click links in text for more info
SUMMARY / RELATED TOPICS

Morphogenesis

Morphogenesis is the biological process that causes an organism to develop its shape. It is one of three fundamental aspects of developmental biology along with the control of cell growth and cellular differentiation, unified in evolutionary developmental biology; the process controls the organized spatial distribution of cells during the embryonic development of an organism. Morphogenesis can take place in a mature organism, in cell culture or inside tumor cell masses. Morphogenesis describes the development of unicellular life forms that do not have an embryonic stage in their life cycle, or describes the evolution of a body structure within a taxonomic group. Morphogenetic responses may be induced in organisms by hormones, by environmental chemicals ranging from substances produced by other organisms to toxic chemicals or radionuclides released as pollutants, other plants, or by mechanical stresses induced by spatial patterning of the cells; some of the earliest ideas and mathematical descriptions on how physical processes and constraints affect biological growth, hence natural patterns such as the spirals of phyllotaxis, were written by D'Arcy Wentworth Thompson in his 1917 book On Growth and Form and Alan Turing in his The Chemical Basis of Morphogenesis.

Where Thompson explained animal body shapes as being created by varying rates of growth in different directions, for instance to create the spiral shell of a snail, Turing predicted a mechanism of morphogenesis, the diffusion of two different chemical signals, one activating and one deactivating growth, to set up patterns of development, decades before the formation of such patterns was observed. The fuller understanding of the mechanisms involved in actual organisms required the discovery of the structure of DNA in 1953, the development of molecular biology and biochemistry. Several types of molecules are important in morphogenesis. Morphogens are soluble molecules that can diffuse and carry signals that control cell differentiation via concentration gradients. Morphogens act through binding to specific protein receptors. An important class of molecules involved in morphogenesis are transcription factor proteins that determine the fate of cells by interacting with DNA; these can be coded for by master regulatory genes, either activate or deactivate the transcription of other genes.

At the end of this cascade are classes of molecules that control cellular behaviors such as cell migration, or, more their properties, such as cell adhesion or cell contractility. For example, during gastrulation, clumps of stem cells switch off their cell-to-cell adhesion, become migratory, take up new positions within an embryo where they again activate specific cell adhesion proteins and form new tissues and organs. Developmental signaling pathways implicated in morphogenesis include Wnt and ephrins. At a tissue level, ignoring the means of control, morphogenesis arises because of cellular proliferation and motility. Morphogenesis involves changes in the cellular structure or how cells interact in tissues; these changes can result in tissue elongation, folding, invasion or separation of one tissue into distinct layers. The latter case is referred as cell sorting. Cell "sorting out" consists of cells moving so as to sort into clusters that maximize contact between cells of the same type; the ability of cells to do this has been proposed to arise from differential cell adhesion by Malcolm Steinberg through his differential adhesion hypothesis.

Tissue separation can occur via more dramatic cellular differentiation events during which epithelial cells become mesenchymal. Mesenchymal cells leave the epithelial tissue as a consequence of changes in cell adhesive and contractile properties. Following epithelial-mesenchymal transition, cells can migrate away from an epithelium and associate with other similar cells in a new location. In plants, cellular morphogenesis is linked to the chemical composition and the mechanical properties of the cell wall. During embryonic development, cells are restricted to different layers due to differential affinities. One of the ways this can occur is. For instance, homotypic cell adhesion can maintain boundaries between groups of cells that have different adhesion molecules. Furthermore, cells can sort based upon differences in adhesion between the cells, so two populations of cells with different levels of the same adhesion molecule can sort out. In cell culture cells that have the strongest adhesion move to the center of a mixed aggregates of cells.

