title: Heligoland

text: The climate of Heligoland is typical of an offshore climate, being almost free of pollen and thus ideal for people with pollen allergies. Since there is no land mass in the vicinity, temperatures rarely drop below even in the winter. At times, winter temperatures can be higher than in Hamburg by up to because cold winds from Russia are weakened. While spring tends to be comparatively cool, autumn on Heligoland is often longer and warmer than on the mainland, and statistically, the climate is generally sunnier. The coldest temperature ever recorded on Heligoland was in February 1956, while the highest was in July 1994.


title: Heligoland

text: Owing to the mild climate, figs have reportedly been grown on the island as early as 1911, and a 2005 article mentioned Japanese bananas, figs, agaves, palm trees and other exotic plants that had been planted on Heligoland and were thriving. There still is an old mulberry tree in the Upper Town.


title: Heligoland

text: The island of Heligoland is a geological oddity; the presence of the main island's characteristic red sedimentary rock in the middle of the German Bight is unusual. It is the only such formation of cliffs along the continental coast of the North Sea. The formation itself, called the Bunter sandstone or Buntsandstein, is from the early Triassic geologic age. It is older than the white chalk that underlies the island Düne, the same rock that forms the White Cliffs of Dover in England and cliffs of Danish and German islands in the Baltic Sea. A small chalk rock close to Heligoland, called "witt Kliff" (white cliff), is known to have existed within sight of the island to the west until the early 18th century, when storm floods finally eroded it to below sea level.


title: Heligoland

text: Heligoland's rock is significantly harder than the postglacial sediments and sands forming the islands and coastlines to the east of the island. This is why the core of the island, which a thousand years ago was still surrounded by a large, low-lying marshland and sand dunes separated from coast in the east only by narrow channels, has remained to this day, although the onset of the North Sea has long eroded away all of its surroundings. A small piece of Heligoland's sand dunes remains—the sand isle just across the harbour called Düne (Dune). A referendum in June 2011 dismissed a proposal to reconnect the main island to the Düne islet with a landfill.


title: Heligoland

text: The Heligoland flag is very similar to its coat of arms—it is a tricolour flag with three horizontal bars, from top to bottom: green, red and white. Each of the colours has its symbolic meaning, as expressed in its motto:


title: Heligoland

text: A special section in the German traffic regulations ("Straßenverkehrsordnung", abbr. "StVO"), §50, prohibits the use of automobiles and bicycles on the island. Kick scooters are sometimes used as substitutes for bicycles.


title: Heligoland

text: There are very few cars on Heligoland; except for the local ambulance van and the small firetrucks, the only motor vehicles on the island are electrically powered and used primarily for moving material. The island received its first police car on 17 January 2006; until then the island's policemen moved on foot and by bicycle, being exempt from the bicycle ban.


title: Heligoland

text: Ambulance services are provided by the Paracelsus North Sea Clinic Helgoland in cooperation with the State Rescue Service of Schleswig-Holstein (RKiSH). There are three ambulances available: one on the main island and one on Düne; the third is in reserve on the main island.


title: Heligoland

text: The ambulance service drives first to the Paracelsus North Sea Clinic. In the event of serious injuries or illnesses, the patients are transferred to the mainland with a rescue helicopter or a sea rescue cruiser operated by the German Society for the Rescue of Shipwrecked Persons (DGzRS).


title: Heligoland

text: If there is an emergency on the Düne, the ambulance crew takes a boat to the dune and carries out the operation with the ambulance based there.


title: Heligoland

text: Fire protection and technical assistance are provided by the Helgoland volunteer fire brigade, which has three stations (Unterland, Oberland and Düne).The tasks also include ensuring fire protection during flight operations at the Heligoland-Düne airfield. Volunteer firefighters are deployed on Düne in the summer, who report for 14 days and go on holiday with their families on the island and go into action in an emergency.


title: Heligoland

text: There are normally five police officers based on Heligoland. They have the use of an electric car and a number of bicycles. In the summer months the population can also triple with up to 3,000 daytrippers and additional overnight visitors. Occasionally the usual complement of police officers in supplemented by additional officers from the mainland during this period.


title: Heligoland

text: Since 2021, the so-called BOS center, a joint service building for the fire brigade, ambulance service and police, has been under construction on the Oberland, and will incorporate five apartments for police staff on the upper floor.


title: Global catastrophic risk

text: A global catastrophic risk or a doomsday scenario is a hypothetical future event that could damage human well-being on a global scale, even endangering or destroying modern civilization. An event that could cause human extinction or permanently and drastically curtail humanity's potential is known as an "existential risk."


title: Global catastrophic risk

text: Over the last two decades, a number of academic and non-profit organizations have been established to research global catastrophic and existential risks, formulate potential mitigation measures and either advocate for or implement these measures.


title: Global catastrophic risk

text: The term global catastrophic risk "lacks a sharp definition", and generally refers (loosely) to a risk that could inflict "serious damage to human well-being on a global scale".


title: Global catastrophic risk

text: Humanity has suffered large catastrophes before. Some of these have caused serious damage but were only local in scope—e.g. the Black Death may have resulted in the deaths of a third of Europe's population, 10% of the global population at the time. Some were global, but were not as severe—e.g. the 1918 influenza pandemic killed an estimated 3–6% of the world's population. Most global catastrophic risks would not be so intense as to kill the majority of life on earth, but even if one did, the ecosystem and humanity would eventually recover (in contrast to "existential risks").


title: Global catastrophic risk

text: Similarly, in "", Richard Posner singles out and groups together events that bring about "utter overthrow or ruin" on a global, rather than a "local or regional", scale. Posner highlights such events as worthy of special attention on cost–benefit grounds because they could directly or indirectly jeopardize the survival of the human race as a whole.


title: Global catastrophic risk

text: Existential risks are defined as "risks that threaten the destruction of humanity's long-term potential." The instantiation of an existential risk (an "existential catastrophe") would either cause outright human extinction or irreversibly lock in a drastically inferior state of affairs. Existential risks are a sub-class of global catastrophic risks, where the damage is not only "global" but also "terminal" and "permanent," preventing recovery and thereby affecting both current and all future generations.


title: Global catastrophic risk

text: While extinction is the most obvious way in which humanity's long-term potential could be destroyed, there are others, including "unrecoverable" "collapse" and "unrecoverable" "dystopia". A disaster severe enough to cause the permanent, irreversible collapse of human civilisation would constitute an existential catastrophe, even if it fell short of extinction. Similarly, if humanity fell under a totalitarian regime, and there were no chance of recovery then such a dystopia would also be an existential catastrophe. Bryan Caplan writes that "perhaps an eternity of totalitarianism would be worse than extinction". (George Orwell's novel "Nineteen Eighty-Four" suggests an example.) A dystopian scenario shares the key features of extinction and unrecoverable collapse of civilisation—before the catastrophe, humanity faced a vast range of bright futures to choose from; after the catastrophe, humanity is locked forever in a terrible state.


title: Global catastrophic risk

text: Potential global catastrophic risks are conventionally classified as anthropogenic or non-anthropogenic hazards.  Examples of non-anthropogenic risks are an asteroid impact event, a supervolcanic eruption, a lethal gamma-ray burst, a geomagnetic storm destroying electronic equipment, natural long-term climate change, hostile extraterrestrial life, or the predictable Sun transforming into a red giant star engulfing the Earth.


title: Global catastrophic risk

text: Anthropogenic risks are those caused by humans and include those related to technology, governance, and climate change. Technological risks include the creation of artificial intelligence misaligned with human goals, biotechnology, and nanotechnology. Insufficient or malign global governance creates risks in the social and political domain, such as global war and nuclear holocaust, bioterrorism using genetically modified organisms, cyberterrorism destroying critical infrastructure like the electrical grid, or the failure to manage a natural or engineered pandemic. Global catastrophic risks in the domain of earth system governance include global warming, environmental degradation, extinction of species, famine as a result of non-equitable resource distribution, human overpopulation, crop failures, and non-sustainable agriculture.


title: Global catastrophic risk

text: Research into the nature and mitigation of global catastrophic risks and existential risks is subject to a unique set of challenges and, as a result, is not easily subjected to the usual standards of scientific rigour. For instance, it is neither feasible nor ethical to study these risks experimentally. Carl Sagan expressed this with regards to nuclear war: "Understanding the long-term consequences of nuclear war is not a problem amenable to experimental verification". Moreover, many catastrophic risks change rapidly as technology advances and background conditions, such as geopolitical conditions, change. Another challenge is the general difficulty of accurately predicting the future over long timescales, especially for anthropogenic risks which depend on complex human political, economic and social systems. In addition to known and tangible risks, unforeseeable black swan extinction events may occur, presenting an additional methodological problem.


title: Global catastrophic risk

text: Humanity has never suffered an existential catastrophe and if one were to occur, it would necessarily be unprecedented. Therefore, existential risks pose unique challenges to prediction, even more than other long-term events, because of observation selection effects. Unlike with most events, the failure of a complete extinction event to occur in the past is not evidence against their likelihood in the future, because every world that has experienced such an extinction event has no observers, so regardless of their frequency, no civilization observes existential risks in its history. These anthropic issues may partly be avoided by looking at evidence that does not have such selection effects, such as asteroid impact craters on the Moon, or directly evaluating the likely impact of new technology.


title: Global catastrophic risk

text: To understand the dynamics of an unprecedented, unrecoverable global civilizational collapse (a type of existential risk), it may be instructive to study the various local civilizational collapses that have occurred throughout human history. For instance, civilizations such as the Roman Empire have ended in a loss of centralized governance and a major civilization-wide loss of infrastructure and advanced technology. However, these examples demonstrate that societies appear to be fairly resilient to catastrophe; for example, Medieval Europe survived the Black Death without suffering anything resembling a civilization collapse despite losing 25 to 50 percent of its population.


title: Global catastrophic risk

text: There are economic reasons that can explain why so little effort is going into existential risk reduction. It is a global public good, so we should expect it to be undersupplied by markets. Even if a large nation invests in risk mitigation measures, that nation will enjoy only a small fraction of the benefit of doing so. Furthermore, existential risk reduction is an "intergenerational" global public good, since most of the benefits of existential risk reduction would be enjoyed by future generations, and though these future people would in theory perhaps be willing to pay substantial sums for existential risk reduction, no mechanism for such a transaction exists.


