Karl Guthe Jansky (October 22, 1905 – February 14, 1950) was an American physicist and radio engineer who in April 1933 first announced his discovery of radio waves emanating from the Milky Way in the constellation Sagittarius. He is considered one of the founding figures of radio astronomy.

Early life

Karl Guthe Jansky was born 1905 in what was then the Territory of Oklahoma where his father, Cyril M. Jansky, was dean of the college of engineering at the University of Oklahoma at Norman. Cyril M. Jansky, born in Wisconsin of Czech immigrants, had started teaching at the age of sixteen. He was a teacher throughout his active life, retiring as professor of electrical engineering at the University of Wisconsin.  He was an engineer with a strong interest in physics, a trait passed on to his sons.  Karl Jansky was named after Dr. Karl Eugen Guthe, a professor of physics at the University of Michigan who had been an important mentor to Cyril M. Jansky.

Karl Jansky's mother, born Nellie Moreau, was of French and English descent.  Karl's brother Cyril Jansky Jr., who was ten years older, helped build some of the earliest radio transmitters in the country, including 9XM in Wisconsin (now WHA of Wisconsin Public Radio) and 9XI in Minnesota (now KUOM).

Karl Jansky attended college at the University of Wisconsin where he received his BS in physics in 1927. He stayed an extra year at Madison, completing all the graduate course work for a master's degree in physics except for the thesis. In July 1928 at age 22, he was able to join the Bell Telephone Laboratories, and because of a kidney condition he had since college (which eventually led to his early death), he was sent to the healthier environs of the field station in Holmdel, New Jersey. Bell Labs wanted to investigate atmospheric and ionospheric properties using "short waves" (wavelengths of about 10–20 meters) for use in trans-Atlantic radio telephone service. As a radio engineer, Jansky was assigned the job of investigating sources of static that might interfere with radio voice transmissions.

Radio astronomy

At Bell Telephone Laboratories, Jansky built a directional antenna designed to receive radio waves at a frequency of 20.5 MHz (wavelength about 14.6 meters). It had a diameter of approximately 100 ft. (30 meter) and stood 20 ft. (6 meter) tall. It was mounted on top of a turntable on a set of four Ford Model-T wheels, which allowed it to be rotated in the azimuthal direction, earning it the nickname "Jansky's merry-go-round" (the cost of which was later estimated to be less than $1000).  By rotating the antenna, the direction of a received signal could be pinpointed. The intensity of the signal was recorded by an analog pen-and-paper recording system housed in a small shed to the side of the antenna.

After recording signals from all directions for several months, Jansky eventually categorized them into three types of static: nearby thunderstorms, distant thunderstorms, and a faint static or "hiss" of unknown origin. He spent over a year investigating the source of the third type of static. The location of maximum intensity rose and fell once a day, leading Jansky to initially surmise that he was detecting radiation from the Sun.

After a few months of following the signal, however, the point of maximum static moved away from the position of the Sun. Jansky also determined that the signal repeated on a cycle of 23 hours and 56 minutes. Jansky discussed the puzzling phenomena with his friend, astrophysicist Albert Melvin Skellett, who pointed out that the observed time between the signal peaks was the exact length of a sidereal day; the time it took for "fixed" astronomical objects, such as a star, to pass in front of the antenna every time the Earth rotated. By comparing his observations with optical astronomical maps, Jansky concluded that the radiation was coming from the Milky Way and was strongest (7:10 p.m. on September 16, 1932) in the direction of the center of the galaxy, in the constellation of Sagittarius.

Jansky announced his discovery at a meeting in Washington D.C. in April 1933 to a small audience who could not comprehend its significance. His discovery was widely publicized, appearing in the New York Times of May 5, 1933, and he was interviewed on a special NBC program on "Radio sounds from among the stars". In October 1933, his discovery was published in a journal article entitled "Electrical disturbances apparently of extraterrestrial origin" in the Proceedings of the Institute of Radio Engineers.

If the radio sources were from the stars, the Sun should also be producing radio noise, but Jansky found that it did not. In the early 1930s, the Sun was at an inactive phase in its sunspot cycle. In 1935 Jansky made the suggestion that the strange radio signals may be produced from interstellar gas, in particular, by "thermal agitation of charged particles." Jansky accomplished these investigations while still in his twenties with a bachelor's degree in physics.

Jansky wanted to further investigate the Milky Way radio waves after 1935 (he called the radiation "Star Noise" in the thesis he submitted to earn his 1936 University of Wisconsin Masters degree), but he found little support from either astronomers, for whom it was completely foreign, or Bell Labs, which could not justify, during the depression, the cost of research on a phenomenon that did not significantly affect trans-Atlantic communications systems.

Follow-up
Several scientists were interested in Jansky's discovery, but radio astronomy remained a dormant field for several years, due in part to Jansky's lack of formal training as an astronomer. His discovery had come in the midst of the Great Depression, and observatories were wary of taking on any new and potentially risky projects.

Two men who learned of Jansky's 1933 discovery were of great influence on the later development of the new study of radio astronomy:  one was Grote Reber, a radio engineer who singlehandedly built a radio telescope in his Illinois back yard in 1937 and did the first systematic survey of astronomical radio waves. The second was John D. Kraus, who, after World War II, started a radio observatory at Ohio State University and wrote a textbook on radio astronomy, long considered a standard by radio astronomers.

Death and legacy

Jansky was a resident of Little Silver, New Jersey, and died at age 44 in a Red Bank, New Jersey, hospital (now called Riverview Medical Center) due to a heart condition.

In honor of Jansky, the unit used by radio astronomers for the spectral irradiance of radio sources is the jansky (1 Jy = 10−26 W⋅m−2⋅Hz−1).  The crater Jansky on the Moon is also named after him. The National Radio Astronomy Observatory (NRAO) postdoctoral fellowship program is named after Karl Jansky. Additionally, NRAO awards the Jansky Prize annually in Jansky's honor.  On January 10, 2012, the NRAO announced the Very Large Array (VLA), the radio telescope in Magdalena, New Mexico, would be renamed the Karl G. Jansky Very Large Array in honor of Karl Jansky's contribution to radio astronomy.

A full-scale replica of Jansky's original rotating telescope is located on the grounds of the Green Bank Observatory (, formerly an NRAO site) in Green Bank, West Virginia, near a reconstructed version of Grote Reber's 9-meter dish.

In 1998, the original site of Jansky's antenna  at what is now the Bell Labs Holmdel Complex at 101 Crawfords Corner Road, Holmdel, New Jersey, was determined by Tony Tyson and Robert Wilson of Lucent Technologies (the successor of Bell Telephone Laboratories) a monument and a plaque were placed there to honor the achievement. The monument is a stylized sculpture of the antenna and is oriented as Jansky's antenna was at 7:10 p.m. on September 16, 1932, at a moment of maximum signal caused by alignment with the center of our galaxy in the direction of the constellation Sagittarius.

Jansky noise is named after Jansky, and refers to high frequency static disturbances of cosmic origin. (Cosmic noise).

Asteroid 1932 Jansky is named after him, as is the lunar crater Jansky.

Selected writings

  Reprinted 65 years later as  along with an explanatory preface by W.A. Imbriale, .

See also
Reber Radio Telescope
Astronomical radio source
Radio Astronomy

References

. In particular Chap.1 by Sullivan, "Karl Jansky and the discovery of extraterrestrial radio waves," pp. 3–42.
. In particular Chap. 2.

External links

My Brother Karl Jansky and His Discovery of Radio Waves from Beyond the Earth

Serendipitous Discoveries in Radio Astronomy: Proceedings of a Workshop held at the National Radio Astronomy Observatory, Green Bank, West Virginia on May 4, 5, 6,1983; Honoring the 50th Anniversary Announcing the Discovery of Cosmic Radio Waves by Karl G. Jansky on May 5, 1933. Edited by K. Kellermann and B. Sheets (1983) 321pp

 Encyclopedia of Oklahoma History and Culture – Jansky, Karl
Detective Work Leads to Monument Honoring the Father of Radio Astronomy — Radio Astronomy Celebration at NOKIA Bell Labs

1905 births
1950 deaths
Amateur astronomers
American astronomers
20th-century American physicists
American people of Czech descent
American people of English descent
American people of French descent
Czech-American culture in Oklahoma
People from Little Silver, New Jersey
People from Norman, Oklahoma
Scientists at Bell Labs
Radio astronomers
American electrical engineers
Engineers from New Jersey
20th-century American engineers
Astronomical instrument makers

Karl Guthe Jansky


Molat (pronounced ; ) is a Croatian island in the Adriatic Sea. It is situated near Zadar, southeast from Ist, separated by Zapuntel strait. It has area of .

The settlements on the island are Molat (population 107), Zapuntel (pop. 42) and Brgulje (pop. 48), and they are situated in the interior of the island, and only smaller hamlets are on the seaside. Main industries on the island are agriculture, sheep breeding, fishing and tourism.

Geography
It is composed of lower cretaceous and eocene limestone. Northeastern coast is mostly low and indented with numerous coves but the southwestern coast is largely steep. The relief is characterized by two limestone ridges, separated from each other by the Zapuntel Field (the Bay of Brgulje is its southeastern submerged part). A smaller transversal Molat Field stretches in the southeastern part of the island. It is mostly covered with young forests and underbrush.

History
Molat has been inhabited since the Stone Age. At Ledenice near Zapuntel harbor, in the far north of the island, in Zapuntelsko polje and in the east of the village of Molat, more limestone objects were found from that time.
According to the name of the island it can be concluded that it was inhabited in Neolithic era by pre-Indoeuropean population. This form of name is widespread in the Mediterranean: Mljet, Malta (island of Veli Drvenik, island south of Sicily, hinterland near Zadar).

There are no findings from the Bronze Age. From the Iron Age there were four Illyrian fortresses: Lokardenik, Gračina, Straža and Knežak. Inside the fortress there were objects of roasted ground, limestone items, handguns, food remains (bones, snails and shells). There were also 8 stone tombs (tumulus) found. Pottery vessels imported from southern Italy were found at Gracini near Brgulje.

In Roman times, the local Liburnian population lived quite autochthonously. The existence of the Roman population is evidenced by the toponyms: Karstul, Bavkul, Maknare, Tramerka, Brgulje et al.

Upon arrival, between the seventh and tenth centuries, Croats gradually assimilated the local population. At that time, the first records of the island appeared. The oldest mention is by Constantine VII Porphyrogennetos around 950. The name Melata is mentioned in 1073, 1151, 1195, 1381, etc. Zapuntel was first mentioned in 1450 as the port of Sanpontello, and Brgulje was first mentioned in 1527 when the first Venetian census was made.

The island was donated by Count Desa in 1151 to the monastery of St. Krševan from Zadar. Old maps from 1320 and 1321 mention Molat as the great port of St. Mary (today Lučina), which was an important station on the way from Istria and Osor to Zadar.

