Scientific News
Articles across mathematics, physics, chemistry, biology, and astronomy.
Science
Sidereal year
A sidereal year (, US also ; from Latin sidus 'asterism, star'), also called a sidereal orbital period, is the time that Earth or another planetary body takes to orbit the Sun once with respect to the fixed stars. Thus, a sidereal year is the interval required for Earth to travel once around the ecliptic, completing one revolution about the Sun and returning to the same orbital position relative
8/25/2026
Science
Sides of an equation
In mathematics, LHS is informal shorthand for the left-hand side of an equation. Similarly, RHS is the right-hand side. The two sides have the same value, expressed differently, since equality is symmetric. More generally, these terms may apply to an inequation or inequality; the right-hand side is everything on the right side of a test operator in an expression, with LHS defined similarly.
8/25/2026
Science
Significand
The significand (also coefficient, sometimes argument, or more ambiguously mantissa, fraction, or characteristic) is the first (left) part of a number in scientific notation or related concepts in floating-point representation, consisting of its significant digits. For negative numbers, it does not include the initial minus sign. Depending on the interpretation of the exponent, the significand may
8/25/2026
Science
Sign bit
In computer science, the sign bit is a bit in a signed number representation that indicates the sign of a number. Although only signed numeric data types have a sign bit, it is invariably located in the most significant bit position, so the term may be used interchangeably with "most significant bit" in some contexts. Almost always, if the sign bit is 0, the number is non-negative (positive or ze
8/25/2026
Science
Sierpiński's constant
Sierpiński's constant is a mathematical constant usually denoted as K. One way of defining it is as the following limit: K = lim n → ∞ [ ∑ k = 1
8/25/2026
Science
Signed distance function
In mathematics and its applications, the signed distance function or signed distance field (SDF) is the orthogonal distance of a given point x to the boundary of a set Ω in a metric space (such as the surface of a geometric shape), with the sign determined by whether or not x is in the interior of Ω. The function has positive values at points x inside Ω, it decreases in value as x approaches the b
8/25/2026
Science
Sidera Lodoicea
Sidera Lodoicea is the name given by the astronomer Giovanni Domenico Cassini to the four moons of Saturn discovered by him in the years 1671, 1672, and 1684 and published in his Découverte de deux nouvelles planètes autour de Saturne in 1673 and in the Journal des sçavans in 1686. These satellites are today known by the following names, given in 1847: Iapetus or Saturn VIII, discovered October
8/25/2026
Science
Sideblog
A sideblog is a feature on a website, particularly a blog, that allows one to communicate smaller snippets of information than an actual blog post. The reasoning is that a blog post will require thought, argument and some semantic structuring of the post, while a sideblog typically displays "brief asides". A sideblog is meant to illustrate your immediate thoughts, movements or status update, and i
8/25/2026
Science
Silicate perovskite
Silicate perovskite is either (Mg,Fe)SiO3 (the magnesium end-member is called bridgmanite) or CaSiO3 (calcium silicate known as davemaoite) when arranged in a perovskite structure. Silicate perovskites are not stable at Earth's surface, and mainly exist in the lower part of Earth's mantle, between about 670 and 2,700 km (420 and 1,680 mi) depth. They are thought to form the main mineral phases of
8/25/2026
Science
Siliceous ooze
Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. Siliceous oozes are largely composed of the silica-based skeletons of microscopic marine organism
8/25/2026
Science
Sidney Fernbach Award
The Sidney Fernbach Award established in 1992 by the IEEE Computer Society, in memory of Sidney Fernbach, one of the pioneers in the development and application of high performance computers for the solution of large computational problems as the Division Chief for the Computation Division at Lawrence Livermore Laboratory from the late 1950s through the 1970s. A certificate and $2,000 are awarded
8/25/2026
Science
Sideloading
Sideloading is the process of transferring files between two local devices, in particular between a personal computer and a mobile device such as a mobile phone, smartphone, PDA, tablet, portable media player or e-reader. Sideloading typically refers to media file transfer to a mobile device via USB, Bluetooth, WiFi or by writing to a memory card for insertion into the mobile device, but also appl
8/25/2026
Science
Sigma coordinate system
The sigma coordinate system is a common coordinate system used in computational models for oceanography, meteorology and other fields where fluid dynamics are relevant. This coordinate system receives its name from the independent variable σ {\displaystyle \sigma } used to represent a scaled pressure level. Models that use a sigma coordinate system inclu
8/25/2026
Science
Sidney Powers Memorial Award
The Sidney Powers Memorial Award is a gold medal awarded by the American Association of Petroleum Geologists in recognition of distinguished and outstanding contributions to, or achievements in, petroleum geology. The award is named after Sidney Powers.
