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References for:: Aromaticityplugin-autotooltip__plain plugin-autotooltip_bigAromaticity

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The concept of 'Aromaticity' dates back to 1855, when chemist August Hofmann used the word to describe a set of benzene-like compounds that feature phenyl groups. As the name suggests, one common characteristic is that they often have distinctive; Chemical bondingplugin-autotooltip__plain plugin-autotooltip_bigChemical bonding

Chemistry textbooks normally describe three types of chemical bonds - the strong attraction between atoms, ions or molecules that enables the formation of all chemical compounds.

* The Ionic bond * The Covalent bond (see notes below); Crystallizationplugin-autotooltip__plain plugin-autotooltip_bigCrystallization

Crystallization is the process by which a solid forms from solution, where the atoms or molecules become highly organized and form a structure.

Some aspects of the process, particularly nucleation is still not completely understood, despite intensive research going back more than a century.; Metallic catalystsplugin-autotooltip__plain plugin-autotooltip_bigMetallic catalysts

The history of using metallic catalysts to speed up chemical reactions goes back to the mid 1800s. They typically make reaction rates many thousands of times faster.

Without metallic catalysts, many current-day commercial reaction processes would be impractically slow.; Polymer crystallization; Neural Networksplugin-autotooltip__plain plugin-autotooltip_bigNeural Networks

functionality_unexplained

""Multilayer neural networks are among the most powerful models in machine learning, yet the fundamental reasons for this success defy mathematical understanding."

Source : Proceedings of the National Academy of Sciences [open access]2018 115 (33)"

'Artificial Intelligence' (AI) systems predominantly use; Antarctic gravity wavesplugin-autotooltip__plain plugin-autotooltip_bigAntarctic gravity waves

Note: A 'Gravity Wave' is an atmospheric phenomenon - not to be confused with 'Gravitational Waves' which are gravity variations.

Persistent, dominant, large-amplitude Gravity Waves were discovered above Antarctica in 2016 using simultaneous LIDAR and MF radar observations.; Aviation contrails (climate impact)plugin-autotooltip__plain plugin-autotooltip_bigAviation contrails (climate impact)

Jet engines used in commercial and military aircraft typically burn carbon-based fuels (e.g. kerosene). When the fuel burns, a by-product is CO2, which is a potent greenhouse gas and contributes towards global warming.; Chandler Wobbleplugin-autotooltip__plain plugin-autotooltip_bigChandler Wobble

"The Chandler wobble is an excited resonance of the Earth's rotation having a period of about 14 months. Although it has been under investigation for more than a century, its excitation mechanism has remained elusive."

[ source link below ]; Earth's inner coreplugin-autotooltip__plain plugin-autotooltip_bigEarth's inner core

Since the 1930s, the mainstream view of the 'Inner Core' of planet Earth is that it's solid, and is composed primarily of iron, along with small percentages of nickel and some other light elements.

Since the 1980s, it has been known that the core is able to transmit seismic shear waves (transverse seismic waves) - called; Earth’s background free oscillationsplugin-autotooltip__plain plugin-autotooltip_bigEarth’s background free oscillations

Earth’s background free oscillations (a.k.a. Earth's Hum and The Seismic Hum) were discovered in 1998 using a superconducting gravimeter at Syowa Station, Antarctica, and were subsequently confirmed by more than 200 other experimental sensors worldwide. (Ref.; Environmental plastic degradationplugin-autotooltip__plain plugin-autotooltip_bigEnvironmental plastic degradation

Of the (estimated) 300 - 400 million tonnes of plastic produced worldwide every year, only around 20% is currently recycled or incinerated. Much of the remaining 80% eventually ends up in the environment.

In the environment, plastics are degraded by weathering, UV light, abrasion, and mechanical action etc - but they are also degraded by microbes (e.g.; 'Fairy circles' (ecology)plugin-autotooltip__plain plugin-autotooltip_big'Fairy circles' (ecology)

'Fairy circles' are distinct surface topology features found at various geographical locations - notably in arid areas of Namibia and Australia - where many thousands of examples have been recorded.

As the name suggests, they tend to be roughly-circular patches of land - but with no growing plants in the centres. They often have a thin border formed by tougher grass growth. They vary between 2 and 12 meters in diameter - large enough to show up on satellite imagery (; Isoprene emissions from plantsplugin-autotooltip__plain plugin-autotooltip_bigIsoprene emissions from plants

Isoprene is a simple organic molecule ( C5H8 , or, more accurately CH2=C(CH3)−CH=CH2 ) which is emitted into the atmosphere by (some) plants - notably oaks, poplars, eucalyptus and pines. The first report of isoprene emissions from plants was published in 1957.; Lightningplugin-autotooltip__plain plugin-autotooltip_bigLightning

High powered lightning discharges are happening somewhere on Earth around 100 times every second.

A possible mechanism for the very substantial electrical charges within the clouds was put forward in 1978. Following lab-based experiments, it was suggested that the charges arise from the static-electric interactions of graupel (slush) and ice crystals moving within the cloud (due to convection currents caused by widely differing air temperatures) .; Messinian salinity crisisplugin-autotooltip__plain plugin-autotooltip_bigMessinian salinity crisis

The Messianian Salinity Crisis refers to very large deposits of sea salt found in the Mediterranean region, about 1km below the current sea bed. (Named after Messina, a southern Italian city, where the deposits were first identified); Ozone Depletion Eventsplugin-autotooltip__plain plugin-autotooltip_bigOzone Depletion Events

The Earth's Troposphere regularly experiences (naturally occurring *) ozone depletion events. The presence of atmospheric ozone is of extreme importance to organic life, as it substantially 'filters out' a large proportion of dangerous UV radiation from the Sun before it reaches the Earth's surface.; Raindrop formationplugin-autotooltip__plain plugin-autotooltip_bigRaindrop formation

"When [an] ascending parcel of moist air reaches the condensation level, the initial mist of small, micron-size water droplets is formed, which are suspended in the air. In the super-saturated environment water droplets grow due to condensation of water vapor from the surrounding atmosphere. However, to form the raindrops, which can fall down triggering rain, they must grow up to about 50μm size droplets, which would take a very long time. Observations indicate that the aver…; Rock salt depositsplugin-autotooltip__plain plugin-autotooltip_bigRock salt deposits

Rock salt (a.k.a. Halite) deposits on Earth are extremely common, with many very extensive deposits thousands of metres deep, and probably totaling trillions of tonnes * See note below.

In geological 'textbook' terms, rock salt deposits are normally classed as an; Sea slopesplugin-autotooltip__plain plugin-autotooltip_bigSea slopes

Global Mean Sea Level is an averaged measure. The averaging has to take account of local temporary factors such as the tidal flows, windspeed, sea currents, etc. etc.. It also allows for the permanent effects of the Earth's rotation - whereby the poles are 'flattened'. And factors-in corrections for the curvature of the Earth.; Sea Surface Microlayerplugin-autotooltip__plain plugin-autotooltip_bigSea Surface Microlayer

The Sea Surface Microlayer (SSM) or Sea Surface Layer (SSL) is defined as the top 1 micron > 1mm 'layer' of the Earth's oceans. It's thought that the layer behaves differently to the main body of the ocean, acting as the 'interface' between the atmosphere and the seawater beneath.; Tectonic subductionplugin-autotooltip__plain plugin-autotooltip_bigTectonic subduction

Movements of the 'Tectonic Plates' are believed to have formed almost all of the Earth's current-day crust - relying on a process called 'Subduction'.

In that process, the oceanic lithosphere of a tectonic plate collides with the less dense lithosphere of a second plate. Under pressure, the heavier plate slides under the second plate and sinks down into the mantle. See; Terrestrial gamma-ray flashesplugin-autotooltip__plain plugin-autotooltip_bigTerrestrial gamma-ray flashes

Terrestrial gamma-ray flashes (TGFs) were first reported using data from the Burst and Transient Source Experiment (BATSE) onboard NASA's Compton Gamma-Ray Observatory (CGRO) in 1994.

The short duration (0.2 to 3.5 milliseconds) atmospheric bursts of gamma rays (i.e. very high energy photons) were initially thought to be caused by relativistic runaway electron avalanches acting on natural background radiation, or extensive cosmic-ray air showers - these theories a…; Tornadosplugin-autotooltip__plain plugin-autotooltip_bigTornados

Descriptions of the atmospheric mechanisms which cause tornados to form ('tornadogenesis') are currently unclear. Similar problems exist with full explanations of dust-devils, waterspouts, landspouts and hurricanes.

Currently available computer models (such as VORTEX2) are only partially successful. Tornados usually from in severe storms known as 'supercells' - but the specific conditions which lead to tornado formation - or non-formation - are unknown.; Water - its originplugin-autotooltip__plain plugin-autotooltip_bigWater - its origin

One obvious difference between Earth and other planets in the Solar System is that it's 70% covered in liquid water. There are at least five major (and very different) theories proposing the origins of such a large volume of water (estimated at around 1.3 billion cubic kilometres).; Medicinal drug pollution in waterwaysplugin-autotooltip__plain plugin-autotooltip_bigMedicinal drug pollution in waterways

"Despite having known for almost two decades that pharmaceuticals are commonly found in aquatic environments (Kolpin et al. 2002), we are only beginning to understand the potential implications of these synthetic chemicals on aquatic organisms and ecosystem processes."; Diquis spheresplugin-autotooltip__plain plugin-autotooltip_bigDiquis spheres

In the 1930's workers from the United Fruit Company, who were clearing land in the Diquís Valley Delta region of Costa Rica, began finding large numbers of almost perfectly round stone spheres.

The spheres, which range from a few kilograms up to around 16 tonnes, are accurately made, presumably by chipping.; Liubo (ancient Chinese board game)plugin-autotooltip__plain plugin-autotooltip_bigLiubo (ancient Chinese board game)

Liubo 六博 is an ancient Chinese board game for two players.

Historians have determined that it was invented no later than the middle of the 1st millennium BCE - being popular during the Han dynasty (202 BCE – 220 CE).; Mustatilsplugin-autotooltip__plain plugin-autotooltip_bigMustatils

Mustatils are ancient (c. 5,300 - 5,000 BC) archeological structures found in large numbers (more than 1,000) across present-day Saudi Arabia and Jordan, in an area of more than 200,000 km².

Their name comes from the Arabic word for 'rectangle', which is their most common shape. They have also been found in; Nazca linesplugin-autotooltip__plain plugin-autotooltip_bigNazca lines

The Nazca Lines are an extensive, man-made set of 'geoglyphs' (earth signs) created in the Nazca Desert in southern Peru. The majority are in the form of simple straight lines, but there are also depictions of animals, plants, tools. and geometric forms etc.; Perforated batonsplugin-autotooltip__plain plugin-autotooltip_bigPerforated batons

"Perforated" or "Pierced Batons" (in French "bâton percé") are man-made historical artefacts formed from deer antlers. They have been found widely distributed across Europe, and range in age from around 23K to 12K years old. They are typically 'Y' or 'T' shaped, and all feature a carefully drilled circular hole.; The 'Plain of Jars'plugin-autotooltip__plain plugin-autotooltip_bigThe 'Plain of Jars'

The UNESCO World Heritage listed Plain of Jars is an area of current-day Laos which features more than 2,000 large stone jars (weighing up to 20 tonnes) dating from around 500 BCE to 500 CE.

