There are several types of multi-color white LEDs: di-, tri-, and tetrachromatic white LEDs. Several key factors that play among these different methods, include color stability, color rendering capability, and luminous efficacy. Often, higher efficiency will mean lower color rendering, presenting a trade-off between the luminous efficacy and color rendering. For example, the dichromatic white LEDs have the best luminous efficacy (120 lm/W), but the lowest color rendering capability. However, although tetrachromatic white LEDs have excellent color rendering capability, they often have poor luminous efficacy. Trichromatic white LEDs are in between, having both good luminous efficacy (>70 lm/W) and fair color rendering capability.

What is one type of multi-color white LED?

tetrachromatic

What is a factor that may be different in the various types of multi-color white LEDs?

luminous efficacy

Higher efficiency in multi-color white LEDs may mean what?

lower color rendering

What type has the best luminous efficacy?

dichromatic white LEDs

What luminous efficacy does trichromatic white LEDs have?

>70 lm/W

What is one type of solo-color white LED?

I'm not sure.

What is a factor that may be different in the various types of multi-color red LEDs?

I'm not sure.

Higher efficiency in multi-color white LEDs don't mean what?

I'm not sure.

What type has the worst luminous efficacy?

I'm not sure.

What luminous efficacy does non-trichromatic white LEDs have?

I'm not sure.


Multi-color LEDs offer not merely another means to form white light but a new means to form light of different colors. Most perceivable colors can be formed by mixing different amounts of three primary colors. This allows precise dynamic color control. As more effort is devoted to investigating this method, multi-color LEDs should have profound influence on the fundamental method that we use to produce and control light color. However, before this type of LED can play a role on the market, several technical problems must be solved. These include that this type of LED's emission power decays exponentially with rising temperature, resulting in a substantial change in color stability. Such problems inhibit and may preclude industrial use. Thus, many new package designs aimed at solving this problem have been proposed and their results are now being reproduced by researchers and scientists.

Multi-color LEDs offer what else besides the formation of white light?

to form light of different colors

What problem must be solved before multi-color LEDs can play a role in the market?

power decays exponentially with rising temperature

What problem results when rising temperatures decays power?

substantial change in color stability

Multi-color LEDs offer what else besides the formation of red light?

I'm not sure.

What problem must be solved before non-multi-color LEDs can play a role in the market?

I'm not sure.

What problem results when lowering temperatures decays power?

I'm not sure.


This method involves coating LEDs of one color (mostly blue LEDs made of InGaN) with phosphors of different colors to form white light; the resultant LEDs are called phosphor-based or phosphor-converted white LEDs (pcLEDs). A fraction of the blue light undergoes the Stokes shift being transformed from shorter wavelengths to longer. Depending on the color of the original LED, phosphors of different colors can be employed. If several phosphor layers of distinct colors are applied, the emitted spectrum is broadened, effectively raising the color rendering index (CRI) value of a given LED.

What method involves coating LEDs of one color with phosphors of different colors?

phosphor-converted white LEDs (pcLEDs)

In pcLEDs method, a fraction of what light is used?

blue

What shift does blue light undergo in the pcLEDs method?

Stokes

The different colors of phosphors that can be used is based on what?

the color of the original LED

What broadens the emitted spectrum in a pcLEDs method?

If several phosphor layers of distinct colors are applied

What method involves coating LEDs of multiple color with phosphors of different colors?

I'm not sure.

In pcLEDs method, a fraction of what light is never used?

I'm not sure.

What shift does non-blue light undergo in the pcLEDs method?

I'm not sure.

he different colors of phosphors that can't be used is based on what?

I'm not sure.


Phosphor-based LED efficiency losses are due to the heat loss from the Stokes shift and also other phosphor-related degradation issues. Their luminous efficacies compared to normal LEDs depend on the spectral distribution of the resultant light output and the original wavelength of the LED itself. For example, the luminous efficacy of a typical YAG yellow phosphor based white LED ranges from 3 to 5 times the luminous efficacy of the original blue LED because of the human eye's greater sensitivity to yellow than to blue (as modeled in the luminosity function). Due to the simplicity of manufacturing the phosphor method is still the most popular method for making high-intensity white LEDs. The design and production of a light source or light fixture using a monochrome emitter with phosphor conversion is simpler and cheaper than a complex RGB system, and the majority of high-intensity white LEDs presently on the market are manufactured using phosphor light conversion.

Why is efficiency sometimes lost in phosphor-based LEDs?

heat loss from the Stokes shift

What do phosphor-based LEDs luminous efficacies depend on?

the spectral distribution of the resultant light output

What are some of the luminous efficacies of yellow phosphor based white LED compared to blue?

3 to 5 times the luminous efficacy

What is the most popular method for making high-intensity white LEDs?

phosphor method

What type of emitter is used in phosphor-based white LED methods?

monochrome

Why is efficiency never lost in phosphor-based LEDs?

I'm not sure.

What don't phosphor-based LEDs luminous efficacies depend on?

I'm not sure.

What are some of the luminous efficacies of yellow phosphor based red LED compared to blue?

I'm not sure.

What type of emitter is used in non-phosphor-based white LED methods?

I'm not sure.


Among the challenges being faced to improve the efficiency of LED-based white light sources is the development of more efficient phosphors. As of 2010, the most efficient yellow phosphor is still the YAG phosphor, with less than 10% Stoke shift loss. Losses attributable to internal optical losses due to re-absorption in the LED chip and in the LED packaging itself account typically for another 10% to 30% of efficiency loss. Currently, in the area of phosphor LED development, much effort is being spent on optimizing these devices to higher light output and higher operation temperatures. For instance, the efficiency can be raised by adapting better package design or by using a more suitable type of phosphor. Conformal coating process is frequently used to address the issue of varying phosphor thickness.

What can improve the efficiency of LED-based white light?

more efficient phosphors

What is the most efficient yellow phosphor?

YAG phosphor

What is the percentage of stoke shift loss in YAG phosphor?

less than 10%

What area are scientists looking into regarding phosphor LED development?

higher operation temperatures

What is one method that can raise the efficiency of phosphor-based LEDs?

adapting better package design

What can improve the efficiency of non-LED-based white light?

I'm not sure.

What is the least efficient yellow phosphor?

I'm not sure.

What is the percentage of stoke shift loss in non-YAG phosphor?

I'm not sure.

What area are scientists looking into regarding phosphor non-LED development?

I'm not sure.

What is one method that can lower the efficiency of phosphor-based LEDs?

I'm not sure.


White LEDs can also be made by coating near-ultraviolet (NUV) LEDs with a mixture of high-efficiency europium-based phosphors that emit red and blue, plus copper and aluminium-doped zinc sulfide (ZnS:Cu, Al) that emits green. This is a method analogous to the way fluorescent lamps work. This method is less efficient than blue LEDs with YAG:Ce phosphor, as the Stokes shift is larger, so more energy is converted to heat, but yields light with better spectral characteristics, which render color better. Due to the higher radiative output of the ultraviolet LEDs than of the blue ones, both methods offer comparable brightness. A concern is that UV light may leak from a malfunctioning light source and cause harm to human eyes or skin.

White LEDs can be made by coating what?

near-ultraviolet (NUV) LEDs

What are near-ultraviolet LEDs coated with to create white LED?

copper and aluminium-doped zinc sulfide (ZnS:Cu, Al)

What device also works in a similar way as NUV LEDs?

fluorescent lamps

The method of coating NUVs less efficient than what other LEDs?

blue

What light can harm human eyes or skin?

UV light

White LEDs can be made by not coating what?

I'm not sure.

What are non-near-ultraviolet LEDs coated with to create white LED?

I'm not sure.

What device also works in a similar way as non-NUV LEDs?

I'm not sure.

The method of coating NUVs more efficient than what other LEDs?

I'm not sure.


A new style of wafers composed of gallium-nitride-on-silicon (GaN-on-Si) is being used to produce white LEDs using 200-mm silicon wafers. This avoids the typical costly sapphire substrate in relatively small 100- or 150-mm wafer sizes. The sapphire apparatus must be coupled with a mirror-like collector to reflect light that would otherwise be wasted. It is predicted that by 2020, 40% of all GaN LEDs will be made with GaN-on-Si. Manufacturing large sapphire material is difficult, while large silicon material is cheaper and more abundant. LED companies shifting from using sapphire to silicon should be a minimal investment.