title: Global catastrophic risk

text: Numerous cognitive biases can influence people's judgment of the importance of existential risks, including scope insensitivity, hyperbolic discounting, availability heuristic, the conjunction fallacy, the affect heuristic, and the overconfidence effect.


title: Global catastrophic risk

text: Scope insensitivity influences how bad people consider the extinction of the human race to be. For example, when people are motivated to donate money to altruistic causes, the quantity they are willing to give does not increase linearly with the magnitude of the issue: people are roughly as willing to prevent the deaths of 200,000 or 2,000 birds. Similarly, people are often more concerned about threats to individuals than to larger groups.


title: Global catastrophic risk

text: Eliezer Yudkowsky theorizes that scope neglect plays a role in public perception of existential risks:


title: Global catastrophic risk

text: Substantially larger numbers, such as 500 million deaths, and especially qualitatively different scenarios such as the extinction of the entire human species, seem to trigger a different mode of thinking... People who would never dream of hurting a child hear of existential risk, and say, "Well, maybe the human species doesn't really deserve to survive".


title: Global catastrophic risk

text: All past predictions of human extinction have proven to be false. To some, this makes future warnings seem less credible. Nick Bostrom argues that the absence of human extinction in the past is weak evidence that there will be no human extinction in the future, due to survivor bias and other anthropic effects.


title: Global catastrophic risk

text: Sociobiologist E. O. Wilson argued that: "The reason for this myopic fog, evolutionary biologists contend, is that it was actually advantageous during all but the last few millennia of the two million years of existence of the genus Homo... A premium was placed on close attention to the near future and early reproduction, and little else. Disasters of a magnitude that occur only once every few centuries were forgotten or transmuted into myth."


title: Global catastrophic risk

text: Defense in depth is a useful framework for categorizing risk mitigation measures into three layers of defense:


title: Global catastrophic risk

text: Human extinction is most likely when all three defenses are weak, that is, "by risks we are unlikely to prevent, unlikely to successfully respond to, and unlikely to be resilient against".


title: Global catastrophic risk

text: The unprecedented nature of existential risks poses a special challenge in designing risk mitigation measures since humanity will not be able to learn from a track record of previous events.


title: Global catastrophic risk

text: Some researchers argue that both research and other initiatives relating to existential risk are underfunded. Nick Bostrom states that more research has been done on "Star Trek", snowboarding, or dung beetles than on existential risks. Bostrom's comparisons have been criticized as "high-handed". As of 2020, the Biological Weapons Convention organization had an annual budget of US$1.4 million.


title: Global catastrophic risk

text: Some scholars propose the establishment on Earth of one or more self-sufficient, remote, permanently occupied settlements specifically created for the purpose of surviving a global disaster. Economist Robin Hanson argues that a refuge permanently housing as few as 100 people would significantly improve the chances of human survival during a range of global catastrophes.


title: Global catastrophic risk

text: Food storage has been proposed globally, but the monetary cost would be high. Furthermore, it would likely contribute to the current millions of deaths per year due to malnutrition. In 2022, a team led by David Denkenberger modeled the cost-effectiveness of resilient foods to artificial general intelligence (AGI) safety and found "∼98-99% confidence" for a higher marginal impact of work on resilient foods. Some survivalists stock survival retreats with multiple-year food supplies.


title: Global catastrophic risk

text: The Svalbard Global Seed Vault is buried inside a mountain on an island in the Arctic. It is designed to hold 2.5 billion seeds from more than 100 countries as a precaution to preserve the world's crops. The surrounding rock is (as of 2015) but the vault is kept at by refrigerators powered by locally sourced coal.


title: Global catastrophic risk

text: More speculatively, if society continues to function and if the biosphere remains habitable, calorie needs for the present human population might in theory be met during an extended absence of sunlight, given sufficient advance planning. Conjectured solutions include growing mushrooms on the dead plant biomass left in the wake of the catastrophe, converting cellulose to sugar, or feeding natural gas to methane-digesting bacteria.


title: Global catastrophic risk

text: Insufficient global governance creates risks in the social and political domain, but the governance mechanisms develop more slowly than technological and social change. There are concerns from governments, the private sector, as well as the general public about the lack of governance mechanisms to efficiently deal with risks, negotiate and adjudicate between diverse and conflicting interests. This is further underlined by an understanding of the interconnectedness of global systemic risks. In absence or anticipation of global governance, national governments can act individually to better understand, mitigate and prepare for global catastrophes.


title: Global catastrophic risk

text: In 2018, the Club of Rome called for greater climate change action and published its Climate Emergency Plan, which proposes ten action points to limit global average temperature increase to 1.5 degrees Celsius. Further, in 2019, the Club published the more comprehensive Planetary Emergency Plan.


title: Global catastrophic risk

text: There is evidence to suggest that collectively engaging with the emotional experiences that emerge during contemplating the vulnerability of the human species within the context of climate change allows for these experiences to be adaptive. When collective engaging with and processing emotional experiences is supportive, this can lead to growth in resilience, psychological flexibility, tolerance of emotional experiences, and community engagement.


title: Global catastrophic risk

text: Space colonization is a proposed alternative to improve the odds of surviving an extinction scenario. Solutions of this scope may require megascale engineering.


title: Global catastrophic risk

text: Astrophysicist Stephen Hawking advocated colonizing other planets within the solar system once technology progresses sufficiently, in order to improve the chance of human survival from planet-wide events such as global thermonuclear war.


title: Global catastrophic risk

text: Billionaire Elon Musk writes that humanity must become a multiplanetary species in order to avoid extinction. Musk is using his company SpaceX to develop technology he hopes will be used in the colonization of Mars.


title: Global catastrophic risk

text: In a few billion years, the Sun will expand into a red giant, swallowing the Earth. This can be avoided by moving the Earth farther out from the Sun, keeping the temperature roughly constant. That can be accomplished by tweaking the orbits of comets and asteroids so they pass close to the Earth in such a way that they add energy to the Earth's orbit. Since the Sun's expansion is slow, roughly one such encounter every 6,000 years would suffice.


title: Global catastrophic risk

text: Psychologist Steven Pinker has called existential risk a "useless category" that can distract from real threats such as climate change and nuclear war.


title: Global catastrophic risk

text: The Bulletin of the Atomic Scientists (est. 1945) is one of the oldest global risk organizations, founded after the public became alarmed by the potential of atomic warfare in the aftermath of WWII. It studies risks associated with nuclear war and energy and famously maintains the Doomsday Clock established in 1947. The Foresight Institute (est. 1986) examines the risks of nanotechnology and its benefits. It was one of the earliest organizations to study the unintended consequences of otherwise harmless technology gone haywire at a global scale. It was founded by K. Eric Drexler who postulated "grey goo".


title: Global catastrophic risk

text: Beginning after 2000, a growing number of scientists, philosophers and tech billionaires created organizations devoted to studying global risks both inside and outside of academia.


title: Global catastrophic risk

text: Independent non-governmental organizations (NGOs) include the Machine Intelligence Research Institute (est. 2000), which aims to reduce the risk of a catastrophe caused by artificial intelligence, with donors including Peter Thiel and Jed McCaleb. The Nuclear Threat Initiative (est. 2001) seeks to reduce global threats from nuclear, biological and chemical threats, and containment of damage after an event. It maintains a nuclear material security index. The Lifeboat Foundation (est. 2009) funds research into preventing a technological catastrophe. Most of the research money funds projects at universities. The Global Catastrophic Risk Institute (est. 2011) is a US-based non-profit, non-partisan think tank founded by Seth Baum and Tony Barrett. GCRI does research and policy work across various risks, including artificial intelligence, nuclear war, climate change, and asteroid impacts. The Global Challenges Foundation (est. 2012), based in Stockholm and founded by Laszlo Szombatfalvy, releases a yearly report on the state of global risks. The Future of Life Institute (est. 2014) works to reduce extreme, large-scale risks from transformative technologies, as well as steer the development and use of these technologies to benefit all life, through grantmaking, policy advocacy in the United States, European Union and United Nations, and educational outreach. Elon Musk, Vitalik Buterin and Jaan Tallinn are some of its biggest donors. The Center on Long-Term Risk (est. 2016), formerly known as the Foundational Research Institute, is a British organization focused on reducing risks of astronomical suffering (s-risks) from emerging technologies.


title: Global catastrophic risk

text: University-based organizations include the Future of Humanity Institute (est. 2005) which researches the questions of humanity's long-term future, particularly existential risk. It was founded by Nick Bostrom and is based at Oxford University. The Centre for the Study of Existential Risk (est. 2012) is a Cambridge University-based organization which studies four major technological risks: artificial intelligence, biotechnology, global warming and warfare. All are man-made risks, as Huw Price explained to the AFP news agency, "It seems a reasonable prediction that some time in this or the next century intelligence will escape from the constraints of biology". He added that when this happens "we're no longer the smartest things around," and will risk being at the mercy of "machines that are not malicious, but machines whose interests don't include us." Stephen Hawking was an acting adviser. The Millennium Alliance for Humanity and the Biosphere is a Stanford University-based organization focusing on many issues related to global catastrophe by bringing together members of academia in the humanities. It was founded by Paul Ehrlich, among others. Stanford University also has the Center for International Security and Cooperation focusing on political cooperation to reduce global catastrophic risk. The Center for Security and Emerging Technology was established in January 2019 at Georgetown's Walsh School of Foreign Service and will focus on policy research of emerging technologies with an initial emphasis on artificial intelligence. They received a grant of 55M USD from Good Ventures as suggested by Open Philanthropy.


title: Global catastrophic risk

text: Other risk assessment groups are based in or are part of governmental organizations. The World Health Organization (WHO) includes a division called the Global Alert and Response (GAR) which monitors and responds to global epidemic crisis. GAR helps member states with training and coordination of response to epidemics. The United States Agency for International Development (USAID) has its Emerging Pandemic Threats Program which aims to prevent and contain naturally generated pandemics at their source. The Lawrence Livermore National Laboratory has a division called the Global Security Principal Directorate which researches on behalf of the government issues such as bio-security and counter-terrorism.