"Northern Laos is home to one of Southeast Asia’s most enigmatic archaeological cultures. The megalithic jar sites of Laos comprise one to three-metre-tall carved stone jars dotted across the landscape, appearing alone or in groups of up to several hundred. The majority of these sites …; Shoe concealmentplugin-autotooltip__plain plugin-autotooltip_bigShoe concealment

Builders and archaeologists sometimes comes across old shoes (usually just one of a pair) which have been deliberately hidden in inaccessible places in the fabric of old buildings. Under floorboards, behind bricked-up fireplaces etc etc.; Basque language originsplugin-autotooltip__plain plugin-autotooltip_bigBasque language origins

The Basque language - which is spoken in the Basque Country, and also extending over a strip along eastern areas of the Bay of Biscay in Spain and France - is classified as a language isolate. There are currently around 800,000 speakers.; Dispilio tabletplugin-autotooltip__plain plugin-autotooltip_bigDispilio tablet

"The Dispilio tablet is a wooden tablet bearing inscribed markings, unearthed during George Hourmouziadis's excavations of Dispilio in Greece, and carbon 14-dated to 5202 (± 123) BC. It was discovered in 1993 in a Neolithic lakeshore settlement that occupied an artificial island near the modern village of Dispilio on Lake Kastoria in Kastoria, Western Macedonia, Greece.; The Voynich Manuscriptplugin-autotooltip__plain plugin-autotooltip_bigThe Voynich Manuscript

"The Voynich manuscript is an illustrated codex hand-written in an unknown writing system. The vellum on which it is written has been carbon-dated to the early 15th century (1404–1438)

[...] The Voynich manuscript has been studied by many professional and amateur cryptographers, including American and British codebreakers from both World War I and World War II.[19] No one has yet succeeded in deciphering the text, and it has become a famous case in the history of crypto…; Floral longevityplugin-autotooltip__plain plugin-autotooltip_bigFloral longevity

Flowers allowed to remain on the parent plant tend to last anywhere between 1 to 30 days* in terms of their pollination period. This large variation (x30) in longevity remains unexplained.

"Floral longevity, the length of time a flower remains open and functional, is an important trait in pollination biology. Optimal floral longevities balance flowering costs against the rate of pollen export and receipt."; Gravity sensing in plantsplugin-autotooltip__plain plugin-autotooltip_bigGravity sensing in plants

Specialist cells (Statocytes) in plants are able to sense gravity. Thus shooting tips grow upwards, against the Earth's gravitational field, while roots grow downwards. Statocytes are located in the starch parenchyma cells near vascular tissues in the shoots, and in the columella in the caps of the roots.; Hybrid vigourplugin-autotooltip__plain plugin-autotooltip_bigHybrid vigour

"The question of why certain progeny of crosses or hybrids between unrelated individual plants and animals show greater vigor, productivity, disease resistance, viability and fertility, or Darwinian fitness as opposed to the progeny of close relatives has fascinated humans for millennia."; Nuclear movement in plantsplugin-autotooltip__plain plugin-autotooltip_bigNuclear movement in plants

It's been known for many decades that the nuclei of animal cells are constantly in motion within the cell. Less well known, and less well studied, is the fact that the nuclei of plant cells are also often in constant motion.; Foliar nictinastyplugin-autotooltip__plain plugin-autotooltip_bigFoliar nictinasty

Foliar Nictinasty (FN) is the tendency for (some) plants to open their leaves during daylight hours and close them at night - tightly following the day/night cycle.

This process has been observed and debated for at least 2,000 years. In 1729; Oxygen Evolving Process (EVP)plugin-autotooltip__plain plugin-autotooltip_bigOxygen Evolving Process (EVP)

"Photosynthetic oxygen evolution is the fundamental process by which oxygen is generated in earth's biosphere. The reaction is part of the light-dependent reactions of photosynthesis in cyanobacteria and the chloroplasts of green algae and plants. It utilizes the energy of light to split a water molecule into its protons and electrons for photosynthesis. Free oxygen, generated as a by-product of this reaction, is released into the atmosphere.; Photosynthesisplugin-autotooltip__plain plugin-autotooltip_bigPhotosynthesis

"Photosynthetic water splitting (or oxygen evolution) is one of the most important reactions on the planet, since it is the source of nearly all the atmosphere's oxygen [...] The mechanism of water oxidation is still not fully elucidated,; Electrical activity in plantsplugin-autotooltip__plain plugin-autotooltip_bigElectrical activity in plants

Electrical signals within plant tissue have been studied since the 1800s. Charles Darwin was interested in possible electrical signals in the Venus Flytrap mechanism (which is still not completely understood). In the 1920s Jagadish Chandra Bose investigated what he called; Movement and proximity sensing in plantsplugin-autotooltip__plain plugin-autotooltip_bigMovement and proximity sensing in plants

Plant movements have been scientifically investigated since the time of Charles Darwin, who researched the 'Movements and Habits of Climbing Plants'. (ref)

Recently, various experimental studies have suggested not only that many plants have a form of 'proprioception' (i.e. an 'awareness' of the physical position of their own tissues -; Pollen Tubesplugin-autotooltip__plain plugin-autotooltip_bigPollen Tubes

"A pollen tube is a tubular structure produced by the male gametophyte of seed plants when it germinates. Pollen tube elongation is an integral stage in the plant life cycle. The pollen tube acts as a conduit to transport the male gamete cells from the pollen grain - either from the stigma (in flowering plants) to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms."; Stromulesplugin-autotooltip__plain plugin-autotooltip_bigStromules

"A stromule is a microscopic structure found in plant cells. Stromules (stroma-filled tubules) are highly dynamic structures extending from the surface of all plastid types, including proplastids, chloroplasts, etioplasts, leucoplasts, amyloplasts, and chromoplasts."; Thermogenic plantsplugin-autotooltip__plain plugin-autotooltip_bigThermogenic plants

More than 900 plant species are known to be able to internally heat themselves. A famous example is the Skunk Cabbage, Symplocarpus foetidus, which is capable of maintaining an internal temperature of around 20 °C even when the ambient temperature drops as low as 0 °C.; Venus Flytrap mechanismplugin-autotooltip__plain plugin-autotooltip_bigVenus Flytrap mechanism

The Venus Flytrap (Dionaea muscipula) is a well-known carnivorous plant native to the sub-tropical wetlands of the US.

The 'trap' structure snaps shut when insects or spiders repeatedly touch specialised 'trigger hairs' on the trap's upper surface.; Cellular vaultsplugin-autotooltip__plain plugin-autotooltip_bigCellular vaults

Vaults are microscopic structures found in nearly all cells which have a nucleus. They were first seen in 1986 using electron microscope 'negative staining' techniques.(ref.)

They are highly regular in structure, made of specialsed proteins, and with a strict 36-fold symmetry (; Centrioles (cell biology)plugin-autotooltip__plain plugin-autotooltip_bigCentrioles (cell biology)

Centrioles (a.k.a. Basal bodies) are found in many* cells that have a nucleus. They were discovered when advances in microscopes made it possible to look closely at the inner structure of living cells.

They feature a central cylinder or barrel-like structure, about 450 nm high and 250 nm in diameter, with various 'appendages' attached in a nine-fold symmetrical pattern. It's known that the structure features more than 100 different proteins.; The Nuclear Matrixplugin-autotooltip__plain plugin-autotooltip_bigThe Nuclear Matrix

First described in 1948, the Nuclear Matrix refers to a network of fibres found inside the nucleus of all animal, plant, fungi and bacterial (etc.) cells, It has also been termed the “Nuclear-Scaffold” or "NuMat".

The function of the matrix is disputed. Some theorists suggest that it's an active structure involved in biochemical and genetic transport - as it contains proteins, chaperones, DNA/RNA-binding proteins, chromatin remodeling and transcription factors (Source :; Flowering plants evolutionplugin-autotooltip__plain plugin-autotooltip_bigFlowering plants evolution

The evolutionary pathways that produced the flowering plants (the Angiosperms) have been studied for at least 140 years.

The flowering plants appear very suddenly (geologically speaking) in the fossil record, at around 100 million years ago. Before that, all known plants were; Hand and digits evolutionplugin-autotooltip__plain plugin-autotooltip_bigHand and digits evolution

"How the hand and digits originated from fish fins during the Devonian fin-to-limb transition remains unsolved. Controversy in this conundrum stems from the scarcity of ontogenetic data from extant lobe-finned fishes."

Source :; Multicellular organismsplugin-autotooltip__plain plugin-autotooltip_bigMulticellular organisms

It's generally assumed that during the evolution of lifeforms, there must have been some stage when single cells (unicelluar organisms) grouped together to form multicellular life.

There are at least nine different major theories regarding how (and why) this might have happened. See:; Evolution of neuronsplugin-autotooltip__plain plugin-autotooltip_bigEvolution of neurons

"Neurons are highly specialized cells equipped with a sophisticated molecular machinery for the reception, integration, conduction and distribution of information. The evolutionary origin of neurons remains unsolved. How did novel and pre-existing proteins assemble into the complex machinery of the synapse and of the apparatus conducting current along the neuron?"; Circular RNAplugin-autotooltip__plain plugin-autotooltip_bigCircular RNA

"Thought to result from splicing errors, circular RNA species possess no known function." Source RNA Journal 2013.

RNA usually occurs in strands, but can also form circular loops. It's predominantly found in a cell's cytoplasm - i.e. outside the cell nucleus.; Endogenous Retrovirusesplugin-autotooltip__plain plugin-autotooltip_bigEndogenous Retroviruses

Endogenous retroviruses (ERVs) are viral elements found in the genome of vertebrates that closely resemble (and can be derived from) retroviruses. In humans (where they are known as HERVs) this 'rogue' DNA is believed to make up between 5 - 8% of the human genome.; Heritable primingplugin-autotooltip__plain plugin-autotooltip_bigHeritable priming

Heritable Priming is the name given to the process in which organisms are able to pass on stress-protection from the parent generation to the siblings.

The 'stress' can be physical (one of the original studies investigated how plants' lack of water can protect later generations from drought stress) or bacteriological / viral.; Appetite Regulationplugin-autotooltip__plain plugin-autotooltip_bigAppetite Regulation

Very extensive research, over many decades, has identified a number of biochemical routes that can influence appetite in humans.

For an overview, see: Mechanisms of Appetite Regulation Journal of Pediatric Gastroenterology and Nutrition 51():p S123-S124,

In particular, the so called 'hunger hormones'; Arm swinging (in human walking)plugin-autotooltip__plain plugin-autotooltip_bigArm swinging (in human walking)

"Apart from the question whether arm swing is actively controlled or merely passive, there seems to be no consensus on why humans swing their arms during gait (i.e. what the purpose of arm swing is, if it has a purpose at all).; Human birth defectsplugin-autotooltip__plain plugin-autotooltip_bigHuman birth defects

Birth defects - sometimes severe - occur at a rate of roughly 1 per 33 births worldwide. Which currently equates to nearly 8 million per year.

Of these, approximately 20% can be accounted for (genetic defects, smoking, viruses and bacteria, obesity, stress etc) the remaining 80% have unknown causes.; Contagious Yawningplugin-autotooltip__plain plugin-autotooltip_bigContagious Yawning

Most people have seen examples of Contagious Yawning in humans. If one person in a group yawns (or convincingly feigns a yawn) it's often quite hard for others to resist. Current estimates are that 40-60% of human yawns are 'contagious'.; Default Mode Network (brain area)plugin-autotooltip__plain plugin-autotooltip_bigDefault Mode Network (brain area)

The Default Mode Network (DMN) is a large-scale* brain area which was discovered during 'real-time' brain-scan experiments in the late 1990s.

The DMN was seen to decrease its activity during attention-demanding tasks, and then resume activity once the task was over.; Immune tolerance in pregnancyplugin-autotooltip__plain plugin-autotooltip_bigImmune tolerance in pregnancy

Why doesn't an expectant mother's immune system damage her growing baby - since it has 'foreign' DNA?

This fundamental phenomenon has yet to be fully explained.

"During pregnancy, the maternal immune system is exposed to a major challenge. The fetus expresses paternal alloantigens, yet it is not rejected.; Hair greying (canities)plugin-autotooltip__plain plugin-autotooltip_bigHair greying (canities)

"Hair greying (referred to during ageing as ‘canities’) is one of the earliest and most visible indicators of ageing in humans. The social significance of greying persists across cultures, geographical locations, and ethnicities, alongside a now-widespread interest in its reversal.; Human pheromonesplugin-autotooltip__plain plugin-autotooltip_bigHuman pheromones

Pheromones were defined in 1959 by Karlson and Luscher from the Max Planck Institute for Biochemistry in Munich, Germany, as “Substances which are secreted to the outside by an individual and received by a second individual of the same species, in which they release a specific reaction, for example, a definite behavior or a developmental process.; Infant Rockingplugin-autotooltip__plain plugin-autotooltip_bigInfant Rocking

"People tend to fall asleep when gently rocked or vibrated. Experimental studies have shown that rocking promotes sleep in humans and mice. However, the mechanisms underlying the phenomenon are not well understood."

