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Acceleration clause

An acceleration clause, in the law of contracts, is a term that fully matures the performance due from a party upon a breach of the contract. Such clauses are most prevalent in mortgages and similar contracts to purchase real estate in installments.

Suppose, for example, the contract was for A to purchase Blackacre from B for $100,000, to be paid in 5 monthly installments of $20,000. If A makes the first two payments, but fails to make the third payment, an acceleration clause would require that A must immediately pay B the entire balance of $60,000, or lose his right to purchase Blackacre (without getting a refund of his $40,000).

A sample acceleration clause reads like this:

In the event of default in the payment of any of the said installments or said interest when due as herein provided, time being of the essence hereof, the holder of this note may, without notice or demand, declare the entire principal sum then unpaid immediately due and payable.


External links

  • Promissory Note - Installment - With Acceleration Clause

Joint lock

A joint lock is a grappling technique involving manipulation of an opponent’s joints in such a way that the joints reach their maximal degree of motion.

In budo these are referred to as, 関節技 kansetsu-waza, “joint locking technique”<ref>Ohlenkamp, Neil. Classification of Techniques in Kodokan Judo. judoinfo.com. Accessed February 26 2006.</ref>) and in Chinese martial arts as Chin na su which literally means “technique of catching and locking”.

These typically involve isolating a particular joint, and leveraging it in an attempt to force the joint to move past its normal range of motion. Joint locks usually involve varying degrees of pain in the joints, and if applied forcefully and/or suddenly, may cause injury, such as muscle, tendon and ligament damage, even dislocation, or bone fractures.

Joint locks can be divided into five general types according to which section of the body they affect:

  • Armlocks
  • Leglocks
  • Small joint manipulation
  • Spinal locks
  • Wristlocks

These general types can be further divided into subtypes according to which specific joint(s) they affect, or the type of motion they involve.


Usage

Joint locks are commonly featured in all forms of grappling, whether it be in martial arts, self-defense, combat sport or hand to hand combat application. The variants involving lesser leverage on a smaller joint (such as wristlocks) are often featured in law-enforcement or self-defense application, where they are used as pain compliance holds. Joint locks that involve full body leverage can on the other hand be used in hand to hand combat to partially or fully disable an opponent, by tearing major joints such as knees or elbows.

Common martial arts featuring joint locks include Aikido, Brazilian Jiu-Jitsu, Catch Wrestling, Hapkido, Jiu-Jitsu, Judo, Ninjutsu and mixed martial arts. They are usually practiced in a maximally safe manner, with controlled movements, and releasing the joint lock once it is apparent that it has been effectively applied. In combat sports, joint locks are used as submission holds, and are intended to force the opponent to submit; the lock will be controlled and held until an opponent submits or a referee recognizes the threat of injury and intervenes. The types of joint locks allowed in competitions featuring them varies according to the perceived danger in their application. Armlocks are generally considered safer, while small joint manipulation and spinal locks are banned in nearly all combat sports.


See also

  • Armlock
  • Chokehold
  • Compression lock
  • Grappling hold
  • Leglock
  • Small joint manipulation
  • Spinal lock
  • Wristlock


References

  • Iverson, Steven. Unarmed Combat. Online excerpt: Atlasbooks. www.atlasbooks.com. Accessed March 6 2006.

Transaction

A transaction is an agreement, communication, or movement carried out between separate entities or objects, often involving the exchange of items of value, such as information, goods, services and money.

  • Financial transaction
  • Database transaction
  • Atomic transaction
  • Transaction processing
  • POS Transaction

Transaction may also refer to:

  • Transaction,” an episode of the Death Note anime series, see List of Death Note episodes

Durability (database systems)

In database systems, durability is the ACID property that guarantees that transactions that are successfully committed will survive permanently and will not be undone by system failure.

For example, if a flight booking database system reports that a seat has successfully been booked, then the seat will remain booked even if the system crashes. Durability also guarantees that the system will not rollback the transaction because the seat was double-booked. (The system must check this before it acknowledges the seat has been booked)

The only way a transaction can be undone after it has been committed is by a compensatory transaction.

Durability is usually implemented by flushing the transaction’s log records to disk before acknowledging commitment. In distributed transactions, all participating servers must acknowledge that they have stored all data and checked all consistency constraints before commit can be acknowledged. This is usually done by a two-phase commit protocol.


See also

  • atomicity
  • consistency
  • isolation
  • relational database management system

Record locking

Record locking is the technique of preventing simultaneous access to data in a database, to prevent inconsistent results.