title: Dante Gabriel Rossetti

text: Gabriel Charles Dante Rossetti (12 May 1828 – 9 April 1882), generally known as Dante Gabriel Rossetti (), was an English poet, illustrator, painter, translator and member of the Rossetti family. He founded the Pre-Raphaelite Brotherhood in 1848 with William Holman Hunt and John Everett Millais. Rossetti inspired the next generation of artists and writers, William Morris and Edward Burne-Jones in particular. His work also influenced the European Symbolists and was a major precursor of the Aesthetic movement.


title: Dante Gabriel Rossetti

text: Rossetti's art was characterised by its sensuality and its medieval revivalism. His early poetry was influenced by John Keats and William Blake. His later poetry was characterised by the complex interlinking of thought and feeling, especially in his sonnet sequence, "The House of Life". Poetry and image are closely entwined in Rossetti's work. He frequently wrote sonnets to accompany his pictures, spanning from "The Girlhood of Mary Virgin" (1849) and "Astarte Syriaca" (1877), while also creating art to illustrate poems such as "Goblin Market" by the celebrated poet Christina Rossetti, his sister.


title: Dante Gabriel Rossetti

text: Rossetti's personal life was closely linked to his work, especially his relationships with his models and muses Elizabeth Siddal (whom he married), Fanny Cornforth and Jane Morris.


title: Dante Gabriel Rossetti

text: The son of émigré Italian scholar Gabriele Pasquale Giuseppe Rossetti and his wife Frances Mary Lavinia Polidori, Gabriel Charles Dante Rossetti was born in London, on 12 May 1828. His family and friends called him Gabriel, but in publications he put the name Dante first in honour of Dante Alighieri. He was the brother of poet Christina Rossetti, critic William Michael Rossetti, and author Maria Francesca Rossetti. His father was a Roman Catholic, at least prior to his marriage, and his mother was an Anglican; ostensibly Gabriel was baptised as and was a practising Anglican. John William Polidori, who had died seven years before his birth, was Rossetti's maternal uncle. During his childhood, Rossetti was home educated and later attended King's College School, and often read the Bible, along with the works of Shakespeare, Dickens, Sir Walter Scott, and Lord Byron.


title: Dante Gabriel Rossetti

text: The youthful Rossetti is described as "self-possessed, articulate, passionate and charismatic" but also "ardent, poetic and feckless". Like all his siblings, he aspired to be a poet and attended King's College School, in its original location near the Strand in London. He also wished to be a painter, having shown a great interest in Medieval Italian art. He studied at Henry Sass' Drawing Academy from 1841 to 1845, when he enrolled in the Antique School of the Royal Academy, which he left in 1848. After leaving the Royal Academy, Rossetti studied under Ford Madox Brown, with whom he retained a close relationship throughout his life.


title: Dante Gabriel Rossetti

text: Following the exhibition of William Holman Hunt's painting "The Eve of St. Agnes", Rossetti sought out Hunt's friendship. The painting illustrated a poem by John Keats. Rossetti's own poem, "The Blessed Damozel", was an imitation of Keats, and he believed Hunt might share his artistic and literary ideals. Together they developed the philosophy of the Pre-Raphaelite Brotherhood which they founded along with John Everett Millais.


title: Dante Gabriel Rossetti

text: The group's intention was to reform English art by rejecting what they considered to be the mechanistic approach first adopted by the Mannerist artists who succeeded Raphael and Michelangelo and the formal training regime introduced by Sir Joshua Reynolds. Their approach was to return to the abundant detail, intense colours, and complex compositions of Quattrocento Italian and Flemish art. The eminent critic John Ruskin wrote:


title: Dante Gabriel Rossetti

text: For the first issue of the brotherhood's magazine, "The Germ", published early in 1850, Rossetti contributed a poem, "The Blessed Damozel", and a story about a fictional early Italian artist inspired by a vision of a woman who bids him combine the human and the divine in his art. Rossetti was always more interested in the medieval than in the modern side of the movement, working on translations of Dante and other medieval Italian poets, and adopting the stylistic characteristics of the early Italians.


title: Dante Gabriel Rossetti

text: Rossetti's first major paintings in oil display the realist qualities of the early Pre-Raphaelite movement. His "Girlhood of Mary Virgin" (1849) and "Ecce Ancilla Domini" (1850) portray Mary as a teenage girl. William Bell Scott saw "Girlhood" in progress in Hunt's studio and remarked on young Rossetti's technique:


title: Dante Gabriel Rossetti

text: Stung by criticism of his second major painting, "Ecce Ancilla Domini", exhibited in 1850, and the "increasingly hysterical critical reaction that greeted Pre-Raphaelitism" that year, Rossetti turned to watercolours, which could be sold privately. Although his work subsequently won support from John Ruskin, Rossetti only rarely exhibited thereafter.


title: Dante Gabriel Rossetti

text: In 1850, Rossetti met Elizabeth Siddal, an important model for the Pre-Raphaelite painters. Over the next decade, she became his muse, his pupil, and his passion. They were married in 1860. Rossetti's incomplete picture "Found", begun in 1853 and unfinished at his death, was his only major modern-life subject. It depicted a prostitute, lifted from the street by a country drover who recognises his old sweetheart. However, Rossetti increasingly preferred symbolic and mythological images to realistic ones.


title: Dante Gabriel Rossetti

text: For many years, Rossetti worked on English translations of Italian poetry including Dante Alighieri's "La Vita Nuova" (published as "The Early Italian Poets" in 1861). These and Sir Thomas Malory's "Le Morte d'Arthur" inspired his art of the 1850s. He created a method of painting in watercolours, using thick pigments mixed with gum to give rich effects similar to medieval illuminations. He also developed a novel drawing technique in pen-and-ink. His first published illustration was "The Maids of Elfen-Mere" (1855), for a poem by his friend William Allingham, and he contributed two illustrations to Edward Moxon's 1857 edition of Alfred, Lord Tennyson's "Poems" and illustrations for works by his sister Christina Rossetti.


title: Dante Gabriel Rossetti

text: His visions of Arthurian romance and medieval design also inspired William Morris and Edward Burne-Jones. Neither Burne-Jones nor Morris knew Rossetti, but were much influenced by his works, and met him by recruiting him as a contributor to their "Oxford and Cambridge Magazine" which Morris founded in 1856 to promote his ideas about art and poetry.


title: Dante Gabriel Rossetti

text: That summer Morris and Rossetti visited Oxford and finding the Oxford Union debating-hall under construction, pursued a commission to paint the upper walls with scenes from "Le Morte d'Arthur" and to decorate the roof between the open timbers. Seven artists were recruited, among them Valentine Prinsep and Arthur Hughes, and the work was hastily begun. The frescoes, done too soon and too fast, began to fade at once and now are barely decipherable. Rossetti recruited two sisters, Bessie and Jane Burden, as models for the Oxford Union murals, and Jane became Morris's wife in 1859.


title: Dante Gabriel Rossetti

text: Literature was integrated into the Pre-Raphaelite Brotherhood's artistic practice from the beginning (including that of Rossetti), with many paintings making direct literary references. For example, John Everett Millais' early work, "Isabella" (1849), depicts an episode from John Keats' "Isabella, or, the Pot of Basil" (1818). Rossetti was particularly critical of the gaudy ornamentation of Victorian gift books and sought to refine bindings and illustrations to align with the principles of the Aesthetic Movement. Rossetti's key bindings were designed between 1861 and 1871. He collaborated as a designer/illustrator with his sister, poet Christina Rossetti, on the first edition of "Goblin Market" (1862) and "The Prince's Progress" (1866).


title: Dante Gabriel Rossetti

text: One of Rossetti's most prominent contributions to illustration was the collaborative book, "Poems" by Alfred, Lord Tennyson (published by Edward Moxon in 1857 and known colloquially as the 'Moxon Tennyson'). Moxon envisioned Royal Academicians as the illustrators for the ambitious project, but this vision was quickly disrupted once Millais, a founding member of the Pre-Raphaelite Brotherhood, became involved in the project. Millais recruited William Holman Hunt and Rossetti for the project, and the involvement of these artists reshaped the entire production of the book. In reference to the Pre-Raphaelite illustrations, Laurence Housman wrote "[...] The illustrations of the Pre-Raphaelites were personal and intellectual readings of the poems to which they belonged, not merely echoes in line of the words of the text." The Pre-Raphaelites’ visualization of Tennyson's poems indicated the range of possibilities in interpreting written works, as did their unique approach to visualizing narrative on the canvas.


title: Dante Gabriel Rossetti

text: Pre-Raphaelite illustrations do not simply refer to the text in which they appear; rather, they are part of a bigger program of art: the book as a whole. Rossetti's philosophy about the role of illustration was revealed in an 1855 letter to poet William Allingham, when he wrote, in reference to his work on the Moxon Tennyson:


title: Dante Gabriel Rossetti

text: "I have not begun even designing for them yet, but fancy I shall try the "Vision of Sin", and "Palace of Art" etc.—those where one can allegorize on one’s own hook, without killing for oneself and everyone a distinct idea of the poet’s."


title: Dante Gabriel Rossetti

text: This passage makes apparent Rossetti's desire not to just support the poet's narrative, but to create an allegorical illustration that functions separately from the text as well. In this respect, Pre-Raphaelite illustrations go beyond depicting an episode from a poem, but rather function like subject paintings within a text. Illustration is not subservient to text and vice versa. Careful and conscientious craftsmanship is practiced in every aspect of production, and each element, though qualifiedly artistic in its own right, contributes to a unified art object (the book).


