text:
Rete algorithm

The Rete algorithm (, , rarely  ,  ) is a pattern matching algorithm for implementing rule-based systems. The algorithm was developed to efficiently apply many rules or patterns to many objects, or facts, in a knowledge base. It is used to determine which of the system's rules should fire based on its data store, its facts. The Rete algorithm was designed by Charles L. Forgy of Carnegie Mellon University, first published in a working paper in 1974, and later elaborated in his 1979 Ph.D. thesis and a 1982 paper.

Overview
A naive implementation of an expert system might check each rule against known facts in a knowledge base, firing that rule if necessary, then moving on to the next rule (and looping back to the first rule when finished). For even moderate sized rules and facts knowledge-bases, this naive approach performs far too slowly. The Rete algorithm provides the basis for a more efficient implementation. A Rete-based expert system builds a network of nodes, where each node (except the root) corresponds to a pattern occurring in the left-hand-side (the condition part) of a rule. The path from the root node to a leaf node defines a complete rule left-hand-side. Each node has a memory of facts that satisfy that pattern. This structure is essentially a generalized trie. As new facts are asserted or modified, they propagate along the network, causing nodes to be annotated when that fact matches that pattern. When a fact or combination of facts causes all of the patterns for a given rule to be satisfied, a leaf node is reached and the corresponding rule is triggered.

Rete was first used as the core engine of the OPS5 production system language, which was used to build early systems including R1 for Digital Equipment Corporation. Rete has become the basis for many popular rule engines and expert system shells, including CLIPS, Jess, Drools, IBM Operational Decision Management, BizTalk Rules Engine, and Soar. The word 'Rete' is Latin for 'net' or 'comb'. The same word is used in modern Italian to mean 'network'. Charles Forgy has reportedly stated that he adopted the term 'Rete' because of its use in anatomy to describe a network of blood vessels and nerve fibers.

The Rete algorithm is designed to sacrifice memory for increased speed. In most cases, the speed increase over naïve implementations is several orders of magnitude (because Rete performance is theoretically independent of the number of rules in the system). In very large expert systems, however, the original Rete algorithm tends to run into memory and server consumption problems. Other algorithms, both novel and Rete-based, have since been designed that require less memory (e.g. Rete* or Collection Oriented Match ).

Description
The Rete algorithm provides a generalized logical description of an implementation of functionality responsible for matching data tuples ("facts") against productions ("rules") in a pattern-matching production system (a category of rule engine). A production consists of one or more conditions and a set of actions that may be undertaken for each complete set of facts that match the conditions. Conditions test fact attributes, including fact type specifiers/identifiers. The Rete algorithm exhibits the following major characteristics:

The Rete algorithm is widely used to implement matching functionality within pattern-matching engines that exploit a match-resolve-act cycle to support forward chaining and inferencing.
 * It reduces or eliminates certain types of redundancy through the use of node sharing.
 * It stores partial matches when performing joins between different fact types.  This, in turn, allows production systems to avoid complete re-evaluation of all facts each time changes are made to the production system's working memory.   Instead, the production system needs only to evaluate the changes (deltas) to working memory.
 * It allows for efficient removal of memory elements when facts are retracted from working memory.
 * It provides a means for many–many matching, an important feature when many or all possible solutions in a search network must be found.

Retes are directed acyclic graphs that represent higher-level rule sets. They are generally represented at run-time using a network of in-memory objects. These networks match rule conditions (patterns) to facts (relational data tuples). Rete networks act as a type of relational query processor, performing projections, selections and joins conditionally on arbitrary numbers of data tuples.

Productions (rules) are typically captured and defined by analysts and developers using some high-level rules language. They are collected into rule sets that are then translated, often at run time, into an executable Rete.

When facts are "asserted" to working memory, the engine creates working memory elements (WMEs) for each fact. Facts are tuples, and may therefore contain an arbitrary number of data items. Each WME may hold an entire tuple, or, alternatively, each fact may be represented by a set of WMEs where each WME contains a fixed-length tuple. In this case, tuples are typically triplets (3-tuples).

Each WME enters the Rete network at a single root node. The root node passes each WME on to its child nodes, and each WME may then be propagated through the network, possibly being stored in intermediate memories, until it arrives at a terminal node.

Alpha network
The "left" (alpha) side of the node graph forms a discrimination network responsible for selecting individual WMEs based on simple conditional tests that match WME attributes against constant values. Nodes in the discrimination network may also perform tests that compare two or more attributes of the same WME. If a WME is successfully matched against the conditions represented by one node, it is passed to the next node. In most engines, the immediate child nodes of the root node are used to test the entity identifier or fact type of each WME. Hence, all the WMEs that represent the same entity type typically traverse a given branch of nodes in the discrimination network.

Within the discrimination network, each branch of alpha nodes (also called 1-input nodes) terminates at a memory, called an alpha memory. These memories store collections of WMEs that match each condition in each node in a given node branch. WMEs that fail to match at least one condition in a branch are not materialised within the corresponding alpha memory. Alpha node branches may fork in order to minimise condition redundancy.

Beta network
The "right" (beta) side of the graph chiefly performs joins between different WMEs. It is optional, and is only included if required. It consists of 2-input nodes where each node has a "left" and a "right" input. Each beta node sends its output to a beta memory.

In descriptions of Rete, it is common to refer to token passing within the beta network. In this article, however, we will describe data propagation in terms of WME lists, rather than tokens, in recognition of different implementation options and the underlying purpose and use of tokens. As any one WME list passes through the beta network, new WMEs may be added to it, and the list may be stored in beta memories. A WME list in a beta memory represents a partial match for the conditions in a given production.

WME lists that reach the end of a branch of beta nodes represent a complete match for a single production, and are passed to terminal nodes. These nodes are sometimes called p-nodes, where "p" stands for production. Each terminal node represents a single production, and each WME list that arrives at a terminal node represents a complete set of matching WMEs for the conditions in that production. For each WME list it receives, a production node will "activate" a new production instance on the "agenda". Agendas are typically implemented as prioritised queues.

Beta nodes typically perform joins between WME lists stored in beta memories and individual WMEs stored in alpha memories. Each beta node is associated with two input memories. An alpha memory holds WM and performs "right" activations on the beta node each time it stores a new WME. A beta memory holds WME lists and performs "left" activations on the beta node each time it stores a new WME list. When a join node is right-activated, it compares one or more attributes of the newly stored WME from its input alpha memory against given attributes of specific WMEs in each WME list contained in the input beta memory. When a join node is left-activated it traverses a single newly stored WME list in the beta memory, retrieving specific attribute values of given WMEs. It compares these values with attribute values of each WME in the alpha memory.

Each beta node outputs WME lists that are either stored in a beta memory or sent directly to a terminal node. WME lists are stored in beta memories whenever the engine will perform additional left activations on subsequent beta nodes.

Logically, a beta node at the head of a branch of beta nodes is a special case because it takes no input from any beta memory higher in the network. Different engines handle this issue in different ways. Some engines use specialised adapter nodes to connect alpha memories to the left input of beta nodes. Other engines allow beta nodes to take input directly from two alpha memories, treating one as a "left" input and the other as a "right" input. In both cases, "head" beta nodes take their input from two alpha memories.

In order to eliminate node redundancies, any one alpha or beta memory may be used to perform activations on multiple beta nodes. As well as join nodes, the beta network may contain additional node types, some of which are described below. If a Rete contains no beta network, alpha nodes feed tokens, each containing a single WME, directly to p-nodes. In this case, there may be no need to store WMEs in alpha memories.

Conflict resolution
During any one match-resolve-act cycle, the engine will find all possible matches for the facts currently asserted to working memory. Once all the current matches have been found, and corresponding production instances have been activated on the agenda, the engine determines an order in which the production instances may be "fired". This is termed conflict resolution, and the list of activated production instances is termed the conflict set. The order may be based on rule priority (salience), rule order, the time at which facts contained in each instance were asserted to the working memory, the complexity of each production, or some other criteria. Many engines allow rule developers to select between different conflict resolution strategies or to chain a selection of multiple strategies.

Conflict resolution is not defined as part of the Rete algorithm, but is used alongside the algorithm. Some specialised production systems do not perform conflict resolution.

Production execution
Having performed conflict resolution, the engine now "fires" the first production instance, executing a list of actions associated with the production. The actions act on the data represented by the production instance's WME list.

By default, the engine will continue to fire each production instance in order until all production instances have been fired. Each production instance will fire only once, at most, during any one match-resolve-act cycle. This characteristic is termed refraction. However, the sequence of production instance firings may be interrupted at any stage by performing changes to the working memory. Rule actions can contain instructions to assert or retract WMEs from the working memory of the engine. Each time any single production instance performs one or more such changes, the engine immediately enters a new match-resolve-act cycle. This includes "updates" to WMEs currently in the working memory. Updates are represented by retracting and then re-asserting the WME. The engine undertakes matching of the changed data which, in turn, may result in changes to the list of production instances on the agenda. Hence, after the actions for any one specific production instance have been executed, previously activated instances may have been de-activated and removed from the agenda, and new instances may have been activated.

As part of the new match-resolve-act cycle, the engine performs conflict resolution on the agenda and then executes the current first instance. The engine continues to fire production instances, and to enter new match-resolve-act cycles, until no further production instances exist on the agenda. At this point the rule engine is deemed to have completed its work, and halts.

Some engines support advanced refraction strategies in which certain production instances executed in a previous cycle are not re-executed in the new cycle, even though they may still exist on the agenda.

It is possible for the engine to enter into never-ending loops in which the agenda never reaches the empty state. For this reason, most engines support explicit "halt" verbs that can be invoked from production action lists. They may also provide automatic loop detection in which never-ending loops are automatically halted after a given number of iterations. Some engines support a model in which, instead of halting when the agenda is empty, the engine enters a wait state until new facts are asserted externally.