The classic example is demonstrated by two bank clerks attempting to update the same bank account for two different transactions. Clerk 1 and clerk 2 both retrieve (ie, copy) the account’s current balance. Clerk 1 applies one transaction and refiles the new balance. Clerk 2 applies a different transaction and refiles a new balance that obliterates the information saved by clerk 1. The resulting account balance no longer reflects the first transaction.

To prevent inconsistencies created by that kind of unlimited access, the account’s record can instead be immediately locked upon being retrieved for any subsequent update. Anyone attempting to retrieve the same record for editing is denied access because of the lock (although, depending on the implementation, they may be able to view the record without editing it). Once the record is saved or edits are canceled, the lock is released, thereby always insuring consistent data within the record being edited.


Use of locks

Record locks (hereafter lock(s)) need to be managed between the entities requesting the records such that no entity is given too much service via successive grants, and no other entity is effectively locked out. Care should also be used to avoid a deadlock condition which can bring the application or system to a halt. The entities that request a lock can be either individual applications (programs) or an entire processor.

The application or system should be designed such that any lock is held for the shortest amount of time possible. Given that there may be considerable overhead to the process of requesting, and subsequent granting of a lock, it may make sense to investigate if an entity can forego a lock if the purpose is simply to read non-critical data.

There are two main types of locks that can be requested:


Exclusive locks

Exclusive locks are as the name implies, exclusively held by a single entity. If the locking schema was represented by a list, the holder list would contain only one entry. Since this type of lock effectively blocks any other entity that requires the lock from processing, care must be used to:

  • Ensure the lock is held for the least amount of time possible
  • Do not hold the lock across system/function calls where the entity is no longer running on the processor - this can lead to deadlock
  • Ensure that if the entity is unexpectedly exited for any reason, the lock is freed otherwise deadlock will likely occur.

Non-holders of the lock (aka waiters) should perhaps be maintained in a list that is serviced in a round robin fashion. This would ensure that any possible waiter would get equal chance to obtain the lock and not be locked out. To further speed up the process, if an entity has gone to sleep waiting for a lock, performance is improved if the entity is notified of the grant, instead of discovering it on some sort of system timeout driven wakeup.


Shared locks

Cookham Lock

Cookham Lock is a lock and weir situated on the River Thames near Cookham, Berkshire. It is owned and managed by the Environment Agency. The lock is set in a lock cut which creates Formosa Island and it is surrounded by woods.


Access to the lock

There is a road from Cookham to Formosa Island and the lock.


Reach above the lock

The river is picturesque and described as Wind in the Willows country. Kenneth Graham based much of his book on this part of the Thames.


Literature and the Media

Cookham was home to the artist Stanley Spencer’s whose works include Swan Upping at Cookham.


See also

  • Locks on the River Thames
  • Cookham Bridge
  • Cookham Lock Cut Bridge

Tubular lock pick

A tubular lock pick is a specialized lockpicking tool used for opening a tubular pin tumbler lock. Tubular lock picks are all very similar in design and come in sizes to fit all major tubular locks, including 6, 7, and 8-pin locks.

The tool is simply inserted into the lock and turned clockwise with medium tension. As the tool is pushed into the lock, each of the picks is slowly forced down until they stop, thus binding the driver pins behind the shear line of the lock. When the final pick is pushed down, the shear plane is clear and the lock opens. This can usually be accomplished in a matter of seconds.

Most tubular lock picks come with a “decoder” which lets the locksmith know at what depths the pins broke the shear plane. By using the decoding key after the lock has been picked, the locksmith can cut a tubular key to the correct pin depths and thus avoid having to replace the lock.

In 2004 it was widely publicized that the barrel of a cheap ballpoint pen would act as an effective lock pick for many brands of tubular lock.


External links

  • Large picture of a Southord tubular lock pick
  • Tubular lock picks for sale on froogle
  • Devonlocks.com’s guide to using a Southord tubular lock pick

Guard Lock

A Guard Lock or Tide Lock is a canal lock located between a canal and a body of water of varying depth such as a harbor or a river. When the canal is at a different level than the open body, such a lock allows ships and boats to pass into and out of the canal regardless of the water level or tide.

Legacy for the Future

Legacy for the Future was Japan’s first television documentary miniseries.

Run on NHK for seventeen installments in 1974 and 1975, the theme of the program was “why civilizations flourished and declined.” Footage was seen from over 150 world heritage sites in 44 countries. An experimental series of programs, Legacy for the Future paved the way for the modern Japanese television documentary that NHK has since become known for.

