Kīlauea

Kīlauea ( -LSB- langˌkiːlaʊˈeɪə -RSB- , also -LSB- ˌkɪləˈweɪə -RSB- ; -LSB- tiːlɐwˈwɛjə -RSB- ) is a currently active shield volcano in the Hawaiian Islands , and the most active of the five volcanoes that together form the island of Hawaii . Located along the southern shore of the island , the volcano is between 300,000 and 600,000 years old and emerged above sea level about 100,000 years ago . It is the second youngest product of the Hawaiian hotspot and the current eruptive center of the Hawaiian -- Emperor seamount chain . Because it lacks topographic prominence and its activities historically coincided with those of Mauna Loa , Kīlauea was once thought to be a satellite of its much larger neighbor . Structurally , Kīlauea has a large , fairly recently formed caldera at its summit and two active rift zones , one extending 125 km east and the other 35 km west , as an active fault of unknown depth moving vertically an average of 2 to per year .   Kīlauea 's eruptive history has been a long and active one ; its name means `` spewing '' or `` much spreading '' in the Hawaiian language , referring to its frequent outpouring of lava . The earliest lavas from the volcano date back to its submarine preshield stage , samples having been recovered by remotely operated underwater vehicles from its submerged slopes ; samples of other flows have been recovered as core samples . Lavas younger than 1,000 years cover 90 percent of the volcano 's surface . The oldest exposed lavas date back 2,800 years . The first well-documented eruption of Kīlauea occurred in 1823 ( Western contact and written history began in 1778 ) , and since that time the volcano has erupted repeatedly . Most historical eruptions have occurred at the volcano 's summit or its eastern rift zone , and are prolonged and effusive in character . The geological record shows , however , that violent explosive activity predating European contact was extremely common , and in 1790 one such eruption killed over 80 warriors ; should explosive activity start anew the volcano would become much more of a danger to humans . Kīlauea 's current eruption dates back to January 3 , 1983 , and is by far its longest-duration historical period of activity , as well as one of the longest-duration eruptions in the world ; as of January 2011 , the eruption has produced 3.5 km3 of lava and resurfaced 123.2 km2 of land .   Kīlauea 's high state of activity has a major impact on its mountainside ecology , where plant growth is often interrupted by fresh tephra and drifting volcanic sulfur dioxide , producing acid rains particularly in a barren area south of its southwestern rift zone known as the Kaʻū Desert . Nonetheless , wildlife flourishes where left undisturbed elsewhere on the volcano and is highly endemic thanks to Kīlauea 's ( and the island of Hawaii 's ) isolation from the nearest landmass . Historically , the five volcanoes on the island were considered sacred by the Hawaiian people , and in Hawaiian mythology Kīlauea 's Halemaumau Crater served as the body and home of Pele , goddess of fire , lightning , wind , and volcanoes . William Ellis , a missionary from England , gave the first modern account of Kīlauea and spent two weeks traveling along the volcano ; since its foundation by Thomas Jaggar in 1912 , the Hawaiian Volcano Observatory , located on the rim of Kīlauea caldera , has served as the principal investigative and scientific body on the volcano and the island in general . In 1916 , a bill forming the Hawaii Volcanoes National Park was signed into law by President Woodrow Wilson ; since then , the park has become a World Heritage Site and a major tourist destination , attracting roughly 2.6 million people annually .


LED lamp

An LED lamp is a light-emitting diode ( LED ) product which is assembled into a lamp ( or light bulb ) for use in lighting fixtures . LED lamps have a lifespan and electrical efficiency which are several times greater than incandescent lamps , and are significantly more efficient than most fluorescent lamps , with some chips able to emit more than 300 lumens per watt ( as claimed by Cree and some other LED manufacturers ) . The LED lamp market is projected to grow by more than twelve-fold over the next decade , from $ 2 billion in the beginning of 2014 to $ 25 billion in 2023 , a compound annual growth rate ( CAGR ) of 25 % . As of 2016 , LEDs use only about 10 % of the energy an incandescent lamp requires .   Like incandescent lamps and unlike most fluorescent lamps ( e.g. tubes and compact fluorescent lamps or CFLs ) , LEDs come to full brightness without need for a warm-up time ; the life of fluorescent lighting is also reduced by frequent switching on and off . The initial cost of LED is usually higher . Degradation of LED dye and packaging materials reduces light output to some extent over time .   Some LED lamps are made to be a directly compatible drop-in replacement for incandescent or fluorescent lamps . An LED lamp packaging may show the lumen output , power consumption in watts , color temperature in kelvins or description ( e.g. `` warm white '' ) , operating temperature range , and sometimes the equivalent wattage of an incandescent lamp of similar luminous output .   Most LEDs do not emit light in all directions , and their directional characteristics affect the design of lamps , although omnidirectional lamps which radiate light over a 360 ° angle are becoming more common . The light output of single LED is less than that of incandescent and compact fluorescent lamps ; in most applications multiple LEDs are used to form a lamp , although high-power versions ( see below ) are becoming available .   LED chips require controlled direct current ( DC ) electrical power and an appropriate circuit as an LED driver is required to convert the alternating current from the power supply to the regulated voltage direct current used by the LEDs . LEDs are adversely affected by high temperature , so LED lamps typically include heat dissipation elements such as heat sinks and cooling fins .   LED drivers are the essential components of LED lamps or luminaries . A good LED driver can guarantee a long life for an LED system and provide additional features such as dimming and control . The LED drivers can be put inside lamp or luminaire , which is called a built-in type , or be put outside , which is called an independent type . According to different applications , different types of LED drivers need to be applied , for example an outdoor driver for street light , an indoor point driver for a down light , and an indoor linear driver for a panel light .


La Niña

La Niña ( -LSB- lɑːˈniːnjə -RSB- , -LSB- la ˈniɲa -RSB- ) is a coupled ocean-atmosphere phenomenon that is the counterpart of El Niño as part of the broader El Niño -- Southern Oscillation climate pattern . The name La Niña originates from Spanish , meaning `` the little girl '' , analogous to El Niño meaning `` the little boy '' . It has also in the past been called anti-El Niño , and El Viejo ( meaning `` the old man '' ) . During a period of La Niña , the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 3 to 5 ° C . In the United States , an appearance of La Niña persists for at least five months . It has extensive effects on the weather in North America , even affecting the Atlantic Hurricane Season .


Lake

A lake is an area of variable size filled with water , localized in a basin , that is surrounded by land , apart from any river or other outlet that serves to feed or drain the lake . Lakes lie on land and are not part of the ocean , and therefore are distinct from lagoons , and are also larger and deeper than ponds , though there are no official or scientific definitions . Lakes can be contrasted with rivers or streams , which are usually flowing . Most lakes are fed and drained by rivers and streams .   Natural lakes are generally found in mountainous areas , rift zones , and areas with ongoing glaciation . Other lakes are found in endorheic basins or along the courses of mature rivers . In some parts of the world there are many lakes because of chaotic drainage patterns left over from the last Ice Age . All lakes are temporary over geologic time scales , as they will slowly fill in with sediments or spill out of the basin containing them .   Many lakes are artificial and are constructed for industrial or agricultural use , for hydro-electric power generation or domestic water supply , or for aesthetic or recreational purposes or even for other activities .


Lake Erie

Lake Erie ( -LSB- ˈɪəri -RSB- Lac Érié ) is the fourth-largest lake ( by surface area ) of the five Great Lakes in North America , and the thirteenth-largest globally if measured in terms of surface area . It is the southernmost , shallowest , and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time . At its deepest point Lake Erie is 210 ft deep . Lake Erie 's northern shore is bounded by the Canadian province of Ontario , with the U.S. states of Ohio , Pennsylvania , and New York on its southern and easternmost shores and the Lower Peninsula of Michigan on the west . These jurisdictions divide the surface area of the lake by water boundaries . The lake was named by the Erie people , a Native Americans people who lived along its southern shore . That Iroquoian tribe called it `` Erige '' ( `` cat '' ) because of its unpredictable and sometimes violently dangerous nature . It is a matter of conjecture whether the lake was named after the tribe , or if the tribe was called `` Erie '' because of its proximity to the lake .   Situated below Lake Huron , Erie 's primary inlet is the Detroit River . The main natural outflow from the lake is via the Niagara River , which provides hydroelectric power to Canada and the U.S. as it spins huge turbines near Niagara Falls at Lewiston , New York and Queenston , Ontario . Some outflow occurs via the Welland Canal which diverts water for ship passages from Port Colborne , Ontario on Lake Erie , to St. Catharines on Lake Ontario , an elevation difference of 326 ft. Lake Erie 's environmental health has been an ongoing concern for decades , with issues such as overfishing , pollution , algae blooms and eutrophication generating headlines .


Lake Superior

Lake Superior ( Lac Supérieur ) is the largest of the Great Lakes of North America . The lake is shared by the Canadian province of Ontario to the north , the US state of Minnesota to the west , and Wisconsin and the Upper Peninsula of Michigan to the south . It is generally considered the largest freshwater lake in the world by surface area . It is the world 's third-largest freshwater lake by volume and the largest by volume in North America .


Lake Tahoe

Lake Tahoe ( -LSB- ˈtɑːhoʊ -RSB- ) is a large freshwater lake in the Sierra Nevada of the United States . Lying at 6225 ft , it straddles the border between California and Nevada , west of Carson City . Lake Tahoe is the largest alpine lake in North America , and at 122160280 acre.ft trails only the five Great Lakes as the largest by volume in the United States . Its depth is 1645 ft , making it the second deepest in the United States after Crater Lake in Oregon ( 1945 ft ) .   The lake was formed about 2 million years ago as part of the Lake Tahoe Basin , with the modern extent being shaped during the ice ages . It is known for the clarity of its water and the panorama of surrounding mountains on all sides . The area surrounding the lake is also referred to as Lake Tahoe , or simply Tahoe . More than 75 % of the lake 's watershed is national forest land , comprising the Lake Tahoe Basin Management Unit of the United States Forest Service .   Lake Tahoe is a major tourist attraction in both Nevada and California . It is home to winter sports , summer outdoor recreation , and scenery enjoyed throughout the year . Snow and ski resorts are a significant part of the area 's economy and reputation . The Nevada side also offers large casinos , with highways providing year-round access to the entire area .