Source : Cell Reports[Open Access]vol. 33, issue 9.; The Interstitiumplugin-autotooltip__plain plugin-autotooltip_bigThe Interstitium

In 2018, a research team from NYU School of Medicine published a paper in the journal Scientific Reports, entitled : Structure and Distribution of an Unrecognized Interstitium in Human Tissues.

The paper described what is now known as the Interstitium - a contiguous network of interconnected fluid-filled spaces below the skin's surface. It lines the digestive tract, lungs and urinary systems, as well as surrounding arteries, veins, and the; The Mesenteryplugin-autotooltip__plain plugin-autotooltip_bigThe Mesentery

"The mesentery is a continuous set of tissues which is formed by the double fold of peritoneum that attaches the intestines to the wall of the abdomen. ['..] It has been proposed for reclassification as an organ due to research at the University of Limerick in the 2010s"; Microbiome interactionsplugin-autotooltip__plain plugin-autotooltip_bigMicrobiome interactions

"The human gut harbors trillions of invisible microbial inhabitants, referred to as the microbiota, that collectively produce thousands of unique small molecules. The sources and biological functions of the vast majority of these molecules are unknown.; Microgravity Immune Suppressionplugin-autotooltip__plain plugin-autotooltip_bigMicrogravity Immune Suppression

"Spaceflight causes alterations in human immunity, a finding which has been well documented immediately following spaceflight. Limited in-flight studies have also confirmed that to some degree immunity is compromised; Neuromelaninplugin-autotooltip__plain plugin-autotooltip_bigNeuromelanin

"Neuromelanin (NM) is a dark insoluble polymer pigment produced in specific populations of catecholaminergic neurons in the brain. Humans have the largest amount of NM, which is present in lesser amounts in other primates, and totally absent in many other species.; Ovarian agingplugin-autotooltip__plain plugin-autotooltip_bigOvarian aging

As women age, they experience a decline in reproductive performance leading to menopause (average 51 ± 8 years). This decline is tied to a reduction in the number of ovarian follicles present in the ovaries. The events that lead to to the decline - i.e. ovarian aging - are unknown. The variability of aging could include environmental factors, lifestyle habits and/or genetic factors.; Oxyphil cellsplugin-autotooltip__plain plugin-autotooltip_bigOxyphil cells

Oxyphil cells are a specialised group of cells found in the ParaThyroid gland of humans (and some other mammals).

They're not present at birth, and their numbers increase with age. They also increase in patients with chronic kidney disease.; PFAS pollutionplugin-autotooltip__plain plugin-autotooltip_bigPFAS pollution

Perfluoroalkyl and polyfluoroalkyl substances ( PFAS ) are synthetic organofluorine chemical compounds which have multiple fluorine atoms attached to an alkyl chain. They have been commercially produced in vast quantities since the 1940s, and have applications in the manufacture of lubricants, water repellents, fire retardants etc etc.; Photic Sneezingplugin-autotooltip__plain plugin-autotooltip_bigPhotic Sneezing

"The photic sneeze reflex is a reflex condition that causes sneezing in response to numerous stimuli, such as looking at bright lights or periocular (surrounding the eyeball) injection. The condition affects 18–35% of the world's population"; Unknown protein-functionsplugin-autotooltip__plain plugin-autotooltip_bigUnknown protein-functions

The Human Genome Project was declared fully complete in 2022. It lists the entire genome for the human body. Genes 'code' for specific protein production within cells. Although many of the important proteins now have very well-cataloged lists of functions, many others are completely obscure. The number of these unknown proteins - many thousands of them - is currently estimated to be around 20% of the total.; Salsolinolplugin-autotooltip__plain plugin-autotooltip_bigSalsolinol

Salsolinol (SAL) is a dopamine-related compound first discovered in the 1970s. It was found in the urine of patients with Parkinson's, and was assumed to be a possible chemical marker for the disease. But only a few years later it was also found in healthy individuals - and subsequently in a wide range of foodstuffs, including bananas, cocoa and beer.; Salt and hypertensionplugin-autotooltip__plain plugin-autotooltip_bigSalt and hypertension

It's been known for several thousand years that an excess intake of common salt can have adverse effects on the cardiovascular system. (ref.)

Recent research has shown unequivocally that long-term high intakes of salt can cause a range of problems in otherwise healthy individuals. Dietary specialists worldwide have now come to an agreement that salt intake for adults should be no more than 5g. per day.; Sighingplugin-autotooltip__plain plugin-autotooltip_bigSighing

A sigh is defined as a kind of paralinguistic respiration in the form of a deep, audible, single exhalation of air out of the mouth or nose.

Sighing may have purely physiological triggers (see: Respiratory variability preceding and following sighs: A resetter hypothesis [ paywalled ] in: Biological Psychology, Volume 84, Issue 1, Pages 82-87), or may arise from negative emotion, i.e. from feelings such as dismay, dissatisfaction, boredom, or futility.; Spaceflight anemiaplugin-autotooltip__plain plugin-autotooltip_bigSpaceflight anemia

"Anemia in astronauts has been noted since the first space missions, but the mechanisms contributing to anemia in space flight have remained unclear."

Source : Nature Medicine volume 28, pages 59–62 (2022)"

Anomalies in the amount of hemoglobin degradation in astronauts (around 12% higher than normal) was first discovered in the 1980s. The degradation leads to anemia, and tends to take hold in the first 10 days or so of micro-gravity spaceflight. After-effects appear to be…; Sperm count declineplugin-autotooltip__plain plugin-autotooltip_bigSperm count decline

A 2017 report published in the journal Human Reproduction Update reviewed the results of over 2000 papers on sperm counts previously published (in English) between 1981 and 2013.

"This comprehensive meta-regression analysis reports a significant decline in sperm counts (as measured by SC and TSC) between 1973 and 2011, driven by a 50–60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand. Because of the significant public health…; Tasteplugin-autotooltip__plain plugin-autotooltip_bigTaste

Current theory lists five main taste receptor categories : sweetness, bitterness, sourness, saltiness, and umami. Source : Wikipedia

The physical mechanisms for detection of each of these main flavour types have been extensively investigated, and the corresponding tongue 'receptors' have (mostly) been identified.; Cell deathplugin-autotooltip__plain plugin-autotooltip_bigCell death

"Why living organisms inevitably die and what death even means in terms of physics and dynamical systems are still open questions despite the vast advances in molecular biology. Revealing how some cells die — not through biochemical processes but physics — would help to answer them."; CISS theoryplugin-autotooltip__plain plugin-autotooltip_bigCISS theory

The Chirality-Induced Spin Selectivity ( CISS ) effect was first discovered over two decades ago in the field of optical polarization. (ref.)

It was found that a fundamental quantum property of electrons - known as 'spin' - is strongly influenced by the 'chirality' i.e. 'handedness' of molecules.; Enzyme catalysisplugin-autotooltip__plain plugin-autotooltip_bigEnzyme catalysis

Almost all metabolic processes in living cells need enzyme catalysis in order to proceed at rates fast enough to sustain life. Although enzyme processes have been investigated for many decades, and more than 5000 have been identified, the extreme complexity of the biochemistry involved has meant that the way in which a particular enzyme operates can be far from clear.; Anemonefish Symbiosisplugin-autotooltip__plain plugin-autotooltip_bigAnemonefish Symbiosis

The Orange clownfish - Amphiprion percula - (also known as the Percula clownfish and Clown anemonefish), is widely-known as a popular aquarium fish. Like other clownfishes (also known as Anemonefishes), it often lives in close association with sea anemones.; Warning colourations (Aposematism)plugin-autotooltip__plain plugin-autotooltip_bigWarning colourations (Aposematism)

In the very earliest days of evolutionary theory (1860s), Charles Darwin and Alfred Russel Wallace noted apparent anomalies regarding the very prominent 'warning colours' displayed by a wide range of animals - a phenomenon later named; Assortative matingplugin-autotooltip__plain plugin-autotooltip_bigAssortative mating

Assortative mating refers to the tendency of (some) animals to mate with individuals that share similar traits. For example, having the same fur colour, or size. The effect is particularly strong in fishes, less so in birds. It also seems to apply, in some cases, to human populations.; Avian navigationplugin-autotooltip__plain plugin-autotooltip_bigAvian navigation

Many species of birds can very reliably navigate over large distances, even from places they have never been to, and return to their desired destination, often over hundreds or even thousands of kilometres.

Homing pigeons, for example, can very consistently find their way back to their adopted roosting place - even when they have been physically removed hundreds of kilometres away - and often without any knowledge of the removal route.; Avian soaringplugin-autotooltip__plain plugin-autotooltip_bigAvian soaring

Dozens of species of birds are expert at soaring (list). Using rising pockets of air which are slightly warmer than the surrounding air (called thermals) many species can travel hundreds - or even thousands - of kilometres with very little need to flap their wings. They tend to circle around within the thermal they've found, then, when they reach a high enough altitude, they glide down to the next available one. This is called 'dynamic soaring'.; Bee Colony Collapse Disorder [ CCD ]plugin-autotooltip__plain plugin-autotooltip_bigBee Colony Collapse Disorder [ CCD ]

"Colony collapse disorder (CCD) is the phenomenon that occurs when the majority of worker bees in a colony disappear and leave behind a queen, plenty of food and a few nurse bees to care for the remaining immature bees and the queen. While such disappearances have occurred throughout the history of apiculture, and were known by various names (disappearing disease, spring dwindle, May disease, autumn collapse, and fall dwindle disease), the syndrome was rena…; Bird flockingplugin-autotooltip__plain plugin-autotooltip_bigBird flocking

Many theories have been put forward to explain large-scale flocking and roosting behaviour in birds. But from an evolutionary point of view, all the theories have clear drawbacks.

Ideas include:

• Heat conservation - but in many roosts the birds maintain a significant distance from each other, allowing most of the accrued heat to radiate away.; Bird Unipedalismplugin-autotooltip__plain plugin-autotooltip_bigBird Unipedalism

Over 50 species of birds are known to habitually stand on one leg for long periods. The reasons why they do it are disputed :

"Flamingos are thought to stand on one leg to reduce muscle fatigue or heat loss. The muscle fatigue hypothesis assumes that standing for long periods requires sufficiently high levels of active contractile force that would fatigue muscle, necessitating alternating stance from one leg to the other. Conversely, the heat loss hypothesis assumes that the …; Tail wagging in domestic dogsplugin-autotooltip__plain plugin-autotooltip_bigTail wagging in domestic dogs

"Tail wagging is a conspicuous behaviour in domestic dogs (Canis familiaris). Despite how much meaning humans attribute to this display, its quantitative description and evolutionary history are rarely studied.

Source :; Catnipplugin-autotooltip__plain plugin-autotooltip_bigCatnip

The herbaceous plant Catnip (Nepeta cataria) dramatically affects several members of the cat family (Felidae) causing them to sniff, roll over, and undulate the skin on their back (amongst other things).

It generally only affects about 50% of cats, and the effects are profound - often lasting 15 minutes or so.; Nematocytes mechanismsplugin-autotooltip__plain plugin-autotooltip_bigNematocytes mechanisms

Nematocytes (a.k.a nematocysts, cnidocysts or cnidae) are the stinging cells found in jellyfish, hydra, sea anemones &etc.

