romikgosai/squad_modified huggingface dataset:
Machine vision systems often require bright and homogeneous illumination, so features of interest are easier to process. LEDs are often used for this purpose, and this is likely to remain one of their major uses until the price drops low enough to make signaling and illumination uses more widespread. Barcode scanners are the most common example of machine vision, and many low cost products use red LEDs instead of lasers. Optical computer mice are an example of LEDs in machine vision, as it is used to provide an even light source on the surface for the miniature camera within the mouse. LEDs constitute a nearly ideal light source for machine vision systems for several reasons:

Questions and answers:
['
Q: LEDs are often used for what type of systems?
A: Machine vision', '
Q: Why are LEDs preferred for machine vision systems?
A: so features of interest are easier to process', '
Q: What can help make LEDs more widely used?
A: price drops', '
Q: What is the most common example of a machine vision system?
A: Barcode scanners', '
Q: Where are some LEDs in machine vision systems found?
A: Optical computer mice']
The light from LEDs can be modulated very quickly so they are used extensively in optical fiber and free space optics communications. This includes remote controls, such as for TVs, VCRs, and LED Computers, where infrared LEDs are often used. Opto-isolators use an LED combined with a photodiode or phototransistor to provide a signal path with electrical isolation between two circuits. This is especially useful in medical equipment where the signals from a low-voltage sensor circuit (usually battery-powered) in contact with a living organism must be electrically isolated from any possible electrical failure in a recording or monitoring device operating at potentially dangerous voltages. An optoisolator also allows information to be transferred between circuits not sharing a common ground potential.

Questions and answers:
['
Q: Where are LEDs often used?
A: free space optics communications', '
Q: Where are opto-isolators found?
A: medical equipment', '
Q: What is an example of a device that uses free space optic communications?
A: remote controls', '
Q: What does an optoisolator do?
A: allows information to be transferred between circuits not sharing a common ground potential', '
Q: In what common household item can you find infrared LEDs?
A: LED Computers']
Many sensor systems rely on light as the signal source. LEDs are often ideal as a light source due to the requirements of the sensors. LEDs are used as motion sensors, for example in optical computer mice. The Nintendo Wii's sensor bar uses infrared LEDs. Pulse oximeters use them for measuring oxygen saturation. Some flatbed scanners use arrays of RGB LEDs rather than the typical cold-cathode fluorescent lamp as the light source. Having independent control of three illuminated colors allows the scanner to calibrate itself for more accurate color balance, and there is no need for warm-up. Further, its sensors only need be monochromatic, since at any one time the page being scanned is only lit by one color of light. Since LEDs can also be used as photodiodes, they can be used for both photo emission and detection. This could be used, for example, in a touchscreen that registers reflected light from a finger or stylus. Many materials and biological systems are sensitive to, or dependent on, light. Grow lights use LEDs to increase photosynthesis in plants, and bacteria and viruses can be removed from water and other substances using UV LEDs for sterilization.

Questions and answers:
['
Q: What video game console uses infrared LEDs?
A: Nintendo Wii', '
Q: What device uses infrared LEDs to measure oxygen saturation?
A: Pulse oximeters', '
Q: Some flatbed scanners use what type of LED?
A: RGB LEDs', '
Q: By using LEDs, scanners do not have to what?
A: warm-up', '
Q: Grow lights use LEDs for what process?
A: increase photosynthesis in plants']
LEDs have also been used as a medium-quality voltage reference in electronic circuits. The forward voltage drop (e.g. about 1.7 V for a normal red LED) can be used instead of a Zener diode in low-voltage regulators. Red LEDs have the flattest I/V curve above the knee. Nitride-based LEDs have a fairly steep I/V curve and are useless for this purpose. Although LED forward voltage is far more current-dependent than a Zener diode, Zener diodes with breakdown voltages below 3 V are not widely available.

Questions and answers:
['
Q: What quality has LEDs been used as?
A: medium-quality', '
Q: What LED has the flattest I/V curve above the knee?
A: Red', '
Q: What LEDs have a very steep I/V curve?
A: Nitride-based LEDs', '
Q: LED forward voltage is more current-dependent than what diode?
A: Zener', '
Q: Zener diodes below what voltage are not widely available?
A: 3 V']
Birds (Aves) are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. They rank as the class of tetrapods with the most living species, at approximately ten thousand, with more than half of these being passerines, sometimes known as perching birds or, less accurately, as songbirds.

