text:
Return on assets
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The return on assets (ROA) shows the percentage of how profitable a company's assets are in generating revenue.
ROA can be computed as:
R O A = Net Income Average Total Assets {\displaystyle \mathrm {ROA} ={\frac {\mbox{Net Income}}{\mbox{Average Total Assets}}}} [1]
This number tells you what the company can do with what it has, i.e. how many dollars of earnings they derive from each dollar of assets they control. It's a useful number for comparing competing companies in the same industry. The number will vary widely across different industries. Return on assets gives an indication of the capital intensity of the company, which will depend on the industry; companies that require large initial investments will generally have lower return on assets. ROAs over 5% are generally considered good.
Contents
[hide]
1 Usage
2 See also
3 References
4 External links
Usage[edit]
Return on assets is one of the elements used in financial analysis using the Du Pont Identity.
See also[edit]
Rate of return on a portfolio
Return on capital
Weighted average return on assets (WARA)
List of business and finance abbreviations
Return on investment (ROI)
References[edit]
Jump up ^ Susan V. Crosson; Belverd E., Jr Needles; Needles, Belverd E.; Powers, Marian (2008). Principles of accounting. Boston: Houghton Mifflin. p. 209. ISBN 0-618-73661-1.
External links[edit]
Return On Assets - ROA
[hide]
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t
e
Financial ratios
Cyclically adjusted price-to-earnings (CAPE)
Capitalization rate (Cap Rate)
Cash return on cash invested (CROCI)
Debt-to-equity (D/E)
Dividend cover
Dividend payout
Enterprise value/EBITDA (EV/EBITDA)
Enterprise value/gross cash invested (EV/GCI)
Enterprise value/sales (EV/Sales)
Loan-to-value (LTV)
Omega
Operating margin
Price-to-book (P/B)
Price/cash flow (P/CF)
Price-earnings (P/E)
Price-earnings to growth (PEG)
Price-sales (P/S)
Profit margin
Return on assets (ROA)
Return on net assets (RONA)
Return on capital (ROC)
Return on capital employed (ROCE)
Return on equity (ROE)
Return on tangible equity (ROTE)
Risk-adjusted return on capital (RAROC)
Risk return (RRR)
Sharpe
Short interest (SIR)
Sortino
Sustainable growth (SGR)
Treynor
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Bull
From Wikipedia, the free encyclopedia
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For other uses, see Bull (disambiguation).
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2017) (Learn how and when to remove this template message)
A Charolais bull.
A bull is an intact (i.e., not castrated) adult male of the species Bos taurus (cattle). More muscular and aggressive than the female of the species, the cow, the bull has long been an important symbol in many cultures, and plays a significant role in both beef ranching and dairy farming, and in a variety of other cultural activities.
Contents
[hide]
1 Nomenclature
2 Characteristics
2.1 Reproductive anatomy
2.2 Behavior
3 Management
3.1 Beef production
3.2 Temperament and handling
3.3 Handling
3.4 Artificial insemination
4 Relationship with humans
5 Significance in human culture
6 See also
7 References
8 External links
Nomenclature[edit]
See also: List of animal names
The female counterpart to a bull is a cow, while a male of the species who has been castrated is a steer, ox[1] or bullock, although in North America this last term refers to a young bull, and in Australia to a draught animal. Usage of these terms varies considerably with area and dialect. Colloquially, people unfamiliar with cattle may refer to both castrated and intact animals as "bulls".
A wild, young, unmarked bull is known as a micky in Australia.[2] Improper or late castration on a bull results in it becoming a coarse steer, also known as a stag in Australia, Canada and New Zealand.[3] In some countries an incompletely castrated male is known also as a rig or ridgling.
The word "bull" also denotes the males of other bovines, including bison and water buffalo as well as many other species of large animals including elephants, camels, elk, moose, and whales.
Characteristics[edit]
A Scottish Highland bull
Bulls are much more muscular than cows, with thicker bones, larger feet, a very muscular neck, and a large, bony head with protective ridges over the eyes. These features assist bulls in fighting for domination over a herd, giving the winner superior access to cows for reproduction.[4] The hair is generally shorter on the body, but on the neck and head there is often a "mane" of curlier, wooly hair. Bulls are usually about the same height as cows or a little taller, but because of the additional muscle and bone mass they often weigh far more. Most of the time, a bull has a hump on its shoulders.[5] When a bull is full-grown, it can weigh as much as 2,000 pounds.[5]
In horned cattle the horns of bulls tend to be thicker and somewhat shorter than those of cows,[6] and in many breeds they curve outwards in a flat arc rather than upwards in a lyre shape. It is not true, as is commonly believed, that bulls have horns and cows do not: the presence of horns depends on the breed, or in horned breeds on whether the horns have been disbudded (conversely, in many breeds of sheep indeed only the males have horns). Cattle that naturally do not have horns are referred to as polled, or muleys.[7]
Castrated male cattle are physically similar to females in build and horn shape, although if allowed to reach maturity they may be considerably taller than either bulls or cows, with heavily muscled shoulders (but not necks).[8]
Reproductive anatomy[edit]
See also: Cattle § Anatomy
The reproductive system of a bull
Bulls become fertile at about seven months of age. Their fertility is closely related to the size of their testicles, and one simple test of fertility is to measure the circumference of the scrotum: a young bull is likely to be fertile once this reaches 28 centimetres (11 in); that of a fully adult bull may be over 40 centimetres (16 in).[9][10]
Bulls have a fibro-elastic penis. Given the small amount of erectile tissue, there is little enlargement after erection. The penis is quite rigid when non-erect, and becomes even more rigid during erection. Protrusion is not affected much by erection, but more by relaxation of the retractor penis muscle and straightening of the sigmoid flexure.[11][12][13] Bulls are occasionally affected by a condition known as "corkscrew penis".[14][15] The penis of a mature bull is about 3–4 cm in diameter,[16][17][18][19] and 80–100 cm in length.[20] The bull's glans penis has a rounded and elongated shape.[20]
Behavior[edit]
A common misconception widely repeated in depictions of bull behavior is that the color red angers bulls, inciting them to charge. In fact, like most mammals, cattle are red-green color blind.[21] In bullfighting, it is the movement of the matador's cape, and not the color, which provokes a reaction in the bull.