Art gallery theorem

The art gallery theorem (sometimes called Chvátal’s art gallery theorem, after Václav Chvátal) states that in an art gallery with <math>n</math> different corners, there needs to be at most <math>\lfloor n/3 \rfloor</math> (see floor function) watchmen positioned in the corners to watch over the entire gallery. More specifically

Given a simple polygon on <math>n</math> vertices, the number of people posted at the vertices needed to view every point in it is <math>\lfloor n/3 \rfloor</math>

The result is the same if the restriction to guards at corners is loosened to
guards at any point not exterior to the polygon.
The question about how many vertices/watchmen were needed was posed to Chvátal by Victor Klee in 1973. Chvátal proved it shortly thereafter. Chvátal’s proof was later simplified by Steve Fisk, via a 3-coloring argument.

The problem of finding the minimum number of guards required for a specific art gallery is known as the art gallery problem. This specific problem has been
proven intractable, i.e., NP-Complete.

There are a number of generalizations and specializations of the original art-gallery theorem. One of the cleanest specializes to orthogonal polygons, those whose
edges/walls meet at right angles. For these polygons, rather than <math>\lfloor n/3 \rfloor</math>, only <math>\lfloor n/4 \rfloor</math> guards are needed.
Thus, for n=100, only 25 rather than 33 guards are needed to guard the interior.
(There are at least three distinct proofs of this result, none of them simple:
by Kahn, Klawe, and Kleitman; by Lubiw; and by Sack.)

A related problem asks for the number of guards to cover
the exterior of an abribrary polygon (the “Fortress Problem”):
<math>\lceil n/2 \rceil</math> are sometimes necessary and always sufficient.
So the infinite exterior is more challenging to cover than the finite interior:
a 100-vertex fortress might need 50 guards.


External links

  • Chvatal’s Art Gallery Theorem at cut-the-knot.


References

The results mentioned in this article may be found in

See also

Miraflores (Panama)

Miraflores is the name of one of the three locks that form part of the Panama Canal and the name of the small lake that separates these locks from the Pedro Miguel locks upstream. In the Miraflores locks, vessels are lifted (or lowered) in three stages totalling 8 m, allowing them to transit to or from the Pacific Ocean port of Balboa (near Panama City). Ships cross below the Puente de las Américas (Bridge of the Americas) which connects North and South America.

As of 2005, the following schedule was in effect for ship transit through the locks. From 06:00 to 15:15, ships travel from the Pacific towards the Atlantic. From 15:45 to 23:00 ships travel from the Atlantic towards the Pacific. At any other time, travel is permitted in both directions,

A modern visitor center allows tourists to have a full view of the Miraflores locks operation. Binoculars are recommended to also see the Pedro Miguel locks, visible in the distance. As of 2005, admittance to the visitors center costs US$5 (observation terrace) or $8 (supporting exhibits and show added). Viewing a transit operation at the center can take more than 30 minutes. A souvernirs shop in the base level sells related merchandise. The center closes at 17:00.

Asphalt: Urban GT 2

Asphalt: Urban GT 2 is a 3D racing game which was developed and published by Gameloft in 2005, following the success of the previous year’s Asphalt: Urban GT game of 2004. The game also features a special appearance from The Pussycat Dolls, and a sample of Moby’s hit single “Lift Me Up”. The game was released in different variations, which differed drastically because of device limitations - the Java versions for mobile phones were made into a pseudo-3D game because of memory, hardware and software limitations that cellphone manufacturers made to their phones in order to keep the price down. The Nintendo DS version was released approximately a year after the N-Gage version, with improved graphics, sound, and dual screen compatibility. A PSP version has been confirmed as well, and is slated to be released in March of 2007.


Gameplay

The gameplay of Urban GT 2 is often compared to Burnout, Need for Speed and other titles because players can eliminate opponents (by bumping them), as well as avoiding the police. There is a “WANTED” meter which determines the awareness level of the police, much like the Wanted meter in Grand Theft Auto - if the red WANTED light flashes it usually means that the players must do what it takes to avoid the police - otherwise they might lose their money.


External links

  • Gameloft official site
  • Pussycat Dolls official website
  • Asphalt: Urban GT 2 on Gamespot

Unenforceable

An unenforceable contract or transaction is one that is valid, but which the court will not enforce. Unenforceable is usually used in contradistinction to void (or void ab initio) and voidable. If the parties perform the agreement, it will be valid, but the court will not compel them if they do not.

