Le site de vulgarisation scientifique de l’Université de Liège. ULg, Université de Liège

Glossary

Vous trouverez dans ce glossaire les définitions de termes présents dans les différents articles, classés de manière alphabétique.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
S
Saccharide

Glucides are a group of broadly defined molecules: they are made up of carbon, hydrogen and oxygen; the simplest of them are simple sugars, called monosaccharides. Disaccharides are made up of two agglomerated monosaccharides (the most well-known example is saccharose); they often serve to transport sugar in the body. Polysaccharides are created through the agglomeration of several saccharides. This is the case for starch or cellulose.

Saint Jerome (circa 347-420)

A Father of the Church, who was born in Dalmatia and died in Bethlehem. After his classical studies and his travels to Gaul, this erudite polyglot retired to the East. He has above all remained famous for his translation of the Bible into Latin (390-405), commonly known as the Vulgate, and which subsequently became the official version of the Catholic Bible. He is also well known through the numerous representations he has been the subject of in Western art; in them we see him, as a reclusive hermit or as a learned man, studying in his cell, often accompanied by a lion which he had cared for in his Bethlehem monastery by removing a thorn from its paw and whose friendship he had thus gained.

Salmon, André (1881-1969)

French writer born in Paris and who died in Sanary-sur-Mer (department of Var). After spending part of his childhood in Saint Petersburg, he came into contact pretty early in his youth with Max Jacob, Guillaume Apollinaire and Pablo Picasso. For the latter, who exerted great influence over him, he contributed to making known his painting, Les Demoiselles d'Avignon, seeing in it ‘a still glowing crater from which emerged the fire of contemporary art.’ He participated in the revolution of modern art as a critic. But he also shone in other domains; as a poet, he published several collections and became the secretary of the Paul Fort’s journal, Vers et Prose; as a novelist he in particular gave an account of life in Montmarte in La Négresse du Sacré-Cœur; as a journalist he was intensively active. But his reporting of the Spanish Civil War, quite favourable to the nationalists, as well as his contributions to the Petit Parisien during the Occupation, caused him problems on the Liberation.

Sam Taylor-Wood

photographer and video-maker born in 1967 in England, graduated from Goldsmiths College. His best known work, testifying to the vitality of contemporary plastic photography, includes Soliloquy (1998-2000), Self portrait suspended (2004) and Crying men (2002-2004). He uses colour and black and white, and his photos show familiar masculine faces, often in tears.

saprophyte

An organism that feeds off decaying organic matter through a membrane.

Sartre, Jean-Paul (1905-1980)

A French writer and philosopher, Sartre was a symbol of the "engaged" intellectual and developed the concepts of existentialism and phenomenology: human beings cannot deny their freedom and bear entire responsibility for their actions towards others and themselves.

At the political level, he supported Algerian independence and the Cuban revolution, as well the May 1968 revolutionary movement in France.

Satellite account

This is a group of statistical tables that can be linked to the national accounts but in which a specific approach can be adopted for the field being examined and elements added that do not feature in the national accounts, in order to more faithfully describe the economic reality in this field.

Satrapi, Marjane

A French comic script author of Iranian origin. She was born in Rasht in Iran in 1969. She became famous for her series of four comic strips called Persepolis (published in L'Association) and by her cinema adaptation of the same name.

Saturated and unsaturated fats

Fat or fatty acids are the organic molecules which make up a carbon chain supporting a carboxylic group (R-COOH: the carbon atom linked by a double bond to an oxygen atom and by a single bond to an OH hydroxyl group), at one of its ends and which can consist of one or several double carbon-carbon bonds. If there is no double bond, these acids are called ‘saturated’. If there is a single double bond, they are mono-unsaturated and if there are several double bonds they are poly-unsaturated.

Saxons

A Germanic people established on the shores of the North Sea and in North West Germany. In the 3rd and 4th centuries they ravaged the coasts of Gaul and Great Britain; in the middle of the following century, certain of them conquered, along with the Angles, the eastern part of the British isle today called ‘England.’ Charlemagne set out to bring to heel the Saxons who remained in Germania: from 772 until 804 he carried out hand in hand military expeditions and forced Christianisation.

Saxony, Maurice of

Maurice, Count of Saxony, known as the Marshal of Saxony (1696-1750). He was a military leader and warrior from his youth and a gifted strategist. He distinguished himself in campaigns that were part of the War of Austrian Succession. He died at the chateau of Chambord after a turbulent private life.

Scanning electron microscope

Microscope which provides images using the interaction between an electron beam and the matter of the sample to be studied. More specifically it consists of an electron beam which sweeps the surface of the sample to be analysed. In response to this scanning, the sample emits certain particles which, once analysed by various detectors, allow a three-dimensional image to be reconstructed.

Schizophrenia

A set of psychiatric pathologies which usually begins in adolescence or early adulhood and causes an altered perception of reality, cognitive disorders and social and behavioral dysfunction.

Schrauwen, Olivier

A Belgian comic strip writer and illustrator born in 1977.

Schuiten, François (1956 - )

François Schuiten, born April 26, 1956 in Brussels, is a Belgian comic artist and scene painter. He became famous through his work on Cités obscures, with the scenario writer Benoît Peeters, and received the Grand Prix of the City of Angoulême in 2002.