title: Dante Gabriel Rossetti

text: England began to see a revival of religious beliefs and practices starting in 1833 and moving onward to about 1845. The Oxford Movement, also known as the Tractarian Movement, had recently begun a push toward the restoration of Christian traditions that had been lost in the Church of England. Rossetti and his family had been attending Christ Church, Albany Street since 1843. His brother, William Michael Rossetti recorded that services had begun changing in the church since the start of the "High Anglican movement". Rev. William Dodsworth was responsible for these changes, including the addition of the Catholic practice of placing flowers and candles by the altar. Rossetti and his family, along with two of his colleagues (one of which cofounded the Pre-Raphaelite Brotherhood) had also attended St. Andrew's on Wells Street, a High Anglican church. It is noted that the Anglo-Catholic revival very much affected Rossetti in the late 1840s and early 1850s. The spiritual expressions of his painting "The Girlhood of Mary Virgin," finished in 1849, are evident of this claim. The painting's altar is decorated very similarly to that of a Catholic altar, proving his familiarity with the Anglo-Catholic revival. The subject of the painting, the Blessed Virgin, is sewing a red cloth, a significant part of the Oxford Movement that emphasized the embroidering of altar cloths by women. Oxford Reformers identified two major aspects to their movement, that "the end of all religion must be communion with God," and "that the Church was divinely instituted for the very purpose of bringing about this consummation."


title: Dante Gabriel Rossetti

text: From the beginning of the Brotherhood's formation in 1848, their pieces of art included subjects of noble or religious disposition. Their aim was to communicate a message of "moral reform" through the style of their works, exhibiting a "truth to nature". Specifically in Rossetti's "Hand and Soul," written in 1849, he displays his main character Chiaro as an artist with spiritual inclinations. In the text, Chiaro's spirit appears before him in the form of a woman who instructs him to "set thine hand and thy soul to serve man with God." The Rossetti Archive defines this text as "Rossetti's way of constellating his commitments to art, religious devotion, and a thoroughly secular historicism." Likewise, in "The Blessed Damozel," written between 1847 and 1870, Rossetti uses biblical language such as "From the gold bar of Heaven" to describe the Damozel looking down to Earth from Heaven. Here we see a connection between body and soul, mortal and supernatural, a common theme in Rossetti's works. In "Ave" (1847), Mary awaits the day that she will meet her son in Heaven, uniting the earthly with the heavenly. The text highlights a strong element in Anglican Marian theology that describes Mary's body and soul having been assumed into Heaven. William Michael Rossetti, his brother, wrote in 1895: "He was never confirmed, professed no religious faith, and practised no regular religious observances; but he had ... sufficient sympathy with the abstract ideas and the venerable forms of Christianity to go occasionally to an Anglican church — very occasionally, and only as the inclination ruled him."


title: Dante Gabriel Rossetti

text: Around 1860, Rossetti returned to oil painting, abandoning the dense medieval compositions of the 1850s in favour of powerful close-up images of women in flat pictorial spaces characterised by dense colour. These paintings became a major influence on the development of the European Symbolist movement. In them, Rossetti's depiction of women became almost obsessively stylised. He portrayed his new lover Fanny Cornforth as the epitome of physical eroticism, whilst Jane Burden, the wife of his business partner William Morris, was glamorised as an ethereal goddess. "As in Rossetti's previous reforms, the new kind of subject appeared in the context of a wholesale reconfiguration of the practice of painting, from the most basic level of materials and techniques up to the most abstract or conceptual level of the meanings and ideas that can be embodied in visual form." These new works were based not on medievalism, but on the Italian High Renaissance artists of Venice, Titian and Veronese.


title: Dante Gabriel Rossetti

text: In 1861, Rossetti became a founding partner in the decorative arts firm, Morris, Marshall, Faulkner & Co. with Morris, Burne-Jones, Ford Madox Brown, Philip Webb, Charles Faulkner and Peter Paul Marshall. Rossetti contributed designs for stained glass and other decorative objects.


title: Dante Gabriel Rossetti

text: Rossetti's wife, Elizabeth, died of an overdose of laudanum in 1862, possibly a suicide, shortly after giving birth to a stillborn child. Rossetti became increasingly depressed, and on the death of his beloved Lizzie, buried the bulk of his unpublished poems with her at Highgate Cemetery, though he later had them dug up. He idealised her image as Dante's Beatrice in a number of paintings, such as "Beata Beatrix".


title: Dante Gabriel Rossetti

text: After the death of his wife, Rossetti leased a Tudor House at 16, Cheyne Walk, in Chelsea, where he lived for 20 years surrounded by extravagant furnishings and a parade of exotic birds and animals. Rossetti was fascinated with wombats, asking friends to meet him at the "Wombat's Lair" at the London Zoo in Regent's Park, and spending hours there. In September 1869, he acquired the first of two pet wombats, which he named "Top". It was brought to the dinner table and allowed to sleep in the large centrepiece during meals. Rossetti's fascination with exotic animals continued throughout his life, culminating in the purchase of a llama and a toucan, which he dressed in a cowboy hat and trained to ride the llama round the dining-table for his amusement.


title: Dante Gabriel Rossetti

text: Rossetti maintained Fanny Cornforth (described delicately by William Allington as Rossetti's "housekeeper") in her own establishment nearby in Chelsea, and painted many voluptuous images of her between 1863 and 1865.


title: Dante Gabriel Rossetti

text: In 1865, he discovered auburn-haired Alexa Wilding, a dressmaker and would-be actress who was engaged to model for him on a full-time basis and sat for "Veronica Veronese", "The Blessed Damozel", "A Sea–Spell", and other paintings. She sat for more of his finished works than any other model, but comparatively little is known about her due to the lack of any romantic connection with Rossetti. He spotted her one evening in the Strand in 1865 and was immediately struck by her beauty. She agreed to sit for him the following day, but failed to arrive. He spotted her again weeks later, jumped from the cab he was in and persuaded her to go straight to his studio. He paid her a weekly fee to sit for him exclusively, afraid that other artists might employ her. They shared a lasting bond; after Rossetti's death Wilding was said to have travelled regularly to place a wreath on his grave.


title: Dante Gabriel Rossetti

text: Jane Morris, whom Rossetti had used as a model for the Oxford Union murals he painted with William Morris and Edward Burne-Jones in 1857, also sat for him during these years, she "consumed and obsessed him in paint, poetry, and life". Jane Morris was also photographed by John Robert Parsons, whose photographs were painted by Rossetti. In 1869, Morris and Rossetti rented a country house, Kelmscott Manor at Kelmscott, Oxfordshire, as a summer home, but it became a retreat for Rossetti and Jane Morris to have a long-lasting and complicated liaison. They spent summers there with the Morrises' children, while William Morris travelled to Iceland in 1871 and 1873.


title: Dante Gabriel Rossetti

text: During these years, Rossetti was prevailed upon by friends, in particular Charles Augustus Howell, to exhume his poems from his wife's grave which he did, collating and publishing them in 1870 in the volume "Poems by D. G. Rossetti". They created controversy when they were attacked as the epitome of the "fleshly school of poetry". Their eroticism and sensuality caused offence. One poem, "Nuptial Sleep", described a couple falling asleep after sex. It was part of Rossetti's sonnet sequence "The House of Life", a complex series of poems tracing the physical and spiritual development of an intimate relationship. Rossetti described the sonnet form as a "moment's monument", implying that it sought to contain the feelings of a fleeting moment, and reflect on their meaning. "The House of Life" was a series of interacting monuments to these moments – an elaborate whole made from a mosaic of intensely described fragments. It was Rossetti's most substantial literary achievement. The collection included some translations, including his "Ballad Of Dead Ladies", an 1869 translation of François Villon's poem "Ballade des dames du temps jadis". (The word "yesteryear" is credited to Rossetti as a neologism used for the first time in this translation.)


title: Dante Gabriel Rossetti

text: In 1881, Rossetti published a second volume of poems, "Ballads and Sonnets", which included the remaining sonnets from "The House of Life" sequence.


title: Dante Gabriel Rossetti

text: The savage reaction of critics to Rossetti's first collection of poetry contributed to a mental breakdown in June 1872, and although he joined Jane Morris at Kelmscott that September, he "spent his days in a haze of chloral and whisky". The next summer he was much improved, and both Alexa Wilding and Jane sat for him at Kelmscott, where he created a soulful series of dream-like portraits. In 1874, Morris reorganised his decorative arts firm, cutting Rossetti out of the business, and the polite fiction that both men were in residence with Jane at Kelmscott could not be maintained. Rossetti abruptly left Kelmscott in July 1874 and never returned. Toward the end of his life, he sank into a morbid state, darkened by his drug addiction to chloral hydrate and increasing mental instability. He spent his last years as a recluse at Cheyne Walk.


title: Dante Gabriel Rossetti

text: On Easter Sunday, 1882, he died at the country house of a friend, where he had gone in a vain attempt to recover his health, which had been destroyed by chloral as his wife's had been destroyed by laudanum. He died of Bright's Disease, a disease of the kidneys from which he had been suffering for some time. He had been housebound for some years on account of paralysis of the legs, though his chloral addiction is believed to have been a means of alleviating pain from a botched hydrocele removal. He had been suffering from alcohol psychosis for some time brought on by the excessive amounts of whisky he used to drown out the bitter taste of the chloral hydrate. He is buried in the churchyard of All Saints at Birchington-on-Sea, Kent, England.


title: Dante Gabriel Rossetti

text: Tate Britain, Birmingham, Manchester, Salford Museum and Art Galleries and Wightwick Manor National Trust, all contain large collections of Rossetti's work; Salford was bequeathed a number of works following the death of L. S. Lowry in 1976. Lowry was president of the Newcastle-based 'Rossetti Society', which was founded in 1966. Lowry's private collection of works was chiefly built around Rossetti's paintings and sketches of Lizzie Siddal and Jane Morris, and notable pieces included "Pandora", " Proserpine" and a drawing of Annie Miller.


title: Dante Gabriel Rossetti

text: In an interview with Mervyn Levy, Lowry explained his fascination with the Rossetti women in relation to his own work: "I don't like his women at all, but they fascinate me, like a snake. That's why I always buy Rossetti whenever I can. His women are really rather horrible. It's like a friend of mine who says he hates my work, although it fascinates him." The friend Lowry referred to was businessman Monty Bloom, to whom he also explained his obsession with Rossetti's portraits: "They are not real women.[...] They are dreams.[...] He used them for something in his mind caused by the death of his wife. I may be quite wrong there, but significantly they all came after the death of his wife."