"Though an enormous amount of work has been done on nematocysts, the problem of how they are discharged remains unsolved. There are really two separate problems. First, what is the natural stimulus which excites the cnidoblast; second, what is the physical mechanism by which the nematocyst itself discharges? There is more work on the mechanics of di…; Cooperative breedingplugin-autotooltip__plain plugin-autotooltip_bigCooperative breeding

In Cooperative breeding, individuals contribute towards the care and upbringing of offspring which are not their own. It's found in many species of birds, mammals, fish, and insects.*

The behaviour has puzzled evolutionary biologists for many decades, given that individuals apparently sacrifice some of their own breeding prospects in order to increase the potential of the species as a whole.; Coral spawningplugin-autotooltip__plain plugin-autotooltip_bigCoral spawning

"Broadcast spawning by corals is an amazingly precise temporal process. Every year, on just one or two evenings, many of the individuals of each broadcast spawning species release their gametes in a time window that is usually approximately 30 min long. With only a simple nerve net and no specialized light sensing organs to sense and interpret their local environment these simple cnidarians somehow manage to tell the time of year, the time of…; Diatom Structureplugin-autotooltip__plain plugin-autotooltip_bigDiatom Structure

"The silicified cell walls of diatoms have inspired the interest of researchers for several centuries, and our understanding of their properties and formation has developed in synch with the development of observational and analytical techniques. Over the past 20 years, approaches used to characterize the molecular components involved in cell wall silicification have evolved, and this has provided significant insights into fundamental aspects of silicification, and promises to…; Dinosaur extinctionplugin-autotooltip__plain plugin-autotooltip_bigDinosaur extinction

"The question why non-avian dinosaurs went extinct 66 million years ago (Ma) remains unresolved because of the coarseness of the fossil record. A sudden extinction caused by an asteroid is the most accepted hypothesis but it is debated whether dinosaurs were in decline or not before the impact.; Electric catfish self-immunityplugin-autotooltip__plain plugin-autotooltip_bigElectric catfish self-immunity

"For thousands of years, starting with detailed accounts from ancient Egypt, the African electric catfish (Malapteruridae) has been renowned for its ability to hunt and to defend itself with powerful electric shocks.; Firefly light display synchronyplugin-autotooltip__plain plugin-autotooltip_bigFirefly light display synchrony

There are many documented accounts (including video footage) of large groups of 'Fireflies' (typically beetles of the Lampyridae family) flashing their bio-luminescent lights in a synchronised display.

It's not known why they have developed the synchronised displays, and recent research is suggesting that the methods used to synchronise are less straightforward than was previously assumed.; Henry's pocketplugin-autotooltip__plain plugin-autotooltip_bigHenry's pocket

Henry's pocket - a.k.a. the Cutaneous Marginal Pouch - is a fold of skin found on the outer ear (pinnae) of many mammals. Weasels, bats and some cats and dogs have prominent versions of it. And there are vestigial traces in the human ear.; Hibernationplugin-autotooltip__plain plugin-autotooltip_bigHibernation

"Hibernation is an adaptive strategy characterized by a drastic suppression of metabolism, activity and body temperature that allows animals to survive during periods with little or no food availability; hibernation is widespread among mammals. Two types of mammalian hibernators exist: obligate hibernators, such as black bears and ground squirrels, hibernate every winter; Insect population declineplugin-autotooltip__plain plugin-autotooltip_bigInsect population decline

Various scientific studies have shown that the global terrestrial* insect population is in sharp decline.

The declines are primarily found in 'developed' nations. Estimates for the rate of decline vary wildly. One review study, which compiled the results of 166 previous surveys, suggested that it could be as high as 9% per decade (; Limb Regenerationplugin-autotooltip__plain plugin-autotooltip_bigLimb Regeneration

Many animals, notably salamanders, axolotls, octopuses and starfish (etc) are able to regrow limbs (and other body parts) which have been lost through accidents or disease. Although mammals can regrow various tissues - notably skin, liver and tail tips - there is no ability to regrow limbs etc.; Magnetoreceptionplugin-autotooltip__plain plugin-autotooltip_bigMagnetoreception

A number of animal species, including bacteria, arthropods, molluscs, fish, birds and mammals are known to be able to sense magnetic fields.

"Animals use geomagnetic fields for navigational cues, yet the sensory mechanism underlying magnetic perception remains poorly understood.; Monogamyplugin-autotooltip__plain plugin-autotooltip_bigMonogamy

As well as humans, many birds, fishes and mammals are broadly monogamous. ( examples here )

However, monogamy seems to contradict traditional evolutionary theory because it appears to severely limit the gene-pool available to breeding animals.

There are several theories to explain how it might have evolved. (See; Moths and light attractionplugin-autotooltip__plain plugin-autotooltip_bigMoths and light attraction

Many insects are quite dramatically attracted to artificial light sources. So called 'Phototaxis'.

Moths in particular are (famously) so drawn to light sources that they frequently get burnt in candle flames.

Moths are known to have a visual system that is extremely sensitive in low light conditions - presumably an advantage for nocturnal species. They are also known to migrate using moonlight and windspeed as navigational cues. But a precise, agreed, explanation as…; The muscle synergy hypothesisplugin-autotooltip__plain plugin-autotooltip_bigThe muscle synergy hypothesis

The Muscle Synergy Hypothesis refers to a concept used to attempt an explanation for animals' ability to carry out very complex movements involving accurate control of many different muscles at the same time.

In humans, for example, a movement commonly thought of as relatively straightforward - such as carrying a liquid-filled cup without spilling the contents - is in reality highly complex. The arm has many 'degrees of freedom', that's to say that the individual …; Naked mole-rat - cancer resistanceplugin-autotooltip__plain plugin-autotooltip_bigNaked mole-rat - cancer resistance

"Naked mole-rats (NMRs; Heterocephalus glaber) are highly adapted, eusocial rodents renowned for their extreme longevity and resistance to cancer. Because cancer has not been formally described in this species, NMRs have been increasingly utilized as an animal model in aging and cancer research."; Octopus camouflageplugin-autotooltip__plain plugin-autotooltip_bigOctopus camouflage

Many species of octopuses (and some other cephalopods) have extremely efficient mechanisms for camouflaging themselves against coloured backgrounds. They also use coloured patterns for communication and for repelling predators. The physical mechanisms for generating the colours in their skin is well understood (; Pearl formationplugin-autotooltip__plain plugin-autotooltip_bigPearl formation

Pearls are the only 'gems' produced by a living organism. Their formation process (either by natural means or through human intervention) is a response to an injury in an oyster's 'mantle' tissue, such as an intrusion by a foreign body, e.g. a sand grain etc.; Peto's paradoxplugin-autotooltip__plain plugin-autotooltip_bigPeto's paradox

Peto's Paradox was introduced by the UK epidemiologist Richard Peto in 1977. It is still generally considered unsolved.

Simply stated : All animal cells have the potential to turn cancerous. Large animals have many more cells, therefore larger animals should be subject to higher rates of cancer. But they're not. In mammals for example, the larger animals in general have broadly similar rates to the smaller ones.; Photoluminescence in animalsplugin-autotooltip__plain plugin-autotooltip_bigPhotoluminescence in animals

"Every year, more and more discoveries of photoluminescence in different mammal species are made. The more recent cases thus far have been in duck-billed platypus (Ornithorhyncus anatinus), New World squirrels (Glaucomys; Stony Coral Tissue Loss Diseaseplugin-autotooltip__plain plugin-autotooltip_bigStony Coral Tissue Loss Disease

Stony Coral Tissue Loss Disease (SCTLD) is a severe disease affecting corals. It was first noticed in 2014 around the Florida coast, and since then has spread to various other locations, especially in the Caribbean.; Tail Weaponisationplugin-autotooltip__plain plugin-autotooltip_bigTail Weaponisation

Weaponry, for the purpose of combat or predator defence, is one of the most widespread animal adaptations.

A 2018 paper in Proceedings of the Royal Society, Biological Sciences points out that tail weaponisation (flails, spikes, bats and clubs etc) which is very prevalent in the fossil record, is exceptionally rare in currently living animals.; Tonic Immobilityplugin-autotooltip__plain plugin-autotooltip_bigTonic Immobility

"Tonic Immobility (TI) is a reversible coma-like stasis inherent to a variety of terrestrial and aquatic taxa, including elasmobranchs [sharks] yet virtually nothing is known about its underlying neurological and physiological processes in any taxa."; Tropical colourfulnessplugin-autotooltip__plain plugin-autotooltip_bigTropical colourfulness

As far back as the 19th century, biologists pointed out an apparent anomaly in the extra 'colourfulness' of birds and insects in tropical regions.

The reasons for the differences remain unproven, but Alfred Wallace and others suggested that they might be due to the “luxuriant vegetation of the tropics” which acted as a natural camouflage all year round, whereas organisms in the North and South had to adapt their plumage to match the bare trees in winter.; Vitamin C deficitsplugin-autotooltip__plain plugin-autotooltip_bigVitamin C deficits

Humans, some non-human primates, guinea pigs, bats, capybara and some birds and fish have lost the ability to synthesize vitamin C - apparently due to an as-yet-unexplained gene mutation defect. Because vitamin C is required for a range of essential metabolic reactions, these animals can't maintain health over sustained periods without obtaining the vitamin by eating other organisms (or derived products) which; Whale Songplugin-autotooltip__plain plugin-autotooltip_bigWhale Song

Several species of whales - notably the male Humpback Whales (Megaptera novaeangliae) - engage in so-called 'singing' displays. (The songs were first noted by undersea microphone systems installed to detect the movements of submarines.)

"; White band (coral disease)plugin-autotooltip__plain plugin-autotooltip_bigWhite band (coral disease)

White Band Disease (WBD) is a rapidly spreading disease of coral - notably Elkhorn coral (Acropora palmata) and Staghorn coral (A. cervicornis).

It was first noted in the 1970s in the Caribbean, where it has now eradicated around 95% of the two coral species - with severe knock-on effects for other organisms which depend on them. It's also been found in the Red Sea, the Indo-Pacific region, Australia's Great Barrier Reef, and in Indonesia.; Auction optimizationplugin-autotooltip__plain plugin-autotooltip_bigAuction optimization

"A major difficulty in designing auctions is that valuations are private and bidders need to be incentivized to report their valuations truthfully. The goal is to learn an incentive compatible auction that maximizes revenue. In a seminal piece of work, Myerson resolved the optimal auction design problem when there is a; Benford's Lawplugin-autotooltip__plain plugin-autotooltip_bigBenford's Law

Benford's Law - also known as the Newcomb–Benford law, was originally stated by astronomer Simon Newcomb in 1881, and was subsequently re-stated by physicist Frank Benford in 1938.

Benford originally called his thesis 'The Law of Anomalous Numbers' (; Cramér's conjectureplugin-autotooltip__plain plugin-autotooltip_bigCramér's conjecture

Cramér's conjecture is stated as :

$${\displaystyle \limsup _{n\rightarrow \infty }{\frac {p_{n+1}-p_{n}}{(\log p_{n})^{2}}}=1,}$$

It was provided by the Swedish mathematician Harald Cramér in 1936, and provides a formula related to estimating the size of the spaces between consecutive prime numbers.

To date, there is no formal proof regarding whether or not the formula holds for all possible groups of prime numbers.; Fractalsplugin-autotooltip__plain plugin-autotooltip_bigFractals

unknowable

The word 'Fractal' was coined in 1975 by the mathematician Benoît Mandelbrot - but the study of self-repeating mathematical systems dates back several centuries.

Mandelbrot provided a definition of a fractal as : "A rough or fragmented geometric shape that can be split into parts, each of which is (at least approximately) a reduced-size copy of the whole".; Hadamard conjectureplugin-autotooltip__plain plugin-autotooltip_bigHadamard conjecture

"A Hadamard matrix is a type of square (-1,1)-matrix invented by Sylvester (1867) under the name of anallagmatic pavement, 26 years before Hadamard (1893) considered them. In a Hadamard matrix, placing any two columns or rows side by side gives half the adjacent cells the same sign and half the other sign. When viewed as pavements, cells with 1s are colored black and those with; The Kelvin problem (3-D packing)plugin-autotooltip__plain plugin-autotooltip_bigThe Kelvin problem (3-D packing)

In 2 dimensions, the most efficient packing mechanism is an array of hexagons - a honeycomb. In 1887, William Thomson (Lord Kelvin) asked the question 'What is the most efficient 3-D packing system?"

See (the original paper) :; The Moving Sofa problemplugin-autotooltip__plain plugin-autotooltip_bigThe Moving Sofa problem

"The moving sofa problem is a well-known unsolved problem in geometry, ﬁrst posed by Leo Moser in 1966, It asks: "What is the planar shape of maximal area that can be moved around a right-angled corner in a hallway of unit width?"; Self-Organized Criticalityplugin-autotooltip__plain plugin-autotooltip_bigSelf-Organized Criticality

The term Self-Organized Criticality (SOC) was introduced in a 1987 paper for Physical Review Letters. The groundbreaking research by Per Bak, Chao Tang and Kurt Wiesenfeld (now known as 'BTW') described how complex systems can feature 'critical' points in their development which can lead to sudden, dramatic changes (phase transitions).; The Scholz conjectureplugin-autotooltip__plain plugin-autotooltip_bigThe Scholz conjecture

The Scholz Conjecture relates the shortest length of an addition chain of Mersene numbers (ref.) to the shortest length of addition chains producing their exponents.