After the conquering of Zadar by the Republic of Venice in 1409, Molat became Venetian property and was leased on a yearly basis. For the first 250 years, the lessees changed relatively often. They did not take into account the interests of the population but tried to achieve as much profit as possible, primarily by cutting the forests. Zadar's nobleman, Zuane Piccardi, introduced the ban on cutting wood for the population (even the smallest amount) punishable by a fine of 25 ducats. The Lantane landlord family survived for the longest time, from 1640 until the end of the 19th century when the Abelić family bought the property. For two centuries, with the help of commissioners, dormitories, gastropods and island mulberries, Lantane family extracted quarters, sevenths and tithes in the products. Occasionally they lived in a small, high wall enclosed palace in the village of Molat (built in 1664, after the Second World War until 1990 used as a restaurant, today is neglected). The main product was wine, and they also received oil, grain, beans, lentils, figs, cheese, brandy, skins, fish and others. The supervisors (by Lantana and Abelić) stood at the intersections of rural roads at the time of winding, noting the products brought to the landowners' warehouses.

Island was robbed by riders and various other pirates, and the toponyms of Straža (Guard) and Stražica (Little guard) testify about the attempts of protection. It was recorded that the Turks robbed the island in 1571, and in 1684 they kidnapped and enslaved 20 inhabitants. At the beginning of the nineteenth century, English privateers attacked the island several times; for example, in 1810 they robbed and burned down the house of the Zapuntel parish priest.

In 1666, islanders complained to the General Provost in Zadar about the prerequisite measures of the landowner, but to no avail. Tariffs have become even higher. Between the two world wars, the serfdom of the island was abolished (as evidenced by the memorial plaque on the bell tower of the local church in the village of Molat, 1937). In 1926, the Cultural House was built. In 1933, the Library was founded. In 1937, the island reached its maximum population of 1,083 throughout the recorded history. The population has since decreased due to emigration and urbanization.

During the Second World War in 1942, Italian fascists at Molat established  the Molat concentration camp in the bay of Jaza where 20,000-25,000 prisoners came through of whom 500-1,000 died.

After the Second World War, the population is scattered, fewer people are concerned with tourism, fishing and very little farming. Today, the primary school (opened in 1880) is closed, there are no children on the island.

References

External links

 Molat on kroatien-fewo.net

Islands of Croatia
Islands of the Adriatic Sea
Italian concentration camps
World War II sites in Croatia
Populated places in Zadar County
Landforms of Zadar County

Molat


Mikaela Shiffrin (born March 13, 1995) is an American skier. Her first time at the Winter Olympic Games was during the 2014 Winter Olympics at Sochi, Russia. Before these Olympics, Mikaela had competed in other national and international competitions.

Mikaela Shiffrin was born on March 13, 1995 in Vail, Colorado. Her father, Jeff, skied at Dartmouth College. Her mother, Eileen, came from a Massachusetts family who loved skiing. She has an older brother named Taylor who is also a skier at the University of Denver. When Mikaela was eight her family moved to New Hampshire. Her father got a job at the Dartmouth-Hitchcock Medical Center.

Shiffrin competed in her first international competition at age fifteen. Later that year she joined another international competition and got a gold medal in slalom. By the end of the season she had won four World Cup competitions as well as a slalom title. This made her the youngest person to win a World Cup title. Mikaela Shiffrin was also the youngest ever to win an Olympic gold medal in the slalom. She won one of the five gold medals won by the American Alpine team. In addition to her gold medal, Shiffrin has one gold medal from the world championships and one bronze medal from the Junior World Ski Championships. She has had eight total wins at the World Championships.

References

1995 births
Living people
2014 Winter Olympics
American Olympic gold medalists
American skiers
Sportspeople from Colorado

Mikaela Shiffrin


Swaraj is an Indian historical TV serial. It aired on DD National  from 14 August 2022. With this serial, Doordarshan has once again tried to bring alive the tales of courage of more than 550 freedom fighters. It is a Government of India project and produced by Contiloe Pictures.

Cast

Story teller
Manoj Joshi

Main
Atul Verma as Magatachan
Jason Shah as Vasco da Gama
Gajendra Chauhan as Manvikram
Vinod Kapoor as Alia Rama Ray
Barkha Bisht as  Rani Abbakka
Shruti Bisht as Queen Abbakka's daughter
 Himanshu Bamzai as Subramania Bharati
Arpit Ranka as Shivappa Nayaka
Krish Chauhan as Shivaji Maharaj (child)
Saurav Gokhale as Shivaji Maharaj
Mir Ali as Peshwa Bajirao
Gajendra Chauhan as Samudripad
Arshita Bhatt as Rani Laxmi Bai
Ganesh Venkatram as Velu Thambi
Krip Suri as Marthanda Varma
Amit Pachori as Puli Thevar
Rudra Soni as Wazir Ali
Vineet Kakkar as U Tirot Singh
Benazir Sheikh as Ajijan Bai
Chaitanya Choudhary as Kanoji Angre
Suhasi Dhami as Rani Velu Nachiyar
Himanshu Malhotra as Veerapandha Kattabomman
Ankur Nayyar as Kerala Varma
Megha Chakraborty as Devi Chaudrani
Tabrez Khan as Bhawani Pathak
Ranjit Khanna as Jayi Rajguru
Navneet Malik  as Baxi Jagabandhu
Mukul Harish as Tilka Majhi
Akshay Sethi as Sidhu Murmu
Amit Dolawat as Kanhu Murmu
Jason Tham as Narendrajit
Kushal Gurung as Vibhuvanjit
Harish Agarwal as Maharaj Chandrakirti
Jatin Bhatia as Raj Bali Khan
Jasbir Rawat as Lilambar
Karan Pointer as Mangal Pandey
Ram Yashvardhan as Bakht Khan
Rishiraj Pawar as Udmi Ram
Urvashi Pardeshi as Ratni Devi; Wife of Udmi Ram
Rishita Bhat as Rani Laxmi Bai
Navi Bhangu as Tatya Tope
Krishna Singh Bisht as Tikendrajit Singh
Ashish Dixit as Birsa Munda
Puneet Tejwani as Ajit Singh Sandhu
Asit Redidge as Ajit Singh
Farnaz Shetty as Avantibai
Kapil Arya as Vasudev Balwant Phadke
Shardul Pandit as Dhamodhar Hari Chapekar
Sagar Wahi as Balkrishna Hari Chapekar
Namit Shah as Vasudev Hari Chapekar
Teriya Magar as Young Rani Gaidinluu (16 years old)
Parshvi Gadiya as Child Rani Gaidinliu (13 years)
Himanshu Karki as Jadonang
Sareh Farr as Sister Nivedita
Ribbu mehra as Bhupendra Dutta
Ankit Bathla as Barin Gosh
Gaurav s Bajaj as Shyam Ji Krishna Verma
Gaurav Sharma as Vinayak Damodar Savarkar
Shwetha Munshi as Bhikaji Cama
Rahul Sharma as Madanlaal Dingra
Ujir Basar as Kanailal Dutta
Puneet Raj as  SatendraNath bose
Ajay Chaudhary as Virendranath Chattopadhyay
Randheer Rai as Ras Bihari Bose
Sandeep chatterjee as  Abdul Ghaffar Khan
Aman Gandotra as Young Abdul Ghaffar Khan
Raghav Tiwari as Baikuntha Shukla
Manan Joshi as Raja Mahendra Pratap Singh
Rohit Choudhary as Master Da Surya Sen
Sukriti Kandpal as Veerkanya Pritilata Waddedar
Shresth Kumar as Alluri Sitaram Raju
Priti Gandwani as Usha
Kirtida Mistry as Pushpalatha Das
Naisha Khanna as Kanaklatha Barua
Shagun Pandey as Mahavir Singh
Ashwat Kanth Sharma as Bhagat Singh
Manish Naggdev as Chandra Shekar Azad
Varun Jain as Sukhdev Thapar
Gaurav amlani as Shivaram Rajguru

Recurring
Sourav Sharma as Krishnadevaraya
Vivek Sharma as Bukka Raya
Ishaan Singh Manhas as Nana Saheb Peshwa
Ankur Panchal as Allavuddin Khilji
Vikrant Krishna as Dalpatraya
Chaitra Shetty as Rani Chennabhairavi
Chandan Arora as Virabhadra
Rajputana Aishwarya as Keladi Chennamma
Deepali Kamath as Jija Bai
Satish Jadav as Tanaji
Krishna Choudhary as Malhar Rao Holkar
Rakesh Kukreti as Raja Uday Tevar
Shalini Vishnudev as Edachena Kunkan
Akhil Ojha as Pindiki Bahubalendra
Ananda Neelakanthan as Ettappa Naicker
Ganesh Venkatraman as Velu Thambi Dalava
Girish Soni as Bhagi Seth
Vineet Kakkar as u Tirot
Pankaj Awadhesh Shukla as Lakhan Dubey
Alok Narula ad Bindi Tiwari
Ishaan Manham as Nana Saheb
Krishna Shetty as Tatya Tope
Ram Avana as Sita Ram
Harish Agarwal as Maharaj Chandrakirti
Rohit Singh Rajput as Subhash Chandra Bose
Jeet Bhattacharya as Bhagat Singh
Jasveen Kaur ad Harnam Kaur
Anand Goradia as Lala Har Dayal
Vikas Salgotra as Umrao Singh
Vipul Deshpande as Daulatrao Naik
Alok Bhardwaj as Swami Vivekananda
Rajat Singh as Mahadev Vinayak Ranade
Ajay Mehra as Jawaharlal Nehru
Shivani Saxena as Bhavaneshvari  Devi
Aniruddh Roy as Arbindo Gosh
Sanjeev Sharma as J.C Bose
Nupur Avasti as Sharda Devi
Vishal Jadav /Mayur Bhavasar as LokManya Tilak
Akhil Ojha as Lala Lajpat Ray
Jay Mahadik as Khudiram Bose
Pratik Salvi as Prafulla Chaki
lakshya Vahi as Naren Goswami
Manoj Jaiswal as F.C Dale/ David/Charch Father
Iqbal Azad as Subhash Chandra Bose
Krishna Tiwari as Vishnu Ganesh Pingle
Pramod Ghosh as Mahatma Gandhi
Sachin Ashar as Muhammad Ali Jinnah
Vijayesh Kumar Mishra as Revolutionary Panna Sen
Dhiraj Kumar Rai as Revolutionary Ambika Chakraborty

References

Other websites
Swaraj on IMDb

2020s Indian television series
2022 television series debuts

Swaraj (TV series)


A laisse is a type of stanza, of varying length, found in medieval French literature, specifically medieval French epic poetry (the chanson de geste), such as The Song of Roland.  In early works, each laisse was made up of (mono) assonanced verses, although the appearance of (mono) rhymed laisses was increasingly common in later poems.  Within a poem, the length of each separate laisse is variable (whereas the metric length of the verses is invariable, each verse having the same syllable length, typically decasyllables or, occasionally, alexandrines.