As for conflict resolution, the firing of activated production instances is not a feature of the Rete algorithm. However, it is a central feature of engines that use Rete networks. Some of the optimisations offered by Rete networks are only useful in scenarios where the engine performs multiple match-resolve-act cycles.

Existential and universal quantifications
Conditional tests are most commonly used to perform selections and joins on individual tuples. However, by implementing additional beta node types, it is possible for Rete networks to perform quantifications. Existential quantification involves testing for the existence of at least one set of matching WMEs in working memory. Universal quantification involves testing that an entire set of WMEs in working memory meets a given condition. A variation of universal quantification might test that a given number of WMEs, drawn from a set of WMEs, meets given criteria. This might be in terms of testing for either an exact number or a minimum number of matches.

Quantification is not universally implemented in Rete engines, and, where it is supported, several variations exist. A variant of existential quantification referred to as negation is widely, though not universally, supported, and is described in seminal documents. Existentially negated conditions and conjunctions involve the use of specialised beta nodes that test for non-existence of matching WMEs or sets of WMEs. These nodes propagate WME lists only when no match is found. The exact implementation of negation varies. In one approach, the node maintains a simple count on each WME list it receives from its left input. The count specifies the number of matches found with WMEs received from the right input. The node only propagates WME lists whose count is zero. In another approach, the node maintains an additional memory on each WME list received from the left input. These memories are a form of beta memory, and store WME lists for each match with WMEs received on the right input. If a WME list does not have any WME lists in its memory, it is propagated down the network. In this approach, negation nodes generally activate further beta nodes directly, rather than storing their output in an additional beta memory. Negation nodes provide a form of 'negation as failure'.

When changes are made to working memory, a WME list that previously matched no WMEs may now match newly asserted WMEs. In this case, the propagated WME list and all its extended copies need to be retracted from beta memories further down the network. The second approach described above is often used to support efficient mechanisms for removal of WME lists. When WME lists are removed, any corresponding production instances are de-activated and removed from the agenda.

Existential quantification can be performed by combining two negation beta nodes. This represents the semantics of double negation (e.g., "If NOT NOT any matching WMEs, then..."). This is a common approach taken by several production systems.

Memory indexing
The Rete algorithm does not mandate any specific approach to indexing the working memory. However, most modern production systems provide indexing mechanisms. In some cases, only beta memories are indexed, whilst in others, indexing is used for both alpha and beta memories. A good indexing strategy is a major factor in deciding the overall performance of a production system, especially when executing rule sets that result in highly combinatorial pattern matching (i.e., intensive use of beta join nodes), or, for some engines, when executing rules sets that perform a significant number of WME retractions during multiple match-resolve-act cycles. Memories are often implemented using combinations of hash tables, and hash values are used to perform conditional joins on subsets of WME lists and WMEs, rather than on the entire contents of memories. This, in turn, often significantly reduces the number of evaluations performed by the Rete network.

Removal of WMEs and WME lists
When a WME is retracted from working memory, it must be removed from every alpha memory in which it is stored. In addition, WME lists that contain the WME must be removed from beta memories, and activated production instances for these WME lists must be de-activated and removed from the agenda. Several implementation variations exist, including tree-based and rematch-based removal. Memory indexing may be used in some cases to optimise removal.

Handling ORed conditions
When defining productions in a rule set, it is common to allow conditions to be grouped using an OR connective. In many production systems, this is handled by interpreting a single production containing multiple ORed patterns as the equivalent of multiple productions. The resulting Rete network contains sets of terminal nodes which, together, represent single productions. This approach disallows any form of short-circuiting of the ORed conditions. It can also, in some cases, lead to duplicate production instances being activated on the agenda where the same set of WMEs match multiple internal productions. Some engines provide agenda de-duplication in order to handle this issue.

Diagram
The following diagram illustrates the basic Rete topography, and shows the associations between different node types and memories.

 * Most implementations use type nodes to perform the first level of selection on tuple working memory elements.  Type nodes can be considered as specialized select nodes.   They discriminate between different tuple relation types.
 * The diagram does not illustrate the use of specialized nodes types such as negated conjunction nodes.  Some engines implement several different node specialisations in order to extend functionality and maximise optimisation.
 * The diagram provides a logical view of the Rete.  Implementations may differ in physical detail.   In particular, the diagram shows dummy inputs providing right activations at the head of beta node branches.  Engines may implement other approaches, such as adapters that allow alpha memories to perform right activations directly.
 * The diagram does not illustrate all node-sharing possibilities.

For a more detailed and complete description of the Rete algorithm, see chapter 2 of Production Matching for Large Learning Systems by Robert Doorenbos (see link below).

Alpha Network
A possible variation is to introduce additional memories for each intermediate node in the discrimination network. This increases the overhead of the Rete, but may have advantages in situations where rules are dynamically added to or removed from the Rete, making it easier to vary the topology of the discrimination network dynamically.

An alternative implementation is described by Doorenbos. In this case, the discrimination network is replaced by a set of memories and an index. The index may be implemented using a hash table. Each memory holds WMEs that match a single conditional pattern, and the index is used to reference memories by their pattern. This approach is only practical when WMEs represent fixed-length tuples, and the length of each tuple is short (e.g., 3-tuples). In addition, the approach only applies to conditional patterns that perform equality tests against constant values. When a WME enters the Rete, the index is used to locate a set of memories whose conditional pattern matches the WME attributes, and the WME is then added directly to each of these memories. In itself, this implementation contains no 1-input nodes. However, in order to implement non-equality tests, the Rete may contain additional 1-input node networks through which WMEs are passed before being placed in a memory. Alternatively, non-equality tests may be performed in the beta network described below.

Beta Network
A common variation is to build linked lists of tokens where each token holds a single WME. In this case, lists of WMEs for a partial match are represented by the linked list of tokens. This approach may be better because it eliminates the need to copy lists of WMEs from one token to another. Instead, a beta node needs only to create a new token to hold a WME it wishes to join to the partial match list, and then link the new token to a parent token stored in the input beta memory. The new token now forms the head of the token list, and is stored in the output beta memory.

Beta nodes process tokens. A token is a unit of storage within a memory and also a unit of exchange between memories and nodes. In many implementations, tokens are introduced within alpha memories where they are used to hold single WMEs. These tokens are then passed to the beta network.

Each beta node performs its work and, as a result, may create new tokens to hold a list of WMEs representing a partial match. These extended tokens are then stored in beta memories, and passed to subsequent beta nodes. In this case, the beta nodes typically pass lists of WMEs through the beta network by copying existing WME lists from each received token into new tokens and then adding further WMEs to the lists as a result of performing a join or some other action. The new tokens are then stored in the output memory.

Miscellaneous considerations
Although not defined by the Rete algorithm, some engines provide extended functionality to support greater control of truth maintenance. For example, when a match is found for one production, this may result in the assertion of new WMEs which, in turn, match the conditions for another production. If a subsequent change to working memory causes the first match to become invalid, it may be that this implies that the second match is also invalid. The Rete algorithm does not define any mechanism to define and handle these logical truth dependencies automatically. Some engines, however, support additional functionality in which truth dependencies can be automatically maintained. In this case, the retraction of one WME may lead to the automatic retraction of additional WMEs in order to maintain logical truth assertions.

The Rete algorithm does not define any approach to justification. Justification refers to mechanisms commonly required in expert and decision systems in which, at its simplest, the system reports each of the inner decisions used to reach some final conclusion. For example, an expert system might justify a conclusion that an animal is an elephant by reporting that it is large, grey, has big ears, a trunk and tusks. Some engines provide built-in justification systems in conjunction with their implementation of the Rete algorithm.

This article does not provide an exhaustive description of every possible variation or extension of the Rete algorithm. Other considerations and innovations exist. For example, engines may provide specialised support within the Rete network in order to apply pattern-matching rule processing to specific data types and sources such as programmatic objects, XML data or relational data tables. Another example concerns additional time-stamping facilities provided by many engines for each WME entering a Rete network, and the use of these time-stamps in conjunction with conflict resolution strategies. Engines exhibit significant variation in the way they allow programmatic access to the engine and its working memory, and may extend the basic Rete model to support forms of parallel and distributed processing.

Optimization and performance
Several optimizations for Rete have been identified and described in academic literature. Several of these, however, apply only in very specific scenarios, and therefore often have little or no application in a general-purpose rules engine. In addition, alternative algorithms such as TREAT, developed by Daniel P. Miranker LEAPS, and Design Time Inferencing (DeTI) have been formulated that may provide additional performance improvements.

The Rete algorithm is suited to scenarios where forward chaining and "inferencing" is used to calculate new facts from existing facts, or to filter and discard facts in order to arrive at some conclusion. It is also exploited as a reasonably efficient mechanism for performing highly combinatorial evaluations of facts where large numbers of joins must be performed between fact tuples. Other approaches to performing rule evaluation, such as the use of decision trees, or the implementation of sequential engines, may be more appropriate for simple scenarios, and should be considered as possible alternatives.

Performance of Rete is also largely a matter of implementation choices (independent of the network topology), one of which (the use of hash tables) leads to major improvements. Most of the performance benchmarks and comparisons available on the web are biased in some way or another. To mention only a frequent bias and an unfair type of comparison: 1) the use of toy problems such as the Manners and Waltz examples; such examples are useful to estimate specific properties of the implementation, but they may not reflect real performance on complex applications; 2) the use of an old implementation; for instance, the references in the following two sections (Rete II and Rete-NT) compare some commercial products to totally outdated versions of CLIPS and they claim that the commercial products may be orders of magnitude faster than CLIPS; this is forgetting that CLIPS 6.30 (with the introduction of hash tables as in Rete II) is orders of magnitude faster than the version used for the comparisons (CLIPS 6.04).