Schuman, Robert (1886-1963)

A male French politician, considered as one of the founding fathers of European construction. Born a German in Luxemburg through a conjunction of family and historical happenstance, this Lorraine lawyer, educated across the Rhine at Strasburg, became French in 1918. Which is to say that he seemed predestined to consider borders as totally relative and surmountable boundaries. A member of parliament for Mosel from 1919 to 1940 he subsequently became a state undersecretary for refugees, and was then deported to Germany, from where he escaped. Several times a minister (MRP : Mouvement républicain populaire, Christian Democrat), notably Foreign Minister and President of the Council (Prime Minister) under the fourth French Republic, he became, along with Jean Monnet, an important promoter of European construction. He laid the foundations of the European Coal and Steel Community (ECSC) and the European Defence Community (EDC), but the latter project was abandoned in the face of opposition from communists and Gaullists. Robert Schuman devoted the end of his life to the development of European institutions as President of the European Movement, and then the Parliamentary Assembly of Europe at Strasburg, from 1958-1960.

Schwartz, Olivier

A French comic trip cartoonist born in 1963. He created the series Les enquêtes de l'Inspecteur Bayard and also takes part in other projects, such as Le Groom vert-de-gris, a Spirou and Fantasio adventure, for Dupuis publishers.

sciatica

Sciatica is a tracer pain starting from the lumbar region (back), reaching the buttocks and posterior section of the thigh and the knee, and extending down the legs; it is caused by an irritation of the sciatic nerve.

Scoriae

Scoria (or ‘slag’) is a soily or rocky vitreous substance produced residually by the fusion of metals. In the case of iron ore, it is the result of the partial melting down of the ore. By analogy, the term also designates the produce of volcanic eruptions.

Second Empire

A constitutional and political system instituted in France on December 2, 1852, when the President of the Republic, Louis-Napoléon Bonaparte, became Empereur of the French, taking the name of Napoléon III. This system ceased to exist on September 4, 1870 following the French defeat at Sedan, during the war against Prussia.

secondary atmosphere

This is an atmosphere surrounding the planet after its eventual loss of its primary atmosphere, and whose origin is the degassing of the surface of the planet and the impact of comets and asteroids containing volatile gases. As an example, the atmosphere of the Earth is secondary and results from volcanic activity. The supposed atmosphere of 55 Cancri e is also secondary and consists mainly of water vapor according to some models.

Sediment

A deposit formed by the precipitation of substances suspended in a liquid. In geology, it concerns deposits abandoned by water sources, wind and ice.

Self-defining memories

Very vivid memories, often recapitulated and emotionally charged, which play an important role in the construction of the self-image.

Semiconductor

A semiconductor is a non-metallic material that imperfectly conducts electricity. It is an intermediary between a metal that perfectly conducts electricity and an isolator that does not conduct electricity.

Semiochemical

A substance emitted by an animal or plant and which serves as a signal between living beings.

Semiotics

the science or discipline of meaning, which attempts to describe how meaning is produced or articulated, and also the means of approach to this meaning. In consequence it is a reflection on the instruments that are intended to grasp and describe this meaning, since it is understood that the word ”meaning” must be taken in the sense of “deployment” or “orientation”. While this discipline pushes as far as possible with its questioning about meaning, semiotics is thus called to approach the sacred, to the extent that the sacred is a phenomenon that constantly interrogates the meaning of meaning or the value of value.

septentrional

Adjective describing what is from the north, situated in the north (the opposite to meridional, which describes what is situated in the south).

Septorhinoplasty

Surgery consisting of an intervention aimed at straightening the septum inside the nose.

Serotonin

Neurotransmitter produced by certain neurons in the brain. This substance plays an important role in the functioning of the brain, notably concerning mood, emotivity and sleep. A dysfunction in its production could intervene in the onset of depression.

Serotype

This comprises all the antigenic characteristics (the body’s defence mechanism against a foreign body) of certain microbes such as viruses, bacteria, fungus, algae, etc., which allow us to differentiate between the strains that belong to the same species.

Serum

a liquid component of blood, of a yellowish colour (around 80% water), containing erythrocytes (red globules), leukocytes (white globules) and thrombocytes (platelets), but no fibrins or other agents responsible for coagulation.

Seventh continent

This is the name given to a gyre of marine waste particles in the North Pacific, discovered in 1997 by the oceanographer Charles Moore. This “continent” is translucent and is situated under the water’s surface. It is therefore not detectable by satellite images. An international study published in the journal PLOS ONE estimates that, in total, there are around 269,000 tonnes of floating plastic. This enormous garbage patch, (the size of Texas) rotates and is constantly fed by new waste particles.

Seveso

On July 10, 1976, toxic vapours of dioxin escaped from the Icmesa factory in the north of Italy. The incident only led to twenty slight injuries but, a toxic polychlorinated compound, the dioxin set in throughout the whole food chain. The contamination of the soil explains the restrictions imposed over 1,800 hectares of the surrounding area (of which a large part of the commune of Seveso), whilst the buildings occupying the 110 hectares closest to the leak were razed to the ground. The contamination will only completely disappear in 2040. Following on from this, in 1982 the European Community adopted a directive which aims at preventing such industrial disasters. It bore the name of Seveso.

Sex Pistols

A punk group active at the end of the 1970s. For the group, musical mediocrity and a ‘don’t care’ attitude were the guarantors of a spontaneity and an authenticity which were initially specific to rock but had been lost through the excess of virtuosity of the groups making music at the beginning of the decade. They decided, in their music, to wipe the slate clean of all the music of the past. If the group today has a legendary aura, at the time it was only number one in the English hit-parade for a single week.

shale gas

Shale gas is a natural gas that has been exploited on a grand scale since the beginning of the noughties.This gas, which is considered to be an alternative to hydrocarbons, is captured in rock reservoirs at great depths (1500 to 3000 meters). The extraction of shale gas is costly and particularly delicate because it combines two techniques: drilling and fracking. The United States - which has played a pioneering role in the exploitation of this natural resource - and South America possess many mining facilities for shale gas. Some countries are very cautious about allowing the extraction of this gas within their territories because even though this gas is an alternative to hydrocarbons, the technique involved in its extraction pollutes water reserves and increases greenhouse gas emissions.

