Photorealism -- a Primer

Photorealism is a genre of art that encompasses painting, drawing and other graphic media, in which an artist studies a photograph and then attempts to reproduce the image as realistically as possible in another medium. Although the term can be used broadly to describe artworks in many different media, it is also used to refer specifically to a group of paintings and painters of the United States art movement that began in the late 1960s and early 1970s.

Origins

As a full-fledged art movement, Photorealism evolved from Pop Art and as a counter to Abstract Expressionism as well as Minimalist art movements in the late 1960s and early 1970s in the United States.  Photorealists use a photograph or several photographs to gather the information to create their paintings and it can be argued that the use of a camera and photographs is an acceptance of Modernism.  However, the admittance to the use of photographs in Photorealism was met with intense criticism when the movement began to gain momentum in the late 1960s, despite the fact that visual devices had been used since the fifteenth century to aid artists with their work.

The invention of photography in the nineteenth century had three effects on art: portrait and scenic artists were deemed inferior to the photograph and many turned to photography as careers; within nineteenth- and twentieth-century art movements it is well documented that artists used the photograph as source material and as an aid—however, they went to great lengths to deny the fact fearing that their work would be misunderstood as imitations; and through the photograph's invention artists were open to a great deal of new experimentation. Thus, the culmination of the invention of the photograph was a break in art's history towards the challenge facing the artist - since the earliest known cave drawings - trying to replicate the scenes they viewed.

By the time the Photorealists began producing their bodies of work the photograph had become the leading means of reproducing reality and abstraction was the focus of the art world.  Realism continued as an ongoing art movement, even experiencing a reemergence in the 1930s, but by the 1950s modernist critics and Abstract Expressionism had minimalized realism as a serious art undertaking.  Though Photorealists share some aspects of American realists, such as Edward Hopper, they tried to set themselves as much apart from traditional realists as they did Abstract Expressionists.  Photorealists were much more influenced by the work of Pop artists and were reacting against Abstract Expressionism.

                                                       Telephone Booths, Richard Estes,
                                                        oil on canvas, 1968

Pop Art and Photorealism were both reactionary movements stemming from the ever increasing and overwhelming abundance of photographic media, which by the mid 20th century had grown into such a massive phenomenon that it was threatening to lessen the value of imagery in art.  However, whereas the Pop artists were primarily pointing out the absurdity of much of the imagery (especially in commercial usage), the Photorealists were trying to reclaim and exalt the value of an image.

The association of Photorealism to Trompe L'oeil is a wrongly attributed comparison, an error in observation or interpretation made by many critics of the 1970s and 1980s. Trompe L'oeil paintings attempt to "fool the eye" and make the viewer think he is seeing an actual object, not a painted one. When observing a Photorealist painting, the viewer is always aware that they are looking at a painting.

Definition

The word Photorealism was coined by Louis K. Meisel in 1969 and appeared in print for the first time in 1970 in a Whitney Museum catalogue for the show "Twenty-two Realists."  It is also sometimes labeled as Super-Realism, New Realism, Sharp Focus Realism, or Hyper-Realism.

Louis K. Meisel, two years later, developed a five-point definition at the request of Stuart M. Speiser, who had commissioned a large collection of works by the Photorealists, which later developed into a traveling show known as 'Photo-Realism 1973: The Stuart M. Speiser Collection', which was donated to the Smithsonian in 1978 and is shown in several of its museums as well as traveling under the auspices of SITE.  The definition for the ORIGINATORS was as follows:

1. The Photo-Realist uses the camera and photograph to gather information.
2. The Photo-Realist uses a mechanical or semimechanical means to transfer the information to the canvas.
3. The Photo-Realist must have the technical ability to make the finished work appear photographic.
4. The artist must have exhibited work as a Photo-Realist by 1972 to be considered one of the central Photo-Realists.
5. The artist must have devoted at least five years to the development and exhibition of Photo-Realist work.

