The Editors are an English rock band, formed in 2002 in Birmingham. Known as Pilot, The Pride and Snowfield, the band consists of Tom Smith, Russell Leetch, Ed Lay, Justin Lockey, Elliott Williams; the Editors have so far released two platinum studio albums, six in total, with several million combined sales. Their debut album The Back Room was released in 2005, it contained the hits "Munich" and "Blood" and the following year received a Mercury Prize nomination. Their follow-up album An End Has a Start went to number 1 in the UK Album Chart in June 2007 and earned the band a Brit Awards nomination for best British Band, it spawned another Top 10 hit single, "Smokers Outside the Hospital Doors". The band's third album, In This Light and on This Evening, was released in October 2009 and went straight to number 1 in the UK Album Chart; the band released their fourth studio album, The Weight of Your Love, in July 2013, followed by self-produced In Dream in October 2015. In 2018, the band released their sixth album Violence.
Alongside their critical acclaim and strong success in the charts, Editors have enjoyed sold-out tours and numerous headlining festival slots. Their brand of dark indie rock is compared to the sound of bands such as Echo & the Bunnymen, Joy Division, The Chameleons and U2, their music was featured throughout the Twilight saga movies. The band met while studying Music Technology at Staffordshire University, but living in Birmingham and playing at venues such as the Jug of Ale and the Flapper & Firkin, the former of which bands such as Oasis and Blur played in during their primitive years, helped the band obtain a record deal. In an interview in 2015, Tom Smith said, "Birmingham is important. Looking back further it was where we all lived together in the early years, played all those Flapper and Jug of Ale shows, got our record deal. We've always said although only one of us was brought up there, Birmingham was the band's home"; the band was known as Pilot and played its first show under this name in 2002.
While in college, the band constructed a marketing strategy which involved placing hundreds of promotional stickers across the walls of Stafford asking "Who's the Pilot?". However, they realised the name was taken by a 1970s Scottish pop group, so they changed their name to The Pride, they made a promo under this name with the tracks "Come Share the View" and "Forest Fire" and uploaded them onto the internet, making the songs available to listen to on BBC Radio 1's Onemusic Unsigned. A review of the songs reads "The Pride keep things subliminally lo-fi. Refreshingly simple and restrained, "Come Share The View" is a lesson in welding hypnotic soundscapes with white noise while showing allegiance to the school of slo-mo on "Forest Fire""; the band took its music offline to create mystery and anxiousness and ensure that more "A&R" representatives came to see them perform. They changed the line-up with Ed Lay replacing Geraint Owen on drums as he began to focus on his Welsh band The Heights. Under this lineup they became known as Snowfield.
They played their debut gig under this name at the request of Fused Magazine in March 2003. The following summer the band self-released a demo six-track EP, all of which went on to become future Editors songs; as it was the home of their management and the nearest big city, the band relocated to Birmingham after graduation in the autumn of 2003. For the next year, the different band members worked part-time jobs along with the rest of their work with the band. After continuous gigging around the Midlands, it wasn't long until word of mouth helped them become a popular unsigned band; the band sent out a one track demo cd of Bullets, earning them the interest of several British labels, with thirty A&R reps coming to see them play at Birmingham. In October 2004, the group signed to Newcastle based indie label Kitchenware Records. Upon signing to the record label they changed their band name to Editors. After supporting bands such as Puressence and Oceansize, Editors released debut single "Bullets" recorded with producer Gavin Monaghan as a limited edition of 1000 copies on Kitchenware Records on 24 January 2005.
The song had been played by BBC Radio 1 disc jockey Zane Lowe, where it earned the honour of'Single of the Week'. The limited run sold out on the day of its release, with copies famously sold in the week for more than £30 on eBay; the release of "Munich" followed in April of that year and gave the band their first Top 25 hit, another sold out UK tour and a place on MTV’s Spanking New Music show in Manchester. At this point, due to the band's increasing popularity and Kitchenware signed an exclusive distribution deal with Sony BMG. "Blood" was released two months reaching number 18 in the UK Singles Chart in its first week, selling 5,286 copies. With these releases their fanbase continued to grow and on 25 July 2005 their debut album The Back Room was released to critical acclaim and commercial success. In its first week, the album entered the charts at number 13. After re-issuing "Bullets" and achieving another Top 30 hit, Editors gained a high-profile support slot, supporting Franz Ferdinand in arenas across the UK and Europe.