What is being used to produce white LEDs?

wafers composed of gallium-nitride-on-silicon

What size are the wafers used to create white LEDs?

By using silicon wafers, what is being avoided?

costly sapphire substrate

What needs to be used to reflect light that would otherwise be wasted?

mirror-like collector

By what year will% of all GaN LEDs be made with gallium-nitride-on-silicon wafers?

What is being used to produce white non-LEDs?

I'm not sure.

What size are the wafers used to create red LEDs?

I'm not sure.

By using silicon wafers, what is not being avoided?

I'm not sure.

What needs to not be used to reflect light that would otherwise be wasted?

I'm not sure.


Quantum dots (QD) are semiconductor nanocrystals that possess unique optical properties. Their emission color can be tuned from the visible throughout the infrared spectrum. This allows quantum dot LEDs to create almost any color on the CIE diagram. This provides more color options and better color rendering than white LEDs since the emission spectrum is much narrower, characteristic of quantum confined states. There are two types of schemes for QD excitation. One uses photo excitation with a primary light source LED (typically blue or UV LEDs are used). The other is direct electrical excitation first demonstrated by Alivisatos et al.

What nanocrystals possess unique optical properties?

Quantum dots

Quantum Dot LEDs can do what special skill?

create almost any color on the CIE diagram

The narrowing of the emission spectrum in Quantum Dot LEDs allows them to do what?

better color rendering

How many types of schemes are there in Quantum Dot LED excitation?

two

What non-nanocrystals possess unique optical properties?

I'm not sure.

Quantum Dot LEDs don't do what special skill?

I'm not sure.

The narrowing of the emission spectrum in Quantum Dot LEDs disallows them to do what?

I'm not sure.

How many types of schemes are there in non-Quantum Dot LED excitation?

I'm not sure.


The structure of QD-LEDs used for the electrical-excitation scheme is similar to basic design of OLEDs. A layer of quantum dots is sandwiched between layers of electron-transporting and hole-transporting materials. An applied electric field causes electrons and holes to move into the quantum dot layer and recombine forming an exciton that excites a QD. This scheme is commonly studied for quantum dot display. The tunability of emission wavelengths and narrow bandwidth is also beneficial as excitation sources for fluorescence imaging. Fluorescence near-field scanning optical microscopy (NSOM) utilizing an integrated QD-LED has been demonstrated.

What is one scheme of Quantum Dot excitation?

electrical-excitation

What is one material used in electrical-excitation?

hole-transporting materials

During the electrical-excitation scheme, what moves into the quantum dot layer?

electrons and holes

A Quantum Dot LED has been used in what?

near-field scanning optical microscopy (NSOM)

What is one scheme of non-Quantum Dot excitation?

I'm not sure.

What is one material used in non-electrical-excitation?

I'm not sure.

During the electrical-excitation scheme, what moves into the non-quantum dot layer?

I'm not sure.

A Quantum Dot non-LED has been used in what?

I'm not sure.


High-power LEDs (HP-LEDs) or high-output LEDs (HO-LEDs) can be driven at currents from hundreds of mA to more than an ampere, compared with the tens of mA for other LEDs. Some can emit over a thousand lumens. LED power densities up to 300 W/cm2 have been achieved. Since overheating is destructive, the HP-LEDs must be mounted on a heat sink to allow for heat dissipation. If the heat from a HP-LED is not removed, the device will fail in seconds. One HP-LED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp.

How many lumens can some high-power LEDs emit?

over a thousand

Up to how many densities have been achieved with LED power?

300 W/cm2

Why must High-power LEDs be mounted on a heat sink?

to allow for heat dissipation

What will happen if the heat from a high-power LED is not removed?

the device will fail in seconds

What can one high-power LED replace?

incandescent bulb in a flashlight

How many lumens can some low-power LEDs emit?

I'm not sure.

Up to how many densities have never been achieved with LED power?

I'm not sure.

Why must High-power LEDs be mounted on a heat rise?

I'm not sure.

What will happen if the heat from a low-power LED is not removed?

I'm not sure.

What can one low-power LED replace?

I'm not sure.


LEDs have been developed by Seoul Semiconductor that can operate on AC power without the need for a DC converter. For each half-cycle, part of the LED emits light and part is dark, and this is reversed during the next half-cycle. The efficacy of this type of HP-LED is typically 40 lm/W. A large number of LED elements in series may be able to operate directly from line voltage. In 2009, Seoul Semiconductor released a high DC voltage LED, named as 'Acrich MJT', capable of being driven from AC power with a simple controlling circuit. The low-power dissipation of these LEDs affords them more flexibility than the original AC LED design.

What company has developed LEDs that can operate on AC power?

Seoul Semiconductor

What is the efficacy of an AC powered HP-LED?

40 lm/W

When did Seoul Semiconductor release the first high DC voltage LED?

What is so good about ac powered HP-LEDs?

more flexibility

What did Seoul Semiconductor name their ac powered HP-LED?

Acrich MJT

What company has developed non-LEDs that can operate on AC power?

I'm not sure.

What is the efficacy of an non-AC powered HP-LED?

I'm not sure.

When did non-Seoul Semiconductor release the first high DC voltage LED?

I'm not sure.

What is so good about ac powered non-HP-LEDs?

I'm not sure.


Alphanumeric LEDs are available in seven-segment, starburst and dot-matrix format. Seven-segment displays handle all numbers and a limited set of letters. Starburst displays can display all letters. Dot-matrix displays typically use 5x7 pixels per character. Seven-segment LED displays were in widespread use in the 1970s and 1980s, but rising use of liquid crystal displays, with their lower power needs and greater display flexibility, has reduced the popularity of numeric and alphanumeric LED displays.

What type of LEDs are available in seven-segment format?

Alphanumeric

What is another format that Alphanumeric LEDs are available in?

dot-matrix

Which alphanumeric LED display can display all letters?

Starburst

What type of pixels does a dot matrix display use?

What has reduced the popularity of numeric LED displays?

liquid crystal displays

What type of LEDs are available in eight-segment format?

I'm not sure.

What is another format that non-Alphanumeric LEDs are available in?

I'm not sure.

Which non-alphanumeric LED display can display all letters?

I'm not sure.

What type of pixels does a dot matrix display not use?

I'm not sure.

What has reduced the popularity of numeric non-LED displays?

I'm not sure.


Digital-RGB LEDs are RGB LEDs that contain their own "smart" control electronics. In addition to power and ground, these provide connections for data-in, data-out, and sometimes a clock or strobe signal. These are connected in a daisy chain, with the data in of the first LED sourced by a microprocessor, which can control the brightness and color of each LED independently of the others. They are used where a combination of maximum control and minimum visible electronics are needed such as strings for Christmas and LED matrices. Some even have refresh rates in the kHz range, allowing for basic video applications.

What makes RGB LEDs different?

contain their own "smart" control electronics

How are Digital-RGB LED strobe signals connected?

in a daisy chain

What object sources the data in of the first LED of a digital rgb LED?

microprocessor

The microprocessor does what in a digital RGB LED?

control the brightness and color of each LED independently of the others

What is one example of where Digital RGB LED lights are used?

Christmas

What makes RGB LEDs the same?

I'm not sure.

How are non-Digital-RGB LED strobe signals connected?

I'm not sure.

What object sources the data in of the first non-LED of a digital rgb LED?

I'm not sure.

The non-microprocessor does what in a digital RGB LED?

I'm not sure.

What is one example of where non-Digital RGB LED lights are used?

I'm not sure.


An LED filament consists of multiple LED dice connected in series on a common longitudinal substrate that form a thin rod reminiscent of a traditional incandescent filament. These are being used as a low cost decorative alternative for traditional light bulbs that are being phased out in many countries. The filaments require a rather high voltage to light to nominal brightness, allowing them to work efficiently and simply with mains voltages. Often a simple rectifier and capacitive current limiting are employed to create a low-cost replacement for a traditional light bulb without the complexity of creating a low voltage, high current converter which is required by single die LEDs. Usually they are packaged in a sealed enclosure with a shape similar to lamps they were designed to replace (e.g. a bulb), and filled with inert nitrogen or carbon dioxide gas to remove heat efficiently.

What does an LED filament consist of?

multiple LED dice

How are LED filaments used?

a low cost decorative alternative for traditional light bulbs

What type of voltage is needed for LED filaments?

high

What helps LED filaments remain low cost?

a simple rectifier

Single die LEDs require what?

high current converter

What does an non-LED filament consist of?

