devices running Windows RT, complaints were lodged regarding the lack of compatible apps on Windows on ARM. The Surface Pro X showed improvements, with the introduction of an x86-compatibility layer to emulate x86 apps. The Surface Pro 11E introduces a new x86 emulator known as Prism, which promises better x86 emulation performance. Presently, Microsoft claims that 90% of total app minutes that users spend in apps now have native ARM versions. Google released Chrome on ARM in 2024 (with Google Drive announced Q3 2024), and Adobe has been rolling out ARM native apps for Photoshop, Illustrator, and Premiere Pro.
Hardware
The Surface Pro 11 is the 13th overall addition to the Surface Pro line.
Powered by Qualcomm Snapdragon X CPUs
Qualcomm Adreno integrated GPU (3.8 TFLOPS)
Qualcomm Hexagon NPU (45 TOPS)
Up to 1TB of SSD storage, Up to 32GB of memory
13-inch touchscreen 2880 x 1920 resolution display at 266 PPI, 3:2 aspect ratio,
and 120 Hz refresh rate, 600 nits brightness, IPS or OLED options available
Battery life rated at up to 14 hours video playback, 10 hours active web usage
IPS: 48Wh, OLED: 53Wh
2x USB-C ports with data transfer, charging, and DisplayPort 2.1
5G connectivity option available on business models
Surface Connect charging port
4K video camera support
39W power supply
Models
Microsoft Surface Pro 11 Copilot+ (IPS, Snapdragon X Plus)
• CPU: Snapdragon X Plus (X1P-64-100) • 10x Oryon @ 3.4 GHz
• GPU: Qualcomm SD X Adreno X1-85 (3.8 TFLOPS)
• Display: S-IPS 13" (3:2), 2880 x 1920 pixel (266 PPI), HDR, 120 Hz
Microsoft Surface Pro 11 Copilot+ (OLED, Snapdragon X Elite)
• CPU: Snapdragon X Elite (X1E-80-100) • 12x Oryon @ 4.0 GHz
• GPU: Qualcomm SD X Adreno X1-85 (3.8 TFLOPS)
• Display: OLED 13" (3:2), 2880 x 1920 pixel (266 PPI), HDR, 120 Hz
Software
Windows 11 includes Microsoft Copilot for AI features. Microsoft Recall, a controversial snapshot search history AI feature was disabled upon launch, and will be opt-in only once it launches. Recall was widely derided upon its reveal, citing security and privacy concerns, prompting Microsoft to make it an opt-in only feature.
Release and reception
The Surface Pro 11 was released on June 18, 2024, and received generally positive reviews. Praises include great performance for regular use, greatly improved battery life, impressive design and form factor, and much improved repairability. John Loeffler of Tech Radar admitted that the SP11 vastly surpassed his own expectations from the year prior, where he scoffed at the idea of another ARM-based Surface Pro being a good idea. Loeffler cites the improved x86 emulation via ‘’Prism’’, the outstanding battery life, OLED display, and performance. He cites it as a worthy competitor to the iPad Pro. Complaints were lodged at the expensive cost of the flex keyboard and Surface Pen (for a device that already has a baseline price of $999). He also feels that the AI features are still rather gimmicky, and that there still needs to be greater adoption of ARM-native apps for the platform.
Ed Bott of ZDNET says that the SP11 has replaced his daily driver tablet after one week of trying it out. He cited how much more cooled and quiet the device is, with his x86 Surface Pro would be uncomfortably hot for after the same amount of time doing the same tasks as he was. Per the battery life, he said that his initial impressions so far coupled with the battery report, indicate that the can get about twice as much battery life than his Surface Pro 9, and on-par with his Macbook Air M2. He was also very impressed with the camera. He said that app compatibility is a mixed bag. Some x86 apps run well, others are still problematic, and that ARM-native apps are gradually rolling out. He noted that at the time of review, Google Drive and popular VPN apps like Proton VPN and ExpressVPN are still only x86, and so users of those apps may want to stick with x86-based devices. He too expressed a mixed reception over the AI features, some felt gimmicky, others added a nice touch to existing apps.
Devindra Hardawar of Engadget cites the SP11 as the best Surface Pro device ever made, in spite of the AI, which he feels is a far less compelling reason to buy the device. While he feels it is overall solid, instead, the great performance of the Snapdragon X chips, great battery life, display, and flex keyboard are the true x-factors at play. He also notes that it can get expensive quickly, and that app compatibility still has its problems.
Tom Warren of The Verge commented on Windows on ARM as a whole. He noted that the Windows on ARM experience has improved dramatically from the Surface Pro X in 2019. Noting popular apps such as Photoshop, DropBox, Spotify, Prime, Hulu, Firefox, Chrome, Vivaldi, Edge, Brave, and Opera are all ARM-native now. He says that after a week, he has not seen the erratic behavior that plagued previous x86 emulation on Windows on ARM, but says it does not measure up quite to Microsoft's claimed performance. Ultimately, it depends on the complexity of the app. And that Qualcomm should engage with app developers on how to best optimize the apps for the hardware, as they cannot rely on Prism to handle everything. He also states that gaming experience is lacking: Some games will not even run, others run at a particularly mid performance, and many anti-cheat software use kernel drivers that are not yet supported by emulation. He ultimately feels that ARM-native app accessibility will only improve within the coming years, and that Windows on ARM finally feels poised to succeed.
Serviceability and repairability
Microsoft has released service guides for Surface Pro 11 and Surface Laptop 7.
iFixit has given both the Surface Pro 11 Surface Laptop 7 an overall rating of 8/10 on the repairability scale. Noting the improvements over previous Surface devices, and the user-removable SSD.
Timeline
Notes
References
Tablet computers introduced in 2024
Microsoft Surface
2-in-1 PCs | Surface Pro (11th generation) | Technology | 1,771 |
76,673,219 | https://en.wikipedia.org/wiki/IC%2064 | IC 64 is a massive lenticular galaxy located 622 million light-years away in the Pisces constellation. IC 64 has a diameter of 300,000 light-years, making it, three times bigger than the Milky Way and one of the largest galaxies observed. IC 64 was discovered by French astronomer Stephane Javelle on 5 December 1893. It has an active galactic nucleus, and is an emission line galaxy.
References
Lenticular galaxies
0064
Pisces (constellation)
00613
003550
+04-03-031
003550
Astronomical objects discovered in 1893
Active galaxies | IC 64 | Astronomy | 121 |
24,320,320 | https://en.wikipedia.org/wiki/C6H11NO3 | {{DISPLAYTITLE: C6H11NO3}}
The molecular formula C6H11NO3 (molar mass: 145.16 g/mol, exact mass: 145.0739 u) may refer to:
N-Acetyl-γ-aminobutyric acid
Allysine
Methyl aminolevulinate (MAL)
Molecular formulas | C6H11NO3 | Physics,Chemistry | 77 |
19,081,302 | https://en.wikipedia.org/wiki/The%20Machine%20That%20Changed%20the%20World%20%28TV%20series%29 | The Machine That Changed the World (1992) (broadcast the previous year under the alternative title "The Dream Machine" in the UK, with different narration, content & editing) is a 5-episode television series on the history of electronic digital computers. It was written and directed by Nancy Linde, and produced by WGBH Television of Boston, Massachusetts, and the British Broadcasting Corporation. Backers included the Association for Computing Machinery, the National Science Foundation, and the UNISYS Corporation.
The first three episodes deal with the history of fully electronic general-purpose digital computers from the ENIAC through desktop microcomputers. The pre-history of such machines is examined in the first episode ("Giant Brains"), and includes a discussion of the contributions of Charles Babbage, Ada Lovelace, Alan Turing, and others. The fourth episode ("The Thinking Machine") explores the topic of artificial intelligence. The fifth episode ("The World at Your Fingertips") explores the then-newly-emerging worldwide networking of computers. All episodes begin and end with a song by Peter Howell, "Stellae matutinae radius exoritur" ("The morning star's ray arises") and are narrated by long-time Frontline narrator Will Lyman.
External links
Video resource guide at American University Computing History Museum
Episode synopses at Virginia Tech
Synopsis of Episode 1, "Giant Brains" at waxy.org
Synopsis of Episode 2, "Inventing the Future", at waxy.org
Synopsis of Episode 3, "The Paperback Computer", at waxy.org
Synopsis of Episode 4, "The Thinking Machine", at waxy.org
Synopsis of Episode 5, "The World at Your Fingertips", at waxy.org
1990s American documentary television series
Documentary television series about computing | The Machine That Changed the World (TV series) | Technology | 373 |
73,307,706 | https://en.wikipedia.org/wiki/Sodium%20p-toluenesulfonate | Sodium p-toluenesulfonate is an organic compound with the formula . It is white, water-soluble solid. It is produced by the neutralization toluenesulfonic acid with sodium hydroxide. It is also a common product from the reactions of sodium-based reagents with toluenesulfonates.
Heating this salt in strong base results in desulfonation, giving, after acid workup, p-cresol.
References
Sulfonyl groups
Leaving groups
Sulfonates | Sodium p-toluenesulfonate | Chemistry | 107 |
57,617,861 | https://en.wikipedia.org/wiki/Hans%20P.%20Eugster | Hans Peter Eugster (November 19, 1925, in Igis, Switzerland – December 17, 1987, in Baltimore, US) was a Swiss-American geochemist, mineralogist, and petrologist.
Education
Eugster studied at ETH Zurich with Diplom in 1948 and D.Sc. in 1951 under Paul Niggli with a dissertation on metamorphic recrystallization in the eastern part of the Aar massif. As a postdoctoral fellow, Eugster studied optical spectroscopy from 1951 to 1952 at the Massachusetts Institute of Technology, where he was also influenced by research on petrology done by James Burleigh Thompson's team at Harvard University.
Career
Eugster then went to the Geophysical Laboratory of the Carnegie Institution in Washington, DC. There, from 1952 to 1958, he studied experimental mineralogy under Hatten Yoder, specializing in high temperatures and aqueous fluid pressures.
He investigated the Green River Formation, later followed by worldwide investigations of other salt deposits. He became in 1958 Associate Professor of Experimental Petrology at Johns Hopkins University and in 1960 Professor. From 1983 to 1987 he was the director of the faculty of geosciences. He was also an adjunct professor at the University of Wyoming from 1970 onwards. He died unexpectedly from an aortic rupture.
Awards and honors
He was elected in 1972 a member of the United States National Academy of Sciences and, in the same year, a fellow of the American Academy of Arts and Sciences. He received in 1983 the Roebling Medal, in 1976 the V. M. Goldschmidt Award, and in 1971 the Arthur L. Day Medal. In 1985 he was president of the Mineralogical Society of America.
The salt mineral eugsterite from Lake Victoria in Kenya was named after him in 1981.
Personal life
His brother was a chemist and professor at the University of Zurich. He was married to Elaine Koppelman.
Selected works
Heterogeneous reactions involving oxidation and reduction at high pressures and temperatures, J. Chem. Phys., Vol. 26, 1957, pp. 1760–1761
with Charles Milton: Mineral assemblages in the Green River Formation, in P.H. Abelson, Researches in Geochemistry, Wiley 1959, pp. 18–150
Reduction and Oxidation in Metamorphism, in P.H. Abelson, Researches in Geochemistry, Wiley 1959, pp. 397–426
with B.M. French. Experimental control of oxygen fugacities by graphite-gas equilibriums, J. Geophys. Res., Vol. 70, 1965, pp. 1529–1539.
with D.R. Wones: Stability of Biotite: Experiment, Theory, and Application., American Mineralogist, Vol. 50, 1965, pp. 1228–1272.
with J. L. Munoz: Experimental control of fluorine reactions in hydrothermal systems. American Mineralogist, Vol. 54, 1969, pp. 943–959.
with L.A. Hardie: The Evolution of Closed Basin Brines, Mineralogical Society of America Special Publ., 3, 1970, pp. 273–290
The Beginnings of Experimental Petrology, Science, Vol. 173, 1971, pp. 481–489
with C.E. Harvie, J.H. Weare, L. A. Hardie. Evaporation of sea water: Calculated mineral sequences, Science, Vol. 208, 1980, pp. 498–500.
Oil shales, evaporites and ore deposits. Geochim. et Cosmochim. Acta, Vol. 49, 1985, pp. 619–635.
with R.J. Spencer, B.F. Jones, S.L. Rettig: Geochemistry of Great Salt Lake, Utah, Part 1, 2, Geochim. et Cosmochim. Acta, Vol. 49, 1985, pp. 727–737, 739–774
References
External links
American mineralogists
American geochemists
Swiss mineralogists
Petrologists
Johns Hopkins University faculty
Fellows of the American Academy of Arts and Sciences
Members of the United States National Academy of Sciences
1925 births
1987 deaths
Recipients of the V. M. Goldschmidt Award
20th-century American chemists
ETH Zurich alumni | Hans P. Eugster | Chemistry | 893 |
45,402,722 | https://en.wikipedia.org/wiki/The%20AWK%20Programming%20Language | The AWK Programming Language is a well-known 1988 book written by Alfred V. Aho, Brian W. Kernighan, and Peter J. Weinberger and published by Addison-Wesley, often referred to as the gray book. The book describes the AWK programming language and is the de facto standard for the language, written by its inventors. W. Richard Stevens, author of several UNIX books including Advanced Programming in the Unix Environment, cites the book as one of his favorite technical books. The book is translated to several languages and is cited by many technical papers in the ACM journals.
According to the book's frontmatter the book was typeset "using an Autologic APS-5 phototypesetter and a DEC VAX 8550 running the 9th Edition of the UNIX operating system".
In September 2023, the second edition was published by Addison-Wesley, along with an accompanying website.
Books
References
External links
The Awk Programming Language book review - IEEE
Computer books
Computer_programming_books
Addison-Wesley books | The AWK Programming Language | Technology | 213 |
8,555,460 | https://en.wikipedia.org/wiki/Boeing%20EC-135 | The Boeing EC-135 is a retired family of command and control aircraft derived from the Boeing C-135 Stratolifter. During the Cold War, the EC-135 was best known for being modified to perform the Looking Glass mission where one EC-135 was always airborne 24 hours a day to serve as flying command post for the Strategic Air Command in the event of nuclear war. Various other EC-135 aircraft sat on airborne and ground alert throughout the Cold War, with the last EC-135C being retired in 1998. The EC-135N variant served as the tracking aircraft for the Apollo program.
The Boeing E-6B Mercury "TACAMO" replaced the EC-135C.
Missions
Looking Glass
Officially known as "Operation Looking Glass", at least 11 EC-135C command post aircraft were provided to the Commander in Chief, Strategic Air Command (CINCSAC), and were based at various locations throughout the United States and worldwide. Operations began in 1961 with the 34th Air Refueling Squadron at Offutt Air Force Base (Nebraska), initially using EC-135As (converted from KC-135As) until the dedicated EC-135Cs entered service in 1964. Originally built as KC-135Bs, they were re-designated as EC-135Cs from 1 January 1965. Other Offutt-based units included the 38th Strategic Reconnaissance Squadron (1966–1970), the 2d Airborne Command and Control Squadron (1970–1994), and the 7th Airborne Command and Control Squadron (1994–1998). Other units operating the Looking Glass mission included the following:
913th Air Refueling Squadron at Barksdale Air Force Base (Louisiana) (1963–1970)
3rd Airborne Command & Control Squadron at Grissom Air Force Base (Indiana) (1970–1974)
4th Airborne Command & Control Squadron at Ellsworth Air Force Base, (South Dakota) (1970–1991)
99th Air Refueling Squadron, Westover Air Force Base (Massachusetts) (1963–1970)
Other EC-135 aircraft (including EC-135A, G, and L models) supporting the Looking Glass missions (communications relay and Minuteman airborne launch control centers) were flown by the 906th Air Refueling Squadron at Minot Air Force Base (North Dakota) (1963–1970), the 70th Air Refueling Squadron at Grissom AFB (1975–1993), and the 301st Air Refueling Squadron at Lockbourne Air Force Base (Ohio) (1963–1970). All aircraft have been retired or repurposed.
The United States nuclear strategy depends on its ability to command, control, and communicate with its nuclear forces under all conditions. An essential element of that ability is Looking Glass; its crew and staff ensure there is always an aircraft ready to direct bombers and missiles from the air should ground-based command centers be destroyed or rendered inoperable. Looking Glass is intended to guarantee that U.S. strategic forces will act only in the manner dictated by the President. It took the nickname "Looking Glass" because the mission mirrored ground-based command, control, and communications centers.
The Strategic Air Command (SAC) began the Looking Glass mission on February 3, 1961, and Looking Glass aircraft were continuously airborne 24 hours a day for over 29 years, accumulating more than 281,000 accident-free flying hours. On July 24, 1990, "The Glass" ceased continuous airborne alert, but remained on ground or airborne alert 24 hours a day. The EC-135A flew the Command Post mission until EC-135C were delivered starting in 1963. The aircraft were delivered to Offutt AFB and as well as one aircraft to each of the Stateside Numbered Air Force Headquarters – Second Air Force at Barksdale AFB (Louisiana); Eighth Air Force at Westover AFB (Massachusetts); and Fifteenth Air Force at March AFB (California). EC-135s flew all the missions except one, on March 4, 1980, when an E-4B was tested on an operational mission, flying a double sortie as the replacement aircraft could not launch due to weather. About a week after the flight, Washington deleted the funds for additional E-4 aircraft.
On June 1, 1992, SAC was inactivated and replaced by the United States Strategic Command, which now controls the Looking Glass. On October 1, 1998, the Navy's E-6 Mercury TACAMO replaced the USAF's EC-135C in the Looking Glass mission. The last active, former, Looking Glass was converted to a WC-135C Constant Phoenix, where it was retired in November 2020.
Notes
Ellsworth AFB maintained additional EC-135 aircraft on Satellite Alert at Minot AFB to monitor the North Dakota missile silos.
Airborne Launch Control Center
Airborne Launch Control Centers (ALCC—pronounced "Al-see") provided a survivable launch capability for the United States Air Force's LGM-30 Minuteman Intercontinental Ballistic Missile (ICBM) force by utilizing the Airborne Launch Control System (ALCS) on board that is operated by an airborne missileer crew. Historically, from 1967 to 1998, the ALCC mission was performed by United States Air Force Boeing EC-135 command post aircraft. This included EC-135A, EC-135C, EC-135G, and EC-135L aircraft.
In the late 1960s and early 1970s, ALCS crews belonged to the 44th Strategic Missile Wing (SMW) at Ellsworth AFB and the 91st SMW at Minot AFB. ALCS equipment was installed on various Boeing EC-135 variants to include the EC-135A, EC-135C, EC-135G, and for a short while on the EC-135L.
Starting in 1970, there were only two SAC squadrons that operated ALCS capable aircraft. This included the 2nd Airborne Command and Control Squadron (ACCS) operating EC-135C aircraft out of Offutt AFB and the 4th ACCS operating EC-135A, EC-135C, and EC-135G aircraft out of Ellsworth AFB . All three variants of these EC-135A/C/G aircraft had ALCS equipment installed on board.
The 4th ACCS was the workhorse of ALCS operations. Three dedicated Airborne Launch Control Centers (ALCC) were on ground alert around-the-clock providing ALCS coverage for five of the six Minuteman ICBM Wings. These dedicated ALCCs were mostly EC-135A aircraft but could also have been EC-135C or EC-135G aircraft depending on availability. ALCC No. 1 was on ground alert at Ellsworth AFB and during a wartime scenario would have taken off and orbited between the Minuteman Wings at Ellsworth AFB and F.E. Warren AFB (Wyoming) providing ALCS assistance if needed. ALCCs No. 2 and No. 3 were routinely on forward deployed ground alert at Minot AFB. During a wartime scenario, ALCC No. 3 would have orbited between the Minuteman ICBM Wings at Minot AFB and Grand Forks AFB, both in North Dakota, providing ALCS assistance if needed. ALCC No. 2 was dedicated to orbiting near the Minuteman ICBM Wing at Malmstrom AFB (Montana) providing ALCS assistance if needed. The 4th ACCS also maintained an EC-135C or EC-135G on ground alert at Ellsworth AFB as the West Auxiliary Airborne Command Post (WESTAUXCP) as a backup to SAC's "Looking Glass" Airborne Command Post (ABNCP) as well as a radio relay link between the Looking Glass and ALCCs when airborne. Although equipped with ALCS, the WESTAUXCP did not have a dedicated Minuteman ICBM wing to provide ALCS assistance to.
The 2nd ACCS was another major player in ALCS operations. The primary mission of the 2nd ACCS was to fly the SAC ABNCP "Looking Glass" aircraft in continuous airborne operations. However, due to its proximity in orbiting over the central United States, the airborne Looking Glass provided ALCS coverage for the Minuteman ICBM Wing located at Whiteman AFB (Missouri). Not only did Whiteman AFB have Minuteman II ICBMs, but it also had ERCS configured Minuteman missiles on alert. The 2nd ACCS also had an additional EC-135C on ground alert at Offutt AFB as the EASTAUXCP, providing backup to the airborne Looking Glass, radio relay capability, and a means for the Commander in Chief of SAC to escape an enemy nuclear attack. Although the EASTAUXCP was ALCS capable, it did not have a dedicated ALCS mission.
Silk Purse
Operation Silk Purse program provided four EC-135H command post aircraft to the Commander, U.S. European Command (USEUCOM), which were based at RAF Mildenhall in the United Kingdom. Flown by the 10th Airborne Command and Control Squadron 1970–91. Onboard secure/non-secure communications and avionics equipment was maintained by the 513th Avionics Maintenance Squadron and the 2147th Communications Squadron. Aircraft S/Ns 61–0282, 285, 286 and 291.
Scope Light
Operation Scope Light provided five EC-135C/HJ/P command post aircraft to the Commander in Chief, U.S. Atlantic Command (CINCLANT), which were based at Langley AFB (Virginia). Operated by the 6th Airborne Command and Control Squadron 1972–92.
Blue Eagle
Operation Blue Eagle provided five EC-135J/P command post aircraft to the Commander in Chief, U.S. Pacific Command (USCINCPAC), which were based at Hickam AFB (Hawaii). Operated by the 9th Airborne Command and Control Squadron 1969–92. Communications, secure/unsecure voice and teletype, handled by the 1957th Communications Group, Hickam AFB (1969–1992)
"Upkeep" was the call sign for the EC135 flying in southeast Asia during 1969 to 1971, based out of Hickam AFB. It was under the direction of PACAF of which 5th AF in Fuchu AS, Tokyo
Japan handled their voice communications both unsecure and secure.
<1956 Comm Gp USAF 1969 to 1971>
Blue Eagle Ground Stations were located at Hickam AFB, Yakoto AB (Japan) Kadena AB (Okinawa), and Clark AB (Philippines). There may have been an additional Ground Station on Guam.
At Kadena AB, the 1962nd Communications Group hosted the Blue Eagle Ground Station. The call sign for the Kadena Blue Eagle Operation was “Settler”.
All Blue Eagle Ground Stations were contracted to Philco Corporation and consisted of two trailer vans that could be pulled by a single tractor. One van was configured with a 15KW diesel powered generator and diesel fuel tank and the other was outfitted with a 15-ton heavy duty air conditioning unit, three motor generators, three UHF/VHF FM transmitters and receivers, two multiplexers each providing up to 24 telephone lines and a dedicated, individual telephone line provided to the aircraft.
The ground stations were self sufficient in that they were configured in trailers so they could be relocated to safer positions in the event of a national emergency. The equipment installed in the vans was identical to the electronics on board the aircraft. This necessitated the requirement for motor-generators to provide conversion from 60 Hz to 400 Hz power.
Each equipment van had an omni-directional antenna mounted on the roof of the van and 3 additional portable antennas that were deployed on telephone poles. The antennas could be switched electro-mechanically from each transmitter/receiver pair. The vans at Kadena AB were never moved from their initial installation location.
Blue Eagle was formed in 1965 and started 24/7 operation in October 1965 and continued until disbanded in 1992.
Nightwatch
Operation Nightwatch provided three EC-135J command post aircraft to the President of the United States which were based at Andrews AFB (Maryland). All three aircraft were transferred to other ABNCP missions.
Nightwatch was initiated in the mid-1960s utilizing the three EC-135J aircraft, modified from KC-135Bs, as command post aircraft. The three Nightwatch aircraft were ready to fly the President and the National Command Authority (NCA) out of Washington in the event of a nuclear attack. The E-4 aircraft (a modified Boeing 747-200) came on line with the Nightwatch program in 1974 replacing the EC-135s on this mission.
USCENTCOM Support
The 310th Airlift Squadron, part of the 6th Air Mobility Wing at MacDill AFB (Florida), operated two NKC-135s that were reconfigured as EC-135Y aircraft from 1989 to 2003 as executive transport and command & control platforms to support the Commander, United States Central Command. These aircraft have since been replaced with three C-37A Gulfstream V aircraft.
Advanced Range Instrumentation Aircraft
The Advanced Range Instrumentation Aircraft are EC-135Bs, modified C-135B cargo aircraft and EC-18B (former American Airlines 707-320) passenger aircraft that provided tracking and telemetry information to support the US space program in the late 1960s and early 1970s.
During the early 1960s, NASA and the Department of Defense (DoD) needed a very mobile tracking and telemetry platform to support the Apollo space program and other unmanned space flight operations. In a joint project, NASA and the DoD contracted with the McDonnell Douglas and the Bendix Corporations to modify eight Boeing C-135 Stratolifter cargo aircraft into EC-135N Apollo / Range Instrumentation Aircraft (A/RIA). Equipped with a steerable seven-foot antenna dish in its distinctive "Droop Snoot" or "Snoopy Nose", the EC-135N A/RIA became operational in January 1968, and was often known as the "Jimmy Durante" of the Air Force. The Air Force Eastern Test Range (AFETR) at Patrick AFB, Florida, maintained and operated the A/RIA until the end of the Apollo program in 1972, when the USAF renamed it the Advanced Range Instrumentation Aircraft (ARIA).
Since Patrick AFB was located on the Atlantic Ocean, salt water and salt air-induced corrosion issues and associated aircraft maintenance challenges were problematic for the ARIA while based there. Transferred to the 4950th Test Wing at Wright-Patterson AFB, Ohio, in December 1975 as part of an overall consolidation of large test and evaluation aircraft, the ARIA fleet underwent numerous conversions, including a re-engining that changed the EC-135N to the EC-135E. In 1994, the ARIA fleet relocated again to Edwards AFB, California, as part of the 412th Test Wing. However, taskings for the ARIA dwindled because of high costs and improved satellite technology, and the USAF transferred the aircraft to other programs such as E-8 J-STARS.
Over its thirty-two year career, the ARIA supported the United States space program, gathered telemetry, verified international treaties, and supported cruise missile, ballistic missile defense tests, and the Space Shuttle. ARIA aircraft were equipped to collect data from the Sonobuoy Missile Impact Location System (SMILS) composed of a large sonobuoy field and a fixed bottom transponder. Specially equipped Navy P-3 aircraft were also equipped to collect data from this system which supported the Navy's fleet ballistic missile programs testing.
Variant summary
EC-135A – KC-135A modified for airborne national command post role. Later performed Airborne Launch Control Center mission with the Airborne Launch Control System.
EC-135B – C-135B modified with large nose for ARIA mission
EC-135C – re-designated KC-135B to EC-135C for airborne command post role, "Looking Glass"
EC-135E – re-engined EC-135N, "Advanced Range Instrumentation Aircraft" or "ARIA"
EC-135G – KC-135A modified for airborne national command post role. Later performed Airborne Launch Control Center mission with the Airborne Launch Control System.
EC-135H – KC-135A modified for airborne national command post role, "Silk Purse"
EC-135J – KC-135B modified for airborne national command post role, "Nightwatch"
EC-135K – KC-135A modified for deployment control duties, "Head Dancer"
EC-135L – KC-135A modified for radio relay and amplitude modulation dropout capability "Cover All"
EC-135N – ARIA aircraft with the so-called "droop snoot" radome housing a large parabolic telemetry gathering antenna.
EC-135J/P – KC-135A modified for airborne command post role, "Blue Eagle" and "Scope Light"
EC-135Y – NKC-135 reconfigured as C3 aircraft for Commander-in-Chief, United States Central Command
Accidents
On 13 June 1971, USAF EC-135N, (AF Serial Number 61-0331), of 4950th Test Wing, Space and Missile Systems Organization (SAMSO), Wright-Patterson AFB disappeared while en route from Pago Pago, American Samoa to Hickam AFB in Hawaii after monitoring a French atmospheric test conducted on the previous day. The aircraft disappeared about 70 miles south of Hawaii near Palmyra Island. Twelve military personnel and twelve civilians died. Cause of the mishap is unknown. Only small bits of wreckage were found.
On 14 September 1977, USAF EC-135K, (AF Serial Number 62-3536), crashed on takeoff from Kirtland Air Force Base, NM for a Higher-Headquarters Directed (HHD) mission. After a long crew duty period, the crew started its takeoff roll at a few minutes prior to midnight. The aircraft impacted the ground 8 km (5 miles) east of the departure base because it lacked sufficient power to either climb above or turn to avoid rapidly rising terrain in that area. All 20 occupants of this Tactical Air Command (TAC) operated aircraft were killed in the crash and subsequent fire at about 8,500 feet up the Manzano Mountain Range east of Albuquerque, NM.
On 2 January 1980, USAF EC-135P, (AF Serial Number 58-0007), was destroyed on the ground at Langley AFB when an electrical short occurred in the water injection tank heater wiring on the J-57-P/F-59W equipped aircraft. There were no injuries as the Tactical Air Command (TAC) aircraft was unoccupied at the time of the mishap.
On 6 May 1981, USAF EC-135N, (AF Serial Number 61-0328), crashed during a scheduled Advanced Range Instrumented Aircraft (ARIA) navigator and Primary Mission Electronic Equipment (PMEE) training mission from Wright-Patterson Air Force Base, OH. For an unexplained reason, the aircraft pitch trim was moved to the full nose-down position, which exceeded the ability of the autopilot to control, and the aircraft pitched over abruptly. The abrupt pitch over caused the generators to trip off line and the loss of AC electrical power prevented the pitch trim from being operated normally. The aircraft became uncontrollable and exploded at about 1,500 ft MSL. The crash occurred near Walkersville, MD at 10:50L. All seventeen crew members and four passengers on board the aircraft were killed.
On 29 May 1992, USAF EC-135J, (AF Serial Number 62-3584), landed long at Pope AFB (North Carolina) and overshot the runway. The undercarriage collapsed and the fuselage broke in two. Although none of the 14 occupants were seriously injured, the aircraft was written off as damaged beyond repair and the remains were removed to Davis-Monthan AFB (Arizona) for disposal.
On 2 September 1997, USAF EC-135C, (AF Serial Number 63-8053), was heavily damaged on landing at Pope AFB when the nose wheel collapsed. None of the 11 occupants was injured significantly, but the Air Combat Command (ACC) aircraft was 32 years and 10 months old at the time of the accident and was written off as damaged beyond repair.
Aircraft on display
60-0374 The Bird of Prey – EC-135E (originally built as a C-135A, later converted to EC-135N) on static display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio. The aircraft is a former Advanced Range Instrumented Aircraft (ARIA) designated as an EC-135N model with J57-59 engines, and is displayed in the museum's outside Air Park; nose art remains. The aircraft was flown to the museum on November 3, 2000, by a flight crew from the Air Force Flight Test Center (AFFTC), and was delivered with full Prime Mission Electronic Equipment intact.
61-0262 Rollin' Thunder – EC-135A (originally built as a KC-135A) on static display at the South Dakota Air and Space Museum in Box Elder, South Dakota; nose art remains. It was last assigned to the 4th Airborne Command and Control Squadron (4th ACCS), 28th Bomb Wing at Ellsworth.
61-0269 Excaliber – EC-135L (originally built as a KC-135A) on static display at the Grissom Air Museum near Peru, Indiana. The aircraft was last assigned to the 305th Air Refueling Wing and retired in 1992, at the end of the Cold War. It was delivered to the Air Force on 8 December 1961. Assigned to Grissom AFB in 1970, the aircraft flew many missions during Operation Just Cause, Operation Desert Shield and Desert Storm. For the latter, it performed radio relay operations leading to the elimination of two Iraqi aircraft, over 60 tank kills, and 27 Scud missile strikes.
61-0287 – EC-135A Airborne Launch Control Center/radio relay link aircraft (originally built as a KC-135A) on static display at Zorinsky Memorial Air Park at Offutt Air Force Base in Bellevue, Nebraska.
61-0327 – on static display at the Museum of Aviation, Robins AFB
63-8049 – EC-135C (originally built as a KC-135B), on display at the Strategic Air Command & Aerospace Museum in Ashland, Nebraska.
63-8057 – EC-135J (originally built as a KC-135B) on static display at the Pima Air and Space Museum in Tucson, Arizona.
See also
Airborne Launch Control System
Airborne Launch Control Center
Post Attack Command and Control System
Operation Looking Glass
Emergency Rocket Communications System
References
Reference for the Variant Summary list: DoD 4120.14L, Model Designation of Military Aerospace Vehicles, May 12, 2004
External links
USSTRATCOM ABNCP Fact Sheet
EC-0135, Boeing
Military communications
United States nuclear command and control
Telemetry
C-135E, Boeing
1960s United States military reconnaissance aircraft
Quadjets
Historic American Engineering Record in Nebraska
Low-wing aircraft
Aircraft first flown in 1965
Aircraft with retractable tricycle landing gear | Boeing EC-135 | Engineering | 4,708 |
24,320,326 | https://en.wikipedia.org/wiki/C20H23NO4 | {{DISPLAYTITLE:C20H23NO4}}
The molecular formula C20H23NO4 may refer to:
Efaproxiral, an allosteric effector of hemoglobin
Isopavine, an alkaloid
6-Monoacetylcodeine, a codein ester
Naltrexone, a medication primarily used to manage alcohol dependence
Osemozotan, an experimental drug candidate
Pavine, an alkaloid found in poppy species
Thebacon, a semisynthetic opioid used as an analgesic | C20H23NO4 | Chemistry | 121 |
1,428,177 | https://en.wikipedia.org/wiki/Deicing | De-icing is the process of removing snow, ice or frost from a surface. Anti-icing is the application of chemicals that not only de-ice but also remain on a surface and continue to delay the reformation of ice for a certain period of time, or prevent adhesion of ice to make mechanical removal easier.
De-icing can be accomplished by mechanical methods (scraping, pushing); through the application of heat; by use of dry or liquid chemicals designed to lower the freezing point of water (various salts or brines, alcohols, glycols); or by a combination of these different techniques.
Application areas
Roadways
In 2013, an estimated 14 million tons of salt were used for de-icing roads in North America.
De-icing of roads has traditionally been done with salt, spread by snowplows or dump trucks designed to spread it, often mixed with sand and gravel, on slick roads. Sodium chloride (rock salt) is normally used, as it is inexpensive and readily available in large quantities. However, since salt water still freezes at , it is of no help when the temperature falls below this point. It also has a tendency to cause corrosion, rusting the steel used in most vehicles and the rebar in concrete bridges. Depending on the concentration, it can be toxic to some plants and animals, and some urban areas have moved away from it as a result. More recent snowmelters use other salts, such as calcium chloride and magnesium chloride, which not only depress the freezing point of water to a much lower temperature, but also produce an exothermic reaction. They are somewhat safer for sidewalks, but excess should still be removed.
More recently, organic compounds have been developed that reduce the environmental issues connected with salts and have longer residual effects when spread on roadways, usually in conjunction with salt brines or solids. These compounds are often generated as byproducts of agricultural operations such as sugar beet refining or the distillation process that produces ethanol. Other organic compounds are wood ash and a de-icing salt called calcium magnesium acetate made from roadside grass or even kitchen waste. Additionally, mixing common rock salt with some of the organic compounds and magnesium chloride results in spreadable materials that are both effective to much colder temperatures () as well as at lower overall rates of spreading per unit area.
Solar road systems have been used to maintain the surface of roads above the freezing point of water. An array of pipes embedded in the road surface is used to collect solar energy in summer, transfer the heat to thermal banks and return the heat to the road in winter to maintain the surface above . This automated form of renewable energy collection, storage and delivery avoids the environmental issues of using chemical contaminants.
It was suggested in 2012 that superhydrophobic surfaces capable of repelling water can also be used to prevent ice accumulation leading to icephobicity. However, not every superhydrophobic surface is icephobic and the method is still under development.
Trains and rail switches
Trains and rail switches in Arctic regions can have significant problems with snow and ice build up. They need a constant heat source on cold days to ensure functionality. On trains it is primarily the brakes, suspension, and couplers that require heaters for de-icing. On the rails it is primarily track switches that are sensitive to ice. High-powered electrical heaters prevent ice formation and rapidly melt any ice that forms.
The heaters are preferably made of PTC material, for example PTC rubber, to avoid overheating and potentially destroying the heaters. These heaters are self-limiting and require no regulating electronics; they cannot overheat and require no overheat protection.
Aviation
Ground de-icing of aircraft
On the ground, when there are freezing conditions and precipitation, de-icing an aircraft is commonly practiced. Frozen contaminants interfere with the aerodynamic properties of the vehicle. Furthermore, dislodged ice can damage the engines.
Ground de-icing methods include:
Spraying on various aircraft deicing fluids to melt ice and prevent reformation
Using unheated forced air to blow off loose snow and ice
Using infrared heating to melt snow, ice, and frost without using chemicals
Mechanical deicing using tools such as brooms, scrapers, and ropes
Placing an aircraft in a warm hangar
In-flight de-icing
Ice can build up on aircraft in flight due to atmospheric conditions, causing potential degradation of flight performance. Large commercial aircraft almost always have in-flight ice protections systems to shed ice buildup and prevent reformation. Ice protection systems are
becoming increasingly common in smaller general aviation aircraft as well.
Ice protection systems typically use one or more of the following approaches:
pneumatic rubber "boots" on leading edges of wings and control surfaces, which expand to break off accumulated ice
electrically heated strips on critical surfaces to prevent ice formation and melt accumulated ice
bleed air systems which take heated air from the engines and duct them to locations where ice can accumulate
fluid systems which "weep" de-icing fluid over wings and control surfaces via tiny holes
Airport pavement
De-icing operations for airport pavement (runways, taxiways, aprons, taxiway bridges) may involve several types of liquid and solid chemical products, including propylene glycol, ethylene glycol and other organic compounds. Chloride-based compounds (e.g. salt) are not used at airports, due to their corrosive effect on aircraft and other equipment.
Urea mixtures have also been used for pavement de-icing, due to their low cost. However, urea is a significant pollutant in waterways and wildlife, as it degrades to ammonia after application, and it has largely been phased out at U.S. airports. In 2012 the U.S. Environmental Protection Agency (EPA) prohibited use of urea-based de-icers at most commercial airports.
Water agitator de-icer
Water agitators are electric motors put under water that propel up warmer water and agitate the surface with it to de-ice aquatic structures on rivers and lakes in freezing temperatures. There are also agitator bubblers that use compressed air, run through a hose, and released to agitate the water.
De-icing chemicals
All chemical de-icers share a common working mechanism: they chemically prevent water molecules from binding above a certain temperature that depends on the concentration. This temperature is below 0 °C, the freezing point of pure water (freezing point depression). Sometimes, there is an exothermic dissolution reaction that allows for an even stronger melting power. The following lists contains the most-commonly used de-icing chemicals and their typical chemical formula.
Salts
Sodium chloride (NaCl or table salt; the most common de-icing chemical)
Magnesium chloride (, often added to salt to lower its working temperature)
Calcium chloride (, often added to salt to lower its working temperature, attacks concrete)
Potassium chloride (KCl)
Calcium magnesium acetate ()
Potassium acetate ()
Potassium formate ()
Sodium formate (HCOONa)
Calcium formate ()
Organics
Urea (), a common fertilizer
Agricultural by-products, generally used as additives to sodium chloride
Methanol (), scarcely used on roads
Ethylene glycol (), scarcely used on roads
Propylene glycol (), scarcely used on roads
Glycerol (), scarcely used on roads
Environmental impact and mitigation
De-icing salts such as sodium chloride or calcium chloride leach into natural waters, strongly affecting their salinity.
Ethylene glycol and propylene glycol are known to exert high levels of biochemical oxygen demand (BOD) during degradation in surface waters. This process can adversely affect aquatic life by consuming oxygen needed by aquatic organisms for survival. Large quantities of dissolved oxygen (DO) in the water column are consumed when microbial populations decompose propylene glycol.
Some airports recycle used de-icing fluid, separating water and solid contaminants, enabling reuse of the fluid in other applications. Other airports have an on-site wastewater treatment facility, and/or send collected fluid to a municipal sewage treatment plant or a commercial wastewater treatment facility.
See also
Atmospheric icing
Pollution
Winter service vehicle
References
External links
Aviation safety
Aviation risks
Transport safety
Chemical processes
Ice in transportation
NASA spin-off technologies | Deicing | Physics,Chemistry | 1,732 |
70,750,727 | https://en.wikipedia.org/wiki/Schizothecium%20miniglutinans | Schizothecium miniglutinans is a species of coprophilous fungus in the family Lasiosphaeriaceae. It is known to grow in the dung of goats and possibly on that of sheep.
References
External links
Fungi described in 1972
Fungi of Greece
Sordariales
Fungus species | Schizothecium miniglutinans | Biology | 64 |
64,543,211 | https://en.wikipedia.org/wiki/Hentak | Hentak is a thick fermented paste in Manipuri cuisine made with sun-dried fish powder and the petioles of aroid plants. The small Indian flying barb fish are sun dried on bamboo trays and crushed to powder. The aroid petioles are cut into pieces and left in the sun for one day, then in equal parts with the fish powder the mixture is sealed in an earthen pot and fermented for around one week.
Hentak is a standard ingredient in Manipuri households, where it is consumed as a condiment with boiled rice or curry. Some preparations may include other plant ingredients like Colocasia esculenta. The standard ingredient of aroid petioles enhances flavor and also serves the purpose of aiding the fermentation process. In Manipur, hentak is a homemade preparation that is not produced for commercial markets. It is custom to serve this to expecting mothers and patients in convalescent.
Another fish paste from Northeast India is tungtap.
See also
Fermented fish
Garum
Bagoong
Terasi
References
Manipuri cuisine
Fermented foods
Fermented fish
Fish sauces | Hentak | Biology | 237 |
7,792,030 | https://en.wikipedia.org/wiki/Urine%20collection%20device | A urine collection device or UCD is a device that allows the collection of urine for analysis (as in medical or forensic urinalysis) or for purposes of simple elimination (as in vehicles engaged in long voyages and not equipped with toilets, particularly aircraft and spacecraft). UCDs of the latter type are sometimes called piddle packs.
Similar devices are used, primarily by men, to manage urinary incontinence. These devices are attached to the outside of the penile area and direct urine into a separate collection chamber such as a leg or bedside bag. There are several varieties of external urine collection devices on the market today including male external catheters also known as urisheaths or Texas/condom catheters, urinals and hydrocolloid-based devices.
External products should not be used by any individual who experiences urinary retention without overflow incontinence.
Description
A urine collection device allows an individual to empty their bladder into a container hygienically and without spilling urine.
Condom catheters
Condom catheters, also known as male external catheters, urisheaths, or Texas catheters, are made of silicone or latex (depending on the brand/manufacturer) and cover the penis just like a condom but with an opening at the end to allow the connection to the urine bag. The sheath is worn over the penis and looks like a condom (hence the name). It stays in place by use of an adhesive, that can either be built into the sheath or come as a separate adhesive liner. The urine gets funneled away from the body, keeping the skin dry at all times. The urine runs into a urine bag that is attached at the bottom of the external catheter. During the day, a drainable leg bag can be used, and at night it is recommended to use a large-capacity bedside drainage bag. Male external catheters are designed to be worn 24/7 and changed daily – and can be used by men with both light and severe incontinence. Male external catheters come in several sizes and lengths to accommodate anatomical variation.