Lake Vostok

Lake Vostok ( Озеро Восток , Ozero Vostok , lit . `` Lake East '' ) is the largest of Antarctica 's almost 400 known subglacial lakes .  Lake Vostok is located at the southern Pole of Cold , beneath Russia 's Vostok Station under the surface of the central East Antarctic Ice Sheet , which is at 3488 m above mean sea level . The surface of this fresh water lake is approximately 4000 m under the surface of the ice , which places it at approximately 500 m below sea level .   Measuring 250 km long by 50 km wide at its widest point , and covering an area of 12500 km2 and an average depth of 432 m , it has an estimated volume of 5400 km3 . The lake is divided into two deep basins by a ridge . The liquid water over the ridge is about 200 m , compared to roughly 400 m deep in the northern basin and 800 m deep in the southern .   The lake is named after Vostok Station , which in turn is named after the Vostok , a sloop-of-war ship , which means `` East '' in Russian . The existence of a subglacial lake in the Vostok region was first suggested by Russian geographer Andrey Kapitsa based on seismic soundings made during the Soviet Antarctic Expeditions in 1959 and 1964 to measure the thickness of the ice sheet . The continued research by Russian and British scientists led by 1993 to the final confirmation of the existence of the lake by J. P. Ridley using ERS-1 laser altimetry .   The overlying ice provides a continuous paleoclimatic record of 400,000 years , although the lake water itself may have been isolated for 15 to 25 million years . On 5 February 2012 , a team of Russian scientists completed the longest ever ice core of 3768 m and pierced the ice shield to the surface of the lake .   The first core of freshly frozen lake ice was obtained on 10 January 2013 at a depth of 3406 m. However , as soon as the ice was pierced , water from the underlying lake gushed up the borehole , mixing it with the Freon and kerosene used to keep the borehole from freezing . A new borehole was drilled and an allegedly pristine water sample was obtained in January 2015 . The Russian team plans to eventually lower a probe into the lake to collect water samples and sediments from the bottom . It is hypothesized that unusual forms of life could be found in the lake 's liquid layer , a fossil water reserve . Lake Vostok contains an environment sealed off below the ice for millions of years , in conditions which could resemble those of the ice-covered ocean of Jupiter 's moon Europa , and Saturn 's moon Enceladus .


Lake Worth Beach, Florida

Lake Worth Beach, previously named Lake Worth, is a city in Palm Beach County, Florida, United States, located about 64 miles north of Miami, its name from the body of water along its eastern border known as the Lake Worth Lagoon. The lake itself was named for General William J. Worth, who led U.S. forces during the last part of the Second Seminole War. As of 2010, the population estimated by the U.S. Census Bureau was 34,910. It is a principal city of the Miami metropolitan area, which was home to an estimated 6,012,331 people in 2015.


Lake ecosystem

A lake ecosystem includes biotic ( living ) plants , animals and micro-organisms , as well as abiotic ( nonliving ) physical and chemical interactions .   Lake ecosystems are a prime example of lentic ecosystems . Lentic refers to stationary or relatively still water , from the Latin lentus , which means sluggish . Lentic waters range from ponds to lakes to wetlands , and much of this article applies to lentic ecosystems in general . Lentic ecosystems can be compared with lotic ecosystems , which involve flowing terrestrial waters such as rivers and streams . Together , these two fields form the more general study area of freshwater or aquatic ecology .   Lentic systems are diverse , ranging from a small , temporary rainwater pool a few inches deep to Lake Baikal , which has a maximum depth of 1740 m . The general distinction between pools/ponds and lakes is vague , but Brown states that ponds and pools have their entire bottom surfaces exposed to light , while lakes do not . In addition , some lakes become seasonally stratified ( discussed in more detail below . ) Ponds and pools have two regions : the pelagic open water zone , and the benthic zone , which comprises the bottom and shore regions . Since lakes have deep bottom regions not exposed to light , these systems have an additional zone , the profundal . These three areas can have very different abiotic conditions and , hence , host species that are specifically adapted to live there .


Lakes on Mars

In summer 1965 , the first close-up pictures from Mars showed a cratered desert with no signs of water . However , over the decades , as more parts of the planet were imaged with better cameras on more sophisticated satellites , Mars showed evidence of past river valleys , lakes , and ice in glaciers and in the ground . It was discovered that the climate of Mars displays huge changes over geologic time because its axis is not stabilized by a large moon , as Earth 's is . Also , some researchers maintain that water could exist for periods of time due to geothermal effects or asteroid impacts .   Besides seeing features that were signs of past water , researchers found other types of evidence for past water . Minerals detected in many locations needed water to form . An instrument in the Mars Odyssey , an orbiting spacecraft , mapped the distribution of water in the near surface . When the Phoenix spacecraft fired its rockets to land in the far north , ice was exposed .   When water enters a large body of water , such as a lake , a delta may form . Many craters and other depressions on Mars show deltas that resemble those on Earth . In addition , if a lake lies in a depression , channels entering it will all stop at the same altitude . Such an arrangement is visible around places on Mars that are supposed to have contained large bodies of water -- including around a possible ocean in the North .   Lake formation has been proposed by various researchers for quite some time . One study found 205 possible closed-basin lakes in craters on Mars . The basins have an inlet valley that cuts the crater rim and flows into the basin , but they have no visible outlet valley . The total volume of the basins is equivalent to a depth of 1.2 meters spread evenly over the Martian surface . However , this amount is a small fraction of the current water ice stores on Mars . Another study found 210 open-basin lakes . These were lakes with both an inlet and an outlet ; hence water must have entered the basin , and reached the height of the outlet . Some of these lakes had volumes similar to Earth 's Caspian Sea , Black Sea , and Lake Baikal .   Moreover , some basins on Mars form part of long chains of lakes . The Naktong/Scamander/Mamers Valles lake-chain system is about 4500 km ( 2800 miles ) long , with a drainage area similar to that of the Missouri-Mississippi rivers . Another , the Samara/Himera Vallis system , is 1800 km long . Many of the long chains of lakes are found in the Margaritifer Sinus quadrangle .   Some of the lakes appear to have had a high volume as compared to their drainage area ; hence , it is believed that some of the water was groundwater . Further evidence is the existence of knobby material on the basin floors . These knobs can be formed when large amounts of water left the ground .   This article describes some of the places that could have held large lakes .


Lamont–Doherty Earth Observatory

The Lamont -- Doherty Earth Observatory ( LDEO ) is a research unit of Columbia University located on a 157 acre campus in Palisades , N.Y. , 18 mi north of Manhattan on the Hudson River .


Land degradation

Land degradation is a process in which the value of the biophysical environment is affected by a combination of human-induced processes acting upon the land .  It is viewed as any change or disturbance to the land perceived to be deleterious or undesirable . Natural hazards are excluded as a cause ; however human activities can indirectly affect phenomena such as floods and bush fires .   This is considered to be an important topic of the 21st century due to the implications land degradation has upon agronomic productivity , the environment , and its effects on food security . It is estimated that up to 40 % of the world 's agricultural land is seriously degraded .


Larsen Ice Shelf

The Larsen Ice Shelf is a long , fringing ice shelf in the northwest part of the Weddell Sea , extending along the east coast of the Antarctic Peninsula from Cape Longing to the area just southward of Hearst Island . It is named for Captain Carl Anton Larsen , the master of the Norwegian whaling vessel Jason , who sailed along the ice front as far as 68 ° 10 ' South during December 1893 . In finer detail , the Larsen Ice Shelf is a series of shelves that occupy ( or occupied ) distinct embayments along the coast . From north to south , the segments are called Larsen A ( the smallest ) , Larsen B , and Larsen C ( the largest ) by researchers who work in the area . Further south , Larsen D and the much smaller Larsen E , F and G are also named .   The breakup of the ice shelf since the mid 1990s has been widely reported , with the collapse of Larsen B in 2002 being particularly dramatic .


Last Glacial Period

The Last Glacial Period (LGP) occurred from the end of the Eemian to the end of the Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago. The LGP is part of a larger sequence of glacial and interglacial periods known as the Quaternary glaciation which started around 2,588,000 years ago and is ongoing.  The definition of the Quaternary as beginning 2.58 million years ago is based on the formation of the Arctic ice cap. The Antarctic ice sheet began to form earlier, at about 34 Ma, in the mid-Cenozoic (Eocene–Oligocene extinction event). The term Late Cenozoic Ice Age is used to include this early phase.During this last glacial period there were alternating episodes of glacier advance and retreat. Within the last glacial period the Last Glacial Maximum was approximately 22,000 years ago. While the general pattern of global cooling and glacier advance was similar, local differences in the development of glacier advance and retreat make it difficult to compare the details from continent to continent (see picture of ice core data below for differences). Approximately 12,800 years ago, the Younger Dryas, the most recent glacial epoch, began, a coda to the preceding 100,000 year glacial period. Its end about 11,550 years ago marked the beginning of the Holocene, the current geological epoch. From the point of view of human archaeology, the last glacial period falls in the Paleolithic and early Mesolithic periods. When the glaciation event started, Homo sapiens were confined to lower latitudes and used tools comparable to those used by Neanderthals in western and central Eurasia and by Denisovans and Homo erectus in Asia. Near the end of the event, Homo sapiens migrated into Eurasia and Australia. Archaeological and genetic data suggest that the source populations of Paleolithic humans survived the last glacial period in sparsely wooded areas and dispersed through areas of high primary productivity while avoiding dense forest cover.