I'm not sure.

How are non-LED filaments used?

I'm not sure.

What type of voltage is needed for non-LED filaments?

I'm not sure.

What helps non-LED filaments remain low cost?

I'm not sure.


The current–voltage characteristic of an LED is similar to other diodes, in that the current is dependent exponentially on the voltage (see Shockley diode equation). This means that a small change in voltage can cause a large change in current. If the applied voltage exceeds the LED's forward voltage drop by a small amount, the current rating may be exceeded by a large amount, potentially damaging or destroying the LED. The typical solution is to use constant-current power supplies to keep the current below the LED's maximum current rating. Since most common power sources (batteries, mains) are constant-voltage sources, most LED fixtures must include a power converter, at least a current-limiting resistor. However, the high resistance of three-volt coin cells combined with the high differential resistance of nitride-based LEDs makes it possible to power such an LED from such a coin cell without an external resistor.

How are LEDs similar to other diodes?

the current is dependent exponentially on the voltage

What can cause a large change in current in LEDs?

a small change in voltage

What is a solution to preventing an LED failure?

use constant-current power supplies

What feature do most LED fixtures need to have?

a power converter

What is a constant-voltage source?

batteries

How are non-LEDs similar to other diodes?

I'm not sure.

What can cause a large change in current in non-LEDs?

I'm not sure.

What is a solution to preventing an non-LED failure?

I'm not sure.

What feature do no LED fixtures need to have?

I'm not sure.


The vast majority of devices containing LEDs are "safe under all conditions of normal use", and so are classified as "Class 1 LED product"/"LED Klasse 1". At present, only a few LEDs—extremely bright LEDs that also have a tightly focused viewing angle of 8° or less—could, in theory, cause temporary blindness, and so are classified as "Class 2". The opinion of the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) of 2010, on the health issues concerning LEDs, suggested banning public use of lamps which were in the moderate Risk Group 2, especially those with a high blue component in places frequented by children. In general, laser safety regulations—and the "Class 1", "Class 2", etc. system—also apply to LEDs.

How are most LEDs classified?

Class 1 LED product

What does being a Class 1 LED product mean?

safe under all conditions of normal use

What type of LED can possibly cause blindness?

extremely bright LEDs

What class are extremely bright LEDs listed as?

Class 2

Which government advocated the banning of Class 2 LEDs?

French

How are most non-LEDs classified?

I'm not sure.

What does being a Class 2 LED product mean?

I'm not sure.

What type of LED can't cause blindness?

I'm not sure.

What class are extremely dark LEDs listed as?

I'm not sure.

Which government advocated the suppoert of Class 2 LEDs?

I'm not sure.


While LEDs have the advantage over fluorescent lamps that they do not contain mercury, they may contain other hazardous metals such as lead and arsenic. Regarding the toxicity of LEDs when treated as waste, a study published in 2011 stated: "According to federal standards, LEDs are not hazardous except for low-intensity red LEDs, which leached Pb [lead] at levels exceeding regulatory limits (186 mg/L; regulatory limit: 5). However, according to California regulations, excessive levels of copper (up to 3892 mg/kg; limit: 2500), lead (up to 8103 mg/kg; limit: 1000), nickel (up to 4797 mg/kg; limit: 2000), or silver (up to 721 mg/kg; limit: 500) render all except low-intensity yellow LEDs hazardous."

What substance does fluorescent lamps contain?

mercury

What dangerous metal can LEDs contain?

arsenic

Which LEDs are considered dangerous by a 2011 study?

low-intensity red

According to a California study, what harmful metal is in most LEDs?

lead

What LEDs are considered safer than any other?

low-intensity yellow LEDs

What substance does non-fluorescent lamps contain?

I'm not sure.

What dangerous metal can non-LEDs contain?

I'm not sure.

According to a California study, what harmful metal is in most non-LEDs?

I'm not sure.

What LEDs are considered riskier than any other?

I'm not sure.


One-color light is well suited for traffic lights and signals, exit signs, emergency vehicle lighting, ships' navigation lights or lanterns (chromacity and luminance standards being set under the Convention on the International Regulations for Preventing Collisions at Sea 1972, Annex I and the CIE) and LED-based Christmas lights. In cold climates, LED traffic lights may remain snow-covered. Red or yellow LEDs are used in indicator and alphanumeric displays in environments where night vision must be retained: aircraft cockpits, submarine and ship bridges, astronomy observatories, and in the field, e.g. night time animal watching and military field use.

What type of light is ideal for traffic signals?

One-color light

In what year were luminescence standards set?

What color LEDs are used when night vision is important?

Red or yellow

What is an example of a night vision needed area?

astronomy observatories

What is another use for one-color light?

exit signs

What type of light is not ideal for traffic signals?

I'm not sure.

In what year were non-luminescence standards set?

I'm not sure.

What color non-LEDs are used when night vision is important?

I'm not sure.

What is an example of a non-night vision needed area?

I'm not sure.


Because of their long life, fast switching times, and their ability to be seen in broad daylight due to their high output and focus, LEDs have been used in brake lights for cars' high-mounted brake lights, trucks, and buses, and in turn signals for some time, but many vehicles now use LEDs for their rear light clusters. The use in brakes improves safety, due to a great reduction in the time needed to light fully, or faster rise time, up to 0.5 second faster[citation needed] than an incandescent bulb. This gives drivers behind more time to react. In a dual intensity circuit (rear markers and brakes) if the LEDs are not pulsed at a fast enough frequency, they can create a phantom array, where ghost images of the LED will appear if the eyes quickly scan across the array. White LED headlamps are starting to be used. Using LEDs has styling advantages because LEDs can form much thinner lights than incandescent lamps with parabolic reflectors.

Why are LED lights sought after for various applications?

their long life

Because of their high output, LED lights are very useful where?

brake lights for cars

LED brake lights are how many times faster than incandescent ones?

0.5 second

What color LEDs are now starting to be used more?

White

What types of light can LEDs form better than incandescent?

thinner

Why are non-LED lights sought after for various applications?

I'm not sure.

Because of their low output, LED lights are very useful where?

I'm not sure.

ED brake lights are how many times slower than incandescent ones?

I'm not sure.

What color LEDs are now not used more?

I'm not sure.


Assistive listening devices in many theaters and similar spaces use arrays of infrared LEDs to send sound to listeners' receivers. Light-emitting diodes (as well as semiconductor lasers) are used to send data over many types of fiber optic cable, from digital audio over TOSLINK cables to the very high bandwidth fiber links that form the Internet backbone. For some time, computers were commonly equipped with IrDA interfaces, which allowed them to send and receive data to nearby machines via infrared.

Where are infrared LEDs used in everday life?

theaters

How are LEDs used in theaters?

to send sound to listeners' receivers

LEDs can send data over what type of cable?

fiber optic

What type of fiber forms the backbone of the internet?

very high bandwidth

Where are infrared non-LEDs used in everyday life?

I'm not sure.

How are non-LEDs used in theaters?

I'm not sure.

LEDs can't send data over what type of cable?

I'm not sure.

What type of fiber doesn't form the backbone of the internet?

I'm not sure.


In the US, one kilowatt-hour (3.6 MJ) of electricity currently causes an average 1.34 pounds (610 g) of CO
2 emission. Assuming the average light bulb is on for 10 hours a day, a 40-watt bulb will cause 196 pounds (89 kg) of CO
2 emission per year. The 6-watt LED equivalent will only cause 30 pounds (14 kg) of CO
2 over the same time span. A building’s carbon footprint from lighting can therefore be reduced by 85% by exchanging all incandescent bulbs for new LEDs if a building previously used only incandescent bulbs.

In what country does one kilowatt-hour of electricity causes 1.34 pounds of CO 2 emission?

US

How much CO2 emission would a 40-watt light bulb produce after 10 hours?

196 pounds

A 6-watt LED left on for 10 hours a day will emit how much CO 2?

30 pounds

How much can a building's carbon footprint be reduced by switching to LEDs?

In what country does one kilowatt-hour of electricity causes 1.34 pounds of CO 3 emission?

I'm not sure.

How much CO2 emission would a 50-watt light bulb produce after 10 hours?

I'm not sure.

A 9-watt LED left on for 10 hours a day will emit how much CO 2?

I'm not sure.

How much can a building's carbon footprint be reduced by switching to non-LEDs?

I'm not sure.


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:

LEDs are often used for what type of systems?