It is very important that the male external catheter/urisheath fits well – both the diameter and the length. Different manufacturers have small measuring guides that can be used to measure what size is needed before ordering a sample. If the user does not get measured correctly leakage and skin irritation can occur.
Urinals
Urinals are a class of device that does not attach to the body. Instead, these external collection systems can be placed against the urinary opening during voiding and removed once voiding is complete. These are commonly used by hunters and sportsmen who may spend long periods away from a bathroom. These are not appropriate for men with urinary retention or who experience involuntary urine leakage.
Use
Managing incontinence
Penile external catheters/urisheaths combined with urine bags are preferred over absorbent products – in particular when it comes to 'limitations to daily activities'. Advantages also include discretion, less water retention at the skin surface, and the potential for 24 hour use. Complications can increase in severity and frequency over time. Up to 40% of condom catheter users will develop a urinary tract infection with long-term use. 15% of long term users may develop skin injuries, including inflammation, ulceration, necrosis, gangrene and constriction of the penis. Sizing can also prove difficult for some men, leading to dislodgement of the catheter and urine spillage during voiding (commonly referred to as pop-offs or blow-offs). 1.3% of condom catheter users will develop a bladder or renal stone requiring medical treatment. While the line of causation is not well established, urinary retention from inefficient elimination while catheterized may allow more mineral buildup and encourage crystal growth.
Urinalysis
Special UCDs exist for the collection of urine samples for subsequent urinalysis. They range from a simple plastic cup to elaborate devices designed to collect specific volumes or types of urine samples at various points in the micturition process.
Aircraft pilots
A common use of UCDs is in military fighter aircraft. Small aircraft such as fighter planes are not equipped with toilets, but pilots are sometimes required to fly them for several hours continuously. Since most people produce enough urine to fill their bladders after only a few hours under normal conditions, some method must be provided to allow a pilot to urinate without leaving their seat in the cockpit. A UCD makes this possible. UCDs are also used on spacecraft and occasionally in other vehicles, for the same reasons.
A typical UCD consists of a small container with a dehydrated sponge inside, connected to a tube that in turn is connected to a funnel-like orifice that is adapted to the user's anatomy. The user simply holds the funnel near or on their urethral opening and urinates into the tube, with the collected urine saturating the sponge (which may be impregnated with disinfectants and odor-control substances) and filling the container. UCDs are designed to be used in cramped quarters without requiring that the user rise from his seated position in the cockpit. In most cases, the user wears special clothing that can easily be opened to permit use of the UCD (e.g., special zippers in flight suits).
, technologies that did not require opening of the flight suit began to emerge, such as the "Advanced Mission Extender Device" (AMXD), which includes a pump for draining urine into a collection bag.
Spaceflight
The first American crewed mission did not utilise a urine collection device, with NASA having passed over the idea, as the MR-3 flight was expected to be too short for it to be necessary. Astronaut Alan Shepard faced a lengthy delay on the launchpad however, and was forced to urinate in his pressure suit. This short-circuited electrodes that had been designed to measure vital signs. A purpose built system was in place for MR-5 utilising a condom and an external storage container. Similar systems have been used in spaceflight since.
Stadium buddy
A stadium buddy is an apparatus that consists of a collecting bag fastened around the leg and tubing that attaches to a condom catheter. The hood attaches over the penis but, unlike a condom, has a plug for the tube where the condom's reservoir tip would normally be. This apparatus allows an individual to "conveniently" urinate without having to make use of a restroom. Stadium buddies have been used by sports and concert attendees for over two decades, and are also used by pilots when flying aircraft too small to carry a restroom. Some aircraft have a tube in the seat for attaching to the condom catheter, and this tube drains out the bottom of the aircraft in flight.
See also
Invasive methods of urine collection:
Urinary catheterization
Suprapubic cystostomy
P-valve
References
External links
David Sedaris reads his essay about the Stadium Pal (Stadium Pal is a brand of stadium buddy.)
GeeWhiz catheters (a brand)
Medical equipment
Urine
Urinary incontinence
Urology | Urine collection device | Biology | 1,505 |
224,248 | https://en.wikipedia.org/wiki/Wallace%E2%80%93Bolyai%E2%80%93Gerwien%20theorem | In geometry, the Wallace–Bolyai–Gerwien theorem, named after William Wallace, Farkas Bolyai and P. Gerwien, is a theorem related to dissections of polygons. It answers the question when one polygon can be formed from another by cutting it into a finite number of pieces and recomposing these by translations and rotations. The Wallace–Bolyai–Gerwien theorem states that this can be done if and only if two polygons have the same area.
Wallace had proven the same result already in 1807.
According to other sources, Bolyai and Gerwien had independently proved the theorem in 1833 and 1835, respectively.
Formulation
There are several ways in which this theorem may be formulated. The most common version uses the concept of "equidecomposability" of polygons: two polygons are equidecomposable if they can be split into finitely many triangles that only differ by some isometry (in fact only by a combination of a translation and a rotation). In this case the Wallace–Bolyai–Gerwien theorem states that two polygons are equidecomposable if and only if they have the same area.
Another formulation is in terms of scissors congruence: two polygons are scissors-congruent if they can be decomposed into finitely many polygons that are pairwise congruent. Scissors-congruence is an equivalence relation. In this case the Wallace–Bolyai–Gerwien theorem states that the equivalence classes of this relation contain precisely those polygons that have the same area.
Proof sketch
The theorem can be understood in a few steps. Firstly, every polygon can be cut into triangles. There are a few methods for this. For convex polygons one can cut off each vertex in turn, while for concave polygons this requires more care. A general approach that works for non-simple polygons as well would be to choose a line not parallel to any of the sides of the polygon and draw a line parallel to this one through each of the vertices of the polygon. This will divide the polygon into triangles and trapezoids, which in turn can be converted into triangles.
Secondly, each of these triangles can be transformed into a right triangle and subsequently into a rectangle with one side of length 1. Alternatively, a triangle can be transformed into one such rectangle by first turning it into a parallelogram and then turning this into such a rectangle. By doing this for each triangle, the polygon can be decomposed into a rectangle with unit width and height equal to its area.
Since this can be done for any two polygons, a "common subdivision" of the rectangle in between proves the theorem. That is, cutting the common rectangle (of size 1 by its area) according to both polygons will be an intermediate between both polygons.
Notes about the proof
First of all, this proof requires an intermediate polygon. In the formulation of the theorem using scissors-congruence, the use of this intermediate can be reformulated by using the fact that scissor-congruences are transitive. Since both the first polygon and the second polygon are scissors-congruent to the intermediate, they are scissors-congruent to one another.
The proof of this theorem is constructive and doesn't require the axiom of choice, even though some other dissection problems (e.g. Tarski's circle-squaring problem) do need it. In this case, the decomposition and reassembly can actually be carried out "physically": the pieces can, in theory, be cut with scissors from paper and reassembled by hand.
Nonetheless, the number of pieces required to compose one polygon from another using this procedure generally far exceeds the minimum number of polygons needed.
Degree of decomposability
Consider two equidecomposable polygons P and Q. The minimum number n of pieces required to compose one polygon Q from another polygon P is denoted by σ(P,Q).
Depending on the polygons, it is possible to estimate upper and lower bounds for σ(P,Q). For instance, Alfred Tarski proved that if P is convex and the diameters of P and Q are respectively given by d(P) and d(Q), then
If Px is a rectangle of sides a·x and a·(1/x) and Q is a square of side length a, then Px and Q are equidecomposable for every x > 0. An upper bound for σ(Px,Q) is given by
Since σ(Px,Q) = σ(P(1/x),Q), we also have that
Generalisations
The analogous statement about polyhedra in three dimensions, known as Hilbert's third problem, is false, as proven by Max Dehn in 1900. The problem has also been considered in some non-Euclidean geometries. In two-dimensional hyperbolic and spherical geometry, the theorem holds. However, the problem is still open for these geometries in three dimensions.
References
External links
Wallace–Bolyai–Gerwien Theorem
Scissors Congruence - An interactive demonstration of the Wallace–Bolyai–Gerwien theorem.
Video showing a sketch of the proof
An Example of the Bolyai–Gerwien Theorem by Sándor Kabai, Ferenc Holló Szabó, and Lajos Szilassi, the Wolfram Demonstrations Project.
A presentation about Hilbert's third problem at College of Staten Island CUNY - Abhijit Champanerkar.
Optimal dissection of a unit square in a rectangle
Euclidean plane geometry
Theorems in discrete geometry
Geometric dissection | Wallace–Bolyai–Gerwien theorem | Mathematics | 1,234 |
67,976,248 | https://en.wikipedia.org/wiki/HD%2033266 | HD 33266 (HR 1675) is a solitary star in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 6.17, making it faintly visible to the naked eye. Located 481 light years away, it is approaching the Sun with a heliocentric radial velocity of .
HD 33266 is an A-type star with 2.45 times the mass of the Sun and 3.14 times the radius of the Sun. It shines at from its photosphere at an effective temperature of 8,952 K, giving it a white glow. Due to HD 33266 being an Am star, it spins slowly with a projected rotational velocity of at an age of 340 million years. Its metallicity − elements heavier than helium − is at solar level.
Note
References
Camelopardalis
A-type stars
33266
024313
1675
Durchmusterung objects | HD 33266 | Astronomy | 185 |
31,004,269 | https://en.wikipedia.org/wiki/Sporathylacium | Sporathylacium was a genus of land plant known from its bivalved sporangia. It is known from charcoalified Early Devonian deposits, its type locality being the Brown Clee Hill lagerstätten. It was listed as a rhyniophyte by Hao and Xue in 2013.
References
Enigmatic plant taxa
Prehistoric plant genera | Sporathylacium | Biology | 76 |
8,696,119 | https://en.wikipedia.org/wiki/Ultraviolet%20photoelectron%20spectroscopy | Ultraviolet photoelectron spectroscopy (UPS) refers to the measurement of kinetic energy spectra of photoelectrons emitted by molecules that have absorbed ultraviolet photons, in order to determine molecular orbital energies in the valence region.
Basic theory
If Albert Einstein's photoelectric law is applied to a free molecule, the kinetic energy () of an emitted photoelectron is given by
where h is the Planck constant, ν is the frequency of the ionizing light, and I is an ionization energy for the formation of a singly charged ion in either the ground state or an excited state. According to Koopmans' theorem, each such ionization energy may be identified with the energy of an occupied molecular orbital. The ground-state ion is formed by removal of an electron from the highest occupied molecular orbital, while excited ions are formed by removal of an electron from a lower occupied orbital.
History
Before 1960, virtually all measurements of photoelectron kinetic energies were for electrons emitted from metals and other solid surfaces. In about 1956, Kai Siegbahn developed X-ray photoelectron spectroscopy (XPS) for surface chemical analysis. This method uses x-ray sources to study energy levels of atomic core electrons, and at the time had an energy resolution of about 1 eV (electronvolt).
The ultraviolet photoelectron spectroscopy (UPS) was pioneered by Feodor I. Vilesov, a physicist at St. Petersburg (Leningrad) State University in Russia (USSR) in 1961 to study the photoelectron spectra of free molecules in the gas phase. The early experiments used monochromatized radiation from a hydrogen discharge and a retarding potential analyzer to measure the photoelectron energies.
The PES was further developed by David W. Turner, a physical chemist at Imperial College in London and then at Oxford University, in a series of publications from 1962 to 1967. As a photon source, he used a helium discharge lamp that emits a wavelength of 58.4 nm (corresponding to an energy of 21.2 eV) in the vacuum ultraviolet region. With this source, Turner's group obtained an energy resolution of 0.02 eV. Turner referred to the method as "molecular photoelectron spectroscopy", now usually "ultraviolet photoelectron spectroscopy" or UPS. As compared to XPS, UPS is limited to energy levels of valence electrons, but measures them more accurately. After 1967, commercial UPS spectrometers became available. One of the latest commercial devices was the Perkin Elmer PS18. For the last twenty years, the systems have been homemade. One of the latest in progress – Phoenix II – is that of the laboratory of Pau, IPREM developed by Dr. Jean-Marc Sotiropoulos.
Application
The UPS measures experimental molecular orbital energies for comparison with theoretical values from quantum chemistry, which was also extensively developed in the 1960s. The photoelectron spectrum of a molecule contains a series of peaks each corresponding to one valence-region molecular orbital energy level. Also, the high resolution allowed the observation of fine structure due to vibrational levels of the molecular ion, which facilitates the assignment of peaks to bonding, nonbonding or antibonding molecular orbitals.
The method was later extended to the study of solid surfaces where it is usually described as photoemission spectroscopy (PES). It is particularly sensitive to the surface region (to 10 nm depth), due to the short range of the emitted photoelectrons (compared to X-rays). It is therefore used to study adsorbed species and their binding to the surface, as well as their orientation on the surface.
A useful result from characterization of solids by UPS is the determination of the work function of the material. An example of this determination is given by Park et al. Briefly, the full width of the photoelectron spectrum (from the highest kinetic energy/lowest binding energy point to the low kinetic energy cutoff) is measured and subtracted from the photon energy of the exciting radiation, and the difference is the work function. Often, the sample is electrically biased negative to separate the low energy cutoff from the spectrometer response.
Gas discharge lines
Outlook
UPS has seen a considerable revival with the increasing availability of synchrotron light sources that provide a wide range of monochromatic photon energies.
See also
Angle resolved photoemission spectroscopy (ARPES)
Photoelectron photoion coincidence spectroscopy (PEPICO)
Time-resolved two-photon photoelectron spectroscopy
References
Emission spectroscopy
Surface science
Electron spectroscopy
Soviet inventions | Ultraviolet photoelectron spectroscopy | Physics,Chemistry,Materials_science | 932 |
77,714,151 | https://en.wikipedia.org/wiki/Cheyava%20Falls | Cheyava Falls is a rock discovered on Mars by NASA's Perseverance rover during its exploration of the Jezero Crater. This rock, named after a Grand Canyon waterfall, has drawn significant attention due to its potential as an indicator of ancient life on Mars. The rover's instruments detected organic compounds within the rock, which are essential for all known life. According to NASA, Cheyava Falls "possesses qualities that fit the definition of a possible indicator of ancient life".
"Cheyava Falls" is characterized by large white calcium sulfate veins and bands of reddish material, indicative of hematite, a mineral that gives Mars its rusty color. The veins are "filled with millimeter-size crystals of olivine". The rock features millimeter-sized off-white splotches surrounded by black material, resembling "leopard spots." These spots contain iron and phosphate, elements often associated with microbial life. According to a seven-step scale called Confidence of Life Detection (CoLD) used by NASA astrobiologists, the rock is on Step One, "Detect possible signal".
The rock's composition suggests it was once exposed to water. However, there are alternative, non-biological explanations for its features. The rover has analyzed the rock using various instruments but its team concludes that a definitive understanding will require returning the sample to Earth for more in-depth study.
The "arrowhead-shaped rock" was found at the northern edge of Neretva Vallis area, on July 18, 2024, and is 1 meter by 0.6 meters. On July 21, Perseverance took a sample of the rock that became its 22nd core sample that can be delivered to Earth by a future mission. The rover made a "selfie" with a rock on July 23.
Gallery
References
Mars 2020
Rocks on Mars
Astrobiology | Cheyava Falls | Astronomy,Biology | 378 |
3,287,020 | https://en.wikipedia.org/wiki/Shared%20space | Shared space is an urban design approach that minimises the segregation between modes of road user. This is done by removing features such as curbs, road surface markings, traffic signs, and traffic lights. Hans Monderman and others have suggested that, by creating a greater sense of uncertainty and making it unclear who has priority, drivers will reduce their speed, in turn reducing the dominance of vehicles, reducing road casualty rates, and improving safety for other road users.
Shared space design can take many different forms depending on the level of demarcation and segregation between different transportation modes. Variations of shared space are often used in urban settings, especially those that have been made nearly car-free (), and as part of living streets within residential areas. As a separate concept, "shared space" normally applies to semi-open spaces on busier roads, and here it is controversial.
Shared space is often opposed by organisations representing the interests of blind, partially sighted, and deaf people, who usually express a preference for the clear separation of pedestrian and vehicular traffic.
History
The origin of the term is generally linked with the work of Dutch traffic engineer Hans Monderman, who pioneered the method in the Dutch province of Friesland. Prior to the adoption of the term, street design projects carried out in Chambéry, France, by Michel Deronzier from the 1980s used the term "pedestrian priority". The term was used by Tim Pharoah to describe informal street layouts with no traffic demarcation (for example "Traffic Calming Guidelines", Devon County Council, 1991).
The term has been widely applied, especially by Ben Hamilton-Baillie, since the preparation of a European co-operation project in 2003. The European Shared Space project (part of the Interreg IIIB-North Sea programme) developed new policies and methods for the design of public spaces with streets between 2004 and 2008 under the leadership of Hans Monderman until his death in 2008.
In 2014, a review of the evolution of the shared space concepts was offered in Transport Reviews: A Transnational Transdisciplinary Journal.
The Chartered Institution of Highways and Transportation has identified three broad types of street design approach that have been called shared space but which have a number of important differences. They suggest that the term "shared space" should be replaced by three new labels: pedestrian prioritised streets, informal streets and enhanced streets.
Philosophy and support
The goal of shared space is to improve the road safety and vibrancy of roads and junctions, particularly ones with high levels of pedestrian traffic, by encouraging negotiation of priority in shared areas between different road users. Shared space is a "design approach rather than a design type characterised by standard features".
Hans Monderman suggested that an individual's behaviour in traffic is more positively affected by the built environment of the public space than by conventional traffic control devices and regulations. A reason for the apparent paradox that reduced regulation leads to safer roads may be found by studying the risk compensation effect.
"We're losing our capacity for socially responsible behaviour...The greater the number of prescriptions, the more people's sense of personal responsibility dwindles." (Der Spiegel quotes Monderman)
"When you don't exactly know who has right of way, you tend to seek eye contact with other road users. You automatically reduce your speed, you have contact with other people and you take greater care."
Such schemes are claimed to have had positive effect on road safety, traffic volume, economic vitality, and community cohesion where a user's behaviour becomes influenced and controlled by natural human interactions rather than by artificial regulation. Monderman has stated that objections are more a matter of communication than design, stressing the importance of consulting all relevant groups during the design stage.
The UK's Department for Transport issued national guidance on shared space in 2011. However in July 2018 it reversed its position and instructed local authorities to halt all new shared space projects, with Transport Minister Nusrat Ghani stating they "just don't work" for blind and partially-sighted people.
Criticism
Reviewing the research that underpinned national policy in the UK, in 2011, Moody and Melia found that some of the claims made for shared space schemes were not justified by the evidence—particularly the claims that pedestrians are able to follow desire lines, and that shared space reduces traffic speeds. Their primary research in Ashford, Kent, suggested that in streets with high volumes of traffic, pedestrians are more likely to give way to vehicles than vice versa. Most people, but particularly women and older people, found the shared space intimidating and preferred the previous layout with conventional crossings. A study by Hammond and Musselwhite using a case study of Widemarsh Street in Hereford found that if traffic volume was relatively low and speeds of vehicles slow anyway, then vulnerable road users found it easier to share the area with vehicles, including those blind or partially sighted and older people with mobility impairments.
There are wide-ranging reservations about the practicality of the shared space philosophy where it involves the removal of features such as kerbs. In a 2006 report from the Associated Press, it was commented that traditionalists in town planning departments say the schemes rob the motorists of vital information, and reported that a spokesman for Royal National Institute of Blind People criticised the removal of familiar features such as railings, kerbs, and barriers. Shared space is opposed by many organisations representing blind, partially sighted and deaf people. Some of their members avoid shared space areas entirely. Shared surfaces, which are generally used in shared space schemes, can cause concern for the blind and partially sighted who cannot visually negotiate their way with other road users, as the lack of separation implicit in these features has also removed their safe space. The UK's Guide Dogs for the Blind Associations "Say No to Shared Streets" campaign has the support of more than thirty other disability organisations. There have been similar concerns raised by other groups representing disabled people, including Leonard Cheshire Disability, the Royal National Institute for Deaf People, and Mencap, who have noted problems when negotiating a route with motor vehicle users, leading them to challenge its fundamental premise. Lord Holmes' 2015 report Accidents by Design found that sixty-three per cent of respondents reported a negative experience of shared space, and thirty-five per cent said they actively avoided it. Lord Holmes attacked the concept as a recipe for "confusion, chaos and catastrophe". The Holmes report also noted serious issues for wheelchair users "Respondents who used wheelchairs stated that it was virtually impossible to locate a safe crossing point on roads with shared space." In July 2018, the UK DfT reversed its position on shared spaces due to the risk to disabled people, with Transport Minister Nusrat Ghani stating "they just don't work".
The Dutch Fietsberaad (Centre of Expertise on Bicycle Policy) has demonstrated ambivalence over shared space schemes, describing some benefits but also some drawbacks for the less assertive cyclist. Fietsberaad has noted that shared space has decreased car speeds but that "some cyclists do not dare take priority. Instead, they dismount and wait for priority to be clearly given, then walk or ride across the intersection. A problem may be that they are met halfway by cars from the other direction and must rely on the drivers to give way of their own volition. Owing to low speeds and the cyclists' defensive behaviour this crossing strategy need not be unsafe in itself, but it most certainly is not convenient."
In New Zealand, concerns about such limitations of the shared space concept have led, in cooperation with disability organisations, to the introduction of vehicle- and obstruction-free corridors ("accessible zones") along the building lines (i.e., in the areas where footpaths would normally be located), to provide a safe route in the shared spaces being introduced.
Nearly car free
The British Transport Research Laboratory found that below flows of 90 vehicles per hour adult pedestrians were prepared to mingle with traffic. When flows reached 110 vehicles per hour, they used the width between frontages as if it were a traditional road. A similar value is used to define suitability for a woonerf.
Examples
Numerous towns and cities around the world have implemented schemes with elements based on the shared space principles.
Australia
Bendigo, Victoria, plans (as of October 2007) to implement shared space in its city centre. The Streets as Shared Spaces program supported 65 councils across New South Wales in developing shared spaces, since its launch in May 2020.
Austria
In October 2011, Graz opened a shared space zone around a five-point intersection known as Sonnenfelsplatz next to the University of Graz with the intention of easing congestion from 4 separate city bus lines and auto, bike and pedestrian traffic as well as reducing the number of accidents. This was the first shared space concept for Austria.
Denmark
Ejby introduced a shared space project in Denmark. It was part of the European Interreg IIIB project with Province of Fyslän as lead partner. The project was led by urban planner Morten Mejsen Westergaard and Bjarne Winterberg. It was supervised by Hans Monderman.
Germany
Bohmte introduced a shared space road system in September 2007. One of project's goals was to improve road safety in the town.
Netherlands
Makkinga has no road markings and no signs giving an order or direction signs visible in the streets. There is a traffic sign at the entrance to the town that reads Verkeersbordvrij, meaning "free of traffic signs". Parking meters and stopping restrictions are also absent. Drachten is another pioneer town for such schemes. Accident figures at one junction where traffic lights were removed have dropped from thirty-six in the four years prior to the introduction of the scheme to two in the two years following it. Only three of the original fifteen sets of traffic lights remain. Tailbacks (traffic jams) are now almost unheard of at the town's main junction, which handles about 22,000 cars a day.
An evaluation of the Laweiplein scheme in Drachten, which replaced a set of traffic lights with an open square with a roundabout and pedestrian crossings, concluded that traffic now flows at a constant rate, at equal speeds for motor and bicycle traffic, and more freely with reduced congestion, shorter delays and improved capacity including for pedestrians. The evaluation states that there has been a reduction in recorded accidents, but cyclist and motorist perceptions of traffic safety have slightly declined. This is in accordance with theories of how shared spaces work by creating uncertainty. Meanwhile, pedestrian perceptions of traffic safety seem to have remained the same.
New Zealand
Several of Auckland's streets have been turned into shared spaces. These include Elliot and Darby Streets, Lorne street, the Fort street areas, all near Queen Street, Auckland and Federal Street by the Skytower. However, Auckland's first shared space is Wairepo Swamp Walk, completed mid-2010. Wairepo Swamp Walk is one of a number of transport infrastructure projects improving transport services around Eden Park as part of the 2011 Rugby World Cup. A research study has been undertaken by Auckland Transport in conjunction with the University of Auckland to evaluate city centre shared spaces in the Auckland CBD.
Sweden
Since the zebra crossings and traffic signs were replaced with a spacious fountain, benches, and other street furniture, the Skvallertorget square in Norrköping has experienced no accidents, mean traffic speeds have dropped from 21 to 16 km/h (13 to 10 mph) and liveability has increased.
Switzerland
The concept of a shared space where no right of way is defined for all participants is presently not legally possible. The Strassenverkehrsgesetz (SVG) requires that at least one of the participants has a right of way. As a result, the Swiss concept of Begegnungszone has become popular. However here pedestrians have right of way.
United Kingdom
In London, Exhibition Road was developed into a shared space in 2012 after a design competition in 2003, a court case, and numerous community consultations.
In Seven Dials, London, the road surface has been re-laid to remove the distinction between the roadway and the footway and kerbs have been lowered to encourage people to wander across the street. A scheme implemented in London's Kensington High Street, dubbed naked streets in the pressreflecting the removal of markings, signage and pedestrian barriershas yielded significant and sustained reductions in injuries to pedestrians. It is reported that, based on two years of 'before and after' monitoring, casualties fell from 71 in the period before the street was remodelled to 40 afterwardsa drop of 43%.
Gwynedd Council rebuilt the foreground to Caernarfon Castle. The scheme uses local slate and granite surfacing and high-quality street furniture, and a new fountain, intended to create a change in the behaviour of drivers.
Brighton City Council transformed the whole of New Road, adjacent to the Royal Pavilion, into a fully shared space designed by Landscape Projects and Gehl Architects, with no delineation of the carriageway except for subtle changes in materials. The route for vehicles along New Road is only suggested through the location of street furniture, such as public seating and street lights. The re-opening of the street has led to a 93% reduction in motor vehicle trips (12,000 fewer per day) and lower speeds (to around 10 MPH), alongside an increase in cyclist and pedestrian usage (93% and 162%, respectively).
In spring 2008, shared space was introduced in Ashford, Kent. The scheme replaced a section of Ashford's former four-lane ring road with two-way streets on which drivers, cyclists, and pedestrians have equal priority. Unnecessary street furniture, road markings and traffic lights have been removed and the speed limit cut to 20 mph.
The scheme has been claimed to have improved safety records. Between November 2008 and January 2011, there have been four road casualties there, resulting from the six reported accidents. Claims about the success of the Ashford scheme were called into question during 2011 by a study conducted by the University of the West of England.
Following the initial reports claiming a success for the Ashford scheme, other UK local councils planned to use a similar approach; these include Southend-on-Sea, Staines, Newcastle-under-Lyme, Hereford, and Edinburgh.
There have also been trials in Ipswich, with shared space being a key feature of the design of the new Ravenswood community being built on the site of the former Ipswich Airport.
At Princess Royal Square (formerly Pier Square) in Weston-super-Mare, the conventional road system has been replaced by a seafront open area. This has been complemented by the restoration of the Coalbrookdale fountain in its centre.
In Poynton, Cheshire, it was found that as well as providing significant safety improvements, and regenerating the retail and social centre, the road capacity was not reduced after the redevelopment of a busy junction in the town incorporated shared space elements. In the scheme, the redevelopment of a multi-lane signalised crossroads, with a traffic flow of 26,000 vehicles per day, which was completed in March 2012, traffic lanes, signals, road markings, road signs and street clutter were all removed. In the first three years after the redevelopment there was one minor personal injury accident, compared to 4-7 serious incidents in each of the three years leading up to the project. Although no speed limit changes were made, average traffic speeds fell to around 20 mph and there were reductions in vehicle journey times as well as reductions in pedestrian delays at the junction.
A pilot road layout project, which includes shared-space elements, is to be trialled in the Stobhill area of Morpeth, Northumberland. Opposition groups argue that the plans are unsafe for children and disabled people.
United States
In the United States, the shared space concept has become more popular in recent years.
In West Palm Beach, Florida, removal of traffic signals and road markings brought pedestrians into much closer contact with cars. The result has been slower traffic, fewer accidents, and shorter trip times.
In Savannah, Georgia, the Oglethorpe Plan has been adapted to accommodate pedestrian and vehicular traffic throughout a network of wards, each with a central square. The size and configuration of the squares restrains vehicular traffic to speeds under 20 miles per hour, a threshold speed beyond which shared space tends to break down.
In Salt Lake City, Utah the City Creek Center property was designed with a kerbless street and bollards. Following the success of this, the publicly owned side of Regent Street was redone to be kerbless as well.
Shared streets have also been installed in the New York City neighbourhoods of Jamaica, and Flatiron. In the Financial District, there are plans to remove curbs in areas that have been closed off to vehicular traffic since the 9/11 attacks.
In 2018, the Philadelphia region's Metropolitan Planning Organization DVRPC published a guide for engineers and policymakers Curbless Streets: Evaluating Curbless and Shared Space Concepts for Use on City of Philadelphia Streets. The US Federal Highway Administration has also issued a publication, Accessible Shared Streets: Notable Practices and Considerations for Accommodating Pedestrians with Vision Disabilities.
See also
General themes
Bicycle-friendly
Cyclability
Traffic calming
Traffic conflict
Tullock's spike
Proponents
John Adams, United Kingdom
David Engwicht, Australia
Martin Cassini, United Kingdom
Jan Gehl, Denmark
Eric Britton, France/USA
Project for Public Spaces, United States
References
External links
Shared space UK Department for Transport
Types of streets
Road safety
Traffic calming
Transport infrastructure
Transportation planning
Sustainable transport | Shared space | Physics | 3,596 |
42,564,321 | https://en.wikipedia.org/wiki/SED-ML | The Simulation Experiment Description Markup Language (SED-ML) is a representation format, based on XML, for the encoding and exchange of simulation descriptions on computational models of biological systems. It is a free and open community development project.
SED-ML Level 1 Version 1, the first version of SED-ML, enables descriptions of time course simulation experiments.
Structure
The SED-ML format is built of five major blocks:
The Model entity is used to reference the models used in the simulation experiment and to define pre-processing procedures on these models before simulation. Models must be in standard representation formats (e.g., SBML, CellML, NeuroML). Examples for pre-processing are, e.g., changing the value of an observable, computing the change of a value using mathematics, or general changes on any XML element of the model representation.
The Simulation entity contains all information about the simulation settings and the steps taken during simulation, e.g., the particular type of simulation and the algorithm used for the execution of the simulation. The simulation algorithm is specified with a Kinetic Simulation Algorithm Ontology term.
The Task entity applies one of the defined simulations with one of the referenced models at a time.
The DataGenerator entity encodes post-processing procedures which need to be applied to the simulation result before output, e.g., normalisation of data.
The Output entity specifies the simulation output, e.g., the particular plots to be shown.
More information on the SED-ML structure is available from the SED-ML home page and the reference publication.
History
The idea of developing a standard format for simulation experiment encoding was born at the European Bioinformatics Institute (EMBL-EBI). In 2007, Dagmar Waltemath and Nicolas Le Novère started to draft such a format during Dagmar's Marie-Curie funded internship in the Computational Neuroscience group at EMBL-EBI.
The SED-ML project was first discussed publicly at the 12th SBML Forum Meeting in 2007, in Long Beach (US). The first version of SED-ML was then presented at the "Super-hackathon "standards and ontologies for Systems Biology"" in Okinawa in 2008. Back then, the language was called MIASE-ML (in accordance with the MIASE guidelines). In Okinawa, many researchers showed a high interest in the format, and discussions were vital. MIASE became the Minimum Information guideline for simulation experiments. MIASE-ML was renamed into "Simulation Experiment Description Markup Language" (SED-ML).
Level 1 Version 1 of SED-ML officially appeared in March 2011, but SED-ML was presented, discussed and further specified during several community meetings in the years in between, including the combined "CellML-SBGN-SBO-BioPAX-MIASE workshop" in 2009, or the "2010 SBML-BioModels.net Hackathon".
Since then SED-ML has been developed in collaboration with the communities forming the "computational modeling in biology network" COMBINE. Besides dedicated sessions at various meetings, the development of SED-ML benefits from community interactions on the SED-ML-discuss mailing list.
SED-ML Community
SED-ML is part of the COmputational Modeling in Biology Network (COMBINE). Format development is coordinated by an editorial board elected by the community. Discussions take place at SED-ML-discuss.
References
Science and technology in Cambridgeshire
South Cambridgeshire District
Systems biology
XML markup languages | SED-ML | Biology | 734 |
2,447,975 | https://en.wikipedia.org/wiki/Colonisation%20%28biology%29 | Colonisation or colonization is the spread and development of an organism in a new area or habitat. Colonization comprises the physical arrival of a species in a new area, but also its successful establishment within the local community. In ecology, it is represented by the symbol λ (lowercase lambda) to denote the long-term intrinsic growth rate of a population.
Surrounding theories and applicable process have been introduced below. These include dispersal, colonisation-competition trade off and prominent examples that have been previously studied.
One classic scientific model in biogeography posits that a species must continue to colonize new areas through its life cycle (called a taxon cycle) in order to persist. Accordingly, colonisation and extinction are key components of island biogeography, a theory that has many applications in ecology, such as metapopulations. Another factor included in this scientific model is the competition-colonisation trade off. This idea goes into the driving factors of colonisation through many species that all share a need to expand.
Scale
Colonisation occurs on several scales. In the most basic form, as biofilm in the formation of communities of microorganisms on surfaces.
This microbiological colonisation also takes place within each animal or plant and is called microbiome.
In small scales such as colonising new sites, perhaps as a result of environmental change. And on larger scales where a species expands its range to encompass new areas. This can be through a series of small encroachments, such as in woody plant encroachment, or by long-distance dispersal. The term range expansion is also used.
Dispersal
Dispersion in biology is the dissemination, or scattering, of organisms over periods within a given area or over the Earth. The dispersion of species into new locations can be inspired by many causes. Often times species naturally disperse due to physiological adaptations which allows for a higher survival rate of progeny in new ecosystems. Other times these driving factors are environmentally related, for example global warming, disease, competition, predation. Dispersion of different species can come in many forms. Some prime examples of this is flight of species across long distances, wind dispersal of plant and fungi progeny, long distance of travel in packs, etc.
Competition-Colonisation Trade-off
The competition-colonisation trade-off refers to a driving factor that has a large influence over diversity and how it is maintained in a community. This is considered a driving factor because all species have to make a decision to entertain competition with others in the community or disperse from the community in hopes of a more optimal environment. This can span from available nutrient sources, light exposure, oxygen availability, reproduction competition, etc.. These trade offs are critical in the explanation of colonisation and why it happens.
Use
The term is generally only used to refer to the spread of a species into new areas by natural means, as opposed to unnatural introduction or translocation by humans, which may lead to invasive species.
Colonisation events
Large-scale notable pre-historic colonisation events include:
Arthropods
the colonisation of the Earth's land by the first animals, the arthropods. The first fossils of land animals come from millipedes. These were seen about 450 million years ago.
Humans
the early human migration and colonisation of areas outside Africa according to the recent African origin paradigm, resulting in the extinction of Pleistocene megafauna, although the role of humans in this event is controversial.
Birds
the colonisation of the New World by the cattle egret and the little egret
the colonisation of Britain by the little egret
the colonisation of western North America by the barred owl
the colonisation of the East Coast of North America by the Brewer's blackbird
the colonisation-westwards spread across Europe of the collared dove
the spread across the eastern USA of the house finch
the expansion into the southern and western areas of South Africa by the Hadeda Ibis
Reptiles
the colonisation of Anguilla by Green iguanas following a rafting event in 1995
the colonisation of Burmese pythons into the Florida Everglades. The release of snakes came from the desire to breed them and sell them as exotic pets. As they grew people became unable to care for the animals and began to release them into the Everglades.
Dragonflies
the colonisation of Britain by the small red-eyed damselfly
Moths
the colonisation of Britain by Blair's shoulder-knot
Land Vertebrates
The colonisation of Madagascar by land-bound vertebrates.
Plants
The colonisation of Pinus species through wind dispersion.
See also
Colony (biology)
Invasive species
Pioneer species
References
Further reading
Community ecology
Ecological processes
Ecology terminology | Colonisation (biology) | Physics,Biology | 959 |
458,078 | https://en.wikipedia.org/wiki/Tholin | Tholins (after the Greek () "hazy" or "muddy"; from the ancient Greek word meaning "sepia ink") are a wide variety of organic compounds formed by solar ultraviolet or cosmic ray irradiation of simple carbon-containing compounds such as carbon dioxide (), methane () or ethane (), often in combination with nitrogen () or water (). Tholins are disordered polymer-like materials made of repeating chains of linked subunits and complex combinations of functional groups, typically nitriles and hydrocarbons, and their degraded forms such as amines and phenyls. Tholins do not form naturally on modern-day Earth, but they are found in great abundance on the surfaces of icy bodies in the outer Solar System, and as reddish aerosols in the atmospheres of outer Solar System planets and moons.
In the presence of water, tholins could be raw materials for prebiotic chemistry (i.e., the non-living chemistry that forms the basic chemicals of which life is made). Their existence has implications for the origins of life on Earth and possibly on other planets. As particles in an atmosphere, tholins scatter light, and can affect habitability.
Tholins may be produced in a laboratory, and are usually studied as a heterogeneous mixture of many chemicals with many different structures and properties. Using techniques like thermogravimetric analysis, astrochemists analyze the composition of these tholin mixtures, and the exact character of the individual chemicals within them.
Overview
The term "tholin" was coined by astronomer Carl Sagan and his colleague Bishun Khare to describe the difficult-to-characterize substances they obtained in his Miller–Urey-type experiments on the methane-containing gas mixtures such as those found in Titan's atmosphere. Their paper proposing the name "tholin" said:
For the past decade we have been producing in our laboratory a variety of complex organic solids from mixtures of the cosmically abundant gases , , , , HCHO, and . The product, synthesized by ultraviolet (UV) light or spark discharge, is a brown, sometimes sticky, residue, which has been called, because of its resistance to conventional analytical chemistry, "intractable polymer". [...] We propose, as a model-free descriptive term, 'tholins' (Greek Θολός, muddy; but also Θόλος, vault or dome), although we were tempted by the phrase 'star-tar'.
Tholins are not one specific compound but rather are descriptive of a spectrum of molecules, including heteropolymers, that give a reddish, organic surface covering on certain planetary surfaces. Tholins are disordered polymer-like materials made of repeating chains of linked subunits and complex combinations of functional groups. Sagan and Khare note "The properties of tholins will depend on the energy source used and the initial abundances of precursors, but a general physical and chemical similarity among the various tholins is evident."
Some researchers in the field prefer a narrowed definition of tholins, for example S. Hörst wrote: "Personally, I try to use the word 'tholins' only when describing the laboratory-produced samples, in part because we do not really know yet how similar the material we produce in the lab is to the material found on places like Titan or Triton (or Pluto!)." French researchers also use the term tholins only when describing the laboratory-produced samples as analogues. NASA scientists also prefer the word 'tholin' for the products of laboratory simulations, and use the term 'refractory residues' for actual observations on astronomical bodies.
Formation
Artificially
The key elements of tholins are carbon, nitrogen, and hydrogen. Laboratory infrared spectroscopy analysis of experimentally synthesized tholins has confirmed earlier identifications of chemical groups present, including primary amines, nitriles, and alkyl portions such as / forming complex disordered macromolecular solids. Laboratory tests generated complex solids formed from exposure of : gaseous mixtures to electrical discharge in cold plasma conditions, reminiscent of the famous Miller–Urey experiment conducted in 1952.
Naturally
As illustrated to the right, tholins are thought to form in nature through a chain of chemical reactions known as pyrolysis and radiolysis. This begins with the dissociation and ionization of molecular nitrogen () and methane () by energetic particles and solar radiation. This is followed by the formation of ethylene, ethane, acetylene, hydrogen cyanide, and other small simple molecules and small positive ions. Further reactions form benzene and other organic molecules, and their polymerization leads to the formation of an aerosol of heavier molecules, which then condense and precipitate on the planetary surface below.
Tholins formed at low pressure tend to contain nitrogen atoms in the interior of their molecules, while tholins formed at high pressure are more likely to have nitrogen atoms located in terminal positions.
Tholins may be a major constituent of the interstellar medium. On Titan, their chemistry is initiated at high altitudes and participates in the formation of solid organic particles.
These atmospherically-derived substances are distinct from ice tholin II, which are formed instead by irradiation (radiolysis) of clathrates of water and organic compounds such as methane () or ethane (). The radiation-induced synthesis on ice are independent of temperature.
Models show that, even when far from UV radiation of a star, cosmic ray doses may be fully sufficient to convert carbon-containing ice grains entirely to complex organics in less than the lifetime of the typical interstellar cloud.
Biological significance
Some researchers have speculated that Earth may have been seeded by organic compounds early in its development by tholin-rich comets, providing the raw material necessary for life to develop. (See Miller–Urey experiment for discussion.) Tholins do not exist naturally on present-day Earth due to the oxidizing properties of the free oxygen component of its atmosphere ever since the Great Oxygenation Event around 2.4 billion years ago.
Laboratory experiments suggest that tholins near large pools of liquid water that might persist for thousands of years could facilitate the formation of prebiotic chemistry to take place, and has implications for the origins of life on Earth and possibly other planets. Also, as particles in the atmosphere of an exoplanet, tholins affect the light scatter and act as a screen for protecting planetary surfaces from ultraviolet radiation, affecting habitability. Laboratory simulations found derived residues related to amino acids as well as urea, with important astrobiological implications.
On Earth, a wide variety of soil bacteria are able to use laboratory-produced tholins as their sole source of carbon. Tholins could have been the first microbial food for heterotrophic microorganisms before autotrophy evolved.
Occurrence
Sagan and Khare note the presence of tholins through multiple locations: "as a constituent of the Earth's primitive oceans and therefore relevant to the origin of life; as a component of red aerosols in the atmospheres of the outer planets and Titan; present in comets, carbonaceous chondrites asteroids, and pre-planetary solar nebulae; and as a major constituent of the interstellar medium." The surfaces of comets, centaurs, and many icy moons and Kuiper-belt objects in the outer Solar System are rich in deposits of tholins.
Moons
Titan
Titan tholins are nitrogen-rich organic substances produced by the irradiation of the gaseous mixtures of nitrogen and methane found in the atmosphere and surface of Titan. Titan's atmosphere is about 97% nitrogen, 2.7±0.1% methane and the remaining trace amounts of other gases. In the case of Titan, the haze and orange-red color of its atmosphere are both thought to be caused by the presence of tholins.
Europa
Colored regions on Jupiter's satellite Europa are thought to be tholins. The morphology of Europa's impact craters and ridges is suggestive of fluidized material welling up from the fractures where pyrolysis and radiolysis take place. In order to generate colored tholins on Europa there must be a source of materials (carbon, nitrogen, and water), and a source of energy to drive the reactions. Impurities in the water ice crust of Europa are presumed both to emerge from the interior as cryovolcanic events that resurface the body, and to accumulate from space as interplanetary dust.
Rhea
The extensive dark areas on the trailing hemisphere of Saturn's moon Rhea are thought to be deposited tholins.
Triton
Neptune's moon Triton is observed to have the reddish color characteristic of tholins. Triton's atmosphere is mostly nitrogen, with trace amounts of methane and carbon monoxide.
Dwarf planets
Pluto
Tholins occur on the dwarf planet Pluto and are responsible for red colors as well as the blue tint of the atmosphere of Pluto. The reddish-brown cap of the north pole of Charon, the largest of five moons of Pluto, is thought to be composed of tholins, produced from methane, nitrogen and related gases released from the atmosphere of Pluto and transferred over about distance to the orbiting moon.