Shannon, Claude (1916-2001)

An American engineer and mathematician, the father of the information theory, initiated during the Second World War. Information theory deals the communication between machines (source-encoder-signal-decoder-recipient). Shannon also carried out work on the theoretical limit of the compression of a message or the capacity of a transmission channel.

Shining Path

Its real name being Partido Comunista del Peru Sendero Luminoso, the Shining Path is a terrorist movement inspired by Maoism born in Peru in the 1970s through the drive of a philosophy professor, Abimaël Guzman. Calling for a popular war, it has been responsible for the deaths of several thousand people. Guzman was arrested in 1992. Since then the movement has lost momentum.

Shoah

From the Hebrew word meaning ‘catastrophe.’ Designates the genocide of the Jews by Nazi Germany, between 1933 and 1945.

short term memory

According to Alan Baddeley, of the University of Bristol’s psychology department, short term memory, in the same way as long term memory, submits to the game of subdivisions. At the top of the pyramid, a central administrator, also called an attentional manager, fulfils the functions of an orchestra conductor. In the hypothesis of a mental calculation, for example, it would manage how operations unfold. Nonetheless, because of limited resources, it cannot manage and store at the same time; consequently it would leave it up to slave systems to carry out the task of temporarily storing information.

At this point in time, Baddeley’s model only contains two systems of this type: the visio-spatial register, for mental images, or the phonological loop, for verbal elements. But it is conceivable that other entities of the same nature exist, related for example to motor information. In Baddeley’s approach the phonological loop contains two components: the phonological store, which retains sounds – words – for a few seconds in the memory, and the mechanism of articulatory recapitulation, which reintroduces these elements continually in order that they remain available for the necessary time.

Short-term phonological memory

System responsible for temporarily storing verbal information. Short-term phonological memory essentially fulfils two functions relating to the process of acquiring reading skills. On the one hand, it promotes long-term learning of grapheme-phoneme correspondence. On the other, it retains phonological information for the time required to convert it when needed for phonological recoding - moving from the orthographic form to the phonological form.

shot

A narrative unit within cinema. A shot is a series of frames recorded by the camera in an uninterrupted way.

si-RNA

Small interfering RNAs which link specifically to an RNA messenger sequence prevent the expression of genes.

SIEFED (method)

A patented technique designed by CORD, the SIEFED method for “Specific Immuno Extraction Followed by Enzymatic Detection” is an original measuring technique for the activity of an enzyme in a complex biological milieu without interference from the components of this milieu on the measurement of enzyme activity. It is thanks to this technique that the modulation effect of vegetable extracts or molecules is directly demonstrated on the enzyme.

Siegfried Bing (1838-1905)

Originally from Hamburg, Siegfried Bing joined his family in Paris in 1854, where he worked for a company that specialised in the sale of china and ceramics. Forced to leave France in 1870 because of the Franco-Prussian war, he came to live in Brussels. Nevertheless, he returned to Paris in 1871, and began his collection of Japanese objets d’art, earning himself a solid reputation. After a trip to Tokyo, he opened a shop dedicated to Japanese art in 1878 – the date of the Universal Exhibition in Paris. Bing acquired his goods directly from Japan, increased the number of shops, organised exhibitions. Conscious of the reputation of his business, he even exhibited his works outside of France, in Copenhagen and Brussels.

signalling pathway

A cascade of molecular reactions occurring during a cellular process

silica

A natural form of silicium dioxide (SiO₂) which is involved in the composition of many minerals. It can be reduced by carbonreduction (en un mot : carboreduction) in ovens at temperatures in excess of 2000°C.

silicates

Minerals formed from SiO4. They constitute the main family of minerals (olivine, quartz, pyroxene, etc.) and form part of the composition of magmatic rocks.

Single European Act

This treaty, which came into force on July 1, 1987, implemented the adaptations necessary to complete the vast European internal market.

singlet oxygen

A diamagnetic form of the molecule of dioxygen. It is an excited singlet state.

Sinn Fein

An Irish nationalist, Catholic and Republican movement founded in 1905, whose name means ‘Ourselves Alone’ in Gaelic. Following the Second World War, it became the political wing of the IRA, and demanded that Ulster (Northern Ireland) be re-integrated into the Irish Republic. A legally recognised party, presenting candidates for elections, Sinn Féin was little by little incorporated into the negotiations which led to the peace agreement of 10th April, 1998. On 28th January 2007, Sinn Féin acknowledged the powers of Northern Ireland’s police force, until then seen as a ‘legitimate target’, which opened the way to its participation in Northern Ireland’s government. The party today has 5 elected members in London’s parliament and two elected members in the European parliament.

skeletal muscle mass index

This is obtained by dividing the Appendicular muscle mass by the waist squared. The suggested standard is 7.26 kg/m² for men and 5.5 kg/m² for women.

skeletal muscles

Muscle made up of a set of fasciculi of muscle fibers most of which are fast. Muscles under voluntary control of the central nervous system. It is thanks to the skeletal muscles that the body is maintained, that the joints are stable, that movement is possible and that energy is produced by means of contractions of variable intensity. 

Skyline

A term meaning the horizon line. It is interesting to analyse it to define the average height of buildings and their horizontal organisation.

slow twitch muscle fibers

Muscle fibers that contract slowly and weakly but which have a greater resistance to fatigue.

Social burden

Ratio of all the “dependants” against the working population alone.

Social dialogue

According to Lentic, the Laboratory for the Study of New Technologies for Information, Innovation and Change, the term social dialogue refers to procedures of cooperative discussion followed by social partners or their representatives at any level (business, region, nation, Europe). Social dialogue includes discussions between partners, their negotiations, their joint actions and their relations with public authorities. In most European States, apart from those who have only recently become member states, dialogue between social partners is an integral part of the processes of social concertation practiced at the national or sectorial level or within businesses, whose existing structures constitute the backbone of their social model.