Questions and answers:
['
Q: What is a group of endothermic vertebrates characterised by feathers and toothless beaked jaws?
A: Birds', '
Q: What is the smallest bird?
A: bee hummingbird', '
Q: What is the largest bird?
A: ostrich', '
Q: What is the size of the smallest bird?
A: 5 cm (2 in)', '
Q: What is the size of the largest bird?
A: 2.75 m (9 ft)']
The fossil record indicates that birds are the last surviving dinosaurs, having evolved from feathered ancestors within the theropod group of saurischian dinosaurs. True birds first appeared during the Cretaceous period, around 100 million years ago. DNA-based evidence finds that birds diversified dramatically around the time of the Cretaceous–Paleogene extinction event that killed off all other dinosaurs. Birds in South America survived this event and then migrated to other parts of the world via multiple land bridges while diversifying during periods of global cooling. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of fully powered flight, and many retained primitive characteristics like toothy jaws in place of beaks, and long bony tails.

Questions and answers:
['
Q: What are the last surviving dinosaurs, according o the fossil record?
A: birds', '
Q: When did true birds first appear?
A: Cretaceous period', '
Q: Name an example of an early stem-bird.
A: Archaeopteryx']
Birds have wings which are more or less developed depending on the species; the only known groups without wings are the extinct moas and elephant birds. Wings, which evolved from forelimbs, give most birds the ability to fly, although further speciation has led to some flightless birds, including ratites, penguins, and diverse endemic island species of birds. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly the aforementioned flightless penguins, and also members of the duck family, have also evolved for swimming. Birds, specifically Darwin's finches, played an important part in the inception of Darwin's theory of evolution by natural selection.

Questions and answers:
['
Q: What makes birds uniquely adapted for flight?
A: digestive and respiratory systems', "
Q: What type of bird particularly played an important part in the inception of Darwin's theory of evolution by natural selection?
A: Darwin's finches", '
Q: Which part of the bird developed from forelimbs?
A: Wings']
Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture. Many species annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have polygynous ("many females") or, rarely, polyandrous ("many males") breeding systems. Birds produce offspring by laying eggs which are fertilized through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilized, though unfertilized eggs do not produce offspring.

Questions and answers:
['
Q: Which type of birds are among the most intelligent animals?
A: corvids and parrots', '
Q: How to birds produce offspring?
A: by laying eggs which are fertilized through sexual reproduction', '
Q: Where are eggs usually laid?
A: nest']
Many species of birds are economically important. Domesticated and undomesticated birds (poultry and game) are important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertilizer. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry.

Questions and answers:
['
Q: Which birds are popular as pets?
A: Songbirds, parrots', '
Q: What is guano?
A: bird excrement', '
Q: What is the name of bird excrement?
A: Guano', '
Q: What is harvested for use as fertilizer?
A: Guano', '
Q: How many species of birds have become extinct as a result of human activity?
A: 120–130']
Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria. During the late 1990s, Aves was most commonly defined phylogenetically as all descendants of the most recent common ancestor of modern birds and Archaeopteryx lithographica. However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, and is used by many scientists including adherents of the Phylocode system. Gauthier defined Aves to include only the crown group of the set of modern birds. This was done by excluding most groups known only from fossils, and assigning them, instead, to the Avialae, in part to avoid the uncertainties about the placement of Archaeopteryx in relation to animals traditionally thought of as theropod dinosaurs.

Questions and answers:
['
Q: Besides Aves, what group contains the only living representatives of the reptile clade Archosauria?
A: clade Crocodilia', '
Q: Who defined Aves to include only the crown group of the set of modern birds?
A: Gauthier', '
Q: What is a sister group to Aves?
A: clade Crocodilia']
Based on fossil and biological evidence, most scientists accept that birds are a specialized subgroup of theropod dinosaurs, and more specifically, they are members of Maniraptora, a group of theropods which includes dromaeosaurs and oviraptorids, among others. As scientists have discovered more theropods closely related to birds, the previously clear distinction between non-birds and birds has become blurred. Recent discoveries in the Liaoning Province of northeast China, which demonstrate many small theropod feathered dinosaurs, contribute to this ambiguity.

Questions and answers:
['
Q: What evidence leads most scientists to accept that birds are a specialized subgroup of theropod dinosaurs?
A: fossil and biological evidence', '
Q: What is a group of theropods which include dromaeosaurs and oviraptorids?
A: Maniraptora', '
Q: Recent discoveries in what country demonstrate many small theropod feathered dinosaurs.
A: China']
The consensus view in contemporary paleontology is that the flying theropods, or avialans, are the closest relatives of the deinonychosaurs, which include dromaeosaurids and troodontids. Together, these form a group called Paraves. Some basal members of this group, such as Microraptor, have features which may have enabled them to glide or fly. The most basal deinonychosaurs were very small. This evidence raises the possibility that the ancestor of all paravians may have been arboreal, have been able to glide, or both. Unlike Archaeopteryx and the non-avialan feathered dinosaurs, who primarily ate meat, recent studies suggest that the first avialans were omnivores.