Ceres
Tholins were detected on the dwarf planet Ceres by the Dawn mission. Most of the planet's surface is extremely rich in carbon, with approximately 20% carbon by mass in its near surface. The carbon content is more than five times higher than in carbonaceous chondrite meteorites analyzed on Earth.
Makemake
Makemake exhibits methane, large amounts of ethane and tholins, as well as smaller amounts of ethylene, acetylene and high-mass alkanes may be present, most likely created by photolysis of methane by solar radiation.
Kuiper belt objects and Centaurs
The reddish color typical of tholins is characteristic of many Trans-Neptunian objects, including plutinos in the outer Solar System such as 28978 Ixion. Spectral reflectances of Centaurs also suggest the presence of tholins on their surfaces. The New Horizons exploration of the classical Kuiper belt object 486958 Arrokoth revealed reddish color at its surface, suggestive of tholins.
Comets and asteroids
Tholins were detected in situ by the Rosetta mission to comet 67P/Churyumov–Gerasimenko. Tholins are not typically characteristic of main-belt asteroids, but have been detected on the asteroid 24 Themis.
Tholins beyond the Solar System
Tholins might have also been detected in the stellar system of the young star HR 4796A using the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) aboard the Hubble Space Telescope. The HR 4796 system is approximately 220 light years from Earth.
See also
References
Organic polymers
Origin of life
Astrochemistry
Prebiotic chemistry | Tholin | Chemistry,Astronomy,Biology | 2,235 |
60,133,827 | https://en.wikipedia.org/wiki/IKozie%20micro-home | The iKozie micro-home is a prefabricated home designed for one person and measures 17.25 square metres (186 sq ft).
It was designed by Kieran O’Donnell, a trustee of the Homeless Foundation, and Andrew Eastabrook of Eastabrook Architects.
The first iKozie micro-home was installed in the garden of the Homeless Foundation, on 29 August 2017.
iKozie Ltd was granted planning permission by Worcester City Council for a reduced number of 16 homes on 18 October 2018, following extensive reactive amendments to the original design in response to objections from local residents. Construction of the scheme is anticipated to start in 2019.
References
External links
Prefabricated houses
Housing in the United Kingdom
2017 introductions
Homelessness | IKozie micro-home | Engineering | 152 |
3,741,418 | https://en.wikipedia.org/wiki/The%20Path%20Between%20the%20Seas | The Path Between the Seas: The Creation of the Panama Canal, 1870–1914 (1977) is a book by the American historian David McCullough, published by Simon & Schuster. The 698-page book contains 80 photographs, two maps and extensive source references. It won the U.S. National Book Award in History, the Francis Parkman Prize, the Samuel Eliot Morison Award, and the Cornelius Ryan Award.
The book details people, places, and events involved in building the Panama Canal. The title refers to the connection between the Atlantic and Pacific oceans that the opening of the canal created.
Making extensive use of letters and interviews with participants and their surviving relatives, the author presents the personal side of the difficulties of the original French effort, and the massive financial losses caused by the failure of that effort; the American negotiations with Colombia, and the machinations that brought about the independence of Panama; and the personalities and conflicts of the principal players in the American effort. This personal aspect is set against the backdrop of the gigantic scale of the construction and the enormous technical difficulties that were surmounted to reach the eventual goal, the prospective benefit of which had long been recognized.
U.S. President Jimmy Carter has said that the treaties passing control of the Canal to Panama would not have passed the U.S Senate had it not been for McCullough's book. “All through the Senate debates on the issue,” McCullough observes, “the book was quoted again and again, and I’m pleased to say that it was quoted by both sides. Real history always cuts both ways."
See also
History of the Panama Canal
References
External links
Book in PDF and other formats.
1977 non-fiction books
20th-century history books
Books by David McCullough
History books about civil engineering in the United States
History books about France
History books about Panama
History books about the United States
National Book Award–winning works
Panama Canal
Simon & Schuster books | The Path Between the Seas | Engineering | 394 |
1,654,862 | https://en.wikipedia.org/wiki/Voit | Voit (official name: "Industrias Voit S.A. de C.V.") is a sports equipment manufacturing company based in Mexico. The company was founded by German American entrepreneur William J. Voit (1880–1946) of Worthington, Indiana. The current range of products by Voit includes balls (for association and American football, basketball and volleyball), and also goalkeeper gloves, tennis rackets, football uniforms, shin guards, and swimming equipment (suits, goggles, caps, and fins) and accessories (backpacks, bags).
History
Voit began in Los Angeles in 1922 as a tire retreading products factory. In the late 1920s Voit developed and patented the first full-molded, all-rubber inflatable ball and the first needle-type air retention valves. They also developed highly accurate pocket and wrist watches during this period.
In 1931, Voit developed and patented the first all-rubber athletic balls, including the process of vulcanization which allowed a material to be fixed onto a separate rubber bladder. In the same year, it changed names from the W. J. Voit Corporation to Voit Rubber Corporation.
Later in the 1930s, Voit developed the process of icosahedron winding, which allowed balls to be machine wound with nylon threads over the bladder, providing both strength and consistency in shape and permitting mass production by a machine process.
Those Voit patents and products made possible greatly increased athletic and recreation activity in the school systems, and led to universal use of a new type of product that now dominates sales in its field.
In 1957, the company was purchased by AMF.
Other developments and patents later in the 1950s and 1960s included:
The Swimaster line of professional dive equipment. Voit was one of the five original American diving gear makers: U.S. Divers, Healthways, "Voit", Dacor, Swimaster.
The Equi Staff line of professional golf equipment (which included the innovation of the "Power Plugs" or screws to adjust the balance of golf clubs).
The first rubber-bodied water polo ball (which was adopted as the official ball of college, international and Olympic competitions).
V-Shock, introduced in the late 1990s, was Voit's inexpensive alternative to the Casio G-Shock watches. They have since been discontinued.
Sponsorships
Voit has sponsored the following association football events and athletes:
Liga MX – official game ball and referee kits
Liga FPD – official game ball
Liga Nacional (until 2021)
Óscar Pérez Rojas
References
External links
Sportswear brands
Sporting goods manufacturers of the United States
Sporting goods manufacturers of Mexico
Manufacturing companies established in 1922
Underwater diving engineering
Greene County, Indiana
Manufacturing companies based in Mexico City
Mexican brands
1922 establishments in California
Underwater diving equipment manufacturers | Voit | Engineering | 565 |
68,820,503 | https://en.wikipedia.org/wiki/Transgene%20%28company%29 | Transgene S.A. is a French biotechnology company founded in 1979. It is based in Illkirch-Graffenstaden, near Strasbourg, Alsace. The company develops and manufactures immunotherapies for the treatment of cancer. Based on viral vectors, these therapies stimulate the immune defenses of patients to specifically target cancer cells.
Transgene has two technological platforms based on these respective approaches: individual therapeutic vaccines, shared antigens cancer vaccines oncolytic viruses.
Transgene’s portfolio consists of four products currently in clinical development. Its lead product TG4050, a neoantigen individualized therapeutic cancer vaccine is currently being developed in a randomized Phase I/II trial in the adjuvant treatment of head and neck cancer.
The company is listed on the regulated market of Euronext in Paris.
History
Transgene was founded in 1979, on the initiative of Pierre Chambon and Philippe Kourilsky. Jean-Pierre Lecocq was the first Scientific Director of Transgene in 1980.
Dr Alessandro Riva, MD, joined Transgene in 2022 as Chairman of the Board of Directors. In May 2023 the board appointed him Chairman adn Chief Executive Officer of the company,.
Technological platforms
Transgene owns two technological platforms:
Invir.IO is a technology platform based on the patented oncolytic viruses that replicate only in cancer cells. The genome of these viruses has been modified to express anti-tumor therapies directly within the tumor.
The myvac® platform is based on an MVA vector which safety, biological activity and ability to induce an immune response against tumor antigens are established and recognized. The platform enables the design of personalized viruses based on each patient’s tumor mutations. Transgene selects around 30 neoantigens per patient, based on the AI of its partner NEC, and then encodes them into viral DNA.
Products in development
The Company has several clinical-stage products in its portfolio.
1- TG4050 : This neoantigen individualized therapeutic cancer vaccine is currently being developed in a randomized Phase I/II trial in the adjuvant treatment of head and neck cancer.
2- TG4001 : is a therapeutic vaccine designed to express the E6 and E7 antigens of the HPV-16 virus (human papillomavirus type 16). Transgene is currently evaluating the full study results in detail to determine the best way forward for this program.
3- Oncolytic viruses: TG6050 and BT-001. Transgene’s oncolytic viruses are designed to directly and selectively destroy the cancer cells by using an oncolysis mechanism, while also inducing immune responses against tumor cells. In addition, during their replication, the virus expresses the payloads integrated in its genome and therefore allows the expression of immunomodulators and/or therapeutic agents specifically in the tumors,,,,.
4- Transgene and AstraZeneca have been collaborating since 2019 to co-develop oncolytic viruses from the Invir.IO™ platform.
Management Committee
Transgene’s Management Committee is composed of the following members:
Alessandro Riva, Chairman & Chief Executive Officer (CEO)
Hedi Ben Brahim, Chairman & Chief Executive Officer (CEO);
Éric Quéméneur, Executive Vice-President, Chief Scientific Officer (CSO);
Christophe Ancel, Vice-President Pharmaceutical Operations & Qualified Pharmacist;
Maud Brandely-Talbot, Vice-President Medical Affairs, Chief Medical Officer (CMO);
Jean-Philippe Del, Vice-President, Chief Financial Officer (CFO);
Thibaut du Fayet, Vice-President Corporate Development;
John Felitti, Vice-President, General Counsel, Corporate Secretary;
Gaëlle Stadtler, Vice-President, Human Resources Director.
References
External links
Mérieux family
Biotechnology companies established in 1979
Biotechnology companies of France
Companies listed on Euronext Paris
Life sciences industry
Pharmaceutical companies established in 1979
French companies established in 1979
Pharmaceutical companies of France | Transgene (company) | Biology | 834 |
16,948,367 | https://en.wikipedia.org/wiki/NFPA%2072 | The NFPA 72 (National Fire Alarm and Signaling Code) is a standard published by the National Fire Protection Association every 3 years for installation of fire alarm systems and emergency communication systems in the United States.
Purpose
The NFPA 72 "covers the application, installation, location, performance, inspection, testing, and maintenance of fire alarm systems, supervising station alarm systems, public emergency alarm reporting systems, fire warning equipment and emergency communications systems (ECS), and their components." Federal, state, and local municipalities across the United States have adopted the NFPA 72 as a standard in the enforcement of fire code regulation. Municipalities often adopt revisions of the code after years of review and amendments, making many local fire codes specific to their governing authorities.
Structure
The NFPA 72 2022 (Current) is sectioned as follows:
Chapter 1 Administration
Chapter 2 Referenced Publications
Chapter 3 Definitions
Chapter 4 Reserved
Chapter 5 Reserved
Chapter 6 Reserved
Chapter 7 Document
Chapter 8 Reserved
Chapter 9 Reserved
Chapter 10 Fundamentals
Chapter 11 Reserved
Chapter 12 Circuits and Pathways
Chapter 13 Reserved
Chapter 14 Inspection, Testing, and Maintenance
Chapter 15 Reserved
Chapter 16 Reserved
Chapter 17 Initiating Devices
Chapter 18 Notification Appliances
Chapter 19 Reserved
Chapter 20 Reserved
Chapter 21 Emergency Control Function Interfaces
Chapter 22 Reserved
Chapter 23 Protected Premises Alarm and Signaling Systems
Chapter 24 Emergency Communications Systems (ECS)
Chapter 25 Reserved
Chapter 26 Supervising Station Alarm Systems
Chapter 27 Public Emergency Alarm Reporting Systems
Chapter 28 Reserved
Chapter 29 Single- and Multiple-Station Alarms and Household Signaling Systems
Annex A Explanatory Material
Annex B Engineering Guide for Automatic Fire Detector Spacing
Annex C System Performance and Design Guide
Annex D Speech Intelligibility
Annex E Sample Ordinance Adopting NFPA 72
Annex F Wiring Diagrams and Guide for Testing Fire Alarm Circuits
Annex G Guidelines for Emergency Communication Strategies for Buildings and Campuses
Annex H Carbon Monoxide
Annex I Informational References
Index
The previous version of NFPA 72 (2016) was sectioned as follows:
1. Administration
2. References and Publications
3. Definitions
4. Reserved
5. Reserved
6. Reserved
7. Documentation
8. Reserved
9. Reserved
10. Fundamentals
11. Reserved
12. Circuits and Pathways
13. Reserved
14. Inspection, Testing, and Maintenance
15. Reserved
16. Reserved
17. Initiating Devices
18. Notification Appliances
19. Reserved
20. Reserved
21. Emergency Control Interfaces
22. Reserved
23. Protected Premises Fire Alarm Systems
24. Emergency Communications Systems (ECS)
25. Reserved
26. Supervision Station Alarm Systems
27. Public Emergency Alarm Reporting Systems
28. Reserved
29. Single and Multiple-Station Alarms and Household Fire Alarm Systems
Annex A
Annex B
Annex C
Annex D
Annex E
Annex F
Annex G Informational References
Index
References
Firefighting in the United States
Safety codes
Safety organizations
Electrical standards
NFPA Standards | NFPA 72 | Physics | 552 |
58,540,794 | https://en.wikipedia.org/wiki/Aspergillus%20pulvinus | Aspergillus pulvinus is a species of fungus in the genus Aspergillus. It is from the Cremei section. The species was first described in 1965.
Growth and morphology
A. pulvinus has been cultivated on both Czapek yeast extract agar (CYA) plates and Malt Extract Agar Oxoid® (MEAOX) plates. The growth morphology of the colonies can be seen in the pictures below.
References
pulvinus
Fungi described in 1965
Fungus species | Aspergillus pulvinus | Biology | 108 |
1,703,850 | https://en.wikipedia.org/wiki/List%20of%20antiviral%20drugs | Antiviral drugs are different from antibiotics. Flu antiviral drugs are different from antiviral drugs used to treat other infectious diseases such as COVID-19. Antiviral drugs prescribed to treat COVID-19 are not approved or authorized to treat flu.
References
Antiviral
Antiviral drugs | List of antiviral drugs | Chemistry,Biology | 64 |
45,655,564 | https://en.wikipedia.org/wiki/Gepotidacin | Gepotidacin (INN) is an experimental antibiotic that acts as a topoisomerase type II inhibitor. It is being studied for the treatment of uncomplicated urinary tract infection (acute cystitis) and infection with Neisseria gonorrhoeae (gonorrhea), including multidrug resistant strains.
In October 2024, gepotidacin was granted priority review by the US Food and Drug Administration (FDA) for the treatment of uncomplicated urinary tract infections.
References
Antibiotics
Experimental drugs | Gepotidacin | Biology | 115 |
23,758,509 | https://en.wikipedia.org/wiki/List%20of%20solar%20eclipses%20in%20the%2022nd%20century | During the 22nd century, there will be 235 solar eclipses of which 79 will be partial, 87 will be annular, 65 will be total and 4 will be hybrids between total and annular eclipses. Of these, five annular eclipses will be non-central, in the sense that the very center (axis) of the Moon's shadow will miss the Earth (for more information see gamma). In the 22nd century, the greatest number of eclipses in one year is four, in 11 different years: 2112, 2134, 2141, 2152, 2159, 2170, 2177, 2181, 2188, 2195, and 2199. The predictions given here are by Fred Espenak of NASA's Goddard Space Flight Center.
The longest measured duration in which the Moon completely covered the Sun, known as totality, will be during the solar eclipse of July 16, 2186. This total solar eclipse will have a maximum duration of 7 minutes and 29.22 seconds. This will be the longest total solar eclipse between 4000 BCE and at least CE 6000 (10,000 years). The longest possible duration of a total solar eclipse is 7 minutes and 32 seconds. The longest annular solar eclipse of the 22nd century will take place on January 10, 2168, with a duration of 10 minutes and 55 seconds. The maximum possible duration is 12 minutes and 29 seconds.
The table contains the date and time of the greatest eclipse (in dynamical time), which in this case is the time when the axis of the Moon's shadow cone passes closest to the centre of Earth; this is in (Ephemeris Time). The number of the saros series that the eclipse belongs to is given, followed by the type of the eclipse (either total, annular, partial or hybrid), the gamma of the eclipse (how centrally the shadow of the Moon strikes the Earth), and the magnitude of the eclipse (the fraction of the Sun's diameter obscured by the Moon). For total and annular eclipses, the duration of the eclipse is given, as well as the location of the greatest eclipse (the point of maximum eclipse) and the path width of the total or annular eclipse. The geographical areas from which the eclipse can be seen are listed along with a chart illustrating each eclipse's respective path.
Longest and shortest
Eclipses
References
Bibliography
solar eclipses
+22
+22 | List of solar eclipses in the 22nd century | Astronomy | 499 |
12,144,738 | https://en.wikipedia.org/wiki/Germ%20cell%20nuclear%20factor | The germ cell nuclear factor (GCNF), also known as RTR (retinoid receptor-related testis-associated receptor) or NR6A1 (nuclear receptor subfamily 6, group A, member 1), is a protein that in humans is encoded by the NR6A1 gene. GCNF is a member of the nuclear receptor family of intracellular transcription factors .
In adults, GCNH is expressed mainly in the germ cells of gonads and is involved in the regulation of embryogenesis and germ cell differentiation.
Its expression pattern suggests that it may be involved in neurogenesis and germ cell development. The protein can homodimerize and bind DNA, but in vivo targets have not been identified. The gene expresses three alternatively spliced transcript variants.
In cells undergoing homologous recombination during meiosis, DNA intermediates are processed as an essential step in the exchange of information between parental homologous chromosomes. In eukaryotes the RTR complex, which consists of a type IA topoisomerase, a RecQ helicase and the structural protein RMI1, is employed in processing DNA recombination intermediates.
References
Further reading
External links
Intracellular receptors
Transcription factors | Germ cell nuclear factor | Chemistry,Biology | 258 |
50,247,503 | https://en.wikipedia.org/wiki/Sponge%20ground | Sponge grounds, also known as sponge aggregations, are intertidal to deep-sea habitats formed by large accumulations of sponges (glass sponges and/or demosponges), often dominated by a few massive species. Sponge grounds were already reported more than 150 years ago, but the habitat was first fully recognized, studied and described in detail around the Faroe Islands during the inter-Nordic BIOFAR 1 programme 1987–90. These were called Ostur (meaning "cheese" and referring to the appearance of the sponges) by the local fishermen and this name has to some extent entered the scientific literature. Sponge grounds were later found elsewhere in the Northeast Atlantic and in the Northwest Atlantic, as well as near Antarctica. They are now known from many other places worldwide and recognized as key marine habitats.
Sponge grounds are important habitats supporting diverse ecosystems. During a study of outer shelf and upper slope sponge grounds at the Faroe Islands, 242 invertebrate species were found in the vicinity and 115 were associated with the sponges. In general, fish fauna associated with sponge grounds are poorly known, but include rockfish and gadiforms. Sponge grounds are threatened, especially by bottom trawling and other fishing gear, dredging, oil and gas exploration and undersea cables, but potentially also by deep sea mining, carbon dioxide sequestration, pollution and climate change.
Prehistoric sponge grounds
By studying spicules in sediments cores taken from sponge grounds on the slopes of the Flemish Cap and Grand Bank (off Newfoundland, Canada), scientists managed to detect the presence of sponges in the past. The oldest record for Geodiidae sponges in this region was found in a long core collected in the slope of the Grand Bank, where typical sterraster spicules were found in the top of a submarine landslide deposit older than 25 000 BP. Continuous presence of sponges was recorded on the southeastern region of the Flemish Cap as far as 130 000 BP. It seems the distribution range of the Geodiidae in this area significantly expended after the deglaciation.
References
Sponge biology
Ecosystems
Oceanographical terminology | Sponge ground | Biology | 430 |
18,013,952 | https://en.wikipedia.org/wiki/LN%20Andromedae | LN Andromedae (LN And), also known as HD 217811, HR 8768, is a formerly suspected variable star in the constellation Andromeda. Located approximately away from Earth, it shines with an apparent visual magnitude 6.41, thus it can be seen by the naked eye under very favourable conditions. Its spectral classification is B2V, meaning that it is a hot main sequence star, emitting light approximately with a blackbody spectrum at an effective temperature of 18,090 K.
Companion
In the Washington Double Star Catalog LN And has a faint optical companion star with an apparent magnitude of 9.88, from LN And. The separation has increased from when it was discovered as a double in 1828. The two stars share the same Hipparcos identifier HIP 113802, and have very similar parallaxes and proper motions.
Variability
In 1979, the blue magnitude of LN And was reported to vary by about 0.025 every 28 minutes. Such variability was not known for any class of variable, but the position in the Hertzsprung–Russell diagram at the main sequence (low luminosity) end of the same instability strip as the β Cephei stars would make high-overtone radial pulsations the likely cause. LN And was added to the General Catalogue of Variable Stars as LN Andromedae, but follow-up studies failed to find the same rapid variations, or any significant variations in brightness and it is now listed as probably constant.
Analysis of Hipparcos photometry shows variability of about 0.0059 magnitudes with a main period of . The statistical threshold for these variations is at a level which is only met by 0.01% of stars.
References
Andromeda (constellation)
217811
Andromedae, LN
B-type main-sequence stars
8768
113802
Durchmusterung objects
Slowly pulsating B-type stars
Suspected variables
A-type main-sequence stars | LN Andromedae | Astronomy | 415 |
4,094,719 | https://en.wikipedia.org/wiki/TEK%20search%20engine | TEK is an email-based search engine developed by the TEK project at the Massachusetts Institute of Technology. The search engine enables users to search the Web using only email. It is intended to be used by people with low internet connectivity (for example, high-priced internet connection and low bandwidth connection in developing countries).
TEK stands for "Time Equals Knowledge"; the search engine compensates the searching availability to the time needed for searching. To perform a web search, a user sends a query via email to a server (which is located at MIT). The server then performs the search using existing search engines, downloads actual pages, and emails a subset of those pages back to the user.
References
Levison L, Thies B, Amarasinghe S. The TEK Search Engine. Development by design workshop, MIT, Boston, MA. July 2001. http://tek.sourceforge.net/papers/tek-dyd01.pdf
External links
TEK Project
Internet search engines | TEK search engine | Technology | 208 |
17,455,275 | https://en.wikipedia.org/wiki/Display%20aspect%20ratio | The display aspect ratio (DAR) is the aspect ratio of a display device and so the proportional relationship between the physical width and the height of the display. It is expressed as two numbers separated by a colon (x:y), where x corresponds to the width and y to the height. Common aspect ratios for displays, past and present, include 5:4, 4:3, 16:10, and 16:9.
To distinguish:
The display aspect ratio (DAR) is calculated from the physical width and height of a display, measured each in inch or cm (Display size).
The pixel aspect ratio (PAR) is calculated from the width and height of one pixel.
The storage aspect ratio (SAR) is calculated from the numbers of pixels in width and height stated in the display resolution.
Because the units cancel out, all aspect ratios are unitless.
Diagonal and area
The size of a television set or computer monitor is given as the diagonal measurement of its display area, usually in inches. Wider aspect ratios result in smaller overall area, given the same diagonal.
TVs
Most televisions were built with an aspect ratio of 4:3 until the late 2000s, when widescreen TVs with 16:9 displays became the standard. This aspect ratio was chosen as the geometric mean between 4:3 and 2.35:1, an average of the various aspect ratios used in film. While 16:9 is well-suited for modern HDTV broadcasts, older 4:3 video has to be either padded with bars on the left and right side (pillarboxed), cropped or stretched, while movies shot with wider aspect ratios are usually letterboxed, with black bars at the top and bottom.
Since the turn of the 21st century, many music videos began shooting on widescreen aspect ratio.
Computer displays
As of 2016, most computer monitors use widescreen displays with an aspect ratio of 16:9, although some portable PCs use narrower aspect ratios like 3:2 and 16:10 while some high-end desktop monitors have adopted ultrawide displays.
The following table summarises the different aspect ratios that have been used in computer displays:
† The aspect ratio is approximate.
History
4:3, 5:4 and 16:10
Until about 2003, most computer monitors used an aspect ratio of 4:3, and in some cases 5:4. For cathode ray tubes (CRTs) 4:3 was most common even in resolutions where this meant the pixels would not be square (e.g. 320×200 or 1280×1024 on a 4:3 display). Between 2003 and 2006, monitors with 16:10 aspect ratio became commonly available, first in laptops and later also in standalone computer monitors. Reasons for this transition was productive uses for such monitors, i.e. besides widescreen movie viewing and computer game play, are the word processor display of two standard A4 or letter pages side by side, as well as CAD displays of large-size drawings and CAD application menus at the same time. 16:10 became the most common sold aspect ratio for widescreen computer monitors until 2008.
16:9
In 2008, the computer industry started to move from 4:3 and 16:10 to 16:9 as the standard aspect ratio for monitors and laptops. A 2008 report by DisplaySearch cited a number of reasons for this shift, including the ability for PC and monitor manufacturers to expand their product ranges by offering products with wider screens and higher resolutions, helping consumers to more easily adopt such products and "stimulating the growth of the notebook PC and LCD monitor market".
By 2010, virtually all computer monitor and laptop manufacturers had also moved to the 16:9 aspect ratio, and the availability of 16:10 aspect ratio in mass market had become very limited. In 2011, non-widescreen displays with 4:3 aspect ratios still were being manufactured, but in small quantities. The reasons for this according to Bennie Budler, product manager of IT products at Samsung South Africa was that the "demand for the old 'Square monitors' has decreased rapidly over the last couple of years". He also predicted that "by the end of 2011, production on all 4:3 or similar panels will be halted due to a lack of demand."
In 2012, 1920×1080 was the most commonly used resolution among Steam users. At the same time, the most common resolution globally was 1366×768, overtaking the previous leader 1024×768. In 2021, the 2K resolution of 1920×1080 was used by two thirds of the Steam users for the primary display with 1366×768 and 2560×1440 both at about eight percent taking the majority of the remaining resolutions.
3:2
3:2 displays first appeared in laptop computers in 2001 with the PowerBook G4 line, but did not enter the mainstream until the 2010s with the Chromebook Pixel and 2-in-1 PCs like Microsoft's Surface line. As of 2018, a number of manufacturers are either producing or planning to produce portable PCs with 3:2 displays.
21:9
Since 2014, a number of high-end desktop monitors have been released that use ultrawide displays with aspect ratios that roughly match the various anamorphic formats used in film, but are commonly marketed as 21:9. Resolutions for such displays include 2560×1080 (64:27), 3440×1440 (43:18) and 3840×1600 (12:5).
32:9
In 2017, Samsung released a curved gaming display with an aspect ratio of 32:9 and resolution of 3840×1080.
256:135
Since 2011, several monitors complying with the Digital Cinema Initiatives 4K standard have been produced; this standard specifies a resolution of 4096×2160, giving an aspect ratio of ≈1.896:1.
1:1
A 1:1 aspect ratio results in a square display. One of the available monitors for desktop use of this format is Eizo EV2730Q (27", 1920 × 1920 Pixels, from 2015), however such monitors are also often found in air traffic control displays (connected using standard computer cabling, like DVI or DisplayPort) and on aircraft as part of avionic equipment (often connected directly using LVDS, SPI interfaces or other specialized means). This 1920×1920 display can also be used as the centerpiece of a three-monitor array with one WUXGA set in vertical position on each side, resulting in 4320×1920 (a ratio of 9:4) - and no distortion with the Eizo 27" 1:1 if the side displays are 22".
Suitability for software and content
Games
From 2005 to 2013, most video games were mainly made for the 16:9 aspect ratio and 16:9 computer displays therefore offer the best compatibility. 16:9 video games are letterboxed on a 16:10 or 4:3 display or have reduced field of view.
As of 2013, many games are adopting support for 21:9 ultrawide resolutions, which can give a gameplay advantage due to increased field of view, although this is not always the case.
4:3 monitors have the best compatibility with older games released prior to 2005 when that aspect ratio was the mainstream standard for computer displays.
Video
As of 2017, the most common aspect ratio for TV broadcasts is 16:9, whereas movies are generally made in the wider 21:9 aspect ratio. Most modern TVs are 16:9, which causes letterboxing when viewing 21:9 content, and pillarboxing when viewing 4:3 content such as older films or TV broadcasts, unless the content is cropped or stretched to fill the entire display.
Productivity applications
For viewing documents in A4 paper size (which has a 1.41:1 aspect ratio), whether in portrait mode or two side-by-side in landscape mode, 4:3, 2:3 or 16:10 fit best. For photographs in the standard 135 film and print size (with a 3:2 aspect ratio), 2:3 or 16:10 fit best; for photographs taken with older consumer-level digital cameras, 4:3 fits perfectly.
Smartphones
Until 2010, smartphones used different aspect ratios, including 3:2 and 5:3. From 2010 to 2017 most smartphone manufacturers switched to using 16:9 widescreen displays, driven at least partly by the growing popularity of HD video using the same aspect ratio.
Since 2017, a number of smartphones have been released using 18:9 or even wider aspect ratios (such as 19.5:9 or 20:9); such displays are expected to appear on increasingly more phones. Reasons for this trend include the ability for manufacturers to use a nominally larger display without increasing the width of the phone, being able to accommodate the on-screen navigation buttons without reducing usable app area, more area available for split-screen apps in portrait orientation, as well as the 18:9 ratio being well-suited for VR applications and the proposed Univisium film format. On the other hand, the disadvantages of taller 18:9 aspect ratio phones with some phones even going up to 20:9, 21:9, or even 22:9 in the case of Samsung's Z Flip series, is reduced one-handed reachability, being less convenient to carry around in the pocket as they stick out and reduced overall screen surface area.
See also
14:9 aspect ratio
Computer monitor
Display resolution
Field of view in video games
Display resolution standards
Ultrawide formats
References
Display technology
Engineering ratios | Display aspect ratio | Mathematics,Engineering | 1,965 |
22,944,638 | https://en.wikipedia.org/wiki/Comparison%20of%20EDA%20software | This page is a comparison of electronic design automation (EDA) software which is used today to design the near totality of electronic devices. Modern electronic devices are too complex to be designed without the help of a computer. Electronic devices may consist of integrated circuits (ICs), printed circuit boards (PCBs), field-programmable gate arrays (FPGAs) or a combination of them. Integrated circuits may consist of a combination of digital and analog circuits. These circuits can contain a combination of transistors, resistors, capacitors or specialized components such as analog neural networks, antennas or fuses.
The design of each of these electronic devices generally proceeds from a high- to a low-level of abstraction. For FPGAs the low-level description consists of a binary file to be flashed into the gate array, while for an integrated circuit the low-level description consists of a layout file which describes the masks to be used for lithography inside a foundry.
Each design step requires specialized tools, and many of these tools can be used for designing multiple types of electronic circuits. For example, a program for high-level digital synthesis can usually be used both for IC digital design as well as for programming an FPGA. Similarly, a tool for schematic-capture and analog simulation can generally be used both for IC analog design and for PCB design.
In the case of integrated circuits (ICs) for example, a single chip may contain today more than 20 billion transistors (which is more than two transistors for every human on Earth) and, as a general rule, every single transistor in a chip must work as intended. Since a single VLSI mask set can cost up to 10-100 millions, trial and error approaches are not economically viable. To minimize the risk of any design mistakes, the design flow is heavily automatized. EDA software assists the designer in every step of the design process and every design step is accompanied by heavy test phases. Errors may be present in the high-level code already, such as for the Pentium FDIV floating-point unit bug, or it can be inserted all the way down to physical synthesis, such as a missing wire, or a timing violation.
Comparison of proprietary EDA software
Mainstream EDA software bundles for ICs design
The world of electronic design automation (EDA) software for integrated circuit (IC) design is dominated by the three vendors Synopsys, Cadence Design Systems and Siemens EDA (Formerly Mentor Graphics, acquired in 2017 by Siemens) which have a revenue respectively of 4,2 billion US$, 3 billion US$ and 1,3 billion US$.
These vendors offer software bundles which allow to cover the full spectrum of IC design, from HDL synthesis to physical synthesis and verification.
The development of EDA software is tightly connected with the development of technology nodes. The properties of a specific semiconductor foundry, such as the transistor models, the physical characteristics and the design rules, are usually encoded in file formats which are proprietary to one or more EDA vendors. This set of files constitutes the process design kit (PDK) and it is usually developed as a joint effort between the foundry and an EDA vendor. Foundries therefore usually release PDKs which are compatible only for one specific EDA bundle. The information contained inside PDKs is usually considered confidential. PDKs are therefore usually protected by non disclosure agreements (NDAs) and may be shipped in an incomplete or in an encrypted form to the designers.
Proprietary software for electrical simulation (analog/mixed-signal/electromagnetic)
Of these, LTSpice and Micro-cap are free proprietary applications based on SPICE. Micro-Cap was released as freeware in July 2019, when its parent company Spectrum Software closed down while LTSpice has been free for a long time.
Comparison of proprietary software for PCB design
Comparison of free & open source software EDA tools
Free & open source software EDA bundles for IC design
Free and open-source (FOSS) EDA software bundles are currently under fast development mainly thanks to the DARPA and Google's openROAD project. The OpenROAD project offers a complete stack of tools from high-level synthesis down to layout generation
The flow includes Yosys for logic synthesis, OpenLane for physical synthesis and targets the SkyWater 130nm PDK. The flow is currently utilized to submit design for free fabrication at Google.
Free & open source software for high-level synthesis
High-level synthesis software can generally be used for the design of both application-specific integrated circuits (ASICs) and field-programmable gate arrays (FPGAs). Most high-level synthesis software is used to edit and verify code written in one of the mainstream hardware description languages (HDL) like VHDL or Verilog. Other tools instead operate at a higher level of abstraction and allow to synthesize HDL code starting from languages like Chisel or SpinalHDL. The higher abstraction of such languages enables formal verification of HDL code.
List by developer
Free software for IC physical synthesis and layout
This list does not include schematic editors or simulators since these can generally be used both for Integrated Circuits (ICs) and for Printed Circuit Board (PCB) as long as device models are available.
Free software for schematic editing and analog/mixed-signal simulation
Free software for PCB design
See also
Electronic design automation (EDA)
List of EDA companies
List of computer-aided engineering software
List of finite element software packages
List of free electronics circuit simulators
List of numerical analysis software
List of software engineering topics
Power engineering software
Schematic editor
SPICE, a general purpose analog circuit simulator.
TopoR
References
Software comparisons | Comparison of EDA software | Technology | 1,174 |
51,693,407 | https://en.wikipedia.org/wiki/Hybrid%20navigation | Hybrid navigation is the simultaneous use of more than one navigation system for location data determination, needed for navigation. By using multiple systems at once, the accuracy as a whole is improved. It also allows for a more reliable navigation system, as if one system fails, the other can kick in and provide accurate navigation for the user. Especially for self-driving cars, the exact and continuous knowledge of the navigating object's location is essential.
Function
GPS and other satellite based systems (GLONASS, GALILEO, BEIDOU, QZSS) provide a way to learn one's location, but these methods require free field conditions in order to receive the radio signal. Various satellite systems are subject to switching-off or reduction of data precision by the company or government that runs them. They are also prone to intentional or unintentional disturbances. Even passing through a tunnel or a garage interrupts the data flow. In situations where the signal cannot be received reliably, alternate sources of location data are needed. Combining GPS with other methods can avoid these limitations, but each method has its own specific limitations. A hybrid system provides fault tolerance for each underlying method and improves the overall precision of the result.
The hybrid system needs to decide how to choose among the different methods at any given time. One solution is a triple configuration, allowing 'result voting' for data collecting systems.
Alternate systems that supply navigational data include:
Beacons providing radio- or infrared based signals.
Inertial navigation systems. This system determines location by summing the movement vectors from start of the trip or some other waypoint whose location is well-defined.
Incremental sensors. This system uses vehicle speed data supplied by a Fleet Management System.
Differential GPS. This system uses terrestrial radio transmitters with well-defined locations that broadcast information about how accurate the GPS signals are at identifying the locations of these transmitters.
See also
Automotive navigation system
Hybrid positioning system
Navigation Data Standard
Sensor fusion
References
External links
Homepage of 'Deutschen Gesellschaft für Ortung und Navigation (DGON)'
Wildau Video
Mobile technology
Communication
Navigational equipment | Hybrid navigation | Technology | 424 |
31,314,683 | https://en.wikipedia.org/wiki/Granville%20number | In mathematics, specifically number theory, Granville numbers, also known as -perfect numbers, are an extension of the perfect numbers.
The Granville set
In 1996, Andrew Granville proposed the following construction of a set :
Let , and for any integer larger than 1, let if
A Granville number is an element of for which equality holds, that is, is a Granville number if it is equal to the sum of its proper divisors that are also in . Granville numbers are also called -perfect numbers.
General properties
The elements of can be -deficient, -perfect, or -abundant. In particular, 2-perfect numbers are a proper subset of .
S-deficient numbers
Numbers that fulfill the strict form of the inequality in the above definition are known as -deficient numbers. That is, the -deficient numbers are the natural numbers for which the sum of their divisors in is strictly less than themselves:
S-perfect numbers
Numbers that fulfill equality in the above definition are known as -perfect numbers. That is, the -perfect numbers are the natural numbers that are equal the sum of their divisors in . The first few -perfect numbers are:
6, 24, 28, 96, 126, 224, 384, 496, 1536, 1792, 6144, 8128, 14336, ...
Every perfect number is also -perfect. However, there are numbers such as 24 which are -perfect but not perfect. The only known -perfect number with three distinct prime factors is 126 = 2 · 32 · 7.
Every number of form 2^(n - 1) * (2^n - 1) * (2^n)^m where m >= 0, where 2^n - 1 is Prime, are Granville Numbers. So, there are infinitely many Granville Numbers and the infinite family has 2 prime factors- 2 and a Mersenne Prime. Others include 126, 5540590, 9078520, 22528935, 56918394 and 246650552 having 3, 5, 5, 5, 5 and 5 prime factors.
S-abundant numbers
Numbers that violate the inequality in the above definition are known as -abundant numbers. That is, the -abundant numbers are the natural numbers for which the sum of their divisors in is strictly greater than themselves:
They belong to the complement of . The first few -abundant numbers are:
12, 18, 20, 30, 42, 48, 56, 66, 70, 72, 78, 80, 84, 88, 90, 102, 104, ...
Examples
Every deficient number and every perfect number is in because the restriction of the divisors sum to members of either decreases the divisors sum or leaves it unchanged. The first natural number that is not in is the smallest abundant number, which is 12. The next two abundant numbers, 18 and 20, are also not in . However, the fourth abundant number, 24, is in because the sum of its proper divisors in is:
1 + 2 + 3 + 4 + 6 + 8 = 24
In other words, 24 is abundant but not -abundant because 12 is not in . In fact, 24 is -perfect - it is the smallest number that is -perfect but not perfect.
The smallest odd abundant number that is in is 2835, and the smallest pair of consecutive numbers that are not in are 5984 and 5985.
References
Number theory | Granville number | Mathematics | 706 |
58,106,740 | https://en.wikipedia.org/wiki/C17%20%28C%20standard%20revision%29 | C17, formally ISO/IEC 9899:2018, is an open standard for the C programming language, prepared in 2017 and published in July 2018. It replaced C11 (standard ISO/IEC 9899:2011), and is superseded by C23 (ISO/IEC 9899:2024) since October 2024. Since it was under development in 2017, and officially published in 2018, C17 is sometimes referred to as C18.
Changes from C11
C17 fixes numerous minor defects in C11 without introducing new language features.
The __STDC_VERSION__ macro is increased to the value 201710L.
For a detailed list of changes from the previous standard, see Clarification Request Summary for C11.
Compiler support
List of compilers supporting C17:
GCC 8.1.0
LLVM Clang 7.0.0
IAR EWARM v8.40.1
Microsoft Visual C++ VS 2019 (16.8)
Pelles C 9.00
See also
C++23, C++20, C++17, C++14, C++11, C++03, C++98, versions of the C++ programming language standard
Compatibility of C and C++
References
Further reading
N2176 (final draft of C17 standard); WG14; 2017.
ISO/IEC 9899:2018 (official C17 standard); ISO; 2018.
External links
C Language Working Group 14 (WG14) Documents
C (programming language)
Programming language standards
IEC standards
ISO standards | C17 (C standard revision) | Technology | 330 |
49,168,382 | https://en.wikipedia.org/wiki/EsyN | esyN (Easy Networks) is a bioinformatics web-tool for visualizing, building and analysing molecular interaction networks. esyN is based on cytoscape.js and its aim is to make it easy for everybody to perform network analysis.
esyN is connected with a number of databases - specifically: pombase, flybase, and most InterMine data warehouses, DrugBank, and BioGRID from which its possible to download the protein protein or genetic interactions for any protein or gene in a number of different organisms.
Networks published in esyN can be easily published in other websites using the <iframe> methodology.
Usage
As of January 2016 esyN is being viewed by 1500 unique users a day (about 16000 a month) according to Google Analytics.
The embedding capabilities of esyN are used by a number of databases to display their interaction data:
FlyBase
FlyMine
HumanMine
PomBase
See also
Computational genomics
Metabolic network modelling
Protein–protein interaction prediction
References
External links
Bioinformatics software
Metabolomic databases
Proteomics
Science and technology in Cambridgeshire
South Cambridgeshire District | EsyN | Biology | 228 |
46,451,987 | https://en.wikipedia.org/wiki/Ramaria%20aurea | Ramaria aurea is a coral mushroom in the family Gomphaceae. It is found in North America and Europe. It is similar to R. flava; both species are edible.
References
External links
Gomphaceae
Edible fungi
Fungi described in 1888
Fungi of North America
Fungus species | Ramaria aurea | Biology | 60 |
26,630,167 | https://en.wikipedia.org/wiki/Bethe%E2%80%93Slater%20curve | The Bethe–Slater curve is a heuristic explanation for why certain metals are ferromagnetic and others are antiferromagnetic. It assumes a Heisenberg model of magnetism, and explains the differences in exchange energy of transition metals as due to the ratio of the interatomic distance a to the radius r of the 3d electron shell. When the magnetically important 3d electrons of adjacent atoms are relatively close to each other, the exchange interaction, , is negative, but when they are further away, the exchange interaction becomes positive, before slowly dropping off.
The idea of relating exchange energy to inter-atomic distance was first proposed by John C. Slater in 1930, and illustrated as a curve on a graph in a review by Sommerfeld and Bethe in 1933.
For a pair of atoms, the exchange interaction wij (responsible for the energy E) is calculated as:
where: = exchange integral; S = electron spins; i and j = indices of the two atoms.
The Slater curve does produce realistic results, predicting Iron, Cobalt and Nickel to be the elements with ferromagnetic ordering. The curve is of practical use as a simple way of estimating based on the average atomic separation. However, more recent evaluations with realistic calculations of the exchange interactions show significantly more complex physics when treating the interactions of different atomic orbitals in an atom separately, rather than as a single unit.
External links
Open Quantum Materials Database
References
Magnetic exchange interactions
Ferromagnetism | Bethe–Slater curve | Chemistry,Materials_science | 305 |
14,517,823 | https://en.wikipedia.org/wiki/Melanin-concentrating%20hormone%20receptor%202 | Melanin-concentrating hormone receptor 2 (MCH2) also known as G-protein coupled receptor 145 (GPR145) is a protein that in humans is encoded by the MCHR2 gene.
MCH2 is also found in dogs, ferrets, and some other primates and carnivores, but is not found in mice or rats. This has delayed research into the receptor as a therapeutic target, due to most early pharmaceutical research usually being conducted in small mammals such as mice, rats or rabbits which lack the MCH2 gene and its receptor product.
