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Jaffa Road

Jaffa Road is one of the longest and oldest major streets in Jerusalem, Israel. It crosses the city from east to west, from the Old City walls to downtown Jerusalem, the western portal of Jerusalem and the Jerusalem-Tel Aviv highway, it is lined with shops and restaurants. It joins with Ben Yehuda Street and King George Street to form the Downtown Triangle central business district. Major landmarks along Jaffa Road are Tzahal Square, Safra Square, Zion Square, Davidka Square, the triple intersection at King George V Street and Straus Street, the Ben Yehuda Street pedestrian mall, the Mahane Yehuda market, the Jerusalem Central Bus Station. Jaffa Road has been redeveloped as a car-free pedestrian mall served by the Jerusalem Light Rail. Paved in 1861 as part of the highway to Jaffa, the road became a focal point for the 19th century expansion out of Jerusalem's Old City walls, early neighbourhoods like the Russian Compound, Nahalat Shiva, Mahane Yehuda blossomed around it, as well as Shaare Zedek hospital.

Proximity to the artery became a measure of real-estate value in the booming city. Traffic consisted of camels and mules, the route was improved enough to allow for horse-drawn carriages; the German Templers, who established the German Colony, first began a regular carriage service along the road to Jaffa. During the period of the British Mandate, the street was further developed with the establishment of many central institutions including the city hall, the city's central post office, the Anglo-Palestine Bank, the Generali office building; the buildings on its easternmost end constructed along the Old City walls were destroyed in July 1944 so as not to obscure the city's historic view. During this period the street took on its modern shape, it became the heart of the city's developing central business district as most commerce left the Old City. During the city's 19-year division between Israel and Jordan after the 1948 Arab-Israeli War, which separated the Old City from much of modern Jerusalem, Jaffa Road's primacy as the city-centre was unchallenged.

The Jerusalem Municipality, Jerusalem's main post office, the Mahane Yehuda Market are located on Jaffa Road. As a bustling thoroughfare, it has been targeted by terrorist groups and some of the most devastating terrorist attacks from the late 1960s onward have been carried out on this street, among them the Zion Square refrigerator bombing and the Sbarro pizza bombing. For much of its hundred-year existence, Jaffa Road has served as Jerusalem's central artery; the municipality responded to problems in the struggling city-centre through focused efforts to redevelop the street. A tunnel was excavated under the street at Tzahal Square in 2004 to allow the city's central north-south route to bypass it. In order to accommodate the new system, new utility lines were laid under one side of the road, widened. 180 properties were evacuated to allow for the road's improvement. The Jerusalem Light Rail began operating in 2011. At the western end of Jaffa Road, opposite the Central Bus Station, it passes over Jaffa Road via Santiago Calatrava's Chords Bridge, which serves as an architectural beacon for the area.

Jaffa Road history on the Jerusalem Municipality website

List of UEFA Champions League hat-tricks

Since the inception of the UEFA Champions League in 1992, 86 players from 35 countries have scored three goals or more in a single match on a total of 128 occasions for 48 different clubs from 17 different leagues. The first player to achieve the feat was Juul Ellerman, who scored three times for PSV Eindhoven in a 6–0 victory over FK Vilnius on 16 September 1992. Thirteen players have scored four or more goals in a match. Only Messi and Luiz Adriano have scored five; the other ten players to score four goals are Marco van Basten, Simone Inzaghi, Dado Pršo, Ruud van Nistelrooy, Andriy Shevchenko, Bafétimbi Gomis, Mario Gómez, Zlatan Ibrahimović, Cristiano Ronaldo and Serge Gnabry. Messi and Ronaldo have scored three or more goals eight times in the Champions League, more than any other player, followed by Lewandowski, Filippo Inzaghi, Gómez and Luiz Adriano, who have done it on three occasions, while Andy Cole, Michael Owen, Samuel Eto'o, Marco Simone, Van Nistelrooy, Roy Makaay, Roberto Soldado, Didier Drogba, Shevchenko, Sergio Agüero, Karim Benzema and Neymar have scored two hat-tricks.

Only Ronaldo and Messi have scored three or more goals on more than a single occasion in the knock-out round. Eleven of the players have each scored hat-tricks for two or more different clubs: Inzaghi, Eto'o, Van Nistelrooy, Shevchenko, Lewandowski and Ronaldo. Nine players have scored a hat-trick on their debut in the Champions League: Van Basten, Faustino Asprilla, Wayne Rooney, Vincenzo Iaquinta, Yacine Brahimi, Erling Braut Håland and Mislav Oršić. Six players have scored hat-tricks in two consecutive seasons: Adriano, Gómez, Cristiano Ronaldo and Gabriel Jesus. Two players have achieved hat-tricks in back-to-back games. Cristiano Ronaldo did it for Real Madrid against Bayern Munich on 18 April 2017 and Atlético Madrid on 2 May 2017, the shortest gap at just 14 days, Luiz Adriano did it for Shakhtar Donetsk against BATE Borisov on 21 October and 5 November 2014, a gap of 15 days; the longest spell between two hat-tricks was achieved by Owen, who scored his first hat-trick on 22 October 2002 for Liverpool and his second over seven years on 8 December 2009 for Manchester United.