Artists

The first generation of American photorealists includes such painters as John Baeder, Richard Estes, Ralph Goings, Chuck Close, Charles Bell, Audrey Flack, Don Eddy, Robert Bechtle, and Tom Blackwell.  Often working independently of each other and with widely different starting points, these original photorealists routinely tackled mundane or familiar subjects in traditional art genres--landscapes (mostly urban rather than naturalistic), portraits, and still lifes.  In the UK, photorealist approaches were favoured by many artists including Mike Gorman and Eric Scott. The introduction of these European painters to a wider US audience was brought about through the 1982 'Superhumanism' exhibition at the Arnold Katzen Gallery, New York.

Though the movement is primarily associated with painting, Duane Hanson and John DeAndrea are sculptors associated with photorealism for their painted, lifelike sculptures of average people that were complete with simulated hair and real clothes. They are called Verists.

https://en.wikipedia.org/wiki/Photorealism

Day of the Dead

Day of the Dead (Spanish: Día de Muertos) is a Mexican holiday celebrated throughout Mexico, in particular the Central and South regions, and acknowledged around the world in other cultures. The holiday focuses on gatherings of family and friends to pray for and remember friends and family members who have died, and help support their spiritual journey. In 2008 the tradition was inscribed in the Representative List of the Intangible Cultural Heritage of Humanity by UNESCO.

The holiday is sometimes called Día de los Muertos in Anglophone countries, a back-translation of its original name, Día de Muertos. It is particularly celebrated in Mexico where the day is a public holiday. Prior to Spanish colonization in the 16th century, the celebration took place at the beginning of summer. It was moved to October 31, November 1 and November 2 to coincide with the Western Christian triduum of Allhallowtide: All Saints' Eve, All Saints' Day, and All Souls' Day. Traditions connected with the holiday include building private altars called ofrendas, honoring the deceased using sugar skulls, marigolds, and the favorite foods and beverages of the departed, and visiting graves with these as gifts. Visitors also leave possessions of the deceased at the graves.

                                                      Two Representations of "Catrina"

Scholars trace the origins of the modern Mexican holiday to indigenous observances dating back hundreds of years and to an Aztec festival dedicated to the goddess Mictecacihuatl. The holiday has spread throughout the world, being absorbed within other deep traditions for honoring the dead. It happens to be a holiday that has become a national symbol and as such is taught (for educational purposes) in the nation's schools, but there are families who are more inclined to celebrate a traditional "All Saints Day" associated with the Catholic Church.

Originally, the Day of the Dead as such was not celebrated in northern Mexico, where it was even unknown until the 20th century; before that the people and the church rejected it in northeastern Mexico because they perceived the day was a result of syncretizing pagan elements with Catholic Christianity. They held the traditional 'All Saints Day' in the same way as other Christians in the world. This is due to the limited or nonexistent Mesoamerican influence in this region, and the relatively few indigenous inhabitants from the regions of Southern Mexico. In the early 21st century in northern Mexico, Día de Muertos is observed because the Mexican government made it a national holiday by its educational policies from the 1960s and has tried to use it as a unifying national tradition in the north of the country.

In Brazil, Dia de Finados is a public holiday that many Brazilians celebrate by visiting cemeteries and churches. In Spain, festivals and parades are frequently held and people often gather at cemeteries and pray for their deceased loved ones at the end of the day. Similar observances occur elsewhere in Europe, and similarly themed celebrations appear in many Asian and African cultures.

In France and some other European countries, All Souls Day was observed by visits of families to the graves of loved ones, where they left chrysanthemums. Writer Marguerite Yourcenar observed that

"autumnal rites are among the oldest celebrated on earth. It appears that in every country the Day of the Dead occurs at the year's end, after the last harvests, when the barren earth is thought to give passage to the souls lying beneath it."

She also notes exceptions to the autumn season, such as the Buddhist Bon festival which is held in summer. But similarly themed celebrations of honoring the dead have been practiced since prehistoric times in many Asian and African cultures.

Origins

The Day of the Dead celebrations in Mexico developed from ancient traditions among its pre-Columbian cultures. Rituals celebrating the deaths of ancestors had been observed by these civilizations perhaps for as long as 2,500–3,000 years. The festival that developed into the modern Day of the Dead fell in the ninth month of the Aztec calendar, about the beginning of August, and was celebrated for an entire month. The festivities were dedicated to the goddess known as the "Lady of the Dead", corresponding to the modern La Calavera Catrina.

