A spark-ignition (SI) engine is a type of internal combustion engine that uses a spark plug to ignite a fuel-air mixture. This type of engine is typically found in gasoline-powered vehicles. Here are some key characteristics and components of spark-ignition engines: 1. **Fuel Type**: SI engines primarily run on gasoline, which is a volatile liquid that vaporizes easily and mixes with air.

A cognitive map is a mental representation of spatial knowledge and the environment that an individual uses to navigate and understand their surroundings. The concept can also extend to include knowledge about relationships between objects, events, and concepts in both physical and abstract spaces. Here are some key points about cognitive maps: 1. **Spatial Awareness**: Cognitive maps help us orient ourselves in physical space, allowing us to understand the layout of places such as our home, neighborhood, or city.

The sociology of space is a subfield of sociology that examines how social relations and structures are influenced by and interact with physical spaces and environments. It encompasses the study of the ways in which spatial arrangements, such as urban and rural environments, buildings, public spaces, and even virtual spaces, shape social behaviors, interactions, and power dynamics.

Nicholas Fisher is a statistician known for his work in statistical methodology and applications. He has contributed to various fields, particularly in areas such as statistical modeling, data analysis, and the development of statistical theory. Fisher's research often intersects with practical applications, providing insights that can be utilized in various industries, including health sciences, social sciences, and environmental studies.

A spectral sequence is a mathematical tool used in algebraic topology, homological algebra, and related fields to compute homology or cohomology groups that may be difficult to compute directly. It provides a method to systematically approximate these groups through a sequence of pages (typically indexed by integers) and associated differentials.

Fredholm theory is a branch of functional analysis that deals with Fredholm operators, which are a specific class of bounded linear operators between Banach spaces. Named after the mathematician Ivar Fredholm, it plays a crucial role in the study of integral equations, partial differential equations, and various problems in mathematical physics and applied mathematics.

In functional analysis, the notion of the spectrum of an operator is a fundamental concept that extends the idea of eigenvalues from finite-dimensional linear algebra to more general settings, particularly in the study of bounded linear operators on Banach spaces and Hilbert spaces.

The Krein–Rutman theorem is an important result in functional analysis and the theory of linear operators, particularly in the study of positive operators on a Banach space. It provides conditions under which a positive compact linear operator has a dominant eigenvalue and corresponding eigenvector. This theorem has significant implications in various fields, including differential equations, fixed point theory, and mathematical biology.

Paul Gauduchon is a French mathematician known for his work in differential geometry and general relativity. He is particularly recognized for the Gauduchon metrics, which are a special class of hermitian metrics on complex manifolds. His contributions have been influential in the study of complex geometry and the properties of Kähler and Hermitian manifolds.

A "rigged Hilbert space" (also known as a Gelfand triplet) is a mathematical concept used in quantum mechanics and functional analysis to provide a rigorous framework for dealing with the states and observables in quantum theory. The term describes a specific construction involving three spaces: a Hilbert space, a dense subspace, and its dual.

The Selberg zeta function is a mathematical object that arises in the study of Riemann surfaces and in number theory, particularly in relation to the theory of automorphic forms and the spectral theory of certain types of differential operators. It was introduced by the mathematician Atle Selberg in the 1950s. ### Definition: The Selberg zeta function is associated with a hyperbolic Riemann surface (or a more general Riemann surface with a finite volume).

An Integral Field Spectrograph (IFS) is an advanced astronomical instrument used to obtain detailed spectral information over a two-dimensional field of view. It combines imaging and spectroscopy, allowing astronomers to study both the spatial distribution and the spectral characteristics of light from celestial objects simultaneously.

An imaging spectrometer is a sophisticated optical instrument used to capture image data at many different wavelengths across the electromagnetic spectrum. By combining the functionalities of both imaging and spectroscopy, it allows scientists and researchers to obtain detailed spectral information for each pixel of an image, enabling them to analyze the composition and properties of materials.

NIRSpec, or the Near Infrared Spectrograph, is a scientific instrument aboard the James Webb Space Telescope (JWST). It is designed to perform spectroscopy in the near-infrared range (0.6 to 5 microns), allowing scientists to study the composition, temperature, density, and motion of various astronomical objects, including stars, galaxies, and exoplanets.

The Venus Emissivity Mapper (VEM) is an instrument designed to study Venus, particularly its surface composition and geology. Part of NASA's upcoming VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) mission, VEM will utilize advanced infrared spectroscopy to analyze the thermal emissions from the planet's surface.

Anders Jonas Ångström (1814–1874) was a Swedish physicist and astronomer known for his significant contributions to the field of spectroscopy and the study of light. He is best recognized for his work in measuring the wavelengths of various spectral lines and for founding the science of spectrometry. Ångström is particularly noted for his studies of the spectrum of light emitted by different elements, which laid the groundwork for modern spectroscopy.

A Computed Tomography Imaging Spectrometer (CTIS) is an advanced imaging technology that combines principles from both computed tomography (CT) and spectroscopy. It is used to capture detailed images of objects while simultaneously measuring their spectral properties, allowing for the analysis of material composition and other characteristics at different wavelengths of light. ### Key Features of CTIS: 1. **Imaging and Spectroscopy**: CTIS can produce spatial images while capturing spectral information across a range of wavelengths.

A DU spectrophotometer is a type of laboratory instrument used for measuring the absorbance or transmittance of light by a sample at specific wavelengths. The "DU" in DU spectrophotometer typically refers to a specific model series produced by Beckman Coulter, a company known for its laboratory instruments and analytical devices.

The Dobson ozone spectrophotometer is an instrument used to measure the concentration of ozone in the Earth's atmosphere. Developed in the 1920s by British scientist G. M. B. Dobson, it became one of the most significant tools for monitoring atmospheric ozone levels, especially in the stratosphere.

MERIS, or the Medium Resolution Imaging Spectrometer, is an instrument that was primarily used aboard the European Space Agency's Envisat satellite, which was launched in 2002. MERIS was designed for Earth observation, and its main purpose was to monitor the Earth's land, oceans, and atmosphere at medium spatial resolution.