Management[edit]
Beef production[edit]
Other than the few bulls needed for breeding, the vast majority of male cattle are slaughtered for meat before the age of three years, except where they are needed (castrated) as work oxen for haulage. Most of these beef animals are castrated as calves to reduce aggressive behavior and prevent unwanted mating,[22] although some are reared as uncastrated bull beef. A bull is typically ready for slaughter one or two months sooner than a castrated male or a female, and produces proportionately more, leaner muscle.[22]
Frame score is a useful way of describing the skeletal size of bulls and other cattle. Frame scores can be used as an aid to predict mature cattle sizes and aid in the selection of beef bulls. Frame scores are calculated from hip height and age. In sales catalogues, this measurement is frequently reported in addition to weight and other performance data such as estimated breed value (EBV).[23]
Temperament and handling[edit]
A bull paws up dust in a threat display
A warning sign for a bull-occupied field
Adult bulls may weigh between 500 and 1,000 kilograms (1,100 and 2,200 lb). Most are capable of aggressive behavior and require careful handling to ensure safety of humans and other animals. Those of dairy breeds may be more prone to aggression, while beef breeds are somewhat less aggressive, though beef breeds such as the Spanish Fighting Bull and related animals are also noted for aggressive tendencies, which are further encouraged by selective breeding.
It is estimated that 42% of all livestock-related fatalities in Canada are a result of bull attacks, and fewer than one in twenty victims of a bull attack survives.[24] Dairy breed bulls are particularly dangerous and unpredictable; the hazards of bull handling are a significant cause of injury and death for dairy farmers in some parts of the United States[25][26][27] The need to move a bull in and out of its pen to cover cows exposes the handler to serious jeopardy of life and limb.[28] Being trampled, jammed against a wall or gored by a bull was one of the most frequent causes of death in the dairy industry before 1940.[29] With regard to such risks, one popular farming magazine has suggested, "Handle [the bull] with a staff and take no chances. The gentle bull, not the vicious one, most often kills or maims his keeper".[30]
On the other hand, and like other domestic animals, some bulls have saved human lives. For instance, when the Beast of Gevaudan terrorized people in France in the 18th century, some people were saved by their bulls.[31]
Handling[edit]
A bull with a nose ring, tethered to a picket
It is traditional in many areas to place rings in bulls' noses to help control them. The ring is usually made of copper, and is inserted through a small hole cut in the septum of the nose. It is used by attaching a lead rope either directly to it or running through it from a head collar, or for more difficult bulls, a bull pole (or bull staff) may be used. This is a rigid pole about 1 metre (3 ft) long with a clip at one end; this attaches to the ring and allows the bull both to be led and to be held away from his handler.
An aggressive bull may be kept confined in a bull pen: a robustly-constructed shelter and pen, often with an arrangement to allow the bull to be fed without entering the pen. If an aggressive bull is allowed to graze outside, additional precautions may be needed to help avoid his harming people. One method is a bull mask, which either covers the bull's eyes completely, or restricts his vision to the ground immediately in front of him, so he cannot see his potential victim. Another method is to attach a length of chain to the bull's nose-ring, so that if he ducks his head to charge, he steps on the chain and is brought up short. Alternatively, the bull may be hobbled, or chained by his ring or by a collar to a solid object such as a ring concreted into the ground.
In larger pastures, particularly where a bull is kept with other cattle, the animals may simply be fed from a pickup truck or tractor, the vehicle itself providing some protection for the humans involved. Generally, bulls kept with cows tend to be less aggressive than those kept alone. In herd situations, cows with young calves are often more dangerous to humans. In the off season, multiple bulls may be kept together in a "bachelor herd".
Artificial insemination[edit]
Bullfighting
See also: Frozen bovine semen
Many cattle ranches and stations run bulls with cows, and most dairy or beef farms traditionally had at least one, if not several, bulls for purposes of herd maintenance.[32][33] However, the problems associated with handling a bull (particularly where cows must be removed from its presence to be worked) has prompted many dairy farmers to restrict themselves to artificial insemination (AI) of the cows.[34] Semen is removed from the bulls and stored in canisters of liquid nitrogen, where it is kept until it can be sold, at which time it can be very profitable, in fact, many ranchers keep bulls specifically for this purpose. AI is also used to increase the quality of a herd, or to introduce an outcross of bloodlines. Some ranchers prefer to use AI to allow them to breed to several different bulls in a season or to breed their best stock to a higher quality bull than they could afford to purchase outright. AI may also be used in conjunction with embryo transfer to allow cattle producers to add new breeding to their herds.
Relationship with humans[edit]
A bull used in heraldry: Coat of arms of Mecklenburg region, Germany
An aurochs bull in a cave painting in Lascaux, France.
Aside from their reproductive duties, bulls are also used in certain sports, including bullfighting and bull riding. They are also incorporated into festivals and folk events such as the Running of the Bulls and were seen in ancient sports such as bull-leaping. Though less common than castrated males, bulls are used as draught oxen in some areas.[35][36] The once-popular sport of bull-baiting, in which a bull is attacked by specially bred and trained dogs (which came to be known as bulldogs), was banned in England by the Cruelty to Animals Act 1835.
As with other animals, some bulls have been regarded as pets. The singer Charo, for instance, has owned a pet bull named Manolo.[37]
Significance in human culture[edit]
Bulls have held a place of significance in human culture since before the beginning of recorded history. They appear in cave paintings estimated to be up to 17,000 years old. The mythic Bull of the Heavens plays a role in the ancient Sumerian Epic of Gilgamesh, dating as far back as 2150 BC. The importance of the bull is reflected in its appearance in the zodiac as Taurus, and its numerous appearances in mythology, where it is often associated with fertility. See also Korban. In Hinduism, a bull named Nandi, usually depicted seated, is worshipped as the vehicle of the god Shiva and depicted on many of the images of that God. Symbolically, the bull appears commonly in heraldry, and, in modern times, as a mascot for both amateur and professional sports teams.