Editors re-issued "Munich" in January 2006, selling one and half thousand more copies than the last time it was released. The song gave Editors an appearance on Top of the Pops. With the single release, The Back Room rose back up the album charts, peaking at number 2, it sold an additional 40,000 copies in the week
Glaciology is the scientific study of glaciers, or more ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, physical geography, climatology, hydrology and ecology; the impact of glaciers on people includes the fields of human anthropology. The discoveries of water ice on the Moon, Mars and Pluto add an extraterrestrial component to the field, referred to as "astroglaciology". A glacier is an extended mass of ice formed from snow falling and accumulating over a long period of time. Areas of study within glaciology include the reconstruction of past glaciation. A glaciologist is a person. A glacial geologist studies glacial deposits and glacial erosive features on the landscape. Glaciology and glacial geology are key areas of polar research. Glaciers can be identified by the relationship to the surrounding topography. There are two general categories of glaciation which glaciologists distinguish: alpine glaciation, accumulations or "rivers of ice" confined to valleys.
Alpine – ice flows down the valleys of mountainous areas and forms a tongue of ice moving towards the plains below. Alpine glaciers tend to make the topography more rugged, by adding and improving the scale of existing features such as large ravines called cirques and ridges where the rims of two cirques meet called arêtes. Continental – an ice sheet found today, only in high latitudes, thousands of square kilometers in area and thousands of meters thick; these tend to smooth out the landscapes. Accumulation, where the formation of ice is faster than its removal. Wastage or ablation, where the sum of melting and evaporation is greater than the amount of snow added each year. Snow line, the area that marks the transition from the accumulation to the ablation zone and vice versa; when a glacier is experiencing an input of precipitation that exceeds the output, the glacier is advancing. Conversely, if the output from evaporation, sublimation and calving exceed the glaciers precipitation input the glacier is receding.
This is referred to as an interglacial period. During periods where ice is advancing at an extreme rate, 100 times faster than what is considered normal, it is referred to as a surging glacier. During times in which the input of precipitation to the glacier is equivalent to the ice lost from calving and melting of the glacier, there is a steady-state condition. Within the glacier, the ice has a downward movement in the accumulation zone and an upwards movement in the ablation zone. Ablation wastage of the glacier through ice melting and iceberg calving. Ablation zone Area of a glacier in which the annual loss of ice through ablation exceeds the annual gain from precipitation. Arête an acute ridge of rock where two cirques meet. Bergschrund crevasse formed near the head of a glacier, where the mass of ice has rotated and torn itself apart in the manner of a geological fault. Cirque, corrie or cwm bowl shaped depression excavated by the source of a glacier. Creep adjustment to stress at a molecular level.
Flow movement in a constant direction. Fracture brittle failure under the stress raised when movement is too rapid to be accommodated by creep, it happens for example. Horn spire of rock known as a pyramidal peak, formed by the headward erosion of three or more cirques around a single mountain, it is an extreme case of an arête. Plucking/Quarrying where the adhesion of the ice to the rock is stronger than the cohesion of the rock, part of the rock leaves with the flowing ice. Tarn a post-glacial lake in a cirque. Tunnel valley The tunnel, formed by hydraulic erosion of ice and rock below an ice sheet margin; the tunnel valley is. Movement of the glacier is slow, its velocity varies from a few centimeters per day to a few meters per day. The rate of movement depends upon the numbers of factors which are listed below: Temperature of the ice Gradient of the slope Thickness of the glacier Subglacial water dynamics Outwash sand/gravel from front of glaciers, found on a plain Kettles block of stagnant ice leaves a depression or pit Eskers steep sided ridges of gravel/sand caused by streams running under stagnant ice Kames stratified drift builds up low steep hills Varves alternating thin sedimentary beds of a proglacial lake.