By the late 20th century in most regions of Mexico, the practices had developed to honor dead children and infants on November 1, and to honor deceased adults on November 2. November 1 is generally referred to as Día de los Inocentes ("Day of the Innocents") but also as Día de los Angelitos ("Day of the Little Angels"); November 2 is referred to as Día de los Muertos or Día de los Difuntos ("Day of the Dead").

https://en.wikipedia.org/wiki/Day_of_the_Dead

Safer Infant Formula

Bacteriophage Treatment
Decontaminates Infant Formula

American Society for Microbiology, Washington, DC -– October 23, 2015 -- A phage showed strong anti-microbial activity against a type of food-borne bacterium that often kills infants after infecting them via infant formula. Phages are viruses that infect only bacteria. The research is published October 23 online in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.

 In the study, the phage, called “CR5,” showed high antimicrobial activity against the bacterium, Cronobacter sakazakii, as well as against several other species of Cronobacter, which can also cause dangerous illness, said coauthor Sangryeol Ryu, professor in the Department of Agricultural Biotechnology, Research Institute of Agriculture and Life Sciences, Seoul National University, Korea.

 The research was conducted using infant formula that had been contaminated with C. sakazakii. “Interestingly, CR5 killed C. sakazakii quickly, and no C. sakazakii was detected in the infant formula after 10 hours had passed,” said Ryu.

 Ryu said that the phage is safe for humans, noting that his analysis of its genome revealed neither toxin gene nor virulence factor. In 2006, the US Food and Drug Administration approved the use of bacteriophages as biocontrol agents in foods. But the agency does not allow the use of antibiotics in infant formula.

 Bacteriophages are abundant in the environment, which means they are ecologically friendly, said Ryu. “They infect and kill only bacteria, which means they could be used as novel biocontrol agents and even as natural food preservatives,” he added, noting that other food-borne pathogens could also be controlled, by other types of phages.

Cronobacter, the target bacterial genus of the phage, CR5, is a family of closely related species that cause illness in people of all ages. While infection is rare in the US, these bacteria kill up to 40 percent of infected infants. Additionally, those that survive can face long-term neurological problems, according to the Centers for Disease Control and Prevention.

“Heretofore, C. sakazakii-contaminated infant formula has been considered an unsolved problem because antibiotics cannot be used,” said Ryu, adding that C. sakazakii has been known to have multiple antibiotic resistance genes. “In this study, we proved that C. sakazakii-phage CR5 is an efficient biocontrol agent in infant formula. Therefore, this bacteriophage treatment is a promising approach to solve this problem.”

https://www.asm.org/index.php/journal-press-releases/93831-bacteriophage-treatment-decontaminates-infant-formula

Superconductor Research

Caltech Physicists Uncover
Novel Phase of Matter
Finding could have implications for
high-temperature superconductivity
by Kimm Fesenmaier

CalTech – October 26, 2015 -- A team of physicists led by Caltech's David Hsieh has discovered an unusual form of matter—not a conventional metal, insulator, or magnet, for example, but something entirely different. This phase, characterized by an unusual ordering of electrons, offers possibilities for new electronic device functionalities and could hold the solution to a long-standing mystery in condensed matter physics having to do with high-temperature superconductivity—the ability for some materials to conduct electricity without resistance, even at "high" temperatures approaching  –100 degrees Celsius.

"The discovery of this phase was completely unexpected and not based on any prior theoretical prediction," says Hsieh, an assistant professor of physics, who previously was on a team that discovered another form of matter called a topological insulator. "The whole field of electronic materials is driven by the discovery of new phases, which provide the playgrounds in which to search for new macroscopic physical properties."

Hsieh and his colleagues describe their findings in the November issue of Nature Physics, and the paper is now available online. Liuyan Zhao, a postdoctoral scholar in Hsieh's group, is lead author on the paper.