See also[edit]
Cow-calf operation
References[edit]
Jump up ^ Delbridge, A, et al., Macquarie Dictionary, The Book Printer, Australia, 1991
Jump up ^ Sheena Coupe (ed.), Frontier Country, Vol. 1 (Weldon Russell Publishing, Willoughby, 1989), ISBN 1-875202-01-3
Jump up ^ "Sure Ways to Lose Money on Your Cattle". Spiritwoodstockyards.ca. Retrieved 2012-08-06.
Jump up ^ C. J. C. Phillips, Principles of Cattle Production (2010), p. 50.
^ Jump up to: a b Woods, Katie (30 July 2015). "How to determine if cattle are bulls, steers, cows or heifers - Farm and Dairy". Farm and Dairy. Retrieved December 27, 2017.
Jump up ^ Klaus-Dieter Budras, et al, Bovine Anatomy: An Illustrated Text (2003), p. 36.
Jump up ^ "Muley". The Free Dictionary. Retrieved December 27, 2017.
Jump up ^ TIM TRAINOR Montana Standard (2010-04-28). "Example of large steer". Missoulian.com. Retrieved 2012-08-06.
Jump up ^ "A P Carter, P D P Wood and Penelope A Wright (1980), Association between scrotal circumference, live weight and sperm output in cattle, Journal of Reproductive Fertility, 59, pp 447–451" (PDF). Retrieved 2012-08-06.
Jump up ^ "G Jayawardhana (2006), Testicle Size – A Fertility Indicator in Bulls, Australian Government Agnote K44" (PDF). Northern Territory of Australian. Agnote. Archived from the original (PDF) on May 28, 2016. Retrieved 10 January 2018.
Jump up ^ Sarkar, A. (2003). Sexual Behaviour In Animals. Discovery Publishing House. ISBN 978-81-7141-746-9.
Jump up ^ Functional Anatomy and Physiology of Domestic Animals – William O. Reece – Google Boeken. Books.google.com. 2009-03-04. ISBN 978-0-8138-1451-3. Retrieved 2012-12-02.
Jump up ^ Modern Livestock and Poultry Production – James R. Gillespie, Frank B. Flanders – Google Boeken. Books.google.com. 2009-01-28. ISBN 1-4283-1808-9. Retrieved 2012-12-02.
Jump up ^ Fubini, Susan L; Ducharme, Norm (2004-01-15). "Farm Animal Surgery". ISBN 1-4160-6465-6.
Jump up ^ Price, Edward O (2008). "Principles and Applications of Domestic Animal Behavior: An Introductory Text". ISBN 978-1-78064-055-6.
Jump up ^ Practical Atlas of Ruminant and Camelid Reproductive Ultrasonography. Books.google.com. 2009-09-24. Retrieved 2013-06-22.
Jump up ^ Cattle Medicine – Philip R. Scott, Colin D. Penny, Alastair Macrae. Books.google.com. 2011-07-15. Retrieved 2013-06-30.
Jump up ^ Reproductive Pathology of Domestic Mammals – Mark McEntee. Books.google.com. 1990-08-28. Retrieved 2013-06-30.
Jump up ^ Clinical Examination of Farm Animals – Peter Jackson, Peter Cockcroft. Books.google.com. 2008-04-15. Retrieved 2013-06-30.
^ Jump up to: a b Heide Schatten; Gheorghe M. Constantinescu (21 March 2008). Comparative Reproductive Biology. John Wiley & Sons. ISBN 978-0-470-39025-2.
Jump up ^ "Longhorn_Information – handling". ITLA. Archived from the original on 2010-05-11. Retrieved 2010-03-28.
^ Jump up to: a b Castration of Calves Factsheet, Ontario Ministry of Agriculture, June 2007.
Jump up ^ "Frame scoring of beef cattle". New South Wales Government. Department of Primary Industries. 13 September 2007. Retrieved 10 January 2018.
Jump up ^ "Handling Livestock Successfully" (PDF). Canadian Farming Administration. 2000. Archived from the original (PDF) on March 12, 2016. Retrieved 10 January 2018.
Jump up ^ "Larry D. Jacobson, Extension Agricultural Engineer, Safe Work Practices on Dairy Farms, University of Minnesota Extension Services (1989)". University of Minnesota - Extension. www.extension.umn.edu. Archived from the original on July 12, 2013. Retrieved 10 January 2018. During the last 10 years, 12 farmers in Minnesota were mauled and gored to death by dairy bulls
Jump up ^ Cumberland County (Pa.) Sentinel, Shippensburg, Pa., February 12, 2008 A farmer in Southampton County, Michigan, was killed by a 2000 pound Holstein bull in Cumberland County, Pennsylvania, in February, 2008.[dead link]
Jump up ^ The Reading [Pennsylvania]Eagle, March 1, 2010 On February 28, 2010, a farmer near Reading, Pennsylvania was trampled and gored to death by a 2000 lb. black Angus bull that he had been urged to get rid of by friends after earlier mishaps. Michelle Park, "Bull attacks, kills owner at South Heidelberg Township farm".
Jump up ^ Alvin H. Clement, We Gotta Have More Jails, The Writer's Club Press, New York (1984–87), at pp. 79-80. A humorous description of moving a cow to a neighbor's Jersey bull for breeding purposes, and the use of a 12-foot bull staff to get the loose-running bull under control after he had already spotted the cow
Jump up ^ O.C. Gregg, Ed., Minnesota Farmer's Institute Annual No. 15, Pioneer Press, St. Paul, Minn. (1902), at p. 125; The James Way, The James Manufacturing Co., Ft. Atkinson, Wisc. (1914), p. 103.
Jump up ^ Helpful Information for Dairymen, The Farmer, Webb Publishing Co., St. Paul, Minnesota, Mar. 12, 1927, p. 6
Jump up ^ Todaro, Giovanni (1 January 2014). "The man-eater of GÃ©vaudan". Google Books. Lulu.com. Retrieved 10 January 2018.