Summer conditions deposit more and coarser material and those of the winter and finer. Till-unsorted deposited by receding/advancing glaciers, forming moraines, drumlins Moraines material deposited at the end. Drumlins smooth elongated hills composed of till. Ribbed moraines large subglacial elongated hills transverse to former ice flow. International Glaciological Society International Association of Cryospheric Sciences Irish Sea Glacier List of glaciers Cryosphere Benn, Douglas I. and David J. A. Evans. Glaciers and Glaciation. London. ISBN 0-340-58431-9 Greve and Heinz Blatter. Dynamics of Ice Sheets
Geography is a field of science devoted to the study of the lands, features and phenomena of the Earth and planets. The first person to use the word γεωγραφία was Eratosthenes. Geography is an all-encompassing discipline that seeks an understanding of Earth and its human and natural complexities—not where objects are, but how they have changed and come to be. Geography is defined in terms of two branches: human geography and physical geography. Human geography deals with the study of people and their communities, cultures and interactions with the environment by studying their relations with and across space and place. Physical geography deals with the study of processes and patterns in the natural environment like the atmosphere, hydrosphere and geosphere; the four historical traditions in geographical research are: spatial analyses of natural and the human phenomena, area studies of places and regions, studies of human-land relationships, the Earth sciences. Geography has been called "the world discipline" and "the bridge between the human and the physical sciences".
Geography is a systematic study of its features. Traditionally, geography has been associated with place names. Although many geographers are trained in toponymy and cartology, this is not their main preoccupation. Geographers study the space and the temporal database distribution of phenomena and features as well as the interaction of humans and their environment; because space and place affect a variety of topics, such as economics, climate and animals, geography is interdisciplinary. The interdisciplinary nature of the geographical approach depends on an attentiveness to the relationship between physical and human phenomena and its spatial patterns. Names of places...are not geography...know by heart a whole gazetteer full of them would not, in itself, constitute anyone a geographer. Geography has higher aims than this: it seeks to classify phenomena, to compare, to generalize, to ascend from effects to causes, and, in doing so, to trace out the laws of nature and to mark their influences upon man.
This is ` a description of the world' --. In a word Geography is a Science—a thing not of mere names but of argument and reason, of cause and effect. Just as all phenomena exist in time and thus have a history, they exist in space and have a geography. Geography as a discipline can be split broadly into two main subsidiary fields: human geography and physical geography; the former focuses on the built environment and how humans create, view and influence space. The latter examines the natural environment, how organisms, soil and landforms produce and interact; the difference between these approaches led to a third field, environmental geography, which combines physical and human geography and concerns the interactions between the environment and humans. Physical geography focuses on geography as an Earth science, it aims to understand the physical problems and the issues of lithosphere, atmosphere and global flora and fauna patterns. Physical geography can be divided into many broad categories, including: Human geography is a branch of geography that focuses on the study of patterns and processes that shape the human society.
It encompasses the human, cultural and economic aspects. Human geography can be divided into many broad categories, such as: Various approaches to the study of human geography have arisen through time and include: Behavioral geography Feminist geography Culture theory Geosophy Environmental geography is concerned with the description of the spatial interactions between humans and the natural world, it requires an understanding of the traditional aspects of physical and human geography, as well as the ways that human societies conceptualize the environment. Environmental geography has emerged as a bridge between the human and the physical geography, as a result of the increasing specialisation of the two sub-fields. Furthermore, as human relationship with the environment has changed as a result of globalization and technological change, a new approach was needed to understand the changing and dynamic relationship. Examples of areas of research in the environmental geography include: emergency management, environmental management and political ecology.
Geomatics is concerned with the application of computers to the traditional spatial techniques used in cartography and topography. Geomatics emerged from the quantitative revolution in geography in the mid-1950s. Today, geomatics methods include spatial analysis, geographic information systems, remote sensing, global positioning systems. Geomatics has led to a revitalization of some geography departments in Northern America where the subject had a declining status during the 1950s. Regional geography is concerned with the description of the unique characteristics of a particular region such as its natural or human elements; the main aim is to understand, or define the uniqueness, or character of a particular region that consists of natural as well as human elements. Attention is paid to regionalization, which covers the proper techniques of space delimitation into regions. Urban planning, regional planning, spatial planning: Use the science of geography to assist in determining how to develop the land to meet particular criteria, such as safety, economic opportunities, the preservation of the built or natural heritage, so on.