Rete II
In the 1980s, Charles Forgy developed a successor to the Rete algorithm named Rete II. Unlike the original Rete (which is public domain) this algorithm was not disclosed. Rete II claims better performance for more complex problems (even orders of magnitude ), and is officially implemented in CLIPS/R2, a C/++ implementation and in OPSJ, a Java implementation in 1998. Rete II gives about a 100 to 1 order of magnitude performance improvement in more complex problems as shown by KnowledgeBased Systems Corporation benchmarks.

Rete II can be characterized by two areas of improvement; specific optimizations relating to the general performance of the Rete network (including the use of hashed memories in order to increase performance with larger sets of data), and the inclusion of a backward chaining algorithm tailored to run on top of the Rete network. Backward chaining alone can account for the most extreme changes in benchmarks relating to Rete vs. Rete II. Rete II is implemented in the commercial product Advisor from FICO, formerly called Fair Isaac

Jess (at least versions 5.0 and later) also adds a commercial backward chaining algorithm on top of the Rete network, but it cannot be said to fully implement Rete II, in part due to the fact that no full specification is publicly available.

Rete-III
In the early 2000s, the Rete III engine was developed by Charles Forgy in cooperation with FICO engineers. The Rete III algorithm, which is not Rete-NT, is the FICO trademark for Rete II and is implemented as part of the FICO Advisor engine. It is basically the Rete II engine with an API that allows access to the Advisor engine because the Advisor engine can access other FICO products.

Rete-NT
In 2010, Forgy developed a new generation of the Rete algorithm. In an InfoWorld benchmark, the algorithm was deemed 500 times faster than the original Rete algorithm and 10 times faster than its predecessor, Rete II. This algorithm is now licensed to Sparkling Logic, the company that Forgy joined as investor and strategic advisor, as the inference engine of the SMARTS product.

Rete-OO
Considering that Rete aims to support first-order logic (basically if-then-else statements), Rete-OO aims to provide a rule-based system that supports uncertainty (where the information to make a decision is missing or is inaccurate). According to the author's proposal, the rule "if Danger then Alarm" would be improved to something such as "given the probability of Danger, there will be a certain probability of hearing an Alarm" or even "the greater the Danger, the louder should be Alarm". For this it extends the Drools language (which already implements the Rete algorithm) to make it support probabilistic logic, like fuzzy logic and Bayesian networks.

title: Rete algorithm


text:
William Emerson (mathematician)

William Emerson (14 May 1701 – 20 May 1782) was an English mathematician. He was born in Hurworth, near Darlington, where his father, Dudley Emerson, also a mathematician, taught a school.

Biography
William himself had a small estate in Weardale called Castle Gate situated not far from Eastgate where he would repair to work throughout the summer on projects as disparate as stonemasonry and watchmaking. Unsuccessful as a teacher, he devoted himself entirely to studious retirement. Possessed of remarkable energy and forthrightness of speech, Emerson published many works which are singularly free from errata.

In The Principles of Mechanics (1754) he shows a wind-powered vehicle in which the vertically mounted propeller gives direct power to the front wheels via a system of cogs. In mechanics he never advanced a proposition which he had not previously tested in practice, nor published an invention without first proving its effects by a model. He was skilled in the science of music, the theory of sounds, and the ancient and modern scales; but he never attained any excellence as a performer. He died on 20 May 1782 at his native village, where his gravestone bears epitaphs in Latin and Hebrew.

Emerson dressed in old clothes and his manners were uncouth. He wore his shirt back to front and his legs wrapped in sacking so as not to scorch them as he sat over the fire. He declined an offer to become FRS because it would cost too much after all the expense of farthing candles he had been put to in the course of his life of study. Emerson rode regularly into Darlington on a horse like Don Quixote's, led by a hired small boy. In old age, plagued by the stone, he would alternately pray and curse, wishing his soul 'could shake off the rags of mortality without such a clitter-me-clatter.'

Like his fellow County Durham savant John Bird, Emerson makes an appearance in Mason and Dixon by Thomas Pynchon.

Works

Emerson's works include:

It is notable to remark that in "The Doctrine of Proportionality" Emerson was first to introduce ∝ as the symbol for proportionality.
 * The Doctrine of Fluxions (1748); 3rd edition (1768)
 * The Projection of the Sphere, Orthographic, Stereographic and Gnomical (1749)
 * The Elements of Trigonometry (1749); 3rd edition (1788)
 * The Principles of Mechanics (1754); 3rd edition (1773)
 * A Treatise of Navigation (1755)
 * A Treatise of Algebra, in two books (1764)
 * The Arithmetic of Infinites, and the Differential Method, illustrated by Examples (1767)
 * Mechanics, or the Doctrine of Motion (1769)
 * The Elements of Optics, in four books (1768)
 * A System of Astronomy (1769)
 * The Laws of Centripetal and Centrifugal Force (1769)
 * The Mathematical Principles of Geography (1770)
 * Tracts (1770)
 * Cyclomathesis, or an Easy Introduction to the several branches of the Mathematics (1770), in ten volumes
 * A Short Comment on Sir Isaac Newton's Principia; to which is added, A Defence of Sir Isaac against the objections that have been made to several parts of his works (1770)
 * A Miscellaneous Treatise containing several Mathematical Subjects (1776).

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

title: William Emerson (mathematician)


text:
The Daily Californian

The Daily Californian (Daily Cal) is an independent, student-run newspaper that serves the University of California, Berkeley, campus and its surrounding community. It formerly published a print edition four days a week on Monday, Tuesday, Thursday, and Friday during the academic year, and twice a week during the summer. Since the beginning of the COVID-19 pandemic in California, however, The Daily Californian has been publishing a print newspaper once a week on Thursdays.

20th century
The Daily Californian became independent from UC Berkeley in 1971 after the campus administration fired three senior editors over an editorial that encouraged readers to "take back" People's Park. Both sides came to an agreement, and The Daily Californian gained financial and editorial independence from the university and is now published by an independent corporation called the Independent Berkeley Students Publishing Company, Inc. The paper licenses its name from the Regents of the University of California.

On November 24, 1982, three days after the November 20th Big Game (now known for The Play), early morning readers of the Daily Cal were chagrined to find in the headline of the front page: "NCAA Awards Big Game to Stanford." Hundreds of copies of the Daily Cal with this fake headline had been strewn about campus in the wee hours. This was in fact a hoax perpetrated by aggrieved Stanford fans.

The Daily Californian has a history of publishing spirited editorials, and in some cases, editions containing controversial editorials have been subjected to newspaper theft. In 2002, Berkeley Mayor Tom Bates agreed to pay restitution after admitting to having thrown away a thousand copies of The Daily Californian after it endorsed his opponent, then-Mayor Shirley Dean. In May 2003, nearly 5,000 papers were stolen by students protesting coverage of the arrest of a Cal football player. The largest act of theft took place in November 1996 when the paper's senior editorial board endorsed Proposition 209. Nearly 23,000 papers were stolen on Election Day 1996, and in the following days, copies of the paper were tossed off the balcony of the newspaper's office and burned in effigy.

As a way to repair relations with campus community members angered by the publication of the editorial endorsing Proposition 209, editors at the Daily Cal established the nation's first regular college newspaper sex column. The column, now known colloquially as "Sex on Tuesday", led to college papers across the country to create similar sex columns.

21st century
On October 16, 2006, the Daily Cal launched its first blog, The Daily Clog, a student-life blog that accumulates various tidbits about Berkeley and college life.

On August 25, 2008, the Daily Cal announced that it would no longer print a paper version of the newspaper on Wednesdays amidst a decline in advertising revenues and higher newspaper costs.

The Daily Californian Alumni Association
Many former Daily Cal staffers have joined The Daily Californian Alumni Association (DCAA) since its resurrection in August 1996. A unit of The Daily Californian Education Foundation, the DCAA provides mentorship and financial support to the current student staff.

Membership is open to all former staff members of The Daily Californian or student publications office staff (pre 1971). Reunions are held every October during homecoming weekend on the Berkeley campus.

Notable alumni

 * Adam Rapoport (1992), former editor-in-chief, Bon Appétit
 * Max Boot (1992), conservative columnist and author
 * Darrin Bell (1993), Pulitzer Prize-winning editorial cartoonist, Washington Post Writers Group and King Features
 * David Brock (1983), founder, Media Matters for America
 * Warrington Colescott (1941–42), painter and printmaker
 * John R. Emshwiller (1972), senior national correspondent, The Wall Street Journal
 * Ron Fimrite (1949), humorist, historian, author, and sportswriter, Sports Illustrated
 * Marguerite Higgins (1941), Pulitzer Prize-winning war correspondent
 * Karl Kasten (1938), abstract expressionist artist
 * David Lazarus (1983), business and consumer columnist, Los Angeles Times and San Francisco Chronicle
 * T. Christian Miller (1992), Pulitzer Prize-winning investigative reporter, author, and war correspondent, ProPublica
 * Johnathan A. Rodgers (1967), CEO and president, TV One, former president, Discovery Networks, and reporter, Sports Illustrated and Newsweek
 * Michael Silver (1988), columnist, NFL.com and Sports Illustrated, where he authored the magazine's Super Bowl game story for 12 straight years from 1994 through 2006, and co-author of books by Jerry Rice, Dennis Rodman, Kurt Warner, and Natalie Coughlin
 * Henry T. Weinstein (1966), reporter, Los Angeles Times
 * Jann Wenner (1966), founder, Rolling Stone magazine

title: The Daily Californian


text:
Kangaroo Jack

Kangaroo Jack is a 2003 buddy comedy film directed by David McNally from a screenplay by Steve Bing and Scott Rosenberg with a story by Bing and Barry O'Brien. It is also produced by Jerry Bruckheimer with music by Trevor Rabin. The film tells the story of two childhood friends who get caught up with the mob and are forced to deliver $50,000 to Australia, but things go haywire when the money is lost to a wild kangaroo. It stars Jerry O'Connell, Anthony Anderson, Estella Warren, Michael Shannon and Christopher Walken, with Adam Garcia as the uncredited voice of the titular character.