Clinical significance
Treatment of human cells expressing MCHR2 with MCH resulted in upregulation of IDH3A, PCK1 and PFKFB4 and the downregulation of INSIG2 and ACOT8.
See also
Melanin-concentrating hormone receptor
References
External links
Further reading
G protein-coupled receptors
Human proteins | Melanin-concentrating hormone receptor 2 | Chemistry | 190 |
28,157,642 | https://en.wikipedia.org/wiki/List%20of%20aperiodic%20sets%20of%20tiles | In geometry, a tiling is a partition of the plane (or any other geometric setting) into closed sets (called tiles), without gaps or overlaps (other than the boundaries of the tiles). A tiling is considered periodic if there exist translations in two independent directions which map the tiling onto itself. Such a tiling is composed of a single fundamental unit or primitive cell which repeats endlessly and regularly in two independent directions. An example of such a tiling is shown in the adjacent diagram (see the image description for more information). A tiling that cannot be constructed from a single primitive cell is called nonperiodic. If a given set of tiles allows only nonperiodic tilings, then this set of tiles is called aperiodic. The tilings obtained from an aperiodic set of tiles are often called aperiodic tilings, though strictly speaking it is the tiles themselves that are aperiodic. (The tiling itself is said to be "nonperiodic".)
The first table explains the abbreviations used in the second table. The second table contains all known aperiodic sets of tiles and gives some additional basic information about each set. This list of tiles is still incomplete.
Explanations
List
References
External links
Stephens P. W., Goldman A. I. The Structure of Quasicrystals
Levine D., Steinhardt P. J. Quasicrystals I Definition and structure
Tilings Encyclopedia
Mathematics-related lists | List of aperiodic sets of tiles | Physics | 302 |
37,543,707 | https://en.wikipedia.org/wiki/Cantharellus%20flavus | Cantharellus flavus, also called the American golden chanterelle, Eastern yellow chanterelle or Midwestern yellow chanterelle, is a species of fungus in the genus Cantharellus. Found in North America, it is an edible mushroom.
Taxonomy
Cantharellus flavus was described in 2013 by Matthew Foltz and Tom Volk.
Initially, C. flavus was classified along with similar species under the species name Cantharellus cibarius. Since the description of this species in 2013, its validity as a distinct species has been questioned, due to the heterogeneity of its morphology and habitat, which overlaps with the distinguishing characteristics of other species, and only minor molecular differences. Therefore, it has been suggested that C. flavus is part of the species complex of Cantharellus tenuithrix.
Its epithet flavus comes from the Latin word for "yellow", referring to this species' yellow spore print, stipe, false gills and cap.
Description
The cap is convex when young, flattening out, and arching with age, developing a depressed center. When mature, it can be broadly infundibuliform. It measures wide and has a wavy, tucked in margin. The hyphae of the cap have long terminal cells that measure 85–95 by 4.5–5.5 μm, a characteristic shared with C. phasmatis and C. tenuithrix. The flesh is yellow, though it pales towards the end of the stipe, and with age. The stipe measures 3–8 cm long and broad and may be tapered towards the base. Applying KOH to the flesh intensifies its color. Clamp connections are found throughout the fungal tissue.
The false gills are decurrent and forking, with rounded edges, and the spore print is yellow. The spores are oblong, transparent and smooth, measuring 8–11 x 4.5–6 μm. They do not change colour when mounted with iodine-based reagant (inamyloid). The basidia measure 75–80 by 7–9 μm and have 4–6 sterigma.
The taste is mild and slightly peppery and the odour is faintly of apricots.
Similar species
Cantharellus flavus can be distinguished from similar species by its yellow rather than white or orange false gills and stipe and yellow rather than pink spore print. It can be distinguished from C. lateritius by its well-developed false gills.
Distribution and habitat
The distribution of C. flavus is obscure due to its previous grouping with other species as C. cibarius. Its presence has been confirmed in Wisconsin, Tennessee, North Carolina and Texas, though it is presumed that it is common throughout eastern North America.
It prefers growing under oak, but can also grow under hardwoods, or a mixed stand of hardwoods and conifers. It is likely ectomycorrhizal with oak (Quercus spp.). It is found in well-drained soils, often on hillsides. It typically grows from July to September and can grow clustered, solitary, or scattered.
It was categorised as "least concern" by the IUCN red list in 2021.
Edibility
The species is edible.
References
External links
flavus
Fungi described in 2013
Fungi of North America
Edible fungi
Fungus species | Cantharellus flavus | Biology | 710 |
3,759,071 | https://en.wikipedia.org/wiki/Lability | Lability refers to something that is constantly undergoing change or is likely to undergo change. It is the opposite (antonym) of stability.
Biochemistry
In reference to biochemistry, this is an important concept as far as kinetics is concerned in metalloproteins. This can allow for the rapid synthesis and degradation of substrates in biological systems.
Biology
Cells
Labile cells refer to cells that constantly divide by entering and remaining in the cell cycle. These are contrasted with "stable cells" and "permanent cells".
An important example of this is in the epithelium of the cornea, where cells divide at the basal level and move upwards, and the topmost cells die and fall off.
Proteins
In medicine, the term "labile" means susceptible to alteration or destruction. For example, a heat-labile protein is one that can be changed or destroyed at high temperatures.
The opposite of labile in this context is "stable".
Soils
Compounds or materials that are easily transformed (often by biological activity) are termed labile. For example, labile phosphate is that fraction of soil phosphate that is readily transformed into soluble or plant-available phosphate. Labile organic matter is the soil organic matter that is easily decomposed by microorganisms.
Chemistry
The term is used to describe a transient chemical species. As a general example, if a molecule exists in a particular conformation for a short lifetime, before adopting a lower energy conformation (structural arrangement), the former molecular structure is said to have 'high lability' (such as C25, a 25-carbon fullerene spheroid). The term is sometimes also used in reference to reactivity – for example, a complex that quickly reaches equilibrium in solution is said to be labile (with respect to that solution). Another common example is the cis effect in organometallic chemistry, which is the labilization of CO ligands in the cis position of octahedral transition metal complexes.
See also
Chemical stability
Equilibrium chemistry
Dynamic equilibrium
Instability
Metastability
Reaction intermediate
Emotional lability
References
Chemical reactions | Lability | Chemistry,Biology | 424 |
99,537 | https://en.wikipedia.org/wiki/BowLingual | , or "Bow-Lingual" as the North American version is spelled, is a computer-based dog language-to-human language translation device developed by Japanese toy company Takara and first sold in Japan in 2002. Versions for South Korea and the United States were launched in 2003. The device was named by Time magazine as one of the "Best Inventions of 2002." The inventors of BowLingual, Keita Satoh, Matsumi Suzuki and Norio Kogure were awarded the 2002 Ig Nobel Prize for "promoting peace and harmony between the species."
The device is presented as a "translator" but has been called an "emotion analyzer". It is said to categorize dog barks into one of six standardized emotional categories. BowLingual also provides a phrase which is representative of that emotion. The product instructions state that these phrases "are for entertainment purposes only" and are not meant to be accurate translations of each bark.
Features
BowLingual has bow functions which include dog training tips, a "Bow Wow Diary," tips on understanding a dog's body language, a medical checklist and a home alone bark recording function. The device consists of a hand-held receiver that contains a LCD information screen and functions as the controller and a wireless microphone-transmitter which is attached to the dog's collar.
When a dog barks, the microphone records and transmits the sound to the hand-held unit for computer analysis by a database with thousands of dog barks pre-recorded into it. The unit then categorizes the bark into one of six distinct dog emotions (happy, sad, frustrated, on-guard, assertive, needy) and displays the corresponding emotion on the screen. After displaying the emotion, BowLingual then displays a phrase which has been categorized to fit within the range of each emotion.
Versions
Regional versionals of BowLingual have been released in Japan, South Korea, the US and Canada. The versions for South Korea, the US and Canada have different modifications in comparison to the Japanese version. In May 2003, at the request of the Japan Foreign Ministry, Takara provided Japanese Prime Minister Junichiro Koizumi with two prototypes of the English version of BowLingual several months before it had been released in North America. Koizumi then presented these to Russian President Vladimir Putin, for each of his dogs (Tosca, a standard Poodle, and Connie, a Labrador Retriever), at ceremonies celebrating the 300th anniversary of St. Petersburg.
Effectiveness
BowLingual uses customized voice-print analysis technology which has been adapted for dog barks. The accuracy of this product can be affected by varying conditions and situations. Sound interference can occur when the wireless collar-microphone picks up noises made by chain collars and collars with dog tags attached. As a result, the dog owner may believe that the device is malfunctioning and not registering the dog bark correctly.
In windy conditions, the microphone will sometimes interpret a gust of wind as a bark. Electrical equipment and certain radio signals may trigger false readouts. Due to improvements with the US and Canadian versions of the products, these problems are more common with the Japanese and South Korean versions.
One reviewer of the product, vet Sophia Yin stated "it's not very useful because the translations aren't trustworthy and most don't make sense."
Csaba Molnar and colleagues at Eotvos Lorand University, Budapest, Hungary proved by computer-based machine learning algorithms that there are consistent differences in the acoustics of dog barks according to the behavioural context and individuals.
Related products
In 2003 Takara launched a follow-up product for cats called Meowlingual (ミャウリンガル). It functioned similarly to BowLingual; however, it did not use the wireless microphone system. Instead, the microphone was contained in the main hand-held unit so that the user had to be close enough to, in effect, "interview" the cat. Without the wireless component, Meowlingual was considerably cheaper than BowLingual. Meowlingual was never launched in the U.S. or any other countries, so only Japanese language versions exist. The iPhone version of BowLingual similarly listens to the dog through the iPhone's microphone.
See also
Human-animal communication
External links
Time Magazine Best Inventions 2002, Bowlingual
BowLingual Web page (archived)
MeowLingual Web page (archived)
Bowlingual presented by Japan prime minister to Russian president
Critical review
References
Dog training and behavior
Machine translation
2000s toys
Human–animal communication | BowLingual | Technology | 927 |
360,374 | https://en.wikipedia.org/wiki/Young%20Scientist%20and%20Technology%20Exhibition | The BT Young Scientist and Technology Exhibition, commonly called the Young Scientist Exhibition, is an Irish annual school students' science competition that has been held in the Royal Dublin Society, Dublin, Ireland, every January since the competition was founded by Tom Burke and Tony Scott in 1965.
The competition
The purpose of the competition is to encourage interest in science in secondary schools. For the 51st year of the competition in 2016, there were over 2,000 entries, from 396 schools which was the highest number ever, 550 of which were selected for the Exhibition at the RDS.
Students apply to participate in the competition. Their science project entries are evaluated by judges and about one-third of applicants are accepted to participate in the public exhibition. Students are allocated exhibition stands in an exhibition hall where they set up their projects for viewing by the public. Competing projects are judged during the three days of the exhibition, and prizes are awarded.
Projects are awarded in five categories: biology, physics, social and behavioural sciences, health and wellbeing and technology. Health and wellbeing is the newest category, only being added in 2023 to celebrate the 60th anniversary and to lower admissions to social and behavioural sciences. Three levels of entry are accepted, junior, intermediate and senior. In each category three main prizes are awarded; other prizes include a display award, highly commended rosettes, and a cancer awareness award. The winners of the BT Young Scientist and Technology Exhibition advance to participate in prestigious international events such as the European Union Contest for Young Scientists.
John Monahan was the inaugural winner of the Young Scientist Exhibition in 1965; then a student of Newbridge College, his project was an explanation of the process of digestion in the human stomach. He went on to establish a NASDAQ-listed biotech company in California after attending University College Dublin.
Aer Lingus sponsored the competition for the first 33 years. 2021 marked the 21st year in which the Exhibition was sponsored by BT Ireland. It has produced at least one author, Sarah Flannery, and one billionaire, Patrick Collison. Many of the past winners have gone on to establish international companies in the technology they developed. One of the most notable was Baltimore Technologies.
Tom Burke, who co-founded the exhibition with physicist Tony Scott, died in March 2008. An award at the event (a bursary offered to senior participants) was named in his memory.
Due to the COVID-19 pandemic, the first ever virtual Young Scientist & Technology Exhibition was held in January 2021 with over 1,000 students representing more than 200 schools taking part.
Overall winners by year
Winners by age
The youngest winners are listed first.
See also
Education in the Republic of Ireland
Science Week Ireland
References
External links
Official archive
List of past winners
News article about 1999 project
News article about 1999 project
Slashdot Article on Adnan Osmani's Project
BT Group
1965 establishments in Ireland
Competitions in Ireland
Education in the Republic of Ireland
Recurring events established in 1965
Science competitions
Science and technology in the Republic of Ireland
Youth science
Youth in the Republic of Ireland
Science events in Ireland | Young Scientist and Technology Exhibition | Technology | 623 |
47,581,481 | https://en.wikipedia.org/wiki/Frailty%20index | The frailty index (FI) can be used to measure the health status of older individuals; it serves as a proxy measure of aging and vulnerability to poor outcomes.
FI was developed by Dr. Kenneth Rockwood and Dr. Arnold Mitnitski at Dalhousie University in Canada.
FI is defined as the proportion of deficits present in an individual out of the total number of age-related health variables considered. A frailty index can be created in most secondary data sources related to health by utilizing health deficits that are routinely collected in health assessments. These deficits include diseases, signs and symptoms, laboratory abnormalities, cognitive impairments, and disabilities in activities of daily living.
Frailty Index (FI) = (number of health deficits present) ÷ (number of health deficits measured)
For example, a person with 20 of 40 deficits collected has an FI score of 20/40 = 0.5; whilst for someone with 10 deficits, the FI score is 10/40 = 0.25. The FI takes advantage of the high redundancy in the human organism. This is why it is replicable across different databases even when different items and different numbers of items are used. The standard procedure for creating a frailty index are found in an open-access publication.
There are several frailty indices, including a clinical deficits frailty index (FI-CD) and a biomarker-based frailty index (FI-B).
See also
Disability
Physiological functional capacity
References
Geriatrics
Gerontology
Medical scales | Frailty index | Biology | 315 |
74,289,294 | https://en.wikipedia.org/wiki/Idyll%20XXII | Idyll XXII, also called Διόσκουροι ('The Dioscuri'), is a poem by the 3rd-century BC Greek poet Theocritus. It is a hymn, in the Homeric manner, to Castor and Polydeuces.
Summary
This hymn to Castor and Polydeuces consists, first, of a prelude common to both, and secondly, of two main parts concerned one with Polydeuces and the other with Castor. The first of these, in a combination of the Epic style with the dialogue, tells how Polydeuces fought fisticuffs with Amycus on his way to Colchis, and the second how, when the brothers carried off the daughters of Leucippus, Castor fought Lynceus with spear and sword.
Analysis
Andrew Lang compares the "life and truth of the descriptions of nature, and of the boxing-match" in the Theocritean text with the "frigid manner" of Apollonius Rhodius on the same theme.
See also
Epyllion
References
Sources
Attribution:
Further reading
External links
Ancient Greek poems
3rd-century BC poems
Castor and Pollux | Idyll XXII | Astronomy | 253 |
40,202,629 | https://en.wikipedia.org/wiki/The%20Slow%20Mo%20Guys | The Slow Mo Guys is a science and technology entertainment web series from Thame, England, created and owned by Gavin Free, starring himself and Daniel Gruchy. It has been described as the biggest channel for slow motion videos on YouTube.
The series consists of a wide variety of things filmed in extreme slow motion using a range of Vision Research Phantom high-speed cameras, capable of shooting over 1,500,000 frames per second. The series premiered on 15 October 2010.
Format
The Slow Mo Guys is heavily influenced by Mythbusters; in a typical episode, Free and Gruchy attempt to film some sort of natural or physical phenomenon in extreme slow motion: subjects of the filming are often some type of spectacular chemical or physical reaction, stress tests of certain objects under extreme conditions, while some episodes simply aim for an aesthetically pleasing result, often by the use of rainbow-coloured paints. To emphasise the science angle, the pair wear lab coats. Because the original lab coats Free ordered were too small for Gruchy, Gruchy's lab coat tore; the torn off right sleeve has been carried on as a tradition on newer lab coats as well. Gruchy's lab coat is the more stained of the two, with Free's coat in fairer condition. The most prominent of the few stains on Free's lab coat is a blue paint smear on the right shoulder "autographed" by a Blue Man.
The episodes generally feature Free as the cinematographer and camera operator, and Gruchy, a former ammunition technician corporal in the British Army who served in Afghanistan, as the rigger and often also as the stuntman. Over the years, Gruchy suffered numerous injuries, such as a lacerated ear, a glass shard lodged in his finger, an oil burn and a fractured wrist; he jokingly noted that he has suffered more injuries during the filming of the show than during his tour in the Afghanistan war zone. Some episodes feature Gruchy explaining how some explosives work, such as grenades and detonation cord, allowing him to draw on his background in the military. Following the popularity of their most viewed video, Giant 6ft Water Balloon, Free and Gruchy have regularly produced further videos involving Gruchy in or around several-foot water balloons under the event of "Giant Balloon June".
The episodes are generally filmed in Free's backyard in Austin, Texas, usually with only the two of them involved. In the case of The Super Slow Show and Planet Slow Mo, as the budget of the show increased and more cast was involved, the experiments got larger and more elaborate; the availability of a designated camera crew allowed Free to participate in the stunts as well.
History
Inception
In 2006, Gavin Free joined Green Door Films, the first production house in Europe to utilise Phantom digital high-speed cameras as a source of slow motion, working as a data technician and camera operator. He began working on adverts, music videos, and films such as Hot Fuzz. In 2008, he was hired to direct the seventh season of the Rooster Teeth machinima series Red vs. Blue. Afterwards, he had decided to make a move to Austin, Texas and work full-time for Rooster Teeth, for which he needed to get a work visa; however, as he didn't go to university, his only option was an application for an O visa, a visa that requires an "extraordinary achievement" in arts or science.
Being a video/film producer, he decided to utilise his access to slow motion cameras to create The Slow Mo Guys along with his friend Daniel Gruchy, who he first met while working in a Waitrose in their home county of Oxfordshire. According to Free, the Slo Mo Guys name partially comes from a comment Richard Hammond made on the set of Top Gear:
Success
In April 2011, the channel was voted the winner of YouTube's On The Rise program, which highlights up-and-coming YouTube partners on the homepage. In September 2012, their episode involving crushing watermelons was featured on The Tonight Show.
On 20 February 2013, Free confirmed that the series had been picked up by Rooster Teeth for broadcast and that further episodes of the series would be released on Rooster Teeth's website, as well as the series' existing YouTube channel, with Free remaining as the sole owner of Slow Mo Guys. A best of compilation was released by Rooster Teeth Productions for home video on 10 September 2013.
In January 2014, in collaboration with GE Global Research, the R&D division of General Electric, they released a video showcasing the company's latest innovations, including superhydrophobic surfaces and how magnetic nanoparticles behave like liquid magnets. Two additional videos featuring them demonstrating MEMS and "cold spray" 3D painting technology were also released on the official GE YouTube channel.
The series has been featured as part of YouTube's "Rewind" year-in-review video in 2013, 2014, 2015, 2016, and 2017.
The series was used as part of a 2014 YouTube advertising campaign. The advertisements featuring Free and Gruchy were titled "You Make Every Second Epic". A large image of Free and Gruchy was printed on a London bus as part of the campaign, alongside TV commercials, billboards and Tube station posters.
The series was nominated for a Webby Award in Best Web Personality/Host (Online Film & Video) in 2016. At the 2016 Streamy Awards, the series won in the Cinematography category.
On 27 March 2020, Oculus TV premiered their eight-part series collaboration with The Slow Mo Guys called The Slow Mo Guys VR. In this show, people would be able to watch Free and Gruchy recreate their videos in 3D slow motion.
Several videos have been made in collaboration with other entertainers. This has included filming of a sabrage competition with Rhett & Link; dropping bowling balls with the Blue Man Group; and providing Will Smith (wearing Gruchy's lab coat) a flamethrower to use on cardboard cutouts of himself.
YouTube Originals
In 2018, Free and Gruchy launched their first YouTube Original, The Super Slow Show. This was essentially The Slow Mo Guys, but on a grander scale, featuring new equipment; larger stunts, such as crashing through walls; and special guests, including Dylan Sprouse and Mayim Bialik.
In 2019, Free and Gruchy launched their second YouTube Original, Planet Slow Mo, in which the duo would travel around the world and film special events and stunts. A trailer was released on 21 January, with the first episode airing on 23 January.
COVID-19
During the COVID-19 pandemic, as Gruchy lives in the United Kingdom, the international travel restrictions prevented him from travelling to Texas to take part in filming for about a year and a half. In video comments of later videos, Free would make a running joke about Gruchy digging a tunnel underneath the Atlantic Ocean to sneak into Texas. Gruchy would then reference the joke by digging himself out from the ground in the first video he was able join in again in 2022.
Dr. Anthony Fauci, then-head of the National Institute of Allergy and Infectious Diseases, appeared in an October 22, 2020 video in which he and Free advocated for "the importance of wearing masks and face coverings" to prevent the spread of COVID-19. Dr. Fauci subsequently described the video as "a perfect demonstration" of the need for people to wear face masks.
On February 4, 2021, Free appeared on behalf of the Slow Mo Guys on a Gates Notes-sponsored episode of PBS Digital Studios' Be Smart to promote herd immunity and COVID-19 vaccines.
Television
On 1 September 2022, Free and Gruchy's first television show, The Slow Mo Guys' Big Adventures, premiered on Sky Kids in the UK.
The ten-episode series features themed episodes about historical events such as the Wild West, the Viking era, and the first rocket launches.
Awards and nominations
References
External links
Merch Store
UK Government Sole Ownership Company Information
English comedy duos
British Internet celebrities
YouTube channels
Rooster Teeth channels
YouTube channels launched in 2010
English video bloggers
Slow motion | The Slow Mo Guys | Physics | 1,683 |
37,834,727 | https://en.wikipedia.org/wiki/Theta1%20Microscopii | {{DISPLAYTITLE:Theta1 Microscopii}}
θ1 Microscopii, Latinized as Theta1 Microscopii, is a suspected binary star system in the southern constellation of Microscopium. It is visible to the naked eye was a faint, white-hued point of light with an apparent visual magnitude of 4.82. The distance to this system is approximately 179 light years based on parallax.
The primary is an α2 CVn variable with a period of 2.125 days and a magnitude ranging from 4.77 to 4.87, as well as an Ap star, a chemically peculiar star with strong metallic lines in its spectrum. It is an A-type main-sequence star with a stellar classification of A7VpSrCrEu, where the suffix notation indicates abundance anomalies of strontium, chromium, and europium. The star is 437 million years old with 2.3 times the mass of the Sun and 2.4 times the Sun's radius. It is radiating 36 times the luminosity of the Sun from its photosphere at an effective temperature of 9,240 K.
Its companion is a magnitude 7.42 star at an angular separation of from the primary along a position angle of 46°, as of 2018.
References
A-type main-sequence stars
Ap stars
Microscopium
Microscopii, Theta1
CD-41 14475
203006
105382
8151
Alpha2 Canum Venaticorum variables | Theta1 Microscopii | Astronomy | 317 |
41,853,232 | https://en.wikipedia.org/wiki/Biotechnology%20Heritage%20Award | The Biotechnology Heritage Award recognizes individuals who have made significant contributions to the development of biotechnology through discovery, innovation, and public understanding. It is presented annually at the Biotechnology Innovation Organization (BIO) Annual International Convention by the Biotechnology Innovation Organization (BIO, formerly the Biotechnology Industry Organization) and the Science History Institute (formerly the Chemical Heritage Foundation). The purpose of the award is "to encourage emulation, inspire achievement, and promote public understanding of modern science, industry, and economics".
Recipients
The award is given yearly and was first presented in 1999.
Ivor Royston, 2020
Janet Woodcock, 2019
William Rastetter, 2018
John C. Martin, 2017
Stanley Norman Cohen, 2016
Moshe Alafi and William K. Bowes, 2015
Robert S. Langer, 2014
George Rosenkranz, 2013
Nancy Chang, 2012
Joshua S. Boger, 2011
Arthur D. Levinson, 2010
Robert T. Fraley, 2009
Henri A. Termeer, 2008
Ronald E. Cape, 2007
Alejandro Zaffaroni, 2006
Paul Berg, 2005
Leroy Hood, 2004
William J. Rutter, 2003
Walter Gilbert, 2002
Francis S. Collins and J. Craig Venter, 2001
Herbert Boyer and Robert A. Swanson, 2000
George B. Rathmann, 1999
Photo Gallery
See also
List of biology awards
References
Biology awards
American science and technology awards
Awards established in 1999
1999 establishments in the United States | Biotechnology Heritage Award | Technology | 283 |
77,402,447 | https://en.wikipedia.org/wiki/Thermo-acoustic%20instability | Thermo-acoustic instability refers to an instabiltiy arising due to acoustics field and unsteady heat release process. This instability is very relevant in combustion instabilities in systems such as rocket engines, etc.
Rayleigh criterion
A very simple mechanism of acoustic amplification was first identified by Lord Rayleigh in 1878. In simple terms, Rayleigh criterion states that amplification results if, on the average, heat addition occurs in phase with the pressure increases during the oscillation.. That is, if is the pressure perturbation (with respect to its mean value ) and is the rate of heat release per unit volume (with respect to its mean value ), then the Rayleigh criterion says that acoustic amplification occurs if
Rayleigh criterion is used to many explain phenomena such as singing flames in tubes, sound amplification in Rijke tube and others. In complex systems, Rayleigh criterion, may not ne strictly valid, as there exists many damping factors such as viscous/wall/nozzle/relaxation/homogeneous/particle damping, mean-flow effects, et, that are not accounted in Rayleigh's analysis.
See also
Darrieus–Landau instability
Diffusive–thermal instability
Rijke tube
References
Fluid dynamics
Combustion
Fluid dynamic instabilities | Thermo-acoustic instability | Chemistry,Engineering | 269 |
348,304 | https://en.wikipedia.org/wiki/Desktop%20metaphor | In computing, the desktop metaphor is an interface metaphor which is a set of unifying concepts used by graphical user interfaces to help users interact more easily with the computer. The desktop metaphor treats the computer monitor as if it is the top of the user's desk, upon which objects such as documents and folders of documents can be placed. A document can be opened into a window, which represents a paper copy of the document placed on the desktop. Small applications called desk accessories are also available, such as a desk calculator or notepad, etc.
The desktop metaphor itself has been extended and stretched with various implementations of desktop environments, since access to features and usability of the computer are usually more important than maintaining the 'purity' of the metaphor. Hence one can find trash cans on the desktop, as well as disks and network volumes (which can be thought of as filing cabinets—not something normally found on a desktop). Other features such as menu bars or taskbars have no direct counterpart on a real-world desktop, though this may vary by environment and the function provided; for instance, a familiar wall calendar can sometimes be displayed or otherwise accessed via a taskbar or menu bar belonging to the desktop.
History
The desktop metaphor was first introduced by Alan Kay, David C. Smith, and others at Xerox PARC in 1970 and elaborated in a series of innovative software applications developed by PARC scientists throughout the ensuing decade. The first computer to use an early version of the desktop metaphor was the experimental Xerox Alto, and the first commercial computer that adopted this kind of interface was the Xerox Star. The use of window controls to contain related information predates the desktop metaphor, with a primitive version appearing in Douglas Engelbart's "Mother of All Demos",
though it was incorporated by PARC in the environment of the Smalltalk language.
One of the first desktop-like interfaces on the market was a program called Magic Desk I. Built as a cartridge for the Commodore 64 home computer in 1983, a very primitive GUI presented a low resolution sketch of a desktop, complete with telephone, drawers, calculator, etc. The user made their choices by moving a sprite depicting a hand pointing by using the same joystick the user may have used for video gaming. Onscreen options were chosen by pushing the fire button on the joystick. The Magic Desk I program featured a typewriter graphically emulated complete with audio effects. Other applications included a calculator, rolodex organiser, and a terminal emulator. Files could be archived into the drawers of the desktop. A trashcan was also present.
The first computer to popularise the desktop metaphor, using it as a standard feature over the earlier command-line interface was the Apple Macintosh in 1984. The desktop metaphor is ubiquitous in modern-day personal computing; it is found in most desktop environments of modern operating systems: Windows as well as macOS, Linux, and other Unix-like systems.
BeOS observed the desktop metaphor more strictly than many other systems. For example, external hard drives appeared on the 'desktop', while internal ones were accessed clicking on an icon representing the computer itself. By comparison, the Mac OS places all drives on the desktop itself by default, while in Windows the user can access the drives through an icon labelled "Computer".
Amiga terminology for its desktop metaphor was taken directly from workshop jargon. The desktop was called Workbench, programs were called tools, small applications (applets) were utilities, directories were drawers, etc.
Icons of objects were animated and the directories are shown as drawers which were represented as either open or closed.
As in the classic Mac OS and macOS desktop, an icon for a floppy disk or CD-ROM would appear on the desktop when the disk was inserted into the drive, as it was a virtual counterpart of a physical floppy disk or CD-ROM on the surface of a workbench.
Paper paradigm
The paper paradigm refers to the paradigm used by most modern computers and operating systems. The paper paradigm consists of, usually, black text on a white background, files within folders, and a "desktop". The paper paradigm was created by many individuals and organisations, such as Douglas Engelbart, Xerox PARC, and Apple Computer, and was an attempt to make computers more user-friendly by making them resemble the common workplace of the time (with papers, folders, and a desktop). It was first presented to the public by Engelbart in 1968, in what is now referred to as "The Mother of All Demos".
From John Siracusa:
Back in 1984, explanations of the original Mac interface to users who had never seen a GUI before inevitably included an explanation of icons that went something like this: "This icon represents your file on disk." But to the surprise of many, users very quickly discarded any semblance of indirection. This icon is my file. My file is this icon. One is not a "representation of" or an "interface to" the other. Such relationships were foreign to most people, and constituted unnecessary mental baggage when there was a much more simple and direct connection to what they knew of reality.
Since then, many aspects of computers have wandered away from the paper paradigm by implementing features such as "shortcuts" to files, hypertext, and non-spatial file browsing. A shortcut (a link to a file that acts as a redirecting proxy, not the actual file) and hypertext have no real-world equivalent. Non-spatial file browsing, as well, may confuse novice users, as they can often have more than one window representing the same folder open at the same time, something that is impossible in reality. These and other departures from real-world equivalents are violations of the pure paper paradigm.
See also
Desktop environment
File browser
History of the GUI
Interface metaphor
Operating system
Skeuomorph
Tiling window manager
Virtual desktop
WIMP (computing)
Notes and references
External links
ArsTechnica article on the spatial Mac OS Finder
User interface techniques
User interfaces
Graphical user interfaces
Software architecture
Metaphors by type
fr:Environnement de bureau#Métaphore du bureau | Desktop metaphor | Technology | 1,268 |
2,685,369 | https://en.wikipedia.org/wiki/Zeta%20Tauri | Zeta Tauri (ζ Tauri, abbreviated Zeta Tau, ζ Tau) is a binary star in the zodiac constellation of Taurus, the Bull. It has an apparent visual magnitude of about 3.0, which is bright enough to be seen with the naked eye. Parallax measurements place it at a distance of roughly 440 light-years from the Sun.
The two components are designated Zeta Tauri A (officially named Tianguan ) and Zeta Tauri B.
Nomenclature
ζ Tauri (Latinised to Zeta Tauri) is the star's Bayer designation; it also bears the Flamsteed designation of 123 Tauri. The designations of the two components as Zeta Tauri A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).
In Chinese astronomy, Zeta Tauri is called 天關, Pinyin: Tiānguān, formerly transliterated Tien Kwan, meaning Celestial [Frontier] Gate, an asterism within the Net (畢宿 Bì Xiù) mansion). 天關 (Tiānguān) has also been transliterated as Tien Kwan. (Technically, Tiānguān refers not just to Zeta Tauri but to the Celestial Gate asterism of which Zeta Tauri is the main star, alongside 113, 126, 128, 129, 130 and 127 Tauri .) In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Tianguan for the component Zeta Tauri A on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.
Properties
Zeta Tauri is a single-lined spectroscopic binary system, which means the two components are orbiting so close to each other that they can not be resolved with a telescope. Instead, the orbital motion of the primary component is indicated by Doppler effect shifts in the absorption lines in its spectrum. The two components are separated by an estimated distance of about 1.17 astronomical units, or 117% of the distance from the Earth to the Sun. They are following circular orbits with a period of nearly 133 days.
Compared to the Sun, the primary, Zeta Tauri A, is an enormous star with more than 11 times the mass and 5–6 times the radius. It is rotating rapidly with a projected rotational velocity of . The companion, Zeta Tauri B, has about 94% the mass of the Sun, although it is unknown whether this is a main-sequence star, a neutron star, or a white dwarf. If it is a main sequence star, then the mass indicates it may have a stellar classification of G4.
The spectrum of the primary component has a stellar classification of B2 IIIpe. A luminosity class of 'III' indicates this is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. The 'p' suffix indicates an unspecified chemical peculiarity in the spectrum, while 'e' is used for stars that display emission lines. For Be stars such as this, the emission lines are produced by a rotating circumstellar disk of gas, made of material that has been ejected from the star's outer envelope. An oscillatory pattern in this spectrum is being caused by a single-armed spiral density wave in the disk. The disk may be precessing from the gravitational influence of the secondary component.
Zeta Tauri shows variation in its spectrum and brightness. The General Catalogue of Variable Stars lists it as an eclipsing variable and a Gamma Cassiopeiae variable, but it may not be either. Hrvoje Božić and Krešimer Pavlovski, of Hvar Observatory in Croatia, monitored the brightness of Zeta Tauri from 1981 to 1986 and noticed an eclipse like effect in the light curve. A latter study of all the available photometric data, including from the Hipparcos spacecraft, failed to confirm the presence of eclipses.
See also
Chinese constellations
White Tiger (mythology)
References
Tauri, Zeta
B-type giants
Gamma Cassiopeiae variable stars
Spectroscopic binaries
Taurus (constellation)
Tianguan
Tauri, 123
1910
026451
037202
BD+21 0908 | Zeta Tauri | Astronomy | 905 |
5,482,995 | https://en.wikipedia.org/wiki/Pelargonium%20graveolens | Pelargonium graveolens is a Pelargonium species native to the Cape Provinces and the Northern Provinces of South Africa, Zimbabwe and Mozambique. Common names include rose geranium, sweet scented geranium, old-fashioned rose geranium, and rose-scent geranium.
Etymology
Pelargonium comes from the Greek πελαργός pelargos which means stork. Another name for pelargoniums is stork's-bills due to the shape of their fruit. The specific epithet graveolens refers to the strong-smelling leaves.
Common names
Pelargonium graveolens is also known by taxonomic synonyms Geranium terebinthinaceum Cav. and Pelargonium terebinthinaceum (Cav.) Desf. "Rose geranium" is sometimes used to refer to Pelargonium incrassatum (Andrews) Sims or its synonym Pelargonium roseum (Andrews) DC. – the herbal name. Commercial vendors often list the source of geranium or rose geranium essential oil as Pelargonium graveolens, regardless of its botanical name.
Description
Pelargonium graveolens is an erect, aromatic, multi-branched subshrub, that grows up to 1.5 m and has a spread of 1 m. The leaves are deeply incised, velvety and soft to the touch (due to glandular hairs). The above-ground parts of the plant are more or less hairy and glandular. The alternately arranged leaves are divided into petioles and leaf blades. The leaf blade is soft, heart-shaped and palmately divided, blunt with lobed to coarsely toothed leaf lobes. The natural form smells of mint. Some cultivars have a scent similar to rose petals, although the leaf shape and scent vary (others have little or no scent). Some leaves are deeply incised and others less so, being slightly lobed like P. capitatum. The flowers vary from pale pink to almost white which appear from late winter to summer, peaking in spring.
Distribution
It is native to Mozambique and Zimbabwe in southern, tropical Africa, and South Africa (Cape Province, Transvaal). Pelargoniums have been cultivated in South Africa and Namibia for at least 200 years. The plant is also found in the Canary Islands, Corsica, Costa Rica, Cuba, the Dominican Republic, Haiti, southwestern Mexico, and Puerto Rico, where it has been introduced.
Cultivars and hybrids
Many plants are cultivated under the species name "Pelargonium graveolens" but differ from wild specimens as they are of hybrid origin (probably a cross between P. graveolens, P. capitatum and/or P. radens). There are many cultivars and they have a wide variety of scents, including rose, citrus, mint and cinnamon as well as various fruits. Cultivars and hybrids include:
P. 'Graveolens' (or Pelargonium graveolens hort.) - A rose-scented cultivar; possibly a hybrid between P. graveolens and P. radens or P. capitatum. This cultivar is often incorrectly labeled as Pelargonium graveolens (the species). The main difference between the species and this cultivar is the dissection of the leaf. The species' has about 5 lobes but the cultivar has about 10.
P. 'Citrosum' - A lemony, citronella-scented cultivar, similar to P. 'Graveolens'. It is meant to repel mosquitos and rumour has it that it was made by genetically bonding genes from the citronella grass but this is highly unlikely.
P. 'Cinnamon Rose' - A cinnamon-scented cultivar.
P. 'Dr Westerlund' - A lemony rose-scented cultivar, similar to P. 'Graveolens'.
P. 'Graveolens Bontrosai' - A genetically challenged form; the leaves are smaller and curl back on themselves and the flowers often do not open fully. Known as P. 'Colocho' in the US.
P. 'Grey Lady Plymouth' - A lemony rose-scented cultivar similar to P. 'Lady Plymouth'. The leaves are grey–green in colour.
P. 'Lady Plymouth' - A minty lemony rose-scented cultivar. A very popular variety with a definite mint scent. Possibly a P. radens hybrid.
P. 'Lara Starshine' - A lemony rose-scented cultivar, similar to P. 'Graveolens' but with more lemony scented leaves and reddish pink flowers. Bred by Australian plantsman Cliff Blackman.
P. 'Lucaeflora' - A rose-scented variety, much more similar to the species than most other cultivars and varieties.
P. × melissinum - The lemon balm pelargonium (lemon balm - Melissa officinalis). This is a hybrid between P. crispum and P. graveolens.
P. 'Mint Rose' - A minty rose-scented cultivar similar to P. 'Lady Plymouth' but without the variegation of the leaves and lemony undertones.
P. 'Secret Love' - An unusual eucalyptus-scented cultivar with pale pink flowers.
P. 'Van Leeni' - A lemony rose-scented cultivar, similar to P. 'Graveolens' and P. 'Dr Westerlund'.
Others known: Camphor Rose, Capri, Granelous and Little Gem.
Uses
Both the true species and the cultivated plant may be called rose geranium – pelargoniums are often called geraniums, as they fall within the plant family Geraniaceae, and were previously classified in the same genus. The common P. 'Graveolens' or P. 'Rosat' has great importance in the perfume industry. It is cultivated on a large scale and its foliage is distilled for its scent. Pelargonium distillates and absolutes, commonly known as "geranium oil", are sold for aromatherapy and massage therapy applications. They are also sometimes used to supplement or adulterate more expensive rose oils. As a flavoring, the flowers and leaves are used in cakes, jams, jellies, ice creams, sorbets, salads, sugars, and teas. In addition, it is used as a flavoring agent in some pipe tobaccos, being one of the characteristic "Lakeland scents."
Rose geranium, known as Mâatercha or Ätarcha in Morocco, is used as a flavorful herb to complement spearmint tea. It is often added alongside spearmint or other minty herbs to enhance the overall flavor profile of the tea, adding a floral and aromatic note to the brew.
In Cyprus, where it is known as , it is used to flavour and scent the sugar syrup in apricot preserves, known as .
Chemical constituents
A modern analysis listed the presence of over 50 organic compounds in the essential oil of P. graveolens from an Australian source. Analyses of Indian geranium oils indicated a similar phytochemical profile, and showed that the major constituents (in terms of % composition) were citronellol + nerol and geraniol.
Gallery
References
graveolens
Medicinal plants
Perfume ingredients
Essential oils
Flora of Mozambique
Flora of Zimbabwe
Flora of the Cape Provinces
Flora of the Northern Provinces
Crops originating from South Africa
Taxa named by Charles Louis L'Héritier de Brutelle | Pelargonium graveolens | Chemistry | 1,586 |
43,779,604 | https://en.wikipedia.org/wiki/Murexide%20test | The murexide test is an analytical technique to identify the presence of caffeine and other purine derivatives in a sample. These compounds do not respond to the common alkaloid identification tests such as Dragendorff's reagent. In this test, crude drugs (to be identified) are mixed with a tiny amount of potassium chlorate and a drop of hydrochloric acid. The sample is then evaporated to dryness and the resulting residue is exposed to ammonia vapour. Purine alkaloids produce a pinkish-purple color in this test due to formation of murexide (ammonium purpurate; appears purple in pure state), which the test is named after.
In pure form, murexide appears purple, but when it is produced by reaction of acidified solutions of purines and ammonia, various shades of purple and pink are produced.
Uses
Murexide test is a color test for uric acid and some other purines. The (solid) sample is first treated with small volume of a concentrated acid such as hydrochloric acid, nitric acid, which is slowly evaporated away; subsequent addition of ammonia (NH3) gives a purple color if uric acid was present, due to formation of murexide, or a yellow color that turns to red on heating if xanthine or its derivatives are present.
References
Analytical reagents | Murexide test | Chemistry | 294 |
43,220,205 | https://en.wikipedia.org/wiki/53%20Piscium | 53 Piscium, abbreviated as 53 Psc, is a star in the zodiac constellation of Pisces. With an apparent magnitude of about 5.9, it is just barely visible to the naked eye. parallax measurements made by the Hipparcos spacecraft place the star at a distance of about 930 light-years (284 parsecs) away.
The spectral type of 53 Piscium is B2.5IV, meaning it is a B-type subgiant. It is 5.4 times more massive than the Sun, and has a luminosity of almost . Its surface temperature is over 17,000 K, typical of a B-type star.
53 Piscium is a Beta Cephei variable, varying by 0.01 magnitudes just under every two hours. For that reason it has been given the AG Piscium. It has also been found to have some variability in common with slowly pulsating B stars.
References
Pisces (constellation)
Piscium, 053
B-type giants
Beta Cephei variables
002903
Piscium, 53
0155
003379
Durchmusterung objects | 53 Piscium | Astronomy | 241 |
22,358,224 | https://en.wikipedia.org/wiki/Picture%20%28mathematics%29 | In combinatorial mathematics, a picture is a bijection between skew diagrams satisfying certain properties, introduced by in a generalization of the Robinson–Schensted correspondence and the Littlewood–Richardson rule.
References
Algebraic combinatorics
Combinatorial algorithms | Picture (mathematics) | Mathematics | 54 |
25,483,183 | https://en.wikipedia.org/wiki/Interference%20engine | An interference engine is a type of 4-stroke internal combustion piston engine in which one or more valves in the fully open position extends into any area through which the piston may travel. By contrast, in a non-interference engine, the piston does not travel into any area into which the valves open. Interference engines rely on timing gears, chains, or belts to prevent the piston from striking the valves by ensuring that the valves are closed when the piston is near top dead center. Interference engines are prevalent among modern production automobiles and many other four-stroke engine applications; the main advantage is that it allows engine designers to maximize the engine's compression ratio. However, such engines risk major internal damage if a piston strikes a valve due to failure of camshaft drive belts, drive chains, or drive gears.
Timing gear failure
In interference engine designs, replacing a timing belt in regular intervals (manufacturers recommend intervals ranging from 60,000 to 104,000 miles) or repairing chain issues as soon as they are discovered is essential, as incorrect timing may result in the pistons and valves colliding and causing extensive internal engine damage. The piston will likely bend the valves, or, if a piece of valve or piston is broken off within the cylinder, the broken piece may cause severe damage within the cylinder, possibly affecting the connecting rods. If a timing belt or chain breaks in an interference engine, mechanics check for bent valves by performing a leak-down test of each cylinder or by checking the valve gaps. A very large valve gap points to a bent valve. Repair options depend on the extent of the damage. If the pistons and cylinders are damaged, the engine must be rebuilt or replaced. If the valves are bent but there is no other damage, replacing the bent valves, rebuilding the cylinder head, and replacing the timing belt/chain components may be sufficient.