Machine vision

Why are LEDs preferred for machine vision systems?

so features of interest are easier to process

What can help make LEDs more widely used?

price drops

What is the most common example of a machine vision system?

Barcode scanners

Where are some LEDs in machine vision systems found?

Optical computer mice

non-LEDs are often used for what type of systems?

I'm not sure.

Why aren't LEDs preferred for machine vision systems?

I'm not sure.

What can't help make LEDs more widely used?

I'm not sure.

What is the most uncommon example of a machine vision system?

I'm not sure.

Where are some LEDs in machine vision systems not found?

I'm not sure.


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.

Where are LEDs often used?

free space optics communications

What is an example of a device that uses free space optic communications?

remote controls

What does an optoisolator do?

allows information to be transferred between circuits not sharing a common ground potential

Where are opto-isolators found?

medical equipment

In what common household item can you find infrared LEDs?

LED Computers

Where are LEDs not often used?

I'm not sure.

What is an example of a device that uses not free space optic communications?

I'm not sure.

What does an optoisolator don't do?

I'm not sure.


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.

What video game console uses infrared LEDs?

Nintendo Wii

What device uses infrared LEDs to measure oxygen saturation?

Pulse oximeters

Some flatbed scanners use what type of LED?

RGB LEDs

By using LEDs, scanners do not have to what?

warm-up

Grow lights use LEDs for what process?

increase photosynthesis in plants

What video game console doesn't use infrared LEDs?

I'm not sure.

non- What device uses infrared LEDs to measure oxygen saturation?

I'm not sure.

Some flatbed scanners use what type of what?

I'm not sure.


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.

What quality has LEDs been used as?

medium-quality

What LED has the flattest I/V curve above the knee?

Red

What LEDs have a very steep I/V curve?

Nitride-based LEDs

LED forward voltage is more current-dependent than what diode?

Zener

Zener diodes below what voltage are not widely available?

3 V

What quality hasn't LEDs been used as?

I'm not sure.

What LED has the least flattest I/V curve above the knee?

I'm not sure.

What LEDs have a not very steep I/V curve?

I'm not sure.

What LEDs don't have a very steep I/V curve?

I'm not sure.


The term "great power" was first used to represent the most important powers in Europe during the post-Napoleonic era. The "Great Powers" constituted the "Concert of Europe" and claimed the right to joint enforcement of the postwar treaties. The formalization of the division between small powers and great powers came about with the signing of the Treaty of Chaumont in 1814. Since then, the international balance of power has shifted numerous times, most dramatically during World War I and World War II. While some nations are widely considered to be great powers, there is no definitive list of them. In literature, alternative terms for great power are often world power or major power, but these terms can also be interchangeable with superpower.

What was the formalization of the division of small powers and great powers?

Treaty of Chaumont

During the post Napoleonic era where were the first Great Powers concentrated?

Europe

During what 2 wars was the balance of power shift most dramatic?

World War I and World War II

What is another term for Great Power?

superpower

Why was the term formalization and division first used?

I'm not sure.

Which international balance of power formally created the division between small and great powers?

I'm not sure.

In what year was the definitive list of powers signed?

I'm not sure.

For which post Napoleonic era has the balance of power shifted dramatically?

I'm not sure.

What is another term used in place of international balance of power?

I'm not sure.


A great power is a sovereign state that is recognized as having the ability and expertise to exert its influence on a global scale. Great powers characteristically possess military and economic strength, as well as diplomatic and soft power influence, which may cause middle or small powers to consider the great powers' opinions before taking actions of their own. International relations theorists have posited that great power status can be characterized into power capabilities, spatial aspects, and status dimensions. Sometimes the status of great powers is formally recognized in conferences such as the Congress of Vienna or an international structure such as the United Nations Security Council (China, France, Russia, the United Kingdom and the United States serve as the body's five permanent members). At the same time the status of great powers can be informally recognized in a forum such as the G7 which consists of Canada, France, Germany, Italy, Japan, the United Kingdom and the United States of America.

What do great powers usually have?

military and economic strength, as well as diplomatic and soft power influence

What are the permanent members of UN Security Council?

China, France, Russia, the United Kingdom and the United States

What are the countries in the G7?

Canada, France, Germany, Italy, Japan, the United Kingdom and the United States of America

What 3 factors have international relations theorists considered factors for great power status?

power capabilities, spatial aspects, and status dimensions

What great power has five permanent members?

I'm not sure.

What international structure exerts its influence on a global scale?

I'm not sure.

What has the United Nations Security Council characterized as comprising great power status?

I'm not sure.

What spatial aspects are Canada, France, Germany, Italy, Japan, the United Kingdom and the United States a part of?

I'm not sure.

In what conference are great powers opinions formally considered?

I'm not sure.


Early writings on the subject tended to judge states by the realist criterion, as expressed by the historian A. J. P. Taylor when he noted that "The test of a great power is the test of strength for war." Later writers have expanded this test, attempting to define power in terms of overall military, economic, and political capacity. Kenneth Waltz, the founder of the neorealist theory of international relations, uses a set of five criteria to determine great power: population and territory; resource endowment; economic capability; political stability and competence; and military strength. These expanded criteria can be divided into three heads: power capabilities, spatial aspects, and status.

Who wrote, "The test of a great power is the test of strength for war."?

A. J. P. Taylor

Whos was the founder of the neorealist theory of international relations?

Kenneth Waltz

What 5 criteria did neorealist use to determine great powers?

population and territory; resource endowment; economic capability; political stability and competence; and military strength

What 3 areas can summarize the great power determination?

power capabilities, spatial aspects, and status

What did the historian Kenneth Waltz note about great power?

I'm not sure.

With what terms did later writers define neorealist theory?

I'm not sure.

What term was used in early times to judge a state's political capacity?

I'm not sure.

What three groups can political capacity be divided into?

I'm not sure.

Who was the founder of the neorealist theory on the test of strength for war?

I'm not sure.


All states have a geographic scope of interests, actions, or projected power. This is a crucial factor in distinguishing a great power from a regional power; by definition the scope of a regional power is restricted to its region. It has been suggested that a great power should be possessed of actual influence throughout the scope of the prevailing international system. Arnold J. Toynbee, for example, observes that "Great power may be defined as a political force exerting an effect co-extensive with the widest range of the society in which it operates. The Great powers of 1914 were 'world-powers' because Western society had recently become 'world-wide'."

What do all states have?

geographic scope of interests, actions, or projected power

Who stated that "Great power may be defined as a political force exerting an effect co-extensive with the widest range of the society in which it operates. The Great powers of 1914 were 'world-powers"?

Arnold J. Toynbee

What type of powers should have actual influence throughout the scope of the prevailing international system?

great power

What type of power is restricted to its region?

regional power

What three things do all political forces have?

I'm not sure.

What should a Western society possess?

I'm not sure.

What is a range of society restricted to?

I'm not sure.

What were international systems called in 1914?

I'm not sure.

What political force was world-wide in 1914?

I'm not sure.


Other important criteria throughout history are that great powers should have enough influence to be included in discussions of political and diplomatic questions of the day, and have influence on the final outcome and resolution. Historically, when major political questions were addressed, several great powers met to discuss them. Before the era of groups like the United Nations, participants of such meetings were not officially named, but were decided based on their great power status. These were conferences which settled important questions based on major historical events. This might mean deciding the political resolution of various geographical and nationalist claims following a major conflict, or other contexts.

What discussion should great powers be included on?

political and diplomatic questions of the day

Historically, when would great powers meet?

when major political questions were addressed

What types of decisions would great powers reach?

political resolution of various geographical and nationalist claims following a major conflict, or other contexts

What criteria should groups like the UN have?

I'm not sure.

In the past when would officially named participants meet?

I'm not sure.

What is an example of something United Nations did to settle an issue?

I'm not sure.

What should geographical and nationalist claims have influence on?

I'm not sure.

What did criteria throughout history settle?

I'm not sure.


Lord Castlereagh, the British Foreign Secretary, first used the term in its diplomatic context, in a letter sent on February 13, 1814: "It affords me great satisfaction to acquaint you that there is every prospect of the Congress terminating with a general accord and Guarantee between the Great powers of Europe, with a determination to support the arrangement agreed upon, and to turn the general influence and if necessary the general arms against the Power that shall first attempt to disturb the Continental peace."

When did Lord Castlereagh first use the term Great Powers?

in a letter sent on February 13, 1814

What position did Lord Castlereagh hold?