Stated formally as :

l(2n − 1) ≤ n − 1 + l(n),

where l(n; The square peg problemplugin-autotooltip__plain plugin-autotooltip_bigThe square peg problem

The Square Peg Problem (a.k.a. the Inscribed Square Problem and the Toeplitz' Conjecture) is a geometry problem proposed by German mathematician Otto Toeplitz in 1911.

It can be stated as :

"Does every plane simple closed curve contain all four vertices of some square?"; Achenbach syndromeplugin-autotooltip__plain plugin-autotooltip_bigAchenbach syndrome

Achenbach syndrome (a.k.a. paroxysmal finger hematoma and ‘blue finger’ syndrome ) is a benign condition which features spontaneous episodic pain and swelling in the joints of one or more fingers, along with the subsequent appearance of a bruise on the palm side of the affected finger joints.; Acneplugin-autotooltip__plain plugin-autotooltip_bigAcne

Acne is an extremely common skin condition which mainly affects the adolescent population (currently estimated at over 90%).

Despite very intensive research over many decades, a detailed explanation of what triggers and maintains the condition is still lacking.; Acrochorda (skin tags)plugin-autotooltip__plain plugin-autotooltip_bigAcrochorda (skin tags)

"Acrochordons are 1 mm to 1 cm (rarely giant sized) papules that may or may not have stems. Their color ranges from skin color to dark brown. Although acrochordon development has been associated type 2 diabetes mellitus (DM), glucose intolerance, hyperinsulinemia, obesity, pregnancy, acromegaly, aging, colonic polyps and genetic predisposition,; Alcohol and body weightplugin-autotooltip__plain plugin-autotooltip_bigAlcohol and body weight

Despite research over several decades - some involving more than 100,000 subjects - it's still unknown whether alcohol can (in general) cause body-weight gain.

Although alcohol is caloric - at around 7 calories per gram - it also increases metabolic rate - which, in effect 'burns' energy more quickly.; Apollo Syndromeplugin-autotooltip__plain plugin-autotooltip_bigApollo Syndrome

A 2016 study into cardiovascular disease (CVD) amongst members of the NASA Apollo missions found that the CVD mortality rate in Apollo lunar astronauts was 4–5 times higher than in non-flight and Low Earth Orbit astronauts.

"[...; Auto-immune disease + allergy increaseplugin-autotooltip__plain plugin-autotooltip_bigAuto-immune disease + allergy increase

"Since the 1950s, rates of multiple sclerosis , Crohn's disease, type 1 diabetes, and asthmahave soared by 300% or more. Similar graphs depict concurrent spikes in hay fever and food allergies." [our hyperlinks]

Source : Proc Natl Acad Sci U S A. 114(7): 1433–1436. "

This huge increase in auto-immune diseases and; Lower-back painplugin-autotooltip__plain plugin-autotooltip_bigLower-back pain

Around two thirds of humanity experience severe and persistent lower-back pain at some stage in their lives. It's the second most common reason (after respiratory illness) for visits to doctors, and one of the leading reasons for absence from work activities.; Brachioradial pruritus (BRP)plugin-autotooltip__plain plugin-autotooltip_bigBrachioradial pruritus (BRP)

"Brachioradial pruritus (BRP) has characteristic symptoms described by patients as itching with special characteristics such as tingling, burning and stinging. The characteristic locations are the dorsal aspects of the forearms and lateral aspects of the upper arms. There are few physical findings, and histological changes are sparse."; Calpainopathyplugin-autotooltip__plain plugin-autotooltip_bigCalpainopathy

Calpainopathy (a.k.a. LGMDR1) is the most common type of autosomal recessive limb-girdle muscular dystrophy (LGMD) It affects the muscles of the hip girdle and shoulder girdle.

Symptoms usually appear between the ages of 8 and 15. In severe cases, patients lose the ability to walk 10 - 20 years after symptoms first show.; Catamenial pneumothoraxplugin-autotooltip__plain plugin-autotooltip_bigCatamenial pneumothorax

Catamenial pneumothorax is an abnormal build-up of air/gas in the pleural space between the lung and the chest wall - specifically within 72 hours before or after the onset of a menstrual cycle. It was first described in 1958.; Cluster headacheplugin-autotooltip__plain plugin-autotooltip_bigCluster headache

"Cluster headache (CH) always involves pain that is one sided (although it can switch sides) and the main defining feature is the association with one or more of the 'cranial autonomic' features normally described as follows: • Reddening and tearing of the eye • A runny or blocked nostril • Droopy eyelid • Constriction of the pupil • Flushing and facial sweating; Coronary vasospasmplugin-autotooltip__plain plugin-autotooltip_bigCoronary vasospasm

Coronary vasospasm or Coronary Artery Spasm is a condition in which the arteries which supply the heart spontaneously constrict - leading to a lack of oxygen and a type of angina (chest pain) called Vasospastic angina or Prinzmetal angina; Cushing's diseaseplugin-autotooltip__plain plugin-autotooltip_bigCushing's disease

Cushing's disease, (a.k.a Cushing's syndrome and hypercortisolism ) is a rare, life-threatening, hormonal imbalance disorder.

"Cushing's syndrome, also called hypercortisolism, is a rare endocrine disorder caused by chronic exposure of the body's tissues to excess levels of cortisol - a hormone naturally produced by the adrenal gland. Exposure to too much cortisol can occur from long-term use of synthetic glucocorticoid hormones to treat inflammatory illnesses. Pituitary ade…; CVID (immune deficiency)plugin-autotooltip__plain plugin-autotooltip_bigCVID (immune deficiency)

Common variable immunodeficiency (CVID) is the name for a group of immune system disorders characterised by recurrent infections and low antibody levels,

Patients with CVID have chronic tiredness and, due to their malfunctioning immune system, are susceptible to a very wide range of infections, which can in turn lead to more serious complications;.; Diffuse panbronchiolitis (DPB)plugin-autotooltip__plain plugin-autotooltip_bigDiffuse panbronchiolitis (DPB)

Diffuse panbronchiolitis is a severe, progressive form of bronchiolitis, an inflammatory condition principally affecting the bronchioles (small air passages in the lungs).

It was first described in the 1960s in Japan, where it affects around 1 in 10,000 people. It causes wheezing and difficulties in breathing. If left untreated it's usually fatal. Treatment with modern antibiotics can greatly improve the survival rate (90%) - but currently there is no permanent '…; DISHplugin-autotooltip__plain plugin-autotooltip_bigDISH

Diffuse Idiopathic Skeletal Hyperostosis, or DISH (a.k.a. Forestier's disease) was first described over 100 years ago, It affects from 2.5% to 10% of people over the age of 70.

It causes inflammation, and bone overgrowth, at the sites where tendons are attached to bones. It typically affects the spinal vertebrae, but can also affect any other bone, e.g. the neck, shoulders, ribs, hips, pelvis, knees, ankles, and hands. where it leads to stiffness and painful movements.; Exercise-Induced Asthma (EIA)plugin-autotooltip__plain plugin-autotooltip_bigExercise-Induced Asthma (EIA)

Exercise Induced Asthma, or EIA (also known as Exercise-Induced Bronchoconstriction, EIB) is a form of Asthma (constriction of the airways) which is triggered by strong exercise. It was first reported in 1989.

It's prevalent amongst professional athletes at a far higher level than the general population. For example, some studies have put the prevalence as high as 45% for cyclists and 55% for skiers and skaters,; Endometriosisplugin-autotooltip__plain plugin-autotooltip_bigEndometriosis

"Endometriosis is a condition in which cells similar to those in the endometrium, the layer of tissue that normally covers the inside of the uterus, grow outside the uterus. Most often this is on the ovaries, fallopian tubes, and tissue around the uterus and ovaries; however, in rare cases it may also occur in other parts of the body."; Exercise-related Transient Abdominal Pain (a.k.a. 'Stitch')plugin-autotooltip__plain plugin-autotooltip_bigExercise-related Transient Abdominal Pain (a.k.a. 'Stitch')

ETAP - a.k.a. Stich, Side-ache, Side-stich &etc - is an extremely common lateral abdominal pain triggered by exercise - especially running.

It can be severe enough to cause athletes to drop out of races etc.; Fibromuscular dysplasiaplugin-autotooltip__plain plugin-autotooltip_bigFibromuscular dysplasia

"Fibromuscular dysplasia (also known as FMD) is a medical condition characterized by abnormal cell growth in the walls of arteries of the body."

Source : Circulation, Volume 125, Number 18"

It can affect any medium-sized artery in the body, and was first described in 1938. The arteries tend to form 'beads' rather than having the normal smooth walls. The beading can eventually lead to arterial blockages and leaks.; Flicker vertigoplugin-autotooltip__plain plugin-autotooltip_bigFlicker vertigo

Flicker vertigo ( also known as Flicker Illness and the Bucha Effect ) is a neurological condition which involves feelings of vertigo and nausea during exposure to flickering light sources. The troublesome flicker rate is normally in the range of 1 Hz to 30 Hz, As might be expected, the brighter the light, the stronger the effect.; Fox-Fordyce diseaseplugin-autotooltip__plain plugin-autotooltip_bigFox-Fordyce disease

Fox-Fordyce disease (FFD) is a rare inflammatory disorder that affects the apocrine sweat glands. The glands become blocked, leading to an inability to sweat in the affected areas, and intense itching.

It mostly affects women in the 13–35 age-group. It's generally thought that the syndrome might be caused by a hormonal imbalance of some kind, but the exact cause is unknown.; 'Frozen shoulder'plugin-autotooltip__plain plugin-autotooltip_big'Frozen shoulder'

Frozen Shoulder ( technical name : Adhesive capsulitis ) is a condition which causes severe pain and restricted movement of the shoulder joint. The pain is caused by abnormalities and hardening of the collagen in the tissues of the shoulder capsule joint.; Good's syndromeplugin-autotooltip__plain plugin-autotooltip_bigGood's syndrome

Good's Syndrome (a.k.a. Thymoma with immunodeficiency) was first described in 1955. Patients develop a thymoma (tumour of the thymus) and have greatly reduced antibody efficiency, which leads to increased susceptibility to bacterial, viral, and fungal infections.; Hepatitis E in pregnancyplugin-autotooltip__plain plugin-autotooltip_bigHepatitis E in pregnancy

Hepatitis E is a severe, acute disease caused by the Hepatitis E Virus (HEV). It can lead to severe liver damage. In most patients, however, it normally 'self resolves' (there is no specific effective treatment). It's widespread across the world, and is currently estimated to be responsible for around 77,000 deaths per year.; Histamine intoleranceplugin-autotooltip__plain plugin-autotooltip_bigHistamine intolerance

Histamine is an important naturally-occurring neuro-transmitter compound and 'local hormone' involved in mammalian gut regulation, immune responses and many other vital processes.

Histamine levels are finely balanced, and variations have dramatic effects on a range of bodily processes. Because the compound is also found in a range of foodstuffs (cheese, fish etc.) it has been suggested that some people may be prone to developing excess histamine levels if their digestive …; Influenza seasonalityplugin-autotooltip__plain plugin-autotooltip_bigInfluenza seasonality

The incidence of Influenza ('flu) is tightly linked to the seasons. In temperate climates the disease exists at low levels during the warmer Summer months, and then dramatically peaks during the Winter.

The reasons for this 'seasonality' have been examined and discussed at length for more than a century.; Kimura diseaseplugin-autotooltip__plain plugin-autotooltip_bigKimura disease

"Kimura disease is a benign rare chronic inflammatory disorder of unknown etiology that involves the lymph nodes and subcutaneous tissue of the head and neck regions. Elevated serum immunoglobulin E levels and peripheral blood eosinophilia are also common. This disease is most common in middle-aged Asian men. Although the etiology is unknown, it most probably represents an aberrant chronic immune response."; Kyrle diseaseplugin-autotooltip__plain plugin-autotooltip_bigKyrle disease

Kyrle disease is a relatively rare 'perforating' skin condition which leads to the formation of multiple large (up to 1.5cm) skin papules that have central keratin plugs. It usually affects the legs, but can also erupt in other areas. It was first described in 1916. The cause is currently unknown.; Macular degenerationplugin-autotooltip__plain plugin-autotooltip_bigMacular degeneration

Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which results in blurred (or absent) vision in the centre of the visual field. It can affect one or both eyes.