Jump up ^ U.S. Dept. of Agriculture, Yearbook 1922, Government Printing Office, Washington D.C. (1922), pp. 325-28 (noting a national on-farm bull population of over 600,000 "scrub" bulls in addition to a multi-year supply of "pure bred" bulls)
Jump up ^ O.C. Gregg, Ed., Minnesota Farmer's Institute Annual No. 15, Pioneer Press, St. Paul, Minn. (1902), pp.129-32 (recommending the keeping and testing of sires for dairy herd improvement).
Jump up ^ C. J. C. Phillips, Principles of Cattle Production (2010), p. 121.
Jump up ^ "John C Barret (1991), "The Economic Role of Cattle in Communal Farming Systems in Zimbabwe", to be published in Zimbabwe Veterinary Journal, p 10" (PDF). Retrieved 2012-08-06.
Jump up ^ "Draught Animal Power, an Overview, Agricultural Engineering Branch, Agricultural Support Systems Division, Food and Agriculture Organisation of the United Nations". Fiat Panis. Archived from the original on July 1, 2010. Retrieved 10 January 2018.
Jump up ^ Capretto, Lisa (10 June 2014). "The Unusual Pet That Upset Charo's Neighbors (Video)". Huffington Post. Retrieved 10 January 2018.
External links[edit]
Look up bull in Wiktionary, the free dictionary.
Quotations related to Bull at Wikiquote
Media related to Bulls at Wikimedia Commons
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Geography of Spain
From Wikipedia, the free encyclopedia
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Geography of Spain
Continent
Europe
Region
Southern Europe
Iberian Peninsula
Coordinates
1,917.8 km (1,191.7 mi)
Portugal:
1,214 km (754 mi)
France:
623 km (387 mi)
Andorra:
63.7 km (39.6 mi)
Morocco (Melilla):
9.6 km (5.97 mi)
Morocco (Ceuta):
6.3 km (3.91 mi)
Gibraltar:
1.2 km (0.75 mi)
Highest point
Teide (Canary Islands)
3,718 m (12,198 ft)
Mulhacén (Iberian Peninsula)
3,477 m (11,407 ft)
Lowest point
Atlantic Ocean, Mediterranean Sea
0 m (0 ft) (Sea level)
Longest river
Tagus
Largest lake
Lago de Sanabria
Map of Spain and Portugal, Corrected and Augmented from the Map Published by D. Tomas Lopez. 1810.
Spain is a country located in southwestern Europe occupying most (about 85 percent) of the Iberian Peninsula and includes a small exclave inside France called Llívia as well as the Balearic Islands in the Mediterranean, the Canary Islands in the Atlantic Ocean 108 km (67 mi) off northwest Africa, and five places of sovereignty (plazas de soberanía) on and off the coast of North Africa: Ceuta, Melilla, Islas Chafarinas, Peñón de Alhucemas, and Peñón de Vélez de la Gomera.
The Spanish mainland is bordered to the south and east almost entirely by the Mediterranean Sea (except for a small land boundary with Gibraltar); to the north by France, Andorra, and the Bay of Biscay; and to the west by the Atlantic Ocean and Portugal. With an area of 504,030 km2, Spain is the largest country in Southern Europe, the second largest country in Western Europe (behind France) and the fourth largest country in the European continent (behind Russia, Ukraine and France). It has an average altitude of 650 m.
Its total area is 504,782 km2 (194,897 sq mi) of which 499,542 km2 (192,874 sq mi) is land and 5,240 km2 (2,023 sq mi) is water.[1] Spain lies between latitudes 36° and 44° N, and longitudes 19° W and 5° E. Its Atlantic coast is 710 km (441 mi) long. The Pyrenees mountain range, extends 435 km (270 mi) from the Mediterranean to the Bay of Biscay. In the extreme south of Spain lie the Straits of Gibraltar, which separate the Iberian peninsula and the rest of Europe from Ceuta and Morocco in North Africa; at its narrowest extent, mainland Spain and Morocco are separated by only 13 km (8.1 mi).
Contents
[hide]
1 External boundaries and landform regions
1.1 The Inner Plateau and associated mountains
1.2 Other mountainous regions
1.3 Lowland regions
1.4 The islands
2 Drainage, floods and water stress
2.1 Floods and erosion
2.2 Water stress
3 Climate
4 Population geography
5 Largest cities by population
5.1 Biggest metropolitan areas
5.2 Islands
6 Resources and land use
7 Environmental concerns
8 Maritime claims
9 See also
10 Notes
11 References
12 External links
External boundaries and landform regions[edit]
Spain's exclaves in north Africa
Hypsometric curve of Spain
Most of Spain's boundaries are water: the Mediterranean Sea on the south to the French border and the Atlantic Ocean on the northwest and southwest (in the south as the Golfo de Cádiz and in the north as the Bay of Biscay). Spain also shares land boundaries with France and Andorra along the Pyrenees in the northeast, with Portugal on the west, and with the small British Overseas Territory of Gibraltar near the southernmost tip. The affiliation of Gibraltar has continued to be a contentious issue between Spain and Britain. The sovereignty of the plazas de soberanía on the Mediterranean coast of Morocco is disputed by Morocco.
Spain also has a small exclave inside France called Llívia.
The majority of Spain's peninsular region consists of the Meseta Central, a highland plateau rimmed and dissected by mountain ranges. Other landforms include narrow coastal plains and some lowland river valleys, the most prominent of which is the Andalusian Plain in the southwest. The country can be divided into ten natural regions or subregions: the dominant Meseta Central, the Cantabrian Mountains (Cordillera Cantabrica) and the northwest region, the Ibérico region, the Pyrenees, the Penibético region in the southeast, the Andalusian Plain, the Ebro Basin, the coastal plains, the Balearic Islands, and the Canary Islands. These are commonly grouped into four types: the Meseta Central and associated mountains, other mountainous regions, lowland regions, and islands.
