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Critical Mass (cycling)

Critical Mass is a form of direct action in which people travel as a group on bicycles at a set location and time. The idea is for people to group together to make it safe for each other to ride bicycles through their streets, based on the old adage: there's safety in numbers.

Critical Mass events highlight the numbers of people who want to use their bicycle on the streets, but are usually unable to do so without risking their safety. They are a call to action to councils, governments and road planners to properly and thoughtfully design in the safety of all road users, including those who would prefer to walk and cycle, instead of prioritising motor traffic above all else.

The event originated in 1992 in San Francisco (typically held on the last Friday of every month); by the end of 2003, the event was being held in over 300 cities around the world.

Critical Mass has been described as "monthly political-protest rides", and characterized as being part of a social movement. It has been described as a "monthly protest by cyclists reclaiming the streets." Participants have insisted that these events should be viewed as "celebrations" and spontaneous gatherings, and not as protests or organized demonstrations. This stance allows Critical Mass to argue a legal position that its events can occur without advance notification of local police. Though they are sometimes described as political, they are not necessarily.

History

Critical Mass-like bicycle tours with hundreds of participants took place in Stockholm, Sweden in the early 1970s. But the first ride within the present wave took place on Friday, September 25, 1992, at 6 pm in San Francisco. At that time, the event was known as Commute Clot and was composed of a couple of dozen cyclists who had received flyers on Market Street.

Shortly after this, some participants in that ride went to a local bicycle shop for a screening of Ted White's documentary Return of the Scorcher, about bicycle culture in the Netherlands and China in comparison with that of the United States. In that film, American human-powered vehicle and pedicab designer George Bliss noted that, in China, both motorists and bicyclists had an "understood" method of negotiating intersections without signals. Traffic would queue up at these intersections until the backlog reached a "critical mass", at which point that mass would move through the intersection. This term from the footage of the movie, was applied to the name of the ride, and the name caught on, replacing "Commute Clot" by the time of the second event.

Organization and tactics

Critical Mass has a decentralized (rather than hierarchical) structure. Critical Mass is sometimes called an "organized coincidence", with no leadership or membership. The routes of some rides are decided spontaneously by whoever is currently at the front of the ride, while others are decided prior to the ride by a popular vote of suggested routes often drawn up on photocopied fliers. The term xerocracy was coined to describe a process by which the route for a Critical Mass can be decided: anyone who has an opinion makes their own map and distributes it to the cyclists participating in the Mass. Still other rides decide the route by consensus. The disorganized nature of the event allows it to largely escape clampdown by authorities who may view the rides as forms of parades or organized protest. Additionally, the movement is free from the structural costs associated with a centralized, hierarchical organization. In order for the event to function, the only requirement is a sufficient turn-out to create a "critical mass" of riders dense enough to occupy a piece of road to the exclusion of drivers of motorized vehicles. Authorities in New York, California and Oregon have expressed concern with the difficulty of coordinating with the riders, due to the lack of leadership.

Critical Mass rides vary greatly in many respects, including frequency and number of participants. For example, many small cities have monthly Critical Mass rides with fewer than twenty riders which offer safety in numbers to cyclists in those locales, while on the opposite extreme, in what have been the largest events using the name Critical Mass, cyclists in Budapest, Hungary hold only two rides each year on April 22 (Earth Day) and September 22 (International Car Free Day). The "Budapest style" attracts tens of thousands of riders. The April 20, 2008, Budapest ride participation was estimated at 80,000 riders. In Vienna, close to Budapest, a Critical Mass Ride has been held every month since 2006 and attracts up to 1,000 or more riders.

In the Critical Mass practice of "corking", a rider breaks away from the group to block the side streets of an intersection as the mass crosses. This prevents traffic travelling through the intersection on a green signal and allows the riders to ride through red lights. This both contains cross-traffic while the mass passes and protects the mass from splitting or from drivers who might attempt to pass through the mass.

Similar organizations and movements
The Critical Mass rides have inspired a number of other bicycle movements, that range from political movements to the "Critical Tits" ride during the yearly Burning Man festival. In Chicago, a movement has grown out of the Critical Mass community to promote winter cycling via the Bikewinter campaign. The extensive news coverage of San Francisco's July 1997 ride spawned an international celebration of bicycling, called Bike Summer. Kidical Mass originated in Oregon, and encourages bicycle riding for children and families. The movement gained momentum in North America and Europe and set a record in September 2019, when 1100 riders took part in Dortmund, Germany. "Critical Sass" was an all-female version of the ride in Baton Rouge, Louisiana, that took place the second Friday of every month. The Tweed Run (along with various other vintage bike rides) is a well dressed mass which takes place annually in a number of cities across the world. Examples of Critical Mass rides for political movements includes the Free Tibet Rides (May 2008): Free Tibet Critical Mass in Columbia, Missouri, "Tibetan Freedom Bike Rally" in San Francisco (Aug 2008), and in "Bike Ride for Tibet" in London (Aug 2008).

San Jose is the home to San Jose Bike Party. Bike Party rides on the third Friday of the month with a different starting point and route each time. Rides are typically 15–25 miles in length and usually 1000-2000 riders in Summer. The ride aims to build a community of cyclists and prove that bicycles can co-exist with cars. It is different than Critical Mass in that it rides after rush hour and obeys all traffic laws and has a pre-determined route.

San Luis Obispo, California, is the home of the "Bikes are happening..." meetup. Bikes are happening... starts at Mission Plaza at 9:30 pm on the first Thursday of the month. The ride consists of a continuous half mile loop through downtown San Luis Obispo. Since there is no permit for the ride, riders are asked to follow three rules: have fun, respect the community, and obey all traffic laws.

In Portland, Oregon a tactic called a "bike swarm" has been used by Occupy Wall Street protesters to separate marching protesters from police.

A huge bicycle demonstration is the "Fahrrad-Sternfahrt" in Berlin, Germany, since 1976. Each year in June and usually have 150.000–250.000 riders. Together the 19 rides are more than 600 miles long including two sections of motorway.

Critical Manners

In San Francisco, an event known as "Critical Manners" was created as a response to Critical Mass. Critical Manners rides through the city on the second Friday of the month, with riders encouraged to obey all traffic laws such as stopping at red lights and signaling. Tucson, Arizona holds the Tuesday Night Community Bike Ride as their alternative to Critical Mass. The weekly ride encourages bicycle commuting and motor vehicle awareness in a peaceful and friendly way.

In 2007 there were conversations about starting Critical Manners in Portland, Oregon. According to the Critical Mass book, a similar project known as Courteous Mass is described as "an alternative to Critical Mass."

An alternative ride named RideCivil formed in Seattle in late 2007. Rides are on the second Friday of every month, and focus on encouraging civility between motorists, pedestrians and cyclists.

The Mobile Social is an alternative ride in Atlanta sponsored by the Atlanta Bicycle Coalition. Rides start on 2nd Thursday of every month, meeting at Woodruff Park in downtown Atlanta and a focus on promoting local small business and cycling for commuting, social and civic engagement.

On June 12, 2009, an Indianapolis Critical Manners ride called "Courteous Mass" was launched but is no longer active as of 2016.

On August 14, 2009 there was a Critical Manners ride in Vancouver, British Columbia. The ride consisted of between 70 and 100 cyclists riding through the downtown core, making all attempts to follow the rules of the road (stopping at red lights / stop signs, using hand signals to turn, using the right-most lane or bike lane when applicable). The event generated some coverage in the local media and was generally deemed a success by the participants, although there were some criticisms. The ride only survived one outing.

In Kathmandu, Nepal, it has been organised since April 2013. Cyclists gather at Kathmandu Durbar Square, Basantapur and ride round the city before grouping together again. Sometimes there are people organizing awareness programmes in this gathering. People who really love cycling and feel awareness about own health, environment they doing Critical Mass Gathering even after the heavy Nepal Earthquake 2015 with slogan "Quake or Shake, Sunny or Rainy, we have to flow with time for next smile..."

Conflicts involving Critical Mass
Critical Mass rides have generated controversy and public opposition. The group has often protested in high-profile events, ranging from major political events to the Olympics. Some critics claim that Critical Mass is a deliberate attempt to obstruct traffic and disrupt normal city functions, asserting that individuals taking part refuse to obey traffic laws.

Some bicycling advocacy groups have expressed concern that the nature of Critical Mass and altercations with motorists could weaken public support for cyclists. Though it does not condone incidents of violence and rudeness, the San Francisco Bicycle Coalition credits Critical Mass with spotlighting bicycle issues and aiding their efforts in advocating for cyclists.

title: Critical Mass (cycling)


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Photon mapping

In computer graphics, photon mapping is a two-pass global illumination rendering algorithm developed by Henrik Wann Jensen between 1995 and 2001 that approximately solves the rendering equation for integrating light radiance at a given point in space. Rays from the light source (like photons) and rays from the camera are traced independently until some termination criterion is met, then they are connected in a second step to produce a radiance value. The algorithm is used to realistically simulate the interaction of light with different types of objects (similar to other photorealistic rendering techniques). Specifically, it is capable of simulating the refraction of light through a transparent substance such as glass or water (including caustics), diffuse interreflection between illuminated objects, the subsurface scattering of light in translucent materials, and some of the effects caused by particulate matter such as smoke or water vapor. Photon mapping can also be extended to more accurate simulations of light, such as spectral rendering. Progressive photon mapping (PPM) starts with ray tracing and then adds more and more photon mapping passes to provide a progressively more accurate render.

Unlike path tracing, bidirectional path tracing, volumetric path tracing, and Metropolis light transport, photon mapping is a "biased" rendering algorithm, which means that averaging infinitely many renders of the same scene using this method does not converge to a correct solution to the rendering equation. However, it is a consistent method, and the accuracy of a render can be increased by increasing the number of photons. As the number of photons approaches infinity, a render will get closer and closer to the solution of the rendering equation.