It's characterised by a general degeneration of the eye's central photo-receptors (retina) and surrounding tissues. Some types develop over a number of years, others in a matter of weeks.; Mal de debarquementplugin-autotooltip__plain plugin-autotooltip_bigMal de debarquement

Mal de debarquement Syndrome (MdDS) is associated with Motion sickness (i.e. sickness caused by the movement of sea, air and land travel) except that it's experienced after the individual returns to the stability of dry land.

It's a persistent form of 'Land sickness' which many people experience for short periods after disembarking from a voyage.; Masked Hypertensionplugin-autotooltip__plain plugin-autotooltip_bigMasked Hypertension

"Ever since hypertension was first recognized as a risk factor for cardiovascular disease, it has been identified by measurements made in an office or clinic setting. However, it has been known for more than 50 years that in many individuals these readings tend to be higher than readings taken in other situations."; Microplastics and human health implicationsplugin-autotooltip__plain plugin-autotooltip_bigMicroplastics and human health implications

Note: Microplastic pollution is so widespread that it's now been found contaminating almost all multicellular lifeforms which have been tested. This article is only related to possible risks to human health.; Misophoniaplugin-autotooltip__plain plugin-autotooltip_bigMisophonia

Misphonia is a distressing neuro-behavioral syndrome which involves decreased tolerance for sounds of certain types. Example noises include breathing, chewing, swallowing, clicking sounds, keyboard tapping, finger tapping, clock ticking, windshield wipers etc.; Motion sicknessplugin-autotooltip__plain plugin-autotooltip_bigMotion sickness

Dizziness and nausea is frequently caused by unusual physical motion (or perceived motion) - e.g. air sickness, sea sickness, car sickness, VR simulation sickness etc etc.

There are three commonly-documented versions :

* Caused by motion that is felt but not seen; Musicogenic seizuresplugin-autotooltip__plain plugin-autotooltip_bigMusicogenic seizures

A Musicogenic Seizure is a rare medical condition featuring epileptic-like seizures after exposure to music.

The seizures can be immediate, or delayed by a few minutes after heaing music - occasionally hours.

The mainstream current viewpoint is that the condition may be associated with a strong emotional response to the music rather than the musical sounds themselves. And that these emotional responses somehow cause adverse bio-chemical and/or bio-electrical changes in th…; Multiple Myelomaplugin-autotooltip__plain plugin-autotooltip_bigMultiple Myeloma

"Multiple myeloma, also known as plasma cell myeloma, is a cancer of plasma cells, a type of white blood cell normally responsible for producing antibodies. Often, no symptoms are noticed initially. When advanced, bone pain, bleeding, frequent infections, and anemia may occur. Complications may include amyloidosis.; Non-celiac gluten sensitivity (NCGS)plugin-autotooltip__plain plugin-autotooltip_bigNon-celiac gluten sensitivity (NCGS)

Non-celiac gluten sensitivity (NCGS) is currently defined as : "a clinical entity induced by the ingestion of gluten leading to intestinal and/or extraintestinal symptoms that improve once the gluten-containing foodstuff is removed from the diet, and celiac disease and wheat allergy have been excluded".; Osteoarthritisplugin-autotooltip__plain plugin-autotooltip_bigOsteoarthritis

"Osteoarthritis (OA) is considered a complex multifactorial disease of weight-bearing joints, with extensive psychosocial impact. The etiology of primary OA remains unknown and the molecular and cellular mechanisms of OA initiation and progression are not fully elucidated.; Phantom painplugin-autotooltip__plain plugin-autotooltip_bigPhantom pain

Phantom Pain - also known as Phantom Limb Pain (PLP) - is pain felt in a body-part which has been surgically removed or lost due to injury.

For amputees and those who've suffered limb-loss accidents it's extremely common - over 80% experiencing it at some stage. It can be persistent over many years. The pain, which can be severe, seems to originate at the location of the now-absent amputated part, rather than at the so-called 'stump' of the limb. The condition is poorly understood…; Plantar fasciitisplugin-autotooltip__plain plugin-autotooltip_bigPlantar fasciitis

Plantar fasciitis or plantar heel pain is a painful disorder of the fascia of the heel and sole of the foot.

The pain typically starts gradually, especially after exercise, and can affect both feet (in about one-third of cases). It can be so severe as to make normal walking impossible. It's the most common cause of acquired sub-calcaneal heel pain in adults, and recovery can take several weeks; Rhinophymaplugin-autotooltip__plain plugin-autotooltip_bigRhinophyma

Rhinophyma (Greek “nose growth”) is a benign skin deformity characterized by tumorous growth leading to a large, bulbous, and erythematous (reddish) appearance of the nose.

At present its cause is classified as 'unknown' though it is often associated with; Spaceflight-associated neuro-ocular syndrome (SANS)plugin-autotooltip__plain plugin-autotooltip_bigSpaceflight-associated neuro-ocular syndrome (SANS)

Approximately 60% of the crew members of the International Space Station have reported altered visual acuity after long-duration exposure to micro-gravity.

"Astronauts on long-duration spaceflight missions may develop changes in ocular structure and function, which can persist for years after the return to normal gravity.; Scoliosisplugin-autotooltip__plain plugin-autotooltip_bigScoliosis

Scoliosis is the medical term for 3 dimensional spinal curvature. It's thought to affect as many as 35 million people worldwide. The risk of developing scoliosis is known to have a genetic component, but it can also be due to environmental factors and neuro-muscular diseases. In the majority of cases, however, the cause is unknown.; Tropical Ataxic Neuropathy (TAN)plugin-autotooltip__plain plugin-autotooltip_bigTropical Ataxic Neuropathy (TAN)

"Tropical ataxic neuropathy, which is prevalent in the tropics causes significant disability as well as increased mortality and remains an enigmatic disease with no effective treatment or cure, even a century after its identification.; Tardive dyskinesiaplugin-autotooltip__plain plugin-autotooltip_bigTardive dyskinesia

Tardive dyskinesia (TD) [ rough translation 'late onset faulty movements' ] is a condition featuring involuntary repetitive body movements, which are caused by the long-term use of some anti-psychotic medications such as Haloperidol; Tendon sheath tumorsplugin-autotooltip__plain plugin-autotooltip_bigTendon sheath tumors

There are several types of benign tumors which grow on the sheaths of tendons - usually involving the tendons of the hand, though others can be affected.

The most prevalent types are Giant Cell Tumors, and a less common sub-type called; Venous Thrombosisplugin-autotooltip__plain plugin-autotooltip_bigVenous Thrombosis

Venous Thrombosis - blood clots which from in veins (as opposed to arteries) - are relatively common and potentially very dangerous (e.g. DVT).

Although it's firmly established that three factors (hypercoagulability, hemodynamic changes and endothelial injury - collectively known as; Alcohol and ageingplugin-autotooltip__plain plugin-autotooltip_bigAlcohol and ageing

The length of an individual's 'telomeres' - buffer caps which mark the beginning and end of the DNA sequences of chromosomes - have been used as a measure of actual physical 'ageing' (as opposed to measurement in years). [ * see note below ]; Artificial sweetenersplugin-autotooltip__plain plugin-autotooltip_bigArtificial sweeteners

"Artificial sweetener consumption is widely believed to be an effective method to limit caloric intake and maintain glycemic control. However, there is no evidence from long-term prospective analyses that the consumption of artificial sweeteners result in benefits in terms of weight loss and glycemic control (Swithers 2013). In fact, accumulating evidence now points to the opposite; that such products may precipitate metabolic derangements in susceptible individuals (Nett…; Donepezilplugin-autotooltip__plain plugin-autotooltip_bigDonepezil

Donepezil is a prescription-only drug used to alleviate some of the symptoms of Alzheimer's disease. There are currently around 5 million prescriptions per year in the US alone. It's sold under the brand names of Aricept, Namzaric and others.

It's known that the drug is a centrally-acting inhibitor of enzymes called cholinesterases.; General Anaestheticsplugin-autotooltip__plain plugin-autotooltip_bigGeneral Anaesthetics

A general anaesthetic is a drug that brings about a reversible loss of consciousness.* [ see note below ]

In formal use since 1842 - the first public demonstration used Diethyl ether to carry out surgery. (Though it's likely that alcohol, another chemical classed as an anaesthetic, was previously used, extensively, for similar purposes).; Kavainplugin-autotooltip__plain plugin-autotooltip_bigKavain

Kavain is the active ingredient of extracts of Kava root ((Piper methysticum).

"For millennia, Pacific Islanders have been using the root of a native pepper plant called kava (Piper methysticum) to prepare a non-alcoholic psychoactive beverage, which is also called kava. Kava drinking is an integral component of the Pacific Islander culture, with kava playing roles as a sacred drug in religious rituals, a social lubricant at formal gatherings, and a medicine to induce relaxation and sl…; Levetiracetamplugin-autotooltip__plain plugin-autotooltip_bigLevetiracetam

Levetiracetam, sold under brand names of Keppra, Elepsia, Epictal, Lenerve, Levepsy, Torleva (and many others) is a prescription-only anticonvulsant medication forepilepsy. It is used for partial onset, myoclonic, or tonic-clonic seizures. It is taken by mouth as an immediate or extended release formulation. There are currently more than 6 million prescriptions per year in the US alone.; Lithium (treatment for bipolar disorder)plugin-autotooltip__plain plugin-autotooltip_bigLithium (treatment for bipolar disorder)

Lithium, normally in the form of lithium carbonate (Li2CO3) is widely recognised as the 'gold standard' prescribed drug for treating bipolar disorder, depression and mania.

In widespread use since the early 1970s, lithium carbonate was the first; Cranial Electrotherapy Stimulationplugin-autotooltip__plain plugin-autotooltip_bigCranial Electrotherapy Stimulation

Cranial Electrotherapy Stimulation (a.k.a. cranial-electro stimulation and transcranial electrotherapy) is the application of small electrical alternating currents (e.g.1mA) to the brain, externally, via electrodes on the scalp. It has been in use since the late 1700s.; Cold water swimmingplugin-autotooltip__plain plugin-autotooltip_bigCold water swimming

Cold water swimming is currently considered as a treatment for Major Depressive Disorder. Several studies have examined the possible benefits, but results are not clear, partly because of the problems in excluding placebo effects, and social / lifestyle changes.; Green teaplugin-autotooltip__plain plugin-autotooltip_bigGreen tea

A 2006 study, published in the Journal of the American Medical Association, found that :

"Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer."; Placebo effectplugin-autotooltip__plain plugin-autotooltip_bigPlacebo effect

Placebos are faux medications - typically lactose or microcrystalline cellulose - designed to act as inert, non-functional 'controls' in medical experiments. (There are also faux medical procedures, see section below)

From the beginnings of their use in research, experimenters had assumed that they could not possibly have any medical effect. But they are now being taken seriously as treatments, after it was discovered that totally inactive substances; Cash as a disease vectorplugin-autotooltip__plain plugin-autotooltip_bigCash as a disease vector

Note: This article is currently in the 'Proposed Content' section.

It has long been suspected that cash (banknotes and coins) might "[..] serve as a vector of disease, though researchers disagree over how easily diseases are transmitted this way."; Electro-culture (botany)plugin-autotooltip__plain plugin-autotooltip_bigElectro-culture (botany)

Note: This article is currently in the 'Proposed Content' section, for possible inclusion in the 'Botany' section

The idea of using electricity to encourage plant growth goes back at least as far as the mid-eighteenth century.; Antimatter and gravityplugin-autotooltip__plain plugin-autotooltip_bigAntimatter and gravity

resolved

The 'Resolved' category archives questions which have been answered since they were added to the site.

As of Sep. 2023, this entry is now moved to the 'Resolved' section.

