question: Why do we use dogs instead of technology for smelling. They seem very unreliable.
comment: A well trained dog is both incredibly reliable and an incredibly sensitive instrument for picking up odors. Depending on the breed, a dog's olfactory sensors (smell receptors) outnumber humans by 50 times, and the part of their brain dedicated to analyzing information from the olfactory sensors is 40 times larger than the comparable area in human brains. Robot/machine noses do exist, but they tend to be good for limited applications, and can get "confused" easily. For example, they generally must be tuned to pick up a specific molecule in a specific ambient concentration to have a positive read, and they can be overwhelmed by similar molecular compounds or otherwise produce false positives for any number of reasons. Current technology for many (most?) smell-based investigations are simply not as advanced as what a dog possesses naturally.
passages: There are hopes that advanced technology could do everything from testing perfumes to helping detect cancer or explosives by detecting specific scents, but artificial noses are still problematic. The complex nature of the human nose, its ability to detect even the most subtle of scents, is at the present difficult to replicate.
   Nosework
  
  Section::::Governing Bodies.
  
  National Association of Canine Scent Work (NACSW)
  
  NACSW is the oldest governing body in Nosework, established in the mid-2000s. K9 Nosework was created by professional detection dog handlers and trainers: Ron Gaunt, Amy Herot and Jill Marie O’Brien.
  
  United Kennel Club (UKC) Nosework
  
  UKC was the second organization to become a sanctioning body for nosework trials. Official trials are set to begin after January 1, 2015.
  
  Sport Detection Dog Association (SDDA)
  
  The SDDA is the first Canadian sanctioning body for nosework. Established in 2013, their first trial in western Canada took place in October 2014.
   Olfaction of dogs is used for a long time by the police (location of drug, of explosives, of weapon, body of missing persons, criminals' identification) or the services of rescue (bodies buried under avalanches). From 1910, a dog handler Friedo Schmidt describes in his book Verbrecherspur und Polizeihund («The criminal links and the police dog») how smells left by a criminal on a crime scene can be stocked in glassy jars for identification for purposes.
   One type of proposed machine olfaction technology is via gas sensor array instruments capable of detecting, identifying, and measuring volatile compounds. However, a critical element in the development of these instruments is pattern analysis, and the successful design of a pattern analysis system for machine olfaction requires a careful consideration of the various issues involved in processing multivariate data: signal-preprocessing, feature extraction, feature selection, classification, regression, clustering, and validation. Another challenge in current research on machine olfaction is the need to predict or estimate the sensor response to aroma mixtures. Some pattern recognition problems in machine olfaction such as odor classification and odor localization can be solved by using time series kernel methods.
   In 2000, AromaJet developed a scent-generating device prototype called Pinoke. No new announcements have been made since December 2000.
  
  In 2003, TriSenx (founded in 1999) launched a scent-generating device called Scent Dome, which by 2004 was tested by the UK internet service provider Telewest. This device was about the size of a teapot and could generate up to 60 different smells by releasing particles from one or more of 20 liquid-filled odor capsules. Computers fitted with a Scent Dome unit used software to recognize smell identifying codes embedded in an email or web page.
   The odor used is a specific scents that dogs are hunting for. Unlike many professional detection dogs, all odors used in nosework are legal to carry and own. Each governing body sets their own standard for which odors are the target odors and what levels they are paired with.
  
  The odor is often dripped on a cotton swab, which is then hidden in a search area.
  
  NACSW
  
  NW 1- Birch – ("Betula Lenta")
  
  NW 2- Birch and/or Anise – ("Pimpinella Anisum")
  
  NW 3- Birch, Anise and/or Clove – ("Eugenia Caryophylatta")
   In 2005, researchers from the University of Huelva developed XML Smell, a protocol of XML that can transmit smells. The researchers also developed a scent-generating device and worked on miniaturising its size. Also in 2005, Thanko launched P@D Aroma Generator, a USB device that comes with 3 different cartridges for different smells.
  
  In 2005, Japanese researchers announced that they are working on a 3D television with touch and smell that would be commercially available on the market by the year 2020.
  
  Section::::History.:2010s.
  