The physicists made the discovery while testing a laser-based measurement technique that they recently developed to look for what is called multipolar order. To understand multipolar order, first consider a crystal with electrons moving around throughout its interior. Under certain conditions, it can be energetically favorable for these electrical charges to pile up in a regular, repeating fashion inside the crystal, forming what is called a charge-ordered phase. The building block of this type of order, namely charge, is simply a scalar quantity—that is, it can be described by just a numerical value, or magnitude.

In addition to charge, electrons also have a degree of freedom known as spin. When spins line up parallel to each other (in a crystal, for example), they form a ferromagnet—the type of magnet you might use on your refrigerator and that is used in the strip on your credit card. Because spin has both a magnitude and a direction, a spin-ordered phase is described by a vector.

Over the last several decades, physicists have developed sophisticated techniques to look for both of these types of phases. But what if the electrons in a material are not ordered in one of those ways? In other words, what if the order were described not by a scalar or vector but by something with more dimensionality, like a matrix? This could happen, for example, if the building block of the ordered phase was a pair of oppositely pointing spins—one pointing north and one pointing south—described by what is known as a magnetic quadrupole. Such examples of multipolar-ordered phases of matter are difficult to detect using traditional experimental probes.

As it turns out, the new phase that the Hsieh group identified is precisely this type of multipolar order.  

To detect multipolar order, Hsieh's group utilized an effect called optical harmonic generation, which is exhibited by all solids but is usually extremely weak. Typically, when you look at an object illuminated by a single frequency of light, all of the light that you see reflected from the object is at that frequency. When you shine a red laser pointer at a wall, for example, your eye detects red light. However, for all materials, there is a tiny amount of light bouncing off at integer multiples of the incoming frequency. So with the red laser pointer, there will also be some blue light bouncing off of the wall. You just do not see it because it is such a small percentage of the total light. These multiples are called optical harmonics.

The Hsieh group's experiment exploited the fact that changes in the symmetry of a crystal will affect the strength of each harmonic differently. Since the emergence of multipolar ordering changes the symmetry of the crystal in a very specific way—a way that can be largely invisible to conventional probes—their idea was that the optical harmonic response of a crystal could serve as a fingerprint of multipolar order.   

"We found that light reflected at the second harmonic frequency revealed a set of symmetries completely different from those of the known crystal structure, whereas this effect was completely absent for light reflected at the fundamental frequency," says Hsieh. "This is a very clear fingerprint of a specific type of multipolar order."

The specific compound that the researchers studied was strontium-iridium oxide (Sr₂IrO₄), a member of the class of synthetic compounds broadly known as iridates. Over the past few years, there has been a lot of interest in Sr₂IrO₄ owing to certain features it shares with copper-oxide-based compounds, or cuprates. Cuprates are the only family of materials known to exhibit superconductivity at high temperatures—exceeding 100 Kelvin (–173 degrees Celsius). Structurally, iridates and cuprates are very similar. And like the cuprates, iridates are electrically insulating antiferromagnets that become increasingly metallic as electrons are added to or removed from them through a process called chemical doping. A high enough level of doping will transform cuprates into high-temperature superconductors, and as cuprates evolve from being insulators to superconductors, they first transition through a mysterious phase known as the pseudogap, where an additional amount of energy is required to strip electrons out of the material. For decades, scientists have debated the origin of the pseudogap and its relationship to superconductivity—whether it is a necessary precursor to superconductivity or a competing phase with a distinct set of symmetry properties. If that relationship were better understood, scientists believe, it might be possible to develop materials that superconduct at temperatures approaching room temperature.

Recently, a pseudogap phase also has been observed in Sr₂IrO₄—and Hsieh's group has found that the multipolar order they have identified exists over a doping and temperature window where the pseudogap is present. The researchers are still investigating whether the two overlap exactly, but Hsieh says the work suggests a connection between multipolar order and pseudogap phenomena.

"There is also very recent work by other groups showing signatures of superconductivity in Sr₂IrO₄ of the same variety as that found in cuprates," he says. "Given the highly similar phenomenology of the iridates and cuprates, perhaps iridates will help us resolve some of the longstanding debates about the relationship between the pseudogap and high-temperature superconductivity."