British Foreign Secretary

What did Castlereagh determine as the last resort of great power's influence?

if necessary the general arms against the Power that shall first attempt to disturb the Continental peace

What member of Congress first used the term Great Powers?

I'm not sure.

When did Lord Castleereagh first use the term Continental peace?

I'm not sure.

What did the Great powers of Europe send in 1814?

I'm not sure.

What general influence was agreed upon in the letter sent in 1814?

I'm not sure.

What is the Great power turning against in the letter sent in 1814?

I'm not sure.


Of the five original great powers recognised at the Congress of Vienna, only France and the United Kingdom have maintained that status continuously to the present day, although France was defeated in the Franco-Prussian War and occupied during World War II. After the Congress of Vienna, the British Empire emerged as the pre-eminent power, due to its navy and the extent of its territories, which signalled the beginning of the Pax Britannica and of the Great Game between the UK and Russia. The balance of power between the Great Powers became a major influence in European politics, prompting Otto von Bismarck to say "All politics reduces itself to this formula: try to be one of three, as long as the world is governed by the unstable equilibrium of five great powers."

What 2 powers named in the 5 orignal great powers of the congress of vienna have maintained that status?

only France and the United Kingdom

What country lost Franco-Prussian war?

France

What country emerged as the pre-eminent power, due to its navy and the extent of its territories?

British Empire

Balance of power of great powers was a major influence on what continents politics?

European

Who stated that "All politics reduces itself to this formula: try to be one of three, as long as the world is governed by the unstable equilibrium of five great powers.?"

Otto von Bismarck

What two powers involved in the Franco-Prussian war have the same status today?

I'm not sure.

After WWII which country was the pre-eminent power?

I'm not sure.

What became a main influence for the Congress of Vienna?

I'm not sure.

By what formula are all great powers reduced?

I'm not sure.

What pre-eminent power lost the Franco-Prussian war?

I'm not sure.


Over time, the relative power of these five nations fluctuated, which by the dawn of the 20th century had served to create an entirely different balance of power. Some, such as the United Kingdom and Prussia (as the founder of the newly formed German state), experienced continued economic growth and political power. Others, such as Russia and Austria-Hungary, stagnated. At the same time, other states were emerging and expanding in power, largely through the process of industrialization. These countries seeking to attain great power status were: Italy after the Risorgimento, Japan after the Meiji Restoration, and the United States after its civil war. By the dawn of the 20th century, the balance of world power had changed substantially since the Congress of Vienna. The Eight-Nation Alliance was a belligerent alliance of eight nations against the Boxer Rebellion in China. It formed in 1900 and consisted of the five Congress powers plus Italy, Japan, and the United States, representing the great powers at the beginning of 20th century.

Was the power of the 5 countries constant?

relative power of these five nations fluctuated

What countries found their economic growth in early 20th century?

United Kingdom and Prussia

Which of the 5 powers were beginning to stagnate in early 20th century?

Russia and Austria-Hungary

What agreement replaced the Congress of Vienna?

Eight-Nation Alliance

What conflict was this agreement in opposition of?

Boxer Rebellion in China.

During the Risorgimento, what had changed since the Congress of Vienna?

I'm not sure.

What were other states doing through the political power process?

I'm not sure.

What was the US seeking to do after the Meiji Restoration?

I'm not sure.

What nation alliance was formed to be against the Meiji Restoration?

I'm not sure.

What did the balance of world power consist of after 1900?

I'm not sure.


Shifts of international power have most notably occurred through major conflicts. The conclusion of the Great War and the resulting treaties of Versailles, St-Germain, Neuilly, Trianon and Sèvres witnessed the United Kingdom, France, Italy, Japan and the United States as the chief arbiters of the new world order. In the aftermath of World War I the German Empire was defeated, the Austria-Hungarian empire was divided into new, less powerful states and the Russian Empire fell to a revolution. During the Paris Peace Conference, the "Big Four"—France, Italy, United Kingdom and the United States—held noticeably more power and influence on the proceedings and outcome of the treaties than Japan. The Big Four were leading architects of the Treaty of Versailles which was signed by Germany; the Treaty of St. Germain, with Austria; the Treaty of Neuilly, with Bulgaria; the Treaty of Trianon, with Hungary; and the Treaty of Sèvres, with the Ottoman Empire. During the decision-making of the Treaty of Versailles, Italy pulled out of the conference because a part of its demands were not met and temporarily left the other three countries as the sole major architects of that treaty, referred to as the "Big Three".

What marked the conclusion of The Great War?

treaties of Versailles, St-Germain, Neuilly, Trianon and Sèvres

Who were  the chief arbiters of the new world order?

United Kingdom, France, Italy, Japan and the United States

Who created the Treaty of Versailles?

Big Three

Who were the big four?

France, Italy, United Kingdom and the United States

What resulted after the end of the new world order?

I'm not sure.

What empire was defeated after the Big Four?

I'm not sure.

When did Austria fall to revolution?

I'm not sure.

During the Great War which four countries had more power and influence?

I'm not sure.

When did The United States pull out of the conference temporarily?

I'm not sure.


The victorious great powers also gained an acknowledgement of their status through permanent seats at the League of Nations Council, where they acted as a type of executive body directing the Assembly of the League. However, the Council began with only four permanent members—the United Kingdom, France, Italy, and Japan—because the United States, meant to be the fifth permanent member, left because the US Senate voted on 19 March 1920 against the ratification of the Treaty of Versailles, thus preventing American participation in the League.

Who were the four permanent members of the League of Nations Council?

United Kingdom, France, Italy, and Japan

Why was United Stated excluded from League of Nations Council?

against the ratification of the Treaty of Versailles, thus preventing American participation in the League

When did US Senate vote against treaty of versailles ratification?

19 March 1920

What organiztion acted as acknowledgement of status of great powers?

League of Nations Council

When did the League of Nations council vote against the Treaty of Versailles ratification?

I'm not sure.

Why was France excluded from the League of Nations Council?

I'm not sure.

What four countries were permanent members of the Senate?

I'm not sure.

What council voted against ratification of the Treaty of Versailles?

I'm not sure.

What did voting against the Assembly of the League prevent?

I'm not sure.


When World War II started in 1939, it divided the world into two alliances—the Allies (the United Kingdom and France at first in Europe, China in Asia since 1937, followed in 1941 by the Soviet Union, the United States); and the Axis powers consisting of Germany, Italy and Japan.[nb 1] During World War II, the United States, United Kingdom, and Soviet Union controlled Allied policy and emerged as the "Big Three". The Republic of China and the Big Three were referred as a "trusteeship of the powerful"  and were recognized as the Allied "Big Four" in Declaration by United Nations in 1942. These four countries were referred as the "Four Policemen" of the Allies and considered as the primary victors of World War II. The importance of France was acknowledged by their inclusion, along with the other four, in the group of countries allotted permanent seats in the United Nations Security Council.

When did World War II start?

How many groups were involved in conflict of World War II?

two alliances

Who made up the Axis powers?

Germany, Italy and Japan

Who were the winners of World War II?

Allies

The winners of World War II along with France were allotted permanent seats for what organization?

United Nations Security Council

What trusteeship of the powerful started in 1939?

I'm not sure.

Who made up the permanent seats alliances since 1937?

I'm not sure.

What was Germany, Italy and Japan  and France recognized as by the UN in 1942?

I'm not sure.

What were four alliances in WWII referred to?

I'm not sure.

Who was part of the inclusion powers?

I'm not sure.


Since the end of the World Wars, the term "great power" has been joined by a number of other power classifications. Foremost among these is the concept of the superpower, used to describe those nations with overwhelming power and influence in the rest of the world. It was first coined in 1944 by William T.R. Fox and according to him, there were three superpowers: the British Empire, the United States, and the Soviet Union. But by the mid-1950s the British Empire lost its superpower status, leaving the United States and the Soviet Union as the world's superpowers.[nb 2] The term middle power has emerged for those nations which exercise a degree of global influence, but are insufficient to be decisive on international affairs. Regional powers are those whose influence is generally confined to their region of the world.

What is a superpower?

nations with overwhelming power and influence in the rest of the world

Who first used the term superpower?

William T.R. Fox

Who were the three original superpowers?

British Empire, the United States, and the Soviet Union

Who lost their superpower status in 1950s?

British Empire

What are middle powers?

those nations which exercise a degree of global influence, but are insufficient to be decisive on international affairs

Who first used the term overwhelming influence?