Moreover, cell-cell adhesion is modulated by cell contractility, which can exert forces on the cell-cell contacts so that two cell populations with equal levels of the same adhesion molecule can sort out. The molecules responsible for adhesion are called cell adhesion molecules. Several types of cell adhesion molecules are known and one major class of these molecules are cadherins. There are dozens of different cadherins. Cadherins bind to other cadherins in a like-to-like manner: E-cadherin binds preferentially to other E-cadherin molecules. Mesenchymal cells express other cadherin types such as N-cadherin; the extracellular matrix is involved in keeping tissues separated, providing structural support or providing a structure for cells to migrate on. Collagen and fibronectin are major ECM molecules

LinkBike

LinkBike is a public bicycle sharing system serving the city of George Town in Penang, Malaysia. Launched in 2016, it is the first such system in Malaysia. There are 250 LinkBike bicycles and 25 stations throughout the city, including its UNESCO World Heritage Site, as well as suburban places like Queensbay Mall. LinkBike, jointly funded by the Penang Island City Council and Fast Rent Bike Sdn. Bhd, a local private limited firm, is part of the wider efforts undertaken by the Penang state government to alleviate traffic congestion within George Town, as well as to promote environmentally-friendly alternative transportation modes. In August 2016, the Chief Minister of Penang, Lim Guan Eng, announced the planned public bicycle sharing service within George Town; the proposed system, an internet of things -based initiative of the Penang Island City Council, is to be operated on a public-owned and managed model. Of the RM1.85 million allocated to run the service, 90% was to be borne by the Penang Island City Council, while Fast Rent Bike, which contributed the remaining 10% of the cost, would operate the system.

LinkBike was launched on 17 December 2016, with nine stations within George Town and an initial fleet of 60 bicycles. Not only is LinkBike the first public bicycle sharing system in Malaysia, it made George Town the first city in Malaysia to operate such a system. LinkBike's fleet was enlarged to 250 bicycles by April 2017. Since its launch, LinkBike recorded a ridership figure of 3,422 as of 11 April 2017; this figure rose to 8,583 by 28 May. LinkBike has been expanded to 25 stations scattered throughout George Town, covering various destinations between Gurney Drive to the north and Queensbay Mall, near Bayan Lepas, to the south. LinkBike utilises two electronic rental payment methods - the smart card and the smartphone application; the smartphone app is designed as a QR code scanner and comes with a location-based GPS feature that indicates the nearest LinkBike stations, as well as the number of available bicycles at any particular station updated in real time. Meanwhile, LinkBike's smart card can be topped up using either cash or credit card at LinkBike's office at the Esplanade.

Each LinkBike bicycle has been fitted with an LED-powered dynamo hub that lights up the bicycle's front and rear once motion is detected. The first 30 minutes of each ride is free-of-charge, after which a fee of RM1 is imposed for every subsequent hour. Users can purchase daily, monthly or annual passes, ranging from RM2 for 24 hours to RM30 for a one-year pass; as of August 2017, 25 LinkBike stations have been installed within and around George Town, including 12 throughout the city's UNESCO World Heritage Site. Each station has either 12 bicycle parking docks. Cycling in Penang Island List of bicycle-sharing systems LinkBike

Schlumberger

Schlumberger is an international oilfield services company. Schlumberger employs 100,000 people representing more than 140 nationalities working in more than 120 countries. Schlumberger has four principal executive offices located in Paris, Houston and The Hague. Schlumberger is incorporated in Willemstad, Curaçao as Schlumberger N. V. and trades on the New York Stock Exchange, Euronext Paris, the London Stock Exchange and SIX Swiss Exchange. Schlumberger is a Fortune Global 500 company, ranked 287 in 2016, listed in Forbes Global 2000, ranked 176 in 2016. Schlumberger was founded in 1926 by two brothers Conrad and Marcel Schlumberger from the Alsace region in France as the Electric Prospecting Company; the company recorded the first-ever electrical resistivity well log in Merkwiller-Pechelbronn, France in 1927. Today, Schlumberger supplies the petroleum industry with services such as seismic acquisition and processing, formation evaluation, well testing and directional drilling, well cementing and stimulation, artificial lift, well completions, flow assurance and consulting, software and information management.

The company is involved in the groundwater extraction and carbon capture and storage industries. The Schlumberger brothers had experience conducting geophysical surveys in countries such as Romania, Serbia, South Africa, the Democratic Republic of the Congo and the United States; the new company sold electrical-measurement mapping services, recorded the first-ever electrical resistivity well log in Merkwiller-Pechelbronn, France in 1927. The company expanded, logging its first well in the U. S. in 1929, in Kern County, California. In 1935, the Schlumberger Well Surveying Corporation was founded in Houston evolving into Schlumberger Well Services, Schlumberger Wireline & Testing. Schlumberger invested in research, inaugurating the Schlumberger-Doll Research Center in Ridgefield, Connecticut in 1948, contributing to the development of a number of new logging tools. In 1956, Schlumberger Limited was incorporated as a holding company for all Schlumberger businesses, which by now included American testing and production company Johnston Testers.