Social economy

Collection of economic activities exercised by associations, foundations, mutual benefit societies, companies with a social purpose and co-operations (that pursue a co-operative ideal). These activities are exercised while pursuing a common ethical code which is translated into the respect of four criteria: confirmation of a purpose to provide a service, independent management, a democratic decision-making process, primacy of people and work over capital in the distribution of income.

Sociolinguistics

A part of linguistics which deals with the relationships between language, culture and society. It shows in particular that language is not only a system serving communication, but also a way for us to situate ourselves in the social fabric.

Socrates (470-399)

A Greek philosopher considered as the founder of Western philosophy, even though he left behind no written work. We know him above all through Plato. The son of a midwife, he said he had inherited from her the art of giving birth not to bodies but to sprits. His method, known as maieutics, consisted of dialoguing as much as possible with the people he met at Athens, making them first of all aware of their ignorance; making use of irony he would ask them questions, drawing responses and, after having thus provoked confusion in their consciousnesses, he would step by step lead them to the discovery of knowledge. His preoccupations were essentially moral: he taught his fellow citizens to think by and about themselves, in short to know themselves better. He was persuaded that the men who had rid himself of prejudices could not but live in goodness and truth. His independence of spirit earned him condemnation to death by the popular tribune of the Athenian city.

Sol/gel (process)

The sol-gel process makes possible the fabrication of non-fusion vitreous materials by simple polymerisation of molecular precursors in solution. The great advantage of this procedure is that it is carried out at low temperature (from 20 to 150°C) and allows for use of porous materials. The best-known of these is undoubtedly silica gel, formed from silicon which appears as a set, rigid and transparent liquid made up of a network of polymeric silicon housing the solvent in its pores. It is at this moment that an essential stage of the fabrication of these materials comes into play- the drying. This operation consists in draining off the solvent from the polymeric network.

Solar mass

In astrophysics the Sun’s mass serves as a unit of mass for stars and other bodies. It is the equivalent of close to 2x1030 kg.

Solar wind

Solar ‘wind’ is evidently not a current of air as we normally understand it but is made up of a flow of particles originating from the Sun which constantly sweep the interplanetary environment. The particles are electrically charged. This wind is not particularly dense (10 particles per cubed centimetre) but is very fast (400 to 800 kilometres per second). It is principally made up of electrons, protons and helium nuclei. The solar wind fluctuates wildly.

Somatotopic representation

Location in the brain of areas which intervene in deliberate motricity and sensitivity.

Somesthesic stimulations

Somesthesic stimulations relate to the mechanical forces exerted on the surface of the body and on deep structures such as muscles and joints.

Somesthetic

Relative to a set of perceptions integrating different types of sensations: touch, temperature, kinesthesics (sense of movement), pallesthesia (sense of vibration), deep pressure, statesthesia (sense of position), dynamesthesia (sense of muscular strength), topesthesia (localisation of a sensation), baresthesia (sensitivity to weight).

Sonar

Sonar (the English acronym of SOund Navigation And Ranging) is a detection device based on the reflection of sound waves in marine environments. This system is analogous to Radar, which for its part is based on the reflection of radio waves in the air. The sonar emits ultrasound pulses and receives the waves reflected back with the help of a sensitive detector. It thus enables the 'drawing' of a map of the sea's depths or the detection of the presence of an object in the water, a submarine for example.

Sound spectrum

Music is a sound. And sound is a sine wave. The frequency of this wave determines whether it is perceived as low or high pitched. The higher the frequency the more high pitched is the heard sound. Alternatively, the lower this frequency is the lower the sound is. The sound spectrum which is perceptible by the human ear ranges from the limits of infrasound (2O Hertz) to ultrasound (20,000 Hertz).

Souris, André (1899-1970)

A Belgian composer. He studied at the Brussels Royal Conservatory. In 1925 he met the poet Paul Nougé and joined the Belgian Surrealist movement. Besides his musical work he worked on numerous Surrealist reviews and pamphlets. He was nonetheless expelled from the movement in 1936. He also taught harmony for a number of years at the Brussels Conservatory and played an essential role in introducing serial music into Belgium and France.

South Ossetia

The second South Ossetia war saw Georgia clash with its separatist province of South Ossetia and Russia in August 2008. The Georgian attempt to grab control of its separatist region by force led to an immediate riposte by the Russian army. On the basis that a great majority of South Ossetians have a Russian Federation passport, the Russian President, Dmitri Medvedev, ordered his troops to intervene in order to protect the population of South Ossetia and force Georgian into accepting peace. A cease fire was signed on August 16. On August 26, the Russian Federation officially recognised the independence of Ossetia and Abkhazia and proclaimed itself ready to ‘ensure the security of these two States.’

Souverainism

A political doctrine supporting the political autonomy of a country in the exercise of its sovereignty. In France, this diffuse political current, represented as much on the left as on the right of the political chessboard, militates for a ‘Europe of the Nations’ so that each country sees its particularities and autonomy respected. Its defenders oppose European federalists, who advocate a federal Europe and aspire for a United States of Europe.

Spanish flu

Name given to a flu pandemic caused by a highly virulent viral strain of H1N1. The pandemic appears to have broken out in the USA at the beginning of 1918. The virus progressed at lightning speed: in barely seven days, different sources of infection were found throughout America; in three months, all the continents were affected. It is estimated that a billion people contracted the disease (i.e. almost half the world’s population at the time) and approximately 60 million died. This pandemic, which caused more deaths in several months than the First World War in four years, is undoubtedly the most virulent humanity has ever known in such a short space of time. The nickname “Spanish flu” was given to this disease because the King of Spain, Alfonso XIII, contracted the disease very early on in Europe, not to mention 70% of the population of Madrid in just three days!

speciation

An evolutionary process through which new species appear. Speciation results from natural selection and/or genetic drift, in other words the two motors of evolution.