8/25/2026
Science
Sight reduction
In astronavigation, sight reduction is the process of deriving from a sight (in celestial navigation usually obtained using a sextant) the information needed for establishing a line of position, generally by intercept method. Sight is defined as the observation of the altitude, and sometimes also the azimuth, of a celestial body for a line of position; or the data obtained by such observation. The
8/25/2026
Science
Sigma-D relation
The Sigma-D relation, or Σ-D Relation, is the claimed relation between the radio surface brightness and diameter of a supernova remnant. It is generally regarded as of limited physical use, since it has very large scatter and is dominated by observational selection biases.
8/25/2026
Science
Sigma electron donor-acceptor
The sEDA parameter (sigma electron donor-acceptor) is a sigma-electron substituent effect scale, described also as inductive and electronegativity related effect. There is also a complementary scale - pEDA. The more positive is the value of sEDA the more sigma-electron donating is a substituent. The more negative sEDA, the more sigma-electron withdrawing is the substituent (see the table below). T
8/25/2026
Science
Silicon isotope biogeochemistry
Silicon isotope biogeochemistry is the study of environmental processes using the relative abundance of Si isotopes. As the relative abundance of Si stable isotopes varies among different natural materials, the differences in abundance can be used to trace the source of Si, and to study biological, geological, and chemical processes. The study of stable isotope biogeochemistry of Si aims to quanti
8/25/2026
Science
Sikidy
Sikidy is a form of algebraic geomancy practiced by Malagasy peoples in Madagascar. It involves algorithmic operations performed on random data generated from tree seeds, which are ritually arranged in a tableau called a toetry and divinely interpreted after being mathematically operated on. Columns of seeds, designated "slaves" or "princes" belonging to respective "lands" for each, interact symbo
8/25/2026
Science
SigMF
SigMF is a standard file format for storing and organizing digitized radio frequency (RF) signals and corresponding metadata, supporting time series real or complex-valued signals. A single SigMF "Recording" consists of two files: 1) a binary file containing only the time series digitized samples, and 2) a metadata file describing the contents and capture details of those samples. The metadata is
8/25/2026
Science
Shaping codes
In digital communications shaping codes are a method of encoding that changes the distribution of signals to improve efficiency.
8/25/2026
Science
Sextant
A sextant is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. Its primary use is to measure the angle between an astronomical object and the horizon in celestial navigation. Estimating this angle, the altitude, is known as sighting or shooting the object, or taking a sight. The angle and the time when it was measured can be used to calculate
8/25/2026
Science
Set-builder notation
In mathematics and more specifically in set theory, set-builder notation is a notation for specifying a set by a property that characterizes its members. Roster notation is a similar notation used for specifying a set by enumerating its elements. Specifying sets by member properties is allowed by the axiom schema of specification. This is also known as set comprehension and set abstraction.
8/25/2026
Science
Session (computer networking)
In computer science and networking, a session is a two-way link, a relatively high layer in the OSI stack enabling interactive information exchange between two or more communication devices or ends – be they computers, automated systems, or live active users (see login session). A session is established at a certain point in time, and then 'torn down' - brought to an end - at some later point. A s
8/25/2026
Science
Sex linkage
Sex linkage describes the sex-specific patterns of inheritance and presentation when a gene mutation (allele) is present on a sex chromosome (allosome) rather than a non-sex chromosome (autosome). In humans, these are termed X-linked recessive, X-linked dominant and Y-linked. The inheritance and presentation of all three differ depending on the sex of both the parent and the child. This makes them
8/25/2026
Science
Sex-chromosome dosage compensation
Dosage compensation is the process by which organisms equalize the expression of genes between members of different biological sexes. Across species, different sexes are often characterized by different types and numbers of sex chromosomes. In order to neutralize the large difference in gene dosage produced by differing numbers of sex chromosomes among the sexes, various evolutionary branches have
8/25/2026
Science
Shadow biosphere
A shadow biosphere is a hypothetical microbial biosphere of Earth that would use radically different biochemical and molecular processes from those of known life. Although life on Earth is fairly well studied, if a shadow biosphere exists, it may be unnoticed because the exploration of micro-organisms targets primarily the biochemistry of macro-organisms.