Hsieh says the finding emphasizes the importance of developing new tools to try to uncover new phenomena. "This was really enabled by a simultaneous technique advancement," he says.

Furthermore, he adds, these multipolar orders might exist in many more materials. "Sr₂IrO₄ is the first thing we looked at, so these orders could very well be lurking in other materials as well, and that's exactly what we are pursuing next."

Additional Caltech authors on the paper, "Evidence of an odd-parity hidden order in a spin–orbit coupled correlated iridate," are Darius H. Torchinsky, Hao Chu, and Vsevolod Ivanov. Ron Lifshitz of Tel Aviv University, Rebecca Flint of Iowa State University, and Tongfei Qi and Gang Cao of the University of Kentucky are also coauthors. The work was supported by funding from the Army Research Office, the National Science Foundation (NSF), and the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center with support from the Gordon and Betty Moore Foundation.

http://www.caltech.edu/news/caltech-physicists-uncover-novel-phase-matter-48573

Fast Phosphor Light Switching

Researchers Transform Slow
Emitters into Fast Light Sources
By Kevin Stacey, Brown University

October 23, 2015 -- Phosphors are efficient light emitters but they’re not optimal for high-speed communications because they turn on and off slowly. Researchers from Brown and Harvard have now found a way to modulate light from phosphor emitters orders of magnitude faster using phase-change materials, which could make phosphors useful in a range of new optoelectronic applications.

Researchers from Brown University, in collaboration with colleagues from Harvard, have developed a new way to control light from phosphorescent emitters at very high speeds. The technique provides a new approach to modulation that could be useful in all kinds of silicon-based nanoscale devices, including computer chips and other optoelectronic components.

“Our results demonstrate relatively fast modulation from fundamentally slow phosphorescent light emitters,” said Rashid Zia, associate professor of engineering and physics at Brown and senior author of a new paper describing the work. “We think this could help make phosphors useful in a variety of new systems and settings.”

The paper is published today in Nature Communications.

Phosphors are common light emitters used in light bulbs, LEDs and elsewhere. They are extremely efficient because much of the energy pumped into them is converted to light as opposed to heat. But they have a slow optical lifetime, meaning it takes a relatively long time for them to return to the ground state after being excited. As a result, phosphors can’t be turned on and off very quickly. Glow-in-the-dark toys, for example, take advantage of this property.

That property is bad, however, for optical modulation, a process that often involves flipping the light on and off to encode information. Because of their slow lifetimes, phosphors have traditionally been a non-starter for applications that require high-speed modulation.

But in this latest work, Zia and collaborators, including researchers from Shriram Ramanathan’s group at Harvard University, took a different approach to modulation.

“Instead of changing how much light is coming out, which can only be done slowly in phosphor emitters, we came up with a system that changes another quality of that light, namely the color or spectrum of light emission, by rapidly changing the environment around the emitter,” Zia said.

The work was led by Sébastien Cueff, a postdoctoral researcher in Zia’s lab. Cueff started with an emitter made of erbium ions, an important phosphor that is widely used in fiber-optic telecommunication networks. He combined that with a material called vanadium dioxide (VO2). VO2 is a phase-change material that, when pumped with energy, changes very quickly from a transparent insulating state to a reflective metallic state. This change in reflectivity, in turn, switches how nearby erbium ions emit light. As the VO2 changes phase, the erbium emissions go from being generated mostly by magnetic dipole transitions (the rotational torque push and pull of magnetic forces), to being generated mostly by electric dipole transitions (the linear push and pull of electric forces). Those two emission pathways have distinct spectra, and the modulation back and forth between the two can be used as a means to encode information.

The researchers showed that this direct modulation of light emission could be done as quickly as the VO2 phase could be changed, which is much faster than the speed at which erbium can be turned on and off. The test system used in these initial experiments showed that the system could be switched three orders of magnitude faster than the optical lifetime of erbium.

“Phosphorescent emitters have been considered impractical for high speed applications because of their intrinsically long lifetimes,” Zia said. “Our results provide a simple way to circumvent this limitation and modulate their emission at high speeds.”