Caustics
Light refracted or reflected causes patterns called caustics, usually visible as concentrated patches of light on nearby surfaces. For example, as light rays pass through a wine glass sitting on a table, they are refracted and patterns of light are visible on the table. Photon mapping can trace the paths of individual photons to model where these concentrated patches of light will appear.

Diffuse interreflection
Diffuse interreflection is apparent when light from one diffuse object is reflected onto another. Photon mapping is particularly adept at handling this effect because the algorithm reflects photons from one surface to another based on that surface's bidirectional reflectance distribution function (BRDF), and thus light from one object striking another is a natural result of the method. Diffuse interreflection was first modeled using radiosity solutions. Photon mapping differs though in that it separates the light transport from the nature of the geometry in the scene. Color bleed is an example of diffuse interreflection.

Subsurface scattering
Subsurface scattering is the effect evident when light enters a material and is scattered before being absorbed or reflected in a different direction. Subsurface scattering can accurately be modeled using photon mapping. This was the original way Jensen implemented it; however, the method becomes slow for highly scattering materials, and bidirectional surface scattering reflectance distribution functions (BSSRDFs) are more efficient in these situations.

Construction of the photon map (1st pass)
With photon mapping, light packets called photons are sent out into the scene from the light sources. Whenever a photon intersects with a surface, the intersection point and incoming direction are stored in a cache called the photon map. Typically, two photon maps are created for a scene: one especially for caustics and a global one for other light. After intersecting the surface, a probability for either reflecting, absorbing, or transmitting/refracting is given by the material. A Monte Carlo method called Russian roulette is used to choose one of these actions. If the photon is absorbed, no new direction is given, and tracing for that photon ends. If the photon reflects, the surface's bidirectional reflectance distribution function is used to determine the ratio of reflected radiance. Finally, if the photon is transmitting, a function for its direction is given depending upon the nature of the transmission.

Once the photon map is constructed (or during construction), it is typically arranged in a manner that is optimal for the k-nearest neighbor algorithm, as photon look-up time depends on the spatial distribution of the photons. Jensen advocates the usage of kd-trees. The photon map is then stored on disk or in memory for later usage.

Rendering (2nd pass)
In this step of the algorithm, the photon map created in the first pass is used to estimate the radiance of every pixel of the output image. For each pixel, the scene is ray traced until the closest surface of intersection is found.

At this point, the rendering equation is used to calculate the surface radiance leaving the point of intersection in the direction of the ray that struck it. To facilitate efficiency, the equation is decomposed into four separate factors: direct illumination, specular reflection, caustics, and soft indirect illumination.

For an accurate estimate of direct illumination, a ray is traced from the point of intersection to each light source. As long as a ray does not intersect another object, the light source is used to calculate the direct illumination. For an approximate estimate of indirect illumination, the photon map is used to calculate the radiance contribution.

Specular reflection can be, in most cases, calculated using ray tracing procedures (as it handles reflections well).

The contribution to the surface radiance from caustics is calculated using the caustics photon map directly. The number of photons in this map must be sufficiently large, as the map is the only source for caustics information in the scene.

For soft indirect illumination, radiance is calculated using the photon map directly. This contribution, however, does not need to be as accurate as the caustics contribution and thus uses the global photon map.

Calculating radiance using the photon map
In order to calculate surface radiance at an intersection point, one of the cached photon maps is used. The steps are:

 * 1) Gather the N nearest photons using the nearest neighbor search function on the photon map.
 * 2) Let S be the sphere that contains these N photons.
 * 3) For each photon, divide the amount of flux (real photons) that the photon represents by the area of S and multiply by the BRDF applied to that photon.
 * 4) The sum of those results for each photon represents total surface radiance returned by the surface intersection in the direction of the ray that struck it.

Optimizations

 * To avoid emitting unneeded photons, the initial direction of the outgoing photons is often constrained. Instead of simply sending out photons in random directions, they are sent in the direction of a known object that is a desired photon manipulator to either focus or diffuse the light. There are many other refinements that can be made to the algorithm: for example, choosing the number of photons to send, and where and in what pattern to send them. It would seem that emitting more photons in a specific direction would cause a higher density of photons to be stored in the photon map around the position where the photons hit, and thus measuring this density would give an inaccurate value for irradiance.  This is true; however, the algorithm used to compute radiance does not depend on irradiance estimates.
 * For soft indirect illumination, if the surface is Lambertian, then a technique known as irradiance caching may be used to interpolate values from previous calculations.
 * To avoid unnecessary collision testing in direct illumination, shadow photons can be used. During the photon mapping process, when a photon strikes a surface, in addition to the usual operations performed, a shadow photon is emitted in the same direction the original photon came from that goes all the way through the object.  The next object it collides with causes a shadow photon to be stored in the photon map.  Then during the direct illumination calculation, instead of sending out a ray from the surface to the light that tests collisions with objects, the photon map is queried for shadow photons.  If none are present, then the object has a clear line of sight to the light source and additional calculations can be avoided.
 * To optimize image quality, particularly of caustics, Jensen recommends use of a cone filter. Essentially, the filter gives weight to photons' contributions to radiance depending on how far they are from ray-surface intersections.  This can produce sharper images.
 * Image space photon mapping achieves real-time performance by computing the first and last scattering using a GPU rasterizer.

Variations

 * Although photon mapping was designed to work primarily with ray tracers, it can also be extended for use with scanline renderers.

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

title: Photon mapping


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Cayley–Dickson construction

In mathematics, the Cayley–Dickson construction, named after Arthur Cayley and Leonard Eugene Dickson, produces a sequence of algebras over the field of real numbers, each with twice the dimension of the previous one. The algebras produced by this process are known as Cayley–Dickson algebras, for example complex numbers, quaternions, and octonions. These examples are useful composition algebras frequently applied in mathematical physics.

The Cayley–Dickson construction defines a new algebra as a Cartesian product of an algebra with itself, with multiplication defined in a specific way (different from the componentwise multiplication) and an involution known as conjugation. The product of an element and its conjugate (or sometimes the square root of this product) is called the norm.

The symmetries of the real field disappear as the Cayley–Dickson construction is repeatedly applied: first losing order, then commutativity of multiplication, associativity of multiplication, and finally alternativity.

More generally, the Cayley–Dickson construction takes any algebra with involution to another algebra with involution of twice the dimension.

Hurwitz's theorem (composition algebras) states that the reals, complex numbers, quaternions, and octonions are the only (normed) division algebras (over the real numbers).

Synopsis
The Cayley–Dickson construction is due to Leonard Dickson in 1919 showing how the octonions can be constructed as a two-dimensional algebra over quaternions. In fact, starting with a field F, the construction yields a sequence of F-algebras of dimension 2n. For n = 2 it is an associative algebra called a quaternion algebra, and for n = 3 it is an alternative algebra called an octonion algebra. These instances n = 1, 2 and 3 produce composition algebras as shown below.

The case n = 1 starts with elements (a, b) in F × F and defines the conjugate (a, b)* to be (a*, –b) where a* = a in case n = 1, and subsequently determined by the formula. The essence of the F-algebra lies in the definition of the product of two  elements (a, b) and (c, d):
 * $$(a,b) \times (c,d) = (ac - d^*b, da + bc^*).$$

Proposition 1: For $$z = (a,b)$$ and $$w = (c,d),$$ the conjugate of the product is $$w^*z^* = (zw)^*.$$
 * proof: $$(c^*,-d)(a^*,-b) = (c^*a^* + b^*(-d), -bc^*-da) = (zw)^*.$$

Proposition 2: If the F-algebra is associative and $$N(z) = zz^*$$,then $$N(zw) = N(z)N(w).$$
 * proof: $$N(zw) = (ac-d^*b, da+bc^*)(c^*a^*-b^*d, -da -bc^*) = (aa^* + bb^*)(cc^* + dd^*)$$ + terms that cancel by the associative property.

Stages in construction of real algebras
Details of the construction of the classical real algebras are as follows:

Complex numbers as ordered pairs
The complex numbers can be written as ordered pairs $(a, b)$ of real numbers $a$ and $b$, with the addition operator being component-wise and with multiplication defined by

 * $$(a, b) (c, d) = (a c - b d, a d + b c).\,$$

A complex number whose second component is zero is associated with a real number: the complex number $(a, 0)$ is associated with the real number $a$.

The complex conjugate $(a, b)*$ of $(a, b)$ is given by

 * $$(a, b)^* = (a^*, -b) = (a, -b)$$

since $a$ is a real number and is its own conjugate.

The conjugate has the property that

 * $$(a, b)^* (a, b) = (a a + b b, a b - b a) = \left(a^2 + b^2, 0\right),\,$$

which is a non-negative real number. In this way, conjugation defines a norm, making the complex numbers a normed vector space over the real numbers: the norm of a complex number $z$ is

 * $$|z| = \left(z^* z\right)^\frac12.\,$$

Furthermore, for any non-zero complex number $z$, conjugation gives a multiplicative inverse,

 * $$z^{-1} = \frac{z^*}{|z|^2}.$$

As a complex number consists of two independent real numbers, they form a two-dimensional vector space over the real numbers.

Besides being of higher dimension, the complex numbers can be said to lack one algebraic property of the real numbers: a real number is its own conjugate.

Quaternions

The next step in the construction is to generalize the multiplication and conjugation operations.

Form ordered pairs $(a, b)$ of complex numbers $a$ and $b$, with multiplication defined by

 * $$(a, b) (c, d) = (a c - d^* b, d a + b c^*).\,$$

Slight variations on this formula are possible; the resulting constructions will yield structures identical up to the signs of bases.

The order of the factors seems odd now, but will be important in the next step.

Define the conjugate $(a, b)*$ of $(a, b)$ by

 * $$(a, b)^* = (a^*, -b).\,$$

These operators are direct extensions of their complex analogs: if $a$ and $b$ are taken from the real subset of complex numbers, the appearance of the conjugate in the formulas has no effect, so the operators are the same as those for the complex numbers.