I'm not sure.

What are the regional powers according to William T. R. Fox?

I'm not sure.

When did the Soviet Union lose its superpower status?

I'm not sure.

How many original middle powers are there?

I'm not sure.

Which nations have a degree of overwhelming power but are not decisive internationally?

I'm not sure.


During the Cold War, the Asian power of Japan and the European powers of the United Kingdom, France, and West Germany rebuilt their economies. France and the United Kingdom maintained technologically advanced armed forces with power projection capabilities and maintain large defence budgets to this day. Yet, as the Cold War continued, authorities began to question if France and the United Kingdom could retain their long-held statuses as great powers. China, with the world's largest population, has slowly risen to great power status, with large growth in economic and military power in the post-war period. After 1949, the Republic of China began to lose its recognition as the sole legitimate government of China by the other great powers, in favour of the People's Republic of China. Subsequently, in 1971, it lost its permanent seat at the UN Security Council to the People's Republic of China.

During the cold war, what European powers rebuilt their ecomonies?

United Kingdom, France, and West Germany

By what year was China beginning to lose its hold as sole legitimate government?

When did China lose its permanent seat at UN security council?

What powers rebuilt their economies during 1949?

I'm not sure.

What two countries status as military powers was questioned?

I'm not sure.

When did West Germany lose its permanent UN security council seat?

I'm not sure.

After the cold war, which country began to lose its status as sole legitimate government?

I'm not sure.

What did China and Japan maintain to this day?

I'm not sure.


According to Joshua Baron – a "researcher, lecturer, and consultant on international conflict" – since the early 1960s direct military conflicts and major confrontations have "receded into the background" with regards to relations among the great powers. Baron argues several reasons why this is the case, citing the unprecedented rise of the United States and its predominant position as the key reason. Baron highlights that since World War Two no other great power has been able to achieve parity or near parity with the United States, with the exception of the Soviet Union for a brief time. This position is unique among the great powers since the start of the modern era (the 16th century), where there has traditionally always been "tremendous parity among the great powers". This unique period of American primacy has been an important factor in maintaining a condition of peace between the great powers.

Since what time has military conflicts receded?

What country has risen above other superpowers?

United States

Since what century has there always been parity in powers?

modern era (the 16th century)

Who's primacy has factored into maintaining peace among powers?

American

Since what time has there been direct military conflicts among countries?

I'm not sure.

What has been important factor of the great powers receding into the background?

I'm not sure.

Since the 1960's what power was briefly equal in parity with the US?

I'm not sure.

What country has been involved in major confrontations among powers?

I'm not sure.

What has the Soviet Union mentioned about relations between the great powers?

I'm not sure.


Another important factor is the apparent consensus among Western great powers that military force is no longer an effective tool of resolving disputes among their peers. This "subset" of great powers – France, Germany, Japan, the United Kingdom and the United States – consider maintaining a "state of peace" as desirable. As evidence, Baron outlines that since the Cuban missile crisis (1962) during the Cold War, these influential Western nations have resolved all disputes among the great powers peacefully at the United Nations and other forums of international discussion.

What formerly effective tool for international disputes is no longer effective among peer powers?

military force

What great powers have maintained peace?

France, Germany, Japan, the United Kingdom and the United States

Where have the powers maintained peace in recent years?

United Nations and other forums

What was the last crisis during cold war to escalate world powers?

Cuban missile crisis (1962

What countries agree that military force is effective to resolve disputes?

I'm not sure.

During what event did great powers use military force?

I'm not sure.

Who mentioned that Western great powers still use military force to resolve disputes?

I'm not sure.

What formerly effective tool for the Cuban missile crisis is no longer effective?

I'm not sure.

Where have western nations discussed using military force?

I'm not sure.


China, France, Russia, the United Kingdom and the United States are often referred to as great powers by academics due to "their political and economic dominance of the global arena". These five nations are the only states to have permanent seats with veto power on the UN Security Council. They are also the only recognized "Nuclear Weapons States" under the Nuclear Non-Proliferation Treaty, and maintain military expenditures which are among the largest in the world. However, there is no unanimous agreement among authorities as to the current status of these powers or what precisely defines a great power. For example, sources have at times referred to China, France, Russia and the United Kingdom as middle powers.

What countries are recognized as Nuclear Weapons States?

China, France, Russia, the United Kingdom and the United States

How many countries are permanent seats on the UN Security Council?

five

What other countries are referred to as middle powers?

China, France, Russia and the United Kingdom

What treaty addresses nuclear weapons?

Nuclear Non-Proliferation Treaty

What treaty addresses global political and economic dominance?

I'm not sure.

What five countries are referred to as middle powers?

I'm not sure.

Why Are China, France, Russia, the UK and the US seen as by middle powers?

I'm not sure.

What is there not consensus on among nations regarding powers?

I'm not sure.

What do the five nations have as middle powers on the UN Security Council?

I'm not sure.


Japan and Germany are great powers too, though due to their large advanced economies (having the third and fourth largest economies respectively) rather than their strategic and hard power capabilities (i.e., the lack of permanent seats and veto power on the UN Security Council or strategic military reach). Germany has been a member together with the five permanent Security Council members in the P5+1 grouping of world powers. Like China, France, Russia and the United Kingdom; Germany and Japan have also been referred to as middle powers.

What countries are great powers mostly based on economic reasons?

Japan and Germany

Due to lack of strategic and hard power, countries are excluded from what?

UN Security Council

What is the name for the grouping of countries of China, France, Russia and the United Kingdom; Germany and Japan?

middle powers

What two countries are great powers because of their hard power capabilities?

I'm not sure.

What grouping of world powers has Japan been a member of?

I'm not sure.

What benefits do middle power countries have as permanent members at the UN?

I'm not sure.

How large are France and Russia's economies?

I'm not sure.

What are the five permanent Security Council Members lacking militarily?

I'm not sure.


In addition to those contemporary great powers mentioned above, Zbigniew Brzezinski and Malik Mohan consider India to be a great power too. Although unlike the contemporary great powers who have long been considered so, India's recognition among authorities as a great power is comparatively recent. However, there is no collective agreement among observers as to the status of India, for example, a number of academics believe that India is emerging as a great power, while some believe that India remains a middle power.

Zbigniew Brzezinski and Malik Mohan consider what country to be a great power too?

India

Many academics debate the status of this country as a power?

India

Is there agreement on the status of all powers?

no collective agreement

Who have recently recognized contemporary great powers?

I'm not sure.

What have observers long considered about India's status?

I'm not sure.

What do academics believe contemporary great powers remain?

I'm not sure.

What is the consensus about India's status among great powers?

I'm not sure.

What is one type of power some world powers view as India's status in the world?

I'm not sure.


Milena Sterio, American expert of international law, includes the former axis powers (Germany, Italy and Japan) and India among the great powers along with the permanent members of the UNSC. She considers Germany, Japan and Italy to be great powers due to their G7 membership and because of their influence in regional and international organizations.  Various authors describe Italy as an equal major power, while others view Italy as an "intermittent great power" or as "the least of the great powers".

Milena Sterio includes what former axis powers among great powers?

Germany, Italy and Japan

What emerging power is considered a great power?

India

What G7 members are among great powers?

Germany, Japan and Italy

Which country is debated as intermittent and/or least of great powers?

Italy

What international organization members are considered great powers?

I'm not sure.

What separate status are Germany, Italy and Japan given by various authors?

I'm not sure.

What permanent member of the UNSC is considered the least of the great powers?

I'm not sure.

What former axis powers do various authors include as great powers?

I'm not sure.

Why does Milena Sterio consider UNSC members great powers?

I'm not sure.


With continuing European integration, the European Union is increasingly being seen as a great power in its own right, with representation at the WTO and at G8 and G-20 summits. This is most notable in areas where the European Union has exclusive competence (i.e. economic affairs). It also reflects a non-traditional conception of Europe's world role as a global "civilian power", exercising collective influence in the functional spheres of trade and diplomacy, as an alternative to military dominance. The European Union is a supranational union and not a sovereign state, and has limited scope in the areas of foreign affairs and defence policy. These remain largely with the member states of the European Union, which include the three great powers of France, Germany and the United Kingdom (referred to as the "EU three").

What organization is often seen as a great power in addition to member counties?

European Union

What other tools are used as alternative to military force?

trade and diplomacy

How many great powers are members of Europian Union?

three

What summits does EU have membership?