Kangaroo Jack was released in the United States on January 17, 2003, by Warner Bros. Pictures. The film was strongly panned by critics, who criticized the screenplay, and in its false advertising as a family film, its humor, violence, and innuendoes, although the visuals and soundtrack were praised. It grossed $88.1 million worldwide on a $60 million budget.

An animated sequel titled Kangaroo Jack: G'Day U.S.A.! was produced and released direct-to-video in 2004.

Plot
In 1982 Brooklyn, a boy named Charlie Carbone is about to become the stepson of crime boss Salvatore "Sal" Maggio. The mobster's apprentice Frankie Lombardo tries to drown Charlie, but a boy named Louis Booker saves him, and they become best friends.

Twenty years later, Charlie operates a beauty salon set up by Sal, whose henchmen take 80% of the profits, barely leaving Charlie enough money for maintenance. After they botch hiding some stolen TVs, Sal gives Charlie and Louis one more chance. Under instructions from Frankie, they are to deliver a package to a man named Mr. Smith in Coober Pedy, Australia. Frankie also warns them against opening the package, and provides them with Mr. Smith's number. Unknown to the duo, Sal has cancelled their return trip. Louis opens the package on the plane and finds $50,000 cash.

Arriving in Australia, Charlie and Louis drive to Coober Pedy. Along their way, they accidentally run over a red kangaroo. Louis thinks it is dead and puts his jacket and sunglasses on the kangaroo, posing for photographs as a joke. The kangaroo suddenly regains consciousness, kicks Charlie, and hops away with the $50,000 in the jacket. Charlie and Louis give chase but crash their rental car, and the kangaroo escapes.

At a pub in Alice Springs, Louis calls Mr. Smith, who thinks he and Charlie stole his package and threatens to kill them. Back in New York, Sal gets a call from Mr. Smith complaining that Charlie and Louis haven't arrived, then sends Frankie and some henchmen to Australia to investigate. Meanwhile, Charlie and Louis attempt to reclaim the money from the kangaroo by shooting it with a tranquilizer in a plane. The attempt fails when Louis accidentally shoots Blue, the pilot, and strands the duo in the desert. They spend hours wandering in the desert, during which Charlie hallucinates finding a jeep, and they soon meet Jessie, an American woman from the Outback Wildlife Foundation. After being knocked out by Jessie, Charlie has a nightmare with a speaking version of the kangaroo, plus two other kangaroos possessing Sal and Louis's voices, who taunt him by calling him "Chicken Blood" repeatedly.

The following day, the three track the kangaroo to the Todd River, attempting to catch it with bolas, but Louis accidentally botches their attempt when ants crawl up his pants. While waiting for the next opportunity to catch the kangaroo, Charlie begins developing feelings for Jessie. Mr. Smith and his henchmen shortly arrive and capture the trio. Charlie and Louis outsmart them, but find Frankie has tracked them down and is prepared to kill them. The kangaroo suddenly returns, causing a fist fight between Mr. Smith's henchmen and Frankie's crew, who outmatch them. The distraction allows Charlie, Louis and Jessie to escape. The duo chases after the kangaroo while being pursued by Frankie and his goons. Louis finally retrieves the money from the kangaroo, and Charlie narrowly saves him from falling off a cliff. Charlie tries to hand the money to Frankie, who angrily declines and reveals that Sal sent them to Australia to pay for their own execution at the hands of Mr. Smith. The police force, led by a cop working undercover as an Outback guide, arrives and arrests Frankie, Mr. Smith, and their henchmen. Charlie reclaims Louis' jacket from the kangaroo.

One year later, Charlie and Jessie are married and have used Sal's $50,000 to start a line of new hair care products bearing a kangaroo logo, along with Louis. Sal, Frankie, Mr. Smith, and their men have been imprisoned for life. The kangaroo, now called "Kangaroo Jack", continues to live happily in the Outback. Now able to speak again, Jack breaks the fourth wall, explaining why the film should end with him and closes it with his version of Porky Pig's famous catchphrase: "That's all, blokes!"

Cast

 * Jerry O'Connell as Charlie Carbone, the owner of a beauty salon.
 * Robert Reid as young Charlie Carbone
 * Anthony Anderson as Louis Booker, Charlie's best friend. Anderson also voices his kangaroo counterpart in Charlie's nightmare.
 * Shawn Smith as young Louis Booker
 * Estella Warren as Jessie, a member of the Outback Wildlife Foundation who helps Charlie and Louis and later becomes Charlie's wife.
 * Christopher Walken as Salvatore "Sal" Maggio, a mobster and Charlie's stepfather. Walken also voices his kangaroo counterpart in Charlie's nightmare.
 * Dyan Cannon as Anna Carbone, Charlie's mother
 * Michael Shannon as Frankie Lombardo, Sal's apprentice
 * Brian Casey as young Frankie Lombardo
 * Adam Garcia as Kangaroo Jack / "Jackie Legs" (voice, uncredited), a red kangaroo on whom Louis puts his "lucky jacket".
 * Marton Csokas as Mr. Smith, the intended recipient of Charlie and Louis's $50,000 package.
 * Bill Hunter as Blue, a pilot whom Charlie and Louis enlist to help catch Jack.
 * Tony Nikolakopoulos as Sal's Capo, an unnamed caporegime who works for Sal.
 * David Ngoombujarra as Sergeant Jimmy Inkamale, an Australian Police officer who works undercover.
 * Christopher James Baker as Crumble
 * Lara Cox as Cute Girl On Plane
 * Frank Welker as Special Vocal Effects
 * Denise Roberts as Tansy
 * Helen Thomson as TV announcer

Production
Initially the film was titled Down and Under and was shot as a mob comedy in the style of Midnight Run. The film began shooting in Australia in August 2001, lasting about six months in total, and originally included cursing, sex, and violence. However, the film's producers were dissatisfied by the first rough cut. Inspired by positive response to the kangaroo scene in early test screenings, as well as the marketing campaign behind the recently released Snow Dogs, the production shifted the marketing focus away from that of a dark mafia comedy to that of a family-friendly animal picture. Extensive new footage that replaced the animatronic kangaroo with a new CGI one that rapped was shot, and the film was edited down to a PG-rated family animal comedy. Even though Adam Garcia voiced Kangaroo Jack, he was not credited for the role.

Theatrical release
Kangaroo Jack was theatrically released on January 17, 2003, by Warner Bros. Pictures.

Home media
Kangaroo Jack was released on DVD and VHS on June 24, 2003, by Warner Home Video. The film was then re-released on DVD in 2011.

Box office
The film was released on January 17, 2003 and ranked No. 1 that weekend. It grossed $66,934,963 at the North American domestic box office and $21,994,148 internationally for a worldwide total of $88,929,111.

Critical response
Rotten Tomatoes reported that 9% of 115 critics gave the film a positive reviews, with an average rating of 3.4/10. The site's critics consensus reads: "The humor is gratingly dumb, and Kangaroo Jack contains too much violence and sexual innuendo for a family movie." On Metacritic it holds a weighted average score of 16 out of 100 based 25 critics, indicating "overwhelming dislike." Audiences polled by CinemaScore gave the film an average grade of "A−" on an A+ to F scale.

Joe McGovern in The Village Voice described Kangaroo Jack as "witless" and stated "The colorless script...seems to have written itself from a patchwork of Wile E. Coyote cartoons, camel farts, and every high-pitched Aussie cliché to have echoed on these shores". Nathan Rabin, reviewing the film for The A.V. Club, remarked "Kangaroo Jack's premise, trailer, and commercials promise little more than the spectacle of two enthusiastic actors being kicked over and over again by a sassy, computer-animated kangaroo—and, sadly, the film fails to deliver even that." Gary Slaymaker in the British newspaper The Western Mail wrote "Kangaroo Jack is the most witless, pointless, charmless drivel unleashed on an unsuspecting public".

Awards
For their performances, Anthony Anderson and Christopher Walken were both nominated for Worst Supporting Actor at the 24th Golden Raspberry Awards, but they lost to Sylvester Stallone for Spy Kids 3-D: Game Over. The Australian newspaper The Age included Kangaroo Jack on its list of "worst films ever made". However, the film won the Kids' Choice Award for Favorite Fart in a Movie (Anthony Anderson).

Soundtrack
The soundtrack was released by Hip-O Records on January 14, 2003.
 * 1) DJ Ötzi - "Hey Baby"
 * 2) Sugababes - "Round Round"
 * 3) Soft Cell - "Tainted Love"
 * 4) Lucia - "So Clever"
 * 5) Paulina Rubio - "Casanova"
 * 6) Shaggy - "Hey Sexy Lady"
 * 7) Shawn Desman - "Spread My Wings"
 * 8) Lil' Romeo - "2-Way"
 * 9) The Wiseguys - "Start the Commotion"
 * 10) The Sugarhill Gang - "Rapper's Delight"
 * 11) Men at Work - "Down Under"
 * 12) The Dude - "Rock Da Juice"

Animated sequel
The animated sequel Kangaroo Jack: G'Day U.S.A.! was released direct-to-video on November 16, 2004.

title: Kangaroo Jack


text:
User talk:Robi~enwiki

[US] I guess this is where I rant...

[HR] Izgleda ovdje se brblja...

