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University of Toronto Faculty of Medicine

The Temerty Faculty of Medicine (previously Faculty of Medicine) is the medical school of the University of Toronto. Founded in 1843, the faculty is based in Downtown Toronto and is one of Canada's oldest institutions of medical studies, being known for the discovery of insulin, stem cells and the site of the first single and double lung transplants in the world.

History
The university originally opened its medical school in 1843, providing instruction in medicine and medical sciences. In 1853, it suspended the school's teaching program and transferred teaching duties to the city's three proprietary schools: Trinity Medical College, the Toronto School of Medicine and Woman's Medical College. Because proprietary schools could not grant degrees, the university's medical school retained the responsibility of holding examinations and conferring medical degrees. As the university kept raising its standards, the medical examinations became increasingly rigorous and scientific. This led to fewer medical students from proprietary schools deciding to obtain university degrees, which were not required for medical practice at the time. In 1887, the university resumed medical teaching in its Faculty of Medicine. The faculty promptly absorbed the Toronto School of Medicine, which could no longer compete with the university as it faced heavy costs of scientific work and higher examination standards set by the faculty. The 1910 Flexner Report on the state of medical education in the United States and Canada, which led to the closures of many medical schools across the continent, nonetheless singled out a select few medical schools for praise, among them Toronto's Faculty of Medicine. Flexner praised the "high quality of instruction" offered at Toronto and noted that its equipment "among the best on the continent".

The Faculty, in partnership with the University of Toronto Mississauga and Trillium Health Partners opened the Mississauga Academy of Medicine in August 2011 with 54 first-year students. As of 2014, the academy has a total of 216 students enrolled in the four-year program. The new facility is located across two floors inside the new Terrence Donnelly Health Sciences Complex and provides brand new classrooms, seminar rooms, computer facilities, learning spaces and laboratories. Students are provided with fully equipped student lounge and outdoor terrace to relax and socialize. Students are able to share lectures and learning experiences both inside and outside the classroom through advanced technologies.

In 2022, the Ontario government announced that University of Toronto Scarborough would provide medical training as well. The campus will receive 30 undergraduate seats and 45 postgraduate positions.

Curriculum
In 2016, the Faculty of Medicine implemented the new Foundations Curriculum, moving away from the traditional lecture based style of teaching based on anatomy, physiology, pathology and pharmacology and into a case-based learning approach with early clinical exposure.

The Doctor of Medicine program at the University of Toronto is a 4-year MD program with a total enrollment of about 850 students. The first two years are known as the preclerkship curriculum, during which M.D. candidates acquire the basic biomedical and human anatomy knowledge. The principles of medical ethics, professionalism and medical jurisprudence are also taught in preclerkship. The final two years form the clerkship curriculum that takes place in hospitals and ambulatory clinics. The core clerkship rotations cover the essential medical specialties: surgery and internal medicine, psychiatry, pediatrics, obstetrics and gynecology, family medicine, ambulatory experience, neurology, emergency medicine, anesthesia, ophthalmology, otolaryngology and dermatology. Additional rotations are devoted to elective clerkships that provide training in subdisciplines within the major specialities.

In 2018, the average accepted undergraduate weighted GPA was 3.96 (on the University of Toronto Weighted GPA (wGPA) Formula) and the median score in the numerically graded sections of the MCAT was 11. The University of Toronto is one of only a few programs in Canada to accept international students through its admission process. The faculty also offers the MD/PhD degree jointly with University of Toronto doctoral programs, in addition to other degrees of Master of Science, master of public health, master of health science, doctor of philosophy, and post-doctoral fellowships.

Departments, hospitals and research
The Faculty of Medicine is subdivided into 26 separate departments: Anesthesiology and Pain Medicine, Biochemistry, Biomedical Engineering, Institute of Donnelly Centre for Cellular and Biomolecular Research, Family and Community Medicine, Immunology, Laboratory Medicine and Pathobiology, Medical Biophysics, Medical Imaging, the Institute of Medical Science, Medicine, Molecular Genetics, Nutritional Sciences, Obstetrics and Gynaecology, Occupational Science and Occupational Therapy, Ophthalmology and Vision Sciences, Otolaryngology Head and Neck Surgery, Paediatrics, Pharmacology and Toxicology, Physical Therapy, Physiology, Psychiatry, Radiation Oncology, Rehabilitation Sciences Institute, Speech-Language Pathology and Surgery.

The Faculty of Medicine is also the only medical school in the Greater Toronto Area and operates a health network that comprises twelve teaching hospitals with significant emphasis on tertiary care, including medical treatment, research and advisory services to patients and clients from Canada and abroad. The Faculty houses Biosafety level 3 facilities.

The faculty is associated with two level 1 adult trauma centres, a multi-organ transplant hospital, a pediatric hospital, a psychiatric hospital, a geriatric hospital, four rehabilitation institutes and several general hospitals.

The teaching hospitals are arranged in four hospital networks, which are the University Health Network, Unity Health Toronto, the Sinai Health System, the Trillium Health Partners, as well as three major teaching hospitals outside of the system, Sunnybrook Health Sciences Centre, Women's College Hospital and The Hospital for Sick Children.

 * The University Health Network consists of three specialized hospitals: Toronto General Hospital for cardiology and organ transplants; Princess Margaret Cancer Centre for oncology as the home of the Ontario Cancer Institute; and Toronto Western Hospital for neuroscience and musculoskeletal health.
 * Unity Health Toronto consists of St Michael's Hospital, an adult hospital and trauma center, Providence Healthcare, a rehabilitation institute and St. Joseph's Health Centre, a community teaching hospital.
 * Sinai Health System consists of Mount Sinai Hospital, a general hospital and Bridgepoint Active Healthcare, a rehabilitation institute.
 * Trillium Health Partners consists of Mississauga Hospital, a general hospital, Credit Valley Hospital, community teaching hospital,
 * Sunnybrook Health Sciences Centre is an adult hospital with regional cancer and trauma centres.
 * Women's College Hospital is an ambulatory hospital focused on women's health.
 * The Hospital for Sick Children is the pediatric medical centre specializing in treatments for childhood diseases and injuries.

Rotations may also involve community teaching hospitals, which include North York General Hospital, St. Joseph's Health Centre, Michael Garron Hospital, Scarborough General Hospital, Credit Valley Hospital and Markham Stouffville Hospital.

Collaborations with industry
MaRS Discovery District is an affiliated corporation that was established to help commercialize the faculty's life science and medical research through partnerships with private enterprises.

On April 7, 2022, the University of Toronto announced a partnership with American biotechnology company Moderna intended to develop new tools to prevent and treat infectious diseases, collaborating with researchers in the fields of molecular genetics, biomedical engineering, and biochemistry. The collaboration is a joint venture across U of T's Faculties of Applied Science and Engineering and Medicine.

Reputation
In 2023 the school was ranked 4th in the world for clinical medicine and surgery by U.S. News & World Report. It was also ranked 5th in the world for pre-clinical, clinical and health by The Times Higher Education in its 2022 listings. It was ranked 13th in the world for medicine by the QS World Ranking. In 2020 the school was ranked 15th in the world Academic Ranking of World Universities for clinical medicine.

While not exclusively regarding the Temerty Faculty of Medicine, in 2023, NATURE ranked the University of Toronto 3rd in the world for Health sciences

Notable alumni

 * Jennie Smillie Robertson, class of 1909: First female surgeon in Canada
 * Maud Menten, class of 1911: developed the mathematics of enzyme kinetics with Leonor Michaelis
 * Theodore Drake, class of 1914: pediatrician and inventor of the baby food Pablum
 * Norman Bethune, class of 1916: physician, humanitarian and medical innovator
 * Frederick Banting, class of 1916, and Charles Best, class of 1925: Co-discoverers of insulin with professor of physiology John Macleod
 * Gladys Boyd, class of 1918: pediatrician, pioneer in treatment of juvenile diabetes
 * Victoria Chung, class of 1922: medical missionary and first Canadian of Chinese descent to graduate from medical school in Canada
 * Jessie Gray, class of 1934, and professor of clinical surgery: Canada's "First Lady of Surgery", lecturer, and researcher
 * Wilfred Gordon Bigelow, class of 1938: Developed the artificial pacemaker and the use of hypothermia in open heart surgery
 * Tom Pashby, class of 1940: ophthalmologist and sport safety advocate, Order of Canada, Canada's Sport Hall of Fame
 * Gordon Bell, class of 1943: pioneered treatment of alcohol addiction in Canada and invented the alco-dial, a device to estimate blood alcohol levels.
 * Henry J. M. Barnett, class of 1944: pioneered use of aspirin as a preventive therapy for heart attack and stroke
 * Robert B. Salter, class of 1947: developed the continuous passive motion (CPM) treatment to aid recovery of joints after trauma
 * William Thornton Mustard, class of 1947: pediatric cardiac surgeon, developer of the Mustard procedure
 * Ernest McCulloch, class of 1948: cellular biologist and Lasker Award recipient credited with the discovery of the stem cell
 * Shaf Keshavjee, class of 1985: transplant surgeon and ex-vivo lung transplant pioneer
 * C. Miller Fisher, class of 1938: described lacunar strokes and identified transient ischemic attacks as stroke precursors.
 * Daniel J. Drucker OC, FRS, class of 1980: University Professor of medicine, research endocrinologist; his discoveries regarding the GLP family of hormones revolutionized treatment of diabetes

Notable past or present faculty

 * John E. Dick, professor of molecular genetics: Identified the cancer stem cell
 * Brenda Andrews, professor at the Donnelly Centre for Cellular and Biomolecular Research and researcher
 * Anthony Pawson, professor of molecular and medical genetics, 1985–2013: Researcher in signal transduction
 * Tirone E. David, professor of surgery, Developed valve-sparing aortic root replacement
 * Lap-Chee Tsui, professor of genetics, 1983–2002: Former vice-chancellor of the University of Hong Kong and president of Human Genome Organisation
 * Stephen Scherer, University Professor in the Department of Molecular Genetics. Scherer's discoveries led to the initial description of genome-wide copy number variations (CNVs). He founded Canada's first human genome centre, the Centre for Applied Genomics (TCAG) at the Hospital for Sick Children.
 * Tak Wah Mak, professor of medical biophysics, 1975–: Discovered the T-cell receptor
 * James Till, professor of medical biophysics, 1958–97: Academic on Internet research ethics
 * William Boyd, professor of pathology, 1937–1951, Author of important pathology textbooks
 * John C. Boileau Grant, professor of anatomy, 1930–56, Author of notable anatomy textbooks
 * Dafna D. Gladman, professor of medicine and Senior Scientist, Krembil Research Institute, noted for research on psoriatic arthritis, systemic lupus erythematosus,  and rheumatoid arthritis
 * Vivek Rao, cardiac surgeon and medical researcher, Munk Chair in Advanced Cardiac Therapeutics at the Peter Munk Cardiac Centre, Toronto General Hospital, and Senior Scientist in the Division of Experimental Therapeutics at the Toronto General Research Institute


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User talk:Franc28

Proposed deletion of Transcendental argument for the non-existence of God

The article Transcendental argument for the non-existence of God has been proposed for deletion  because of the following concern:
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While all contributions to Wikipedia are appreciated, content or articles may be deleted for any of several reasons.