Over the years, Schlumberger continued to expand its acquisitions. In 1960, Dowell Schlumberger, which specialized in pumping services for the oil industry, was formed. In 1962, Schlumberger Limited became listed on the New York Stock Exchange; that same year, Schlumberger purchased Daystrom, an electronic instruments manufacturer in South Boston, Virginia, making furniture by the time the division was sold to Sperry & Hutchinson in 1971. Schlumberger purchased 50% of Forex in 1964 and merged it with 50% of Languedocienne to create the Neptune Drilling Company; the first computerized reservoir analysis, SARABAND, was introduced in 1970. The remaining 50% of Forex was acquired the following year. In 1979, Fairchild Camera and Instrument became a subsidiary of Schlumberger Limited. In 1981, Schlumberger established the first international data links with e-mail. In 1983, Schlumberger opened their Cambridge Research Center in Cambridge, England and in 2012 it was renamed the Schlumberger Gould Research Center after the company's former CEO Andrew Gould.

The SEDCO drilling rig company and half of Dowell of North America were acquired in 1984, resulting in the creation of the Anadrill drilling segment, a combination of Dowell and The Analysts' drilling segments. Forex Neptune was merged with SEDCO to create the Sedco Forex Drilling Company the following year, when Schlumberger purchased Merlin and 50% of GECO. In 1987, Schlumberger completed their purchases of Neptune and Cori, Allmess; that same year, National Semiconductor acquired Fairchild Semiconductor from Schlumberger for $122 million. In 1991, Schlumberger acquired PRAKLA-SEISMOS, pioneered the use of geosteering to plan the drill path in horizontal wells. In 1992, Schlumberger acquired software company GeoQuest Systems. With the purchase came the conversion of SINet to TCP/IP and thus internet capable. In the 1990s Schlumberger bought out the petroleum division, AEG meter, ECLIPSE reservoir study team Intera Technologies Corp. A joint venture between Schlumberger and Cable & Wireless resulted with the creation of Omnes, which handled all of Schlumberger's internal IT business.

Oilphase and Camco International were purchased. In 1999, Schlumberger and Smith International created a joint venture, M-I L. L. C; the world's largest drilling fluids company. The company consists of 60% Smith International, 40% Schlumberger. Since the joint venture was prohibited by a 1994 antitrust consent decree barring Smith from selling or combining their fluids business with certain other companies, including Schlumberger, the U. S. District Court in Washington, D. C. found Smith International Inc. and Schlumberger Ltd. guilty of criminal contempt and fined each company $750,000 and placed each company on five years probation. Both companies agreed to pay a total of $13.1 million, representing a full disgorgement of all of the joint venture's profits during the time the companies were in contempt. In 2000, the Geco-Prakla division was merged with Western Geophysical to create the seismic contracting company WesternGeco, of which Schlumberger held a 70% stake, the remaining 30% belonging to competitor Baker Hughes.

Sedco Forex was spun off, merged with Transocean Drilling company in 2000. In 2001, Schlumberger acquired the IT consultancy company Sema plc for $5.2 billion. The company was an Athens 2004 Summer Olympics partner, but Schlumber

Peter Westbury

Peter Westbury was a British racing driver from England. He participated in two World Championship Formula One Grands Prix. In 1969 he raced a Formula 2 Brabham-Cosworth, driving in his first Grand Prix in the 1969 German Grand Prix, he finished ninth on the road, fifth in the F2 class. The following year he failed to qualify for the 1970 United States Grand Prix driving a works BRM, after an engine failure. Early in his racing career he campaigned a homebuilt special called the M. G. W. Graduating to a Cooper-Climax in 1960, fitted with a Daimler V8 engine. Westbury won the British Hill Climb Championship twice, in 1963 and 1964. In 1963 he drove the self-built Felday, with supercharged Daimler V8 2.6-litre motor. The following year he won in the 2.5-litre Climax-engined Ferguson P99 with four-wheel-drive, on loan from Ferguson Research Ltd. Westbury drove the Ferguson P99 in the 1964 Brighton Speed Trials and at the First International Drag Festival, a series of six events held in England that year, where the car covered the standing-start quarter mile in 11.01 seconds.