The Inner Plateau and associated mountains[edit]
The Meseta Central ("Inner Plateau") is a vast plateau in the heart of peninsular Spain, which has elevations that range from 610 to 760 m. Rimmed by mountains, the Meseta Central slopes gently to the west and to the series of rivers that form some of the border with Portugal. The Sistema Central, described as the "dorsal spine" of the Meseta Central, divides the Meseta into northern and southern subregions, the former higher in elevation and smaller in area than the latter. The Sistema Central rims the capital city of Madrid with peaks that rise to over 2,400 m within the Madrid region. South-west of Madrid, the Sistema Central shows its highest peak, Pico Almanzor, of 2,592 m. The mountains of the Sistema Central, which continue westward into Portugal, display some glacial features; the highest of the peaks are snow-capped for most of the year. Despite their height, however, the mountain system does not create a major barrier between the northern and the southern portions of the Meseta Central because several passes permit road and railroad transportation to the northwest and the northeast.
The southern portion of the Meseta (Spanish: Submeseta Sur) is further divided by twin mountain ranges, the Montes de Toledo running to the east with the Sierra de Guadalupe, to the west. Their peaks do not rise much higher than 1,500 m. With many easy passes, including those that connect the Meseta with the Andalusian Plain, the Montes de Toledo do not present an obstacle to transportation and communication. This chain of lower mountain ranges is separated from the Sistema Central to the north by the longest river in the Iberian Peninsula: the Tagus River.
The Picos de Europa in Northern Spain
The mountain regions that rim the Meseta Central and are associated with it are the Sierra Morena, the Cordillera Cantábrica, and the Sistema Ibérico. Forming the southern edge of the Meseta Central, the Sierra Morena merges in the east with the southern extension of the Sistema Iberico and reaches westward along the northern edge of the Rio Guadalquivir valley to join the mountains in southern Portugal. The massif of the Sierra Morena extends northward to the Río Guadiana, which separates it from the Sistema Central. Despite their relatively low elevations, seldom surpassing 1,300 m, the mountains of the Sierra Morena are rugged at their southern edge.
The Cordillera Cantábrica, a limestone formation, runs parallel to, and close to, the northern coast near the Bay of Biscay. Its highest points are the Picos de Europa, surpassing 2,600 m. The Cordillera Cantábrica extends 182 km and abruptly drops 1,500 m some 30 km from the coast. To the west lie the hills of the northwest region and to the east the Basque mountains that link them to the Pyrenees.
The Sistema Ibérico extends from the Cordillera Cantábrica southeastward and, close to the Mediterranean, spreads out from the Río Ebro to the Río Júcar. The barren, rugged slopes of this mountain range cover an area of close to 21,000 square kilometers. The mountains exceed 2,000 m in their northern region and reach a maximum height of over 2,300 m east of the headwaters of the Rio Duero. The extremely steep mountain slopes in this range are often cut by deep, narrow gorges.
Other mountainous regions[edit]
External to the Meseta Central lie the Pyrenees in the northeast and the Sistema Penibético in the southeast. The Pyrenees, extending from the eastern edge of the Cordillera Cantábrica to the Mediterranean Sea, form a solid barrier that separates Spain, France and Andorra and has acted as a natural border throughout history, which has effectively isolated the countries from each other. Passage is easy in the relatively low terrain at the eastern and western extremes of the mountain range; it is here that international railroads and roadways cross the border. In the central section of the Pyrenees, however, passage is difficult. In several places, peaks rise above 3,000 m; the highest, Pico de Aneto, surpasses 3,400 m.
The Sistema Penibético extends northeast from the southern tip of Spain, running parallel to the coast until it merges with the southern extension of the Sistema Ibérico near the Rio Júcar and with the eastern extension of the Sierra Morena. The Sierra Nevada, part of the Sistema Penibético south of Granada, includes the highest mountain on the peninsula and continental Spain, Mulhacén, which rises to 3,479 m. Other peaks in the range also surpass 3,000 m.
Lowland regions[edit]
The major lowland regions are the Andalusian Plain in the southwest, the Ebro Basin in the northeast, and the coastal plains. The Andalusian Plain is essentially a wide river valley through which the Río Guadalquivir flows. The river broadens out along its course, reaching its widest point at the Golfo de Cadiz. The Andalusian Plain is bounded on the north by the Sierra Morena and on the south by the Sistema Penibético; it narrows to an apex in the east where these two mountain chains meet. The Ebro Basin is formed by the Río Ebro valley, contained by mountains on three sides—the Sistema Ibérico to the south and west, the Pyrenees to the north and east, and their coastal extensions paralleling the shore to the east. Minor low-lying river valleys close to the Portuguese border are located on the Tagus and the Río Guadiana.
The Coastal Plains regions are narrow strips between the coastal mountains and the seas. They are broadest along the Golfo de Cádiz, where the coastal plain adjoins the Andalusian Plain, and along the southern and central eastern coasts. The narrowest coastal plain runs along the Bay of Biscay, where the Cordillera Cantábrica ends close to shore.
Teide, the highest mountain in Spain (Tenerife, Canary Islands)
The islands[edit]
The remaining regions of Spain are the Balearic and the Canary Islands, the former located in the Mediterranean Sea and the latter in the Atlantic Ocean. The Balearic Islands, encompassing a total area of 5,000 square kilometers, lie 80 kilometers off Spain's central eastern coast. The mountains that rise up above the Mediterranean Sea to form these islands are an extension of the Sistema Penibetico. The archipelago's highest points, which reach 1,400 meters, are in northwestern Mallorca, close to the coast. The central portion of Majorca is a plain, bounded on the east and the southeast by broken hills.
The Canary Islands, ninety kilometers off the west coast of Africa, are of volcanic origin. The large central islands, Tenerife and Gran Canaria, have the highest peaks. Pico de Las Nieves, on Gran Canaria, rises to 1,949 meters, and the Teide, on Tenerife, to 3,718 meters. Teide, a dormant volcano, is the highest peak of Spain and the third largest volcano in the world from its base.