The planning of towns, c
Mount Rainier known as Tahoma or Tacoma, is a large active stratovolcano located 59 miles south-southeast of Seattle, in the Mount Rainier National Park. With a summit elevation of 14,411 ft, it is the highest mountain in the U. S. state of Washington, of the Cascade Range of the Pacific Northwest, it is the second topographically prominent mountain in the continental United States and the first in the Cascade Volcanic Arc. Mt. Rainier is considered one of the most dangerous volcanoes in the world, it is on the Decade Volcano list; because of its large amount of glacial ice, Mt. Rainier could produce massive lahars that could threaten the entire Puyallup River valley. "About 80,000 people and their homes are at risk in Mount Rainier’s lahar-hazard zones." Mount Rainier was first known by Tacoma or Tahoma. One hypothesis of the word origin is, in the Lushootseed language spoken by the Puyallup people. Another hypothesis is that "Tacoma" means "larger than Mount Baker" in Lushootseed: "Ta", plus "Koma", Mount Baker.
Other names used include Tahoma and Pooskaus. The current name was given by George Vancouver, who named it in honor of his friend, Rear Admiral Peter Rainier; the map of the Lewis and Clark expedition of 1804-1806 refers to it as "Mt. Regniere". Although "Rainier" had been considered the official name of the mountain, Theodore Winthrop, in his posthumously published 1862 travel book The Canoe and the Saddle, referred to the mountain as "Tacoma" and for a time, both names were used interchangeably, although "Mt. Tacoma" was preferred in the city of Tacoma. In 1890, the United States Board on Geographic Names declared that the mountain would be known as "Rainier". Following this in 1897, the Pacific Forest Reserve became the Mount Rainier Forest Reserve, the national park was established three years later. Despite this, there was still a movement to change the mountain's name to "Tacoma" and Congress was still considering a resolution to change the name as late as 1924. In the lead-up to Super Bowl XLVIII, the Washington State Senate passed a resolution on Friday, January 31, 2014, temporarily renaming the mountain Mount Seattle Seahawks until the midnight after the Super Bowl, February 3, 2014, in response to the renaming of 53 mountains in Colorado after the 53 members of the Denver Broncos by Governor of Colorado John Hickenlooper.
After the 2015 restoration of the original name Denali from Mount McKinley in Alaska, debate over Mount Rainier's name intensified. Mount Rainier is the tallest mountain in the Cascade Range; this peak is located just southeast of Seattle and Tacoma. Mount Rainier is ranked third of the 128 ultra-prominent mountain peaks of the United States. Mount Rainier has a topographic prominence of 13,210 ft, greater than that of K2, the world's second-tallest mountain, at 13,189 ft. On clear days it dominates the southeastern horizon in most of the Seattle-Tacoma metropolitan area to such an extent that locals sometimes refer to it as "the Mountain." On days of exceptional clarity, it can be seen from as far away as Corvallis and Victoria, British Columbia. With 26 major glaciers and 36 sq mi of permanent snowfields and glaciers, Mount Rainier is the most glaciated peak in the lower 48 states; the summit is topped by two volcanic craters, each more than 1,000 ft in diameter, with the larger east crater overlapping the west crater.
Geothermal heat from the volcano keeps areas of both crater rims free of snow and ice, has formed the world's largest volcanic glacier cave network within the ice-filled craters, with nearly 2 mi of passages. A small crater lake about 130 by 30 ft in size and 16 ft deep, the highest in North America with a surface elevation of 14,203 ft, occupies the lowest portion of the west crater below more than 100 ft of ice and is accessible only via the caves; the Carbon, Mowich and Cowlitz Rivers begin at eponymous glaciers of Mount Rainier. The sources of the White River are Winthrop and Fryingpan Glaciers; the White and Mowich join the Puyallup River, which discharges into Commencement Bay at Tacoma. The broad top of Mount Rainier contains three named summits; the highest is called the Columbia Crest. The second highest summit is Point Success, 14,158 ft, at the southern edge of the summit plateau, atop the ridge known as Success Cleaver, it has a topographic prominence of about 138 ft, so it is not considered a separate peak.