Species

Species are “groups of natural populations that are actually or potentially capable of interbreeding, and which are genetically isolated from other similar groups,” according to a definition by Ernst Mayr. But since asexual reproduction can occur in animals as in plants, the concept of species cannot be associated only with inter-fertility. In simple terms we can say that a species can be defined as a population whose members can interbreed without difficulty under normal conditions.

In scientific classifications, a species is given a two-part Latin name, including a generic name (which begins with a capital letter), followed by one or two specifying names. For example, human beings belong to the genus Homo, and also to the species Homo sapiens (the system of nomenclature was begun by Linnaeus).

Specific richness

Measure of the biodiversity of an ecosystem. It designates the number of species (animal or plant) present in a given region.

Specific species

In contrast to a ubiquitous species. A species which is specific to an environment is a species whose survival depends on the survival of its environment. It cannot evolve anywhere other than the environment in which it lives, and is dependent on the conditions which it provides.

Spector, Phil (1939 - )

An American producer active during the 1960s. He is famous for having been the origin of what is called in the studio a wall of sound, in other words a technique of increasing the number of instruments, microphones, speakers, etc. with the sole aim of generating a strong and powerful sound.

spectral entropy

Spectral entropy characterises the disturbance present in a signal’s frequency spectrum: in general, a high value corresponds to an increase in irregularity or unpredictability (for instance, a uniform distribution of the power spectrum during awakening) while a low value corresponds to a high level of regularity (for instance, the concentration of the activity in the delta band during deep sleep).

Spectral type O star

Stars are divided into different types, following their spectral characteristics. Those of type O are blue and extremely hot because at their surfaces there reins a temperature of 30,000K and 45,000K, against our Sun’s 6000K. They are also very massive. Their spectrums are characterised by intense lines of helium.

Spectroscopy

This is a technique of analysis that uses optical equipment that allows light to be dispersed as a function of its wavelength. The result is called a spectrum of emission or absorption, according to whether one is analyzing light that has passed through a body, or light that has been reflected by one. These spectra provide important information, since atoms or molecules emit spectra made up of “furrows” that have characteristic wavelengths. Spectrometric analysis thus allows one to detect and measure substances. The dispersing element, which allows the light rays to deviate, is obviously chosen according to the wavelength, and the level of precision required. The oldest and best known of such elements is the prism, already used by Newton in the17th century.

sperm whale (Physeter Macrocephalus)

The biggest carnivore in the world because the male can reach up to 20 metres in length, this cetacean is the last representative of his family, Physeteroidea, with the pygmy and dwarf sperm whales. It is known for its apnoea diving records, reaching depths of three thousand metres, a record unequalled among mammals. The males are the only ones to risk entering the icy waters of the Arctic and Antarctic. Little is still known about the sperm whale.

spermatophore

This is a sperm capsule produced by the male in many invertebrate animals (spiders, insects…). During mating, the spermatophore is transferred to the cloaca of the female (or genital opening).

Sphenopalatine ganglion

The sphenopalatine ganglion is a ganglion belonging to the autonomic nervous system. It receives fibres which come from the brain stem via certain cranial nerves and sends itself fibres to the glands and tissues of the face, like the lachrymal gland, the glands of the nasal and palatine mucosae and eye vessels. It is located just behind the upper jaw, lateral to the upper nasal cavity, in the pterygoplatine fossa. It is involved in the autonomic symptoms of cluster headache attacks and, via its connections with the trigeminal system, in the pain.

sphincter

A circular muscle situated around a duct; by contracting, it makes it possible to close the duct. This contraction can be automatic (reflex) or voluntary. The human body contains several kinds of sphincters: around the anus, the urethra, but also the pylorus, for example, which at the base of the stomach interrupts the passage of food to the bowel.

Spiegelman, Art

An American comic strip writer, born in Sweden in 1948. He is one of the pillars of underground American comic strips of the 1970s-1980s, and who became famous at the end of the 1980s for Maus, a work which won him the Pulitzer Prize in 1992.

Spin

In quantum physics, the "spin" of a particle measures what in classical physics would be the equivalent of the speed of rotation of the particle on itself. But while in classical physics, this speed can be arbitrary, spin can only have precise values, for example +1/2 or -1/2 in the case of the electron.

Spinoza, Baruch (1632-1677)

A Dutch philosopher of Portuguese Jewish origins. He received a Hebraic education. But he also discovered the philosophy of Descartes, the science of Galileo, frequented liberal Christian circles and let himself be won over by the spirit of doubt and the spirit of rationalism. Anxious to call into question political and religious values, and every dogma, Jewish or Christian, he was expelled from the Jewish community and survived as an artisan, as a lens grinder. The majority of his life was nevertheless devoted to philosophy, but the hostility which his Tractatus theologico-politicus (1670) was met with, a work of ‘liberal’ inspiration, convinced him to publish nothing further during his lifetime. Spinoza’s thought presents itself as a liberating message as regards all the constraints and the joys procured by knowledge, this ‘beatitude’ which offers the wise the power to master their passions. Spinoza conceived of life in society as the meeting of beings who have accepted each other. But a right to insurrection exists when public liberty is menaced.

Spiral ganglion

A group of neurones which constitute the first nerve relay of the transmission of sound from the cochlea to the brain.

spore

A reproductive (germ) cell which results from meiosis, capable of developing into adult form without uniting with another cell, ensuring the dispersion of certain plants such as algae, fungi and bryophytes.