WTO and at G8 and G-20

Where does Europe use its military dominance?

I'm not sure.

As a supranational union, what are the UK's limits?

I'm not sure.

How many great powers are members of the WTO?

I'm not sure.

At what summits does Germany have representation?

I'm not sure.

In what area is the WTO exclusively competent?

I'm not sure.


Referring to great power relations pre-1960, Joshua Baron highlights that starting from around the 16th century and the rise of several European great powers, military conflicts and confrontations was the defining characteristic of diplomacy and relations between such powers. "Between 1500 and 1953, there were 64 wars in which at least one great power was opposed to another, and they averaged little more than five years in length. In approximately a 450-year time frame, on average at least two great powers were fighting one another in each and every year." Even during the period of Pax Britannica (or "the British Peace") between 1815 and 1914, war and military confrontations among the great powers was still a frequent occurrence. In fact, Joshua Baron points out that, in terms of militarized conflicts or confrontations, the UK led the way in this period with nineteen such instances against; Russia (8), France (5), Germany/Prussia (5) and Italy (1).

How many wars occured between 1500s and 1953?

For bout how many years was an average of one great power fighting another each year?

What country had the most conflicts from 1500s through mid 20th century?

UK

What span was the Pax Britannica?

between 1815 and 1914

Between 1815 and 1914, how many acts of diplomacy were there and with what countries?

I'm not sure.

How many wars occurred pre-1960, that averaged about 5 years?

I'm not sure.

Between 1815-1914 what country had the most defining characteristics of diplomacy?

I'm not sure.

In the 16th century, how many great powers were fighting each other in every year?

I'm not sure.

During what time frame was diplomacy frequent among the great powers?

I'm not sure.


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.

What is a group of endothermic vertebrates characterised by feathers and toothless beaked jaws?

Birds

What is the smallest bird?

bee hummingbird

What is the largest bird?

ostrich

What is the size of the smallest bird?

5 cm (2 in)

What is the size of the largest bird?

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.

What are the last surviving dinosaurs, according o the fossil record?

birds

When did true birds first appear?

Cretaceous period

Name an example of an early stem-bird.

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.

What makes birds uniquely adapted for flight?

digestive and respiratory systems

What type of bird particularly played an important part in the inception of Darwin's theory of evolution by natural selection?

Darwin's finches

Which part of the bird developed from forelimbs?

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.

Which type of birds are among the most intelligent animals?

corvids and parrots

How to birds produce offspring?

by laying eggs which are fertilized through sexual reproduction

Where are eggs usually laid?

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.

Which birds are popular as pets?

Songbirds, parrots

What is guano?

bird excrement

What is the name of bird excrement?

Guano

What is harvested for use as fertilizer?

Guano

How many species of birds have become extinct as a result of human activity?


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.

Besides Aves, what group contains the only living representatives of the reptile clade Archosauria?

clade Crocodilia

Who defined Aves to include only the crown group of the set of modern birds?

Gauthier

What is a sister group to Aves?

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.

What evidence leads most scientists to accept that birds are a specialized subgroup of theropod dinosaurs?

fossil and biological evidence

What is a group of theropods which include dromaeosaurs and oviraptorids?

Maniraptora

Recent discoveries in what country demonstrate many small theropod feathered dinosaurs.

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.

What are the closest relatives of the deinonychosaurs?

flying theropods

What are the closest relatives of flying theropods?

deinonychosaurs

Dromaeosaurids and troodontids are members of what group?

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.

What is known as one of the first transitional fossils to be found?

Late Jurassic Archaeopteryx

What was the first fossil to display both clearly traditional reptilian characteristics?

Archaeopteryx

Fossils with teeth, clawed fingers and a long lizard-like tail have what type of characteristics?

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.

The Oxfordian stage is also known as what?

late Jurassic period

How long ago was the late Jurassic period?

about 160 million years ago

Avian species such as Anchiornis huxleyi and Xiaotingia zhengi are from which time period?

late Jurassic period

What may have been used in aerial maneuvering?

hind wings


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.

During which time period did avialans diversify into a wide variety of forms?

Cretaceous Period

Which forms retained the long bony tails of their ancestors?

Archaeopteryx and Jeholornis

When did the ancestor of all modern birds evolve a better sense of smell?

late Cretaceous

How long ago was the late Cretaceous period?

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.

What were the first large, diverse lineage of short-tailed avialans to evolve?

enantiornithes

Because of the construction of their shoulder bones, what were the enantiornithes called?

opposite birds

What was the dominant group of avialans during the Cretaceous period?

enantiornithes

When did enantiornithes become extinct?

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.

What does Euornithes mean?

true birds

Why does Euornithes mean "true birds?"

because they include the ancestors of modern birds

What group became the first avialans to develop true pygostyle and a fully mobile fan of tail feathers?

Euornithes

What may have replaced the "hind wing" as the primary mode of aerial maneuverability?

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.

All modern birds lie within which crown group?

Aves

What is another name for Aves?

Neornithes

The two subdivisions of what group include Palaeognathae and Neognathae?

Aves

What is the number range of living bird species?

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.

What was the earliest divergence within the Neognathes?

Galloanserae

What is the superorder containing the Anseriformes?

Galloanserae

Ducks, geese, swans and screamers are part of which group?

Anseriformes

The pheasants, grouse and their allies form which group?

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.

Sibley and Ahlquist' Phylogeny and Classification of Birds is a landmark work on the classification of what animals?

birds

What do scientists disagree about?

relationships between the orders themselves

What do scientists tend to agree on?

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).

Birds live on how many continents?

seven

Highest bird diversity occurs in which regions?

tropical

Some penguins have been recording diving up to how many feet?

Some seabird species only come ashore for what purpose?

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.

The ring-necked pheasant has been introduced as what kind of bird?

game bird

Why have some species spread naturally far beyond their original ranges?

agricultural practices created suitable new habitat

Where have many birds established breeding populations?

in areas to which they have been introduced by humans


The skeleton consists of very lightweight bones. They have large air-filled cavities (called pneumatic cavities) which connect with the respiratory system. The skull bones in adults are fused and do not show cranial sutures. The orbits are large and separated by a bony septum. The spine has cervical, thoracic, lumbar and caudal regions with the number of cervical (neck) vertebrae highly variable and especially flexible, but movement is reduced in the anterior thoracic vertebrae and absent in the later vertebrae. The last few are fused with the pelvis to form the synsacrum. The ribs are flattened and the sternum is keeled for the attachment of flight muscles except in the flightless bird orders. The forelimbs are modified into wings.

What consists of very lightweight bones?

The skeleton

What does the skeleton consist of?

very lightweight bones

What are pneumatic cavities?

large air-filled cavities

What are large air-filled cavities that connect to the respiratory system?

pneumatic cavities

What is formed when vertebrae are fused with the pelvis?

synsacrum


Like the reptiles, birds are primarily uricotelic, that is, their kidneys extract nitrogenous waste from their bloodstream and excrete it as uric acid instead of urea or ammonia through the ureters into the intestine. Birds do not have a urinary bladder or external urethral opening and (with exception of the ostrich) uric acid is excreted along with feces as a semisolid waste. However, birds such as hummingbirds can be facultatively ammonotelic, excreting most of the nitrogenous wastes as ammonia. They also excrete creatine, rather than creatinine like mammals. This material, as well as the output of the intestines, emerges from the bird's cloaca. The cloaca is a multi-purpose opening: waste is expelled through it, most birds mate by joining cloaca, and females lay eggs from it. In addition, many species of birds regurgitate pellets. Males within Palaeognathae (with the exception of the kiwis), the Anseriformes (with the exception of screamers), and in rudimentary forms in Galliformes (but fully developed in Cracidae) possess a penis, which is never present in Neoaves. The length is thought to be related to sperm competition. When not copulating, it is hidden within the proctodeum compartment within the cloaca, just inside the vent. The digestive system of birds is unique, with a crop for storage and a gizzard that contains swallowed stones for grinding food to compensate for the lack of teeth. Most birds are highly adapted for rapid digestion to aid with flight. Some migratory birds have adapted to use protein from many parts of their bodies, including protein from the intestines, as additional energy during migration.