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Robi. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Robi~enwiki that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name. If you think you might own all of the accounts with this name and this message is in error, please visit Special:MergeAccount to check and attach all of your accounts to prevent them from being renamed.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 02:43, 20 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 18:12, 22 April 2015 (UTC)

title: User talk:Robi~enwiki


text:
Sorrento

Sorrento (,, ; Surrentum) is a town overlooking the Bay of Naples in Southern Italy. A popular tourist destination, Sorrento is located on the Sorrentine Peninsula at the south-eastern terminus of the Circumvesuviana rail line, within easy access from Naples and Pompei. The town is widely known for its small ceramics, lacework and marquetry (woodwork) shops.

The Sorrentine Peninsula has views of Naples, Vesuvius and the Isle of Capri. The Amalfi Drive, connecting Sorrento and Amalfi, is a narrow road along the high cliffs above the Tyrrhenian Sea.

Ferries and hydrofoils connect the town to Naples, Amalfi, Positano, Capri and Ischia.

Limoncello, a digestif made from lemon rinds, alcohol, water and sugar, is produced in Sorrento along with citrus fruit, wine, nuts and olives.

Origins
The Roman name for Sorrento was Surrentum. From the 8th century BC the area had the presence of a community of indigenous villages, which was a crossing point for Etruscan traffic. Subsequently, the area fell into the hands of the Osci, who exercised an important influence there, in fact the oldest ruins of Surrentum are Oscan, dating from about 600 BC.

Before its control by the Roman Republic, Surrentum was one of the towns subject to Nuceria, and shared its fortunes up to the Social War; it seems to have joined in the revolt of 90 BC like Stabiae; and was reduced to obedience in the following year, when it seems to have received a colony.

Numerous sepulchral inscriptions of Imperial slaves and freedmen have been found at Surrentum. An inscription shows that Titus in the year after the earthquake of 79 AD restored the horologium (clock) of the town and its architectural decoration. A similar restoration of an unknown building in Naples in the same year is recorded in an inscription from the last-named town.

The most important temples of Surrentum were those of Athena and of the Sirens (the latter the only one in the Greek world in historic times); the former gave its name to the promontory. In antiquity, Surrentum was famous for its wine (oranges and lemons which are now widely cultivated there were not yet introduced in Italy in antiquity), its fish, and its red Campanian vases; the discovery of coins of Massilia, Gaul, and the Balearic Islands here indicates the extensive trade which it carried on.

The position of Surrentum was very secure, protected by deep gorges. The only exception to its natural protection was 300 m on the south-west where it was defended by walls, the line of which is necessarily followed by those of the modern town. The arrangement of the modern streets preserves that of the ancient town, and the disposition of the walled paths which divide the plain to the east seems to date in like manner from Roman times. No ruins are now preserved in the town itself, but there are many remains in the villa quarter to the east of the town on the road to Stabiae, of which traces still exist, running much higher than the modern road, across the mountain.

The site of one of the largest (possibly belonging to the Imperial house) is now occupied by the Hotel Vittoria, under the terrace of which a small theatre was found in 1855; an ancient rock-cut tunnel descends hence to the shore. Remains of other villas may be seen, but the most important ruin is the reservoir of the (subterranean) aqueducts just outside the town on the east, which had no less than twenty-seven chambers each about 270 by. Greek and Oscan tombs have also been found.

Another suburb lay below the town and on the promontory on the west of it; under the Hotel Bellevue Syrene are substructions and a rock-hewn tunnel. To the north-west on the Capo di Sorrento is another villa, the so-called Bagni della Regina Giovanna, with baths, and in the bay to the south-west was the villa of Pollius Felix, the friend of Statius, which he describes in Silvae ii. 2, of which remains still exist. Farther west again are villas, as far as the temple of Athena on the promontory named after her at the extremity of the peninsula (now Punta Campanella). Neither of this nor of the famous temple of the Sirens are any traces existing.

In the mythology, according to the Greek historian Diodorus Siculus, Sorrento was founded by Liparus, son of Ausonus, who was king of the Ausoni and the son of Ulysses and Circe. The ancient city was probably connected to the Ausoni tribe, one of the most ancient ethnic groups in the area. In the pre-Roman age, Sorrento was influenced by the Greek civilization: this can be seen in its plant and in the presence of the Athenaion, a great sanctuary, also, according to the legend, founded by Ulysses and originally devoted to the cult of the Sirens, hence Sorrento's name.

Middle Ages and modern era
Sorrento became an archbishopric around 420 AD. After the fall of the Western Roman Empire, it was ruled by the Ostrogoths and then returned to the Eastern Empire. The Lombards, who conquered much of southern Italy in the second half of the 6th century, besieged it in vain.

In the following centuries the authority of the distant Empire of Byzantium faded; initially part of the substantially independent Duchy of Naples, later Sorrento became in turn an autonomous duchy in the 9th century. It fought against neighbouring/rival Amalfi, the Saracens and the nearby Lombardic duchies, such as that of Duchy of Benevento, whose forces besieged it in 839, although Sorrento was able to resist with Neapolitan help. Sorrentine forces took part in the anti-Saracen leagues at the battles of Licosa (846) and Ostia (849). The duchy was ruled by figures elected by the people, which received honorary titles from the Byzantine Emperor.

In 1035 the city was acquired by Guaimar IV of Salerno, who gave it to his brother Guy. After a brief return under the Duchy of Naples, it returned in Lombard hands with Gisulf II of Salerno; when the latter was defeated by Robert Guiscard, Sorrento entered the Norman sphere of influence: any residual independence was ended in 1137 when it was conquered by Roger II of Sicily, and annexed to the Kingdom of Sicily.

On 13 June 1558 it was sacked by elements of the Ottoman navy under the command of Dragut and his lieutenant Piali, as part of the struggle between the Turks and Spain, which controlled the southern half of Italy at that time. 2,000 captives were reportedly taken away. This struggle was waged throughout the Mediterranean and lasted many decades. The attackers were not "pirates" as often characterised, though some may have been mercenaries from North Africa. The campaigns were conducted on the direct orders of Sultan Suleiman. The attack led to the construction of a new line of walls. The most striking event of the following century was the revolt against Spanish domination of 1648, led by Giovanni Grillo. In 1656 a plague struck the city. However, Sorrento remained one of the most important centres of southern Campania.

Sorrento entered into the Neapolitan Republic of 1799, but in vain.

In the 19th century the economy of the city improved markedly, favoured by the development of agriculture, tourism and trade. A route connecting Sorrento to Castellammare di Stabia was opened under the reign of Ferdinand II (1830–1859). In 1861 Sorrento was officially annexed to the new Kingdom of Italy. In the following years it confirmed and increased its status of one of the most renowned tourist destinations of Italy, a trend which continued into the 20th century. Famous people who visited it include Lord Byron, Keats, Goethe, Friedrich Nietzsche, Henrik Ibsen and Walter Scott.

Fortifications and castles
Having been a city victim of numerous attacks by pirates for its riches, Sorrento boasted in the past numerous castles and fortifications, especially on the strip of land that runs along the sea.

Sorrento, legends and myths
The myth of the Sirens has been loosely associated with Sorrento since antiquity. Three mermaids settled near Punta Campanella enchanting the seafarers sailing through those waters.

The beach of Queen Giovanna
A beach near to Sorrento natural swimming pool near the summer residence of the homonymous ruler. It is said that Queen Giovanna d'Angiò spent her summer holidays pleasantly in Sorrento. Having many lovers, she indulged them right on this beach. After taking advantage of them she had them drowned by her soldiers.

Rites of Holy week
The two main processions that take place in Sorrento on Good Friday are the Procession of Our Lady of Sorrows (or the "Visit in the Sepulchres"), organised by the Venerable Arciconfraternita of Saint Monica and the Procession of the Crucified Christ, organised by the Venerable Arciconfraternita of the Death.

Climate
Sorrento experiences a Mediterranean climate (Köppen climate classification Csa). with mild, wet winters and warm, dry summers. The mild climate and fertility of the Gulf of Naples made the region famous during Roman times, when emperors such as Claudius and Tiberius holidayed nearby. Temperatures can get as high as 29 °C in April, as happened in 2013.

Culture

Sorrento has been visited by Lord Byron, John Keats, Johann Wolfgang von Goethe, Charles Dickens, Richard Wagner, Henrik Ibsen, and Friedrich Nietzsche. Sorrento was the birthplace of the poet Torquato Tasso, author of the Gerusalemme Liberata. The town was featured in the early 20th century song "Torna a Surriento" (Come Back to Sorrento) with lyrics by Giambattista De Curtis, brother of the song's composer, Ernesto De Curtis.

In the 1920s, famous Soviet writer Maxim Gorky lived in Sorrento.

Songs that have featured Surrento prominently have included "Torna a Surriento" and "Caruso", a song composed in Sorrento, in the summer of 1985, by the Bolognese singer-songwriter Lucio Dalla, whose fifty-years ties with Sorrento are described in the novel by the Sorrentine writer, Raffaele Lauro, titled "Caruso The Song - Lucio Dalla and Sorrento", which was released in December 2014.

The local football team is Football Club Sorrento that plays at the Stadio Italia, and currently plays in the Eccellenza Campania of the Italian Football League.