8/25/2026
Science
Sextant (astronomy)
In astronomy, sextants are devices depicting a sixth of a circle, used primarily for measuring the position of stars. There are two types of astronomical sextants, mural instruments and frame-based instruments. They are of significant historical importance, but have been replaced over time by transit telescopes, other astrometry techniques, and satellites such as Hipparcos.
8/25/2026
Science
Shaheen-III
The Shaheen-III (شاہین– ۳ ; lit. Falcon), is a land-based medium-range ballistic missile (MRBM) operated by the Pakistan Army, which first test-fired the weapon on 9 March 2015. Development began in secrecy in the early 2000s in response to India's Agni-III, Shaheen was successfully tested on 9 March 2015 with a range of 2,750 km (1,710 mi), which enables it to strike all of India and reach deep i
8/25/2026
Science
Sessility (motility)
Sessility, a property of certain animals, is a lack of self-locomotion. Sessile animals do not have natural motility, and are immobile unless there are external forces (such as water currents). Usually, sessile animals are permanently attached to a solid object, such as a rock, a dead tree trunk, or a human-made object such as a buoy or ship's hull. Organisms such as corals lay down their own subs
8/25/2026
Science
Session multiplexing
Session multiplexing in a computer network is a service provided by the transport layer (see OSI Layered Model). It multiplexes several message streams, or sessions onto one logical link and keeps track of which messages belong to which sessions (see session layer). An example of session multiplexing—a single computer with one IP address has several websites open at once.
8/25/2026
Science
Shadow square
The shadow square, also known as an altitude scale, was an instrument used to determine the linear height of an object, in conjunction with the alidade, for angular observations. An early example was described in an Arabic treatise likely dating to 9th or 10th-century Baghdad. Shadow squares are often found on the backs of astrolabes.
8/25/2026
Science
Seymour Cray Computer Engineering Award
The Seymour Cray Computer Engineering Award, also known as the Seymour Cray Award, is an award given by the IEEE Computer Society, to recognize significant and innovative contributions in the field of high-performance computing. The award honors scientists who exhibit the creativity demonstrated by Seymour Cray, founder of Cray Research, Inc., and an early pioneer of supercomputing. Cray was an Am
8/25/2026
Science
Sevenfold Sun miracle
The Sevenfold Sun Miracle was an atmospheric phenomenon witnessed in Gdańsk in 1661. It was a complex halo phenomenon, and was described by Georg Fehlau, the pastor of the St Marien church, in a sermon two weeks later, which was then published under the title Siebenfältiges Sonnenwunder oder sieben Nebensonnen, so in diesem 1661 Jahr den 20. Februar neuen Stils am Sonntage Sexagesima um 11 Uhr bis
8/25/2026
Science
Sex-linked barring
Sex-linked barring is a plumage pattern on individual feathers in chickens, which is characterized by alternating pigmented and apigmented bars. The pigmented bar can either contain red pigment (phaeomelanin) or black pigment (eumelanin) whereas the apigmented bar is always white. The locus is therefore often referred to as an 'eumelanin diluter' or 'melanin disruptor'. Typical sex-linked barred b
8/25/2026
Science
Shannon Appelcline
Shannon Appelcline is a historian of tabletop role-playing games and a game designer. Two different editions of his book Designers & Dragons have won ENNIE Awards.