What is it called when a bird's kidneys extract nitrogenous waste from their bloodstream and secrete it as uric acid?

uricotelic

Which bid has a urinary bladder or external urethral opening?

ostrich

What is a multi-purpose opening on birds?

cloaca

How do most birds mate?

by joining cloaca

What aids birds with flight?

rapid digestion


Birds have one of the most complex respiratory systems of all animal groups. Upon inhalation, 75% of the fresh air bypasses the lungs and flows directly into a posterior air sac which extends from the lungs and connects with air spaces in the bones and fills them with air. The other 25% of the air goes directly into the lungs. When the bird exhales, the used air flows out of the lung and the stored fresh air from the posterior air sac is simultaneously forced into the lungs. Thus, a bird's lungs receive a constant supply of fresh air during both inhalation and exhalation. Sound production is achieved using the syrinx, a muscular chamber incorporating multiple tympanic membranes which diverges from the lower end of the trachea; the trachea being elongated in some species, increasing the volume of vocalizations and the perception of the bird's size.

Which animal has one of the most complex respiratory system of all animal groups?

Birds

Upon inhalation, what percentage of fresh air bypasses the lungs and flows directly into a posterior air sac?

Where does the other 25 percent of fresh air go?

directly into the lungs

Sound production is achieved using what muscular chamber?

syrinx

What is the syrinx?

a muscular chamber incorporating multiple tympanic membranes


The avian circulatory system is driven by a four-chambered, myogenic heart contained in a fibrous pericardial sac. This pericardial sac is filled with a serous fluid for lubrication. The heart itself is divided into a right and left half, each with an atrium and ventricle. The atrium and ventricles of each side are separated by atrioventricular valves which prevent back flow from one chamber to the next during contraction. Being myogenic, the heart's pace is maintained by pacemaker cells found in the sinoatrial node, located on the right atrium. The sinoatrial node uses calcium to cause a depolarizing signal transduction pathway from the atrium through right and left atrioventricular bundle which communicates contraction to the ventricles. The avian heart also consists of muscular arches that are made up of thick bundles of muscular layers. Much like a mammalian heart, the avian heart is composed of endocardial, myocardial and epicardial layers. The atrium walls tend to be thinner than the ventricle walls, due to the intense ventricular contraction used to pump oxygenated blood throughout the body. Avian hearts are generally larger than mammalian hearts when compared to body mass. This adaptation allows more blood to be pumped to meet the high metabolic need associated with flight.

The avian circulatory system is driven by what?

four-chambered, myogenic heart

Where is the heart contained in the avian circulatory system?

fibrous pericardial sac

What lubricates the pericardial sac?

serous fluid

Why are Avian hearts larger than mammalian hearts when compared to body mass?

allows more blood to be pumped


Birds have a very efficient system for diffusing oxygen into the blood; birds have a ten times greater surface area to gas exchange volume than mammals. As a result, birds have more blood in their capillaries per unit of volume of lung than a mammal. The arteries are composed of thick elastic muscles to withstand the pressure of the ventricular constriction, and become more rigid as they move away from the heart. Blood moves through the arteries, which undergo vasoconstriction, and into arterioles which act as a transportation system to distribute primarily oxygen as well as nutrients to all tissues of the body. As the arterioles move away from the heart and into individual organs and tissues they are further divided to increase surface area and slow blood flow. Travelling through the arterioles blood moves into the capillaries where gas exchange can occur. Capillaries are organized into capillary beds in tissues, it is here that blood exchanges oxygen for carbon dioxide waste. In the capillary beds blood flow is slowed to allow maximum diffusion of oxygen into the tissues. Once the blood has become deoxygenated it travels through venules then veins and back to the heart. Veins, unlike arteries, are thin and rigid as they do not need to withstand extreme pressure. As blood travels through the venules to the veins a funneling occurs called vasodilation bringing blood back to the heart. Once the blood reaches the heart it moves first into the right atrium, then the right ventricle to be pumped through the lungs for further gas exchange of carbon dioxide waste for oxygen. Oxygenated blood then flows from the lungs through the left atrium to the left ventricle where it is pumped out to the body.

Why are birds' arteries composed of thick elastic muscles?

to withstand the pressure of the ventricular constriction

What moves through the arteries?

Blood

What is organized into capillary beds in tissues?

Capillaries

What is the funneling that occurs that brings blood back to the heart?

vasodilation


The nervous system is large relative to the bird's size. The most developed part of the brain is the one that controls the flight-related functions, while the cerebellum coordinates movement and the cerebrum controls behaviour patterns, navigation, mating and nest building. Most birds have a poor sense of smell with notable exceptions including kiwis, New World vultures and tubenoses. The avian visual system is usually highly developed. Water birds have special flexible lenses, allowing accommodation for vision in air and water. Some species also have dual fovea. Birds are tetrachromatic, possessing ultraviolet (UV) sensitive cone cells in the eye as well as green, red and blue ones. This allows them to perceive ultraviolet light, which is involved in courtship. Birds have specialized light-sensing cells deep in their brains that respond to light without input from eyes or other sensory neurons. These photo-receptive cells in the hypothalamus are involved in detecting the longer days of spring, and thus regulate breeding activities.

Which bird system is large relative to a bird's size?

nervous system

What is tetrachromatic?

possessing ultraviolet (UV) sensitive cone cells in the eye as well as green, red and blue ones

Why do birds need to perceive ultraviolet light?

courtship

What regulates breeding activities?

photo-receptive cells in


Many birds show plumage patterns in ultraviolet that are invisible to the human eye; some birds whose sexes appear similar to the naked eye are distinguished by the presence of ultraviolet reflective patches on their feathers. Male blue tits have an ultraviolet reflective crown patch which is displayed in courtship by posturing and raising of their nape feathers. Ultraviolet light is also used in foraging—kestrels have been shown to search for prey by detecting the UV reflective urine trail marks left on the ground by rodents. The eyelids of a bird are not used in blinking. Instead the eye is lubricated by the nictitating membrane, a third eyelid that moves horizontally. The nictitating membrane also covers the eye and acts as a contact lens in many aquatic birds. The bird retina has a fan shaped blood supply system called the pecten. Most birds cannot move their eyes, although there are exceptions, such as the great cormorant. Birds with eyes on the sides of their heads have a wide visual field, while birds with eyes on the front of their heads, such as owls, have binocular vision and can estimate the depth of field. The avian ear lacks external pinnae but is covered by feathers, although in some birds, such as the Asio, Bubo and Otus owls, these feathers form tufts which resemble ears. The inner ear has a cochlea, but it is not spiral as in mammals.

What covers the eye and acts as a contact lens in many aquatic birds?

nictitating membrane

What is the fan shaped blood supply system in a bird's retina?

pecten

Which birds have a wide visual field?

Birds with eyes on the sides of their heads

What kind of vision do owls have?

binocular vision

Where is a bird's cochlea located?

inner ear


A dearth of field observations limit our knowledge, but intraspecific conflicts are known to sometimes result in injury or death. The screamers (Anhimidae), some jacanas (Jacana, Hydrophasianus), the spur-winged goose (Plectropterus), the torrent duck (Merganetta) and nine species of lapwing (Vanellus) use a sharp spur on the wing as a weapon. The steamer ducks (Tachyeres), geese and swans (Anserinae), the solitaire (Pezophaps), sheathbills (Chionis), some guans (Crax) and stone curlews (Burhinus) use a bony knob on the alular metacarpal to punch and hammer opponents. The jacanas Actophilornis and Irediparra have an expanded, blade-like radius. The extinct Xenicibis was unique in having an elongate forelimb and massive hand which likely functioned in combat or defence as a jointed club or flail. Swans, for instance, may strike with the bony spurs and bite when defending eggs or young.

What is known to sometimes result in injury or death?

intraspecific conflicts

What is another name for Anhimidae?

screamers

What is another name for steamer ducks?

Tachyeres

What do stone curlews use to punch and hammer opponents?

bony knob on the alular metacarpal


Feathers are a feature characteristic of birds (though also present in some dinosaurs not currently considered to be true birds). They facilitate flight, provide insulation that aids in thermoregulation, and are used in display, camouflage, and signaling. There are several types of feathers, each serving its own set of purposes. Feathers are epidermal growths attached to the skin and arise only in specific tracts of skin called pterylae. The distribution pattern of these feather tracts (pterylosis) is used in taxonomy and systematics. The arrangement and appearance of feathers on the body, called plumage, may vary within species by age, social status, and sex.

What is a feature characteristic of birds?

Feathers

What feature of a bird facilitate flight?

Feathers

What is pterylae?

specific tracts of skin