Main sights

 * Amalfi Coast
 * Marina Grande, port of Sorrento
 * Marina Piccola, small port of Sorrento
 * Park of Villa communale with a view of the Gulf of Naples with the volcano Vesuvius
 * Piazza Tasso, central place in Sorrento
 * Sorrento funicular (1883-1886), remnants of the defunct inclined railway descending from Hotel Vittoria
 * Museo della tarsia lignea (intarsia)
 * Museum Correale (Museo Correale di Terranova), museum with small archeologic department
 * Via San Cesareo, Sorrento's main shopping street
 * Cathedral of Sorrento (Santi Filippo e Giacomo Cathedral), from the 14th century with façade reconstructed in 1924. It was built over time in different styles, with doors of the 11th century from Constantinople
 * Church of
 * Monastery of St Francesco, 14th century
 * Roman ruins at the Punta del Capo
 * Vallone dei Mulini (Valley of the Mills), see Vallone dei Mulini at Wikipedia Italiano

Transportation
Sorrento is served by ferry or hydrofoil from Naples or Capri as well as by boat services from the ports of the Bay of Naples and the Sorrentine Peninsula. Naples is served by two ports, Mergellina and Molo Beverello. Sorrento is connected to Naples by the Circumvesuviana rail line. Friends of Sorrento has details of buses serving Sorrento.

Airports
The nearest airports are:
 * Napoli-Capodichino (NAP) 53 km
 * Salerno-Pontecagnano (QSR) 75 km

Notable people

 * Antoninus of Sorrento (555 or 556 – 625), an Italian abbot, hermit and saint
 * Saint Baculus of Sorrento (7th c.), venerated as a Bishop of Sorrento
 * Nardo Mormile (died 1493), a Roman Catholic prelate, Archbishop of Sorrento 1480–1493
 * Antonius Agellius (1532 in Sorrento – 1608), Bishop of Acerno and a member of the Theatines
 * Torquato Tasso (1544–1595), Italian poet of the 16th century
 * Giuseppe Agellio (1570 in Sorrento – after 1620), an Italian painter of the Baroque period
 * Giacomo di Castro (c. 1597 in Sorrento – 1687), an Italian painter of the Baroque period
 * Sylvester Shchedrin (1791 – 1830 in Sorrento), a Russian landscape painter, emigrated to Italy in 1818
 * Edoardo De Martino CVO (1838 Meta di Sorrento – 1912) an Italian-British painter, mainly active in London, painted warships and marine battles
 * Bonaventura Gargiulo (1843–1904), Italian Capuchin friar, editor and publisher and Bishop of the Roman Catholic Diocese of San Severo
 * Friedrich Nietzsche (1844–1900), the German philosopher, was in Sorrento for six months in 1876. He there wrote Human, All Too Human
 * Maxim Gorky (1868–1936), a Russian and Soviet writer, a founder of the socialist realism literary method and a political activist, five-time nominee for the Nobel Prize in Literature. Lived in Sorrento during his second exile from 1921 to 1928
 * Aniello Califano (1870 in Sorrento – 1919), an Italian poet and writer, author of Neapolitan songs
 * Pasquale Troise (1895, in Minori village – 1957), mandolinist and bandleader, active in England from the 1920s.
 * Enrico Garff (born 1939), an Italian portrait painter and colourist, he has worked in Positano, Sorrento, Rome, Sicily and in Sweden and Finland
 * Raffaele Lauro (born 1944 in Sorrento), politician and writer

Twin towns – sister cities
Sorrento is twinned with:

 * Dubrovnik, Croatia
 * 🇮🇱 Eilat, Israel
 * 🇯🇵 Kumano, Japan
 * 🇦🇷 Mar del Plata, Argentina
 * 🇫🇷 Nice, France
 * 🇮🇹 San Martino Valle Caudina, Italy
 * 🇺🇸 Santa Fe, United States
 * 🇳🇴 Skien, Norway
 * 🇮🇹 Taurasi, Italy
 * 🇦🇺 Sorrento, Australia

title: Sorrento


text:
19th century in film

Events

 * 1826 – Nicéphore Niépce takes the oldest known extant photograph, View from the Window at Le Gras.
 * 1833 – Joseph Plateau (Belgium) introduces a scientific demonstration device that creates an optical illusion of movement by mounting drawings on the face of a slotted, spinning disk, later published as the Fantascope (and now better known as the Phenakistoscope). Simon von Stampfer (Vienna) publishes the very similar stroboscopic discs a few months later.
 * 1866 – The Zoetrope is introduced. The device was a hollow drum with a strip of pictures around its inner surface. When the drum was spun and the pictures viewed through slots on the side of the drum, the pictures appeared to move.
 * 1870s – French inventor Charles-Émile Reynaud improved on the Zoetrope idea by placing mirrors at the center of the drum. He called his invention the Praxinoscope. Reynaud developed other versions of the Praxinoscope too, including a Praxinoscope Theatre, where the device was enclosed in a viewing box, and the Projecting Praxinoscope. Eventually he created the "Théâtre Optique", a large machine based on the Praxinoscope, but able to project longer animated strips.
 * 1874 – Passage de Vénus is recorded as a series of still pictures on a disc with Jules Janssen's photographic revolver.
 * 1878 – Railroad tycoon Leland Stanford hires British photographer Eadweard Muybridge to settle arguments about the strides of horses that were difficult to discern with the naked eye. Muybridge successfully photographed successive positions of horses in fast motion, using a battery of 12 cameras controlled by trip wires and an electrical shutter system. Stanford's experiments were partly inspired by French scientist's Étienne-Jules Marey studies with equipment that graphically recorded data to analyze animal and human movement.
 * 1880 – Eadweard Muybridge holds a public demonstration of his Zoopraxiscope, a magic lantern provided with a rotating disc with artist's renderings of Muybridge's chronophotographic sequences. It was used as a demonstration device by Muybridge in his illustrated lecture (the original preserved in the Museum of Kingston upon Thames in England).
 * 1882 – American inventor George Eastman begins experimenting with new types of photographic film, with his employee, William Walker.
 * 1882 – French physiologist Étienne-Jules Marey develops his own version of Janssen's camera: a chronophotographic gun that could photograph twelve successive images per second.
 * 1885 – American inventors George Eastman and Hannibal Goodwin each invent a sensitized celluloid base roll photographic film to replace the glass plates then in use.
 * 1887 – German chronophotographer Ottomar Anschutz very successfully presents his photographs in motion with his Electrotachyscope that uses transparent pictures in a wheel.
 * 1887 – Hannibal Goodwin files for a patent for his photographic film.
 * 1888 – George Eastman files for a patent for his photographic film.
 * 1888 – Thomas Edison meets with Eadweard Muybridge to discuss adding sound to moving pictures. Edison begins his own experiments.
 * 1888 – Louis Aimé Augustin Le Prince creates the first motion picture films created on paper rolls of film.
 * 1889 – George Eastman's celluloid base roll photographic film becomes commercially available.
 * June 1889 or November 1890 – William K. L. Dickson, working for Thomas Edison, creates the first known motion picture films shot in the United States, the Monkeyshines films.
 * 1891 – Designed around the work of Anschutz, Muybridge, Marey, and Eastman, Thomas Edison's employee William K. L. Dickson finishes work on a motion-picture camera, called the Kinetograph, and a viewing machine, called the Kinetoscope.
 * May 20, 1891 – Thomas Edison holds the first public presentation of his Kinetoscope for the National Federation of Women's Clubs.
 * August 24, 1891 – Thomas Edison files for a patent of the Kinetoscope.
 * 1892 – Charles-Émile Reynaud begins public screenings in Paris at the Théâtre Optique, with hundreds of drawings on a reel that he wound through his Praxinoscope projector to construct moving image stories that continued for about 15 minutes each.
 * March 14, 1893 – Thomas Edison is granted Patent #493,426 for "An Apparatus for Exhibiting Photographs of Moving Objects" (the Kinetoscope).
 * 1893 – Thomas Edison builds a motion-picture studio, dubbed the "Black Maria" by his staff.
 * May 9, 1893 – In America, Thomas Edison holds the first public exhibition of films shot using his Kinetograph at the Brooklyn Institute. Only one person at a time could use his viewing machine, the Kinetoscope.
 * January 7, 1894 – Dickson and William Heise film "Fred Ott's Sneeze" with the Kinetoscope at "Edison's Black Maria".
 * April 14, 1894 – The first commercial presentation of the Kinetoscope takes place at the Holland Brothers' Kinetoscope Parlor at 1155 Broadway, New York City.
 * 1894 – Kinetoscope viewing parlors begin to open in major cities. Each parlor contains several machines.
 * November 1895 – In Germany, Emil and Max Skladanowsky start publicly screening their films with their Bioskop.
 * 1895 – In France, Gaumont, the world's oldest extant film studio, is founded as a producer of photographic equipment (the company would start production of films in 1897).
 * December 1895 – In France, Auguste and Louis Lumière hold their first commercial screenings of films shot with their Cinématographe, a lightweight, hand-held motion picture camera.
 * January 1896 – In Britain, Birt Acres and Robert W. Paul develop their own film projector, the Theatrograph (later known as the Animatograph).
 * January 1896 – In the United States, a projector called the Vitascope is designed by Charles Francis Jenkins and Thomas Armat. Armat began working with Thomas Edison to manufacture the Vitascope, which projected motion pictures.
 * January 26, 1896 – Brothers Auguste and Louis Lumière release L'Arrivée d'un train en gare de La Ciotat in France.
 * April 1896 – Thomas Edison and Thomas Armat's Vitascope is used to project motion pictures in public screenings in New York City
 * September 28, 1896 – Pathé-Frères is founded in Paris.
 * 1896 – French magician and filmmaker Georges Méliès begins experimenting with the new motion picture technology, developing many early special effects techniques.
 * May 4, 1897 – 125 people die during a film screening at the Bazar de la Charité in Paris after a curtain catches on fire from the ether used to fuel the projector lamp.
 * 1897 – Vitagraph Studios are established in New York City.
 * March 22, 1899 – London inventor Edward Raymond Turner applies for a patent for his additive colour process for colour motion picture film.
 * September 1899 – The British Mutoscope and Biograph Company makes King John (a very short silent film) in London, the first known film based on a Shakespeare play.
 * September 1899 – Georges Méliès releases The Dreyfus Affair film series in France, with the last episode featuring events of the current month.
 * October 1899 – Georges Méliès releases Cendrillon in France, the first screen adaptation of the traditional fairy tale "Cinderella".