And that could enable the use of phosphors in new applications. One example could be optical communications networks on computer chips.

Prototype on-chip networks have used semiconductor lasers as light emitters. They can modulate very quickly, but they have downsides. Semiconductors can’t be grown directly on a silicon chip, so fabrication can be difficult. Using indirect means of modulation — interferometers, for example — makes for bulky systems that take up a lot of real estate on a chip. What’s more, semiconductor lasers are not particularly efficient. They produce a lot of heat along with light, which is a problem on a silicon chip.

Erbium and other phosphors, on the other hand, can be deposited directly on silicon, making fabrication easier. And phosphors are highly efficient, so heat is less of a concern. There’s still more work to be done to get such a system up to a speed that would be useful on a chip, but Zia and his colleagues think it’s possible.

In this initial experiment, the researchers used a laser to zap the VO2 and cause it to change phase. A faster means of changing the VO2 phase — perhaps using electricity instead of a laser — could make the system much faster still.

Zia and his group plan to continue to refine the technique, but they describe this first set of experiments as an important proof of concept. “We ... hope that the device and concept presented here will engage both academic and industrial researchers working on optoelectronics and nanophotonics,” the researchers write.

http://www.brown.edu/academics/engineering/news/2015-10/researchers-transform-slow-emitters-fast-light-sources

Satellite Finds Thousands of Comets

NASA -- Oct 25, 2015: For an astronomer, discovering a comet can be the highlight of a lifetime.  Great comets carry the names of their discoverers into history.  Comet Halley, Comet Lovejoy, Comet Hale-Bopp are just a few examples….

Imagine the frustration, though, if every time you discovered a comet, it was rapidly destroyed.

Believe it or not, this is what happens almost every day to the most prolific comet hunter of all time.

The Solar and Heliospheric Observatory, better known as “SOHO”, is a joint project of the European Space Agency, or ESA,  and NASA.  Orbiting the sun at 1.5 million km, or 932,000 miles from Earth, the distant observatory has just discovered its 3000^th comet—more than any other spacecraft or astronomer.  And, just about all of SOHO’s comets have been destroyed.

"They just disintegrate every time we observe one," said Karl Battams, a solar scientist at the Naval Research Labs in Washington, D.C., who has been in charge of running the SOHO comet-sighting website since 2003. “SOHO sees comets that pass very close to the sun—and they just can’t stand the intense sunlight.”

The overwhelming majority of SOHO's comet discoveries belong to the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet thousands of years ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. On average, a new member of the Kreutz family is discovered every three days. Unfortunately for these small comets, their orbits swoop perilously close to the sun.

"There's only one Kreutz comet that made it around the sun – Comet Lovejoy. And we are pretty confident it fell apart a couple of weeks afterwards," says Battams.

Although SOHO’s comets are rapidly destroyed, they nevertheless have great scientific value. For instance, the comets’ tails are buffeted and guided by the sun’s magnetic fields.  Watching how the tails bend and swing can tell researchers a great deal about the sun’s magnetic field.

Prior to the launch of SOHO in 1995, only a dozen or so comets had ever even been discovered from space, while some 900 had been discovered from the ground since 1761.  SOHO has turned the tables on these figures, making itself the greatest comet hunter of all time.

But SOHO hasn’t reached this lofty perch alone.   The spacecraft relies on people who sift through its data. Anyone can help because SOHO’s images are freely available online in real time.  Many volunteer amateur astronomers scan the data on a daily basis for signs of a new comet. The result: 95% of SOHO comets have been found by citizen scientists.

Whenever someone spots a comet, they report it to Battams. He goes over the imagery to confirm the sighting and then submits it to the Central Bureau for Astronomical Telegrams, which gives it an official name.

And the name is…you guessed it. “SOHO.”

While comets spotted from the ground are named after the person who first discovered them, comets first observed by a space-based telescope are named after the spacecraft.  The 3000^th comet discovered was named “SOHO-3000.”

Naturally, it has already been destroyed.  SOHO doesn’t mind though.  The Greatest Comet Hunter Ever has already moved on to the next sungrazer.