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Please consider improving the article to address the issues raised. Removing  will stop the proposed deletion process, but other deletion processes exist. The speedy deletion process can result in deletion without discussion, and articles for deletion allows discussion to reach consensus for deletion. NBeale (talk) 07:20, 20 February 2010 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: User talk:Franc28


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User:Pilonieta~enwiki

LOS nuemros son distintos cuando se ven en armonia

title: User:Pilonieta~enwiki


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Category:Marxism

Marxism is a method of socioeconomic analysis that analyzes class relations and societal conflict using a materialist interpretation of historical development and a dialectical view of social transformation. It originates from the mid-to-late-19th-century works of German philosophers Karl Marx and Friedrich Engels.

title: Category:Marxism


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Climbing specialist

A climbing specialist or climber, also known as a grimpeur, is a road bicycle racer who can ride especially well on highly inclined roads, such as those found among hills or mountains.

Role of climber in a race
In a sustained climb, the average speed declines, the aerodynamic advantage of drafting is diminished and the setting of the group pace becomes more important. A good climber modulates his speed and chooses the best line on a climb, allowing the following riders to have an easier job. If the group maintains a high tempo, it is more difficult for a rider to attack and ride away from the group.

Another important role in climbing is that of attacker or counter-attacker. Climbing specialists use their superior abilities either to attack on climbs and thereby gap the competitors, knowing that only other climbing specialists will be able to stay with them, or simply to maintain a high pace that others cannot match. A successful escape can help the climber achieve a victory if the race has a mountain-top finish, or even in a flat finish if the climber is able to maintain his lead after the climb is over. Climbing stages, along with individual time trials, are key stages in winning long stage races.

In recent years, climbing specialists have been deployed as Super-domestiques, protecting team leaders with All-round capabilities by setting a strong tempo in mountain stages to deter attacks from rivals, a tactic known as a 'train'. Examples of this include Team Sky climbers Wout Poels, Mikel Landa and Mikel Nieve helping Chris Froome in his multiple Grand Tour victories. Froome himself played a similar role in service of Bradley Wiggins at the 2012 Tour de France.

Types of climbers
Climbers tend to have a lot of endurance and specifically developed muscles for long hard climbs. They also tend to have a slim, lightweight physique, but some can become good climbers through concerted training.

The most successful climbing specialists come in different shapes and specializations. Climbers with very small physique such as José Rujano (48 kg), Nairo Quintana (58 kg), Roberto Heras  (60 kg), Alberto Contador  (61 kg) and Gilberto Simoni (58 kg) thrive when the climbs reach dizzying heights and incredibly steep slopes where their low weight makes them more efficient and able to put in repeated acceleration runs. Their endurance also makes them good stage race specialists. Marco Pantani, champion of the 1998 Tour de France, was able to make attack after attack to quickly tire out his opponents.

Another type of rider or puncheur has a similarly small physique but possess more power which may provide an advantage in short but steep climbs in races including the Ardennes classics. Examples of such hills include the Mur de Huy in the Flèche Wallonne and the Cauberg in the Amstel Gold Race. Examples of such riders include Julian Alaphilippe, Philippe Gilbert, Paolo Bettini and Danilo Di Luca, who are able to sprint their way up the shorter climbs to win a stage or a single-day race. However, their lower endurance is a disadvantage in stage races where the climbs are usually longer, albeit at lower gradients. Many climbers cannot sprint very well because their relative small size does not allow them to match the strength of the bigger, more muscular sprinters.

The last type of climber is the breakaway specialist who can ride aggressively with many attacks and sustain their lead over ascents, descents, and flats. Famous examples include Laurent Jalabert and Richard Virenque both of whom earned their King of the Mountains jerseys in the Tour de France by day-long breakaways amassing points at every summit. Most notably, Laurent Jalabert started his career as a sprinter but later transformed himself into a different type of rider. Rafał Majka won the Polka Dot jersey at the 2014 Tour de France and 2016 Tour de France in a similar manner.

Many riders who are primarily time-trialists have also been able to compete in everything but the steepest climbs because of their good power-to-weight ratio. Tour de France winners Miguel Induráin, Jan Ullrich and Bradley Wiggins were primarily time-trialists but were also among the best in the mountain stages during the years in which they won the Tour de France. Also riders can build up a lead in the individual time trial's and defend the lead they have in the mountain stages, Tom Dumoulin won the 2017 Giro d'Italia and Primož Roglič won the 2021 Vuelta a España by doing this.

Climbing physics and physiology
Sports physiologists have attributed the advantage that small stature holds in cycling up steep ascents to the way in which body mass and body surface area scale according to height (see square–cube law). As a hypothetical cyclist's height increases, the surface areas of his body increase according to the square of his height whereas the mass of his body increases according to the cube of his height. The surface area relation applies not only to the total surface area of the body, but also to the surface areas of the lungs and blood vessels, which are primary factors in determining aerobic power. Thus, an equally proportioned cyclist who has 50% more body mass (i.e. is 50% heavier) will generate only about 30% more aerobic power. On a steep climb most of the cyclist's energy goes into lifting his own weight, so the heavier cyclist will be at a competitive disadvantage. There is, of course, a lower limit to the benefit of small stature because, among other factors, the cyclist must also lift the weight of his bicycle. The additional power is proportional to the grade or slope of the road and the speed of the rider along the slope (or along the level line). For a 5% grade, each meter of road requires lifting the body weight by 5 cm. The power (watts) is equal to change in gravitational potential energy (joules) per unit time (seconds). For a 60 kg rider, the additional power needed is about 30 watts per meter/second of road speed (about 8 watts per km/hour).

Scaling factors also account for the relative disadvantage of the small cyclist in descending, although this is a result of physics, not physiology. A larger rider will be subject to a greater gravitational force because of their greater body mass. Additionally, as mentioned, the frontal area that creates aerodynamic drag increases only quadratically with the rider's size, and hence the larger rider would be expected to accelerate faster and attain a greater terminal velocity.

Although these factors might seem to cancel each other out, the climber still has an advantage on a course with long ascents and long descents: adding several miles per hour on a slow, time-consuming climb is much more valuable than the same increase on a fast and brief descent. Any rider, of course, can improve their climbing speed by increasing their aerobic power and reducing their body weight and can increase their descending speed through better bike handling and the willingness to accept an increased risk of crashing. One of the few elite riders to use descending skill as a competitive advantage is Paolo Savoldelli, nicknamed "the falcon."

For a more quantitative treatment of climbing physics and physiology, see Swain, DP, Cycling: Uphill and Downhill.

Bicycle technology
Recent advances in bicycle components give the rider a wider range of gearing choices, allowing climbing specialists to use lower gears to ascend optimally while still having the higher gears necessary to keep up with other riders in the flatter sections. Legendary climbers of the past such as Lucien Van Impe had to ride out of the saddle pushing high gears for hours at a time; climbers today are better able to match their gearing to the challenge and climb at a more reasonable cadence. The current UCI minimum limit for the mass of bicycles is 6.8 kg. Although many bike manufacturers can create bikes much lighter than this, the UCI deems this weight fair in the spirit of preserving the 'primacy of man' over his equipment.

King of the Mountains in stage races
Most stage races have a special category for the best climber, usually by awarding points at the important summits of the race. In the Tour de France for example, the best climber, or "King of the Mountains", is awarded a red polka dot jersey (French: maillot à pois rouges). In the Giro d'Italia the best climber is awarded a blue jersey (Italian: maglia azzurra). In the Vuelta a España the best climber is awarded a blue polka dot jersey.

Active riders

 * 🇧🇪 Remco Evenepoel
 * 🇵🇱 Rafał Majka
 * 🇸🇮 Tadej Pogačar
 * 🇩🇰 Jonas Vingegaard
 * Sepp Kuss

Former riders

 * 🇺🇸 Lance Armstrong
 * 🇵🇹 José Azevedo
 * 🇪🇸 Federico Bahamontes
 * Ivan Basso
 * Gino Bartali
 * 🇪🇸 Alberto Contador
 * Fausto Coppi
 * 🇱🇺 Charly Gaul
 * 🇪🇸 Roberto Heras
 * 🇨🇴 Luis Herrera
 * 🇫🇷 Laurent Jalabert
 * 🇪🇸 Julio Jiménez
 * Vincenzo Nibali
 * Marco Pantani
 * 🇩🇰 Michael Rasmussen
 * 🇪🇸 Joaquim Rodríguez
 * 🇱🇺 Andy Schleck
 * Gilberto Simoni
 * 🇧🇪 Lucien Van Impe
 * 🇫🇷 Richard Virenque

title: Climbing specialist


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Thermal-neutron reactor

A thermal-neutron reactor is a nuclear reactor that uses slow or thermal neutrons. ("Thermal" does not mean hot in an absolute sense, but means in thermal equilibrium with the medium it is interacting with, the reactor's fuel, moderator and structure, which is much lower energy than the fast neutrons initially produced by fission.)

Most nuclear power plant reactors are thermal reactors and use a neutron moderator to slow neutrons until they approach the average kinetic energy of the surrounding particles, that is, to reduce the speed of the neutrons to low-velocity, thermal neutrons. Neutrons are uncharged, this allows them to penetrate deep in the target and close to the nuclei, thus scattering neutrons by nuclear forces, some nuclides are scattered large.