The laisse is characterized by stereotyped phrases and formulas and frequently repeated themes and motifs, including repetitions of material from one laisse to another.  Such repetitions and formulaic structures are common of orality and oral-formulaic composition.  When medieval poets repeated content (with different wording or assonance or rhyme) from one laisse to another, such "similar" laisses are called laisses similaires in French.

References

 Princeton Encyclopedia of Poetry and Poetics. Alex Preminger, ed. Princeton: Princeton University Press, 1965, 1974. "Laisse", p. 436.
 Gerard J. Brault, ed. The Song of Roland: An Analytical Edition. (Pennsylvania State University, 1978).

Stanzaic form
Epic poetry

Laisse


Sam Spruell (born 1 January 1977) is a British actor. He is best known for playing villainous roles in film and television including Oleg Malankov in Taken 3, Finn in Snow White and the Huntsman and Swarm in Doctor Who: Flux. He also appeared in a small role as a military contractor in the 2009 film The Hurt Locker.

Career
His film credits include The Hurt Locker (2008), Defiance (2008), Elizabeth: The Golden Age (2007), London to Brighton (2006), To Kill a King (2003) and K-19: The Widowmaker (2002). Spruell played hit man Jack "The Hat" McVitie in the 2015 film Legend, which told the story of the Kray twins.

His television roles include the recurring cameo of Jason Belling in Spooks (2007 in Episode 6.9 and 2004 in Project Friendly Fire) and the recurring role of Wilkes in P.O.W. (2003).

In 2012, Spruell had a starring role in the film Snow White & the Huntsman, playing the brother to the Evil Queen played by Charlize Theron.

In March 2013 he appeared in one of the lead roles in the BBC One thriller drama series Mayday. He appeared in the television adaptation of The Last Ship later in the year. In 2015, Spruell played Oleg Malankov, the secondary villain in Taken 3. He also played Owen Lynch in the drama series Luther in episode 1.2. He appeared as the character Swarm in the thirteenth series of Doctor Who.

Filmography

External links

British male film actors
1977 births
Living people
British male television actors
21st-century British male actors
20th-century British male actors
British emigrants to the United States
Actors from Southwark

Sam Spruell


The Kenya African National Union is a Kenyan political party.  It ruled for nearly 40 years after Kenya's independence from British colonial rule in 1963 until  2002. It was called Kenya African Union  from 1944 but due to pressure from the colonial government it changed its name to Kenya African Study Union mainly because all political parties were banned in 1939 following the start of the Second World War. In 1946 it called itself  Kenya African Union after Harry Thuku resigned as president due to internal differences between the moderates who wanted peaceful negotiations and the militants who wanted to use force.  The militants formed The forty Group, which later became the Mau Mau. The president was then James Gichuru. After him was Jomo Kenyatta in 1947. The organisation was banned by the colonial government from 1952 to 1960. It was set up again by James Gichuru in 1960 and renamed KANU on 14 May 1960 when it joined  with Tom Mboya's Kenya Independence Movement.

References

Political parties in Kenya

Kenya African National Union


Horst Ludwig Georg Erich Wessel (9 October 1907-23 February 1930) was a member of the SA, of the National Socialist German Worker's Party from 1926-1930 . In 1930, he was killed by a communist. As he had written the Horst Wessel-Lied, the party made him into a martyr and hero . Horst Wessel was born in 9 October 1907 in the city of Bielefeld in the Kingdom of Prussia in the German Empire (now ; North Rhine-Westphalia) . He joined the National Socialist (Nazi Party) in 1926 at the age of 19 he later became Sturmfuhrer of the SA the same year. In February 1930 he was killed by the Communist Party of Germany in Berlin (aged ; 22) .

1907 births
1930 deaths

Horst Wessel


The ichthys or ichthus (/ˈɪkθəs/), from the Greek ikhthū́s (ἰχθύς, 1st cent. AD Koine Greek pronunciation: [ikʰˈtʰys], "fish") is a symbol consisting of two intersecting arcs, the ends of the right side extending beyond the meeting point so as to resemble a fish.

In the Gospels
Fish are mentioned and given symbolic meaning several times in the Gospels. Several of Jesus' 12 Apostles were fishermen. He commissions them with the words "I will make you fishers of men". (Mark 1: 16-18). Having been resurrected, Jesus was given grilled fish in Luke 24:41-43.
Acronyms
Symbols

Ichthys (symbol)


Toby Gold (born 27 September 1994) is an English wheelchair racer. He is classified as a T33 athlete and competes primarily in sprint events, winning the 100m gold in the 2016 European Championships and silver at the 2016 Paralympic Games.

Personal history
Gold was born in England in 1994. He was educated at Wimbledon College and St Mary's University, Twickenham, both Roman Catholic schools. He studied Sports Science at St Mary's.

Athletics career
Gold first became involved in athletics after being spotted playing wheelchair basketball in 2011. He was invited to try out at Kingsmeadow Athletics Stadium in Kingston, and subsequently joined the wheelchair training squad. By 2012 he was classified as a T33 disability athlete and began competing at national meets, mainly in sprint events.

During 2013 and 2014 Gold kept competing at national competitions winning gold medals at IWAS World Junior Games. In May 2014 he travelled to Notwill in Switzerland to compete at his first overseas event, where he collected gold in both the 100m and 200m events. Gold first represented Great Britain in a major international meet at the 2015 IPC Athletics World Championships in Doha.

Due to the absence of any 200m and 400m events, Gold only contested the 100m race, where he finished third to collect the bronze medal. The following year, in the buildup to the 2016 Summer Paralympics, Gold appeared at the European Championships in Grosseto. In a limited field, Gold finished first, beating fellow British athlete Dan Bramall into second place. Gold's finishing time of 17.64 was more than a second a half faster than his result the year previous in Doha. Gold won a Silver Medal at the 2016 Paralympic Games.

References

Living people
1994 births
English male wheelchair racers
Alumni of St Mary's University, Twickenham
People educated at Wimbledon College

Toby Gold


Public Safety Canada (PSC; , SPC; PSP), legally incorporated as the Department of Public Safety and Emergency Preparedness (PSEPC), is the department of the Government of Canada responsible for (most) matters of public safety, emergency management, national security, and emergency preparedness in Canada.

The department is responsible to Parliament through the minister of public safety and minister of emergency preparedness.

History
Prior to 1988, the agency responsible for the "public safety" portfolio was known as Emergency Preparedness Canada, which was created under the auspices of the Department of National Defence. In 1988, the Department of Public Safety and Emergency Preparedness was established by the Emergency Preparedness Act.

With the purpose of creating a single entity with responsibility for ensuring public safety in Canada, the Department of Public Safety and Emergency Preparedness was created in December 2003 during a reorganization of the federal government. Created as a direct result of lessons learned from the September 11 attacks on the United States in 2001, the department is in many ways similar to the U.S. Department of Homeland Security; it does not cover the protection of maritime sovereignty (which is covered by the Canadian Forces, Transport Canada, and Fisheries and Oceans Canada), and it does not have general jurisdiction over immigration (it took over immigration enforcement functions most visibly at borders and ports of landing, but the separate department Immigration, Refugees and Citizenship Canada manages application and screening, settlement services, and naturalization).

PSEPC became legally established when the Department of Public Safety and Emergency Preparedness Act came into force on 4 April 2005.

Governance and organization

The legal authority of Public Safety Canada is enabled through the Emergency Management Act (2007) and the Department of Public Safety and Emergency Preparedness Act, S.C. 2005, c. 10, which came into force on 4 April 2005 during the Martin government. The department became legally established when this Act was given Royal Assent.

PSC has 12 regional offices, which are located across the country and are organized into 5 regions:

 Atlantic — St-John's, NL (The John Cabot Building); Charlottetown, PE (National Bank Tower); Dartmouth, NS (Eric Spicer Building); and Fredericton, NB
 Quebec and Nunavut — Montreal, QC (Square-Victoria Street)
 Ontario — Toronto, ON (Bloor Street)
 Prairies and Northwest Territories — Winnipeg, MB (Broadway); Regina, SK ( Regina); Edmonton, AB (Baker Centre Building); and Yellowknife, NT (Greenstone Building)
 British Columbia and Yukon — Burnaby, BC (Production Way); and Saanichton, BC.

Spending
Together, the agencies of Public Safety Canada have an annual budget of more than CA$9 billion and over 66,000 employees working across the country.

PSC's planned spending for the 2023-24 fiscal year is $2.6 billion; this can be broken down by core responsibility:

 National security: $30.1 million,
 Community safety: $731 million,
 Emergency management: $1.81 billion,
 Internal services: $68.7 million.

Public Safety portfolio
Most of the department comprises organizations that were previously placed under the Department of Solicitor General of Canada, however the reorganization of several federal departments and ministries added the Canada Border Services Agency to the portfolio, after the two streams of the former Canada Customs and Revenue Agency were split in 2003. In addition, the Office of Critical Infrastructure Protection and Emergency Preparedness (OCIPEP) from the Department of National Defence was also brought into the department.

In addition to the department, there are five agencies and three review bodies within the Public Safety portfolio headed by the Minister of Public Safety.