title: Dante Gabriel Rossetti

text: The popularity, frequent reproduction, and general availability of Rossetti's later paintings of women have led to this association with "a morbid and languorous sensuality". His small-scale early works and drawings are less well known, but it is in these that his originality, technical inventiveness, and significance in the movement away from Academic tradition can best be seen. As Roger Fry wrote in 1916, "Rossetti more than any other artist since Blake may be hailed as a forerunner of the new ideas" in English Art.


title: Dante Gabriel Rossetti

text: Rossetti was played by Oliver Reed in Ken Russell's television film "Dante's Inferno" (1967). The Pre-Raphaelite Brotherhood has been the subject of two BBC period dramas. The first, "The Love School", (1975) features Ben Kingsley as Rossetti. The second was "Desperate Romantics", in which Rossetti is played by Aidan Turner. It was broadcast on BBC Two on Tuesday, 21 July 2009.


title: Dante Gabriel Rossetti

text: Dr. Frasier Crane (Kelsey Grammer) appears in an episode of "Cheers" as Dante Gabriel Rossetti for his Hallowe'en costume. His wife Dr. Lilith Sternin-Crane appears as Rossetti's sister, Christina. Their son Frederick is dressed as Spiderman.


title: Dante Gabriel Rossetti

text: Gabriel Rossetti and other members of the Rossetti family are characters in Tim Powers' novel "Hide Me Among the Graves," in which both the Rossettis' uncle John Polidori and Gabriel's wife Lizzie act as hosts for vampiric beings, and whose influence inspires the artistic genius of the family.


title: Dante Gabriel Rossetti

text: Rossetti's poem "The Blessed Damozel" was the inspiration for Claude Debussy's cantata "La Damoiselle élue" (1888).


title: Dante Gabriel Rossetti

text: John Ireland (18791962) set to music as one of his "Three Songs" (1926), Rossetti's poem "The One Hope" from "Poems" (1870).


title: Dante Gabriel Rossetti

text: In 1904 Ralph Vaughan Williams (1872-1958) created his song cycle "The House of Life" from six poems by Rossetti. One song in that cycle, Silent Noon, is one of Vaughan Williams's best known and most frequently performed songs.


title: Dante Gabriel Rossetti

text: In 1904, Phoebe Anna Traquair painted "The Awakening", inspired by a sonnet from Rossetti's "The House of Life".


title: Dante Gabriel Rossetti

text: There is evidence to suggest that a number of paintings by Paula Modersohn-Becker (1876-1907) were influenced by the Pre-Raphaelite painter Dante Rossetti.


title: Dante Gabriel Rossetti

text: The 1990s grunge band Hole used lines from Rossetti's "Superscription", from "House of Life", in their song "Celebrity Skin" from their album "Celebrity Skin": while Rossetti's line read "Look in my face; my name is Might-have-been" the Hole lyric is "Look at my face; my name is Might-have-been."


title: Dante Gabriel Rossetti

text: "Rossetti divided his attention between painting and poetry for the rest of his life" - Poetry Foundation


title: Hemiptera

text: Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to around , and share a common arrangement of piercing-sucking mouthparts. The name "true bugs" is often limited to the suborder Heteroptera.


title: Hemiptera

text: Entomologists reserve the term "bug" for Hemiptera or Heteroptera, which does not include insects of other orders such as ants, bees, beetles, or butterflies. In some variations of English, all terrestrial arthropods (including non-insect arachnids, and myriapods) also fall under the colloquial understanding of "bug".


title: Hemiptera

text: Many insects with "bug" in their common name, especially in American English, belong to other orders; for example, the lovebug is a fly and the Maybug and ladybug are beetles. The term is also occasionally extended to colloquial names for freshwater or marine crustaceans (e.g. Balmain bug, Moreton Bay bug, mudbug) and used by physicians and bacteriologists for disease-causing germs (e.g. superbugs).


title: Hemiptera

text: Most hemipterans feed on plants, using their sucking and piercing mouthparts to extract plant sap. Some are bloodsucking, or hematophagous, while others are predators that feed on other insects or small invertebrates. They live in a wide variety of habitats, generally terrestrial, though some are adapted to life in or on the surface of fresh water (e.g. pondskaters, water boatmen, giant water bugs). Hemipterans are hemimetabolous, with young nymphs that somewhat resemble adults. Many aphids are capable of parthenogenesis, producing young from unfertilised eggs; this helps them to reproduce extremely rapidly in favourable conditions.


title: Hemiptera

text: Humans have interacted with the Hemiptera for millennia. Some species, including many aphids, are significant agricultural pests, damaging crops by the direct action of sucking sap, but also harming them indirectly by being the vectors of serious viral diseases. Other species have been used for biological control of insect pests or of invasive plants. A few hemipterans have been cultivated for the extraction of dyestuffs such as cochineal and carmine, and for shellac. The bed bug is a persistent parasite of humans, and some kissing bugs can transmit Chagas disease. Cicadas have been used as food, and have appeared in literature since the "Iliad" in Ancient Greece.


title: Hemiptera

text: Hemiptera is the largest order of hemimetabolous insects (not undergoing complete metamorphosis; though some examples such as male scale insects do undergo a form of complete metamorphosis ), containing over 95,000 named species. Other insect orders with more species are all holometabolous, meaning they have a pupal stage and undergo complete metamorphosis. The majority of species are terrestrial, including a number of important agricultural pests, but some are found in freshwater habitats. These include the water boatmen, backswimmers, pond skaters, and giant water bugs.


title: Hemiptera

text: Hemiptera belong to the insect superorder Paraneoptera, which includes lice (Psocodea), thrips (Thysanoptera), and the true bugs of Hemiptera. Within Paraneoptera, Hemiptera is most closely related to the sister clade Thysanoptera.


title: Hemiptera

text: The fossil record of hemipterans goes back to the Carboniferous (Moscovian). The oldest fossils are of the Archescytinidae from the Lower Permian and are thought to be basal to the Auchenorrhyncha. Fulgoromorpha and Cicadomorpha appear in the Upper Permian, as do Sternorrhyncha of the Psylloidea and Aleyrodoidea. Aphids and Coccoids appear in the Triassic. The Coleorrhyncha extend back to the Lower Jurassic. The Heteroptera first appeared in the Triassic.


title: Hemiptera

text: The present members of the order Hemiptera (sometimes referred to as Rhynchota) were historically placed into two orders, the so-called Homoptera and Heteroptera/Hemiptera, based on differences in wing structure and the position of the rostrum. The order is now divided into four suborders, after the "Homoptera" were established as paraphyletic (now the Auchenorrhyncha and the Sternorrhyncha).


title: Hemiptera

text: The below cladogram shows Hemiptera's placement within Paraneoptera, as well as how Hemiptera's four suborders are related. English names are given in parentheses where possible.


title: Hemiptera

text: The defining feature of hemipterans is their "beak" in which the modified mandibles and maxillae form a "stylet" which is sheathed within a modified labium. The stylet is capable of piercing tissues and sucking liquids, while the labium supports it. The stylet contains a channel for the outward movement of saliva and another for the inward movement of liquid food. A salivary pump drives saliva into the prey; a cibarial pump extracts liquid from the prey. Both pumps are powered by substantial dilator muscles in the head. The beak is usually folded under the body when not in use. The diet is typically plant sap, but some hemipterans such as assassin bugs are predators.


title: Hemiptera

text: Both herbivorous and predatory hemipterans inject enzymes to begin digestion extra-orally (before the food is taken into the body). These enzymes include amylase to hydrolyse starch, polygalacturonase to weaken the tough cell walls of plants, and proteinases to break down proteins.


title: Hemiptera

text: Although the Hemiptera vary widely in their overall form, their mouthparts form a distinctive "rostrum". Other insect orders with mouthparts modified into anything like the rostrum and stylets of the Hemiptera include some Phthiraptera, but for other reasons they generally are easy to recognize as non-hemipteran. Similarly, the mouthparts of Siphonaptera, some Diptera and Thysanoptera superficially resemble the rostrum of the Hemiptera, but on closer inspection the differences are considerable. Aside from the mouthparts, various other insects can be confused with Hemiptera, but they all have biting mandibles and maxillae instead of the rostrum. Examples include cockroaches and psocids, both of which have longer, many-segmented antennae, and some beetles, but these have fully hardened forewings which do not overlap.


title: Hemiptera

text: The forewings of Hemiptera are either entirely membranous, as in the Sternorrhyncha and Auchenorrhyncha, or partially hardened, as in most Heteroptera. The name "Hemiptera" is from the Greek ('; "half") and ('; "wing"), referring to the forewings of many heteropterans which are hardened near the base, but membranous at the ends. Wings modified in this manner are termed "hemelytra" (singular: "hemelytron"), by analogy with the completely hardened elytra of beetles, and occur only in the suborder Heteroptera. In all suborders, the hindwings – if present at all – are entirely membranous and usually shorter than the forewings. The forewings may be held "roofwise" over the body (typical of Sternorrhyncha and Auchenorrhyncha), or held flat on the back, with the ends overlapping (typical of Heteroptera). The antennae in Hemiptera typically consist of four or five segments, although they can still be quite long, and the tarsi of the legs have two or three segments.


title: Hemiptera

text: Many hemipterans can produce sound for communication. The "song" of male cicadas, the loudest of any insect, is produced by tymbal organs on the underside of the abdomen, and is used to attract mates. The tymbals are drumlike disks of cuticle, which are clicked in and out repeatedly, making a sound in the same way as popping the metal lid of a jam jar in and out.


title: Hemiptera

text: Stridulatory sounds are produced among the aquatic Corixidae and Notonectidae (backswimmers) using tibial combs rubbed across rostral ridges.


title: Hemiptera

text: Hemipterans are hemimetabolous, meaning that they do not undergo metamorphosis, the complete change of form between a larval phase and an adult phase. Instead, their young are called nymphs, and resemble the adults to a greater or lesser degree. The nymphs moult several times as they grow, and each instar resembles the adult more than the previous one. Wing buds grow in later stage nymphs; the final transformation involves little more than the development of functional wings (if they are present at all) and functioning sexual organs, with no intervening pupal stage as in holometabolous insects.