The nuclear cross section of uranium-235 for slow thermal neutrons is about 1000 barns, while for fast neutrons it is in the order of 1 barn. Therefore, thermal neutrons are more likely to cause uranium-235 to nuclear fission than to be captured by uranium-238. If at least one neutron from the U-235 fission strikes another nucleus and causes it to fission, then the chain reaction will continue. If the reaction will sustain itself, it is said to be critical, and the mass of U-235 required to produce the critical condition is said to be a critical mass.

Thermal reactors consist of the following:

 * Neutron moderator to slow down the neutrons. In light water reactors and heavy water reactors it doubles as the nuclear reactor coolant.
 * Nuclear fuel, which is a fissile material, usually uranium.
 * Reactor vessel that is a pressure vessel containing the coolant and reactor core.
 * Radiation shielding to protect people and the environment from the harmful effects of ionizing radiation.
 * Containment buildings which are designed to contain the escape of radiation in an emergency.
 * Instrumentation to monitor and control the reactor's systems.

title: Thermal-neutron reactor


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Fast-neutron reactor

A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons (carrying energies above 1 MeV, on average), as opposed to slow thermal neutrons used in thermal-neutron reactors. Such a fast reactor needs no neutron moderator, but requires fuel that is relatively rich in fissile material when compared to that required for a thermal-neutron reactor. Around 20 land based fast reactors have been built, accumulating over 400 reactor years of operation globally. The largest was the Superphénix sodium cooled fast reactor in France that was designed to deliver 1,242 MWe. Fast reactors have been studied since the 1950s, as they provide certain advantages over the existing fleet of water-cooled and water-moderated reactors. These are:
 * More neutrons are produced when fission occurs, resulting from the absorption of a fast neutron, than the comparable process with slow (thermal, or moderated) neutrons. Thus, criticality is easier to attain than with slower neutrons.
 * All fast reactor designs built to this date use liquid metals as coolants, such as the sodium-cooled fast reactor and the lead-cooled fast reactor. As the boiling points of these metals are very high, the pressure in the reactor can be maintained at a low level, which improves safety considerably.
 * As temperatures in the core can also be substantially higher than in a water cooled design, such reactors have a greater thermodynamic efficiency; a larger percentage of the heat generated is turned into usable electricity.
 * Atoms heavier than uranium have a much greater chance of fission with a fast neutron, than with a thermal one. This means that the inventory of heavier atoms in the nuclear waste stream, for example curium, is greatly reduced, leading to a substantially lower waste management requirement.

In the GEN IV initiative, about two thirds of the proposed reactors for the future use a fast spectrum for these reasons.

Fission processes
Fast reactors operate by the fission of uranium and other heavy atoms, similar to thermal reactors. However, there are crucial differences, arising from the fact that by far most commercial nuclear reactors use a moderator, and fast reactors do not.

Moderators in conventional nuclear reactors
Natural uranium consists mostly of two isotopes:

 * 99.3% uranium-238
 * 0.7% uranium-235

Of these two, undergoes fission only by fast neutrons. About 0.7% of natural uranium is, which will fission by both fast and slow (thermal) neutrons. When the uranium undergoes fission, it releases neutrons with a high energy ("fast"). However, these fast neutrons have a much lower probability of causing another fission than neutrons which are slowed down after they have been generated by the fission process. Slower neutrons have a much higher chance (about 585 times greater) of causing a fission in than the fast neutrons.

The common solution to this problem is to slow the neutrons down using a neutron moderator, which interacts with the neutrons to slow them. The most common moderator is ordinary water, which acts by elastic scattering until the neutrons reach thermal equilibrium with the water (hence the term "thermal neutron"), at which point the neutrons become highly reactive with the. Other moderators include heavy water, beryllium and graphite. The elastic scattering of the neutrons can be likened to the collision of two ping pong balls; when a fast ping pong ball hits one that is stationary or moving slowly, they will both end up having about half of the original kinetic energy of the fast ball. This is in contrast to a fast ping pong ball hitting a bowling ball, where the ping pong ball keeps virtually all of its energy.

Such thermal neutrons are more likely to be absorbed by another heavy element, such as, or. In this case, only the has a high probability of fission.

Although undergoes fission by the fast neutrons released in fission about 11% of the time this can not sustain the chain reaction alone. Neutrons produced by fission of have lower energies than the original neutron, usually below 1 MeV, the fission threshold to cause subsequent fission of, so fission of  does not sustain a nuclear chain reaction. When hit by thermal neutrons (i.e. neutrons that have been slowed down by a moderator) the neutron can be captured by the nucleus to transmute the uranium into uranium-239 which rapidly decays into neptunium-239 which in turn decays into plutonium-239. has a thermal neutron cross section larger than that of.

About 73% of the created this way will undergo fission from capturing a thermal neutron while the remaining 27% absorbs a thermal neutron without undergoing fission,  is created, which rarely fissions with thermal neutrons. When plutonium-240 in turn absorbs a thermal neutron to become a heavier isotope which is also fissionable with thermal neutrons very close in probability to plutonium-239. In a fast spectrum reactor all three isotopes have a high probability of fission when absorbing a high energy neutron which limits their accumulation in the fuel.

These effects combined have the result of creating, in a moderated reactor, the presence of the transuranic elements. Such isotopes are themselves unstable, and undergo beta decay to create ever heavier elements, such as americium and curium. Thus, in moderated reactors, plutonium isotopes in many instances do not fission (and so do not release new fast neutrons), but instead just absorb the thermal neutrons. Most moderated reactors use natural uranium or low enriched fuel. As power production continues, around 12–18 months of stable operation in all moderated reactors, the reactor both consumes more fissionable material than it breeds and accumulates neutron absorbing fission products which make it difficult to sustain the fission process. When too much fuel has been consumed the reactor has to be refueled.

Drawbacks of light water as the moderator in conventional nuclear reactors
The following disadvantages of the use of a moderator have instigated the research and development of fast reactors.

Although cheap, readily available and easily purified, light water can absorb a neutron and remove it from the reaction. It does this enough that the concentration of in natural uranium is too low to sustain the chain reaction; the neutrons lost through absorption in the water and, along with those lost to the environment, results in too few left in the fuel. The most common solution to this problem is to concentrate the amount of in the fuel to produce enriched uranium, with the leftover  known as depleted uranium.

Other thermal neutron designs use different moderators, like heavy water or graphite that are much less likely to absorb neutrons, allowing them to run on natural uranium fuel. See CANDU, X-10 Graphite Reactor. In either case, the reactor's neutron economy is based on thermal neutrons.

A second drawback of using water for cooling is that it has a relatively low boiling point. The vast majority of electricity production uses steam turbines. These become more efficient as the pressure (and thus the temperature) of the steam is higher. A water cooled and moderated nuclear reactor therefore needs to operate at high pressures to enable the efficient production of electricity. Thus, such reactors are constructed using very heavy steel vessels, for example 30 cm (12 inch) thick. This high pressure operation adds complexity to reactor design and requires extensive physical safety measures. The vast majority of nuclear reactors in the world are water cooled and moderated with water. Examples include the PWR, the BWR and the CANDU reactors. In Russia and the UK, reactors are operational that use graphite as moderator, and respectively water in Russian and gas in British reactors as coolant.

As the operational temperature and pressure of these reactors is dictated by engineering and safety constraints, both are limited. Thus, the temperatures and pressures that can be delivered to the steam turbine are also limited. Typical water temperatures of a modern pressurized water reactor are around 350 Celsius, with pressures of around 85 bar (1233 psi). Compared to for example modern coal fired steam circuits, where main steam temperatures in excess of 500 Celsius are obtained, this is low, leading to a relatively low thermal efficiency. In a modern PWR, around 30-33 % of the nuclear heat is converted into electricity.

A third drawback is that when a (any) nuclear reactor is shut down after operation, the fuel in the reactor no longer undergoes fission processes. However, there is an inventory present of highly radioactive elements, some of which generate substantial amounts of heat. If the fuel elements were to be exposed (i.e. there is no water to cool the elements), this heat is no longer removed. The fuel will then start to heat up, and temperatures can then exceed the melting temperature of the zircaloy cladding. When this occurs the fuel elements melt, and a meltdown occurs, such as the multiple meltdowns that occurred in the Fukushima disaster. When the reactor is in shutdown mode, the temperature and pressure are slowly reduced to atmospheric, and thus water will boil at 100 Celsius. This relatively low temperature, combined with the thickness of the steel vessels used, could lead to problems in keeping the fuel cool, as was shown by the Fukushima accident.

Lastly, the fission of uranium and plutonium in a thermal spectrum yields a smaller number of neutrons than in the fast spectrum, so in a fast reactor, more losses are acceptable.

The proposed fast reactors solve all of these problems (next to the fundamental fission properties, where for example plutonium-239 is more likely to fission after absorbing a fast neutron, than a slow one.)

Fast fission and breeding
Although and  have a lower capture cross section with higher-energy neutrons, they still remain reactive well into the MeV range. If the density of or  is sufficient, a threshold will be reached where there are enough fissile atoms in the fuel to maintain a chain reaction with fast neutrons. In fact, in the fast spectrum, when captures a fast neutron it will also undergo fission around 11% of the time with the remainder of captures being "radiative" and entering the decay chain to plutonium-239.

Crucially, when a reactor runs on fast neutrons, the isotope is likely to fission 74% of the time instead of the 62% of fissions when it captures a thermal neutron. In addition the probability of a upon absorbing a fast neutron fissioning is 70% while for a thermal neutron it is less than 20%. Fast neutrons have a smaller chance of being captured by the uranium and plutonium, but when they are captured, have a significantly higher probability of causing a fission. The inventory of spent fast reactor fuel therefore contains virtually no actinides except for uranium and plutonium, which can be effectively recycled. Even when the core is initially loaded with 20% mass reactor-grade plutonium (containing on average 2%, 53% , 25% , 15% , 5% and traces of ), the fast spectrum neutrons are capable of causing each of these to fission at significant rates. By the end of a fuel cycle of some 24 months, these ratios will have shifted with an increase of to over 80% while all the other plutonium isotopes will have decreased in proportion.

By removing the moderator, the size of the reactor core volume can be greatly reduced, and to some extent the complexity. As and particularly  are far more likely to fission when they capture a fast neutron, it is possible to fuel such reactors with a mixture of plutonium and natural uranium, or with enriched material, containing around 20%. Test runs at various facilities have also been done using and. The natural uranium (mostly ) will be turned into, while in the case of , is the result. As new fuel is created during the operation, this process is called breeding. All fast reactors can be used for breeding, or by carefully selecting the materials in the core and eliminating the blanket they can be operated to maintain the same level of fissionable material without creating any excess material. This is a process called Conversion because it transmutes fertile materials into fissile fuels on a 1:1 basis. By surrounding the reactor core with a blanket of or  which captures excess neutrons, the extra neutrons breed more  or  respectively.