  During ThinkNext 2010, the Israeli company Scentcom featured a demo of its scent-generating device.
   Detection dogs are utilized all over airports specifically in baggage claim sections. The role of a detection dog is to prevent any substance such as illegal drugs or explosives to further enter the facility or leave it. The accuracy and physical capacity of these dogs has raised concerns and has led to the creation of sniffer devices. Similarly to dogs, this device also known as "chemical sniffers" or "electronic noses" is used to detect any trace of drugs and explosives. Odor, although not commonly thought to be connected with an individual's privacy, is unique to every individual. Every individual has a characteristic odor known as the “body odor signature” which can be used to identify gender, sexual orientation, health, diet, and so on. It can reveal emotions like fear and happiness and is viewed as a biological footprint. 
   In 2010, the Norwegian film "Kurt Josef Wagle And The Legend of the Fjord Witch" by director Tommy Wirkola was released to cinemas with scratch and sniff cards that the audience could use while watching the movie. One year later, the American film "" by director Robert Rodriguez used the same idea, advertised as "4D Aroma-Scope".
  
  There have been further attempts to develop similar systems for the use with television or advertising screens using gel pellets or inkjet printers to spray small amounts of scent.
  
  Section::::Portrayals.
  
  Section::::Portrayals.:April Fools' joke.
   In 2013, Amy Radcliffe, a Master's student in the Textile Futures department of Central Saint Martins, London introduced a prototype of a desktop device to record aromas. For the project, she drew on headspace technology pioneered in the 1980s by Roman Kaiser to capture smells in the air around certain objects.
   The Scent Transfer unit has undergone rigorous scientific testing including at Oak Ridge National Laboratory. It has been upheld on appeal in both State and Federal Courts in the 9th circuit as reliable scientific equipment. There are currently more than 400 units being used by Federal, State and Local law enforcement handlers across the US and abroad.
   Section::::Criticism.:Accuracy.:United States.
  
  In 2011, the "Chicago Tribune" claimed that detection dogs responses are influenced by the biases and behaviors of their handlers, which can hinder accuracy. Another factor that affects accuracy is residual odors. Residual odors can linger even after illegal materials have been removed from a particular area, and can lead to negative detection alerts. Additionally, very few states have mandatory training, testing, or certification standards for detection dogs. This leaves people to question whether they are truly equipped to carry out searches.
  
  Section::::Criticism.:Civil rights.
   One notable quality of detection dogs is that they are able to discern individual scents even when the scents are combined or masked by other odors. Many items that dogs can detect can be disguised when covered by multiple scents. Detection dogs help uncover these items. In 2002, a detection dog foiled a woman's attempt to smuggle marijuana into an Australian prison in Brisbane. The marijuana had been inserted into a balloon, which was smeared with coffee, pepper and petroleum jelly and then placed in her bra. 
  
  Section::::Functions.:Bed bug detection dogs.
   United States Canine Scent Sports
  
  New fun organization that sanctions Scent Work trials. They have the classic 4 element searches/classes : Interior, vehicles, exterior and container. They also have 5 Game Classes : Heaps O'Hides, Go The Distance, Scenting Sweepstakes, LudicrouSpeed and Team Spirit.
  
  National Association of Canine Scent Work (NACSW)
  
  Australian Canine Scent Work (ACSW)
  
  ACSW is the only governing body for K9 Nosework in Australia, established by Marion Brand of K9 NoseTime (www.k9nosetime.com) in November 2014. The ACSW is the only official sanctioning and organizing body for K9 Nose Work® titles and ORTs in Australia - see acsw.com.au.
   Alito also disagreed with the concurrence opinion that a detection dog was analogous to a thermal imaging device as per the "Kyllo v. United States" ruling. First, he argued that there should be no reasonable expectation of privacy if odors coming from the inside reach outside to areas where people may lawfully stand. Secondly, unlike a thermal imaging device, he stated that a dog, "is not a new form of 'technology' or a 'device'. And, as noted, the use of dogs' acute sense of smell in law enforcement dates back many centuries." Alito also noted that in the "Kyllo" case, police officers operated their thermal imaging device while on a public street, and if that same standard were applied to a dog, he feared that it would not be able to be used to detect, for example, "explosives, or for a violent fugitive or kidnapped child," outside from a public sidewalk as well.
   While the human brain is dominated by a large visual cortex, the dog brain is dominated by a large olfactory cortex. Dogs have roughly forty times more smell-sensitive receptors than humans, ranging from about 125 million to nearly 300 million in some dog breeds, such as bloodhounds. This is thought to make its sense of smell up to 40 times more sensitive than human's. These receptors are spread over an area about the size of a pocket handkerchief (compared to 5 million over an area the size of a postage stamp for humans). Dogs' sense of smell also includes the use of the vomeronasal organ, which is used primarily for social interactions.
   At CEATEC 2016, Aromajoin unveiled the first wearable scent device, Aroma Shooter Mini, which can be connected and controlled from PCs and smartphones. Besides, the company also introduced a demo scent-enabled chatting app named AromaMessage in the event.
  
  Section::::Current challenges.
  
