The facts about Mercury

Mercury is the in close proximity planet to the Sun and the eighth biggest. Mercury is somewhat slighter in diameter than the moons Ganymede and Titan but more than twice as enormous.

Mercury's orbit is exceptionally eccentric; at perihelion it is just 46 million km from the Sun but at aphelion it is 70 million. The position of the perihelion processes regarding the Sun at a very slow rate. 19th century astronomers made extremely careful explanation of Mercury's orbital parameters but could not sufficiently explain those using Newtonian mechanics. The tiny differences between the experimental and predicted values were a slight but nagging problem for many decades. It was thought that one more planet (sometimes called Vulcan) slightly nearer to the Sun than Mercury power account for the discrepancy. But in spite of much effort, no such planet was found. The real reply turned out to be much more dramatic: Einstein's General Theory of Relativity! Its right forecast of the motions of Mercury was a main factor in the early acceptance of the theory.

Vehicle

The Trikke is a Human mechanical Vehicle (HPV) This article is about the means of transport. For additional uses see Vehicle (disambiguation).

Vehicles are lifeless means of transportation. They are nearly everyone often man-made (e.g. bicycles, cars, motorcycles, trains, ships, and aircraft), although some other means of transportation which are not made by man can also be called vehicles; examples include icebergs and floating tree trunks.

Vehicles possibly will be propelled by animals, e.g. a chariot or an ox-cart. However, animals on their own, although used as a means of transportation, are not called vehicles. This includes humans carrying another human, for example a child or a disabled person.

Vehicles that do not voyage on land are often called crafts, such as watercraft, sailcraft, aircraft, hovercraft and spacecraft.

Most land vehicles contain wheels. Please observe the wheel article for examples of vehicles with and without wheels.

Movement without the rally round of a vehicle or an animal is called locomotion. The word vehicle itself comes starting the Latin vehiculum

Abstract art

Abstract art is now typically understood to mean art that does not depict objects in the natural world, but instead uses color and form in a non-representational way. In the very near the beginning 20th century, the term was more often used to describe art, such as Cubist and Futurist art, that depicts real forms in a simplified or rather reduced way—keeping only an allusion of the original natural subject. Such paintings were often claimed to capture astonishing of the depicted objects' immutable intrinsic qualities rather than its external appearance. The additional precise terms, "non-figurative art," "non-objective art," and "non-representational art" keep away from any possible ambiguity.

Bay of Bengal

The Bay of Bengal is a cove that forms the northeastern ingredient of the Indian Ocean. It resembles a triangle in form, and is enclosed on the east by Malay Peninsula, and on the west by India. On the northern pour of the "bay" lies the Bengal region, comprising the Indian state of West Bengal and the country of Bangladesh, thus the name. The southern boundaries arrive at the island country of Sri Lanka, and the Indian Union Territory of Andaman and Nicobar Islands.

The Bay of Bengal occupies a region of 2,172,000 km². It is bordered by India and Sri Lanka to the West, Bangladesh to the North, and Myanmar and the southern division of Thailand to the East. Its southern border extends as an imaginary line from Dondra Head at the southern end of Sri Lanka to the northern angle of Sumatra. A number of huge rivers – Ganges, Brahmaputra, Irrawaddy, Godavari, Mahanadi, Krishna and Cauvery – run into the Bay of Bengal. Among the vital ports are Yangon, Kolkata/Calcutta, Chittagong, Cuddalore, Kakinada, Machlipatnam, Madras, Paradip and Vishakapatnam.

Salad

Salad is a light meal — or, as part of a bigger meal, much more of an taster — consisting of varied vegetables (usually including at least one leaf vegetable) or fruit, frequently with a dressing or sauce, occasionally nuts and sometimes with the addition of meat, fish or cheese. It is usually seen as a healthy dish, even though not always low in calories, salt, sugar, or fat because of the dressing that is often added. The word "salad" comes from the French salade of the identical meaning, which in twist is from the Latin salata, "salty", from sal, "salt".