Cristiano Ronaldo is the only player to score more than two hat-tricks in the same season, having scored three goals for Real Madrid on 15 September 2015, four on 8 December 2015, another three on 12 April 2016. Two other players have scored hat-tricks in the same season: Messi scored two for Barcelona in two separate seasons, the first on 1 November 2011 and the second on 7 March 2012, repeating the feat with hat-tricks on 13 September 2016 and 19 October 2016, Gómez scored a hat-trick for Bayern Munich on 2 November 2011 and another four goals on 13 March 2012. Bafétimbi Gomis holds the record for the quickest Champions League hat-trick, netting three times for French team Olympique Lyonnais against Croatian team Dinamo Zagreb in 7 minutes on 7 December 2011; the record was held for 16 years by Mike Newell, who scored a perfect hat-trick for English team Blackburn Rovers against Norwegian team Rosenborg on 6 December 1995 in 9 minutes. The youngest scorer of a Champions League hat-trick was Raúl, who scored a hat-trick for Real Madrid against Ferencváros, aged 18 years and 114 days, on 18 October 1995.

Wayne Rooney is the youngest debut scorer of a Champions League hat-trick, aged 18 years and 340 days, when he scored for Manchester United against Fenerbahçe on 28 September 2004. The oldest scorer of a hat-trick in the UEFA Champions League is Cristiano Ronaldo, 34 years and 35 days old when he scored for Juventus three times against Atlético Madrid on 12 March 2019; the seasons with the most hat-tricks were 2019 -- 20, each of which had nine. As of 11 December 2019 The following table lists the number of 4-goals scored by players who have scored two or more 4-goals. Boldface indicates a player, active; the following table lists the number of hat-tricks scored by players who have scored two or more hat-tricks. Boldface indicates a player, active. UEFA Champions League List of European Cup and UEFA Champions League top scorers

Wear leveling

Wear leveling is a technique for prolonging the service life of some kinds of erasable computer storage media, such as flash memory, used in solid-state drives and USB flash drives, phase-change memory. There are several wear leveling mechanisms that provide varying levels of longevity enhancement in such memory systems; the term preemptive wear leveling has been used by Western Digital to describe their preservation technique used on hard disk drives designed for storing audio and video data. However, HDDs are not wear-leveled devices in the context of this article. EEPROM and flash memory media have individually erasable segments, each of which can be put through a limited number of erase cycles before becoming unreliable; this is around 3,000/5,000 cycles but many flash devices have one block with a specially extended life of 100,000+ cycles that can be used by the Flash memory controller to track wear and movement of data across segments. Erasable optical media such as CD-RW and DVD-RW are rated at up to 1,000 cycles.

Wear leveling attempts to work around these limitations by arranging data so that erasures and re-writes are distributed evenly across the medium. In this way, no single erase block prematurely fails due to a high concentration of write cycles. In flash memory, a single block on the chip is designed for longer life than the others so that the memory controller can store operational data with less chance of its corruption. Conventional file systems such as FAT, UFS, HFS, ext2, NTFS were designed for magnetic disks and as such rewrite many of their data structures to the same area; when these systems are used on flash memory media, this becomes a problem. The problem is aggravated by the fact that some file systems track last-access times, which can lead to file metadata being rewritten in-place. There are three basic types of wear leveling mechanisms used in flash memory storage devices: A flash memory storage system with no wear leveling will not last long if data is written to the flash. Without wear leveling, the underlying flash controller must permanently assign the logical addresses from the operating system to the physical addresses of the flash memory.

This means that every write to a written block must first be read, modified, re-written to the same location. This approach is time-consuming and written locations will wear out while other locations will not be used at all. Once a few blocks reach their end of life, such a device becomes inoperable; the first type of wear leveling is called dynamic wear leveling and it uses a map to link logical block addresses from the OS to the physical flash memory. Each time the OS writes replacement data, the map is updated so the original physical block is marked as invalid data, a new block is linked to that map entry; each time a block of data is re-written to the flash memory, it is written to a new location. However, flash memory blocks that never get replacement data would sustain no additional wear, thus the name comes only from the dynamic data being recycled; such a device may last longer than one with no wear leveling, but there are blocks still remaining as active though the device is no longer operable.

The other type of wear leveling is called static wear leveling which uses a map to link the LBA to physical memory addresses. Static wear leveling works the same as dynamic wear leveling except the static blocks that do not change are periodically moved so that these low usage cells are able to be used by other data; this rotational effect enables an SSD to continue to operate until most of the blocks are near their end of life. Both dynamic and static wear leveling are implemented at the local level; this means that in a multi-chip product, every chip is managed as a single resource. The number of defective blocks in different chips within a NAND flash memory varies. A given chip can have all its data blocks worn out while another one can have all the blocks still active. To salvage this situation, global wear leveling is introduced. In global wear leveling, all blocks in all flash chips in the flash memory are managed together in a single pool, it ensures. The following table compares static and dynamic wear leveling: There are several techniques for extending the media life: A checksum or error-correcting code can be kept for each block or sector in order to detect errors or correct errors.

A pool of reserve space can be kept. When a block or sector does fail, future reads and writes to it can be redirected to a replacement in that pool. Blocks or sectors on the media can be tracked in a least used queue of some sort; the data structures for the queue itself must either be stored off-device or in such a way that the space it uses is itself wear-leveled or, in the case of flash memory, in a block with a specially extended life. However, usual cache algorithms are designed to manage the data flow into and out of RAM-based caches, making them not directly suitable for flash-based storage devices as they have an asymmetrical nature – reads are much faster than writes, erase operations can be performed only one "block" at a time. On some specialist Secure Digital cards, techniques are implemented in hardware by a built-in microcontroller. On such devices, wear leveling is transparent, most conventional file systems can be used on them as-is. Wear leveling can be implemented in software by special-purpose file systems such as JFFS2 and YAFFS on flash media or UDF on optical media.

All three are log-structured file systems in that they tre