Births

 * April 9, 1830 – Eadweard Muybridge, English photographer
 * February 11, 1847 – Thomas Edison, American inventor, businessman
 * April 20, 1851 – Siegmund Lubin, American motion picture pioneer
 * January 15, 1853 – Tom Ricketts, English actor, director
 * July 12, 1854 – George Eastman, American entrepreneur, founder of the Eastman Kodak Company, inventor of roll film
 * March 9, 1856 – Eddie Foy, American actor and dancer
 * February 14, 1859 – Justus Hagman, Swedish actor
 * February 20, 1860 – Karl Mantzius, Danish actor, theatre director and writer
 * August 24, 1861 – Dante Testa, Italian actor and director
 * December 8, 1861 – Georges Méliès, French filmmaker
 * December 20, 1861 – Ferdinand Bonn, German stage and film actor
 * November 4, 1862 – Rasmus Rasmussen, Norwegian stage and film actor
 * April 19, 1863 – Hemmo Kallio, Finnish stage and film actor
 * July 21, 1863 – C. Aubrey Smith, English-born actor and cricketer
 * November 4, 1863 – Harry Beresford, British actor
 * April 10, 1864 – Tully Marshall, American actor
 * June 9, 1864 – Jeanne Bérangère, French actress
 * November 19, 1864 – George Barbier, American actor
 * June 19, 1865 – May Whitty, English actress
 * January 6, 1866 – Harry Davenport, American actor
 * January 19, 1866 – Dante Cappelli, Italian actor
 * February 23, 1868 – Anna Hofman-Uddgren, Swedish actress
 * April 10, 1868 – George Arliss, English actor
 * November 9, 1868 – Marie Dressler, Canadian-American actress
 * April 15, 1869 – Harry C. Bradley, American actor
 * May 2, 1869 – Tyrone Power Sr., English-American actor
 * September 15, 1869 – Paweł Owerłło, Polish actor
 * December 20, 1869 – Charley Grapewin, American actor and writer

Deaths

 * c. September 16, 1890 – Louis Aimé Augustin Le Prince, French film pioneer

title: 19th century in film


text:
Stuart Bell

Sir Stuart Bell (16 May 1938 – 13 October 2012) was a British Labour Party politician, who was the Member of Parliament (MP) for Middlesbrough from the 1983 general election until his death in 2012. He was known as the longest serving Second Church Estates Commissioner, serving in this role during the entire period of Labour government from 1997–2010.

Early life
Bell was born in County Durham in 1938, the son of a miner. He studied at the Hookergate Grammar School on School Lane in High Spen near Rowlands Gill, Gateshead. He later attended the Durham Pitmans College. He joined the Labour Party in 1964, and was called to the Bar at Gray's Inn in 1970. He worked as an international lawyer in Paris until 1977, representing large multi-national companies. He contested Hexham at the 1979 general election, but was defeated by the Conservative MP and former Cabinet Minister Geoffrey Rippon.

Parliamentary career
Bell was elected to the City Council of Newcastle upon Tyne in 1980. In 1982, the Labour MP for Middlesbrough, Arthur Bottomley announced that he would step down at the next general election; Bell won the subsequent selection process to fight the seat at the 1983 general election. Bell comfortably held the seat, elected with a majority just short of 10,000 votes.

At Westminster, Bell became the Parliamentary Private Secretary to the Deputy Leader of the Opposition Roy Hattersley in 1983. He was promoted to the shadow frontbench in 1984 by Neil Kinnock as a Spokesman for Northern Ireland. However, he chose to resign his post after the Cleveland child abuse scandal which occupied two years of his life, after making unsubstantiated accusations of 'clinical error' against local paediatricians and child sexual abuse specialists. The paediatricians, Dr. Marietta Higgs and Dr. Geoffrey Wyatt, were later absolved and their forensic clinical work validated at a committee of inquiry overseen by Dame Elizabeth Butler-Sloss. The committee concluded that most of the diagnoses were incorrect. As a result, 94 of the 121 children were returned to their homes.

After the 1992 general election and the election of John Smith as the Leader of the Labour Party, Bell returned to the shadow frontbenches as a spokesman for Trade and Industry. After the election of the Labour Government at the 1997 general election he was dropped from Labour's frontbench, but was appointed on the advice of Tony Blair as the Second Church Estates Commissioner, the spokesman for the Church of England in the House of Commons, a position he held from 1997 to 2010.

From 2000 to 2005 he was the Chairman of the Finance and Services Committee, which manages the annual budget of the House of Commons and its many employees. In 2005 he became a member of the Finance and Services Committee until 2008 when he served as chairman until 2010. Relatedly, from 2000 until 2010 he was a member of the House of Commons Commission, which oversees the administration of the House and the Members Estimate Committee that sets MPs' pay and pensions. He was a member of the Liaison Committee between 2000–10. He was a member of the Ecclesiastical Committee from 1997.

Bell sat on the Members Estimates Committee at Parliament and was heavily involved representing MPs' interests in the MPs' expenses scandal of 2009. He was a member in Speaker's Committee for the Independent Parliamentary Standards Authority between 2009–10. A founder member of the British-Irish Inter-Parliamentary Body, he was a Treasurer of the All-Party Parliamentary Group for the Promotion of First Past the Post. and was Secretary of the Franco-British Parliamentary Relations Committee in the Commons. In February 2010 Bell was played by David Calder in the television film On Expenses.

Criticism and controversy
In 2002 his son, Malcolm, was jailed after admitting to stealing £8,000 from his father's colleagues, while he worked in Parliament.

On 13 October 2009, he claimed on the BBC Today programme that the investigation by Sir Thomas Legg into the United Kingdom Parliamentary expenses scandal was marked by "retrospectivity", as Sir Thomas had changed the rules on expenses after MPs' claims had been submitted.

Stuart Bell featured in a film of the 2010 general election entitled ToryBoy The Movie made by John Walsh, which explored the candidate's selection process and the work that goes into an election campaign. Later in 2011, Neil Macfarlane, in a report for local newspaper Teesside Gazette, asked "Are Teessiders getting enough from Sir Stuart Bell?" when he failed to answer over 100 telephone calls made to his constituency office over three months. The Gazette story was picked up by national newspapers. The Independent asked "is Sir Stuart Bell Britain's laziest MP?" The Guardian fact-checked the "laziest MP" claim and found that: "'Bell has been an MP for nearly 30 years and has had a distinguished career in parliament as a frontbench spokesman on trade and industry in opposition and the spokesman for the Church of England in the House of Commons and member of the House of Commons commission until last year. He's part of a breed of politicians – also including the Tory Edward Leigh and Labour's Gerald Kaufman – who have been extremely active parliamentarians but not always maintained an office in their constituency. One measure of their parliamentary work is the proportion of votes they turn up to... Bell's record doesn't cover him in glory, discounting frontbenchers, Northern Irish MPs, the Speaker and his deputies, he has the 10th worst attendance record with a 65.4% absence rate.'" The Labour Party said it was looking into the allegations.

Other interests
Bell was a member of the French think tank, the Fondation pour l'Innovation Politique. He was also a regular newspaper columnist for the Mail on Sunday and other publications.

Personal life
Bell was married in 1960 to Margaret Bruce and they had a son and a daughter. After his divorce, he married Margaret Allan in 1980 and they had a son.

Honours
Bell was knighted in 2004 for his "services to Parliament" and was appointed a Chevalier of the Légion d'honneur, France's highest order, by President Jacques Chirac in 2006.

Death
Bell died on 13 October 2012, aged 74, after a short battle with pancreatic cancer. A by-election was held in the Middlesbrough constituency.

Publications

title: Stuart Bell


text:
Laser cooling

[[File:Doppler laser cooling.svg|thumb|upright|200px|Simplified principle of Doppler laser cooling:

Laser cooling includes several techniques where atoms, molecules, and small mechanical systems are cooled with laser light. The directed energy of lasers is often associated with heating materials, e.g. laser cutting, so it can be counterintuitive that laser cooling often results in sample temperatures approaching absolute zero. It is a routine step in many atomic physics experiments where the laser-cooled atoms are then subsequently manipulated and measured, or in technologies, such as atom-based quantum computing architectures. Laser cooling relies on the change in momentum when an object, such as an atom, absorbs and re-emits a photon (a particle of light). For example, if laser light illuminates a warm cloud of atoms from all directions and the laser's frequency is tuned below an atomic resonance, the atoms will be cooled. This common type of laser cooling relies on the Doppler effect where individual atoms will preferentially absorb laser light from the direction opposite to the atom's motion. The absorbed light is re-emitted by the atom in a random direction. After repeated emission and absorption of light the net effect on the cloud of atoms is that they will expand more slowly. The slower expansion reflects a decrease in the velocity distribution of the atoms, which corresponds to a lower temperature and therefore the atoms have been cooled. For an ensemble of particles, their thermodynamic temperature is proportional to the variance in their velocity, therefore the lower the distribution of velocities, the lower temperature of the particles.

The 1997 Nobel Prize in Physics was awarded to Claude Cohen-Tannoudji, Steven Chu, and William Daniel Phillips "for development of methods to cool and trap atoms with laser light".

Radiation pressure
Radiation pressure is the force that electromagnetic radiation exerts on matter. In 1873 Maxwell published his treatise on electromagnetism in which he predicted radiation pressure. The force was experimentally demonstrated for the first time by Lebedev and reported at a conference in Paris in 1900, and later published in more detail in 1901. Following Lebedev's measurements Nichols and Hull also demonstrated the force of radiation pressure in 1901, with a refined measurement reported in 1903.