References
External links
List of vehicles with interference engines that use a timing belt.
Internal combustion engine | Interference engine | Technology,Engineering | 389 |
66,924,980 | https://en.wikipedia.org/wiki/Gilbert%20Tshiongo%20Tshibinkubula%20wa%20Ntumba | Gilbert Tshiongo Tshibinkubula wa Ntumba (19 August 1942 – 1 February 2021) was a Congolese engineer, politician, and civil servant.
Tshiongo was born on 19 August 1942 in Lusambo, present-day Sankuru province, in Belgian Congo. He graduated with vocational and technical degrees in electromechanics in 1960.
Professionally, Tshiongo spent much of his career at Regideso, the country's public sector water delivery utility. In 1962, Tshiongo joined Regideso as the head of electromechanical and hydraulic plants in Kabinda. He later became the President, CEO, and director general of Regideso.
Tshiongo served as Governor of the former Kasai-Occidental province from April 2006 to October 2006. He was elected to the National Assembly, representing the Dimbelenge Territory constituency in Kasaï-Central province. In February 2011, Tshiongo was appointed national Minister of Energy in the second cabinet of Prime Minister Adolphe Muzito, under President Joseph Kabila's administration.
Tshiongo died from an illness and COVID-19 in Kinshasa, Democratic Republic of the Congo, on 1 February 2021, at the age of 78.
References
1942 births
2021 deaths
Government ministers of the Democratic Republic of the Congo
Members of the National Assembly (Democratic Republic of the Congo)
Governors of Kasai-Occidental
Democratic Republic of the Congo engineers
Electrical engineers
People from Kasaï-Central
People from Sankuru
21st-century Democratic Republic of the Congo people
Deaths from the COVID-19 pandemic in the Democratic Republic of the Congo | Gilbert Tshiongo Tshibinkubula wa Ntumba | Engineering | 346 |
5,590,879 | https://en.wikipedia.org/wiki/NGC%202500 | NGC 2500 is a barred spiral galaxy in the constellation Lynx which was discovered by William Herschel in 1788. Much like the local group in which our own Milky Way galaxy is situated, NGC 2500 is part of the NGC 2841 group of galaxies which also includes NGC 2541, NGC 2537 and NGC 2552. It has a H II nucleus and exhibits a weak inner ring structure.
References
External links
Barred spiral galaxies
2500
04165
22525
Lynx (constellation) | NGC 2500 | Astronomy | 95 |
4,812,799 | https://en.wikipedia.org/wiki/List%20of%20rail%20accidents%20%28before%201880%29 |
17th century
1650
England – Whickham, County Durham. Two boys die when they are run over by a wagon on a wooden coal wagonway. While such tramway accidents are not generally listed as rail accidents (note the lack of accidents listed for the next 163 years) this is sometimes cited as the earliest-known railway accident.
1810s
1813
February – United Kingdom – A 13-year-old boy named Jeff Bruce is killed whilst running alongside the Middleton Railway tracks. The Leeds Mercury reports that this would "operate as a warning to others".
1815
15 July – United Kingdom – 1815 Philadelphia train accident – Thirteen or sixteen people, mainly spectators, are killed, and 40 are injured by the boiler explosion of the experimental locomotive "Brunton's Mechanical Traveller" on the Newbottle Waggonway at Philadelphia, County Durham.
1818
28 February – United Kingdom – The driver is killed on the Middleton Railway in Hunslet, Leeds, West Yorkshire when Salamanca's boiler explodes, as a result of the force of the explosion, he was "carried, with great violence, into an adjoining field the distance of one hundred yards." "This was the result of the driver tampering with the safety valves."
1820s
1821
5 December – United Kingdom – David Brook, a carpenter, is walking home from Leeds, Yorkshire along the Middleton Railway in a sleet storm when he is run over, with fatal results, by the steam engine of a coal train.
1827
United Kingdom – An unnamed woman from Eaglescliffe, County Durham, England (believed to have been a blind beggar woman) is "killed by the steam machine on the railway". This is said to be the first case of a woman being killed in a railway collision.
1828
19 March – United Kingdom – The boiler of Stockton and Darlington Railway locomotive No. 5 explodes at Simpasture Junction, County Durham. One person is killed.
July 1 – United Kingdom – The boiler of Stockton and Darlington railway locomotive Locomotion No. 1 explodes at station, County Durham. One person is killed.
1829
4 September – United Kingdom – "A poor fellow incautiously placed himself in the way of a locomotive engine, which was driving waggons on the Liverpool and Manchester Railway in Salford, when the wheel went over one of his legs, which was literally cut off. He was carried to a surgeon's in the neighbourhood, but no effectual aid could be given to him, nor the bleeding staunched, and he died."
1830s
1830
15 September – United Kingdom – William Huskisson becomes the first widely reported passenger train death. During the ceremonial opening of the Liverpool and Manchester Railway, while standing on the track at Parkside, he is struck and fatally injured by the locomotive Rocket. (Locomotives did not yet have whistles.)
1831
8 February – United Kingdom – William Tewburn was a guard on an overnight goods train of the Liverpool and Manchester Railway, pulled by the Twin Sisters locomotive which arrived at Liverpool Road, in Manchester at 2 am, where the unfortunate victim got aboard the tender unbeknownst to the engineer, who started moving the locomotive to take on coke and water, one of these short lurching trips caused the benumbed guard to lose his grip, and he fell under first the tender and then the locomotive, virtually cutting him in half.
17 June – United States – After the pressure safety valve is tied down by the train's fireman, the locomotive Best Friend of Charleston suffers a boiler explosion at Charleston, South Carolina, killing him, scalding the engineer, and injuring three others. The locomotive was the first engine of the South Carolina Canal and Railroad Company.
21 October – United Kingdom – On the Warrington & Newton Railway. Mr. Kitchingman had a garden that backed onto the railway at Dallam-brook. He was on the train with a friend and decided to jump out at his house, but was dragged under the wheels of the following coach, which mangled his leg, which had to be amputated. He later succumbed to his injuries and expired.
1833
1 February – United Kingdom – At Parr Moss, west of Newton-le-Willows on the Liverpool & Manchester Railway, an eastbound train is stopped by the bursting of a fire tube in the locomotive. Passengers get off to see what has happened, and some of them stand on the westbound track where the escaping steam blocks them from seeing (or being seen from) a train approaching from Bolton. Four are run over by the westbound train, three of them killed instantly and the fourth reported as unlikely to survive.
8 November – United States – Hightstown rail accident – The carriages of a Camden & Amboy passenger train derail in the New Jersey countryside between Spotswood and Hightstown when an axle breaks on a car due to an overheated journal. One car overturns, killing two people and injuring fifteen. Among the injured is Cornelius Vanderbilt, who will later head the New York Central Railroad. Uninjured in the coach ahead is former U.S. President John Quincy Adams, who continues on to the nation's capital the next day.
1834
12 February – United Kingdom – A boiler explosion on a Middleton Colliery locomotive at Hunslet, Yorkshire kills one person.
1836
2 October – United States – A broken axle of a Cincinnati-bound train throws a woman and a child onto the track where they are both dragged and run over. The woman perishes, but the child manages to survive, though seriously injured.
11 October – France – An employee of the line from Saint-Étienne to Lyon falls on a track and is decapitated by a train. The first train accident in France.
1837
11 August – United States – 1837 Suffolk head-on collision - The first head-on collision to result in passenger fatalities occurred on the Portsmouth and Roanoke Railroad near Suffolk, Virginia, when an eastbound lumber train coming down a grade at speed rounded a sharp curve and smashed into the morning passenger train from Portsmouth, Virginia. The first three of the thirteen stagecoach-style cars were smashed, killing three daughters of the prominent Ely family and injuring dozens of the 200 onboard returning from a steamboat cruise. An engraving depicting the moment of impact was published in Howland's Steamboat Disasters and Railroad Accidents in 1840.
1838
7 August – United Kingdom – A ticket inspector, Thomas Port, falls from a moving London and Birmingham Railway passenger train at Harrow, Middlesex. Both his legs are amputated following the accident.
October – United Kingdom – A collision involving an experimental engine which Dionysius Lardner is allowed to operate on the Great Western Railway kills a "pupil" of Lardner.
1839
2 February – United Kingdom – Charlotte Carrad was killed by a train heading for Slough on the Great Western Railway, eight months after this section, the first of the GWR, had opened. She was trying to cross the track at Langley to pick turnip tops in a field. She had seen the train, Hurricane, with three carriages, coming at about but hurried down the public footpath to get across the track. She reached the further rail when the engine struck her on the shoulder. Her friend, who was with her, found her in the ditch on the other side of the track. There was a little sign of life, but she died a minute or two later, her neck vertebrae having been dislocated.
1840s
1840
4 May – United States – One passenger was killed and several others injured when a lattice bridge over rain-swollen Catskill Creek collapsed under the weight of a Canajoharie and Catskill Railroad train en route from Catskill, New York, to Cairo, New York.
7 August – United Kingdom – Howden rail crash, Five passengers are killed when a casting falls from a wagon and derails the carriages of a Hull and Selby Railway passenger train.
September – United Kingdom – A North Midland Railway passenger train is derailed between South Wingfield and , Derbyshire. Two passengers are killed.
September – United Kingdom – An Eastern Counties Railway passenger train is in a rear-end collision with another at Old Ford, Essex. One person is killed.
10 November – United Kingdom – Two employees of the Birmingham and Gloucester Railway lose their lives when the boiler of the 2-2-0 steam locomotive Surprise explodes at Bromsgrove, Worcestershire.
11 November – United Kingdom – A York and North Midland Railway luggage train is in a rear-end collision with a passenger train at Taylor's Junction, Yorkshire. Two passengers are killed.
1841
5 October – United States – Two Western Railroad passenger trains are in a head-on collision between Worcester, Massachusetts and Albany, New York. A conductor and a passenger are killed and seventeen passengers are injured.
24 December – United Kingdom – Sonning Cutting railway accident – a Great Western Railway Paddington to Bristol train including goods wagons and open passenger wagons runs into a landslide in a cutting. Nine passengers are killed and sixteen are injured, leading to calls for better protection for passengers.
1842
8 May – France – Versailles rail accident – Following the King's fete celebrations at the Palace of Versailles, a train returning to Gare Montparnasse, Paris derails at Meudon, Hauts-de-Seine due to a broken axle on the leading locomotive. The wreckage catches fire, killing between 52 and 200 people, including the explorer Jules Dumont d'Urville.
1843
6 January – United Kingdom – A collision between two North Midland Railway trains at Barnsley, Yorkshire killed one person. The only passenger to be killed travelling by train in the United Kingdom that year.
10 March – Netherlands – During a test drive a locomotive derailed on a incompletely closed railway bridge near Warmond. One person was killed. This was the first railway accident in the Netherlands.
United Kingdom – A locomotive boiler explosion on the Hartlepool Railway kills one person, a member of the public travelling illegally on the footplate.
1844
1 May – United Kingdom – The boiler of Newcastle and Carlisle Railway locomotive Adelaide explodes at Carlisle, Cumberland. Two people are injured.
December 11 – United Kingdom – The boiler of South Eastern Railway locomotive No. 78 Forrester explodes as it hauls a freight train near , Surrey. Both crew are killed.
1845
28 January – United Kingdom – The boiler of Newcastle and Carlisle Railway locomotive Venus exploded whilst it was hauling a freight train.
28 January – United Kingdom – The boiler of Manchester and Leeds Railway locomotive No. 27 Irk explodes at Miles Platting, Lancashire.
28 July – United Kingdom – A passenger train is run into by a steam locomotive at , Kent, injuring about 30 people.
1846
20 January – United Kingdom – A bridge over the River Medway between and , Kent, England, collapses while a South Eastern Railway freight train is passing over it. The driver is killed.
9 July – United Kingdom – A Clarence Railway engine standing in a branch line of the Stockton and Darlington Railway suddenly began to move down the incline and collided with some waggons of another Clarence engine. Four men were crushed between the carriages and were severely injured. One died at the scene.
20 November – United Kingdom – During the construction of the Blackburn, Darwen and Bolton Railway, the boiler of ex-Stockton and Darlington Railway locomotive No. 18 Shildon explodes at , Lancashire.
23 November – United Kingdom – Elizabeth Coleman, aged eleven years, was killed on the Eastern Counties Railway. The deceased was, it appeared, endeavouring to cross the line at a point near the Roydon station where the Lockroad crosses the line on a level when she was struck by the buffer of a Cambridge train and killed upon the spot. The jury returned a verdict of "Accidental death."
1847
24 May – United Kingdom – Dee bridge disaster – Five people are killed and nine are injured when the carriages of a -to- train falls into the River Dee following the collapse of a bridge. One of the supporting cast-iron girders had cracked in the centre and given way. The locomotive and tender manage to reach the other side of the bridge, which was engineered by Robert Stephenson. The accident causes his reputation to be questioned. The collapse led to a re-evaluation of the use of cast iron in railway bridges; many bridges have to be demolished or reinforced.
28 June – United Kingdom – A North Union Railway locomotive suffers a boiler explosion, injuring one person.
1848
25 April – United Kingdom – The boiler of a North Midland Railway locomotive explodes at Normanton, Derbyshire, scalding three people.
10 May – United Kingdom – 1848 Shrivenham rail collision – Six passengers are killed, and thirteen are injured at , Berkshire when a Great Western Railway express train runs into two wagons on the line. The horse-box and cattle van had been pushed onto the main line by two porters to free a wagon turntable. Although the locomotive was undamaged, the side of the leading carriage was torn out.
1849
Whitsuntide – United Kingdom – An East Lancashire Railway passenger train is in a rear-end collision with an excursion train. Despite efforts to protect its rear, another excursion train is in a rear-end collision with the passenger train.
27 June – United Kingdom – The boiler of Great Western Railway locomotive Goliah explodes whilst it is hauling a freight train on the South Devon Railway at Plympton, Devon. One person is killed.
1850s
1850
2 February – United Kingdom – The firebox of a York, Newcastle and Berwick Railway locomotive collapses whilst the locomotive is hauling a freight train near Darlington, County Durham. Two people are killed.
26 March – United Kingdom – The boiler of a London and North Western Railway locomotive explodes at Wolverton, Buckinghamshire due to tampering of the safety valves. One person is injured.
June – United Kingdom – The boiler of a Midland Railway locomotive explodes at Kegworth, Derbyshire.
1 August – United Kingdom – When three Scottish Central Railway excursion trains are scheduled to arrive in rapid succession at Cowlairs, Lanarkshire, the second one stops on a crossover and must reverse to clear it; but although time interval working is in use, no one goes back to protect it and the third train crashes into it, killing five people.
United Kingdom – A Great Western Railway excursion train collides with a horsebox that had escaped from a siding at , Wiltshire. Following this accident, The Great Western Railway provides trap points and scotch blocks at all sidings exiting on to main lines.
United Kingdom – A Midland Railway train is in a rear-end collision with an excursion train at station, Yorkshire because a signal is lit at night.
United Kingdom – The boiler of a York and North Midland Railway locomotive explodes at Staddlethorpe, Yorkshire, derailing the locomotive. Two people are injured.
1851
21 January – Germany – The 1851 Avenwedde rail accident was the first German rail accident with several fatalities and the worst rail accident at that time point. Three people died.
30 April – United Kingdom – Sutton Tunnel railway accident - A Birkenhead, Lancashire and Cheshire Junction Railway passenger train runs into the rear of another inside Sutton Tunnel, Cheshire. The train that was run into was pushing another in front of it; both had stalled. Six people are killed and "a great number" are injured.
6 June – United Kingdom – A London, Brighton and South Coast Railway train is derailed on a bridge between Brighton and Lewes by a sleeper placed across a rail, killing five people.
1852
12 July – United Kingdom – Burnley railway accident – A 35-coach school excursion train from Goole arrives at Burnley on the Lancashire and Yorkshire Railway, where it is far too long for the platform track. The engines are detached and the train left coasting slowly downhill into a long siding. As the station is understaffed, two friends of the staff have been asked to help out. One of them briefly lets go of a set of weighted points, misrouting the train into the dead-end platform track, where it crashes into the buffers before it can be braked. Of 800 people on board, four are killed.
29 July – United Kingdom – On the London and North Western Railway, a locomotive is brought into Shrewsbury shed for a minor repair, but the steam is still engaged when the fire is dropped. After the engine is repaired and fired up, it is left unattended for 20 minutes at a shift change. It runs away onto the main line and later collides with a standing train at Donnington, Shropshire, killing one passenger.
3 August – United Kingdom – The ashpan of the locomotive falls off a Rugby-to-Birmingham train at Hampton on the London and North Western Railway, derailing a van and one coach, which collide with a train on the other track. Two passengers are killed and several injured.
September 25 – United Kingdom – the boiler of an Eastern Counties Railway locomotive explodes.
4 October – United Kingdom – A South Eastern Railway passenger train is derailed between and , East Sussex, England, when the formation is flooded and washed away. Both engine crew are injured.
25 November – United Kingdom – A Great Western Railway train hauled by locomotive Lynx is derailed at Gatcombe, Gloucestershire.
1853
6 January – United States – Franklin Pierce rail accident – A train carrying President-elect Franklin Pierce, his wife Jane and their son Benjamin derailed and toppled off an embankment near Andover, MA. Franklin and Jane suffered minor injuries, but their son Benjamin was killed.
4 March – United States – A train carrying emigrants near Mount Union, Pennsylvania, is rear-ended by a mail train; boilers rupture, scalding seven people to death and having the highest death toll in the United States in that time. The engineer of the mail train was reportedly asleep when the collision occurred.
4 March – United Kingdom – A Lancashire and Yorkshire Railway train derails on a deteriorated section of track near Dixon Fold, killing the driver and five passengers.
6 March – United Kingdom – The boiler of a London and North Western Railway locomotive explodes at Longsight, Lancashire. Six people are killed, and the engine shed is severely damaged.
17 March – United Kingdom – The boiler of a London, Brighton and South Coast Railway locomotive explodes at , East Sussex.
27 March – United States – Wheeling rail disaster – A loose rail results in two Baltimore and Ohio Railroad passenger cars tumbling down a cliff in West Virginia. 8 to 17 die and 39 are wounded.
23 April – United States – A train runs through an open drawbridge over Rancocas Creek. No fatalities are reported.
25 April – United States – Greater Grand Crossing rail collision- A collision near Chicago results in the deaths of 18.
6 May – United States – Norwalk rail accident – The first major American railroad bridge disaster occurs when a New Haven Railroad engineer neglects to check for an open swing bridge signal. The locomotive, four cars, and part of a fifth car run through the open bridge and plunge into the Norwalk River, Connecticut. Forty-six passengers are crushed to death or drowned, and about 30 others are severely injured.
9 May – United States – A cornfield meet in the New Jersey Meadowlands results in the deaths of two people. One of the engineers was not forewarned about the change in time schedule which resulted in this.
12 August – 1853 Providence and Worcester head-on collision – United States – Two Providence and Worcester Railroad passenger trains are in a head-on collision at Valley Falls, Rhode Island. Thirteen people are killed and 50 are injured. This is believed to be the earliest wreck photographed, with the daguerreotype taken by a Mr. L. Wright of Pawtucket forming the basis for an engraving a fortnight later in The Illustrated News of New York.
September – United Kingdom – An Eastern Counties Railway freight train comes to a halt near , Suffolk due to a locomotive failure. The driver of another freight train deliberately ignores a red signal and consequently his train is in a rear-end collision with the first train.
5 October – Ireland – 1853 Straffan rail accident – A Great Southern and Western Railway express passenger train fails south of , County Kildare due to a broken piston rod on the locomotive. The train is run into by a following freight train due to the failure of the guard to act to protect the line to the rear of the broken-down train. Eighteen people are killed.
United Kingdom – The boiler of a Midland Railway locomotive explodes near Bristol, Gloucestershire whilst the locomotive is hauling a freight train.
1854
4 July - United States - Two locomotives collided on the Baltimore and Susquehanna Railroad near the Riderwood and Ruxton communities in Towson, Maryland, resulting in 30 deaths and the reorganization of the railroad into the Northern Central Railroad.
24 August – United Kingdom – A South Eastern Railway excursion train is in a rear-end collision with a light engine at Windmill Bridge, Croydon, Surrey. Three passengers are killed.
27 October – Canada – Jeannette's Creek train wreck – A Great Western Railway passenger train runs into the rear of a gravel train at Baptiste Creek, Ontario. Fifty-two people are killed, and at least 48 people are injured.
1855
February-March – United Kingdom – On Monday 12 February 1855 large portions of the South Devon Railway sea wall were washed away. Despite repair work starting promptly four days later more of the sea wall and a long section of line were also washed away. Passengers were obliged to leave their trains and carry their luggage some distance to join another. A temporary viaduct was constructed by the resident engineer, Mr. Margery, and was in operation within a couple of weeks which allowed the through operation of coaches, pulled by hand and rope, although some nervous passengers still alighted and walked.
29 August – United States – 1855 Camden & Amboy rail accident – A southbound Camden and Amboy Rail Road passenger train, backing up on a single track near Burlington, New Jersey, to make room for a northbound express, hit a horse-drawn carriage. The rearmost passenger car derailed, and the succeeding cars crashed into it, derailed, and plunged into a ditch. All four passenger cars were demolished. Twenty-four people died, and between 65 and 100 were injured.
1 November – United States – Gasconade Bridge train disaster – A bridge over the Gasconade River at Gasconade, Missouri collapses under a Pacific Railroad excursion train during the celebrations of the line's opening. Thirty-one people are killed, and hundreds are seriously injured.
12 September – United Kingdom – A light engine is dispatched from on the wrong line and is in a head-on collision with a South Eastern Railway passenger train. Four people are killed, and many are injured.
15 December – United States – The boiler of the New York Central Railroad locomotive Dewitt Clinton explodes, killing the engineer and fireman.
United Kingdom – A South Eastern Railway train is derailed at Bricklayers' Arms Junction, Surrey, when a pointsman moves a set of points under it.
1856
6 May – Panama – 1856 Panama Railroad accident- A train with over 500 passengers derailed near Aspinwall in Panama. Thirty to forty people were killed and 70 to 80 were injured.
29 May – Germany – The Jupiter locomotive crashed into the Potsdamer Havel during a test run due to a swing bridge that was not closed.
21 June – United Kingdom – A South Eastern Railway passenger train derails between and , Kent, killing the driver and injuring the fireman and a passenger.
17 July – United States – Great Train Wreck of 1856 – Two North Pennsylvania Railroad passenger trains are in a head-on collision at Camp Hill, Pennsylvania, including a train on an excursion from a Sunday school at St. Michael's Catholic Parish in Philadelphia. Fifty-nine people are killed in the crash and subsequent fire, with over 100 people injured, some of whom consequently die. One of the two trains' conductors commits suicide the same day; the other is indicted for manslaughter but acquitted.
10 August – Netherlands – Schiedam train accident – Two passenger trains collide resulting in three deaths.
6 October – United Kingdom – Accident at Salisbury resulted in 2 deaths and 1 injury.
1857
12 March – Canada – Desjardins Canal disaster: A bridge over the Desjardins Canal collapses when the axle of a Great Western Railway passenger train from Toronto to Hamilton breaks as the train is passing across it. Fifty-nine people are killed by trauma or drowning after being thrown into the frozen canal.
27 June – United Kingdom – 1857 Lewisham rail crash: A South Eastern Railway passenger train runs into the rear of another at Lewisham, Kent due to an error by the signalman at , Kent. Eleven people are killed, and 30 are injured.
1858
6 May – United Kingdom – A passenger train from Plymouth on the just-opened Cornwall Railway derails just before the Grove Viaduct near St Germans and the engine and two cars plunged toward the water. Three railwaymen are killed.
11 May – United States – A bridge some from Utica, New York gave way when two trains, including a New York Central, express bound for Cincinnati, passed over it. Nine passengers died, including some who drowned, and fifty were injured.
15 May – United States – A Lafayette & Indianapolis Railroad train accident on a bridge over Potato Creek, about south-east of Lafayette near Colfax, Indiana. The engineer, Jacob Beitinger (Beidinger), the fireman, Patrick Maloney (Moloney), and conductor James W. Irwin were killed.
30 June – United Kingdom – A South Eastern Railway passenger train is derailed at , Kent. Three people are killed.
11 August – United Kingdom – A passenger train runs into the buffers ar station, Kent. Twenty people are injured.
23 August – United Kingdom – Round Oak rail accident – An Oxford, Worcester and Wolverhampton Railway passenger train becomes divided following a coupling failure. The rear portion runs away and collides with a following passenger train at station, Stourbridge, Worcestershire. Fourteen people are killed. There are 50 serious injuries and 170 minor injuries.
6 September – France – On the Chemin de fer de Paris à Saint-Germain, a 10-car atmospheric railway train is returning by gravity with about 300 festival-goers from Saint-Germain-en-Laye to Le Vésinet, where it will couple to a steam locomotive to continue to Paris. Due to a combination of errors, it runs away and crashes into the locomotive's tender. A crew member and two passengers are killed, and at least 40 people are injured.
1859
28 June – United States – South Bend train wreck – At South Bend, Indiana, the Springbrook Bridge collapses as a Michigan Southern Railroad express passenger train passes over it. The locomotive and two carriages smash into the mudbank below. Forty-two people are killed and 50 are injured.
August – United Kingdom – An axle of the engine of the London, Tilbury and Southend Railway fractures at Stanford-le-Hope, Essex. One male passenger is killed.
1860s
1860
20 February – United Kingdom – The tyre of an Eastern Counties Railway locomotive breaks as it hauls a passenger train through Tottenham station. The train is derailed, killing seven people.
16 May – United States – On the Florida, Atlantic and Gulf Central Railroad about west of Jacksonville, Florida, a train encountered a drove of cattle which threw the train off track. Lumber, logs trunks and passengers were "heaped up in almost inextricable confusion." Nearly every person on board was more or less injured. Three people were killed in the crash.
6 September – United Kingdom – Helmshore rail accident – A Lancashire and Yorkshire Railway excursion train becomes divided at Helmshore, Lancashire. Sixteen carriages run away and crash into the following train. Eleven people are killed.
26 September – United Kingdom – Bull bridge accident – A cast iron bridge collapses under a Midland Railway freight train at Bullbridge, Derbyshire.
16 November – United Kingdom – A London and North Western Railway mail train overruns signals and crashes into the rear of a cattle train at Atherstone, Warwickshire. Ten people are killed; mostly Irish drovers asleep in the brake van at the rear of the cattle train.
1861
January – United Kingdom – A London Chatham and Dover Railway passenger train was derailed at , Kent. One person was killed.
11 June – United Kingdom – Wootton bridge collapse: A cast iron bridge near Kenilworth, Warwickshire collapses under a London and North Western Railway freight train. Both crew of the locomotive are killed.
4 July – United Kingdom – As the westbound Irish Mail approaches Easenhall bridge, past Rugby, at about , its 2-2-2 LNWR Bloomer Class locomotive is completely destroyed in an explosion due to badly corroded boiler plates. Luckily no passengers are even injured, but of the railwaymen and postal crew on board, one is killed and three are injured.
25 August – United Kingdom – Clayton Tunnel rail crash: A London, Brighton and South Coast Railway excursion train crashes into the rear of another inside the Clayton Tunnel, West Sussex due to a combination of driver's, signalman's and operating errors. Twenty-three people are killed, and 176 are injured in what was then the deadliest railway accident in the United Kingdom.
29 August – United Kingdom – A South Durham and Lancashire Union Railway excursion train returning from Windermere to Darlington derails west of Bowes, injuring a number of passengers. The injured driver and fireman are trapped beneath the locomotive for several hours till rescued. The driver died on September 8, 1861, from his injuries.
2 September – United Kingdom – Kentish Town rail accident: A North London Railway excursion train collides with a London and North Western Railway freight train at Kentish Town, Middlesex due to a signalman's error. Sixteen people are killed, and 317 are injured.
3 September – United States – Platte Bridge Railroad Tragedy: A Hannibal and St. Joseph Railroad train is wrecked after bushwhackers sabotage the supports of a bridge over the Platte River in Missouri. At least seventeen people are killed, and about 100 are injured.
December – United Kingdom – A London, Chatham and Dover Railway train hauled by locomotive Eclipse is derailed at Teynham, Kent due to the elongation of the gap at a rail joint in cold weather.
1862
May – United Kingdom – A London, Chatham and Dover Railway passenger train is derailed at , Kent due to defective track. Three people are killed.
13 October – United Kingdom – Winchburgh rail crash – Two Edinburgh and Glasgow Railway passenger trains are in a head-on collision at Winchburgh, Linlithgowshire due to a pointsman's error. Fifteen people are killed and 35 are injured.
August - United States - In Manassas, Virginia, a passenger train derailed after sabotage on the tracks during the Manassas Station Operations (Stonewall Jackson), 2 people were injured.
1863
19 February – United States – Chunky Creek train wreck: The Hercules on the Southern Rail Road crashes into the Chunky River in Newton County, Mississippi. The train was headed for Vicksburg where Confederate forces were in need of reinforcements. The Hercules derailed on a damaged bridge and fell into the cold, murky depths. At least 40 passengers were killed. Some victims were rescued by soldiers from the 1st Choctaw Battalion who were camped nearby.
28 February – India – An accident on the East Indian Railway results in a bridge collapsing somewhere on the line between Ahmoodpur and Rampur.
1864
15 January – United States – A train crossing the Little Juniata River near Birmingham, Pennsylvania experiences a derailment. The train and proceeding coaches plummet down a ravine. Stoves in the coaches overturn and ignite a fire. While many injuries are reported, miraculously, no one is killed.
5 May – United Kingdom – At Colne on the Midland Railway, a 0-6-0 engine being prepared to work a goods train to Leeds suffers a boiler explosion, killing the driver and badly injuring the fireman. A woman is struck by a fragment in her home away.
9 May – United Kingdom – At Bishop's Road station on the Metropolitan Railway — a 0-6-0 locomotive borrowed from the Great Northern Railway suffers a boiler explosion. Nobody is killed but the station suffers major damage and injuries extend to a passenger in another train two tracks away.
29 June – Canada – St-Hilaire train disaster – An immigrant train fails to stop at a danger signal and attempts to cross an open swing bridge and falls into the Richelieu River at Beloeil, Quebec. Ninety-nine people are killed and 100 are injured. , this still stands as the rail accident with the largest death toll in Canada.
15 July – United States – Shohola train wreck – An Erie Railroad passenger train carrying Confederate prisoners-of-war is in a head-on collision with a coal train near Shohola Township, Pennsylvania due to a dispatcher's error. Between 60 and 72 people are killed (official toll is 65 killed).
16 August – United States – An Erie Railroad freight train runs into the rear of a passenger train between Turner's Station and Sloatsburg, New York. A third train runs into the wreckage. Seven people are killed.
21 September – United States – A Pennsylvania Railroad passenger train runs into the rear of a stopped freight train at Thompsontown, Pennsylvania. The wreckage then catches fire. At least six people are killed and thirteen are injured.
16 December – United Kingdom – A South Eastern Railway ballast train becomes divided inside Blackheath Tunnel, Kent. An express passenger train runs into the rear portion, killing five people, with two others dying later and many injured.
1865
12 May – United Kingdom – An accident occurred on the Irish North Western railway near Enniskillen. A goods train left Derry and ran off the rails. The engine driver, J. McCabe, and the stoker, C. Craven, were killed. Some bullocks in a waggon were also killed.'
7 June – United Kingdom – Rednal rail crash – A Great Western Railway excursion train is derailed at Rednal, Shropshire due to excessive speed on track under maintenance. Thirteen people are killed and 30 are injured.
9 June – United Kingdom – Staplehurst rail crash – A South Eastern Railway boat train is derailed on a bridge over the River Beult at Staplehurst, Kent after track workers misread a timetable and remove a rail. Ten people are killed, and 49 are injured. Author Charles Dickens is amongst the survivors.
1866
30 April – United Kingdom – A South Eastern Railway passenger train collides with some goods wagons at Caterham Junction, Surrey due to a signalman's error. Four people are killed.
10 June – United Kingdom – Welwyn Tunnel rail crash: A Great Northern Railway freight train is stopped in Welwyn North Tunnel due to a burst fire tube. A Midland Railway freight train following it in the same direction crashes into it, and a third freight train going the other way crashes into the wreckage. All three trains are totally destroyed by fire, but the only deaths are two of the crew members.
27 August – United States – A boiler explosion on the Petaluma and Haystack Railroad at Petaluma Station kills the engineer and three others and wrecks the railroad's only locomotive.
19 December – United Kingdom – During the construction of the new Smithfield Market building adjacent to an open-air section of the Metropolitan Railway in London, a girder falls onto a passing train and three passengers are killed. This is the first fatal accident on an underground train.
1867
29 June – United Kingdom – Warrington rail crash – A London and North Western Railway passenger train is in collision with a freight train at Walton Junction, Warrington, Cheshire due to a signalman's error. Eight people are killed and 70 are injured. Lack of interlocking between signals and points is a major contributory factor in the accident.
9 August – Ireland – A bridge collapses under a passenger train at Bray, County Wicklow. Four people are killed and twelve are injured.
18 December – United States – Angola Horror – The Buffalo-bound New York Express of the Lake Shore and Michigan Southern derails its last coach, and it plunges off a truss bridge into Big Sister Creek just after passing Angola, New York. The next car is also pulled from the track and rolls down the far embankment. Stoves set both coaches on fire and 49 are killed. The cars were relatively easy to derail because they were "compromise cars" designed to run on slightly different track gauges, a practice soon afterwards prohibited.
1868
1 February – United Kingdom – An embankment on the approach to the Caersws Railway Bridge on the Cambrian Railways is washed out by flooding, derailing a mail and goods train running from Shrewsbury to Aberystwyth. The two enginemen are killed.
20 August – United Kingdom – Abergele rail disaster: A London and North Western Railway freight train is being shunted at , Denbighshire. During shunting operations, six wagons run away downhill towards , where they collide with an express passenger train. Five of the wagons are carrying paraffin, which explodes and sets the wreck of the passenger train on fire. Thirty-three people are killed, the driver of the express is severely burned.
5 November – United Kingdom – Great Western Railway locomotive Rob Roy crashes into the rear of a cattle train at Awse Junction, near Newnham, Gloucestershire and is derailed.
10 November - Czech Republic - A collision occurs between Cerhovice and Ujezd involving a passenger train and a freight train. 35 passengers die as a result, and 80 more are injured.
1869
3 February – Czech Republic – A passenger train heading to Prague derails near Úvaly sending multiple coaches down an embankment. 10 are injured in the accident and the conductor of the train is the only reported fatality.
23 April – United States – Hollis, New York: A Long Island Rail Road passenger train is derailed by a broken rail. The rail curls into a "snakehead" and rips out the bottom of one of the cars. Six people are killed, and fourteen injured.
14 November – United States – San Leandro, California: An errant switchman and poor visibility due to fog led to a head-on collision between an eastbound passenger train from Oakland, with a sleeper car, on the Western Pacific Railroad and an Alameda-bound Alameda Railroad passenger train. Among the fourteen killed was Judge Alexander W. Baldwin of the U.S. District Court of Nevada.
1870s
1870
21 June – United Kingdom – Newark rail crash: The axle of a wagon of a Midland Railway freight train breaks at Newark, Nottinghamshire, derailing the train. The derailed wagons foul an adjacent line. An excursion train collides with the debris. Eighteen people are killed and 40 are injured.
14 September – United Kingdom – Tamworth rail crash: A London and North Western Railway mail train is diverted into a siding at station, Staffordshire due to a signalman's error. The train crashes through the buffers and ends up in the River Anker. Three people are killed.
26 November – United Kingdom – An express train crashed into a stationary freight train at Harrow and Wealdstone station on the London and North Western Railway, killing eight people.
6 December – United Kingdom – A collision between two North Eastern Railway trains at Brockley Whins claims five lives and injures 37 people. The cause is a pointsman's error made possible by the lack of interlocking between points and signals.
12 December – United Kingdom – Stairfoot rail accident: Due to errors while shunting, ten waggons from a Manchester, Sheffield and Lincolnshire Railway freight train run away and collide with a passenger train at , Yorkshire. Fifteen people are killed, and 59 are injured.
United Kingdom – A North Eastern Railway freight train overruns signals and is in collision with a London and North Western Railway mail train at St. Nicholas Crossing, Carlisle, Cumberland. Five people are killed, many more are injured. The driver of the North Eastern Railway train was intoxicated.
1871
6 February – United States – A freight train on the Hudson River Railroad, carrying both crude and refined oil, suffers a broken axle. Because the crew have not threaded the required rope for communication from caboose to locomotive, the engineer is unaware, and the train keeps moving until it derails at the Wappinger Creek drawbridge, New Hamburg, New York. They and the drawbridge tender try to warn the following Pacific Express passenger train, but they are not in time, and the collision and resulting fire kill 22 people.
9 August – United States – A bridge collapses under a Maine Central Railroad Company passenger train at Bangor, Maine. One person is killed and 30 are injured.
26 August – United States – Great Revere train wreck of 1871: A series of dispatching errors allow the Eastern Railroad's Portland Express to run into the rear of a stalled local train at Revere, Massachusetts. The wreckage catches fire; 29 people are killed and 57 are injured. Several prominent Boston citizens are killed, bringing much national publicity to the accident.
1872
2 October – United Kingdom – Kirtlebridge rail crash – A Caledonian Railway express passenger train collides with a freight train performing shunting operations at Kirtlebridge, Dumfriesshire. Twelve people are killed and fifteen are injured.
24 December – United States – Two passenger cars of a Pennsylvania Railroad passenger train fall off a bridge in Portland, New York due to a "broken flange on the tender". Thirty people are killed and at least eighteen are injured.
1873
30 March – United Kingdom – A Great Northern Railway excursion train collides with two carriages at Bourne, Lincolnshire. No one was seriously injured, but the carriages and crossing gates were destroyed.
19 April – United States – A passenger train is derailed at Meadow Brook, Rhode Island, near Wood River Junction, due to a bridge being washed away in a dam collapse. Nine passengers are killed.
6 May – Austria-Hungary – A passenger train is derailed at Budapest-Nyugati Railway Terminal. Twenty-six people are killed.
2 August – United Kingdom – Wigan rail crash – A London and North Western Railway passenger train derails at Wigan North Western station, possibly due to excessive speed over facing points. Thirteen people are killed and 30 are injured.
12 August – Italy – A Società per le strade ferrate romane passenger train in service between Rome and Florence derails near the town of Orte (Lazio) after hitting two cattle standing on the tracks. Two people are killed and more than 40 injured.
2 December – United Kingdom – At Menheniot on the Cornwall Railway, a porter-signalman named Pratt instructs a down goods train to proceed by calling out "Right away, Dick" to its guard, Richard Wills. Unfortunately, an up goods train is also at the station and its guard, Richard Scantlebury, thinks the instruction is for him; by the time Pratt realizes this, Scantlebury has already told his driver to start. Their train collides with another down goods before reaching St Germans, injuring several crewmen and killing one.
1874
27 January – United Kingdom – Bo'ness Junction rail crash – A North British Railway express passenger train collides with a freight train at Bo'ness Junction, Stirlingshire. Sixteen people are killed and 28 are injured.
10 September – United Kingdom – Thorpe rail accident – Two Great Eastern Railway passenger trains are in a head-on collision at Thorpe St. Andrew, Norfolk, due to irregular dispatching procedures. Twenty-five people are killed and more than 100 injured. The accident leads directly to the introduction of automatic control systems to manage traffic on single-track railways.
24 December – United Kingdom – Shipton-on-Cherwell train crash – A Great Western Railway passenger train is derailed by a fractured wheel at Shipton-on-Cherwell, Oxfordshire. Thirty-four people are killed, and 69 are injured. Poor communications and the lack of continuous brakes exacerbate the disaster.
1875
6 July – Chile – A bridge collapses beneath the overnight train between Valparaíso and Santiago in Chile, killing nine people.
28 August – United Kingdom – A passenger train overruns signals and is in a rear-end collision with an excursion train at Kildwick, Yorkshire. Seven people are killed and 39 are injured.
15 November – Sweden – Lagerlunda rail accident – Unclear signalling leads to a head-on-collision between two passenger trains near Lagerlunda, Östergötland. Nine people are killed.
18 November – United Kingdom – Two London, Chatham and Dover Railway trains collide at , London.
1876
21 January – United Kingdom – Abbots Ripton rail accident: A Great Northern Railway express passenger train passes a signal jammed in the clear position during a blizzard and is in a rear-end collision with a freight train at Abbots Ripton, Huntingdonshire, and a train in the other direction then collides with the wreckage. Thirteen passengers are killed and 59 people are injured.
14 April – United Kingdom – A Great Northern Railway express train runs into a mail train at Corby, Lincolnshire because signals are jammed in a clear position in a blizzard.
16 June – United States – A trestle bridge collapses under a Blue Ridge Railroad train bound from Belton, South Carolina, to Anderson Court House, South Carolina. All five people on board are killed.
7 August – United Kingdom – Radstock rail accident – A variety of errors lead to two Somerset and Dorset Joint Railway passenger trains being involved in a head-on collision at Radstock, Somerset. Fifteen passengers are killed.
23 December – United Kingdom – A Great Northern Railway express train overruns signals and crashes into a number of wagons at Arlesley Sidings, Bedfordshire. Six people are killed.
29 December – United States – Ashtabula River railroad disaster: A bridge collapses under a Lake Shore and Michigan Southern Railway passenger train at Ashtabula, Ohio. The train falls into the frozen creek below. A fire is started by the car stoves. Dozens of people are killed, but sources disagree as to how many—perhaps as many as 92. The famous hymn-writer Philip Bliss and his wife are believed to be amongst an estimated 19 to 25 unidentified victims.
1877
25 March – United Kingdom – An express passenger train is derailed at , Northumberland due to faulty track.
27 March – United States – A train on the Jackson, Lansing, and Saginaw Railroad, fatally injures one.
4 October – United States – A mixed train of the Pickering Valley Railroad falls from a washed-out embankment near Kimberton, Pennsylvania, killing seven and injuring dozens.
1878
11 January – United Kingdom – Great Northern Railway – The Flying Scotsman is in a collision with a freight train at Welwyn Garden City, Hertfordshire, after which a local passenger train collides with the wreckage.
15 January – United States – 1878 Tariffville train crash – A rail bridge in Tariffville, Connecticut fails resulting in the train falling into an icy river. 13 are killed and 70 are injured.
21 May – United States – A Kansas Pacific R.R. Freight train is caught in a bridge washout at Kiowa Creek, Colorado; 3 killed.
31 August – United Kingdom – A London, Chatham and Dover Railway passenger train collides with goods wagons at , Kent due to errors by a shunter and the two guards of a freight train. Five people are killed.
8 October – United States – Wollaston disaster – A train in Quincy, Massachusetts carrying over 1,000 passengers runs over an open switch resulting a serious derailment.
1879
15 January – United Kingdom – Two hounds from the Pytchley Hunt were killed and a number injured while chasing a fox near the Kilsby Tunnel on the London and Birmingham Railway, when a train ran through the pack.
17 January – France – A runaway locomotive collides into a passenger train in La Chapelle. One of the passengers is Paul Gachet who survives the wreck with an injury to his liver.
18 (or 25) January – Belgium – Two passengers and the engine driver were killed when the express train from Brussels to Lille and Calais left the line at Bassilly.