Traffic light

A traffic light or traffic signal is a signalling device positioned at a road junction or pedestrian crossing to indicate when it is safe to drive, ride or walk, using a universal color code.Traffic lights for usual vehicles or pedestrians always have two main lights, a red one that means stop and a green one that means go. Generally, the red light contains some orange in its hue, and the green light contains some blue, to provide some support for people with red-green color blindness. In most countries there is also a yellow (or amber) light, which when on and not flashing means stop if able to do so securely. In some systems, a flashing amber means that a motorist may go in advance with care if the road is clear, giving way to pedestrians and to other road vehicles that may have precedence. A flashing red effectively means the same as a regular stop sign. There may be additional lights (usually a green arrow or "filter") to allow turns (called a lead light in the U.S., because it is usually leading the main green light).

Present Battery Electric Vehicles

At the present time, disagreement reign over battery electric vehicles. Campaigners, (et al) for BEV's are reproving three major US automobile manufacturers of deliberately sabotaging BEV efforts through more than a few methods, for instance, failing to market, failing to produce appropriate vehicles, by failing to satisfy demand and using lease-only programs with prohibitions against end of lease purchase.

In their defense, the three major manufacturers they have responded that they only create what the public want and the recent trend is that the public doesn't want battery electric vehicles.Although we have the technology to manufacture and provide BEVs, one of the largest downfalls for the prolific production of BEVs is the extortionate cost of replacement batteries. In some cases the cost of stand-in batteries can be more than the price of the whole vehicle, especially when buying used battery electric vehicles.

Electric vehicles in 1959

In 1959 the Henney Kilowatt was introduced and was the world's initial modern transistor-regulated electric car and the predecessor to the more recent battery electric vehicles such as General Motors EV1. Only 47 Henney Kilowatts were created, 24 being sold as 1959 models and 8 as 1960 models. It is not clear what happened to the other 15 built but it could be probable that they were sold as 1961 or 1962 models. None of the 8 1960 models were sold in the direction of the public because of the high manufacturing costs, but were sold to the electric cooperatives who funded the project.

It is estimated that there are connecting four and eight Henney Kilowatt battery electric vehicles still in existence with at least two of the survivors still driven at times.

Battery electric vehicles had issues with high battery costs, with restricted travel distances, with charging time and the lifespan of the battery, although advancements in battery technology has addressed a lot of those problems.

Battery in1913 to 1947

One of the downfalls of the battery electric vehicle was the opening of the electric starter in 1913. It easy the task of starting an internal combustion engine which was previously hard and dangerous to start with the crank handle. Another was the mass-produced and somewhat cheap Ford Model-T. Finally, the loss of Edisons through present electric power transmission system. He was battling with George Westinghouse and Nikola Tesla over their desire to introduce alternating present as the principal electricity distribution. Edison's direct current was the weight for electric motors.

Battery electric vehicles were limited to position applications. Forklift trucks were battery exciting vehicles when introduced in 1923. BEV golf carts which were used as locality electric vehicles and were partially "street legal". By the late 1930s, the electric automobile business had disappeared until the invention of the point contact transistor in 1947 which started a new era of electric vehicle.

History of Battery Electric Vehicles in 1900

Prior to 1900, battery electric vehicles held many speed and distance records, the most famous of which, was the breaking of the 100 km/h (60 mph) speed barrier. It was by Camille Jenatzy on April 29, 1899 in a rocket-shaped vehicle named Jamais Contente (Never Happy) which reached a peak speed of 105.88 km/h (65.79 mph).

During the early 20th Century, battery electric vehicles outsold gasoline powered vehicles and were successfully sold as city cars to upper-class customers. Because of high technological limitations, these cars were limited to a peak speed of about 32 km/h (20 mph). The cars were marketed as "appropriate vehicles for women drivers". Electric vehicles did not need hand-cranking to launch.