The blanket material can then be processed to extract the new fissile material, which can then be mixed with depleted uranium to produce MOX fuel, mixed with lightly enriched Uranium fuel to form REMIX fuel both for conventional slow-neutron reactors. Alternatively it can be mixed as in greater percentage of 17%-19.75% fissile fuel for fast reactor cores. A single fast reactor can thereby supply its own fuel indefinitely as well as feed several thermal ones, greatly increasing the amount of energy extracted from the natural uranium. The most effective breeder configuration theoretically is able to produce 14 nuclei for every 10 (14:10) actinide nuclei consumed, however real world fast reactors have so far achieved a ratio of 12:10 ending the fuel cycle with 20% more fissile material than they held at the start of the cycle. Less than 1% of the total Uranium mined is consumed in a thermal once-through cycle, while up to 60% of the natural uranium is fissioned in the best existing fast reactor cycles.

Given the current inventory of spent nuclear fuel (which contains reactor grade plutonium), it is possible to process this spent fuel material and reuse the actinide isotopes as fuel in a large number of fast reactors. This effectively consumes the, reactor-grade plutonium, , and. Enormous amounts of energy are still present in the spent reactor fuel inventories; if fast reactor types were to be employed to use this material, that energy can be extracted for useful purposes.

Waste recycling
Fast-neutron reactors can potentially reduce the radiotoxicity of nuclear waste. Each commercial scale reactor would have an annual waste output of a little more than a ton of fission products, plus trace amounts of transuranics if the most highly radioactive components could be recycled. The remaining waste should be stored for about 500 years.

With fast neutrons, the ratio between splitting and the capture of neutrons by plutonium and the minor actinides is often larger than when the neutrons are slower, at thermal or near-thermal "epithermal" speeds. Simply put, fast neutrons have a smaller chance of being absorbed by plutonium or uranium, but when they are, they almost always cause a fission. The transmuted even-numbered actinides (e.g., ) split nearly as easily as odd-numbered actinides in fast reactors. After they split, the actinides become a pair of "fission products". These elements have less total radiotoxicity. Since disposal of the fission products is dominated by the most radiotoxic fission products, strontium-90, which has a half life of 28.8 years, and caesium-137, which has a half life of 30.1 years, the result is to reduce nuclear waste lifetimes from tens of millennia (from transuranic isotopes) to a few centuries. The processes are not perfect, but the remaining transuranics are reduced from a significant problem to a tiny percentage of the total waste, because most transuranics can be used as fuel.

Fast reactors technically solve the "fuel shortage" argument against uranium-fueled reactors without assuming undiscovered reserves, or extraction from dilute sources such as granite or seawater. They permit nuclear fuels to be bred from almost all the actinides, including known, abundant sources of depleted uranium and thorium, and light-water reactor wastes. On average, more neutrons per fission are produced by fast neutrons than from thermal neutrons. This results in a larger surplus of neutrons beyond those required to sustain the chain reaction. These neutrons can be used to produce extra fuel, or to transmute long half-life waste to less troublesome isotopes, as was done at the Phénix reactor in Marcoule, France, or some can be used for each purpose. Though conventional thermal reactors also produce excess neutrons, fast reactors can produce enough of them to breed more fuel than they consume. Such designs are known as fast breeder reactors.

In the spent fuel from water moderated reactors, several plutonium isotopes are present, along with the heavier, transuranic elements. Nuclear reprocessing, a complex series of chemical extraction processes, mostly based on the PUREX process, can be used to extract the unchanged uranium, the fission products, the plutonium, and the heavier elements. Such waste streams can be divided in categories; 1) unchanged uranium-238, which is the vast bulk of the material and has a very low radioactivity, 2) a collection of fission products and 3) the transuranic elements.

Coolant
All nuclear reactors produce heat which must be removed from the reactor core. Water, the most common coolant in thermal reactors, is generally not feasible for a fast reactor, because it acts as an effective neutron moderator.

All operating fast reactors are liquid metal cooled reactors, which use sodium, lead, or lead-bismuth eutectic as coolants. The early Clementine reactor used mercury coolant and plutonium metal fuel. In addition to its toxicity to humans, mercury has a high capture cross section (thus, it readily absorbs the neutrons, which causes nuclear reactions) for the (n,gamma) reaction, causing activation in the coolant and losing neutrons that could otherwise be absorbed in the fuel, which is why it is no longer considered useful as a coolant.

Russia has developed reactors that use molten lead and lead-bismuth eutectic alloys, which have been used on a larger scale in naval propulsion units, particularly the Soviet Alfa-class submarine, as well as some prototype reactors. Sodium-potassium alloy (NaK) is popular in test reactors due to its low melting point.

Another proposed fast reactor is a molten salt reactor, in which the salt's moderating properties are insignificant. The particular salt formula used is crucial as some formulas are effective moderators while others are not.

Gas-cooled fast reactors have been the subject of research commonly using helium, which has small absorption and scattering cross sections, thus preserving the fast neutron spectrum without significant neutron absorption in the coolant. Purified nitrogen-15 has also been proposed as a coolant gas because it is more common than Helium and also has a very low neutron absorption cross section.

However, all large-scale fast reactors have used molten metal coolant. Advantages of molten metals are low cost, the small activation potential and the large liquid ranges. The latter means that the material has a low melting point, and a high boiling point. Examples of these reactors include Sodium cooled fast reactor, which are still being pursued worldwide. Russia currently operates two such reactors on a commercial scale. Additionally, Russia has around eighty reactor years of experience with the Lead-cooled fast reactor which is rapidly gaining interest.

Fuel
In practice, sustaining a fission chain reaction with fast neutrons means using relatively enriched uranium or plutonium. The reason for this is that fissile reactions are favored at thermal energies, since the ratio between the fission cross section and  absorption cross section is ~100 in a thermal spectrum and 8 in a fast spectrum. Fission and absorption cross sections are low for both and  at high (fast) energies, which means that fast neutrons are likelier to pass through fuel without interacting than thermal neutrons; thus, more fissile material is needed. Therefore, a fast reactor cannot run on natural uranium fuel. However, it is possible to build a fast reactor that breeds fuel by producing more than it consumes. After the initial fuel charge such a reactor can be refueled by reprocessing. Fission products can be replaced by adding natural or even depleted uranium without further enrichment. This is the concept of the fast breeder reactor or FBR.

So far, most fast-neutron reactors have used either MOX (mixed oxide) or metal alloy fuel. Soviet fast-neutron reactors used (highly enriched) uranium fuel initially, then in 2022 switched to using MOX. The Indian prototype reactor uses uranium-carbide fuel.

While criticality at fast energies may be achieved with uranium enriched to 5.5 (weight) percent, fast reactor designs have been proposed with enrichment in the range of 20 percent for reasons including core lifetime: if a fast reactor were loaded with the minimal critical mass, then the reactor would become subcritical after the first fission. Rather, an excess of fuel is inserted with reactivity control mechanisms, such that the reactivity control is inserted fully at the beginning of life to bring the reactor from supercritical to critical; as the fuel is depleted, the reactivity control is withdrawn to support continuing fission. In a fast breeder reactor, the above applies, though the reactivity from fuel depletion is also compensated by breeding either or  and  from  or, respectively. Some designs use Burnable Poisons also known as Burnable Absorbers which contain isotopes with high neutron capture cross sections. Concentrated or  &  in natural Gadolinium are typically used for this purpose. As these isotopes absorb excess neutrons they are transmuted into isotopes with low absorption cross sections so that over the life of the fuel cycle they are eliminated as more fission products with high capture cross section are generated. This makes it easier to maintain control of the reactivity rate in the core at start up with fresh fuel.

Control
Like thermal reactors, fast-neutron reactors are controlled by keeping the criticality of the reactor reliant on delayed neutrons, with gross control from neutron-absorbing control rods or blades.

They cannot, however, rely on changes to their moderators because there is no moderator. So Doppler broadening in the moderator, which affects thermal neutrons, does not work, nor does a negative void coefficient of the moderator. Both techniques are common in ordinary light-water reactors.

Doppler broadening from the molecular motion of the fuel, from its heat, can provide rapid negative feedback. The molecular movement of the fissionables themselves can tune the fuel's relative speed away from the optimal neutron speed. Thermal expansion of the fuel can provide negative feedback. Small reactors as in submarines may use Doppler broadening or thermal expansion of neutron reflectors.

Resources
As the perception of the reserves of uranium ore in the 1960s was rather low, and the rate that nuclear power was expected to take over baseload generation, through the 1960s and 1970s fast breeder reactors were considered to be the solution to the world's energy needs. Using twice-through processing, a fast breeder increases the energy capacity of known ore deposits, meaning that existing ore sources would last hundreds of years. The disadvantage to this approach is that the breeder reactor has to be fed fuel that must be treated in a spent fuel treatment plant. It was widely expected that this would still be below the price of enriched uranium as demand increased and known resources dwindled.

Through the 1970s, experimental breeder designs were examined, especially in the US, France and the USSR. However, this coincided with a crash in uranium prices. The expected increased demand led mining companies to expand supply channels, which came online just as the rate of reactor construction stalled in the mid-1970s. The resulting oversupply caused fuel prices to decline from about US$40 per pound in 1980 to less than $20 by 1984. Breeders produced fuel that was much more expensive, on the order of $100 to $160, and the few units that reached commercial operation proved to be economically unfeasible.

Advantages
Fast reactors are widely seen as an essential development because of several advantages over moderated designs. The most studied and built fast reactor type is the sodium-cooled fast reactor. Some of the advantages of this design are discussed below; other designs such as the lead-cooled fast reactor and FMSR, Fast Molten Salt Reactor have similar advantages.