Organizations
Agencies:
Canada Border Services Agency
Canadian Security Intelligence Service
Integrated Terrorism Assessment Centre
Correctional Service of Canada
Parole Board of Canada
Royal Canadian Mounted Police
Canadian Firearms Program
 Canadian Police College
Canadian Police Information Centre
Criminal Intelligence Service Canada
Integrated National Security Enforcement Teams
Parliamentary Protective Service (through an agreement with the speakers of the House of Commons and Senate)
Review bodies:
Civilian Review and Complaints Commission for the RCMP
 Office of the Correctional Investigator
 RCMP External Review Committee
Other units:
Canadian Cyber Incident Response Centre
National Search and Rescue Secretariat

Core responsibilities
The core responsibilities of Public Safety Canada include:

 National security — developing policy, legislation, and programs to support Canada's capacity to respond to, and counter, national security threats directed against Canadians, Canada's critical infrastructure, and Canada's cyber systems.
 PSC administers the Passenger Protect Program (PPP) — an aviation security program akin to the "No Fly List," which prevents those deemed as risks from boarding an aircraft or subjects them to additional screening measures.
 PSC plans to launch the Financial Crime Coordination Centre (FC3; formerly known as the Anti-Money Laundering Action, Coordination and Enforcement Team, or ACE) — a centre whose operations are intended to focus on "coordinating support for anti-money laundering and anti-terrorist financing operational partners."
 Community safety — providing national coordination to "help Canadian communities and stakeholders respond to crime and build community resilience, promote the safety and security of Canadian communities and institutions, enhance the integrity of Canada's borders, and support the provision of policing services to Indigenous communities." In short, community safety includes crime prevention, law enforcement and policing, serious and organized crime, border policy, corrections, and Indigenous policing. Public Safety Canada:
 provides funding to the Canadian Centre for Child Protection — a charitable organization that operates Cybertip.ca, a tip-line for reporting the online sexual exploitation of children.
 provides funding to the Canadian Centre to End Human Trafficking — an organization that operates a multilingual, 24/7 toll-free Canadian Human Trafficking Hotline.
 supports the coming-into-force of the remaining provisions under former Bill C-71, An Act to amend certain Acts and Regulations in relation to firearms.
 delivers the First Nations Policing Program — a programme supporting police services in First Nations and Inuit communities
 Emergency management — strengthening an all-hazards approach to national emergency management in order to 'help prevent, mitigate, prepare for, respond to and recover from emergency events. Public Safety Canada:
 works to advance a Public Safety Broadband Network (PSBN) — a secure high-speed wireless data communications network that can be used by emergency responders and public safety personnel to communicate with each other in emergency situations and during day-to-day operations. In 2017-2018, the Canadian government introduced a Federal PSBN Task Team to consult provincial/territorial and municipal governments, first responders, the private sector, and others on implementation models for a PSBN in Canada.
 helps to support the National Public Alerting System (NPAS; brand name: Alert Ready) — a system that provides emergency management organizations across Canada with the ability to quickly warn the public of imminent or unfolding hazards to life.
 support the long-term policy of its program for Heavy Urban Search and Rescue (HUSAR) — a specialized form of urban search and rescue.
 leads Canada's engagement with the International COSPAS-SARSAT Programme Agreement — a satellite-based search-and-rescue system.
 supports and reviews the Disaster Financial Assistance Arrangements (DFAA) — a federal government program that provides financial assistance to provincial/territorial governments following large-scale natural disasters.

Other operations and initiatives

Canada Centre for Community Engagement and Prevention of Violence
The Canada Centre for Community Engagement and Prevention of Violence (Canada Centre) leads the Canadian government's efforts to "counter radicalization to violence." Rather than managing or advising on individual cases, it addresses the issue in terms of broad strategy. It is located at Public Safety Canada headquarters in Ottawa.

The Minister of Public Safety was given the mandate over the Centre in 2015; the federal budget the following year allocated $35 million over five years to establish and support the Centre, in addition to $10 million per year on-going. The Centre was officially launched in 2017.

In terms of international efforts, the Canada Centre closely collaborates with partners in the Five Eyes (United States, United Kingdom, Australia, New Zealand), the Group of Seven (G7), and the European Union. The Centre also actively participates in multilateral forums such as the United Nations and the Global Counterterrorism Forum (GCTF), as well as collaborating with the Institute for Strategic Dialogue, the Hedayah Center, and the Centre for Research and Evidence on Security Threats (CREST).

The Centre administers the Community Resilience Fund (CRF), a system for supporting "partnerships in countering radicalization to violence in Canada," providing funding to organizations towards engagement (e.g., research, cooperation, engaging communities, etc.) with the issue.

As of 2019‑2020 onward, the Fund has been promised $7 million available each year for existing and new projects. Through the Fund, the Canada Centre has supported the Centre for the Prevention of Radicalization Leading to Violence, located in Montréal, in conducting research on "better understanding risk and protective factors within families of individuals who radicalize to violence and also the role families and communities can play in mitigating radicalization to violence."

National Strategy on Countering Radicalization to Violence
On 11 December 2018, the Canada Centre launched the "National Strategy on Countering Radicalization to Violence," which "explains radicalization to violence and the destructive and harmful behaviours involved, and outlines the Government of Canada's approach and key priorities in countering and preventing radicalization to violence."

The National Expert Committee on Countering Radicalization to Violence ensures that the Canada Centre's efforts to implement the recently launched National Strategy on Countering Radicalization to Violence will help meet the Strategy's three priorities: building, sharing and using knowledge; addressing radicalization to violence in the online space; and supporting interventions. Its members includes:

 Nina Krieger — Executive Director at the Vancouver Holocaust Education Centre.
 Jaspreet Khangura — Emergency physician (FRCPC) at the Royal Alexandra Hospital and Northeast Community Health Centre in Edmonton, Alberta.
 Rizwan Mohammad — a civic engagement coordinator
 Irfan Chaudhry — a hate crimes researcher and the Director of the Office of Human Rights, Diversity and Equity at MacEwan University.
 Shelly Whitman — Executive Director of the Roméo Dallaire Child Soldiers Initiative

Canadian Disaster Database
The Canadian Disaster Database (CDD) publicly-accessible web-based repository that tracks significant disaster events, describing (1) where and when a disaster occurred; (2) the number of injuries, evacuations, and fatalities; and (3) an estimate of the costs. It contains detailed historical information on over 1,000 natural and human-made disasters (such as technological and conflict events, excluding war) that have taken place since 1900 in Canada or abroad and that have directly affected Canadians.

The events that are tracked conform to the "Emergency Management Framework for Canada's" definition of a disaster and meet one or more of the following criteria:

 10 or more people killed;
 100 or more people affected/injured/infected/evacuated or homeless;
 an appeal for national/international assistance;
 historical significance; and/or
 significant damage/interruption of normal processes such that the community affected cannot recover on its own.

Get Prepared
The "72 Hours...Is Your Family Prepared?" campaign (or the 72 Hours campaign) is a social-marketing program on emergency preparedness meant to motivate Canadians to (1) "know the risks in their community;" (2) "make an emergency plan;" and, (3) "get an emergency kit." The idea is to ensure that Canadians are prepared to survive on their own for at least the first 72 hours of an emergency, if there ever were one.

The campaign was launched in 2006 by Public Safety Canada in collaboration with the Canadian Red Cross, St. John Ambulance, and The Salvation Army.

The campaign includes various publications and promotional materials, and a dedicated website called GetPrepared.ca, among other things. Also as part of this campaign, Public Safety Canada coordinates a yearly national event called Emergency Preparedness Week (EP Week), which takes place during the first full week of May and supports emergency preparedness-related activities at the local level.

Canada-United States Cross-Border Crime Forum
The Canada-United States Cross-Border Crime Forum (CBCF) is a joint Ministerial forum that brings together senior law enforcement and justice officials from several organizations in Canada and the United States.

Hosted by Public Safety Canada, Justice Canada, the U.S. Department of Justice, and the U.S. Department of Homeland Security, the CBCF addresses issues of transnational crime, such as organized crime, counter-terrorism, smuggling, economic crime. CBCF was formed in 1997 with an operational focus, originally addressing smuggling across the eastern regions of both countries.

The main Canadian participants include:

 Public Safety Canada
 Department of Justice Canada
 Royal Canadian Mounted Police
 Canada Border Services Agency
 Global Affairs Canada
 Public Prosecution Service of Canada

The main American participants include:

 Department of Justice
 Department of Homeland Security
 U.S. Attorneys
 Federal Bureau of Investigation
 Bureau of Alcohol, Tobacco, Firearms and Explosives
 Drug Enforcement Administration
 U.S. Immigration and Customs Enforcement
 U.S. Customs and Border Protection
 U.S. Coast Guard
 U.S. Department of State

See also

 Interagency Volcanic Event Notification Plan
 List of emergency management agencies in Canada
Emergency Management BC
Emergency Management Ontario
Ministère de la sécurité publique (Quebec)
 Canadian Air Carrier Protection Program
 Ministry of Community Safety and Correctional Services (Ontario)
 Toronto Office of Emergency Management
 Minister of Justice (Canada)
 Public safety
 Federal Emergency Management Agency (FEMA) - United States

References

External links
Official website
www.getprepared.gc.ca

2003 establishments in Canada
Federal departments and agencies of Canada
Emergency management in Canada
Ministries established in 2003
Canada

Public Safety Canada


Automatic identification and data capture (AIDC) refers to the methods of automatically identifying objects, collecting data about them, and entering them directly into computer systems, without human involvement. Technologies typically considered as part of AIDC include QR codes, bar codes, radio frequency identification (RFID), biometrics (like iris and facial recognition system), magnetic stripes, optical character recognition (OCR), smart cards, and voice recognition. AIDC is also commonly referred to as "Automatic Identification", "Auto-ID" and "Automatic Data Capture".

AIDC is the process or means of obtaining external data, particularly through the analysis of images, sounds, or videos. To capture data, a transducer is employed which converts the actual image or a sound into a digital file. The file is then stored and at a later time, it can be analyzed by a computer, or compared with other files in a database to verify identity or to provide authorization to enter a secured system. Capturing data can be done in various ways; the best method depends on application.

In biometric security systems, capture is the acquisition of or the process of acquiring and identifying characteristics such as finger image, palm image, facial image, iris print, or voiceprint which involves audio data, and the rest all involve video data.

Radio-frequency identification is relatively a new AIDC technology, which was first developed in the 1980s. The technology acts as a base in automated data collection, identification, and analysis systems worldwide. RFID has found its importance in a wide range of markets, including livestock identification and Automated Vehicle Identification (AVI) systems because of its capability to track moving objects. These automated wireless AIDC systems are effective in manufacturing environments where barcode labels could not survive.

Overview of automatic identification methods

Nearly all the automatic identification technologies consist of three principal components, which also comprise the sequential steps in AIDC:
 Data encoder. A code is a set of symbols or signals that usually represent alphanumeric characters. When data are encoded, the characters are translated into machine-readable code. A label or tag containing the encoded data is attached to the item that is to be identified.
 Machine reader or scanner. This device reads the encoded data, converting them to an alternative form, typically an electrical analog signal.
 Data decoder. This component transforms the electrical signal into digital data and finally  back into the original alphanumeric characters.

Capturing data from printed documents
One of the most useful application tasks of data capture is collecting information from paper documents and saving it into databases (CMS, ECM, and other systems). There are several types of basic technologies used for data capture according to the data type:

OCR – for printed text recognition
ICR – for hand-printed text recognition
OMR – for marks recognition
OBR – for barcodes recognition
BCR – for bar code recognition
DLR – for document layer recognition

These basic technologies allow extracting information from paper documents for further processing in the enterprise information systems such as ERP, CRM, and others.

The documents for data capture can be divided into 3 groups: structured, semi-structured, and unstructured.

Structured documents (questionnaires, tests, insurance forms, tax returns, ballots, etc.) have completely the same structure and appearance. It is the easiest type for data capture because every data field is located at the same place for all documents.

Semi-structured documents (invoices, purchase orders, waybills, etc.) have the same structure, but their appearance depends on several items and other parameters. Capturing data from these documents is a complex, but solvable task.

Unstructured documents (letters, contracts, articles, etc.) could be flexible with structure and appearance.