The product of a nonzero element with its conjugate is a non-negative real number:

 * $$\begin{align} (a, b)^* (a, b) &= (a^*, -b) (a, b) \\ &= (a^* a + b^* b, b a^* - b a^*) \\ &= \left(|a|^2 + |b|^2, 0 \right).\, \end{align}$$

As before, the conjugate thus yields a norm and an inverse for any such ordered pair. So in the sense we explained above, these pairs constitute an algebra something like the real numbers. They are the quaternions, named by Hamilton in 1843.

As a quaternion consists of two independent complex numbers, they form a four-dimensional vector space over the real numbers.

The multiplication of quaternions is not quite like the multiplication of real numbers, though; it is not commutative – that is, if $p$ and $q$ are quaternions, it is not always true that $pq = qp$.

Octonions
All the steps to create further algebras are the same from octonions on.

This time, form ordered pairs $(p, q)$ of quaternions $p$ and $q$, with multiplication and conjugation defined exactly as for the quaternions:
 * $$(p, q) (r, s) = (p r - s^* q, s p + q r^*).\,$$

Note, however, that because the quaternions are not commutative, the order of the factors in the multiplication formula becomes important—if the last factor in the multiplication formula were $r*q$ rather than $qr*$, the formula for multiplication of an element by its conjugate would not yield a real number.

For exactly the same reasons as before, the conjugation operator yields a norm and a multiplicative inverse of any nonzero element.

This algebra was discovered by John T. Graves in 1843, and is called the octonions or the "Cayley numbers".

As an octonion consists of two independent quaternions, they form an eight-dimensional vector space over the real numbers.

The multiplication of octonions is even stranger than that of quaternions; besides being non-commutative, it is not associative – that is, if $p$, $q$, and $r$ are octonions, it is not always true that $(pq)r = p(qr)$.

For the reason of this non-associativity, octonions have no matrix representation.

Further algebras
The algebra immediately following the octonions is called the sedenions. It retains an algebraic property called power associativity, meaning that if $s$ is a sedenion, $s^{n}s^{m} = s^{n + m}$, but loses the property of being an alternative algebra and hence cannot be a composition algebra.

The Cayley–Dickson construction can be carried on ad infinitum, at each step producing a power-associative algebra whose dimension is double that of the algebra of the preceding step. All the algebras generated in this way over a field are quadratic: that is, each element satisfies a quadratic equation with coefficients from the field.

In 1954 R. D. Schafer examined the algebras generated by the Cayley–Dickson process over a field $F$ and showed they satisfy the flexible identity. He also proved that any derivation algebra of a Cayley–Dickson algebra is isomorphic to the derivation algebra of Cayley numbers, a 14-dimensional Lie algebra over $F$.

Modified Cayley–Dickson construction
The Cayley–Dickson construction, starting from the real numbers $$\mathbb R$$, generates the composition algebras $$\mathbb C$$ (the complex numbers), $$\mathbb H$$ (the quaternions), and $$\mathbb O$$ (the octonions). There are also composition algebras whose norm is an isotropic quadratic form, which are obtained through a slight modification, by replacing the minus sign in the definition of the product of ordered pairs with a plus sign, as follows: $$(a, b) (c, d) = (a c + d^* b, d a + b c^*).$$

When this modified construction is applied to $$\mathbb R$$, one obtains the split-complex numbers, which are ring-isomorphic to the direct product $$\mathbb R \times \mathbb R;$$ following that, one obtains the split-quaternions, an associative algebra isomorphic to that of the 2 × 2 real matrices; and the split-octonions, which are isomorphic to $Zorn(R)$. Applying the original Cayley–Dickson construction to the split-complexes also results in the split-quaternions and then the split-octonions.

General Cayley–Dickson construction
gave a slight generalization, defining the product and involution on $B = A ⊕ A$ for $A$ an algebra with involution (with $(xy)* = y*x*$) to be
 * $$\begin{align} (p, q) (r, s) &= (p r - \gamma s^* q, s p + q r^*)\, \\ (p, q)^* &= (p^*, -q)\, \end{align}$$

for $γ$ an additive map that commutes with $$ and left and right multiplication by any element. (Over the reals all choices of $γ$ are equivalent to −1, 0 or 1.) In this construction, $A$ is an algebra with involution, meaning: The algebra $+$ produced by the Cayley–Dickson construction is also an algebra with involution.
 * $A$ is an abelian group under $+$
 * $A$ has a product that is left and right distributive over $$
 * $A$ has an involution $(x*)* = x$, with $(x + y)* = x* + y*$, $(xy)* = y*x*$, $B = A ⊕ A$.

$B$ inherits properties from $A$ unchanged as follows. Other properties of $A$ only induce weaker properties of $B$:
 * If $A$ has an identity $1_{A}$, then $B$ has an identity $(1_{A}, 0)$.
 * If $A$ has the property that $x + x*$, $xx*$ associate and commute with all elements, then so does $B$. This property implies that any element generates a commutative associative *-algebra, so in particular the algebra is power associative.
 * If $A$ is commutative and has trivial involution, then $B$ is commutative.
 * If $A$ is commutative and associative then $B$ is associative.
 * If $A$ is associative and $x + x*$, $xx*$ associate and commute with everything, then $B$ is an alternative algebra.

title: Cayley–Dickson construction


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Jean Piccard

Jean Felix Piccard (January 28, 1884 in Basel, Switzerland – January 28, 1963 in Minneapolis, Minnesota), also known as Jean Piccard, was a Swiss-born American chemist, engineer, professor and high-altitude balloonist. He invented clustered high-altitude balloons, and with his wife Jeannette, the plastic balloon. Piccard's inventions and co-inventions are used in balloon flight, aircraft and spacecraft.

Family
Piccard and Jeannette Ridlon met at the University of Chicago where he taught and she received her master's degree. They married and had three sons, John, Paul and Donald, and also had foster children.

Stratosphere flight
Piccard was the co-pilot for his wife Jeannette on the third and final voyage of the Century of Progress. The largest balloon in the world was conceived for him to fly at the World's Fair in 1933 but was flown there by US Navy pilots who were licensed. After this flight he created the liquid oxygen converter when the liquid failed to vaporize on descent after the cabin doors were open. Piccard developed a frost-free window, that was used on this flight and later by the Navy and Air Force in the B-24 Liberator or B-26 Marauder. He used blasting caps and TNT for releasing the balloon at launch and for remote release of external ballast from inside the sealed cabin. This was the first use of pyrotechnics for remote-controlled actuating devices in aircraft, an unpopular, revolutionary idea at the time. Later his student Robert R. Gilruth, who became the director of the NASA Manned Spacecraft Center, approved and used them in spacecraft.

The July 21st, 1952 issue of The Canberra Times newspaper printed an incorrect front-page article in which Piccard claimed it would be possible for humans to fly to Mars with balloons as early as 1954, if anyone was willing to invest $250,000. Piccard had claimed he would study the light from Mars through a spectroscope to try to find evidence of oxygen and water at a high altitude to ensure his measurements were as precise as possible.

Plastic balloons

In 1935 and 1936, to reduce weight and thus enabling a balloon to reach higher altitudes, plastic balloon construction began independently by Max Cosyns in Belgium, Erich Regener in Germany, and Thomas H. Johnson and Jean Piccard, then at the Franklin Institute's Bartol Research Foundation in Swarthmore, Pennsylvania. Johnson suggested cellophane to Jean Piccard.

Piccard with his wife co-invented the plastic balloon and he designed and on 24 June 1936 flew a cellophane balloon built by his students. The balloon was unmanned, 25 ft wide, and made of tapered 33-foot (10-meter) gores and one-inch (2.54-cm) 3M Scotch transparent tape. Jean Barnhill, Harold Larson and Lloyd Schumacher cut the gores that fit together like an "orange peel." Harold Hatlestad built the radio equipment and Robert Silliman built the telemeter that sent temperature and pressure data back. Robert Hatch and Silliman maintained radio contact from a station on the roof of the university armory until the radio's battery froze from insufficient insulation. The balloon floated at 50,000 feet, and in ten hours traveled over 600 miles to near Huntsville, Arkansas.

Cluster balloons
Developed with John Akerman of the University of Minnesota and piloted by Jean Piccard in 1937 in Rochester, Minnesota, the first multi-celled balloon was called The Pleiades and was made of 98 latex rubber balloons. In a letter to Robert Gray of the Dewey and Almy Chemical Co. later published in Time magazine, Piccard describes how he broke balloons with a hunting knife and revolver to control his descent. A TNT charge released the cluster as he expected but sent burning excelsior down that destroyed the first Pleiades. He suggested to Gray that rock wool in place of excelsior would prevent similar accidents in the future.

Balloon research stopped for the most part during World War II.

In February 1946 with Otto C. Winzen, Jean Piccard proposed manned flight to the US Navy using clustered balloons made of thin plastic. In June the Office of Naval Research approved Project Helios and that year General Mills and the University of Minnesota contracted to build a cluster of 100 polyethylene balloons for atmospheric research. Helios was designed to reach 100,000 feet for ten hours with a payload of instruments.

Jean Piccard helped Winzen design the Skyhook polyethylene balloons that replaced Project Helios in 1947. Skyhook balloons were used unmanned for atmospheric research by the Navy and for manned flights by the US Air Force. Later Jean Piccard developed electronics for emptying ballast bags.

Piccard died on January 28, 1963 (his 79th birthday) in Minneapolis.

Piccard family

 * Jules Piccard (professor of chemistry)
 * Auguste Piccard (physicist, aeronaut, balloonist, hydronaut)
 * Jacques Piccard (hydronaut)
 * Bertrand Piccard (aeronaut, balloonist)
 * Jean Felix Piccard (organic chemist, aeronaut, and balloonist)
 * Jeannette Piccard (wife of Jean Felix) (aeronaut and balloonist)
 * Don Piccard (balloonist)

Legacy
In 1991, Piccard was inducted into the International Air & Space Hall of Fame at the San Diego Air & Space Museum. Gene Roddenberry named the Star Trek character Jean-Luc Picard after either Jean or his twin Auguste, and it is implied that the character is a descendant of one of the brothers. The Swiss explorer and environmentalist Bertrand Piccard claims that it was after his great-uncle Jean Piccard.

title: Jean Piccard


text:
Hypercomputation

Hypercomputation or super-Turing computation is a set of hypothetical models of computation that can provide outputs that are not Turing-computable. For example, a machine that could solve the halting problem would be a hypercomputer; so too would one that could correctly evaluate every statement in Peano arithmetic.