In 1933, Otto Frisch deflected an atomic beam of sodium atoms with light. This was the first realization of radiation pressure acting on a resonant absorber.

Laser cooling proposals
The introduction of lasers in atomic physics experiments was the precursor to the laser cooling proposals in the mid 1970s. Laser cooling was proposed separately in 1975 by two different research groups: Hänsch and Schawlow, and Wineland and Dehmelt. Both proposals outlined the simplest laser cooling process, known as Doppler cooling, where laser light tuned below an atom's resonant frequency is preferentially absorbed by atoms moving towards the laser and after absorption a photon is emitted in a random direction. This process is repeated many times and in a configuration with counterpropagating laser cooling light the velocity distribution of the atoms is reduced.

In 1977 Ashkin submitted a paper which describes how Doppler cooling could be used to provide the necessary damping to load atoms into an optical trap. In this work he emphasized how this process could allow for long spectroscopic measurements without the atoms escaping the trap and proposed the overlapping of optical traps in order to study interactions between different atoms.

Initial realizations
Following the laser cooling proposals, in 1978 two research groups that Wineland, Drullinger and Walls of NIST, and Neuhauser, Hohenstatt, Toscheck and Dehmelt of the University of Washington succeeded in laser cooling atoms. The NIST group wanted to reduce the effect of Doppler broadening on spectroscopy. They cooled magnesium ions in a Penning trap to below 40 K. The Washington group cooled barium ions. The research from both groups served to illustrate the mechanical properties of light. Around this time, laser cooling techniques had allowed for temperatures lowered to around $40 K$.

Influenced by the Wineland's work on laser cooling ions, William Phillips applied the same principles to laser cool neutral atoms. In 1982, he published the first paper where neutral atoms were laser cooled. The process used is now known as the Zeeman slower and is a standard technique for slowing an atomic beam.

Atoms

The Doppler cooling limit for electric dipole transitions is typically in the hundreds of microkelvins. In the 1980s this limit was seen as the lowest achievable temperature. It was a surprise then when sodium atoms were cooled to 43 microkelvin when their Doppler cooling limit is 240 microkelvin, this unforeseen low temperature was explained by considering the interaction of polarized laser light with more atomic states and transitions. Previous conceptions of laser cooling were decided to have been too simplistic. The major laser cooling breakthroughs in the 70s and 80s led to several improvements to preexisting technology and new discoveries with temperatures just above absolute zero. The cooling processes were utilized to make atomic clocks more accurate and to improve spectroscopic measurements, and led to the observation of a new state of matter at ultracold temperatures. The new state of matter, the Bose–Einstein condensate, was observed in 1995 by Eric Cornell, Carl Wieman, and Wolfgang Ketterle.

Molecules
In 2010, a team at Yale successfully laser-cooled a diatomic molecule. In 2016, a group at MPQ successfully cooled formaldehyde to $420 μK$ via optoelectric Sisyphus cooling. In 2022, a group at Harvard successfully laser cooled and trapped CaOH to $720 μK$ in a magneto-optical trap.

Mechanical systems
Starting in the 2000s, laser cooling was applied to small mechanical systems, ranging from small cantilevers to the mirrors used in the LIGO observatory. These devices are connected to a larger substrate, such as a mechanical membrane attached to a frame, or they are held in optical traps, in both cases the mechanical system is a harmonic oscillator. Laser cooling reduces the random vibrations of the mechanical oscillator, removing thermal phonons from the system.

In 2007, an MIT team successfully laser-cooled a macro-scale (1 gram) object to 0.8 K. In 2011, a team from the California Institute of Technology and the University of Vienna became the first to laser-cool a (10 μm × 1 μm) mechanical object to its quantum ground state.

Methods
The first example of laser cooling, and also still the most common method (so much so that it is still often referred to simply as 'laser cooling') is Doppler cooling.

Doppler cooling

Doppler cooling, which is usually accompanied by a magnetic trapping force to give a magneto-optical trap, is by far the most common method of laser cooling. It is used to cool low density gases down to the Doppler cooling limit, which for rubidium-85 is around 150 microkelvins.

In Doppler cooling, initially, the frequency of light is tuned slightly below an electronic transition in the atom. Because the light is detuned to the "red" (i.e., at lower frequency) of the transition, the atoms will absorb more photons if they move towards the light source, due to the Doppler effect. Thus if one applies light from two opposite directions, the atoms will always scatter more photons from the laser beam pointing opposite to their direction of motion. In each scattering event the atom loses a momentum equal to the momentum of the photon. If the atom, which is now in the excited state, then emits a photon spontaneously, it will be kicked by the same amount of momentum, but in a random direction. Since the initial momentum change is a pure loss (opposing the direction of motion), while the subsequent change is random, the probable result of the absorption and emission process is to reduce the momentum of the atom, and therefore its speed—provided its initial speed was larger than the recoil speed from scattering a single photon. If the absorption and emission are repeated many times, the average speed, and therefore the kinetic energy of the atom, will be reduced. Since the temperature of a group of atoms is a measure of the average random internal kinetic energy, this is equivalent to cooling the atoms.

Anti-Stokes cooling
The idea for anti-Stokes cooling was first advanced by Pringsheim in 1929. While Doppler cooling lowers the translational temperature of a sample, anti-Stokes cooling decreases the vibrational or phonon excitation of a medium. This is accomplished by pumping a substance with a laser beam from a low-lying energy state to a higher one with subsequent emission to an even lower-lying energy state. The principal condition for efficient cooling is that the anti-Stokes emission rate to the final state be significantly larger than that to other states as well as the nonradiative relaxation rate. Because vibrational or phonon energy can be many orders of magnitude larger than the energy associated with Doppler broadening, the efficiency of heat removal per laser photon expended for anti-Stokes cooling can be correspondingly larger than that for Doppler cooling. The anti-Stokes cooling effect was first demonstrated by Djeu and Whitney in CO2 gas. The first anti-Stokes cooling in a solid was demonstrated by Epstein et al. in 1980, in a ytterbium doped fluoride glass sample.

Potential practical applications for anti-Stokes cooling of solids include radiation balanced solid state lasers and vibration-free optical refrigeration.

Other methods
Other methods of laser cooling include:
 * Sisyphus cooling
 * Resolved sideband cooling
 * Raman sideband cooling
 * Velocity selective coherent population trapping (VSCPT)
 * Gray molasses
 * Optical molasses
 * Cavity-mediated cooling
 * Use of a Zeeman slower
 * Electromagnetically induced transparency (EIT) cooling
 * Anti-Stokes cooling in solids
 * Polarization gradient cooling

Applications
Laser cooling is very common in the field of atomic physics. Reducing the random motion of atoms has several benefits, including the ability to trap atoms with optical or magnetic fields. Spectroscopic measurements of a cold atomic sample will also have reduced systematic uncertainties due to thermal motion.

Often multiple laser cooling techniques are used in a single experiment to prepare a cold sample of atoms, which is then subsequently manipulated and measured. In a representative experiment a vapor of strontium atoms is generated in a hot oven that exit the oven as an atomic beam. After leaving the oven the atoms are Doppler cooled in two dimensions transverse to their motion to reduce loss of atoms due to divergence of the atomic beam. The atomic beam is then slowed and cooled with a Zeeman slower to optimize the atom loading efficiency into a magneto-optical trap (MOT), which Doppler cools the atoms, that operates on the $1$S$0$ → $1$P$1$ with lasers at 461 nm. The MOT transitions from using light at 461 nm to using light at 689 nm to drive the $1$S$0$ → $3$P$1$, which is a narrow transition, to realize even colder atoms. The atoms are then transferred into an optical dipole trap where evaporative cooling gets them to temperatures where they can be effectively loaded into an optical lattice.

Laser cooling is important for quantum computing efforts based on neutral atoms and trapped atomic ions. In an ion trap Doppler cooling reduces the random motion of the ions so they form a well-ordered crystal structure in the trap. After Doppler cooling the ions are often cooled to their motional ground state to reduce decoherence during quantum gates between ions.

Additional sources

 * Laser Cooling HyperPhysics
 * PhysicsWorld series of articles by Chad Orzel:
 * Cold: how physicists learned to manipulate and move particles with laser cooling
 * Colder: how physicists beat the theoretical limit for laser cooling and laid the foundations for a quantum revolution
 * Coldest: how a letter to Einstein and advances in laser-cooling technology led physicists to new quantum states of matter
 * Cold: how physicists learned to manipulate and move particles with laser cooling
 * Colder: how physicists beat the theoretical limit for laser cooling and laid the foundations for a quantum revolution
 * Coldest: how a letter to Einstein and advances in laser-cooling technology led physicists to new quantum states of matter

title: Laser cooling


text:
Subsonic

Subsonic may refer to:

Motion through a medium

 * Any speed lower than the speed of sound within a sound-propagating medium
 * Subsonic aircraft, a flying machine that flies at air speeds lower than the speed of sound
 * Subsonic ammunition, a type of bullet designed to avoid creating a loud shockwave when fired
 * Subsonic flight, an aircraft flight at air speeds lower than the speed of sound in air
 * Subsonic and transonic wind tunnels

Music

 * Subsonic (album), a 2002 album by Vigleik Storaas Trio
 * Subsonic (EP), a 2013 EP by Younha
 * Subsonic album series:
 * Subsonic 2: Bass Terror, a 1995 album by Bill Laswell and Nicholas Bullen
 * Subsonic 3: Skinner's Black Laboratories, a 1995 album by Andy Hawkins and Justin Broadrick
 * Subsonic Music Festival, an annual electronic music festival in Monkerai, Australia

title: Subsonic