The Internet and the future

Advocates for the growth of AIDC systems argue that AIDC has the potential to greatly increase industrial efficiency and general quality of life. If widely implemented, the technology could reduce or eliminate counterfeiting, theft, and product waste, while improving the efficiency of supply chains. However, others have voiced criticisms of the potential expansion of AIDC systems into everyday life, citing concerns over personal privacy, consent, and security.

The global association Auto-ID Labs was founded in 1999 and is made up of 100 of the largest companies in the world such as Walmart, Coca-Cola, Gillette, Johnson & Johnson, Pfizer, Procter & Gamble, Unilever, UPS, companies working in the sector of technology such as SAP, Alien, Sun as well as five academic research centers. These are based at the following Universities; Massachusetts Institute of Technology in the USA, the University of Cambridge in the UK, the University of Adelaide in Australia, Keio University in Japan, and ETH Zurich, as well as the University of St. Gallen in Switzerland.

The Auto-ID Labs suggests a concept of a future supply chain that is based on the Internet of objects, i.e., a global application of RFID. They try to harmonize technology, processes, and organization. Research is focused on miniaturization (aiming for a size of 0.3 mm/chip), reduction in the price per single device (aiming at around $0.05 per unit), the development of innovative applications such as payment without any physical contact (Sony/Philips), domotics (clothes equipped with radio tags and intelligent washing machines), and sporting events (timing at the Berlin Marathon).

AIDC 100
AIDC 100 is a professional organization for the automatic identification and data capture (AIDC) industry. This group is composed of individuals who made substantial contributions to the advancement of the industry. Increasing business's understanding of AIDC processes and technologies are the primary goals of the organization.

See also

 Automated species identification
 Automatic equipment identification
 Automatic number-plate recognition
 Auto-ID Labs
 Data privacy
 Device management
 Digital Mailroom
 Face recognition
 Field Service Management
 Mobile Enterprise
 Mobile Asset Management
 Smart data capture
 Ubiquitous computing
 Ubiquitous Commerce

References

Encodings
Multimodal interaction
Human–computer interaction
Radio-frequency identification


John Rous (c. 1411/20 – 24 January 1492) was an English historian and antiquary, most noted for his Historia Regum Angliae ("History of the Kings of England"), which describes ancient British and English rulers from Brutus to King Henry VII. His historical work is now considered to have "displayed no critical faculty" and to have made credulous the "imaginative embellishments (of) the myths of Geoffrey of Monmouth." However his Rous Roll and Warwick Roll are noted for their historically important illustrations, often credited to Rous's hand but not with certainty.

Origins
Rous was born at Warwick, probably in 1420, though this is uncertain. He was the son of Geoffrey Rous of Warwick, a younger son of Thomas Rous of Brinklow, by his wife Margaret Fyncham, a daughter of Richard Fyncham, both of armigerous gentry families.

Career
He was educated at Oxford University. He entered holy orders, remaining in the vicinity of Warwick for most of his clerical career but making some travels to study archives for his historical research. He spent most of his career in the service of the Yorkist dynasty. He was chaplain of the chapel of Guy's Cliffe during the reign of King Richard III (1483-1485) and was a canon of the Collegiate Church of St Mary, Warwick.

Works

Rous Roll

He was responsible for creating the "Rous Roll", written during the reign of Richard III (1483–1485), which presents a pro-Yorkist version of contemporary English history. In it he praises Richard as a "good lord" who punished "oppressors of the commons". However, he reversed his position dramatically in his later Historia Regum Angliae written in the following reign under Henry VII (1485–1509), Richard's deposer, in which he portrays Richard as a freakish individual born with fully-formed teeth and shoulder-length hair after having been in his mother's womb for two years, and as an adult with a stunted and distorted body with one shoulder higher than the other. In the later work Rous also attributes the 1471 murder of King Henry VI to Richard, and claims that he poisoned his own wife. The Rous Roll also contains details of the prophesies of the anchoress Emma Rawghton who lived until 1436.

Warwick Roll
The "Warwick Roll" is a family chronicle of the Beauchamp family, concerned mainly with the life of Richard Beauchamp, 13th Earl of Warwick (1382-1439), a contemporary of Rous.

Historia Regum Angliae
In his Historia Regum Angliae ("History of the Kings of England") Rous was mainly interested in antiquarian details of social life and the development of scholarly institutions. For example in his life of King Henry V (1413-1422) Rous describes that king's educational history and his social projects but omits to mention the Battle of Agincourt, the central event in his reign, merely noting that he "campaigned in France" and was "renowned for his military skills".

Other works
Rous appears to have written a number of other works about  Warwickshire local history and histories of the Universities of Oxford and Cambridge. He also wrote a treatise on giants whom he supposed lived after the Great Flood, but most of these works are now lost.

Death
He died on 24 January 1492, aged 81 according to some sources, and was buried in the Collegiate Church of St Mary, Warwick, to which he bequeathed his library, directing that a special room to house it be built.

References

External links

1491 deaths
English chroniclers
English antiquarians
15th-century antiquarians
People from Warwick
Year of birth uncertain
English male non-fiction writers

John Rous (historian)


WD repeat-containing protein 36 is a protein that in humans is encoded by the WDR36 gene.

This gene encodes a member of the WD repeat protein family. WD repeats are minimally conserved regions of approximately 40 amino acids typically bracketed by gly-his and trp-asp (GH-WD), which may facilitate formation of heterotrimeric or multiprotein complexes. Members of this family are involved in a variety of cellular processes, including cell cycle progression, signal transduction, apoptosis, and gene regulation. Mutations in this gene have been associated with adult-onset primary open-angle glaucoma (POAG).

References

Further reading

WDR36


Terry Pettus Park is a  park located in Seattle, Washington, on the eastern shoreline of Lake Union at Fairview Avenue E. and E. Newton Street. It includes shoreline access and a public float.

The park is named after Terry Pettus, an activist who played a crucial role in saving Lake Union's houseboats.

Notes

External links

Terry Pettus Park, Seattle Parks and Recreation
Historylink essay on Terry Pettus

Parks in Seattle

Terry Pettus Park


Mei (from ) is a genus of duck-sized troodontid dinosaur first unearthed by paleontologists from the Yixian Formation in Liaoning, China in 2004. Mei lived during the Early Cretaceous period. The binomial name of its only species, Mei long (Chinese 寐 mèi and 龍 lóng), means sleeping dragon.

Description

Mei is a troodontid, a group of small, bird-like, gracile maniraptorans. All troodontids have many unique features of the skull, such as closely spaced teeth in the lower jaw, and large numbers of teeth. Troodontids have sickle-claws and raptorial hands, and some of the highest non-avian encephalization quotients, meaning they were behaviourally advanced and had keen senses. The type fossil is a young juvenile about  long, complete and exceptionally well preserved in three-dimensional detail, with the snout nestled beneath one of the forelimbs and the legs neatly folded beneath the body, similar to the roosting position of modern birds. This posture provides another behavioral link between birds and dinosaurs. The chemistry of the matrix stone and the resting pose indicate the living animal was probably buried instantly in volcanic ash. A second specimen, DNHM D2154, was also preserved in a sleeping posture. Although DNHM D2154 exhibits several juvenile-like features including free cervical ribs, unfused frontals and nasals, and a short snouted skull, other attributes, full fusion of all neurocentral synostoses and the sacrum, and dense exteriors to cortical bone, suggest a small, mature individual. Microscopic examination of tibia and fibula histology confirms maturity and suggests an individual greater than two years old with slowed growth. Mei is notable as a distinct species of troodontid based on several unique features, including extremely large nares. It is most closely related to the troodontid Sinovenator, which places it near the base of the troodontid (bird like) family.

As a basal troodontid, unlike advanced troodontids, it has a bird like hip structure shared with many advanced maniraptorans.

Palaeoecology
Mei lived in the Early Aptian stage of the Cretaceous period, about 125.8 million years ago. At this time, the Liaoning area was dominated by numerous volcanoes in a landscape that was covered in coniferous forest, with an understory of ferns and other plants like large horsetails. Several other trees were present, such as ginkgos and araucarias. Some of the earliest flowering plants were also found here. Rivers and streams coming down from the flanks of the volcanoes fed into lakes in the valleys.

There were many species of small birdlike theropod dinosaurs living in the area, although most of them were slightly larger than Mei. This probably led to a lot of niche partitioning.  There were only five or six species of herbivorous non-theropod dinosaurs, however, and a large and varied fauna of early mammals and pterosaurs. The apex predator was the 9-meter-long tyrannosauroid Yutyrannus, which would have preyed on the two or more species of sauropod. Often, volcanoes erupted, entombing animals in ash and suffocating others with carbon monoxide, which accounts for the high level of preservation of fossils.

Mei probably fed on small lizards and insects on the forest floor. It probably climbed trees as well to shelter from larger predators, and was probably not omnivorous. Judging by the length of the legs, it was a fast runner. Nothing is known about its nesting habits.

When the first fossil of Mei was discovered, scientists were charmed to see the fossil in a birdlike sleeping posture. Mei long means 'sleeping dragon' in Chinese. The animal had probably died from carbon monoxide poisoning, then became entombed in ash.

See also

 Timeline of troodontid research
 Changmiania

References

External links
 Mei long at the American Museum of Natural History

Troodontids
Aptian life
Valanginian life
Early Cretaceous dinosaurs of Asia
Cretaceous China
Fossils of China
Yixian fauna
Paleontology in Liaoning
Fossil taxa described in 2004
Taxa named by Xu Xing
Taxa named by Mark Norell

Mei long


Bombshell Rocks is a Swedish band that was founded in 1995, in Västerås, Sweden.

History
The group was formed in 1995 with a line-up of singer Mårten Cedergran, guitarists Richard Andersson and Sami Korhonen, bassist Mathias Lindh, and drummer Chrille Hermansson, and had performed under its original band name, Down and Out, before changing it to Bombshell Rocks.

In early 1996, Bombshell Rocks released an EP in form of a mini six-track album, Who's the Real Bastard. During this period, Thomas Falk became the band's drummer and Christian Määttä the band's guitarist, after Chrille and Sami left the band. In 1997, Bombshell Rocks released an EP, Going Up Going Down, on their own label Noiseline Rec. Sidekicks Records signed Bombshell Rocks the following year, and released the Underground Radio MCD.

In 1999 Bombshell Rocks released its debut album Street Art Gallery. Shortly after this debut, Richard Andersson was replaced by Ola Hjelmberg when he left the band. During this period, Sweden's biggest punk-rock label Burning Heart Records took notice of their Rancid-influenced street punk sound and short after the band made a deal with them, resulting in releases on American label Epitaph Records, and Japanese label JVC . After an extensive touring phase e.g. with Millencolin, Dropkick Murphys, 59 Times The Pain, US Bombs, and many more in Europe, USA and Canada they entered in 2000 the studio to prove their debut wasn't a one-shot.