Latvia

Latvia ( -LSB- ˈlætviə -RSB- Latvija -LSB- ˈlatvija -RSB- ) , officially the Republic of Latvia ( -LSB- Latvijas Republika , links = no -RSB- ) , is a country in the Baltic region of Northern Europe , one of the three Baltic states . It is bordered by Estonia to the north , Lithuania to the south , Russia to the east , and Belarus to the southeast , as well as a maritime border to the west alongside Sweden . Latvia has 1,957,200 inhabitants and a territory of 64589 km2 . The country has a temperate seasonal climate .   Latvia is a democratic parliamentary republic established in 1918 . The capital city is Riga , the European Capital of Culture 2014 . Latvian is the official language . Latvia is a unitary state , divided into 119 administrative divisions , of which 110 are municipalities and 9 are cities .   Latvians and Livs are the indigenous people of Latvia . Latvian and Lithuanian are the only two surviving Baltic languages . Despite foreign rule from the 13th to 20th centuries , the Latvian nation maintained its identity throughout the generations via the language and musical traditions . Latvia and Estonia share a long common history . As a consequence of centuries of Russian rule ( 1710-1918 ) and later Soviet occupation , both countries are home to a large number of ethnic Russians ( 26.9 % in Latvia and 25.5 % in Estonia ) , some of whom ( 14.1 % of Latvian residents ) have not gained citizenship , leaving them with no citizenship at all . Until World War II , Latvia also had significant minorities of ethnic Germans and Jews .   Latvia is historically predominantly Protestant Lutheran , except for the Latgale region in the southeast , which has historically been predominantly Roman Catholic . The Russian population has also brought a significant portion of Eastern Orthodox Christians .   The Republic of Latvia was founded on 18 November 1918 . However , its de facto independence was interrupted at the outset of World War II . In 1940 , the country was forcibly incorporated into the Soviet Union , invaded and occupied by Nazi Germany in 1941 , and re-occupied by the Soviets in 1944 to form the Latvian SSR for the next fifty years . The peaceful Singing Revolution , starting in 1987 , called for Baltic emancipation of Soviet rule . It ended with the Declaration on the Restoration of Independence of the Republic of Latvia on 4 May 1990 , and restoring de facto independence on 21 August 1991 .   Latvia is a democratic and developed country and member of the European Union , NATO , the Council of Europe , the United Nations , CBSS , the IMF , NB8 , NIB , OECD , OSCE , and WTO . For 2014 , Latvia was listed 46th on the Human Development Index and as a high income country on 1 July 2014 . It used the Latvian lats as its currency until it was replaced by the euro on 1 January 2014 .


Lava

Lava is the molten rock expelled by a volcano during an eruption . The resulting rock after solidification and cooling is also called lava . The molten rock is formed in the interior of some planets , including Earth , and some of their satellites . The source of the heat that melts the rock within the earth is geothermal energy . When first erupted from a volcanic vent , lava is a liquid usually at temperatures from 700 to .   A lava flow is a moving outpouring of lava , which is created during a non-explosive effusive eruption . When it has stopped moving , lava solidifies to form igneous rock . The term lava flow is commonly shortened to lava . Although lava can be up to 100,000 times more viscous than water , lava can flow great distances before cooling and solidifying because of its thixotropic and shear thinning properties .   Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra , rather than lava flows . The word lava comes from Italian , and is probably derived from the Latin word labes which means a fall or slide . The first use in connection with extruded magma ( molten rock below the Earth 's surface ) was apparently in a short account written by Francesco Serao on the eruption of Vesuvius between May 14 and June 4 , 1737 . Serao described `` a flow of fiery lava '' as an analogy to the flow of water and mud down the flanks of the volcano following heavy rain .


Leap year

A leap year ( also known as an intercalary year or bissextile year ) is a calendar year containing one additional day ( or , in the case of lunisolar calendars , a month ) added to keep the calendar year synchronized with the astronomical or seasonal year . Because seasons and astronomical events do not repeat in a whole number of days , calendars that have the same number of days in each year drift over time with respect to the event that the year is supposed to track . By inserting ( also called intercalating ) an additional day or month into the year , the drift can be corrected . A year that is not a leap year is called a common year .   For example , in the Gregorian calendar , each leap year has 366 days instead of the usual 365 , by extending February to 29 days rather than the common 28 . Similarly , in the lunisolar Hebrew calendar , Adar Aleph , a 13th lunar month , is added seven times every 19 years to the twelve lunar months in its common years to keep its calendar year from drifting through the seasons . In the Baha'i Calendar , a leap day is added when needed to ensure that the following year begins on the vernal equinox .   The name `` leap year '' probably comes from the fact that while a fixed date in the Gregorian calendar normally advances one day of the week from one year to the next , the day of the week in the 12 months following the leap day ( from March 1 through February 28 of the following year ) will advance two days due to the extra day ( thus `` leaping over '' one of the days in the week ) . For example , Christmas Day fell on a Tuesday in 2001 , Wednesday in 2002 , and Thursday in 2003 but then `` leapt '' over Friday to fall on a Saturday in 2004 .   The length of a day is also occasionally changed by the insertion of leap seconds into Coordinated Universal Time ( UTC ) , owing to the variability of Earth 's rotational period . Unlike leap days , leap seconds are not introduced on a regular schedule , since the variability in the length of the day is not entirely predictable .


Legendre symbol

In number theory , the Legendre symbol is a multiplicative function with values 1 , − 1 , 0 that is a quadratic character modulo an odd prime number p : its value on a ( nonzero ) quadratic residue mod p is 1 and on a non-quadratic residue ( non-residue ) is − 1 . Its value on zero is 0 .   The Legendre symbol was introduced by Adrien-Marie Legendre in 1798 in the course of his attempts at proving the law of quadratic reciprocity . Generalizations of the symbol include the Jacobi symbol and Dirichlet characters of higher order . The notational convenience of the Legendre symbol inspired introduction of several other `` symbols '' used in algebraic number theory , such as the Hilbert symbol and the Artin symbol .


Leonid Hurwicz

Leonid `` Leo '' Hurwicz ( August 21 , 1917 -- June 24 , 2008 ) was a Polish American economist and mathematician . He originated incentive compatibility and mechanism design , which show how desired outcomes are achieved in economics , social science and political science . Hurwicz shared the 2007 Nobel Memorial Prize in Economic Sciences ( with Eric Maskin and Roger Myerson ) for work on mechanism design . To date , Leonid Hurwicz is the oldest Nobel Laureate , having received the prize at the age of 90 .   Hurwicz was educated and grew up in Poland , and became a refugee in the United States after Hitler invaded Poland in 1939 . In 1941 , Hurwicz worked as a research assistant for Paul Samuelson at the Massachusetts Institute of Technology and Oskar Lange at the University of Chicago . He was a research associate for the Cowles Commission between 1942 and 1946 . In 1946 he became an associate professor of economics at Iowa State College . Hurwicz joined the University of Minnesota in 1951 , becoming Curtis L. Carlson Regents Professor of Economics in 1989 . He was Regents ' Professor of Economics ( Emeritus ) at the University of Minnesota when he died in 2008 .   Hurwicz was among the first economists to recognize the value of game theory and was a pioneer in its application . Interactions of individuals and institutions , markets and trade are analyzed and understood today using the models Hurwicz developed .


Level Mountain

Level Mountain is an immense volcanic massif in the Northern Interior of British Columbia , Canada . It is north-northwest of Telegraph Creek and west of Dease Lake on the Nahlin Plateau . With a maximum elevation of , it is the third highest of five large volcanic complexes in the Northern Cordilleran Volcanic Province ( NCVP ) . Much of the massif is gently-sloping ; when measured from its base , Level Mountain is about tall , slightly taller than its neighbour to the northwest , Heart Peaks . The lower broader half of Level Mountain consists of a shield-like edifice while its upper half has a more steep , jagged profile . Its summit is dominated by the Level Mountain Range , a small mountain range with prominent peaks cut by deep valleys . These valleys serve as a radial drainage for several small streams that flow across the volcano . Meszah Peak is the only named peak in the Level Mountain Range .   The massif is about 15 million years old , with volcanism continuing up until geologically recent times . Three constructive stages have been identified at Level Mountain . The first stage commenced 14.9 million years ago with the eruption of voluminous lava flows . These lavas assembled to create a large shield volcano . The second stage began 7.1 million years ago to form a complex stratovolcano located centrally atop the shield . A series of lava domes were established during the third stage , which started 4.5 million years ago . Renewed activity might have occurred in the last 11,000 years . A wide range of rock types were produced during the long volcanic history of Level Mountain , of which alkali basalts and ankaramites are the most common . They were deposited by different types of volcanic eruptions characterized by passive lava flows and explosivity .   Level Mountain can be ecologically divided into three sections : an alpine climate at its summit , a largely destroyed Abies lasiocarpa forest on its flanks and a Picea glauca forest at its base . An extensive wild animal community once thrived in the area of Level Mountain . This included a wide range of animal species with caribou being the most abundant . Humans had arrived at Level Mountain by the early 1900s , followed by geological studies of the massif in the 1920s . This remote area of Cassiar Land District has a relatively dry environment compared to the Coast Mountains in the west .


Limestone

Limestone is a sedimentary rock , composed mainly of skeletal fragments of marine organisms such as coral , forams and molluscs . Its major materials are the minerals calcite and aragonite , which are different crystal forms of calcium carbonate ( CaCO3 ) .   About 10 % of sedimentary rocks are limestones . The solubility of limestone in water and weak acid solutions leads to karst landscapes , in which water erodes the limestone over thousands to millions of years . Most cave systems are through limestone bedrock .   Limestone has numerous uses : as a building material , an essential component of concrete ( Portland cement ) , as aggregate for the base of roads , as white pigment or filler in products such as toothpaste or paints , as a chemical feedstock for the production of lime , as a soil conditioner , or as a popular decorative addition to rock gardens .   The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778 .