The Church–Turing thesis states that any "computable" function that can be computed by a mathematician with a pen and paper using a finite set of simple algorithms, can be computed by a Turing machine. Hypercomputers compute functions that a Turing machine cannot and which are, hence, not computable in the Church–Turing sense.

Technically, the output of a random Turing machine is uncomputable; however, most hypercomputing literature focuses instead on the computation of deterministic, rather than random, uncomputable functions.

History
A computational model going beyond Turing machines was introduced by Alan Turing in his 1938 PhD dissertation Systems of Logic Based on Ordinals. This paper investigated mathematical systems in which an oracle was available, which could compute a single arbitrary (non-recursive) function from naturals to naturals. He used this device to prove that even in those more powerful systems, undecidability is still present. Turing's oracle machines are mathematical abstractions, and are not physically realizable.

State space
In a sense, most functions are uncomputable: there are $\aleph_0$ computable functions, but there are an uncountable number ($$2^{\aleph_0}$$) of possible super-Turing functions.

Models
Hypercomputer models range from useful but probably unrealizable (such as Turing's original oracle machines), to less-useful random-function generators that are more plausibly "realizable" (such as a random Turing machine).

Uncomputable inputs or black-box components
A system granted knowledge of the uncomputable, oracular Chaitin's constant (a number with an infinite sequence of digits that encode the solution to the halting problem) as an input can solve a large number of useful undecidable problems; a system granted an uncomputable random-number generator as an input can create random uncomputable functions, but is generally not believed to be able to meaningfully solve "useful" uncomputable functions such as the halting problem. There are an unlimited number of different types of conceivable hypercomputers, including:

 * Turing's original oracle machines, defined by Turing in 1939.
 * A real computer (a sort of idealized analog computer) can perform hypercomputation if physics admits general real variables (not just computable reals), and these are in some way "harnessable" for useful (rather than random) computation. This might require quite bizarre laws of physics (for example, a measurable physical constant with an oracular value, such as Chaitin's constant), and would require the ability to measure the real-valued physical value to arbitrary precision, though standard physics makes such arbitrary-precision measurements theoretically infeasible.
 * Similarly, a neural net that somehow had Chaitin's constant exactly embedded in its weight function would be able to solve the halting problem, but is subject to the same physical difficulties as other models of hypercomputation based on real computation.
 * Certain fuzzy logic-based "fuzzy Turing machines" can, by definition, accidentally solve the halting problem, but only because their ability to solve the halting problem is indirectly assumed in the specification of the machine; this tends to be viewed as a "bug" in the original specification of the machines.
 * Similarly, a proposed model known as fair nondeterminism can accidentally allow the oracular computation of noncomputable functions, because some such systems, by definition, have the oracular ability to identify reject inputs that would "unfairly" cause a subsystem to run forever.
 * Dmytro Taranovsky has proposed a finitistic model of traditionally non-finitistic branches of analysis, built around a Turing machine equipped with a rapidly increasing function as its oracle. By this and more complicated models he was able to give an interpretation of second-order arithmetic. These models require an uncomputable input, such as a physical event-generating process where the interval between events grows at an uncomputably large rate.
 * Similarly, one unorthodox interpretation of a model of unbounded nondeterminism posits, by definition, that the length of time required for an "Actor" to settle is fundamentally unknowable, and therefore it cannot be proven, within the model, that it does not take an uncomputably long period of time.

"Infinite computational steps" models
In order to work correctly, certain computations by the machines below literally require infinite, rather than merely unlimited but finite, physical space and resources; in contrast, with a Turing machine, any given computation that halts will require only finite physical space and resources.

A Turing machine that can complete infinitely many steps in finite time, a feat known as a supertask. Simply being able to run for an unbounded number of steps does not suffice. One mathematical model is the Zeno machine (inspired by Zeno's paradox). The Zeno machine performs its first computation step in (say) 1 minute, the second step in ½ minute, the third step in ¼ minute, etc. By summing 1 + ½ + ¼ + ... (a geometric series) we see that the machine performs infinitely many steps in a total of 2 minutes. According to Oron Shagrir, Zeno machines introduce physical paradoxes and its state is logically undefined outside of one-side open period of [0, 2), thus undefined exactly at 2 minutes after beginning of the computation.

It seems natural that the possibility of time travel (existence of closed timelike curves (CTCs)) makes hypercomputation possible by itself. However, this is not so since a CTC does not provide (by itself) the unbounded amount of storage that an infinite computation would require. Nevertheless, there are spacetimes in which the CTC region can be used for relativistic hypercomputation. According to a 1992 paper, a computer operating in a Malament–Hogarth spacetime or in orbit around a rotating black hole could theoretically perform non-Turing computations for an observer inside the black hole. Access to a CTC may allow the rapid solution to PSPACE-complete problems, a complexity class which, while Turing-decidable, is generally considered computationally intractable.

Quantum models
Some scholars conjecture that a quantum mechanical system which somehow uses an infinite superposition of states could compute a non-computable function. This is not possible using the standard qubit-model quantum computer, because it is proven that a regular quantum computer is PSPACE-reducible (a quantum computer running in polynomial time can be simulated by a classical computer running in polynomial space).

"Eventually correct" systems
Some physically realizable systems will always eventually converge to the correct answer, but have the defect that they will often output an incorrect answer and stick with the incorrect answer for an uncomputably large period of time before eventually going back and correcting the mistake.

In mid 1960s, E Mark Gold and Hilary Putnam independently proposed models of inductive inference (the "limiting recursive functionals" and "trial-and-error predicates", respectively). These models enable some nonrecursive sets of numbers or languages (including all recursively enumerable sets of languages) to be "learned in the limit"; whereas, by definition, only recursive sets of numbers or languages could be identified by a Turing machine. While the machine will stabilize to the correct answer on any learnable set in some finite time, it can only identify it as correct if it is recursive; otherwise, the correctness is established only by running the machine forever and noting that it never revises its answer. Putnam identified this new interpretation as the class of "empirical" predicates, stating: "if we always 'posit' that the most recently generated answer is correct, we will make a finite number of mistakes, but we will eventually get the correct answer. (Note, however, that even if we have gotten to the correct answer (the end of the finite sequence) we are never sure that we have the correct answer.)" L. K. Schubert's 1974 paper "Iterated Limiting Recursion and the Program Minimization Problem" studied the effects of iterating the limiting procedure; this allows any arithmetic predicate to be computed. Schubert wrote, "Intuitively, iterated limiting identification might be regarded as higher-order inductive inference performed collectively by an ever-growing community of lower order inductive inference machines."

A symbol sequence is computable in the limit if there is a finite, possibly non-halting program on a universal Turing machine that incrementally outputs every symbol of the sequence. This includes the dyadic expansion of π and of every other computable real, but still excludes all noncomputable reals. The 'Monotone Turing machines' traditionally used in description size theory cannot edit their previous outputs; generalized Turing machines, as defined by Jürgen Schmidhuber, can. He defines the constructively describable symbol sequences as those that have a finite, non-halting program running on a generalized Turing machine, such that any output symbol eventually converges; that is, it does not change any more after some finite initial time interval. Due to limitations first exhibited by Kurt Gödel (1931), it may be impossible to predict the convergence time itself by a halting program, otherwise the halting problem could be solved. Schmidhuber uses this approach to define the set of formally describable or constructively computable universes or constructive theories of everything. Generalized Turing machines can eventually converge to a correct solution of the halting problem by evaluating a Specker sequence.

Analysis of capabilities
Many hypercomputation proposals amount to alternative ways to read an oracle or advice function embedded into an otherwise classical machine. Others allow access to some higher level of the arithmetic hierarchy. For example, supertasking Turing machines, under the usual assumptions, would be able to compute any predicate in the truth-table degree containing $$\Sigma^0_1$$ or $$\Pi^0_1$$. Limiting-recursion, by contrast, can compute any predicate or function in the corresponding Turing degree, which is known to be $$\Delta^0_2$$. Gold further showed that limiting partial recursion would allow the computation of precisely the $$\Sigma^0_2$$ predicates.

Criticism
Martin Davis, in his writings on hypercomputation, refers to this subject as "a myth" and offers counter-arguments to the physical realizability of hypercomputation. As for its theory, he argues against the claims that this is a new field founded in the 1990s. This point of view relies on the history of computability theory (degrees of unsolvability, computability over functions, real numbers and ordinals), as also mentioned above. In his argument, he makes a remark that all of hypercomputation is little more than: "if non-computable inputs are permitted, then non-computable outputs are attainable."

title: Hypercomputation


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Talk:Photon mapping

Specialisation of ray tracing?
It's hard to tell from this article what in particular makes photon mapping a specialisation of ray tracing; I assume it has something to do with the data structure used for "caching" the "photons"... ? Chas zzz brown 07:55 Jan 28, 2003 (UTC)

reverse ray tracing?
The article says that reverse ray tracing originates the light rays at the light source. But doesn't reverse ray tracing have the rays start at the camera? MichaelGensheimer 21:26, 15 Nov 2003 (UTC)

Yes you're correct ColinCren 08:10, 10 February 2007 (UTC)

Actually, quoting from Foley et al., Computer Graphics: Principles and Practice, p. 792: "It might seem that we would need only to run a conventional ray tracer "backward" from the light sources to the eye to achieve these effects. This concept has been called backward ray tracing, to indicate that it runs in the reverse direction from regular ray tracing, but it is also known as forward ray tracing to stress that it follows the actual path from the lights to the eye. We call it ray tracing from the light sources to avoid confusion!" Sampo Smolander (talk) 20:15, 25 November 2007 (UTC)

Photon energy
You write "... to decrease the energy of the photon ...". I suppose this does not refer to the engery of a photon in a physical sense. Since the energy of a photon is related to its frequency by E = hf, changing the energy will change its frequency. On the other hand, the frequency distribution of light determines its color. --Borishollas (talk) 17:23, 8 December 2007 (UTC)

Energy, in the sense of Joules, is not what is literally intended. Rather, a "photon" in photon mapping refers to a collection of light particles, and that when they strike an object, some are reflected and some are absorbed. In this sense, the "energy" (or total particles in the collection) decreases. The Monte Carlo method more accurately describes what is happening with collisions, except it treats the photons as individual light particles instead of as a group of them.