22 January – United Kingdom – A heavy goods train from Glasgow was travelling too fast on the Tay Rail Bridge and a number of carriages left the track when the guard applied the brakes. The same bridge would be the scene of a much worse accident less than a year later (see below).
22 January – United Kingdom – Three carriages left the line after a collision between trains from Farringdon Street and Aldersgate Street at Snow-Hill, on the London, Chatham and Dover Railway.
5 (or 12) February – United Kingdom – A cattle train ran into a ballast train near Widnes Junction on the London and North Western Railway. The driver and stoker jumped out as the cattle train engine ran down the embankment.
4 April – United Kingdom – A goods train ran off the Highland Railway line, near Perth, destroying of track.
17 May – United Kingdom – An express train from Glasgow came off the line when it collided with a goods train near Dunfermline railway station on the North British Railway. The driver of the express died.
13 June – United Kingdom – A train carrying show cattle from the Royal Cornwall Show was hit by a Plymouth-to-Penzance goods train at Truro railway station. One van was "smashed to pieces", there was one minor injury to the goods train driver, and none to the cattle.
26 July – United Kingdom – Lancashire and Yorkshire Railway. The 7:30 train for Warrington failed to stop and hit a Rainford train at Wigan Station. Several third-class carriages were knocked off the rails.
July/August – France – An accident between Nancy and Paris killed five people and injured eleven.
16 August – France – A passenger train and a goods train collided near Montséret killing fifteen and injuring thirty-six.
29 August – United Kingdom – The Scottish mail train derailed between Hendon and Mill Hill due to the track subsiding following heavy rain. The driver and fireman both severely injured.
24 September – United Kingdom – A Great Western Railway train from Plymouth to Tavistock derailed outside Marsh Mills railway station.
27 September – United Kingdom – London, Brighton and South Coast Railway B1 class 2-4-0 locomotive 174 Fratton suffered a boiler explosion at , East Sussex while hauling a passenger train. The accident was due to the incorrect setting of its safety valves. One person killed and two injured.
12 October – United Kingdom – The 10:10 am passenger train from Derby ran into seven empty carriages at Nottingham station, resulting in eight injured and considerable damage to the rolling stock.
1 December – United Kingdom – North Liverpool Extension Line. The train from Walton hit an engine at Brunswick Dock, Liverpool. One man killed and four injured.
28 December – United Kingdom – Tay Bridge disaster – The Tay Rail Bridge collapses in a violent storm while a North British Railway passenger train is crossing it. There were no survivors, with the total estimated at seventy-five lives lost, although the real total was fifty-nine. The subsequent investigation concludes that "the bridge was badly designed, badly constructed and badly maintained" and lays the major blame on the designer, Sir Thomas Bouch. William McGonagall produces his epic poem The Tay Bridge Disaster to commemorate the event. The disaster shocks engineers into creating an improved crossing both on the Tay, as well as the famous Forth Bridge.
See also
List of London Underground accidents
Rail transport
References
Sources
External links
Rail accidents 1880
19th-century railway accidents | List of rail accidents (before 1880) | Technology | 10,548 |
13,464,118 | https://en.wikipedia.org/wiki/Gary%20Taubes | Gary Taubes (born April 30, 1956) is an American journalist, writer, and low-carbohydrate / high-fat (LCHF) diet advocate. His central claim is that carbohydrates, especially sugar and high-fructose corn syrup, overstimulate the secretion of insulin, causing the body to store fat in fat cells and the liver, and that it is primarily a high level of dietary carbohydrate consumption that accounts for obesity and other metabolic syndrome conditions. He is the author of Nobel Dreams (1987); Bad Science: The Short Life and Weird Times of Cold Fusion (1993); Good Calories, Bad Calories (2007), titled The Diet Delusion (2008) in the UK and Australia; Why We Get Fat: And What to Do About It (2010); The Case Against Sugar (2016); and The Case for Keto: Rethinking Weight Control and the Science and Practice of Low-Carb/High-Fat Eating (2020). Taubes's work often goes against accepted scientific, governmental, and popular tenets such as that obesity is caused by eating too much and exercising too little and that excessive consumption of fat, especially saturated fat in animal products, leads to cardiovascular disease.
Biography
Born in Rochester, New York, Taubes studied physics at Harvard University (BS, 1977) and aerospace engineering at Stanford University (MS, 1978). After receiving a master's degree in journalism at Columbia University in 1981, Taubes joined Discover magazine as a staff reporter in 1982. Since then he has written numerous articles for Discover, Science and other magazines. Originally focusing on physics issues, his interests have more recently turned to medicine and nutrition.
His brother, Clifford Henry Taubes, is the William Petschek Professor of Mathematics at Harvard University.
Scientific controversies
Taubes' books have all dealt with scientific controversies.
Nobel Dreams takes a critical look at the politics and experimental techniques behind the Nobel Prize-winning work of physicist Carlo Rubbia.
In Bad Science: The Short Life and Weird Times of Cold Fusion, he chronicles the short-lived media frenzy surrounding the Pons–Fleischmann cold fusion experiments of 1989. He opines in the book that heat generation in the experiments of Drs. Martin Fleischmann and Stanley Pons was due entirely to difference in ionic conductivity of deuterated salts solutions compared to normal aqueous solutions.
He also formulated an allegation of fraud regarding the results from John Bockris's research group.
Diet advocacy
Taubes gained prominence in the low-carb diet debate following the publication of his 2002 New York Times Magazine piece "What if It's All Been a Big Fat Lie?". The article, which questioned the efficacy and health benefits of low-fat diets, was seen as defending the Atkins diet against the medical establishment, and it became extremely controversial. Some scholars interviewed for the article complained that Taubes misinterpreted their words or treated them out of context. Taubes himself stated: "[E]ven though I knew the article would be the most controversial article the Times Magazine ran all year, [the reaction] still shocked me." The Center for Science in the Public Interest published a rebuttal to the Times article in its November 2002 newsletter. Cardiologist John W. Farquhar commented that "Gary Taubes tricked us all into coming across as supporters of the Atkins diet."
Taubes is an advocate of eating beef. Beef industry leader Amanda Radke has written in Beef Daily that "Today's best beef advocates wear a variety of hats [...] like Nina Teicholz or Gary Taubes who turn against conventional health advice to promote diets rich in animal fats and proteins".
Good Calories, Bad Calories
In 2007, Taubes published his book Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease (published as The Diet Delusion in the UK). This book proposed that a hypothesis — that dietary fat is the cause of obesity and heart disease — became dogma, and claims to show how the scientific method was circumvented so a contestable hypothesis could remain unchallenged. The book uses data and studies compiled from more than a century of dietary research to support what Taubes calls "the alternative hypothesis."
Taubes' argument is that the medical community and the U.S. federal government have relied upon misinterpreted scientific data on nutrition to build the prevailing paradigm about what constitutes healthful eating. Taubes argues that — contrary to conventional nutritional science — it is a carbohydrate-laced diet, augmented with sugar, that leads to heart disease, type 2 diabetes, obesity, cancer, and other "maladies of civilization." In the Epilogue to Good Calories, Bad Calories on page 454, Taubes sets out ten "inescapable" conclusions, the first of which is, "Dietary fat, whether saturated or not, is not a cause of obesity, heart disease, or any other chronic disease of civilization."
Reviewing Good Calories, Bad Calories, obesity researcher George A. Bray, wrote that the book "...has much useful information and is well worth reading" but that "obese people clearly eat more than do lean ones" and that "some of the conclusions that the author reaches are not consistent with current
concepts about obesity."
In 2007, New York Times science writer John Tierney cited Taubes's book Good Calories, Bad Calories and discussed information cascades and the role of physiologist Ancel Keys in widely held beliefs related to diet and fat. Tierney follows Taubes in noting that a 2001 Cochrane meta-analysis of low-fat diets found that they had "no significant effect on mortality". Harriet A. Hall, however, has criticized Taubes for selectively quoting the meta-analysis, and, writing for Science-Based Medicine, states that although it is possible some of Taubes' hypotheses may be borne out by subsequent evidence, his idea that carbohydrate restriction can lead to weight loss independently of calorie restriction is "simply wrong".
The Case Against Sugar
Taubes authored The Case Against Sugar in 2016. The book argues that sugar is an addictive drug and is the cause of obesity and many health-related problems. It was positively reviewed by chef and food-writer Dan Barber, who described Taubes's writing as "inflammatory and copiously researched". Food journalist Joanna Blythman also praised the book, noting "his clear and persuasive argument that obesity is a hormonal disorder, switched on by sugar, is one that urgently needs wider airing."
Harriet Hall, who is known as a skeptic in the medical community, wrote that Taubes made a compelling case against sugar but the evidence was inconclusive.
C. Albert Yeung in the Journal of Public Health described the book as very informative but insufficient to draw any conclusion and a "polemic, not a balanced scientific review."
NuSI
In September, 2012, Taubes and Peter Attia launched the Nutrition Science Initiative (NuSI), a nonprofit organization they described as "a Manhattan Project-like effort to solve" the problem of obesity. The project set out to validate the "carbohydrate-insulin hypothesis", a model by which carbohydrate is proposed to be uniquely fattening because of its influence on insulin levels.
A pilot study funded by NuSI was conducted in 2014 by a team led by NIH researcher Kevin Hall, and produced evidence which did not support the hypothesis. In 2017, Kevin Hall wrote that the hypothesis had been falsified by experiment.
Not long after the completion of that study NuSI was confronted with a number of issues. They lost a significant source of funding; co-founder Peter Attia left the organization.
In 2018, NuSI was described as having "two part-time employees and an unpaid volunteer hanging around".
Awards
Taubes has won the Science in Society Journalism Award of the National Association of Science Writers three times and was awarded an MIT Knight Science Journalism Fellowship for 1996–97. He is a Robert Wood Johnson Foundation independent investigator in health policy.
Selected bibliography
(Also published as The Diet Delusion )
References
External links
1956 births
Living people
American nutritionists
American science writers
Cold fusion
Columbia University Graduate School of Journalism alumni
Harvard John A. Paulson School of Engineering and Applied Sciences alumni
Low-carbohydrate diet advocates
Stanford University alumni
Writers from Rochester, New York
20th-century American Jews
21st-century American Jews
Discover (magazine) people | Gary Taubes | Physics,Chemistry | 1,789 |
29,439,514 | https://en.wikipedia.org/wiki/Holometer | The Fermilab Holometer in Illinois is intended to be the world's most sensitive laser interferometer, surpassing the sensitivity of the GEO600 and LIGO systems, and theoretically able to detect holographic fluctuations in spacetime.
According to the director of the project, the Holometer should be capable of detecting fluctuations in the light of a single attometer, meeting or exceeding the sensitivity required to detect the smallest units in the universe called Planck units. Fermilab states: "Everyone is familiar these days with the blurry and pixelated images, or noisy sound transmission, associated with poor internet bandwidth. The Holometer seeks to detect the equivalent blurriness or noise in reality itself, associated with the ultimate frequency limit imposed by nature."
Craig Hogan, a particle astrophysicist at Fermilab, states about the experiment, "What we’re looking for is when the lasers lose step with each other. We’re trying to detect the smallest unit in the universe. This is really great fun, a sort of old-fashioned physics experiment where you don’t know what the result will be."
Experimental physicist Hartmut Grote of the Max Planck Institute in Germany states that although he is skeptical that the apparatus will successfully detect the holographic fluctuations, if the experiment is successful "it would be a very strong impact to one of the most open questions in fundamental physics. It would be the first proof that space-time, the fabric of the universe, is quantized."
Holometer has started, in 2014, collecting data that will help determine whether the universe fits the holographic principle.
The hypothesis that holographic noise may be observed in this manner has been criticized on the grounds that the theoretical framework used to derive the noise violates Lorentz-invariance. Lorentz-invariance violation is however very strongly constrained already, an issue that has been very unsatisfactorily addressed in the mathematical treatment.
The Fermilab holometer has found also other uses than studying the holographic fluctuations of spacetime. It has shown constraints on the existence of high-frequency gravitational waves and primordial black holes.
Experimental description
The Holometer will consist of two 39 m arm-length power-recycled Michelson interferometers, similar to the LIGO instruments. The interferometers will be able to be operated in two spatial configurations, termed "nested" and "back-to-back". According to Hogan's hypothesis, in the nested configuration the interferometers' beamsplitters should appear to wander in step with each other (that is, the wandering should be correlated); conversely, in the back-to-back configuration any wandering of the beamsplitters should be uncorrelated. The presence or absence of the correlated wandering effect in each configuration can be determined by cross-correlating the interferometers' outputs.
The experiment started one year of data collection in August 2014. A paper about the project titled Now Broadcasting in Planck Definition by Craig Hogan ends with the statement "We don't know what we will find."
A new result of the experiment released on December 3, 2015, after a year of data collection, has ruled out Hogan's theory of a pixelated universe to a high degree of statistical significance (4.6 sigma). The study found that space-time is not quantized at the scale being measured.
References
External links
Fermilab Holometer
Science and technology in the United States
Experimental physics
Experimental particle physics
Fermilab
2014 inventions
Fermilab experiments | Holometer | Physics | 741 |
62,410,922 | https://en.wikipedia.org/wiki/College%20Daily | College Daily () is a new media publication whose primary audience is Chinese students studying in North America.
Overview
College Daily was founded in 2014 and expanded from there. The primary audience is overseas Chinese students, particularly those studying in North America.
In August 2019, The New Yorker published a story about College Daily, calling it a "post-truth" publication where Chinese students in the U.S. receive their news." The story noted that College Daily had aggregated and reproduced content sourced from Infowars and RT as well as state propaganda outlets such as Sputnik News.
As of August 2019 the College Daily employed 30 in their Beijing office and 15 at their New York City office.
CollegeDaily has raised a total of $3M in funding over 1 round. This was a Series A round raised on Nov 28, 2017.
CollegeDaily is funded by 3 investors. Tencent Holdings and CMC Capital Group are the most recent investors.
College Daily articles about Yale have been linked to Chinese state propaganda by the Yale Daily News.
History
CollegeDaily.cn is a Beijing-based news and information platform targeting international Chinese students as well as international college and university faculty and Student Affairs professionals.
Founded in 2014, CollegeDailyCN has grown to cover most of international students studying in North America. Every day, over 500,000 reader get useful information from its multiple platforms. It also has a team of student journalists and editors who provide useful articles and researches to the readers.
The College Daily has spread misleading and false information about the 2019 Hong Kong Protests including that protesters would receive a $20 million reward for killing a police officer. The Diplomat described their efforts to spread misleading information as “notorious."
In September 2019 the College Daily published a story calling for Australian journalist and academic Vicky Xiuzhong Xu’s estranged father to be expelled from China due to her outspoken journalism. The article asserted that Xu was an “American mouthpiece” and that she only criticized the Chinese government in order to get political asylum in Australia.
See also
Chinese Students and Scholars Association
References
New media
Mass media companies of China
Mass media companies of the United States | College Daily | Technology | 432 |
31,377,324 | https://en.wikipedia.org/wiki/Social%20information%20architecture | Social information architecture, also known as social iA, is a sub-domain of information architecture which deals with the social aspects of conceptualizing, modeling and organizing information. It has become more relevant because of the rise of social media and Web 2.0 in recent times.
Approach
There are different approaches to the explanation of social information architecture.
Architecture model (internal space)
Architects designing a physical community space, have to consider how the architecture will shape social interactions. A long hallway of offices creates an utterly different dynamic than desks with arranged in an open space. One might foster individuality, privacy, propriety; the other: collaboration, distraction, communalism.
Still, physical spaces can be flexibly repurposed and worked around if the inhabitants desire a social dynamic not instantly afforded by the space. Office doors can be left open to invite easier interaction. Partitions can be raised between adjacent desks to limit distraction and increase privacy.
That's physical architecture. The information architectures of online communities are far more deterministic and far less flexible. They literally define the social architecture by pre-specifying in immutable computer code what information you have access to, who you can talk to, where you can go. In the online world, information architecture = social architecture.
Social dialogue and information model (external space)
All major brands use information architecture to market their products online, it is then commonly wrapped under the umbrella phrase 'digital strategy'. Information architecture used for strategic purposes encompasses brand SEO, strategic placement of virals, social media presence etc.
Charities, news outlets and social dialogue forums can make a much more specific use of the same tools for positive and important social purposes. Social Information Architecture is perceived as the socially conscious wing of commercial information architecture and function to exchange information and ideas between people and groups.
Social iA can pick up on conflicting issues that are treated with misunderstanding between cultures and leaves individuals and societies vulnerable to exploitation and manipulation. Since the net has such a far reach it is obvious to use it for meaningful and coordinated social dialogue.
Example of such issues are faith, environment, politics, climate change, war, injustice and other social challenges. Information architecture can help create frameworks in which sharing information brings people together, inspires and encourages them to participate in a forward thinking and unfragmented way. One of its core activities is to spread messages that bring people from opposite sites of social and cultural spectrums together and to confront uncomfortable subject head on.
How does social information architecture work?
Social iA utilizes a variety of Web2.0 applications to filter relevant or valuable information and weave them in appropriate information repository or provide feedback to interesting channels. Social iA makes strategic use of Search Engines, Social Media, Google Algorithms, as well as websites, video & news channels. It ‘reads’ or 'listens' to social conversations and search engine queries and engages with the net actively to gather clues about the world's pulse on the internet. It assesses data, social & political trends, and respond with targeted campaigns to give people ideas, as well as help people with making sense of information.
Principals
Dan Brown in his paper 8 Principals of Social Information Architecture enlists the following principals:
1. The principle of objects: Treat content as a living, breathing thing,
with a lifecycle, behaviors and attributes.
2. The principle of choices: Create pages that offer meaningful choices to users, keeping the range of choices available focused on a particular task.
3. The principle of disclosure: Show only enough information to help
people understand what kinds of information they'll find as they dig
deeper.
4. The principle of exemplars: Describe the contents of categories by
showing examples of the contents.
5. The principle of front doors: Assume at least half of the website's
visitors will come through some page other than the home page.
6. The principle of multiple classification: Offer users several different classification schemes to browse the site's content.
7. The principle of focused navigation: Don't mix apples and oranges
in your navigation scheme.
8. The principle of growth: Assume the content you have today is a
small fraction of the content you will have tomorrow.
What can social information architecture achieve?
Social information architecture has many potentials in terms of fostering social connections and how information is shared in social spaces on the web.
References
See also
Wodtke, Christina and Govella, Austin Information Architecture: Blueprints for the Web (2009) Second Edition, Published by New Riders
Information architecture
Data management
Information science
Information technology
Digital technology
New media
Semantic Web | Social information architecture | Technology | 927 |
11,127,829 | https://en.wikipedia.org/wiki/Gibberella%20xylarioides | Gibberella xylarioides (Fusarium xylarioides) is a species of fungus in the family Nectriaceae. It is the causative agent of coffee wilt disease (CWD). The disease caused a severe problem in several countries in West and East Africa during the 1940s and 1950s. CWD was first seen in Coffea liberica.
Hosts
Main hosts
Coffea arabica (arabica coffee)
Coffea canephora (robusta coffee)
Coffea liberica (Liberian coffee tree)
Other hosts
Gossypium (cotton)
Musa × paradisiaca (plantain)
Signs and symptoms
Similar to other vascular wilt pathogens, the fungus colonizes the xylem and causes the flow of water to be cut off. It can be diagnosed by several visual signs. The leaves can wilt, have vein necrosis, and abscission. The coffee bark, when scraped with a knife, will have a blue-black coloration. The berries will appear as though they are ripening prematurely but will stay on the coffee plant after the leaves have fallen off. Necrosis can often be seen near the collar of the plant.
Young trees can be killed within a few days of infection while more mature coffee plants can survive up to 8 months.
Gibberella xylarioides (Sexual form) will make purple perithecia and ascospores, but resting structures are rarely found in the soil. Fusarium xylarioides (Asexual form) make sickle shaped conidia and are spread by wind, rain, and human activities like weeding and harvesting.
Management
Other methods of management include:
Removal of diseased trees and burning is the most successful method of eradication of Coffee Wilt. Coffea sp. should not be replanted in soil for six months to avoid infection of seedlings.
Care when weeding around coffee plants to avoid injuring the bark as the fungus can enter the bark through wounds
Using planting tools that are free of disease
Spraying the soil surface with 2.5% copper (II) sulphate
Breeding resistance—"The results of greenhouse inoculation experiments proved that there was important diversity in coffee populations (within and among the forest sites) in reaction to G. xylariodies infection."
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
xylarioides
Fungi described in 1948
Fungus species | Gibberella xylarioides | Biology | 503 |
14,942,693 | https://en.wikipedia.org/wiki/RAP6 | RAP6 is the abbreviation for Rab5-activating protein 6, a novel endosomal protein with a role in endocytosis. RAP6 was discovered by Alejandro Barbieri and his group of researchers (Christine Hunker, Adriana Galvis, Ivan Kruk, Hugo Giambini, Lina Torres and Maria Luisa Veisaga) working at Florida International University.
This novel human protein has been reported to be involved in membrane trafficking. It has been shown that RAP6 has a guanine nucleotide exchange factor (GEF) activity specific to Rab5 and a GTPase activating protein (GAP) activity specific to RAS.
The original GeneBank Identifications (GIs) have been published in the NCBI Nucleotide databases with GIs 77176718 and 77176720. Since then, many names have been coined to the validated protein such as RabGEF1, GeneID: 27342. RAP6 belongs to the family of the GAPVD1, GeneID: 26130
References
Cellular processes
Transport proteins | RAP6 | Biology | 222 |
2,879,803 | https://en.wikipedia.org/wiki/Zeta%20Arietis | Zeta Arietis, Latinized from ζ Arietis, is a star in the northern constellation of Aries. It is dimly visible to the naked eye with an apparent visual magnitude of +4.89. Based upon an annual parallax shift of 12.77 mas, the distance to this star is . This is an A-type main sequence star with a stellar classification of A1 V. It has a high rate of rotation with a projected rotational velocity of 133 km/s. The star is shining at an effective temperature of 9,500 K, giving it the characteristic white-hued glow of an A-type star.
Name
This star, along with δ Ari, ε Ari, π Ari, and ρ3 Ari, were Al Bīrūnī's Al Buṭain (ألبطين), the dual of Al Baṭn, the Belly. According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Buṭain were the title for five stars : δ Ari as Botein, π Ari as Al Buṭain I, ρ3 Ari as Al Buṭain II, ε Ari as Al Buṭain III dan ζ Ari as Al Buṭain IV.
In Chinese, (), meaning Yin Force, refers to an asterism consisting of ζ Arietis, 63 Arietis, δ Arietis, τ Arietis and 65 Arietis. Consequently, the Chinese name for ζ Arietis itself is (, .)
References
A-type main-sequence stars
Aries (constellation)
Arietis, Zeta
Durchmusterung objects
Arietis, 58
020150
015110
0972 | Zeta Arietis | Astronomy | 351 |
141,163 | https://en.wikipedia.org/wiki/Subnormal%20number | In computer science, subnormal numbers are the subset of denormalized numbers (sometimes called denormals) that fill the underflow gap around zero in floating-point arithmetic. Any non-zero number with magnitude smaller than the smallest positive normal number is subnormal, while denormal can also refer to numbers outside that range.
Terminology
In some older documents (especially standards documents such as the initial releases of IEEE 754 and the C language), "denormal" is used to refer exclusively to subnormal numbers. This usage persists in various standards documents, especially when discussing hardware that is incapable of representing any other denormalized numbers, but the discussion here uses the term "subnormal" in line with the 2008 revision of IEEE 754. In casual discussions the terms subnormal and denormal are often used interchangeably, in part because there are no denormalized IEEE binary numbers outside the subnormal range.
The term "number" is used rather loosely, to describe a particular sequence of digits, rather than a mathematical abstraction; see Floating-point arithmetic for details of how real numbers relate to floating-point representations. "Representation" rather than "number" may be used when clarity is required.
Definition
Mathematical real numbers may be approximated by multiple floating-point representations. One representation is defined as normal, and others are defined as subnormal, denormal, or unnormal by their relationship to normal.
In a normal floating-point value, there are no leading zeros in the significand (also commonly called mantissa); rather, leading zeros are removed by adjusting the exponent (for example, the number 0.0123 would be written as ). Conversely, a denormalized floating-point value has a significand with a leading digit of zero. Of these, the subnormal numbers represent values which if normalized would have exponents below the smallest representable exponent (the exponent having a limited range).
The significand (or mantissa) of an IEEE floating-point number is the part of a floating-point number that represents the significant digits. For a positive normalised number, it can be represented as m0.m1m2m3...mp−2mp−1 (where m represents a significant digit, and p is the precision) with non-zero m0. Notice that for a binary radix, the leading binary digit is always 1. In a subnormal number, since the exponent is the least that it can be, zero is the leading significant digit (0.m1m2m3...mp−2mp−1), allowing the representation of numbers closer to zero than the smallest normal number. A floating-point number may be recognized as subnormal whenever its exponent has the least possible value.
By filling the underflow gap like this, significant digits are lost, but not as abruptly as when using the flush to zero on underflow approach (discarding all significant digits when underflow is reached). Hence the production of a subnormal number is sometimes called gradual underflow because it allows a calculation to lose precision slowly when the result is small.
In IEEE 754-2008, denormal numbers are renamed subnormal numbers and are supported in both binary and decimal formats. In binary interchange formats, subnormal numbers are encoded with a biased exponent of 0, but are interpreted with the value of the smallest allowed exponent, which is one greater (i.e., as if it were encoded as a 1). In decimal interchange formats they require no special encoding because the format supports unnormalized numbers directly.
Mathematically speaking, the normalized floating-point numbers of a given sign are roughly logarithmically spaced, and as such any finite-sized normal float cannot include zero. The subnormal floats are a linearly spaced set of values, which span the gap between the negative and positive normal floats.
Background
Subnormal numbers provide the guarantee that addition and subtraction of floating-point numbers never underflows; two nearby floating-point numbers always have a representable non-zero difference. Without gradual underflow, the subtraction a − b can underflow and produce zero even though the values are not equal. This can, in turn, lead to division by zero errors that cannot occur when gradual underflow is used.
Subnormal numbers were implemented in the Intel 8087 while the IEEE 754 standard was being written. They were by far the most controversial feature in the K-C-S format proposal that was eventually adopted, but this implementation demonstrated that subnormal numbers could be supported in a practical implementation. Some implementations of floating-point units do not directly support subnormal numbers in hardware, but rather trap to some kind of software support. While this may be transparent to the user, it can result in calculations that produce or consume subnormal numbers being much slower than similar calculations on normal numbers.
IEEE
In IEEE binary floating-point formats, subnormals are represented by having a zero exponent field with a non-zero significand field.
No other denormalized numbers exist in the IEEE binary floating-point formats, but they do exist in some other formats, including the IEEE decimal floating-point formats.
Performance issues
Some systems handle subnormal values in hardware, in the same way as normal values. Others leave the handling of subnormal values to system software ("assist"), only handling normal values and zero in hardware. Handling subnormal values in software always leads to a significant decrease in performance. When subnormal values are entirely computed in hardware, implementation techniques exist to allow their processing at speeds comparable to normal numbers. However, the speed of computation remains significantly reduced on many modern x86 processors; in extreme cases, instructions involving subnormal operands may take as many as 100 additional clock cycles, causing the fastest instructions to run as much as six times slower.
This speed difference can be a security risk. Researchers showed that it provides a timing side channel that allows a malicious web site to extract page content from another site inside a web browser.
Some applications need to contain code to avoid subnormal numbers, either to maintain accuracy, or in order to avoid the performance penalty in some processors. For instance, in audio processing applications, subnormal values usually represent a signal so quiet that it is out of the human hearing range. Because of this, a common measure to avoid subnormals on processors where there would be a performance penalty is to cut the signal to zero once it reaches subnormal levels or mix in an extremely quiet noise signal. Other methods of preventing subnormal numbers include adding a DC offset, quantizing numbers, adding a Nyquist signal, etc. Since the SSE2 processor extension, Intel has provided such a functionality in CPU hardware, which rounds subnormal numbers to zero.
Disabling subnormal floats at the code level
Intel SSE
Intel's C and Fortran compilers enable the (denormals-are-zero) and (flush-to-zero) flags for SSE by default for optimization levels higher than . The effect of is to treat subnormal input arguments to floating-point operations as zero, and the effect of is to return zero instead of a subnormal float for operations that would result in a subnormal float, even if the input arguments are not themselves subnormal. clang and gcc have varying default states depending on platform and optimization level.
A non-C99-compliant method of enabling the and flags on targets supporting SSE is given below, but is not widely supported. It is known to work on Mac OS X since at least 2006.
#include <fenv.h>
#pragma STDC FENV_ACCESS ON
// Sets DAZ and FTZ, clobbering other CSR settings.
// See https://opensource.apple.com/source/Libm/Libm-287.1/Source/Intel/, fenv.c and fenv.h.
fesetenv(FE_DFL_DISABLE_SSE_DENORMS_ENV);
// fesetenv(FE_DFL_ENV) // Disable both, clobbering other CSR settings.
For other x86-SSE platforms where the C library has not yet implemented this flag, the following may work:
#include <xmmintrin.h>
_mm_setcsr(_mm_getcsr() | 0x0040); // DAZ
_mm_setcsr(_mm_getcsr() | 0x8000); // FTZ
_mm_setcsr(_mm_getcsr() | 0x8040); // Both
_mm_setcsr(_mm_getcsr() & ~0x8040); // Disable both
The and macros wrap a more readable interface for the code above.
// To enable DAZ
#include <pmmintrin.h>
_MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);
// To enable FTZ
#include <xmmintrin.h>
_MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
Most compilers will already provide the previous macro by default, otherwise the following code snippet can be used (the definition for FTZ is analogous):
#define _MM_DENORMALS_ZERO_MASK 0x0040
#define _MM_DENORMALS_ZERO_ON 0x0040
#define _MM_DENORMALS_ZERO_OFF 0x0000
#define _MM_SET_DENORMALS_ZERO_MODE(mode) _mm_setcsr((_mm_getcsr() & ~_MM_DENORMALS_ZERO_MASK) | (mode))
#define _MM_GET_DENORMALS_ZERO_MODE() (_mm_getcsr() & _MM_DENORMALS_ZERO_MASK)
The default denormalization behavior is mandated by the ABI, and therefore well-behaved software should save and restore the denormalization mode before returning to the caller or calling code in other libraries.
ARM
AArch32 NEON (SIMD) FPU always uses a flush-to-zero mode, which is the same as . For the scalar FPU and in the AArch64 SIMD, the flush-to-zero behavior is optional and controlled by the bit of the control register – FPSCR in Arm32 and FPCR in AArch64.
One way to do this can be:
#if defined(__arm64__) || defined(__aarch64__)
uint64_t fpcr;
asm( "mrs %0, fpcr" : "=r"( fpcr )); //Load the FPCR register
asm( "msr fpcr, %0" :: "r"( fpcr | (1 << 24) )); //Set the 24th bit (FTZ) to 1
#endif
Some ARM processors have hardware handling of subnormals.
See also
Logarithmic number system
Notes
References
Further reading
See also various papers on William Kahan's web site for examples of where subnormal numbers help improve the results of calculations.
Computer arithmetic
Articles with example C code | Subnormal number | Mathematics | 2,445 |
2,072,213 | https://en.wikipedia.org/wiki/Human%20Genetic%20Diversity%3A%20Lewontin%27s%20Fallacy | "Human Genetic Diversity: Lewontin's Fallacy" is a 2003 paper by A. W. F. Edwards in the journal BioEssays. He criticises an argument first made in Richard Lewontin's 1972 article "The Apportionment of Human Diversity", that the practice of dividing humanity into races is taxonomically invalid because any given individual will often have more in common genetically with members of other population groups than with members of their own. Edwards argued that this does not refute the biological reality of race since genetic analysis can usually make correct inferences about the perceived race of a person from whom a sample is taken, and that the rate of success increases when more genetic loci are examined.
Edwards' paper was reprinted, commented upon by experts such as Noah Rosenberg, and given further context in an interview with philosopher of science Rasmus Grønfeldt Winther in a 2018 anthology. Edwards' critique is discussed in a number of academic and popular science books, with varying degrees of support.
Some scholars, including Winther and Jonathan Marks, dispute the premise of "Lewontin's fallacy", arguing that Edwards' critique does not actually contradict Lewontin's argument. A 2007 paper in Genetics by David J. Witherspoon et al. concluded that the two arguments are in fact compatible, and that Lewontin's observation about the distribution of genetic differences across ancestral population groups applies "even when the most distinct populations are considered and hundreds of loci are used".
Lewontin's argument
In the 1972 study "The Apportionment of Human Diversity", Richard Lewontin performed a fixation index (FST) statistical analysis using 17 markers, including blood group proteins, from individuals across classically defined "races" (Caucasian, African, Mongoloid, South Asian Aborigines, Amerinds, Oceanians, and Australian Aborigines). He found that the majority of the total genetic variation between humans (i.e., of the 0.1% of DNA that varies between individuals), 85.4%, is found within populations, 8.3% of the variation is found between populations within a "race", and only 6.3% was found to account for the racial classification. Numerous later studies have confirmed his findings. Based on this analysis, Lewontin concluded, "Since such racial classification is now seen to be of virtually no genetic or taxonomic significance either, no justification can be offered for its continuance."
This argument has been cited as evidence that racial categories are biologically meaningless, and that behavioral differences between groups are not caused by genetic differences. One example is the "Statement on 'Race'" published by the American Anthropological Association in 1998, which rejected the existence of races as unambiguous, clearly demarcated, biologically distinct groups.
Edwards' critique
Edwards argued that while Lewontin's statements on variability are correct when examining the frequency of different alleles (variants of a particular gene) at an individual locus (the location of a particular gene) between individuals, it is nonetheless possible to classify individuals into different racial groups with an accuracy that approaches 100 percent when one takes into account the frequency of the alleles at several loci at the same time. This happens because differences in the frequency of alleles at different loci are correlated across populations—the alleles that are more frequent in a population at two or more loci are correlated when we consider the two populations simultaneously. Or in other words, the frequency of the alleles tends to cluster differently for different populations.
In Edwards' words, "most of the information that distinguishes populations is hidden in the correlation structure of the data". These relationships can be extracted using commonly used ordination and cluster analysis techniques. Edwards argued that, even if the probability of misclassifying an individual based on the frequency of alleles at a single locus is as high as 30% (as Lewontin reported in 1972), the misclassification probability becomes close to zero if enough loci are studied.
Edwards' paper stated that the underlying logic was discussed in the early years of the 20th century. Edwards wrote that he and Luigi Luca Cavalli-Sforza had presented a contrasting analysis to Lewontin's, using very similar data, already at the 1963 International Congress of Genetics. Lewontin participated in the conference but did not refer to this in his later paper. Edwards argued that Lewontin used his analysis to attack human classification in science for social reasons.
Support and criticism
Evolutionary biologist Richard Dawkins discusses genetic variation across human races in his book The Ancestor's Tale. In the chapter "The Grasshopper's Tale", he characterizes the genetic variation between races as a very small fraction of the total human genetic variation, but he disagrees with Lewontin's conclusions about taxonomy, writing: "However small the racial partition of the total variation may be, if such racial characteristics as there are highly correlate with other racial characteristics, they are by definition informative, and therefore of taxonomic significance." Neven Sesardić has argued that, unbeknownst to Edwards, Jeffry B. Mitton had already made the same argument about Lewontin's claim in two articles published in The American Naturalist in the late 1970s.
Biological anthropologist Jonathan M. Marks agrees with Edwards that correlations between geographical areas and genetics obviously exist in human populations but goes on to write: What is unclear is what this has to do with 'race' as that term has been used through much in the twentieth century—the mere fact that we can find groups to be different and can reliably allot people to them is trivial. Again, the point of the theory of race was to discover large clusters of people that are principally homogeneous within and heterogeneous between, contrasting groups. Lewontin's analysis shows that such groups do not exist in the human species, and Edwards' critique does not contradict that interpretation. The view that while geographic clustering of biological traits does exist, this does not lend biological validity to racial groups, was proposed by several evolutionary anthropologists and geneticists prior to the publication of Edwards' critique of Lewontin.
In the 2007 paper "Genetic Similarities Within and Between Human Populations", Witherspoon et al. attempt to answer the question "How often is a pair of individuals from one population genetically more dissimilar than two individuals chosen from two different populations?" The answer depends on the number of polymorphisms used to define that dissimilarity, and the populations being compared. When they analysed three geographically distinct populations (European, African, and East Asian) and measured genetic similarity over many thousands of loci, the answer to their question was "never"; however, measuring similarity using smaller numbers of loci yielded substantial overlap between these populations. Rates of between-population similarity also increased when geographically intermediate and admixed populations were included in the analysis.
Witherspoon et al. write: Since an individual's geographic ancestry can often be inferred from his or her genetic makeup, knowledge of one's population of origin should allow some inferences about individual genotypes. To the extent that phenotypically important genetic variation resembles the variation studied here, we may extrapolate from genotypic to phenotypic patterns. ... However, the typical frequencies of alleles responsible for common complex diseases remain unknown. The fact that, given enough genetic data, individuals can be correctly assigned to their populations of origin is compatible with the observation that most human genetic variation is found within populations, not between them. It is also compatible with our finding that, even when the most distinct populations are considered and hundreds of loci are used, individuals are frequently more similar to members of other populations than to members of their own population. Thus, caution should be used when using geographic or genetic ancestry to make inferences about individual phenotypes. Witherspoon et al. add: "A final complication arises when racial classifications are used as proxies for geographic ancestry. Although many concepts of race are correlated with geographic ancestry, the two are not interchangeable, and relying on racial classifications will reduce predictive power still further."
In a 2014 paper, Rasmus Grønfeldt Winther argues that "Lewontin's fallacy" is effectively a misnomer, as there really are two different sets of methods and questions at play in studying the genomic population structure of our species: "variance partitioning" and "clustering analysis". According to Winther, they are "two sides of the same mathematics coin" and neither "necessarily implies anything about the reality of human groups".
See also
Race and genetics
Population groups in biomedicine
References
Biology papers
Human population genetics
Race (human categorization)
Biology controversies
Taxonomy (biology)
2003 in biology
2003 works
Criticism of individuals | Human Genetic Diversity: Lewontin's Fallacy | Biology | 1,835 |
79,099 | https://en.wikipedia.org/wiki/Maple%20%28software%29 | Maple is a symbolic and numeric computing environment as well as a multi-paradigm programming language. It covers several areas of technical computing, such as symbolic mathematics, numerical analysis, data processing, visualization, and others. A toolbox, MapleSim, adds functionality for multidomain physical modeling and code generation.
Maple's capacity for symbolic computing include those of a general-purpose computer algebra system. For instance, it can manipulate mathematical expressions and find symbolic solutions to
certain problems, such as those arising from ordinary and partial differential equations.
Maple is developed commercially by the Canadian software company Maplesoft. The name 'Maple' is a reference to the software's Canadian heritage.
Overview
Core functionality
Users can enter mathematics in traditional mathematical notation. Custom user interfaces can also be created. There is support for numeric computations, to arbitrary precision, as well as symbolic computation and visualization. Examples of symbolic computations are given below.
Maple incorporates a dynamically typed imperative-style programming language (resembling Pascal), which permits variables of lexical scope. There are also interfaces to other languages (C, C#, Fortran, Java, MATLAB, and Visual Basic), as well as to Microsoft Excel.
Maple supports MathML 2.0, which is a W3C format for representing and interpreting mathematical expressions, including their display in web pages. There is also functionality for converting expressions from traditional mathematical notation to markup suitable for the typesetting system LaTeX.
Architecture
Maple is based on a small kernel, written in C, which provides the Maple language. Most functionality is provided by libraries, which come from a variety of sources. Most of the libraries are written in the Maple language; these have viewable source code. Many numerical computations are performed by the NAG Numerical Libraries, ATLAS libraries, or GMP libraries.
Different functionality in Maple requires numerical data in different formats. Symbolic expressions are stored in memory as directed acyclic graphs. The standard interface and calculator interface are written in Java.
History
The first concept of Maple arose from a meeting in late 1980 at the University of Waterloo. Researchers at the university wished to purchase a computer powerful enough to run the Lisp-based computer algebra system Macsyma. Instead, they opted to develop their own computer algebra system, named Maple, that would run on lower cost computers. Aiming for portability, they began writing Maple in programming languages from the BCPL family (initially using a subset of B and C, and later on only C). A first limited version appeared after three weeks, and fuller versions entered mainstream use beginning in 1982. By the end of 1983, over 50 universities had copies of Maple installed on their machines.
In 1984, the research group arranged with Watcom Products Inc to license and distribute the first commercially available version, Maple 3.3. In 1988 Waterloo Maple Inc. (Maplesoft) was founded. The company's original goal was to manage the distribution of the software, but eventually it grew to have its own R&D department, where most of Maple's development takes place today (the remainder being done at various university laboratories).
In 1989, the first graphical user interface for Maple was developed and included with version 4.3 for the Macintosh. X11 and Windows versions of the new interface followed in 1990 with Maple V. In 1992, Maple V Release 2 introduced the Maple "worksheet" that combined text, graphics, and input and typeset output. In 1994 a special issue of a newsletter created by Maple developers called MapleTech was published.
In 1999, with the release of Maple 6, Maple included some of the NAG Numerical Libraries. In 2003, the current "standard" interface was introduced with Maple 9. This interface is primarily written in Java (although portions, such as the rules for typesetting mathematical formulae, are written in the Maple language). The Java interface was criticized for being slow; improvements have been made in later versions, although the Maple 11 documentation recommends the previous ("classic") interface for users with less than 500 MB of physical memory.
Between 1995 and 2005 Maple lost significant market share to competitors due to a weaker user interface. With Maple 10 in 2005, Maple introduced a new "document mode" interface, which has since been further developed across several releases.
In September 2009 Maple and Maplesoft were acquired by the Japanese software retailer Cybernet Systems.
Version history
Maple 1.0: January, 1982
Maple 1.1: January, 1982
Maple 2.0: May, 1982
Maple 2.1: June, 1982
Maple 2.15: August, 1982
Maple 2.2: December, 1982
Maple 3.0: May, 1983
Maple 3.1: October, 1983
Maple 3.2: April, 1984
Maple 3.3: March, 1985 (first public available version)
Maple 4.0: April, 1986
Maple 4.1: May, 1987
Maple 4.2: December, 1987
Maple 4.3: March, 1989
Maple V: August, 1990
Maple V R2: November 1992
Maple V R3: March 15, 1994
Maple V R4: January, 1996
Maple V R5: November 1, 1997
Maple 6: December 6, 1999
Maple 7: July 1, 2001
Maple 8: April 16, 2002
Maple 9: June 30, 2003
Maple 9.5: April 15, 2004
Maple 10: May 10, 2005
Maple 11: February 21, 2007
Maple 11.01: July, 2007
Maple 11.02: November, 2007
Maple 12: May, 2008
Maple 12.01: October, 2008
Maple 12.02: December, 2008
Maple 13: April 28, 2009
Maple 13.01: July, 2009
Maple 13.02: October, 2009
Maple 14: April 29, 2010
Maple 14.01: October 28, 2010
Maple 15: April 13, 2011
Maple 15.01: June 21, 2011
Maple 16: March 28, 2012
Maple 16.01: May 16, 2012
Maple 17: March 13, 2013
Maple 17.01: July, 2013
Maple 18: Mar 5, 2014
Maple 18.01: May, 2014
Maple 18.01a: July, 2014
Maple 18.02: Nov, 2014
Maple 2015.0: Mar 4, 2015
Maple 2015.1: Nov, 2015
Maple 2016.0: March 2, 2016
Maple 2016.1: April 20, 2016
Maple 2016.1a: April 27, 2016
Maple 2017.0: May 25, 2017
Maple 2017.1: June 28, 2017
Maple 2017.2: August 2, 2017
Maple 2017.3: October 3, 2017
Maple 2018.0: March 21, 2018
Maple 2019.0: March 14, 2019
Maple 2020.0: March 12, 2020
Maple 2021.0: March 10, 2021
Maple 2022.0: March 15, 2022
Maple 2023.0: March 9, 2023
Features
Features of Maple include:
Support for symbolic and numeric computation with arbitrary precision
Elementary and special mathematical function libraries
Complex numbers and interval arithmetic
Arithmetic, greatest common divisors and factorization for multivariate polynomials over the rationals, finite fields, algebraic number fields, and algebraic function fields
Limits, series and asymptotic expansions
Gröbner basis
Differential Algebra
Matrix manipulation tools including support for sparse arrays
Mathematical function graphing and animation tools
Solvers for systems of equations, diophantine equations, ODEs, PDEs, DAEs, DDEs and recurrence relations
Numeric and symbolic tools for discrete and continuous calculus including definite and indefinite integration, definite and indefinite summation, automatic differentiation and continuous and discrete integral transforms
Constrained and unconstrained local and global optimization
Statistics including model fitting, hypothesis testing, and probability distributions
Tools for data manipulation, visualization and analysis
Tools for probability and combinatoric problems
Support for time-series and unit based data
Connection to online collection of financial and economic data
Tools for financial calculations including bonds, annuities, derivatives, options etc.