On Cityrats And Alleycats Bombshell Rocks went on with their raw, fast, and highly energetic punk rock but this time the production was quite better. Maybe a result of their decision to work with the same guys as they worked with on Street Art Gallery: Mieszko Talarczyk (Nasum) and Mathias Färm (Millencolin) as engineers and producers. Tours and support for main acts like Blink 182, Millencolin and The Offspring followed.

In 2002 they recorded their 3rd studio album From Here And On at the famous Tonteknik Studio in Umeå, Sweden (where Refused laid down their classic The Shape Of Punk To Come) and followed their path of political motivated punk rock anthems. At this time Ola Hjelmberg had left the band and the original guitar player Richard Anderson returned to the band.

When Mårten Cedergran decided to focus on a career as a tattoo artist and left the band in 2003, guitarists Christian Määttä and Richard Andersson took over the vocals and continued as a four-member band. Bombshell Rocks then released The Conclusion in 2005 on Finnish label Combatrock Industry, US label Sailorsgrave Records and UK label Household Name Rec. The band also toured Japan for the first time in 2007 and 2008 with the release of this record.

In 2012 the band announced that Mårten Cedergran was back in the band, once again as the lead vocalist and lead frontman. They did their first show together after a decade on Millencolin 20 Year Festival in Örebro, Sweden. The band recently announced on their website that they will play Brazil in December 2013 for the first time and also that a new EP will be released on San Francisco based label Pirates Press Records. The band then followed up with a new full-length album in 2014 on Burning Heart and Pirates Press Records called "Generation Tranquilized".  Then in 2015 another 7" called "This Time Around".

Discography

Studio albums
Street Art Gallery (1999)
Cityrats And Alleycats (2001)
From Here And On (2003)
The Conclusion (2005)
Generation Tranquilized (2014)

EPs
Who's The Real Bastard (1996)
Going Up Going Down (1997)
Underground Radio (1998)
The Will The Message (1999)
Madhouse (2000)
Radio Control (2001)
Love For The Microphone (2004)
Scars And Tattoos (7", Pirates Press Records, 2014)
This Time Around (7", Burning Heart/Pirates Press 2014)

Music videos
 "The Will The Message" (1999)
 "On My Way" (2003)
 "Bloodbrothers" (2005)
 "Move Rhythm City" (2008)

References

External links
Bombshell Rocks Official Website
Bombshell Rocks On MySpace
Bombshell Rocks On Last.FM
Household Name Records
Sailor's Grave Records
Combat Rock Industries
Burning Heart Records

Street punk groups
Musical groups established in 1995
Burning Heart Records artists
Swedish punk rock groups

Bombshell Rocks


Houghs Neck  is a one-square-mile (2.6 km2) peninsula in Quincy, Massachusetts. It is surrounded by Quincy Bay, Hingham Bay and Rock Island Cove. It is lined by Perry Beach, which runs along Manet Avenue; Nut Island, which is just beyond Great Hill at the very end of the peninsula; and Edgewater Drive.

Houghs Neck is commonly referred to by locals as "The Neck" or "God's Country," and its residents as "Neckahs" ("Neckers") or "Neck Birds".

The Hough's Neck Pumping Station (or the "Pumpy" by the locals) is also part of the Boston Harbor Islands, along with Racoon Island, which can be walked to at low tide. Raccoon Island covers .3 sq. miles.

In 1778, founding father John Adams left for a diplomatic mission to France from Houghs Neck instead of Boston, to evade capture by the British.

History
Houghs Neck is named for Atherton Hough, previously mayor of Boston, England, who was granted the land in 1636 as a farm and orchard. The neighborhood's elementary school is also named for Atherton Hough. The peninsula has been called the "flounder capital of the world" and once had six boat rental businesses geared toward catching the bottom dwelling winter flounder that spent the cold weather months in Boston Harbor. Due to its proximity to Boston and its coastline, it was considered a summer resort from the late 19th century well into the 20th Currently, Houghs Neck is a thickly settled neighborhood.

Transportation
Sea Street and Manet Avenue are major thoroughfares in the neighborhood. The Massachusetts Bay Transportation Authority provides service to Houghs Neck with the 216 bus route, which links this area to the Red Line train station in Quincy Center.

References

Peninsulas of Massachusetts
Quincy, Massachusetts
Landforms of Norfolk County, Massachusetts

Houghs Neck


D.W. Field Park is a municipal park managed by the parks department of the city of Brockton, Massachusetts. The park consists of  of fields, woodlands, and water bodies in northern Brockton and southern Avon, Massachusetts.  It was created in 1925 as a bequest from Brockton businessman Daniel W. Field. Its landscape is dominated by a chain of seven water bodies, all but one of which are man-made, impounding Beaver Brook. The oldest of them, Cross Pond, was created in the 1790s; these lakes, ponds, and reservoirs, were, with one exception, created before the park was laid out, and served either agricultural or industrial purposes. Waldo Lake was created in the 1930s as part of the park's design.

Access to the park's interior is via a narrow road  long that winds through the grounds, providing access to its major features.  This circuit road is accessible from the surrounding public roadways at a number of points, with gates built from locally gathered fieldstone. There is no formalized network of pedestrian paths. As a result, activities tend to be concentrated at the places where there are parking facilities, resulting in some environmental and scenic degradation.

The park's most prominent landmark is a fieldstone observation tower, built at the park's high point, known as Indian Cave Hill or Tower Hill. It was built in 1928 from fieldstones gathered from the park grounds. Inside 90 steps, approximately 18 per landing, lead to an observation deck with a visage as far as Blue Hills in all directions.  The park is open everyday dawn til dusk;  the tower is officially open 1 day a year during Towerfest, early October, Columbus Day weekend.

At the foot of Tower Hill is a concrete pad, in which are embedded Daniel Field's handprints and footprints, and the inscription "Please Enjoy, Do Not Destroy D.W. Field Park." The other major structure in the park is the gatehouse of the Brockton Reservoir, which was built in the 1880s. The park also includes an eighteen-hole golf course.

The park was listed on the National Register of Historic Places in 2000.

See also
National Register of Historic Places listings in Plymouth County, Massachusetts
National Register of Historic Places listings in Norfolk County, Massachusetts

References

National Register of Historic Places in Plymouth County, Massachusetts
National Register of Historic Places in Norfolk County, Massachusetts
Parks in Plymouth County, Massachusetts
Parks in Norfolk County, Massachusetts
Sports in Brockton, Massachusetts
Golf clubs and courses in Massachusetts

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2,4,6-Tris(trinitromethyl)-1,3,5-triazine is a chemical compound that is a derivative of triazine first prepared in 1995. It is synthesized by destructive nitration of 2,4,6-tricarboxyl-1,3,5-triazine. It is noteworthy for having more nitro groups than it does carbon atoms, thus potentially being useful as an oxygen source, or added to oxygen-poor explosives to increase their power.

Derivatives have been prepared by nucleophilic displacement of the nitro groups with azide and hydrazine.

References

Triazines
Nitro compounds
Explosive chemicals


A Fresnel lens ( ;  ; or  ) is a type of composite compact lens which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections.

The simpler dioptric (purely refractive) form of the lens was first proposed by Georges-Louis Leclerc, Comte de Buffon, and independently reinvented by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses. The catadioptric form of the lens, entirely invented by Fresnel, has outer prismatic elements that use total internal reflection as well as refraction to capture more oblique light from the light source and add it to the beam, making it more visible at greater distances.

The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet.

Because of its use in lighthouses, it has been called "the invention that saved a million ships".

History

Forerunners

The first person to focus a lighthouse beam using a lens was apparently the London glass-cutter Thomas Rogers, who proposed the idea to Trinity House in 1788. The first Rogers lenses, 53cm in diameter and 14cm thick at the center, were installed at the Old Lower Lighthouse at Portland Bill in 1789. Behind each lamp was a back-coated spherical glass mirror, which reflected rear radiation back through the lamp and into the lens. Further samples were installed at Howth Baily, North Foreland, and at least four other locations by 1804. But much of the light was wasted by absorption in the glass.

In 1748, Georges-Louis Leclerc, Comte de Buffon was the first to replace a convex lens with a series of concentric annular prisms, ground as steps in a single piece of glass,to reduce weight and absorption. In 1790 (although secondary sources give the date as 1773 or 1788), the Marquis de Condorcet suggested that it would be easier to make the annular sections separately and assemble them on a frame; but even that was impractical at the time. These designs were intended not for lighthouses, but for burning glasses. David Brewster, however, proposed a system similar to Condorcet's in 1811, and by 1820 was advocating its use in British lighthouses.

Publication and refinement

The French  (Commission of Lighthouses) was established by Napoleon in 1811, and placed under the authority of French physicist Augustin-Jean Fresnel's employer, the Corps of Bridges and Roads. As the members of the commission were otherwise occupied, it achieved little in its early years. However, on 21 June 1819—three months after winning the physics  of the Academy of Sciences for his celebrated memoir on diffraction—Fresnel was "temporarily" seconded to the commission on the recommendation of François Arago (a member since 1813), to review possible improvements in lighthouse illumination.

By the end of August 1819, unaware of the Buffon-Condorcet-Brewster proposal, Fresnel made his first presentation to the commission, recommending what he called  ('lenses by steps') to replace the reflectors then in use, which reflected only about half of the incident light. Another report by Fresnel, dated 29 August 1819 (Fresnel, 1866–70, vol. 3, pp. 15–21), concerns tests on reflectors, and does not mention stepped lenses except in an unrelated sketch on the last page of the manuscript. The minutes of the meetings of the Commission go back only to 1824, when Fresnel himself took over as Secretary. Thus it the exact date on which Fresnel formally recommended  is unknown. Much to Fresnel's embarrassment, one of the assembled commissioners, Jacques Charles, recalled Buffon's suggestion. However, whereas Buffon's version was biconvex and in one piece, Fresnel's was plano-convex and made of multiple prisms for easier construction.

With an official budget of 500 francs, Fresnel approached three manufacturers. The third, François Soleil, found a way to remove defects by reheating and remolding the glass. Arago assisted Fresnel with the design of a modified Argand lamp with concentric wicks (a concept that Fresnel attributed to Count Rumford), and accidentally discovered that fish glue was heat-resistant, making it suitable for use in the lens. The prototype, finished in March 1820, had a square lens panel 55cm on a side, containing 97 polygonal (not annular) prisms—and so impressed the Commission that Fresnel was asked for a full eight-panel version. This model, completed a year later in spite of insufficient funding, had panels 76cm square. In a public spectacle on the evening of 13 April 1821, it was demonstrated by comparison with the most recent reflectors, which it suddenly rendered obsolete.

Soon after this demonstration, Fresnel published the idea that light, including apparently unpolarized light, consists exclusively of transverse waves, and went on to consider the implications for double refraction and partial reflection.

Fresnel acknowledged the British lenses and Buffon's invention in a memoir read on 29 July 1822 and printed in the same year. The date of that memoir may be the source of the claim that Fresnel's lighthouse advocacy began two years later than Brewster's; but the text makes it clear that Fresnel's involvement began no later than 1819.