Questions and answers:
['
Q: What are the closest relatives of the deinonychosaurs?
A: flying theropods', '
Q: What are the closest relatives of flying theropods?
A: deinonychosaurs', '
Q: Dromaeosaurids and troodontids are members of what group?
A: deinonychosaurs']
The Late Jurassic Archaeopteryx is well known as one of the first transitional fossils to be found, and it provided support for the theory of evolution in the late 19th century. Archaeopteryx was the first fossil to display both clearly traditional reptilian characteristics: teeth, clawed fingers, and a long, lizard-like tail, as well as wings with flight feathers similar to those of modern birds. It is not considered a direct ancestor of birds, though it is possibly closely related to the true ancestor.

Questions and answers:
['
Q: What is known as one of the first transitional fossils to be found?
A: Late Jurassic Archaeopteryx', '
Q: What was the first fossil to display both clearly traditional reptilian characteristics?
A: Archaeopteryx', '
Q: Fossils with teeth, clawed fingers and a long lizard-like tail have what type of characteristics?
A: reptilian']
The earliest known avialan fossils come from the Tiaojishan Formation of China, which has been dated to the late Jurassic period (Oxfordian stage), about 160 million years ago. The avialan species from this time period include Anchiornis huxleyi, Xiaotingia zhengi, and Aurornis xui. The well-known early avialan, Archaeopteryx, dates from slightly later Jurassic rocks (about 155 million years old) from Germany. Many of these early avialans shared unusual anatomical features that may be ancestral to modern birds, but were later lost during bird evolution. These features include enlarged claws on the second toe which may have been held clear of the ground in life, and long feathers or "hind wings" covering the hind limbs and feet, which may have been used in aerial maneuvering.

Questions and answers:
['
Q: The Oxfordian stage is also known as what?
A: late Jurassic period', '
Q: How long ago was the late Jurassic period?
A: about 160 million years ago', '
Q: What may have been used in aerial maneuvering?
A: hind wings', '
Q: Avian species such as Anchiornis huxleyi and Xiaotingia zhengi are from which time period?
A: late Jurassic period']
Avialans diversified into a wide variety of forms during the Cretaceous Period. Many groups retained primitive characteristics, such as clawed wings and teeth, though the latter were lost independently in a number of avialan groups, including modern birds (Aves). While the earliest forms, such as Archaeopteryx and Jeholornis, retained the long bony tails of their ancestors, the tails of more advanced avialans were shortened with the advent of the pygostyle bone in the group Pygostylia. In the late Cretaceous, around 95 million years ago, the ancestor of all modern birds also evolved a better sense of smell.

Questions and answers:
['
Q: During which time period did avialans diversify into a wide variety of forms?
A: Cretaceous Period', '
Q: Which forms retained the long bony tails of their ancestors?
A: Archaeopteryx and Jeholornis', '
Q: When did the ancestor of all modern birds evolve a better sense of smell?
A: late Cretaceous', '
Q: How long ago was the late Cretaceous period?
A: around 95 million years ago']
The first large, diverse lineage of short-tailed avialans to evolve were the enantiornithes, or "opposite birds", so named because the construction of their shoulder bones was in reverse to that of modern birds. Enantiornithes occupied a wide array of ecological niches, from sand-probing shorebirds and fish-eaters to tree-dwelling forms and seed-eaters. While they were the dominant group of avialans during the Cretaceous period, enantiornithes became extinct along with many other dinosaur groups at the end of the Mesozoic era.

Questions and answers:
['
Q: What were the first large, diverse lineage of short-tailed avialans to evolve?
A: enantiornithes', '
Q: Because of the construction of their shoulder bones, what were the enantiornithes called?
A: opposite birds', '
Q: What was the dominant group of avialans during the Cretaceous period?
A: enantiornithes', '
Q: When did enantiornithes become extinct?
A: end of the Mesozoic era']
Many species of the second major avialan lineage to diversify, the Euornithes (meaning "true birds", because they include the ancestors of modern birds), were semi-aquatic and specialized in eating fish and other small aquatic organisms. Unlike the enantiornithes, which dominated land-based and arboreal habitats, most early euornithes lacked perching adaptations and seem to have included shorebird-like species, waders, and swimming and diving species. The later included the superficially gull-like Ichthyornis, the Hesperornithiformes, which became so well adapted to hunting fish in marine environments that they lost the ability to fly and became primarily aquatic. The early euornithes also saw the development of many traits associated with modern birds, like strongly keeled breastbones, toothless, beaked portions of their jaws (though most non-avian euornithes retained teeth in other parts of the jaws). Euornithes also included the first avialans to develop true pygostyle and a fully mobile fan of tail feathers, which may have replaced the "hind wing" as the primary mode of aerial maneuverability and braking in flight.