Spores

In biology a spore is a reproductive structure which is adapted in order to be dispersed and survive over prolonged periods of time in unfavourable conditions. Spores are a part of the life cycles of many plants, algae, fungi, bacteria and certain protozoa.

spot blotch disease

This is a disease Common in wheat and other cereals which inhibits the growth of plants and can cause losses in crop yields of up to 40%.

Springtime of the Peoples

In 1848, a revolutionary fever progressively took hold in several European countries. A movement called the Springtime of the Peoples or the Revolutions of 1848. This fever was first of all due to the economic crisis of 1847-1848, which led to unemployment and poverty. The movement started from Paris – where the revolution brought down King Louis-Philippe and the monarchy – and then gained ground in the Austro-Hungarian Empire, where it ignited nationalist demands on the part of minorities such as the Czechs, Romanians, etc. Germany was also contaminated. Following these movements and demands several European sovereigns were forced to adopt reforms and a constitutional system…before picking up the reins of power when the revolutionary movement lost momentum.

Sputnik

The first artificial satellite, launched on 4th October from the Baikonur base in the ex Soviet Union. Its name means ‘travelling companion’. The satellite consisted of a small sphere measuring 58cm, weighing 83kg and equipped with a light transmitter.

stable isotope

An isotope that is non-radioactive or sufficiently stable so that its radioactivity is not detectable.  

standard cosmological model

This is the most precise and widespread theoretical model for explaining the history of the Universe and its behaviour. It is based on the premise that the Universe, ever since the big bang 15 billion years ago, is in isotropic expansion, and therefore it has invariable physical properties according to direction, being homogeneous on a very large scale.  Certain anomalies, revealed at the edge of the Universe, in particular by the satellite Planck, but also by the study of bigger quasar structures than the model allows for, tend to demonstrate some of the limitations of this model. More and more theories cast doubt on the fact that the Universe is in isotropic expansion, and suggest that it presents different characteristics in some directions. It could be the case, for example, that it is not expanding at the same speed in all directions.

stasis

State of immobility. In evolutionary studies, morphological stasis characterizes lineages that underwent very few morphological modifications throughout a long time interval.

Stassen, Jean-Philippe

A comic strip illustrator from Liège, born in 1966. In 2000 he won the René Goscinny Prize for the best script and the France Info Prize for his work Deogratias, a comic strip which has as its background the Rwandan genocide. He has developed a very personal style, spanning the large publishing houses and the alternative world.

Statism

A doctrine advocating the extension of the state's role and responsibilities to the entirety of economic and social life.

Stavelot

This town is located in eastern Liège province, in the center of the Haute Ardenne. Stavelot is one of the oldest towns in Belgium. Its Benedictine abbey is ancient. Along with the abbey of the neighbouring town of Malmédy, it was the seat of a bishopric until the time of the French Revolution. Today there are ~7000 inhabitants.

Stax

An American independent record production and distribution company created in Memphis in 1958. Stax was one of the pillars of Soul.

Stem cell

A cell at the origin of every cell. Different types exist, depending on the lines of tissues they will engender. But we call normal stem cells or totipotent stem cells those at the first embryonic stage, in other words those capable of giving birth to all the cells possible.

Stendhal (1783-1842)

Stendhal, a penname, his real name being Henri Beye, is a French writer, reputed for the subtlety of the analysis his characters’ feelings. His work in the novel form consists of only five books, which nevertheless are considered amongst the most beautiful in French literature, in particular The Scarlet and the Black (1830) and The Charterhouse of Parma (1839).

stenosis

Shrinking of a tract or vessel.

stereology

Stereo from ancient Greek meaning “solid”). This is the study of solids in three dimensions from measurements in lower spatial dimensions (eg. 2D sections).

Steroid

A natural organic compound produced from lipids, specifically cholesterol. Sex-related steroids are produced mainly by the testicles and ovaries, which control the physiology of reproduction and secondary sexual characteristics. In women, these hormones are called estrogens and progesterone; in the end they are called testosterone and androsterone. Research into these compounds has allowed them to be synthesized, as with the artificial hormones used in contraceptives.

Stock Market Index

A statistical tool for measuring the performance of a stock exchange or market, the stock market index is calculated based on the averaging of the values of securities of several companies. The index can be general (representing all sectors of an economy) or sector-specific (based on the figures for a particular sector of the economy). For example, the CAC 40 - the French stock market index - is based on the 40 biggest capitalisations of the Paris Stock Exchange. The BEL20 – the Belgian stock market index – regroups the 20 biggest companies trading at the Brussels Stock Exchange.

Stoicism

A philosophical doctrine born in Greece with Zenon of Citium (334-262), which spread throughout Ancient Rome from the 1st century B.C. It recommended the suppression of vain desires in order to escape unfortunate strokes of fate and thus achieve individual happiness. Such behaviour demands of its disciples mastery of the self and a constant will to trace their conduct on reason. Seneca (4 BC – 65 AD), Epictetus (50-130 AD° and Marcus Aurelius (121-180 AD° where, in the first two centuries of the Roman Empire, the best known representatives of this demanding morality. 

Strategic criminal investigation

Investigation over the long term aiming to bring to light constants which could be applied in a general manner. A strategic case study in crime mapping for example would be the designation of ‘hotspots’, or dodgy areas, where the risks of crime are greater than in other neighbourhoods, and a larger police presence would be necessary.

stratosphere

The stratosphere is the second layer of the Earth’s atmosphere after the troposphere. It is located between 8 and 20 kilometers in altitude at its lower limits and between 40 and 60 kilometers at its highest limits.

Striatum

the brain’s nerve structure. The striatum plays a role in voluntary movement but also in automatic motricity. Parkinson’s Disease and Huntington’s Disease are diseases caused by lesions in this part of the brain, and have in part as a consequence a strongly affected motricity.

