In Unified Modeling Language (UML), an **Actor** represents a role that a user or any other system plays when interacting with the system being modeled. Actors are typically used in use case diagrams to illustrate the interactions between the system and the external entities that influence its behavior. ### Key Characteristics of Actors in UML: 1. **External Role**: An actor is not part of the system itself; instead, it exists outside the system and interacts with it.

The Adamic–Adar index is a measure used in network theory and social network analysis to quantify the similarity between two nodes based on their shared connections. Specifically, it evaluates the likelihood that two nodes will connect in the future, based on their common neighbors in a graph.

Adam Wierman is a professor in the Department of Computing and Mathematical Sciences at the California Institute of Technology (Caltech). His research interests primarily include areas such as queuing theory, machine learning, and algorithms, often with applications in networking, data analysis, and other fields. He has contributed to various topics in operations research and has published numerous papers in academic journals.

Additive smoothing, also known as Laplace smoothing, is a technique used in probability estimates, particularly in natural language processing and statistical modeling, to handle the problem of zero probabilities in categorical data. When estimating probabilities from observed data, especially with limited samples, certain events may not occur at all in the sample, leading to a probability of zero for those events. This can be problematic in applications like language modeling, where a lack of observed data can lead to misleading conclusions or unanticipated behavior.

Westerhout 43 is a notable star-forming region located in the constellation of Sagittarius. It is recognized as a prominent prototype of H II regions, which are large clouds of gas and dust in space where new stars are born. The region is specifically part of a giant molecular cloud, and its designation reflects the work of astronomers who cataloged various stellar and nebulae objects.

The term "Aeon" can refer to different concepts depending on the context: 1. **Philosophical and Historical Context**: In ancient philosophy, particularly in Gnosticism, an "aeon" refers to a divine being or emanation that is part of the fullness of God, known as the Pleroma. These aeons are often considered to be aspects of the divine and play a role in the creation and structure of the universe.

AES11, developed by the Audio Engineering Society (AES), is a standard that provides guidelines for the measurement of digital audio systems, particularly for evaluating the performance of digital audio equipment and systems. Specifically, AES11 focuses on the measurement of the frequency response, distortion, and other relevant parameters to ensure that digital audio signals are processed accurately and effectively. The standard outlines various test signals and measurement techniques that can be used to assess the performance of digital audio systems.

Fyodor Klement does not appear to refer to a widely recognized figure or concept in literature, history, or popular culture as of my last knowledge update in October 2023. It’s possible that the name is not well-known or it may refer to a lesser-known individual or fictional character.

In typography, "agate" refers to a specific unit of measurement, traditionally used in printing and typesetting. An agate is defined as a type size that measures approximately 5.5 points (or about 1/12 of an inch). It is often used for setting very small type, such as in classified ads or listings in newspapers. The use of agate as a typographic measurement dates back to the days of letterpress printing.

Agnès Fienga is a prominent figure in the field of digital marketing and media, particularly known for her work in the realm of data and analytics. She has experience in various high-profile roles and has contributed to the development of strategies that enhance the digital presence of businesses. Additionally, she is involved in discussions around the impact of technology on the media landscape and is a speaker at various industry conferences.

Air separation is a process that involves separating the components of air into its primary constituents, which are primarily nitrogen (approximately 78%), oxygen (approximately 21%), and small amounts of other gases such as argon, carbon dioxide, and trace gases. This separation is essential for various industrial applications, including the production of pure oxygen for medical use, nitrogen for food preservation and chemical processes, and argon for welding and metal fabrication.

Airy wave theory is a mathematical model used to describe the propagation of surface waves on deep water. Developed by the British mathematician and astronomer George Biddell Airy in the 19th century, it provides a framework for understanding wave properties such as amplitude, wavelength, phase velocity, and wave energy.

Albert Folch Folch is a physicist and an academic known for his work in fields such as biophysics, nanotechnology, and microfluidics. He is affiliated with educational institutions and has made significant contributions to research in these areas.

Alessandro Serpieri is an Italian economist known for his work in the field of public economics and policy, particularly regarding fiscal policies and the impact of government actions on the economy. His contributions often focus on the analysis of economic behavior in the context of social and institutional frameworks.

Alexander Samarskii is a notable Russian mathematician and scholar, primarily recognized for his contributions to the fields of numerical analysis and computational mathematics. He has authored and co-authored a variety of research papers and books, particularly focusing on numerical methods for solving partial differential equations and problems in mathematical modeling. His work has been influential in the development of numerical techniques used in scientific computing, and he has been involved in the education of many students in these fields.

Alexey Chervonenkis is a prominent Russian mathematician and statistician, best known for his contributions to the fields of statistical learning theory and probability theory. He is particularly recognized for his work on the concept of VC (Vapnik-Chervonenkis) dimension, which is a fundamental concept in statistical learning theory that characterizes the capacity of a statistical model to fit a set of data points.

Alfred Music is a prominent music publishing company that specializes in educational and instructional music materials. Founded in 1922 by Alfred P. Morgan, it has grown to become a leading publisher of music books, sheet music, and educational resources for musicians of all ages and skill levels. The company produces a wide range of materials, including method books for various instruments, music theory resources, choral music, and arrangements for schools and music educators.

Alice is a scientific instrument designed for use aboard the New Horizons spacecraft, which was launched by NASA to conduct a flyby of Pluto and its moons in 2015. Alice is a ultraviolet (UV) spectrograph, which means it is capable of measuring ultraviolet light across a range of wavelengths. The primary goals of the Alice instrument are to study the composition and structure of the atmospheres of Pluto and its moons, as well as to analyze the surface properties of these celestial bodies.

An alidade is a precision optical instrument used primarily in surveying and navigation to take accurate angular measurements. It typically consists of a sighting device, such as a telescope or a straightedge, mounted on a base or a transit. The instrument allows the user to align the alidade with a distant object, enabling the measurement of the angle relative to a reference line.

The Almost Mathieu operator is a significant example of a quasi-periodic Schrödinger operator in mathematical physics and condensed matter theory. It describes a quantum mechanical system in which a particle is subjected to a periodic potential that is modulated by an irrational rotation. Mathematically, the Almost Mathieu operator can be expressed on a Hilbert space of square-summable functions, typically defined on the integers.