The lowest of the three summits is Liberty Cap, 14,112 ft, at the northwestern edge, which overlooks Liberty Ridge, the Sunset Amphitheater, the dramatic Willis Wall. Liberty Cap has a prominence of 492 ft, so would qualify as a separate peak under most prominence-based rules. A prominence cutoff of 400 ft is used in Washington state. High on the eastern flank of Mount Rainier is a peak known as Little Tahoma Peak, 11,138 ft, an eroded remnant of the earlier, much higher, Mount Rainier, it has a prominence of 858 ft, it is never climbed in direct conjunction with Columbia Crest, so it is considered a separate peak. If considered separately from Mt. Rainier, Little Tahoma Peak would be the third highest mountain peak in Washington. Mount Rainier is a stratovolcano in the Cascade Volcanic Arc that consists of lava flows, debris flows, pyroclastic ejecta and flows, its early volcanic deposits are estimated
A tarn is a mountain lake, pond or pool, formed in a cirque excavated by a glacier. A moraine may form a natural dam below a tarn; the word is derived from the Old Norse word tjörn meaning pond. Its more specific use as a mountain lake emerges as it is the used term for all ponds in the upland areas of Northern England. Here, it retains a broader use, referring to any small lake or pond, regardless of its location and origin. In Scandinavian languages, a tjern or tjärn, tärn or tjørn is a small natural lake in a forest or with vegetation surrounding it or growing into the tarn. Pond Proglacial lake
The climatic snow line is the boundary between a snow-covered and snow-free surface. The actual snow line may adjust seasonally, be either higher in elevation, or lower; the permanent snow line is the level above which snow will lie all year. Snow line is an umbrella term for different interpretations of the boundary between snow-covered surface and snow-free surface; the definitions of the snow line may have different spatial focus. In many regions the changing snow line reflect seasonal dynamics; the final height of the snow line in a mountain environment at the end of the melting season is subject to climatic variability, therefore may be different from year to year. The snow line is measured using aerial photographs, or satellite images; because the snow line can be established without on-the-ground measurements, it can be measured in remote and difficult to access areas. Therefore, the snow line has become an important variable in hydrological models; the average elevation of a transient snow line is called the "climatic snow line" and is used as a parameter to classify regions according to climatic conditions.
The boundary between the accumulation zone and the ablation zone on glaciers is called the "annual snow line". The glacier region below this snow line was subject to melting in the previous season; the term "orographic snow line" is used to describe the snow boundary on surfaces other than glaciers. The term "regional snow line" is used to describe large areas; the "permanent snow line" is the level. The interplay of altitude and latitude affects the precise placement of the snow line at a particular location. At or near the equator, it is situated at 4,500 meters above sea level; as one moves towards the Tropic of Cancer and Tropic of Capricorn, the parameter at first increases: in the Himalayas the permanent snow line can be as high as 5,700 metres, whilst on the Tropic of Capricorn no permanent snow exists at all in the Andes because of the extreme aridity. Beyond the Tropics the snow line becomes progressively lower as the latitude increases, to just below 3,000 metres in the Alps and falling all the way to sea level itself at the ice caps near the poles.
In addition, the relative location to the nearest coastline can influence the altitude of the snow line. Areas near a coast might have a lower snow line than areas of the same altitude and latitude situated in a landmass interior due to more winter snowfall and because the average summer temperature of the surrounding lowlands would be warmer away from the sea.. A higher altitude is therefore necessary to lower the temperature further against the surroundings and keep the snow from melting. Furthermore, large-scale oceanic currents such as the North Atlantic Current can have significant affects over large areas. In the northern hemisphere the snow line on the north facing slopes is at a lower altitude, as the north facing slopes receive less sun light than south facing slopes; the glacier equilibrium line is the point of transition between the accumulation zone and ablation zone. It is the line. Depending on the thickness of the glacier, this line can seem as though it is leaning more towards one zone but it is determined by the actual mass of ice in either zone.
The rates of ablation and accumulation can be used to determine the location of this line. This point is an important location to use in determining whether a glacier is shrinking. A higher glacier equilibrium line will indicate that the glacier is shrinking, whereas a lower line will indicate that the glacier is growing; the terminus of a glacier advances or retreats based on the location of this equilibrium line. Scientists are using remote sensing to better estimate the locations of this line on glaciers around the world. Using satellite imagery, scientists are able to identify whether the glacier is receding; this is a helpful tool for analyzing glaciers that are difficult to access. Using this technology we can better gauge the effects of climate change on glaciers around the world; the highest mountain in the world below the snow line is Ojos del Salado. Compare the usage of "snow line" indicating the boundary between snow and non-snow. Frost line Frost line Glacier High Alps Ice cap climate Tree line Charlesworth J.