Calculations and simulations on random processes
Tools for text mining including regular expressions
Tools for signal processing and linear and non-linear control systems
Discrete math tools including number theory
Tools for visualizing and analysing directed and undirected graphs
Group theory including permutation and finitely presented groups
Symbolic tensor functions
Import and export filters for data, image, sound, CAD, and document formats
Technical word processing including formula editing
Programming language supporting procedural, functional and object-oriented constructs
Tools for adding user interfaces to calculations and applications
Tools for connecting to SQL, Java, .NET, C++, Fortran and http
Tools for generating code for C, C#, Fortran, Java, JavaScript, Julia, Matlab, Perl, Python, R, and Visual Basic
Tools for parallel programming
Examples of Maple code
The following code, which computes the factorial of a nonnegative integer, is an example of an imperative programming construct within Maple:
myfac := proc(n::nonnegint)
local out, i;
out := 1;
for i from 2 to n do
out := out * i
end do;
out
end proc;
Simple functions can also be defined using the "maps to" arrow notation:
myfac := n -> product(i, i = 1..n);
Integration
Find
.
int(cos(x/a), x);
Output:
Determinant
Compute the determinant of a matrix.
M := Matrix([[1,2,3], [a,b,c], [x,y,z]]); # example Matrix
LinearAlgebra:-Determinant(M);
Series expansion
series(tanh(x), x = 0, 15)
Solve equations numerically
The following code numerically calculates the roots of a high-order polynomial:
f := x^53-88*x^5-3*x-5 = 0
fsolve(f)
-1.097486315, -.5226535640, 1.099074017
The same command can also solve systems of equations:
f := (cos(x+y))^2 + exp(x)*y+cot(x-y)+cosh(z+x) = 0:
g := x^5 - 8*y = 2:
h := x+3*y-77*z=55;
fsolve( {f,g,h} );
{x = -2.080507182, y = -5.122547821, z = -0.9408850733}
Plotting of function of single variable
Plot with ranging from -10 to 10:
plot(x*sin(x), x = -10..10);
Plotting of function of two variables
Plot with and ranging from -1 to 1:
plot3d(x^2+y^2, x = -1..1, y = -1..1);
Animation of functions
Animation of function of two variables
plots:-animate(subs(k = 0.5, f), x=-30..30, t=-10..10, numpoints=200, frames=50, color=red, thickness=3);
Animation of functions of three variables
plots:-animate3d(cos(t*x)*sin(3*t*y), x=-Pi..Pi, y=-Pi..Pi, t=1..2);
Fly-through animation of 3-D plots.
M := Matrix([[400,400,200], [100,100,-400], [1,1,1]], datatype=float[8]):
plot3d(1, x=0..2*Pi, y=0..Pi, axes=none, coords=spherical, viewpoint=[path=M]);
Laplace transform
Laplace transform
f := (1+A*t+B*t^2)*exp(c*t);
inttrans:-laplace(f, t, s);
inverse Laplace transform
inttrans:-invlaplace(1/(s-a), s, x);
Fourier transform
Fourier transform
inttrans:-fourier(sin(x), x, w)
Integral equations
Find functions that satisfy the integral equation
.
eqn:= f(x)-3*Int((x*y+x^2*y^2)*f(y), y=-1..1) = h(x):
intsolve(eqn,f(x));
Use of the Maple engine
The Maple engine is used within several other products from Maplesoft:
MapleNet allows users to create JSP pages and Java Applets. MapleNet 12 and above also allow users to upload and work with Maple worksheets containing interactive components.
MapleSim, an engineering simulation tool.
Maple Quantum Chemistry Package from RDMChem computes and visualizes the electronic energies and properties of molecules.
Listed below are third-party commercial products that no longer use the Maple engine:
Versions of Mathcad released between 1994 and 2006 included a Maple-derived algebra engine (MKM, aka Mathsoft Kernel Maple), though subsequent versions use MuPAD.
Symbolic Math Toolbox in MATLAB contained a portion of the Maple 10 engine, but now uses MuPAD (starting with MATLAB R2007b+ release).
Older versions of the mathematical editor Scientific Workplace included Maple as a computational engine, though current versions include MuPAD.
See also
Comparison of computer algebra systems
Comparison of numerical-analysis software
Comparison of programming languages
Comparison of statistical packages
List of computer algebra systems
List of computer simulation software
List of graphing software
List of numerical-analysis software
Mathematical software
SageMath (an open source algebra program)
References
External links
Maplesoft, division of Waterloo Maple, Inc. – official website
C (programming language) software
Notebook interface
Computer algebra system software for Linux
Computer algebra system software for macOS
Computer algebra system software for Windows
Computer algebra systems
Cross-platform software
Data mining and machine learning software
Data and information visualization software
Data-centric programming languages
Econometrics software
Functional languages
Interactive geometry software
IRIX software
Linear algebra
Maplesoft
Mathematical optimization software
Mathematical software
Numerical analysis software for Linux
Numerical analysis software for macOS
Numerical analysis software for Windows
Numerical programming languages
Numerical software
Parallel computing
Physics software
Plotting software
Products introduced in 1982
Proprietary commercial software for Linux
Proprietary cross-platform software
Regression and curve fitting software
Simulation programming languages
Software modeling language
Statistical programming languages
Theorem proving software systems
Time series software | Maple (software) | Physics,Mathematics | 3,036 |
31,698,015 | https://en.wikipedia.org/wiki/Berlekamp%E2%80%93Welch%20algorithm | The Berlekamp–Welch algorithm, also known as the Welch–Berlekamp algorithm, is named for Elwyn R. Berlekamp and Lloyd R. Welch. This is a decoder algorithm that efficiently corrects errors in Reed–Solomon codes for an RS(n, k), code based on the Reed Solomon original view where a message is used as coefficients of a polynomial or used with Lagrange interpolation to generate the polynomial of degree < k for inputs and then is applied to to create an encoded codeword .
The goal of the decoder is to recover the original encoding polynomial , using the known inputs and received codeword with possible errors. It also computes an error polynomial where corresponding to errors in the received codeword.
The key equations
Defining e = number of errors, the key set of n equations is
Where E(ai) = 0 for the e cases when bi ≠ F(ai), and E(ai) ≠ 0 for the n - e non error cases where bi = F(ai) . These equations can't be solved directly, but by defining Q() as the product of E() and F():
and adding the constraint that the most significant coefficient of E(ai) = ee = 1, the result will lead to a set of equations that can be solved with linear algebra.
where q = n - e - 1. Since ee is constrained to be 1, the equations become:
resulting in a set of equations which can be solved using linear algebra, with time complexity .
The algorithm begins assuming the maximum number of errors e = ⌊(n-k)/2⌋. If the equations can not be solved (due to redundancy), e is reduced by 1 and the process repeated, until the equations can be solved or e is reduced to 0, indicating no errors. If Q()/E() has remainder = 0, then F() = Q()/E() and the code word values F(ai) are calculated for the locations where E(ai) = 0 to recover the original code word. If the remainder ≠ 0, then an uncorrectable error has been detected.
Example
Consider RS(7,3) (n = 7, k = 3) defined in with α = 3 and input values: ai = i-1 : {0,1,2,3,4,5,6}. The message to be systematically encoded is {1,6,3}. Using Lagrange interpolation, F(ai) = 3 x2 + 2 x + 1, and applying F(ai) for a4 = 3 to a7 = 6, results in the code word {1,6,3,6,1,2,2}. Assume errors occur at c2 and c5 resulting in the received code word {1,5,3,6,3,2,2}. Start off with e = 2 and solve the linear equations:
Starting from the bottom of the right matrix, and the constraint e2 = 1:
with remainder = 0.
E(ai) = 0 at a2 = 1 and a5 = 4
Calculate F(a2 = 1) = 6 and F(a5 = 4) = 1 to produce corrected code word {1,6,3,6,1,2,2}.
See also
Reed–Solomon error correction
External links
MIT Lecture Notes on Essential Coding Theory – Dr. Madhu Sudan
University at Buffalo Lecture Notes on Coding Theory – Dr. Atri Rudra
Algebraic Codes on Lines, Planes and Curves, An Engineering Approach – Richard E. Blahut
Welch Berlekamp Decoding of Reed–Solomon Codes – L. R. Welch
– The patent by Lloyd R. Welch and Elewyn R. Berlekamp
Finite fields
Coding theory
Information theory
Error detection and correction | Berlekamp–Welch algorithm | Mathematics,Technology,Engineering | 795 |
51,423,025 | https://en.wikipedia.org/wiki/Chirality%20Medal | The Chirality Medal, instituted by the Società Chimica Italiana in 1991 to honor internationally recognized scientists who have made a distinguished contribution to all aspects of chirality, is awarded each year by a Chirality Medal Honor Committee composed of the Chirality International Committee members and the most recent recipients of the Chirality Medal. The medal is awarded to the recipient at the International Conference on Chirality.
List of Past Winners
See also
List of chemistry awards
References
Chemistry awards | Chirality Medal | Technology | 101 |
2,505,273 | https://en.wikipedia.org/wiki/Million%20service%20units | A million service units (MSU) is a measurement of the amount of processing work a computer can perform in one hour. The term is most commonly associated with IBM mainframes. It reflects how IBM rates the machine in terms of charging capacity. The technical measure of processing power on IBM mainframes, however, are Service Units per second (or SU/sec).
One “service unit” originally related to an actual hardware performance measurement (a specific model's instruction performance). However, that relationship disappeared many years ago as hardware and software evolved. MSUs are now like other common (but physically imprecise) measurements, such as “cans of coffee” or “tubes of toothpaste.” (Cans and tubes can vary in physical size depending on brand, market, and other factors. Some coffee cans contain 500 grams and others 13 ounces, for example.)
Most mainframe software vendors use a licensing and pricing model in which the customers are charged per MSU consumed (i.e. the number of operations the software has performed) in addition to hardware and software installation costs. Others charge by total MSU system capacity. Thus, while MSU is an artificial construction, it does have a direct financial implication. In fact, software charges are why the MSU measurement exists at all.
IBM publishes MSU ratings for every mainframe server model, including the zSeries and System z9 ranges. For example, a zSeries z890 Model 110 is a 4 MSU system. MSU ratings are always rounded to whole numbers. IBM enforces an MSU rule called the “technology dividend”: each new mainframe model has a 10% lower MSU rating for the same level of system capacity. For example, when IBM introduced the System z9-109 in 2005, if a particular z9 configuration could process the same number of transactions per second as its predecessor (a particular z990 configuration) then it would do so with 10% fewer MSUs. The lower MSU rating means lower software costs, providing an incentive for customers to upgrade.
However, as software costs are not linear with MSUs, decreasing or increasing MSUs will not show a proportional change in software costs. The "least expensive" MSUs will be added (with increased MSUs) or removed (with decreased MSUs). For example, a 10% increase in MSUs will result in a software cost increase of less than 10%. How much more (or less, if reducing MSUs) depends on numerous other factors.
Sample usage
“Our accounting department will need 6.5 MSUs on a System z9-109 from 10 p.m. to 1:00 a.m. each night in order make sure our quarterly financial statements arrive on time.”
“You will need 8 more Db2 MSUs for your z900 to handle this year’s Christmas sales rush. Since your current z900 configuration doesn’t have enough capacity to add 8 Db2 MSUs, you need to add another engine. It might be less expensive to upgrade to a z9 because of the double technology dividend.”
See also
Instructions per second
z/OS
z/VSE
External links
Sample MSU Figures for various hardware configurations (IBM Website)
References
Computer performance | Million service units | Technology | 671 |
76,653 | https://en.wikipedia.org/wiki/Naval%20architecture | Naval architecture, or naval engineering, is an engineering discipline incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the engineering design process, shipbuilding, maintenance, and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation (classification) and calculations during all stages of the life of a marine vehicle. Preliminary design of the vessel, its detailed design, construction, trials, operation and maintenance, launching and dry-docking are the main activities involved. Ship design calculations are also required for ships being modified (by means of conversion, rebuilding, modernization, or repair). Naval architecture also involves formulation of safety regulations and damage-control rules and the approval and certification of ship designs to meet statutory and non-statutory requirements.
Main subjects
The word "vessel" includes every description of watercraft, mainly ships and boats, but also including non-displacement craft, WIG craft and seaplanes, used or capable of being used as a means of transportation on water. The principal elements of naval architecture are detailed in the following sections.
Hydrostatics
Hydrostatics concerns the conditions to which the vessel is subjected while at rest in water and to its ability to remain afloat. This involves computing buoyancy, displacement, and other hydrostatic properties such as trim (the measure of the longitudinal inclination of the vessel) and stability (the ability of a vessel to restore itself to an upright position after being inclined by wind, sea, or loading conditions).
Hydrodynamics
Hydrodynamics concerns the flow of water around the ship's hull, bow, and stern, and over bodies such as propeller blades or rudder, or through thruster tunnels.
Ship resistance and propulsion concern resistance towards motion in water primarily caused due to flow of water around the hull. Powering calculation is done based on this.
Propulsion is used to move the vessel through water using propellers, thrusters, water jets, sails etc. Engine types are mainly internal combustion. Some vessels are electrically powered using nuclear or solar energy.
Ship motions involves motions of the vessel in seaway and its responses in waves and wind.
Controllability (maneuvering) involves controlling and maintaining position and direction of the vessel.
Flotation and stability
While atop a liquid surface a floating body has 6 degrees of freedom in its movements, these are categorized in either translation or rotation.
Translation
Sway: transverse
Surge: fore and aft
Heave: vertical
Rotation
Yaw: about a vertical axis
Pitch or trim: about a transverse axis
Roll or heel: about a fore and aft axis
Longitudinal stability for longitudinal inclinations, the stability depends upon the distance between the center of gravity and the longitudinal meta-center. In other words, the basis in which the ship maintains its center of gravity is its distance set equally apart from both the aft and forward section of the ship.
While a body floats on a liquid surface it still encounters the force of gravity pushing down on it. In order to stay afloat and avoid sinking there is an opposed force acting against the body known as the hydrostatic pressures. The forces acting on the body must be of the same magnitude and same line of motion in order to maintain the body at equilibrium. This description of equilibrium is only present when a freely floating body is in still water, when other conditions are present the magnitude of which these forces shifts drastically creating the swaying motion of the body.
The buoyancy force is equal to the weight of the body, in other words, the mass of the body is equal to the mass of the water displaced by the body. This adds an upward force to the body by the amount of surface area times the area displaced in order to create an equilibrium between the surface of the body and the surface of the water.
The stability of a ship under most conditions is able to overcome any form or restriction or resistance encountered in rough seas; however, ships have undesirable roll characteristics when the balance of oscillations in roll is two times that of oscillations in heave, thus causing the ship to capsize.
Structures
Structures involves selection of material of construction, structural analysis of global and local strength of the vessel, vibration of the structural components and structural responses of the vessel during motions in seaway. Depending on type of ship, the structure and design will vary in what material to use as well as how much of it. Some ships are made from glass reinforced plastics but the vast majority are steel with possibly some aluminium in the superstructure.
The complete structure of the ship is designed with panels shaped in a rectangular form consisting of steel plating supported on four edges. Combined in a large surface area the Grillages create the hull of the ship, deck, and bulkheads while still providing mutual support of the frames. Though the structure of the ship is sturdy enough to hold itself together the main force it has to overcome is longitudinal bending creating a strain against its hull, its structure must be designed so that the material is disposed as much forward and aft as possible.
The principal longitudinal elements are the deck, shell plating, inner bottom all of which are in the form of grillages, and additional longitudinal stretching to these. The dimensions of the ship are in order to create enough spacing between the stiffeners in prevention of buckling. Warships have used a longitudinal system of stiffening that many modern commercial vessels have adopted. This system was widely used in early merchant ships such as the SS Great Eastern, but later shifted to transversely framed structure another concept in ship hull design that proved more practical. This system was later implemented on modern vessels such as tankers because of its popularity and was then named the Isherwood System.
The arrangement of the Isherwood system consists of stiffening decks both side and bottom by longitudinal members, they are separated enough so they have the same distance between them as the frames and beams. This system works by spacing out the transverse members that support the longitudinal by about 3 or 4 meters, with the wide spacing this causes the traverse strength needed by displacing the amount of force the bulkheads provide.
Arrangements
Arrangements involves concept design, layout and access, fire protection, allocation of spaces, ergonomics and capacity.
Construction
Construction depends on the material used. When steel or aluminium is used this involves welding of the plates and profiles after rolling, marking, cutting and bending as per the structural design drawings or models, followed by erection and launching. Other joining techniques are used for other materials like fibre reinforced plastic and glass-reinforced plastic. The process of construction is thought-out cautiously while considering all factors like safety, strength of structure, hydrodynamics, and ship arrangement. Each factor considered presents a new option for materials to consider as well as ship orientation. When the strength of the structure is considered the acts of ship collision are considered in the way that the ships structure is altered. Therefore, the properties of materials are considered carefully as applied material on the struck ship has elastic properties, the energy absorbed by the ship being struck is then deflected in the opposite direction, so both ships go through the process of rebounding to prevent further damage.
Science and craft
Traditionally, naval architecture has been more craft than science. The suitability of a vessel's shape was judged by looking at a half-model of a vessel or a prototype. Ungainly shapes or abrupt transitions were frowned on as being flawed. This included rigging, deck arrangements, and even fixtures. Subjective descriptors such as ungainly, full, and fine were used as a substitute for the more precise terms used today. A vessel was, and still is described as having a ‘fair’ shape. The term ‘fair’ is meant to denote not only a smooth transition from fore to aft but also a shape that was ‘right.’ Determining what is ‘right’ in a particular situation in the absence of definitive supporting analysis encompasses the art of naval architecture to this day.
Modern low-cost digital computers and dedicated software, combined with extensive research to correlate full-scale, towing tank and computational data, have enabled naval architects to more accurately predict the performance of a marine vehicle. These tools are used for static stability (intact and damaged), dynamic stability, resistance, powering, hull development, structural analysis, green water modelling, and slamming analysis. Data are regularly shared in international conferences sponsored by RINA, Society of Naval Architects and Marine Engineers (SNAME) and others. Computational Fluid Dynamics is being applied to predict the response of a floating body in a random sea.
The naval architect
Due to the complexity associated with operating in a marine environment, naval architecture is a co-operative effort between groups of technically skilled individuals who are specialists in particular fields, often coordinated by a lead naval architect. This inherent complexity also means that the analytical tools available are much less evolved than those for designing aircraft, cars and even spacecraft. This is due primarily to the paucity of data on the environment the marine vehicle is required to work in and the complexity of the interaction of waves and wind on a marine structure.
A naval architect is an engineer who is responsible for the design, classification, survey, construction, and/or repair of ships, boats, other marine vessels, and offshore structures, both commercial and military, including:
Merchant ships – oil tankers, gas tankers, cargo ships, bulk carriers, container ships
Passenger/vehicle ferries, cruise ships
Warships – frigates, destroyers, aircraft carriers, amphibious ships
Submarines and underwater vehicles
Icebreakers
High speed craft – hovercraft, multi-hull ships, hydrofoil craft
Workboats – barges, fishing boats, anchor handling tug supply vessels, platform supply vessels, tug boats, pilot vessels, rescue craft
Yachts, power boats, and other recreational watercraft
Offshore platforms and subsea developments
Some of these vessels are amongst the largest (such as supertankers), most complex (such as aircraft carriers), and highly valued movable structures produced by mankind. They are typically the most efficient method of transporting the world's raw materials and products. Modern engineering on this scale is essentially a team activity conducted by specialists in their respective fields and disciplines.
Naval architects integrate these activities. This demanding leadership role requires managerial qualities and the ability to bring together the often-conflicting demands of the various design constraints to produce a product which is fit for the purpose.
In addition to this leadership role, a naval architect also has a specialist function in ensuring that a safe, economic, environmentally sound and seaworthy design is produced. To undertake all these tasks, a naval architect must have an understanding of many branches of engineering and must be in the forefront of high technology areas. He or she must be able to effectively utilize the services provided by scientists, lawyers, accountants, and business people of many kinds.
Naval architects typically work for shipyards, ship owners, design firms and consultancies, equipment manufacturers, Classification societies, regulatory bodies (Admiralty law), navies, and governments. A small majority of Naval Architects also work in education, of which only 5 universities in the United States are accredited with Naval Architecture & Marine Engineering programs. The United States Naval Academy is home to one of the most knowledgeable professors of Naval Architecture; CAPT. Michael Bito, USN.
See also
References
Further reading
Paasch, H. Dictionary of Naval Terms, from Keel to Truck. London: G. Philip & Son, 1908.
Engineering disciplines
Marine occupations
Shipbuilding
Nautical terminology | Naval architecture | Engineering | 2,312 |
643,854 | https://en.wikipedia.org/wiki/Bourgeois%20nationalism | In Marxist theory, bourgeois nationalism is the ideology of the ruling capitalist class which aims to overcome class antagonism between proletariat and bourgeoisie by appealing to national unity. It is seen as a distraction from engaging in class struggle and an attempt to impose interests of capitalists on the proletariat by constructing capitalist interests as "national interests". Internationally, it aims to create antagonism between workers of different nations and serves as a divide-and-conquer strategy. The bourgeois nationalism is contrasted with left-wing nationalism and proletarian internationalism.
Usage
Soviet Union
After the October Revolution, the Bolshevik government based its nationalities policy (korenization) on the principles of Marxism. According to these principles, all nations should disappear with time, and nationalism was considered a bourgeois ideology. By the mid-1930s these policies were replaced with more extreme assimilationist and Russification policies. The term was used indiscriminately to smear national groups opposed to Russian centralism.
In his Report on the 50th anniversary of the formation of the USSR, Leonid Brezhnev emphasized: "That is why Communists and all fighters for socialism believe that the main aspect of the national question is unification of the working people, regardless of their national origin, in the common battle against every type of oppression, and for a new social system which rules out exploitation of the working people."
In the Soviet Union throughout its existence, the term generally referred to Ukrainian, Estonian, Latvian, Armenian, Kazakh and other types of nationalism that were propagated by the Soviet Union's non-Russian minorities. The Soviet leadership saw their struggle for independence as a threat to the entire existence of the USSR's communist regime.
China
Bourgeois nationalism as a concept was discussed by China's president, Liu Shaoqi as follows:
Jews and Zionism
In 1949, the Communist Party USA declared the Zionist movement to be a form of "Jewish bourgeois nationalism".
Writing for People's World, the leftist activist John Gilman referred to Jewish bourgeoisie nationalism as having multiple varieties, including Jewish assimilationism and Zionism.
See also
Class collaboration
Korenization
Liberal nationalism
Proletarian internationalism (an antonym of bourgeois nationalism)
Russification
Social patriotism
Socialist patriotism
Sovietization
References
Further reading
Internationalism and Nationalism by Liu Shaoqi
Marxism and Nationalism by Tom Lewis
Anti-Zionism
Ideology of the Communist Party of the Soviet Union
Soviet phraseology
Marxist terminology
Political science terminology
Nationalism in the Soviet Union
Nationalism
Anti-nationalism
Diversionary tactics
Conflict (process)
Power (social and political) concepts
Bourgeoisie
Propaganda in the Soviet Union | Bourgeois nationalism | Biology | 527 |
25,418 | https://en.wikipedia.org/wiki/Proof%20by%20contradiction | In logic, proof by contradiction is a form of proof that establishes the truth or the validity of a proposition by showing that assuming the proposition to be false leads to a contradiction.
Although it is quite freely used in mathematical proofs, not every school of mathematical thought accepts this kind of nonconstructive proof as universally valid.
More broadly, proof by contradiction is any form of argument that establishes a statement by arriving at a contradiction, even when the initial assumption is not the negation of the statement to be proved. In this general sense, proof by contradiction is also known as indirect proof, proof by assuming the opposite, and reductio ad impossibile.
A mathematical proof employing proof by contradiction usually proceeds as follows:
The proposition to be proved is P.
We assume P to be false, i.e., we assume ¬P.
It is then shown that ¬P implies falsehood. This is typically accomplished by deriving two mutually contradictory assertions, Q and ¬Q, and appealing to the law of noncontradiction.
Since assuming P to be false leads to a contradiction, it is concluded that P is in fact true.
An important special case is the existence proof by contradiction: in order to demonstrate that an object with a given property exists, we derive a contradiction from the assumption that all objects satisfy the negation of the property.
Formalization
The principle may be formally expressed as the propositional formula ¬¬P ⇒ P, equivalently (¬P ⇒ ⊥) ⇒ P, which reads: "If assuming P to be false implies falsehood, then P is true."
In natural deduction the principle takes the form of the rule of inference
which reads: "If is proved, then may be concluded."
In sequent calculus the principle is expressed by the sequent
which reads: "Hypotheses and entail the conclusion or ."
Justification
In classical logic the principle may be justified by the examination of the truth table of the proposition ¬¬P ⇒ P, which demonstrates it to be a tautology:
Another way to justify the principle is to derive it from the law of the excluded middle, as follows. We assume ¬¬P and seek to prove P. By the law of excluded middle P either holds or it does not:
if P holds, then of course P holds.
if ¬P holds, then we derive falsehood by applying the law of noncontradiction to ¬P and ¬¬P, after which the principle of explosion allows us to conclude P.
In either case, we established P. It turns out that, conversely, proof by contradiction can be used to derive the law of excluded middle.
In classical sequent calculus LK proof by contradiction is derivable from the inference rules for negation:
Relationship with other proof techniques
Refutation by contradiction
Proof by contradiction is similar to refutation by contradiction, also known as proof of negation, which states that ¬P is proved as follows:
The proposition to be proved is ¬P.
Assume P.
Derive falsehood.
Conclude ¬P.
In contrast, proof by contradiction proceeds as follows:
The proposition to be proved is P.
Assume ¬P.
Derive falsehood.
Conclude P.
Formally these are not the same, as refutation by contradiction applies only when the proposition to be proved is negated, whereas proof by contradiction may be applied to any proposition whatsoever. In classical logic, where and may be freely interchanged, the distinction is largely obscured. Thus in mathematical practice, both principles are referred to as "proof by contradiction".
Law of the excluded middle
Proof by contradiction is equivalent to the law of the excluded middle, first formulated by Aristotle, which states that either an assertion or its negation is true, P ∨ ¬P.
Law of non-contradiction
The law of noncontradiction was first stated as a metaphysical principle by Aristotle. It posits that a proposition and its negation cannot both be true, or equivalently, that a proposition cannot be both true and false. Formally the law of non-contradiction is written as ¬(P ∧ ¬P) and read as "it is not the case that a proposition is both true and false". The law of non-contradiction neither follows nor is implied by the principle of Proof by contradiction.
The laws of excluded middle and non-contradiction together mean that exactly one of P and ¬P is true.
Proof by contradiction in intuitionistic logic
In intuitionistic logic proof by contradiction is not generally valid, although some particular instances can be derived. In contrast, proof of negation and principle of noncontradiction are both intuitionistically valid.
Brouwer–Heyting–Kolmogorov interpretation of proof by contradiction gives the following intuitionistic validity condition:
If we take "method" to mean algorithm, then the condition is not acceptable, as it would allow us to solve the Halting problem. To see how, consider the statement H(M) stating "Turing machine M halts or does not halt". Its negation ¬H(M) states that "M neither halts nor does not halt", which is false by the law of noncontradiction (which is intuitionistically valid). If proof by contradiction were intuitionistically valid, we would obtain an algorithm for deciding whether an arbitrary Turing machine M halts, thereby violating the (intuitionistically valid) proof of non-solvability of the Halting problem.
A proposition P which satisfies is known as a ¬¬-stable proposition. Thus in intuitionistic logic proof by contradiction is not universally valid, but can only be applied to the ¬¬-stable propositions. An instance of such a proposition is a decidable one, i.e., satisfying . Indeed, the above proof that the law of excluded middle implies proof by contradiction can be repurposed to show that a decidable proposition is ¬¬-stable. A typical example of a decidable proposition is a statement that can be checked by direct computation, such as " is prime" or " divides ".
Examples of proofs by contradiction
Euclid's Elements
An early occurrence of proof by contradiction can be found in Euclid's Elements, Book 1, Proposition 6:
If in a triangle two angles equal one another, then the sides opposite the equal angles also equal one another.
The proof proceeds by assuming that the opposite sides are not equal, and derives a contradiction.
Hilbert's Nullstellensatz
An influential proof by contradiction was given by David Hilbert. His
Nullstellensatz states:
If are polynomials in indeterminates with complex coefficients, which have no common complex zeros, then there are polynomials such that
Hilbert proved the statement by assuming that there are no such polynomials and derived a contradiction.
Infinitude of primes
Euclid's theorem states that there are infinitely many primes. In Euclid's Elements the theorem is stated in Book IX, Proposition 20:
Prime numbers are more than any assigned multitude of prime numbers.
Depending on how we formally write the above statement, the usual proof takes either the form of a proof by contradiction or a refutation by contradiction. We present here the former, see below how the proof is done as refutation by contradiction.
If we formally express Euclid's theorem as saying that for every natural number there is a prime bigger than it, then we employ proof by contradiction, as follows.
Given any number , we seek to prove that there is a prime larger than . Suppose to the contrary that no such p exists (an application of proof by contradiction). Then all primes are smaller than or equal to , and we may form the list of them all. Let be the product of all primes and . Because is larger than all prime numbers it is not prime, hence it must be divisible by one of them, say . Now both and are divisible by , hence so is their difference , but this cannot be because 1 is not divisible by any primes. Hence we have a contradiction and so there is a prime number bigger than
Examples of refutations by contradiction
The following examples are commonly referred to as proofs by contradiction, but formally employ refutation by contradiction (and therefore are intuitionistically valid).
Infinitude of primes
Let us take a second look at Euclid's theorem – Book IX, Proposition 20:
Prime numbers are more than any assigned multitude of prime numbers.
We may read the statement as saying that for every finite list of primes, there is another prime not on that list,
which is arguably closer to and in the same spirit as Euclid's original formulation. In this case Euclid's proof applies refutation by contradiction at one step, as follows.
Given any finite list of prime numbers , it will be shown that at least one additional prime number not in this list exists. Let be the product of all the listed primes and a prime factor of , possibly itself. We claim that is not in the given list of primes. Suppose to the contrary that it were (an application of refutation by contradiction). Then would divide both and , therefore also their difference, which is . This gives a contradiction, since no prime number divides 1.
Irrationality of the square root of 2
The classic proof that the square root of 2 is irrational is a refutation by contradiction.
Indeed, we set out to prove the negation ¬ ∃ a, b ∈ . a/b = by assuming that there exist natural numbers a and b whose ratio is the square root of two, and derive a contradiction.
Proof by infinite descent
Proof by infinite descent is a method of proof whereby a smallest object with desired property is shown not to exist as follows:
Assume that there is a smallest object with the desired property.
Demonstrate that an even smaller object with the desired property exists, thereby deriving a contradiction.
Such a proof is again a refutation by contradiction. A typical example is the proof of the proposition "there is no smallest positive rational number": assume there is a smallest positive rational number q and derive a contradiction by observing that is even smaller than q and still positive.
Russell's paradox
Russell's paradox, stated set-theoretically as "there is no set whose elements are precisely those sets that do not contain themselves", is a negated statement whose usual proof is a refutation by contradiction.
Notation
Proofs by contradiction sometimes end with the word "Contradiction!". Isaac Barrow and Baermann used the notation Q.E.A., for "quod est absurdum" ("which is absurd"), along the lines of Q.E.D., but this notation is rarely used today. A graphical symbol sometimes used for contradictions is a downwards zigzag arrow "lightning" symbol (U+21AF: ↯), for example in Davey and Priestley. Others sometimes used include a pair of opposing arrows (as or ), struck-out arrows (), a stylized form of hash (such as U+2A33: ⨳), or the "reference mark" (U+203B: ※), or .
Hardy's view
G. H. Hardy described proof by contradiction as "one of a mathematician's finest weapons", saying "It is a far finer gambit than any chess gambit: a chess player may offer the sacrifice of a pawn or even a piece, but a mathematician offers the game."
Automated theorem proving
In automated theorem proving the method of resolution is based on proof by contradiction. That is, in order to show that a given statement is entailed by given hypotheses, the automated prover assumes the hypotheses and the negation of the statement, and attempts to derive a contradiction.
See also
Law of excluded middle
Law of noncontradiction
Proof by exhaustion
Proof by infinite descent
Modus tollens
Reductio ad absurdum
References
Further reading and external links
Proof by Contradiction from Larry W. Cusick's How To Write Proofs
Reductio ad Absurdum Internet Encyclopedia of Philosophy; ISSN 2161-0002
Mathematical proofs
Methods of proof
Theorems in propositional logic | Proof by contradiction | Mathematics | 2,496 |
203,883 | https://en.wikipedia.org/wiki/Interstellar%20communication | Interstellar communication is the transmission of signals between planetary systems. Sending interstellar messages is potentially much easier than interstellar travel, being possible with technologies and equipment which are currently available. However, the distances from Earth to other potentially inhabited systems introduce prohibitive delays, assuming the limitations of the speed of light. Even an immediate reply to radio communications sent to stars tens of thousands of light-years away would take many human generations to arrive.
Radio
The SETI project has for the past several decades been conducting a search for signals being transmitted by extraterrestrial life located outside the Solar System, primarily in the radio frequencies of the electromagnetic spectrum. Special attention has been given to the Water Hole, the frequency of one of neutral hydrogen's absorption lines, due to the low background noise at this frequency and its symbolic association with the basis for what is likely to be the most common system of biochemistry (but see alternative biochemistry).
The regular radio pulses emitted by pulsars were briefly thought to be potential intelligent signals; the first pulsar to be discovered was originally designated "LGM-1", for "Little Green Men." They were quickly determined to be of natural origin, however.
Several attempts have been made to transmit signals to other stars as well. (See "Realized projects" at Active SETI.) One of the earliest and most famous was the 1974 radio message sent from the largest radio telescope in the world, the Arecibo Observatory in Puerto Rico. An extremely simple message was aimed at a globular cluster of stars known as M13 in the Milky Way Galaxy and at a distance of 30,000 light years from the Solar System. These efforts have been more symbolic than anything else, however. Further, a possible answer needs double the travel time, i.e. tens of years (near stars) or 60,000 years (M13).
Other methods
It has also been proposed that higher frequency signals, such as lasers operating at visible light frequencies, may prove to be a fruitful method of interstellar communication; at a given frequency it takes surprisingly small energy output for a laser emitter to outshine its local star from the perspective of its target.
Other more exotic methods of communication have been proposed, such as modulated neutrino or gravitational wave emissions. These would have the advantage of being essentially immune to interference by intervening matter.
Sending physical mail packets between stars may prove to be optimal for many applications. While mail packets would likely be limited to speeds far below that of electromagnetic or other light-speed signals (resulting in very high latency), the amount of information that could be encoded in only a few tons of physical matter could more than make up for it in terms of average bandwidth. The possibility of using interstellar messenger probes for interstellar communication — known as Bracewell probes — was first suggested by Ronald N. Bracewell in 1960, and the technical feasibility of this approach was demonstrated by the British Interplanetary Society's starship study Project Daedalus in 1978. Starting in 1979, Robert Freitas advanced arguments
for the proposition that physical space-probes provide a superior mode of interstellar communication to radio signals, then undertook telescopic searches for such probes in 1979 and 1982.
See also
Interplanetary Internet
List of interstellar radio messages
Universal translator
Gravitational lens
References
External links
Science fiction themes
Search for extraterrestrial intelligence
Telecommunications | Interstellar communication | Technology | 690 |
31,415,089 | https://en.wikipedia.org/wiki/HTML5%20File%20API | HTML5 File API aspect provides an API for representing file objects in web applications and programmatic selection and accessing their data. In addition, this specification defines objects to be used within threaded web applications for the synchronous reading of files. The File API describes how interactions with files are handled, for reading information about them and their data as well, to be able to upload it. Despite the name, the File API is not part of HTML5.
See also
File select
HTML5
W3C Geolocation API
Binary Large Object
References
HTML5 File Writer API
HTML5 File API
Reading local files in JavaScript
A state of limbo: the html5 file api, filereader, and blobs
Geolocation API
External links
HTML5 Video Player
HTML5 | HTML5 File API | Technology | 159 |
22,017,760 | https://en.wikipedia.org/wiki/Journal%20of%20Enzyme%20Inhibition%20and%20Medicinal%20Chemistry | The Journal of Enzyme Inhibition and Medicinal Chemistry is a peer-reviewed open access medical journal published by Taylor & Francis that covers research on enzyme inhibitors and inhibitory processes as well as agonist/antagonist receptor interactions in the development of medicinal and anti-cancer agents. The editor-in-chief is Claudiu T. Supuran.
Abstracting and indexing
The Journal of Enzyme Inhibition and Medicinal Chemistry is abstracted and indexed in:
External links
Medicinal chemistry journals
Enzyme inhibitors
Academic journals established in 1985
Bimonthly journals | Journal of Enzyme Inhibition and Medicinal Chemistry | Chemistry | 106 |
1,127,106 | https://en.wikipedia.org/wiki/Ivar%20Jacobson | Ivar Hjalmar Jacobson (; born September 2, 1939) is a Swedish computer scientist and software engineer, known as a major contributor to UML, Objectory, Rational Unified Process (RUP), aspect-oriented software development, and Essence.
Biography
Ivar Jacobson was born in Ystad, on September 2, 1939. He received his Master of Electrical Engineering degree at Chalmers Institute of Technology in Gothenburg in 1962. After his work at Ericsson, he formalized the language and method he had been working on in his PhD at the Royal Institute of Technology in Stockholm in 1985 on the thesis "Language Constructs for Large Real Time Systems".
After his master's degree, Jacobson joined Ericsson and worked in R&D on computerized switching systems AKE and AXE including PLEX. In April 1987, he started Objective Systems. A majority stake of the company was acquired by Ericsson in 1991, and the company was renamed Objectory AB. Jacobson developed the software method Object-Oriented Software Engineering (OOSE) published 1992, which was a simplified version of the commercial software process Objectory (short for Object Factory).
In October, 1995, Ericsson divested Objectory to Rational Software, and Jacobson started working with Grady Booch and James Rumbaugh. When IBM bought Rational in 2003, Jacobson decided to leave. He formed Ivar Jacobson International (IJI) in mid-2004, which operates with offices in the UK and Sweden.
IJI has developed several products providing use cases for Essence, the latest being Essence WorkBench.
In 2000, with Agneta Jacobson, he founded Jaczone AB which developed a tool, Waypointer, to support RUP using intelligent agent techniques. Waypointer received a JOLT award in 2004.
Ivar Jacobson was rewarded the Gustaf Dalén medal from Chalmers University in 2003, and received an honorary doctorate at San Martin de Porres University, Peru, in 2009.
Work
Summary
Dr. Ivar Jacobson's contributions span over 50 years, starting from components and architecture in 1967 and still ongoing today with Essence, which is described as "a common ground for engineering". He also created Use Cases, and co-created UML and the Rational Unified Process. His software products include Objectory and the intelligent agent tool Waypointer.
Ericsson
In 1967 at Ericsson, Jacobson proposed software components in the new generation of software controlled telephone switches Ericsson was developing. In doing this he also invented sequence diagrams, and developed collaboration diagrams. He also used state transition diagrams to describe the message flows between components.
Jacobson saw a need for blueprints for software development. He was one of the original developers of the Specification and Design Language (SDL). In 1976, SDL became a standard in the telecoms industry.
In 1986, he also invented use cases as a way to specify functional software requirements.
Rational Software
At Rational, Jacobson and his colleagues, Grady Booch and James Rumbaugh, became the original developers of UML, and his Objectory Process evolved to become the Rational Unified Process under the leadership of Philippe Kruchten.
Essential Unified Process
In November 2005, Jacobson announced the Essential Unified Process or “EssUP” for short. EssUP was a new “Practice”-centric software development process derived from established software development practices. It integrated practices sourced from three different process camps: the unified process camp, the agile software development camp, and the process improvement (primarily the Capability Maturity Model Integration (CMMI)) camp. Each one of them contributed different capabilities: structure, agility, and process improvement.
Ivar has described EssUP as a "super light and agile" RUP. IJI have integrated EssUP into Microsoft Visual Studio Team System and Eclipse.
EssWork
Standing on the experience of EssUP Ivar and his team, in particular Ian Spence and Pan Wei Ng, developed EssWork starting in 2006. EssWork is a framework for working with methods. It is based on a kernel of universal elements always prevalent in software development endeavors. On top of the kernel some fifteen practices were defined. A team can create their own method by composing practices.
SEMAT and Essence
In November 2009, Jacobson, Bertrand Meyer, and Richard Soley ("the Troika") started an initiative called SEMAT (Software Engineering Method and Theory) to seek to develop a rigorous, theoretically basis for software engineering practice, and to promote its wide adoption by industry and academia. SEMAT has been inspired by the work at IJI, but with a fresh new start. Essence, an OMG standard since November 2014, is the end result of SEMAT. Methods are created as compositions of reusable pratices.
Publications
Jacobson has published numerous books and articles. A selection:
1992. Object-Oriented Software Engineering: A Use Case Driven Approach (ACM Press) With Magnus Christerson, Patrik Jonsson & Gunnar Overgaard. Addison-Wesley, 1992,
1994. The Object Advantage: Business Process Reengineering With Object Technology (ACM Press). With M. Ericsson & A. Jacobson. Addison-Wesley,
1997. Software Reuse: Architecture, Process, and Organization for Business Success (ACM Press). With Martin Griss & Patrik Jonsson. Addison-Wesley, 1997,
1998. The Unified Modeling Language Reference Manual. With Grady Booch & James Rumbaugh. Addison-Wesley Professional, 2004,
1998. The Unified Modeling Language User Guide. With Grady Booch & James Rumbaugh. Addison-Wesley Professional, 2005,
1999. The Unified Software Development Process. With Grady Booch & James Rumbaugh. Addison-Wesley Professional, 1999,
2000. The Road to the Unified Software Development Process. With Stefan Bylund. Cambridge University Press, 1999,
2004. Aspect-Oriented Software Development With Use Cases (Addison-Wesley Object Technology Series). With Pan-Wei Ng. Addison-Wesley,
2013. The Essence of Software Engineering - Applying the SEMAT Kernel. With Pan-Wei Ng, Paul Mc Mahon, Ian Spence, and Svante Lidman. Addison-Wesley, 2013, ISBN
2015. Software Engineering in the Systems Context. With Bud Lawson. College Publications, 2015,
2019. The Essentials of Modern Software Engineering - Free the Practices from the Method prisons. With Harold "Bud" Lawson, Pan-Wei Ng, Paul Mc Mahon, and Michael Goedicke. ACM Books & Morgan & Claypool publishers, 2019,
References
External links
Ivar Jacobson International
Ivar Jacobson's Blog
EssWork Website
1939 births
Living people
People from Ystad Municipality
KTH Royal Institute of Technology alumni
Software engineers
Swedish computer scientists
Unified Modeling Language
Ericsson people
Chalmers University of Technology alumni
20th-century Swedish inventors
People from Ystad
21st-century Swedish inventors | Ivar Jacobson | Engineering | 1,415 |
48,035,434 | https://en.wikipedia.org/wiki/Ozanimod | Ozanimod, sold under the brand name Zeposia, is an immunomodulatory medication for the treatment of relapsing multiple sclerosis and ulcerative colitis. It acts as a sphingosine-1-phosphate receptor (S1PR) agonist, sequestering lymphocytes to peripheral lymphoid organs and away from their sites of chronic inflammation.