Questions and answers:
['
Q: What group became the first avialans to develop true pygostyle and a fully mobile fan of tail feathers?
A: Euornithes', '
Q: What does Euornithes mean?
A: true birds', '
Q: Why does Euornithes mean "true birds?"
A: because they include the ancestors of modern birds', '
Q: What may have replaced the "hind wing" as the primary mode of aerial maneuverability?
A: fully mobile fan of tail feathers']
All modern birds lie within the crown group Aves (alternately Neornithes), which has two subdivisions: the Palaeognathae, which includes the flightless ratites (such as the ostriches) and the weak-flying tinamous, and the extremely diverse Neognathae, containing all other birds. These two subdivisions are often given the rank of superorder, although Livezey and Zusi assigned them "cohort" rank. Depending on the taxonomic viewpoint, the number of known living bird species varies anywhere from 9,800 to 10,050.

Questions and answers:
['
Q: All modern birds lie within which crown group?
A: Aves', '
Q: What is another name for Aves?
A: Neornithes', '
Q: The two subdivisions of what group include Palaeognathae and Neognathae?
A: Aves', '
Q: What is the number range of living bird species?
A: 9,800 to 10,050']
The earliest divergence within the Neognathes was that of the Galloanserae, the superorder containing the Anseriformes (ducks, geese, swans and screamers) and the Galliformes (the pheasants, grouse, and their allies, together with the mound builders and the guans and their allies). The earliest fossil remains of true birds come from the possible galliform Austinornis lentus, dated to about 85 million years ago, but the dates for the actual splits are much debated by scientists. The Aves are agreed to have evolved in the Cretaceous, and the split between the Galloanseri from other Neognathes occurred before the Cretaceous–Paleogene extinction event, but there are different opinions about whether the radiation of the remaining Neognathes occurred before or after the extinction of the other dinosaurs. This disagreement is in part caused by a divergence in the evidence; molecular dating suggests a Cretaceous radiation, while fossil evidence supports a Cenozoic radiation. Attempts to reconcile the molecular and fossil evidence have proved controversial, but recent results show that all the extant groups of birds originated from only a small handful of species that survived the Cretaceous–Paleogene extinction.

Questions and answers:
['
Q: What was the earliest divergence within the Neognathes?
A: Galloanserae', '
Q: What is the superorder containing the Anseriformes?
A: Galloanserae', '
Q: Ducks, geese, swans and screamers are part of which group?
A: Anseriformes', '
Q: The pheasants, grouse and their allies form which group?
A: Galliformes']
The classification of birds is a contentious issue. Sibley and Ahlquist's Phylogeny and Classification of Birds (1990) is a landmark work on the classification of birds, although it is frequently debated and constantly revised. Most evidence seems to suggest the assignment of orders is accurate, but scientists disagree about the relationships between the orders themselves; evidence from modern bird anatomy, fossils and DNA have all been brought to bear on the problem, but no strong consensus has emerged. More recently, new fossil and molecular evidence is providing an increasingly clear picture of the evolution of modern bird orders. The most recent effort is drawn above and is based on whole genome sequencing of 48 representative species.

Questions and answers:
["
Q: Sibley and Ahlquist' Phylogeny and Classification of Birds is a landmark work on the classification of what animals?
A: birds", '
Q: What do scientists disagree about?
A: relationships between the orders themselves', '
Q: What do scientists tend to agree on?
A: the assignment of orders is accurate']
Birds live and breed in most terrestrial habitats and on all seven continents, reaching their southern extreme in the snow petrel's breeding colonies up to 440 kilometres (270 mi) inland in Antarctica. The highest bird diversity occurs in tropical regions. It was earlier thought that this high diversity was the result of higher speciation rates in the tropics, however recent studies found higher speciation rates in the high latitudes that were offset by greater extinction rates than in the tropics. Several families of birds have adapted to life both on the world's oceans and in them, with some seabird species coming ashore only to breed and some penguins have been recorded diving up to 300 metres (980 ft).

Questions and answers:
['
Q: Birds live on how many continents?
A: seven', '
Q: Highest bird diversity occurs in which regions?
A: tropical', '
Q: Some penguins have been recording diving up to how many feet?
A: 980', '
Q: Some seabird species only come ashore for what purpose?
A: to breed']
Many bird species have established breeding populations in areas to which they have been introduced by humans. Some of these introductions have been deliberate; the ring-necked pheasant, for example, has been introduced around the world as a game bird. Others have been accidental, such as the establishment of wild monk parakeets in several North American cities after their escape from captivity. Some species, including cattle egret, yellow-headed caracara and galah, have spread naturally far beyond their original ranges as agricultural practices created suitable new habitat.

Questions and answers:
['
Q: The ring-necked pheasant has been introduced as what kind of bird?
A: game bird', '
Q: Why have some species spread naturally far beyond their original ranges?
A: agricultural practices created suitable new habitat', '
Q: Where have many birds established breeding populations?
A: in areas to which they have been introduced by humans']