Drainage, floods and water stress[edit]
See also: List of rivers of Spain
River basins of continental Spain
Of the roughly 1,800 rivers and streams in Spain, only the Tagus is more than 960 kilometers long; all but 90 extend less than 96 kilometers. These shorter rivers carry small volumes of water on an irregular basis, and they have seasonally dry river beds; however, when they do flow, they often are swift and torrential. Most major rivers rise in the mountains rimming or dissecting the Meseta Central and flow westward across the plateau through Portugal to empty into the Atlantic Ocean. One significant exception is the river with the most abundant flow in Spain, the Ebro, which flows eastward to the Mediterranean. Rivers in the extreme northwest and in the narrow northern coastal plain drain directly into the Atlantic Ocean. The northwestern coastline is also truncated by rias, waterbodies similar to fjords. {{[2]citation needed|date=October 2015}}
The major rivers flowing westward through the Meseta Central include the Duero, the Tagus, the Guadiana, and the Guadalquivir. The Rio Guadalquivir is one of the most significant rivers in Spain because it irrigates a fertile valley, thus creating a rich agricultural area, and because it is navigable inland, making Seville the only inland river port for ocean-going traffic in Spain. The major river in the northwest region is the Miño.[citation needed]
El Atazar Dam is a major dam built near Madrid to provide a water supply.
Floods and erosion[edit]
Santa Teresa flood.
Certain Spanish regions can be considered vulnerable to both flooding and erosion.[3]
15 October 1879, in Murcia, Santa Teresa flood.
13–15
October 1957, in Valencia, torrential rain results in a devastating flood, at least 81 people lost their lives.[4]

In 1982, the river Jucar (Valencia, Spain) broke the Tous Reservoir causing a flood that killed 30 people.[5]
Water stress[edit]
See also: Water abstraction
Water stress or water lack, poses the greatest threat in Spain. Water scarcity is a significant issue in many regions throughout Spain and climate change may aggravate the problem, with longer periods of dry weather. Supply problems regularly occur in the Jucar basin during summer. In the Segura basin, water scarcity has resulted in an increase of the water prices by 30% for households. Overall, the regions in the south-east of Spain are particularly vulnerable to water shortages. Furthermore, large areas of the Mediterranean are affected by saltwater intrusion.[3]
Climate[edit]
Main article: Climate of Spain
The Mediterranean coast of Spain
Three main climatic zones can be separated, according to geographical situation and orographic conditions:[6][7][8][9]
The Mediterranean climate, characterized by dry and warm summers. According to the Köppen climate classification, it is dominant in the peninsula, with two varieties: Csa and Csb.
The semiarid climate (Bsh, Bsk), located in the southeastern quarter of the country, especially in the region of Murcia and in the Ebro valley. In contrast with the Mediterranean climate, the dry season extends beyond the summer.
The oceanic climate (Cfb), is located in the northern quarter of the country, especially in the regions of Basque Country, Asturias, Cantabria and partly Galicia. In contrary to the Mediterranean climate, winter and summer temperatures are influenced by the ocean.
Apart from these main types, other sub-types can be found, like the desertic climate in parts of southeastern Spain, like in coastal Almería. Humid continental, alpine and tundra climates in the Pyrenees and Sierra Nevada, and a typical subtropical climate in the Canary Islands, varying from humid subtropical climates to desertic climates in most of the islands, and a tropical hot semi-arid climate in coastal parts, such as Tenerife or Gran Canaria.
Population geography[edit]
Main article: Demographics of Spain
Spain's cities and main towns
Largest cities by population[edit]
Madrid 3,300,000
Barcelona 1,582,738
Valencia 797,654 [1]
Seville 709,975
Zaragoza 626,081
Málaga 547,105
Murcia 391,146
Las Palmas 377,600
Palma 367,277
Bilbao 353,567
Valladolid 321,143
Córdoba 318,628
Alicante 305,911
Vigo 292,576
Gijón 270,875
Hospitalet de Llobregat 246,415
A Coruña (Corunna) 243,902
Granada 237,663
Vitoria-Gasteiz 223,257
Santa Cruz de Tenerife 220,022
Badalona 214,440
Oviedo 207,699
Elche 207,163
Móstoles 201,789
Terrassa 200,000
Pamplona 198,750
Biggest metropolitan areas[edit]
Main metropolitan areas in Spain
The largest metropolitan areas, based on 2007 population, were:[10]
Madrid 5,603,285
Barcelona 4,667,136
Valencia 1,671,189
Sevilla 1,294,081
Bilbao 950,829
Málaga 897,563
Asturias (Gijón-Oviedo) 857,079
Alicante-Elche 748,565
Zaragoza 731,803
Vigo 662,412
Las Palmas 616,903
Bahía de Cádiz (Cádiz-Jerez de la Frontera) 615,494
Santa Cruz de Tenerife 573,825
Murcia 563,272
Palma de Mallorca 474,035
Granada 472,638
San Sebastián 402,168
Tarragona 406,042
A Coruña 403,007
Valladolid 400,400
Santander - Torrelavega 391,480
Cordoba 323,600
Pamplona 309,631
Further information: List of metropolitan areas in Spain by population
Islands[edit]
Islander population:[11]
1. Tenerife 886.033
2. Mallorca 846.210
3. Gran Canaria 829.597
4. Lanzarote 132.366
5. Ibiza 113.908
6. Fuerteventura 94.386
7. Menorca 86.697
8. La Palma 85.933
9. La Gomera 22.259
10. El Hierro 10.558
11. Formentera 7.957
12. Arousa 4.889
13. La Graciosa 658
14. Tabarca 105
15. Ons 61
Resources and land use[edit]
Natural resources: coal, lignite, iron ore, uranium, mercury, pyrites, fluorspar, gypsum, zinc, lead, tungsten, copper, kaolin, potash, sepiolite, hydropower, arable land
Land use:
Arable land: 27.18%
Permanent crops: 9.85%
Other: 62.97% (2005)
Irrigated land: 38,000 km2 (2003)
Total renewable water resources: 111.1 cubic metres (2005)
Freshwater withdrawal (domestic/industrial/agricultural):
total: 37.22 cu km/yr (13%/19%/68%)
per capita: 864 cu m/yr (2002)
Environmental concerns[edit]
Natural hazards: periodic droughts, occasional flooding
Environment – Current Issues:
Pollution of the Mediterranean Sea from raw sewage and effluents from the offshore production of oil and gas; water quality and quantity nationwide; air pollution; deforestation; desertification
Environment – International Agreements:
Party to: Air Pollution, Air Pollution-Nitrogen Oxides, Air Pollution-Sulphur 94, Air Pollution-Volatile Organic Compounds, Antarctic-Environmental Protocol, Antarctic Treaty, Biodiversity, Climate Change, Climate Change-Kyoto Protocol, Desertification, Endangered Species, Environmental Modification, Hazardous Wastes, Law of the Sea, Marine Dumping, Marine Life Conservation, Ozone Layer Protection, Ship Pollution, Tropical Timber 83, Tropical Timber 94, Wetlands, Whaling
Signed, but not ratified: Air Pollution-Persistent Organic Pollutants
Maritime claims[edit]
contiguous zone: 24 nmi (44.4 km; 27.6 mi)
exclusive economic zone: 200 nmi (370.4 km; 230.2 mi) (applies only to the Atlantic Ocean)
territorial sea: 12 nmi (22.2 km; 13.8 mi)
See also[edit]
Autonomous communities of Spain
Comarcas of Spain
Extreme points of Spain
Provinces of Spain
Notes[edit]
Jump up ^ "Spain". The World Factbook. Central Intelligence Agency. 2008. Retrieved 2008-12-09.