Strip Tease

Strip Tease is a programme created for RTBF in 1985 by Jean Libon and Marco Lamensch. The Belgian director Benoît Mariage took his first steps there. With the purpose of approaching as closely as possible the facts of society’s life, these documentaries advocate the absence of commentary, the protagonists themselves revealing their private lives over the course of the reportages.

stroma

Tissue that surrounds the cancer cell.

Stromatolite

A fossil limestone deposit left by cyanobacteria and/or other microorganisms from around perhaps 3.5 billion years ago.

Strong Interaction

Physics distinguishes only 4 types of forces: the force of gravity (it keeps us on the Earth!), the electromagnetic force, the weak interaction and the strong interaction. The latter is responsible for the cohesion of the protons and neutrons within an atomic nucleus.

Struye, Paul (1896-1974)

Belgian politician (Christian Socialist Party) He was to become president of the Senate. He was also the author of works on Belgium during the German occupation.

subantarctic

Adjective defining what is situated slightly to the north of Antartica and, generally, south of the sixtieth parallel south.

Subchondral bone

Bone tissue found between the cartilage and the bone properly speaking. It plays an essential role in terms of shock absorbing.

suburbanisation

Also called “rurbanisation”, suburbanisation describes the process of return or flight of city-dwellers to the countryside. In Western Europe, this phenomenon began in the 1960s, notably because of overpopulation in the big towns. The rural areas around these towns were then colonized by city-dwellers wishing to live in a greener and less noisy environment. The final result of this was an expansion of the urban areas to the detriment of rural areas as well as an increase in the price of property in these new suburbs.

Sudden deafness

Sudden loss of hearing in an ear.

Sun Studios

Based in Memphis, Sun Studios is important in the history of rock through the artists who passed through it, in particular thanks to its visionary producer Sam Philips, who signed Elvis Presley, Carl Perkins, Johnny Cash, Jerry Lee Lewis and Roy Orbison.

Sun's corona

The corona is the Sun’s atmosphere. It reaches temperatures of several millions of degrees and extends to distances of several million kilometres. It only becomes visible when the Sun's disk is perfectly obscured, as is the case during a total eclipse of the Sun.

Super-Earth

Name given to a category of exoplanets whose masses are between 1 to 10 times that of the Earth in its broadest definition. Even though a Super-Earth is generally bigger than our planet, it remains a small object compared to gas giants (like Jupiter and Neptune, for example) and is more comparable to Earth than to those giants. The name Super-Earth certainly does not describe a range of conditions making the planet inhabitable. It only concerns the mass of the planet

superconductivity

It is characterised by a double phenomenon: zero electrical resistance and the expulsion of the magnetic field to which the superconductor is submitted. The first one allows the electrical current to be transported with no loss of energy. The second one is responsible for the effect of levitation, for instance, in maglev trains. Superconductivity generally occurs at very low temperatures.

supercritical state

A supercritical state is used to describe the state of matter when this is subjected to a high temperature or pressure. The physical properties of a supercritical fluid such as its density and viscosity are mid-way between the properties of liquids and gases.

superimposition

Two or more images are completely placed on top of one another. By playing with the transparency the spectator sees all of the images simultaneously.

Superlattice

A particular kind of heterostructure made by periodically alternating two or more distinct layers of material ; it possesses a periodic superstructure.

Supermassive black hole

black hole whose mass varies from a million to several billion times that of the sun.

Supernova

A supernova is the explosion that occurs when a star dies. During the supernova chemical elements synthesized within the star during its existence are liberated. The shock wave that accompanies the explosion is favourable for the creation of new stars. Supernovae are among the brightest objects in the universe.

suprachiasmatic nucleus

The suprachiasmatic nucleus is located in the hypothalamus. It regulates melatonin, a hormone secreted when the light fades, plunging the body into a state of somnolence. It is therefore responsible for controlling the circadian rhythm, commonly known as the 'biological clock'.  

surface tension

Surface tension can be briefly described as the force that exists at the interface between two media. It exists because molecules lying at the boundary between two media have more energy. An analog phenomenon is observed with penguins in freezing Antartic winters – those at the border of their group need to spend more energy in order to keep warm. The same idea applies to molecules, which “feel more comfortable” when they are completely surrounded by other similar molecules. Nature tend to minimize the number of those molecules exposed to the outside, therefore reducing the surface area of interfaces. When a boundary between two media is stretched, surface tension brings it down to the smallest surface area possible.

While this phenomenon is very fast and occurs at a microscopic level, it has many macroscopic consequences. When surface tension dominates other forces, water tends to form spheres in the air (drops) because the sphere is the smallest possible surface. Wetting is driven by liquid surface tension, but it also depends on the solid medium that the liquid attempts to wet. If a drop of water is placed on a material whose surface tension is weak (a plastic film for example), the internal forces of attraction of the water drop will be stronger; the drop will therefore be practically spherical and will minimize its contact area with the underlying solid. In this case the solid is not wet: this is what happens when rain falls on a lotus leaf and forms water pearls that bounce off its surface. On the contrary, if we put a drop of water on clean glass, the drop strongly spreads out and wets the surface. It is this same phenomenon of surface tension that explains why some insects can walk on water (even though their density is greater than that of the water): equipped with hydrofuge hairs under the legs, they never break the surface tension of the water and fall into it.