The History of Battery Electric Vehicles

Battery exciting Vehicles or BEVs, predated the Internal Combustion Engine (ICE) vehicles. It was between 1832-1839 that Robert Anderson, a Scottish businessman, imaginary the first electric carriage and Professor Sibrandus Stratingh from the Netherlands designed the first small-scale electric car which was built by his assistant Christopher Becker in 1835.

The storage battery better, firstly by Gaston Plant, a French physicist who invented the guide acid cell in 1859 and the first rechargeable battery. Then, in 1881, Camille Faure residential a more efficient and reliable battery which became so successful in the early electric cars. This discovery caused battery electric vehicles to flourish, with France and Great Britain being the first nations to support prevalent development of electric vehicles.

Battery
A battery is a device consisting of one or more electrochemical cells, which store chemical energy and make it accessible in an electrical form. There are many types of electrochemical cells, together with galvanic cells, electrolytic cells, fuel cells, flow cells, and voltaic cells. Formally, an electrical "battery" is an array of similar voltaic cells ("cells") joined in series. However, in many contexts it is universal to call a single cell a battery. A battery's individuality may vary due to many factors including internal chemistry, current drain, and temperature. Generally, battery life can be prolonged by storing the battery in a cool place and using it at an appropriate current.

Although an early form of battery may have been used in ancient times, the development of modern batteries started with the Voltaic pile, invented by the Italian physicist Alessandro Volta in 1800. Since then, batteries have gained recognition as they became portable and useful for many purposes. Unfortunately, the well-known use of batteries has created many environmental concerns, such as toxic metal pollution. Many reclamation companies reprocess batteries to reduce the number of batteries going into landfills. Rechargeable batteries can be charged hundreds of times before draining out; and even after wearing out they can be recycled.

There are two types of batteries disposable and rechargeable both of which convert chemical energy to electrical energy. Disposable batteries can only be used once because they use up their chemicals in an irreversible reaction. Rechargeable batteries can be recharged because the chemical reactions they use are reversible; they are recharged by running a charging current through the battery, but in the opposite direction of the discharge current.

Transistor radio

The transistor radio is a small radio receiver.RCA established a prototype transistor radio in 1952. The first profitable transistor radio, the Regency TR-1, was announced on October 18, 1954 by the Regency Division of Industrial Development Engineering Associates of Indianapolis, Indiana and put on sale in November of 1954. It cost $49.95 (the equivalent of $361 in year-2005 dollars) and sold approximately 100,000 units.

The structure of pollen


Each pollen grain contain vegetative cells only one in the greater part flowering plant but several in other seed plants and a generative cell contain a tube nucleus that produces the pollen tube and a generative nucleus that divide to form the two sperm cells. The group of cells is surrounded by a cellulose cell wall and a thick, rough outer wall made of sporopollenin.

Pollen is created in the microsporangium contained in the anther of an angiosperm flower, male cone of a coniferous plant, or male cone of other seed plants. Pollen grains come in a broad multiplicity of shapes, sizes, and surface markings characteristic of the species see photomicrograph at right. Most, but surely not all, are spherical, Pollen grains of pines, firs, and spruces are wing. The minimum pollen grain that of the Forget-me-not plant (Myosotis sp.), is approximately 6 µm (0.006 mm) in diameter.

Pollen grains may have furrows, the course of which classify the pollen as colpate or sulcate. The number of furrows or pores helps categorize the flowering plants, with eudicots having three colpi (tricolpate), and other groups having one sulcus.

Earth's atmosphere

Earth's atmosphere is a layer of gases surrounding the planet Earth and retain by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide; trace amounts of other gases, and a changeable amount (average around 1%) of water vapor. This mixture of gases is usually known as air. The atmosphere protects life on Earth by captivating ultraviolet solar radiation and reducing temperature extremes between day and night.