On another note, frequency does NOT necessarily determine color in real life. For example, there is no frequency of a photon for pink, rather the human eye interprets a combination of different frequencies as that color. (Similar to how yellow can be seen from yellow photons as well as from a mixture of red and green ones) Xcelerate (talk) 01:15, 18 January 2008 (UTC)

Re-did article
I organized the article, as the original one had information about various parts of the photon mapping method scattered about. I also corrected some incorrect information (including my own), that originated from the belief that radiance estimates came from photon density or irradiance estimates. I expounded on the common effects that photon mapping is used for as well. Also, I noticed that some information about different implementations of photon mapping was included before (or in replacement of) the actual method, so I moved these to the "Variations" section. I also added information about how exactly radiance was construed from a photon map, which was not present before. I hope my edits clarify and make this article seem cleaner. Comments? Xcelerate (talk) 04:49, 8 March 2008 (UTC)

bias
In the article, it is said that the bias comes from the fact that if you average infinitely many renderings, you don't get the correct solution. Although I agree with the fact itself, I am wondering why this is taken as the definition of bias, and not as "if you take an infinite number of photons" which would make more sense imho. In a statistical sense, the estimated illumination at any given pixel is not different from the expected one if you take an infinite number of photons, thus not creating any bias, ie., the expected value equal the empirical mean..over photons. Isn't it ? Nbonneel (talk) 16:46, 27 August 2009 (UTC)

What you describe is known as being "consistent". Bias is simply where a renderer produces a correct image on average, which photon mapping does not. I'm not really sure who came up with the definitions. Xcelerate (talk) 16:15, 21 July 2010 (UTC)

Russian roulette alternative
The article reads:
 * In the 1st pass of photon mapping, an alternative to using Russian roulette to determine direction is to give each photon an "energy" attribute. Each time the photon collides with an object, this attribute is also stored in the photon map. The energy is subsequently then lowered. Once the energy of the photon is below a certain pre-determined threshold, the photon stops reflecting.

Is there literature behind this idea? It doesn't seem like a good idea to me, mainly because it breaks PM's consistency -- objects which are several reflections away from a light source will be under-illuminated. Some PM implementations will insert several entries in the PM as a photon's path is traced, but they still use RR to maintain consistency. Thoughts? — xDanielx  T/C\R 09:54, 22 November 2010 (UTC)

What about wavelength?
It says in the article that the intersection point and incoming direction are stored in the photon map, but isn't the wavelength (the color) of the photon stored here too? —Kri (talk) 23:12, 15 July 2011 (UTC)

title: Talk:Photon mapping


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Factory Records

Factory Records was a Manchester-based British independent record label founded in 1978 by Tony Wilson and Alan Erasmus.

The label featured several important acts on its roster, including Joy Division, New Order, A Certain Ratio, the Durutti Column, Happy Mondays, Northside, and (briefly) Orchestral Manoeuvres in the Dark and James. Factory also ran The Haçienda nightclub, in partnership with New Order.

Factory Records used a creative team (most notably record producer Martin Hannett and graphic designer Peter Saville) which gave the label and the artists recording for it a particular sound and image. The label employed a unique cataloguing system that gave a number not just to its musical releases, but also to various other related miscellany, including artwork, films, living beings, and even Wilson's own coffin.

'The Factory'
The Factory name was first used for a club in May 1978; the first Factory night was on the 26 May 1978. The club became a Manchester legend in its own right, being known variously as the Russell Club, Caribbean Club, PSV (Public Service Vehicles) Club (so titled as it was originally a social club for bus drivers who worked from the nearby depot) and 'The Factory'. The ‘Factory’ night at The Russell Club was launched by Alan Erasmus, Tony Wilson, and helped by promoter Alan Wise. As well as attracting numerous touring bands to the area and many upcoming post punk bands, it featured local bands including the Durutti Column (managed at the time by Erasmus and Wilson), Cabaret Voltaire from Sheffield and Joy Division. The club was demolished in 2001. The club was located on the NE corner of the now demolished Hulme Crescents development, on the corner of Royce Rd and Clayburn St (53.46792°N, -2.25006°W). Peter Saville designed advertising for the club, and in September Factory released an EP of music by acts who had played at the club (the Durutti Column, Joy Division, Cabaret Voltaire and comedian John Dowie) called A Factory Sample.

1978 and 1979
As a follow-on from the successful 'Factory Nights' held at the Russell Club, Factory Records made their first release, "A Factory Sample", in January 1979. At that time there was a punk label in Manchester called Rabid Records, run by Tosh Ryan and Martin Hannett. It had several successful acts, including Slaughter & the Dogs (whose tour manager was Rob Gretton), John Cooper Clarke, and Jilted John. After his seminal TV series So It Goes, Tony Wilson was interested in the way Rabid Records ran, and was convinced that the real money and power were in album sales. With a lot of discussion, Tony Wilson, Rob Gretton and Alan Erasmus set up Factory Records, with Martin Hannett from Rabid.

In 1978, Wilson compered the new wave afternoon at Deeply Vale Festival. This was actually the fourth live appearance by the fledgling Durutti Column and that afternoon Wilson also introduced an appearance (very early in their career) by the Fall, featuring Mark E. Smith and Marc "Lard" Riley on bass guitar.

The Factory label set up an office in Erasmus' home on the first floor of 86 Palatine Road (53.42722°N, -2.23506°W), and the Factory Sample EP was released on 24 December 1978. Singles followed by A Certain Ratio (who would stay with the label) and Orchestral Manoeuvres in the Dark (who left for Virgin Records shortly afterwards). The first Factory LP, Joy Division's Unknown Pleasures, was released in June.

1980s
In January 1980, The Return of the Durutti Column was released, the first in a long series of releases by guitarist Vini Reilly. In May, Joy Division singer Ian Curtis committed suicide shortly before a planned tour of the US. The following month saw Joy Division's single "Love Will Tear Us Apart" reach the UK top twenty, and their second album Closer was released the following month. In late 1980, the remaining members of Joy Division decided to continue as New Order. Factory branched out, with Factory Benelux being run as an independent label in conjunction with Les Disques du Crepuscule, and Factory US organising distribution for the UK label's releases in America.

In 1981, Factory and New Order opened a nightclub and preparations were made to convert a Victorian textile factory near the centre of Manchester, which had lately seen service as a motor boat showroom. Hannett left the label, as he had wanted to open a recording studio instead, and subsequently sued for unpaid royalties (the case was settled out of court in 1984). Saville also quit as a partner due to problems with payments, although he continued to work for Factory. Wilson, Erasmus and Gretton formed Factory Communications Ltd.

The Haçienda (FAC 51) opened in May 1982. Although successful in terms of attendance, and attracting a lot of praise for Ben Kelly's interior design, the club lost large amounts of money in its first few years due largely to the low prices charged for entrance and at the bar, which was markedly cheaper than nearby pubs. Adjusting bar prices failed to help matters as by the mid-1980s crowds were increasingly preferring ecstasy to alcohol. Therefore the Haçienda ended up costing tens of thousands of pounds every month.

In 1983 New Order's "Blue Monday" (FAC 73) became an international chart hit. However, the label did not make any money from it since the original sleeve, die-cut and designed to look like a floppy disk, was so costly to make that the label lost 5 pence on every copy they sold. Saville noted that nobody at Factory expected Blue Monday to be a commercially successful record at all, so nobody expected the cost to be an issue.

1985 saw the first release by Happy Mondays. New Order and Happy Mondays became the most successful bands on the label, bankrolling a host of other projects. Factory, and the Haçienda, became a cultural hub of the emerging techno and acid house genres and their amalgamation with post-punk guitar music (the "Madchester" scene). 1986 saw Mick Middles' book Joy Division to New Order published by Virgin Books (later being reprinted under the title Factory). In 1989 the label extended its reach to fringe punk folk outfit To Hell With Burgundy. Factory also opened a bar (The Dry Bar, FAC 201) and a shop (The Area, FAC 281) in the Northern Quarter of Manchester.

1990s
Factory's headquarters (FAC 251) on Charles Street, near the Oxford Road BBC building, were opened in September 1990 (prior to which the company was still registered at Alan Erasmus' flat in Didsbury).

In 1991, Factory suffered two tragedies: the deaths of Martin Hannett and Dave Rowbotham. Hannett had recently re-established a relationship with the label, working with Happy Mondays, and tributes including a compilation album and a festival were organised. Rowbotham was one of the first musicians signed by the label; he was an original member of the Durutti Column and shared the guitar role with Vini Reilly; he was murdered and his body was found in his flat in Burnage. Saville's association with Factory was now reduced to simply designing for New Order and their solo projects (the band itself was in suspension, with various members recording as Electronic, Revenge and The Other Two).

By 1992, the label's two most successful bands caused the label serious financial trouble. The Happy Mondays were recording their troubled fourth album Yes Please! in Barbados, and New Order reportedly spent £400,000 on recording their comeback album Republic. London Records were interested in taking over Factory but the deal fell through when it emerged that, due to Factory's early practice of eschewing contracts, New Order rather than the label owned New Order's back catalogue.

Factory Communications Ltd, the company formed in 1981, declared bankruptcy in November 1992. Many former Factory acts, including New Order, found a new home at London Records.

The Haçienda closed in 1997 and the building was demolished shortly afterwards. It was replaced by a modern luxury apartment block in 2003, also called The Haçienda. In October 2009, Peter Hook published his book on his time as co-owner of the Haçienda, How Not to Run a Club, and in 2010 he had six bass guitars made using wood from the Haçienda's dancefloor.