One last example: it is also surface tension that explains why… greasy plates need to be cleaned with hot water and “washing-up liquid”.  It is because soap is a tensioactive carbonated chain that contains a hydrophobic side and a hydrophilic side. The latter will link onto molecules of water and decrease their “frustration” to be in contact with oil molecules. In other words it reduces the interfacial tension between oil and water, and it then allows water to disperse particles of fat more easily.

surfactant products 

Surfactant or surface-active products are products which modify the surface tension between two surfaces.

sustainable city

A sustainable city is a city:
- capable of sustaining itself in time, of keeping an identity, a collective sense, and dynamism in the long term,
- that offers a quality of life in all respects (in connection with functional, social and cultural diversity),
- that stimulates collective participation in urban projects (urban planning, Agenda 21).

This definition of the sustainable city is proposed by Cyria Emelianoff (Comment définir une ville durable)

Swarte, Joost (1947- )

A Dutch comics author born in 1947. He is one of the representatives of the style which he describes as “clear line”, a refined style which he borrowed from Hergé. He enjoyed international success in the 1980s and was the subject of a monograph published by Futuropolis in 1984.

Sweetener

Said of a substance or product which provides a sugary taste. A sugar substitute is a sweetening product which does not contain sugar (saccharose), is low in calories and which most of the time has the advantage of not causing tooth cavities.

swim bladder

This is the diverticulum of the digestive tube which forms a pocket of air in the oesophagus. An air-filled bladder which gives the fish buoyancy. Some of the fish that live on the bottom of the oceans do not have this. In some fish, it can vibrate due to muscular activity and therefore produce sound. Finally, it plays a role in the hearing ability of the fish. By the difference of density in water, it can distort itself under pressure from an external sound. This distortion creates a signal (= movements of particles) which can then be captured by the ear. It has been proved that the closer the swim bladder is located to the ear, the better the fish’s hearing. Certain fish, particularly Synodontis, have even developed Weberian ossicles, a chin of three ossicles which form a joint between the bladder and the ear, and which retransmit by the distortion of the bladder wall. A fish with Weberian ossicles can hear frequencies between 0 and 5000 hertz. A fish which does not have this apparatus will not hear above 2000 hertz.

Symbiosis

intimate and durable association between two species that are heterospecific (belonging to two different species), and sometimes more than two. The organisms are described as symbiotes. The larger is called the host. Symbiosis can be of two types:
•    ectosymbiosis: the symbiote lives on the surface of the host (this includes the intestinal tract and the canals of the exocrine glands)
•    endosymbiosis: the symbiote is located in the intercellular or intracellular space (intravacuolar or free in the cytoplasm)

Symbol

Religious term from the Christian Latin of the Middle Ages symbolum, referring to a shared profession of faith, through which Christians recognised themselves amongst each other. It is often used, as a synonym of ‘credo’, in the expression the Creed of Nicaea.

sympodial growth

A form of plant growth in which lateral meristems take over plant growth after the production of a flower or inflorescence by the main (apical) meristem.

Synapse

Area of connection and transmission of information between two neurones or between a neurone and a muscle cell. Whatever its anatomical character, the synapse includes a presynaptic element that sends a chemical message, a postsynaptic element that receives it and, between these two elements, a synaptic space or cleft.

Synaptic cleft

The space between two nerve cells which constitutes a junction area through which the chemical message passes from one neurone to another, bringing about the excitation or inhibition of the latter.

Synaptic cleft

Space between two neurons where electrochemical communication takes place.

Synaptic connection

Connection between the synapses. The synapses are zones situated between two neurones which allow information to be integrated and filtered within the brain.

synchrony

A perspective that considers its object at a particular time of its development, without taking into account prior or posterior temporal variations (thus considering the object as stable). In terms of language, it is thus a matter of a grouping of linguistic facts considered as forming a functional system at a given moment of the development of a language.

Synchrotron

A synchrotron is a particle accelerator constituted of a unique empty circular tube. Vast levels of energy can be achieved thanks to a magnetic field that increases with the speed of the particles. Significant diameters are necessary for the particles to achieve the desired speeds. For instance, the European synchrotron in Grenoble is almost one kilometre in diameter.

Synodontis

A genus that includes several species of catfish.

Synovial fluid

Loose or diarthritic articulations (such as those of the neck or the knee) are also called synovial joints because the extremities of the bones are housed in a synovial envelope (called the synovial membrane) filled with a lubricating liquid, synovial fluid.

Synthetic product

Product made up of chemically altered substances.

Syrphid

A flying insect from the Diptera family which lays its eggs in aphid colonies. The larvae which emerge from then feed on these pests.

systemic

Systemic analysis is the study of a system, i.e. a collection of elements that don’t work in a linear way but in a more complex manner. In this case, a system is comprised of criteria that interact and influence each other. That is why it is necessary to apply a global approach to the problem.

Systems biology

Approach to biology which aims to study all interactions between elements (DNA, proteins, metabolites etc.) of a biological system.

systems theory

In sociology, the systems theory that was developed in the 1960s by David Easton views society's different components as permeable, interdependent systems that are part of a dynamic feedback loop. It distinguishes between the social system, which includes all of society, and the political system, which includes all the members and institutions which make decisions and take actions that are then imposed on the entire society. There is a feedback loop between the two systems that is initiated by pressure from a social group that responds either positively or negatively to the political group (Easton referred to this pressure as “inputs”). The political group will then respond in order to neutralize this pressure (these reactions are called “outputs”).  

Other than its simplicity, this theory presents at least two advantages. Firstly, it allows us to understand how the political socialisation process works with young people. For Easton, the idea was to socialise young people to develop a positive attitude towards the political system, thus ensuring that the system would function without constant conflict. Secondly, its dynamic and interdependent nature reveals the permeability of the boundaries between the political and social systems.

Systole

The four parts of the heart (Left and right ventricles, left and right atriums), have a systole and a diastole so that blood can be propelled across the cardio-vascular system. While the systole or systolic ejection contracts the ventricles, the diastole releases them. This enables the valves to open and send blood to the arteries.



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