There is no exact border between the atmosphere and outer space, it slowly becomes thinner and fades into liberty. Three quarters of the atmosphere's mass is within 11 km of the terrestrial surface. In the United States, people who travel above a height of 80.5 km (50 statute miles) are selected astronauts. An altitude of 120 km (400,000 ft) marks the boundary where atmospheric property becomes obvious during re-entry. The Kármán line, at 100 km (328,000 ft), is also often regarded as the boundary between atmosphere and outer space.

whaleboat

A whaleboat is a type of open boat that is comparatively narrow and pointed at both ends, enabling it to move either forwards or backwards equally well. It was initially developed for whaling, and later became popular for work along beaches, as it does not need to be turned around for beaching or refloating.
Whaleboats are usually oar-powered, although in whaling use often had a dismountable mast and sails, too. After 1850 most were fitted with a centerboard for marine. When sailing, steering was with a rudder; when rowing, navigation was done with an oar held over the stern. Whaleboats used in whaling had a stout post mounted on the aft deck, approximately which the steersman would cinch the rope once the whale had been harpooned, and by which the whale would drag the boat awaiting it was killed.
The term "whaleboat" may be used casually of larger whalers, or of a boat used for whale watching.

Carrot

The carrot (Daucus carota subsp. sativus) is a root vegetable, usually orange or white, or pink in color, with a crunchy texture when fresh. The suitable for eating part of a carrot is a taproot. It is a cultivated form of the wild carrot Daucus carota, national to Europe and southwestern Asia. It has been bred for its very much inflamed and more palatable, less woody-textured edible taproot, but is still the similar species.

It is a biennial plant which grows a rosette of leaves in the spring and summer, while building up the fat taproot, which stores big amounts of sugars for the plant to flower in the second year. The peak stem grows to about 1 m tall, with an umbel of white flowers.

Carrots can be eaten raw, whole, chopped, grate, or added to salads for color or texture. They are also often chopped and boiled, fried or steamed, and cooked in soups and stews, as well as fine baby foods and choose pet foods. A well recognized dish is carrots julienne. Grated carrots are used in carrot cakes, as healthy as carrot puddings, an old English dish thought to have originated in the early 1800s.

Tajmahal

The Taj Mahal is a mausoleum situated in Agra, India. The Mughal Emperor ShahJahan commissioned it as a mausoleum for his favorite’s wife, Mumtaz Mahal. Building began in 1632 and was completed in 1648. Some argument surrounds the question of who designed the Taj; it is clear a team of designers and craftsmen were in charge for the design, with Ustad Isa carefully the most likely candidate as the main designer.
The Taj Mahal sometimes called "the Taj is generally known as the finest example of Mughal architecture, a style that combines elements of Persian and Indian. While the white domed marble mausoleum is the most memorable part of the monument, the Taj Mahal is actually an included complex of structures. It was planned as a UNESCO World Heritage Site in 1983 when it was described as universally admired masterpieces of the world's heritage.

Chef's uniform

The conventional chef's uniform, including toque (traditional hat), white double breasted jacket, and checked pants are immediately recognized by most members of the Western world, especially in this day of television's celebrity chefs. The double breasted jacket can be inverted to conceal stains. Its thick cotton cloth protects from the heat of stove and oven and protects from splattering of steaming liquids. An apron is an obviously useful piece of utensils used to guard the rest of the wearer's garments from food splatters and stains.

The toque (chef's hat) dates back to the 16th century when hats were regular in many businesses. Different heights of hats point out rank within a kitchen. Some modern chefs have put their own diverse whirl on the traditional uniform. But the traditional, practical, clothing of the chef still remainders a standard in the food industry.

Public transport

Public transport, public transportation, public travel or mass transit comprises all transport systems in which the passengers do not tour in their own vehicles. While it is generally taken to include rail and bus services, wider definitions would comprise scheduled airline services, ship, taxicab services etc. – any system that transports members of the universal public. A further restriction that is sometimes practical is that it must take place in shared vehicles that would bar taxis that are not shared-ride taxis.