A recent set of experiments at CERN, which created thousands of 'antihydrogen' atoms (anti-protons with orbiting positrons), and then 'dropped' them down a 3m high column, have proved for the first tiime that the anti-atoms; The 'Brain in a vat' problemplugin-autotooltip__plain plugin-autotooltip_bigThe 'Brain in a vat' problem

unfalsifiable

Philosophers have been puzzling over the 'Brain in a Vat' problem for several decades. The 'problem' comes down to arguments over whether it's possible (or not) to philosophically 'prove' that one (i.e. the observer) is not simply an isolated brain that is, in effect, imagining the entire world around it.; Causalityplugin-autotooltip__plain plugin-autotooltip_bigCausality

On a simple level, the 'laws' of 'cause and effect' seem to be straightforward and self-evident - if you drop a 'priceless' ceramic vase onto a concrete floor, it will very probably break. (ref.) But examined in greater detail, and on larger timescales, causality reveals many levels of uncertainty and vagueness.; Free willplugin-autotooltip__plain plugin-autotooltip_bigFree will

unknowable

Do we have free will?

"... much of the debate about free will centers around whether we human beings have it, yet virtually no one doubts that we will to do this and that. "

Source : Stanford Encyclopedia of Philosophy [open access]"

Most people feel that they definitely do have free will, but the more research is performed, the harder it gets (for theorists at least) to maintain certainty.; The Antimatter Problemplugin-autotooltip__plain plugin-autotooltip_bigThe Antimatter Problem

According to Big Bang Theory, matter and anti-matter should have been created in equal amounts at the 'beginning' of the Universe. And, in experiments with high-energy particle accelerators, that is exactly what happens. Baryons (i.e. 'heavy' particles such as neutrons, protons, and their constituent quarks) and their anti-particle equivalents (anti-baryons) are created in equal numbers.; Chondrulesplugin-autotooltip__plain plugin-autotooltip_bigChondrules

Chondrules are the oldest known objects in the Solar System. They are small, generally are 0.1 to 1 mm in diameter. (Chondrules outside of this range have been observed, but are rare.) They are spherical rock-based granules that make up around 60-80% of a typical meteorite. They are usually formed from olivine and/or pyroxene, sometimes with smaller amounts of glass, iron and nickel.; Conformal cyclic cosmologyplugin-autotooltip__plain plugin-autotooltip_bigConformal cyclic cosmology

unknowable

Conformal Cyclic Cosmology (CCC) is a concept proposed in 2006 by the Nobel Prize winning cosmologist Professor Roger Penrose. It attempts to resolve a paradox associated with (standard) Big Bang theory.

"The issue arises from one of the most fundamental principles of physics: the; Dark Energyplugin-autotooltip__plain plugin-autotooltip_bigDark Energy

"The observational results of the latest 15 to 20 years have established a standard model for the cosmology which has some amazing consequences. A mysterious entity, the dark energy, has been confirmed as the dominant component of the Universe, and is also responsible for its accelerated expansion.; Galaxy mass anomaliesplugin-autotooltip__plain plugin-autotooltip_bigGalaxy mass anomalies

The gravitational pull of the combined masses of all the component stars and planets in a spiral galaxy must fall-off away from the centre, simply because there are less of them than in the tightly packed centre. So, before the 1970s, it had been assumed that stars which were further away from the centre of the galaxy would be rotating (around the central axis of the galaxy) at much slower speeds than those towards the centre.; Gamma-ray burstsplugin-autotooltip__plain plugin-autotooltip_bigGamma-ray bursts

Gamma-Ray Bursts (GRBs) were first discovered by satellites originally intended to scan for nuclear weapon detonations.They range from bursts of ten milliseconds to several hours, and also have differing energy levels. They are generally unexplained.; Jupiter's coreplugin-autotooltip__plain plugin-autotooltip_bigJupiter's core

Until 2017, astronomers had assumed that the 'core' of the planet Jupiter would be dense, comparatively small ( compared with the planet's diameter ), and would be composed of rock and ices, possibly surrounded by a layer of 'metallic' hydrogen under extreme pressure.; Lunar waterplugin-autotooltip__plain plugin-autotooltip_bigLunar water

A large number of experimental studies have confirmed that water (as ice) is present in multiple locations on the Moon. A 2010 study from NASA estimated that there are at least 600 million metric tonnes of ice around the Moon's North pole alone. (; Solar 'dynamo'plugin-autotooltip__plain plugin-autotooltip_bigSolar 'dynamo'

"Explaining the origin of the Sun’s magnetic field is the fundamental problem of solar magnetohydrodynamics (MHD). This dynamic magnetic field is responsible for all solar magnetic phenomena, such as solar flares, coronal mass ejections and the solar wind, and also heats the solar corona to extremely high temperatures. These phenomena all have important terrestrial consequences, causing severe magnetic storms and major disruption to satellites, as well as having a possible impac…; Solar spiculesplugin-autotooltip__plain plugin-autotooltip_bigSolar spicules

"Spicules comprise one of the most fundamental components of the solar chromosphere. They appear to be jets of gas seen at the limb of the Sun in chromospheric spectral lines, and have been observed in Hα and other chromospheric spectral lines for over 100 years. They have an upward mass flux 100 times that of the solar wind, and therefore are an important consideration in the mass balance of the solar atmosphere.; String theoryplugin-autotooltip__plain plugin-autotooltip_bigString theory

unfalsifiable

String Theories are theoretical frameworks which try to describe various observed phenomena in quantum physics and cosmology.

They first originated in the 1960s as an attempt to understand unexplained aspects of the Strong Force which holds atomic nuclei together.; Expansion of the universeplugin-autotooltip__plain plugin-autotooltip_bigExpansion of the universe

unknowable

Current cosmological theory, backed up by many diverse observations, suggests that the universe is not only expanding, but that the speed of expansion is accelerating over time. Thus the limit of the observable universe is not only receding away from us (and from every other location in the universe) but the speed at which it recedes is increasing.; Cosmological wormholesplugin-autotooltip__plain plugin-autotooltip_bigCosmological wormholes

"Wormholes are hypothetical entities that show up in theoretical analyses of Einstein's theory of gravity (general relativity). Nobody has yet seen a wormhole, nor are we certain that they exist, but they seem to show up so easily when we do calculations that many physicists suspect that they might actually be out there in the real universe."; Coherersplugin-autotooltip__plain plugin-autotooltip_bigCoherers

In the 19th century, surprising electrical properties were discovered in imperfect electrical connections between metals. A familiar example to the modern-day engineer is the intermittent faults caused by cold solder joints, other imperfect connections also include copper rods in loose contacts, loose springs, metal screws with a sharp tip, etc,. Initially, because the connection is loose, its electrical resistance is very high. But an one-time application of even a small voltage well …; High Temperature Superconductivityplugin-autotooltip__plain plugin-autotooltip_bigHigh Temperature Superconductivity

functionality_unexplained

The first 'high-temperature' (defined as above --196.2°C) superconductor was discovered in 1986 by IBM researchers Karl Müller and Johannes Bednorz - for which they were awarded the Nobel Prize in Physics in 1987. Since then many other materials with even higher superconducting temperatures have been identified.; Metallic whiskersplugin-autotooltip__plain plugin-autotooltip_bigMetallic whiskers

From the early days of electronics, it was found that some metallic components, especially the lead-based (Pb) and tin-based (Sn) soldered connections, tend to slowly grow conductive 'metal whiskers' (MWs) which can cause short-circuits and severely affect the reliability of systems.; Negative Massplugin-autotooltip__plain plugin-autotooltip_bigNegative Mass

The idea that some exotic forms of matter might have 'negative mass' was first proposed in the 1950's.

In 2017, a team from Washington State University described an set of experiments which claimed observation of negative mass particles.; Snowflake formationplugin-autotooltip__plain plugin-autotooltip_bigSnowflake formation

Snowflakes mostly form in two different types - plate-like and column-like - but there are many others, including needle-like, prism-like and star-like etc.. Although the many types have been extensively documented, and have been found to be temperature dependent (e.g. large stellar types only grow in a narrow temperature range around -15C) the molecular physics driving the different shape formations at different temperatures is poorly understood.; Sonoluminescenceplugin-autotooltip__plain plugin-autotooltip_bigSonoluminescence

Sonoluminescence is the emission of very short (pico-second) pulses of light from imploding bubbles in a liquid when it's subjected to strong sound waves. It was discovered in 1934 during sonar experiments at the University of Cologne.; Wrinkling in surfacesplugin-autotooltip__plain plugin-autotooltip_bigWrinkling in surfaces

"Wrinkles have been in the limelight for their theoretical importance in understanding geometric nonlinearities in elasticity and also for their practical significance in emerging engineering applications such as lithography-free micropatterning; The EMC effectplugin-autotooltip__plain plugin-autotooltip_bigThe EMC effect

"The atomic nucleus is made of protons and neutrons (nucleons), that are themselves composed of quarks and gluons. Understanding how the quark-gluon structure of a nucleon bound in an atomic nucleus is modified by the surrounding nucleons is an outstanding challenge.; Quantum entanglementplugin-autotooltip__plain plugin-autotooltip_bigQuantum entanglement

Quantun Entanglement was first predicted by Albert Einstein, Boris Podolsky, and Nathan Rosen in 1935.

It has now been (unequivocally) experimentally demonstrated with photons, neutrinos, electrons, and even molecules and crystals :

In 2019, it was announced that 'superposition' had been achieved in an organic compound with more than 2,000 atoms. (ref.; Muon magnetic momentplugin-autotooltip__plain plugin-autotooltip_bigMuon magnetic moment

Recent (2021) analysis of experiments carried out at the US Fermilab accelerator have found that the 'magnetic moment' (magnetic field strength) of the Muon is not in exact agreement with calculations derived from the Standard Model

The experiments are a confirmation of previous results from US Brookhaven National Laboratory (BNL) in 2001, which also found anomalies.; Proton Mass Calculationsplugin-autotooltip__plain plugin-autotooltip_bigProton Mass Calculations

The mass of a proton has only been calculated to an accuracy of around 4% - (roughly 938 MeV/c2 or 1.672 × 10-27 kg). The constituent particles - quarks and gluons - which make up the proton, have individual masses that add up to only around 1% or so of its measured mass (which can be determined accurately with specialised devices called; Proton poliarizabilityplugin-autotooltip__plain plugin-autotooltip_bigProton poliarizability

There are still many uncertainties regarding the inner workings of protons (and neutrons) See : Proton structure.

Beginning in year 2000, a series of experiments began to show anomalies in the behaviour of the proton's sub-components (quarks and gluons) when exposed to strong magnetic and electric fields.; Proton structureplugin-autotooltip__plain plugin-autotooltip_bigProton structure

The 'textbook' explanation for the structure of the proton is that it's a 'state' of two up quarks and one down quark bound by gluons, But it has been known for 40 years or so that this is an over-simplification. According to accepted quantum theory, there should also be infinite varying probabilities for the inclusion of quark–antiquark pairs.; Quantum 'Cheshire Cat' phenomenaplugin-autotooltip__plain plugin-autotooltip_bigQuantum 'Cheshire Cat' phenomena

The Quantum Cheshire Cat (QCC) phenomenon was first proposed in a 2013 paper for the New Journal of Physics (ref.) The authors proposed that at quantum level, a particle's properties (e.g. polarization, momentum, spin etc etc ); Alexithymiaplugin-autotooltip__plain plugin-autotooltip_bigAlexithymia

undefined

Alexithymia is a personality trait characterized by the inability to identify and describe emotions experienced by one's self and others.

It was first described, and named, in 1970, but a precise definition of the trait is still lacking :; Borderline Personality Disorder (BPD)plugin-autotooltip__plain plugin-autotooltip_bigBorderline Personality Disorder (BPD)

"Borderline personality disorder is a mental illness that severely impacts a person’s ability to regulate their emotions. This loss of emotional control can increase impulsivity, affect how a person feels about themselves, and negatively impact their relationships with others."; Brief Psychotic Disorder (BPD)plugin-autotooltip__plain plugin-autotooltip_bigBrief Psychotic Disorder (BPD)

"Brief psychotic disorder (BPD) according to DSM-5 is the sudden onset of psychotic behavior that lasts less than 1 month followed by complete remission with possible future relapses.

Source : Stephen A, Lui F. Brief Psychotic Disorder. [Open Access] In: StatPearls."