He drove a Lotus 23-BRM sports car at the Drag Festival. During 1965 Westbury developed the Felday-BRM 4 sports car with four-wheel-drive; the car won on its debut at Brands Hatch on 26 December 1965, driven by Mac Daghorn. At Mallory Park on 13 March 1966, Peter Westbury and Mac Daghorn shared the car, each winning a race. Jim Clark raced the Felday 4 in the Guards Trophy at Brands Hatch on 29 August 1966; the Felday 5 sports car was fitted with a 7-litre Ford Galaxie engine and four wheel drive, but only raced briefly. The Felday 6 was a 4.7-litre Ford-powered hillclimb single-seater, with rear wheel drive, built for Tony Griffiths. In 1967 Westbury raced a Brabham-Ford Formula Three car in Continental Europe, he won the F3 race at the Silverstone circuit on 29 April, the Grand Prix des Frontières at Chimay on 14 May, at the Auvergne Trophy meeting on 18 June 1967, on the daunting Clermont-Ferrand circuit in France. The same year he resuscitated the old BRM P67 four-wheel-drive F1 car, designed by Mike Pilbeam in 1964, for David Good to campaign in the British Hill Climb Championship.

The car led the series at the half-way mark, but passed into the hands of Peter Lawson, who revamped it for 1968. The car was a dominant winner of the series in 1968

Skullyville County, Choctaw Nation

Skullyville County was a political subdivision of the Choctaw Nation of Indian Territory, prior to Oklahoma being admitted as a state. The county formed part of the Nation's Moshulatubbee District, or First District, one of three administrative super-regions; the county was called Iskvlli Kaunti, from the Choctaw word iskvlli, which means a “small piece of money or coin.” Skullyville County was home, from 1832, of the United States agency for the Choctaws in the Indian Territory. The agency was located about fifteen miles west of Fort Smith; the village which grew up around the agency came to be known as Skullyville, that word being a corruption of “iskulli” with the suffix, “ville,” suggesting a literal translation of “money town.” The agency itself, was called Iskvlli ai Ilhpita, or “the place where money is donated or presented.” Skullyville town was settled in about 1832, after the area served as a landing site for Choctaw Indians who came to the new Indian Territory via the “Trail of Tears" by steamboat.

The steamboats used a landing on the south side of the Arkansas River featuring a large rock shelf. The town served as county seat, it served as one-time capital of the Choctaw Nation. Fort Coffee was built and garrisoned by the U. S. Army in 1834 to secure the region from incursions by the “wild” Wichita and Comanche Indians to the west. Skullyville was visited the same year by George Catlin, an American painter and traveler, who specialized in portraits of Native Americans in the old West. Catlin painted Choctaw Indians playing stickball at Skullyville, provides the only surviving descriptions of the Ball Play Dance and Eagle Dance. Catlin depicts the stickball game in a valley framed by the rolling hills which are iconic to the Skullyville region. Skullyville County was one of the original 19 counties created by the General Council of the Choctaw Nation in 1850; the county's boundaries were established and designated according to recognizable natural landmarks, as were the boundaries of all Choctaw Nation counties.

As example, the Arkansas River formed the county's northern border. The Arkansas state line formed the eastern border; the western border was a line drawn from the mouth of Cashier Creek on the Arkansas River southeard to its source. From there it followed a straight line to an area known near Red Oak; the county's southern border threaded its way through well-defined valleys along Cavanal Mountain and adjacent ridges, following Cedar Creek, Fourche Maline, the Poteau River. The county served as an election district for members of the National Council, as a unit of local administration. Constitutional officers, all of whom served for two-year terms and were elected by the voters, included the county judge, a ranger; the judge's duties included oversight of overall county administration. The sheriff collected taxes, monitored unlawful intrusion by intruders, conducted the census; the county ranger sold strayed livestock. As Oklahoma's statehood approached, its leading citizens, who were gathered for the Oklahoma Constitutional Convention, realized in laying out the future state's counties that, while logically designed, the Choctaw Nation's counties could not exist as economically viable political subdivisions.