Jewellery and society

Jewellery is factually any piece of fine material used to decorate oneself. Although in earlier times jewellery was created for more convenient uses, such as wealth storage and pinning clothes together, in recent times it has been used almost completely for beautification. The first pieces of jewellery were made from likely materials, such as bone and animal teeth, shell, wood and engraved stone. Jewellery was often made for people of high importance to show their status and, in many cases, they were covered with it.Jewellery is made out of almost every material recognized and has been made to garnish nearly every body part, from hairpins to toe rings and many more types of jewellery. While high-quality and artistic pieces are made with gemstones and valuable metals, less pricey costume jewellery is made from less-valuable materials and is mass-produced. Form and function Kenyan man exhausting tribal beads.

Over time, jewellery has been used for a number of reasons: Currency, wealth display and storage, purposeful Symbolism Protection and Artistic display Most cultures have at some point had a practice of observance large amounts of wealth stored in the form of jewellery. Numerous cultures move wedding dowries in the form of jewelry, or create jewelry as a means to store or display coins. On the other hand, jewellery has been used as a currency or trade good; a mostly poignant example being the use of slave beads.

Feather

Feathers are one of the epidermal growths that shape the distinctive outer covering, or plumage, on birds. They are the outstanding feature that distinguishes the Class Aves from all other living groups. Other Theropoda also had feathers to see feathered dinosaurs.

Characteristics

Feathers are among the most multifaceted structural organs found in vertebrates: integument appendages, formed by controlled explosion of cells in the epidermis, or outer skin layer that produce keratin proteins. The β-keratins in feathers, beaks and claws — and the claws, scales and shells of reptiles — are calm of protein strands hydrogen-bonded into β-pleated sheets, which are then further twisted and cross linked by disulfide bridges into structures even tougher than the α-keratins of mammalian hair, horns and hoof.
Feathers are one of the epidermal growths that shape the distinctive outer covering, or plumage, on birds. They are the outstanding feature that distinguishes the Class Aves from all other living groups. Other Theropoda also had feathers to see feathered dinosaurs.

Camera

A camera is a device used to take pictures, either alone or in series, with or without sound, such as with video cameras. The name is resulting from camera obscura, Latin for dark chamber, an early mechanism for projecting images in which an whole room functioned much as the internal workings of a modern photographic camera, except there was no way at this time to record the image little of physically tracing it. Cameras may work with the chart spectrum or other portions of the electromagnetic spectrum.

Every camera consists of a number of enclosed chambers, with an opening or aperture at one end for light to go into, a recording or viewing surface for capturing the light at the other conclusion. This diameter of the aperture is often forbidden by a diaphragm mechanism, but some cameras have a fixed-size opening.

Video and digital cameras use electronics, frequently a charge coupled device or sometimes a CMOS sensor to detain images which can be transfer or stored in tape or computer memory within the camera for later playback or processing. Traditional cameras capture glow onto photographic film or photographic plate.

Software tools


Software tools for distributed processing include standard APIs such as MPI and PVM, and open source-based software solutions such as Beowulf and openMosix which make easy the creation of a supercomputer from a collection of ordinary workstations or servers. Technology like ZeroConf (Rendezvous/Bonjour) can be used to make ad hoc computer clusters to for specialized software such as Apple's shake compositing application. An easy programming language for supercomputers leftovers an open research topic in computer science.

Pirogue

A pirogue is a small, flat-botomed boat of a design associated mainly with West African fishermen and the Cajuns of the Louisiana marsh. These boats are not typically intended for over-night travel but are light and small sufficient to be easily taken onto land. The design also allows the pirogue to move through very shallow water and be simply turned over to drain any water that may get into the boat. The pirogue's motion comes from paddles that contain one blade (as opposed to a kayak paddle, which has two). It can also be punted with a pole in low water.
There is not one pirogue plan, are several. Besides small pirogues as seen on the picture, there are also pirogues that can hold up to ten men with paddles and also characteristic a main sail. These are not planned (and should not be used) for open waters. They are only (and best) used close to shore.