It presents one or more of the following symptoms :; Functional Neurologic Disorder (FND)plugin-autotooltip__plain plugin-autotooltip_bigFunctional Neurologic Disorder (FND)

Functional Neurologic Disorder - also known as Conversion Disorder, hysteria or psychosomatic illness - is a a common neuro-behavioral / neuro-psychiatric condition where patients experience limb weakness, paralysis, blackouts, movement disorders, vision disorders, speech disorders and other varied symptoms - but without any obvious physical cause.; Stutteringplugin-autotooltip__plain plugin-autotooltip_bigStuttering

Stuttering, estimated to affect 55 million people worldwide, is defined as :

"- a disruption in the fluency of verbal expression characterized by involuntary, audible or silent, repetitions or prolongations of sounds or syllables"

Source :; .99 price discountingplugin-autotooltip__plain plugin-autotooltip_big.99 price discounting

Retailers have known for decades that they can sell more items if they set a price ending in .99. So, for example selling at €3.99 rather than at €4

Anecdotal evidence relates that pricing at n.99 can often sell more goods than pricing even lower - say n.84.; Automaticity a.k.a. 'Autopilot'plugin-autotooltip__plain plugin-autotooltip_bigAutomaticity a.k.a. 'Autopilot'

Most people who routinely drive to and from their workplace will have experienced 'Highway hypnosis' (ref.) at some stage. In other words, arriving at their destination with little or no recollection of the drive.

Leading to the idea that either :; Charpentier illusionplugin-autotooltip__plain plugin-autotooltip_bigCharpentier illusion

The Charpentier Illusion (a.k.a. the Size-Weight Illusion) was first formally demonstrated in 1891 (ref.)

Experimental subjects are shown two objects of differing sizes (but which have been carefully designed to have identical weights). Most people guess that the larger object might be heavier, but, when asked to pick them up; Chewing gum and cognitionplugin-autotooltip__plain plugin-autotooltip_bigChewing gum and cognition

Chewing gum of various kinds has been used for thousands of years.(further historical info,) In the last 100 years or so, various academic research projects have suggested that chewing gum can enhance various aspects of human cognitive behaviour. In particular, increasing attention and concentration.; Childhood amnesiaplugin-autotooltip__plain plugin-autotooltip_bigChildhood amnesia

Childhood Amnesia refers to the inability of adults to remember events from their infancy and early childhood. Typically, most people can't accurately remember anything form their very early life - i.e. before 2yrs, and in some individuals up to 6yrs.; 'Choking' (sports etc)plugin-autotooltip__plain plugin-autotooltip_big'Choking' (sports etc)

The 'Choke' phenomenon is a ubiquitous syndrome which affects sports participants - and is also commonly seen in non-sports scenarios.

In a typical 'choke' scenario, when a player is presented with the opportunity for an exceptionally big 'win', he/she suddenly loses concentration and misses the opportunity at the last moment. It affects professionals and amateurs alike,; Colour perceptionplugin-autotooltip__plain plugin-autotooltip_bigColour perception

Human retinas have four types of light receptor cells. The highly sensitive 'Rod' cells are active in low light conditions, but don't contribute at all to color vision.

There are also three* [see note below] different types of 'Cone' cells which respond differently to coloured light (i.e. different wavelengths).; Déjà vuplugin-autotooltip__plain plugin-autotooltip_bigDéjà vu

Déjà vu - from 'already seen' in French - is the feeling that one has experienced, or even 'lived through' a particular situation before - but accompanied by the belief that, in reality, one hasn't.

"It is an anomaly of memory whereby, despite the strong sense of recollection, the time, place, and practical context of the "previous" experience are uncertain or believed to be impossible.; The 'drunken monkey' hypothesisplugin-autotooltip__plain plugin-autotooltip_bigThe 'drunken monkey' hypothesis

Alcohol Use Disorder (AUD) is one of the most common addictive substance abuses. It's estimated that in the US alone, there more than 3 million early deaths each year as a result.( ref.)

Leading to the question - why do humans have such a preference for alcohol?; Ego Depletionplugin-autotooltip__plain plugin-autotooltip_bigEgo Depletion

Ego depletion refers to the idea that self-control, or 'willpower', is a limited mental resources that can be 'used up' - leaving an individual with limited self-control.

"In a state of ego depletion, an individual's impaired ability to self-regulate can be implicated in a wide range of undesirable and maladaptive behaviors, such as acts of aggression."; Flower Preferenceplugin-autotooltip__plain plugin-autotooltip_bigFlower Preference

"Although the aesthetic appreciation of flowers is a well-known aspect of human behaviour, theories explaining its origin are missing. The only exception is the evolutionary theory of Heerwagen and Orians. Surprisingly, it has not yet been empirically tested."; Forgettingplugin-autotooltip__plain plugin-autotooltip_bigForgetting

"Although it is commonly accepted that learning and memory occur via enduring changes in neuronal properties such as synaptic strength within a network of neurons, many details of these processes remain unknown, including the mechanisms responsible for the persistence and maintenance of memory over long periods of time."; Humour evolutionplugin-autotooltip__plain plugin-autotooltip_bigHumour evolution

"There are several reasons to suppose humor and laughter could be evolutionarily adaptive. [...] the complexity of humor implicates an established genetic substrate that in turn could suggest evolutionary adaptiveness. Given that even a simple joke can utilize language skills, theory-of-mind, symbolism, abstract thinking, and social perception, humor may arguably be humankind's most complex cognitive attribute. Despite its ostensible complexity, humor is also paradoxically ref…; Inner speechplugin-autotooltip__plain plugin-autotooltip_bigInner speech

"When people reflect upon their own inner experience, they often report that it has a verbal quality (Baars, 2003). Also referred to as verbal thinking, inner speaking, covert self-talk, internal monologue, and internal dialogue, inner speech has been proposed to have an important role in the self-regulation of cognition and behavior in both childhood and adulthood,; Kissingplugin-autotooltip__plain plugin-autotooltip_bigKissing

"Kissing between sexual and/or romantic partners occurs in over 90 percent of human cultures (Eibl-Eibesfeldt, 1970; Fisher, 1992). Even in cultures where kissing is nonexistent or condemned, sex partners may blow in each other’s faces, lick, suck, or rub their partner’s face prior to intercourse (Ford and Beach, 1951).; Masochism (physical)plugin-autotooltip__plain plugin-autotooltip_bigMasochism (physical)

There aren't any clear statistics for the number of people who derive pleasure from the physical pain of an activity (irrespective of any other possible benefit). Nevertheless, it's a well-known, widespread and varied phenomenon.; Microsaccadesplugin-autotooltip__plain plugin-autotooltip_bigMicrosaccades

Microsacaddes (lit. trans. 'tiny pulls') are very small involuntary eye movements that are ubiquitous in mammalian vision. They've been known-about and studied since the mid 1880s.

When fixed on any particular scene, the eyes tend to rapidly and repeatedly 'scan' the scene over a tiny range of less than 1 degree of the visual field.; The Moral Superiority Illusionplugin-autotooltip__plain plugin-autotooltip_bigThe Moral Superiority Illusion

"Most people strongly believe they are just, virtuous, and moral; yet regard the average person as distinctly less so."

Source : The Illusion of Moral Superiority [Open Access]Social Psychological and Personality Science, Volume: 8 issue: 6, page(s): 623-631"

The quote above is from a comprehensive study by Royal Holloway, University of London, conducted in 2016, which concluded that :; Musical appreciationplugin-autotooltip__plain plugin-autotooltip_bigMusical appreciation

Music psychologists are trying to understand the processes that support musical behaviours - including perception, comprehension, memory, attention, emotional effects, and performance.

"Music is more mysterious than language because its; Neuronal recycling hypothesisplugin-autotooltip__plain plugin-autotooltip_bigNeuronal recycling hypothesis

Why do modern-day humans have a seemingly in-built ability to learn highly complex procedures, which our ancestors, just a few hundred generations ago, would have never needed?

The neuronal recycling hypothesis was developed in the early 2000s as an attempt to explain the so-called; Numerical cognitionplugin-autotooltip__plain plugin-autotooltip_bigNumerical cognition

Many animals have demonstrated abilities to count numbers - a.k.a Numerical Cognition. This fits in with evolutionary theory in the sense that it could be advantageous for an animal to understand (small) numbers when involved in feeding, threat situations etc.; Psychobioticsplugin-autotooltip__plain plugin-autotooltip_bigPsychobiotics

It's been known for many years that the microbiome (the bacterial and viral components of gut contents) can affect the physical wellbeing of mammals, including humans.

It's recently been suggested that the micro-organisms might also be able to affect humans'; The Return Trip Effect (RTE)plugin-autotooltip__plain plugin-autotooltip_bigThe Return Trip Effect (RTE)

Many will have experienced the Return Trip Effect (RTE), whereby the outgoing journey to a destination (any mode of transport) very often 'seems' considerably longer than the return over exactly the same route.

As well as being widely-experienced, the effect is readily reproduced in lab-based experiments - and has been quite extensively investigated.; Rhythm perceptionplugin-autotooltip__plain plugin-autotooltip_bigRhythm perception

Humans (and some other animals*) have an innate sense of 'rhythm', i.e. the ability to detect and react with 'beats' in musical compositions. Professional drummers and percussionists can 'beat time' with accuracies of just a few milliseconds per beat (ref.; The 'stopped clock illusion'plugin-autotooltip__plain plugin-autotooltip_bigThe 'stopped clock illusion'

When quickly glancing at an analogue clock with a second-hand, it often seems that the second-hand is 'stuck' for the first second - in other words the first tick of the hand appears to take longer than it should. In many cases the hand can even seem to step; Telescoping effectplugin-autotooltip__plain plugin-autotooltip_bigTelescoping effect

The Telescoping Effect, first named in 1964, refers to the tendency that many people have for mis-judging the time at which events have happened. In general, recent events are judged as being more remote than they were, and distant events as being more recent than they were.; Time Awarenessplugin-autotooltip__plain plugin-autotooltip_bigTime Awareness

"Anticipating events that will happen in the future is among the most important functions the brain performs. Indeed, it has been increasingly stressed that learning and memory are prospective brain functions; that is, they are only adaptive to the extent that they help animals anticipate and prepare for the future (Dudai and Carruthers, 2005; Schacter and Addis, 2007). To anticipate when events will happen, the brain has evolved mechanisms to tell time across a wide range of te…; Tip of the tongueplugin-autotooltip__plain plugin-autotooltip_bigTip of the tongue

"Tip of the tongue (or TOT) is the phenomenon of failing to retrieve a word from memory, combined with partial recall and the feeling that retrieval is imminent. The phenomenon's name comes from the saying, "It's on the tip of my tongue." The tip of the tongue phenomenon reveals that lexical access occurs in stages.; The 'Uncanny Valley' hypothesisplugin-autotooltip__plain plugin-autotooltip_bigThe 'Uncanny Valley' hypothesis

The Uncanny Valley hypothesis was first noted in 1970 by Masahiro Mori, professor of engineering at the Tokyo Institute of Technology, in his book entitled Bukimi No Tani (translation).

It refers to the idea that when people view human-like artificial characters which are not; Unconscious thought theoryplugin-autotooltip__plain plugin-autotooltip_bigUnconscious thought theory

Unconscious Thought Theory (UTT) refers to the idea that that people may be able to 'work through' complex problems without necessarily paying conscious attention.

Many will have had the experience of waking in the morning with a solution to a problem that had previously proved difficult or impossible to resolve using conscious thought. A similar phenomenon is when someone has a 'Eureka' moment when; Newsplugin-autotooltip__plain plugin-autotooltip_bigNews

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• Oct 2024 : In keeping with many other sites, Wikenigma has now cancelled and deleted its Twitter/X account.

• July 2024 : Wikenigma clarifies that the site's CC licence - which is used for all orignal content - expressly disallows any 'scraping' and re-use by AI systems. See :; Editing articlesplugin-autotooltip__plain plugin-autotooltip_bigEditing articles

Note: Editing and creation of articles is currently restricted to registered users. See 'Notes for Contributors' in the 'Utilities' section of the main menu.

Once you're logged in, a grey floating 'Tool' menu at the right hand side of the screen enables access to all the main 'Content' articles for editing.

This list might not be complete due to ACL restrictions and hidden pages.

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