8/25/2026
Science
Sexual segregation (biology)
In biology, sexual segregation is the differential use of space, habitats, and resources by males and females, or the separation of males and females into different social groups outside the breeding season. Sexual segregation is widespread among animals, especially among vertebrates that live in groups, and has also been observed in plants. It was first formally proposed by Charles Darwin in his
8/25/2026
Science
Session type
In type theory, session types are used to ensure correctness in concurrent programs. They guarantee that messages sent and received between concurrent programs are in the expected order and of the expected type. Session type systems have been adapted for both channel and actor systems. Session types are used to ensure desirable properties in concurrent and distributed systems, i.e. absence of comm
8/25/2026
Science
Shadow effect
The shadow effect is a phenomenon seen in genetic studies that use noninvasive genetic data collection methods. It occurs when there are not enough loci and/or loci that have low variance of alleles within the population. As a result, researchers can capture two separate individuals and mistakenly label them as the same individual. This can create a negative bias in the data and portray a populati
8/25/2026
Science
Sesquisulfide
Α sesquisulfide is a compound that has the composition M2S3 where M is the element and S is sulfur. Boron sesquisulfide, B2S3 Aluminium sesquisulfide, Al2S3 Scandium sesquisulfide, Sc2S3 Titanium sesquisulfide, Ti2S3 Chromium sesquisulfide, Cr2S3 Gallium sesquisulfide, Ga2S3 Arsenic sesquisulfide, As2S3 Yttrium sesquisulfide, Y2S3 Rhodium sesquisulfide, Rh2S3 Antimony sesquisulfide, Sb2S3 Cerium
8/25/2026
Science
Shakuyaku-kanzo-to
Shakuyaku-kanzo-to (Japanese: 芍薬甘草湯, Hepburn: Shakuyaku-kanzō-tō) or shao-yao-gan-cao-tang (Chinese: 芍药甘草丸; pinyin: sháo yào gān cǎo wán) is a traditional herbal medicine used in both Kampo (Japanese) and Chinese medicine. It consists of an equal combination of the roots of Chinese peony root (Radix Paeoniae, shakuyaku) and licorice root (Radix Glycyrrhizae, kanzō), primarily used for its antispas
8/25/2026
Science
Shannon–Hartley theorem
In information theory, the Shannon–Hartley theorem tells the maximum rate at which information can be transmitted over a communications channel of a specified bandwidth in the presence of noise. It is an application of the noisy-channel coding theorem to the archetypal case of a continuous-time analog communications channel subject to Gaussian noise. The theorem establishes Shannon's channel capac
8/25/2026
Science
Shaw Prize
The Shaw Prize is a set of three annual awards presented by the Shaw Prize Foundation in the fields of astronomy, medicine and life sciences, and mathematical sciences. Established in 2002 in Hong Kong, by Hong Kong entertainment mogul and philanthropist Run Run Shaw (邵逸夫), the awards honour "individuals who are currently active in their respective fields and who have recently achieved distinguish
8/25/2026
Science
Shannon capacity of a graph
In graph theory, the Shannon capacity of a graph is a graph invariant defined from the number of independent sets of strong graph products. It is named after American mathematician Claude Shannon. It measures the Shannon capacity of a communications channel defined from the graph, and is upper bounded by the Lovász number, which can be computed in polynomial time. However, the computational comple
8/25/2026
Science
Shannon's source coding theorem
In information theory, Shannon's source coding theorem (or noiseless coding theorem) establishes the statistical limits to possible data compression for data whose source is an independent identically-distributed random variable, and the operational meaning of the Shannon entropy. Named after Claude Shannon, the source coding theorem shows that, in the limit, as the length of a stream of independe
8/25/2026
Science
Shear zone
In geology, a shear zone is a thin zone within the Earth's crust or upper mantle that has been strongly deformed, due to the walls of rock on either side of the zone slipping past each other. In the upper crust, where rock is brittle, the shear zone takes the form of a fracture called a fault. In the lower crust and mantle, the extreme conditions of pressure and temperature make the rock ductile.
8/25/2026
Science
Shell theorem
In classical mechanics, the shell theorem gives gravitational simplifications that can be applied to objects inside or outside a spherically symmetric body. This theorem has particular application to astronomy. Isaac Newton proved the shell theorem and stated that: A spherically symmetric body affects external objects gravitationally as though all of its mass were concentrated at a point at its c
8/25/2026
Science
Shear (geology)
In geology, shear is the response of a rock to deformation usually by compressive stress and forms particular textures. Shear can be homogeneous or non-homogeneous, and may be pure shear or simple shear. Study of geological shear is related to the study of structural geology, rock microstructure or rock texture and fault mechanics. The process of shearing occurs within brittle, brittle-ductile, a
8/25/2026
Science
Shannon–Weaver model
The Shannon–Weaver model is one of the first models of communication. Initially published in the 1948 paper "A Mathematical Theory of Communication", it explains communication in terms of five basic components: a source, a transmitter, a channel, a receiver, and a destination. The source produces the original message. The transmitter translates the message into a signal, which is sent using a chan
8/25/2026
Science
Shapley–Sawyer Concentration Class
The Shapley–Sawyer Concentration Class is a classification system on a scale of one to twelve using Roman numerals for globular clusters according to their concentration. The most highly concentrated clusters such as M75 are classified as Class I, with successively diminishing concentrations ranging to Class XII, such as Palomar 12. (The class is sometimes given with numbers [Class 1–12] rather th
8/25/2026