Junk

A junk is a Chinese marine vessel. The English name comes from Malay dugong or jong. Junks were initially developed during the Han Dynasty (220 BC-200 AD) and further evolved to symbolize one of the most successful ship types in history.
The organization and flexibility of junk sails make the junk easy to sail, and fast. Unlike a conventional square rigged ship the sails of a junk can be moved inward, toward the long axis of the ship, allow the junk to sail into the wind.
The sails include more than a few horizontal members ("battens") which provide shape and strength. -The sails can also be easily reefed and familiar for fullness, to accommodate various wind strengths. The battens also make the sails more resistant than traditional sails to large tears, as a tear is naturally limited to a single "panel" between battens. Junk sails have much in common with the most aerodynamically well-organized sails used today in windsurfers or catamarans, although their design can be traced back as early the 3rd century AD.
The standing chains are simple or absent. The sail-plan is also extending out between multiple masts, allowing for a powerful sail surface, and a good repartition of efforts, an innovation adopted in the West around 1304. [Citation needed] The rig allows for good marine into the wind.

Kerala houseboats

The houseboats in Kerala, south India, are huge, slow-moving, foreign barges used for leisure trips. They are a reworked model of Kettuvallams (in the Malayalam language, Kettu means "tied with ropes", and vallam means "boat"), which, in earlier times, were used to carry rice and spices from Kuttanad to the Kochi port. Kerala houseboats were measured a suitable means of transportation.
The fame of Kettuvalloms has returned in the function as major tourist attractions. Many come across the Kettuvallom an ideal means of explore the beauty of the Kerala backwaters.
Such a houseboat is about 60 to 70 feet (about 18 to 21 meters) long and concerning 15 feet (about 5 meters) wide at the middle. The hull is made of wooden planks that are detained together by ropes of coconut fiber; the usual wood is 'Anjili'. The roof is completed with bamboo poles and palm leaves. The exterior of the boat is tinted with protective coats of cashew nut oil.

Cigarette boat

The cigarette boat or go-fast boat is a high performance boat of a feature design. Originally designed for his offshore racing team by Donald Aronow, the fast, powerful boats became infamous as the drug smuggling boat of choice in many parts of the world in the 1990s and first years of the 21st century.
In harmony with their pure racing heritage, the accommodations on these boats are minimal, and they are built to hold 5 or more passengers. While most do have some cabin under the foredeck, it is low and much smaller than a characteristic motor yacht of similar size. Apart from the racing market, most buyers of these boats purchase them for the mystique; the mixture of the racing and smuggling connections, plus the immense power and high top speeds make these boats popular as ostentatious displays of wealth.
These boats are hard to detect by radar except on flat calm seas or at close range. The United States Coast Guard and the DEA establish them to be stealthy, fast, seaworthy, and very complicated to intercept using conventional craft. Because of this, Coast Guards contain developed their own high-speed craft and also use helicopters. The helicopters are prepared with Anti-materiel rifles which can be used to disable the motors of the go-fast boat. The Coast Guard go-fast boat is a rigid hulled inflatable boat RHIB ready with radar and powerful engines. The RHIB is armed with quite a few types of non-lethal weapons and M240 GPMG.

Spiral escalators

Spiral escalators acquire less horizontal space than straight escalators. However, in the early spiral designs were failures. For example, one spiral escalator constructed by Reno in combination with William Henry Aston and Scott Kietzman at London's Holloway Road Underground position in 1906 was dismantled almost right away and little of the mechanism survives. The Mitsubishi Electric Corporation has urbanized successful commercial designs and has contrived curved and spiral escalators since the 1980s.
Notable sets of spiral escalators are situated in the Westfield San Francisco Centre in San Francisco, California, and at Forum Shops at Caesars Palace in Las Vegas, Nevada. The Times Square shopping mall in Causeway Bay, Hong Kong, also features four curved escalators, as do Wheelock Place in Singapore.