title: Hemiptera

text: Many aphids are parthenogenetic during part of the life cycle, such that females can produce unfertilized eggs, which are clones of their mother. All such young are females (thelytoky), so 100% of the population at these times can produce more offspring. Many species of aphid are also viviparous: the young are born live rather than laid as eggs. These adaptations enable aphids to reproduce extremely rapidly when conditions are suitable.


title: Hemiptera

text: Hemipterans make use of a variety of modes of locomotion including swimming, skating on a water surface and jumping, as well as walking and flying like other insects.


title: Hemiptera

text: Several families of Heteroptera are "water bugs", adapted to an aquatic lifestyle, such as the water boatmen (Corixidae), water scorpions (Nepidae), and backswimmers (Notonectidae). They are mostly predatory, and have legs adapted as paddles to help the animal move through the water. The pondskaters or water striders (Gerridae) are also associated with water, but use the surface tension of standing water to keep them above the surface; they include the sea skaters in the genus "Halobates", the only truly marine group of insects.


title: Hemiptera

text: Marangoni effect propulsion exploits the change in surface tension when a soap-like surfactant is released on to a water surface, in the same way that a toy soap boat propels itself. Water bugs in the genus "Microvelia" (Veliidae) can travel at up to 17 cm/s, twice as fast as they can walk, by this means.


title: Hemiptera

text: Flight is well developed in the Hemiptera although mostly used for short distance movement and dispersal. Wing development is sometimes related to environmental conditions. In some groups of Hemiptera, there are variations of winged, short-winged, and wingless forms within a single species. This kind of polymorphism tends to be helpful when habitats are temporary with more energy put into reproduction when food is available and into dispersal through flight when food becomes scarce. In aphids, both winged and wingless forms occur with winged forms produced in greater numbers when food resources are depleted. Aphids and whiteflies can sometimes be transported very long distances by atmospheric updrafts and high altitude winds. Wing-length polymorphism is notably rare in tree-living Hemiptera.


title: Hemiptera

text: Many Auchenorrhyncha including representatives of the cicadas, leafhoppers, treehoppers, planthoppers, and froghoppers are adapted for jumping (saltation). Treehoppers, for example, jump by rapidly depressing their hind legs. Before jumping, the hind legs are raised and the femora are pressed tightly into curved indentations in the coxae. Treehoppers can attain a take-off velocity of up to 2.7 metres per second and an acceleration of up to 250 g. The instantaneous power output is much greater than that of normal muscle, implying that energy is stored and released to catapult the insect into the air. Cicadas, which are much larger, extend their hind legs for a jump in under a millisecond, again implying elastic storage of energy for sudden release.


title: Hemiptera

text: Instead of relying on any form of locomotion, most Sternorrhyncha females are sedentary or completely sessile, attached to their host plants by their thin feeding stylets which cannot be taken out of the plant quickly.


title: Hemiptera

text: Most hemipterans are phytophagous, using their sucking and piercing mouthparts to feed on plant sap. These include cicadas, leafhoppers, treehoppers, planthoppers, froghoppers, aphids, whiteflies, scale insects, and some other groups. Some are monophages, being host specific and only found on one plant taxon, others are oligophages, feeding on a few plant groups, while others again are less discriminating polyphages and feed on many species of plant. The relationship between hemipterans and plants appears to be ancient, with piercing and sucking of plants evident in the Early Devonian period.


title: Hemiptera

text: Hemipterans can dramatically cut the mass of affected plants, especially in major outbreaks. They sometimes also change the mix of plants by predation on seeds or feeding on roots of certain species. Some sap-suckers move from one host to another at different times of year. Many aphids spend the winter as eggs on a woody host plant and the summer as parthogenetically reproducing females on a herbaceous plant.


title: Hemiptera

text: Phloem sap, which has a higher concentration of sugars and nitrogen, is under positive pressure unlike the more dilute xylem sap. Most of the Sternorrhyncha and a number of Auchenorrhynchan groups feed on phloem. Phloem feeding is common in the Fulgoromorpha, most Cicadellidae and in the Heteroptera.


title: Hemiptera

text: The Typhlocybine Cicadellids specialize in feeding on non-vascular mesophyll tissue of leaves, which is more nutritious than the leaf epidermis. Most Heteroptera also feed on mesophyll tissue where they are more likely to encounter defensive secondary plant metabolites which often leads to the evolution of host specificity.


title: Hemiptera

text: Obligate xylem feeding is a special habit that is found in the Auchenorrhyncha among Cicadoidea, Cercopoidea and in Cicadelline Cicadellids. Some phloem feeders may take to xylem sap facultatively, especially when facing dehydration. Xylem feeders tend to be polyphagous; to overcome the negative pressure of xylem requires a special cibarial pump.


title: Hemiptera

text: Phloem feeding hemiptera typically have symbiotic micro-organisms in their gut that help to convert amino acids. Phloem feeders produce honeydew from their anus. A variety of organisms that feed on honeydew form symbiotic associations with phloem-feeders. Phloem sap is a sugary liquid low in amino acids, so insects have to process large quantities to meet their nutritional requirements. Xylem sap is even lower in amino acids and contains monosaccharides rather than sucrose, as well as organic acids and minerals. No digestion is required (except for the hydrolysis of sucrose) and 90% of the nutrients in the xylem sap can be utilised. Some phloem sap feeders selectively mix phloem and xylem sap to control the osmotic potential of the liquid consumed.


title: Hemiptera

text: A striking adaptation to a very dilute diet is found in many hemipterans: a filter chamber, a part of the gut looped back on itself as a countercurrent exchanger, which permits nutrients to be separated from excess water. The residue, mostly water with sugars and amino acids, is quickly excreted as sticky "honey dew", notably from aphids but also from other Auchenorrhycha and Sternorrhyncha.


title: Hemiptera

text: Some Sternorrhyncha including Psyllids and some aphids are gall formers. These sap-sucking hemipterans inject fluids containing plant hormones into the plant tissues inducing the production of tissue that covers to protects the insect and also act as sinks for nutrition that they feed on. The hackleberry gall psyllid for example, causes a woody gall on the leaf petioles of the hackleberry tree it infests, and the nymph of another psyllid produces a protective lerp out of hardened honeydew.


title: Hemiptera

text: Most other hemipterans are predatory, feeding on other insects, or even small vertebrates. This is true of many aquatic species which are predatory, either as nymphs or adults. The predatory shield bug for example stabs caterpillars with its beak and sucks out the body fluids. The saliva of predatory heteropterans contains digestive enzymes such as proteinase and phospholipase, and in some species also amylase. The mouthparts of these insects are adapted for predation. There are toothed stylets on the mandibles able to cut into and abrade tissues of their prey. There are further stylets on the maxillae, adapted as tubular canals to inject saliva and to extract the pre-digested and liquified contents of the prey.


title: Hemiptera

text: Some species attack pest insects and are used in biological control. One of these is the spined soldier bug ("Podisus maculiventris") that sucks body fluids from larvae of the Colorado beetle and the Mexican bean beetle.


title: Hemiptera

text: A few hemipterans are haematophagic (often described as "parasites"), feeding on the blood of larger animals. These include bedbugs and the triatomine kissing bugs of the assassin bug family Reduviidae, which can transmit the dangerous "Chagas disease". The first known hemipteran to feed in this way on vertebrates was the extinct assassin bug "Triatoma dominicana" found fossilized in amber and dating back about twenty million years. Faecal pellets fossilised beside it show that it transmitted a disease-causing "Trypanosoma" and the amber included hairs of the likely host, a bat.


title: Hemiptera

text: Some species of ant protect and farm aphids (Sternorrhyncha) and other sap-sucking hemipterans, gathering and eating the honeydew that these hemipterans secrete. The relationship is mutualistic, as both ant and aphid benefit. Ants such as the yellow anthill ant, "Lasius flavus", breed aphids of at least four species, "Geoica utricularia", "Tetraneura ulmi", "Forda marginata" and "Forda formicaria", taking eggs with them when they found a new colony; in return, these aphids are obligately associated with the ant, breeding mainly or wholly asexually inside anthills. Ants may also protect the plant bugs from their natural enemies, removing the eggs of predatory beetles and preventing access by parasitic wasps.


title: Hemiptera

text: Some leafhoppers (Auchenorrhyncha) are similarly "milked" by ants. In the Corcovado rain forest of Costa Rica, wasps compete with ants to protect and milk leafhoppers; the leafhoppers preferentially give more honeydew, more often, to the wasps, which are larger and may offer better protection.


title: Hemiptera

text: Hemiptera form prey to predators including vertebrates, such as birds, and other invertebrates such as ladybirds. In response, hemipterans have evolved antipredator adaptations. "Ranatra" may feign death (thanatosis). Others such as "Carpocoris purpureipennis" secrete toxic fluids to ward off arthropod predators; some Pentatomidae such as "Dolycoris" are able to direct these fluids at an attacker. Toxic cardenolide compounds are accumulated by the heteropteran "Oncopeltus fasciatus" when it consumes milkweeds, while the coreid stinkbug "Amorbus rubiginosus" acquires 2-hexenal from its food plant, "Eucalyptus". Some long-legged bugs mimic twigs, rocking to and fro to simulate the motion of a plant part in the wind. The nymph of the Masked hunter bug camouflages itself with sand grains, using its hind legs and tarsal fan to form a double layer of grains, coarser on the outside. The Amazon rain forest cicada "Hemisciera maculipennis" displays bright red deimatic flash coloration on its hindwings when threatened; the sudden contrast helps to startle predators, giving the cicada time to escape. The coloured patch on the hindwing is concealed at rest by an olive green patch of the same size on the forewing, enabling the insect to switch rapidly from cryptic to deimatic behaviour.