Fresnel's next lens was a rotating apparatus with eight "bull's-eye" panels, made in annular arcs by Saint-Gobain, giving eight rotating beams—to be seen by mariners as a periodic flash. Above and behind each main panel was a smaller, sloping bull's-eye panel of trapezoidal outline with trapezoidal elements. This refracted the light to a sloping plane mirror, which then reflected it horizontally, 7 degrees ahead of the main beam, increasing the duration of the flash. Below the main panels were 128 small mirrors arranged in four rings, stacked like the slats of a louver or Venetian blind. Each ring, shaped like a frustum of a cone, reflected the light to the horizon, giving a fainter steady light between the flashes. The official test, conducted on the unfinished  on 20 August 1822, was witnessed by the Commission—and by Louis XVIII and his entourage—from  away. The apparatus was stored at Bordeaux for the winter, and then reassembled at Cordouan Lighthouse under Fresnel's supervision—in part by Fresnel's own hands. On 25 July 1823, the world's first lighthouse Fresnel lens was lit. As expected, the light was visible to the horizon, more than  out.

The day before the test of the Cordouan lens in Paris, a committee of the Academy of Sciences reported on Fresnel's memoir and supplements on double refraction—which, although less well known to modern readers than his earlier work on diffraction, struck a more decisive blow for the wave theory of light. Between the test and the reassembly at Cordouan, Fresnel submitted his papers on photoelasticity (16 September 1822), elliptical and circular polarization and optical rotation (9 December), and partial reflection and total internal reflection (7 January 1823), essentially completing his reconstruction of physical optics on the transverse wave hypothesis. Shortly after the Cordouan lens was lit, Fresnel started coughing up blood.

In May 1824, Fresnel was promoted to Secretary of the , becoming the first member of that body to draw a salary, albeit in the concurrent role of Engineer-in-Chief. Late that year, being increasingly ill, he curtailed his fundamental research and resigned his seasonal job as an examiner at the , in order to save his remaining time and energy for his lighthouse work.

In the same year he designed the first fixed lens—for spreading light evenly around the horizon while minimizing waste above or below. Ideally the curved refracting surfaces would be segments of toroids about a common vertical axis, so that the dioptric panel would look like a cylindrical drum. If this was supplemented by reflecting (catoptric) rings above and below the refracting (dioptric) parts, the entire apparatus would look like a beehive. The second Fresnel lens to enter service was indeed a fixed lens, of third order, installed at Dunkirk by 1 February 1825. However, due to the difficulty of fabricating large toroidal prisms, this apparatus had a 16-sided polygonal plan.

In 1825 Fresnel extended his fixed-lens design by adding a rotating array outside the fixed array. Each panel of the rotating array was to refract part of the fixed light from a horizontal fan into a narrow beam.

Also in 1825, Fresnel unveiled the  ('lighthouse map'), calling for a system of 51 lighthouses plus smaller harbor lights, in a hierarchy of lens sizes called "orders" (the first being the largest), with different characteristics to facilitate recognition: a constant light (from a fixed lens), one flash per minute (from a rotating lens with eight panels), and two per minute (16 panels).

In late 1825, to reduce the loss of light in the reflecting elements, Fresnel proposed to replace each mirror with a catadioptric prism, through which the light would travel by refraction through the first surface, then total internal reflection off the second surface, then refraction through the third surface. The result was the lighthouse lens as we now know it. In 1826 he assembled a small model for use on the , but he did not live to see a full-sized version: he died on 14 July 1827, at the age of 39.

After Fresnel

The first stage of the development of lighthouse lenses after the death of Augustin Fresnel consisted in the implementation of his designs. This was driven in part by his younger brother Léonor—who, like Augustin, was trained as a civil engineer but, unlike Augustin, had a strong aptitude for management. Léonor entered the service of the Lighthouse Commission in 1825, and went on to succeed Augustin as Secretary.

The first fixed lens to be constructed with toroidal prisms was a first-order apparatus designed by the Scottish engineer Alan Stevenson under the guidance of Léonor Fresnel, and fabricated by Isaac Cookson & Co. using French glass; it entered service at the Isle of May, Scotland, on 22 September 1836. The first large catadioptric lenses were made in 1842 for the lighthouses at Gravelines and Île Vierge, France; these were fixed third-order lenses whose catadioptric rings (made in segments) were one metre in diameter. Stevenson's first-order Skerryvore lens, lit in 1844, was only partly catadioptric; it was similar to the Cordouan lens except that the lower slats were replaced by French-made catadioptric prisms, while mirrors were retained at the top. The first fully catadioptric first-order lens, installed at Pointe d'Ailly in 1852, also gave eight rotating beams plus a fixed light at the bottom; but its top section had eight catadioptric panels focusing the light about 4 degrees ahead of the main beams, in order to lengthen the flashes. The first fully catadioptric lens with purely revolving beams—also of first order—was installed at Saint-Clément-des-Baleines in 1854, and marked the completion of Augustin Fresnel's original Carte des Phares.

Thomas Stevenson (younger brother of Alan) went a step beyond Fresnel with his "holophotal" lens, which focused the light radiated by the lamp in nearly all directions, forward or backward, into a single beam. The first version, described in 1849, consisted of a standard Fresnel bull's-eye lens, a paraboloidal reflector, and a rear hemispherical reflector (functionally equivalent to the Rogers mirror of 60 years earlier, except that it subtended a whole hemisphere). Light radiated into the forward hemisphere but missing the bull's-eye lens was deflected by the paraboloid into a parallel beam surrounding the bull's-eye lens, while light radiated into the backward hemisphere was reflected back through the lamp by the spherical reflector (as in Rogers' arrangement), to be collected by the forward components. The first unit was installed at North Harbour, Peterhead, in August 1849. Stevenson called this version a "catadioptric holophote", although each of its elements was either purely reflective or purely refractive. In the second version of the holophote concept, the bull's-eye lens and paraboloidal reflector were replaced by a catadioptric Fresnel lens—as conceived by Fresnel, but expanded to cover the whole forward hemisphere. The third version, which Stevenson confusingly called a "dioptric holophote", was more innovative: it retained the catadioptric Fresnel lens for the front hemisphere, but replaced the rear hemispherical reflector with a hemispherical array of annular prisms, each of which used two total internal reflections to turn light diverging from the center of the hemisphere back toward the center. The result was an all-glass holophote, with no losses from metallic reflections.

James Timmins Chance modified Thomas Stevenson's all-glass holophotal design by arranging the double-reflecting prisms about a vertical axis. The prototype was shown at the 1862 International Exhibition in London. Later, to ease manufacturing, Chance divided the prisms into segments, and arranged them in a cylindrical form while retaining the property of reflecting light from a single point back to that point. Reflectors of this form, paradoxically called "dioptric mirrors", proved particularly useful for returning light from the landward side of the lamp to the seaward side.

As lighthouses proliferated, they became harder to distinguish from each other, leading to the use of colored filters, which wasted light. In 1884, John Hopkinson eliminated the need for filters by inventing the "group-flashing" lens, in which the dioptric and/or the catadioptric panels were split so as to give multiple flashes—allowing lighthouses to be identified not only by frequency of flashes, but also by multiplicity of flashes. Double-flashing lenses were installed at Tampico (Mexico) and Little Basses (Sri Lanka) in 1875, and a triple-flashing lens at Casquets Lighthouse (Channel Islands) in 1876. The example shown (right) is the double-flashing lens of the Point Arena Light, which was in service from 1908 to 1977.

The development of hyper-radial lenses was driven in part by the need for larger light sources, such as gas lights with multiple jets, which required a longer focal length for a given beam-width, hence a larger lens to collect a given fraction of the generated light. The first hyper-radial lens was built for the Stevensons in 1885 by F. Barbier & Cie of France, and tested at South Foreland Lighthouse with various light sources. Chance Brothers (Hopkinson's employers) then began constructing hyper-radials, installing their first at Bishop Rock Lighthouse in 1887. In the same year, Barbier installed a hyper-radial at Tory Island. But only about 30 hyper-radials went into service before the development of more compact bright lamps rendered such large optics unnecessary (see Hyperradiant Fresnel lens).

Production of one-piece stepped dioptric lenses—roughly as envisaged by Buffon—became feasible in 1852, when John L. Gilliland of the Brooklyn Flint-Glass Company patented a method of making lenses from pressed and molded glass. The company made small bull's-eye lenses for use on railroads, steamboats, and docks; such lenses were common in the United States by the 1870s. In 1858 the company produced "a very small number of pressed flint-glass sixth-order lenses" for use in lighthouses—the first Fresnel lighthouse lenses made in America. By the 1950s, the substitution of plastic for glass made it economic to use Fresnel lenses as condensers in overhead projectors.

Design

The Fresnel lens reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections. An ideal Fresnel lens would have an infinite number of sections. In each section, the overall thickness is decreased compared to an equivalent simple lens. This effectively divides the continuous surface of a standard lens into a set of surfaces of the same curvature, with stepwise discontinuities between them.

In some lenses, the curved surfaces are replaced with flat surfaces, with a different angle in each section. Such a lens can be regarded as an array of prisms arranged in a circular fashion with steeper prisms on the edges and a flat or slightly convex center. In the first (and largest) Fresnel lenses, each section was actually a separate prism. 'Single-piece' Fresnel lenses were later produced, being used for automobile headlamps, brake, parking, and turn signal lenses, and so on. In modern times, computer-controlled milling equipment (CNC) or 3-D printers might be used to manufacture more complex lenses.

Fresnel lens design allows a substantial reduction in thickness (and thus mass and volume of material) at the expense of reducing the imaging quality of the lens, which is why precise imaging applications such as photography usually still use larger conventional lenses.

Fresnel lenses are usually made of glass or plastic; their size varies from large (old historical lighthouses, meter size) to medium (book-reading aids, OHP viewgraph projectors) to small (TLR/SLR camera screens, micro-optics). In many cases they are very thin and flat, almost flexible, with thicknesses in the  range.

Most modern Fresnel lenses consist only of refractive elements. Lighthouse lenses, however, tend to include both refracting and reflecting elements, the latter being outside the metal rings seen in the photographs. While the inner elements are sections of refractive lenses, the outer elements are reflecting prisms, each of which performs two refractions and one total internal reflection, avoiding the light loss that occurs in reflection from a silvered mirror.

Lighthouse lens sizes

Fresnel designed six sizes of lighthouse lenses, divided into four orders based on their size and focal length.  The 3rd and 4th orders were sub-divided into "large" and "small". In modern use, the orders are classified as first through sixth order. An intermediate size between third and fourth order was added later, as well as sizes above first order and below sixth.

A first-order lens has a focal length of  and stands about  high, and  wide. The smallest (sixth) order has a focal length of  and a height of .