A simple Girl
Around and around it soared in brutal circles, tearing from side to side her animated temples. At a standstill, they did not do anything. Still, they simply laid there with faces of chalk, invalid of all human emotions. She could not look at them in hopes of relieve, for long. The cherry rivers that flowed across her eyes, streamed down her steaming cheeks, made vision impossible.
Life was simply the stack of decayed flesh that enclosed her. From his immortal lips hung the bodies of all those who died struggle for him and all those who had tampered with self luxury. For that, she dammed him for all eternity; in every form he understood she dammed him. He had been her guiding angle and now it became evident to her. No prayer would pass her conditions lips, for this had been his movement she had fought and they had lost other than just a clash.

Barge

A barge is a flat-bottomed boat, built mostly for river and canal transport of important goods. Most barges are not self-propelled and need to be moved by tugboats towing or towboats pushing them. Barges on inland waterways (towed by draft animals on an adjacent towpath) contended with the railway in the early industrial revolution but were out competed in the carriage of high value items owing to the higher speed, falling costs, and route elasticity of rail transport.
Barges are still used today for low value bulk items, as the cost of hauling goods by barge is very low. Barges are also used for very weighty or bulky items; a typical barge events 195 feet by 35 feet (59.4 meters by 10.6 meters), and can take up to 1500 tons of cargo.

Lotion

A lotion is a low- to medium-viscosity medicated or non-medicated topical preparation intended for application to unbroken skin. Most lotions are oil-in-water emulsions but water-in-oil lotions are also formulated. Lotions are usually applied to external skin with a clean cloth, cotton wool or gauze. The key components of a lotion emulsion are the aqueous and oily phases, an emulgent to prevent separation of these two phases, and, if used, the drug substance or substances. A wide variety of other ingredients such as fragrances, glycerol, dyes, preservatives, vitamins, proteins and stabilizing agents are commonly added to lotions.

It is not uncommon for the same drug ingredient to be formulated into a lotion, cream and ointment. Creams are the most convenient of the three but are inappropriate for application to regions of hairy skin such as the scalp, while a lotion is less viscous and may be readily applied to these areas. Lotions also have an advantage in that they may be spread thinly compared to a cream or ointment and may economically cover a large area of skin. Non-comedogenic lotions are recommended for use on acne prone skin.

Unusual Twinnings

There are some patterns of twinning that are exceedingly rare: while they have been reported to happen, they are so unusual that most obstetricians or midwives may go their entire careers without encountering a single case. Among fraternal twins, in rare cases, the eggs are fertilized at different times with two or more acts of sexual intercourse, either within one menstrual cycle or, even more rarely, later on in the pregnancy. This can lead to the possibility of a woman carrying fraternal twins with different fathers. This phenomenon is known as heteropaternal super fecundation. One 1992 study estimates that the frequency of heteropaternal super fecundation among dizygotic twins whose parents were involved in paternity suits was approximately 2.4%; see the references section, below, for more details.

Among monozygotic twins, in extremely rare cases, twins have been born with opposite sexes. The probability of this is so vanishingly small that multiples having different genders are universally accepted as a sound basis for a clinical determination that in utero multiples are not monozygotic. When monozygotic twins are born with different genders it is because of chromosomal birth defects. In this case, although the twins did come from the same egg, it is incorrect to refer to them as genetically identical, since they have different karyotypes.

Biodiversity

Biodiversity or biological diversity is the diversity of life. There are a number of definitions and a measure of biodiversity. Biodiversity has no single standard definition. The most basic definition is "variation of life at all level of biological organization". Another definition holds that biodiversity is a measure of the relative diversity among organisms present in diverse ecosystems. "Diversity" in this definition includes diversity within a species and among species, and comparative diversity among ecosystems.

A third definition that is often used by ecologists is the "totality of genes, species, and ecosystems of a region". An advantage of this description is that it seems to describe most circumstances and present a unified view of the traditional three levels at which biodiversity has been identified.

The 1992 United Nations Earth Summit in Rio de Janeiro defined "biodiversity" as "the changeability among living organisms from all sources, including, 'inter alia', terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems".