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top 10 words in brain distribution (in article): engine cell energy gas produce type speed air form drive |
top 10 words in brain distribution (in article): light produce time power common state design bulb allow require |
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top 10 words in brain distribution (not in article): vehicle fuel wheel car power gear design aircraft wear horse |
top 10 words in brain distribution (not in article): animal drink lamp water wine beer species bottle cat wolf |
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times more probable under ant 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under telephone (words not in the model) | |
| A phylogeny of the extant ant subfamilies. "'Ants'" are social insects of the family "'Formicidae'", and along with the related wasps and bees, they belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. Today, more than 12,000 species are classified with upper estimates of about 14,000 species. They are easily identified by their elbowed antennae and a distinctive node-like structure that forms a slender waist. Ants form colonies that range in size from a few dozen predatory individuals living in small natural cavities to highly organised colonies which may occupy large territories and consist of millions of individuals. These larger colonies consist mostly of sterile wingless females forming castes of "workers", "soldiers", or other specialised groups. Ant colonies also have some fertile males called "drones" and one or more fertile females called "queens". The colonies are sometimes described as superorganisms because ants appear to operate as a unified entity, collectively working together to support the colony. Ants have colonised almost every landmass on Earth. The only places lacking indigenous ants are Antarctica and certain remote or inhospitable islands. Ants thrive in most ecosystems, and may form 15–25% of the terrestrial animal biomass. Their success has been attributed to their social organisation and their ability to modify habitats, tap resources, and defend themselves. Their long co-evolution with other species has led to mimetic, commensal, parasitic, and mutualistic relationships. Ant societies have division of labour, communication between individuals, and an ability to solve complex problems. These parallels with human societies have long been an inspiration and subject of study. Many human cultures make use of ants in cuisine, medication and rituals. Some species are valued in their role as biological pest control agents. However, their ability to exploit resources brings ants into conflict with humans, as they can damage crops and invade buildings. Some species, such as the red imported fire ant, are regarded as invasive species, since they have establish themselves in new areas where they may be accidentally introduced. Taxonomy and evolution. The family Formicidae belongs to the order Hymenoptera, which also includes sawflies, bees and wasps. Ants evolved from a lineage within the vespoid wasps. Phylogenetic analysis suggests that ants arose in the mid-Cretaceous period about 110 to 130 million years ago. After the rise of flowering plants about 100 million years ago they diversified and assumed ecological dominance around 60 million years ago. In 1966, E. O. Wilson and his colleagues identified the fossil remains of an ant ("Sphecomyrma freyi") that lived in the Cretaceous period. The specimen, trapped in amber dating back to more than 80 million years ago, has features of both ants and wasps. "Sphecomyrma" was probably a ground forager but some suggest on the basis of groups such as the Leptanillinae and Martialinae that primitive ants were likely to have been predators under the soil surface. During the Cretaceous period, only a few species of primitive ants ranged widely on the Laurasian super-continent (the northern hemisphere). They were scarce in comparison to other insects, representing about 1% of the insect population. Ants became dominant after adaptive radiation at the beginning of the Tertiary period. By the Oligocene and Miocene ants had come to represent 20–40% of all insects found in major fossil deposits. Of the species that lived in the Eocene epoch, approximately one in ten genera survive to the present. Genera surviving today comprise 56% of the genera in Baltic amber fossils (early Oligocene), and 92% of the genera in Dominican amber fossils (apparently early Miocene). Termites, though sometimes called "white ants", are not ants and belong to the order Isoptera. The termites are actually more closely related to cockroaches and mantids. The fact that ants and termites are both eusocial came about by Convergent evolution. Velvet ants look like large ants, but are wingless female wasps. Etymology. The word "ant" is derived from "ante" of Middle English which is derived from "æmette" and "emmett" of Old English and is related to the Old High German "āmeiza" from which comes "Ameise", the German word for ant. The family name "Formicidae" is derived from the Latin "formīca" ("ant") from which derived Portuguese "formiga", Spanish "hormiga", Romanian "furnică", French "fourmi", etc. Distribution and diversity. Ants are found on all continents except Antarctica and only a few large islands such as Greenland, Iceland, parts of Polynesia and the Hawaiian Islands lack native ant species. Ants occupy a wide range of ecological niches, and are able to exploit a wide range of food resources either as direct or indirect herbivores, predators and scavengers. Most species are omnivorous generalists but a few are specialist feeders. Their ecological dominance may be measured by their biomass, and estimates in different environments suggest that they contribute 15–20% (on average and nearly 25% in the tropics) of the total terrestrial animal biomass, which exceeds that of the vertebrates. Ants range in size from. Their colours vary; most are red or black, green is less common, and some tropical species have a metallic lustre. More than 12,000 species are currently known (with upper estimates of about 14,000), with the greatest diversity in the tropics. Taxonomic studies continue to resolve the classification and systematics of ants. Online databases of ant species, including AntBase and the Hymenoptera Name Server, help to keep track of the known and newly described species. The relative ease with which ants can be sampled and studied in ecosystems has made them useful as indicator species in biodiversity studies. Morphology. Ants are distinct in their morphology from other insects in having elbowed antennae, metapleural glands, and a strong constriction of their second abdominal segment into a node-like petiole. The head, mesosoma and metasoma or gaster are the three distinct body segments. The petiole forms a narrow waist between their mesosoma (thorax plus the first abdominal segment, which is fused to it) and gaster (abdomen less the abdominal segments in the petiole). The petiole can be formed by one or two nodes (the second alone, or the second and third abdominal segments). Like other insects, ants have an exoskeleton, an external covering that provides a protective casing around the body and a point of attachment for muscles, in contrast to the internal skeletons of humans and other vertebrates. Insects do not have lungs; oxygen and other gases like carbon dioxide pass through their exoskeleton through tiny valves called spiracles. Insects also lack closed blood vessels; instead, they have a long, thin, perforated tube along the top of the body (called the "dorsal aorta") that functions like a heart, and pumps haemolymph towards the head, thus driving the circulation of the internal fluids. The nervous system consists of a ventral nerve cord that runs the length of the body, with several ganglia and branches along the way reaching into the extremities of the appendages. An ant's head contains many sensory organs. Like most insects, ants have compound eyes made from numerous tiny lenses attached together. Ants' eyes are good for acute movement detection but do not give a high resolution. They also have three small ocelli (simple eyes) on the top of the head that detect light levels and polarisation. Compared to vertebrates, most ants have poor-to-mediocre eyesight and a few subterranean species are completely blind. Some ants such as Australia's bulldog ant, however, have exceptional vision. Two antennae ("feelers") are attached to the head; these organs detect chemicals, air currents and vibrations; they are also used to transmit and receive signals through touch. The head has two strong jaws, the mandibles, used to carry food, manipulate objects, construct nests, and for defence. In some species a small pocket (infrabuccal chamber) inside the mouth stores food, so it can be passed to other ants or their larvae. All six legs are attached to the mesosoma ("thorax"). A hooked claw at the end of each leg helps ants to climb and hang onto surfaces. Most queens and male ants have wings; queens shed the wings after the nuptial flight, leaving visible stubs, a distinguishing feature of queens. However, wingless queens (ergatoids) and males occur in a few species. The metasoma (the "abdomen") of the ant houses important internal organs, including those of the reproductive, respiratory (tracheae) and excretory systems. Workers of many species have their egg-laying structures modified into stings that are used for subduing prey and defending their nests. Polymorphism. In the colonies of a few ant species, there are physical castes—workers in distinct size-classes, called minor, median, and major workers. Often the larger ants have disproportionately larger heads, and correspondingly stronger mandibles. Such individuals are sometimes called "soldier" ants because their stronger mandibles make them more effective in fighting, although they are still workers and their "duties" typically do not vary greatly from the minor or median workers. In a few species the median workers are absent, creating a sharp divide between the minors and majors. Weaver ants, for example, have a distinct bimodal size distribution. Some other species show continuous variation in the size of workers. The smallest and largest workers in "Pheidologeton diversus" show nearly a 500-fold difference in their dry-weights. Workers cannot mate; however, because of the haplodiploid sex-determination system in ants, workers of a number of species can lay unfertilised eggs that become fully fertile haploid males. The role of workers may change with their age and in some species, such as honeypot ants, young workers are fed until their gasters are distended, and act as living food storage vessels. These food storage workers are called "repletes". This polymorphism in morphology and behaviour of workers was initially thought to be determined by environmental factors such as nutrition and hormones which led to different developmental paths; however, genetic differences between worker castes have been noted in "Acromyrmex" sp. These polymorphisms are caused by relatively small genetic changes; differences in a single gene of "Solenopsis invicta" can decide whether the colony will have single or multiple queens. The Australian jack jumper ant ("Myrmecia pilosula"), has only a single pair of chromosomes (males have just one chromosome as they are haploid), the lowest number known for any animal, making it an interesting subject for studies in the genetics and developmental biology of social insects. Development and reproduction. The life of an ant starts from an egg. If the egg is fertilised, the progeny will be female (diploid); if not, it will be male (haploid). Ants develop by complete metamorphosis with the larval stages passing through a pupal stage before emerging as an adult. The larva is largely immobile and is fed and cared for by workers. Food is given to the larvae by trophallaxis, a process in which an ant regurgitates liquid food held in its crop. This is also how adults share food, stored in the "social stomach", among themselves. Larvae may also be provided with solid food such as trophic eggs, pieces of prey and seeds brought back by foraging workers and may even be transported directly to captured prey in some species. The larvae grow through a series of moults and enter the pupal stage. The pupa has the appendages free and not fused to the body as in a butterfly pupa. The differentiation into queens and workers (which are both female), and different castes of workers (when they exist), is determined by the nutrition the larvae obtain. Larvae and pupae need to be kept at fairly constant temperatures to ensure proper development, and so are often moved around the various brood chambers within the colony. A new worker spends the first few days of its adult life caring for the queen and young. It then graduates to digging and other nest work, and later to defending the nest and foraging. These changes are sometimes fairly sudden, and define what are called temporal castes. An explanation for the sequence is suggested by the high casualties involved in foraging, making it an acceptable risk only for ants that are older and are likely to die soon of natural causes. Most ant species have a system in which only the queen and breeding females have the ability to mate. Contrary to popular belief, some ant nests have multiple queens while others can exist without queens. Workers with the ability to reproduce are called "gamergates" and colonies that lack queens are then called gamergate colonies; colonies with queens are said to be queen-right. The winged male ants, called drones, emerge from pupae along with the breeding females (although some species, like army ants, have wingless queens), and do nothing in life except eat and mate. During the short breeding period, the reproductives, excluding the colony queen, are carried outside where other colonies of similar species are doing the same. Then, all the winged breeding ants take flight. Mating occurs in flight and the males die shortly afterwards. Females of some species mate with multiple males. Mated females then seek a suitable place to begin a colony. There, they break off their wings and begin to lay and care for eggs. The females store the sperm they obtain during their nuptial flight to selectively fertilise future eggs. The first workers to hatch are weak and smaller than later workers, but they begin to serve the colony immediately. They enlarge the nest, forage for food and care for the other eggs. This is how new colonies start in most species. Species that have multiple queens may have a queen leaving the nest along with some workers to found a colony at a new site, a process akin to swarming in honeybees. Ant colonies can be long-lived. The queens can live | The telephone'" (from the, "tēle", "far" and φωνή, "phōnē", "voice") is a telecommunications device that is used to transmit and receive electronically or digitally encoded sound (most commonly speech) between two or more people conversing. It is one of the most common household appliances in the developed world today. Most telephones operate through transmission of electric signals over a complex telephone network which allows almost any phone user to communicate with almost any other user. Graphic symbols used to designate telephone service or phone-related information in print, signs, and other media include,, and. Basic principle. A traditional landline telephone system, also known as "plain old telephone service" (POTS), commonly handles both signaling and audio information on the same twisted pair of insulated wires: the telephone line. Although originally designed for voice communication, the system has been adapted for data communication such as Telex, Fax and Internet communication. The signaling equipment consists of a bell, beeper, light or other device to alert the user to incoming calls, and number buttons or a rotary dial to enter a telephone number for outgoing calls. A twisted pair line is preferred as it is more effective at rejecting electromagnetic interference (EMI) and crosstalk than an untwisted pair. A calling party wishing to speak to another party will pick up the telephone's handset, thus operating a button switch or "switchhook", which puts the telephone into an active state or "off hook" by connecting the transmitter (microphone), receiver (speaker) and related audio components to the line. This circuitry has a low resistance (less than 300 Ohms) which causes DC current (48 volts, nominal) from the telephone exchange to flow through the line. The exchange detects this DC current, attaches a digit receiver circuit to the line, and sends a dial tone to indicate readiness. On a modern telephone, the calling party then presses the number buttons in a sequence corresponding to the telephone number of the called party. The buttons are connected to a tone generator that produces DTMF tones which are sent to the exchange. A rotary dial telephone employs pulse dialing, sending electrical pulses corresponding to the telephone number to the exchange. (Most exchanges are still equipped to handle pulse dialing.) Provided the called party's line is not already active or "busy", the exchange sends an intermittent ringing signal (generally over 100 volts AC) to alert the called party to an incoming call. If the called party's line is active, the exchange sends a busy signal to the calling party. However, if the called party's line is active but has call waiting installed, the exchange sends an intermittent audible tone to the called party to indicate an incoming call. When a landline phone is inactive or "on hook", its alerting device is connected across the line through a capacitor, which prevents DC current from flowing through the line. The circuitry at the telephone exchange detects the absence of DC current flow and thus that the phone is on hook with only the alerting device electrically connected to the line. When a party initiates a call to this line, the ringing signal transmitted by the telephone exchange activates the alerting device on the line. When the called party picks up the handset, the switchhook disconnects the alerting device and connects the audio circuitry to the line. The resulting low resistance now causes DC current to flow through this line, confirming that the called phone is now active. Both phones being active and connected through the exchange, the parties may now converse as long as both phones remain off hook. When a party "hangs up", placing the handset back on the cradle or hook, DC current ceases to flow in that line, signaling the exchange to disconnect the call. Calls to parties beyond the local exchange are carried over "trunk" lines which establish connections between exchanges. In modern telephone networks, fiber-optic cable and digital technology are often employed in such connections. Satellite technology may be used for communication over very long distances. In most telephones, the transmitter and receiver (microphone and speaker) are located in the handset, although in a speakerphone these components may be located in the base or in a separate enclosure. Powered by the line, the transmitter produces an electric current whose voltage varies in response to the sound waves arriving at its diaphragm. The resulting current is transmitted along the telephone line to the local exchange then on to the other phone (via the local exchange or a larger network), where it passes through the coil of the receiver. The varying voltage in the coil produces a corresponding movement of the receiver's diaphragm, reproducing the sound waves present at the transmitter. A Lineman's handset is a telephone designed for testing the telephone network, and may be attached directly to aerial lines and other infrastructure components. History. Credit for inventing the electric telephone remains in dispute. As with other great inventions such as radio, television, light bulb, and computer, there were several inventors who did pioneer experimental work on voice transmission over a wire and improved on each other's ideas. Innocenzo Manzetti, Antonio Meucci, Johann Philipp Reis, Elisha Gray, Alexander Graham Bell, and Thomas Edison, among others, have all been credited with pioneer work on the telephone. A Hungarian engineer, Tivadar Puskás invented the Telephone exchange in 1876. The early history of the telephone is a confusing morass of claim and counterclaim, which was not clarified by the huge mass of lawsuits which hoped to resolve the patent claims of individuals. The Bell and Edison patents, however, were forensically victorious and commercially decisive. Early commercial instruments. Early telephones were technically diverse. Some used a liquid transmitter, some had a metal diaphragm that induced current in an electromagnet wound around a permanent magnet, and some were "dynamic" -their diaphragm vibrated a coil of wire in the field of a permanent magnet or the coil vibrated the diaphragm. This dynamic kind survived in small numbers through the 20th century in military and maritime applications where its ability to create its own electrical power was crucial. Most, however, used the Edison Berliner carbon transmitter, which was much louder than the other kinds, even though it required an induction coil, actually acting as an impedance matching transformer to make it compatible to the impedance of the line. The Edison patents kept the Bell monopoly viable into the 20th century, by which time the network was more important than the instrument. Early telephones were locally powered, using either a dynamic transmitter or by the powering of a transmitter with a local battery. One of the jobs of outside plant personnel was to visit each telephone periodically to inspect the battery. During the 20th century, "common battery" operation came to dominate, powered by "talk battery" from the telephone exchange over the same wires that carried the voice signals. Early telephones used a single wire for the subscriber's line, with ground return used to complete the circuit (as used in telegraphs). The earliest dynamic telephones also had only one opening for sound, and the user alternately listened and spoke (rather, shouted) into the same hole. Sometimes the instruments were operated in pairs at each end, making conversation more convenient but were more expensive. At first, the benefits of an exchange were not exploited. Telephones instead were leased in pairs to the subscriber, who had to arrange telegraph contractors to construct a line between them, for example between his home and his shop. Users who wanted the ability to speak to several different locations would need to obtain and set up three or four pairs of telephones. Western Union, already using telegraph exchanges, quickly extended the principle to its telephones in New York City and San Francisco, and Bell was not slow in appreciating the potential. Signalling began in an appropriately primitive manner. The user alerted the other end, or the exchange operator, by whistling into the transmitter. Exchange operation soon resulted in telephones being equipped with a bell, first operated over a second wire, and later over the same wire, but with a condenser (capacitor) in series with the bell coil to allow the AC ringer signal through while still blocking DC (keeping the phone "on hook"). Telephones connected to the earliest Strowger automatic exchanges had seven wires, one for the knife switch, one for each telegraph key, one for the bell, one for the push button and two for speaking. Rural and other telephones that were not on a common battery exchange had a magneto or hand-cranked generator to produce a high voltage alternating signal to ring the bells of other telephones on the line and to alert the operator. In the 1890s a new smaller style of telephone was introduced, packaged in three parts. The transmitter stood on a stand, known as a "candlestick" for its shape. When not in use, the receiver hung on a hook with a switch in it, known as a "switchhook." Previous telephones required the user to operate a separate switch to connect either the voice or the bell. With the new kind, the user was less likely to leave the phone "off the hook". In phones connected to magneto exchanges, the bell, induction coil, battery and magneto were in a separate "bell box." In phones connected to common battery exchanges, the bell box was installed under a desk, or other out of the way place, since it did not need a battery or magneto. Cradle designs were also used at this time, having a handle with the receiver and transmitter attached, separate from the cradle base that housed the magneto crank and other parts. They were larger than the "candlestick" and more popular. Disadvantages of single wire operation such as crosstalk and hum from nearby AC power wires had already led to the use of twisted pairs and, for long distance telephones, four-wire circuits. Users at the beginning of the 20th century did not place long distance calls from their own telephones but made an appointment to use a special sound proofed long distance telephone booth furnished with the latest technology. What turned out to be the most popular and longest lasting physical style of telephone was introduced in the early 20th century, including Bell's Model 102. A carbon granule transmitter and electromagnetic receiver were united in a single molded plastic handle, which when not in use sat in a cradle in the base unit. The of the Model 102 shows the direct connection of the receiver to the line, while the transmitter was induction coupled, with energy supplied by a local battery. The coupling transformer, battery, and ringer were in a separate enclosure. The dial switch in the base interrupted the line current by repeatedly but very briefly disconnecting the line 1-10 times for each digit, and the hook switch (in the center of the circuit diagram) permanently disconnected the line and the transmitter battery while the handset was on the cradle. After the 1930s, the base also enclosed the bell and induction coil, obviating the old separate bell box. Power was supplied to each subscriber line by central office batteries instead of a local battery, which required periodic service. For the next half century, the network behind the telephone became progressively larger and much more efficient, but after the dial was added the instrument itself changed little until touch tone replaced the dial in the 1960s. Digital telephony. The Public Switched Telephone Network (PSTN) has gradually evolved towards digital telephony which has improved the capacity and quality of the network. End-to-end analog telephone networks were first modified in the early 1960s by upgrading transmission networks with T1 carrier systems. Later technologies such as SONET and fiber optic transmission methods further advanced digital transmission. Although analog carrier systems existed, digital transmission made it possible to significantly increase the number of channels multiplexed on a single transmission medium. While today the end instrument remains analog, the analog signals reaching the aggregation point (Serving Area Interface (SAI) or the central office (CO)) are typically converted to digital signals. Digital loop carriers (DLC) are often used, placing the digital network ever closer to the customer premises, relegating the analog local loop to legacy status. IP telephony. Internet Protocol (IP) telephony (also known as Voice over Internet Protocol, VoIP), is a disruptive technology that is rapidly gaining ground against traditional telephone network technologies. As of January 2005, up to 10% of telephone subscribers in Japan and South Korea have switched to this digital telephone service. A January 2005 Newsweek article suggested that Internet telephony may be "the next big thing." As of 2006 many VoIP companies offer service to consumers and businesses. IP telephony uses an Internet connection and hardware IP Phones or softphones installed on personal computers to transmit conversations encoded as data packets. In addition to replacing POTS (plain old telephone service), IP telephony services are also competing with mobile phone services by offering free or lower cost connections via WiFi hotspots. VoIP is also used on private networks which may or may not have a connection to the global telephone network. Usage. By the end of 2006, there were a total of nearly 4 billion mobile and fixed-line subscribers and over 1 billion Internet users worldwide. This included 1.27 billion fixed-line subscribers and 2.68 billion mobile subscribers. Telephone operating companies. In some countries, many telephone operating companies (commonly abbreviated to "telco" in American English) are in competition to provide telephone services. Some of them are included in the following list. However, the list only includes facilities based providers and not companies which lease services from facilities based providers in order to serve their customers. |