An example of a transaction which is an unenforceable contract is a contract for prostitution under English law. Prostitution is not actually a crime under English law,<ref>Although both soliciting a prostitute and living off the earnings of a prostitute are criminal offences</ref> but so long as the contract is fully performed, it remains valid. However, if either refuses to complete the bargain (either the prostitute after being paid, or the payor after receiving the service) then the court will not assist the disappointed party. Similarly under English law, a gambling contract is valid, but unenforceable (gambling contracts are sometimes said to be “binding in honour only”). If a bookmaker refuses to pay out on a bet, then the punter has no legal recourse.<ref>Not even for a return of his original stake</ref>


Footnotes

Influence peddling

Influence peddling is the illegal practice of using one’s influence in government or connections with persons in authority to obtain favors or preferential treatment for another, usually in return for payment. Also called traffic of influence.


See also

  • Political corruption
  • bribery
  • logrolling

Readers-writer lock

In computer science, a readers-writer lock (also known by the name multi-reader lock, or by typographical variants such as readers/writers lock) is a synchronization primitive that solves one of the readers-writers problems. A readers-writer lock is like a mutex, in that it controls access to some shared memory area, but it allows multiple threads to read from the shared area concurrently. Any thread that needs to write to the shared memory, of course, needs to acquire an exclusive lock.

Readers-writer locks are usually constructed on top of mutexes and condition variables, or on top of semaphores. They are rarely implemented from scratch.

Delivery versus payment

Delivery versus payment is used to classify a security trade. DVP trading is defined as transactions in which payment and transfer of the subject security occur simultaneously where:

  • little or no credit risk exists in the settlement process (e.g. central depository system such as DTC or Euroclear), and
  • the settlement period is the normal spot settlement period for the product and market, and
  • the transaction does not create credit risk after settlement.

Any transaction entered into with a negotiated settlement period beyond the normal cash settlement date for the particular product and market and any transaction with a settlement date more than 45 days from trade date is not considered a DVP transaction.

There is also non-DVP trading.

Conservative two-phase locking

In computer science, conservative two-phase locking (C2PL) is a locking method used in DBMS and relational databases.

Conservative 2PL prevents deadlocks.

The difference between 2PL and C2PL is that C2PL’s transactions obtain all the locks they need before the transactions begin. This is to ensure that a transaction that already holds some locks will not block waiting for other locks.

In heavy lock contention, C2PL reduces the time locks are held on average, relative to 2PL and Strict 2PL, because transactions that hold locks are never blocked.

In light lock contention, C2PL holds more locks than is necessary, because it is hard to tell what locks will be needed in the future, thus leads to higher overhead.

Also, a transaction will not even obtain any locks if it cannot obtain all the locks it needs in its initial request. Furthermore, each transaction needs to declare its read and write set (data items to be read/written during transaction), which is not always possible. Because of these limitations, C2PL is not used very frequently.

Fulton Lock

The Fulton Lock (formerly named Lock C) is part of the Tennessee-Tombigbee Waterway. It is located close to Fulton, Mississippi.

Hatherton Canal

The Hatherton Canal is a derelict branch of the Staffordshire and Worcestershire Canal in south Staffordshire, England.

When it was built it ran 4 miles (6 km) through eight locks from Hatherton Junction on the Staffordshire and Worcestershire Canal to Churchbridge Junction on the Churchbridge Branch (a short branch with thirteen locks) of the Cannock Extension Canal (a branch of the Wyrley and Essington Canal). It was completed in 1860. Subsidence due to mining caused its closure in 1955.

The canal is now part of an active restoration project. However, due to building on the cut, the current plans call for the canal to deviate from the original route in places. This includes new tunnels under the A5 road and a cluvert, already in place, over the M6 Toll motorway.


See also

  • Canals of Great Britain
  • History of the British canal system


External links

  • Lichfield & Hatherton Canals Restoration Trust

Door furniture

Door furniture (British and Australian English) or Door hardware (North American English) refers to any of the items that are attached to a door or a drawer to enhance its functionality or appearance.

Design of door furniture is an issue to disabled persons who might have difficulty opening or using some kinds of door, and to specialists in Interior design as well as those usability professionals which often take their didactic examples from door furniture design and use.

Items of door furniture or door hardware include:

  • fingerplate
  • keyhole
  • lock
  • doorknob (or doorhandle)
  • door knocker
  • thumb latch
  • hinge
  • pull handle
  • letter plate (or letter box)
  • peephole or wide-angle door viewer
  • door stop
  • escutcheon
  • bell push
  • espagnolette
  • rim lock