2000s
The 2002 film 24 Hour Party People is centred on Factory Records, the Haçienda, and the infamous, often unsubstantiated anecdotes and stories surrounding them. Many of the people associated with Factory, including Tony Wilson, have minor parts; the central character, based on Wilson, is played by actor and comedian Steve Coogan.

Anthony Wilson, Factory Records' founder, died on 10 August 2007 at age 57, from complications arising from renal cancer.

Colin Sharp, the Durutti Column singer during 1978 who took part in the A Factory Sample EP, died on 7 September 2009, after suffering a brain haemorrhage. Although his involvement with Factory was brief, Sharp was an associate for a short while of Martin Hannett and wrote a book called Who Killed Martin Hannett, which upset Hannett's surviving relatives, who stated the book included numerous untruths and fiction. Only months after Sharp's death, Larry Cassidy, Section 25's bassist and singer, died of unknown causes, on 27 February 2010.

In early 2010, Peter Hook, in collaboration with the Haçienda's original interior designer Ben Kelly and British audio specialists Funktion-One, renovated and reopened FAC 251 (the former Factory Records headquarters on Charles Street) as a nightclub. The club still holds its original name, FAC 251, but people refer to it as "Factory". Despite Ben Kelly's design influences, Peter Hook insists, "It's not the Haçienda for fucks [sic] sake". The club has a weekly agenda, featuring DJs and live bands of various genres.

In May 2010, James Nice, owner of LTM Recordings, published the book Shadowplayers. The book charts the rise and fall of Factory and offers detailed accounts and information about many key figures involved with the label.

FAC numbers
Musical releases, and essentially anything closely associated with the label, were given a catalogue number in the form of either FAC, or FACT, followed by a number. FACT was reserved for full-length albums, while FAC was used for both single song releases and many other Factory "productions", including: posters (FAC 1 advertised a club night), The Haçienda (FAC 51), a lawsuit filed against Factory Records by Martin Hannett (FAC 61), a hairdressing salon (FAC 98), a broadcast of Channel 4's The Tube TV series (FAC 104), customised packing tape (FAC 136), a bucket on a restored watermill (FAC 148), the Haçienda cat (FAC 191), a bet between Wilson and Gretton (FAC 253), a radio advertisement (FAC 294), and a website (FAC 421). Similar numbering was used for compact disc media releases (FACD), CD Video releases (FACDV), Factory Benelux releases (FAC BN or FBN), Factory US releases (FACTUS), and Gap Records Australia releases (FACOZ), with many available numbers restricted to record releases and other directly artist-related content.

Numbers were not allocated in strict chronological order; numbers for Joy Division and New Order releases generally ended in 3, 5, or 0 (with most Joy Division and New Order albums featuring multiples of 25), A Certain Ratio and Happy Mondays in 2, and the Durutti Column in 4. Factory Classical releases were 226, 236 and so on.

Despite the demise of Factory Records in 1992, the catalogue was still active. Additions included the 24 Hour Party People film (FAC 401), its website (FAC 433) and DVD release (FACDVD 424), and a book, Factory Records: The Complete Graphic Album (FAC 461).

Even Tony Wilson's coffin received a Factory catalogue number; FAC 501.

Factory Classical
In 1989, Factory Classical was launched with five albums by composer Steve Martland, the Kreisler String Orchestra, the Duke String Quartet (which included Durutti Column viola player John Metcalfe), oboe player Robin Williams and pianist Rolf Hind. Composers included Martland, Benjamin Britten, Paul Hindemith, Francis Poulenc, Dmitri Shostakovich, Michael Tippett, György Ligeti and Elliott Carter. Releases continued until 1992, including albums by Graham Fitkin, vocal duo Red Byrd, a recording of Erik Satie's Socrate, Piers Adams playing Handel's Recorder Sonatas, Walter Hus and further recordings both of Martland's compositions and of the composer playing Mozart.

Successor labels
In 1994, Wilson attempted to revive Factory Records, in collaboration with London Records, as "Factory Too". The first release was by Factory stalwarts the Durutti Column; the other main acts on the label were Hopper and Space Monkeys, and the label gave a UK release to the first album by Stephin Merritt's side project the 6ths, Wasps' Nests. A further release ensued: a compilation EP featuring previously unsigned Manchester acts East West Coast, the Orch, Italian Love Party, and K-Track. This collection of 8 tracks (2 per band) was simply entitled A Factory Sample Too (FACD2.02). The label was active until the late 1990s, latterly independent of London Records, as was "Factory Once", which organised reissues of Factory material.

Wilson founded a short-lived fourth incarnation, F4 Records, in the early 2000s.

In 2012, Peter Saville and James Nice formed a new company called Factory Records Ltd., in association with Alan Erasmus and Oliver Wilson (son of Tony). This released only a vinyl reissue of From the Hip by Section 25. Nice subsequently revived the Factory Benelux imprint for Factory reissues, and for new recordings by Factory-associated bands. In 2019 Warner Music Group marked the 40th anniversary of Factory as a record label with a website, exhibition, and select vinyl editions including Unknown Pleasures and box set compilation Communications 1978-1992.

Factory Records recording artists
The bands with the most numerous releases on Factory Records include Joy Division/New Order, Happy Mondays, Durutti Column and A Certain Ratio. Each of these bands has between 15 and 30 FAC numbers attributed to their releases.

Retrospective
An exhibition By Colin Gibbins took place celebrating the 20th anniversary of the closing of Factory Records (1978–1992) and its musical output, Colin's collection was displayed at the Ice Plant, Manchester, between 4 and 7 May 2012. The exhibition was called FACTVM (from the Latin for 'deed accomplished').

In October 2019 a new box set was released containing both rarities and the label’s releases from its first two years.

From 19 June until 3 January 2022, Manchester's Science and Industry Museum hosted an exhibition commemorating Factory Records entitled 'Use Hearing Protection: The early years of Factory Records ' Featuring graphic designs by Peter Saville, previously unseen items from the Factory archives, and objects loaned from the estates of both Tony Wilson and Rob Gretton, the former manager of Joy Division and New Order.

title: Factory Records


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Alfred Stock

Alfred Stock (July 16, 1876 – August 12, 1946) was a German inorganic chemist. He did pioneering research on the hydrides of boron and silicon, coordination chemistry, mercury, and mercury poisoning. The German Chemical Society's Alfred-Stock Memorial Prize is named after him.

Life
Stock was born in Danzig (Gdańsk) and educated at the Friedrich-Werder grammar school in Berlin. In 1894 he began studies in chemistry at the Friedrich Wilhelm-University in Berlin. After finishing his dissertation about the quantitative separation of arsenic and antimony in the works of Emil Fischer he got his doctoral degree.

In 1899 he worked with the French chemist and toxicologist Henri Moissan in Paris for one year. He was given the task of synthesizing still unknown compounds of boron and silicon. Five years later he became professor at the University of Breslau. In 1916 he succeeded Richard Willstätter as director at the Kaiser Wilhelm Institute for Chemistry in Berlin. After a severe mercury poisoning he became the director of the Chemistry Department at the Technische Hochschule in Karlsruhe from 1926 to 1936. In 1932 he was a visiting professor at Cornell University in Ithaca, New York for four months.

A member of the NSDAP (National Socialist German Workers' Party) since 1933, Stock was anti-Semitic. From February 6, 1936, to May 7, 1938 Stock was the president of the German Chemical Society. Bombs in the Second World War damaged the house of Stock. In September 1943 he and his wife moved to Bad Warmbrunn in Silesia, but the flow of refugees forced them to move again towards west in February 1945. They found accommodation in Aken (near Dessau). After the war in 1946, Stock endeavoured to revitalize German chemistry by lectures and memoirs. He was renowned for his pioneering research on boron hydrides.

Research on the hydrides of boron and silicon
In 1909 Stock began studying the boron hydrides—the boron hydrogen chemical compounds with general formula BxHy—at Breslau. Due to their extreme reactivity and flammability in air, boron hydrides could not be purified until his development of methods for separation using high-vacuum manifolds around 1912. He performed similar work on the hydrides of silicon. The hydrides of boron and silicon represented the first family of binary compounds to approach the richness of hydrocarbons in terms of structural diversity. Not only did the boron hydrides exhibit challenging properties, their structures were also unusual. Elucidation of the structures and the associated bonding models dramatically expanded the scope of inorganic chemistry. Boron hydrides such as diborane later developed into a range of reagents for organic synthesis as well as a source of diverse ligands and building blocks for researchers. With Henri Moissan, Stock discovered silicon boride.

Research in other areas of inorganic chemistry
In 1921, Stock first prepared metallic beryllium by electrolyzing a fused mixture of sodium and beryllium fluorides. This method made beryllium available for industrial use, such as in special alloys and glasses and for making windows in X-ray tubes.

He was also influential in coordination chemistry. The term "ligand" (from ligare Latin, to bind) was first used by Stock in 1917. H. Irving and R.J.P. Williams adopted the term in a paper published in 1948. Monodentate, bidentate, tridentate characterized the number of ligands attached to a metal. Given the introduction of ligand concept, he was also able to further derive the idea of bite angle and other aspects of chelation.

The "Stock system," first published in 1919, was a system of nomenclature on binary compounds. In his own words, he considered the system to be "simple, clear, immediately intelligible, capable of the most general application." In 1924, a German commission recommended Stock system to be adopted with some accommodations. FeCl2, which would have been named iron(2)-chloride according to Stock's original idea, became iron(II) chloride in the revised proposal. In 1934 Stock agreed to the use of Roman numerals but preferred keeping the hyphen and dropping the parentheses. Although this suggestion has not been followed, the Stock system remains in use worldwide.