Lindsey Graham

Lindsey Olin Graham ( born July 9 , 1955 ) is an American politician and member of the Republican Party who has served as a United States Senator from South Carolina since 2003 .   A native of Central , South Carolina , Graham graduated from the University of South Carolina in 1977 . He received his Juris Doctor from the University of South Carolina School of Law in 1981 . He served in the United States Air Force from 1982 to 1988 and served as a Guardsman first in the South Carolina Air National Guard then in the Air Force Reserves , attaining the rank of colonel . He worked as a lawyer in private practice before he was elected to the South Carolina House of Representatives in 1992 , serving one term from 1993 to 1995 . He then served in the United States House of Representatives , representing South Carolina 's 3rd congressional district from 1995 to 2003 . He was elected to four terms , receiving at least 60 % of the vote each time .   In 2002 , Graham ran for the U.S. Senate after eight-term Republican incumbent Strom Thurmond announced his retirement . Graham won the primary unopposed and defeated Democratic opponent Alex Sanders in the general election . Graham was re-elected to a second term in 2008 , defeating Bob Conley . He won a third term in 2014 , defeating Democrat Brad Hutto and Independent Thomas Ravenel .   Graham is known in the Senate for his advocacy of a strong national defense , his support of the military , and as an advocate of strong United States leadership in world affairs . He is also known for his willingness to be bipartisan and work with Democrats on issues like global warming , tax reform and immigration reform and his belief that judicial nominees should not be opposed solely on their philosophical positions . He is also a critic of the Tea Party movement , arguing for a more inclusive Republican Party .   On May 18 , 2015 , Graham informally announced his candidacy for President of the United States , followed by a formal announcement on June 21 , 2015 , in his hometown of Central , South Carolina . On December 21 , 2015 , he ended his campaign for the presidency . He later endorsed Jeb Bush for President . After Bush suspended his campaign on February 20 , Graham subsequently endorsed Ted Cruz . When it seemed certain that Donald Trump would become the Republican Presidential candidate in early May 2016 , Graham announced he would not vote for Trump .


Liquid

A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a ( nearly ) constant volume independent of pressure . As such , it is one of the four fundamental states of matter ( the others being solid , gas , and plasma ) , and is the only state with a definite volume but no fixed shape . A liquid is made up of tiny vibrating particles of matter , such as atoms , held together by intermolecular bonds . Water is , by far , the most common liquid on Earth . Like a gas , a liquid is able to flow and take the shape of a container . Most liquids resist compression , although others can be compressed . Unlike a gas , a liquid does not disperse to fill every space of a container , and maintains a fairly constant density . A distinctive property of the liquid state is surface tension , leading to wetting phenomena .   The density of a liquid is usually close to that of a solid , and much higher than in a gas . Therefore , liquid and solid are both termed condensed matter . On the other hand , as liquids and gases share the ability to flow , they are both called fluids . Although liquid water is abundant on Earth , this state of matter is actually the least common in the known universe , because liquids require a relatively narrow temperature/pressure range to exist . Most known matter in the universe is in gaseous form ( with traces of detectable solid matter ) as interstellar clouds or in plasma form within stars .


Lisa P. Jackson

Lisa Perez Jackson ( born February 8 , 1962 ) is an American chemical engineer who served as the Administrator of the United States Environmental Protection Agency ( EPA ) from 2009 to 2013 . In May 2013 , it was announced that Jackson would be joining Apple Inc. as their environmental director .   Born in Philadelphia , Pennsylvania , Jackson is a graduate of Tulane University and Princeton University . She began working as a staff-level engineer for the Environmental Protection Agency in 1987 ; later moving to the EPA 's regional office in New York City , where she spent the majority of her 16-year EPA career . She joined the New Jersey Department of Environmental Protection in 2002 , working as the assistant commissioner of compliance and enforcement and as the assistant commissioner for land use management . In 2006 , New Jersey Governor Jon Corzine appointed Jackson the state 's Commissioner of Environmental Protection . Jackson also briefly served as Corzine 's Chief of Staff in late 2008 .   On December 15 , 2008 , the President-elect Barack Obama nominated Jackson as the Administrator of the Environmental Protection Agency , she was confirmed by the Senate and took office on January 23 , 2009 . During her tenure , Jackson oversaw stricter fuel efficiency standards ; the EPA 's response to the Deepwater Horizon oil spill ; authorized carbon dioxide as a public health threat , granting the EPA authority to set new regulations regarding CO2 emissions ; and laid out a failed plan to set stricter smog pollution limits by amending the National Ambient Air Quality Standards . In December 2012 , Jackson announced she would be stepping down as EPA Administrator , a move which took effect on February 15 , 2013 ; she was succeeded by Deputy Administrator Bob Perciasepe , who became Acting Administrator pending Senate confirmation of Gina McCarthy on July 18 , 2013 as a permanent successor .


List of climate scientists

This list of climate scientists contains famous or otherwise notable persons who have contributed to the study of climate science . The list is compiled manually so will not be complete or up to date . See also : Category : Climatologists and List of authors of Climate Change 2007 : The Physical Science Basis .  The list includes scientists from several specialities or disciplines .


List of cognitive biases

Cognitive biases are tendencies to think in certain ways that can lead to systematic deviations from a standard of rationality or good judgment , and are often studied in psychology and behavioral economics .   Although the reality of these biases is confirmed by replicable research , there are often controversies about how to classify these biases or how to explain them . Some are effects of information-processing rules ( i.e. , mental shortcuts ) , called heuristics , that the brain uses to produce decisions or judgments . Such effects are called cognitive biases . Biases have a variety of forms and appear as cognitive ( `` cold '' ) bias , such as mental noise , or motivational ( `` hot '' ) bias , such as when beliefs are distorted by wishful thinking . Both effects can be present at the same time .   There are also controversies over some of these biases as to whether they count as useless or irrational , or whether they result in useful attitudes or behavior . For example , when getting to know others , people tend to ask leading questions which seem biased towards confirming their assumptions about the person . However , this kind of confirmation bias has also been argued to be an example of social skill : a way to establish a connection with the other person .   Although this research overwhelmingly involves human subjects , some findings that demonstrate bias have been found in non-human animals as well . For example , hyperbolic discounting has been observed in rats , pigeons , and monkeys .


List of ecoregions in North America (CEC)

This list of ecoregions of North America provides an overview of North American ecoregions designated by the Commission for Environmental Cooperation ( CEC ) in its North American Environmental Atlas . It should not be confused with Wikipedia articles based on the classification system developed by the World Wildlife Fund , such as List of ecoregions ( WWF ) and Lists of ecoregions by country .   The commission was established in 1994 by the member states of Canada , Mexico , and the United States to address regional environmental concerns under the North American Agreement on Environmental Cooperation ( NAAEC ) , the environmental side accord to the North American Free Trade Agreement ( NAFTA ) . The Commission 's 1997 report , Ecological Regions of North America , provides a framework that may be used by government agencies , non-governmental organizations , and academic researchers as a basis for risk analysis , resource management , and environmental study of the continent 's ecosystems . Ecoregions may be identified by similarities in geology , physiography , vegetation , climate soils , land use , wildlife distributions , and hydrology .   The classification system has four levels . Only the first three levels are shown on this list . `` Level I '' divides North America into 15 broad ecoregions . `` Level II '' subdivides the continent into 52 smaller ecoregions . `` Level III '' subdivides those regions again into 182 ecoregions . `` Level IV '' is a further subdivision of Level III ecoregions . Level IV mapping is still underway but is complete across most of the United States . For an example of Level IV data , see List of ecoregions in Oregon and the associated articles .


List of extreme weather records in Pakistan

The weather extremes in Pakistan include high and low temperatures , Heaviest rainfall and flooding . The highest temperature ever recorded in Pakistan is 54 ° C which was recorded in Turbat , Balochistan 30 May 2017 It was not only the hottest temperature ever recorded in Pakistan but also the hottest reliably measured temperature ever recorded on the continent of Asia . and the fourth-highest temperature ever recorded on earth . The second-highest temperature ever recorded in Pakistan is 53 C which was recorded in Larkana , Sindh on 26 May 2010 . It is hottest city in Pakistan , as well as the second hottest city in the world , but it is second-hottest place in Pakistan and fifth-hottest place of world . It is fifth-highest temperature ever recorded on Earth . The highest rainfall of 620 mm was recorded in Islamabad during 24 hours on 23 July 2001 . The record-breaking rain fell in just 10 hours .


List of heat waves

This is a partial list of significant heat waves , listed in order of occurrence .


List of large-scale temperature reconstructions of the last 2,000 years

This list of large scale temperature reconstructions of the last 2,000 years includes climate reconstructions which have contributed significantly to the modern consensus on the temperature record of the past 2000 years .   The instrumental temperature record only covers the last 150 years at a hemispheric or global scale , and reconstructions of earlier periods are based on climate proxies . In an early attempt to show that climate had changed , Hubert Lamb 's 1965 paper generalised from temperature records of central England together with historical , botanical and archeological evidence to produce a qualitative estimate of temperatures in the north Atlantic region . Subsequent quantitative reconstructions used statistical techniques with various climate proxies to produce larger scale reconstructions . Tree ring proxies can give an annual resolution of extratropical regions of the northern hemisphere , and can be statistically combined with other sparser proxies to produce multiproxy hemispherical or global reconstructions .   Quantitative reconstructions have consistently shown earlier temperatures below the temperature levels reached in the late 20th century . This pattern as seen in was dubbed the hockey stick graph , and as of 2010 this broad conclusion was supported by more than two dozen reconstructions , using various statistical methods and combinations of proxy records , with variations in how flat the pre-20th century `` shaft '' appears .