K.. The quaternary era. With special reference to its glaciation, vol. I. London, Edward Arnold Ltd, 700 pp. Flint, R. F.. Glacial and Pleistocene geology. John Wiley & Sons, Inc. New York, xiii+553+555 pp. Kalesnik, S. V.. Obshchaya glyatsiologiya. Uchpedgiz, Leningrad, 328 pp. Tronov, M. V.. Voprosy svyazi mezhdu klimatom i oledeneniem. Izdatel'stvo Tomskogo Universiteta, Tomsk, 202 pp. Wilhelm, F.. Schnee- und Gletscherkunde, De Gruyter, Berlin, 414 pp. Braithewaite, R. J. and Raper, S. C. B. "Estimating Equilibrium Line Altitude From Glacier Inventory Data." Annals of Glaciology, 50, pp. 127–132. Doi:10.3189/172756410790595930. Leonard, K. C. and Fountain, A. G.. "Map-Based Methods for Estimating Glacier Equilibrium-Line Altitudes." Journal of Glaciology, vol. 49, no. 166, pp. 329–336. Doi:10.3189/172756503781830665. Ohmura, A. Kasser, P. and Funk, M.. "Climate at the Equilibrium Line
An ice field is a large area of interconnected glaciers found in a mountainous region. They are found in the colder climates and higher altitudes of the world where there is sufficient precipitation for them to form; the higher peaks of the underlying mountain rock that protrude through the icefields are known as nunataks. Ice fields are smaller than ice caps and ice sheets; the topography of ice fields is determined by the shape of the surrounding landforms, while ice caps have their own forms overriding underlying shapes. Ice fields are formed by a large accumulation of snow which, through years of compression and freezing, turns into ice. Due to ice’s susceptibility to gravity, ice fields form over large areas that are basins or atop plateaus, thus allowing a continuum of ice to form over the landscape uninterrupted by glacial channels. Glaciers form on the edges of ice fields, serving as gravity-propelled drains off the ice field, in turn replenished by snowfall. While an ice cap is not constrained by topography, an ice field is.
An ice field is distinguishable from an ice cap because it does not have a dome-like form. There are several ice fields in the Himalayas and Altay Mountains. One unexpected ice field is located in Yolyn Am, a mountain valley located in the northern end of the Gobi Desert. There are no ice fields in Australia. New Zealand has Garden of Eden ice field Garden of Allah ice field Olivine Ice PlateauReference: The only large ice fields in mainland Europe are in Norway. There are several dozen small ice fields in the Alps and tiny remnants of permanent ice in Sweden, the Apennines, the Pyrenees and the Balkans. Since the disappearance of the last remaining ice field in Andalucía, with the disappearance of the Corral del Veleta glacier in 1913, the southernmost surviving permanent ice field in continental Europe is Snezhnika in Bulgaria. Beyond the mainland of continental Europe, there are substantial ice fields in Iceland and Franz-Josef Land and smaller surviving ice fields on Jan Mayen and Novaya Zemlya.
One of the more celebrated North American ice fields is the Columbia Icefield located in the Rocky Mountains between Jasper and Banff, Alberta. Easy access by road contributes to the status of this ice field as one of the most visited in North America, although it is a comparatively small ice field within the huge and ice-free American cordillera. A large number of expansive ice fields lie in the Coast Mountains, Alaska Range, Chugach Mountains of Alaska, British Columbia, the Yukon Territory; the 6,500 km² Stikine Icecap and the 2,500 km² Juneau Icefield both straddle the British Columbian-Alaskan border. Farther north, the Kluane Icecap — which feeds the immense Malaspina and Hubbard Glaciers as well as the Bagley Icefield — sits upon the British Columbia-Yukon Territory-Alaska border and surrounds most of the Saint Elias Mountains as well as both Mount Saint Elias and Mount Logan. There are large ice fields located in the Kenai Peninsula-Chugach Mountains area, such as the Sargent Icefield and the Harding Icefield.
Throughout the Alaska Range there large icefields which are unnamed. In South America, there are two main ice fields, Campo de Hielo Norte, in Chile, Campo de Hielo Sur, shared by Chile and Argentina. There is a small ice field on the western portion of Tierra del Fuego proper. List of glaciers and icefields Ice sheet Glacier Nunatak