  Current obstacles of mainstream adoption include the timing and distribution of scents, a fundamental understanding of human olfactory perception, the health dangers of synthetic odours, and other hurdles.
  
  Section::::See also.
  
  BULLET::::- Machine olfaction
  
  BULLET::::- Scentography
  
  Section::::External links.
  
  BULLET::::- DigiScents - A Revolution of the Senses archived on the Internet Archive (June 1, 2001)
   A brigade commander said that sniffer dogs are the most reliable way of detecting IEDs. However, statistical evidence gathered by the US Army Maneuver Support Center at Fort Leonard Wood, MO shows that the dogs are not the most effective means of detecting IEDs. The U.S. Army's 10th Mountain Division was the first unit to introduce explosive detection dogs in southern Afghanistan. In less than two years the dogs discovered 15 tons of illegal munitions, IED's, and weapons.
   Smell-O-Vision did not work as intended. According to a "Variety" review of the mystery comedy film "Scent of Mystery" (1960), which featured the one and only use of Smell-O-Vision, aromas were released with a distracting hissing noise and audience members in the balcony complained that the scents reached them several seconds after the action was shown on the screen. In other parts of the theater, the odors were too faint, causing audience members to sniff loudly in an attempt to catch the scent. These technical problems were mostly corrected after the first few showings, but the poor word of mouth, in conjunction with generally negative reviews of the film itself, led to the decline of Smell-O-Vision.
   Scientist Alexander Graham Bell popularized the notion that it was difficult to measure a smell, and in 1914 said the following:
  
  In the decades since Bell made this observation, no such science of odor materialised, and it was not until the 1950s and beyond that any real progress was made.
  
  Section::::Working principle.
  
  The electronic nose was developed in order to mimic human olfaction that functions as a non-separative mechanism: i.e. an odor / flavor is perceived as a global fingerprint.
   Section::::Development.
  
  In 2013, a group of researchers from the Tokyo University of Agriculture and Technology unveiled a prototype smelling screen to the public at the ACM/IEEE Virtual Reality Conference. The prototype device was only capable of dispensing one smell at a time. In the future, the researchers hope to use a cartridge system to create a variety of smells on demand.
  
  Section::::Applications.
  
  The inventors of the smelling screen suggest that it could be used to enhance advertising displays and museum exhibits. The product is in the early stages of development with no plans for commercial distribution in the near future.
   The interior building search takes place on the inside of any building. Some searches are only one room, some searches can contain multiple rooms. There is often an option for the search to be done on or off-leash.
  
  Exteriors 
  
  Exterior area search takes place outside, often it contains grass, dirt, cement and/or gravel. These searches can be especially difficult for the dogs as there are a number of new smells (trash/food, animals, etc.) the dogs are working in all weather conditions and the dogs may be tempted to mark or eliminate.
  
  Vehicles
   BULLET::::- The Brain Mapping Foundation used the electronic nose to detect brain cancer cells.
  
  Section::::Applications.:Possible and future applications in the field of crime prevention and security.
  
  BULLET::::- The ability of the electronic nose to detect odorless chemicals makes it ideal for use in the police force, such as the ability to detect drug odors despite other airborne odors capable of confusing police dogs. However this is unlikely in the near term as the cost of the electronic nose is quite high.
   Police require reasonable suspicion they will recover evidence in order to use a dog to sniff a person or their possessions in public. This is because using a dog to detect scents is considered a search. The main exemption to that rule are the dogs of the Canada Border Services Agency who are allowed to make searches without warrants under s.98 of the Customs Act.
   Electronic noses are able to discriminate between odors and volatiles from a wide range of sources. The list below shows just some of the typical applications for electronic nose technology – many are backed by research studies and published technical papers.
  
  Section::::Odor localization.
  
  Odor localization is a combination of quantitative chemical odor analysis and path-searching algorithms, and environmental conditions play a vital role in localization quality. Different methods are being researched for various purposes and in different real-world conditions.
  
  Section::::Odor localization.:Motivation.
  
presuppositions: Technology is more reliable than dogs for smelling. Dogs are not as reliable as technology for smelling.
corrections: While robot/machine noses do exist, but they tend to be good for limited applications, and can get "confused" easily; well trained dogs are very reliable for picking up odors. Robot/machine noses exist, but they tend to be good for limited applications compared to dogs.
raw_presuppositions: Technology is more reliable than dogs for smelling. Dogs are not as reliable as technology for smelling.
raw_corrections: While robot/machine noses do exist, but they tend to be good for limited applications, and can get "confused" easily; well trained dogs are very reliable for picking up odors. Robot/machine noses exist, but they tend to be good for limited applications compared to dogs.