title: Hemiptera

text: Some hemipterans such as firebugs have bold aposematic warning coloration, often red and black, which appear to deter passerine birds. Many hemipterans including aphids, scale insects and especially the planthoppers secrete wax to protect themselves from threats such as fungi, parasitoidal insects and predators, as well as abiotic factors like desiccation. Hard waxy coverings are especially important in the sedentary Sternorrhyncha such as scale insects, which have no means of escaping from predators; other Sternorrhyncha evade detection and attack by creating and living inside plant galls. Nymphal Cicadoidea and Cercopoidea have glands attached to the Malpighian tubules in their proximal segment that produce mucopolysaccharides, which form the froth around spittlebugs, offering a measure of protection.


title: Hemiptera

text: Parental care is found in many species of Hemiptera especially in members of the Membracidae and numerous Heteroptera. In many species of shield bug, females stand guard over their egg clusters to protect them from egg parasitoids and predators. In the aquatic Belostomatidae, females lay their eggs on the back of the male which guards the eggs. Protection provided by ants is common in the Auchenorrhyncha.


title: Hemiptera

text: Although many species of Hemiptera are significant pests of crops and garden plants, including many species of aphid and scale insects, other species are harmless. The damage done is often not so much the deprivation of the plant of its sap, but the fact that they transmit serious viral diseases between plants. They often produce copious amounts of honeydew which encourages the growth of sooty mould. Significant pests include the cottony cushion scale, a pest of citrus fruit trees, the green peach aphid and other aphids which attack crops worldwide and transmit diseases, and jumping plant lice which are often host plant-specific and transmit diseases.


title: Hemiptera

text: Members of the families Reduviidae, Phymatidae and Nabidae are obligate predators. Some predatory species are used in biological pest control; these include various nabids, and even some members of families that are primarily phytophagous, such as the genus "Geocoris" in the family Lygaeidae. Other hemipterans are omnivores, alternating between a plant-based and an animal-based diet. For example, "Dicyphus hesperus" is used to control whitefly on tomatoes but also sucks sap, and if deprived of plant tissues will die even if in the presence of whiteflies.


title: Hemiptera

text: Other hemipterans have positive uses for humans, such as in the production of the dyestuff carmine (cochineal). The FDA has created guidelines for how to declare when it has been added to a product. The scale insect "Dactylopius coccus" produces the brilliant red-coloured carminic acid to deter predators. Up to 100,000 scale insects need to be collected and processed to make a kilogram (2.2 lbs) of cochineal dye. A similar number of lac bugs are needed to make a kilogram of shellac, a brush-on colourant and wood finish. Additional uses of this traditional product include the waxing of citrus fruits to extend their shelf-life, and the coating of pills to moisture-proof them, provide slow-release or mask the taste of bitter ingredients.


title: Hemiptera

text: Chagas disease is a modern-day tropical disease caused by "Trypanosoma cruzi" and transmitted by kissing bugs, so-called because they suck human blood from around the lips while a person sleeps.


title: Hemiptera

text: The bed bug, "Cimex lectularius", is an external parasite of humans. It lives in bedding and is mainly active at night, feeding on human blood, generally without being noticed. Bed bugs mate by traumatic insemination; the male pierces the female's abdomen and injects his sperm into a secondary genital structure, the spermalege. The sperm travel in the female's blood (haemolymph) to sperm storage structures (seminal conceptacles); they are released from there to fertilise her eggs inside her ovaries.


title: Hemiptera

text: Some larger hemipterans such as cicadas are used as food in Asian countries such as China, and they are much esteemed in Malawi and other African countries. Insects have a high protein content and good food conversion ratios, but most hemipterans are too small to be a useful component of the human diet. At least nine species of Hemiptera are eaten worldwide.


title: Hemiptera

text: Cicadas have featured in literature since the time of Homer's "Iliad", and as motifs in decorative art from the Chinese Shang dynasty (1766–1122 B.C.). They are described by Aristotle in his "History of Animals" and by Pliny the Elder in his "Natural History"; their mechanism of sound production is mentioned by Hesiod in his poem "Works and Days" "when the Skolymus flowers, and the tuneful "Tettix" sitting on his tree in the weary summer season pours forth from under his wings his shrill song".


title: Hemiptera

text: Among the bugs, cicadas in particular have been used as money, in folk medicine, to forecast the weather, to provide song (in China), and in folklore and myths around the world.


title: Hemiptera

text: Large-scale cultivation of the oil palm "Elaeis guineensis" in the Amazon basin damages freshwater habitats and reduces the diversity of aquatic and semi-aquatic Heteroptera. Climate change may be affecting the global migration of hemipterans including the potato leafhopper, "Empoasca fabae". Warming is correlated with the severity of potato leafhopper infestation, so increased warming may worsen infestations in future.


title: Chemical substance

text: A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be simple substances (substances consisting of a single chemical element), chemical compounds, or alloys.


title: Chemical substance

text: Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.


title: Chemical substance

text: Chemical substances exist as solids, liquids, gases, or plasma, and may change between these phases of matter with changes in temperature or pressure and time. Chemical substances may be combined or converted to others by means of chemical reactions.


title: Chemical substance

text: A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook. According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties. The chemical substance index published by CAS also includes several alloys of uncertain composition. Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".


title: Chemical substance

text: In geology, substances of uniform composition are called minerals, while physical mixtures (aggregates) of several minerals (different substances) are defined as rocks. Many minerals, however, mutually dissolve into solid solutions, such that a single rock is a uniform substance despite being a mixture in stoichiometric terms. Feldspars are a common example: anorthoclase is an alkali aluminum silicate, where the alkali metal is interchangeably either sodium or potassium.


title: Chemical substance

text: In law, "chemical substances" may include both pure substances and mixtures with a defined composition or manufacturing process. For example, the EU regulation REACH defines "monoconstituent substances", "multiconstituent substances" and "substances of unknown or variable composition". The latter two consist of multiple chemical substances; however, their identity can be established either by direct chemical analysis or reference to a single manufacturing process. For example, charcoal is an extremely complex, partially polymeric mixture that can be defined by its manufacturing process. Therefore, although the exact chemical identity is unknown, identification can be made to a sufficient accuracy. The CAS index also includes mixtures.


title: Chemical substance

text: Polymers almost always appear as mixtures of molecules of multiple molar masses, each of which could be considered a separate chemical substance. However, the polymer may be defined by a known precursor or reaction(s) and the molar mass distribution. For example, polyethylene is a mixture of very long chains of -CH- repeating units, and is generally sold in several molar mass distributions, LDPE, MDPE, HDPE and UHMWPE.


title: Chemical substance

text: The concept of a "chemical substance" became firmly established in the late eighteenth century after work by the chemist Joseph Proust on the composition of some pure chemical compounds such as basic copper carbonate. He deduced that, "All samples of a compound have the same composition; that is, all samples have the same proportions, by mass, of the elements present in the compound." This is now known as the law of constant composition. Later with the advancement of methods for chemical synthesis particularly in the realm of organic chemistry; the discovery of many more chemical elements and new techniques in the realm of analytical chemistry used for isolation and purification of elements and compounds from chemicals that led to the establishment of modern chemistry, the concept was defined as is found in most chemistry textbooks. However, there are some controversies regarding this definition mainly because the large number of chemical substances reported in chemistry literature need to be indexed.


title: Chemical substance

text: Isomerism caused much consternation to early researchers, since isomers have exactly the same composition, but differ in configuration (arrangement) of the atoms. For example, there was much speculation for the chemical identity of benzene, until the correct structure was described by Friedrich August Kekulé. Likewise, the idea of stereoisomerism – that atoms have rigid three-dimensional structure and can thus form isomers that differ only in their three-dimensional arrangement – was another crucial step in understanding the concept of distinct chemical substances. For example, tartaric acid has three distinct isomers, a pair of diastereomers with one diastereomer forming two enantiomers.


title: Chemical substance

text: An element is a chemical substance made up of a particular kind of atom and hence cannot be broken down or transformed by a chemical reaction into a different element, though it can be transmuted into another element through a nuclear reaction. This is because all of the atoms in a sample of an element have the same number of protons, though they may be different isotopes, with differing numbers of neutrons.


title: Chemical substance

text: As of 2019, there are 118 known elements, about 80 of which are stable – that is, they do not change by radioactive decay into other elements. Some elements can occur as more than a single chemical substance (allotropes). For instance, oxygen exists as both diatomic oxygen (O) and ozone (O). The majority of elements are classified as metals. These are elements with a characteristic lustre such as iron, copper, and gold. Metals typically conduct electricity and heat well, and they are malleable and ductile. Around 14 to 21 elements, such as carbon, nitrogen, and oxygen, are classified as non-metals. Non-metals lack the metallic properties described above, they also have a high electronegativity and a tendency to form negative ions. Certain elements such as silicon sometimes resemble metals and sometimes resemble non-metals, and are known as metalloids.


title: Chemical substance

text: A chemical compound is a chemical substance that is composed of a particular set of atoms or ions. Two or more elements combined into one substance through a chemical reaction form a chemical compound. All compounds are substances, but not all substances are compounds.


title: Chemical substance

text: A chemical compound can be either atoms bonded together in molecules or crystals in which atoms, molecules or ions form a crystalline lattice. Compounds based primarily on carbon and hydrogen atoms are called organic compounds, and all others are called inorganic compounds. Compounds containing bonds between carbon and a metal are called organometallic compounds.


title: Chemical substance

text: Compounds in which components share electrons are known as covalent compounds. Compounds consisting of oppositely charged ions are known as ionic compounds, or salts.


title: Chemical substance

text: Coordination complexes are compounds where a dative bond keeps the substance together without a covalent or ionic bond. Coordination complexes are distinct substances with distinct properties different from a simple mixture. Typically these have a metal, such as a copper ion, in the center and a nonmetals atom, such as the nitrogen in an ammonia molecule or oxygen in water in a water molecule, forms a dative bond to the metal center, e.g. tetraamminecopper(II) sulfate [Cu(NH)]SO·HO. The metal is known as a "metal center" and the substance that coordinates to the center is called a "ligand". However, the center does not need to be a metal, as exemplified by boron trifluoride etherate BFOEt, where the highly Lewis acidic, but nonmetallic boron center takes the role of the "metal". If the ligand bonds to the metal center with multiple atoms, the complex is called a chelate.