The most common adverse reactions are upper respiratory infection, hepatic transaminase elevation, orthostatic hypotension, urinary tract infection, back pain, and hypertension.
Ozanimod was approved for medical use in the United States in March 2020, in the European Union in May 2020, and in Australia in July 2020.
Medical uses
In the United States, ozanimod is indicated for the treatment of adults with relapsing forms of multiple sclerosis, to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease; and with moderately to severely active ulcerative colitis.
In the European Union and in Australia, ozanimod is indicated for the treatment of adults with relapsing remitting multiple sclerosis.
Pharmacology
Potency and selectivity
The principle of autoimmune therapy based on targeting S1P receptors was established through the clinical work performed during development of fingolimod (trade name Gilenya), a non‐selective S1P modulator. The prospects for ozanimod (Scripps-Receptos compound RPC1063) depended upon demonstration of comparable or better activity and selectivity relative to fingolimod and other comparators. During the discovery phase of its development, ozanimod was shown to be a selective agonist of the S1P1 and S1P5 receptors. Specifically, in a discovery research report, ozanimod's equal potency and improved selectivity for S1P1 and S1P5 receptor family members were determined though a combination of inhibition, binding, and signalling assays for the S1P1, S1P2, S1P3, S1P4, and S1P5 receptor types alongside the same tests with fingolimod and other compounds.
Potency for ozanimod as an agonist of the S1P1 receptor type was established through observed sub-nanomolar EC50 values in GTPγS binding and cAMP inhibition assays, and for the S1P5 type through an observed nanomolar EC50 value in the GTPγS binding assay. Measured alongside its binding to the S1P2, S1P3, and S1P4 receptor types, these concentration-response results supported a conclusion of an improved selectivity profile, with selectivity of S1P1 over S1P5 receptors at 27‐fold, and selectivity for S1P1 over S1P2, S1P3, and S1P4 receptors greater than 10,000‐fold.
Also, these assays allowed comparison of ozanimod potency against and selectivity for S1P1 over other S1 receptors, relative to related S1 active agents siponimod and the phosphorylated (prodrug) forms of fingolimod and mocravimod, where ozanimod was similar to these comparators in S1P1 potency, but had the elevated selectivities stated above (versus fingolimod being potent in stimulating S1P3, S1P4, and S1P5, siponimod potent with a S1P5 form, and mocravimod active in some way against S1P3, S1P4, and S1P5), making its selectivity profile an improvement over all of these.
Hence, the study concluded that it had "established... RPC1063 [as] a potent agonist of the S1P1 receptor with additional agonist activity on the S1P5 receptor" with S1P1 activity "similar to other known, less selective S1P receptor agonists".
Mechanism of action, pharmacodynamics
The agonism of S1P directly causes its internalization and degradation through the ubiquitin-proteosome pathway. The loss of S1P leads to a decrease in the total lymphocyte count in circulation, specifically CD4+ CCR7+ and CD8+ CCR7+ T cells.
The most frequent adverse effects is an increase in liver enzymes (>10% ) and high blood pressure (4%) per product labeling.Kaposi sarcoma of the skin and colon was described in a single case s after treatment with ozanimod for 2 months.
Pharmacokinetics
Ozanimod has a high oral bioavailability, a circulating half-life of about 19 hours, and reaches highest blood plasma concentrations after about 6 hours. Ozanimod is dehydrogenated by two CYP enzymes into two active metabolites, all with similar pharmacokinetics. The decrease in lymphocyte count lasts for approximately 14 days after treatment discontinuation. Unlike fingolimod, it does not require phosphorylation for activation, nor does it demonstrate cardiac abnormalities.
History
Ozanimod was invented by Hugh Rosen, Edward Roberts, and colleagues at The Scripps Research Institute, and was subsequently out-licensed in the creation of the startup, Receptos Inc.
Celgene Corp acquired Receptos along with its intellectual property in 2015. Bristol Myers Squibb acquired Celgene in 2019 (and with it, ozanimod and the rest of its products and pipeline).
The US Food and Drug Administration (FDA) approved ozanimod based on evidence from two clinical trials (Trial 1/NCT02294058 and Trial 2/ NCT02047734) of 1767 subjects with relapsing forms of multiple sclerosis. The trials were conducted at 173 centers in the United States, Belarus, Poland, Russia and Ukraine. Subjects received ozanimod or comparator (interferon β1a, a product approved for the treatment of relapsing forms of multiple sclerosis) for up to one year (in Trial 1) or up to two years (in Trial 2). Neither the subjects nor the health care providers knew which treatment was being given until the trials were completed. The benefit of ozanimod was evaluated based on the percentage of subjects who experienced reduction in disease relapse in comparison to subjects treated with interferon β1a.
In May 2021, the FDA approved ozanimod for an additional indication for the treatment of moderately to severely active ulcerative colitis.
Clinical trials
Touchstone
Touchstone is a double-blind, placebo controlled phase II clinical for the treatment of ulcerative colitis. 197 patients, ages 18–75, with moderate to severe ulcerative colitis (Mayo Score 6–10) were recruited and assigned either placebo, 0.5 mg or 1 mg of oral ozanimod followed by 1 week of dose escalation. The 1 mg dose showed a slight increase in rate of clinical remission of ulcerative colitits and total lymphocyte decrease as compared to the placebo, with the most common adverse effects being headaches and anemia. The authors noted that limitations on this study included a brief duration and small sample size, meaning they could not assess safety nor efficacy.
Radiance
Radiance is a double-blind, placebo controlled phase combined II/III clinical trial for the treatment of relapsing multiple sclerosis. For the phase II trial, 258 patients, ages 18–55 with relapsing multiple sclerosis (mean Expanded Disability Status Scale of 2.9) were assigned either placebo, 0.5 mg or 1 mg of oral ozanimod followed by 1 week of dose escalation. Ozanimod significantly reduced MRI lesion activity in participants with relapsing multiple sclerosis over a period of 24 weeks. Both doses of ozanimod reached anticipated range of 60-70% decreased lymphocyte count, and were well tolerated, with a safety profile consistent with a previous phase 1 study in healthy volunteers. The most common adverse effects as compared to the placebo were: nasopharyngitis, headache, and urinary-tract infections, with no serious infectious or cardiac adverse effects. With these results, both doses of ozanimod were taken forward into the 2-year long phase III trial and is completed but unpublished as of November 2016.
Sunbeam
Sunbeam is the second relapsing multiple sclerosis phase III clinical trial to establish the dose with optimum safety-benefit relationship, with an estimated size of 1200 patients. It began in November 2014, and has an estimated completion date of February 2017.
Society and culture
Commercial
After going public in May 2013, Receptos, Inc. stock surged with the clinical data ozanimod displayed as a S1P immunomodulating drug. In August 2015, Receptos was acquired by Celgene for $7.2 billion through a combination of cash in hand and new debt, leading to a one-day 22% increase in Celgene stock value.
Receptos-Celgene patented the synthesis of ozanimod in July 2016. With the expansion of Celgene's inflammation and immunology profile, the company had been expecting to generate $4 to $6 billion in annual sales from ozanimod; however, in a "surprise development", the FDA rejected Celgene's initial application for the drug's approval in February 2018. Celgene refiled in March 2019.
The new owner of the product, Bristol Myers Squibb, received FDA approval for ozanimod (Zeposia) oral capsules on March 26, 2020, for the following adult indications: relapsing forms of multiple sclerosis, including relapsing-remitting multiple sclerosis, active secondary progressive multiple sclerosis, and clinically isolated syndrome. Ozanimod was approved for medical use in the European Union in May 2020, and in Australia in July 2020.
Research
Ozanimod is in development for additional immune-inflammatory indications, including Crohn's disease.
References
External links
1-Aminoindanes
Drugs developed by Bristol Myers Squibb
Ethanolamines
Immunomodulating drugs
Isopropyl compounds
Nitriles
Noninfective enteritis and colitis
Oxadiazoles
Phenol ethers
S1P receptor modulators | Ozanimod | Chemistry | 2,265 |
73,537,840 | https://en.wikipedia.org/wiki/Intranasal%20drug%20delivery | Intranasal drug delivery occurs when particles are inhaled into the nasal cavity and transported directly into the nervous system. Though pharmaceuticals can be injected into the nose, some concerns include injuries, infection, and safe disposal. Studies demonstrate improved patient compliance with inhalation. Treating brain diseases has been a challenge due to the blood brain barrier. Previous studies evaluated the efficacy of delivery therapeutics through intranasal route for brain diseases and mental health conditions. Intranasal administration is a potential route associated with high drug transfer from nose to brain and drug bioavailability.
History of drug delivery
Drug delivery is a process of administering therapeutics to treat human diseases. The first drug delivery system is often dated to the 1950s, when Smith Kline & French Laboratories introduced the Spansule technology. Between 1950s and 1980s, there were four drug release systems developed for oral and transdermal applications: dissolution, diffusion, osmosis, and ion-exchange controlled release. Later in the 1980s, the Lupron Depot technology further advanced the field by offering zero-order and long-term release systems. The intranasal route gained interest towards the end of the 20th century with treating cardiovascular and respiratory diseases. During the late 1980s, William Frey II studied the intranasal route for treating brain diseases. Ever since, it has become a potential route for nose-to-brain delivery.
Anatomy
Intranasal delivery pathway
The nasal cavity is highly vascularized, allowing efficient transfer of molecules directly to the nervous system. Compared to other administration routes, nasal drug delivery increases bioavailability and reduces systemic exposure risks. The nasal cavity’s slightly acidic environment and enzymes can affect drug degradation, making delivery systems with neutral to acidic pH ideal. The respiratory region, with its large surface area and high vascularization, is the primary site for drug absorption into systemic circulation. Targeting the olfactory region enhances nose-to-brain drug delivery, as particles can travel via the olfactory nerve to the brain. This route offers potential for treating brain diseases and mental health conditions.
Blood brain barrier
The blood-brain barrier (BBB) is a semipermeable membrane that separates the blood from the brain’s interstitial fluid. It is formed by tight junctions between endothelial cells, astrocytes, and pericytes in the brain’s capillaries, and has high electrical resistance. The BBB is crucial for protecting the brain from pathogens and toxic substances, maintaining homeostasis, and preventing alterations to neuronal functions. However, some diseases can damage the BBB, causing leakage. Research suggests that increasing intake of vitamins and antioxidants, as well as reducing stress, can help restore the BBB. Due to its selective nature, the BBB restricts the passive diffusion of solutes, large and hydrophilic molecules, and immune factors, making it challenging to deliver pharmaceuticals directly to the brain.
Recent studies on nose-to-brain drug delivery
Alzheimer's
Neurodegenerative diseases occur from loss of neuronal structure and function. This progressive degeneration of neurons is irreversible. Alzheimer's is a neurodegenerative disease that begins with short-term memory loss progressing to loss of control over heartbeat and breathing. It has been over 100 years since Alois Alzheimer first presented the world disease to the world in 1906. There is evidence for the efficacy of intranasal delivery to treat Alzheimer's. Intranasal delivery of insulin showed greater memory improvement in patients with Alzheimer's than in healthy individuals. Increased microglial activation inflammation are characteristics of Alzheimer's. Animal studies show intranasal administration of pro-resolving lipid mediators decreased both factors, slowing pathogenesis of this disease. Delivering a novel peptide via intranasal route reduced amyloid beta plaques, a defining trait of Alzheimer's and enhanced cognitive functions. Intranasal delivery of anti-Alzheimer's drug dispersed through hydrogel in rabbits demonstrated higher bioavailability compared to oral tablets. MiR132 is an RNA molecule that regulates neuronal morphology and maintains survival. This molecule is downregulated with Alzheimer's. A study administered PEG-PLA nanoparticles loaded with this miRNA to mice through the nasal route. This novel therapy showed increased expression of miR132 and improved memory function. To strengthen the effectiveness of intranasal delivery, there are studies to develop permeation enhancers to better improve drug transport across the blood brain barrier.
Glioblastoma
Abnormal cell growth and formation of mass in the brain tissue or nearby regions may cause brain cancer. Constant headaches, seizures, and blurred vision are common symptoms. Glioblastoma (GBM) is the most fast-growing and deadliest brain tumor. Though the main cause of glioblastoma remains unknown, it originates when astrocytes mutate and multiply uncontrollably forming tumors in the frontal and temporal lobes of the brain. The challenge with current therapeutics is to initiate tumor cell apoptosis with no toxic effects to healthy brain tissue. Nanoparticles loaded with chemotherapeutics delivered through the intranasal route show promising results in treating glioblastoma. PLGA-based nanoparticles loaded with paclitaxel or doxorubicin conjugated with a RGD sequence targeted the glioblastoma microenvironment and reduced tumor volume through cell death. MicroRNA-21 (miR-21) inhibits pro-apoptotic genes increasing progression of glioblastoma. Self-assembling nanoparticles produced with anti-tumor peptides were administered intranasally and reduced miR-21 levels increasing tumor cell apoptosis.
Epilepsy
Infection, head injury, or strokes can cause sudden bursts of neuronal activity leading to abnormal behaviors, muscle movement, and mood changes. This condition is known as seizure. Epilepsy is characterized by recurring seizures. Some possible causes of epilepsy include imbalance or disruption of neurotransmitters, strokes, or brain injury. Intranasal delivery of carbamazepine nanoparticles increase antiepileptic drug bioavailability. Administering a self-assembling hydrogel with neuroactive drugs to treat Parkinson's disease appears to be biocompatible, low in toxicity, and have a good recovery capacity. Nasal delivery of this gel demonstrated increased drug concentration in the brain. Oxytocin is a hormone which is observed to alleviate anxiety symptoms in people with autism. Intranasal administration indicated efficient transfer of pharmacologically active oxytocin from nasal cavity to brain.
Parkinson's
Similar to Alzheimer's, Parkinson's is the most common neurodegenerative disease associated with balance and coordination issues, muscle stiffness, and tremors. During the early 1800s, James Parkinson medically defined this disease. A study observed improvement in locomotor abilities in rats with Parkinson's after intranasal delivery of conjugated mitochondrial systems. Another study demonstrated delivery of neuroactive drugs in a hydrogel increased residence times in the nasal cavity and concentration in the brain. Administering therapeutics combined with nanocarriers is shown to directly transfer drugs to the target cells and enhance accumulation. The observed effects include improved neuronal signaling and locomotion. Furthermore, intranasal delivery of biodegradable nanoparticles surface-modified with lactoferrin increase accumulation in the brain and cellular uptake.
Depression
Characterized by loss of neuroplasticity, depression is a common mood disorder causing persistent negative emotions and changes in lifestyle. Intranasal delivery of relaxin-3 mimetics demonstrated significant anti-depressant activity in behavior paradigms of rat models. Delivering a thermoresponsive hydrogel loaded with berberine intranasally exhibited high bioavailability in hippocampus and anti-depressant activity.
Anxiety
Anxiety can impair hippocampus function which increases risk of depression and dementia. Anxiolytic effects were observed in animal models post-intranasal delivery of a loaded polymeric nanoparticles. Another study indicated intranasal delivery of neuropeptide Y lowered anxiety in rats.
Anorexia nervosa
Anorexia nervosa (AN) is a common eating disorder characterized by low intake of food from fear of weight gain. Several complications are associated with this chronic disorder such as fatigue, insomnia, and low blood pressure. Intranasal administration of oxytocin in patients with AN significantly lowered food anticipation and eating concern.
Substance use disorder
Uncontrolled and continuous use of a substance, drugs or alcohol, is known as substance use disorder. Substances can interfere with neuronal signaling and potentially disrupt the brain circuit. Addiction to these substances impairs thinking, behavior, and other biological functions. Intranasal delivery of insulin is associated with improvement in brain metabolic activities and alleviate impulsivity. Opioid addiction is prevalent and associated with many substance abuse deaths. A study observed high biodistribution in the brain and reduction in opioid overdose in rats administered with naloxone-loaded lipid nanoparticles.
Post-traumatic stress disorder
Witnessing a devastating or terrifying situation can lead to post-traumatic stress disorder (PTSD). This mental health condition triggers anxiety, depression, and extreme fear with memories. Intranasal administration of temperature-sensitive hydrogels loaded with PTSD medications showed enhanced brain targeting effects and tissue distribution. Similarly, another study observed anti-PTSD effects with intranasal administration of loaded hydrogels.
Schizophrenia
Schizophrenia is a chronic mental health condition caused by changes in brain chemistry and structure. Genetics and environment are hypothesized to play a key role in development of this disorder. Research suggests impaired gene expression or chemical imbalance may impact this condition. Anxiety can increase risk of schizophrenia and symptoms include hallucinations, disorganized speech, and abnormal behavior. Davunetide (NAP) is a segment of activity-dependent neuroprotective protein (ADNP). ADNP is reported be downregulated with schizophrenia. A study observed decreased hyperactivity in mice when treated with NAP via the intranasal route.
Migraine
Migraine occurs with episodes of intense headache causing nausea and throbbing pain. Stress and hormonal changes can be a trigger migraine. A nasal spray containing sumatriptan demonstrated a significant reduction of migraine pain. Further clinical studies of intranasal administration of sumatriptan (ST) can help evaluate efficacy and safety of such delivery systems. Since its approval by the FDA in 2021, dihydroergotamine mesylate has been administered through nasal sprays to treat migraines.
Nanosystems for Intranasal Drug Delivery
Nanoparticles are drug delivery systems ranging from 1–1000 nm in diameter. Lipid-based and polymer-based nanocarriers are commonly used for nose-to-brain delivery as they exert high stability, solubility, and adherence. Exosomes and dendrimers are other potential nanocarriers. Nanosystems can be synthesized either using physical or chemical methods. A few physical methods include evaporation-condensation reaction and laser ablation. Irradiation, microemulsion, and chemical reduction are common chemical techniques to develop nanoparticles. Sonication, electroporation, and incubation are common methods to load drugs into nanocarriers.
Coating these nanosystems with mucoadhesive agents, stimulus-sensitive materials, or antibodies can enhance biocompatibility, clearance rates, specificity, and bioavailability. Penetration and absorption enhancers can significantly increase the overall efficacy of the system. Imaging studies along with measurement of drug transfer efficiency and bioavailability can further support the role of these drug delivery systems.
Lipid-based nanoparticles
Lipid-based nanoparticles (LNP) can deliver molecules with low toxicity and controlled release. Liposomes, solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), and nanoemulsions are examples.
Liposomes are made up of phospholipids forming spherical vesicles. This property enables liposomes to exhibit high biocompatibility and biodegradability. Studies report potential application of liposomes to treat brain diseases due to increased retention and absorption in nasal cavity, and high brain biodistribution. A previous study developed a cationic liposome loaded with mRNA and green fluorescent protein (GFP). Intranasal delivery of this formulation in murine models demonstrated high brain biodistribution and expression of mRNA-GFP.
Solid lipid nanoparticles (SLNs) are made up of solid lipids forming a matrix and stabilized by surfactants. They exhibit high physical stability and remain in solid state at different temperatures. Based on a study, intranasal delivery of SLNs loaded with rivastigmine tartrate (RT) exhibited no toxicity, stability, and improved bioavailability. Sometimes burst release may occur due to rigidity and less flexibility in shape.
Nanostructured lipid carriers (NLC) are synthesized by a mixture of solid and aqueous lipids. NLC's are developed from SLNs, thus referred to as second generation LNPs. Intranasal administration of NLC loaded with curcumin (CRM) increased biodistribution and concentration in brain after emerging as a potential system for brain cancer.
Small colloidal systems made of micelles containing oil, aqueous phases, and emulsifiers are called nanoemulsions. Intranasal delivery of gel nanoemulsion loaded with temozolomide is observed to exhibit sustained release and better permeation from nose to brain to treat glioblastoma.
Polymer-based nanoparticles
Polymer-based nanoparticles can be made from either natural or synthetic sources. Nanospheres and nanocapsules are polymeric nanoparticle systems. Natural polymers can be found in the environment or human body. On the other hand, synthetic polymers do not occur naturally and are artificially developed polymers with chemical modifications. Natural polymer-based nanoparticles can be made up of chitosan, hyaluronic acid, alginate, and gelatin. Natural polymers exhibit excellent biocompatibility and biodegradability, and low toxicity. Synthetic polymer-based nanoparticles can consist of poly (glycolic acid) (PGA), poly (lactic acid) (PLA), and poly(L-lactide-co-glycolide) (PLGA).
A study evaluated chitosan nanoparticles loaded with an anti-epileptic drug, phenytoin (PHT), to treat epilepsy. Observations suggested high stability, sustained release, and bioavailability when these particles where administered via the intranasal route. Similarly, administering PLGA nanoparticles loaded lamotrigine (LTG), polymer-based nanoparticle, showed better permeation through BBB and higher bioavailability.
Exosomes
Exosomes are vesicular structures containing genetic information. Recently, exosomes are being utilized as drug carriers. These systems are observed to be stable, specific, and safe. Moreover, delivery of exosomes shows less immunogenic affects. Further surface modifications and conjugation with liposomes enhances the therapeutic effects. Based on a previous study, intranasal delivery of exosomes loaded with a Stat3 inhibitor reduced brain inflammation and slowed brain tumor growth.
Dendrimers
Dendrimers are polymeric macromolecules with a branched network similar to a tree structure. Generally, they are spherical and homogeneous. Surface charge and molecule chemistry can play crucial role with drug interaction and release. Poly(amidoamine) (PAMAM) dendrimers are the most commonly used system. A study investigated potential application of dendrimer-based formulation of haloperidol. Intranasal administration showed improved targeting, and solubility as well as high concentrations in the brain. Drugs can be loaded in dendrimers through formulation and nanoconstruct.
Importance of physiochemical properties
For drug delivery systems to bypass the blood brain barrier, modifications of physiochemical properties can enhance safety and efficacy. Size, surface charge, and lipophilicity play a major role in substance bypassing the blood brain barrier. Smaller, positively charged, or more lipophilic molecules enhance efficacy of nose-to-brain delivery. Decrease in delivery system size increases permeation. As the membrane is negatively charged, a particle with positive surface charge interacts electrostatically which enhances bioadhesion. Carriers with more lipophilicity exert better mucoadhesion and residence time. Drug system pH, solubility, and hydrogen bonding potential are other physiochemical properties which should be evaluated.
References
Drug delivery devices | Intranasal drug delivery | Chemistry | 3,538 |
16,369,918 | https://en.wikipedia.org/wiki/Plutonium%20hexafluoride | Plutonium hexafluoride is the highest fluoride of plutonium, and is of interest for laser enrichment of plutonium, in particular for the production of pure plutonium-239 from irradiated uranium. This isotope of plutonium is needed to avoid premature ignition of low-mass nuclear weapon designs by neutrons produced by spontaneous fission of plutonium-240.
Preparation
Plutonium hexafluoride is prepared by fluorination of plutonium tetrafluoride (PuF4) by powerful fluorinating agents such as elemental fluorine.
+ →
This reaction is endothermic. The product forms relatively quickly at temperatures of 750 °C, and high yields may be obtained by quickly condensing the product and removing it from equilibrium.
It can also be obtained by fluorination of plutonium(III) fluoride, plutonium(IV) oxide, or plutonium(IV) oxalate at approximately 700 °C:
2 + 3 → 2
+ 3 → +
+ 3 → + 4
Alternatively, plutonium(IV) fluoride oxidizes in an 800-°C oxygen atmosphere to plutonium hexafluoride and plutonium(IV) oxide:
3 + → 2 +
In 1984, the synthesis of plutonium hexafluoride at near–room-temperatures was achieved through the use of dioxygen difluoride. Hydrogen fluoride is not sufficient even though it is a powerful fluorinating agent. Room temperature syntheses are also possible by using krypton difluoride or irradiation with UV light.
Properties
Physical properties
Plutonium hexafluoride is a red-brown volatile solid, crystallizing in the orthorhombic crystal system with space group Pnma and lattice parameters , , and . It sublimes around 60 °C with heat 12.1 kcal/mol to a gas of octahedral molecules with plutonium-fluorine bond lengths of 197.1 pm. At high pressure, the gas condenses, with a triple point at 51.58 °C and ; the heat of vaporization is 7.4 kcal/mol. At temperatures below -180 °C, plutonium hexafluoride is colorless.
Plutonium hexafluoride is paramagnetic, with molar magnetic susceptibility 0.173 mm3/mol.
Spectroscopic properties
Plutonium hexafluoride admits six different oscillation modes: stretching modes , , and and rotational modes , , and . The Raman spectrum cannot be observed, because irradiation at 564.1 nm induces photochemical decomposition. Irradation at 532 nm induces fluorescence at 1900 nm and 4800 nm; irradiation at 1064 nm induces fluorescence about 2300 nm.
Chemical properties
Plutonium hexafluoride is relatively hard to handle, being very corrosive, poisonous, and prone to auto-radiolysis.
Reactions with other compounds
PuF6 is stable in dry air, but reacts vigorously with water, including atmospheric moisture, to form plutonium(VI) oxyfluoride and hydrofluoric acid.
+ 2 → + 4
It can be stored for a long time in a quartz or pyrex ampoule, provided there are no traces of moisture, the glass has been thoroughly outgassed, and any traces of hydrogen fluoride have been removed from the compound.
An important reaction involving PuF6 is the reduction to plutonium dioxide. Carbon monoxide generated from an oxygen-methane flame can perform the reduction.
Decomposition reactions
Plutonium hexafluoride typically decomposes to plutonium tetrafluoride and fluorine gas. Thermal decomposition does not occur at room temperature, but proceeds very quickly at 280 °C. In the absence of any external cause for decomposition, the alpha-particle current from plutonium decay will generate auto-radiolysis, at a rate of 1.5%/day (half-time 1.5 months) in solid phase. Storage in gas phase at pressures 50–100 torr (70–130 mbar) appears to minimize auto-radiolysis, and long-term recombination with freed fluorine does occur.
Likewise, the compound is photosensitive, decomposing (possibly to plutonium pentafluoride and fluorine) under laser irradiation at a wavelength of less than 520 nm.
Exposure to laser radiation at 564.1 nm or gamma rays will also induce rapid dissolution.
Uses
Plutonium hexafluoride plays a role in the enrichment of plutonium, in particular for the isolation of the fissile isotope 239Pu from irradiated uranium. For use in nuclear weaponry, the 241Pu present must be removed for two reasons:
It generates enough neutrons by spontaneous fission to cause an uncontrollable reaction.
It undergoes beta decay to form 241Am, leading to the accumulation of americium over long periods of storage which must be removed.
The separation between plutonium and the americium contained proceeds through reaction with dioxygen difluoride. Aged PuF4 is fluorinated at room temperature to gaseous PuF6, which is separated and reduced back to PuF4, whereas any AmF4 present does not undergo the same conversion. The product thus contains very little amounts of americium, which becomes concentrated in the unreacted solid.
Separation of the hexafluorides of uranium and plutonium is also important in the reprocessing of nuclear waste. From a molten salt mixture containing both elements, uranium can largely be removed by fluorination to UF6, which is stable at higher temperatures, with only small amounts of plutonium escaping as PuF6.
History
Shortly after plutonium's discovery and isolation in 1940, chemists began to postulate the existence of plutonium hexafluoride. Early experiments, which sought to mimic methods for the construction of uranium hexafluoride, had conflicting results; and definitive proof only appeared in 1942. The Second World War then interrupted the publication of further research.
Initial experiments, undertaken with extremely small quantities of plutonium, showed that a volatile plutonium compound would develop in a stream of fluorine gas only at temperatures exceeding 700 °C. Subsequent experiments showed that plutonium on a copper plate volatilized in a 500-°C fluorine stream, and that the reaction rate decreased with atomic number in the series uranium > neptunium > plutonium. Brown and Hill, using milligram-scale samples of plutonium, completed in 1942 a distillation experiment with uranium hexafluoride, suggesting that higher fluorides of plutonium ought be unstable, and decompose to plutonium tetrafluoride at room temperature. Nevertheless, the vapor pressure of the compound appeared to correspond to that of uranium hexafluoride. Davidson, Katz, and Orlemann showed in 1943 that plutonium in a nickel vessel volatilized under a fluorine atmosphere, and that the reaction product precipitated on a platinum surface.
Fisher, Vaslow, and Tevebaugh conjectured that the higher fluorides exhibited a positive enthalpy of formation, that their formation would be endothermic, and consequently only stabilized at high temperatures.
In 1944, prepared a volatile compound of plutonium believed to be the elusive plutonium hexafluoride, but the product decomposed prior to identification. The fluid substance would collect onto cooled glass and liquify, but then the fluoride atoms would react with the glass.
By comparison between uranium and plutonium compounds, Brewer, Bromley, Gilles, and Lofgren computed the thermodynamic characteristics of plutonium hexafluoride.
In 1950, Florin's efforts finally yielded the synthesis, and improved thermodynamic data and a new apparatus for its production soon followed. Around the same time, British workers also developed a method for the production of PuF6.
References
Plutonium compounds
Hexafluorides
Octahedral compounds
Actinide halides
Nuclear materials | Plutonium hexafluoride | Physics | 1,685 |
24,887,696 | https://en.wikipedia.org/wiki/Quantapoint | Quantapoint, Inc. is a technology and services company that develops and uses patented 3D laser scanning hardware and software. Quantapoint creates a Digital Facility using 3D laser scanning and then provides visualization, analysis, quality control, decision support and documentation services for buildings, museums, refineries, chemical plants, nuclear and fossil-fuel power plants, offshore platforms and other structures.
History
Quantapoint was founded as K2T, Inc (or K2T) in Pittsburgh, Pennsylvania in 1991 by Eric Hoffman, Pradeep Khosla, Takeo Kanade and other Carnegie Mellon University faculty members. K2T focused on creating custom robotics and 3D range-finding imaging systems to help them navigate complex environments. The most notable are the laser range-finding system created in 1992 for the DANTE walking robot that explored Mount Erebus in Antarctica as part of a NASA sponsored competition and the 360-degree phase-based 3D laser scanner named SceneModeler created in 1997.
The company name was changed to Quantapoint in 1999 to reflect the focus on 3D laser scanning hardware, software and services.
Initially, Quantapoint focused on using 3D laser scanning to "digitize" buildings and create 2D drawings, 3D models and/or other animations or visualizations for renovations, additions or historic preservation. Notable projects include the Museum of Modern Art, the Theban Mapping Project in the Valley of the Kings, Monticello and the Guggenheim Museum.
Since 2002, Quantapoint has served the chemical, petroleum and power industries both globally and within the United States. Quantapoint has also worked with the United States General Services Administration (GSA).
Quantapoint has received several patents and awards for the 3D laser scanner hardware and 3D laser scanning data software that it has developed.
3D laser scanner hardware
Quantapoint uses both its own 3D laser scanner hardware, the SceneModeler 5 and SceneModeler 9, and the Photon from Faro Systems. Quantapoint has a fleet of more than twenty (20) 3D laser scanners.
Digital facility
The Quantapoint Digital Facility consists of the following:
Laser Models: Quantapoint technology that integrates all 3D laser scanning data to provide detailed, high-definition 3D solid "models" of a facility. Quantapoint avoids using the term "point cloud" or "cloud of points".
Laser Images: Photo-realistic, perspective-corrected panoramic images of individual 3D laser scans.
3D laser scanning data software
Quantapoint provides the following software for using the 3D laser scanning data in the Digital Facility:
PRISM 3D: View and interact with Laser Images and Laser Models directly.
CAD Conversion Option for PRISM 3D: Import 3D CAD models into PRISM 3D to view with or clash against Laser Models.
QuantaCAD: View and interact Laser Images and Laser Models within 3D computer-aided design (CAD) software, including AutoCAD, AutoPlant, AVEVA Review, MicroStation XM, PDS, PDMS, Revit, SmartMarine 3D, SmartPlant Review and SmartPlant 3D.
AccessPoint: View and interact Laser Images and Laser Models via the Internet and integrate with facility information.
Alliances/software development relationships
Quantapoint has alliances or software development relationships to integrate laser data with software from Autodesk, AVEVA, Bentley Systems and Intergraph.
Locations
Quantapoint has locations within the United States (Pittsburgh, Houston, Los Angeles), England, Scotland and Nigeria. Quantapoint also uses representatives in various countries, such as Mexico, Venezuela, South Africa, Malaysia and Brazil.
Patents
Quantapoint has been issued the following patents in the United States and has filed for similar patents in the EU, Canada and Japan:
360-degree 3D Laser Scanning: 6,034,803, 6,373,612, 6,906,837 and 7,365,891.
3D Laser Scan Registration: 7,180,072.
Creating Layout from 3D Laser Scan Data: 6,446,030 and 7,127,378.
References
External links
Building information modeling
Electronics companies established in 1991
Companies based in Pittsburgh
GIS companies
Software companies based in Pennsylvania
Laser companies
1991 establishments in Pennsylvania
Defunct software companies of the United States
Defunct electronics companies of the United States | Quantapoint | Engineering | 872 |
33,775,942 | https://en.wikipedia.org/wiki/Queen%20Elizabeth%20Prize%20for%20Engineering | The Queen Elizabeth Prize for Engineering, also known as the QEPrize, is a global prize for engineering and innovation. The prize was launched in 2012 by a cross-party group consisting of David Cameron, Nick Clegg, and Ed Miliband, then Prime Minister, Deputy Prime Minister and Leader of the Opposition of the United Kingdom. The £500,000 prize, and 3D printed trophy, are awarded annually in the name of Queen Elizabeth II (the prize was biennial until 2021).
The prize is run by the Queen Elizabeth Prize for Engineering Foundation, a charitable company. The Foundation is chaired by Sir Patrick Vallance, with Yewande Akinola, John Hennessy, Anji Hunter, Robert Langer, Professor Sir Jim McDonald and Dame Anne Richards serving as trustees. The QEPrize is funded by donations from the following international companies: BAE Systems, BP, GSK, Hitachi Ltd., Jaguar Land Rover, National Grid, Nissan Motor Corporation, Shell, Siemens UK, Sony, Tata Consultancy Services, Tata Steel and Toshiba.
The Prize
The Queen Elizabeth Prize for Engineering is awarded for engineering-led advances that are judged to be of tangible and widespread benefit to the public. The foundation invites nominations from the public, engineering and science academies, universities, research organisations, and commercial organisations from anywhere in the world; self-nomination is not permitted, and the prize is not awarded posthumously.
The judging panel works from the information provided in the nomination, comments from referees and any additional information required in order to establish which nomination most fully meets the following prize criteria:
What is it that this person has done (or up to five people have done) that is a ground-breaking innovation in engineering?
In what way has this innovation been of global benefit to humanity?
Is there anyone else who might claim to have had a pivotal role in this development?
The winner(s) of the QEPrize are announced every year by the Chairman of the QEPrize Foundation. In the first four prize cycles, this announcement was held at the Royal Academy of Engineering and was attended by members of the British Royal Family. The QEPrize award ceremony takes place in the same year as the announcement. The QEPrize trophy is designed by the winner of the Create the Trophy competition, presented to the winner(s) by a member of the Royal Family. In the first two prize cycles, the trophy was presented by the Queen. In subsequent cycles, the trophy has been presented by the King, formally the Prince of Wales.
Winners
Judging Panel
In 2022, the judges for the Queen Elizabeth Prize for Engineering were: Professor Jim Al-Khalili, Dr John Anderson, Professor Brito Cruz, Dr Jean-Lou Chameau, Josephine Cheng, Abdigani Diriye, Alan Finkel, Professor Jinghai Li, Ilya Espino de Marotta, Raghunath Anant Mashelkar, Professor Tatsuya Okubo, Professor Viola Vogel, Paul Westbury, and Henry T. Yang.
The Chair of Judges include: Lord Alec Broers (2013–2015), Sir Christopher Snowden (2015–2021) and Professor Dame Lynn Gladden (2022–present).
QEPrize Ambassador Network
The QEPrize Ambassador Network is an international network that brings together the best and brightest early-career engineers from all fields around the world, who work to inspire the next generation to take up the challenges of the future. QEPrize ambassadors act as evangelists for engineering, engaging with teachers, parents, school children, politicians, and journalists about their work and why engineering is such an important profession. The Ambassador Network became a global community in 2016.
The Engineers' Gallery in the Science Museum
The QEPrize is a major funder of the Engineers' Gallery which opened in June 2023 in the Science Museum, London. The gallery features all QEPrize winners arranged around the themes of Bodies, Lives, Communications and Creating.
Create the Trophy competition
The QEPrize trophy is designed by the winner of the Create the Trophy competition which, like the prize itself, runs annually. The competition is open to those aged between 14 and 24, and is intended to encourage young people to develop 3D design skills. Entries are submitted online through an app.
Winners
2013: Jennifer Leggett, 17. Leggett was invited to spend the day with designer Thomas Heatherwick before the design was finalised.
2015: Euan Fairholm, 20, a mechanical engineering student at The University of Glasgow. His design, "The Golden Crown", was developed into a final form by BAE Systems and presented to Dr Robert Langer, the winner of the 2015 QEPrize.
2017: Samuel Bentley, 15, from Wales. His design was 3D printed by BAE Systems, and presented to the 2017 QEPrize winners at Buckingham Palace.
2019: Jack Jiang, 16, from Hong Kong.
2021: Hannah Goldsmith, 20, from the United Kingdom.
2022: Anshika Agarwal, 17, from India.
2023: Anja Brandl, from Switzerland.
See also
List of engineering awards
References
External links
Awards established in 2012
International awards
2011 establishments in the United Kingdom
Engineering
Engineering awards | Queen Elizabeth Prize for Engineering | Technology | 1,057 |
52,678,942 | https://en.wikipedia.org/wiki/Mammillaria%20elegans | Mammillaria elegans is a species of cacti in the tribe Cacteae. It is native to Mexico. Mammillaria elegans A.P. de Candolle 1828. is a 'nomen confusum' (confused name) also applied to Mammillaria haageana subsp. elegans and refers both to Mammillaria geminispina with latex in the stem (subgenus Mammillaria section Hydrochylus series supertextae ) and to Mammillaria haageana, without latex in the stem (subgenus Mammillaria, section Galactophylous, series Leucocephale)
Habit: Solitary, seldom branching cactus.
Names brought to synonymy:
Mammillaria elegans var. supertexta (Mart.) Schelle, 1907 or Mammillaria elegans var. lanata (Britton & Rose) B.Hofmann, 1986, synonyms for Mammillaria supertexta
References
External links
Mammillaria elegans at Tropicos
Plants described in 1828
elegans
Controversial plant taxa | Mammillaria elegans | Biology | 240 |
2,865,082 | https://en.wikipedia.org/wiki/Fusion%20rules | In mathematics and theoretical physics, fusion rules are rules that determine the exact decomposition of the tensor product of two representations of a group into a direct sum of irreducible representations. The term is often used in the context of two-dimensional conformal field theory where the relevant group is generated by the Virasoro algebra, the relevant representations are the conformal families associated with a primary field and the tensor product is realized by operator product expansions. The fusion rules contain the information about the kind of families that appear on the right-hand side of these OPEs, including the multiplicities.
More generally, integrable models in 2 dimensions which aren't conformal field theories are also described by fusion rules for their charges.
References
Conformal field theory | Fusion rules | Physics | 155 |
4,165,817 | https://en.wikipedia.org/wiki/David%20Cockayne | David John Hugh Cockayne FRS FInstP (19 March 1942 – 22 December 2010) was Professor in the physical examination of materials in the Department of Materials at the University of Oxford and professorial fellow at Linacre College from 2000 to 2009. He was the president of the International Federation of Societies for Microscopy from 2003 till 2007, then vice-president 2007 to 2010.
Cockayne was an electron microscopist who played an important role in the development of weak-beam transmission electron microscopy (TEM), and in the application of high resolution TEM to diamond, fullerenes and semiconductors.
Biography
Cockayne was born in Balham, London, the second of three children of John Henry Cockayne, policeman and later staff manager, and his wife, Ivy, née Hatton. In 1950, when he was 8, the family sailed from Tilbury on the Otranto, bound for Melbourne; their new home was to be in the Geelong area of Victoria. In 1952 they moved to a newly-built house in Geelong, and Cockayne attended a new school, from where he was awarded a scholarship to Geelong Grammar School in 1953, where he excelled in chemistry, physics and mathematics.
In 1961 Cockayne enrolled at the University of Melbourne to read physics; he graduated in 1964 with first-class honours. He went on to do research on electron diffraction for an MSc, again gaining a first in 1966. He was then awarded a Commonwealth Scholarship to read for a DPhil at Magdalen College, Oxford.
David joined the Department of Metallurgy in Oxford in September 1966 to conduct research on electron microscope images of defects in crystal lattices, under the supervision of Dr M J Whelan. He was awarded a DPhil in 1970.
At the age of 32, Cockayne took up the post of director of the University of Sydney Electron Microscope Unit (EMU) in June 1974. He also held the position of associate professor. He was promoted to full professor in 1986, and then to a personal chair (Professor in Physics (Electron Microscopy and Microanalysis)) in 1992. He built up an important research base at Sydney; with David McKenzie he developed a high-precision electron diffraction technique within an electron microscope to study the structure of amorphous materials.
Cockrayne moved back to Oxford in 2000, to take up the post of Professor in the Physical Examination of Materials, at the Department of Materials. He also became Professorial Fellow at Linacre College. In the department of materials he “built up an outstanding electron microscopy group”, and followed up studies started in Sydney on the properties of nanometer-sized crystals (quantum dots) insemiconductor alloys.
The man and his family
“Cockayne was an inspirational lecturer and mentor. He cared deeply about research, teaching, and university administration, and brought lucidity and commitment in equal measure to all three.” […] His interests included “theatre, music, literature, photography, travel, and bushwalking”.
When he was an undergraduate at Trinity College, Melbourne University he met Jean Kerr, who enrolled a year after Cockrayne and was reading French and English honours. She was resident in the next-door hall, and they got to know each other early in 1962 and became close friends in 1964 Shortly before he left for Oxford in September 1966, he proposed to Jean and they announced their engagement. She travelled to England in January 1967, and they were married in Shilton, Oxfordshire on 28 July 1967. The couple had three children: Sophie was born in Oxford in 1973; Tamsin in Sydney in 1975; and James in Sydney in 1977.
David Cockayne died from lung cancer on 22 December 2010. He was cremated in Oxford following a funeral service at the University Church of St Mary the Virgin on 5 January 2011. He wrote his own eulogy to give himself 'the pleasure of knowing what will have been said at my funeral'.
Honours and distinctions
When Cockayne was elected a Fellow of the Royal Society (FRS) in 1999 his certificate of election noted that he was:
References
British physicists
Microscopists
Fellows of the Royal Society
1942 births
2010 deaths
Place of birth missing
Fellows of the Institute of Physics
Presidents of the International Federation of Societies for Microscopy
Fellows of Linacre College, Oxford
Statutory Professors of the University of Oxford
People educated at Geelong Grammar School | David Cockayne | Chemistry | 894 |
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