Jump up ^ "Spain - Rivers". countrystudies.us. Retrieved 2017-10-05.
^ Jump up to: a b http://ec.europa.eu/maritimeaffairs/documentation/studies/documents/spain_en.pdf
Jump up ^ Hasta aquí llegó la riada, ABC, 13 August 2007
Jump up ^ Diluvio en el País Valenciano, La Vanguardia, 21 October 1982, p1
Jump up ^ "Atlas Climático Ibérico – Iberian Climate Atlas" (PDF). 2011. Retrieved 2011-10-18. Agencia Estatal de Meteorología © (Espana). Ministerio de Medio Ambiente y Medio Rural y Marino © (Espana). Instituto de Meteorologia de Portugal ©.
Jump up ^ "World Map of the Köppen-Geiger climate classification updated – (see p.3)" (PDF). Retrieved 2011-04-30.
Jump up ^ http://www.city-data.com/forum/attachments/weather/56180d1263187925-ultimate-climate-poll-koppen-climate-classification-kottek_et_al_2006.gif
Jump up ^ "Archived copy". Archived from the original on April 30, 2011. Retrieved January 1, 2013.
Jump up ^ Ruiz, Francisco (2007). "Población de las áreas urbanas y metropolitanas". Población de España – datos y mapas (in Spanish). Alarcos Research Group. Archived from the original (xls) on February 3, 2009. Retrieved 2008-12-10.
Jump up ^ La superficie de las islas vendrá dada en hectáreas salvo la de las mayores islas de los archipiélagos canario y balear, así como las Plazas de Soberanía.
References[edit]
This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. (June 2012) (Learn how and when to remove this template message)
This article incorporates public domain material from the Library of Congress Country Studies website http://lcweb2.loc.gov/frd/cs/.
This article incorporates public domain material from the CIA World Factbook website https://www.cia.gov/library/publications/the-world-factbook/index.html.
External links[edit]
Loyd, Nick (2007). "IberiaNature: A guide to the environment, climate, wildlife, geography and nature of Spain". Retrieved 2008-12-04.
Data Spain: Satellite relief maps, aerial photography, outline maps, travel maps and useful themed maps of Spain
Virtual Cadastral: Lookup official Spanish property (catastro) deeds and other Spanish property information: exact map location, altitude, land area, and distances.
Coordinates: 40°00′N 4°00′W / 40.000°N 4.000°W / 40.000; -4.000
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Multilayer perceptron
From Wikipedia, the free encyclopedia
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"MLP" is not to be confused with "NLP", which refers to natural language processing.
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A multilayer perceptron (MLP) is a class of feedforward artificial neural network. An MLP consists of at least three layers of nodes. Except for the input nodes, each node is a neuron that uses a nonlinear activation function. MLP utilizes a supervised learning technique called backpropagation for training.[1][2] Its multiple layers and non-linear activation distinguish MLP from a linear perceptron. It can distinguish data that is not linearly separable.[3]
Multilayer perceptrons are sometimes colloquially referred to as "vanilla" neural networks, especially when they have a single hidden layer.[4]
Contents
[hide]
1 Theory
1.1 Activation function
1.2 Layers
1.3 Learning
2 Terminology
3 Applications
4 References
5 External links
Theory[edit]
Activation function[edit]
If a multilayer perceptron has a linear activation function in all neurons, that is, a linear function that maps the weighted inputs to the output of each neuron, then linear algebra shows that any number of layers can be reduced to a two-layer input-output model. In MLPs some neurons use a nonlinear activation function that was developed to model the frequency of action potentials, or firing, of biological neurons.
The two common activation functions are both sigmoids, and are described by
y ( v i ) = tanh  ( v i ) and y ( v i ) = ( 1 + e − v i ) − 1 {\displaystyle y(v_{i})=\tanh(v_{i})~~{\textrm {and}}~~y(v_{i})=(1+e^{-v_{i}})^{-1}} .
The first is a hyperbolic tangent that ranges from -1 to 1, while the other is the logistic function, which is similar in shape but ranges from 0 to 1. Here y i {\displaystyle y_{i}} is the output of the i {\displaystyle i} th node (neuron) and v i {\displaystyle v_{i}} is the weighted sum of the input connections. Alternative activation functions have been proposed, including the rectifier and softplus functions. More specialized activation functions include radial basis functions (used in radial basis networks, another class of supervised neural network models).
Layers[edit]
The MLP consists of three or more layers (an input and an output layer with one or more hidden layers) of nonlinearly-activating nodes making it a deep neural network. Since MLPs are fully connected, each node in one layer connects with a certain weight w i j {\displaystyle w_{ij}} to every node in the following layer.