“SOHO-4000,” anyone?

Link (with video and simulation) at:

http://science.nasa.gov/science-news/science-at-nasa/2015/24oct_doomedcomets/

Fruit of the Poisonous Tree

Fruit of the poisonous tree is a legal metaphor in the United States used to describe evidence that is obtained illegally.  The logic of the terminology is that if the source (the "tree") of the evidence or evidence itself is tainted, then anything gained (the "fruit") from it is tainted as well. The fruit of the poisonous tree doctrine was first described in Silverthorne Lumber Co. v. United States, 251 U.S. 385 (1920).  The term's first use was by Justice Felix Frankfurter in Nardone v. United States (1939).

Such evidence is not generally admissible in court.  For example, if a police officer conducted an unconstitutional (Fourth Amendment) search of a home and obtained a key to a train station locker, and evidence of a crime came from the locker, that evidence would most likely be excluded under the fruit of the poisonous tree legal doctrine. The discovery of a witness is not evidence in itself because the witness is attenuated by separate interviews, in-court testimony and his or her own statements.

The doctrine is an extension of the exclusionary rule [see below], which, subject to some exceptions, prevents evidence obtained in violation of the Fourth Amendment from being admitted in a criminal trial. Like the exclusionary rule, the fruit of the poisonous tree doctrine is intended to deter police from using illegal means to obtain evidence.

The doctrine is subject to four main exceptions. The tainted evidence is admissible if:

1. it was discovered in part as a result of an independent, untainted source; or
2. it would inevitably have been discovered despite the tainted source; or
3. the chain of causation between the illegal action and the tainted evidence is too attenuated; or
4. the search warrant was not found to be valid based on probable cause, but was executed by government agents in good faith (called the good-faith exception).

This doctrine was also used by the European Court of Human Rights in Gäfgen v. Germany. In certain cases continental European countries have similar laws (e.g. in cases of torture), while the doctrine itself is generally not known. Illegally obtained evidence is used by the courts to ensure that the judgment is factually correct, however the person obtaining the illegal evidence typically faces independent consequences.

https://en.wikipedia.org/wiki/Fruit_of_the_poisonous_tree

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Exclusionary Rule

The exclusionary rule is a legal principle in the United States, under constitutional law, which holds that evidence collected or analyzed in violation of the defendant's constitutional rights is sometimes inadmissible for a criminal prosecution in a court of law. This may be considered an example of a prophylactic rule formulated by the judiciary in order to protect a constitutional right. The exclusionary rule may also, in some circumstances at least, be considered to follow directly from the constitutional language, such as the Fifth Amendment's command that no person "shall be compelled in any criminal case to be a witness against himself" and that no person "shall be deprived of life, liberty or property without due process of law".

"The exclusionary rule is grounded in the Fourth Amendment and it is intended to protect citizens from illegal searches and seizures."  The exclusionary rule is also designed to provide a remedy and disincentive, which is short of criminal prosecution in response to prosecutors and police who illegally gather evidence in violation of the Fifth Amendment in the Bill of Rights compelled to self-incrimination. The exclusionary rule also applies to violations of the Sixth Amendment, which guarantees the right to counsel.

Most states also have their own exclusionary remedies for illegally obtained evidence under their state constitutions and/or statutes, some of which predate the federal constitutional guarantees against unlawful searches and seizures and compelled self-incrimination.

This rule is occasionally referred to as a legal technicality because it allows defendants a defense that does not address whether the crime was actually committed. In this respect, it is similar to the explicit rule in the Fifth Amendment protecting people from double jeopardy. In strict cases, when an illegal action is used by police/prosecution to gain any incriminating result, all evidence whose recovery stemmed from the illegal action—this evidence is known as "fruit of the poisonous tree"—can be thrown out from a jury (or be grounds for a mistrial if too much information has been irrevocably revealed).

The exclusionary rule applies to all persons within the United States regardless of whether they are citizens, immigrants (legal or illegal), or visitors.

https://en.wikipedia.org/wiki/Exclusionary_rule