Interests in mercury and mercury poisoning
Stock published over 50 papers on different aspects of mercury and mercury poisoning. He also introduced sensitive tests and devised improved laboratory techniques for dealing with mercury which minimized poisoning risk, possibly initiated by his chronic mercury poisoning in 1923, due to his use of liquid mercury in some novel laboratory apparatus he invented. He became more vocal on protesting the mercury usage after realizing the toxicity of its organic derivatives. German dentists abandoned his warning in 1928 against copper amalgam usage. Nevertheless, a paper from Fleischmann, in which removal of mercury in amalgam-related illness had led to complete recovery, supported his idea. (Deutsche Medizinische Wochenschrift 1928, No. 8). A committee was founded in Berlin to investigate cases of possible mercury intoxication and hence the term micromercurialism was first used.

Retirement and death
After retirement in 1936, Stock moved from Karlsruhe to Berlin. He died in Aken, a small town near Dessau, in August 1946 at the age of 70.

Posthumous recognition
In recognition of his contributions to the field of inorganic chemistry, the German Chemical Society (Gesellschaft Deutscher Chemiker) created in 1950 the Alfred Stock Memorial Prize. The prize, consisting of a gold medal and money, is awarded every other year for "an outstanding independent scientific experimental investigation in the field of inorganic chemistry."

Publications

 * Praktikum der quantitativen anorganischen Analyse. Berlin 1909, (6. Auflage, München 1979).
 * Ultrastrukturchemie. Berlin 1920.
 * Hydrides of boron and silicon. Ithaca(USA) 1933, (Neuausgabe Ithaca(UAS) 1957).
 * Die Gefährlichkeit des Quecksilbers und der Amalgam-Zahnfüllungen. Berlin 1928.
 * Das Atom In: Angewandte Chemie Band 37, Nr. 6, 1924,, , S. 65–67.

Inventions and discoveries

 * the tension thermometer
 * the Stock high vacuum apparatus - an apparatus made of glass which allows work with highly combustible and poisonous substances to be undertaken in high vacuum.
 * the principles of the chemistry of metal-chelate complexes
 * Stock nomenclature or the Stock system - the system of naming the oxidation state of an atom in a compound

title: Alfred Stock


text:
Nullsoft

Nullsoft, Inc. was an American software house founded in Sedona, Arizona, in 1997 by programmer Justin Frankel. Its products included the Winamp media player and the SHOUTcast MP3 streaming media server.

History
In 1997, Justin Frankel, a programmer from Sedona, Arizona, founded Nullsoft, Inc in his home town. The company's name is a parody of Microsoft. Mike the Llama is the company's mascot. The company launched the media player Winamp in 1997, developed by Frankel and Dmitry Boldyrev. It was the second real-time MP3 player for Windows, following WinPlay3.

Nullsoft, along with Spinner.com, were sold to America Online (AOL) on June 1, 1999, for around $400 million and thereafter existed as a subsidiary, subsequently becoming a division of AOL Music. The headquarters were moved to San Francisco, California.

According to Bonnie Burton, then editor of the website Winamp.com, 2001 was a period of heightened tension between the Nullsoft staff and upper management, because of Frankel's uncompromising views about file-sharing. He had developed Gnutella in 2000 and released it using company infrastructure. Ars Technica also noted that AOL failed to effectively monetize or find a larger audience for Winamp. Nullsoft's San Francisco offices were closed in December 2003, with a near-concurrent departure of Frankel and the original Winamp development team. In 2013, some AOL Music sites were shut down and others sold to Townsquare Media.

In November 2013, an unofficial report surfaced that Microsoft was in talks with AOL to acquire Nullsoft. On January 14, 2014, it was officially announced that Belgian online radio aggregator Radionomy had bought Winamp and Shoutcast, formerly owned by Nullsoft. No financial details were publicly announced.

Winamp
Winamp is a media player released by Nullsoft in April 1997. By 1999, it was downloaded by 15 million people. The company released several new versions of the Winamp player and grew its monthly unique subscriber base to 60 million users by late 2004. Winamp was discontinued by Nullsoft around 2013. New versions of Winamp, which started releasing in 2023, are by a different developer named Llama Group.

SHOUTcast
SHOUTcast (currently Shoutcast) is an MP3 streaming media server.

Nullsoft Scriptable Install System
In later years, their open source installer system, the Nullsoft Scriptable Install System (NSIS) became an alternative to commercial products like InstallShield.

Other
Nullsoft's developments after acquisition included the Nullsoft Streaming Video (NSV) format, which was intended to stream media that used any audio or video codec. In 2002, the press reported a technology called Ultravox being developed by Nullsoft. The company also created the peer-to-peer networks Gnutella and WASTE. Although AOL tried to limit the distribution of Gnutella and WASTE, the Ultravox technology was reportedly used for some AOL radio services in 2003. A service called Nullsoft Television was announced in 2003 using NSV.

title: Nullsoft


text:
Passivation (chemistry)

In physical chemistry and engineering, passivation is coating a material so that it becomes "passive", that is, less readily affected or corroded by the environment. Passivation involves creation of an outer layer of shield material that is applied as a microcoating, created by chemical reaction with the base material, or allowed to build by spontaneous oxidation in the air. As a technique, passivation is the use of a light coat of a protective material, such as metal oxide, to create a shield against corrosion. Passivation of silicon is used during fabrication of microelectronic devices. Undesired passivation of electrodes, called "fouling", increases the circuit resistance so it interferes with some electrochemical applications such as electrocoagulation for wastewater treatment, amperometric chemical sensing, and electrochemical synthesis.

When exposed to air, many metals naturally form a hard, relatively inert surface layer, usually an oxide (termed the "native oxide layer") or a nitride, that serves as a passivation layer - i.e. these metals are "self-protecting". In the case of silver, the dark tarnish is a passivation layer of silver sulfide formed from reaction with environmental hydrogen sulfide. Aluminium similarly forms a stable protective oxide layer which is why it does not "rust". (In contrast, some base metals, notably iron, oxidize readily to form a rough, porous coating of rust that adheres loosely, is of higher volume than the original displaced metal, and sloughs off readily; all of which permit & promote further oxidation.) The passivation layer of oxide markedly slows further oxidation and corrosion in room-temperature air for aluminium, beryllium, chromium, zinc, titanium, and silicon (a metalloid). The inert surface layer formed by reaction with air has a thickness of about 1.5 nm for silicon, 1–10 nm for beryllium, and 1 nm initially for titanium, growing to 25 nm after several years. Similarly, for aluminium, it grows to about 5 nm after several years.

In the context of the semiconductor device fabrication, such as silicon MOSFET transistors and solar cells, surface passivation refers not only to reducing the chemical reactivity of the surface but also to eliminating the dangling bonds and other defects that form electronic surface states, which impair performance of the devices. Surface passivation of silicon usually consists of high-temperature thermal oxidation.

Mechanisms
There has been much interest in determining the mechanisms that govern the increase of thickness of the oxide layer over time. Some of the important factors are the volume of oxide relative to the volume of the parent metal, the mechanism of oxygen diffusion through the metal oxide to the parent metal, and the relative chemical potential of the oxide. Boundaries between micro grains, if the oxide layer is crystalline, form an important pathway for oxygen to reach the unoxidized metal below. For this reason, vitreous oxide coatings – which lack grain boundaries – can retard oxidation. The conditions necessary, but not sufficient, for passivation are recorded in Pourbaix diagrams. Some corrosion inhibitors help the formation of a passivation layer on the surface of the metals to which they are applied. Some compounds, dissolved in solutions (chromates, molybdates) form non-reactive and low solubility films on metal surfaces.

Discovery and etymology
The fact that iron doesn't react with concentrated nitric acid was discovered by Mikhail Lomonosov in 1738 and rediscovered by James Keir in 1790, who also noted that such pre-immersed Fe doesn't reduce silver from nitrate anymore. In the 1830s, Michael Faraday and Christian Friedrich Schönbein studied that issue systematically and demonstrated that when a piece of iron is placed in dilute nitric acid, it will dissolve and produce hydrogen, but if the iron is placed in concentrated nitric acid and then returned to the dilute nitric acid, little or no reaction will take place. In 1836, Schönbein named the first state the active condition and the second the passive condition while Faraday proposed the modern explanation of the oxide film described above (Schönbein disagreed with it), which was experimentally proven by Ulick Richardson Evans only in 1927.

Aluminium
Aluminium naturally forms a thin surface layer of aluminium oxide on contact with oxygen in the atmosphere through a process called oxidation, which creates a physical barrier to corrosion or further oxidation in many environments. Some aluminium alloys, however, do not form the oxide layer well, and thus are not protected against corrosion. There are methods to enhance the formation of the oxide layer for certain alloys. For example, prior to storing hydrogen peroxide in an aluminium container, the container can be passivated by rinsing it with a dilute solution of nitric acid and peroxide alternating with deionized water. The nitric acid and peroxide mixture oxidizes and dissolves any impurities on the inner surface of the container, and the deionized water rinses away the acid and oxidized impurities.

Generally, there are two main ways to passivate aluminium alloys (not counting plating, painting, and other barrier coatings): chromate conversion coating and anodizing. Alclading, which metallurgically bonds thin layers of pure aluminium or alloy to different base aluminium alloy, is not strictly passivation of the base alloy. However, the aluminium layer clad on is designed to spontaneously develop the oxide layer and thus protect the base alloy.

Chromate conversion coating converts the surface aluminium to an aluminium chromate coating in the range of 0.00001 - 0.00004 in in thickness. Aluminium chromate conversion coatings are amorphous in structure with a gel-like composition hydrated with water. Chromate conversion is a common way of passivating not only aluminium, but also zinc, cadmium, copper, silver, magnesium, and tin alloys.

Anodizing is an electrolytic process that forms a thicker oxide layer. The anodic coating consists of hydrated aluminium oxide and is considered resistant to corrosion and abrasion. This finish is more robust than the other processes and also provides electrical insulation, which the other two processes may not.

Carbon
In carbon quantum dot (CQD) technology, CQDs are small carbon nanoparticles (less than 10 nm in size) with some form of surface passivation.