title: Chemical substance

text: In organic chemistry, there can be more than one chemical compound with the same composition and molecular weight. Generally, these are called isomers. Isomers usually have substantially different chemical properties, and often may be isolated without spontaneously interconverting. A common example is glucose vs. fructose. The former is an aldehyde, the latter is a ketone. Their interconversion requires either enzymatic or acid-base catalysis.


title: Chemical substance

text: However, tautomers are an exception: the isomerization occurs spontaneously in ordinary conditions, such that a pure substance cannot be isolated into its tautomers, even if these can be identified spectroscopically or even isolated in special conditions. A common example is glucose, which has open-chain and ring forms. One cannot manufacture pure open-chain glucose because glucose spontaneously cyclizes to the hemiacetal form.


title: Chemical substance

text: All matter consists of various elements and chemical compounds, but these are often intimately mixed together. Mixtures contain more than one chemical substance, and they do not have a fixed composition. In principle, they can be separated into the component substances by purely mechanical processes. Butter, soil and wood are common examples of mixtures.


title: Chemical substance

text: Grey iron metal and yellow sulfur are both chemical elements, and they can be mixed together in any ratio to form a yellow-grey mixture. No chemical process occurs, and the material can be identified as a mixture by the fact that the sulfur and the iron can be separated by a mechanical process, such as using a magnet to attract the iron away from the sulfur.


title: Chemical substance

text: In contrast, if iron and sulfur are heated together in a certain ratio (1 atom of iron for each atom of sulfur, or by weight, 56 grams (1 mol) of iron to 32 grams (1 mol) of sulfur), a chemical reaction takes place and a new substance is formed, the compound iron(II) sulfide, with chemical formula FeS. The resulting compound has all the properties of a chemical substance and is not a mixture. Iron(II) sulfide has its own distinct properties such as melting point and solubility, and the two elements cannot be separated using normal mechanical processes; a magnet will be unable to recover the iron, since there is no metallic iron present in the compound.


title: Chemical substance

text: While the term "chemical substance" is a precise technical term that is synonymous with "chemical" for chemists, the word "chemical" is used in general usage to refer to both (pure) chemical substances and mixtures (often called "compounds"), and especially when produced or purified in a laboratory or an industrial process. In other words, the chemical substances of which fruits and vegetables, for example, are naturally composed even when growing wild are not called "chemicals" in general usage. In countries that require a list of ingredients in products, the "chemicals" listed are industrially produced "chemical substances". The word "chemical" is also often used to refer to addictive, narcotic, or mind-altering drugs.


title: Chemical substance

text: Within the chemical industry, manufactured "chemicals" are chemical substances, which can be classified by production volume into bulk chemicals, fine chemicals and chemicals found in research only:


title: Chemical substance

text: The cause of the difference in production volume is the complexity of the molecular structure of the chemical. Bulk chemicals are usually much less complex. While fine chemicals may be more complex, many of them are simple enough to be sold as "building blocks" in the synthesis of more complex molecules targeted for single use, as named above. The "production" of a chemical includes not only its synthesis but also its purification to eliminate by-products and impurities involved in the synthesis. The last step in production should be the analysis of batch lots of chemicals in order to identify and quantify the percentages of impurities for the buyer of the chemicals. The required purity and analysis depends on the application, but higher tolerance of impurities is usually expected in the production of bulk chemicals. Thus, the user of the chemical in the US might choose between the bulk or "technical grade" with higher amounts of impurities or a much purer "pharmaceutical grade" (labeled "USP", United States Pharmacopeia). "Chemicals" in the commercial and legal sense may also include mixtures of highly variable composition, as they are products made to a technical specification instead of particular chemical substances. For example, gasoline is not a single chemical compound or even a particular mixture: different gasolines can have very different chemical compositions, as "gasoline" is primarily defined through source, properties and octane rating.


title: Chemical substance

text: Every chemical substance has one or more systematic names, usually named according to the IUPAC rules for naming. An alternative system is used by the Chemical Abstracts Service (CAS).


title: Chemical substance

text: Many compounds are also known by their more common, simpler names, many of which predate the systematic name. For example, the long-known sugar glucose is now systematically named 6-(hydroxymethyl)oxane-2,3,4,5-tetrol. Natural products and pharmaceuticals are also given simpler names, for example the mild pain-killer Naproxen is the more common name for the chemical compound (S)-6-methoxy-α-methyl-2-naphthaleneacetic acid.


title: Chemical substance

text: Chemists frequently refer to chemical compounds using chemical formulae or molecular structure of the compound. There has been a phenomenal growth in the number of chemical compounds being synthesized (or isolated), and then reported in the scientific literature by professional chemists around the world. An enormous number of chemical compounds are possible through the chemical combination of the known chemical elements. As of Feb 2021, about "177 million organic and inorganic substances" (including 68 million defined-sequence biopolymers) are in the scientific literature and registered in public databases. The names of many of these compounds are often nontrivial and hence not very easy to remember or cite accurately. Also it is difficult to keep the track of them in the literature. Several international organizations like IUPAC and CAS have initiated steps to make such tasks easier. CAS provides the abstracting services of the chemical literature, and provides a numerical identifier, known as CAS registry number to each chemical substance that has been reported in the chemical literature (such as chemistry journals and patents). This information is compiled as a database and is popularly known as the Chemical substances index. Other computer-friendly systems that have been developed for substance information, are: SMILES and the International Chemical Identifier or InChI.


title: Chemical substance

text: Often a pure substance needs to be isolated from a mixture, for example from a natural source (where a sample often contains numerous chemical substances) or after a chemical reaction (which often gives mixtures of chemical substances).


title: Neighbors 2: Sorority Rising

text: Neighbors 2: Sorority Rising (released in some countries as Bad Neighbours 2 and on home release as Neighbors 2) is a 2016 American comedy film directed by Nicholas Stoller and written by Stoller, Andrew J. Cohen, Brendan O'Brien, Seth Rogen and Evan Goldberg. A sequel to "Neighbors" (2014), the plot follows the Radners (Rogen and Rose Byrne) having to outwit a new sorority led by Shelby (Chloë Grace Moretz), living next door to sell their house currently in escrow. Zac Efron, Dave Franco, Christopher Mintz-Plasse, Jerrod Carmichael, Ike Barinholtz, Carla Gallo, Hannibal Buress, and Lisa Kudrow reprise their roles from the first film; it was Rogen's first live-action sequel. The film premiered on April 26, 2016, in Berlin and was released on May 20, 2016, in the United States, receiving mostly positive reviews and grossed $108 million worldwide.


title: Neighbors 2: Sorority Rising

text: Two years from the first film, Mac and Kelly Radner are having another baby, and preparing to sell their home to the Baiers family; the Radners' realtor reminds them that the house is in escrow for 30 days. Mac's friend Jimmy and his wife Paula are also expecting a baby. College freshman Shelby meets fellow freshmen Beth and Nora. Learning that sororities are not allowed to host parties, and disgusted by sexist and predatory frat parties, the trio create a new sorority, Kappa Nu, to throw their own parties.


title: Neighbors 2: Sorority Rising

text: Teddy Sanders hosts poker night with his former frat brothers. Pete has become a successful architect and come out of the closet, Scoonie has launched his own mobile app, and Garf is a rookie cop since graduating, but Teddy – due to the events of the first film – has a criminal record and cannot find a worthwhile job.


title: Neighbors 2: Sorority Rising

text: The friends help Pete's boyfriend Darren propose, leading Pete to ask Teddy to move out. Distraught, Teddy runs to the old frat house, next door to the Radners. He meets Shelby, Beth, and Nora, the girls hoping to rent the house for Kappa Nu but unable to afford it. Finding an opportunity to be valued, Teddy offers to help them throw parties, earning enough donations and new members to pay rent.


title: Neighbors 2: Sorority Rising

text: Fearing that the sorority will scare off the Baiers, Mac and Kelly ask Shelby to temporarily refrain from partying, but she refuses. The Radners go to Dean Gladstone, who cannot control an independent sorority, and Shelby's father, who also fails to help, leading Kappa Nu to prank the Radners. Mac, Kelly, Jimmy, and Paula retaliate, infesting the sorority house with bed bugs, forcing the girls to evacuate and pay for fumigation tenting, just in time for the Baiers' visit. Teddy argues with Pete about the state of his life, and moves into the sorority.


title: Neighbors 2: Sorority Rising

text: Low on funds to pay rent, the girls plan to sell marijuana at their 'tailgate party', eliminating the competition by getting all other dealers arrested. When Teddy objects, the girls kick him out, and he joins the Radners to take down Kappa Nu. They infiltrate the party, and Teddy distracts the girls while Mac steals their marijuana. Realizing Teddy's lack of direction in life, Mac and Kelly let him stay with them. The girls switch Mac and Kelly's cell phone numbers with their own, and send text messages tricking Mac into flying to Sydney, Australia. Returning home, the Radners find Kappa Nu has robbed and vandalized their house, and the Baiers pull out from the sale.


title: Neighbors 2: Sorority Rising

text: The sorority receives an eviction notice, and Shelby reluctantly organizes a sexually gratuitous frat-style party to raise money. As Mac and Kelly wait to call the police, Jimmy and Paula sneak into the party, while Teddy is unable to shut off the sorority's power. Shelby steals Mac and Kelly's phones and locks Mac and Teddy in the garage, but they break out using airbags. Overhearing Beth and Nora confront Shelby for compromising their original goals, Kelly encourages the girls not to give up on themselves. Paula goes into labor, and Teddy reconciles with Pete and Darren, happily agreeing to serve as their best man. The sorority enjoys a more empowering party for themselves, and discover a crowd of girls from other sororities wanting to join Kappa Nu. With an overflow of money and new members, the sorority is able to keep their home, and the Radners agree to rent their house to Kappa Nu as well, earning them a bigger cashflow than selling the house.


title: Neighbors 2: Sorority Rising

text: Three months later, Teddy prepares Pete to walk down the aisle. Teddy has become a wedding planner for gay couples, utilizing his party-planning experience. Mac and Kelly have moved into their new home, with no close neighbors, and realized they have been good parents all along. They bring home their new baby, Mildred, to meet Jimmy and Paula with their new son, Jimmy Jr.