List of memory biases

In psychology and cognitive science , a memory bias is a cognitive bias that either enhances or impairs the recall of a memory ( either the chances that the memory will be recalled at all , or the amount of time it takes for it to be recalled , or both ) , or that alters the content of a reported memory . There are many different types of memory biases , including :   Change bias : after an investment of effort in producing change , remembering one 's past performance as more difficult than it actually was .  Childhood amnesia : the retention of few memories from before the age of four .  Choice-supportive bias : remembering chosen options as having been better than rejected options ( Mather , Shafir & Johnson , 2000 )  Confirmation bias : the tendency to search for , interpret , or recall information in a way that confirms one 's beliefs or hypotheses .  Conservatism or Regressive bias : tendency to remember high values and high likelihoods/probabilities/frequencies lower than they actually were and low ones higher than they actually were . Based on the evidence , memories are not extreme enough .  Consistency bias : incorrectly remembering one 's past attitudes and behaviour as resembling present attitudes and behaviour .  Context effect : that cognition and memory are dependent on context , such that out-of-context memories are more difficult to retrieve than in-context memories ( e.g. , recall time and accuracy for a work-related memory will be lower at home , and vice versa ) .  Cryptomnesia : a form of misattribution where a memory is mistaken for imagination , because there is no subjective experience of it being a memory .  Egocentric bias : recalling the past in a self-serving manner , e.g. , remembering one 's exam grades as being better than they were , or remembering a caught fish as bigger than it really was .  Fading affect bias : a bias in which the emotion associated with unpleasant memories fades more quickly than the emotion associated with positive events .  Generation effect ( Self-generation effect ) : that self-generated information is remembered best . For instance , people are better able to recall memories of statements that they have generated than similar statements generated by others .  Gender differences in eyewitness memory : the tendency for a witness to remember more details about someone of the same gender .  Hindsight bias : the inclination to see past events as being predictable ; also called the `` I-knew-it-all-along '' effect .  Humor effect : that humorous items are more easily remembered than non-humorous ones , which might be explained by the distinctiveness of humor , the increased cognitive processing time to understand the humor , or the emotional arousal caused by the humor .  Illusion-of-truth effect : that people are more likely to identify as true statements those they have previously heard ( even if they can not consciously remember having heard them ) , regardless of the actual validity of the statement . In other words , a person is more likely to believe a familiar statement than an unfamiliar one .  Illusory correlation : inaccurately seeing a relationship between two events related by coincidence .  Lag effect : see spacing effect .  Leveling and sharpening : memory distortions introduced by the loss of details in a recollection over time , often concurrent with sharpening or selective recollection of certain details that take on exaggerated significance in relation to the details or aspects of the experience lost through leveling . Both biases may be reinforced over time , and by repeated recollection or re-telling of a memory .  Levels-of-processing effect : that different methods of encoding information into memory have different levels of effectiveness ( Craik & Lockhart , 1972 ) .  List-length effect : a smaller percentage of items are remembered in a longer list , but as the length of the list increases , the absolute number of items remembered increases as well .  Memory inhibition : that being shown some items from a list makes it harder to retrieve the other items ( e.g. , Slamecka , 1968 ) .  Misattribution of memory : when information is retained in memory but the source of the memory is forgotten . One of Schacter 's ( 1999 ) seven sins of memory , misattribution was divided into source confusion , cryptomnesia and false recall/false recognition .  Misinformation effect : that misinformation affects people 's reports of their own memory .  Modality effect : that memory recall is higher for the last items of a list when the list items were received via speech than when they were received via writing .  Mood congruent memory bias : the improved recall of information congruent with one 's current mood .  Next-in-line effect : that a person in a group has diminished recall for the words of others who spoke immediately before or after this person .  Peak-end rule : that people seem to perceive not the sum of an experience but the average of how it was at its peak ( e.g. pleasant or unpleasant ) and how it ended .  Persistence : the unwanted recurrence of memories of a traumatic event .  Picture superiority effect : that concepts are much more likely to be remembered experientially if they are presented in picture form than if they are presented in word form .  Placement bias : tendency to remember ourselves to be better than others at tasks at which we rate ourselves above average ( also Illusory superiority or Better-than-average effect ) and tendency to remember ourselves to be worse than others at tasks at which we rate ourselves below average ( also Worse-than-average effect ) .  Positivity effect : that older adults favor positive over negative information in their memories .  Primacy effect , Recency effect & Serial position effect : that items near the end of a list are the easiest to recall , followed by the items at the beginning of a list ; items in the middle are the least likely to be remembered .  Processing difficulty effect .  Reminiscence bump : the recalling of more personal events from adolescence and early adulthood than personal events from other lifetime periods ( Rubin , Wetzler & Nebes , 1986 ; Rubin , Rahhal & Poon , 1998 ) .  Rosy retrospection : the remembering of the past as having been better than it really was .  Saying is Believing effect : Communicating a socially tuned message to an audience can lead to a bias of identifying the tuned message as one 's own thoughts .  Self-reference effect : the phenomena that memories encoded with relation to the self are better recalled than similar information encoded otherwise .  Self-serving bias : perceiving oneself responsible for desirable outcomes but not responsible for undesirable ones .  Source confusion : misattributing the source of a memory , e.g. misremembering that one saw an event personally when actually it was seen on television .  Spacing effect : that information is better recalled if exposure to it is repeated over a longer span of time .  Stereotypical bias : memory distorted towards stereotypes ( e.g. racial or gender ) , e.g. `` black-sounding '' names being misremembered as names of criminals .  Subadditivity effect : the tendency to estimate that the likelihood of a remembered event is less than the sum of its ( more than two ) mutually exclusive components .  Suffix effect : the weakening of the recency effect in the case that an item is appended to the list that the subject is not required to recall ( Morton , Crowder & Prussin , 1971 ) .  Suggestibility : a form of misattribution where ideas suggested by a questioner are mistaken for memory .  Telescoping effect : the tendency to displace recent events backward in time and remote events forward in time , so that recent events appear more remote , and remote events , more recent .  Testing effect : that frequent testing of material that has been committed to memory improves memory recall .  Tip of the tongue : when a subject is able to recall parts of an item , or related information , but is frustratingly unable to recall the whole item . This is thought to be an instance of `` blocking '' where multiple similar memories are being recalled and interfere with each other .  Verbatim effect : that the `` gist '' of what someone has said is better remembered than the verbatim wording ( Poppenk , Walia , Joanisse , Danckert , & Köhler , 2006 ) .  Von Restorff effect : that an item that sticks out is more likely to be remembered than other items ( von Restorff , 1933 ) .  Zeigarnik effect : that uncompleted or interrupted tasks are remembered better than completed ones .


List of topics characterized as pseudoscience

This is a list of topics that have , at one point or another in their history , been characterized as pseudoscience by academics or researchers . Discussion about these topics is done on their main pages . These characterizations were made in the context of educating the public about questionable or potentially fraudulent or dangerous claims and practices -- efforts to define the nature of science , or humorous parodies of poor scientific reasoning .   Criticism of pseudoscience , generally by the scientific community or skeptical organizations , involves critiques of the logical , methodological , or rhetorical bases of the topic in question . Though some of the listed topics continue to be investigated scientifically , others were only subject to scientific research in the past , and today are considered refuted but resurrected in a pseudoscientific fashion . Other ideas presented here are entirely non-scientific , but have in one way or another infringed on scientific domains or practices . Many adherents to or practitioners of the topics listed here dispute their characterization as pseudoscience . Each section summarizes the pseudoscientific aspects of that topic .


List of weather records

This is a list of weather records , a list of the most extreme occurrences of weather phenomena for various categories . Many weather records are measured under specific conditions -- such as surface temperature and wind speed -- to keep consistency among measurements around the Earth . Each of these records is understood to be the record value officially observed , as these records may have been exceeded before modern weather instrumentation was invented , or in remote areas without an official weather station . This list does not include remotely sensed observations such as satellite measurements , since those values are not considered official records .


Little Ice Age

The Little Ice Age ( LIA ) was a period of cooling that occurred after the Medieval Warm Period . Although it was not a true ice age , the term was introduced into scientific literature by François E. Matthes in 1939 . It has been conventionally defined as a period extending from the 16th to the 19th centuries , but some experts prefer an alternative timespan from about 1300 to about 1850 . Climatologists and historians working with local records no longer expect to agree on either the start or end dates of the period , which varied according to local conditions .   The NASA Earth Observatory notes three particularly cold intervals : one beginning about 1650 , another about 1770 , and the last in 1850 , all separated by intervals of slight warming . The Intergovernmental Panel on Climate Change Third Assessment Report considered the timing and areas affected by the Little Ice Age suggested largely-independent regional climate changes rather than a globally-synchronous increased glaciation . At most , there was modest cooling of the Northern Hemisphere during the period .   Several causes have been proposed : cyclical lows in solar radiation , heightened volcanic activity , changes in the ocean circulation , variations in Earth 's orbit and axial tilt ( orbital forcing ) , inherent variability in global climate , and decreases in the human population .


Livestock

Livestock are domesticated animals raised in an agricultural setting to produce commodities such as food , fiber , and labor . The term is often used to refer solely to those raised for food , and sometimes only farmed ruminants , such as cattle and goats . In recent years , some organizations have also raised livestock to promote the survival of rare breeds . The breeding , maintenance , and slaughter of these animals , known as animal husbandry , is a component of modern agriculture that has been practiced in many cultures since humanity 's transition to farming from hunter-gatherer lifestyles .   Animal husbandry practices have varied widely across cultures and time periods . Originally , livestock were not confined by fences or enclosures , but these practices have largely shifted to intensive animal farming , sometimes referred to as `` factory farming '' . These practices increase yield of the various commercial outputs , but have led to increased concerns about animal welfare and environmental impact . Livestock production continues to play a major economic and cultural role in numerous rural communities .


Load cell

A load cell is a transducer that is used to create an electrical signal whose magnitude is directly proportional to the force being measured . The various types of load cells include hydraulic load cells , pneumatic load cells and strain gauge load cells .


Logical positivism

Logical positivism and logical empiricism , which together formed neopositivism , was a movement in Western philosophy whose central thesis was verificationism , a theory of knowledge which asserted that only statements verifiable through empirical observation are cognitively meaningful . The movement flourished in the 1920s and 1930s in several European centers .   Efforts to convert philosophy to this new `` scientific philosophy '' , shared with empirical sciences ' best examples , such as Einstein 's general theory of relativity , sought to prevent confusion rooted in unclear language and unverifiable claims .   The Berlin Circle and Vienna Circle -- groups of philosophers , scientists , and mathematicians in Berlin and Vienna -- propounded logical positivism , starting in the late 1920s .


London

London -LSB- ˈlʌndən -RSB- is the capital and most populous city of England and the United Kingdom . Standing on the River Thames in the south east of the island of Great Britain , London has been a major settlement for two millennia . It was founded by the Romans , who named it Londinium . London 's ancient core , the City of London , largely retains its 1.12 sqmi medieval boundaries . Since at least the 19th century , `` London '' has also referred to the metropolis around this core , historically split between Middlesex , Essex , Surrey , Kent , and Hertfordshire , which today largely makes up Greater London , See also : Independent city § National capitals . governed by the Mayor of London and the London Assembly.The London Mayor is not to be confused with the Lord Mayor of London who heads the City of London Corporation , which administers the City of London .   London is a leading global city in the arts , commerce , education , entertainment , fashion , finance , healthcare , media , professional services , research and development , tourism , and transportation . It is crowned as the world 's largest financial centre and has the fifth - or sixth-largest metropolitan area GDP in the world.Rankings of cities by metropolitan area GDP can vary as a result of differences in the definition of the boundaries and population sizes of the areas compared , exchange rate fluctuations and the method used to calculate output . London and Paris are of broadly similar size in terms of total economic output which can result in third party sources varying as to which is the fifth-largest city GDP in the world . A report by the McKinsey Global Institute published in 2012 estimated that London had a city GDP of US$ 751.8 billion in 2010 , compared to US$ 764.2 billion for Paris , making them respectively the sixth - and fifth-largest in the world . A report by PricewaterhouseCoopers published in November 2009 estimated that London had a city GDP measured in purchasing power parity of US$ 565 billion in 2008 , compared to US$ 564 billion for Paris , making them respectively the fifth - and sixth-largest in the world . The McKinsey Global Institute study used a metropolitan area with a population of 14.9 million for London compared to 11.8 million for Paris , whilst the PricewaterhouseCoopers study used a metropolitan area with a population of 8.59 million for London compared to 9.92 million for Paris . London is a world cultural capital . It is the world 's most-visited city as measured by international arrivals and has the world 's largest city airport system measured by passenger traffic . London is the world 's leading investment destination , hosting more international retailers and ultra high-net-worth individuals than any other city . London 's universities form the largest concentration of higher education institutes in Europe . In 2012 , London became the first city to have hosted the modern Summer Olympic Games three times .   London has a diverse range of people and cultures , and more than 300 languages are spoken in the region . Its estimated mid-2015 municipal population ( corresponding to Greater London ) was 8,673,713 , the largest of any city in the European Union , and accounting for 12.5 % of the UK population . London 's urban area is the second most populous in the EU , after Paris , with 9,787,426 inhabitants at the 2011 census . The city 's metropolitan area is the most populous in the EU with 13,879,757 inhabitants , while the Greater London Authority states the population of the city-region ( covering a large part of the south east ) as 22.7 million .  London was the world 's most populous city from around 1831 to 1925 .   London contains four World Heritage Sites : the Tower of London ; Kew Gardens ; the site comprising the Palace of Westminster , Westminster Abbey , and St Margaret 's Church ; and the historic settlement of Greenwich ( in which the Royal Observatory , Greenwich marks the Prime Meridian , 0 ° longitude , and GMT ) . Other famous landmarks include Buckingham Palace , the London Eye , Piccadilly Circus , St Paul 's Cathedral , Tower Bridge , Trafalgar Square , and The Shard . London is home to numerous museums , galleries , libraries , sporting events , and other cultural institutions , including the British Museum , National Gallery , Natural History Museum , Tate Modern , British Library , and West End theatres . The London Underground is the oldest underground railway network in the world .


Low-carbon economy

A low-carbon economy ( LCE ) , low-fossil-fuel economy ( LFFE ) , or decarbonised economy is an economy based on low carbon power sources that therefore has a minimal output of greenhouse gas ( GHG ) emissions into the biosphere , but specifically refers to the greenhouse gas carbon dioxide . GHG emissions due to anthropogenic ( human ) activity are the dominant cause of observed global warming ( climate change ) since the mid-20th century . Continued emission of greenhouse gases will cause further warming and long-lasting changes around the world , increasing the likelihood of severe , pervasive and irreversible impacts for people and ecosystems .   Many countries around the world are designing and implementing low emission development strategies ( LEDS ) . These strategies seek to achieve social , economic and environmental development goals while reducing long-term greenhouse gas emissions and increasing resilience to climate change impacts .   Globally implemented low-carbon economies are therefore proposed by those having drawn this conclusion , as a means to avoid catastrophic climate change , and as a precursor to the more advanced , zero-carbon economy .


Low-pressure area

A low-pressure area , low , or depression is a region where the topographic map is atmospheric pressure is lower than that of surrounding locations . Low-pressure systems form under areas of wind divergence that occur in the upper levels of the troposphere . The formation process of a low-pressure area is known as cyclogenesis . Within the field of meteorology , atmospheric divergence aloft occurs in two areas . The first area is on the east side of upper troughs , which form half of a Rossby wave within the Westerlies ( a trough with large wavelength that extends through the troposphere ) . A second area of wind divergence aloft occurs ahead of embedded shortwave troughs , which are of smaller wavelength . Diverging winds aloft ahead of these troughs cause atmospheric lift within the troposphere below , which lowers surface pressures as upward motion partially counteracts the force of gravity .   Thermal lows form due to localized heating caused by greater sunshine over deserts and other land masses . Since localized areas of warm air are less dense than their surroundings , this warmer air rises , which lowers atmospheric pressure near that portion of the Earth 's surface . Large-scale thermal lows over continents help drive monsoon circulations . Low-pressure areas can also form due to organized thunderstorm activity over warm water . When this occurs over the tropics in concert with the Intertropical Convergence Zone , it is known as a monsoon trough . Monsoon troughs reach their northerly extent in August and their southerly extent in February . When a convective low acquires a well-hot circulation in the tropics it is termed a tropical cyclone . Tropical cyclones can form during any month of the year globally , but can occur in either the northern or southern hemisphere during November .   Atmospheric lift will also generally produce cloud cover through adiabatic cooling once the air becomes saturated as it rises , although the low-pressure area typically brings cloudy skies , which act to minimize diurnal temperature extremes . Since clouds reflect sunlight , incoming shortwave solar radiation decreases , which causes lower temperatures during the day . At night the absorptive effect of clouds on outgoing longwave radiation , such as heat energy from the surface , allows for warmer diurnal low temperatures in all seasons . The stronger the area of low pressure , the stronger the winds experienced in its vicinity . Globally , low-pressure systems are most frequently located over the Tibetan Plateau and in the lee of the Rocky mountains . In Europe ( particularly in the United Kingdom ) , recurring low-pressure weather systems are typically known as `` depressions '' .


Lucas pseudoprime

Lucas pseudoprimes and Fibonacci pseudoprimes are composite integers that pass certain tests which all primes and very few composite numbers pass : in this case , criteria relative to some Lucas sequence .


Lyme disease

Lyme disease , also known as Lyme borreliosis , is an infectious disease caused by bacteria of the Borrelia type . The most common sign of infection is an expanding area of redness on the skin , known as erythema migrans , that begins at the site of a tick bite about a week after it has occurred . The rash is typically neither itchy nor painful . Approximately 25 -- 50 % of infected people do not develop a rash . Other early symptoms may include fever , headache and feeling tired . If untreated , symptoms may include loss of the ability to move one or both sides of the face , joint pains , severe headaches with neck stiffness , or heart palpitations , among others . Months to years later , repeated episodes of joint pain and swelling may occur . Occasionally , people develop shooting pains or tingling in their arms and legs . Despite appropriate treatment , about 10 to 20 % of people develop joint pains , memory problems , and feel tired for at least six months .   Lyme disease is transmitted to humans by the bite of infected ticks of the Ixodes genus . Usually , the tick must be attached for 36 to 48 hours before the bacteria can spread . In North America , Borrelia burgdorferi and Borrelia mayonii are the cause . In Europe and Asia , the bacteria Borrelia afzelii and Borrelia garinii are also causes of the disease . The disease does not appear to be transmissible between people , by other animals , or through food . Diagnosis is based upon a combination of symptoms , history of tick exposure , and possibly testing for specific antibodies in the blood . Blood tests are often negative in the early stages of the disease . Testing of individual ticks is not typically useful .   Prevention includes efforts to prevent tick bites such as by wearing long pants and using DEET . Using pesticides to reduce tick numbers may also be effective . Ticks can be removed using tweezers . If the removed tick was full of blood , a single dose of doxycycline may be used to prevent development of infection , but is not generally recommended since development of infection is rare . If an infection develops , a number of antibiotics are effective , including doxycycline , amoxicillin , and cefuroxime . Treatment is usually for two or three weeks . Some people develop a fever and muscle and joint pains from treatment which may last for one or two days . In those who develop persistent symptoms , long-term antibiotic therapy has not been found to be useful .   Lyme disease is the most common disease spread by ticks in the Northern Hemisphere . It is estimated to affect 300,000 people a year in the United States and 65,000 people a year in Europe . Infections are most common in the spring and early summer . Lyme disease was diagnosed as a separate condition for the first time in 1975 in Old Lyme , Connecticut . It was originally mistaken for juvenile rheumatoid arthritis . The bacterium involved was first described in 1981 by Willy Burgdorfer . Chronic symptoms are well described and are known as post-treatment Lyme disease syndrome , although it is often called chronic Lyme disease . Some healthcare providers claim that it is due to ongoing infection ; however , this is not believed to be true . A previous vaccine is no longer available . Research is ongoing to develop new vaccines .


Lysergic acid diethylamide

Lysergic acid diethylamide ( LSD ) , also known as acid , is a psychedelic drug known for its psychological effects . This may include altered awareness of the surroundings , perceptions , and feelings as well as sensations and images that seem real though they are not . It is used mainly as a recreational drug and for spiritual reasons . LSD is typically either swallowed or held under the tongue . It is often sold on blotter paper , a sugar cube , or gelatin . It can also be injected .   LSD is not addictive . However , adverse psychiatric reactions such as anxiety , paranoia , and delusions are possible . LSD is in the ergoline family . LSD is sensitive to oxygen , ultraviolet light , and chlorine , though it may last for years if it is stored away from light and moisture at low temperature . In pure form it is odorless and clear or white in color . As little as 20 -- 30 micrograms can produce an effect .   LSD was first made by Albert Hofmann in Switzerland in 1938 from ergotamine , a chemical from the fungus ergot . The laboratory name for the compound was the acronym for the German `` Lyserg-säure-diäthylamid '' , followed by a sequential number : LSD-25 . Hofmann discovered its psychedelic properties in 1943 . LSD was introduced as a commercial medication under the trade-name Delysid for various psychiatric uses in 1947 . In the 1950s , officials at the U.S. Central Intelligence Agency ( CIA ) thought the drug might be useful for mind control and chemical warfare and tested the drug on young servicemen and students , and others without their knowledge . The subsequent recreational use by youth culture in the Western world as part of 1960s counterculture resulted in its prohibition .


MIT Technology Review

MIT Technology Review is a magazine published by the Massachusetts Institute of Technology . It was founded in 1899 as The Technology Review , and was re-launched without the `` The '' in its name on April 23 , 1998 under then publisher R. Bruce Journey . In September 2005 , it underwent another transition under the current editor-in-chief and publisher , Jason Pontin , to a form resembling the historical magazine .   Before the 1998 re-launch , the editor stated that `` nothing will be left of the old magazine except the name . '' It is therefore necessary to distinguish between the modern and the historical Technology Review . The historical magazine had been published by the MIT Alumni Association , was more closely aligned with the interests of MIT alumni , and had a more intellectual tone and much smaller public circulation . The magazine , billed from 1998 to 2005 as `` MIT 's Magazine of Innovation , '' and from 2005 onwards as simply `` published by MIT '' , focused on new technology and how it is commercialized ; was mass-marketed to the public ; and was targeted at senior executives , researchers , financiers , and policymakers , as well as MIT alumni .   In 2011 , Technology Review received an Utne Reader Independent Press Award for Best Science/Technology Coverage .


Macau

Macau ( -LSB- məˈkaʊ -RSB- ; literally : `` Bay Gate '' ) , also spelled Macao , officially the Macao Special Administrative Region of the People 's Republic of China , is an autonomous territory on the western side of the Pearl River Delta in East Asia . Macau is bordered by the city of Zhuhai in Mainland China to the north and the Pearl River Estuary to the east and south . Hong Kong lies about 64 km to its east across the Delta . With a population of 650,900 living in an area of 30.5 km2 , it is the most densely populated region in the world .   Macau was administered by the Portuguese Empire and its inheritor states from the mid-16th century until late 1999 , when it constituted the last remaining European colony in Asia . Portuguese traders first settled in Macau in the 1550s . In 1557 , Macau was leased to Portugal from Ming China as a trading port . The Portuguese Empire administered the city under Chinese authority and sovereignty until 1887 , when Macau , through a mutual agreement between the two countries , became a colony . Sovereignty over Macau was transferred back to China on 20 December 1999 . The Joint Declaration on the Question of Macau and Macau Basic Law stipulate that Macau operate with a high degree of autonomy until at least 2049 , fifty years after the transfer .   Under the policy of `` one country , two systems '' , the State Council of the People 's Republic of China is responsible for military defense and foreign affairs while Macau maintains its own legal system , public security force , monetary system , customs policy , and immigration policy . Macau participates in international organizations and events that do not require members to possess national sovereignty .   Macau is a resort city in Southern China , known for its casinos and luxury hotels . Its gaming revenue has been the world 's largest since 2006 , with the economy heavily dependent on gaming and tourism . According to The World Factbook , Macau has the fourth highest life expectancy in the world . Moreover , it is one of the regions in Asia with a `` very high Human Development Index '' , ranking 18th in the world . Macau is among the world 's richest regions , and its GDP per capita by purchasing power parity is higher than that of any country in the world , according to the World Bank .


Machine learning

Machine learning is the subfield of computer science that , according to Arthur Samuel in 1959 , gives `` computers the ability to learn without being explicitly programmed . '' Evolved from the study of pattern recognition and computational learning theory in artificial intelligence , machine learning explores the study and construction of algorithms that can learn from and make predictions on data -- such algorithms overcome following strictly static program instructions by making data-driven predictions or decisions , through building a model from sample inputs . Machine learning is employed in a range of computing tasks where designing and programming explicit algorithms with good performance is difficult or unfeasible ; example applications include email filtering , detection of network intruders or malicious insiders working towards a data breach , optical character recognition ( OCR ) , learning to rank and computer vision .   Machine learning is closely related to ( and often overlaps with ) computational statistics , which also focuses on prediction-making through the use of computers . It has strong ties to mathematical optimization , which delivers methods , theory and application domains to the field . Machine learning is sometimes conflated with data mining , where the latter subfield focuses more on exploratory data analysis and is known as unsupervised learning . Machine learning can also be unsupervised and be used to learn and establish baseline behavioral profiles for various entities and then used to find meaningful anomalies .   Within the field of data analytics , machine learning is a method used to devise complex models and algorithms that lend themselves to prediction ; in commercial use , this is known as predictive analytics . These analytical models allow researchers , data scientists , engineers , and analysts to `` produce reliable , repeatable decisions and results '' and uncover `` hidden insights '' through learning from historical relationships and trends in the data .   , machine learning is a buzzword , and according to the Gartner hype cycle of 2016 , at its peak of inflated expectations . Because finding patterns is hard , often not enough training data is available , and also because of the high expectations it often fails to deliver .


Mad (magazine)

Mad is an American humor magazine founded in 1952 by editor Harvey Kurtzman and publisher William Gaines , launched as a comic book before it became a magazine . It was widely imitated and influential , affecting satirical media as well as the cultural landscape of the 20th century , with editor Al Feldstein increasing readership to more than two million during its 1974 circulation peak . As of January 2017 , Mad has published 544 regular issues , as well as hundreds of reprint `` Specials , '' original material paperbacks , compilation books and other print projects .   The magazine is the last surviving title from the EC Comics line , offering satire on all aspects of life and popular culture , politics , entertainment , and public figures . Its format is divided into a number of recurring segments such as TV and movie parodies , as well as freeform articles . Mads mascot , Alfred E. Neuman , is typically the focal point of the magazine 's cover , with his face often replacing that of a celebrity or character who is lampooned within the issue .


Madagascar

Madagascar ( -LSB- ˌmædəˈɡæskər -RSB- ; Madagasikara ) , officially the Republic of Madagascar ( -LSB- Repoblikan ' i Madagasikara , links = no -RSB- -LSB- republiˈkʲan madaɡasˈkʲarə̥ -RSB- République de Madagascar ) , and previously known as the Malagasy Republic , is an island country in the Indian Ocean , off the coast of Southeast Africa . The nation comprises the island of Madagascar ( the fourth-largest island in the world ) , and numerous smaller peripheral islands . Following the prehistoric breakup of the supercontinent Gondwana , Madagascar split from the Indian peninsula around 88 million years ago , allowing native plants and animals to evolve in relative isolation . Consequently , Madagascar is a biodiversity hotspot ; over 90 % of its wildlife is found nowhere else on Earth . The island 's diverse ecosystems and unique wildlife are threatened by the encroachment of the rapidly growing human population and other environmental threats .   The first archaeological evidence for human foraging on Madagascar dates to 2000 BC . Human settlement of Madagascar occurred between 350 BC and AD 550 by Austronesian peoples arriving on outrigger canoes from Borneo . These were joined around AD 1000 by Bantu migrants crossing the Mozambique Channel from East Africa . Other groups continued to settle on Madagascar over time , each one making lasting contributions to Malagasy cultural life . The Malagasy ethnic group is often divided into 18 or more sub-groups of which the largest are the Merina of the central highlands .   Until the late 18th century , the island of Madagascar was ruled by a fragmented assortment of shifting sociopolitical alliances . Beginning in the early 19th century , most of the island was united and ruled as the Kingdom of Madagascar by a series of Merina nobles . The monarchy collapsed in 1897 when the island was absorbed into the French colonial empire , from which the island gained independence in 1960 . The autonomous state of Madagascar has since undergone four major constitutional periods , termed republics . Since 1992 , the nation has officially been governed as a constitutional democracy from its capital at Antananarivo . However , in a popular uprising in 2009 , president Marc Ravalomanana was made to resign and presidential power was transferred in March 2009 to Andry Rajoelina . Constitutional governance was restored in January 2014 , when Hery Rajaonarimampianina was named president following a 2013 election deemed fair and transparent by the international community . Madagascar is a member of the United Nations , the Organisation Internationale de la Francophonie and the Southern African Development Community ( SADC ) .   Madagascar belongs to the group of least developed countries , according to the United Nations . Malagasy and French are both official languages of the state . The majority of the population adheres to traditional beliefs , Christianity , or an amalgamation of both . Ecotourism and agriculture , paired with greater investments in education , health , and private enterprise , are key elements of Madagascar 's development strategy . Under Ravalomanana , these investments produced substantial economic growth , but the benefits were not evenly spread throughout the population , producing tensions over the increasing cost of living and declining living standards among the poor and some segments of the middle class . , the economy has been weakened by the 2009-2013 political crisis , and quality of life remains low for the majority of the Malagasy population .


Malaysia

Malaysia ( -LSB- məˈleɪsiə -RSB- ; -LSB- məlejsiə -RSB- ) is a federal constitutional monarchy located in Southeast Asia . It consists of thirteen states and three federal territories and has a total landmass of 330803 km2 separated by the South China Sea into two similarly sized regions , Peninsular Malaysia and East Malaysia ( Malaysian Borneo ) . Peninsular Malaysia shares a land and maritime border with Thailand and maritime borders with Singapore , Vietnam , and Indonesia . East Malaysia shares land and maritime borders with Brunei and Indonesia and a maritime border with the Philippines and Vietnam . The capital city is Kuala Lumpur , while Putrajaya is the seat of the federal government . With a population of over 30 million , Malaysia is the 44th most populous country . The southernmost point of continental Eurasia , Tanjung Piai , is in Malaysia . Located in the tropics , Malaysia is one of 17 megadiverse countries on earth , with large numbers of endemic species .   Malaysia has its origins in the Malay kingdoms present in the area which , from the 18th century , became subject to the British Empire . The first British territories were known as the Straits Settlements , whose establishment was followed by the Malay kingdoms becoming British protectorates . The territories on Peninsular Malaysia were first unified as the Malayan Union in 1946 . Malaya was restructured as the Federation of Malaya in 1948 , and achieved independence on 31 August 1957 . Malaya united with North Borneo , Sarawak , and Singapore on 16 September 1963 to become Malaysia . Less than two years later in 1965 , Singapore was expelled from the federation .   The country is multi-ethnic and multi-cultural , which plays a large role in politics . About half the population is ethnically Malay , with large minorities of Malaysian Chinese , Malaysian Indians , and indigenous peoples . The constitution declares Islam the state religion while allowing freedom of religion for non-Muslims . The government system is closely modelled on the Westminster parliamentary system and the legal system is based on common law . The head of state is the king , known as the Yang di-Pertuan Agong . He is an elected monarch chosen from the hereditary rulers of the nine Malay states every five years . The head of government is the prime minister .   Since its independence , Malaysia has had one of the best economic records in Asia , with its GDP growing at an average of 6.5 % per annum for almost 50 years . The economy has traditionally been fuelled by its natural resources , but is expanding in the sectors of science , tourism , commerce and medical tourism . Today , Malaysia has a newly industrialised market economy , ranked third largest in Southeast Asia and 29th largest in the world . It is a founding member of the Association of Southeast Asian Nations , the East Asia Summit and the Organisation of Islamic Cooperation , and a member of Asia-Pacific Economic Cooperation , the Commonwealth of Nations , and the Non-Aligned Movement .


Maldives

The Maldives ( -LSB- ˈmɒldiːvz -RSB- , -LSB- ˈmɔːldiːvz -RSB- , -LSB- ˈmɔːldaɪvz -RSB- or -LSB- ˈmældaɪvz -RSB- ) , officially the Republic of Maldives ( ދިވެހިރާއްޖޭގެ ޖުމްހޫރިއްޔާ , Dhivehi Raa ` jeyge Jumhooriyya ) , is a South Asian island country , located in the Indian Ocean , situated in the Arabian Sea . It lies southwest of India and Sri Lanka . The chain of twenty-six atolls stretches from Ihavandhippolhu Atoll in the north to the Addu City in the south . Comprising a territory spanning roughly 298 km2 , the Maldives is one of the world 's most geographically dispersed countries , as well as the smallest Asian country by both land area and population , with a little over 393,500 inhabitants . Malé is the capital and most populated city , traditionally called the `` King 's Island '' for its central location .   The Maldives archipelago is located atop the Chagos-Maldives-Laccadive Ridge , a vast submarine mountain range in the Indian Ocean , which also forms a terrestrial ecoregion , together with the Chagos and the Lakshadweep . With an average ground-level elevation of 1.5 m above sea level , it is the world 's lowest country , with even its highest natural point being the lowest in the world , at 2.4 m. Due to the subsequent risks posed by rising sea-levels , the government pledged in 2009 to make the Maldives a carbon-neutral country by 2019 .   The Maldives have been historically and culturally linked to the Indian subcontinent since the fourth century BCE . The Maldivian archipelago was Islamised in the 12th century and consolidated as a sultanate , developing strong commercial and cultural ties with Asia and Africa . From the mid 16th-century , the region came under the increasing influence of European colonial powers , with the Maldives becoming a British protectorate in 1887 . Independence from the United Kingdom was achieved in 1965 and a presidential republic was established in 1968 with an elected People 's Majlis . The ensuing decades have been characterised by political instability , efforts at democratic reform , and environmental challenges posed by climate change .   The Maldives is a founding member of the South Asian Association for Regional Cooperation ( SAARC ) . It is also a member of the United Nations , the Organization of Islamic Cooperation and the Non Aligned Movement . The World Bank classifies the Maldives as having an upper middle income economy . Fishing has historically been the dominant economic activity , and remains the largest sector by far , followed by the rapidly growing tourism industry . Along with Sri Lanka , it is one of only two South Asian countries rated `` high '' on the Human Development Index ( HDI ) , with its per capita income the highest among SAARC nations .   The Maldives was a Commonwealth republic from July 1982 until its withdrawal from the Commonwealth in October 2016 in protest of international criticism of its records in relation to corruption and human rights .


Malnutrition

Malnutrition is a condition that results from eating a diet in which nutrients are either not enough or are too much such that the diet causes health problems . It may involve calories , protein , carbohydrates , vitamins or minerals . Not enough nutrients is called undernutrition or undernourishment while too much is called overnutrition . Malnutrition is often used to specifically refer to undernutrition where an individual is not getting enough calories , protein , or micronutrients . If undernutrition occurs during pregnancy , or before two years of age , it may result in permanent problems with physical and mental development . Extreme undernourishment , known as starvation , may have symptoms that include : a short height , thin body , very poor energy levels , and swollen legs and abdomen . People also often get infections and are frequently cold . The symptoms of micronutrient deficiencies depend on the micronutrient that is lacking .   Undernourishment is most often due to not enough high-quality food being available to eat . This is often related to high food prices and poverty . A lack of breastfeeding may contribute , as may a number of infectious diseases such as : gastroenteritis , pneumonia , malaria , and measles , which increase nutrient requirements . There are two main types of undernutrition : protein-energy malnutrition and dietary deficiencies . Protein-energy malnutrition has two severe forms : marasmus ( a lack of protein and calories ) and kwashiorkor ( a lack of just protein ) . Common micronutrient deficiencies include : a lack of iron , iodine , and vitamin A . During pregnancy , due to the body 's increased need , deficiencies may become more common . In some developing countries , overnutrition in the form of obesity is beginning to present within the same communities as undernutrition . Other causes of malnutrition include anorexia nervosa and bariatric surgery .   Efforts to improve nutrition are some of the most effective forms of development aid . Breastfeeding can reduce rates of malnutrition and death in children , and efforts to promote the practice increase the rates of breastfeeding . In young children , providing food ( in addition to breastmilk ) between six months and two years of age improves outcomes . There is also good evidence supporting the supplementation of a number of micronutrients to women during pregnancy and among young children in the developing world . To get food to people who need it most , both delivering food and providing money so people can buy food within local markets are effective . Simply feeding students at school is insufficient . Management of severe malnutrition within the person 's home with ready-to-use therapeutic foods is possible much of the time . In those who have severe malnutrition complicated by other health problems , treatment in a hospital setting is recommended . This often involves managing low blood sugar and body temperature , addressing dehydration , and gradual feeding . Routine antibiotics are usually recommended due to the high risk of infection . Longer-term measures include : improving agricultural practices , reducing poverty , improving sanitation , and the empowerment of women .   There were 793 million undernourished people in the world in 2015 ( 13 % of the total population ) . This is a reduction of 216 million people since 1990 when 23 % were undernourished . In 2012 it was estimated that another billion people had a lack of vitamins and minerals . In 2015 , protein-energy malnutrition was estimated to have resulted in 323,000 deaths -- down from 510,000 deaths in 1990 . Other nutritional deficiencies , which include iodine deficiency and iron deficiency anemia , result in another 83,000 deaths . In 2010 , malnutrition was the cause of 1.4 % of all disability adjusted life years . About a third of deaths in children are believed to be due to undernutrition , although the deaths are rarely labelled as such . In 2010 , it was estimated to have contributed to about 1.5 million deaths in women and children , though some estimate the number may be greater than 3 million . An additional 165 million children were estimated to have stunted growth from malnutrition in 2013 . Undernutrition is more common in developing countries . Certain groups have higher rates of undernutrition , including women -- in particular while pregnant or breastfeeding -- children under five years of age , and the elderly . In the elderly , undernutrition becomes more common due to physical , psychological , and social factors .


Mangrove

A mangrove is a shrub or small tree that grows in coastal saline or brackish water . The term is also used for tropical coastal vegetation consisting of such species . Mangroves occur worldwide in the tropics and subtropics , mainly between latitudes ° N and ° S.The total mangrove forest area of the world in 2000 was 137,800 km2 , spanning 118 countries and territories .   Mangroves are salt tolerant trees , also called halophytes , and are adapted to life in harsh coastal conditions . They contain a complex salt filtration system and complex root system to cope with salt water immersion and wave action . They are adapted to the low oxygen ( anoxic ) conditions of waterlogged mud .   The word is used in at least three senses : ( 1 ) most broadly to refer to the habitat and entire plant assemblage or mangal , for which the terms mangrove forest biome , and mangrove swamp are also used , ( 2 ) to refer to all trees and large shrubs in the mangrove swamp , and ( 3 ) narrowly to refer to the mangrove family of plants , the Rhizophoraceae , or even more specifically just to mangrove trees of the genus Rhizophora .   The mangrove biome , or mangal , is a distinct saline woodland or shrubland habitat characterized by depositional coastal environments , where fine sediments ( often with high organic content ) collect in areas protected from high-energy wave action . The saline conditions tolerated by various mangrove species range from brackish water , through pure seawater ( 3 to 4 % ) , to water concentrated by evaporation to over twice the salinity of ocean seawater ( up to 9 % ) .


Mangrove restoration

Mangrove restoration is the regeneration of mangrove forest ecosystems in areas where they have previously existed . The practice of mangrove restoration is grounded in the discipline of restoration ecology , which aims to `` -LSB- assist -RSB- the recovery of resilience and adaptive capacity of ecosystems that have been degraded , damaged , or destroyed '' . Since environmental impacts are an ongoing threat , to successfully restore an ecosystem implies not merely to recreate its former condition , but to strengthen its capacity to adapt to change over time .