In most the county seat existed for holding county court and not as a population center. While this was not true of Skullyville County, with its bustling commercial towns along several railroad lines, Poteau, it would have to be dismantled in order to accommodate changes required by the region at large; this conundrum was recognized by the framers of the proposed State of Sequoyah, who met in 1905 to propose statehood for the Indian Territory. The Sequoyah Constitutional Convention proposed a county structure that abolished the Choctaw counties. Skullyville County was divided principally into the proposed Thomas Rutherford County. Stigler and Bokoshe would have been Thomas County's principal towns; the prosperous railroad junctions of Poteau and Wister would have anchored Rutherford County. None of this proposition was borrowed two years by Oklahoma's framers, who adopted a different county structure for the region; the territory comprising Skullyville County, Choctaw Nation now falls within Le Flore and Latimer counties.

Skullyville County ceased to exist upon Oklahoma's statehood on November 16, 1907

Consumer choice

The theory of consumer choice is the branch of microeconomics that relates preferences to consumption expenditures and to consumer demand curves. It analyzes how consumers maximize the desirability of their consumption as measured by their preferences subject to limitations on their expenditures, by maximizing utility subject to a consumer budget constraint. Consumption is separated from production, because two different economic agents are involved. In the first case consumption is by the primary individual. Therefore, different motivations and abilities are involved; the models that make up consumer theory are used to represent prospectively observable demand patterns for an individual buyer on the hypothesis of constrained optimization. Prominent variables used to explain the rate at which the good is purchased are the price per unit of that good, prices of related goods, wealth of the consumer; the law of demand states that the rate of consumption falls as the price of the good rises when the consumer is monetarily compensated for the effect of the higher price.

As the price of a good rises, consumers will substitute away from that good, choosing more of other alternatives. If no compensation for the price rise occurs, as is usual the decline in overall purchasing power due to the price rise leads, for most goods, to a further decline in the quantity demanded. In addition, as the wealth of the individual rises, demand for most products increases, shifting the demand curve higher at all possible prices; the basic problem of consumer theory takes the following inputs: The consumption set C – the set of all bundles that the consumer could conceivably consume. A preference relation over the bundles of C; this preference relation can be described as an ordinal utility function, describing the utility that the consumer derives from each bundle. A price system, a function assigning a price to each bundle. An initial endowment, a bundle from C that the consumer holds; the consumer can sell all or some of his initial bundle in the given prices, can buy another bundle in the given prices.

He has to decide which bundle to buy, under the given prices and budget, in order to maximize his utility. Consider an economy with two types of homogeneous divisible goods, traditionally called X and Y; the consumption set is R + 2, i.e. the set of all pairs where x ≥ 0 and y ≥ 0. Each bundle contains a non-negative quantity of good X and a non-negative quantity of good Y. A typical preference relation in this universe can be represented by a set of indifference curves; each curve represents a set of bundles. A typical utility function is the Cobb–Douglas function: u = x α ⋅ y β, whose indifference curves look like in the figure below. A typical price system assigns a price to each type of good, such that the cost of bundle is x p X + y p Y. A typical initial endowment is just a fixed income, which along with the prices implies a budget constraint; the consumer can choose any point below the budget constraint line BC In the diagram. This line is downward sloped and linear since it represents the boundary of the inequality x p X + y p Y ≤ i n c o m e.

In other words, the amount spent on both goods together is less than or equal to the income of the consumer. The consumer will choose the indifference curve with the highest utility, attainable within his budget constraint; every point on indifference curve I3 is outside his budget constraint so the best that he can do is the single point on I2 where the latter is tangent to his budget constraint. He will purchase X* of good X and Y* of good Y. Indifference curve analysis begins with the utility function; the utility function is treated as an index of utility. All, necessary is that the utility index change as more preferred bundles are consumed. Indifference curves are numbered with the number increasing as more preferred bundles are consumed; the numbers have no cardinal significance. Income effect and price effect deal with how the change in price of a commodity changes the consumption of the good; the theory of consumer choice examines the trade-offs and decisions people make in their role as consumers as prices and their income changes.

As a second example, consider an economy which consists of a large land-estate L. The consumption set is P, i.e. the set of all subsets of L. A typical preference relation in this universe can be represented by a utility function which assigns, to each land parcel, its total "fertility" (the total amount of grain that can be grown i