 * A fission event creates more neutrons than in the thermal reactor. This gives flexibility and allows breeding of uranium or thorium.
 * As absorbing a fast neutron has an 11% probability of fissioning, a significant percentage of the fission events in the reactor occur with this isotope.
 * There is a fine balance between the production of neutrons from fission on the one hand, and the many processes that remove them from the equation on the other. If the temperature increases in a fast reactor, this will have two effects:
 * Doppler broadening of the neutron spectrum, and
 * a very small increase in the physical size of the reactor core.
 * These two effects serve to reduce the reactivity because it allows more neutrons to escape the core, as was shown in a demonstration at EBR-II in 1986. In this test, the additional heat was readily absorbed by the large volume of liquid sodium, and the reactor shut itself down, without operator intervention.

 * Because sodium has a boiling point of 883 Celsius, and lead has a boiling point of 1749 Celsius but reactors operates typically around 500 Celsius to 550 Celsius, there is a large margin where the metals will stay liquid, and thermal increases can be easily absorbed, without any pressure increase. For the Chloride salts typically used in fast molten salt reactor designs the Sodium Chloride has a boiling point of 1,465 Celsius
 * As no water is present in the core at high temperatures, the reactor is essentially at atmospheric pressure. Most often, an inert gas blanket at a modest pressure (e.g. 0.5 atmospheres) is present to ensure that any leak results in mass transport to the outside of the reactor. This means that there is no pressure vessel with associated problems (high pressure systems are complex), nor will a leak from the reactor emit high pressure jets.
 * The entire vessel being at atmospheric pressure, and the sodium is very hot, and can be allowed to remain at these temperatures even in shutdown, passive cooling (i.e. no pumping requirements) with air is possible. Accidents such as the Fukushima Daiichi nuclear accident are impossible with such a design.
 * The higher temperature of the liquid metal or salt, and therefore the higher temperature of the steam generated by this coolant, allows a considerable increase in the electric generating efficiency (around 40% thermal efficiency, as opposed to 30%).
 * Such reactors have the potential to significantly reduce the waste streams from nuclear power, while at the same time increasing vastly the fuel utilization.

Disadvantages
As most fast reactors to date have been either sodium, lead or lead-bismuth cooled, the disadvantages of such systems are described here.

 * As a result of running the reactors on fast neutrons, the reactivity of the core is determined by these neutrons, as opposed to moderated reactors. In the moderated reactors, a significant amount of control of the reactivity is obtained from delayed neutrons, which allow time for operators or computers to adjust reactivity. As delayed neutrons play virtually no role in fast reactors, other mechanisms are required for the very short term reactivity control (e.g. within one second) in fast reactors, which are thermal expansion and Doppler broadening. Longer term reactivity is obtained from control rods, which are filled with a neutron absorption material.
 * As the entire reactor is filled with large volumes of molten metal, refuelling is not trivial, as optical tools (cameras, etc.) are of no use. Costly, carefully calibrated and positioned robotic tools are needed for the operation of refueling. Also, completely removing fuel elements from the reactor is not easy.
 * The fact that the entire reactor is filled with a metal that has a melting point much higher than room temperature, all the tubing, heat exchangers, and the entire reactor volume must be heated electrically, before any nuclear operation can take place. However, once the reactor produces heat, this is no longer of any concern.
 * To date most fast reactor types have proven costly to build and operate, and are not very competitive with thermal-neutron reactors unless the price of uranium increased dramatically, or building costs decreased. It is thought that given the perception of problematic nuclear waste disposal, such reactors will be necessary. As moderated reactor construction costs are rising (among other) due to ever more stringent safety mechanisms, this could mean a better economic viability of fast reactors.
 * Sodium is often used as a coolant in fast reactors, because it does not moderate neutron speeds much and has a high heat capacity. However, it burns and foams in air, although the combustion reaction of sodium in air should not be confused with the extremely violent reaction of sodium and water. Sodium leaks can ignite with air, causing difficulties in reactors such as (e.g. USS Seawolf (SSN-575) and Monju).
 * Some sodium-cooled fast reactors have operated safely for long periods (notably the Phénix and EBR-II for 30 years, or the BN-600 and BN-800 in operation since resp. 1980 and 2016, despite several minor leaks and fires. It is important to note that sodium leaks (and possibly fires) do not release radioactive elements, as the sodium fast reactors are always designed with a two loop system.

 * Since liquid metals other than lithium and beryllium have low moderating ability, the primary interaction of neutrons with fast reactor coolant is the (n,gamma) reaction, which induces radioactivity in the coolant. Sodium-24 is created in the reactor loop of the sodium cooled fast reactor, from natural sodium-23 by neutron bombardment. With a 15-hour half-life,  decays to  by emission of an electron and two gamma rays. As the half life of this isotope is very short, after e.g. two weeks, almost no  is left. Fast spectrum reactors that use sodium must remove this magnesium from the sodium, which is achieved with a 'cold' trap.
 * From the liquid lead or Lead-bismuth eutectic designs, only the liquid eutectic lead-bismuth will have activation. As pure lead will have virtually no activation, a pure lead reactor design could operate in a single loop, saving significant costs on heat exchanger and separate systems.
 * A defective fast reactor design could have positive void coefficient: boiling of the coolant in an accident would reduce coolant density and thus the absorption rate. No such designs are proposed for commercial service, as they are potentially dangerous and undesirable from a safety and accident standpoint. This can be avoided with a gas-cooled reactor, since voids do not form in such a reactor during an accident; however, reactivity control in a gas cooled fast reactor is difficult.
 * Due to the low cross sections of most materials at high neutron energies, critical mass in a fast reactor is much higher than in a thermal reactor. In practice, this means significantly higher enrichment: >20% enrichment in a fast reactor compared to <5% enrichment in typical thermal reactors. Alternatively, a mixture of plutonium from nuclear waste, combined with natural or depleted uranium could be used.

History

US interest in breeder reactors were muted by Jimmy Carter's April 1977 decision to defer construction of breeders in the US due to proliferation concerns, and the suboptimal operating record of France's Superphénix reactor. The French reactors also met with serious opposition of environmentalist groups, who regarded these as very dangerous. Despite such setbacks, a number of countries still invest in the fast reactor technology. Around 25 reactors have been built since the 1970s, accumulating over 400 reactor years of experience.

A 2008 IAEA proposal for a Fast Reactor Knowledge Preservation System noted that: during the past 15 years there has been stagnation in the development of fast reactors in the industrialized countries that were involved, earlier, in intensive development of this area. All studies on fast reactors have been stopped in countries such as Germany, Italy, the United Kingdom and the United States of America and the only work being carried out is related to the decommissioning of fast reactors. Many specialists who were involved in the studies and development work in this area in these countries have already retired or are close to retirement. In countries such as France, Japan and the Russian Federation that are still actively pursuing the evolution of fast reactor technology, the situation is aggravated by the lack of young scientists and engineers moving into this branch of nuclear power.

As of 2021, Russia operates two fast reactors on commercial scale. The GEN IV initiative, an international working group on new reactor designs has proposed six new reactor types, three of which would operate with a fast spectrum.

United States

 * Clementine was the first fast reactor, built in 1946 at Los Alamos National Laboratory. It used plutonium metal fuel, mercury coolant, achieved 25 kW thermal and used for research, especially as a fast neutron source.
 * Experimental Breeder Reactor I (EBR-I) at Argonne West, now Idaho National Laboratory, near Arco, Idaho, in 1951 became the first reactor to generate significant amounts of power. Decommissioned in 1964.
 * Fermi 1 near Detroit was a prototype fast breeder reactor that powered up in 1957 and shut down in 1972.
 * Experimental Breeder Reactor II (EBR-II) at Idaho National Laboratory, near Arco, Idaho, was a prototype for the Integral Fast Reactor, 1965–1994.
 * SEFOR in Arkansas, was a 20 MWt research reactor that operated from 1969 to 1972.
 * Fast Flux Test Facility (FFTF), 400 MWt, operated flawlessly from 1982 to 1992, at Hanford Washington. It used liquid sodium drained with argon backfill under care and maintenance.
 * SRE in California, was a 20 MWt, 6.5 MWe commercial reactor operated from 1957 to 1964.
 * LAMPRE-1 was a molten plutonium fueled 1 MWth reactor. It operated as a research reactor from 1961 to 1963 at Los Alamos national Lab.

Europe

 * Dounreay Loop type Fast Reactor (DFR), 1959–1977, was a 14 MWe and Prototype Fast Reactor (PFR), 1974–1994, 250 MWe, in Caithness, in the Highland area of Scotland.
 * Dounreay Pool type Fast Reactor (PFR), 1975–1994, was a 600 MWt, 234 MWe which used mixed oxide (MOX) fuel.
 * Rapsodie in Cadarache, France, (20 then 40 MW) operated between 1967 and 1982.
 * Superphénix, in France, 1200 MWe, closed in 1997 due to a political decision and high costs.
 * Phénix, 1973, France, 233 MWe, restarted 2003 at 140 MWe for experiments on transmutation of nuclear waste for six years, ceased power generation in March 2009, though it will continue in test operation and to continue research programs by CEA until the end of 2009. Stopped in 2010.
 * KNK-II, in Germany a 21 MWe experimental compact sodium-cooled fast reactor operated from Oct 1977-Aug 1991. The objective of the experiment was to eliminate nuclear waste while producing energy. There were minor sodium problems combined with public protests which resulted in the closure of the facility.

USSR/Russia

 * Small lead-cooled fast reactors were used for naval propulsion, particularly by the Soviet Navy.
 * BR-5 - was a research-focused fast-neutron reactor at the Institute of Physics and Energy in Obninsk from 1959 to 2002.
 * BN-350 was constructed by the Soviet Union in Shevchenko (today's Aqtau) on the Caspian Sea, It produced 130 MWe plus 80,000 tons of fresh water per day.
 * IBR was a research-focused pulsed fast-neutron reactor at the Joint Institute of Nuclear Research in Dubna (near Moscow) put into operation in 1984 till 2006.
 * RORSATs - 33 space fast reactors were launched by the Soviet Union from 1989 to 1990 as part of a program known as the Radar Ocean Reconnaissance Satellite (RORSAT) in the US. Typically, the reactors produced approximately 3 kWe.
 * BES-5 - was a sodium cooled space reactor launched as part of the RORSAT program which produced 5 kWe.
 * BR-5 - was a 5 MWt sodium fast reactor operated by the USSR in 1961 primarily for materials testing.
 * Russian Alpha 8 PbBi - was a series of lead-bismuth cooled fast reactors used aboard submarines. The submarines functioned as killer submarines, staying in harbor then attacking due to the high speeds achievable by the sub.

Asia

 * Monju reactor, 300 MWe, in Japan, was closed in 1995 following a serious sodium leak and fire. It was restarted on May 6, 2010, but in August 2010 another accident, involving dropped machinery, shut down the reactor again. As of June 2011, the reactor had generated electricity for only one hour since its first test two decades prior.
 * Aktau Reactor, 150 MWe, in Kazakhstan, was used for plutonium production, desalination, and electricity. It closed 4 years after the plant's operating license expired.

Never operated

 * Clinch River Breeder Reactor, United States
 * Integral Fast Reactor, United States. Design emphasized fuel cycle based on on-site electrolytic reprocessing. Cancelled in 1994 without construction.
 * SNR-300, Germany

Active

 * IBR-2 - a pulsed fast-neutron reactor at Joint Institute for Nuclear Research in Dubna. Located at the Laboratory of Neutron Physics (FLNP) named after. I.M. Frank as part of JINR. From 2006 to June 2011 it underwent modernization. The only nuclear reactor in the world with a movable reflector. Commissioned on February 10, 1984.
 * BN-600 - a pool type sodium-cooled fast breeder reactor at the Beloyarsk Nuclear Power Station. It provides 560 MWe to the Middle Urals power grid. In operation since 1980.
 * BN-800 - a sodium-cooled fast breeder reactor at the Beloyarsk Nuclear Power Station. It generates 880 MW of electrical power and started producing electricity in October, 2014. It reached full power in August, 2016.
 * BOR-60 - a sodium-cooled reactor at the Research Institute of Atomic Reactors in Dimitrovgrad, Russia. In operation since 1968. It produces 60MW for experimental purposes.
 * FBTR - a 40MWt,13.2MWe experimental reactor in India which focused on reaching significant burnup levels.
 * China Experimental Fast Reactor, a 60 MWth, 20 MWe, experimental reactor which went critical in 2011 and is currently operational. It is used for materials and component research for future Chinese fast reactors.
 * KiloPower/KRUSTY is a 1-10 kWe research sodium fast reactor built at Los Alamos National Laboratory. It first reach criticality in 2015 and demonstrates an application of a Stirling power cycle.

Under repair

 * Jōyō (常陽), 1977–1997 and 2004–2007, Japan, 140 MWt is an experimental reactor, operated as an irradiation test facility. After an incident in 2007, the reactor was suspended for repairing, recoworks were planned to be completed in 2014.

Under construction

 * PFBR, Kalpakkam, India, 500 MWe reactor with criticality planned for 2021. It is a sodium fast breeder reactor.
 * CFR-600, China, 600 MWe.
 * MBIR Multipurpose fast neutron research reactor. The Research Institute of Atomic Reactors (NIIAR) site at Dimitrovgrad in the Ulyanovsk region of western Russia, 150 MWt. Construction started in 2016 with completion scheduled for 2024.
 * BREST-300, Seversk, Russia. Construction started at 8 June 2021

In design

 * BN-1200, Russia, built starting after 2014, with operation planned for 2018–2020, now delayed until at least 2035.
 * Toshiba 4S was planned to be shipped to Galena, Alaska (USA) but progress stalled (see Galena Nuclear Power Plant)
 * KALIME is a 600 MWe project in South Korea, projected for 2030. KALIMER is a continuation of the sodium-cooled, metal-fueled, fast-neutron reactor in a pool represented by the Advanced Burner Reactor (2006), S-PRISM (1998-present), Integral Fast Reactor (1984-1994), and EBR-II (1965-1995).
 * Generation IV reactor (helium·sodium·lead cooled) US-proposed international effort, after 2030.
 * JSFR, Japan, a project for a 1500 MWe reactor began in 1998, but without success.
 * ASTRID, France, canceled project for a 600 MWe sodium-cooled reactor.
 * Mars Atmospherically Cooled Reactor (MACR) is a 1 MWe project, planned to complete in 2033. MACR is a gas-cooled (carbon dioxide coolant) fast-neutron reactor intended to provide power to proposed Mars colonies.
 * TerraPower is designing a molten salt reactor in partnership with Southern Company, Oak Ridge National Laboratory, Idaho National Laboratory, Vanderbilt University and the Electric Power Research Institute. They expect to begin testing a loop facility in 2019 and is scaling up their salt manufacturing process. Data will be used to assess thermal hydraulics and safety analysis codes.
 * Elysium Industries is designing a fast spectrum molten salt reactor.
 * ALFRED (Advanced Lead Fast Reactor European Demonstrator) is a lead cooled fast reactor demonstrator designed by Ansaldo Energia from Italy, it represents the last stage of the ELSY and LEADER projects.
 * Aurora nuclear reactor, Idaho

Planned

 * Future FBR, India, 600 MWe, after 2025

title: Fast-neutron reactor


text:
Gian Francesco Malipiero

Gian Francesco Malipiero (18 March 1882 – 1 August 1973) was an Italian composer, musicologist, music teacher and editor.

Early years
Born in Venice into an aristocratic family, the grandson of the opera composer Francesco Malipiero, Gian Francesco Malipiero was prevented by family troubles from pursuing his musical education in a consistent manner. His father separated from his mother in 1893 and took Gian Francesco to Trieste, Berlin and eventually to Vienna. The young Malipiero and his father broke up their relationship bitterly, and in 1899 Malipiero returned to his mother's home in Venice, where he entered the Venice Liceo Musicale (now the Conservatorio di Musica Benedetto Marcello di Venezia).

After stopping counterpoint lessons with the composer, organist and pedagogue Marco Enrico Bossi, Malipiero continued studying on his own by copying out music by such composers as Claudio Monteverdi and Girolamo Frescobaldi from the Biblioteca Marciana, in Venice, thereby beginning a lifelong commitment to Italian music of that period. In 1904 he went to Bologna and sought out Bossi to continue his studies, at the Bologna Liceo Musicale (now the Conservatorio Giovanni Battista Martini). In 1906 he returned to the Venice Conservatory Benedetto Marcello of Music to continue his studies. After graduating, Malipiero became an assistant to the blind composer Antonio Smareglia.

Musical career
In 1905 Malipiero returned to Venice, but from 1906 to 1909 was often in Berlin, following Max Bruch's classes. Later, in 1913, Malipiero moved to Paris, where he became acquainted with compositions by Ravel, Debussy, Falla, Schoenberg, and Berg. Most importantly, he attended the première of Stravinsky's Le Sacre du Printemps, soon after meeting Alfredo Casella and Gabriele d'Annunzio. He described the experience as an awakening "from a long and dangerous lethargy". After that, he repudiated almost all the compositions he had written up to that time, with the exception of Impressioni dal vero (1910–11). At that time he won four composition prizes at the Accademia Nazionale di Santa Cecilia in Rome, by entering five compositions under five different pseudonyms.

In 1917, due to the Italian defeat at Caporetto, he was forced to flee from Venice and settled in Rome.

In 1923, he joined with Alfredo Casella and Gabriele D'Annunzio in creating the Corporazione delle Nuove Musiche. Malipiero was on good terms with Benito Mussolini until he set Pirandello's libretto La favola del figlio cambiato, earning the condemnation of the fascists. Malipiero dedicated his next opera, Giulio Cesare, to Mussolini, but this did not help him.

He was a professor of composition at the Parma Conservatory from 1921 to 1924. In 1932 he became professor of composition at the then Venice Liceo Musicale, which he directed from 1939 to 1952. Among others, he taught Luigi Nono and his own nephew Riccardo Malipiero.

After permanently settling in the little town of Asolo in 1923, Malipiero began the editorial work for which he would become best known, a complete edition of all of Claudio Monteverdi's oeuvre, from 1926 to 1942, and after 1952, editing much of Vivaldi's concerti at the Istituto Italiano Antonio Vivaldi.

Compositions
Malipiero had an ambivalent attitude towards the musical tradition dominated by Austro-German composers, and instead insisted on the rediscovery of pre-19th-century Italian music.

His orchestral works include seventeen compositions he called symphonies, of which however only eleven are numbered. The first was composed in 1933, when Malipiero was already over fifty years old. Prior to that, Malipiero had written several important orchestral pieces but avoided the word "sinfonia" (symphony) almost completely. This was due to his rejection of the Austro-German symphonic tradition. The only exceptions to that are the three compositions Sinfonia degli eroi (1905), Sinfonia del mare (1906) and Sinfonie del silenzio e della morte (1909–1910). In such early works, the label "symphony" should not, however, be interpreted as indicating works in the Beethovenian or Brahmsian symphonic style, but more as symphonic poems.

When asked in the mid-1950s by the British encyclopedia The World of Music, Malipiero listed as his most important compositions the following pieces:

 * Pause del Silenzio for the orchestra, composed in 1917
 * Rispetti e Strambotti for string quartet, composed in 1920
 * L'Orfeide for the stage, composed between 1918 and 1922, and first performed in 1924
 * La Passione, a mystery play composed in 1935
 * his nine symphonies, composed between 1933 and 1955 (he would compose additional symphonies in the years after this list was made)

He regarded Impressioni dal vero, for orchestra, as his earliest work of lasting importance.

Musical theory and style
Malipiero was strongly critical of sonata form and, in general, of standard thematic development in composition. He declared:

As a matter of fact I rejected the easy game of thematic development because I was fed up with it and it bored me to death. Once one finds a theme, turns it around, dismembers it and blows it up, it is not very difficult to assemble the first movement of a symphony (or a sonata) that will be amusing for amateurs and also satisfy the lack of sensitivity of the knowledgeable.

Malipiero's musical language is characterized by an extreme formal freedom; he always renounced the academic discipline of variation, preferring the more anarchic expression of song, and he avoided falling into program music descriptivism. Until the first half of the 1950s, Malipiero remained tied to diatonism, maintaining a connection with the pre-19th-century Italian instrumental music and Gregorian chant, moving then slowly to increasingly eerie and tense territories that put him closer to total chromaticism. He did not abandon his previous style but he reinvented it. In his latest pages, it is possible to recognize suggestions from his pupils Luigi Nono and Bruno Maderna.

His compositions are based on free, non-thematic passages as much as in thematic composition, and seldom do movements end in the keys in which they started.

When Malipiero approached the symphony, he did not do so in the so-called post-Beethovenian sense, and for this reason authors rather described his works as "sinfonias" (the Italian term), to emphasize Malipiero's fundamentally Italian, anti-Germanic approach. He remarked:

The Italian symphony is a free kind of poem in several parts which follow one another capriciously, obeying only those mysterious laws that instinct recognizes

As Ernest Ansermet once declared, "these symphonies are not thematic but 'motivic': that is to say Malipiero uses melodic motifs like everyone else [...] they generate other motifs, they reappear, but they do not carry the musical discourse – they are, rather, carried by it".

Reception
The French conductor Antonio de Almeida led the Moscow Symphony Orchestra in recordings of the complete Malipiero symphonies for Naxos (Marco Polo, 1993–1994).

Recently, Malipiero's piano repertoire, including his complete concertos, has experienced a revival at the hands of noted Italian pianist Sandro Ivo Bartoli.

Malipiero was the subject of the 1985 biographical film Poems of Asolo by Georg Brintrup.

Operas

 * L'Orfeide (1919–1922, Düsseldorf 1925), in tre parti:
 * I "La morte delle maschere",
 * II "Sette canzoni",
 * III "Orfeo"

 * Tre commedie goldoniane (1920–1922, Darmstadt 1926) :
 * I "La bottega da caffè",
 * II "Sior Todero Brontolon",
 * III "Le baruffe Chiozotte"

 * Filomela e l'infatuato (1925, Prague 1928)
 * Torneo notturno (1929)
 * La favola del figlio cambiato (libretto di Luigi Pirandello, 1933)
 * Giulio Cesare (da Shakespeare (1935, Genoa 1936)
 * Antonio e Cleopatra (da Shakespeare, 1937, Florence 1938)
 * I capricci di Callot (da E.T.A. Hoffmann, 1942, Rome 1942)
 * L'allegra brigata (1943, Milan 1950)
 * Mondi celesti ed infernali (1949, Venice 1961)
 * Il figliuol prodigo (1952, Florence 1957)
 * Donna Urraca, atto unico (1954)
 * Venere prigioniera (1955, Florence 1957)
 * Il marescalco (1960, Treviso 1969)
 * Don Giovanni (1963, Naples)
 * Rappresentazione e festa di Carnasciale e della Quaresima (Opera balletto, 1961, Venice 1970)
 * Le metamorfosi di Bonaventura (Venice 1966)
 * Don Tartufo bacchettone (1966, Venice 1970)
 * Iscariota (1971)

Orchestral music

 * Dai sepolcri (1904)
 * Sinfonia degli eroi (1905)
 * Sinfonia del mare (1906)
 * Sinfonia del silenzio e de la morte (1909–1910)
 * Impressioni dal vero prima parte (1910)
 * Impressioni dal vero seconda parte (1915)
 * Ditirambo tragico (1917)
 * Pause del Silenzio (1917)
 * Grottesco (1918)
 * Ballet Pantea (1919)
 * Cimarosiana (1921), five symphonic fragments from keyboard works of Cimarosa
 * Impressioni dal vero terza parte (1922)
 * Concerti (1931)
 * Concerto n.1 for Piano and Orchestra (1931)
 * Inni (1932)
 * Concerto n.1 for Violin and Orchestra (1932)
 * Sette Invenzioni (1933)
 * Sinfonia n.1 "In quattro tempi, come le quattro stagioni" (1933)
 * Sinfonia n.2 "Elegiaca" (1936)
 * Concerto for Cello and Orchestra (1937)
 * Concerto n.2 for Piano and Orchestra (1937)
 * Concerto a tre for Violin, Cello, Piano and Orchestra (1938)
 * Sinfonia n.3 "Delle campane" (1944–1945)
 * Sinfonia n.4 "In memoriam" (1946)
 * Sinfonia n.5 "Concertante in eco" (1947)
 * Sinfonia n.6 "Degli archi" (1947)
 * Ballet Stradivario (1948)
 * Sinfonia n.7 "Delle canzoni" (1948)
 * Concerto n.3 per pianoforte e orchestra (1948)
 * Concerto n.4 per pianoforte e orchestra (1950)
 * Sinfonia in un tempo (1950)
 * Sinfonia dello Zodiaco "Quattro partite: dalla primavera all'inverno" (1951)
 * Ballet El mondo novo (1951)
 * Vivaldiana (1952)
 * Passacaglie (1952)
 * Fantasie di ogni giorno (1953)
 * Elegia capriccio (1953)
 * Fantasie concertanti (1954)
 * Notturno di canti e balli (1957)
 * Concerto n.5 for Piano and Orchestra (1958)
 * Sinfonia per Antigenida (1962)
 * Concerto n.2 for Violin and Orchestra (1963)
 * Sinfonia n.8 "Symphonia brevis" (1964)
 * Concerto n.6 for Piano and Orchestra (1964)
 * Sinfonia n.9 "Dell'Ahimè" (1966)
 * Sinfonia n.10 "Atropo" (1966–1967)
 * Concerto per flauto e orchestra (1968)
 * Sinfonia n.11 "Delle cornamuse" (1969)
 * Gabrieliana (1971)
 * Omaggio a Belmonte (1971)

Chamber music

 * Sonata for Cello and Piano (1907–1908)
 * Canto della Lontananza for Violin and Piano (1919)
 * String Quartet n.1 "Rispetti e strambotti" (1920)
 * String Quartet n.2 "Stornelli e ballate" (1923)
 * String Quartet n.3 "Cantari alla madrigalesca" (1931)
 * Epodi e giambi for Violin, oboe, viola e fagotto (1932)
 * String Quartet n.4 (1934)
 * Sonata a cinque per flauto, arpa, viola, violino e violoncello (1934)
 * String Quartet n.5 "dei capricci" (1941–1950)
 * Sonatina for Cello and Piano (1942)
 * String Quartet n.6 "l'Arca di Noé" (1947)
 * String Quartet n.7 (1950)
 * Sonata a quattro for flute, oboe, clarinet and bassoon (1954)
 * Serenata mattutina per 10 strumenti (1959)
 * Serenata per fagotto e 10 strumenti (1961)
 * Macchine per 14 strumenti (1963)
 * String Quartet n.8 "per Elisabetta" (1964)
 * Endecatode per 14 strumenti e percussione (1966)

Piano music

 * 6 morceaux (6 pezzi) (1905)
 * Bizzarrie luminose dell'alba, del meriggio, della notte (1908)
 * 3 danze antiche (1910)
 * Poemetti lunari (1909–10)
 * Tre improvvisi per Pianola
 * Impressioni (vor 1914)
 * Preludi autunnali (1914)
 * Poemi asolani (1916)
 * Barlumi (1917)
 * Maschere che passano (1918)
 * Risonanze (1918)
 * La siesta (1920)
 * A Claude Debussy (1920)
 * Omaggi: a un pappagallo, a un elefante, a un idiota (1920)
 * Cavalcate (1921)
 * Il tarlo (1922)
 * Pasqua di resurrezione (1924)
 * 3 preludi e una fuga (1926)
 * Epitaffio (1931)
 * Prélude à une fugue imaginaire (1932)
 * I minuetti di Ca'Tiepolo (1932)
 * Preludio, ritmi e canti gregoriani (1937)
 * Preludio e fuga (1940)
 * Hortus conclusus (1946)
 * Stradivario für 2 Klaviere (1955)
 * Dialogo no.2 für 2 Klaviere (1955)
 * 5 studi per domani (1959)
 * Variazione sulla pantomima dell'"Amor brujo" di Manuel de Falla (1959)
 * Bianchi e neri (1964)

Vocal works

 * Tre poesie di Angelo Poliziano (1920)
 * San Francesco d'Assisi, mistero per soli, coro e orchestra (1920–1921, New York 1922)
 * Quattro sonetti del Burchiello (1921)
 * Due sonetti del Berni (1922)
 * Le Stagioni Italiche per soprano e pianoforte (1923, Venise 1925)
 * La Cena, cantata per coro e orchestra (1927, Rochester 1929)
 * Commiato per una voce di baritono e orchestra (1934)
 * La Passione, cantata per coro e orchestra (Rome 1935)
 * De Profundis per una voce, viola e bass drum e pianoforte (Venise 1937)
 * Missa Pro Mortuis per baritono, coro e orchestra (Rome 1938)
 * Quattro Vecchie Canzoni per voce e strumenti (1940, Washington 1941)
 * Santa Eufrosina, mistero per soprano, due baritoni, coro e orchestra (Rome 1942)
 * Le Sette Allegrezze d'Amore per voce e strumenti (Milan 1945)
 * La Terra, dalle Georgiche di Virgilio (1946)
 * Mondi celesti for soprano and ten instruments (1948, Capri 1949)
 * La Festa della Sensa per baritone, chorus and orchestra (1949–1950, Brussels 1954)
 * Cinque favole (1950)
 * Preludio e morte di Macbeth for baritone and orchestra (1958, Milan 1960)
 * Sette canzonette veneziane for voice and piano (1960)

Film scores

 * Steel (1933)

title: Gian Francesco Malipiero


text:
Masyanya

Masyanya (Масяня) is a Russian adult animated web series and sitcom (later released on TV) created by Oleg Kuvaev with Macromedia Flash in 2001. The series features 8 seasons and 173 episodes as of now.

Main cast

 * Masyanya (Масяня Masânâ; real name Maria) - The title character and the eponymous heroine in her twenties who lives in an apartment in St. Petersburg. Masyanya has an oval-shaped head and always wears a miniskirt and a shirt with a bare midriff.
 * Hryundel (Хрюндель Hrûndelʼ, a derivative from Russian verb meaning "to grunt"; real name Alexander) - Masyanya's rather dense, good-natured, overall-clad boyfriend.
 * Lokhmaty (Лохматый Lohmatıĭ, Russian for "Shaggy"; real name Anton Lokhmatenko) - their friend, a pudgy and care-free drummer. Lokhmaty is later revealed to be of Ukrainian descent, his last name being Lokhmatenko.

Side Characters

 * Fyodorovna (Фёдоровна Fëdorovna) - Masyanya's mother. Given name and occupation are unknown. She is divorced.
 * Lyaska (Ляська Lâs'ka; real name Olga) - a girl from Moscow and Masyanya's friend.
 * Sanyok (Санёк Sanëk, a derivative of the full name Alexander) - homeless in a green sweater, who lives in the basement of Masyanya's house
 * Dyadya Badya (Дядя Бадя Dâdâ Badâ) - son of Masyanya and Hryundel.
 * Chuchunya (Чучуня Čučunâ) - daughter of Masyanya and Hryundel.
 * Grisha Chaynikov (Гриша Чайников Griša Čaĭnikov) - music producer.
 * Kolobukhin - bass guitar player.
 * Putin (Путин) - the president of Russia, often referred to as the czar.

