Nova

A nova (plural novae or novas) is a cataclysmic nuclear explosion on a white dwarf, which causes a sudden brightening of the star. Novae are not to be confused with other brightening phenomena such as supernovae or luminous red novae. Novae are thought to occur on the surface of a white dwarf in a binary system when they are sufficiently near to one another, allowing material (mostly hydrogen) to be pulled from the companion star's surface onto the white dwarf. The nova is the result of the rapid fusion of the accreted hydrogen on the surface of the star, commencing a runaway fusion reaction.

Development

The development begins with two main sequence stars in a binary relation. One of the two evolves into a red giant leaving its remnant white dwarf core in orbit with the remaining star. The second star—which may be either a main sequence star, or an aging giant one as well—begins to shed its envelope onto its white dwarf companion when it overflows its Roche lobe. As a result, the white dwarf will steadily accrete matter from the companion's outer atmosphere; the white dwarf consists of degenerate matter, so the accreted hydrogen does not inflate as its temperature increases. Rapid, uncontrolled fusion occurs when the temperature of this accreted layer reaches ~20 million kelvin, initiating a burn via the CNO cycle.

Nova (eikaiwa)

Nova (formerly Nova Group) is a large eikaiwa school (private English teaching company) in Japan. It was by far the largest company of this type until its widely publicized collapse in October 2007. Before its bankruptcy, Nova employed approximately 15,000 people across a group of companies that supported the operations of and extended out from the "Intercultural Network" of its language schools. The scope of its business operations reached its peak in February 2007 following a rapid expansion of its chain to 924 Nova branches plus a Multimedia Center located in Osaka.

Nova, known for high-priced lesson packages, and later plagued by lawsuits and negative publicity, began to decline in earnest almost immediately after the Ministry of Economy, Trade and Industry placed a six-month ban against soliciting new long-term contracts from students on the company on 13 June 2007. The impending financial crisis facing Nova related to a rapid increase in refund claims, significant drops in sales figures, and deterioration of its reputation, came to the fore in September 2007 when Nova began to delay payment of wages and bonuses to staff. The NAMBU Foreign Workers Caucus in Tokyo estimated that up to 3,000 staff had not received their salaries on time. A solution for Nova's failure to pay wages was promised by 19 October in a fax sent to branch schools. On 23 October the Osaka Labor Standards office accepted a demand by unionized Nova instructors to investigate criminal charges against Nova President and founder, Nozomu Sahashi, over delayed and unpaid wages, but Sahashi was ultimately not charged.

Malta (band)

Malta was a Swedish band. It was a duo consisting of Claes af Geijerstam and Göran Fristorp. In 1973, they had to change their band name to Nova in order to perform at the Eurovision Song Contest 1973 to perform the song "You're Summer" in Luxembourg, which would put them in 5th place.

References

Tak (function)

In computer science, the Tak function is a recursive function, named after Ikuo Takeuchi (竹内郁雄). It is defined as follows:

This function is often used as a benchmark for languages with optimization for recursion.

tak() vs. tarai()

The original definition by Takeuchi was as follows:

tarai is short for tarai mawashi, "to pass around" in Japanese.

John McCarthy named this function tak() after Takeuchi.

However, in certain later references, the y somehow got turned into the z. This is a small, but significant difference because the original version benefits significantly by lazy evaluation. Though written in exactly the same manner as others, the Haskell code below runs much faster.

You can easily accelerate this function via memoization yet lazy evaluation still wins.

The best known way to optimize tarai is to use mutually recursive helper function as follows.

Here is an efficient implementation of tarai() in C:

Note the additional check for (x <= y) before z (the third argument) is evaluated, avoiding unnecessary recursive evaluation.

Tak (town)

Tak is a town (thesaban mueang) in north-west Thailand, capital of the Tak Province and the Tak district. As of 2005 the town had a population of 19,900 and an area of 7.27 km². It covers the tambon Rahaeng, Nong Luang, Chiang Ngoen, and Hua Diat. It is on the Ping River, 418 km north-north-west of Bangkok.

Geography

Tak is on the Ping River, which runs from north to south through the town. While the land to the east is fairly flat, the Tenasserim Hills and Dawna Range lie to the west.

Climate

Tak has a tropical savanna climate (Köppen climate classification Aw). Winters are dry and very warm. Temperatures rise until April, which is very hot with the average daily maximum at 38.5 °C (101.3 °F). The monsoon season runs from May through October, with heavy rain and somewhat cooler temperatures during the day, although nights remain warm.

Transportation

Route 105, through Mae Sot, forms one of two major transnational roads through the Tenasserim Hills to Burma. Route 1, also known as the Phahonyothin Road, passes through Tak. On the north side it leads to Lampang, Chiang Rai, and the border with Burma at Mae Sai. On the south side it leads to Kamphaeng Phet, Nakhon Sawan, and Bangkok. Route 12 leads east to Sukhothai, Phitsanulok, Chum Phae, Khon Kaen, Kalasin, and the border with Laos at Mukdahan.