Ferrous materials
Ferrous materials, including steel, may be somewhat protected by promoting oxidation ("rust") and then converting the oxidation to a metalophosphate by using phosphoric acid and add further protection by surface coating. As the uncoated surface is water-soluble, a preferred method is to form manganese or zinc compounds by a process commonly known as parkerizing or phosphate conversion. Older, less effective but chemically similar electrochemical conversion coatings included black oxidizing, historically known as bluing or browning. Ordinary steel forms a passivating layer in alkali environments, as reinforcing bar does in concrete.

Stainless steel
Stainless steels are corrosion-resistant, but they are not completely impervious to rusting. One common mode of corrosion in corrosion-resistant steels is when small spots on the surface begin to rust because grain boundaries or embedded bits of foreign matter (such as grinding swarf) allow water molecules to oxidize some of the iron in those spots despite the alloying chromium. This is called rouging. Some grades of stainless steel are especially resistant to rouging; parts made from them may therefore forgo any passivation step, depending on engineering decisions.

Common among all of the different specifications and types are the following steps: Prior to passivation, the object must be cleaned of any contaminants and generally must undergo a validating test to prove that the surface is 'clean.' The object is then placed in an acidic passivating bath that meets the temperature and chemical requirements of the method and type specified between customer and vendor. While nitric acid is commonly used as a passivating acid for stainless steel, citric acid is gaining in popularity as it is far less dangerous to handle, less toxic, and biodegradable, making disposal less of a challenge. Passivating temperatures can range from ambient to 60 °C, while minimum passivation times are usually 20 to 30 minutes. After passivation, the parts are neutralized using a bath of aqueous sodium hydroxide, then rinsed with clean water and dried. The passive surface is validated using humidity, elevated temperature, a rusting agent (salt spray), or some combination of the three. The passivation process removes exogenous iron, creates/restores a passive oxide layer that prevents further oxidation (rust), and cleans the parts of dirt, scale, or other welding-generated compounds (e.g. oxides).

Passivation processes are generally controlled by industry standards, the most prevalent among them today being ASTM A 967 and AMS 2700. These industry standards generally list several passivation processes that can be used, with the choice of specific method left to the customer and vendor. The "method" is either a nitric acid-based passivating bath, or a citric acid-based bath, these acids remove surface iron and rust, while sparing the chromium. The various 'types' listed under each method refer to differences in acid bath temperature and concentration. Sodium dichromate is often required as an additive to oxidise the chromium in certain 'types' of nitric-based acid baths, however this chemical is highly toxic. With citric acid, simply rinsing and drying the part and allowing the air to oxidise it, or in some cases the application of other chemicals, is used to perform the passivation of the surface.

It is not uncommon for some aerospace manufacturers to have additional guidelines and regulations when passivating their products that exceed the national standard. Often, these requirements will be cascaded down using Nadcap or some other accreditation system. Various testing methods are available to determine the passivation (or passive state) of stainless steel. The most common methods for validating the passivity of a part is some combination of high humidity and heat for a period of time, intended to induce rusting. Electro-chemical testers can also be utilized to commercially verify passivation.

Titanium
The surface of titanium and of titanium-rich alloys oxidizes immediately upon exposure to air to form a thin passivation layer of titanium oxide, mostly titanium dioxide. This layer makes it resistant to further corrosion, aside from gradual growth of the oxide layer, thickening to ~25 nm after several years in air. This protective layer makes it suitable for use even in corrosive environments such as sea water. Titanium can be anodized to produce a thicker passivation layer. As with many other metals, this layer causes thin-film interference which makes the metal surface appear colored, with the thickness of the passivation layer directly effecting the color produced.

Nickel
Nickel can be used for handling elemental fluorine, owing to the formation of a passivation layer of nickel fluoride. This fact is useful in water treatment and sewage treatment applications.

Silicon
In the area of microelectronics and photovoltaic solar cells, surface passivation is usually implemented by thermal oxidation at about 1000 °C to form a coating of silicon dioxide. Surface passivation is critical to solar cell efficiency. The effect of passivation on the efficiency of solar cells ranges from 3–7%. The surface resistivity is high, > 100 Ωcm.

Perovskite
The easiest and most widely studied method to improve perovskite solar cells is passivation. These defects usually lead to deep energy level defects in solar cells due to the presence of hanging bonds on the surface of perovskite films. Usually, small molecules or polymers are doped to interact with the hanging bonds and thus reduce the defect states. This process is similar to Tetris, i.e., we always want the layer to be full. A small molecule with the function of passivation is some kind of square that can be inserted where there is an empty space and then a complete layer is obtained. These molecules will generally have lone electron pairs or pi-electrons, so they can bind to the defective states on the surface of the cell film and thus achieve passivation of the material. Therefore, molecules such as carbonyl, nitrogen-containing molecules, and sulfur-containing molecules are considered, and recently it has been shown that π electrons can also play a role.

In addition, passivation not only improves the photoelectric conversion efficiency of perovskite cells, but also contributes to the improvement of device stability. For example, adding a passivation layer of a few nanometers thickness can effectively achieve passivation with the effect of stopping water vapor intrusion.

title: Passivation (chemistry)


text:
Talk:Yehiel De-Nur

Untitled
I think you accidentally deleted your definition of "Ka-tzetnik" which leaves the remark that people still bear the number without a reference.

I wonder if Ka-tzetnik 135633's pen name (wrote tons under that name) might not be a better title. I'm thinking of something like that done at the Mark Twain page. Just a thought.

At amazon.com, you can find books searching on "Ka-tzetnik 135633" but not by searching for "Yehiel Denur", for example.

Arthur

Oops, I just discovered another question. Amazon.com say that Eliyah Nike De-Nur is a translator on his book Shivitti: A Vision. Just thought you'd want to know.

Arthur

Karol Cetinsky
Is there any source for this name being on any of his books, other than fan publications relating to the band Joy Division? --Dhartung | Talk 01:56, 12 January 2007 (UTC)

title: Talk:Yehiel De-Nur


text:
HiDef

HiDef (short for high definition), also called 24p, is a 24 frames-per-second digital video format for high-resolution capture of motion pictures. The 24 refers to the frame rate (24 frames/second) and the p stands for progressive scanning (as opposed to interlaced scanning). As of 2003, there are two 24p HD formats: Sony 24p and Panasonic 24p.

Cameras of this capture depth have been available only since about 2001. Notably, they were used by George Lucas for the production of his second Star Wars prequel, Attack of the Clones. The advantage of shooting with digital-capture cameras is the efficiency in the production process. To edit scenes digitally, no transfer from film to digital is required. Also, if it is projected with a digital projector, no transference to film is required, either.

title: HiDef


text:
Single-8

Single-8 is a motion picture film format introduced by Fujifilm of Japan in 1965 as an alternative to the Kodak Super 8 format. The company Konan (that developed the Konan-16 subminiature camera) claims in its history page to have developed the Single-8 system in 1959.

Although never as popular internationally as Super 8, the format continued to live in parallel. As of 2023, Fuji is no longer manufacturing Single-8 film. The last 2 film stocks to cease production were Fujichrome R25N, a Daylight Balanced Filmstock, in 2012, and Fujichrome RT200N, which was Tungsten Balanced(3400K) for indoor filming, in 2010.

Details
Although the film is thinner, the other dimensions of Single-8 such as the sprocket holes and sound track are the same as Super 8. Single-8 can be projected in Super 8 projectors and vice versa. Single-8 comes pre-loaded in B-shaped cartridges, with two separate spools unlike the coaxial system of Super 8. As a result, Single-8 film offered unlimited rewind, whereas Super 8 rewind was limited to several seconds and relied on there being sufficient empty space within the cartridge for the rewound film to pile up inside.

The Single 8 cartridge was designed to use the camera's film gate to hold the film in place during exposure. This contrasted with the Kodak system which had a plastic pressure plate built into the cartridge. It was widely believed by Single 8 enthusiasts that this would offer superior film positioning, but the reality was that Super 8's plastic pressure plate could be moulded with far smaller tolerance than Single 8's metal version could be machined.

It has a polyester base that is thinner than the Kodak films, so splicing the two formats together in a finished film may require adjustment of the projector's focus at the join.

Although never as popular internationally as Super 8, the format continued to live in parallel. As of early 2007, Fuji was manufacturing two versions of Single-8 film. Fujichrome R25N was Daylight Balanced Filmstock, while Fujichrome RT200N was Tungsten Balanced(3400K) for indoor filming. The Sound Film brand is no longer made, although a magnetic sound stripe could be added to the film after processing. This option was chosen whenever sending the exposed film to Fuji in Japan. In addition to Fuji's own film, black and white film is available from Japanese company Retro Enterprises. This Single-8 black & white reversal film, named Retro X, is of ASA/ISO 200 and is manufactured in Germany.

Although Fujifilm stopped exportation of Single-8 Film to other countries, individual companies in the United States and Europe import the filmstock independently. Single-8 is readily available in its home country of Japan where even used cameras can reach high prices in online auctions on Yahoo! Japan. A used Fujica ZC1000, the top-of-the-line Single-8 camera, can fetch prices upwards to 250,000 Japanese yen (approx $2900). Daicon Film of Japan (now Gainax) produced a series of well-known tokusatsu films in the 1980s using Single-8 film, some of which are now available on DVD.

Processing Single-8 Film
Fuji's Single-8 developing process is not the same as Process EM-26, but is similar. There is more involved in the removal of the remjet antihalation backing than the now long discontinued Kodak Ektachrome Process EM-26 films. The color chemistry, while close, is slightly different, particularly the color development.

It was often recommended to send Fuji Single-8 film to Fujifilm in Japan for processing, however processing ended in 2013.

General
(Wayback Machine copy) (Wayback Machine copy)
 * American website providing Single 8 info and manuals
 * Film formats history
 * Info on "Return of Ultraman", movie shot in Single-8 with a Fujica ZC1000 camera. Japanese only.

Commercial sites offering filmstock and processing

 * Super8 Reversal Lab Netherlands, a company selling most Single-8 films and processing some stocks
 * Retro Enterprises, in Tokyo, Japan - source Single-8 (and other format) films and processing

title: Single-8