Learning[edit]
Learning occurs in the perceptron by changing connection weights after each piece of data is processed, based on the amount of error in the output compared to the expected result. This is an example of supervised learning, and is carried out through backpropagation, a generalization of the least mean squares algorithm in the linear perceptron.
We represent the error in output node j {\displaystyle j} in the n {\displaystyle n} th data point (training example) by e j ( n ) = d j ( n ) − y j ( n ) {\displaystyle e_{j}(n)=d_{j}(n)-y_{j}(n)} , where d {\displaystyle d} is the target value and y {\displaystyle y} is the value produced by the perceptron. The node weights are adjusted based on corrections that minimize the error in the entire output, given by
E ( n ) = 1 2 ∑ j e j 2 ( n ) {\displaystyle {\mathcal {E}}(n)={\frac {1}{2}}\sum _{j}e_{j}^{2}(n)} .
Using gradient descent, the change in each weight is
Δ w j i ( n ) = − η ∂ E ( n ) ∂ v j ( n ) y i ( n ) {\displaystyle \Delta w_{ji}(n)=-\eta {\frac {\partial {\mathcal {E}}(n)}{\partial v_{j}(n)}}y_{i}(n)}
where y i {\displaystyle y_{i}} is the output of the previous neuron and η {\displaystyle \eta } is the learning rate, which is selected to ensure that the weights quickly converge to a response, without oscillations.
The derivative to be calculated depends on the induced local field v j {\displaystyle v_{j}} , which itself varies. It is easy to prove that for an output node this derivative can be simplified to
− ∂ E ( n ) ∂ v j ( n ) = e j ( n ) ϕ ′ ( v j ( n ) ) {\displaystyle -{\frac {\partial {\mathcal {E}}(n)}{\partial v_{j}(n)}}=e_{j}(n)\phi ^{\prime }(v_{j}(n))}
where ϕ ′ {\displaystyle \phi ^{\prime }} is the derivative of the activation function described above, which itself does not vary. The analysis is more difficult for the change in weights to a hidden node, but it can be shown that the relevant derivative is
− ∂ E ( n ) ∂ v j ( n ) = ϕ ′ ( v j ( n ) ) ∑ k − ∂ E ( n ) ∂ v k ( n ) w k j ( n ) {\displaystyle -{\frac {\partial {\mathcal {E}}(n)}{\partial v_{j}(n)}}=\phi ^{\prime }(v_{j}(n))\sum _{k}-{\frac {\partial {\mathcal {E}}(n)}{\partial v_{k}(n)}}w_{kj}(n)} .
This depends on the change in weights of the k {\displaystyle k} th nodes, which represent the output layer. So to change the hidden layer weights, the output layer weights change according to the derivative of the activation function, and so this algorithm represents a backpropagation of the activation function.[5]

Terminology[edit]
The term "multilayer perceptron" does not refer to a single perceptron that has multiple layers. Rather, it contains many perceptrons that are organized into layers. An alternative is "multilayer perceptron network". Moreover, MLP "perceptrons" are not perceptrons in the strictest possible sense. True perceptrons are formally a special case of artificial neurons that use a threshold activation function such as the Heaviside step function. MLP perceptrons can employ arbitrary activation functions. A true perceptron performs binary classification (either this or that), an MLP neuron is free to either perform classification or regression, depending upon its activation function.
The term "multilayer perceptron" later was applied without respect to nature of the nodes/layers, which can be composed of arbitrarily defined artificial neurons, and not perceptrons specifically. This interpretation avoids the loosening of the definition of "perceptron" to mean an artificial neuron in general.
Applications[edit]
MLPs are useful in research for their ability to solve problems stochastically, which often allows approximate solutions for extremely complex problems like fitness approximation.
MLPs are universal function approximators as showed by Cybenko's theorem,[3] so they can be used to create mathematical models by regression analysis. As classification is a particular case of regression when the response variable is categorical, MLPs make good classifier algorithms.
MLPs were a popular machine learning solution in the 1980s, finding applications in diverse fields such as speech recognition, image recognition, and machine translation software,[6] but thereafter faced strong competition from much simpler (and related[7]) support vector machines. Interest in backpropagation networks returned due to the successes of deep learning.
References[edit]
Jump up ^ Rosenblatt, Frank. x. Principles of Neurodynamics: Perceptrons and the Theory of Brain Mechanisms. Spartan Books, Washington DC, 1961
Jump up ^ Rumelhart, David E., Geoffrey E. Hinton, and R. J. Williams. "Learning Internal Representations by Error Propagation". David E. Rumelhart, James L. McClelland, and the PDP research group. (editors), Parallel distributed processing: Explorations in the microstructure of cognition, Volume 1: Foundation. MIT Press, 1986.
^ Jump up to: a b Cybenko, G. 1989. Approximation by superpositions of a sigmoidal function Mathematics of Control, Signals, and Systems, 2(4), 303–314.
Jump up ^ Hastie, Trevor. Tibshirani, Robert. Friedman, Jerome. The Elements of Statistical Learning: Data Mining, Inference, and Prediction. Springer, New York, NY, 2009.
Jump up ^ Haykin, Simon (1998). Neural Networks: A Comprehensive Foundation (2 ed.). Prentice Hall. ISBN 0-13-273350-1.
Jump up ^ Neural networks. II. What are they and why is everybody so interested in them now?; Wasserman, P.D.; Schwartz, T.; Page(s): 10-15; IEEE Expert, 1988, Volume 3, Issue 1
Jump up ^ R. Collobert and S. Bengio (2004). Links between Perceptrons, MLPs and SVMs. Proc. Int'l Conf. on Machine Learning (ICML).
External links[edit]
A Gentle Introduction to Backpropagation - An intuitive tutorial by Shashi Sathyanarayana This is an updated PDF version of a blog article that was previously linked here. This article contains pseudocode ("Training Wheels for Training Neural Networks") for implementing the algorithm.
Weka: Open source data mining software with multilayer perceptron implementation.
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