The largest Fresnel lenses are called hyperradiant (or hyper-radial). One such lens was on hand when it was decided to build and outfit the Makapuu Point Light in Hawaii. Rather than order a new lens, the huge optic construction,  tall and with over a thousand prisms, was used there.

Types

There are two main types of Fresnel lens: imaging and non-imaging. Imaging Fresnel lenses use segments with curved cross-sections and produce sharp images, while non-imaging lenses have segments with flat cross-sections, and do not produce sharp images. As the number of segments increases, the two types of lens become more similar to each other. In the abstract case of an infinite number of segments, the difference between curved and flat segments disappears.

Imaging lenses can be classified as:

 Spherical A spherical Fresnel lens is equivalent to a simple spherical lens, using ring-shaped segments that are each a portion of a sphere, that all focus light on a single point. This type of lens produces a sharp image, although not quite as clear as the equivalent simple spherical lens due to diffraction at the edges of the ridges.
 Cylindrical A cylindrical Fresnel lens is equivalent to a simple cylindrical lens, using straight segments with circular cross-section, focusing light on a single line. This type produces a sharp image, although not quite as clear as the equivalent simple cylindrical lens due to diffraction at the edges of the ridges.

Non-imaging lenses can be classified as:

 Spot A non-imaging spot Fresnel lens uses ring-shaped segments with cross sections that are straight lines rather than circular arcs. Such a lens can focus light on a small spot, but does not produce a sharp image. These lenses have application in solar power, such as focusing sunlight on a solar panel. Fresnel lenses may be used as components of Köhler illumination optics resulting in very effective nonimaging optics Fresnel-Köhler (FK) solar concentrators.
 Linear A non-imaging linear Fresnel lens uses straight segments whose cross sections are straight lines rather than arcs. These lenses focus light into a narrow band. They do not produce a sharp image, but can be used in solar power, such as for focusing sunlight on a pipe, to heat the water within.

Uses

Illumination

High-quality glass Fresnel lenses were used in lighthouses, where they were considered state of the art in the late 19th and through the middle of the 20th centuries; most lighthouses have now retired glass Fresnel lenses from service and replaced them with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses. Lighthouse Fresnel lens systems typically include extra annular prismatic elements, arrayed in faceted domes above and below the central planar Fresnel, in order to catch all light emitted from the light source. The light path through these elements can include an internal reflection, rather than the simple refraction in the planar Fresnel element. These lenses conferred many practical benefits upon the designers, builders, and users of lighthouses and their illumination. Among other things, smaller lenses could fit into more compact spaces. Greater light transmission over longer distances, and varied patterns, made it possible to triangulate a position.

Perhaps the most widespread use of Fresnel lenses, for a time, occurred in automobile headlamps, where they can shape the roughly parallel beam from the parabolic reflector to meet requirements for dipped and main-beam patterns, often both in the same headlamp unit (such as the European H4 design). For reasons of economy, weight, and impact resistance, newer cars have dispensed with glass Fresnel lenses, using multifaceted reflectors with plain polycarbonate lenses. However, Fresnel lenses continue in wide use in automobile tail, marker, and reversing lights.

Glass Fresnel lenses also are used in lighting instruments for theatre and motion pictures (see Fresnel lantern); such instruments are often called simply Fresnels. The entire instrument consists of a metal housing, a reflector, a lamp assembly, and a Fresnel lens. Many Fresnel instruments allow the lamp to be moved relative to the lens' focal point, to increase or decrease the size of the light beam. As a result, they are very flexible, and can often produce a beam as narrow as 7° or as wide as 70°. The Fresnel lens produces a very soft-edged beam, so is often used as a wash light. A holder in front of the lens can hold a colored plastic film (gel) to tint the light or wire screens or frosted plastic to diffuse it. The Fresnel lens is useful in the making of motion pictures not only because of its ability to focus the beam brighter than a typical lens, but also because the light is a relatively consistent intensity across the entire width of the beam of light.

Aircraft carriers and naval air stations typically use Fresnel lenses in their optical landing systems. The "meatball" light aids the pilot in maintaining proper glide slope for the landing. In the center are amber and red lights composed of Fresnel lenses. Although the lights are always on, the angle of the lens from the pilot's point of view determines the color and position of the visible light. If the lights appear above the green horizontal bar, the pilot is too high. If it is below, the pilot is too low, and if the lights are red, the pilot is very low.

Fresnel lenses are also commonly used in searchlights, spotlights, and flashlights.

Imaging

Fresnel lenses are used as simple hand-held magnifiers. They are also used to correct several visual disorders, including ocular-motility disorders such as strabismus. Fresnel lenses have been used to increase the visual size of CRT displays in pocket televisions, notably the Sinclair TV80. They are also used in traffic lights.

Fresnel lenses are used in left-hand-drive European lorries entering the UK and Republic of Ireland (and vice versa, right-hand-drive Irish and British trucks entering mainland Europe) to overcome the blind spots caused by the driver operating the lorry while sitting on the wrong side of the cab relative to the side of the road the car is on. They attach to the passenger-side window.

Another automobile application of a Fresnel lens is a rear view enhancer, as the wide view angle of a lens attached to the rear window permits examining the scene behind a vehicle, particularly a tall or bluff-tailed one, more effectively than a rear-view mirror alone.

Fresnel lenses have also been used in the field of popular entertainment. The British rock artist Peter Gabriel made use of them in his early solo live performances to magnify the size of his head, in contrast to the rest of his body, for dramatic and comic effect. In the Terry Gilliam film Brazil, plastic Fresnel screens appear ostensibly as magnifiers for the small CRT monitors used throughout the offices of the Ministry of Information. However, they occasionally appear between the actors and the camera, distorting the scale and composition of the scene to humorous effect. The Pixar movie Wall-E features a Fresnel lens in the scenes where the protagonist watches the musical Hello, Dolly! magnified on an iPod.

Virtual reality headsets, such as the Meta Quest 2 and the HTC Vive Pro use Fresnel lenses, as they allow a thinner and lighter form factor than regular lenses. Newer devices, such as the Meta Quest Pro, have switched to a pancake lens design due to its smaller form factor and less chromatic aberration than Fresnel lenses.

Multi-focal Fresnel lenses are also used as a part of retina identification cameras, where they provide multiple in- and out-of-focus images of a fixation target inside the camera. For virtually all users, at least one of the images will be in focus, thus allowing correct eye alignment.

Canon and Nikon have used Fresnel lenses to reduce the size of telephoto lenses. Photographic lenses that include Fresnel elements can be much shorter than corresponding conventional lens design. Nikon calls the technology Phase Fresnel. The Polaroid SX-70 camera used a Fresnel reflector as part of its viewing system. View and large format cameras can utilize a Fresnel lens in conjunction with the ground glass, to increase the perceived brightness of the image projected by a lens onto the ground glass, thus aiding in adjusting focus and composition.

Projection

The use of Fresnel lenses for image projection reduces image quality, so they tend to occur only where quality is not critical or where the bulk of a solid lens would be prohibitive. Cheap Fresnel lenses can be stamped or molded of transparent plastic and are used in overhead projectors and projection televisions.

Fresnel lenses of different focal lengths (one collimator, and one collector) are used in commercial and DIY projection. The collimator lens has the lower focal length and is placed closer to the light source, and the collector lens, which focuses the light into the triplet lens, is placed after the projection image (an active matrix LCD panel in LCD projectors). Fresnel lenses are also used as collimators in overhead projectors.

Solar power

Since plastic Fresnel lenses can be made larger than glass lenses, as well as being much cheaper and lighter, they are used to concentrate sunlight for heating in solar cookers, in solar forges, and in solar collectors used to heat water for domestic use. They can also be used to generate steam or to power a Stirling engine.

Fresnel lenses can concentrate sunlight onto solar cells with a ratio of almost 500:1. This allows the active solar-cell surface to be reduced, lowering cost and allowing the use of more efficient cells that would otherwise be too expensive. In the early 21st century, Fresnel reflectors began to be used in concentrating solar power (CSP) plants to concentrate solar energy. One application was to preheat water at the coal-fired Liddell Power Station, in Hunter Valley Australia.

Fresnel lenses can be used to sinter sand, allowing 3D printing in glass.

See also

 Fresnel imager
 Fresnel zone plate
 Lenticular lens
 Linear Fresnel reflector
 Prism lighting

References

Bibliography

 M. Born and E. Wolf, Principles of Optics, 7th Ed., Cambridge, 1999.
 G.-A. Boutry, 1948, "Augustin Fresnel: His time, life and work, 1788–1827", Science Progress, vol. 36, no. 144 (October 1948), pp. 587–604; jstor.org/stable/43413515.
 J. Z. Buchwald, 1989, The Rise of the Wave Theory of Light: Optical Theory and Experiment in the Early Nineteenth Century, University of Chicago Press, .
 J. Elton, 2009, "A Light to Lighten our Darkness: Lighthouse Optics and the Later Development of Fresnel's Revolutionary Refracting Lens 1780–1900", International Journal for the History of Engineering & Technology, vol. 79, no. 2 (July 2009), pp. 183–244; .
 A. Fresnel, 1822, "Mémoire sur un nouveau système d'éclairage des phares", read 29 July 1822; reprinted in Fresnel, 1866–1870, vol. 3, pp. 97–126; translated by T. Tag as "Memoir upon a new system of lighthouse illumination", U.S. Lighthouse Society, accessed 26 August 2017; archived 19 August 2016. (Cited page numbers refer to the translation.)
 A. Fresnel (ed. H. de Sénarmont, E. Verdet, and L. Fresnel), 1866–1870, Oeuvres complètes d'Augustin Fresnel (3 vols.), Paris: Imprimerie Impériale; vol. 1 (1866), vol. 2 (1868), vol. 3 (1870).
 T. H. Levitt, 2013, A Short Bright Flash: Augustin Fresnel and the Birth of the Modern Lighthouse, New York: W.W. Norton, .
 T. Young (ed. G. Peacock), 1855, Miscellaneous Works of the late Thomas Young, London: J. Murray, vol. 1.

Further reading

 "The Fresnel Lens", The Keeper's Log, Winter 1985, pp. 12–14.
 U.S. Coast Guard, Aids to Navigation, Washington, DC: U.S. Government Printing Office, 1945.
 U.S. Coast Guard, Lighthouses, Lenses, Illuminants, Engineering, & Augustin Fresnel: A Historical Bibliography on Works Published Through 2007.

External links

 United States Lighthouse Society, especially "Fresnel Lenses ".
 W. A. Britten, "The Fresnel lens" (with photographs).
 J. Francis, "Fresnel Lens - Maxwell Simulation", 13 April 2009.
 J. Hare, "How the Fresnel lens works" (5-minute video), Vega Science Trust, 2008.
 .
 The Fresnel Lens: the Invention That Saved 1000 Ships

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