Episodes
A typical Masyanya episode is only a few minutes long. Each .swf episode was typically 170-400KB in size (though sometimes up to 3MB), and consisted mainly of sarcastic (and frequently absurd) commentary on contemporary Russian life. Some of the most popular episodes include one in which Masyanya and Hryundel' snicker and later hysterically laugh while Hryundel' is recording a jingle on the radio; another involves a sexual encounter made impossible by the lack of "shtuchki" (thingies), while yet another involves the two main characters exchanging a series of increasingly awful gifts, including a horse-shaped piñata and a bag of green cats.

The episodes are generally loosely connected and the characters initially did not age. For most of the episodes, no particular sequence or storyline could be established until recently as Masyanya and Hryundel now have two kids Uncle Badya and Chuchun. They can be watched in any order, but some episodes lose a great deal of their charm if one isn't familiar with at least some of the series history.

Soundtrack
Russian pop songs are often used in the soundtracks of episodes. Several episodes are, in essence, music videos set to a particular song.

Reception
Masyanya's popularity is rapidly growing on both sides of the Atlantic. In Russia, Masyanya made the move from the Internet to television and can now be seen on several cartoons and talk shows, although its popularity is mainly supported by the Internet. In Germany, translations are being made of some of the more popular episodes. In the United States, Masyanya has become an integral feature of the Middlebury College Summer Russian Language Program in Vermont.

Censorship in Russia
At the height of the 2022 Russian invasion of Ukraine, the series broadcast episode 160 titled Vakidzasi (Вакидзаси; Wakizashi) on March 22, which was strongly critical of the war in Ukraine; the episode had featured graphic images taken from the conflict while also comparing president Vladimir Putin and his actions to that of Adolf Hitler's and stating that the only right decision Putin could make in his life would be to commit suicide. The episode ends on a happy note after Putin follows said advice in-universe. The show stayed the course with the next two episodes, 161 Kak ob'yasnit detyam (Как объяснить детям; How to explain [everything] to children) from May 13 in which Masyanya and Hryundel explain the circumstances leading to the war to their children Badya and Chuchunya, and 162 "Saint Mariuburg" (Санкт-Мариубург; Sankt-Mariuburg) from July 11 in which China invades Russia in the same manner as Russia did Ukraine in real life, and Saint Petersburg, where the episode takes place, is destroyed in the same manner as Mariupol.

In response, Russian media regulation agency Roskomnadzor, after having demanded the creators of Masyanya to pull the episode, banned the series after accusing the creators of circulating false information about the conflict. Kuvayev, who currently lives in Israel, had circumvented the take-down of the original webpage by creating a mirror site, but as of 2 April the authorities continue to threaten Kuvayev that all of his internet resources will be blocked unless he pulls the episode.

title: Masyanya


text:
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Ack, an overly excitable bot. Bots shouldn't be allowed to use exclamation marks.

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Nomination of Panicfire for deletion
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Nomination of Armoured fist for deletion
A discussion is taking place as to whether the article Armoured fist is suitable for inclusion in Wikipedia according to Wikipedia's policies and guidelines or whether it should be deleted.

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title: User talk:Weatherman667


text:
New York World Journal Tribune

The New York World Journal Tribune (WJT, and hence the nickname The Widget) was an evening daily newspaper published in New York City from September 1966 until May 1967. The World Journal Tribune represented an attempt to save the heritages of several historic New York City newspapers by merging the city's three mid-market papers (the Journal-American, the World-Telegram and Sun and the Herald Tribune) together into a consolidated newspaper.

Background
The late 1940s and the 1950s were a troubled time for newspapers throughout North America. Newspapers had acquired a new competitor for the eyes and ears of the nation, television. Competition from radio and magazines for the news audience also continued unabated. The market for evening papers in particular was affected by television and by the suburban lifestyle, but all papers were affected by it. The New York media market was by far America's largest at the time (by an even larger margin than it is currently) and had by far the most daily newspapers. Mergers had been ongoing for several years. In the 1960s the market became even more competitive, forcing the closure of the Hearst-owned New York Daily Mirror in 1963. The newspaper industry was struggling with financial troubles by the mid-1960s and had warned their unions, some of the more militant in the city at the time, that they could not survive yet another strike following devastating walk-outs in 1962–1963 and 1965.

Merger
In April 1966, in an attempt to avoid closing down, the Scripps-Howard owned New York World-Telegram and Sun merged with Hearst's New York Journal-American and the New York Herald Tribune to become the New York World Journal Tribune, an evening broadsheet newspaper which would rely on newsstand sales to survive.

The management of the merged paper told their employees that to succeed the new enterprise would need concessions from the unions, but the unions, upset that several thousand workers were planned to be laid-off, demanded their own concessions from management. The result of the impasse was a 140-day strike which delayed the debut of the new paper until September 12, 1966.

Closing
The World Journal Tribune never became economically viable, and it ceased publication eight months later, on May 5, 1967. During its short life, the paper never opened a Washington bureau, and did not have any foreign correspondents on its staff, relying instead on the Los Angeles Times–Washington Post News Service for foreign coverage.

The folding of the WJT left The New York Times, the New York Daily News, and the New York Post as the only daily English-language general circulation newspapers in New York City for many years, when in 1900 there had been fifteen.

One survivor of the demise of the World Journal Tribune was New York magazine, which began as the Sunday supplement for the Herald Tribune and continued after the merger as the supplement for the WJT. After the newspaper folded, the editor of New York, Clay Felker, bought the rights to the title with partners and brought it out as a glossy magazine.

title: New York World Journal Tribune


text:
Yahrzeit

Yahrzeit (יאָרצײַט, plural יאָרצײַטן, yortsaytn) is the anniversary of a death in Judaism. It is traditionally commemorated by reciting the Kaddish in synagogue and by lighting a long-burning candle.

Name
The word Yahrzeit is a borrowing from the Yiddish yortsayt (יאָרצײַט), ultimately from the Middle High German jārzīt. It is a doublet of the English word yeartide. Use of the word to refer to a Jewish death anniversary dates to at least the 15th century, appearing in the writings of Shalom of Neustadt, Isaac of Tyrnau, and Moses Mintz. Mordecai Jafe also uses the term in his 1612 work Levush ha-Tekehlet.

Though of Yiddish origin, many Sephardic and Mizraḥi communities adopted the word,  which likely spread through rabbinic literature. Variants of the word are found in Judeo-Arabic (yarṣayt or yarṣyat), Ladino, Judeo-Italian, Judeo-Tajik, and Judeo-Tat. Yosef Ḥayyim of Baghdad notes a once-common false etymology of the word as a Hebrew acronym. Other names for the commemoration include naḥalah (נחלה) in Hebrew, meldado and anyos in Ladino, and sāl (سال) in Judeo-Persian.

History
The tradition of commemorating a death anniversary in Judaism has ancient origins. During the Talmudic era, it was common to observe the date of a father's or teacher's death by fasting, or by abstaining from consuming meat and wine. The Gemara's discussion suggests that this was a voluntary practice in accordance with the directive to honour one's father "while alive and after his death." Rashi notes that it was customary to gather around the grave of a distinguished individual on the anniversary of his death.

The modern practice of observing Yahrzeit for parents likely originated among the Jewish communities of medieval Germany, later being adopted by Sephardic Jews.

Date of observance
Yahrzeit is typically observed on the anniversary according to the Hebrew calendar of the date of death of an immediate family member or outstanding individual. Some authorities hold that when an individual was not buried within two days of their death, the first Yahrzeit is instead held on the anniversary of their burial. There are also exceptions when the date falls on Rosh Ḥodesh or in a leap year of the Hebrew calendar:

Common practices
When commemorated by a immediate relative, the day is marked by two main practices: reciting the Mourner's Kaddish, and lighting the Yahrzeit candle, which is kept burning for twenty-four hours. Other customs including being called up to the public reading of the Torah or reciting the Haftara on the preceding Shabbat, and sponsoring a synagogue Kiddush in honour of the deceased. A lightbulb by the name of the deceased may be lit on the synagogue's Yahrzeit board. Historically, fasting was also a common practice.

According to some sources, the Yahrzeit candle holds Kabbalistic significance. Aaron Berechiah of Modena likens the burning wick in the candle to the soul in the body, citing the Proverb "man's soul is the candle of God." He notes furthermore that the numerical value of נר דלוק ('burning candle') is equivalent to that of השכינה ('the Shekhinah'). Other scholars posit that the candle-lighting tradition may have Christian origins.

Some communities, especially Sephardim in the Land of Israel, were initially opposed to reciting the Mourner's Kaddish after the first eleven months following a death, contending that it would cast a negative light on the departed. Isaac Luria offered an alternative perspective, explaining that "while the orphan's Kaddish within the eleven months helps the soul to pass from Gehinnom to Gan Eden, the Yahrzeit Kaddish elevates the soul every year to a higher sphere in paradise." Menasseh ben Israel also adopts this perspective.

Ḥasidic Jews traditionally celebrate the Yahrzeit of their respective rabbis with song, dance, and general rejoicing, resulting in a shift from the originally mournful nature of the celebration to an occasion of joyous festivity. The Mitnaggedim vehemently objected to this innovation.

Notable Yahrzeits
The most widely-observed Yahrzeit are on the Seventh of Adar I, the anniversary of Moses' death; Lag ba-Omer, the Yahrzeit of Simeon ben Yoḥai, observed at his tomb in Meron since at least the 16th century; and the Fast of Gedalia, the date of Gedaliah ben Ahikam's assassination.

A Yahrzeit celebration in honour of Meïr Ba'al ha-Nes is held in Tiberias on the 15th of Iyyar. In Morocco, annual pilgrimages are made to the tombs of Isaac ben Walid and Haïm Pinto on the anniversaries of their deaths. Until the Second World War, the Yahrzeit of Moses Isserles was observed in Cracow on the 18th of Iyyar.

In the State of Israel, the Yahrzeits of national figures are observed as holidays, such as Ben-Gurion Day, Herzl Day, Jabotinsky Day, and Rabin Day.

title: Yahrzeit